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Sample records for rate calorimetry study

  1. Accelerating rate calorimetry: A new technique for safety studies in lithium systems

    NASA Technical Reports Server (NTRS)

    Ebner, W. B.

    1982-01-01

    The role of exothermic reactions in battery test modes is discussed. The exothermic reactions are characterized with respect to their time-temperature and time-pressure behavior. Reactions occuring for any major exotherm were examined. The accelerating rate calorimetry methods was developed to study lithium cells susceptibility to thermal runaway reactions following certain abuse modes such as forced discharge into reversal and charging.

  2. Calorimetry

    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:

  3. A systematic study on the reactivity of different grades of charged Li[NixMnyCoz]O2 with electrolyte at elevated temperatures using accelerating rate calorimetry

    NASA Astrophysics Data System (ADS)

    Ma, Lin; Nie, Mengyun; Xia, Jian; Dahn, J. R.

    2016-09-01

    The reactivity between charged Li[NixMnyCoz]O2 (NMC, with x + y + z = 1, x:y:z = 1:1:1 (NMC111), 4:4:2 (NMC442), 5:3:2 (NMC532), 6:2:2 (NMC622) and 8:1:1 (NMC811)) and traditional carbonate-based electrolytes at elevated temperatures was systematically studied using accelerating rate calorimetry (ARC). The ARC results showed that the upper cut-off potential and NMC composition strongly affect the thermal stability of the various NMC grades when traditional carbonate-based electrolyte was used. Although higher cut-off potential and higher Ni content can help increase the energy density of lithium ion cells, these factors generally increase the reactivity between charged NMC and electrolyte at elevated temperatures. It is hoped that this report can be used to help guide the wise selection of NMC grade and upper cut-off potential to achieve high energy density Li-ion cells without seriously compromising cell safety.

  4. Monte Carlo studies of uranium calorimetry

    SciTech Connect

    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.

  5. Oxygen Consumption Rate and Energy Expenditure in Mice: Indirect Calorimetry.

    PubMed

    Kim, Eun Ran; Tong, Qingchun

    2017-01-01

    Global obesity epidemic demands more effective therapeutic treatments and better understanding of obesity pathophysiology. Since obesity results from energy imbalance, accurate quantification of energy intake and energy expenditure (EE) becomes an essential prerequisite to phenotype the cause for obesity development. Indirect calorimetry has long been used as one of the most established methods in EE quantification by detecting changes in levels of O2 consumption and CO2 production. In this article, we describe procedures and important considerations for an effective measurement using indirect calorimetry.

  6. Fast Scanning Calorimetry Studies of Supercooled Liquids and Glasses

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Deepanjan

    This dissertation is a compilation of research results of extensive Fast Scanning Calorimetry studies of two non-crystalline materials: Toluene and Water. Motivation for fundamental studies of non-crystalline phases, a brief overview of glassy materials and concepts and definitions related to them is provided in Chapter 1. Chapter 2 provides fundamentals and details of experimental apparata, experimental protocol and calibration procedure. Chapter 3 & 4 provides extensive studies of stable non-crystalline toluene films of micrometer and nanometer thicknesses grown by vapor deposition at distinct deposition rates and temperatures and probed by Fast Scanning Calorimetry. Fast scanning calorimetry is shown to be extremely sensitive to the structure of the vapor-deposited phase and was used to characterize simultaneously its kinetic stability and its thermodynamic properties. According to our analysis, transformation of vapor -deposited samples of toluene during heating with rates in excess 100,000 K/s follows the zero-order kinetics. The transformation rate correlates strongly with the initial enthalpy of the sample, which increases with the deposition rate according to sub-linear law. Analysis of the transformation kinetics of vapor deposited toluene films of various thicknesses reveal a sudden increase in the transformation rate for films thinner than 250 nm. The change in kinetics correlates with the surface roughness scale of the substrate, which is interpreted as evidence for kinetic anisotropy of the samples. We also show that out-of-equilibrium relaxation kinetics and possibly the enthalpy of vapor-deposited (VD) films of toluene are distinct from those of ordinary supercooled (OS) phase even when the deposition takes place at temperatures above the glass softening (Tg). The implications of these findings for the formation mechanism and structure of vapor deposited stable glasses are discussed. Chapter 5 and 6 provide detailed Fast Scanning Calorimetry studies

  7. Hydration of thermally denatured lysozyme studied by sorption calorimetry and differential scanning calorimetry.

    PubMed

    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.

  8. Estimation of the nucleation rate by differential scanning calorimetry

    NASA Technical Reports Server (NTRS)

    Kelton, Kenneth F.

    1992-01-01

    A realistic computer model is presented for calculating the time-dependent volume fraction transformed during the devitrification of glasses, assuming the classical theory of nucleation and continuous growth. Time- and cluster-dependent nucleation rates are calculated by modeling directly the evolving cluster distribution. Statistical overlap in the volume fraction transformed is taken into account using the standard Johnson-Mehl-Avrami formalism. Devitrification behavior under isothermal and nonisothermal conditions is described. The model is used to demonstrate that the recent suggestion by Ray and Day (1990) that nonisothermal DSC studies can be used to determine the temperature for the peak nucleation rate, is qualitatively correct for lithium disilicate, the glass investigated.

  9. A study of ultra-strength polymer fibers via calorimetry

    NASA Astrophysics Data System (ADS)

    Egorov, V. M.; Boiko, Yu. M.; Marikhin, V. A.; Myasnikova, L. P.; Radovanova, E. I.

    2016-08-01

    Xerogel reactor powders and supramolecular polyethylene fibers with various degrees of hood have been studied via differential scanning calorimetry. A higher strength of laboratory fibers in comparison with industrial ones is found to be achieved due to a multistage band high-temperature hood that causes the thermodynamic parameters of supramolecular polymer structure.

  10. Release-rate calorimetry of multilayered materials for aircraft seats

    NASA Technical Reports Server (NTRS)

    Fewell, L. L.; Parker, J. A.; Duskin, F.; Speith, H.; Trabold, E.

    1980-01-01

    Multilayered samples of contemporary and improved fire-resistant aircraft seat materials were evaluated for their rates of heat release and smoke generation. Top layers with glass-fiber block cushion were evaluated to determine which materials, based on their minimum contributions to the total heat release of the multilayered assembly, may be added or deleted. The smoke and heat release rates of multilayered seat materials were then measured at heat fluxes of 1.5 and 3.5 W/cm2. Abrasion tests were conducted on the decorative fabric covering and slip sheet to ascertain service life and compatibility of layers

  11. Release-rate calorimetry of multilayered materials for aircraft seats

    NASA Technical Reports Server (NTRS)

    Fewell, L. L.; Parker, J. A.; Duskin, F.; Spieth, H.; Trabold, E.

    1980-01-01

    Multilayered samples of contemporary and improved fire-resistant aircraft seat materials (foam cushion, decorative fabric, slip sheet, fire-blocking layer, and cushion-reinforcement layer) were evaluated for their rates of heat release and smoke generation. Top layers (decorative fabric, slip sheet, fire blocking, and cushion reinforcement) with glass-fiber block cushion were evaluated to determine which materials, based on their minimum contributions to the total heat release of the multilayered assembly, may be added or deleted. Top layers exhibiting desirable burning profiles were combined with foam cushion materials. The smoke and heat-release rate of multilayered seat materials were then measured at heat fluxes of 1.5 and 3.5 W/sq cm. Choices of contact and silicon adhesives for bonding multilayered assemblies were based on flammability, burn and smoke generation, animal toxicity tests, and thermal gravimetric analysis.

  12. Mathematical model of cycad cones' thermogenic temperature responses: inverse calorimetry to estimate metabolic heating rates.

    PubMed

    Roemer, R B; Booth, D; Bhavsar, A A; Walter, G H; Terry, L I

    2012-12-21

    A mathematical model based on conservation of energy has been developed and used to simulate the temperature responses of cones of the Australian cycads Macrozamia lucida and Macrozamia. macleayi during their daily thermogenic cycle. These cones generate diel midday thermogenic temperature increases as large as 12 °C above ambient during their approximately two week pollination period. The cone temperature response model is shown to accurately predict the cones' temperatures over multiple days as based on simulations of experimental results from 28 thermogenic events from 3 different cones, each simulated for either 9 or 10 sequential days. The verified model is then used as the foundation of a new, parameter estimation based technique (termed inverse calorimetry) that estimates the cones' daily metabolic heating rates from temperature measurements alone. The inverse calorimetry technique's predictions of the major features of the cones' thermogenic metabolism compare favorably with the estimates from conventional respirometry (indirect calorimetry). Because the new technique uses only temperature measurements, and does not require measurements of oxygen consumption, it provides a simple, inexpensive and portable complement to conventional respirometry for estimating metabolic heating rates. It thus provides an additional tool to facilitate field and laboratory investigations of the bio-physics of thermogenic plants.

  13. Calorimetry Studies of Ammonia, Nitric Acid, and Ammonium Nitrate

    DTIC Science & Technology

    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

  14. Resistive Micromegas for sampling calorimetry, a study of charge-up effects

    NASA Astrophysics Data System (ADS)

    Chefdeville, M.; Karyotakis, Y.; Geralis, T.; Titov, M.

    2016-07-01

    Micromegas, as a proportional and compact gaseous detector, is well suited for sampling calorimetry. The limitation of occasional sparking has now been lifted by means of resistive electrodes but at the cost of current-dependent charge-up effects. These effects are studied in this contribution, with an emphasis on gain variations during operation at high particle rate and under heavy ionisation. Results are reproduced by a simple model of charging-up which will be used for detector design optimisation in the future.

  15. Isothermal titration calorimetry determination of individual rate constants of trypsin catalytic activity.

    PubMed

    Aguirre, César; Condado-Morales, Itzel; Olguin, Luis F; Costas, Miguel

    2015-06-15

    Determination of individual rate constants for enzyme-catalyzed reactions is central to the understanding of their mechanism of action and is commonly obtained by stopped-flow kinetic experiments. However, most natural substrates either do not fluoresce/absorb or lack a significant change in their spectra while reacting and, therefore, are frequently chemically modified to render adequate molecules for their spectroscopic detection. Here, isothermal titration calorimetry (ITC) was used to obtain Michaelis-Menten plots for the trypsin-catalyzed hydrolysis of several substrates at different temperatures (278-318K): four spectrophotometrically blind lysine and arginine N-free esters, one N-substituted arginine ester, and one amide. A global fitting of these data provided the individual rate constants and activation energies for the acylation and deacylation reactions, and the ratio of the formation and dissociation rates of the enzyme-substrate complex, leading also to the corresponding free energies of activation. The results indicate that for lysine and arginine N-free esters deacylation is the rate-limiting step, but for the N-substituted ester and the amide acylation is the slowest step. It is shown that ITC is able to produce quality kinetic data and is particularly well suited for those enzymatic reactions that cannot be measured by absorption or fluorescence spectroscopy.

  16. Kinetics of enzymatic high-solid hydrolysis of lignocellulosic biomass studied by calorimetry.

    PubMed

    Olsen, Søren N; Lumby, Erik; McFarland, Kc; Borch, Kim; Westh, Peter

    2011-03-01

    Enzymatic hydrolysis of high-solid biomass (>10% w/w dry mass) has become increasingly important as a key step in the production of second-generation bioethanol. To this end, development of quantitative real-time assays is desirable both for empirical optimization and for detailed kinetic analysis. In the current work, we have investigated the application of isothermal calorimetry to study the kinetics of enzymatic hydrolysis of two substrates (pretreated corn stover and Avicel) at high-solid contents (up to 29% w/w). It was found that the calorimetric heat flow provided a true measure of the hydrolysis rate with a detection limit of about 500 pmol glucose s(-1). Hence, calorimetry is shown to be a highly sensitive real-time method, applicable for high solids, and independent on the complexity of the substrate. Dose-response experiments with a typical cellulase cocktail enabled a multidimensional analysis of the interrelationships of enzyme load and the rate, time, and extent of the reaction. The results suggest that the hydrolysis rate of pretreated corn stover is limited initially by available attack points on the substrate surface (<10% conversion) but becomes proportional to enzyme dosage (excess of attack points) at later stages (>10% conversion). This kinetic profile is interpreted as an increase in polymer end concentration (substrate for CBH) as the hydrolysis progresses, probably due to EG activity in the enzyme cocktail. Finally, irreversible enzyme inactivation did not appear to be the source of reduced hydrolysis rate over time.

  17. Picowatt Resolution Calorimetry for Micro and Nanoscale Energy Transport Studies

    NASA Astrophysics Data System (ADS)

    Sadat, Seid H.

    Precise quantification of energy transport is key to obtaining insights into a wide range of phenomena across various disciplines including physics, chemistry, biology and engineering. This thesis describes technical advancements into heat-flow calorimetry which enable measurement of energy transport at micro and nanoscales with picowatt resolution. I have developed two types of microfabricated calorimeter devices and demonstrated single digit picowatt resolution at room temperature. Both devices incorporate two distinct features; an active area isolated by a thermal conductance (GTh) of less than 1 microW/K and a high resolution thermometer with temperature resolution (DeltaTres) in the micro kelvin regime. These features enable measurements of heat currents (q) with picowatt resolution (q= Th xDeltaTres). In the first device the active area is suspended via silicon nitride beams with excellent thermal isolation (~600 nW/K) and a bimaterial cantilever (BMC) thermometer with temperature resolution of ~6 microK. Taken together this design enabled calorimetric measurements with 4 pW resolution. In the second device, the BMC thermometry technique is replaced by a high-resolution resistance thermometry scheme. A detailed noise analysis of resistance thermometers, confirmed by experimental data, enabled me to correctly predict the resolution of different measurement schemes and propose techniques to achieve an order of magnitude improvement in the resolution of resistive thermometers. By incorporating resistance thermometers with temperature resolution of ~30 microK, combined with a thermal isolation of ~150 nW/K, I demonstrated an all-electrical calorimeter device with a resolution of ~ 5 pW. Finally, I used these calorimeters to study Near-Field Radiative Heat Transfer (NF-RHT). Using these devices, we studied--for the first time--the effect of film thickness on the NF-RHT between two dielectric surfaces. We showed that even a very thin film (~50 nm) of silicon

  18. Differential scanning calorimetry study--assessing the influence of composition of vegetable oils on oxidation.

    PubMed

    Qi, Baokun; Zhang, Qiaozhi; Sui, Xiaonan; Wang, Zhongjiang; Li, Yang; Jiang, Lianzhou

    2016-03-01

    The thermal oxidation of eight different vegetable oils was studied using differential scanning calorimetry (DSC) under non-isothermal conditions at five different heating rates (5, 7.5, 10, 12.5, and 15°C/min), in a temperature range of 100-400°C. For all oils, the activation energy (Ea) values at Tp were smaller than that at Ts and Ton. Among all the oils, refined palm oil (RPO) exhibited the highest Ea values, 126.06kJ/mol at Ts, 134.7kJ/mol at Ton, and 91.88kJ/mol at Tp. The Ea and reaction rate constant (k) values at Ts, Ton, and Tp were further correlated with oil compositions (fatty acids and triacylglycerols) using Pearson correlation analysis. The rate constant (k) and Ea of all oils exhibited varying correlations with FAs and TAGs, indicating that the thermal oxidation behaviors were affected by oil compositions.

  19. Fast Scanning Calorimetry study of non-equilibrium relaxation in fragile organic liquids

    NASA Astrophysics Data System (ADS)

    Sadtchenko, Vlad; Bhattacharya, Deepanjan; O'Reilly, Liam

    2013-03-01

    Fast scanning calorimetry (FSC), capable of heating rates in excess of 1000000 K/s, was combined with vapor deposition technique to investigate non-equilibrium relaxation in micrometer thick viscous liquid films of several organic compounds (e.g.2-ethyl-1-hexanol, Toluene, and 1-propanol) under high vacuum conditions. Rapid heating of samples, vapor deposited at temperatures above their standard glass softening transition (Tg), resulted in observable endotherms which onset temperatures were strongly dependent on heating rate and the deposition temperature. Furthermore, all of the studied compounds were characterized by distinct critical deposition temperatures at which observation of endotherm became impossible. Based on the results of these studies, we have developed a simple model which makes it possible to infer the equilibrium enthalpy relaxation times for liquids from FSC data. We will discuss implications of these studies for contemporary models of non-equilibrium relaxation in glasses and supercooled liquids. Supported by NSF Grant 1012692.

  20. Percent relative cumulative frequency analysis in indirect calorimetry: application to studies of transgenic mice.

    PubMed

    Riachi, Marc; Himms-Hagen, Jean; Harper, Mary-Ellen

    2004-12-01

    Indirect calorimetry is commonly used in research and clinical settings to assess characteristics of energy expenditure. Respiration chambers in indirect calorimetry allow measurements over long periods of time (e.g., hours to days) and thus the collection of large sets of data. Current methods of data analysis usually involve the extraction of only a selected small proportion of data, most commonly the data that reflects resting metabolic rate. Here, we describe a simple quantitative approach for the analysis of large data sets that is capable of detecting small differences in energy metabolism. We refer to it as the percent relative cumulative frequency (PRCF) approach and have applied it to the study of uncoupling protein-1 (UCP1) deficient and control mice. The approach involves sorting data in ascending order, calculating their cumulative frequency, and expressing the frequencies in the form of percentile curves. Results demonstrate the sensitivity of the PRCF approach for analyses of oxygen consumption (.VO2) as well as respiratory exchange ratio data. Statistical comparisons of PRCF curves are based on the 50th percentile values and curve slopes (H values). The application of the PRCF approach revealed that energy expenditure in UCP1-deficient mice housed and studied at room temperature (24 degrees C) is on average 10% lower (p < 0.0001) than in littermate controls. The gradual acclimation of mice to 12 degrees C caused a near-doubling of .VO2 in both UCP1-deficient and control mice. At this lower environmental temperature, there were no differences in .VO2 between groups. The latter is likely due to augmented shivering thermogenesis in UCP1-deficient mice compared with controls. With the increased availability of murine models of metabolic disease, indirect calorimetry is increasingly used, and the PRCF approach provides a novel and powerful means for data analysis.

  1. On the accuracy of instantaneous gas exchange rates, energy expenditure, and respiratory quotient calculations obtained in indirect whole room calorimetry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The molar balance equations of indirect calorimetry are treated from the point of view of cause-effect relationship where the gaseous exchange rates representing the unknown causes heed to be inferred from a known noisy effect – gaseous concentrations. Two methods of such inversion are analyzed. Th...

  2. Quantifying the rates of relaxation of binary mixtures of amorphous pharmaceuticals with isothermal calorimetry.

    PubMed

    Alem, Naziha; Beezer, Anthony E; Gaisford, Simon

    2010-10-31

    While the use of isothermal calorimetry to quantify the rate of relaxation of one-phase amorphous pharmaceuticals, through application of models, is well documented, the resolution of the models to detect and quantify relaxation in systems containing two independent amorphous phases is not known. Addressing this knowledge gap is the focus of this work. Two fitting models were tested; the Kohlrausch-Williams-Watts model (KWW) and the modified-stretch exponential (MSE). The ability of each model to resolve relaxation processes in binary systems was determined with simulated calorimetric data. It was found that as long as the relaxation time constants of the relaxation processes were with 10(3) of each other, the models could determine that two events were occurring and could quantify the correct reaction parameters of each. With greater differences in the time constants, the faster process always dominates the data and the resolving power of the models is lost. Real calorimetric data were then obtained for two binary amorphous systems (sucrose-lactose and sucrose-indomethacin mixtures). The relaxation behaviour of all the single components was characterised as they relaxed individually to provide reference data. The ability of the KWW model to recover the expected relaxation parameters for two component data was impaired because of their inherently noisy nature. The MSE model reasonably recovered the expected parameters for each component for the sucrose-indomethacin system but not for the sucrose-lactose system, which may indicate a possible interaction in that case.

  3. A Study of Concept Mapping as an Instructional Intervention in an Undergraduate General Chemistry Calorimetry Laboratory

    NASA Astrophysics Data System (ADS)

    Stroud, Mary W.

    This investigation, rooted in both chemistry and education, considers outcomes occurring in a small-scale study in which concept mapping was used as an instructional intervention in an undergraduate calorimetry laboratory. A quasi-experimental, multiple-methods approach was employed since the research questions posed in this study warranted the use of both qualitative and quantitative perspectives and evaluations. For the intervention group of students, a convenience sample, post-lab concept maps, written discussions, quiz responses and learning surveys were characterized and evaluated. Archived quiz responses for non-intervention students were also analyzed for comparison. Students uniquely constructed individual concept maps containing incorrect, conceptually correct and "scientifically thin" calorimetry characterizations. Students more greatly emphasized mathematical relationships and equations utilized during the calorimetry experiment; the meaning of calorimetry concepts was demonstrated to a lesser extent.

  4. Estimation of Activity Related Energy Expenditure and Resting Metabolic Rate in Freely Moving Mice from Indirect Calorimetry Data

    PubMed Central

    Van Klinken, Jan Bert; van den Berg, Sjoerd A. A.; Havekes, Louis M.; Willems Van Dijk, Ko

    2012-01-01

    Physical activity (PA) is a main determinant of total energy expenditure (TEE) and has been suggested to play a key role in body weight regulation. However, thus far it has been challenging to determine what part of the expended energy is due to activity in freely moving subjects. We developed a computational method to estimate activity related energy expenditure (AEE) and resting metabolic rate (RMR) in mice from activity and indirect calorimetry data. The method is based on penalised spline regression and takes the time dependency of the RMR into account. In addition, estimates of AEE and RMR are corrected for the regression dilution bias that results from inaccurate PA measurements. We evaluated the performance of our method based on 500 simulated metabolic chamber datasets and compared it to that of conventional methods. It was found that for a sample time of 10 minutes the penalised spline model estimated the time-dependent RMR with 1.7 times higher accuracy than the Kalman filter and with 2.7 times higher accuracy than linear regression. We assessed the applicability of our method on experimental data in a case study involving high fat diet fed male and female C57Bl/6J mice. We found that TEE in male mice was higher due to a difference in RMR while AEE levels were similar in both groups, even though female mice were more active. Interestingly, the higher activity did not result in a difference in AEE because female mice had a lower caloric cost of activity, which was likely due to their lower body weight. In conclusion, TEE decomposition by means of penalised spline regression provides robust estimates of the time-dependent AEE and RMR and can be applied to data generated with generic metabolic chamber and indirect calorimetry set-ups. PMID:22574139

  5. Calorimetry study of microwave absorption of some solid materials.

    PubMed

    He, Chun Lin; Ma, Shao Jian; Su, Xiu Juan; Chen, Yan Qing; Liang, Yu Shi

    2013-01-01

    In practice, the dielectric constant of a material varies the applied frequency the material composition, particle size, purity, temperature, physical state (solid or liquid), and moisture content. All of these parameters might change during processing, therefore, it is difficult to predict how well a material will absorb microwave energy in a given process. When the temperature is measured by a digital thermometer, it could not accurately reflect the true temperature of the bulk materials, especially for mixed materials. Thus, in this paper we measured the microwave absorption characteristics of different materials by calorimetry. The microwave power levels, irradiation times, and masses of the materials were varied. It was difficult to predict the microwave energy absorption characteristics of reagent-grade inorganic compounds based on their color, metallic cation, or water stoichiometry. CuO, MnO2, Fe3O4, and MnSO4 x H2O (Taishan) strongly absorbed microwave energy. Most of the remaining inorganic compounds were poor absorbers, with silica hardly absorbing any microwave energy. Carbon-based materials had significantly different microwave absorption characteristics. Activated carbon and coke were especially sensitive to microwaves, but different types of coal were poor absorbers. The jamesonite concentrate absorbed microwave energy strongly, while the zinc concentrate was a poor absorber.

  6. Influence of gamma radiation on potato starch gelatinization studied by differential scanning calorimetry

    NASA Astrophysics Data System (ADS)

    Cieśla, Krystyna; Eliasson, Ann-Charlotte

    2002-05-01

    The paper presents a study of the influence of the conditions applied during differential scanning calorimetry (DSC) measurements (concentration and heating rate) on the possible detection of the differences between gelatinization occurring in both non-irradiated and irradiated potato starch with a dose of 20 kGy. Differences in gelatinization of irradiated and non-irradiated potato starch during DSC analysis was attributed to the radiation induced destruction of crystalline ordering. This was confirmed by studies of the samples irradiated to very high doses (446 and 600 kGy), and by comparing with the effect of grinding. Changes of starch properties caused by radiodepolymerization—contrary to those caused by grinding—influences gelatinization behaviour much more than the WAXS crystallinity in solid state.

  7. The oxidation of aluminum at high temperature studied by Thermogravimetric Analysis and Differential Scanning Calorimetry.

    SciTech Connect

    Coker, Eric Nicholas

    2013-10-01

    The oxidation in air of high-purity Al foil was studied as a function of temperature using Thermogravimetric Analysis with Differential Scanning Calorimetry (TGA/DSC). The rate and/or extent of oxidation was found to be a non-linear function of the temperature. Between 650 and 750 ÀC very little oxidation took place; at 850 ÀC oxidation occurred after an induction period, while at 950 ÀC oxidation occurred without an induction period. At oxidation temperatures between 1050 and 1150 ÀC rapid passivation of the surface of the aluminum foil occurred, while at 1250 ÀC and above, an initial rapid mass increase was observed, followed by a more gradual increase in mass. The initial rapid increase was accompanied by a significant exotherm. Cross-sections of oxidized specimens were characterized by scanning electron microscopy (SEM); the observed alumina skin thicknesses correlated qualitatively with the observed mass increases.

  8. Dietary effects on resting metabolic rate in C57BL/6 mice are differentially detected by indirect (O2/CO2 respirometry) and direct calorimetry

    PubMed Central

    Burnett, Colin M.L.; Grobe, Justin L.

    2014-01-01

    Resting metabolic rate (RMR) studies frequently involve genetically-manipulated mice and high fat diets (HFD). We hypothesize that the use of inadequate methods impedes the identification of novel regulators of RMR. This idea was tested by simultaneously measuring RMR by direct calorimetry and respirometry in C57BL/6J mice fed chow, 45% HFD, and then returned to chow. Comparing results during chow feeding uncovered an underestimation of RMR by respirometry (0.010 ± 0.001 kcal/h, P < 0.05), which is equivalent in magnitude to ∼2% of total daily caloric turnover. RMR during 45% HFD feeding was increased by respirometry (+0.013 ± 0.003 kcal/h, P < 0.05), but not direct calorimetry (+0.001 ± 0.002 kcal/h). Both methods indicated that return to chow reduced RMR compared to HFD, though direct calorimetry indicated a reduction below the initial chow fed state (−0.019 ± 0.004 kcal/h versus baseline, P < 0.05) that was not detected by respirometry (−0.003 ± 0.002 kcal/h versus baseline). These results highlight method-specific interpretations of the effects of dietary interventions upon RMR in mice, and prompt the reevaluation of preclinical screening methods used to identify novel RMR modulators. PMID:24944905

  9. Test beam studies of silicon timing for use in calorimetry

    NASA Astrophysics Data System (ADS)

    Apresyan, A.; Bolla, G.; Bornheim, A.; Kim, H.; Los, S.; Pena, C.; Ramberg, E.; Ronzhin, A.; Spiropulu, M.; Xie, S.

    2016-07-01

    The high luminosity upgrade of the Large Hadron Collider (HL-LHC) at CERN is expected to provide instantaneous luminosities of 5 ×1034cm-2s-1 . The high luminosities expected at the HL-LHC will be accompanied by a factor of 5-10 more pileup compared with LHC conditions in 2015, further increasing the challenge for particle identification and event reconstruction. Precision timing allows us to extend calorimetric measurements into such a high density environment by subtracting the energy deposits from pileup interactions. Calorimeters employing silicon as the active component have recently become a viable choice for the HL-LHC and future collider experiments which face very high radiation environments. In this paper, we present studies of basic calorimetric and precision timing measurements using a prototype composed of tungsten absorber and silicon sensor as the active medium. We show that for the bulk of electromagnetic showers induced by electrons in the range of 20-30 GeV, we can achieve time resolutions better than 25 ps per single pad sensor.

  10. Test beam studies of silicon timing for use in calorimetry

    SciTech Connect

    Apresyan, A.; Bolla, G.; Bornheim, A.; Kim, H.; Los, S.; Pena, C.; Ramberg, E.; Ronzhin, A.; Spiropulu, M.; Xie, S.

    2016-04-12

    The high luminosity upgrade of the Large Hadron Collider (HL-LHC) at CERN is expected to provide instantaneous luminosities of 5 X 1034 cm–2 s–1. The high luminosities expected at the HL-LHC will be accompanied by a factor of 5 to 10 more pileup compared with LHC conditions in 2015, causing general confusion for particle identification and event reconstruction. Precision timing allows to extend calorimetric measurements into such a high density environment by subtracting the energy deposits from pileup interactions. Calorimeters employing silicon as the active component have recently become a popular choice for the HL-LHC and future collider experiments which face very high radiation environments. In this article, we present studies of basic calorimetric and precision timing measurements using a prototype composed of tungsten absorber and silicon sensor as the active medium. Lastly, we show that for the bulk of electromagnetic showers induced by electrons in the range of 20 GeV to 30 GeV, we can achieve time resolutions better than 25 ps per single pad sensor.

  11. Test beam studies of silicon timing for use in calorimetry

    DOE PAGES

    Apresyan, A.; Bolla, G.; Bornheim, A.; ...

    2016-04-12

    The high luminosity upgrade of the Large Hadron Collider (HL-LHC) at CERN is expected to provide instantaneous luminosities of 5 X 1034 cm–2 s–1. The high luminosities expected at the HL-LHC will be accompanied by a factor of 5 to 10 more pileup compared with LHC conditions in 2015, causing general confusion for particle identification and event reconstruction. Precision timing allows to extend calorimetric measurements into such a high density environment by subtracting the energy deposits from pileup interactions. Calorimeters employing silicon as the active component have recently become a popular choice for the HL-LHC and future collider experiments whichmore » face very high radiation environments. In this article, we present studies of basic calorimetric and precision timing measurements using a prototype composed of tungsten absorber and silicon sensor as the active medium. Lastly, we show that for the bulk of electromagnetic showers induced by electrons in the range of 20 GeV to 30 GeV, we can achieve time resolutions better than 25 ps per single pad sensor.« less

  12. Exploration of Energy Metabolism in the Mouse Using Indirect Calorimetry: Measurement of Daily Energy Expenditure (DEE) and Basal Metabolic Rate (BMR).

    PubMed

    Meyer, Carola W; Reitmeir, Peter; Tschöp, Matthias H

    2015-09-01

    Current comprehensive mouse metabolic phenotyping involves studying energy balance in cohorts of mice via indirect calorimetry, which determines heat release from changes in respiratory air composition. Here, we describe the measurement of daily energy expenditure (DEE) and basal metabolic rate (BMR) in mice. These well-defined metabolic descriptors serve as meaningful first-line read-outs for metabolic phenotyping and should be reported when exploring energy expenditure in mice. For further guidance, the issue of appropriate sample sizes and the frequency of sampling of metabolic measurements is also discussed.

  13. 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…

  14. CALORIMETRY OF GRB 030329: SIMULTANEOUS MODEL FITTING TO THE BROADBAND RADIO AFTERGLOW AND THE OBSERVED IMAGE EXPANSION RATE

    SciTech Connect

    Mesler, Robert A.; Pihlstroem, Ylva M.

    2013-09-01

    We perform calorimetry on the bright gamma-ray burst GRB 030329 by fitting simultaneously the broadband radio afterglow and the observed afterglow image size to a semi-analytic MHD and afterglow emission model. Our semi-analytic method is valid in both the relativistic and non-relativistic regimes, and incorporates a model of the interstellar scintillation that substantially effects the broadband afterglow below 10 GHz. The model is fitted to archival measurements of the afterglow flux from 1 day to 8.3 yr after the burst. Values for the initial burst parameters are determined and the nature of the circumburst medium is explored. Additionally, direct measurements of the lateral expansion rate of the radio afterglow image size allow us to estimate the initial Lorentz factor of the jet.

  15. Study of the KNO3-Al2O3 system by differential scanning calorimetry

    NASA Astrophysics Data System (ADS)

    Amirov, A. M.; Gafurov, M. M.; Rabadanov, K. Sh.

    2016-09-01

    The structural and the thermodynamic properties of potassium nitrate KNO3 and its composites with nanosized aluminum oxide Al2O3 have been studied by differential scanning calorimetry. It has been found that an amorphous phase forms in composites (1- x)KNO3- x Al2O3. The thermal effect corresponding to this phase has been observed at 316°C. It has been found that the phase transition heats of potassium nitrate decreased as the aluminum oxide fraction increased.

  16. Internal short circuit and accelerated rate calorimetry tests of lithium-ion cells: Considerations for methane-air intrinsic safety and explosion proof/flameproof protection methods

    PubMed Central

    Dubaniewicz, Thomas H.; DuCarme, Joseph P.

    2016-01-01

    Researchers with the National Institute for Occupational Safety and Health (NIOSH) studied the potential for lithium-ion cell thermal runaway from an internal short circuit in equipment for use in underground coal mines. In this third phase of the study, researchers compared plastic wedge crush-induced internal short circuit tests of selected lithium-ion cells within methane (CH4)-air mixtures with accelerated rate calorimetry tests of similar cells. Plastic wedge crush test results with metal oxide lithium-ion cells extracted from intrinsically safe evaluated equipment were mixed, with one cell model igniting the chamber atmosphere while another cell model did not. The two cells models exhibited different internal short circuit behaviors. A lithium iron phosphate (LiFePO4) cell model was tolerant to crush-induced internal short circuits within CH4-air, tested under manufacturer recommended charging conditions. Accelerating rate calorimetry tests with similar cells within a nitrogen purged 353-mL chamber produced ignitions that exceeded explosion proof and flameproof enclosure minimum internal pressure design criteria. Ignition pressures within a 20-L chamber with 6.5% CH4-air were relatively low, with much larger head space volume and less adiabatic test conditions. The literature indicates that sizeable lithium thionyl chloride (LiSOCl2) primary (non rechargeable) cell ignitions can be especially violent and toxic. Because ignition of an explosive atmosphere is expected within explosion proof or flameproof enclosures, there is a need to consider the potential for an internal explosive atmosphere ignition in combination with a lithium or lithium-ion battery thermal runaway process, and the resulting effects on the enclosure. PMID:27695201

  17. Internal short circuit and accelerated rate calorimetry tests of lithium-ion cells: Considerations for methane-air intrinsic safety and explosion proof/flameproof protection methods.

    PubMed

    Dubaniewicz, Thomas H; DuCarme, Joseph P

    2016-09-01

    Researchers with the National Institute for Occupational Safety and Health (NIOSH) studied the potential for lithium-ion cell thermal runaway from an internal short circuit in equipment for use in underground coal mines. In this third phase of the study, researchers compared plastic wedge crush-induced internal short circuit tests of selected lithium-ion cells within methane (CH4)-air mixtures with accelerated rate calorimetry tests of similar cells. Plastic wedge crush test results with metal oxide lithium-ion cells extracted from intrinsically safe evaluated equipment were mixed, with one cell model igniting the chamber atmosphere while another cell model did not. The two cells models exhibited different internal short circuit behaviors. A lithium iron phosphate (LiFePO4) cell model was tolerant to crush-induced internal short circuits within CH4-air, tested under manufacturer recommended charging conditions. Accelerating rate calorimetry tests with similar cells within a nitrogen purged 353-mL chamber produced ignitions that exceeded explosion proof and flameproof enclosure minimum internal pressure design criteria. Ignition pressures within a 20-L chamber with 6.5% CH4-air were relatively low, with much larger head space volume and less adiabatic test conditions. The literature indicates that sizeable lithium thionyl chloride (LiSOCl2) primary (non rechargeable) cell ignitions can be especially violent and toxic. Because ignition of an explosive atmosphere is expected within explosion proof or flameproof enclosures, there is a need to consider the potential for an internal explosive atmosphere ignition in combination with a lithium or lithium-ion battery thermal runaway process, and the resulting effects on the enclosure.

  18. Effect of L-Carnitine in Patients With Liver Cirrhosis on Energy Metabolism Using Indirect Calorimetry: A Pilot Study

    PubMed Central

    Sakai, Yoshiyuki; Nishikawa, Hiroki; Enomoto, Hirayuki; Yoh, Kazunori; Iwata, Yoshinori; Hasegawa, Kunihiro; Nakano, Chikage; Kishino, Kyohei; Shimono, Yoshihiro; Takata, Ryo; Nishimura, Takashi; Aizawa, Nobuhiro; Ikeda, Naoto; Takashima, Tomoyuki; Ishii, Akio; Iijima, Hiroko; Nishiguchi, Shuhei

    2016-01-01

    Background L-carnitine supplementation has been suggested to show several favorable effects on patients with liver cirrhosis (LC). However, there have been no reports regarding the effect of L-carnitine on energy metabolism in patients with LC using indirect calorimetry which is a well-established method for assessing the degree of liver malnutrition. We examined the effect of L-carnitine in patients with LC on energy metabolism using indirect calorimetry. Methods A total of 13 LC patients who are scheduled to be treated with L-carnitine (1,800 mg/day) were analyzed in this study. None of the patients previously received L-carnitine. An evaluation of the nutritional status was performed at the initiation of L-carnitine therapy and after 4 weeks of L-carnitine therapy. We evaluated the effect of L-carnitine on the nutritional status and energy metabolism by comparing various clinical variables at these two time points. In addition, the changes in the nutritional status of the patients were also evaluated using indirect calorimetry. Results After 4 weeks of L-carnitine treatment, for all cases, the mean substrate oxidation rates of carbohydrate (%C) increased from 37.6% to 48.2%, the mean substrate oxidation rates of fat (%F) decreased from 40.2% to 31.9% and the mean substrate oxidation rates of protein (%P) decreased from 22.2% to 19.9%. In a subgroup analysis of patients with baseline non-protein respiratory quotient (npRQ) < 0.85, the mean %C increased from 15.3% to 34.2%, the mean %F decreased from 59.9% to 45.1%, and the mean %P decreased from 24.8% to 20.6%. After 4 weeks of L-carnitine treatment, for all cases (n = 13), the mean value of npRQ increased in comparison with the baseline levels, although the difference was not significant (0.868 ± 0.060 vs. 0.838 ± 0.097, P = 0.19). Conversely, in patients with baseline npRQ < 0.85, the npRQ value significantly increased after 4 weeks treatment of L-carnitine compared with the baseline levels (0.827 ± 0.030 vs

  19. Applications of isothermal titration calorimetry in biophysical studies of G-quadruplexes.

    PubMed

    Pagano, Bruno; Mattia, Carlo Andrea; Giancola, Concetta

    2009-07-02

    G-quadruplexes are higher-order nucleic acids structures formed by G-rich sequences that are stabilized by tetrads of hydrogen-bonded guanine bases. Recently, there has been growing interest in the study of G-quadruplexes because of their possible involvement in many biological processes. Isothermal titration calorimetry (ITC) has been proven to be a useful tool to study the energetic aspects of G-quadruplex interactions. Particularly, ITC has been applied many times to determine the thermodynamic properties of drug-quadruplex interactions to screening among various drugs and to address drug design. In the present review, we will focus on the ITC studies of G-quadruplex structures and their interaction with proteins and drugs and the most significant results will be discussed.

  20. Molecular mobility studies on the amorphous state of disaccharides. I-thermally stimulated currents and differential scanning calorimetry.

    PubMed

    Pinto, Susana S; Diogo, Hermínio P; Nunes, Teresa G; Moura Ramos, Joaquim J

    2010-08-16

    The relaxational processes in amorphous solid gentiobiose and cellobiose are studied by thermally stimulated depolarization currents (TSDC) in the temperature region from 108K up to 423K. The slow molecular mobility was characterized in the crystal and in the glassy state. The features of different motional components of the secondary relaxation have been monitored as a function of time as the glass structurally relaxes on aging. It is concluded that some modes of motion of this mobility are aging independent, while others are affected by aging. The value of the steepness index or fragility (T(g)-normalized temperature dependence of the relaxation time) was obtained by differential scanning calorimetry (DSC) from the analysis of the scanning rate dependency of T(g).

  1. 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.

  2. Study of Polymer Glasses by Modulated Differential Scanning Calorimetry in the Undergraduate Physical Chemistry Laboratory

    NASA Astrophysics Data System (ADS)

    Folmer, J. C. W.; Franzen, Stefan

    2003-07-01

    Recent technological advances in thermal analysis present educational opportunities. In particular, modulated differential scanning calorimetry (MDSC) can be used to contrast reversing and nonreversing processes in practical laboratory experiments. The introduction of these concepts elucidates the relationship between experimental timescales and reversibility. The latter is a key concept of undergraduate thermodynamics theory that deserves reinforcement. In this paper, the theory and application of MDSC to problems of current interest is outlined with special emphasis on the contrast between crystallization and vitrification. Glass formation deserves greater emphasis in the undergraduate curriculum. Glass transitions are increasingly recognized as an important aspect of materials properties and dynamics in fields ranging from polymer science to protein folding. The example chosen for study is a comparison of polyethylene glycol and atactic polypropylene glycol. The experiment is easily performed in a typical three-hour lab session.

  3. The complexity of condensed tannin binding to bovine serum albumin--An isothermal titration calorimetry study.

    PubMed

    Kilmister, Rachel L; Faulkner, Peta; Downey, Mark O; Darby, Samuel J; Falconer, Robert J

    2016-01-01

    Isothermal titration calorimetry was applied to study the binding of purified proanthocyanidin oligomers to bovine serum albumin (BSA). The molecular weight of the proanthocyanidin oligomer had a major impact on its binding to BSA. The calculated change in enthalpy (ΔH) and association constant (Ka) became greater as the oligomer size increased then plateaued at the heptameric oligomer. These results support a model for precipitation of proteins by proanthocyanidin where increased oligomer size enhanced the opportunity for cross linkages between proteins ultimately forming sediment-able complexes. The authors suggest tannin binding to proteins is opportunistic and involves multiple sites, each with a different Ka and ΔH of binding. The ΔH of binding comprises both an endothermic hydrophobic interaction and exothermic hydrogen bond component. This suggests the calculated entropy value (ΔS) for tannin-protein interactions is subject to a systematic error and should be interpreted with caution.

  4. Quantum Calorimetry

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

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

  5. Validation and recovery rates of an indirect calorimetry headbox system used to measure heat production of cattle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A headbox system was constructed at the University of Nebraska-Lincoln to determine heat production from dairy cattle using indirect calorimetry. The system was designed for use in a tie-stall barn to allow the animal to be comfortable and was mounted on wheels to transport between animals between s...

  6. Dynamics and topochemistry of the thermal formation of cadmium telluride from the constituent elements: A differential scanning calorimetry study

    SciTech Connect

    Wenyuan Lin; Mishra, K.K.; Segal, R.; Rajeshwar, K. )

    1991-05-16

    The kinetics and topochemical details of the condensed-phase Cd + Te = CdTe reaction system were studied by differential scanning calorimetry (DSC) in conjunction with scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX). Measurable rates in this reaction system were sustained only after fusion of the Cd reactant particles. The exothermic reaction heat-release profiles were analyzed by DSC as a function of the scan rate. A new kinetics measurement protocol was developed that combines isothermal DSC operation with dynamic heat-cool probe' cycles for the Cd content of the reaction mixture. When the starting reaction components were in fine powder form, the reaction rate initially was very rapid, leading to the formation of a passivating CdTe outer skin. The activation energy of 7.2 {plus minus} 0.8 kJ/mol measured from these data was consistent with a model involving physical diffusion of the reactants through the CdTe layer as the rate-determining step. Accordingly, the use of larger size Te reactant particles in the 575-875-{mu}m range enabled a quantitative fit of the kinetics data to a contracting sphere model. Finally, the use of SEM and EDX permitted unambiguous verification of the proposed model for the reaction topochemistry.

  7. Differential scanning calorimetry studies of intraembryonic freezing and cryoprotectant penetration in zebrafish (Danio rerio) embryos.

    PubMed

    Liu, X H; Zhang, T; Rawson, D M

    2001-08-01

    Nucleation temperatures of intraembryonic water and cryoprotectant penetration in zebrafish embryos were studied using differential scanning calorimetry. The effects of embryo developmental stage, dechorionation, partial removal of yolk, cooling rate, and cryoprotectant treatment on the temperatures of intraembryonic freezing were investigated. Embryo stages were found to have a significant effect on the nucleation temperatures of intact embryos. Freeze onset temperatures of -11.9 +/- 1.5, -15.6 +/- 0.3, and -20.5 +/- 0.1 degrees C were obtained for intact embryos at 6-somite, prim-6, and high-pec stages, respectively. After dechorionation, the freeze onset temperatures of intraembryonic water shifted to significantly lower temperatures, being -23.5 +/- 0.8, -18.7 +/- 0.7, -24.9 +/- 0.8 degrees C for 6-somite, prim-6, and high-pec stages, respectively. Yolk-reduced high-pec stage embryos showed significantly lower nucleation temperatures with an average onset at -27.9 +/- 0.4 degrees C. The effect of cryoprotectant treatment on the nucleation temperatures of intraembryonic water varies among different embryo stages and different cryoprotectants. Thirty-minute treatment with 2 M methanol significantly decreased the nucleation temperatures of dechorionated 6-somite embryos whilst no temperature decrease was observed for prim-6 or yolk-reduced high-pec embryos. Thirty-minute exposure to 1 M propylene glycol did not significantly affect the nucleation temperatures of dechorionated 6-somite, prim-6, or yolk-reduced high-pec embryos. In order to increase the permeability of embryos to cryoprotectants, the yolk sacs of dechorionated embryos at 6-somite or prim-6 embryos were punctured with a sharp micro-needle before exposure to cryoprotectants. The punctured prim-6 embryos showed significantly lower temperatures of intraembryonic freezing after 30 min of exposure to 2 M methanol following the multi-punctures. The nucleation temperatures of punctured 6-somite or prim-6

  8. Binding of copper to lysozyme: Spectroscopic, isothermal titration calorimetry and molecular docking studies

    NASA Astrophysics Data System (ADS)

    Jing, Mingyang; Song, Wei; Liu, Rutao

    2016-07-01

    Although copper is essential to all living organisms, its potential toxicity to human health have aroused wide concerns. Previous studies have reported copper could alter physical properties of lysozyme. The direct binding of copper with lysozyme might induce the conformational and functional changes of lysozyme and then influence the body's resistance to bacterial attack. To better understand the potential toxicity and toxic mechanisms of copper, the interaction of copper with lysozyme was investigated by biophysical methods including multi-spectroscopic measurements, isothermal titration calorimetry (ITC), molecular docking study and enzyme activity assay. Multi-spectroscopic measurements proved that copper quenched the intrinsic fluorescence of lysozyme in a static process accompanied by complex formation and conformational changes. The ITC results indicated that the binding interaction was a spontaneous process with approximately three thermodynamical binding sites at 298 K and the hydrophobic force is the predominant driven force. The enzyme activity was obviously inhibited by the addition of copper with catalytic residues Glu 35 and Asp 52 locating at the binding sites. This study helps to elucidate the molecular mechanism of the interaction between copper and lysozyme and provides reference for toxicological studies of copper.

  9. Calorimetry for the SSC

    SciTech Connect

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

    1984-01-01

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

  10. Spectroscopy, calorimetry and molecular simulation studies on the interaction of catalase with copper ion.

    PubMed

    Hao, Fang; Jing, Mingyang; Zhao, Xingchen; Liu, Rutao

    2015-02-01

    In this research, the binding mechanism of Cu(2+) to bovine liver catalase (BLC) was studied by fluorescence spectroscopy, ultraviolet-visible (UV-vis) absorption spectroscopy, circular dichroism (CD) spectroscopy, isothermal titration calorimetry (ITC) and molecular docking methods. The cellar experiment was firstly carried out to investigate the inhibition effect of catalase. During the fluorescence quenching study, after correcting the inner filter effect (IFE), the fluorescence of BLC was found to be quenched by Cu(2+). The quenching mechanism was determined by fluorescence lifetime measurement, and was confirmed to be the dynamic mode. The secondary structure content of BLC was changed by the addition of Cu(2+), as revealed by UV-vis absorption and CD spectra, which further induces the decrease in BLC activity. Molecular simulation study indicates that Cu(2+) is located between two β-sheets and two random coils of BLC near to the heme group, and interacts with His 74 and Ser 113 residues near a hydrophilic area. The decrease of α-helix and the binding of His 74 are considered to be the major reason for the inhibition of BLC activity caused by Cu(2+). The ITC results indicate that the binding stoichiometry of Cu(2+) to catalase is 11.4. Moreover, the binding of Cu(2+) to BLC destroyed H-bonds, which was confirmed by the CD result.

  11. Thermal stability of Phaseolus vulgaris leucoagglutinin: a differential scanning calorimetry study.

    PubMed

    Biswas, Shyamasri; Kayastha, Arvind M

    2002-09-30

    Phaseolus vulgaris phytohemagglutinin L is a homotetrameric-leucoagglutinating seed lectin. Its three-dimensional structure shows similarity with other members of the legume lectin family. The tetrameric form of this lectin is pH dependent. Gel filtration results showed that the protein exists in its dimeric state at pH 2.5 and as a tetramer at pH 7.2. Contrary to earlier reports on legume lectins that possess canonical dimers, thermal denaturation studies show that the refolding of phytohemagglutinin L at neutral pH is irreversible. Differential scanning calorimetry (DSC) was used to study the denaturation of this lectin as a function of pH that ranged from 2.0 to 3.0. The lectin was found to be extremely thermostable with a transition temperature around 82 degrees C and above 100 degrees C at pH 2.5 and 7.2, respectively. The ratio of calorimetric to vant Hoff enthalpy could not be calculated because of its irreversible-folding behavior. However, from the DSC data, it was discovered that the protein remains in its compact-folded state, even at pH 2.3, with the onset of denaturation occurring at 60 degrees C.

  12. Study of temperature dependent zirconium silicide phases in Zr/Si structure by differential scanning calorimetry

    NASA Astrophysics Data System (ADS)

    Faruque, Sk Abdul Kader Md; Ranjan Bhattachryya, Satya; Sinha, Anil Kumar; Chakraborty, Supratic

    2016-02-01

    The differential scanning calorimetry (DSC) technique is employed to study the formation of different silicide compounds of Zr thin-film deposited on a 100 μm-thick Si (1 0 0) substrate by dc sputtering. A detailed analysis shows that silicide layers start growing at  ∼246 °C that changes to stable ZrSi2 at 627 °C via some compounds with different stoichiometric ratios of Zr and Si. It is further observed that oxygen starts reacting with Zr at  ∼540 °C but a stoichiometric ZrO2 film is formed after complete consumption of Zr metal at 857 °C. A further rise in temperature changes a part of ZrSi2 to Zr-Silicate. The synchrotron radiation-based grazing incidence x-ray diffraction and x-ray photoelectron spectroscopy studies also corroborate the above findings. Atomic force microscopy is also carried out on the samples. It is evident from the observations that an intermixing and nucleation of Zr and Si occur at lower temperature prior to the formation of the interfacial silicate layer. Zr-Silicate formation takes place only at a higher temperature.

  13. Application of isothermal titration calorimetry as a tool to study natural product interactions.

    PubMed

    Callies, O; Hernández Daranas, A

    2016-07-28

    Covering: up to February 2015Over the past twenty-five years, isothermal titration calorimetry (ITC) has become a potent tool for the study a great variety of molecular interactions. This technique is able to provide a complete thermodynamic profile of an interaction process in a single experiment, with a series of advantages in comparison to other comparable techniques, such as less amount of sample or no need of chemical modification or labelling. It is thus not surprising that ITC has been applied to study the manifold types of interactions of natural products to get new insights into the molecular key factors implied in the complexation process of this type of compounds. This review provides an overview over the applications of ITC as a potent tool to investigate interactions of natural products with proteins, nucleic acids, oligosaccharides, and other types of receptors. The examples have been selected depending on the impact that this technique had during the investigation and revision of the interactions involved in the bioactivity of a compound, lead optimization or technical applications.

  14. Systematic differential scanning calorimetry studies of the cure of carbon fiber - epoxy composite prepregs

    SciTech Connect

    Walkup, C.M.; Morgan, R.J.; Hoheisel, T.H.

    1983-11-01

    High performance C fiber-epoxy composite laminates are fabricated from uncured C fiber-epoxy prepreg material. Diaminodiphenyl sulfone (DDS) cured tetraglycidyl 4,4' diaminodiphenyl methane (TGDDM) epoxies, whose cure reactions are accelerated by BF/sub 3/:amine catalysts, are the most common composite matrices utilized in these high performance composites. To process reproducible composites requires an understanding of the cure reactions and how these reactions are modified by the BF/sub 3/:amine catalysts. In this paper we report systematic differential scanning calorimetry (DSC) studies of the constituents of BF/sub 3/:NH/sub 2/C/sub 2/H/sub 5/ catalyzed TGDDM-DDS epoxies and their mixtures; the effect of BF/sub 3/:NH/sub 2/C/sub 2/H/sub 5/ concentration on the cure reactions; the nature of the catalyzed cure reactions and the environmental sensitivity of the catalyst. DSC studies are also reported on the cure reaction characteristics and environmental sensitivity of commercial C fiber-TGDDM-DDS epoxy prepregs.

  15. Differential scanning calorimetry as a screening technique in compatibility studies of DHEA extended release formulations.

    PubMed

    Mora, P Corvi; Cirri, M; Mura, P

    2006-09-11

    Differential scanning calorimetry (DSC) was used as a screening technique for assessing the compatibility of DHEA as ternary complex with alpha-cyclodextrin and glycine (c-DHEA) with some excipients suitable for preparation of sustained-release matrix tablets by direct compression. The effect of sample mechanical treatment due to the compression process was also evaluated. In order to investigate the possible interactions between the components, the DSC curves of c-DHEA and each selected excipient were compared with those of their 1:1 w/w physical mixtures, before and after compression, in order to evaluate any possible solid state modification. FT-IR spectroscopy and X-ray powder diffractometry were used as complementary techniques to adequately implement and assist in interpretation of the DSC results. On the basis of DSC results, c-DHEA was found to be compatible with xanthan gum, hydroxypropylmethylcellulose, sodium starch glycolate (Explotab), polyvinylacetate-polyvinylpirrolidone (Kollidon SR) and sodium chloride. Some drug-excipient interaction was observed with dextrate hydrate (Emdex), mannitol and Magnesium stearate. Finally, the behaviour of the complete formulation, in the presence of all the excipients selected by means of the compatibility study, was investigated, in order to verify the absence of reciprocal interactions among the components.

  16. Thermodynamic Study on the Protonation Reactions of Glyphosate in Aqueous Solution: Potentiometry, Calorimetry and NMR spectroscopy.

    PubMed

    Liu, Bijun; Dong, Lan; Yu, Qianhong; Li, Xingliang; Wu, Fengchang; Tan, Zhaoyi; Luo, Shunzhong

    2016-03-10

    Glyphosate [N-(phosphonomethyl)glycine] has been described as the ideal herbicide because of its unique properties. There is some conflicting information concerning the structures and conformations involved in the protonation process of glyphosate. Protonation may influence the chemical and physical properties of glyphosate, modifying its structure and the chemical processes in which it is involved. To better understand the species in solution associated with changes in pH, thermodynamic study (potentiometry, calorimetry and NMR spectroscopy) about the protonation pathway of glyphosate is performed. Experimental results confirmed that the order of successive protonation sites of totally deprotonated glyphosate is phosphonate oxygen, amino nitrogen, and finally carboxylate oxygen. This trend is in agreement with the most recent theoretical work in the literature on the subject (J. Phys. Chem. A 2015, 119, 5241-5249). The result is important because it confirms that the protonated site of glyphosate in pH range 7-8, is not on the amino but on the phosphonate group instead. This corrected information can improve the understanding of the glyphosate chemical and biochemical action.

  17. Phase Polymorphism of [Mn(DMSO)6](BF4)2 Studied by Differential Scanning Calorimetry

    NASA Astrophysics Data System (ADS)

    Migdał-Mikuli, Anna; Skoczylas, Łukasz

    2008-12-01

    The tetrafluoroborate of hexadimethylsulfoxidemanganese(II) was synthesized and studied by differential scanning calorimetry. Five solid phases of [Mn(DMSO)6](BF4)2 were revealed. Specifically, four phase transitions of the first order were detected between the following solid phases: stable KIb↔stable KIa at TC4 = 215 K; metastable KIII↔overcooled K0 at TC3 = 354 K; metastable KII↔overcooled K0 at TC2 =377 K; stable KIa→stable K0 at TC1 =385 K. [Mn(DMSO)6](BF4)2 starts to decompose at 400 K with a loss of one DMSO molecule per formula unit and forms [Mn(DMSO)5](BF4)2 which next decomposes in one step to MnF2 at the temperature range of 460 - 583 K. From the entropy changes it can be concluded that the phases K0 and metastable KII are orientationally dynamically disordered (ODDIC) crystals. The stable phases KIb and KIa are ordered solid phases.

  18. The interaction of phenolic acids with Fe(III) in the presence of citrate as studied by isothermal titration calorimetry.

    PubMed

    Yang, Senpei; Bai, Guangling; Chen, Lingli; Shen, Qun; Diao, Xianmin; Zhao, Guanghua

    2014-08-15

    Under physiological conditions, exogenous chelators such as polyphenols might interact with non-protein bound ferric complexes, such as Fe(III)-citrate. Additionally, Fe(III) and citrate are widely distributed in various fruits and vegetables which are also rich in phenolic acids. In this study, we focus on the interaction between phenolic acids (gallic acid, methyl gallate and protocatechuic acid) and Fe(III) in the presence of excessive citrate by isothermal titration calorimetry (ITC) for thermodynamic studies, and stopped-flow absorption spectrometry for fast kinetic studies. Results reveal that all of these three phenolic acids can bind to the Fe(III) with the same stoichiometry (3:1). Moreover, the binding constants of these three compounds with Fe(III) are greatly dependent on ligand structure, and are much higher than that of Fe(III)-citrate. Based on their stoichiometry and superhigh binding constants, it is most likely that these three phenolic acids can displace the citrate to bind with one iron(III) ion to form a stable octahedral geometric structure, albeit at different rates. These findings shed light on the interaction between phenolic acids and Fe(III) in the presence of citrate under either physiological conditions or in a food system.

  19. Interaction between vitamin D 2 and magnesium in liposomes: Differential scanning calorimetry and FTIR spectroscopy studies

    NASA Astrophysics Data System (ADS)

    Toyran, Neslihan; Severcan, Feride

    2007-08-01

    Magnesium (Mg 2+) ion is of great importance in physiology by its intervention in 300 enzymatic systems, its role in membrane structure, its function in neuromuscular excitability and vitamin D metabolism and/or action. In the present study, the interaction of Mg 2+, at low (1 mole %) and high (7 mole %) concentrations with dipalmitoyl phosphatidylcholine (DPPC) liposomes has been studied in the presence and absence of vitamin D 2 (1 mole %) by using two noninvasive techniques, namely differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. DSC studies reveal that the presence of vitamin D 2 in the pure or Mg 2+ (at both low and high concentrations) containing liposomes diminishes the pretransition. The calorimetric results also reveal that, inclusion of Mg 2+ (more significantly at high concentration) into pure or vitamin D 2 containing DPPC liposomes increases the main phase transition temperature. The investigation of the CH 2 symmetric, the CH 3 asymmetric, the C dbnd O stretching, and the PO2- antisymmetric double bond stretching bands in FTIR spectra with respect to changes occurring in the wavenumber and/or the bandwidth values as a function of temperature reveal that, inclusion of vitamin D 2 or Mg 2+ into pure DPPC liposomes orders and decreases the dynamics of the acyl chains in both gel and liquid-crystalline phases and does not induce hydrogen bond formation in the interfacial region. Furthermore, the dynamics of the head groups of the liposomes decreases in both phases. Our findings reveal that, simultaneous presence of vitamin D 2 and Mg 2+ alters the effect of each other, which is reflected as a decrease in the interactions between these two additives within the model membrane.

  20. Binding of Cu(II) ions to peptides studied by fluorescence spectroscopy and isothermal titration calorimetry.

    PubMed

    Makowska, Joanna; Żamojć, Krzysztof; Wyrzykowski, Dariusz; Uber, Dorota; Wierzbicka, Małgorzata; Wiczk, Wiesław; Chmurzyński, Lech

    2016-01-15

    Steady-state and time-resolved fluorescence quenching measurements supported by Isothermal Titration Calorimetry (ITC) were used to study the interactions of Cu(2+) with four peptides. Two of them were taken from the N-terminal part of the FBP28 protein (formin binding protein) WW domain: Tyr-Lys-Thr-Ala-Asp-Gly-Lys-Thr-Tyr-NH2 (D9) and its mutant Tyr-Lys-Thr-Ala-Asn-Gly-Lys-Thr-Tyr-NH2 (D9_M) as well as two mutated peptides from the B3 domain of the immunoglobulin binding protein G derived from Streptococcus: Asp-Val-Ala-Thr-Tyr-Thr-NH2 (J1) and Glu-Val-Ala-Thr-Tyr-Thr-NH2 (J2). The measurements were carried out at 298.15K in 20mM 2-(N-morpholino)ethanesulfonic acid (MES) buffer solution with a pH of 6. The fluorescence of all peptides was quenched by Cu(2+) ions. The stoichiometry, conditional stability constants and thermodynamic parameters for the interactions of the Cu(2+) ions with D9 and D9_M were determined from the calorimetric data. The values of the conditional stability constants were additionally determined from fluorescence quenching measurements and compared with those obtained from calorimetric studies. There was a good correlation between data obtained from the two techniques. On the other hand, the studies revealed that J1 and J2 do not exhibit an affinity towards metal ions. The obtained results prove that fluorescence quenching experiments may be successfully used in order to determine stability constants of complexes with fluorescent ligands. Finally, based on the obtained results, the coordinating properties of the peptides towards the Cu(2+) ions are discussed.

  1. Binding of Cu(II) ions to peptides studied by fluorescence spectroscopy and isothermal titration calorimetry

    NASA Astrophysics Data System (ADS)

    Makowska, Joanna; Żamojć, Krzysztof; Wyrzykowski, Dariusz; Uber, Dorota; Wierzbicka, Małgorzata; Wiczk, Wiesław; Chmurzyński, Lech

    2016-01-01

    Steady-state and time-resolved fluorescence quenching measurements supported by Isothermal Titration Calorimetry (ITC) were used to study the interactions of Cu2 + with four peptides. Two of them were taken from the N-terminal part of the FBP28 protein (formin binding protein) WW domain: Tyr-Lys-Thr-Ala-Asp-Gly-Lys-Thr-Tyr-NH2 (D9) and its mutant Tyr-Lys-Thr-Ala-Asn-Gly-Lys-Thr-Tyr-NH2 (D9_M) as well as two mutated peptides from the B3 domain of the immunoglobulin binding protein G derived from Streptococcus: Asp-Val-Ala-Thr-Tyr-Thr-NH2 (J1) and Glu-Val-Ala-Thr-Tyr-Thr-NH2 (J2). The measurements were carried out at 298.15 K in 20 mM 2-(N-morpholino)ethanesulfonic acid (MES) buffer solution with a pH of 6. The fluorescence of all peptides was quenched by Cu2 + ions. The stoichiometry, conditional stability constants and thermodynamic parameters for the interactions of the Cu2 + ions with D9 and D9_M were determined from the calorimetric data. The values of the conditional stability constants were additionally determined from fluorescence quenching measurements and compared with those obtained from calorimetric studies. There was a good correlation between data obtained from the two techniques. On the other hand, the studies revealed that J1 and J2 do not exhibit an affinity towards metal ions. The obtained results prove that fluorescence quenching experiments may be successfully used in order to determine stability constants of complexes with fluorescent ligands. Finally, based on the obtained results, the coordinating properties of the peptides towards the Cu2 + ions are discussed.

