Science.gov

Sample records for calorimetry dsc experiments

  1. 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.

  2. 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).

  3. 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

  4. 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)

  5. 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.

  6. Recent advances and potential applications of modulated differential scanning calorimetry (mDSC) in drug development.

    PubMed

    Knopp, Matthias Manne; Löbmann, Korbinian; Elder, David P; Rades, Thomas; Holm, René

    2016-05-25

    Differential scanning calorimetry (DSC) is frequently the thermal analysis technique of choice within preformulation and formulation sciences because of its ability to provide detailed information about both the physical and energetic properties of a substance and/or formulation. However, conventional DSC has shortcomings with respect to weak transitions and overlapping events, which could be solved by the use of the more sophisticated modulated DSC (mDSC). mDSC has multiple potential applications within the pharmaceutical field and the present review provides an up-to-date overview of these applications. It is aimed to serve as a broad introduction to newcomers, and also as a valuable reference for those already practising in the field. Complex mDSC was introduced more than two decades ago and has been an important tool for the quantification of amorphous materials and development of freeze-dried formulations. However, as discussed in the present review, a number of other potential applications could also be relevant for the pharmaceutical scientist.

  7. Prediction of the self-accelerating decomposition temperature (SADT) for liquid organic peroxides from differential scanning calorimetry (DSC) measurements.

    PubMed

    Malow, M; Wehrstedt, K D

    2005-04-11

    We present a prediction (estimation, calculation, screening) method for the estimation of the self-accelerating decomposition temperature (SADT) for liquid organic peroxides from differential scanning calorimetry (DSC) measurements based on the concepts of thermal explosion theory originally introduced by Semonov which are adopted to our problem assuming nth-order reaction kinetics. For the peroxides under investigation, we demonstrate good agreement with the experimental SADT. This method can be used as a quick and easy applicable method for the estimation of the critical temperatures.

  8. 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.

  9. Characterization of a Friction Stir Weld in Aluminum Alloy 7055 Using Microhardness, Electrical Conductivity, and Differential Scanning Calorimetry (DSC)

    NASA Astrophysics Data System (ADS)

    Bush, Ralph; Kiyota, Michelle; Kiyota, Catherine

    2016-07-01

    Optical microscopy, microhardness, electrical conductivity, and differential scanning calorimetry (DSC) were used to characterize the microstructure, hardness, and precipitate structure as a function of position in a friction stir weld, naturally aged for 10 years, in aluminum alloy 7055. Results are shown for the as-welded/naturally aged condition and for a weld that was post-aged using a -T76 regimen. The grain structure and microhardness results reveal the expected central recrystallized region, a thermo-mechanical affected zone (TMAZ), and heat-affected zone (HAZ) with typical changes in microhardness. DSC scans for the as-welded/naturally aged condition indicate a precipitate structure similar to that of a naturally aged condition in the central recrystallized region. Maximum precipitate coarsening and overaging occurs near the TMAZ/HAZ boundary with reduced precipitate dissolution and coarsening as the distance from the weld increases. The post-weld aging resulted in the transformation of GP zones to more stable precipitates plus coarsening of the more stable η' and η precipitates. A combination of DSC testing and CALPHAD calculations allowed calculation of precipitate volume fraction in the HAZ. The precipitate volume fraction decreased monotonically from 0.052 in the baseline material to 0.044 at the TMAZ/HAZ interface.

  10. Use of Differential Scanning Calorimetry (DSC) in the Characterization of EPDM/PP Blends

    NASA Astrophysics Data System (ADS)

    Stelescu, Maria Daniela; Airinei, Anton; Grigoras, Cristian; Niculescu-Aron, Ileana-Gabriela

    2010-12-01

    New polyolefinic thermoplastic elastomers based on the ethylene-propylene-diene monomer (EPDM) and polypropylene (PP) containing an EPDM elastomer of the last generation (Nordel NDR 47130), obtained by polymerization in the gaseous phase with metallocene catalysis, were prepared and characterized. The melting and crystallization behavior of these blends was investigated by differential scanning calorimetry. It is observed that the melting temperature, crystallization temperature, and crystallinity degree increase with an increase of PP loading. The influence of the blend composition on the physico-mechanical characteristics was discussed using statistical processing of the experimental data. Two compatibilizing procedures were utilized to improve the physico-mechanical characteristics of the samples: an addition method using different compatibilizing agents and dynamical vulcanization with three types of crosslinking systems. Significant improvements of the tensile strength and tear strength were noted by dynamic crosslinking, and the best results were obtained using a crosslinking system based on phenolic resin and tin chloride.

  11. Anisotropic-isotropic transition of solutions of cellulose derivatives: a DSC study. [Differential scanning calorimetry

    SciTech Connect

    Navard, P.; Haudin, J.M.; Dayan, S.; Sixou, P.

    1983-01-01

    Cellulose acetate (CA)/trifluoroacetic acid (TFA), cellulose triacetate (CTA)/trifluoroacetic acid, and hydroxypropylcellulose (HPC)/water solutions are able to develop liquid crystalline (cholesteric) order above a certain polymer concentration C/sup **/. When the polymer concentration C is smaller than C/sup **/, no peak is recorded on a DSC trace upon heating. When C>C/sup **/, a well-defined peak for CA/TFA appears at a temperature T/sub t/. This peak is attributed to the anisotropic-isotropic phase transition. The origin and nature of this peak are discussed in the light of available theories. A T/sub t/-C phase diagram is plotted. For CTA/TFA solutions, one or two peaks arise, depending onpolymer concentration. The peak at the higher temperature is attributed to the anisotropic-isotropic transition, and the peak at the lower temperature to the destruction of a ''gel-like'' phase. HPC/water solutions have a very different behavior. Upon heating, they are transformed into a turbid phase regardless of the concentration. 22 references, 11 figures, 1 table.

  12. Differential scanning calorimetry (DSC) as a tool for probing the reactivity of polyynes relevant to hexadehydro-Diels-Alder (HDDA) cascades.

    PubMed

    Woods, Brian P; Hoye, Thomas R

    2014-12-19

    The differential scanning calorimetry (DSC) behavior of a number of alkyne-rich compounds is described. The DSC trace for each compound exhibits an exothermic event at a characteristic onset temperature. For the tri- and tetraynes whose [4 + 2] HDDA reactivity in solution has been determined, these onset temperatures show a strong correlation with the cyclization activation energy. The studies reported here exemplify how the data available through this operationally simple analytical technique can give valuable insights into the thermal behavior of small molecules.

  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. 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:

  15. 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.

  16. Solution Calorimetry Experiments for Physical Chemistry.

    ERIC Educational Resources Information Center

    Raizen, Deborah A.; And Others

    1988-01-01

    Presents two experiments: the first one measures the heat of an exothermic reaction by the reduction of permanganate by the ferris ion; the second one measures the heat of an endothermic process, the mixing of ethanol and cyclohexane. Lists tables to aid in the use of the solution calorimeter. (MVL)

  17. 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

  18. 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.

  19. Correlating DSC and X-Ray Measurements Of Crystallinity

    NASA Technical Reports Server (NTRS)

    Yen, Shiao-Ping S.; Lowry, Lynn E.; Bankston, Clyde P.

    1991-01-01

    Experiment demonstrated approximate linear correlation between degree of crystallinity of multiphase polymer (as calculated from x-ray diffraction measurements) and heat of fusion of polymer (as calculated from differential scanning calorimetry (DSC) measurements). Correlation basis of simple new technique for estimating degree of crystallinity of specimens of polymer from DSC measurements alone.

  20. Simultaneous TG/DSC (thermogravimetry/differential scanning calorimetry) and TG/MS (thermogravimetry/mass spectrometry) analyses of polymeric and energetic materials

    SciTech Connect

    Whitaker, R B; Brown, C R; Chang, C; McDaniel, J A; Shell, T L

    1987-01-01

    The utility of simultaneous thermal analysis techniques, such as TG/DSC and TG/MS, has been demonstrated for both energetic and polymeric materials. TG/DSC can assist in elucidating reaction mechanisms and determining weight losses for endothermic transitions which precede decomposition of energetic materials. The endothermic and exothermic nature of decomposition processes can be defined by TG/DSC and the decomposition products identified by TG/MS.

  1. 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.

  2. 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.

  3. Monitoring of Pentoxifylline Thermal Behavior by Novel Simultaneous Laboratory Small and Wide X-Ray Scattering (SWAXS) and Differential Scanning Calorimetry (DSC).

    PubMed

    Hodzic, Aden; Kriechbaum, Manfred; Schrank, Simone; Reiter, Franz

    2016-01-01

    The thermal and structural evolutions associated to active pharmaceutical ingredient (API) purity are monitored using a laboratory instrument (S3-MicroCaliX) allowing simultaneous time-resolved X-ray scattering at both wide and small angles (SWAXS) as a function of temperature. This is performed simultaneously with differential scanning calorimetric (DSC) that is carried out in the same apparatus at scanning rate of 2 K/min on the same sample in the range from 20° to 200°C. We have studied simultaneous thermal and structural properties of pentoxifylline, as an active pharmaceutical ingredient (API), for its purity quality control. We have found a satisfying API purity, due to obtained melting temperature and enthalpy values, which are in a well agreement with literature. We have also found that the combination of these techniques allows the thermal monitoring of scanning rates of 2 K/min, continuously without the need for static thermal equilibration, particularly for X-ray spectra. Hence, DSC and SWAXS allowing better identification of the structural thermal events recorded by following of the phase transitions simultaneously. This interpretation is much better possible when X-ray scattering at small and wide angles is coupled with DSC from the same sample. Hence, as a laboratory tool, the method presents a reproducible thermal and crystallographic API purity quality control of non-complex samples, as crucial information for pharmaceutical technology.

  4. Application of differential scanning calorimetry (DSC), HPLC and pNMR for interpretation primary crystallisation caused by combined low and high melting TAGs.

    PubMed

    Saadi, Sami; Ariffin, Abdul Azis; Ghazali, Hasanah Mohd; Miskandar, Mat Sahri; Boo, Huey Chern; Abdulkarim, Sabo Mohammed

    2012-05-01

    The main goal of the present work was to assess the mechanism of crystallisation, more precisely the dominant component responsible for primary crystal formations and fat agglomerations. Therefore, DSC results exhibited significant effect on temperature transition; peak sharpness and enthalpy at palm stearin (PS) levels more than 40wt.%. HPLC data demonstrated slight reduction in the content of POO/OPO at PS levels less than 40wt.%, while the excessive addition of PS more than 40wt.% increased significantly PPO/POP content. The pNMR results showed significant drop in SFC for blends containing PS less than 40wt.%, resulting in low SFC less than 15% at body temperature (37°C). Moreover, the values of viscosity (η) and shear stress (τ) at PS levels over 40wt.% expressed excellent internal friction of the admixtures. All the data reported indicate that PPO/POP was the major component of primary nucleus developed. In part, the levels of PS should be less than 40wt.%, if these blends are designed to be used for margarine production.

  5. 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…

  6. Melting, crystallization and storage stability of virgin coconut oil and its blends by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR).

    PubMed

    Srivastava, Yashi; Semwal, Anil Dutt; Sajeevkumar, Vallayil Appukuttan; Sharma, G K

    2017-01-01

    The blends were prepared of virgin coconut oil with refined soyabean oil (VCO-RSOY) and refined safflower oil (VCO-RSAFF). Blending with VCO improved the fatty acid composition which increased the shelf stability of 20:80 VCO-RSOY and VCO-RSAFF up to 12 months in different packaging systems such as low density polyethylene, linear low density polyethylene, metalized polyester pouches, polyethylene teteraphthalate, high density polyethylene (HDPE), Amber HDPE bottle. The specific spectral regions of FTIR proved to be very useful for the determination of adulteration as well as for the study of oxidation process. Band shifts observed at 3008, 1652, 1397, 1097, 912 and 845 cm(-1) have been used to differentiate RSAFF from VCO. VCO spectrums did not have these chemical shifts. Further the spectrum of RSOY showed same band shifts as RSAFF except 1652, 1397, 869.6 and 845 cm(-1). Differential Scanning Calorimetry provided useful information regarding the nature of thermodynamic changes related to physical state of vegetable oil. The physical state changes included melting and crystallization events which require the intake and release of energy.

  7. Some considerations on the vibrational environment of the DSC-DCMIX1 experiment onboard ISS

    NASA Astrophysics Data System (ADS)

    Jurado, R.; Gavaldà, Jna.; Simón, M. J.; Pallarés, J.; Laverón-Simavilla, A.; Ruiz, X.; Shevtsova, V.

    2016-12-01

    The present work attempts to characterize the accelerometric environment of the DSC-DCMIX1 thermodiffusion experiment carried out in the International Space Station, from November 7th 2011 until January 16th 2012. Quasi-steady and vibrational/transient data coming from MAMS and SAMS2 sensors have been downloaded from the database of the PIMS NASA website. To be as exhaustive as possible, simultaneous digital signals coming from different SAMS2 sensors located in the Destiny and Columbus modules have also been considered. In order to detect orbital adjustments, dockings, undockings, as well as, quiescent periods, when the experiment runs were active, we have used the quasi-steady eight hours averaged (XA, YA and ZA) acceleration functions as well as the eight hours RMS ones. To determine the spectral contents of the different signals the Thomson multitaper and Welch methods have been used. On the other hand, to suppress the high levels of noise always existing in the raw SAMS2 signals, denoising techniques have been preferred for comparative reboostings considerations. Finally, the RMS values for specific 1/3 octave frequency bands showed that the International Space Station vibratory limit requirements have not been totally accomplished during both quiescent periods and strong disturbances, specially in the low frequency range.

  8. Laboratory Annealing Experiments Of Refractory Silicate Grain Analogs Using Differential Scanning Calorimetry

    NASA Technical Reports Server (NTRS)

    Kimura, Yuki; Nuth, Joseph A., III; Tsukamota, Katsuo; Kaito, Chihiro

    2010-01-01

    Exothermic reactions during the annealing of laboratory synthesized amorphous magnesium-bearing silicate particles used as grain analogs of cosmic dust were detected by differential scanning calorimetry (DSC) in air. With infrared spectroscopy and transmission electron microscopy, we show that cosmic dust could possibly undergo fusion to larger particles, with oxidation of magnesium silicide and crystallization of forsterite as exothermic reactions in the early solar system. The reactions begin at approximately 425, approximately 625, and approximately 1000 K, respectively, and the reaction energies (enthalpies) are at least 727, 4151, and 160.22 J per gram, respectively. During the crystallization of forsterite particles, the spectral evolution of the 10 micrometer feature from amorphous to crystalline was observed to begin at lower temperature than the crystallization temperature of 1003 K. During spectral evolution at lower temperature, nucleation and/or the formation of nanocrystallites of forsterite at the surface of the grain analogs was observed.

  9. 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.

  10. Effect of milling on DSC thermogram of excipient adipic acid.

    PubMed

    Ng, Wai Kiong; Kwek, Jin Wang; Yuen, Aaron; Tan, Chin Lee; Tan, Reginald

    2010-03-01

    The purpose of this research was to investigate why and how mechanical milling results in an unexpected shift in differential scanning calorimetry (DSC) measured fusion enthalpy (Delta(fus)H) and melting point (T(m)) of adipic acid, a pharmaceutical excipient. Hyper differential scanning calorimetry (hyper-DSC) was used to characterize adipic acid before and after ball-milling. An experimental study was conducted to evaluate previous postulations such as electrostatic charging using the Faraday cage method, crystallinity loss using powder X-ray diffraction (PXRD), thermal annealing using DSC, impurities removal using thermal gravimetric analysis (TGA) and Karl Fischer titration. DSC thermograms showed that after milling, the values of Delta(fus)H and T(m) were increased by approximately 9% and 5 K, respectively. Previous suggestions of increased electrostatic attraction, change in particle size distribution, and thermal annealing during measurements did not explain the differences. Instead, theoretical analysis and experimental findings suggested that the residual solvent (water) plays a key role. Water entrapped as inclusions inside adipic acid during solution crystallization was partially evaporated by localized heating at the cleaved surfaces during milling. The correlation between the removal of water and melting properties measured was shown via drying and crystallization experiments. These findings show that milling can reduce residual solvent content and causes a shift in DSC results.

  11. 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.

  12. Identification of thermal effects involved in DSC experiment on Al-Cu-Mg-Ag alloys with high Cu:Mg ratio

    NASA Astrophysics Data System (ADS)

    Zhang, Jian-Bo; Zhang, Yong-An; Zhu, Bao-Hong; Wang, Feng; Li, Zhi-Hui; Li, Xi-Wu; Xiong, Bai-Qing

    2011-12-01

    Precipitation reactions in the differential scanning calorimetry (DSC) of an Al-Cu-Mg-Ag alloy were identified by analyzing the results from hardness test, electrical conductivity test, and transmission electron microscope (TEM) examination. It is discovered that thermal effects can be identified through selected area electron diffraction and bright-field images. The reaction peaks around 171, 231, and 276°C can be attributed to a structural rearrangement of coherent zones, to the precipitation of Ω phases, and to the precipitation of Ω and θ' and possible combination with the transition of θ'→θ, respectively. In addition, the hardness and electrical conductivity of the alloy change proportionately with the progression of reactions during the heating process. This phenomenon can be attributed to the evolution of the microstructure.

  13. Single-experiment displacement assay for quantifying high-affinity binding by isothermal titration calorimetry.

    PubMed

    Krainer, Georg; Keller, Sandro

    2015-04-01

    Isothermal titration calorimetry (ITC) is the gold standard for dissecting the thermodynamics of a biomolecular binding process within a single experiment. However, reliable determination of the dissociation constant (KD) from a single titration is typically limited to the range 100 μM>KD>1 nM. Interactions characterized by a lower KD can be assessed indirectly by so-called competition or displacement assays, provided that a suitable competitive ligand is available whose KD falls within the directly accessible window. However, this protocol is limited by the fact that it necessitates at least two titrations to characterize one high-affinity inhibitor, resulting in considerable consumption of both sample material and time. Here, we introduce a fast and efficient ITC displacement assay that allows for the simultaneous characterization of both a high-affinity ligand and a moderate-affinity ligand competing for the same binding site on a receptor within a single experiment. The protocol is based on a titration of the high-affinity ligand into a solution containing the moderate-affinity ligand bound to the receptor present in excess. The resulting biphasic binding isotherm enables accurate and precise determination of KD values and binding enthalpies (ΔH) of both ligands. We discuss the theoretical background underlying the approach, demonstrate its practical application to metal ion chelation, explore its potential and limitations with the aid of simulations and statistical analyses, and elaborate on potential applications to protein-inhibitor interactions.

  14. Rapid characterization of folding and binding interactions with thermolabile ligands by DSC.

    PubMed

    Harkness, R W; Slavkovic, S; Johnson, P E; Mittermaier, A K

    2016-11-10

    Differential scanning calorimetry (DSC) is a powerful technique for measuring tight biomolecular interactions. However, many pharmaceutically relevant ligands are chemically unstable at the high temperatures used in DSC analyses. Thus, measuring binding interactions is challenging because the concentrations of ligands and thermally-converted products are constantly changing within the calorimeter cell. Using experimental data for two DNA aptamers that bind to the thermolabile ligand cocaine, we present a new global fitting analysis that yields the complete set of folding and binding parameters for the initial and final forms of the ligand from a pair of DSC experiments, while accounting for the thermal conversion. Furthermore, we show that the rate constant for thermolabile ligand conversion may be obtained with only one additional DSC dataset.

  15. 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.

  16. 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.

  17. 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…

  18. Neutron monitoring and electrode calorimetry experiments in the HIP-1 Hot Ion Plasma

    NASA Technical Reports Server (NTRS)

    Reinmann, J. J.; Layman, R. W.

    1977-01-01

    Results are presented for two diagnostic procedures on HIP-1: neutron diagnostics to determine where neutrons originated within the plasma discharge chamber and electrode calorimetry to measure the steady-state power absorbed by the two anodes and cathodes. Results are also reported for a hot-ion plasma formed with a continuous-cathode rod, one that spans the full length of the test section, in place of the two hollow cathodes. The outboard neutron source strength increased relative to that at the midplane when (1) the cathode tips were moved farther outboard, (2) the anode diameters were increased, and (3) one of the anodes was removed. The distribution of neutron sources within the plasma discharge chamber was insensitive to the division of current between the two cathodes. For the continuous cathode, increasing the discharge current increased the midplane neutron source strength relative to the outboard source strength. Each cathode absorbed from 12 to 15 percent of the input power regardless of the division of current between the cathodes. The anodes absorbed from 20 to 40 percent of the input power. The division of power absorption between the anodes varied with plasma operating conditions and electrode placement.

  19. 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.

  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. Gelatinisation kinetics of corn and chickpea starches using DSC, RVA, and dynamic rheometry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The gelatinisation kinetics (non-isothermal) of corn and chickpea starches at different heating rates were calculated using differential scanning calorimetry (DSC), rapid visco analyser (RVA), and oscillatory dynamic rheometry. The data obtained from the DSC thermogram and the RVA profiles were fitt...

  2. Thermodynamic signature of substrates and substrate analogs binding to human blood group B galactosyltransferase from isothermal titration calorimetry experiments.

    PubMed

    Sindhuwinata, Nora; Grimm, Lena L; Weißbach, Sophie; Zinn, Sabrina; Munoz, Eva; Palcic, Monica M; Peters, Thomas

    2013-10-01

    It has been observed earlier that human blood group B galactosyltransferase (GTB) hydrolyzes its donor substrate UDP-Galactose (UDP-Gal) in the absence of acceptor substrate, and that this reaction is promoted by the presence of an acceptor substrate analog, α-L-Fuc-(1,2)-β-D-3-deoxy-Gal-O-octyl (3DD). This acceleration of enzymatic hydrolysis of UDP-Gal was traced back to an increased affinity of GTB toward the donor substrate in the presence of 3DD. Herein, we present new thermodynamic data from isothermal titration calorimetry (ITC) on the binding of donor and acceptor substrates and analogs to GTB. ITC data are supplemented by surface plasmon resonance and STD-NMR titration experiments. These new data validate mutual allosteric control of binding of donor and acceptor substrates to GTB. It is of note that ITC experiments reveal significant differences in enthalpic and entropic contributions to binding of the natural donor substrate UDP-Gal, when compared with its analog UDP-Glucose (UDP-Glc). This may reflect different degrees of ordering of an internal loop (amino acids 176-194) and the C-terminus (amino acids 346-354), which close the binding pocket on binding of UDP-Gal or UDP-Glc. As both ligands have rather similar dissociation constants KD and almost identical modes of binding this finding is unexpected. Another surprising finding is that an acceptor analog, α-L-Fuc-(1,2)-β-D-3-amino-3-deoxy-Gal-O-octyl (3AD) as well as the constituent monosaccharide β-D-3-amino-3-deoxy-Gal-O-octyl (3AM) effectively inhibit enzymatic hydrolysis of UDP-Gal. This is unexpected, too, because in analogy to the effects of 3DD one would have predicted acceleration of enzymatic hydrolysis of UDP-Gal. It is difficult to explain these observations based on structural data alone. Therefore, our results highlight that there is an urgent need of experimental studies into the dynamic properties of GTB.

  3. Dipolar reorientations in amorphous nimesulide: a TSDC and DSC study.

    PubMed

    Ramos, Joaquim J Moura; Diogo, Hermínio P

    2016-05-10

    The experimental techniques of differential scanning calorimetry (DSC) and thermally stimulated depolarization currents (TSDC) were used to study the thermal behavior of the pharmaceutical drug nimesulide and its slow molecular mobility in the amorphous solid state. The glass forming ability, the glass stability and the tendency for crystallization from the equilibrium melt were investigated by DSC. The general kinetic features of the main relaxation, including the dynamic fragility, were studied by both experimental techniques. The TSDC study of the secondary relaxations did not disclose fast modes. However slow modes were detected, that were ascribed to the Johari - Goldstein relaxation on the basis of an aging study.

  4. Determination of the oxidative stability by DSC of vegetable oils from the Amazonian area.

    PubMed

    Pardauil, Juliana J R; Souza, Luiz K C; Molfetta, Fábio A; Zamian, José R; Rocha Filho, Geraldo N; da Costa, C E F

    2011-05-01

    Differential scanning calorimetry (DSC) and a Rancimat method apparatus were applied to evaluate the oxidative stability of buriti pulp oil (Mauritia flexuosa Mart), rubber seed oil (Hevea brasiliensis), and passion fruit oil (Passiflora edulis). The Rancimat measurements taken for the oxidative induction times were performed under isothermal conditions at 100°C and in an air atmosphere. The DSC technique involved the oxidation of oil samples in an oxygen-flow DSC cell. The DSC cell temperature was set at five different isothermal temperatures: 100, 110, 120, 130 and 140°C. During the oxidation reaction, an increase in heat was observed as a sharp exothermic curve. The value T(0) represents the oxidative induction time, which is determined from the downward extrapolated DSC oxidative curve verses the time axis. These curves indicate a good correlation between the DSC T(0) and oxidative stability index (OSI) values. The DSC method is useful because it consumes less time and less sample.

  5. 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.

  6. DSC of human hair: a tool for claim support or incorrect data analysis?

    PubMed

    Popescu, C; Gummer, C

    2016-10-01

    Differential scanning calorimetry (DSC) data are increasingly used to substantiate product claims of hair repair. Decreasing peak temperatures may indicate structural changes and chemical damage. Increasing the DSC, wet peak temperature is, therefore, often considered as proof of hair repair. A detailed understanding of the technique and hair structure indicates that this may not be a sound approach. Surveying the rich literature on the use of dynamic thermal analysis (DTA) and differential scanning calorimetry (DSC) for the analyses of human hair and the effect of cosmetic treatments, we underline some of the problems of hair structure and data interpretation. To overcome some of the difficulties of data interpretation, we advise that DSC acquired data should be supported by other techniques when used for claim substantiation. In this way, one can provide meaningful interpretation of the hair science and robust data for product claims support.

  7. 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.

  8. Determination of the solubility of crystalline low molar mass compounds in polymers by differential scanning calorimetry.

    PubMed

    Rager, Timo

    2014-06-01

    A mathematical equation has been derived to calculate the liquidus for a binary system consisting of an amorphous polymer and a crystalline low molar mass compound. The experimental input to this equation is an interaction enthalpy, which is derived from the variation of the melting enthalpy with composition in differential scanning calorimetry (DSC) experiments. The predictive power of the equation has been tested with mixtures of acetylsalicylic acid, carbamazepine, or intraconazole with poly(ethylene glycol) as well as mixtures of carbamazepine with poly(acrylic acid), poly(hydroxystyrene), or poly(vinylpyrrolidone). It has been confirmed that the evaluation of the melting enthalpy in DSC is a suitable method to identify the preferred solute-polymer combinations for thermodynamically stable molecular dispersions.

  9. Application of differential scanning calorimetry to estimate quality and nutritional properties of food products.

    PubMed

    Parniakov, Oleksii; Bals, Olivier; Barba, Francisco J; Mykhailyk, Viacheslav; Lebovka, Nikolai; Vorobiev, Eugene

    2016-05-31

    Over the last years, both food researchers and food industry have shown an increased interest in finding techniques that can estimate the modifications in quality, nutritional and thermophysical properties of food products during processing and/or storage. For instance, differential scanning calorimetry (DSC) has attracted the interest of the scientific community because only a small amount of sample is needed for the analysis. Moreover, it does not require any specific sample preparation and it is a repeatable and reliable method. In addition, DSC methodology needs a short time of experiments compared to other techniques used for the same purpose. At this stage of investigation, there is a need to evaluate the commonly accepted and new emerging DSC applications in order to establish the optimum conditions of emerging processing. This paper reviews the current and new insights of DSC technique for the estimation of quality, nutritional and thermophysical properties of food products during conventional and emerging processing and/or subsequent storage. The estimation of the different properties in several food matrices after processing and/or storage is also discussed.

  10. 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.

  11. 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.

  12. Nucleic acid-lipid membrane interactions studied by DSC.

    PubMed

    Giatrellis, Sarantis; Nounesis, George

    2011-01-01

    The interactions of nucleic acids with lipid membranes are of great importance for biological mechanisms as well as for biotechnological applications in gene delivery and drug carriers. The optimization of liposomal vectors for clinical use is absolutely dependent upon the formation mechanisms, the morphology, and the molecular organization of the lipoplexes, that is, the complexes of lipid membranes with DNA. Differential scanning calorimetry (DSC) has emerged as an efficient and relatively easy-to-operate experimental technique that can straightforwardly provide data related to the thermodynamics and the kinetics of the DNA-lipid complexation and especially to the lipid organization and phase transitions within the membrane. In this review, we summarize DSC studies considering nucleic acid-membrane systems, accentuating DSC capabilities, and data analysis. Published work involving cationic, anionic, and zwitterionic lipids as well as lipid mixtures interacting with RNA and DNA of different sizes and conformations are included. It is shown that despite limitations, issues such as DNA- or RNA-induced phase separation and microdomain lipid segregation, liposomal aggregation and fusion, alterations of the lipid long-range molecular order, as well as membrane-induced structural changes of the nucleic acids can be efficiently treated by systematic high-sensitivity DSC studies.

  13. 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

  14. 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.

  15. 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.

  16. In-pile calorimetry in the joint Sandia/KfK equation-of-state experiments on nuclear fuels

    SciTech Connect

    Breitung, W.M.

    1981-04-01

    Because determination of the fuel energy deposition is of crucial importance in in-pile equation of state (EOS) experiments on nuclear fuels, an in-pile calorimeter was developed for the joint Sandia/KfK EOS series. This report describes calorimeter design, principle, and uncertainty of the energy measurement, as well as the planned test program. The uncertainty in the measured total energy deposition into the EOS test fuel is estimated to + or - 2%.

  17. 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.

  18. 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.

  19. Thermodynamic investigations of nitroxoline sublimation by simultaneous DSC-FTIR method and isothermal TG analysis.

    PubMed

    Gao, Gau-Yi; Lin, Shan-Yang

    2010-01-01

    To investigate the physicochemical characteristics, thermodynamics, possible sublimation process and kinetics of nitroxoline, differential scanning calorimetry (DSC), isothermal thermogravimetry (TG), and Fourier transform infrared (FTIR) microspectroscopy equipped with a micro hot-stage of DSC microscopy assembly (simultaneous DSC-FTIR method) were used. The DSC result indicates that nitroxoline exhibited a sharp endothermic peak at 182 degrees C with enthalpy of 103.1 J/g due to the melting point of nitroxoline. A sublimation behavior of nitroxoline was found from 129 degrees C by gradual weight loss in TG curve. However, the nonisothermal DSC-FTIR method reveals that the temperature at 95 degrees C was the onset temperature of nitroxoline sublimation. A significant difference between DSC-FTIR method and TG analysis suggests that the simultaneous DSC-FTIR method was more sensitive than that of the TG analysis to detect the beginning temperature of nitroxoline sublimation. The sublimation kinetics of nitroxoline determined by isothermal TG analysis evidenced that the zero-order kinetics was followed over the sublimation time. The sublimation enthalpy correction was also carried out by a group additivity approach for the estimation of heat capacity. The enthalpy of nitroxoline sublimation estimated was 86.14 KJ/mol at 298.15 K.

  20. 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.

  1. One-step Real-time Food Quality Analysis by Simultaneous DSC-FTIR Microspectroscopy.

    PubMed

    Lin, Shan-Yang; Lin, Chih-Cheng

    2016-01-01

    This review discusses an analytical technique that combines differential scanning calorimetry and Fourier-transform infrared (DSC-FTIR) microspectroscopy, which simulates the accelerated stability test and detects decomposition products simultaneously in real time. We show that the DSC-FTIR technique is a fast, simple and powerful analytical tool with applications in food sciences. This technique has been applied successfully to the simultaneous investigation of: encapsulated squid oil stability; the dehydration and intramolecular condensation of sweetener (aspartame); the dehydration, rehydration and solidification of trehalose; and online monitoring of the Maillard reaction for glucose (Glc)/asparagine (Asn) in the solid state. This technique delivers rapid and appropriate interpretations with food science applications.

  2. 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.

  3. 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.

  4. 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.

  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. Changes of multi-scale structure during mimicked DSC heating reveal the nature of starch gelatinization

    PubMed Central

    Wang, Shujun; Zhang, Xiu; Wang, Shuo; Copeland, Les

    2016-01-01

    A thorough understanding of starch gelatinization is extremely important for precise control of starch functional properties for food processing and human nutrition. Here we reveal the molecular mechanism of starch gelatinization by differential scanning calorimetry (DSC) in conjunction with a protocol using the rapid viscosity analyzer (RVA) to generate material for analysis under conditions that simulated the DSC heating profiles. The results from DSC, FTIR, Raman, X-ray diffraction and small angle X-ray scattering (SAXS) analyses all showed that residual structural order remained in starch that was heated to the DSC endotherm end temperature in starch:water mixtures of 0.5 to 4:1 (v/w). We conclude from this study that the DSC endotherm of starch at a water:starch ratio of 2 to 4 (v/w) does not represent complete starch gelatinization. The DSC endotherm of starch involves not only the water uptake and swelling of amorphous regions, but also the melting of starch crystallites. PMID:27319782

  8. Changes of multi-scale structure during mimicked DSC heating reveal the nature of starch gelatinization.

    PubMed

    Wang, Shujun; Zhang, Xiu; Wang, Shuo; Copeland, Les

    2016-06-20

    A thorough understanding of starch gelatinization is extremely important for precise control of starch functional properties for food processing and human nutrition. Here we reveal the molecular mechanism of starch gelatinization by differential scanning calorimetry (DSC) in conjunction with a protocol using the rapid viscosity analyzer (RVA) to generate material for analysis under conditions that simulated the DSC heating profiles. The results from DSC, FTIR, Raman, X-ray diffraction and small angle X-ray scattering (SAXS) analyses all showed that residual structural order remained in starch that was heated to the DSC endotherm end temperature in starch:water mixtures of 0.5 to 4:1 (v/w). We conclude from this study that the DSC endotherm of starch at a water:starch ratio of 2 to 4 (v/w) does not represent complete starch gelatinization. The DSC endotherm of starch involves not only the water uptake and swelling of amorphous regions, but also the melting of starch crystallites.

  9. Changes of multi-scale structure during mimicked DSC heating reveal the nature of starch gelatinization

    NASA Astrophysics Data System (ADS)

    Wang, Shujun; Zhang, Xiu; Wang, Shuo; Copeland, Les

    2016-06-01

    A thorough understanding of starch gelatinization is extremely important for precise control of starch functional properties for food processing and human nutrition. Here we reveal the molecular mechanism of starch gelatinization by differential scanning calorimetry (DSC) in conjunction with a protocol using the rapid viscosity analyzer (RVA) to generate material for analysis under conditions that simulated the DSC heating profiles. The results from DSC, FTIR, Raman, X-ray diffraction and small angle X-ray scattering (SAXS) analyses all showed that residual structural order remained in starch that was heated to the DSC endotherm end temperature in starch:water mixtures of 0.5 to 4:1 (v/w). We conclude from this study that the DSC endotherm of starch at a water:starch ratio of 2 to 4 (v/w) does not represent complete starch gelatinization. The DSC endotherm of starch involves not only the water uptake and swelling of amorphous regions, but also the melting of starch crystallites.

  10. In situ stability of substrate-associated cellulases studied by DSC.

    PubMed

    Alasepp, Kadri; Borch, Kim; Cruys-Bagger, Nicolaj; Badino, Silke; Jensen, Kenneth; Sørensen, Trine H; Windahl, Michael S; Westh, Peter

    2014-06-24

    This work shows that differential scanning calorimetry (DSC) can be used to monitor the stability of substrate-adsorbed cellulases during long-term hydrolysis of insoluble cellulose. Thermal transitions of adsorbed enzyme were measured regularly in subsets of a progressing hydrolysis, and the size of the transition peak was used as a gauge of the population of native enzyme. Analogous measurements were made for enzymes in pure buffer. Investigations of two cellobiohydrolases, Cel6A and Cel7A, from Trichoderma reesei, which is an anamorph of the fungus Hypocrea jerorina, showed that these enzymes were essentially stable at 25 °C. Thus, over a 53 h experiment, Cel6A lost less than 15% of the native population and Cel7A showed no detectable loss for either the free or substrate-adsorbed state. At higher temperatures we found significant losses in the native populations, and at the highest tested temperature (49 °C) about 80% Cel6A and 35% of Cel7A was lost after 53 h of hydrolysis. The data consistently showed that Cel7A was more long-term stable than Cel6A and that substrate-associated enzyme was less long-term stable than enzyme in pure buffer stored under otherwise equal conditions. There was no correlation between the intrinsic stability, specified by the transition temperature in the DSC, and the long-term stability derived from the peak area. The results are discussed with respect to the role of enzyme denaturation for the ubiquitous slowdown observed in the enzymatic hydrolysis of cellulose.

  11. Thermal characterization and model free kinetics of aged epoxies and foams using TGA and DSC methods.

    SciTech Connect

    Cordaro, Joseph Gabriel; Kruizenga, Alan Michael; Nissen, April

    2013-10-01

    Two classes of materials, poly(methylene diphenyl diisocyanate) or PMDI foam, and cross-linked epoxy resins, were characterized using thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC), to help understand the effects of aging and %E2%80%9Cbake-out%E2%80%9D. The materials were evaluated for mass loss and the onset of decomposition. In some experiments, volatile materials released during heating were analyzed via mass spectroscopy. In all, over twenty materials were evaluated to compare the mass loss and onset temperature for decomposition. Model free kinetic (MFK) measurements, acquired using variable heating rate TGA experiments, were used to calculate the apparent activation energy of thermal decomposition. From these compiled data the effects of aging, bake-out, and sample history on the thermal stability of materials were compared. No significant differences between aged and unaged materials were detected. Bake-out did slightly affect the onset temperature of decomposition but only at the highest bake-out temperatures. Finally, some recommendations for future handling are made.

  12. PALS and DSC study of nanopores partially filled by hexadecane

    NASA Astrophysics Data System (ADS)

    Šauša, O.; Illeková, E.; Krištiak, J.; Berek, D.; Macová, E.

    2013-06-01

    The controlled porosity glasses (CPG) filled with various amount of hexadecane (HXD) in nanopores were studied both by the positron annihilation lifetime spectroscopy (PALS) and the differential scanning calorimetry (DSC) methods. Two types of CPG matrices were used with average pore sizes 12.6 and 22.2 nm. The PALS measurements showed, that when the process of large pores filling by HXD has started, the long o-Ps lifetime went down to HXD o-Ps lifetime about 3ns [1]. DSC measurements at partially filled nanopores showed always two crystallization peaks [2]. Their positions depended on average pore size of matrix. Third crystallization peak was identified in overfilled samples (only short o-Ps lifetimes were present) and their position in temperature scale was the same as for the bulk HXD peak. The latter peak was independent of the average pore size of matrices. This fact confirms the assumption that processes studied by PALS with the samples that contained smaller amount of HXD in CPG occured inside of nanopores of the matrix.

  13. 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

  14. Low-temperature phase behavior of fatty acid methyl esters by differential scanning calorimetry (DSC)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fatty acid methyl ester (FAME) mixtures have many uses including biodiesel, lubricants, metal-working fluids, surfactants, polymers, coatings, green solvents and phase-change materials. The physical properties of a FAME mixture depends on the fatty acid concentration (FAC) profile. Some products hav...

  15. The effects of minor constituents on biodiesel cold flow properties: Differential scanning calorimetry (DSC) analyses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biodiesel is an alternative diesel fuel made from vegetable oils, animal fats and other lipid feedstocks. Fuel properties and performance of biodiesel during cold weather are influenced by factors related to lipid feedstock as well as small concentrations of monoacylglycerols and other minor constit...

  16. 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.

  17. Probing Perturbation of Bovine Lung Surfactant Extracts by Albumin using DSC and 2H-NMR

    PubMed Central

    Nag, Kaushik; Keough, Kevin M. W.; Morrow, Michael R.

