Sample records for calorimetry dsc experiments

  1. Thermodynamic properties of diosgenin determined by oxygen-bomb calorimetry and DSC

    NASA Astrophysics Data System (ADS)

    Zhao, Ming-Rui; Wang, Hong-Jie; Wang, Shu-Yu; Yue, Xiao-Xin

    2014-12-01

    The combustion enthalpy of diosgenin was determined by oxygen-bomb calorimetry. The standard mole combustion enthalpy and the standard mole formation enthalpy have been calculated to be -16098.68 and -528.52 kJ mol-1, respectively. Fusion enthalpy and melting temperature for diosgenin were also measured to be -34.43 kJ mol-1 and 212.33°C, respectively, according to differential scanning calorimetry (DSC) data. These studies can provide useful thermodynamic data for this compound.

  2. Evaluation of peritoneal tissue by means of differential scanning calorimetry (DSC).

    PubMed

    Torres, Kamil; Tr?bacz, Hanna; Chro?cicki, Andrzej; Pietrzyk, Lukasz; Torres, Anna

    2011-01-01

    Abdominal surgeries alter the integrity of the peritoneal layer and cause imbalances among immunological, inflammatory and angiogenic mechanisms within the tissue. During laparoscopic procedures a protective function of the peritoneal layer can be disturbed by the gas used to create a pneumoperitoneum. The aim of this study was to characterize peritoneal tissue by means of differential scanning calorimetry (DSC) as a reference for future investigations on the influence of surgical procedures on the physicochemical state of the peritoneum. Thirty-seven patients participated in the study. Patients were divided into three groups according to the type of surgery: group H - patients who underwent hernia repair; group Ch - patients who underwent laparoscopic cholecystectomy; and group C - patients operated due to rectal cancer. It was observed that onset temperature (T(o)), denaturation temperature (T(m)) and change of enthalpy (?H) during thermal denaturation of peritoneal collagen in were significantly different for these three groups of patients. The mean values of onset temperature (T(o)) and denaturation temperature (T(m)) in group H were significantly lower, while DH in this group was significantly higher than in the two other groups (Ch and C). This preliminary study does not answer whether the differences in collagen denaturation found in peritoneal tissue from different groups of patients resulted from a different inherent state of the tissue, or from surgical procedures. However, the results suggest that DSC is an appropriate method to study subtle changes in the physicochemical condition of the peritoneum using small samples obtained during surgical procedures. PMID:22252767

  3. Cure Kinetics Study of Two Epoxy Systems with Fourier Tranform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC)

    Microsoft Academic Search

    Dimitris S. Achilias; Maria M. Karabela; Eleni A. Varkopoulou; Irini D. Sideridou

    2012-01-01

    This work was aimed at the study of cure kinetics of two commercial thermosetting epoxy systems, Epikote resin 816 LV\\/Epikure F205 and Epikote resin 240\\/Epikure F205, by Fourier Tranform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC). The studied systems consist of a resin (A), based on a diglycidyl ether of bisphenol A and a hardener (B) based on the

  4. Differential scanning calorimetry (DSC) studies on the thermal properties of peanut proteins.

    PubMed

    Colombo, Andrés; Ribotta, Pablo Daniel; León, Alberto Edel

    2010-04-14

    Studies related to the functional and thermal properties of peanut proteins are limited if compared with other vegetable protein sources. The aim of this work was to study the thermal denaturation of peanut protein isolates (PPI) by DSC. The thermal profile of PPI showed two endothermic peaks (assigned to denaturation of arachin and conarachin fractions). The thermal stability of arachin and conarachin increased when water content decreased, and a critical water level was found for both fractions. The effect of protein denaturants was studied. Low contents of urea stabilized protein fractions, but lower T(d) values were found with increasing concentrations. DeltaH values of arachin were affected by urea. SDS affected DeltaH values and thermal stability of conarachin; the arachin fraction showed higher resistance to SDS-induced denaturation. DTT addition did not affect conarachin stability, although enthalpy values decreased significantly. On the other hand, arachin was greatly affected by DTT. In summary, thermal denaturation parameters of PPI were sensitive to water content, indicating that polar groups of arachin and conarachin contribute to structure stabilization. Urea addition mainly affected the structure of the arachin fraction, which was attributed to its higher surface hydrophobicity. Results obtained from SDS and DTT suggest that hydrophobic interactions and disulfide bonds play an important role in structure maintenance of arachin and conarachin. PMID:20222749

  5. Interdomain interactions in the chimeric protein toxin sCD4(178)-PE40: a differential scanning calorimetry (DSC) study.

    PubMed

    Davio, S R; Kienle, K M; Collins, B E

    1995-05-01

    The thermal denaturation of the chimeric protein toxin known as sCD4(178)-PE40 (sCD4-PE40) was studied using differential scanning calorimetry (DSC). sCD4-PE40 consists of HIV-binding domains of the T-cell membrane protein known as CD4 and the cytotoxic domains of Pseudomonas exotoxin A (PE40). sCD4-PE40 undergoes two DSC transitions. An endothermic transition associated with unfolding of the CD4 and PE40 components occurs at approximately 46 degrees C in buffered saline at pH 6.5. An exothermic transition associated with precipitation of unfolded protein occurs at higher temperatures. Both transitions are irreversible. DSC studies of solutions of pH 5.0 to 9.5 indicate that sCD4-PE40 shows maximal thermal stability at around pH 6.5. Variable pH experiments are also presented on solutions of sCD4(183) and PE40 revealing how these components denature as independent structural entities. sCD4(183) denaturation occurs at significantly higher temperatures than does the CD4 component of sCD4-PE40. PE40 denaturation occurs at the same temperatures as sCD4-PE40. These results suggest that the native CD4 and PE40 components are independent and non-interacting entities in the chimeric sCD4-PE40 molecule and that unfolding of the less-stable PE40 component induces unfolding of the CD4 component. These destabilizing interdomain interactions of sCD4-PE40 are in contrast to the stabilizing interactions which apparently exist in wild-type Pseudomonas exotoxin A between its PE40 domains and the cell binding domain of the native toxin (analogous to the CD4 component in sCD4-PE40). Reasons are discussed why the type of interdomain interactions observed for sCD4-PE40 might be the norm for chimeric proteins. PMID:7479546

  6. 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

  7. 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)

  8. Characterization of Two Different Clay Materials by Thermogravimetry (TG), Differential Scanning Calorimetry (DSC), Dilatometry (DIL) and Mass Spectrometry (MS) - 12215

    SciTech Connect

    Post, Ekkehard [NETZSCH Geraetebau GmbH, Wittelsbacherstrasse 42, 95100 Selb (Germany); Henderson, Jack B. [NETZSCH Instruments North America, LLC, 129 Middlesex Turnpike, Burlington, MA 01803 (United States)

    2012-07-01

    An illitic clay containing higher amounts of organic materials was investigated by dilatometry, thermogravimetry and differential scanning calorimetric. The evolved gases were studied during simultaneous TG-DSC (STA) and dilatometer measurements with simultaneous mass spectrometry in inert gas and oxidizing atmosphere. The dilatometer results were compared with the STA-MS results which confirmed and explained the reactions found during heating of the clay, like dehydration, dehydroxylation, shrinkage, sintering, quartz phase transition, combustion or pyrolysis of organics and the solid state reactions forming meta-kaolinite and mullite. The high amount of organic material effects in inert gas atmosphere most probably a reduction of the oxides which leads to a higher mass loss than in oxidizing atmosphere. Due to this reduction an additional CO{sub 2} emission at around 1000 deg. C was detected which did not occur in oxidizing atmosphere. Furthermore TG-MS results of a clay containing alkali nitrates show that during heating, in addition to water and CO{sub 2}, NO and NO{sub 2} are also evolved, leading to additional mass loss steps. These types of clays showed water loss starting around 100 deg. C or even earlier. This relative small mass loss affects only less shrinkage during the expansion of the sample. The dehydroxylation and the high crystalline quartz content result in considerable shrinkage and expansion of the clay. During the usual solid state reaction where the clay structure collapses, the remaining material finally shrinks down to a so-called clinker. With the help of MS the TG steps can be better interpreted as the evolved gases are identified. With the help of the MS it is possible to distinguish between CO{sub 2} and water (carbonate decomposition, oxidation of organics or dehydration/dehydroxylation). The MS also clearly shows that mass number 44 is found during the TG step of the illitic clay at about 900 deg. C in inert gas, which was interpreted as oxidation of pyrolytic carbon by reducing oxides. Additionally, without MS results, the mass loss steps of the nitrate contaminated clay could hardly be interpreted. (authors)

  9. DSC and DEA studies of underfill curing kinetics

    Microsoft Academic Search

    Yi He

    2001-01-01

    Isothermal and non-isothermal differential scanning calorimetry (DSC) and dielectric analysis (DEA) techniques were used to study the curing kinetics of an epoxy-based underfill material used in electronic packaging. Based on the phenomenological kinetic analyses, the activation energy for the curing reaction determined from the non-isothermal DSC studies is similar to that obtained from the isothermal DSC experiments. DEA and rheological

  10. Calorimetry for ILC Experiments: CALICE Collaboration R&D

    E-print Network

    D. S. Bailey; for the CALICE Collaboration

    2008-10-20

    The CALICE Collaboration is carrying out research and development into calorimetry for a detector at the International Linear Collider (ILC). CALICE is investigating a range of technologies for both electromagnetic and hadronic calorimetry. An overview of the prototypes and selected test-beam results are presented.

  11. 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…

  12. Bomb Calorimetry

    NSDL National Science Digital Library

    This site provides an animated overview (and actual performance) of a bomb calorimetry experiment. It would serve as a good introduction or review for students about to perform this experiment in the laboratory.

  13. Morphology characterization of emulsions by differential scanning calorimetry.

    PubMed

    Clausse, D; Gomez, F; Pezron, I; Komunjer, L; Dalmazzone, C

    2005-12-14

    This article is a review of some results obtained by Differential Scanning Calorimetry (DSC) for characterizing the morphology of emulsions. In a classical DSC experiment, an emulsion sample is submitted to a regular cooling and heating cycle between temperatures that include freezing and melting of the dispersed droplets. By using the thermograms found in the literature for various emulsions, how to get information about the solidification and melting, the presence of solute, the emulsion type, the transfer of matter, the stability and the droplet size is shown. PMID:16253203

  14. Initial calorimetry experiments in the Physics Division, ORNL (Oak Ridge National Laboratory)

    SciTech Connect

    Hutchinson, D.P.; Bennett, C.A.; Richards, R.K.; Bullock, J. IV.; Powell, G.L.

    1989-01-01

    Four calorimetry experiments were performed with palladium cathode electrolysis cells to investigate the possibility of cold fusion heat production based on the reported results of Fleischmann and Pons. Two of the cells contained 6.35-mm-diam {times} 10-cm-long palladium cathodes in a 0.2-M {sup 6}LiOD electrolyte; one cell contained a similar cathode in a 0.1-M {sup 6}LiOD electrolyte solution; and one cell used a cast 1.27-cm-diam {times} 10-cm long palladium rod in a 0.2-M electrolyte. All four cells were constructed with platinum wire anodes. One of the cells exhibited an apparent 2-3 W power excess for a period of approximately 300 hours of a total operating time of 1800 hours; each of the remaining cells remained in power balance for the 1800 hour period. 2 refs., 5 figs.

  15. DSC Study of Collagen in Disc Disease.

    PubMed

    Skrzy?ski, S; Sionkowska, A; Marciniak, A

    2009-01-01

    Differential scanning calorimetry (DSC) has been used to estimate the effect of disc disease on the collagen helix-coil transition and morphology for tissue extracted from patients during surgical operation. Forty discs were obtained from patients with degenerative disc disease undergoing surgery for low back pain. The patients were in the age between 20 and 70 years old. The specimens were kept wet during DSC experiment. The data allow the comparison between thermal stability of collagen tissue from healthy patients and from patients suffering from disc disease. In the paper the comparison between thermal helix-coil transition for collagen fibers from patients suffering from disc disease and collagen fibers from healthy organisms has been discussed. The heating rate has an influence on the position on denaturation temperatures of collagen in disc tissues. Higher helix-coil transition temperature of collagen in degenerated disc suggests that additional intermolecular cross linking of collagen fibers occurs. Denaturation temperatures of collagen in degenerated male disc possess smaller values than in female ones. Disc disease induces changes in collagen structure and leads to formation of additional crosslinks between collagen fibers. PMID:20169086

  16. 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 ?M>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 (?H) 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. PMID:25461813

  17. The Enthalpy of Decomposition of Hydrogen Peroxide: A General Chemistry Calorimetry Experiment

    NASA Astrophysics Data System (ADS)

    Marzzacco, Charles J.

    1999-11-01

    A calorimetry experiment involving the catalytic decomposition of aqueous hydrogen peroxide is presented. The experiment is simple, inexpensive, and colorful. In its simplest form, it can be performed in less than one hour; therefore, it is quite suitable for high school labs, which often have time restrictions. The chemicals required are household or commercial 3% H2O2(aq) and 0.50 M Fe(NO3)3(aq). Styrofoam cup calorimeters and thermometers with a range from 20 to 50 oC are also required. Ideally, the thermometers should be precise to 0.01 oC. The temperature of the H2O2 solution is monitored before and after the Fe(NO3)3 catalyst is added. The addition of the catalyst results in a color change and the evolution of heat and bubbles of oxygen. At the conclusion of the reaction, the color of the reaction mixture returns to that of the original Fe(NO3)3 solution. The heat change for the reaction is determined from the temperature change, the specific heat of the solution, and the calorimeter constant. The experimental enthalpy change for the reaction is in excellent agreement with the literature value.

  18. Isothermal titration calorimetry and differential scanning calorimetry as complementary tools to investigate the energetics of biomolecular recognition

    Microsoft Academic Search

    Ilian Jelesarov; Hans Rudolf Bosshard

    1999-01-01

    The principles of isothermal titration calorimetry (ITC) and differential scanning calorimetry (DSC) are reviewed together with the basic thermodynamic formalism on which the two techniques are based. Although ITC is particularly suitable to follow the energetics of an association reaction between biomolecules, the combination of ITC and DSC provides a more comprehensive description of the thermodynamics of an associating system.

  19. Autocatalytic cure kinetics from isothermal DSC measurements

    SciTech Connect

    Keenan, M.R.

    1986-06-01

    Isothermal differential scanning calorimetry (DSC) can be used to characterize the cure kinetics of thermosetting polymers. Expressions relating autocatalytic rate law parameters to characteristic features of the DSC cure exotherm are developed. The simultaneous solution of these equations provides a simple method for estimating the rate law from isothermal DSC measurements. This technique does not require nonlinear least squares fitting, but rather, relies solely upon characteristics of the exotherm such as the peak reaction rate, time to the peak and extent of cure at the peak. The method is illustrated by obtaining the cure kinetics of an epoxy film adhesive (American Cyanamid FM 123-5) and a silicone encapsulating resin (Dow Corning Sylgard 184). The resulting rate laws are shown to describe the DSC exotherms in their entirety. The predictive ability of the rate law is also examined for the epoxy system and found to be good.

  20. Comparison of Normal and in vitro Aging by NonEnzymatic Glycation as Verified by Differential Scanning Calorimetry

    Microsoft Academic Search

    R. Reihsner; W. Pfeiler; E. J. Menzel

    1998-01-01

    The biomechanical parameters of rat tail tendons (RTTs) from 35-, 64-, 180- and 900-day-old animals, corresponding to the early maturation phase, the mature and the senescent state were determined. The increase of maximum stiffness, ultimate stress and the elastic fraction of stress was most pronounced in the maturation phase. Differential scanning calorimetry (DSC) experiments were performed showing an almost linear

  1. Upscalingof dsc data of high energetic materials

    Microsoft Academic Search

    B. Roduit; Ch. Borgeat; B. Berger; P. Folly; H. Andres; U. Schädeli; B. Vogelsanger

    2006-01-01

    Differential scanning\\u000a calorimetry (DSC) carried out with few heating rates was applied in the studies\\u000a of the thermal properties of four energetic materials: EI propellant,\\u000a high explosive PBXW-17, pyrotechnic mixtures with composition B\\/KNO3\\u000a (50:50) and B\\/KNO3 (30:70). DSC signals, after optimization\\u000a of the baseline, were used for the calculation of the kinetic parameters (KP)\\u000a of the decomposition process applying advanced

  2. 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.

  3. Forensic characterization of HDPE pipes by DSC.

    PubMed

    Sajwan, Madhuri; Aggarwal, Saroj; Singh, R B

    2008-03-01

    The melting behavior of 28 high density polyethylene (HDPE) pipe samples manufactured and supplied by 13 different manufacturers in India was examined by 'differential scanning calorimetry (DSC)' to find out if this parameter could be used in differentiating between these HDPE pipe samples which are chemically the same and being manufactured by different manufacturer. The results indicate that the melting temperature may serve as the useful criteria for differentiating HDPE (i) pipe samples from different sources and (ii) samples of different diameter from the same source. PMID:17630240

  4. Gelatinization and retrogradation of 6-year-old korean ginseng starches studied by DSC

    Microsoft Academic Search

    Hye-Jin Koo; So-Hee Park; Jae-sun Jo; Byung-Yong Kim; Moo-Yeol Baik

    2005-01-01

    Gelatinization and retrogradation characteristics of 6-year-old Korean ginseng starch with different grades were investigated using differential scanning calorimetry (DSC). The 1st and 3rd grade ginseng starches showed typical biphasic DSC endotherm while 2nd grade ginseng starch revealed monophasic DSC endotherm with relatively narrow transition temperature. Although Avrami exponents (n) of all ginseng starches were close to 1.0 (i.e., retrogradation of

  5. Assessment of damage in old parchments by DSC and SEM

    Microsoft Academic Search

    G. Della Gatta; E. Badea; R. Ceccarelli; T. Usacheva; S. Coluccia

    2005-01-01

    Summary  Environmental impact on parchment was investigated by differential scanning calorimetry (DSC) and scanning electron microscopy\\u000a (SEM). Parchments subjected to accelerated ageing and old parchments were compared to evaluate quality and extent of deterioration.\\u000a Stability of fibrillar collagen within parchment was determined from the changes in thermodynamic parameters associated with\\u000a thermal denaturation. Parchment surface was characterised, and specific morphological criteria were

  6. PURITY AND HEAT OF FUSION DATA FOR ENVIRONMENTAL STANDARDS AS DETERMINED BY DIFFERENTIAL SCANNING CALORIMETRY

    EPA Science Inventory

    Differential scanning calorimetry (DSC) has been applied to 273 environmental standards, including pesticides, herbicides and related compounds. embers of the following chemical classes were analyzed: rganophosphorus, organochlorine, phenol, triazine, uracil, phenoxy acid, urea, ...

  7. DSC study of cure kinetics of DGEBA-based epoxy resin with poly(oxypropylene) diamine

    Microsoft Academic Search

    J. Macan; I. Brnardi?; M. Ivankovi?; H. J. Mencer

    2005-01-01

    Summary A kinetic study of cure kinetics of epoxy resin based on a diglycidyl ether of bisphenol A (DGEBA), with poly(oxypropylene) diamine (Jeffamine D230) as a curing agent, was performed by means of differential scanning calorimetry (DSC). Isothermal and dynamic DSC characterizations of stoichiometric and sub-stoichiometric mixtures were performed. The kinetics of cure was described successfully by empirical models in

  8. DSC studies of the curing mechanisms and kinetics of DGEBA using imidazole curing agents

    Microsoft Academic Search

    S. K. Ooi; W. D. Cook; G. P. Simon; C. H. Such

    2000-01-01

    The curing mechanisms and kinetics of diglycidyl ether of bisphenol A using 1-methylimidazole (1-MI), 2-methylimidazole (2-MI), 2-phenylimidazole (2-PhI) and 1,2-dimethylimidazole (1,2-DMI) as the curing agents were studied using scanning and isothermal differential scanning calorimetry (DSC). Both scanning and isothermal DSC studies indicated that only 1-MI was an effective curing agent, resulting in a high degree of conversion and high Tg,

  9. Curing kinetics of phase separating thermosets studied by DSC, TMDSC and dielectric relaxation spectroscopy

    Microsoft Academic Search

    I. Alig; W. Jenninger; J. E. K. Schawe

    1999-01-01

    Differential scanning calorimetry (DSC), temperature-modulated DSC (TMDSC) and dielectric relaxation spectroscopy have been performed during isothermal curing of an epoxy network (diglycidylether of bisphenol A cross-linked with diaminodiphenyl methane) and of thermoplast modified epoxy resins (“semi-interpenetrating polymer networks”) consisting of the epoxy network component and different amounts (10 and 20wt%) of a linear high Tg-polymer (polyethersulfone). During reaction the homogeneous

  10. A differential scanning calorimetry study of different lupin species meals

    Microsoft Academic Search

    Margarida M. Falcão-Rodrigues; Margarida Moldão-Martins; Luisa M. Beirão-da-Costa

    2002-01-01

    An investigation was conducted on the thermal behaviour of meals of six lupin species (L. albus, L. angustifolius, L. mutabilis, L. luteus, L. pilosus and L. hispanicus) by monitoring transition temperature, transition enthalpies and activation energy by differential scanning calorimetry (DSC). Results showed two thermal transitions in the meals of all the species at about 27 °C and 53 °C

  11. Effect of critical molecular weight of PEO in epoxy/EPO blends as characterized by advanced DSC and solid-state NMR

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoliang; Lu, Shoudong; Sun, Pingchuan; Xue, Gi

    2013-03-01

    The differential scanning calorimetry (DSC) and solid state NMR have been used to systematically study the length scale of the miscibility and local dynamics of the epoxy resin/poly(ethylene oxide) (ER/PEO) blends with different PEO molecular weight. By DSC, we found that the diffusion behavior of PEO with different Mw is an important factor in controlling these behaviors upon curing. We further employed two-dimensional 13C-{1H}PISEMA NMR experiment to elucidate the possible weak interaction and detailed local dynamics in ER/PEO blends. The CH2O group of PEO forms hydrogen bond with hydroxyl proton of cured-ER ether group, and its local dynamics frozen by such interaction. Our finding indicates that molecular weight (Mw) of PEO is a crucial factor in controlling the miscibility, chain dynamics and hydrogen bonding interaction in these blends.

  12. Thermal characterization of HCN polymers by TG–MS, TG, DTA and DSC methods

    Microsoft Academic Search

    José L. de la Fuente; Marta Ruiz-Bermejo; Susana Osuna-Esteban

    2011-01-01

    This paper presents a thermogravimetry (TG) study of hydrogen cyanide polymers, synthesized from the reaction of equimolar aqueous solutions of sodium cyanide and ammonium chloride. Differential thermal analysis (DTA) and differential scanning calorimetry (DSC) were also used to evaluate the thermal behaviour of these black polymers, which play an important role in prebiotic chemistry. A coupled TG–mass spectrometer (MS) system

  13. Thermal analysis on parchments I: DSC and TGA combined approach for heat damage assessment

    Microsoft Academic Search

    D. Fessas; M. Signorelli; A. Schiraldi; C. J. Kennedy; T. J. Wess; B. Hassel; K. Nielsen

    2006-01-01

    Ancient, new and artificially aged parchments were investigated with both differential scanning calorimetry (DSC) and thermogravimetry (TGA). Criteria to define a quantitative ranking of the damage experienced by the bulk collagen of historical parchments were assessed. A damage-related correlation was found between the collagen denaturation temperature and the moisture content of the parchment. Qualitative rules for the evaluation of the

  14. Changes in hydrothermal stability of leather and parchment with deterioration: a DSC study

    Microsoft Academic Search

    Claire Chahine

    2000-01-01

    Differential scanning calorimetry (DSC) allows to study the enthalpy changes which are associated with the denaturation of collagen, of which shrinkage is the macroscopic manifestation. Damage to skin, leather or parchment may be expected to manifest as a decrease of either the temperature of denaturation and\\/or the enthalpy changes. These modifications are associated with those of other chemical and mechanical

  15. Cure kinetics of epoxy resins studied by non-isothermal DSC data

    Microsoft Academic Search

    D Ro?u; C. N Ca?caval; F Musta; C Ciobanu

    2002-01-01

    The curing kinetics of diglycidyl ether of bisphenol A (DGEBA) and diglycidyl ether of hydroquinone (DGEHQ) epoxy resins in presence of diglycidyl aniline as a reactive diluent and triethylenetetramine (TETA) as the curing agent was studied by non-isothermal differential scanning calorimetry (DSC) technique at different heating rates. The kinetic parameters of the curing process were determined by isoconversional method given

  16. DSC analysis on water state of salvia hydrogels

    Microsoft Academic Search

    Rike Yudianti; Myrtha Karina; Masahiro Sakamoto; Jun-ichi Azuma

    2009-01-01

    The role of the water structure present in hydrogels from nutlets of three species of salvias,S. miltiorrhiza (SM),S. sclarea (SS) andS. viridis (SV), was analyzed by differential scanning calorimetry (DSC). The sharp endothermic peaks that appeared at 5.9 °C (SM),\\u000a 2.8 °C (SS) and 1.8 °C (SV) in each 1.0% hydrogel of 10.4–15.8% were not affected by addition of 0.1

  17. Phase Behavior of Poly(Ethylene Oxide) Studied by Modulated?Temperature DSC—Influence of the Molecular Weight

    Microsoft Academic Search

    Krzysztof Pielichowski; Kinga Flejtuch

    2005-01-01

    Melting and crystallization behavior of poly(ethylene oxide) (PEO) with different molecular weight was investigated by modulated?temperature differential scanning calorimetry (MT?DSC)—step?scan alternating DSC. It was found that by separating the reversing and nonreversing components of the (total) heat flow, PEO 10000, which exhibits the highest degree of crystallinity, shows the smallest nonreversing signal during crystallization. This effect can be attributed to

  18. PET recycled and processed from flakes with different amount of water uptake: characterization by DSC, TG, and FTIR-ATR

    Microsoft Academic Search

    Adhemar Ruvolo-Filho; Priscila S. Curti

    2008-01-01

    Recycled PET from bottles was processed from flakes, which containing different amounts of water uptake. After this process,\\u000a they are subjected to characterization by differential scanning calorimetry (DSC), thermogravimetry (TG), and Fourier-transform\\u000a infrared spectroscopy with an attenuated total reflectance accessory (FTIR-ATR). From the DSC and TG results it can be postulate\\u000a an increase in the proportion of short-molecular-weight distribution in

  19. Kinetics Characteristics of Nitrogen Hydrates Respond to Differential Scanning Calorimetry

    NASA Astrophysics Data System (ADS)

    Chen, Q.; Liu, C.; Ye, Y.; Gong, J.

    2012-12-01

    In this study, a high pressure differential scanning calorimetry (HP DSC) based on thermo-analytical technique was applied to investigate the kinetics and thermodynamics characteristics of nitrogen hydrates. Nitrogen hydrates was synthesized in the sample vessel under different pressures as temperature decreased from 293 to 233 K with a constant cooling rate of 0.2 K/min controlled by the DSC. To measure the hydrates dissociation enthalpies , the temperature was slowly raised up from 233 to 293 K at a constant rate ranging of 0.05 K/min. 1. Peak area on the heat flow curves represents the amount of heat during phase transition. In these experiments, the total water added to the sample vessel (mt) is already known. By integrating the peak areas of ice and hydrate, we know the total heats of ice (Qi) and hydrate (Qh), respectively. As the heat of ice per gram can be measured easily (336.366 J/g), the mass of ice (mi) can be obtain. Then, the dissociation heat of nitrogen hydrate per gram (Hh ) can be calculated by the equation: H(J/g)=Qh/(mt-mi) It is shown that the dissociation heats of nitrogen hydrates are a little larger than ice, but do not change a lot with different pressures. The average value of dissociation heat is 369.158 J/g. 2. During the DSC cooling stage, hydrate formed at temperature much lower than equilibrium. The biggest sub-cooling is about 291 K, while the smallest one is about 279 K. However, during these experiments, the pressure did not show obvious relationship with sub-cooling. It confirmed that even the proper conditions were achieved, formation was still a stochastic process. For one thing, due to the random distribution of dissolved gas in water, the interfacial tension and the water activity were not equal in the whole system. And if there was a free gas phase, which leads to different fugacity on water-gas interface, the stochastic behavior would be more significant in the sample vessel. 3. The energy released from hydrates formation as a function of time can be obtained by integrating the exothermic peaks. As a series of experiments were carried out using the same bulk phase, these curves represented a semi-quantitative result of hydrate crystal growth speed (see Figure 1). The slope of the energy curve reflected the growth speed at a certain time. The steeper the curve became, the faster the hydrates growth was. As could be expected, hydrate growth speed is extremely dependent of the sub-cooling.; Figure 1. Energy released of hydrates growth as a function of time

  20. Spectral calorimetry study of relaxation behavior of PMMA

    NASA Astrophysics Data System (ADS)

    Vassilev, Ts.; Avramov, I.; Velinov, Ts.; Surnev, S.

    1994-07-01

    The frequency dependence of the photoacoustic (PA) signal is investigated upon heating of poly(methyl methacrylate) (PMMA) in the glass transition region. The frequency ƒ vs reciprocal glass transition temperature Tg data, obtained from the present PA measurements, are compared with those of the previous differential scanning calorimetry (DSC) investigation. The results are in good agreement with the theoretical models of Avramov and Milchev and of Adam and Gibbs.

  1. NMR relaxometry and differential scanning calorimetry during meat cooking

    Microsoft Academic Search

    Hanne Christine Bertram; Zhiyun Wu; Frans van den Berg; Henrik J. Andersen

    2006-01-01

    By combining simultaneous nuclear magnetic resonance (NMR) T2 relaxometry and differential scanning calorimetry (DSC) on pork samples heated to nine temperature levels between 25 and 75°C, the present study investigates the relationship between thermal denaturation of meat proteins and heat-induced changes in water characteristics. Principal component analysis (PCA) on the distributed 1H NMR T2 relaxation data revealed that the major

  2. Differential scanning calorimetry study of hydrated ground granulated blast-furnace slag

    Microsoft Academic Search

    W. Sha; G. B. Pereira

    2001-01-01

    The present work involves using differential scanning calorimetry (DSC) in an investigation of the thermal behaviour of hydration products in ground granulated blast-furnace slag (ggbs). The two-step loss of water from calcium silicate hydrates and dehydroxylation of calcium hydroxide (Ca(OH)2) contribute, respectively, to the two major peaks in the DSC curves. Peaks due to the formation of ettringite and Fe2O3

  3. 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.

  4. USING VISIBLE AND NEAR-INFRARED REFLECTANCE SPECTROSCOPY AND DIFFERENTIAL SCANNING CALORIMETRY TO STUDY STARCH, PROTEIN, AND TEMPERATURE EFFECTS ON BREAD STALING

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Starch, protein, and temperature effects on bread staling were investigated using visible and near-infrared spectroscopy (NIRS) and differential scanning calorimetry (DSC). Bread staling was mainly due to amylopectin retrogradation. NIRS measured amylopectin retrogradation accurately in different ba...

  5. Melting and thermal history of poly(hydroxybutyrate-co-hydroxyvalerate) using step-scan DSC

    Microsoft Academic Search

    L. M. W. K. Gunaratne; R. A. Shanks

    2005-01-01

    Melting behaviour and crystal morphology of poly(3-hydroxybutyrate) (PHB) and its copolymer of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with various hydroxyvalerate (HV) contents [5wt.% (PHB5HV), 8wt.% (PHB8HV) and 12wt.% (PHB12HV)] have been investigated by conventional DSC, step-scan differential scanning calorimetry (SDSC) and hot-stage polarised optical microscopy (HSPOM). Crystallisation behaviour of PHB and its copolymers were investigated by SDSC. Thermal properties were investigated after different crystallisation

  6. Multiple melting behaviour of poly(3-hydroxybutyrate-co-hydroxyvalerate) using step-scan DSC

    Microsoft Academic Search

    L. M. W. K. Gunaratne; R. A. Shanks

    2005-01-01

    Melting behaviour and crystal morphology of poly(3-hydroxybutyrate) (PHB) and its copolymer of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with various hydroxyvalerate (HV) contents [5wt.% (PHB5V), 8wt.% (PHB8V) and 12wt.% (PHB12V)] have been investigated by conventional DSC, step-scan differential scanning calorimetry (SDSC), wide angle X-ray diffraction (WAXRD) and hot stage polarised optical microscopy (HSPOM). Crystallisation behaviour of PHB and its copolymers were investigated by isothermal crystallisation

  7. NMR, DSC and high pressure electrical conductivity studies of liquid and hybrid electrolytes

    Microsoft Academic Search

    P. E. Stallworth; J. J. Fontanella; M. C. Wintersgill; Christopher D. Scheidler; Jeffrey J. Immel; S. G. Greenbaum; A. S. Gozdz

    1999-01-01

    Electrical conductivity, differential scanning calorimetry (DSC) and 'Li nuclear magnetic resonance (NMR) studies have been carried out on liquid electrolytes such as ethylene carbonate:propylene carbonate (EC:PC) and ECdimethyl carbonate (DMC) containing LiPF, (and LiCFaSO, for NMR) and films plasticized using the same liquid electrolytes. The films are based on poly(vinylidene fluoride) (PVdF) copolymerized with hexafluoropropylene and contain fumed silica. All

  8. DSC study on the effect of isocyanates and catalysts on the HTPB cure reaction

    Microsoft Academic Search

    C. Korah Bina; K. G. Kannan; K. N. Ninan

    2004-01-01

    The urethane forming cure reactions of hydroxyl terminated polybutadiene (HTPB) binder with three different isocyanate curatives, viz., toluene diisocyanate (TDI), isophorone diisocyanate (IPDI) and 4,4'-methylene bis(cyclohexyl isocyanate) (MCHI), were investigated by differential scanning calorimetry (DSC). The effect of two cure catalysts, viz., dibutyl tin dilaurate (DBTDL) and ferrric tris-acetylacetonate (FeAA) on the cure reactions was also studied. Cure kinetics was

  9. A DSC Study on Cure Kinetics of HTPB-IPDI Urethane Reaction

    Microsoft Academic Search

    K. B. Catherine; K. Krishnan; K. N. Ninan

    2000-01-01

    The kinetics of theurethane-forming cure reaction of hydroxyl terminated polybutadiene (HTPB) with isophorone diisocyanate (IPDI) in presence of ferric tris (acetyl acetonate) (FeAA) catalyst was investigated using differential scanning calorimetry (DSC). The Arrhenius activation parameters, viz., activation energy E and pre-exponential factor A were evaluated using the non-isothermal integral Coats-Redfern equation. The cure reaction was catalysed by ferric acetyl acetonate

  10. Kinetics and hazards of thermal decomposition of methyl ethyl ketone peroxide by DSC

    Microsoft Academic Search

    Min-Hao Yuan; Chi-Min Shu; Arcady A. Kossoy

    2005-01-01

    Differential scanning calorimetry (DSC) was applied to analyze thermal decomposition of methyl ethyl ketone peroxide (MEKPO). Thermokinetic parameters and thermal stability were evaluated. MEKPO decomposes in at least three exothermic decomposition reactions and begins to decompose at 30–32°C. The total heat of decomposition is 1.26±0.03kJg?1. Thermal decomposition of MEKPO can be described by a model of two independent reactions: the

  11. NMR and DSC study of polymer electrolyte–Carbon Black composites

    Microsoft Academic Search

    R. W. A Franco; J. P Donoso; C. J Magon; J. M Pernaut; P. P de Souza

    2000-01-01

    Measurements of 1H nuclear magnetic resonance (NMR) and differential scanning calorimetry (DSC) are reported for the composite formed by poly(ethylene oxide) (PEO) and Carbon Black (CB) and the composite polymer electrolytes formed by PEO8LiClO4 and CB. The 1H NMR lineshapes and relaxation times (T1 and T2) were investigated as a function of temperature and CB concentration. The results suggest that

  12. Measuring the glass transition temperature of EPDM roofing materials: Comparison of DMA, TMA, and DSC techniques

    Microsoft Academic Search

    R. M. Paroli; J. Penn

    1994-01-01

    Two ethylene-propylene-diene monomer (EPDM) roofing membranes were aged at 100 C for 7 and 28 days. The T{sub g} of these membranes was then determined by dynamic mechanical analysis (DMA), thermomechanical analysis (TMA), and differential scanning calorimetry (DSC) and the results compared. It was found that: (1) T{sub g} data can be obtained easily using the DMA and TMA techniques.

  13. DSC study of precipitation processes in Cu-Co-Si alloys

    Microsoft Academic Search

    A. Varschavsky; E. Donoso

    2003-01-01

    Using differential scanning calorimetry (DSC) the precipitation processes of supersaturated solid solutions of three Cu-Co-Si\\u000a alloys containing the same atomic cobalt content were investigated. Thermoanalytical and previous studies, reveal that the\\u000a decomposition begins with cobalt clustering which initiates the precipitation of the Co2Si stoichiometric particles, which in turn dissolves after further heating. Volume fractions are unequivocally determined\\u000a by the amount

  14. Scintillator materials for calorimetry

    SciTech Connect

    Weber, M.J. [Lawrence Berkeley Lab., CA (United States). Life Sciences Div.

    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.

  15. Cryomilled Aluminum with Diamantane: Thermal Characterization by DSC and Effects of Magnesium

    NASA Astrophysics Data System (ADS)

    Arnold, Michael Colin

    Many structural applications require a material that is both lightweight and corrosion resistant, for which aluminum and its alloys may be considered for use if not for their relatively low strength. By improving strength of aluminum through the Hall-Petch mechanism, it could become a more suitable choice for many structural applications. Cryomilling is used as a production technique to strengthen aluminum by reduction of grain size to the 20-50 nm range. Although the powders produced by cryomilling are well within the nanocrystalline regime, the powders experience significant grain growth during consolidation to a solid body. Cryomilled powders have been shown to remain nanocrystalline by introducing a nano-diamond, diamantane to the grain boundaries. To better characterize the thermal stability of the cryomilled powder with diamantane, Differential Scanning Calorimetry (DSC) was used to measure the isothermal heat flow in the 0.6Tm to 0.9Tm range. A model was developed to correlate the isothermal DSC signal to a grain growth curve and grain growth parameters were elucidated by assuming variable boundary mobility with a sigmoidal form. The model revealed a tendency for boundary mobility to transition from an athermal grain growth mechanism to standard thermally activated grain growth. Grain growth parameters were compared to shed light on possible mechanisms of aluminum-diamantane involvement during grain growth. Powders and consolidated samples with very low concentrations of diamantane and with magnesium were observed by TEM, SEM and XRD, and compared both separately and together to characterize the how thermal stability is affected by diamantane concentration and the presence of magnesium.

  16. An improved DSC glass sample container technique

    Microsoft Academic Search

    Ivan J. Goldfarb; Hongtu Feng; Jimmie C. Oxley

    1996-01-01

    A simple method has been developed for the use of glass capillaries in DSC. The metal block holder used by previous workers was found to be unnecessary. It was found that different positions of the glass capillary in the cell or long term use of the same baseline do not affect the DSC curves for the same samples. The experimental

  17. Characterization of petroleum products by DSC analysis

    Microsoft Academic Search

    C. Giavarini; F. Pochetti

    1973-01-01

    Some petroleum products, as paraffin waxes, microcrystalline waxes, lube oils, fuel oils, bitumens, were studied using DSC. DSC makes it possible to determine the wax content of various petroleum fractions, to study the effects of additives, to determine the glass transitions of bitumens; it is a useful technique both for research and for product analysis.

  18. Characterization of forages by differential scanning calorimetry and prediction of their chemical composition and nutritive value

    Microsoft Academic Search

    J Walshaw; G. W Mathison; T. F Fenton; G Sedgwick; H Hsu; G Recinos-Diaz; A Suleiman

    1998-01-01

    Differential scanning calorimetry (DSC) measurements of grass and legume hay samples were made to determine the potential of using this technique to estimate forage chemical composition and cattle intake and digestibility parameters. Ninety-three hay samples were examined, with 56 samples being used for development of calibration equations relating 17 forage chemical parameters and animal measurements to heat fluxes in response

  19. NMR relaxometry and differential scanning calorimetry during meat cooking.

    PubMed

    Bertram, Hanne Christine; Wu, Zhiyun; van den Berg, Frans; Andersen, Henrik J

    2006-12-01

    By combining simultaneous nuclear magnetic resonance (NMR) T(2) relaxometry and differential scanning calorimetry (DSC) on pork samples heated to nine temperature levels between 25 and 75°C, the present study investigates the relationship between thermal denaturation of meat proteins and heat-induced changes in water characteristics. Principal component analysis (PCA) on the distributed (1)H NMR T(2) relaxation data revealed that the major changes in water characteristics during heating occur between 40 and 50°C. This is probably initiated by denaturation of myosin heads, which however, could not be detected in the DSC thermograms obtained directly on the meat. In contrast, the DSC thermograms revealed endothermic transitions at 54, 65 and 77°C, probably reflecting the denaturation of myosin (rods and light chain), sarcoplasmic proteins together with collagen and actin, respectively. Simultaneous modelling of DSC and NMR data by partial least squares regression (PLSR) revealed a correlation between denaturation of myosin rods and light chains at ?53-58°C and heat-induced changes in myofibrillar water (T(2) relaxation time ?10-60ms) as well as between actin denaturation at ?80-82°C and expulsion of water from the meat. Accordingly, the present study demonstrates a direct relationship between thermal denaturation of specific proteins/protein structures and heat-induced changes in water mobility during heating of pork. PMID:22063224

  20. 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.

  1. Characterization of the Polycaprolactone Melt Crystallization: Complementary Optical Microscopy, DSC, and AFM Studies

    PubMed Central

    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. PMID:24523644

  2. The effects of urea and n-propanol on collagen denaturation: using DSC, circular dicroism and viscosity

    Microsoft Academic Search

    R. Usha; T. Ramasami

    2004-01-01

    The effect of urea and n-propanol on circular dichroism (CD) and viscosity of purified type1 collagen solution at various temperatures and differential scanning calorimetry (DSC) of rat-tail tendon (RTT) collagen fibre have been studied. CD reveals a spectrum with a positive peak at around 220nm and a negative peak at 200nm characteristics of collagen triple helix. The molar ellipticity decreases

  3. Energetic and Kinetic Evaluations Conducted in a Quasi-Binary Cu?1 at% Co2Si Alloy Through DSC

    Microsoft Academic Search

    A. Varschavsky; E. Donoso

    2002-01-01

    By means of differential scanning calorimetry (DSC) the precipitation process from a supersaturated solid solution of Cu?0.65\\u000a at% Co?0.33 at% Si (Cu?1 at% Co2Si) was investigated. On the basis of enthalpimetric calculations it was found that the decomposition\\u000a begins with cobalt precipitation. Clustering of atoms of cobalt initiates the precipitation of silicon, and particles of the\\u000a stoichiometric Co2Si composition are

  4. Determination of oxidation parameters by DSC for polypropylene stabilized with hydroxytyrosol (3,4-dihydroxy-phenylethanol)

    Microsoft Academic Search

    M. Peltzer; A. Jiménez

    2009-01-01

    Oxidation thermal parameters on samples of polypropylene (PP) stabilized with hydroxytyrosol were determined. For comparison\\u000a purposes, ?-tocopherol and a synthetic phenolic commercial antioxidant (Irganox 1076), were also analyzed. Oxidation induction\\u000a time (OIt) and oxidation induction temperature (OIT) were determined by differential scanning calorimetry (DSC). The addition\\u000a of hydroxytyrosol 0.1 mass% to PP was enough to obtain efficient stabilization during processing.

  5. DSC SUBMISSION TO THE UNIVERSITY OF SOUTHAMPTON

    E-print Network

    Chen, Sheng

    DSC SUBMISSION TO THE UNIVERSITY OF SOUTHAMPTON Intelligent Nonlinear Learning Machines by Dr. S. Chen School of Electronics and Computer Science University of Southampton Southampton SO17 1BJ, UK sqc to appreciate any intellectual gift one was born with. Sheng Chen School of ECS University of Southampton 1 #12

  6. A preliminary investigation of the application of differential scanning calorimetry to the study of collagen degradation in archaeological bone

    Microsoft Academic Search

    Christina M Nielsen-Marsh; Robert E. M Hedges; Tim Mann; Matthew J Collins

    2000-01-01

    The study investigated the potential application of differential scanning calorimetry (DSC) to archaeological bone collagen deterioration. The thermal transition of collagen was compared with the preservation state of the bones. Methods of sample preparation were shown to have a significant effect upon the ability to extract reproducible, reliable thermal data from the collagen. Three main protocols were examined, but the

  7. Comparison of normal and in vitro aging by non-enzymatic glycation as verified by differential scanning calorimetry.

    PubMed

    Reihsner, R; Pfeiler, W; Menzel, E J

    1998-01-01

    The biomechanical parameters of rat tail tendons (RTTs) from 35-, 64-, 180- and 900-day-old animals, corresponding to the early maturation phase, the mature and the senescent state were determined. The increase of maximum stiffness, ultimate stress and the elastic fraction of stress was most pronounced in the maturation phase. Differential scanning calorimetry (DSC) experiments were performed showing an almost linear increase of the collagen denaturation temperature in the age range 35-139 days. After 14 days incubation in glucose, we observed a marked increase of the biomechanical parameters in the young, an increase of maximum stiffness in mature, and only slight alterations of the biomechanical behavior in senescent RTTs. Both glucose incorporation and formation of advanced glycation end products were most prominent in 35-day-old RTTs. These biochemical findings were in excellent agreement with the enhancement of the collagen denaturation temperature after the incubation phase. Results suggest that the validity of the term 'accelerated aging' depends on the experimental approach, i.e. biomechanical tests, thermal isometric contraction or DSC. PMID:9523219

  8. Intracellular ice formation in yeast cells vs. cooling rate: Predictions from modeling vs. experimental observations by differential scanning calorimetry?

    PubMed Central

    Seki, Shinsuke; Kleinhans, F.W.; Mazur, Peter

    2013-01-01

    To survive freezing, cells must not undergo internal ice formation during cooling. One vital factor is the cooling rate. The faster cells are cooled, the more their contents supercool, and at some subzero temperature that supercooled cytoplasm will freeze. The question is at what temperature? The relation between cooling rate and cell supercooling can be computed. Two important parameters are the water permeability (Lp) and its temperature dependence. To avoid intracellular ice formation (IIF), the supercooling must be eliminated by dehydration before the cell cools to its ice nucleation temperature. With an observed nucleation temperature of ?25°C, the modeling predicts that IIF should not occur in yeast cooled at <20°C/min and it should occur with near certainty in cells cooled at ? 30°C/min. Experiments with differential scanning calorimetry (DSC) confirmed these predictions closely. The premise with the DSC is that if there is no IIF, one should see only a single exotherm representing the freezing of the external water. If IIF occurs, one should see a second, lower temperature exotherm. A further test of whether this second exotherm is IIF is whether it disappears on repeated freezing. IIF disrupts the plasma membrane; consequently, in a subsequent freeze cycle, the cell can no longer supercool and will not exhibit a second exotherm. This proved to be the case at cooling rates > 20°C/min. PMID:19118541

  9. Curing kinetics of arylamine-based polyfunctional benzoxazine resins by dynamic differential scanning calorimetry

    Microsoft Academic Search

    Chanchira Jubsilp; Siriporn Damrongsakkul; Tsutomu Takeichi; Sarawut Rimdusit

    2006-01-01

    In this study, the curing kinetics of polyfunctional benzoxazine resins based on arylamine, i.e. aniline and 3,5-xylidine, designated as BA-a and BA-35x, respectively, were investigated. Non-isothermal differential scanning calorimetry (DSC) at different heating rates is used to determine the kinetic parameters and the kinetic models of the curing processes of the arylamine-based polyfunctional benzoxazine resins were proposed. Kissinger, Ozawa, Friedman,

  10. Thermal analysis of flaxseed ( Linum usitatissimum) proteins by differential scanning calorimetry

    Microsoft Academic Search

    E. C. Y Li-Chan; C.-Y Ma

    2002-01-01

    The thermal properties of flaxseed (whole or dehulled), dehulled and delipidated meal, as well as proteins extracted and isolated from the meal, were investigated by differential scanning calorimetry (DSC). A high denaturation temperature (Td) of 114.7 °C was observed for the major fraction of flaxseed protein isolated by anion-exchange chromatography, representing the 11–12 S storage globulin. Marked decreases in Td and

  11. Effect of thermal denaturation on water-collagen interactions: NMR relaxation and differential scanning calorimetry analysis.

    PubMed

    Rochdi, A; Foucat, L; Renou, J P

    1999-12-01

    The dependence of the proton spin-lattice relaxation rate, and of the enthalpy and temperature of denaturation on water content, were studied by nmr and differential scanning calorimetry (DSC) in native and denatured collagen. Collagen was first heated at four different temperatures ranging from 40 to 70 degrees C. The percentage of denatured collagen induced by these preheating treatments was determined from DSC measurements. The DSC results are discussed in terms of heat-induced structural changes. A two-exponential behavior for the spin-lattice relaxation was observed with the appearance of denatured collagen. This was attributed to the presence of a noncollagen protein fraction. The variations in the different longitudinal relaxation rates as a function of the moisture content and of the denatured collagen percentage are described within the multiphase water proton exchange model. This study highlights the complementarity of the information obtained from the two analytical tools used. PMID:10547524

  12. New methodology developed for the differential scanning calorimetry analysis of polymeric matrixes incorporating phase change materials

    NASA Astrophysics Data System (ADS)

    Barreneche, Camila; Solé, Aran; Miró, Laia; Martorell, Ingrid; Inés Fernández, A.; Cabeza, Luisa F.