  2. Electrostatic Interactions in the Binding Pathway of a Transient Protein Complex Studied by NMR and Isothermal Titration Calorimetry*

    PubMed Central

    Meneses, Erick; Mittermaier, Anthony

    2014-01-01

    Much of our knowledge of protein binding pathways is derived from extremely stable complexes that interact very tightly, with lifetimes of hours to days. Much less is known about weaker interactions and transient complexes because these are challenging to characterize experimentally. Nevertheless, these types of interactions are ubiquitous in living systems. The combination of NMR relaxation dispersion Carr–Purcell–Meiboom–Gill (CPMG) experiments and isothermal titration calorimetry allows the quantification of rapid binding kinetics for complexes with submillisecond lifetimes that are difficult to study using conventional techniques. We have used this approach to investigate the binding pathway of the Src homology 3 (SH3) domain from the Fyn tyrosine kinase, which forms complexes with peptide targets whose lifetimes are on the order of about a millisecond. Long range electrostatic interactions have been shown to play a critical role in the binding pathways of tightly binding complexes. The role of electrostatics in the binding pathways of transient complexes is less well understood. Similarly to previously studied tight complexes, we find that SH3 domain association rates are enhanced by long range electrostatics, whereas short range interactions are formed late in the docking process. However, the extent of electrostatic association rate enhancement is several orders of magnitudes less, whereas the electrostatic-free basal association rate is significantly greater. Thus, the SH3 domain is far less reliant on electrostatic enhancement to achieve rapid association kinetics than are previously studied systems. This suggests that there may be overall differences in the role played by electrostatics in the binding pathways of extremely stable versus transient complexes. PMID:25122758

  3. Electrostatic interactions in the binding pathway of a transient protein complex studied by NMR and isothermal titration calorimetry.

    PubMed

    Meneses, Erick; Mittermaier, Anthony

    2014-10-03

    Much of our knowledge of protein binding pathways is derived from extremely stable complexes that interact very tightly, with lifetimes of hours to days. Much less is known about weaker interactions and transient complexes because these are challenging to characterize experimentally. Nevertheless, these types of interactions are ubiquitous in living systems. The combination of NMR relaxation dispersion Carr-Purcell-Meiboom-Gill (CPMG) experiments and isothermal titration calorimetry allows the quantification of rapid binding kinetics for complexes with submillisecond lifetimes that are difficult to study using conventional techniques. We have used this approach to investigate the binding pathway of the Src homology 3 (SH3) domain from the Fyn tyrosine kinase, which forms complexes with peptide targets whose lifetimes are on the order of about a millisecond. Long range electrostatic interactions have been shown to play a critical role in the binding pathways of tightly binding complexes. The role of electrostatics in the binding pathways of transient complexes is less well understood. Similarly to previously studied tight complexes, we find that SH3 domain association rates are enhanced by long range electrostatics, whereas short range interactions are formed late in the docking process. However, the extent of electrostatic association rate enhancement is several orders of magnitudes less, whereas the electrostatic-free basal association rate is significantly greater. Thus, the SH3 domain is far less reliant on electrostatic enhancement to achieve rapid association kinetics than are previously studied systems. This suggests that there may be overall differences in the role played by electrostatics in the binding pathways of extremely stable versus transient complexes.

  4. Differential scanning calorimetry study of glass transition in frozen starch gels.

    PubMed

    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.

  5. Tetraether bolaform amphiphiles as models of archaebacterial membrane lipids: Synthesis, differential scanning calorimetry, and monolayer studies

    SciTech Connect

    Kim, J.M.; Thompson, D.H. )

    1992-02-01

    Four racemic tetraether lipids containing a single 1,[omega]-polymethylene chain ([omega] = 16, 20) bridging two glycerophosphate headgroups (bolaform amphiphiles) have been synthesized. These materials have been characterized at the air-water interface by monolayer balance methods and in buffered solution by differential scanning calorimetry (DSC) and negative stain transmission electron microscopy (TEM). Molecular areas in excess of 100 [angstrom][sup 2]/molecule at 40 mN/m[sup 2] were observed for all bolaamphiphiles studied, suggesting a U-shaped molecular conformation that places both phosphate headgroups in the water subphase. Aqueous dispersions of these lipids have thermal and morphological properties that depend on molecular structure and solution pH. Phase transition temperatures (T[sub c]) of the structural isomers, 2,2[prime]-di-O-decyl-1, 1[prime]-O-eicosamethylene-rac-diglycero-3,3[prime]-diphosphate (PS20) and 1,1[prime]-di-O-decyl-2,2[prime]-O-eicosamethylene-3,3[prime]-diphosphate (SS20), were 49 and 38 [degrees]C, respectively, at pH 2.5. A reduction in the observed T[sub c] of [approximately] 14 [degrees]C occurred when the pH was raised to 8.1. The closely related structural analogue, 1,1[prime]-O-eicosamethylene-2-O-eicosyl-rac-diglycero-3,2[prime], 3[prime]-diphosphate (PA20), has a T[sub c] 85 [degrees]C. No phase transition was observed above 5 [degrees]C for 2,2[prime]-O-dioctyl-1,1 [prime]-O-hexadecylmethylene-rac-diglycero-3, 3[prime]-disphosphoric acid (PS16). Multilamellar structures with hydrocarbon-region spacings of 24-30 [angstrom] and overall lengths approaching 0.3 [mu]m were observed by negative stain electron microscopy. The observed lamellae distance is in good agreement with the membrane thickness expected for a bolaamphiphile in its all-anti conformation. 56 refs., 8 figs., 1 tab.

  6. Relaxation behaviour of D(-)-salicin as studied by Thermally Stimulated Depolarisation Currents (TSDC) and Differential Scanning Calorimetry (DSC).

    PubMed

    Diogo, Hermínio P; Pinto, Susana S; Moura Ramos, Joaquim J

    2008-06-24

    Thermally Stimulated Depolarisation Currents (TSDC) measurements on D(-)-salicin have been carried out in the temperature region from -165 degrees C up to 150 degrees C. The slow molecular mobility was characterised in the crystal and in the glassy state. The value of the steepness index or fragility (T(g)-normalized temperature dependence of the relaxation time) was obtained by Differential Scanning Calorimetry (DSC) from the analysis of the scanning rate dependency of T(g). The existence of an unknown polymorph of salicin is also reported.

  7. Direct calorimetry identifies deficiencies in respirometry for the determination of resting metabolic rate in C57Bl/6 and FVB mice.

    PubMed

    Burnett, Colin M L; Grobe, Justin L

    2013-10-01

    Substantial research efforts have been aimed at identifying novel targets to increase resting metabolic rate (RMR) as an adjunct approach to the treatment of obesity. Respirometry (one form of "indirect calorimetry") is unquestionably the dominant technique used in the obesity research field to assess RMR in vivo, although this method relies upon a lengthy list of assumptions that are likely to be violated in pharmacologically or genetically manipulated animals. A "total" calorimeter, including a gradient layer direct calorimeter coupled to a conventional respirometer, was used to test the accuracy of respirometric-based estimations of RMR in laboratory mice (Mus musculus Linnaeus) of the C57Bl/6 and FVB background strains. Using this combined calorimeter, we determined that respirometry underestimates RMR of untreated 9- to 12-wk-old male mice by ∼10-12%. Quantitative and qualitative differences resulted between methods for untreated C57Bl/6 and FVB mice, C57Bl/6 mice treated with ketamine-xylazine anesthesia, and FVB mice with genetic deletion of the angiotensin II type 2 receptor. We conclude that respirometric methods underestimate RMR in mice in a magnitude that is similar to or greater than the desired RMR effects of novel therapeutics. Sole reliance upon respirometry to assess RMR in mice may lead to false quantitative and qualitative conclusions regarding the effects of novel interventions. Increased use of direct calorimetry for the assessment of RMR and confirmation of respirometry results and the reexamination of previously discarded potential obesity therapeutics are warranted.

  8. Theoretical studies of hadronic calorimetry for high luminosity, high energy colliders

    SciTech Connect

    Brau, J.E.; Gabriel, T.A.

    1989-01-01

    Experiments at the high luminosity, high energy colliders of the future are going to demand optimization of the state of the art of calorimetry design and construction. During the past few years, the understanding of the basic phenomenology of hadron calorimeters has advanced through paralleled theoretical and experimental investigations. The important underlying processes are reviewed to set the framework for the presentation of recent calculations of the expected performance of silicon detector based hadron calorimeters. Such devices employing uranium are expected to achieve the compensation condition (that is, e/h approx. 1.0) based on the understanding that has been derived from the uranium-liquid argon and uranium-plastic scintillator systems. In fact, even lead-silicon calorimeters are found to achieve the attractive value for the e/h ratio of 1.16 at 10 GeV. 62 refs., 22 figs., 3 tabs.

  9. Phase Polymorphism of [Co(DMSO)6](BF4)2 Studied by Differential Scanning Calorimetry

    NASA Astrophysics Data System (ADS)

    Migdał-Mikuli, Anna; Skoczylas, Łukasz; Szostak, Elżbieta

    2006-04-01

    Five solid phases of [Co(DMSO)6](BF4)2 have been detected by differential scanning calorimetry (DSC). Phase transitions were detected between the following solid phases: stable KIb↔ stable KIa at T̅C4 = (328±2) K, metastable KIII ↔ undercooled phase K0 at T̅C3 = (383±4) K, metastable KII ↔ undercooled K0 at T̅C2 = (399±2) K and stable KIa ↔ stable K0 at T̅C1 = (404±1) K. The title compound melts at Tm = 440 K. From the entropy changes at the melting point and at phase transitions it can be concluded that the phases K0 and undercooled K0 are orientationally dynamically disordered crystals. The stable phases KIa, KIb are ordered solid phases. The metastable phases KII and KIII are probably solid phases with a high degree of orientational dynamical disorder

  10. Integration and global analysis of isothermal titration calorimetry data for studying macromolecular interactions.

    PubMed

    Brautigam, Chad A; Zhao, Huaying; Vargas, Carolyn; Keller, Sandro; Schuck, Peter

    2016-05-01

    Isothermal titration calorimetry (ITC) is a powerful and widely used method to measure the energetics of macromolecular interactions by recording a thermogram of differential heating power during a titration. However, traditional ITC analysis is limited by stochastic thermogram noise and by the limited information content of a single titration experiment. Here we present a protocol for bias-free thermogram integration based on automated shape analysis of the injection peaks, followed by combination of isotherms from different calorimetric titration experiments into a global analysis, statistical analysis of binding parameters and graphical presentation of the results. This is performed using the integrated public-domain software packages NITPIC, SEDPHAT and GUSSI. The recently developed low-noise thermogram integration approach and global analysis allow for more precise parameter estimates and more reliable quantification of multisite and multicomponent cooperative and competitive interactions. Titration experiments typically take 1-2.5 h each, and global analysis usually takes 10-20 min.

  11. Differential scanning calorimetry study of deoxyadenosine and its water of hydration

    NASA Astrophysics Data System (ADS)

    Cooper, R. L.; Lee, S. A.

    2002-03-01

    Elucidating the interactions between the hydration of water and DNA is important for understanding the function of DNA. Differential scanning calorimetry (DSC) has been used to measure the activation energy and enthalpy associated with the removal of this water from the nucleoside deoxyadenosine (dA). Pristine samples were found to contain water of crystallization since the samples were prepared from solution by evaporation. Following an initial dehydration, it is necessary to expose the dA to a relative humidity above 84 percent in order to rehydrate the sample. For such rehydrated samples, the DSC measurements yield 1.60 ± 0.20 eV/H_20 and 175 ± 80 J/g for the activation energy and enthalpy, respectively. These energies remain the same for all higher relative humidities. We provide a simple model of this rehydration process.

  12. Irreversible Thermal Denaturation of β-Hemocyanin of Helix pomatia and its Substructures Studied by Differential Scanning Calorimetry

    NASA Astrophysics Data System (ADS)

    Idakieva, Krassimira; Gielens, Constant; Siddiqui, Nurul I.; Doumanova, Lyubka; Vasseva, Boyka; Kostov, Georgi; Shnyrov, Valery L.

    2007-09-01

    The thermal denaturation of β -hemocyanin from the gastropod Helix pomatia (β -HpH) at neutral pH was studied by means of differential scanning calorimetry (DSC). The denaturation was completely irreversible as judged by the absence of any endotherm on rescanning previously scanned samples. Two transitions, with apparent transition temperatures (Tm) of ca. 84 °C (main transition) and ca. 88 °C (minor transition), were detected by DSC in 20 mM MOPS buffer, containing 0.1 M NaCl, 5mM CaCl2 and 5 mM MgCl2 at pH 7.2 (buffer A), using a heating rate of 1.0 Kmin-1. Both Tm values were dependent on the scanning rate, suggesting that the thermal denaturation of β -HpH is a kinetically controlled process. The Tm and specific enthalpy values (ΔHcal) for the thermal denaturation of β -HpH were found to be independent of the protein concentration, indicating that the dissociation of the protein into monomers does not take place before the rate-determining step of the process of thermal unfolding started. A successive annealing procedure was applied to obtain the experimental deconvolution of the irreversible thermal transitions. These transitions are tentatively attributed to the denaturation of, respectively, the wall (main transition) and the collar of the β -HpH molecule. The activation energies (EA) of both transitions were found to be similar (about 500 kJ mol-1). In 130 mM glycine/NaOH buffer, pH 9.6 (buffer B), with β -HpH dissociated into subunits, the calorimetric profile had a more complex character. This could be ascribed to a different stability of the functional units (FUs) constituting the β -HpH subunit. FU d, which in the cylindrical didecameric β -HpH molecule is located in the wall, was markedly less stable than FU g, which belongs to the collar. The thermal denaturation of FUs d and g was described by the two-state irreversible model. On the basis of this model, the parameters of the Arrhenius equation were calculated.

  13. Study of the thermal behavior of choline ibuprofenate using differential scanning calorimetry and hot-stage microscopy

    NASA Astrophysics Data System (ADS)

    Diogo, Hermínio P.; Moura Ramos, Joaquim J.

    2014-12-01

    The phase transformations in choline ibuprofenate, [chol][ibu], have been studied by differential scanning calorimetry (DSC) and hot-stage microscopy (HSM). Two crystalline forms, α and β, were identified that are very different in their thermal behavior, and thus probably very different in their crystal structures. The melting temperatures of the two crystal polymorphs differ as much as 50°. The higher temperature polymorph, α, presents a sharp and fast crystallization process, while the melting transformation displays a very slow dynamics. The β polymorph forms on cooling through a broad crystal-to-crystal transformation, and displays a melting process that is sharp compared with that of α polymorph.

  14. Binding of Ru(terpyridine)(pyridine)dipyridophenazine to DNA studied with polarized spectroscopy and calorimetry.

    PubMed

    Mårtensson, Anna K F; Lincoln, Per

    2015-02-28

    Linear and circular dichroism (LD and CD) spectroscopy as well as isothermal titration calorimetry (ITC) have been used to investigate the interaction of Ru(tpy)(py)dppz(2+) (tpy = 2,2':6',2''-terpyridyl; py = pyridine; dppz = dipyrido[3,2-a:2'3'-c]phenazine) with DNA, providing detailed information about the DNA binding thermodynamics and binding geometry of the metal complex. Flow LD, CD and isotropic absorption indicate that Ru(tpy)(py)dppz(2+) bind to DNA from the minor groove with the dppz ligand intercalated between base pairs, very similar to its chiral structural isomers Δ- and Λ-Ru(bpy)2dppz(2+) (bpy = 2,2'-bipyridine). A simple cooperative binding model with one binding geometry provide an excellent fit for calorimetric and absorption titration data. The values of the neighbor interaction thermodynamic parameters for Ru(tpy)(py)dppz(2+) suggest that complexes bound contiguously prefer to have their tpy ligands oriented towards the same strand.

  15. Isothermal titration calorimetry studies of neutral salt effects on the thermodynamics of micelle formation.

    PubMed

    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.

  16. Thermodynamics of cationic lipid-DNA complex formation as studied by isothermal titration calorimetry.

    PubMed

    Pozharski, Edwin; MacDonald, Robert C

    2002-07-01

    The detailed analysis of the cationic lipid-DNA complex formation by means of isothermal titration calorimetry is presented. Most experiments were done using 1,2-dioleyl-sn-glycero-3-ethylphosphocholine (EDOPC), but basic titrations were also done using DOTAP, DOTAP:DOPC, and DOTAP:DOPE mixtures. Complex formation was endothermic with less than 1 kcal absorbed per mole of lipid or DNA charge. This enthalpy change was attributed to DNA-DNA mutual repulsion within the lamellar complex. The exception was DOTAP:DOPE-containing lipoplex for which the enthalpy of formation was exothermic, presumably because of DOPE amine group protonation. Experimental conditions, namely, direction and titration increment as well as concentration of titrant, which dictate the structure of resulting lipoplex (whether lamellar complex or DNA-coated vesicle), were found to affect the apparent thermodynamics of complex formation. The structure, in turn, influences the biological properties of the lipoplex. If the titration of lipid into DNA was carried out in large increments, the DeltaH was larger than when the injection increments were smaller, a finding that is consistent with increased vesicle disruption under large increments and which is expected theoretically. Cationic lipid-DNA binding was weak in high ionic strength solutions, however, the effective binding constant is within micromolar range because of macromolecular nature of the interaction.

  17. Porosity and Surface Properites of SBA-15 with Grafted PNIPAAM: A Water Sorption Calorimetry Study

    PubMed Central

    2011-01-01

    Mesoporous silica SBA-15 was modified in a three-step process to obtain a material with poly-N-isopropylacrylamide (PNIPAAM) grafted onto the inner pore surface. Water sorption calorimetry was implemented to characterize the materials obtained after each step regarding the porosity and surface properties. The modification process was carried out by (i) increasing the number of surface silanol groups, (ii) grafting 1-(trichlorosilyl)-2-(m-/p-(chloromethylphenyl) ethane, acting as an anchor for (iii) the polymerization of N-isopropylacrylamide. Water sorption isotherms and the enthalpy of hydration are presented. Pore size distributions were calculated on the basis of the water sorption isotherms by applying the BJH model. Complementary measurements with nitrogen sorption and small-angle X-ray diffraction are presented. The increase in the number of surface silanol groups occurs mainly in the intrawall pores, the anchor is mainly located in the intrawall pores, and the intrawall pore volume is absent after the surface grafting of PNIPAAM. Hence, PNIPAAM seals off the intrawall pores. Water sorption isotherms directly detect the presence of intrawall porosity. Pore size distributions can be calculated from the isotherms. Furthermore, the technique provides information regarding the hydration capability (i.e., wettability of different chemical surfaces) and thermodynamic information. PMID:21928772

  18. Thermodynamics of cationic lipid-DNA complex formation as studied by isothermal titration calorimetry.

    PubMed Central

    Pozharski, Edwin; MacDonald, Robert C

    2002-01-01

    The detailed analysis of the cationic lipid-DNA complex formation by means of isothermal titration calorimetry is presented. Most experiments were done using 1,2-dioleyl-sn-glycero-3-ethylphosphocholine (EDOPC), but basic titrations were also done using DOTAP, DOTAP:DOPC, and DOTAP:DOPE mixtures. Complex formation was endothermic with less than 1 kcal absorbed per mole of lipid or DNA charge. This enthalpy change was attributed to DNA-DNA mutual repulsion within the lamellar complex. The exception was DOTAP:DOPE-containing lipoplex for which the enthalpy of formation was exothermic, presumably because of DOPE amine group protonation. Experimental conditions, namely, direction and titration increment as well as concentration of titrant, which dictate the structure of resulting lipoplex (whether lamellar complex or DNA-coated vesicle), were found to affect the apparent thermodynamics of complex formation. The structure, in turn, influences the biological properties of the lipoplex. If the titration of lipid into DNA was carried out in large increments, the DeltaH was larger than when the injection increments were smaller, a finding that is consistent with increased vesicle disruption under large increments and which is expected theoretically. Cationic lipid-DNA binding was weak in high ionic strength solutions, however, the effective binding constant is within micromolar range because of macromolecular nature of the interaction. PMID:12080142

  19. A Laboratory to Demonstrate the Effect of Thermal History on Semicrystalline Polymers Using Rapid Scanning Rate Differential Scanning Calorimetry

    ERIC Educational Resources Information Center

    Badrinarayanan, Prashanth; Kessler, Michael R.

    2010-01-01

    A detailed understanding of the effect of thermal history on the thermal properties of semicrystalline polymers is essential for materials scientists and engineers. In this article, we describe a materials science laboratory to demonstrate the effect of parameters such as heating rate and isothermal annealing conditions on the thermal behavior of…

  20. Application of calorimetry to microbial biodegradation studies of agrochemicals in oxisols.

    PubMed

    Critter, S A; Airoldi, C

    2001-01-01

    Calorimetry was used to monitor the inhibitory effect caused by the bipyridynium diquaternary salts paraquat, diquat, and phosphamidon on microbial activity in a Red Latosol soil (Oxisol). The thermal effect was recorded on samples composed of 1.50 g of soil, 6.0 mg of glucose, 6.0 mg of ammonium sulfate, and different masses of an inhibitor ranging from zero to 8.00 mg, under a controlled moisture content of 35%. Thermal effects of each pollutant on the degradation curves of glucose in the soil were compared. Increasing amounts of the inhibitor caused a decrease in the thermal effect from -2234 to -1987 kJ mol(-1) for paraquat, -1670 to -1306 kJ mol(-1) for diquat, and -2239 to -589 kJ mol(-1) for phosphamidon. The last xenobiotic agent caused a significant inhibitory effect on the microbial activity of the soil. The results of relative efficiency, eta = deltaH/deltaH', referring to the enthalpic value with (deltaH) and without (deltaH') agrochemical in the soil, exhibited a significant correlation. From this correlation obtained for the ranges 2.00 to 8.00, 1.30 to 8.00, and 1.20 to 5.80 mg of the agrochemicals paraquat, diquat, and phosphamidon, respectively, the following eta values were calculated: 0.993 to 0.894, 0.668 to 0.522, and 0.896 to 0.236, respectively, during the degradation of glucose in the soil. The largest relative efficiency for paraquat implies that this agrochemical can be metabolized by microbial activity.

  1. Slow molecular mobility in the crystalline and amorphous solid states of pentitols: a study by thermally stimulated depolarisation currents and by differential scanning calorimetry.

    PubMed

    Diogo, Hermínio P; Pinto, Susana S; Moura Ramos, Joaquim J

    2007-05-21

    The molecular mobility of the pentitol isomers (xylitol, adonitol, D-arabitol and L-arabitol) was studied by thermally stimulated depolarisation currents (TSDC) in the crystalline and in the amorphous solid states. Differential scanning calorimetry (DSC) was used to characterise the phase transformations, to detect polymorphism and to analyse the dynamics of the structural relaxation in the glassy state (from the heating rate dependence of the onset temperature of the glass transition signal). The mobility in crystalline xylitol and adonitol displays features that are different compared with crystalline arabitols. No difference of the dynamic behaviour seems to emerge from our results on the primary and secondary relaxations in the amorphous isomeric pentitols. The values of the steepness index or fragility obtained in this work by TSDC and DSC are compared with the values reported in the literature obtained from other experimental techniques, and with values predicted by empirical formulae.

  2. Overabundance of carbon monoxide in calorimetry tests

    SciTech Connect

    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.

  3. Confined water in controlled pore glass CPG-10-120 studied by positron annihilation lifetime spectroscopy and differential scanning calorimetry

    NASA Astrophysics Data System (ADS)

    Šauša, O.; Mat'ko, I.; Illeková, E.; Macová, E.; Berek, D.

    2015-06-01

    The solidification and melting of water confined in the controlled pore glass (CPG) with average pore size 12.6 nm has been studied by differential scanning calorimetry (DSC) and positron annihilation lifetime spectroscopy (PALS). The fully-filled sample of CPG by water as well as the samples of CPG with different content of water were used. The measurements show the presence of amorphous and crystalline phases of water in this type and size of pores, freezing point depression of a confined liquid and presence of certain transitions at lower temperatures, which could be detected only for cooling regime. The localization of confined water in the partially filled pores of CPG at room temperature was studied.

  4. Interaction of phenazinium dyes with double-stranded poly(A): spectroscopy and isothermal titration calorimetry studies.

    PubMed

    Khan, Asma Yasmeen; Saha, Baishakhi; Kumar, Gopinatha Suresh

    2014-10-15

    A comprehensive study on the binding of phenazinium dyes viz. janus green B, indoine blue, safranine O and phenosafranine with double stranded poly(A) using various spectroscopic and calorimetric techniques is presented. A higher binding of janus green B and indoine blue over safranine O and phenosafranine to poly(A) was observed from all experiments. Intercalative mode of binding of the dyes was inferred from fluorescence polarization anisotropy, iodide quenching and viscosity experiments. Circular dichroism study revealed significant perturbation of the secondary structure of poly(A) on binding of these dyes. Results from isothermal titration calorimetry experiments suggested that the binding was predominantly entropy driven with a minor contribution of enthalpy to the standard molar Gibbs energy. The results presented here may open new opportunities in the application of these dyes as RNA targeted therapeutic agents.

  5. Binding between bixin and whey protein at pH 7.4 studied by spectroscopy and isothermal titration calorimetry.

    PubMed

    Zhang, Yue; Zhong, Qixin

    2012-02-22

    Bixin is the major coloring component of annatto used in manufacturing colored cheeses, but its presence in liquid whey causes undesirable quality of the recovered whey protein ingredients. The objective of this work was to study molecular binding between bixin and three major whey proteins (β-lactoglobulin, α-lactalbumin, and bovine serum albumin) at pH 7.4 using UV-vis absorption spectroscopy, fluorescence spectroscopy, isothermal titration calorimetry, and circular dichroism. These complementary techniques illustrated that the binding is a spontaneous complexation process mainly driven by hydrophobic interactions. The complexation is favored at a lower temperature and a higher ionic strength. At a lower temperature, the binding is entropy-driven, while it changes to an enthalpy-driven process at higher temperatures. The binding also increases the percentage of unordered secondary structures of proteins. Findings from this work can be used to develop whey protein recovery processes for minimizing residual annatto content in whey protein ingredients.

  6. Lipid membrane domain formation and alamethicin aggregation studied by calorimetry, sound velocity measurements, and atomic force microscopy.

    PubMed

    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.

  7. Calorimetry and Langmuir-Blodgett studies on the interaction of a lipophilic prodrug of LHRH with biomembrane models.

    PubMed

    Sarpietro, Maria G; Accolla, Maria L; Santoro, Nancy; Mansfeld, Friederike M; Pignatello, Rosario; Toth, Istvan; Castelli, Francesco

    2014-05-01

    The interaction between an amphiphilic luteinizing hormone-releasing hormone (LHRH) prodrug that incorporated a lipoamino acid moiety (C12-LAA) with biological membrane models that consisted of multilamellar liposomes (MLVs) and phospholipid monolayers, was studied using Differential Scanning Calorimetry (DSC) and Langmuir-Blodgett film techniques. The effect of the prodrug C12[Q1]LHRH on the lipid layers was compared with the results obtained with the pure precursors, LHRH and C12-LAA. Conjugation of LHRH with a LAA promoiety showed to improve the peptide interaction with biomembrane models. Basing on the calorimetric findings, the LAA moiety aided the transfer of the prodrug from an aqueous solution to the biomembrane model.

  8. Direct Animal Calorimetry, the Underused Gold Standard for Quantifying the Fire of Life*

    PubMed Central

    Kaiyala, Karl J.; Ramsay, Douglas S.

    2012-01-01

    Direct animal calorimetry, the gold standard method for quantifying animal heat production (HP), has been largely supplanted by respirometric indirect calorimetry owing to the relative ease and ready commercial availability of the latter technique. Direct calorimetry, however, can accurately quantify HP and thus metabolic rate (MR) in both metabolically normal and abnormal states, whereas respirometric indirect calorimetry relies on important assumptions that apparently have never been tested in animals with genetic or pharmacologically-induced alterations that dysregulate metabolic fuel partitioning and storage so as to promote obesity and/or diabetes. Contemporary obesity and diabetes research relies heavily on metabolically abnormal animals. Recent data implicating individual and group variation in the gut microbiome in obesity and diabetes raise important questions about transforming aerobic gas exchange into HP because 99% of gut bacteria are anaerobic and they outnumber eukaryotic cells in the body by ~10-fold. Recent credible work in non-standard laboratory animals documents substantial errors in respirometry-based estimates of HP. Accordingly, it seems obvious that new research employing simultaneous direct and indirect calorimetry (total calorimetry) will be essential to validate respirometric MR phenotyping in existing and future pharmacological and genetic models of obesity and diabetes. We also detail the use of total calorimetry with simultaneous core temperature assessment as a model for studying homeostatic control in a variety of experimental situations, including acute and chronic drug administration. Finally, we offer some tips on performing direct calorimetry, both singly and in combination with indirect calorimetry and core temperature assessment. PMID:20427023

  9. Direct animal calorimetry, the underused gold standard for quantifying the fire of life.

    PubMed

    Kaiyala, Karl J; Ramsay, Douglas S

    2011-03-01

    Direct animal calorimetry, the gold standard method for quantifying animal heat production (HP), has been largely supplanted by respirometric indirect calorimetry owing to the relative ease and ready commercial availability of the latter technique. Direct calorimetry, however, can accurately quantify HP and thus metabolic rate (MR) in both metabolically normal and abnormal states, whereas respirometric indirect calorimetry relies on important assumptions that apparently have never been tested in animals with genetic or pharmacologically-induced alterations that dysregulate metabolic fuel partitioning and storage so as to promote obesity and/or diabetes. Contemporary obesity and diabetes research relies heavily on metabolically abnormal animals. Recent data implicating individual and group variation in the gut microbiome in obesity and diabetes raise important questions about transforming aerobic gas exchange into HP because 99% of gut bacteria are anaerobic and they outnumber eukaryotic cells in the body by ∼10-fold. Recent credible work in non-standard laboratory animals documents substantial errors in respirometry-based estimates of HP. Accordingly, it seems obvious that new research employing simultaneous direct and indirect calorimetry (total calorimetry) will be essential to validate respirometric MR phenotyping in existing and future pharmacological and genetic models of obesity and diabetes. We also detail the use of total calorimetry with simultaneous core temperature assessment as a model for studying homeostatic control in a variety of experimental situations, including acute and chronic drug administration. Finally, we offer some tips on performing direct calorimetry, both singly and in combination with indirect calorimetry and core temperature assessment.

  10. Eu(3+)-mediated polymerization of benzenetetracarboxylic acid studied by spectroscopy, temperature-dependent calorimetry, and density functional theory.

    PubMed

    Barkleit, Astrid; Tsushima, Satoru; Savchuk, Olesya; Philipp, Jenny; Heim, Karsten; Acker, Margret; Taut, Steffen; Fahmy, Karim

    2011-06-20

    Thermodynamic parameters for the complexation of Eu(3+) with pyromellitic acid (1,2,4,5-benzenetetracarboxylic acid, BTC) as a model system for polymerizable metal-complexing humic acids were determined using temperature-dependent time-resolved laser-induced fluorescence spectroscopy (TRLFS) and isothermal titration calorimetry (ITC). At low metal and ligand concentrations (<50 μM Eu(3+), <1 mM BTC), a 1:1 monomeric Eu-BTC complex was identified in the range of 25-60 °C. At elevated concentrations (>500 μM Eu(3+) and BTC) a temperature-dependent polymerization was observed, where BTC monomers are linked via coordinating shared Eu(3+) ions. The two methods lead to comparable thermodynamic data (ΔH = 18.5 ± 1.5/16.5 ± 0.1 kJ mol(-1); ΔS = 152 ± 5/130 ± 5 J mol(-1) K(-1); TRLFS/ITC) in the absence of polymerization. With the onset of polymerization, TRLFS reveals the water coordination number of the lanthanide, whereas calorimetry is superior in determining the thermodynamic data in this regime. Evaluating the heat uptake kinetics, the monomer and polymer formation steps could be separated by "time-resolved" ITC, revealing almost identical binding enthalpies for the sequential reactions. Structural features of the complexes were studied by Fourier-transform infrared (FTIR) spectroscopy in combination with density functional theory (DFT) calculations showing predominantly chelating coordination with two carboxylate groups in the monomeric complex and monodentate binding of a single carboxylate group in the polymeric complex of the polycarboxylate with Eu(3+). The data show that pyromellitic acid is a suitable model for the study of metal-mediated polymerization as a crucial factor in determining the effect of humic acids on the mobility of heavy metals in the environment.

  11. A potential role for isothermal calorimetry in studies of the effects of thermodynamic non-ideality in enzyme-catalyzed reactions.

    PubMed

    Lonhienne, Thierry G A; Winzor, Donald J

    2004-01-01

    Attention is drawn to the feasibility of using isothermal calorimetry for the characterization of enzyme reactions under conditions bearing greater relevance to the crowded biological environment, where kinetic parameters are likely to differ significantly from those obtained by classical enzyme kinetic studies in dilute solution. An outline of the application of isothermal calorimetry to the determination of enzyme kinetic parameters is followed by considerations of the nature and consequences of crowding effects in enzyme catalysis. Some of those effects of thermodynamic non-ideality are then illustrated by means of experimental results from calorimetric studies of the effect of molecular crowding on the kinetics of catalysis by rabbit muscle pyruvate kinase. This review concludes with a discussion of the potential of isothermal calorimetry for the experimental determination of kinetic parameters for enzymes either in biological environments or at least in media that should provide reasonable approximations of the crowded conditions encountered in vivo.

  12. Contactless Calorimetry for Levitated Samples

    NASA Technical Reports Server (NTRS)

    Lee, M. C.; Dokko, W.

    1986-01-01

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

  13. Calorimetry of Nucleic Acids.

    PubMed

    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.

  14. Interaction of a dietary fiber (pectin) with gastrointestinal components (bile salts, calcium, and lipase): a calorimetry, electrophoresis, and turbidity study.

    PubMed

    Espinal-Ruiz, Mauricio; Parada-Alfonso, Fabián; Restrepo-Sánchez, Luz-Patricia; Narváez-Cuenca, Carlos-Eduardo; McClements, David Julian

    2014-12-31

    An in vitro gastrointestinal model consisting of oral, gastric, and intestinal phases was used to elucidate the impact of pectin on the digestion of emulsified lipids. Pectin reduced the extent of lipid digestion, which was attributed to its binding interactions with specific gastrointestinal components. The interaction of pectin with bile salts, lipase, CaCl2, and NaCl was therefore investigated by turbidity, microstructure, electrophoresis, and isothermal titration calorimetry (ITC) at pH 7.0 and 37 °C. ITC showed that the interaction of pectin was endothermic with bile salts, but exothermic with CaCl2, NaCl, and lipase. Electrophoresis, microstructure, and turbidity measurements showed that anionic pectin formed electrostatic complexes with calcium ions, which may have decreased lipid digestion due to increased lipid flocculation or microgel formation because this would reduce the surface area of lipid exposed to the lipase. This research provides valuable insights into the physicochemical and molecular mechanisms of the interaction of pectin with gastrointestinal components that may affect the rate and extent of lipid digestion.

  15. Interaction of Bile Salts with Model Membranes Mimicking the Gastrointestinal Epithelium: A Study by Isothermal Titration Calorimetry.

    PubMed

    Coreta-Gomes, Filipe M; Martins, Patrícia A T; Velazquez-Campoy, Adrián; Vaz, Winchil L C; Geraldes, Carlos F G; Moreno, Maria João

    2015-08-25

    Bile salts (BS) are biosurfactants synthesized in the liver and secreted into the intestinal lumen where they solubilize cholesterol and other hydrophobic compounds facilitating their gastrointestinal absorption. Partition of BS toward biomembranes is an important step in both processes. Depending on the loading of the secreted BS micelles with endogeneous cholesterol and on the amount of cholesterol from diet, this may lead to the excretion or absorption of cholesterol, from cholesterol-saturated membranes in the liver or to gastrointestinal membranes, respectively. The partition of BS toward the gastrointestinal membranes may also affect the barrier properties of those membranes affecting the permeability for hydrophobic and amphiphilic compounds. Two important parameters in the interaction of the distinct BS with biomembranes are their partition coefficient and the rate of diffusion through the membrane. Altogether, they allow the calculation of BS local concentrations in the membrane as well as their asymmetry in both membrane leaflets. The local concentration and, most importantly, its asymmetric distribution in the bilayer are a measure of induced membrane perturbation, which is expected to significantly affect its properties as a cholesterol donor and hydrophobic barrier. In this work we have characterized the partition of several BS, nonconjugated and conjugated with glycine, to large unilamellar vesicles (LUVs) in the liquid-disordered phase and with liquid-ordered/liquid-disordered phase coexistence, using isothermal titration calorimetry (ITC). The partition into the liquid-disordered bilayer was characterized by large partition coefficients and favored by enthalpy, while association with the more ordered membrane was weak and driven only by the hydrophobic effect. The trihydroxy BS partitions less efficiently toward the membranes but shows faster translocation rates, in agreement with a membrane protective effect of those BS. The rate of translocation

  16. 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.

  17. Basal Metabolic Rate of Adolescent Modern Pentathlon Athletes: Agreement between Indirect Calorimetry and Predictive Equations and the Correlation with Body Parameters

    PubMed Central

    Loureiro, Luiz Lannes; Fonseca, Sidnei; Castro, Natalia Gomes Casanova de Oliveira e; dos Passos, Renata Baratta; Porto, Cristiana Pedrosa Melo; Pierucci, Anna Paola Trindade Rocha

    2015-01-01

    Purpose The accurate estimative of energy needs is crucial for an optimal physical performance among athletes and the basal metabolic rate (BMR) equations often are not well adjusted for adolescent athletes requiring the use of specific methods, such as the golden standard indirect calorimetry (IC). Therefore, we had the aim to analyse the agreement between the BMR of adolescents pentathletes measured by IC and estimated by commonly used predictive equations. Methods Twenty-eight athletes (17 males and 11 females) were evaluated for BMR, using IC and the predictive equations Harris and Benedict (HB), Cunningham (CUN), Henry and Rees (HR) and FAO/WHO/UNU (FAO). Body composition was obtained using DXA and sexual maturity data were retrieved through validated questionnaires. The correlations among anthropometric variables an IC were analysed by T-student test and ICC, while the agreement between IC and the predictive equations was analysed according to Bland and Altman and by survival-agreement plotting. Results The whole sample average BMR measured by IC was significantly different from the estimated by FAO (p<0.05). Adjusting data by gender FAO and HR equations were statistically different from IC (p <0.05) among males, while female differed only for the HR equation (p <0.05). Conclusion The FAO equation underestimated athletes’ BMR when compared with IC (T Test). When compared to the golden standard IC, using Bland and Altman, ICC and Survival-Agreement, the equations underestimated the energy needs of adolescent pentathlon athletes up to 300kcal/day. Therefore, they should be used with caution when estimating individual energy requirements in such populations. PMID:26569101

  18. Isothermal titration calorimetry study of the interaction of sweeteners with fullerenols as an artificial sweet taste receptor model.

    PubMed

    Chen, Zhong-Xiu; Guo, Gang-Min; Deng, Shao-Ping

    2009-04-08

    A fullerenol-based synthetic sweetness receptor model, consisting of polyhydroxy groups for potential hydrogen bond donor along with a spherical hydrophobic center, was proposed according to the widely accepted sweetness hypothesis. An isothermal titration calorimetry (ITC) technique was used to study mimetic interaction of this sweet receptor model with a series of sweeteners having increasing sweetness intensity. The results showed that ITC is an effective method to provide thorough and precise characterization of the energies of molecular complex formation. Binding of all of the studied sweeteners with fullerenols was found through two sets of site models. More heat was released from sweeter synthetic compounds binding with fullerenols than from less sweet carbohydrates. The results imply that hydrogen bond formation is necessary for the sweeteners to bind to the fullerenol receptor in the first stage, whereas hydrophobic effect and conformation changes that lead to favorable entropy changes occur in most cases. The preliminary results of this study help to cover the lack of information about the thermodynamic basis of understanding of the initiation of the sweet sensation. It also adds complementary physicochemical measurements available for comparison with the sweetness hypothesis. On the other hand, a correlation between the thermodynamic parameters and sweetness intensity has been made as well, which exhibits potential as a useful tool in sensory analysis.

  19. New approach to study starch gelatinization applying a combination of hot-stage light microscopy and differential scanning calorimetry.

    PubMed

    Li, Qian; Xie, Qin; Yu, Shujuan; Gao, Qunyu

    2013-02-13

    To overcome the difficulty of the original polarizing microscope-based method in monitoring the gelatinization of starch, a new method for dynamically monitoring the gelatinization process, integral optical density (IOD), which was based on the digital image analysis technique, was proposed. Hot-stage light microscopy and differential scanning calorimetry (DSC) techniques were coupled to study the dynamic changes of three types of starches: type A (corn starch), type B (potato starch), and type C (pea starch), during the gelatinization process in an excess water system. A model of response difference change of crystallite could represent the responding intensity of crystallization changes in the process of starch gelatinization. Results demonstrated that three crystalline types of starch underwent a process of swelling, accompanied with gradual disappearing of the crystallite. This difference was mainly associated with the diversity and composition of the starch structure. The IOD method was of advantage compared to the previous traditional methods that are based on a polarization microscope, such as counting the particle number and calculating polarization area methods, because it was the product of two parameters: optical density and area, which would be a response of both light intensity and area of birefringence light. The single peak in DSC corresponded to the combination of crystalline helix-helix dissociation and the reduction of the molecule helix-coil transition, while the gelatinization degree measured by the IOD method mainly corresponded to the helix-helix dissociation. The gelatinization mechanism could be revealed clearer in this study.

  20. Designing isothermal titration calorimetry experiments for the study of 1:1 binding: problems with the "standard protocol".

    PubMed

    Tellinghuisen, Joel

    2012-05-15

    Literature recommendations for designing isothermal titration calorimetry (ITC) experiments to study 1:1 binding, M+X -->/<-- MX, are not consistent and have persisted through time with little quantitative justification. In particular, the "standard protocol" employed by most workers involves 20 to 30 injections of titrant to a final titrant/titrand mole ratio (R(m)) of ~ 2-a scheme that can be far from optimal and can needlessly limit applicability of the ITC technique. These deficiencies are discussed here along with other misconceptions. Whether a specific binding process can be studied by ITC is determined less by c (the product of binding constant K and titrand concentration [M](0)) than by the total detectable heat q(tot) and the extent to which M can be converted to MX. As guidelines, with 90% conversion to MX, K can be estimated within 5% over the range 10 to 10(8)M(-1) when q(tot)/σ(q)≈700, where σ(q) is the standard deviation for estimation of q. This ratio drops to ~150 when the stoichiometry parameter n is treated as known. A computer application for modeling 1:1 binding yields realistic estimates of parameter standard errors for use in protocol design and feasibility assessment.

  1. Dijet mass resolution and compensating calorimetry

    SciTech Connect

    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.

  2. Interaction of insulin, cholesterol-derivatized mannan, and carboxymethyl chitin with liposomes: A differential scanning calorimetry study

    PubMed Central

    Tabbakhian, M.; Rogers, J.A.

    2012-01-01

    The interaction of drugs and polymers used to incorporate in or surface modify/coat the liposomes can affect the phase transition, fluidity and other physical properties as well as in vivo fate of vesicles. In this study, differential scanning calorimetry (DSC) was used to investigate changes in the temperature and the enthalpy of phase transition of liposomes of various electrical charges following interaction with carboxymethyl chitin (CM-chitin) as a hydrophilic polymer, cholesterol-derivatized mannan (CHM) as a hydrophilic polymer bearing a hydrophobic moiety, and insulin as a model peptide. The results indicated that insulin incorporation or polymers caused no significant change in the phase transition temperature (Tm) of liposomes. However, reduction in the enthalpy of the transition (ΔH°) following coating with CHM supports an anchoring mechanism to the bilayer by the polymer, whereas no change or little increase in the ΔH° after coating with carboxymethyl chitin suggests no significant interaction or electrostatic weak interactions of polymer with liposomes. The DSC data of liposome-polymer interaction may be suggestive of changes in membrane fluidity, drug release, and possibly the behavior of liposomes in biological milieu. PMID:23181079

  3. Raman scattering boson peak and differential scanning calorimetry studies of the glass transition in tellurium-zinc oxide glasses.

    PubMed

    Stavrou, E; Tsiantos, C; Tsopouridou, R D; Kripotou, S; Kontos, A G; Raptis, C; Capoen, B; Bouazaoui, M; Turrell, S; Khatir, S

    2010-05-19

    Raman scattering and differential scanning calorimetry (DSC) measurements have been carried out on four mixed tellurium-zinc oxide (TeO(2))(1 - x)(ZnO)(x) (x = 0.1, 0.2, 0.3, 0.4) glasses under variable temperature, with particular attention being given to the respective glass transition region. From the DSC measurements, the glass transition temperature T(g) has been determined for each glass, showing a monotonous decrease of T(g) with increasing ZnO content. The Raman study is focused on the low-frequency band of the glasses, the so-called boson peak (BP), whose frequency undergoes an abrupt decrease at a temperature T(d) very close to the respective T(g) values obtained by DSC. These results show that the BP is highly sensitive to dynamical effects over the glass transition and provides a means for an equally reliable (to DSC) determination of T(g) in tellurite glasses and other network glasses. The discontinuous temperature dependence of the BP frequency at the glass transition, along with the absence of such a behaviour by the high-frequency Raman bands (due to local atomic vibrations), indicates that marked changes of the medium range order (MRO) occur at T(g) and confirms the correlation between the BP and the MRO of glasses.

  4. Study of mercuric iodide near melting using differential scanning calorimetry Raman spectroscopy, and x-ray diffraction

    SciTech Connect

    Burger, A.; Morgan, S.; Jiang, H.; Silberman, E.; Schnieber, M.; van den Berg, L.; Keller, L.; Wagner, C.N.J.

    1987-01-01

    High-temperature studies of mercuric iodide (HgI/sub 2/) involving differential scanning calorimetry (DSC), Raman spectroscopy, and x- ray powder diffraction have failed to confirm the existence of a red-colored tetragonal high-temperature phase called ..cap alpha.. '-HgI/sub 2/ reported by S.N. Toubektsis et al., (S.N. Toubektsis, E.K. Polychroniadis, and N.A. Economou, J. Appl. Phys., 58(5) (1985) 2070), using DSC measurements. The multiple DSC peaks near melting reported by Toubektsis are found by the present authors only if the sample is heated in a stainless-steel container. Using a Pyrex container or inserting a platinum foil between the HgI/sub 2/ and the stainless-steel container yields only one sharp, single DSC peak at the melting point. The nonexistence of the ..cap alpha..' phase is confirmed by high- temperature x-ray diffraction and Raman spectroscopy performed in the vicinity of the melting point which clearly indicate the existence of the yellow orthorhombic ..beta..-HgI/sub 2/ phase only. The experimental high-temperature DSC, Raman, and x-ray diffraction data are presented and discussed. 14 refs., 8 figs., 2 tabs.

  5. A study of the relationship between water and anions of the Hofmeister series using pressure perturbation calorimetry.

    PubMed

    Bye, Jordan W; Falconer, Robert J

    2015-06-07

    Pressure perturbation calorimetry (PPC) was used to study the relationship between water and sodium salts with a range of different anions. At temperatures around 25 °C the heat on pressurisation (ΔQ) from 1 to 5 bar was negative for all solutions relative to pure water. The raw data showed that as the temperature rose, the gradient was positive relative to pure water and the transition temperature where ΔQ was zero was related to anion surface charge density and was more pronounced for the low-charge density anions. A three component model was developed comprising bulk water, the hydration layer and the solute to calculate the molar expansivity of the hydration layer around the ions in solution. The calculated molar expansivities of water in the hydration layer around the ions were consistently less than pure water. ΔQ at different disodium hydrogen phosphate concentrations showed that the change in molar enthalpy relative to pure water was not linear even as it approached infinite dilution suggesting that while hydration layers can be allocated to the water around ions this does not rule out interactions between water and ions extending beyond the immediate hydration layer.

  6. Structure and Energetics of Encapsidated DNA in Bacteriophage HK97 Studied by Scanning Calorimetry and Cryo-electron Microscopy

    PubMed Central

    Duda, Robert L.; Ross, Philip D.; Cheng, Naiqian; Firek, Brian A.; Hendrix, Roger W.; Conway, James F.; Steven, Alasdair C.

    2009-01-01

    Encapsidation of duplex DNA by bacteriophages represents an extreme case of genome condensation, reaching near-crystalline concentrations of DNA. The HK97 system is well suited to study this phenomenon in view of detailed knowledge of its capsid structure. To characterize the interactions involved, we combined calorimetry with cryo-EM and native gel electrophoresis. We found that, as in other phages, HK97 DNA is organized in coaxially wound nested shells. When scanned in buffer containing 1mM [Mg++], filled capsids exhibit a complex thermal profile between 82° and 96°, to which DNA melting and capsid denaturation both contribute. In the absence of (unbound) [Mg++], DNA melting shifts to lower temperatures and the two events are resolved. Filled capsids release their DNA at temperatures well below the onset of DNA melting or capsid denaturation. On heating, the internal pressure increases, causing the DNA to exit – probably, via the portal vertex; the capsid, although largely intact, sustains local damage that leads to an earlier onset of thermal denaturation. Filled capsids differ structurally from empty capsids in the curvature of their protein shell, a change attributable to outwards pressure exerted by the DNA. We propose that this transition is sensed by the portal which is embedded in the capsid wall, whereupon the portal's structure and its interactions with terminase, the packaging enzyme, are altered, thus signaling that packaging is at or approaching completion. PMID:19540242

  7. Transformation relaxation and aging in a CuZnAl shape-memory alloy studied by modulated differential scanning calorimetry

    SciTech Connect

    Wei, Z.G.

    1998-11-01

    The reverse martensitic transformation and aging processes in a polycrystalline Cu-23.52 at. pct Zn-9.65 at. pct Al shape-memory alloy have been studied using the recently developed modulated differential scanning calorimetry (MDSC) technique, and some new findings are obtained. By separating the nonreversing heat flow from the reversing heat flow, MDSC can better characterize the thermodynamic, kinetic, and hysteretic feature of thermoelastic martensitic transformations. Two kinds of exothermal relaxation peaks have been identified and separated from the endothermal reverse martensitic transformations: one is associated with the movement of twin interfaces or martensite-parent interfaces, and another is due to the atomic reordering in the parent phase via a vacancy mechanism. The martensite aging processes have been examined, and two stages of the aging process has been distinguished: the first stage of aging is characterized by the stabilization of martensite, as manifested in the increase in the reversing enthalpy of the reverse martensitic transformation and in the transformation temperatures, and the second stage, is in fact, the decomposition of the martensite on prolonged aging, accompanied by a decrease in the transformation enthalpy. The results suggest that the mechanisms of the relaxation in the martensite and in the parent phase may be quite different.

  8. Differential scanning calorimetry.

    PubMed

    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.

  9. Thermodynamic Study of Interactions Between ZnO and ZnO Binding Peptides Using Isothermal Titration Calorimetry.

    PubMed

    Limo, Marion J; Perry, Carole C

    2015-06-23

    While material-specific peptide binding sequences have been identified using a combination of combinatorial methods and computational modeling tools, a deep molecular level understanding of the fundamental principles through which these interactions occur and in some instances modify the morphology of inorganic materials is far from being fully realized. Understanding the thermodynamic changes that occur during peptide-inorganic interactions and correlating these to structural modifications of the inorganic materials could be the key to achieving and mastering control over material formation processes. This study is a detailed investigation applying isothermal titration calorimetry (ITC) to directly probe thermodynamic changes that occur during interaction of ZnO binding peptides (ZnO-BPs) and ZnO. The ZnO-BPs used are reported sequences G-12 (GLHVMHKVAPPR), GT-16 (GLHVMHKVAPPR-GGGC), and alanine mutants of G-12 (G-12A6, G-12A11, and G-12A12) whose interaction with ZnO during solution synthesis studies have been extensively investigated. The interactions of the ZnO-BPs with ZnO yielded biphasic isotherms comprising both an endothermic and an exothermic event. Qualitative differences were observed in the isothermal profiles of the different peptides and ZnO particles studied. Measured ΔG values were between -6 and -8.5 kcal/mol, and high adsorption affinity values indicated the occurrence of favorable ZnO-BP-ZnO interactions. ITC has great potential in its use to understand peptide-inorganic interactions, and with continued development, the knowledge gained may be instrumental for simplification of selection processes of organic molecules for the advancement of material synthesis and design.

  10. Scintillator plate calorimetry

    SciTech Connect

    Price, L.E.

    1990-01-01

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

  11. Conformational study of red kidney bean (Phaseolus vulgaris L.) protein isolate (KPI) by tryptophan fluorescence and differential scanning calorimetry.

    PubMed

    Yin, Shou-Wei; Tang, Chuan-He; Yang, Xiao-Quan; Wen, Qi-Biao

    2011-01-12

    Fluorescence and differential scanning calorimetry (DSC) were used to study changes in the conformation of red kidney bean (Phaseolus vulgaris L.) protein isolate (KPI) under various environmental conditions. The possible relationship between fluorescence data and DSC characteristics was also discussed. Tryptophan fluorescence and fluorescence quenching analyses indicated that the tryptophan residues in KPI, exhibiting multiple fluorophores with different accessibilities to acrylamide, are largely buried in the hydrophobic core of the protein matrix, with positively charged side chains close to at least some of the tryptophan residues. GdnHCl was more effective than urea and SDS in denaturing KPI. SDS and urea caused variable red shifts, 2-5 nm, in the emission λ(max), suggesting the conformational compactness of KPI. The result was further supported by DSC characteristics that a discernible endothermic peak was still detected up to 8 M urea or 30 mM SDS, also evidenced by the absence of any shift in emission maximum (λ(max)) at different pH conditions. Marked decreases in T(d) and enthalpy (ΔH) were observed at extreme alkaline and/or acidic pH, whereas the presence of NaCl resulted in higher T(d) and ΔH, along with greater cooperativity of the transition. Decreases in T(d) and ΔH were observed in the presence of protein perturbants, for example, SDS and urea, indicating partial denaturation and decrease in thermal stability. Dithiothreitol and N-ethylmaleimide have a slight effect on the thermal properties of KPI. Interestingly, a close linear relationship between the T(d) (or ΔH) and the λ(max) was observed for KPI in the presence of 0-6 M urea.

  12. Scintillator materials for calorimetry

    SciTech Connect

    Weber, M.J.

    1994-09-01

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

  13. Phase Polymorphism of [Mn(DMSO)6](ClO4)2 Studied by Differential Scanning Calorimetry

    NASA Astrophysics Data System (ADS)

    Migdał-Mikuli, Anna; Szostak, Elżbieta

    2005-04-01

    Six solid phases of [Mn(DMSO)6](ClO4)2 have been detected by differential scanning calorimetry. The phase transitions were found between the following solid phases: stable KIc ↔ stable KIb at TC5 = 225 K, metastable KIII ↔ metastable KII at TC4 = 322 K, stable KIb ↔ stable KIa at TC3 = 365 K, metastable KII↔overcooled K0 at TC2 = 376 K and stable KIa→stable K0 at TC1 = 379 K. The title compound melts at Tm = 488 K.

  14. Isothermal titration calorimetry study of a bistable supramolecular system: reversible complexation of cryptand[2.2.2] with potassium ions.

    PubMed

    del Rosso, Maria G; Ciesielski, Artur; Colella, Silvia; Harrowfield, Jack M; Samorì, Paolo

    2014-09-15

    Isothermal titration calorimetry (ITC) is used to investigate the thermodynamics of the complexation of potassium ions by 1,10-diaza-4,7,13,16,21,24-hexaoxabicyclo[8.8.8]hexacosane (cryptand[2.2.2]) in aqueous solution. By changing the pH of the solution it was possible to trigger the reversible complexation/decomplexation of the cryptand in consecutive in situ experiments and to assess for the first time the use of ITC to monitor the thermodynamics of a bistable system.

  15. Recent developments in silicon calorimetry

    SciTech Connect

    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.

  16. An isothermal titration and differential scanning calorimetry study of the G-quadruplex DNA-insulin interaction.

    PubMed

    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.

  17. Differential scanning calorimetry (DSC) of semicrystalline polymers.

    PubMed

    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.

  18. Liquid scintillator tiles for calorimetry

    SciTech Connect

    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.

  19. 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.

  20. Calorimetry study of the synthesis of amorphous Ni-Ti alloys by mechanical alloying. [Ni33 Ti67

    SciTech Connect

    Schwarz, R.B.; Petrich, R.R.

    1988-01-01

    We synthesized amorphous Ni/sub 33/Ti/sub 67/ alloy powder by ball milling (a) a mixture of elemental nickel and titanium powders and (b) powders of the crystalline intermetallic NiTi/sub 2/. We characterized the reaction products as a function of ball-milling time by differential scanning calorimetry and x-ray diffraction. The measurements suggest that in process (a) the amorphous alloy forms by a solid-state interdiffusion reaction at the clean Ni/Ti interfaces generated by the mechanical attrition. In process (b), the crystalline alloy powder stores energy in the form of chemical disorder and lattice and point defects. The crystal-to-amorphous transformation occurs when the stored energy reaches a critical value. The achievement of the critical stored energy competes with the dynamic recovery of the lattice. 23 refs., 7 figs.

  1. Phase Polymorphism of [Cd(DMSO)6](ClO4)2 Studied by Differential Scanning Calorimetry

    NASA Astrophysics Data System (ADS)

    Migdał-Mikuli, A.; Mikuli, E.; Szostak, E.; Serwónska, J.

    2003-06-01

    Five phase transitions of [Cd(DMSO)6](ClO4)2 have been detected by differential scanning calorimetry, namely the three reversible transitions: stable KIa ↔ stable KIb at TC4 = 242 K, due to a change of the crystal structure, metastable KII ↔ metastable KIII at TC3 = 318 K, and metastable KII ↔ overcooled K0 at TC2 = 347 K, one irreversible transition: KIa ↔ K0 at TC1 = 376 K, and melting at Tt = 465 K. From the enthalpy changes of these transitions it can be concluded that K0 is a solid rotational phase and KII and KIII are most probably solid phases with a high degree of orientational disorder. The phases K0, KII, and KIII form an enantiotropic system, but they are metastable in relation to the phases KIa and KIb in the whole temperature range, so they form the monotropic system with them.

  2. High-Pressure Raman and Calorimetry Studies of Vanadium(III) Alkyl Hydrides for Kubas-Type Hydrogen Storage.

    PubMed

    Morris, Leah; Trudeau, Michel L; Reed, Daniel; Book, David; Antonelli, David M

    2016-03-16

    Reversible hydrogen storage under ambient conditions has been identified as a major bottleneck in enabling a future hydrogen economy. Herein, we report an amorphous vanadium(III) alkyl hydride gel that binds hydrogen through the Kubas interaction. The material possesses a gravimetric adsorption capacity of 5.42 wt % H2 at 120 bar and 298 K reversibly at saturation with no loss of capacity after ten cycles. This corresponds to a volumetric capacity of 75.4 kgH2  m(-3) . Raman experiments at 100 bar confirm that Kubas binding is involved in the adsorption mechanism. The material possesses an enthalpy of H2 adsorption of +0.52 kJ mol(-1) H2 , as measured directly by calorimetry, and this is practical for use in a vehicles without a complex heat management system.

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

    PubMed

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

    2013-10-21

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

  4. Thermal decomposition study of monovarietal extra virgin olive oil by simultaneous thermogravimetry/differential scanning calorimetry: relation with chemical composition.

    PubMed

    Vecchio, Stefano; Cerretani, Lorenzo; Bendini, Alessandra; Chiavaro, Emma

    2009-06-10

    Thermal decomposition of 12 monovarietal extra virgin olive oils from different geographical origins (eight from Italy, two from Spain, and the others from Tunisia) was evaluated by simultaneous thermogravimetry (TG) and differential scanning calorimetry (DSC) analyses. All extra virgin olive oils showed a complex multistep decomposition pattern with the first step that exhibited a quite different profile among samples. Thermal properties of the two peaks obtained by the deconvolution of the first step of decomposition by DSC were related to the chemical composition of the samples (triacylglycerols, fatty acids, total phenols and antioxidant activity). Onset temperatures of the thermal decomposition transition and T(p) values of both deconvoluted peaks as well as the sum of enthalpy were found to exhibit statistically significant correlations with chemical components of the samples, in particular palmitic and oleic acids and related triacylglycerols. Activation energy values of the second deconvoluted peak obtained by the application of kinetic procedure to the first step of decomposition were also found to be highly statistically correlated to the chemical composition, and a stability scale among samples was proposed on the basis of its values.

  5. Temperature dependence of isothermal curing reaction of epoxy resin studied by modulated differential scanning calorimetry and infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Yamasaki, Hideki; Morita, Shigeaki

    2016-11-01

    The isothermal curing reaction of bisphenol A diglycidyl ether epoxy (BADGE) resin with dimethyl diamino methane (DDM) hardener was investigated by means of modulated differential scanning calorimetry (MDSC) and infrared (IR) spectroscopy at 90, 100 and 120 °C. It was confirmed that the behavior of the bands assigned to the epoxy group, ether group, secondary amine and tertiary amine were different depending on temperature. At stoichiometric amounts of DDM and BADGE, the reaction at 90 and 100 °C compared with that at 120 °C, the oxirane or glycidyl group of epoxy resin and the secondary amine group were left even if reached at the end point of the reaction, and those reaction proceed as diffusion control continues longer. The reaction between 90 and 100 °C, it was different from the reactivity of the epoxy resin, various amino groups and ether group. Hence, the cured epoxy resin had a different composition. Moreover, it was also verified that the reactivity of the various amino groups and the etherification were difference, therefore, it was suggested that the cross-linkage construction of the cured resin at different temperature was different.

  6. Phase Polymorphism of [Ni(DMSO)6](ClO4)2 Studied by Differential Scanning Calorimetry

    NASA Astrophysics Data System (ADS)

    Migdał-Mikuli, Anna; Szostak, Elżbieta

    2007-02-01

    Six solid phases of [Ni(DMSO)6](ClO4)2 have been detected by differential scanning calorimetry (DSC). The five phase transitions were detected between the following solid phases: metastable KIII ↔ undercooled K0 at TC5 = 326 K, stable KIb → stable KIa at TC4 = 350 K, metastable KII ↔ undercooled KI at TC3 = 353 K, stable KIa → stable KI at TC2 = 365 K and stable KI → stable K0 at TC1 = 380 K. At Tm2 = 459 K the title compound partially dissolves in DMSO, which arises from the decomposition of [Ni(DMSO)6](ClO4)2 to [Ni(DMSO)5](ClO4)2, and at Tm1 = 526 K created in this way a substance which completely melts. From the entropy changes at the melting point and at phase transitions it can be concluded that the phases K0 and undercooled K0 are orientationally dynamically disordered crystals. The stable phases KI, KIa, KIb and the metastable phases KII and KIII are more or less ordered solids.