    2006-01-01

    Lung surfactant (LS), a lipid-protein mixture, forms films at the lung air-water interface and prevents alveolar collapse at end expiration. In lung disease and injury, the surface activity of LS is inhibited by leakage of serum proteins such as albumin into the alveolar hypophase. Multilamellar vesicular dispersions of a clinically used replacement, bovine lipid extract surfactant (BLES), to which (2% by weight) chain-perdeuterated dipalmitoylphosphatidycholine (DPPG mixtures-d62) had been added, were studied using deuterium-NMR spectroscopy (2H-NMR) and differential scanning calorimetry (DSC). DSC scans of BLES showed a broad gel to liquid-crystalline phase transition between 10–35°C, with a temperature of maximum heat flow (Tmax) around 27°C. Incorporation of the DPPC-d62 into BLES-reconstituted vesicles did not alter the Tmax or the transition range as observed by DSC or the hydrocarbon stretching modes of the lipids observed using infrared spectroscopy. Transition enthalpy change and 2H-NMR order parameter profiles were not significantly altered by addition of calcium and cholesterol to BLES. 2H-NMR spectra of the DPPC-d62 probes in these samples were characteristic of a single average lipid environment at all temperatures. This suggested either continuous ordering of the bilayer through the transition during cooling or averaging of the DPPC-d62 environment by rapid diffusion between small domains on a short timescale relative to that characteristic of the 2H-NMR experiment. Addition of 10% by weight of soluble bovine serum albumin (1:0.1, BLES/albumin, dry wt/wt) broadened the transition slightly and resulted in the superposition of 2H-NMR spectral features characteristic of coexisting fluid and ordered phases. This suggests the persistence of phase-separated domains throughout the transition regime (5–35°C) of BLES with albumin. The study suggests albumin can cause segregation of protein bound-lipid domains in surfactant at NMR timescales (10−5 s

  18. 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

  19. 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.

  20. Fast-Scan DSC and its role in pharmaceutical physical form characterisation and selection.

    PubMed

    Ford, James L; Mann, Timothy E

    2012-04-01

    Conventional rate Differential Scanning Calorimetry (DSC) has been used for many years as a tool in the analysis of pharmaceutical materials. In recent years an extension of the technique to include fast heating and cooling rates has become more prevalent. Broadly termed Fast-Scan DSC, this review examines the current applications of this technique to the characterisation and selection of pharmaceutical materials. Its increasing use encompasses the characterisation of amorphousness in crystalline materials, the characterisation of polymorphs and polymorphic transitions, the solubility of drugs in polymers, and characterisation of dosage forms. Notwithstanding the advantages of analytical speed in analytical turnover, the review emphasises the advantages of Fast-Scan DSC in its sensitivity which allows the separation of overlapping thermal events, the reduction it provides in degradation during the scanning process and its role in determining solubility in waxy and polymeric based systems. A comparison of the uses of Fast-Scan DSC to modulated DSC techniques and localised thermal analysis is also given.

  1. Water absorption of freeze-dried meat at different water activities: a multianalytical approach using sorption isotherm, differential scanning calorimetry, and nuclear magnetic resonance.

    PubMed

    Venturi, Luca; Rocculi, Pietro; Cavani, Claudio; Placucci, Giuseppe; Dalla Rosa, Marco; Cremonini, Mauro A

    2007-12-26

    Hydration of freeze-dried chicken breast meat was followed in the water activity range of aw=0.12-0.99 by a multianalytical approach comprising of sorption isotherm, differential scanning calorimetry (DSC), and nuclear magnetic resonance (NMR). The amount of frozen water and the shape of the T2-relaxogram were evaluated at each water content by DSC and NMR, respectively. Data revealed an agreement between sorption isotherm and DSC experiments about the onset of bulk water (aw=0.83-0.86), and NMR detected mobile water starting at aw=0.75. The origin of the short-transverse relaxation time part of the meat NMR signal was also reinvestigated through deuteration experiments and proposed to arise from protons belonging to plasticized matrix structures. It is proved both by D2O experiments and by gravimetry that the extra protons not contributing to the water content in the NMR experiments are about 6.4% of the total proton NMR CPMG signal of meat.

  2. Evaluation of integrated Raman-DSC technology in early pharmaceutical development: characterization of polymorphic systems.

    PubMed

    Huang, Jun; Dali, Manisha

    2013-12-01

    Differential Scanning Calorimetry and Raman spectroscopy are both powerful tools used heavily in pharmaceutical development. For many studies such as polymorph characterization these two techniques are complimentary and provide data on different yet important aspects of material properties when combined together. In this work we describe an integrated Raman-DSC technology that simultaneously generates both DSC thermogram and Raman spectra of the pharmaceutical material being studied. The integrated system consists of a DSC with a Raman fiber optic probe inserted right on top of the sample furnace. The technology integrates synchronized Raman acquisition into DSC scan, enabling collection of molecular and structural information coupled with observation of thermal events. We first establish the technology by optimizing the instrumental set-up that offers relatively high-quality results for simultaneous DSC and Raman data collection. We then demonstrate the application of the technology by studying the polymorphs of d-mannitol, a common pharmaceutical excipient and BMS-A, an investigational drug candidate that exhibits multiple coexisting polymorphs. In both cases, the Raman-DSC technology was able to provide valuable information on the process of phase change and polymorph identification. Although similar information may be obtained by using various characterization techniques together, the integrated Raman-DSC indicated special advantages for industrial development such as high efficiency, material sparing and comprehensive data analysis. Moreover the technology provides an alternative to better correlate real-time phase behavior to molecular understanding. The technology thus has the potential to be used for Process Analytical Technology (PAT) purpose.

  3. 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.

  4. A thermoreversible double gel: characterization of a methylcellulose and kappa-carrageenan mixed system in water by SAXS, DSC and rheology.

    PubMed

    Tomsic, Matija; Prossnigg, Florian; Glatter, Otto

    2008-06-01

    Sol-gel and gel-sol thermal transition of methylcellulose/water, kappa-carrageenan/water and methylcellulose/kappa-carrageenan/water mixtures was investigated utilizing small-angle X-ray scattering (SAXS), differential scanning calorimetry (DSC) and oscillatory rheological experiments in temperature regime from 20 to 80 degrees C. Methylcellulose (E461) and kappa-carrageenan (E407) are well-known additives used for gelation in various nutrition and other products. The formulation and characterization of a mixed thermoreversible methylcellulose/kappa-carrageenan/water gel with very interesting double thermal transition gel-sol-gel upon heating was possible. This specific thermal behavior provides a liquid state of the system between the low-temperature and high-temperature gel-state and at the same time allows for the easy temperature tuning of the system's state. As such this system is suggested to be further tested as potential carrier for various functional colloidal systems.

  5. 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.

  6. Characterization of the polycaprolactone melt crystallization: complementary optical microscopy, DSC, and AFM studies.

    PubMed

    Speranza, V; Sorrentino, A; De Santis, F; Pantani, R

    2014-01-01

    The first stages of the crystallization of polycaprolactone (PCL) were studied using several techniques. The crystallization exotherms measured by differential scanning calorimetry (DSC) were analyzed and compared with results obtained by polarized optical microscopy (POM), rheology, and atomic force microscope (AFM). The experimental results suggest a strong influence of the observation scale. In particular, the AFM, even if limited on time scale, appears to be the most sensitive technique to detect the first stages of crystallization. On the contrary, at least in the case analysed in this work, rheology appears to be the least sensitive technique. DSC and POM provide closer results. This suggests that the definition of induction time in the polymer crystallization is a vague concept that, in any case, requires the definition of the technique used for its characterization.

  7. DSC characterization of ion beam modifications in ion conducting PEO salt polymers

    NASA Astrophysics Data System (ADS)

    Maitra, Minakshi; Verma, K. C.; Sinha, Mrinal; Kumar, Rajesh; Middya, T. R.; Tarafdar, S.; Sen, P.; Bandyopadhyay, S. K.; De, Udayan

    2006-03-01

    Ion conducting polymer films have been prepared by complexing non-conducting poly-(ethylene-oxide), PEO, with x fraction of NH4ClO4 salt. Since its electrical conductivity showed a maximum at x somewhere between 0.18 and 0.19, such polymer films having 17 and 19 wt% salt, have been chosen and irradiated by 160 MeV Ne6+ beam. The films have been investigated by differential scanning calorimetry (DSC) and ac impedance spectroscopy before and after the irradiations. Irradiation-induced shift of an endotherm in our DSC indicates a rise in the melting temperature from 54.6 °C to 57.9 °C for the 19% film. Cross-linking by the Ne-irradiation making the polymer structure more rigid can explain this as well as our other observation of a decrease in electrical conductivity.

  8. [Study on the Effects of Ginsenoside Rb1 on DPPC Bilayers by Using Thermo-Raman Spectrum and DSC].

    PubMed

    Hui, Ge; Liu, Wei; Zhang, Jing-zhou; Zhou, Tie-li; Wang, Si-ming; Zhao, Yu; Zhao, Bing

    2015-08-01

    The research on the interactions between Ginsenosides and biomembranes plays a crucial role in thorough understanding the pharmacological activity and biologyical effect of Chinese medicine Panax ginseng. With the bilayer structure, DPPC often serves as an simulation model of the cell membrane to study the role of drug molecules and cell membranes. Ginsenoside Rb1, one of the most important components of Panaxginseng, playing the significant roles of pharmacological effects and biological properties. Raman and differential scanning calorimetry (DSC) are respectively a powerful tool for discussing the molecular interaction, and a kind of general technology by which researching the bilayer monomer structures and its interactions with drug molecules. However, rarely research reports on the interactions between drug molecules and biomembranes by means of both technologies above. In this paper, the influence of ginsenoside monomer Rb1 on DPPC membrane bilayers was investigated by thermo-Raman and DSC. In Raman spectra, the changes of DPPC molecule have been observed before and after interacted with ginsenoside Rb1, the data analysis indicates three aspects: the O-C-C-N+ polar head group skeleton, C-C stretching vibration area, and the C-H bond stretching vibrarion in terminated methyl group of alkyl chains. The results showed that ginsenoside Rb1 molecule with certain concentration has not changed the gauche conformation of the polar head backbone group in DPPC bilayers, the order of the internal molecular chain and the lateral chain-chain packing have been decreased as the temperature increased, the lateral disposed disorder has been increased. The changes of some thermodynamic constants obtained by DSC experiment such as phase transition temperature (Tm), the temperature at which the transition is half completed (ΔT1/2), and the transition enthalpy normalized per mol of DPPC (AH) have been showed further results of the thermo Raman experiments, with increasing the

  9. DSC2 — EDRN Public Portal

    Cancer.gov

    DSC2, a calcium-dependent glycoprotein, is a member of the desmocollin subfamily of the cadherin superfamily. These desmosomal family members, along with the desmogleins, are found primarily in epithelial cells where they constitute the adhesive proteins of the desmosome cell-cell junction and are required for cell adhesion and desmosome formation. The desmosomal family member genes are arranged in two clusters on chromosome 18, occupying less than 650 kb combined. Mutations in this gene are associated with arrhythmogenic right ventricular dysplasia-11, also known as arrhythmogenic right ventricular cardiomyopathy 11, an autosomal dominant disease characterized by partial degeneration of the myocardium of the right ventricle, electrical instability, and sudden death. Alternative splicing results in two transcript variants encoding distinct isoforms; DSC2 is encoded by Isoform 2A.

  10. Expression of the Drosophila Secreted Cuticle Protein 73 (dsc73) Requires Shavenbaby

    PubMed Central

    Andrew, Deborah J.; Baker, Bruce S.

    2010-01-01

    Low stringency genomic library screens with genomic fragments from the sex determination gene doublesex identified the Drosophila secreted cuticle protein 73 (dsc73) gene, which encodes an 852-residue protein with an N-terminal signal sequence. In embryos, dsc73 RNA and protein are expressed to high levels in the epidermal cells that secrete the larval cuticle as well as in other cuticle-secreting tissues such as the trachea and salivary duct. Embryonic expression of dsc73 requires Shavenbaby, a transcription factor regulating cuticle formation. Double-labeling experiments with αCrb and αSAS reveal that, as with chitin and other known cuticle proteins, Dsc73 is secreted apically. Zygotic loss of dsc73 results in larval lethality but loss does not result in overt patterning defects or overt morphological defects in the embryonic tissues in which it is expressed. Thus, dsc73 encodes a novel secreted protein, and it is conserved within the Drosophila group. dsc73 may serve as a useful embryonic marker for cuticular patterning. PMID:18351665

  11. 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.

  12. 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.

  13. 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.

  14. DSC “peak temperature” versus “maximum slope temperature” in determining TSSD temperature

    NASA Astrophysics Data System (ADS)

    Khatamian, D.

    2010-10-01

    One of the concerns of the nuclear industry is the deleterious effect of hydrogen on the structural integrity of the reactor core components due to delayed hydride cracking (DHC). The DHC process occurs when hydrogen concentration exceeds the terminal solid solubility (TSS) in the component. Thus, the accurate knowledge of TSS is necessary to predict the lifetime of the components. Differential scanning calorimetry (DSC) is normally used to measure the hydrogen TSS in zirconium alloys. There is a measurable change in the amount of heat absorbed by the specimen when the hydrides dissolve. The hydride dissolution process does not exhibit a well-defined "sharp" change in the heat-flow signal at the transition temperature. A typical DSC heat-flow curve for hydride dissolution has three definite features; "peak temperature" (PT), "maximum slope temperature" (MST) and "completion temperature". The present investigation aims to identify the part of the heat-flow signal that closely corresponds to the TSS temperature for hydride dissolution ( TTSSD). Coupons were cut from a Zr-2.5Nb specimen, which had been previously hydrided using an electrolytic cell to create a surface hydride layer of ˜20 μm thick on all sides of the specimen. The coupons were then annealed isothermally at various temperatures to establish the TTSSD under equilibrium conditions. Subsequently the hydride layer was removed and the coupons were analyzed for TSSD temperature using DSC. The PT and MST for each DSC run were determined and compared to the annealing temperature of the coupon. The results show that the annealing temperature (the equilibrium TTSSD) is much closer to the DSC PT than any other feature of the heat-flow curve.

  15. In-situ and simultaneous synchrotron-radiation small-angle and 100 scattering experiments on the low-temperature structure in as-quenched Al-Li alloy during heating

    SciTech Connect

    Okuda, Hiroshi; Tanaka, Ichiro; Matoba, Taro; Osamura, Kozo; Amemiya, Yoshiyuki

    1997-12-01

    The kinetics of phase decomposition in Al-Li alloys has been intensively investigated in the last decade. Experimentally, one or two precursory structures were first found by Nozato et al. in the late seventies by using differential scanning calorimetry (DSC). In order to clarify the nature of the dissolution peak appearing in DSC curves, the authors have conducted in-situ synchrotron-radiation (SR) small-angle and 100 scattering (SAS/100) experiments. During heating an as-quenched sample at the heating rate used in the present DSC experiments, the change of the small-angle scattering, representing the spatial distribution of solute concentration, as well as that of 100 profile, representing the spatial distribution of the local degree of order, has been measured. The structure change obtained from in-situ SAS/100 has been compared with the DSC results.

  16. 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.

  17. INSTRUMENTS AND METHODS OF INVESTIGATION: Electron-proton separation in calorimetry experiments directly measuring the composition and energy spectrum of cosmic rays

    NASA Astrophysics Data System (ADS)

    Voronov, Sergei A.; Borisov, Stanislav V.; Karelin, Aleksandr V.

    2009-09-01

    Calorimetric particle detectors that play an important role in high-energy cosmic-ray balloon and satellite experiments not only have the major task of measuring energy but also face the problem of identifying electrons and protons. This problem is usually solved by measuring the longitudinal and traverse shower profiles and the total energy release in the calorimeter, using the fact that electromagnetic and hadronic showers differ in their spatial and energy distributions. In this paper, electron and proton identification methods for different types of calorimeters used in cosmic-ray balloon- and satellite-borne experiments are discussed.

  18. Thermal Hazard Evaluation of Cumene Hydroperoxide-Metal Ion Mixture Using DSC, TAM III, and GC/MS.

    PubMed

    You, Mei-Li

    2016-04-28

    Cumene hydroperoxide (CHP) is widely used in chemical processes, mainly as an initiator for the polymerization of acrylonitrile-butadiene-styrene. It is a typical organic peroxide and an explosive substance. It is susceptible to thermal decomposition and is readily affected by contamination; moreover, it has high thermal sensitivity. The reactor tank, transit storage vessel, and pipeline used for manufacturing and transporting this substance are made of metal. Metal containers used in chemical processes can be damaged through aging, wear, erosion, and corrosion; furthermore, the containers might release metal ions. In a metal pipeline, CHP may cause incompatibility reactions because of catalyzed exothermic reactions. This paper discusses and elucidates the potential thermal hazard of a mixture of CHP and an incompatible material's metal ions. Differential scanning calorimetry (DSC) and thermal activity monitor III (TAM III) were employed to preliminarily explore and narrate the thermal hazard at the constant temperature environment. The substance was diluted and analyzed by using a gas chromatography spectrometer (GC) and gas chromatography/mass spectrometer (GC/MS) to determine the effect of thermal cracking and metal ions of CHP. The thermokinetic parameter values obtained from the experiments are discussed; the results can be used for designing an inherently safer process. As a result, the paper finds that the most hazards are in the reaction of CHP with Fe(2+). When the metal release is exothermic in advance, the system temperature increases, even leading to uncontrollable levels, and the process may slip out of control.

  19. Thermal stability and molecular microstructure of heat-induced cereal grains, revealed with Raman molecular microspectroscopy and differential scanning calorimetry.

    PubMed

    Khan, Md Majibur Rahman; Yu, Peiqiang

    2013-07-03

    The objectives of the present study were to use Raman molecular microspectroscopy and differential scanning calorimetry (DSC) to reveal molecular thermal stability and thermal degradation behavior of heat-induced cereal grains and reveal the molecular chemistry of the protein structures of cereal grain tissues affected by heat processing and to quantify the protein secondary structures using multicomponent peak modeling Gaussian and Lorentzian methods. Hierarchical cluster analysis (CLA) and principal components analysis (PCA) were also conducted to identify molecular differences in the Raman spectra. Three cereal grain seeds, wheat, triticale, and corn, were used as the model for feed protein in the experiment. The specimens were autoclaved (moist heating) and dry-heated (roasted) at 121 °C for 80 min, respectively. Raman spectroscopy results revealed that there are marked differences in the secondary structures of the proteins subjected to various heating treatments of different cereals. The sensitivity of cereals to moist heating was much higher than the sensitivity to dry heating. The multivariate analyses (CLA and PCA) showed that heat treatment was significantly isolated between the different Raman raw spectra. The DSC study revealed that the thermal degradation behavior of cereals was significantly changed after moist- and dry-heat treatments. The position of the major endothermic peak of dry-heated cereals shifted toward a higher temperature, from 131.7 to 134.0 °C, suggesting the high thermal stability of dry-heated cereals. In contrast, the endothermic peak position was slightly decreased to 132.1 °C in the case of moist autoclaved heating. The digestive behavior and nutritive value of rumen-undegradable protein in animals may be related to the changes of the protein secondary molecular structure and thermal stability of the cereal grain materials, which is attributed by Raman microspectroscopy and DSC endotherm profiles.

  20. 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.

  1. 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.

  2. The use of differential scanning calorimetry for the purity verification of pharmaceutical reference standards.

    PubMed

    Mathkar, S; Kumar, S; Bystol, A; Olawoore, K; Min, D; Markovich, R; Rustum, A

    2009-04-05

    Reference standards are routinely used in pharmaceutical industry to determine strength, content, and the quality of drug products, active pharmaceutical ingredients (API), preservatives, antioxidants and excipients. Traditionally, chromatographic techniques such as High Performance Liquid Chromatography (HPLC) and Gas Chromatography (GC) in conjunction with other analytical techniques have been used to determine the purity and strength of a specific lot of a compound for the purpose of qualifying the lot to use as a reference standard. The assigned purity of the reference standard for a wide variety of compounds can be verified using an absolute method such as Differential Scanning Calorimetry (DSC). In this paper, purity of 16 reference standards was determined by DSC and the results were then compared to the purity values that were obtained using HPLC and other analytical techniques. The results indicate that the purity obtained from DSC analysis is comparable to the chromatographic purity for organic compounds that are at least 98% pure. Use of DSC for purity determination is not appropriate if a compound lacks sharp melting point, decomposes in the defined temperature range or exhibits other thermal event(s) which interfere with the melting point of the compound. The use of DSC as an alternative and or complementary method to verify the purity of a compound as part of the pharmaceutical reference standard certification process is discussed.

  3. 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.

  4. {beta}{prime} and {beta} precipitation in an Al-Mg alloy studied by DSC and TEM

    SciTech Connect

    Starink; Zahra, A.M.

    1998-06-12

    Precipitation in Al-16 at. % Mg is investigated by differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). The shape of the {beta}{prime} formation DSC effect is interpreted with a novel theory and the curves obtained on the basis of this new theory fit well to the experimental curves. The s parameter derived from these fits, which is akin to the Avrami parameter n appearing in the Johnson-Mehl-Avrami-Kolmogorov model, is larger than 2.5, indicating that {beta}{prime} precipitation is an autocatalytic process. TEM showed the abundant presence of defects (mostly dislocation loops) but no evidence of nucleation of {beta}{prime} precipitates on these defects. The enthalpies of formation of the {beta} and {beta}{prime} phases are derived as 15.7 and 11.5 kJ per mol Mg, respectively.

  5. The slow relaxation dynamics in active pharmaceutical ingredients studied by DSC and TSDC: Voriconazole, miconazole and itraconazole.

    PubMed

    Ramos, Joaquim J Moura; Diogo, Hermínio P

    2016-03-30

    The slow molecular mobility of three active pharmaceutical drugs (voriconazole, miconazole and itraconazole) has been studied by differential scanning calorimetry (DSC) and thermally stimulated depolarization currents (TSDC). This study yielded the main kinetic features of the secondary relaxations and of the main (glass transition) relaxation, in particular their distribution of relaxation times. The dynamic fragility of the three glass formers was determined from DSC data (using two different procedures) and from TSDC data. According to our results voriconazole behaves as a relatively strong liquid, while miconazole is moderately fragile and itraconazole is a very fragile liquid. There are no studies in this area published in the literature relating to voriconazole. Also not available in the literature is a slow mobility study by dielectric relaxation spectroscopy in the amorphous miconazole. Apart from that, the results obtained are in reasonable agreement with published works using different experimental techniques.

  6. Simultaneous screening and detection of pharmaceutical co-crystals by the one-step DSC-FTIR microspectroscopic technique.

    PubMed

    Lin, Shan-Yang

    2016-12-12

    Various methods and analytical techniques for the preparation and identification of pharmaceutical co-crystals have been applied, but these operations require considerable time for the screening and preparation of co-crystals. In this review, a powerful method that combines Fourier-transform infrared (FTIR) microspectroscopy with thermal analysis is introduced. This unique one-step real-time differential scanning calorimetry (DSC)-FTIR microspectroscopic approach has been successfully applied to simultaneously and directly screen and detect pharmaceutical co-crystal formation in systems such as indomethacin-saccharin, indomethacin-nicotinamide, carbamazepine-glutaric-acid, metaxalone-succinic-acid and piroxicam-saccharin. This powerful one-step DSC-FTIR combined technique provides an easy and direct method for one-step screening and qualitative detection of co-crystal formation in real time.

  7. DSC and curing kinetics study of epoxy grouting diluted with furfural -acetone slurry

    NASA Astrophysics Data System (ADS)

    Yin, H.; Sun, D. W.; Li, B.; Liu, Y. T.; Ran, Q. P.; Liu, J. P.

    2016-07-01

    The use of furfural-acetone slurry as active diluents of Bisphenol-A epoxy resin (DGEBA) groutings has been studied by dynamic and non-isothermal DSC for the first time. Curing kinetics study was investigated by non-isothermal differential scanning calorimetries at different heating rates. Activation enery (Ea) was calculated based on Kissinger and Ozawa Methods, and the results showed that Ea increased from 58.87 to 71.13KJ/mol after the diluents were added. The furfural-acetone epoxy matrix could cure completely at the theoretical curing temperature of 365.8K and the curing time of 139mins, which were determined by the kinetic model parameters.

  8. Molecular characterization of DSC1 orthologs in invertebrate species.

    PubMed

    Cui, Ying-Jun; Yu, Lin-Lin; Xu, Hai-Jun; Dong, Ke; Zhang, Chuan-Xi

    2012-05-01

    DSC1 and BSC1 are two founding members of a novel family of invertebrate voltage-gated cation channels with close structural and evolutionary relationships to voltage-gated sodium and calcium channels. In this study, we searched the published genome sequences for DSC1 orthologs. DSC1 orthologs were found in all 48 insect species, and in other invertebrate species belonging to phyla Mollusca, Cnidaria, Hemichordata and Echinodermata. However, DSC1 orthologs were not found in four arachnid species, Ixodes scapularis, Rhipicephalus microplus, Tetranychus urticae and Varroa destructor, two species in Annelida or any vertebrate species. We then cloned and sequenced NlSC1 and BmSC1 full-length cDNAs from the brown planthopper (Nilaparvata lugens) and the silkworm (Bombyx mori), respectively. NlSC1 and BmSC1 share about 50% identity with DSC1, and the expression of NlSC1 and BmSC1 transcripts was most abundant in the head and antenna in adults. All DSC1 orthologs contain a unique and conserved DEEA motif, instead of the EEEE or EEDD motif in classical calcium channels or the DEKA motif in sodium channels. Phylogenetic analyses revealed that DSC1 and its orthologs form a separate group distinct from the classical voltage-gated sodium and calcium channels and constitute a unique family of cation channels. The DSC1/BSC1-family channels could be potential targets of new and safe insecticides for pest control.

  9. 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.

  10. Multivariate statistical analysis treatment of DSC thermal properties for animal fat adulteration.

    PubMed

    Dahimi, Omar; Rahim, Alina Abdul; Abdulkarim, S M; Hassan, Mohd Sukri; Hashari, Shazamawati B T Zam; Mashitoh, A Siti; Saadi, Sami

    2014-09-01

    The adulteration of edible fats is a kind of fraud that impairs the physical and chemical features of the original lipid materials. It has been detected in various food, pharmaceutical and cosmeceutical products. Differential scanning calorimetry (DSC) is the robust thermo-analytical machine that permits to fingerprint the primary crystallisation of triacylglycerols (TAGs) molecules and their transition behaviours. The aims of this study was to assess the cross-contamination caused by lard concentration of 0.5-5% in the mixture systems containing beef tallow (BT) and chicken fat (CF) separately. TAGs species of pure and adulterated lipids in relation to their crystallisation and melting parameters were studied using principal components analysis (PCA). The results showed that by using the heating profiles the discrimination of LD from BT and CF was very clear even at low dose of less than 1%. Same observation was depicted from the crystallisation profiles of BT adulterated by LD doses ranging from 0.1% to 1% and from 2% to 5%, respectively. Furthermore, CF adulterated with LD did not exhibit clear changes on its crystallisation profiles. Consequently, DSC coupled with PCA is one of the techniques that might use to monitor and differentiate the minimum adulteration levels caused by LD in different animal fats.

  11. Interactions of tamoxifen with distearoyl phosphatidylcholine multilamellar vesicles: FTIR and DSC studies.

    PubMed

    Bilge, Duygu; Sahin, Ipek; Kazanci, Nadide; Severcan, Feride

    2014-09-15

    Interactions of a non-steroidal antiestrogen drug, tamoxifen (TAM), with distearoyl-sn-glycero-3-phosphatidylcholine (DSPC) multilamellar liposomes (MLVs) were investigated as a function of drug concentration (1-15 mol%) by using two noninvasive techniques, namely Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). FTIR spectroscopy results show that increasing TAM concentrations (except 1 mol%) increased the wavenumbers of the CH2 stretching modes, implying an disordering effect for DSPC MLVs both in the gel and liquid crystalline phases. The bandwidth values of the CH2 stretchings except for 1 mol% increased when TAM concentrations increased for DSPC liposomes, indicating an increase in the dynamics of liposomes. The CO stretching and PO2- antisymmetric double bond stretching bands were analyzed to study interactions of TAM with head groups of lipids. As the concentrations of TAM increased, dehydration occurred around these functional groups in the polar part of the lipids. The DSC studies on thermal properties of DSPC lipids indicate that TAM eliminated the pre transition, shifted the main phase transition to lower temperatures and broadened the phase transition curve of the liposomes.

  12. Application of chemometric methods to differential scanning calorimeter (DSC) to estimate nimodipine polymorphs from cosolvent system.

    PubMed

    Siddiqui, Akhtar; Rahman, Ziyaur; Khan, Mansoor A

    2015-06-01

    The focus of this study was to evaluate the applicability of chemometrics to differential scanning calorimetry data (DSC) to evaluate nimodipine polymorphs. Multivariate calibration models were built using DSC data from known mixtures of the nimodipine modification. The linear baseline correction treatment of data was used to reduce dispersion in thermograms. Principal component analysis of the treated and untreated data explained 96% and 89% of the data variability, respectively. Score and loading plots correlated variability between samples with change in proportion of nimodipine modifications. The R(2) for principal component regression (PCR) and partial lease square regression (PLS) were found to be 0.91 and 0.92. The root mean square of standard error of the treated samples for calibration and validation in PCR and PLS was found to be lower than the untreated sample. These models were applied to samples recrystallized from a cosolvent system, which indicated different proportion of modifications in the mixtures than those obtained by placing samples under different storage conditions. The model was able to predict the nimodipine modifications with known margin of error. Therefore, these models can be used as a quality control tool to expediently determine the nimodipine modification in an unknown mixture.

  13. Synergistic gel formation of xyloglucan/gellan mixtures as sudied by rheology, DSC, and circular dichroism.

    PubMed

    Nitta, Yoko; Kim, Bo S; Nishinari, Katsuyoshi; Shirakawa, Mayumi; Yamatoya, Kazuhiko; Oomoto, Toshio; Asai, Iwao

    2003-01-01

    The gelation behavior of mixtures of tamarind seed xyloglucan (TSX) and sodium form gellan (Na-G) was investigated. The storage and loss shear moduli, G' and G'', of the mixtures showed that a thermoreversible gel was obtained although each polysaccharide alone did not form a gel at experimental conditions. The viscoelastic behavior of the mixtures showed a gel formation of TSX and Na-G induced by synergistic interaction. This synergistic interaction was also revealed by differential scanning calorimetry (DSC) and circular dichroism. Although TSX alone did not show any peak in DSC curves, mixtures with only a small amount of Na-G, which by itself did not show any peak, showed a single peak. With increasing Na-G content, another peak began to appear at the same temperature at which a peak of Na-G alone appeared. Thermally induced changes in circular dichroism of the mixtures were different from those expected from the individual behavior of TSX and Na-G.

  14. Interactions of tamoxifen with distearoyl phosphatidylcholine multilamellar vesicles: FTIR and DSC studies

    NASA Astrophysics Data System (ADS)

    Bilge, Duygu; Sahin, Ipek; Kazanci, Nadide; Severcan, Feride

    2014-09-01

    Interactions of a non-steroidal antiestrogen drug, tamoxifen (TAM), with distearoyl-sn-glycero-3-phosphatidylcholine (DSPC) multilamellar liposomes (MLVs) were investigated as a function of drug concentration (1-15 mol%) by using two noninvasive techniques, namely Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). FTIR spectroscopy results show that increasing TAM concentrations (except 1 mol%) increased the wavenumbers of the CH2 stretching modes, implying an disordering effect for DSPC MLVs both in the gel and liquid crystalline phases. The bandwidth values of the CH2 stretchings except for 1 mol% increased when TAM concentrations increased for DSPC liposomes, indicating an increase in the dynamics of liposomes. The Cdbnd O stretching and PO2- antisymmetric double bond stretching bands were analyzed to study interactions of TAM with head groups of lipids. As the concentrations of TAM increased, dehydration occurred around these functional groups in the polar part of the lipids. The DSC studies on thermal properties of DSPC lipids indicate that TAM eliminated the pre transition, shifted the main phase transition to lower temperatures and broadened the phase transition curve of the liposomes.

  15. Thermal stability of porcine pepsin influenced by Al(III) ion: DSC study

    NASA Astrophysics Data System (ADS)

    Pavelkić, V. M.; Beljanski, M. V.; Antić, K. M.; Babić, M. M.; Brdarić, T. P.; Gopčević, K. R.

    2011-12-01

    Differential scanning calorimetry (DCS) has been used to determine thermodynamic profile of pepsin and the in vitro effect of Al(III) ions. Thermograms of pepsin unfolding in the presence and absence of aluminum were used to determine the binding constant, K L, in the pepsin-aluminium model system. The thermodynamic parameters were derived from DSC profiles at different ligand concentrations (1, 5 and 10 mM). The temperatures of thermal transitions ( T m), calorimetric (Δ H cal) and van't Hoff enthalpy (Δ H VH), Gibbs free energy, Δ(Δ G), of Al(III) binding to pepsin, as well as an average number of ligands bound to the native protein, were obtained from DSC profiles too. Temperature-dependent changes in the protein structure were also monitored by native PAGE electrophoresis. Increasing the temperature causes the decrease in electrophoretic mobility. Increase in concentration of Al(III) decelerate the migration of pepsin samples on concentration dependent manner. Analysis showed that ligand binding increases thermal stability of protein.

  16. Structure of rat skin after application of electret characterized by DSC

    NASA Astrophysics Data System (ADS)

    Cui, L. L.; Liang, Y. Y.; Dong, F. J.; Ma, L.; Tu, Y.; Liu, H. Y.; Jiang, J.

    2011-06-01

    Polypropylene (PP) electrets with surface potential of -500V, -1000V and -2000V were prepared by constant voltage corona charging. The electrets were applied to excised rat skin for 2 hours respectively and then the skin samples were analyzed with the differential scanning calorimetry (DSC) technique to study the alteration of lipid organization of the skin. There were three peaks at 63°C, 82.7°C and 115.1°C in the DSC spectra for rat skin untreated, which have been assigned essentially to lipid, lipid-protein and protein alterations. For -500V electret treated-skin sample, only a single peak appeared at 79.1°C. With the increase of electret surface potential from -500V to -2000V, the transition temperature and peak areas at moderate decreased first and then increased. The negative electret could result in the transition of stratum corneum (SC) lipid from gel to liquid crystal and protein transition from α helix structure to β folding structure. The regulation action of electret to skin mircostructure presented an effect of "potential window".

  17. Drug-polymer interaction between glucosamine sulfate and alginate nanoparticles: FTIR, DSC and dielectric spectroscopy studies

    NASA Astrophysics Data System (ADS)

    El-Houssiny, A. S.; Ward, A. A.; Mostafa, D. M.; Abd-El-Messieh, S. L.; Abdel-Nour, K. N.; Darwish, M. M.; Khalil, W. A.

    2016-06-01

    This work involves the preparation and characterization of alginate nanoparticles (Alg NPs) as a new transdermal carrier for site particular transport of glucosamine sulfate (GS). The GS-Alg NPs were examined through transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and dielectric spectroscopy. GS-Alg NPs was efficiently prepared via ionic gelation method which generates favorable conditions for the entrapment of hydrophilic drugs. The TEM studies revealed that GS-Alg NPs are discrete and have spherical shapes. FTIR studies showed a spectral change of the characteristic absorptions bands of Alg NPs after encapsulation with GS because of the amine groups of GS and the carboxylic acid groups of Alg. The DSC data showed changes in the thermal behavior of GS-Alg NPs after the addition of GS indicating signs of main chemical interaction among the drug (GS) and the polymer (Alg). The absence of the drug melting endothermic peak within the DSC thermogram of GS-Alg NPs indicating that GS is molecularly dispersed in the NPs and not crystallize. From the dielectric study, it was found modifications within the dielectric loss (ɛ″) and conductivity (σ) values after the addition of GS. The ɛ″ and σ values of Alg NPs decreased after the addition of GS which indicated the successful encapsulation of GS within Alg NPs. Furthermore, the dielectric study indicated an increase of the activation energy and the relaxation time for the first process in the GS-Alg NPs as compared to Alg NPs. Consequently, the existing observations indicated an initiation of electrostatic interaction among the amine group of GS and carboxyl group of Alg indicating the successful encapsulation of GS inside Alg NPs which could provide favorable circumstance for the encapsulation of GS for topical management.

  18. The potential of high speed DSC (hyper-DSC) for the detection and quantification of small amounts of amorphous content in predominantly crystalline samples.

    PubMed

    Saunders, Mark; Podluii, Kalyan; Shergill, Sukhraj; Buckton, Graham; Royall, Paul

    2004-04-15

    The purpose of this study was to explore whether it is possible to use hyper differential scanning calorimetry (HDSC) to detect and quantify low levels of amorphous content in samples that are mostly crystalline. HDSC uses scan rates that are much faster than conventional DSC, and consequently results in greater sensitivity. It was found that with every increase in scan rate it became easier to detect the glass transition (Tg) response. Scanning at 500 degrees C/min was possible and this gave such great sensitivity that very low sample mass (ca. 1 mg) could be used without any loss in detection of Tg. Mixtures of crystalline and amorphous (spray dried) lactose were prepared and scanned at 500 degrees C/min. It was observed that the Tg response was easily detected even for samples that contained 1.5% amorphous content when using very low samples mass. The view held at present is that DSC is not well suited to studies of amorphous content if the sample contains 10% or less of the amorphous material. The data generated here show that much better detection sensitivity is possible when using the rapid scan rates. As well as being able to detect the presence of very low amorphous contents it was also possible to obtain a quantification, as a linear response was obtained for the step height change in heat flow as a function of amorphous content. It was concluded that HDSC provides a method of obtaining a very fast assessment of the presence of amorphous form, the possibility to quantify this and the need to use a very low sample mass. The combination of speed, low sample mass and sensitivity makes this a very valuable technique for studies on partially amorphous samples.

  19. 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.

  20. 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.

  1. 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.

  2. DSC deconvolution of the structural complexity of c-MYC P1 promoter G-quadruplexes.

    PubMed

    Dettler, Jamie M; Buscaglia, Robert; Le, Vu H; Lewis, Edwin A

    2011-03-16

    We completed a biophysical characterization of the c-MYC proto-oncogene P1 promoter quadruplex and its interaction with a cationic porphyrin, 5,10,15,20-tetra(N-methyl-4-pyridyl)porphyrin (TMPyP4), using differential scanning calorimetry, isothermal titration calorimetry, and circular dichroism spectroscopy. We examined three different 24-mer oligonucleotides, including the wild-type (WT) sequence found in the c-MYC P(1) promoter and two mutant G→T sequences that are known to fold into single 1:2:1 and 1:6:1 loop isomer quadruplexes. Biophysical experiments were performed on all three oligonucleotide sequences at two different ionic strengths (30 mM [K(+)] and 130 mM [K(+)]). Differential scanning calorimetry experiments demonstrated that the WT quadruplex consists of a mixture of at least two different folded conformers at both ionic strengths, whereas both mutant sequences exhibit a single two-state melting transition at both ionic strengths. Isothermal titration calorimetry experiments demonstrated that both mutant sequences bind 4 mols of TMPyP4 to 1 mol of DNA, in similarity to the WT sequence. The circular dichroism spectroscopy signatures for all three oligonucleotides at both ionic strengths are consistent with an intramolecular parallel stranded G-quadruplex structure, and no change in quadruplex structure is observed upon addition of saturating amounts of TMPyP4 (i.e., 4:1 TMPyP4/DNA).

  3. 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.

  4. Differential Scanning Calorimetry and Evolved Gas Analysis at Mars Ambient Conditions Using the Thermal Evolved Gas Analyser (TEGA)

    NASA Technical Reports Server (NTRS)

    Musselwhite, D. S.; Boynton, W. V.; Ming, D. W.; Quadlander, G.; Kerry, K. E.; Bode, R. C.; Bailey, S. H.; Ward, M. G.; Pathare, A. V.; Lorenz, R. D.

    2000-01-01

    Differential Scanning Calorimetry (DSC) combined with evolved gas analysis (EGA) is a well developed technique for the analysis of a wide variety of sample types with broad application in material and soil sciences. However, the use of the technique for samples under conditions of pressure and temperature as found on other planets is one of current development and cutting edge research. The Thermal Evolved Gas Analyzer (TEGA), which was designed, built and tested at the University of Arizona's Lunar and Planetary Lab (LPL), utilizes DSC/EGA. TEGA, which was sent to Mars on the ill-fated Mars Polar Lander, was to be the first application of DSC/EGA on the surface of Mars as well as the first direct measurement of the volatile-bearing mineralogy in martian soil. Additional information is available in the original extended abstract.