    2012-08-01

    Nowadays, thermal comfort needs in buildings have led to an increase in energy consumption of the residential and service sectors. For this reason, thermal energy storage is shown as an alternative to achieve reduction of this high consumption. Phase change materials (PCM) have been studied to store energy due to their high storage capacity. A polymeric material capable of macroencapsulating PCM was developed by the authors of this paper. However, difficulties were found while measuring the thermal properties of these materials by differential scanning calorimetry (DSC). The polymeric matrix interferes in the detection of PCM properties by DSC. To remove this interfering effect, a new methodology which replaces the conventional empty crucible used as a reference in the DSC analysis by crucibles composed of the polymeric matrix was developed. Thus, a clear signal from the PCM is obtained by subtracting the new full crucible signal from the sample signal.

  13. Thermal behavior and phase identification of Valsartan by standard and temperature-modulated differential scanning calorimetry.

    PubMed

    Skotnicki, Marcin; Gawe?, Agnieszka; Cebe, Peggy; Pyda, Marek

    2013-10-01

    Thermal behavior of angiotensin II type 1 (AT1) receptor antagonist, Valsartan (VAL), was examined employing thermogravimetric analysis (TGA), standard differential scanning calorimetry (DSC) and temperature-modulated differential scanning calorimetry (TMDSC). The stability of VAL was measured by TGA from 25 to 600°C. Decomposition of Valsartan starts around 160°C. The DSC curve shows two endotherms, occurring around 80°C and 100°C, related to evaporation of water and enthalpy relaxation, respectively. Valsartan was identified by DSC as an amorphous material and it was confirmed by X-ray powder diffraction. The glass transition of fresh Valsartan appears around 76°C (fictive temperature). TMDSC allows separation of the total heat flow rate into reversing and nonreversing parts. The nonreversing curve corresponds to the enthalpy relaxation and the reversing curve shows changes of heat capacity around 94°C. In the second run, TMDSC curve shows the glass transition process occurring at around 74°C. Results from standard DSC and TMDSC of Valsartan were compared over the whole range of temperature. PMID:22803969

  14. Calorimetry Triggering in ATLAS

    SciTech Connect

    Igonkina, O.; /NIKHEF, Amsterdam; Achenbach, R.; /Kirchhoff Inst. Phys.; Adragna, P.; /Queen Mary, U. of London; Aharrouche, M.; /Mainz U., Inst. Phys.; Alexandre, G.; /Geneva U.; Andrei, V.; /Kirchhoff Inst. Phys.; Anduaga, X.; /La Plata U.; Aracena, I.; /SLAC; Backlund, S.; /CERN; Baines, J.; /Rutherford; Barnett, B.M.; /Rutherford; Bauss, B.; /Mainz U., Inst. Phys.; Bee, C.; /Marseille, CPPM; Behera, P.; /Iowa State U.; Bell, P.; /Manchester U.; Bendel, M.; /Mainz U., Inst. Phys.; Benslama, K.; /Regina U.; Berry, T.; /Royal Holloway, U. of London; Bogaerts, A.; /CERN; Bohm, C.; /Stockholm U.; 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.

  15. Differential scanning calorimetry of lupin and soy proteins.

    PubMed

    Sousa, I M; Mitchell, J R; Ledward, D A; Hill, S E; da Costa, M L

    1995-12-01

    Differential scanning calorimetry (DSC) was used to study the 7S and 11S globulin fractions extracted from lupin seed (Lupinus luteus) flour. In agreement with previous work on other lupin species, the isolate showed three denaturation peaks compared to the two observed with soy. By comparison with the isolated globulin fractions, the denaturation peaks at the two higher temperatures in the lupin isolate were assigned to the 11S and 7S globulins. The denaturation temperature of the lupin 7S globulin was about 10 K higher than that for the corresponding soy globulin, whereas the values for the 11S globulin were similar. All globulins displayed increasing thermal stability with decreasing moisture contents. Possible reasons for the differences in behaviour of soy and lupin protein isolates are discussed. PMID:8585334

  16. REDES DE COMPUTADORES UFPB / CCT / DSC / PSN, 2001 * Parte 4: Estudo de Caso -DSC * Pg. 1

    E-print Network

    Cirne, Walfredo

    de iniciação científica LSD - Laboratório de Sistemas Distribuídos, de uso específico dos Firewall DSC Server 1 UNIX Server 2 UNIX Server 1 Windows LabCom LSD LEPRECOM LSI LabPetri LAD LIA Miniblio ao setor (no caso do LSD, LEPRECOM, LSI, LIA e LabPetri). ! Os setores (nuvens) em amarelo, usam

  17. Step-scan Alternating Differential Scanning Calorimetry Studies on the Crystallisation Behaviour of Low Molecular Weight Polyethylene

    NASA Astrophysics Data System (ADS)

    Pielichowska, Kinga; Pielichowski, Krzysztof

    Differential scanning calorimetry (DSC) and step-scan alternating (SSA) DSC were applied to investigate the crystallisation behaviour of polyethylene (PE) with molecular weight of 4000, 15000 and 35000. It has been found that PE 15000 is characterised by the highest degree of crystallinity and by the highest crystallisation temperature, as compared with other PE samples studied in the course of this work. The non-reversing component of the crystallisation process depends strongly on the PE molecular weight; parallelly, the reversing component shows minor fluctuations only, confirming thus the irreversibility of the PE crystallisation process.

  18. 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.

  19. Cdf II Integrated Calorimetry Environment

    NASA Astrophysics Data System (ADS)

    Dell'Agnello, S.

    2002-01-01

    The Run IIa integrated calorimetry environment of CDF II comprises: sampling scintillator calorimeters, e.m. pre-shower and shower-maximum detectors (gas based in the central, scintillator based in the forward), crack-filler detectors, radioactive source calibration systems, light pulse calibration systems, dedicated triggers for critical low energy calibrations, new FEE, a Windows NT slow control system, the master online-offline Oracle Database and an online data validation framework, distilled over the previous years of CDF data taking (now based on the CERN Root). The pre-existing central calorimeters are the bridge between the energy and time measurement of the past and current physics runs. New forward calorimeters (the "plugs"), built with the modern scintillating tile-fiber technique, replaced the old gas calorimeters. Together they form an integrated, general-purpose calorimetry system which has been successfully commissioned with the 2000-2001 collider data. The time measurement, before present only in the central hadron, has now been extended the plug hadron calorimeter. To complete the integration in Run IIb (>2004), the central gas pre-shower will be replaced with a tile-fiber detector and the time information will be added also to the e.m. calorimeters. Select jet energy topics are described which show how the CDF II calorimetry has the capability to improve the measurement of the W and the top-quark masses, and to enhance the search for dijet mass peaks in conjunction with b-tagging.

  20. Differential Scanning Calorimetry Study of Normal Portland Cement Paste with 30% Fly Ash Replacement and of the Separate Fly Ash and Ground Granulated Blast-Furnace Slag Powders

    Microsoft Academic Search

    W. Sh; G. B. Pereira

    Synopsis: This paper reports a differential scanning calorimetry (DSC) study of the hydration and pozzolanic processes in normal portland cement paste containing fly ash. First, the thermal stability of fly ash powder was investigated, the result showing mainly the crystallisation of the amorphous phase(s) in the material. The heat evolution during constant rate heating of a normal portland cement paste

  1. Characterization of Soluble Amaranth and Soybean Proteins Based on Fluorescence, Hydrophobicity, Electrophoresis, Amino Acid Analysis, Circular Dichroism, and Differential Scanning Calorimetry Measurements

    Microsoft Academic Search

    Shela Gorinstein; Efren Delgado-Licon; Elke Pawelzik; Herry Heriyati Permady; Moshe Weisz; Simon Trakhtenberg

    2001-01-01

    Intrinsic fluorescence (IF), surface hydrophobicity (So), electrophoresis, amino acid analysis, circular dichroism (CD), and differential scanning calorimetry (DSC) were used to study folded and unfolded soluble proteins from Amaranthus hypochondriacus (A. h.) and soybean (S). Globulin (Glo) and albumin subfractions (Alb-1 and Alb-2) were extracted from A. h. and S and denatured with urea. Electrophoretic and functional properties indicated a

  2. A differential scanning calorimetry study on poly(ethylene terephthalate) isothermally crystallized at stepwise temperatures: multiple melting behavior re-investigated

    Microsoft Academic Search

    E. M. Woo; T. Y. Ko

    1996-01-01

    The multiple melting behavior of poly(ethylene terephthalate) (PET) was investigated with differential scanning calorimetry (DSC) by examining PET samples having been subjected to special schemes of crystallization and annealing treatment at multiple descending temperatures. Upon such step-wise annealing in decreasing temperatures, the existence of doublet melting peaks in addition to a series of multiple minor peaks in the PET has

  3. Thermally induced structural changes of acetaminophen in phase transition between the solid and liquid states monitored by combination analysis of FT-IR\\/DSC microscopic system

    Microsoft Academic Search

    S.-Y Lin; S.-L Wang; Y.-D Cheng

    2000-01-01

    The molecular structure of acetaminophen in solid\\/liquid phase transition states was simply investigated by Fourier transform infrared (FT-IR) microspectroscopy equipped with differential scanning calorimetry (DSC). The result indicated that the intermolecular hydrogen bonds in the solid-state acetaminophen molecules were dramatically broken from 165°C, and loosened its molecular structure and packing to induce the phase transition between solid and liquid states.

  4. Hyperspectral image lossless compression using DSC and 2-D CALIC

    Microsoft Academic Search

    Xueping Yan; Jiaji Wu

    2010-01-01

    In recent few years, DSC (Distributed Source Coding) technology is catched much attentions in remote sensing image compression field,due to its excellent performance and low encoding complexity. In this paper, we propose a DSC-based practical solution for hyperspectral image lossless compression system, which applies the DSC technique using the power channel codes of Low-Density-Parity-Check Accumulated(LDPCA) codes and incorporates an efficient

  5. DSC: Scheduling Parallel Tasks on an Unbounded Number of Processors

    Microsoft Academic Search

    Tao Yang; Apostolos Gerasoulis

    1994-01-01

    We present a low-complexity heuristic, named the dominant sequence clusteringalgorithm (DSC), for scheduling parallel tasks on an unbounded number of completelyconnected processors. The performance of DSC is on average, comparable to, or evenbetter than, other higher-complexity algorithms. We assume no task duplication andnonzero communication overhead between processors. Finding the optimum solution forarbitrary directed acyclic task graphs (DAG's) is NP-complete. DSC

  6. Molecular interactions between DPPC and morphine derivatives: a DSC and EPR study.

    PubMed

    Budai, M; Szabó, Zs; Szogyi, M; Gróf, Pál

    2003-01-01

    The interaction between different morphine derivatives (morphine, codeine, N-methyl-morphine, N-methyl-codeine) and alpha-L-dipalmitoyl phosphatidylcholine (DPPC) liposomes was studied with differential scanning calorimetry (DSC) and electron paramagnetic resonance (EPR) spectroscopy. Small unilamellar DPPC-liposomes with the given morphine-derivative were prepared by sonication. The size distribution of liposomes was checked by dynamic light scattering (DLS). The amount of entrapped morphine was determined spectrophotometrically. Our results indicate that the morphine and its derivatives principally interact with the lipid head groups, and this interaction leads to a decrease in the mobility of the polar head groups, especially in case of codeine and N-methyl-codeine. PMID:12480289

  7. Effect of mesogenic group on micro-phase phase separated structures of block copolymers studied by DSC-SAXS method

    Microsoft Academic Search

    Takeshi YAMADA; Takayuki SHIRAISHI; Hirohisa YOSHIDA

    2009-01-01

    Experiments The simultaneous DSC-XRD measurements (4) were performed by SAXS optics at BL-10C, PF, KEK. The wavelength of X-ray and the measurement range of scattering vector were 0.1488 nm and 0.06 nm -1 < q (=4?sin?\\/?) < 3 nm -1 , respectively. DSC scanning rate and XRD time resolution were 2 K min -1 and 30 sec, respectively. Manuscript preparation

  8. Quantification of the leaching of triethyl citrate\\/polysorbate 80 mixtures from Eudragit ® RS films by differential scanning calorimetry

    Microsoft Academic Search

    Ronny Gruetzmann; Karl G. Wagner

    2005-01-01

    The influence of triethyl citrate and polysorbate 80 (Tween® 80) on the glass transition temperature (TG) of Eudragit® RS membranes was investigated using differential scanning calorimetry (DSC). The TG-decreasing effect of TEC and Tween® 80 displayed an almost identical performance in extent at a linear relationship between weight proportion and TG resulting in a specific TG-decrease (TG,spec.) of ?1.98(K\\/%TEC) and

  9. Determination of curing kinetic parameters of lignin–phenol–formaldehyde resol resins by several dynamic differential scanning calorimetry methods

    Microsoft Academic Search

    M. V. Alonso; M. Oliet; J. M. Pérez; F. Rodr??guez; J. Echeverr??a

    2004-01-01

    The curing kinetics of lignin–phenol–formaldehyde (LPF) and phenol–formaldehyde (PF) resol resins was studied by non-isothermal differential scanning calorimetry (DSC) at different heating rates. The data were fitted by means of the Borchardt–Daniels, Ozawa and Kissinger methods, which allow determining the kinetic parameters of both resins. The kinetic study has been realized to evaluate the effect of methylolated ammonium lignin sulfonate

  10. 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. PMID:24856323

  11. Effect of collagen crosslinking on collagen-water interactions (a DSC investigation).

    PubMed

    Kopp, J; Bonnet, M; Renou, J P

    1989-01-01

    The effect of collagen cross-linking state on the collagen-water interaction was studied, using Differential Scanning Calorimetry (DSC) which allows the determination of unfreezable water, the variation of enthalpy (delta H) and temperatures of denaturation of collagen to gelatin transition. DSC was performed on intramuscular connective tissue purified with trypsin (control C), depolymerized with penicillamin (P), and reduced with borohydride (B); samples were adjusted with different water contents. For the three tissues, unfreezable water (Wu) and denaturation enthalpy change (delta H) increased with increasing moisture level (Wt); whereas, maximum denaturation temperature (phi M) decreased. The ability of this calorimetric method of investigation to characterize the collagen crosslink state is discussed: maximum limit values of delta H and of Wu decreased significantly with increasing collagen cross-linking degree. Minimum Wt necessary to reach the maximum delta H decreased with crosslinking degree. Likewise significantly different limit values of unfreezable water Wu were reached for smaller Wt the greater the crosslinking of collagen. These results show that the less connective tissues were cross-linked, the more they could bind water. They also demonstrated that the water of collagen hydration can be classified into four states, whose limits vary according to the degree of crosslinking. PMID:2635757

  12. 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.

  13. 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.

  14. Influence of collagen denaturation on the chemorheological properties of skin, assessed by differential scanning calorimetry and hydrothermal isometric tension measurement.

    PubMed

    le Lous, M; Flandin, F; Herbage, D; Allain, J C

    1982-08-01

    The curves obtained for skin samples of different ages and species by hydrothermal isometric tension ("HIT") measurement are compared to those obtained by differential scanning calorimetry (DSC) under the same thermal conditions (for a rise in temperature at a rate of 1.0 degrees C/min). Collagen denaturation, observed by DSC, directly affects the kinetics of the tension variations in the first part of the "HIT" curves, including the early peak due to the presence and destruction of the heat-labile cross-links in the collagen network. The presence of cross-links is in term shown to delay collagen denaturation to an extent which depends in part on their heat-stability. The final part of the "HIT" curves reflecting the effects of heat in the stable polymeric collagen network is no longer affected by collagen denaturation. Thus, both "HIT" and DSC are useful methods to evaluate collagen reticulation in connective tissues. PMID:7115770

  15. Analysis of Fluxless, Reactive Brazing of Al Alloys Using Differential Scanning Calorimetry

    NASA Astrophysics Data System (ADS)

    Corbin, Stephen Francis; Winkler, Sooky; Turriff, Dennis R.; Kozdras, Mark

    2014-08-01

    During this investigation, a technique was developed, using differential scanning calorimetry (DSC), to quantitatively analyze the influence of a Ni-based electrolytic braze promotor surface deposit on the furnace brazing of aluminum alloys. The purpose of this braze promoter was to induce a large exothermic surface reaction capable of disrupting a tenacious oxide present on the aluminum braze sheet faying surface. A cyclic DSC methodology was developed which was capable of a quantitative determination of the exothermic reaction (? H exo) induced by the Ni plating. Samples with a small quantity of Ni plating exhibited significant "pre-reaction" between Ni and Al in the solid state which resulted in very low ? H exo values. Samples with higher quantities of Ni plating exhibited large ? H exo values up to 85 kJ/mole.

  16. Thermal dissection of lentil seedling amine oxidase domains by differential scanning calorimetry.

    PubMed

    Moosavi-Movahedi, Ali Akbar; Amani, Mojtaba; Moosavi-Nejad, Seyedeh Zahra; Hashemnia, Sedigheh; Ahmad, Faizan; Floris, Giovanni; Mura, Anna; Rezaei-Tavirani, Mostafa; Hakimelahi, Gholam Hossein; Saboury, Ali Akbar; Yousefi, Reza

    2007-07-01

    The relationships between the structural and energetic domains of lentil seedling amine oxidase (LSAO) were investigated using modifiers that target the active site and the carbohydrate moiety of the enzyme. An irreversible inhibitor, aminoguanidine, specifically modified the active site of the lentil enzyme, whereas sodium metaperiodate cleaves carbohydrate moieties covalently bound to the native enzyme. Differential scanning calorimetry (DSC) measurements were made on the modified LSAOs. Deconvolution of the reversible thermal DSC profiles of the modified enzyme gave three subpeaks (energetic domains), each of which was assigned to one of the three structural domains of the native protein. Our results led us to conclude that deglycosylation of LSAO has no effect on thermal stability, whereas binding of the inhibitor imparts more stability to the enzyme. PMID:17617729

  17. Comparison of TSSD results obtained by differential scanning calorimetry and neutron diffraction

    NASA Astrophysics Data System (ADS)

    Khatamian, D.; Root, J. H.

    2008-01-01

    Due to their low absorption cross-section for neutrons, Zr alloys are used for reactor core components. The terminal solid solubility (TSS) for hydrogen in these alloys is very low - in Zr-2.5 wt% Nb, used to fabricate pressure tubes for CANDU (CANDU-CANada Deuterium Uranium is a registered trademark of Atomic Energy of Canada Ltd.) power reactors, the TSS is ˜0.7 at.% H at 300 °C. The mechanical properties of the components may deteriorate when their hydrogen concentration exceeds TSS. Therefore, accurate values of the TSS are needed to assess the operating and end-of-life behaviours of these components. Differential scanning calorimetry (DSC) is used to measure the TSS of hydrogen in Zr alloys. Three distinct features are marked on a typical DSC heat flow curve when the material is being heated and the hydrides are dissolving; 'peak temperature', 'maximum slope temperature' and 'completion temperature'. Usually, the maximum slope temperature, being about the average of the three temperatures, is interpreted as the TSS temperature for hydride dissolution ( TTSSD). A set of coordinated DSC and neutron diffraction measurements have been carried out to identify the features of the heat flow signal that closely correspond to the TTSSD. Neutron diffraction was chosen because hydrides generate distinctive diffraction peaks whose intensities approach zero at the transition temperature - an unambiguous indication of dissolution. Neutron diffraction shows that the temperature of hydride dissolution correlates closely with the DSC peak temperature.

  18. Applying differential scanning calorimetry to characterize chemical-protective-clothing materials. Final report

    SciTech Connect

    Weidenbaum, S.S.

    1991-01-01

    The use of differential scanning calorimetry as a means of evaluating changes in polymers used to manufacture protective clothing was investigated. Separate enclosed Appendices give details of studies dealing with Vitron (R)/chlorobutyl laminate. These are preceded by a Summary which gives information dealing with Teflon-coated Nomex (Challenge (TM) 5100). The manner in which DSC graphs were affected by exposing the polymers to a variety of chemicals is the main subject of the report. However, some information dealing with thermogravimetric analysis (TGA), viscoelastic measurements and solubility parameters is also in the various appendices.

  19. NMR and DSC studies during thermal denaturation of collagen

    Microsoft Academic Search

    Abderrahim Rochdi; Jean-Pierre Renou

    2000-01-01

    Epimysial and intramuscular connective tissues from calf and cow muscle were studied by NMR and DSC. Water proton NMR transverse relaxation times (T2) were measured at 10°C for both native and thermally-denatured at 90°C for 30–360 min. DSC measurements were used to determine the temperature and the variation enthalpy of sol?gel transition. According to the heating time, significant differences were

  20. Tritium inventory measurements using calorimetry

    SciTech Connect

    Kapulla, H.; Kraemer, R.; Heine, R. (Kernforschungszentrum Karlsruhe GmbH (Germany))

    1992-03-01

    In the past calorimetry has been developed as a powerful tool in radiometrology. Calorimetric methods have been applied for the determination of activities, half lives and mean energies released during the disintegration of radioactive isotopes. The fundamental factors and relations which determine the power output of radioactive samples are presented and some basic calorimeter principles are discussed in this paper. At the Kernforschungszentrum Karlsruhe (KfK) a family of 3 calorimeters has been developed to measure the energy release from radiative waste products arising from reprocessing operations. With these calorimeters, radiative samples with sizes from a few cm{sup 3} to 2 {center dot}10{sup 5} cm{sup 3} and heat ratings ranging from a few nW to kW can be measured. After modifications of tits inner part the most sensitive calorimeter among the three calorimeters mentioned above would be best suited for measuring the tritium inventory in T-getters of the Amersham-type.

  1. Comparison of reversible melting behaviour of poly(3-hydroxybutyrate) using quasi-isothermal and other modulated temperature differential scanning calorimetry techniques

    Microsoft Academic Search

    R. A. Shanks; L. M. W. K. Gunaratne

    2011-01-01

    Melting behaviour of poly(3-hydroxybutyrate) (PHB) has been investigated by conventional DSC and each of several methods of\\u000a modulated temperature differential scanning calorimetry (mT-DSC) such as heat-cool, iso-scan, step-scan and quasi-isothermal\\u000a (QI). Thermal properties were investigated after fast and slow cooling crystallisation treatments. Multiple melting peak behaviour\\u000a was observed for all methods except conventional melting with an average heating rate. Comparison

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

    PubMed

    Mazurek-Wado?kowska, Edyta; Winnicka, Katarzyna; Czajkowska-Ko?nik, 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. PMID:24147356

  3. Assignment of the human genes for Desmocollin 3 (DSC3) and Desmocollin 4 (DSC4) to chromosome 18q12

    SciTech Connect

    Amagai, Masayuki; Nishikawa, Takeji; Wang, Yimin [Keio Univ. School of Medicine, Shinjuku-ku, Tokyo (Japan)] [and others] [Keio Univ. School of Medicine, Shinjuku-ku, Tokyo (Japan); and others

    1995-01-01

    Desmosomes are adhesive intercellular junctions that contain two transmembrane components, desmoglein and desmocollin. cDNA cloning has revealed that both components are members of the cadherin supergene family and consist of multiple isotypes. Desmogleins (Dsg) have three isotypes, Dsg1, Dsg2, and Dsg3. Dsg1 and Dsg3 are also the target antigens of autoimmune blistering diseases, pemphigus foliaceus and pemphigus vulgaris, respectively. Previously, we have demonstrated that the human genes for Dsg1 and Dsg3 are located on chromosome 18q12 by fluorescence in situ hybridization (FISH). Furthermore, both genes were localized on a 320-kb genomic fragment separated by pulsed-field gel electrophoresis. For desmocollins (Dsc for protein, DSC for gene), human cDNAs for Dsc1 and Dsc3 have been isolated from three currently known isotypes. In this study, we report that human genes for Dsc3 and a novel desmocollin, Dsc4, are located on chromosome 18q12 as determined by FISH, suggesting a cluster for desmosomal cadherins on chromosome 18. 14 refs., 1 fig.

  4. Determination of the nateglinide polymorphic purity through DSC.

    PubMed

    Bruni, G; Berbenni, V; Milanese, C; Girella, A; Cardini, A; Lanfranconi, S; Marini, A

    2011-04-01

    It is well known that the control of the crystallization of drugs to ensure that only the approved and desired polymorph is present in the formulation is a crucial point of a preformulation study. In this regard, the aim of the present work is to devise a method for the quantification of the polymorphic purity of nateglinide in mixtures formed by polymorphs H and B. In order to achieve this goal, binary systems of known composition have been prepared and the melting peaks of both polymorphs have been recorded by differential scanning calorimetry. Experiments have determined that the method of preparation of the mixtures has to be carefully evaluated. Indeed it has been shown that grinding the samples induces transition from B to H form. Furthermore, it could be observed that the enrichment of the binary mixture with H form is caused by heating. Therefore, after having prepared the mixture without grinding stage, we propose a method to evaluate the content of H polymorph in mixture with the B one from the melting peak of B. PMID:21216126

  5. 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.

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

    PubMed

    Pielesz, Anna; Machnicka, Alicja; Gaw?owski, Andrzej; Fabia, Janusz; Sarna, Ewa; Binia?, W?odzimierz

    2015-06-15

    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 ?-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. PMID:26029873

  7. Thermal properties of cowpea flour: a study by differential scanning calorimetry.

    PubMed

    Henshaw, Folake O; McWatters, Kay H; Akingbala, John O; Chinnan, Manjeet S

    2003-06-01

    The thermal properties of 12 varieties of cowpea flour were studied by differential scanning calorimetry (DSC). Flour samples were prepared to a paste of 60% moisture content and sealed in standard DSC pans. Samples were scanned at a heating rate of 5 degrees C/min over a scan range of 40- 130 degrees C. Samples exhibited single major endotherms, which occurred over varied temperatures. The transition enthalpy (deltaH) ranged between 1.4 J/g and 4.7 J/g. Transition onset (T(o)) and transition peak (T(p)) temperatures ranged between 75-78 degrees C and 78-82 degrees C,respectively. All the DSC parameters measured varied significantly among the varieties. The transition enthalpy (deltaH) was the most discriminating parameter and accounted for 80% of the total variance. The major chemical components of cowpea flour, starch amylose and protein are significant predictors of deltaH. Protein denaturation appears to be a significant modification which occurs during processing of cowpea seeds to flour. The transition enthalpy deltaH could become an important functional index of cowpea flour when related to some quality parameters in products that contain the flour. PMID:12866616

  8. Interaction between the Cytochrome caa3 and F1F0-ATP Synthase of Alkaliphilic Bacillus pseudofirmus OF4 is Demonstrated by Saturation Transfer Electron Paramagnetic Resonance and Differential Scanning Calorimetry Assays

    PubMed Central

    Liu, Xiaoying; Gong, Xing; Hicks, David B.; Krulwich, Terry A.; Yu, Linda; Yu, Chang-An

    2008-01-01

    Interaction between the cytochrome caa3 respiratory chain complex and F1F0-ATP synthase from extremely alkaliphilic Bacillus pseudofirmus OF4 has been hypothesized to be required for robust ATP synthesis by this alkaliphile under conditions of very low protonmotive force. Here, such an interaction was probed by differential scanning calorimetry (DSC) and by saturation transfer electron paramagnetic resonance (STEPR). When the two purified complexes were embedded in phospholipids vesicles individually [(caa3) × PL, (F1F0) × PL)] or in combination [(caa3+F1F0) × PL] and subjected to DSC analysis, they underwent exothermic thermodenaturation with transition temperatures at 69, 57, and 46/75 °C, respectively. The enthalpy change, ?H, (?8.8 Kcal/mmol) of protein-phospholipid vesicles containing both cytochrome caa3 and F1F0 was smaller than that (?12.4 Kcal/mmol) of a mixture of protein-phospholipid vesicles formed from each individual electron transfer complex [(caa3 × PL) + (F1F0 × PL)]. The rotational correlation time of spin-labeled caa3 (65 µs) in STEPR studies increased significantly when the complex was mixed with F1F0 prior to being embedded in phospholipids vesicles (270 µs). When the complexes were reconstituted separately then mixed together, or either mitochondrial cytochrome bc1 or F1F0 was substituted for the alkaliphile F1F0, the correlation time was unchanged (65–70 µs). Varying the ratio of the two alkaliphile complexes in both the DSC and STEPR experiments indicated that the optimal stoichiometry is 1:1. These results demonstrate a specific interaction between the cytochrome caa3 and F1F0-ATP synthase from B. pseudofirmus OF4 in a reconstituted system. They support the suggestion that physical association between these complexes may contribute to sequestered proton transfers during alkaliphile oxidative phosphorylation at high pH. PMID:17198401

  9. Evolved gas analysis (EGA) in TG and DSC with single photon ionisation mass spectrometry (SPI-MS): molecular organic signatures from pyrolysis of soft and hard wood, coal, crude oil and ABS polymer

    Microsoft Academic Search

    T. Streibel; R. Geißler; M. Saraji-Bozorgzad; M. Sklorz; E. Kaisersberger; T. Denner; R. Zimmermann

    2009-01-01

    A combined thermogravimetry\\/differential scanning calorimetry device (TG\\/DSC) was coupled to single photon ionisation mass spectrometry (SPI-MS) for evolved gas analysis (EGA). Single photon ionisation (SPI) was performed with a new type of VUV light source, the so called electron beam pumped rare gas excimer lamp (EBEL). SPI does not fragment molecules upon the ionisation process. Thus the molecular mass signature

  10. Detection of Cervical Cancer Biomarker Patterns in Blood Plasma and Urine by Differential Scanning Calorimetry and Mass Spectrometry

    PubMed Central

    Garbett, Nichola C.; Merchant, Michael L.; Helm, C. William; Jenson, Alfred B.; Klein, Jon B.; Chaires, Jonathan B.

    2014-01-01

    Improved methods for the accurate identification of both the presence and severity of cervical intraepithelial neoplasia (CIN) and extent of spread of invasive carcinomas of the cervix (IC) are needed. Differential scanning calorimetry (DSC) has recently been shown to detect specific changes in the thermal behavior of blood plasma proteins in several diseases. This methodology is being explored to provide a complementary approach for screening of cervical disease. The present study evaluated the utility of DSC in differentiating between healthy controls, increasing severity of CIN and early and advanced IC. Significant discrimination was apparent relative to the extent of disease with no clear effect of demographic factors such as age, ethnicity, smoking status and parity. Of most clinical relevance, there was strong differentiation of CIN from healthy controls and IC, and amongst patients with IC between FIGO Stage I and advanced cancer. The observed disease-specific changes in DSC profiles (thermograms) were hypothesized to reflect differential expression of disease biomarkers that subsequently bound to and affected the thermal behavior of the most abundant plasma proteins. The effect of interacting biomarkers can be inferred from the modulation of thermograms but cannot be directly identified by DSC. To investigate the nature of the proposed interactions, mass spectrometry (MS) analyses were employed. Quantitative assessment of the low molecular weight protein fragments of plasma and urine samples revealed a small list of peptides whose abundance was correlated with the extent of cervical disease, with the most striking plasma peptidome data supporting the interactome theory of peptide portioning to abundant plasma proteins. The combined DSC and MS approach in this study was successful in identifying unique biomarker signatures for cervical cancer and demonstrated the utility of DSC plasma profiles as a complementary diagnostic tool to evaluate cervical cancer health. PMID:24416269

  11. 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 (?E) 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 (?), 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 (?T) were determined from Differential Scanning Calorimetry (DSC).

  12. A sample-saving method for heat capacity measurements on powders using relaxation calorimetry

    PubMed Central

    Dachs, Edgar; Benisek, Artur

    2011-01-01

    An experimental method is described for determining the low-temperature heat capacity (Cp) of mg-sized powder samples using the Quantum Design “Physical Properties Measurement System” (PPMS). The powder is contained in an Al pan as an ?1 mm thick compressed layer. The sample is not mixed with Apiezon N grease, as compared to other methods. Thus, it is not contaminated and can be used for further study. This is necessary for samples that are only available in tiny amounts. To demonstrate the method various samples, all insulating in nature, were studied including benzoic acid, sapphire and different silicate minerals. The measurements show that the method has an accuracy in Cp to better than 1% at T above 30–50 K and ±3–5% up to ±10% below. The experimental procedure is based on three independent PPMS and three independent differential scanning calorimetry (DSC) measurements. The DSC Cp data are used to slightly adjust the PPMS Cp data by a factor CpDSC/CpPPMSat298K. This is done because heat capacities measured with a DSC device are more accurate around ambient T (?0.6%) than PPMS values and is possible because the deviation of PPMS heat capacities from reference values is nearly constant between about 50 K and 300 K. The resulting standard entropies agree with published reference values within 0.21% for the silicates, by 0.34% for corundum, and by 0.9% for powdered benzoic acid. The method thus allows entropy determinations on powders with an accuracy of better than 1%. The advantage of our method compared to other experimental techniques is that the sample powder is not contaminated with grease and that heat capacity values show less scatter at high temperatures. PMID:21886915

  13. A sample-saving method for heat capacity measurements on powders using relaxation calorimetry.

    PubMed

    Dachs, Edgar; Benisek, Artur

    2011-08-01

    An experimental method is described for determining the low-temperature heat capacity (C(p)) of mg-sized powder samples using the Quantum Design "Physical Properties Measurement System" (PPMS). The powder is contained in an Al pan as an ?1 mm thick compressed layer. The sample is not mixed with Apiezon N grease, as compared to other methods. Thus, it is not contaminated and can be used for further study. This is necessary for samples that are only available in tiny amounts. To demonstrate the method various samples, all insulating in nature, were studied including benzoic acid, sapphire and different silicate minerals. The measurements show that the method has an accuracy in C(p) to better than 1% at T above 30-50 K and ±3-5% up to ±10% below. The experimental procedure is based on three independent PPMS and three independent differential scanning calorimetry (DSC) measurements. The DSC C(p) data are used to slightly adjust the PPMS C(p) data by a factor CpDSC/CpPPMSat298K. This is done because heat capacities measured with a DSC device are more accurate around ambient T (?0.6%) than PPMS values and is possible because the deviation of PPMS heat capacities from reference values is nearly constant between about 50 K and 300 K. The resulting standard entropies agree with published reference values within 0.21% for the silicates, by 0.34% for corundum, and by 0.9% for powdered benzoic acid. The method thus allows entropy determinations on powders with an accuracy of better than 1%. The advantage of our method compared to other experimental techniques is that the sample powder is not contaminated with grease and that heat capacity values show less scatter at high temperatures. PMID:21886915

  14. DSC study of melting and glass transition in gelatins

    Microsoft Academic Search

    G. I. Tseretely; O. I. Smirnova

    1992-01-01

    In the range from ?50° to +130°C, the temperature dependence of the heat capacity for different kinds of gelatins with water contents of from 2 to 95% was studied by the DSC method. It was shown that, in all studied cases, metastable collagen-like structures are formed in gels or crystalline gelatins, with thermodynamic parameters depending on the formation conditions. The

  15. High temperature drop calorimetry and thermodynamic properties

    SciTech Connect

    Chandrasekhariah, M.S. [Houston Advanced Research Center, The Woodlands, TX (United States). Materials Science Research Center; Bautista, R.G. [Univ. of Nevada, Reno, NV (United States). Dept. of Chemical and Metallurgical Engineering

    1995-04-01

    Experimental determination of thermodynamic properties (e.g. enthalpy of formation, heat capacity, Gibbs free energy, etc.) is still the recourse for accurate thermodynamic data for the condensed phases. Calorimetry is probably the best experimental method for their determination. Drop calorimetry in its various modifications is still the method of choice to determine the enthalpy functions for solids and liquids above 1,000 C. The conventional drop calorimeter for solids and a drop calorimeter coupled to an electromagnetic levitation coil useful for conductive samples in both the solid and molten phases are described. Experimental results obtained up to and above the melting point of rare earth metals are presented.

  16. Investigation on chemical cross-linked collagen phosphoric acid hydrolysates with cyanuric chloride by differential scanning calorimetry

    Microsoft Academic Search

    I. Chakarska; S. Todinova; K. Idakieva

    2010-01-01

    The process of cross-linking of collagen phosphoric acid hydrolysates (CH) with cyanuric chloride (CY) was studied by the\\u000a increase in the denaturation temperature using differential scanning calorimetry (DSC). This measurement gave indications\\u000a concerning the efficiency of the treatment, i.e., the extent of cross-linking of the collagen hydrolysates. The optimal conditions\\u000a for cross-linking were determined: CH\\/CY in a ratio 1:1, reaction

  17. Detection of a new 'nematic-like' phase in liquid crystal-amphiphile mixture by differential scanning calorimetry

    NASA Astrophysics Data System (ADS)

    Dan, Kaustabh; Roy, Madhusudan; Datta, Alokmay

    2014-04-01

    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 (Tc) 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. Detection of a new 'nematic-like' phase in liquid crystal-amphiphile mixture by differential scanning calorimetry

    SciTech Connect

    Dan, Kaustabh, E-mail: kaustabhdan@gmail.com; Roy, Madhusudan, E-mail: kaustabhdan@gmail.com; Datta, Alokmay, E-mail: kaustabhdan@gmail.com [Surface Physics and Materials Science Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar Block, Sector 1, Kolkata-700064 (India)

    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.

  19. 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)

  20. 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.

  1. DSC study on carbide precipitation reaction in Inconel 600

    NASA Astrophysics Data System (ADS)

    Park, J. M.; Ryu, W. S.; Kang, Y. H.

    1994-05-01

    The carbide precipitation process in Inconel 600 alloy was systematically investigated to understand the reaction mechanism by measuring the carbide reaction peaks, activation energies and microstructures using DSC and TEM. At the initial stage, the fine and sparse carbide begins to precipitate only at grain boundaries, and thereafter grows into a layered structure with additional precipitation of fine intragranular carbides near grain boundary region in the form of M 7C 3 type. For solution-annealed specimens the thin and continuous intergranular carbide precititates at 550°C with an activation energy of 33 kcal/mol, related with the rate-limiting step of carbon diffusion in the matrix. However, for solution-annealed followed by cold-worked Inconel 600, the DSC peak temperature for carbide precipitation is lowered to 350°C with an apparent activation energy of 20 kcal/mol, associated with the carbide formation caused by the carbon diffusion through defects such as grain boundary and dislocation.

  2. DSC3 expression is regulated by p53, and methylation of DSC3 DNA is a prognostic marker in human colorectal cancer

    PubMed Central

    Cui, T; Chen, Y; Yang, L; Knösel, T; Zöller, K; Huber, O; Petersen, I

    2011-01-01

    Background: Desmocollin 3 (DSC3), a member of the cadherin superfamily and integral component of desmosomes, is involved in carcinogenesis. However, the role of DSC3 in colorectal cancer (CRC) has not yet been established. Methods: Desmocollin 3 expression in CRC cell lines was analysed by RT–PCR and western blotting. Methylation status of DSC3 was examined by demethylation tests, methylation-specific PCR, and bisulphite sequencing (BS). The regulatory role of p53 was investigated by transfection. Results: Desmocollin 3 was downregulated in CRC cells at mRNA and protein levels. Desmocollin 3 expression was restored in five out of seven cell lines after 5-aza-2?-deoxycytidine (DAC) treatment. A heterogeneous methylation pattern was detected by BS in promoter region and exon 1 of DSC3. Methylation of DSC3 genomic sequences was found in 41% (41 out of 99) of primary CRC, being associated with poor prognosis (P=0.002). Transfection of p53 alone or in combination of DAC increased the DSC3 expression. Similarly, treatment with p53 inducer adriamycin alone or in combination with DAC enhanced DSC3 expression. Conclusions: DNA methylation contributes to downregulation of DSC3 in CRC cell lines. Methylation status of DSC3 DNA is a prognostic marker for CRC. P53 appears to have an important role in regulating DSC3 expression. PMID:21364582

  3. Dsc orthologs are required for hypoxia adaptation, triazole drug responses, and fungal virulence in Aspergillus fumigatus.

    PubMed

    Willger, Sven D; Cornish, E Jean; Chung, Dawoon; Fleming, Brittany A; Lehmann, Margaret M; Puttikamonkul, Srisombat; Cramer, Robert A

    2012-12-01

    Hypoxia is an environmental stress encountered by Aspergillus fumigatus during invasive pulmonary aspergillosis (IPA). The ability of this mold to adapt to hypoxia is important for fungal virulence and genetically regulated in part by the sterol regulatory element binding protein (SREBP) SrbA. SrbA is required for fungal growth in the murine lung and to ultimately cause lethal disease in murine models of IPA. Here we identified and partially characterized four genes (dscA, dscB, dscC, and dscD, here referred to as dscA-D) with previously unknown functions in A. fumigatus that are orthologs of the Schizosaccharomyces pombe genes dsc1, dsc2, dsc3, and dsc4 (dsc1-4), which encode a Golgi E3 ligase complex critical for SREBP activation by proteolytic cleavage. A. fumigatus null dscA-D mutants displayed remarkable defects in hypoxic growth and increased susceptibility to triazole antifungal drugs. Consistent with the confirmed role of these genes in S. pombe, both ?dscA and ?dscC resulted in reduced cleavage of the SrbA precursor protein in A. fumigatus. Inoculation of corticosteroid immunosuppressed mice with ?dscA and ?dscC strains revealed that these genes are critical for A. fumigatus virulence. Reintroduction of SrbA amino acids 1 to 425, encompassing the N terminus DNA binding domain, into the ?dscA strain was able to partially restore virulence, further supporting a mechanistic link between DscA and SrbA function. Thus, we have shown for the first time the importance of a previously uncharacterized group of genes in A. fumigatus that mediate hypoxia adaptation, fungal virulence, and triazole drug susceptibility and that are likely linked to regulation of SrbA function. PMID:23104569

  4. Dsc Orthologs Are Required for Hypoxia Adaptation, Triazole Drug Responses, and Fungal Virulence in Aspergillus fumigatus

    PubMed Central

    Willger, Sven D.; Cornish, E. Jean; Chung, Dawoon; Fleming, Brittany A.; Lehmann, Margaret M.; Puttikamonkul, Srisombat

    2012-01-01

    Hypoxia is an environmental stress encountered by Aspergillus fumigatus during invasive pulmonary aspergillosis (IPA). The ability of this mold to adapt to hypoxia is important for fungal virulence and genetically regulated in part by the sterol regulatory element binding protein (SREBP) SrbA. SrbA is required for fungal growth in the murine lung and to ultimately cause lethal disease in murine models of IPA. Here we identified and partially characterized four genes (dscA, dscB, dscC, and dscD, here referred to as dscA-D) with previously unknown functions in A. fumigatus that are orthologs of the Schizosaccharomyces pombe genes dsc1, dsc2, dsc3, and dsc4 (dsc1-4), which encode a Golgi E3 ligase complex critical for SREBP activation by proteolytic cleavage. A. fumigatus null dscA-D mutants displayed remarkable defects in hypoxic growth and increased susceptibility to triazole antifungal drugs. Consistent with the confirmed role of these genes in S. pombe, both ?dscA and ?dscC resulted in reduced cleavage of the SrbA precursor protein in A. fumigatus. Inoculation of corticosteroid immunosuppressed mice with ?dscA and ?dscC strains revealed that these genes are critical for A. fumigatus virulence. Reintroduction of SrbA amino acids 1 to 425, encompassing the N terminus DNA binding domain, into the ?dscA strain was able to partially restore virulence, further supporting a mechanistic link between DscA and SrbA function. Thus, we have shown for the first time the importance of a previously uncharacterized group of genes in A. fumigatus that mediate hypoxia adaptation, fungal virulence, and triazole drug susceptibility and that are likely linked to regulation of SrbA function. PMID:23104569

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

    NASA Astrophysics Data System (ADS)

    Migda?-Mikuli, Anna; Skoczylas, ?ukasz; Szostak, El?bieta

    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 T?C4 = (328±2) K, metastable KIII ? undercooled phase K0 at T?C3 = (383±4) K, metastable KII ? undercooled K0 at T?C2 = (399±2) K and stable KIa ? stable K0 at T?C1 = (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

  6. 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. PMID:25561411

  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 larger part of the total BC amount in agricultural soils compared to forest soils, suggesting that cultivation might accelerate charcoal degradation. Regarding the K2Cr2O7 oxidation, 65 % of the TOC is oxidized in forest soils while 100 % is oxidized in agricultural soils, discrediting the method for old charcoal quantification in soil. In conclusion, DSC is a rapid and cost-effective technique for BC quantification in soil, covering the entire range of the BC continuum while giving information on the thermal stability of different BC pools. Oppositely, K2Cr2O7 oxidation in not a suitable method for old charcoal quantification in soil.

  8. Influence of containing moisture on hydrothermal stability of modified collagen thermal characteristics analysis by DSC

    Microsoft Academic Search

    Ya-juan Wang; Jun Guo; Hui Chen; Zhi-hua Shan

    2010-01-01

    The thermal stability of sheepskin collagen cross-linked with chrome sulfate and mimosa (MI)–oxazolidine (OZ), respectively,\\u000a had been researched in this experiment. All samples’ shrinkage temperatures (T\\u000a s) are determined by a special T\\u000a s-testing-apparatus and denaturation temperatures (T\\u000a d) are determined by the differential scanning calorimetry. The relations between the modified collagens containing moisture\\u000a and their hydrothermal stability, T\\u000a s

  9. 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. PMID:20307976

  10. 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

    2014-08-01

    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. PMID:24751240

  11. 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 ? = 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.

  12. CDF (Collider Detector at Fermilab) calorimetry

    SciTech Connect

    Jensen, H.B.

    1987-03-01

    The Collider Detector at Fermilab (CDF) is a large detector built to study 2 TeV anti p p collisions at the Fermilab Tevatron. The calorimetry, which has polar angle coverage from 2 to 178, and complete azimuthal coverage within this region, forms the subject of this paper. It consists of both electromagnetic shower counters (EM calorimeters) and hadron calorimeters, and is segmented into about 5000 ''towers'' or solid angle elements.

  13. Secondary Emission Ionization Calorimetry R&D

    NASA Astrophysics Data System (ADS)

    Tiras, Emrah

    2014-03-01

    Secondary Emission (SE) Calorimetry is a new promising technique to measure the electromagnetic showers in extreme radiation environment and very high rate. In this detector type, SE dynode planes are used as the active medium where the SE electrons are generated from these SE surfaces when charged particles penetrate an SE sampling module. Here we report on the response of a dedicated SE sampling module in electromagnetic showers. Projections for a full-scale calorimeter will also be discussed.

  14. Investigation of MSWI fly ash melting characteristic by DSC-DTA

    SciTech Connect

    Li, Rundong [Institute of Clean Energy and Environmental Engineering, Liaoning Key Laboratory of Clean Energy, Shenyang Institute of Aeronautical Engineering, Shenyang 110136 (China)], E-mail: leerd@mail.tsinghua.edu.cn; Wang, Lei; Yang, Tianhua; Raninger, Bernhard [Institute of Clean Energy and Environmental Engineering, Liaoning Key Laboratory of Clean Energy, Shenyang Institute of Aeronautical Engineering, Shenyang 110136 (China)

    2007-07-01

    The melting process of MSWI (Municipal Solid Waste Incineration) fly ash has been studied by high-temperature DSC-DTA experiments. The experiments were performed at a temperature range of 20-1450 deg. C, and the considerable variables included atmosphere (O{sub 2} and N{sub 2}), heating rates (5 deg. C/min, 10 deg. C/min, 20 deg. C/min) and CaO addition. Three main transitions were observed during the melting process of fly ash: dehydration, polymorphic transition and fusion, occurring in the temperature range of 100-200 deg. C, 480-670 deg. C and 1101-1244 deg. C, respectively. The apparent heat capacity and heat requirement for melting of MSWI fly ash were obtained by DSC (Differential Scanning Calorimeter). A thermodynamic modeling to predict the heat requirements for melting process has been presented, and it agrees well with the experimental data. Finally, a zero-order kinetic model of fly ash melting transition was established. The apparent activation energy of MSWI fly ash melting transition was obtained.

  15. 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. PMID:12359088

  16. A sample-saving method for heat capacity measurements on powders using relaxation calorimetry

    NASA Astrophysics Data System (ADS)

    Dachs, Edgar; Benisek, Artur

    2011-08-01

    An experimental method is described for determining the low-temperature heat capacity (Cp) of mg-sized powder samples using the Quantum Design “Physical Properties Measurement System” (PPMS). The powder is contained in an Al pan as an ?1 mm thick compressed layer. The sample is not mixed with Apiezon N grease, as compared to other methods. Thus, it is not contaminated and can be used for further study. This is necessary for samples that are only available in tiny amounts. To demonstrate the method various samples, all insulating in nature, were studied including benzoic acid, sapphire and different silicate minerals. The measurements show that the method has an accuracy in Cp to better than 1% at T above 30-50 K and ±3-5% up to ±10% below. The experimental procedure is based on three independent PPMS and three independent differential scanning calorimetry (DSC) measurements. The DSC Cp data are used to slightly adjust the PPMS Cp data by a factor C. This is done because heat capacities measured with a DSC device are more accurate around ambient T (?0.6%) than PPMS values and is possible because the deviation of PPMS heat capacities from reference values is nearly constant between about 50 K and 300 K. The resulting standard entropies agree with published reference values within 0.21% for the silicates, by 0.34% for corundum, and by 0.9% for powdered benzoic acid. The method thus allows entropy determinations on powders with an accuracy of better than 1%. The advantage of our method compared to other experimental techniques is that the sample powder is not contaminated with grease and that heat capacity values show less scatter at high temperatures.