  7. Theoretical Aspects of Differential Scanning Calorimetry as a Tool for the Studies of Equilibrium Thermodynamics in Pharmaceutical Solid Phase Transitions.

    PubMed

    Faroongsarng, Damrongsak

    2016-06-01

    Although differential scanning calorimetry (DSC) is a non-equilibrium technique, it has been used to gain energetic information that involves phase equilibria. DSC has been widely used to characterize the equilibrium melting parameters of small organic pharmaceutical compounds. An understanding of how DSC measures an equilibrium event could make for a better interpretation of the results. The aim of this mini-review was to provide a theoretical insight into the DSC measurement to obtain the equilibrium thermodynamics of a phase transition especially the melting process. It was demonstrated that the heat quantity obtained from the DSC thermogram (ΔH) was related to the thermodynamic enthalpy of the phase transition (ΔH (P) ) via: ΔH = ΔH (P) /(1 + K (- 1)) where K was the equilibrium constant. In melting, the solid and liquefied phases presumably coexist resulting in a null Gibbs free energy that produces an infinitely larger K. Thus, ΔH could be interpreted as ΔH (P). Issues of DSC investigations on melting behavior of crystalline solids including polymorphism, degradation impurity due to heating in situ, and eutectic melting were discussed. In addition, DSC has been a tool for determination of the impurity based on an ideal solution of the melt that is one of the official methods used to establish the reference standard.

  8. Liquid chromatography and differential scanning calorimetry studies on the states of water in polystyrene-divinylbenzene copolymer gels.

    PubMed

    Baba, Takayuki; Shibukawa, Masami; Heya, Tomoyuki; Abe, Shin-ichiro; Oguma, Koichi

    2003-08-29

    The thermal phase transition behavior of water incorporated in crosslinked polystyrene-divinylbenzene copolymer (PS-DVB) gel packings for liquid chromatography was investigated by differential scanning calorimetry. Free or bulk water, freezable bound or intermediate water, and nonfreezing water were observed for TSKgel Styrene-250 samples, while only free water and nonfreezing water were observed for TSKgel Styrene-60 samples. Freezable bound water and nonfreezing water in these gel samples were considered to be water confined in pores of the polymer gels. A liquid chromatographic method for determination of the amounts of stationary phase water was applied to the characterization of water in the PS-DVB beads in the columns and it was found out that any water in the PS-DVB gels did not function as the stationary phase contrary to the water sorbed in hydrophilic polymer gels; not only freezable bound water but also nonfreezing water in hydrophobic PS-DVB gels are similar to bulk water with respect to the affinity to the solute compounds.

  9. Studies of Highly-Ordered Heterodiantennary Mannose/Glucose-Functionalized Polymers and Concanavalin A Protein Interactions Using Isothermal Titration Calorimetry

    PubMed Central

    Nguyen, Hien M.

    2016-01-01

    Preparations of the highly-ordered monoantennary, homofunctional diantennary, and heterofunctional diantennary neoglycopolymers of a-D-mannose and β-D-glucose residues were achieved via ring-opening metathesis polymerization. Isothermal titration calorimetry measurements of these synthetic neoglycopolymers with Concanavalin A, revealed that hetero-functional diantennary architectures bearing both a-mannose and non-binding β-glucose units, poly(Man-Glc), binds to Concanavalin A (Ka = 16.1 × 106 M−1) comparably to homofunctional diantennary neoglycopolymer (Ka = 30 × 106 M−1) bearing only a-mannose unit, poly(Man-Man). In addition, poly(Man-Glc) neoglycopolymer shows a nearly five-fold increasing in binding affinity compared to monoantennary neoglycopolymer, poly(Man). Although the exact mechanism for the high binding affinity of poly(Man-Glc) to Con A is unclear, we hypothesize that the α-mannose bound to Con A might facilitate interaction of β-glucose with the extended binding site of Con A due to the close proximity of β-glucose to α-mannose residues in the designed polymerizable scaffold. PMID:26580410

  10. Calorimetry Study of the Phase Diagrams of EuNi2Ge2 and Eu2Ni3Ge5 under Pressure

    NASA Astrophysics Data System (ADS)

    Esakki Muthu, Sankaran; Braithwaite, Daniel; Salce, Bernard; Nakamura, Ai; Hedo, Masato; Nakama, Takao; Ōnuki, Yoshichika

    2016-09-01

    We report here the phase diagrams of EuNi2Ge2 and Eu2Ni3Ge5 studied by ac calorimetry under pressure using a diamond anvil cell. We follow the antiferromagnetic transition for EuNi2Ge2 up to 1.5 GPa. The sudden disappearance of magnetic order at around 2 GPa is confirmed, consistent with the probable occurrence of a first-order valence transition near that pressure. The ac calorimetry results on Eu2Ni3Ge5 clearly show two antiferromagnetic transitions, and suggest that magnetic order persists up to higher pressure than previously expected. At high pressure, where heavy-fermion behavior has been reported, the Néel temperature is decreasing, and magnetic order is expected to disappear at an extrapolated pressure of 12-14 GPa. A semi quantitative analysis of the pressure dependence of the specific heat does not show any large changes, but is compatible with a moderate enhancement of γ. The phase diagrams of Yb and Ce heavy fermion systems are compared and discussed with our system.

  11. Two-Phase Calorimetry. II. Studies on the Thermodynamics of Cesium and Strontium Extraction by Mixtures of H+CCD- and PEG-400 in FS-13

    SciTech Connect

    Zalupski, Peter R.; Herbst, R. S.; Delmau, Laetitia Helene; Martin, L. R.; Peterman, D. R.; Nash, Ken L

    2010-01-01

    Thermochemical characterization of the partitioning of cesium and strontium from nitric acid solutions into mixtures of the acid form of chlorinated cobalt dicarbollide (H+CCD-) and polyethylene glycol (PEG-400) in FS-13 diluent has been completed using isothermal titration microcalorimetry and radiotracer distribution methods. The phase transfer reaction for Cs+ is a straightforward (H+ for Cs+) cation exchange reaction. In contrast, the extraction of Sr2+ does not proceed in the absence of the co-solvent molecule PEG-400. This molecule is believed to facilitate the dehydration of the Sr2+ aquo cation to overcome its resistance to partitioning. The phase transfer reactions for both Cs+ and Sr2+ are enthalpy driven (exothermic), but partially compensated by an unfavorable entropy. The results of the calorimetry studies suggest that the PEG-400 functions as a stoichiometric phase transfer reagent rather than acting simply as a phase transfer catalyst or phase modifier. The calorimetry results also demonstrate that the extraction of Sr2+ is complex, including evidence for both the partitioning of Sr(NO3)+ and endothermic ion pairing interactions in the organic phase that contribute to the net enthalpic effect. The thermodynamics of the liquid-liquid distribution equilibria are discussed mainly considering the basic features of the ion solvation thermochemistry.

  12. Liquid scintillator tiles for calorimetry

    DOE PAGES

    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

  13. Quantum chemical study and low-temperature calorimetry of phase transition in V{sub 4}S{sub 9}Br{sub 4}

    SciTech Connect

    Kozlova, S.G. Gabuda, S.P.; Berezovskii, G.A.; Pischur, D.P.; Mironov, Y.V.; Simon, A.; Fedorov, V.E.

    2008-10-15

    The phase transition in a mixed-valence tetranuclear compound V{sub 4}S{sub 9}Br{sub 4} was studied by DFT calculations and low-temperature high-precision calorimetry. According to DFT data, the phase transition of the low-temperature modification may be accompanied by C{sub 4v}{yields}C{sub 2v} symmetry lowering and electron spin pairing. A weak exchange-correlation interaction discovered between {mu}{sub 4}-S{sup 2-} and S{sup 2-} ions in V{sub 4}S{sub 9}Br{sub 4} may play an important part in multicentered interactions. Experimental calorimetric data show that the phase transition is a displacive phase transformation. - Graphical abstract: Dysinaptic basins of electron spin pairing in low-temperature phase V{sub 4}S{sub 9}Br{sub 4} (arrows)

  14. 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.

  15. ``Ideal glassformers'' vs ``ideal glasses'': Studies of crystal-free routes to the glassy state by ``potential tuning'' molecular dynamics, and laboratory calorimetry

    NASA Astrophysics Data System (ADS)

    Kapko, Vitaliy; Zhao, Zuofeng; Matyushov, Dmitry V.; Austen Angell, C.

    2013-03-01

    The ability of some liquids to vitrify during supercooling is usually seen as a consequence of the rates of crystal nucleation (and/or crystal growth) becoming small [D. R. Uhlmann, J. Non-Cryst. Solids 7, 337 (1972), 10.1016/0022-3093(72)90269-4] - and thus a matter of kinetics. However, there is evidence dating back to the empirics of coal briquetting for maximum trucking efficiency [D. Frenkel, Physics 3, 37 (2010), 10.1103/Physics.3.37] that some object shapes find little advantage in self-assembly to ordered structures - meaning random packings prevail. Noting that key studies of non-spherical object packing have never been followed from hard ellipsoids [A. Donev, F. H. Stillinger, P. M. Chaikin, and S. Torquato, Phys. Rev. Lett. 92, 255506 (2004), 10.1103/PhysRevLett.92.255506; A. Donev, I. Cisse, D. Sachs, E. A. Variano, F. H. Stillinger, R. Connelly, S. Torquato, and P. M. Chaikin, Science 303, 990 (2004), 10.1126/science.1093010] or spherocylinders [S. R. Williams and A. P. Philipse, Phys. Rev. E 67, 051301 (2003), 10.1103/PhysRevE.67.051301] (diatomics excepted [S.-H. Chong, A. J. Moreno, F. Sciortino, and W. Kob, Phys. Rev. Lett. 94, 215701 (2005), 10.1103/PhysRevLett.94.215701] into the world of molecules with attractive forces, we have made a molecular dynamics study of crystal melting and glass formation on the Gay-Berne (G-B) model of ellipsoidal objects [J. G. Gay and B. J. Berne, J. Chem. Phys. 74, 3316 (1981), 10.1063/1.441483] across the aspect ratio range of the hard ellipsoid studies. Here, we report that in the aspect ratio range of maximum ellipsoid packing efficiency, various G-B crystalline states that cannot be obtained directly from the liquid, disorder spontaneously near 0 K and transform to liquids without any detectable enthalpy of fusion. Without claiming to have proved the existence of single component examples, we use the present observations, together with our knowledge of non-ideal mixing effects, to discuss the probable existence

  16. Reversible amorphous-crystalline phase changes in a wide range of Se1-xTex alloys studied using ultrafast differential scanning calorimetry

    NASA Astrophysics Data System (ADS)

    Vermeulen, Paul. A.; Momand, Jamo; Kooi, Bart J.

    2014-07-01

    The reversible amorphous-crystalline phase change in a chalcogenide material, specifically the Se1-xTex alloy, has been investigated for the first time using ultrafast differential scanning calorimetry. Heating rates and cooling rates up to 5000 K/s were used. Repeated reversible amorphous-crystalline phase switching was achieved by consecutively melting, melt-quenching, and recrystallizing upon heating. Using a well-conditioned method, the composition of a single sample was allowed to shift slowly from 15 at. %Te to 60 at. %Te, eliminating sample-to-sample variability from the measurements. Using Energy Dispersive X-ray Spectroscopy composition analysis, the onset of melting for different Te-concentrations was confirmed to coincide with the literature solidus line, validating the use of the onset of melting Tm as a composition indicator. The glass transition Tg and crystallization temperature Tc could be determined accurately, allowing the construction of extended phase diagrams. It was found that Tm and Tg increase (but Tg/Tm decrease slightly) with increasing Te-concentration. Contrarily, the Tc decreases substantially, indicating that the amorphous phase becomes progressively unfavorable. This coincides well with the observation that the critical quench rate to prevent crystallization increases about three orders of magnitude with increasing Te concentration. Due to the employment of a large range of heating rates, non-Arrhenius behavior was detected, indicating that the undercooled liquid SeTe is a fragile liquid. The activation energy of crystallization was found to increase 0.5-0.6 eV when the Te concentration increases from 15 to 30 at. % Te, but it ceases to increase when approaching 50 at. % Te.

  17. Reversible amorphous-crystalline phase changes in a wide range of Se(1-x)Te(x) alloys studied using ultrafast differential scanning calorimetry.

    PubMed

    Vermeulen, Paul A; Momand, Jamo; Kooi, Bart J

    2014-07-14

    The reversible amorphous-crystalline phase change in a chalcogenide material, specifically the Se1-xTex alloy, has been investigated for the first time using ultrafast differential scanning calorimetry. Heating rates and cooling rates up to 5000 K/s were used. Repeated reversible amorphous-crystalline phase switching was achieved by consecutively melting, melt-quenching, and recrystallizing upon heating. Using a well-conditioned method, the composition of a single sample was allowed to shift slowly from 15 at. %Te to 60 at. %Te, eliminating sample-to-sample variability from the measurements. Using Energy Dispersive X-ray Spectroscopy composition analysis, the onset of melting for different Te-concentrations was confirmed to coincide with the literature solidus line, validating the use of the onset of melting Tm as a composition indicator. The glass transition Tg and crystallization temperature Tc could be determined accurately, allowing the construction of extended phase diagrams. It was found that Tm and Tg increase (but Tg/Tm decrease slightly) with increasing Te-concentration. Contrarily, the Tc decreases substantially, indicating that the amorphous phase becomes progressively unfavorable. This coincides well with the observation that the critical quench rate to prevent crystallization increases about three orders of magnitude with increasing Te concentration. Due to the employment of a large range of heating rates, non-Arrhenius behavior was detected, indicating that the undercooled liquid SeTe is a fragile liquid. The activation energy of crystallization was found to increase 0.5-0.6 eV when the Te concentration increases from 15 to 30 at. % Te, but it ceases to increase when approaching 50 at. % Te.

  18. Interactions of a cationic antimicrobial (ε-polylysine) with an anionic biopolymer (pectin): an isothermal titration calorimetry, microelectrophoresis, and turbidity study.

    PubMed

    Chang, Yuhua; McLandsborough, Lynne; McClements, David Julian

    2011-05-25

    ε-Polylysine (ε-PL) is a food-grade cationic antimicrobial that is highly effective against a range of food pathogens and spoilage organisms. In compositionally complex environments, like those found in most foods and beverages, the antimicrobial activity of cationic ε-PL is likely to be impacted by its interactions with anionic components. The purpose of this study was to characterize the interactions between cationic ε-polylysine and an anionic biopolymer (high methoxyl pectin, HMP) using isothermal titration calorimetry (ITC), microelectrophoresis (ME), and turbidity measurements. ITC and ME measurements indicated that ε-PL bound to pectin, while turbidity measurements indicated that the complexes formed could be either soluble or insoluble depending on solution composition. Ionic strength and pH were also shown to affect the interactions significantly, highlighting their electrostatic origin. This study demonstrates that ε-PL can form either soluble or insoluble complexes with anionic biopolymers depending on the composition of the system. Our study provides basic knowledge that will facilitate the more rational application of ε-PL in complex food systems.

  19. Studying multisite binary and ternary protein interactions by global analysis of isothermal titration calorimetry data in SEDPHAT: application to adaptor protein complexes in cell signaling.

    PubMed

    Houtman, Jon C D; Brown, Patrick H; Bowden, Brent; Yamaguchi, Hiroshi; Appella, Ettore; Samelson, Lawrence E; Schuck, Peter

    2007-01-01

    Multisite interactions and the formation of ternary or higher-order protein complexes are ubiquitous features of protein interactions. Cooperativity between different ligands is a hallmark for information transfer, and is frequently critical for the biological function. We describe a new computational platform for the global analysis of isothermal titration calorimetry (ITC) data for the study of binary and ternary multisite interactions, implemented as part of the public domain multimethod analysis software SEDPHAT. The global analysis of titrations performed in different orientations was explored, and the potential for unraveling cooperativity parameters in multisite interactions was assessed in theory and experiment. To demonstrate the practical potential and limitations of global analyses of ITC titrations for the study of cooperative multiprotein interactions, we have examined the interactions of three proteins that are critical for signal transduction after T-cell activation, LAT, Grb2, and Sos1. We have shown previously that multivalent interactions between these three molecules promote the assembly of large multiprotein complexes important for T-cell receptor activation. By global analysis of the heats of binding observed in sets of ITC injections in different orientations, which allowed us to follow the formation of binary and ternary complexes, we observed negative and positive cooperativity that may be important to control the pathway of assembly and disassembly of adaptor protein particles.

  20. Fast scanning calorimetry studies of the glass transition in doped amorphous solid water: Evidence for the existence of a unique vicinal phase

    NASA Astrophysics Data System (ADS)

    McCartney, Stephanie A.; Sadtchenko, Vlad

    2013-02-01

    The fast scanning calorimetry (FSC) was employed to investigate glass transition phenomena in vapor deposited amorphous solid water (ASW) films doped with acetic acid, pentanol, and carbon tetrachloride. In all three cases, FSC thermograms of doped ASW films show well pronounced glass transitions at temperatures near 180 K. Systematic FSC studies of the glass transition temperature and the excess heat capacity dependence on the concentration of impurities indicate the possible existence of two distinct non-crystalline phases of H2O in binary aqueous solutions. According to our conjecture, bulk pure ASW is a glass at temperatures up to its crystallization near 205 K. However, guest molecules in the ASW matrix may be enveloped in an H2O phase which undergoes a glass transition prior to crystallization. In the case of CH3COOH, we estimate that such a viscous liquid shell contains approximately 25 H2O molecules. We discuss the implications of these findings for past studies of molecular kinetics in pure vitreous water and in binary aqueous solutions.

  1. Fast scanning calorimetry studies of the glass transition in doped amorphous solid water: evidence for the existence of a unique vicinal phase.

    PubMed

    McCartney, Stephanie A; Sadtchenko, Vlad

    2013-02-28

    The fast scanning calorimetry (FSC) was employed to investigate glass transition phenomena in vapor deposited amorphous solid water (ASW) films doped with acetic acid, pentanol, and carbon tetrachloride. In all three cases, FSC thermograms of doped ASW films show well pronounced glass transitions at temperatures near 180 K. Systematic FSC studies of the glass transition temperature and the excess heat capacity dependence on the concentration of impurities indicate the possible existence of two distinct non-crystalline phases of H2O in binary aqueous solutions. According to our conjecture, bulk pure ASW is a glass at temperatures up to its crystallization near 205 K. However, guest molecules in the ASW matrix may be enveloped in an H2O phase which undergoes a glass transition prior to crystallization. In the case of CH3COOH, we estimate that such a viscous liquid shell contains approximately 25 H2O molecules. We discuss the implications of these findings for past studies of molecular kinetics in pure vitreous water and in binary aqueous solutions.

  2. CALORIMETRY OF TRU WASTE MATERIALS

    SciTech Connect

    C. RUDY; ET AL

    2000-08-01

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

  3. From biochemistry to physiology: the calorimetry connection.

    PubMed

    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.

  4. High Data Rate Instrument Study

    NASA Technical Reports Server (NTRS)

    Schober, Wayne; Lansing, Faiza; Wilson, Keith; Webb, Evan

    1999-01-01

    The High Data Rate Instrument Study was a joint effort between the Jet Propulsion Laboratory (JPL) and the Goddard Space Flight Center (GSFC). The objectives were to assess the characteristics of future high data rate Earth observing science instruments and then to assess the feasibility of developing data processing systems and communications systems required to meet those data rates. Instruments and technology were assessed for technology readiness dates of 2000, 2003, and 2006. The highest data rate instruments are hyperspectral and synthetic aperture radar instruments which are capable of generating 3.2 Gigabits per second (Gbps) and 1.3 Gbps, respectively, with a technology readiness date of 2003. These instruments would require storage of 16.2 Terebits (Tb) of information (RF communications case of two orbits of data) or 40.5 Tb of information (optical communications case of five orbits of data) with a technology readiness date of 2003. Onboard storage capability in 2003 is estimated at 4 Tb; therefore, all the data created cannot be stored without processing or compression. Of the 4 Tb of stored data, RF communications can only send about one third of the data to the ground, while optical communications is estimated at 6.4 Tb across all three technology readiness dates of 2000, 2003, and 2006 which were used in the study. The study includes analysis of the onboard processing and communications technologies at these three dates and potential systems to meet the high data rate requirements. In the 2003 case, 7.8% of the data can be stored and downlinked by RF communications while 10% of the data can be stored and downlinked with optical communications. The study conclusion is that only 1 to 10% of the data generated by high data rate instruments will be sent to the ground from now through 2006 unless revolutionary changes in spacecraft design and operations such as intelligent data extraction are developed.

  5. Probing of the combined effect of bisquaternary ammonium antimicrobial agents and acetylsalicylic acid on model phospholipid membranes: differential scanning calorimetry and mass spectrometry studies.

    PubMed

    Kasian, N A; Pashynska, V A; Vashchenko, O V; Krasnikova, A O; Gömöry, A; Kosevich, M V; Lisetski, L N

    2014-12-01

    A model molecular biosystem of hydrated dipalmitoylphosphatidylcholine (DPPC) bilayers that mimics cell biomembranes is used to probe combined membranotropic effects of drugs by instrumental techniques of molecular biophysics. Differential scanning calorimetry reveals that doping of the DPPC model membrane with individual bisquaternary ammonium compounds (BQAC) decamethoxinum, ethonium, thionium and acetylsalicylic acid (ASA) leads to lowering of the membrane melting temperature (Tm) pointing to membrane fluidization. Combined application of the basic BQAC and acidic ASA causes an opposite effect on Tm (increase), corresponding to the membrane densification. Thus, modulation of the membranotropic effects upon combined use of the drugs studied can be revealed at the level of model membranes. Formation of noncovalent supramolecular complexes of the individual BQACs and ASA with DPPC molecules, which may be involved in the mechanism of the drug-membrane interaction at the molecular level, is demonstrated by electrospray ionization (ESI) mass spectrometry. In the ternary (DPPC + ASA + BQAC) model systems, the stable complexes of the BQAC dication with the ASA anion, which may be responsible for modulation of the membranotropic effects of the drugs, were recorded by ESI mass spectrometry. The proposed approach can be further developed for preliminary evaluation of the combined effects of the drugs at the level of model lipid membranes prior to tests on living organisms.

  6. Thermodynamic Insight into the Solvation and Complexation Behavior of U(VI) in Ionic Liquid: Binding of CMPO with U(VI) Studied by Optical Spectroscopy and Calorimetry.

    PubMed

    Wu, Qi; Sun, Taoxiang; Meng, Xianghai; Chen, Jing; Xu, Chao

    2017-03-06

    The complexation of U(VI) with octylphenyl-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO, denoted as L) in ionic liquid (IL) C4mimNTf2 was investigated by UV-vis absorption spectrophotometry and isothermal titration calorimetry. Spectro-photometric titration suggests that three successive complexes, UO2Lj(2+) (j = 1-3), formed both in "dry" (water content < 250 ppm) and "wet" (water content ≈ 12 500 ppm) ionic liquid. However, the thermodynamic parameters are distinctly different in the two ILs. In dry IL, the complexation strength between CMPO and U(VI) is much stronger, with stability constants of the respective complexes more than 1 order of magnitude higher than that in wet IL. Energetically, the complexation of U(VI) with CMPO in dry IL is mainly driven by negative enthalpies. In contrast, the complexation in wet IL is overwhelmingly driven by highly positive entropies as a result of the release of a large amount of water molecules from the solvation sphere of U(VI). Moreover, comparisons between the fitted absorption spectra of complexes in wet IL and that of extractive samples from solvent extraction have identified the speciation involved in the extraction of U(VI) by CMPO in ionic liquid. The results from this study not only offer a thermodynamic insight into the complexation behavior of U(VI) with CMPO in IL but also provide valuable information for understanding the extraction behavior in the corresponding solvent extraction system.

  7. Capillary condensation, freezing, and melting in silica nanopores: A sorption isotherm and scanning calorimetry study on nitrogen in mesoporous SBA-15

    NASA Astrophysics Data System (ADS)

    Moerz, Sebastian T.; Knorr, Klaus; Huber, Patrick

    2012-02-01

    Condensation, melting, and freezing of nitrogen in a powder of mesoporous silica grains (SBA-15) has been studied by combined volumetric sorption isotherm and scanning calorimetry measurements. Within the mean-field model of Saam and Cole for vapor condensation in cylindrical pores, a liquid nitrogen sorption isotherm is well described by a bimodal pore radius distribution. It encompasses a narrow peak centered at 3.3 nm, typical of tubular mesopores, and a significantly broader peak characteristic of micropores, located at 1 nm. The material condensed in the micropores as well as the first two adsorbed monolayers in the mesopores do not exhibit any caloric anomaly. The solidification and melting transformation affects only the pore condensate beyond approximately the second monolayer of the mesopores. Here, interfacial melting leads to a single peak in the specific-heat measurements. Homogeneous and heterogeneous freezing along with a delayering transition for partial fillings of the mesopores result in a caloric freezing anomaly similarly complex and dependent on the thermal history to that observed for argon in SBA-15. The axial propagation of the crystallization in pore space is more effective in the case of nitrogen than previously observed for argon, which we attribute to differences in the crystalline textures of the pore solids.

  8. Effect of pH on the complexation of kaempferol-4'-glucoside with three β-cyclodextrin derivatives: isothermal titration calorimetry and spectroscopy study.

    PubMed

    Zheng, Yan; Dong, Li-Na; Liu, Min; Chen, Aiju; Feng, Shangcai; Wang, Bingquan; Sun, Dezhi

    2014-01-08

    The utilization of kaempferol and its glycosides in food and pharmaceutical industries could be improved by the formation of inclusion complexes with cyclodextrins at different pH. This study explores the complexation of kaempferol-4'-glucoside with sulfobutyl ether-β-cyclodextrin (SBE-β-CD), hydroxypropyl-β-cyclodextrin (HP-β-CD), and methylated-β-cyclodextrin (M-β-CD) in phosphate buffer solutions of different pH using isothermal titration calorimetry, UV-vis absorption and proton nuclear magnetic resonance spectroscopy at 298.2 K. Experimental results showed that kaempferol-4'-glucoside binds with the three β- cyclodextrins in the same 1:1 stoichiometry. The rank order of stability constants is SBE-β-CD > HP-β-CD > M-β-CD at the same pH level and pH 6.0 > pH 7.4 > pH 9.0 for the same cyclodextrin. The binding of kaempferol-4'-glucoside with the three β-cyclodextrin derivatives is synergistically driven by enthalpy and entropy at pH 6.0 and enthalpy-driven at pH 7.4 and 9.0. The possible inclusion mode was that in the cavity of β-CD is included the planar benzopyranic-4-one part of the kaempferol-4'-glucoside.

  9. Thermodynamic insights into drug-surfactant interactions: Study of the interactions of naporxen, diclofenac sodium, neomycin, and lincomycin with hexadecytrimethylammonium bromide by using isothermal titration calorimetry.

    PubMed

    Choudhary, Sinjan; Talele, Paurnima; Kishore, Nand

    2015-08-01

    The success of drug delivery depends on the efficiency of the route of administration, which in turn relies on properties of the drug and its transport vehicle. A quantitative knowledge of association of drugs with transport vehicles is lacking when the latter are in the category of self assembled structures. The work reported in this manuscript addresses the mechanism of partitioning of naproxen, diclofenac sodium, neomycin and lincomycin in the micelles of hexadecytrimethylammonium bromide and that is quantitatively based on the measurement of thermodynamic parameters of interactions by using isothermal titration calorimetry. The addressed mechanism of partitioning is based on the identification of the type of interactions of these drugs with the surfactant micelles and monomers, along with the effect of the former on the micellization properties of the surfactant. The conclusions are based on the interpretation of the values of partitioning constant, standard molar enthalpy change, standard molar entropy change and the stoichiometry of the interaction. The results of this study have implications for deriving guidelines for the target oriented synthesis of new drugs that are to be used for effective delivery via micellar media.

  10. Determination of thermodynamic potentials and the aggregation number for micelles with the mass-action model by isothermal titration calorimetry: A case study on bile salts.

    PubMed

    Olesen, Niels Erik; Westh, Peter; Holm, René

    2015-09-01

    The aggregation number (n), thermodynamic potentials (ΔG, ΔH, ΔS) and critical micelle concentration (CMC) for 6 natural bile salts were determined on the basis of both original and previously published isothermal titration calorimetry (ITC) data. Different procedures to estimate parameters of micelles with ITC were compared to a mass-action model (MAM) of reaction type: n⋅S⇌Mn. This analysis can provide guidelines for future ITC studies of systems behaving in accordance with this model such as micelles and proteins that undergo self-association to oligomers. Micelles with small aggregation numbers, as those of bile salts, are interesting because such small aggregates cannot be characterized as a separate macroscopic phase and the widely applied pseudo-phase model (PPM) is inaccurate. In the present work it was demonstrated that the aggregation number of micelles was constant at low concentrations enabling determination of the thermodynamic potentials by the MAM. A correlation between the aggregation number and the heat capacity was found, which implies that the dehydrated surface area of bile salts increases with the aggregation number. This is in accordance with Tanford's principles of opposing forces where neighbouring molecules in the aggregate are better able to shield from the surrounding hydrophilic environment when the aggregation number increases.

  11. Binding of the alkaloid aristololactam-β-D-glucoside and daunomycin to human hemoglobin: spectroscopy and calorimetry studies.

    PubMed

    Das, Abhi; Suresh Kumar, Gopinatha

    2016-01-01

    The interaction of the plant alkaloid aristololactam-β-D-glucoside (ADG) and the anticancer agent daunomycin (DAN) with human hemoglobin was studied by different spectroscopic and calorimetric methods. The binding affinity values of ADG and DAN, estimated from spectroscopic experiments, were 3.79 × 10(4) and 6.68 × 10(4) M(-1), respectively. From circular dichroism, 3D fluorescence, and FTIR studies it was observed that, DAN induced stronger conformational changes than ADG in the protein. From synchronous fluorescence spectroscopy results, a pronounced shift in the maximum emission wavelength of tyrosine residues was observed in both cases suggesting that the drugs changed the polarity around tyrosine residues with marginal change around the tryptophan residues. The thermodynamics of the binding interaction analyzed using microcalorimetry presented single binding events that were exothermic in nature in both cases. The binding was driven by large positive standard molar entropy changes with small favorable enthalpy contributions. Negative heat capacity changes in both cases are correlated to the involvement of significant hydrophobic forces in the complexation process. The affinity of DAN to Hb was higher than that of ADG.

  12. The Application of DNA-Biosensors and Differential Scanning Calorimetry to the Study of the DNA-Binding Agent Berenil.

    PubMed

    De Abreu, Fabiane C; De Paula, Francine S; Ferreira, Danielle C M; Nascimento, Valberes B; Lopes, Julio C D; Santos, Alexandre M C; Santoro, Marcelo M; Salas, Carlos E; Goulart, Marília O F

    2008-03-03

    The in situ DNA-damaging capacity of berenil (1) has been investigated usingan electrochemical approach employing double stranded (ds) DNA-modified glassy carbonelectrode biosensors. Electrochemical voltammetric sensing of damage caused by 1 todsDNA was monitored by the appearance of peaks diagnostic of the oxidation of guanineand adenine. When 1 was incorporated directly onto the biosensor surface, DNA damagecould be observed at concentrations of additive as low as 10 μM. In contrast, when thedsDNA-modified biosensor was exposed to 1, in acetate buffer solution, the method wasmuch less sensitive and DNA damage could be detected only in the presence of 100 μMberenil. When mixed solutions of 1 and single stranded (ss) DNA, polyguanylic acid orpolyadenylic acid were submitted to voltammetric study, the oxidation signals of therespective bases decreased in a concentration-dependent manner and the major variation ofthe adenine current peak indicated preferential binding of 1 to adenine. The electrochemical results were in close agreement with those deriving from a differentialscanning calorimetric study of the DNA-berenil complex.

  13. Structural and thermodynamic analysis of the binding of tRNA(phe) by the putative anticancer alkaloid chelerythrine: Spectroscopy, calorimetry and molecular docking studies.

    PubMed

    Basu, Pritha; Payghan, Pavan V; Ghoshal, Nanda; Suresh Kumar, Gopinatha

    2016-08-01

    The interaction of the putative anticancer alkaloid chelerythrine with tRNA(phe) was characterized by spectroscopy, calorimetry and molecular docking studies. The charged iminium form of chelerythrine binds with tRNA(phe) in a cooperative mode with a binding affinity value of (4.06±0.01)×10(5)M(-1). The neutral alkanolamine form does not bind to tRNA(phe) but in the presence of high concentration of tRNA(phe) this form gets converted to the iminium form and then binds with tRNA(phe). The partial intercalative mode of binding of chelerythrine to the tRNA(phe) was characterized from the steady state anisotropy, iodide ion-induced fluorescence quenching and viscosity measurements. Chelerythrine binding induced conformational perturbations in tRNA(phe) as observed from the circular dichroism spectroscopy. The strong binding was also supported by the ethidium bromide displacement assay. The binding was favoured by both enthalpy and entropy contributions. Although the binding was dependent on the [Na(+)], non-electrostatic forces contributed predominantly to the Gibbs energy change. The negative value of the heat capacity change proposed the involvement of hydrophobic forces in the binding. Molecular docking study was carried out to decipher the details of the recognition of tRNA(phe) by chelerythrine. The study provided insights about the chelerythrine binding pockets on tRNA(phe) and marked the necessary interactions for binding of chelerythrine molecule. Partially intercalative mode of the alkaloid binding was supported by docking studies. In total, docking studies corroborated well with our experiential observations. The structural and thermodynamic results of chelerythrine binding to tRNA(phe) may be helpful to develop new RNA therapeutic agents.

  14. Combination of chemometrically assisted voltammetry, calorimetry, and circular dichroism as a new method for the study of bioinorganic substances: application to selenocystine metal complexes.

    PubMed

    Gusmão, Rui; Prohens, Rafel; Díaz-Cruz, José Manuel; Ariño, Cristina; Esteban, Miquel

    2012-02-01

    Selenium-containing compounds play an important role in antioxidant defense systems, binding to toxic metals, preventing their uptake into cells, and thus protecting cells from metal-induced formation of reactive oxygen species. Here, we present a proposal for a relatively new method as a complement to the more usual methods used in selenium studies. A systematic study of the metal-binding properties of selenocystine (SeCyst) in the presence of divalent metal cations (Cd, Co, Hg, Ni, and Zn) is reported. Isothermal titration calorimetry provides thermodynamic parameters of the systems. Titrations produced curves that could be fit reasonably well to the one set of sites model. The data clearly demonstrate that one M(2+) binds one SeCyst molecule, and the stable M(SeCyst) complex is formed under these conditions. The order of the SeCyst binding constant for the metal ions is Hg(2+) > Cd(2+) ~ Zn(2+) > Ni(2+)> Co(2+). Cadmium ion was selected as a modulator for the behavior of SeCyst in the presence of a nonessential metal, and zinc was selected for the case of an essential element. These interactions of SeCyst with Cd(2+) and Zn(2+), either individually or combined, were studied in aqueous buffered solutions at physiological pH by differential pulse polarography and circular dichroism spectroscopy. Furthermore, recently developed chemometric tools were applied to differential pulse polarography data obtained in mixtures of SeCyst and glutathione in the presence of Cd(2+) at physiological pH.

  15. Determining enzyme kinetics via isothermal titration calorimetry.

    PubMed

    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.

  16. The differences in binding 12-carbon aliphatic ligands by bovine β-lactoglobulin isoform A and B studied by isothermal titration calorimetry and X-ray crystallography.

    PubMed

    Loch, Joanna I; Bonarek, Piotr; Polit, Agnieszka; Swiątek, Śylwia; Dziedzicka-Wasylewska, Marta; Lewiński, Krzysztof

    2013-08-01

    Isoforms A (LGB-A) and B (LGB-B) of bovine lactoglobulin, the milk protein, differ in positions 64 (D↔G) and 118 (V↔A). Interactions of LGB-A and LGB-B with sodium dodecyl sulfate (SDS), dodecyltrimethylammonium chloride (DTAC) and lauric acid (LA), 12-carbon ligands possessing differently charged polar groups, were investigated using isothermal titration calorimetry and X-ray crystallography, to study the proton linkage phenomenon and to distinguish between effects related to different isoforms and different ligand properties. The determined values of ΔS and ΔH revealed that for all ligands, binding is entropically driven. The contribution from enthalpy change is lower and shows strong dependence on type of buffer that indicates proton release from the protein varying with protein isoform and ligand type and involvement of LA and Asp64 (in isoform A) in this process. The ligand affinities for both isoforms were arranged in the same order, DTAC < LA < SDS, and were systematically lower for variant B. The entropy change of the complexation process was always higher for isoform A, but these values were compensated by changes in enthalpy, resulting in almost identical ΔG for complexes of both isoforms. The determined crystal structures showed that substitution in positions 64 and 118 did not influence the overall structure of LGB complexes. The chemical character of the ligand polar group did not affect the position of its aliphatic chain in protein β-barrel, indicating a major role of hydrophobic interactions in ligand binding that prevailed even with the repulsion between positively charged DTAC and lysine residues located at binding site entrance.

  17. Calorimetry Triggering in ATLAS

    SciTech Connect

    Igonkina, O.; Achenbach, R.; Adragna, P.; Aharrouche, M.; Alexandre, G.; Andrei, V.; Anduaga, X.; Aracena, I.; Backlund, S.; Baines, J.; Barnett, B.M.; Bauss, B.; Bee, C.; Behera, P.; Bell, P.; Bendel, M.; Benslama, K.; Berry, T.; Bogaerts, A.; Bohm, C.; Bold, T.; /UC, Irvine /AGH-UST, Cracow /Birmingham U. /Barcelona, IFAE /CERN /Birmingham U. /Rutherford /Montreal U. /Santa Maria U., Valparaiso /DESY /DESY, Zeuthen /Geneva U. /City Coll., N.Y. /Barcelona, IFAE /CERN /Birmingham U. /Kirchhoff Inst. Phys. /Birmingham U. /Lisbon, LIFEP /Rio de Janeiro Federal U. /City Coll., N.Y. /Birmingham U. /Copenhagen U. /Copenhagen U. /Brookhaven /Rutherford /Royal Holloway, U. of London /Pennsylvania U. /Montreal U. /SLAC /CERN /Michigan State U. /Chile U., Catolica /City Coll., N.Y. /Oxford U. /La Plata U. /McGill U. /Mainz U., Inst. Phys. /Hamburg U. /DESY /DESY, Zeuthen /Geneva U. /Queen Mary, U. of London /CERN /Rutherford /Rio de Janeiro Federal U. /Birmingham U. /Montreal U. /CERN /Kirchhoff Inst. Phys. /Liverpool U. /Royal Holloway, U. of London /Pennsylvania U. /Kirchhoff Inst. Phys. /Geneva U. /Birmingham U. /NIKHEF, Amsterdam /Rutherford /Royal Holloway, U. of London /Rutherford /Royal Holloway, U. of London /AGH-UST, Cracow /Mainz U., Inst. Phys. /Mainz U., Inst. Phys. /Birmingham U. /Hamburg U. /DESY /DESY, Zeuthen /Geneva U. /Kirchhoff Inst. Phys. /Michigan State U. /Stockholm U. /Stockholm U. /Birmingham U. /CERN /Montreal U. /Stockholm U. /Arizona U. /Regina U. /Regina U. /Rutherford /NIKHEF, Amsterdam /Kirchhoff Inst. Phys. /DESY /DESY, Zeuthen /City Coll., N.Y. /University Coll. London /Humboldt U., Berlin /Queen Mary, U. of London /Argonne /LPSC, Grenoble /Arizona U. /Kirchhoff Inst. Phys. /Birmingham U. /Antonio Narino U. /Hamburg U. /DESY /DESY, Zeuthen /Kirchhoff Inst. Phys. /Birmingham U. /Chile U., Catolica /Indiana U. /Manchester U. /Kirchhoff Inst. Phys. /Rutherford /City Coll., N.Y. /Stockholm U. /La Plata U. /Antonio Narino U. /Queen Mary, U. of London /Kirchhoff Inst. Phys. /Antonio Narino U. /Pavia U. /City Coll., N.Y. /Mainz U., Inst. Phys. /Mainz U., Inst. Phys. /Pennsylvania U. /Barcelona, IFAE /Barcelona, IFAE /Chile U., Catolica /Genoa U. /INFN, Genoa /Rutherford /Barcelona, IFAE /Nevis Labs, Columbia U. /CERN /Antonio Narino U. /McGill U. /Rutherford /Santa Maria U., Valparaiso /Rutherford /Chile U., Catolica /Brookhaven /Oregon U. /Mainz U., Inst. Phys. /Barcelona, IFAE /McGill U. /Antonio Narino U. /Antonio Narino U. /Kirchhoff Inst. Phys. /Sydney U. /Rutherford /McGill U. /McGill U. /Pavia U. /Genoa U. /INFN, Genoa /Kirchhoff Inst. Phys. /Kirchhoff Inst. Phys. /Mainz U., Inst. Phys. /Barcelona, IFAE /SLAC /Stockholm U. /Moscow State U. /Stockholm U. /Birmingham U. /Kirchhoff Inst. Phys. /DESY /DESY, Zeuthen /Birmingham U. /Geneva U. /Oregon U. /Barcelona, IFAE /University Coll. London /Royal Holloway, U. of London /Birmingham U. /Mainz U., Inst. Phys. /Birmingham U. /Birmingham U. /Oregon U. /La Plata U. /Geneva U. /Chile U., Catolica /McGill U. /Pavia U. /Barcelona, IFAE /Regina U. /Birmingham U. /Birmingham U. /Kirchhoff Inst. Phys. /Oxford U. /CERN /Kirchhoff Inst. Phys. /UC, Irvine /UC, Irvine /Wisconsin U., Madison /Rutherford /Mainz U., Inst. Phys. /CERN /Geneva U. /Copenhagen U. /City Coll., N.Y. /Wisconsin U., Madison /Rio de Janeiro Federal U. /Wisconsin U., Madison /Stockholm U. /University Coll. London

    2011-12-08

    The ATLAS experiment is preparing for data taking at 14 TeV collision energy. A rich discovery physics program is being prepared in addition to the detailed study of Standard Model processes which will be produced in abundance. The ATLAS multi-level trigger system is designed to accept one event in 2/10{sup 5} to enable the selection of rare and unusual physics events. The ATLAS calorimeter system is a precise instrument, which includes liquid Argon electro-magnetic and hadronic components as well as a scintillator-tile hadronic calorimeter. All these components are used in the various levels of the trigger system. A wide physics coverage is ensured by inclusively selecting events with candidate electrons, photons, taus, jets or those with large missing transverse energy. The commissioning of the trigger system is being performed with cosmic ray events and by replaying simulated Monte Carlo events through the trigger and data acquisition system.

  18. The use of calorimetry in nuclear materials management

    SciTech Connect

    Nutter, J.D.; O`Hara, F.A.; Rodenburg, W.W.

    1996-07-01

    A calorimeter is a device to measure evolved or adsorbed heat. For our purposes, the heat measured is that associated with radioactive decay and the unit of measurement is the watt. Each time an atom decays, energy is released and absorbed by the surroundings and heat generated. For each isotope, this heat is a constant related to the energy of the decay particles and the half-life of the isotope. A point which is often overlooked is that calorimetry is one of the oldest techniques known for measuring radioactivity. In 1903, Pierre Curie and A. Laborde used a twin microcalorimeter to determine that one gram of radium generates about 100 calories per hour. Several months later, Curie and Dewar used liquid oxygen and hydrogen to show that the amount of energy developed by radium and other radioactive elements did not depend on temperature. At that time, this observation was extremely important. It indicated that the nature of radioactivity is entirely different and cannot be compared with any known phenomena. In all other thermal processes known in physics and chemistry, the rate at which heat is developed changes with temperature. In 1942, Monsanto was asked by General Leslie Groves, Head of the Manhattan Project, to accept the responsibility for the chemistry and metallurgy of radioactive polonium. Late in 1943, two Monsanto scientists began a study of the half-life of polonium-210 using calorimetry.

  19. 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.

  20. Efficiency of the photoprocesses leading to singlet oxygen (1 delta g) generation by alpha-terthienyl: optical absorption, optoacoustic calorimetry and infrared luminescence studies.

    PubMed

    Scaiano, J C; Redmond, R W; Mehta, B; Arnason, J T

    1990-10-01

    The triplet energy of alpha-terthienyl has been determined by heavy atom-induced optical absorption: the value of 39.7 +/- 1.5 kcal/mol is consistent with earlier energy transfer work. Combining this result with calorimetric data from optoacoustic calorimetry indicates that intersystem crossing occurs with at least 90% efficiency in polar and non-polar solvents. The quantum yields for singlet oxygen formation via energy transfer from triplet alpha-terthienyl have been obtained from time-resolved measurements of its IR phosphorescence: these yields are in the 0.6-0.8 range in non-polar and polar (hydroxylic and non-hydroxylic) solvents.

  1. A comparative study of capillary electrophoresis and isothermal titration calorimetry for the determination of binding constant of human serum albumin to monoclonal antibody.

    PubMed

    Andrási, Melinda; Lehoczki, Gábor; Nagy, Zoltán; Gyémánt, Gyöngyi; Pungor, András; Gáspár, Attila

    2015-06-01

    This paper focuses on the investigation of the interactions between the anti-HSA-mAb and its protein antigen using CZE, ACE, and isothermal titration calorimetry. The CZE revealed the formation of the anti-HSA-mAb·HSA and anti-HSA-mAb·(HSA)2 complexes and the binding constants determined by plotting the amount of the bound anti-HSA-mAb as a function of the concentration of HSA. The ACE provided information on the binding strength from the change in effective electrophoretic mobility of the anti-HSA-mAb. These two separation techniques estimated the presence of two binding sites. The equilibrium dissociation constant values obtained by CZE and ACE were found to be 2.26 × 10(-6) M for anti-HSA-mAb·HSA, 1.22 × 10(-6) M for anti-HSA-mAb·(HSA)2 and 4.45 × 10(-8) M for anti-HSA-mAb·HSA, 1.08 × 10(-7) M for anti-HSA-mAb·(HSA)2 , respectively. The dissociation constant data obtained by ACE were in congruence with the values obtained by isothermal titration calorimetry (2.74 × 10(-8) M, 1.04 × 10(-7) M).

  2. Dimyristoylphosphatidylcholine/C16:0-ceramide binary liposomes studied by differential scanning calorimetry and wide- and small-angle x-ray scattering.

    PubMed Central

    Holopainen, J M; Lemmich, J; Richter, F; Mouritsen, O G; Rapp, G; Kinnunen, P K

    2000-01-01

    Ceramide has recently been established as a central messenger in the signaling cascades controlling cell behavior. Physicochemical studies have revealed a strong tendency of this lipid toward phase separation in mixtures with phosphatidylcholines. The thermal phase behavior and structure of fully hydrated binary membranes composed of dimyristoylphosphatidylcholine (DMPC) and N-palmitoyl-ceramide (C16:0-ceramide, up to a mole fraction X(cer) = 0.35) were resolved in further detail by high-sensitivity differential scanning calorimetry (DSC) and x-ray diffraction. Both methods reveal very strong hysteresis in the thermal phase behavior of ceramide-containing membranes. A partial phase diagram was constructed based on results from a combination of these two methods. DSC heating scans show that with increased X(cer) the pretransition temperature T(p) first increases, whereafter at X(cer) > 0.06 it can no longer be resolved. The main transition enthalpy DeltaH remains practically unaltered while its width increases significantly, and the upper phase boundary temperature of the mixture shifts to approximately 63 degrees C at X(cer) = 0.30. Upon cooling, profound phase separation is evident, and for all of the studied compositions there is an endotherm in the region close to the T(m) for DMPC. At X(cer) >/= 0.03 a second endotherm is evident at higher temperatures, starting at 32.1 degrees C and reaching 54.6 degrees C at X(cer) = 0.30. X-ray small-angle reflection heating scans reveal a lamellar phase within the temperature range of 15-60 degrees C, regardless of composition. The pretransition is observed up to X(cer) < 0.18, together with an increase in T(p). In the gel phase the lamellar repeat distance d increases from approximately 61 A at X(cer) = 0. 03, to 67 A at X(cer) = 0.35. In the fluid phase increasing X(cer) from 0.06 to 0.35 augments d from 61 A to 64 A. An L(beta')/L(alpha) (ripple/fluid) phase coexistence region is observed at high temperatures (from 31 to

  3. Application of solution calorimetry in pharmaceutical and biopharmaceutical research.

    PubMed

    Royall, P G; Gaisford, S

    2005-06-01

    In solution calorimetry the heat of solution (Delta(sol)H) is recorded as a solute (usually a solid) dissolves in an excess of solvent. Such measurements are valuable during all the phases of pharmaceutical formulation and the number of applications of the technique is growing. For instance, solution calorimetry is extremely useful during preformulation for the detection and quantification of polymorphs, degrees of crystallinity and percent amorphous content; knowledge of all of these parameters is essential in order to exert control over the manufacture and subsequent performance of a solid pharmaceutical. Careful experimental design and data interpretation also allows the measurement of the enthalpy of transfer (Delta(trans)H) of a solute between two phases. Because solution calorimetry does not require optically transparent solutions, and can be used to study cloudy or turbid solutions or suspensions directly, measurement of Delta(trans)H affords the opportunity to study the partitioning of drugs into, and across, biological membranes. It also allows the in-situ study of cellular systems. Furthermore, novel experimental methodologies have led to the increasing use of solution calorimetry to study a wider range of phenomena, such as the precipitation of drugs from supersaturated solutions or the formation of liposomes from phospholipid films. It is the purpose of this review to discuss some of these applications, in the context of pharmaceutical formulation and preformulation, and highlight some of the potential future areas where solution calorimetry might find applications.

  4. Non-additive response of blends of rice and potato starch during heating at intermediate water contents: A differential scanning calorimetry and proton nuclear magnetic resonance study.

    PubMed

    Bosmans, Geertrui M; Pareyt, Bram; Delcour, Jan A

    2016-02-01

    The impact of different hydration levels, on gelatinization of potato starch (PS), rice starch (RS) and a 1:1 blend thereof, was investigated by differential scanning calorimetry and related to nuclear magnetic resonance proton distributions of hydrated samples, before and after heating. At 20% or 30% hydration, the visual appearance of all samples was that of a wet powder, and limited, if any, gelatinization occurred upon heating. At 30% hydration, changes in proton distributions were observed and related to plasticization of amorphous regions in the granules. At 50% hydration, the PS-RS blend appeared more liquid-like than other hydrated samples and showed more pronounced gelatinization than expected based on additive behavior of pure starches. This was due to an additional mobile water fraction in the unheated PS-RS blend, originating from differences in water distribution due to altered stacking of granules and/or altered hydration of PS due to presence of cations in RS.

  5. Application of isothermal titration calorimetry for characterizing thermodynamic parameters of biomolecular interactions: peptide self-assembly and protein adsorption case studies.

    PubMed

    Kabiri, Maryam; Unsworth, Larry D

    2014-10-13

    The complex nature of macromolecular interactions usually makes it very hard to identify the molecular-level mechanisms that ultimately dictate the result of these interactions. This is especially evident in the case of biological systems, where the complex interaction of molecules in various situations may be responsible for driving biomolecular interactions themselves but also has a broader effect at the cell and/or tissue level. This review will endeavor to further the understanding of biomolecular interactions utilizing the isothermal titration calorimetry (ITC) technique for thermodynamic characterization of two extremely important biomaterial systems, viz., peptide self-assembly and nonfouling polymer-modified surfaces. The advantages and shortcomings of this technique will be presented along with a thorough review of the recent application of ITC to these two areas. Furthermore, the controversies associated with the enthalpy-entropy compensation effect as well as thermodynamic equilibrium state for such interactions will be discussed.

  6. Characteristics of rose hip (Rosa canina L.) cold-pressed oil and its oxidative stability studied by the differential scanning calorimetry method.

    PubMed

    Grajzer, Magdalena; Prescha, Anna; Korzonek, Katarzyna; Wojakowska, Anna; Dziadas, Mariusz; Kulma, Anna; Grajeta, Halina

    2015-12-01

    Two new commercially available high linolenic oils, pressed at low temperature from rose hip seeds, were characterised for their composition, quality and DPPH radical scavenging activity. The oxidative stability of oils was assessed using differential scanning calorimetry (DSC). Phytosterols, tocopherols and carotenoids contents were up to 6485.4; 1124.7; and 107.7 mg/kg, respectively. Phenolic compounds determined for the first time in rose hip oil totalled up to 783.55 μg/kg, with a predominant presence of p-coumaric acid methyl ester. Antiradical activity of the oils reached up to 3.00 mM/kg TEAC. The acid, peroxide and p-anisidine values as well as iron and copper contents indicated good quality of the oils. Relatively high protection against oxidative stress in the oils seemed to be a result of their high antioxidant capacity and the level of unsaturation of fatty acids.

  7. 'Fractional heating' differential scanning calorimetry: a tool to study energetics and kinetics of solid-state reactions in photoactive systems with distributed parameters

    NASA Astrophysics Data System (ADS)

    Sworakowski, Juliusz; Nešpůrek, Stanislav

    1998-11-01

    The technique of differential scanning calorimetry (DSC), used in measurements of thermal effects accompanying solid-state chemical reactions, can be regarded as a thermally stimulated method. Model calculations demonstrate the applicability of the DSC technique in determining parameters controlling the kinetics of solid-state reactions. In particular, it has been shown that the fractional heating technique can be successfully used to analyse DSC curves in case of distributions of kinetic parameters. The method was employed to obtain information about the parameters controlling a thermally driven reaction following UV illumination of photoactive 1-methyl-2,4,4,6-tetraphenyl-1,4-dihydropyridine. Two peaks on DSC curves were distinguished, probably corresponding to different processes associated with reactions responsible for the bleaching of the coloured material. The activation energy and the pre-exponential factor of at least one of them were determined.

  8. Cure kinetics of epoxy matrix resin by differential scanning calorimetry

    NASA Technical Reports Server (NTRS)

    Cizmecioglu, M.; Gupta, A.

    1982-01-01

    A study was made on the cure kinetics of an epoxy neat-resin (Narmco 5208) using Differential Scanning Calorimetry (DSC). Two interrelated analytical methods were applied to dynamic DSC data for evaluating the kinetic parameters, such as activation energy, E, the order of reaction, n, and the total heat of polymerization (or crosslinking), delta H sub t. The first method was proposed by Ellerstein (1968), and uses a thorough differential-integral analysis of a single DSC curve to evaluate the kinetic parameters. The second method was proposed by Kissinger (1957), and uses multiple DSC curves obtained at various heating rates to evaluate E regardless of n. Kinetic analysis of Narmco 5208 epoxy resin showed that the reaction order, n, is substantially affected by the rate of heating; i.e., n is approximately 2 at slow scan rates but is reduced to 1.5 at higher scan rates. The activation energy, E, is not affected by the scan rate, and the average value of E is 25.6 + or - 1.8 kcal/mole.

  9. Perfusion calorimetry in the characterization of solvates forming isomorphic desolvates.

    PubMed

    Baronsky, Julia; Preu, Martina; Traeubel, Michael; Urbanetz, Nora Anne

    2011-09-18

    In this study, the potential of perfusion calorimetry in the characterization of solvates forming isomorphic desolvates was investigated. Perfusion calorimetry was used to expose different hydrates forming isomorphic desolvates (emodepside hydrates II-IV, erythromycin A dihydrate and spirapril hydrochloride monohydrate) to stepwise increasing relative vapour pressures (RVP) of water and methanol, respectively, while measuring thermal activity. Furthermore, the suitability of perfusion calorimetry to distinguish the transformation of a desolvate into an isomorphic solvate from the adsorption of solvent molecules to crystal surfaces as well as from solvate formation that is accompanied by structural rearrangement was investigated. Changes in the samples were confirmed using FT-Raman and FT-IR spectroscopy. Perfusion calorimetry indicates the transformation of a desolvate into an isomorphic solvate by a substantial exothermic, peak-shaped heat flow curve at low RVP which reflects the rapid incorporation of solvent molecules by the desolvate to fill the structural voids in the lattice. In contrast, adsorption of solvent molecules to crystal surfaces is associated with distinctly smaller heat changes whereas solvate formation accompanied by structural changes is characterized by an elongated heat flow. Hence, perfusion calorimetry is a valuable tool in the characterization of solvates forming isomorphic desolvates which represents a new field of application for the method.

  10. Studies of human mutation rates

    SciTech Connect

    Neel, J.V.

    1990-01-01

    November 1989, marked the beginning of a new three-year cycle of DOE grant support, in connection with which the program underwent a major reorganization. This document presents the progress on the three objectives of the present program which are: to isolate by the technique of two-dimensional polyacrylamide gel electrophoresis (2-D PAGE), proteins of special interest because of the relative mutability of the corresponding gene, establish the identity of the protein, and, for selected proteins, move to a characterization of the corresponding gene; to develop a more efficient approach, based on 2-D PAGE, for the detection of variants in DNA, with special reference to the identification of mutations in the parents of the individual whose DNA is being examined; and, to continue an effective interface with the genetic studies on the children of atomic bomb survivors in Japan, with reference to both the planning and implementation of new studies at the molecular level.

  11. Studies of human mutation rates

    SciTech Connect

    Neel, J.V.

    1991-07-15

    The three objectives of the program are: To isolate by the technique of two-dimensional polyacrylamide gel electrophoresis (2-D PAGE), proteins of special interest because of the relative mutability of the corresponding gene, establish the identity of the protein, and, for selected proteins, move to a characterization of the corresponding gene; To develop a more efficient approach, based on 2-D PAGE, for the detection of variants in DNA, with special reference to the identification of a variant in a child not present in either parent of the child (i.e., a mutation); and, To continue an effective interface with the genetic studies on the children of atomic bomb survivors in Japan, with reference to both the planning and implementation of new studies at the molecular level. For administrative purposes, the program is subdivided into four sections, each under the direction of one of the four co-PIs; the progress during the past year will be summarized in accordance with this sectional structure. 1 tab.

  12. Pressure perturbation calorimetry of unfolded proteins.

    PubMed

    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.

  13. Analysis of the interactions between human serum albumin/amphiphilic penicillin in different aqueous media: an isothermal titration calorimetry and dynamic light scattering study

    NASA Astrophysics Data System (ADS)

    Barbosa, Silvia; Taboada, Pablo; Mosquera, Victor

    2005-04-01

    The complexation process of the amphiphilic penicillins sodium cloxacillin and sodium dicloxacillin with the protein human serum albumin (HSA) in aqueous buffered solutions of pH 4.5 and 7.4 at 25 °C was investigated through isothermal titration calorimetry (ITC) and dynamic light scattering. ITC experiments were carried out in the very dilute regime and showed that although hydrophobic interactions are the leading forces for complexation, electrostatic interactions also play an important role. The possibility of the formation of hydrogen bonds is also deduced from experimental data. The thermodynamic quantities of the binding mechanism, i.e, the enthalpy, ΔHITCi, entropy, ΔSITCi, Gibbs energy, ΔGITCi, binding constant, KITCi and the number of binding sites, ni, were obtained. The binding was saturable and is characterised by Langmuir adsorption isotherms. From ITC data and following a theoretical model, the number of bound and free penicillin molecules was calculated. From Scatchard plots, KITCi and ni were obtained and compared with those from ITC data. The interaction potential between the HSA-penicillin complexes and their stability were determined at pH 7.4 from the dependence of the diffusion coefficients on protein concentration by application of the DLVO colloidal stability theory. The results indicate decreasing stability of the colloidal dispersion of the drug-protein complexes with increase in the concentration of added drug.

  14. Mechanochemical effect in the iron(III) spin crossover complex [Fe(3-MeO-salenEt2]PF6 as studied by heat capacity calorimetry.

    PubMed

    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.

  15. Differential Binding Models for Direct and Reverse Isothermal Titration Calorimetry.

    PubMed

    Herrera, Isaac; Winnik, Mitchell A

    2016-03-10

    Isothermal titration calorimetry (ITC) is a technique to measure the stoichiometry and thermodynamics from binding experiments. Identifying an appropriate mathematical model to evaluate titration curves of receptors with multiple sites is challenging, particularly when the stoichiometry or binding mechanism is not available. In a recent theoretical study, we presented a differential binding model (DBM) to study calorimetry titrations independently of the interaction among the binding sites (Herrera, I.; Winnik, M. A. J. Phys. Chem. B 2013, 117, 8659-8672). Here, we build upon our DBM and show its practical application to evaluate calorimetry titrations of receptors with multiple sites independently of the titration direction. Specifically, we present a set of ordinary differential equations (ODEs) with the general form d[S]/dV that can be integrated numerically to calculate the equilibrium concentrations of free and bound species S at every injection step and, subsequently, to evaluate the volume-normalized heat signal (δQ(V) = δq/dV) of direct and reverse calorimetry titrations. Additionally, we identify factors that influence the shape of the titration curve and can be used to optimize the initial concentrations of titrant and analyte. We demonstrate the flexibility of our updated DBM by applying these differentials and a global regression analysis to direct and reverse calorimetric titrations of gadolinium ions with multidentate ligands of increasing denticity, namely, diglycolic acid (DGA), citric acid (CIT), and nitrilotriacetic acid (NTA), and use statistical tests to validate the stoichiometries for the metal-ligand pairs studied.

  16. What does calorimetry and thermodynamics of living cells tell us?

    PubMed

    Maskow, Thomas; Paufler, Sven

    2015-04-01

    This article presents and compares several thermodynamic methods for the quantitative interpretation of data from calorimetric measurements. Heat generation and absorption are universal features of microbial growth and product formation as well as of cell cultures from animals, plants and insects. The heat production rate reflects metabolic changes in real time and is measurable on-line. The detection limit of commercially available calorimetric instruments can be low enough to measure the heat of 100,000 aerobically growing bacteria or of 100 myocardial cells. Heat can be monitored in reaction vessels ranging from a few nanoliters up to many cubic meters. Most important the heat flux measurement does not interfere with the biological process under investigation. The practical advantages of calorimetry include the waiver of labeling and reactants. It is further possible to assemble the thermal transducer in a protected way that reduces aging and thereby signal drifts. Calorimetry works with optically opaque solutions. All of these advantages make calorimetry an interesting method for many applications in medicine, environmental sciences, ecology, biochemistry and biotechnology, just to mention a few. However, in many cases the heat signal is merely used to monitor biological processes but only rarely to quantitatively interpret the data. Therefore, a significant proportion of the information potential of calorimetry remains unutilized. To fill this information gap and to motivate the reader using the full information potential of calorimetry, various methods for quantitative data interpretations are presented, evaluated and compared with each other. Possible errors of interpretation and limitations of quantitative data analysis are also discussed.

  17. Fragility of Ionic Liquids Measured by Flash Differential Scanning Calorimetry

    NASA Astrophysics Data System (ADS)

    Tao, Ran; Gurung, Eshan; Quitevis, Edward L.; Simon, Sindee L.

    Ionic liquids are a class of materials that possess attractive properties. They generally have low rates of crystallization due to their bulky and asymmetrical ion structure, and are often considered as good glass-forming materials. In this work, a series of imidazolium-based ionic liquids with varying functionalities from aliphatic to aromatic groups and a fixed anion are characterized using fast scanning differential scanning calorimetry. The limiting fictive temperature Tf', which is equivalent to the glass transition temperature Tg, is measured on heating as a function of cooling rate using Flash differential scanning calorimetry. Different calculation methods are employed and compared for the determination of Tf'. The dynamic fragility is obtained for the series of ionic liquids, and using this data along with a compilation of data from the literature reveals the relationship between molecular structure and fragility for ionic liquids.

