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1

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

2

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

3

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

4

Comparative Study Of Various Grades Of Polyethylene By Differential Scanning Calorimetry (DSC) Correlated With Raman Spectroscopy  

NASA Astrophysics Data System (ADS)

Polyethylene (PE) is a very important material. In 2008, almost 30% of the world plastics production was dedicated to this polymer (70 million tons) [1]. It is a consumer polymer because of its moderate cost of manufacturing and its physical and mechanical properties compatible with various applications in everyday life. Indeed, PE is generally easily processable. It possesses an excellent electric insulation and shock resistance combined with a very good chemical and biological inertia [2]. For each application, there is a particular grade, i.e. a polyethylene with well defined rheological properties. Therefore, it is essential to know how to differentiate these different grades by suitable methods of characterization. Differential Scanning Calorimetry (DSC) is one of the techniques usually used for this purpose. The knowledge of characteristic temperatures such as melting, cold crystallization or glass transition gives information on the viscosity and thus, on the grade of the polymer. DSC also allows the detection of defects, (for example, presence of unmelted pieces). However DSC is a tedious method for on-line quality control, limiting its scope. The determination of the polymer structure represents a major challenge in the industrial world of polymers. Raman spectroscopy, another technique of polymer analysis, is nowadays growing fast because of the advantages it presents. It is a non-destructive method, capable of also giving useful information about the morphology of the polymer. This technique can be perfectly used in industry by means of adapted sensors and devices with more and more reduced dimensions [3]. That technique is used to obtain the characteristic temperatures of PE and information on the polymer structure. The purpose of this article is to establish the correlation between the viscosity of a polymer and its characteristic temperatures obtained by DSC and subsequent possibilities of quality control in industry. These measurements are correlated with others obtained by Raman spectroscopy, to get additional details concerning the structure and transitions of the material, the final goal being to use these results in on-line analysis.

Jumeau, Richard; Bourson, Patrice; Ferriol, Michel; Lahure, François; Ducos, Franck; Ligneron, Jérôme

2011-05-01

5

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

6

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.

David N. Blauch

7

Kinetics of Cold-Cap Reactions for Vitrification of Nuclear Waste Glass Based on Simultaneous Differential Scanning Calorimetry - Thermogravimetry (DSC-TGA) and Evolved Gas Analysis (EGA)  

SciTech Connect

For vitrifying nuclear waste glass, the feed, a mixture of waste with glass-forming and modifying additives, is charged onto the cold cap that covers 90-100% of the melt surface. The cold cap consists of a layer of reacting molten glass floating on the surface of the melt in an all-electric, continuous glass melter. As the feed moves through the cold cap, it undergoes chemical reactions and phase transitions through which it is converted to molten glass that moves from the cold cap into the melt pool. The process involves a series of reactions that generate multiple gases and subsequent mass loss and foaming significantly influence the mass and heat transfers. The rate of glass melting, which is greatly influenced by mass and heat transfers, affects the vitrification process and the efficiency of the immobilization of nuclear waste. We studied the cold-cap reactions of a representative waste glass feed using both the simultaneous differential scanning calorimetry thermogravimetry (DSC-TGA) and the thermogravimetry coupled with gas chromatography-mass spectrometer (TGA-GC-MS) as complementary tools to perform evolved gas analysis (EGA). Analyses from DSC-TGA and EGA on the cold-cap reactions provide a key element for the development of an advanced cold-cap model. It also helps to formulate melter feeds for higher production rate.

Rodriguez, Carmen P. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); ; Pierce, David A. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); ; Schweiger, Michael J. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); ; Kruger, Albert A. [USDOE Office of River Protection, Richland, WA (United States); Chun, Jaehun [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); ; Hrma, Pavel R. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States);

2013-12-03

8

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. PMID:21119929

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

2010-01-01

9

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

SciTech Connect

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

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

2012-07-01

10

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

11

Use of differential scanning calorimetry (DSC) as a new technique for detection of adulteration in honeys. 1. Study of adulteration effect on honey thermal behavior.  

PubMed

Differential scanning calorimetry (DSC) was used to study the thermal behavior of authentic honeys (Lavandula, Robinia, and Fir honeys) and industrial sugar syrups. Thermal or thermochemical parameters such as the glass transition temperature (Tg), enthalpies of fusion (DeltaH(fus)), and heat capacity variation (DeltaC(p)) were measured. The syrups and honeys showed significant differences in thermal phenomena, as well as in their amplitude and position on the temperature scale. Results showed good reproducibility of the method for all samples studied. The effect of adulteration of honey with different amounts of syrup (5, 10, 20, 40, and 60%) was investigated. A linear relationship was found between the percentage of added syrup and the glass transition temperature. A similar relationship was obtained from the enthalpy of fusion results in the temperature range of 40-90 degrees C. Under applied conditions, the effects of adulteration of honeys by industrial syrups appeared to be detectable from a level as low as 5%. PMID:11754568

Cordella, Christophe; Antinelli, Jean-François; Aurieres, Clément; Faucon, Jean-Paul; Cabrol-Bass, Daniel; Sbirrazzuoli, Nicolas

2002-01-01

12

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

PubMed

Starting from the Debye model for frequency-dependent specific heat and the Vogel-Fulcher-Tammann (VFT) model for its relaxation time, an analytic expression is presented for the heat capacity versus temperature trace for differential scanning calorimetry (DSC) of glass transitions, suggesting a novel definition of the glass transition temperature based on a dimensionless criterion. An explicit expression is presented for the transition temperature as a function of the VFT parameters and the cooling rate, and for the slope as a function of fragility. Also a generalization of the results to non-VFT and non-Debye relaxation is given. Two unique ways are proposed to tackle the inverse problem, i.e., to extract the fragility from an experimental DSC trace. Good agreement is found between theoretically predicted DSC traces and experimental DSC traces for glycerol for different cooling rates. PMID:22299886

Fivez, J; Longuemart, S; Glorieux, C

2012-01-28

13

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

NASA Astrophysics Data System (ADS)

Starting from the Debye model for frequency-dependent specific heat and the Vogel-Fulcher-Tammann (VFT) model for its relaxation time, an analytic expression is presented for the heat capacity versus temperature trace for differential scanning calorimetry (DSC) of glass transitions, suggesting a novel definition of the glass transition temperature based on a dimensionless criterion. An explicit expression is presented for the transition temperature as a function of the VFT parameters and the cooling rate, and for the slope as a function of fragility. Also a generalization of the results to non-VFT and non-Debye relaxation is given. Two unique ways are proposed to tackle the inverse problem, i.e., to extract the fragility from an experimental DSC trace. Good agreement is found between theoretically predicted DSC traces and experimental DSC traces for glycerol for different cooling rates.

Fivez, J.; Longuemart, S.; Glorieux, C.

2012-01-01

14

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

15

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.

16

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

17

Raman scattering and modulated-DSC experiments on Potassium Germanate glasses*  

NASA Astrophysics Data System (ADS)

We have synthesized titled glasses in the 0 < x < 0.16 range by traditional melt-quenching, and have examined them in Raman scattering and modulated-DSC (MDSC) experiments. Raman lineshapes observed in the present work are quite similar to those reported by Henderson and Wang ^1. Preliminary MDSC experiments reveal glass transition temperatures, Tg(x), starting from a value of 570 C at x = 0, to decrease to 508 C near x = 0.06, and to increase thereafter almost linearly to 552 C as x increases to 0.15. On the other hand, the non-reversing enthalpy associated with Tg provides evidence of a global minimum in the 0.08 < x < 0.10 range, the reversibility window^2. These results are consistent with glasses at x < 0.08 as Stressed-Rigid, those at x > 0.10 as Floppy, while those in the reversibility window as representing the Intermediate Phase^2. The space filling nature of the Intermediate Phase is, independently, corroborated by trends in molar volumes which show a broad global minimum in the 9-11% range. Identification of the three elastic phases provides a physical basis to understand the origin of the Germanate anomaly, and the electrical conductivity threshold when glasses become mechanically floppy. *Supported by NSF grant DMR 04-56472. ^1 G.S.Henderson and H.M.Wang, Eur. J. Mineral. 14, 733 (2002). ^2 P.Boolchand, G.Lucovsky, J.C. Phillips and M.F.Thorpe, Phil. Mag 85,3823 (2005).

Wang, N.; Novita, D.; Boolchand, P.

2006-03-01

18

Differential scanning calorimetry characterization of water-in-oil emulsions from Mexican crude oils  

Microsoft Academic Search

A simplified equation relating water droplet size distribution to crystallization temperature, determined from differential\\u000a scanning calorimetry (DSC) curves of aqueous emulsions of petroleum is reported in this article. A series of water-in-oil\\u000a (W\\/O) emulsions was prepared by dispersion of water in different Mexican crude oils; in a classical DSC experiment, these\\u000a emulsions were submitted to a regular heating and cooling

Javier A. Díaz-Ponce; Eugenio A. Flores; Alfonso Lopez-Ortega; Jose G. Hernández-Cortez; Arquimides Estrada; Laura V. Castro; Flavio Vazquez

2010-01-01

19

UV-curable epoxy systems containing hyperbranched polymers: Kinetics investigation by photo-DSC and real-time FT-IR experiments  

Microsoft Academic Search

The effect of the presence of a hyperbranched OH-functionalized polymer (HBP) on the kinetics of cationic photopolymerization of an epoxy system was investigated employing two complementary techniques, photo-DSC and real-time FT-IR spectroscopy.Lower rates of cross-linking reactions and higher conversion degrees were obtained in photo-DSC experiments with respect to real-time FT-IR spectroscopy. A limited amount (10% wt) of HBP influenced to

Carola Esposito Corcione; Giulio Malucelli; Mariaenrica Frigione; Alfonso Maffezzoli

2009-01-01

20

Investigation of catalytic glycolysis of polyethylene terephthalate by differential scanning calorimetry  

Microsoft Academic Search

The glycolysis of polyethylene terephthalate resin with excess amount of ethylene glycol, using metal acetates as catalysts, was examined by differential scanning calorimetry (DSC). The experiments were carried out under a nitrogen atmosphere of 600 psi. The efficiency of glycolysis was measured from the peak temperature associated with reaction endotherm. Among all the catalysts studied zinc acetate was confirmed to

C. Y. Kao; W. H. Cheng; B. Z. Wan

1997-01-01

21

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

PubMed

Isothermal titration calorimetry (ITC) is the gold standard for dissecting the thermodynamics of a biomolecular binding process within a single experiment. However, reliable determination of the dissociation constant (KD) from a single titration is typically limited to the range 100?M>KD>1nM. Interactions characterized by a lower KD can be assessed indirectly by so-called competition or displacement assays, provided that a suitable competitive ligand is available whose KD falls within the directly accessible window. However, this protocol is limited by the fact that it necessitates at least two titrations to characterize one high-affinity inhibitor, resulting in considerable consumption of both sample material and time. Here, we introduce a fast and efficient ITC displacement assay that allows for the simultaneous characterization of both a high-affinity ligand and a moderate-affinity ligand competing for the same binding site on a receptor within a single experiment. The protocol is based on a titration of the high-affinity ligand into a solution containing the moderate-affinity ligand bound to the receptor present in excess. The resulting biphasic binding isotherm enables accurate and precise determination of KD values and binding enthalpies (?H) of both ligands. We discuss the theoretical background underlying the approach, demonstrate its practical application to metal ion chelation, explore its potential and limitations with the aid of simulations and statistical analyses, and elaborate on potential applications to protein-inhibitor interactions. PMID:25461813