  17. A rapid micro quantification method of paracetamol in suppositories using differential scanning calorimetry.

    PubMed

    Noordin, Mohamed I; Chung, L Y

    2004-01-01

    This study adopts Differential Scanning Calorimetry (DSC) to analyze the thermal properties of samples (2.5-4.0 mg) from the tip, middle, and base sections of individual paracetamol suppositories, which were sampled carefully using a stainless steel scalpel. The contents of paracetamol present in the samples obtained from these sections were determined from the enthalpies of fusion of paracetamol and expressed as % w/w paracetamol to allow comparison of the amount of paracetamol found in each section. The tip, middle, and base sections contained 10.1+/-0.2%, 10.1+/-0.2%, and 10.3+/-0.2% w/w paracetamol, and are statistically similar (One-way anova; p>0.05). This indicates that the preparation technique adopted produces high quality suppositories in terms of content uniformity. The contents of paracetamol in the 120-mg paracetamol suppositories determined by DSC and UV spectrophotometry were statistically equivalent (Students's t-test; p>0.05), 120.8+/-2.6 mg and 120.8+/-1.5 mg, respectively, making DSC a clear alternative method for the measurement of content of drug in suppositories. The main advantages of the method are that samples of only 2.5-4.0 mg are required and the procedure does not require an extraction process, which allows for the analysis to be completed rapidly. In addition, it is highly sensitive and reproducible, with the lower detection limit at 4.0% w/w paracetamol, which is about 2.5 times lower than the content of paracetamol (10% w/w) present in our 120-mg paracetamol suppositories and commercial paracetamol suppositories, which contained about 125 mg paracetamol. Therefore, this method is particularly suited for determination of content uniformity in individual suppositories in quality control (QC) and in process quality control (PQC). PMID:15554216

  18. Characterization of non-crystalline phases of LLDPE`s using calorimetry to strain the samples

    NASA Astrophysics Data System (ADS)

    Phuong-Nguyen, Hong; Jedidi, Ilyes; Chola, Fabien; Delmas, Genevieve

    2004-03-01

    The non-crystalline phases of a semi-crystalline polymer contribute to the sample properties but they are difficult to characterize. We have been investigating the network or entangled phase of polyethylenes by slow calorimetry and FTIR. Differences in the arrangement of tie molecules and semi-ordered regions in this phase are at the origin of specific processing characteristics of Metallocene (MT)- and Ziegler Natta (ZN)- catalysed LLDPE samples. However, little difference at RT has been revealed by 13C NMR or FTIR for ZN and MT. In this work, we explore the in-situ response of the entangled phase to a strained situation, assuming that it could reveal differences not seen in an equilibrium situation. Using the rate of heating v, and the sample mass m, to control strain, we observe specific traces for ZN and MT and also the effect of aging. The two techniques are slow calorimetry (I) (v = 0.02 K/min, m= 20-30 mg) and DSC (II) (v= 0.5 K/min, m=1-2 mg) ). In (I), large endotherms are observed in the melt and in (II), a succession of fusion/ recrystallization/ fusion. Organizations with less order than the orthorhombic crystals (extended crystals, pseudo-hexagonal phase) can grow in conditions of heating which accommodate their slow kinetics of formation. Patterns in (I) and (II) are seen to be catalyst-dependant.

  19. Characterization of supercooled liquid Ge2Sb2Te5 and its crystallization by ultrafast-heating calorimetry.

    PubMed

    Orava, J; Greer, A L; Gholipour, B; Hewak, D W; Smith, C E

    2012-04-01

    Differential scanning calorimetry (DSC) is widely used to study the stability of amorphous solids, characterizing the kinetics of crystallization close to the glass-transition temperature T(g). We apply ultrafast DSC to the phase-change material Ge(2)Sb(2)Te(5) (GST) and show that if the range of heating rates is extended to more than 10(4) K s(-1), the analysis can cover a wider temperature range, up to the point where the crystal growth rate approaches its maximum. The growth rates that can be characterized are some four orders of magnitude higher than in conventional DSC, reaching values relevant for the application of GST as a data-storage medium. The kinetic coefficient for crystal growth has a strongly non-Arrhenius temperature dependence, revealing that supercooled liquid GST has a high fragility. Near T(g) there is evidence for decoupling of the crystal-growth kinetics from viscous flow, matching the behaviour for a fragile liquid suggested by studies on oxide and organic systems. PMID:22426461

  20. Characterization of supercooled liquid Ge2Sb2Te5 and its crystallization by ultrafast-heating calorimetry

    NASA Astrophysics Data System (ADS)

    Orava, J.; Greer, A. L.; Gholipour, B.; Hewak, D. W.; Smith, C. E.

    2012-04-01

    Differential scanning calorimetry (DSC) is widely used to study the stability of amorphous solids, characterizing the kinetics of crystallization close to the glass-transition temperature Tg. We apply ultrafast DSC to the phase-change material Ge2Sb2Te5 (GST) and show that if the range of heating rates is extended to more than 104?K?s-1, the analysis can cover a wider temperature range, up to the point where the crystal growth rate approaches its maximum. The growth rates that can be characterized are some four orders of magnitude higher than in conventional DSC, reaching values relevant for the application of GST as a data-storage medium. The kinetic coefficient for crystal growth has a strongly non-Arrhenius temperature dependence, revealing that supercooled liquid GST has a high fragility. Near Tg there is evidence for decoupling of the crystal-growth kinetics from viscous flow, matching the behaviour for a fragile liquid suggested by studies on oxide and organic systems.

  1. A differential scanning calorimetry analysis of the age-related changes in the thermal stability of rat skin collagen.

    PubMed

    Flandin, F; Buffevant, C; Herbage, D

    1984-12-01

    Differential scanning calorimetry (DSC) has been applied to the study of connective tissue to evaluate the denaturation process of collagen. We have applied this technique to the study of the ageing of rat skin. We have tried to correlate the variations of the parameters measured by DSC and the modifications of collagen crosslinks with ageing. The thermograms obtained are composed of one main peak located between two shoulders. The relative size of each peak varies with time: the first peak diminishes regularly from 2 to 20 months whilst, at the same time, the third peak increases; the recovery temperature increases with age (+ 16 degrees C between 2 and 20 months); the total denaturation enthalpy does not vary: the main value obtained is 5.9 X 10(-2) J/mg collagen. On the other hand, the assay of reducible collagen crosslinks in rat skin, over the same age range, shows a decrease of heat-labile aldimine crosslink (essentially hydroxylysinonorleucine). These results and the study of thermograms obtained with altered rat skin (animals treated with beta-aminopropionitrile or skin reduced with NaBH4) allow us to conclude that heat-labile and heat-stable crosslinks account for a collagen thermal stabilization which can explain the delay of denaturation characterized by the third peak of DSC thermograms. PMID:6509063

  2. 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 ?Hm 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. PMID:25037100

  3. Profiles in Leadership: Clifton J. Latiolais, MSc, DSc

    PubMed Central

    White, Sara; Godwin, Harold N.; 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 marks the 50th anniversary of the publication of the Mirror to Hospital Pharmacy, which was a comprehensive study of pharmacy services in the United States. The late Clifton J. Latiolais, MS, DSc, served as the assistant program director for the study and was a co-author of the Mirror. The late Don E. Francke, MS, DSc, was the lead author of the Mirror and the principal investigator of the federally funded study that reviewed hospital pharmacy services across the United States. The next 2 articles in Director’s Forum profile the leadership of Drs. Latiolais and Francke. This article highlights Dr. Latiolais (“Clif”) by briefly reviewing his biography and key career accomplishments, describing his leadership philosophy, and translating that philosophy to today’s health care challenges. Clif’s influence on health system pharmacy serves as an example of effective leadership. This historical perspective on Clif’s leadership, as seen through the eyes of those who knew him, provides directors of pharmacy a valuable leadership viewpoint as they develop strategies to enhance patient-centered pharmacy services. PMID:24421540

  4. Prospects for and tests of hadron calorimetry with silicon

    SciTech Connect

    Brau, James E. [Univ. of Oregon, OR (United States). Dept. of Physics] [Univ. of Oregon, OR (United States). Dept. of Physics; Gabriel, Tony A. [Oak Ridge National Lab., TN (United States)] [Oak Ridge National Lab., TN (United States); Rancoita, P. G. [INFN, Milan (Italy)] [INFN, Milan (Italy)

    1989-03-01

    Hadron calorimetry with silicon may provide crucial capabilities in experiments at the high luminosity, high energy colliders of the future, particularly due to silicon's fast intrinsic speed and absolute calibration. The important underlying processes of our understanding of hadron calorimeters 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, the ratio of the most probable electron signal to hadron signal (e/h) is 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. An experimental test of these predictions is underway at CERN by the SICAPO Collaboration. 64 refs., 19 figs.

  5. Evaluation Of The Kinetics Of Crystallization in Aluminum Fluoride Glass Using Isothermal DSC Method

    NASA Astrophysics Data System (ADS)

    Marzuki, Ahmad

    2010-12-01

    This paper reports the isothermal differential scanning calorimeter (DSC) method used to study the crystallization kinetics of aluminum fluoride glass. The effective activation energy of crystallization (?Ea/n) was evaluated from the DSC curves using the Johnson-Mehl-Avrami equation. The value of the effective activation energy (Ea/n = 113.3 kJ/mol) found from the isothermal DSC curves was slightly higher than that obtained previously with the non-isothermal DSC method (?Ec/n = 108.1 kJ/mol). It turns out that both methods can be used in this case.

  6. Synergies between electromagnetic calorimetry and PET

    SciTech Connect

    Moses, William W.

    2002-07-30

    The instrumentation used for the nuclear medical imaging technique of Positron Emission Tomography (PET) shares many features with the instrumentation used for electromagnetic calorimetry. Both fields can certainly benefit from technical advances in many common areas, and this paper discusses both the commonalties and the differences between the instrumentation needs for the two fields. The overall aim is to identify where synergistic development opportunities exist. While such opportunities exist in inorganic scintillators, photodetectors, amplification and readout electronics, and high-speed computing, it is important to recognize that while the requirements of the two fields are similar, they are not identical, and so it is unlikely that advances specific to one field can be transferred without modification to the other.

  7. Calorimetry for Fast Authentication of Edible Oils

    NASA Astrophysics Data System (ADS)

    Angiuli, Marco; Bussolino, Gian Carlo; Ferrari, Carlo; Matteoli, Enrico; Righetti, Maria Cristina; Salvetti, Giuseppe; Tombari, Elpidio

    2009-06-01

    There are little data in the literature on how to authenticate edible oils through calorimetry techniques. However, oil melting curves can be used to represent correlations between calorimetric results and oil quality. A calorimetric method has been developed for studying the solid-liquid phase transitions of olive oil and seed oils, in which melting peak behavior is correlated to the type, quality, and composition of the oil. Good reproducible thermograms were obtained by defining precise protocols for use in testing, which take into account the specific characteristics of a particular oil. This approach does not replace classical analytical methods; nevertheless, it is believed that calorimetric tests could be a useful preliminary stage for quality testing. The calorimetric technique allows the detection of the adulterant (seed oils or refined olive oil), oil origin, and possible photo-oxidation degradation processes, before more complex and expensive procedures and analyses are applied.

  8. Isothermal titration calorimetry in drug discovery.

    PubMed

    Ward, W H; Holdgate, G A

    2001-01-01

    Isothermal titration calorimetry (ITC) follows the heat change when a test compound binds to a target protein. It allows precise measurement of affinity. The method is direct, making interpretation facile, because there is no requirement for competing molecules. Titration in the presence of other ligands rapidly provides information on the mechanism of action of the test compound, identifying the intermolecular complexes that are relevant for structure-based design. Calorimetry allows measurement of stoichiometry and so evaluation of the proportion of the sample that is functional. ITC can characterize protein fragments and catalytically inactive mutant enzymes. It is the only technique which directly measures the enthalpy of binding (delta H degree). Interpretation of delta H degree and its temperature dependence (delta Cp) is usually qualitative, not quantitative. This is because of complicated contributions from linked equilibria and a single change in structure giving modification of several physicochemical properties. Measured delta H degree values allow characterization of proton movement linked to the association of protein and ligand, giving information on the ionization of groups involved in binding. Biochemical systems characteristically exhibit enthalpy-entropy compensation where increased bonding is offset by an entropic penalty, reducing the magnitude of change in affinity. This also causes a lack of correlation between the free energy of binding (delta G degree) and delta H degree. When characterizing structure-activity relationships (SAR), most groups involved in binding can be detected as contributing to delta H degree, but not to affinity. Large enthalpy changes may reflect a modified binding mode, or protein conformation changes. Thus, delta H degree values may highlight a potential discontinuity in SAR, so that experimental structural data are likely to be particularly valuable in molecular design. PMID:11774798

  9. 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 (200-350 C - nominally ‘labile’/low MW, 350-500 C - increasing recalcitrance/MW and 500-650 C - recalcitrant/high MW). Samples from all three systems show similar stability distributions with broader less resolved peaks for DOC and soil with intense more resolved peaks for mature compost. DOC flocculated with Iron (Fe) or aluminum (Al) broadened and shifted peak stability to higher temps doubling energy yield compared to DOC (least complex most change). Fe and Al oxides added during composting broadened peaks with shifts towards higher temps with more modest increases in energetic yield(increased complexity reduced change). Soils illustrate a broad and balanced distribution that is fairly robust to treatment or input (most complex least change). Generally metal oxides increased thermal stability and system complexity altering stability distributions towards the diverse and complex soil system. Is the complex and attenuating nature of soil the benchmark to quantify less stable and complex systems based on their components, alterations and metrics of thermal stability and order? Our research is an initial test of this idea supported by reproducible thermal metrics to assess the attenuation of C through natural systems.

  10. 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.

  11. Magnetic phase transition in valence tautomers as polymorphs of 3-iodolawsone: Single crystal X-ray structure, DSC and EPR studies

    NASA Astrophysics Data System (ADS)

    Zaware, Santosh B.; Dagade-Waghmode, Shobha; Gonnade, Rajesh G.; Srinivas, Darbha; Rane, Sandhya Y.

    2009-12-01

    Three polymorphs of 3-iodolawsone ( I- III) have been isolated and characterized by single crystal X-ray diffraction, electron paramagnetic resonance (EPR) spectroscopy and differential scanning calorimetry (DSC) techniques. Polymorphs I and II were crystallized from methanol in two different valence tautomeric forms: hydroxynaphthoquinone (HNQ) and hydroxynaphthosemiquinone (HNSQ) as needles and thick plates, respectively. Polymorph III was crystallized from ethanol in HNQ form, as thin plates. Chiral crystals of I belongs to the orthorhombic P2 12 12 1 space group; II and III belong to the monoclinic non-centrosymmetric space group Cc. The molecules are packed via O sbnd H⋯O bonding and ?⋯? stacking interactions. The study reveals that relatively stronger intermolecular H-bonding (2.02 Å) and most favoured ?⋯? stacking (˜3.49 Å) interactions lead II to HNSQ radicals, presence of which was confirmed by EPR ( g = 2.0052) spectroscopy. Interestingly, these materials exhibit crystal-to-crystal magnetic phase transition from polymorph I (diamagnetic) to polymorph II (paramagnetic structure) at 171.1 °C as identified by DSC and X-ray crystallographic studies.

  12. The suitability of DSC method for damage assessment and certification of historical leathers and parchments

    Microsoft Academic Search

    Petru Budrugeac; Lucre?ia Miu

    2008-01-01

    The DSC analysis was used for investigation of thermal behaviour in water and nitrogen, oxygen and synthetic airflow of some collagen-based materials (pure collagen, recent manufactured (new) parchments and tanned leathers, and historical (old) parchments and leathers).The shrinkage temperature values (Ts) of the investigated materials, determined by DSC analysis of the samples immersed in water, are in good agreement with

  13. 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

    2015-08-20

    Gluten-free flour doughs (three from different maize varieties and one from chestnut fruit) processed at the same consistency level (1.10±0.07Nm) 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. PMID:25965469

  14. 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.

  15. DSC Study on Cooperative Relaxation in 1,2-propanediol

    NASA Astrophysics Data System (ADS)

    Gao, Cai; Wang, Tie-jun; Liu, Xiang-nong; Zhou, Guo-yan; Hua, Tse-chao

    2007-06-01

    Cooling rate dependence of the cooperative relaxation in 1,2-propanediol was investigated in terms of the nonlinear Adam-Gibbs (AG) enthalpy relaxation theory using differential scanning calorimetry. The AG parameters were obtained using a curve-fitting method. The results indicated that the model parameters show strong dependence on the cooling rates. Those obtained at higher cooling rates are in good agreement with the published data. The fitting results were used to estimate the microscopic parameters of the cooperative rearranging region (CRR), in particular the size of the CRR (z*) and the configurational state available to it (W*). It was found that the W* recommended for polymers led to physically meaningless z* for 1,2-propanediol. Johari's method, which was based on the AG theory, yielded around 3 molecules in the CRR, but the W* was anomalistically higher than those of polymers. It is difficult to reconcile the Adam-Gibbs' z* with the results obtained using Donth's formula. An argument is presented that a new physical meaning should be given to conventional Adam-Gibbs' z* for molecular H-bond liquids.

  16. Hadron sampling calorimetry, a puzzle of physics

    NASA Astrophysics Data System (ADS)

    Brückmann, Hanno; Anders, Bernd; Behrens, Ulf

    1988-01-01

    The physics involved in hadron sampling calorimetry covers the wide energy range between high energy, medium energy, nuclear and atomic physics. All the processes contributing to energy depositions are discussed as well as illustrated by model calculations. The sampling fraction which determines the fraction of incident energy, which becomes visible in the detector layers, turns out to be strongly affected by the type of energy flow and the atomic number Z of the materials used. Normalized to mips, such fractions might range in the examples discussed between 0 and 2. Model calculations have been based on the HERMES scheme, which makes use of improved versions of the HET, the MORSE and the new developed DYMO code. The results allow to evaluate the degree of compensation and to predict e/h ratios. Such predictions agree quite well with the experimental results. In case of depleted uranium/scintillator sampling structures, compensation can be tuned by means of layer thicknesses. Finally, first results are presented for the investigation of fluctuations and correlations from model calculations evaluated event-by-event.

  17. Particle Flow Calorimetry at the ILC

    NASA Astrophysics Data System (ADS)

    Brost, Elizabeth C.; Wanotayaroj, Chaowaroj; Brau, James E.

    2011-10-01

    The Silicon Detector (SiD) concept is under development for the International Linear Collider (ILC). SiD is designed for high-precision measurements of electron-positron collisions at the ILC for center of mass energies up to 1 TeV, addressing fundamental questions of particle physics, including the mechanism responsible for electroweak symmetry breaking and the generation of mass, the unification of forces, the structure of space-time at short distances, and connections with cosmology. These studies require excellent jet energy resolution. SiD features a finely-segmented silicon-tungsten electromagnetic calorimeter (ECAL) and a multi-layer steel with resistive plate chambers (RPC) hadron calorimeter (HCAL), in a design optimized for Particle Flow Calorimetry. The Particle Flow Algorithm (PFA) uses energy measurements of charged particles in the tracker and separated calorimeter hits from neutral particles, in order to achieve the best possible jet energy resolution. We present studies of energy measurement and particle identification in the ECAL and HCAL investigating improvements in the SiD PFA.

  18. Preparation and transformation of true nifedipine polymorphs: investigated with differential scanning calorimetry and X-Ray diffraction pattern fitting methods.

    PubMed

    Grooff, Driekus; Liebenberg, Wilna; De Villiers, Melgardt M

    2011-05-01

    The amorphous ? metastable and metastable ? stable crystalline phase transitions of nifedipine and their relationship with polymorph composition during storage at controlled temperature/humidity conditions were investigated. Metastable form C was produced from both differential scanning calorimetry (DSC) thermal treatment and storage [22 °C/0% and 75% relative humidity (RH)] of the amorphous form. Amorphous conversion rate accelerated with storage temperature up to 40 °C, but a further 8 °C increase to 48 °C (3 °C above the glass transition) resulted in a more than 12-fold decrease in amorphous conversion rate. DSC and X-Ray diffraction (XRD) analysis revealed a faster amorphous conversion rate relative to the metastable crystal transformation with 75% RH having a greater accelerative effect on the former. Relative phase quantification from XRD pattern fitting included the use of integrated peak intensities of the crystalline phases, Rietveld and the Rietveld-based partial or no known crystal structures method. Kinetic analysis with Johnson-Mehl-Avrami equation indicated that the accelerated amorphous conversion in 75% RH was associated with a 10-fold increase in rate constant with dimensional growth little affected. The smaller rate increase for metastable crystal conversion was associated with an increased dimensional growth while the rate constant was little affected. PMID:21259235

  19. 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 ?(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 (?(max)) at different pH conditions. Marked decreases in T(d) and enthalpy (?H) were observed at extreme alkaline and/or acidic pH, whereas the presence of NaCl resulted in higher T(d) and ?H, along with greater cooperativity of the transition. Decreases in T(d) and ?H 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 ?H) and the ?(max) was observed for KPI in the presence of 0-6 M urea. PMID:21126074

  20. 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 %C2%B0C very little oxidation took place; at 850 %C2%B0C oxidation occurred after an induction period, while at 950 %C2%B0C oxidation occurred without an induction period. At oxidation temperatures between 1050 and 1150 %C2%B0C rapid passivation of the surface of the aluminum foil occurred, while at 1250 %C2%B0C 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.

  1. Differential scanning calorimetry, biochemical, and biomechanical analysis of human skin from individuals with diabetes mellitus.

    PubMed

    Melling, M; Pfeiler, W; Karimian-Teherani, D; Schnallinger, M; Sobal, G; Zangerle, C; Menzel, E J

    2000-07-01

    The aim of this work was to compare biochemical, two-dimensional biomechanical and calorimetric parameters of diabetic skin vs. control skin. Skin specimens taken from the palms and backs of the hands of aged persons with non-insulin-dependent diabetes mellitus (NIDDM) and of controls (CO) were compared (age range 68-85 years). Only skin specimens from individuals with diabetes mellitus (DM) showed an increased fluorescence specific for the formation of advanced glycation end-products (AGEs) and the presence of tissue AGEs, such as N(e)-(Carboxymethyl)lysine (CML). Differential scanning calorimetry (DSC) revealed an elevation of the heat flow per unit mass during collagen denaturation in diabetic skin samples. However, the temperatures of the heat flow maximum and the onset of the phase transformation were not uniformly altered. Young's moduli were found to be increased in diabetic skin and correlated with AGE-fluorescence and tissue AGEs. The ratio between the Young's moduli, which defines a measure for the degree of anisotropy, was higher for dorsal skins from hands. In dorsal skin specimens from diabetic subjects the degree of anisotropy was more pronounced than in healthy controls. In general, neither of the measured parameters showed any correlation with age. However, E(1) moduli were clearly associated with the duration of diabetes. PMID:10861365

  2. Structure of water in mesoporous organosilica by calorimetry and inelastic neutron scattering

    SciTech Connect

    Levy, Esthy [Institute of Nanotechnology Bar-Ilan University, Ramat-Gan, Israel; Kolesnikov, Alexander I [ORNL; Li, Jichen [University of Manchester, UK; Mastai, Yitzhak [Institute of Nanotechnology Bar-Ilan University, Ramat-Gan, Israel

    2009-01-01

    In this paper, we describe the preparation of mesoporous organosilica samples with hydrophilic or hydrophobic organic functionality inside the silica channel. We synthesized mesoporous organosilica of identical pore sizes based on two different organic surface functionality namely hydrophobic (based on octyltriethoxysilane OTES) and hydrophilic (3-aminopropyltriethoxysilane ATES) and MCM-41 was used as a reference system. The structure of water/ice in those porous silica samples have been investigated over a range temperatures by differential scanning calorimetry (DSC) and inelastic neutron scattering (INS). INS study revealed that water confined in hydrophobic mesoporous organosilica shows vibrational behavior strongly different than bulk water. It consists of two states: water with strong and weak hydrogen bonds (with ratio 1:2.65, respectively), compared to ice-Ih. The corresponding O-O distances in these water states are 2.67 and 2.87 ?, which strongly differ compared to ice-Ih (2.76 ?). INS spectra for water in hydrophilic mesoporous organosilica ATES show behavior similar to bulk water, but with greater degree of disorder.

  3. Microphase separation in copolymers of hydrophilic PEG blocks and hydrophobic tyrosine-derived segments using simultaneous SAXS/WAXS/DSC

    SciTech Connect

    Murthy, N.S.; Wang, W.; Kohn, J. (Rutgers); (Vermont)

    2010-10-22

    Hydration- and temperature-induced microphase separations were investigated by simultaneous small- and wide-angle X-ray scattering (SAXS and WAXS) and differential scanning calorimetry (DSC) in a family of copolymers in which hydrophilic poly(ethylene glycol) (PEG) blocks are inserted randomly into a hydrophobic polymer made of either desaminotyrosyl-tyrosine ethyl ester (DTE) or iodinated I{sub 2}DTE segments. Iodination of the tyrosine rings in I{sub 2}DTE increased the X-ray contrast between the hydrophobic and hydrophilic segments in addition to facilitating the study of the effect of iodination on microphase separation. The formation of phase-separated, hydrated PEG domains is of considerable significance as it profoundly affects the polymer properties. The copolymers of DTE (or I{sub 2}DTE) and PEG are a useful model system, and the findings presented here may be applicable to other PEG-containing random copolymers. In copolymers of PEG and DTE and I{sub 2}DTE, the presence of PEG depressed the glass transition temperature (T{sub g}) of the copolymer relative to the homopolymer, poly(DTE carbonate), and the DTE/I{sub 2}DTE segments hindered the crystallization of the PEG segments. In the dry state, at large PEG fractions (>70 vol%), the PEG domains self-assembled into an ordered structure with 14-18 nm distance between the domains. These domains gave rise to a SAXS peak at all temperatures in the iodinated polymers, but only above the T{sub g} in non-iodinated polymers, due to the unexpected contrast-match between the crystalline PEG domains and the glassy DTE segments. Irrespective of whether PEG was crystalline or not, immersion of these copolymers in water resulted in the formation of hydrated PEG domains that were 10-20 nm apart. Since both water and the polymer chains must be mobile for the phase separation to occur, the PEG domains disappeared when the water froze, and reappeared as the ice began to melt. This transformation was reversible, and showed hysteresis as did the melting of ice and freezing of the water incorporated into the polymer. PEG-water complexes and PEG-water eutectics were observed in WAXS and DSC scans, respectively.

  4. Survey of the year 2008: applications of isothermal titration calorimetry.

    PubMed

    Falconer, Robert J; Penkova, Anita; Jelesarov, Ilian; Collins, Brett M

    2010-01-01

    Isothermal titration calorimetry (ITC) is a fast, accurate and label-free method for measuring the thermodynamics and binding affinities of molecular associations in solution. Because the method will measure any reaction that results in a heat change, it is applicable to many different fields of research from biomolecular science, to drug design and materials engineering, and can be used to measure binding events between essentially any type of biological or chemical ligand. ITC is the only method that can directly measure binding energetics including Gibbs free energy, enthalpy, entropy and heat capacity changes. Not only binding thermodynamics but also catalytic reactions, conformational rearrangements, changes in protonation and molecular dissociations can be readily quantified by performing only a small number of ITC experiments. In this review, we highlight some of the particularly interesting reports from 2008 employing ITC, with a particular focus on protein interactions with other proteins, nucleic acids, lipids and drugs. As is tradition in these reviews we have not attempted a comprehensive analysis of all 500 papers using ITC, but emphasize those reports that particularly captured our interest and that included more thorough discussions we consider exemplify the power of the technique and might serve to inspire other users. PMID:20213668

  5. Comparison of the glass transition temperature and fragility parameter of isomalto-olygomer predicted by molecular dynamics simulations with those measured by differential scanning calorimetry.

    PubMed

    Yoshioka, Sumie; Aso, Yukio

    2005-11-01

    The purpose of this study is to examine whether molecular dynamics (MD) simulations using a commercially available software for personal computers can estimate the glass transition temperature (Tg) of amorphous systems containing pharmaceutically-relevant excipients. MD simulations were carried out with an amorphous matrix model constructed from isomaltoheptaose, and the Tg estimated from the calculated density versus temperature profile was compared with the Tg measured by differential scanning calorimetry (DSC) for freeze-dried isomalto-oligomer having an average molecular weight close to that of isomaltoheptaose. The Tg values determined by DSC were lower by 10 to 20 K than those extrapolated from the Tg values estimated by MD simulation. Fragility parameter was estimated to be 56 and 51 from MD simulation and from DSC measurement, respectively. Thus, the results suggest that MD simulation can provide approximate estimates for the Tg and fragility parameter of amorphous formulations. However, a reduction of the cooling rate, achievable by sufficiently elongating the simulation duration, is necessary for more accurate estimation. PMID:16272728

  6. A detailed thermal study of a Li[Ni0.33Co0.33Mn0.33]O2/LiMn2O4-based lithium ion cell by accelerating rate and differential scanning calorimetry

    NASA Astrophysics Data System (ADS)

    Röder, P.; Baba, N.; Wiemhöfer, H.-D.

    2014-02-01

    Accelerating rate calorimetry (ARC) and differential scanning calorimetry (DSC) were used to study the thermal behaviour of a commercially available lithium-ion cell. Both the complete cell (pouch type, 2 Ah) and its electrode materials, respectively, were investigated. As positive electrode material a blend system consisting of NCM (=Li[Ni0.33Co0.33Mn0.33]O2) and LMO (=LiMn2O4) with a weight ratio of 4:1 was identified. The main exothermic behaviour is dominated by the positive electrode-electrolyte reaction. ARC studies on the positive electrode material in presence of our reference electrolyte show an inhibiting effect of the conducting salt LiPF6 towards the oxidation of the organic based electrolyte by released oxygen. X-ray diffraction measurements were performed to study the thermal decomposition behaviour of the positive active material. Both the blend system and the single components, NCM and LMO, were investigated at different temperatures. A significant phase transformation from the hexagonal layered to a cubic structure as well as various reduction products could be identified. Finally, the thermal behaviour of the NCM/LMO-blend and its single phases, NCM and LMO, at different states of charge (SOC) was investigated. Therefore, detailed investigations based on differential scanning calorimetry (DSC) and cyclic voltammetry (CV) were performed.

  7. Hyperspectral image compression based on the framework of DSC using 3D-wavelet and LDPC

    Microsoft Academic Search

    Jiaji Wu; Kun Jiang; Yong Fang; Licheng Jiao

    2009-01-01

    In this paper, we propose a method based on both 3D-wavelet transform and low-density parity-check codes to realize the compression of hyperspectral images on the framework of DSC (Distributed Source Coding). The new approach which combines DSC and 3D-wavelet transform technique makes it possible to realize low encoding complexity at the encoder and achieve efficient performance of hyperspectral image compression.

  8. Direct self-control (DSC) of inverter-fed induction machine

    Microsoft Academic Search

    M. Depenbrock

    1988-01-01

    The new direct self-control (DSC) is a simple method of signal processing that gives converter-fed three-phase machines an excellent dynamic performance. To control the torque of, say, an induction motor, it is sufficient to process the measured signals of the stator currents and the total flux linkages only. In the basic version of DSC, the power semiconductors of a three-phase

  9. The investigation on states of water in different hydrophilic polymers by DSC and FTIR

    Microsoft Academic Search

    Lan Guan; Hongyan Xu; Dinghai Huang

    2011-01-01

    The interaction between polymers and water in four hydrophilic polymer aqueous solutions were investigated by DSC and FTIR.\\u000a DSC result shows that the different hydrophilic polymer\\/water mixtures have various water calorimetric behaviors in the melting\\u000a temperature range of freezable bound water as well as free water. The melting temperature of freezable water and the amount\\u000a of non-freezable water in the

  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, CO 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. PMID:26004556

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

    PubMed

    Raychaudhuri, Sumana; Espenshade, Peter J

    2015-06-01

    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. PMID:25918164

  12. MicroDSC study of Staphylococcus epidermidis growth

    Microsoft Academic Search

    Dragos C Zaharia; Cezar Iancu; Alexandru T Steriade; Alexandru A Muntean; Octavian Balint; Vlad T Popa; Mircea I Popa; Miron A Bogdan

    2010-01-01

    BACKGROUND: A microcalorimetric study was carried out using a Staphylococcus epidermidis population to determine the reproducibility of bacterial growth and the variability of the results within certain experimental parameters (temperature, bacterial concentration, sample thermal history). Reproducibility tests were performed as series of experiments within the same conditions using either freshly prepared populations or samples kept in cold storage. In both

  13. Differential scanning calorimetry study of reactions of epoxides with polyamines

    Microsoft Academic Search

    F. Severini; R. Gallo; R. Marullo

    1982-01-01

    The reactions of 1,2,3,4-diepoxybutane (DEPB), 1,2,7,8-diepoxyoctane (DEPO), the diglycidyl ether of 1,4-butanediol (DGEBU) and the diglycidyl ether of bisphenol A (DGEBA) with ethylenediamine (EDA), diethylenetriamine (DETA) and tetraethylene-pentamine (TEPA) have been studied with DSC only. The epoxide reactivity decreases according to the sequence: DEPO > DEPB > DGEBU > DGEBA

  14. Interlayer Thermal Conductivity of Rubrene Measured by ac-Calorimetry

    E-print Network

    H. Zhang; J. W. Brill

    2013-07-08

    We have measured the interlayer thermal conductivity of crystals of the organic semiconductor rubrene, using ac-calorimetry. Since ac-calorimetry is most commonly used for measurements of the heat capacity, we include a discussion of its extension for measurements of the transverse thermal conductivity of thin crystals of poor thermal conductors, including the limitations of the technique. For rubrene, we find that the interlayer thermal conductivity, 0.7 mW/cm K, is several times smaller than the (previously measured) in-layer value, but its temperature dependence indicates that the interlayer mean free path is at least a few layers.

  15. Radiation effects on front-end electronics for noble liquid calorimetry

    SciTech Connect

    Citterio, M.; Rescia, S.; Radeka, V.

    1994-12-01

    Front-end electronics for liquid ionization chamber calorimetry at hadron collider experiments may be exposed to substantial levels of ionizing radiation and neutron fluences in a cryogenic environment. Measurements of devices built with rad-hard technologies have shown that devices able to operate in these conditions exist. Si-JFETs and GaAs MESFET devices have been irradiated and tested at a stable cryogenic temperature up to doses of 55 Mrad of ionizing radiation and up to neutron fluences of 4 {times} 10{sup 14} n/cm{sup 2}. Radiation effects on DC characteristics and on noise will be presented.

  16. Determination of thermodynamic and kinetic properties of grain boundaries using high temperature calorimetry

    SciTech Connect

    Terwilliger, C.D.; Chiang, Y.M. (Massachusetts Inst. of Tech., Cambridge, MA (USA)); Eastman, J.A.; Liao, Y. (Argonne National Lab., IL (USA))

    1991-06-01

    This work explores the use of high temperature differential scanning calorimetry as a novel way in which to measure thermodynamic and kinetic properties of grain boundaries in ceramics. A calorimetric study of grain growth has become practical only recently, with the development of processing methods for nanocrystalline materials (10--50 nm grain size) that have enough grain boundary area and thus grain boundary excess properties to be detected by commercial calorimeters. Here we report results from experiments on nanocrystalline silicon and titanium dioxide. 14 refs., 6 figs.

  17. Investigation of an unusual metal-RNA cluster in the P5abc subdomain of the group I intron 

    E-print Network

    Burns, Shannon Naomi

    2006-04-12

    of Mn2+ ions in other RNA structures. The thermodynamic consequence of this metal ion core was probed by thermal denaturation techniques including UV-Vis spectroscopy and differential scanning calorimetry (DSC). DSC experiments were utilized to directly...

  18. Direct measurement of protein binding energetics by isothermal titration calorimetry

    Microsoft Academic Search

    Stephanie Leavitt; Ernesto Freire

    2001-01-01

    Of all the techniques that are currently available to measure binding, isothermal titration calorimetry is the only one capable of measuring not only the magnitude of the binding affinity but also the magnitude of the two thermodynamic terms that define the binding affinity: the enthalpy (?H) and entropy (?S) changes. Recent advances in instrumentation have facilitated the development of experimental

  19. Flexible, Rapid and Automated Analysis of Differential Scanning Calorimetry Data

    E-print Network

    Blaber, Michael

    DSCFIT © Flexible, Rapid and Automated Analysis of Differential Scanning Calorimetry Data USER in Data Analysis I. Loading of Data II. Initial Guess of Thermodynamic Parameters III. The Graphs Dialog MB). As currently implemented, DSCFIT can analyze data sets with 2000, or fewer, data points. Data

  20. 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…

  1. Calorimetry 101 for Cold Fusion; Methods, Problems and Errors

    Microsoft Academic Search

    Edmund Storms

    Application of calorimetry to cold fusion or LENR presents unique problems that have not been previously summarized. This paper discusses various calorimetric methods that have been applied to the subject and evaluates each in light of what has been discovered about their limitations and errors based on experimental studies. Such information is essential to a study of the effect and

  2. High resolution optical calorimetry for synchrotron microbeam radiation therapy

    Microsoft Academic Search

    T. Ackerly; J. C. Crosbie; A. Fouras; G. J. Sheard; S. Higgins; R. A. Lewis

    2011-01-01

    We propose the application of optical calorimetry to measure the peak to valley ratio for synchrotron microbeam radiation therapy (MRT). We use a modified Schlieren approach known as reference image topography (RIT) which enables one to obtain a map of the rate of change of the refractive index in a water bath from which the absorbed dose can be determined

  3. 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. PMID:15212485

  4. Increasing temporal resolution of DSC perfusion MRI using the analytic image concept

    Microsoft Academic Search

    Josiane Yankam Njiwa; David Ratering; Christof Baltes; Markus Rudin

    2010-01-01

    Object  Dynamic susceptibility contrast MRI (DSC-MRI) is increasingly being used to evaluate cerebral microcirculation. In this study,\\u000a the use of the analytic image reconstruction (AIR), with the aim to increase the temporal resolution, is evaluated for DSC-MRI\\u000a in small animals.\\u000a \\u000a \\u000a \\u000a \\u000a Materials and methods  Imaging was performed using a T\\u000a 2*- weighted sequence to acquire male Lewis rats raw data. Results show that

  5. Calorimetry measurements in less than 20 minutes

    NASA Astrophysics Data System (ADS)

    Perry, R. B.; Cremers, T.

    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 5 in. in diameter and 7 in. 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 percent and it is 0.010 watt for sample power less than 1 watt. The 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.

  6. Calorimetry in ZEUS: Lessons for the future

    SciTech Connect

    Derrick, M.

    1988-01-01

    The storage ring facility HERA, under construction at the DESY Laboratory, will collide 30 GeV e/sup /minus// with 820 GeV protons when the machine is first turned on in 1990. Four interaction regions being provided. Subsequently either e/sup /minus// or e beams can be used and a facility for producing longitudinal polarization of the electrons at the interaction points will be provided. Both the center-of-mass energy ( s = 314 GeV) and the momentum transfer (Q/sub max/S /approximately/ 10V GeVS) are substantially higher than in any deep inelastic scattering studies to date. The HERA program will be the natural extension of both the neutrino and the muon scattering experiments done at CERN and Fermilab. With the design luminosity of 1.5 10T cm/sup /minus/2/ sec/sup /minus/1/ experiments with 200 pb/sup /minus/1/ of integrated luminosity will be possible. HERA will be the first electron-quark collider. The energy is substantially higher than LEP, and the events will be cleaner than those resulting from p/bar p/ collisions. It provides the third leg that will support the physics stool of the 1990s. In neutral current events, the z exchange graph is comparable in strength to the photon exchange and the charged current events will provide unique insights into the W coupling. There will be substantial rates of heavy quark production. Two detectors are under construction: H1 uses a large solenoid with a liquid argon calorimeter inside the coil, ZEUS uses a smaller magnet with uranium-scintillator calorimeters outside of the coil. 4 refs., 11 figs.

  7. Applications of differential scanning calorimetry in developing cryopreservation strategies for Parkia speciosa, a tropical tree producing recalcitrant seeds.

    PubMed

    Nadarajan, Jayanthi; Mansor, Marzalina; Krishnapillay, Baskaran; Staines, Harry J; Benson, Erica E; Harding, Keith

    2008-01-01

    Shoot-tips of Parkia speciosa, a recalcitrant seed producing tropical leguminous tree withstood cryopreservation using encapsulation-vitrification in combination with trehalose preculture. Differential scanning calorimetry (DSC) revealed that trehalose moderated the thermal characteristics of the shoot-tips. A 30 min PVS2 treatment had the lowest glass transition temperature (Tg) (-50.2 +/- 1.1 degree C) when applied in combination with 5% (w/v) trehalose. The Tg increased to -40.2 +/- 1.0 degree C as the sugar concentration was decreased to 2.5 percent (w/v). Tg heat capacity for shoot-tips treated with 2.5 percent and 5 percent (w/v) trehalose and exposed to PVS2 for 30 min increased from 0.17 +/ 0.05 to 0.23 +/- 0.01 J per gram, respectively. Enthalpies of the melt-endotherm varied in proportion to trehalose concentration, for the 30 min PVS2 treatment, whereas the melt enthalpy for control shoots was greater than 150 J per gram and decreased to ca. 60 J per gram with 2.5 percent (w/v) trehalose. For 5 percent and 10 percent (w/v) trehalose treatments, enthalpy declined to ca. 24 and 12 J per gram respectively and freezing points were depressed to -75 degree C and -85 degree C with 2.5 percent and 5 percent trehalose (w/v), respectively. DSC elucidated the critical points at which vitrification occurred in germplasm exposed to trehalose and PVS2. A 60 min PVS2 treatment supporting ca. 70 percent survival was found optimal for stable glass formation during cooling and on rewarming. PMID:18516340

  8. 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 increased melting temperature. During the 150 days of physico-chemical aging, an increase in WaMB transition and melting temperature of aliphatic crystallites was was observed. Several types of treatments contrasting with this development were attributed to specific solvent -phenol interactions and will be discussed in this contribution. The results indicate that after introduction of phenol and during the consequent relaxation of the SOM structure, the re-formation of water molecule bridges is significantly reduced and decelerated. WaMB has been suggested as one SOM stabilizing mechanism (Schaumann & Bertmer 2008); the incorporation of phenol destabilizes the physical structure of SOM. It is assumed that phenol can penetrate into the WaMB hotspots, competes with water and/or disrupts WaMB or participate in WaMB formation. Simultaneously, phenol can penetrate and irreversibly change also the aliphatic crystallites, which are traditionally not considered being actively involved in sorption processes. It furthermore could compete with the organic matter for the hydration water. In this contribution, we will discuss these mechanisms. The results clearly demonstrate the potential of DSC to probe labile (physical) structures in soil organic matter and to elucidate interaction of organic chemicals with SOM moieties. References Chilom, G. & Rice, J.A. (2005). Glass transition and crystallite melting in natural organic matter. Organic Geochemistry, 36, 1339-1346. Hu, W.-G.; Mao, J.; Xing, B. & Schmidt-Rohr, K. (2000). Poly(methylene) crystallites in humic substances detected by Nuclear Magnetic Resonance. Environmental Science and Technology, 34, 530-534. Kucerik, J.; Schwarz, J.; Jaeger, A.; Bertmer, M. & Schaumann, G. (submitted 2013). Character of transitions causing physicochemical aging of a sapric histosol. Kunhi Mouvenchery, Y.; Jaeger, A.; Aquino, A.J.A.; Tunega, D.; Diehl, D.; Bertmer, M. & Schaumann, G.E. (2013). Restructuring of a peat in interaction with multivalent cations: Effect of cation type and aging time. PLoS ONE, 8, e65359. Scha

  9. 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 107.7mg/kg, respectively. Phenolic compounds determined for the first time in rose hip oil totalled up to 783.55?g/kg, with a predominant presence of p-coumaric acid methyl ester. Antiradical activity of the oils reached up to 3.00mM/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. PMID:26041218

  10. Fundamental DSC investigations of alpha-keratinous materials as basis for the interpretation of specific effects of chemical, cosmetic treatments on human hair.

    PubMed

    Wortmann, F-J; Sendelbach, G; Popescu, C

    2007-01-01

    Alpha-keratinous materials can be considered as two-phase, filament/matrix composites, in which partly crystalline, alpha-helical intermediate filaments (if) are embedded in an amorphous matrix of IF-associated proteins (IFAP). Differential Scanning Calorimetry (DSC) of keratins in water was found to be especially suited to analyze various aspects of the thermal stability of these main morphological components. Results and considerations are reviewed, which were gained by applying the principles derived from fundamental investigations to the specific effects of oxidation (bleaching) and reduction (perm-waving). Properties and interactions of the main morphological components of human hair are considered that are specifically related to the various aspects of their thermal stability. The overall view of the results shows that the course of the thermal unfolding of the alpha-helix in the IFs is independent of the chemical history of hair. The matrix properties are the primary factor controlling the kinetics of the onset of the denaturation process in the IF/IFAP-composite. PMID:17728931

  11. Polymorphism of 2-nitroaniline studied by calorimetric (DSC), structural (X-ray diffraction) and spectroscopic (FT-IR, Raman, UV Vis) methods

    NASA Astrophysics Data System (ADS)

    Zych, Tomasz; Misiaszek, Tomasz; Szostak, M. Magdalena

    2007-11-01

    The separation and growth methods of three ortho-nitroaniline ( o-NA) polymorphs were found. The irreversible character of the ? ? ? and ? ? ? phase transitions was revealed by differential scanning calorimetry (DSC) measurements and microscopic hot stage observations. The X-ray structure of the ?-form was determined and compared with the ? phase structure solved by Daneshwar et al. [N.N. Daneshwar et al. Acta Crystallogr., Sect. B 34 (1978) 2507]. Intramolecular hydrogen bonding (intra H-bond) interactions are dominant in both structures. The IR and Raman spectral features of the solutions and of three polycrystalline o-NA polymorphs are specific for intramolecular resonance assisted H-bonds (RAHB's). The DFT calculations facilitated the almost complete assignments of bands to normal vibrations and the analysis of the measured spectra. The manifestations of weak inter H-bonds in the ? and ? crystals and in the vibrational spectra of all polymorphs are observed as well; the strongest inter H-bonds occur in the ? polymorph. The differences in lowest electronic transition energies of three ?, ? and ? layers explain their different colours: the yellowish-green of the ? form and the orange ones of the ?- and ?- phases. The least stable ? form is probably an amorphous one with the weakest inter H-bonds. The differences in relative orientations of the -NH 2, -NO 2 groups and phenyl rings in the ?- and ?-phases indicate that the o-NA polymorphism has conformational character.

  12. 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.

  13. Stress Relaxation Under Various Stress and Drainage Conditions Gilberto F. Alexandre, D.Sc.

    E-print Network

    Paris-Sud XI, Université de

    1 Stress Relaxation Under Various Stress and Drainage Conditions Gilberto F. Alexandre, D.Sc. Ian S for stress relaxation tests carried out by Garcia (1996) in the edometric apparatus in a soft organic clay by Terzaghi (1941), Taylor (1942) and others. The differential equation of the stress relaxation test, its

  14. Paula A. Quatromoni, D.Sc., M.S., R.D. Associate Professor with Tenure

    E-print Network

    Guenther, Frank

    Sciences Sargent College of Health and Rehabilitation Sciences Boston University 635 Commonwealth Avenue, Boston, MA 02215 617.353.5797 paulaq@bu.edu EDUCATION 2001 Doctorate of Science (D.Sc.) in Epidemiology Boston University School of Public Health (SPH), Boston, MA 1987 Dietetic Internship, Beth Israel

  15. DSC, TGA and dielectric properties of carboxymethyl cellulose\\/polyvinyl alcohol blends

    Microsoft Academic Search

    S. El-Sayed; K. H. Mahmoud; A. A. Fatah; A. Hassen

    2011-01-01

    Films with different compositions of polyvinyl alcohol (PVA) and carboxymethyl cellulose (CMC) blends have been prepared using the casting method. Differential scanning calorimetery (DSC), thermogravimetric analysis (TGA) and dielectric spectroscopy of all compositions have been investigated. It was found that PVA and CMC are compatible in the studied range of composition. With increasing CMC content, the thermal stability of PVA

  16. DSC --12B --1 EXPERIMENTAL NON-LINEAR DYNAMICS OF A

    E-print Network

    Mavroidis, Constantinos

    DSC --12B --1 EXPERIMENTAL NON-LINEAR DYNAMICS OF A SHAPE MEMORY ALLOY WIRE BUNDLE ACTUATOR Michael of the manipulator is the use of Shape Memory Alloy (SMA) wires as actuators of the manipulator joints. SMA wires, such as Nickel- Titanium (Ni-Ti) wires, have the property of shortening when heated and thus are able to apply

  17. Application of the DSC model for nonlinear analysis of reinforced concrete frames

    Microsoft Academic Search

    Amir Hoshang Akhaveissy; Chandrakant S. Desai

    A nonlinear finite element method with eight-noded isoparametric quadrilateral elements for concrete and two-noded elements for reinforcement was used to predict the behavior of reinforced concrete frame structures. The disturbed state concept (DSC) and the hierarchical single surface (HISS) plasticity model with the associated modified flow rule were used to characterize the constitutive behavior of concrete in both compression and

  18. ESTIMATION OF HRW WHEAT HEAT DAMAGE BY DSC, CAPILLARY ZONE ELECTROPHORESIS, PHOTOACOUSTIC SPECTROSCOPY AND RHEOMETRY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect of heat damage was estimated using Hard Red Winter (HRW) wheat varieties grown in Oklahoma. The testing was done on wheat kernels, flour, and isolated starch. Whole-wheat kernels were analyzed by Photoacoustic Spectroscopy (PAS). Flour was analyzed by DSC, Capillary Electrophoresis (CE...