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

    SciTech Connect

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

    2014-10-27

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

  19. A comparative study of surface energies and water adsorption on Ce-bastnäsite, La-bastnäsite, and calcite via density functional theory and water adsorption calorimetry.

    PubMed

    Goverapet Srinivasan, Sriram; Shivaramaiah, Radha; Kent, Paul R C; Stack, Andrew G; Riman, Richard; Anderko, Andre; Navrotsky, Alexandra; Bryantsev, Vyacheslav S

    2017-03-06

    Bastnäsite, a fluoro-carbonate mineral, is the single largest mineral source of light rare earth elements (REE), La, Ce and Nd. Enhancing the efficiency of separation of the mineral from gangue through froth flotation is the first step towards meeting an ever increasing demand for REE. To design and evaluate collector molecules that selectively bind to bastnäsite, a fundamental understanding of the structure and surface properties of bastnäsite is essential. In our earlier work (J. Phys. Chem. C, 2016, 120, 16767), we carried out an extensive study of the structure, surface stability and water adsorption energies of La-bastnäsite. In this work, we make a comparative study of the surface properties of Ce-bastnäsite, La-bastnäsite, and calcite using a combination of density functional theory (DFT) and water adsorption calorimetry. Spin polarized DFT+U calculations show that the exchange interaction between the electrons in Ce 4f orbitals is negligible and that these orbitals do not participate in bonding with the oxygen atom of the adsorbed water molecule. In agreement with calorimetry, DFT calculations predict larger surface energies and stronger water adsorption energies on Ce-bastnäsite than on La-bastnäsite. The order of stabilities for stoichiometric surfaces is as follows: [101[combining macron]0] > [101[combining macron]1] > [101[combining macron]2] > [0001] > [112[combining macron]2] > [101[combining macron]4] and the most favorable adsorption sites for water molecules are the same as for La-bastnäsite. In agreement with water adsorption calorimetry, at low coverage water molecules are strongly stabilized via coordination to the surface Ce(3+) ions, whereas at higher coverage they are adsorbed less strongly via hydrogen bonding interaction with the surface anions. Due to similar water adsorption energies on bastnäsite [101[combining macron]1] and calcite [101[combining macron]4] surfaces, the design of collector molecules that selectively bind to

  20. Ice premelting during differential scanning calorimetry

    PubMed Central

    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

  1. Energy dispersive x-ray diffractometry as a tool alternative to differential scanning calorimetry for investigating polymer phase transitions

    NASA Astrophysics Data System (ADS)

    Rossi-Albertini, V.; Isopo, A.; Caminiti, R.; Tentolini, U.

    2002-02-01

    Recently, a technique based on energy dispersive x-ray diffraction has been proposed to follow the polymer phase transitions. However, the potentialities of this method were not clear, as well as the experimental conditions in which it is more convenient than differential scanning calorimetry, generally used for the same purpose. In the present letter, the answer to this question is provided. It is shown that the two methods are complementary, rather than equivalent, the heating rate being the relevant parameter to establish which is preferable. The demonstration of this statement is given through the observation of the complex thermal properties of a reference sample studied in both ways at progressively lower heating rates. The connection between such unusual application of x-ray diffraction and the differential scanning calorimetry is discussed in terms of the two possible definitions of entropy.

  2. 75 FR 80866 - Credit Rating Standardization Study

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-23

    ... From the Federal Register Online via the Government Publishing Office SECURITIES AND EXCHANGE COMMISSION Credit Rating Standardization Study AGENCY: Securities and Exchange Commission. ACTION: Request for comment. SUMMARY: The Securities and Exchange Commission is requesting public comment to...

  3. Applications of high pressure differential scanning calorimetry to aviation fuel thermal stability research

    NASA Technical Reports Server (NTRS)

    Neveu, M. C.; Stocker, D. P.

    1985-01-01

    High pressure differential scanning calorimetry (DSC) was studied as an alternate method for performing high temperature fuel thermal stability research. The DSC was used to measure the heat of reaction versus temperature of a fuel sample heated at a programmed rate in an oxygen pressurized cell. Pure hydrocarbons and model fuels were studied using typical DSC operating conditions of 600 psig of oxygen and a temperature range from ambient to 500 C. The DSC oxidation onset temperature was determined and was used to rate the fuels on thermal stability. Kinetic rate constants were determined for the global initial oxidation reaction. Fuel deposit formation is measured, and the high temperature volatility of some tetralin deposits is studied by thermogravimetric analysis. Gas chromatography and mass spectrometry are used to study the chemical composition of some DSC stressed fuels.

  4. Differential scanning calorimetry of plant cell walls

    SciTech Connect

    Lin, Liangshiou; Varner, J.E. ); Yuen, H.K. )

    1991-03-15

    High-sensitivity differential scanning calorimetry has been used to study the phase transition of cell wall preparations of the elongating and mature regions of soybean hypocotyls and of celery epidermis and collenchyma strands. A step-like transition believed to be glass transition was observed in walls isolated from the elongating region of soybean hypocotyls at 52.9C. Addition of 1 mM CaCl{sub 2} to the cell wall preparation increased the transition temperature to 60.8C and greatly reduced the transition magnitude. In walls from the mature region, the transition was small and occurred at a higher temperature (60.1C). Addition of calcium to the mature region cell wall had little effect on the transition. Based on the known interactions between calcium and pectin, the authors propose that calcium affects the glass transition by binding to the polygalacturonate backbone of wall pectin, resulting in a more rigid wall with a smaller transition at a higher temperature. The mature region either has more calcium in the wall or has more methyl-esterified pectin, making it less responsive to added calcium.

  5. Extruded scintillator for the calorimetry applications

    SciTech Connect

    Dyshkant, A.; Rykalin, V.; Pla-Dalmau, A.; Beznosko, D.; /SUNY, Stony Brook

    2006-08-01

    An extrusion line has been installed and successfully operated at FNAL (Fermi National Accelerator Laboratory) in collaboration with NICADD (Northern Illinois Center for Accelerator and Detector Development). This new Facility will serve to further develop and improve extruded plastic scintillator. Recently progress has been made in producing co-extruded plastic scintillator, thus increasing the potential HEP applications of this Facility. The current R&D work with extruded and co-extruded plastic scintillator for a potential ALICE upgrade, the ILC calorimetry program and the MINERvA experiment show the attractiveness of the chosen strategy for future experiments and calorimetry. We extensively discuss extruded and co-extruded plastic scintillator in calorimetry in synergy with new Solid State Photomultipliers. The characteristics of extruded and co-extruded plastic scintillator will be presented here as well as results with non-traditional photo read-out.

  6. 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.

  7. The Electromagnetic Calorimetry of the PANDA Detector at FAIR

    NASA Astrophysics Data System (ADS)

    Novotny, R. W.; PANDA Collaboration

    2012-12-01

    The PANDA collaboration at FAIR, Germany, will focus on undiscovered charm-meson states and glueballs in antiproton annihilations to study QCD phenomena in the non-perturbative regime. For fixed target experiments at the storage ring HESR a 4π-detector for tracking, particle ID and calorimetry is under development and construction to operate at high annihilation rates up to 20 MHz. The electromagnetic calorimeters are composed of a target spectrometer (EMC) based on PbWO4 crystals and a shashlyk-type sampling calorimeter at the most forward region. The EMC, comprising more than 15,000 crystals, is operated at a temperature of -25°C and read-out via large-area avalanche photo-diodes or vacuum phototriodes/tetrodes. The photo sensor signals are continuously digitized by sampling ADCs. More than 50% of the high quality PWO-II crystals are delivered and tested. The excellent performance with respect to energy, time and position information was determined over a shower energy range from 10 MeV up to 15 GeV by operating several prototype detectors. In addition, the concept of stimulated recovery has been investigated to recover radiation damage on- and off-line during the calorimeter operation. Besides the overall concept of the target spectrometer the response function of the shashlyk spectrometer down to photon energies even below 100 MeV is presented.

  8. Characterization of membrane protein interactions by isothermal titration calorimetry.

    PubMed

    Situ, Alan J; Schmidt, Thomas; Mazumder, Parichita; Ulmer, Tobias S

    2014-10-23

    Understanding the structure, folding, and interaction of membrane proteins requires experimental tools to quantify the association of transmembrane (TM) helices. Here, we introduce isothermal titration calorimetry (ITC) to measure integrin αIIbβ3 TM complex affinity, to study the consequences of helix-helix preorientation in lipid bilayers, and to examine protein-induced lipid reorganization. Phospholipid bicelles served as membrane mimics. The association of αIIbβ3 proceeded with a free energy change of -4.61±0.04kcal/mol at bicelle conditions where the sampling of random helix-helix orientations leads to complex formation. At bicelle conditions that approach a true bilayer structure in effect, an entropy saving of >1kcal/mol was obtained from helix-helix preorientation. The magnitudes of enthalpy and entropy changes increased distinctly with bicelle dimensions, indicating long-range changes in bicelle lipid properties upon αIIbβ3 TM association. NMR spectroscopy confirmed ITC affinity measurements and revealed αIIbβ3 association and dissociation rates of 4500±100s(-1) and 2.1±0.1s(-1), respectively. Thus, ITC is able to provide comprehensive insight into the interaction of membrane proteins.

  9. Advances in temperature derivative control and calorimetry

    SciTech Connect

    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.}

  10. Chip calorimetry for fast and reliable evaluation of bactericidal and bacteriostatic treatments of biofilms.

    PubMed

    Buchholz, F; Wolf, A; Lerchner, J; Mertens, F; Harms, H; Maskow, T

    2010-01-01

    Chip calorimetry is introduced as a new monitoring tool that provides real-time information about the physiological state of biofilms. Its potential for use for the study of the effects of antibiotics and other biocides was tested. Established Pseudomonas putida biofilms were exposed to substances known to cause toxicity by different mechanisms and to provoke different responses of defense and resistance. The effects of these compounds on heat production rates were monitored and compared with the effects of these compounds on the numbers of CFU and intracellular ATP contents. The real-time monitoring potential of chip calorimetry was successfully demonstrated by using as examples the fast-acting poisons formaldehyde and 2,4-dinitrophenol (DNP). A dosage of antibiotics initially increased the heat production rate. This was discussed as being the effect of energy-dependent resistance mechanisms (e.g., export and/or transformation of the antibiotic). The subsequent reduction in the heat production rate was attributed to the loss of activity and the death of the biofilm bacteria. The shapes of the death curves were in agreement with the assumed variation in the levels of exposure of cells within the multilayer biofilms. The new monitoring tool provides fast, quantitative, and mechanistic insights into the acute and chronic effects of a compound on biofilm activity while requiring only minute quantities of the biocide.

  11. Reading and listening to music increase resting energy expenditure during an indirect calorimetry test.

    PubMed

    Snell, Blaire; Fullmer, Susan; Eggett, Dennis L

    2014-12-01

    Indirect calorimetry is often done early in the morning in a fasting state, with the subject unshowered and abstained from caffeine or other stimulants. Subjects often fall asleep, resulting in measurement of a sleeping metabolic rate rather than a resting metabolic rate. The objective of this study was to determine whether listening to self-selected relaxing music or reading an electronic device or magazine affects resting energy expenditure (REE) during measurement in healthy adults. A randomized trial comparing three different conditions (ie, resting, reading, and listening to music) was performed. Sixty-five subjects (36 female and 29 male) were used in final data analysis. Inclusion criteria included healthy subjects between the ages of 18 and 50 years with a stable weight. Exclusion criteria included pregnant or lactating women or use of medications known to affect metabolism. Results showed that reading either a magazine or an electronic device significantly increased REE by 102.7 kcal/day when compared with resting (P<0.0001); however, there was no difference in REE between the electronic device and magazine. Listening to self-selected relaxing music increased REE by 27.6 kcal/day compared with rest (P=0.0072). Based on our results, we recommend subjects refrain from reading a magazine or electronic device during an indirect calorimetry test. Whether or not the smaller difference found while listening to music is practically significant would be a decision for the indirect calorimetry test administrator.

  12. 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…

  13. Final Technical Report CMS fast optical calorimetry

    SciTech Connect

    Winn, David R.

    2012-07-12

    This is the final report of CMS FAST OPTICAL CALORIMETRY, a grant to Fairfield University for development, construction, installation and operation of the forward calorimeter on CMS, and for upgrades of the forward and endcap calorimeters for higher luminosity and radiation damage amelioration.

  14. 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)

  15. Determination of Heats of Fusion: Using Differential Scanning Calorimetry for the AP Chemistry Courses.

    ERIC Educational Resources Information Center

    Temme, Susan M.

    1995-01-01

    Describes an exercise designed to be used in an Advanced Placement (AP) chemistry course to accompany the study of thermodynamics. Uses Differential Scanning Calorimetry in teaching the concepts of thermochemistry and thermodynamics. (JRH)

  16. Effect of Body Position on Energy Expenditure of Preterm Infants as Determined by Simultaneous Direct and Indirect Calorimetry.

    PubMed

    Bell, Edward F; Johnson, Karen J; Dove, Edwin L

    2017-04-01

    Background Indirect calorimetry is the standard method for estimating energy expenditure in clinical research. Few studies have evaluated indirect calorimetry in infants by comparing it with simultaneous direct calorimetry. Our purpose was (1) to compare the energy expenditure of preterm infants determined by these two methods, direct calorimetry and indirect calorimetry; and (2) to examine the effect of body position, supine or prone, on energy expenditure. Study Design We measured energy expenditure by simultaneous direct (heat loss by gradient-layer calorimeter corrected for heat storage) and indirect calorimetry (whole-body oxygen consumption and carbon dioxide production) in 15 growing preterm infants during two consecutive interfeeding intervals, once in the supine position and once in the prone position. Results The mean energy expenditure for all measurements in both positions did not differ significantly by the method used: 2.82 (standard deviation [SD] 0.42) kcal/kg/h by direct calorimetry and 2.78 (SD 0.48) kcal/kg/h by indirect calorimetry. The energy expenditure was significantly lower, by 10%, in the prone than in the supine position, whether examined by direct calorimetry (2.67 vs. 2.97 kcal/kg/h, p < 0.001) or indirect calorimetry (2.64 vs. 2.92 kcal/kg/h, p = 0.017). Conclusion Direct calorimetry and indirect calorimetry gave similar estimates of energy expenditure. Energy expenditure was 10% lower in the prone position than in the supine position.

  17. Isothermal Titration Calorimetry: Assisted Crystallization of RNA-Ligand Complexes.

    PubMed

    Da Veiga, Cyrielle; Mezher, Joelle; Dumas, Philippe; Ennifar, Eric

    2016-01-01

    The success rate of nucleic acids/ligands co-crystallization can be significantly improved by performing preliminary biophysical analyses. Among suitable biophysical approaches, isothermal titration calorimetry (ITC) is certainly a method of choice. ITC can be used in a wide range of experimental conditions to monitor in real time the formation of the RNA- or DNA-ligand complex, with the advantage of providing in addition the complete binding profile of the interaction. Following the ITC experiment, the complex is ready to be concentrated for crystallization trials. This chapter describes a detailed experimental protocol for using ITC as a tool for monitoring RNA/small molecule binding, followed by co-crystallization.

  18. Low-temperature phase transitions in [Cd(DMSO)6](BF4)2 studied by differential scanning calorimetry, X-ray single crystal diffraction and infrared absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Szostak, Elżbieta; Migdał-Mikuli, Anna; Bernard, Paweł

    2015-07-01

    The differential scanning calorimetry (DSC) measurements made for [Cd(DMSO)6](BF4)2, in the temperature range of 113-298 K revealed existence of two low-temperature solid-solid phase transitions: phase Cr 3 ↔ phase Cr 2 at Tc2 c = 218 K and phase Cr 2 ↔ phase Cr 1 at Tc1 c = 246 K. X-ray single crystal diffraction studies of [Cd(DMSO)6](BF4)2 have shown that these transitions are related to a crystal symmetry reduction from an orthorhombic crystallographic system (Fdd2, No. 43) to a monoclinic one (Cc, No. 9). The [Cd(DMSO)6](BF4)2 compound undergoes also series of reversible high temperature phase transitions but they are not a subject of this work and will be presented in our next paper. The characteristic changes of the FT-FIR, FT-MIR and FT-RS spectra of [Cd(DMSO)6](BF4)2 at the phase transitions' temperatures confirmed that phase transitions phase Cr 3 ↔ phase Cr 2 ↔ phase Cr 1 are related to the crystal structure change. It was also found that the reorientation of the BF4- anions and DMSO ligands freezes below 218 K.

  19. Heat killing of bacterial spores analyzed by differential scanning calorimetry.

    PubMed

    Belliveau, B H; Beaman, T C; Pankratz, H S; Gerhardt, P

    1992-07-01

    Thermograms of the exosporium-lacking dormant spores of Bacillus megaterium ATCC 33729, obtained by differential scanning calorimetry, showed three major irreversible endothermic transitions with peaks at 56, 100, and 114 degrees C and a major irreversible exothermic transition with a peak at 119 degrees C. The 114 degrees C transition was identified with coat proteins, and the 56 degrees C transition was identified with heat inactivation. Thermograms of the germinated spores and vegetative cells were much alike, including an endothermic transition attributable to DNA. The ascending part of the main endothermic 100 degrees C transition in the dormant-spore thermograms corresponded to a first-order reaction and was correlated with spore death; i.e., greater than 99.9% of the spores were killed when the transition peak was reached. The maximum death rate of the dormant spores during calorimetry, calculated from separately measured D and z values, occurred at temperatures above the 73 degrees C onset of thermal denaturation and was equivalent to the maximum inactivation rate calculated for the critical target. Most of the spore killing occurred before the release of most of the dipicolinic acid and other intraprotoplast materials. The exothermic 119 degrees C transition was a consequence of the endothermic 100 degrees C transition and probably represented the aggregation of intraprotoplast spore components. Taken together with prior evidence, the results suggest that a crucial protein is the rate-limiting primary target in the heat killing of dormant bacterial spores.

  20. Time-resolved x-ray diffraction and calorimetric studies at low scan rates

    PubMed Central

    Tenchov, Boris G.; Yao, Haruhiko; Hatta, Ichiro

    1989-01-01

    The phase transitions in fully hydrated dipalmitoylphosphatidylcholine (DPPC) and DPPC/water/ethanol phases have been studied by lowangle time-resolved x-ray diffraction under conditions similar to those employed in calorimetry (scan rates 0.05-0.5°C/min and uniform temperature throughout the samples). This approach provides more adequate characterization of the equilibrium transition pathways and allows for close correlations between structural and thermodynamic data. No coexistence of the rippled gel (Pβ') and liquid-crystalline (Lα) phases was found in the main transition of DPPC; rather, a loss of correlation in the lamellar structure, observed as broadening of the lamellar reflections, takes place in a narrow temperature range of ∼100 mK at the transition midpoint. Formation of a long-living metastable phase, denoted by Pβ'(mst), differing from the initial Pβ' was observed in cooling direction by both x-ray diffraction and calorimetry. No direct conversion of Pβ'(mst) into Pβ' occurs for over 24 h but only by way of the phase sequence Pβ'(mst) → Lβ' → Pβ'. According to differential scanning calorimetry (DSC), the enthalpy of the Pβ'(mst)-Lα transition is by ∼5% lower than that of the Pβ'-Lα transition. The effects of ethanol (Rowe, E. S. 1983. Biochemistry. 22:3299-3305; Simon, S. A., and T. J. McIntosh. 1984. Biochim. Biophys. Acta 773:169-172) on the mechanism and reversibility of the DPPC main transition were clearly visualized. At ethanol concentrations inducing formation of interdigitated gel phase, the main transition proceeds through a coexistence of the initial and final phases over a finite temperature range. During the subtransition in DPPC recorded at scan rate 0.3°C/min, a smooth monotonic increase of the lamellar spacing from its subgel (Lc) to its gel (Lβ') phase value takes place. The width of the lamellar reflections remains unchanged during this transformation. This provides grounds to propose a

  1. The use of uniaxial accelerometry for the assessment of physical-activity-related energy expenditure: a validation study against whole-body indirect calorimetry.

    PubMed

    Kumahara, Hideaki; Schutz, Yves; Ayabe, Makoto; Yoshioka, Mayumi; Yoshitake, Yutaka; Shindo, Munehiro; Ishii, Kojiro; Tanaka, Hiroaki

    2004-02-01

    Assessing the total energy expenditure (TEE) and the levels of physical activity in free-living conditions with non-invasive techniques remains a challenge. The purpose of the present study was to investigate the accuracy of a new uniaxial accelerometer for assessing TEE and physical-activity-related energy expenditure (PAEE) over a 24 h period in a respiratory chamber, and to establish activity levels based on the accelerometry ranges corresponding to the operationally defined metabolic equivalent (MET) categories. In study 1, measurement of the 24 h energy expenditure of seventy-nine Japanese subjects (40 (SD 12) years old) was performed in a large respiratory chamber. During the measurements, the subjects wore a uniaxial accelerometer (Lifecorder; Suzuken Co. Ltd, Nagoya, Japan) on their belt. Two moderate walking exercises of 30 min each were performed on a horizontal treadmill. In study 2, ten male subjects walked at six different speeds and ran at three different speeds on a treadmill for 4 min, with the same accelerometer. O2 consumption was measured during the last minute of each stage and was expressed in MET. The measured TEE was 8447 (SD 1337) kJ/d. The accelerometer significantly underestimated TEE and PAEE (91.9 (SD 5.4) and 92.7 (SD 17.8) % chamber value respectively); however, there was a significant correlation between the two values (r 0.928 and 0.564 respectively; P<0.001). There was a strong correlation between the activity levels and the measured MET while walking (r(2) 0.93; P<0.001). Although TEE and PAEE were systematically underestimated during the 24 h period, the accelerometer assessed energy expenditure well during both the exercise period and the non-structured activities. Individual calibration factors may help to improve the accuracy of TEE estimation, but the average calibration factor for the group is probably sufficient for epidemiological research. This method is also important for assessing the diurnal profile of physical activity.

  2. Probing the combined effect of flunitrazepam and lidocaine on the stability and organization of bilayer lipid membranes. A differential scanning calorimetry and dynamic light scattering study.

    PubMed

    Caruso, Benjamín; Sánchez, Julieta M; García, Daniel A; de Paula, Eneida; Perillo, María A

    2013-07-01

    Combined effects of flunitrazepam (FNZ) and lidocaine (LDC) were studied on the thermotropic equilibrium of dipalmitoyl phosphatidylcholine (dpPC) bilayers. This adds a thermodynamic dimension to previously reported geometric analysis in the erythrocyte model. LDC decreased the enthalpy and temperature for dpPC pre- and main-transitions (ΔHp, ΔHm, Tp, Tm) and decreased the cooperativity of the main-transition (ΔT(1/2,m)). FNZ decreased ΔHm and, at least up to 59 μM, also decreased ΔHp. In conjunction with LDC, FNZ induced a recovery of ∆T(1/2,m) control values and increased ΔHm even above the control level. The deconvolution of the main-transition peak at high LDC concentrations revealed three components possibly represented by: a self-segregated fraction of pure dpPC, a dpPC-LDC mixture and a phase with a lipid structure of intermediate stability associated with LDC self-aggregation within the lipid phase. Some LDC effects on thermodynamic parameters were reverted at proper LDC/FNZ molar ratios, suggesting that FNZ restricts the maximal availability of the LDC partitioned into the lipid phase. Thus, beyond its complexity, the lipid-LDC mixture can be rationalized as an equilibrium of coexisting phases which gains homogeneity in the presence of FNZ. This work stresses the relevance of nonspecific drug-membrane binding on LDC-FNZ pharmacological interactions and would have pharmaceutical applications in liposomal multidrug-delivery.

  3. 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.

  4. Analysis of RNA folding and ligand binding by conventional and high-throughput calorimetry.

    PubMed

    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.

  5. Lack of Seasonal Differences in Basal Metabolic Rate in Humans: A Cross-Sectional Study.

    PubMed

    Anthanont, Pimjai; Levine, James A; McCrady-Spitzer, Shelly K; Jensen, Michael D

    2017-01-01

    Some studies indicate that basal metabolic rate is greater in winter than in the summer, suggesting a role for brown fat in human thermogenesis. We examined whether there are clinically meaningful differences in basal metabolic rate under thermoneutral conditions between winter and summer months in inhabitants of Rochester, Minnesota. We collated data from 220 research volunteers studied in the winter (December 1 - February 28) and 214 volunteers studied in the summer (June 1 - August 31), 1995-2012. Basal metabolic rate was measured by indirect calorimetry and body composition by dual-energy X-ray absorptiometry. The effect of season on basal metabolic rate was tested using multivariate regression analysis with basal metabolic rate as the dependent variable and fat-free mass, fat mass, age, sex, and season as the independent variables. The groups were comparable with respect to age, body mass index, fat mass, and fat-free mass. There was no significant difference in basal metabolic rate between winter and summer groups (1 667±322 vs. 1 669±330 kcal/day). Both winter and summer basal metabolic rates were strongly predicted by fat-free mass (Pearson's r=0.75 and r=0.77, respectively, p <0.0001). Using multiple linear regression analysis, basal metabolic rate was significantly, independently predicted by fat-free mass, fat mass, age, and sex, but not season. We conclude that the lack of seasonal variation of thermoneutral basal metabolic rate between winter and summer suggests that modern, Western populations do not engage thermogenically detectable brown fat activity during periods of living in a cold climate.

  6. Direct calorimetry of free-moving eels with manipulated thyroid status

    NASA Astrophysics Data System (ADS)

    van Ginneken, Vincent; Ballieux, Bart; Antonissen, Erik; van der Linden, Rob; Gluvers, Ab; van den Thillart, Guido

    2007-02-01

    In birds and mammals, the thyroid gland secretes the iodothyronine hormones of which tetraiodothyronine (T4) is less active than triiodothyronine (T3). The action of T3 and T4 is calorigenic and is involved in the control of metabolic rate. Across all vertebrates, thyroid hormones also play a major role in differentiation, development and growth. Although the fish thyroidal system has been researched extensively, its role in thermogenesis is unclear. In this study, we measured overall heat production to an accuracy of 0.1 mW by direct calorimetry in a free-moving European eel ( Anguilla anguilla L.) with different thyroid status. Hyperthyroidism was induced by injection of T3 and T4, and hypothyroidism was induced with phenylthiourea. The results show for the first time at the organismal level, using direct calorimetry, that neither overall heat production nor overall oxygen consumption in eels is affected by hyperthyroidism. Therefore, we conclude that the thermogenic metabolism-stimulating effect of thyroid hormones (TH) is not present with a cold-blooded fish species like the European eel. This supports the concept that TH does not stimulate thermogenesis in poikilothermic species.

  7. Recent developments for the analysis of data obtained from isothermal calorimetry.

    PubMed

    O'Neill, M A A

    2005-06-01

    Isothermal calorimetry is rapidly becoming an indispensable tool for the quantitative determination of a variety of kinetic and thermodynamic parameters for a wide range of systems. In particular calorimetry is finding increased application to the investigation of stability and incompatibility of pharmaceutical materials. In order to draw meaningful conclusions and to predict behaviour in related systems it is necessary to have the means to calculate accurately parameters such as the rate constant and enthalpy. To this end several groups have been developing equations which describe calorimetric output in these terms. This paper will briefly outline some of these equations and discuss some of the limitations that currently exist in their application. A particular emphasis is placed on the recent developments relating to the application of these equations to flow calorimetric data. The main application of these equations is usually found in the pharmaceutical industry. Pharmaceutical formulations are usually extremely complex mixtures consisting of many different excipients as well as the active drug. Because of these large numbers of ingredients it is often observed that multiple chemical and physical process occur over the lifetime of the study. This complexity is then reflected in the calorimetric data rendering the application of the simple equations useless. Dealing with this complexity is a major issue amongst the calorimetric community and some of the recent advances in this field are also discussed.

  8. Calorimetry, activity, and micro-FTIR analysis of CO chemisorption, titration, and oxidation on supported Pt

    NASA Technical Reports Server (NTRS)

    Sermon, Paul A.; Self, Valerie A.; Vong, Mariana S. W.; Wurie, Alpha T.

    1990-01-01

    The value of in situ analysis on CO chemisorption, titration and oxidation over supported Pt catalysts using calorimetry, catalytic and micro-FTIR methods is illustrated using silica- and titania-supported samples. Isothermal CO-O and O2-CO titrations have not been widely used on metal surfaces and may be complicated if some oxide supports are reduced by CO titrant. However, they can illuminate the kinetics of CO oxidation on metal/oxide catalysts since during such titrations all O and CO coverages are scanned as a function of time. There are clear advantages in following the rates of the catalyzed CO oxidation via calorimetry and gc-ms simultaneously. At lower temperatures the evidence they provide is complementary. CO oxidation and its catalysis of CO oxidation have been extensively studied with hysteresis and oscillations apparent, and the present results suggest the benefits of a combined approach. Silica support porosity may be important in defining activity-temperature hysteresis. FTIR microspectroscopy reveals the chemical heterogeneity of the catalytic surfaces used; it is interesting that the evidence with regard to the dominant CO surface species and their reactivities with regard to surface oxygen for present oxide-supported Pt are different from those seen on graphite-supported Pt.

  9. Phase transitions of the system Ag sub 2 HgI sub 4 -Cu sub 2 HgI sub 4 at normal and high pressure studied by differential scanning calorimetry

    SciTech Connect

    Friesel, M.; Baranowski, B.; Lunden, A. )

    1990-02-08

    Differential scanning calorimetry has been applied for studying the system Ag{sub 2}HgI{sub 4}-Cu{sub 2}HgI{sub 4} at both normal and high pressure. It is confirmed that there is a miscibility gap in the ordered phase and that the order-disorder phase transition has a eutectoid point at 307 K and 42.7 mol % Cu{sub 2}HgI{sub 4} at normal pressure, which is about 30 K higher than expected from a calculation for ideal eutectic behavior. The order-disorder transition is of first-order character over the whole composition range, confirming the interpretation by Suchow and ruling out the suggestion by Jaffray that it should be of second-order character in the middle part of the range. The transition enthalpy is equal to 7.3 {plus minus} 0.2 kJ/mol for the eutectoid composition. The phase diagram of the eutectoid composition was determined for pressures up to 0.72 GPa, and the temperature of the order-disorder transition increased from 307 to about 325 K, The correlation was not linear over the whole pressure range, but an average dT/dP slope of 25 K/GPa is in good agreement with the 24 K/GPa calculated by means of van Laar,s formula. The transition enthalpy (kJ/mol) decreased linearly with increasing pressure with d{Delta}H/dp = -4.0 kJ/(mol GPa). A calculation from simple additive rule gives instead d{Delta}H/dp = -1.5 kJ/(mol GPa).

  10. Fragment-Based Screening for Enzyme Inhibitors Using Calorimetry.

    PubMed

    Recht, Michael I; Nienaber, Vicki; Torres, Francisco E

    2016-01-01

    Isothermal titration calorimetry (ITC) provides a sensitive and accurate means by which to study the thermodynamics of binding reactions. In addition, it enables label-free measurement of enzymatic reactions. The advent of extremely sensitive microcalorimeters have made it increasingly valuable as a tool for hit validation and characterization, but its use in primary screening is hampered by requiring large quantities of reagents and long measurement times. Nanocalorimeters can overcome these limitations of conventional ITC, particularly for screening libraries of 500-1000 compounds such as those encountered in fragment-based lead discovery. This chapter describes how nanocalorimetry and conventional microcalorimetry can be used to screen compound libraries for enzyme inhibitors.

  11. Uniformity requirements in CMS hadron calorimetry

    SciTech Connect

    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.

  12. Calorimetry exchange program. Annual report, 1988

    SciTech Connect

    Lyons, J.E.

    1988-12-31

    The goals of the Calorimetry Sample Program are: 1. Discuss measurement differences, 2. Review and improve analytical measurements and methods, 3. Discuss new measurement capabilities, 4. Provide data to DOE on measurement capabilities to evaluate shipper- receiver differences, 5. Provide characterized or standard materials as necessary for exchange participants, 6. Provide a measurement control program for plutonium analysis. A sample of PuO{sub 2} powder is available at each participating site for NDA measurement, including either or both calorimetry and high-resolution gamma-ray spectroscopy, the elements which are typically combined to provide a calorimetric assay of plutonium. The facilities measure the sample as frequently and to the level of precision which they desire, and then submit the data to the Exchange for analysis. Statistical tests are used to evaluate the data and to determine if there are significant differences from accepted values for the exchange or from data previously reported by that facility. Data included in this report is a compilation of all exchange data received in 1988. Since a large number of data points were recorded, a change was made to the analysis method to account for the uncertainty in the accepted values.

  13. Energetics of methanol and formic acid oxidation on Pt(111): Mechanistic insights from adsorption calorimetry

    NASA Astrophysics Data System (ADS)

    Silbaugh, Trent L.; Karp, Eric M.; Campbell, Charles T.

    2016-08-01

    The catalytic and electrocatalytic oxidation and reforming of methanol and formic acid have received intense interest due to potential use in direct fuel cells and as prototype models for understanding electrocatalysis. Consequently, the reaction energy diagram (energies of all the adsorbed intermediates and activation energies of all the elementary steps) have been estimated for these reactions on Pt(111) by density functional theory (DFT) in several studies. However, no experimental measurement of these energy diagrams have been reported, nor is there a consensus on the mechanisms. Here, we use energies of key intermediates on Pt(111) from single crystal adsorption calorimetry (SCAC) and temperature programmed desorption (TPD) to build a combined energy diagram for these reactions. It suggests a new pathway involving monodentate formate as a key intermediate, with bidentate formate only being a spectator species that slows the rate. This helps reconcile conflicting proposed mechanisms.

  14. Online particle detection with Neural Networks based on topological calorimetry information

    NASA Astrophysics Data System (ADS)

    Ciodaro, T.; Deva, D.; de Seixas, J. M.; Damazio, D.

    2012-06-01

    This paper presents the latest results from the Ringer algorithm, which is based on artificial neural networks for the electron identification at the online filtering system of the ATLAS particle detector, in the context of the LHC experiment at CERN. The algorithm performs topological feature extraction using the ATLAS calorimetry information (energy measurements). The extracted information is presented to a neural network classifier. Studies showed that the Ringer algorithm achieves high detection efficiency, while keeping the false alarm rate low. Optimizations, guided by detailed analysis, reduced the algorithm execution time by 59%. Also, the total memory necessary to store the Ringer algorithm information represents less than 6.2 percent of the total filtering system amount.

  15. Multi-slope warm-up calorimetry of Integrated Dewar-Detector Assemblies

    NASA Astrophysics Data System (ADS)

    Veprik, Alexander; Shlomovich, Baruch; Tuito, Avi

    2015-05-01

    Boil-off isothermal calorimetry of Integrated Dewar-Detector Assemblies (IDDA) is a routine part of acceptance testing. In this traditional approach, the cryogenic liquid coolant (typically LN2) is allowed to naturally boil off from the Dewar well to the atmosphere. The parasitic heat load is then evaluated as the product of the latent heat of vaporization and the "last drop" boil-off rate monitored usually by a mass flow meter. An inherent limitation of this technique is that it is applicable only at the fixed boiling temperature of the chosen liquid coolant, for example, 77K for LN2. There is a need, therefore, to use other (often exotic) cryogenic liquids when calorimetry is needed at temperatures other than 77K. A further drawback is related to the transitional nature of last drop boiling, which manifests itself in development of enlarged bubbles, explosions and geysering. This results in an uneven flow rate and also affects the natural temperature gradient along the cold finger. Additionally, mass flow meters are known to have limited measurement accuracy. The above considerations especially hold true for advanced High Operational Temperature IDDAs, typically featuring short cold fingers and working at 150K and above. In this work, we adapt the well-known technique of dual-slope calorimetry and show how accurate calorimetry may be performed by precooling the IDDA and comparing the warm-up slopes of the thermal transient processes under different trial added heat loads. Because of the simplicity, accuracy and ability to perform calorimetry literally at any temperature of interest, this technique shows good potential for replacing traditional boil-off calorimetry.

  16. Isothermal Titration Calorimetry of Chiral Polymeric Nanoparticles.

    PubMed

    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.

  17. Isothermal Titration Calorimetry to Characterize Enzymatic Reactions.

    PubMed

    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.

  18. Study of Guaranteed Student Loan Default Rates.

    ERIC Educational Resources Information Center

    Lee, John B.

    Data on Guaranteed Student Loan (GSL) program defaults for 1965 to early 1981 are presented, as are characteristics of GSL lenders. Default rate data are provided by state agency, year of birth of loan recipient, last academic year, year of last loan, elapsed time between last loan and current status, institutional type and control, and…

  19. Differential Scanning Calorimetry Techniques: Applications in Biology and Nanoscience

    PubMed Central

    Gill, Pooria; Moghadam, Tahereh Tohidi; Ranjbar, Bijan

    2010-01-01

    This paper reviews the best-known differential scanning calorimetries (DSCs), such as conventional DSC, microelectromechanical systems-DSC, infrared-heated DSC, modulated-temperature DSC, gas flow-modulated DSC, parallel-nano DSC, pressure perturbation calorimetry, self-reference DSC, and high-performance DSC. Also, we describe here the most extensive applications of DSC in biology and nanoscience. PMID:21119929

  20. Differential scanning calorimetry techniques: applications in biology and nanoscience.

    PubMed

    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.

  1. The physics of compensating calorimetry and the new CALOR89 code system

    SciTech Connect

    Gabriel, T.A.; Brau, J.E.; Bishop, B.L.

    1989-03-01

    Much of the understanding of the physics of calorimetry has come from the use of excellent radiation transport codes. A new understanding of compensating calorimetry was introduced four years ago following detailed studies with a new CALOR system. Now, the CALOR system has again been revised to reflect a better comprehension of high energy nuclear collisions by incorporating a modified high energy fragmentation model from FLUKA87. This revision will allow for the accurate analysis of calorimeters at energies of 100's of GeV. Presented in this paper is a discussion of compensating calorimetry, the new CALOR system, the revisions to HETC, and recently generated calorimeter related data on modes of energy deposition and secondary neutron production (E < 50 MeV) in infinite iron and uranium blocks. 38 refs., 5 figs., 5 tabs.

  2. Isothermal titration calorimetry of ion-coupled membrane transporters.

    PubMed

    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.

  3. Tin clusters that do not melt: Calorimetry measurements up to 650 K

    NASA Astrophysics Data System (ADS)

    Breaux, Gary A.; Neal, Colleen M.; Cao, Baopeng; Jarrold, Martin F.

    2005-02-01

    Recent theoretical studies [K. Joshi, D. G. Kanhere, and S. A. Blundell, Phys. Rev. B 67, 235413 (2003)] predict that Sn20 melts at around 1200K . We have performed calorimetry measurements on unsupported Sn18+ , Sn19+ , Sn20+ , and Sn21+ in an effort to test this prediction. We find that these tin clusters disappear well below their predicted melting temperature due to dissociation. Calorimetry measurements performed up to around 650K show some small features (which may be due to localized structural changes) but no clear melting transitions. Hence, tin clusters in this size regime do not melt—they sublime.

  4. Small pad RPCs as detector for high granularity digital hadron calorimetry

    NASA Astrophysics Data System (ADS)

    Ammosov, V.; Gapienko, V.; Ivanilov, A.; Sefkow, F.; Semak, A.; Sviridov, Yu.; Usenko, E.; Zaets, V.

    2004-11-01

    Requirements for sampling hadron calorimetry with gaseous active medium and digital read-out for a future linear e+e--collider (FLC) are formulated. Monogap glass Resistive Plate Chamber (RPC) prototypes equipped with 1cm2 read-out pads and operated in saturated avalanche and streamer modes are studied as a possible detector for digital hadron calorimetry. Operating characteristics of the prototypes such as induced charges, efficiencies and fired pad multiplicities are measured for different gas mixtures, gas gap widths and anode thicknesses, electronics thresholds, beam incident angle and intensity. Choice of RPC working performance is outlined.

  5. Melting by temperature-modulated calorimetry

    SciTech Connect

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

    1997-09-01

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

  6. Current status of tritium calorimetry at TLK

    SciTech Connect

    Buekki-Deme, A.; Alecu, C.G.; Kloppe, B.; Bornschein, B.

    2015-03-15

    Inside a tritium facility, calorimetry is an important analytical method as it is the only reference method for accountancy (it is based on the measurement of the heat generated by the radioactive decay). Presently, at Tritium Laboratory Karlsruhe (TLK), 4 calorimeters are in operation, one of isothermal type and three of inertial guidance control type (IGC). The volume of the calorimeters varies between 0.5 and 20.6 liters. About two years ago we started an extensive work to improve our calorimeters with regard to reliability and precision. We were forced to upgrade 3 of our 4 calorimeters due to the outdated interfaces and software. This work involved creating new LabView programs driving the devices, re-tuning control loops and replacing obsolete hardware components. In this paper we give a review on the current performance of our calorimeters, comparing it to recently available devices from the market and in the literature. We also show some ideas for a next generation calorimeter based on experiences with our IGC calorimeters and other devices reported in the literature. (authors)

  7. Measuring the Kinetics of Molecular Association by Isothermal Titration Calorimetry.

    PubMed

    Vander Meulen, Kirk A; Horowitz, Scott; Trievel, Raymond C; Butcher, Samuel E

    2016-01-01

    The real-time power response inherent in an isothermal titration calorimetry (ITC) experiment provides an opportunity to directly analyze association kinetics, which, together with the conventional measurement of thermodynamic quantities, can provide an incredibly rich description of molecular binding in a single experiment. Here, we detail our application of this method, in which interactions occurring with relaxation times ranging from slightly below the instrument response time constant (12.5 s in this case) to as large as 600 s can be fully detailed in terms of both the thermodynamics and kinetics. In a binding titration scenario, in the most general case an injection can reveal an association rate constant (kon). Under more restrictive conditions, the instrument time constant-corrected power decay following each injection is simply an exponential decay described by a composite rate constant (kobs), from which both kon and the dissociation rate constant (koff) can be extracted. The data also support the viability of this exponential approach, for kon only, for a slightly larger set of conditions. Using a bimolecular RNA folding model and a protein-ligand interaction, we demonstrate and have internally validated this approach to experiment design, data processing, and error analysis. An updated guide to thermodynamic and kinetic regimes accessible by ITC is provided.

  8. Study Stings KIPP on Attrition Rates

    ERIC Educational Resources Information Center

    Zehr, Mary Ann

    2011-01-01

    Knowledge Is Power Program (KIPP) charter middle schools enroll a significantly higher proportion of African-American students than the local school districts they draw from, but 40 percent of the black males they enroll leave between grades 6 and 8, says a new nationwide study by researchers at Western Michigan University. With 99 charter schools…

  9. NEUTRON-ENHANCED CALORIMETRY FOR HADRONS (NECH): FINAL REPORT

    SciTech Connect

    Andrew Stroud, Lee Sawyer

    2012-08-31

    We present the results of a project to apply scintillator technology recently developed at Louisiana Tech University to hadronic calorimetry. In particular, we developed a prototype calorimeter module incorporating scintillator embedded with metal oxide nanoparticles as the active layers. These metal oxide nanoparticles of gadolinium oxide, have high cross-sections for interactions with slow neutrons. As a part fo this research project, we have developed a novel method for producing plastic scintillators with metal oxide nanoparticles evenly distributed through the plastic without aggregation.We will test the performance of the calorimeter module in test beam and with a neutron source, in order to measure the response to the neutron component of hadronic showers. We will supplement our detector prototyping activities with detailed studies of the effect of neutron component on the resolution of hadronic energy measurements, particular in the next generation of particle flow calorimeters.

  10. Isothermal titration calorimetry of membrane proteins - progress and challenges.

    PubMed

    Rajarathnam, Krishna; Rösgen, Jörg

    2014-01-01

    Integral membrane proteins, including G protein-coupled receptors (GPCR) and ion channels, mediate diverse biological functions that are crucial to all aspects of life. The knowledge of the molecular mechanisms, and in particular, the thermodynamic basis of the binding interactions of the extracellular ligands and intracellular effector proteins is essential to understand the workings of these remarkable nanomachines. In this review, we describe how isothermal titration calorimetry (ITC) can be effectively used to gain valuable insights into the thermodynamic signatures (enthalpy, entropy, affinity, and stoichiometry), which would be most useful for drug discovery studies, considering that more than 30% of the current drugs target membrane proteins. This article is part of a Special Issue entitled: Structural and biophysical characterisation of membrane protein-ligand binding.

  11. Crystallization of isotactic polypropylene from mesomorphic phase: a constant heating rate study

    NASA Astrophysics Data System (ADS)

    Asakawa, H.; Nishida, K.; Matsuba, G.; Kanaya, T.; Ogawa, H.

    2011-01-01

    We have studied crystallization behaviour of isotactic polypropylene (iPP) from mesomorphic phase in structural point of view. Time-resolved wide-angle X-ray diffraction (WAXD) measurements during a heating process have been performed using a synchrotron radiation (SR) X-ray beam line at SPring-8, Japan. The heating process was so programmed to reproduce a thermal trace of differential scanning calorimetry (DSC) with a constant heating rate (10 °C/min) in order to compare the structural change with thermal behaviour. SR-WAXD sensitively detected the crystallization behaviour and we have obtained fractions of alpha-crystal, mesomorphic phase and amorphous phase as a function of temperature by analysing the data. The results showed that the crystallization from mesomorphic phase proceeds in between 60 and 120 °C (meso-alpha transition). During this process, the crystallization from amorphous hardly takes place. The crystalline fraction shows almost constant in between 120 and 140 °C meanwhile, the mesomorphic fraction still decreases above 120 °C. The crystalline fraction starts to decrease above 140 °C and the most extensively decreases at around 165 °C (melting point). We have also determined the energy level of the mesomorphic phase (meta-stable state) relative to that of alpha-crystal (stable state), considering the balance among the fractions of alpha-crystal, mesomorphic phase and amorphous.

  12. The study of human mutation rates

    SciTech Connect

    Neel, J.V.

    1992-01-01

    We will describe recent developments regarding the question of induced mutations in the survivors of the atomic bombings of Hiroshima and Nagasaki. As part of that work we, describe some developments with respect to the Amerindian blood samples collected under DoE sponsorship between 1964 and 1982. Then developments regarding the application of two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) to the study of genetic variation and mutation affecting protein characteristics. In particular, we will report on the identification and isolation of genes of especial interest as reflected in the behavior of the proteins which they encode.

  13. Photoacoustic calorimetry study of ligand photorelease from the Ru(II)bis(2,2‧-bipyridine)(6,6‧-dimethyl-2,2‧-bipyridine) complex in aqueous solution

    NASA Astrophysics Data System (ADS)

    Word, Tarah A.; Whittington, Christi L.; Karolak, Aleksandra; Kemp, M. Trent; Woodcock, H. Lee; van der Vaart, Arjan; Larsen, Randy W.

    2015-01-01

    The thermodynamics of ligand photorelease from Ru(II)bis(2,2‧-bipyridine)(6,6‧-dimethyl-2,2‧-bipyridine) ([Ru(bpy)2(dmbpy)]2+) complex in aqueous solution have been examined using photoacoustic calorimetry (PAC). Photolysis of the [Ru(bpy)2(dmbpy)]2+ complex with a ∼5 ns laser pulse (FWHM) results in enthalpy changes of 42 ± 4 kcal mol-1, with a corresponding volume change of 6 ± 1 mL mol-1. Density functional theory calculations also demonstrate that the positive enthalpy values arise from N σ-donation to the Ru ion. It is noted that the LUMO-Ligand Field gap fails to track with photoaquation quantum yield.

  14. Luminosity limits for liquid argon calorimetry

    NASA Astrophysics Data System (ADS)

    J, Rutherfoord; B, Walker R.

    2012-12-01

    We have irradiated liquid argon ionization chambers with betas using high-activity Strontium-90 sources. The radiation environment is comparable to that in the liquid argon calorimeters which are part of the ATLAS detector installed at CERN's Large Hadron Collider. We measure the ionization current over a wide range of applied potential for two different source activities and for three different chamber gaps. These studies provide operating experience at exceptionally high ionization rates. We can operate these chambers either in the normal mode or in the space-charge limited regime and thereby determine the transition point between the two. From the transition point we indirectly extract the positive argon ion mobility.

  15. 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.

  16. Evaluation of three flame retardant (FR) grey cotton blend nonwoven fabrics using micro-scale combustion calorimetry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Unbleached (grey or greige) cotton nonwoven (NW) fabrics (with 12.5% polypropylene scrim) were treated with three phosphate-nitrogen based FR formulations and evaluated with micro-scale combustion calorimetry (MCC). Heat release rate (HRR), Peak heat rate (PHRR), temperature at peak heat release ra...

  17. 2007 Wholesale Power Rate Case Initial Proposal : Wholesale Power Rate Development Study.

    SciTech Connect

    United States. Bonneville Power Administration.

    2007-11-01

    The Wholesale Power Rate Development Study (WPRDS) calculates BPA proposed rates based on information either developed in the WPRDS or supplied by the other studies that comprise the BPA rate proposal. All of these studies, and accompanying documentation, provide the details of computations and assumptions. In general, information about loads and resources is provided by the Load Resource Study (LRS), WP-07-E-BPA-01, and the LRS Documentation, WP-07-E-BPA-01A. Revenue requirements information, as well as the Planned Net Revenues for Risk (PNNR), is provided in the Revenue Requirement Study, WP-07-E-BPA-02, and its accompanying Revenue Requirement Study Documentation, WP-07-E-BPA-02A and WP-07-E-BPA-02B. The Market Price Forecast Study (MPFS), WP-07-E-BPA-03, and the MPFS Documentation, WP-07-E-BPA-03A, provide the WPRDS with information regarding seasonal and diurnal differentiation of energy rates, as well information regarding monthly market prices for Demand Rates. In addition, this study provides information for the pricing of unbundled power products. The Risk Analysis Study, WP-07-E-BPA-04, and the Risk Analysis Study Documentation, WP-07-E-BPA-04A, provide short-term balancing purchases as well as secondary energy sales and revenue. The Section 7(b)(2) Rate Test Study, WP-07-E-BPA-06, and the Section 7(b)(2) Rate Test Study Documentation, WP-07-E-BPA-06A, implement Section 7(b)(2) of the Northwest Power Act to ensure that BPA preference customers firm power rates applied to their general requirements are no higher than rates calculated using specific assumptions in the Northwest Power Act.

  18. In-situ probing of metallic glass formation and crystallization upon heating and cooling via fast differential scanning calorimetry

    NASA Astrophysics Data System (ADS)

    Pogatscher, S.; Uggowitzer, P. J.; Löffler, J. F.

    2014-06-01

    The crystallization of small-scale Au-based metallic glass samples was investigated by fast differential scanning calorimetry. Rapid cooling and heating makes possible in-situ probing of glass formation from the supercooled liquid state or direct transition from the glassy state to the equilibrium liquid and, thereby, the determination of a critical cooling (Φc ˜ 600 Ks-1) and heating rate (Φh ˜ 6 × 103 Ks-1) for crystallization. Crystallization kinetics was studied in the whole supercooled liquid region by linear heating and isothermal calorimetry. We show that the temperature dependence of crystal growth is reflected in a "Kissinger plot" for Au49Ag5.5Pd2.3Cu26.9Si16.3 and compares well with a model for crystal growth in a glassy system. Linear heating and isothermal measurements after heating the glass show that its crystallization is always growth-controlled up to its temperature of melting. In contrast, for a low degree of direct undercooling from the equilibrium liquid isothermal crystallization is nucleation-controlled, whereas it is again growth-controlled at large undercooling. The overall crystallization behavior of the metallic glass is presented in a complete time-temperature-transformation map on cooling and, so far not accessible, on heating after various cooling procedures.

  19. Simultaneous Differential Scanning Calorimetry and Thermogravimetric Analysis of Portland Cement as a Function of Age

    NASA Astrophysics Data System (ADS)

    Trník, Anton; Scheinherrová, Lenka; Kulovaná, Tereza; Černý, Robert

    2016-01-01

    We study the hydration and pozzolanic reactions of an ordinary Portland cement as a function of age, using the differential scanning calorimetry and thermogravimetry. The measurements are done for 2 days, 7 days, 28 days, 90 days, 180 days, and 360 days cured samples in order to monitor the rate of hydration. The investigation is performed in the temperature range from 25° C to 1000° C with a heating rate 5° C {\\cdot} min^{-1} in an argon atmosphere. The temperature, enthalpy, and mass change during the decomposition of calcium silicate hydrate gels, ettringite, portlandite, vaterite, and calcite are determined, and the changes in the portlandite amount are estimated in dependence on the time of hydration. We found out that the temperature and enthalpy of liberation of physically bound water, C-S-H gels and ettringite decomposition (all occurring from 50° C to 250° C) and Portlandite decomposition (420° C to 530° C) decrease with hydration time of studied samples. On the other hand, vaterite and calcite decomposition (530° C to 850° C) the temperature varies and the enthalpy increases with hydration time of samples.

  20. 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)

  1. Isoquinoline alkaloids and their binding with DNA: calorimetry and thermal analysis applications.

    PubMed

    Bhadra, Kakali; Kumar, Gopinatha Suresh

    2010-11-01

    Alkaloids are a group of natural products with unmatched chemical diversity and biological relevance forming potential quality pools in drug screening. The molecular aspects of their interaction with many cellular macromolecules like DNA, RNA and proteins are being currently investigated in order to evolve the structure activity relationship. Isoquinolines constitute an important group of alkaloids. They have extensive utility in cancer therapy and a large volume of data is now emerging in the literature on their mode, mechanism and specificity of binding to DNA. Thermodynamic characterization of the binding of these alkaloids to DNA may offer key insights into the molecular aspects that drive complex formation and these data can provide valuable information about the balance of driving forces. Various thermal techniques have been conveniently used for this purpose and modern calorimetric instrumentation provides direct and quick estimation of thermodynamic parameters. Thermal melting studies and calorimetric techniques like isothermal titration calorimetry and differential scanning calorimetry have further advanced the field by providing authentic, reliable and sensitive data on various aspects of temperature dependent structural analysis of the interaction. In this review we present the application of various thermal techniques, viz. isothermal titration calorimetry, differential scanning calorimetry and optical melting studies in the characterization of drug-DNA interactions with particular emphasis on isoquinoline alkaloid-DNA interaction.

  2. Direct absorbed dose to water determination based on water calorimetry in scanning proton beam delivery

    SciTech Connect

    Sarfehnia, A.; Clasie, B.; Chung, E.; Lu, H. M.; Flanz, J.; Cascio, E.; Engelsman, M.; Paganetti, H.; Seuntjens, J.

    2010-07-15

    Purpose: The aim of this manuscript is to describe the direct measurement of absolute absorbed dose to water in a scanned proton radiotherapy beam using a water calorimeter primary standard. Methods: The McGill water calorimeter, which has been validated in photon and electron beams as well as in HDR {sup 192}Ir brachytherapy, was used to measure the absorbed dose to water in double scattering and scanning proton irradiations. The measurements were made at the Massachusetts General Hospital proton radiotherapy facility. The correction factors in water calorimetry were numerically calculated and various parameters affecting their magnitude and uncertainty were studied. The absorbed dose to water was compared to that obtained using an Exradin T1 Chamber based on the IAEA TRS-398 protocol. Results: The overall 1-sigma uncertainty on absorbed dose to water amounts to 0.4% and 0.6% in scattered and scanned proton water calorimetry, respectively. This compares to an overall uncertainty of 1.9% for currently accepted IAEA TRS-398 reference absorbed dose measurement protocol. The absorbed dose from water calorimetry agrees with the results from TRS-398 well to within 1-sigma uncertainty. Conclusions: This work demonstrates that a primary absorbed dose standard based on water calorimetry is feasible in scattered and scanned proton beams.

  3. 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).

  4. Study: California Ethnic Groups Seeing Increased Cancer Rates

    ERIC Educational Resources Information Center

    Black Issues in Higher Education, 2005

    2005-01-01

    A statewide study on cancer and ethnicity hints that cancer rates among immigrant groups may be tied to their degree of assimilation into American culture. The study, released by the University of Southern California's Norris Comprehensive Cancer Center, marks the first statewide look at cancer rates among Vietnamese and South Asians and provides…

  5. Torn human rotator cuff tendons have reduced collagen thermal properties on differential scanning calorimetry.

    PubMed

    Chaudhury, Salma; Holland, Christopher; Porter, David; Tirlapur, Uday K; Vollrath, Fritz; Carr, Andrew J

    2011-12-01

    The cause of the high failure rates often observed following rotator cuff tendon repairs, particularly massive tears, is not fully understood. Collagen structural changes have been shown to alter tendon thermal and mechanical properties. This study aimed to form a quantitative rather than qualitative assessment, of whether differences in collagen structure and integrity existed between small biopsies of normal, small, and massive rotator cuff tears using differential scanning calorimetry. Thermal properties were measured for 28 human biopsies taken intra-operatively from normal, small, and massive rotator cuff tendon tears in this powered study. Denaturation temperatures are represented by T(onset) (°C) and T(peak) (°C). The T(onset) is proposed to represent water-amide hydrogen bond breakage and resulting protein backbone mobility. T(peak) reportedly corresponds to the temperature at which the majority of proteins fall out of solution. Denaturation enthalpy (ΔH) should correlate with the amount of triple helical structure that is denatured. Fluorescence and confocal microscopy allowed quantitative validation. Small and massive rotator cuff tears had significantly higher T(onset), T(peak), and ΔH compared to controls. Polarized light microscopy of torn tendons confirmed greater collagen structural disruption compared to controls. These novel findings suggest greater quantifiable collagen structural disruption in rotator cuff tears, compared to controls. This study offers insight into possible mechanisms for the reduced strength of torn tendons and may explain why repaired tendons fail to heal.

  6. The influence of the potassium promoter on the kinetics and thermodynamics of CO adsorption on a bulk iron catalyst applied in Fischer-Tropsch synthesis: a quantitative adsorption calorimetry, temperature-programmed desorption, and surface hydrogenation study.

    PubMed

    Graf, Barbara; Muhler, Martin

    2011-03-07

    The adsorption of carbon monoxide on an either unpromoted or potassium-promoted bulk iron catalyst was investigated at 303 K and 613 K by means of pulse chemisorption, adsorption calorimetry, temperature-programmed desorption and temperature-programmed surface reaction in hydrogen. CO was found to adsorb mainly molecularly in the absence of H(2) at 303 K, whereas the presence of H(2) induced CO dissociation at higher temperatures leading to the formation of CH(4) and H(2)O. The hydrogenation of atomic oxygen chemisorbed on metallic iron was found to occur faster than the hydrogenation of atomically adsorbed carbon. At 613 K CO adsorption occurred only dissociatively followed by recombinative CO(2) formation according to C(ads) + 2O(ads)→ CO(2(g)). The presence of the potassium promoter on the catalyst surface led to an increasing strength of the Fe-C bond both at 303 K and 613 K: the initial differential heat of molecular CO adsorption on the pure iron catalyst at 303 K amounted to 102 kJ mol(-1), whereas it increased to 110 kJ mol(-1) on the potassium-promoted sample, and the initial differential heat of dissociative CO adsorption on the unpromoted iron catalyst at 613 K amounted to 165 kJ mol(-1), which increased to 225 kJ mol(-1) in the presence of potassium. The calorimetric CO adsorption experiments also reveal a change of the energetic distribution of the CO adsorption sites present on the catalyst surface induced by the potassium promoter, which was found to block a fraction of the CO adsorption sites.

  7. Use of scanning calorimetry and microrespiration to determine effects of Bt toxin doses on Pandemis leafroller (Lepidoptera: Tortricidae) metabolism

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Differential scanning calorimetry and microrespiration were used to determine the effects of the biopesticide, Bt toxin, on the metabolism of infected Pandemis leafroller, Pandemis purusana (Kearfott). The metabolic heat rate, CO2 evolution, O2 consumption of 2nd and 3rd instars following a 2 h expo...

  8. Application and use of isothermal calorimetry in pharmaceutical development.

    PubMed

    O'Neill, Michael A A; Gaisford, Simon

    2011-09-30

    There are many steps involved in developing a drug candidate into a formulated medicine and many involve analysis of chemical interaction or physical change. Calorimetry is particularly suited to such analyses as it offers the capacity to observe and quantify both chemical and physical changes in virtually any sample. Differential scanning calorimetry (DSC) is ubiquitous in pharmaceutical development, but the related technique of isothermal calorimetry (IC) is complementary and can be used to investigate a range of processes not amenable to analysis by DSC. Typically, IC is used for longer-term stability indicating or excipient compatibility assays because both the temperature and relative humidity (RH) in the sample ampoule can be controlled. However, instrument design and configuration, such as titration, gas perfusion or ampoule-breaking (solution) calorimetry, allow quantification of more specific values, such as binding enthalpies, heats of solution and quantification of amorphous content. As ever, instrument selection, experiment design and sample preparation are critical to ensuring the relevance of any data recorded. This article reviews the use of isothermal, titration, gas-perfusion and solution calorimetry in the context of pharmaceutical development, with a focus on instrument and experimental design factors, highlighted with examples from the recent literature.