  5. Differential Scanning Calorimetry and Evolved Gas Analysis at Mars Ambient Conditions Using the Thermal Evolved Gas Analyzer (TEGA)

    NASA Technical Reports Server (NTRS)

    Musselwhite, D. S.; Boynton, W. V.; Ming, Douglas W.; Quadlander, G.; Kerry, K. E.; Bode, R. C.; Bailey, S. H.; Ward, M. G.; Pathare, A. V.; Lorenz, R. D.

    2000-01-01

    Differential Scanning Calorimetry (DSC) combined with evolved gas analysis (EGA) is a well developed technique for the analysis of a wide variety of sample types with broad application in material and soil sciences. However, the use of the technique for samples under conditions of pressure and temperature as found on other planets is one of current C development and cutting edge research. The Thermal Evolved Gas Analyzer (MGA), which was designed, built and tested at the University of Arizona's Lunar and Planetary Lab (LPL), utilizes DSC/EGA. TEGA, which was sent to Mars on the ill-fated Mars Polar Lander, was to be the first application of DSC/EGA on the surface of Mars as well as the first direct measurement of the volatile-bearing mineralogy in martian soil.

  6. 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.

  7. Process induced transformations during tablet manufacturing: phase transition analysis of caffeine using DSC and low frequency micro-Raman spectroscopy.

    PubMed

    Hubert, Sébastien; Briancon, Stéphanie; Hedoux, Alain; Guinet, Yannick; Paccou, Laurent; Fessi, Hatem; Puel, François

    2011-11-25

    The phase transition of a model API, caffeine Form I, was studied during tableting process monitored with an instrumented press. The formulation used had a plastic flow behavior according to the Heckel model in the compression pressure range of 70-170 MPa. The quantitative methods of analysis used were Differential Scanning Calorimetry (DSC) and low frequency Micro Raman Spectroscopy (MRS) which was used for the first time for the mapping of polymorphs in tablets. They brought complementary contributions since MRS is a microscopic spectral analysis with a spatial resolution of 5 μm(3) and DSC takes into account a macroscopic fraction (10mg) of the tablet. Phase transitions were present at the surfaces, borders and center of the tablets. Whatever the pressure applied during the compression process, the transition degree of caffeine Form I toward Form II was almost constant. MRS provided higher transition degrees (50-60%) than DSC (20-35%). MRS revealed that caffeine Form I particles were partially transformed in all parts of the tablets at a microscopic scale. Moreover, tablet surfaces showed local higher transition degree compared to the other parts.

  8. Advances in simultaneous DSC-FTIR microspectroscopy for rapid solid-state chemical stability studies: some dipeptide drugs as examples.

    PubMed

    Lin, Shan-Yang; Wang, Shun-Li

    2012-04-01

    The solid-state chemistry of drugs has seen growing importance in the pharmaceutical industry for the development of useful API (active pharmaceutical ingredients) of drugs and stable dosage forms. The stability of drugs in various solid dosage forms is an important issue because solid dosage forms are the most common pharmaceutical formulation in clinical use. In solid-state stability studies of drugs, an ideal accelerated method must not only be selected by different complicated methods, but must also detect the formation of degraded product. In this review article, an analytical technique combining differential scanning calorimetry and Fourier-transform infrared (DSC-FTIR) microspectroscopy simulates the accelerated stability test, and simultaneously detects the decomposed products in real time. The pharmaceutical dipeptides aspartame hemihydrate, lisinopril dihydrate, and enalapril maleate either with or without Eudragit E were used as testing examples. This one-step simultaneous DSC-FTIR technique for real-time detection of diketopiperazine (DKP) directly evidenced the dehydration process and DKP formation as an impurity common in pharmaceutical dipeptides. DKP formation in various dipeptides determined by different analytical methods had been collected and compiled. Although many analytical methods have been applied, the combined DSC-FTIR technique is an easy and fast analytical method which not only can simulate the accelerated drug stability testing but also at the same time enable to explore phase transformation as well as degradation due to thermal-related reactions. This technique offers quick and proper interpretations.

  9. '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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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)

  15. 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.

  16. 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.

  17. 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.

  18. Combination of TREF, high-temperature HPLC, FTIR and HPer DSC for the comprehensive analysis of complex polypropylene copolymers.

    PubMed

    Cheruthazhekatt, Sadiqali; Pijpers, Thijs F J; Mathot, Vincent B F; Pasch, Harald

    2013-11-01

    A novel, powerful analytical technique, preparative temperature rising elution fractionation (prep TREF)/high-temperature (HT)-HPLC/Fourier transform infrared spectroscopy (FTIR)/high-performance differential scanning calorimetry (HPer DSC)), has been introduced to study the correlation between the polymer chain microstructure and the thermal behaviour of various components in a complex impact polypropylene copolymer (IPC). For the comprehensive analysis of this complex material, in a first step, prep TREF is used to produce less complex but still heterogeneous fractions. These chemically heterogeneous fractions are completely separated by using a highly selective chromatographic separation method--high-temperature solvent gradient HPLC. The detailed structural and thermal analysis of the HPLC fractions was conducted by offline coupling of HT-HPLC with FTIR spectroscopy and a novel DSC method--HPer DSC. Three chemically different components were identified in the mid-elution temperature TREF fractions. For the first component, identified as isotactic polypropylene homopolymer by FTIR, the macromolecular chain length is found to be an important factor affecting the melting and crystallisation behaviour. The second component relates to ethylene-propylene copolymer molecules with varying ethylene monomer distributions and propylene tacticity distributions. For the polyethylene component (last eluting component in all semi-crystalline TREF fractions), it was found that branching produced defects in the long crystallisable ethylene sequences that affected the thermal properties. The different species exhibit distinctively different melting and crystallisation behaviour, as documented by HPer DSC. Using this novel approach of hyphenated techniques, the chain structure and melting and crystallisation behaviour of different components in a complex copolymer were investigated systematically.

  19. 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.

  20. Calibration of Chemical Kinetic Models Using Simulations of Small-Scale Cookoff Experiments

    SciTech Connect

    Wemhoff, A P; Becker, R C; Burnham, A K

    2008-02-26

    Establishing safe handling limits for explosives in elevated temperature environments is a difficult problem that often requires extensive simulation. The largest influence on predicting thermal cookoff safety lies in the chemical kinetic model used in these simulations, and these kinetic model reaction sequences often contain multiple steps. Several small-scale cookoff experiments, notably Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), One-Dimensional Time-to-Explosion (ODTX), and the Scaled Thermal Explosion (STEX) have been performed on various explosives to aid in cookoff behavior determination. Past work has used a single test from this group to create a cookoff model, which does not guarantee agreement with the other experiments. In this study, we update the kinetic parameters of an existing model for the common explosive 2,4,6-Trinitrotoluene (TNT) using DSC and ODTX experimental data at the same time by minimizing a global Figure of Merit based on hydrodynamic simulated data. We then show that the new kinetic model maintains STEX agreement, reduces DSC agreement, and improves ODTX and TGA agreement when compared to the original model. In addition, we describe a means to use implicit hydrodynamic simulations of DSC experiments to develop a reaction model for TNT melting.

  1. 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.

  2. 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.

  3. Liquid Argon Calorimetry for ATLAS

    NASA Astrophysics Data System (ADS)

    Robinson, Alan

    2008-05-01

    This summer, the largest collaborative physics project since the Manhattan project will go online. One of four experiments for the Large Hadron Collider at CERN in Geneva, ATLAS, employs over 2000 people. Canadians have helped design, construct, and calibrate the liquid argon calorimeters for ATLAS to capture the products of the high energy collisions produced by the LHC. From an undergraduate's perspective, explore how these calorimeters are made to handle their harsh requirement. From nearly a billion proton-proton collisions a second, physicists hope to discover the Higgs boson and other new fundamental particles.

  4. Raman, DSC, ESR and optical properties of lithium cadmium zinc tellurite glasses

    NASA Astrophysics Data System (ADS)

    Sreenivasulu, V.; Upender, G.; Swapna; Priya, V. Vamsi; Mouli, V. Chandra; Prasad, M.

    2014-12-01

    The glasses with composition 64TeO2-15ZnO-(20-x)CdO-xLi2O-1V2O5 (0≤x≤20 mol%) were prepared by conventional melt quenching technique. X-ray diffraction was used to confirm the amorphous nature. The optical absorption studies revealed that the cut-off wavelength decreases while optical energy gap (Eopt) and Urbach energy (ΔE) values increase with an increase of Li2O. Refractive index (n) evaluated from Eopt was found to decrease with increase of Li2O content. The physical parameters such as density (ρ), molar volume (Vm) and oxygen packing density (OPD) have been analyzed and discussed. The electron paramagnetic resonance (EPR) spectra of VO2+ glasses have been recorded on X-band (v=9.14 GHz) at room temperature. The spin Hamiltonian parameters of VO2+ ions have been calculated. It has been found that V4+ ions in these glasses exist as VO2+ in octahedral coordination with a tetragonal distortion. Raman spectroscopic studies showed that the glass network consists of TeO4, TeO3+1/TeO3 and ZnO4 units as basic structural units. The glass transition temperature (Tg), onset crystallization (To) and thermal stability (ΔT) were determined from Differential Scanning Calorimetry (DSC).

  5. DSC studies of retrogradation and amylose lipid complex transition taking place in gamma irradiated wheat starch

    NASA Astrophysics Data System (ADS)

    Cieśla, K.; Eliasson, A. C.

    2007-12-01

    The effect of gamma irradiation ( 60Co) with doses of 5-30 kGy on the amylose-lipid complex transition and retrogradation occurring in gels containing ca. 50% and ca. 20% wheat starch was studied by differential scanning calorimetry (DSC) during heating-cooling-heating cycles (up to three cycles). Transition of the amylose-lipid complex occurs in all the irradiated samples at a lower temperature as compared to the non-irradiated starch. That effect was larger when the radiation dose was higher. A further thermal treatment causes a decrease of the transition temperature in the irradiated samples, with no effect or increase of that temperature observed for the non-irradiated ones. Irradiation hinders retrogradation taking place in 50% gels but facilitates the process occurring in 20% gels. The differences between the irradiated and the non-irradiated samples are more evident in the every next heating or cooling cycle as well as after storage and in the case of ca. 50% suspensions as compared to ca. 20% suspensions. The results point out to the deterioration of the structure of the complexes formed in the irradiated starch as compared to the non-irradiated one.

  6. Kinetics of Thermal Decomposition of Ammonium Perchlorate by TG/DSC-MS-FTIR

    NASA Astrophysics Data System (ADS)

    Zhu, Yan-Li; Huang, Hao; Ren, Hui; Jiao, Qing-Jie

    2014-01-01

    The method of thermogravimetry/differential scanning calorimetry-mass spectrometry-Fourier transform infrared (TG/DSC-MS-FTIR) simultaneous analysis has been used to study thermal decomposition of ammonium perchlorate (AP). The processing of nonisothermal data at various heating rates was performed using NETZSCH Thermokinetics. The MS-FTIR spectra showed that N2O and NO2 were the main gaseous products of the thermal decomposition of AP, and there was a competition between the formation reaction of N2O and that of NO2 during the process with an iso-concentration point of N2O and NO2. The dependence of the activation energy calculated by Friedman's iso-conversional method on the degree of conversion indicated that the AP decomposition process can be divided into three stages, which are autocatalytic, low-temperature diffusion and high-temperature, stable-phase reaction. The corresponding kinetic parameters were determined by multivariate nonlinear regression and the mechanism of the AP decomposition process was proposed.

  7. PALS and DSC measurements in 8 MeV electron irradiated natural rubber filled with different fillers

    NASA Astrophysics Data System (ADS)

    Mandal, Arunava; Pan, Sandip; Roychowdhury, Anirban; Sengupta, Asmita

    2015-10-01

    The effect of high energy electron irradiation on the microstructure and thermal properties of natural rubber (NR) filled with different fillers at different concentrations are studied. The samples are irradiated with 8 MeV electron beam to a total dose of 100 KGy. The change in free volume size and specific heat due to addition of fillers and irradiation are studied using positron annihilation lifetime spectroscopy (PALS) and differential scanning calorimetry (DSC) respectively. The Positron lifetime spectra are de-convoluted into two components. The longer lived component (τo-Ps) signifies the pick-off annihilation of ortho-positronium (o-Ps) at free volume site which may be related to the radius of the free volume holes. It is observed that the specific heat (Cp) and free volume size are all affected by both irradiation and addition of fillers.

  8. Differential Scanning Calorimetry and Evolved Gas Analysis at Mars Ambient Conditions Using the Thermal Evolved Gas Analyser (TEGA)

    NASA Technical Reports Server (NTRS)

    Musselwhite, D. S.; Boynton, W. V.; Ming, D. W.; Quadlander, G. A.; Kerry, K. E.; Bode, R. C.; Bailey, S. H.; Ward, M. G.; Pathare, A. V.; Lorenz, R. D.

    2000-01-01

    We are conducting DSC/EGA experiments at Mars ambient temperature and pressure using the TEGA engineering model. These tests illustrate the outstanding capabilities of a TEGA-like instrument on the surface of Mars.

  9. 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.

  10. 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…

  11. 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.

  12. 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)

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 7 CFR 1710.114 - TIER, DSC, OTIER and ODSC requirements.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 11 2012-01-01 2012-01-01 false TIER, DSC, OTIER and ODSC requirements. 1710.114... AND GUARANTEES Loan Purposes and Basic Policies § 1710.114 TIER, DSC, OTIER and ODSC requirements. (a... of distribution borrowers whether applied on an annual or average basis, are a TIER of 1.25, DSC of...

  4. 7 CFR 1710.114 - TIER, DSC, OTIER and ODSC requirements.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 11 2011-01-01 2011-01-01 false TIER, DSC, OTIER and ODSC requirements. 1710.114... AND GUARANTEES Loan Purposes and Basic Policies § 1710.114 TIER, DSC, OTIER and ODSC requirements. (a... of distribution borrowers whether applied on an annual or average basis, are a TIER of 1.25, DSC of...

  5. 7 CFR 1710.114 - TIER, DSC, OTIER and ODSC requirements.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 11 2014-01-01 2014-01-01 false TIER, DSC, OTIER and ODSC requirements. 1710.114... AND GUARANTEES Loan Purposes and Basic Policies § 1710.114 TIER, DSC, OTIER and ODSC requirements. (a... of distribution borrowers whether applied on an annual or average basis, are a TIER of 1.25, DSC of...

  6. 7 CFR 1710.114 - TIER, DSC, OTIER and ODSC requirements.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 11 2013-01-01 2013-01-01 false TIER, DSC, OTIER and ODSC requirements. 1710.114... AND GUARANTEES Loan Purposes and Basic Policies § 1710.114 TIER, DSC, OTIER and ODSC requirements. (a... of distribution borrowers whether applied on an annual or average basis, are a TIER of 1.25, DSC of...

  7. Black carbon quantification in charcoal-enriched soils by differential scanning calorimetry

    NASA Astrophysics Data System (ADS)

    Hardy, Brieuc; Cornelis, Jean-Thomas; Leifeld, Jens

    2015-04-01

    Black carbon (BC), the solid residue of the incomplete combustion of biomass and fossil fuels, is ubiquitous in soil and sediments, fulfilling several environmental services such as long-term carbon storage. BC is a particularly important terrestrial carbon pool due to its large residence time compared to thermally unaltered organic matter, which is largely attributed to its aromatic structure. However, BC refers to a wide range of pyrogenic products from partly charred biomass to highly condensed soot, with a degree of aromaticity and aromatic condensation varying to a large extend across the BC continuum. As a result, BC quantification largely depends on operational definitions, with the extraction efficiency of each method varying across the entire BC range. In our study, we investigated the adequacy of differential scanning calorimetry (DSC) for the quantification of BC in charcoal-enriched soils collected in the topsoil of pre-industrial charcoal kilns in forest and cropland of Wallonia, Belgium, where charcoal residues are mixed to uncharred soil organic matter (SOM). We compared the results to the fraction of the total organic carbon (TOC) resisting to K2Cr2O7 oxidation, another simple method often used for BC measurement. In our soils, DSC clearly discriminates SOM from chars. SOM is less thermally stable than charcoal and shows a peak maximum around 295°C. In forest and agricultural charcoal-enriched soils, three peaks were attributed to the thermal degradation of BC at 395, 458 and 523°C and 367, 420 and 502 °C, respectively. In cropland, the amount of BC calculated from the DSC peaks is closely related (slope of the linear regression = 0.985, R²=0.914) to the extra organic carbon content measured at charcoal kiln sites relative to the charcoal-unaffected adjacent soils, which is a positive indicator of the suitability of DSC for charcoal quantification in soil. The first BC peak, which may correspond to highly degraded charcoal, contributes to a

  8. Unspecific membrane protein-lipid recognition: combination of AFM imaging, force spectroscopy, DSC and FRET measurements.

    PubMed

    Borrell, Jordi H; Montero, M Teresa; Morros, Antoni; Domènech, Òscar

    2015-11-01

    In this work, we will describe in quantitative terms the unspecific recognition between lactose permease (LacY) of Escherichia coli, a polytopic model membrane protein, and one of the main components of the inner membrane of this bacterium. Supported lipid bilayers of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG) (3:1, mol/mol) in the presence of Ca(2+) display lateral phase segregation that can be distinguished by atomic force microscopy (AFM) as well as force spectroscopy. LacY shows preference for fluid (Lα) phases when it is reconstituted in POPE : POPG (3:1, mol/mol) proteoliposomes at a lipid-to-protein ratio of 40. When the lipid-to-protein ratio is decreased down to 0.5, two domains can be distinguished by AFM. While the upper domain is formed by self-segregated units of LacY, the lower domain is constituted only by phospholipids in gel (Lβ) phase. On the one hand, classical differential scanning calorimetry (DSC) measurements evidenced the segregation of a population of phospholipids and point to the existence of a boundary region at the lipid-protein interface. On the other hand, Förster Resonance Energy Transfer (FRET) measurements in solution evidenced that POPE is selectively recognized by LacY. A binary pseudophase diagram of POPE : POPG built from AFM observations enables to calculate the composition of the fluid phase where LacY is inserted. These results are consistent with a model where POPE constitutes the main component of the lipid-LacY interface segregated from the fluid bulk phase where POPG predominates.

  9. Reticulation of Aqueous Polyurethane Systems Controlled by DSC Method

    PubMed Central

    Cakic, Suzana; Lacnjevac, Caslav; Rajkovic, Milos B.; Raskovic, Ljiljana; Stamenkovic, Jakov

    2006-01-01

    The DSC method has been employed to monitor the kinetics of reticulation of aqueous polyurethane systems without catalysts, and with the commercial catalyst of zirconium (CAT®XC-6212) and the highly selective manganese catalyst, the complex Mn(III)-diacetylacetonemaleinate (MAM). Among the polyol components, the acrylic emulsions were used for reticulation in this research, and as suitable reticulation agents the water emulsible aliphatic polyisocyanates based on hexamethylendoisocyanate with the different contents of NCO-groups were employed. On the basis of DSC analysis, applying the methods of Kissinger, Freeman-Carroll and Crane-Ellerstein the pseudo kinetic parameters of the reticulation reaction of aqueous systems were determined. The temperature of the examination ranged from 50°C to 450°C with the heat rate of 0.5°C/min. The reduction of the activation energy and the increase of the standard deviation indicate the catalytic action of the selective catalysts of zirconium and manganese. The impact of the catalysts on the reduction of the activation energy is the strongest when using the catalysts of manganese and applying all the three afore-said methods. The least aberrations among the stated methods in defining the kinetic parameters were obtained by using the manganese catalyst.

  10. Study on biodegradation process of lignin by FTIR and DSC.

    PubMed

    Liu, Yang; Hu, Tianjue; Wu, Zhengping; Zeng, Guangming; Huang, Danlian; Shen, Ying; He, Xiaoxiao; Lai, Mingyong; He, Yibin

    2014-12-01

    The biodegradation process of lignin by Penicillium simplicissimum was studied to reveal the lignin biodegradation mechanisms. The biodegradation products of lignin were detected using Fourier transform infrared spectroscopy (FTIR), UV-Vis spectrophotometer, different scanning calorimeter (DSC), and stereoscopic microscope. The analysis of FTIR spectrum showed the cleavage of various ether linkages (1,365 and 1,110 cm(-1)), oxidation, and demethylation (2,847 cm(-1)) by comparing the different peak values in the corresponding curve of each sample. Moreover, the differences (Tm and ΔHm values) between the DSC curves indirectly verified the FTIR analysis of biodegradation process. In addition, the effects of adding hydrogen peroxide (H2O2) to lignin biodegradation process were analyzed, which indicated that H2O2 could accelerate the secretion of the MnP and LiP and improve the enzymes activity. What is more, lignin peroxidase and manganese peroxidase catalyzed the lignin degradation effectively only when H2O2 was presented.

  11. Analytic heuristics for a fast DSC-MRI

    NASA Astrophysics Data System (ADS)

    Virgulin, M.; Castellaro, M.; Marcuzzi, F.; Grisan, E.

    2014-03-01

    Hemodynamics of the human brain may be studied with Dynamic Susceptibility Contrast MRI (DSC-MRI) imaging. The sequence of volumes obtained exhibits a strong spatiotemporal correlation, that can be exploited to predict which measurements will bring mostly the new information contained in the next frames. In general, the sampling speed is an important issue in many applications of the MRI, so that the focus of many current researches is to study methods to reduce the number of measurement samples needed for each frame without degrading the image quality. For the DSC-MRI, the frequency under-sampling of single frame can be exploited to make more frequent space or time acquisitions, thus increasing the time resolution and allowing the analysis of fast dynamics not yet observed. Generally (and also for MRI), the recovery of sparse signals has been achieved by Compressed Sensing (CS) techniques, which are based on statistical properties rather than deterministic ones.. By studying analytically the compound Fourier+Wavelet transform, involved in the processes of reconstruction and sparsification of MR images, we propose a deterministic technique for a rapid-MRI, exploiting the relations between the wavelet sparse representation of the recovered and the frequency samples. We give results on real images and on artificial phantoms with added noise, showing the superiority of the methods both with respect to classical Iterative Hard Thresholding (IHT) and to Location Constraint Approximate Message Passing (LCAMP) reconstruction algorithms.

  12. Multivariate analysis of DSC-XRD simultaneous measurement data: a study of multistage crystalline structure changes in a linear poly(ethylene imine) thin film.

    PubMed

    Kakuda, Hiroyuki; Okada, Tetsuo; Otsuka, Makoto; Katsumoto, Yukiteru; Hasegawa, Takeshi

    2009-01-01

    A multivariate analytical technique has been applied to the analysis of simultaneous measurement data from differential scanning calorimetry (DSC) and X-ray diffraction (XRD) in order to study thermal changes in crystalline structure of a linear poly(ethylene imine) (LPEI) film. A large number of XRD patterns generated from the simultaneous measurements were subjected to an augmented alternative least-squares (ALS) regression analysis, and the XRD patterns were readily decomposed into chemically independent XRD patterns and their thermal profiles were also obtained at the same time. The decomposed XRD patterns and the profiles were useful in discussing the minute peaks in the DSC. The analytical results revealed the following changes of polymorphisms in detail: An LPEI film prepared by casting an aqueous solution was composed of sesquihydrate and hemihydrate crystals. The sesquihydrate one was lost at an early stage of heating, and the film changed into an amorphous state. Once the sesquihydrate was lost by heating, it was not recovered even when it was cooled back to room temperature. When the sample was heated again, structural changes were found between the hemihydrate and the amorphous components. In this manner, the simultaneous DSC-XRD measurements combined with ALS analysis proved to be powerful for obtaining a better understanding of the thermally induced changes of the crystalline structure in a polymer film.

  13. Probing lipid-cholesterol interactions in DOPC/eSM/Chol and DOPC/DPPC/Chol model lipid rafts with DSC and (13)C solid-state NMR.

    PubMed

    Fritzsching, Keith J; Kim, Jihyun; Holland, Gregory P

    2013-08-01

    The interaction between cholesterol (Chol) and phospholipids in bilayers was investigated for the ternary model lipid rafts, DOPC/eSM/Chol and DOPC/DPPC/Chol, with differential scanning calorimetry (DSC) and (13)C cross polarization magic angle spinning (CP-MAS) solid-state NMR. The enthalpy and transition temperature (Tm) of the Lα liquid crystalline phase transition from DSC was used to probe the thermodynamics of the different lipids in the two systems as a function of Chol content. The main chain (13)C (CH2)n resonance is resolved in the (13)C CP-MAS NMR spectra for the unsaturated (DOPC) and saturated (eSM or DPPC) chain lipid in the ternary lipid raft mixtures. The (13)C chemical shift of this resonance can be used to detect differences in chain ordering and overall interactions with Chol for the different lipid constituents in the ternary systems. The combination of DSC and (13)C CP-MAS NMR results indicate that there is a preferential interaction between SM and Chol below Tm for the DOPC/eSM/Chol system when the Chol content is ≤20mol%. In contrast, no preferential interaction between Chol and DPPC is observed in the DOPC/DPPC/Chol system above or below Tm. Finally, (13)C CP-MAS NMR resolves two Chol environments in the DOPC/eSM/Chol system below Tm at Chol contents >20mol% while, a single Chol environment is observed for DOPC/DPPC/Chol at all compositions.

  14. Determination of the thermo-mechanical properties in starch and starch/gluten systems at low moisture content - a comparison of DSC and TMA.

    PubMed

    Homer, Stephen; Kelly, Michael; Day, Li

    2014-08-08

    The impact of heating rate on the glass transition (Tg) and melting transitions observed by differential scanning calorimetry (DSC) on starch and a starch/gluten blend (80:20 ratio) at low moisture content was examined. The results were compared to those determined by thermo-mechanical analysis (TMA). Comparison with dynamic mechanical thermal analysis (DMTA) and phase transition analysis (PTA) is also discussed. Higher heating rates increased the determined Tg as well as the melting peak temperatures in both starch and the starch/gluten blend. A heating rate of 5°C/min gave the most precise value of Tg while still being clearly observed above the baseline. Tg values determined from the first and second DSC scans were found to differ significantly and retrogradation of starch biopolymers may be responsible. Tg values of starch determined by TMA showed good agreement with DSC results where the Tg was below 80°C. However, moisture loss led to inaccurate Tg determination for TMA analyses at temperatures above 80°C.

  15. An evaluation tool for FKBP12-dependent and -independent mTOR inhibitors using a combination of FKBP-mTOR fusion protein, DSC and NMR.

    PubMed

    Sekiguchi, Mitsuhiro; Kobashigawa, Yoshihiro; Kawasaki, Masashi; Yokochi, Masashi; Kiso, Tetsuo; Suzumura, Ken-ichi; Mori, Keitaro; Teramura, Toshio; Inagaki, Fuyuhiko

    2011-11-01

    Mammalian target of rapamycin (mTOR), a large multidomain protein kinase, regulates cell growth and metabolism in response to environmental signals. The FKBP rapamycin-binding (FRB) domain of mTOR is a validated therapeutic target for the development of immunosuppressant and anticancer drugs but is labile and insoluble. Here we designed a fusion protein between FKBP12 and the FRB domain of mTOR. The fusion protein was successfully expressed in Escherichia coli as a soluble form, and was purified by a simple two-step chromatographic procedure. The fusion protein exhibited increased solubility and stability compared with the isolated FRB domain, and facilitated the analysis of rapamycin and FK506 binding using differential scanning calorimetry (DSC) and solution nuclear magnetic resonance (NMR). DSC enabled the rapid observation of protein-drug interactions at the domain level, while NMR gave insights into the protein-drug interactions at the residue level. The use of the FKBP12-FRB fusion protein combined with DSC and NMR provides a useful tool for the efficient screening of FKBP12-dependent as well as -independent inhibitors of the mTOR FRB domain.

  16. DSC studies to evaluate the impact of bio-oil on cold flow properties and oxidation stability of bio-diesel.

    PubMed

    Garcia-Perez, Manuel; Adams, Thomas T; Goodrum, John W; Das, K C; Geller, Daniel P

    2010-08-01

    This paper describes the use of Differential Scanning Calorimetry (DSC) to evaluate the impact of varying mix ratios of bio-oil (pyrolysis oil) and bio-diesel on the oxidation stability and on some cold flow properties of resulting blends. The bio-oils employed were produced from the semi-continuous Auger pyrolysis of pine pellets and the batch pyrolysis of pine chips. The bio-diesel studied was obtained from poultry fat. The conditions used to prepare the bio-oil/bio-diesel blends as well as some of the fuel properties of these blends are reported. The experimental results suggest that the addition of bio-oil improves the oxidation stability of the resulting blends and modifies the crystallization behavior of unsaturated compounds. Upon the addition of bio-oil an increase in the oxidation onset temperature, as determined by DSC, was observed. The increase in bio-diesel oxidation stability is likely to be due to the presence of hindered phenols abundant in bio-oils. A relatively small reduction in DSC characteristic temperatures which are associated with cold flow properties was also observed but can likely be explained by a dilution effect.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  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. 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.

  5. 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.

  6. Differential scanning calorimetry of whole Escherichia coli treated with the antimicrobial peptide MSI-78 indicate a multi-hit mechanism with ribosomes as a novel target.

    PubMed

    Brannan, Alexander M; Whelan, William A; Cole, Emma; Booth, Valerie

    2015-01-01

    Differential Scanning Calorimetry (DSC) of intact Escherichia coli (E. coli) was used to identify non-lipidic targets of the antimicrobial peptide (AMP) MSI-78. The DSC thermograms revealed that, in addition to its known lytic properties, MSI-78 also has a striking effect on ribosomes. MSI-78's effect on DSC scans of bacteria was similar to that of kanamycin, an antibiotic drug known to target the 30S small ribosomal subunit. An in vitro transcription/translation assay helped confirm MSI-78's targeting of ribosomes. The scrambled version of MSI-78 also affected the ribosome peak of the DSC scans, but required greater amounts of peptide to cause a similar effect to the unscrambled peptide. Furthermore, the effect of the scrambled peptide was not specific to the ribosomes; other regions of the DSC thermogram were also affected. These results suggest that MSI-78's effects on E. coli are at least somewhat dependent on its particular structural features, rather than a sole function of its overall charge and hydrophobicity. When considered along with earlier work detailing MSI-78's membrane lytic properties, it appears that MSI-78 operates via a multi-hit mechanism with multiple targets.

  7. Improving the dispersity of detonation nanodiamond: differential scanning calorimetry as a new method of controlling the aggregation state of nanodiamond powders.

    PubMed

    Korobov, Mikhail V; Volkov, Dmitry S; Avramenko, Natalya V; Belyaeva, Lubov' A; Semenyuk, Pavel I; Proskurnin, Mikhail A

    2013-02-21

    Detonation nanodiamond (ND) is a suitable source material to produce unique samples consisting of almost uniform diamond nanocrystals (d = 3-5 nm). Such samples exist in the form of long stable aqueous dispersions with narrow size distribution of diamond particles. The material is finding ever increasing application in biomedicine. The major problem in producing monodispersed diamond colloids lies in the necessity of deagglomeration of detonation soot and/or removing of clusters formed by already isolated core particles in dry powders. To do this one must have an effective method to monitor the aggregation state or dispersity of powders and gels prior to the preparation of aqueous dispersions. In the absence of dispersity control at various stages of preparation the reproducibility of properties of existing ND materials is poor. In this paper we introduce differential scanning calorimetry (DSC) as a new tool capable to distinguish the state of aggregation in dry and wetted ND materials and to follow changes in this state under different types of treatment. Samples with identical X-ray diffraction patterns (XRD) and high resolution transmission electron microscopy (HRTEM) images gave visibly different DSC traces. Strong correlation was found between dynamic light scattering (DLS) data for colloids and DSC parameters for gels and powders of the same material. Based on DSC data we improved dispersity of existing ND materials and isolated samples with the best possible DSC parameters. These were true monodispersed easily dispersible fractions of ND particles with diameters of ca. 3 nm.

  8. Differential scanning calorimetry of whole Escherichia coli treated with the antimicrobial peptide MSI-78 indicate a multi-hit mechanism with ribosomes as a novel target

    PubMed Central

    Brannan, Alexander M.; Whelan, William A.; Cole, Emma

    2015-01-01

    Differential Scanning Calorimetry (DSC) of intact Escherichia coli (E. coli) was used to identify non-lipidic targets of the antimicrobial peptide (AMP) MSI-78. The DSC thermograms revealed that, in addition to its known lytic properties, MSI-78 also has a striking effect on ribosomes. MSI-78’s effect on DSC scans of bacteria was similar to that of kanamycin, an antibiotic drug known to target the 30S small ribosomal subunit. An in vitro transcription/translation assay helped confirm MSI-78’s targeting of ribosomes. The scrambled version of MSI-78 also affected the ribosome peak of the DSC scans, but required greater amounts of peptide to cause a similar effect to the unscrambled peptide. Furthermore, the effect of the scrambled peptide was not specific to the ribosomes; other regions of the DSC thermogram were also affected. These results suggest that MSI-78’s effects on E. coli are at least somewhat dependent on its particular structural features, rather than a sole function of its overall charge and hydrophobicity. When considered along with earlier work detailing MSI-78’s membrane lytic properties, it appears that MSI-78 operates via a multi-hit mechanism with multiple targets. PMID:26713257

  9. 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.

  10. Overriding "doing wrong" and "not doing right": validation of the Dispositional Self-Control Scale (DSC).

    PubMed

    Ein-Gar, Danit; Sagiv, Lilach

    2014-01-01

    We present the Dispositional Self-Control (DSC) Scale, which reflects individuals' tendency to override 2 types of temptations, termed doing wrong and not doing right. We report a series of 5 studies designed to test the reliability and validity of the scale. As hypothesized, high DSC predicts distant future orientation and low DSC predicts deviant behaviors such as aggression, alcohol misuse, and aberrant driving. DSC also predicts task performance among resource-depleted participants. Taken together, these findings suggest that the DSC Scale could be a useful tool toward further understanding the role of personality in overcoming self-control challenges.

  11. 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.

  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. 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.

  14. TG-DSC-FTIR Analysis of Cyanobacteria Pyrolysis

    NASA Astrophysics Data System (ADS)

    Supeng, Luo; Guirong, Bao; Hua, Wang; Fashe, Li; Yizhe, Li

    Pyrolysis of cyanobacteria from Dianchi lake was investigated by TG-DSC-FTIR analysis at different heating rates (10, 20, 40°C/min). The results indicated that the pyrolysis of cyanobacteria can be divided into four stages: evaporation, depolymerization, devolatilization and carbonization. Meanwhile, the initial weight-loss temperature, weight-loss extreme position, endothermic and exothermic peaks were moved to higher temperature with the increaseing of the heating rate. The kinetic analysis was made with Popescu method. It indicated that the best kinetic model for the pyrolysis of cyanobacteria was the cylindrical symmetry of the phase boundary reaction model. The main pyrolysis gases checked with real-time online FTIR were HCN, NH3, CO, CO2, water vapor and hydrocarbons.

  15. DSC and Raman studies of silver borotellurite glasses

    NASA Astrophysics Data System (ADS)

    Kaur, Amandeep; Khanna, Atul; Gonzàlez, Fernando

    2016-05-01

    Silver borotellurite glasses of composition: xAg2O-yB2O3-(100-x-y)TeO2 (x=20-mol%, y = 0, 10, 20 and 30-mol%) were prepared and characterized by density, X-ray diffraction (XRD), differential scanning calorimetry, and Raman spectroscopy. XRD confirmed the amorphous structure of all samples. Density of glasses decreases while the glass transition temperature increases with increase in B2O3 content from 10 to 30-mol%. Raman study shows that coordination number of Te with oxygen decreases steadily from 3.42 to 3.18 on adding B2O3 due to the transformation of TeO4 into TeO3 units.

  16. 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.

  17. Thermal properties and optimization of process parameters for the growth of silver thiogallate crystal by differential scanning calorimetry

    NASA Astrophysics Data System (ADS)

    He, Zhiyu; Zhao, Beijun; Zhu, Shifu; Chen, Baojun; Huang, Wei

    2014-09-01

    In present work, thermal properties of silver thiogallate (AgGaS2) crystal were investigated by means of differential scanning calorimetry (DSC) measurements performed at different heating and cooling rates. The DSC results confirmed that the melting point was 1249 K with a slight change around 5 K and that the nucleation temperature varied from 1183 K to 1218 K. The supercooling temperature was evaluated in the range 37.69 K to 62.46 K which was considered to be harmful for the single nucleus formation at the beginning of crystal growth. The activation energy E and the pre-exponential factor A were also calculated using different isoconversional methods, namely Kissinger-Akahira-Sunose (KAS) method and Flynn-Wall-Ozawa (FWO) method, and the results showed good agreement with each other. According to the results of DSC, a larger temperature gradient up to 30 K/cm was utilized to suppress the formation and growth of multi nuclei and a rapid cooling rate 25 K/min was applied to minimize the second-phase precipitates during the process of crystal growth. Finally, an integral and transparent AgGaS2 single crystal with diameter of 22 mm and the length of 55 mm was obtained.

  18. Automatic twin vessel recrystallizer. Effective purification of acetaminophen by successive automatic recrystallization and absolute determination of purity by DSC.

    PubMed

    Nara, Osamu

    2011-01-24

    I describe an interchangeable twin vessel (J, N) automatic glass recrystallizer that eliminates the time-consuming recovery and recycling of crystals for repeated recrystallization. The sample goes in the dissolution vessel J containing a magnetic stir-bar K; J is clamped to the upper joint H of recrystallizer body D. Empty crystallization vessel N is clamped to the lower joint M. Pure solvent is delivered to the dissolution vessel and the crystallization vessel via the head of the condenser A. Crystallization vessel is heated (P). The dissolution reservoir is stirred and heated by the solvent vapor (F). Continuous outflow of filtrate E out of J keeps N at a stable boiling temperature. This results in efficient dissolution, evaporation and separation of pure crystals Q. Pure solvent in the dissolution reservoir is recovered by suction. Empty dissolution and crystallization vessels are detached. Stirrer magnet is transferred to the crystallization vessel and the role of the vessels are then reversed. Evacuating mother liquor out of the upper twin vessel, the apparatus unit is ready for the next automatic recrystallization by refilling twin vessels with pure solvent. We show successive automatic recrystallization of acetaminophen from diethyl ether obtaining acetaminophen of higher melting temperatures than USP and JP reference standards by 8× automatic recrystallization, 96% yield at each stage. Also, I demonstrate a novel approach to the determination of absolute purity by combining the successive automatic recrystallization with differential scanning calorimetry (DSC) measurement requiring no reference standards. This involves the measurement of the criterial melting temperature T(0) corresponding to the 100% pure material and quantitative ΔT in DSC based on the van't Hoff law of melting point depression. The purity of six commercial acetaminophen samples and reference standards and an eight times recrystallized product evaluated were 98.8 mol%, 97.9 mol%, 99

  19. Inhibitors of thermally induced burn incidents – characterization by microbiological procedure, electrophoresis, SEM, DSC and IR spectroscopy.

    PubMed

    Pielesz, Anna; Machnicka, Alicja; Gawłowski, Andrzej; Fabia, Janusz; Sarna, Ewa; Biniaś, Włodzimierz

    2015-07-07

    Differential scanning calorimetry (DSC) and thermogravimetric (TGA) investigations, acetate electrophoresis (CAE), Fourier-transform infrared spectrometry (FTIR), scanning electron microscopy (SEM) analysis and microbiological procedures were all carried out after heating the samples to a temperature sufficient for simulating a burn incident. In particular, the purpose of the present study was to analyze the effect of antioxidants, such as fucoidan from brown seaweed and flame-retardant cyclic organophosphates and phosphonates, on an organic chicken skin that gets changed by a burn incident. DSC was considered to be a useful tool in assessing in vitro temperature-mediated cross-linking; an innovative analytical conclusion was obtained from the experimentation described in the paper. FTIR tests revealed that heating a dry organic chicken skin to the boiling point leads to the disappearance of a wide band in the 1650-1550 cm(-1) area or the conversion of a band, which may be attributed to the intermolecular β-sheet aggregates. Fucoidan from brown seaweed and flame-retardant cyclic organophosphates and phosphonates probably bind with the collagen that is changed by the burn (in addition to the influence of antioxidant solutions on samples of a blank or not boiled organic chicken skin) incident forming a polymer film with the collagen of the chicken skin surface (SEM analysis), decreasing the aggregation process and native collagen recovery. Good bacteriostatic properties were determined for fucoidan samples from brown seaweed and flame-retardant cyclic organophosphates and phosphonates against the pathogenic bacteria Escherichia coli and Staphylococcus aureus. Thus, it was observed that the fucoidan incorporated into collagen films can be used as a therapeutically active biomaterial that speeds up the wound-healing process.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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

  5. The enthalpy of transformation of Ca(OH)2-I (portlandite) to Ca(OH)2-II (EuI2 structure) by low-temperature DSC

    NASA Astrophysics Data System (ADS)

    Schoenitz, M.; Navrotsky, A.; Leinenweber, K.