  19. Comparative study of specific heat capacities of some vegetable oils obtained by DSC and microwave oven

    Microsoft Academic Search

    J. C. O. Santos; M. G. O. Santos; J. P. Dantas; Marta M. Conceição; P. F. Athaide-Filho; A. G. Souza

    2005-01-01

    Summary TG and DSC analyses were carried out in this work to evaluate the changes in the denaturation of human hair keratin submitted to different chemical effects. Hair bleaching and chlorinating treatments caused changes in the denaturation temperatures and denaturation enthalpies of hair keratin. Bleached hair and hair kept in a chlorinated solution presented a lower denaturation enthalpy and a

  20. Photo-DSC cure kinetics of vinyl ester resins. I. Influence of temperature

    Microsoft Academic Search

    Timothy F. Scott; Wayne D. Cook; John S. Forsythe

    2002-01-01

    Isothermal DSC was employed to monitor the photopolymerization kinetics of a commercial vinyl ester resin (VER) photoinitiated by the camphorquinone\\/amine photoinitiator system. The maximum rate of photopolymerization was found to increase tenfold as the isothermal cure temperature was varied from ?30 to 90°C due to faster propagation and greater initiator efficiency counterbalanced by a faster termination rate. After photopolymerization, the

  1. Thermal analytical investigations of ternary Mg-Al-Sr system by DSC

    E-print Network

    Medraj, Mamoun

    and engine parts is limited because of their restricted creep properties. In contrast to steels and many Al. DSC results provided information on the following thermophysical properties: onset temperature properties [1]. The current use of magnesium alloys in more critical components such as transmission

  2. Muscle contribution to elbow joint valgus stability Fang Lin, DSc,a,b,c

    E-print Network

    Makhsous, Mohsen

    Muscle contribution to elbow joint valgus stability Fang Lin, DSc,a,b,c Navjot Kohli, MD,d Sam Repetitive valgus stress of the elbow can result in excessive strain or rupture of the native medial ulnar collateral ligament (MUCL). The flexor-pronator mass (FPM) may be particularly important for elbow valgus

  3. 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.

  4. 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. PMID:20017467

  5. John Marshall Particle Flow Calorimetry 1 J.S. Marshall, M.A. Thomson

    E-print Network

    Glasgow, University of

    John Marshall Particle Flow Calorimetry 1 J.S. Marshall, M.A. Thomson University of Cambridge #12;John Marshall Particle Flow Calorimetry 2 Overview 1. e+e- Physics and LC Jet Energy Requirements 2 at CLIC 8. CLIC Benchmark Physics Analyses 9. Summary #12;John Marshall Particle Flow Calorimetry 3 e

  6. 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

  7. 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.

  8. The Philosophy and Feasibility of Dual Readout Calorimetry

    SciTech Connect

    Hauptman, John [Physics, Iowa State University, Ames IA 50011 (United States)

    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.

  9. Glass transition of heterogeneous polymeric systems studied by calorimetry

    Microsoft Academic Search

    K. Schröter

    2009-01-01

    This personal review focuses on two aspects. First, glass transition dynamics and hence also calorimetry is connected to dynamic\\u000a heterogeneity. This results in an interplay of the corresponding dynamic length scales and length scales from structural heterogeneities\\u000a in polymeric samples. Second, the complexity of the dynamic glass transition itself results in different effects of this interplay\\u000a for different experimental observables.

  10. Extracting longitudinal shower developmentinformation from crystal calorimetry plus tracking

    SciTech Connect

    Brown, D.N.; Ilic, J.; Mohanty, G.B.

    2007-11-16

    We propose a novel approach to derive longitudinal shower development information from a longitudinally unsegmented calorimeter such as the BaBar electromagnetic calorimeter by utilizing tracking information in conjunction with that of calorimetry. We show that using this information as part of an electron identification algorithm results in a significant reduction in the pion misidentification probability for low momentum particles. We also demonstrate how this information provides general charged particle separation at low momentum, particularly between pions and muons.

  11. Anhydrous goat's milk fat: thermal and structural behaviors studied by coupled differential scanning calorimetry and X-ray diffraction. 2. Influence of cooling rate.

    PubMed

    Amara-Dali, Wafa Ben; Lesieur, Pierre; Artzner, Franck; Karray, Nadia; Attia, Hamadi; Ollivon, Michel

    2007-06-13

    Crystallization and melting properties of triacylglycerols (TGs) in anhydrous goat's milk fat (AGMF) are investigated by X-ray diffraction as a function of temperature (XRDT) coupled with high-sensitivity differential scanning calorimetry (DSC), using synchrotron radiation and Microcalix. The polymorphic behavior of AGMF was monitored by varying the cooling rates between 5 and 1 degrees C/min from 45 to -20 degrees C with their subsequent melting at 1 degrees C/min. Quenching of AGMF at -20 degrees C was also examined to determine the metastable polymorphic form of AGMF. At intermediate cooling rates, TGs in AGMF crystallize, from about 18 degrees C in two different lamellar structures with triple chain length 3Lalpha stacking of 72 A and a double chain length 2Lalpha stacking of 48 A, which are correlated to two overlapped exothermic peaks recorded by DSC. A reversible transition sub alpha <--> alpha was observed. Subsequent heating at 1 degrees C/min shows numerous structural rearrangements before final melting. At fast cooling of AGMF (5 degrees C/min), similar unstable crystalline varieties are formed while three endotherms are recorded. Several new unstable lamellar structures are observed after quenching. All of these data are compared to those previously reported at slow cooling (0.1 degrees C/min) showing a relative stability of the structures formed. In spite of general similitude, the thermal and structural behavior of the goat's milk is more complex than that of the cow's milk. PMID:17497873

  12. Polymorphism and cold crystallization in optically nonlinear N-benzyl-2-methyl-4-nitroaniline crystal studied by X-ray diffraction, calorimetry and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Piela, Katarzyna; Turowska-Tyrk, Ilona; Drozd, Marek; Szostak, M. Magdalena

    2011-04-01

    Polymorphism of N-benzyl-2-methyl-4-nitroaniline (BNA), a terahertz emitter and frequency doubler, was detected and the crystal structures of orthorhombic and monoclinic polymorphs have been determined at room temperature. The differential scanning calorimetry (DSC) studies revealed monotropic phase transition of the monoclinic BNA crystal system at 362 K and during re-heating, after the molten BNA cooling, the cold crystallization of the both polymorphs. The variable-temperature Raman spectra in the 700-1700 cm -1 range also evidenced the polymorphic transformation from the monoclinic to the orthorhombic, the latter stable in the wide temperature range, crystal system. The comparison of structures, DSC curves, FT-IR and Raman spectra of two forms enabled to recognize the N sbnd H···O hydrogen bond in the orthorhombic and C sbnd H···O hydrogen bond in the monoclinic one as well as other intermolecular interactions. The role of dynamic disorder, intra- and intermolecular charge transfers in the molecular mechanism of optical nonlinearity has been discussed.

  13. DSC investigation of connective tissues treated by IR-laser radiation

    Microsoft Academic Search

    N. Yu. Ignatieva; V. V. Lunin; S. V. Averkiev; A. F. Maiorova; V. N. Bagratashvili; E. N. Sobol

    2004-01-01

    The structural changes of intact and laser treated connective tissues were investigated by differential scanning calorimetry and thermomechanical analysis. Total collagen denaturation in the fibrous connective tissue was observed. Partial collagen denaturation in the cartilage tissue was proved. By means of enzymatic digestion it was shown that proteoglycans in the cartilage act as thermal stabilizers of the collagen, after their

  14. Subunit Architecture of the Golgi Dsc E3 Ligase Required for Sterol Regulatory Element-binding Protein (SREBP) Cleavage in Fission Yeast*

    PubMed Central

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

    2013-01-01

    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. PMID:23760507

  15. Pressure-modulated differential scanning calorimetry. An approach to the continuous, simultaneous determination of heat capacities and expansion coefficients.

    PubMed

    Boehm, K; Rösgen, J; Hinz, H-J

    2006-02-15

    A new method is described that permits the continuous and synchronous determination of heat capacity and expansibility data. We refer to it as pressure-modulated differential scanning calorimetry (PMDSC), as it involves a standard DSC temperature scan and superimposes on it a pressure modulation of preselected format. The power of the method is demonstrated using salt solutions for which the most accurate heat capacity and expansibility data exist in the literature. As the PMDSC measurements could reproduce the parameters with high accuracy and precision, we applied the method also to an aqueous suspension of multilamellar DSPC vesicles for which no expansibility data had been reported previously for the transition region. Excellent agreement was obtained between data from PMDSC and values from independent direct differential scanning densimetry measurements. The basic theoretical background of the method when using sawtooth-like pressure ramps is given under Supporting Information, and a complete statistical thermodynamic derivation of the general equations is presented in the accompanying paper. PMID:16478087

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

    NASA Astrophysics Data System (ADS)

    Migda?-Mikuli, Anna; Szostak, El?bieta

    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.

  17. 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 (?H) were observed as an effect of cross-linkage. An increase in acid adipic concentration produced an increase in Tonset and a decrease in ?H. pH and temperature. The cross-linked of banana starch produced granules more resistant during the pasting procedure.

  18. Bridging Calorimetry and Simulation through Precise Calculations of Cucurbituril-Guest Binding Enthalpies.

    PubMed

    Fenley, Andrew T; Henriksen, Niel M; Muddana, Hari S; Gilson, Michael K

    2014-09-01

    We used microsecond time scale molecular dynamics simulations to compute, at high precision, binding enthalpies for cucurbit[7]uril (CB7) with eight guests in aqueous solution. The results correlate well with experimental data from previously published isothermal titration calorimetry studies, and decomposition of the computed binding enthalpies by interaction type provides plausible mechanistic insights. Thus, dispersion interactions appear to play a key role in stabilizing these complexes, due at least in part to the fact that their packing density is greater than that of water. On the other hand, strongly favorable Coulombic interactions between the host and guests are compensated by unfavorable solvent contributions, leaving relatively modest electrostatic contributions to the binding enthalpies. The better steric fit of the aliphatic guests into the circular host appears to explain why their binding enthalpies tend to be more favorable than those of the more planar aromatic guests. The present calculations also bear on the validity of the simulation force field. Somewhat unexpectedly, the TIP3P water yields better agreement with experiment than the TIP4P-Ew water model, although the latter is known to replicate the properties of pure water more accurately. More broadly, the present results demonstrate the potential for computational calorimetry to provide atomistic explanations for thermodynamic observations. PMID:25221445

  19. A new approach for non-contact calorimetry: system identification using pseudo-white noise perturbation

    NASA Astrophysics Data System (ADS)

    Schetelat, Pascal; Etay, Jacqueline

    2011-07-01

    This paper presents a new technique for non-contact calorimetry measurement of specific heat capacity and thermal conductivity. Based on pseudo-white noise modulation and system identification, commonly used in electronics and communication engineering, this procedure can be used to measure the transfer function of the sample temperature variation due to heating power variation. The heat capacity and internal heat transfer coefficient are then determined using the equivalence between the identified transfer functions of the temperatures measured at two locations and the analytical model proposed by Fecht and Johnson (Rev Sci Instrum 62:1299-1303, 1991) and Wunderlich and Fecht (Measur Sci Technol 16:402-416, 2005). This inverse problem is solved numerically using a Gauss-Seidel algorithm. A numerical simulation of a non-contact modulated calorimetry experiment is used to demonstrate the relevance of this new technique for indirect measurement of the heat capacity and heat transfer coefficients of solid samples presenting large Biot numbers ( Bi > 0.4).

  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 Central

    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.

    2012-01-01

    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. PMID:22086920

  1. Synthesis, characterization and TG–DSC study of cadmium halides adducts with caffeine

    Microsoft Academic Search

    Robson F. de Farias; Ademir O. da Silva; Umberto G. da Silva

    2003-01-01

    The synthesis, characterization and TG–DSC study of the compounds CdX2·ncaff, for which X: Cl, Br and I; n=1 and 2 and caff: caffeine is reported. It is verified that caffeine is coordinated through more than one coordination site, despite the fact that the nitrogen of the imidazole ring is the main coordination site. The following thermal stability trend is observed:

  2. Flammability kinetics from TGA\\/DSC\\/GCMS, microcalorimetry and computational quantum chemistry

    Microsoft Academic Search

    Phillip R. Westmoreland; Taline Inguilizian; Karin Rotem

    2001-01-01

    Flammability hazards and mechanisms have been analyzed for mg-scale samples of polymers by integrating the use of a new TGA\\/DSC\\/GCMS technique, the PCFC microcalorimeter developed by Lyon, and computational quantum chemistry. The first apparatus is based on a Rheometrics STA 1500. Head space immediately above the polymer is sampled through a microprobe and heated transport line into a multiport valve

  3. Dynamic mechanical analysis (DMA) of new and historical parchments and leathers: Correlations with DSC and XRD

    Microsoft Academic Search

    A. Cucos; P. Budrugeac; L. Miu; S. Mitrea; G. Sbarcea

    2011-01-01

    A sort of pure collagen, 22 sorts of new parchments, 35 sorts of old (14th–19th centuries) parchments, 19 sorts of new vegetable tanned leathers and 31 sorts of old (15th–19th centuries) leathers were investigated by DMA technique in tensile mode from room temperature to 260°C. The obtained results were correlated with those determined by DSC measurements performed in N2 flow

  4. A fully automated method for quantitative cerebral hemodynamic analysis using DSC–MRI

    PubMed Central

    Bjørnerud, Atle; Emblem, Kyrre E

    2010-01-01

    Dynamic susceptibility contrast (DSC)-based perfusion analysis from MR images has become an established method for analysis of cerebral blood volume (CBV) in glioma patients. To date, little emphasis has, however, been placed on quantitative perfusion analysis of these patients, mainly due to the associated increased technical complexity and lack of sufficient stability in a clinical setting. The aim of our study was to develop a fully automated analysis framework for quantitative DSC-based perfusion analysis. The method presented here generates quantitative hemodynamic maps without user interaction, combined with automatic segmentation of normal-appearing cerebral tissue. Validation of 101 patients with confirmed glioma after surgery gave mean values for CBF, CBV, and MTT, extracted automatically from normal-appearing whole-brain white and gray matter, in good agreement with literature values. The measured age- and gender-related variations in the same parameters were also in agreement with those in the literature. Several established analysis methods were compared and the resulting perfusion metrics depended significantly on method and parameter choice. In conclusion, we present an accurate, fast, and automatic quantitative perfusion analysis method where all analysis steps are based on raw DSC data only. PMID:20087370

  5. 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

  6. 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.

  7. Thermal characteristics of second harmonic generation by phase matched calorimetry.

    PubMed

    Lim, Hwan Hong; Kurimura, Sunao; Noguchi, Keisuke; Shoji, Ichiro

    2014-07-28

    We analyze a solution of the heat equation for second harmonic generation (SHG) with a focused Gaussian beam and simulate the temperature rise in SHG materials as a function of the second harmonic power and the focusing conditions. We also propose a quantitative value of the heat removal performance of SHG devices, referred to as the effective heat capacity C? in phase matched calorimetry. We demonstrate the inverse relation between C? and the focusing parameter ?, and propose the universal quantity of the product of C? and ? for characterizing the thermal property of SHG devices. Finally, we discuss the strategy to manage thermal dephasing in SHG using the results from simulations. PMID:25089446

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

    PubMed

    Fernández, José M; Plaza, César; Polo, Alfredo; Plante, Alain F

    2012-01-01

    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) techniques. Total amounts of CO(2) respired indicated that the organic matter in the TS was the least stable, while that in the CS was the most stable. This was confirmed by changes detected with the spectroscopic methods in the composition of the organic wastes due to C mineralization. Differences were especially pronounced for TS, which showed a remarkable loss of aliphatic and proteinaceous compounds during the incubation process. TG, and especially DSC analysis, clearly reflected these differences between the three organic wastes before and after the incubation. Furthermore, the calculated energy density, which represents the energy available per unit of organic matter, showed a strong correlation with cumulative respiration. Results obtained support the hypothesis of a potential link between the thermal and biological stability of the studied organic materials, and consequently the ability of thermal analysis to characterize the maturity of municipal organic wastes and composts. PMID:21944875

  9. Lipid migration in two-phase chocolate systems investigated by NMR and DSC

    Microsoft Academic Search

    Peggy Walter; Paul Cornillon

    2002-01-01

    The migration of lipids in two-phase chocolate systems (i.e. lauric acid+chocolate and peanut butter+chocolate) was analyzed by magnetic resonance and differential scanning calorimetry. Kinetics of fat migration was evaluated and the diffusion coefficient of lauric acid in chocolate was found to be dependent on migration time. This may be due to the capillary nature of fat migration in chocolate. Fat

  10. 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.

  11. 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.

  12. 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.

  13. Application of Large Scale GEM for Digital Hadron Calorimetry

    NASA Astrophysics Data System (ADS)

    Yu, J.; Baldelomar, E.; Park, K.; Park, S.; Sosebee, M.; Tran, N.; White, A. P.

    The detectors proposed for future e+e- colliders (ILC and CLIC) demand a high level of precision in the measurement of jet energies. Various technologies have been proposed for the active layers of the digital hadron calorimetry to be used in conjunction with the Particle Flow Algorithm (PFA) approach. The High Energy Physics group of the University of Texas at Arlington has been developing Gas Electron Multiplier (GEM) detectors for use as the calorimeter active gap detector. To understand this application of GEMs, two kinds of prototype GEM detectors have been tested. One has 30x30 cm2 active area double GEM structure with a 3 mm drift gap, a 1 mm transfer gap and a 1 mm induction gap. The other one has two 2x2 cm2 GEM foils in the amplifier stage with a 5 mm drift gap, a 2 mm transfer gap and a 1 mm induction gap. We will summarize the results of tests of these prototypes, using cosmic rays and sources, in terms of their applicability to a digital hadron calorimeter system. We will discuss plans for the construction of 1m2 layers of GEM digital hadron calorimetry to be used as part of a 1m3 stack to be used in a major test beam study of hadronic showers.

  14. Calorimetry exchange program quarterly data report, third quarter 1992

    SciTech Connect

    Barnett, T.M.

    1992-12-31

    The goals of the Calorimetry Sample Exchange Program are: 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 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 been collected to the same precision or for the same time periods. This report provides data for the third quarter of 1992.

  15. 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''.

  16. A DSC study of deterioration caused by environmental chemical pollutants to parchment, a collagen-based material

    Microsoft Academic Search

    Petru Budrugeac; Elena Badea; Giuseppe Della Gatta; Lucretia Miu; Alina Com?nescu

    2010-01-01

    A DSC study of new parchments exposed at 25°C for 1–16 weeks to controlled atmospheres containing 50ppm of gaseous chemical pollutants (NO2, SO2, NO2+SO2) and 50% relative humidity (RH) was performed. Samples were exposed to chemical pollutants alone, as well as after previous heating at 100°C for 2–16 days and\\/or irradiating with visible light (1.7×105lx) for 4–16h. DSC measurements were

  17. DSC and DC conductivity of ZnO.LiF.B2O3 glasses

    NASA Astrophysics Data System (ADS)

    Arora, Susheel; Dahiya, Sajjan; Kundu, Virender; Goyal, D. R.; Maan, A. S.

    2013-06-01

    Melt-quench technique has been used to prepare fluoroborate glasses with ZnO content and having compositions x ZnO. (40-x) LiF. 60 B2O3 (x = 0, 5, 10, 15 and 20). DSC characterization is carried out to observe glass transition temperature. Two glass transition temperatures are observed for each of the reported samples. Both transition temperatures are found to increase with increase in ZnO content. DC conductivity is examined with respect to temperature variations. Results show that the conductivity is ionic in nature and varies with the variations in ZnO concentration.

  18. 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) - 320?KWW) and compared with acetaminophen and methocarbamol. The sample studied here is found to be kinetically strong in comparison.

  19. TG-DSC method applied to drying characteristics and heat requirement of cotton stalk during drying

    NASA Astrophysics Data System (ADS)

    Chen, Dengyu; Li, Ming; Zhu, Xifeng

    2012-12-01

    Drying characteristics of cotton stalk were investigated at four temperatures (60, 80, 100 and 120 °C) using a simultaneous thermal analyzer (TG-DSC). Heat requirements of cotton stalk during drying were calculated ranging from 189 to 406 kJ/kg. Consequently, Midilli-Kucuk model showed the best fit to experimental drying data. The values of effective diffusivity ranged from 4.38 × 10-9 to 8.15 × 10-9 m2/s, and the activation energy was calculated to be 11.6 kJ/mol.

  20. Mobility and age of black carbon in two temperate grassland soils revealed by differential scanning calorimetry and radiocarbon dating

    NASA Astrophysics Data System (ADS)

    Leifeld, Jens; Feng, Xiaojuan; Eglinton, Timothy; Wacker, Lukas

    2015-04-01

    Black carbon (BC) is a natural component of soil organic matter (SOM) and abundant in many ecosystems. Its stability, due to its relative resistance to microbial decomposition, means it plays an important role in soil C sequestration. A recent review suggests that BC may be mobile in soil; hence, its contribution to a stable SOM pool may change over time due to its lateral or vertical reallocation (Rumpel et al. 2014). However, direct evidence of the mobility of BC, particularly with reference to its vertical mobility, is scarce. We studied the amount of BC in two temperate grassland fields (eutric clayey Camibsol,) that were established in 2001 on former cropland. Volumetric soil samples (0-50 cm, 5 cm increments) were taken at 10 spots in each field in 2001, 2006 and 2011. One of the fields was ploughed in 2007 and the sward was re-sown. BC content was measured by differential scanning calorimetry for a total number of c. 500 samples. The mean BC/OC ratio was 0.10 (±0.05) and reached 0.25 in some samples. Radiocarbon measurements from 24 bulk soil samples revealed relatively small 14C contents in 2001 (92±2.7 pMC) which increased over time (2006: 99.0±1.1 pMC; 2011: 99.1±1.1 pMC). Thermal fractionation of BC by DSC revealed calibrated BC ages of 400 to 1000 years (pMC 87-94), suggesting that BC originates from medieval and post-medieval fire clearings. The change in soil signature may have been caused by a preferential transport of old BC down the soil profile, leading to a selective enrichment of younger soil C over time. In line with this interpretation the DSC measurements suggest that in both fields, BC concentrations significantly decreased for most layers between 2001 and 2006. However, between 2006 and 2011, no further vertical reallocation was observed in the continuous grassland, whereas BC contents of the field ploughed in 2007 significantly increased in the top layers. Together, these data suggest that ploughing in 2001 triggered subsequent downwards movement of BC, a process which ceased after a few years. Repeated ploughing lifted up some of the BC from deeper layers and this material will probably be transported downwards in the future. Rumpel, C. et al. (2014) Movement of biochar in the environment. In: Lehmann, J. (Ed.): Biochar for the Environment, accepted.

  1. 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 of amorphous solid water in bulk and confining geometry (ultrathin films and nano-aggregates). Bulk-like water samples were prepared by vapor-deposition on the surface of a tungsten filament near 140 K where vapor-deposition results in low enthalpy glassy water films. The vapor deposition approach was also used to grow nano-aggregates (2- 20 nm thick) and multiple ultrathin (approximately 50 nm thick) water films alternated with benzene and methanoic films of similar dimensions. When heated from cryogenic temperatures, the ultrathin water films underwent a well manifested glass softening transition at temperatures 20 degrees below the onset of crystallization. The thermograms of nano-aggregates of ASW films show two endotherms at 40 and 10 K below the onset temperatures of crystallization. However, no such transition was observed in bulk-like water samples prior to their crystallization. These results indicate that water in confined geometry demonstrates glass softening dynamics which are dramatically distinct from those of the bulk phase. We attribute these differences to water's interfacial glass transition which occurs at temperatures tens of degrees lower than that in the bulk. Implications of these finding for past studies of glass softening dynamics in various glassy water samples are discussed in chapter 5 and 6.

  2. Hydroxylamine nitrate self-catalytic kinetics study with adiabatic calorimetry.

    PubMed

    Liu, Lijun; Wei, Chunyang; Guo, Yuyan; Rogers, William J; Sam Mannan, M

    2009-03-15

    Hydroxylamine nitrate (HAN) is an important member of the hydroxylamine compound family with applications that include equipment decontamination in the nuclear industry and aqueous or solid propellants. Due to its instability and autocatalytic behavior, HAN has been involved in several incidents at the Hanford and Savannah River Site (SRS) [Technical Report on Hydroxylamine Nitrate, US Department of Energy, 1998]. Much research has been conducted on HAN in different areas, such as combustion mechanism, decomposition mechanism, and runaway behavior. However, the autocatalytic decomposition behavior of HAN at runaway stage has not been fully addressed due to its highly exothermic and rapid decomposition behavior. This work is focused on extracting HAN autocatalytic kinetics and analyzing HAN critical behavior from adiabatic calorimetry measurements. A lumped autocatalytic kinetic model for HAN and associated model parameters are determined. Also the storage and handling critical conditions of diluted HAN solution without metal presence are quantified. PMID:18639378

  3. 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.

  4. Hadronic Shower Development in Tile Iron-Scintillator Calorimetry

    E-print Network

    Yuri A. Kulchitsky

    1999-10-07

    The lateral and longitudinal profiles of hadronic showers detected by a prototype of the ATLAS Iron-Scintillator Tile Hadron Calorimeter have been investigated. This calorimeter uses a unique longitudinal configuration of scintillator tiles. Using a fine-grained pion beam scan at 100 GeV, a detailed picture of transverse shower behavior is obtained. The underlying radial energy densities for four depth segments and for the entire calorimeter have been reconstructed. A three-dimensional hadronic shower parametrization has been developed. The results presented here are useful for understanding the performance of iron-scintillator calorimeters, for developing fast simulations of hadronic showers, for many calorimetry problems requiring the integration of a shower energy deposition in a volume and for future calorimeter design.

  5. Hadronic Shower Development in Iron-Scintillator Tile Calorimetry

    E-print Network

    Tilecal Atlas Collaboration

    1999-04-29

    The lateral and longitudinal profiles of hadronic showers detected by a prototype of the ATLAS Iron-Scintillator Tile Hadron Calorimeter have been investigated. This calorimeter uses a unique longitudinal configuration of scintillator tiles. Using a fine-grained pion beam scan at 100 GeV, a detailed picture of transverse shower behavior is obtained. The underlying radial energy densities for four depth segments and for the entire calorimeter have been reconstructed. A three-dimensional hadronic shower parametrization has been developed. The results presented here are useful for understanding the performance of iron-scintillator calorimeters, for developing fast simulations of hadronic showers, for many calorimetry problems requiring the integration of a shower energy deposition in a volume and for future calorimeter design.

  6. Calorimetry with Nonequilibrium Phonon Sensors for Dark Matter Direct Detection

    SciTech Connect

    Dragowsky, Michael [Physics Department, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH (United States)

    2006-10-27

    Low-temperature calorimetric particle detectors are applied to the problem of dark matter detection. These semiconductor crystal-based devices operate at sub-Kelvin temperatures. Nuclear-recoil interactions can be distinguished from electron-recoils by comparing the thermal energy yield with that in another channel, such as ionization or scintillation, essential in the search for dark matter and potentially quite useful in measuring neutrino-nucleus scattering cross-sections. The Cryogenic Dark Matter Search collaboration has demonstrated in phase two (CDMS II) that athermal phonon sensors instrumented with direct-current SQUID arrays achieve additional background rejection encoded in the pulse shape, particularly associated with leading edge features. This talk will present the general ideas of applying calorimetry to dark matter detection. It will also present CDMS II detector design and performance, and discuss future plans for dark matter direct detection with this approach.

  7. 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. PMID:24986754

  8. Response evolution of the CMS ECAL and R&D studies for electromagnetic calorimetry at the High-Luminosity LHC

    E-print Network

    Nessi-Tedaldi, Francesca

    2012-01-01

    While the CMS experiment is currently harvesting LHC collision data at CERN, the performance of its electromagnetic calorimeter (ECAL) is being constantly monitored, and work has started to assess the need for changes to the detector to ensure an adequate performance for High-Luminosity LHC (HL-LHC) running, which is planned for 2022 and beyond. In this paper, results from CMS running, beam tests and laboratory measurements are combined to anticipate the detector performance evolution at the HL-LHC. Further, various R&D studies are illustrated, that will provide a useful choice for electromagnetic calorimetry at the HL-LHC.

  9. Response evolution of the CMS ECAL and R&D studies for electromagnetic calorimetry at the High-Luminosity LHC

    E-print Network

    Francesca Nessi Tedaldi; for the CMS Collaboration

    2012-11-16

    While the CMS experiment is currently harvesting LHC collision data at CERN, the performance of its electromagnetic calorimeter (ECAL) is being constantly monitored, and work has started to assess the need for changes to the detector to ensure an adequate performance for High-Luminosity LHC (HL-LHC) running, which is planned for 2022 and beyond. In this paper, results from CMS running, beam tests and laboratory measurements are combined to anticipate the detector performance evolution at the HL-LHC. Further, various R&D studies are illustrated, that will provide a useful choice for electromagnetic calorimetry at the HL-LHC.

  10. Correction for Arterial-Tissue Delay and Dispersion in Absolute Quantitative Cerebral Perfusion DSC MR Imaging

    PubMed Central

    Mouannes-Srour, Jessy J.; Shin, Wanyong; Ansari, Sameer A.; Hurley, Michael C.; Vakil, Parmede; Bendok, Bernard R.; Lee, John L.; Derdeyn, Colin P.; Carroll, Timothy J.

    2011-01-01

    The singular value decomposition deconvolution of cerebral tissue concentration-time (C-T) curves with the arterial input function (AIF) is commonly used in dynamic susceptibility contrast (DSC) cerebral perfusion MR imaging. However, it is sensitive to the time discrepancy between the arrival of the bolus in the tissue C-T curve and the AIF signal. This normally causes inaccuracy in the quantitative perfusion maps due to delay and dispersion effects. A comprehensive correction algorithm has been achieved through slice-dependent time-shifting of the AIF, and a delay-dependent dispersion correction model. The correction algorithm was tested in 11 healthy subjects and 3 ischemic stroke patients scanned with a quantitative perfusion pulse sequence at 1.5T. A validation study was performed on 5 patients with confirmed cerebrovascular occlusive disease scanned with MRI and positron emission tomography (PET) at 3.0T. A significant effect (p<0.05) was reported on the quantitative cerebral blood flow and mean transit time measurements (up to 50%). There was no statistically significant effect on the quantitative cerebral blood volume values. The in vivo results were in agreement with the simulation results, as well as previous literature. This minimizes the bias in patient diagnosis due to the existing errors and artifacts in DSC imaging. PMID:22162092

  11. The energy density of jellyfish: Estimates from bomb-calorimetry and proximate-composition

    E-print Network

    Hays, Graeme

    The energy density of jellyfish: Estimates from bomb-calorimetry and proximate-composition Thomas K scyphozoan jellyfish (Cyanea capillata, Rhizostoma octopus and Chrysaora hysoscella). First, bomb). These proximate data were subsequently converted to energy densities. The two techniques (bomb- calorimetry

  12. The role of adsorption calorimetry in the study of surface phenomena

    Microsoft Academic Search

    G. Wedler

    1978-01-01

    After a short survey of the development of adsorption calorimetry, the current position of this method is demonstrated in the light of some more recent results. A critical analysis is made of the areas in which adsorption calorimetry could be successfully applied in the future, either alone or, preferably, in combination with other techniques.

  13. 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.

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

    PubMed

    Cibulková, Zuzana; ?ertík, 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. PMID:24360453

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

    NASA Astrophysics Data System (ADS)

    Kök, M.; Aydo?du, 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.

  16. High resolution optical calorimetry for synchrotron microbeam radiation therapy

    NASA Astrophysics Data System (ADS)

    Ackerly, T.; Crosbie, J. C.; Fouras, A.; Sheard, G. J.; Higgins, S.; Lewis, R. A.

    2011-03-01

    We propose the application of optical calorimetry to measure the peak to valley ratio for synchrotron microbeam radiation therapy (MRT). We use a modified Schlieren approach known as reference image topography (RIT) which enables one to obtain a map of the rate of change of the refractive index in a water bath from which the absorbed dose can be determined with sufficient spatial accuracy to determine the peak to valley ratio. We modelled the calorimetric properties of X-rays using a heated wire in a water bath. Our RIT system comprised a light source, a textured reference object and a camera and lens combination. We measured temperature contours and showed a plume rising from the heated wire. The total temperature change in water was 12 degrees C, 500 times greater than the calculated change from a 1 ms exposure on a synchrotron. At 1.0 ms, thermal diffusion will be the major cause of uncertainty in determining the peak to valley ratio, and we calculate thermal diffusion will reduce the measured peak to valley ratio to 76% of its initial value, but the individual microbeams will still resolve. We demonstrate proof of concept for measuring X-ray dose using a modified RIT method.

  17. Combination of isothermal titration calorimetry and time-resolved luminescence for high affinity antibody-ligand interaction thermodynamics and kinetics

    PubMed Central

    Aweda, Tolulope A.; Meares, Claude F.

    2011-01-01

    For experiments using synthetic ligands as probes for biological experiments, it is useful to determine the specificity and affinity of the ligands for their receptors. As ligands with higher affinities are developed (KA >108 M?1; KD <10?8 M), a new challenge arises: to measure these values accurately. Isothermal titration calorimetry measures heat produced or consumed during ligand binding, and also provides the equilibrium binding constant. However, as normally practiced, its range is limited. Displacement titration, where a competing weaker ligand is used to lower the apparent affinity of the stronger ligand, can be used to determine the binding affinity as well as the complete thermodynamic data for ligand-antibody complexes with very high affinity. These equilibrium data have been combined with kinetic measurements to yield the rate constants as well. We describe this methodology, using as an example antibody 2D12.5, which captures yttrium S-2-(4-aminobenzyl)-1, 4, 7, 10-tetraazacyclododecanetetraacetate. PMID:21964396

  18. 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.

  19. An isoperibol calorimeter for the investigation of biochemical kinetics and isothermal titration calorimetry

    E-print Network

    Amadi, Ovid Charles

    2007-01-01

    Isothermal titration calorimetry is a technique used to measure the enthalpy change associated with a molecular binding interaction. From these data, the binding constant for the reaction can be determined. In the scope ...

  20. Isothermal Crystallization Kinetics of In Situ Photo and Thermo Aged Poly(Ethylene Oxide) Using PhotoDSC

    E-print Network

    Paris-Sud XI, Université de

    in a single device irradiation, heating and DSC analysis, was considered for measuring the rate of isothermal of these materials. A well-documented paper, comparing Avrami, Tobin, Malkin and Urbanovici- Segal macrokinetic for environmental and medical applications [8, 9, 10]. The mechanisms of thermo and photooxidation of PEO have

  1. Comparison of first pass bolus AIFs extracted from sequential (^18)F-FDG PET and DSC-MRI of mice

    E-print Network

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

    2013-08-29

    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...

  2. Non-freezing water content of mono- and divalent cation salts of polyelectrolyte-water systems studied by DSC

    Microsoft Academic Search

    Tatsuko Hatakeyama; Hyoe Hatakeyama; Kunio Nakamura

    1995-01-01

    The number of bound water molecules restricted by mono-, di-, and trivalent cations in polyelectrolytes, such as polystyrene sulphonate, carboxymethylcellulose and alginic acid, was calculated using DSC. The number of bound water molecules decreases with increasing ionic radius in the series of mono- and divalent cations when polyelectrolytes form the liquid crystalline state. However, when polyelectrolytes form rigid junction zones

  3. Effective dose: a flawed concept that could and should be D J BRENNER, PhD, DSc

    E-print Network

    Brenner, David Jonathan

    COMMENTARY Effective dose: a flawed concept that could and should be replaced D J BRENNER, PhD, DSc. The effective dose is designed to provide a single number proportional to the radiobiological ``detriment'' from associated with different spatial dose distributions produced by different imaging techniques. The effective

  4. Characterization of soluble amaranth and soybean proteins based on fluorescence, hydrophobicity, electrophoresis, amino Acid analysis, circular dichroism, and differential scanning calorimetry measurements.

    PubMed

    Gorinstein, S; Delgado-Licon, E; Pawelzik, E; Permady, H H; Weisz, M; Trakhtenberg, S

    2001-11-01

    Intrinsic fluorescence (IF), surface hydrophobicity (S(o)), electrophoresis, amino acid analysis, circular dichroism (CD), and differential scanning calorimetry (DSC) were used to study folded and unfolded soluble proteins from Amaranthus hypochondriacus (A. h.) and soybean (S). Globulin (Glo) and albumin subfractions (Alb-1 and Alb-2) were extracted from A. h. and S and denatured with urea. Electrophoretic and functional properties indicated a significant correlation between soluble protein fractions from soybean and amaranth. The protein fractions shared some common electrophoretic bands as well as a similar amino acid composition. The larger percent of denaturation in protein fractions, which is associated with enthalpy and the number of ruptured hydrogen bonds, corresponds to disappearance of alpha-helix. The obtained results provided evidence of differences in their secondary and tertiary structures. The most stable was Glo followed by the Alb-2 fraction. Predicted functional changes in model protein systems such as pseudocereals and legumes in response to processing conditions may be encountered in pharmaceutical and food industries. These plants can be a substitute for some cereals. PMID:11714365

  5. Isothermal calorimetry investigation of Li{sub 1+x}Mn{sub 2-y}Al{sub z}O{sub 4} spinel.

    SciTech Connect

    Lu, W.; Belharouak, I.; Park, S. H.; Sun, Y. K; Amine, K.; Chemical Engineering; Hanyang Univ.

    2007-05-25

    The heat generation of LiMn{sub 2}O{sub 4}, Li{sub 1.156}Mn{sub 1.844}O{sub 4}, and Li{sub 1.06}Mn{sub 1.89}Al{sub 0.05}O{sub 4} spinel cathode materials in a half-cell system was investigated by isothermal micro-calorimetry (IMC). The heat variations of the Li/LiMn{sub 2}O{sub 4} cell during charging were attributed to the LiMn{sub 2}O{sub 4} phase transition and order/disorder changes. This heat variation was largely suppressed when the stoichiometric spinel was doped with excess lithium or lithium and aluminum. The calculated entropy change (dE/dT) from the IMC confirmed that the order/disorder change of LiMn{sub 2}O{sub 4}, which occurs in the middle of the charge, was largely suppressed with lithium or lithium and aluminum doping. The dE/dT values obtained did not agree between the charge and the discharge at room temperature (25 C), which was attributed to cell self-discharge. This discrepancy was not observed at low temperature (10 C). Differential scanning calorimeter (DSC) results showed that the fully charged spinel with lithium doping has better thermal stability.

  6. 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. This is exhibited by the exotherm. Heating the so-cooled samples, in general, increases their melting point in almost all samples. Thus melting event is shifted towards higher temperature, except for one sample in which pre-twist level is appreciably high. Thus, DSC is a very useful technique to select and optimize the pre-twist level and may provide quite a significant insight into the thermal stability of the mechanical crimp textured yarn.

  7. 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

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

    SciTech Connect

    Matsuda, Yu; Ike, Yuji [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8571 (Japan); Matsui, Chihiro [College of Engineering Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8573 (Japan); Kodama, Masao [Department of Applied Chemistry, Sojo University, Kumamoto, 860-0082 (Japan); Kojima, Seiji [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8571 (Japan); College of Engineering Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8573 (Japan)

    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.

  9. [Raman and DSC spectroscopic studies on the interaction between ginsenosides and DMPC bilayer membranes].

    PubMed

    Hui, Ge; Zhao, Yu; Zhang, Jing-Zhou; Liu, Wei; Li, Hong-Dong; Zhao, Bing

    2014-02-01

    Study the effect of drugs and biological membranes is of prime importance on understanding drugs' curative effects and improving their biological properties. In this article, Raman spectrum has been combined with differential thermal scanning technology to discuss the relationship between five categories of ginsenoside molecules and DMPC bilayer films. Raman results indicated that the saponin molecules have not altered the polarity conformation of O-C-C-N+ backbone in DMPC bilayers, and the polarity head still paralleled to the membrane surface. The order of the internal molecular chain and the lateral chain-chain packing have been decreased as the panaxadiol saponins Rb1 and Rh2 increased, and to the opposite, the panaxatriol saponins Re, Rf and Rg1 have showed weak effects on DMPC bilayers. The DSC showed further results that the strong effects of ginsenoside Rb1 and Rh2 on DMPC, which both have obviously reduced the DMPC molecular phase transition temperature, thus increasing the fluidity of bilayers. In addition, panaxatriol saponin Rf has displayed stronger disturbance effect on DMPC than Re and Rg1. PMID:24822411

  10. 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?

  11. Comparative studies on the non-isothermal DSC curing kinetics of an unsaturated polyester resin using free radicals and empirical models

    Microsoft Academic Search

    J. L. Martín; A. Cadenato; J. M. Salla

    1997-01-01

    In this paper, we study the kinetics of the curing of an unsaturated polyester resin initiated with MEKP by means of DSC. DSC runs were performed at different heating rates. The experimental curves were fitted using two kinetic models: one involving the concept of free-radical polymerization, and the other an empirical model that does not take into account the different

  12. Structural refinement and DSC characterization of PEEK fiber. [Poly(aryletheretherketone)

    SciTech Connect

    Fratini, A.V.; Cross, E.M.; Whitaker, R.B.

    1986-06-03

    The crystalline structure of oriented fibers of poly(aryletheretherketone) (PEEK) has been analyzed by x-ray diffraction and refined by the Linked-Atom Least-Squares procedure. The conformation of chains, consisting of a six-aryl ring unit, is approximated by the refinement of a two-aryl ring unit within the orthorhombic unit subcell with dimensions: a = 7.83 +- 0.02 A, b = 5.94 +- 0.01 A, and c = 9.86 +- 0.04 A. Certain constraints imposed by Pbcn space group symmetry are relaxed during refinement. The results of the two-ring refinement indicate that a single torsion angle can be used to describe the conformation of the six-ring unit. The torsion angle corresponds to the average tilt of the phenylene rings out of the (100) face, and the best fit is obtained with an angle of 37/sup 0/. The simulated powder diffraction pattern based on the atomic coordinates of the six-ring unit matches very closely previously reported patterns for a variety of PEEK specimens. The analysis supports, and extends to oriented fibers, the previously reported finding that space group Pbcn is a valid representation for the structure of PEEK. Differential scanning calorimetry established that the PEEK samples were typical PEEK material.

  13. 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 dioxide deposited on a gold surface dramatically enhances NF-RHT between the coated surface and a second silica surface. Specifically, we find that the resulting heat fluxes are very similar to those between two bulk silicon dioxide surfaces when the gap size is reduced to be comparable to that of the film thickness. This interesting effect is understood on the basis of detailed computational analysis, which shows that the NF-RHT in gaps comparable to film thickness is completely dominated by the contributions from surface phonon-polaritons whose effective skin depth is comparable to the film thickness. These results are expected to hold true for various dielectric surfaces where heat transport is dominated by surface phonon-polaritons and have important implications for near-field based thermo photovoltaic devices and for near-field based thermal management.

  14. Effect of Confinement on Glass Transition Behavior in Polymeric Nanotubes and Nanorods: Comparison of DSC and Fluorescence Measurements

    NASA Astrophysics Data System (ADS)

    Tan, Anthony; Torkelson, John

    2014-03-01

    The effects of nanoscale confinement on the glass transition temperature, Tg, and related behavior are studied in polystyrene nanotubes and nanorods made using anodized aluminum oxide templates. Tube thickness as small as 19 nm has been achieved by melt infiltration methods. Substantial Tg reductions are observed with both DSC and fluorescence measurements of nanotubes supported by the templates, with confinement effects being comparable in magnitude to those obtained via ellipsometry and fluorescence for supported polymer films. Free-standing nanotubes can also be characterized by DSC, yielding much larger Tg reductions than observed in supported nanotubes. Effects of confinement on fragility and physical aging in the supported polystyrene nanotubes and nanorods will also be discussed.

  15. A real-time simulation system of wind power based on LabVIEW DSC module and Matlab\\/Simulink

    Microsoft Academic Search

    Li Nailu; Lv Yuegang; Xi Peiyu

    2009-01-01

    The paper successful integrates LabVIEW DSC module and Matlab\\/Simulink with wind power generation strategy to develop a real-time simulation system of wind power. With this system, a whole process of wind power generation can be viewed easily, legibly and intuitively. So that this system could be used for academical research without the cost of wind turbine and other devices in

  16. Crystal structures, spectroscopic, TG and DSC studies of lanthanide picrate complexes with 4-methylmorpholine N-oxide (MMNO)

    Microsoft Academic Search

    L. C. Fernandes; J. R. Matos; L. B. Zinner; G. Vicentini; J. Zukerman-Schpector

    2000-01-01

    The crystal structures, IR absorption spectra, emission spectrum of the europium compound, TG and DSC analyses of Ln(pic)3·MMNO·2H2O (pic=picrate, Ln=La, Nd, Eu) complexes are reported. The crystals that were grown from methanolic solutions, are isomorphous belonging to the triclinic space group P1?. The Ln ions are coordinated to nine oxygen atoms, six of the picrate moieties, one of the MMNO

  17. DSC measurements on experimental TGDDM/DDS resin systems: The influence of variations in resin composition and catalyst content

    NASA Astrophysics Data System (ADS)

    Vanderhoeven, W.

    1990-07-01

    DSC measurements were performed on 17 resin mixtures, of which the basic constituents were Tetradiglycidyl Diaminodiphenylmethane (TGDDM) and Diglycidyl Ether of Bisphenol A (DGEBA) epoxies and Diaminodiophenylsulfone (DDS) hardener. The DDS/TGDDM and DGEBA/TGDDM ratios were systematically varied. In addition, for some of the mixtures small amounts of catalyst (0.2 and 2 weight percent) were added. The mixtures were cured in the DSC during a scan at constant heating rate (10 C/min). From the results the reaction onset temperature, the peak temperature(s) and the heat of reaction were determined. A second DSC scan was performed to determine the glass transition temperatures of the cured resin systems. The results showed that the effect of the DDS/TGDDM ratio strongly depends on the catalyst content. By increasing the catalyst content, the curing reactions are shifted to lower temperatures and become exothermic. The highest glass transition temperatures were measured for mixtures with 0.2 weight percent catalyst.

  18. Adsorption-induced conformational changes of proteins onto ceramic particles: Differential scanning calorimetry and FTIR analysis

    Microsoft Academic Search

    Natascha Brandes; Petra B. Welzel; Carsten Werner; Lothar W. Kroh

    2006-01-01

    Three model proteins, bovine serum albumin, hen's egg lysozyme and bovine serum fibrinogen, were adsorbed from aqueous solution onto finely dispersed ceramic particles, namely different kinds of alumina and hydroxyapatite particles. The influence of adsorption on protein secondary structure was investigated. The FTIR spectroscopic findings were compared with the results of DSC measurements. In almost all cases it was found

  19. The use of differential scanning calorimetry to study the effects of gentamycin on fibrous collageneous membranes

    Microsoft Academic Search

    E. Siapi; T. Mavromoustakos; V. Trandafir; B. Albu; P. Budrugeac

    2005-01-01

    The protein collagen is the most predominant and important protein of the skin and therefore its physicochemical and thermal properties are important to be known. DSC has been applied in order to study the thermal changes caused by using different concentrations of the gentamycin antibiotic in fibrous membranes FM, named AMATCOL at different scanning rates. The thermal effect consisting of

  20. Differential scanning calorimetry and a thermogravimetric analysis of nanozirconia-based powder systems

    NASA Astrophysics Data System (ADS)

    Kanaki, A. V.; Buyakova, S. P.; Volkov, S. A.; Kulkov, S. N.

    2011-05-01

    Results obtained from differential scanning calorimetry and a thermogravimetric analysis of zirconia-based nanocrystalline powder systems are presented. Heating is found to cause intense mass loss that increases with increase in the MgO content. Differential scanning calorimetry has revealed that the total energy expended for reactions involved in the powder heating process increases with increase in the MgO content. The heated powders are characterized by desorption of water. For 10 wt. % MgO, residual nitrates are seen to decompose into NO2, N2O, or NO.

  1. Synthesis and Thermal Behavior of Silica?Graft?Polypropylene Nanocomposites Studied by Step?Scan DSC and TGA

    Microsoft Academic Search

    Kang Zheng; XiaYin Yao; XingYou Tian; Lin Chen; Hao He; Yong Li

    2006-01-01

    Silica graft poly(propylene) (silica?g?PP) nanocomposites were successfully prepared by radical grafting copolymerization and ring?opening reaction. Their thermal properties were studied by step?scan differential scanning calorimetry (SDSC) and thermogravimetric analysis (TGA). The exothermic peaks in the IsoK baseline (Cp,IsoK, nonreversing signal) of SDSC reveal that PP and silica?g?PP nanocomposites undergo melting?recrystallization?remelting during heating. The peak temperatures of recrystallization and remelting shift

  2. Thermal diffusivity measurements in organic liquids using transient thermal lens calorimetry

    E-print Network

    Harilal, S. S.

    Thermal diffusivity measurements in organic liquids using transient thermal lens calorimetry C. V. Thermal diffusivity measurements are carried out in certain organic liquids using the pulsed dual beam thermal lens technique. The 532 nm pulses from a frequency doubled Q-switched Nd:YAG laser are used

  3. Cluster calorimetry by femtosecond stimulated emission pumping: Excitation and evaporative cooling of I2

    E-print Network

    Neumark, Daniel M.

    Cluster calorimetry by femtosecond stimulated emission pumping: Excitation and evaporative cooling 2002 Femtosecond stimulated emission pumping has been employed as a technique to prepare small clusters with well-known amounts of internal excitation. In this way I2 (CO2)4,5 clusters are prepared with 0.58 to 0

  4. 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…

  5. 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...

  6. 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.

  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. 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. [Medical Physics Unit, McGill University, Montreal, Quebec, H3G-1A4 (Canada); Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114 (United States); Medical Physics Unit, McGill University, Montreal, Quebec, H3G-1A4 (Canada); Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114 (United States); Medical Physics Unit, McGill University, Montreal, Quebec, H3G-1A4 (Canada)

    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.