Krainer, Georg; Keller, Sandro

2015-04-01

22

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

23

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

24

Thermal unfolding of Escherichia coli trigger factor studied by ultra-sensitive differential scanning calorimetry  

Microsoft Academic Search

Temperature-induced unfolding of Escherichia coli trigger factor (TF) and its domain truncation mutants, NM and MC, were studied by ultra-sensitive differential scanning calorimetry (UC-DSC). Detailed thermodynamic analysis showed that thermal induced unfolding of TF and MC involves population of dimeric intermediates. In contrast, the thermal unfolding of the NM mutant involves population of only monomeric states. Covalent cross-linking experiments confirmed

Dong-Jie Fan; Yan-Wei Ding; Xian-Ming Pan; Jun-Mei Zhou

2008-01-01

25

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

26

TG–DSC analysis applied to contemporary oil paints  

Microsoft Academic Search

Thermogravimetry coupled with differential scanning calorimetry (TG–DSC) has been commonly used in the field of conservation\\u000a of Cultural Heritage for the study of art objects, especially for the characterisation of inorganic matrixes. In recent years,\\u000a thermal analyses have been applied to the study of organic painting materials. The advantages of performing TG–DSC are linked\\u000a to the fact that it is

Francesca Caterina Izzo; Elisabetta Zendri; Guido Biscontin; Eleonora Balliana

2011-01-01

27

DSC characterisation of compression moulded PEEK-PTFE plaques  

Microsoft Academic Search

Compression moulded plaques of a range of poly(ether ether ketone) (PEEK)- poly(tetrafluoroethylene) (PTFE) blends (100, 92,\\u000a 48, 29, 9.5 and 0 mass% PEEK) have been characterised using differential scanning calorimetry (DSC) and wide angle X-ray crystallography\\u000a (WAXD). A shift in the melting peak of the PEEK phase from 347 to 358C was observed with increasing proportion of PTFE in\\u000a the

P. S. Thomas; B. H. Stuart

2003-01-01

28

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, ...

29

Cell asymmetry correction for temperature modulated differential scanning calorimetry  

SciTech Connect

The quality of measurement of heat capacity by differential scanning calorimetry (DSC) is based on strict symmetry of the twin calorimeter, which is important for temperature-modulated DSC. Heat capacities for sapphire-filled and empty aluminium calorimeters (pans) under designed cell imbalance caused by different pan-masses were measured. In addition, positive and negative signs of asymmetry were explored by analyzing the phase-shift between temperature and heat flow for sapphire and empty runs. The phase shifts change by more than 18{degree} depending on asymmetry sign. Once the asymmetry sign is determined, the asymmetry correction for modulated DSC can be made.

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

1996-12-31

30

A system of differential scanning calorimetry for the investigation of medicinal preparations  

Microsoft Academic Search

A new system for differential scanning calorimetry (DSC) is described, which comprises a DSC setup linked via an interface\\u000a to an IBM PC provided with specially developed software. The DSC instrument operation is based on the measurement of a local\\u000a temperature difference with the aid of a disk thermocouple. The new system has been tested by the analysis of model

Yu. V. Moshchenskii; S. V. Fedotov; L. E. Zhnyakina; S. G. Smelova; M. L. Tkachenko

2005-01-01

31

Study of glass transition of metallic glasses by temperature-modulated differential scanning calorimetry (MDSC)  

Microsoft Academic Search

The glass transition behavior of several Zr- and Mg-based metallic glasses has been studied by temperature-modulated differential scanning calorimetry (MDSC). It is clearly demonstrated that the glass transition can be separated from crystallization for these glasses by MDSC. Some glass transitions that could not be observed by a conventional differential scanning calorimetry (DSC) have been detected. Furthermore, the complex change

Z. P Lu; Y Li; S. C Ng; Y. P Feng

2000-01-01

32

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

33

DSC analysis on water state of salvia hydrogels  

Microsoft Academic Search

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

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

2009-01-01

34

Wave shapes in alternating DSC  

Microsoft Academic Search

ADSC with its periodical temperature programs combines the features of DSC measured at high heating rate (high sensitivity)\\u000a with those at low heating rate (high temperature resolution). In addition, the “reversing” cp effects can be separated from the “non-reversing” latent heat effects. Various periodical temperature programs can be applied.\\u000a This paper compares the different possible temperature programs and their algorithms

B. Schenker; G. Widmann; R. Riesen

1997-01-01

35

DSC Determination of Glass Transition Temperature on Sea Bass ( Dicentrarchus labrax ) Muscle: Effect of High-Pressure Processing  

Microsoft Academic Search

Differential scanning calorimetric determination of glass transition temperature in the freeze-concentrated matrix ($$ T_{\\\\text{g}}^{\\\\text{'}} $$) of sea bass muscle was optimized. Conventional and modulated differential scanning calorimetry (DSC) techniques (using diverse\\u000a cooling\\/heating rate and modulation parameters) and effect of an annealing step (?30, ?20, or ?15°C, 30min) were assayed.\\u000a Transition was more evident using conventional DSC assays, cooling\\/heating rate: 10°C\\/min,

Valeria Tironi; Marie de Lamballerie-Anton; Alain Le-Bail

2009-01-01

36

DSC Study on Phase Transitions and Their Correlation with Properties of Overaged Al-Zn-Mg-Cu Alloys  

Microsoft Academic Search

This article investigates the phase transitions of complex quaternary Al-Zn-Mg-Cu alloys with Zr addition at overaged conditions. Differential scanning calorimetry (DSC) is employed to quantitatively analyze the phase transformation phenomena of a wide range of 7xxx series alloys through endothermic and exothermic reactions. The DSC observations detailing heat effect peaks and thermal parameters of eta' dissolution contain valuable information on

X. M. Li; M. J. Starink

2011-01-01

37

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

38

ANALYSIS OF A HEAT-FLUX DIFFERENTIAL SCANNING CALORIMETRY INSTRUMENTS  

SciTech Connect

Differential Scanning Calorimetry (DSC) measurements are used to estimate the fractional latent heat release during phase changes. There are temperature lags inherent to the instruments due to the temperature measurement at a different location than that of the sample and reference materials. Recently, Dong and Hunt[1] showed that significant improvement in estimating the fractional latent heat can be obtained when detailed simulations of the heat transfer within the instrument are performed. The Netzsch DSC 404C instrument, with a high accuracy heat capacity sensor, is considered in this study. This instrument had a different configuration than that studied by Dong and Hunt[1]. The applicability of Dong and Hunt's approach to this instrument is investigated. It was found that the DSC instrument could be described by numerous parameters but that model parameters were difficult to estimate. Numerical simulation results are presented and compared with experimental results for the fractional latent heat of a commercial A356 aluminum alloy.

Sabau, Adrian S [ORNL; Porter, Wallace D [ORNL

2007-01-01

39

Differential scanning calorimetry of water buffalo and cow milk fat in mozzarella cheese  

Microsoft Academic Search

The thermal profiles of the fat in mozzarella cheeses made from cow milk (CM) and water buffalo milk (WBM) were obtained by\\u000a differential scanning calorimetry (DSC). The DSC curves of mozzarella cheese made from WBM were distinguishable from those\\u000a of CM. The curves resembled those of the corresponding milk fats and could be divided into low-, medium-, and high-temperature\\u000a melting

Michael H. Tunick; Edyth L. Malin

1997-01-01

40

Thermal porosity analysis of croscarmellose sodium and sodium starch glycolate by differential scanning calorimetry  

Microsoft Academic Search

The aim of the study was to demonstrate the applicability of differential scanning calorimetry (DSC) on porosity analysis\\u000a for cellulose and starch. Croscarmellose sodium (CCS) and sodium starch glycolate (SSG) were allowed to sorb moisture in 85%,\\u000a 90%, 95%, and 100% relative humidity (RH) at 40°C for 24 hours. The pretreated samples were then subjected to DSC running\\u000a temperature ranging

Damrongsak Faroongsarng; Garnet E. Peck

2003-01-01

41

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

42

Modulated differential scanning calorimetry  

SciTech Connect

Modulated DSC (MDSC){sup tm} is a new patent-pending extension to conventional DSC which provides information about the reversing and nonreversing characteristics of thermal events. This additional information aids interpretation and allows unique insights into the structure and behavior of materials. Data presented will demonstrate three uses of MDSC. First, the overlapping crystallization peak and glass transition in a bilayer film of polycarbonate and PET are separated by MDSC. Second, the glass transition and endothermic relaxation of epoxy are separated. Third, MDSC gives a direct measurement of the sample heat capacity. The ability to separate reversing and nonreversing transitions, as well as the ability to directly measure heat capacity, offers thermal analysis another tool for solving tough materials characterization problems.

Sauerbrunn, S.R.; Crowe, B.S.; Reading, M. [TA Instruments Inc., New Castle, DE (United States)

1993-12-31

43

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

44

Differential scanning calorimetry and fluorescence study of lactoperoxidase as a function of guanidinium-HCl, urea and pH  

PubMed Central

The stability of bovine lactoperoxidase to denaturation by guanidinium-HCl, urea or high temperature was examined by differential scanning calorimetry (DSC) and tryptophan fluorescence. The calorimetric scans were observed to be dependent upon the heating scan rate, indicating that lactoperoxidase stability at temperatures near Tm is controlled by kinetics. The values for the thermal transition, Tm, at slow heating scan rate were 66.8, 61.1 and 47.2°C in the presence of 0.5, 1 and 2 M guanidinium-HCl, respectively. Extrapolated value for Tm in the absence of guanidinium-HCl is 73.7°C, compared with 70.2°C obtained by experiment; a lower experimental value without denaturant is consistent with distortion of the thermal profile due to aggregation or other irreversible phenomenon. Values for the heat capacity, Cp, at Tm and Ea for the thermal transition decrease under conditions where Tm is lowered. At a given concentration, urea is less effective than guanidinium-HCl in reducing Tm, but urea reduces Cp relatively more. Both fluorescence and DSC indicate that thermally denatured protein is not random coil. A change in fluorescence around 35°C, which was previously reported for EPR and CD measurements (Boscolo et al. Biochim. Biophys. Acta 1174 (2007) 1164–1172), is not seen by calorimetry, suggesting that a local and not global change in protein conformation produces this fluorescence change. PMID:20298816

ZELENT, Bogumil; SHARP, Kim A.; VANDERKOOI, Jane M.

2010-01-01

45

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. PMID:18835447

Salim, Nilshad N.; Feig, Andrew L.

2009-01-01

46

Calorimetry Optimised for Jets  

NASA Astrophysics Data System (ADS)

The physics programme for a coming electron linear collider is dominated by events with final states containing many jets, dijets from H, W, Z. We contend that, in the energy range under consideration, the best approach is to optimise the independent measurement of the tracks in the tracker, the photons in the electromagnetic calorimeter and the neutral hadrons in the calorimetry, together with a good lepton identification. This can be achieved with a good tracker and a high granularity calorimetry providing particle separation, through an efficient energy flow algorithm. But we do not contend that this is a universal panacea. Following that programme from the calorimetric side on hardware and software issues is the goal of the CALICE collaboration.

Videau, Henri; Brient, Jean-Claude

2002-01-01

47

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. PMID:21430954

Chiu, Michael H.; Prenner, Elmar J.