  9. HEAT OF HYDRATION OF SALTSTONE MIXES-MEASUREMENT BY ISOTHERMAL CALORIMETRY

    SciTech Connect

    Harbour, J; Vickie Williams, V; Tommy Edwards, T

    2007-07-02

    This report provides initial results on the measurement of heat of hydration of Saltstone mixes using isothermal calorimetry. The results were obtained using a recently purchased TAM Air Model 3116 Isothermal Conduction Calorimeter. Heat of hydration is an important property of Saltstone mixes. Greater amounts of heat will increase the temperature of the curing mix in the vaults and limit the processing rate. The heat of hydration also reflects the extent of the hydraulic reactions that turn the fluid mixture into a ''stone like'' solid and consequently impacts performance properties such as permeability. Determining which factors control these reactions, as monitored by the heat of hydration, is an important goal of the variability study. Experiments with mixes of portland cement in water demonstrated that the heats measured by this technique over a seven day period match very well with the literature values of (1) seven day heats of hydration using the standard test method for heat of hydration of hydraulic cement, ASTM C 186-05 and (2) heats of hydration measured using isothermal calorimetry. The heats of hydration of portland cement or blast furnace slag in a Modular Caustic Side Solvent Extraction Unit (MCU) simulant revealed that if the cure temperature is maintained at 25 C, the amount of heat released over a seven day period is roughly 62% less than the heat released by portland cement in water. Furthermore, both the blast furnace slag and the portland cement were found to be equivalent in heat production over the seven day period in MCU. This equivalency is due to the activation of the slag by the greater than 1 Molar free hydroxide ion concentration in the simulant. Results using premix (a blend of 10% cement, 45% blast furnace slag, and 45% fly ash) in MCU, Deliquification, Dissolution and Adjustment (DDA) and Salt Waste Processing Facility (SWPF) simulants reveal that the fly ash had not significantly reacted (undergone hydration reactions) after seven

  10. Methodological evaluation of indirect calorimetry data in lean and obese rats.

    PubMed

    Rafecas, I; Esteve, M; Fernández-López, J A; Remesar, X; Alemany, M

    1993-11-01

    1. The applicability of current indirect calorimetry formulae to the study of energy and substrate balances on obese rats has been evaluated. The energy consumption of series of 60-day rats of Wistar, lean and obese Zucker stock were studied by means of direct and indirect calorimetry, and by establishing their energy balance through measurement of food intake and retention. Calorimetric studies encompassed a 24 h period, with gas and heat output measurements every 2 or 5 min, respectively, for direct and indirect calorimetry. 2. The analysis of fat composition (diet, whole rat, and synthesized and oxidized fat) showed only small variations that had only a limited effect on the overall energy equation parameters. 3. A gap in the nitrogen balance, which represents a urinary N excretion lower than the actual protein oxidized, resulted in significant deviations in the estimation of carbohydrate and lipid oxidized when using the equations currently available for indirect calorimetry. 4. Analysis of the amino acid composition of diet and rat protein as well as of the portion actually oxidized, and correcting for the nitrogen gap allowed the establishment of a set of equations that gave better coincidence of the calculated data with the measured substrate balance. 5. The measured heat output of all rats was lower than the estimated values calculated by means of either indirect calorimetry of direct energy balance measurement; the difference corresponded to the energy lost in water evaporation, and was in the range of one-fifth of total energy produced in the three rat stocks. 6. Wistar rats showed a biphasic circadian rhythm of substrate utilization, with alternate lipid synthesis/degradation that reversed that of carbohydrate, concordant with nocturnal feeding habits. Zucker rats did not show this rhythm; obese rats synthesized large amounts of fat during most of the light period, consuming fat at the end of the dark period, which suggests more diurnal feeding habits

  11. Studies of the mortality rate of Culicoides imicola in Morocco.

    PubMed

    Baylis, M; Touti, J; Bouayoune, H; Moudni, L; Taoufiq, B; el Hasnaoui, H

    1998-01-01

    Daily mortality rates of female Culicoides imicola were found for eight sites in Morocco in 1994 and for six sites in 1995. The mortality rates were found by operating Pirbright-type light traps for a number of consecutive nights in late summer or autumn and finding the parous rate assuming a feeding interval of 3 to 5 days. The mortality rates were calculated according to established methods. In Morocco the daily mortality rates were found to vary from about 5% per day (Arbaoua, 1994, 1995 and Sidi Moussa 1995) up to 20-25% per day (Berkane, Marrakech, Tangier). In general, estimates of daily mortality rate were consistent between the two years of study. Among sites, daily mortality rate was significantly correlated with the average night-time minimum wind speed but not mean or maximum night-time wind speeds, or with temperature, humidity or saturation deficit. The observed mortality rates suggest that at Arbaoua, were 1,000 flies to become infected with African horse sickness virus, at least 330 would live long enough to take 3 or more infective blood meals on hosts. At Berkane, the survival rate per 1,000 is less than 10. In general, the pattern observed for daily mortality rate, combined with the relative population sizes of C. imicola in Morocco, agree well with the observed distribution of African horse sickness in the country during the 1989-1991 epizootic.

  12. On the feasibility of water calorimetry with scanned proton radiation.

    PubMed

    Sassowsky, M; Pedroni, E

    2005-11-21

    Water calorimetry is considered to be the most direct primary method to realize the physical quantity gray for absorbed dose to water. The Swiss Federal Office of Metrology and Accreditation (METAS) has routinely operated a water calorimeter as primary standard for photon radiation since 2001. Nowadays, cancer therapy with proton radiation has become increasingly important and is a well established method. In the framework of the ProScan project conducted by the Paul Scherrer Institute (PSI), the spot-scanning technique is prepared for the subsequent application in hospitals, and adjusted to the recent findings of clinical research. In the absence of primary standards for proton radiation, the metrological traceability is assured by calibrating secondary standards in 60Co radiation and correcting with calculated beam quality correction factors. It is internationally recognized that the development of primary standards for proton radiation is highly desirable. In a common project of PSI and METAS, it is investigated whether a modified version of the water calorimeter in operation at METAS is suitable as primary standard for scanned proton radiation. A feasibility study has been conducted to investigate the linear energy transfer (LET) dependence of the heat defect and the influence of the time and space structure of the scanned beam on the homogeneity and stability of the temperature field in the water calorimeter. Simulations are validated against experimental data of the existing calorimeter used with photon radiation and extended to scanned proton radiation.

  13. Mapping glycoside hydrolase substrate subsites by isothermal titration calorimetry

    PubMed Central

    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

  14. Hot biological catalysis: isothermal titration calorimetry to characterize enzymatic reactions.

    PubMed

    Mazzei, Luca; Ciurli, Stefano; Zambelli, Barbara

    2014-04-04

    Isothermal titration calorimetry (ITC) is a well-described technique that measures the heat released or absorbed during a chemical reaction, using it as an intrinsic probe to characterize virtually every chemical process. Nowadays, this technique is extensively applied to determine thermodynamic parameters of biomolecular binding equilibria. In addition, ITC has been demonstrated to be able of directly measuring kinetics and thermodynamic parameters (kcat, KM, ΔH) of enzymatic reactions, even though this application is still underexploited. As heat changes spontaneously occur during enzymatic catalysis, ITC does not require any modification or labeling of the system under analysis and can be performed in solution. Moreover, the method needs little amount of material. These properties make ITC an invaluable, powerful and unique tool to study enzyme kinetics in several applications, such as, for example, drug discovery. In this work an experimental ITC-based method to quantify kinetics and thermodynamics of enzymatic reactions is thoroughly described. This method is applied to determine kcat and KM of the enzymatic hydrolysis of urea by Canavalia ensiformis (jack bean) urease. Calculation of intrinsic molar enthalpy (ΔHint) of the reaction is performed. The values thus obtained are consistent with previous data reported in literature, demonstrating the reliability of the methodology.

  15. Measuring Multivalent Binding Interactions by Isothermal Titration Calorimetry.

    PubMed

    Dam, Tarun K; Talaga, Melanie L; Fan, Ni; Brewer, Curtis F

    2016-01-01

    Multivalent glycoconjugate-protein interactions are central to many important biological processes. Isothermal titration calorimetry (ITC) can potentially reveal the molecular and thermodynamic basis of such interactions. However, calorimetric investigation of multivalency is challenging. Binding of multivalent glycoconjugates to proteins (lectins) often leads to a stoichiometry-dependent precipitation process due to noncovalent cross-linking between the reactants. Precipitation during ITC titration severely affects the quality of the baseline as well as the signals. Hence, the resulting thermodynamic data are not dependable. We have made some modifications to address this problem and successfully studied multivalent glycoconjugate binding to lectins. We have also modified the Hill plot equation to analyze high quality ITC raw data obtained from multivalent binding. As described in this chapter, ITC-driven thermodynamic parameters and Hill plot analysis of ITC raw data can provide valuable information about the molecular mechanism of multivalent lectin-glycoconjugate interactions. The methods described herein revealed (i) the importance of functional valence of multivalent glycoconjugates, (ii) that favorable entropic effects contribute to the enhanced affinities associated with multivalent binding, (iii) that with the progression of lectin binding, the microscopic affinities of the glycan epitopes of a multivalent glycoconjugate decrease (negative cooperativity), (iv) that lectin binding to multivalent glycoconjugates, especially to mucins, involves internal diffusion jumps, (bind and jump) and (v) that scaffolds of glycoconjugates influence their entropy of binding.

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

    NASA Astrophysics Data System (ADS)

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

    2003-01-01

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

  17. Vitreous State Characterization of Pharmaceutical Compounds Degrading upon Melting by Using Fast Scanning Calorimetry.

    PubMed

    Corvis, Yohann; Wurm, Andreas; Schick, Christoph; Espeau, Philippe

    2015-06-04

    Fast scanning calorimetry, a technique mainly devoted to polymer characterization, is applied here for the first time to low molecular mass organic compounds that degrade upon melting, such as ascorbic acid and prednisolone. Due to the fast scan rates upon heating and cooling, the substances can be obtained in the molten state without degradation and then quenched into the glassy state. The hydrated form and the polymorphic Form 1 of prednisolone were investigated. It is shown that once the sesquihydrate dehydrates, a molten product is obtained. Depending on the heating rate, this molten phase may recrystallize or not into Form 1.

  18. [Study of shear rate in modified airlift nitrifying bioreactor].

    PubMed

    Jin, Ren-cun; Zheng, Ping

    2006-06-01

    The characteristics of shear rate in an airlift nitrifying bioreactor and its influencing factors were studied. The results showed that the shear rate was different in different sections of the bioreactor. With inlet gas flowrate at 430 approximately 2700 L x h(-1), the overall shear rate was (0.702 approximately 3.13) x 10(5) s(-1), shear rate in riser was (1.07 approximately 31.3) x 10(5) s(-1) and in gas-liquid separator was (1.12 approximately 25.0) x 10(5) s(-1), respectively. It indicates that the highest shear rates prevailed in the riser part of bioreactor. The operational variables and the bioreactor configurations exerted a significant influence on the shear level of the bioreactor. When inlet gas flowrate was raised from 1300 to 2700 L x h(-1), shear rate in riser and separator ascended first and then descended subsequently. The diameter of draft tube (d) was negatively correlated with shear rate. When the draft tube with diameter of 5.5 cm was installed, the shear rates in riser, separator and overall shear rate were 85.5%, 82.3% and 80.6%, respectively less as compared with that with diameter of 4.0 cm. The number of static mixers (N) was positively correlated with the shear rate. When d was set at 4.0 cm, with N of 10 and 39, the shear rates in riser were 6.14 and 7.97 times higher respectively, than that of conventional bioreactor. The ratio of maximum local shear rate to overall shear rate was 3.68 approximately 7.66, and the homogeneity of the shear field in airlift bioreactors could be improved if d and N were set at 5.5 cm and 10 approximately 13, respectively.

  19. Determination of kinetics and heat of hydrolysis for non-homogenous substrate by isothermal calorimetry.

    PubMed

    Tafoukt, D; Soric, A; Sigoillot, J-C; Ferrasse, J-H

    2017-04-01

    The competitiveness of the second-generation bioethanol by biotechnological process requires an effective and quantitative control of biochemical reactions. In this study, the potential of isothermal calorimetry technique to measure heat and kinetics of a non-homogeneous substrate enzymatic hydrolysis is intended. Using this technique, optimum temperature of the enzymes used for lignocellulosic molecules hydrolysis was determined. Thus, the amount of substrate-to-enzyme ratio was highlighted as an important parameter of the hydrolysis yield. Furthermore, a new enzymes' cocktail efficiency consisting of a mix of cellulases and cellobiose dehydrogenase (CDH) was qualified by this technique. The results showed that this cocktail allowed the production of a high amount of gluconic acid that could improve the attractiveness of these second-generation biofuels. From the set of experiments, the hydrolysis heat of wheat straw was derived and a meaningful value of -32.2 ± 3.2 J g(-1) (gram reducing sugars product) is calculated. Then, isothermal measurements were used to determine kinetic constants of the cellulases and CDH mix on wheat straw. Results showed that this enzyme cocktail has an optimal rate at 45 °C in the range of temperatures tested (40-55 °C).

  20. Study of High Strain Rate Response of Composites

    NASA Technical Reports Server (NTRS)

    Gilat, Amos

    2003-01-01

    The objective of the research was to continue the experimental study of the effect of strain rate on mechanical response (deformation and failure) of epoxy resins and carbon fibers/epoxy matrix composites, and to initiate a study of the effects of temperature by developing an elevated temperature test. The experimental data provide the information needed for NASA scientists for the development of a nonlinear, rate dependent deformation and strength models for composites that can subsequently be used in design. This year effort was directed into testing the epoxy resin. Three types of epoxy resins were tested in tension and shear at various strain rates that ranges from 5 x 10(exp -5), to 1000 per second. Pilot shear experiments were done at high strain rate and an elevated temperature of 80 C. The results show that all, the strain rate, the mode of loading, and temperature significantly affect the response of epoxy.

  1. Air traffic control surveillance accuracy and update rate study

    NASA Technical Reports Server (NTRS)

    Craigie, J. H.; Morrison, D. D.; Zipper, I.

    1973-01-01

    The results of an air traffic control surveillance accuracy and update rate study are presented. The objective of the study was to establish quantitative relationships between the surveillance accuracies, update rates, and the communication load associated with the tactical control of aircraft for conflict resolution. The relationships are established for typical types of aircraft, phases of flight, and types of airspace. Specific cases are analyzed to determine the surveillance accuracies and update rates required to prevent two aircraft from approaching each other too closely.

  2. Characterization of Novel Operation Modes for Secondary Emission Ionization Calorimetry

    NASA Astrophysics Data System (ADS)

    Tiras, Emrah; Dilsiz, Kamuran; Ogul, Hasan; Snyder, Christina; Bilki, Burak; Onel, Yasar; Winn, David

    2017-01-01

    Secondary Emission (SE) Ionization Calorimetry is a novel technique to measure electromagnetic showers in high radiation environments. We have developed new operation modes by modifying the bias of the conventional PMT circuits. Hamamatsu single anode R7761 and multi-anode R5900-00-M16 Photomultiplier Tubes (PMTs) with modified bases are used as SE detector modules in our SE calorimetry prototype. In this detector module, the first dynode is used as the active media as opposed to photocathode. Here, we report the technical design of new modes and characterization measurements for both SE and PMT modes.

  3. An observational study of entrainment rate in deep convection

    DOE PAGES

    Guo, Xiaohao; Lu, Chunsong; Zhao, Tianliang; ...

    2015-09-22

    This study estimates entrainment rate and investigates its relationships with cloud properties in 156 deep convective clouds based on in-situ aircraft observations during the TOGA-COARE (Tropical Ocean Global Atmosphere Coupled Ocean Atmosphere Response Experiment) field campaign over the western Pacific. To the authors’ knowledge, this is the first study on the probability density function of entrainment rate, the relationships between entrainment rate and cloud microphysics, and the effects of dry air sources on the calculated entrainment rate in deep convection from an observational perspective. Results show that the probability density function of entrainment rate can be well fitted by lognormal,more » gamma or Weibull distribution, with coefficients of determination being 0.82, 0.85 and 0.80, respectively. Entrainment tends to reduce temperature, water vapor content and moist static energy in cloud due to evaporative cooling and dilution. Inspection of the relationships between entrainment rate and microphysical properties reveals a negative correlation between volume-mean radius and entrainment rate, suggesting the potential dominance of homogeneous mechanism in the clouds examined. The entrainment rate and environmental water vapor content show similar tendencies of variation with the distance of the assumed environmental air to the cloud edges. Their variation tendencies are non-monotonic due to the relatively short distance between adjacent clouds.« less

  4. An observational study of entrainment rate in deep convection

    SciTech Connect

    Guo, Xiaohao; Lu, Chunsong; Zhao, Tianliang; Zhang, Guang Jun; Liu, Yangang

    2015-09-22

    This study estimates entrainment rate and investigates its relationships with cloud properties in 156 deep convective clouds based on in-situ aircraft observations during the TOGA-COARE (Tropical Ocean Global Atmosphere Coupled Ocean Atmosphere Response Experiment) field campaign over the western Pacific. To the authors’ knowledge, this is the first study on the probability density function of entrainment rate, the relationships between entrainment rate and cloud microphysics, and the effects of dry air sources on the calculated entrainment rate in deep convection from an observational perspective. Results show that the probability density function of entrainment rate can be well fitted by lognormal, gamma or Weibull distribution, with coefficients of determination being 0.82, 0.85 and 0.80, respectively. Entrainment tends to reduce temperature, water vapor content and moist static energy in cloud due to evaporative cooling and dilution. Inspection of the relationships between entrainment rate and microphysical properties reveals a negative correlation between volume-mean radius and entrainment rate, suggesting the potential dominance of homogeneous mechanism in the clouds examined. The entrainment rate and environmental water vapor content show similar tendencies of variation with the distance of the assumed environmental air to the cloud edges. Their variation tendencies are non-monotonic due to the relatively short distance between adjacent clouds.

  5. Evidence analysis library review of best practices for performing indirect calorimetry in healthy and non-critically ill individuals.

    PubMed

    Fullmer, Susan; Benson-Davies, Sue; Earthman, Carrie P; Frankenfield, David C; Gradwell, Erica; Lee, Peggy S P; Piemonte, Tami; Trabulsi, Jillian

    2015-09-01

    When measurement of resting metabolic rate (RMR) by indirect calorimetry is necessary, following evidence-based protocols will ensure the individual has achieved a resting state. The purpose of this project was to update the best practices for measuring RMR by indirect calorimetry in healthy and non-critically ill adults and children found the Evidence Analysis Library of the Academy of Nutrition and Dietetics. The Evidence Analysis process described by the Academy of Nutrition and Dietetics was followed. The Ovid database was searched for papers published between 2003 and 2012 using key words identified by the work group and research consultants, studies used in the previous project were also considered (1980 to 2003), and references were hand searched. The work group worked in pairs to assign papers to specific questions; however, the work group developed evidence summaries, conclusion statements, and recommendations as a group. Only 43 papers were included to answer 21 questions about the best practices to ensure an individual is at rest when measuring RMR in the non-critically ill population. In summary, subjects should be fasted for at least 7 hours and rest for 30 minutes in a thermoneutral, quiet, and dimly lit room in the supine position before the test, without doing any activities, including fidgeting, reading, or listening to music. RMR can be measured at any time of the day as long as resting conditions are met. The duration of the effects of nicotine and caffeine and other stimulants is unknown, but lasts longer than 140 minutes and 240 minutes, respectively. The duration of the effects of various types of exercise on RMR is unknown. Recommendations for achieving steady state, preferred gas-collection devices, and use of respiratory quotient to detect measurement errors are also given. Of the 21 conclusions statements developed in this systemic review, only 5 received a grade I or II. One limitation is the low number of studies available to address the

  6. Revisiting the streptavidin-biotin binding by using an aptamer and displacement isothermal calorimetry titration.

    PubMed

    Kuo, Tai-Chih; Tsai, Ching-Wei; Lee, Peng-Chen; Chen, Wen-Yih

    2015-03-01

    The association constant of a well-known streptavidin-biotin binding has only been inferred from separately measured kinetic parameters. In a single experiment, we obtained Ka 1 × 10(12)  M(-1) by using a streptavidin-binding aptamer and ligand-displacement isothermal titration calorimetry. This study explores the challenges of determining thermodynamic parameters and the derived equilibrium binding affinity of tight ligand-receptor binding.

  7. Elevated Extinction Rates as a Trigger for Diversification Rate Shifts: Early Amniotes as a Case Study

    PubMed Central

    Brocklehurst, Neil; Ruta, Marcello; Müller, Johannes; Fröbisch, Jörg

    2015-01-01

    Tree shape analyses are frequently used to infer the location of shifts in diversification rate within the Tree of Life. Many studies have supported a causal relationship between shifts and temporally coincident events such as the evolution of “key innovations”. However, the evidence for such relationships is circumstantial. We investigated patterns of diversification during the early evolution of Amniota from the Carboniferous to the Triassic, subjecting a new supertree to analyses of tree balance in order to infer the timing and location of diversification shifts. We investigated how uneven origination and extinction rates drive diversification shifts, and use two case studies (herbivory and an aquatic lifestyle) to examine whether shifts tend to be contemporaneous with evolutionary novelties. Shifts within amniotes tend to occur during periods of elevated extinction, with mass extinctions coinciding with numerous and larger shifts. Diversification shifts occurring in clades that possess evolutionary innovations do not coincide temporally with the appearance of those innovations, but are instead deferred to periods of high extinction rate. We suggest such innovations did not cause increases in the rate of cladogenesis, but allowed clades to survive extinction events. We highlight the importance of examining general patterns of diversification before interpreting specific shifts. PMID:26592209

  8. Further studies of human whole-body radiofrequency absorption rates.

    PubMed

    Hill, D A

    1985-01-01

    Further studies of human whole-body radiofrequency (RF) absorption rates were carried out using a TEM-cell exposure system. Experiments were done at one frequency near the grounded resonance frequency (approximately 40 MHz), and at several below-resonance frequencies. Absorption rates are small for the K and H orientations of the body, even when grounded. For the body trunk in an E orientation, the absorption rate of a sitting person is about half of the rate for the same person standing with arms at the sides; the latter in turn is about half the rate for the same subject standing with arms over the head. Two-body interactions cause no increase in absorption rates for grounded people. They do, however, increase the absorption rates for subjects in an E orientation in free space; the largest interaction occurs when one subject is lambda/2 behind the other (as seen by the incident wave). When these results are applied to practical occupational exposure situations, the whole-body specific absorption rate does not exceed the ANSI limit of 0.4 W/kg for exposures permitted by the ANSI standard (C95.1-1982) at frequencies from 7 to 40 MHz.

  9. PREFACE: XIV International Conference on Calorimetry in High Energy Physics

    NASA Astrophysics Data System (ADS)

    Wang, Yifang

    2011-03-01

    (Texas Tech University), Weidong Li (IHEP) 3) Readout techniques - Gerald Eigen (University of Bergen), Zheng Wang (IHEP) 4) Operating calorimeters and calibration - Marat Gataullin (CERN), Francesco Lanni (BNL) 5) Future calorimetry - Tohru Takeshita (Shinshu University), Lei Xia (Argonne National Laboratory) 6) Astrophysics and neutrino calorimetry - Giuliana Fiorillo (INFN), Hiro Tajima (SLAC) List of Participants AKCHURIN, NuralTexas Tech University AN, ZhenghuaIHEP AUFFRAY, EtiennetteCERN BANFI, DaniloUniversità degli Studi di Milano, INFN BASHARINA-FRESHVILLE, AnastasiaUniversity College London BEAUCHEMIN, Pierre-HuguesUniversity of Oxford BENAGLIA, Andrea DavideUniversity of Milano - Bicocca and INFN BIAN, JianminIHEP BIINO, CristinaINFN BILKI, BurakUniversity of Iowa BLAHA, JanLAPP BOUDRY, VincentLLR / CNRS-IN2P3 CAI, XiaoIHEP CAPONE, AntonioPhysics Department University "La Sapienza" and INFN CAVALLARI, FrancescaCERN and INFN Rome CECCHI, ClaudiaUniversity di Perugia e INFN CHANG, JinfanIHEP CHEN, HuchengBrookhaven National Laboratory CHILDERS, TaylorUniversität Heidelberg - Kirchhoff-Institut für Physik DAO, ValerioGeneva University - DPNC DE LA TAILLE, ChristopheIN2P3/OMEGA-LAL DIEMOZ, MarcellaINFN Roma DOTTI, AndreaCERN EIGEN, GeraldUniversity of Bergen EPIFANOV, DenisBudker Institute of Nuclear Physics FAIVRE, JulienLPSC Grenoble France FANG, JianIHEP FANG, ShuangshiIHEP FANTONI, AlessandraINFN - LNF FERRI, FedericoCEA/Saclay Irfu/SPP FERRONI, FernandoSapienza University & INFN Roma FISK, Henry EugeneFermilab GABALDON, CarolinaCERN GARUTTI, ErikaDESY GAUDIO, GabriellaIstituto Nazionale di Fisica Nucleare - Sezione di Pavia GILLBERG, DagCarleton University GIOVANNINI, PaolaMax-Planck-Institut für Physik GLAZOV, AlexanderDESY GRACHOV, OlegUniversity of Kansas HAPPACHER, FabioINFN HE, MiaoIHEP HORI, YasutoUniversity of Tokyo, CNS HU, TaoIHEP HULTH, Per-OlofStockholm University JUN, Soon YungCarnegie Mellon University JURK, StefanISEG Spezialelektronik gmb

  10. Characterization of photomultiplier tubes in a novel operation mode for Secondary Emission Ionization Calorimetry

    NASA Astrophysics Data System (ADS)

    Tiras, E.; Dilsiz, K.; Ogul, H.; Southwick, D.; Bilki, B.; Wetzel, J.; Nachtman, J.; Onel, Y.; Winn, D.

    2016-10-01

    Hamamatsu single anode R7761 and multi-anode R5900-00-M16 Photomultiplier Tubes have been characterized for use in a Secondary Emission (SE) Ionization Calorimetry study. SE Ionization Calorimetry is a novel technique to measure electromagnetic shower particles in extreme radiation environments. The different operation modes used in these tests were developed by modifying the conventional PMT bias circuit. These modifications were simple changes to the arrangement of the voltage dividers of the baseboard circuits. The PMTs with modified bases, referred to as operating in SE mode, are used as an SE detector module in an SE calorimeter prototype, and placed between absorber materials (Fe, Cu, Pb, W, etc.). Here, the technical design of different operation modes, as well as the characterization measurements of both SE modes and the conventional PMT mode are reported.

  11. Preparation of Solid Derivatives by Differential Scanning Calorimetry.

    ERIC Educational Resources Information Center

    Crandall, E. W.; Pennington, Maxine

    1980-01-01

    Describes the preparation of selected aldehydes and ketones, alcohols, amines, phenols, haloalkanes, and tertiaryamines by differential scanning calorimetry. Technique is advantageous because formation of the reaction product occurs and the melting point of the product is obtained on the same sample in a short time with no additional purification…

  12. Superconducting phase in UGe2 by AC calorimetry

    NASA Astrophysics Data System (ADS)

    Taufour, Valentin; Aoki, Dai; Knebel, Georg; Flouquet, Jacques

    2012-12-01

    We report on the detection of the superconducting transition Tsc in the superconducting ferromagnet UGe2 by AC calorimetry under pressure. Our results confirm the small value of the specific heat jump. We suggest that this observation is intrinsic in origin and does not arises from a distribution of Tsc due to pressure gradient or sample defects.

  13. Isothermal Titration Calorimetry Can Provide Critical Thinking Opportunities

    ERIC Educational Resources Information Center

    Moore, Dale E.; Goode, David R.; Seney, Caryn S.; Boatwright, Jennifer M.

    2016-01-01

    College chemistry faculties might not have considered including isothermal titration calorimetry (ITC) in their majors' curriculum because experimental data from this instrumental method are often analyzed via automation (software). However, the software-based data analysis can be replaced with a spreadsheet-based analysis that is readily…

  14. Initial Studies Toward Real-Time Transmission Path Rating

    SciTech Connect

    Singh, Ruchi; Diao, Ruisheng; Cai, Niannian; Huang, Zhenyu; Tuck, Brian; Guo, Xinxin

    2012-07-26

    Demand continues to increase while transmission line construction is being constrained by multiple factors— economic, environmental, and political. Effective and efficient utilization of transmission lines is thus of great importance in an open access environment. Large blocks of power are transferred from areas with inexpensive generation to heavy load demand areas or areas with high generation costs. This results in some transmission paths being loaded closer to their path ratings, which limits further power transfer between areas. Traditionally, rating of important paths was determined off line by assuming the worst-case study scenario; once determined, it could be used for years. With increasing uncertainty arising from rapid growth of renewable energy and smart technologies, path rating studies are needed in near-real time to account for the latest system status and support a reliable and economic power grid. This paper adopts a simplified procedure based on standards of the North American Electric Reliability Corporation (NERC) to determine total transfer capability (TTC) or transfer limit for the purpose of demonstrating the benefits and necessity of real-time path rating. Initial studies are conducted to compute TTC of a two-area test system and a 39-bus test system. Results indicate that path rating can be significantly affected by loading conditions, generator schedules, system topology and other factors.

  15. Cryogenic Laser Calorimetry for Impurity Analysis

    NASA Technical Reports Server (NTRS)

    Swimm, R. T.

    1985-01-01

    The results of a one-year effort to determine the applicability of laser-calorimetric spectroscopy to the study of deep-level impurities in silicon are presented. Critical considerations for impurity analysis by laser-calorimetric spectroscopy are discussed, the design and performance of a cryogenic laser calorimeter is described, and measurements of background absorption in high-purity silicon are presented.

  16. Breakdown Limit Studies in High-Rate Gaseous Detectors

    NASA Technical Reports Server (NTRS)

    Ivaniouchenkov, Yu; Fonte, P.; Peskov, V.; Ramsey, B. D.

    1999-01-01

    We report results from a systematic study of breakdown limits for novel high-rate gaseous detectors: MICROMEGAS, CAT and GEM, together with more conventional devices such as thin-gap parallel-mesh chambers and high-rate wire chambers. It was found that for all these detectors, the maximum achievable pin, before breakdown appears, drops dramatically with incident flux, and is sometimes inversely proportional to it. Further, in the presence of alpha particles, typical of the breakgrounds in high-energy experiments, additional gain drops of 1-2 orders of magnitude were observed for many detectors. It was found that breakdowns at high rates occur through what we have termed an "accumulative" mechanism, which does not seem to have been previously reported in the literature. Results of these studies may help in choosing the optimum detector for given experimental conditions.

  17. Online aging study of a high rate MRPC

    NASA Astrophysics Data System (ADS)

    Wang, Jie; Wang, Yi; Feng, S. Q.; Xie, Bo; Lv, Pengfei; Wang, Fuyue; Guo, Baohong; Han, Dong; Li, Yuanjing

    2016-05-01

    With the constant increase of accelerator luminosity, the rate requirements of MRPC detectors have become very important, and the aging characteristics of the detector have to be studied meticulously. An online aging test system has been set up in our lab, and in this paper the setup of the system is described and the performance stability of a high-rate MRPC studied over a long running time under a high luminosity environment. The high rate MRPC was irradiated by X-rays for 36 days and the accumulated charge density reached 0.1 C/cm2. No obvious performance degradation was observed for the detector. Supported by National Natural Science Foundation of China (11420101004, 11461141011, 11275108), Ministry of Science and Technology (2015CB856905)

  18. Variability in nest survival rates and implications to nesting studies

    USGS Publications Warehouse

    Klett, A.T.; Johnson, D.H.

    1982-01-01

    We used four reasonably large samples (83-213) of Mallard (Anas platyrhynchos) and Blue-winged Teal (A. discors) nests on an interstate highway right-of-way in southcentral North Dakota to evaluate potential biases in hatch-rate estimates. Twelve consecutive, weekly searches for nests were conducted with a cable-chain drag in 1976 and 1977. Nests were revisited at weekly intervals. Four methods were used to estimate hatch rates for the four data sets: the Traditional Method, the Mayfield Method, and two modifications of the Mayfield Method that are sometimes appropriate when daily mortality rates of nests are not constant. Hatch rates and the average age of nests at discovery declined as the interval between searches decreased, suggesting that mortality rates were not constant in our samples. An analysis of variance indicated that daily mortality rates varied with the age of nests in all four samples. Mortality was generally highest during the early laying period, moderately high during the late laying period, and lowest during incubation. We speculate that this relationship of mortality to nest age might be due to the presence of hens at nests or to differences in the vulnerability of nest sites to predation. A modification of the Mayfield Method that accounts for age-related variation in nest mortality was most appropriate for our samples. We suggest methods for conducting nesting studies and estimating nest success for species possessing similar nesting habits.

  19. Injury Rates in Iranian Taekwondo Athletes; a Prospective Study

    PubMed Central

    Ziaee, Vahid; Rahmani, Seyed-Hessam; Rostami, Mohsen

    2010-01-01

    Purpose Taekwondo, as the most popular martial art among Iranian sportsmen, might lead to injury for the athletes of this sport during competitions. We decided to report the incidence rate of injuries sustained by the athletes of this sport during national competitions. Methods All competitions of Iran national championship taekwondo league in 2006-2007 with 204 athletes were observed prospectively to detect the occurrence of injuries. The severity of injuries was classified into four groups (mild, moderate, severe, and critical) according to the involvement of medical care team in the contest, ability of the athletes to resume and duration of probable absence of injured athletes from future competitions and training sessions. Athlete-Exposure (A-E) was defined as the number of competitions multiplied by two. On this base, the rate of injury incidence per 1000 A-Es, the rate of injuries per time unit and the rate of injury occurred for each 100 athletes were considered as the major outcomes of this study. Results Of totally 1,338 A-Es, 93 injuries were recorded during the competitions. The rate of injury incidence was found to be 69.5 injuries per 1000 A-Es and the rate of injuries per minute of competitions was 0.023 which corresponded to 23.3 injuries per 1000 minutes of competitions. 45.6 injuries were occurred for each 100 athletes during the course of competitions. The most frequent injuries were mild (68.8%) and critical injuries (24.7%), followed by moderate and severe injuries; 4.3% and 2.1%, respectively. Conclusion The rate of injury we found was lower than that of western countries. In spite of finding the lower limbs as the most frequent place of injuries in other studies, we found the upper limbs as the most predisposed place of injuries which might be due to difference in the method of combat of Iranian athletes with other athletes. PMID:22375188

  20. NIH study finds sigmoidoscopy reduces colorectal cancer rates

    Cancer.gov

    Study finds that flexible sigmoidoscopy is effective in reducing the rates of new cases and deaths due to colorectal cancer. Researchers found that overall colorectal cancer mortality was reduced by 26 percent and incidence was reduced by 21 percent as a

  1. Classroom discipline skills and disruption rate: A correlational study

    NASA Astrophysics Data System (ADS)

    Dropik, Melonie Jane

    Very little has been done to quantify the relationship between the frequency with which teachers use discipline skills and disruption rate in high school settings. Most of the available research that examined this relationship empirically was done in elementary schools, while a few studies examined the junior high school setting. The present research examined whether the use of ten specific discipline skills were related to the rate of disruption in suburban high school science classrooms. The ten skills were selected based on their prevalence in the theoretical literature and the strength of the relationships reported in empirical studies of elementary and junior high classrooms. Each relationship was tested directionally at alpha = .01. The maximum experimentwise Type I error rate was .10. Disruption rate was measured by trained observers over five class periods in the Fall of the school year. The frequency of performing the ten skills was assessed using a student survey developed for this study. The ten skills were: (1) beginning class on time, (2) using routines, (3) waiting for student attention before speaking, (4) giving clear directions, (5) presenting material fast enough to hold students' attention, (6) requiring students to remain seated, (7) appearing confident, (8) stopping misbehavior quickly, (9) checking for student attentiveness, and (10) teaching to the bell. Appearing confident (r = --.697, p = .004) and quickly stopping misbehavior (r = --.709, p = .003) were significantly negatively related to disruption rate. The effect sizes for the confidence and stopping misbehavior variables were .49 and .50, respectively. At least half of the variation in disruption rate was attributable to the difference in the frequency of appearing confident and stopping misbehavior quickly. The eight other relationships produced nonsignificant results. The results raise questions about whether theories developed from observational and anecdotal evidence gathered in

  2. Resting energy expenditure of morbidly obese patients using indirect calorimetry: a systematic review.

    PubMed

    Kee, A-L; Isenring, E; Hickman, I; Vivanti, A

    2012-09-01

    The increasing proportion of acutely ill hospital patient admissions presenting with a morbidly obese body mass index (BMI ≥ 40 kg m(-2) ) as a comorbidity is an emerging clinical concern. Suboptimal food intake and malnutrition is prevalent in the acute care hospital setting. The energy requirements necessary to prevent malnutrition in acutely ill patients with morbid obesity remains unclear. The aim of this systematic review was to identify studies in the literature that have used indirect calorimetry to measure the resting energy expenditure of patients with morbid obesity to establish their minimum energy requirements and the implications for optimal feeding practices in acutely ill hospitalized patients. A total of 20 studies from PubMed, Cochrane Library and Embase met the inclusion criteria and were reviewed. All articles were graded using the Australian National Health and Medical Research Council levels of evidence and given a quality rating using the American Dietetic Association recommendations. Studies were categorized according to the mean BMI of its subjects. The most commonly measured resting energy expenditures for morbidly obese patients are between 2,000 and 3,000 kcal d(-1) (8,400-12,600 kJ d(-1) ). Activity and injury factors of acutely ill morbidly obese patients could result in significantly greater energy requirements for this patient group and are unlikely to be met by standard hospital menus. Establishing the minimum energy requirements for this population group will help inform adequate and accurate energy provision in the acute setting. Outcomes of underfeeding and overfeeding in morbidly obese patients warrant further research.

  3. [Autoaggression and pulse rate--a longitudinal study].

    PubMed

    Rohmann, U H; Elbing, U; Hartmann, H

    1988-12-01

    This article presents a model of autoaggressive behavior in which a distinction is made between determining and maintaining factors. Specific environmental, in particular social, and organismic variables are linked to them. The two types of variables interact, thus causing or maintaining autoaggressive behavior. A theory of autoaggression must therefore rely on multicausal/multimodal explanations. A connection between autoaggression and a high level of arousal suggests itself. In this single-case longitudinal study a comparison was made between heart rate and frequency of autoaggressive behavior. High heart rates were found to be correlated with low frequencies of autoaggressive behavior and vice versa. Decreasing autoaggressive behavior was coupled with increasing muscle relaxation and increasing motor activity. However, abnormally high heart rates were associated with both low and high levels of motor activity.

  4. Hybrid rocket fuel combustion and regression rate study

    NASA Technical Reports Server (NTRS)

    Strand, L. D.; Ray, R. L.; Anderson, F. A.; Cohen, N. S.

    1992-01-01

    The objectives of this study are to develop hybrid fuels (1) with higher regression rates and reduced dependence on fuel grain geometry and (2) that maximize potential specific impulse using low-cost materials. A hybrid slab window motor system was developed to screen candidate fuels - their combustion behavior and regression rate. Combustion behavior diagnostics consisted of video and high speed motion pictures coverage. The mean fuel regression rates were determined by before and after measurements of the fuel slabs. The fuel for this initial investigation consisted of hydroxyl-terminated polybutadiene binder with coal and aluminum fillers. At low oxidizer flux levels (and corresponding fuel regression rates) the filled-binder fuels burn in a layered fashion, forming an aluminum containing binder/coal surface melt that, in turn, forms into filigrees or flakes that are stripped off by the crossflow. This melt process appears to diminish with increasing oxidizer flux level. Heat transfer by radiation is a significant contributor, producing the desired increase in magnitude and reduction in flow dependency (power law exponent) of the fuel regression rate.

  5. 2007 Wholesale Power Rate Case Initial Proposal : Risk Analysis Study.

    SciTech Connect

    United States. Bonneville Power Administration.

    2005-11-01

    The Federal Columbia River Power System (FCRPS), operated on behalf of the ratepayers of the PNW by BPA and other Federal agencies, faces many uncertainties during the FY 2007-2009 rate period. Among these uncertainties, the largest revolve around hydro conditions, market prices and river operations for fish recovery. In order to provide a high probability of making its U.S. Treasury payments, BPA performs a Risk Analysis as part of its rate-making process. In this Risk Analysis, BPA identifies key risks, models their relationships, and then analyzes their impacts on net revenues (total revenues less expenses). BPA subsequently evaluates in the ToolKit Model the Treasury Payment Probability (TPP) resulting from the rates, risks, and risk mitigation measures described here and in the Wholesale Power Rate Development Study (WPRDS). If the TPP falls short of BPA's standard, additional risk mitigation revenues, such as PNRR and CRAC revenues are incorporated in the modeling in ToolKit until the TPP standard is met. Increased wholesale market price volatility and six years of drought have significantly changed the profile of risk and uncertainty facing BPA and its stakeholders. These present new challenges for BPA in its effort to keep its power rates as low as possible while fully meeting its obligations to the U.S. Treasury. As a result, the risk BPA faces in not receiving the level of secondary revenues that have been credited to power rates before receiving those funds is greater. In addition to market price volatility, BPA also faces uncertainty around the financial impacts of operations for fish programs in FY 2006 and in the FY 2007-2009 rate period. A new Biological Opinion or possible court-ordered change to river operations in FY 2006 through FY 2009 may reduce BPA's net revenues included Initial Proposal. Finally, the FY 2007-2009 risk analysis includes new operational risks as well as a more comprehensive analysis of non-operating risks. Both the operational

  6. Inherent limitations of fixed time servo-controlled radiometric calorimetry

    SciTech Connect

    Wetzel, J.R.; Duff, M.F.; Lemming, J.F.

    1987-01-01

    There has been some interest in low precision, short run time calorimetry measurements. This type of calorimetry measurement has been proposed for use when high precision measurements are not required, for example, to screen scrap containers to determine if there is enough material to be measured more accurately of for confirmatory measurements that only require low precision results. The equipment needed to make these measurements is a servo-controlled calorimeter with a sample preequilibration bath. The preequilibration bath temperature is set to the internal temperature of the calorimeter running at a fixed servo-controlled wattage level. The sample power value is determined at a fixed time form the sample loading into the calorimeter. There are some limitations and areas of uncertainties in the use of data obtained by this method. Data collected under controlled conditions demonstrate the limitations. Sample packaging, preequilibration time, and item wattage were chosen as the variables most likely to be encountered in a plant environment.

  7. The Philosophy and Feasibility of Dual Readout Calorimetry

    SciTech Connect

    Hauptman, John

    2006-10-27

    I will discuss the general physical ideas behind dual-readout calorimetry, their implementation in DREAM (Dual REAdout Module) with exact separation of scintillation and Cerenkov light, implementation with mixed light in DREAM fibers, anticipated implementation in PbWO4 crystals with applications to the 4th Concept detector and to CMS, use in high energy gamma-ray and cosmic ray astrophysics with Cerenkov and N2 fluorescent light, and implementation in the 4th Concept detector for muon identification.

  8. The upgraded CDF front end electronics for calorimetry

    SciTech Connect

    Drake, G.; Frei, D.; Hahn, S.R.; Nelson, C.A.; Segler, S.L.; Stuermer, W.

    1991-11-01

    The front end electronics used in the calorimetry of the CDF detector has been upgraded to meet system requirements for higher expected luminosity. A fast digitizer utilizing a 2 {mu}Sec, 16 bit ADC has been designed and built. Improvements to the front end trigger circuitry have been implemented, including the production of 900 new front end modules. Operational experience with the previous system is presented, with discussion of the problems and performance goals.

  9. 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.

  10. A parametric study of rate of advance and area coverage rate performance of synthetic aperture radar.

    SciTech Connect

    Raynal, Ann Marie; William H. Hensley, Jr.; Burns, Bryan L.; Doerry, Armin Walter

    2014-11-01

    The linear ground distance per unit time and ground area covered per unit time of producing synthetic aperture radar (SAR) imagery, termed rate of advance (ROA) and area coverage rate (ACR), are important metrics for platform and radar performance in surveillance applications. These metrics depend on many parameters of a SAR system such as wavelength, aircraft velocity, resolution, antenna beamwidth, imaging mode, and geometry. Often the effects of these parameters on rate of advance and area coverage rate are non-linear. This report addresses the impact of different parameter spaces as they relate to rate of advance and area coverage rate performance.

  11. Effects of energy supplementation on energy losses and nitrogen balance of steers fed green-chopped wheat pasture I. Calorimetry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Providing an energy supplement to cattle grazing high-quality wheat pasture can increase average daily gain; however the effects on greenhouse gas emissions are not known. Therefore we used 10 British cross-bred steers (initial weight: 206 ± 10.7 kg) in a respiration calorimetry study to evaluate t...

  12. Canadian Pharmacy Practice Residents’ Projects: Publication Rates and Study Characteristics

    PubMed Central

    Hung, Michelle; Duffett, Mark

    2013-01-01

    Background: Research projects are a key component of pharmacy residents’ education. Projects represent both a large investment of effort for each resident (up to 10 weeks over the residency year) and a large body of research (given that there are currently over 150 residency positions in Canada annually). Publication of results is a vital part of the dissemination of information gleaned from these projects. Objectives: To determine the publication rate for research projects performed under the auspices of accredited English-language hospital pharmacy residency programs in Canada and to describe the study characteristics of residency projects performed in Ontario from 1999/2000 to 2008/2009. Methods: Lists of residents and project titles for the period of interest were obtained from residency coordinators. PubMed, CINAHL, the Canadian Journal of Hospital Pharmacy, and Google were searched for evidence of publication of each project identified, as an abstract or presentation at a meeting, a letter to the editor, or a full-text manuscript. The library holdings of the University of Toronto were reviewed to determine study characteristics of the Ontario residency projects. Results: For the objective of this study relating to publication rate, 518 projects were included. The overall publication rate was 32.2% (60 [35.9%] as abstracts and 107 [64.1%] as full-text manuscripts). Publication in pharmacy-specific journals (66 [61.7%] of 107 full-text manuscripts) was more frequent than publication in non-pharmacy-specific journals. The publication rate of projects as full-text manuscripts remained stable over time. Of the 202 Ontario residency projects archived in the University of Toronto’s library, most were cohort studies (83 [41.1%]), and the most common topic was efficacy and/or safety of a medication (46 [22.8%]). Conclusions: Most hospital pharmacy residents’ projects were unpublished, and the publication rate of projects as full-text manuscripts has not

  13. Semiparametric Stochastic Modeling of the Rate Function in Longitudinal Studies

    PubMed Central

    Zhu, Bin; Taylor, Jeremy M.G.; Song, Peter X.-K.

    2011-01-01

    In longitudinal biomedical studies, there is often interest in the rate functions, which describe the functional rates of change of biomarker profiles. This paper proposes a semiparametric approach to model these functions as the realizations of stochastic processes defined by stochastic differential equations. These processes are dependent on the covariates of interest and vary around a specified parametric function. An efficient Markov chain Monte Carlo algorithm is developed for inference. The proposed method is compared with several existing methods in terms of goodness-of-fit and more importantly the ability to forecast future functional data in a simulation study. The proposed methodology is applied to prostate-specific antigen profiles for illustration. Supplementary materials for this paper are available online. PMID:22423170

  14. Recommendations for improved data processing from expired gas analysis indirect calorimetry.

    PubMed

    Robergs, Robert A; Dwyer, Dan; Astorino, Todd

    2010-02-01

    There is currently no universally recommended and accepted method of data processing within the science of indirect calorimetry for either mixing chamber or breath-by-breath systems of expired gas analysis. Exercise physiologists were first surveyed to determine methods used to process oxygen consumption ((.)VO2) data, and current attitudes to data processing within the science of indirect calorimetry. Breath-by-breath datasets obtained from indirect calorimetry during incremental exercise were then used to demonstrate the consequences of commonly used time, breath and digital filter post-acquisition data processing strategies. Assessment of the variability in breath-by-breath data was determined using multiple regression based on the independent variables ventilation (VE), and the expired gas fractions for oxygen and carbon dioxide, FEO2 and FECO2, respectively. Based on the results of explanation of variance of the breath-by-breath (.)VO2 data, methods of processing to remove variability were proposed for time-averaged, breath-averaged and digital filter applications. Among exercise physiologists, the strategy used to remove the variability in (.)VO2 measurements varied widely, and consisted of time averages (30 sec [38%], 60 sec [18%], 20 sec [11%], 15 sec [8%]), a moving average of five to 11 breaths (10%), and the middle five of seven breaths (7%). Most respondents indicated that they used multiple criteria to establish maximum ((.)VO2 ((.)VO2max) including: the attainment of age-predicted maximum heart rate (HR(max)) [53%], respiratory exchange ratio (RER) >1.10 (49%) or RER >1.15 (27%) and a rating of perceived exertion (RPE) of >17, 18 or 19 (20%). The reasons stated for these strategies included their own beliefs (32%), what they were taught (26%), what they read in research articles (22%), tradition (13%) and the influence of their colleagues (7%). The combination of VE, FEO2 and FECO2 removed 96-98% of (.)VO2 breath-by-breath variability in incremental

  15. Chip calorimetry for evaluation of biofilm treatment with biocides, antibiotics, and biological agents.

    PubMed

    Morais, Frida Mariana; Buchholz, Friederike; Maskow, Thomas

    2014-01-01

    Any growth or bioconversion in biofilms is accompanied by the release of heat. The heat (in J) is tightly related to the stoichiometry of the respective process via law of Hess, and the heat production rate (in W or J/s) is additionally related to the process kinetics. This heat and the heat production rate can nowadays be measured by modern calorimetry with extremely high sensitivity. Flow-through calorimetry allows the measurement of bioprocesses in biofilms in real time, without the need of invasive sample preparation and disturbing of biofilm processes. Furthermore, it can be applied for long-term measurements and is even applicable to turbid media. Chip or miniaturized calorimeters have the additional advantages of extremely short thermal equilibration times and the requirement of very small amounts of media and chemicals. The precision of flow-through chip calorimeters (about 3 mW/L) allows the detection of early stages of biofilm development (about 10(5) bacteria cm(-2)).

  16. VO2 and VCO2 variabilities through indirect calorimetry instrumentation.

    PubMed

    Cadena-Méndez, Miguel; Escalante-Ramírez, Boris; Azpiroz-Leehan, Joaquín; Infante-Vázquez, Oscar

    2013-01-01

    The aim of this paper is to understand how to measure the VO2 and VCO2 variabilities in indirect calorimetry (IC) since we believe they can explain the high variation in the resting energy expenditure (REE) estimation. We propose that variabilities should be separately measured from the VO2 and VCO2 averages to understand technological differences among metabolic monitors when they estimate the REE. To prove this hypothesis the mixing chamber (MC) and the breath-by-breath (BbB) techniques measured the VO2 and VCO2 averages and their variabilities. Variances and power spectrum energies in the 0-0.5 Hertz band were measured to establish technique differences in steady and non-steady state. A hybrid calorimeter with both IC techniques studied a population of 15 volunteers that underwent the clino-orthostatic maneuver in order to produce the two physiological stages. The results showed that inter-individual VO2 and VCO2 variabilities measured as variances were negligible using the MC while variabilities measured as spectral energies using the BbB underwent 71 and 56% (p < 0.05), increase respectively. Additionally, the energy analysis showed an unexpected cyclic rhythm at 0.025 Hertz only during the orthostatic stage, which is new physiological information, not reported previusly. The VO2 and VCO2 inter-individual averages increased to 63 and 39% by the MC (p < 0.05) and 32 and 40% using the BbB (p < 0.1), respectively, without noticeable statistical differences among techniques. The conclusions are: (a) metabolic monitors should simultaneously include the MC and the BbB techniques to correctly interpret the steady or non-steady state variabilities effect in the REE estimation, (b) the MC is the appropriate technique to compute averages since it behaves as a low-pass filter that minimizes variances, (c) the BbB is the ideal technique to measure the variabilities since it can work as a high-pass filter to generate discrete time series able to accomplish

  17. Differential scanning calorimetry: An invaluable tool for a detailed thermodynamic characterization of macromolecules and their interactions

    PubMed Central

    Chiu, Michael H.; Prenner, Elmar J.

    2011-01-01

    Differential Scanning Calorimetry (DSC) is a highly sensitive technique to study the thermotropic properties of many different biological macromolecules and extracts. Since its early development, DSC has been applied to the pharmaceutical field with excipient studies and DNA drugs. In recent times, more attention has been applied to lipid-based drug delivery systems and drug interactions with biomimetic membranes. Highly reproducible phase transitions have been used to determine values, such as, the type of binding interaction, purity, stability, and release from a drug delivery mechanism. This review focuses on the use of DSC for biochemical and pharmaceutical applications. PMID:21430954

  18. Kinetic analysis of gluconate phosphorylation by human gluconokinase using isothermal titration calorimetry.

    PubMed

    Rohatgi, Neha; Guðmundsson, Steinn; Rolfsson, Óttar

    2015-11-30

    Gluconate is a commonly encountered nutrient, which is degraded by the enzyme gluconokinase to generate 6-phosphogluconate. Here we used isothermal titration calorimetry to study the properties of this reaction. ΔH, KM and kcat are reported along with substrate binding data. We propose that the reaction follows a ternary complex mechanism, with ATP binding first. The reaction is inhibited by gluconate, as it binds to an Enzyme-ADP complex forming a dead-end complex. The study exemplifies that ITC can be used to determine mechanisms of enzyme catalyzed reactions, for which it is currently not commonly applied.

  19. Hydrogen Generation Rate Scoping Study of DOW Corning Antifoam Agent

    SciTech Connect

    Crawford, Charles

    2005-09-27

    conservatively bounds hydrogen generation rates (HGRs) from antifoam-containing simulants if the antifoam organic components are treated the same as other native organics. Tests that used the combination of radiolysis and thermolysis conducted on simulants containing antifoam produced measured hydrogen that was bounded by the WTP correlation. These tests used the bounding WTP temperature of 90 C and a dose rate of 1.8 x 10{sup 5} rad/hr. This dose rate is about ten times higher than the dose rate equivalent calculated for a bounding Hanford sludge slurry composition of 10 Ci/L, or 2 x 10{sup 4} rad/hr. Hydrogen was measured using a quadrupole mass spectroscopy instrument. Based on the analyses from the 4wt% and 10wt% antifoam samples, it is expected that the HGR results are directly proportional to the antifoam concentration added. A native organic-containing simulant that did not contain any added antifoam also produced a measurable radiolytic/thermal hydrogen rates that was in bounded by the WTP correlation. A base simulant with no added organic produced a measurable radiolytic/thermal HGR that was {approx}2X higher than the predicted HGR. Analysis of antifoam-containing simulants after prolonged irradiation of 52 Mrad and heating (23 days at 90 C) indicates that essentially all of the PDMS and greater than 60% of the PPG components are degraded, likely to lower molecular weight species. The antifoam components were analyzed by extraction from the salt simulants, followed by gel permeation chromatography (GPC) by personnel at Dow Corning. A more detailed study of the antifoam degradation and product formation from radiolysis and thermolysis is currently in progress at SRNL. That study uses a dose rate of about 2 x 10{sup 4} rad/hr and bounding temperatures of 90 C. Results from that study will be reported in a future report.

  20. Parametric study of injection rates with solenoid injectors in an injection quantity and rate measuring device

    DOE PAGES

    Busch, Stephen; Miles, Paul C.

    2015-03-31

    A Moehwald HDA (HDA is a German acronym: Hydraulischer Druckanstieg: hydraulic pressure increase) injection quantity and rate measuring unit is used to investigate injection rates obtained with a fast-acting, preproduction diesel solenoid injector. Experimental parametric variations are performed to determine their impact on measured injection rate traces. A pilot–main injection strategy is investigated for various dwell times; these preproduction injectors can operate with very short dwell times with distinct pilot and main injection events. Dwell influences the main injection rate shape. Furthermore, a comparison between a diesel-like fuel and a gasoline-like fuel shows that injection rates are comparable for amore » single injection but dramatically different for multiple injections with short dwells.« less

  1. Parametric study of injection rates with solenoid injectors in an injection quantity and rate measuring device

    SciTech Connect

    Busch, Stephen; Miles, Paul C.

    2015-03-31

    A Moehwald HDA (HDA is a German acronym: Hydraulischer Druckanstieg: hydraulic pressure increase) injection quantity and rate measuring unit is used to investigate injection rates obtained with a fast-acting, preproduction diesel solenoid injector. Experimental parametric variations are performed to determine their impact on measured injection rate traces. A pilot–main injection strategy is investigated for various dwell times; these preproduction injectors can operate with very short dwell times with distinct pilot and main injection events. Dwell influences the main injection rate shape. Furthermore, a comparison between a diesel-like fuel and a gasoline-like fuel shows that injection rates are comparable for a single injection but dramatically different for multiple injections with short dwells.

  2. Assessing Mixing Quality of a Copovidone-TPGS Hot Melt Extrusion Process with Atomic Force Microscopy and Differential Scanning Calorimetry.

    PubMed

    Lamm, Matthew S; DiNunzio, James; Khawaja, Nazia N; Crocker, Louis S; Pecora, Anthony

    2016-02-01

    Atomic force microscopy (AFM) and modulated differential scanning calorimetry (mDSC) were used to evaluate the extent of mixing of a hot melt extrusion process for producing solid dispersions of copovidone and D-α-tocopherol polyethylene glycol 1000 succinate (TPGS 1000). In addition to composition, extrusion process parameters of screw speed and thermal quench rate were varied. The data indicated that for 10% TPGS and 300 rpm screw speed, the mixing was insufficient to yield a single-phase amorphous material. AFM images of the extrudate cross section for air-cooled material indicate round domains 200 to 700 nm in diameter without any observed alignment resulting from the extrusion whereas domains in extrudate subjected to chilled rolls were elliptical in shape with uniform orientation. Thermal analysis indicated that the domains were predominantly semi-crystalline TPGS. For 10% TPGS and 600 rpm screw speed, AFM and mDSC data were consistent with that of a single-phase amorphous material for both thermal quench rates examined. When the TPGS concentration was reduced to 5%, a single-phase amorphous material was achieved for all conditions even the slowest screw speed studied (150 rpm).

  3. Articulation Rate in Preschool Children: A 3-Year Longitudinal Study

    ERIC Educational Resources Information Center

    Walker, Jean F.; Archibald, Lisa M. D.

    2006-01-01

    Background: Speaking rate has implications for both clinical practice and an understanding of normal and disordered communication processes. Fundamental information on speaking rate is required by the clinician for the appropriate management of those disorders with disturbances of rate or those in which rate modification strategies are applied.…

  4. Raman detected differential scanning calorimetry of polymorphic transformations in acetaminophen.

    PubMed

    Kauffman, John F; Batykefer, Linda M; Tuschel, David D

    2008-12-15

    Acetaminophen is known to crystallize in three polymorphic forms. Thermally induced transformations between the crystalline forms and the super-cooled liquid have been observed by differential scanning calorimetry (DSC), but the assignment of calorimetric transitions to specific polymorphic transformations remains challenging, because the transition temperatures for several transformations are close to one another, and the characteristics of the observed transitions depend on experimental variables that are often poorly controlled. This paper demonstrates the simultaneous application of DSC and Raman microscopy for the observation of thermally driven transitions between polymorphs of pharmaceutical materials. Raman detected differential scanning calorimetry (RD-DSC) has been used to monitor the DSC thermograms of super-cooled liquid acetaminophen and confirms the assignment of two exothermic transitions to specific polymorphic transformations. Principal component analysis of the Raman spectra have been used to determine the number of independent components that participate in the phase transformations, and multivariate regression has been used to determine transition temperatures from the spectral data. The influence of the laser excitation source on measured DSC thermograms has also been investigated, and it has been demonstrated that a baseline shift occurs in RD-DSC when a polymorphic transformation occurs between crystalline and amorphous forms. RD-DSC has been used to examine the influence of sample aging and sample pan configuration on the observed polymorphic transformations, and both of these variables were found to influence the thermal behavior of the sample. The results demonstrate the advantage of simultaneous Raman spectroscopy and differential scanning calorimetry for the unambiguous assignment of thermally driven polymorphic transformations.

  5. Technical memo on PbF/sub 2/ as a Cherenkov radiator for EM calorimetry

    SciTech Connect

    Anderson, D.F.

    1989-06-26

    It is apparent that the ever increasing rates and radiation levels found in high-energy physics are excluding more and more instrumental techniques. Those techniques that are remaining are often pushed to their theoretical limits. This situation reaches an extreme at the proposed luminosity of the SSC. Also, it is fair to say that at the SSC, after the accelerator itself, calorimetry will be the next most important physics tool. Therefore, we should be ever alert to new calorimetry techniques which may operate in this demanding environment. The material lead fluoride, PbF/sub 2/, has a real potential of yielding a very compact, high-resolution electromagnetic calorimeter that is both fast and radiation hard. PbF/sub 2/ is not a scintillator but a Cherenkov radiator like lead glass, but with a radiation length even harder shorter than of BGO. This memo discusses this property as well as comparison PbF/sub 2/ to other scintillating materials. 2 refs., 14 figs., 1 tab.

  6. 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.

  7. Thermodynamics of actinide complexation in solution at elevated temperatures: application of variable-temperature titration calorimetry.

    PubMed

    Rao, Linfeng

    2007-06-01

    Studies of actinide complexation in solution at elevated temperatures provide insight into the effect of solvation and the energetics of complexation, and help to predict the chemical behavior of actinides in nuclear waste processing and disposal where temperatures are high. This tutorial review summarizes the data on the complexation of actinides at elevated temperatures and describes the methodology for thermodynamic measurements, with the emphasis on variable-temperature titration calorimetry, a highly valuable technique to determine the enthalpy and, under appropriate conditions, the equilibrium constants of complexation as well.

  8. Catalytic reaction energetics by single crystal adsorption calorimetry: hydrocarbons on Pt(111).

    PubMed

    Lytken, Ole; Lew, Wanda; Campbell, Charles T

    2008-10-01

    Single crystal adsorption calorimetry provides essential information about the energetics of surface reactions on well-defined surfaces where the adsorbed reaction products can be clearly identified. In this tutorial review, we cover the essentials of that technique, with emphasis on our lab's recent advances in sensitivity and temperature range, and demonstrate what can be achieved through a review of selected example studies concerning adsorption and dehydrogenation of hydrocarbons on Pt(111). A fairly complete reaction enthalpy diagram is presented for the dehydrogenation of cyclohexane to benzene on Pt(111).

  9. Fragility of supercooled liquids from differential scanning calorimetry traces: theory and experiment.

    PubMed

    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.

  10. Fragility of supercooled liquids from differential scanning calorimetry traces: Theory and experiment

    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.

  11. Water-based scintillators for large-scale liquid calorimetry

    SciTech Connect

    Winn, D.R.; Raftery, D.

    1985-02-01

    We have investigated primary and secondary solvent intermediates in search of a recipe to create a bulk liquid scintillator with water as the bulk solvent and common fluors as the solutes. As we are not concerned with energy resolution below 1 MeV in large-scale experiments, light-output at the 10% level of high-quality organic solvent based scintillators is acceptable. We have found encouraging performance from industrial surfactants as primary solvents for PPO and POPOP. This technique may allow economical and environmentally safe bulk scintillator for kiloton-sized high energy calorimetry.

  12. Scintillating tile/fiber calorimetry development at FNAL

    NASA Astrophysics Data System (ADS)

    Foster, G. W.; Freeman, J.; Hagstrom, R.

    1991-07-01

    The technique of calorimetry using scintillating tiles with waveshifting fibers imbedded in them for readout has been refined for use in SSC test calorimeters and for the CDF Endplug upgrade. The technique offers high light yield, good spatial uniformity, flexible readout mechanics and a very small "readout crack". Various production techniques have been developed and optimized, including control and correction of scintillator plate uniformity, techniques for splicing plastic fibers with low light losses, and laser-cutting of the groove in which the fiber is placed.

  13. Cell asymmetry correction for temperature modulated differential scanning calorimetry

    SciTech Connect

    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.

  14. Differential Scanning Calorimetry (DSC) for the Analysis of Activated Carbon

    DTIC Science & Technology

    1991-10-01

    impregnation procedures . It is believed that Sutcliffe-Speakman is currently using coconut - shell as the carbon precursor (instead of the New Zealand coal...microstructure facilitate the adsorption process whereby all the undesirable materials are retained. For military deployment, the activated carbon is...AD-A245 899 H.P ’ l N dI dUenm / DIFFERENTIAL SCANNING CALORIMETRY (DSC) FOR THE ANALYSIS OF ACTIVATED CARBON (U) by S.H.C. a and L.E. Cameron DTIC x

  15. Why are breastfeeding rates low in Lebanon? a qualitative study

    PubMed Central

    2011-01-01

    Background Breastfeeding is a cost-effective public health intervention that reduces infant morbidity and mortality in developing countries. In Lebanon, breastfeeding exclusivity and continuation rates are disappointingly low. This qualitative study aims at identifying barriers and promoters of breastfeeding in the Lebanese context by exploring mothers' perceptions and experiences in breastfeeding over a one year period. Methods We conducted focus group discussions in three hospitals in Beirut, Lebanon, and followed up 36 breastfeeding mothers with serial in-depth interviews for one year post-partum or until breastfeeding discontinuation. Results Themes generated from baseline interviews revealed several positive and negative perceptions of breastfeeding. Longitudinal follow up identified insufficient milk, fear of weight gain or breast sagging, pain, sleep deprivation, exhaustion, or maternal employment, as reasons for early breastfeeding discontinuation. Women who continued breastfeeding for one year were more determined to succeed and overcome any barrier, relying mostly on family support and proper time management. Conclusions Increasing awareness of future mothers about breast feeding difficulties, its benefits to children, mothers, and society at large may further promote breastfeeding, and improve exclusivity and continuation rates in Lebanon. A national strategy for early intervention during school years to increase young women's awareness may improve their self-confidence and determination to succeed in breastfeeding later. Moreover, prolonging maternity leave, having day-care facilities at work, creation of lactation peer support groups and hotlines, and training of doctors and nurses in proper lactation support may positively impact breastfeeding exclusivity and continuation rates. Further research is needed to assess the effectiveness of proposed interventions in the Lebanese context. PMID:21878101

  16. Differential scanning calorimetry in life science: thermodynamics, stability, molecular recognition and application in drug design.