  9. Binding of globular proteins to lipid membranes studied by isothermal titration calorimetry and fluorescence

    Microsoft Academic Search

    Mariana N Dimitrova; Hideo Matsumura; Nelly Terezova; Vassil Neytchev

    2002-01-01

    The interactions of bovine serum albumin, lysozyme and cytochrome c with phosphatidylcholine liposomes in liquid crystalline phase have been investigated using isothermal titration calorimetry in combination with steady state, and fluorescence measurements. Calorimetric titration studies of the binding of liposomes to the protein species indicate in all cases exothermic processes with single binding sites in the protein molecule. Distinct saturation

  10. Modulated differential scanning calorimetry: isothermal cure and vitrification of thermosetting systems

    Microsoft Academic Search

    G. Van Assche; A. Van Hemelrijck; H. Rahier; B. Van Mele

    1995-01-01

    Modulated differential scanning calorimetry (MDSC) is used to study simultaneously the evolution of heat flow and heat capacity for the isothermal cure of thermosetting systems. A stepwise decrease in the heat capacity is observed. For the organic resins studied, it is shown that the glass transition temperature of the curing resin reaches the cure temperature at half of the decrease

  11. Relationship Between Flame Length and Fireline Intensity Obtained by Calorimetry at Laboratory Scale

    Microsoft Academic Search

    Toussaint Barboni; Frédéric Morandini; Lucile Rossi; Thierry Molinier; Paul-Antoine Santoni

    2012-01-01

    The difficulties in measuring Byram's fireline intensity have led many researchers to derive an empirical relation between the fireline intensity and flame length, which is easier to measure at the practical (firefighting) level. In this article, we address both the estimation of Byram's fireline intensity by comparison with oxygen consumption calorimetry (OC) measurement and the test of formulations for fireline

  12. Final Technical Report �¢���� CMS FAST OPTICAL CALORIMETRY

    SciTech Connect

    David R Winn

    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.

  13. An electrospray technique for hyperquenched glass calorimetry studies: Propylene glycol and di-n-butyl phthalate

    E-print Network

    Angell, C. Austen

    An electrospray technique for hyperquenched glass calorimetry studies: Propylene glycol and di-bonded liquid, propylene glycol, PG and a Van der Waals liquid, di-n-butyl phthalate DBP. Using a fictive question of sub-Tg annealing effects. We find the `shadow' glass transition, (an annealing prepeak) seen

  14. NorLeu3-Angiotensin (1-7) [DSC127] as a Therapy for the Healing of Diabetic Foot Ulcers

    PubMed Central

    Rodgers, Kathleen E.; Bolton, Laura L.; Verco, Shelagh; diZerega, Gere S.

    2015-01-01

    Significance: Diabetes is a disorder that is well known to delay wound repair resulting in the formation of colonized chronic wounds. Over their lifetime, diabetic patients have a 25% incidence of foot ulcers (DFUs), which contribute to increased risk of morbidity, including osteomyelitis and amputations, and increased burden to the healthcare system. Recent Advances: The only active product approved for the treatment of diabetic ulcers, Regranex®, is not widely used due to minimal proven efficacy and recent warnings added to the Instructions for Use. A novel topical agent that accelerates healing and increases the proportion of fully healed DFUs, DSC127 [aclerastide; active ingredient, NorLeu3-angiotensin (1-7) (NorLeu3-A(1-7))], is recruiting patients in Phase III clinical trials (NCT01830348 and NCT01849965). NorLeu3-A(1-7) is an analog of the naturally occurring peptide, angiotensin 1-7. The mechanisms of action include induction of progenitor proliferation, accelerated vascularization, collagen deposition, and re-epithelialization. Critical Issues: Current modalities for the treatment of DFUs include strict offloading, bandaging, debridement and, on a limited basis, application of Regranex. Novel potent therapies are needed to combat this significant burden to the diabetic patient and the healthcare system. Future Direction: Preclinical and clinical research shows that DSC127 is highly effective in the closure of diabetic wounds and is superior to Regranex in animal studies. Clinical development of DSC127 as a topical agent for the healing of DFU is underway. Further investigation into the mechanisms by which this product accelerates healing is warranted. PMID:26029484

  15. Physical-chemical characterization and stability study of alpha-trypsin at pH 3.0 by differential scanning calorimetry.

    PubMed

    Santos, A M C; Santana, M A; Gomide, F T F; Miranda, A A C; Oliveira, J S; Boas, F A S Vilas; Vasconcelos, A B; Bemquerer, M P; Santoro, M M

    2008-04-01

    alpha-Trypsin is a serine-protease with a polypeptide chain of 223 amino acid residues and six disulfide bridges. It is a globular protein with predominance of antiparallel ss-sheet secondary structure and it has two domains with similar structures. In the present work, a stability study of alpha-trypsin in the acid pH range was performed and some physical-chemical denaturation parameters were measured by using differential scanning calorimetry (DSC). The alpha-trypsin has a shelf-life (t(95%)) of about 10 months at pH 3.0 and 4 degrees C and its hydrolysis into the psi-trypsin isoform is negligible during 6 months. The observed ratio DeltaH(cal)/DeltaH(vH) is close to unity, which suggests the occurrence of a two-state transition. At pH 3.0, alpha-trypsin unfolded with T(m) = 325.9 K and DeltaH = 99.10 kcal mol(-1), and the change in heat capacity between the native and unfolded forms of the protein was estimated to be 1.96+/-0.18 kcal mol(-1)K(-1). The stability of alpha-trypsin calculated at 298 K was DeltaG(U)=6.10 kcal mol(-1) at pH 3.0. These values are in the range expected for a small globular protein. These results show that the thermodynamic parameters of unfolding of beta-trypsin do not change substantially after its conversion to alpha-trypsin. PMID:18243299

  16. Application of density functional theory in combination with FTIR and DSC to characterise polymer drug interactions for the preparation of sustained release formulations between fluvastatin and carrageenans.

    PubMed

    Karavas, Evangelos; Koutris, Efthymios; Papadopoulos, Anastasios G; Sigalas, Michael P; Nanaki, Stavroula; Papageorgiou, George Z; Achilias, Dimitris Z; Bikiaris, Dimitrios N

    2014-05-15

    In the present study, ?- and ?-carrageenans were used as appropriate carriers for sustained release formulations of fluvastatin drug. From viscosity measurements, it was found that both carrageenans can give miscible blends with fluvastatin due to the interactions between the sulfate groups of carrageenans and hydroxyl groups of fluvastatin. This was predicted by computational analysis using density functional theory and proved by FTIR spectroscopy. These interactions, which are in higher intensity using ?-carrageenan, lead to the formation of complexes between polymeric matrices and fluvastatin drug. DSC experiments also confirmed that miscible blends between carrageenans and fluvastatin can be formed since in all concentrations only one glass transition temperature was recorded. Fluvastatin release depends on the drug content and in all formulations of ?-carrageenans containing 10, 25 and 50 wt% drug, almost sustained release profiles were observed. Fluvastatin/carrageenan complexes have lower dissolution profiles compared with physical mixtures. Polymer swelling seems to be the dominant drug release mechanism. Besides to neat ?- and ?-carrageenans, their blends can be also used as effective matrices for sustained release. PMID:24613179

  17. Thermal decomposition study of menthyl-glycoside by TGA\\/SDTA, DSC and simultaneous Py-GC–MS analysis

    Microsoft Academic Search

    Wan-cui Xie; Jian Tang; Xiao-hong Gu; Chang-rong Luo; Guang-yu Wang

    2007-01-01

    To develop thermal stable flavor, a glycosidic bond flavor precursor of menthyl-?-d-glucopyranoside (MGLY) was synthesized by the modified Koenigs–Knorr reaction. The thermal decomposition process and pyrolysis products of the glycoside were investigated by thermo-gravimetric and simultaneously differential thermal analysis (TGA\\/SDTA), differential scanning calorimeter (DSC) and on-line pyrolysis-gas chromatography–mass spectroscopy (Py-GC–MS). TGA\\/SDTA gave the TG–DTG and DTA curves simultaneously, the TG–DTG

  18. Electromagnetic Calorimetry at Hadronic Colliders:. Status and Perspectives

    NASA Astrophysics Data System (ADS)

    Camporesi, Tiziano

    2004-08-01

    In this paper the electromagnetic calorimeters of the large LHC experiments, CMS and ATLAS, will be briefly described as representatives of today's state of the art. Accent will be put on the features where these calorimeters have been innovative and on the challenges that the goal of the detection of a narrow resonance on top of a huge background (like a light Higgs boson decaying into ??) poses on the practical side. The implication of an LHC upgrade (SLHC) are discussed. Finally some speculation will be put forward on the possible electromagnetic calorimeter and detector structure for a future Very Large Hadron Collider (VLHC) with instantaneous luminosities in excess of 1035 cm-2s-1 and center of mass energies exceeding 100 TeV.

  19. SuperNEMO double beta decay experiment

    E-print Network

    A. S. Barabash

    2011-12-09

    SuperNEMO is a next-generation double beta decay experiment based on the successful tracking plus calorimetry design approach of the recently stopped NEMO3 experiment. SuperNEMO can study a range of isotopes, but the baseline isotope is $^{82}$Se. The total isotope mass will be 100--200 kg. A sensitivity to a $0\

  20. Characterisation and evaluation of the environmental impact on historical parchments by differential scanning calorimetry

    Microsoft Academic Search

    Elena Badea; Giuseppe Della Gatta; Petru Budrugeac

    2011-01-01

    Our recent developments concerning the assessment of parchments deterioration using DSC are reported. Measurements performed\\u000a on samples in excess water conditions, in static air and gas flow provided qualitative and quantitative information on parchment\\u000a ageing and deterioration at microscopic and mesoscopic level, when assembly of fibres\\/fibrils is weakened, partially and eventually\\u000a completely lost, and at molecular level, when triple helix

  1. 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.

  2. 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 (?cp) 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.

  3. Radiation damage study for silicon calorimetry: Summary of first year's activity

    SciTech Connect

    Russ, J.S.

    1988-01-01

    In the first contract year of this activity at Carnegie-Mellon we have had two major objectives. These were to devise and test a non-intrusive means to measure the energy and spatial profiles of the neutrons generated in a hadronic cascade at high energy; and to study the calibration systematics of silicon diode detectors as a prelude to their evaluation for SSC calorimetry. These objectives have been carried out, as are described in this paper. In addition we have recoded the ORNL detector simulation program HETC to operate on a VAX and are working on the conversion of the low energy neutron transport program MORSE. These programs are used heavily at Oak Ridge (Gabriel and coworkers) for cascade studies. For silicon calorimetry one wants to have more control over the energy deposition routines, especially in MORSE. Unfortunately, MORSE is heavily-laden with machine code, and its conversion is going slowly. 11 refs., 5 figs.

  4. Method for direct deconvolution of heat signals in transient adsorption calorimetry

    NASA Astrophysics Data System (ADS)

    Wolcott, Christopher A.; Campbell, Charles T.

    2015-03-01

    A method of heat signal analysis is presented for transient adsorption calorimetries including single crystal adsorption calorimetry (SCAC) which uses fast Fourier transforms (FFT) to determine the instrument response function and deconvolute the heat-versus-time signals. The method utilizes a heat signal generated by a laser pulse of known power-versus-time to extract the instrument response function for the calorimeter. The instrument response function is then used to extract the heat power signal from a molecular beam heat pulse of unknown intensity. This method allows for the extraction of the total heat deposited by the molecular beam pulse without any kinetic modeling even in the event of complex reaction dynamics. This method is compared to previous methods used to analyze SCAC data using example data from the two-step dissociative adsorption of methyl iodide on Pt(111). It is found to be equally accurate for extracting total heats and simpler to perform than the previous methods.

  5. Differential Scanning Calorimetry Determination of Gelatinization Rates in Different Starches due to Microwave Heating

    Microsoft Academic Search

    Matrid Ndife; Gülüm ?umnu; Levent Bay?nd?rl?

    1998-01-01

    Wheat, corn and rice starch dispersions having water–starch ratios of 1.0:1.0, 1.5:1.0 and 2.0:1.0 (w\\/w) were heated in a microwave oven for 15 to 30 s and the degree of gelatinization was determined by differential scanning calorimetry. During 15 to 25 s of microwave heating, corn starch gelatinization rates were significantly lower and slower than wheat and rice starch rates.

  6. The hydration pressure between lipid bilayers. Comparison of measurements using x-ray diffraction and calorimetry.

    PubMed Central

    Simon, S. A.; Fink, C. A.; Kenworthy, A. K.; McIntosh, T. J.

    1991-01-01

    The hydration pressure between dipalmitoyl phosphatidyl-N,N-dimethylethanolamine (DPPE-Me2) bilayers has been analyzed by both x-ray diffraction measurements of osmotically stressed liposomes and by differential scanning calorimetry. By the x-ray method, we obtain a magnitude (Po) and decay length (lambda) for the hydration pressure which are both quite similar to those found for bilayers of other zwitterionic lipids, such as phosphatidylcholines. That is, x-ray analysis of DPPE-Me2 in the gel phase gives lambda = 1.3 A, the same as that previously measured for the analogous gel phase lipid dipalmitoylphosphatidylcholine (DPPC), and Po = 3.9 x 10(9) dyn/cm2, which is in excellent agreement with the value of 3.6 x 10(9) dyn/cm2 calculated from the measured Volta potential of DPPE-Me2 monolayers in equilibrium with liposomes. These results indicate that the removal of one methyl group to convert DPPC to DPPE-Me2 does not markedly alter the range or magnitude of the hydration pressure. Calorimetry shows that the main gel to liquid-crystalline phase transition temperature of DPPE-Me2 is approximately constant for water contents ranging from 80 to 10 water molecules per lipid molecule, but increases monotonically with decreasing water content below 10 waters per lipid. A theoretical fit to these temperature vs. water content data predicts lambda = 6.7 A. The difference in observed values of lambda for x-ray and calorimetry measurements can be explained by effects on the thermograms of additional intra- and intermolecular interactions which occur at low water contents where apposing bilayers are in contact. We conclude that, although calorimetry provides important data on the energetics of bilayer hydration, it is difficult to obtain quantitative information on the hydration pressure from this technique. PMID:2049518

  7. Standard molar enthalpy of formation of 4-iodobenzoic acid by static and rotating-bomb calorimetry

    Microsoft Academic Search

    M. A. V. Ribeiro da Silva; M. L. C. C. H. Ferrão; I. M. S. Costa

    1999-01-01

    The standard (po= 0.1 MPa) molar enthalpy of combustion of 4-iodobenzoic acid, at T= 298.15 K, was measured by static-bomb and rotating-bomb calorimetry, from which the standard molar enthalpy of formation, in the crystalline state, was derived.The values obtained confirm that 4-iodobenzoic acid is a satisfactory test substance for combustion of organo-iodine compounds. Using a literature value for its standard

  8. Methods Used to Process Data from Indirect Calorimetry and Their Application to VO2MAX

    Microsoft Academic Search

    Robert Robergs; Angus Burnett

    2003-01-01

    Our purpose was to provide objective evidence in support of recommendations for how to process data in gas exchange indirect calorimetry (GEIC). A computer generated data set, devoid of biological variability and measurement error, was used to assess the error in data processing methods of a) 0.25, 0.5 and 1.0 min time averages, b) a 7 breath average, and c)

  9. Pathogenesis of obesity and diabetes mellitus: insights provided by indirect calorimetry in humans

    Microsoft Academic Search

    G. Perseghin

    2001-01-01

    Energy homeostasis is the balance between energy intake and energy expenditure. Assessment of energy intake is unreliable,\\u000a especially in obese individuals. On the contrary it is possible to assess energy expenditure by means of different techniques.\\u000a In this review, the contributions of indirect calorimetry to its assessment and to the comprehension of the pathogenic mechanisms\\u000a of obesity and diabetes mellitus

  10. Calorimetry of the Pd-D2O system: from simplicity via complications to simplicity

    Microsoft Academic Search

    Martin Fleischmann; Stanley Pons

    1993-01-01

    We present here one aspect of our recent research on the calorimetry of the Pd-D2O system which has been concerned with high rates of specific excess enthalpy generation (>1 kW cm-3 at temperatures close to (or at) the boiling point of the electrolyte solution. This has led to a particularly simple method of deriving the rate of excess enthalpy production

  11. A scanning AC calorimetry technique for the analysis of nano-scale quantities of materials.

    PubMed

    Xiao, Kechao; Gregoire, John M; McCluskey, Patrick J; Vlassak, Joost J

    2012-11-01

    We present a scanning AC nanocalorimetry method that enables calorimetry measurements at heating and cooling rates that vary from isothermal to 2 × 10(3) K/s, thus bridging the gap between traditional scanning calorimetry of bulk materials and nanocalorimetry. The method relies on a micromachined nanocalorimetry sensor with a serpentine heating element that is sensitive enough to make measurements on thin-film samples and composition libraries. The ability to perform calorimetry over such a broad range of scanning rates makes it an ideal tool to characterize the kinetics of phase transformations or to explore the behavior of materials far from equilibrium. We demonstrate the technique by performing measurements on thin-film samples of Sn, In, and Bi with thicknesses ranging from 100 to 300 nm. The experimental heat capacities and melting temperatures agree well with literature values. The measured heat capacities are insensitive to the applied AC frequency, scan rate, and heat loss to the environment over a broad range of experimental parameters. PMID:23206083

  12. A scanning AC calorimetry technique for the analysis of nano-scale quantities of materials

    NASA Astrophysics Data System (ADS)

    Xiao, Kechao; Gregoire, John M.; McCluskey, Patrick J.; Vlassak, Joost J.

    2012-11-01

    We present a scanning AC nanocalorimetry method that enables calorimetry measurements at heating and cooling rates that vary from isothermal to 2 × 103 K/s, thus bridging the gap between traditional scanning calorimetry of bulk materials and nanocalorimetry. The method relies on a micromachined nanocalorimetry sensor with a serpentine heating element that is sensitive enough to make measurements on thin-film samples and composition libraries. The ability to perform calorimetry over such a broad range of scanning rates makes it an ideal tool to characterize the kinetics of phase transformations or to explore the behavior of materials far from equilibrium. We demonstrate the technique by performing measurements on thin-film samples of Sn, In, and Bi with thicknesses ranging from 100 to 300 nm. The experimental heat capacities and melting temperatures agree well with literature values. The measured heat capacities are insensitive to the applied AC frequency, scan rate, and heat loss to the environment over a broad range of experimental parameters.

  13. 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.

  14. Application of fire calorimetry to understand factors affecting flammability of cellulosic material: pine needles, tree leaves and chipboard 

    E-print Network

    Jervis Calle, Freddy Xavier; Calle, Freddy Xavier Jervis; Jervis, Freddy Xavier

    2012-11-29

    Calorimetry, the science of measuring heat from chemical reactions and physical changes, is one to the most valuable tools fire safety engineering have at their disposal. Calorimetric devices such as the cone calorimeter ...

  15. Application of fire calorimetry to understand factors affecting flammability of cellulosic material: Pine needles, tree leaves and chipboard 

    E-print Network

    Jervis, Freddy Xavier

    2012-01-01

    Calorimetry, the science of measuring heat from chemical reactions and physical changes, is one to the most valuable tools fire safety engineering have at their disposal. Calorimetric devices such as the cone calorimeter ...

  16. 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

    2014-01-01

    The suitable size hydrophobic cavity and monochlorotriazinyl group as a reactive anchor make MCT-?-CD to be widely used in fabric finishing. In this paper, the inclusion complexes of monochlorotriazinyl-beta-cyclodextrin (MCT-?-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-?-CD and their inclusion complexes. Four isomers of trisubstituted MCT-?-CD are designed and DFT calculations reveal that 1,3,5-trisubstituted MCT-?-CD has the lowest energy and can be considered as main component of MCT-?-CD. The ground-state geometries, vibrational wavenumbers, IR and Raman intensities of MCT-?-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-?-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-?-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-?-CD and has weak interaction with MCT-?-CD. This spectroscopy conclusion is consistent with theoretical predicted structure. PMID:24103228

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

    The suitable size hydrophobic cavity and monochlorotriazinyl group as a reactive anchor make MCT-?-CD to be widely used in fabric finishing. In this paper, the inclusion complexes of monochlorotriazinyl-beta-cyclodextrin (MCT-?-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-?-CD and their inclusion complexes. Four isomers of trisubstituted MCT-?-CD are designed and DFT calculations reveal that 1,3,5-trisubstituted MCT-?-CD has the lowest energy and can be considered as main component of MCT-?-CD. The ground-state geometries, vibrational wavenumbers, IR and Raman intensities of MCT-?-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-?-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-?-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-?-CD and has weak interaction with MCT-?-CD. This spectroscopy conclusion is consistent with theoretical predicted structure.

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

    NASA Astrophysics Data System (ADS)

    Szostak, El?bieta; Migda?-Mikuli, Anna; Bernard, Pawe?

    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 Tc2c = 218 K and phase Cr 2 ? phase Cr 1 at Tc1c = 246 K. X-ray single crystal diffraction studies of [Cd(DMSO)6](BF4)2 have shown that these transitions are related to a crystal symmetry reduction from an orthorhombic crystallographic system (Fdd2, No. 43) to a monoclinic one (Cc, No. 9). The [Cd(DMSO)6](BF4)2 compound undergoes also series of reversible high temperature phase transitions but they are not a subject of this work and will be presented in our next paper. The characteristic changes of the FT-FIR, FT-MIR and FT-RS spectra of [Cd(DMSO)6](BF4)2 at the phase transitions' temperatures confirmed that phase transitions phase Cr 3 ? phase Cr 2 ? phase Cr 1 are related to the crystal structure change. It was also found that the reorientation of the BF4- anions and DMSO ligands freezes below 218 K.

  19. 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 (?H(‡)) and Eyring transition state entropies (?S(‡)). 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 (?H(25°C) = -41.6 ± 1.2 kcal/mol in 150 mM KCl) and the transition state is enthalpically barrierless (?H(‡) = -0.6 ± 0.5). These parameters are significantly positively shifted in magnesium (?H(25°C) = -20.5 ± 2.1 kcal/mol, ?H(‡) = 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. PMID:22058128

  20. Effects of particle size on the desorption kinetics of water from Beulah-Zap lignite coal: Differential scanning calorimetry results

    SciTech Connect

    Dang, Yuhong; Malhotra, V.M. [Southern Illinois Univ., Carbondale, IL (United States); Vorres, K.S. [Argonne National Lab., IL (United States). Chemistry Div.

    1996-03-01

    The drying kinetics of water from three particle-sized Beulah-Zap lignite coal samples were probed using the differential scanning calorimetry technique at 295 < T < 480 K. The measurements undertaken under flowing N{sub 2} gas environment indicate that water is lost from this coal by two independent but simultaneously operative kinetic mechanisms. Our results suggest that the unimolecular decay kinetics are obeyed by those water molecules which are near the mouths of large pores and/or surround the coal particles. Most of the water, about 80% of the water lost in our experiments, was removed via a 2nd-order diffusion mechanism. As expected, the desorption activation energies of the 2nd-order diffusion kinetics were much larger than the decay mechanism`s activation energies. Our results also suggest, at least for particle sizes < 841 {mu}m, < 106 {mu}m, and < 37 {mu}m, that the coal particle size has little effect on the desorption activation barriers.

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

    PubMed Central

    Vander Meulen, Kirk A.; Butcher, Samuel E.

    2012-01-01

    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 (?H‡) and Eyring transition state entropies (?S‡). 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 (?H25°C?=??41.6?±?1.2?kcal/mol in 150?mM KCl) and the transition state is enthalpically barrierless (?H‡?=??0.6?±?0.5). These parameters are sigificantly positively shifted in magnesium (?H25°C?=??20.5?±?2.1?kcal/mol, ?H‡?=?7.3?±?2.2?kcal/mol in 0.5?mM MgCl2). 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. PMID:22058128

  2. Characterization of polymer matrix and low melting point solder for anisotropic conductive film

    Microsoft Academic Search

    Yong-Sung Eom; Ji-Won Baek; Jong-Tae Moon; Jae-Do Nam; Jong-Min Kim

    2008-01-01

    The chemo-rheological mechanisms of a polymer matrix and a low melting point solder for an anisotropic conductive film (ACF) have been characterized. For the material characterization of the polymer matrix and solder, a differential scanning calorimetry (DSC) and a dynamic mechanical analyzer (DMA) experiments were conducted. The conversion and viscosity of the polymer matrix was observed by DSC and DMA,

  3. 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.

  4. Temperature-modulated DSC using higher harmonics of the Fourier transform 1 Authored by a contractor of the US Government under the contract No. DE-AC05-96OR22464. Accordingly, the US Government retains a non-exclusive, royalty-free license to publish, or reproduce the published form of this contribution, or allow others to do so, for US Government purposes. 1

    Microsoft Academic Search

    R Androsch; B Wunderlich

    1999-01-01

    In this paper, experiments with temperature-modulated calorimetry are described in which use is made of multiple modulation frequencies for the evaluation of the heat capacity. The different harmonics of the Fourier series of the heat-flow rate and heating rate of a single sawtooth-modulation experiment were deconvoluted to extract data pertaining to different frequencies. In the normally employed temperature-modulated differential scanning

  5. Differential Scanning Calorimetry Investigations on Polyvinylidene Fluoride - Fe3O4 Nanocomposites

    NASA Astrophysics Data System (ADS)

    Salinas, Samantha; Jones, Robert; Chipara, Dorina M.; Chipara, Mircea

    2015-03-01

    Nanocomposites of polyvinylidene fluoride (PVDF)-magnetite (Fe3O4) with various weight fractions of nanofiller (0%, 0.2 %, 0.6 %, 1.2%, 2.4 %, 5.8 %, 12 %, 23 %, and 30 %) have been obtained via melt mixing by loading PVDF with Fe3O4 particles (average size 75 nm from Nanostructured & Amorphous Materials, Inc). Thermal stability of PVDF-Fe3O4 has been investigated by TGA in nitrogen. The increase of the thermal stability of PVDF due to the loading with Fe3O4 was quantified by the shift of the temperature at which the (mass) degradation rate is maximum as a function of Fe3O4 content. The effect of the nanofiller on the crystallization of PVDF was investigated by isothermal DSC (TA Instruments, Q500). Non isothermal DSC tests, (at various heating rates ranging from 1 to 25 °C/min) have been used to locate the glass, crystallization, and melting temperatures. The dependence of the glass, crystallization, and melting temperatures on the concentration of nanoparticles is reported and analyzed in detail. The data are critically analyzed within the classical Avrami theory.

  6. Energy storage capacity of reversible liquid phase Diels-Alder reactions as determined by drop calorimetry

    SciTech Connect

    Chung, C.P.

    1983-01-01

    Several Diels-Alder reactions were evaluated as possible candidates for energy storage. The goal was to use simple drop calorimetry to screen reactions and to identify those with high energy storage capacities. The dienes used were furan and substituted furans. The dienophiles used were maleic anhydride and substituted maleic anhydrides. Sixteen reactions have been examined. Three had energy storage capacities that were increased due to reaction (maleic anhydride and 2-methyl furan, maleic anhydride and 2-ethyl furan, maleic anhydride and 2,5-dimethyl furan). The remaining thirteen showed no increase in apparent heat capacity due to reaction.

  7. Survey of the year 2004: literature on applications of isothermal titration calorimetry.

    PubMed

    Ababou, Abdessamad; Ladbury, John E

    2006-01-01

    The market for commercially available isothermal titration calorimeters continues to grow as new applications and methodologies are developed. Concomitantly the number of users (and abusers) increases dramatically, resulting in a steady increase in the number of publications in which isothermal titration calorimetry (ITC) plays a role. In the present review, we will focus on areas where ITC is making a significant contribution and will highlight some interesting applications of the technique. This overview of papers published in 2004 also discusses current issues of interest in the development of ITC as a tool of choice in the determination of the thermodynamics of molecular recognition and interaction. PMID:16220545

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

    PubMed

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

    2015-06-01

    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. PMID:25951890

  9. Thermophysical and thermal optical properties of vanadium by millisecond calorimetry between 300 and 1900 K

    SciTech Connect

    Stanimirovic, A.; Vukovic, G.; Maglic, K. [Inst. of Nuclear Sciences Vinca, Belgrade (Yugoslavia)] [Inst. of Nuclear Sciences Vinca, Belgrade (Yugoslavia)

    1999-01-01

    A variant of millisecond-resolution pulse calorimetry in use at the Institute of Nuclear Sciences Vinca since 1983 involves measuring the specific heat and electrical resistivity of electrical conductors from room temperature to 2,500 K and the hemispherical total emissivity and normal spectral emissivity from about 1,300 K to the same maximum operating temperature. The method was applied successfully to different materials: pure metals, ferrous and nickel-base alloys, reactor materials, and refractory metals in thermal characterization of candidates for thermophysical properties standard reference materials. This paper presents and discusses new data obtained in the study of thermophysical and thermal optical properties of vanadium.

  10. High-temperature calorimetry of (La 1? x Ln x )PO 4 solid solutions

    Microsoft Academic Search

    K. Popa; R. J. M. Konings; T. Geisler

    2007-01-01

    The enthalpy increment of the monazite-type solid solutions of LaPO4 with NdPO4, EuPO4 and GdPO4 has been measured by drop calorimetry at T=1000K. The results show deviations (excess enthalpy) from ideal behaviour that have been interpreted in terms of lattice strains resulting from the ion size effects of substitution of La3+ by Ln3+. For (La0.5Gd)0.5PO4 also the temperature dependence has

  11. Thermal-Diffusivity and Heat-Capacity Measurements of Sandstone at High Temperatures Using Laser Flash and DSC Methods

    NASA Astrophysics Data System (ADS)

    Abdulagatov, I. M.; Abdulagatova, Z. Z.; Kallaev, S. N.; Bakmaev, A. G.; Ranjith, P. G.

    2015-04-01

    The well-known contact-free, laser-flash method was used for measurement of the thermal diffusivity of natural sandstone samples. The experimental procedure was conducted using the microflash apparatus (LFA 457). The measurements have been made over the temperature range from (302.9 to 774.3) K. The isobaric heat capacities of the same sample were measured over the temperature range from (308 to 763) K using DSC 204 F1. Uncertainties are 3 % and 1 % for and , respectively. Measured values of and together with density data were used to calculate the thermal conductivity of sandstone. Theoretically based correlations for the thermal diffusivity (damped harmonic oscillator, DHO) and heat capacity (Debye and Einstein theories) were adopted to accurately represent the measured data. Correlation equations for the thermal diffusivity and heat capacity have been developed using the well-known theoretical asymptotic behavior of and for various temperature ranges (low- and high-temperature limits). The microscopic nature of the effect of temperature on and behavior of sandstone is discussed. Detailed interpretation and testing of the measured property data for sandstone using various existing theoretical and empirical models, in order to check their accuracy, predictive capability, and applicability, are provided.

  12. 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.

  13. Chip Calorimetry for Fast and Reliable Evaluation of Bactericidal and Bacteriostatic Treatments of Biofilms?

    PubMed Central

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

    2010-01-01

    Chip calorimetry is introduced as a new monitoring tool that provides real-time information about the physiological state of biofilms. Its potential for use for the study of the effects of antibiotics and other biocides was tested. Established Pseudomonas putida biofilms were exposed to substances known to cause toxicity by different mechanisms and to provoke different responses of defense and resistance. The effects of these compounds on heat production rates were monitored and compared with the effects of these compounds on the numbers of CFU and intracellular ATP contents. The real-time monitoring potential of chip calorimetry was successfully demonstrated by using as examples the fast-acting poisons formaldehyde and 2,4-dinitrophenol (DNP). A dosage of antibiotics initially increased the heat production rate. This was discussed as being the effect of energy-dependent resistance mechanisms (e.g., export and/or transformation of the antibiotic). The subsequent reduction in the heat production rate was attributed to the loss of activity and the death of the biofilm bacteria. The shapes of the death curves were in agreement with the assumed variation in the levels of exposure of cells within the multilayer biofilms. The new monitoring tool provides fast, quantitative, and mechanistic insights into the acute and chronic effects of a compound on biofilm activity while requiring only minute quantities of the biocide. PMID:19822705

  14. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  16. Interaction of gymnemic acid with cyclodextrins analyzed by isothermal titration calorimetry, NMR and dynamic light scattering.

    PubMed

    Izutani, Yusuke; Kanaori, Kenji; Imoto, Toshiaki; Oda, Masayuki

    2005-12-01

    The physiological phenomenon that the antisweet taste effect of gymnemic acid (GA) is diminished by application of gamma-cyclodextrin (gamma-CD) to the mouth was evaluated at the molecular level using isothermal titration calorimetry, NMR and dynamic light scattering. These analyses showed that GA specifically binds to gamma-CD. Thermodynamic analysis using isothermal titration calorimetry revealed that the association constant of GA and gamma-CD is 10(5)-10(6) m(-1) with favorable enthalpy and entropy changes. The heat capacity change was negative and large, despite the change in accessible surface area upon binding being small. These thermodynamics indicate that the binding is dominated by hydrophobic interactions, which is in agreement with inclusion complex formation of gamma-CD. In addition, NMR measurements showed that in solution the spectra of GA are broad and sharpened by the addition of gamma-CD, indicating that unbound GA is in a water-soluble aggregate that is dispersed when it forms a complex with gamma-CD. Dynamic light scattering showed that the average diameter of unbound GA is > 30 nm and that of GA and gamma-CD complex is 2.2 nm, similar to unbound gamma-CD, supporting the aggregate property of GA and the inclusion complexation of GA by gamma-CD. PMID:16302978

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

    PubMed

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

    2014-01-01

    Any growth or bioconversion in biofilms is accompanied by the release of heat. The heat (in J) is tightly related to the stoichiometry of the respective process via law of Hess, and the heat production rate (in W or J/s) is additionally related to the process kinetics. This heat and the heat production rate can nowadays be measured by modern calorimetry with extremely high sensitivity. Flow-through calorimetry allows the measurement of bioprocesses in biofilms in real time, without the need of invasive sample preparation and disturbing of biofilm processes. Furthermore, it can be applied for long-term measurements and is even applicable to turbid media. Chip or miniaturized calorimeters have the additional advantages of extremely short thermal equilibration times and the requirement of very small amounts of media and chemicals. The precision of flow-through chip calorimeters (about 3 mW/L) allows the detection of early stages of biofilm development (about 10(5) bacteria cm(-2)). PMID:24664840

  18. DSC measurements on sharks

    Microsoft Academic Search

    Reinhard Schubring

    2007-01-01

    Sharks are commonly termed fish, even though they are only distantly related to the classical (bony) fish. What differentiates a shark from a bony fish? Sharks have a spinal column and are thus vertebrates. However, their skeleton is not made of bones, but of cartilage, and together with their nearest relatives the rays and the chimeras they form the class

  19. SU-D-18C-02: Feasibility of Using a Short ASL Scan for Calibrating Cerebral Blood Flow Obtained From DSC-MRI

    SciTech Connect

    Wang, P; Chang, T; Huang, K; Yeh, C; Chien, C; Wai, Y; Lee, T; Liu, H [Department of Medical Imaging and Radiological Sciences, Chang Gung University, Taoyuan County, Taiwan (R.O.C.). (China)

    2014-06-01

    Purpose: This study aimed to evaluate the feasibility of using a short arterial spin labeling (ASL) scan for calibrating the dynamic susceptibility contrast- (DSC-) MRI in a group of patients with internal carotid artery stenosis. Methods: Six patients with unilateral ICA stenosis enrolled in the study on a 3T clinical MRI scanner. The ASL-cerebral blood flow (-CBF) maps were calculated by averaging different number of dynamic points (N=1-45) acquired by using a Q2TIPS sequence. For DSC perfusion analysis, arterial input function was selected to derive the relative cerebral blood flow (rCBF) map and the delay (Tmax) map. Patient-specific CF was calculated from the mean ASL- and DSC-CBF obtained from three different masks: (1)Tmax< 3s, (2)combined gray matter mask with mask 1, (3)mask 2 with large vessels removed. One CF value was created for each number of averages by using each of the three masks for calibrating the DSC-CBF map. The CF value of the largest number of averages (NL=45) was used to determine the acceptable range(< 10%, <15%, and <20%) of CF values corresponding to the minimally acceptable number of average (NS) for each patient. Results: Comparing DSC CBF maps corrected by CF values of NL (CBFL) in ACA, MCA and PCA territories, all masks resulted in smaller CBF on the ipsilateral side than the contralateral side of the MCA territory(p<.05). The values obtained from mask 1 were significantly different than the mask 3(p<.05). Using mask 3, the medium values of Ns were 4(<10%), 2(<15%) and 2(<20%), with the worst case scenario (maximum Ns) of 25, 4, and 4, respectively. Conclusion: This study found that reliable calibration of DSC-CBF can be achieved from a short pulsed ASL scan. We suggested use a mask based on the Tmax threshold, the inclusion of gray matter only and the exclusion of large vessels for performing the calibration.

  20. Feasibility study on using fast calorimetry technique to measure a mass attribute as part of a treaty verification regime

    SciTech Connect

    Hauck, Danielle K [Los Alamos National Laboratory; Bracken, David S [Los Alamos National Laboratory; Mac Arthur, Duncan W [Los Alamos National Laboratory; Santi, Peter A [Los Alamos National Laboratory; Thron, Jonathan [Los Alamos National Laboratory

    2010-01-01

    The attribute measurement technique provides a method for determining whether or not an item containing special nuclear material (SNM) possesses attributes that fall within an agreed upon range of values. One potential attribute is whether the mass of an SNM item is larger than some threshold value that has been negotiated as part of a nonproliferation treaty. While the historical focus on measuring mass attributes has been on using neutron measurements, calorimetry measurements may be a viable alternative for measuring mass attributes for plutonium-bearing items. Traditionally, calorimetry measurements have provided a highly precise and accurate determination of the thermal power that is being generated by an item. In order to achieve this high level of precision and accuracy, the item must reach thermal equilibrium inside the calorimeter prior to determining the thermal power of the item. Because the approach to thermal equilibrium is exponential in nature, a large portion of the time spent approaching equilibrium is spent with the measurement being within {approx}10% of its final equilibrium value inside the calorimeter. Since a mass attribute measurement only needs to positively determine if the mass of a given SNM item is greater than a threshold value, performing a short calorimetry measurement to determine how the system is approaching thermal equilibrium may provide sufficient information to determine if an item has a larger mass than the agreed upon threshold. In previous research into a fast calorimetry attribute technique, a two-dimensional heat flow model of a calorimeter was used to investigate the possibility of determining a mass attribute for plutonium-bearing items using this technique. While the results of this study looked favorable for developing a fast calorimetry attribute technique, additional work was needed to determine the accuracy of the model used to make the calculations. In this paper, the results from the current work investigating the fast calorimetry attribute technique will be presented.

  1. Survey of the year 2005: literature on applications of isothermal titration calorimetry.

    PubMed

    Ababou, Adessamad; Ladbury, John E

    2007-01-01

    Isothermal titration calorimetry (ITC) can provide a full thermodynamic characterization of an interaction. Its usage does not suffer from constraints of molecular size, shape or chemical constitution. Neither is there any need for chemical modification or attachment to solid support. This ease of use has made it an invaluable instrumental resource and led to its appearance in many laboratories. Despite this, the value of the thermodynamic parameterization has, only quite recently, become widely appreciated. Although our understanding of the correlation between thermodynamic data and structural details continues to be somewhat naïve, a large number of publications have begun to improve the situation. In this overview of the literature for 2005, we have attempted to highlight works of interest and novelty. Furthermore, we draw attention to those works which we feel have provided a route to better analysis and increased our ability to understand the meaning of thermodynamic change on binding. PMID:17006876

  2. Thermodynamic signature of secondary nano-emulsion formation by isothermal titration calorimetry.

    PubMed

    Fotticchia, Iolanda; Fotticchia, Teresa; Mattia, Carlo Andrea; Netti, Paolo Antonio; Vecchione, Raffaele; Giancola, Concetta

    2014-12-01

    The stabilization of oil in water nano-emulsions by means of a polymer coating is extremely important; it prolongs the shelf life of the product and makes it suitable for a variety of applications ranging from nutraceutics to cosmetics and pharmaceutics. To date, an effective methodology to assess the best formulations in terms of thermodynamic stability has yet to be designed. Here, we perform a complete physicochemical characterization based on isothermal titration calorimetry (ITC) compared to conventional dynamic light scattering (DLS) to identify polymer concentration domains that are thermodynamically stable and to define the degree of stability through thermodynamic functions depending upon any relevant parameter affecting the stability itself, such as type of polymer coating, droplet distance, etc. For instance, the method was proven by measuring the energetics in the case of two different biopolymers, chitosan and poly-L-lysine, and for different concentrations of the emulsion coated with poly-L-lysine. PMID:25396753

  3. Binding of chrysoidine to catalase: spectroscopy, isothermal titration calorimetry and molecular docking studies.

    PubMed

    Yang, Bingjun; Hao, Fang; Li, Jiarong; Chen, Dongliang; Liu, Rutao

    2013-11-01

    Chrysoidine is an industrial azo dye and the presence of chrysoidine in water and food has become an environmental concern due to its negative effects on human beings. In this work, the interactions between chrysoidine and bovine liver catalase (BLC) were explored. Obvious loss in catalytic activity was observed after incubation of BLC with chrysoidine, and the inhibition effect of BLC was found to be of the non-competitive type. No profound conformational change of BLC occurs in the presence of chrysoidine as revealed by UV-vis absorption, circular dichroism and fluorescence spectroscopy studies. Isothermal titration calorimetry results indicate that catalase has two sets of binding sites for chrysoidine. Further, molecular docking simulations show that chrysoidine is located within the bottleneck in the main channel of the substrate to the active site of BLC, which explain the activity inhibition of BLC by chrysoidine. PMID:24001681

  4. Substrate binding properties of potato tuber ADP-glucose pyrophosphorylase as determined by isothermal titration calorimetry.

    PubMed

    Cakir, Bilal; Tuncel, Aytug; Green, Abigail R; Koper, Kaan; Hwang, Seon-Kap; Okita, Thomas W; Kang, ChulHee

    2015-06-01

    Substrate binding properties of the large (LS) and small (SS) subunits of potato tuber ADP-glucose pyrophosphorylase were investigated by using isothermal titration calorimetry. Our results clearly show that the wild type heterotetramer (S(WT)L(WT)) possesses two distinct types of ATP binding sites, whereas the homotetrameric LS and SS variant forms only exhibited properties of one of the two binding sites. The wild type enzyme also exhibited significantly increased affinity to this substrate compared to the homotetrameric enzyme forms. No stable binding was evident for the second substrate, glucose-1-phosphate, in the presence or absence of ATP?S suggesting that interaction of glucose-1-phosphate is dependent on hydrolysis of ATP and supports the Theorell-Chance bi bi reaction mechanism. PMID:25953126

  5. DNA heats up : Energetics of genome ejection from phage revealed by isothermal titration calorimetry

    E-print Network

    Jeembaeva, Meerim; Castelnovo, Martin; Evilevitch, Alex

    2010-01-01

    Most bacteriophages are known to inject their double-stranded DNA into bacteria upon receptor binding in an essentially spontaneous way. This downhill thermodynamic process from the intact virion toward the empty viral capsid plus released DNA is made possible by the energy stored during active packaging of the genome into the capsid. Only indirect measurements of this energy have been available until now using either single-molecule or osmotic suppression techniques. In this paper, we describe for the first time the use of isothermal titration calorimetry to directly measure the heat released (or equivalently the enthalpy) during DNA ejection from phage lambda, triggered in solution by a solubilized receptor. Quantitative analyses of the results lead to the identification of thermodynamic determinants associated with DNA ejection. The values obtained were found to be consistent with those previously predicted by analytical models and numerical simulations. Moreover, the results confirm the role of DNA hydrat...

  6. Thermophysical analysis of II-VI semiconductors by PPE calorimetry and lock-in thermography

    SciTech Connect

    Streza, M.; Dadarlat, D. [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath, 400293 Cluj-Napoca (Romania)] [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath, 400293 Cluj-Napoca (Romania); Strza?kowski, K. [Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100 (Poland)] [Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100 (Poland)

    2013-11-13

    An accurate determination of thermophysical properties such as thermal diffusivity, thermal effusivity and thermal conductivity is extremely important for characterization and quality assurance of semiconductors. Thermal diffusivity and effusivity of some binary semiconductors have been investigated. Two experimental techniques were used: a contact technique (PPE calorimetry) and a non contact technique (lock-in thermography). When working with PPE, in the back (BPPE) configuration and in the thermally thick regim of the pyroelectric sensor, we can get the thermal diffusivity of the sample by performing a scanning of the excitation frequency of radiation. Thermal effusivity is obtained in front configuration (sensor directly irradiated and sample in back position) by performing a thickness scan of a coupling fluid. By using the lock-in thermography technique, the thermal diffusivity of the sample is obtained from the phase image. The results obtained by the two techniques are in good agreement. Nevertheless, for the determination of thermal diffusivity, lock-in thermography is preferred.

  7. Spacecraft calorimetry as a test of the dark matter scattering model for flyby anomalies

    E-print Network

    Stephen L. Adler

    2010-12-20

    In previous papers we have shown that scattering of spacecraft nucleons from dark matter gravitationally bound to the earth gives a possible explanation of the flyby velocity anomalies. In addition to flyby velocity changes arising from the average over the scattering cross section of the collision-induced nucleon velocity change, there will be spacecraft temperature increases arising from the mean squared fluctuation of the collision-induced velocity change. We give here a quantitative treatment of this effect, and suggest that careful calorimetry on spacecraft traversing the region below 70,000 km where the flyby velocity changes take place could verify, or at a minimum place significant constraints, on the dark matter scattering model.

  8. Spacecraft calorimetry as a test of the dark matter scattering model for flyby anomalies

    E-print Network

    Adler, Stephen L

    2009-01-01

    In previous papers we have shown that scattering of spacecraft nucleons from dark matter gravitationally bound to the earth gives a possible explanation of the flyby velocity anomalies. In addition to flyby velocity changes arising from the average over the scattering cross section of the collision-induced nucleon velocity change, there will be spacecraft temperature increases arising from the mean squared fluctuation of the collision-induced velocity change. We give here a quantitative treatment of this effect, and suggest that careful calorimetry on spacecraft traversing the region below 70,000 km where the flyby velocity changes take place could verify, or at a minimum place significant constraints, on the dark matter scattering model.

  9. Chip-calorimetry provides real time insights into the inactivation of biofilms by predatory bacteria.

    PubMed

    Buchholz, F; Lerchner, J; Mariana, F; Kuhlicke, U; Neu, T R; Harms, H; Maskow, T

    2012-01-01

    Control or removal of undesired biofilms has frequently been found to be quite difficult. In addition to biocidal or antibiotic chemicals or materials designed to prevent biofouling, biological control agents appear to be promising. Reports of bacterial predators eradicating biofilms or eliminating pathogens motivate a more systematic screening of biofilm-eliminating bacterial predators. Unfortunately, the analysis of the eradication process is demanding. In the present study, chip-calorimetry was applied to monitor the elimination of Pseudomonas sp. biofilms by Bdellovibrio bacteriovorus. The method uses metabolic heat as a real-time parameter for biofilm activity. The method is non-invasive, fast and convenient due to real-time data acquisition. In addition, heat-production data can reveal information about the energetics of the predator-prey interaction. The calorimetric results were validated by confocal laser scanning microscopy. The approach described may be useful for the screening of biofilm susceptibility to different predators. PMID:22509741

  10. Temperature Calibration for Optical Pyrometry in Containerless Systems Using Differential Scanning Calorimetry: Application to (-50)

    NASA Astrophysics Data System (ADS)

    Bendert, J. C.; Pueblo, C. E.; Veligati, S.; Mauro, N. A.; Kelton, K. F.

    2014-10-01

    Accurate and precise measurements of the temperature are important for controlling conditions in any experimental design. In containerless processing, such as in electrostatic levitation and electromagnetic levitation, the temperature is typically measured using optical pyrometers. These are generally calibrated to the sample of interest by measuring the temperatures of phase transitions. The presence of multiple heat signatures, differences in emissivity for different phases, and inconsistencies in published phase diagrams can make this difficult. In this manuscript, a method for using differential scanning calorimetry measurements for calibration is outlined and applied to four Cu-Zr alloys from the eutectic to the line compound. This technique is particularly valuable for systems in which accurate phase diagram information is unavailable or inaccurate.

  11. DNA heats up : Energetics of genome ejection from phage revealed by isothermal titration calorimetry

    E-print Network

    Meerim Jeembaeva; B. Jönsson; Martin Castelnovo; Alex Evilevitch

    2010-01-06

    Most bacteriophages are known to inject their double-stranded DNA into bacteria upon receptor binding in an essentially spontaneous way. This downhill thermodynamic process from the intact virion toward the empty viral capsid plus released DNA is made possible by the energy stored during active packaging of the genome into the capsid. Only indirect measurements of this energy have been available until now using either single-molecule or osmotic suppression techniques. In this paper, we describe for the first time the use of isothermal titration calorimetry to directly measure the heat released (or equivalently the enthalpy) during DNA ejection from phage lambda, triggered in solution by a solubilized receptor. Quantitative analyses of the results lead to the identification of thermodynamic determinants associated with DNA ejection. The values obtained were found to be consistent with those previously predicted by analytical models and numerical simulations. Moreover, the results confirm the role of DNA hydration in the energetics of genome confinement in viral capsids.

  12. Thermodynamic study of Cu2+ binding to the DAHK and GHK peptides by isothermal titration calorimetry (ITC) with the weaker competitor glycine.

