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1

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

National Technical Information Service (NTIS)

The technique of Differential Scanning Calorimetry (DSC) has been applied to the characterization and the analysis of several activated carbons. These activated carbons included BPL carbon (a base carbon), ASC carbon (a BPL carbon impregnated with copper,...

L. E. Cameron S. H. Liang

1991-01-01

2

Differential Scanning Calorimetry (DSC) for planetary surface exploration  

NASA Technical Reports Server (NTRS)

Differential Scanning Calorimetry (DSC) is the quantitative measurement of the enthalpic response of a material to a systematic change in temperature. In practice, the heat flow into or outward from a sample is measured as the sample is heated or cooled at a carefully controlled rate. DSC superficially resembles, but is not the same as differential thermal analysis (DTA), which is the measurement of temperature differences between a sample and reference material as the pair is heated or cooled. The fundamental properties measured by DSC are enthalpies and temperatures of phase transitions and constant-pressure heat capacities. Depending on instrument design and the nature of the sample, high-quality DSC analyses can be obtained on only a few milligrams of solid materials. DSC requires direct contact with the sample and generally degrades, if not destroys, the sample as a consequence of heating. In laboratory applications, it is common to subject the gaseous effluent from the DSC to analysis by a separate evolved-gas analyzer (EGA).

Gooding, James L.; Ming, Douglas W.

1993-01-01

3

Determination of Purity by Differential Scanning Calorimetry (DSC).  

ERIC Educational Resources Information Center

An exercise is presented which demonstrates the determination of sample purity by differential scanning calorimetry. Data and references are provided to enable the exercise to be carried out as a dry-lab experiment. (BB)

Brown, M. E.

1979-01-01

4

Thermomechanical analysis (TMA) correlated to differential scanning calorimetry (DSC) for ageing study of some metallic glasses  

Microsoft Academic Search

To characterize the ageing of some metallic glasses, a correlated study of the differential scanning calorimetry method (DSC) and of the thermomechanical analysis (TMA) emphasizes the specificity of the latter. We analyzed metallic glasses which have been produced either by chemical methods or by melt spinning techniques. Using TMA and DSC, we have established that the relaxation of metallic glasses

F. A. Kuhnast

1992-01-01

5

Wheat Flour and Defatted Milk Fractions Characterized by Differential Scanning Calorimetry. I. DSC of Flour and Milk Fractions  

Microsoft Academic Search

Cereal Chem. 72(l):70-75 Differential scanning calorimetry (DSC) thermograms were determined starches due to the competition for available water. Laboratory-prepared for wheat flour and milk fractions. Compositional and structural differ- acid whey showed higher denaturation temperatures than sweet whey, ences between prime and tailings starch apparently affected their DSC which is explained by the acid-resistant character of the major whey protein

N. ERDOGDU; Z. CZUCHAJOWSKA; Y. POMERANZ

6

A new simultaneous apparatus for X-ray diffractometry and differential scanning calorimetry (XRD-DSC)  

Microsoft Academic Search

An instrument was developed for performing simultaneous X-ray diffractometric and differential scanning calorimetric (XRD-DSC) measurement using a power compensation DSC (pc-DSC). The feasibility of the technique is demonstrated by examining the thermal dehydration measurement of zinc formate dihydrate (Zn(HCO2)2·2H2O). The DSC curve shows apparent double endothermic peaks during the dehydration process, while X-ray diffraction analysis indicated that the resulting anhydrous

Tadashi Arii; Akira Kishi; Yuji Kobayashi

1999-01-01

7

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

Microsoft Academic Search

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

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

2012-01-01

8

Increased corneal hydration induced by potential ocular penetration enhancers: assessment by differential scanning calorimetry (DSC) and by desiccation.  

PubMed

The corneal toxicity of some surfactants of possible use as ocular penetration enhancers was investigated by measuring their effect on hydration of rabbit corneas 'in vitro'. The tested substances were benzalkonium chloride (BAC), cetylpyridinium chloride (CPC), ethylenediaminetetraacetic acid disodium salt (EDTA), polyoxyethylene-20-stearyl ether (Brij 78, PSE), polyethoxylated castor oil (Cremophor EL, PCO) and sodium deoxycholate (DC). Freshly excised corneas, mounted in perfusion cells, were kept in contact for 1 h with solutions of these agents; corneal hydration was then evaluated by measuring: (a) their total (free+bound) water content by desiccation (gravimetric analysis); and (b) their free water content by differential scanning calorimetry (DSC). The DSC measurements also provided a rough quantitative estimate of corneal solutes. All tested agents significantly influenced corneal hydration, evidently as a consequence of alteration of the corneal epithelium. Although a brief contact with the precorneal tissues 'in vivo' may not prove harmful, the use of these compounds as potential ocular permeation enhancers or otherwise as ingredients of topical ocular formulations for long-term use should be considered with caution. PMID:11790497

Monti, D; Chetoni, P; Burgalassi, S; Najarro, M; Saettone, M F

2002-01-31

9

Calorimetry  

NSDL National Science Digital Library

As part of a larger collection of virtual experiments, this link deals exclusively with the fundamentals of Heat Capacity. A bomb calorimeter is shown and the user is allowed to used a desired amount of materials to measure the heat capacity of: 1) ethanol; 2) copper; and 3) ammonium nitrate. Heat of neutralization reactions and combustion reactions are also explored. Nonideal loss and gain of heat during calorimetry experiments are explored by measuring the heat of solution of sulfuric acid. Strategies are also discussed for studying systems in which two chemical reactions simultaneously occur.

Blauch, David N.

10

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

SciTech Connect

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

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

1983-01-01

11

Solution Calorimetry Experiments for Physical Chemistry.  

ERIC Educational Resources Information Center

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)

Raizen, Deborah A.; And Others

1988-01-01

12

Differential Scanning Calorimetry Techniques: Applications in Biology and Nanoscience  

PubMed Central

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.

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

2010-01-01

13

Correlating DSC and X-Ray Measurements Of Crystallinity  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

14

DSC sample preparation for Al-based alloys  

SciTech Connect

Differential Scanning Calorimetry (DSC) is a useful technique for the study of phase transformations and has been widely applied to study precipitation in aluminium alloys. In the present work the effect of sample preparation during DSC heating of a monolithic 8090 (Al-Cu-Mg-Li-Zr) alloy and an 8090 MMC is investigated. The 8090 alloy system seems especially suited for such a study since the main precipitation reactions which occur in this alloy (GPB-zone, {delta}{prime}(Al{sub 3}Li) and S{prime}(Al{sub 2}CuMg) formation) cover a wide range of different types of precipitation reactions. DSC experiments were performed with a Shimadzu DSC-50 employing a nitrogen gas flow using a heating rate of 10 C/min. DSC curves were corrected for the baseline of the DSC and for heat capacity of the alloys following a procedure outlined elsewhere. Hence, the presented DSC curves represent heat flows due to reactions only.

Starink, M.J.; Hobson, A.J.; Gregson, P.J. [Univ. of Southampton (United Kingdom). Dept. of Engineering Materials] [Univ. of Southampton (United Kingdom). Dept. of Engineering Materials

1996-06-01

15

Simultaneous TG/DSC (Thermogravimetry/Differential Scanning Calorimetry) and TG/MS (Thermogravimetry/Mass Spectrometry) Analyses of Polymeric and Energetic Materials.  

National Technical Information Service (NTIS)

The utility of simultaneous thermal analysis techniques, such as TG/DSC and TG/MS, has been demonstrated for both energetic and polymeric materials. TG/DSC can assist in elucidating reaction mechanisms and determining weight losses for endothermic transit...

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

1987-01-01

16

Identifying Hydrated Salts Using Simultaneous Thermogravimetric Analysis and Differential Scanning Calorimetry  

ERIC Educational Resources Information Center

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…

Harris, Jerry D.; Rusch, Aaron W.

2013-01-01

17

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.

18

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

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

19

A quantitative interpretation of DSC experiments on quenched and aged SiC{sub P} reinforced 8090 alloys  

SciTech Connect

Differential Scanning Calorimetry (DSC) is a useful technique for the study of phase transformations and has been widely applied to study precipitation in aluminum alloys, but the results are generally interpreted qualitatively. In the present paper a quantitative interpretation of DSC heat effects occurring in 8090 alloys with and without SiC particle reinforcement is presented. Hardening of 8090 alloys (nominal composition Al-1.3wt% Cu-1wt%Mg-2.5wt%Li) is generally interpreted in terms of two precipitation sequences: (1) Li in Al-rich phase {yields} {delta}{prime} {yields} {delta}, where {delta}{prime} is a L1{sub 2} ordered phase (Al{sub 3}Li), fully coherent with the Al matrix, and {delta} is the equilibrium Al-Li phase (AlLi), which forms mainly at grain boundaries; (2) Cu,Mg in Al-rich phase {yields} GPB zones {yields} S{prime} {yields} S, where GPB zones are Cu and Mg containing Guinier-Preston zones, and S{prime} is a slightly strained semicoherent version of the incoherent S (Al{sub 2}CuMg). Since the formation enthalpies of the two variants are the same, S{prime} and S will be considered to be the same phase in this paper.

Starink, M.J.; Gregson, P.J. [Univ. of Southampton (United Kingdom). Dept. of Engineering Materials] [Univ. of Southampton (United Kingdom). Dept. of Engineering Materials

1995-09-15

20

Effect of milling on DSC thermogram of excipient adipic acid.  

PubMed

The purpose of this research was to investigate why and how mechanical milling results in an unexpected shift in differential scanning calorimetry (DSC) measured fusion enthalpy (Delta(fus)H) and melting point (T(m)) of adipic acid, a pharmaceutical excipient. Hyper differential scanning calorimetry (hyper-DSC) was used to characterize adipic acid before and after ball-milling. An experimental study was conducted to evaluate previous postulations such as electrostatic charging using the Faraday cage method, crystallinity loss using powder X-ray diffraction (PXRD), thermal annealing using DSC, impurities removal using thermal gravimetric analysis (TGA) and Karl Fischer titration. DSC thermograms showed that after milling, the values of Delta(fus)H and T(m) were increased by approximately 9% and 5 K, respectively. Previous suggestions of increased electrostatic attraction, change in particle size distribution, and thermal annealing during measurements did not explain the differences. Instead, theoretical analysis and experimental findings suggested that the residual solvent (water) plays a key role. Water entrapped as inclusions inside adipic acid during solution crystallization was partially evaporated by localized heating at the cleaved surfaces during milling. The correlation between the removal of water and melting properties measured was shown via drying and crystallization experiments. These findings show that milling can reduce residual solvent content and causes a shift in DSC results. PMID:20101483

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

2010-03-01

21

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

SciTech Connect

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.

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

1989-01-01

22

Characterization of polyanhydride microsphere degradation by DSC  

Microsoft Academic Search

Microspheres (2.91?m diameter) were formed from poly(fumaric-co-sebacic anhydride) (P(FASA)) using a phase inversion microencapsulation technique. Blank microspheres, protein-loaded microspheres, and raw polymer were degraded in water for varying lengths of time to determine how degradation affects morphology and crystallinity. The rate of degradation was subsequently characterized using differential scanning calorimetry (DSC) and step-scan alternating DSC (SSADSC). As evident by the

M. Sandor; N. A. Bailey; E. Mathiowitz

2002-01-01

23

Hadron Calorimetry  

NASA Astrophysics Data System (ADS)

Hadron calorimetry has been a rapidly developing field in the past few decades. Perhaps not too far in the future, a realistic calorimeter will be capable of measuring the energies of all the fundamental particles with ˜1% precision. Currently, calorimeters with unprecedented complexity attest to the knowledge and experience that have been accumulated in high energy physics. In this review, we touch on fundamental concepts and explain new developments that we expect to be important in the future. In addition to describing applications in accelerator-based high energy physics, we briefly mention the use of hadron calorimeters in other fields.

Akchurin, Nural; Wigmans, Richard

2012-02-01

24

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

NASA Astrophysics Data System (ADS)

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.

Marzzacco, Charles J.

1999-11-01

25

Dynamic Calorimetry for Students  

ERIC Educational Resources Information Center

A student experiment on dynamic calorimetry is described. Dynamic calorimetry is a powerful technique for calorimetric studies, especially at high temperatures and pressures. A low-power incandescent lamp serves as the sample. The ScienceWorkshop data-acquisition system with DataStudio software from PASCO Scientific displays the results of the…

Kraftmakher, Yaakov

2007-01-01

26

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

Microsoft Academic Search

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.

Ilian Jelesarov; Hans Rudolf Bosshard

1999-01-01

27

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

NASA Technical Reports Server (NTRS)

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.

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

1977-01-01

28

Milk Fat Thermal Properties and Solid Fat Content in Emmental Cheese: A Differential Scanning Calorimetry Study  

Microsoft Academic Search

The experiments reported in this study give deeper insightintothecrystallizationofmilkfatinEmmental cheese,whichisthemostwidelyconsumedhardcheese in France. Differential scanning calorimetry (DSC) was used to monitor the thermal properties of milk fat after the main stages involved during manufacture of Emmental cheese. By heating the samples to 60° Ct o eliminate their thermal history and cooling them at 2°C\\/min, the liquid ? solid phase transition of

C. Lopez; V. Briard-Bion; B. Camier; J.-Y. Gassi

2006-01-01

29

Thermal Characterization and Model Free Kinetics of Aged Epoxies and Foams Using TGA and DSC Methods.  

National Technical Information Service (NTIS)

Two classes of materials, poly(methylene diphenyl diisocyanate) or PMDI foam, and cross-linked epoxy resins, were characterized using thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC), to help understand the effects of aging a...

A. Nissen A. M. Kruizenga J. G. Cordaro

2013-01-01

30

Air Fluorescence Calorimetry with the High Resolution Fly's Eye and Telescope Array Experiments  

SciTech Connect

The air fluorescence technique was first successfully deployed on the Fly's Eye Experiment (1981-1993) by the University of Utah. Its successor, the High Resolution Fly's Eye (HiRes) experiment has further exploited this technique, first in hybrid mode with the MIA muon array (1993-1996), and then in monocular and stereoscopic modes (1997-2006). Results from HiRes will be presented, including evidence for the Greisen-Zatsepin-K'uzmin (GZK) Effect predicted 40 years ago. Most recently, members of the HiRes are collaborating with groups from Japan, led by University of Tokyo, to construct and operate the Telescope Array (TA) experiment, which will deploy a large scintillation-based ground array in combination with fluorescence detectors. Funding for TA in the US has already been approved by NSF. TA will begin operation in 2007.

Jui, Charles C. H. [Department of Physics, University of Utah Salt Lake City, Utah (United States)

2006-10-27

31

DSC and Raman spectroscopy study of glass transition in tektites  

Microsoft Academic Search

Tektite glasses are products of meteor or asteroid impacts on the Earth, during which the solid rock was melted, evaporated and condensed into a glass in the atmosphere. This work aimed to estimate the glass transition temperature Tg and possible cooling rates (q) of tektites by the use of differential scanning calorimetry with compensated heat flux (DSC) and Raman high

N. Bagdassarov; D. Neuville; Y. Linard; O. Lukanin; A. Kadik

2003-01-01

32

FTIR AND DSC STUDIES OF MECHANICALLY DEFORMED ?-PVDF FILMS  

Microsoft Academic Search

Films of semicrystalline poly(vinylidene fluoride) (PVDF) in the ?-phase were studied by Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). The main goal of this study was to improve the understanding of the structural changes that occur in ?-PVDF during a mechanical deformation process. FTIR spectroscopy was used to examine the structural variations as a function of strain.

S. Lanceros-Méndez; J. F. Mano; A. M. Costa; V. H. Schmidt

2001-01-01

33

Quantum Calorimetry  

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

34

Differential scanning calorimetry in the study of lipid phase transitions in model and biological membranes: practical considerations.  

PubMed

Differential scanning calorimetry (DSC) is a relatively rapid, straightforward, and nonperturbing technique for studying the thermotropic phase behavior of hydrated lipid dispersions and of reconstituted lipid model or biological membranes. However, because of the diversity of lipid thermotropic phase behavior, data-acquisition and data-analysis protocols must be modified according to the nature of the phase transition under investigation. In this chapter, the theoretical basis of the DSC experiment is examined and, with the aid of specific examples, also how the information content of DSC thermograms is affected by the nature of the lipid phase transition examined. The overall goal is to provide practical guidelines for the development of data-acquisition and data-analysis protocols, which are compatible with the instrumentation available and the nature of the lipid phase transition under investigation. PMID:17951734

Lewis, Ruthven N A H; Mannock, David A; McElhaney, Ronald N

2007-01-01

35

TMA, DMA, DSC and TGA of lead free solders  

Microsoft Academic Search

Most of the electronics packaging materials, especially solders, are temperature dependent. Their temperature-dependent material properties can be obtained by TMA (thermal mechanical analysis), DMA (dynamic mechanical analysis), DSC (differential scanning calorimetry), and TGA (thermogravimetric analysis). In this study, the thermal coefficient of expansion (TCE), storage modulus, moisture uptake, and melting point of two lead free solders, 96.5wt%Sn-3.5wt%Ag and 42wt%Sn-58wt%Bi provided

John H. Lau; Chris Chang

1999-01-01

36

Glass transition in polymers: Comparison of results from DSC, TMA, and TOA measurements  

SciTech Connect

The determination of the glass transition temperature, T{sub g}, of polymers by differential scanning calorimetry (DSC) and thermomechanical analysis (TMA) is sometimes problematic and rather subjective. This was shown previously in the ICTA certificate (distributed by NBS as GM-754) for the certified reference material polystyrene (PS). The not very good reproducibility of the measured value of the onset is due to a variety of instrumental and experimental parameters. This is true also for the determination of the glass transition by TMA measurements. The main reasons are temperature gradients caused by the relatively high sample mass required for DSC and by the limited heat transfer in TMA, respectively. Their own experiments which were carried out with polystyrene and with [poly(ethyleneterephthalate)] (PET) proved that a combination of DSC with TOA (thermo-optical analysis or hot stage microscopy under polarized light) can solve some of these problems. TOA is a nonsubjective method since the changes in birefringence and light transmittance during the glass transition which are visible under the microscope are measured with a photocell. TOA allows T{sub g} measurements of small samples (fraction of milligrams).

Wiedemann, H.G.; Widmann, G. [Mettler-Toledo AG, Greifensee (Switzerland); Bayer, G. [Swiss Federal Inst. of Technology, Zurich (Switzerland). Inst. of Non-metallic Materials

1994-09-01

37

Characterization of the kinetic behavior of resin modified Glass-ionomer cements by DSC, TMA and ultrasonic wave propagation  

Microsoft Academic Search

In this study the isothermal kinetic behavior of two resin modified glass ionomer cements (RMGIC) and a dental composite have been compared by differential scanning calorimetry (DSC) and thermo-mechanical analysis (TMA). The simultaneous evolution of the multiple reactions occurring in RMGIC has been analyzed not only by DSC and TMA but also by ultrasonic wave propagation using the pulse-echo technique.

F. Micelli; A. Maffezzoli; R. Terzi; V. A. M. Luprano

2001-01-01

38

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, ...

39

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

PubMed

A mathematical equation has been derived to calculate the liquidus for a binary system consisting of an amorphous polymer and a crystalline low molar mass compound. The experimental input to this equation is an interaction enthalpy, which is derived from the variation of the melting enthalpy with composition in differential scanning calorimetry (DSC) experiments. The predictive power of the equation has been tested with mixtures of acetylsalicylic acid, carbamazepine, or intraconazole with poly(ethylene glycol) as well as mixtures of carbamazepine with poly(acrylic acid), poly(hydroxystyrene), or poly(vinylpyrrolidone). It has been confirmed that the evaluation of the melting enthalpy in DSC is a suitable method to identify the preferred solute-polymer combinations for thermodynamically stable molecular dispersions. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci. PMID:24723307

Rager, Timo

2014-06-01

40

Temperature-modulated DSC provides new insight about nickel-titanium wire transformations  

Microsoft Academic Search

Differential scanning calorimetry (DSC) is a well-known method for investigating phase transformations in nickel-titanium orthodontic wires; the microstructural phases and phase transformations in these wires have central importance for their clinical performance. The purpose of this study was to use the more recently developed technique of temperature-modulated DSC (TMDSC) to gain insight into transformations in 3 nickel-titanium orthodontic wires: Neo

William A Brantley; Masahiro Iijima; Thomas H Grentzer

2003-01-01

41

The determination of Curie temperature by differential scanning calorimetry under magnetic field  

Microsoft Academic Search

Differential scanning calorimetry (DSC) has been shown to be a convenient and accurate method for measuring Curie temperature (T c) in terms of the observation that the heat flow has a visible variation at the transition point. An improved method is presented which involves the application of an axial magnetic field on samples during the DSC scanning process. The heat

M. S. Leu; C. S. Tsai; C. S. Lin; S. T. Lin

1991-01-01

42

Quantitative Thermal Analysis of Poly(butylene Terephthalate) by Temperature-Modulated Differential Scanning Calorimetry  

Microsoft Academic Search

Quantitative thermal analysis is performed on poly(butylene terephthalate), PBT, between 5 and 600 K based on the measured heat capacity by adiabatic calorimertry, standard differential scanning calorimetry (DSC) and temperature-modulated differential scanning calorimetry (TMDSC). Based on the new data, the low temperature heat capacity is linked to the vibrational spectrum, using the ATHAS method to calculate the solid heat capacity

M. Pyda; E. Nowak-Pyda; B. Wunderlich

2004-01-01

43

Ice premelting during differential scanning calorimetry  

PubMed Central

Premelting at the surface of ice crystals is caused by factors such as temperature, radius of curvature, and solute composition. When polycrystalline ice samples are warmed from well below the equilibrium melting point, surface melting may begin at temperatures as low as -15 degrees C. However, it has been reported (. Biophys. J. 65:1853-1865) that when polycrystalline ice was warmed in a differential scanning calorimetry (DSC) pan, melting began at about -50 degrees C, this extreme behavior being attributed to short-range forces. We show that there is no driving force for such premelting, and that for pure water samples in DSC pans curvature effects will cause premelting typically at just a few degrees below the equilibrium melting point. We also show that the rate of warming affects the slope of the DSC baseline and that this might be incorrectly interpreted as an endotherm. The work has consequences for DSC operators who use water as a standard in systems where subfreezing runs are important.

Wilson, PW; Arthur, JW; Haymet, AD

1999-01-01

44

Nucleic acid-lipid membrane interactions studied by DSC  

PubMed Central

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

Giatrellis, Sarantis; Nounesis, George

2011-01-01

45

Curing of a thermosetting powder coating by means of DMTA, TMA and DSC  

Microsoft Academic Search

The curing of a thermosetting powder coating made up of carboxyl-terminated polyester and triglycidylisocyanurate (TGIC) was studied by means of dynamic mechanical thermal analysis (DMTA), thermal mechanical analysis (TMA) and differential scanning calorimetry (DSC). On the basis of isothermal curing of the coating on different supports with DMTA and TMA, we determine the degree of mechanical curing. The degree of

X Ramis; A Cadenato; J. M Morancho; J. M Salla

2003-01-01

46

Structural analysis of w \\/ o \\/ w multiple emulsions by means of DSC  

Microsoft Academic Search

The properties of the inner and the external aqueous phases, were studied in w\\/o\\/w multiple emulsions with light microscopic image analysis and differential scanning calorimetry (DSC). The importance of multiple emulsions lies in the presence of these aqueous phases, making them available for sustained, controlled drug delivery systems. Differentiation of these two aqueous phases, studying the effect of manufacturing technology

Anita Kovács; I. Csóka; Magdolna Kónya; E. Csányi; A. Fehér; I. Er?s

2005-01-01

47

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)

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-1HPISEMA 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.

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

2013-03-01

48

Pyrolysis combustion flow calorimetry  

Microsoft Academic Search

A method for evaluating the combustibility of milligram samples is described. Pyrolysis-combustion flow calorimetry (PCFC) separately reproduces the solid state and gas phase processes of flaming combustion in a nonflaming test by controlled pyrolysis of the sample in an inert gas stream followed by high temperature oxidation of the volatile pyrolysis products. Oxygen consumption calorimetry is used to measure the

Richard E Lyon; Richard N Walters

2004-01-01

49

DMSO-induced dehydration of DPPC membranes studied by x-ray diffraction, small angle neutron scattering and calorimetry.  

National Technical Information Service (NTIS)

The properties of dimethyl sulfoxide (DMSO), a cryoprotector well known for its biological and therapeutic applications, were investigated on lipid membranes by x-ray diffraction, differential scanning calorimetry (DSC) and small angle neutron scattering ...

M. A. Kiselev A. M. Kiselev P. Lesieur C. Grabielle-Madelmond M. Ollivon

1998-01-01

50

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

Microsoft Academic Search

Establishing safe handling limits for explosives in elevated temperature environments is a difficult problem that often requires extensive simulation. The largest influence on predicting thermal cookoff safety lies in the chemical kinetic model used in these simulations, and these kinetic model reaction sequences often contain multiple steps. Several small-scale cookoff experiments, notably Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), One-Dimensional

A P Wemhoff; R C Becker; A K Burnham

2008-01-01

51

Glass Transition of Freeze-concentrated Aqueous Solution of Ascorbic Acid as Studied by Alternating Differential Scanning Calorimetry  

Microsoft Academic Search

Aqueous solutions of ascorbic acid have been shown, using differential scanning calorimetry (DSC), to form glassy states during freezing. Alternating DSC, as a new technique, further helped to assign five thermal events observed during heating of frozen ascorbic acid solutions to complete melting from below Tg?, the temperature for maximal freeze concentration of ascorbic acid in water, as: (i) glass

Astrid Bork Andersen; Leif H. Skibsted

1998-01-01

52

Differential scanning calorimetry study of ordinary Portland cement paste containing metakaolin and theoretical approach of metakaolin activity  

Microsoft Academic Search

This paper aims to investigate the hydration and pozzolanic reactions in cement pastes with different levels of metakaolin replacement, using differential scanning calorimetry (DSC) and theoretical analysis based on reaction stoichiometry. It was found that the DSC technique could follow the hydration process quantitatively by measuring the peak temperature and enthalpy corresponding to decomposition of hydration products, as functions of

W Sha; G. B Pereira

2001-01-01

53

X-ray diffraction pattern and DSC curves of the discharge product of the lithium\\/sulfur dioxide battery  

Microsoft Academic Search

The X-ray diffraction pattern for the discharge product of the Li\\/SO2 battery has been determined. The diffraction data for the lithium dithionite (Li2S2O4) is presented in a table. Differential scanning calorimetry (DSC) data have indicated that Li2S2O4 undergoes two endothermic reactions and one exothermic reaction. The DSC data reveal also that Li reacts exothermically with Li2S2O4 at the lower endothermic

D. W. Ernst

1982-01-01

54

Elucidation of the complexation mechanism between (+)-usnic acid and cyclodextrins studied by isothermal titration calorimetry and phase-solubility diagram experiments.  

PubMed

In the present work the complexation mechanism between (+)-usnic acid (UA) and cyclodextrins (CDs) has been investigated by isothermal titration calorimetry (ITC) and phase-solubility diagrams using pH as a tool for modifying the molecule ionization. ITC experiments have been employed to evaluate the stoichiometry of interaction (N), affinity constants (K), and thermodynamic parameter variation associated with complexation between (+)-UA and alpha-, beta-, HP-beta-, SBE-beta-, and gamma-CD. It was shown that (+)-UA did not interact with alpha-CD and tended to interact more favorably with gamma-CD (K = 1030 M(-1), DeltaG = -17.18 kJ x mol(-1)) than beta-CD (K = 153 M(-1), DeltaG = -12.46 kJ x mol(-1)) forming 1:1 complexes. It was also demonstrated using ITC and solubilization experiments that chemical modifications of the parent beta-CD resulted in stronger and more spontaneous interactions (K = 281 M(-1), DeltaG = -13.97 kJ x mol(-1) for SBE-beta-CD and K = 405 M(-1), DeltaG = -14.87 kJ x mol(-1) for HP-beta-CD). Analysis of the thermodynamic data suggested that van der Waals forces and hydrogen bonds were responsible for the formation of complexes with a predominance of van der Waals forces. Finally, pH induced modifications of (+)-UA ionization provided important informations relative to the topology of the interaction between (+)-UA molecule and the gamma-CD cavity, which were confirmed by molecular modeling. PMID:19153981

Segura-Sanchez, Freimar; Bouchemal, Kawthar; Lebas, Geneviève; Vauthier, Christine; Santos-Magalhaes, Néréide S; Ponchel, Gilles

2009-01-01

55

Scintillator plate calorimetry  

SciTech Connect

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

Price, L.E.

1990-01-01

56

Calorimetry for the SSC  

SciTech Connect

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.

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

1984-01-01

57

Differential scanning calorimetry of confectionery fats. Pure triglycerides: Effects of cooling and heating rate variation  

Microsoft Academic Search

Differential scanning calorimetry (DSC) measurements of the crystallization and melting phenomena of pure forms of the three\\u000a principal triglycerides present in cocoa butter and related confectionery fats are presented. The results are used to exhibit\\u000a the usefulness of the DSC technique for potential application in quality control of these types of material, but also as a\\u000a warning of the difficulties

Deryck J. Cebula; Kevin W. Smith

1991-01-01

58

Differential scanning calorimetry measurements of kinetic factors involved in salicide process  

NASA Astrophysics Data System (ADS)

Experimental procedure allowing the measurement of kinetic factors controlling the reaction of a nanometric film with a monocrystalline substrate by differential scanning calorimetry (DSC) is described. This technique is shown to be of great interest for characterization of silicide formation during microelectronic industrial processes. Combining both in situ x-ray diffraction measurements (crystal structure) and DSC measurements (formation enthalpy), the interface reaction coefficient Kr and the effective diffusion coefficient Kd characterizing Pd2Si growth have been measured.

Hoummada, K.; Portavoce, A.; Perrin-Pellegrino, C.; Mangelinck, D.; Bergman, C.

2008-03-01

59

Scintillator materials for calorimetry  

SciTech Connect

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.

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

1994-09-01

60

Differential scanning calorimetry study of glycerinated rabbit psoas muscle fibres in intermediate state of ATP hydrolysis  

PubMed Central

Background Thermal denaturation experiments were extended to study the thermal behaviour of the main motor proteins (actin and myosin) in their native environment in striated muscle fibres. The interaction of actin with myosin in the highly organized muscle structure is affected by internal forces; therefore their altered conformation and interaction may differ from those obtained in solution. The energetics of long functioning intermediate states of ATP hydrolysis cycle was studied in muscle fibres by differential scanning calorimetry (DSC). Results SETARAM Micro DSC-II was used to monitor the thermal denaturation of the fibre system in rigor and in the presence of nucleotide and nucleotide analogues. The AM.ADP.Pi state of the ATP hydrolysis cycle has a very short lifetime therefore, we mimicked the different intermediate states with AMP.PNP and/or inorganic phosphate analogues Vi and AlF4 or BeFx. Studying glycerol-extracted muscle fibres from the rabbit psoas muscle by DSC, three characteristic thermal transitions were detected in rigor. The thermal transitions can be assigned to myosin heads, myosin rods and actin with transition temperatures (Tm) of 52.9 ± 0.7°C, 57.9 ± 0.7°C, 63.7 ± 1.0°C. In different intermediate states of the ATP hydrolysis mimicked by nucleotide analogues a fourth thermal transition was also detected which is very likely connected with nucleotide binding domain of myosin and/or actin filaments. This transition temperature Tm4 depended on the mimicked intermediate states, and varied in the range of 66°C – 77°C. Conclusion According to DSC measurements, strongly and weakly binding states of myosin to actin were significantly different. In the presence of ADP only a moderate change of the DSC pattern was detected in comparison with rigor, whereas in ADP.Pi state trapped by Vi, AlF4 or BeFx a remarkable stabilization was detected on the myosin head and actin filament which is reflected in a 3.0 – 10.0°C shift in Tm to higher temperature. A similar effect was observed in the case of the nonhydrolyzable AMP.PNP analogue. Differential DSC measurements suggest that stabilization actin structure in the intermediate states of ATP hydrolysis may play an additional role in actin-myosin interaction.

Dergez, Timea; Lorinczy, Denes; Konczol, Franciska; Farkas, Nelli; Belagyi, Joseph

2007-01-01

61

Modulated differential scanning calorimetry  

Microsoft Academic Search

Modulated DSCTM (MDSC) is a new, patent-pending extension to conventional DSC which provides information about the reversing and nonreversing\\u000a characteristics of thermal events, as well as the ability to directly measure heat capacity. This additional information aids\\u000a interpretation and allows unique insights into the structure and behaviour of materials., A number of examples of its use\\u000a are described.

P. S. Gill; S. R. Sauerbrunn; M. Reading

1993-01-01

62

A comparison of the DSC measurements of shape memory alloys and the material's thermal characteristics in a large scale actuator  

Microsoft Academic Search

An accurate measure of a Shape Memory Alloy's (SMA) transition temperatures is necessary for the development of successful SMA actuator designs. Differential Scanning Calorimetry (DSC) is used to obtain SMA transition temperatures associated with changes in alloy formulations, fabrication processes, and forming methods, and to predict an SMA's thermal characteristics when designed into an actuator. However there is little data

James H. Mabe; Chin-Jye Yu; Ed Rosenzweig

2006-01-01

63

Electrical conductivity, DSC and NMR studies of PEG and PPG containing lithium salts  

Microsoft Academic Search

Complex impedance, differential scanning calorimetry (DSC) and 7Li nuclear magnetic resonance (NMR) studies have been carried out on poly(propylene glycol) (PPG) with an average molecular weight of 4000 and poly(ethylene glycol) mono-methyl-ether with an average molecular weight of 350 (PEG) containing lithium salts. The impedance studies were made over a range of frequencies, temperatures and pressures and were used to

M. C Wintersgill; J. J Fontanella; P. E Stallworth; S. A Newman; S. H Chung; S. G Greenbaum

2000-01-01

64

A DSC study on the kinetics of disproportionation reaction of (hfac)Cu I(COD)  

Microsoft Academic Search

The kinetics of disproportionation reaction of hexafluoroacetylacetonate-copper(I)-cycloocta-1,5-diene [(hfac)CuI(COD)] was investigated by the use of differential scanning calorimetry (DSC) with different heating rates in dynamic nitrogen atmosphere. First, the activation energies (Eas) of the disproportionation reaction were estimated with model-free isoconversional methods, respectively. The Eas were found to fall within the range between 17.6 and 18.7kJmol?1, with no temperature and heating

Gene Chen; Chiapyng Lee; Yu-Lin Kuo; Yee-Wen Yen

2007-01-01

65

Thermodynamic properties of polymorphic forms of theophylline. Part I: DSC, TG, X-ray study  

Microsoft Academic Search

The physicochemical properties of theophylline hydrate and anhydrous polymorphic forms I and II were evaluated using crystallographic\\u000a and calorimetric method. This study has been carried out with the following techniques: differential scanning calorimetry\\u000a (DSC), thermogravimetric analysis (TG) and X-ray diffractometry. The X-ray patterns on powder for investigated compounds are\\u000a presented.

Piotr Szterner; Bernard Legendre; Mehrez Sghaier

2010-01-01

66

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

Microsoft Academic Search

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.

R. M. Paroli; J. Penn

1994-01-01

67

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

Microsoft Academic Search

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

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

2005-01-01

68

Cold crystallization effects in PET and PEN by TSDC, DSC and X-ray diffraction  

Microsoft Academic Search

A comparative study of the different relaxations present in amorphous and partially crystallized poly(ethylene-2,6-naphthalene dicarboxylate) (PEN) and poly(ethylene terephthalate) (PET) has been carried out by thermally stimulated depolarization currents (TSDC), differential scanning calorimetry (DSC), and X ray diffraction. Amorphous films have been crystallized thermically at temperatures between 170°C and 200°C (PEN); 100°C and 150°C (PET) by the thermal stimulation by

J. C. Canadas; J. A. Diego; J. Sellares; M. Mudarra; J. Belana

1999-01-01

69

Characterization of water state and distribution in textured soybean protein using DSC and NMR  

Microsoft Academic Search

To explore the role of water during extrusion cooking and the scientific basis for demarcating low-intermediate moisture and high-moisture extrusion technique, soybean protein isolate (SPI) was processed using a pilot-scale twin-screw extruder under 28–60% moisture content and 140–160°C cooking temperature. The state of water in textured soybean protein (TSP) with different treatments were analyzed by using differential scanning calorimetry (DSC)

Feng Liang Chen; Yi Min Wei; Bo Zhang

2010-01-01

70

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

PubMed Central

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

Chiu, Michael H.; Prenner, Elmar J.

2011-01-01

71

Isothermal Titration Calorimetry of RNA  

PubMed Central

Isothermal titration calorimetry (ITC) is a fast and robust method to study the physical basis of molecular interactions. A single well-designed experiment can provide complete thermodynamic characterization of a binding reaction, including Ka, ?G, ?H, ?S and reaction stoichiometry (n). Repeating the experiment at different temperatures allows determination of the heat capacity change (?CP) of the interaction. Modern calorimeters are sensitive enough to probe even weak biological interactions making ITC a very popular method among biochemists. Although ITC has been applied to protein studies for many years, it is becoming widely applicable in RNA biochemistry as well, especially in studies which involve RNA folding and RNA-interactions with small molecules, proteins and with other RNAs. This review focuses on best practices for planning, designing, and executing effective ITC experiments when one or more of the reactants is an RNA.

Salim, Nilshad N.; Feig, Andrew L.

2009-01-01

72

In Situ Stability of Substrate-Associated Cellulases Studied by DSC.  

PubMed

This work shows that differential scanning calorimetry (DSC) can be used to monitor the stability of substrate-adsorbed cellulases during long-term hydrolysis of insoluble cellulose. Thermal transitions of adsorbed enzyme were measured regularly in subsets of a progressing hydrolysis, and the size of the transition peak was used as a gauge of the population of native enzyme. Analogous measurements were made for enzymes in pure buffer. Investigations of two cellobiohydrolases, Cel6A and Cel7A, from Trichoderma reesei, which is an anamorph of the fungus Hypocrea jerorina, showed that these enzymes were essentially stable at 25 °C. Thus, over a 53 h experiment, Cel6A lost less than 15% of the native population and Cel7A showed no detectable loss for either the free or substrate-adsorbed state. At higher temperatures we found significant losses in the native populations, and at the highest tested temperature (49 °C) about 80% Cel6A and 35% of Cel7A was lost after 53 h of hydrolysis. The data consistently showed that Cel7A was more long-term stable than Cel6A and that substrate-associated enzyme was less long-term stable than enzyme in pure buffer stored under otherwise equal conditions. There was no correlation between the intrinsic stability, specified by the transition temperature in the DSC, and the long-term stability derived from the peak area. The results are discussed with respect to the role of enzyme denaturation for the ubiquitous slowdown observed in the enzymatic hydrolysis of cellulose. PMID:24856176

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

2014-06-24

73

Extruded scintillator for the Calorimetry applications  

SciTech Connect

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

Dyshkant, A.; Rykalin, V.; Pla-Dalmau, A.; Beznosko, D. [Northern Illinois Center for Accelerator and Detector Development (NICADD), Northern Illinois University, DeKalb, IL 60115 (United States); Fermi Nationa Acceleratorl Laboratory, Batavia, IL 60510 (United States); State University of New York at Stony Brook, Stony Brook, NY 11790 (United States)

2006-10-27

74

Overview on calorimetry  

NASA Astrophysics Data System (ADS)

In this paper I want to review the state of the art of calorimeter developments. I will focus on innovative solutions in calorimetry at the technology frontier and I will favor calorimeters for High Energy Physics detectors. The field in which calorimeters find their application is so broad that this short review does not do justice to all ongoing projects. Instead, this paper shall be considered as a collection of currently hot topics on the subject.