2011-01-01

48

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

49

MDSC and DSC studies on sol-gel lithium triborate glass and glass-ceramics: a comparison  

Microsoft Academic Search

Glasses prepared following a sol-gel route must be thermally treated to evacuate solvent and organic radicals. They often undergo phase transitions in the same temperature range where the weight losses occur. When applied to these systems, conventional differential scanning calorimetry (DSC) may lead to deceiving interpretations. In this paper the transformations of a sol-gel lithium triborate glass, annealed up to

Corrado Tomasi; Piercarlo Mustarelli; Eliana Quartarone; Renzo Pepi

1997-01-01

50

DMSO produces a new subgel phase in DPPC: DSC and X-ray diffraction study  

Microsoft Academic Search

Equilibrium phases and the kinetics of subgel phase transformation of dipalmitoylphosphatidylcholine (DPPC) hydrated with mixtures of dimethylsulfoxide (DMSO)\\/water have been studied using differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The rate of gel-to-subgel transformation is decreased with a small increase in X, the DMSO\\/water mole fraction, but then speeds up and becomes faster than in pure water by X

Stephanie Tristram-Nagle; Tisha Moore; Horia I. Petrache; John F. Nagle

1998-01-01

51

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

Microsoft Academic Search

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

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

1999-01-01

52

Differential scanning calorimetry in a piston-cylinder apparatus: Design and calibration  

NASA Astrophysics Data System (ADS)

We have designed and calibrated a piston-cylinder cell assembly suitable for conducting in situ measurements of enthalpies of phase transitions at elevated pressures by heat-flux differential scanning calorimetry (DSC). The high-pressure DSC detector consists of a Pt-Pt13% Rh thermopile wrapped around a frame of fired pyrophyllite. Four thermocouple junctions, arranged radially around the sample capsule, are connected in series, with four reference thermocouple junctions located 3 4 mm above the sample and embedded in thermally inert ceramic. A W-W25% Re control thermocouple is situated directly above the top of the sample; the whole detector assembly is enclosed in a 1.5 mm thick cylindrical ceramic sleeve located at the center of a 8 10 mm long “hot-zone” in the tapered graphite furnace. Using this detector design and cell assembly, we have observed the thermal signal associated with the fusion of Au at 0.5 and 1.2 GPa, and have calculated a calibration factor ( K) for this detector based on the gold melting curve of Mirwald and Kennedy (1979). Detector sensitivity decreases by a factor of four over this pressure-temperature interval. The reproducibility of the enthalpy of fusion of gold at 0.5 GPa suggests that detector geometry is reproducible from one experiment to the next, and thus confirms the viability of this particular detector design for quantitative DSC measurements. Subsequent experiments will assess the dependence of ( K) on temperature and pressure by measuring the enthalpies of fusion of additional metals (e.g., Ag, Cu, Al, Ge) and salts (e.g., NaCl, CsCl).

Rapp, Robert P.; Navrotsky, Alexandra

1993-06-01

53

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

SciTech Connect

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

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

2013-10-01

54

Sublimation enthalpies at 298.15 K using correlation gas chromatography and differential scanning calorimetry measurements  

E-print Network

. The sublimation enthalpies of azulene and 1,8-cyclotetradecadiyne are also measured by head-space analysis and torsion effusion, head-space ana- lysis and calorimetry [2]. Many of these techniques require both are measured both by DSC-CGC and head-space analysis. Thermochimica Acta 313 (1998) 101±110 *Corresponding

Chickos, James S.

55

Two DSC Glass Transitions in Miscible Blends of Polyisoprene / Poly(4-tert-butyl styrene)  

NASA Astrophysics Data System (ADS)

Conventional and temperature modulated differential scanning calorimetry experiments have been carried out on miscible blends of polyisoprene (PI) and poly(4-tert-butyl styrene) (P4tBS) over a broad composition range. This system is characterized by an extraordinarily large component Tg difference (˜215 K) between the two homopolymers. Two distinct calorimetric Tgs were observed in blends with an intermediate composition range (25%˜50% PI) by both conventional and temperature modulated DSC. Good agreement was found between the Tg values measured by the two methods. Fitting of the measured Tgs to the Lodge-McLeish model gives a ?self of 0.62˜0.64 for PI in this blend and 0.02˜0.05 for P4tBS. The extracted ?self for PIis comparable to reported values for PEO in blends with PMMA and is significantly larger than those reported for other PI blends with smaller component Tg differences. This observation suggests the presence of a confinement effect in PI/P4tBS blends, which results in enhanced fast component dynamics below the effective Tg of the slow component.

Zhao, Junshu; Sun, Ye; Yu, Lian; Ediger, Mark

2009-03-01

56

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

57

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

58

OXIDATIVE STABILITY OF BIODIESEL BY DYNAMIC MODE PRESSURIZED-DIFFERENTIAL SCANNING CALORIMETRY (P-DSC)  

Technology Transfer Automated Retrieval System (TEKTRAN)

Biodiesel, an alternative diesel fuel made from transesterification of vegetable oils or animal fats, is composed of saturated and unsaturated long-chain fatty acid alkyl esters. During long-term storage, oxidation caused by contact with ambient air presents legitimate concerns for monitoring fuel ...

59

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

60

The thermal analysis of nonezymatic glycosylation of human serum albumin: differential scanning calorimetry and circular dichroism studies  

Microsoft Academic Search

The stability of human serum albumin (HSA) is studied before and after incubation with glucose utilizing differential scanning Calorimetry (DSC) and circular dichroism (CD) techniques. The incubation of HSA with glucose results in its nonenzymatic glycosylation that is glycosylated HSA (GHSA) formed in glucose concentrations (8.25, 16.5 and 27.5mM) in a temperature dependent manner. The DSC profiles of GHSA samples,

A. Mohamadi-Nejad; A. A. Moosavi-Movahedi; S. Safarian; M. H. Naderi-Manesh; B. Ranjbar; B. Farzami; H. Mostafavi; M. B. Larijani; G. H. Hakimelahi

2002-01-01

61

DSC analysis of the effect of processing technique on the dissolution\\/precipitation reactions in a hypereutectic Al?Si alloy  

Microsoft Academic Search

In the present study, the effect of primary processing route on the dissolution and precipitation reactions in a commercial\\u000a Al?Si alloy (designated as A390) is investigated using differential scanning calorimetry (DSC). The Al?Si alloy selected for\\u000a the present investigation was processed using conventional casting and spray atomization and deposition routes. The results\\u000a of differential scanning calorimetry conducted on the as-processed

M. Gupta; Y. Li; Y. Wu; E. J. Lavernia

1995-01-01

62

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. PMID:24523644

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

2014-01-01

63

Oxidation behaviour of mechanically activated Mn{sub 3}O{sub 4} by TGA/DSC/XRPD  

SciTech Connect

The effect of high energy milling on the solid-state reactions taking place in Mn{sub 3}O{sub 4} has been studied. Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC) have been employed to study the solid-state reaction occurring under air in the temperature range between room temperature (rt) and 1100 deg. C. X-ray Powder Diffractometry (XRPD) has been used to ascertain the chemical nature of the transformations brought into evidence by thermo-analysis.

Berbenni, V.; Marini, A

2003-11-26

64

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. PMID:19118541

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

2013-01-01

65

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

66

DSC Logistics Internship/Coop Program DSC Logistics is currently starting an internship/coop program and is looking to  

E-print Network

DSC Logistics Internship/Coop Program DSC Logistics is currently starting an internship. Candidates with Supply Chain Management, Analytics, Transportation/Logistics, or Marketing Communications.stanley@dsclogistics.com. For more information about DSC visit www.dsclogistics.com. #12;DSC Logistics, a leading supply chain

Heller, Barbara

67

Melting of Single Lipid Components in Binary Lipid Mixtures: A Comparison between FTIR Spectroscopy, DSC and Monte Carlo Simulations  

E-print Network

Monte Carlo (MC) Simulations, Differential Scanning Calorimetry (DSC) and Fourier Transform InfraRed (FTIR) spectroscopy were used to study the melting behavior of single lipid components in two-component membranes of 1,2-Dimyristoyl-D54-sn-Glycero-3-Phosphocholine (DMPC-d54) and 1,2-Distearoyl-sn-Glycero-3-Phosphocholine (DSPC). Microscopic information on the temperature dependent melting of the single lipid species could be investigated using FTIR. The microscopic behavior measured could be well described by the results from the MC simulations. These simulations also allowed to calculate heat capacity profiles as determined with DSC. These ones provide macroscopic information about melting enthalpies and entropy changes which are not accessible with FTIR. Therefore, the MC simulations allowed us to link the two different experimental approaches of FTIR and DSC.

Fidorra, M; Seeger, H M

2007-01-01

68

Thermal characterization and phase behavior of cornstarch studied by differential scanning calorimetry  

Microsoft Academic Search

A cornstarch–water system was characterized by differential scanning calorimetry (DSC). Glass transition and melting transitions of starch crystals and amylose–lipid complexes were observed in native cornstarch with moisture content (MC) between 11.9% and 24%. At medium to high MC levels, the glass transition was not detectable, but melting of ice and gelatinization of starch (G endotherm) were observed. The gelatinized

Zhikai Zhong; X. Susan Sun

2005-01-01

69

Thermal characteristics and regeneration analyses of adsorbents by differential scanning calorimetry and scanning electron microscope  

Microsoft Academic Search

Volatile organic compounds (VOCs) are the main factors involved in pollution control and global warming in industrialized\\u000a nations. Various treatment methods involving incineration, adsorption, etc., were employed to reduce VOCs concentration. Various\\u000a absorbents, such as activated carbon, zeolite, silica gel or alumina, and so on were broadly used to adsorb VOCs in various\\u000a industrial applications. Differential scanning calorimetry (DSC) was

Chung-Hwei Su; Sheng-Hung Wu; Sun-Ju Shen; Gong-Yih Shiue; Yih-Weng Wang; Chi-Min Shu

2009-01-01

70

Detection of pig and buffalo body fat in cow and buffalo ghees by differential scanning calorimetry  

Microsoft Academic Search

Adding small amounts of pig or buffalo body fat to cow or buffalo ghee results in the appearance of an extra peak located\\u000a at high temperature in the melting and crystallization curves as determined by the differential scanning calorimetry (DSC)\\u000a technique. Ghee adulterations with these animal fats at levels down to 5% are clearly seen in the crystallization diagrams.\\u000a Quantitative

P. Lambelet; N. C. Ganguli

1983-01-01

71

Interactions of Starch and Sugar Water Measured by Electron Spin Resonance and Differential Scanning Calorimetry  

Microsoft Academic Search

Cereal Chem. 67(3):286-291 Electron spin resonance (ESR) was used to evaluate the mobility of of water was reduced or after heat treatment of starch-sugar-water mix- water in starch-water mixtures (12-50% H2 0); ESR and differential scan- tures. The sugars progressively raised the temperature of starch gelatiniza- ning calorimetry (DSC) were used to study the effect of different sugars tion measured

J. M. JOHNSON; E. A. DAVIS; J. GORDON

72

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

73

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

74

The deconvolution of differential scanning calorimetry unfolding transitions.  