    PubMed

    Trapaidze, Ana; Hureau, Christelle; Bal, Wojciech; Winterhalter, Mathias; Faller, Peter

    2012-01-01

    The peptides Asp-Ala-His-Lys (DAHK) and Gly-His-Lys (GHK) are naturally occurring Cu(II)-chelating motifs in human serum and cerebrospinal fluid. Here, the sensitive thermodynamic technique isothermal titration calorimetry was used to study the energetics of Cu(II) binding to DAHK and GHK peptides in the presence of the weaker ligand glycine as a competitor. DAHK and GHK bind Cu(II) predominantly in a 1:1 stoichiometry with conditional dissociation constants [i.e., at pH 7.4, in the absence of the competing chelators glycine and 2-(4-(2-hydroxyethyl)-1-piperazinyl)ethanesulfonic acid buffer] of 2.6 ± 0.4 × 10(-14) M and 7.0 ± 1.0 × 10(-14) M, respectively. Furthermore, the apparent ?H values were measured and the number of protons released upon Cu(II) binding was determined by performing experiments in different buffers. This allowed us to determine the conditional ?G, ?H, and ?S, i.e., corrected for the contributions of the weaker ligand glycine and the buffer at pH 7.4. We found that the entropic and enthalpic contributions to the Cu(II) binding to GHK and DAHK are distinct, with a enthalpic contribution for GHK. The thermodynamic parameters obtained correspond well to those in the literature obtained by other techniques, suggesting that the use of the weaker ligand glycine as a competitor in isothermal titration calorimetry provides accurate data for Cu(II) binding to high-affinity peptides, which cannot be accurately determined without the use of a competitor ligand. PMID:21898044

  13. Adsorption calorimetry during metal vapor deposition on single crystal surfaces: increased flux, reduced optical radiation, and real-time flux and reflectivity measurements.

    PubMed

    Sellers, Jason R V; James, Trevor E; Hemmingson, Stephanie L; Farmer, Jason A; Campbell, Charles T

    2013-12-01

    Thin films of metals and other materials are often grown by physical vapor deposition. To understand such processes, it is desirable to measure the adsorption energy of the deposited species as the film grows, especially when grown on single crystal substrates where the structure of the adsorbed species, evolving interface, and thin film are more homogeneous and well-defined in structure. Our group previously described in this journal an adsorption calorimeter capable of such measurements on single-crystal surfaces under the clean conditions of ultrahigh vacuum [J. T. Stuckless, N. A. Frei, and C. T. Campbell, Rev. Sci. Instrum. 69, 2427 (1998)]. Here we describe several improvements to that original design that allow for heat measurements with ~18-fold smaller standard deviation, greater absolute accuracy in energy calibration, and, most importantly, measurements of the adsorption of lower vapor-pressure materials which would have previously been impossible. These improvements are accomplished by: (1) using an electron beam evaporator instead of a Knudsen cell to generate the metal vapor at the source of the pulsed atomic beam, (2) changing the atomic beam design to decrease the relative amount of optical radiation that accompanies evaporation, (3) adding an off-axis quartz crystal microbalance for real-time measurement of the flux of the atomic beam during calorimetry experiments, and (4) adding capabilities for in situ relative diffuse optical reflectivity determinations (necessary for heat signal calibration). These improvements are not limited to adsorption calorimetry during metal deposition, but also could be applied to better study film growth of other elements and even molecular adsorbates. PMID:24387440

  14. Irreversible Denaturation of Maltodextrin Glucosidase Studied by Differential Scanning Calorimetry, Circular Dichroism, and Turbidity Measurements

    PubMed Central

    Goyal, Megha; Chaudhuri, Tapan K.; Kuwajima, Kunihiro

    2014-01-01

    Thermal denaturation of Escherichia coli maltodextrin glucosidase was studied by differential scanning calorimetry, circular dichroism (230 nm), and UV-absorption measurements (340 nm), which were respectively used to monitor heat absorption, conformational unfolding, and the production of solution turbidity. The denaturation was irreversible, and the thermal transition recorded at scan rates of 0.5–1.5 K/min was significantly scan-rate dependent, indicating that the thermal denaturation was kinetically controlled. The absence of a protein-concentration effect on the thermal transition indicated that the denaturation was rate-limited by a mono-molecular process. From the analysis of the calorimetric thermograms, a one-step irreversible model well represented the thermal denaturation of the protein. The calorimetrically observed thermal transitions showed excellent coincidence with the turbidity transitions monitored by UV-absorption as well as with the unfolding transitions monitored by circular dichroism. The thermal denaturation of the protein was thus rate-limited by conformational unfolding, which was followed by a rapid irreversible formation of aggregates that produced the solution turbidity. It is thus important to note that the absence of the protein-concentration effect on the irreversible thermal denaturation does not necessarily means the absence of protein aggregation itself. The turbidity measurements together with differential scanning calorimetry in the irreversible thermal denaturation of the protein provided a very effective approach for understanding the mechanisms of the irreversible denaturation. The Arrhenius-equation parameters obtained from analysis of the thermal denaturation were compared with those of other proteins that have been reported to show the one-step irreversible thermal denaturation. Maltodextrin glucosidase had sufficiently high kinetic stability with a half-life of 68 days at a physiological temperature (37°C). PMID:25548918

  15. An investigation of student thinking regarding calorimetry, entropy, and the second law of thermodynamics

    NASA Astrophysics Data System (ADS)

    Christensen, Warren Michael

    This thesis constitutes an investigation into student understanding of concepts in thermal physics in an introductory calculus-based university physics course. Nearly 90% of students enrolled in the course had previous exposure to thermodynamics concepts in chemistry and/or high-school physics courses. The two major thrusts of this work are (1) an exploration of student approaches to solving calorimetry problems involving two substances with differing specific heats, and (2) a careful probing of student ideas regarding certain aspects of entropy and the second law of thermodynamics. We present extensive free-response, interview, and multiple-choice data regarding students' ideas, collected both before and after instruction from a diverse set of course semesters and instructors. For topics in calorimetry, we found via interviews that students frequently get confused by, or tend to overlook, the detailed proportional reasoning or algebraic procedures that could lead to correct solutions. Instead, students often proceed with semi-intuitive reasoning that at times may be productive, but more often leads to inconsistencies and non-uniform conceptual understanding. Our investigation of student thinking regarding entropy suggests that prior to instruction, students have consistent and distinct patterns of incorrect or incomplete responses that often persist despite deliberate and focused efforts by the instructor. With modified instruction based on research-based materials, significant learning gains were observed on certain key concepts, e.g., that the entropy of the universe increases for all non-ideal processes. The methodology for our work is described, the data are discussed and analyzed, and a description is given of goals for future work in this area.

  16. Validation of a new mixing chamber system for breath-by-breath indirect calorimetry.

    PubMed

    Kim, Do-Yeon; Robergs, Robert Andrew

    2012-02-01

    Limited validation research exists for applications of breath-by-breath systems of expired gas analysis indirect calorimetry (EGAIC) during exercise. We developed improved hardware and software for breath-by-breath indirect calorimetry (NEW) and validated this system as well as a commercial system (COM) against 2 methods: (i) mechanical ventilation with known calibration gas, and (ii) human subjects testing for 5 min each at rest and cycle ergometer exercise at 100 and 175 W. Mechanical calibration consisted of medical grade and certified calibration gas ((4.95% CO(2), 12.01% O(2), balance N(2)), room air (20.95% O(2), 0.03% CO(2), balance N(2)), and 100% nitrogen), and an air flow turbine calibrated with a 3-L calibration syringe. Ventilation was mimicked manually using complete 3-L calibration syringe manouvers at a rate of 10·min(-1) from a Douglas bag reservoir of calibration gas. The testing of human subjects was completed in a counterbalanced sequence based on 5 repeated tests of all conditions for a single subject. Rest periods of 5 and 10 min followed the 100 and 175 W conditions, respectively. COM and NEW had similar accuracy when tested with known ventilation and gas fractions. However, during human subjects testing COM significantly under-measured carbon dioxide gas fractions, over-measured oxygen gas fractions and minute ventilation, and resulted in errors to each of oxygen uptake, carbon dioxide output, and respiratory exchange ratio. These discrepant findings reveal that controlled ventilation and gas fractions are insufficient to validate breath-by-breath, and perhaps even time-averaged, systems of EGAIC. The errors of the COM system reveal the need for concern over the validity of commercial systems of EGAIC. PMID:22300357

  17. Discolored1 (DSC1) is an ADP-Ribosylation Factor-GTPase Activating Protein Required to Maintain Differentiation of Maize Kernel Structures

    PubMed Central

    Takacs, Elizabeth M.; Suzuki, Masaharu; Scanlon, Michael J.

    2012-01-01

    The embryo and endosperm are the products of double fertilization and comprise the clonally distinct products of angiosperm seed development. Recessive mutations in the maize gene discolored1 (dsc1) condition inviable seed that are defective in both embryo and endosperm development. Here, detailed phenotypic analyses illustrate that discolored mutant kernels are able to establish, but fail to maintain, differentiated embryo, and endosperm structures. Development of the discolored mutant embryo and endosperm is normal albeit delayed, prior to the abortion and subsequent degeneration of all differentiated kernel structures. Using a genomic fragment that was previously isolated by transposon tagging, the full length dsc1 transcript is identified and shown to encode an ADP-ribosylation factor-GTPase activating protein (ARF-GAP) that co-localizes with the trans-Golgi network/early endosomes and the plasma membrane during transient expression assays in N. benthamiana leaves. DSC1 function during endomembrane trafficking and the maintenance of maize kernel differentiation is discussed. PMID:22666226

  18. Extensive studies on CeF 3 crystals, a good candidate for electromagnetic calorimetry at future accelerators

    Microsoft Academic Search

    Etiennette Auffray; S. Baccaro; T. Beckers; Ya Benhammou; A. N. Belsky; B. Borgia; D. Boutet; Rémi Chipaux; I. Dafinei; F. de Notaristefani; P. Depasse; C. Dujardin; H. El Mamouni; J. L. Faure; J. Fay; M. Goyot; S. K. Gupta; A. Gurtu; H. Hillemanns; B. Ille; T. Kirn; M. Lebeau; P. Lebrun; P. Lecoq; J. A. Mares; J. P. Martin; V. V. Mikhailin; B. Moine; J. Nelissen; M. Nikl; C. Pedrini; R. Raghavan; P. Sahuc; D. Schmitz; M. Schneegans; J. Schwenke; Stefaan Tavernier; V. Topa; A. N. Vasil'ev; M. Vivargent; J. P. Walder

    1996-01-01

    In the framework of its search for new heavy, fast and radiation hard scintillators for calorimetry at future colliders, the Crystal Clear Collaboration performed a systematic investigation of the properties and of the scintillation and radiation damage mechanisms of CeF3 monocrystals. Many samples of various dimensions up to 3 × 3 × 28 cm3 were produced by industry and characterised

  19. Kinetic properties of two Rhizopus exo-polygalacturonase enzymes hydrolyzing galacturonic acid oligomers using isothermal titration calorimetry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The kinetic characteristics of two Rhizopus oryzae exo-polygalacturonases acting on galacturonic acid oligomers (GalpA) were determined using isothermal titration calorimetry (ITC). RPG15 hydrolyzing (GalpA)2 demonstrated a Km of 55 uM and kcat of 10.3 s^-1^ while RPG16 was shown to have greater af...

  20. Thermodynamic stability and formation of aggregates of human immunoglobulin G characterised by differential scanning calorimetry and dynamic light scattering

    Microsoft Academic Search

    Karin Ahrer; Andrea Buchacher; Günter Iberer; Alois Jungbauer

    2006-01-01

    The final process step of polyclonal human immunoglobulin G is formulation with agents such as sugars, polyols, amino acid and salts. Often the most stable formulations were empirically identified. Physicochemical methods, such as differential scanning calorimetry and dynamic light scattering, provide a deeper insight on the biophysical properties of such a protein solution. The combination of these methods proved to

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  2. Thermodynamic characteristics of the acid-base equilibria of taurine in aqueous solutions, according to calorimetry data

    NASA Astrophysics Data System (ADS)

    Gridchin, S. N.; Shekhanov, R. F.; Pyreu, D. F.

    2015-02-01

    Enthalpies of the neutralization and protonation of taurine (HL) are measured by direct calorimetry at 298.15 K and ionic strengths of 0.3, 0.5, and 1.0 (KNO3). The standard thermodynamic characteristics of HL protolytic equilibria are calculated.

  3. Introduction of Differential Scanning Calorimetry in a General Chemistry Laboratory Course: Determination of Thermal Properties of Organic Hydrocarbons

    ERIC Educational Resources Information Center

    D'Amelia, Ronald; Franks, Thomas; Nirode, William F.

    2007-01-01

    In first-year general chemistry undergraduate courses, thermodynamics and thermal properties such as melting points and changes in enthalpy ([Delta]H) and entropy ([Delta]S) of phase changes are frequently discussed. Typically, classical calorimetric methods of analysis are used to determine [Delta]H of reactions. Differential scanning calorimetry

  4. Parallel nano-Differential Scanning Calorimetry: A New Device for Combinatorial Analysis of Complex nano-Scale Material Systems

    E-print Network

    1 Parallel nano-Differential Scanning Calorimetry: A New Device for Combinatorial Analysis of Complex nano-Scale Material Systems Patrick James McCluskey, and Joost J. Vlassak Division of Engineering is presented for the combinatorial analysis of complex nano-scale material systems. The parallel nano

  5. Sample Preparation Techniques for Determination of Fish Energy Density via Bomb Calorimetry: An Evaluation Using Largemouth Bass

    Microsoft Academic Search

    David C. Glover; Dennis R. DeVries; Russell A. Wright; Donald A. Davis

    2010-01-01

    We evaluated three homogenization and subsampling techniques for preparing fish tissue samples for bomb calorimetry to identify differences in efficiency for estimating fish energy density. We compared (1) drying the whole fish and homogenizing the dried fish tissue, (2) homogenization prior to drying and then drying the subsample of fish tissue, and (3) homogenization after autoclaving to soften the hard

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  7. DCal: A custom integrated circuit for calorimetry at the International Linear Collider

    SciTech Connect

    Hoff, James R.; Mekkaoui, Abderrazek; Yarema, Ray; /Fermilab; Drake, Gary; Repond, Jose; /Argonne

    2005-10-01

    A research and development collaboration has been started with the goal of producing a prototype hadron calorimeter section for the purpose of proving the Particle Flow Algorithm concept for the International Linear Collider. Given the unique requirements of a Particle Flow Algorithm calorimeter, custom readout electronics must be developed to service these detectors. This paper introduces the DCal or Digital Calorimetry Chip, a custom integrated circuit developed in a 0.25um CMOS process specifically for this International Linear Collider project. The DCal is capable of handling 64 channels, producing a 1-bit Digital-to-Analog conversion of the input (i.e. hit/no hit). It maintains a 24-bit timestamp and is capable of operating either in an externally triggered mode or in a self-triggered mode. Moreover, it is capable of operating either with or without a pipeline delay. Finally, in order to permit the testing of different calorimeter technologies, its analog front end is capable of servicing Particle Flow Algorithm calorimeters made from either Resistive Plate Chambers or Gaseous Electron Multipliers.

  8. AC Calorimetry and Thermophysical Properties of Bulk Glass-Forming Metallic Liquids

    NASA Technical Reports Server (NTRS)

    Johnson, William L.

    2000-01-01

    Thermo-physical properties of two bulk metallic glass forming alloys, Ti34Zr11Cu47Ni8 (VIT 101) and Zr57Nb5Ni12.6Al10CU15.4 (VIT 106), were investigated in the stable and undercooled melt. Our investigation focused on measurements of the specific heat in the stable and undercooled liquid using the method of AC modulation calorimetry. The VIT 106 exhibited a maximum undercooling of 140 K in free radiative cooling. Specific heat measurements could be performed in stable melt down to an undercooling of 80 K. Analysis of the specific heat data indicate an anomaly near the equilibrium liquidus temperature. This anomaly is also observed in y the temperature dependencies of the external relaxation time, the specific volume, and the surface tension; it is tentatively attributed to a phase separation in the liquid state. The VIT 101 specimen exhibited a small undercooling of about 50 K. Specific heat measurements were performed in the stable and undercooled melt. These various results will be combined with ground based work such as the measurement of T-T-T curves in the electrostatic levitator and low temperature viscosity and specific heat measurements for modeling the nucleation kinetics of these alloys.

  9. A novel optical calorimetry dosimetry approach applied to an HDR Brachytherapy source

    NASA Astrophysics Data System (ADS)

    Cavan, A.; Meyer, J.

    2013-06-01

    The technique of Digital Holographic Interferometry (DHI) is applied to the measurement of radiation absorbed dose distribution in water. An optical interferometer has been developed that captures the small variations in the refractive index of water due to the radiation induced temperature increase ?T. The absorbed dose D is then determined with high temporal and spatial resolution using the calorimetric relation D=c?T (where c is the specific heat capacity of water). The method is capable of time resolving 3D spatial calorimetry. As a proof-of-principle of the approach, a prototype DHI dosimeter was applied to the measurement of absorbed dose from a High Dose Rate (HDR) Brachytherapy source. Initial results are in agreement with modelled doses from the Brachyvision treatment planning system, demonstrating the viability of the system for high dose rate applications. Future work will focus on applying corrections for heat diffusion and geometric effects. The method has potential to contribute to the dosimetry of diverse high dose rate applications which require high spatial resolution such as microbeam radiotherapy (MRT) or small field proton beam dosimetry but may potentially also be useful for interface dosimetry.

  10. Critical appraisal and further development of the methodology for open circuit calorimetry in neonates.

    PubMed

    Handley, J C; Spencer, S A; Rakowski, S; Rolfe, P

    1991-10-01

    A non-invasive technique for open circuit calorimetry based on a Vickers 79 incubator as the gas collection chamber was developed and evaluated. The technique, which involved drawing air from the incubator hood at 11 1/min for gas analysis, did not have a significant cooling effect on the infant and the noise levels within the incubator did not exceed current safety standards. A new technique for checking the calibration of the whole system was developed as the traditional alcohol burn method proved unsatisfactory. Either pure oxygen or carbon dioxide were fed into the incubator hood at controlled physiological rates using a calibrated throttling valve. Over a number of calibration checks the mean error of the system proved to be +/- 4.3% for oxygen and +/- 4.45% for carbon dioxide. Less than a fifth of this error was attributable to the pump and flow meter. When oxygen is introduced to the system at a constant physiological rate it takes 30 min for a plateau to be reached. Therefore it is recommended that this system is used when readings are to be taken in a steady state situation or data is to be cumulated over a long period of time such as in an energy balance study. A run in period of 30 min before collecting data is essential. It is recommended that a calibration check is performed before each study. PMID:1773743

  11. Single-strand DNA translation initiation step analyzed by Isothermal Titration Calorimetry

    SciTech Connect

    Damian, Luminita, E-mail: luminitadamian@microcal.eu.com [CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), 205 route de Narbonne, F-31077 Toulouse (France) [CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), 205 route de Narbonne, F-31077 Toulouse (France); Universite de Toulouse, UPS, IPBS, F-31077 Toulouse (France); IUB, School of Engineering and Science, D-28727 Bremen (Germany); Marty-Detraves, Claire, E-mail: claire.detraves@free.fr [CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), 205 route de Narbonne, F-31077 Toulouse (France) [CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), 205 route de Narbonne, F-31077 Toulouse (France); Universite de Toulouse, UPS, IPBS, F-31077 Toulouse (France); Winterhalter, Mathias [IUB, School of Engineering and Science, D-28727 Bremen (Germany)] [IUB, School of Engineering and Science, D-28727 Bremen (Germany); Fournier, Didier, E-mail: Didier.Fournier@ipbs.fr [CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), 205 route de Narbonne, F-31077 Toulouse (France) [CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), 205 route de Narbonne, F-31077 Toulouse (France); Universite de Toulouse, UPS, IPBS, F-31077 Toulouse (France); Paquereau, Laurent, E-mail: Laurent.Paquereau@ipbs.fr [CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), 205 route de Narbonne, F-31077 Toulouse (France) [CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), 205 route de Narbonne, F-31077 Toulouse (France); Universite de Toulouse, UPS, IPBS, F-31077 Toulouse (France)

    2009-07-31

    Is single-strand DNA translatable? Since the 60s, the question still remains whether or not DNA could be directly translated into protein. Some discrepancies in the results were reported about functional translation of single-strand DNA but all results converged on a similar behavior of RNA and ssDNA in the initiation step. Isothermal Titration Calorimetry method was used to determine thermodynamic constants of interaction between single-strand DNA and S30 extract of Escherichia coli. Our results showed that the binding was not affected by the nature of the template tested and the dissociation constants were in the same range when ssDNA (K{sub d} = 3.62 {+-} 2.1 x 10{sup -8} M) or the RNA corresponding sequence (K{sub d} = 2.7 {+-} 0.82 x 10{sup -8} M) bearing SD/ATG sequences were used. The binding specificity was confirmed by antibiotic interferences which block the initiation complex formation. These results suggest that the limiting step in translation of ssDNA is the elongation process.

  12. Interaction of human serum albumin with short polyelectrolytes: a study by calorimetry and computer simulations.

    PubMed

    Yu, Shun; Xu, Xiao; Yigit, Cemil; van der Giet, Markus; Zidek, Walter; Jankowski, Joachim; Dzubiella, Joachim; Ballauff, Matthias

    2015-06-01

    We present a comprehensive study of the interaction of human serum albumin (HSA) with poly(acrylic acid) (PAA; number average degree of polymerization: 25) in aqueous solution. The interaction of HSA with PAA is studied in dilute solution as a function of the concentration of added salt (20-100 mM) and temperature (25-37 °C). Isothermal titration calorimetry (ITC) is used to analyze the interaction and to determine the binding constant and related thermodynamic data. It is found that only one PAA chain is bound per HSA molecule. The free energy of binding ?Gb increases with temperature significantly. ?Gb decreases with increasing salt concentration and is dominated by entropic contributions due to the release of bound counterions. Coarse-grained Langevin computer simulations treating the counterions in an explicit manner are used to study the process of binding in detail. These simulations demonstrate that the PAA chains are bound in the Sudlow II site of HSA. Moreover, ?Gb is calculated from the simulations and found to be in very good agreement with the measured data. The simulations demonstrate clearly that the driving force of binding is the release of counterions in full agreement with the ITC-data. PMID:25959568

  13. Prospects for true calorimetry on Kerr black holes in core-collapse supernovae and mergers

    SciTech Connect

    Putten, Maurice H. P. M. van [Department of Physics, Korea Institute for Advanced Study, 87 Hoegiru, Dongdaemun-Gu, Seoul 130-722 (Korea, Republic of); Kanda, Nobuyuki [Department of Physics, Graduate School of Science, Osaka City University, Osaka 558-8585 (Japan); Tagoshi, Hideyuki [Department of Earth and Space Science, Graduate School of Science, Osaka City University, Osaka 558-8585 (Japan); Tatsumi, Daisuke; Masa-Katsu, Fujimoto [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Della Valle, Massimo [Istituto Nazionale di Astrofisica-Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, I-80131 Napoli (Italy); International Center for Relativistic Astrophysics, Piazzale della Repubblica 2, I-65122, Pescara (Italy)

    2011-02-15

    Observational evidence for black hole spin down has been found in the normalized light curves of long gamma-ray bursts in the BATSE catalog. Over the duration T{sub 90} of the burst, matter swept up by the central black hole is susceptible to nonaxisymmetries, producing gravitational radiation with a negative chirp. A time-sliced matched filtering method is introduced to capture phase coherence on intermediate time scales, {tau}, here tested by the injection of templates into experimental strain noise, h{sub n}(t). For TAMA 300, h{sub n}(f){approx_equal}10{sup -21} Hz{sup -1/2} at f=1 kHz gives a sensitivity distance for a reasonably accurate extraction of the trajectory in the time-frequency domain of about D{approx_equal}0.07-0.10 Mpc for the spin down of black holes of mass M=10-12M{sub {center_dot}} with {tau}=1 s. Extrapolation to advanced detectors implies D{approx_equal}35-50 Mpc for h{sub n}(f){approx_equal}2x10{sup -24} Hz{sup -1/2} around 1 kHz, which will open a new window to rigorous calorimetry on Kerr black holes.

  14. Application of Differential Scanning Calorimetry to Evaluate Thermal Properties and Study of Microstructure of Biodegradable Films

    NASA Astrophysics Data System (ADS)

    Aguilar-Méndez, M. A.; Martin-Martínez, E. San; Ortega-Arroyo, L.; Cruz-Orea, A.

    2010-03-01

    The glass transition temperature ( T g) and melting temperature ( T m) of gelatin-starch films were determined using differential scanning calorimetry. Also, the microstructure was observed using scanning electron microscopy (SEM) and the crystalline structure by means of X-ray diffraction (XRD). The effect of starch and glycerol concentrations in films on the thermal properties was evaluated through response surface methodology (RSM). The highest values of T m were obtained at starch concentration intervals of (0.26 to 0.54) %w/w and glycerol concentrations lower than 0.5 (%w/w). On the other hand, the T g values diminished as the glycerol concentration increased. Mathematical models for both transitions were fitted to the experimental data. The micrographs obtained by SEM show the influence of glycerol in the microstructure of the films, being more “gummy” as the content of the plasticizer increased. The XRD patterns of the films demonstrate the existence of some pseudo-crystalline regions in the biodegradable materials.

  15. A Universal Method for Fishing Target Proteins from Mixtures of Biomolecules using Isothermal Titration Calorimetry

    SciTech Connect

    Zhou, X.; Sun, Q; Kini, R; Sivaraman, J

    2008-01-01

    The most challenging tasks in biology include the identification of (1) the orphan receptor for a ligand, (2) the ligand for an orphan receptor protein, and (3) the target protein(s) for a given drug or a lead compound that are critical for the pharmacological or side effects. At present, several approaches are available, including cell- or animal-based assays, affinity labeling, solid-phase binding assays, surface plasmon resonance, and nuclear magnetic resonance. Most of these techniques are not easy to apply when the target protein is unknown and the compound is not amenable to labeling, chemical modification, or immobilization. Here we demonstrate a new universal method for fishing orphan target proteins from a complex mixture of biomolecules using isothermal titration calorimetry (ITC) as a tracking tool. We took snake venom, a crude mixture of several hundred proteins/peptides, as a model to demonstrate our proposed ITC method in tracking the isolation and purification of two distinct target proteins, a major component and a minor component. Identities of fished out target proteins were confirmed by amino acid sequencing and inhibition assays. This method has the potential to make a significant advancement in the area of identifying orphan target proteins and inhibitor screening in drug discovery and characterization.

  16. Accurate temperature model for absorptance determination of optical components with laser calorimetry

    SciTech Connect

    Wang Yanru; Li Bincheng

    2011-03-20

    In the international standard (International Organization for Standardization 11551) for measuring the absorptance of optical components (i.e., laser calorimetry), the absorptance is obtained by fitting the temporal behavior of laser irradiation-induced temperature rise to a homogeneous temperature model in which the infinite thermal conductivity of the sample is assumed. In this paper, an accurate temperature model, in which both the finite thermal conductivity and size of the sample are taken into account, is developed to fit the experimental temperature data for a more precise determination of the absorptance. The difference and repeatability of the results fitted with the two theoretical models for the same experimental data are compared. The optimum detection position when the homogeneous model is employed in the data-fitting procedure is also analyzed with the accurate temperature model. The results show that the optimum detection location optimized for a wide thermal conductivity range of 0.2-50W/m{center_dot}K moves toward the center of the sample as the sample thickness increases and deviates from the center as the radius and irradiation time increase. However, if the detection position is optimized for an individual sample with known sample size and thermal conductivity by applying the accurate temperature model, the influence of the finite thermal conductivity and sample size on the absorptance determination can be fully compensated for by fitting the temperature data recorded at the optimum detection position to the homogeneous temperature model.

  17. Real-Time Monitoring of Membrane-Protein Reconstitution by Isothermal Titration Calorimetry

    PubMed Central

    2013-01-01

    Phase diagrams offer a wealth of thermodynamic information on aqueous mixtures of bilayer-forming lipids and micelle-forming detergents, providing a straightforward means of monitoring and adjusting the supramolecular state of such systems. However, equilibrium phase diagrams are of very limited use for the reconstitution of membrane proteins because of the occurrence of irreversible, unproductive processes such as aggregation and precipitation that compete with productive reconstitution. Here, we exemplify this by dissecting the effects of the K+ channel KcsA on the process of bilayer self-assembly in a mixture of Escherichia coli polar lipid extract and the nonionic detergent octyl-?-d-glucopyranoside. Even at starting concentrations in the low micromolar range, KcsA has a tremendous impact on the supramolecular organization of the system, shifting the critical lipid/detergent ratios at the onset and completion of vesicle formation by more than 2-fold. Thus, equilibrium phase diagrams obtained for protein-free lipid/detergent mixtures would be misleading when used to guide the reconstitution process. To address this issue, we demonstrate that, even under such nonequilibrium conditions, high-sensitivity isothermal titration calorimetry can be exploited to monitor the progress of membrane-protein reconstitution in real time, in a noninvasive manner, and at high resolution to yield functional proteoliposomes with a narrow size distribution for further downstream applications. PMID:24354292

  18. Interaction of oridonin with human serum albumin by isothermal titration calorimetry and spectroscopic techniques.

    PubMed

    Li, Xiangrong; Yang, Zhenhua

    2015-05-01

    Oridonin has been traditionally and widely used for treatment of various human diseases due to its uniquely biological, pharmacological and physiological functions. In this study, the interaction between oridonin and human serum albumin (HSA) was investigated using isothermal titration calorimetry (ITC), in combination with fluorescence spectroscopy and UV-vis absorption spectroscopy. We found that the hydrogen bond and van der Waals force are the major binding forces in the binding of oridonin to HSA. The binding of oridonin to HSA is driven by favorable enthalpy and unfavorable entropy. Oridonin can quench the fluorescence of HSA through a static quenching mechanism. The binding constant between oridonin and HSA is moderate and the equilibrium fraction of unbound oridonin f(u) > 60%. Binding site I is found to be the primary binding site for oridonin. Additionally, oridonin may induce conformational changes of HSA and affect its biological function as the carrier protein. The results of the current study suggest that oridonin can be stored and transported from the circulatory system to reach its target organ to provide its therapeutic effects. But its side-effect in the clinics cannot be overlook. The study provides an accurate and full basic data for clarifying the binding mechanism of oridonin with HSA and is helpful for understanding its effect on protein function during the blood transportation process and its biological activity in vivo. PMID:25816984

  19. Interaction of Human Serum Albumin with short Polyelectrolytes: A study by Calorimetry and Computer Simulation

    E-print Network

    Shun Yu; Xiao Xu; Cemil Yigit; Markus van der Giet; Walter Zidek; Joachim Jankowski; Joachim Dzubiella; Matthias Ballauff

    2015-07-10

    We present a comprehensive study of the interaction of human serum albumin (HSA) with poly(acrylic acid) (PAA; number average degree of polymerization: 25) in aqueous solution. The interaction of HSA with PAA is studied in dilute solution as the function of the concentration of added salt (20 - 100 mM) and temperature (25 - 37$^{\\circ}$C). Isothermal titration calorimetry (ITC) is used to analyze the interaction and to determine the binding constant and related thermodynamic data. It is found that only one PAA chain is bound per HSA molecule. The free energy of binding $\\Delta G_b$ increases with temperature significantly. $\\Delta G_b$ decreases with increasing salt concentration and is dominated by entropic contributions due to the release of bound counterions. Coarse-grained Langevin computer simulations treating the counterions in an explicit manner are used study the process of binding in detail. These simulations demonstrate that the PAA chains are bound in the Sudlow II site of the HSA. Moreover, $\\Delta G_b$ is calculated from the simulations and found to be in very good agreement with the measured data. The simulations demonstrate clearly that the driving force of binding is the release of counterions in full agreement with the ITC-data.

  20. Interaction of human serum albumin with short polyelectrolytes: a study by calorimetry and computer simulations

    NASA Astrophysics Data System (ADS)

    Yu, Shun; Xu, Xiao; Yigit, Cemil; van der Giet, Markus; Zidek, Walter; Jankowski, Joachim; Dzubiella, Joachim; Ballauff, Matthias

    We present a comprehensive study of the interaction of human serum albumin (HSA) with poly(acrylic acid) (PAA; number average degree of polymerization: 25) in aqueous solution. The interaction of HSA with PAA is studied in dilute solution as the function of the concentration of added salt (20 - 100 mM) and temperature (25 - 37$^{\\circ}$C). Isothermal titration calorimetry (ITC) is used to analyze the interaction and to determine the binding constant and related thermodynamic data. It is found that only one PAA chain is bound per HSA molecule. The free energy of binding $\\Delta G_b$ increases with temperature significantly. $\\Delta G_b$ decreases with increasing salt concentration and is dominated by entropic contributions due to the release of bound counterions. Coarse-grained Langevin computer simulations treating the counterions in an explicit manner are used study the process of binding in detail. These simulations demonstrate that the PAA chains are bound in the Sudlow II site of the HSA. Moreover, $\\Delta G_b$ is calculated from the simulations and found to be in very good agreement with the measured data. The simulations demonstrate clearly that the driving force of binding is the release of counterions in full agreement with the ITC-data.

  1. A universal method for fishing target proteins from mixtures of biomolecules using isothermal titration calorimetry

    PubMed Central

    Zhou, Xingding; Sun, Qingxiang; Kini, R. Manjunatha; Sivaraman, J.

    2008-01-01

    The most challenging tasks in biology include the identification of (1) the orphan receptor for a ligand, (2) the ligand for an orphan receptor protein, and (3) the target protein(s) for a given drug or a lead compound that are critical for the pharmacological or side effects. At present, several approaches are available, including cell- or animal-based assays, affinity labeling, solid-phase binding assays, surface plasmon resonance, and nuclear magnetic resonance. Most of these techniques are not easy to apply when the target protein is unknown and the compound is not amenable to labeling, chemical modification, or immobilization. Here we demonstrate a new universal method for fishing orphan target proteins from a complex mixture of biomolecules using isothermal titration calorimetry (ITC) as a tracking tool. We took snake venom, a crude mixture of several hundred proteins/peptides, as a model to demonstrate our proposed ITC method in tracking the isolation and purification of two distinct target proteins, a major component and a minor component. Identities of fished out target proteins were confirmed by amino acid sequencing and inhibition assays. This method has the potential to make a significant advancement in the area of identifying orphan target proteins and inhibitor screening in drug discovery and characterization. PMID:18621915

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

    NASA Astrophysics Data System (ADS)

    Migda?-Mikuli, Anna; Skoczylas, ?ukasz

    2008-12-01

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

  3. Thermodynamic Profiling of Peptide Membrane Interactions by Isothermal Titration Calorimetry: A Search for Pores and Micelles

    PubMed Central

    Henriksen, J.R.; Andresen, T.L.

    2011-01-01

    Antimicrobial peptides are known to interact strongly with negatively charged lipid membranes, initially by peripheral insertion of the peptide into the bilayer, which for some antimicrobial peptides will be followed by pore formation, and successive solubilization of the membranes resulting in mixed peptide-lipid micelles. We have investigated the mode of action of the antimicrobial peptide mastoparan-X using isothermal titration calorimetry (ITC) and cryo-transmission electron microscopy (cryo-TEM). The results show that mastoparan-X induces a range of structural transitions of POPC/POPG (3:1) lipid membranes at different peptide/lipid ratios. It has been established that ITC can be used as a fast method for localizing membrane transitions and when combined with DLS and cryo-TEM can elucidate structural changes, including the threshold for pore formation and micellation. Cryo-TEM was employed to confirm the structural changes associated with the thermodynamic transitions found by ITC. The pore-formation process has furthermore been investigated in detail and the thermodynamic parameters of pore formation have been characterized using a system-specific temperature where the enthalpy of peptide partitioning becomes zero (Tzero). This allows for an exclusive study of the pore-formation process. The use of ITC to find Tzero allows for characterization of the thermodynamic parameters of secondary processes on lipid membranes. PMID:21723819

  4. A yeast transcription factor bypassing the requirement for SBF and DSC1/MBF in budding yeast has homology to bacterial signal transduction proteins.

    PubMed Central

    Morgan, B A; Bouquin, N; Merrill, G F; Johnston, L H

    1995-01-01

    The transcription factors SBF and DSC1/MBF bind SCB and MCB promoter elements, respectively, and are essential for the cell cycle progression of Saccharomyces cerevisiae through the control of G1 cyclin gene expression. We isolated a gene (BRY1; Bacterial Response regulator in Yeast) able to activate either MCB or SCB promoter elements on a reporter plasmid which, when overexpressed, can bypass the normally essential requirement for SBF and DSC1/MBF by the stimulation of CLN1 and CLN2 expression. In the case of CLN2 at least, this expression depends upon the MCB and SCB promoter elements. In wild-type yeast, the disruption of BRY1 has no apparent phenotype, but under conditions where the activities of SBF and DSC1/MBF are reduced, BRY1 becomes essential. Our data imply the existence of a third pathway affecting cyclin expression. BRY1 is the same gene as SKN7 which has significant sequence homology to the receiver domains found in response regulator proteins from the bacterial two-component signal transduction pathways. SKN7 is thought to affect cell wall structure, and when highly overexpressed we find that BRY1/SKN7 is lethal perhaps because of perturbations in cell wall biosynthesis. The lethality is partially rescued by genes from the protein kinase C pathway, but genetic data imply that BRY1/SKN7 and protein kinase C are not in the same pathway. Our results suggest that Bry1/Skn7 can influence the expression of MCB- and SCB-driven gene expression in budding yeast, perhaps including genes involved in cell wall metabolism, via a two-component signal transduction pathway which activates Bry1/Skn7 in response to an unidentified signal. Images PMID:8521825

  5. Measurement of water transport during freezing in mammalian liver tissue: Part II--The use of differential scanning calorimetry.

    PubMed

    Devireddy, R V; Bischof, J C

    1998-10-01

    There is currently a need for experimental techniques to assay the biophysical response (water transport or intracellular ice formation, IIF) during freezing in the cells of whole tissue slices. These data are important in understanding and optimizing biomedical applications of freezing, particularly in cryosurgery. This study presents a new technique using a Differential Scanning Calorimeter (DSC) to obtain dynamic and quantitative water transport data in whole tissue slices during freezing. Sprague-Dawley rat liver tissue was chosen as our model system. The DSC was used to monitor quantitatively the heat released by water transported from the unfrozen cell cytoplasm to the partially frozen vascular/extracellular space at 5 degrees C/min. This technique was previously described for use in a single cell suspension system (Devireddy, et al. 1998). A model of water transport was fit to the DSC data using a nonlinear regression curve-fitting technique, which assumes that the rat liver tissue behaves as a two-compartment Krogh cylinder model. The biophysical parameters of water transport for rat liver tissue at 5 degrees C/min were obtained as Lpg = 3.16 x 10(-13) m3/Ns (1.9 microns/min-atm), ELp = 265 kJ/mole (63.4 kcal/mole), respectively. These results compare favorably to water transport parameters in whole liver tissue reported in the first part of this study obtained using a freeze substitution (FS) microscopy technique (Pazhayannur and Bischof, 1997). The DSC technique is shown to be a fast, quantitative, and reproducible technique to measure dynamic water transport in tissue systems. However, there are several limitations to the DSC technique: (a) a priori knowledge that the biophysical response is in fact water transport, (b) the technique cannot be used due to machine limitations at cooling rates greater than 40 degrees C/min, and (c) the tissue geometric dimensions (the Krogh model dimensions) and the osmotically inactive cell volumes Vb, must be determined by low-temperature microscopy techniques. PMID:10412432

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

    NASA Astrophysics Data System (ADS)

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

    2002-02-01

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

  7. Effect of segmented poly(ester-siloxane)urethanes compositional parameters on differential scanning calorimetry and dynamic-mechanical measurements

    Microsoft Academic Search

    S Ioan; G Grigorescu; A Stanciu

    2002-01-01

    Segmented poly(ester-siloxane)urethanes containing hard and soft segments were prepared by melt polyaddition using a multistep procedure. The soft segments based on poly(ethylene glycol adipate)diol as ester sequences and ?,?-poly(dimethylsiloxane)diol as silicone sequences were synthesized. The hard segments were based on aromatic or aliphatic diisocyanates and butanediol was used as chain extender. These polyurethane materials were analysed by differential scanning calorimetry

  8. Comparative results of autogenous ignition temperature measurements by ASTM G 72 and pressurized scanning calorimetry in gaseous oxygen

    NASA Technical Reports Server (NTRS)

    Bryan, C. J.; Lowrie, R.

    1986-01-01

    The autogenous ignition temperature of four materials was determined by ASTM (G 72) and pressurized differential scanning calorimetry at 0.68-, 3.4-, and 6.8-MPa oxygen pressure. All four materials were found to ignite at lower temperatures in the ASTM method. The four materials evaluated in this program were Neoprene, Vespel SP-21, Fluorel E-2160, and nylon 6/6.

  9. Monitoring the early-age hydration of self-compacting concrete using ultrasonic p-wave transmission and isothermal calorimetry

    Microsoft Academic Search

    Bram DesmetKelly; Kelly Chrysanthe Atitung; Miguel Angel Abril Sanchez; John Vantomme; Dimitri Feys; Nicolas Robeyst; Katrien Audenaert; Geert De Schutter; Veerle Boel; Gert Heirman; Özlem Cizer; Lucie Vandewalle; Dionys Van Gemert

    The early-age hydration (?48 h) of a series of self-compacting concretes and corresponding mortars and one traditionally vibrated\\u000a concrete and mortar is monitored in a continuous way using ultrasonic testing and isothermal calorimetry. The mixtures differ\\u000a in type of mineral addition, superplasticizer, cement, cement-to-powder ratio and water-to-powder ratio. The influence of\\u000a these different mixture compositions on the kinetics of the hydration

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

    Microsoft Academic Search

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

    2003-01-01

    The thermal phase transition behavior of water incorporated in crosslinked polystyrene–divinylbenzene copolymer (PS–DVB) gel packings for liquid chromatography was investigated by differential scanning calorimetry. Free or bulk water, freezable bound or intermediate water, and nonfreezing water were observed for TSKgel Styrene-250 samples, while only free water and nonfreezing water were observed for TSKgel Styrene-60 samples. Freezable bound water and nonfreezing

  11. Measurement of the background in the NEMO 3 double beta decay experiment

    E-print Network

    NEMO Collaboration; J. Argyriades; R. Arnold; C. Augier; J. Baker; A. S. Barabash; M. Bongrand; G. Broudin-Bay; V. B. Brudanin; A. J. Caffrey; A. Chapon; E. Chauveau; Z. Daraktchieva; D. Durand; V. G. Egorov; N. Fatemi-Ghomi; R. Flack; A. Freshville; B. Guillon; Ph. Hubert; S. Jullian; M. Kauer; S. King; O. I. Kochetov; S. I. Konovalov; V. E. Kovalenko; D. Lalanne; K. Lang; Y. Lemi`ere; G. Lutter; F. Mamedov; Ch. Marquet; J. Martin-Albo; F. Mauger; A. Nachab; I. Nasteva; I. B. Nemchenok; F. Nova; P. Novella; H. Ohsumi; R. B. Pahlka; F. Perrot; F. Piquemal; J. L. Reyss; J. S. Ricol; R. Saakyan; X. Sarazin; L. Simard; Yu. A. Shitov; A. A. Smolnikov; S. Snow; S. S"oldner-Rembold; I. Stekl; C. S. Sutton; G. Szklarz; J. Thomas; V. V. Timkin; V. I. Tretyak; Vl. I. Tretyak; V. I. Umatov; L. V'ala; I. A. Vanyushin; V. A. Vasiliev; V. Vorobel; Ts. Vylov

    2009-03-12

    In the double beta decay experiment NEMO~3 a precise knowledge of the background in the signal region is of outstanding importance. This article presents the methods used in NEMO~3 to evaluate the backgrounds resulting from most if not all possible origins. It also illustrates the power of the combined tracking-calorimetry technique used in the experiment.

  12. Specific Heat of Powdered Buckminsterfullerene from 20 K to 300 K by Continuous-Cooling Calorimetry

    NASA Astrophysics Data System (ADS)

    Li, Hui

    A heat capacity study of polycrystalline C _{60} by continuous-cooling calorimetry is presented. Details of the continuous-cooling method and the experimental setup are described. The method was tested by measuring the heat capacity of solid copper sample, a powdered graphite sample and a solid glassy carbon sample and comparing to known results. Heat capacity measurements of loose powdered C_{60} in a He-filled envelope and of a pressed pellet of C _{60} powder mixed with copper powder were made between 20 K and 300 K. Evidence of a first order phase transition in solid C_{60} is shown clearly by the large heat capacity anomaly at T _{rm c} = 259 K, but no clear evidence emerged in this study of the glass transition at 90 K seen by other workers. By selecting baselines under the peak from 120 K to 300 K, the enthalpy and the entropy of the transition are estimated as 8.5 +/- 0.4 kJ/mol and 36.2 +/- 1.9 J/K-mol for the loose powder sample, and 7.6 +/- 0.6 kJ/mol and 33.7 +/- 3.1 J/K-mol for the pellet sample. The contributions to the heat capacity of C_{60} arising from vibrations, librations and rotations are calculated using standard models and experimental information. For the pellet sample in the regime above T_ {rm c} there is a deficit of about 20% between these contributions and the measured heat capacity. The presence of a substantial number of defects was confirmed by broadened and washed out Bragg peaks in an x-ray diffraction pattern of this pellet sample. With the aid of a simple phenomenological model, the contribution of the annealing of these defects to the heat capacity is calculated and used to explain the heat capacity deficit.

  13. Digital holographic interferometry: A novel optical calorimetry technique for radiation dosimetry

    SciTech Connect

    Cavan, Alicia, E-mail: alicia.cavan@cdhb.health.nz [Department of Physics and Astronomy, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand and Christchurch Hospital, Private Bag 4710, Christchurch 8140 (New Zealand)] [Department of Physics and Astronomy, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand and Christchurch Hospital, Private Bag 4710, Christchurch 8140 (New Zealand); Meyer, Juergen, E-mail: juergen@uw.edu [Department of Radiation Oncology, University of Washington, 1959 Northeast Pacific Street, Box 356043, Seattle, Washington 98195 (United States)] [Department of Radiation Oncology, University of Washington, 1959 Northeast Pacific Street, Box 356043, Seattle, Washington 98195 (United States)

    2014-02-15

    Purpose: To develop and demonstrate the proof-of-principle of a novel optical calorimetry method to determine radiation absorbed dose in a transparent medium. Methods: The calorimetric property of water is measured during irradiation by means of an interferometer, which detects temperature-induced changes in the refractive index that can be mathematically related to absorbed dose. The proposed method uses a technique called digital holographic interferometry (DHI), which comprises an optical laser interferometer setup and consecutive physical reconstruction of the recorded wave fronts by means of the Fresnel transform. This paper describes the conceptual framework and provides the mathematical basis for DHI dosimetry. Dose distributions from a high dose rate Brachytherapy source were measured by a prototype optical setup to demonstrate the feasibility of the approach. Results: The developed DHI dosimeter successfully determined absorbed dose distributions in water in the region adjacent to a high dose rate Brachytherapy source. A temperature change of 0.0381 K across a distance of 6.8 mm near the source was measured, corresponding to a dose of 159.3 Gy. The standard deviation in a typical measurement set was ±3.45 Gy (corresponding to an uncertainty in the temperature value of ±8.3 × 10{sup ?4} K). The relative dose fall off was in agreement with treatment planning system modeled data. Conclusions: First results with a prototype optical setup and a Brachytherapy source demonstrate the proof-of-principle of the approach. The prototype achieves high spatial resolution of approximately 3 × 10{sup ?5} m. The general approach is fundamentally independent of the radiation type and energy. The sensitivity range determined indicates that the method is predominantly suitable for high dose rate applications. Further work is required to determine absolute dose in all three dimensions.

  14. Thermophysical properties of metallic systems determined by pulse-heating calorimetry

    NASA Astrophysics Data System (ADS)

    Falcon, Douglas Stewart

    The temperature dependence of the isobaric specific heat (Cp) and electrical resistivity (rho) were simultaneously determined for several metallic alloy systems using a pulse-heating calorimeter (PHC). Data were obtained at relatively high heating rates (typically between 25 and 350 K/s) in various temperature ranges from 300 to 1500 K. The theoretical basis of operation and some advantages and limitations of the PHC were discussed. The kinetics of the disorder/order (SRO (alpha)/LRO (beta)) transformation in Ni4Mo was investigated, and DeltaGalpha?beta was determined between 300 and 1400 K. For Ni4Mo, a TTT start-curve was determined for the alpha to beta transformation, along with LRO parameter data between 923 and 1113 K. For Fe-30 at% Al and Fe-43 at% Al binary alloys, data were contrasted between step-cooled and naturally-cooled initial conditions. Vacancy and triple-defect concentrations, and triple-defect formation enthalpy were determined for the Fe-43 at% Al alloy. In the Fe-30 at% Al alloy, the DO3 to B2 phase transformation was detected. The allotropic (Tt) and magnetic (Curie) transformation temperatures were determined for pure Co. Isothermal annealing below Tt had the effect of raising Tt on a subsequent pulse-heating test for pure Co. In the Co-Cr-based superalloy ULTIMET(TM), the Cp data obtained by DSC exhibit deviation from smooth behavior between 825 and 975 K, in contrast to data obtained with the PHC. In the Ni-Cr-based alloy Hastelloy(TM) G-30, data indicate a structural change between approximately 875 and 1100 K, the cause of which is unexplained. For Hastelloy(TM) G-30, p-time data were obtained isothermally between 775 and 1475 K. The glass transition and crystallization behavior of a Zr52.5Ti5Cu17.9Ni14.6 Al10 bulk amorphous alloy (BAA) were studied. Cp and rho data were obtained in both the as-cast (amorphous) and crystalline initial conditions. The melting, glass transition, crystallization, and reduced glass transition temperatures were determined. Features of rho-temperature data obtained at higher heating rates are interpreted as being due to some type of (unidentified) precursor structure that formed prior to crystallization. Microstructure (SEM) and microhardness data were obtained subsequent to pulse-heating and cooling on one specimen.