Garutti, Erika

2011-02-01

75

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

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

76

Characterization of petroleum products by DSC analysis  

Microsoft Academic Search

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.

C. Giavarini; F. Pochetti

1973-01-01

77

Characterization of chitin, chitosan and their carboxymethyl derivatives by differential scanning calorimetry  

Microsoft Academic Search

Chitin, chitosan and their O,N-carboxymethyl derivatives were characterized by differential scanning calorimetry (DSC) mainly focusing on changes in physical and chemical structures at different levels of acetyl and carboxymethyl contents. The thermograms were characterized by endo- and exotherms corresponding to water evaporation and decomposition of the polymer, respectively. However, each endo- or exothermic peak temperature and area changed as a

F. S. Kittur; K. V. Harish Prashanth; K. Udaya Sankar; R. N. Tharanathan

2002-01-01

78

Controlled rate thermal analysis and differential scanning calorimetry of sepiolites and palygorskites  

Microsoft Academic Search

A series of sepiolites, palygorskites and “Rocky Mountain Leather” (RML) clay minerals have been analysed by controlled rate thermal analysis and differential scanning calorimetry (DSC). Eight weight loss steps are observed and are structure and composition dependent. Three dehydration steps and five dehydroxylation steps are observed. The mass spectrometric curve mimicked the differential thermogravimetric (DTGA) curve enabling the detailed determination

R. L. Frost; Z. Ding

2003-01-01

79

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

PubMed Central

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

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

2006-01-01

80

Cure kinetics of epoxy matrix resin by differential scanning calorimetry  

NASA Technical Reports Server (NTRS)

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.

Cizmecioglu, M.; Gupta, A.

1982-01-01

81

Effects of xyloglucan on the gelatinization and retrogradation of corn starch as studied by rheology and differential scanning calorimetry  

Microsoft Academic Search

Effects of xyloglucan (XG) on gelatinization and retrogradation of corn starch (CS) were studied as a function of mixing ratio and of storage time and by measuring force-deformation curves, dynamic viscoelasticity, syneresis and differential scanning calorimetry (DSC). Total polysaccharide concentrations were 3.5wt% or 20wt% and CS\\/XG mixing ratios were 10\\/0, 9.5\\/0.5, 9.0\\/1.0 and 8.5\\/1.5. Results of dynamic viscoelasticity and DSC

Miki Yoshimura; Tomohisa Takaya; Katsuyoshi Nishinari

1999-01-01

82

Kinetics of non-isothermal oxidation of anhydrous milk fat rich in conjugated linoleic acid using differential scanning calorimetry  

Microsoft Academic Search

Anhydrous milk fat (AMF) with low, medium, and high content of conjugated linoleic acid (L-, M-, and H-CLA) was oxidized using\\u000a differential scanning calorimetry (DSC) at five different heating rates (3, 6, 9, 12, and 15 °C min?1) in a temperature range of 100–350 °C. For the first time, kinetic oxidation parameters of AMF rich in CLA are reported.\\u000a DSC spectra were analyzed

Sergio I. Martínez-Monteagudo; Marleny D. A. Saldaña; John J. Kennelly

83

Aggregate structure of “single-nano buckydiamond” in gel and dried powder by differential scanning calorimetry and nitrogen adsorption  

Microsoft Academic Search

Gels and dried powders of the single-nano buckydiamond (SNBD) have been studied by means of differential scanning calorimetry (DSC) and gas adsorption methods. Nanophase of water (NPhW) was confirmed in SNBD hydrogel by DSC, wherein the characteristic feature at 265K was observed and attributed to melting of NPhW. No such feature was observed in commercial agglutinate samples of detonation nanodiamond.

Mikhail V. Korobov; Maria M. Batuk; Natalia V. Avramenko; Nina I. Ivanova; Natalia N. Rozhkova; Eiji ?sawa

2010-01-01

84

A study of PBT\\/PC blends by modulated DSC and conventional DSC  

Microsoft Academic Search

Two poly(butylene terephthalate)\\/polycarbonate (PBT\\/PC) blends with different formulations were analyzed by modulated DSC (MDSC) and conventional DSC to determine differences in crystallization behavior. A significant difference (30°C in cold crystallization temperature) between the two samples was detectable by MDSC while no significant difference was seen by conventional DSC. That indicatesthe total heat flow from MDSC is not always equivalent to

Yimin Jin; J. Bonilla; Ye-Gang Lin; J. Morgan; Linda McCracken; J. Carnahan

1996-01-01

85

X-ray diffraction pattern and DSC curves of the discharge product of the lithium/sulfur dioxide battery  

NASA Astrophysics Data System (ADS)

The X-ray diffraction pattern for the discharge product of the Li/SO2 battery has been determined. The diffraction data for the lithium dithionite (Li2S2O4) is presented in a table. Differential scanning calorimetry (DSC) data have indicated that Li2S2O4 undergoes two endothermic reactions and one exothermic reaction. The DSC data reveal also that Li reacts exothermically with Li2S2O4 at the lower endothermic temperatures. These exothermic reactions could initiate thermal runaway and be responsible for the problems which occur when Li/SO2 batteries are subjected to current reversal.

Ernst, D. W.

1982-03-01

86

Surface properties of CuCl 2/AC catalysts with various Cu contents: XRD, SEM, TG/DSC and CO-TPD analyses  

NASA Astrophysics Data System (ADS)

Surface properties of CuCl 2/activated carbon (AC) catalyst for dimethyl carbonate synthesis were studied by CO-TPD, XRD, SEM and thermogravimetry (TG)/differential scanning calorimetry (DSC) with varying Cu contents. CuCl 2/AC catalysts were prepared by impregnating AC with CuCl 2-ethanol solution in the range of Cu content from 2.8 to 18.7 wt.%. CuCl 2·2H 2O crystalline phase as active sites was gradually increased with an increase in Cu content. Appearance of CuCl 2·2H 2O was clearly identified by XRD and SEM. In relatively low Cu contents, 4.6 and 9.9 wt.%, CuCl 2·2H 2O was not detected in XRD. This indicates the formation of good dispersion of CuCl 2 compounds on activated carbon. However, DSC result revealed that CuCl 2·2H 2O was formed in multi-layers for the catalyst with Cu content more than 9.9 wt.%, which limit the catalyst activity. This fact was also strongly supported by CO-TPD experiment. The two CuCl 2/AC catalysts having Cu contents of 4.6 and 9.9 wt.% showed no difference in CO adsorption amount in TPD experiments.

Han, Man Seok; Lee, Byung Gwon; Ahn, Byoung Sung; Moon, Dong Ju; Hong, Suk In

2003-04-01

87

Infrared spectroscopy and differential scanning calorimetry studies of binary combinations of cis-6-octadecenoic acid and octadecanoic acid.  

PubMed

Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC) studies are reported for combinations of cis-6-octadecenoic acid (also termed petroselinic acid, PSA) and octadecanoic acid (also termed stearic acid, SA) across a wide range of binary mole ratio combinations. The data are then used to plot the phase diagram which is found to be montotectic with the PSA reducing the melting temperature of SA at all compositions. The relevance of these experiments to stratum corneum (SC) biophysical behavior, particularly the influence and potential mechanisms of PSA on dermal permeation, is discussed. The potential role of cis-6-octadecenoic acid as a permeation enhancer is discussed in the context of these studies of its interaction with saturated fatty acids. PMID:17697674

Moore, David J; Koelmel, Donald; Laura, Donna; Bedford, Eilidh

2007-11-01

88

Differential scanning calorimetry as a tool to estimate binding parameters in multiligand binding proteins.  

PubMed

The stability of proteins and their interactions with other molecules is a topic of special interest in biochemistry because many cellular processes depend on that. New methods and approaches are constantly developed to elucidate the energetics of biomolecular recognition. In this sense, the application of the theory of macromolecular unfolding linked to ligand binding to differential scanning calorimetry (DSC) has proved to be a useful tool to simultaneously characterize the energetics of unfolding and binding. Although the general theory is well known, the applicability of DSC to study the interaction of biomolecules is not common. In the current work, we estimated the binding parameters of 8-anilinonaphthalene-1-sulfonic acid to human serum albumin using DSC. This model system was chosen due to both the complex stoichiometry and the moderate binding constants. From DSC curves acquired at different ligand concentrations, we obtained the number of bound ligands, the binding constants, and the binding enthalpy for each independent binding site. Compared with those parameters determined by titration calorimetry, the results highlight the potentiality of DSC to estimate binding parameters in multiligand binding proteins. PMID:16434020

Celej, M Soledad; Dassie, Sergio A; González, Martín; Bianconi, M Lucia; Fidelio, Gerardo D

2006-03-15

89

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

PubMed Central

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.

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

2014-01-01

90

Acrylonitrile-sodium methallylsulfonate copolymer. DSC approach to membrane porosity of foam and hollow fibers.  

PubMed

The porosity of membranes formed from acrylonitrile-sodium methallylsulfonate copolymer was characterized from the analysis of the depression of the melting point of absorbed water. Membranes were obtained either as a foam or as a hollow fiber; the foam consisted of interconnected macrocavities (mean diameter about equal to 1 mm) while the hollow fiber was a symmetric membrane used for blood ultrafiltration. Differential scanning calorimetry (DSC) of water revealed both the Gaussian distribution of pore sizes and correspondingly, their mean size: 5.2 nm for the pores through the walls separating macrocavities in the foam and 5.6 and 10.6 nm associated with two distributions representing nearly equal amounts of absorbed water, for the hollow fiber. In addition to DSC, the water magnetic relaxation showed that the isothermal dehydration of the foam was due to the deswelling of macrocavities while the increasing amount of absorbed water in pores reflects its strong interaction with the polymer. PMID:12417191

Cohen-Addad, J P; Prunelet, A; Bazile, J P; Buda, A; Thomas, M

2003-01-01

91

Kinetic analysis of an asymmetrical DSC peak in the curing of an unsaturated polyester resin catalysed with MEKP and cobalt octoate  

Microsoft Academic Search

In this paper, the curing of an unsaturated polyester resin catalysed with methyl ethyl ketone peroxide (MEKP) and cobalt octoate as the promoter, is studied at different heating rates. Given the non-symmetrical shape of differential scanning calorimetry (DSC) curves, it has been assumed that they would represent two independent reactions. The objective of this work has been to obtain a

J. L. Mart??n

1999-01-01

92

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

Microsoft Academic Search

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.

M. Peltzer; A. Jiménez

2009-01-01

93

DSC studies on structural phase transitions and molecular motions in some A2MCl4 compounds  

NASA Astrophysics Data System (ADS)

Structural phase transitions and molecular motions in (CH3NH3)2CoCl4, (C5H5NH)2ZnCl4, and [(CH3)3CNH3]2ZnCl4 were investigated by differential scanning calorimetry (DSC) between about 130 K and the melting points. All of the compounds showed at least one structural phase transition over the temperature region investigated. The values of the transition entropies obtained suggest that most of the transitions are of the order-disorder type. From these entropy values, thermal motions of the molecules in the highest-temperature solid phases were inferred.

Horiuchi, Keizo

2004-03-01

94

DSC study on the thermal stability of solid polymer electrolyte cells  

NASA Astrophysics Data System (ADS)

A novel Li-ion polymer battery (Li-IonPB) based on LiNi 0.8Co 0.2O 2 as a cathode and an alternative composite anode (CA) is proposed for future application in hybrid electric vehicles (HEV). A micro-Li-ion polymer cell is prepared in situ inside the differential scanning calorimetry (DSC) sample pan, and the exothermic heat development is compared with that of the micro-lithium-solid polymer electrolyte cell. The thermal decomposition of both cells is further investigated from a qualitative point of view.

Capiglia, C.; Yang, J.; Imanishi, N.; Hirano, A.; Takeda, Y.; Yamamoto, O.

95

WA80 BGO calorimetry electronics  

SciTech Connect

This paper describes instrumentation designed for BGO scintillator-based calorimetry of particles covering a very wide range of energies (from less than 50 MeV to t0 GeV). The instrumentation was designed to have a measurement accuracy of 0.1% over as much of the energy range as possible so the energy resolution of BGO would be the limiting factor. Two 1.5-cm[sup 2] photodiodes were used per 2.5 cm [times] 2.5 cm [times] 25 cm BGO crystal. Both a charge-sensitive preamplifier and a pulse processor were developed specifically for the needs of the WA80 experiment. The preamplifier was designed for high detector capacitance (100 to 700 pF), low integral and differential non-linearity and low power consumption (200 mW). The pulse processor is a time-invariant shaping amplifier with integral peak-detect-and -hold and automatic gain selection circuits. The amplifier uses quasi-triangular shaping with 4 [mu]s peaking time, and the hold circuit is gated with a fast first level trigger. The preamplifier and pulse processor combination has more than 20 bits of effective resolution when used with an external 12-bit ADC. An array of BGO instrumented with 100 preamplifiers and pulse processors was used in beam tests at CERN. Preliminary results from those tests are presented.

Wintenberg, A.L.; Britton, C.L. Jr.; Ericson, M.N.; Maples, R.A.; Young, G.R.; Awes, T.C. (Oak Ridge National Lab., TN (United States))

1992-10-01

96

WA80 BGO calorimetry electronics  

SciTech Connect

This paper describes instrumentation designed for BGO scintillator-based calorimetry of particles covering a very wide range of energies (from less than 50 MeV to 50 GeV). The instrumentation was designed to have a measurement accuracy of 0.1% over as much of the energy range as possible so the energy resolution of BGO would be the limiting factor. Two 1.5-cm{sup 2} photodiodes were used per 2.5 cm {times} 2.5 cm {times} 25 cm BGO crystal. Both a charge-sensitive preamplifier and a pulse processor were developed specifically for the needs of the WA80 experiment. The preamplifier was designed for high detector capacitance (100 to 700 pF), low integral and differential non-linearity and low power consumption (200 mW). The pulse processor is a time-invariant shaping amplifier with integral peak-detect-and-hold and automatic gain selection circuits. The amplifier use quasi-triangular shaping with 4 {mu}s peaking time, and the hold circuit is gated with a fast first level trigger. The system has more than 20 bits of effective resolution when used with an external 12-bit ADC. Results from beam tests at CERN are presented. 6 refs., 5 figs., 1 tab.

Wintenberg, A.L.; Britton, C.L. Jr.; Ericson, M.N.; Maples, R.A.; Young, G.R.; Awes, T.C.

1991-10-31

97

Missing energy induced by thin hadron calorimetry  

SciTech Connect

It is relatively straightforward to estimate the total, unsegmented, depth required in SSC experiments. Typically depths in the range of 9--11 absorption lengths were specified by the SDC and GEM experiments. With these depths, the induced missing energy signal due to calorimeter leakage was found to be well below the signals caused by light gluinos, and the exterior muon systems were well protected from punch through backgrounds. In certain applications, where calorimetry is inscribed inside the magnetic field producing coils, that depth of calorimetry becomes exceedingly expensive. Examples are the ZEUS barrel and the proposed CMS barrel calorimeters. The problems can be alleviated by placing a ``tailcatcher`` of active elements outside the coil, but the problem of inert material placed within the active volume of the calorimetry remains. This inert material can potentially induce missing transverse energy signals which are large with respect to real physics signatures. The purpose of this note is to explore schemes to minimize the measured leakage energy.

Green, D.

1994-04-01

98

Study of crystallization in the Fe 86Cu 1Zr 7B 6 amorphous alloy using FMR and DSC  

NASA Astrophysics Data System (ADS)

The crystallization kinetics of the amorphous metallic alloy Fe 86Cu 1Zr 7B 6 was studied using ferromagnetic resonance (FMR) measurements on samples annealed at 673, 683 and 693 K for several periods of time and differential scanning calorimetry (DSC) using several heating rates between 2 and 30 K/s. The increase of the FMR linewidth with annealing time is attributed to crystallization. Assuming a linear relation between the linewidth increase and the transformed fraction, a value of 1.00±0.05 was obtained for the Avrami exponent, n. The DSC measurements showed two exothermal peaks, suggesting a crystallization process involving more than one phase. The Avrami exponent calculated from the DSC results for the first peak, n=1.0±0.1, agrees with FMR results within experimental error and is consistent with a diffusion-controlled process with a nucleation rate close to zero.

dos Santos, D. S.; dos Santos, D. R.; de Biasi, R. S.

2002-04-01

99

Changes in myofibrillar proteins during processing of salted cod ( Gadus morhua) as determined by electrophoresis and differential scanning calorimetry  

Microsoft Academic Search

The effects of salt-curing, drying and rehydration on muscle proteins in cod (Gadus morhua) were studied during the processing of heavily salted cod or “bacalhau”. The aim was to observe conformational stability and possible degradation or denaturation, with sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and differential scanning calorimetry (DSC). The salting process significantly decreased the heat stabilities of both

Kristin Anna Thorarinsdottir; Sigurjon Arason; Margret Geirsdottir; Sigurdur G. Bogason; Kristberg Kristbergsson

2002-01-01

100

New aspects of the interaction of cholesterol with dipalmitoylphosphatidylcholine bilayers as revealed by high-sensitivity differential scanning calorimetry  

Microsoft Academic Search

We have investigated the effects of cholesterol on the thermotropic phase behavior of annealed and unannealed aqueous dispersions of dipalmitoylphosphatidylcholine (DPPC) using high-sensitivity differential scanning calorimetry (DSC), concentrating particularly on the cholesterol concentration range from 0 to 20 mol%. We find that the incorporation of cholesterol into low-temperature annealed DPPC bilayers decreases the enthalpy of the subtransition without affecting the

Todd P. W McMullen; Ronald N McElhaney

1995-01-01

101

Physicochemical characterization of base stocks and thermal analysis by differential scanning calorimetry and thermomicroscopy at low temperature  

Microsoft Academic Search

A conventional base stock, solvent refined (SR) and a hydroisomerized base stock (HI) in which differences in behavior of Pour Point Depressant Additive are observed, have been dewaxed and these oils and their fractions have been characterized by analytical methods and thermal analysis.Differential scanning calorimetry (DSC) is a rapid and valuable technique for characterization of the thermal behavior of lubricating

J. C. Hipeaux; M. Born; J. P. Durand; P. Claudy; J. M. Létoffé

2000-01-01

102

Differential scanning calorimetry study and computer modeling of beta ==> alpha phase transformation in a Ti6Al4V alloy  

Microsoft Academic Search

The relationship between heat-treatment parameters and microstructure in titanium alloys has so far been mainly studied empirically, using characterization techniques such as microscopy. Calculation and modeling of the kinetics of phase transformation have not yet been widely used for these alloys. Differential scanning calorimetry (DSC) has been widely used for the study of a variety of phase transformations. There has

S. Malinov; Z. Guo; W. Sha; A. Wilson

2001-01-01

103

Study of Mercuric Iodide Near Melting Using Differential Scanning Calorimetry Raman Spectroscopy, and X-Ray Diffraction.  

National Technical Information Service (NTIS)

High-temperature studies of mercuric iodide (HgI sub 2 ) involving differential scanning calorimetry (DSC), Raman spectroscopy, and x- ray powder diffraction have failed to confirm the existence of a red-colored tetragonal high-temperature phase called al...

A. Burger S. Morgan H. Jiang E. Silberman M. Schnieber

1987-01-01

104

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

PubMed

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 degrees C, the modeling predicts that IIF should not occur in yeast cooled at <20 degrees C/min and it should occur with near certainty in cells cooled at >or=30 degrees 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 degrees C/min. PMID:19118541

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

2009-04-01

105

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

PubMed Central

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.

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

2013-01-01

106

Rapid Communication: Simultaneous Dsc/ftirs/tma  

NASA Astrophysics Data System (ADS)

This paper reports, for the first time, on a novel technique which combines differential scanning calorimetry and Fourier transform near-infrared spectroscopy with a non-contact fibre optic thermal expansion probe to give simultaneous thermal, spectral and dilatometric information on a polymer sample. The experimental set-up is described in detail and the technique is demonstrated using a polypropylene film sample.

Degamber, B.; Winter, D.; Tetlow, J.; Teagle, M.; Fernando, G. F.

2004-09-01

107

Scan-rate dependence in protein calorimetry: the reversible transitions of Bacillus circulans xylanase and a disulfide-bridge mutant.  

PubMed Central

The stabilities of Bacillus circulans xylanase and a disulfide-bridge-containing mutant (S100C/N148C) were investigated by differential scanning calorimetry (DSC) and thermal inactivation kinetics. The thermal denaturation of both proteins was found to be irreversible, and the apparent transition temperatures showed a considerable dependence upon scanning rate. In the presence of low (nondenaturing) concentrations of urea, calorimetric transitions were observed for both proteins in the second heating cycle, indicating reversible denaturation occurs under those conditions. However, even for these reversible processes, the DSC curves for the wild-type protein showed a scan-rate dependence that was similar to that in the absence of urea. Calorimetric thermograms for the disulfide mutant were significantly less scan-rate dependent in the presence of urea than in the urea-free buffer. The present data show that, just as for irreversible transitions, the apparent transition temperature for the reversible denaturation of proteins can be scan-rate dependent, confirming the prediction of Lepock et al. (Lepock JR, Rithcie KP, Kolios MC, Rodahl AM, Heinz KA, Kruuf J, 1992, Biochemistry 31:12706-12712). The kinetic factors responsible for scan-rate dependence may lead to significant distortions and asymmetry of endotherms, especially at higher scanning rates. This points to the need to check for scan-rate dependence, even in the case of reversible denaturation, before any attempt is made to analyze asymmetric DSC curves by standard thermodynamic procedures. Experiments with the disulfide-bridge-containing mutant indicate that the introduction of the disulfide bond provides additional stabilization of xylanase by changing the rate-limiting step on the thermal denaturation pathway.

Davoodi, J.; Wakarchuk, W. W.; Surewicz, W. K.; Carey, P. R.

1998-01-01

108

Structural studies of agar-gelatin complex coacervates by small angle neutron scattering, rheology and differential scanning calorimetry.  

PubMed

Agar-gelatin complex coacervates are studied by small angle neutron scattering (SANS), rheology (in both flow and temperature scan modes) and differential scanning calorimetry (DSC) in order to probe the microscopic structure of this dense protein-polysaccharide-rich phase. DSC and isochronal temperature sweep (rheology) experiments yielded a characteristic temperature at approximately 35+/-2 degrees C. Rheology data revealed a second characteristic temperature at approximately 75+/-5 degrees C which was absent in DSC thermograms. In the flow mode, shear viscosity (eta) was found to scale with (Carreau model) applied shear rate (gamma ) as: eta(gamma ) approximately (gamma )(-k) with k=1.2+/-0.2 indicating non-Newtonian and shear-thinning features independent of ionic strength. The static structure factor S(q) deduced from SANS data in the low wave vector (0.018 A(-1)

Singh, S Santinath; Aswal, V K; Bohidar, H B

2007-08-01

109

Quantifying metallurgical interactions in solid\\/liquid diffusion couples using differential scanning calorimetry  

Microsoft Academic Search

A novel method using differential scanning calorimetry (DSC) has been developed to quantify the interface kinetics in a solid\\/liquid diffusion couple. The Ag–Cu binary eutectic system is investigated by heating an assembly of Ag base metal and Ag–Cu eutectic foil to 800 °C and holding. The fraction of liquid remaining after various isothermal hold periods is measured by comparing the

M. L. Kuntz; S. F. Corbin; Y. Zhou

2005-01-01

110

Differential scanning calorimetry study of the solidification sequence of austenitic stainless steel  

Microsoft Academic Search

The solidification sequence of austenitic stainless steels can be predicted with thermodynamic calculations. Another way is\\u000a to use models where the value of the Creq.\\/Nieq. ratio determines the relationship between the solidification mode and the composition factor. In this study the solidification\\u000a of AISI 304LN stainless steel at different cooling rates was studied using differential scanning calorimetry (DSC). The samples

Darja Steiner Petrovi?; Grega Klan?nik; Miran Pirnat; Jožef Medved

2011-01-01

111

Modulated differential scanning calorimetry study of blends of poly(butylene terephthalate) with polycarbonate  

Microsoft Academic Search

Modulated differential scanning calorimetry (MDSC) was used to study the glass-transition relaxation behavior in blends of poly(butylene terephthalate) (PBT), a semicrystalline polymer, with polycarbonate (PC), an amorphous polymer. Using a temperature-modulated differential scanning calorimeter (TM-DSC), a sinusoidal temperature oscillation was superimposed upon the underlying linear temperature ramp. The reversing, total, and non-reversing heat flow curves were then analyzed. We examined

Y. Y. Cheng; M. V. Brillhart; Peggy Cebe

1997-01-01

112

Micromegas for imaging calorimetry  

NASA Astrophysics Data System (ADS)

Gaseous detectors have been used in sampling calorimeters for several years and still remain an attractive option for future collider experiments. The use of Micromegas chambers as active elements of a hadronic calorimeter was proposed a few years ago and stirred up exciting developments of this technology. Basic building blocks of large size chambers acting as signal generating and processing units have been designed and fabricated. They were used to construct two chambers of 1 m2 size which after test in muon and pion beams, showed excellent performance. The most important results are presented followed by a discussion of the prospects towards realistic calorimeter modules at a future collider experiment.

Chefdeville, Maximilien; LAPP/LC Group

2012-12-01

113

CALORIMETRY OF TRU WASTE MATERIALS  

SciTech Connect

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

C. RUDY; ET AL

2000-08-01

114

Contactless Calorimetry for Levitated Samples  

NASA Technical Reports Server (NTRS)

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

Lee, M. C.; Dokko, W.

1986-01-01

115

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

PubMed

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

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

2013-10-01

116

A comparison of the DSC measurements of shape memory alloys and the material's thermal characteristics in a large scale actuator  

NASA Astrophysics Data System (ADS)

An accurate measure of a Shape Memory Alloy's (SMA) transition temperatures is necessary for the development of successful SMA actuator designs. Differential Scanning Calorimetry (DSC) is used to obtain SMA transition temperatures associated with changes in alloy formulations, fabrication processes, and forming methods, and to predict an SMA's thermal characteristics when designed into an actuator. However there is little data directly correlating a material's DSC results with its performance in an actuator configuration, particularly for large-scale actuators producing high force and large displacements. In this paper the authors compare the DSC results of several NiTinol samples with the thermal performance of the same material in a rotary actuator. Data are presented for NiTinol torque tubes 14cm (5.5 in) long by 1 cm (0.4 in) in diameter. The tubes were tested over a range of loads exceeding 17 N*m (150 in-lbs) of torque, with angular displacements of more than 60 degrees, and for durations exceeding 3,500 thermal cycles. Data from various NiTinol suppliers, levels of cold work, and a range of aging temperatures is presented. The DSC data is directly compared to the strain vs. temperature hysteresis curves of the same material under various loads; both before and after extended cycling. The value of the DSC measurements as a predictor of a material's thermal characteristics in an actuator configuration is assessed.

Mabe, James H.; Yu, Chin-Jye; Rosenzweig, Ed

2006-04-01

117

LC-circuit calorimetry  

SciTech Connect

We present a new type of calorimeter in which we couple an unknown heat capacity with the aid of Peltier elements to an electrical circuit. The use of an electrical inductance and an amplifier in the circuit allows us to achieve autonomous oscillations, and the measurement of the corresponding resonance frequency makes it possible to accurately measure the heat capacity with an intrinsic statistical uncertainty that decreases as {approx}t{sub m}{sup -3/2} with measuring time t{sub m}, as opposed to a corresponding uncertainty {approx}t{sub m}{sup -1/2} in the conventional alternating current method to measure heat capacities. We have built a demonstration experiment to show the feasibility of the new technique, and we have tested it on a gadolinium sample at its transition to the ferromagnetic state.

Bossen, O.; Schilling, A. [Physik-Institut der Universitaet Zuerich, Winterthurerstrasse 190, 8057 Zuerich (Switzerland)

2011-09-15

118

Calorimetry Triggering in ATLAS  

SciTech Connect

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.

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

119

Linking up of HT-LSCM and DSC measurements to characterize phase diagrams of steels  

NASA Astrophysics Data System (ADS)

The phase transformation sequence during the solidification of carbon steels strongly influences their behavior in the casting process. Therefore, most exact knowledge of the dependence of the transformation characteristics on the steel composition is of highest relevance for process and quality optimization. The influence of alloying elements like C, Mn or Si on phase transformation is well understood as far as their content is rather low. New steel grades, like high-alloyed TRIP- or TWIP-steels contain almost up to 10 wt.-% of Si and Al and 30 wt.-%Mn. The present work focuses on first results of the parallel investigation into phase transformation of Fe-Al-C alloys by means of Differential Scanning Calorimetry (DSC) and Thermo-Optical Analysis (TOA) with a High-Temperature Laser-Scanning-Confocal-Microscope (HT-LSCM). DSC is a well established method for the accurate measurement of all phase transformation temperatures accompanied by significant enthalpy changes. Due to small enthalpy changes, DSC results are limited with respect to the ?/?-transformation. Besides dilatometry and X-ray diffraction, the optical in-situ observation of phase transformation by HT-LSCM proved to be a comprehensive method. After a short description of the methods, results for the Fe-0.4%Al-0.22%C and Fe-1.5%Al-0.22%C systems will be discussed in detail and finally compared with results from computational thermodynamics.

Presoly, P.; Pierer, R.; Bernhard, C.

2012-07-01

120

CASIS1.0: A prototype VLSI front-end ASIC with ultra-large dynamic range and integrated ADC for silicon calorimetry in space experiments  

NASA Astrophysics Data System (ADS)

In the framework of the INFN R&D project CASIS, a 6-channel prototype of an integrated front-end circuit optimized for silicon calorimeters to be used in future astroparticle physics experiments was designed and realized in a CMOS 0.35 ?m technology. Five channels feature a double-gain charge sensitive preamplifier with real-time automatic gain selection, a correlated double sampling filter and, for test purposes, a fully differential, 12-bit cyclic ADC. A sixth channel, featuring only the ADC, is also implemented. The circuit design and test results are presented in this paper. The design goals of a linear dynamic range of 10 4 MIP (50 pC) in "low-gain" mode and a signal-to-noise ratio of 5:1 for single-MIP signals (with an input capacitive load of 300 pF) in "high-gain" mode were achieved.

Bonvicini, Valter; Orzan, Giulio; Zampa, Gianluigi; Zampa, Nicola

2007-03-01

121

Differential scanning calorimetry of coal  

NASA Technical Reports Server (NTRS)

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.

Gold, P. I.

1978-01-01

122

Analysis of polymerization behavior of dental dimethacrylate monomers by differential scanning calorimetry.  

PubMed

The polymerization and copolymerization activity of dental monomers was investigated using the dynamic differential scanning calorimetry (DSC) method. As aliphatic dimethacrylate monomers, ethyleneglycol dimethacrylates with different lengths of ethyleneglycol and urethane dimethacrylates were used. As aromatic dimethacrylates, Bis-GMA (2,2-bis[4-(3-methacryloxy-2-hydroxypropoxy)phenyl]propane), BMPEPP (2,2-bis(4-methacryloxy poly-ethoxyphenyl)propane), and DMB (1,2-dimethacryloyloxy benzene) were used. Ethyleneglycol dimethacrylates showed sharp exothermic peaks, and the maximum temperatures (Tp) at the exothermic peaks of the DSC curves decreased according to the lengths of ethyleneglycols. Among urethane dimethacrylates, UDMA (dimethacryloxyethyl 2,2,4-trimethylhexamethylene diurethane) and DMPHU (di-(2-methacryloxypropyl) hexamethylene diurethane) showed sharp exothermic peaks, but DMEHU (di-(2-methacryloxyethyl) hexamethylene diurethane) showed an endothermic peak as well as exothermic peaks. This suggests that reactions other than polymerization occurred in the case of DMEHU. The polymerization activity of aromatic dimethacrylates was lower than that of ethyleneglycol dimethacrylates and urethane dimethacrylates. The copolymerization activity of TEGDMA (triethyleneglycol dimethacrylate) and DMB was also investigated using the dynamic DSC method. The DSC curves of the copolymerization between DMB and UDMA or BMPEPP showed broad peaks, but the DSC curves of the copolymerization between TEGDMA and UDMA or BMPEPP showed sharp peaks. The copolymerization activity of TEGDMA was better than that of DMB. PMID:10230155

Hayakawa, T; Takahashi, K; Kikutake, K; Yokota, I; Nemoto, K

1999-03-01

123

Oleic and Docosahexaenoic Acid Differentially Phase Separate from Lipid Raft Molecules: A Comparative NMR, DSC, AFM, and Detergent Extraction Study  

PubMed Central

We have previously suggested that the ?-3 polyunsaturated fatty acid, docosahexaenoic acid (DHA) may in part function by enhancing membrane lipid phase separation into lipid rafts. Here we further tested for differences in the molecular interactions of an oleic (OA) versus DHA-containing phospholipid with sphingomyelin (SM) and cholesterol (CHOL) utilizing 2H NMR spectroscopy, differential scanning calorimetry, atomic force microscopy, and detergent extractions in model bilayer membranes. 2H NMR and DSC (differential scanning calorimetry) established the phase behavior of the OA-containing 1-[2H31]palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (16:0-18:1PE-d31)/SM (1:1) and the DHA-containing 1-[2H31]palmitoyl-2-docosahexaenoyl-sn-glycero-3-phosphoethanolamine (16:0-22:6PE-d31)/SM (1:1) in the absence and presence of equimolar CHOL. CHOL was observed to affect the OA-containing phosphatidylethanolamine (PE) more than the DHA-containing PE, as exemplified by >2× greater increase in order measured for the perdeuterated palmitic chain in 16:0-18:1PE-d31/SM (1:1) compared to 16:0-22:6PE-d31/SM (1:1) bilayers in the liquid crystalline phase. Atomic force microscopy (AFM) experiments showed less lateral phase separation between 16:0-18:1PE-rich and SM/CHOL-rich raft domains in 16:0-18:1PE/SM/CHOL (1:1:1) bilayers than was observed when 16:0-22:6PE replaced 16:0-18:1PE. Differences in the molecular interaction of 16:0-18:1PE and 16:0-22:6PE with SM/CHOL were also found using biochemical detergent extractions. In the presence of equimolar SM/CHOL, 16:0-18:1PE showed decreased solubilization in comparison to 16:0-22:6PE, indicating greater phase separation with the DHA-PE. Detergent experiments were also conducted with cardiomyocytes fed radiolabeled OA or DHA. Although both OA and DHA were found to be largely detergent solubilized, the amount of OA that was found to be associated with raft-rich detergent-resistant membranes exceeded DHA by almost a factor of 2. We conclude that the OA-PE phase separates from rafts far less than DHA-PE, which may have implications for cellular signaling.

Shaikh, Saame Raza; Dumaual, Alfred C.; Castillo, Alicia; LoCascio, Daniel; Siddiqui, Rafat A.; Stillwell, William; Wassall, Stephen R.

2004-01-01

124

Calorimetry applied to nucleus-nucleus collisions at ultrarelativistic energies  

SciTech Connect

A general introduction to high-energy calorimetry is presented, together with brief descriptions of the two types of cascades relevant to calorimetric measurements. This is followed by a discussion of ''compensation'' and of the ''e/h'' ratio. A detailed description of two calorimeters designed and constructed for the CERN WA80 experiment are also given. 16 refs., 17 figs., 5 tabs.

Plasil, F.

1988-01-01

125

Enthalpy of formation of the benzoyl radical by photoacoustic calorimetry  

NASA Astrophysics Data System (ADS)

The energetics of the benzoyl radical have been studied by photoacoustic calorimetry. The value obtained for D[PhC(O)-H], 371 ± 11 kJ mol -1 (89 ± 3 kcal mol -1), agrees with an early result derived from iodination kinetic experiments and does not support a recent suggestion that the radical is resonance stabilized.

Simões, J. A. Martinho; Griller, D.

1989-06-01

126

Use of DSC to detect the heterogeneity of hydrothermal stability in the polyphenol-treated collagen matrix.  

PubMed

The hydrothermal stability of the collagen matrixes treated with plant polyphenols (tannins) depends on not only the strength of the polyphenol-collagen interactions but also the distribution uniformity of polyphenolic molecules within the collagen fibrils. Traditional methods of uniformity tests rely heavily on the expertise of workers and are thus subjective. This paper describes a differential scanning calorimetry (DSC) study of the sheepskin collagen samples treated with hydrolyzable tannins, including two commercial tannins' extracts (chestnut and valonea), two pure ellagitannins (vescalagin and castalagin), and six synthetic gallotannins (di-galloyl-ethylene glycol (DGE), tri-galloyl-glycerol, tetra-galloyl-meso-erythritol, penta-galloyl-adonitol, penta-galloyl-glucose, and hexa-galloyl-ducitol). The collagen sample without polyphenol treatment and the sample treated with DGE showed a single sharp peak in their DSC thermogram with a full peak width at half height (fwhh) of 3-4 degrees C. The samples treated with other tannins all showed multiple peak DSC profiles with the fwhh of each peak at about 3-4 degrees C. These multiple peak profiles imply that in these polyphenol-treated samples, there is a distribution of collagen molecules having different hydrothermal stability. The results have demonstrated that DSC offers an objective method to detect the stability heterogeneity of collagen matrixes in the solid state, providing a useful tool for the leather industry to evaluate the uniformity of leather tanning. PMID:14582955

Tang, H R; Covington, A D; Hancock, R A

2003-11-01

127

Hyperspectral image lossless compression using DSC and 2-D CALIC  

Microsoft Academic Search

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

Xueping Yan; Jiaji Wu

2010-01-01

128

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

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

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

2001-01-01

129

Calorimetry at the Linear Collider  

ScienceCinema

The potential to extract physics at the International Linear Collider depends critically on the jet energy resolution of the detector. The design goal is 30%/sqrt(E), which is roughly a factor two better than what has been achieved previously. After a short review of the Linear Collider project, I will discuss a novel approach to the measurement of jets and the resulting requirements on calorimetry. I will present the ongoing vigorous R&D program geared at designing and testing the technical implementation of these new ideas.