PubMed

This paper is a review of a process for deconvolution of unfolding thermal transitions measured by differential scanning calorimetry. The mathematical background is presented along with illustrations of how the unfolding data is processed to resolve the number of sequential transitions needed to describe an unfolding mechanism and to determine thermodynamic properties of the intermediate states. Examples of data obtained for a simple two-state unfolding of a G-quadruplex DNA structure derived from the basic human telomere sequence, (TTAGGG)4TT are used to present some of the basic issues in treating the DSC data. A more complex unfolding mechanism is also presented that requires deconvolution of a multistate transition, the unfolding of a related human telomere structure, (TTAGGG)12 TT. The intent of the discussion is to show the steps in deconvolution, and to present the data at each step to help clarify how the information is derived from the various mathematical manipulations. PMID:25498005

Spink, Charles H

2015-04-01

75

Nanoscale Calorimetry of Isolated Polyethylene Single Crystals  

E-print Network

Nanoscale Calorimetry of Isolated Polyethylene Single Crystals A. T. KWAN, M. YU. EFREMOV, E. A-film differential scanning calorimetry to investigate the melt- ing of isolated polyethylene single crystals of lamellar single crystals of polyethylene (PE). We obtain thickness, diffraction, and calorimetry data

Allen, Leslie H.

76

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

PubMed

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 Sentalloy (GAC International, Islandia, NY), 35 degrees C Copper Ni-Ti (Ormco, Glendora, Calif) and Nitinol SE (3M Unitek, Monrovia, Calif). In the oral environment, the first 2 superelastic wires have shape memory, and the third wire has superelastic behavior but not shape memory. All wires had cross-section dimensions of 0.016 x 0.022 in. Archwires in the as-received condition and after bending 135 degrees were cut into 5 or 6 segments for test specimens. TMDSC analyses (Model 2910 DSC, TA Instruments, Wilmington, Del) were conducted between -125 degrees C and 100 degrees C, using a linear heating and cooling rate of 2 degrees C per min, an oscillation amplitude of 0.318 degrees C with a period of 60 seconds, and helium as the purge gas. For all 3 wire alloys, strong low-temperature martensitic transformations, resolved on the nonreversing heat-flow curves, were not present on the reversing heat-flow curves, and bending appeared to increase the enthalpy change for these peaks in some cases. For Neo Sentalloy, TMDSC showed that transformation between martensitic and austenitic nickel-titanium, suggested as occurring directly in the forward and reverse directions by conventional DSC, was instead a 2-step process involving the R-phase. Two-step transformations in the forward and reverse directions were also found for 35 degrees C Copper Ni-Ti and Nitinol SE. The TMDSC results show that structural transformations in these wires are complex. Some possible clinical implications of these observations are discussed. PMID:14560268

Brantley, William A; Iijima, Masahiro; Grentzer, Thomas H

2003-10-01

77

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

78

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

E-print Network

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

Cirne, Walfredo

79

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

2014-08-01

80

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

81

Differential scanning calorimetry as a tool to investigate the transfer of anticancer drugs to biomembrane model.  

PubMed

Different anticancer drugs clinically approved by international regulatory organizations present poor water solubility and low stability after systemic injection. Their administration requires suitable carriers capable of maximizing therapeutic efficacy. Lipid and polymeric nanotherapeutics, particularly liposomes, are widely used to deliver chemotherapeutics in the clinic. The interaction between chemotherapeutics and biocompatible lipids and polymers can affect their efficacy and play a pivotal role in chemotherapy. Phospholipids are the main components of liposomes and their interactions with therapeutic agents are widely investigated in the pharmaceutical field using differential scanning calorimetry (DSC). In this work, DSC was exploited to investigate the interaction between hydrophobic chemotherapeutics, i.e. docetaxel, tamoxifen and lapatinib, with lipid vesicles. Lipid carriers are prepared using dimyristoylphosphatidylcholine (DMPC), a phosphatidylcholine derivative, showing the same physicochemical features of the main lipids in the biological membranes. DMPC was used as a biological membrane model to evaluate interaction, passage, diffusion, and adsorption of chemotherapeutics. These processes were evaluated through the variation of thermotropic parameters of the biological membrane model. DSC studies were carried out in heating and cooling mode. Results demonstrated a modification of calorimetric curves and this effect is strictly related to the molar fraction and physicochemical features of chemotherapeutics. Furthermore, the interaction between chemotherapeutics and biological membranes affects their internalization and distribution inside tumors and this process depends on gel-liquid crystal transition of phospholipids. DSC results provide suitable information about this effect and can be used as tool to predict further interaction between chemotherapeutics and biological membranes. PMID:23651164

Sarpietro, Maria Grazia; Accolla, Maria Lorena; Celia, Christian; Grattoni, Alessandro; Castelli, Francesco; Fresta, Massimo; Ferrari, Mauro; Paolino, Donatella

2013-08-01

82

Cone Calorimetry Mark McKinnon  

E-print Network

is tested. 3. Calibrate the heat release rate measurement against a standard size methane flame (5 kW) 4 with the test until 2 minutes after any of the following occur: 1. Flaming and other signs of combustion cease 2Cone Calorimetry Mark McKinnon Lab Test Methods Day 2014 6/25/2014 #12;Background Cone Calorimetry

Shapiro, Benjamin

83

The development of heat flow calorimetry as a tool for process optimization and process safety  

Microsoft Academic Search

Classical thermo-analytical micro methods (DTA, DSC) are still very useful for process work, but medium scale instruments\\u000a based on heat flow measurement are attaining an increasingly important role in this domain.\\u000a \\u000a \\u000a As in many areas, development of reaction calorimetry for industrial applications was driven by needs and by available means\\u000a (technical capabilities).\\u000a \\u000a \\u000a \\u000a The needs have been fairly constant over the

W. Regenass

1997-01-01

84

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

SciTech Connect

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

Weidenbaum, S.S.

1991-01-01

85

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

86

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

87

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

88

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

89

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

90

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

91

Primary crystallization process of amorphous Al 88Ni 6Sm 6 alloy investigated by differential scanning calorimetry and by electrical resistivity  

Microsoft Academic Search

The primary crystallization process of ?-Al nanoparticles from the amorphous Al88Ni6Sm6 ribbon was investigated by differential scanning calorimetry (DSC) under non-isothermal condition and by electrical resistivity (ER) measurements under both isothermal and non-isothermal conditions. The apparent activation energy, Ea, was measured to be 249.9±12.5kJ\\/mol by DSC and 245.7±12.3kJ\\/mol by ER. The local activation energy, Ec, was also evaluated and was

Fan Sun; Thierry Gloriant

2009-01-01

92

Reliable determination of freeze-concentration using DSC  

Microsoft Academic Search

The objective of this study was to determine the feature of a DSC endotherm that can be most reliably used to determine the composition of a freeze-concentrate. Samples (3–10mg) of sucrose in water (0–60%, w\\/v) were frozen and then heated (at 0.2–2.0°C\\/min) on a DSC. The peak (Tpeak) and offset (Toffset) temperatures were obtained from the melt endotherms. A freezing

Bakul S. Bhatnagar; Stephane Cardon; Michael J. Pikal; Robin H. Bogner

2005-01-01

93

The DSC thermal analysis of crystallization behavior in palm oil  

Microsoft Academic Search

Polymorphic behavior of palm oil crystals was studied by DSC isothermal analysis and microscopic observation. Different crystal\\u000a forms developed specific spherulites depending on the degree of super-cooling from the melt. The A-form crystal was capable\\u000a of forming a dotted spherulite and the B-form crystal of forming a dendritic spherulite. Experimental results of B form crystallization\\u000a studied by the DSC and

K. Kawamura

1979-01-01

94

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

95

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

96

Forward Proton Calorimetry at PHOBOS  

NASA Astrophysics Data System (ADS)

Centrality is a crucial parameter for understanding the dynamics of heavy ion collisions. To provide additional centrality information, the PHOBOS experiment commissioned two hadronic calorimeters for the deuteron-gold run at RHIC. These new detectors are comprised of lead-scintillator modules originally constructed for the E864(AGS) experiment. They complement the experiment's ZDC detectors, which observe fragmentation neutrons, by observing fragmentation as well as struck protons. These protons have beam or near-beam velocity and are bent into the calorimeters by RHIC accelerator magnets. The installation and performance of these detectors will be discussed, and results using the detectors will be reviewed.

Reed, Corey

2003-10-01

97

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

98

Using Visible and Near-Infrared Reflectance Spectroscopy and Differential Scanning Calorimetry to Study Starch, Protein, and Temperature Effects on Bread Staling  

Microsoft Academic Search

Cereal Chem. 81(2):249-254 Starch, protein, and temperature effects on bread staling were inves- tigated using visible and near-infrared spectroscopy (NIRS) and differ- ential scanning calorimetry (DSC). Bread staling was mainly due to amylopectin retrogradation. NIRS measured amylopectin retrogradation accurately in different batches. Three important wavelengths, 970 nm, 1,155 nm, and 1,395 nm, were associated with amylopectin retrogra- dation. NIRS followed

Feng Xie; Floyd E. Dowell; Xiuzhi S. Sun

2004-01-01

99

FTIR and DSC studies on gamma irradiated P(VdF-HFP) fluoropolymers applied to dosimetry  

NASA Astrophysics Data System (ADS)

Radiation effects on semicrystalline poly(fluorovinylidene- co-hexafluoropropylene) copolymer [P(VdF-HFP)] induced by high-energy irradiation were investigated. Films with 150 ?m thickness were irradiated with gamma doses ranging from 1.0 kGy to 3.0 MGy. Fourier transform infrared (FTIR) spectroscopy was used to follow the radio-induction of new molecular bonds. Differential scanning calorimetry (DSC) was employed to study the crystalline degradation of the irradiated samples. P(VdF-HFP) copolymers have fluorinated monomers [-CF 2-CF-CF 3-] randomly added to the [-CH 2-CF 2-] main chain of PVdF homopolymer. In this case, the [-CF 3-] molecular bonds are branched to the main chain. There is an increasing interest about the effect of high gamma radiation dose on the P(VdF-HFP) radiolysis, once it could enhance some of their already known interesting properties such as biomedical applications and electrostrictive transducers/actuators. FTIR spectroscopic data revealed two optical absorption bands at 1730 and 1754 cm -1 whose intensities are unambiguously related to gamma delivered dose ranging from 0.0 to 1000 kGy. Fading analysis has demonstrated no loss of signal until 11 months after irradiation. DSC and XRD data revealed a continuous decrease in both the melting latent heat and crystalline dimensions for doses ranging from 250 to 3000 kGy. Because of the low fading and the linear behavior with respect to delivered gamma doses of the absorption band at 1754 cm -1, P(VdF-HFP) copolymers are good candidates for being explored for high gamma dose dosimetry application.

Liz, O. S. R.; Medeiros, A. S.; Faria, L. O.

2011-12-01

100

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

101

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

102

Glass transition and crystallization kinetics of CsLiB 6O 10 glasses by differential scanning calorimetry  

NASA Astrophysics Data System (ADS)

Transparent glasses of CsLiB 6O 10 (CLBO) were fabricated via the conventional melt-quenching technique. The amorphous and the glassy characteristics of the as-quenched samples were, respectively, established by X-ray powder diffraction (XRD) and differential scanning calorimetry (DSC). To evaluate the activation energies for the glass transition and crystallization of these glasses, DSC runs were made at different heating rates. The value of the Avrami exponent, n, was found to be 3.5±0.3, suggesting a mixed transformation mechanism (two- and three-dimensional crystal growth). The average values of the activation energies associated with the glass transition and crystallization of CLBO glasses were 670±4 and 341±7 kJ/mol, respectively. Values of the kinetics parameters obtained using isothermal and non-isothermal techniques were in excellent agreement.