    Thermodynamic properties of high-pressure minerals that are not recoverable from synthesis experiments by conventional quenching methods (``unquenchable'' phases) usually are calculated from equation of state data and phase diagram topologies. The present study shows that, with cryogenic methods of recovery and sample treatment, phases with a suitable decomposition rate can be made accessible to direct thermodynamic measurements. A set of samples of Ca(OH)2-II has been synthesized in a multianvil device and subsequently recovered by cooling the high-pressure assembly with liquid nitrogen. Upon heating from liquid nitrogen to room temperature, the material transformed back to Ca(OH)2-I. The heat effect of this backtransformation was measured by differential scanning calorimetry. A commercial differential scanning calorimeter (Netzsch DSC 404), modified to allow sample loading at liquid nitrogen temperature was used to heat the material from -150 to +200°C at rates varying between 5 and 15°Cmin-1. The transformation started around -50°C very gradually, and peaked at about 0°C. To obtain a baseline correction, each sample was scanned under exactly the same conditions after the backtransformation was complete. Because of the relative sluggishness, onset and offset temperatures were not well defined as compared to fast (e.g., melting) reactions. To aid in integration, the resulting signals were successfully fitted using a generic asymmetric peak model. The enthalpy of backtransformation was determined to be ΔH=-10.37+/-0.50kJ mol-1. From previous in situ X-ray diffraction experiments, the location of the direct transformation in P-T space has been constrained to 5.7+/-0.4GPa at 500°C (Kunz etal. 1996). With the reaction volume known from the same study, and assuming that ΔCp of the transformation remains negligible between the conditions of our measurements and 500°C, our result gives an estimate of the entropy of transition and the P-T slope of the reaction

  6. Profiles in Leadership: Donald E. Francke, MSc, DSc (Hon)

    PubMed Central

    Stevenson, James G.; Beham, Rachel E.; Weber, Robert J.

    2013-01-01

    The Director’s Forum series is designed to guide pharmacy leaders in establishing patient-centered services in hospitals and health systems. August 2013 marked the 50th anniversary of the publication of the Mirror to Hospital Pharmacy, the results of a federally funded comprehensive study of pharmacy services in the United States. The late Don E. Francke, MS, DSc, was the lead author of the Mirror and the principal investigator for the US Public Health Service grant W-45. To celebrate the anniversary of the Mirror, the Director’s Forum is profiling the leadership styles of Drs. Latiolais and Francke. September’s article highlighted Dr. Clifton J. Latiolais; this month’s Director’s Forum reviews Dr. Francke’s biography and key career accomplishments, describes his leadership philosophy, and translates that philosophy to today’s health care challenges. Don’s influence on health system pharmacy serves as an example of effective leadership. This historical perspective provides directors of pharmacy a valuable leadership view as they develop strategies to enhance patient-centered pharmacy services. PMID:24421553

  7. Thermal: Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), and Polarized Microscopy Instrumentation for the Analysis of Field-Controlled Anisotropic Nanomaterials

    DTIC Science & Technology

    2014-11-14

    figure 1.2.1, right). The discovery TGA furnace design employs a silicon carbide ( SiC ) inner chamber. Four halogen lamps surrounded by a water...amplification,(13, 17) self-phase modulation (18, 19), and new nonlinear phenomena such as the nonlinear optical mirror ,(20) and the mirrorless optical

  8. Surfactant softening of plant leaf cuticle model wax--a Differential Scanning Calorimetry (DSC) and Quartz Crystal Microbalance with Dissipation (QCM-D) study.

    PubMed

    Fagerström, Anton; Kocherbitov, Vitaly; Westbye, Peter; Bergström, Karin; Arnebrant, Thomas; Engblom, Johan

    2014-07-15

    The aim was to quantify the softening effect that two surfactants (C10EO7 and C8G1.6) have on a plant leaf cuticle model wax. Effects on the thermotropic phase behavior and fluidity of the wax (C22H45OH/C32H66/H2O) were determined. The model wax is crystalline at ambient conditions, yet it is clearly softened by the surfactants. Both surfactants decreased the transition temperatures in the wax and the G″/G' ratio of the wax film increased in irreversible steps following surfactant exposure. C10EO7 has a stronger fluidizing effect than C8G1.6 due to stronger interaction with the hydrophobic waxes. Intracuticular waxes (IW) comprise both crystalline and amorphous domains and it has previously been proposed that the fluidizing effects of surfactants are due to interactions with the amorphous parts. New data suggests that this may be a simplification. Surfactants may also absorb in crevices between crystalline domains. This causes an irreversible effect and a softer cuticle wax.

  9. Physicochemical aging mechanisms in soil organic matter assessed by NMR and DSC

    NASA Astrophysics Data System (ADS)

    Schwarz, J.; Jaeger, A.; Bertmer, M.; Schlichting, A.; Leinweber, P.; Schaumann, G. E.

    2009-04-01

    Soil organic matter (SOM) controls a variety of processes occurring at biogeochemical interfaces acting as a highly dynamic matrix. Results from previous studies showed that SOM undergoes physicochemical matrix aging. It was hypothesized that the formation and disruption of water molecule bridges are responsible for this aging process. The objective of this study was to evaluate this hypothesis using three peat samples from different sample sites in Germany: a peat from Rhinluch, 60 km northwest of Berlin, a black peat and a white peat from Fuhrberg near Hannover. The composition determined by pyrolysis field ionisation mass spectrometry was similar for the Rhinluch peat and the Fuhrberg black peat, but showed a distinctly higher carbohydrate content for the Fuhrberg white peat. To elucidate mechanisms of physicochemical matrix aging and to evaluate the hypothesis of water molecule bridges we carried out heating-cooling events in hermetically sealed containers and measured the response by NMR and DSC as a function of time. The heating-cooling event started with heating for 10 minutes at 110 °C followed by rapid cooling and isothermal storage at 19 °C for at least four months. All peats show a non-reversing step transition between 40 °C and 65 °C similar to transitions observed in previous studies. The black peat from Fuhrberg showed an additional step transition between 35 °C and 45 °C. The temperature of the non-reversing step transition immediately decreased by 25 °C in response to the heating-cooling event and slowly re-increased upon isothermal storage within several months. The temperature of the reversing transition showed a similar behaviour but not as strongly as the non-reversing transition. The proton NMR in combination with line separation into Lorentz and Gauss lines was used to differentiate between the different kinds of water. In dependence of the water bridge status the portions of these lines on the total wide line spectrum change; at a

  10. 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.

  11. Examination of fluorination effect on physical properties of saturated long-chain alcohols by DSC and Langmuir monolayer.

    PubMed

    Nakahara, Hiromichi; Nakamura, Shohei; Okahashi, Yoshinori; Kitaguchi, Daisuke; Kawabata, Noritake; Sakamoto, Seiichi; Shibata, Osamu

    2013-02-01

    Partially fluorinated long-chain alcohols have been newly synthesized from a radical reaction, which is followed by a reductive reaction. The fluorinated alcohols have been investigated by differential scanning calorimetry (DSC) and compression isotherms in a Langmuir monolayer state. Their melting points increase with an increase in chain length due to elongation of methylene groups. However, the melting points for the alcohols containing shorter fluorinated moieties are lower than those for the typical hydrogenated fatty alcohols. Using the Langmuir monolayer technique, surface pressure (π)-molecular area (A) and surface potential (ΔV)-A isotherms of monolayers of the fluorinated alcohols have been measured in the temperature range from 281.2 to 303.2K. In addition, a compressibility modulus (Cs(-1)) is calculated from the π-A isotherms. Four kinds of the alcohol monolayers show a phase transition (π(eq)) from a disordered to an ordered state upon lateral compression. The π(eq) values increase linearly with increasing temperatures. A slope of π(eq) against temperature for the alcohols with shorter fluorocarbons is unexpectedly larger than that for the corresponding fatty alcohols. Generally, fluorinated amphiphiles have a greater thermal stability (or resistance), which is a characteristic of highly fluorinated or perfluorinated compounds. Herein, however, the alcohols containing perfluorobutylated and perfluorohexylated chains show the irregular thermal behavior in both the solid and monolayer states.

  12. 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.

  13. 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.

  14. Study of the Crystalline Morphology Evolution of PET and PET/PC Blends by Time-resolved Synchrotron Small Angle X-ray Scattering (SAXS) and DSC

    SciTech Connect

    Barbosa, Irineu; Larocca, Nelson M.; Hage, Elias; Plivelic, Tomas S.; Torriani, Iris L.; Mantovani, Gerson L.

    2009-01-29

    Isothermal melt crystallization of poly(ethylene terephthalate)(PET) and PET/PC (polycarbonate) blend, with and without a transesterification catalyst, was studied by time-resolved small-angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC) in order to achieve the variation of the morphological parameters throughout the whole crystallization time. For neat PET, the catalyst promotes a decrease of the crystal lamellar thickness but for the blend no variations were observed. The effect of incorporation of catalyst in crystallization kinetics was very distinct in PET pure and the blend: in the former the catalyst leads to an increase of this kinetics while for the latter it was observed a decreasing.

  15. 47 CFR 80.103 - Digital selective calling (DSC) operating procedures.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Digital selective calling (DSC) operating procedures. 80.103 Section 80.103 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... Procedures-General § 80.103 Digital selective calling (DSC) operating procedures. (a) Operating...

  16. 47 CFR 80.103 - Digital selective calling (DSC) operating procedures.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Digital selective calling (DSC) operating... Procedures-General § 80.103 Digital selective calling (DSC) operating procedures. (a) Operating procedures..., “Operational Procedures for the Use of Digital Selective-Calling Equipment in the Maritime Mobile...

  17. 47 CFR 80.359 - Frequencies for digital selective calling (DSC).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Frequencies for digital selective calling (DSC). 80.359 Section 80.359 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... for digital selective calling (DSC). (a) General purpose calling. The following table describes...

  18. 47 CFR 80.103 - Digital selective calling (DSC) operating procedures.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Digital selective calling (DSC) operating procedures. 80.103 Section 80.103 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... Procedures-General § 80.103 Digital selective calling (DSC) operating procedures. (a) Operating...

  19. 47 CFR 80.359 - Frequencies for digital selective calling (DSC).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Frequencies for digital selective calling (DSC... for digital selective calling (DSC). (a) General purpose calling. The following table describes the...-R Recommendation M.541-9, “Operational Procedures for the Use of Digital Selective-Calling...

  20. 47 CFR 80.103 - Digital selective calling (DSC) operating procedures.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Digital selective calling (DSC) operating... Procedures-General § 80.103 Digital selective calling (DSC) operating procedures. (a) Operating procedures..., “Operational Procedures for the Use of Digital Selective-Calling Equipment in the Maritime Mobile...

  1. 47 CFR 80.359 - Frequencies for digital selective calling (DSC).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Frequencies for digital selective calling (DSC). 80.359 Section 80.359 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... for digital selective calling (DSC). (a) General purpose calling. The following table describes...

  2. 47 CFR 80.103 - Digital selective calling (DSC) operating procedures.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Digital selective calling (DSC) operating procedures. 80.103 Section 80.103 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... Procedures-General § 80.103 Digital selective calling (DSC) operating procedures. (a) Operating...

  3. 47 CFR 80.359 - Frequencies for digital selective calling (DSC).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Frequencies for digital selective calling (DSC). 80.359 Section 80.359 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... for digital selective calling (DSC). (a) General purpose calling. The following table describes...

  4. 47 CFR 80.359 - Frequencies for digital selective calling (DSC).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Frequencies for digital selective calling (DSC... for digital selective calling (DSC). (a) General purpose calling. The following table describes the...-R Recommendation M.541-9, “Operational Procedures for the Use of Digital Selective-Calling...

  5. Quantifying Natural Organic Matter with Calorimetry - assessing system complexity to build a central view C stability

    NASA Astrophysics Data System (ADS)

    Liles, G. C.; Bower, J.; Henneberry, Y.; Horwath, W. R.

    2010-12-01

    Characterizing the status and stability of natural organic matter (NOM) is central to understanding the flux, attenuation and function of C in the biosphere. A diversity of stabilizing factors (climate, mineralogy, chemical recalcitrance) have required a range of analytical approaches and methods that are site or discipline specific making unified assessments difficult. Aggregated, these efforts support our working models of NOM as a dynamic body but, overall, lack analytical simplicity and reproducibility. In particular, the robustness and resolution to assess NOM across systems of increasing complexity is lacking. Calorimetry has been central to chemistry and material science characterizing a broad range of organic and inorganic materials and their mixtures illustrating composition, purity and stability. Differential scanning calorimetry - thermogravimetry (DSC-TG) provides the flexibility and resolution to quantify the complexity found within NOM with precise quantification of material mass loss (TG) and energetic (DSC) under controlled atmospheric and heating conditions. DSC-TG is data rich providing a range of qualitative and quantitative metrics: peak shape, exothermic energy yield, mass loss, and determination of enthalpy, to characterize NOM stability from low (dissolved organic carbon - DOC) through high (compost and soils) molecular weights (MW) at increasing levels of organo-metallic complexity. Our research investigates the influence of biochemical recalcitrance and its alteration by oxides employing three natural systems of varying complexity as experimental models: aquatic - DOC and DOC with metal flocculants (low MW - low complexity), compost - processed with and without metal oxides (mixed MW - increasing complexity) and forest soils - under varying management and litter inputs (mixed MW - most complexity). Samples were analyzed by DSC-TG (zero-air - 20 C/min - ambient to > 800C) and assessed for three temperature/exothermic reaction regions (200

  6. 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.

  7. Estimation of drug solubility in polymers via differential scanning calorimetry and utilization of the fox equation.

    PubMed

    Haddadin, Raja; Qian, Feng; Desikan, Sridhar; Hussain, Munir; Smith, Ronald L

    2009-01-01

    The solubility of drugs in polyethylene glycol 400 (PEG 400) was estimated and rank ordered using a differential scanning calorimetry (DSC) method and the Fox Equation. Drug-polymer binary mixtures of six compounds (Ibuprofen, Indomethacin, Naproxen, and three proprietary compounds: PC-1 through PC-3) with PEG 400 were heat treated using a three-cycle DSC method to establish a correlation between equilibrium solubility and temperature. Thermal events such as heat of fusion, heat of recrystallization and glass transition temperature, T(g), were used to calculate the drug solubility at multiple higher temperatures through the Fox Equation. Subsequently, a van't Hoff plot was constructed to estimate the drug solubility at room temperature, and the values were compared with those measured by HPLC. With the exception of Naproxen, room temperature solubilities of the remaining drug compounds in PEG 400 were determined by this thermal method approach, and compared with those measured by HPLC: 26.7% vs. 24.7% for Ibuprofen, 5.8% vs. 9.6% for Indomethacin, 3.1 % vs. 1.5% for PC-1, 2.3% vs. 1.3% for PC-2, and 1.4% vs. 0.2% for PC-3 in PEG 400. There was good concordance in solubility rank order estimates between the two methods. These collective results support the potential utility of the thermal method as an alternative to other methods for estimation of drug solubility in polymers which is an important determinant in the design of physically-stable amorphous systems.

  8. 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.}

  9. DSC, X-ray and FTIR studies of a gemfibrozil/dimethyl-β-cyclodextrin inclusion complex produced by co-grinding.

    PubMed

    Aigner, Z; Berkesi, O; Farkas, G; Szabó-Révész, P

    2012-01-05

    The steps of formation of an inclusion complex produced by the co-grinding of gemfibrozil and dimethyl-β-cyclodextrin were investigated by differential scanning calorimetry (DSC), X-ray powder diffractometry (XRPD) and Fourier transform infrared (FTIR) spectroscopy with curve-fitting analysis. The endothermic peak at 59.25°C reflecting the melting of gemfibrozil progressively disappeared from the DSC curves of the products on increase of the duration of co-grinding. The crystallinity of the samples too gradually decreased, and after 35min of co-grinding the product was totally amorphous. Up to this co-grinding time, XRPD and FTIR investigations indicated a linear correlation between the cyclodextrin complexation and the co-grinding time. After co-grinding for 30min, the ratio of complex formation did not increase. These studies demonstrated that co-grinding is a suitable method for the complexation of gemfibrozil with dimethyl-β-cyclodextrin. XRPD analysis revealed the amorphous state of the gemfibrozil-dimethyl-β-cyclodextrin product. FTIR spectroscopy with curve-fitting analysis may be useful as a semiquantitative analytical method for discriminating the molecular and amorphous states of gemfibrozil.

  10. Lyotropic model membrane structures of hydrated DPPC: DSC and small-angle X-ray scattering studies of phase transitions in the presence of membranotropic agents

    NASA Astrophysics Data System (ADS)

    Bulavin, L. A.; Soloviov, D. V.; Gordeliy, V. I.; Svechnikova, O. S.; Krasnikova, A. O.; Kasian, N. A.; Vashchenko, O. V.; Lisetski, L. N.

    2015-06-01

    Multibilayer structures of hydrated phospholipids, often considered as model biological membranes, are, from the physical viewpoint, lyotropic liquid crystalline systems undergoing temperature-induced mesomorphic phase transitions. Effects of silver nitrate and urocanic acid on lyotropic phase states of hydrated L-α-dipalmitoylphosphatidylcholine (DPPC) have been studied by small-angle X-ray scattering and differential scanning calorimetry (DSC). Both methods show increase of the main phase-transition temperature (Tm) of hydrated DPPC upon introduction of AgNO3 or urocanic acid, decrease of pre-transition temperature (Tp) in the presence of urocanic acid and its increase in the presence of AgNO3. Thus, urocanic acid widened the ripple-phase temperature region. Silver nitrate caused the appearance of an additional high-temperature peak on DSC thermograms, evidencing phase separation in the system. Both agents caused minor effects on DPPC lipid bilayer repeat distance (D) in gel phase, but resulted in noticeable increase of D in the liquid crystal phase with temperature as compared to undoped DPPC structures.

  11. An experimental study of the (Ti-6Al-4V)-xH phase diagram using in situ synchrotron XRD and TGA/DSC techniques.

    SciTech Connect

    Sun, Pei; Fang, Z. Zak; Koopman, Mark; Paramore, James D.; Chandran, K. S. Ravi; Ren, Yang; Lu, Jun

    2015-02-01

    Hydrogen has been investigated for decades as a temporary alloying element to refine the microstructure of Ti-6Al-4V, and is now being used in a novel powder metallurgy method known as "hydrogen sintering and phase transformation". Pseudo-binary phase diagrams of (Ti-6Al-4V)-xH have been studied and developed, but are not well established due to methodological limitations. In this paper, in situ studies of phase transformations during hydrogenation and dehydrogenation of (Ti-6Al-4V)-xH alloys were conducted using high-energy synchrotron X-ray diffraction (XRD), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The eutectoid phase transformation of β ↔ α + δ was observed in the (Ti-6Al-4V)-xH alloy via in situ synchrotron XRD at 211 °C with a hydrogen concentration of 37.5 at.% (measured using TGA-DSC). The relationships of hydrogen composition to partial pressure and temperature were investigated in the temperature range 450-900°C. Based on these results, a partial pseudo-binary phase diagram of (Ti-6Al-4V)-xH is proposed for hydrogen compositions up to 60 at.% in the temperature range 100-900°C. Using the data collected in real time under controlled parameters of temperature, composition and hydrogen partial pressure, this work characterizes relevant phase transformations and microstructural evolution for practical titanium-hydrogen technologies of Ti-6Al-4V.

  12. 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.

  13. 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.

  14. Impact of maltodextrins and antistaling enzymes on the differential scanning calorimetry staling endotherm of baked bread doughs.

    PubMed

    Defloor, I; Delcour, J A

    1999-02-01

    Different concentrations (1.2-3.6%) of maltodextrin preparations with average degrees of polymerization (DP) varying between 4 and 66 reduced the differential scanning calorimetry (DSC) staling endotherm in baked and stored (7 days, 23 degrees C) bread doughs from 3.4 mJ/mg to values within a 3.0-1.9 mJ/mg range. Commercial enzymes used in industrial practice as antistaling agents for bread also reduced amylopectin retrogradation. This suggested that the maltodextrins used are promising antistaling components and that the staling of bread and amylopectin retrogradation are related phenomena. In addition, the results obtained suggest that starch hydrolysis products resulting from enzymic attack may well be responsible for the antistaling effect induced by antistaling enzymes.

  15. Starch transitions of different gluten free flour doughs determined by dynamic thermal mechanical analysis and differential scanning calorimetry.

    PubMed

    Moreira, R; Chenlo, F; Arufe, S

    2015-01-01

    Gluten-free flour doughs (three from different maize varieties and one from chestnut fruit) processed at the same consistency level (1.10 ± 0.07 N m) with different water absorption were used to determine the starch transitions by means of two different experimental techniques, differential scanning calorimetry (DSC) and dynamic thermal mechanical analysis (DMTA). The ranges of temperatures of gelatinization (G), amylopectin melting (M1), amylose-lipid complexes melting (M2) and amylose melting (M3) for all tested flour doughs were determined by both experimental techniques with acceptable agreement between them. The starch transitions in DMTA were determined by means of the elastic modulus (G, M1 and M2) or damping factor (G, M3) evolution with temperature. The temperatures and enthalpies of the transitions depended on water content, the nature and characteristics (mainly damaged starch) of the starch and the presence of other compounds (mainly lipid and sugars) in the flour doughs.

  16. 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.

  17. 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).

  18. 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.

  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. 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

  1. Biomass pyrolysis and combustion integral and differential reaction heats with temperatures using thermogravimetric analysis/differential scanning calorimetry.

    PubMed

    Shen, Jiacheng; Igathinathane, C; Yu, Manlu; Pothula, Anand Kumar

    2015-06-01

    Integral reaction heats of switchgrass, big bluestem, and corn stalks were determined using thermogravimetric analysis/differential scanning calorimetry (TGA/DSC). Iso-conversion differential reaction heats using TGA/DSC pyrolysis and combustion of biomass were not available, despite reports available on heats required and released. A concept of iso-conversion differential reaction heats was used to determine the differential reaction heats of each thermal characteristics segment of these materials. Results showed that the integral reaction heats were endothermic from 30 to 700°C for pyrolysis of switchgrass and big bluestem, but they were exothermic for corn stalks prior to 587°C. However, the integral reaction heats for combustion of the materials followed an endothermic to exothermic transition. The differential reaction heats of switchgrass pyrolysis were predominantly endothermic in the fraction of mass loss (0.0536-0.975), and were exothermic for corn stalks (0.0885-0.850) and big bluestem (0.736-0.919). Study results provided better insight into biomass thermal mechanism.

  2. 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.

  3. 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).

  4. 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.

  5. 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.

  6. CALOR2012 XVth International Conference on Calorimetry in High Energy Physics

    SciTech Connect

    Akchurin, Nural .

    2015-05-04

    The International Conferences on Calorimetry in High Energy Physics, or the CALOR series, have always been where the calorimeter experts come together to review the state of calorimetry and bring forth new ideas every two years. The fteenth conference, CALOR2012, in Santa Fe was no exception. Although they were built roughly a decade ago, we are now witnessing the exceptional power of the LHC calorimeters and the crucial role they have been playing in the discovery of the 125 GeV Higgs-like boson. As we ruminate on the coming generation of experiments at the next (linear) collider and on the upgrades at the LHC, we are heartened by the substantial advances we made in calorimetry in the last decade. These advances will certainly help uncover new physics in the years to come, not only at colliders but also in astroparticle experiments that take advantage of natural elements such as air, water, and ice. The proceedings were published by the IOP in Journal of Physics, Vol 404 2011. The conference web site is calor2012.ttu.edu.

  7. 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.

  8. Insights into composition/structure/function relationships of Doxil® gained from "high-sensitivity" differential scanning calorimetry.

    PubMed

    Wei, Xiaohui; Cohen, Rivka; Barenholz, Yechezkel

    2016-07-01

    Thermotropic behavior of Doxil® and its generic, Lipodox®, was characterized using "high-sensitivity" differential scanning calorimetry (DSC). This is the first report that two distinct endotherms were observed in Doxil and Lipodox upon heating. The first (Tm at 51±2°C) is broad and of low enthalpy, representing the membrane lipid phase transition, which occurs despite having high (38mole%) cholesterol. The second (Tm at ∼70°C) is narrow, representing melting of the intraliposomal doxorubicin-sulfate nanocrystals. The thermograms of Doxil and Lipodox are practically identical. The membrane phase transition is similar to that of drug-free nanoliposomes of the same size and lipid composition as Doxil, suggesting lack of significant drug-membrane interaction. The melting endotherm of the intraliposomal nanocrystals is 2.0-2.5-fold narrower than that of the crystals formed in a solution of 250mM ammonium sulfate and >60mg/ml doxorubicin. This suggests that nanovolume of liposomes improves doxorubicin-sulfate crystallinity. Moreover, both phase transitions are reversible in cycled DSC scanning (15-90-15°C). This indicates an unexpected "non-leaky" phospholipid phase transition and excellent physical and chemical stabilities of Doxil after short exposure to high temperature. Reducing mole% of cholesterol results in a "leaky" membrane phase transition of higher enthalpy. Namely, high mole% cholesterol is essential for the resistance to drug leakage during phase transition. Pegylated liposomal doxorubicin in which HSPC was replaced by DPPC shows the same non-leaky phase transition but at a lower temperature, indicating this type of phase transition is not unique to Doxil. The presence of DSPE-PEG2k increases the cooperativity of the phase transition. High-sensitivity DSC helps illuminate composition/structure/function relationships of Doxil, and is useful for the equivalence/similarity studies.

  9. Perfusion deconvolution in DSC-MRI with dispersion-compliant bases.

    PubMed

    Pizzolato, Marco; Boutelier, Timothé; Deriche, Rachid

    2017-02-01

    Perfusion imaging of the brain via Dynamic Susceptibility Contrast MRI (DSC-MRI) allows tissue perfusion characterization by recovering the tissue impulse response function and scalar parameters such as the cerebral blood flow (CBF), blood volume (CBV), and mean transit time (MTT). However, the presence of bolus dispersion causes the data to reflect macrovascular properties, in addition to tissue perfusion. In this case, when performing deconvolution of the measured arterial and tissue concentration time-curves it is only possible to recover the effective, i.e. dispersed, response function and parameters. We introduce Dispersion-Compliant Bases (DCB) to represent the response function in the presence and absence of dispersion. We perform in silico and in vivo experiments, and show that DCB deconvolution outperforms oSVD and the state-of-the-art CPI+VTF techniques in the estimation of effective perfusion parameters, regardless of the presence and amount of dispersion. We also show that DCB deconvolution can be used as a pre-processing step to improve the estimation of dispersion-free parameters computed with CPI+VTF, which employs a model of the vascular transport function to characterize dispersion. Indeed, in silico results show a reduction of relative errors up to 50% for dispersion-free CBF and MTT. Moreover, the DCB method recovers effective response functions that comply with healthy and pathological scenarios, and offers the advantage of making no assumptions about the presence, amount, and nature of dispersion.

  10. TG/DSC-FTIR and Py-GC investigation on pyrolysis characteristics of petrochemical wastewater sludge.

    PubMed

    Chen, Jianbiao; Mu, Lin; Jiang, Bo; Yin, Hongchao; Song, Xigeng; Li, Aimin

    2015-09-01

    The pyrolysis characteristics of petrochemical wastewater sludge (PS) were evaluated using TG/DSC-FTIR and fixed-bed reactor with GC. TGA experiments indicated that the pyrolysis of PS proceeded in three phases, and the thermographs shifted to higher temperatures with increasing heating rate. Chars FTIR showed that the absorption of O-H, C-H, C=O and C-C decreased with pyrolysis temperatures increasing. Gases FTIR correspondingly showed that H2O, CO, and CH4 generated at higher temperatures. For the fixed-bed reactor tests, H2 and CO were relatively higher in the pyrolysis gases, and CH4 was negligible at 436K. The kinetic triplets of PS pyrolysis were estimated by Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose, and integral master-plots method. The results suggested that the most potential kinetic models for the first and second phase were the order reaction model, while the random nucleation and nuclei growth model for the third phase.

  11. Effects of pH and buffer concentration on the thermal stability of etanercept using DSC and DLS.

    PubMed

    Kim, Nam Ah; An, In Bok; Lim, Dae Gon; Lim, Jun Yeul; Lee, Sang Yeol; Shim, Woo Sun; Kang, Nae-Gyu; Jeong, Seong Hoon

    2014-01-01

    The protein size, electrical interaction, and conformational stability of etanercept (marketed as Enbrel®) were examined by thermodynamic and light scattering methods with changing pH and buffer concentration. As pH of etanercept increased from pH 6.6 to 8.6, electrical repulsion in the solution increased, inducing a decrease in protein size. However, the size changed less in high buffer concentration and irreversible aggregation issues were not observed; in contrast, aggregates of about 1000 nm were observed in low buffer concentration at the pH range. Three significant unfolding transitions (Tm) were observed by differential scanning calorimetry (DSC). Unlikely to Tm1, Tm2 and Tm3 were increased as the pH increased. Higher Tm at high buffer concentration was observed, indicating increased conformational stability. The apparent activation energy of unfolding was further investigated since continuous increase of Tm2 and Tm3 was not sufficient to determine optimal conditions. A higher energy barrier was calculated at Tm2 than at Tm3. In addition, the energy barriers were the highest at pH from 7.4 to 7.8 where higher Tm1 was also observed. Therefore, the conformational stability of protein solution significantly changed with pH dependent steric repulsion of neighboring protein molecules. An optimized pH range was obtained that satisfied the stability of all three domains. Electrostatic circumstances and structural interactions resulted in irreversible aggregation at low buffer concentrations and were suppressed by increasing the concentration. Therefore, increased buffer concentration is recommended during protein formulation development, even in the earlier stages of investigation, to avoid protein instability issues.

  12. 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.

  13. 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.

  14. Comparative study of DSC-PWI and 3D-ASL in ischemic stroke patients.

    PubMed

    Zhang, Shui-xia; Yao, Yi-hao; Zhang, Shun; Zhu, Wen-jie; Tang, Xiang-yu; Qin, Yuan-yuan; Zhao, Ling-yun; Liu, Cheng-xia; Zhu, Wen-zhen

    2015-12-01

    The purpose of this study was to quantitatively analyze the relationship between three dimensional arterial spin labeling (3D-ASL) and dynamic susceptibility contrast-enhanced perfusion weighted imaging (DSC-PWI) in ischemic stroke patients. Thirty patients with ischemic stroke were included in this study. All subjects underwent routine magnetic resonance imaging scanning, diffusion weighted imaging (DWI), magnetic resonance angiography (MRA), 3D-ASL and DSC-PWI on a 3.0T MR scanner. Regions of interest (ROIs) were drawn on the cerebral blood flow (CBF) maps (derived from ASL) and multi-parametric DSC perfusion maps, and then, the absolute and relative values of ASL-CBF, DSC-derived CBF, and DSC-derived mean transit time (MTT) were calculated. The relationships between ASL and DSC parameters were analyzed using Pearson's correlation analysis. Receiver operative characteristic (ROC) curves were performed to define the thresholds of relative value of ASL-CBF (rASL) that could best predict DSC-CBF reduction and MTT prolongation. Relative ASL better correlated with CBF and MTT in the anterior circulation with the Pearson correlation coefficients (R) values being 0.611 (P<0.001) and-0.610 (P<0.001) respectively. ROC curves demonstrated that when rASL ≤0.585, the sensitivity, specificity and accuracy for predicting ROIs with rCBF<0.9 were 92.3%, 63.6% and 76.6% respectively. When rASL ≤0.952, the sensitivity, specificity and accuracy for predicting ROIs rMTT>1.0 were 75.7%, 89.2% and 87.8% respectively. ASL-CBF map has better linear correlations with DSC-derived parameters (DSC-CBF and MTT) in anterior circulation in ischemic stroke patients. Additionally, when rASL is lower than 0.585, it could predict DSC-CBF decrease with moderate accuracy. If rASL values range from 0.585 to 0.952, we just speculate the prolonged MTT.

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

    NASA Astrophysics Data System (ADS)

    Wang, Yifang

    2011-03-01

    The International Conferences on Calorimetry in High Energy Physics (also known as the Calor Conference series, started in October 1990 at Fermilab) address all aspects of calorimetric particle detection and measurement, with an emphasis on high energy physics experiments. The XIV International Conference on Calorimetry in High Energy Physics (Calor 2010) was held at the campus of the Institute of High Energy Physics, Beijing, China, from May 10-14, 2010. This conference brought together more than 110 participants from 20 countries, including senior scientists and young physicists. During the five days of the conference, 98 presentations were given in seven plenary sessions. The attendees had in-depth discussions on the latest developments and innovations in calorimetry, including the exciting new LHC results. From the presentations, 83 papers were published in this proceedings. The success of the conference was due to the participants' enthusiasm and the excellent talks given by the speakers, and to the conveners for organizing the individual sessions. We would like to thank the International Advisory Committee for giving us the opportunity to host this Conference in Beijing. Finally we would like to thank all the people involved in the organization of the Conference, who have provided valuable local support. Yifang WangChair of Local Organizing Committee International Advisory Committee M DanilovITEP Moscow M DiemozINFN Roma I A EreditatoBern F L FabbriINFN Frascati T KobayashiICEPP Tokyo M LivanPavia University & INFN P LubranoINFN Perugia S MagillANL Argonne A MaioLIPP Lisbon H OberlackMPI Munich A ParaFermilab R WigmansTTU Lubbock R YoshidaANL Argonne R ZhuCaltech Local Organizing Committee Y WangIHEP (Chair) Y GaoTshinghua University T HuIHEP (Scientific secretary) C LiUSTC W LiIHEP J LuIHEP P WangIHEP T XuIHEP L ZhouIHEP Session Conveners 1) Materials and detectors - Junguang Lu (IHEP), Francesca Nessi (CERN) 2) Algorithm and simulation - Nural Akchurin

  16. Endoplasmic Reticulum Exit of Golgi-resident Defective for SREBP Cleavage (Dsc) E3 Ligase Complex Requires Its Activity.

    PubMed

    Raychaudhuri, Sumana; Espenshade, Peter J

    2015-06-05

    Layers of quality control ensure proper protein folding and complex formation prior to exit from the endoplasmic reticulum. The fission yeast Dsc E3 ligase is a Golgi-localized complex required for sterol regulatory element-binding protein (SREBP) transcription factor activation that shows architectural similarity to endoplasmic reticulum-associated degradation E3 ligases. The Dsc E3 ligase consists of five integral membrane proteins (Dsc1-Dsc5) and functionally interacts with the conserved AAA-ATPase Cdc48. Utilizing an in vitro ubiquitination assay, we demonstrated that Dsc1 has ubiquitin E3 ligase activity that requires the E2 ubiquitin-conjugating enzyme Ubc4. Mutations that specifically block Dsc1-Ubc4 interaction prevent SREBP cleavage, indicating that SREBP activation requires Dsc E3 ligase activity. Surprisingly, Golgi localization of the Dsc E3 ligase complex also requires Dsc1 E3 ligase activity. Analysis of Dsc E3 ligase complex formation, glycosylation, and localization indicated that Dsc1 E3 ligase activity is specifically required for endoplasmic reticulum exit of the complex. These results define enzyme activity-dependent sorting as an autoregulatory mechanism for protein trafficking.

  17. Pulse calorimetry with a light bulb

    NASA Astrophysics Data System (ADS)

    Kraftmakher, Yaakov

    2004-11-01

    A normal light bulb provides excellent opportunities for learning modern calorimetric techniques. The tungsten filament in a light bulb allows calorimetric measurements to be made over a wide range of high temperatures. The filament serves simultaneously as a sample, a heater and a thermometer. A student experiment employing a pulse calorimetric technique is described. A brief review of existing calorimetric techniques is given, and the temperature dependence of specific heat of solids is considered.

  18. 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.

  19. 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.

  20. The retrogradation properties of glutinous rice and buckwheat starches as observed with FT-IR, 13C NMR and DSC.

    PubMed

    Lian, Xijun; Wang, Changjun; Zhang, Kunsheng; Li, Lin

    2014-03-01

    The experiment was conducted to study the retrogradation properties of glutinous rice and buckwheat starch with wavelengths of maximum absorbance, FT-IR, (13)C NMR, and DSC. The results show that the starches in retrograded glutinous rice starch and glutinous rice amylopectin could not form double helix. The IR results show that protein inhabits in glutinous rice and maize starches in a different way and appearance of C-H symmetric stretching vibration at 2852 cm(-1) in starch might be appearance of protein. Retrogradation untied the protein in glutinous amylopectin. Enthalpies of sweet potato and maize granules are higher than those of their retrograded starches. The (13)C NMR results show that retrogradation of those two starches leads to presence of β-anomers and retrogradation might decompose lipids in glutinous rice amylopectin into small molecules. Glutinous rice starch was more inclined to retrogradation than buckwheat starch. The DSC results show that the second peak temperatures for retrograded glutinous rice and buckwheat starches should be assigned to protein. The SEM results show that an obvious layer structure exists in retrograded glutinous rice amylopectin.

  1. 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.

  2. DSC: software tool for simulation-based design of control strategies applied to wastewater treatment plants.

    PubMed

    Ruano, M V; Ribes, J; Seco, A; Ferrer, J

    2011-01-01

    This paper presents a computer tool called DSC (Simulation based Controllers Design) that enables an easy design of control systems and strategies applied to wastewater treatment plants. Although the control systems are developed and evaluated by simulation, this tool aims to facilitate the direct implementation of the designed control system to the PC of the full-scale WWTP (wastewater treatment plants). The designed control system can be programmed in a dedicated control application and can be connected to either the simulation software or the SCADA of the plant. To this end, the developed DSC incorporates an OPC server (OLE for process control) which facilitates an open-standard communication protocol for different industrial process applications. The potential capabilities of the DSC tool are illustrated through the example of a full-scale application. An aeration control system applied to a nutrient removing WWTP was designed, tuned and evaluated with the DSC tool before its implementation in the full scale plant. The control parameters obtained by simulation were suitable for the full scale plant with only few modifications to improve the control performance. With the DSC tool, the control systems performance can be easily evaluated by simulation. Once developed and tuned by simulation, the control systems can be directly applied to the full-scale WWTP.

  3. Calorimetry measurements in less than 20 minutes

    SciTech Connect

    Perry, R.B. ); Cremers, T. )

    1991-01-01

    Argonne National Laboratory has developed a new series of 10 watt Bulk Plutonium Assay Calorimeters (BPAC10). The calorimeter measures bulk samples of plutonium bearing material in containers up to 5in. in diameter and 7in. high. The average measurement time is 19.7 minutes compared to 2--9 hours for the same sample measured in a water bath calorimeter. Measurement precision in the range of 1--10 watts is 1% to 0.1% and it is 0.010 watt for sample power less than 1 watt. BPAC10 series calorimeters are in use in two plutonium facilities at the EG G Rocky Flats Plant and at the Los Alamos National Laboratory TA55 Plutonium Facility. The paper presents a description of the calorimeter, discusses operating experience at Los Alamos, and presents a comparison of data on typical samples measured with both types of calorimeters. 5 refs., 5 figs., 1 tab.

  4. 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.

  5. 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…

  6. 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.

  7. 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…

  8. 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

  9. New detecting techniques for a future calorimetry

    NASA Astrophysics Data System (ADS)

    Auffray, E.; Buganov, O.; Fedorov, A.; Korjik, M.; Lecoq, P.; Tamulaitis, G.; Tikhomirov, S.; Vasil'ev, A.

    2015-02-01

    In the last forty years, application of crystalline materials in homogeneous Electromagnetic Calorimeters has played a crucial role in the discovery of matter properties and promoted a continuous progress in the detecting technique. The detection systems progressed from small detectors based on NaI(Tl), CsI(Na), BaF2, PbF2, and Bi4Ge3O12 to giant Electromagnetic Calorimeters of CMS, ALICE Collaborations at LHC and PANDA Collaboration at FAIR, where the systems consisted of thousands lead tungstate PbWO4 scintillation crystals. Lead tungstate (PWO) became the most extensively used scintillation material in high energy physics experiments. PWO possesses a unique combination of scintillation properties including high energy and time resolutions in the detection of high energy particles. Here, we report on the results of the two photon absorption in PWO crystals obtained by pump-probe technique using ultra short laser pulses. The results demonstrate that the relaxation processes in PWO offer capability of this material to be used in detection systems to make a time stamp with precision close to 10-12 s or even better.