130

MOLECULAR CHARACTERIZATION AND FUNCTIONAL EXPRESSION OF THE DSC1 CHANNEL  

PubMed Central

Drosophila Sodium Channel 1 (DSC1) was predicted to encode a sodium channel based on a high sequence similarity with vertebrate and invertebrate sodium channel genes. However, BSC1, a DSC1 ortholog in Blattella germanica, was recently shown to encode a cation channel with ion selectivity towards Ca2+. In this study, we isolated a total of 20 full-length cDNA clones that cover the entire coding region of the DSC1 gene from adults of D. melanogaster by reverse transcription-polymerase chain reaction. Sequence analysis of the 20 clones revealed nine optional exons, four of which contain in-frame stop codons; and 13 potential A-to-I RNA editing sites. The 20 clones can be grouped into eight splice types and represent 20 different transcripts because of unique RNA editing. Three variants generated DSC1 currents when expressed in Xenopus oocytes. Like the BSC1 channel, all three functional DSC1 channels are permeable to Ca2+ and Ba2+, and also to Na+ in the absence of external Ca2+. Furthermore, the DSC1 channel is insensitive to tetrodotoxin, a potent and specific sodium channel blocker. Our study shows that DSC1 encodes a voltage-gated cation channel similar to the BSC1 channel in B. germanica. Extensive alternative splicing and RNA editing of the DSC1 transcripts suggest the molecular and functional diversity of the DSC1 channel.

Zhang, Tianxiang; Liu, Zhiqi; Song, Weizhong; Du, Yuzhe; Dong, Ke

2011-01-01

131

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

Microsoft Academic Search

A newly developed microscopic Fourier transform infrared (FT-IR) spectrometry combined with differential scanning calorimetry (DSC) has been used to investigate simultaneously the thermal response and IR spectral changes in protein structure in porcine stratum corneum (SC) after pretreatment with skin penetration enhancers (propylene glycol (PG), azone\\/PG, oleic acid (OA)\\/PG, vitamin C, and vitamin C+ OA\\/PG). The amide I and II

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

1996-01-01

132

Determination of kinetics parameters of glass transition in glassy Se and glassy Se98M2 alloys using DSC technique  

NASA Astrophysics Data System (ADS)

Glassy Se and Se98M2 (M = Ag, Cd, Zn) alloys are obtained by the melt quenching technique. Differential Scanning Calorimetry (DSC) technique (under non-isothermal conditions) has been applied to see the effects of Ag, Cd, and Zn additives on the glass transition kinetics of Se-rich glassy alloys at different heating rates. The variation of glass transition temperature, T g with the heating rate, ? has been used to investigate the glass transition kinetics. The values of various kinetic parameters such as glass transition temperature, activation energy of glass transition, overall mean bond energy < E>, heat of atomization H S , bond strength (Se-M) have also been calculated.

Dohare, C.; Mehta, N.

2014-02-01

133

A DSC study of water behavior in water-in-oil microemulsions stabilized by sucrose esters and butanol  

Microsoft Academic Search

Sub-zero temperature differential scanning calorimetry (SZT-DSC) has been applied to a model nonionic water-in-oil microemulsion system based on: sucrose esters\\/water\\/1-butanol\\/n-alkanes (C12–C16). The maximum water solubilization was 40, 56 and 80 wt.% for the systems containing n-dodecane, n-tetradecane and n-hexadecane as the oil phase, respectively. Two types of solubilized water have been detected. The so-called ‘bulk’ (free) water present in the

N. Garti; A. Aserin; I. Tiunova; M. Fanun

2000-01-01

134

FTIR and DSC studies of the thermal and photochemical stability of Balanites aegyptiaca oil (Toogga oil).  

PubMed

The oil extracted from the bean of Balanites aegyptiaca was characterized, and its photochemical and thermal stabilization were evaluated. The chemical composition was determined using gas chromatography (GC), revealing that the oil is very rich in unsaturated fatty acids (72% omega-6 and omega-9). The photochemical stability was assessed by subjecting it to artificially accelerated photo-aging and then examining the changes using infrared spectroscopy. The thermal stability was studied at six different temperatures ranging from 130 to 200°C and monitored in situ by differential scanning calorimetry (DSC). The kinetic parameters (EA and k) describing the thermal degradation of this oil were calculated. It has been shown that the antioxidants present in the oil delay the oxidation process (induction period). The degradation of the Toogga oil was compared with that of oleic and linoleic fatty acids. In addition, the degradation of the Toogga oil extracted with hexane was compared to that of the neat oil. PMID:23470324

Gardette, Jean-Luc; Baba, Mohamed

2013-01-01

135

Smectic ordering in polymer liquid crystal-silica aerogel nanocomposites. Studies of DSC and SAXS.  

NASA Astrophysics Data System (ADS)

Two series of side chain liquid crystal (SCLC) polyacrylate-silica aerogel nanocomposites have been investigated by small-angle x-ray scattering (SAXS) and differential scanning calorimetry (DSC). The first series (ex-situ nanocomposite) was obtained by infiltration of a smectic SCLC polyacrylate prepared by polymerisation in solution into monolithic aerogel slabs. The second one (in-situ nanocomposite) was prepared by photopolymerisation of the monomer infiltrated in the aerogel. The results are compared with those obtained for bulk polyacrylates. It is shown that the smectic ordering is not destroyed by confinement in the aerogel. Spacing of the smectic layers and smectic correlation lengths were deduced from the fit of the SAXS profiles to a Lorentzian function with a quadratic correction. The principal results suggest that in-situ polymerisation enhances the degree of order and the stability of the smectic phase in the nanocomposite.

da Silveira, Nádya Pesce; Ehrburger-Dolle, Françoise; Rochas, Cyrille; Rigacci, Arnaud; Pereira, Fabiano Vargas; Merlo, Aloir Antonio; Westfahl, Harry

2009-01-01

136

DNA melting investigated by differential scanning calorimetry and Raman spectroscopy.  

PubMed Central

Thermal denaturation of the B form of double-stranded DNA has been probed by differential scanning calorimetry (DSC) and Raman spectroscopy of 160 base pair (bp) fragments of calf thymus DNA. The DSC results indicate a median melting temperature Tm = 75.5 degrees C with calorimetric enthalpy change delta Hcal = 6.7 kcal/mol (bp), van't Hoff enthalpy change delta HVH = 50.4 kcal/mol (cooperative unit), and calorimetric entropy change delta Scal = 19.3 cal/deg.mol (bp), at the experimental conditions of 55 mg DNA/ml in 5 mM sodium cacodylate at pH 6.4. The average cooperative melting unit (nmelt) comprises 7.5 bp. The Raman signature of 160 bp DNA is highly sensitive to temperature. Analyses of several conformation-sensitive Raman bands indicate the following ranges for thermodynamic parameters of melting: 43 < delta HVH < 61 kcal/mol (cooperative unit), 75 < Tm < 80 degrees C and 6 < (nmelt) < 9 bp, consistent with the DSC results. The changes observed in specific Raman band frequencies and intensities as a function of temperature reveal that thermal denaturation is accompanied by disruption of Watson-Crick base pairs, unstacking of the bases and disordering of the B form backbone. These three types of structural change are highly correlated throughout the investigated temperature range of 20 to 93 degrees C. Raman bands diagnostic of purine and pyrimidine unstacking, conformational rearrangements in the deoxyribose-phosphate moieties, and changes in environment of phosphate groups have been identified. Among these, bands at 834 cm-1 (due to a localized vibration of the phosphodiester group), 1240 cm-1 (thymine ring) and 1668 cm-1 (carbonyl groups of dT, dG and dC), are shown by comparison with DSC results to be the most reliable quantitative indicators of DNA melting. Conversely, the intensities of Raman marker bands at 786 cm-1 (cytosine ring), 1014 cm-1 (deoxyribose ring) and 1092 cm-1 (phosphate group) are largely invariant to melting and are proposed as appropriate standards for intensity normalizations.

Duguid, J G; Bloomfield, V A; Benevides, J M; Thomas, G J

1996-01-01

137

Thermal analysis of palm mid-fraction, cocoa butter and milk fat blends by differential scanning calorimetry  

Microsoft Academic Search

Commercial samples of anhydrous milk fat (AMF), Ivory Coast cocoa butter (CB) and palm mid-fraction (PMF) were blended in\\u000a a ternary system. The melting characteristics of the blends were studied by differential scanning calorimetry (DSC). Results\\u000a suggest that in the studies of interaction involving more than two fats, partial area (Ai) under the melting peak should be converted to partial

P. S. Dimick

1994-01-01

138

Evaluation on gelatinization of buckwheat starch: a comparative study of Brabender viscoamylography, rapid visco-analysis, and differential scanning calorimetry  

Microsoft Academic Search

An investigation was conducted on the pasting behavior of starch from some of the buckwheat (Fagopyrum esculentum Mönch) cultivars introduced from Poland, France and the former Soviet Union and cultivated at the University of Hohenheim.\\u000a A comparative method study was made among Brabender viscoamylography (BV), rapid visco-analysis (RVA) and differential scanning\\u000a calorimetry (DSC). The results showed that most of the

J. Y. Qian; Manfred Kuhn

1999-01-01

139

Differential scanning calorimetry study and computer modeling of ? ? ? phase transformation in a Ti6Al4V alloy  

Microsoft Academic Search

The relationship between heat-treatment parameters and microstructure in titanium alloys has so far been mainly studied empirically,\\u000a using characterization techniques such as microscopy. Calculation and modeling of the kinetics of phase transformation have\\u000a not yet been widely used for these alloys. Differential scanning calorimetry (DSC) has been widely used for the study of a\\u000a variety of phase transformations. There has

S. Malinov; Z. Guo; W. Sha; A. Wilson

2001-01-01

140

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

PubMed

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 (1-15mol%) 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 1mol%) 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 1mol% increased when TAM concentrations increased for DSPC liposomes, indicating an increase in the dynamics of liposomes. The CO stretching and PO2(-) antisymmetric double bond stretching bands were analyzed to study interactions of TAM with head groups of lipids. As the concentrations of TAM increased, dehydration occurred around these functional groups in the polar part of the lipids. The DSC studies on thermal properties of DSPC lipids indicate that TAM eliminated the pre transition, shifted the main phase transition to lower temperatures and broadened the phase transition curve of the liposomes. PMID:24792199

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

2014-09-15

141

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

PubMed

The adulteration of edible fats is a kind of fraud that impairs the physical and chemical features of the original lipid materials. It has been detected in various food, pharmaceutical and cosmeceutical products. Differential scanning calorimetry (DSC) is the robust thermo-analytical machine that permits to fingerprint the primary crystallisation of triacylglycerols (TAGs) molecules and their transition behaviours. The aims of this study was to assess the cross-contamination caused by lard concentration of 0.5-5% in the mixture systems containing beef tallow (BT) and chicken fat (CF) separately. TAGs species of pure and adulterated lipids in relation to their crystallisation and melting parameters were studied using principal components analysis (PCA). The results showed that by using the heating profiles the discrimination of LD from BT and CF was very clear even at low dose of less than 1%. Same observation was depicted from the crystallisation profiles of BT adulterated by LD doses ranging from 0.1% to 1% and from 2% to 5%, respectively. Furthermore, CF adulterated with LD did not exhibit clear changes on its crystallisation profiles. Consequently, DSC coupled with PCA is one of the techniques that might use to monitor and differentiate the minimum adulteration levels caused by LD in different animal fats. PMID:24731324

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

2014-09-01

142

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

NASA Astrophysics Data System (ADS)

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

Pavelki?, V. M.; Beljanski, M. V.; Anti?, K. M.; Babi?, M. M.; Brdari?, T. P.; Gop?evi?, K. R.

2011-12-01

143

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

PubMed

The gelation behavior of mixtures of tamarind seed xyloglucan (TSX) and sodium form gellan (Na-G) was investigated. The storage and loss shear moduli, G' and G'', of the mixtures showed that a thermoreversible gel was obtained although each polysaccharide alone did not form a gel at experimental conditions. The viscoelastic behavior of the mixtures showed a gel formation of TSX and Na-G induced by synergistic interaction. This synergistic interaction was also revealed by differential scanning calorimetry (DSC) and circular dichroism. Although TSX alone did not show any peak in DSC curves, mixtures with only a small amount of Na-G, which by itself did not show any peak, showed a single peak. With increasing Na-G content, another peak began to appear at the same temperature at which a peak of Na-G alone appeared. Thermally induced changes in circular dichroism of the mixtures were different from those expected from the individual behavior of TSX and Na-G. PMID:14606892

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

2003-01-01

144

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

NASA Technical Reports Server (NTRS)

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.

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

145

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

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

146

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

147

Development of state diagram of bovine gelatin by measuring thermal characteristics using differential scanning calorimetry (DSC) and cooling curve method  

Microsoft Academic Search

A state diagram of bovine gelatin was developed by measuring the freezing curve, glass transition, unfolding, solids-melting lines, and ultimate maximum-freeze-concentration conditions. The freezing point decreased with the increase of solids; whereas glass transition, unfolding, and solids-melting decreased with the decrease of solids up to solids content 0.84g\\/g gelatin and then remained constant. The freezing point, glass transition and solids-melting

Mohammad Shafiur Rahman; Ghalib Al-Saidi; Nejib Guizani; Aminah Abdullah

2010-01-01

148

Measurements of Heat Capacity and Enthalpy of Phase Change Materials by Adiabatic Scanning Calorimetry  

NASA Astrophysics Data System (ADS)

Phase change materials (PCMs) are substances exhibiting phase transitions with large latent heats that can be used as thermal storage materials with a large energy storage capacity in a relatively narrow temperature range. In many practical applications the solid-liquid phase change is used. For applications accurate knowledge of different thermal parameters has to be available. In particular, the temperature dependence of the enthalpy around the phase transition has to be known with good accuracy. Usually, the phase transitions of PCMs are investigated with differential scanning calorimetry (DSC) at fast dynamic scanning rates resulting in the effective heat capacity from which the (total) heat of transition can be determined. Here we present adiabatic scanning calorimetry (ASC) as an alternative approach to arrive simultaneously at the equilibrium enthalpy curve and at the heat capacity. The applicability of ASC is illustrated with measurements on paraffin-based PCMs and on a salt hydrate PCM.

Losada-Pérez, Patricia; Tripathi, Chandra Shekhar Pati; Leys, Jan; Cordoyiannis, George; Glorieux, Christ; Thoen, Jan

2011-05-01

149

Quantitative Thermal Analysis of Poly(butylene Terephthalate) by Temperature-Modulated Differential Scanning Calorimetry  

NASA Astrophysics Data System (ADS)

Quantitative thermal analysis is performed on poly(butylene terephthalate), PBT, between 5 and 600 K based on the measured heat capacity by adiabatic calorimertry, standard differential scanning calorimetry (DSC) and temperature-modulated differential scanning calorimetry (TMDSC). Based on the new data, the low temperature heat capacity is linked to the vibrational spectrum, using the ATHAS method to calculate the solid heat capacity of PBT. Using the solid and liquid heat capacities as reference, quenched and semicrystalline PBT are examined. The quenched PBT shows two glass transition temperatures (Tg) on heating at around 248 K and 311 K. The semicrystalline PBT has only one Tg at around 311 K and both are compared with earlier results. Using TMDSC, the apparent reversing and nonreversing heat capacities are separated between glass and melting temperatures. With these data one can compute crystallinity changes with temperature, the mobile amorphous fractions and rigid amorphous fractions.

Pyda, M.; Nowak-Pyda, E.; Wunderlich, B.

2004-03-01

150

Dijet mass resolution and compensating calorimetry  

SciTech Connect

The calorimetry for SSC detectors has as its role the detection of the basic particles of the Standard Model. Those germane to calorimetry are quarks, photons, electrons, and gluons. Note that all the hadronic entities appear in the calorimetry as jets. The detection of single hadrons belongs to a past era when quark molecules'' were the focus of intense study. Thus, the goal of calorimetry at the SSC must be the study of jets. In particular, one must understand what defines the limits of accuracy of the jets. If there are intrinsic physical processes which limit the precision of jet measurements, then calorimetry which is more accurate is unnecessary if not wasteful. 5 refs., 5 figs.

Green, D.

1991-05-01

151

Comparison of Calorimetry: MIT and Fleischmann-Pons Systems  

NASA Astrophysics Data System (ADS)

The history of cold fusion shows that the MIT heat conduction calorimetry in 1990 reported a sensitivity of 40 mW while the Fleischmann-Pons Dewar calorimetry achieved a sensitivity of 0.1 mW. Additional information about the MIT calorimetry allows a more detailed analysis. The major finding is that the MIT calorimetric cell was so well insulated with glass wool (2.5 cm in thickness) that the major heat transport pathway was out of the cell top rather than from the cell into the constant temperature water bath. It can be shown for the MIT calorimeter that 58% of the heat transport was through the cell top and 42% was from the cell into the water bath. Analysis of the Fleischmann-Pons Dewar cell shows that under conditions similar to the MIT experiments, almost all of the heat flow would be from the Dewar calorimetric cell to the constant temperature water bath. Furthermore, the sensitivity of the Fleischmann- Pons temperature measurements was 0.001 K versus 0.1 K for the MIT calorimetric cell. Evaluations of the calorimetric equations and data analysis methods leads to the conclusion that the Fleischmann-Pons calorimetry was far superior to that of MIT.

Miles, Melvin H.; Hagelstein, Peter

2011-03-01

152

DSC Deconvolution of the Structural Complexity of c-MYC P1 Promoter G-Quadruplexes  

PubMed Central

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

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

2011-01-01

153

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

SciTech Connect

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

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

2008-02-26

154

A "release" protocol for isothermal titration calorimetry.  

PubMed Central

Isothermal titration calorimetry (ITC) has become a standard method for investigating the binding of ligands to receptor molecules or the partitioning of solutes between water and lipid vesicles. Accordingly, solutes are mixed with membranes (or ligands with receptors), and the subsequent heats of incorporation (or binding) are measured. In this paper we derive a general formula for modeling ITC titration heats in both binding and partitioning systems that allows for the modeling of the classic incorporation or binding protocols, as well as of new protocols assessing the release of solute from previously solute-loaded vesicles (or the dissociation of ligand/receptor complexes) upon dilution. One major advantage of a simultaneous application of the incorporation/binding and release protocols is that it allows for the determination of whether a ligand is able to access the vesicle interior within the time scale of the ITC experiment. This information cannot be obtained from a classical partitioning experiment, but it must be known to determine the partition coefficient (or binding constant and stochiometry) and the transfer enthalpy. The approach is presented using the partitioning of the nonionic detergent C12EO7 to palmitoyloleoylphosphatidylcholine vesicles. The release protocol could also be advantageous in the case of receptors that are more stable in the ligand-saturated rather than the ligand-depleted state.

Heerklotz, H H; Binder, H; Epand, R M

1999-01-01

155

Accurate measurement of heat capacity by differential scanning calorimetry  

NASA Technical Reports Server (NTRS)

Experience with high quality heat capacity measurement by differential scanning calorimetry is summarized and illustrated, pointing out three major causes of error: (1) incompatible thermal histories of the sample, reference and blank runs; (2) unstable initial and final isotherms; (3) incompatible differences between initial and final isotherm amplitudes for sample, reference and blank runs. Considering these problems, it is shown for the case of polyoxymethylene that accuracies in heat capacity of 0.1 percent may be possible.

1984-01-01

156

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

Code of Federal Regulations, 2010 CFR

...2010-10-01 false Digital selective calling (DSC) operating procedures. 80.103 Section...80.103 Digital selective calling (DSC) operating procedures. (a) Operating procedures for the use of DSC equipment in the maritime mobile...

2010-10-01

157

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

Code of Federal Regulations, 2010 CFR

...Frequencies for digital selective calling (DSC). 80.359 Section 80.359 Telecommunication...Frequencies for digital selective calling (DSC). (a) General purpose calling. ...ship and coast stations for general purpose DSC. There are three series of...

2010-10-01

158

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

Code of Federal Regulations, 2010 CFR

...2009-10-01 false Digital selective calling (DSC) operating procedures. 80.103 Section...80.103 Digital selective calling (DSC) operating procedures. (a) Operating procedures for the use of DSC equipment in the maritime mobile...

2009-10-01

159

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

Code of Federal Regulations, 2010 CFR

...Frequencies for digital selective calling (DSC). 80.359 Section 80.359 Telecommunication...Frequencies for digital selective calling (DSC). (a) General purpose calling. ...ship and coast stations for general purpose DSC. There are three series of...

2009-10-01

160

A study of mercuric iodide near melting using differential scanning calorimetry, Raman spectroscopy and X-ray diffraction  

NASA Astrophysics Data System (ADS)

High-temperature studies of mercuric iodide (HgI2) involving differential scanning calorimetry (DSC), Raman spectroscopy and X-ray powder diffraction have failed to confirm the existence of a red-colored tetragonal high-temperature phase called ?'-HgI2 reported by S.N. Toubektsis et al. [J. Appl. Phys. 58 (1988) 2070] using DSC measurements. The multiple DSC peaks near melting reported by Toubektsis are found by the present authors only if the sample is heated in a stainless-steel container. Using a Pyrex container or inserting a platinum foil between the HgI2 and the stainless-steel container yields only one sharp, single DSC peak at the melting point. The nonexistence of the ?' phase is confirmed by high-temperature X-ray diffraction and Raman spectroscopy performed in the vicinity of the melting point. These methods clearly, indicate the existence of only the yellow orthorhombic ?-HgI2 phase. The experimental high-temperature DSC, Raman and X-ray diffraction data are presented and discussed.

Burger, A.; Morgan, S.; Jiang, H.; Silberman, E.; Schieber, M.; Van Den Berg, L.; Keller, L.; Wagner, C. N. J.

1989-11-01

161

Automatic calorimetry system monitors RF power  

NASA Technical Reports Server (NTRS)

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.

Harness, B. W.; Heiberger, E. C.

1969-01-01

162

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

PubMed

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

Mazurek-Wado?kowska, Edyta; Winnicka, Katarzyna; Czajkowska-Ko?nik, Anna; Czyzewska, Urszula; Miltyk, Wojciech

2013-01-01

163

Polarization as a Tool in Calorimetry  

NASA Astrophysics Data System (ADS)

The signals from a high-Z scintillating crystal (BSO) are studied to characterize Cherenkov light polarization and to measure the longitudinal polarization profile of Cherenkov light in electromagnetic showers. The scintillation and Cherenkov lights can be separated by making use of the fact that the latter is polarized in the context of dual-readout calorimetry. In addition, this unique characteristic of Cherenkov light opens up a new set of possibilities that range from high-energy calorimetry to atmospheric air showers.

Akchurin, N.

164

New results in optical fiber Cherenkov calorimetry  

NASA Astrophysics Data System (ADS)

Quartz fiber calorimetry is a sampling calorimetry technique based on the detection of Cherenkov light generated in quartz optical fibers. Optical fibers transport only selected modes of light which results in very narrow visible showers. In addition, this technique is characterized by radiation resistance measured in gigarads and nanosecond pulse duration. The results of recent beam tests are presented, illustrating behavior of electromagnetic calorimeters based on this technique as a function of their absorber type, density and distribution of fibers and fiber types.

Contin, A.; De Salvo, R.; Gorodetzky, P.; Helleboid, J. M.; Johnson, K. F.; Juillot, P.; Lazic, D.; Lundin, M.

1995-12-01

165

Melting by temperature-modulated calorimetry  

SciTech Connect

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

Wunderlich, B.; Okazaki, Iwao; Ishikiriyama, Kazuhiko; Boller, A. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemistry]|[Oak Ridge National Lab., TN (United States)

1997-09-01

166

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

PubMed

A novel, powerful analytical technique, preparative temperature rising elution fractionation (prep TREF)/high-temperature (HT)-HPLC/Fourier transform infrared spectroscopy (FTIR)/high-performance differential scanning calorimetry (HPer DSC)), has been introduced to study the correlation between the polymer chain microstructure and the thermal behaviour of various components in a complex impact polypropylene copolymer (IPC). For the comprehensive analysis of this complex material, in a first step, prep TREF is used to produce less complex but still heterogeneous fractions. These chemically heterogeneous fractions are completely separated by using a highly selective chromatographic separation method--high-temperature solvent gradient HPLC. The detailed structural and thermal analysis of the HPLC fractions was conducted by offline coupling of HT-HPLC with FTIR spectroscopy and a novel DSC method--HPer DSC. Three chemically different components were identified in the mid-elution temperature TREF fractions. For the first component, identified as isotactic polypropylene homopolymer by FTIR, the macromolecular chain length is found to be an important factor affecting the melting and crystallisation behaviour. The second component relates to ethylene-propylene copolymer molecules with varying ethylene monomer distributions and propylene tacticity distributions. For the polyethylene component (last eluting component in all semi-crystalline TREF fractions), it was found that branching produced defects in the long crystallisable ethylene sequences that affected the thermal properties. The different species exhibit distinctively different melting and crystallisation behaviour, as documented by HPer DSC. Using this novel approach of hyphenated techniques, the chain structure and melting and crystallisation behaviour of different components in a complex copolymer were investigated systematically. PMID:23612870

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

2013-11-01

167

Determination of the nateglinide polymorphic purity through DSC.  

PubMed

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

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

2011-04-01

168

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

NASA Astrophysics Data System (ADS)

Electrical conductivity, differential scanning calorimetry (DSC) and 7Li nuclear magnetic resonance (NMR) studies have been carried out on liquid electrolytes such as ethylene carbonate:propylene carbonate (EC:PC) and EC:dimethyl carbonate (DMC) containing LiPF 6 (and LiCF 3SO 3 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 measurements were carried out at atmospheric pressure from room temperature to about -150°C and the electrical conductivity studies were performed at room temperature at pressures up to 0.3 GPa. The liquids and hybrid electrolytes are similar in that the electrical conductivity of the EC:PC-based substances exhibits Vogel-Tammann-Fulcher (VTF) behaviour while that for the EC:DMC-based substances does not. Part of the deviation from VTF behaviour for the EC:DMC-based materials is attributed to crystallization. Further, the glass transition temperatures as determined from NMR, DSC and electrical conductivity measurements are about the same for the liquids and hybrid electrolytes. However, substantial differences are found. The electrical conductivity of the hybrid electrolytes at room temperature is lower than expected and, more importantly, the relative change of conductivity with pressure is larger than for the liquids. In addition, above the glass transition temperature, the NMR T1 values are smaller and the NMR linewidths are larger for the hybrid electrolytes than for the liquids while at both low and high temperature the NMR linewidths are larger. Consequently, it is concluded that significant solid matrix-lithium ion interactions take place.

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

169

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

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

170

Using direct calorimetry to test the accuracy of indirect calorimetry in an ectotherm.  

PubMed

We previously demonstrated that the relationship between respiratory gas exchange and metabolic heat production is unexpectedly variable and that conventional approaches to estimating energy expenditure by indirect calorimetry can incorporate large errors. Prior studies, however, comparing direct and indirect calorimetry of animals focused only on endothermic organisms. Given that endothermy and ectothermy represent a fundamental dichotomy of animal energetics, in this analysis we explore how these contrasting physiologies correlate with the relationship between heat production and respiratory gas exchange. Simultaneous indirect and direct calorimetry in an ectotherm, the ball python (Python regius Shaw), revealed that the relationships between gas exchange and heat production were within 1% of those expected when analyses using indirect calorimetry were based on the assumption that the fasting animal catabolized only protein. This accuracy of indirect calorimetry contrasts sharply with our previous conclusions for three species of birds and mammals. PMID:16826509

Walsberg, Glenn E; Hoffman, Ty C M

2006-01-01

171

DYNAMICS IN POLY(OXYMETHYLENE) AND POLY(OXYMETHYLENE-CO-OXYETHYLENE) AS STUDIED VIA A COMBINED CREEP RATE SPECTROSCOPY\\/DIFFERENTIAL SCANNING CALORIMETRY APPROACH  

Microsoft Academic Search

The peculiarities and kinetics of segmental dynamics in a few semi-crystalline poly(oxymethylene) (POM) samples and in poly(oxymethylene-co-oxyethylene) with 1.5% ethylene oxide units were studied over the temperature range from 110 to 430K. Differential scanning calorimetry (DSC) and laser-interferometric creep rate spectroscopy (CRS) were used. The latter was operated under uniaxial tension or compression. A number of dynamic anomalies were observed.

V. A. Bershtein; L. M. Egorova; V. M. Egorov; N. N. Peschanskaya; P. N. Yakushev; M. Y. Keating; E. A. Flexman; R. J. Kassal; K. P. Schodt

2002-01-01

172

Study of the phase behaviour of fully hydrated saturated diacyl phosphatidylserine\\/fatty acid mixtures with 31P-NMR and calorimetry  

Microsoft Academic Search

We investigated the phase behaviour of saturated phosphatidylserine\\/fatty acid mixtures in excess water and at acidic pH with 31P-NMR and differential scanning calorimetry (DSC). The pure PS in excess water yielded a bilayer structure over a large temperature range. The chain-melting transition temperature for the pure PS system increased with decreasing pH. In the acidic environment, the PS displays a

Zhi Huang; Richard M Epand

1997-01-01

173

Direct correlations between mechanical-relaxation measurements. Differential-scanning-calorimetry data, and thermally stimulated charge-decay results from Teflon-FEP electrets  

Microsoft Academic Search

Commercial Teflon-FEP films from DuPont were studied by means of several different techniques: The complex shear modulus was measured with a torsion pendulum at 1 Hz between -180 and +260°C; the complex dielectric permittivity was studied between 100 Hz and 1 MHz from -150 to +300°C; differential scanning calorimetry (DSC) was used to determine the phase transitions in the temperature

Wolfgang STARK; Reimund GERHARD-MULTHAUPT

1994-01-01

174

Ordered structures and progressive transesterification in PC\\/PBT melt blends studied by FT i.r. spectroscopy combined with d.s.c. and n.m.r  

Microsoft Academic Search

Melt blends of polycarbonate (PC) and poly(butylene terephthalate) (PBT) were characterized by their transesterification and crystallization behaviour using Fourier transform infrared spectroscopy (FT i.r.) as well as nuclear magnetic resonance (n.m.r.) spectroscopy and differential scanning calorimetry (d.s.c.). The transesterification can be analysed by FT i.r. spectroscopy using two different spectral features. The appearance of new bands is used for the

I. Hopfe; G. Pompe; K.-J. Eichhorn

1997-01-01

175

Dehydration\\/recrystallization mechanisms, energetics, and kinetics of hydrated calcium silicate minerals: an in situ TGA\\/DSC and synchrotron radiation SAXS\\/WAXS study  

Microsoft Academic Search

The dehydration and recrystallization of the natural hydrated calcium silicates xonotlite [Ca6Si6O17(OH)2], 11Å anomalous tobermorite [Ca5Si6O16(OH)2·4H2O], and hillebrandite [Ca2SiO3(OH)2] were studied in situ by dynamic heating (5°C min?1) differential scanning calorimetry\\/thermogravimetric analysis (TGA\\/DSC) and synchrotron small- and wide-angle X-ray scattering (SAXS\\/WAXS). All have structures based on silicate chains with a repeat unit of three tetrahedra (‘dreierketten’). Room-T infrared data for

S Shaw; C. M. B Henderson; B. U Komanschek

2000-01-01

176

Thermokineticmodel simulations for methyl ethyl ketone peroxide contaminated with H 2 SO 4 OR NaOH by DSC and VSP2  

Microsoft Academic Search

In\\u000a this study, a mixture of methyl ethyl ketone peroxide (MEKPO) with various\\u000a contaminants, such as H2SO4\\u000a and NaOH, was prepared in order to elucidate the cause of these accidents\\u000a and the results of upset conditions. Thermokinetic parameters were acquired\\u000a by both differential scanning calorimetry (DSC) and vent sizing package 2\\u000a (VSP2). In addition, we simulated the thermokinetic parameters and

R. H. Chang; J. M. Tseng; J. M. Jehng; C. M. Shu; H. Y. Hou

2006-01-01

177

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

PubMed

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

Dachs, Edgar; Benisek, Artur

2011-08-01

178

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

PubMed Central

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.

Dachs, Edgar; Benisek, Artur

2011-01-01

179

High temperature drop calorimetry and thermodynamic properties  

SciTech Connect

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.

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

180

Study of dioxolane-dioxepane copolymers through IR and DSC  

Microsoft Academic Search

SummaryThe composition of the copolymers of 1,3-dioxolane with 1,3-dioxepane was investigated using FT-IR and DSC. The first method produce accurate values for the overall composition, the later allows discriminating between the copolymer and the mixture of homopolymers.

Dumitru-Mircea Vuluga; Magdalena Pantiru; Thierry Hamaide; Dan Sorin Vasilescu

2004-01-01

181

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

NASA Astrophysics Data System (ADS)

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

Cie?la, K.; Eliasson, A. C.

2007-12-01

182

One-step simultaneous differential scanning calorimetry-FTIR microspectroscopy to quickly detect continuous pathways in the solid-state glucose/asparagine Maillard reaction.  

PubMed

The stepwise reaction pathway of the solid-state Maillard reaction between glucose (Glc) and asparagine (Asn) was investigated using simultaneous differential scanning calorimetry (DSC)-FTIR microspectroscopy. The color change and FTIR spectra of Glc-Asn physical mixtures (molar ratio = 1:1) preheated to different temperatures followed by cooling were also examined. The successive reaction products such as Schiff base intermediate, Amadori product, and decarboxylated Amadori product in the solid-state Glc-Asn Maillard reaction were first simultaneously evidenced by this unique DSC-FTIR microspectroscopy. The color changed from white to yellow-brown to dark brown, and appearance of new IR peaks confirmed the formation of Maillard reaction products. The present study clearly indicates that this unique DSC-FTIR technique not only accelerates but also detects precursors and products of the Maillard reaction in real time. PMID:24645515

Hwang, Deng-Fwu; Hsieh, Tzu-Feng; Lin, Shan-Yang

2013-01-01

183

Apparent Thermal Properties of Phase-Change Materials: An Analysis Using Differential Scanning Calorimetry and Impulse Method  

NASA Astrophysics Data System (ADS)

Thermal properties of newly developed plaster based on hydrated lime, metakaolin, and paraffinic wax enclosed in polymer micro-capsules are studied in the article. At first, differential scanning calorimetry (DSC) is applied on Micronal PCM capsules for determination of the temperature interval of thawing and solidification. Then, the initial temperature of the phase change and specific heat capacity of the plaster are measured by DSC. The thermal conductivity and thermal diffusivity are determined by an impulse method. For comparative reasons, the properties of lime-based plaster without PCM are studied as well. The obtained results demonstrate the enhanced heat storage capacity of the studied material that can be used for application in lightweight building envelope systems.

Pavlík, Zbyšek; Trník, Anton; Ondruška, Ján; Keppert, Martin; Pavlíková, Milena; Volfová, Petra; Kaulich, Viktor; ?erný, Robert

2013-05-01

184

Differential scanning calorimetry analysis of the linear parabolic growth of nanometric Ni silicide thin films on a Si substrate  

NASA Astrophysics Data System (ADS)

The formation of nanometric Ni silicide films on a Si wafer is analyzed using differential scanning calorimetry (DSC) and isothermal x-ray diffraction measurements. The sensitivity of DSC is remarkable even in this experimental configuration constituted of a Ni/Si bilayer deposited on a Si substrate. Both methods confirm the sequential growth of Ni2Si and NiSi (for T<700 °C). However the kinetics of growth of the first silicide formed (Ni2Si) cannot be fitted, for the two sets of measurements, by a simple parabolic law. Better agreement is obtained using a linear-parabolic growth law and a smaller activation energy for the linear term (0.8 eV) than for the parabolic one (1.5 eV).

Nemouchi, F.; Mangelinck, D.; Bergman, C.; Gas, P.; Smith, Ulf

2005-01-01

185

A differential scanning calorimetry study of phosphocholines mixed with paclitaxel and its bromoacylated taxanes.  

PubMed

High sensitivity differential scanning calorimetry (DSC) was used to investigate the thermotropic phase properties of binary mixtures of disaturated phosphocholines (PCs) and alpha-bromoacyl taxane derivatives. The alpha-bromoacyl taxanes were synthesized as hydrolyzable hydrophobic prodrugs of paclitaxel. The PCs used were 1, 2-dimyristoyl-sn-glycero-3-phosphatidyl-choline (DMPC), 1, 2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) and 1, 2-distearoyl-sn-glycero-3-phosphatidylcholine (DSPC). The bromoacyl chain lengths of the taxane prodrugs were varied from 6 to 12 or 16 carbons. For comparison, paclitaxel and PC mixtures were also examined. DSC data from DPPC and bromoacyl taxane mixtures showed a complete abolition of the pretransition and significant broadening of the main phase transition with increasing amounts of bromoacyl taxane prodrugs. The effects were more pronounced with the long-chain compared to the short-chain prodrugs. Under equivalent DSC conditions, the short-chain DMPC showed greater changes in thermotropic phase behavior than with DPPC on taxane addition, suggesting an enhanced degree of association with the fluid-type bilayers. Under similar conditions, the long-chain DSPC bilayers showed a far less significant change in phase behavior on taxane addition than DPPC. These changes were also chain length-dependent for both the PCs and the taxane prodrugs. In contrast, PC and paclitaxel (lacking the acyl chain) mixtures under similar conditions showed insignificant changes in the endotherms, suggesting only slight insertion of the molecule into the PC bilayers. From the DSC data it is apparent that taxane prodrugs solvated in DMPC bilayers more than in DPPC and DSPC bilayers, and taxane prodrugs with longer acyl chains were able to associate with PCs better than those with shorter chain prodrugs. DSC data also suggest that paclitaxel was poorly associated with any of the PCs. In general, the amount of taxane association with bilayers decreased in order: DMPC > DPPC > DSPC. In contrast, the transition enthalpy (DeltaH) of DMPC, DPPC, and DSPC mixtures with paclitaxel showed significantly lower enthalpies than with taxane prodrugs. Taken together, the DSC data suggest that the acyl chains of paclitaxel prodrugs have some access into the bilayers via alignment with the acyl chain of the PC component. PMID:10620289

Ali, S; Minchey, S; Janoff, A; Mayhew, E

2000-01-01

186

Liquid Argon Calorimetry for ATLAS  

NASA Astrophysics Data System (ADS)

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.