Vaish, Rahul; Varma, K. B. R.

2007-09-01

103

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

PubMed

Raman scattering and differential scanning calorimetry (DSC) measurements have been carried out on four mixed tellurium-zinc oxide (TeO(2))(1 - x)(ZnO)(x) (x = 0.1, 0.2, 0.3, 0.4) glasses under variable temperature, with particular attention being given to the respective glass transition region. From the DSC measurements, the glass transition temperature T(g) has been determined for each glass, showing a monotonous decrease of T(g) with increasing ZnO content. The Raman study is focused on the low-frequency band of the glasses, the so-called boson peak (BP), whose frequency undergoes an abrupt decrease at a temperature T(d) very close to the respective T(g) values obtained by DSC. These results show that the BP is highly sensitive to dynamical effects over the glass transition and provides a means for an equally reliable (to DSC) determination of T(g) in tellurite glasses and other network glasses. The discontinuous temperature dependence of the BP frequency at the glass transition, along with the absence of such a behaviour by the high-frequency Raman bands (due to local atomic vibrations), indicates that marked changes of the medium range order (MRO) occur at T(g) and confirms the correlation between the BP and the MRO of glasses. PMID:21386447

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

2010-05-19

104

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

Microsoft Academic Search

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

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

2009-01-01

105

Liquid argon calorimetry for the SSC  

SciTech Connect

Liquid argon calorimetry is a mature technique. However, adapting it to the challenging environment of the SSC requires a large amount of R D. The advantages of the liquid argon approach are summarized and the issues being addressed by the R D program are described. 18 refs.

Gordon, H.A.

1990-01-01

106

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

107

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

108

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. PMID:17671974

Feig, Andrew L.

2008-01-01

109

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

110

Modulated differential scanning calorimetry: 4. Miscibility and glass transition behaviour in poly(methyl methacrylate) and poly(epichlorohydrin) blends  

Microsoft Academic Search

The differential of heat capacity signal, dCp\\/dT, from modulated-temperature differential scanning calorimetry (M-T d.s.c.) was used to elucidate the miscibility and glass transition behaviour of poly(methyl methacrylate) (PMMA) and poly(epichlorohydrin) (PECH) blends. The conclusion reached was the same as that reported by Higgins and co-workers (Clark, J.N., Higgins, J.S., Kim, C.K. and Paul, D.R. Polymer 1992, 33, 3137) from small-angle

M. Reading

1996-01-01

111

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

SciTech Connect

Differential Scanning Calorimetry (DSC) studies on phase transitions of the pure liquid crystalline material N-4-methoxybenzylidene-4-butylaniline (MBBA) and mixtures of MBBA and the amphiphile Stearic Acid (StA) show significant changes in the behavior of mixture from pure MBBA, as regards the nematic-isotropic (N-I) transition temperature (T{sub c}) and other thermodynamic parameters like enthalpy, specific heat and activation energy with concentration of StA. In particular, the convexity of the Arrhenius plot in pure MBBA vanishes with StA concentration pointing to the formation of a new, perhaps 'nematic-like', phase in the mixtures.

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

2014-04-24

112

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

113

Thermal Degradation of ligno-cellulosic fuels: DSC and TGA studies V. Leroy, D. Cancellieri and E. Leoni*  

E-print Network

Thermal Degradation of ligno-cellulosic fuels: DSC and TGA studies V. Leroy, D. Cancellieri and E studies on ligno-cellulosic fuels. Around 638 K and 778 K, two dominating and overlapped exothermic peaks to classify the fuels according to the heat released and the rate constant of each reaction. TGA experiments

Paris-Sud XI, Université de

114

Fast Forward Calorimetry for CMS  

NASA Astrophysics Data System (ADS)

The CMS experiment at the LHC will study heavy ion and p-p collisions at 5 and 14 TeV respectively. The CMS heavy ion group has designed and built a Zero Degree Calorimeter (ZDC), to measure the topology of these collisions. This is part of a general effort in CMS to study low X physics and dense gluonic systems such as the Color Glass Condensate. The calorimeters are comprised of electromagnetic (EM) and hadronic sections with the Berkely shower maximum detector in between. The EM section is segmented transverse to the beam while the hadronic portion is segmented along the beam axis. For p-p collisions, we will study pomeron and odderon production since these are sensitive to the gluonic component of the proton wave function. For heavy ion collisions, we will measure the centrality of the events and provide a fast trigger for ultra-peripheral collisions. I will report on results from our recent beam test at CERN and extrapolate the ZDC's performance to LHC energies.

Snyder, Jessica

2006-10-01

115

The Impact of Structural Recovery on Dyanamic DSC Measurements: Tool- Narayanaswamy Model Calculations for Typical Polymers  

NASA Astrophysics Data System (ADS)

It is well known that structural recovery in polymeric glasses leads to highly nonlinear events, such as the enthalpy overshoot, in non-isothermal experiments. One common model for describing these events is the Tool-Narayanaswamy (TN) equation. Here we apply the TN equation to analyze typical modulated DSC experiments and examine the influence of the material nonlinearities on the dynamic heat flow. We also study the effects of nonlinearity on the reversing and non-reversing heat flows and compare the values of Cp obtained from the TN model with those expected from the MDSC when the material nonlinearities are ignored.

Simon, Sindee L.; McKenna, Gregory B.

1997-03-01

116

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

117

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

118

Technical decision making with higher order structure data: utilization of differential scanning calorimetry to elucidate critical protein structural changes resulting from oxidation.  

PubMed

Differential scanning calorimetry (DSC) is a useful tool for monitoring thermal stability of the molecular conformation of proteins. Here, we present an example of the sensitivity of DSC to changes in stability arising from a common chemical degradation pathway, oxidation. This Note is part of a series of industry case studies demonstrating the application of higher order structure data for technical decision making. For this study, six protein products from three structural classes were evaluated at multiple levels of oxidation. For each protein, the melting temperature (Tm ) decreased linearly as a function of oxidation; however, differences in the rate of change in Tm , as well as differences in domain Tm stability were observed across and within structural classes. For one protein, analysis of the impact of oxidation on protein function was also performed. For this protein, DSC was shown to be a leading indicator of decreased antigen binding suggesting a subtle conformation change may be underway that can be detected using DSC prior to any observable impact on product potency. Detectable changes in oxidized methionine by mass spectrometry (MS) occurred at oxidation levels below those with a detectable conformational or functional impact. Therefore, by using MS, DSC, and relative potency methods in concert, the intricate relationship between a primary structural modification, changes in conformational stability, and functional impact can be elucidated. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:1548-1554, 2015. PMID:25561411

Arthur, Kelly K; Dinh, Nikita; Gabrielson, John P

2015-04-01

119

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

120

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

121

Detection of fungal degradation at low weight loss by differential scanning calorimetry  

SciTech Connect

A thermo-analytical method to detect incipient fungal degradation was investigated. Hybrid poplar (Populus maximowiczii x trichocarpa) specimens were degraded by the brown-rot fungus Lenzites trabea and analyzed at five sequential, 3-day intervals to a weight loss of 5%. To measure the extent of decay, cold water, hot water, and sodium hydroxide solubilities, ethanol-benzene extractive content as well as lignin, holocellulose, and ..alpha..-cellulose were determined. Viscometric analysis was conducted to determine changes in the weight average degree of polymerization (DPw), and thermal analysis by differential scanning calorimetry (DSC) was performed to determine endothermic transitions in the whole decayed wood, extractive-free wood, and holo- and ..alpha..-cellulose. Chemical analysis provided results consistent with those expected in wood decayed by a brown-rot fungus. DPw changes of both holo- and ..alpha..-cellulose were significant with regard to decay interval. Analysis of DSC data revealed that this methodology was a reliable means of evaluating fungal degradation in extractive-free wood and holo- and ..alpha..-cellulose preparations from the decayed wood but not the whole wood. 23 references.

Baldwin, R.C.; Streisel, R.C.

1985-07-01

122

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

PubMed

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

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

2012-12-01

123

Lead tungstate (PbWO 4) scintillators for LHC EM calorimetry  

Microsoft Academic Search

This report describes the work carried out in order to analyse the properties of PbWO4 crystals as scintillators and to determine the perspectives of their use in calorimetry in Large Hadron Collider (LHC) experiments. The scintillation mechanism in PWO crystals is explained and the properties connected with their use as scintillators are analysed both for undoped and Nb doped crystals.

P. Lecoq; I. Dafinei; E. Auffray; M. Schneegans; M. V. Korzhik; O. V. Missevitch; V. B. Pavlenko; A. A. Fedorov; A. N. Annenkov; V. L. Kostylev; V. D. Ligun

1995-01-01

124

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

125

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

PubMed

This paper describes the use of Differential Scanning Calorimetry (DSC) to evaluate the impact of varying mix ratios of bio-oil (pyrolysis oil) and bio-diesel on the oxidation stability and on some cold flow properties of resulting blends. The bio-oils employed were produced from the semi-continuous Auger pyrolysis of pine pellets and the batch pyrolysis of pine chips. The bio-diesel studied was obtained from poultry fat. The conditions used to prepare the bio-oil/bio-diesel blends as well as some of the fuel properties of these blends are reported. The experimental results suggest that the addition of bio-oil improves the oxidation stability of the resulting blends and modifies the crystallization behavior of unsaturated compounds. Upon the addition of bio-oil an increase in the oxidation onset temperature, as determined by DSC, was observed. The increase in bio-diesel oxidation stability is likely to be due to the presence of hindered phenols abundant in bio-oils. A relatively small reduction in DSC characteristic temperatures which are associated with cold flow properties was also observed but can likely be explained by a dilution effect. PMID:20307976

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

2010-08-01

126

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

127

Water distribution studies within cellulose ethers using differential scanning calorimetry. 2. Effect of polymer substitution type and drug addition.  

PubMed

The distribution of water within gels composed of a range of cellulose ether polymers of similar molecular weights (viscosity grades of 4000-6000 cP) but varying substitution types and levels was assessed by differential scanning calorimetry (DSC). Water loosely bound to the polymer was detected as one or more events appearing at the low-temperature side of the main endotherm for the melting of free water in DSC scans. Polymer substitution types and levels, and added drugs (50 mM propranolol hydrochloride or 50 mM diclofenac sodium) influenced the appearance of these melting events. Hydroxypropylcellulose (HPC) and hydroxypropylmethylcellulose (HPMC F4M) gels showed behavior different to that of the other polymers studied. It is thought that any water binding to HPC gels is tightly attached and is not visible as pre-endothermic events on DSC scans. The amount of water bound per polymer repeating unit (PRU) was influenced by and related to the degree of hydrophilic and hydrophobic substitution on the polymer backbone and by the inclusion of either drug. HPC gels had the highest bound water content after 96 h and this was probably related to the high percentage of hydrophilic hydroxypropoxyl substitutions in this polymer. In contrast, methylcellulose (MC A4M) had the lowest bound water content after 96 h storage, and this was explained by the lack of hydrophilic hydroxypropoxyl substitutions in the polymer. PMID:10430545

McCrystal, C B; Ford, J L; Rajabi-Siahboomi, A R

1999-08-01

128

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

129

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

130

Electronics for calorimetry: An overview of requirements  

SciTech Connect

Calorimetry in large detectors at LHC poses some requirements on readout electronics which are quite different than for central tracking and muon tracking. The main distinction is, (a) in the large dynamic range of the energies to be measured; and (b) uniformity of response and accuracy of calibration over the whole detector. As in all other functions of the detector, low noise is essential. High luminosity results in pileup effects, which are present in every measurement, and in high radiation for front and forward parts of the calorimeter. Power dissipation and cooling is a concern as in any other detector component, in some respects only more so, since all the elements of the signal processing chain require more power due to the large dynamic range, speed of response, high precision and low noise required. The key requirements on the calorimetry readout electronics are briefly discussed here, with an emphasis on the dynamic range. While there are quite significant differences in the principles and technology among the crystals, tiles with fibers and liquid ionization, the signal is finally reduced to a charge measurement from a capacitive source in all three cases, and the signal processing chain becomes remarkably identical.