  10. Characterization of pegylated liposomal mitomycin C lipid-based prodrug (Promitil®) by high sensitivity differential scanning calorimetry and cryogenic transmission electron microscopy.

    PubMed

    Wei, Xiaohui; Patil, Yogita; Ohana, Patricia; Amitay, Yasmine; Shmeeda, Hilary; Gabizon, Alberto; Barenholz, Yechezkel

    2017-01-03

    The effect of a lipidated prodrug of mitomycin C (MLP) on the membrane of a pegylated liposome formulation (PL-MLP), also known as Promitil®, was characterized through high-sensitivity differential scanning calorimetry (DSC), and cryo-TEM. The thermodynamic analysis demonstrated that MLP led to the formation of heterogeneous domains in the membrane plane of PL-MLP. MLP concentrated in prodrug-rich domains, arranged in high-ordered crystal-like structures, as suggested by the sharp and high enthalpy endotherm in the 1st heating scanning. After thiolytic cleavage of mitomycin C from MLP by dithiotreitol (DTT) treatment, the crystal-like prodrug domain disappears and a homogeneous membrane with stronger lipid interactions and higher phase transition temperature compared with the blank (MLP-free) liposomes is observed by DSC. In parallel, the rod-like discoid liposomes and the "kissing liposomes" seen by cryo-TEM in the PL-MLP formulation disappear, and liposome mean size and polydispersity increase after DTT treatment. Both MLP and the residual post-cleavage lipophilic moiety of the prodrug increased rigidity of the liposome membrane as indicated by DSC. These results confirm that MLP is inserted in the PL-MLP liposome membrane via its lipophilic anchor, and its mitomycin C moiety located mainly at the region of the phospholipid glycerol backbone and polar head-group. We hypothesize that Π-Π stacking between the planar aromatic rings of the mitomycin C moieties leads to the formation of prodrug-rich domains with highly ordered structure on the PL-MLP liposome membrane. This thermodynamically stable conformation may explain the high stability of the PL-MLP formulation. These results also provide us with an interesting example of the application of high sensitivity DSC in understanding the composition-structure-behavior dynamics of liposomal nanocarriers having a lipid-based drug as pharmaceutical ingredient.

  11. Simultaneous determination of the protein conversion process in porcine stratum corneum after pretreatment with skin enhancers by a combined microscopic FT-IR/DSC system

    NASA Astrophysics Data System (ADS)

    Lin, Shan-Yang; Duan, Kwo-Jen; Lin, Tsung-Chien

    1996-11-01

    A newly developed microscopic Fourier transform infrared (FT-IR) spectrometry combined with differential scanning calorimetry (DSC) has been used to investigate simultaneously the thermal response and IR spectral changes in protein structure in porcine stratum corneum (SC) after pretreatment with skin penetration enhancers (propylene glycol (PG), azone/PG, oleic acid (OA)/PG, vitamin C, and vitamin C+ OA/PG). The amide I and II bands of the protein were used as probes to determine its structural transformation with temperature. A reheating process was also performed. The dual effects of enhancer and temperature on the protein conformational changes of porcine SC were studied. The results indicate that the newly developed FT-IR/DSC system can continuously determine the thermoresponsive conversion process from α-helix to β-sheet in the keratin structure of porcine SC pretreated with different enhancers. The temperature-induced keratin conversion in the protein structure of porcine SC was irreversible, with or without pretreatment with skin penetration enhancers. The conformational transition in the protein during heating was found to be partially from the α-helix to a random coil structure, and partially from the α-helix to the β-sheet structure. The kinetics of this conversion for the first and second heating processes were significantly different; the conversion process for all the first-heated SC samples during the second heating process was slower than that of the samples during the first heating process. Moreover, it was found that the skin penetration enhancers were able to alter synergistically and promote keratin conversion in the protein structure of porcine SC when accompanying the heating process. PG, OA/PG and azone/PG were found to be the most effective.

  12. Comparative SAXS and DSC study on stratum corneum structural organization in an epidermal cell culture model (ROC): impact of cultivation time.

    PubMed

    Kuntsche, Judith; Herre, Angela; Fahr, Alfred; Funari, Sérgio S; Garidel, Patrick

    2013-12-18

    Cell cultured skin equivalents present an alternative for dermatological in vitro evaluations of drugs and excipients as they provide the advantage of availability, lower variability and higher assay robustness compared to native skin. For penetration/permeation studies, an adequate stratum corneum barrier similar to that of human stratum corneum is, however, a prerequisite. In this study, the stratum corneum lipid organization in an epidermal cell culture model based on rat epidermal keratinocytes (REK organotypic culture, ROC) was investigated by small-angle X-ray scattering (SAXS) in dependence on ROC cultivation time and in comparison to native human and rat stratum cornea. In addition, the thermal phase behavior was studied by differential scanning calorimetry (DSC) and barrier properties were checked by measurements of the permeability of tritiated water. The development of the barrier of ROC SC obtained at different cultivation times (7, 14 and 21 days at the air-liquid interface) was connected with an increase in structural order of the SC lipids in SAXS measurements: Already cultivation for 14 days at the air-liquid interface resulted overall in a competent SC permeability barrier and SC lipid organization. Cultivation for 21 days resulted in further minor changes in the structural organization of ROC SC. The SAXS patterns of ROC SC had overall large similarities with that of human SC and point to the presence of a long periodicity phase with a repeat distance of about 122Å, e.g. slightly smaller than that determined for human SC in the present study (127Å). Moreover, SAXS results also indicate the presence of covalently bound ceramides, which are crucial for a proper SC barrier, although the corresponding thermal transitions were not clearly detectable by DSC. Due to the competent SC barrier properties and high structural and organizational similarity to that of native human SC, ROC presents a promising alternative for in vitro studies, particularly as

  13. 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.

  14. Comparative kinetic analysis on thermal degradation of some cephalosporins using TG and DSC data

    PubMed Central

    2013-01-01

    Background The thermal decomposition of cephalexine, cefadroxil and cefoperazone under non-isothermal conditions using the TG, respectively DSC methods, was studied. In case of TG, a hyphenated technique, including EGA, was used. Results The kinetic analysis was performed using the TG and DSC data in air for the first step of cephalosporin’s decomposition at four heating rates. The both TG and DSC data were processed according to an appropriate strategy to the following kinetic methods: Kissinger-Akahira-Sunose, Friedman, and NPK, in order to obtain realistic kinetic parameters, even if the decomposition process is a complex one. The EGA data offer some valuable indications about a possible decomposition mechanism. The obtained data indicate a rather good agreement between the activation energy’s values obtained by different methods, whereas the EGA data and the chemical structures give a possible explanation of the observed differences on the thermal stability. A complete kinetic analysis needs a data processing strategy using two or more methods, but the kinetic methods must also be applied to the different types of experimental data (TG and DSC). Conclusion The simultaneous use of DSC and TG data for the kinetic analysis coupled with evolved gas analysis (EGA) provided us a more complete picture of the degradation of the three cephalosporins. It was possible to estimate kinetic parameters by using three different kinetic methods and this allowed us to compare the Ea values obtained from different experimental data, TG and DSC. The thermodegradation being a complex process, the both differential and integral methods based on the single step hypothesis are inadequate for obtaining believable kinetic parameters. Only the modified NPK method allowed an objective separation of the temperature, respective conversion influence on the reaction rate and in the same time to ascertain the existence of two simultaneous steps. PMID:23594763

  15. Using isothermal titration calorimetry to determine thermodynamic parameters of protein-glycosaminoglycan interactions.

    PubMed

    Dutta, Amit K; Rösgen, Jörg; Rajarathnam, Krishna

    2015-01-01

    It has now become increasingly clear that a complete atomic description of how biomacromolecules recognize each other requires knowledge not only of the structures of the complexes but also of how kinetics and thermodynamics drive the binding process. In particular, such knowledge is lacking for protein-glycosaminoglycan (GAG) complexes. Isothermal titration calorimetry (ITC) is the only technique that can provide various thermodynamic parameters-enthalpy, entropy, free energy (binding constant), and stoichiometry-from a single experiment. Here we describe different factors that must be taken into consideration in carrying out ITC titrations to obtain meaningful thermodynamic data of protein-GAG interactions.

  16. 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.

  17. Differential Scanning Calorimetry and Evolved Gas Analysis of Hydromagnesite

    NASA Technical Reports Server (NTRS)

    Lauer, H. V., Jr.; Golden, D. C.; Ming, Douglas W.; Boynton, W. V.

    1999-01-01

    Volatile-bearing minerals (e.g., Fe-oxyhydroxides, phyllosilicates, carbonates and sulfates) may be important phases on the surface of Mars. In order to characterize these phases the Thermal and Evolved Gas Analyzer (TEGA) flying on the Mars'98 lander will perform analyses on surface samples from Mars. Hydromagnesite [Mg5(CO3)4(OH)2.4H2O] is considered a good standard mineral to examine as a Mars soil analog component because it evolves both H2O and CO2 at temperatures between 0 and 600 C. Our aim here is to interpret the DSC signature of hydromagnesite under ambient pressure and 20 sccm N2 flow in the range 25 to 600 C. The DSC curve for hydromagnesite under the above conditions consists of three endothermic peaks at temperatures 296, 426, and 548 and one sharp exotherm at 511 C. X-ray analysis of the sample at different stop temperatures suggested that the exotherm corresponded with the formation of crystalline magnesite. The first endotherm was due to dehydration of hydromagnesite, and then the second one was due to the decomposition of carbonate, immediately followed by the formation of magnesite (exotherm) and its decomposition to periclase (last endotherm). Evolution of water and CO2 were consistent with the observed enthalpy changes. A library of such DSC-evolved gas curves for putative Martian minerals are currently being acquired in order to facilitate the interpretation of results obtained by a robotic lander.

  18. Multispectral image compression based on DSC combined with CCSDS-IDC.

    PubMed

    Li, Jin; Xing, Fei; Sun, Ting; You, Zheng

    2014-01-01

    Remote sensing multispectral image compression encoder requires low complexity, high robust, and high performance because it usually works on the satellite where the resources, such as power, memory, and processing capacity, are limited. For multispectral images, the compression algorithms based on 3D transform (like 3D DWT, 3D DCT) are too complex to be implemented in space mission. In this paper, we proposed a compression algorithm based on distributed source coding (DSC) combined with image data compression (IDC) approach recommended by CCSDS for multispectral images, which has low complexity, high robust, and high performance. First, each band is sparsely represented by DWT to obtain wavelet coefficients. Then, the wavelet coefficients are encoded by bit plane encoder (BPE). Finally, the BPE is merged to the DSC strategy of Slepian-Wolf (SW) based on QC-LDPC by deep coupling way to remove the residual redundancy between the adjacent bands. A series of multispectral images is used to test our algorithm. Experimental results show that the proposed DSC combined with the CCSDS-IDC (DSC-CCSDS)-based algorithm has better compression performance than the traditional compression approaches.

  19. Determining the main thermodynamic parameters of caffeine melting by means of DSC

    NASA Astrophysics Data System (ADS)

    Agafonova, E. V.; Moshchenskii, Yu. V.; Tkachenko, M. L.

    2012-06-01

    The temperature and enthalpy of the melting of caffeine, which are 235.5 ± 0.1°C and 19.6 ± 0.2 kJ/mol, respectively, are determined by DSC. The melting entropy and the cryoscopic constant of caffeine are calculated.

  20. Multispectral Image Compression Based on DSC Combined with CCSDS-IDC

    PubMed Central

    Li, Jin; Xing, Fei; Sun, Ting; You, Zheng

    2014-01-01

    Remote sensing multispectral image compression encoder requires low complexity, high robust, and high performance because it usually works on the satellite where the resources, such as power, memory, and processing capacity, are limited. For multispectral images, the compression algorithms based on 3D transform (like 3D DWT, 3D DCT) are too complex to be implemented in space mission. In this paper, we proposed a compression algorithm based on distributed source coding (DSC) combined with image data compression (IDC) approach recommended by CCSDS for multispectral images, which has low complexity, high robust, and high performance. First, each band is sparsely represented by DWT to obtain wavelet coefficients. Then, the wavelet coefficients are encoded by bit plane encoder (BPE). Finally, the BPE is merged to the DSC strategy of Slepian-Wolf (SW) based on QC-LDPC by deep coupling way to remove the residual redundancy between the adjacent bands. A series of multispectral images is used to test our algorithm. Experimental results show that the proposed DSC combined with the CCSDS-IDC (DSC-CCSDS)-based algorithm has better compression performance than the traditional compression approaches. PMID:25110741

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Crystallization kinetic of Sb-V2O5-TeO2 glasses investigated by DSC and their elastic moduli and Poisson's ratio

    NASA Astrophysics Data System (ADS)

    Souri, Dariush

    2015-01-01

    Ternary tellurate glasses of the form xSb-(60-x)V2O5-40TeO2 (0≤x≤15 in mol%) were prepared by using the usual melt quenching method. Differential scanning calorimetry (DSC) at different heating rates (φ) was used to thermal analyze and to gain more insight in to the thermal stability, glass forming tendency and so calorimetric behavior of the present glasses. The glass transition temperature (Tg), the temperature corresponding to the onset of crystallization (Tx) and also the crystallization temperature (TCr) were obtained at different heating rates, to estimate the key kinetic parameter of activation energy of crystallization (ΔE) by using different empirical formulas. Also some other thermal parameters such as thermal stability and glass forming tendency were determined. It was found that Tg, Tx and TCr increase with increase in Sb content and also with increase in heating rate. Moreover, Makishima-Makenzie's theory was employed to evaluate the Poisson's ratio and elastic moduli, indicating a strong relation between elastic properties and the structure of glass. From the mechanical and thermal data and also the values of oxygen molar volume ( V O *), it was founded that the glass systems can be divided in to "two compositional regions"; so, results indicate that glasses with 10≤x≤15 (especially for x=12) are more thermal stable and strong glasses, which make them as more useful and promising materials in technological advantages and device manufacturing.

  7. DSC and optical studies on BaO-Li2O-B2O3-CuO glass system

    NASA Astrophysics Data System (ADS)

    Bhogi, Ashok; Kumar, R. Vijaya; Ahmmad, Shaik Kareem; Kistaiah, P.

    2016-05-01

    Glasses with composition 15BaO-25Li2O-(60-x)B2O3 -xCuO (x= 0, 0.2, 0.4, 0.6, 0.8 and 1 mol%) were prepared by the conventional melt quenching technique. These glasses were characterized using X-ray diffraction (XRD), differential scanning calorimetry (DSC) and density measurements. Optical absorption studies were carried out as a function of copper ion concentration. The optical absorption spectra of studied glasses containing copper oxide exhibit a single broad band around 761nm which has been assigned to the 2B1g→2B2g transition. From these studies, the variations in the values of glass transition temperature (Tg) have been observed. The fundamental absorption edge has been determined from the optical absorption spectra. The values of optical band gap and Urbach energy were determined with increase in concentration of CuO. The variations in density, glass transition temperature, optical band gap and Urbach energy with CuO content have been discussed in terms of changes in the glass structure. The analysis of these results indicated that copper ions mostly exist in Cu2+ state in these glasses when the concentration of CuO ≤ 0.8 mol% and above this concentration copper ions seem to subsist in Cu1+ state.

  8. Distinct roles of the DmNav and DSC1 channels in the action of DDT and pyrethroids.

    PubMed

    Rinkevich, Frank D; Du, Yuzhe; Tolinski, Josh; Ueda, Atsushi; Wu, Chun-Fang; Zhorov, Boris S; Dong, Ke

    2015-03-01

    Voltage-gated sodium channels (Nav channels) are critical for electrical signaling in the nervous system and are the primary targets of the insecticides DDT and pyrethroids. In Drosophila melanogaster, besides the canonical Nav channel, Para (also called DmNav), there is a sodium channel-like cation channel called DSC1 (Drosophila sodium channel 1). Temperature-sensitive paralytic mutations in DmNav (para(ts)) confer resistance to DDT and pyrethroids, whereas DSC1 knockout flies exhibit enhanced sensitivity to pyrethroids. To further define the roles and interaction of DmNav and DSC1 channels in DDT and pyrethroid neurotoxicology, we generated a DmNav/DSC1 double mutant line by introducing a para(ts1) allele (carrying the I265N mutation) into a DSC1 knockout line. We confirmed that the I265N mutation reduced the sensitivity to two pyrethroids, permethrin and deltamethrin of a DmNav variant expressed in Xenopus oocytes. Computer modeling predicts that the I265N mutation confers pyrethroid resistance by allosterically altering the second pyrethroid receptor site on the DmNav channel. Furthermore, we found that I265N-mediated pyrethroid resistance in para(ts1) mutant flies was almost completely abolished in para(ts1);DSC1(-/-) double mutant flies. Unexpectedly, however, the DSC1 knockout flies were less sensitive to DDT, compared to the control flies (w(1118A)), and the para(ts1);DSC1(-/-) double mutant flies were even more resistant to DDT compared to the DSC1 knockout or para(ts1) mutant. Our findings revealed distinct roles of the DmNav and DSC1 channels in the neurotoxicology of DDT vs. pyrethroids and implicate the exciting possibility of using DSC1 channel blockers or modifiers in the management of pyrethroid resistance.

  9. Distinct Roles of the DmNav and DSC1 Channels in the Action of DDT and Pyrethroids

    PubMed Central

    Rinkevich, Frank D.; Du, Yuzhe; Tolinski, Josh; Ueda, Atsushi; Wu, Chun-Fang; Zhorov, Boris S.; Dong, Ke

    2015-01-01

    Voltage-gated sodium channels (Nav channels) are critical for electrical signaling in the nervous system and are the primary targets of the insecticides DDT and pyrethroids. In Drosophila melanogaster, besides the canonical Nav channel, Para (also called DmNav), there is a sodium channel-like cation channel called DSC1 (Drosophila sodium channel 1). Temperature-sensitive paralytic mutations in DmNav (parats) confer resistance to DDT and pyrethroids, whereas DSC1 knockout flies exhibit enhanced sensitivity to pyrethroids. To further define the roles and interaction of DmNav and DSC1 channels in DDT and pyrethroid neurotoxicology, we generated a DmNav/DSC1 double mutant line by introducing a parats1 allele (carrying the I265N mutation) into a DSC1 knockout line. We confirmed that the I265N mutation reduced the sensitivity to two pyrethroids, permethrin and deltamethrin of a DmNav variant expressed in Xenopus oocytes. Computer modeling predicts that the I265N mutation confers pyrethroid resistance by allosterically altering the second pyrethroid receptor site on the DmNav channel. Furthermore, we found that I265N-mediated pyrethroid resistance in parats1 mutant flies was almost completely abolished in parats1;DSC1−/− double mutant flies. Unexpectedly, however, the DSC1 knockout flies were less sensitive to DDT, compared to the control flies (w1118A), and the parats1;DSC1−/− double mutant flies were even more resistant to DDT compared to the DSC1 knockout or parats1 mutant. Our findings revealed distinct roles of the DmNav and DSC1 channels in the neurotoxicology of DDT vs. pyrethroids and implicate the exciting possibility of using DSC1 channel blockers or modifiers in the management of pyrethroid resistance. PMID:25687544

  10. Theoretical and experimental considerations on the enthalpic relaxation of organic glasses using differential scanning calorimetry.

    PubMed

    Mao, Chen; Chamarthy, Sai Prasanth; Byrn, Stephen R; Pinal, Rodolfo

    2010-01-14

    The enthalpy relaxation of amorphous salicin, used as model organic glass of pharmaceutical relevance, was investigated using a combination of DSC measurements and theoretical simulations. The combined approach makes it possible to discern between the effect of the glass forming properties of the material and the effects of the thermal history and experimental conditions. The approach also facilitates an unambiguous definition of the time scale of the experiment, such that objective comparison among relaxation time and glass transition temperature values can be made. The simulation provides accurate predictions of the DSC profiles obtained under a wide variety of experimental conditions. The effects of annealing time and the heating/cooling rate on the enthalpy recovery were explained by tracking the evolution of relaxation times as a function of temperature and time. The combined experimental and simulation approach also makes it possible to systematically explore the effect of specific glass forming properties, such as fragility and nonexponentiality, on the relaxation and associated thermal behavior of molecular organic glasses of pharmaceutical interest. To fully characterize these materials, it is necessary to go beyond the onset T(g) and include the early stages of the glass transition.

  11. 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.

  12. 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.

  13. 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.

  14. PREFACE: 16th International Conference on Calorimetry in High Energy Physics (CALOR 2014)

    NASA Astrophysics Data System (ADS)

    Novotny, Rainer W.

    2015-02-01

    The XVIth International Conference on Calorimetry in High Energy Physics - CALOR 2014 - was held in Giessen, Germany from 6-11 April 2014 at the Science Campus of the University. It was hosted by the Justus-Liebig-University and the HIC for FAIR Helmholtz International Center. The series of conferences on calorimetry were started in 1990 at Fermilab and are focusing primarily on operating and future calorimeter systems within the Hadron and High-Energy Physics community without neglecting the impact on other fields such as Astrophysics or Medical Imaging. Confirmed by the impressive list of over 70 oral presentations, 5 posters and over 100 attendees, the field of calorimetry appears alive and attractive. The present volume contains the written contributions of almost all presentations which can be found at http://calor2014.de. Time slots of 15 or 30 minutes including discussion were allocated. The conference was accompanied by a small exhibition of several industrial companies related to the field. The day before the opening of the scientific program, Richard Wigmans gave an excellent and vivid tutorial on basic aspects on calorimetry meant as an introduction for students and conference attendees new in the field. The opening ceremony was used to give an impression of the present and future status and the scientific program of the new FAIR facility nearby at Darmstadt presented by Klaus Peters from GSI. The conference program of the first day was dedicated to the performance and required future upgrade of the LHC experiments, dominated by ATLAS, CMS and LHCb. The program of the next day contained specific aspects on electronics and readout as well as calorimetry in outer space. Several contributions discussed in detail new concepts for hadron calorimeters within the CALICE collaboration completed by a session on sampling calorimeters. The next sections were dedicated to operating and future calorimeters at various laboratories and covering a wide range of

  15. Brain Metastases from Different Primary Carcinomas: an Evaluation of DSC MRI Measurements.

    PubMed

    Zhang, H; Zhang, G; Oudkerk, M

    2012-03-01

    This study evaluated the roles of different dynamic susceptibility contrast magnetic imaging (DSC MRI) measurements in discriminating between brain metastases derived from four common primary carcinomas. Thirty-seven patients with brain metastases were enrolled. Relative cerebral blood volume (rCBV), cerebral blood flow (rCBF) and relative mean transit time (rMTT) in both tumor and peritumoral edema were measured. Metastases were grouped by their primary tumor (lung, gastrointestinal, breast and renal cell carcinoma). DSC MRI measurements were compared between groups. Mean rCBV, rCBF, rMTT in tumor and peritumoral edema of all brain metastases (n=37) were 2.79 ± 1.73, 2.56 ± 2.11, 1.21 ± 0.48 and 1.05 ± 0.53, 0.86 ± 0.40, 1.99 ± 0.41, respectively. The tumoral rCBV (5.26 ± 1.89) and rCBF (5.32 ± 3.28) of renal metastases were greater than those of the other three metastases (P<0.05). The tumoral rMTT (1.58 ± 0.77) of breast metastases was statistically greater than that (0.96 ± 0.31) of gastrointestinal metastases (P=0.013). No statistical difference was found between peritumoral rCBV, rCBF and rMTT (P>0.05). Evaluating various DSC MRI measurements can provide complementary hemodynamic information on brain metastases. The tumoral rCBV, rCBF and likely rMTT can help discriminate between brain metastases originating from different primary carcinomas. The peritumoral DSC MRI measurements had limited value in discriminating between brain metastases.

  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. 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.

  18. Comparison of the Degree of Conversion of Resin Based Endodontic Sealers Using the DSC Technique

    PubMed Central

    Cotti, Elisabetta; Scungio, Paola; Dettori, Claudia; Ennas, Guido

    2011-01-01

    Objectives: The aim of this study was to determine the degree of conversion (DC) of three resin based endodontic sealers using the DSC technique. Methods: The sealers tested were: EndoREZ (ER) (Ultradent, South Jordan, UT); EndoREZ with Accelerator (ER+A) (Ultradent, South Jordan, UT); RealSeal (RS) (SybronEndo, Orange, CA). Two LED units were used to activate the sealers: UltraLume LED 5 (Ultradent, South Jordan, UT, USA); Mini LED Satelec (Satelec Acteon Group, Mérignac Cedex, France). Samples of 4.0 mg were analyzed with a DSC 7 calorimeter (Perkin Elmer Inc., Wellesley, MA, US). Each specimen was irradiated by each lamp four times for 20 seconds at an interval of 2 mins, while the DSC 7 recorded the heat flow developed during the treatment. The degree of conversion and the kinetic curves were calculated from the values of heat developed during each polymerization. The data were statistically analysed with a Kruskal-Wallis one-way ANOVA multiple range and Student-Newman-Keuls (SNK) tests at a P value of .05. Results: Statistically significant differences were found in the degree of conversion among the sealers: ER+A showed the highest values with both lamps. Conclusions: The higher polymerization rate in resin sealers is obtained with the addition of a catalyst. PMID:21494378

  19. Estimation of Temperature Range for Cryo Cutting of Frozen Mackerel using DSC

    NASA Astrophysics Data System (ADS)

    Okamoto, Kiyoshi; Hagura, Yoshio; Suzuki, Kanichi

    Frozen mackerel flesh was subjected to measurement of its fracture stress (bending energy) in a low temperature range. The optimum conditions for low temperature cutting, "cryo cutting," were estimated from the results of enthalpy changes measured by a differential scanning calorimeter (DSC). There were two enthalpy changes for gross transition on the DSC chart for mackerel, one was at -63°C to -77°C and the other at -96°C to -112°C. Thus we estimated that mackerel was able to cut by bending below -63°C and that there would be a great decrease in bending energy occurring at around -77°C and -112°C. In testing, there were indeed two great decreases of bending energy for the test pieces of mackerel that had been frozen at -40°C, one was at -70°C to -90°C and the other was at -100°C to -120°C. Therefore, the test pieces of mackerel could be cut by bending at -70°C. The results showed that the DSC measurement of mackerel flesh gave a good estimation of the appropriate cutting temperature of mackerel.

  20. Yeast sterol regulatory element-binding protein (SREBP) cleavage requires Cdc48 and Dsc5, a ubiquitin regulatory X domain-containing subunit of the Golgi Dsc E3 ligase.

    PubMed

    Stewart, Emerson V; Lloyd, S Julie-Ann; Burg, John S; Nwosu, Christine C; Lintner, Robert E; Daza, Riza; Russ, Carsten; Ponchner, Karen; Nusbaum, Chad; Espenshade, Peter J

    2012-01-02

    Schizosaccharomyces pombe Sre1 is a membrane-bound transcription factor that controls adaptation to hypoxia. Like its mammalian homolog, sterol regulatory element-binding protein (SREBP), Sre1 activation requires release from the membrane. However, in fission yeast, this release occurs through a strikingly different mechanism that requires the Golgi Dsc E3 ubiquitin ligase complex and the proteasome. The mechanistic details of Sre1 cleavage, including the link between the Dsc E3 ligase complex and proteasome, are not well understood. Here, we present results of a genetic selection designed to identify additional components required for Sre1 cleavage. From the selection, we identified two new components of the fission yeast SREBP pathway: Dsc5 and Cdc48. The AAA (ATPase associated with diverse cellular activities) ATPase Cdc48 and Dsc5, a ubiquitin regulatory X domain-containing protein, interact with known Dsc complex components and are required for SREBP cleavage. These findings provide a mechanistic link between the Dsc E3 ligase complex and the proteasome in SREBP cleavage and add to a growing list of similarities between the Dsc E3 ligase and membrane E3 ligases involved in endoplasmic reticulum-associated degradation.

  1. Subunit architecture of the Golgi Dsc E3 ligase required for sterol regulatory element-binding protein (SREBP) cleavage in fission yeast.

    PubMed

    Lloyd, S Julie-Ann; Raychaudhuri, Sumana; Espenshade, Peter J

    2013-07-19

    The membrane-bound sterol regulatory element-binding protein (SREBP) transcription factors regulate lipogenesis in mammalian cells and are activated through sequential cleavage by the Golgi-localized Site-1 and Site-2 proteases. The mechanism of fission yeast SREBP cleavage is less well defined and, in contrast, requires the Golgi-localized Dsc E3 ligase complex. The Dsc E3 ligase consists of five integral membrane subunits, Dsc1 through Dsc5, and resembles membrane E3 ligases that function in endoplasmic reticulum-associated degradation. Using immunoprecipitation assays and blue native electrophoresis, we determined the subunit architecture for the complex of Dsc1 through Dsc5, showing that the Dsc proteins form subcomplexes and display defined connectivity. Dsc2 is a rhomboid pseudoprotease family member homologous to mammalian UBAC2 and a central component of the Dsc E3 ligase. We identified conservation in the architecture of the Dsc E3 ligase and the multisubunit E3 ligase gp78 in mammals. Specifically, Dsc1-Dsc2-Dsc5 forms a complex resembling gp78-UBAC2-UBXD8. Further characterization of Dsc2 revealed that its C-terminal UBA domain can bind to ubiquitin chains but that the Dsc2 UBA domain is not essential for yeast SREBP cleavage. Based on the ability of rhomboid superfamily members to bind transmembrane proteins, we speculate that Dsc2 functions in SREBP recognition and binding. Homologs of Dsc1 through Dsc4 are required for SREBP cleavage and virulence in the human opportunistic pathogen Aspergillus fumigatus. Thus, these studies advance our organizational understanding of multisubunit E3 ligases involved in endoplasmic reticulum-associated degradation and fungal pathogenesis.

  2. Mechanistic investigation of the interaction between bisquaternary antimicrobial agents and phospholipids by liquid secondary ion mass spectrometry and differential scanning calorimetry.

    PubMed

    Pashynskaya, V A; Kosevich, M V; Gömöry, A; Vashchenko, O V; Lisetski, L N

    2002-01-01

    Mechanisms of interaction between the antimicrobial drugs decamethoxinum and aethonium, which are based on bisquaternary ammonium compounds, and a phospholipid component of biological membranes, dipalmitoylphosphatidylcholine, were studied by means of liquid secondary ion mass spectrometry (LSIMS) and differential scanning calorimetry (DSC). Supramolecular complexes of the drugs with this phospholipid were recorded under secondary ion mass spectrometric conditions. The dependence of the structures of these complexes on structural parameters of the dications of the bisquaternary ammonium compounds was demonstrated. Tandem mass spectrometric investigations of the metastable decay of doubly charged ions of decamethoxinum and aethonium complexes with dipalmitoylphosphatidylcholine allowed estimation of structural parameters of these complexes in the gas phase. Interactions of decamethoxinum and aethonium with model membrane assemblies built from hydrated dipalmitoylphosphatidylcholine were studied using DSC. It was shown that while both drugs can interact with model membranes, the mechanisms of such interactions for decamethoxinum and aethonium differ. The correlation between the nature of these interactions and structural and electronic parameters of the dications of the two bisquaternary agents is discussed. Interpretation of combined mass spectrometric and calorimetric experimental data led to proposals that the molecular mechanisms of antimicrobial action of bisquaternary ammonium compounds are related to their effect on the membrane phospholipid components of microbial cells.

  3. 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.

  4. 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.

  5. Rheological Behavior, Granule Size Distribution and Differential Scanning Calorimetry of Cross-Linked Banana (Musa paradisiaca) Starch.

    NASA Astrophysics Data System (ADS)

    Núñez-Santiago, María C.; Maristany-Cáceres, Amira J.; Suárez, Francisco J. García; Bello-Pérez, Arturo

    2008-07-01

    Rheological behavior at 60 °C, granule size distribution and Differential Scanning Calorimetry (DSC) tests were employed to study the effect of diverse reaction conditions: adipic acid concentration, pH and temperature during cross-linking of banana (Musa paradisiaca) starch. These properties were determined in native banana starch pastes for the purpose of comparison. Rheological behavior from pastes of cross-linked starch at 60 °C did not show hysteresis, probably due the cross-linkage of starch that avoided disruption of granules, elsewhere, native starch showed hysteresis in a thixotropic loop. All pastes exhibited non-Newtonian shear thinning behavior. In all cases, size distribution showed a decrease in the median diameter in cross-linked starches. This condition produces a decrease in swelling capacity of cross-linked starch. The median diameter decreased with an increase of acid adipic concentration; however, an increase of pH and Temperature produced an increase in this variable. Finally, an increase in gelatinization temperature and entalphy (ΔH) were observed as an effect of cross-linkage. An increase in acid adipic concentration produced an increase in Tonset and a decrease in ΔH. pH and temperature. The cross-linked of banana starch produced granules more resistant during the pasting procedure.

  6. Effect of polyglycerol esters additive on palm oil crystallization using focused beam reflectance measurement and differential scanning calorimetry.

    PubMed

    Saw, M H; Hishamuddin, E; Chong, C L; Yeoh, C B; Lim, W H

    2017-01-01

    The effect of 0.1-0.7% (w/w) of polyglycerol esters (PGEmix-8) on palm oil crystallization was studied using focused beam reflectance measurement (FBRM) to analyze the in-line changes of crystal size distribution during the crystallization. FBRM results show that 0.1-0.5% (w/w) of PGEmix-8 did not significantly affect nucleation but slightly retarded crystal growth. The use of 0.7% (w/w) additive showed greater heterogeneous nucleation compared to those with lower dosages of additive. Crystal growth was also greatly reduced when using 0.7% (w/w) dosage. The morphological study indicated that the palm oil crystals were smaller and more even in size than when more additive was added. Isothermal crystallization studies using differential scanning calorimetry (DSC) showed increased inhibitory effects on palm oil crystal growth with increasing concentration of PGEmix-8. These results imply that PGEmix-8 is a nucleation enhancing and crystal growth retarding additive in palm oil crystallization at 0.7% (w/w) dosage.

  7. 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.

  8. 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.

  9. Characterization of Gas Hydrates Formation and Dissociation Using Thermal Analysis and Calorimetry

    NASA Astrophysics Data System (ADS)

    Rudow, M.; Lilova, K.

    2015-12-01

    In general, the gas hydrates are formed at low temperature and high pressure which requires a special technique to mimic the natural conditions. The hydrate thermal properties: heat capacity, heat of dissociation, are crucial for evaluating the effects on climate change and for a prediction of the gas production rates from hydrate reservoirs. The effect of the porous materials on the dissociation of synthetic methane hydrates was investigated at 150 - 300 K and atmospheric pressure. Another experiment with methane hydrates, but at high pressure (20 MPa) was performed at near room temperature using a highly sensitive micro-differential scanning calorimeter with a specifically design high pressure vessel (the vessel can withstand a pressure up to 1000 bars). The thermal cycle for measuring the methane hydrate dissociation in water includes cooling down a water solution under a certain methane pressure (30 to 350 bars) to -30 C to allow water crystallization and hydrate formation, then heated up to room temperature. The endothermic peak, following the ice melting is associated to the hydrate dissociation process and gives the enthalpy of the hydrate decomposition. The kinetics of the hydrates formation could also be predicted by a rapid DSC cooling experiment followed by isothermal step and heating. Both dissociation and specific heats of synthetic methane and ethane hydrates were measured under high-pressure condition by using a heat-flow type calorimeter to understand thermodynamic properties of gas hydrates under submarine/sublacustrine environments. The large reserves of natural gas are present as clathrate hydrates in permafrost regions and beneath the oceans have generated interest in the study of their thermophysical properties such as heat capacity and thermal conductivity. The effect of isotopic substitution in both THF and water on the eutectic and hydrate melting temperatures in water-tetrahydrofuran systems studied by DSC will be shown as an example.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Use of thermal analysis techniques (TG-DSC) for the characterization of diverse organic municipal waste streams to predict biological stability prior to land application

    SciTech Connect

    Fernandez, Jose M.; Plaza, Cesar; Polo, Alfredo; Plante, Alain F.

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer Thermal analysis was used to assess stability and composition of organic matter in three diverse municipal waste streams. Black-Right-Pointing-Pointer Results were compared with C mineralization during 90-day incubation, FTIR and {sup 13}C NMR. Black-Right-Pointing-Pointer Thermal analysis reflected the differences between the organic wastes before and after the incubation. Black-Right-Pointing-Pointer The calculated energy density showed a strong correlation with cumulative respiration. Black-Right-Pointing-Pointer Conventional and thermal methods provide complimentary means of characterizing organic wastes. - Abstract: The use of organic municipal wastes as soil amendments is an increasing practice that can divert significant amounts of waste from landfill, and provides a potential source of nutrients and organic matter to ameliorate degraded soils. Due to the high heterogeneity of organic municipal waste streams, it is difficult to rapidly and cost-effectively establish their suitability as soil amendments using a single method. Thermal analysis has been proposed as an evolving technique to assess the stability and composition of the organic matter present in these wastes. In this study, three different organic municipal waste streams (i.e., a municipal waste compost (MC), a composted sewage sludge (CS) and a thermally dried sewage sludge (TS)) were characterized using conventional and thermal methods. The conventional methods used to test organic matter stability included laboratory incubation with measurement of respired C, and spectroscopic methods to characterize chemical composition. Carbon mineralization was measured during a 90-day incubation, and samples before and after incubation were analyzed by chemical (elemental analysis) and spectroscopic (infrared and nuclear magnetic resonance) methods. Results were compared with those obtained by thermogravimetry (TG) and differential scanning calorimetry (DSC

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Classification of tumor area using combined DCE and DSC MRI in patients with glioblastoma.

    PubMed

    Artzi, Moran; Blumenthal, Deborah T; Bokstein, Felix; Nadav, Guy; Liberman, Gilad; Aizenstein, Orna; Ben Bashat, Dafna

    2015-01-01

    This study proposes an automatic method for identification and quantification of different tissue components: the non-enhanced infiltrative tumor, vasogenic edema and enhanced tumor areas, at the subject level, in patients with glioblastoma (GB) based on dynamic contrast enhancement (DCE) and dynamic susceptibility contrast (DSC) MRI. Nineteen MR data sets, obtained from 12 patients with GB, were included. Seven patients were scanned before and 8 weeks following bevacizumab initiation. Segmentation of the tumor area was performed based on the temporal data of DCE and DSC at the group-level using k-means algorithm, and further at the subject-level using support vector machines algorithm. The obtained components were associated to different tissues types based on their temporal characteristics, calculated perfusion and permeability values and MR-spectroscopy. The method enabled the segmentation of the tumor area into the enhancing permeable component; the non-enhancing hypoperfused component, associated with vasogenic edema; and the non-enhancing hyperperfused component, associated with infiltrative tumor. Good agreement was obtained between the group-level, unsupervised and subject-level, supervised classification results, with significant correlation (r = 0.93, p < 0.001) and average symmetric root-mean-square surface distance of 2.5 ± 5.1 mm. Longitudinal changes in the volumes of the three components were assessed alongside therapy. Tumor area segmentation using DCE and DSC can be used to differentiate between vasogenic edema and infiltrative tumors in patients with GB, which is of major clinical importance in therapy response assessment.

  2. Crystallization and glass transition of the diols and aminoalcohols, according to DSC data

    NASA Astrophysics Data System (ADS)

    Solonina, I. A.; Rodnikova, M. N.; Kiselev, M. P.; Khoroshilov, A. V.

    2015-05-01

    Overcooling, crystallization, and glass transition of the diol series and aminoalcohols which are the liquids with spatial hydrogen-bond networks, which are the along with the overcooling of dioxane, dimethylsulfoxide, and acetonitrile, which do not have such networks were studied by DSC. The observed phenomena are explained by the stability of H-bond networks. It was concluded that changes in the stability of the networks in and between series of diols and aminoalcohols are due to differences between their molecular structures, the energies of their hydrogen bonds, and their network topologies.

  3. DSC method: Determination of amorphous fraction in solid dosage and fragility

    NASA Astrophysics Data System (ADS)

    Saini, Manoj K.