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

    NASA Astrophysics Data System (ADS)

    Migda?-Mikuli, Anna; Szostak, El?bieta

    2005-04-01

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

  16. Temperature-modulated calorimetry of the frequency dependence of the glass transition of poly(ethylene terephthalate) and ....

    SciTech Connect

    Wunderlich, B.; Okazaki, I. [Oak Ridge National Lab., TN (United States)] [Tennessee Univ., Knoxville, TN (United States). Dept. of Chemistry

    1997-03-01

    Temperature-modulated differential scanning calorimetry, TMDSC, is new technique that permits to measure the apparent heat capacity vs modulation frequency. The method is briefly described and a quasi- isothermal measurement method is used to derive the kinetic parameters for PET and PS. A first-order kinetics expression was used to describe the approach to equilibrium and point out the limits caused by asymmetry and cooperativity of the kinetics. Use of a complex description of heat capacity and entropy is discussed. Activation energies vary from 75 to 350 kJ/mol, dependent on thermal pretreatment and the preexponential factor is correlated with the activation energy.

  17. Studies on Cure Kinetics of Poly(phenylene ether)\\/Epoxy Resin System Using an Advanced Iso-Conversional Method

    Microsoft Academic Search

    Xiufang Wen; Wei Wang; Zhi-Qi Cai; Pihui Pi; Dafeng Zheng; Xin Dong; Jiang Cheng; Zhuoru Yang

    2011-01-01

    The kinetics and mechanism of poly(phenylene ether)\\/epoxy resin (PPE\\/EP) cure system were investigated using an advanced iso-convensional method (AICM). The curing experiments of a PPE\\/EP cure system with different PPE\\/EP ratios were carried out by means of non-isothermal differential scanning calorimetry (DSC) with different heating rates of 5, 10, 15 and 20°C\\/min. From the DSC curves, it was shown that

  18. Characterization of Rabbit Ear Skin as a Skin Model for in vitro Transdermal Permeation Experiments: Histology, Lipid Composition and Permeability

    Microsoft Academic Search

    S. Nicoli; C. Padula; V. Aversa; B. Vietti; P. W. Wertz; A. Millet; F. Falson; P. Govoni; P. Santi

    2008-01-01

    Aim: The aim of this work was to characterize rabbit ear skin in view of its use in transdermal permeation experiments. Method: The characterization included histological analysis of the tissue, qualitative and quantitative analysis of stratum corneum (SC) lipids, differential scanning calorimetry and permeation experiments (caffeine, nicotinamide, progesterone). As a reference, pig ear skin was used. Results: The results obtained

  19. Simultaneous heat-flow differential calorimetry and thermogravimetry for fast determination of sorption isotherms and heat of sorption in environmental or food engineering

    Microsoft Academic Search

    Jean-Henry Ferrasse; Didier Lecomte

    2004-01-01

    A new experimental technique is described for the determination of desorption characteristics for engineering purposes. A TGA-DSC set-up is used in isothermal mode to achieve the thermal desorption of deformable standard materials like microcrystalline cellulose and kaolin in dry air. Assumptions on heat and mass transfer are made and discussed in order to derive desorption isotherms and heat of sorptions

  20. Early event of protein folding studied by time-resolved photoacoustic calorimetry

    Microsoft Academic Search

    Wunshain Fann; Hsin-Liang Chen; Jen-Tse Huang; Pei-Yeh R. Chen; Chung Tien Lee; Sunney I. Chan

    2003-01-01

    Recently, various methods including temperature jump and hydro-dynamics focusing have been used to study early event of protein folding. In this paper, we propose to use time-resolved photoacoustic (PAC) to study protein folding from nanoseconds to microseconds. The experiment use photolabile linkers to \\

  1. The Compass Experiment at CERN

    SciTech Connect

    Magnon, A. [DAPNIA/SPhN, CEA-Saclay, F91191 Gif-Sur-Yvette Cedex (France)

    2005-02-10

    The COMPASS experiment at the CERN SPS has a broad physics program focused on the study of the spin structure of the nucleon and on hadron spectroscopy. Key measurements for the spin program are the gluon contribution to the spin of the nucleon, flavor dependent quark spin distribution, and the measurement of the transverse spin structure function. The apparatus consists of a two-stage spectrometer designed for high data rates and equipped with high-resolution tracking, particle identification, electromagnetic and hadronic calorimetry. Data taking has started in 2002. Following the CERN SPS shut down in 2005, the experiment will resume data taking in 2006 and is planned to continue (at least) until 2010. Few hundreds of Terabytes of data are put on tape each year. Out of this large amount of data first important physics results have been obtained.

  2. Synthesis, growth, crystal structure, EDX, UV-vis-NIR and DSC studies of L-proline lithium bromide monohydrate-A new semiorganic compound

    NASA Astrophysics Data System (ADS)

    Shkir, Mohd.; Alfaify, S.; Ajmal Khan, M.; Dieguez, Ernesto; Perles, Josefina

    2014-04-01

    L-Proline lithium bromide monohydrate (LPLBM) was synthesized and its good quality bulk single crystals of size ~55×10×8 mm3 were grown for the first time. Structural analysis was carried out by using single crystal X-ray diffraction and confirms that the crystal belongs to monoclinic system with space group P21. The lattice parameters of the titled compound was found to be a=8.0347(7) Å, b=5.1469(4) Å, c=10.6218 Å, ?=?=90°, ?=104.249(2)° and unit cell volume V=425.74(6) Å3. Elemental analysis was done by electron diffraction X-ray spectroscopy. Optical study shows that the grown crystals are highly transparent (~80%) in entire testing range. Optical band gap was calculated and found to be 5.7 eV. DSC study shows that the grown crystals are thermally stable up to 273 °C and two low temperature phase transitions were observed at -44.66 and 43.95 °C.

  3. Evaluating the Feasibility of an Agglomerative Hierarchy Clustering Algorithm for the Automatic Detection of the Arterial Input Function Using DSC-MRI

    PubMed Central

    Yin, Jiandong; Yang, Jiawen; Guo, Qiyong

    2014-01-01

    During dynamic susceptibility contrast-magnetic resonance imaging (DSC-MRI), it has been demonstrated that the arterial input function (AIF) can be obtained using fuzzy c-means (FCM) and k-means clustering methods. However, due to the dependence on the initial centers of clusters, both clustering methods have poor reproducibility between the calculation and recalculation steps. To address this problem, the present study developed an alternative clustering technique based on the agglomerative hierarchy (AH) method for AIF determination. The performance of AH method was evaluated using simulated data and clinical data based on comparisons with the two previously demonstrated clustering-based methods in terms of the detection accuracy, calculation reproducibility, and computational complexity. The statistical analysis demonstrated that, at the cost of a significantly longer execution time, AH method obtained AIFs more in line with the expected AIF, and it was perfectly reproducible at different time points. In our opinion, the disadvantage of AH method in terms of the execution time can be alleviated by introducing a professional high-performance workstation. The findings of this study support the feasibility of using AH clustering method for detecting the AIF automatically. PMID:24932638

  4. Eric J. Hall, DSc David J. Brenner, DSc

    E-print Network

    Brenner, David Jonathan

    and personnel Radiology and radiologists Published online 10.1148/radiol.2291030990 Radiology 2003; 229:18­19 1 From the Center for Radiological Re- search, Columbia University, 630 W 168th St, New York, NY 10024 Not Support the Suggestion that Exposure to Low Doses of X Rays Increases Longevity1 Wouldn't it be wonderful

  5. Measuring thermal diffusivity of mechanical and optical grades of polycrystalline diamond using an AC laser calorimetry method

    SciTech Connect

    Rule, Toby D. [II-VI Incorporated; Cai, Wei [ORNL; Wang, Hsin [ORNL

    2013-01-01

    Because of its extremely high thermal conductivity, measuring the thermal conductivity or diffusivity of optical-grade diamond can be challenging. Various methods have been used to measure the thermal conductivity of thick diamond films. For the purposes of commercial quality control, the AC laser calorimetry method is appealing because it enables fairly rapid and convenient sample preparation and measurement. In this paper, the method is used to measure the thermal diffusivity of optical diamond. It is found that sample dimensions and measurement parameters are critical, and data analysis must be performed with great care. The results suggest that the method as it is applied to optical-grade diamond could be enhanced by a more powerful laser, higher frequency beam modulation, and post-processing based on 2D thermal simulation.

  6. Determination of Volatility of Ionic Liquids at the Nanoscale by means of Ultra-Fast Scanning Calorimetry - the Method

    NASA Astrophysics Data System (ADS)

    Ahrenberg, Mathias; Beck, Martin; Schmidt, Christin; Verevkin, Sergey P.; Kessler, Olaf; Kragl, Udo; Schick, Christoph

    2015-03-01

    We present a new method for the determination of the vapour pressure of low volatile compounds using differential fast scanning calorimetry. We have developed and proven this method using the ionic liquids [EMIm][NTf2] and [EMIm][NO3] at temperatures up to 750 K and in different atmospheres to distinguish between decomposition and evaporation1. It was demonstrated that evaporation is still the dominating process of mass loss even at temperatures 100 K above the onset of decomposition as measured with common techniques, e.g TGA. Since the method allows very high heating rates (up to 106 K/s)2, much higher temperatures can be reached in the measurement of the vapour pressure as compared to common devices without significant decomposition of the ionic liquid. Furthermore, this method represents an improvement of the boiling point estimation of ILs due to the large accessible temperature range of mass loss rate determination.

  7. Limitations of amorphous content quantification by isothermal calorimetry using saturated salt solutions to control relative humidity: alternative methods.

    PubMed

    Khalef, Nawel; Pinal, Rodolfo; Bakri, Aziz

    2010-04-01

    Despite the high sensitivity of isothermal calorimetry (IC), reported measurements of amorphous content by this technique show significant variability even for the same compound. An investigation into the reasons behind such variability is presented using amorphous lactose and salbutamol sulfate as model compounds. An analysis was carried out on the heat evolved as a result of the exchange of water vapor between the solid sample during crystallization and the saline solution reservoir. The use of saturated salt solutions as means of control of the vapor pressure of water within sealed ampoules bears inherent limitations that lead in turn to the variability associated with the IC technique. We present an alternative IC method, based on an open cell configuration that effectively addresses the limitations encountered with the sealed ampoule system. The proposed approach yields an integral whose value is proportional to the amorphous content in the sample, thus enabling reliable and consistent quantifications. PMID:19774655

  8. Standard enthalpies of formation of some 3d transition metal silicides by high temperature direct synthesis calorimetry

    Microsoft Academic Search

    S. V Meschel; O. J Kleppa

    1998-01-01

    The standard enthalpies of formation of some 3d transition metal silicides have been measured by high temperature direct synthesis calorimetry at 1473±2 K. The following results, in kJ (mole of atoms)?1, are reported: ScSi: (?82.3±2.1); TiSi: (?72.6±1.9); Ti5Si3: (?73.8±2.0); Ti5Si4: (?78.5±2.1); V5Si3: (?59.0±2.0); V3Si: (?46.4±1.5); Cr5Si3: (?33.6±1.0); Cr3Si: (?27.2±1.1); CrSi: (?34.2±1.6); Mn5Si3: (?34.0±1.2); MnSi: (?39.4±1.7); FeSi: (?38.6±1.8); CoSi: (?49.3±1.3); Co2Si:

  9. Measurement of optical absorption by calorimetry and analysis of a solar collector

    SciTech Connect

    Allen, L.C.; Wallace, J.; Deutscher, G.; Lindenfeld, P.

    1988-01-01

    An apparatus is described for the measurement of absorptance, emittance, and selectivity. It can be used to illustrate the relative importance of heat losses by radiation, conduction, and convection in a solar collector, as well as the effects of selectivity and of full or partial evacuation on the efficiency. The apparatus can be constructed in a reasonably well-equipped departmental machine shop, and is suitable for projects or experiments by advanced undergraduate students.

  10. Experimental Studies on Minimum Heat Release Rates for Flashover with Oxygen Consumption Calorimetry

    Microsoft Academic Search

    W. K. Chow; Y. Gao; H. Dong; G. W. Zou; Z. Luo; L. Meng

    2003-01-01

    Studies on minimum beat release rates for flashover in a compartment fire will be reported in this paper. Experiments were carried out in a chamber with dimensions similar to that in the standard ISO9705 Room-Corner Fire test. This chamber is located inside a new full-scale burning facility, the PolyU\\/HEU Assembly Calorimeter, at the remote areas of Northern China. This is

  11. Modulated temperature differential scanning calorimetry: Cure, vitrification, and devitrification of thermosetting systems

    Microsoft Academic Search

    G. Van Assche; A. Van Hemelrijck; H. Rahier; B. Van Mele

    1997-01-01

    Vitrification of a reacting thermosetting system occurs when its glass transition temperature, Tg, rises to the reaction temperature, T. This phenomenon can occur in both isothermal and non-isothermal conditions, depending on the temperatures or heating rates used, the reactivity of the system, and the evolution of Tg with conversion. After vitrification, the reaction proceeds in mobility-restricted conditions. In non-isothermal experiments

  12. Negative pressure-temperature slopes for reactions forming MgSiO3 perovskite from calorimetry

    Microsoft Academic Search

    E. Ito; M. Akaogi; L. Topor; A. Navrotsky

    1990-01-01

    A new and sensitive differential drop solution calorimetric technique was developed for very small samples. A single experiment using one 5.18-milligram sample of perovskite, synthesized at 25 GPa and 1873 Kelvin, gave 110.1 + or - 4.1 kilojoules\\/mole for the enthalpy of the ilmenite-perovskite transition in MgSiO3. The thermodynamics of the reaction of MgSiO3 (ilmenite) to MgSiO3 (perovskite) and of

  13. Active optical fibres in modern particle physics experiments

    Microsoft Academic Search

    Carsten Patrick Achenbach

    2004-01-01

    In modern particle physics experiments wavelength-shifting and scintillating\\u000afibres based on plastic polymers are used for tracking and calorimetry. In this\\u000areview the role of photon trapping efficiencies, transmission functions and\\u000asignal response times for common multimode active fibres is discussed.\\u000aNumerical simulations involving three dimensional tracking of skew rays through\\u000acurved fibres demonstrate the characteristics of trapped light. Of

  14. Heat of Adsorption of Naphthalene on Pt(111) Measured by Adsorption Calorimetry J. Michael Gottfried, Ebbe K. Vestergaard, Parthasarathi Bera, and Charles T. Campbell*

    E-print Network

    Campbell, Charles T.

    adsorption isotherms to determine the heat of adsorption. Since the early years of the past decade, singleHeat of Adsorption of Naphthalene on Pt(111) Measured by Adsorption Calorimetry J. Michael: June 29, 2006 The heat of adsorption of naphthalene on Pt(111) at 300 K was measured with single

  15. The Interaction between PEO-PPO-PEO Triblock Copolymers and Ionic Surfactants in Aqueous Solution Studied Using Light Scattering and Calorimetry

    E-print Network

    Loh, Watson

    Studied Using Light Scattering and Calorimetry Jo1rgen Jansson,,$ Karin Schille´n,*, Gerd Olofsson charged. The relaxation time distributions from dynamic light scattering are monomodal and the electrostatic interaction is evidenced in both the static and the dynamic light scattering results

  16. Thermal conductivity measurements for small molecule organic solid materials using modulated differential scanning calorimetry (MDSC) and data corrections for sample porosity

    Microsoft Academic Search

    Yannan Lin; Zhenqi Shi; Peter L. D. Wildfong

    2010-01-01

    A method for measuring the thermal conductivity (k) of small molecule organic solid materials using modulated differential scanning calorimetry (MDSC) is demonstrated. Sample preparation required powder consolidation, unavoidably introducing air voids into compacts. Supporting equations for the technique were modified to include a porosity term (?), and the theoretical quadratic relationship between k and ? was confirmed by experimental measurements

  17. The Effect of Ergosterol on Dipalmitoylphosphatidylcholine Bilayers: A Deuterium NMR and Calorimetric Study

    Microsoft Academic Search

    Ya-Wei Hsueh; Kyle Gilbert; C. Trandum; M. Zuckermann; Jenifer Thewalt

    2005-01-01

    We have studied the effect of ergosterol, an important component of fungal plasma membranes, on the physical properties of dipalmitoylphosphatidylcholine (DPPC) multibilayers using deuterium nuclear magnetic resonance (2H NMR) and differential scanning calorimetry (DSC). For the 2H NMR experiments the sn-1 chain of DPPC was perdeuterated and NMR spectra were taken as a function of temperature and ergosterol concentration. The

  18. IGNITION AND PYROLISIS OF EXPLOSIVE COMPONENTS

    Microsoft Academic Search

    S. Almada; J. Campos; J. C. Gois

    Pyrolisis reactions, existing in explosive components and mixtures, are very difficult to follow by experiments, because these processes are very fast and proceed with increasing pressure and temperature. The thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) tests and conventional cook-off methods do not give precise and correct answer to the problem of detecting the life time of chemical explosive or

  19. Thermal Properties of Electrospun Poly(Lactic Acid) Membranes

    Microsoft Academic Search

    V. Sencadas; C. M. Costa; G. Botelho; C. Caparrós; C. Ribeiro; J. L. Gómez-Ribelles; S. Lanceros-Mendez

    2012-01-01

    Poly(lactic acid) (PLA) electrospun membranes were obtained by electrospinning and characterized by scanning electron microscopy (SEM) and thermal analysis. The polymer membranes showed a random fiber distribution with a mean diameter of 1 ?m (±300 nm). Differential scanning calorimetry (DSC) experiments showed that the membranes had a glass transition, cold crystallization, and melting temperatures of 54, 90, and 151°C, respectively.

  20. Collider Physics: SDC/SSC liquified fiber calorimetry. [Physics Dept. , Texas A M Univ

    SciTech Connect

    White, J.T.; Huson, F.R.

    1992-01-01

    Most effort was directed toward the D-Zero experiment at Fermilab. Over 3 pb[sup [minus]1] of high-quality physics data have been obtained. Analysis of the results (wino-zino physics, squark physics), D-zero data acquisition systems efforts, and level-1 and level-2 trigger work are described. Other work concerned detector development for use at the SSC. This technology consists of using liquid scintillator-filled tubes as scintillating fibers for a calorimeter.'' The key issues were to demonstrate that the liquid fibers were sufficiently rad-hard and to demonstrate that fibers with sufficiently long attenuation length could be found to satisfy the resolution requirements; both constraints could be satisfied.

  1. Collider Physics: SDC/SSC liquified fiber calorimetry. Progress report, 1992

    SciTech Connect

    White, J.T.; Huson, F.R.

    1992-12-31

    Most effort was directed toward the D-Zero experiment at Fermilab. Over 3 pb{sup {minus}1} of high-quality physics data have been obtained. Analysis of the results (wino-zino physics, squark physics), D-zero data acquisition systems efforts, and level-1 and level-2 trigger work are described. Other work concerned detector development for use at the SSC. This technology consists of using liquid scintillator-filled tubes as scintillating fibers for a ``calorimeter.`` The key issues were to demonstrate that the liquid fibers were sufficiently rad-hard and to demonstrate that fibers with sufficiently long attenuation length could be found to satisfy the resolution requirements; both constraints could be satisfied.

  2. Negative Pressure-Temperature Slopes for Reactions Formign MgSiO3 Perovskite from Calorimetry.

    PubMed

    Ito, E; Akaogi, M; Topor, L; Navrotsky, A

    1990-09-14

    A new and sensitive differential drop solution calorimetric technique was developed for very small samples. A single experiment using one 5.18-milligram sample of perovskite, synthesized at 25 gigapascals and 1873 Kelvin, gave 110.1 +/- 4.1 kilojoules per mole for the enthalpy of the ilmenite-pervoskite transition in MgSiO(3). The thermodynamics of the reaction of MgSiO(3) (ilmenite) to MgSiO(3) (perovskite) and of Mg(2)SiO(4) (spinel) to MgSiO(3) (pervoskite) and MgO (periclase) were assessed. Despite uncertainties in heat capacity and molar volume at high pressure and temperature, both reactions clearly have negative pressure-temperature slopes, -0.005 +/- 0.002 and -0.004 +/- 0.002 gigapascals per Kelvin, respectively. The latter may be insufficiently negative to preclude whole-mantle convection. PMID:17835541

  3. The neutron diffraction study, calorimetry and spontaneous polarization of pyridinium perrhenate at 350, 300 and 100 K

    NASA Astrophysics Data System (ADS)

    Ma?uszy?ska, Hanna; Cousson, Alain; Czarnecki, Piotr

    2010-06-01

    The crystal and molecular structure of pyridinium perrhenate [H5C5NH] + [ReO4] - (hereafter referred to as PyReO4) was determined by single-crystal neutron diffraction at 350, 300 and 100 K. The neutron study confirmed the x-ray diffraction results in all three phases. The three temperature-dependent polymorphs are orthorhombic, with the following sequence of phases: Cmcm\\longrightarrow Cmc2_{1}\\longrightarrow Pbca , with the a lattice parameter doubled. In the two high temperature phases the pyridinium cations display a rotational disorder while the perrhenate anions are well ordered. The low temperature phase is fully ordered. The neutron results allow for a very precise description of the distribution of the nitrogen atoms in the disordered pyridinium cation, which enables us to analyse the calorimetric and spontaneous polarization measurements. The results from the DSC and pyroelectric measurements point to a paraelectric (350 K), ferroelectric (300 K) with the Curie point at 336 K and antiferroelectric (100 K) crystal phases. The phase transition at 336 K can be classified as an order-disorder ferroelectric with a small displacive component.

  4. PHOENIX: A Scoring Function for Affinity Prediction Derived Using High-Resolution Crystal Structures and Calorimetry Measurements

    PubMed Central

    Tang, Yat T.; Marshall, Garland R.

    2011-01-01

    Binding affinity prediction is one of the most critical components to computer-aided structure-based drug design. Despite advances in first-principle methods for predicting binding affinity, empirical scoring functions that are fast and only relatively accurate are still widely used in structure-based drug design. With the increasing availability of X-ray crystallographic structures in the Protein Data Bank and continuing application of biophysical methods such as isothermal titration calorimetry to measure thermodynamic parameters contributing to binding free energy, sufficient experimental data exists that scoring functions can now be derived by separating enthalpic (?H) and entropic (T?S) contributions to binding free energy (?G). PHOENIX, a scoring function to predict binding affinities of protein-ligand complexes, utilizes the increasing availability of experimental data to improve binding affinity predictions by the following: model training and testing using high-resolution crystallographic data to minimize structural noise, independent models of enthalpic and entropic contributions fitted to thermodynamic parameters assumed to be thermodynamically biased to calculate binding free energy, use of shape and volume descriptors to better capture entropic contributions. A set of 42 descriptors and 112 protein-ligand complexes were used to derive functions using partial least squares for change of enthalpy (?H) and change of entropy (T?S) to calculate change of binding free energy (?G), resulting in a predictive r2 (r2pred) of 0.55 and a standard error (SE) of 1.34 kcal/mol. External validation using the 2009 version of the PDBbind “refined set” (n = 1612) resulted in a Pearson correlation coefficient (Rp) of 0.575 and a mean error (ME) of 1.41 pKd. Enthalpy and entropy predictions were of limited accuracy individually. However, their difference resulted in a relatively accurate binding free energy. While the development of an accurate and applicable scoring function was an objective of this study, the main focus was evaluation of the use of high-resolution X-ray crystal structures with high-quality thermodynamic parameters from isothermal titration calorimetry for scoring function development. With the increasing application of structure-based methods in molecular design, this study suggests that using high-resolution crystal structures, separating enthalpy and entropy contributions to binding free energy, and including descriptors to better capture entropic contributions may prove to be effective strategies towards rapid and accurate calculation of binding affinity. PMID:21214225

  5. Thermodynamic study of the micellization of zwitterionic surfactants and their interaction with polymers in water by isothermal titration calorimetry.

    PubMed

    Brinatti, César; Mello, Laura Bissoli; Loh, Watson

    2014-06-01

    The micellization of a homologous series of zwitterionic surfactants, a group of sulfobetaines, was studied using isothermal titration calorimetry (ITC) in the temperature range from 15 to 65 °C. The increase in both temperature and the alkyl chain length leads to more negative values of ?Gmic(0) , favoring the micellization. The entropic term (?Smic(0)) is predominant at lower temperatures, and above ca. 55-65 °C, the enthalpic term (?Hmic(0)) becomes prevalent, figuring a jointly driven process as the temperature increases. The interaction of these sulfobetaines with different polymers was also studied by ITC. Among the polymers studied, only two induced the formation of micellar aggregates at lower surfactant concentration: poly(acrylic acid), PAA, probably due to the formation of hydrogen bonds between the carboxylic group of the polymer and the sulfonate group of the surfactant, and poly(sodium 4-styrenesulfonate), PSS, probably due to the incorporation of the hydrophobic styrene group into the micelles. The prevalence of the hydrophobic and not the electrostatic contributions to the interaction between sulfobetaine and PSS was confirmed by an increased interaction enthalpy in the presence of electrolytes (NaCl) and by the observation of a significant temperature dependence, the latter consistent with the proposed removal of hydrophobic groups from water. PMID:24823937

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

    PubMed

    Bye, Jordan W; Falconer, Robert J

    2015-06-01

    Pressure perturbation calorimetry (PPC) was used to study the relationship between water and sodium salts with a range of different anions. At temperatures around 25 °C the heat on pressurisation (?Q) from 1 to 5 bar was negative for all solutions relative to pure water. The raw data showed that as the temperature rose, the gradient was positive relative to pure water and the transition temperature where ?Q was zero was related to anion surface charge density and was more pronounced for the low-charge density anions. A three component model was developed comprising bulk water, the hydration layer and the solute to calculate the molar expansivity of the hydration layer around the ions in solution. The calculated molar expansivities of water in the hydration layer around the ions were consistently less than pure water. ?Q at different disodium hydrogen phosphate concentrations showed that the change in molar enthalpy relative to pure water was not linear even as it approached infinite dilution suggesting that while hydration layers can be allocated to the water around ions this does not rule out interactions between water and ions extending beyond the immediate hydration layer. PMID:25959090

  7. Characterization of Streptococcus pneumoniae thymidylate kinase: steady-state kinetics of the forward reaction and isothermal titration calorimetry.

    PubMed Central

    Petit, Chantal M; Koretke, Kristin K

    2002-01-01

    Thymidylate kinase (TMK) catalyses the phosphorylation of dTMP to form dTDP in both the de novo and salvage pathways of dTTP synthesis. The tmk gene from the bacterial pathogen Streptococcus pneumoniae was identified. The gene, encoding a 212-amino-acid polypeptide (23352 Da), was cloned and overexpressed in Escherichia coli with an N-terminal hexahistidine tag. The enzyme was purified to homogeneity, and characterized in the forward reaction. The pH profile of TMK indicates that its activity is optimal at pH 8.5. The substrate specificity of the enzyme was examined; it was found that not only ATP, but also dATP and to a lesser extent CTP, could act as phosphate donors, and dTMP and dUMP could serve as phosphate acceptors. Furthermore, AZT-MP (3'-azido-3'-deoxythymidine 5'-monophosphate) was shown not to be a substrate for S. pneumoniae TMK. Steady-state kinetics and inhibition studies with adenosine 5'-[beta-thio]diphosphate and dTDP in addition to isothermal titration calorimetry were performed. The data showed that binding follows an ordered pathway, in which ATP binds first with a K(m) of 235 +/- 46 microM and a K(d) of 116 +/- 3 microM, and dTMP binds secondly with a K(m) of 66 +/- 12 microM and a K(d) of 53 +/- 2 microM. PMID:11964185

  8. Intrinsic thermodynamics of 4-substituted-2,3,5,6-tetrafluorobenzenesulfonamide binding to carbonic anhydrases by isothermal titration calorimetry.

    PubMed

    Zubrien?, Asta; Smirnovien?, Joana; Smirnov, Alexey; Mork?nait?, Vaida; Michailovien?, Vilma; Jachno, Jelena; Juozapaitien?, Vaida; Norvaišas, Povilas; Manakova, Elena; Gražulis, Saulius; Matulis, Daumantas

    2015-10-01

    Para substituted tetrafluorobenzenesulfonamides bind to carbonic anhydrases (CAs) extremely tightly and exhibit some of the strongest known protein-small ligand interactions, reaching an intrinsic affinity of 2 pM as determined by displacement isothermal titration calorimetry (ITC). The enthalpy and entropy of binding to five CA isoforms were measured by ITC in two buffers of different protonation enthalpies. The pKa values of compound sulfonamide groups were measured potentiometrically and spectrophotometrically, and enthalpies of protonation were measured by ITC in order to evaluate the proton linkage contributions to the observed binding thermodynamics. Intrinsic means the affinity of a sulfonamide anion for the Zn bound water form of CAs. Fluorination of the benzene ring significantly enhanced the observed affinities as it increased the fraction of deprotonated ligand while having little impact on intrinsic affinities. Intrinsic enthalpy contributions to the binding affinity were dominant over entropy and were more exothermic for CA I than for other CA isoforms. Thermodynamic measurements together with the X-ray crystallographic structures of protein-ligand complexes enabled analysis of structure-activity relationships in this enzyme ligand system. PMID:26079542

  9. Archeomagnetic dating of the eruption of Xitle volcano (Mexico) from a reappraisal of the paleointensity with the MSP-DSC protocol.

    NASA Astrophysics Data System (ADS)

    Bravo-Ayala, Manuel; Camps, Pierre; Alva-Valdivia, Luis; Poidras, Thierry; Nicol, Patrick

    2014-05-01

    The Xitle volcano, located south of Mexico City, is a monogenic volcano that has provided seven lava flows in a time interval of a few years. The age of these eruptions, estimated by means of radiocarbon dates on charcoal from beneath the flows, is still very poorly known, ranging from 4765±90 BC to 520±200 AD (see Siebe, JVGR, 2000 for a review). This lava field was emplaced over the archaeological city of Cuicuilco whose occupation is estimated between 700 BC and 150 AD. Thus a question is still pending: Is the downfall of Cuicuilco directly attributable to the eruption of Xitle? It seems that the answer is negative if we consider the latest radiocarbon dating by Siebe (2000), which sets the age of the eruption to 280±35 AD, that is significantly younger to the abandon of the city. Because this new age has direct implications on the history of the movements of ancient populations in the Central Valley of Mexico, we propose in the present study to check this estimate by archaeomagnetic dating. Xitle lava have been investigated several times for paleomagnetism, including directional analyses and absolute paleointensity determinations (see Alva, EPS, 57, 839-853, 2005 for a review). The characteristic Remanence direction is precisely determined. It is much more difficult to estimate precisely the paleointensity with the Thellier method: values scatter between 40 and 90 ?T in a single flow (Alva, 2005). We propose here to estimate the paleointensity by means of the MSP-DSC protocol (Fabian and Leonhardt, 2010) with the new ultra-fast heating furnace FUReMAG developed in Montpellier (France). The sampling was performed along four profiles, one vertical through the entire thickness of the flow and three horizontal (at the top, middle and the bottom of the flow). Our preliminary results show that there is no difference between the values found in the different profiles, all providing a value around 62 ?T. The comparison of our results (Dec = 359.0°, Inc = 35.2°, F=62.8±1.1 ?T) with the model CALS3K.4 for secular variation provided an Archaeomagnetic age between 176 BC and 58 BC at 95% significance value. This age is consistent with the hypothesis of archaeological destruction and the abandonment of Cuicuilco during the eruption of the Xitle volcano.

  10. Avalanche correlations in the martensitic transition of a Cu-Zn-Al shape memory alloy: analysis of acoustic emission and calorimetry.

    PubMed

    Baró, Jordi; Martín-Olalla, José-María; Romero, Francisco Javier; Gallardo, María Carmen; Salje, Ekhard K H; Vives, Eduard; Planes, Antoni

    2014-03-26

    The existence of temporal correlations during the intermittent dynamics of a thermally driven structural phase transition is studied in a Cu-Zn-Al alloy. The sequence of avalanches is observed by means of two techniques: acoustic emission and high sensitivity calorimetry. Both methods reveal the existence of event clustering in a way that is equivalent to the Omori correlations between aftershocks in earthquakes as are commonly used in seismology. PMID:24599153

  11. Calorimetry of silicate melts at 1773 K: measurement of enthalpies of fusion and of mixing in the systems diopside-anorthite-albite and anorthite-forsterite

    Microsoft Academic Search

    Alexandra Navrotsky; David Ziegler; Richard Oestrike; Papu Maniar

    1989-01-01

    Transposed-temperature-drop calorimetry, using a Setaram HT 1500 calorimeter, was used to study directly the melting at 1773 K of mixtures of crystalline albite, anorthite, and diopside and of anorthite and forsterite. The enthalpy of albite at 1000–1773 K, starting with both crystalline and glassy samples, was also measured. The results confirm previously measured enthalpies of fusion of albite, diopside and

  12. Versatile peroxidase degradation of humic substances: use of isothermal titration calorimetry to assess kinetics, and applications to industrial wastes.

    PubMed

    Siddiqui, Khawar Sohail; Ertan, Haluk; Charlton, Timothy; Poljak, Anne; Daud Khaled, A K; Yang, Xuexia; Marshall, Gavin; Cavicchioli, Ricardo

    2014-05-20

    The kinetic constants of a hybrid versatile-peroxidase (VP) which oxidizes complex polymeric humic substances (HS) derived from lignin (humic and fulvic acids) and industrial wastes were determined for the first time using isothermal titration calorimetry (iTC). The reaction conditions were manipulated to enable manganese-peroxidase (MnP) and/or lignin-peroxidase (LiP) activities to be evaluated. The peroxidase reactions exhibited varying degrees of product inhibition or activation; properties which have not previously been reported for VP enzymes. In contrast to previous work (Ertan et al., 2012) on small non-polymeric substrates (MnSO4, veratryl alcohol and dyes), all kinetic plots for polymeric HS were sigmoidal, lacked Michaelis-Menten characteristics, and were indicative of positive cooperativity. Under conditions when both LiP and MnP were active, the kinetic data fitted to a novel biphasic Hill Equation, and the rate of enzymatic reaction was significantly greater than the sum of individual LiP plus MnP activities implying synergistic activation. By employing size-exclusion chromatography and electrospray ionization mass spectrometry, the characteristics of the oxidative degradation products of the HS were also monitored. Our study showed that the allosteric behaviour of the VP enzyme promotes a high level of regulation of activity during the breakdown of model and industrial ligninolytic substrates. The work was extended to examine the kinetics of breakdown of industrial wastes (effluent from a pulp and paper plant, and fouled membrane solids extracted from a ground water treatment membrane) revealing unique, VP-mediated, kinetic responses. This work demonstrates that iTC can be successfully employed to study the kinetic properties of VP enzymes in order to devise reaction conditions optimized for oxidative degradation of HS present in materials used in a wide range of industries. PMID:24631722

  13. Phase equilibria of cholesterol/dipalmitoylphosphatidylcholine mixtures: sup 2 H nuclear magnetic resonance and differential scanning calorimetry

    SciTech Connect

    Vist, M.R.; Davis, J.H. (Univ. of Guelph, Ontario (Canada))

    1990-01-16

    Deuterium nuclear magnetic resonance spectroscopy and differential scanning calorimetry are used to map the phase boundaries of mixtures of cholesterol and chain-perdeuteriated 1,2-dipalmitoyl-sn-glycero-3-phosphocholine at concentrations from 0 to 25 mol % cholesterol. These distinct phases can be identified: the L{sub {alpha}} or liquid-crystalline phase, the gel phase, and a high cholesterol concentration phase, which we call the {beta} phase. The liquid-crystalline phase is characterized by highly flexible phospholipid chains with rapid axially symmetric reorientation; the gel phase has much more rigid lipid chains, and the motions are no longer axially symmetric on the {sup 2}H NMR time scale; the {beta} phase is characterized by highly ordered (rigid) chains and rapid axially symmetric reorientation. In addition, the authors identify three regions of two-phase coexistence. The first of these is a narrow L{sub {alpha}}/gel-phase coexistence region lying between 0 and about 6 mol % cholesterol at temperatures just below the chain-melting transition of the pure phospholipid/water dispersions, at 37.75{degree}C. The dramatic changes in the {sup 2}H NMR line shape which occur on passing through the phase transition are used to map out the boundaries of this narrow two-phase region. The boundaries of the second two-phase region are determined by {sup 2}H NMR difference spectroscopy, one boundary lying near 7.5 mol % cholesterol and running from 37 down to at least 30{degree}C; the other boundary lies near 22 mol % cholesterol and covers the same temperature range. The third two-phase lies above 37{degree}C, beginning at a eutectic point somewhere between 7.5 and 10 mol% cholesterol and ending at about 20 mol %. In this region, the L{sub {alpha}} and {beta} phases are in equilibrium.

  14. Liquid scintillator sampling calorimetry 

    E-print Network

    Dudgeon, R. Greg

    1994-01-01

    embedded in a lead matrix. Two prototypes employing l mm and 2mm fibers with 2mm and 4mm distance between each fiber respectively were designed, constructed and then tested in the test beam at Fermi National Accelerator Laboratory between the months...

  15. Heat release rate calorimetry

    Microsoft Academic Search

    Edwin E. Smith

    1996-01-01

    A simple, theoretically sound method for eliminating the effects of internal heat absorption on rate of heat release is described for the Ohio State University (OSU) Release Rate apparatus. By monitoring the temperature of metal walls and calculating the heat loss to surroundings caused by changes in wall temperature due to heat absorption, a complete energy balance on the system

  16. Liquid scintillator sampling calorimetry

    E-print Network

    Dudgeon, R. Greg

    1994-01-01

    to both can and PMTs by clear silicon cookies (Figures 2. 5 and 2. 6). A piece of light filter (see Section 3. 2. 1) fitted between each cookie and PMT. Care was taken to make sure the cookies were free of dust and that little or no air bubbles were...

  17. Fluence correction factors for graphite calorimetry in a low-energy clinical proton beam: I. Analytical and Monte Carlo simulations.

    PubMed

    Palmans, H; Al-Sulaiti, L; Andreo, P; Shipley, D; Lühr, A; Bassler, N; Martinkovi?, J; Dobrovodský, J; Rossomme, S; Thomas, R A S; Kacperek, A

    2013-05-21

    The conversion of absorbed dose-to-graphite in a graphite phantom to absorbed dose-to-water in a water phantom is performed by water to graphite stopping power ratios. If, however, the charged particle fluence is not equal at equivalent depths in graphite and water, a fluence correction factor, kfl, is required as well. This is particularly relevant to the derivation of absorbed dose-to-water, the quantity of interest in radiotherapy, from a measurement of absorbed dose-to-graphite obtained with a graphite calorimeter. In this work, fluence correction factors for the conversion from dose-to-graphite in a graphite phantom to dose-to-water in a water phantom for 60 MeV mono-energetic protons were calculated using an analytical model and five different Monte Carlo codes (Geant4, FLUKA, MCNPX, SHIELD-HIT and McPTRAN.MEDIA). In general the fluence correction factors are found to be close to unity and the analytical and Monte Carlo codes give consistent values when considering the differences in secondary particle transport. When considering only protons the fluence correction factors are unity at the surface and increase with depth by 0.5% to 1.5% depending on the code. When the fluence of all charged particles is considered, the fluence correction factor is about 0.5% lower than unity at shallow depths predominantly due to the contributions from alpha particles and increases to values above unity near the Bragg peak. Fluence correction factors directly derived from the fluence distributions differential in energy at equivalent depths in water and graphite can be described by kfl = 0.9964 + 0.0024·zw-eq with a relative standard uncertainty of 0.2%. Fluence correction factors derived from a ratio of calculated doses at equivalent depths in water and graphite can be described by kfl = 0.9947 + 0.0024·zw-eq with a relative standard uncertainty of 0.3%. These results are of direct relevance to graphite calorimetry in low-energy protons but given that the fluence correction factor is almost solely influenced by non-elastic nuclear interactions the results are also relevant for plastic phantoms that consist of carbon, oxygen and hydrogen atoms as well as for soft tissues. PMID:23629423

  18. Fluence correction factors for graphite calorimetry in a low-energy clinical proton beam: I. Analytical and Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Palmans, H.; Al-Sulaiti, L.; Andreo, P.; Shipley, D.; Lühr, A.; Bassler, N.; Martinkovi?, J.; Dobrovodský, J.; Rossomme, S.; Thomas, R. A. S.; Kacperek, A.

    2013-05-01

    The conversion of absorbed dose-to-graphite in a graphite phantom to absorbed dose-to-water in a water phantom is performed by water to graphite stopping power ratios. If, however, the charged particle fluence is not equal at equivalent depths in graphite and water, a fluence correction factor, kfl, is required as well. This is particularly relevant to the derivation of absorbed dose-to-water, the quantity of interest in radiotherapy, from a measurement of absorbed dose-to-graphite obtained with a graphite calorimeter. In this work, fluence correction factors for the conversion from dose-to-graphite in a graphite phantom to dose-to-water in a water phantom for 60 MeV mono-energetic protons were calculated using an analytical model and five different Monte Carlo codes (Geant4, FLUKA, MCNPX, SHIELD-HIT and McPTRAN.MEDIA). In general the fluence correction factors are found to be close to unity and the analytical and Monte Carlo codes give consistent values when considering the differences in secondary particle transport. When considering only protons the fluence correction factors are unity at the surface and increase with depth by 0.5% to 1.5% depending on the code. When the fluence of all charged particles is considered, the fluence correction factor is about 0.5% lower than unity at shallow depths predominantly due to the contributions from alpha particles and increases to values above unity near the Bragg peak. Fluence correction factors directly derived from the fluence distributions differential in energy at equivalent depths in water and graphite can be described by kfl = 0.9964 + 0.0024???zw-eq with a relative standard uncertainty of 0.2%. Fluence correction factors derived from a ratio of calculated doses at equivalent depths in water and graphite can be described by kfl = 0.9947 + 0.0024???zw-eq with a relative standard uncertainty of 0.3%. These results are of direct relevance to graphite calorimetry in low-energy protons but given that the fluence correction factor is almost solely influenced by non-elastic nuclear interactions the results are also relevant for plastic phantoms that consist of carbon, oxygen and hydrogen atoms as well as for soft tissues.

  19. Complexation of phenols and thiophenol by phosphine oxides and phosphates. Extraction, isothermal titration calorimetry, and ab initio calculations.

    PubMed

    Cuypers, Ruud; Burghoff, Bernhard; Marcelis, Antonius T M; Sudhölter, Ernst J R; de Haan, André B; Zuilhof, Han

    2008-11-20

    To develop a new solvent-impregnated resin system for the removal of phenols from water the complex formation of triisobutylphosphine sulfide (TIBPS), tributylphosphate (TBP), and tri-n-octylphosphine oxide (TOPO) with a series of phenols (phenol, thiophenol, 3-chlorophenol, 3,5-dichlorophenol, 4-cyanophenol, and pentachlorophenol) was studied. The investigation of complex formation between the extractants and the phenols in the solvent toluene was carried out using liquid-liquid extraction, isothermal titration calorimetry (ITC), and quantum chemical modeling (B3LYP/6-311+G(d,p)//B3LYP/6-311G(d,p) and MP2/6-311++G(2d,2p)//B3LYP/6-311G(d,p)). The equilibrium constant (binding affinity, Kchem), enthalpy of complex formation (DeltaH), and stoichiometry (N) were directly measured with ITC, and the entropy of complexation (DeltaS) was derived from these results. A first screening of K chem toward phenol revealed a very high binding affinity for TOPO, and very low binding affinities for the other extractants. Modeling results showed that although 1:1 complexes were formed, the TIBPS and TBP do not form strong hydrogen bonds. Therefore, in the remainder of the research only TOPO was considered. Kchem of TOPO for the phenols in toluene increased from 1,000 to 10,000 M(-1) in the order phenol < pentachlorophenol < 3-chlorophenol < 4-cyanophenol approximately 3,5-dichlorophenol (in line with their pKa values, except for pentachlorophenol) in the absence of water, while the stoichiometric ratio remained 1:1. In water-saturated toluene, the binding affinities are lower due to co-complexation of water with the active site of the extractant. The increase in binding affinity for TOPO in the phenol series was confirmed by a detailed ab initio study, in which Delta H was calculated to range from -10.7 kcal/mol for phenol to -13.4 kcal/mol for 4-cyanophenol. Pentachlorophenol was found to behave quite differently, showing a DeltaH value of -10.5 kcal/mol. In addition, these calculations confirm the formation of 1:1 H-bonded complexes. PMID:18959384

  20. Complexation of phenol and thiophenol by amine N-oxides: isothermal titration calorimetry and ab initio calculations.

    PubMed

    Cuypers, Ruud; Murali, Sukumaran; Marcelis, Antonius T M; Sudhölter, Ernst J R; Zuilhof, Han

    2010-11-15

    To develop a new solvent-impregnated resin (SIR) system for removal of phenols from water, the complex formation of dimethyldodecylamine N-oxide (DMDAO), trioctylamine N-oxide (TOAO), and tris(2-ethylhexyl)amine N-oxide (TEHAO) with phenol (PhOH) and thiophenol (PhSH) is studied. To this end we use isothermal titration calorimetry (ITC) and quantum chemical modeling (on B3LYP/6-311G(d,p)-optimized geometries: B3LYP/6-311+G(d,p), B3LYP/6-311++G(2d,2p), MP2/6-311+G(d,p), and spin component scaled (SCS) MP2/6-311+G(d,p); M06-2X/6-311+G(d,p)//M06-2X/6-311G(d,p), MP2 with an extrapolation to the complete basis set limit (MP2/CBS), as well as CBS-Q). The complexes are analyzed in terms of structural (e.g., bond lengths) and electronic elements (e.g., charges). Furthermore, complexation and solvent effects (in benzene, toluene, and mesitylene) are investigated by ITC measurements, yielding binding constants K, enthalpies ?H(0), Gibbs fre energies ?G(0), and entropies ?S(0) of complex formation, and stoichiometry N. The ITC measurements revealed strong 1:1 complex formation between both DMDAO-PhOH and TOAO-PhOH. The binding constant (K=1.7-5.7×10(4) M(-1)) drops markedly when water-saturated toluene was used (K=5.8×10(3) M(-1)), and ?-? interaction with the solvent is shown to be relevant. Quantum mechanical modeling confirms formation of stable 1:1 complexes with linear hydrogen bonds that weaken on attachment of electron-withdrawing groups to the amine N-oxide moiety. Modeling also showed that complexes with PhSH are much weaker than those with PhOH, and in fact too weak for ITC determination. CBS-Q incorrectly predicts equal or even higher binding enthalpies for PhSH than for PhOH, which invalidates it as a benchmark for other calculations. Data from the straightforward SCS-MP2 method without counterpoise correction show very good agreement with the MP2/CBS values. PMID:20973022

  1. Oxide Melt Solution Calorimetry of Fe2+ -bearing Oxides and Application to the Magnetite - Maghemite (Fe3O4-Fe8/3O4) system

    SciTech Connect

    Lilova, Kristina I.; Xu, Fen; Rosso, Kevin M.; Pearce, Carolyn I.; Kamali, Saeed; Navrotsky, Alexandra

    2012-01-01

    A consistent methodology for obtaining enthalpy of formation of Fe{sup 2+}-containing binary and multicomponent oxides using high temperature oxide melt solution calorimetry has been developed. The enthalpies of wuestite (FeO) and magnetite (Fe{sub 3}O{sub 4}) oxidation to hematite (Fe{sub 2}O{sub 3}) were measured using oxidative drop solution calorimetry in which the final product is dissolved ferric oxide. Two methods were applied: drop solution calorimetry at 1073 K in lead borate solvent and at 973 K in sodium molybdate, each under both oxygen flowing over and bubbling through the solvent, giving consistent results in agreement with literature values. The enthalpies of formation of all three iron oxides from the elements were obtained using a thermodynamic cycle involving the directly measured oxidative dissolution enthalpy of iron metal in sodium molybdate at 973 K and gave excellent consistency with literature data. The methodology was then applied to the magnetite - maghemite system. The enthalpy of mixing of the Fe{sub 3}O{sub 4}-Fe{sub 8/3}O{sub 4} spinel solid solution is exothermic and, 2 represented by a subregular (Margules) formalism, {Delta}H{sub mix} = x(1-x)(-63.36 {+-} 8.60(1-x) + 17.65 {+-} 6.40x) kJ/mol, where x is the mole fraction of magnetite. The entropies of mixing of the solid solution were calculated for different assumptions about the distribution of cations, charges, and vacancies in these defect spinels. The different models lead to only small differences in the entropy of mixing. Calculated free energies of mixing show no evidence for a solvus in the magnetite - maghemite system.

  2. On structural phase transitions in 4-aminopyridinium fluoroborate, [4-NH 2C 5H 5N][BF 4]: differential scanning calorimetry, dielectric and infrared studies

    NASA Astrophysics Data System (ADS)

    Czupi?ski, O.; Jakubas, R.; Pietraszko, A.

    2004-10-01

    Crystal structure of the 4-aminopyridinium tetrafluoroborate, [4-NH 2C 5H 5N][BF 4], has been determined at 293 K by means of X-ray diffraction as monoclinic space group, C2. The crystal shows a reach sequence of phase transition, four solid-solid transitions: at 250, 281, 388 and 485 K on heating. Most of the phase transitions, except that at 388 K, are clearly of first order and classified as an 'order-disorder' type. The rotational disorder both of cations and anions was studied by differential scanning calorimetry, dielectric and infrared spectroscopy. The low temperature phase transitions are associated with plastic crystal behavior.