Radeka, V.

1995-10-01

131

Prospects for and tests of hadron calorimetry with silicon  

SciTech Connect

Hadron calorimetry with silicon may provide crucial capabilities in experiments at the high luminosity, high energy colliders of the future, particularly due to silicon's fast intrinsic speed and absolute calibration. The important underlying processes of our understanding of hadron calorimeters are reviewed to set the framework for the presentation of recent calculations of the expected performance of silicon detector based hadron calorimeters. Such devices employing uranium are expected to achieve the compensation condition (that is, the ratio of the most probable electron signal to hadron signal (e/h) is approx.1.0) based on the understanding that has been derived from the uranium-liquid argon and uranium-plastic scintillator systems. In fact, even lead-silicon calorimeters are found to achieve the attractive value for the e/h ratio of 1.16 at 10 GeV. An experimental test of these predictions is underway at CERN by the SICAPO Collaboration. 64 refs., 19 figs.

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

1989-03-01

132

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

133

DSC study of the decomposition of azodicarbonamide in different media  

Microsoft Academic Search

The decomposition of azodicarbonamide (Genitron AC-2) in the solid state was investigated by DSC. It was found that the decomposition under non-isothermal conditions can be described by the autocatalytic reaction scheme\\u000a$$X\\\\xrightarrow{{k_1 }}Y,X + Y\\\\xrightarrow{{k'_2 }}2Y$$\\u000a where the following dependences hold for the rate constants:\\u000a$$k_1 = 4.8 \\\\times 10^{19} e - {{243 600} \\\\mathord{\\\\left\\/ {\\\\vphantom {{243 600} {RT_s -

L. Rychlá; J. Rychlý; J. Svoboda; J. Šimonik

1984-01-01

134

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

135

Imaging hadron calorimetry for future Lepton Colliders  

NASA Astrophysics Data System (ADS)

To fully exploit the physics potential of a future Lepton Collider requires detectors with unprecedented jet energy and dijet-mass resolution. To meet these challenges, detectors optimized for the application of Particle Flow Algorithms (PFAs) are being designed and developed. The application of PFAs, in turn, requires calorimeters with very fine segmentation of the readout, so-called imaging calorimeters. This talk reviews progress in imaging hadron calorimetry as it is being developed for implementation in a detector at a future Lepton Collider. Recent results from the large prototypes built by the CALICE Collaboration, such as the Scintillator Analog Hadron Calorimeter (AHCAL) and the Digital Hadron Calorimeters (DHCAL and SDHCAL) are being presented. In addition, various R&D efforts beyond the present prototypes are being discussed.

Repond, José

2013-12-01

136

Study on biodegradation process of lignin by FTIR and DSC.  

PubMed

The biodegradation process of lignin by Penicillium simplicissimum was studied to reveal the lignin biodegradation mechanisms. The biodegradation products of lignin were detected using Fourier transform infrared spectroscopy (FTIR), UV-Vis spectrophotometer, different scanning calorimeter (DSC), and stereoscopic microscope. The analysis of FTIR spectrum showed the cleavage of various ether linkages (1,365 and 1,110 cm(-1)), oxidation, and demethylation (2,847 cm(-1)) by comparing the different peak values in the corresponding curve of each sample. Moreover, the differences (Tm and ?Hm values) between the DSC curves indirectly verified the FTIR analysis of biodegradation process. In addition, the effects of adding hydrogen peroxide (H2O2) to lignin biodegradation process were analyzed, which indicated that H2O2 could accelerate the secretion of the MnP and LiP and improve the enzymes activity. What is more, lignin peroxidase and manganese peroxidase catalyzed the lignin degradation effectively only when H2O2 was presented. PMID:25037100

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

2014-12-01

137

Reticulation of Aqueous Polyurethane Systems Controlled by DSC Method  

PubMed Central

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

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

2006-01-01

138

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. PMID:24421540

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

2013-01-01

139

Energy storage materials and coatings. DSC and flammability studies  

SciTech Connect

Several Energy Storage Materials (ESM`s) and more recently coatings have proven efficacious in supplemental, heating and cooling applications in building construction and could significantly reduce energy costs. The ESM absorbs heat as ambient temperature rises and releases it as ambient temperature falls. Coatings can reduce flammability and smoke production eliminating the undesirable properties of many of the early organic materials suggested for use. New materials including inorganics have better properties in many areas as well as improved thermal properties. Flammability Studies and Differential Scanning Calorimetry results will be discussed.

Babich, M.W.; Benrashid, R. [Florida Inst. of Technology, Melbourne, FL (United States)

1996-10-01

140

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

PubMed

I describe an interchangeable twin vessel (J, N) automatic glass recrystallizer that eliminates the time-consuming recovery and recycling of crystals for repeated recrystallization. The sample goes in the dissolution vessel J containing a magnetic stir-bar K; J is clamped to the upper joint H of recrystallizer body D. Empty crystallization vessel N is clamped to the lower joint M. Pure solvent is delivered to the dissolution vessel and the crystallization vessel via the head of the condenser A. Crystallization vessel is heated (P). The dissolution reservoir is stirred and heated by the solvent vapor (F). Continuous outflow of filtrate E out of J keeps N at a stable boiling temperature. This results in efficient dissolution, evaporation and separation of pure crystals Q. Pure solvent in the dissolution reservoir is recovered by suction. Empty dissolution and crystallization vessels are detached. Stirrer magnet is transferred to the crystallization vessel and the role of the vessels are then reversed. Evacuating mother liquor out of the upper twin vessel, the apparatus unit is ready for the next automatic recrystallization by refilling twin vessels with pure solvent. We show successive automatic recrystallization of acetaminophen from diethyl ether obtaining acetaminophen of higher melting temperatures than USP and JP reference standards by 8× automatic recrystallization, 96% yield at each stage. Also, I demonstrate a novel approach to the determination of absolute purity by combining the successive automatic recrystallization with differential scanning calorimetry (DSC) measurement requiring no reference standards. This involves the measurement of the criterial melting temperature T(0) corresponding to the 100% pure material and quantitative ?T in DSC based on the van't Hoff law of melting point depression. The purity of six commercial acetaminophen samples and reference standards and an eight times recrystallized product evaluated were 98.8 mol%, 97.9 mol%, 99.1 mol%, 98.3 mol%, 98.4 mol%, 98.5 mol% and 99.3 mol% respectively. PMID:21168556

Nara, Osamu

2011-01-24

141

Description of cooling water calorimetry and wall thermometry diagnostic at tokamak ASDEX-Upgrade  

NASA Astrophysics Data System (ADS)

Hardware and software of the cooling water calorimetry and the wall thermometry diagnostics at the tokamak ASDEX-Upgrade are described. These diagnostics were used to analyze the energy deposition on the first wall elements in ASDEX-Upgrade. The cooling water calorimetry system consists of 130 platinum resistor thermometers Pt-100 and 27 annular flow meters located in the cooling water system of the tokamak downstream and upstream near the individual cooling units. In addition to the cooling water calorimetry system in some sections of the torus a wall thermometry diagnostic was installed to reach a higher poloidal resolution of the energy deposition measurements. The electrical measuring signals from the sensors were amplified, converted into digital signals, multiplexed with a frequency of 500 Hz, and sent over a fiber optics system into the control room. There a transputer system consisting of five T800 transputers receives the signals and stores a complete set of data about every three seconds during the 10 minute pause between the shots. These raw data were sent into the data analysis system of the experiment and the deposited energy for each cooling unit was calculated. First experimental results of the cooling water calorimetry show toroidal and poloidal asymmetries in the energy deposition in the ASDEX-Upgrade walls.

Richter, Th.; Vernickel, H.

1992-08-01

142

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

NASA Astrophysics Data System (ADS)

Characterizing the status and stability of natural organic matter (NOM) is central to understanding the flux, attenuation and function of C in the biosphere. A diversity of stabilizing factors (climate, mineralogy, chemical recalcitrance) have required a range of analytical approaches and methods that are site or discipline specific making unified assessments difficult. Aggregated, these efforts support our working models of NOM as a dynamic body but, overall, lack analytical simplicity and reproducibility. In particular, the robustness and resolution to assess NOM across systems of increasing complexity is lacking. Calorimetry has been central to chemistry and material science characterizing a broad range of organic and inorganic materials and their mixtures illustrating composition, purity and stability. Differential scanning calorimetry - thermogravimetry (DSC-TG) provides the flexibility and resolution to quantify the complexity found within NOM with precise quantification of material mass loss (TG) and energetic (DSC) under controlled atmospheric and heating conditions. DSC-TG is data rich providing a range of qualitative and quantitative metrics: peak shape, exothermic energy yield, mass loss, and determination of enthalpy, to characterize NOM stability from low (dissolved organic carbon - DOC) through high (compost and soils) molecular weights (MW) at increasing levels of organo-metallic complexity. Our research investigates the influence of biochemical recalcitrance and its alteration by oxides employing three natural systems of varying complexity as experimental models: aquatic - DOC and DOC with metal flocculants (low MW - low complexity), compost - processed with and without metal oxides (mixed MW - increasing complexity) and forest soils - under varying management and litter inputs (mixed MW - most complexity). Samples were analyzed by DSC-TG (zero-air - 20 C/min - ambient to > 800C) and assessed for three temperature/exothermic reaction regions (200-350 C - nominally ‘labile’/low MW, 350-500 C - increasing recalcitrance/MW and 500-650 C - recalcitrant/high MW). Samples from all three systems show similar stability distributions with broader less resolved peaks for DOC and soil with intense more resolved peaks for mature compost. DOC flocculated with Iron (Fe) or aluminum (Al) broadened and shifted peak stability to higher temps doubling energy yield compared to DOC (least complex most change). Fe and Al oxides added during composting broadened peaks with shifts towards higher temps with more modest increases in energetic yield(increased complexity reduced change). Soils illustrate a broad and balanced distribution that is fairly robust to treatment or input (most complex least change). Generally metal oxides increased thermal stability and system complexity altering stability distributions towards the diverse and complex soil system. Is the complex and attenuating nature of soil the benchmark to quantify less stable and complex systems based on their components, alterations and metrics of thermal stability and order? Our research is an initial test of this idea supported by reproducible thermal metrics to assess the attenuation of C through natural systems.