    2015-06-01

    We have used Differential Scanning Calorimeter (DSC) method to quantifying the amorphous content in solid dosage of a commonly used drugs namely mephenesin. The glass transition temperature (Tg) of supercooled liquid sample and melting temperature (Tm) of as received sample are found to be 232.2 K and 343.1 K respectively. The "fragility index" of mephenesin has been discussed in detail using the coupling model (m = 250(± 30) - 320βKWW) and compared with acetaminophen and methocarbamol. The sample studied here is found to be kinetically strong in comparison.

  4. 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

  5. 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''.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. A Serious Game for Massive Training and Assessment of French Soldiers Involved in Forward Combat Casualty Care (3D-SC1): Development and Deployment

    PubMed Central

    Mérat, Stéphane; Malgras, Brice; Petit, Ludovic; Queran, Xavier; Bay, Christian; Boutonnet, Mathieu; Jault, Patrick; Ausset, Sylvain; Auroy, Yves; Perez, Jean Paul; Tesnière, Antoine; Pons, François; Mignon, Alexandre

    2016-01-01

    Background The French Military Health Service has standardized its military prehospital care policy in a ‘‘Sauvetage au Combat’’ (SC) program (Forward Combat Casualty Care). A major part of the SC training program relies on simulations, which are challenging and costly when dealing with more than 80,000 soldiers. In 2014, the French Military Health Service decided to develop and deploy 3D-SC1, a serious game (SG) intended to train and assess soldiers managing the early steps of SC. Objectives The purpose of this paper is to describe the creation and production of 3D-SC1 and to present its deployment. Methods A group of 10 experts and the Paris Descartes University Medical Simulation Department spin-off, Medusims, coproduced 3D-SC1. Medusims are virtual medical experiences using 3D real-time videogame technology (creation of an environment and avatars in different scenarios) designed for educational purposes (training and assessment) to simulate medical situations. These virtual situations have been created based on real cases and tested on mannequins by experts. Trainees are asked to manage specific situations according to best practices recommended by SC, and receive a score and a personalized feedback regarding their performance. Results The scenario simulated in the SG is an attack on a patrol of 3 soldiers with an improvised explosive device explosion as a result of which one soldier dies, one soldier is slightly stunned, and the third soldier experiences a leg amputation and other injuries. This scenario was first tested with mannequins in military simulation centers, before being transformed into a virtual 3D real-time scenario using a multi-support, multi–operating system platform, Unity. Processes of gamification and scoring were applied, with 2 levels of difficulty. A personalized debriefing was integrated at the end of the simulations. The design and production of the SG took 9 months. The deployment, performed in 3 months, has reached 84 of 96

  14. Thermodynamic properties of aqueous PEO-PPO-PEO micelles with added methylparaben determined by differential scanning calorimetry.

    PubMed

    Thompson, Andre Lamont; Love, Brian James

    2013-05-15

    DSC experiments were performed on aqueous solutions of PEO-PPO-PEO (P105) amphiphiles in the low concentration regime (0-1%) to resolve the critical micelle concentration (cmc) both neat and co-formulated with methylparaben (MP). Further work was done at 10% amphiphilic copolymer concentrations and co-formulated with MP to resolve the variations in enthalpy. The compensation temperature, T(compensation), was determined from the analyses for neat P105 as 293.9 K; adding MP raises this to 328.43 K.

  15. An investigation into the release of cefuroxime axetil from taste-masked stearic acid microspheres. III. The use of DSC and HSDSC as means of characterising the interaction of the microspheres with buffered media.

    PubMed

    Robson, H; Craig, D Q; Deutsch, D

    2000-05-25

    Stearic acid coated cefuroxime axetil (SACA) microspheres have been studied using differential scanning calorimetry (DSC) and high sensitivity DSC (HSDSC) in order to examine the interaction between the spheres and a range of buffer systems, with a view to further enhance the understanding of the mechanism of drug release developed in earlier studies [Robson et al., 1999, 2000]. DSC studies indicated that after immersion in Sorensens modified phosphate buffer (SMPB) pH 5.9 followed by washing and drying, no change in the thermal properties of the spheres was detected up to 60 min of immersion, with a single endotherm noted at circa 56 degrees C, that corresponded to the melting of the stearic acid used in this study; similar results were obtained for systems immersed in distilled water. After immersion in SMPB pH 7.0 and 8.0, however, a second peak was noted at approximately 67 degrees C that increased in magnitude relative to the lower temperature endotherm with increasing exposure time to the medium. Spheres that had not been previously washed prior to drying showed complete conversion to the higher temperature endotherm for these two buffers. Systems which had been exposed to a range of pH 7.0 buffers (citrate-phosphate buffer (CPB), phosphate buffer mixed (PBM), boric acid buffer (BAB)) were then examined. Only the CPB systems showed evidence for conversion to the higher melting form. PBM systems to which further sodium had been added were then examined. A maximum conversion was found at 0.05 M sodium, which was in agreement with the maximum in release rate found in a previous study [Robson et al., 2000]. HSDSC was then used to examine systems that were immersed in the buffer. For SMPB, pH 5.9 and distilled water, only the endotherm corresponding to the stearic acid melting was seen. However, for SMPB pH 7.0 and 8.0, three peaks were seen, two corresponding to those seen for the DSC studies and a further lower temperature peak at circa 44 degrees C. Studies on

  16. Synthesis of dry AgPO3 glass and characterization by Raman, IR and m-DSC

    NASA Astrophysics Data System (ADS)

    Novita, D.; Boolchand, P.

    2008-03-01

    Glass transition temperature of titled glass apparently vary over a wide range, 163 C< Tg< 254 C depending on the humidity of the ambient environment in which precursors are handled^1. We have examined a set of 4 samples (1(181 C),2(203 C), 3(242.7 C), 4(254 C) with different Tgs indicated in parenthesis, in m-DSC, Raman and IR experiments to elucidate the role of bonded water. Our results show that the glass transition endotherm of sample 4 (dry) is characteristic of a stressed-rigid glass, while that of sample 1 (wet) of a flexible glass. Although Raman scattering of samples 1 and 4 look superficially similar, they are different in details; the Boson peak in sample 4 has a stronger intensity than in sample 1. IR reflectance signal strength in the mid-IR range is weaker for sample 4 than for sample 1, and furthermore differs in details. These results show that presence of water disrupts the P-O-P chain network by replacing bridging O with terminal OH^- ends. And once water is bonded, it is difficult to remove it completely. These results will be compared to previous reports in the field. ^1 D.I.Novita and P.Boolchand Phys. Rev. B (in press) * Supported by NSF grant DMR 04-56472

  17. Remote Evaluation of Rotational Velocity Using a Quadrant Photo-Detector and a DSC Algorithm

    PubMed Central

    Zeng, Xiangkai; Zhu, Zhixiong; Chen, Yang

    2016-01-01

    This paper presents an approach to remotely evaluate the rotational velocity of a measured object by using a quadrant photo-detector and a differential subtraction correlation (DSC) algorithm. The rotational velocity of a rotating object is determined by two temporal-delay numbers at the minima of two DSCs that are derived from the four output signals of the quadrant photo-detector, and the sign of the calculated rotational velocity directly represents the rotational direction. The DSC algorithm does not require any multiplication operations. Experimental calculations were performed to confirm the proposed evaluation method. The calculated rotational velocity, including its amplitude and direction, showed good agreement with the given one, which had an amplitude error of ~0.3%, and had over 1100 times the efficiency of the traditional cross-correlation method in the case of data number N > 4800. The confirmations have shown that the remote evaluation of rotational velocity can be done without any circular division disk, and that it has much fewer error sources, making it simple, accurate and effective for remotely evaluating rotational velocity. PMID:27120607

  18. Increased cortical capillary transit time heterogeneity in Alzheimer's disease: a DSC-MRI perfusion study.

    PubMed

    Eskildsen, Simon F; Gyldensted, Louise; Nagenthiraja, Kartheeban; Nielsen, Rune B; Hansen, Mikkel Bo; Dalby, Rikke B; Frandsen, Jesper; Rodell, Anders; Gyldensted, Carsten; Jespersen, Sune N; Lund, Torben E; Mouridsen, Kim; Brændgaard, Hans; Østergaard, Leif

    2017-02-01

    Alzheimer's disease (AD) is characterized by the accumulation of hyperphosphorylated tau and neurotoxic Aβ in the brain parenchyma. Hypoxia caused by microvascular changes and disturbed capillary flows could stimulate this build-up of AD-specific proteins in the brain. In this study, we compared cerebral microcirculation in a cohort of AD and mild cognitive impairment (MCI) patients with that of age-matched controls, all without a history of diabetes or of hypertension for more than 2 years, using dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI). Vascular flow disturbances were quantified using a parametric model and mapped to the mid-cortical surface for group-wise statistical analysis. We found widespread hypoperfusion in patients compared with controls and identified areas of increased relative capillary transit time heterogeneity (RTH), consistent with low tissue oxygen tension. Notably, RTH was positively correlated with white matter hyperintensities and positively correlated with symptom severity in the patient cohort. These correlations extended over large parts of the temporal, parietal, and frontal cortices. The results support the hypothesis of disturbed capillary flow patterns in AD and suggest that DSC-MRI may provide imaging biomarkers of impaired cerebral microcirculation in AD.

  19. Decentralized Adaptive Neural Output-Feedback DSC for Switched Large-Scale Nonlinear Systems.

    PubMed

    Long, Lijun; Zhao, Jun

    2016-03-08

    In this paper, for a class of switched large-scale uncertain nonlinear systems with unknown control coefficients and unmeasurable states, a switched-dynamic-surface-based decentralized adaptive neural output-feedback control approach is developed. The approach proposed extends the classical dynamic surface control (DSC) technique for nonswitched version to switched version by designing switched first-order filters, which overcomes the problem of multiple ``explosion of complexity.'' Also, a dual common coordinates transformation of all subsystems is exploited to avoid individual coordinate transformations for subsystems that are required when applying the backstepping recursive design scheme. Nussbaum-type functions are utilized to handle the unknown control coefficients, and a switched neural network observer is constructed to estimate the unmeasurable states. Combining with the average dwell time method and backstepping and the DSC technique, decentralized adaptive neural controllers of subsystems are explicitly designed. It is proved that the approach provided can guarantee the semiglobal uniformly ultimately boundedness for all the signals in the closed-loop system under a class of switching signals with average dwell time, and the tracking errors to a small neighborhood of the origin. A two inverted pendulums system is provided to demonstrate the effectiveness of the method proposed.

  20. Diffusion of liquid polystyrene into glassy poly(phenylene oxide) characterized by DSC

    NASA Astrophysics Data System (ADS)

    Li, Linling; Wang, Xiaoliang; Zhou, Dongshan; Xue, Gi

    2013-03-01

    We report a diffusion study on the polystyrene/poly(phenylene oxide) (PS/PPO) mixture consisted by the PS and PPO nanoparticles. Diffusion of liquid PS into glassy PPO (l-PS/g-PPO) is promoted by annealing the PS/PPO mixture at several temperatures below Tg of the PPO. By tracing the Tgs of the PS-rich domain behind the diffusion front using DSC, we get the relationships of PS weight fractions and diffusion front advances with the elapsed diffusion times at different diffusion temperatures using the Gordon-Taylor equation and core-shell model. We find that the plots of weight fraction of PS vs. elapsed diffusion times at different temperatures can be converted to a master curve by Time-Temperature superposition, and the shift factors obey the Arrhenius equation. Besides, the diffusion front advances of l-PS into g-PPO show an excellent agreement with the t1/2 scaling law at the beginning of the diffusion process, and the diffusion coefficients of different diffusion temperatures also obey the Arrhenius equation. We believe the diffusion mechanism for l-PS/g-PPO should be the Fickean law rather than the Case II, though there are departures of original linearity at longer diffusion times due to the limited liquid supply system. Diffusion of liquid polystyrene into glassy poly(phenylene oxide) characterized by DSC

  1. Remote Evaluation of Rotational Velocity Using a Quadrant Photo-Detector and a DSC Algorithm.

    PubMed

    Zeng, Xiangkai; Zhu, Zhixiong; Chen, Yang

    2016-04-25

    This paper presents an approach to remotely evaluate the rotational velocity of a measured object by using a quadrant photo-detector and a differential subtraction correlation (DSC) algorithm. The rotational velocity of a rotating object is determined by two temporal-delay numbers at the minima of two DSCs that are derived from the four output signals of the quadrant photo-detector, and the sign of the calculated rotational velocity directly represents the rotational direction. The DSC algorithm does not require any multiplication operations. Experimental calculations were performed to confirm the proposed evaluation method. The calculated rotational velocity, including its amplitude and direction, showed good agreement with the given one, which had an amplitude error of ~0.3%, and had over 1100 times the efficiency of the traditional cross-correlation method in the case of data number N > 4800. The confirmations have shown that the remote evaluation of rotational velocity can be done without any circular division disk, and that it has much fewer error sources, making it simple, accurate and effective for remotely evaluating rotational velocity.

  2. 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.

  3. Change in physical structure of a phenol-spiked sapric histosol observed by Differential Scanning Calorimetry

    NASA Astrophysics Data System (ADS)

    Ondruch, Pavel; Kucerik, Jiri; Schaumann, Gabriele E.

    2014-05-01

    Interactions of pollutants with soil organic matter (SOM), their fate and transformation are crucial for understanding of soil functions and properties. In past, many papers dealing with sorption of organic and inorganic compounds have been published. However, their aim was almost exceptionally fo-cused on the pollutants themselves, determination of sorption isotherms and influence of external factors, while the change in SOM supramolecular structure was usually ignored. The SOM structure is, however, very important, since the adsorbed pollutant might have a significant influence on soil stability and functions. Differential scanning calorimetry (DSC) represents a technique, which has been successfully used to analyze the physical structure and physico-chemical aging of SOM. It has been found out that water molecules progressively stabilize SOM (water molecule bridge (WaMB)) (Schaumann & Bertmer 2008). Those bridges connect and stabilize SOM and can be disrupted at higher temperature (WaMB transition; (Kunhi Mouvenchery et al. 2013; Schaumann et al. 2013). In the same temperature region melting of aliphatic moieties can be observed (Hu et al. 2000; Chilom & Rice 2005; Kucerik et al. submitted 2013). In this work, we studied the effect of phenol on the physical structure of sapric histosol. Phenol was dissolved in various solvents (water, acetone, hexane, methanol) and added to soils. After the evaporation of solvents by air drying, the sample was equilibrated at 76% relative humidity for 3 weeks. Using DSC, we investigated the influence of phenol on histosol structure and time dependence of melting temperature of aliphatic moieties and WaMB transition. While addition of pure organic solvent only resulted in slightly increased transition temperatures, both melting temperature and WaMB transition temperature were significantly reduced in most cases if phenol was dissolved in these solvents. Water treatment caused a decrease in WaMB transition temperature but

  4. 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.

  5. Phase-Change Characteristic Analysis of Partially Melted Sodium Acetate Trihydrate Using DSC

    NASA Astrophysics Data System (ADS)

    Jin, Xing; Medina, Mario A.; Zhang, Xiaosong; Zhang, Shuanglong

    2014-01-01

    Sodium acetate trihydrate (SAT), which is a kind of phase-change material, offers high potential for application in thermal energy storage. However, SAT has a natural tendency to supercool during its solidification process. Adding nucleating agents has been suggested as a possible solution. In this paper, the phase-change characteristics of the partially melted SAT were analyzed using a differential scanning calorimeter (DSC). A phenomenon related to SAT undergoing phase change was discovered and analyzed. The results showed that if SAT were cooled when it was partially melted, it would release heat and quickly solidify without adding any nucleating agents. Therefore, if the temperature range of SAT was controlled properly, supercooling could be significantly prevented.

  6. Thermooxidative stability of poppy seeds studied by non-isothermal DSC measurements.

    PubMed

    Cibulková, Zuzana; Čertík, Milan; Dubaj, Tibor

    2014-05-01

    Papaver somniferum L. is an important crop cultivated mostly for seed production. Poppy seeds have a high nutritive value and are used as a food and as a source of edible oil. This oil is a rich source of polyunsaturated fatty acids. It is well known that the unsaturated fatty acids easily undergo oxidation reactions, which lead to the reduction of shelf life, nutritional quality, development of unpleasant tastes and odors. The goal of this study was to develop the methodology for testing the stability of poppy seeds using non-isothermal DSC. For the treatment of the experimental data a method based on non-Arrhenian temperature function has been applied and the values the kinetic parameters have been obtained. In order to assess the durability of the commercial poppy seeds, the lengths of induction periods have been calculated.

  7. Comparison of dual-echo DSC-MRI- and DCE-MRI-derived contrast agent kinetic parameters.

    PubMed

    Quarles, C Chad; Gore, John C; Xu, Lei; Yankeelov, Thomas E

    2012-09-01

    The application of dynamic susceptibility contrast (DSC) MRI methods to assess brain tumors is often confounded by the extravasation of contrast agent (CA). Disruption of the blood-brain barrier allows CA to leak out of the vasculature leading to additional T(1), T(2) and T(2) relaxation effects in the extravascular space, thereby affecting the signal intensity time course in a complex manner. The goal of this study was to validate a dual-echo DSC-MRI approach that separates and quantifies the T(1) and T(2) contributions to the acquired signal and enables the estimation of the volume transfer constant, K(trans), and the volume fraction of the extravascular extracellular space, v(e). To test the validity of this approach, DSC-MRI- and dynamic contrast enhanced (DCE) MRI-derived K(trans) and v(e) estimates were spatially compared in both 9L and C6 rat brain tumor models. A high degree of correlation (concordance correlation coefficients >0.83, Pearson's r>0.84) and agreement was found between the DSC-MRI- and DCE-MRI-derived measurements. These results indicate that dual-echo DSC-MRI can be used to simultaneously extract reliable DCE-MRI kinetic parameters in brain tumors in addition to conventional blood volume and blood flow metrics.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  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. An evaluation of the transition temperature range of super-elastic orthodontic NiTi springs using differential scanning calorimetry.

    PubMed

    Barwart, O; Rollinger, J M; Burger, A

    1999-10-01

    Differential scanning calorimetry (DSC) was used to determine the transition temperature ranges (TTR) of four types of super-elastic orthodontic nickel-titanium coil springs (Sentalloy). A knowledge of the TTR provides information on the temperature at which a NiTi wire or spring can assume superelastic properties and when this quality disappears. The spring types in this study can be distinguished from each other by their characteristic TTR during cooling and heating. For each tested spring type a characteristic TTR during heating (austenite transformation) and cooling (martensite transformation) was evaluated. The hysteresis of the transition temperature, found between cooling and heating, was 3.4-5.2 K. Depending on the spring type the austenite transformation started (As) at 9.7-17.1 degrees C and finished (Af) at 29.2-37 degrees C. The martensite transformation starting temperature (Ms) was evaluated at 32.6-25.4 degrees C, while Mf (martensite transformation finishing temperature) was 12.7-6.5 degrees C. The results show that the springs become super-elastic when the temperature increases and As is reached. They undergo a loss of super-elastic properties and a rapid decrease in force delivery when they are cooled to Mf. For the tested springs, Mf and As were found to be below room temperature. Thus, at room temperature and some degrees lower, all the tested springs exert super-elastic properties. For orthodontic treatment this means the maintenance of super-elastic behaviour, even when mouth temperature decreases to about room temperature as can occur, for example, during meals.

  1. Antiferroelectric liquid crystals studied by DSC, electro-optic, and dielectric methods

    NASA Astrophysics Data System (ADS)

    Marzec, M.; Fafara, A.; Wrobel, S.; Godlewska, Malgorzata; Dabrowski, Roman S.; Czuprynski, Krzysztof L.; Haase, Wolfgang

    2000-05-01

    Thermal properties of four liquid crystalline substances exhibiting antiferroelectric SmCA* and ferroelectric SmC* phases were studied using differential scanning calorimetry, texture observation, electrooptic measurements and dielectric spectroscopy. The measurements were performed both on heating and cooling of the samples. All four substances studied in this work are characterized by a complex polymorphism. The temperatures of phase transitions and enthalpy changes associated with them were determined. The transition from the liquid crystalline to the crystalline state showed significant hysteresis for all four substances studied. Textures observations and electrooptic measurements were performed using ITO cells having thickness from 6 to 10 micrometers . The measurements of spontaneous polarization were performed by means of reversal current method. Spontaneous polarization was measured for a few frequencies of the triangular voltage applied. Temperature dependencies of spontaneous polarization have been studied as a function of the side chain structure.

  2. Localization and interaction of hydroxyflavones with lipid bilayer model membranes: a study using DSC and multinuclear NMR.

    PubMed

    Sinha, Ragini; Joshi, Akshada; Joshi, Urmila J; Srivastava, Sudha; Govil, Girjesh

    2014-06-10

    The localization and interaction of six naturally occurring flavones (FLV, 5HF, 6HF, 7HF, CHY and BLN) in DPPC bilayers were studied using DSC and multi-nuclear NMR. DSC results indicate that FLV and 6HF interact with alkyl chains. The (1)H NMR shows interaction of flavones with the sn-glycero region. Ring current induced chemical shifts indicate that 6HF and BLN acquire parallel orientation in bilayers. 2D NOESY spectra indicate partitioning of the B-ring into the alkyl chain region. The DSC, NMR and binding studies indicate that 5HF and 7HF are located near head group region, while 6HF, CHY and BLN are located in the vicinity of sn-glycero region, and FLV is inserted deepest in the membrane.

  3. 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.

  4. 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.

  5. 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.

  6. The Thermal Conductivity Measurements of Solid Samples by Heat Flux Differantial Scanning Calorimetry

    NASA Astrophysics Data System (ADS)

    Kök, M.; Aydoǧdu, Y.

    2007-04-01

    The thermal conductivity of polyvinylchloride (PVC), polysytrene (PS) and polypropylene (PP) were measured by heat flux DSC. Our results are in good agreement with the results observed by different methods.

  7. Continuous gradient temperature Raman spectroscopy and differential scanning calorimetry of N-3DPA and DHA from -100 to 10°C.

    PubMed

    Broadhurst, C Leigh; Schmidt, Walter F; Nguyen, Julie K; Qin, Jianwei; Chao, Kuanglin; Aubuchon, Steven R; Kim, Moon S

    2017-03-22

    Docosahexaenoic acid (DHA, 22:6n-3) is exclusively utilized in fast signal processing tissues such as retinal, neural and cardiac. N-3 docosapentaenoic acid (n-3DPA, 22:5n-3), with just one less double bond, is also found in the marine food chain yet cannot substitute for DHA. Gradient temperature Raman spectroscopy (GTRS) applies the temperature gradients utilized in differential scanning calorimetry (DSC) to Raman spectroscopy, providing a straightforward technique to identify molecular rearrangements that occur near and at phase transitions. Herein we apply GTRS and both conventional and modulated DSC to n-3DPA and DHA from -100 to 20°C. Three-dimensional data arrays with 0.2°C increments and first derivatives allowed complete assignment of solid, liquid and transition state vibrational modes. Melting temperatures n-3DPA (-45°C) and DHA (-46°C) are similar and show evidence for solid-state phase transitions not seen in n-6DPA (-27°C melt). The C6H2 site is an elastic marker for temperature perturbation of all three lipids, each of which has a distinct three dimensional structure. N-3 DPA shows the spectroscopic signature of saturated fatty acids from C1 to C6. DHA does not have three aliphatic carbons in sequence; n-6DPA does but they occur at the methyl end, and do not yield the characteristic signal. DHA appears to have uniform twisting from C6H2 to C12H2 to C18H2 whereas n-6DPA bends from C12 to C18, centered at C15H2. For n-3DPA, twisting is centered at C6H2 adjacent to the C2-C3-C4-C5 aliphatic moiety. These molecular sites are the most elastic in the solid phase and during premelting.

  8. Comparison of thermal effects of stilbenoid analogs in lipid bilayers using differential scanning calorimetry and molecular dynamics: correlation of thermal effects and topographical position with antioxidant activity.

    PubMed

    Koukoulitsa, Catherine; Durdagi, Serdar; Siapi, Eleni; Villalonga-Barber, Carolina; Alexi, Xanthippi; Steele, Barry R; Micha-Screttas, Maria; Alexis, Michael N; Tsantili-Kakoulidou, Anna; Mavromoustakos, Thomas

    2011-07-01

    In previous studies it was shown that cannabinoids (CBs) bearing a phenolic hydroxyl group modify the thermal properties of lipid bilayers more significantly than methylated congeners. These distinct differential properties were attributed to the fact that phenolic hydroxyl groups constitute an anchoring group in the vicinity of the head-group, while the methylated analogs are embedded deeper towards the hydrophobic region of the lipid bilayers. In this work the thermal effects of synthetic polyphenolic stilbenoid analogs and their methylated congeners have been studied using differential scanning calorimetry (DSC). Molecular dynamics (MD) simulations have been performed to explain the DSC results. Thus, two of their phenolic hydroxyl groups orient in the lipid bilayers in such a way that they anchor in the region of the head-group. In contrast, their methoxy congeners cannot anchor effectively and are embedded deeper in the hydrophobic segment of the lipid bilayers. The MD results explain the fact that hydroxystilbenoid analogs exert more significant effects on the pretransition than their methoxy congeners, especially at low concentrations. To maximize the polar interactions, the two phenolic hydroxyl groups are localized in the vicinity of the head-group region, directing the remaining hydroxy group in the hydrophobic region. This topographical position of stilbenoid analogs forms a mismatch that explains the significant broadening of the width of the phase transition and lowering of the main phase-transition temperature in the lipid bilayers. At high concentrations, hydroxy and nonhydroxy analogs appear to form different domains. The correlation of thermal effects with antioxidant activity is discussed.

  9. 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.

  10. 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.

  11. An Investigation of Thermal Characteristic of Mechanical Crimp Textured Polyester Yarn by Differential Scanning Calorimeter (DSC)

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Someshwar S.; Shaikh, Tasnim N.; Pratap, Arun

    2010-06-01

    Deficiencies related to the lack of bulk in flat continuous filament yarns make them unsuitable for apparel, home textiles as well as other applications such as car seat covering. Hence, texturising is employed to impart lofty and bulky characteristics to them. The two major texturising techniques employed for polyester yarn are false-twist and air-jet texturising. Out of these earlier technique depends on the thermoplasticity of the yarn being textured whereas the later one demands subsequent amount of compressed air to carry out cold fluid texturising. A new concept of mechanical crimp texturising has been designed to overcome these limitations of commercially successful techniques. In this new technique, pre-twisted FDY (Fully Drawn Yarn) flat multifilament yarn has been subjected to the higher false-twisting (depending on yarn fineness) action under the condition of underfeed (depending on ductility of parent yarn). The torque caused due to high level of false-twisting, forces the filaments to follow helical path at a certain angle (depends on magnitude of twist and denier per filament) to the filament yarn longitudinal axis. Internal stresses arising in single filaments tend to bend the filament and take the shape of spatial helical spring. After the yarn has passed through the false twisting unit, the initial twist would reassert itself and lock the already formed crimpy convolutions in position. Mechanical crimp textured polyester yarns with different pre-twist and false-twist levels have been subjected to thermal stress analysis using differential Scanning Calorimeter (DSC) in heat-cool-heat mode. The samples were heated at a rate of 10°C/minute. Almost all samples appear to be crystalline in nature. However, the melting endotherm does not show sharp peak. Instead, the diffuse nature of the peak is a signature of a partial crystalline nature (48%) of the samples. After melting the specimens, cooling of the same leads to crystallization of the material

  12. 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

  13. Preliminary Analysis of the Social and Scientific Impact of the UAEM-ININ M.Sc. and D.Sc. Graduate Programme in Medical Physics

    NASA Astrophysics Data System (ADS)

    Mitsoura, Eleni; Isaac-Olive, Keila; Torres-Garcia, Eugenio; Camacho-Lopez, Miguel Angel; Hardy-Perez, Alberto

    2010-12-01

    Sponsored by the International Atomic Energy Agency (IAEA) in 1994, the Instituto Nacional de Investigaciones Nucleares (ININ) started in Mexico a teaching and training programme (Diplomado) in Radiotherapy Medical Physics. Based on this experience, the Universidad Autónoma del Estado de México (UAEM) and the Instituto Nacional de Investigaciones Nucleares (ININ) launched two years later, the first Graduate Programme in Science (M.Sc. and D.Sc.), specialised in Medical Physics in Mexico. A preliminary analysis of the social and scientific impact of the UAEM-ININ Programme is presented in this work based on the achievements attained, regarding the number of graduated Medical Physicists, their geographic and academic origin, their current professional activities and the number of scientific publications produced as a result of the thesis, as well as their citations.

  14. 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)

  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. 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

  17. Cerebral perfusion alterations in epileptic patients during peri-ictal and post-ictal phase: PASL vs DSC-MRI.

    PubMed

    Pizzini, Francesca B; Farace, Paolo; Manganotti, Paolo; Zoccatelli, Giada; Bongiovanni, Luigi G; Golay, Xavier; Beltramello, Alberto; Osculati, Antonio; Bertini, Giuseppe; Fabene, Paolo F

    2013-07-01

    Non-invasive pulsed arterial spin labeling (PASL) MRI is a method to study brain perfusion that does not require the administration of a contrast agent, which makes it a valuable diagnostic tool as it reduces cost and side effects. The purpose of the present study was to establish the viability of PASL as an alternative to dynamic susceptibility contrast (DSC-MRI) and other perfusion imaging methods in characterizing changes in perfusion patterns caused by seizures in epileptic patients. We evaluated 19 patients with PASL. Of these, the 9 affected by high-frequency seizures were observed during the peri-ictal period (within 5hours since the last seizure), while the 10 patients affected by low-frequency seizures were observed in the post-ictal period. For comparison, 17/19 patients were also evaluated with DSC-MRI and CBF/CBV. PASL imaging showed focal vascular changes, which allowed the classification of patients in three categories: 8 patients characterized by increased perfusion, 4 patients with normal perfusion and 7 patients with decreased perfusion. PASL perfusion imaging findings were comparable to those obtained by DSC-MRI. Since PASL is a) sensitive to vascular alterations induced by epileptic seizures, b) comparable to DSC-MRI for detecting perfusion asymmetries, c) potentially capable of detecting time-related perfusion changes, it can be recommended for repeated evaluations, to identify the epileptic focus, and in follow-up and/or therapy-response assessment.

  18. A Shortened Norwegian Adaptation of the Lie Scale for Children (LSC) and the Defensiveness Scale for Children (DSC)

    ERIC Educational Resources Information Center

    Haugen, Richard

    1978-01-01

    Ten items consisting of five DSC items and five LSC items were translated into Norwegian in order (a) to control the verbal anxiety responses from defensive tendencies, (b) to handle the problem of response set (the tendency to answer a questionnaire in a stereotyped way), and (c) to permit research concerning the nature of defensiveness itself.…

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

    SciTech Connect

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

    2006-05-05

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

  20. Transgenic mice overexpressing desmocollin-2 (DSC2) develop cardiomyopathy associated with myocardial inflammation and fibrotic remodeling

    PubMed Central

    Garnett, Lauren; Martens, Kristina; Abdelfatah, Nelly; Rodriguez, Marcela; Diao, Catherine; Chen, Yong-Xiang; Gordon, Paul M. K.; Nygren, Anders; Gerull, Brenda

    2017-01-01

    Background Arrhythmogenic cardiomyopathy is an inherited heart muscle disorder leading to ventricular arrhythmias and heart failure, mainly as a result of mutations in cardiac desmosomal genes. Desmosomes are cell-cell junctions mediating adhesion of cardiomyocytes; however, the molecular and cellular mechanisms underlying the disease remain widely unknown. Desmocollin-2 is a desmosomal cadherin serving as an anchor molecule required to reconstitute homeostatic intercellular adhesion with desmoglein-2. Cardiac specific lack of desmoglein-2 leads to severe cardiomyopathy, whereas overexpression does not. In contrast, the corresponding data for desmocollin-2 are incomplete, in particular from the view of protein overexpression. Therefore, we developed a mouse model overexpressing desmocollin-2 to determine its potential contribution to cardiomyopathy and intercellular adhesion pathology. Methods and results We generated transgenic mice overexpressing DSC2 in cardiac myocytes. Transgenic mice developed a severe cardiac dysfunction over 5 to 13 weeks as indicated by 2D-echocardiography measurements. Corresponding histology and immunohistochemistry demonstrated fibrosis, necrosis and calcification which were mainly localized in patches near the epi- and endocardium of both ventricles. Expressions of endogenous desmosomal proteins were markedly reduced in fibrotic areas but appear to be unchanged in non-fibrotic areas. Furthermore, gene expression data indicate an early up-regulation of inflammatory and fibrotic remodeling pathways between 2 to 3.5 weeks of age. Conclusion Cardiac specific overexpression of desmocollin-2 induces necrosis, acute inflammation and patchy cardiac fibrotic remodeling leading to fulminant biventricular cardiomyopathy. PMID:28339476

  1. Reliable estimation of capillary transit time distributions using DSC-MRI

    PubMed Central

    Mouridsen, Kim; Hansen, Mikkel Bo; Østergaard, Leif; Jespersen, Sune Nørhøj

    2014-01-01

    The regional availability of oxygen in brain tissue is traditionally inferred from the magnitude of cerebral blood flow (CBF) and the concentration of oxygen in arterial blood. Measurements of CBF are therefore widely used in the localization of neuronal response to stimulation and in the evaluation of patients suspected of acute ischemic stroke or flow-limiting carotid stenosis. It was recently demonstrated that capillary transit time heterogeneity (CTH) limits maximum oxygen extraction fraction (OEFmax) that can be achieved for a given CBF. Here we present a statistical approach for determining CTH, mean transit time (MTT), and CBF using dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI). Using numerical simulations, we demonstrate that CTH, MTT, and OEFmax can be estimated with low bias and variance across a wide range of microvascular flow patterns, even at modest signal-to-noise ratios. Mean transit time estimated by singular value decomposition (SVD) deconvolution, however, is confounded by CTH. The proposed technique readily identifies malperfused tissue in acute stroke patients and appears to highlight information not detected by the standard SVD technique. We speculate that this technique permits the non-invasive detection of tissue with impaired oxygen delivery in neurologic disorders such as acute ischemic stroke and Alzheimer's disease during routine diagnostic imaging. PMID:24938401

  2. DSC study of the isothermal crystallization of iPP-CNF nanocomposites

    NASA Astrophysics Data System (ADS)

    Chipara, Dorina M.; Chipara, Mircea

    2013-03-01

    Nanocomposite materials have been obtained by dispersing vapor grown carbon nanofibers (VGCNFs) with diameters ranging between 60 and 100 nm and lengths between 30,000 and 100,000 nm supplied by Pyrograf Products, Inc (PR-24AG) within a polymer matrix - isotactic polypropylene (iPP) - type Marlex HLN-120-01 with density 0.906 g/cm3 and melt flow rate at 230 oC of 12 g/10 min, supplied by Philips Sumika Polypropylene Company. VGCNFs have been purified and disentangled by reflux in dichloromethane and deionized water followed by vacuum filtering (for 24 h) and drying at 110 oC for 24h. The nanocomposites were obtained by melt mixing at 180 oC for 9 minutes with a speed of 65 rpm followed by an additional mixing at 90 rpm for 5 minutes, using a HAAKE Rheomix, Nanocomposites loaded with various amounts of VGCNFs (0%, 1%, 2.5%, 5%, 7.5%, 10%, 15%, and 20% wt.) have been prepared and investigated by TA DSC Q-500. Isothermal crystallization was investigated in detail and analyzed by using an expression derived from the Avrami equation. The effect of the filler on the isothermal crystallization of iPP is discussed in detail. The research is focused on the effect of VGCNF on the degree of crystallization of iPP, crystallization rate, and dimensionality of the crystallization process. This research has been supported by National Science Foundation under DMR. Contract grant number 0934157.

  3. FTIR, XRD and DSC studies of nanochitosan, cellulose acetate and polyethylene glycol blend ultrafiltration membranes.

    PubMed

    Vinodhini, P Angelin; K, Sangeetha; Thandapani, Gomathi; P N, Sudha; Jayachandran, Venkatesan; Sukumaran, Anil

    2017-03-29

    In the present work, a series of novel nanochitosan/cellulose acetate/polyethylene glycol (NCS/CA/PEG) blend flat sheet membranes were fabricated in different ratios (1:1:1, 1:1:2, 2:1:1, 2:1:2, 1:2:1, 2:2:1) in a polar solvent of N,N'-dimethylformamide (DMF) using the most popular phase inversion method. Nanochitosan was prepared by the ionotropic gelation method and its average particle size has been analyzed using Dynamic Light Scattering (DLS) method. The effect of blending of the three polymers was investigated using FTIR and XRD studies. FTIR results confirmed the formation of well-blended membranes and the XRD analysis revealed enhanced amorphous nature of the membrane ratio 2:1:2. DSC study was conducted to find out the thermal behavior of the blend membranes and the results clearly indicated good thermal stability and single glass transition temperature (Tg) of all the prepared membranes. Asymmetric nature and rough surface morphology was confirmed using SEM analysis. From the results it was evident that the blending of the polymers with higher concentration of nanochitosan can alter the nature of the resulting membranes to a greater extent and thus amorphous membranes were obtained with good miscibility and compatibility.

  4. 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

  5. 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.

  6. 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).

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. DSC and TG Analysis of a Blended Binder Based on Waste Ceramic Powder and Portland Cement

    NASA Astrophysics Data System (ADS)

    Pavlík, Zbyšek; Trník, Anton; Kulovaná, Tereza; Scheinherrová, Lenka; Rahhal, Viviana; Irassar, Edgardo; Černý, Robert

    2016-03-01

    Cement industry belongs to the business sectors characteristic by high energy consumption and high {CO}2 generation. Therefore, any replacement of cement in concrete by waste materials can lead to immediate environmental benefits. In this paper, a possible use of waste ceramic powder in blended binders is studied. At first, the chemical composition of Portland cement and ceramic powder is analyzed using the X-ray fluorescence method. Then, thermal and mechanical characterization of hydrated blended binders containing up to 24 % ceramic is carried out within the time period of 2 days to 28 days. The differential scanning calorimetry and thermogravimetry measurements are performed in the temperature range of 25°C to 1000°C in an argon atmosphere. The measurement of compressive strength is done according to the European standards for cement mortars. The thermal analysis results in the identification of temperature and quantification of enthalpy and mass changes related to the liberation of physically bound water, calcium-silicate-hydrates dehydration and portlandite, vaterite and calcite decomposition. The portlandite content is found to decrease with time for all blends which provides the evidence of the pozzolanic activity of ceramic powder even within the limited monitoring time of 28 days. Taking into account the favorable results obtained in the measurement of compressive strength, it can be concluded that the applied waste ceramic powder can be successfully used as a supplementary cementing material to Portland cement in an amount of up to 24 mass%.

  17. Correlation of the penetration enhancement with the influence of an alcohol/tocopheryl polyethylene glycol succinate (TPGS) cosolvent system on the molecular structure of the stratum corneum of nude mouse skin as examined by microscopic FTIR/DSC

    NASA Astrophysics Data System (ADS)

    Liou, Yi-Bo; Ho, Hsiu-O.; Chen, Shin-Yi; Sheu, Ming-Thau

    2009-10-01

    Tocopheryl polyethylene glycol succinate (TPGS) is a water-soluble derivative of natural source of vitamin E, which possesses a dual nature of lipophilicity and hydrophilicity, similar to a surface-active agent. The penetration enhancement of estradiol by an ethanol and TPGS cosolvent system (EtOH/TPGS) has been confirmed. In this study, the correlation of the penetration enhancement with the influence of the EtOH/TPGS cosolvent system on biophysical changes of the stratum corneum (SC) as examined by Fourier transformation infrared spectrometry differential scanning calorimetry (FTIR/DSC) was investigated. Thermotropic changes in the asymmetrical and symmetrical C-H stretching of hydrocarbon chains of lipids, and amide I and II bands that characterize the protein structure of the SC treated with different concentrations of the EtOH/TPGS cosolvent were examined in this investigation. Results demonstrated that a strong correlation of the influence on biophysical changes of the SC treated with the EtOH/TPGS cosolvent system with the penetration enhancement of estradiol by the corresponding cosolvent system was not evident. It was concluded that the incorporation of TPGS in the cosolvent system seemed only to have insignificantly modified the structural features of the SC. It was not obvious that the penetrant had encountered these modifications resulting in an improvement in the penetration of estradiol by TPGS.