Robinson, Alan

2008-05-01

187

Calorimetry of the Rice Detector  

NASA Astrophysics Data System (ADS)

Radio Ice Cherenkov Experiment (RICE) is an ultrahigh-energy (UHE) cosmic ray neutrino detector for neutrino energies greater than a PeV. This pilot project explores the radio detection technique for UHE particles. Deployed at the Antarctic polar ice cap, RICE antennas have been operational since 1996. Basic calibrations of the antenna array have been done using data taken mostly in situ. The calibration results and an upper limit on electron neutrino flux based on one month of analyzed data are reported here.

Razzaque, Soebur

2002-01-01

188

Calculation of Temperature Rise in Calorimetry.  

ERIC Educational Resources Information Center

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)

Canagaratna, Sebastian G.; Witt, Jerry

1988-01-01

189

Isothermal Titration Calorimetry in the Student Laboratory  

ERIC Educational Resources Information Center

Isothermal titration calorimetry (ITC) is the measurement of the heat produced by the stepwise addition of one substance to another. It is a common experimental technique, for example, in pharmaceutical science, to measure equilibrium constants and reaction enthalpies. We describe a stirring device and an injection pump that can be used with a…

Wadso, Lars; Li, Yujing; Li, Xi

2011-01-01

190

Electromagnetic Calorimetry Using Scintillating Plastic Fibres.  

National Technical Information Service (NTIS)

When used in lead-scintillator sandwich calorimetry, scintillating optical fibers offer a new way to achieve fine grain sampling and hereby to improve the energy and spatial resolution of a technique still unbeaten for timing and compactness. A small calo...

H. Burmeister P. Sonderegger J. M. Gago A. Maio M. Pimenta

1983-01-01

191

Applications of Isothermal Titration Calorimetry in RNA Biochemistry and Biophysics  

PubMed Central

Isothermal titration calorimetry (ITC) has been applied to the study of proteins for many years. Its use in the biophysical analysis of RNAs has lagged significantly behind its use in protein biochemistry, however, in part because of the relatively large samples required. As the instrumentation has become more sensitive, the ability to obtain high quality data on RNA folding and RNA ligand interactions has improved dramatically. This review provides an overview of the ITC experiment and describes recent work on RNA systems that have taken advantage of its versatility for the study of small molecule binding, protein binding, and the analysis of RNA folding.

Feig, Andrew L.

2008-01-01

192

Neutral-beam aiming and calorimetry for MFTF-B  

SciTech Connect

The vessel for the Tandem Mirror Fusion Test Facility (MFTF-B) will have up to eleven 0.5-s-duration neutral-beam injectors for the initial heating of the MFTF-B plasma. Knowing the exact alignment of the beams and their total power is critical to the performance of the experiment. Using prototype aiming and calorimetry systems on the High Voltage Test Stand (HVTS) at Lawrence Livermore National Laboratory (LLNL), we hope to prove our ability to obtain an aiming accuracy of +-1 cm at the plasma and a calorimetric accuracy of +-5% of the actual total beam energy.

Goldner, A.I.; Margolies, D.

1981-01-01

193

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

Microsoft Academic Search

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

I. Chakarska; S. Todinova; K. Idakieva

2010-01-01

194

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

NASA Astrophysics Data System (ADS)

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.

Dan, Kaustabh; Roy, Madhusudan; Datta, Alokmay

2014-04-01

195

DSC solution forow in a staggered double lid driven cavity  

Microsoft Academic Search

SUMMARY A benchmark quality solution is presented forow in a staggered double lid driven cavity obtained by using the wavelet-based discrete singular convolution (DSC). The proposed wavelet based algo- rithm combines local methods' ?exibility and global methods' accuracy, and hence, is a promising ap- proach for achieving the high accuracy solution of the Navier-Stokes equations. Block structured grids with pseudo-overlapping

Y. C. Zhou; B. S. V. Patnaik; D. C. Wan; G. W. Wei

196

Assignment of DSC thermograms of wood and its components  

Microsoft Academic Search

Exotherms in the DSC analysis of wood and its components have been assigned using Akamatsu wood (Pinus densiflora). Analysis of wood powder indicated two exotherms at around 340 and 475°C. Among isolated components galactoglucomannan has a single exotherm at around 330–360°C, and other commercial amorphous polysaccharides are in the range of 300–370°C. Therefore, the transition at around 340°C in wood

Sho-ichi Tsujiyama; Atsuko Miyamori

2000-01-01

197

TMA, DMA, DSC, and TGA of lead free solders  

Microsoft Academic Search

Most of the electronics packaging materials, especially solders are temperature dependent. Their temperature-dependent material properties can be obtained by TMA (thermal mechanical analysis), DMA (dynamic mechanical analysis), DSC (differential scanning calorimeter), and TGA (thermogravimetric analysis). In this study, the thermal coefficient of expansion (TCE), storage modulus, moisture uptake, and melting point of two lead free solders, 96.5wt%Sn-3.5wt%Ag and 42wt%Sn-58wt%Bi provided

John H. Lau; Chris Chang

1998-01-01

198

Mineralogical Applications of High-Temperature Reaction Calorimetry.  

National Technical Information Service (NTIS)

Mineralogical applications of high-temperature calorimetry may involve either (a) direct combination and transformation work, or (b) solution calorimetry. Among these approaches the latter is the more generally useful. A crucial problem in high-temperatur...

O. J. Kleppa

1976-01-01

199

Investigation of thermal-oxidative stability of esters by means of differential scanning calorimetry  

SciTech Connect

The methods in existence for the determination of the thermal-oxidative stability of lubricants are insensitive. Differential scanning calorimetry (DSC) is recommended. It measures the differential thermal energy required to maintain a test sample temperature at the same level as a standard sample. As energy supplied to the standard or test sample is equivalent to energy absorbed or released by the sample, direct measure of thermal energy is registered. In this study, esters for dispersion media of grease manufacturing are sampled: pentaerythritol ester (PET), dioctyl ester of sebacic acid (DOS), and a variation OS. Perflourinated acyclic polyethyls are also tested by thermogravimetric analysis. Of all tested esters, the perflouropolyethyls PEF-20 and PEF-320 had the highest thermal oxidation stability.

Nikonorov, E.M.; Ataeva, O.V.; Petrova, L.N.; Sazonova, N.S.

1983-05-01

200

Low-Temperature Differential Scanning Calorimetry of an Al-Mg-Si Alloy  

NASA Astrophysics Data System (ADS)

The clustering behavior at room temperature of a pure ternary Al-0.59 wt pct Mg-0.82 wt pct Si alloy was investigated by low-temperature differential scanning calorimetry (DSC). We find three clustering reactions that take place in two stages. The first two reactions are linked to each other and are completed after 1 hour. The third reaction starts around 1 hour after quenching and is completed after 2 weeks. Only the latter reaction exhibits a strong shift of the peak position of the thermal signal, indicating a change in the activation energy during aging at room temperature caused by changing solute supersaturation or increasing trapping of vacancies. The first two stages are closely linked to the known adverse effect of room-temperature preaging on the ensuing age-hardening step, since 60 to 80 pct of cluster formation is sufficient to establish the full negative effect.

Chang, C. S. T.; Banhart, J.

2011-07-01

201

CDF (Collider Detector at Fermilab) calorimetry  

SciTech Connect

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.

Jensen, H.B.

1987-03-01

202

Overabundance of carbon monoxide in calorimetry tests  

SciTech Connect

The amount of carbon monoxide recovered from calorimetry tests of high explosives is far larger than the amount predicted by equilibrium calculations. The present kinetics study of PETN [(nitro(oxy)methyl]-propanediol dinitrate) has revealed that the cooling of the calorimetry bomb after detonation of a PETN sample sufficiently slows those reactions that would otherwise lead to equilibrium so that these reactions are effectively frozen in the time scale of recovery of detonation products. Among these reactions, those that can create CH{sub 4} are the most important ones. Their rates are generally slow at all temperatures relevant to calorimetry tests. This and the slowing down of a reaction, CO + H{sub 2}O {yields} H{sub 2} + CO{sub 2} at temperatures below 1500 K are the main caus of the freeze-out of CO. A possible slow rate of the soot formation (i.e., condensed carbon) is not responsible for it. The sensitivity of the present result to the cooling rate of the detonation products and to free radicals is also examined. 10 refs., 5 figs., 2 tabs.

Ree, F.H.; Pitz, W.J.; Thiel, M. van; Souers, P.C. [Lawrence Livermore National Lab., CA (United States)] [Lawrence Livermore National Lab., CA (United States)

1996-04-04

203

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

204

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

PubMed

Detonation nanodiamond (ND) is a suitable source material to produce unique samples consisting of almost uniform diamond nanocrystals (d = 3-5 nm). Such samples exist in the form of long stable aqueous dispersions with narrow size distribution of diamond particles. The material is finding ever increasing application in biomedicine. The major problem in producing monodispersed diamond colloids lies in the necessity of deagglomeration of detonation soot and/or removing of clusters formed by already isolated core particles in dry powders. To do this one must have an effective method to monitor the aggregation state or dispersity of powders and gels prior to the preparation of aqueous dispersions. In the absence of dispersity control at various stages of preparation the reproducibility of properties of existing ND materials is poor. In this paper we introduce differential scanning calorimetry (DSC) as a new tool capable to distinguish the state of aggregation in dry and wetted ND materials and to follow changes in this state under different types of treatment. Samples with identical X-ray diffraction patterns (XRD) and high resolution transmission electron microscopy (HRTEM) images gave visibly different DSC traces. Strong correlation was found between dynamic light scattering (DLS) data for colloids and DSC parameters for gels and powders of the same material. Based on DSC data we improved dispersity of existing ND materials and isolated samples with the best possible DSC parameters. These were true monodispersed easily dispersible fractions of ND particles with diameters of ca. 3 nm. PMID:23314800

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

2013-02-21

205

Mass fractal characteristics of wet sonogels as determined by small-angle x-ray scattering and differential scanning calorimetry  

SciTech Connect

Low density silica sonogels were prepared from acid sonohydrolysis of tetraethoxysilane. Wet gels were studied by small-angle x-ray scattering (SAXS) and differential scanning calorimetry (DSC). The DSC tests were carried out under a heating rate of 2 deg. C/min from -120 deg. C up to 30 deg. C. Aerogels were obtained by CO{sub 2} supercritical extraction and characterized by nitrogen adsorption and SAXS. The DSC thermogram displays two distinct endothermic peaks. The first, a broad peak extending from about -80 deg. C up to practically 0 deg. C, was associated to the melting of ice nanocrystals with a crystal size distribution with 'pore' diameter ranging from 1 or 2 nm up to about 60 nm, as estimated from Thomson's equation. The second, a sharp peak with onset temperature close to 0 deg. C, was attributed to the melting of macroscopic crystals. The DSC incremental 'nanopore' volume distribution is in reasonable agreement with the incremental pore volume distribution of the aerogel as determined from nitrogen adsorption. No macroporosity was detected by nitrogen adsorption, probably because the adsorption method applies stress on the sample during measurement, leading to a underestimation of pore volume, or because often positive curvature of the solid surface is in aerogels, making the nitrogen condensation more difficult. According to the SAXS results, the solid network of the wet gels behaves as a mass fractal structure with mass fractal dimension D=2.20{+-}0.01 in a characteristic length scale below {xi}=7.9{+-}0.1 nm. The mass fractal characteristics of the wet gels have also been probed from DSC data by means of an earlier applied modeling for generation of a mass fractal from the incremental ''pore'' volume distribution curves. The results are shown to be in interesting agreement with the results from SAXS.

Vollet, D. R.; Donatti, D. A.; Ibanez Ruiz, A.; Gatto, F. R. [Departamento de Fisica, Unesp-Univerisdade Estadual Paulista, IGCE, P.O. Box 178 CEP 13500-970 Rio Claro, SP (Brazil)

2006-07-01

206

Implementation of DSC model and application for analysis of field pile tests under cyclic loading  

Microsoft Academic Search

The disturbed state concept (DSC) model, and a new and simplified procedure for unloading and reloading behavior are implemented in a nonlinear finite element procedure for dynamic analysis for coupled response of saturated porous materials. The DSC model is used to characterize the cyclic behavior of saturated clays and clay-steel interfaces. In the DSC, the relative intact (RI) behavior is

Changming Shao; Chandra S. Desai

2000-01-01

207

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

Code of Federal Regulations, 2010 CFR

...2009-01-01 2009-01-01 false TIER, DSC, OTIER and ODSC requirements. 1710...and Basic Policies § 1710.114 TIER, DSC, OTIER and ODSC requirements. (a...or average basis, are a TIER of 1.25, DSC of 1.25, OTIER of 1.1, and ODSC...

2009-01-01

208

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

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false TIER, DSC, OTIER and ODSC requirements. 1710...and Basic Policies § 1710.114 TIER, DSC, OTIER and ODSC requirements. (a...or average basis, are a TIER of 1.25, DSC of 1.25, OTIER of 1.1, and ODSC...

2010-01-01

209

Assessment of fluidity of different invasomes by electron spin resonance and differential scanning calorimetry.  

PubMed

The aim of this study was to investigate the influence of membrane-softening components (terpenes/terpene mixtures, ethanol) on fluidity of phospholipid membranes in invasomes, which contain besides phosphatidylcholine and water, also ethanol and terpenes. Also mTHPC was incorporated into invasomes in order to study its molecular interaction with phospholipids in vesicular membranes. Fluidity of bilayers was investigated by electron spin resonance (ESR) using spin labels 5- and 16-doxyl stearic acid and by differential scanning calorimetry (DSC). Addition of 1% of a single terpene/terpene mixture led to significant fluidity increase around the C16 atom of phospholipid acyl chains comprising the vesicles. However, it was not possible to differentiate between the influences of single terpenes or terpene mixtures. Incorporation of mTHPC into the bilayer of vesicles decreased fluidity near the C16 atom of acyl chains, indicating its localization in the inner hydrophobic zone of bilayers. These results are in agreement with DSC measurements, which showed that terpenes increased fluidity of bilayers, while mTHPC decreased fluidity. Thus, invasomes represent vesicles with very high membrane fluidity. However, no direct correlation between fluidity of invasomes and their penetration enhancing ability was found, indicating that besides fluidity also other phenomena might be responsible for improved skin delivery of mTHPC. PMID:21527323

Dragicevic-Curic, Nina; Friedrich, Manfred; Petersen, Silvia; Scheglmann, Dietrich; Douroumis, Dennis; Plass, Winfried; Fahr, Alfred

2011-06-30

210

Protein Unfolding Coupled to Ligand Binding: Differential Scanning Calorimetry Simulation Approach  

NASA Astrophysics Data System (ADS)

The aim of this work is to present the physicochemical basis underlying the changes in protein thermostability upon ligand binding. The article is addressed to advanced undergraduate and postgraduate chemistry students with an interest in protein biophysics. In addition, this article provides a useful tool for both learning and teaching biophysics because it links fundamental concepts: thermodynamics, chemical equilibrium, and protein stability. The influence of protein ligand interactions on thermally-induced protein denaturation was monitored by differential scanning calorimetry (DSC). The changes in DSC output (thermogram) emerge by linking binding equilibrium with reversible protein unfolding thermodynamics. We derive the formalism for the description of protein unfolding in the presence of ligand that can bind to a single site on either native, unfolded, or both protein states. In addition to a rigorous mathematical description of the involved equilibria, the model provides the general formulation for simulating thermograms and calculating the changes in protein species during heating. First, we describe ligand interaction and emphasize the relationship between protein stability parameters and redistribution of species in equilibrium. After that, we describe the origin of bimodal thermograms, and finally, the effect on thermogram shape of protein concentration at constant ligand/protein mole ratio.

Soledad Celej, María; Fidelio, Gerardo Daniel; Dassie, Sergio Alberto

2005-01-01

211

Synergistic interaction of xyloglucan and xanthan investigated by rheology, differential scanning calorimetry, and NMR.  

PubMed

A new synergistic interaction between tamarind seed xyloglucan and xanthan was found and investigated by rheology, differential scanning calorimetry (DSC), and NMR. The effect of the acetyl and pyruvate groups in the side chain in xanthan on the synergistic interaction was also examined. The shear moduli G' and G' ' of the mixture solution of xyloglucan and native (or acetate-free) xanthan increased steeply at around 22 degrees C upon cooling. An exothermic DSC peak appeared at the same temperature. A drastic decrease in the of the acetyl and pyruvate groups of the xanthan side chain was observed from 1H NMR spectra only in the mixture at low temperatures (<25 degrees C). It was found that the pyruvate group is more restricted in the mixture solution compared with the acetyl group. The mixture of xyloglucan and pyruvate-free xanthan showed no synergistic interaction. We concluded that this synergistic interaction is caused by the intermolecular binding between xyloglucan and xanthan, and, in the heterotypic junction zones, the xanthan side chain becomes a new state that is different from both the coil and helix states. PMID:16602742

Kim, Bo-Sook; Takemasa, Makoto; Nishinari, Katsuyoshi

2006-04-01

212

Structure of stratum corneum lipids characterized by FT-Raman spectroscopy and DSC. II. Mixtures of ceramides and saturated fatty acids.  

PubMed

Fourier transform (FT) Raman spectroscopy and differential scanning calorimetry (DSC) were used to study the thermotropic phase behaviour of mixtures of ceramides type IV (CER) and stearic acid (SA). For comparison the melting behaviour of SA was re-examined. The Raman spectra of all mixtures in the solid state show sharp bands associated with trans sequencies of the alkyl chain residues of both lipids. These features demonstrate that the hydrocarbon chains are highly ordered in the mixtures, too. The temperature dependence of the conformationally sensitive bands is used to estimate the degree of order in terms of the relative population of trans and gauche conformations. The DSC heating curves for the mixtures show two endothermic transitions which are typical for eutectic melting. The factor group splitting of the CH2 scissoring mode, arising from the orthorhombic subcell packing of SA, disappears in the course of the eutectic melting of samples with a SA content lower than 90 mol%. Both DSC and Raman spectroscopic studies reveal that CER and SA are immiscible in the solid state. The phase diagram of the system is a simple eutectic type one. The addition of SA to CER shifts the melting temperature of ceramides to lower values. However, though SA is a major component of stratum corneum (SC) it is not efficient enough to increase the fluidity of ceramides. PMID:9353900

Neubert, R; Rettig, W; Wartewig, S; Wegener, M; Wienhold, A

1997-09-24

213

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

PubMed

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

Homer, Stephen; Kelly, Michael; Day, Li

2014-08-01

214

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

Microsoft Academic Search

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

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

2010-01-01

215

Investigation of MSWI fly ash melting characteristic by DSC-DTA  

SciTech Connect

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.

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

216

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

NASA Astrophysics Data System (ADS)

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 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.

Dachs, Edgar; Benisek, Artur

2011-08-01

217

Thermal characterization of Titan's tholins by simultaneous TG-MS, DTA, DSC analysis  

NASA Astrophysics Data System (ADS)

Three samples of Titan's tholins synthesized in laboratory under simulated Titan's conditions and presenting different degrees of exposure to ambient atmosphere have been used to study in detail their thermal behavior using thermogravimetry coupled with a mass spectrometer (TG-MS), differential thermal analysis (DTA) and differential scanning calorimetry (DSC). The degradation of Titan's tholins under inert atmosphere follows a three-step consecutive decomposition: a drying stage (>150 °C) where moisture is desorbed, this stage indicated the high hydrophilicity of the tholins; a second stage, the main pyrolysis stage (150-575 °C) where endothermic decomposition begins releasing mainly ammonia, HCN, acetonitrile, and methane over a broad temperature range. Few other hydrocarbon fragments such as ethylene and propane are released but no cyclic molecules, aliphatic or aromatic, are observed. The last stage (>575 °C) is the carbonization of the material leading to a non-crystalline graphitic residue. The thermal degradation under oxygen atmosphere shows the same stages as in argon, with a shift of the thermogravimetric peaks toward lower temperatures indicating a lower thermal stability. The last stage in this case is an oxidative combustion of the char residue. This research concludes that even if Titan tholins, subjected to air contamination for few minutes to several years (varying with the storage conditions) transform to produce different C/N and C/O ratios and thermal stabilities, they undergo the same thermal degradation phases and products. This suggests that the studied three tholins have a similar main chemical structure which does not alter by the air exposure. We discuss on the possible nature of this structure.

Nna-Mvondo, Delphine; de la Fuente, José L.; Ruiz-Bermejo, Marta; Khare, Bishun; McKay, Christopher P.

2013-09-01

218

Monitoring crystallisation of drugs from fast-dissolving oral films with isothermal calorimetry.  

PubMed

The aim of this study was to evaluate the potential of isothermal calorimetry to monitor and characterize crystallisation in drug-loaded fast-dissolving oral films. Films of polyvinylpyrrolidone (PVP) containing indomethacin were cast into glass ampoules; stability was assessed by monitoring the power changes occurring with time. Three grades of PVP (K10, K25 and K40, where the number multiplied by 1000 gives the average molecular weight) were used. Indomethacin was seen to crystallise from all PVP grades over ca. 24-48 h at two study temperatures (25 and 37 degrees C), as denoted by a large exothermic event. At 25 degrees C the exothermic event was a single peak; at 37 degrees C two peaks were observed. Subsequent analysis of the crystals with differential scanning calorimetry (DSC) and polarized light microscopy determined that the stable gamma-polymorph of indomethacin formed at 25 degrees C while both the gamma- and metastable alpha-polymorphs formed at 37 degrees C. The calorimetric data were converted to relative crystallinity as a function of time and analysed with three crystallisation models (Avrami, Tobin and Urbanovici-Segal) to determine crystallisation kinetics. Of the three models applied the Urbanovici-Segal model best described the data, although this may be because this model contains a term that effectively accounts for deviation from the Avrami model. The rate constants determined were broadly consistent irrespective of the model used. Increasing polymer molecular weight did not generally affect the crystallisation rate, although an increase in temperature did result in a concomitant increase in crystallisation rate. The data suggest that isothermal calorimetry is able to monitor drug crystallisation in polymer films and therefore the technique could be a useful tool for conducting stability assays for fast-dissolving oral medicines. PMID:19596058

Gaisford, Simon; Verma, Amit; Saunders, Mark; Royall, Paul G

2009-10-01

219

Calorimetry Exchange Program, Annual Data Report, 1991  

SciTech Connect

The goals of the Calorimetry Sample Exchange Program are: (1) Discuss measurement differences, (2) Review and improve analytical measurements and methods, (3) Discuss new measurement capabilities, (4) Provide data to DOE on measurement capabilities to evaluate shipper-receiver differences, (5) Provide characterized or standard materials as necessary for exchange participants, (6) Provide a measurement control program for plutonium analysis. A sample of PuO{sub 2} powder is available at each participating site for NDA measurement, including either or both calorimetry and high-resolution gamma-ray spectroscopy, the elements which are typically combined to provide a calorimetric assay of plutonium. The facilities measure the sample as frequently and to the level of precision which they desire, and then submit the data to the Exchange for analysis. Statistical tests are used to evaluate the data and to determine if there are significant differences from accepted values for the exchange 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. 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.

McClelland, T.M.

1991-12-31

220

The dual-readout approach to calorimetry  

NASA Astrophysics Data System (ADS)

Simultaneous detection of the Cherenkov light and scintillation light produced in hadron showers makes it possible to measure the electromagnetic shower fraction event by event and thus eliminate the effects of fluctuations in this fraction, which limit the precision with which hadrons and jets can be detected in calorimeters. In the RD52 (DREAM) project, the possibilities of this dual-readout calorimetry are investigated and optimized. In this talk, the latest results of this project are presented. These results concern the first tests of the partially completed full-scale SuperDREAM fiber calorimeter, which were recently carried out at CERN.

Wigmans, Richard

2013-12-01

221

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

NASA Astrophysics Data System (ADS)

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.

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

2012-04-01

222

Conformational study of globulin from common buckwheat (Fagopyrum esculentum Moench) by Fourier transform infrared spectroscopy and differential scanning calorimetry.  

PubMed

Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC) were used to study changes in the conformation of globulin from common buckwheat (Fagopyrum esculentum Moench) (BWG) under various environmental conditions. The IR spectrum of the native BWG showed several major bands from 1691 to 1636 cm(-1) in the amide I' region, and the secondary structure composition was estimated as 34.5% beta-sheets, 20.0% beta-turns, 16.0% alpha-helices, and 14.4% random coils. Highly acidic and alkaline pH conditions induced decreases in beta-sheet and alpha-helical contents, as well as in denaturation temperature (Td) and enthalpy of denaturation (DeltaH), as shown in the DSC thermograms. Addition of chaotropic salts (1.0 M) caused progressive decreases in ordered structures and thermal stability following the lyotropic series of anions. The presence of several protein structure perturbants also led to changes in IR band intensities and DSC thermal stabilities, suggesting protein unfolding. Intermolecular antiparallel beta-sheet (1620 and 1681 cm(-1)) band intensities started to increase when BWG was heated to 90 degrees C, suggesting the initiation of protein aggregation. Increasing the time of the preheat treatment (at 100 degrees C) caused progressive increases in Td and pronounced decreases in DeltaH, suggesting partial denaturation and reassociation of protein molecules. PMID:16190669

Choi, Siu-Mei; Ma, Ching-Yung

2005-10-01

223

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

PubMed Central

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.

White, Sara; Godwin, Harold N.; Weber, Robert J.

2013-01-01

224

Analytic heuristics for a fast DSC-MRI  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

225

Characterizationof supercooling suppression of microencapsulated phase change material byusing DSC  

Microsoft Academic Search

Supercooling suppression of\\u000a microencapsulated n-tetradecane was measured\\u000a using differential scanning calorimetry. Results indicate that the degree\\u000a of supercooling is positively affected by the amount and type of nucleating\\u000a agent present in bulk and microencapsulated n-tetradecane\\u000a which it is used as a phase change material (MPCM). Results also demonstrate\\u000a that the melting point of the n-tetradecane\\u000a is fairly independent of nucleating

J. L. Alvarado; C. Marsh; C. Sohn; M. Vilceus; V. Hock; G. Phetteplace; T. Newell

2006-01-01

226

Combined use of adiabatic calorimetry and heat conduction calorimetry for quantifying propellant cook-off hazards  

Microsoft Academic Search

Recent work performed at DERA (now QinetiQ) has shown how accelerating rate calorimetry (ARC) can be used to obtain time to maximum rate curves using larger samples of energetic materials. The use of larger samples reduces the influence of thermal inertia, permitting experimental data to be gathered at temperatures closer to those likely to be encountered during manufacture, transportation or

P. F. Bunyan; T. T. Griffiths; V. J. Norris

2003-01-01

227

Characterization of molecular interactions using isothermal titration calorimetry.  

PubMed

Isothermal titration calorimetry (ITC) is based on a simple titration of one ligand with another and the small heat changes caused by the molecular interaction are detected. From one ITC experiment the complete set of thermodynamic parameters of binding including association and dissociation constants as well as changes in enthalpy, entropy, and free energy can be derived. Using this technique almost any type of molecular interaction can be analyzed. Both ligands are in solution, and there is no need for their chemical derivatization. There are no limits as to the choice of the analysis buffer, and the analysis temperature can be set between 4 and 80 °C. This technique has been primarily applied to study the interaction between various proteins of Pseudomonas with small molecule ligands. In addition, ITC has been used to study the binding of Pseudomonas proteins to target DNA fragments. PMID:24818906

Krell, Tino; Lacal, Jesús; García-Fontana, Cristina; Silva-Jiménez, Hortencia; Rico-Jiménez, Miriam; Lugo, Andrés Corral; Darias, José Antonio Reyes; Ramos, Juan-Luis

2014-01-01

228

Differential scanning calorimetry study of ordinary Portland cement  

Microsoft Academic Search

The present work involves using differential scanning calorimeter (DSC) in an investigation of the thermal behaviour of hydration products in ordinary Portland cement as a function of age. The two-step loss of water from calcium silicate hydrate, dehydroxylation of calcium hydroxide, and decarbonation of calcium carbonate contribute respectively to the three major endothermic peaks in the DSC curves. Peaks due

W. Sha; E. A. O'Neill; Z. Guo

1999-01-01

229

Progress and new directions in high temperature calorimetry revisited  

Microsoft Academic Search

High temperature reaction calorimetry has seen considerable advances over the past twenty years. New and more sensitive calorimeters,\\u000a improved sample handling techniques, and better control of the final dissolved state has made solution calorimetry and drop\\u000a solution calorimetry, using molten lead borate and other solvents, very versatile and reliable techniques. This paper summarizes\\u000a these advances and presents examples of specific

Alexandra Navrotsky

1997-01-01

230

Calorimetry At Very High Energy Colliders  

SciTech Connect

The capability of hadron colliders has increased to where it will soon be possible to collide protons at center of mass energies of 14 TeV with the advent of the LHC. With increasing collision energy, calorimeters become ever more essential components of a detector, and collaborations often choose very different technologies to meet their goals. From the perspective of a high energy particle and nuclear physicist, a survey is presented of the differences in design considerations and actual performance of the wide variety of calorimeters used in modern hadron colliders such as the Tevatron, RHIC, and LHC. The lessons learned and some ideas for future development of calorimetry will also be discussed.

Chiu, Mickey [Brookhaven National Laboratory, Upton NY 11973 (United States)

2011-06-01

231

Synergies between electromagnetic calorimetry and PET  

SciTech Connect

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.

Moses, William W.

2002-07-30

232

Calorimetry for Fast Authentication of Edible Oils  

NASA Astrophysics Data System (ADS)

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.

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

2009-06-01

233

DSC analysis of post-yield deformed pbt. Effects of thermal history  

Microsoft Academic Search

The effect of the deformation temperature on the energy stored in post-yield deformed poly(butylene terephthalate) PBT, was\\u000a studied by means of DSC tests. Deformed specimens were rapidly cooled after unloading, in order to avoid the energy relaxation\\u000a processes occurring before the DSC measurements. Cooling revealed to have a significant contribution on the whole stored energy,\\u000a as shown by DSC tests

S. Pandini; A. Pegoretti; T. Riccò

2008-01-01

234

THE CALORIMETRY OF COMBUSTIONS AND RELATED REACTIONS: INORGANIC REACTIONS  

Microsoft Academic Search

A review is presented of calorimetric measurements of the heats of ; combustion and other reactions. The precision of the measurements is discussed, ; and possible sources of error in combustion calorimetry are considered. ; Measurement of the heats of formation of the oxides and other compounds is also ; discussed. Recent developments in calorimetry are described briefly, including ;

Holley; C. E. Jr

1962-01-01

235

TG/DSC analysis of Fe{sub 8}(OOH){sub 16}Cl{sub 1.3} nanospindles  

SciTech Connect

The thermal analysis of Fe{sub 8}(OOH){sub 16}Cl{sub 1.3} (Akaganeite-M) nanospindles prepared by the hydrolysis of FeCl{sub 3} solutions are determined by thermogravimetric analyses and differential scanning calorimetry (TG/DSC), in conjunction with field-emission scanning electron microscopy (FE-SEM), and X-ray diffraction (XRD). Different products are formed after Fe{sub 8}(OOH){sub 16}Cl{sub 1.3} nanospindles are calcined at different temperatures for 30 min in N{sub 2} atmosphere: Fe{sub 1.833}(OH){sub 0.5}O{sub 2.5} and magnetite obtained at 250 deg. C; pure magnetite (Fe{sub 3}O{sub 4}) obtained at 630 deg. C; and magnetite containing some iron nitrides (Fe{sub 2}N and Fe{sub 4}N) obtained at 800 deg. C. The calcination of Fe{sub 8}(OOH){sub 16}Cl{sub 1.3} provides a new method to prepare pure magnetite.

Hu Yinghua; Shan Yan [Key Laboratory of Nanomaterials, College of Materials Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Chen Kezheng [Key Laboratory of Nanomaterials, College of Materials Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China)], E-mail: kchen@qust.edu.cn

2008-10-02

236

Physicochemical characterization of silicon-containing glycolipids by DSC, FT-Raman spectroscopy and X-ray diffraction.  

PubMed

Derivatives of dimethylalkylchlorosilanes are novel substances which may be used in formulations for drug targeting. In order to design their properties it is essential to perform physicochemical characterization. For this purpose, a combination of differential scanning calorimetry (DSC), FT-Raman spectroscopy and X-ray diffraction is well suited. For the starting material dimethyloctadecylchlorosilane (DMOC), the assignment of Raman bands is discussed. The influence of sugar-containing head groups on the structures of the hydrocarbon chains of 1-O-(dimethyldodecylsilyl)-[2,3,4,6-tetra-O-acetyl-beta-D-glucopyranoside] and 1-O-(dimethyloctadecylsilyl)-[2,3,4,6-tetra-O-acetyl-beta-D-glucopyranoside] was investigated using the band position of the symmetric methylene mode. The temperature dependence of conformationally sensitive bands in the CH(2)-stretching region (2800-2900 cm(-1)), C-C-stretching region (1000-1150 cm(-1)) and CH(3)-rocking region (830-900 cm(-1)) was studied to characterize the state of order of the alkyl chains. Using X-ray diffraction, the repeating distances of layered structures was determined. The phase transitions occurring were found to be completely reversible. The subcell of DMOC shows an orthorhombic perpendicular packing structure in the crystalline state. PMID:12787939

Uhr, M; Wartewig, S; Unruh, T; Richter, H

2003-06-01

237

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

PubMed Central

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

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

2013-01-01

238

A survey on lossy compression of DSC raw data  

NASA Astrophysics Data System (ADS)

The study investigates the lossy compression of DSC raw data based upon the 12 bit baseline JPEG compression. Computational simulations disclose that JPEG artefacts originate from the quantization of the DCT coefficients. Input noise is shown to serve as an appropriate means to avoid these artefacts. Stimulated by such a noise, the JPEG encoder simply acts as an high frequency noise generator. The processing structure of a general compression model is introduced. The four color planes of an image sensor are separately compressed by a 12 bit baseline JPEG encoder. One-dimensional look-up-tables allow for an optimized adaptation of the JPEG encoder to the noise characteristics of the input signals. An idealized camera model is presumed to be dominated by photon noise. Its noise characteristics can optimally be matched to the JPEG encoder by a common gamma function. The gamma adapted compression model is applied to an exemplary set of six raw images. Its performance concerning the compression ratio and compression noise is examined. Optimally adjusted to the input noise, the compression procedure offers excellent image quality without any perceived loss referring to sharpness or noise. The results show that this method is capable to achieve compression ratios of about factor 4 in practice. The PSNR reaches about 60 dB over the complete signal range.

Fischer, Gregor; Kunz, Dietmar; Köhler, Katja

2008-03-01

239

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

PubMed

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

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

2013-10-01

240

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

NASA Astrophysics Data System (ADS)

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.

Toyran, Neslihan; Severcan, Feride

2007-08-01

241

Differential scanning calorimetry of plant cell walls  

SciTech Connect

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

Lin, Liangshiou; Varner, J.E. (Washington Univ., St. Louis, MO (United States)); Yuen, H.K. (Monsanto Co., St. Louis, MO (United States))

1991-03-15

242

Calorimetry using organic scintillators, 'a sideways perspective'.  

SciTech Connect

Over the last two decades, calorimetry baaed on organic scintillators has developed into an excellent technology for many experimental situations in high energy physics. The primary difficulty, that of extracting the light signals, has benefited from two milestone innovations. The first was the use of wavelength-shifting bars to allow light to be efficiently collected from large areas of scintillator and then readily piped to a readout device. The second of these was the extension of this approach to plastic wavelength-shifting optical fibers whose great flexibility and small diameter allowed a minimum of detector volume to be compromised by the read-out. These two innovations coupled with inventiveness have produced many varied and successful calorimeters. Equal response to both hadronic and electromagnetic showers can be realized in scintillator-based calorimeters. However, in general this is not the case and it is likely that in the search for greater performance, in the future, combined tracking and calorimeter systems will be required.

Proudfoot, J.

1999-09-10

243

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

PubMed

The aim was to quantify the softening effect that two surfactants (C10EO7 and C8G1.6) have on a plant leaf cuticle model wax. Effects on the thermotropic phase behavior and fluidity of the wax (C22H45OH/C32H66/H2O) were determined. The model wax is crystalline at ambient conditions, yet it is clearly softened by the surfactants. Both surfactants decreased the transition temperatures in the wax and the G?/G' ratio of the wax film increased in irreversible steps following surfactant exposure. C10EO7 has a stronger fluidizing effect than C8G1.6 due to stronger interaction with the hydrophobic waxes. Intracuticular waxes (IW) comprise both crystalline and amorphous domains and it has previously been proposed that the fluidizing effects of surfactants are due to interactions with the amorphous parts. New data suggests that this may be a simplification. Surfactants may also absorb in crevices between crystalline domains. This causes an irreversible effect and a softer cuticle wax. PMID:24863760

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

2014-07-15

244

Thermal stability of nanoclay polypropylene composites by simultaneous DSC and TGA  

Microsoft Academic Search

The thermooxidative and thermal stability of polypropylene nanocomposite with fully exfoliated MMT was studied by simultaneous measurements by DSC and TGA methods in a wide range of temperature. By comparing both the mass loss from TGA and enthalpy changes from DSC in a temperature range from room temperature to 500°C it was possible to identify precisely the specific mechanisms of

Jan Golebiewski; Andrzej Galeski

2007-01-01

245

Application of DSC as a tool for honey floral species characterization and adulteration detection  

Microsoft Academic Search

The thermal behaviour of authentic honeys and sugar syrups (industrial and homemade) was investigated by DSC. To confirm the first previous results concerning the effect of adulteration on the thermal behaviour of authentic honeys, 30 honey samples (Robinia, Lavender, Chestnut and Fir) were analyzed by DSC and their T\\u000ag were measured following a suited experimental protocol. The results indicated

C. Cordella; J.-P. Faucon; D. Cabrol-Bass; N. Sbirrazzuoli

2003-01-01

246

Insights into protein-polysorbate interactions analysed by means of isothermal titration and differential scanning calorimetry.  