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

2010-12-01

143

Advances in temperature derivative control and calorimetry  

NASA Astrophysics Data System (ADS)

Temperature stabilization by inertial feedback control has proven a powerful tool to create the ultrastable environment essential for high resolution calorimetry. A thermally insulated mass, connected to a base through Seebeck effect sensors (thermopiles) is used as a reference to control the base temperature. The thermopile signal is proportional to both the heat capacity of the reference mass and the derivative ?? of the base temperature ?. Using vacuum insulation and bismuth telluride thermopiles, we designed and tested temperature derivative sensors (TDSs) with sensitivities up to 3300 V s K-1. Standard industrial controllers with approximately ±1 ?V input noise and stability, permit control of temperature derivatives to ±3×10-10 K s-1. Single-cup thermoelectric calorimeters coupled to the TDS-controlled base permitted measurement of heat flow from samples in a power range from 3 ?W to 10 W with high accuracy (±100 ppm), resolution (±0.2 ?W), and reproducibility (±1 ?W). The design of two instruments is described in detail. Their performance is demonstrated on a variety of measurements, e.g., the determination of sample heat capacities with temperature ramp rates ??=±5×10-6 K s-1, the half-life of a 3 g tritium sample in a uranium getter bed, the decay heat of depleted uranium, and the heat evolution of epoxy resin.

Hemmerich, J. L.; Loos, J.-C.; Miller, A.; Milverton, P.

1996-11-01

144

Hadron sampling calorimetry, a puzzle of physics  

NASA Astrophysics Data System (ADS)

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

Brückmann, Hanno; Anders, Bernd; Behrens, Ulf

1988-01-01

145

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

PubMed

The solubility of drugs in polyethylene glycol 400 (PEG 400) was estimated and rank ordered using a differential scanning calorimetry (DSC) method and the Fox Equation. Drug-polymer binary mixtures of six compounds (Ibuprofen, Indomethacin, Naproxen, and three proprietary compounds: PC-1 through PC-3) with PEG 400 were heat treated using a three-cycle DSC method to establish a correlation between equilibrium solubility and temperature. Thermal events such as heat of fusion, heat of recrystallization and glass transition temperature, T(g), were used to calculate the drug solubility at multiple higher temperatures through the Fox Equation. Subsequently, a van't Hoff plot was constructed to estimate the drug solubility at room temperature, and the values were compared with those measured by HPLC. With the exception of Naproxen, room temperature solubilities of the remaining drug compounds in PEG 400 were determined by this thermal method approach, and compared with those measured by HPLC: 26.7% vs. 24.7% for Ibuprofen, 5.8% vs. 9.6% for Indomethacin, 3.1 % vs. 1.5% for PC-1, 2.3% vs. 1.3% for PC-2, and 1.4% vs. 0.2% for PC-3 in PEG 400. There was good concordance in solubility rank order estimates between the two methods. These collective results support the potential utility of the thermal method as an alternative to other methods for estimation of drug solubility in polymers which is an important determinant in the design of physically-stable amorphous systems. PMID:18825543

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

2009-01-01

146

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

SciTech Connect

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

Barbosa, Irineu; Larocca, Nelson M.; Hage, Elias [Dep. de Engenharia de Materiais, Universidade Federal de Sao Carlos, Sao Carlos, SP (Brazil); Plivelic, Tomas S.; Torriani, Iris L. [Laboratorio Nacional de Luz Sincrotron, Campinas, SP (Brazil); Mantovani, Gerson L. [Centro de Engenharia, Modelagem e Ciencias Sociais Aplicadas, Universidade Federal do ABC, 09090-400 Santo Andre, SP (Brazil)

2009-01-29

147

Water distribution studies within cellulose ethers using differential scanning calorimetry. 1. Effect of polymer molecular weight and drug addition.  

PubMed

Differential scanning calorimetry (DSC) was employed to characterize the distribution of water in gels produced from a series of hydroxypropylmethylcelluloses (HPMC, Methocel K-series) of different molecular weights (i.e., different viscosity grades). The presence of loosely bound water was characterized as pre-endothermic events occurring at temperatures below the main melting endotherm of free water. Both the magnitude and occurrence of these pre-endothermic events were affected by polymer molecular weight and gel storage time. In addition, the amount of water bound to the polymer depended on polymer molecular weight and gel storage time. The temperature at which frozen water melted within the gels was dependent on polymer concentration, with a depression of extrapolated endothermic melting peak onset occurring with an increase in polymer concentration. The addition of propranolol hydrochloride or diclofenac sodium, as model drugs, affected both the occurrence of pre-endothermic events and the distribution of water within the gels. PMID:10430544

McCrystal, C B; Ford, J L; Rajabi-Siahboomi, A R

1999-08-01

148

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

PubMed

The association constant of a well-known streptavidin-biotin binding has only been inferred from separately measured kinetic parameters. In a single experiment, we obtained Ka 1??×??10(12) ?M(-1) by using a streptavidin-binding aptamer and ligand-displacement isothermal titration calorimetry. This study explores the challenges of determining thermodynamic parameters and the derived equilibrium binding affinity of tight ligand-receptor binding. Copyright © 2015 John Wiley & Sons, Ltd. PMID:25615849

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

2015-03-01

149

Characterization of fly ash from municipal solid waste incinerators using differential scanning calorimetry  

Microsoft Academic Search

Endothermic (in the 30–300°C range) and exothermic (in the 300–500°C range) processes were identified through differential scanning calorimetry experiments on fly ash in an air atmosphere. The endothermic processes are thermodynamically controlled and include the desorption of organic compounds along with a phase transition. Instead, exothermic processes are kinetically controlled and include two distinct combustion reactions. Their nature was confirmed

Massimo Tettamanti; Elena Collina; Marina Lasagni; Demetrio Pitea; Domenico Grasso; Carmelo La Rosa

1998-01-01

150

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

151

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

152

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

153

REDES DE COMPUTADORES UFPB / CCT / DSC / PSN, 2001 * Parte 3: TCP/IP -Endereamento * Pg. 1  

E-print Network

REDES DE COMPUTADORES © UFPB / CCT / DSC / PSN, 2001 * Parte 3: TCP/IP - Endereçamento * Pág. 1: Identificar unicamente uma rede na Internet; Identificar unicamente cada máquina de uma rede. ! Um endereço . 165 . 166 . 0 200 . 201 . 203 . 255 REDES DE COMPUTADORES © UFPB / CCT / DSC / PSN, 2001 * Parte 3

Cirne, Walfredo

154

DSC Evidence for Microstructure and Phase Transitions in Polyethylene Melts at High Temperatures  

E-print Network

DSC Evidence for Microstructure and Phase Transitions in Polyethylene Melts at High Temperatures polyethylenes of types HDPE, LDPE, and LLDPE. DSC data were obtained for a range of heating and cooling rates previous rheology findings of order and high-temperature transitions in polyethylene melts. Introduction

Hussein, Ibnelwaleed A.

155

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

PubMed

Fluorescence and differential scanning calorimetry (DSC) were used to study changes in the conformation of red kidney bean (Phaseolus vulgaris L.) protein isolate (KPI) under various environmental conditions. The possible relationship between fluorescence data and DSC characteristics was also discussed. Tryptophan fluorescence and fluorescence quenching analyses indicated that the tryptophan residues in KPI, exhibiting multiple fluorophores with different accessibilities to acrylamide, are largely buried in the hydrophobic core of the protein matrix, with positively charged side chains close to at least some of the tryptophan residues. GdnHCl was more effective than urea and SDS in denaturing KPI. SDS and urea caused variable red shifts, 2-5 nm, in the emission ?(max), suggesting the conformational compactness of KPI. The result was further supported by DSC characteristics that a discernible endothermic peak was still detected up to 8 M urea or 30 mM SDS, also evidenced by the absence of any shift in emission maximum (?(max)) at different pH conditions. Marked decreases in T(d) and enthalpy (?H) were observed at extreme alkaline and/or acidic pH, whereas the presence of NaCl resulted in higher T(d) and ?H, along with greater cooperativity of the transition. Decreases in T(d) and ?H were observed in the presence of protein perturbants, for example, SDS and urea, indicating partial denaturation and decrease in thermal stability. Dithiothreitol and N-ethylmaleimide have a slight effect on the thermal properties of KPI. Interestingly, a close linear relationship between the T(d) (or ?H) and the ?(max) was observed for KPI in the presence of 0-6 M urea. PMID:21126074

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

2011-01-12

156

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

SciTech Connect

The oxidation in air of high-purity Al foil was studied as a function of temperature using Thermogravimetric Analysis with Differential Scanning Calorimetry (TGA/DSC). The rate and/or extent of oxidation was found to be a non-linear function of the temperature. Between 650 and 750 %C2%B0C very little oxidation took place; at 850 %C2%B0C oxidation occurred after an induction period, while at 950 %C2%B0C oxidation occurred without an induction period. At oxidation temperatures between 1050 and 1150 %C2%B0C rapid passivation of the surface of the aluminum foil occurred, while at 1250 %C2%B0C and above, an initial rapid mass increase was observed, followed by a more gradual increase in mass. The initial rapid increase was accompanied by a significant exotherm. Cross-sections of oxidized specimens were characterized by scanning electron microscopy (SEM); the observed alumina skin thicknesses correlated qualitatively with the observed mass increases.

Coker, Eric Nicholas

2013-10-01

157

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

158

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

NASA Astrophysics Data System (ADS)

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

Röder, P.; Baba, N.; Wiemhöfer, H.-D.

2014-02-01

159

Characterization of RDF properties through high pressure differential scanning calorimetry  

NASA Astrophysics Data System (ADS)

High Pressure Differential Scanning Calorimetry was employed to study the thermal analytical properties of refuse derived fuels (RDF). By comparison with studies on newsprint and polyethylene, four characteristic thermogram peaks are identified with the smoldering combustion of plastics, cellulosic materials and two types of char respectively. Similarities and differences between thermograms of refuse derived fuels and coal samples are noted. The variability of thermal analytical properties as a function of process parameters, sampling, and source was determined. Finally, data from pyrolytic studies using thermogravimetry as well as scanning calorimetry are presented.

Tsang, W.; Walker, J. A.

1982-02-01

160

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

161

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

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Frequencies for digital selective calling (DSC...SERVICES STATIONS IN THE MARITIME SERVICES Frequencies Radiotelegraphy § 80.359 Frequencies for digital selective calling...

2012-10-01

162

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

Microsoft Academic Search

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

M. Depenbrock

1988-01-01

163

NANO-SCALE CALORIMETRY OF ISOLATED POLYETHYLENE SINGLE CRYSTALS  

E-print Network

#12;NANO-SCALE CALORIMETRY OF ISOLATED POLYETHYLENE SINGLE CRYSTALS BY ALEX TAN KWAN B.S., Stanford) device, the nanocalorimeter, it was possible to investigate the melting of isolated polyethylene (PE, a simple Ni-foil calorimeter, to measure the heat capacity of a thin polyethylene film to verify

Allen, Leslie H.

164

Calorimetry 101 for Cold Fusion; Methods, Problems and Errors  

Microsoft Academic Search

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

Edmund Storms

165

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

166

Test in a beam of large-area Micromegas chambers for sampling calorimetry  

NASA Astrophysics Data System (ADS)

The application of Micromegas for sampling calorimetry puts specific constraints on the design and performance of this gaseous detector. In particular, uniform and linear response, low noise and stability against high ionisation density deposits are prerequisites for achieving good energy resolution. A Micromegas-based hadronic calorimeter was proposed for an application at a future linear collider experiment and three technologically advanced prototypes of 1×1 m2 were constructed. Their merits relative to the above-mentioned criteria are discussed on the basis of measurements performed at the CERN SPS test-beam facility.