    PubMed

    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.

  17. Calorimetry exchange program. Annual data report, Calendar Year 1993

    SciTech Connect

    Barnett, T.M.

    1996-08-01

    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. The data report includes summary tables for each measurement and charts showing the performance of each laboratory. Comparisons are made to the accepted values for the exchange sample and to data previously reported by that laboratory. This information is presented, in the form of quarterly and annual reports, intended for use by Exchange participants in measurement control programs, or to indicate when bias corrections may be appropriate. No attempt, however, has been made to standardize methods or frequency of data collection, calibration, or operating procedures. Direct comparisons between laboratories may, therefore, be misleading since data have not been collected to the same precision or for the same time periods. A meeting of the participants of the Calorimetry Exchange is held annually at EG&G Mound Applied Technologies. The purposes of this meeting are to discuss measurement differences, problems, and new measurement capabilities, and to determine the additional activities needed to fulfill the goals of the Exchange.

  18. Isothermal titration calorimetry: general formalism using binding polynomials.

    PubMed

    Freire, Ernesto; Schön, Arne; Velazquez-Campoy, Adrian

    2009-01-01

    The theory of the binding polynomial constitutes a very powerful formalism by which many experimental biological systems involving ligand binding can be analyzed under a unified framework. The analysis of isothermal titration calorimetry (ITC) data for systems possessing more than one binding site has been cumbersome because it required the user to develop a binding model to fit the data. Furthermore, in many instances, different binding models give rise to identical binding isotherms, making it impossible to discriminate binding mechanisms using binding data alone. One of the main advantages of the binding polynomials is that experimental data can be analyzed by employing a general model-free methodology that provides essential information about the system behavior (e.g., whether there exists binding cooperativity, whether the cooperativity is positive or negative, and the magnitude of the cooperative energy). Data analysis utilizing binding polynomials yields a set of binding association constants and enthalpy values that conserve their validity after the correct model has been determined. In fact, once the correct model is validated, the binding polynomial parameters can be immediately translated into the model specific constants. In this chapter, we describe the general binding polynomial formalism and provide specific theoretical and experimental examples of its application to isothermal titration calorimetry.

  19. Glossoscolex paulistus extracellular hemoglobin (HbGp) oligomeric dissociation upon interaction with sodium dodecyl sulfate: Isothermal titration calorimetry (ITC).

    PubMed

    Alves, Fernanda Rosa; Carvalho, Francisco Adriano O; Carvalho, José Wilson P; Tabak, Marcel

    2014-10-01

    Annelid erythrocruorins are respiratory proteins with high cooperativity and low autoxidation rates. The giant extracellular hemoglobin of the earthworm, Glossoscolex paulistus (HbGp), has a molecular mass of 3.6 MDa. In this work, isothermal titration calorimetry (ITC), together with DLS and fluorescence emission have been used to investigate the interaction of SDS with the HbGp in the oxy-form, at pH 7.0. Our ITC and DLS results show that addition of SDS induces oxy-HbGp oligomeric dissociation, while a small amount of protein aggregation is observed only by DLS. Moreover, the oligomeric dissociation process is favored at lower protein concentrations. The temperature effect does not influence significantly the interaction of SDS with the hemoglobin, due to the similarities presented by the critical aggregation concentration (cac) and critical micelle concentration (cmc') for the mixtures. The increase of oxy-HbGp concentration leads to a slight variation of the cac values for the SDS-oxy-HbGp mixture, attributed mainly to the noncooperative electrostatic binding of surfactant to protein. However, the cmc' values increase considerably, associated to a more cooperative hydrophobic binding. Complementary pyrene fluorescence emission studies show formation of pre-micellar structures of the mixture already at lower SDS concentrations. This study opens the possibility of the evaluation of the surfactant effect on the hemoglobin stability by ITC, which is made for the first time with this extracellular hemoglobin.

  20. Differences in resting metabolic rate and physical activity patterns in lean and overweight/obese pregnant women

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Energy requirements vary during pregnancy due to changes in physical activity (PA) and maternal fat stores. This study measured resting metabolic rate (RMR) and PA patterns in healthy lean and overweight/obese (OW) pregnant women. RMR was measured using indirect calorimetry (MOXUS), activity pattern...

  1. Application of differential scanning calorimetry in evaluation of solid state interactions in tablets containing acetaminophen.

    PubMed

    Mazurek-Wadołkowska, Edyta; Winnicka, Katarzyna; Czajkowska-Kośnik, Anna; Czyzewska, Urszula; Miltyk, Wojciech

    2013-01-01

    Differential scanning calorimetry (DSC) is an analytical procedure used to determine the differences in the heat flow generated or absorbed by the sample. This method allows to assess purity and polymorphic form of drug compounds, to detect interactions between ingredients of solid dosage forms and to analyze stability of solid formulations. The aim of this study was the assessment of compatibility between acetaminophen (API) and different types of excipients often used in tablets compression: polyvinylpyrrolidone, crospovidone, pregelatinized starch, microcrystalline cellulose and magnesium stearate by differential scanning calorimetry. The study contains results of thermal analysis of excipients and individually performed mixtures of these substances with acetaminophen before and after compression and after 6 months storage of tablets at different temperature and relative humidity conditions (25 +/- 2 degrees C /40 +/- 5% RH, 25 +/- 2 degrees C /60 +/- 5% RH, 40 +/- 2 degrees C /75 +/- 5% RH) for a period of 6 months. To detect possible changes of API chemical structure, gas chromatography-mass spectrometry (GC-MS) was also applied. GC-MS with electron impact ionization (EI) was employed to determine the fragmentation pattern of API. It was shown that the developed formulations showed excellent compatibility among all excipients used except Kollidon CL. The interaction with Kollidon CL is probably a result of a physical reaction as confirmed by GC-MS analyses. Obtained results revealed that DSC can be successfully applied to evaluate possible incompatibilities between acetaminophen and Kollidon.

  2. Detectors for Linear Colliders: Calorimetry at a Future Electron-Positron Collider (3/4)

    ScienceCinema

    None

    2016-07-12

    Calorimetry will play a central role in determining the physics reach at a future e+e- collider. The requirements for calorimetry place the emphasis on achieving an excellent jet energy resolution. The currently favoured option for calorimetry at a future e+e- collider is the concept of high granularity particle flow calorimetry. Here granularity and a high pattern recognition capability is more important than the single particle calorimetric response. In this lecture I will describe the recent progress in understanding the reach of high granularity particle flow calorimetry and the related R&D; efforts which concentrate on test beam demonstrations of the technological options for highly granular calorimeters. I will also discuss alternatives to particle flow, for example the technique of dual readout calorimetry.

  3. Detectors for Linear Colliders: Calorimetry at a Future Electron-Positron Collider (3/4)

    SciTech Connect

    2010-02-17

    Calorimetry will play a central role in determining the physics reach at a future e+e- collider. The requirements for calorimetry place the emphasis on achieving an excellent jet energy resolution. The currently favoured option for calorimetry at a future e+e- collider is the concept of high granularity particle flow calorimetry. Here granularity and a high pattern recognition capability is more important than the single particle calorimetric response. In this lecture I will describe the recent progress in understanding the reach of high granularity particle flow calorimetry and the related R&D; efforts which concentrate on test beam demonstrations of the technological options for highly granular calorimeters. I will also discuss alternatives to particle flow, for example the technique of dual readout calorimetry.

  4. Advanced ion beam calorimetry for the test facility ELISE

    NASA Astrophysics Data System (ADS)

    Nocentini, R.; Bonomo, F.; Pimazzoni, A.; Fantz, U.; Franzen, P.; Fröschle, M.; Heinemann, B.; Pasqualotto, R.; Riedl, R.; Ruf, B.; Wünderlich, D.

    2015-04-01

    The negative ion source test facility ELISE (Extraction from a Large Ion Source Experiment) is in operation since beginning of 2013 at the Max-Planck-Institut für Plasmaphysik (IPP) in Garching bei München. The large radio frequency driven ion source of ELISE is about 1×1 m2 in size (1/2 the ITER source) and can produce a plasma for up to 1 h. Negative ions can be extracted and accelerated by an ITER-like extraction system made of 3 grids with an area of 0.1 m2, for 10 s every 3 minutes. A total accelerating voltage of up to 60 kV is available, i.e. a maximum ion beam power of about 1.2 MW can be produced. ELISE is equipped with several beam diagnostic tools for the evaluation of the beam characteristics. In order to evaluate the beam properties with a high level of detail, a sophisticated diagnostic calorimeter has been installed in the test facility at the end of 2013, starting operation in January 2014. The diagnostic calorimeter is split into 4 copper plates with separate water calorimetry for each of the plates. Each calorimeter plate is made of 15×15 copper blocks, which act as many separate inertial calorimeters and are attached to a copper plate with an embedded cooling circuit. The block geometry and the connection with the cooling plate are optimized to accurately measure the time-averaged power of the 10 s ion beam. The surface of the blocks is covered with a black coating that allows infrared (IR) thermography which provides a 2D profile of the beam power density. In order to calibrate the IR thermography, 48 thermocouples are installed in as many blocks, arranged in two vertical and two horizontal rows. The paper describes the beam calorimetry in ELISE, including the methods used for the IR thermography, the water calorimetry and the analytical methods for beam profile evaluation. It is shown how the maximum beam inhomogeneity amounts to 13% in average. The beam divergence derived by IR thermography ranges between 1° and 4° and correlates

  5. Advanced ion beam calorimetry for the test facility ELISE

    SciTech Connect

    Nocentini, R. Fantz, U.; Franzen, P.; Fröschle, M.; Heinemann, B.; Riedl, R.; Ruf, B.; Wünderlich, D.; Bonomo, F.; Pimazzoni, A.; Pasqualotto, R.

    2015-04-08

    The negative ion source test facility ELISE (Extraction from a Large Ion Source Experiment) is in operation since beginning of 2013 at the Max-Planck-Institut für Plasmaphysik (IPP) in Garching bei München. The large radio frequency driven ion source of ELISE is about 1×1 m{sup 2} in size (1/2 the ITER source) and can produce a plasma for up to 1 h. Negative ions can be extracted and accelerated by an ITER-like extraction system made of 3 grids with an area of 0.1 m{sup 2}, for 10 s every 3 minutes. A total accelerating voltage of up to 60 kV is available, i.e. a maximum ion beam power of about 1.2 MW can be produced. ELISE is equipped with several beam diagnostic tools for the evaluation of the beam characteristics. In order to evaluate the beam properties with a high level of detail, a sophisticated diagnostic calorimeter has been installed in the test facility at the end of 2013, starting operation in January 2014. The diagnostic calorimeter is split into 4 copper plates with separate water calorimetry for each of the plates. Each calorimeter plate is made of 15×15 copper blocks, which act as many separate inertial calorimeters and are attached to a copper plate with an embedded cooling circuit. The block geometry and the connection with the cooling plate are optimized to accurately measure the time-averaged power of the 10 s ion beam. The surface of the blocks is covered with a black coating that allows infrared (IR) thermography which provides a 2D profile of the beam power density. In order to calibrate the IR thermography, 48 thermocouples are installed in as many blocks, arranged in two vertical and two horizontal rows. The paper describes the beam calorimetry in ELISE, including the methods used for the IR thermography, the water calorimetry and the analytical methods for beam profile evaluation. It is shown how the maximum beam inhomogeneity amounts to 13% in average. The beam divergence derived by IR thermography ranges between 1° and 4° and

  6. Estimating glomerular filtration rate in a population-based study

    PubMed Central

    Shankar, Anoop; Lee, Kristine E; Klein, Barbara EK; Muntner, Paul; Brazy, Peter C; Cruickshanks, Karen J; Nieto, F Javier; Danforth, Lorraine G; Schubert, Carla R; Tsai, Michael Y; Klein, Ronald

    2010-01-01

    Background: Glomerular filtration rate (GFR)-estimating equations are used to determine the prevalence of chronic kidney disease (CKD) in population-based studies. However, it has been suggested that since the commonly used GFR equations were originally developed from samples of patients with CKD, they underestimate GFR in healthy populations. Few studies have made side-by-side comparisons of the effect of various estimating equations on the prevalence estimates of CKD in a general population sample. Patients and methods: We examined a population-based sample comprising adults from Wisconsin (age, 43–86 years; 56% women). We compared the prevalence of CKD, defined as a GFR of <60 mL/min per 1.73 m2 estimated from serum creatinine, by applying various commonly used equations including the modification of diet in renal disease (MDRD) equation, Cockcroft–Gault (CG) equation, and the Mayo equation. We compared the performance of these equations against the CKD definition of cystatin C >1.23 mg/L. Results: We found that the prevalence of CKD varied widely among different GFR equations. Although the prevalence of CKD was 17.2% with the MDRD equation and 16.5% with the CG equation, it was only 4.8% with the Mayo equation. Only 24% of those identified to have GFR in the range of 50–59 mL/min per 1.73 m2 by the MDRD equation had cystatin C levels >1.23 mg/L; their mean cystatin C level was only 1 mg/L (interquartile range, 0.9–1.2 mg/L). This finding was similar for the CG equation. For the Mayo equation, 62.8% of those patients with GFR in the range of 50–59 mL/min per 1.73 m2 had cystatin C levels >1.23 mg/L; their mean cystatin C level was 1.3 mg/L (interquartile range, 1.2–1.5 mg/L). The MDRD and CG equations showed a false-positive rate of >10%. Discussion: We found that the MDRD and CG equations, the current standard to estimate GFR, appeared to overestimate the prevalence of CKD in a general population sample. PMID:20730018

  7. Unraveling the thermodynamics and kinetics of RNA assembly: surface plasmon resonance, isothermal titration calorimetry, and circular dichroism.

    PubMed

    Hoogstraten, Charles G; Sumita, Minako; White, Neil A

    2014-01-01

    The mechanisms and driving forces of the assembly of RNA tertiary structure are a topic of much current interest. In several systems, including our own work in the docking transition of the hairpin ribozyme, intramolecular RNA tertiary folding has been converted into an intermolecular binding event, allowing the full power of contemporary biophysical techniques to be brought to bear on the analysis. We review the use of three such methods: circular dichroism to isolate the binding of multivalent cations coupled to tertiary assembly, surface plasmon resonance to determine the rates of association and dissociation, and isothermal titration calorimetry to dissect the thermodynamic contributions to RNA assembly events. We pay particular attention to practical aspects of these studies, such as careful preparation of samples with fixed free concentrations of cations in order to avoid errors due to ion depletion effects that are common in RNA systems. Examples of applications from our own work with the hairpin ribozyme are shown. Distinctions among the data handling procedures for the various techniques used and solution conditions encountered are also discussed.

  8. Foreign-Accented Speech Perception Ratings: A Multifactorial Case Study

    ERIC Educational Resources Information Center

    Kraut, Rachel; Wulff, Stefanie

    2013-01-01

    Seventy-eight native English speakers rated the foreign-accented speech (FAS) of 24 international students enrolled in an Intensive English programme at a public university in Texas on degree of accent, comprehensibility and communicative ability. Variables considered to potentially impact listeners' ratings were the sex of the speaker, the first…

  9. A Study of the Predictability of School District Bond Ratings.

    ERIC Educational Resources Information Center

    Vedra, Kenneth David

    School district bond ratings, issued on request by Standard and Poor's Corporation or Moody's Investors Service, hold implications for school districts' financial management. Ultimately, the bond rating assigned is a factor affecting the total cost of the bond issuance, related to the principal and interest payments over the life of the debt. A…

  10. Local Measurement of Fuel Energy Deposition and Heat Transfer Environment During Fuel Lifetime Using Controlled Calorimetry

    SciTech Connect

    Don W. Miller; Andrew Kauffmann; Eric Kreidler; Dongxu Li; Hanying Liu; Daniel Mills; Thomas D. Radcliff; Joseph Talnagi

    2001-12-31

    A comprehensive description of the accomplishments of the DOE grant titled, ''Local Measurement of Fuel Energy Deposition and Heat Transfer Environment During Fuel Lifetime using Controlled Calorimetry''.

  11. Studying biofuel aerosol evaporation rates with single particle manipulation

    NASA Astrophysics Data System (ADS)

    Corsetti, S.; Miles, R. E. H.; Reid, J. P.; Kiefer, J.; McGloin, D.

    2014-09-01

    The significant increase in the air pollution, and the impact on climate change due to the burning of fossil fuel has led to the research of alternative energies. Bio-ethanol obtained from a variety of feedstocks can provide a feasible solution. Mixing bio-ethanol with gasoline leads to a reduction in CO emission and in NOx emissions compared with the use of gasoline alone. However, adding ethanol leads to a change in the fuel evaporation. Here we present a preliminary investigation of evaporation times of single ethanol-gasoline droplets. In particular, we investigated the different evaporation rate of the droplets depending on the variation in the percentage of ethanol inside them. Two different techniques have been used to trap the droplets. One makes use of a 532nm optical tweezers set up, the other of an electrodynamics balance (EDB). The droplets decreasing size was measured using video analysis and elastic light scattering respectively. In the first case measurements were conducted at 293.15 K and ambient humidity. In the second case at 280.5 K and a controlled environment has been preserved by flowing nitrogen into the chamber. Binary phase droplets with a higher percentage of ethanol resulted in longer droplet lifetimes. Our work also highlights the advantages and disadvantages of each technique for such studies. In particular it is challenging to trap droplets with low ethanol content (such as pure gasoline) by the use of EDB. Conversely such droplets are trivial to trap using optical tweezers.

  12. A High-Throughput Biological Calorimetry Core: Steps to Startup, Run, and Maintain a Multiuser Facility.

    PubMed

    Yennawar, Neela H; Fecko, Julia A; Showalter, Scott A; Bevilacqua, Philip C

    2016-01-01

    Many labs have conventional calorimeters where denaturation and binding experiments are setup and run one at a time. While these systems are highly informative to biopolymer folding and ligand interaction, they require considerable manual intervention for cleaning and setup. As such, the throughput for such setups is limited typically to a few runs a day. With a large number of experimental parameters to explore including different buffers, macromolecule concentrations, temperatures, ligands, mutants, controls, replicates, and instrument tests, the need for high-throughput automated calorimeters is on the rise. Lower sample volume requirements and reduced user intervention time compared to the manual instruments have improved turnover of calorimetry experiments in a high-throughput format where 25 or more runs can be conducted per day. The cost and efforts to maintain high-throughput equipment typically demands that these instruments be housed in a multiuser core facility. We describe here the steps taken to successfully start and run an automated biological calorimetry facility at Pennsylvania State University. Scientists from various departments at Penn State including Chemistry, Biochemistry and Molecular Biology, Bioengineering, Biology, Food Science, and Chemical Engineering are benefiting from this core facility. Samples studied include proteins, nucleic acids, sugars, lipids, synthetic polymers, small molecules, natural products, and virus capsids. This facility has led to higher throughput of data, which has been leveraged into grant support, attracting new faculty hire and has led to some exciting publications.

  13. Thermal expansivities of peptides, polypeptides and proteins as measured by pressure perturbation calorimetry.

    PubMed

    Pandharipande, Pranav P; Makhatadze, George I

    2015-04-01

    The main goal of this work was to provide direct experimental evidence that the expansivity of peptides, polypeptides and proteins as measured by pressure perturbation calorimetry (PPC), can serve as a proxy to characterize relative compactness of proteins, especially the denatured state ensemble. This is very important as currently only small angle X-ray scattering (SAXS), intrinsic viscosity and, to a lesser degree, fluorescence resonance transfer (FRET) experiments are capable of reporting on the compactness of denatured state ensembles. We combined the expansivity measurements with other biophysical methods (far-UV circular dichroism spectroscopy, differential scanning calorimetry, and small angle X-ray scattering). Three case studies of the effects of conformational changes on the expansivity of polypeptides in solution are presented. We have shown that expansivity appears to be insensitive to the helix-coil transition, and appears to reflect the changes in hydration of the side-chains. We also observed that the expansivity is sensitive to the global conformation of the polypeptide chain and thus can be potentially used to probe hydration of different collapsed states of denatured or even intrinsically disordered proteins.

  14. Applications of isothermal titration calorimetry in protein science.

    PubMed

    Liang, Yi

    2008-07-01

    During the past decade, isothermal titration calorimetry (ITC) has developed from a specialist method for understanding molecular interactions and other biological processes within cells to a more robust, widely used method. Nowadays, ITC is used to investigate all types of protein interactions, including protein-protein interactions, protein-DNA/RNA interactions, protein-small molecule interactions and enzyme kinetics; it provides a direct route to the complete thermodynamic characterization of protein interactions. This review concentrates on the new applications of ITC in protein folding and misfolding, its traditional application in protein interactions, and an overview of what can be achieved in the field of protein science using this method and what developments are likely to occur in the near future. Also, this review discusses some new developments of ITC method in protein science, such as the reverse titration of ITC and the displacement method of ITC.

  15. Monitoring RNA-ligand interactions using isothermal titration calorimetry.

    PubMed

    Gilbert, Sunny D; Batey, Robert T

    2009-01-01

    Isothermal titration calorimetry (ITC) is a biophysical technique that measures the heat evolved or absorbed during a reaction to report the enthalpy, entropy, stoichiometry of binding, and equilibrium association constant. A significant advantage of ITC over other methods is that it can be readily applied to almost any RNA-ligand complex without having to label either molecule and can be performed under a broad range of pH, temperature, and ionic concentrations. During our application of ITC to investigate the thermodynamic details of the interaction of a variety of compounds with the purine riboswitch, we have explored and optimized experimental parameters that yield the most useful and reproducible results for RNAs. In this chapter, we detail this method using the titration of an adenine-binding RNA with 2,6-diaminopurine (DAP) as a practical example. Our insights should be generally applicable to observing the interactions of a broad range of molecules with structured RNAs.

  16. Studying solutions at high shear rates: a dedicated microfluidics setup.

    PubMed

    Wieland, D C F; Garamus, V M; Zander, T; Krywka, C; Wang, M; Dedinaite, A; Claesson, P M; Willumeit-Römer, R

    2016-03-01

    The development of a dedicated small-angle X-ray scattering setup for the investigation of complex fluids at different controlled shear conditions is reported. The setup utilizes a microfluidics chip with a narrowing channel. As a consequence, a shear gradient is generated within the channel and the effect of shear rate on structure and interactions is mapped spatially. In a first experiment small-angle X-ray scattering is utilized to investigate highly concentrated protein solutions up to a shear rate of 300000 s(-1). These data demonstrate that equilibrium clusters of lysozyme are destabilized at high shear rates.

  17. A comparative study of clock rate and drift estimation

    NASA Technical Reports Server (NTRS)

    Breakiron, Lee A.

    1994-01-01

    Five different methods of drift determination and four different methods of rate determination were compared using months of hourly phase and frequency data from a sample of cesium clocks and active hydrogen masers. Linear least squares on frequency is selected as the optimal method of determining both drift and rate, more on the basis of parameter parsimony and confidence measures than on random and systematic errors.

  18. Optimized robust plasma sampling for glomerular filtration rate studies.

    PubMed

    Murray, Anthony W; Gannon, Mark A; Barnfield, Mark C; Waller, Michael L

    2012-09-01

    In the presence of abnormal fluid collection (e.g. ascites), the measurement of glomerular filtration rate (GFR) based on a small number (1-4) of plasma samples fails. This study investigated how a few samples will allow adequate characterization of plasma clearance to give a robust and accurate GFR measurement. A total of 68 nine-sample GFR tests (from 45 oncology patients) with abnormal clearance of a glomerular tracer were audited to develop a Monte Carlo model. This was used to generate 20 000 synthetic but clinically realistic clearance curves, which were sampled at the 10 time points suggested by the British Nuclear Medicine Society. All combinations comprising between four and 10 samples were then used to estimate the area under the clearance curve by nonlinear regression. The audited clinical plasma curves were all well represented pragmatically as biexponential curves. The area under the curve can be well estimated using as few as five judiciously timed samples (5, 10, 15, 90 and 180 min). Several seven-sample schedules (e.g. 5, 10, 15, 60, 90, 180 and 240 min) are tolerant to any one sample being discounted without significant loss of accuracy or precision. A research tool has been developed that can be used to estimate the accuracy and precision of any pattern of plasma sampling in the presence of 'third-space' kinetics. This could also be used clinically to estimate the accuracy and precision of GFR calculated from mistimed or incomplete sets of samples. It has been used to identify optimized plasma sampling schedules for GFR measurement.

  19. Comparison of steps and energy expenditure assessment in adults of Fitbit Tracker and Ultra to the Actical and indirect calorimetry.

    PubMed

    Adam Noah, J; Spierer, David K; Gu, Jialu; Bronner, Shaw

    2013-10-01

    Epidemic levels of inactivity are associated with chronic diseases and rising healthcare costs. To address this, accelerometers have been used to track levels of activity. The Fitbit and Fitbit Ultra are some of the newest commercially available accelerometers. The purpose of this study was to determine the reliability and validity of the Fitbit and Fitbit Ultra. Twenty-three subjects were fitted with two Fitbit and Fitbit Ultra accelerometers, two industry-standard accelerometers and an indirect calorimetry device. Subjects participated in 6-min bouts of treadmill walking, jogging and stair stepping. Results indicate the Fitbit and Fitbit Ultra are reliable and valid for activity monitoring (step counts) and determining energy expenditure while walking and jogging without an incline. The Fitbit and standard accelerometers under-estimated energy expenditure compared to indirect calorimetry for inclined activities. These data suggest the Fitbit and Fitbit Ultra are reliable and valid for monitoring over-ground energy expenditure.

  20. A unified framework based on the binding polynomial for characterizing biological systems by isothermal titration calorimetry.

    PubMed

    Vega, Sonia; Abian, Olga; Velazquez-Campoy, Adrian

    2015-04-01

    Isothermal titration calorimetry (ITC) has become the gold-standard technique for studying binding processes due to its high precision and sensitivity, as well as its capability for the simultaneous determination of the association equilibrium constant, the binding enthalpy and the binding stoichiometry. The current widespread use of ITC for biological systems has been facilitated by technical advances and the availability of commercial calorimeters. However, the complexity of data analysis for non-standard models is one of the most significant drawbacks in ITC. Many models for studying macromolecular interactions can be found in the literature, but it looks like each biological system requires specific modeling and data analysis approaches. The aim of this article is to solve this lack of unity and provide a unified methodological framework for studying binding interactions by ITC that can be applied to any experimental system. The apparent complexity of this methodology, based on the binding polynomial, is overcome by its easy generalization to complex systems.

  1. Oxygen utilization rate (OUR) underestimates ocean respiration: A model study

    NASA Astrophysics Data System (ADS)

    Koeve, W.; Kähler, P.

    2016-08-01

    We use a simple 1-D model representing an isolated density surface in the ocean and 3-D global ocean biogeochemical models to evaluate the concept of computing the subsurface oceanic oxygen utilization rate (OUR) from the changes of apparent oxygen utilization (AOU) and water age. The distribution of AOU in the ocean is not only the imprint of respiration in the ocean's interior but is strongly influenced by transport processes and eventually loss at the ocean surface. Since AOU and water age are subject to advection and diffusive mixing, it is only when they are affected both in the same way that OUR represents the correct rate of oxygen consumption. This is the case only when advection prevails or with uniform respiration rates, when the proportions of AOU and age are not changed by transport. In experiments with the 1-D tube model, OUR underestimates respiration when maximum respiration rates occur near the outcrops of isopycnals and overestimates when maxima occur far from the outcrops. Given the distribution of respiration in the ocean, i.e., elevated rates near high-latitude outcrops of isopycnals and low rates below the oligotrophic gyres, underestimates are the rule. Integrating these effects globally in three coupled ocean biogeochemical and circulation models, we find that AOU-over-age based calculations underestimate true model respiration by a factor of 3. Most of this difference is observed in the upper 1000 m of the ocean with the discrepancies increasing toward the surface where OUR underestimates respiration by as much as factor of 4.

  2. Field study of variable rate irrigation management in humid climates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil physical properties in the Mississippi Delta can vary considerably within a single field resulting in differing water storage capabilities, amounts of water available to the crop, and crop yield potential. Variable rate irrigation (VRI) technologies are able to site-specifically apply irrigatio...

  3. A comparative study on karyotypic diversification rate in mammals.

    PubMed

    Martinez, P A; Jacobina, U P; Fernandes, R V; Brito, C; Penone, C; Amado, T F; Fonseca, C R; Bidau, C J

    2017-04-01

    Chromosomal rearrangements have a relevant role in organismic evolution. However, little is known about the mechanisms that lead different phylogenetic clades to have different chromosomal rearrangement rates. Here, we investigate the causes behind the wide karyotypic diversity exhibited by mammals. In particular, we analyzed the role of metabolic, reproductive, biogeographic and genomic characteristics on the rates of macro- and microstructural karyotypic diversification (rKD) using comparative phylogenetic methods. We found evidence that reproductive characteristics such as larger litter size per year and longevity, by allowing a higher number of meioses in absolute time, favor a higher probability of chromosomal change. Furthermore, families with large geographic distributions but containing species with restricted geographic ranges showed a greater probability of fixation of macrostructural chromosomal changes in different geographic areas. Finally, rKD does not evolve by Brownian motion because the mutation rate depends on the concerted evolution of repetitive sequences. The decisive factors of rKD evolution will be natural selection, genetic drift and meiotic drive that will eventually allow or not the fixation of the rearrangements. Our results indicate that mammalian karyotypic diversity is influenced by historical and adaptive mechanisms where reproductive and genomic factors modulate the rate of chromosomal change.

  4. A Burning Rate Emulator (BRE) for Study in Microgravity

    NASA Technical Reports Server (NTRS)

    Markan, A.; Sunderland, P. B.; Quintiere, J. G.; DeRis, J.; Stocker, D. P.

    2015-01-01

    A gas-fueled burner, the Burning Rate Emulator (BRE), is used to emulate condensed-phase fuel flames. The design has been validated to easily measure the burning behavior of condensed-phase fuels by igniting a controlled stream of gas fuel and diluent. Four properties, including the heat of combustion, the heat of gasification, the surface temperature, and the laminar smoke point, are assumed to be sufficient to define the steady burning rate of a condensed-phase fuel. The heat of gasification of the fuel is determined by measuring the heat flux and the fuel flow rate. Microgravity BRE tests in the NASA 5.2 s drop facility have examined the burning of pure methane and ethylene (pure and 50 in N2 balance). Fuel flow rates, chamber oxygen concentration and initial pressure have been varied. Two burner sizes, 25 and 50 mm respectively, are chosen to examine the nature of initial microgravity burning. The tests reveal bubble-like flames that increase within the 5.2s drop but the heat flux received from the flame appears to asymptotically approach steady state. Portions of the methane flames appear to locally detach and extinguish at center, while its shape remains fixed, but growing. The effective heat of gasification is computed from the final measured net heat flux and the fuel flow rate under the assumption of an achieved steady burning. Heat flux (or mass flux) and flame position are compared with stagnant layer burning theory. The analysis offers the prospect of more complete findings from future longer duration ISS experiments.

  5. Oxygen consumption rate v. rate of energy utilization of fishes: a comparison and brief history of the two measurements.

    PubMed

    Nelson, J A

    2016-01-01

    Accounting for energy use by fishes has been taking place for over 200 years. The original, and continuing gold standard for measuring energy use in terrestrial animals, is to account for the waste heat produced by all reactions of metabolism, a process referred to as direct calorimetry. Direct calorimetry is not easy or convenient in terrestrial animals and is extremely difficult in aquatic animals. Thus, the original and most subsequent measurements of metabolic activity in fishes have been measured via indirect calorimetry. Indirect calorimetry takes advantage of the fact that oxygen is consumed and carbon dioxide is produced during the catabolic conversion of foodstuffs or energy reserves to useful ATP energy. As measuring [CO2 ] in water is more challenging than measuring [O2 ], most indirect calorimetric studies on fishes have used the rate of O2 consumption. To relate measurements of O2 consumption back to actual energy usage requires knowledge of the substrate being oxidized. Many contemporary studies of O2 consumption by fishes do not attempt to relate this measurement back to actual energy usage. Thus, the rate of oxygen consumption (M˙O2 ) has become a measurement in its own right that is not necessarily synonymous with metabolic rate. Because all extant fishes are obligate aerobes (many fishes engage in substantial net anaerobiosis, but all require oxygen to complete their life cycle), this discrepancy does not appear to be of great concern to the fish biology community, and reports of fish oxygen consumption, without being related to energy, have proliferated. Unfortunately, under some circumstances, these measures can be quite different from one another. A review of the methodological history of the two measurements and a look towards the future are included.

  6. Low-temperature polymorphic phase transition in a crystalline tripeptide L-Ala-L-Pro-Gly·H2O revealed by adiabatic calorimetry.

    PubMed

    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.

  7. Exploring the binding mechanism of phosphoramidate derivative with DNA: Spectroscopy, calorimetry and modeling

    NASA Astrophysics Data System (ADS)

    Wang, Gongke; Wu, Hongwei; Wang, Dongchao; Yan, Changling; Lu, Yan

    2013-03-01

    In this study, one of the amino phosphine ester derivatives α-(3-hydroxy-4-methoxyphenyl)-N-phenyl-α-aminophosphonate (HMPAP) was synthesized, and the molecular interaction of HMPAP with ct-DNA has been investigated by UV-Vis absorption spectra, fluorescence spectra, isothermal titration calorimetry (ITC) and molecular modeling. The binding constant (Kb) of HMPAP to ct-DNA at different temperatures were calculated from fluorescence spectra. According to the UV-Vis absorption spectra, ethidium bromide displacement studies and ITC experimental results, we can conclude that HMPAP is an intercalator. The molecular modeling results indicated that HMPAP can slide into the G-C rich region of ct-DNA. ITC data showed that ct-DNA/HMPAP binding is enthalpy controlled. Furthermore, the results obtained from molecular modeling corroborated the experimental results obtanied from spectroscopic and ITC investigations.

  8. Low resistance bakelite RPC study for high rate working capability

    DOE PAGES

    Dai, T.; Han, L.; Hou, S.; ...

    2014-11-19

    This paper presents series efforts to lower resistance of bakelite electrode plate to improve the RPC capability under high rate working condition. New bakelite material with alkali metallic ion doping has been manufactured and tested. This bakelite is found unstable under large charge flux and need further investigation. A new structure of carbon-embedded bakelite RPC has been developed, which can reduce the effective resistance of electrode by a factor of 10. The prototype of the carbon-embedded chamber could function well under gamma radiation source at event rate higher than 10 kHz/cm2. The preliminary tests show that this kind of newmore » structure performs as efficiently as traditional RPCs.« less

  9. Low resistance bakelite RPC study for high rate working capability

    SciTech Connect

    Dai, T.; Han, L.; Hou, S.; Liu, M.; Li, Q.; Song, H.; Xia, L.; Zhang, Z.

    2014-11-19

    This paper presents series efforts to lower resistance of bakelite electrode plate to improve the RPC capability under high rate working condition. New bakelite material with alkali metallic ion doping has been manufactured and tested. This bakelite is found unstable under large charge flux and need further investigation. A new structure of carbon-embedded bakelite RPC has been developed, which can reduce the effective resistance of electrode by a factor of 10. The prototype of the carbon-embedded chamber could function well under gamma radiation source at event rate higher than 10 kHz/cm2. The preliminary tests show that this kind of new structure performs as efficiently as traditional RPCs.

  10. High-pressure burning rate studies of solid rocket propellants

    NASA Astrophysics Data System (ADS)

    Atwood, A. I.; Ford, K. P.; Wheeler, C. J.

    2013-03-01

    Increased rocket motor performance is a major driver in the development of solid rocket propellant formulations for chemical propulsion systems. The use of increased operating pressure is an option to improve performance potentially without the cost of reformulation. A technique has been developed to obtain burning rate data across a range of pressures from ambient to 345 MPa. The technique combines the use of a low loading density combustion bomb with a high loading density closed bomb technique. A series of nine ammonium perchlorate (AP) based propellants were used to demonstrate the use of the technique, and the results were compared to the neat AP burning rate "barrier". The effect of plasticizer, oxidizer particle size, catalyst, and binder type were investigated.

  11. Burning Rate Studies of HMX Propellants at High Pressures

    DTIC Science & Technology

    1975-03-01

    propellant burning should take place rather than HMX burning. The compounds selected for evaluation were: Melting Point Boiling Point (0C) (0 C) acetanilide ... Acetanilide and phenylsulfone, the two very la,, melting cxnpounds, greatly suppressed the KV exotherm peak (rigue 3). However, this change in the TV...Percent IM (Class A/E, 70/30), 2 Percent Additive] Phenyl Hydro- Additive None Acetanilide Anthracene Sulfone Quinone Pressure (Psi) Burning Rate @ 70

  12. Fluorescence spectroscopic and calorimetry based approaches to characterize the mode of interaction of small molecules with DNA.

    PubMed

    Banerjee, Amrita; Singh, Jasdeep; Dasgupta, Dipak

    2013-07-01

    Ethidium bromide displacement assay by fluorescence is frequently used as a diagnostic tool to identify the intercalation ability of DNA binding small molecules. Here we have demonstrated that the method has pitfalls. We have employed fluorescence, absorbance and label free technique such as isothermal titration calorimetry to probe the limitations. Ethidium bromide, a non-specific intercalator, netropsin, a (A-T) specific minor groove binder, and sanguinarine, a (G-C) specific intercalator, have been used in our experiments to study the association of a ligand with DNA in presence of a competing ligand. Here we have shown that netropsin quenches the fluorescence intensity of an equilibrium mixture of ethidium bromide - calf thymus DNA via displacement of ethidium bromide. Isothermal titration calorimetry results question the accepted interpretation of the observed decrease in fluorescence of bound ethidium bromide in terms of competitive binding of two ligands to DNA. Furthermore, isothermal titration calorimetry experiments and absorbance measurements indicate that the fluorescence change might be due to formation of ternary complex and not displacement of one ligand by another.

  13. Proton Calorimetry and Gamma-Rays in Arp 220

    NASA Astrophysics Data System (ADS)

    Yoast-Hull, Tova; Gallagher, John S.; Zweibel, Ellen Gould

    2014-08-01

    Until recently, it was thought that starburst galaxies were both electron and proton calorimeters, making them especially bright in gamma-rays. However, with detections of starburst galaxies M82 and NGC 253 by Fermi, HESS, and VERITAS, we find that such galaxies are only partial proton calorimeters due to significant advection by galactic winds. Thus, to find cosmic-ray proton calorimeters, we must look for much denser systems. Previous models of the cosmic ray interactions in Arp 220 (e.g. Torres 2004) suggest it is a proton calorimeter and that it should already be detectable by Fermi. The Torres model suggests that if Arp 220 is a calorimeter, then it should have been detected in gamma-rays by Fermi at levels above current upper limits. We therefore must question. whether Arp 220 is a true proton calorimeter, and if so what other properties could be responsible for its low gamma ray flux. Here, we further explore the observed ranges on environmental properties and model the central nuclei to predict both the radio and gamma-ray spectra. We test the proton calorimetry hypothesis and estimate the observation time needed for a detection by Fermi for a range of assumptions about conditions in Arp 220.

  14. Statistical analysis of plasma thermograms measured by differential scanning calorimetry.

    PubMed

    Fish, Daniel J; Brewood, Greg P; Kim, Jong Sung; Garbett, Nichola C; Chaires, Jonathan B; Benight, Albert S

    2010-11-01

    Melting curves of human plasma measured by differential scanning calorimetry (DSC), known as thermograms, have the potential to markedly impact diagnosis of human diseases. A general statistical methodology is developed to analyze and classify DSC thermograms to analyze and classify thermograms. Analysis of an acquired thermogram involves comparison with a database of empirical reference thermograms from clinically characterized diseases. Two parameters, a distance metric, P, and correlation coefficient, r, are combined to produce a 'similarity metric,' ρ, which can be used to classify unknown thermograms into pre-characterized categories. Simulated thermograms known to lie within or fall outside of the 90% quantile range around a median reference are also analyzed. Results verify the utility of the methods and establish the apparent dynamic range of the metric ρ. Methods are then applied to data obtained from a collection of plasma samples from patients clinically diagnosed with SLE (lupus). High correspondence is found between curve shapes and values of the metric ρ. In a final application, an elementary classification rule is implemented to successfully analyze and classify unlabeled thermograms. These methods constitute a set of powerful yet easy to implement tools for quantitative classification, analysis and interpretation of DSC plasma melting curves.

  15. Application of pressure perturbation calorimetry to lipid bilayers.

    PubMed

    Heerklotz, Heiko; Seelig, Joachim

    2002-03-01

    Pressure perturbation calorimetry (PPC) is a new method that measures the heat consumed or released by a sample after a sudden pressure jump. The heat change can be used to derive the thermal volume expansion coefficient, alpha(V), as a function of temperature and, in the case of phase transitions, the volume change, DeltaV, occurring at the phase transition. Here we present the first report on the application of PPC to determine these quantities for lipid bilayers. We measure the volume changes of the pretransition and main transition of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), and the thermal expansivity of the fluid phase of DMPC and of two unsaturated lipids, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine and 1,2-dioleoyl-sn-glycero-3-phosphocholine. The high sensitivity of PPC instrumentation gives accurate data for alpha(V) and DeltaV even upon the application of relatively low pressures of approximately 5 bar.

  16. Application of isothermal titration calorimetry in bioinorganic chemistry.

    PubMed

    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.

  17. Applying fast calorimetry on a spent nuclear fuel calorimeter

    SciTech Connect

    Liljenfeldt, Henrik

    2015-04-15

    Recently at Los Alamos National Laboratory, sophisticated prediction algorithms have been considered for the use of calorimetry for treaty verification. These algorithms aim to predict the equilibrium temperature based on early data and therefore be able to shorten the measurement time while maintaining good accuracy. The algorithms have been implemented in MATLAB and applied on existing equilibrium measurements from a spent nuclear fuel calorimeter located at the Swedish nuclear fuel interim storage facility. The results show significant improvements in measurement time in the order of 15 to 50 compared to equilibrium measurements, but cannot predict the heat accurately in less time than the currently used temperature increase method can. This Is both due to uncertainties in the calibration of the method as well as identified design features of the calorimeter that limits the usefulness of equilibrium type measurements. The conclusions of these findings are discussed, and suggestions of both improvements of the current calorimeter as well as what to keep in mind in a new design are given.

  18. Characterization of protein-protein interactions by isothermal titration calorimetry.

    PubMed

    Velazquez-Campoy, Adrian; Leavitt, Stephanie A; Freire, Ernesto

    2015-01-01

    The analysis of protein-protein interactions has attracted the attention of many researchers from both a fundamental point of view and a practical point of view. From a fundamental point of view, the development of an understanding of the signaling events triggered by the interaction of two or more proteins provides key information to elucidate the functioning of many cell processes. From a practical point of view, understanding protein-protein interactions at a quantitative level provides the foundation for the development of antagonists or agonists of those interactions. Isothermal Titration Calorimetry (ITC) is the only technique with the capability of measuring not only binding affinity but the enthalpic and entropic components that define affinity. Over the years, isothermal titration calorimeters have evolved in sensitivity and accuracy. Today, TA Instruments and MicroCal market instruments with the performance required to evaluate protein-protein interactions. In this methods paper, we describe general procedures to analyze heterodimeric (porcine pancreatic trypsin binding to soybean trypsin inhibitor) and homodimeric (bovine pancreatic α-chymotrypsin) protein associations by ITC.

  19. A microfabrication-based approach to quantitative isothermal titration calorimetry.

    PubMed

    Wang, Bin; Jia, Yuan; Lin, Qiao

    2016-04-15

    Isothermal titration calorimetry (ITC) directly measures heat evolved in a chemical reaction to determine equilibrium binding properties of biomolecular systems. Conventional ITC instruments are expensive, use complicated design and construction, and require long analysis times. Microfabricated calorimetric devices are promising, although they have yet to allow accurate, quantitative ITC measurements of biochemical reactions. This paper presents a microfabrication-based approach to integrated, quantitative ITC characterization of biomolecular interactions. The approach integrates microfabricated differential calorimetric sensors with microfluidic titration. Biomolecules and reagents are introduced at each of a series of molar ratios, mixed, and allowed to react. The reaction thermal power is differentially measured, and used to determine the thermodynamic profile of the biomolecular interactions. Implemented in a microdevice featuring thermally isolated, well-defined reaction volumes with minimized fluid evaporation as well as highly sensitive thermoelectric sensing, the approach enables accurate and quantitative ITC measurements of protein-ligand interactions under different isothermal conditions. Using the approach, we demonstrate ITC characterization of the binding of 18-Crown-6 with barium chloride, and the binding of ribonuclease A with cytidine 2'-monophosphate within reaction volumes of approximately 0.7 µL and at concentrations down to 2mM. For each binding system, the ITC measurements were completed with considerably reduced analysis times and material consumption, and yielded a complete thermodynamic profile of the molecular interaction in agreement with published data. This demonstrates the potential usefulness of our approach for biomolecular characterization in biomedical applications.

  20. Advantages of isothermal titration calorimetry for xylanase kinetics in comparison to chemical-reducing-end assays.

    PubMed

    Baumann, Martin J; Murphy, Leigh; Lei, Nina; Krogh, Kristian B R M; Borch, Kim; Westh, Peter

    2011-03-01

    In lignocellulosic raw materials for biomass conversion, hemicelluloses constitute a substantial fraction, with xylan being the primary part. Although many pretreatments reduce the amount or change the distribution of xylan, it is important to degrade residual xylan so as to improve the overall yield. Typically, xylanase reaction rates are measured in stopped assays by chemical quantification of the reducing ends. With isothermal titration calorimetry (ITC), the heat flow of the hydrolysis can be measured in continuous fashion, with the reaction rate being directly proportional to the heat flow. Reaction enthalpies for carbohydrate hydrolysis are typically below 5kJ/mol, which is the limiting factor for straight forward calorimetric quantification of enzymatic reaction rates using current ITC technology. To increase the apparent reaction enthalpy, we employed a subsequent oxidation of hydrolysis products by carbohydrate oxidase and catalase. Here we show that the coupled assay with carbohydrate oxidase and catalase can be used to measure enzyme kinetics of a GH10 xylanase from Aspergillus aculeatus on birch xylan and wheat arabinoxylan. Results are discussed in the light of a critical analysis of the sensitivity of four chemical-reducing-end quantification methods using well-characterized substrates.

  1. 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.

  2. Probing the binding of (+)-catechin to bovine serum albumin by isothermal titration calorimetry and spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Li, Xiangrong; Hao, Yongbing

    2015-07-01

    In this study, the interaction between (+)-catechin and bovine serum albumin (BSA) was investigated using isothermal titration calorimetry (ITC), in combination with fluorescence spectroscopy, UV-vis absorption spectroscopy, and Fourier transform infrared (FT-IR) spectroscopy. Thermodynamic investigations reveal that the electrostatic interaction and hydrophobic interaction are the major binding forces in the binding of (+)-catechin to BSA. The binding of (+)-catechin to BSA is synergistically driven by enthalpy and entropy. Fluorescence experiments suggest that (+)-catechin can quench the fluorescence of BSA through a static quenching mechanism. The obtained binding constants and the equilibrium fraction of unbound (+)-catechin show that (+)-catechin can be stored and transported from the circulatory system to reach its target organ. Binding site I is found to be the primary binding site for (+)-catechin. Additionally, as shown by the UV-vis absorption, synchronous fluorescence spectroscopy and FT-IR, (+)-catechin may induce conformational and microenvironmental changes of BSA.

  3. Differential scanning calorimetry of blood plasma for clinical diagnosis and monitoring.

    PubMed

    Garbett, Nichola C; Mekmaysy, Chongkham S; Helm, C William; Jenson, A Bennett; Chaires, Jonathan B

    2009-06-01

    Differential scanning calorimetry (DSC) provides a useful method to study the unfractionated plasma proteome. Plasma from healthy individuals yields a reproducible signature thermogram which results from the weighted sum of the thermal denaturation of the most abundant plasma proteins. Further investigation of the thermogram for healthy individuals showed it to be sensitive to ethnicity and gender. DSC analysis of plasma from diseased individuals revealed significant changes in the thermogram which are suggested to result not from changes in the concentration of the major plasma proteins but from interactions of small molecules or peptides with these proteins. Closer examination of the diseased thermograms showed a thermogram characteristic of each disease. For cervical cancer, the DSC method yields a progressively shifted thermogram as the disease advances from pre-invasive conditions to late stage cancer. Our application of the DSC method has provided a potential tool for the early diagnosis, monitoring and screening of cancer patients.

  4. Probing the thermodynamics of protein-lipid interactions by isothermal titration calorimetry.

    PubMed

    Swamy, Musti J; Sankhala, Rajeshwer S

    2013-01-01

    Isothermal titration calorimetry is a highly sensitive technique for the study of molecular interactions. This method has been applied quite extensively to investigate the interaction of proteins with small ligands, other proteins, and nucleic acids as well as with drugs and metal ions. In this chapter, we describe the application of ITC for the investigation of thermodynamics of protein-lipid interaction. A number of parameters such as enthalpy of binding (ΔH), entropy of binding (ΔS), association constant (K (a)), binding stoichiometry (n), and free energy of binding (ΔG) can be obtained from a single calorimetric titration, providing a complete thermodynamic characterization of the interaction. The method is described in detail taking the major protein of the bovine seminal plasma, PDC-109, which exhibits a high preference for interaction with choline-containing lipids, as an example. The method can be applied to investigate the thermodynamics of the interaction of other soluble proteins with lipid membranes.

  5. The Frontier of Modern Calorimetry: Hardware Advances and Application in Particle Physics Analysis

    NASA Astrophysics Data System (ADS)

    Medvedeva, Tatiana

    While the last missing components of the SM puzzle seem to be successfully found, particle physicists remain hungry for what might be there, beyond the cosy boundaries of the well studies elementary particle world. However, the sophisticated technique of data analysis and acute Monte Carlo simulations remain fruitless. It appears that the successful intrusion into the realm, in which we were not welcome so far, may require a very different implication of effort. All those results might suggest, though banal, that we need an improvement on the hardware side. Indeed, the hadronic calorimeter of CMS is no competitor to its other state-of-art components. This obstacle in many cases significantly complicates the flow of the physics analysis. Besides, the era of high luminosity LHC operation in the offing is calling for the same. After exploration of the analysis debri with 8TeV collision data, we investigate various approaches for better calorimetry for the CMS detector.

  6. Study of bit error rate (BER) for multicarrier OFDM

    NASA Astrophysics Data System (ADS)

    Alshammari, Ahmed; Albdran, Saleh; Matin, Mohammad

    2012-10-01

    Orthogonal Frequency Division Multiplexing (OFDM) is a multicarrier technique that is being used more and more in recent wideband digital communications. It is known for its ability to handle severe channel conditions, the efficiency of spectral usage and the high data rate. Therefore, It has been used in many wired and wireless communication systems such as DSL, wireless networks and 4G mobile communications. Data streams are modulated and sent over multiple subcarriers using either M-QAM or M-PSK. OFDM has lower inter simple interference (ISI) levels because of the of the low data rates of carriers resulting in long symbol periods. In this paper, BER performance of OFDM with respect to signal to noise ratio (SNR) is evaluated. BPSK Modulation is used in s Simulation based system in order to get the BER over different wireless channels. These channels include additive white Gaussian Noise (AWGN) and fading channels that are based on Doppler spread and Delay spread. Plots of the results are compared with each other after varying some of the key parameters of the system such as the IFFT, number of carriers, SNR. The results of the simulation give visualization of what kind of BER to expect when the signal goes through those channels.

  7. Pilot Validation Study: Canadian Global Rating Scale for Colonoscopy Services

    PubMed Central

    El Ouali, Sara

    2016-01-01

    Background. The United Kingdom Global Rating Scale (GRS-UK) measures unit-level quality metrics processes in digestive endoscopy. We evaluated the psychometric properties of its Canadian version (GRS-C), endorsed by the Canadian Association of Gastroenterology (CAG). Methods. Prospective data collection at three Canadian endoscopy units assessed GRS-C validity, reliability, and responsiveness to change according to responses provided by physicians, endoscopy nurses, and administrative personnel. These responses were compared to national CAG endoscopic quality guidelines and GRS-UK statements. Results. Most respondents identified the overarching theme each GRS-C item targeted, confirming face validity. Content validity was suggested as 18 out of 23 key CAG endoscopic quality indicators (78%, 95% CI: 56–93%) were addressed in the GRS-C; statements not included pertained to educational programs and competency monitoring. Concordance ranged 75–100% comparing GRS-C and GRS-UK ratings. Test-retest reliability Kappa scores ranged 0.60–0.83, while responsiveness to change scores at 6 months after intervention implementations were greater (P < 0.001) in two out of three units. Conclusion. The GRS-C exhibits satisfactory metrics, supporting its use in a national quality initiative aimed at improving processes in endoscopy units. Data collection from more units and linking to actual patient outcomes are required to ensure that GRS-C implementation facilitates improved patient care. PMID:27840810

  8. [A study to lower the expulsion rate of IUDs].

    PubMed

    Wang, J G

    1983-08-01

    The author has been investigating why the shape and size of the IUD must be suitable to the geometric size and shape of the endometrial cavity. Women vary greatly in the shape and size of the endometrial cavity. When any woman needs to use an IUD, one should measure the transverse as well as the longitudinal diameter of the endometrial cavity at the fundus. One cannot simply depend on the longitudinal length of the vertical axis of the endometrial cavity in choosing the diameter of the ring. The author always uses the uterine metrology device of the GCH-I types to select the diameter of the ring. 1561 women who were wearing IUDs were measured and the probe was used to measure the vertical axis of the endometrial cavity for 1355 women. The women were followed for 3 years. The rate of expulsion of IUDs in the former was 3.9%, and in the latter 6.0. Particularly, the rate of removal in the former because of disease was much lower. There was a marked difference between the two.

  9. Molecular dynamics and reaction kinetics during polymerization using dielectric spectroscopy and calorimetry

    NASA Astrophysics Data System (ADS)

    Wasylyshyn, Dwayne Andrew

    The evolution of molecular dynamics during the polymerization of linear-chain and network forming liquids was studied using dielectric spectroscopy and differential scanning calorimetry. Polymerization was carried out using step-addition reactions between epoxide and amine molecules, and by catalysis of epoxide molecules with tertiary amines. The former resulted in linear-chain or network structured polymers while the latter resulted in network polymers. The step-addition polymerizations resulted in linear-chain polymers by reacting stoichiometric quantities of diepoxide and monoamine molecules, and network structure polymers by reacting stoichiometric quantities of triepoxide and monoamine molecules, or diepoxide and diamine molecules. The growth and extinction of localized (or secondary) relaxation processes during the polymerization were studied by measuring the changing dielectric properties using two techniques; fixed frequency dielectric measurements during heating of the partially polymerized samples, and isothermal dielectric measurements over the frequency range of 1 MHz to 20 GHz. The number of covalent bonds formed at any instant during the polymerization was determined by isothermal calorimetric measurements. Thus, the change in the dielectric properties during polymerization was associated with the increase in the number of covalent bonds. It was found that the localized relaxations evolve in a manner that is independent of the spontaneous increase in configurational entropy. The results also tend evidence towards the concept that these relaxations occur in regions of relatively high energy, and the collapse of such regions led to the observed changes in the dielectric properties. As well, an analogy was made between the structural relaxation of a physically metastable glass and the polymerization of a chemically metastable liquid. This has lead to the concept of a chemical fictive temperature to describe the state of the polymerizing liquid. The

  10. Excitation rate and background measurements during LIF studies on krypton

    NASA Astrophysics Data System (ADS)

    Whitehead, C. A.; Cannon, B. D.; Wacker, J. F.

    1993-04-01

    The Krypton Isotope Laser Analysis (KILA) method is being developed at the Pacific Northwest Laboratory (PNL) to measure Kr-85 concentrations in small air samples. The technique uses high-resolution lasers to excite individual isotopes of krypton specifically to induce Kr-85 to fluorescence for detection by optical means. Production of krypton metastables via two-photon excitation to the 2p(sub 6) state has been shown to be 0.15% efficient in 0.13 mTorr of krypton--sufficiently high to demonstrate overall feasibility of the KILA method. Since this goal was met, focus has been directed toward development of a working vacuum ultraviolet (VUV) fluorescence detection system and toward understanding the VUV background. This report describes the progress made in these two areas. The second step of the KILA process is to optically pump all except the Kr-85 isotopes from the metastable state back to the ground state using laser-induced fluorescence (LIF). The rate of this process and the VUV background afterward will determine the sensitivity and selectivity of the KILA approach. De-excitation of the metastable population was accomplished via one-photon absorption of a continuous-wave (c-w) laser to the 2p(sub 8) energy level. Non-isotopically selective de-excitation rates as high as 5 x 10(exp 5)/sec have been measured, yielding a signal-to-background ratio of g reater than 10(exp 6). The lifetime of the metastables is 1.2 msec in 200 mTorr of neon--much longer than the time required to de-excite krypton metastables and to detect fluorescence produced by Kr-85. After attaining these high de-excitation rates, a gated VUV detection system was built with a dynamic range large enough to measure a small background following de-excitation of large metastable populations. Future experiments will focus on reducing the background level by another 2-3 orders of magnitude and perfecting the isotopically selective de-excitation technique with known samples.

  11. Excitation rate and background measurements during LIF studies on krypton

    SciTech Connect

    Whitehead, C.A.; Cannon, B.D.; Wacker, J.F.

    1993-04-01

    The Krypton Isotope Laser Analysis (KILA) method is being developed at the Pacific Northwest Laboratory (PNL) to measure [sup 85]Kr concentrations in small air samples. The technique uses high-resolution lasers to excite individual isotopes of krypton specifically to induce [sup 85]Kr to fluorescence for detection by optical means. Production of krypton metastables via two-photon excitation to the 2p[sub 6] state has been shown to be 0.15% efficient in 0.13 mTorr of krypton--sufficiently high to demonstrate overall feasibility of the KILA method. Since this goal was met, focus has been directed toward development of a working vacuum ultraviolet (VUV) fluorescence detection system and toward understanding the VUV background. This report describes the progress made in these two areas. The second step of the KILA process is to optically pump all except the [sup 85]Kr isotopes from the metastable state back to the ground state using laser-induced fluorescence (LIF). The rate of this process and the VUV background afterward will determine the sensitivity and selectivity of the KILA approach. De-excitation of the metastable population was accomplished via one-photon absorption of a continuous-wave (c-w) laser to the 2p[sub 8] energy level. Non-isotopically selective de-excitation rates as high as 5 [times] 10[sup 5] sec[sup [minus]1] have been measured, yielding a signal-to-background ratio of >10[sup 6]. The lifetime of the metastables is 1.2 msec in 200 mTorr of neon--much longer than the time required to de-excite krypton metastables and to detect fluorescence produced by [sup 85]Kr. After attaining these high de-excitation rates, a gated VUV detection system was built with a dynamic range large enough to measure a small background following de-excitation of large metastable populations. Future experiments will focus on reducing the background level by another 2--3 orders of magnitude and perfecting the isotopically selective de-excitation technique with known samples.

  12. Excitation rate and background measurements during LIF studies on krypton

    SciTech Connect

    Whitehead, C.A.; Cannon, B.D.; Wacker, J.F.

    1993-04-01

    The Krypton Isotope Laser Analysis (KILA) method is being developed at the Pacific Northwest Laboratory (PNL) to measure {sup 85}Kr concentrations in small air samples. The technique uses high-resolution lasers to excite individual isotopes of krypton specifically to induce {sup 85}Kr to fluorescence for detection by optical means. Production of krypton metastables via two-photon excitation to the 2p{sub 6} state has been shown to be 0.15% efficient in 0.13 mTorr of krypton--sufficiently high to demonstrate overall feasibility of the KILA method. Since this goal was met, focus has been directed toward development of a working vacuum ultraviolet (VUV) fluorescence detection system and toward understanding the VUV background. This report describes the progress made in these two areas. The second step of the KILA process is to optically pump all except the {sup 85}Kr isotopes from the metastable state back to the ground state using laser-induced fluorescence (LIF). The rate of this process and the VUV background afterward will determine the sensitivity and selectivity of the KILA approach. De-excitation of the metastable population was accomplished via one-photon absorption of a continuous-wave (c-w) laser to the 2p{sub 8} energy level. Non-isotopically selective de-excitation rates as high as 5 {times} 10{sup 5} sec{sup {minus}1} have been measured, yielding a signal-to-background ratio of >10{sup 6}. The lifetime of the metastables is 1.2 msec in 200 mTorr of neon--much longer than the time required to de-excite krypton metastables and to detect fluorescence produced by {sup 85}Kr. After attaining these high de-excitation rates, a gated VUV detection system was built with a dynamic range large enough to measure a small background following de-excitation of large metastable populations. Future experiments will focus on reducing the background level by another 2--3 orders of magnitude and perfecting the isotopically selective de-excitation technique with known samples.

  13. Study of etching rate uniformity in SRF cavities

    SciTech Connect

    Janardan Upadhyay, Svetozar Popovic, Leposova Vuskovic, H. Phillips, Anne-Marie Valente

    2012-07-01

    Plasma based surface modification is a promising alternative to wet etching of superconducting radio frequency (SRF) cavities. The crucial aspect of the technology development is dependence of the etching rate and surface roughness on the frequency of the power supply, pressure, power level, driven electrode shape and chlorine concentration in the gas mixture during plasma processing. To optimize the plasma parameters, we are using a single cell cavity with 20 sample holders symmetrically distributed over the cell. These holders are used as diagnostic ports for the measurement of the plasma parameters and as holders for the samples to be etched. The plasma properties are highly correlated with the shape of the driven electrode and chlorine concentration in the Argon/Chlorine gas mixtures.

  14. Efficient Isothermal Titration Calorimetry Technique Identifies Direct Interaction of Small Molecule Inhibitors with the Target Protein.

    PubMed

    Gal, Maayan; Bloch, Itai; Shechter, Nelia; Romanenko, Olga; Shir, Ofer M

    2016-01-01

    Protein-protein interactions (PPI) play a critical role in regulating many cellular processes. Finding novel PPI inhibitors that interfere with specific binding of two proteins is considered a great challenge, mainly due to the complexity involved in characterizing multi-molecular systems and limited understanding of the physical principles governing PPIs. Here we show that the combination of virtual screening techniques, which are capable of filtering a large library of potential small molecule inhibitors, and a unique secondary screening by isothermal titration calorimetry, a label-free method capable of observing direct interactions, is an efficient tool for finding such an inhibitor. In this study we applied this strategy in a search for a small molecule capable of interfering with the interaction of the tumor-suppressor p53 and the E3-ligase MDM2. We virtually screened a library of 15 million small molecules that were filtered to a final set of 80 virtual hits. Our in vitro experimental assay, designed to validate the activity of mixtures of compounds by isothermal titration calorimetry, was used to identify an active molecule against MDM2. At the end of the process the small molecule (4S,7R)-4-(4-chlorophenyl)-5-hydroxy-2,7-dimethyl-N-(6-methylpyridin-2-yl)-4,6,7,8 tetrahydrIoquinoline-3-carboxamide was found to bind MDM2 with a dissociation constant of ~2 µM. Following the identification of this single bioactive compound, spectroscopic measurements were used to further characterize the interaction of the small molecule with the target protein. 2D NMR spectroscopy was used to map the binding region of the small molecule, and fluorescence polarization measurement confirmed that it indeed competes with p53.