PubMed

Therapeutic proteins formulated as liquid solutions at high protein concentration are very sensitive to chemical and physical degradation. Especially avoiding the formation of protein aggregates is very crucial for product quality. In order to stabilize the colloidal properties of protein therapeutics various excipient are used. Especially the detergents polysorbate 20 and 80 are common. However, the mechanism upon which the detergents protect the protein from aggregation is not really known. The present study investigates the interaction of polysorbate 20 and 80 with different proteins: lysozyme, bovine serum albumin (BSA) and an immunoglobulin. The interaction and binding of the detergents to the proteins is investigated by isothermal titration calorimetry (ITC). From ITC the thermodynamic parameters (DeltaH: change in enthalpy, DeltaS: entropy and DeltaG: free energy) upon binding are derived as well as the binding constant K (a). The thermal stability of the proteins in the presence of the detergent is assessed by differential scanning calorimetry (DSC). The results show that both detergents bind to BSA with K (a) between 8 and 12 x 10(3) M(-1) with DeltaH -50 to -60 kJ/mol (25 degrees C). One to two detergent molecules bind to BSA. The presence of both detergents induces a weak stabilisation of the thermal denaturation properties of BSA. However, the interaction of polysorbate 20 and 80 with lysozyme and the immunoglobulin is quite negligible. The presence of the detergents up to a concentration of 2 mM has no impact on the heat capacity curve neither a destabilisation nor a stabilisation of the native conformation is observed. PMID:19189101

Hoffmann, Claudia; Blume, Alfred; Miller, Inge; Garidel, Patrick

2009-06-01

247

Implementation of DSC model and application for analysis of field pile tests under cyclic loading  

NASA Astrophysics Data System (ADS)

The disturbed state concept (DSC) model, and a new and simplified procedure for unloading and reloading behavior are implemented in a nonlinear finite element procedure for dynamic analysis for coupled response of saturated porous materials. The DSC model is used to characterize the cyclic behavior of saturated clays and clay-steel interfaces. In the DSC, the relative intact (RI) behavior is characterized by using the hierarchical single surface (HISS) plasticity model; and the fully adjusted (FA) behavior is modeled by using the critical state concept. The DSC model is validated with respect to laboratory triaxial tests for clay and shear tests for clay-steel interfaces. The computer procedure is used to predict field behavior of an instrumented pile subjected to cyclic loading. The predictions provide very good correlation with the field data. They also yield improved results compared to those from a HISS model with anisotropic hardening, partly because the DSC model allows for degradation or softening and interface response.

Shao, Changming; Desai, Chandra S.

2000-05-01

248

Enzyme activity determination on macromolecular substrates by isothermal titration calorimetry: application to mesophilic and psychrophilic chitinases  

Microsoft Academic Search

Isothermal titration calorimetry has been applied to the determination of the kinetic parameters of chitinases (EC 3.2.1.14) by monitoring the heat released during the hydrolysis of chitin glycosidic bonds. Experiments were carried out using two different macromolecular substrates: a soluble polymer of N-acetylglucosamine and the insoluble chitin from crab shells. Different experimental temperatures were used in order to compare the

Thierry Lonhienne; Etienne Baise; Georges Feller; Vassilis Bouriotis; Charles Gerday

2001-01-01

249

Thermodynamics of Cationic Lipid-DNA Complex Formation as Studied by Isothermal Titration Calorimetry  

Microsoft Academic Search

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 1kcal absorbed per mole of lipid or DNA charge. This enthalpy change was attributed to DNA-DNA mutual

Edwin Pozharski; Robert C. MacDonald

2002-01-01

250

Total Absorption Dual Readout Calorimetry R&D  

NASA Astrophysics Data System (ADS)

This calorimetry R&D focuses on establishing a proof of concept for totally active hadron calorimetry. The research program involves evaluating the performance of the different crystal and glass samples in combination with different light collection and readout alternatives to optimize simultaneous collection of ?erenkov and scintillation light components for application of the Dual Readout technique to total absorption calorimetry. We performed initial studies in two short test beam phases in April and November 2010 at Fermilab. Here we present first measurements from these two beam tests.

Bilki, B.; Onel, Y.; Para, A.; Pauletta, G.; Rubinov, P.; Vasilas, I.; Wenzel, H.

251

Thermal and Structural Behavior of Dioctadecyldimethylammonium Bromide Dispersions Studied by Differential Scanning Calorimetry and X-Ray Scattering  

PubMed Central

Dioctadecyldimethylammonium bromide (DODAB) is a double chain cationic lipid, which assembles as bilayer structures in aqueous solution. The precise structures formed depend on, e.g., lipid concentration and temperature. We here combine differential scanning calorimetry (DSC) and X-ray scattering (SAXS and WAXS) to investigate the thermal and structural behavior of up to 120 mM DODAB in water within the temperature range 1–70°C. Below 1 mM, this system is dominated by unilamellar vesicles (ULVs). Between 1 and 65 mM, ULVs and multilamellar structures (MLSs) co-exist, while above 65 mM, the MLSs are the preferred structure. Depending on temperature, DSC and X-ray data show that the vesicles can be either in the subgel (SG), gel, or liquid crystalline (LC) state, while the MLSs (with lattice distance d ?=?36.7 Å) consist of interdigitated lamellae in the SG state, and ULVs in the LC state (no Bragg peak). Critical temperatures related to the thermal transitions of these bilayer structures obtained in the heating and cooling modes are reported, together with the corresponding transition enthalpies.

Feitosa, Eloi; Adati, Renata D.; Hansson, Per; Malmsten, Martin

2012-01-01

252

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

PubMed Central

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

Tabbakhian, M.; Rogers, J.A.

2012-01-01

253

Differential scanning calorimetry studies on sunscreen loaded solid lipid nanoparticles prepared by the phase inversion temperature method.  

PubMed

Solid lipid nanoparticles (SLN) are regarded as interesting carriers to improve sunscreens' safety and effectiveness. In this work, surfactant effects on the physico-chemical properties of SLN loading two of the most widely used UV-filters, octylmethoxycinnamate (OMC) and butylmethoxydibenzoylmethane (BMBM), were evaluated and the interactions between SLN components and loaded UV-filters were investigated by differential scanning calorimetry (DSC). All the SLN showed a mean size ranging from 30 to 95 nm, and a single peak in size distribution. The use of isoceth-20 or oleth-20 as primary surfactants did not provide SLN with suitable physico-chemical properties since: (a) OMC loaded SLN proved unstable; (b) BMBM could not be loaded. OMC or BMBM loaded SLN prepared using ceteth-20 as primary surfactant were stable but their loading capacity lowered when both sunscreens were loaded simultaneously. DSC analyses showed that OMC distributed inside the SLN and caused a decrease of the lipid matrix molecules cooperativity while BMBM did not affect SLN calorimetric behaviour. When OMC and BMBM were loaded together into these SLN, an interaction between BMBM and OMC occurred. These results suggest that the interactions between sunscreens and between sunscreens and SLN components deserve further investigation to evaluate their effect on UV-filter-loaded SLN effectiveness. PMID:21679757

Montenegro, L; Sarpietro, M G; Ottimo, S; Puglisi, G; Castelli, F

2011-08-30

254

Progress and new directions in high temperature calorimetry  

Microsoft Academic Search

Calorimetry at 600–900° C, using Calvet-type microcalorimeters, has provided data in several areas of interest to geology. The best-developed application is solution calorimetry in molten oxide solvents (lead borate, sodium molybdate) to determine the enthalpies of formation of anhydrous silicates and related minerals, the enthalpies of phase transformations and order-disorder reactions, and the enthalpies of mixing in molten salts, glasses,

Alexandra Navrotsky

1977-01-01

255

PREFACE: XIV International Conference on Calorimetry in High Energy Physics  

NASA Astrophysics Data System (ADS)

The International Conferences on Calorimetry in High Energy Physics (also known as the Calor Conference series, started in October 1990 at Fermilab) address all aspects of calorimetric particle detection and measurement, with an emphasis on high energy physics experiments. The XIV International Conference on Calorimetry in High Energy Physics (Calor 2010) was held at the campus of the Institute of High Energy Physics, Beijing, China, from May 10-14, 2010. This conference brought together more than 110 participants from 20 countries, including senior scientists and young physicists. During the five days of the conference, 98 presentations were given in seven plenary sessions. The attendees had in-depth discussions on the latest developments and innovations in calorimetry, including the exciting new LHC results. From the presentations, 83 papers were published in this proceedings. The success of the conference was due to the participants' enthusiasm and the excellent talks given by the speakers, and to the conveners for organizing the individual sessions. We would like to thank the International Advisory Committee for giving us the opportunity to host this Conference in Beijing. Finally we would like to thank all the people involved in the organization of the Conference, who have provided valuable local support. Yifang WangChair of Local Organizing Committee International Advisory Committee M DanilovITEP Moscow M DiemozINFN Roma I A EreditatoBern F L FabbriINFN Frascati T KobayashiICEPP Tokyo M LivanPavia University & INFN P LubranoINFN Perugia S MagillANL Argonne A MaioLIPP Lisbon H OberlackMPI Munich A ParaFermilab R WigmansTTU Lubbock R YoshidaANL Argonne R ZhuCaltech Local Organizing Committee Y WangIHEP (Chair) Y GaoTshinghua University T HuIHEP (Scientific secretary) C LiUSTC W LiIHEP J LuIHEP P WangIHEP T XuIHEP L ZhouIHEP Session Conveners 1) Materials and detectors - Junguang Lu (IHEP), Francesca Nessi (CERN) 2) Algorithm and simulation - Nural Akchurin (Texas Tech University), Weidong Li (IHEP) 3) Readout techniques - Gerald Eigen (University of Bergen), Zheng Wang (IHEP) 4) Operating calorimeters and calibration - Marat Gataullin (CERN), Francesco Lanni (BNL) 5) Future calorimetry - Tohru Takeshita (Shinshu University), Lei Xia (Argonne National Laboratory) 6) Astrophysics and neutrino calorimetry - Giuliana Fiorillo (INFN), Hiro Tajima (SLAC) List of Participants AKCHURIN, NuralTexas Tech University AN, ZhenghuaIHEP AUFFRAY, EtiennetteCERN BANFI, DaniloUniversità degli Studi di Milano, INFN BASHARINA-FRESHVILLE, AnastasiaUniversity College London BEAUCHEMIN, Pierre-HuguesUniversity of Oxford BENAGLIA, Andrea DavideUniversity of Milano - Bicocca and INFN BIAN, JianminIHEP BIINO, CristinaINFN BILKI, BurakUniversity of Iowa BLAHA, JanLAPP BOUDRY, VincentLLR / CNRS-IN2P3 CAI, XiaoIHEP CAPONE, AntonioPhysics Department University "La Sapienza" and INFN CAVALLARI, FrancescaCERN and INFN Rome CECCHI, ClaudiaUniversity di Perugia e INFN CHANG, JinfanIHEP CHEN, HuchengBrookhaven National Laboratory CHILDERS, TaylorUniversität Heidelberg - Kirchhoff-Institut für Physik DAO, ValerioGeneva University - DPNC DE LA TAILLE, ChristopheIN2P3/OMEGA-LAL DIEMOZ, MarcellaINFN Roma DOTTI, AndreaCERN EIGEN, GeraldUniversity of Bergen EPIFANOV, DenisBudker Institute of Nuclear Physics FAIVRE, JulienLPSC Grenoble France FANG, JianIHEP FANG, ShuangshiIHEP FANTONI, AlessandraINFN - LNF FERRI, FedericoCEA/Saclay Irfu/SPP FERRONI, FernandoSapienza University & INFN Roma FISK, Henry EugeneFermilab GABALDON, CarolinaCERN GARUTTI, ErikaDESY GAUDIO, GabriellaIstituto Nazionale di Fisica Nucleare - Sezione di Pavia GILLBERG, DagCarleton University GIOVANNINI, PaolaMax-Planck-Institut für Physik GLAZOV, AlexanderDESY GRACHOV, OlegUniversity of Kansas HAPPACHER, FabioINFN HE, MiaoIHEP HORI, YasutoUniversity of Tokyo, CNS HU, TaoIHEP HULTH, Per-OlofStockholm University JUN, Soon YungCarnegie Mellon University JURK, StefanISEG Spezialelektronik gmbH KAVATSYUK, MyroslavKVI, University of Groningen KHRAMOV, EvgenyJoint Institute

Wang, Yifang

2011-03-01

256

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

SciTech Connect

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.

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

257

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

PubMed Central

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 I2DTE segments. Iodination of the tyrosine rings in I2DTE 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 I2DTE) and PEG are a useful model system and the findings presented here may be applicable to other PEG-containing random copolymers as well. In copolymers of PEG and DTE and I2DTE, the presence of PEG depressed the glass transition temperature (Tg) of the copolymer relative to the homopolymer, poly(DTE carbonate), and the DTE/ I2DTE 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 Tg 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.

Murthy, N.S.; Wang, W.; Kohn, J.

2010-01-01

258

Differential scanning calorimetric (DSC) measurements on the roe of rainbow trout ( Oncorhynchus mykiss): influence of maturation and technological treatment  

Microsoft Academic Search

The roe of rainbow trout was investigated with respect to the effects of maturation and technological steps on the differential scanning calorimetric (DSC) curves of yolk proteins. The DSC curves were markedly effected during the first phase of maturation, while on the whole almost no changes were visible in the later stage. DSC curves measured on yolk proteins of rainbow

Reinhard Schubring

2004-01-01

259

Study of selected thermal characteristics of polypropylene\\/polyethylene binary blends using DSC and TGA  

Microsoft Academic Search

The characteristics of polypropylene\\/polyethylene (PP\\/PE) binary blends at the microscopic level have been widely studied by different researchers over the years. This communication discusses the empirical results obtained from a series of DSC and TGA tests on the selected thermal properties of PP\\/PE blends. Using DSC in our investigation is aimed at revealing the effects of different blending ratios of

A. C.-Y. Wong; F. Lam

2002-01-01

260

Determination of the enthalpy of phase change materials by inverse method from calorimetric experiments. Applications to pure substances or binary solutions  

NASA Astrophysics Data System (ADS)

The aim of this paper is to present an inverse identification method to determine specific enthalpy of PCM from calorimetry experiments. We will focus on the cases of pure substances and ideal binary solutions including the eutectic equilibrium. The corresponding direct model, based on energy balance, is first presented. A classical enthalpy method is then used, which presents the advantage of easily decoupling the thermal transfers from the specific energetic behavior of the material (i.e. thermodynamical phenomenon). In the second part of the paper, we will present the used inverse method (genetic algorithms). The sensibilities of the different parameters for the identification are analyzed. Finally, we will present the identification from DSC experiments (1) at different rates of heating for pure substances and (2) at different concentrations of aqueous solutions of NHACl. In each case, we identify the thermodynamical parameters of the model and compare the corresponding thermograms with the experimental ones. A good agreement is obtained for both cases.

Gibout, Stéphane; Maréchal, William; Franquet, Erwin; Bédécarrats, Jean-Pierre; Haillot, Didier; Dumas, Jean-Pierre

2012-11-01

261

Interlayer thermal conductivity of rubrene measured by ac-calorimetry  

NASA Astrophysics Data System (ADS)

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.

Zhang, H.; Brill, J. W.

2013-07-01

262

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

PubMed

This paper presents a computer tool called DSC (Simulation based Controllers Design) that enables an easy design of control systems and strategies applied to wastewater treatment plants. Although the control systems are developed and evaluated by simulation, this tool aims to facilitate the direct implementation of the designed control system to the PC of the full-scale WWTP (wastewater treatment plants). The designed control system can be programmed in a dedicated control application and can be connected to either the simulation software or the SCADA of the plant. To this end, the developed DSC incorporates an OPC server (OLE for process control) which facilitates an open-standard communication protocol for different industrial process applications. The potential capabilities of the DSC tool are illustrated through the example of a full-scale application. An aeration control system applied to a nutrient removing WWTP was designed, tuned and evaluated with the DSC tool before its implementation in the full scale plant. The control parameters obtained by simulation were suitable for the full scale plant with only few modifications to improve the control performance. With the DSC tool, the control systems performance can be easily evaluated by simulation. Once developed and tuned by simulation, the control systems can be directly applied to the full-scale WWTP. PMID:21330730

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

2011-01-01

263

Yeast SREBP cleavage activation requires the Golgi Dsc E3 ligase complex  

PubMed Central

SUMMARY Mammalian lipid homeostasis requires proteolytic activation of membrane-bound sterol regulatory element binding protein (SREBP) transcription factors through sequential action of the Golgi Site-1 and Site-2 proteases. Here, we report that while SREBP function is conserved in fungi, fission yeast employs a different mechanism for SREBP cleavage. Using genetics and biochemistry, we identified four genes defective for SREBP cleavage, dsc1–4, encoding components of a transmembrane Golgi E3 ligase complex with structural homology to the Hrd1 E3 ligase complex involved in endoplasmic reticulum-associated degradation. The Dsc complex binds SREBP and cleavage requires components of the ubiquitin-proteasome pathway: the E2 conjugating enzyme Ubc4, the Dsc1 RING E3 ligase and the proteasome. dsc mutants display conserved aggravating genetic interactions with components of the multivesicular body pathway in fission yeast and budding yeast, which lacks SREBP. Together, these data suggest that the Golgi Dsc E3 ligase complex functions in a post-ER pathway for protein degradation.

Stewart, Emerson V.; Nwosu, Christine C.; Tong, Zongtian; Roguev, Assen; Cummins, Timothy D.; Kim, Dong-Uk; Hayles, Jacqueline; Park, Han-Oh; Hoe, Kwang-Lae; Powell, David W.; Krogan, Nevan J.; Espenshade, Peter J.

2011-01-01

264

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

NASA Astrophysics Data System (ADS)

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

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

1996-11-01

265

Preparation of Solid Derivatives by Differential Scanning Calorimetry.  

ERIC Educational Resources Information Center

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…

Crandall, E. W.; Pennington, Maxine

1980-01-01

266

BOUND WATER IN STRATUM CORNEUM MEASURED BY DIFFERENTIAL SCANNING CALORIMETRY  

Microsoft Academic Search

Differential scanning calorimetry has been used to study water binding in stratum corneum. Samples of various total water contents are frozen and melted and the latent heat of melting measured with a Perkin Elmer differential scanning calorimeter. From this the relative amounts of freezing (unbound) water and non-freezing (bound) water are calculated. The results show that the amount of bound

K. Walkley

1972-01-01

267

Direct measurement of protein binding energetics by isothermal titration calorimetry  

Microsoft Academic Search

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

Stephanie Leavitt; Ernesto Freire

2001-01-01

268

Present state and trends in the development of combustion calorimetry  

Microsoft Academic Search

Modern bomb and gas calorimeters produced in Russia and abroad are reviewed. The main trends and ways of improving bomb calorimeters\\u000a are described in retrospective form. Problems and aims in the area of gas calorimetry are considered.

E. N. Korchagina

1998-01-01

269

Some applications of indirect calorimetry to sports medicine.  

PubMed

Some applications of indirect calorimetry to sports medicine are discussed and exemplified by case reports. In particular, it is suggested that oxigen consumption can be employed to assess the effects of physical activity on fat-free tissues and that the respiratory quotient may offer some insights into the food habits of athletes. PMID:11487172

Severi, S; Malavolti, M; Battistini, N; Bedogni, G

2001-01-01

270

Superconducting phase in UGe2 by AC calorimetry  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

271

Fast sampling calorimetry with solid argon ionization chambers  

SciTech Connect

A proposal for the fast sampling calorimetry with solid argon as active medium and the preliminary results from the solid argon test cell are presented. The proposed test calorimeter module structure, the signal routing and the mechanical and cryogenic arrangements are also discussed.

Clark, E.; Linn, S.; Piekarz, H.; Wahl, H.; Womersley, J. [Florida State Univ., Tallahassee, FL (United States); Hansen, S.; Hurh, P.; Rivetta, C.; Sanders, R.; Schmitt, R.; Stanek, R.; Stefanik, A. [Fermi National Accelerator Lab., Batavia, IL (United States)

1992-12-31

272

Radiation effects on front-end electronics for noble liquid calorimetry  

SciTech Connect

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.

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

1994-12-01

273

Non-contact calorimetry of liquid metallic alloys under reduced gravity conditions  

NASA Astrophysics Data System (ADS)

Methods of non-contact calorimetry and their application to the measurement of the thermophysical properties of Zr-based liquid metallic alloys are described. These methods were developed for containerless processing in an electromagnetic levitation device under reduced gravity conditions. The experiments were performed in the course of the IML-2 and MSL-1 spacelab missions. Thermophysical properties measured include the specific heat, the enthalpy of fusion, the total hemispherical emissivity, and the effective thermal conductivity. Future applications will be focused on the measurement of thermophysical properties of liquid metallic alloys relevant to industrial processing. .

Wunderlich, R. K.; Fecht, H.-J.

2001-02-01

274

RheoDSC: A hyphenated technique for the simultaneous measurement of calorimetric and rheological evolutions  

NASA Astrophysics Data System (ADS)

A newly developed hyphenated technique is presented combining an existing rheometer and differential scanning calorimeter into a single experimental setup. Through the development of a fixation accessory for differential scanning calorimeter (DSC) crucibles and a novel rotor, the simultaneous measurement is performed inside the well-controlled thermal environment of a Tzero™ DSC cell. Hence, the evolution of thermal and flow properties of a material can be simultaneously measured using steady or oscillatory shear measurements and regular or modulated temperature DSC measurements. Along with the construction of a prototype, a validation of the design was performed. The technique offers interesting opportunities for the investigation of flow-induced transitions, for instance, crystallization or phase separation, and provides an asset for high-throughput screening of materials. The potential of the novel technique is demonstrated by two case studies: the chemorheology during the cure of a thermosetting epoxy-amine system and the flow-induced crystallization of syndiotactic polypropylene.

Kiewiet, S.; Janssens, V.; Miltner, H. E.; van Assche, G.; van Puyvelde, P.; van Mele, B.

2008-02-01

275

RheoDSC: a hyphenated technique for the simultaneous measurement of calorimetric and rheological evolutions.  

PubMed

A newly developed hyphenated technique is presented combining an existing rheometer and differential scanning calorimeter into a single experimental setup. Through the development of a fixation accessory for differential scanning calorimeter (DSC) crucibles and a novel rotor, the simultaneous measurement is performed inside the well-controlled thermal environment of a Tzero DSC cell. Hence, the evolution of thermal and flow properties of a material can be simultaneously measured using steady or oscillatory shear measurements and regular or modulated temperature DSC measurements. Along with the construction of a prototype, a validation of the design was performed. The technique offers interesting opportunities for the investigation of flow-induced transitions, for instance, crystallization or phase separation, and provides an asset for high-throughput screening of materials. The potential of the novel technique is demonstrated by two case studies: the chemorheology during the cure of a thermosetting epoxy-amine system and the flow-induced crystallization of syndiotactic polypropylene. PMID:18315314

Kiewiet, S; Janssens, V; Miltner, H E; Van Assche, G; Van Puyvelde, P; Van Mele, B

2008-02-01

276

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

PubMed Central

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

2013-01-01

277

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

PubMed

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

Tananuwong, Kanitha; Reid, David S

2004-06-30

278

Dissolution, solubility, XRD, and DSC studies on flurbiprofen-nicotinamide solid dispersions.  

PubMed

Flurbiprofen-nicotinamide solid dispersions were prepared by the fusion method. The solid dispersions were evaluated for dissolution rate. The drug-carrier interaction in the liquid and solid states were studied by using phase solubility analysis, phase diagram, X-ray diffraction (XRD), and differential scanning calorimentry (DSC). Solid dispersions gave fast and rapid dissolution of flurbiprofen compared with the pure drug and the physical mixture. Phase diagram and DSC indicated that flurbiprofen and nicotinamide form a eutectic mixture. The aqueous solubility of flurbiprofen was enhanced in the presence of nicotinamide. PMID:16093207

Varma, M M; Pandi, J K

2005-05-01

279

In situ kinetics study of the accelerated aging of poly(ethylene oxide) using PhotoDSC.  

PubMed

PhotoDSC has been applied to follow the global kinetics of chain scissions resulting from the UV light irradiation or from the thermal degradation of a high molecular weight PEO (4 x 10(6) g x mol(-1)). Infrared spectroscopy, XRD measurements and rheology experiments were performed to evidence the occurrence of chain scissions. Melting energy was used as a tool to quantify the extent of the degradation. It was found that the chain scissions reaction follows a first-order kinetic law for both photo and thermal degradation. The activation energies were found identical in both cases (41 kJ x mol(-1)), whereas the degradation rate was higher in the case of UV irradiation than in the case of thermoageing. PMID:16869572

Fraisse, F; Morlat-Thérias, S; Gardette, J-L; Nedelec, J-M; Baba, M

2006-08-01

280

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

281

Differential scanning calorimetry and /sup 2/H NMR studies of the phase behavior of gramicidin-phosphatidylcholine mixtures  

SciTech Connect

The extents of two-phase coexistence in the phase diagrams of mixtures of gramicidin with 1,2-bis(perdeuteriopalmitoyl)-sn-glycero-3-phosphocholine (DPPC-d62) and with 1,2-bis(perdeuteriomyristoyl)-sn-glycero-3-phosphocholine (DMPC-d54) mixtures have been explored with differential scanning calorimetry (DSC) and deuterium nuclear magnetic resonance (/sup 2/H NMR). For both systems, increased gramicidin content causes a decrease in transition enthalpy and a broadening of the peak in excess heat capacity at the transition. In DMPC-d54-based mixtures, the broadening is roughly symmetric about the pure lipid transition temperature. Addition of gramicidin to DPPC-d62 extends the excess heat capacity peak on the low-temperature side, resulting in a slightly asymmetric scan. Deuterium NMR spectra showing a superposition of gel and liquid-crystalline components, observed for both mixtures, indicate the presence of two-phase coexistence. For the DPPC-d62-based mixtures, two-phase coexistence is restricted to an approximately 2 degrees C temperature range below the pure transition temperature. For DMPC-d54-based mixtures, the region of two-phase coexistence is even narrower. For both mixtures, beyond a gramicidin mole fraction of 2%, distinct gel and liquid-crystal contributions to the spectra cannot be distinguished. Along with the broad featureless nature of the DSC scan in this region, this is taken to indicate that the transition has been replaced by a continuous phase change. These results are consistent with the existence of a closed two-phase region having a critical concentration of gramicidin below 2 mol%.

Morrow, M.R.; Davis, J.H.

1988-03-22

282

Differential scanning calorimetry studies on the cysts of the potato-cyst nematode Globodera rostochiensis during freezing and melting  

PubMed

Differential scanning calorimetry (DSC) was used to determine the thermal events associated with freezing and melting of the cysts of the potato-cyst nematode Globodera rostochiensis. There were no thermal events during the cooling of dry cysts from 5 to -60 °C and warming back to 5 °C, indicating the absence of water freezing in the dry cysts. During heating of dry cysts from 5 to 80 °C, two overlapping endothermic events were observed at 55 °C, indicating the irreversible destruction of the permeability barrier of the eggshell by the melting of the lipids which constitute the lipid layer. The first exothermic event (T=-9 °C) during the cooling of hydrated cysts indicates the presence of an ice-nucleating agent. A broad exotherm at -38 °C is due to the freezing of eggs. DSC thus confirms that the eggshell prevents exogenous ice nucleation and allows the eggs to supercool in the presence of external ice. The enthalpy of the egg exotherm increased during hydration of the cysts. The temperature of the egg exotherm was elevated after heating of the sample to 70 °C. This is thought to be due to the loss of trehalose from the eggs following the destruction of the permeability barrier of the eggshell. During melting, three endothermic events were observed. These became merged after the destruction of the permeability barrier of the eggshell by heating, and only two peaks were observed in isolated eggs. The sample is thus considered to consist of three freezable compartments: (1) the water surrounding the cyst, (2) the solution between the cyst wall and the eggs and (3) the egg contents. PMID:9320478

Wharton; RamlØV

1995-01-01

283

Differential Scanning Calorimetry and Evolved Gas Analysis of Hydromagnesite  

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

284

Differential scanning calorimetry and electron diffraction investigation on low-temperature aging in Al-Zn-Mg alloys  

SciTech Connect

Differential scanning calorimetry (DSC) has been combined with transmission electron microscopy (TEM) to investigate the low-temperature decomposition processes taking place in an Al-5 wt pct Zn-1 wt pct Mg alloy. It was confirmed that two types of GP zones, i.e., GP(I) (solute-rich clusters) and GP(II) (vacancy-rich clusters), formed independently during decomposition of the supersaturated solid solution. The GP(I) zones form at a relatively low aging temperature and dissolve when the aging temperature is increased. The GP(II) zones are stable over a wider range of temperatures. To investigate the nature of the zones in the Al-Zn-Mg alloy, differential scanning calorimetry and transmission electron microscopy have also been carried out on binary Al-Zn alloys containing 5 wt pct and 10 wt pct Zn. In these Al-Zn alloys, GP zones formed rapidly during quenching, and they gave rise to characteristic electron diffraction patterns identical to those from GP(II) in the Al-Zn-Mg alloy system, implying that GP(II) zones in Al-Zn-Mg alloys are very similar to the zones formed in binary Al-Zn alloys. Thus, it is likely that GP(II) zones in Al-Zn-Mg alloys are zinc-rich clusters. In the Al-5 wt pct Zn-1 wt pct Mg alloy, both GP(I) and GP(II) were found to transform to {eta}{prime} and/or {eta} particles during heating in the differential scanning calorimeter. The {eta}{prime} was also observed to form after prolonged isothermal aging of the Al-Zn-Mg alloy at 75 C or after short aging times at 125 C.

Jiang, X.J.; Noble, B.; Holme, B.; Waterloo, G.; Tafto, J.

2000-02-01

285

Blends of polycaprolactone with polyvinylalcohol: a DSC, optical microscopy and solid state NMR study  

Microsoft Academic Search

Blend films of polycaprolactone (PCL) and polyvinylalcohol (PVAl) have been obtained by evaporation of a solution of both components in hexafluoroisopropanol. The miscibility of the polymers in the amorphous part of the blend has been studied by conventional methods (optical microscopy, DSC and FTIR) and by solid state NMR. Phase separation is observed in the melt. The absence of any

C. De Kesel; C. Lefèvre; J. B. Nagy; C. David

1999-01-01

286

Crystallization kinetics of a lithium zinc silicate glass studied by DTA and DSC  

Microsoft Academic Search

The crystallization kinetics of a lithium zinc silicate glass have been determined using isothermal and non-isothermal DSC and non-isothermal DTA. Values for the kinetic parameters for as-quenched and nucleated samples are reported and discussed. Particular reference is given to the similarities and differences noted between isothermally and non-isothermally derived data.

I. W. Donald

2004-01-01

287

The crystallization kinetics of a glass based on the cordierite composition studied by DTA and DSC  

Microsoft Academic Search

The crystallization kinetics of a glass based on the cordierite composition have been studied by DTA and DSC. Crystallization has been observed to be very dependent on the particle size of the glass employed, indicating a strong dependence on surface crystallization. For coarse particle sizes (eg. 600–1000 ?m) a single crystallization exotherm is obtained, corresponding to the formation of ?-cordierite.

I. W. Donald

1995-01-01

288

NMR, DSC and High Pressure Electrical Conductivity Studies on Liquid and Hybrid Electrolytes.  

National Technical Information Service (NTIS)

Electrical conductivity, DSC and Li-7 NMR studies have been carried out on liquid electrolytes such as EC:PC and EC:DMC containing LiPF6 (and LiCF3SO3 for NMR) and films plasticized using the same liquid electrolytes. The films are based on poly(vinyliden...

P. E. Stallworth J. J. Fontanella M. Wintersgill C. D. Scheidler J. J. Immel

1998-01-01

289

Accelerating rate calorimetry studies of the reactions between ionic liquids and charged lithium ion battery electrode materials  

Microsoft Academic Search

Using accelerating rate calorimetry (ARC), the reactivity between six ionic liquids (with and without added LiPF6) and charged electrode materials is compared to the reactivity of standard carbonate-based solvents and electrolytes with the same electrode materials. The charged electrode materials used were Li1Si, Li7Ti4O12 and Li0.45CoO2. The experiments showed that not all ionic liquids are safer than conventional electrolytes\\/solvents. Of

Yadong Wang; K. Zaghib; A. Guerfi; Fernanda F. C. Bazito; Roberto M. Torresi; J. R. Dahn

2007-01-01

290

Scintillating Glasses for Total Absorption Dual Readout Calorimetry  

NASA Astrophysics Data System (ADS)

Scintillating glasses are a potentially cheaper alternative to crystal - based calorimetry with common problems related to light collection, detection and processing. As such, their use and development are part of more extensive R&D aimed at investigating the potential of total absorption, combined with the readout (DR) technique, for hadron calorimetry. A recent series of measurements, using cosmic and particle beams from the Fermilab test beam facility and scintillating glass with the characteristics required for application of the DR technique, serve to illustrate the problems addressed and the progress achieved by this R&D. Alternative solutions for light collection (conventional and silicon photomultipliers) and signal processing are compared, the separate contributions of scintillation and Cherenkov processes to the signal are evaluated and results are compared to simulation.

Bonvicini, V.; Driutti, A.; Cauz, D.; Pauletta, G.; Rubinov, P.; Santi, L.; Wenzel, H.

2012-12-01

291

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)

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.

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

2007-11-01

292

Competitive crystallization of a propylene/ethylene random copolymer filled with a ?-nucleating agent and multi-walled carbon nanotubes. Conventional and ultrafast DSC study.  

PubMed

A propylene/ethylene polymeric matrix was reinforced by the simultaneous addition of a ?-nucleating agent (calcium pimelate) and multi-walled carbon nanotubes (MWCNTs) in various concentrations. The present manuscript explores the competitive crystallization tendency that is caused by the presence of the two fillers. On the one hand, calcium pimelate forces the material to crystallize predominantly in the ?-crystalline form, while, on the other, the strong ?-nucleating ability of MWCNTs compels the material to develop higher ?-crystalline content. An in-depth study has been performed on the nanocomposite samples by means of conventional, temperature-modulated, and differential fast scanning calorimetry (DFSC) under various dynamic and isothermal conditions. The results showed that ?-crystals are predominant at low MWCNT content (<2.5 wt %), while, at high MWCNT content, the material crystallizes mainly in the ?-form. The recrystallization phenomenon during melting was confirmed with step-scan DSC, and the use of very high cooling rates by UFDSC made it possible to achieve and study the nucleation of the samples. The presence of MWCNTs enabled the nanocomposites to crystallize faster under both isothermal and dynamic conditions. The activation energy of the samples was also calculated according to Friedman's theory. PMID:24224932

Papageorgiou, Dimitrios G; Papageorgiou, George Z; Zhuravlev, Evgeny; Bikiaris, Dimitrios; Schick, Christoph; Chrissafis, Konstantinos

2013-11-27

293

Differential scanning calorimetry of palm kernel oil products  

Microsoft Academic Search

A variety of fractionated and hydrogenated fats were derived from a commercial sample of Malayan palm kernel oil. These were\\u000a studied by differential scanning calorimetry at different rates of cooling and heating. The resulting thermograms, and latent\\u000a heats derived from them, were compared with one another and with underlying triglyceride compositions. This enabled three\\u000a potential interpretations of the thermograms to

J. B. Rossell

1975-01-01

294

Calorimetry of Portland cement with metakaolins, quartz and gypsum additions  

Microsoft Academic Search

In this work two aluminic pozzolans (metakaolins) and a non-pozzolan were added to two Portland cements with very different\\u000a mineral composition, to determine the effect on the rate of heat release and the mechanisms involved. The main analytical\\u000a techniques deployed were: conduction calorimetry, pozzolanicity and XRD.\\u000a \\u000a The results showed that the two metakaolins induced stimulation of the hydration reactions due

V. Rahhal; R. Talero

2008-01-01

295

Association of DSC3 mRNA Down-Regulation in Prostate Cancer with Promoter Hypermethylation and Poor Prognosis  

PubMed Central

Background Desmocollin 3 (DSC3), a member of the cadherin gene superfamily, is associated with pathogenesis of some cancers, but its role in prostate cancer (PCa) remains largely unknown. Methods DSC3 gene expression level in available PCa microarray dataset was examined using the Oncomine database. DSC3 transcript expression in prostate cell line panel and an independent tissue cohort (n?=?52) was estimated by quantitative PCR (Q-PCR). Epigenetic status of DSC3 gene promoter in PCa was investigated by uploading three dataset (ENCODE Infinium 450K array data and two methylation sequencing) in UCSC genome browser. While pyrosequencing analysis measured promoter DNA methylation, Q-PCR estimates were obtained for DSC3 transcript re-expression after 5-Aza-deoxycytidine (5-Aza) treatment. Clinical relevance of DSC3 expression was studied by Kaplan-Meier survival analysis. Finally, functional studies monitoring cell proliferation, migration and invasion were performed in prostate cell lines after siRNA mediated DSC3 knockdown or following 5-Aza induced re-expression. EMT markers Vimentin and E-cadherin expression was measured by Western Blot. Results Microarray data analyses revealed a significant decrease in DSC3 transcript expression in PCa, compared to benign samples. Q-PCR analysis of an independent cohort revealed DSC3 transcript down-regulation, both in PCa cell lines and tumor tissues but not in their benign counterpart. Examination of available NGS and Infinium data identified a role for epigenetic regulation DSC3 mRNA reduction in PCa. Pyrosequencing confirmed the increased DSC3 promoter methylation in cancer cell lines and restoration of transcript expression upon 5-Aza treatment further corroborated this epigenetic silencing mechanism. Importantly Kaplan-Meier analysis of an outcome cohort showed an association between loss of DSC3 expression and significantly increased risk of biochemical recurrence. Functional studies indicate a role for epithelial–mesenchymal transition in DSC3 regulated cell migration/invasion. Conclusion Taken together, our data suggests that DNA methylation contributes to down-regulation of DSC3 in prostate cancer, and loss of DSC3 predicts poor clinical outcome.

Mo, Chengqiang; Wang, Daohu; Chen, Junxing; Mao, Xiaopeng; Guo, Shengjie; Zhuang, Jintao; Qiu, Shaopeng

2014-01-01

296

The thermotropic phase behaviour and phase structure of a homologous series of racemic beta-D-galactosyl dialkylglycerols studied by differential scanning calorimetry and X-ray diffraction.  