  18. Are All-Solid-State Lithium-Ion Batteries Really Safe?-Verification by Differential Scanning Calorimetry with an All-Inclusive Microcell.

    PubMed

    Inoue, Takao; Mukai, Kazuhiko

    2017-01-18

    Although all-solid-state lithium-ion batteries (ALIBs) have been believed as the ultimate safe battery, their true character has been an enigma so far. In this paper, we developed an all-inclusive-microcell (AIM) for differential scanning calorimetry (DSC) analysis to clarify the degree of safety (DOS) of ALIBs. Here AIM possesses all the battery components to work as a battery by itself, and DOS is determined by the total heat generation ratio (ΔH) of ALIB compared with the conventional LIB. When DOS = 100%, the safety of ALIB is exactly the same as that of LIB; when DOS = 0%, ALIB reaches the ultimate safety. We investigated two types of LIB-AIM and three types of ALIB-AIM. Surprisingly, all the ALIBs exhibit one or two exothermic peaks above 250 °C with 20-30% of DOS. The exothermic peak is attributed to the reaction between the released oxygen from the positive electrode and the Li metal in the negative electrode. Hence, ALIBs are found to be flammable as in the case of LIBs. We also attempted to improve the safety of ALIBs and succeeded in decreasing the DOS down to ∼16% by incorporating Ketjenblack into the positive electrode as an oxygen scavenger. Based on ΔH as a function of voltage window, a safety map for LIBs and ALIBs is proposed.

  19. Identification and quantification of the crystalline structures of poly(vinylidene fluoride) sutures by wide-angle X-ray scattering and differential scanning calorimetry.

    PubMed

    Laroche, G; Lafrance, C P; Prud'homme, R E; Guidoin, R

    1998-02-01

    The outstanding biocompatibility of the polyvinylidene fluoride (PVDF) monofilament suture together with other desirable characteristics, such as ease of handling and resistance to biodegradation, makes it an attractive alternative monofilament suture material for cardiovascular surgery. However, to achieve a high performance suture, the polymeric raw material must be exposed to different treatments, which lead to different degrees and types of crystallization. Since these crystalline modifications deeply influence the mechanical characteristics and the biostability of the sutures, the authors hereby propose a method of quantifying the different structures of PVDF using wide angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). The commercial devices are achieved by coloring and processing the polymeric raw material. The white and unprocessed 4-0 unswaged suture presents 19% of the alpha phase, 38% of the beta structure, and no gamma form. Coloration increases the amount of the beta phase by 5-9% at the expense of the alpha phase. On the other hand, processing the fibers lead to the conversion of some of the amorphous phase to the gamma structure, the importance of which is 6-7%. Finally, tensile measurements performed on the different PVDF fibers clearly proves that their mechanical characteristics depend on the presence of these crystalline forms in the polymeric structure of PVDF.

  20. Thermotropic phase behaviour of alpha-dipalmitoylphosphatidylcholine multibilayers is influenced to various extents by carotenoids containing different structural features--evidence from differential scanning calorimetry.

    PubMed

    Kostecka-Gugała, Anna; Latowski, Dariusz; Strzałka, Kazimierz

    2003-01-31

    Carotenoids are the effective modulators of physical properties of model and natural membranes. To demonstrate the relationship between the structure of carotenoids and their effect on the molecular dynamics of membranes, we have investigated the influence of five structurally different carotenoids: beta-carotene, lycopene, lutein, violaxanthin, zeaxanthin and additionally carotane--a fully saturated derivative of beta-carotene, on thermotropic phase behaviour of dipalmitoylphosphatidylcholine (DPPC) multilamellar vesicles by means of differential scanning calorimetry (DSC). The results obtained indicate that the carotenoids used modulated the thermotropic properties of multibilayers to various extents, broadening the pretransition and the main phase transition peaks and shifting them to lower temperatures. Pronounced decrease of pretransition enthalpy (DeltaH(p)) proves that carotenoids very strongly alter the membrane properties in its gel phase. Comparison of the influence of several carotenoids shows that a rigid, polyisoprenoid chain plays a basic role in altering the thermotropic properties of such membranes and the presence of rings without oxygen-containing groups has a minor significance for the observed interactions. Carotenoids containing epoxy and/or hydroxy groups attached to their rings modify the thermotropic phase behaviour of DPPC multilamellar vesicles stronger than carotenes--a result of their orientation in the DPPC bilayer.

  1. 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

  2. Prediction of the Long-term Efficacy of STA-MCA Bypass by DSC-PI

    PubMed Central

    Hui, Li; Hui, Liu

    2016-01-01

    Abstract Superficial temporal artery-middle cerebral artery (STA-MCA) bypass [1,2] is an important and effective type of surgical revascularization that is widely used in the treatment of ischemic cerebral artery disease. However, a means of predicting its postoperative efficacy has not been established [3,4]. The present study analyzes the correlation between preoperative perfusion parameters (obtained using dynamic susceptibility contrast-enhanced perfusion imaging, DSC-PI) and postoperative long-term prognosis (using modified Rankin Scale, mRS scores). The preoperative perfusion parameters were defined by a combination of perfusion-weighted imaging and the Alberta Stroke Program Early Computerized Tomography Score (PWI-ASPECTS) and included cerebral blood flow (CBF)-ASPECTS, cerebral blood volume (CBV)-ASPECTS, mean transit time (MTT)-ASPECTS, and time to peak (TTP)-ASPECTS. Preoperative and postoperative scores were determined for 33 patients that received a unilateral STA-MCA bypass in order to discover the most reliable imaging predictive index as well as to define the threshold value for a favorable clinical outcome. The results showed that all of the PWI-ASPECTS scores were significantly negatively correlated with clinical prognosis. Receiver operating curve (ROC) analysis of the preoperative parameters in relation to long term prognosis showed the area under curve (AUC) was maximal for the CBF-ASPECTS score (P = 0.002). A preoperative score of less than six indicated a poor postoperative prognosis (sensitivity = 74.1%, specificity = 100%, AUC = 0.843). In conclusion, preoperative PWI-ASPECTS scores have been found useful as predictive indexes for the long-term prognosis of STA-MCA bypass patients, with higher scores indicating better postoperative long-term outcomes. As the most valuable prognostic indicator, the preoperative CBF-ASPECTS score has potential for use as a major index in screening and outcome prediction of patients under consideration for STA

  3. Crystallization kinetics of orthorhombic paracetamol from supercooled melts studied by non-isothermal DSC.

    PubMed

    Nikolakakis, Ioannis; Kachrimanis, Kyriakos

    2017-02-01

    A simple and highly reproducible procedure was established for the study of orthorhombic paracetamol crystallization kinetics, comprising melting, quench-cooling of the melt and scanning the formed glass by DSC at different heating rates. Results were analyzed on the basis of the mean as well as local values of the Avrami exponent, n, the energy of activation, as well as the Šesták-Berggren two-parameter autocatalytic kinetic model. The mean value of the Avrami kinetic exponent, n, ranged between 3 and 5, indicating deviation from the nucleation and growth mechanism underlying the Johnson-Mehl, Avrami-Kolmogorov (JMAK) model. To verify the extent of the deviation, local values of the Avrami exponent as a function of the volume fraction transformed were calculated. Inspection of the local exponent values indicates that the crystallization mechanism changes over time, possibly reflecting the uncertainty of crystallization onset, instability of nucleation due to an autocatalytic effect of the crystalline phase, and growth anisotropy due to impingement of spherulites in the last stages of crystallization. The apparent energy of activation, Ea, has a rather low mean value, close to 81 kJ/mol, which is in agreement with the observed instability of glassy-state paracetamol. Isoconversional methods revealed that Ea tends to decrease with the volume fraction transformed, possibly because of the different energy demands of nucleation and growth. The exponents of the Šesták-Berggren two-parameter model showed that the crystallized fraction influences the process, confirming the complexity of the crystallization mechanism.

  4. Prediction of the Long-term Efficacy of STA-MCA Bypass by DSC-PI.

    PubMed

    Hui, Li; Hui, Liu; Tong, Han

    2016-01-01

    Superficial temporal artery-middle cerebral artery (STA-MCA) bypass [1,2] is an important and effective type of surgical revascularization that is widely used in the treatment of ischemic cerebral artery disease. However, a means of predicting its postoperative efficacy has not been established [3,4]. The present study analyzes the correlation between preoperative perfusion parameters (obtained using dynamic susceptibility contrast-enhanced perfusion imaging, DSC-PI) and postoperative long-term prognosis (using modified Rankin Scale, mRS scores). The preoperative perfusion parameters were defined by a combination of perfusion-weighted imaging and the Alberta Stroke Program Early Computerized Tomography Score (PWI-ASPECTS) and included cerebral blood flow (CBF)-ASPECTS, cerebral blood volume (CBV)-ASPECTS, mean transit time (MTT)-ASPECTS, and time to peak (TTP)-ASPECTS. Preoperative and postoperative scores were determined for 33 patients that received a unilateral STA-MCA bypass in order to discover the most reliable imaging predictive index as well as to define the threshold value for a favorable clinical outcome. The results showed that all of the PWI-ASPECTS scores were significantly negatively correlated with clinical prognosis. Receiver operating curve (ROC) analysis of the preoperative parameters in relation to long term prognosis showed the area under curve (AUC) was maximal for the CBF-ASPECTS score (P = 0.002). A preoperative score of less than six indicated a poor postoperative prognosis (sensitivity = 74.1%, specificity = 100%, AUC = 0.843). In conclusion, preoperative PWI-ASPECTS scores have been found useful as predictive indexes for the long-term prognosis of STA-MCA bypass patients, with higher scores indicating better postoperative long-term outcomes. As the most valuable prognostic indicator, the preoperative CBF-ASPECTS score has potential for use as a major index in screening and outcome prediction of patients under consideration for STA

  5. PREFACE: XVth International Conference on Calorimetry in High Energy Physics (CALOR2012)

    NASA Astrophysics Data System (ADS)

    Akchurin, Nural

    2012-12-01

    reconstruction and trigger of jets, missing transverse energy, electrons, photons, and taus. Pile-up, anomalous signals, and noise mitigation techniques were also discussed in the conference. On the last day, several future R&D initiatives were presented: highly granular CALICE with different technology options and plans for the dual-readout DREAM projects were the main topics. Although these approaches are quite different conceptually, future experiments will certainly benefit from their innovations. Concluding remarks by the chair of the organizing committee, Nural Akchurin (TTU), summarized the highlights of the conference and invited proposals to host the CALOR2014 conference in Europe, as the conference venue rotates between the Americas, Europe, and Asia every two years. We strived hard to keep the cost of this conference as low as possible without sacrificing the scientific mission. I am delighted to report that we were able to provide support for six junior colleagues to participate in this conference. I am also grateful to the institutions, industrial partners, and agencies that provided the support that made a lot possible: Texas Tech University, the University of New Mexico, Los Alamos National Laboratory, the US Department of Energy, CAEN, and the Wiener Plein & Baus, Corp. I also would like to thank the session conveners who organized sessions and reviewed the papers. The members of the local organizing committee were instrumental to the success of this conference: their experience and attention to detail were invaluable. Most of all, I extend my appreciation to the conference participants and to all my other colleagues who continue to enrich the field of calorimetry through their hard work and creativity. The future is bright. Nural Akchurin Chair of the Organizing Committee International Advisory Committee: Mikhail Danilov, ITEP Moscow Marcella Diemoz, INFN Roma I Antonio Ereditato, Univ. of Bern Franco L. Fabbri, INFN Frascati Tomio Kobayashi, ICEPP Tokyo Michele

  6. Tg-Confinement Effects in Polymer Thin Films, Nanotubes, and Nanospheres as Measured by DSC, Ellipsometry and Fluorescence

    NASA Astrophysics Data System (ADS)

    Torkelson, John; Tan, Anthony; Chen, Lawrence

    The effect of nanoscale confinement on the glass transition temperature (Tg) of supported and free-standing polymer films has been studied for two decades by various techniques. However, conventional DSC, which is the most common method for measuring Tg of bulk polymers, is not well suited for such measurements. Here, we demonstrate that Tg-confinement effects measured by conventional DSC in nanotubes of polymer supported in anodic aluminum oxide (AAO) templates compare well with with Tg-confinement effects measured in supported polymer films by ellipsometry and fluorescence. We further show that Tg-confinement effect data for nanotubes obtained by fluorescence agree well with data obtained by DSC. Finally, we draw comparisons between the Tg-confinement behavior of nanoprecipitated polymer nanospheres as measured by fluorescence to Tg-confinement effects for both supported and free-standing polymer films. The roles, if any, of confinement dimensionality (1-D vs 2-D vs 3-D) and measurement technique on the observed Tg-confinement effect will be discussed.

  7. Characterization of wrist-wearable activity measurement using whole body calorimetry in semi-free living conditions.

    PubMed

    Amor, James D; Hattersley, John G; Barber, Thomas M; James, Christopher J

    2015-08-01

    Physical activity (PA) is a significant factor in a number of health conditions and monitoring PA can play a significant role in the treatment of, or research into, these conditions. For longitudinal monitoring of PA, unobtrusive devices are often used and there is a need for the development of energy expenditure (EE) estimation techniques from single-device systems. This paper presents an experiment designed to characterize the relationship between a previously described technique, the activity score (AS) and EE obtained from whole-room indirect calorimetry. The study used 8 participants over a 24-hr period with interspersed exercise periods to observe physical movement with wearable devices and EE in 5 minute epochs. Results show that AS and EE are correlated with a Spearman's rank correlation coefficient of 0.775 with p <; 0.001.

  8. 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.

  9. Determination of the Heat of Combustion of Biodiesel Using Bomb Calorimetry: A Multidisciplinary Undergraduate Chemistry Experiment

    ERIC Educational Resources Information Center

    Akers, Stephen M.; Conkle, Jeremy L.; Thomas, Stephanie N.; Rider, Keith B.

    2006-01-01

    Biodiesel was synthesized by transesterification of waste vegetable oil using common glassware and reagents, and characterized by measuring heat of combustion, cloud point, density and measuring the heat of combustion and density together allows the student the energy density of the fuel. Analyzing the biodiesel can serve as a challenging and…

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Characterization of parvalbumin and polcalcin divalent ion binding by isothermal titration calorimetry.

    PubMed

    Henzl, Michael T

    2009-01-01

    The elucidation of structure-affinity relationships in EF-hand proteins requires a reliable assay of divalent ion affinity. In principle, isothermal titration calorimetry (ITC) should be capable of furnishing estimates for Ca2+- and Mg2+-binding constants in these systems. And because the method yields the binding enthalpy directly, ITC can provide a more detailed view of binding energetics than methods that rely on 45Ca2+ or fluorescent indicators. For several reasons, however, it is generally not possible to extract reliable binding parameters from single ITC experiments. Ca2+ affinity is often too high, and Mg2+ affinity is invariably too low. Moreover, least-squares minimization of multisite systems may not afford a unique fit because of strong parameter correlations. This chapter outlines a strategy for analyzing two-site systems that overcomes these obstacles. The method--which involves simultaneous, or global, least-squares analysis of direct and competitive ITC data--yields binding parameters for both Ca2+ and Mg2+. Application of the method is demonstrated for two systems. The S55D/E59D variant of rat alpha-parvalbumin, noteworthy for its elevated metal ion affinity, binds divalent ions noncooperatively and is amenable to analysis using an independent two-site model. On the other hand, Phl p 7, a pollen-specific EF-hand protein from timothy grass, binds Ca2+ with positive cooperativity. Divalent ion-binding data for the protein must be analyzed using a two-site Adair model.

  15. 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.

  16. 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.

  17. A novel compound DSC suppresses lipopolysaccharide-induced inflammatory responses by inhibition of Akt/NF-κB signalling in macrophages.

    PubMed

    Liu, Xin-Hua; Pan, Li-Long; Jia, Yao-Ling; Wu, Dan; Xiong, Qing-Hui; Wang, Yang; Zhu, Yi-Zhun

    2013-05-15

    A novel compound [4-(2-acetoxy-3-((R)-3-(benzylthio)-1-methoxy-1-oxopropan-2-ylamino)-3-oxopropyl)-1,2-phenylene diacetate (DSC)], derived from Danshensu, exerted cytoprotective effects by anti-oxidative and anti-apoptotic activities in vitro. Herein, we reported the protective effects of DSC on lipopolysaccharide (LPS)-induced inflammatory responses in murine RAW264.7 macrophages and the underlying mechanisms. We showed that DSC concentration-dependently attenuated nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) expression with less cytotoxicity. Signal transduction studies indicated that DSC significantly inhibited LPS-induced phosphorylation of Akt, but not c-Jun N-terminal kinase 1/2, p38, or extracellular signal-regulated kinase 1/2. Meanwhile, LPS-induced nuclear translocation of nuclear factor-κB (NF-κB) p65 was decreased by DSC. Furthermore, a phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 significantly suppressed LPS-induced NF-κB p65 nuclear translocation, iNOS expression, and NO production, which was also mimicked by pretreatment with DSC. These results suggested that DSC attenuated LPS-induced inflammatory response in macrophages, at least in part, through suppression of PI3K/Akt signaling and NF-κB activation.

  18. 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.

  19. 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.

  20. 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.

  1. Proceedings of the Eleventh International Conference on Calorimetry in Particle Physics

    NASA Astrophysics Data System (ADS)

    Cecchi, Claudia

    The Pamela silicon tungsten calorimeter / G. Zampa -- Design and development of a dense, fine grained silicon tungsten calorimeter with integrated electronics / D. Strom -- High resolution silicon detector for 1.2-3.1 eV (400-1000 nm) photons / D. Groom -- The KLEM high energy cosmic rays collector for the NUCLEON satellite mission / M. Merkin (contribution not received) -- The electromagnetic calorimeter of the Hera-b experiment / I. Matchikhilian -- The status of the ATLAS tile calorimeter / J. Mendes Saraiva -- Design and mass production of Scintillator Pad Detector (SPD) / Preshower (PS) detector for LHC-b experiment / E. Gushchin -- Study of new FNAL-NICADD extruded scintillator as active media of large EMCal of ALICE at LHC / O. Grachov -- The CMS hadron calorimeter / D. Karmgard (contribution not received) -- Test beam study of the KOPIO Shashlyk calorimeter prototype / A. Poblaguev -- The Shashlik electro-magnetic calorimeter for the LHCb experiment / S. Barsuk -- Quality of mass produced lead-tungstate crystals / R. Zhu -- Status of the CMS electromagnetic calorimeter / J. Fay -- Scintillation detectors for radiation-hard electromagnetic calorimeters / H. Loehner -- Energy, timing and two-photon invariant mass resolution of a 256-channel PBWO[symbol] calorimeter / M. Ippolitov -- A high performance hybrid electromagnetic calorimeter at Jefferson Lab / A. Gasparian -- CsI(Tl) calorimetry on BESHI / T. Hu (contribution not received) -- The crystal ball and TAPS detectors at the MAMI electron beam facility / D. Watts -- Front-end electronics of the ATLAS tile calorimeter / R. Teuscher -- The ATLAS tilecal detector control system / A. Gomes -- Performance of the liquid argon final calibration board / C. de la Taille -- Overview of the LHCb calorimeter electronics / F. Machefert -- LHCb preshower photodetector and electronics / S. Monteil -- The CMS ECAL readout architecture and the clock and control system / K. Kloukinas -- Test of the CMS-ECAL trigger

  2. The importance of high-precision hadronic calorimetry to physics

    NASA Astrophysics Data System (ADS)

    Hauptman, John

    2016-11-01

    The reconstruction and high-precision measurement of the four-vectors of W and Z decays to quarks, which constitute nearly 70% of their decay branching fractions, are critical to a high efficiency and high quality experiment. Furthermore, it is crucial that the energy resolution, and consequently the resolution on the invariant mass of the two fragmenting quarks, is comparable to the energy-momentum resolution on the other particles of the standard model, in particular, electrons, photons, and muons, at energies around 100 GeV. I show that this “unification of resolutions” on all particles of the standard model is now in sight, and will lead to excellent physics at an electron-positron collider.

  3. 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.

  4. 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.

  5. 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.

  6. 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...

  7. 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.

  8. 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...

  9. 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…

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Dysspondyloenchondromatosis (DSC) associated with COL2A1 mutation: Clinical and radiological overlap with spondyloepimetaphyseal dysplasia-Strudwick type (SEMD-S).

    PubMed

    Merrick, Blair; Calder, Alistair; Wakeling, Emma

    2015-12-01

    Dysspondyloenchondromatosis (DSC) is a rare skeletal dysplasia characterized by enchondroma-like lesions and anisospondyly. The former leads to discrepancies in limb length, and the latter, to progressive kyphoscoliosis. Two recent cases have highlighted the genetic heterogeneity of DSC, one demonstrating the presence and, the other, the absence of a COL2A1 mutation. This may have important clinical implications, for example, screening for complications including atlanto-axial instability associated with type II collagenopathies, as well as long-term patient management. We report on a case with radiographic features of DSC with overlap into the type II collagenopathy spondyloepimetaphyseal dysplasia, Strudwick type, who was found to carry a novel heterozygous mutation in the COL2A1 gene. Testing for COL2A1 mutations should be performed in all patients with radiological features of DSC. Further research is needed to identify the underlying molecular cause in cases where no COL2A1 mutation is identified.

  16. A Simple Method to Estimate the Critical Temperature of Thermal Explosion for Energetic Materials Using Nonisothermal DSC

    NASA Astrophysics Data System (ADS)

    Xue, L.; Zhao, F. Q.; Hu, R. Z.; Gao, H. X.

    2010-01-01

    A method for estimating critical temperature (T b) of thermal explosion for energetic materials was derived from Semenov's [9] thermal explosion theory and the nonisothermal kinetic equation ? based on Berthelot's expression using reasonable hypotheses. The final formula is ? , which is simple. We can easily obtain the onset temperature (T ei) from the nonisothermal DSC curves, the value of T e0 from the equation ? , the values of b from the equation ? , and then calculate the value of T b. The result obtained with this method coincides completely with the value of T b obtained by Zhang et al.'s [4] method.

  17. 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.

  18. 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.

  19. 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

  20. Analysis of Siderite Thermal Decomposition by Differential Scanning Calorimetry

    NASA Technical Reports Server (NTRS)

    Bell, M. S.; Lin, I.-C.; McKay, D. S.

    2000-01-01

    Characterization of carbonate devolitilization has important implications for atmospheric interactions and climatic effects related to large meteorite impacts in platform sediments. On a smaller scale, meteorites contain carbonates which have witnessed shock metamorphic events and may record pressure/temperature histories of impact(s). ALH84001 meteorite contains zoned Ca-Mg-Fe-carbonates which formed on Mars. Magnetite crystals are found in the rims and cores of these carbonates and some are associated with void spaces leading to the suggestion by Brearley et al. that the crystals were produced by thermal decomposition of the carbonate at high temperature, possibly by incipient shock melting or devolitilization. Golden et al. recently synthesized spherical Mg-Fe-Ca-carbonates from solution under mild hydrothermal conditions that have similar carbonate compositional zoning to those of ALH84001. They have shown experimental evidence that the carbonate-sulfide-magnetite assemblage in ALH84001 can result from a multistep inorganic process involving heating possibly due to shock events. Experimental shock studies on calcium carbonate prove its stability to approx. 60 GPa, well in excess of the approx. 45 GPa peak pressures indicated by other shock features in ALH84001. In addition, Raman spectroscopy of carbonate globules in ALH84001 indicates no presence of CaO and MgO. Such oxide phases should be found associated with the magnetites in voids if these magnetites are high temperature shock products, the voids resulting from devolitilization of CO2 from calcium or magnesium carbonate. However, if the starting material was siderite (FeCO3), thermal breakdown of the ALH84001 carbonate at 470 C would produce iron oxide + CO2. As no documentation of shock effects in siderite exists, we have begun shock experiments to determine whether or not magnetite is produced by the decomposition of siderite within the < 45GPa pressure window and by the resultant thermal pulse to approx

  1. Temperature-controlled poly(propylene) glycol hydrophobicity on the formation of inclusion complexes with modified cyclodextrins. A DSC and ITC study.

    PubMed

    De Lisi, R; Lazzara, G; Milioto, S

    2011-07-21

    The study highlighted the main forces driving the formation of hydroxypropyl-cyclodextrins (HP-CDs) + poly(propylene) glycol 725 g mol(-1) inclusion complexes. The temperature parameter was chosen as the variable to modulate the hydrophobicity of the polymer, and consequently ITC experiments as functions of temperature as well as DSC measurements were done in a systematic way. The polymer is not included into HP-α-CD, it is strongly bound to HP-β-CD and it is floating in HP-γ-CD. The stability of the inclusion complexes is entropy controlled. The gain of the entropy is a unique result compared to the opposite literature findings for inclusion complexes based on polymers and CDs. This peculiarity is ascribable to the removal of water molecules from cages during complexation and this effect compensates the entropy loss due to constraints caused by the CD threading. In spite the host-guest van der Waals contacts are optimized, the enthalpies for the inclusion complex formation are positive and reveal the large heat required for dehydrating the propylene oxide units. All the macrocycles enhanced the polymer solubility in water. Increasing the affinity of the macrocycle to the macromolecule makes more expanded the one-phase area of the binodal curve. A new thermodynamic approach was proposed to predict quantitatively the binodal curve as well as the dependence of the enthalpy of separation phase on the macrocycle composition. The agreement between the experimental data and the computed values was excellent.

  2. Binding of cationic peptides (KX)4K to DPPG bilayers. Increasing the hydrophobicity of the uncharged amino acid X drives formation of membrane bound β-sheets: A DSC and FT-IR study.

    PubMed

    Hädicke, André; Blume, Alfred

    2016-06-01

    The binding of cationic peptides of the sequence (KX)4K to lipid vesicles of negatively charged dipalmitoyl-phosphatidylglycerol (DPPG) was investigated by differential scanning calorimetry (DSC) and temperature dependent Fourier-transformed infrared (FT-IR) spectroscopy. The hydrophobicity of the uncharged amino acid X was changed from G (glycine) over A (alanine), Abu (α-aminobutyric acid), V (valine) to L (leucine). The binding of the peptides caused an increase of the phase transition temperature (Tm) of DPPG by up to 20°C. The shift depended on the charge ratio and on the hydrophobicity of the amino acid X. Unexpectedly, the upward shift of Tm increased with increasing hydrophobicity of X. FT-IR spectroscopy showed a shift of the CH2 stretching vibrations of DPPG to lower frequency, particularly for bilayers in the liquid-crystalline phase, indicating an ordering of the hydrocarbon chains when the peptides were bound. Changes in the lipid C=O vibrational band indicated a dehydration of the lipid headgroup region after peptide binding. (KG)4K was bound in an unordered structure at all temperatures. All other peptides formed intermolecular antiparallel β-sheets, when bound to gel phase DPPG. However, for (KA)4K and (KAbu)4K, the β-sheets converted into an unordered structure above Tm. In contrast, the β-sheet structures of (KV)4K and (KL)4K remained stable even at 80°C when bound to the liquid-crystalline phase of DPPG. Strong aggregation of DPPG vesicles occurred after peptide binding. For the aggregates, we suggest a structure, where aggregated single β-sheets are sandwiched between opposing DPPG bilayers with a dehydrated interfacial region.

  3. Use of DSC and DMA Techniques to Help Investigate a Material Anomaly for PTFE Used in Processing a Piston Cup for the Urine Processor Assembly (UPA) on International Space Station (ISS)

    NASA Technical Reports Server (NTRS)

    Wingard, Doug

    2010-01-01

    Human urine and flush water are eventually converted into drinking water with the Urine Processor Assembly (UPA) aboard the International Space Station (ISS). This conversion is made possible through the Distillation Assembly (DA) of the UPA. One component of the DA is a molded circular piston cup made of virgin polytetrafluoroethylene (PTFE). The piston cup is assembled to a titanium component using eight fasteners and washers. Molded PTFE produced for spare piston cups in the first quarter of 2010 was different in appearance and texture, and softer than material molded for previous cups. For the suspect newer PTFE material, cup fasteners were tightened to only one-half the required torque value, yet the washers embedded almost halfway into the material. The molded PTFE used in the DA piston cup should be Type II, based on AMS 3667D and ASTM D4894 specifications. The properties of molded PTFE are considerably different between Type I and II materials. Engineers working with the DA thought that if Type I PTFE was molded by mistake instead of Type II material, that could have resulted in the anomalous material properties. Typically, the vendor molds flat sheet PTFE from the same material lot used to mold the piston cups, and tensile testing as part of quality control should verify that the PTFE is Type II material. However, for this discrepant lot of material, such tensile data was not available. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) were two of the testing techniques used at the NASA/Marshall Space Flight Center (MSFC) to investigate the anomaly for the PTFE material. Other techniques used on PTFE specimens were: Shore D hardness testing, tensile testing on dog bone specimens and a qualitative estimation of porosity by optical and scanning electron microscopy.

  4. An efficient computational approach to characterize DSC-MRI signals arising from three-dimensional heterogeneous tissue structures.

    PubMed

    Semmineh, Natenael B; Xu, Junzhong; Boxerman, Jerrold L; Delaney, Gary W; Cleary, Paul W; Gore, John C; Quarles, C Chad

    2014-01-01

    The systematic investigation of susceptibility-induced contrast in MRI is important to better interpret the influence of microvascular and microcellular morphology on DSC-MRI derived perfusion data. Recently, a novel computational approach called the Finite Perturber Method (FPM), which enables the study of susceptibility-induced contrast in MRI arising from arbitrary microvascular morphologies in 3D has been developed. However, the FPM has lower efficiency in simulating water diffusion especially for complex tissues. In this work, an improved computational approach that combines the FPM with a matrix-based finite difference method (FDM), which we call the Finite Perturber the Finite Difference Method (FPFDM), has been developed in order to efficiently investigate the influence of vascular and extravascular morphological features on susceptibility-induced transverse relaxation. The current work provides a framework for better interpreting how DSC-MRI data depend on various phenomena, including contrast agent leakage in cancerous tissues and water diffusion rates. In addition, we illustrate using simulated and micro-CT extracted tissue structures the improved FPFDM along with its potential applications and limitations.

  5. Formation of Cholesterol Bilayer Domains Precedes Formation of Cholesterol Crystals in Cholesterol/Dimyristoylphosphatidylcholine Membranes: EPR and DSC Studies

    PubMed Central

    Mainali, Laxman; Raguz, Marija; Subczynski, Witold K.

    2013-01-01

    Saturation-recovery EPR along with DSC were used to determine the cholesterol content at which pure cholesterol bilayer domains (CBDs) and cholesterol crystals begin to form in dimyristoylphosphatidylcholine (DMPC) membranes. To preserve compositional homogeneity throughout the membrane suspension, lipid multilamellar dispersions were prepared using a rapid solvent exchange method. The cholesterol content increased from 0 to 75 mol%. With spin-labeled cholesterol analogs it was shown that the CBDs begin to form at ~50 mol% cholesterol. It was confirmed by DSC that the cholesterol solubility threshold for DMPC membranes is detected at ~66 mol% cholesterol. At levels above this cholesterol content, monohydrate cholesterol crystals start to form. The major finding is that formation of CBDs precedes formation of cholesterol crystals. The region of the phase diagram for cholesterol contents between 50 and 66 mol% is described as a structured one-phase region in which CBDs have to be supported by the surrounding DMPC bilayer saturated with cholesterol. Thus, the phase boundary located at 66 mol% cholesterol separates the structured one-phase region (liquid-ordered phase of DMPC with CBDs) from the two-phase region where the structured liquid-ordered phase of DMPC coexists with cholesterol crystals. It is likely that CBDs are precursors of monohydrate cholesterol crystals. PMID:23834375

  6. Determination of microplastic polyethylene (PE) and polypropylene (PP) in environmental samples using thermal analysis (TGA-DSC).

    PubMed

    Majewsky, Marius; Bitter, Hajo; Eiche, Elisabeth; Horn, Harald

    2016-10-15

    Microplastics are increasingly detected in the environment and the consequences on water resources and ecosystems are not clear to date. The present study provides a cost-effective and straightforward method to determine the mass concentrations of polymer types using thermal analysis. Characteristic endothermic phase transition temperatures were determined for seven plastic polymer types using TGA-DSC. Based on that, extracts from wastewater samples were analyzed. Results showed that among the studied polymers, only PE and PP could be clearly identified, while the phase transition signals of the other polymers largely overlap each other. Subsequently, calibration curves were run for PE and PP for qualitative measurements. 240 and 1540mg/m(3) of solid material (12µm to 1mm) was extracted from two wastewater effluent samples of a municipal WWTP of which 34% (81mg/m(3)) and 17% (257mg/m(3)) could be assigned to PE, while PP was not detected in any of the samples. The presented application of TGA-DSC provides a complementary or alternative method to FT-IR analyses for the determination of PE and PP in environmental samples.

  7. Morphology development upon melting of ultrahigh molecular weight polyethylene formed at high pressure by Ultra SAXS and DSC

    NASA Astrophysics Data System (ADS)

    Wang, Zhigang; Wang, Xuehui; Stribeck, Norbert; Hsiao, Benjamin S.; Han, Charles C.

    2001-03-01

    The morphology development on the melting of ultrahigh molecular weight polyethylenes (UHMWPE), formed from melt crystallization at high different pressures, was studied by ultra small-angle X-ray scattering (USAXS)and DSC. The heating rate used was 5C/min. At 41M psi, UHMWPEs show dominant chain-extended lamellae (CEL) at Mw 4MM, 5MM and 6MM. At 30M psi, UHMWPEs show dominant chain-folding lamellae (CFL) at Mw 4MM, 5MM and 6MM. At 35M psi, UHMWPEs show both CEL and CFL at Mw 5MM and 6MM and a dominant CFL at Mw 4MM. With dominant CFL, USAXS shows a measurable long spacing, which increases with temperature. With dominant CEL, USAXS shows an immeasurable long spacing and relatively strong ultra-small angle scattering intensity. The integrated scattering intensity shows an exponential increase with temperature. The thickest CEL and CFL melt at the end of the DSC endotherm, where the USAXS (corrected for melt scattering) shows a diffuse profile only. This CEL or CFL thickness was estimated using an approach based on the single lamella structure factor. The results show a largest thickness about 100nm for CEL and about 50nm for CFL. Acknowledgement: This work was supported by a NSF grant (DMR 9732653).

  8. 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

  9. Study of polymorphic transformation of ornidazole drug by differential scanning calorimetry and other complementary techniques.

    PubMed

    Desai, Satish R; Dharwadkar, Sanjiv R

    2008-01-01

    Differential scanning calorimetric (DSC) curves recorded for ornidazole drug during heating and cooling showed that the drug which melted around 86.1 degrees C undercooled to well below ambient room temperature of 27 degrees C during the cooling cycle. The undercooled melt kept in the freezer at 0 degree C for 10 days duration also remained in the viscous liquid form. This liquid on taking out from the freezer after ten days and ageing at ambient room temperature of 27 degrees C for 12 h transformed into white powder. The DSC pattern recorded for this white powder consisted of two prominent endothermic peaks beginning at 73.2 and 85.9 degrees C, respectively, suggesting that the powder consisted of a mixture of more than one phase. The X-ray diffraction (XRD) pattern recorded for this powder showed it to be a mixture of semi-crystalline phase and the original compound. The semi-crystalline phase melted at 73.2 degrees C prior to the melting of original compound at 85.9 degrees C. This phase on further ageing for 7 days transforms almost completely to its original form. DSC observations were corroborated by XRD and scanning electron microscopy (SEM) techniques.

  10. 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.

  11. Inherent limitations of fixed-time, servo-controlled radiometric calorimetry

    SciTech Connect

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

    1987-01-01

    Interest has been shown in using fixed-time, servo-controlled calorimetry to shorten the measurement times for certain samples that require low precision values (3 to 5%). This type of calorimeter measurement could be particularly useful for screening scrap samples to determine whether there is a need for a more accurate measurement or for certain confirmatory measurements for which low precision numbers are sufficient. The equipment required for this type of measurement is a servo-controlled calorimeter and a preconditioning unit. Samples to be measured are placed in the preconditioning unit, which is maintained at the internal temperature of the calorimeter. The power value for the sample is determined at a fixed time after loading into the calorimeter, for example, 30 min. When a calorimeter is operated using a fixed cutoff time, there are additional sources of uncertainty that need to be considered. The major factors affecting the uncertainty of the calorimetry power values are discussed. 2 refs., 4 figs.

  12. 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.

  13. Laser Calorimetry Spectroscopy for ppm-level Dissolved Gas Detection and Analysis

    PubMed Central

    K. S., Nagapriya; Sinha, Shashank; R., Prashanth; Poonacha, Samhitha; Chaudhry, Gunaranjan; Bhattacharya, Anandaroop; Choudhury, Niloy; Mahalik, Saroj; Maity, Sandip

    2017-01-01

    In this paper we report a newly developed technique – laser calorimetry spectroscopy (LCS), which is a combination of laser absorption spectroscopy and calorimetry - for the detection of gases dissolved in liquids. The technique involves determination of concentration of a dissolved gas by irradiating the liquid with light of a wavelength where the gas absorbs, and measuring the temperature change caused by the absorbance. Conventionally, detection of dissolved gases with sufficient sensitivity and specificity was done by first extracting the gases from the liquid and then analyzing the gases using techniques such as gas chromatography. Using LCS, we have been able to detect ppm levels of dissolved gases without extracting them from the liquid. In this paper, we show the detection of dissolved acetylene in transformer oil in the mid infrared (MIR) wavelength (3021 nm) region. PMID:28218304

  14. Laser Calorimetry Spectroscopy for ppm-level Dissolved Gas Detection and Analysis

    NASA Astrophysics Data System (ADS)

    K. S., Nagapriya; Sinha, Shashank; Prashanth, R.; Poonacha, Samhitha; Chaudhry, Gunaranjan; Bhattacharya, Anandaroop; Choudhury, Niloy; Mahalik, Saroj; Maity, Sandip

    2017-02-01

    In this paper we report a newly developed technique – laser calorimetry spectroscopy (LCS), which is a combination of laser absorption spectroscopy and calorimetry - for the detection of gases dissolved in liquids. The technique involves determination of concentration of a dissolved gas by irradiating the liquid with light of a wavelength where the gas absorbs, and measuring the temperature change caused by the absorbance. Conventionally, detection of dissolved gases with sufficient sensitivity and specificity was done by first extracting the gases from the liquid and then analyzing the gases using techniques such as gas chromatography. Using LCS, we have been able to detect ppm levels of dissolved gases without extracting them from the liquid. In this paper, we show the detection of dissolved acetylene in transformer oil in the mid infrared (MIR) wavelength (3021 nm) region.

  15. Determination of the catalytic activity of binuclear metallohydrolases using isothermal titration calorimetry.

    PubMed

    Pedroso, Marcelo M; Ely, Fernanda; Lonhienne, Thierry; Gahan, Lawrence R; Ollis, David L; Guddat, Luke W; Schenk, Gerhard

    2014-03-01

    Binuclear metallohydrolases are a large and diverse family of enzymes that are involved in numerous metabolic functions. An increasing number of members find applications as drug targets or in processes such as bioremediation. It is thus essential to have an assay available that allows the rapid and reliable determination of relevant catalytic parameters (k cat, K m, and k cat/K m). Continuous spectroscopic assays are frequently only possible by using synthetic (i.e., nonbiological) substrates that possess a suitable chromophoric marker (e.g., nitrophenol). Isothermal titration calorimetry, in contrast, affords a rapid assay independent of the chromophoric properties of the substrate-the heat associated with the hydrolytic reaction can be directly related to catalytic properties. Here, we demonstrate the efficiency of the method on several selected examples of this family of enzymes and show that, in general, the catalytic parameters obtained by isothermal titration calorimetry are in good agreement with those obtained from spectroscopic assays.