  15. Age, growth rates, and paleoclimate studies of deep sea corals

    USGS Publications Warehouse

    Prouty, Nancy G; Roark, E. Brendan; Andrews, Allen; Robinson, Laura; Hill, Tessa; Sherwood, Owen; Williams, Branwen; Guilderson, Thomas P.; Fallon, Stewart

    2015-01-01

    Deep-water corals are some of the slowest growing, longest-lived skeletal accreting marine organisms. These habitat-forming species support diverse faunal assemblages that include commercially and ecologically important organisms. Therefore, effective management and conservation strategies for deep-sea corals can be informed by precise and accurate age, growth rate, and lifespan characteristics for proper assessment of vulnerability and recovery from perturbations. This is especially true for the small number of commercially valuable, and potentially endangered, species that are part of the black and precious coral fisheries (Tsounis et al. 2010). In addition to evaluating time scales of recovery from disturbance or exploitation, accurate age and growth estimates are essential for understanding the life history and ecology of these habitat-forming corals. Given that longevity is a key factor for population maintenance and fishery sustainability, partly due to limited and complex genetic flow among coral populations separated by great distances, accurate age structure for these deep-sea coral communities is essential for proper, long-term resource management.

  16. Dosimetric Study of a Low-Dose-Rate Brachytherapy Source

    NASA Astrophysics Data System (ADS)

    Rodríguez-Villafuerte, M.; Arzamendi, S.; Díaz-Perches, R.

    Carcinoma of the cervix is the most common malignancy - in terms of both incidence and mortality - in Mexican women. Low dose rate (LDR) intracavitary brachytherapy is normally prescribed for the treatment of this disease to the vast majority of patients attending public hospitals in our country. However, most treatment planning systems being used in these hospitals still rely on Sievert integral dose calculations. Moreover, experimental verification of dose distributions are hardly ever done. In this work we present a dosimetric characterisation of the Amersham CDCS-J 137Cs source, an LDR brachytherapy source commonly used in Mexican hospitals. To this end a Monte Carlo simulation was developed, that includes a realistic description of the internal structure of the source embedded in a scattering medium. The Monte Carlo results were compared to experimental measurements of dose distributions. A lucite phantom with the same geometric characteristics as the one used in the simulation was built. Dose measurements were performed using thermoluminescent dosimeters together with commercial RadioChromic dye film. A comparison between our Monte Carlo simulation, the experimental data, and results reported in the literature is presented.

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

    PubMed

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

    2016-09-15

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

  18. The Effect of a Study Skills Workshop on the Attrition Rate in a Practical Nursing Program.

    ERIC Educational Resources Information Center

    Granger, Donna Jean

    A study examined the attrition rate in the Wichita Practical Nursing School in Wichita, Kansas, and the effectiveness of a study skills workshop in reducing the attrition rate. Using a quasi-experimental control group design, the researcher studied the attrition rates of three consecutive classes at the school. The first two classes served as…

  19. Accurate label-free reaction kinetics determination using initial rate heat measurements

    PubMed Central

    Ebrahimi, Kourosh Honarmand; Hagedoorn, Peter-Leon; Jacobs, Denise; Hagen, Wilfred R.

    2015-01-01

    Accurate label-free methods or assays to obtain the initial reaction rates have significant importance in fundamental studies of enzymes and in application-oriented high throughput screening of enzyme activity. Here we introduce a label-free approach for obtaining initial rates of enzyme activity from heat measurements, which we name initial rate calorimetry (IrCal). This approach is based on our new finding that the data recorded by isothermal titration calorimetry for the early stages of a reaction, which have been widely ignored, are correlated to the initial rates. Application of the IrCal approach to various enzymes led to accurate enzyme kinetics parameters as compared to spectroscopic methods and enabled enzyme kinetic studies with natural substrate, e.g. proteases with protein substrates. Because heat is a label-free property of almost all reactions, the IrCal approach holds promise in fundamental studies of various enzymes and in use of calorimetry for high throughput screening of enzyme activity. PMID:26574737

  20. SU-E-T-267: Development of the Compact Graphite Calorimetry System for the High Energy Photon Beam

    SciTech Connect

    Kim, B. C.; Kim, I. J.; Kim, J. H.; Yi, C. Y.

    2015-06-15

    Purpose: Graphite calorimeter systems are used for the absolute photon dosimetry. But many electronics are demanded in order to measure the tiny temperature changes. Minimizing the control system is needed to make a portable graphite calorimeter. Methods: A Domen-type graphite calorimetry system is constructing to measure the absorbed dose of the high energy photon beam. The graphite calorimeter divided into three parts, Core, Jacket, and Shield. In order to measure the temperature rising of the core due to the radiation accurately, the temperatures of the jacket and the shield should be controlled properly. A commercial temperature controller (Model 350, Lake Shore Cryogenics) was used to minimize the size of control system for making a portable graphite calorimetry system at the cost of the measurement uncertainty. The PID control of the jacket is conducted by the software (LabView) and Model 350 maintain the temperature of shield. Results: Our design value of the heat deposition power in the core is 0.04 mW for the dose rate of 3 Gy/min where the temperature sensitivity of the graphite is 1.4 mK/Gy. While the residuals of the Steinhart-hart equation fitting for the core thermistor were less than 0.1 mK, the temperature resolution of Model 350 is 1 mK. The temperature of the shield was kept within the 5 mK when the room temperature variation was about 0.5 K. Conclusion: The resolution of Model 350 for the temperature measurement and control is not good enough as the control system for the compact graphite calorimetry system. But The performance of Model 350 is good enough to maintain the temperature of the shield constantly. The Model 350 will be replaced by the AC resistance bridge (Model 372, Lake Shore Cryogenics) for the core temperature measurement and the jacket control.

  1. Electrochemical Corrosion Studies for Modeling Metallic Waste Form Release Rates

    SciTech Connect

    Poineau, Frederic; Tamalis, Dimitri

    2016-08-01

    The isotope 99Tc is an important fission product generated from nuclear power production. Because of its long half-life (t1/2 = 2.13 ∙ 105 years) and beta-radiotoxicity (β⁻ = 292 keV), it is a major concern in the long-term management of spent nuclear fuel. In the spent nuclear fuel, Tc is present as an alloy with Mo, Ru, Rh, and Pd called the epsilon-phase, the relative amount of which increases with fuel burn-up. In some separation schemes for spent nuclear fuel, Tc would be separated from the spent fuel and disposed of in a durable waste form. Technetium waste forms under consideration include metallic alloys, oxide ceramics and borosilicate glass. In the development of a metallic waste form, after separation from the spent fuel, Tc would be converted to the metal, incorporated into an alloy and the resulting waste form stored in a repository. Metallic alloys under consideration include Tc–Zr alloys, Tc–stainless steel alloys and Tc–Inconel alloys (Inconel is an alloy of Ni, Cr and iron which is resistant to corrosion). To predict the long-term behavior of the metallic Tc waste form, understanding the corrosion properties of Tc metal and Tc alloys in various chemical environments is needed, but efforts to model the behavior of Tc metallic alloys are limited. One parameter that should also be considered in predicting the long-term behavior of the Tc waste form is the ingrowth of stable Ru that occurs from the radioactive decay of 99Tc (99Tc → 99Ru + β⁻). After a geological period of time, significant amounts of Ru will be present in the Tc and may affect its corrosion properties. Studying the effect of Ru on the corrosion behavior of Tc is also of importance. In this context, we studied the electrochemical behavior of Tc metal, Tc-Ni alloys (to model Tc-Inconel alloy) and Tc-Ru alloys in acidic media. The study of Tc-U alloys has also been performed in order to better understand the

  2. Fatality rate of pedestrians and fatal crash involvement rate of drivers in pedestrian crashes: a case study of Iran.

    PubMed

    Kashani, Ali Tavakoli; Besharati, Mohammad Mehdi

    2016-04-20

    The aim of this study was to uncover patterns of pedestrian crashes. In the first stage, 34,178 pedestrian-involved crashes occurred in Iran during a four-year period were grouped into homogeneous clusters using a clustering analysis. Next, some in-cluster and inter-cluster crash patterns were analysed. The clustering analysis yielded six pedestrian crash groups. Car/van/pickup crashes on rural roads as well as heavy vehicle crashes were found to be less frequent but more likely to be fatal compared to other crash clusters. In addition, after controlling for crash frequency in each cluster, it was found that the fatality rate of each pedestrian age group as well as the fatal crash involvement rate of each driver age group varies across the six clusters. Results of present study has some policy implications including, promoting pedestrian safety training sessions for heavy vehicle drivers, imposing limitations over elderly heavy vehicle drivers, reinforcing penalties toward under 19 drivers and motorcyclists. In addition, road safety campaigns in rural areas may be promoted to inform people about the higher fatality rate of pedestrians on rural roads. The crash patterns uncovered in this study might also be useful for prioritizing future pedestrian safety research areas.

  3. Direct measurement of absorbed dose to water in HDR {sup 192}Ir brachytherapy: Water calorimetry, ionization chamber, Gafchromic film, and TG-43

    SciTech Connect

    Sarfehnia, Arman; Kawrakow, Iwan; Seuntjens, Jan

    2010-04-15

    Purpose: Gafchromic film and ionometric calibration procedures for HDR {sup 192}Ir brachytherapy sources in terms of dose rate to water are presented and the experimental results are compared to the TG-43 protocol as well as with the absolute dose measurement results from a water calorimetry-based primary standard. Methods: EBT-1 Gafchromic films, an A1SL Exradin miniature Shonka thimble type chamber, and an SI HDR 1000 Plus well-type chamber (Standard Imaging, Inc., Middleton, WI) with an ADCL traceable S{sub k} calibration coefficient (following the AAPM TG-43 protocol) were used. The Farmer chamber and Gafchromic film measurements were performed directly in water. All results were compared to direct and absolute absorbed dose to water measurements from a 4 deg. C stagnant water calorimeter. Results: Based on water calorimetry, the authors measured the dose rate to water to be 361{+-}7 {mu}Gy/(h U) at a 55 mm source-to-detector separation. The dose rate normalized to air-kerma strength for all the techniques agree with the water calorimetry results to within 0.83%. The overall 1-sigma uncertainty on water calorimetry, ionization chamber, Gafchromic film, and TG-43 dose rate measurement amounts to 1.90%, 1.44%, 1.78%, and 2.50%, respectively. Conclusions: This work allows us to build a more realistic uncertainty estimate for absorbed dose to water determination using the TG-43 protocol. Furthermore, it provides the framework necessary for a shift from indirect HDR {sup 192}Ir brachytherapy dosimetry to a more accurate, direct, and absolute measurement of absorbed dose to water.

  4. Identifying Hydrated Salts Using Simultaneous Thermogravimetric Analysis and Differential Scanning Calorimetry

    ERIC Educational Resources Information Center

    Harris, Jerry D.; Rusch, Aaron W.

    2013-01-01

    simultaneous thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) to characterize colorless, hydrated salts with anhydrous melting points less than 1100 degrees C. The experiment could be used to supplement the lecture discussing gravimetric techniques. It is…

  5. An Integrated-Circuit Temperature Sensor for Calorimetry and Differential Temperature Measurement.

    ERIC Educational Resources Information Center

    Muyskens, Mark A.

    1997-01-01

    Describes the application of an integrated-circuit (IC) chip which provides an easy-to-use, inexpensive, rugged, computer-interfaceable temperature sensor for calorimetry and differential temperature measurement. Discusses its design and advantages. (JRH)

  6. Characterizing Optical Loss in Orientation Patterned III-V Materials using Laser Calorimetry

    DTIC Science & Technology

    2014-03-27

    conversion materials that can be used in high power, tunable laser sources in the MIR range for numerous Air Force applications. This research......used in calorimetry for better insulation . ............. 35 ix

  7. From Nm-Scale Measurements Of Mineral Dissolution Rate To Overall Dissolution Rate Laws: A Case Study Based On Diopside

    NASA Astrophysics Data System (ADS)

    Daval, D.; Saldi, G.; Hellmann, R.; Knauss, K.

    2011-12-01

    While we expect conventional reactive transport simulations to provide reliable estimations of the evolution of fluid-rock interactions over time scales of centuries and even more, recent experimental studies showed that they could hardly be satisfactorily used on simplified systems (e.g. batch carbonation experiments on single minerals), on time scales of weeks [1]. Among the reasons for such inconsistencies is the nature of the rate laws used in the geochemical codes, which heavily relies on our description of the fundamental mechanisms involved during water(-CO2)-mineral reactions. Silicate dissolution constitutes a key step of GCS processes. Whereas the dissolution rate of silicate minerals has been extensively studied at far-from-equilibrium conditions, extrapolating such rates over a broad range of solution composition relevant for GCS has proven challenging. Regarding diopside, recent studies [2, 3] suggested that below 125 °C, an unexpected drop of the rate occurred for Gibbs free energies of reaction (ΔGr) as low as -76 kJ.mol-1, with severe consequences on our ability to predict the rate of complex processes such as carbonation reactions [3]. The mechanism responsible for such a drop remains unclear and therefore needs to be deciphered. An examination of our previous data [3] led us to envisage that two different, non-exclusive aspects were worth investigating: (i) the possible passivating ability of interfacial, nm-thick Si-rich layers developed on weathered silicate surface, and (ii) the stop of etch pits formation on crystal surface, each mechanism being found to be responsible for drops of olivine [1] and albite [4] dissolution rates, respectively. Our ongoing experiments aim at better constraining these two mechanisms, and determining in turn whether one of them could explain the above-mentioned drop of diopside dissolution rate. Classical flow-through experiments with controlled SiO2(aq) concentrations are combined with both ex situ AFM and VSI

  8. Using differential scanning calorimetry, laser refractometry, electrical conductivity and spectrophotometry for discrimination of different types of Bulgarian honey

    NASA Astrophysics Data System (ADS)

    Vlaeva, I.; Nikolova, K.; Bodurov, I.; Marudova, M.; Tsankova, D.; Lekova, S.; Viraneva, A.; Yovcheva, T.

    2017-01-01

    The potential of several physical methods for investigation of the botanical origin of honey has been discussed. Samples from the three most prevalent types of honey in Bulgaria (acacia, linden and honeydew) have been used. They have been examined by laser refractometry, UV, VIS and FTIR spectroscopy, electric conductivity measurement and differential scanning calorimetry. The purpose of this study was to reveal the physical characterizations of honeys from different flora produced in Bulgaria and to identify honeys with a high apitherapy potential for future studies.

  9. A compact low-temperature single crystal adsorption calorimetry setup for measuring coverage dependent heats of adsorption at cryogenic temperatures.

    PubMed

    Hörtz, Peter; Schäfer, Rolf

    2014-07-01

    Here we present the modification of an already existing Single Crystal Adsorption Calorimetry (SCAC) apparatus which has been extended by a compact cooling system to measure the coverage dependent heats of adsorption of gaseous compounds on thin metal substrates in a temperature range from 80 K to 430 K. The setup is characterized and its performance is tested by studying the adsorption of CO on Pt(111) at 150 K and 300 K. Coverage dependent sticking probabilities and heat of adsorption measurements are compared to previous experimental and theoretical studies proving the reliability of our compact low-temperature-SCAC setup.

  10. Development of GEM-Based Digital Hadron Calorimetry Using the SLAC KPiX Chip

    SciTech Connect

    White, A.; /Texas U., Arlington /Washington U., Seattle /Unlisted /SLAC

    2012-04-12

    The development of Digital Hadron Calorimetry for the SiD detector Concept for the International Linear Collider is described. The jet energy requirements of the ILC physics program are discussed. The concept of GEM-based digital hadron calorimetry is presented, followed by a description of, and results from, prototype detectors. Plans are described for the construction of 1m{sup 2} GEM-DHCAL planes to be tested as part of a future calorimeter stack.

  11. Influence of Motivational Design on Completion Rates in Online Self-Study Pharmacy-Content Courses

    ERIC Educational Resources Information Center

    Pittenger, Amy; Doering, Aaron

    2010-01-01

    Student retention rates are a constant concern in higher education, but this concern has become especially challenging as online courses become more common and there are widespread reports of low completion rates for online, self-study courses. We evaluated four self-study online pharmacy courses with a history of very high completion rates for…

  12. The Gifted Rating Scales-School Form: A Validation Study Based on Age, Gender, and Race

    ERIC Educational Resources Information Center

    Pfeiffer, Steven; Petscher, Yaacov; Kumtepe, Alper

    2008-01-01

    This study examined the internal consistency and validity of a new rating scale to identify gifted students, the Gifted Rating Scales-School Form (GRS-S). The study explored the effect of gender, race/ethnicity, age, and rater familiarity on GRS-S ratings. One hundred twenty-two students in first to eighth grade from elementary and middle schools…

  13. Isothermal calorimetry: impact of measurements error on heat of reaction and kinetic calculations.

    PubMed

    Papadaki, Maria; Nawada, Hosadu P; Gao, Jun; Fergusson-Rees, Andrew; Smith, Michael

    2007-04-11

    Heat flow and power compensation calorimetry measures the power generation of a reaction via an energy balance over an appropriately designed isothermal reactor. However, the measurement of the power generated by a reaction is a relative measurement, and calibrations are used to eliminate the contribution of a number of unknown factors. In this work the effect of the error in the measurement of temperature of electric power used in the calibrations and the heat transfer coefficient and baseline is assessed. It has been shown that the error in all aforementioned quantities reflects on the baseline and it can have a very serious impact on the accuracy of the measurement. The influence of the fluctuation of ambient temperature has been evaluated and a means of a correction that reduces its impact has been implemented. The temperature of dosed material is affected by the heat loses if reaction is performed at high temperature and low dosing rate. An experimental methodology is presented that can provide means of assessment of the actual temperature of the dosed material. Depending on the reacting system, the heat of evaporation could be included in the baseline, especially if non-condensable gases are produced during the course of the reaction.

  14. Analysis of Diffusional Solidification in a Wide-Gap Brazing Powder Mixture Using Differential Scanning Calorimetry

    NASA Astrophysics Data System (ADS)

    Corbin, Stephen F.; Murray, D. Clark; Bouthillier, Alain

    2016-12-01

    The diffusional solidification (DS) of a mixed powder system, consisting of pure Ni base metal powder and BNi-2 braze powder, suitable for wide-gap brazing was investigated using differential scanning calorimetry (DSC) and parallel microstructural examination. It was determined that very little interdiffusion between the powders developed in the solid state prior to braze powder melting. Once liquid formed, rapid DS occurred such that, when the powders were loosely mixed together, only 20 to 50 wt pct of the potential liquid fraction actually developed, leading to poor densification. Separating the braze and Ni into a layered structure leads to less DS, increased liquid formation ( i.e., 35 to 80 wt pct of the potential liquid fraction) and improved densification. The rate of isothermal solidification in layered structures consisting of 30 and 40 wt pct BNi-2 braze material was determined using DSC. After 30 minutes of braze time at 1323 K (1050 °C), complete IS occurred, thus avoiding the formation of a continuous network of large borides. The final microstructure of the IS mixtures consisted of a continuous matrix of solid solution Ni, with isolated and dispersed borides.

  15. Enzyme activity determination on macromolecular substrates by isothermal titration calorimetry: application to mesophilic and psychrophilic chitinases.

    PubMed

    Lonhienne, T; Baise, E; Feller, G; Bouriotis, V; Gerday, C

    2001-02-09

    Isothermal titration calorimetry has been applied to the determination of the kinetic parameters of chitinases (EC 3.2.1.14) by monitoring the heat released during the hydrolysis of chitin glycosidic bonds. Experiments were carried out using two different macromolecular substrates: a soluble polymer of N-acetylglucosamine and the insoluble chitin from crab shells. Different experimental temperatures were used in order to compare the thermodependence of the activity of two chitinases from the psychrophile Arthrobacter sp. TAD20 and of chitinase A from the mesophile Serratia marcescens. The method allowed to determine unequivocally the catalytic rate constant k(cat), the activation energy (E(a)) and the thermodynamic activation parameters (DeltaG(#), DeltaH(#), DeltaS(#)) of the chitinolytic reaction on the soluble substrate. The catalytic activity has also been determined on insoluble chitin, which displays an effect of substrate saturation by chitinases. On both substrates, the thermodependence of the activity of the psychrophilic chitinases was lower than that observed with the mesophilic counterpart.

  16. Non-isothermal crystallization kinetics and glass-forming ability of Ti41Zr25Be28Fe6 bulk metallic glass investigated by differential scanning calorimetry

    NASA Astrophysics Data System (ADS)

    Gong, Pan; Zhao, Shaofan; Wang, Xin; Yao, Kefu

    2015-07-01

    The non-isothermal crystallization kinetics and glass-forming ability of Ti41Zr25Be28Fe6 glassy alloy were investigated by differential scanning calorimetry. The activation energies corresponding to the characteristic temperatures have been calculated by Kissinger and Ozawa equations. Based on Kissinger-Akahira-Sunose and Ozawa-Flynn-Wall models, it has been found that the local activation energy is higher at the beginning of the crystallization process for the first exothermic peak. The local Avrami exponent indicates that the first-step crystallization is mainly a high-dimensional nucleation and growth with an increasing nucleation rate. According to the calculated fragility index, Ti41Zr25Be28Fe6 alloy can be classified as "strong glass former." The studied alloy also possesses a critical size up to centimeter order, and the high glass-forming ability is probably related to the relatively low Gibbs energy difference between the liquid and crystalline states. The critical cooling rate of Ti41Zr25Be28Fe6 glassy alloy has also been determined using Barandiaran-Colmenero's method.

  17. Kinetics of Cold-Cap Reactions for Vitrification of Nuclear Waste Glass Based on Simultaneous Differential Scanning Calorimetry - Thermogravimetry (DSC-TGA) and Evolved Gas Analysis (EGA)

    SciTech Connect

    Rodriguez, Carmen P.; Pierce, David A.; Schweiger, Michael J.; Kruger, Albert A.; Chun, Jaehun; Hrma, Pavel R.

    2013-12-03

    For vitrifying nuclear waste glass, the feed, a mixture of waste with glass-forming and modifying additives, is charged onto the cold cap that covers 90-100% of the melt surface. The cold cap consists of a layer of reacting molten glass floating on the surface of the melt in an all-electric, continuous glass melter. As the feed moves through the cold cap, it undergoes chemical reactions and phase transitions through which it is converted to molten glass that moves from the cold cap into the melt pool. The process involves a series of reactions that generate multiple gases and subsequent mass loss and foaming significantly influence the mass and heat transfers. The rate of glass melting, which is greatly influenced by mass and heat transfers, affects the vitrification process and the efficiency of the immobilization of nuclear waste. We studied the cold-cap reactions of a representative waste glass feed using both the simultaneous differential scanning calorimetry thermogravimetry (DSC-TGA) and the thermogravimetry coupled with gas chromatography-mass spectrometer (TGA-GC-MS) as complementary tools to perform evolved gas analysis (EGA). Analyses from DSC-TGA and EGA on the cold-cap reactions provide a key element for the development of an advanced cold-cap model. It also helps to formulate melter feeds for higher production rate.

  18. Digital holographic interferometry: A novel optical calorimetry technique for radiation dosimetry

    SciTech Connect

    Cavan, Alicia; Meyer, Juergen

    2014-02-15

    Purpose: To develop and demonstrate the proof-of-principle of a novel optical calorimetry method to determine radiation absorbed dose in a transparent medium. Methods: The calorimetric property of water is measured during irradiation by means of an interferometer, which detects temperature-induced changes in the refractive index that can be mathematically related to absorbed dose. The proposed method uses a technique called digital holographic interferometry (DHI), which comprises an optical laser interferometer setup and consecutive physical reconstruction of the recorded wave fronts by means of the Fresnel transform. This paper describes the conceptual framework and provides the mathematical basis for DHI dosimetry. Dose distributions from a high dose rate Brachytherapy source were measured by a prototype optical setup to demonstrate the feasibility of the approach. Results: The developed DHI dosimeter successfully determined absorbed dose distributions in water in the region adjacent to a high dose rate Brachytherapy source. A temperature change of 0.0381 K across a distance of 6.8 mm near the source was measured, corresponding to a dose of 159.3 Gy. The standard deviation in a typical measurement set was ±3.45 Gy (corresponding to an uncertainty in the temperature value of ±8.3 × 10{sup −4} K). The relative dose fall off was in agreement with treatment planning system modeled data. Conclusions: First results with a prototype optical setup and a Brachytherapy source demonstrate the proof-of-principle of the approach. The prototype achieves high spatial resolution of approximately 3 × 10{sup −5} m. The general approach is fundamentally independent of the radiation type and energy. The sensitivity range determined indicates that the method is predominantly suitable for high dose rate applications. Further work is required to determine absolute dose in all three dimensions.

  19. Detection of a new 'nematic-like' phase in liquid crystal-amphiphile mixture by differential scanning calorimetry

    SciTech Connect

    Dan, Kaustabh Roy, Madhusudan Datta, Alokmay

    2014-04-24

    Differential Scanning Calorimetry (DSC) studies on phase transitions of the pure liquid crystalline material N-4-methoxybenzylidene-4-butylaniline (MBBA) and mixtures of MBBA and the amphiphile Stearic Acid (StA) show significant changes in the behavior of mixture from pure MBBA, as regards the nematic-isotropic (N-I) transition temperature (T{sub c}) and other thermodynamic parameters like enthalpy, specific heat and activation energy with concentration of StA. In particular, the convexity of the Arrhenius plot in pure MBBA vanishes with StA concentration pointing to the formation of a new, perhaps 'nematic-like', phase in the mixtures.

  20. Determination of Volatility of Ionic Liquids at the Nanoscale by means of Ultra-Fast Scanning Calorimetry - the Method

    NASA Astrophysics Data System (ADS)

    Ahrenberg, Mathias; Beck, Martin; Schmidt, Christin; Verevkin, Sergey P.; Kessler, Olaf; Kragl, Udo; Schick, Christoph

    2015-03-01

    We present a new method for the determination of the vapour pressure of low volatile compounds using differential fast scanning calorimetry. We have developed and proven this method using the ionic liquids [EMIm][NTf2] and [EMIm][NO3] at temperatures up to 750 K and in different atmospheres to distinguish between decomposition and evaporation1. It was demonstrated that evaporation is still the dominating process of mass loss even at temperatures 100 K above the onset of decomposition as measured with common techniques, e.g TGA. Since the method allows very high heating rates (up to 106 K/s)2, much higher temperatures can be reached in the measurement of the vapour pressure as compared to common devices without significant decomposition of the ionic liquid. Furthermore, this method represents an improvement of the boiling point estimation of ILs due to the large accessible temperature range of mass loss rate determination.

  1. A Study of the Education Rate of Return for Rural Residents in Northwest Minority Areas

    ERIC Educational Resources Information Center

    Baicai, Sun

    2015-01-01

    Studying the rate of return for rural residents in minority areas can give a good explanation for the problems of children enrolling in school and dropping out. On the whole, the education rate of return for rural residents in northwest minority areas is low, the Mincer function estimate is 2%, and the Heckman model estimate is 2.49%. The rate of…

  2. Thermodynamic analysis of Bacillus subtilis endospore protonation using isothermal titration calorimetry

    NASA Astrophysics Data System (ADS)

    Harrold, Zoë R.; Gorman-Lewis, Drew

    2013-05-01

    Bacterial proton and metal adsorption reactions have the capacity to affect metal speciation and transport in aqueous environments. We coupled potentiometric titration and isothermal titration calorimetry (ITC) analyses to study Bacillus subtilis spore-proton adsorption. We modeled the potentiometric data using a four and five-site non-electrostatic surface complexation model (NE-SCM). Heats of spore surface protonation from coupled ITC analyses were used to determine site specific enthalpies of protonation based on NE-SCMs. The five-site model resulted in a substantially better model fit for the heats of protonation but did not significantly improve the potentiometric titration model fit. The improvement observed in the five-site protonation heat model suggests the presence of a highly exothermic protonation reaction circa pH 7 that cannot be resolved in the less sensitive potentiometric data. From the log Ks and enthalpies we calculated corresponding site specific entropies. Log Ks and site concentrations describing spore surface protonation are statistically equivalent to B. subtilis cell surface protonation constants. Spore surface protonation enthalpies, however, are more exothermic relative to cell based adsorption suggesting a different bonding environment. The thermodynamic parameters defined in this study provide insight on molecular scale spore-surface protonation reactions. Coupled ITC and potentiometric titrations can reveal highly exothermic, and possibly endothermic, adsorption reactions that are overshadowed in potentiometric models alone. Spore-proton adsorption NE-SCMs derived in this study provide a framework for future metal adsorption studies.

  3. Toxic effects of chrysoidine on human serum albumin: isothermal titration calorimetry and spectroscopic investigations.

    PubMed

    Sun, Haoyu; Liu, Yingxue; Li, Meng; Han, Songlin; Yang, Xudan; Liu, Rutao

    2016-03-01

    Chrysoidine is widely used in industry as a type of azo dye, and is sometimes used illegally as a food additive despite its potential toxicity. Human serum albumin (HSA) is one of the most important proteins in blood plasma and possesses major physiological functions. In the present study, the conformational and functional effects of chrysoidine on HSA were investigated by isothermal titration calorimetry (ITC), multiple spectroscopic methods, a molecular docking study and an esterase activity assay. Based on the ITC results, the binding stoichiometry of chrysoidine to HSA was estimated to be 1.5:1, and was a spontaneous process via a single hydrogen bond. The binding of chrysoidine to HSA induced dynamic quenching in fluorescence, and changes in secondary structure and in the microenvironment of the Trp-214 residue. In addition, the hydrogen bond (1.80 Å) formed between the chrysoidine molecule and the Gln-211 residue. The esterase activity of HSA decreased following the addition chrysoidine due to the change in protein structure. This study details the direct interaction between chrysoidine and HSA at the molecular level and the mechanism for toxicity as a result of the functional changes induced by HSA structural variation upon binding to chrysoidine in vitro. This study provides useful information towards detailing the transportation mechanism and toxicity of chrysoidine in vivo.

  4. Probing the binding mechanisms of α-tocopherol to trypsin and pepsin using isothermal titration calorimetry, spectroscopic, and molecular modeling methods.

    PubMed

    Li, Xiangrong; Ni, Tianjun

    2016-06-01

    α-Tocopherol is a required nutrient for a variety of biological functions. In this study, the binding of α-tocopherol to trypsin and pepsin was investigated using isothermal titration calorimetry (ITC), steady-state and time-resolved fluorescence measurements, circular dichroism (CD) spectroscopy, and molecular modeling methods. Thermodynamic investigations reveal that α-tocopherol binds to trypsin/pepsin is synergistically driven by enthalpy and entropy. The fluorescence experimental results indicate that α-tocopherol can quench the fluorescence of trypsin/pepsin through a static quenching mechanism. The binding ability of α-tocopherol with trypsin/pepsin is in the intermediate range, and one molecule of α-tocopherol combines with one molecule of trypsin/pepsin. As shown by circular dichroism (CD) spectroscopy, α-tocopherol may induce conformational changes of trypsin/pepsin. Molecular modeling displays the specific binding site and gives information about binding forces and α-tocopherol-tryptophan (Trp)/tyrosine (Tyr) distances. In addition, the inhibition rate of α-tocopherol on trypsin and pepsin was studied. The study provides a basic data set for clarifying the binding mechanisms of α-tocopherol with trypsin and pepsin and is helpful for understanding its biological activity in vivo.

  5. Simulation study of the influence of PEB reaction rates on resist LER

    NASA Astrophysics Data System (ADS)

    Bhattarai, Suchit; Neureuther, Andrew R.; Naulleau, Patrick P.

    2015-03-01

    A stochastic resist simulator has first been calibrated to experimental results performed on a commercially available EUV resist, and subsequently has been used to study the influence of acid/base quenching rate and the polymer deprotection rate on resist LER for 22 nm half-pitch lines/spaces. Results indicate that larger quenching rates and smaller deprotection rates result in improved LER performance by causing an increase in the dose to size. With nominal quenching rate determined from literature, halving the deprotection rate relative to nominal value reduces the LER by 33%, while the dose to size increases by 2x. With nominal deprotection rate determined from literature, results indicate a low sensitivity of LER to quenching rate. Expected noise at the line edge calculated by using a shot noise model accounting for absorbed photons, acid, and base count, provides a good explanation for the LER trends calculated for several reaction rate scenarios.

  6. Evaluation of Staphylococcus aureus DNA aptamer by enzyme-linked aptamer assay and isothermal titration calorimetry.

    PubMed

    Bayraç, Ceren; Öktem, Hüseyin Avni

    2017-02-01

    To monitor the specificity of Staphylococcus aureus aptamer (SA-31) against its target cell, we used enzyme-linked aptamer assay. In the presence of target cell, horseradish peroxidase-conjugated streptavidin bound to biotin-labeled SA-31 showed specific binding to S  aureus among 3 different bacteria with limit of detection of 10(3) colony-forming unit per milliliter. The apparent Ka was 1.39 μM(-1)  ± 0.3 μM(-1) . The binding of SA-31 to membrane proteins extracted from cell surface was characterized using isothermal titration calorimetry, and the effect of changes in binding temperature and salt concentrations of binding buffer was evaluated based on thermodynamic parameters (Ka , ΔH, and ΔG). Since binding of aptamer to its targets solely depends on its 3-dimensional structure under experimental conditions used in selection process, the change in temperature and ion concentration changed the affinity of SA-31 to its target on surface of bacteria. At 4°C, SA-31 did not show an affinity to its target with poor heat change upon injection of membrane fraction to aptamer solution. However, the apparent association constants of SA-31 slightly varied from Ka  = 1.56 μM(-1)  ± 0.69 μM(-1) at 25°C to Ka  = 1.03 μM(-1)  ± 0.9 μM(-1) at 37°C. At spontaneously occurring exothermic binding reactions, affinities of S aureus aptamer to its target were also 9.44 μM(-1)  ± 0.38 μM(-1) at 50mM, 1.60 μM(-1)  ± 0.11 μM(-1) at 137mM, and 3.28 μM(-1)  ± 0.46 μM(-1) at 200 mM of salt concentration. In this study, it was demonstrated that enzyme-linked aptamer assay and isothermal titration calorimetry were useful tools for studying the fundamental binding mechanism between a DNA aptamer and its target on the outer surface of S aureus.

  7. Applications of differential scanning calorimetry for thermal stability analysis of proteins: qualification of DSC.

    PubMed

    Wen, Jie; Arthur, Kelly; Chemmalil, Letha; Muzammil, Salman; Gabrielson, John; Jiang, Yijia

    2012-03-01

    Differential scanning calorimetry (DSC) has been used to characterize protein thermal stability, overall conformation, and domain folding integrity by the biopharmaceutical industry. Recently, there have been increased requests from regulatory agencies for the qualification of characterization methods including DSC. Understanding the method precision can help determine what differences between samples are significant and also establish the acceptance criteria for comparability and other characterization studies. In this study, we identify the parameters for the qualification of DSC for thermal stability analysis of proteins. We use these parameters to assess the precision and sensitivity of DSC and demonstrate that DSC is suitable for protein thermal stability analysis for these purposes. Several molecules from different structural families were studied. The experiments and data analyses were performed by different analysts using different instruments at different sites. The results show that the (apparent) thermal transition midpoint (T(m)) values obtained for the same protein by same and different instruments and/or analysts are quite reproducible, and the profile similarity values obtained for the same protein from the same instrument are also high. DSC is an appropriate method for assessing protein thermal stability and conformational changes.

  8. Probing the binding of procyanidin B3 to human serum albumin by isothermal titration calorimetry

    NASA Astrophysics Data System (ADS)

    Li, Xiangrong; Yan, Yunhui

    2015-02-01

    Proanthocyanidins are a mixture of monomers, oligomers, and polymers of flavan-3-ols that are widely distributed in the plant kingdom. One of the most widely studied proanthocyanidins is procyanidin B3. In this study, the interaction between procyanidin B3 and human serum albumin (HSA) was investigated using isothermal titration calorimetry (ITC). Thermodynamic investigations reveal that the hydrogen bond and van der Waals force are the major binding forces in the binding of procyanidin B3 to HSA. The binding of procyanidin B3 to HSA is driven by favorable enthalpy and unfavorable entropy. The obtained binding constant for procyanidin B3 with HSA is in the intermediate range and the equilibrium fraction of unbound procyanidin B3 fu > 90% at the physiological concentration of HSA shows that procyanidin B3 can be stored and transported from the circulatory system to reach its target site. The stoichiometric binding number n approximately equals to 1, suggesting that one molecule of procyanidin B3 combines with one molecule of HSA and no more procyanidin B3 binding to HSA occurs at the concentration used in this study.

  9. Differential scanning calorimetry as a tool for protein folding and stability.

    PubMed

    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.

  10. Interaction of oridonin with human serum albumin by isothermal titration calorimetry and spectroscopic techniques.

    PubMed

    Li, Xiangrong; Yang, Zhenhua

    2015-05-05

    Oridonin has been traditionally and widely used for treatment of various human diseases due to its uniquely biological, pharmacological and physiological functions. In this study, the interaction between oridonin and human serum albumin (HSA) was investigated using isothermal titration calorimetry (ITC), in combination with fluorescence spectroscopy and UV-vis absorption spectroscopy. We found that the hydrogen bond and van der Waals force are the major binding forces in the binding of oridonin to HSA. The binding of oridonin to HSA is driven by favorable enthalpy and unfavorable entropy. Oridonin can quench the fluorescence of HSA through a static quenching mechanism. The binding constant between oridonin and HSA is moderate and the equilibrium fraction of unbound oridonin f(u) > 60%. Binding site I is found to be the primary binding site for oridonin. Additionally, oridonin may induce conformational changes of HSA and affect its biological function as the carrier protein. The results of the current study suggest that oridonin can be stored and transported from the circulatory system to reach its target organ to provide its therapeutic effects. But its side-effect in the clinics cannot be overlook. The study provides an accurate and full basic data for clarifying the binding mechanism of oridonin with HSA and is helpful for understanding its effect on protein function during the blood transportation process and its biological activity in vivo.

  11. Use of age-adjusted rates of suicide in time series studies in Israel.

    PubMed

    Bridges, F Stephen; Tankersley, William B

    2009-01-01

    Durkheim's modified theory of suicide was examined to explore how consistent it was in predicting Israeli rates of suicide from 1965 to 1997 when using age-adjusted rates rather than crude ones. In this time-series study, Israeli male and female rates of suicide increased and decreased, respectively, between 1965 and 1997. Conforming to Durkheim's modified theory, the Israeli male rate of suicide was lower in years when rates of marriage and birth are higher, while rates of suicide are higher in years when rates of divorce are higher, the opposite to that of Israeli women. The corrected regression coefficients suggest that the Israeli female rate of suicide remained lower in years when rate of divorce is higher, again the opposite suggested by Durkheim's modified theory. These results may indicate that divorce affects the mental health of Israeli women as suggested by their lower rate of suicide. Perhaps the "multiple roles held by Israeli females creates suicidogenic stress" and divorce provides some sense of stress relief, mentally speaking. The results were not as consistent with predictions suggested by Durkheim's modified theory of suicide as were rates from the United States for the same period nor were they consistent with rates based on "crude" suicide data. Thus, using age-adjusted rates of suicide had an influence on the prediction of the Israeli rate of suicide during this period.

  12. Can student self-ratings be compared with peer ratings? A study of measurement invariance of multisource feedback.

    PubMed

    Lee, Keng-Lin; Tsai, Shih-Li; Chiu, Yu-Ting; Ho, Ming-Jung

    2016-05-01

    Measurement invariance is a prerequisite for comparing measurement scores from different groups. In medical education, multi-source feedback (MSF) is utilized to assess core competencies, including the professionalism. However, little attention has been paid to the measurement invariance of assessment instruments; that is, whether an instrument holds the same meaning across different rater groups. To examine the measurement invariance of the National Taiwan University professionalism MSF (NTU P-MSF) in order to determine whether medical students' self-rating can be compared to their peers' rating. An eight-factor model was specified for confirmatory factor analysis to examine the construct validity of the NTU P-MSF. Cronbach's alpha was computed for the items of each domain to evaluate internal consistent reliability. The same eight-factor model was used for multi-group confirmatory factor analyses. Four hierarchical models were specified to test configural (i.e., identical factor-item relationship), metric (i.e., identical factor loadings), scalar (i.e., identical intercepts), and error variance across self-rating and peer rating groups. One hundred and twenty second-year medical students from weekly discussion groups conducted as part of a medical professionalism course agreed to use the NTU P-MSF to assess themselves or their discussion group peers. NTU P-MSF assessment scores were a good fit for the eight-factor model among self group and peer group. The Cronbach's alpha coefficients of students' NTU P-MSF scores and peers' scores ranged from 0.76 to 0.89 and 0.84 to 0.91, respectively indicating that the NTU P-MSF scores also have good internal consistent reliability between both groups. In addition, same factor structure and similar factor loadings and intercepts of NTU P-MSF scores between both groups indicate that NTU P-MSF scores had configural, metric, and scalar invariance. Thus, students' self-assessments and peer assessments can be compared in terms of

  13. Technical decision making with higher order structure data: utilization of differential scanning calorimetry to elucidate critical protein structural changes resulting from oxidation.

    PubMed

    Arthur, Kelly K; Dinh, Nikita; Gabrielson, John P

    2015-04-01

    Differential scanning calorimetry (DSC) is a useful tool for monitoring thermal stability of the molecular conformation of proteins. Here, we present an example of the sensitivity of DSC to changes in stability arising from a common chemical degradation pathway, oxidation. This Note is part of a series of industry case studies demonstrating the application of higher order structure data for technical decision making. For this study, six protein products from three structural classes were evaluated at multiple levels of oxidation. For each protein, the melting temperature (Tm ) decreased linearly as a function of oxidation; however, differences in the rate of change in Tm , as well as differences in domain Tm stability were observed across and within structural classes. For one protein, analysis of the impact of oxidation on protein function was also performed. For this protein, DSC was shown to be a leading indicator of decreased antigen binding suggesting a subtle conformation change may be underway that can be detected using DSC prior to any observable impact on product potency. Detectable changes in oxidized methionine by mass spectrometry (MS) occurred at oxidation levels below those with a detectable conformational or functional impact. Therefore, by using MS, DSC, and relative potency methods in concert, the intricate relationship between a primary structural modification, changes in conformational stability, and functional impact can be elucidated.

  14. Forward calorimetry for heavy-ion physics at the STAR experiment

    NASA Astrophysics Data System (ADS)

    Brown, Daniel; STAR Experiment at RHIC Collaboration; STAR Forward Calorimeter Group Team

    2017-01-01

    A forward calorimeter utilizing hadronic and electromagnetic calorimetry at the STAR experiment of RHIC will achieve a variety of physics goals. These goals include studying long-range rapidity correlations, event plane correlations in heavy-ion interactions, and studying the gluon contribution to the proton spin. Upgrades to the AGS E864 lead-scintillating fiber calorimeter have increased spatial resolution by utilizing cell pixelization. Light collection has been optimized and fringe field effects have been minimized by the introduction of Fresnel lenses and mu-metal shielding. A prototype consisting of a 2x3 cell stack was installed into the forward region of STAR for the end of run16. This prototype investigated the introduction of these new techniques as well as a trial of Silicon Photomultipliers (SiPMs) as an alternate to traditional Photomultiplier Tubes (PMTs). SiPMs do not suffer from fringe field effects, but are susceptible to radiation damage by neutrons, so their performance during the prototype operation was analyzed. This talk will discuss the effects of Fresnel lenses on light collection, mu-metal shielding effects on PMTs, and radiation effects on SiPMs.

  15. Isothermal titration calorimetry as a tool to determine the thermodynamics of demicellization processes

    NASA Astrophysics Data System (ADS)

    Kessler, Anne; Zeeb, Benjamin; Kranz, Bertolt; Menéndez-Aguirre, Orquídea; Fischer, Lutz; Hinrichs, Jörg; Weiss, Jochen

    2012-10-01

    Demicellization of a 90 mM sodium dodecyl sulfate (SDS) solution in water at 10, 22, and 30 °C was studied by isothermal titration calorimetry (ITC). ΔH of the demicellization process was strongly temperature dependent, having an exothermic progression (-20.4 ± 0.9 kJ/mol, max) at 10 °C and an endothermic one (3.7 ± 1.2 kJ/mol, max) at 30 °C. ΔH for micelle dilution followed a slightly endothermic progression (0.9 ± 0.5 kJ/mol at 30 °C, 0.7 ± 1.3 kJ/mol at 22 °C, and 0.0 ± 0.5 kJ/mol at 10 °C) at all studied temperatures. No differences in ΔH for micelle dilution and demicellization was observed at 22 °C. The temperature dependence of ΔH measured by ITC could be related to hydrophobic interactions. Therefore, ITC was shown to be a useful tool to describe the thermodynamics of demicellization processes and in addition to determine alterations in ΔH caused by changes in hydrophobic and steric/electrostatic interactions.

  16. Advances in the analysis of isothermal titration calorimetry data for ligand-DNA interactions.

    PubMed

    Buurma, Niklaas J; Haq, Ihtshamul

    2007-06-01

    Isothermal titration calorimetry (ITC) is a well established technique for the study of biological interactions. The strength of ITC is that it directly measures enthalpy changes associated with interactions. Experiments can also yield binding isotherms allowing quantification of equilibrium binding constants, hence an almost complete thermodynamic profile can be established. Principles and application of ITC have been well documented over recent years, experimentally the technique is simple to use and in ideal scenarios data analysis is trivial. However, ITC experiments can be designed such that previously inaccessible parameters can be evaluated. We outline some of these advances, including (1) exploiting different experimental conditions; (2) low affinity systems; (3) high affinity systems and displacement assays. In addition we ask the question: What if data cannot be fit using the fitting functions incorporated in the data-analysis software that came with your ITC? Examples where such data might be generated include systems following non 1:n binding patterns and systems where binding is coupled to other events such as ligand dissociation. Models dealing with such data are now appearing in literature and we summarise examples relevant for the study of ligand-DNA interactions.

  17. Assessment of fluidity of different invasomes by electron spin resonance and differential scanning calorimetry.

    PubMed

    Dragicevic-Curic, Nina; Friedrich, Manfred; Petersen, Silvia; Scheglmann, Dietrich; Douroumis, Dennis; Plass, Winfried; Fahr, Alfred

    2011-06-30

    The aim of this study was to investigate the influence of membrane-softening components (terpenes/terpene mixtures, ethanol) on fluidity of phospholipid membranes in invasomes, which contain besides phosphatidylcholine and water, also ethanol and terpenes. Also mTHPC was incorporated into invasomes in order to study its molecular interaction with phospholipids in vesicular membranes. Fluidity of bilayers was investigated by electron spin resonance (ESR) using spin labels 5- and 16-doxyl stearic acid and by differential scanning calorimetry (DSC). Addition of 1% of a single terpene/terpene mixture led to significant fluidity increase around the C16 atom of phospholipid acyl chains comprising the vesicles. However, it was not possible to differentiate between the influences of single terpenes or terpene mixtures. Incorporation of mTHPC into the bilayer of vesicles decreased fluidity near the C16 atom of acyl chains, indicating its localization in the inner hydrophobic zone of bilayers. These results are in agreement with DSC measurements, which showed that terpenes increased fluidity of bilayers, while mTHPC decreased fluidity. Thus, invasomes represent vesicles with very high membrane fluidity. However, no direct correlation between fluidity of invasomes and their penetration enhancing ability was found, indicating that besides fluidity also other phenomena might be responsible for improved skin delivery of mTHPC.

  18. Strategies for assessing proton linkage to bimolecular interactions by global analysis of isothermal titration calorimetry data.

    PubMed

    Coussens, Nathan P; Schuck, Peter; Zhao, Huaying

    2012-09-01

    Isothermal titration calorimetry (ITC) is a traditional and powerful method for studying the linkage of ligand binding to proton uptake or release. The theoretical framework has been developed for more than two decades and numerous applications have appeared. In the current work, we explored strategic aspects of experimental design. To this end, we simulated families of ITC data sets that embed different strategies with regard to the number of experiments, range of experimental pH, buffer ionization enthalpy, and temperature. We then re-analyzed the families of data sets in the context of global analysis, employing a proton linkage binding model implemented in the global data analysis platform SEDPHAT, and examined the information content of all data sets by a detailed statistical error analysis of the parameter estimates. In particular, we studied the impact of different assumptions about the knowledge of the exact concentrations of the components, which in practice presents an experimental limitation for many systems. For example, the uncertainty in concentration may reflect imperfectly known extinction coefficients and stock concentrations or may account for different extents of partial inactivation when working with proteins at different pH values. Our results show that the global analysis can yield reliable estimates of the thermodynamic parameters for intrinsic binding and protonation, and that in the context of the global analysis the exact molecular component concentrations may not be required. Additionally, a comparison of data from different experimental strategies illustrates the benefit of conducting experiments at a range of temperatures.

  19. Microtubule-associated proteins and tubulin interaction by isothermal titration calorimetry.

    PubMed

    Tsvetkov, P O; Barbier, P; Breuzard, G; Peyrot, V; Devred, F

    2013-01-01

    Microtubules play an important role in a number of vital cell processes such as cell division, intracellular transport, and cell architecture. The highly dynamic structure of microtubules is tightly regulated by a number of stabilizing and destabilizing microtubule-associated proteins (MAPs), such as tau and stathmin. Because of their importance, tubulin-MAPs interactions have been extensively studied using various methods that provide researchers with complementary but sometimes contradictory thermodynamic data. Isothermal titration calorimetry (ITC) is the only direct thermodynamic method that enables a full thermodynamic characterization (stoichiometry, enthalpy, entropy of binding, and association constant) of the interaction after a single titration experiment. This method has been recently applied to study tubulin-MAPs interactions in order to bring new insights into molecular mechanisms of tubulin regulation. In this chapter, we review the technical specificity of this method and then focus on the use of ITC in the investigation of tubulin-MAPs binding. We describe technical issues which could arise during planning and carrying out the ITC experiments, in particular with fragile proteins such as tubulin. Using examples of stathmin and tau, we demonstrate how ITC can be used to gain major insights into tubulin-MAP interaction.

  20. Immersion calorimetry of fine coal particles and its relation to flotation

    SciTech Connect

    Melkus, T.G.; Chiang, S.H.; Wen, W.W.

    1987-01-01

    A Setaram C-80 heat flux microcalorimeter was used to study the surface and interfacial properties of fine coal particles in water containing flotation agents via heat of immersion measurements. Heat of immersion (..delta..H/sub imm/) is usually a small exothermic quantity and can be used to characterize a solid in terms of its relative hydrophobicity or hydrophilicity. The effects of coal type, surface oxidation, mineral matter content, kerosene concentration, and pH on the wetting characteristics were investigated. Although coal is a heterogeneous mixture of organic and inorganic materials, immersional calorimetry has proven to be quite helpful in measuring surface properties of coal, and the following conclusions can be drawn: The heat of immersion decreased with increasing kerosene concentration, which corresponds to the coal particles increasing hydrophobicity; in varying the pH, the ..delta..H/sub imm/ went through a minimum at a pH value of 6.5 to 7.0, which coincides with the reported optimum pH range for flotation; both oxidation and clay slime coating (addition of kaolin), which are known to make the coal less hydrophobic, increased the ..delta..H/sub imm/; and the trends that were shown to exist in the heat of immersion measurements (for varying kerosene concentration, pH oxidation, and clay slime coating) correlated well with independent flotation experiments. 16 refs., 6 figs., 2 tabs.

  1. Interfacial chemistry at metal/CdTe contacts as probed by differential scanning calorimetry

    NASA Astrophysics Data System (ADS)

    Lin, W.-Y.; Wei, C.; Rajeshwar, K.

    1994-10-01

    All four possible chemical reactivity patterns, namely, outdiffusion of Te (metal-Cd alloy formation), Cd outdiffusion (metal telluride compound formation), comparable chemical reactivity of the metal towards both Cd and Te (no Cd or Te outdiffusion), and chemical inertness of the metal towards CdTe, were differentiated via the differential scanning calorimetry (DSC) technique from a study of the interaction of nine different metals toward CdTe powder. The fusion signatures of free Cd or Te, exotherms due to compound or alloy formation, along with the thermal transitions of the metal telluride and/or the intermetallic were used for this purpose. These reactivity patterns are discussed within the framework of two different thermodynamic models. Both virgin and chemically etched CdTe surfaces were examined, and found to exhibit rather different reactivity trends towards the metal. The ramifications of these results in terms of the electronic properties of metal/CdTe contacts are discussed. Finally, DSC is shown to be useful for probing alterations in the CdTe surface chemistry as a result of the etch treatment.

  2. Sub-picowatt resolution calorimetry with niobium nitride thin-film thermometer

    NASA Astrophysics Data System (ADS)

    Dechaumphai, Edward; Chen, Renkun

    2014-09-01

    High-resolution calorimetry has many important applications such as probing nanoscale thermal transport and studying the thermodynamics of biological and chemical systems. In this work, we demonstrated a calorimeter with an unprecedentedly high resolution at room temperature using a high-performance resistive thermometry material, niobium nitride (NbNx). Based on a theoretical analysis, we first showed that the heat flux resolution of a resistive-thermometry based calorimeter depends on the parasitic thermal conductance of the device and the temperature coefficient of resistance (TCR) of the thermometer, when the noise is limited by the Johnson noise. Based on this analysis, we then developed a calorimeter using NbNx as the thermometry material because it possesses both high TCR (˜0.67%/K) and a low thermal conductivity (k ˜ 1.1 W/m K). This calorimeter, when used with the modulated heating scheme, demonstrated an unprecedentedly high power resolution of 0.26 pW at room temperature. In addition, NbNx based resistive thermometry can also be extended to cryogenic temperature, where the TCR is shown to be significantly higher.

  3. Sub-picowatt resolution calorimetry with niobium nitride thin-film thermometer

    SciTech Connect

    Dechaumphai, Edward; Chen, Renkun

    2014-09-15

    High-resolution calorimetry has many important applications such as probing nanoscale thermal transport and studying the thermodynamics of biological and chemical systems. In this work, we demonstrated a calorimeter with an unprecedentedly high resolution at room temperature using a high-performance resistive thermometry material, niobium nitride (NbN{sub x}). Based on a theoretical analysis, we first showed that the heat flux resolution of a resistive-thermometry based calorimeter depends on the parasitic thermal conductance of the device and the temperature coefficient of resistance (TCR) of the thermometer, when the noise is limited by the Johnson noise. Based on this analysis, we then developed a calorimeter using NbN{sub x} as the thermometry material because it possesses both high TCR (∼0.67%/K) and a low thermal conductivity (k ∼ 1.1 W/m K). This calorimeter, when used with the modulated heating scheme, demonstrated an unprecedentedly high power resolution of 0.26 pW at room temperature. In addition, NbN{sub x} based resistive thermometry can also be extended to cryogenic temperature, where the TCR is shown to be significantly higher.

  4. Application of TZERO calibrated modulated temperature differential scanning calorimetry to characterize model protein formulations.

    PubMed

    Badkar, Aniket; Yohannes, Paulos; Banga, Ajay

    2006-02-17

    The objective of this study was to evaluate the feasibility of using T(ZERO) modulated temperature differential scanning calorimetry (MDSC) as a novel technique to characterize protein solutions using lysozyme as a model protein and IgG as a model monoclonal antibody. MDSC involves the application of modulated heating program, along with the standard heating program that enables the separation of overlapping thermal transitions. Although characterization of unfolding transitions for protein solutions requires the application of high sensitive DSC, separation of overlapping transitions like aggregation and other exothermic events may be possible only by use of MDSC. A newer T(ZERO) calibrated MDSC model from TA instruments that has improved sensitivity than previous models was used. MDSC analysis showed total, reversing and non-reversing heat flow signals. Total heat flow signals showed a combination of melting endotherms and overlapping exothermic events. Under the operating conditions used, the melting endotherms were seen in reversing heat flow signal while the exothermic events were seen in non-reversing heat flow signal. This enabled the separation of overlapping thermal transitions, improved data analysis and decreased baseline noise. MDSC was used here for characterization of lysozyme solutions, but its feasibility for characterizing therapeutic protein solutions needs further assessment.

  5. Polymorphism in nimodipine raw materials: development and validation of a quantitative method through differential scanning calorimetry.

    PubMed

    Riekes, Manoela Klüppel; Pereira, Rafael Nicolay; Rauber, Gabriela Schneider; Cuffini, Silvia Lucia; de Campos, Carlos Eduardo Maduro; Silva, Marcos Antonio Segatto; Stulzer, Hellen Karine

    2012-11-01

    Due to the physical-chemical and therapeutic impacts of polymorphism, its monitoring in raw materials is necessary. The purpose of this study was to develop and validate a quantitative method to determine the polymorphic content of nimodipine (NMP) raw materials based on differential scanning calorimetry (DSC). The polymorphs required for the development of the method were characterized through DSC, X-ray powder diffraction (XRPD) and Raman spectroscopy and their polymorphic identity was confirmed. The developed method was found to be linear, robust, precise, accurate and specific. Three different samples obtained from distinct suppliers (NMP 1, NMP 2 and NMP 3) were firstly characterized through XRPD and DSC as polymorphic mixtures. The determination of their polymorphic identity revealed that all samples presented the Modification I (Mod I) or metastable form in greatest proportion. Since the commercial polymorph is Mod I, the polymorphic characteristic of the samples analyzed needs to be investigated. Thus, the proposed method provides a useful tool for the monitoring of the polymorphic content of NMP raw materials.

  6. High-precision isothermal titration calorimetry with automated peak-shape analysis.

    PubMed

    Keller, Sandro; Vargas, Carolyn; Zhao, Huaying; Piszczek, Grzegorz; Brautigam, Chad A; Schuck, Peter

    2012-06-05

    Isothermal titration calorimetry (ITC) is a powerful classical method that enables researchers in many fields to study the thermodynamics of molecular interactions. Primary ITC data comprise the temporal evolution of differential power reporting the heat of reaction during a series of injections of aliquots of a reactant into a sample cell. By integration of each injection peak, an isotherm can be constructed of total changes in enthalpy as a function of changes in solution composition, which is rich in thermodynamic information on the reaction. However, the signals from the injection peaks are superimposed by the stochastically varying time-course of the instrumental baseline power, limiting the precision of ITC isotherms. Here, we describe a method for automated peak assignment based on peak-shape analysis via singular value decomposition in combination with detailed least-squares modeling of local pre- and postinjection baselines. This approach can effectively filter out contributions of short-term noise and adventitious events in the power trace. This method also provides, for the first time, statistical error estimates for the individual isotherm data points. In turn, this results in improved detection limits for high-affinity or low-enthalpy binding reactions and significantly higher precision of the derived thermodynamic parameters.

  7. A Guide to Differential Scanning Calorimetry of Membrane and Soluble Proteins in Detergents.

    PubMed

    Yang, Zhengrong; Brouillette, Christie G

    2016-01-01

    Differential scanning calorimetry (DSC) detects protein thermal unfolding by directly measuring the heat absorbed. Simple DSC experiments that require relatively small amounts of pure material can provide a wealth of information related to structure, especially with respect to domain architecture, without the need for a complete thermodynamic analysis. Thus, DSC is an ideal additional tool for membrane protein characterization and also offers several advantages over indirect thermal unfolding methods. Integral membrane proteins (IMPs) that comprise both large multitopic transmembrane domains (TMDs) and extramembranous domains (EMDs) are differentially affected by detergent interactions with both domains. In fact, in some cases, destabilization of the EMD by detergent may dominate overall IMP stability. This chapter will (1) provide a perspective on the advantages of DSC for membrane protein characterization and stability measurements, including numerous examples spanning decades of research; (2) introduce models for the interaction and destabilization of IMPs by detergents; (3) discuss two case studies from the authors' lab; and (4) offer practical advice for performing DSC in the presence of detergents.

  8. Phlogopite: high temperature solution calorimetry, thermodynamic properties, Al-Si and stacking disorder, and phase equilibria

    SciTech Connect

    Clemens, J.D.; Circone, S.; Navrotsky, A.; McMillan, P.F.; Smith, B.K.; Wall, V.J.

    1987-09-01

    Two structural features complicate the thermodynamics of synthetic and natural micas. The first is a varying degree of tetrahedral Al-Si disorder. Raman spectroscopic study of phlogopite synthesized above 600/sup 0/C suggests a disordered Al-Si distribution. Calculations of the P-T locus of the geologically important equilibrium: Phl + 3Qtz = 3En + Sa + H/sub 2/O, using the authors thermochemical data, agree within experimental error with the results of calculations based on the best available phase equilibrium data only if a tetrahedrally disordered phlogopite is assumed. Such calculations are very sensitive to uncertainties in ..delta..H/sup 0/ and ..delta..HG/sup 0/, and reversed phase equilibrium experiments remain essential to obtaining reliable estimates of thermodynamic properties. In contrast to these Al-Si disordered phlogopites, some biotites of low temperature parageneses (<600/sup 0/C) may have substantial Al-Si order. A variable Al-Si distribution has a substantial effect on the configurational entropy and therefore on the free energy of the mica in question. The second structural complication is stacking disorder, which is present in phlogopite synthesized at 650/sup 0/C but not in the 850/sup 0/C sample. The enthalpy difference between these two samples, determined by solution calorimetry, is smaller than the experimental uncertainty of +/- 1.0 kcal mol/sup -1/. Thus there appears to be little driving force for ordering, and micas with disordered stacking sequences may persist in many geologic environments.

  9. Misuse of thermodynamics in the interpretation of isothermal titration calorimetry data for ligand binding to proteins.

    PubMed

    Pethica, Brian A

    2015-03-01

    Isothermal titration calorimetry (ITC) has given a mass of data on the binding of small molecules to proteins and other biopolymers, with particular interest in drug binding to proteins chosen as therapeutic indicators. Interpretation of the enthalpy data usually follows an unsound protocol that uses thermodynamic relations in circumstances where they do not apply. Errors of interpretation include incomplete definitions of ligand binding and equilibrium constants and neglect of the non-ideality of the solutions under study, leading to unreliable estimates of standard free energies and entropies of binding. The mass of reported thermodynamic functions for ligand binding to proteins estimated from ITC enthalpies alone is consequently of uncertain thermodynamic significance and utility. ITC and related experiments to test the protocol assumptions are indicated. A thermodynamic procedure avoiding equilibrium constants or other reaction models and not requiring protein activities is given. The discussion draws attention to the fundamental but neglected relation between the thermodynamic activity and bioactivity of drugs and to the generally unknown thermodynamic status of ligand solutions, which for drugs relates directly to effective therapeutic dosimetry.