PubMed

The thermotropic phase behaviour of aqueous dispersions of some synthetic 1,2-di-O-alkyl-3-O-(beta-D-galactosyl)-rac-glycerols (rac-beta-D-GalDAGs) with both odd and even hydrocarbon chain lengths was studied by differential scanning calorimetry (DSC), small-angle (SAXS) and wide-angle (WAXS) X-ray diffraction. DSC heating curves show a complex pattern of lamellar (L) and nonlamellar (NL) phase polymorphism dependent on the sample's thermal history. On cooling from 95 degrees C and immediate reheating, rac-beta-D-GalDAGs typically show a single, strongly energetic phase transition, corresponding to either a lamellar gel/liquid-crystalline (L(beta)/L(alpha)) phase transition (N< or =15 carbon atoms) or a lamellar gel/inverted hexagonal (L(beta)/H(II)) phase transition (N> or =16). At higher temperatures, some shorter chain compounds (N=10-13) exhibit additional endothermic phase transitions, identified as L/NL phase transitions using SAXS/WAXS. The NL morphology and the number of associated intermediate transitions vary with hydrocarbon chain length. Typically, at temperatures just above the L(alpha) phase boundary, a region of phase coexistence consisting of two inverted cubic (Q(II)) phases are observed. The space group of the cubic phase seen on initial heating has not been determined; however, on further heating, this Q(II) phase disappears, enabling the identification of the second Q(II) phase as Pn3 m (space group Q(224)). Only the Pn3 m phase is seen on cooling. Under suitable annealing conditions, rac-beta-D-GalDAGs rapidly form highly ordered lamellar-crystalline (L(c)) phases at temperatures above (N< or =15) or below (N=16-18) the L(beta)/L(alpha) phase transition temperature (T(m)). In the N< or =15 chain length lipids, DSC heating curves show two overlapping, highly energetic, endothermic peaks on heating above T(m); corresponding changes in the first-order spacings are observed by SAXS, accompanied by two different, complex patterns of reflections in the WAXS region. The WAXS data show that there is a difference in hydrocarbon chain packing, but no difference in bilayer dimensions or hydrocarbon chain tilt for these two L(c) phases (termed L(c1) and L(c2), respectively). Continued heating of suitably annealed, shorter chain rac-beta-D-GalDAGs from the L(c2) phase results in a phase transition to an L(alpha) phase and, on further heating, to the same Q(II) or H(II) phases observed on first heating. On reheating annealed samples with longer chain lengths, a subgel phase is formed. This is characterized by a single, poorly energetic endotherm visible below the T(m). SAXS/WAXS identifies this event as an L(c)/L(beta) phase transition. However, the WAXS reflections in the di-16:0 lipid do not entirely correspond to the reflections seen for either the L(c1) or L(c2) phases present in the shorter chain rac-beta-D-GalDAGs; rather these consist of a combination of L(c1), L(c2) and L(beta) reflections, consistent with DSC data where all three phase transitions occur within a span of 5 degrees C. At very long chain lengths (N> or =19), the L(beta)/L(c) conversion process is so slow that no L(c) phases are formed over the time scale of our experiments. The L(beta)/L(c) phase conversion process is significantly faster than that seen in the corresponding rac-beta-D-GlcDAGs, but is slower than in the 1,2-sn-beta-D-GalDAGs already studied. The L(alpha)/NL phase transition temperatures are also higher in the rac-beta-D-GalDAGs than in the corresponding rac-beta-D-GlcDAGs, suggesting that the orientation of the hydroxyl at position 4 and the chirality of the glycerol molecule in the lipid/water interface influence both the L(c) and NL phase properties of these lipids, probably by controlling the relative positions of hydrogen bond donors and acceptors in the polar region of the membrane. PMID:17524381

Mannock, David A; Collins, Marcus D; Kreichbaum, Manfried; Harper, Paul E; Gruner, Sol M; McElhaney, Ronald N

2007-07-01

297

Preformulation Studies of Zidovudine Derivatives: Acid Dissociation Constants, Differential Scanning Calorimetry, Thermogravimetry, X-Ray Powder Diffractometry and Aqueous Stability Studies  

PubMed Central

As part as of the preformulation studies of new 5?-OH derivatives of zidovudine, compounds 2–6, their acid dissociation constants, Differential Scanning Calorimetry (DSC) and Thermogravimetry (TG) curves, X-Ray Powder diffractograms and aqueous stability are reported. A sensitive technique such as differential scanning potentiometry was used to determine the pKa constants of the above mentioned compounds. In addition, pKa values were calculated from theoretical methods, and no significant differences with those of experimental ones were observed. X-Ray Powder Diffractometry data demonstrated that compounds 2–4 were crystalline while 5 and 6 were amorphous. DSC analysis indicated that all of them presented an exothermic decomposition peak above 150 °C which is accompanied by a weight loss in the respective TG curves. The stability of these compounds in aqueous medium at different pH values was investigated, using a validated High Performance Liquid Chromatography (HPLC) method, which demonstrated to be rapid, selective, sensitive, accurate and stability-indicating. Good recovery, linearity and precision were also achieved. For all compounds the aqueous hydrolysis followed a pseudo-first-order kinetics, depending on pH and the union existing between AZT and the associate moiety. The hydrolysis was catalyzed by hydroxide ion in the 7.4–13.2 pH range, while all compounds exhibited pH-independent stability from acidic to neutral media (pHs 1.0–7.4).

Raviolo, Monica A.; Brinon, Margarita C.

2011-01-01

298

Estimation of the nucleation rate by differential scanning calorimetry  

NASA Technical Reports Server (NTRS)

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

Kelton, Kenneth F.

1992-01-01

299

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

NASA Astrophysics Data System (ADS)

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.

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

2008-07-01

300

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

PubMed

Enzymatic hydrolysis of high-solid biomass (>10% w/w dry mass) has become increasingly important as a key step in the production of second-generation bioethanol. To this end, development of quantitative real-time assays is desirable both for empirical optimization and for detailed kinetic analysis. In the current work, we have investigated the application of isothermal calorimetry to study the kinetics of enzymatic hydrolysis of two substrates (pretreated corn stover and Avicel) at high-solid contents (up to 29% w/w). It was found that the calorimetric heat flow provided a true measure of the hydrolysis rate with a detection limit of about 500 pmol glucose s(-1). Hence, calorimetry is shown to be a highly sensitive real-time method, applicable for high solids, and independent on the complexity of the substrate. Dose-response experiments with a typical cellulase cocktail enabled a multidimensional analysis of the interrelationships of enzyme load and the rate, time, and extent of the reaction. The results suggest that the hydrolysis rate of pretreated corn stover is limited initially by available attack points on the substrate surface (<10% conversion) but becomes proportional to enzyme dosage (excess of attack points) at later stages (>10% conversion). This kinetic profile is interpreted as an increase in polymer end concentration (substrate for CBH) as the hydrolysis progresses, probably due to EG activity in the enzyme cocktail. Finally, irreversible enzyme inactivation did not appear to be the source of reduced hydrolysis rate over time. PMID:20803262

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

2011-03-01

301

Temperature-pressure phase diagram of a heterogeneous anionic model biomembrane system: results from a combined calorimetry, spectroscopy and microscopy study.  

PubMed

By using Fourier transform infrared (FT-IR) spectroscopy in combination with differential scanning calorimetry (DSC) coupled with pressure perturbation calorimetry (PPC), ultrasound velocimetry, Laurdan fluorescence spectroscopy, fluorescence microscopy and atomic force microscopy (AFM), the temperature and pressure dependent phase behavior of the five-component anionic model raft lipid mixture DOPC/DOPG/DPPC/DPPG/cholesterol (20:5:45:5:25 mol%) was investigated. A temperature range from 5 to 65 °C and a pressure range up to 16 kbar were covered to establish the temperature-pressure phase diagram of this heterogeneous model biomembrane system. Incorporation of 10-20 mol% PG still leads to liquid-ordered (l(o))-liquid-disordered (l(d)) phase coexistence regions over a wide range of temperatures and pressures. Compared to the corresponding neutral model raft mixture (DOPC/DPPC/Chol 25:50:25 mol%), the p,T-phase diagram is - as expected and in accordance with the Gibbs phase rule - more complex, the phase sequence as a function of temperature and pressure is largely similar, however. This anionic heterogeneous model membrane system will serve as a more realistic model biomembrane system to study protein interactions with anionic lipid bilayers displaying liquid-disordered/liquid-ordered domain coexistence over a wide range of the temperature-pressure plane, thus allowing also studies of biologically relevant systems encountered under extreme environmental conditions. PMID:21262194

Kapoor, Shobhna; Werkmüller, Alexander; Denter, Christian; Zhai, Yong; Markgraf, Jonas; Weise, Katrin; Opitz, Norbert; Winter, Roland

2011-04-01

302

Differential scanning calorimetry and its applications to mineralogy and the geosciences  

Microsoft Academic Search

The review explores the contribution so far of DSC to the earth sciences. Outlined are the principles of power-compensated, heat-flux instruments and the measurement of enthalpies and specific heat. Areas covered in some detail include dehydration studies of minerals, mineral mixtures and the application of DSC to substitution effects in carbonates, particularly dolomite-ankerites. Also discussed is the use of DSC

J. V. Dubrawskl

303

Differential scanning calorimetry and its applications to mineralogy and the geosciences  

Microsoft Academic Search

The review explores the contribution so far of DSC to the earth sciences. Outlined are the principles of power-compensated, heat-flux instruments and the measurement of enthalpies and specific heat. Areas covered in some detail include dehydration studies of minerals, mineral mixtures and the application of DSC to substitution effects in carbonates, particularly dolomite-ankerites. Also discussed is the use of DSC

J. V. Dubrawski

1991-01-01

304

NMR, conductivity and DSC study of Li + transport in ethylene glycol\\/citric acid polymer gel  

Microsoft Academic Search

In this present paper the influence of viscosity on the ionic dynamics of polymer gel electrolytes prepared by the Pechini polymeric precursor method is investigated by impedance spectroscopy, differential scanning calorimetric (DSC) and NMR techniques. Polymer gel electrolytes are formed by ethylene glycol (EG) and citric acid (CA) and lithium perchlorate. Room temperature conductivity of the order of 2.3×10?4S\\/cm was

C. E. Tambelli; J. P. Donoso; C. J. Magon; E. C. Pereira; A. V. Rosario

2007-01-01

305

Detection of Adulteration in Iranian Olive Oils Using Instrumental (GC, NMR, DSC) Methods  

Microsoft Academic Search

This paper describes an investigation into the usefulness of some instrumental methods (GC, NMR, and DSC) in the detection\\u000a of adulteration of olive oil with soybean, sunflower, and canola oils (that are relatively cheap oils mixed as adulterants\\u000a with olive oil). These seed oils were compared with genuine and commercial olive oils, two of which appeared to have been\\u000a adulterated.

Maryam Jafari; Mahdi Kadivar; Javad Keramat

2009-01-01

306

Amodulated dsc study on the in situ polymerization of cyclic butylene terephthalateoligomers  

Microsoft Academic Search

The polymerization of a cyclic butylene terephthalate\\u000a (CBT) oligomer was studied as a function of temperature (T=200\\u000a and 260C, respectively) by modulated DSC (MDSC). The first heating was\\u000a followed by cooling after various holding times (5, 15 and 30 min) prior to\\u000a the second heating which ended always at T=260C.\\u000a This allowed us to study the crystallization and melting behavior

Z. A. Mohd Ishak; P. P. Shang; J. Karger-Kocsis

2006-01-01

307

Calorimetry exchange program. Quarterly data report, 2nd quarter 1992  

SciTech Connect

The goals of the Calorimetry Sample Exchange Program are: (1) Discuss measurement differences, (2) Review and improve analytical measurements and methods, (3) Discuss new measurement capabilities, (4) Provide data to DOE on measurement capabilities to evaluate shipper-receiver differences, (5) Provide characterized or standard materials as necessary for exchange participants, (6) Provide a measurement control program for plutonium analysis. A sample of PuO{sub 2} powder is available at each participating site for NDA measurement, including either or both calorimetry and high-resolution gamma-ray spectroscopy, the elements which are typically combined to provide a calorimetric assay of plutonium. The facilities measure the sample as frequently and to the level of precision which they desire, and then submit the data to the Exchange for analysis. Statistical tests are used to evaluate the data and to determine if there are significant differences from accepted values for the exchange 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. 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.

Barnett, T.M.

1996-07-01

308

Calorimetry exchange program annual data report for 1992  

SciTech Connect

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. 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. This document provides data for 1992.

Barnett, T.M.

1992-12-31

309

Calorimetry exchange program. Quarterly data report, 1st quarter 1991  

SciTech Connect

The goals of the Calorimetry Sample Exchange Program are: (1) Discuss measurement differences, (2) Review and improve analytical measurements and methods, (3) Discuss new measurement capabilities, (4) Provide data to DOE on measurement capabilities to evaluate shipper-receiver differences, (5) Provide characterized or standard materials as necessary for exchange participants, (6) Provide a measurement control program for plutonium analysis. A sample of PuO{sub 2} powder is available at each participating site for NDA measurement, including either or both calorimetry and high-resolution gamma-ray spectroscopy, the elements which are typically combined to provide a calorimetric assay of plutonium. The facilities measure the sample as frequently and to the level of precision which they desire, and then submit the data to the Exchange for analysis. Statistical tests are used to evaluate the data and to determine if there are significant differences from accepted values for the exchange 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. 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.

McClelland, T.M.

1996-07-01

310

Calorimetry exchange program quarterly data report, fourth quarter CY92  

SciTech Connect

The goals of the Calorimetry Sample Exchange Program are: (1) discuss measurement differences (2) review and improve analytical measurements and methods (3) discuss new measurement capabilities (4) provide data to DOE on measurement capabilities to evaluate shipper- receiver differences (5) provide characterized or standard materials as necessary for exchange participants (6) provide a measurement control program for plutonium analysis A sample Of PUO2 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 reports as this document provides and as 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.

Barnett, T.M.

1992-12-31

311

Water Flow Calorimetry System of EAST Neutral Beam Injector  

NASA Astrophysics Data System (ADS)

Neutral beam injection (NBI) is recognized as one of the most effective means of plasma heating. The EAST NBI water flow calorimetry system (WFCS) based on PCI extensions for instrumentation (PXI) was established, it can measure temperature rise and flow rate of cooling water of the heat load components, and achieve beam power distribution and neutralization efficiency. Experimental data obtained from WFCS are feedback of the ion source operation state and direct the operation parameter optimization of the ion source. Experimental results show that the WFCS is stable, reliable, and meet the experimental requirements fully.

Yu, Ling; Hu, Chundong; Liu, Sheng; Xu, Yongjian

2013-10-01

312

Monitoring assembly of ribonucleoprotein complexes by isothermal titration calorimetry  

PubMed Central

Isothermal titration calorimetry (ITC) is a useful technique to study RNA-protein interactions, as it provides the only method by which the thermodynamic parameters of free energy, enthalpy, and entropy can be directly determined. This chapter presents a general procedure for studying RNA-protein interactions using ITC, and gives specific examples for monitoring the binding of Caenorhabditis elegans GLD-1 STAR domain to TGE RNA and the binding of Aquifex aeolicus S6:S18 ribosomal protein heterodimer to an S15-rRNA complex.

Recht, Michael I.; Ryder, Sean P.; Williamson, James R.

2010-01-01

313

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

PubMed Central

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.

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

2011-01-01

314

CSL/DSC lattice model for general crystal-crystal boundaries and their line defects  

SciTech Connect

The general CSL/DSC Lattice model for internal boundaries in crystalline materials is described. The model is essentially a fit-misfit model in which the regions of fit are patches where partial lattice matching across the boundary is achieved, and the regions of misfit are boundary line defects possessing dislocation/boundary step character. The degree of fit is effectively measured by the size of an appropriately chosen Coincidence Site Lattice (CSL) formed by the two lattices adjoining the boundary. The Burgers vectors of the line defects are vectors of an appropriately chosen DSC Lattice also formed by the two lattices adjoining the boundary, while the step vectors describing the step character are defined within the framework of the DSC Lattice. The model is extremely general and may be applied to grain boundaries in both cubic and non-cubic materials and interphase boundaries. Applications of the model to a variety of experimental results involving grain boundaries and interphase boundaries are discussed. Some general assessment of the current status of the model is attempted.

Balluffi, R.W.; Brokman, A.; King, A.H.

1981-12-01

315

CSL/DSC lattice model for general crystal boundaries and their line defects  

SciTech Connect

The general CSL/DSC Lattice model for internal boundaries in crystalline materials is described. The model is essentially a 'fit-misfit' model in which the regions of 'fit' are patches where partial lattice matching across the boundary is achieved and the regions of 'misfit' are boundary line defects possessing dislocation/boundary step character. The degree of 'fit' is effectively measured by the size of an appropriately chosen coincidence site lattice (CSL) formed by the two lattices adjoining the boundary. The Burgers vectors of the line defects are vectors of an appropriately chosen DSC Lattice also formed by the two lattices adjoining the boundary, while the step vectors describing the step character are defined within the framework of the DSC Lattice. The model is extremely general and may be applied to grain boundaries in both cubic and non-cubic materials and interphase boundaries. Applications of the model to a variety of experimental results involving grain boundaries and interphase boundaries are discussed. Some general assessment of the current status of the model is attempted.

Balluffi, R.W.; Brokman, A.; King, A.H.

1982-08-01

316

The DSC1 channel, encoded by the smi60E locus, contributes to odor-guided behavior in Drosophila melanogaster.  

PubMed

Previously, we generated P-element insert lines in Drosophila melanogaster with impaired olfactory behavior. One of these smell-impaired (smi) mutants, smi60E, contains a P[lArB] transposon in the second intron of the dsc1 gene near a nested gene encoding the L41 ribosomal protein. The dsc1 gene encodes an ion channel of unknown function homologous to the paralytic (para) sodium channel, which mediates neuronal excitability. Complementation tests between the smi60E mutant and several EP insert lines map the smell-impaired phenotype to the P[lArB] insertion site. Wild-type behavior is restored upon P-element excision. Evidence that reduction in DSC1 rather than in L41 expression is responsible for the smell-impaired phenotype comes from a phenotypic revertant in which imprecise P-element excision restores the DSC1 message while further reducing L41 expression. Behavioral assays show that a threefold decrease in DSC1 mRNA is accompanied by a threefold shift in the dose response for avoidance of the repellent odorant, benzaldehyde, toward higher odorant concentrations. In situ hybridization reveals widespread expression of the dsc1 gene in the major olfactory organs, the third antennal segment and the maxillary palps, and in the CNS. These results indicate that the DSC1 channel contributes to processing of olfactory information during the olfactory avoidance response. PMID:12196396

Kulkarni, Nalini H; Yamamoto, Akihiko H; Robinson, Kellie O; Mackay, Trudy F C; Anholt, Robert R H

2002-08-01

317

Calorimetry exchange program quarterly data report, third quarter 1992  

SciTech Connect

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.

Barnett, T.M.

1992-12-31

318

Calorimetry exchange program. Annual data report, Calendar Year 1993  

SciTech Connect

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.

Barnett, T.M.

1996-08-01

319

Impact of oxidized phospholipids on the structural and dynamic organization of phospholipid membranes: a combined DSC and solid state NMR study.  

PubMed

Membranes undergo severe changes under oxidative stress conditions due to the creation of oxidized phospholipid (OxPL) species, which possess molecular properties quite different from their parental lipid components. These OxPLs play crucial roles in various pathological disorders and their occurrence is involved in the onset of intrinsic apoptosis, a fundamental pathway in programmed mammalian cell death. However, the molecular mechanisms by which these lipids can exert their apoptotic action via their host membranes (e.g., altering membrane protein function) are poorly understood. Therefore, we studied the impact of OxPLs on the organization and biophysical properties of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) based lipid membranes by differential scanning calorimetry (DSC) and solid state nuclear magnetic resonance (NMR) spectroscopy. Incorporation of defined OxPLs with either a carboxyl group (1-palmitoyl-2-azelaoyl-sn-glycero-3-phosphocholine (PazePC)) or aldehyde (1-palmitoyl-(9'oxononanoyl)-sn-glycero-3-phosphocholine (PoxnoPC)) at their truncated sn-2-chain ends enabled us to reveal OxPL species-dependent differences. The calorimetric studies revealed significant effects of OxPLs on the thermotropic phase behavior of DMPC bilayers, especially at elevated levels where PazePC induced more pronounced effects than PoxnoPC. Temperature-dependent changes in the solid state 31P NMR spectra, which provided information of the lipid headgroup region in these mixed membrane systems, reflected this complex phase behavior. In the temperature region between 293 K (onset of the Lalpha-phase) and 298 K, two overlapping NMR spectra were visible which reflect the co-existence of two liquid-crystalline lamellar phases with presumably one reflecting OxPL-poor domains and the other OxPL-rich domains. Deconvolution of the DSC profiles also revealed these two partially overlapping thermal events. In addition, a third thermal, non-NMR-visible, event occurred at low temperatures, which can most likely be associated to a solid-phase mixing/demixing process of the OxPL-containing membranes. The observed phase transitions were moved to higher temperatures in the presence of heavy water due its condensing effect, where additional wideline 2H-NMR studies revealed a complex hydration pattern in the presence of OxPLs. PMID:23805755

Wallgren, Marcus; Beranova, Lenka; Pham, Quoc Dat; Linh, Khanh; Lidman, Martin; Procek, Jan; Cyprych, Konrad; Kinnunen, Paavo K J; Hof, Martin; Gröbner, Gerhard

2013-01-01

320

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

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

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

2012-01-01

321

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

SciTech Connect

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

Fernandez, Jose M., E-mail: joseman@sas.upenn.edu [Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, PA 19104-6316 (United States); Plaza, Cesar; Polo, Alfredo [Instituto de Ciencias Agrarias, Consejo Superior de Investigaciones Cientificas, Serrano 115 dpdo., 28006 Madrid (Spain); Plante, Alain F. [Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, PA 19104-6316 (United States)

2012-01-15

322

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

PubMed

Cell cultured skin equivalents present an alternative for dermatological in vitro evaluations of drugs and excipients as they provide the advantage of availability, lower variability and higher assay robustness compared to native skin. For penetration/permeation studies, an adequate stratum corneum barrier similar to that of human stratum corneum is, however, a prerequisite. In this study, the stratum corneum lipid organization in an epidermal cell culture model based on rat epidermal keratinocytes (REK organotypic culture, ROC) was investigated by small-angle X-ray scattering (SAXS) in dependence on ROC cultivation time and in comparison to native human and rat stratum cornea. In addition, the thermal phase behavior was studied by differential scanning calorimetry (DSC) and barrier properties were checked by measurements of the permeability of tritiated water. The development of the barrier of ROC SC obtained at different cultivation times (7, 14 and 21 days at the air-liquid interface) was connected with an increase in structural order of the SC lipids in SAXS measurements: Already cultivation for 14 days at the air-liquid interface resulted overall in a competent SC permeability barrier and SC lipid organization. Cultivation for 21 days resulted in further minor changes in the structural organization of ROC SC. The SAXS patterns of ROC SC had overall large similarities with that of human SC and point to the presence of a long periodicity phase with a repeat distance of about 122Å, e.g. slightly smaller than that determined for human SC in the present study (127Å). Moreover, SAXS results also indicate the presence of covalently bound ceramides, which are crucial for a proper SC barrier, although the corresponding thermal transitions were not clearly detectable by DSC. Due to the competent SC barrier properties and high structural and organizational similarity to that of native human SC, ROC presents a promising alternative for in vitro studies, particularly as it can be obtained under overall rather straightforward cell culture conditions and thus low assay costs. PMID:23770376

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

2013-12-18

323

Simulation and Analysis of Differential Scanning Calorimetry Output: Protein Unfolding Studies  

NASA Astrophysics Data System (ADS)

High sensitivity differential scanning calorimetry ( HSDSC ) is a powerful and increasingly used technique for the study of molecular energetics in relation to biopolymers (e.g. proteins and nucleic acids ) or biomacromolecular assemblies ( e.g. liposomes ). HSDSC is, for example, the only method which allows thermodynamic parameters to be obtained directly for protein unfolding. The thermodynamic basis for HSDSC signals obtained for the equilibrium unfolding of proteins as well as the formalism for generating simulations of HSDSC outputs for protein unfolding are discussed. This will allow students ( studying biophysical chemistry, biochemistry, biophysics, molecular biology and allied subjects at undergraduate and postgraduate level ) to obtain an understanding of the type of data analysis required for HSDSC experiments on proteins.

Chowdhry, Babur; Leharne, Stephen

1997-02-01

324

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

PubMed

DSC experiments were performed on aqueous solutions of PEO-PPO-PEO (P105) amphiphiles in the low concentration regime (0-1%) to resolve the critical micelle concentration (cmc) both neat and co-formulated with methylparaben (MP). Further work was done at 10% amphiphilic copolymer concentrations and co-formulated with MP to resolve the variations in enthalpy. The compensation temperature, T(compensation), was determined from the analyses for neat P105 as 293.9 K; adding MP raises this to 328.43 K. PMID:23474225

Thompson, Andre Lamont; Love, Brian James

2013-05-15

325

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

SciTech Connect

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

None

2010-02-17

326

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

ScienceCinema

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

327

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

ScienceCinema

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

None

2011-10-06

328

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

SciTech Connect

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''.

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

2001-12-31

329

True Triaxial and Directional Shear Cell Experiments on Dry Sand.  

National Technical Information Service (NTIS)

This report contains results from experiments on Leighton Buzzard sand performed in the multiaxial cubical apparatus (MCA)--or true triaxial apparatus--and the directional shear cell (DSC). These experiments provide a data bank for calibrating constitutiv...

S. Sture M. M. Alawi H. Y. Ko

1988-01-01

330

DSC of ? -irradiated ultra-high molecular weight polyethylene and high density polyethylene of normal molecular weight  

Microsoft Academic Search

The melting and the crystallization of?-irradiated (doses: 0–6Mrad) ultra-high molecular weight nascent polyethylene (UHMWPE) and high density nascent polyethylene with normal molecular weight (NMWPE) were investigated by DSC. The heat of melting of the nascent UHMWPE (DSC degree of crystallinity, respectively) increases up to a dose of 3 Mrad, after which it slightly decreases. The heat of the second melting

L. Minkova

1988-01-01

331

Hydroxylamine nitrate self-catalytic kinetics study with adiabatic calorimetry.  

PubMed

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

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

2009-03-15

332

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

SciTech Connect

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.

Andrew Stroud, Lee Sawyer

2012-08-31

333

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

NASA Astrophysics Data System (ADS)

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.

Chen, Dengyu; Li, Ming; Zhu, Xifeng

2012-12-01

334

A DSC study of Z 2 ?Z 3 viscosity blown soybean oil  

Microsoft Academic Search

The thermal oxidation of four commercially available neat blown soybean oil samples and a heat-bodied soybean oil sample,\\u000a obtained from various manufacturers, having Gardner bubble viscosities between Z2 and Z3 was investigated using nonisothermal DSC under a constant oxygen flow and a heating rate (?) ranging from 3 to 20C\\/min.\\u000a The extrapolated onset temperatures (T\\u000a \\u000a e1\\u000a and T\\u000a \\u000a e2\\u000a )

James A. Kenar; Joneen McElligott; Hong-Sik Hwang; Sevim Z. Erhan

2002-01-01

335

A DSC study of the miscibility of poly(ethylene oxide)-block-poly(DL-lactide) copolymers with poly(DL-lactide).  

PubMed

The purpose of this study was to examine the miscibility of poly(ethylene oxide)-block-poly(DL-lactide) copolymers with poly (DL-lactide). The copolymers L7E73L7 and L17E78L17 (L = carbonyloxymethylmethylene unit, OCOCH(CH3); E = oxyethylene unit, OCH2CH2) were synthesised by non-catalysed anionic polymerisation and characterised by gel permeation chromatography and 13C NMR. Blends of each of the copolymers with poly(DL-lactide) with compositions over the range from 10 to 90 wt% copolymer were cast as thin films and examined by differential scanning calorimetry (DSC) to determine glass transition temperatures (Tg) and melting temperatures (Tm). The phase diagram showed a region of miscibility above the melting point of the copolymer in the system (approx. 35-40 degrees C). Within this region the system was glassy at low mass fractions of oxyethylene in the copolymer (wE < or = 0.1) and rubbery at higher mass fractions. Below Tm a mechanically compatible glassy blend existed at low wE whilst quenching of systems of higher wE led to phase separation, the biphasic region consisting of crystalline Em-sequences of copolymer separated from non-crystalline poly(DL-lactide). The phase diagram resulting from this study provides the means for the design of drug delivery systems based on blends of poly(DL-lactide) and poly(ethylene oxide)-containing components. The crystal melt boundary can be lowered by the use of block copolymers with short poly(ethylene oxide) blocks permitting the preparation of blends which are miscible at room temperature and rubbery or glassy according to composition. PMID:10454009

Pannu, R K; Tanodekaew, S; Li, W; Collett, J H; Attwood, D; Booth, C

1999-08-01

336

Comparison of curdlan and its carboxymethylated derivative by means of Rheology, DSC, and AFM.  

PubMed

Curdlan was carboxymethylated in an aqueous alkaline medium using monochloroacetic acid as the etherifying agent. The structure of carboxymethylated curdlan (CMc) was analyzed by FT-IR and NMR spectroscopy, which revealed that the carboxymethyl group was introduced mainly at the C-6 position as well as at the C-2 and C-4 positions. Furthermore, CMc was compared with the native curdlan by using rheology and DSC methods. It was found that in water, both polysaccharides behaved as pseudoplastic fluids and fit the power law and Herschel-Bulkley rheological models well. Both the storage shear modulus G' and the loss shear modulus G'' of CMc aqueous solutions decreased and became more frequency dependent with decreasing concentration in comparison with the curdlan aqueous suspensions. The modulus-temperature curve also suggested that the gel characteristic of curdlan has been lost after chemical modification, which is consistent with the DSC results. AFM images revealed differences in the conformation of native and carboxymethylated curdlan, which changed from the aggregation of macromolecules to triple helices. All the experimental results suggest that the hydrogen bonds that bind curdlan with interstitial water to form the micelles have been destroyed completely and that the hydrophobic interactions related to the methylene groups at C-6 formed above 55 degrees C disappeared due to the introduction of the hydrophilic carboxymethyl group. PMID:16310757

Jin, Yang; Zhang, Hongbin; Yin, Yimei; Nishinari, Katsuyoshi

2006-01-16

337

Quartz Fibers: a New Calorimetry for Multi-TeV, Very Forward Physics  

NASA Astrophysics Data System (ADS)

A new calorimetry technique based on shower sampling of Cherenkov light in optical fibers is presented. Fast response, excellent radiation hardness, insensitivity to neutrons, shower core detection and this technolgie's static (no gas, no liquids) properties make it an excellent candidate for Very Forward Calorimetry (VFCal) for the LHC.

Anzivino, G.; Contin, A.; Dellacasa, G.; De Salvo, R.; Gorodetzky, P.; Johnson, K. F.; Juillot, P.; Lazic, D.; Lundin, M.; Marino, M.; Musso, A.

1995-11-01

338

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

PubMed

Differential scanning calorimetry (DSC) was used to determine the transition temperature ranges (TTR) of four types of super-elastic orthodontic nickel-titanium coil springs (Sentalloy). A knowledge of the TTR provides information on the temperature at which a NiTi wire or spring can assume superelastic properties and when this quality disappears. The spring types in this study can be distinguished from each other by their characteristic TTR during cooling and heating. For each tested spring type a characteristic TTR during heating (austenite transformation) and cooling (martensite transformation) was evaluated. The hysteresis of the transition temperature, found between cooling and heating, was 3.4-5.2 K. Depending on the spring type the austenite transformation started (As) at 9.7-17.1 degrees C and finished (Af) at 29.2-37 degrees C. The martensite transformation starting temperature (Ms) was evaluated at 32.6-25.4 degrees C, while Mf (martensite transformation finishing temperature) was 12.7-6.5 degrees C. The results show that the springs become super-elastic when the temperature increases and As is reached. They undergo a loss of super-elastic properties and a rapid decrease in force delivery when they are cooled to Mf. For the tested springs, Mf and As were found to be below room temperature. Thus, at room temperature and some degrees lower, all the tested springs exert super-elastic properties. For orthodontic treatment this means the maintenance of super-elastic behaviour, even when mouth temperature decreases to about room temperature as can occur, for example, during meals. PMID:10565090

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

1999-10-01

339

Multiple-specimen absolute paleointensity determination with the MSP-DSC protocol: Advantages and drawbacks.  

NASA Astrophysics Data System (ADS)

The MSP-DSC protocol (Dekkers & Bohnel, 2006, EPSL; Fabian & Leonhardt, 2010, EPSL) is a recent development in the methodology for documenting the intensity of the ancient Earth magnetic field. Applicable both on rocks or archaeological artifacts it allows us to use samples that until now were not measured because their magnetic properties do not meet selection criteria required by conventional methods. However, this new experimental protocol requires that samples be heated and cooled under a field parallel to its natural remanent magnetization (NRM). Currently, standard paleointensity furnaces do not match precisely this constraint. Yet, such new measurement protocol seems very promising since it would possibly double the number of available data. We are developing in Montpellier (France), a very fast-heating oven with infrared dedicated to this protocol. Two key points determine its characteristics. The first is to heat uniformly a rock sample of a 10-cc-standard volume as fast as possible. The second is to apply to the sample during the heating (and the cooling) a precise magnetic induction field, perfectly controlled in 3D. We tested and calibrated a preliminary version of this oven along with the MSP-DSC protocol with 3 historical lava flows, 2 from Reunion Island (erupted in 2002 and 2007) and one from Etna (erupted in 1983). These lava flows were selected because they have different magnetic behaviors. Reunion 2002 is rather SD-PSD-like, while Reunion 2007 is PSD-MD-like, and Etna 1983 is MD-like. The paleointensity determinations obtained with the original protocol of Dekkers and Bohnel (2006, EPSL) are within +- 1 ?T of the known field for the three lava flows. The same precision is obtained when we applied the fraction correction (MSP-FC protocol). However, we systematically observed a loss in the linearity of the MSP-FC plots. In addition, like Muxworthy and Taylor (2011, GJI), we found that the Domain State Correction is difficult to apply since alpha = 0 is always found whatever we use an ordinary least square regression or a robust regression. We will present and discuss in this talk some modifications of the MSP-DSC protocol which are currently tested in our laboratory.

Camps, P.; Fanjat, G.; Poidras, T.; Carvallo, C.; Nicol, P.

2012-04-01

340

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

PubMed Central

The application of dynamic susceptibility contrast (DSC) MRI methods to assess brain tumors is often confounded by the extravasation of contrast agent (CA). Disruption of the blood–brain barrier allows CA to leak out of the vasculature leading to additional T1, T2 and T2? relaxation effects in the extravascular space, thereby affecting the signal intensity time course in a complex manner. The goal of this study is to validate a dual-echo DSC-MRI approach that separates and quantifies the T1 and T2? contributions to the acquired signal and enables the estimation of the volume transfer constant, Ktrans, and the volume fraction of the extravascular extracellular space, ?e. To test the validity of this approach, DSC-MRI- and dynamic contrast enhanced (DCE) MRI-derived Ktrans and ?e estimates were spatially compared in both 9L and C6 rat brain tumor models. A high degree of correlation (concordance correlation coefficients >0.83, Pearson's r>0.84) and agreement was found between the DSC-MRI- and DCE-MRI-derived measurements. These results indicate that dual-echo DSC-MRI can be used to simultaneously extract reliable DCE-MRI kinetic parameters in brain tumors in addition to conventional blood volume and blood flow metrics.

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

2012-01-01

341

Hydrogen-induced changes in the properties of Zr-based AB2 alloy studied by x-ray, electrical resistivity and differential scanning calorimetry  

NASA Astrophysics Data System (ADS)

Powder x-ray diffraction and the electrical resistivity of (Ti0.1Zr0.9)1.1Mn0.9V0.1Fe0.5Ni0.5-Hx with different hydrogen concentrations have been investigated and the results have been discussed. An experimental facility has been developed to measure the in situ electrical resistivity of alloys during the hydrogen absorption process. Variation in in situ electrical resistivity with hydrogen concentration in (Ti0.1Zr0.9)1.1Mn0.9V0.1Fe0.5Ni0.5 has been explained using the phase transformation during hydrogen absorption. Differential scanning calorimetry (DSC) studies have been performed in (Ti0.1Zr0.9)1.1Mn0.9V0.1Fe0.5Ni0.5-Hx with different hydrogen concentrations in the temperature range 50-250 °C under argon atmosphere. The DSC studies show that the desorption of hydrogen is from the 24l (A2B2) tetrahedral sites. The activation energies and diffusion coefficients of hydrogen in (Ti0.1Zr0.9)1.1Mn0.9V0.1Fe0.5Ni0.5 have been determined in the range 30-100 °C from the hydrogen absorption kinetics measurements. The diffusion coefficient of hydrogen in (Ti0.1Zr0.9)1.1Mn0.9V0.1Fe0.5Ni0.5-Hx at 30 °C is 1.1 × 10-10 cm2 s-1.

Kandavel, M.; Ramaprabhu, S.

2006-03-01

342

A study of statistical error in isothermal titration calorimetry.  

PubMed

In isothermal titration calorimetry (ITC), the two main sources of random (statistical) error are associated with the extraction of the heat q from the measured temperature changes and with the delivery of metered volumes of titrant. The former leads to uncertainty that is approximately constant and the latter to uncertainty that is proportional to q. The role of these errors in the analysis of ITC data by nonlinear least squares is examined for the case of 1:1 binding, M+X right arrow over left arrow MX. The standard errors in the key parameters-the equilibrium constant Ko and the enthalpy DeltaHo-are assessed from the variance-covariance matrix computed for exactly fitting data. Monte Carlo calculations confirm that these "exact" estimates will normally suffice and show further that neglect of weights in the nonlinear fitting can result in significant loss of efficiency. The effects of the titrant volume error are strongly dependent on assumptions about the nature of this error: If it is random in the integral volume instead of the differential volume, correlated least-squares is required for proper analysis, and the parameter standard errors decrease with increasing number of titration steps rather than increase. PMID:12963058

Tellinghuisen, Joel

2003-10-01

343

Application of pressure perturbation calorimetry to lipid bilayers.  

PubMed Central

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

Heerklotz, Heiko; Seelig, Joachim

2002-01-01

344

Proton Calorimetry and Gamma-Rays in Arp 220  

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

345

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

PubMed

Isothermal titration calorimetry (ITC) is a well-described technique that measures the heat released or absorbed during a chemical reaction, using it as an intrinsic probe to characterize virtually every chemical process. Nowadays, this technique is extensively applied to determine thermodynamic parameters of biomolecular binding equilibria. In addition, ITC has been demonstrated to be able of directly measuring kinetics and thermodynamic parameters (kcat, KM, ?H) of enzymatic reactions, even though this application is still underexploited. As heat changes spontaneously occur during enzymatic catalysis, ITC does not require any modification or labeling of the system under analysis and can be performed in solution. Moreover, the method needs little amount of material. These properties make ITC an invaluable, powerful and unique tool to study enzyme kinetics in several applications, such as, for example, drug discovery. In this work an experimental ITC-based method to quantify kinetics and thermodynamics of enzymatic reactions is thoroughly described. This method is applied to determine kcat and KM of the enzymatic hydrolysis of urea by Canavalia ensiformis (jack bean) urease. Calculation of intrinsic molar enthalpy (?Hint) of the reaction is performed. The values thus obtained are consistent with previous data reported in literature, demonstrating the reliability of the methodology. PMID:24747990

Mazzei, Luca; Ciurli, Stefano; Zambelli, Barbara

2014-01-01

346

Tritium accounting characteristics of `in-bed` gas flowing calorimetry  

SciTech Connect

A scaled ZrCo bed (25 g tritium capacity of design) with gas flowing calorimetry system was fabricated to establish the `in-bed` tritium accounting technology to apply to the ITER tritium storage beds. The basic calorimetric characteristics, steady state temperature raise of He gas stream flowing through a secondary coil line fixed in the ZrCo tritide, was measured and correlated with power input by heater to simulate tritium decay heat or with actual tritium storage. The target accuracy is 1% which means to measure {+-} 1 gram (0.32 watt) of tritium on 100 g storage. The results shows the good accounting function that the temperature increases of He stream of 4.7 and 96.8 degrees were measured under power input of 0.32 and 8.0 watts, respectively, with good reproducibility. These `in-bed` tritium accounting function was well demonstrated storing a gram level of tritium gas within a few days. 8 refs., 7 figs.