  3. Isothermal calorimetry investigation of Li{sub 1+x}Mn{sub 2-y}Al{sub z}Oâ spinel

    Microsoft Academic Search

    W. Lu; I. Belharouak; S. H. Park; Y. K Sun; K. Amine

    2007-01-01

    The heat generation of LiMnâOâ, Li{sub 1.156}Mn{sub 1.844}Oâ, and Li{sub 1.06}Mn{sub 1.89}Al{sub 0.05}Oâ spinel cathode materials in a half-cell system was investigated by isothermal micro-calorimetry (IMC). The heat variations of the Li\\/LiMnâOâ cell during charging were attributed to the LiMnâOâ phase transition and order\\/disorder changes. This heat variation was largely suppressed when the stoichiometric spinel was doped with excess lithium

  4. Thermal phase behavior of 1-butyl-3-methylimidazolium hexafluorophosphate: Simultaneous measurements of the melting of two polymorphic crystals by Raman spectroscopy and calorimetry

    NASA Astrophysics Data System (ADS)

    Endo, Takatsugu; Nishikawa, Keiko

    2013-10-01

    The thermal phase behavior of 1-butyl-3-methylimidazolium hexafluorophosphate, which forms three polymorphic crystals (?, ?, and ?), has been re-investigated by the simultaneous measurements of Raman spectroscopy and calorimetry. The peak assigned to the phase change from ? to ? phase is found to be exothermic and, in striking contrast with a previous report, the peak for this transition is observed near 255 K by recooling and subsequent reheating of the ? phase. This finding enabled separate measurements of the melting points (285.8 and 285.3 K), fusion enthalpies (13.1 and 22.6 kJ mol-1), and entropies of the ? and ? phases, respectively.

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

    PubMed

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

    2015-06-01

    This paper focuses on the investigation of the interactions between the anti-HSA-mAb and its protein antigen using CZE, ACE, and isothermal titration calorimetry. The CZE revealed the formation of the anti-HSA-mAb·HSA and anti-HSA-mAb·(HSA)2 complexes and the binding constants determined by plotting the amount of the bound anti-HSA-mAb as a function of the concentration of HSA. The ACE provided information on the binding strength from the change in effective electrophoretic mobility of the anti-HSA-mAb. These two separation techniques estimated the presence of two binding sites. The equilibrium dissociation constant values obtained by CZE and ACE were found to be 2.26 × 10(-6) M for anti-HSA-mAb·HSA, 1.22 × 10(-6) M for anti-HSA-mAb·(HSA)2 and 4.45 × 10(-8) M for anti-HSA-mAb·HSA, 1.08 × 10(-7) M for anti-HSA-mAb·(HSA)2 , respectively. The dissociation constant data obtained by ACE were in congruence with the values obtained by isothermal titration calorimetry (2.74 × 10(-8) M, 1.04 × 10(-7) M). PMID:25522280

  6. Mechanistic investigation of mercury sorption by Brazilian pepper biochars of different pyrolytic temperatures based on X-ray photoelectron spectroscopy and flow calorimetry.

    PubMed

    Dong, Xiaoling; Ma, Lena Q; Zhu, Yingjia; Li, Yuncong; Gu, Binhe

    2013-01-01

    We investigated the mechanisms of Hg sorption onto biochars produced from Brazilian pepper (BP; Schinus terebinthifolius) at 300, 450, and 600 °C using different analytical techniques. The Hg sorption capacity of BP300, BP450, and BP600 was 24.2, 18.8, and 15.1 mg g(-1) based on Langmuir isotherm. FTIR data suggested the participation of phenolic hydroxyl and carboxylic groups in Hg sorption by biochars. XPS analysis showed that 23-31% and 77-69% of sorbed Hg was associated with carboxylic and phenolic hydroxyl groups in biochars BP300-450, whereas 91% of sorbed Hg was associated with a graphite-like domain on an aromatic structure in BP600 biochar, which were consistent with flow calorimetry data. Based on flow calorimetry, sorption of K and Ca onto biochar was exchangeable with the molar heat of sorption of 3.1 kJ mol(-1). By comparison, Hg sorption was via complexation with functional groups as it was not exchangeable by K or Ca with molar heat of sorption of -19.7, -18.3, and -25.4 kJ mol(-1) for BP300, BP450, and BP600. Our research suggested that Hg was irreversibly sorbed via complexation with phenolic hydroxyl and carboxylic groups in low temperature biochars (BP300 and BP450) and graphite-like structure in high temperature biochar (BP600). PMID:24040905

  7. Determination of the net energy content of canola meal from Brassica napus yellow and Brassica juncea yellow fed to growing pigs using indirect calorimetry.

    PubMed

    Heo, Jung Min; Adewole, Deborah; Nyachoti, Martin

    2014-07-01

    The net energy (NE) content of canola meals (CM; i.e. Brassica napus yellow and Brassica juncea yellow) in growing pigs was determined using an indirect calorimetry chamber or published prediction equations. The study was conducted as a completely randomized design (n=6), with (i) a basal diet and (ii) 2 diets containing 700?g/kg of the basal diet and 300?g/kg of either of the two varieties of CM. A total of 18 growing barrows were housed in metabolism crates for the determination of digestible (DE) and metabolizable (ME) energy. Thereafter, pigs were transferred to the indirect calorimetry chamber to determine heat production (HP). The NE contents of diets containing Brassica napus yellow and Brassica juncea yellow determined with the direct determination technique and prediction equations were 9.8 versus 10.3 MJ/kg dry matter (DM) and 10.2 versus 10.4 MJ/kg DM, respectively. Retained energy (RE) and fasting heat production (FHP) of diets containing Brassica napus yellow and Brassica juncea yellow were 5.5 versus 5.7 MJ/kg and 4.3 versus 4.5 MJ/kg, respectively, when measured with the direct determination technique and prediction equations. The NE contents of Brassica napus yellow and Brassica juncea yellow were determined to be 8.8 and 9.8 MJ/kg DM, respectively, using the direct determination technique. PMID:24720508

  8. Introduction Experiments

    E-print Network

    Escolano, Francisco

    Introduction Method Experiments Conclusions EBEM An Entropy-based EM Algorithm for Gaussian Mixture;Introduction Method Experiments Conclusions Outline 1 Introduction 2 Method Shannon entropy estimation Splitting a Kernel 3 Experiments Synthetic Data Experiments Image Data Experiments 4 Conclusions A

  9. Introduction Experiments

    E-print Network

    Escolano, Francisco

    Introduction Method Experiments Conclusions A New Feasible Approach to Multi-dimensional Scale;Introduction Method Experiments Conclusions Outline 1 Introduction 2 Method 3 Experiments 4 Conclusions P. Suau Experiments Conclusions Outline 1 Introduction 2 Method 3 Experiments 4 Conclusions P. Suau and F. Escolano

  10. Introduction Experiments

    E-print Network

    Escolano, Francisco

    Introduction Method Experiments Conclusions Robot Navigation Behaviors based on Omnidirectional WAF 2007 #12;Introduction Method Experiments Conclusions Outline 1 Introduction 2 Method Direction Estimation Approach Entropy estimation Entropy approximation Experiments OV-sonars Gradient threshold

  11. The effects of pH, NaCl and CaCl 2 on thermal denaturation characteristics of intramuscular connective tissue

    Microsoft Academic Search

    N Akta?

    2003-01-01

    The research was conducted with two different experiments on intramuscular connective tissue obtained from Longissimus dorsi muscle of 4-year-old beef carcasses. Differential scanning calorimetry (DSC) was used to determine the denaturation onset temperature (To), denaturation peak temperature (Tp), and denaturation enthalpy (?HD) of intramuscular connective tissue. In the first experiment, equilibration of the collagen in citrate buffers in the pH

  12. Shape memory response of ni2mnga and nimncoin magnetic shape memory alloys under compression 

    E-print Network

    Brewer, Andrew Lee

    2009-05-15

    .........................................................................32 IV Ni2MnGa RESULTS AND DISCUSSION ...................................................34 4.1 Testing Procedure.....................................................................................34 a. Differential Scanning Calorimetry (DSC....................................................................................35 4.2 DSC Results .............................................................................................36 4.3 SQUID Results.........................................................................................37 4.4 Thermal Cycling...

  13. The Observation and Study of ELP V5-120 Conformational Changes 

    E-print Network

    Zhou, Qian

    2012-10-24

    and secondary/tertiary structure formation. In this thesis, the collapse process of ELP was studied with differential scanning calorimetry (DSC). In DSC thermal cycling, a clear conformational transition was observed. Also, a transiently stable state of ELP V5...

  14. Detection of a minor amorphous phase in crystalline etoricoxib by dynamic mechanical analysis: comparison with Raman spectroscopy and modulated differential scanning calorimetry.

    PubMed

    Clas, Sophie-Dorothee; Lalonde, Karine; Khougaz, Karine; Dalton, Chad R; Bilbeisi, Rana

    2012-02-01

    Detection and quantification of the amorphous phase of etoricoxib bulk drug substances, a selective cycloogenase-2 inhibitor used for the treatment of osteoarthritis, rheumatoid arthritis, and dental pain, was carried out using modulated differential scanning calorimetry (MDSC), dynamic mechanical analysis (DMA), and Raman spectroscopy. Detection of amorphous content in pharmaceutical powders by DMA is a special application of dynamic mechanical spectroscopy. DMA was found to be a sensitive technique, able to detect the presence of an amorphous phase in a crystalline phase at concentrations as low as 0.5%. The limit of detection (LOD) determined for DMA was 2.5%. In comparison, Raman spectroscopy and MDSC had LOD values of 2% and 5% amorphous, respectively. PMID:21953620

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  16. Measurement of boundaries between two-phase and three-phase regions in emulsified systems by titration calorimetry; 2: Determination of phase compositions in three-phase systems

    SciTech Connect

    Smith, D.H.; Covatch, G.L. (Morgantown Energy Technology Center, WV (United States) Univ. of Oklahoma, Norman, OK (United States))

    1994-02-01

    It has been demonstrated that isoperibolic titration calorimetry can be used to determine the tie-triangles (i.e., compositions of conjugate top, middle, and bottom phases) of amphiphile/oil/water systems. Simple regressions to temperatures, heats, or their respective derivatives, measured as a function of system composition, gave multiple compositional points on each side of the tie-triangle. An equation for each side then was calculated from a regression to the respective set of compositional points. Finally, phase compositions were obtained by solving the equations for the respective sides of the tie-triangle for their three points of intersection. No dependence of the phase boundary points on the morphologies of the emulsions was found. Densities of 2-butoxyethanol from 24 to 50 C also are reported.

  17. Experience matters 1 Experience matters

    E-print Network

    Nelson, Jonathan D.

    of these theories best describes human information search. Experiment 1, which used natural sampling and experienceExperience matters 1 Experience matters: Information acquisition optimizes probability gain Jonathan D. Nelson Max Planck Institute for Human Development Craig R. M. McKenzie University of California

  18. Status of the CBM experiment

    NASA Astrophysics Data System (ADS)

    Heuser, Johann M.

    2015-05-01

    The Compressed Baryonic Matter (CBM) experiment at the Facility for Anti-Proton and Ion Research (FAIR) will explore the phase diagram of strongly interacting matter at highest net baryon densities and moderate temperatures. The CBM physics program will be started with beams delivered by the SIS 100 synchrotron, providing energies from 2 to 11 GeV/nucleon for heavy nuclei, up to 14 GeV/nucleon for light nuclei, and 29 GeV for protons. The highest net baryon densities will be explored with ion beams up to 45 GeV/nucleon energy delivered by SIS 300 in the next stage of FAIR. Collision rates up to 107 per second are required to produce very rare probes with unprecedented statistics in this energy range. Their signatures are complex. These conditions call for detector systems designed to meet the extreme requirements in terms of rate capability, momentum and spatial resolution, and a novel DAQ and trigger concept which is not limited by latency but by throughput. The article discusses the development status of the CBM sub-systems for charged particle tracking, vertex detection, electron/muon identification, hadron/time-of-flight measurement, electromagnetic and zero-degree calorimetry, in terms of prototypes and expected physics performance. The concept and development status of CBM's central detector, the Silicon Tracking System STS are presented in somewhat more detail.

  19. MicroBooNE: A New Liquid Argon Time Projection Chamber Experiment

    SciTech Connect

    Soderberg, M.

    2009-10-01

    Liquid Argon Time Projection Chamber detectors are well suited to study neutrino interactions, and are an intriguing option for future massive detectors capable of measuring the parameters that characterize neutrino oscillations. These detectors combine fine-grained tracking with calorimetry, allowing for excellent imaging and particle identification ability. In this talk the details of the MicroBooNE experiment, a 175 ton LArTPC which will be exposed to Fermilab's Booster Neutrino Beamline starting in 2011, will be presented. The ability of MicroBooNE to differentiate electrons from photons gives the experiment unique capabilities in low energy neutrino interaction measurements.

  20. Evaluation of PAN-based manganese dioxide composite for the sorptive removal of cesium-137 from aqueous solutions

    Microsoft Academic Search

    A. Nilchi; R. Saberi; S. Rasouli Garmarodi; A. Bagheri

    Hydrous manganese dioxide–polyacrylonitrile (MnO2–PAN) was chemically synthesized and evaluated, as an organic–inorganic composite material, for the removal of radio-contaminant cesium-137 from aqueous solutions. The physico-chemical characterization was carried out by Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), CHN elemental analysis, scanning electron microscopy (SEM), nitrogen adsorption–desorption studies and thermogravimetry-differential scanning calorimetry (TGA-DSC). Batch experiments were carried out as

  1. Influence of hydrogen bond, hydrophobic and electrovalent salt linkages on the transition temperature, enthalpy and activation energy in rat tail tendon (RTT) collagen fibre

    Microsoft Academic Search

    R. Usha; T. Ramasami

    1999-01-01

    The influence of hydrogen bonding, hydrophobic and electrostatic interactions on the thermal stability of rat tail tendon collagen fibre has been studied using differential scanning calorimetry (DSC) and hydrothermal isometric tension (HIT) experiments. The reagents used to study these effects are urea (hydrogen bonding), aqueous alcohols (hydrophobic) and 0.02M Tris-maleate buffer at pH 4–8 (electrostatic interactions). The peak temperature, enthalpy

  2. The valence and site occupancy of substituting metals in magnetite spinel structure Fe3-xMxO4 (M = Cr, Mn, Co and Ni) and their influence on thermal stability: An XANES and TG-DSC investigation

    NASA Astrophysics Data System (ADS)

    Liang, Xiaoliang; Zhong, Yuanhong; Zhu, Sanyuan; He, Hongping; Yuan, Peng; Zhu, Jianxi; Jiang, Zheng

    2013-01-01

    Four series of substituted magnetite (Fe3-xMxO4, M = Cr, Mn, Co and Ni) were characterized by X-ray diffraction (XRD), X-ray absorption near-edge structure (XANES) spectroscopy, and thermogravimetry and differential thermal analysis (TG-DSC). XRD patterns confirmed the formation of samples with the spinel structure. XANES showed the valence and site occupancy of the substituting cations. Cr cations are in the valence of +3 and occupy the octahedral sites. The valences of Mn cation are +2 and +3. Mn2+ and Mn3+ cations preferentially entered the tetrahedral and octahedral sites, respectively. Both Co and Ni cations have a valence of +2 and mainly occupy the octahedral sites. The introduction of Cr and Ni cations obviously increases the amount of superficial hydroxyl groups. The incorporation of Mn, Co and Ni enhances the oxidation temperature of magnetite. All the four kinds of substituting cations in this study increase the temperature of phase transformation from maghemite (?-Fe2O3) to hematite (?-Fe2O3). The mechanism of substitution changing the temperatures of oxidation and phase transformation was also discussed.

  3. Characterization of the temperature- and pressure-induced inverse and reentrant transition of the minimum elastin-like polypeptide GVG(VPGVG) by DSC, PPC, CD, and FT-IR spectroscopy.

    PubMed

    Nicolini, C; Ravindra, R; Ludolph, B; Winter, R

    2004-03-01

    We investigated the temperature- and pressure-dependent structure and phase behavior of a solvated oligopeptide, GVG(VPGVG), which serves as a minimalistic elastin-like model system, over a large region of the thermodynamic phase field, ranging from 2 to 120 degrees C and from ambient pressure up to approximately 10 kbar, applying various spectroscopic (CD, FT-IR) and thermodynamic (DSC, PPC) measurements. We find that this octapeptide behaves as a two-state system which undergoes the well-known inverse-temperature folding transition occurring at T approximately 36 degrees C, and, in addition, a slow trend reversal at higher temperatures, finally leading to a reentrant unfolding close to the boiling point of water. Furthermore, the pressure-dependence of the folding/unfolding transition was studied to yield a more complete picture of the p, T-stability diagram of the system. A molecular-level picture of these processes, in particular on the role of water for the folding and unfolding events of the peptide, presented with the help of molecular-dynamics simulations, is presented in a companion article in this issue. PMID:14990468

  4. Following the growth of surface films on lithium and their thermal behavior in standard LiPF6 solutions using differential scanning calorimetry.

    PubMed

    Larush, Liraz; Zinigrad, Ella; Goffer, Yossi; Aurbach, Doron

    2007-12-18

    In this paper, we report on attempts to use differential scanning calorimetric measurements of aged Li electrodes for the study of the kinetics of the growth of surface films on the active metal. Standard, commonly used alkyl carbonate solutions such as ethylene and di-methyl carbonates with LiPF6 were explored. Heating Li samples in solutions after aging by DSC, resulted in well-resolved curves of reaction heats vs temperature. Exothermic reactions occurring at temperatures below 150 degrees C could be attributed to changes related to the surface films and their heat evolved, increased as a function of storage time, and hence these heats represent the thickness of the surface films that grow upon storage. Scanning electron microscopy of the Li surfaces as a function of storage and heating to different temperatures confirmed that the thermal reactions of Li surfaces in these solutions up to 150 degrees C relate to the surface films only. XPS studies revealed that these processes of the surface films change the metastable organic Li salts to more stable inorganic compounds such as LiF and Li2O. Massive red-ox reactions, between the salt anion and the solvents and between the solution species and the active metal, occur at temperatures higher than 150 degrees C. The kinetics of growth of the surface films on Li show an inverse logarithmic behavior, expected for thin surface films with which the rate-limiting step of their growth depends on ions transport across the film. PMID:18001062

  5. SuperNEMO - the next generation double beta decay experiment

    E-print Network

    Irina Nasteva; for the SuperNEMO collaboration

    2009-09-17

    The SuperNEMO experiment is being designed to search for neutrinoless double beta decay to test if neutrinos are Majorana particles. The experimental technique follows that of the currently running NEMO-3 experiment, which successfully combines tracking and calorimetry to measure the topology and energy of the final state electrons. Unique particle identification capabilities of SuperNEMO will be employed with about 100 kg of 82 Se and will reach sensitivity to a half-life of about 2 x 10^26 years, which corresponds to Majorana neutrino masses of about 50 meV, depending on the calculated value of the nuclear matrix element. In this poster, the current status of the SuperNEMO project is presented.

  6. Field Experiments

    Microsoft Academic Search

    Glenn W. Harrison; John A. List

    2004-01-01

    Experimental economists are leaving the reservation. They are recruiting subjects in the field rather than in the classroom, using field goods rather than induced valuations, and using field context rather than abstract terminology in instructions. We argue that there is something methodologically fundamental behind this trend. Field experiments differ from laboratory experiments in many ways. Although it is tempting to

  7. Herschel Experiment

    NSDL National Science Digital Library

    In this experiment, students replicate a version of the 1800 experiment in which a form of radiation other than visible light was discovered by the famous astronomer Sir Frederick William Herschel. Students use glass prisms, thermometers, and sunlight to detect the increase in temperature beyond the red end of the visible spectrum, thus detecting infrared light.

  8. Crystallisation behaviour of bulk metallic glasses by in-situ neutron diffraction

    NASA Astrophysics Data System (ADS)

    Soubeyroux, J. L.; Claret, N.

    Crystallisation behaviour of some bulk metallic glasses has been studied by neutron diffraction and by differential scanning calorimetry (DSC) performed at the same heating rate. The alloys Zr51Ti2.5Al11.5Cu22Ni13 (F35) and Zr41.25Ti13.75Cu8Ni14.5Be22.5 (Vit1*) present a first crystallisation corresponding to the first peak in the DSC experiments, this first phase being different in each system and corresponding to intermediate phases. The Pd43Cu27Ni10P20 alloy crystallises by forming, in a very narrow interval of temperature, binary and ternary phosphides, all stable up to the melting temperature. The combination of in-situ neutron-diffraction and DSC experiments has proved to be a powerful technique to study the crystallisation of bulk metallic glasses.

  9. TRIO experiment

    SciTech Connect

    Clemmer, R.G.; Finn, P.A.; Malecha, R.F.; Misra, B.; Billone, M.C.; Bowers, D.L.; Fischer, A.K.; Greenwood, L.R.; Mattas, R.F.; Tam, S.W.

    1984-09-01

    The TRIO experiment is a test of in-situ tritium recovery and heat transfer performance of a miniaturized solid breeder blanket assembly. The assembly (capsule) was monitored for temperature and neutron flux profiles during irradiation and a sweep gas flowed through the capsule to an anaytical train wherein the amounts of tritium in its various chemical forms were determined. The capsule was designed to operate at different temperatures and sweep gas conditions. At the end of the experiment the amount of tritium retained in the solid was at a concentration of less than 0.1 wppM. More than 99.9% of tritium generated during the experiment was successfully recovered. The results of the experiment showed that the tritium inventories at the beginning and at the end of the experiment follow a relationship which appears to be characteristic of intragranular diffusion.

  10. DSC Approach to Computational Fluid Dynamics

    E-print Network

    Steffen Hein

    2006-04-01

    This paper presents the Dual Scattering Channel numerical solution of the Navier-Stokes Equations for quasi-incompressible flow in the Oberbeck-Boussinesq approximation. The implementation in hexahedral non-orthogonal mesh is outlined. A numerical example illustrates the approach.

  11. Static and dynamic thermal quantities near the consolute point of the binary liquid mixture aniline-cyclohexane studied with a photopyroelectric technique and adiabatic scanning calorimetry.

    PubMed

    Pittois, S; Van Roie, B; Glorieux, C; Thoen, J

    2005-01-01

    We studied the thermal conductivity, thermal effusivity, and specific heat capacity at constant pressure of the critical binary liquid mixture aniline-cyclohexane near the consolute point, using a photopyroelectric (PPE) technique and adiabatic scanning calorimetry (ASC). According to recent theoretical predictions based on renormalization group theory calculations, a substantial (but not diverging) enhancement in the thermal conductivity in the homogeneous phase near the critical temperature was expected for this binary system near the consolute point. However, within an experimental precision of 0.05%, we found no deviation from linear behavior in the range of 5 K above Tc down to Tc. The specific heat capacity calculated from the results for the thermal conductivity and effusivity is in good agreement with that measured by ASC. For the ASC results, the theoretical power law expression with the Ising critical exponent was fitted to the specific heat capacity both above and below the transition temperature. Good agreement with theory was found both for the amplitude ratio and the two-scale universality. PMID:15638595

  12. Non-isothermal crystallization kinetics and glass-forming ability of Ti41Zr25Be28Fe6 bulk metallic glass investigated by differential scanning calorimetry

    NASA Astrophysics Data System (ADS)

    Gong, Pan; Zhao, Shaofan; Wang, Xin; Yao, Kefu

    2015-07-01

    The non-isothermal crystallization kinetics and glass-forming ability of Ti41Zr25Be28Fe6 glassy alloy were investigated by differential scanning calorimetry. The activation energies corresponding to the characteristic temperatures have been calculated by Kissinger and Ozawa equations. Based on Kissinger-Akahira-Sunose and Ozawa-Flynn-Wall models, it has been found that the local activation energy is higher at the beginning of the crystallization process for the first exothermic peak. The local Avrami exponent indicates that the first-step crystallization is mainly a high-dimensional nucleation and growth with an increasing nucleation rate. According to the calculated fragility index, Ti41Zr25Be28Fe6 alloy can be classified as "strong glass former." The studied alloy also possesses a critical size up to centimeter order, and the high glass-forming ability is probably related to the relatively low Gibbs energy difference between the liquid and crystalline states. The critical cooling rate of Ti41Zr25Be28Fe6 glassy alloy has also been determined using Barandiaran-Colmenero's method.

  13. The association of octadecyl-end-capped poly-(sodium 2-acrylamido-2-methylpropanesulfonates) in water and salt solutions: A study by fluorescence spectroscopy and isothermal titration calorimetry

    NASA Astrophysics Data System (ADS)

    Mizusaki, M.; Morishima, Y.; Raju, B. B.; Winnik, F. M.

    Steady-state fluorescence spectroscopy and isothermal titration calorimetry (ITC) have been used to study the aggregation in aqueous solutions of poly-(2-acrylamido)-2-methylpropanesulfonic acids, sodium salt mono-endcapped with either N,N-di-n-octadecyl or N-4-[(1-pyrenyl)butyl]-N-n-octadecyl which were prepared by free radical polymerization of 2-(acrylamido)-2-methylpropane sulfonic acid (AMPS) initiated with the azo compounds, 4,4'-azobis{cyano-N,N-di-n-octadecyl}pentanamide and 4,4'-azobis{cyano-N,N-[4-(1-pyrenyl)butyl]-n-octadecyl}pentanamide, respectively. Both techniques indicate the occurrence of multimolecular aggregates in solutions of the polymers in water and in 0.2 M NaCl. The concentration range for aggregation is about 1-14 mmol AMPS l^{-1} (0.5-2.7 g l^{-1}) in 0.2 M NaCl and the enthalpy of micellization, estimated from ITC data, is 100 J [mol AMPS]^{-1}. The accessibility of the chromophores to neutral molecules and to cationic species was assessed by quenching of fluorescence with nitromethane and thallium nitrate, respectively. The association of the mono-endcapped polymers is compared to that of PAMPS derivatives carrying hydrophobic groups randomly attached along the chain.

  14. Standard enthalpies of formation of neodymium alloys, Nd + Me (Me ? Ni, Ru, Rh, Pd, Ir, Pt), by high-temperature direct synthesis calorimetry

    NASA Astrophysics Data System (ADS)

    Guo, Qiti; Kleppa, O. J.

    1995-04-01

    The Standard enthalpies of formation of 14 neodymium alloys have been determined by direct synthesis calorimetry at 1477 ± 2 K. The following values of ?H{f/o}(kJ/g atom) are reported: NdNi5, -(26.2 ± 1.1); Nd5Ru2, -(17.2 ± 1.9); NdRu2, -(18.8 ± 1.2); Nd5Rh4, -(59.9 ± 2.5); NdRh, -(64.2 ± 2.0); NdRh2, -(59.9 ± 1.1); NdRh3, -(44.4 ± 1.6); NdPd, -(77.2 ± 2.7); NdPd3, -(73.3 ± 2.3); Nd5Ir3, -(59.7 ± 2.7); NdIr2, -(67.6 ± 1.5); NdPt, -(104.4 ± 2.6); NdPt2, -(97.9 ± 2.4); and NdP5, -(55.0 ± 3.1). The results are compared with available literature data for some of the neodymium alloys and with predicted values from the Miedema model.

  15. Calorimetry of silicate melts at 1773 K: measurement of enthalpies of fusion and of mixing in the systems diopside-anorthite-albite and anorthite-forsterite

    NASA Astrophysics Data System (ADS)

    Navrotsky, Alexandra; Ziegler, David; Oestrike, Richard; Maniar, Papu

    1989-01-01

    Transposed-temperature-drop calorimetry, using a Setaram HT 1500 calorimeter, was used to study directly the melting at 1773 K of mixtures of crystalline albite, anorthite, and diopside and of anorthite and forsterite. The enthalpy of albite at 1000 1773 K, starting with both crystalline and glassy samples, was also measured. The results confirm previously measured enthalpies of fusion of albite, diopside and anorthite (Stebbins et al. 1982, 1983; Richet and Bottinga 1984,1986). The new results use thermochemical cycles which completely avoid the glassy state by transforming crystals directly to melts. The enthalpy of fusion of forsterite is estimated to be 89±12 kJ/mol at 1773 K and 114±20 kJ/mol at its melting point of 2163 K. The data allow semiquantitative evaluation of heats of mixing in the molten silicates. Along the Ab-An join, enthalpies of mixing in the liquid at 773 K are the same or somewhat more negative than those in the glass at 986 K, whereas along Ab-Di and An-Di, enthalpies of mixing in the liquid are distinctly more positive than in the glass. These differences correlate with excess heat capacities in the liquids suggested by Stebbins et al. (1984).

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

    PubMed

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

    2014-12-01

    A model molecular biosystem of hydrated dipalmitoylphosphatidylcholine (DPPC) bilayers that mimics cell biomembranes is used to probe combined membranotropic effects of drugs by instrumental techniques of molecular biophysics. Differential scanning calorimetry reveals that doping of the DPPC model membrane with individual bisquaternary ammonium compounds (BQAC) decamethoxinum, ethonium, thionium and acetylsalicylic acid (ASA) leads to lowering of the membrane melting temperature (Tm) pointing to membrane fluidization. Combined application of the basic BQAC and acidic ASA causes an opposite effect on Tm (increase), corresponding to the membrane densification. Thus, modulation of the membranotropic effects upon combined use of the drugs studied can be revealed at the level of model membranes. Formation of noncovalent supramolecular complexes of the individual BQACs and ASA with DPPC molecules, which may be involved in the mechanism of the drug-membrane interaction at the molecular level, is demonstrated by electrospray ionization (ESI) mass spectrometry. In the ternary (DPPC + ASA + BQAC) model systems, the stable complexes of the BQAC dication with the ASA anion, which may be responsible for modulation of the membranotropic effects of the drugs, were recorded by ESI mass spectrometry. The proposed approach can be further developed for preliminary evaluation of the combined effects of the drugs at the level of model lipid membranes prior to tests on living organisms. PMID:25233235

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

    PubMed

    Choudhary, Sinjan; Talele, Paurnima; Kishore, Nand

    2015-08-01

    The success of drug delivery depends on the efficiency of the route of administration, which in turn relies on properties of the drug and its transport vehicle. A quantitative knowledge of association of drugs with transport vehicles is lacking when the latter are in the category of self assembled structures. The work reported in this manuscript addresses the mechanism of partitioning of naproxen, diclofenac sodium, neomycin and lincomycin in the micelles of hexadecytrimethylammonium bromide and that is quantitatively based on the measurement of thermodynamic parameters of interactions by using isothermal titration calorimetry. The addressed mechanism of partitioning is based on the identification of the type of interactions of these drugs with the surfactant micelles and monomers, along with the effect of the former on the micellization properties of the surfactant. The conclusions are based on the interpretation of the values of partitioning constant, standard molar enthalpy change, standard molar entropy change and the stoichiometry of the interaction. The results of this study have implications for deriving guidelines for the target oriented synthesis of new drugs that are to be used for effective delivery via micellar media. PMID:26057731

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

    PubMed

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

    2015-09-01

    The aggregation number (n), thermodynamic potentials (?G, ?H, ?S) and critical micelle concentration (CMC) for 6 natural bile salts were determined on the basis of both original and previously published isothermal titration calorimetry (ITC) data. Different procedures to estimate parameters of micelles with ITC were compared to a mass-action model (MAM) of reaction type: n?S?Mn. This analysis can provide guidelines for future ITC studies of systems behaving in accordance with this model such as micelles and proteins that undergo self-association to oligomers. Micelles with small aggregation numbers, as those of bile salts, are interesting because such small aggregates cannot be characterized as a separate macroscopic phase and the widely applied pseudo-phase model (PPM) is inaccurate. In the present work it was demonstrated that the aggregation number of micelles was constant at low concentrations enabling determination of the thermodynamic potentials by the MAM. A correlation between the aggregation number and the heat capacity was found, which implies that the dehydrated surface area of bile salts increases with the aggregation number. This is in accordance with Tanford's principles of opposing forces where neighbouring molecules in the aggregate are better able to shield from the surrounding hydrophilic environment when the aggregation number increases. PMID:25978555

  19. Non-isothermal crystallization kinetics and glass-forming ability of Ti41Zr25Be28Fe6 bulk metallic glass investigated by differential scanning calorimetry

    NASA Astrophysics Data System (ADS)

    Gong, Pan; Zhao, Shaofan; Wang, Xin; Yao, Kefu

    2015-04-01

    The non-isothermal crystallization kinetics and glass-forming ability of Ti41Zr25Be28Fe6 glassy alloy were investigated by differential scanning calorimetry. The activation energies corresponding to the characteristic temperatures have been calculated by Kissinger and Ozawa equations. Based on Kissinger-Akahira-Sunose and Ozawa-Flynn-Wall models, it has been found that the local activation energy is higher at the beginning of the crystallization process for the first exothermic peak. The local Avrami exponent indicates that the first-step crystallization is mainly a high-dimensional nucleation and growth with an increasing nucleation rate. According to the calculated fragility index, Ti41Zr25Be28Fe6 alloy can be classified as "strong glass former." The studied alloy also possesses a critical size up to centimeter order, and the high glass-forming ability is probably related to the relatively low Gibbs energy difference between the liquid and crystalline states. The critical cooling rate of Ti41Zr25Be28Fe6 glassy alloy has also been determined using Barandiaran-Colmenero's method.

  20. experiment, collaboration

    E-print Network

    -Departamento Energias Renovables, Plataforma Solar de Almeria, E-04080 Almeria, Spain Departamento de Lenguajes y; 5 Rainer Plaga The GRAAL experiment, ECRS Lodz July 2000 Location of GRAAL " Plataforma Solar de

  1. Poker Experiment

    NSDL National Science Digital Library

    Kyle Siegrist

    This resource consists of a Java applet and expository text. The applet simulates the basic poker experiment of dealing 5 cards from a standard deck. The random variable of interest is the type of hand.

  2. Control experiment

    NSDL National Science Digital Library

    Peggy Greb (USDA; ARS)

    2006-05-23

    There is a type of experiment in which a scientist uses a control variable approach. All conditions in the experiment will be the same except for one variable. When testing water tolerance of barley plants, for example, you could not water one plant, over-water one plant, under-water another plant, and water the last plant with the optimal amount of water and observe the results.

  3. Experiment Databases

    NASA Astrophysics Data System (ADS)

    Vanschoren, Joaquin; Blockeel, Hendrik

    Next to running machine learning algorithms based on inductive queries, much can be learned by immediately querying the combined results of many prior studies. Indeed, all around the globe, thousands of machine learning experiments are being executed on a daily basis, generating a constant stream of empirical information on machine learning techniques. While the information contained in these experiments might have many uses beyond their original intent, results are typically described very concisely in papers and discarded afterwards. If we properly store and organize these results in central databases, they can be immediately reused for further analysis, thus boosting future research. In this chapter, we propose the use of experiment databases: databases designed to collect all the necessary details of these experiments, and to intelligently organize them in online repositories to enable fast and thorough analysis of a myriad of collected results. They constitute an additional, queriable source of empirical meta-data based on principled descriptions of algorithm executions, without reimplementing the algorithms in an inductive database. As such, they engender a very dynamic, collaborative approach to experimentation, in which experiments can be freely shared, linked together, and immediately reused by researchers all over the world. They can be set up for personal use, to share results within a lab or to create open, community-wide repositories. Here, we provide a high-level overview of their design, and use an existing experiment database to answer various interesting research questions about machine learning algorithms and to verify a number of recent studies.

  4. Heat capacity of the reference material synthetic sapphire (?-Al 2O 3) at temperatures from 298.15 K to 1000 K by adiabatic calorimetry. Increased accuracy and precision through improved instrumentation and computer control

    Microsoft Academic Search

    Svein Stølen; Ronny Glöckner; Fredrik Grønvold

    1996-01-01

    The heat capacity of synthetic sapphire is determined by adiabatic shield calorimetry at temperatures from 298.15 K to 1000 K. The calorimetric procedures are discussed in detail. Special attention is given to temperature calibration, and to transformation of temperatures measured on IPTS-48 and IPTS-68 to ITS-90. The accuracy of the present temperature determination is considered to be within 0.02 K

  5. Characterization of double walled carbon nanotubes-polyvinylidene fluoride nanocomposites 

    E-print Network

    Almasri, Atheer Mohammad

    2007-04-25

    and Transmission Electron Microscopy................... 43 2.3. Electrical and Dielectric Spectroscopy.................................................. 43 2.4. Differential Scanning Calorimetry (DSC... 3.2. Percolation and Dielectric Spectroscopy................................................ 58 3.3. Differential Scanning Calorimetry (DSC).............................................. 68 3.4. Wide Angle X...

  6. Understanding the differential thermal behaviour of an oriented polymeric film, in response to the modulated differential scanning calorimetry variables, for determination of the degree of crystallinity

    NASA Astrophysics Data System (ADS)

    Ambardekar, Rohan; Karandikar, Hrushikesh; Kelly, Adrian; Caton-Rose, Phil; Coates, Phil; Paradkar, Anant

    2015-05-01

    The degree and the nature of crystallinity determine several key properties of an oriented polymeric system. Thermal analysis, although widely used for crystallinity determination, may have limited precision with oriented polymers, due to the differential nature and overlap of multiple thermal events (cold-crystallisation, chain-relaxation, etc). In this paper we have studied, how MDSC (Modulated Differential Scanning Calorimetry) variables manipulate the thermal behaviour of oriented materials, so that the degree and the nature of crystallisation can be well defined. MDSC curves suggested that the thermal events were significantly shaped by the amplitude (?) and the period (?) of thermal modulations. Anisotropic thermal conductivity of the oriented PLA film lead to generation of an error in the calculation of non-reversible signal, seen as an artefact in the crystallisation exotherm. Higher amplitude increased the sensitivity of the method. However, when the rise in the amplitude lead to a shift from a `heat-only' to a `heat-cool-heat' cycle, contribution from a poor baseline resulted in the low estimate of the crystallinity. For the `heat-only' cycles, measured crystallinity decreased inversely with the heating rate and ?, due to time dependent crystallisation and melting. Heat-cool-heat cycles lead to crystallisation of some part of the polymer in a more perfected crystal form, whose melting was visible as a non-reversible event. The observations suggested that the heat-only cycles with longer period and faster heating rates favour estimation of the crystallinity, whereas heat-cool-heat cycles with higher amplitude help in understanding pre-melting thermal events associated with polymer orientation. A clear understanding of such an effect is necessary to establish the suitability of MDSC in rapid estimation of crystallinity of the oriented polymers. Accuracy of the method was evaluated by studying the films oriented to different draw ratios and comparison to other established methods. However, this part is not included in this brief communication.

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  8. Probing the interaction of lysozyme with ciprofloxacin in the presence of different-sized Ag nano-particles by multispectroscopic techniques and isothermal titration calorimetry.

    PubMed

    Pasban Ziyarat, Fatemeh; Asoodeh, Ahmad; Sharif Barfeh, Zahra; Pirouzi, Maliheh; Chamani, Jamshidkhan

    2014-04-01

    The binding of ciprofloxacin to lysozyme in the presence of three Ag nano-particles of varying sizes was for the first time investigated by multispectroscopic and isothermal titration calorimetry techniques at pH 7.4. The results indicated that ciprofloxacin quenched the fluorescence intensity of lysozyme through a static mechanism but in the presence of size-II Ag nano-particles, there were two kinds of interaction behaviors. The interaction between ciprofloxacin and lysozyme occurred via a second type of binding site, whereas in the presence of the Ag nano-particles, some changes occurred. The secondary structure of lysozyme-ciprofloxacin in the presence of Ag nano-particles was determined by circular dichroism. The thermodynamic parameters of the interaction between ciprofloxacin and lysozyme in the presence of Ag nano-particles were measured according to the van't Hoff equation. The enthalpy (?H(?)) and entropy (?S(?)) changes were calculated to be -49.7 (kJ?mol(-1)) and -20.1 (J?mol(-1)?K(-1)), respectively, which indicated that the interaction of ciprofloxacin with lysozyme was driven mainly by van der Waals forces and hydrogen bonding. In the presence of the three different-sized Ag nano-particles, the enthalpic and the entropic changes were both negative which indicated that hydrogen bonding with van der Waals forces played major roles in the binding between ciprofloxacin and lysozyme. Recent developments in nano-materials offer new pathways for controlling the protein behavior through surface interactions. These data indicate that the recent research on nano-particle/protein interactions will emphasize the importance of such interactions in biological systems with applications including the diagnosis and treatment of human diseases. PMID:23659247

  9. A short period of fasting before surgery conserves basal metabolism and suppresses catabolism according to indirect calorimetry performed under general anesthesia.

    PubMed

    Yoshimura, Shinichiro; Fujita, Yoshihito; Hirate, Hiroyuki; Kusama, Nobuyoshi; Azami, Takafumi; Sobue, Kazuya

    2015-06-01

    It is recommended that the period of fasting before elective surgery should be shortened to facilitate a rapid recovery by preventing catabolism. We examined the effects of a short period of fasting on metabolism by performing indirect calorimetry (IC) under general anesthesia. A prospective observational study involving 26 consecutive patients who underwent elective surgery and whose metabolism was evaluated using IC during anesthesia was conducted. The patients were divided into two groups, those who fasted for <8 h (group S) and those who fasted for >10 h (group L). Oxygen consumption, the volume of carbon dioxide emissions (VCO2), the respiratory quotient (RQ), resting energy expenditure (REE), and basal energy expenditure (BEE) were compared. The REE, VCO2, and RQ of group L (17.7 ± 2.3 kcal/kg/day, 118.5 ± 20.8 ml/min, and 0.71 ± 0.12, respectively) were significantly lower than those of group S (19.7 ± 2.3 kcal/kg/day, 143.6 ± 30.9 ml/min, and 0.81 ± 0.09, respectively) (P < 0.05). In group L, the relationship between REE and BEE was weaker (r (2) = 0.501) and the BEE-REE slope was less steep (REE = 0.419BEE + 509.477) than those seen in group S (r (2) = 0.749 and REE = 1.113BEE - 376.111, respectively). Our findings suggest that a short period of fasting (<8 h) before surgery is more strongly associated with the conservation of basal metabolism. PMID:25398400

  10. The net energy values of corn, dried distillers grains with solubles and wheat bran for laying hens using indirect calorimetry method.

    PubMed

    Ning, D; Yuan, J M; Wang, Y W; Peng, Y Z; Guo, Y M

    2014-02-01

    The present study was conducted to estimate the NE values of corn, dried distillers grains with solubles (DDGS) and wheat bran (WB) for laying hens based on an indirect calorimetry method and nitrogen balance measurements. A total of 576 twenty-eight-wk-old Dwarf Pink-shell laying hens were randomly assigned to four groups fed a basal diet (BD) or a combination of BD with 50% corn or 20% DDGS or 20% WB, with four replicates each. After a 7-d adaptation period, each replicate with 36 hens were kept in one of the two respiration chambers to measure the heat production (HP) for 6 days during the feeding period and subsequent 3-d fasting. The equilibrium fasting HP (FHP) provided an estimate of NE requirements for maintenance (NEm). The NE values of test feedstuffs was estimated using the difference method. Results showed that the heat increment that contributed 35.34 to 37.85% of ME intake was not influenced by experimental diets (p>0.05) when expressed as Mcal/kg of DM feed intake. Lighting increased the HP in hens in an fed-state. The FHP decreased over time (p<0.05) with the lowest value determined on the third day of starvation. No significant difference between treatments was found on FHP of d 3 (p>0.05). The estimated AME, AMEn, and NE values were 3.46, 3.44 and 2.25 Mcal/kg DM for corn, 3.11, 2.79, and 1.80 Mcal/kg DM for DDGS, 2.14, 2.10, and 1.14 Mcal/kg DM for WB, respectively. The net availability of AME of corn tended to be numerically higher than DDGS and WB (p = 0.096). In conclusion, compared with corn, the energy values of DDGS and WB were overestimated when expressed on an AME basis. PMID:25049945

  11. SANE experiment

    NASA Astrophysics Data System (ADS)

    Baghdasaryan, H.; SANE Collaboration

    2012-02-01

    The Spin Asymmetries of the Nucleon Experiment (SANE) is a measurement of parallel and near-perpendicular double spin asymmetries in an inclusive electron scattering. The main goal of the experiment was to measure A? and A80 and extract the spin asymmetries of the proton Ap1, Ap2 and spin structure functions gp1 and gp2. Using the Thomas Jefferson National Accelerator Facility's polarized electron beam and the University of Virginia's polarized frozen ammonia (14NH3) target in Hall C, the experiment ran in 2009, collecting data in a Q2 region from 2.5 to 6.5 GeV2 and between Bjorken x of 0.3 to 0.8. Particle detection was accomplished using the Big Electron Telescope Array (BETA), a novel non-magnetic detector. This talk will address the progress of the analysis designed to extract the proton spin asymmetries and structure functions. Preliminary results will be presented.

  12. Rutherford Experiment

    NSDL National Science Digital Library

    Wolfgang Christian

    The simulation below shows an interaction between two "particles." The interaction force is a 1/r2 force; that is, the interaction force varies as 1/r2 where r is the distance between them. However, it only "exists" when the particles are less than 0.2 m apart. This collision is similar to the type of collisions that occurred between alpha particles and gold nuclei in the famous Rutherford experiment. This experiment showed that the very massive nuclei is very small compared to the size of the atom.

  13. Digestion Experiments

    E-print Network

    Fraps, G. S. (George Stronach)

    1908-01-01

    , Pennsylvania Experi- ment Station.) The productive values of feeding stuffs and the nutrients which com- pose them have been measured in terms of fat by Kellner. The method of experiment consists in feeding the animal with a basal ration which is more than... approximately one-third was ash, sorrlcthing over one-third was protein, and less than one-third non- protein organic matter. .About 10 per cent of the total protein, 20 per cent of the total ash, and 3 per cent of the nitrogen-free ext solul~le in water...

  14. TRIO experiment

    Microsoft Academic Search

    R. G. Clemmer; P. A. Finn; R. F. Malecha; B. Misra; M. C. Billone; D. L. Bowers; A. K. Fischer; L. R. Greenwood; R. F. Mattas; S. W. Tam

    1984-01-01

    The TRIO experiment is a test of in-situ tritium recovery and heat transfer performance of a miniaturized solid breeder blanket assembly. The assembly (capsule) was monitored for temperature and neutron flux profiles during irradiation and a sweep gas flowed through the capsule to an anaytical train wherein the amounts of tritium in its various chemical forms were determined. The capsule

  15. Ballot Experiment

    NSDL National Science Digital Library

    Kyle Siegrist

    This resource consists of a Java applet and expository text. The applet is a simulation of the ballot experiment: The votes in an election are randomly counted. The event of interest is that the winning candidate is always ahead in the vote count.

  16. Triangle Experiment

    NSDL National Science Digital Library

    Kyle Siegrist

    This resource consists of a Java applet and expository text. The applet llustrates the triangle experiment: A stick is broken randomly into three parts. The events of interest are that the pieces form an acute triangle, an obtuse triangle, or no triangle.

  17. Birthday Experiment

    NSDL National Science Digital Library

    Kyle Siegrist

    This resource consists of a Java applet and expository text. The applet is a simulation of the birthday experiment: a sample of size n is chose at random and with replacement from the first m positive integers. The random variable of interest is the number of distinct sample values. The event of interest is that all sample values are distinct.

  18. Bertrand's Experiment

    NSDL National Science Digital Library

    Kyle Siegrist

    This resource consists of a Java applet and expository text. The applet is a simulation of Bertrand's experiment: a random chord on a cirle. The event of interest is whether the length of the chord is larger than the length of the inscribed equilateral triangle. Three models for generating the random chord can be used.

  19. Biodiesel Experiment

    NSDL National Science Digital Library

    Lawrence, Richard

    The Advanced Technology Environmental and Energy Center (ATEEC) provides this classroom activity on biodiesel. The experiment involves using some chemicals which may be considered extremely dangerous; educators should be sure to practice laboratory safety when using this lesson. Users must download this resource for viewing, which requires a free log-in. There is no cost to download the item.

  20. Calorimetry of epitaxial thin films

    SciTech Connect

    Cooke, David W.; Hellman, F. [Department of Physics, University of California at Berkeley, Berkeley, California 94720-7300 (United States); Groves, J. R.; Clemens, B. M. [Department of Materials Science, Stanford University, Stanford, California 94305 (United States); Moyerman, S.; Fullerton, E. E. [Center for Magnetic Recording Research, University of California at San Diego, La Jolla, California 92093-0401 (United States)

    2011-02-15

    Thin film growth allows for the manipulation of material on the nanoscale, making possible the creation of metastable phases not seen in the bulk. Heat capacity provides a direct way of measuring thermodynamic properties of these new materials, but traditional bulk calorimetric techniques are inappropriate for such a small amount of material. Microcalorimetry and nanocalorimetry techniques exist for the measurements of thin films but rely on an amorphous membrane platform, limiting the types of films which can be measured. In the current work, ion-beam-assisted deposition is used to provide a biaxially oriented MgO template on a suspended membrane microcalorimeter in order to measure the specific heat of epitaxial thin films. Synchrotron x-ray diffraction showed the biaxial order of the MgO template. X-ray diffraction was also used to prove the high quality of epitaxy of a film grown onto this MgO template. The contribution of the MgO layer to the total heat capacity was measured to be just 6.5% of the total addenda contribution. The heat capacity of a Fe{sub .49}Rh{sub .51} film grown epitaxially onto the device was measured, comparing favorably to literature data on bulk crystals. This shows the viability of the MgO/SiN{sub x}-membrane-based microcalorimeter as a way of measuring the thermodynamic properties of epitaxial thin films.