  10. Phosphate sorption by three potential filter materials as assessed by isothermal titration calorimetry.

    PubMed

    Lyngsie, Gry; Penn, Chad J; Hansen, Hans C B; Borggaard, Ole K

    2014-10-01

    Phosphorus eutrophication of lakes and streams, coming from drained farmlands, is a serious problem in areas with intensive agriculture. Installation of phosphate (P) sorbing filters at drain outlets may be a solution. The aim of this study was to improve the understanding of reactions involved in P sorption by three commercial P sorbing materials, i.e. Ca/Mg oxide-based Filtralite-P, Fe oxide-based CFH-12 and Limestone in two particle sizes (2-1 mm and 1-0.5 mm), by means of isothermal titration calorimetry (ITC), sorption isotherms, sequential extractions and SEM-EDS. The results indicate that P retention by CFH is due to surface complexation by rapid formation of strong Fe-P bonds. In contrast, retention of P by Filtralite-P and Limestone strongly depends on pH and time and is interpreted due to formation of calcium phosphate precipitate(s). Consequently, CFH can unambiguously be recommended as P retention filter material in drain outlets, whereas the use of Filtralite-P and Limestone has certain (serious) limitations. Thus, Filtralite-P has high capacity to retain P but only at alkaline pH (pH ≥ 10) and P retention by Limestone requires long-time contact and a high ratio between sorbent and sorbate.

  11. Study of coolant activation and dose rates with flow rate and power perturbations in pool-type research reactors

    SciTech Connect

    Mirza, N.M.; Mirza, S.M.; Ahmad, N. )

    1991-12-01

    This paper reports on a computer code using the multigroup diffusion theory based LEOPARD and ODMUG programs that has been developed to calculate the activity in the coolant leaving the core of a pool-type research reactor. Using this code, the dose rates at various locations along the coolant path with varying coolant flow rate and reactor power perturbations are determined. A flow rate decrease from 1000 to 145 m{sup 3}/h is considered. The results indicate that a flow rate decrease leads to an increase in the coolant outlet temperature, which affects the neutron group constants and hence the group fluxes. The activity in the coolant leaving the core increases with flow rate decrease. However, at the inlet of the holdup tank, the total dose rate first increases, then passes through a maximum at {approximately} 500 m{sup 3}/h, and finally decreases with flow rate decrease. The activity at the outlet of the holdup tank is mainly due to {sup 24}Na and {sup 56}Mn, and it increases by {approximately} 2% when the flow rate decreases from 1000 to 145 m{sup 3}/h. In an accidental power rise at constant flow rate, the activity in the coolant increases, and the dose rates at all the points along the coolant path show a slight nonlinear rise as the reactor power density increases.

  12. Miscibility, Crystallization, and Rheological Behavior of Solution Casting Poly(3-hydroxybutyrate)/poly(ethylene succinate) Blends Probed by Differential Scanning Calorimetry, Rheology, and Optical Microscope Techniques

    NASA Astrophysics Data System (ADS)

    Sun, Wei-hua; Qiao, Xiao-ping; Cao, Qi-kun; Liu, Jie-ping

    2010-02-01

    The miscibility and crystallization of solution casting biodegradable poly(3-hydroxybutyrate)/poly(ethylene succinate) (PHB/PES) blends was investigated by differential scanning calorimetry, rheology, and optical microscopy. The blends showed two glass transition temperatures and a depression of melting temperature of PHB with compositions in phase diagram, which indicated that the blend was partially miscible. The morphology observation supported this result. It was found that the PHB and PES can crystallize simultaneously or upon stepwise depending on the crystallization temperatures and compositions. The spherulite growth rate of PHB increased with increasing of PES content. The influence of compositions on the spherulitic growth rate for the partially miscible polymer blends was discussed.

  13. Full text publication rates of studies presented at an international emergency medicine scientific meeting.

    PubMed

    Chan, Jannet W M; Graham, Colin A

    2011-09-01

    The publication rate of full text papers following an abstract presentation at a medical conference is variable, and few studies have examined the situation with respect to international emergency medicine conferences. This retrospective study aimed to identify the publication rate of abstracts presented at the 2006 International Conference on Emergency Medicine (ICEM) held in Halifax, Canada. The full text publication rate was 33.2%, similar to previous emergency medicine meetings. English language barriers may play a role in the low publication rate seen.

  14. Steady State Condition in the Measurement of VO2and VCO2by Indirect Calorimetry.

    PubMed

    Cadena, M; Sacristan, E; Infante, O; Escalante, B; Rodriguez, F

    2005-01-01

    Resting Metabolic Rate (RMR) is computed using VO2and VCO2short time 15-minute window measurement with Indirect Calorimetry (IC) instruments designed with mixing chamber. Steady state condition using a 10% variation coefficient criteria is the main objective to achieve metabolic long time prediction reliability. This study address how susceptible is the steady state VO2, VCO2measurement condition to the clino-orthostatic physiological maneuver. 30 young healthy subjects were analyzed. Only 18 passed the 10% variation coefficient inclusive criteria. They were exposed to 10 minutes clino-stage and 10 minutes orthostage. The hypothesis tests show not statistical significance (p< 0.1) in the average and variance analysis. It is concluded that the steady state is not influenced by the patient position IC test, probably because IC mixing chamber instruments are insensitive to detect a mayor physiological dynamics changes that can modify the steady state definition.

  15. Validation of indirect calorimetry for measurement of energy expenditure in healthy volunteers undergoing pressure controlled non-invasive ventilation support.

    PubMed

    Siirala, Waltteri; Noponen, Tommi; Olkkola, Klaus T; Vuori, Arno; Koivisto, Mari; Hurme, Saija; Aantaa, Riku

    2012-02-01

    The aim of this validation study was to assess the reliability of gas exchange measurement with indirect calorimetry among subjects who undergo non-invasive ventilation (NIV). Oxygen consumption (VO2) and carbon dioxide production (VCO2) were measured in twelve healthy volunteers. Respiratory quotient (RQ) and resting energy expenditure (REE) were then calculated from the measured VO2 and VCO2 values. During the measurement period the subjects were breathing spontaneously and ventilated using NIV. Two different sampling air flow values 40 and 80 l/min were used. The gas leakage from the measurement setup was assessed with a separate capnograph. The mean weight of the subjects was 93 kg. Their mean body mass index was 29 (range 22-40) kg/m2. There was no statistically significant difference in the measured values for VO2, VCO2, RQ and REE during NIV-supported breathing and spontaneous breathing. The change of sampling air flow had no statistically significant effect on any of the above parameters. We found that REE can be accurately measured with an indirect calorimeter also during NIV-supported breathing and the change of sampling air flow does not distort the gas exchange measurement. A higher sampling air flow in indirect calorimetry decreases the possibility for air leakages in the measurement system and increases the reliability of REE measurement.

  16. Aggregation property of glycyrrhizic acid and its interaction with cyclodextrins analyzed by dynamic light scattering, isothermal titration calorimetry, and NMR.

    PubMed

    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.

  17. Interpreting the γ Statistic in Phylogenetic Diversification Rate Studies: A Rate Decrease Does Not Necessarily Indicate an Early Burst

    PubMed Central

    Fordyce, James A.

    2010-01-01

    Background Phylogenetic hypotheses are increasingly being used to elucidate historical patterns of diversification rate-variation. Hypothesis testing is often conducted by comparing the observed vector of branching times to a null, pure-birth expectation. A popular method for inferring a decrease in speciation rate, which might suggest an early burst of diversification followed by a decrease in diversification rate is the γ statistic. Methodology Using simulations under varying conditions, I examine the sensitivity of γ to the distribution of the most recent branching times. Using an exploratory data analysis tool for lineages through time plots, tree deviation, I identified trees with a significant γ statistic that do not appear to have the characteristic early accumulation of lineages consistent with an early, rapid rate of cladogenesis. I further investigated the sensitivity of the γ statistic to recent diversification by examining the consequences of failing to simulate the full time interval following the most recent cladogenic event. The power of γ to detect rate decrease at varying times was assessed for simulated trees with an initial high rate of diversification followed by a relatively low rate. Conclusions The γ statistic is extraordinarily sensitive to recent diversification rates, and does not necessarily detect early bursts of diversification. This was true for trees of various sizes and completeness of taxon sampling. The γ statistic had greater power to detect recent diversification rate decreases compared to early bursts of diversification. Caution should be exercised when interpreting the γ statistic as an indication of early, rapid diversification. PMID:20668707

  18. Building process knowledge using inline spectroscopy, reaction calorimetry and reaction modeling--the integrated approach.

    PubMed

    Tummala, Srinivas; Shabaker, John W; Leung, Simon S W

    2005-11-01

    For over two decades, reaction engineering tools and techniques such as reaction calorimetry, inline spectroscopy and, to a more limited extent, reaction modeling, have been employed within the pharmaceutical industry to ensure safe and robust scale-up of organic reactions. Although each of these techniques has had a significant impact on the landscape of process development, an effective integrated approach is now being realized that combines calorimetry and spectroscopy with predictive modeling tools. This paper reviews some recent advances in the use of these reaction engineering tools in process development within the pharmaceutical industry and discusses their potential impact on the effective application of the integrated approach.

  19. The Physics of the Far-infrared-Radio Correlation. I. Calorimetry, Conspiracy, and Implications

    NASA Astrophysics Data System (ADS)

    Lacki, Brian C.; Thompson, Todd A.; Quataert, Eliot

    2010-07-01

    The far-infrared (FIR) and radio luminosities of star-forming galaxies are linearly correlated over a very wide range in star formation rate, from normal spirals like the Milky Way to the most intense starbursts. Using one-zone models of cosmic ray (CR) injection, cooling, and escape in star-forming galaxies, we attempt to reproduce the observed FIR-radio correlation (FRC) over its entire span. The normalization and linearity of the FRC, together with constraints on the CR population in the Milky Way, have strong implications for the CR and magnetic energy densities in star-forming galaxies. We show that for consistency with the FRC, ~2% of the kinetic energy from supernova explosions must go into high-energy primary CR electrons and that ~10%-20% must go into high-energy primary CR protons. Secondary electrons and positrons are likely comparable to or dominate primary electrons in dense starburst galaxies. We discuss the implications of our models for the magnetic field strengths of starbursts, the detectability of starbursts by Fermi, and CR feedback. Overall, our models indicate that both CR protons and electrons escape from low surface density galaxies, but lose most of their energy before escaping dense starbursts. The FRC is caused by a combination of the efficient cooling of CR electrons (calorimetry) in starbursts and a conspiracy of several factors. For lower surface density galaxies, the decreasing radio emission caused by CR escape is balanced by the decreasing FIR emission caused by the low effective UV dust opacity. In starbursts, bremsstrahlung, ionization, and inverse Compton cooling decrease the radio emission, but they are countered by secondary electrons/positrons and the dependence of synchrotron frequency on energy, both of which increase the radio emission. Our conclusions hold for a broad range of variations in our fiducial model, such as those including winds, different magnetic field strengths, and different diffusive escape times.

  20. Bounds on halo-particle interactions from interstellar calorimetry

    NASA Technical Reports Server (NTRS)

    Chivukula, Sekhar R.; Cohen, Andrew G.; Dimopoulos, Savas; Walker, Terry P.

    1990-01-01

    It is shown that the existence of neutral interstellar clouds constrains the interaction of any particulate dark-matter candidate with atomic hydrogen to be quite small. Even for a halo particle of mass 1 PeV (10 to the 6 GeV), it is shown that the cross section with hydrogen must be smaller than the typical atomic cross section that is expected for a positively charged particle bound to an electron. The argument presented is that if the clouds are in equilibrium, then the rate at which energy is deposited by collisions with dark-matter particles must be smaller than the rate at which the cloud can cool. This argument is used to constrain the interaction cross section of dark matter with hydrogen. Remarks are made on the general viability of charged dark matter. Comments are also made on a bound which derives from the dynamical stability of the halo.

  1. PREFACE: XVth International Conference on Calorimetry in High Energy Physics (CALOR2012)

    NASA Astrophysics Data System (ADS)

    Akchurin, Nural

    2012-12-01

    from Cells to Cities - a Physicist's Search for Quantitative, Unified Theories of Biological and Social Structure and Dynamics,' inspired many interesting questions from the audience both after the talk and throughout the week during informal conversations. Calorimetry is extremely diverse: many different techniques may be employed in building the detector and also in extracting information from it. The topics of the Calorimeter Techniques sessions included high-rate liquid argon calorimeters, SiPM sensors, highly granular digital calorimeters, new crystals, and beam test and simulation results. In these pages, you will find exciting and sometimes contradicting points of view expressed, for example about fully sampling hadronic calorimeters. A rare astronomical event, the Venus transit, coincided with the second day of the conference. The participants enjoyed viewing Venus' trail across the sun with a solar telescope (H-alpha line at 656 nm). In Santa Fe, the interior ingress was at 16:23:04 and reached center at 19:27:04. The last transit occurred in 2004, and the next one will happen in 2117. In 1627, Johannes Kepler published data about the planetary orbits that predicted that Venus would pass directly between earth and the sun in 1631. Unfortunately Kepler died in 1630 and apparently nobody recorded the 1631 transit. The first recorded observation of a transit was in 1638, which Kepler had not predicted. Later, Jeremiah Horracks, an English astronomer, realized Kepler had made an error in his calculations. It was not until the Venus transit observations of 1769 that scientists measured the distance from the earth to the sun to be 95 million miles (actually 93 million miles or 149.7 million kilometers) based on the 1716 triangulation suggestion from Edmund Halley (of comet fame). It's interesting to remember that before the 18th century, one of the most vexing scientific puzzles, not unlike today's Higgs boson quest, was 'How far away is the Sun?' Although natural

  2. Thermometry, calorimetry, and mean body temperature during heat stress.

    PubMed

    Kenny, Glen P; Jay, Ollie

    2013-10-01

    Heat balance in humans is maintained at near constant levels through the adjustment of physiological mechanisms that attain a balance between the heat produced within the body and the heat lost to the environment. Heat balance is easily disturbed during changes in metabolic heat production due to physical activity and/or exposure to a warmer environment. Under such conditions, elevations of skin blood flow and sweating occur via a hypothalamic negative feedback loop to maintain an enhanced rate of dry and evaporative heat loss. Body heat storage and changes in core temperature are a direct result of a thermal imbalance between the rate of heat production and the rate of total heat dissipation to the surrounding environment. The derivation of the change in body heat content is of fundamental importance to the physiologist assessing the exposure of the human body to environmental conditions that result in thermal imbalance. It is generally accepted that the concurrent measurement of the total heat generated by the body and the total heat dissipated to the ambient environment is the most accurate means whereby the change in body heat content can be attained. However, in the absence of calorimetric methods, thermometry is often used to estimate the change in body heat content. This review examines heat exchange during challenges to heat balance associated with progressive elevations in environmental heat load and metabolic rate during exercise. Further, we evaluate the physiological responses associated with heat stress and discuss the thermal and nonthermal influences on the body's ability to dissipate heat from a heat balance perspective.

  3. Caesarean section rates in the Arab region: a cross-national study

    PubMed Central

    JURDI, ROZZET; KHAWAJA, MARWAN

    2006-01-01

    This study had a dual purpose of estimating population- and hospital-based caesarean section rates in 18 Arab countries and examining the association between these rates and important indicators of socioeconomic development. Data on caesarean section were based on the most recent population-based surveys undertaken in each country. Descriptive statistics and bivariate correlation coefficients were used for the analysis. Specifically, Spearman’s rank correlation coefficients were used to analyze the associations between caesarean section rates and important population parameters. Results revealed that four Arab countries had population-based caesarean rates below 5%, while only three countries had rates above 15%. The remaining 11 countries had caesarean rates ranging between 5–15%. Higher hospital-based rates were reported for all countries. Differences in caesarean section rates between private and public hospitals were also noted. Highly significant associations were observed between population caesarean rates and female literacy, percentage urban, infant mortality rate, and the proportion of physicians per 100 000 people. The ‘caesarean section epidemic’ observed in countries of Latin America is not yet evident in the 18 Arab countries examined. Rather, emphasis should be on improving access to appropriate obstetrical interventions in case of complications in a number of countries where rates were well below 5%. PMID:14982888

  4. Control of continuous polyhydroxybutyrate synthesis using calorimetry and flow cytometry.

    PubMed

    Maskow, Thomas; Müller, Susann; Lösche, Andreas; Harms, Hauke; Kemp, Richard

    2006-02-20

    The substrate-carbon flow can be controlled in continuous bioreactor cultures by the medium composition, for example, by the C/N ratio. The carbon distribution is optimal when a maximum fraction flows into the desired product and the residual is just sufficient to compensate for the dilution of the microbial catalyst. Undershooting of the latter condition is reflected immediately by changes in the Gibbs energy dissipation and cellular states. Two calorimetric measurement principles were applied to optimize the continuous synthesis of polyhydroxybutyrate (PHB) by Variovorax paradoxus DSM4065 during growth with constantly increasing supply rates of fructose or toxic phenol. Firstly, the changed slope of the heat production rate in a complete heat balanced bioreactor (CHB) indicated optimum carbon channeling into PHB. The extent of the alteration depended directly on the toxic properties of the substrate. Secondly, a flow through calorimeter was connected with the bioreactor as a "measurement loop." The optimum substrate carbon distribution was indicated by a sudden change in the heat production rate independent of substrate toxicity. The sudden change was explained mathematically and exploited for the long-term control of phenol conversion into PHB. LASER flow cytometry measurements distinguished between subpopulations with completely different PHB-content. Populations grown on fructose preserved a constant ratio of two subpopulations with double and quadruple sets of DNA. Cells grown on phenol comprised a third subpopulation with a single DNA set. Rising phenol concentrations caused this subpopulation to increase. It may thus be considered as an indicator of chemostress.

  5. Association Between Air Temperature and Cancer Death Rates in Florida: An Ecological Study.

    PubMed

    Hart, John

    2015-01-01

    Proponents of global warming predict adverse events due to a slight warming of the planet in the last 100 years. This ecological study tests one of the possible arguments that might support the global warming theory - that it may increase cancer death rates. Thus, average daily air temperature is compared to cancer death rates at the county level in a U.S. state, while controlling for variables of smoking, race, and land elevation. The study revealed that lower cancer death rates were associated with warmer temperatures. Further study is indicated to verify these findings.

  6. 76 FR 28265 - Solicitation of Comment To Assist in Study on Assigned Credit Ratings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-16

    ...The Securities and Exchange Commission (``Commission'') requests public comment to assist it in carrying out a study on, among other matters, the feasibility of establishing a system in which a public or private utility or a self-regulatory organization (``SRO'') assigns nationally recognized statistical rating organizations (``NRSROs'') to determine credit ratings for structured finance......

  7. The Influence of the MPAA's Film Rating System on Motion Picture Attendance: A Pilot Study.

    ERIC Educational Resources Information Center

    Austin, Bruce A.

    A study was undertaken to design and implement an experimental instrument for testing the influence of the Motion Picture Association of America's (MPAA) film rating system on movie attendance. Sixty-five high school students were given synopses of four different fictional films, each of which had been assigned an MPAA rating of G (approved for…

  8. Working While Studying: The Impact of Term-Time Employment on Dropout Rates

    ERIC Educational Resources Information Center

    Hovdhaugen, Elisabeth

    2015-01-01

    There are many possible reasons why students leave university prior to degree completion, and one of the more commonly cited is being employed while studying. This paper analyses the impact of employment status on dropout rates using survival analysis. It finds that employment status does have an impact on dropout rates; students who work full…

  9. Rating Performance Assessments of Students with Disabilities: A Study of Reliability and Bias

    ERIC Educational Resources Information Center

    Mastergeorge, Ann M.; Martinez, Jose Felipe

    2010-01-01

    Inclusion of students with disabilities in district-wide and state assessments is mandated by federal regulations, and teachers sometimes play an important role in rating these students' work. In this study, trained teachers rated student proficiency in performance assessments in language arts and mathematics in third, fifth, and ninth grades. The…

  10. A Mixed Methods Explanatory Study of the Failure/Drop Rate for Freshman STEM Calculus Students

    ERIC Educational Resources Information Center

    Worthley, Mary

    2013-01-01

    In a national context of high failure rates in freshman calculus courses, the purpose of this study was to understand who is struggling, and why. High failure rates are especially alarming given a local environment where students have access to a variety of academic, and personal, assistance. The sample consists of students at Colorado State…

  11. Rating Quality Studies Using Rasch Measurement Theory. Research Report 2013-3

    ERIC Educational Resources Information Center

    Engelhard, George, Jr.; Wind, Stefanie A.

    2013-01-01

    The major purpose of this study is to examine the quality of ratings assigned to CR (constructed-response) questions in large-scale assessments from the perspective of Rasch Measurement Theory. Rasch Measurement Theory provides a framework for the examination of rating scale category structure that can yield useful information for interpreting the…

  12. The 150 Credit-Hour Requirement and CPA Examination Pass Rates--A Four Year Study

    ERIC Educational Resources Information Center

    Briggs, Gary P.; He, Lerong

    2012-01-01

    Debate concerning the minimum educational requirements of certified public accountant (CPA) candidates in the USA has been taking place for decades. This paper compares the sectional pass rates of CPA candidates from jurisdictions requiring 150 credit hours of college study with the pass rates of candidates from jurisdictions not requiring 150…

  13. Energy Policy Act Transportation Rate Study: Final Report on Coal Transportation

    EIA Publications

    2000-01-01

    This is the final in a series of reports prepared for the U.S. Congress by the Secretary of Energy on coal distribution and transportation rates as mandated by Title XIII, Section 1340, Establishment of Data Base and Study of Transportation Rates, of the Energy Policy Act of 1992 (P.L. 102-486).

  14. A Follow-Up Study to Compare Success Rates of Developmental Math Students

    ERIC Educational Resources Information Center

    Woodard, Teresa; Burkett, Sexton

    2010-01-01

    This article presents a study that compared the success rates of students in Arithmetic (MTH 02), Algebra I (MTH 03), and Algebra II (MTH 03) when they were offered at Southwest Virginia Community College (SWCC) for three credits versus five credits. The authors' findings showed no significant differences in the success rates of students who were…

  15. Avalanche correlations in the martensitic transition of a Cu-Zn-Al shape memory alloy: analysis of acoustic emission and calorimetry.

    PubMed

    Baró, Jordi; Martín-Olalla, José-María; Romero, Francisco Javier; Gallardo, María Carmen; Salje, Ekhard K H; Vives, Eduard; Planes, Antoni

    2014-03-26

    The existence of temporal correlations during the intermittent dynamics of a thermally driven structural phase transition is studied in a Cu-Zn-Al alloy. The sequence of avalanches is observed by means of two techniques: acoustic emission and high sensitivity calorimetry. Both methods reveal the existence of event clustering in a way that is equivalent to the Omori correlations between aftershocks in earthquakes as are commonly used in seismology.

  16. Estimating Rates of Motor Vehicle Crashes Using Medical Encounter Data: A Feasibility Study

    DTIC Science & Technology

    2015-11-05

    see Table 3). Figure 6 shows changes in MVC rates across the study period. The DoN as a whole experienced a slight decline in MVC rates of about...duty; M = mean; MVC = motor vehicle crash; SD = standard deviation. Figure 7 displays changes in MVC rates over time for male...rank groups were less than 1 in 100 (E4–E5: 0.7%, E6–E9: 0.6%, officers: 0.5%). Figures 9a and 9b show changes in rates of MVCs among personnel

  17. A study of leakage rates through mine seals in underground coal mines

    PubMed Central

    Schatzel, Steven J.; Krog, Robert B.; Mazzella, Andrew; Hollerich, Cynthia; Rubinstein, Elaine

    2015-01-01

    The National Institute for Occupational Safety and Health conducted a study on leakage rates through underground coal mine seals. Leakage rates of coal bed gas into active workings have not been well established. New seal construction standards have exacerbated the knowledge gap in our understanding of how well these seals isolate active workings near a seal line. At a western US underground coal mine, we determined seal leakage rates ranged from about 0 to 0.036 m3/s for seven 340 kPa seals. The seal leakage rate varied in essentially a linear manner with variations in head pressure at the mine seals. PMID:26322119

  18. Studies of human mutation rates, December 1, 1985--November 30, 1986

    SciTech Connect

    Neel, J.V.

    1985-05-01

    This program seeks to quantify native human mutation rates and to determine how man's activities may affect these rates. The program is divided into six tasks, i.e. The American Indian mutation rate, monitoring populations for frequency of mutation by electrophoresis of blood proteins, application of molecular biological approaches to the detection and study of mutational events in human populations, development of two-dimensional electrophoresis for identification of mutant proteins, co-operative program with the Radiation Effects Research Foundation in Hiroshima and Nagasaki, Japan, and statistical problems associated with the estimation of mutation rates. Progress of each of the above tasks is related in detail. (DT)

  19. Characterization of lipophilic gemcitabine prodrug-liposomal membrane interaction by differential scanning calorimetry.

    PubMed

    Castelli, Francesco; Sarpietro, Maria Grazia; Ceruti, Maurizio; Rocco, Flavio; Cattel, Luigi

    2006-01-01

    Gemcitabine is an anticancer agent rapidly deaminated to the inactive metabolite 2',2'-difluorodeoxyuridine. Its stability as well as bioavailability can be increased by making prodrugs. A series of lipophilic prodrugs of gemcitabine were synthesized by linking the 4-amino group with valeroyl, lauroyl, and stearoyl linear acyl derivatives. We studied, by the differential scanning calorimetry technique, and compared the interaction of pure gemcitabine and its prodrugs with dimyristoylphosphatidylcholine and distearoylphosphatidylcholine vesicles with the aim of demonstrating if the gemcitabine prodrug is more able than the pure gemcitabine to interact with lipid vesicles employed both as model biomembranes and as carriers in the transport of antitumor drugs. These studies, carried out by static and kinetic calorimetric measurements, give evidence that the increase of the prodrug's lipophilic character improves the interaction with lipid bilayers, favoring the absorption through the lipid barriers and allowing the liposomes to work (when the prodrug is inserted inside the vesicles) as a lipophilic carrier which is able to deliver the drug near the cell surface. The use of different prodrugs modified in their lipophilic character, of different kinds of vesicles (multilamellar and unilamellar), and of different kinds of vesicles forming phospholipids permitted us to determine the better equilibrium between in-vesicle solubility and through-vesicle diffusion of the drug, important in the preformulative studies of antitumor carriers based on phospholipid formulations. Such studies suggest that the prodrug lipophilic tail should modulate the transport and the release of gemcitabine inside the cellular compartments, and the efficiency of the liposomal system is related to the length of the prodrug's acyl chain which has to match the phospholipid acyl chain allowing or retarding the migration through the lipid release device.

  20. Capacity fade study of lithium-ion batteries cycled at high discharge rates

    NASA Astrophysics Data System (ADS)

    Ning, Gang; Haran, Bala; Popov, Branko N.

    Capacity fade of Sony US 18650 Li-ion batteries cycled using different discharge rates was studied at ambient temperature. The capacity losses were estimated after 300 cycles at 2 C and 3 C discharge rates and were found to be 13.2 and 16.9% of the initial capacity, respectively. At 1 C discharge rate the capacity lost was only 9.5%. The cell cycled at high discharge rate (3 C) showed the largest internal resistance increase of 27.7% relative to the resistance of the fresh cells. The rate capability losses were proportional with the increase of discharge rates. Half-cell study and material and charge balances were used to quantify the capacity fade due to the losses of primary active material (Li +), the secondary active material (LiCoO 2/C)) and rate capability losses. It was found that carbon with 10.6% capacity loss after 300 cycles dominates the capacity fade of the whole cell at high discharge rates (3 C). A mechanism is proposed which explains the capacity fade at high discharge rates.

  1. Correlation of gene expression and protein production rate - a system wide study

    PubMed Central

    2011-01-01

    Background Growth rate is a major determinant of intracellular function. However its effects can only be properly dissected with technically demanding chemostat cultivations in which it can be controlled. Recent work on Saccharomyces cerevisiae chemostat cultivations provided the first analysis on genome wide effects of growth rate. In this work we study the filamentous fungus Trichoderma reesei (Hypocrea jecorina) that is an industrial protein production host known for its exceptional protein secretion capability. Interestingly, it exhibits a low growth rate protein production phenotype. Results We have used transcriptomics and proteomics to study the effect of growth rate and cell density on protein production in chemostat cultivations of T. reesei. Use of chemostat allowed control of growth rate and exact estimation of the extracellular specific protein production rate (SPPR). We find that major biosynthetic activities are all negatively correlated with SPPR. We also find that expression of many genes of secreted proteins and secondary metabolism, as well as various lineage specific, mostly unknown genes are positively correlated with SPPR. Finally, we enumerate possible regulators and regulatory mechanisms, arising from the data, for this response. Conclusions Based on these results it appears that in low growth rate protein production energy is very efficiently used primarly for protein production. Also, we propose that flux through early glycolysis or the TCA cycle is a more fundamental determining factor than growth rate for low growth rate protein production and we propose a novel eukaryotic response to this i.e. the lineage specific response (LSR). PMID:22185473

  2. Enzyme kinetics determined by single-injection isothermal titration calorimetry.

    PubMed

    Transtrum, Mark K; Hansen, Lee D; Quinn, Colette

    2015-04-01

    The purposes of this paper are (a) to examine the effect of calorimeter time constant (τ) on heat rate data from a single enzyme injection into substrate in an isothermal titration calorimeter (ITC), (b) to provide information that can be used to predict the optimum experimental conditions for determining the rate constant (k2), Michaelis constant (KM), and enthalpy change of the reaction (ΔRH), and (c) to describe methods for evaluating these parameters. We find that KM, k2 and ΔRH can be accurately estimated without correcting for the calorimeter time constant, τ, if (k2E/KM), where E is the total active enzyme concentration, is between 0.1/τ and 1/τ and the reaction goes to at least 99% completion. If experimental conditions are outside this domain and no correction is made for τ, errors in the inferred parameters quickly become unreasonable. A method for fitting single-injection data to the Michaelis-Menten or Briggs-Haldane model to simultaneously evaluate KM, k2, ΔRH, and τ is described and validated with experimental data. All four of these parameters can be accurately inferred provided the reaction time constant (k2E/KM) is larger than 1/τ and the data include enzyme saturated conditions.

  3. Study of Survival Rate After Cardiopulmonary Resuscitation (CPR) in Hospitals of Kermanshah in 2013

    PubMed Central

    Goodarzi, Afshin; Jalali, Amir; Almasi, Afshin; Naderipour, Arsalan; Kalhori, Reza Pourmirza; Khodadadi, Amineh

    2015-01-01

    Background: After CPR, the follow-up of survival rate and caused complications are the most important practices of the medical group. This study was performed aimed at determining the follow-up results after CPR in patients of university hospitals in Kermanshah in 2014. Methods: In this prospective study, 320 samples were examined. A purposive sampling method was used, and data was collected using a researcher-made information form with content and face validity and reliability of r= 0.79. Data was analyzed with STATA9 software and statistical tests, including calculation of the success rate, relative risk (RR), chi-square and Fisher at significance level of P < 0.05. Results: The initial success rate of cardiopulmonary resuscitation was equal to 15.3%, while the ultimate success rate (discharged alive from the hospital) was as 10.6%. The six-month success rate after resuscitation was 8.78% than those who were discharged alive. There were no significant statistical differences between different age groups regarding the initial success rate of resuscitation (P = 0.14), and the initial resuscitation success rate was higher in patients in morning shift (P = 0.02). Conclusion: By the results of study, it is recommended to increase the medical - nursing knowledge and techniques for personnel in the evening and night shifts. Also, an appropriate dissemination of health care staff in working shifts should be done to increase the success rate of CPR procedure. PMID:25560341

  4. PARTICULATE MATTER AND HEART RATE VARIABILITY AMONG ELDERLY RETIREES: THE BALTIMORE 1998 PM STUDY

    EPA Science Inventory

    This study investigates the reported relationship between ambient fine particle pollution and impaired cardiac autonomic control in the elderly. Heart rate variability (HRV) among 56 elderly (mean age 82) nonsmoking residents of a retirement center in Baltimore County, Maryland,...

  5. Study characteristics and recidivism base rates in juvenile sex offender recidivism.

    PubMed

    Caldwell, Michael F

    2010-04-01

    This study reports on the results of a review and meta-analysis of 63 data sets that examine sexual recidivism among juvenile sex offenders. The studies include a total of 11,219 juvenile sex offenders, followed for a weighted mean of 59.4 months (SD = 36.1 months). Recidivism is identified through official records of arrest or conviction. The weighted mean sexual recidivism rate is 7.08% ( SD = 3.9%). The weighted mean rate of general recidivism is 43.4% ( SD = 18.9%). Studies that examine sexual recidivism during adolescence find monthly sexual recidivism rates that are more than 4 times higher than those found in studies that rely only on adult recidivism records. Neither the level of secured placement (community, residential, or secured custody) nor the use of arrest versus conviction as an outcome significantly influences sexual recidivism rates.

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  7. Mathematical analysis for radiometric calorimetry of a radiating sphere

    NASA Technical Reports Server (NTRS)

    Schmid, L. A.

    1982-01-01

    Equations are derived from which the temperature dependence of both the specific heat and the thermal diffusivity of a spherical sample of material can be calculated from observations of the time dependence of the surface temperature and the time-rate of energy loss from the sample as it cools. The derivation takes into account the nonuniformity of the interior temperature field of the sample, and the resulting equations can be applied not only to radiative cooling, but also to any other cooling mechanism that does not violate the assumed spherical symmetry. The analysis excludes change of phase, but it does take thermal expansion into account. To permit the making of estimates necessary for the design of radiative cooling experiments, a universal temperature-time cooling curve is derived for the post-transient cooling regime of a radiating sphere of any size with arbitrary, but constant, thermal parameters.

  8. Monolithic front-end preamplifiers for a broad range of calorimetry applications

    SciTech Connect

    Radeka, V.; Rescia, S.; Manfredi, P.F.; Speziali, V. |

    1993-12-31

    The present paper summarizes the salient results of a research and development activity in the area of low noise preamplifiers for different applications in calorimetry. Design target for all circuits considered here are low noise, ability to cope with broad energy ranges and radiation hardness.

  9. 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...

  10. Protein Unfolding Coupled to Ligand Binding: Differential Scanning Calorimetry Simulation Approach

    ERIC Educational Resources Information Center

    Celej, Maria Soledad; Fidelio, Gerardo Daniel; Dassie, Sergio Alberto

    2005-01-01

    A comprehensive theoretical description of thermal protein unfolding coupled to ligand binding is presented. The thermodynamic concepts are independent of the method used to monitor protein unfolding but a differential scanning calorimetry is being used as a tool for examining the unfolding process.

  11. Subsite binding energies of an exo-polygalacturonase using isothermal titration calorimetry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Thermodynamic parameters for binding of a series of galacturonic acid oligomers to an exo-polygalacturonase, RPG16 from Rhizopus oryzae, were determined by isothermal titration calorimetry. Binding of oligomers varying in chain length from two to five galacturonic acid residues is an exothermic proc...

  12. Isothermal Titration Calorimetry and Macromolecular Visualization for the Interaction of Lysozyme and Its Inhibitors

    ERIC Educational Resources Information Center

    Wei, Chin-Chuan; Jensen, Drake; Boyle, Tiffany; O'Brien, Leah C.; De Meo, Cristina; Shabestary, Nahid; Eder, Douglas J.

    2015-01-01

    To provide a research-like experience to upper-division undergraduate students in a biochemistry teaching laboratory, isothermal titration calorimetry (ITC) is employed to determine the binding constants of lysozyme and its inhibitors, N-acetyl glucosamine trimer (NAG[subscript 3]) and monomer (NAG). The extremely weak binding of lysozyme/NAG is…

  13. Student Learning of Thermochemical Concepts in the Context of Solution Calorimetry.

    ERIC Educational Resources Information Center

    Greenbowe, Thomas J.; Meltzer, David E.

    2003-01-01

    Analyzes student performance on solution calorimetry problems in an introductory university chemistry class. Includes data from written classroom exams for 207 students and an extensive longitudinal interview with a student. Indicates learning difficulties, most of which appear to originate from failure to understand, that net increases and…

  14. Calorimetry exchange program quarterly data report for, January 1989--March 1989

    SciTech Connect

    Lyons, J.E.; McClelland, T.M.

    1996-08-01

    The goals of the calorimetry sample exchange program are to: discuss measurement differences; improve analytical methods; discuss new measurement capabilities; provide data to DOE on measurement capabilities to evaluate shipper-receiver differences; provide standardized materials as necessary; and provide a measurement control program for plutonium analysis. A sample of plutonium dioxide powder is available at each participating site for NDA analysis.

  15. Levitation calorimetry. IV - The thermodynamic properties of liquid cobalt and palladium.

    NASA Technical Reports Server (NTRS)

    Treverton, J. A.; Margrave, J. L.

    1971-01-01

    Some of the thermodynamic properties of liquid cobalt and palladium investigated by means of levitation calorimetry are reported and discussed. The presented data include the specific heats and heats of fusion of the liquid metals, and the emissivities of the liquid metal surfaces.

  16. Calorimetry-Derived Composition Vectors to Resolve Component Raman Spectra in Phospholipid Phase Transitions.

    PubMed

    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.

  17. Development of a water calorimetry-based standard for absorbed dose to water in HDR {sup 192}Ir brachytherapy

    SciTech Connect

    Sarfehnia, Arman; Seuntjens, Jan

    2010-04-15

    Purpose: The aim of this article is to develop and evaluate a primary standard for HDR {sup 192}Ir brachytherapy based on 4 deg. C stagnant water calorimetry. Methods: The absolute absorbed dose to water was directly measured for several different Nucletron microSelectron {sup 192}Ir sources of air kerma strength ranging between 21 000 and 38 000 U and for source-to-detector separations ranging between 25 and 70 mm. The COMSOL MULTIPHYSICS software was used to accurately calculate the heat transport in a detailed model geometry. Through a coupling of the ''conduction and convection'' module with the ''Navier-Stokes incompressible fluid'' module in the software, both the conductive and convective effects were modeled. Results: A detailed uncertainty analysis resulted in an overall uncertainty in the absorbed dose of 1.90%(1{sigma}). However, this includes a 1.5% uncertainty associated with a nonlinear predrift correction which can be substantially reduced if sufficient time is provided for the system to come to a new equilibrium in between successive calorimetric runs, an opportunity not available to the authors in their clinical setting due to time constraints on the machine. An average normalized dose rate of 361{+-}7 {mu}Gy/(h U) at a source-to-detector separation of 55 mm was measured for the microSelectron {sup 192}Ir source based on water calorimetry. The measured absorbed dose per air kerma strength agreed to better than 0.8%(1{sigma}) with independent ionization chamber and EBT-1 Gafchromic film reference dosimetry as well as with the currently accepted AAPM TG-43 protocol measurements. Conclusions: This work paves the way toward a primary absorbed dose to water standard in {sup 192}Ir brachytherapy.

  18. Public Utility Regulatory Policies Act of 1978: Natural Gas Rate Design Study

    SciTech Connect

    1980-05-01

    First, the comments on May 3, 1979 Notice of Inquiry of DOE relating to the Gas Utility Rate Design Study Required by Section 306 of PURPA are presented. Then, comments on the following are included: (1) ICF Gas Utility Model, Gas Utility Model Data Outputs, Scenario Design; (2) Interim Model Development Report with Example Case Illustrations; (3) Interim Report on Simulation of Seven Rate Forms; (4) Methodology for Assessing the Impacts of Alternative Rate Designs on Industrial Energy Use; (5) Simulation of Marginal-Cost-Based Natural Gas Rates; and (6) Preliminary Discussion Draft of the Gas Rate Design Study. Among the most frequent comments expressed were the following: (a) the public should be given the opportunity to review the final report prior to its submission to Congress; (b) results based on a single computer model of only four hypothetical utility situations cannot be used for policy-making purposes for individual companies or the entire gas industry; (c) there has been an unobjective treatment of traditional and economic cost rate structures; the practical difficulties and potential detrimental consequences of economic cost rates are not fully disclosed; and (d) it is erroneous to assume that end users, particularly residential customers, are influenced by price signals in the rate structure, as opposed to the total bill.

  19. Perceived Factors Influencing the Retention Rate of Native American College Students: A Case Study

    ERIC Educational Resources Information Center

    Bergstrom, Tamara Louise

    2012-01-01

    The number of Native Americans entering college is higher now than it has been over the past 40 years; however, the degree completion rate has been less than half that of White students. This research study was a bounded case study of Native American students enrolled in the teacher education program. The purpose of this qualitative case study was…

  20. Assessing Coupled Protein Folding and Binding Through Temperature-Dependent Isothermal Titration Calorimetry.

    PubMed

    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.

  1. Use of differential scanning calorimetry to detect canola oil (Brassica napus L.) adulterated with lard stearin.

    PubMed

    Marikkar, Jalaldeen Mohammed Nazrim; Rana, Sohel

    2014-01-01

    A study was conducted to detect and quantify lard stearin (LS) content in canola oil (CaO) using differential scanning calorimetry (DSC). Authentic samples of CaO were obtained from a reliable supplier and the adulterant LS were obtained through a fractional crystallization procedure as reported previously. Pure CaO samples spiked with LS in levels ranging from 5 to 15% (w/w) were analyzed using DSC to obtain their cooling and heating profiles. The results showed that samples contaminated with LS at 5% (w/w) level can be detected using characteristic contaminant peaks appearing in the higher temperature regions (0 to 70°C) of the cooling and heating curves. Pearson correlation analysis of LS content against individual DSC parameters of the adulterant peak namely peak temperature, peak area, peak onset temperature indicated that there were strong correlations between these with the LS content of the CaO admixtures. When these three parameters were engaged as variables in the execution of the stepwise regression procedure, predictive models for determination of LS content in CaO were obtained. The predictive models obtained with single DSC parameter had relatively lower coefficient of determination (R(2) value) and higher standard error than the models obtained using two DSC parameters in combination. This study concluded that the predictive models obtained with peak area and peak onset temperature of the adulteration peak would be more accurate for prediction of LS content in CaO based on the highest coefficient of determination (R(2) value) and smallest standard error.

  2. Energy policy act transportation study: Interim report on natural gas flows and rates

    SciTech Connect

    1995-11-17

    This report, Energy Policy Act Transportation Study: Interim Report on Natural Gas Flows and Rates, is the second in a series mandated by Title XIII, Section 1340, ``Establishment of Data Base and Study of Transportation Rates,`` of the Energy Policy Act of 1992 (P.L. 102--486). The first report Energy Policy Act Transportation Study: Availability of Data and Studies, was submitted to Congress in October 1993; it summarized data and studies that could be used to address the impact of legislative and regulatory actions on natural gas transportation rates and flow patterns. The current report presents an interim analysis of natural gas transportation rates and distribution patterns for the period from 1988 through 1994. A third and final report addressing the transportation rates and flows through 1997 is due to Congress in October 2000. This analysis relies on currently available data; no new data collection effort was undertaken. The need for the collection of additional data on transportation rates will be further addressed after this report, in consultation with the Congress, industry representatives, and in other public forums.

  3. A study of lower extremity amputation rates in older diabetic South Carolinians.

    PubMed

    Gonsalves, Wanda C; Gessey, Mark E; Mainous, Arch G; Tilley, Barbara C

    2007-02-01

    Several studies have shown that lower extremity non-traumatic amputations for diabetic patients disproportionately affect senior minorities. Our study uses population and Medicare data from the year 2000 to profile the magnitude of this disparity by county in South Carolina and its relation to race, gender, per capita income, and the number of primary care physicians. Data from 1998-2001 is used to investigate trends in amputation rates for the state as a whole and for individual counties. Lower extremity non-traumatic amputation (LEA) rates in black diabetic Medicare patients are more than twice that of White diabetic Medicare patients. In 2000, the three counties with the highest LEA rates for black males were Barnwell (5.06%), Allendale (4.87%), and Florence (4.50%). LEA rates are not related to the number of primary care physicians per 10,000 county residents or per capita income. All gender/race groups saw declines in LEA rates. Although our study could not explain the socioeconomic factors involved, it does mirror other prior studies that show a racial disparity in LEAs. Similarly, men have a greater risk of diabetic non-traumatic LEAs. Interestingly however, having more primary care physicians per 10,000 county residents does not decrease the rate of amputations. Policy makers and insurance brokers may utilize our findings to target the areas of most need for intervention and further studies. Improved adherence to guidelines by primary care physicians, decreasing barriers to health care access, educating patients about the severity of diabetes and its complications, and providing more culturally competent care may lessen the burden of this disability for our minority patients. In the era of "pay for performance", the rate of LEAs as a proxy of poor diabetic care management must clearly improve. Fortunately, the decrease in LEA rates over time as shown in our study is a step in the right direction. However, the decrease is not consistent across all counties

  4. Binding of an Oligomeric Ellagitannin Series to Bovine Serum Albumin (BSA): Analysis by Isothermal Titration Calorimetry (ITC).

    PubMed

    Karonen, Maarit; Oraviita, Marianne; Mueller-Harvey, Irene; Salminen, Juha-Pekka; Green, Rebecca J

    2015-12-16

    A unique series of oligomeric ellagitannins was used to study their interactions with bovine serum albumin (BSA) by isothermal titration calorimetry. Oligomeric ellagitannins, ranging from monomer to heptamer and a mixture of octamer-undecamers, were isolated as individual pure compounds. This series allowed studying the effects of oligomer size and other structural features. The monomeric to trimeric ellagitannins deviated most from the overall trends. The interactions of ellagitannin oligomers from tetramers to octa-undecamers with BSA revealed strong similarities. In contrast to the equilibrium binding constant, enthalpy showed an increasing trend from the dimer to larger oligomers. It is likely that first the macrocyclic part of the ellagitannin binds to the defined binding sites on the protein surface and then the "flexible tail" of the ellagitannin coats the protein surface. The results highlight the importance of molecular flexibility to maximize binding between the ellagitannin and protein surfaces.

  5. The Study of Insurance Premium Rate GIS Mapping Considering the Storm and Flood Hazard Risks

    NASA Astrophysics Data System (ADS)

    Lee, J. S.; Lee, I. S.

    2016-06-01

    Recently, the number of natural disaster occurrence is increasing because of abnormal changes of weather in Korea. In Korea the storm and flood insurance system is in effect to prevent these natural disasters. The national storm and flood insurance Premium rate is very low and the risk of adverse selection resides because of choosing by who lives in high risk area. To solve these problems, the storm and flood insurance rate map are required. In this study, the prototype of storm and flood insurance premium rate map of the Ulsan, Korea was made and the method of GIS analysis for the insurance premium rate calculating and the procedure of the Ulsan storm and flood insurance rate map were researched.

  6. Effects of contingency contracting on study rate and test performance1

    PubMed Central

    Bristol, Marie M.; Sloane, Howard N.

    1974-01-01

    A contingency contracting program designed to increase study rate and subsequent test performance was implemented with a group of undergraduate psychology students. The function of the contingency contracting program in producing increased study rate was evaluated by individual experiments with each student in an experimental contracting group. The overall effect of the program on test performance was assessed by comparing the final scores for the course earned by the experimental group with those earned by two matched control groups. A reversal procedure established that contingency contracting did significantly increase the study rate of students of a wide range of ability. However, it was selectively effective in improving the test performance of below-average students only. Study rate gains in contracted courses did not generalize to noncontracted courses. Self-recording of study time in the absence of scheduled differential consequences did not improve test performance. Study rate under no-consequence conditions varied with test schedule. For both consequence and no-consequence groups, the correlation between study time and final score for the course was only moderate. PMID:4436175

  7. Simulation study of satisfaction rate in the mixed traffic flow with open boundary conditions

    NASA Astrophysics Data System (ADS)

    Bentaleb, Khalid; Lakouari, Noureddine; Ez-Zahraouy, Hamid; Benyoussef, Abdelilah

    2016-08-01

    In this paper, we propose a single-lane cellular automata (CA) traffic model which takes into account the disorder in the length and the maximal speed of the vehicles (i.e. slow and fast) to study the satisfaction rate of the fast vehicles (i.e. the number of vehicles that run with their desired speed) with open boundary conditions in the case of a chain of one entry; where α is the injecting rate of vehicles independent of their nature and β is the extracting rate. The slow vehicles are injected with the conditional probability αs, where 0≤αs=χα≤α and χ is the concentration of the slow vehicles. It is found that for the low value of the injecting rate α and for the high extraction rate β, the satisfaction rate takes higher values. It also depends on the concentration of the slow vehicles injected on the road. Furthermore, we have shown that, in the case when α=β, the satisfaction rate undergoes a transition from the maximal value to the minimal one and it takes a value near to zero in the case of α>β. We have also found that the satisfaction rate depends strongly on the probability of overtaking, also the phase diagrams (α,β) are established for the different values of the slow vehicles concentrations χ.

  8. Rate-based process modeling study of CO{sub 2} capture with aqueous monoethanolamine solution

    SciTech Connect

    Zhang, Y.; Chen, H.; Chen, C.C.; Plaza, J.M.; Dugas, R.; Rochelle, G.T.

    2009-10-15

    Rate-based process modeling technology has matured and is increasingly gaining acceptance over traditional equilibrium-stage modeling approaches. Recently comprehensive pilot plant data for carbon dioxide (CO{sub 2}) capture with aqueous monoethanolamine (MEA) solution have become available from the University of Texas at Austin. The pilot plant data cover key process variables including CO{sub 2} concentration in the gas stream, CO{sub 2} loading in lean MEA solution, liquid to gas ratio, and packing type. In this study, we model the pilot plant operation with Aspen RateSep, a second generation rate-based multistage separation unit operation model in Aspen Plus. After a brief review of rate-based modeling, thermodynamic and kinetic models for CO{sub 2} absorption with the MEA solution, and transport property models, we show excellent match of the rate-based model predictions against the comprehensive pilot plant data and we validate the superiority of the rate-based models over the traditional equilibrium-stage models. We further examine the impacts of key rate-based modeling options, i.e., film discretization options and flow model options. The rate-based model provides excellent predictive capability, and it should be very useful for design and scale-up of CO{sub 2} capture processes.

  9. Quantifying high-affinity binding of hydrophobic ligands by isothermal titration calorimetry.

    PubMed

    Krainer, Georg; Broecker, Jana; Vargas, Carolyn; Fanghänel, Jörg; Keller, Sandro

    2012-12-18

    A fast and reliable quantification of the binding thermodynamics of hydrophobic high-affinity ligands employing a new calorimetric competition experiment is described. Although isothermal titration calorimetry is the method of choice for a quantitative characterization of intermolecular interactions in solution, a reliable determination of a dissociation constant (K(D)) is typically limited to the range 100 μM > K(D) > 1 nM. Interactions displaying higher or lower K(D) values can be assessed indirectly, provided that a suitable competing ligand is available whose K(D) falls within the directly accessible affinity window. This established displacement assay, however, requires the high-affinity ligand to be soluble at high concentrations in aqueous buffer and, consequently, poses serious problems in the study of protein binding involving small-molecule ligands dissolved in organic solvents--a familiar case in many drug-discovery projects relying on compound libraries. The calorimetric competition assay introduced here overcomes this limitation, thus allowing for a detailed thermodynamic description of high-affinity receptor-ligand interactions involving poorly water-soluble compounds. Based on a single titration of receptor into a dilute mixture of the two competing ligands, this competition assay provides accurate and precise values for the dissociation constants and binding enthalpies of both high- and moderate-affinity ligands. We discuss the theoretical background underlying the approach, demonstrate its practical application to metal ion chelation and high-affinity protein-inhibitor interactions, and explore its potential and limitations with the aid of simulations and statistical analyses.

  10. Following mechanical activation of salbutamol sulphate during ball-milling with isothermal calorimetry.

    PubMed

    Gaisford, Simon; Dennison, Mansa; Tawfik, Mahmoud; Jones, Matthew D

    2010-06-30

    Formulation of actives for pulmonary delivery with dry powder inhaler devices frequently requires a particle size reduction step. The high-energy forces imparted to a material during milling, as well as reducing particle size, can cause a significant change in physicochemical properties, in particular mechanical activation of the surface (manifested as generation of amorphous regions) which can affect formulated product performance. It is not clear whether particle size reduction occurs prior to, or concomitantly with, generation of amorphous content. In this study the formation of amorphous content with time in crystalline salbutamol sulphate was quantified with isothermal gas perfusion calorimetry as the sample was ball-milled. The data showed that the most particle size reduction occurred initially (d(0.5) dropping from 12.83+/-0.4 to 4.2+/-0.4 within 5 min). During this time period, no detectable amorphous content was observed. Between 5 and 15 min milling time the particle size distribution remained relatively constant but the amorphous content increased non-linearly with time. After 20 min milling time the particle size increased slightly. The data suggest that particle size reduction occurs initially upon application of a force to the crystal. Once maximum particle size reduction has occurred the crystal absorbs the force being applied and the crystal lattice becomes disordered. After extended milling the conditions in the ball mill (heat and/or humidity) may cause crystallisation of some of the amorphous material resulting in particle-particle fusion. It would appear that the ball-milling process could be optimised to achieve the desired particle size distribution but without any loss of crystalline structure.

  11. New insights into the mechanism of dihydrodipicolinate synthase using isothermal titration calorimetry.

    PubMed

    Muscroft-Taylor, Andrew C; Soares da Costa, Tatiana P; Gerrard, Juliet A

    2010-03-01

    Thermodynamic binding information, obtained via isothermal titration calorimetry (ITC), provides new insights into the binding of substrates, and of allosteric inhibitor interactions of dihydrodipicolinate synthase (DHDPS) from Escherichia coli. DHDPS catalyses the first committed step in (S)-lysine biosynthesis: the Schiff-base mediated aldol condensation of pyruvate with (S)-aspartate semi-aldehyde. Binding studies indicate that pyruvate is a weak binder (0.023 mM) but that (S)-ASA does not interact with the enzyme in the absence of a Schiff-base with pyruvate. These results support the assignment of a ping pong catalytic mechanism in which enthalpically driven Schiff-base formation (DeltaH = -44.5 +/- 0.1 kJ mol(-1)) provides the thermodynamic impetus for pyruvate association. The second substrate, (S)-ASA, was observed to bind to a Schiff-base mimic (DeltaH = -2.8 +/- 0.1 kJ mol(-1)) formed through the reduction of the intermediate pyruvyl-Schiff-base complex. The binding interaction of (S)-lysine was characterised as a cooperative event in which an entropic pre-organisation step (TDeltaS = 17.6 +/- 1.1 kJ mol(-1)) precedes a secondary enthalpic association (DeltaH = -21.6 +/- 0.2 kJ mol(-1)). This allosteric association was determined to be of a mixed competitive nature in which heterotropic ligand cooperativity was observed to subtly influence the binding events. These results offer new insights into the inhibition of this enzyme, a validated antibiotic target.

  12. Practical utility and reliability of whole-room calorimetry in young children.

    PubMed

    Janssen, Xanne; Cliff, Dylan; Okely, Anthony D; Jones, Rachel A; Batterham, Marijka; Ekelund, Ulf; Brage, Søren; Reilly, John J

    2013-05-28

    The use of whole-room calorimetry (WRC) in young children can increase our understanding of children's energy balance. However, studies using WRC in young children are rare due to concerns about its feasibility. To assess the feasibility of WRC in young children, forty children, aged 4–6 years, were asked to follow a graded activity protocol while in a WRC. In addition, six children participated in two additional resting protocols to examine the effect of diet-induced thermogenesis on resting energy expenditure (REE) measures and the reliability of REE measurement. Refusals to participate and data loss were quantified as measures of practical utility, and REE measured after an overnight fast and after a 90-min fast were compared. In addition, both were compared to predicted BMR values using the Schofield equation. Our results showed that thirty (78·9 %) participants had acceptable data for all intensities of the activity protocol. The REE values measured after a 90-min fast (5·07 (SD 1·04) MJ/d) and an overnight fast (4·73 (SD 0·61) MJ/d) were not significantly different from each other (P= 0·472). However, both REE after an overnight fast and a 90-min fast were significantly higher than predicted BMR (3·96 (SD 0·18) MJ/d) using the Schofield equation (P= 0·024 and 0·042, respectively). We conclude that, with a developmentally sensitive approach, WRC is feasible and can be standardised adequately even in 4- to 6-year-old children. In addition, the effect of a small standardised breakfast, approximately 90 min before REE measurements, is likely to be small.

  13. Investigation of Phase Mixing in Amorphous Solid Dispersions of AMG 517 in HPMC-AS Using DSC, Solid-State NMR, and Solution Calorimetry.

    PubMed

    Calahan, Julie L; Azali, Stephanie C; Munson, Eric J; Nagapudi, Karthik

    2015-11-02

    Intimate phase mixing between the drug and the polymer is considered a prerequisite to achieve good physical stability for amorphous solid dispersions. In this article, spray dried amorphous dispersions (ASDs) of AMG 517 and HPMC-as were studied by differential scanning calorimetry (DSC), solid-state NMR (SSNMR), and solution calorimetry. DSC analysis showed a weakly asymmetric (ΔTg ≈ 13.5) system with a single glass transition for blends of different compositions indicating phase mixing. The Tg-composition data was modeled using the BKCV equation to accommodate the observed negative deviation from ideality. Proton spin-lattice relaxation times in the laboratory and rotating frames ((1)H T1 and T1ρ), as measured by SSNMR, were consistent with the observation that the components of the dispersion were in intimate contact over a 10-20 nm length scale. Based on the heat of mixing calculated from solution calorimetry and the entropy of mixing calculated from the Flory-Huggins theory, the free energy of mixing was calculated. The free energy of mixing was found to be positive for all ASDs, indicating that the drug and polymer are thermodynamically predisposed to phase separation at 25 °C. This suggests that miscibility measured by DSC and SSNMR is achieved kinetically as the result of intimate mixing between drug and polymer during the spray drying process. This kinetic phase mixing is responsible for the physical stability of the ASD.

  14. Short term Heart Rate Variability to predict blood pressure drops due to standing: a pilot study

    PubMed Central

    2015-01-01

    Background Standing from a bed or chair may cause a significant lowering of blood pressure (ΔBP), which may have severe consequences such as, for example, falls in older subjects. The goal of this study was to develop a mathematical model to predict the ΔBP due to standing in healthy subjects, based on their Heart Rate Variability, recorded in the 5 minutes before standing. Methods Heart Rate Variability was extracted from an electrocardiogram, recorded from 10 healthy subjects during the 5 minutes before standing. The blood pressure value was measured before and after rising. A mathematical model aiming to predict ΔBP based on Heart Rate Variability measurements was developed using a robust multi-linear regression and was validated with the leave-one-subject-out cross-validation technique. Results The model predicted correctly the ΔBP in 80% of experiments, with an error below the measurement error of sphygmomanometer digital devices (±4.5 mmHg), a false negative rate of 7.5% and a false positive rate of 10%. The magnitude of the ΔBP was associated with a depressed and less chaotic Heart Rate Variability pattern. Conclusions The present study showes that blood pressure lowering due to standing can be predicted by monitoring the Heart Rate Variability in the 5 minutes before standing. PMID:26391336

  15. Relative rate studies of the reactions of chlorine atoms with simple alkanes and the chlorinated methanes

    SciTech Connect

    Wingen, L.; Lee, J.J.; Neavyn, R.

    1995-12-01

    The reactions of chlorine atoms with organics are of interest because atomic chlorine is a potential tropospheric oxidant. Relative rate constants for the reaction of pairs of simple alkanes (ethane/propane, ethane/n-butane, and isobutane/n-butane) and the chlorinated methanes (chloromethane, dichloromethane, and chloroform relative to methane) were measured, using the photolysis of Cl{sub 2} as the source of chlorine atoms and following the loss of the organics by GC-FID. The ratios of the relative rate constants were in excellent agreement with the literature except for ethane/n-butane, where our results are approximately 20% lower than recently published values, and for chloroform/methane, where our value is approximately 50% higher than the values recommended by JPL and JPCRD. Our results will be compard to previously published relative rate studies as well as to the results of absolute rate constant studies, and the differences will be discussed.

  16. Studies Leading to the Development of High-Rate Lithium Sulfuryl Chloride Battery Technology.

    DTIC Science & Technology

    1982-09-01

    greatest attention has been given to the lithium - thionyl chloride (Li/SOC12 ) system. Cells and batteries have been demonstrated with energy densities...Studies Leading to the Development of High-Rate Lithium Sulfuryl Chloride Battery Technology John C. Hall and Mark Koch Gould Research Center, Materials...High-Rate 11182to 33182 Lithium -Sulfuryl Chloride Battery Technology 1_1/82_to_3/31/82 S. PERFORMING ORO. REPORT NUMBER 2 7. AUTHOR(*) S. CONTRACT OR

  17. A study of Mariner 10 flight experiences and some flight piece part failure rate computations

    NASA Technical Reports Server (NTRS)

    Paul, F. A.

    1976-01-01

    The problems and failures encountered in Mariner flight are discussed and the data available through a quantitative accounting of all electronic piece parts on the spacecraft are summarized. It also shows computed failure rates for electronic piece parts. It is intended that these computed data be used in the continued updating of the failure rate base used for trade-off studies and predictions for future JPL space missions.

  18. Normal ranges of heart rate and respiratory rate in children from birth to 18 years: a systematic review of observational studies

    PubMed Central

    Fleming, Susannah; Thompson, Matthew; Stevens, Richard; Heneghan, Carl; Plüddemann, Annette; Maconochie, Ian; Tarassenko, Lionel; Mant, David

    2013-01-01

    Summary Background Although heart rate and respiratory rate are routinely measured in children in acute settings, current reference ranges are not evidence-based. The aim of this study is to derive new centile charts for heart rate and respiratory rate using systematic review data from existing studies, and to compare these with existing international ranges. Methods We searched MEDLINE, EMBASE, and CINAHL to April 2009, and reference lists to identify studies which had measured heart rate and/or respiratory rate in normal children between birth and 18 years of age. We used a non-parametric kernel regression method to create centile charts for heart rate and respiratory rate with respect to age. We compared existing reference ranges with those derived from the centile charts. Findings We included 69 studies, 59 of which provided data on the heart rate of 143,346 children, and 20 on the respiratory rate of 3,881 children. Our new centile charts demonstrate the decline in respiratory rate from birth to early adolescence, with the steepest decline apparent in infants under two years; decreasing from a median of 44 breaths/minutes at birth to 26 breaths/minute at the age of two. The heart rate centile chart demonstrates a small peak at one month of age. The median heart rate increases from 127 beats/minute at birth to a maximum of 145 beats/minute at approximately one month of age, before decreasing to 113 beats/minute by the age of two. Comparison of the centile charts with existing published reference ranges for heart rate and respiratory rate show marked disagreement with the centile charts, with limits from published ranges frequently exceeding the 99th and 1st centiles, or crossing the median. Interpretation Our review shows that existing international guidelines for heart rate and respiratory rate in children are not based on evidence. We have created new centile charts based on a systematic review of studies which have measured these vital signs in normal

  19. The colligative properties of fruit juices by photopyroelectric calorimetry

    NASA Astrophysics Data System (ADS)

    Frandas, A.; Surducan, V.; Nagy, G.; Bicanic, D.

    1999-03-01

    The photopyroelectric method was used to study the depression of freezing point in juices prepared from selected apple and orange juice concentrates. By using the models for real solutions, the effective molecular weight of the dissolved solids was obtained. The acids concentration in the fruit juice is reflected both in the equivalent molecular weight (by lowering it) and in the interaction coefficients b and C. Using the data for the molecular weight and the characteristic coefficients, prediction curves for the samples investigated can be used in practice. Freezing point depression can also be used as an indicator of the degree of spoilage of fruit juices.

  20. A Cross-National Study of the Relationship between Elderly Suicide Rates and Urbanization

    ERIC Educational Resources Information Center

    Shah, Ajit

    2008-01-01

    There is mixed evidence of a relationship between suicide rates in the general population and urbanization, and a paucity of studies examining this relationship in the elderly. A cross-national study with curve estimation regression model analysis, was undertaken to examine the a priori hypothesis that the relationship between elderly suicide…