Hayashi, T.; Yamada, M.; Suzuki, T.; Matsuda, Y.; Okuno, K. [Tritium Engineering Lab., Ibaraki (Japan)

1995-10-01

347

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

NASA Astrophysics Data System (ADS)

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.

Kök, M.; Aydo?du, Y.

2007-04-01

348

Diguanidinium hydrogenarsenate monohydrate and its deuterated analogue vibrational, DSC and X-ray investigations.  

PubMed

The crystal structure of diguanidinium hydrogenarsenate monohydrate has been found to belong to the P42(1)/c space group of the tetragonal system, with Z = 8, a = 17.114(2) A, c = 7.3500(10) A. In this complex, a network of hydrogen bonds links water molecules and hydrogenarsenate ions. The hydrogenarsenate ions form hydrogen-bonded chains along the crystallographic c-axis. Detailed vibrational studies have been carried out (FTIR and FT-Raman on powder samples, polarized FTIR microscope on a small single crystal at room temperature). The vibrational spectra are discussed in relation to the crystal structure. Calorimetric (DSC) studies have been performed, but no phase transition was found in the temperature range 100-350 K. PMID:16165018

Drozd, M; Baran, J; Pietraszko, A

2005-10-01

349

Strategies for assessing proton linkage to bimolecular interactions by global analysis of isothermal titration calorimetry data  

PubMed Central

Isothermal titration calorimetry (ITC) is a traditional and powerful method for studying the linkage of ligand binding to proton uptake or release. The theoretical framework has been developed for more than two decades and numerous applications have appeared. In the current work, we explored strategic aspects of experimental design. To this end, we simulated families of ITC data sets that embed different strategies with regard to the number of experiments, range of experimental pH, buffer ionization enthalpy, and temperature. We then re-analyzed the families of data sets in the context of global analysis, employing a proton linkage binding model implemented in the global data analysis platform SEDPHAT, and examined the information content of all data sets by a detailed statistical error analysis of the parameter estimates. In particular, we studied the impact of different assumptions about the knowledge of the exact concentrations of the components, which in practice presents an experimental limitation for many systems. For example, the uncertainty in concentration may reflect imperfectly known extinction coefficients and stock concentrations or may account for different extents of partial inactivation when working with proteins at different pH values. Our results show that the global analysis can yield reliable estimates of the thermodynamic parameters for intrinsic binding and protonation, and that in the context of the global analysis the exact molecular component concentrations may not be required. Additionally, a comparison of data from different experimental strategies illustrates the benefit of conducting experiments at a range of temperatures.

Coussens, Nathan P.; Schuck, Peter; Zhao, Huaying

2012-01-01

350

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

PubMed

A comprehensive study on the binding of phenazinium dyes viz. janus green B, indoine blue, safranine O and phenosafranine with double stranded poly(A) using various spectroscopic and calorimetric techniques is presented. A higher binding of janus green B and indoine blue over safranine O and phenosafranine to poly(A) was observed from all experiments. Intercalative mode of binding of the dyes was inferred from fluorescence polarization anisotropy, iodide quenching and viscosity experiments. Circular dichroism study revealed significant perturbation of the secondary structure of poly(A) on binding of these dyes. Results from isothermal titration calorimetry experiments suggested that the binding was predominantly entropy driven with a minor contribution of enthalpy to the standard molar Gibbs energy. The results presented here may open new opportunities in the application of these dyes as RNA targeted therapeutic agents. PMID:24861262

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

2014-10-15

351

Differential scanning calorimetry studies on structural phase transitions and molecular motions in (CH3NH3)2MBr4 and [(CH3)2NH2]2MBr4 (M = Zn, Cd, and Hg)  

NASA Astrophysics Data System (ADS)

Structural phase transitions and molecular motions in (CH3NH3)2MBr4 and in [(CH3)2NH2]2MBr4 (M = Zn, Cd, and Hg) were investigated by differential scanning calorimetry (DSC) between about 130 K and the melting points. All of the compounds showed at least one structural phase transition over the temperature region investigated. The values of the transition entropies obtained suggest that these transitions are of the order-disorder type. N-H...Br hydrogen bonds were found to play an important role in the stability of P21/c room-temperature phases of the title compounds. In the highest-temperature solid phases of all title compounds, orientational orders of cations seem to be completely lost.

Horiuchi, Keizo; Ishihara, Hideta; Terao, Hiromitsu

2000-06-01

352

Aggregation property of glycyrrhizic acid and its interaction with cyclodextrins analyzed by dynamic light scattering, isothermal titration calorimetry, and NMR.  

PubMed

The structural properties of glycyrrhizic acid, a sweet-tasting constituent of Glycyrrhiza glabra, and its interaction with cyclodextrins were analyzed using dynamic light scattering, isothermal titration calorimetry, and NMR. The dynamic light scattering and NMR studies showed that glycyrrhizic acid forms a water-soluble aggregate that disperses upon the addition of ?-cyclodextrin. The high sweetness of glycyrrhizic acid can be closely correlated with this aggregation, because the multimers of glycyrrhizic acid can simultaneously bind to the sweet taste receptors on the human tongue. The isothermal titration calorimetry experiments demonstrated that ?-cyclodextrin binds to glycyrrhizic acid more strongly than ?-cyclodextrin, however, both reactions are accompanied by a favorable change in binding entropy. Considering the large negative change in heat capacity that is observed during the binding of ?-cyclodextrin, the main driving force for the binding is hydrophobic interactions with dehydration, which is typical for inclusion complex. NMR experiments showed that ?-cyclodextrin interacts with the central part of the aglycone moiety, not the glucuronic acid moieties, resulting in high binding affinity. It should also be noted that the two distinct complexes of glycyrrhizic acid with ?-cyclodextrin would exist in aqueous solution. PMID:24844630

Izutani, Yusuke; Kanaori, Kenji; Oda, Masayuki

2014-06-17

353

Influence of size and functionality of polymeric nanoparticles on the adsorption behavior of sodium dodecyl sulfate as detected by isothermal titration calorimetry  

Microsoft Academic Search

Isothermal titration calorimetry was used to monitor the adsorption of the surfactant sodium dodecylsulfate (SDS) on different\\u000a sized pure and carboxy functionalized polystyrene nanoparticles prepared by the mini-emulsion process. The ITC experiment\\u000a gives, additionally to the CMC values, information about the interaction of the surfactant molecules to the particle’s surface\\u000a due to the particle surface properties. The adsorption heat depends

Anika Hamberger; Katharina Landfester

2011-01-01

354

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

NASA Astrophysics Data System (ADS)

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

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

2000-05-01

355

DSC investigation of the effect of the new sigma ligand PPCC on DMPC lipid membrane.  

PubMed

The new sigma ligand cis-(±)-methyl (1R,2S/1S,2R)-2-[(4-hydroxy-4-phenylpiperidin-1-yl) methyl]-1-(4-methylphenyl) cyclopropanecarboxylate [(±)-PPCC] is a promising tool for the treatment of various diseases. With the aim to investigate the absorption of (±)-PPCC by the cell membranes, in this study we evaluated the influence on thermotropic behavior of membrane model exerted by PPCC both as free base or as oxalic salt. To fulfill this purpose differential scanning calorimetry was used. The findings highlight that PPCC affects the thermodynamic parameters of phospholipids in different manner depending on whether it is in the salt or base form as well as function of the amount of drugs dispersed in the lipid matrix. The salt form of PPCC was uptaken by the membrane model faster than the free base. In addition, preliminary information on the use of a lipophilic carrier for PPCC was obtained. PMID:24768402

Sarpietro, Maria Grazia; Accolla, Maria Lorena; Cova, Annamaria; Prezzavento, Orazio; Castelli, Francesco; Ronsisvalle, Simone

2014-07-20

356

Calorimetry in Medical Applications: Single-Photon Emission Computed Tomography and Positron Emission Tomography  

SciTech Connect

Positron emission tomography (PET) and single-photon emission computed tomography (SPECT), two nuclear medicine imaging modalities broadly used in clinics and research, share many common instrumentation, detector, and electronics technology platforms with calorimetry in high-energy physics, astronomy, and other physics sciences. Historically, advances made in calorimetry had played major roles in the development of novel approaches and critical technologies essential to the evolution of PET and SPECT. There have also been examples in which PET/SPECT developments had led to new techniques in calorimetry for other application areas. In recent years, several innovations have propelled advances in both calorimetry in general and PET/SPECT in particular. Examples include time-of-flight (TOF) measurements, silicon photomultipliers (SiPMs), etc.

Chen, C.-T. [Department of Radiology, University of Chicago, Chicago, Illinois 60637 (United States); Committee on Medical Physics, University of Chicago, Chicago, Illinois 60637 (United States)

2006-10-27

357

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

ERIC Educational Resources Information Center

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

Temme, Susan M.

1995-01-01

358

An Integrated-Circuit Temperature Sensor for Calorimetry and Differential Temperature Measurement.  

ERIC Educational Resources Information Center

Describes the application of an integrated-circuit (IC) chip which provides an easy-to-use, inexpensive, rugged, computer-interfaceable temperature sensor for calorimetry and differential temperature measurement. Discusses its design and advantages. (JRH)

Muyskens, Mark A.

1997-01-01

359

Amorphization and Related Effects in Ni/Ti Multilayers Studied by Differential Scanning Calorimetry.  

National Technical Information Service (NTIS)

Ni/Ti multilayers of three different gross compositions, all having a composition modulation wavelength of approximately 20 nm, were studied by differential scanning calorimetry. In order to associate the observed heat effects with phase transitions, dupl...

M. A. Hollanders B. J. Thijsse E. J. Mittemeijer

1990-01-01

360

Ultra-stable temperature control in EPR experiments: Thermodynamics of gel-to-liquid phase transition in spin-labeled phospholipid bilayers and bilayer perturbations by spin labels  

NASA Astrophysics Data System (ADS)

An ultra-stable variable temperature accessory for EPR experiments with biological samples has been designed and tested. The accessory is comprised from a digitally controlled circulator bath that pumps fluid through high-efficiency aluminum radiators attached to an EPR resonator of a commercial X-band EPR spectrometer. Temperature stability of this new accessory after a 15 min re-equilibration is at least ±0.007 K. For a standard 1-cm-long capillary sample arranged inside an EPR tube filled with silicon oil, the temperature variations do not exceed ±0.033 K over the sample temperature range from 283 to 333 K. This new accessory has been tested by carrying out a comparative spin-labeling EPR and differential scanning calorimetry (DSC) study of the gel-to-liquid phase transition in multilamellar vesicles (MLV) composed of a synthetic phospholipid 1,2-dimyristoyl- sn-glycero-3-phosphatidylcholine (DMPC). We demonstrate that the gel-to-liquid phase transition temperatures of MLV DMPC measured by EPR and DSC agree within ±0.02 K experimental error even though the sample for EPR study was labeled with 1 mol% of 5PC (1-palmitoyl-2-stearoyl-(5-doxyl)- sn-glycero-3 phosphocholine). Cooperative unit number measured by EPR, N = 676 ± 36, was almost 50% higher than that obtained from DSC ( N = 458 ± 18). These high values of N indicate that (i) the lipid domains should include at least several spin-labeled lipid molecules and (ii) the spin-probe 5PC molecules are not excluded into domains that are different from the bulk lipid phase as was speculated earlier. Overall, our data provide DSC and EPR evidence that in studies of the gel-to-liquid phase transition, the effect of bilayer perturbation by spin-labeled lipids is negligible and therefore thermodynamic parameters of the phase transition can be accurately measured by spin-labeling EPR. This might serve as an indication when spin-labeled molecules with structures similar to those of lipids are introduced at low concentrations, they are easily accommodated by fluid phospholipid bilayers without significant losses of the lipid cooperativity.

Alaouie, Ali M.; Smirnov, Alex I.

2006-10-01

361

Enthalpies of formation of Zr–Au compounds determined by direct reaction calorimetry  

Microsoft Academic Search

The enthalpies of formation of Zr(1?x)Aux compounds, (x =1\\/4, 1\\/3, 4\\/9, 1\\/2, 10\\/17, 2\\/3, 3\\/4, 4\\/5) have been measured by direct reaction calorimetry with reference to pure metals taken in their solid states. Mixing calorimetry, solid Zr in liquid Au, was performed at 1473 K. The results are compared to earlier experimental data and values predicted from Miedema's model.

M. Lomello-Tafin; P. Galez; P. Feschotte; J. J. Kuntz; J. L. Jorda; J. C. Gachon

1998-01-01

362

Use of reaction calorimetry to monitor and control microbial cultures producing industrially relevant secondary metabolites  

Microsoft Academic Search

In this article, bench-scale heat flux calorimetry is applied to monitor complex microbial systems producing secondary metabolites and having a rheologically complex behavior. With such systems, biological metabolic activity can only be measured accurately if calorimetry is improved by on-line correction for stirring power variations using torque measurement.First, a successful application to the production of the antibiotic erythromycin by Saccharopolyspora

D. Voisard; C. Claivaz; L. Menoud; I. W. Marison; U. von Stockar

1998-01-01

363

Proceedings of the Eleventh International Conference on Calorimetry in Particle Physics  

NASA Astrophysics Data System (ADS)

The Pamela silicon tungsten calorimeter / G. Zampa -- Design and development of a dense, fine grained silicon tungsten calorimeter with integrated electronics / D. Strom -- High resolution silicon detector for 1.2-3.1 eV (400-1000 nm) photons / D. Groom -- The KLEM high energy cosmic rays collector for the NUCLEON satellite mission / M. Merkin (contribution not received) -- The electromagnetic calorimeter of the Hera-b experiment / I. Matchikhilian -- The status of the ATLAS tile calorimeter / J. Mendes Saraiva -- Design and mass production of Scintillator Pad Detector (SPD) / Preshower (PS) detector for LHC-b experiment / E. Gushchin -- Study of new FNAL-NICADD extruded scintillator as active media of large EMCal of ALICE at LHC / O. Grachov -- The CMS hadron calorimeter / D. Karmgard (contribution not received) -- Test beam study of the KOPIO Shashlyk calorimeter prototype / A. Poblaguev -- The Shashlik electro-magnetic calorimeter for the LHCb experiment / S. Barsuk -- Quality of mass produced lead-tungstate crystals / R. Zhu -- Status of the CMS electromagnetic calorimeter / J. Fay -- Scintillation detectors for radiation-hard electromagnetic calorimeters / H. Loehner -- Energy, timing and two-photon invariant mass resolution of a 256-channel PBWO[symbol] calorimeter / M. Ippolitov -- A high performance hybrid electromagnetic calorimeter at Jefferson Lab / A. Gasparian -- CsI(Tl) calorimetry on BESHI / T. Hu (contribution not received) -- The crystal ball and TAPS detectors at the MAMI electron beam facility / D. Watts -- Front-end electronics of the ATLAS tile calorimeter / R. Teuscher -- The ATLAS tilecal detector control system / A. Gomes -- Performance of the liquid argon final calibration board / C. de la Taille -- Overview of the LHCb calorimeter electronics / F. Machefert -- LHCb preshower photodetector and electronics / S. Monteil -- The CMS ECAL readout architecture and the clock and control system / K. Kloukinas -- Test of the CMS-ECAL trigger primitive generation / N. Regnault -- Optical data links for the CMS ECAL / J. Grahl (contribution not received) -- CMS ECAL off-detector electronics / R. Alemany Fernandez -- Performance of a low noise readout ASIC for the W-Si calorimeter physics prototype for the future linear collider / C. de la Taille -- Properties of a sampling calorimeter with warm-liquid ionization chambers / S. Plewnia -- Calorimetry and the DO experiment / R. Zitoun (contribution not received) -- Data quality monitoring for the DØ calorimeter / V. Shary -- Status of the construction of the ATLAS electromagnetic liquid argon calorimeter, overview of beam test performance studies / L. Serin -- Uniformity of response of ATLAS liquid argon EM calorimeter / O. Gaunter -- Status of the ATLAS liquid argon hadronic endcap calorimeter construction / M. Vincter -- Results from particle beam tests of the ATLAS liquid argon endcap calorimeters / M. Lefebvre -- First results of the DREAM project / R. Wigmans -- Electron and muon detection with a dual-readout (DREAM) calorimeter / N. Akchurin -- The neutron zero degree calorimeter for the ALICE experiment / M. Gallio -- The liquid xenon scintillation calorimeter of the MEG experiment: operation of a large prototype / G. Signorelli -- Detection of high energy particles using radio frequency signals / C. Hebert -- Hadronic shower simulation / J.-P. Wellisch -- E.M. and hadronic shower simulation with FLUKA / G. Battistoni -- Simulation of the LHCb electromagnetic calorimeter response with GEANT4 / P. Robbe -- Comparison of beam test results of the combined ATLAS liquid argon endcap calorimeters with GEANT3 and GEANT4 simulations / D. Salihagi? -- GEANT4 hadronic physics validation with LHC test-beam data / C. Alexa -- The full simulation of the GLAST LAT high energy gamma ray telescope / F. Longo -- Response of the KLOE electromagnetic calorimeter to low-energy particles / T. Spadaro -- Calorimeter algorithms for DØ; / S. Trincaz-Duvoid -- Identification of low P[symbol] muon with the ATLAS tile calorimeter / G. Usai -- Electron and photon reconstruction

Cecchi, Claudia

364

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

PubMed Central

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.

Aweda, Tolulope A.; Meares, Claude F.

2011-01-01

365

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

NASA Astrophysics Data System (ADS)

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.

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

2010-06-01

366

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

ERIC Educational Resources Information Center

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

Haugen, Richard

1978-01-01

367

Advanced monolithic active pixel sensors for tracking, vertexing and calorimetry with full CMOS capability  

NASA Astrophysics Data System (ADS)

We present test results from the "TPAC" and "F ORTIS" sensors produced using the 180 nm CMOS INMAPS process. The TPAC sensor has a 50 ?m pixel size with advanced in-pixel electronics. Although TPAC was developed for digital electromagnetic calorimetry, the technology can be readily extended to tracking and vertexing applications where highly granular pixels with in-pixel intelligence are required. By way of example, a variant of the TPAC sensor has been proposed for the Super B vertex detector. The F ORTIS sensor is a prototype with several pixel variants to study the performance of a four transistors (4T) architecture and is the first sensor of this type tested for particle physics applications. TPAC and F ORTIS sensors have been fabricated with some of the processing innovations available in INMAPS such as deep p-wells and high-resistivity epitaxial layers. The performance of these sensor variants has been measured both in the laboratory and at test beams and results showing significant improvements due to these innovations are presented. We have recently manufactured the "C HERWELL" sensor, building on the experience with both TPAC and F ORTIS and making use of the 4T approach. C HERWELL is designed for tracking and vertexing and has an integrated ADC and targets very low-noise performance. The principal features of C HERWELL are described.

Stanitzki, M.; SPiDeR Collaboration, www. spider. ac. uk

2011-09-01

368

Evaluation of linked protonation effects in protein binding reactions using isothermal titration calorimetry.  

PubMed Central

A theoretical development in the evaluation of proton linkage in protein binding reactions by isothermal titration calorimetry (ITC) is presented. For a system in which binding is linked to protonation of an ionizable group on a protein, we show that by performing experiments as a function of pH in buffers with varying ionization enthalpy, one can determine the pK(a)'s of the group responsible for the proton linkage in the free and the liganded states, the protonation enthalpy for this group in these states, as well as the intrinsic energetics for ligand binding (delta H(o), delta S(o), and delta C(p)). Determination of intrinsic energetics in this fashion allows for comparison with energetics calculated empirically from structural information. It is shown that in addition to variation of the ligand binding constant with pH, the observed binding enthalpy and heat capacity change can undergo extreme deviations from their intrinsic values, depending upon pH and buffer conditions. Images FIGURE 6 FIGURE 7 FIGURE 9

Baker, B M; Murphy, K P

1996-01-01

369

Size and rate dependence of crystal nucleation in single tin drops by fast scanning calorimetry.  

PubMed

The experimentally accessible degree of undercooling of single micron-sized liquid pure tin drops has been studied via differential fast scanning calorimetry. The cooling rates employed ranged from 100 to 14,000 K/s. The diameter of the investigated tin drops varied in the range from 7 to 40 ?m. The influence of the drop shape on the solidification process could be eliminated due to the nearly spherical shape of the single drop upon heating and cooling and the resultant geometric stability. As a result it became possible to study the effect of both drop size and cooling rate in rapid solidification experimentally. A theoretical description of the experimental results is given by assuming the existence of two different heterogeneous nucleation mechanisms leading to crystal nucleation of the single tin drop. In agreement with the experiment these mechanisms yield a shelf-like dependence of crystal nucleation on undercooling. A dependence of crystal nucleation on the size of the tin drop was observed and is discussed in terms of the mentioned theoretical model, which can possibly also describe the nucleation for other related rapid solidification processes. PMID:23406127

Yang, Bin; Abyzov, A S; Zhuravlev, E; Gao, Yulai; Schmelzer, J W P; Schick, C

2013-02-01

370

Size and rate dependence of crystal nucleation in single tin drops by fast scanning calorimetry  

NASA Astrophysics Data System (ADS)

The experimentally accessible degree of undercooling of single micron-sized liquid pure tin drops has been studied via differential fast scanning calorimetry. The cooling rates employed ranged from 100 to 14 000 K/s. The diameter of the investigated tin drops varied in the range from 7 to 40 ?m. The influence of the drop shape on the solidification process could be eliminated due to the nearly spherical shape of the single drop upon heating and cooling and the resultant geometric stability. As a result it became possible to study the effect of both drop size and cooling rate in rapid solidification experimentally. A theoretical description of the experimental results is given by assuming the existence of two different heterogeneous nucleation mechanisms leading to crystal nucleation of the single tin drop. In agreement with the experiment these mechanisms yield a shelf-like dependence of crystal nucleation on undercooling. A dependence of crystal nucleation on the size of the tin drop was observed and is discussed in terms of the mentioned theoretical model, which can possibly also describe the nucleation for other related rapid solidification processes.

Yang, Bin; Abyzov, A. S.; Zhuravlev, E.; Gao, Yulai; Schmelzer, J. W. P.; Schick, C.

2013-02-01

371

Immersion calorimetry of fine coal particles and its relation to flotation  

SciTech Connect

A Setaram C-80 heat flux microcalorimeter was used to study the surface and interfacial properties of fine coal particles in water containing flotation agents via heat of immersion measurements. Heat of immersion (..delta..H/sub imm/) is usually a small exothermic quantity and can be used to characterize a solid in terms of its relative hydrophobicity or hydrophilicity. The effects of coal type, surface oxidation, mineral matter content, kerosene concentration, and pH on the wetting characteristics were investigated. Although coal is a heterogeneous mixture of organic and inorganic materials, immersional calorimetry has proven to be quite helpful in measuring surface properties of coal, and the following conclusions can be drawn: The heat of immersion decreased with increasing kerosene concentration, which corresponds to the coal particles increasing hydrophobicity; in varying the pH, the ..delta..H/sub imm/ went through a minimum at a pH value of 6.5 to 7.0, which coincides with the reported optimum pH range for flotation; both oxidation and clay slime coating (addition of kaolin), which are known to make the coal less hydrophobic, increased the ..delta..H/sub imm/; and the trends that were shown to exist in the heat of immersion measurements (for varying kerosene concentration, pH oxidation, and clay slime coating) correlated well with independent flotation experiments. 16 refs., 6 figs., 2 tabs.

Melkus, T.G.; Chiang, S.H.; Wen, W.W.

1987-01-01

372

Adiabatic Calorimetry Approach to Assess Thermal Influences on the Indium Melting Point  

NASA Astrophysics Data System (ADS)

Within the framework of the Euramet project 732, LCM/LNE-CNAM has recently proposed a new device to investigate the melting point of indium (156.5985 °C) by the way of an adiabatic calorimetry approach. An apparatus based on a cell-within-cell configuration was developed and experimentally tested. First results highlighted parasitic heat flows due to the geometrical characteristics of the cell, disturbing significantly the isothermal condition within the calorimeter. Such thermal effects were also clearly identified with a specific numerical model developed for this purpose. Considering the remarkable agreement between the model and relevant experiments, an optimization step has been carried out to design a suitable cell geometry. A new enhanced cell was subsequently fabricated and arranged within the calorimeter (indium load of 122.32 g). The purpose of this article is to introduce the thermal behavior of such a highly effective apparatus, while presenting some series of measurements; on the one hand, the melting point of indium under adiabatic conditions is studied, and on the other hand, the so-called continuous heat flow method under isothermal conditions is worked out. The obtained results are discussed and analyzed according to the impurity concentrations into the ingot (sum of individual estimate method).

Failleau, G.; Fleurence, N.; Morice, R.; Gaviot, E.; Rénaot, E.

2010-09-01

373

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

PubMed

Carotenoids are the effective modulators of physical properties of model and natural membranes. To demonstrate the relationship between the structure of carotenoids and their effect on the molecular dynamics of membranes, we have investigated the influence of five structurally different carotenoids: beta-carotene, lycopene, lutein, violaxanthin, zeaxanthin and additionally carotane--a fully saturated derivative of beta-carotene, on thermotropic phase behaviour of dipalmitoylphosphatidylcholine (DPPC) multilamellar vesicles by means of differential scanning calorimetry (DSC). The results obtained indicate that the carotenoids used modulated the thermotropic properties of multibilayers to various extents, broadening the pretransition and the main phase transition peaks and shifting them to lower temperatures. Pronounced decrease of pretransition enthalpy (DeltaH(p)) proves that carotenoids very strongly alter the membrane properties in its gel phase. Comparison of the influence of several carotenoids shows that a rigid, polyisoprenoid chain plays a basic role in altering the thermotropic properties of such membranes and the presence of rings without oxygen-containing groups has a minor significance for the observed interactions. Carotenoids containing epoxy and/or hydroxy groups attached to their rings modify the thermotropic phase behaviour of DPPC multilamellar vesicles stronger than carotenes--a result of their orientation in the DPPC bilayer. PMID:12543381

Kostecka-Guga?a, Anna; Latowski, Dariusz; Strza?ka, Kazimierz

2003-01-31

374

AC calorimetry of Quasi-one-dimensional materials  

NASA Astrophysics Data System (ADS)

There has been continuing interest in quasi-one-dimensional materials for decades. Their one-dimensional nature gives rise to many unusual properties such as spin-density waves, charge-density waves, spin-Peierls transitions, glassy behavior, and large fluctuation effects. We study these phase transitions by measuring resistance, specific heat, and Young's moduli, among other properties. We have measured the specific heat of small (˜1 mg) single crystalline flakes of alpha'-NaV2O5. The size of the peak (Deltacp ˜ R) is more than an order of magnitude greater than the value estimated from mean-field theory. The specific heat and Young's modulus anomalies are very large and sample dependent. Subsequent work has shown that NaV2O5 does not go through a spin-Peierls transition as was first thought. It is generally believed that this is a charge order phase transition, with a transformation into a spin gap singlet state We have measured the specific heat of single crystals of TSeF-TCNQ. Anomalies are observed at Ta = 28K and Tb = 33K, indicating that there are two phase transitions, presumably reflecting the separate condensation of the charge-density wave on the TSeF and TCNQ conducting chains. We built an ac Joule calorimeter to measure the specific heats of materials from 1K to 10K. Pumping on liquid helium allowed us to operate at any temperatures between 1K and 4.2K. Oscillating power was applied to the sample with a thin film resistor attached directly to the sample. The magnitude of the oscillating temperature is inversely proportional to the heat capacity when certain experimental conditions are met. We have searched for dynamic thermal effects in (TMTSF)2PF 6 by measuring its specific heat with ac calorimetry. Near its spin-density wave transition (Tc = 12K), the magnitude of the specific heat is the same as that measured in quasi static measurements, indication that there are no kinetic contributions to the specific heat at these temperatures. No anomalies are observed in a pellet of (TMTSF)2PF6 mixed with KBr at Tc or the expected "spin-density wave glass" transition (Tg ˜ 3.5K), suggesting that residual disorder in the pellet freezes in a glassy state at Tc.

Powell, David Kennedy

375

Structure and phase transition in bis(pyrrolidinium) hexachlorometallates, (C 4H 8NH 2) 2MCl 6 (M=Sn, Te and Pt), studied by X-ray diffraction, 35Cl NQR and DSC  

NASA Astrophysics Data System (ADS)

Single crystal X-ray diffraction, 35Cl nuclear quadrupole resonance (NQR) and differential scanning calorimetry (DSC) measurements were taken for bis(pyrrolidinium) hexachlorometallates, (C 4H 8NH 2) 2MCl 6 (M=Sn, Te and Pt). A solid-solid phase transition was observed at 150(1), 159(1) and 134(1) K for stannate, tellurate and platinate, respectively. 35Cl NQR signals were observed in stannate and platinate, both of which showed a two-line spectrum in the high-temperature phase and a three-line spectrum in the low-temperature phase. The high-temperature phases of the three complexes were found to be isostructural with each other belonging to the space group C2/ m (#12). The C 4H 8NH 2+ and MCl 62- ions are connected by N-H⋯Cl hydrogen bonds forming parallel sheets in the crystals. Disorder of the cation ring appears in these high-temperature phases. Semi-empirical MO calculations were performed to estimate the stable structure of the pyrrolidinium ion.

Ishida, H.; Furukawa, Y.; Sato, S.; Kashino, S.

2000-06-01

376

Role of the DSC1 Channel in Regulating Neuronal Excitability in Drosophila melanogaster: Extending Nervous System Stability under Stress  

PubMed Central

Voltage-gated ion channels are essential for electrical signaling in neurons and other excitable cells. Among them, voltage-gated sodium and calcium channels are four-domain proteins, and ion selectivity is strongly influenced by a ring of amino acids in the pore regions of these channels. Sodium channels contain a DEKA motif (i.e., amino acids D, E, K, and A at the pore positions of domains I, II, III, and IV, respectively), whereas voltage-gated calcium channels contain an EEEE motif (i.e., acidic residues, E, at all four positions). Recently, a novel family of ion channel proteins that contain an intermediate DEEA motif has been found in a variety of invertebrate species. However, the physiological role of this new family of ion channels in animal biology remains elusive. DSC1 in Drosophila melanogaster is a prototype of this new family of ion channels. In this study, we generated two DSC1 knockout lines using ends-out gene targeting via homologous recombination. DSC1 mutant flies exhibited impaired olfaction and a distinct jumpy phenotype that is intensified by heat shock and starvation. Electrophysiological analysis of the giant fiber system (GFS), a well-defined central neural circuit, revealed that DSC1 mutants are altered in the activities of the GFS, including the ability of the GFS to follow repetitive stimulation (i.e., following ability) and response to heat shock, starvation, and pyrethroid insecticides. These results reveal an important role of the DSC1 channel in modulating the stability of neural circuits, particularly under environmental stresses, likely by maintaining the sustainability of synaptic transmission.

Zhang, Tianxiang; Wang, Zhe; Wang, Lingxin; Luo, Ningguang; Jiang, Lan; Liu, Zhiqi; Wu, Chun-Fang; Dong, Ke

2013-01-01

377

Complex Heat Capacity of Lithium Borate Glasses Studied by Modulated DSC  

SciTech Connect

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.

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

378

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

379

Study of thermal decomposition of methyl ethyl ketone peroxide using DSC and simulation.  

PubMed

Methyl ethyl ketone peroxide (MEKPO) is a typical organic peroxide with thermally unstable nature that has been broadly employed in the manufacturing process of acrylic resins, as a hardening agent for fiberglass-reinforced plastics, and as a curing agent for unsaturated polyester resins. The aim of this study was to identify the characteristics of MEKPO 31 wt.% while mixing with contaminants, such as H(2)SO(4), HCl, and NaCl under runaway conditions. To acquire the thermal runaway data, DSC and a simulation were used for thermal analysis. The results showed that the thermal decomposition of MEKPO and MEKPO+H(2)SO(4) follows two stages. The first one can be modeled by using an empirical nth order rate equation. The second stage can be modeled as autocatalytic. MEKPO+HCl and MEKPO+NaCl included two independent autocatalytic reactions. The decomposition of MEKPO in the presence of Cl- ions (added in MEKPO either in the form of HCl or NaCl) follows a significantly different path, an earlier decomposition "onset" temperature, higher amount of generated thermal power and smaller temperature of no return (T(NR)) and time to maximum rate (TMR) values. Simulations based on experimental data indicated that the effect of H(2)SO(4) was the most dangerous contaminant on MEKPO 31 wt.%. However, the impact of Cl ions was also important. It is therefore recommended that the means of fire fighting employed for this substance to be free of Cl-. PMID:16905247

Tseng, Jo-Ming; Chang, Ying-Yu; Su, Teh-Sheng; Shu, Chi-Min

2007-04-11

380

SAXS/DSC/WAXD study of temperature evolution in nanocomposite polymer electrolytes with different nanofillers.  

PubMed

Polymer electrolytes are nanostructured materials which are very attractive components for batteries and opto-electronic devices. (PEO)8ZnCl2 polymer electrolytes were prepared from PEO and ZnCl2. The nanocomposites (PEO)8ZnCI2 themselves contained TiO2, Al2O3, MgO, ZnO and V2O5 nanograins. In this work, the influence of the Al2O3, MgO and V2O5 nanograins on the morphology and ionic conductivity of the nanocomposite was systematically studied by transmission small-angle X-ray scattering simultaneously recorded with wide-angle X-ray diffraction and differential scanning calorimetry at the synchrotron ELETTRA (Trieste, Italy). These three measurement methods yielded insight into the temperature-dependent changes of the grains of the electrolyte. The heating and cooling rate was 0.5 degrees C/min. Environment friendly galvanic cells as well as solar cells of the second generation are to be constructed with such nanocomposite polymer as electrolyte. PMID:23421266

Turkovi?, A; Dubcek, P; Jurai?, K; Bernstorff, S

2012-11-01

381

Transfer kinetics from colloidal drug carriers and liposomes to biomembrane models: DSC studies  

PubMed Central

The release of bioactive molecules by different delivery systems has been studied. We have proposed a protocol that takes into account a system that is able to carry out the uptake of a bioactive molecule released during the time, resembling an in vivo-like system, and for this reason we have used biomembrane models represented by multi-lamellar and unilamellar vesicles. The bioactive molecule loaded delivery system has been put in contact with the biomembrane model and the release has been evaluated, to consider the effect of the bioactive molecule on the biomembrane model thermotropic behavior, and to compare the results with those obtained when a pure drug interacts with the biomembrane model. The differential scanning calorimetry technique has been employed. Depending on the delivery system used, our research permits to evaluate the effect of different parameters on the bioactive molecule release, such as pH, drug loading degree, delivery system swelling, crosslinking agent, degree of cross-linking, and delivery system side chains.

Sarpietro, Maria Grazia; Castelli, Francesco

2011-01-01

382

Thermal Decomposition of 2,5-Dipicryl-1,3,4-Oxadiazole, Near its Ignition Temperature: An Isothermal DSC Study.  

National Technical Information Service (NTIS)

2,5-Dipicryl-1,3,4-oxadiazole (DPO) is a thermally stable, high impulse shock sensitive explosive which decomposes in the solid state at a rate easily followed by isothermal differential scanning calorimetry between 575 K (302 deg C) and 598 K (325 deg C)...

D. J. Whelan M. R. Fitzgerald

1994-01-01

383

DSC and Optical Texture Studies of Copolymers Based on Poly(butyleneterephthalate)\\/PHBA and PET\\/PHBA  

Microsoft Academic Search

Copolyesters based on poly(butyleneterephthalate) (PBT) and p-hydroxybenzoic acid (PHBA) wereobtained by transesterification in the melt and the resulting products were characterized as to theirliquid crystalline properties. Thermal transitions and the mesophases formed during heating and coolingwere examined by differential scanning calorimetry and hot stage polarizing microscopy. All the polymermelts were strongly birefringent and showed nematic threaded optical textures, accompanied by

K. Goranov; S. Fakirov; H. P. Hinov; A. Zheliaskova

1989-01-01

384

A new analyzing method of temperature modulated DSC of exo- or endo-thermic process: Application to polyethylene crystallization  

Microsoft Academic Search

A new method is presented to analyse an exothermic or endothermic process with temperature modulated differential scanning calorimetry. The response of exo- or endo-thermic process against temperature modulation has been directly taken into account in an apparent heat capacity difference of complex quantity. Utilizing the shift in phase lag between sample temperature and heat flow, the specific heat during the

Akihiko Toda; Tatsuro Oda; Masamichi Hikosaka; Yasuo Saruyama

1997-01-01

385

Electrical conductivity, DSC, XRD, and 7Li NMR studies of rotator crystals n-C21H43COOLi x K(1 - x) (0.33 ? x ? 0.50), n-C m H(2 m + 1)COOLi, and n-C m H(2 m + 1)COOK ( m = 13, 15, 17, 19, and 21)  

NASA Astrophysics Data System (ADS)

Differential scanning calorimetry (DSC) thermograms, X-ray diffraction (XRD) analysis, electrical conductivity ( ?), and 7Li NMR spectroscopy characterization of n-C m H(2 m + 1)COOM solids (M = Li, Na, K; m = 13, 15, 17, 19, 21) and mixed crystals n-C21H43COOLi x K(1 - x) (0.25 ? x ? 0.75) was performed as a function of temperature. DSC thermograms of n-C m H(2 m + 1)COOM revealed several solid-solid phase transitions with large entropy changes. Electrical conductivity studies established that n-C m H(2 m + 1)COOLi crystals are poor electrical conductors. In contrast, n-C m H(2 m + 1)COOK salts were found to have ? values of 10 - 7-10 - 8 S·cm - 1. Since the crystal structures and phase-transition temperatures of both n-C m H(2 m + 1)COOLi and n-C m H(2 m + 1)COOK crystals were similar, they were able to form mixed crystals with the structure n-C x H(2 m + 1)COOLi x K(1 - x). DSC thermograms of the mixed crystals showed a small entropy change at the melting point (? S mp < 13 J K - 1 mol - 1), in addition, large ? S values at the solid-solid phase transition temperature. The ? values obtained for mixed crystals were roughly one order of magnitude greater than those determined for n-C21H43COOK crystals. 7Li NMR spectra of the mixed crystals recorded at various temperatures suggested that the self-diffusion of Li + ions was excited in the highest-temperature solid phase. Based on these results, we have classified these mixed crystals as rotator crystals.