  16. VO2sim 0.1: Using Simulation to Understand Measurement Error in Indirect Calorimetry

    DTIC Science & Technology

    2015-08-01

    illness. The Army has recognized the importance of understanding oxygen consumption in the field and is developing models to aid in operational decision...acclimatize to high altitude (Amann et al. 2013) and hypoxia (Self et al. 2013). The Army has recognized the importance of understanding oxygen consumption...Atwater and Benedict 1983). The cumbersome direct calorimetry method was later updated so that volumes of expired oxygen (VO2) and carbon dioxide

  17. Combined laser calorimetry and photothermal technique for absorption measurement of optical coatings

    SciTech Connect

    Li Bincheng; Blaschke, Holger; Ristau, Detlev

    2006-08-10

    To the best of our knowledge, a combined sensitive technique employing both laser calorimetry and a surface thermal lens scheme for measuring absorption values of optical coatings is presented for the first time. Laser calorimetric and pulsed surface thermal lens signals are simultaneously obtained with a highly reflecting UV coating sample irradiated at 193 nm. The advantages and potential applications of the combined technique and the experimental factors limiting the measurement sensitivity are discussed.

  18. Combined laser calorimetry and photothermal technique for absorption measurement of optical coatings.

    PubMed

    Li, Bincheng; Blaschke, Holger; Ristau, Detlev

    2006-08-10

    To the best of our knowledge, a combined sensitive technique employing both laser calorimetry and a surface thermal lens scheme for measuring absorption values of optical coatings is presented for the first time. Laser calorimetric and pulsed surface thermal lens signals are simultaneously obtained with a highly reflecting UV coating sample irradiated at 193 nm. The advantages and potential applications of the combined technique and the experimental factors limiting the measurement sensitivity are discussed.

  19. Absolute dosimetry on a dynamically scanned sample for synchrotron radiotherapy using graphite calorimetry and ionization chambers

    NASA Astrophysics Data System (ADS)

    Lye, J. E.; Harty, P. D.; Butler, D. J.; Crosbie, J. C.; Livingstone, J.; Poole, C. M.; Ramanathan, G.; Wright, T.; Stevenson, A. W.

    2016-06-01

    The absolute dose delivered to a dynamically scanned sample in the Imaging and Medical Beamline (IMBL) on the Australian Synchrotron was measured with a graphite calorimeter anticipated to be established as a primary standard for synchrotron dosimetry. The calorimetry was compared to measurements using a free-air chamber (FAC), a PTW 31 014 Pinpoint ionization chamber, and a PTW 34 001 Roos ionization chamber. The IMBL beam height is limited to approximately 2 mm. To produce clinically useful beams of a few centimetres the beam must be scanned in the vertical direction. In practice it is the patient/detector that is scanned and the scanning velocity defines the dose that is delivered. The calorimeter, FAC, and Roos chamber measure the dose area product which is then converted to central axis dose with the scanned beam area derived from Monte Carlo (MC) simulations and film measurements. The Pinpoint chamber measures the central axis dose directly and does not require beam area measurements. The calorimeter and FAC measure dose from first principles. The calorimetry requires conversion of the measured absorbed dose to graphite to absorbed dose to water using MC calculations with the EGSnrc code. Air kerma measurements from the free air chamber were converted to absorbed dose to water using the AAPM TG-61 protocol. The two ionization chambers are secondary standards requiring calibration with kilovoltage x-ray tubes. The Roos and Pinpoint chambers were calibrated against the Australian primary standard for air kerma at the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA). Agreement of order 2% or better was obtained between the calorimetry and ionization chambers. The FAC measured a dose 3-5% higher than the calorimetry, within the stated uncertainties.

  20. Absolute dosimetry on a dynamically scanned sample for synchrotron radiotherapy using graphite calorimetry and ionization chambers.

    PubMed

    Lye, J E; Harty, P D; Butler, D J; Crosbie, J C; Livingstone, J; Poole, C M; Ramanathan, G; Wright, T; Stevenson, A W

    2016-06-07

    The absolute dose delivered to a dynamically scanned sample in the Imaging and Medical Beamline (IMBL) on the Australian Synchrotron was measured with a graphite calorimeter anticipated to be established as a primary standard for synchrotron dosimetry. The calorimetry was compared to measurements using a free-air chamber (FAC), a PTW 31 014 Pinpoint ionization chamber, and a PTW 34 001 Roos ionization chamber. The IMBL beam height is limited to approximately 2 mm. To produce clinically useful beams of a few centimetres the beam must be scanned in the vertical direction. In practice it is the patient/detector that is scanned and the scanning velocity defines the dose that is delivered. The calorimeter, FAC, and Roos chamber measure the dose area product which is then converted to central axis dose with the scanned beam area derived from Monte Carlo (MC) simulations and film measurements. The Pinpoint chamber measures the central axis dose directly and does not require beam area measurements. The calorimeter and FAC measure dose from first principles. The calorimetry requires conversion of the measured absorbed dose to graphite to absorbed dose to water using MC calculations with the EGSnrc code. Air kerma measurements from the free air chamber were converted to absorbed dose to water using the AAPM TG-61 protocol. The two ionization chambers are secondary standards requiring calibration with kilovoltage x-ray tubes. The Roos and Pinpoint chambers were calibrated against the Australian primary standard for air kerma at the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA). Agreement of order 2% or better was obtained between the calorimetry and ionization chambers. The FAC measured a dose 3-5% higher than the calorimetry, within the stated uncertainties.

  1. Graphite calorimetry for absorbed dose measurements in heavy-ion beams

    NASA Astrophysics Data System (ADS)

    Sakama, M.; Kanai, T.; Fukumura, A.

    In order to sophisticate the radiotherapy high accuracy knowledge of the absorbed dose delivered to the patient is essential The main methods of absolute dosimetry are indicated as follows a Dosimetry by ion chamber b Fricke dosimetry and c Calorimetry The calorimetry is most direct method of dosimetry due to direct measurement of energy deposit in principle and no requirement of information of radiation fields for the calibration Many countries tend to adopt the calorimetry to determine the standard absorbed dose to water and become to be capable of deciding the absorbed dose in precision of about 0 6 for photon and electron beams Despite the recent progress of particle therapy the parameters such as w-value and stopping power ratio for ionization chambers in the particles is not obtained accurately Therefore that causes uncertainty in determination of the absolute dose For this reason we developed a graphite calorimeter to obtain high precision absorbed dose and reduce the uncertainty for various beams When the absorbed dose of 1 Gy is irradiated to the sensitive volume the temperature rise is about 1 4 milliKelvins The performance require the resolution of plus or minus 7 micro Kelvins to measure it in precision of plus or minus 0 5 The stability within several micro Kelvins per minute is necessary to obtain measurable background The miniature glass bead thermistors were embedded in the sensitive volume to perform active control of temperature The resistance change of these thermistors is approximately 0 68 Ohms and 488 micro Ohms at

  2. 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.

  3. Temperature dependence of adsorption of PEGylated lysozyme and pure polyethylene glycol on a hydrophobic resin: comparison of isothermal titration calorimetry and van't Hoff data.

    PubMed

    Werner, Albert; Hackemann, Eva; Hasse, Hans

    2014-08-22

    The influence of temperature on the adsorption of PEGylated lysozyme and pure PEG on Toyopearl PPG-600M, a hydrophobic resin, is studied by batch equilibrium measurements and pulse response experiments. Differently PEGylated lysozymes are used for the studies, enabling a systematic variation of the solute properties. Either ammonium sulfate or sodium chloride are added. The enthalpy of adsorption is calculated from a van't Hoff analysis based on these data. It is also directly measured by Isothermal Titration Calorimetry. In the investigated temperature range from 5 °C to 35 °C adsorption is favored by higher temperatures and hence endothermic. The results of the van't Hoff analysis of the equilibrium and the pulse response data agree well. Discrepancies between enthalpies of adsorption obtained by calorimetry and van't Hoff analysis are found and discussed. We conclude that the most likely explanation is that thermodynamic equilibrium is not reached in the experiments even though they were carried out carefully and in the generally accepted way.

  4. X-linked dystonia parkinsonism syndrome (XDP, lubag): disease-specific sequence change DSC3 in TAF1/DYT3 affects genes in vesicular transport and dopamine metabolism.

    PubMed

    Herzfeld, Thilo; Nolte, Dagmar; Grznarova, Maria; Hofmann, Andrea; Schultze, Joachim L; Müller, Ulrich

    2013-03-01

    X-chromosomal dystonia parkinsonism syndrome (XDP, 'lubag') is associated with sequence changes within the TAF1/DYT3 multiple transcript system. Although most sequence changes are intronic, one, disease-specific single-nucleotide change 3 (DSC3), is located within an exon (d4). Transcribed exon d4 occurs as part of multiple splice variants. These variants include exons d3 and d4 spliced to exons of TAF1, and an independent transcript composed of exons d2-d4. Location of DSC3 in exon d4 and utilization of this exon in multiple splice variants suggest an important role of DSC3 in the XDP pathogenesis. To test this hypothesis, we transfected neuroblastoma cells with four expression constructs, including exons d2-d4 [d2-d4/wild-type (wt) and d2-d4/DSC3] and d3-d4 (d3-d4/wt and d3-d4/DSC3). Expression profiling revealed a dramatic effect of DSC3 on overall gene expression. Three hundred and sixty-two genes differed between cells containing d2-d4/wt and d2-d4/DSC3. Annotation clustering revealed enrichment of genes related to vesicular transport, dopamine metabolism, synapse function, Ca(2+) metabolism and oxidative stress. Two hundred and eleven genes were differentially expressed in d3-d4/wt versus d3-d4/DSC3. Annotation clustering highlighted genes in signal transduction and cell-cell interaction. The data show an important role of physiologically occurring transcript d2-d4 in normal brain function. Interference with this role by DSC3 is a likely pathological mechanism in XDP. Disturbance of dopamine function and of Ca(2+) metabolism can explain abnormal movement; loss of protection against reactive oxygen species may account for the neurodegenerative changes in XDP. Although d3-d4 also affect genes potentially related to neurodegenerative processes, their physiologic role as splice variants of TAF1 awaits further exploration.

  5. Azide derivatized anticancer agents of Vitamin K 3: X-ray structural, DSC, resonance spectral and API studies

    NASA Astrophysics Data System (ADS)

    Badave, Kirti; Patil, Yogesh; Gonnade, Rajesh; Srinivas, Darbha; Dasgupta, Rajan; Khan, Ayesha; Rane, Sandhya

    2011-12-01

    Compound 1 [1-imino (acetyl hydrazino)-Vitamin K 3], displays valence tautomerically related electronic isomers as Form I and Form II. Form I exhibits 2D packing fragment with 1D ribbon chains of N-H⋯O hydrogen bonds and shows EPR silent features. While Form II is EPR active and exhibits biradical nature with double quantum transitions at g = 2.0040. 1H NMR of compound 2, [1-imino (hydrazino carboxylate)-Vitamin K 3] and Form II exhibit π delocalization via resonance assisted H-bonding [RAHB] effect compared to Form I. Molecular interactions in Form I and II are visualized by DSC. The electronic structures of compounds 1 and 2 have been correlated to their API values by measuring anticancer activities, mitochondrial potentials and DNA shearing patterns. Form II and compound 2 indicate mitochondria mediated apoptosis (˜75% cell death) while Form I causes 35% cell death.

  6. A DSC study on crystalline LaRC TPI powder - A new version with higher initial molecular weight

    NASA Technical Reports Server (NTRS)

    Hou, Tan-Hung; Bai, Jia-Mo; St. Clair, Terry L.

    1987-01-01

    A new version of crystalline Langley Research Center Thermoplastic Polyimide (LaRC-TPI) imidized powder, which possesses a higher initial molecular weight (MW), has been prepared and characterized. The scheme used for cyclodehydration during the synthesis of this material is described. Evidence of a higher initial MW for the subject LaRC-TPI is supported by both measurements of the inherent viscosity and the DSC thermograms. An initial melting peak at 295 C is noted in the freshly-synthesized sample. The powder can be recrystallized at any elevated temperatures below 340 C, and a single crystalline endothemic peak is always observed after various thermal histories. The heat of fusion for the fresh sample, as represented by the area under the melting peak in the directional scanning calorimeter thermogram, is about 3.9 cal/gm. Comparisons of thermal properties for the subject material are made to those exhibited by the commercial LaRC-TPI powder.

  7. Kinetics of thermolysis of lanthanum nitrate with hexamethylenetetramine: Crystal structure, TG-DSC, impact and friction sensitivity studies, Part-96

    NASA Astrophysics Data System (ADS)

    Nibha; Baranwal, B. P.; Singh, Gurdip; Singh, C. P.; Daniliuc, Constantin G.; Soni, P. K.; Nath, Yogeshwar

    2014-11-01

    The development of high energetic materials includes process ability and the ability to attain insensitive munitions (IM). This paper investigates the preparation of lanthanum metal nitrate complex of hexamethylenetetramine in water at room temperature. This complex of molecular formulae [La (NO3)2(H2O)6] (2HMTA) (NO3-) (H2O) was characterized by X-ray crystallography. Thermal decomposition was investigated using TG, TG-DSC and ignition delay measurements. Kinetic analysis of isothermal TG data has been investigated using model fitting methods as well as model free isoconversional methods. The sensitivity measurements towards mechanical destructive stimuli such as impact and friction were carried out and the complex was found to be insensitive. In order to identify the end product of thermolysis, X-ray diffraction patterns of end product was carried out which proves the formation of La2O3.

  8. Regional and voxel-wise comparisons of blood flow measurements between dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) and arterial spin labeling (ASL) in brain tumors.

    PubMed

    White, Carissa M; Pope, Whitney B; Zaw, Taryar; Qiao, Joe; Naeini, Kourosh M; Lai, Albert; Nghiemphu, Phioanh L; Wang, J J; Cloughesy, Timothy F; Ellingson, Benjamin M

    2014-01-01

    The objective of the current study was to evaluate the regional and voxel-wise correlation between dynamic susceptibility contrast (DSC) and arterial spin labeling (ASL) perfusion magnetic resonance imaging (MRI) measurement of cerebral blood flow (CBF) in patients with brain tumors. Thirty patients with histologically verified brain tumors were evaluated in the current study. DSC-MRI was performed by first using a preload dose of gadolinium contrast, then collecting a dynamic image acquisition during a bolus of contrast, followed by posthoc contrast agent leakage correction. Pseudocontinuous ASL was collected using 30 pairs of tag and control acquisition using a 3-dimensional gradient-echo spin-echo (GRASE) acquisition. All images were registered to a high-resolution anatomical atlas. Average CBF measurements within regions of contrast-enhancement and T2 hyperintensity were evaluated between the two modalities. Additionally, voxel-wise correlation between CBF measurements obtained with DSC and ASL were assessed. Results demonstrated a positive linear correlation between DSC and ASL measurements of CBF when regional average values were compared; however, a statistically significant voxel-wise correlation was only observed in around 30-40% of patients. These results suggest DSC and ASL may provide regionally similar, but spatially different measurements of CBF.

  9. Inclusion complexes of cypermethrin and permethrin with monochlorotriazinyl-beta-cyclodextrin: a combined spectroscopy, TG/DSC and DFT study.

    PubMed

    Yao, Qi; You, Bin; Zhou, Shuli; Chen, Meng; Wang, Yujiao; Li, Wei

    2014-01-03

    The suitable size hydrophobic cavity and monochlorotriazinyl group as a reactive anchor make MCT-β-CD to be widely used in fabric finishing. In this paper, the inclusion complexes of monochlorotriazinyl-beta-cyclodextrin (MCT-β-CD) with cypermethrin (CYPERM) and permethrin (PERM) are synthesized and analyzed by TG/DSC, FT-IR and Raman spectroscopy. TG/DSC reveals that the decomposed temperatures of inclusion complexes are lower by 25-30 °C than that of physical mixtures. DFT calculations in conjunction with FT-IR and Raman spectral analyses are used to study the structures of MCT-β-CD and their inclusion complexes. Four isomers of trisubstituted MCT-β-CD are designed and DFT calculations reveal that 1,3,5-trisubstituted MCT-β-CD has the lowest energy and can be considered as main component of MCT-β-CD. The ground-state geometries, vibrational wavenumbers, IR and Raman intensities of MCT-β-CD and their inclusion complexes were calculated at B3LYP/6-31G (d) level of theory. Upon examining the optimized geometry of inclusion complex, we find that the CYPERM and PERM are inserted into the toroid of MCT-β-CD from the larger opening. The band at 1646 cm(-1) in IR and at 1668 cm(-1) in Raman spectrum reveals that monochloroazinyl group of MCT-β-CD exists in ketone form but not in anion form. The noticeable IR and Raman shift of phenyl reveals that these two benzene rings of CYPERM and PERM stays inside the cavity of MCT-β-CD and has weak interaction with MCT-β-CD. This spectroscopy conclusion is consistent with theoretical predicted structure.

  10. Native ESI Mass Spectrometry Can Help to Avoid Wrong Interpretations from Isothermal Titration Calorimetry in Difficult Situations.

    PubMed

    Wolff, Philippe; Da Veiga, Cyrielle; Ennifar, Eric; Bec, Guillaume; Guichard, Gilles; Burnouf, Dominique; Dumas, Philippe

    2017-02-01

    We studied by native ESI-MS the binding of various DNA-polymerase-derived peptides onto DNA-polymerase processivity rings from Escherichia coli, Pseudomonas aeruginosa, and Mycobacterium tuberculosis. These homodimeric rings present two equivalent specific binding sites, which leads to successive formation during a titration experiment of singly- and doubly occupied rings. By using the ESI-MS free-ring spectrum as a ruler, we derived by robust linear regression the fractions of the different ring species at each step of a titration experiment. These results led to accurate Kd values (from 0.03 to 0.5 μM) along with the probability of peptide loss due to gas phase dissociation (GPD). We show that this good quality is due to the increased information content of a titration experiment with a homodimer. Isothermal titration calorimetry (ITC) led with the same binding model to Kd(ITC) values systematically higher than their ESI-MS counterparts and, often, to poor fit of the ITC curves. A processing with two competing modes of binding on the same site requiring determination of two (Kd, ΔH) pairs greatly improved the fits and yielded a second Kd(ITC) close to Kd(ESI-MS). The striking features are: (1) ITC detected a minor binding mode (~20%) of 'low-affinity' that did not appear with ESI-MS; (2) the simplest processing of ITC data with only one (Kd, ΔH) pair led wrongly to the Kd of the low-affinity binding mode but to the ΔH of the high-affinity binding mode. Analogous misleading results might well exist in published data based on ITC experiments. Graphical Abstract ᅟ.

  11. Native ESI Mass Spectrometry Can Help to Avoid Wrong Interpretations from Isothermal Titration Calorimetry in Difficult Situations

    NASA Astrophysics Data System (ADS)

    Wolff, Philippe; Da Veiga, Cyrielle; Ennifar, Eric; Bec, Guillaume; Guichard, Gilles; Burnouf, Dominique; Dumas, Philippe

    2017-02-01

    We studied by native ESI-MS the binding of various DNA-polymerase-derived peptides onto DNA-polymerase processivity rings from Escherichia coli, Pseudomonas aeruginosa, and Mycobacterium tuberculosis. These homodimeric rings present two equivalent specific binding sites, which leads to successive formation during a titration experiment of singly- and doubly occupied rings. By using the ESI-MS free-ring spectrum as a ruler, we derived by robust linear regression the fractions of the different ring species at each step of a titration experiment. These results led to accurate Kd values (from 0.03 to 0.5 μM) along with the probability of peptide loss due to gas phase dissociation (GPD). We show that this good quality is due to the increased information content of a titration experiment with a homodimer. Isothermal titration calorimetry (ITC) led with the same binding model to Kd(ITC) values systematically higher than their ESI-MS counterparts and, often, to poor fit of the ITC curves. A processing with two competing modes of binding on the same site requiring determination of two (Kd, ΔH) pairs greatly improved the fits and yielded a second Kd(ITC) close to Kd(ESI-MS). The striking features are: (1) ITC detected a minor binding mode ( 20%) of `low-affinity' that did not appear with ESI-MS; (2) the simplest processing of ITC data with only one (Kd, ΔH) pair led wrongly to the Kd of the low-affinity binding mode but to the ΔH of the high-affinity binding mode. Analogous misleading results might well exist in published data based on ITC experiments.

  12. Differential Scanning Calorimetric (DSC) Analysis of Rotary Nickel-Titanium (NiTi) Endodontic File (RNEF)

    NASA Astrophysics Data System (ADS)

    Wu, Ray Chun Tung; Chung, C. Y.

    2012-12-01

    To determine the variation of A f along the axial length of rotary nickel-titanium endodontic files (RNEF). Three commercial brands of 4% taper RNEF: GTX (#20, 25 mm, Dentsply Tulsa Dental Specialties, Tulsa, OK, USA), K3 (#25, 25 mm) and TF (Twisted File #25, 27 mm) (Sybron Kerr, Orange, CA, USA) were cut into segments at 4 mm increment from the working tip. Regional specimens were measured for differential heat-flow over thermal cycling, generally with continuous heating or cooling (5 °C/min) and 5 min hold at set temperatures (start, finish temperatures): GTX: -55, 90 °C; K3: -55, 45 °C; TF: -55, 60 °C; using differential scanning calorimeter. This experiment demonstrated regional differences in A f along the axial length of GTX and K3 files. Similar variation was not obvious in the TF samples. A contributory effect of regional difference in strain-hardening due to grinding and machining during manufacturing is proposed.

  13. Interfacial Water at Protein Surfaces: Wide-Line NMR and DSC Characterization of Hydration in Ubiquitin Solutions

    PubMed Central

    Tompa, Kálmán; Bánki, Péter; Bokor, Mónika; Kamasa, Pawel; Lasanda, György; Tompa, Péter

    2009-01-01

    Wide-line 1H-NMR and differential scanning calorimetry measurements were done in aqueous solutions and on lyophilized samples of human ubiquitin between −70°C and +45°C. The measured properties (size, thermal evolution, and wide-line NMR spectra) of the protein-water interfacial region are substantially different in the double-distilled and buffered-water solutions of ubiquitin. The characteristic transition in water mobility is identified as the melting of the nonfreezing/hydrate water. The amount of water in the low-temperature mobile fraction is 0.4 g/g protein for the pure water solution. The amount of mobile water is higher and its temperature dependence more pronounced for the buffered solution. The specific heat of the nonfreezing/hydrate water was evaluated using combined differential scanning calorimetry and NMR data. Considering the interfacial region as an independent phase, the values obtained are 5.0–5.8 J·g−1·K−1, and the magnitudes are higher than that of pure/bulk water (4.2 J·g−1·K−1). This unexpected discrepancy can only be resolved in principle by assuming that hydrate water is in tight H-bond coupling with the protein matrix. The specific heat for the system composed of the protein molecule and its hydration water is 2.3 J·g−1·K−1. It could be concluded that the protein ubiquitin and its hydrate layer behave as a highly interconnected single phase in a thermodynamic sense. PMID:19348762

  14. Characterization of the kinetic and thermodynamic landscape of RNA folding using a novel application of isothermal titration calorimetry.

    PubMed

    Vander Meulen, Kirk A; Butcher, Samuel E

    2012-03-01

    A novel isothermal titration calorimetry (ITC) method was applied to investigate RNA helical packing driven by the GAAA tetraloop-receptor interaction in magnesium and potassium solutions. Both the kinetics and thermodynamics were obtained in individual ITC experiments, and analysis of the kinetic data over a range of temperatures provided Arrhenius activation energies (ΔH(‡)) and Eyring transition state entropies (ΔS(‡)). The resulting rich dataset reveals strongly contrasting kinetic and thermodynamic profiles for this RNA folding system when stabilized by potassium versus magnesium. In potassium, association is highly exothermic (ΔH(25°C) = -41.6 ± 1.2 kcal/mol in 150 mM KCl) and the transition state is enthalpically barrierless (ΔH(‡) = -0.6 ± 0.5). These parameters are significantly positively shifted in magnesium (ΔH(25°C) = -20.5 ± 2.1 kcal/mol, ΔH(‡) = 7.3 ± 2.2 kcal/mol in 0.5 mM MgCl(2)). Mixed salt solutions approximating physiological conditions exhibit an intermediate thermodynamic character. The cation-dependent thermodynamic landscape may reflect either a salt-dependent unbound receptor conformation, or alternatively and more generally, it may reflect a small per-cation enthalpic penalty associated with folding-coupled magnesium uptake.

  15. HypCal, a general-purpose computer program for the determination of standard reaction enthalpy and binding constant values by means of calorimetry.

    PubMed

    Arena, Giuseppe; Gans, Peter; Sgarlata, Carmelo

    2016-09-01

    The program HypCal has been developed to provide a means for the simultaneous determination, from data obtained by isothermal titration calorimetry, of both standard enthalpy of reaction and binding constant values. The chemical system is defined in terms of species of given stoichiometry rather than in terms of binding models (e.g., independent or cooperative). The program does not impose any limits on the complexity of the chemical systems that can be treated, including competing ligand systems. Many titration curves may be treated simultaneously. HypCal can also be used as a simulation program when designing experiments. The use of the program is illustrated with data obtained with nicotinic acid (niacin, pyridine-3 carboxylic acid). Preliminary experiments were used to establish the rather different titration conditions for the two sets of titration curves that are needed to determine the parameters for protonation of the carboxylate and amine groups.

  16. Ligand binding to one-dimensional lattice-like macromolecules: analysis of the McGhee-von Hippel theory implemented in isothermal titration calorimetry.

    PubMed

    Velázquez-Campoy, Adrián

    2006-01-01

    The theory developed by McGhee and von Hippel for ligand binding to a one-dimensional lattice-like macromolecule provides a closed analytical form in the Scatchard representation. The application of such theory has been complicated by two facts: (1) it has been practically reduced to binding techniques, such as equilibrium dialysis, in which the partition between bound and free concentrations of all reactant species are directly accessible and experimentally determined, but infrequently applied to other binding techniques, such as calorimetry or spectroscopy, in which the direct observable is a magnitude proportional to the advance of the binding reaction monitored along the titration experiment, and (2) Scatchard analysis, developed as a quantitative graphical method, is currently outdated and used only qualitatively because of its weaknesses, limitations, and deficiencies. However, a general exact method for applying such theory to titration techniques in a correct and precise manner, without any limitation, can be delineated. In this article, the theory of cooperative ligand binding to linear lattice-like macromolecules has been implemented in isothermal titration calorimetry for the first time. This technique provides a complete thermodynamic characterization of ligand binding, but it has been barely used properly for this type of system. The description, the analysis of the formalism, and practical guidelines are presented, with considerations for experimental design and data analysis.

  17. 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.

  18. 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.

  19. Characterization of the evolution of the volume fraction of precipitates in aged AlMgSiCu alloys using DSC technique

    SciTech Connect

    Esmaeili, Shahrzad . E-mail: shahrzad@mecheng1.uwaterloo.ca; Lloyd, David J.

    2005-11-15

    Differential scanning calorimetry is used to quantify the evolution of the volume fraction of precipitates during age hardening in AlMgSiCu alloys. The calorimetry tests are run on alloy samples after aging for various times at 180 deg. C and the change in the collective heat effects from the major precipitation and dissolution processes in each run are used to determine the precipitation state of the samples. The method is implemented on alloys with various thermal histories prior to artificial aging, including commercial pre-aging histories. The estimated values for the relative volume fraction of precipitates are compared with the results from a newly developed analytical method using isothermal calorimetry and a related quantitative transmission electron microscopy work. Excellent agreement is obtained between the results from various methods.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. Calorimetry in superfluid He II to measure losses in superconducting magnets

    SciTech Connect

    Caspi, S.

    1982-04-01

    A method using calorimetry to measure magnet losses in pressurized Helium II is described. The isothermal nature of He II is used in measuring the overall heat capacity of the system and the net refrigeration power. During the measurements, the refrigeration power is held fixed, and the system (400 liters) temperature is near 1.92 K. The calorimetric measurement was calibrated against known power inputs between 1 and 20 W. This technique can even measure heat loads higher than the available refrigeration. Results of loss measurement on two dipole magnets are reported.

  6. 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).

  7. 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.

  8. 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.

  9. 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.

  10. Thermal Analysis of Plastics

    ERIC Educational Resources Information Center

    D'Amico, Teresa; Donahue, Craig J.; Rais, Elizabeth A.

    2008-01-01

    This lab experiment illustrates the use of differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) in the measurement of polymer properties. A total of seven exercises are described. These are dry exercises: students interpret previously recorded scans. They do not perform the experiments. DSC was used to determine the…

  11. PREFACE: XIII International Conference on Calorimetry in High Energy Physics (CALOR 2008)

    NASA Astrophysics Data System (ADS)

    Livan, Michele

    2009-07-01

    The XIII International Conference on Calorimetry in High Energy Physics was held in Pavia, Italy, 26-30 May 2008, picking up the baton from the 2006 Conference in Chicago. The Conference took place in the unique environment of the Theresian Room of the University Library. The attendees were surrounded by over 40 000 books of general interest and culture, and had the opportunity to see precious volumes written by such people as Galileo, Volta and Faraday. The Workshop brought together more than 120 participants, including senior scientists as well as young physicists, confirming the central and ever-growing role of calorimeters in modern particle physics. The development of these detectors, as stressed by Professor Klaus Pretzl in his lectio magistralis, has made it possible to explore new frontiers in physics, and the present scenario is no exception to this rule. With the LHC experiments almost completely installed and ready to take data, the Conference was an ideal chance to review the status of the different projects, whose development has been followed and discussed throughout the entire Calor series, and to show that they are capable of meeting the design specifications. Other highlights were the performance and physics results of calorimeters installed in currently operating experiments. In the session on astrophysics and neutrinos, the contributions confirmed the key role of calorimeters in this sector and demonstrated their growing application even beyond the field of accelerator physics. Considerable time was devoted to the state-of-the-art techniques in the design and operation of the detectors, while the session on simulation addressed the importance of a thorough understanding of the shower development to meet the demanding requirements of present experiments. Finally, on the R&D side, the particle flow and dual read-out concepts confronted the challenges issued by the next generation of experiments. This complex material was reviewed in 83

  12. Spiral Perfusion Imaging With Consecutive Echoes (SPICE™) for the Simultaneous Mapping of DSC- and DCE-MRI Parameters in Brain Tumor Patients: Theory and Initial Feasibility.

    PubMed

    Paulson, Eric S; Prah, Douglas E; Schmainda, Kathleen M

    2016-12-01

    Dynamic contrast-enhanced (DCE) and dynamic susceptibility contrast (DSC) magnetic resonance imaging (MRI) are the perfusion imaging techniques most frequently used to probe the angiogenic character of brain neoplasms. With these methods, T1- and T2/T2*-weighted imaging sequences are used to image the distribution of gadolinium (Gd)-based contrast agents. However, it is well known that Gd exhibits combined T1, T2, and T2* shortening effects in tissue, and therefore, the results of both DCE- and DSC-MRI can be confounded by these opposing effects. In particular, residual susceptibility effects compete with T1 shortening, which can confound DCE-MRI parameters, whereas dipolar T1 and T2 leakage and residual susceptibility effects can confound DSC-MRI parameters. We introduce here a novel perfusion imaging acquisition and postprocessing method termed Spiral Perfusion Imaging with Consecutive Echoes (SPICE) that can be used to simultaneously acquire DCE- and DSC-MRI data, which requires only a single dose of the Gd contrast agent, does not require the collection of a precontrast T1 map for DCE-MRI processing, and eliminates the confounding contrast agent effects due to contrast extravasation. A detailed mathematical description of SPICE is provided here along with a demonstration of its utility in patients with high-grade glioma.

  13. Spiral Perfusion Imaging With Consecutive Echoes (SPICE™) for the Simultaneous Mapping of DSC- and DCE-MRI Parameters in Brain Tumor Patients: Theory and Initial Feasibility

    PubMed Central

    Paulson, Eric S.; Prah, Douglas E.; Schmainda, Kathleen M.

    2017-01-01

    Dynamic contrast-enhanced (DCE) and dynamic susceptibility contrast (DSC) magnetic resonance imaging (MRI) are the perfusion imaging techniques most frequently used to probe the angiogenic character of brain neoplasms. With these methods, T1- and T2/T2*-weighted imaging sequences are used to image the distribution of gadolinium (Gd)-based contrast agents. However, it is well known that Gd exhibits combined T1, T2, and T2* shortening effects in tissue, and therefore, the results of both DCE- and DSC-MRI can be confounded by these opposing effects. In particular, residual susceptibility effects compete with T1 shortening, which can confound DCE-MRI parameters, whereas dipolar T1 and T2 leakage and residual susceptibility effects can confound DSC-MRI parameters. We introduce here a novel perfusion imaging acquisition and postprocessing method termed Spiral Perfusion Imaging with Consecutive Echoes (SPICE) that can be used to simultaneously acquire DCE- and DSC-MRI data, which requires only a single dose of the Gd contrast agent, does not require the collection of a precontrast T1 map for DCE-MRI processing, and eliminates the confounding contrast agent effects due to contrast extravasation. A detailed mathematical description of SPICE is provided here along with a demonstration of its utility in patients with high-grade glioma. PMID:28090589

  14. Comparison of first pass bolus AIFs extracted from sequential 18F-FDG PET and DSC-MRI of mice

    NASA Astrophysics Data System (ADS)

    Evans, Eleanor; Sawiak, Stephen J.; Ward, Alexander O.; Buonincontri, Guido; Hawkes, Robert C.; Adrian Carpenter, T.

    2014-01-01

    Accurate kinetic modelling of in vivo physiological function using positron emission tomography (PET) requires determination of the tracer time-activity curve in plasma, known as the arterial input function (AIF). The AIF is usually determined by invasive blood sampling methods, which are prohibitive in murine studies due to low total blood volumes. Extracting AIFs from PET images is also challenging due to large partial volume effects (PVE). We hypothesise that in combined PET with magnetic resonance imaging (PET/MR), a co-injected bolus of MR contrast agent and PET ligand can be tracked using fast MR acquisitions. This protocol would allow extraction of a MR AIF from MR contrast agent concentration-time curves, at higher spatial and temporal resolution than an image-derived PET AIF. A conversion factor could then be applied to the MR AIF for use in PET kinetic analysis. This work has compared AIFs obtained from sequential DSC-MRI and PET with separate injections of gadolinium contrast agent and 18F-FDG respectively to ascertain the technique‧s validity. An automated voxel selection algorithm was employed to improve MR AIF reproducibility. We found that MR and PET AIFs displayed similar character in the first pass, confirmed by gamma variate fits (p<0.02). MR AIFs displayed reduced PVE compared to PET AIFs, indicating their potential use in PET/MR studies.

  15. Assessing tumor cytoarchitecture using multi-echo DSC-MRI derived measures of the Transverse Relaxivity at Tracer Equilibrium (TRATE)

    PubMed Central

    Semmineh, Natenael B; Xu, Junzhong; Skinner, Jack T; Xie, Jingping; Li, Hua; Ayers, Gregory; Quarles, C Chad

    2014-01-01

    Purpose In brain tumor dynamic susceptibility contrast (DSC)-MRI studies, multi-echo acquisition methods are used to quantify the dynamic changes in T1 and T2* that occur when contrast agent (CA) extravasates. Such methods also enable the estimation of the effective tissue CA transverse relaxivity. The goal of this study was to evaluate the sensitivity of the Transverse Relaxivity at Tracer Equilibrium (TRATE) to tumor cytoarchitecture. Theory and Methods Computational and in vitro studies were used to evaluate the biophysical basis of TRATE. In 9L, C6 and human brain tumors, TRATE, the apparent diffusion coefficient (ADC), the CA transfer constant (Ktrans), the extravascular extracellular volume fraction (ve) and histological data were compared. Results Simulations and in vitro results indicate that TRATE is highly sensitive to variations in cellular properties such as cell size and density. The histologic cell density and TRATE values were significantly higher in 9L tumors as compared to C6 tumors. In animal and human tumors, a voxel-wise comparison of TRATE with ADC, ve, and Ktrans maps showed low spatial correlation. Conclusion The assessment of TRATE is clinically feasible and its sensitivity to tissue cytoarchitectural features not present in other imaging methods indicate that it could potentially serve as a unique structural signature or “trait” of cancer. PMID:25227668

  16. Poly(ethylene oxide) irradiated in the solid state, melt and aqueous solution—a DSC and WAXD study

    NASA Astrophysics Data System (ADS)

    Jurkin, Tanja; Pucić, Irina

    2012-09-01

    Interactions of the aggregate state of poly(ethylene oxide), PEO, and γ-irradiation conditions (total dose, atmosphere) on its thermal and crystalline properties were investigated by DSC and WAXD taking into account sample molecular mass and form. In PEO irradiated in the solid state and in the presence of oxygen, chain scission dominated over concurrent crosslinking up to 200 kGy, particularly in PEO powders, due to a large surface being in contact with air. In solid samples the degree of crystallinity and crystallite size increased with the dose up to 50 kGy, probably not just due to partial crystallization upon degradation of amorphous phase, but to recrystallization of broken tie molecules. The least changes in crystallinity and phase transformation temperatures occurred in solid films. A substantial decrease in crystallinity and transformation temperatures without the initial crystallinity increase was achieved in samples that were amorphous on irradiation, at temperatures above the PEO melting temperature and in aqueous solutions. Radiation crosslinking of the PEO aqueous solution in an inert atmosphere is the most suitable way to obtain a lower degree of crystallinity and phase transformation temperatures while preserving mechanical properties.

  17. Interaction of poly(L-lysines) with negatively charged membranes: an FT-IR and DSC study.

    PubMed

    Schwieger, Christian; Blume, Alfred

    2007-04-01

    The influence of the binding of poly(L-lysine) (PLL) to negatively charged membranes containing phosphatidylglycerols (PG) was studied by DSC and FT-IR spectroscopy. We found a general increase in the main transition temperature as well as increase in hydrophobic order of the membrane upon PLL binding. Furthermore we observed stronger binding of hydration water to the lipid head groups after PLL binding. The secondary structure of the PLL after binding was studied by FT-IR spectroscopy. We found that PLL binds in an alpha-helical conformation to negatively charged DPPG membranes or membranes with DPPG-rich domains. Moreover we proved that PLL binding induces domain formation in the gel state of mixed DPPC/DPPG or DMPC/DPPG membranes as well as lipid remixing in the liquid-crystalline state. We studied these effects as a function of PLL chain length and found a significant dependence of the secondary structure, phase transition temperature and domain formation capacity on PLL chain length and also a correlation between the peptide secondary structure and the phase transition temperature of the membrane. We present a system in which the membrane phase transition triggers a highly cooperative secondary structure transition of the membrane-bound peptide from alpha-helix to random coil.

  18. Effect of chirality on PVP/drug interaction within binary physical mixtures of ibuprofen, ketoprofen, and naproxen: a DSC study.

    PubMed

    Ivanov, Ivan T; Tsokeva, Zhivka

    2009-08-01

    We report on the thermal behavior of freshly prepared binary drug/polymer physical mixtures that contained ibuprofen, ketoprofen, or naproxen as a drug, and polyvinylpyrrolidone (PVP), hydroxyethylcellulose (HEC), or methylcellulose (MC) as excipient. At 6-10 degrees C/min heating rates the DSC detected a sharp, single endotherm that corresponds to the melting of drug. On heating physical mixtures of PVP and racemic ibuprofen or ketoprofen at lower heating rates, another endotherm was registered in front of the original one. To observe the additional endotherm, specific minimal values of the heating rate and of PVP weight fraction were needed; for ibuprofen and ketoprofen they were 1.5 and 2.0 degrees C/min, and 5 and 15% (w/w), respectively. At greater PVP weight fractions the top temperatures, T(mp), of both peaks were reduced almost linearly indicating strong solid-state interfacial reaction between the drug particles and PVP matrix. The additional endotherm was abolished at greater heating rates (2 degrees C/min for ibuprofen, 3 degrees C/min for ketoprofen), by replacing the racemate with respective S+-enantiomer and by replacing PVP with HEC and MC. Hence, the possible inclusion of enantioselective component within the PVP/drug interaction, responsible for the amorphization of physical mixture over storage, is assumed.

  19. Calorimetry Sample Exchange analysis of data report for October--December, 1988

    SciTech Connect

    Lyons, J.E.

    1989-12-31

    The goals of the Calorimetry Sample Exchange Program are to: discuss measurement differences; review and improve analytical measurements and methods; discuss new measurement capabilities; provide data to DOE on measurement capabilities to evaluate shipper-receiver differences; provide characterized or standard materials as necessary for exchange participants; and 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 sample or from data previously reported by that facility. This information is presented, in the form of a quarterly report, 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 bee collected to the same precision or for the same time periods. The six participating laboratories are Lawrence Livermore, Los Alamos, MRC-Mound, Westinghouse Hanford, Rocky Flats, and Savannah River.

  20. 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.