Hayasaki, Tomoyuki; Honda, Hisashi; Hirakawa, Satoru

2013-05-01

386

Water properties in the super-salt-resistive gel probed by NMR and DSC.  

PubMed

The so-called "super-salt-resistive gel", or poly(4-vinylphenol) (P4VPh) hydrogel, of different water contents ( H = 97-51%) was prepared by cross-linking with different amounts of ethylene glycol diglycidyl ether. 1H NMR spectroscopy was used to investigate the dynamic properties of water in the gel samples in terms of the spin-spin relaxation. The T2 values in those hydrogels were analyzed by assuming a two-component system, namely, T 2(long) and T2(short), and their fractions were obtained. In the higher water content region (75% < or = H < or = 97%), T2(long) for P4VPh gel was almost constant or even slightly increased with decreasing temperature. On the other hand, T2(long) for poly(vinyl alcohol) (PVA) gel (80% < or = H < or = 96%) significantly decreased with decreasing temperature, showing a natural behavior for water mobility in common hydrogels. Water in P4VPh gels of lower water contents ( H = 70% and 51%) also showed intriguing behaviors: the T2 values are much larger than those of gels with higher water contents and decreased with decreasing temperature only in the lower temperature range (<10 degrees C). The fraction of T2(long) values of P4VPh gel showed another contrast to those of PVA gel; the latter decreased with decreasing water content (normal behavior), while in the former gel the highest fraction (ca. 60% at 20 degrees C) was observed for a sample with the lowest water content ( H = 51%). On the other hand, the results of DSC measurements for P4VPh gel were less specific than those of T2 and comparable to those of common hydrogels such as PVA; with decreasing water content, the total amounts of free water and freezable bound water per polymer mass (g/g) decreased, while the amount of nonfreezing water per polymer also decreased. PMID:18537280

Sakai, Yuko; Kuroki, Shigeki; Satoh, Mitsuru

2008-06-01

387

Determination of heat transfer coefficients at the polymer-mold-interface for injection molding simulation by means of calorimetry  

NASA Astrophysics Data System (ADS)

Appropriate modeling of heat transfer from the polymer material to the injection mold is essential to achieve accurate simulation results. The heat transfer is commonly modeled using convective heat transfer and applying heat transfer coefficients (HTC) to the polymer-mold-interface. The set HTC has an influence on the results for filling pressure, cooling performance and shrinkage, among others. The current paper, presents a new strategy to measure HTC in injection molding experiments using Newtons law of cooling. The heat flux is calculated out of demolding heat (measured by means of calorimetry), injection heat (measured by means of an IR-sensor), cooling time and part mass. Cavity surface area, average mold surface temperature and average part surface temperature lead to the HTC.

Stricker, M.; Steinbichler, G.

2014-05-01

388

Cloning of the cDNA (DSC1) coding for human type 1 desmocollin and its assignment to chromosome 18  

SciTech Connect

Desmosomes are adhesive epithelial junctions that contain two distinct classes of cadherin-related glycoproteins (desmogleins and desmocollins), both of which occur as several different isoforms whose expression is related to epithelial differentiation. The authors have now isolated cDNA clones encoding a human desmocollin that is expressed in the more differentiated layers of human epidermis. The isoform has 53% amino acid identity with the previously isolated human (type 3) desmocollin, which is expressed in the basal layers of the epidermis. However, the N- and C-termini of the mature proteins are more highly conserved. Using a panel of somatic cell hybrids, human type 1 desmocollin (gene DSC1) has been assigned to chromosome 18, the same location as the other desmocollin gene (DSC3) and the three desmoglein (DSG) genes already mapped. 49 refs., 5 figs., 1 tab.

King, I.A.; Buxton, R.S. (National Institute for Medical Research, London (United Kingdom)); Spurr, N.K.; Arnemann, J. (Clare Hall Labs., Hertfordshire (United Kingdom))

1993-11-01

389

Determination of gel and vitrification times of thermoset curing process by means of TMA, DMTA and DSC techniques  

Microsoft Academic Search

In the present work, gelation and vitrification experimental data are obtained by TMA and DMTA techniques using the same thermoset\\u000a based on an epoxy-amine system. The results show that the times obtained are not equivalent and depend on the technique used.\\u000a An attempt has been made to compare both determinations using the degree of cure obtained by means of DSC

A. Cadenato; J. M. Salla; X. Ramis; J. M. Morancho; L. M. Marroyo; J. L. Martin

1997-01-01

390

Curing kinetics and mechanisms of polysulfone nanofibrous membranes toughened epoxy\\/amine systems using isothermal DSC and NIR  

Microsoft Academic Search

Curing kinetics and mechanisms of polysulfone nanofibrous membranes toughened TGDDM\\/DDS were investigated by using isothermal DSC and NIR, and compared to those of TGDDM\\/DDS and PSF films toughened TGDDM\\/DDS. At early curing stage, the curing rate of nanofibrous membranes toughened system was faster than those of other two systems, whereas the final conversion of toughened systems was lower than that

Gang Li; Zhibin Huang; Peng Li; Chunling Xin; Xiaolong Jia; Binghui Wang; Yadong He; Seungkon Ryu; Xiaoping Yang

2010-01-01

391

[An experimental study on ischemically induced brain damage by whole body calorimetry and pathohistology in the gerbil].  

PubMed

Moderate hypothermia has been reported to mitigate neuronal damage in the gerbil brain following brief periods of forebrain ischemia, but the relationship between brain damage and whole body calorimetry has not been clarified. We report the effect of hypothermia on the brain damage by whole body calorimetry using Bio Dynamic Calorimeter (BDC200, ESCO Ltd JAPAN). Although it is an indirect method, whole body calorimetry may be able to measure the brain damage, thereby enabling investigations on alleviation of brain damage. PMID:9621663

Kishi, H

1998-05-01

392

Influence of the emissivity of the sample on differential scanning calorimetry measurements  

Microsoft Academic Search

A possible cause of the wide differences present in the literature values for the calorimetric measurements of the pyrolysis heat of biomass was analyzed. The apparent specific heat of char from pyrolysis of beech wood was investigated by means of a differential scanning calorimeter (DSC). The objective was to find out the influence of the use of a lid on

M. G Wolfinger; J Rath; G Krammer; F Barontini; V Cozzani

2001-01-01

393

Use of differential scanning calorimetry for structural analysis of fungally degraded wood.  

PubMed

This paper assesses the potential use of differential scanning calorimetry for analyzing sound and decayed wood. With sound wood, this method permitted the detection of cellulose, hemicellulose, and lignin components as discrete peaks of combustion at defined temperatures. Characteristic changes in the calorimetric thermogram of birchwood (temperature of maxima, peak height, and peak area) were obtained from wood samples degraded by the basidiomycetes Fomes fomentarius and Piptoporus betulinus. Additional peaks in the thermograms of white rotted birchwood were assigned to lignin degradation products and to mycelium. Results obtained by the differential scanning calorimetry method are compared with those of chemical determination, with particular emphasis on Klason lignin. PMID:16347209

Reh, U; Kraepelin, G; Lamprecht, I

1986-11-01

394

Use of Differential Scanning Calorimetry for Structural Analysis of Fungally Degraded Wood  

PubMed Central

This paper assesses the potential use of differential scanning calorimetry for analyzing sound and decayed wood. With sound wood, this method permitted the detection of cellulose, hemicellulose, and lignin components as discrete peaks of combustion at defined temperatures. Characteristic changes in the calorimetric thermogram of birchwood (temperature of maxima, peak height, and peak area) were obtained from wood samples degraded by the basidiomycetes Fomes fomentarius and Piptoporus betulinus. Additional peaks in the thermograms of white rotted birchwood were assigned to lignin degradation products and to mycelium. Results obtained by the differential scanning calorimetry method are compared with those of chemical determination, with particular emphasis on Klason lignin.

Reh, Ursula; Kraepelin, Gunda; Lamprecht, Ingolf

1986-01-01

395

Thermodynamics of Surfactants, Block Copolymers and Their Mixtures in Water: The Role of the Isothermal Calorimetry  

PubMed Central

The thermodynamics of conventional surfactants, block copolymers and their mixtures in water was described to the light of the enthalpy function. The two methodologies, i.e. the van’t Hoff approach and the isothermal calorimetry, used to determine the enthalpy of micellization of pure surfactants and block copolymers were described. The van’t Hoff method was critically discussed. The aqueous copolymer+surfactant mixtures were analyzed by means of the isothermal titration calorimetry and the enthalpy of transfer of the copolymer from the water to the aqueous surfactant solutions. Thermodynamic models were presented to show the procedure to extract straightforward molecular insights from the bulk properties.

De Lisi, Rosario; Milioto, Stefania; Muratore, Nicola

2009-01-01

396

Calorimetry and thermodynamic aspects of heterotrophic, mixotrophic, and phototrophic growth  

Microsoft Academic Search

A simple stoichiometric model is proposed linking the biomass yield to the enthalpy and Gibbs energy changes in chemo-heterotrophic,\\u000a mixotrophic, and photo-autotrophic microbial growth. A comparison with calorimetric experiments on the algae Chlorella vulgaris and Chlorella sorokiniana confirmed the trends but revealed large calorimetric measurement inaccuracies. The calorimetric data on purely photo-autotrophic\\u000a growth was, however, in fair agreement with calculations.

Urs von StockarIan; Ian Marison; Marcel Janssen; Rodrigo Patiño

2011-01-01

397

Thermal properties and mixing state of diol-water mixtures studied by calorimetry, large-angle X-ray scattering, and NMR relaxation.  

PubMed

Differential scanning calorimetry (DSC) has been performed on aqueous mixtures of three diols, which involve a linear carbon chain, HO-(CH 2) n -OH ( n = 3, 4, and 5), over the whole mole fraction range of diols. The DSC results have shown the alkyl chain parity for the freezing process of the aqueous mixtures: aqueous mixtures of 1,3-propanediol (PrD) and 1,5-pentanediol (PeD) are kept in the supercooled state or vitrified over a wide mole fraction range, while those of 1,4-butanediol (BuD) are easily crystallized. The structure of PrD-water mixtures has been elucidated by using the large-angle X-ray scattering (LAXS) technique. It has been suggested that the structural change of PrD-water mixtures occurs at PrD mole fractions of x PrD = 0.4 and 0.8: in the range of x PrD < or = 0.4 where the tetrahedral-like structure of water predominates, in the range of 0.4 < x PrD < 0.8 where both PrD and water structures coexist, and in the range of x PrD > or = 0.8 where the inherent structure of PrD is mainly formed. (17)O and (1)H NMR relaxation measurements have been made on aqueous mixtures of ethylene glycol (EG, n = 2), PrD, and BuD to clarify the dynamics of H 2 (17)O and diol molecules. The (17)O NMR relaxation rates have suggested that the rotational motion of water molecules is gradually retarded in the diol-water mixtures with increasing diol content and that the restriction of the motion is more remarkable in the order of EG < PrD < BuD. On the basis of all the results, together with comparison with those of methanol-water, ethanol-water, and 1-propanol-water mixtures previously reported, the mixing state of diol-water mixtures has been discussed at the molecular level. PMID:18826183

Takamuku, Toshiyuki; Tsutsumi, Youichi; Matsugami, Masaru; Yamaguchi, Toshio

2008-10-23

398

Thermal behavior of native and hydrophobized wheat gluten, gliadin and glutenin-rich fractions by modulated DSC  

Microsoft Academic Search

The glass transition temperature (Tg) of hydrophobized and native wheat gluten and its protein fractions, with water mass fraction from 0 to 0.2, was studied using modulated differential scanning calorimetry. The Tg values of unplasticized products were ?175°C whatever the treatment (hydrophobization) or the fraction tested, except for the gliadin-rich fraction (162°C). Experimental change in heat capacity at the glass

Valérie Micard; Stéphane Guilbert

2000-01-01

399

DSC and Raman studies of the side chain length effect of ubiquinones on the thermotropic phase behavior of liposomes  

Microsoft Academic Search

Differential scanning calorimetry and Raman spectroscopy have been used to examine the effects of ubiquinones (UQn) on the thermotropic phase behavior of dipalmitoylphosphatidylcholine (DPPC) in multilamellar vesicles, for UQ\\/DPPC molar ratios ranging from 0.01 to 0.1. The influence of the side chain length has been investigated by comparing the effect of a series of UQ with 2 (UQ2), 4 (UQ4),

Yann Roche; Pierre Peretti; Sophie Bernard

2006-01-01

400

Student Learning of Thermochemical Concepts in the Context of Solution Calorimetry.  

ERIC Educational Resources Information Center

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…

Greenbowe, Thomas J.; Meltzer, David E.

2003-01-01

401

Protein Unfolding Coupled to Ligand Binding: Differential Scanning Calorimetry Simulation Approach  

ERIC Educational Resources Information Center

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.

Celej, Maria Soledad; Fidelio, Gerardo Daniel; Dassie, Sergio Alberto

2005-01-01

402

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

SciTech Connect

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.

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

403

Differential scanning calorimetry study of the reactivity of carbon anodes in plastic Li-ion batteries  

Microsoft Academic Search

Chemical reactions taking place at elevated temperatures in a polymer-bonded lithiated carbon anode were studied by differential scanning calorimetry. The influences of parameters such as degree of intercalation, number of cycles, specific surface area, and chemical nature of the binder were elucidated. It was clearly established that the first reaction taking place at ca. 120--140 C was the transformation of

A. du Pasquier; F. Disma; J. M. Tarascon; T. Bowmer; A. S. Gozdz; G. Amatucci

1998-01-01

404

Investigation of biomass pyrolysis by thermogravimetric analysis and differential scanning calorimetry  

Microsoft Academic Search

The influence of sample size on the pyrolysis of wheat straw and three types of cellulose has been investigated by simultaneous thermogravimetric analysis and differential scanning calorimetry. Samples between 2 and 20 mg were pyrolyzed to a maximum temperature of 600°C at a heating rate of 40°C min?1. It was found that sample size had a large effect on the

Mette Stenseng; Anker Jensen; Kim Dam-Johansen

2001-01-01

405

Active metabolic weight estimation using bioimpedance, indirect calorimetry and the clino-ortho maneuver  

Microsoft Academic Search

The resting energy expenditure (REE) and substrate utilization are computed by indirect calorimetry technique (ICT). The REE represents 80-85% of the total energy expenditure (TEE) but only accounts for the 7% of the actual body weight (ABW). The TEE is produced by the organs plus muscles, whereas the REE accounts only for the main organs. An important problem comes up

Miguel Cadena; Joaquín Azpiroz; Gisella Borja; Humberto Medel; Héctor Sandoval; F. Rodriguez; F. Flores; P. Flores

2010-01-01

406

HEAT OF HYDRATION OF SALTSTONE MIXES-MEASUREMENT BY ISOTHERMAL CALORIMETRY  

Microsoft Academic Search

This report provides initial results on the measurement of heat of hydration of Saltstone mixes using isothermal calorimetry. The results were obtained using a recently purchased TAM Air Model 3116 Isothermal Conduction Calorimeter. Heat of hydration is an important property of Saltstone mixes. Greater amounts of heat will increase the temperature of the curing mix in the vaults and limit

J. R. Harbour; V Vickie Williams; T Tommy Edwards

2007-01-01

407

Monolithic junction field-effect transistor charge preamplifier for calorimetry at high luminosity hadron colliders  

SciTech Connect

The outstanding noise and radiation hardness characteristics of epitaxial-channel junction field-effect transistors (JFET) suggest that a monolithic preamplifier based upon them may be able to meet the strict specifications for calorimetry at high luminosity colliders. Results obtained so far with a buried layer planar technology, among them an entire monolithic charge-sensitive preamplifier, are described.

Radeka, V.; Rescia, S. (Brookhaven National Lab., Upton, NY (United States)); Rehn, L.A. (InterFET Corp., Garland, TX (United States)); Manfredi, P.F.; Speziali, V. (Pavia Univ. (Italy). Dipt. di Elettronica Istituto Nazionale di Fisica Nucleare, Milan (Italy))

1991-11-01

408

Monolithic junction field-effect transistor charge preamplifier for calorimetry at high luminosity hadron colliders  

SciTech Connect

The outstanding noise and radiation hardness characteristics of epitaxial-channel junction field-effect transistors (JFET) suggest that a monolithic preamplifier based upon them may be able to meet the strict specifications for calorimetry at high luminosity colliders. Results obtained so far with a buried layer planar technology, among them an entire monolithic charge-sensitive preamplifier, are described.

Radeka, V.; Rescia, S. (Brookhaven National Lab., Upton, NY (United States)); Rehn, L.A. (Interfet Corp., Garland, TX (United States)); Manfredi, P.F.; Speziali, V. (Univ. di Pavia, (Italy). Dipt. di Elettronica INFN, Milano (Italy))

1993-10-01

409

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

Microsoft Academic Search

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

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

2002-01-01

410

Insights into early hydration of Portland limestone cement from infrared spectroscopy and isothermal calorimetry  

Microsoft Academic Search

Isothermal calorimetry and diffuse reflectance infrared DR–FTIR spectroscopy are combined to correlate evolutions of spectroscopic signatures with rates of chemical reactions as reflected in the rate of heat emitted during the first 38h of cement hydration. Portland limestone cement mortar is employed and the analysis is repeated for two different mixing procedures. Intensive blender mixing with quartz sand is found

Rikard Ylmén; Lars Wadsö; Itai Panas

2010-01-01

411

Resonant acoustic calorimetry of the interaction of laser radiation with nonlinear-optical crystals  

Microsoft Academic Search

Resonant acoustic calorimetry technique gives the opportunity to measure the crystal temperature during linear and nonlinear interaction of the laser radiation with crystals. It is based on the registration of the piezoelectric resonance frequency change caused by the interaction of the laser radiation with crystals. Piezoelectric resonance is observed by measuring the dependence of the sample electrical impedance on the

A. V. Konyashkin; A. V. Doronkin; V. A. Tyrtyshnyy; D. V. Myasnikov; O. A. Ryabushkin

2009-01-01

412

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

NASA Technical Reports Server (NTRS)

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.

Ebner, W. B.

1982-01-01

413

Energy Storage Capacity of Reversible Liquid Phase Diels-Alder Reactions as Determined by Drop Calorimetry.  

National Technical Information Service (NTIS)

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 f...

C. P. Chung

1983-01-01

414

Determination of calorific values of forest waste biomass by static bomb calorimetry  

Microsoft Academic Search

Calorific values of forest waste originating from forestry works such as woodland cleaning, reaforestation and, all other silviculture tasks, were measured by static bomb calorimetry. These waste materials, heretofore considered as useless refuse, are beginning to be used as alternative fuels in wide social sectors all over the world. Two of the main forest species, eucalyptus (E. globulus Labill) and

Lisardo Núñez-Regueira; Jose A. Rodr??guez-Añon; Jorge Proup??n-Castiñeiras; A. Vilanova-Diz; N. Montero-Santoveña

2001-01-01

415

REVIEW ARTICLE: Investigating the thermodynamics and kinetics of thin film reactions by differential scanning calorimetry  

Microsoft Academic Search

In this paper we demonstrate the utility of differential scanning calorimetry for investigating the thermodynamics and kinetics of a broad range of thin film reactions. We begin by describing differential scanning calorimeters and the preparation of thin film samples. We then cite a number of examples that illustrate how enthalpies of crystallization, heats of formation and enthalpies of interfaces can

C. Michaelsen; K. Barmak; T. P. Weihs

1997-01-01

416

Calorimetry exchange program quarterly data report for, January 1989--March 1989  

SciTech Connect

The goals of the calorimetry sample exchange program are to: discuss measurement differences; improve analytical methods; discuss new measurement capabilities; provide data to DOE on measurement capabilities to evaluate shipper-receiver differences; provide standardized materials as necessary; and provide a measurement control program for plutonium analysis. A sample of plutonium dioxide powder is available at each participating site for NDA analysis.

Lyons, J.E.; McClelland, T.M.

1996-08-01

417

Levitation calorimetry. IV - The thermodynamic properties of liquid cobalt and palladium.  

NASA Technical Reports Server (NTRS)

Some of the thermodynamic properties of liquid cobalt and palladium investigated by means of levitation calorimetry are reported and discussed. The presented data include the specific heats and heats of fusion of the liquid metals, and the emissivities of the liquid metal surfaces.

Treverton, J. A.; Margrave, J. L.

1971-01-01

418

Structure and Phase Transitions of Poly (Hexamethylene p,p'-Bibenzoate) as Studied by DSC and Real-Time SAXS/WAXS Employing Synchrotron Radiation  

SciTech Connect

Real-time small and wide angle X-ray scattering as well as DSC studies were carried out in order to analyzes the structure and phase transitions of liquid crystalline thermotropic poly(methylene p,p' bibenzoat)

Katerska, B.; Krasteva, M. [University of Sofia, Faculty of Physics, blvd James Bourchier 5, 1164 Sofia (Bulgaria); Perez, E. [Instituto de Sciencia y Technolodia de Polimeros (CSIC) Juan de la Ciera 3, 28006 Madrid (Spain)

2007-04-23

419

Mathematical analysis for radiometric calorimetry of a radiating sphere  

NASA Technical Reports Server (NTRS)

Equations are derived from which the temperature dependence of both the specific heat and the thermal diffusivity of a spherical sample of material can be calculated from observations of the time dependence of the surface temperature and the time-rate of energy loss from the sample as it cools. The derivation takes into account the nonuniformity of the interior temperature field of the sample, and the resulting equations can be applied not only to radiative cooling, but also to any other cooling mechanism that does not violate the assumed spherical symmetry. The analysis excludes change of phase, but it does take thermal expansion into account. To permit the making of estimates necessary for the design of radiative cooling experiments, a universal temperature-time cooling curve is derived for the post-transient cooling regime of a radiating sphere of any size with arbitrary, but constant, thermal parameters.

Schmid, L. A.

1982-01-01

420

Molecular Characterization and Alternative Splicing of a Sodium Channel and DSC1 Ortholog Genes in Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae)  

PubMed Central

Alternative splicing greatly contributes to the structural and functional diversity of voltage-gated sodium channels (VGSCs) by generating various isoforms with unique functional and pharmacological properties. Here, we identified a new optional exon 23 located in the linker between domains II and III, and four mutually exclusive exons (exons 27A, 27B, 27C, and 27D) in domains IIIS3 and IIIS4 of the sodium channel of Liposcelis bostrychophila (termed as LbVGSC). This suggested that more alternative splicing phenomena remained to be discovered in VGSCs. Inclusion of exon 27C might lead to generation of non-functional isoforms. Meanwhile, identification of three alternative exons (exons 11, 13A, and 13B), which were located in the linker between domains II and III, indicated that abundant splicing events occurred in the DSC1 ortholog channel of L. bostrychophila (termed as LbSC1). Exons 13A and 13B were generated by intron retention, and the presence of exon 13B relied on the inclusion of exon 13A. Exon 13B was specifically expressed in the embryonic stage and contained an in-frame stop codon, inclusion of which led to generation of truncated proteins with only the first two domains. Additionally, several co-occurring RNA editing events were identified in LbSC1. Furthermore, remarkable similarity between the structure and expression patterns of LbVGSC and LbSC1 were discovered, and a closer evolutionary relationship between VGSCs and DSC1 orthologs was verified. Taken together, the data provided abundant molecular information on VGSC and DSC1 orthologs in L. bostrychophila, a representative Psocoptera storage pest, and insights into the alternative splicing of these two channels.

Jiang, Xuan-Zhao; Wei, Dan-Dan; Yang, Wen-Jia; Dou, Wei; Chen, Shi-Chun; Wang, Jin-Jun

2013-01-01

421

Experimental measurements of the heats of formation of Fe{sub 3}Pt, FePt, and FePt{sub 3} using differential scanning calorimetry  

SciTech Connect

Using differential scanning calorimetry (DSC), the heats of formation of Fe{sub 3}Pt, FePt, and FePt{sub 3} were determined from the reaction of sputter deposited Fe/Pt multilayer thin-films with a periodicity of 200 nm but different overall compositions. Film compositions were measured by energy dispersive x-ray spectrometry. The phases present along the reaction path were identified by x-ray diffraction. For the most Fe-rich phase, namely, Fe{sub 3}Pt, the measured enthalpy of formation was -9.3 {+-} 1.3 kJ/mol in a film with a composition of 70.4:29.6 ({+-}0.2 at. %) Fe:Pt. For FePt, the measured enthalpy of formation was -27.2 {+-} 2.2 kJ/g-atom in a 49.0:51.0 ({+-}0.5 at. %) Fe:Pt film. For FePt{sub 3}, which is the most Pt rich intermetallic phase, the measured enthalpy of formation was -23.7 {+-} 2.2 in a film with a composition of 22.2:77.8 ({+-}0.6 at. %) Fe:Pt. The reaction enthalpies for films with Fe:Pt compositions of 44.5:55.5 ({+-}0.3 at. %) and 38.5:61.5 ({+-}0.4 at. %) were -26.9 {+-} 1.0 and -26.6 {+-} 0.6 kJ/g-atom, respectively, which taken together with the value for the 49.0:51.0 film demonstrate the relative insensitivity of the reaction enthalpy to film composition over a broad composition range in the vicinity of the equiatomic composition. The experimental heats of formation are compared with two sets of reported first-principles calculated values for each of the three phases at exact stoichiometry.

Wang, B.; Berry, D. C.; Chiari, Y.; Barmak, K. [Department of Materials Science and Engineering and the Data Storage Systems Center, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, Pennsylvania 15213 (United States)

2011-07-01

422

Application of a simultaneous TGA-DSC thermal analysis system for high-throughput screening of catalytic activity.  

PubMed

We present here the use of a simultaneous TGA/DSC thermal analyzer as a high-throughput reactor system to measure after calibration the heat of reaction and therefore the catalytic activity of heterogeneous catalysts in a fast, reliable and reproducible manner. By coupling the gas outlet of the analyzer with a mass spectrometer via a heated capillary additional data can be acquired. As a test reaction the oxidation of carbon monoxide with synthetic air, using Hopcalite and several transition and noble metals as catalysts, was chosen. The setup presented allows the rapid sequential screening of about 70 catalysts per day. PMID:23113621

Loskyll, Jonas; Maier, Wilhelm F; Stoewe, Klaus

2012-11-12

423

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

NASA Technical Reports Server (NTRS)

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

Wingard, Doug

2010-01-01

424

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

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 50wt% 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

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

2014-05-15

425

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

PubMed

The study highlighted the main forces driving the formation of hydroxypropyl-cyclodextrins (HP-CDs) + poly(propylene) glycol 725 g mol(-1) inclusion complexes. The temperature parameter was chosen as the variable to modulate the hydrophobicity of the polymer, and consequently ITC experiments as functions of temperature as well as DSC measurements were done in a systematic way. The polymer is not included into HP-?-CD, it is strongly bound to HP-?-CD and it is floating in HP-?-CD. The stability of the inclusion complexes is entropy controlled. The gain of the entropy is a unique result compared to the opposite literature findings for inclusion complexes based on polymers and CDs. This peculiarity is ascribable to the removal of water molecules from cages during complexation and this effect compensates the entropy loss due to constraints caused by the CD threading. In spite the host-guest van der Waals contacts are optimized, the enthalpies for the inclusion complex formation are positive and reveal the large heat required for dehydrating the propylene oxide units. All the macrocycles enhanced the polymer solubility in water. Increasing the affinity of the macrocycle to the macromolecule makes more expanded the one-phase area of the binodal curve. A new thermodynamic approach was proposed to predict quantitatively the binodal curve as well as the dependence of the enthalpy of separation phase on the macrocycle composition. The agreement between the experimental data and the computed values was excellent. PMID:21666930

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

2011-07-21

426

A study of the freezing of supercooled water dispersed within emulsions by differential scanning calorimetry  

Microsoft Academic Search

Supercooling of microsize droplets of water dispersed within emulsions has been studied by means of a differential scanning calorimeter Perkin-Elmer DSC 2. In an emulsion cooled steadily at 2.5K min-1, the breakdown of supercooling in individual droplets is distributed in temperature over the range -37.5 degrees C to -40.5 degrees C, the most probable temperature of freezing being T*=-(39.0+or-0.5) degrees

F. Broto; D. Clausse

1976-01-01

427

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

NASA Astrophysics Data System (ADS)

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

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

2001-03-01

428

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

PubMed

The systematic investigation of susceptibility-induced contrast in MRI is important to better interpret the influence of microvascular and microcellular morphology on DSC-MRI derived perfusion data. Recently, a novel computational approach called the Finite Perturber Method (FPM), which enables the study of susceptibility-induced contrast in MRI arising from arbitrary microvascular morphologies in 3D has been developed. However, the FPM has lower efficiency in simulating water diffusion especially for complex tissues. In this work, an improved computational approach that combines the FPM with a matrix-based finite difference method (FDM), which we call the Finite Perturber the Finite Difference Method (FPFDM), has been developed in order to efficiently investigate the influence of vascular and extravascular morphological features on susceptibility-induced transverse relaxation. The current work provides a framework for better interpreting how DSC-MRI data depend on various phenomena, including contrast agent leakage in cancerous tissues and water diffusion rates. In addition, we illustrate using simulated and micro-CT extracted tissue structures the improved FPFDM along with its potential applications and limitations. PMID:24416281

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

2014-01-01

429

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

PubMed

The influence of temperature on the adsorption of PEGylated lysozyme and pure PEG on Toyopearl PPG-600M, a hydrophobic resin, is studied by batch equilibrium measurements and pulse response experiments. Differently PEGylated lysozymes are used for the studies, enabling a systematic variation of the solute properties. Either ammonium sulfate or sodium chloride are added. The enthalpy of adsorption is calculated from a van't Hoff analysis based on these data. It is also directly measured by Isothermal Titration Calorimetry. In the investigated temperature range from 5°C to 35°C adsorption is favored by higher temperatures and hence endothermic. The results of the van't Hoff analysis of the equilibrium and the pulse response data agree well. Discrepancies between enthalpies of adsorption obtained by calorimetry and van't Hoff analysis are found and discussed. We conclude that the most likely explanation is that thermodynamic equilibrium is not reached in the experiments even though they were carried out carefully and in the generally accepted way. PMID:25016322

Werner, Albert; Hackemann, Eva; Hasse, Hans

2014-08-22

430

Student learning of thermochemical concepts in the context of solution calorimetry  

NSDL National Science Digital Library

Student understanding of heat and thermal phenomena has been the subject of considerable investigation in the science education literature. Published studies have reported student conceptions on a variety of advanced topics, but calorimetry - one of the more elementary applications of thermochemical concepts - has apparently received little attention from science education researchers. Here we report a detailed analysis of student performance on solution calorimetry problems in an introductory university chemistry class. We include data both from written classroom exams for 207 students, and from an extensive longitudinal interview series with a single subject who was herself part of that larger class. Our findings reveal a number of learning difficulties, most of which appear to originate from failure to understand that net increases and decreases in bond energies during aqueous chemical reactions result in energy transfers out of and into, respectively, the total mass of the resultant solution.

Greenbowe, Thomas

2005-10-06

431

Studying RNA-RNA and RNA-Protein Interactions by Isothermal Titration Calorimetry  

PubMed Central

Isothermal Titration Calorimetry (ITC) provides a sensitive and accurate means by which to study the thermodynamics of RNA folding, RNA binding to small molecules, and RNA–protein interactions. The advent of extremely sensitive instrumentation and the increasing availability of ITC in shared facilities have made it increasingly valuable as a tool for RNA biochemistry. As an isothermal measurement, it allows analysis at a defined temperature, distinguishing it from thermal melting approaches (UV melting and differential scanning calorimetry, for instance) that provide thermodynamic information specific to the melting temperature. Residual structures at low temperature in the unfolded state and heat capacity changes lead to potential differences between thermodynamic values measured by ITC and those derived from melting studies. This article describes how ITC can be put to use in the study of RNA biochemistry.

Feig, Andrew L.

2011-01-01

432

Effects of lipid membrane curvature on lipid packing state evaluated by isothermal titration calorimetry.  

PubMed

In this report, we present a novel approach for the elucidation of the physicochemical properties of lipid membranes by isothermal titration calorimetry (ITC) to quantify the heat absorbed during the solubilization of vesicles into TritonX-100 micelles. By using large and small unilamellar vesicles for comparison, this method provides calorimetric data on the gel-to-liquid-crystalline phase transition and its curvature effects and, in particular, the enthalpy change upon membrane deformation from a planar to a curved shape, which cannot be obtained by the conventional approach using differential scanning calorimetry. The results showed quantitatively that the increase in membrane curvature increases the enthalpy of 1,2-dimyristoyl-sn-glycero-3-phosphocholine membranes both below and above the phase-transition temperature, and that the effect is more significant for the former condition. The calorimetric data obtained are further discussed in relation to the elastic bending energy of the membranes and membrane-peptide interaction. PMID:23270307

Yokoyama, Hirokazu; Ikeda, Keisuke; Wakabayashi, Masaki; Ishihama, Yasushi; Nakano, Minoru

2013-01-22

433

Application of isothermal calorimetry and uv spectroscopy for stability monitoring of pentaerythritol tetranitrate  

SciTech Connect

Thermal stabilities for a series of pentaerythritol-tetranitrate (PETN) samples with variable surf ace areas were monitored by isothermal calorimetry and UV spectroscopy over the temperature range of 363 to 408 K. Isothermal induction times measured with constant volume calorimetry under an air atmosphere and No evolution rates monitored by UV absorbance at 213 nm under vacuum correlated with the PETN surface area at temperatures equal to or exceeding 383 K. Rate data measured at 383 K are in accord with predictions based on detailed kinetic modeling. Below 383 K, NO evolution data suggested that additional geometric factors may be significant in controlling PETN stability. Mechanisms for influencing surface area upon the rate-determining step are addressed.

Dosser, L.R.; Pickard, J.M.

1992-01-01

434

Thermal Analysis of Plastics  

ERIC Educational Resources Information Center

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

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

2008-01-01

435

Polymorphism and transformation energetics of saturated monoacid triglycerides from differential scanning calorimetry and theoretical modeling  

Microsoft Academic Search

Differential scanning calorimetry studies on saturated monoacid triglycerides were extended to include most odd and even chain\\u000a lengths from tricaprylin (C8) through tritriacontanoin (C30). Two ?’-forms were common with triglycerides C15 through C24: shorter odd chain length triglycerides (C9-C13) exhibited only one ?’-form; short even chain length triglycerides (C8-C14) exhibited three. Odd chain length C21 and C23 triglycerides showed two

J. W. Hagemann; J. A. Rothfus

1983-01-01

436

Differential scanning calorimetry of single acid triglycerides: Effect of chain length and unsaturation  

Microsoft Academic Search

The polymorphism of 13 single acid triglycerides with acyl group chain lengths ranging from 16–22 was studied by differential\\u000a scanning calorimetry. In contrast to the single??-form generally attributed to such triglycerides, at least two intermediate endotherms were found for most samples between\\u000a the least stable (?) and most stable (?) polymorphs. For saturated triglycerides, two versions of the familiar “tuning

J. W. Hagemann; W. H. Tallent; K. E. Kolb

1972-01-01

437

Investigation of Phase Transitions of Lipids and Lipid Mixtures by High Sensitivity Differential Scanning Calorimetry  

Microsoft Academic Search

High sensitivity differential scanning calorimetry is applied to the study of the thermotropic behavior of mixtures of synthetic phospholipids in multilamellar aqueous suspensions. The systems dimyristoylphosphatidylcholine-dipalmitoylphosphatidylcholine, dimyristoylphosphatidylcholine-distearoylphosphatidylcholine, and dimyristoylphosphatidylethanolamine-distearoylphosphatidylcholine, although definitely nonideal, exhibit essentially complete miscibility in both gel and liquid crystalline states, while the system dilauroylphosphatidylcholine-distearoylphosphatidylcholine is monotectic with lateral phase separation in the gel state. Comparison of the

Susan Mabrey; Julian M. Sturtevant

1976-01-01

438

Highly sensitive thermopile heat power sensor for micro-fluid calorimetry of biochemical processes  

Microsoft Academic Search

A micro-fluid chip calorimeter measuring system with highly stable thermostat (0.1mK) was developed based on an improved nano calorimetry thin-film thermopile chip with excellent chemical and mechanical reliability fabricated in SU-8 technology for insulation and passivation layers. Biochemical processes (e.g. enzyme catalyzed reaction) can be investigated with heat power detection limit <100nW.

V. Baier; R. Födisch; A. Ihring; E. Kessler; J. Lerchner; G. Wolf; J. M. Köhler; M. Nietzsch; M. Krügel

2005-01-01

439

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

Microsoft Academic Search

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

Martin Fleischmann; Stanley Pons

1993-01-01

440

The role of calorimetry in chemical plant safety: a chlorination reaction  

Microsoft Academic Search

The use of isoperibolic (near-isothermal) and adiabatic reaction calorimetry is discussed with particular reference to a chlorination reaction. The reaction, involving the semi-batch addition of a liquid substrate to a chlorine-saturated solution of dichloromethane containing a catalytic quantity of pyridine, was simulated under isoperibolic conditions (to assess the heat of reaction and extent of reagent accumulation at the proposed reaction

Stephen M. Rowe

1996-01-01

441

Heat capacity of the AuZr compound obtained by high-temperature drop calorimetry  

Microsoft Academic Search

The enthalpy increments of the Zr0.50Au0.50 phase have been measured by high-temperature drop calorimetry in the temperature range 372–1245 K. From these results, heat capacities of ZrAu have been derived and two changes of the Cp values have been observed, in agreement with the existence of three crystalline forms of ZrAu. No latent heat was observed for the low-temperature (564 K) transition,

M. Lomello-Tafin; M. Y. Benarchid; C. Antion; A. Janghorban; J. M. Moreau

2011-01-01

442

Phase transition kinetics of lipid bilayer membranes studied by time-resolved pressure perturbation calorimetry  

Microsoft Academic Search

The relaxation kinetics of aqueous lipid dispersions after a pressure jump (p-jump) was investigated using time-resolved pressure\\u000a perturbation calorimetry (PPC). Analysis of the calorimetric response curves by deconvolution with the instrumental response\\u000a function gives information about slow processes connected with the lipid phase transition. The lipid transition from the gel\\u000a to the liquid-crystalline state was found to be a multi-step

Martin Schiewek; Alfred Blume

2010-01-01

443

Phase behaviour of Maya crude oil based on calorimetry and rheometry  

Microsoft Academic Search

The phase behaviour of Maya crude oil and its nano-filtered sub fractions was studied using differential scanning calorimetry and phase angle measurements in the temperature range 173–573K at atmospheric pressure. The combination of these two te