Adloff, C.; Chefdeville, M.; Dalmaz, A.; Drancourt, C.; Gaglione, R.; Geffroy, N.; Jacquemier, J.; Karyotakis, Y.; Koletsou, I.; Peltier, F.; Samarati, J.; Vouters, G.

2014-11-01

167

Calorimetry in ZEUS: Lessons for the future  

SciTech Connect

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

Derrick, M.

1988-01-01

168

What does calorimetry and thermodynamics of living cells tell us?  

PubMed

This article presents and compares several thermodynamic methods for the quantitative interpretation of data from calorimetric measurements. Heat generation and absorption are universal features of microbial growth and product formation as well as of cell cultures from animals, plants and insects. The heat production rate reflects metabolic changes in real time and is measurable on-line. The detection limit of commercially available calorimetric instruments can be low enough to measure the heat of 100,000 aerobically growing bacteria or of 100 myocardial cells. Heat can be monitored in reaction vessels ranging from a few nanoliters up to many cubic meters. Most important the heat flux measurement does not interfere with the biological process under investigation. The practical advantages of calorimetry include the waiver of labeling and reactants. It is further possible to assemble the thermal transducer in a protected way that reduces aging and thereby signal drifts. Calorimetry works with optically opaque solutions. All of these advantages make calorimetry an interesting method for many applications in medicine, environmental sciences, ecology, biochemistry and biotechnology, just to mention a few. However, in many cases the heat signal is merely used to monitor biological processes but only rarely to quantitatively interpret the data. Therefore, a significant proportion of the information potential of calorimetry remains unutilized. To fill this information gap and to motivate the reader using the full information potential of calorimetry, various methods for quantitative data interpretations are presented, evaluated and compared with each other. Possible errors of interpretation and limitations of quantitative data analysis are also discussed. PMID:25461814

Maskow, Thomas; Paufler, Sven

2015-04-01

169

New detecting techniques for a future calorimetry  

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

170

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

171

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

172

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

173

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

PubMed

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

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

2008-01-01

174

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

175

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

176

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

177

The Philosophy and Feasibility of Dual Readout Calorimetry  

SciTech Connect

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

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

2006-10-27

178

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. PMID:23594763

2013-01-01

179

Helium droplet calorimetry of strongly bound species: carbon clusters from C? to C??.  

PubMed

Helium droplet beam methods are a versatile technique that can be used to assemble a wide variety of atomic and molecular clusters. In recent years, methods have been developed to utilize helium droplets as nano-calorimeters to measure the binding energies of weakly bound complexes assembled within the droplet. In the current investigation we extend the helium droplet calorimetry approach to the study of a very strongly bound system: carbon clusters which are bound by several eV per atom. We utilize laser heating of bulk carbon samples to dope the helium droplets with evaporated carbon species. Depending on the laser target, the vaporization plume is found to consist primarily of C3 alone or C2 and C3. These species are sequentially captured by the droplet and assembled into larger carbon clusters in a stepwise manner. The assembled C(n) clusters are detected via mass spectrometry of the doped droplets and the droplet sizes required to detect the various carbon clusters observed are used to estimate the reaction energies of the associated assembly pathways. The helium droplet data qualitatively reflect the trends in assembly energetics, but at first glance appear to yield energies that differ dramatically from theoretical values. Statistical modeling of the helium droplet calorimetry experiment reconciles the differences quantitatively. Our modeling also generates a calibration curve that relates the assembly/reaction energy and threshold mean droplet size over a range of energies from van der Waals interactions to chemical bonding, enabling helium droplet calorimetry methods to be applied quantitatively to a large number of systems. PMID:25273742

Lewis, William K; Harruff-Miller, Barbara A; Leatherman, Peter; Gord, Michael A; Bunker, Christopher E

2014-09-01

180

Helium droplet calorimetry of strongly bound species: Carbon clusters from C2 to C12  

NASA Astrophysics Data System (ADS)

Helium droplet beam methods are a versatile technique that can be used to assemble a wide variety of atomic and molecular clusters. In recent years, methods have been developed to utilize helium droplets as nano-calorimeters to measure the binding energies of weakly bound complexes assembled within the droplet. In the current investigation we extend the helium droplet calorimetry approach to the study of a very strongly bound system: carbon clusters which are bound by several eV per atom. We utilize laser heating of bulk carbon samples to dope the helium droplets with evaporated carbon species. Depending on the laser target, the vaporization plume is found to consist primarily of C3 alone or C2 and C3. These species are sequentially captured by the droplet and assembled into larger carbon clusters in a stepwise manner. The assembled Cn clusters are detected via mass spectrometry of the doped droplets and the droplet sizes required to detect the various carbon clusters observed are used to estimate the reaction energies of the associated assembly pathways. The helium droplet data qualitatively reflect the trends in assembly energetics, but at first glance appear to yield energies that differ dramatically from theoretical values. Statistical modeling of the helium droplet calorimetry experiment reconciles the differences quantitatively. Our modeling also generates a calibration curve that relates the assembly/reaction energy and threshold mean droplet size over a range of energies from van der Waals interactions to chemical bonding, enabling helium droplet calorimetry methods to be applied quantitatively to a large number of systems.

Lewis, William K.; Harruff-Miller, Barbara A.; Leatherman, Peter; Gord, Michael A.; Bunker, Christopher E.

2014-09-01

181

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

182

Effects of heating at neutral and acid pH on the structure of beta-lactoglobulin A revealed by differential scanning calorimetry and circular dichroism spectroscopy.  

PubMed

The structural change of beta-lactoglobulin A (betaLG A) on heating was measured at pH 3.0 and 7.5 with UV absorption difference spectra, differential scanning calorimetry (DSC), and circular dichroism (CD). At pH 3.0, betaLG A showed a reversible structural change by heating at 80 degrees C, while an irreversible change was observed and molecular aggregates of betaLG were formed by heating at 95 degrees C. DSC analysis of betaLG A gave endothermic peaks at 75 degrees C and 90 degrees C at pH 7.5, and 90 degrees C at pH 3.0. At pH 7.5, betaLG A modified with N-ethylmaleimide (NEM-betaLG A) gave two endothermic peaks: at 72 degrees C and 90 degrees C. CD spectra of betaLG A heated at various temperatures and pHs were measured and the spectra at pH 3.0 and 7.5 were not changed by heating to 95 degrees C and 80 degrees C, respectively. Unheated NEM-betaLG A gave a spectrum similar to that of heated betaLG A, suggesting that the secondary structure was changed by NEM treatment. PMID:16545525

Wada, Ritsuko; Fujita, Yuki; Kitabatake, Naofumi

2006-06-01

183

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

NASA Astrophysics Data System (ADS)

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

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

2003-07-01

184

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

NASA Astrophysics Data System (ADS)

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

Souri, Dariush

2015-01-01

185

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

NASA Astrophysics Data System (ADS)

The XVIth International Conference on Calorimetry in High Energy Physics - CALOR 2014 - was held in Giessen, Germany from 6-11 April 2014 at the Science Campus of the University. It was hosted by the Justus-Liebig-University and the HIC for FAIR Helmholtz International Center. The series of conferences on calorimetry were started in 1990 at Fermilab and are focusing primarily on operating and future calorimeter systems within the Hadron and High-Energy Physics community without neglecting the impact on other fields such as Astrophysics or Medical Imaging. Confirmed by the impressive list of over 70 oral presentations, 5 posters and over 100 attendees, the field of calorimetry appears alive and attractive. The present volume contains the written contributions of almost all presentations which can be found at http://calor2014.de. Time slots of 15 or 30 minutes including discussion were allocated. The conference was accompanied by a small exhibition of several industrial companies related to the field. The day before the opening of the scientific program, Richard Wigmans gave an excellent and vivid tutorial on basic aspects on calorimetry meant as an introduction for students and conference attendees new in the field. The opening ceremony was used to give an impression of the present and future status and the scientific program of the new FAIR facility nearby at Darmstadt presented by Klaus Peters from GSI. The conference program of the first day was dedicated to the performance and required future upgrade of the LHC experiments, dominated by ATLAS, CMS and LHCb. The program of the next day contained specific aspects on electronics and readout as well as calorimetry in outer space. Several contributions discussed in detail new concepts for hadron calorimeters within the CALICE collaboration completed by a session on sampling calorimeters. The next sections were dedicated to operating and future calorimeters at various laboratories and covering a wide range of projectiles and beam energies, such as ELSA at Bonn, BELLE2, BESIII or future projects at JLab, FAIR or RHIC. The last group of contributions was focusing on new concepts including new detector materials or techniques taking into account the general demand on radiation hardness. Damage caused by a large fluence of hadrons appears to become the limiting factor for the detector performance in future collider experiments. The scientific program was completed by a single contribution on applications in medical imaging. Marcella Diemoz gave a personal conference summary underlining again the high quality of the presentations, lively discussions and the wide range of the physics program and the related detector systems. The significant support by the Justus-Liebig-University, HIC for FAIR and sponsoring industrial partners allowed to keep the overall costs low and to support the participation of students and young scientists. I personally would like to thank the session chairs, the local organizing committee, the secretaries, technicians and students of the institute for the smooth operation of the conference. Finally, I would like to express my appreciation to all participants who made the conference successful by their high level contributions and discussion distributing their ideas and experiences. Rainer W Novotny Chair of the Conference

Novotny, Rainer W.

2015-02-01

186

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

PubMed

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

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

2014-09-01

187

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

188

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

NASA Astrophysics Data System (ADS)

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

Schetelat, Pascal; Etay, Jacqueline

2011-07-01

189

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

190

DMSO-Induced Dehydration of DPPC Membranes Studied by X-ray Diffraction, Small-Angle Neutron Scattering, and Calorimetry  

E-print Network

The influence of dimethyl sulfoxide (DMSO) on membrane thickness, multilamellar repeat distance, and phase transitions of 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) was investigated by X-ray diffraction and small-angle neutron scattering (SANS). The differential scanning calorimetry (DSC) study of water freezing and ice melting was performed in the ternary DPPC /DMSO /water and binary DMSO /water systems. The methods applied demonstrated the differences in membrane structure in three sub-regions of the DMSO mole fraction (X_dmso): from 0.0 to 0.3 for the first, from 0.3 to 0.8 for the second, and from 0.9 to 1.0 for the third sub-region. The thickness of the intermembrane solvent at T =20C decreases from 14.4 +/- 1.8 A at X_dmso =0.0 to 7.8 +/- 1.8 A at X_dmso =0.1. The data were used to determine the number of free water molecules in the intermembrane space in the presence of DMSO. The results for 0.0 dmso DMSO-induced dehydration of the intermembrane space.

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

2001-08-12

191

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

E-print Network

REDES DE COMPUTADORES © UFPB / CCT / DSC / PSN, 2001 * Parte 4: Estudo de Caso - UFPB * Pág. 1 3.2 REDE DA UNIVERSIDADE FEDERAL DA PARAÍBA - UFPB-NET PREMISSAS BÁSICAS ! As redes de comunicação de dados a cargo de cada departamento/núcleo/setor a organização de sua rede interna; definição de uma espinha

Cirne, Walfredo

192

REDES DE COMPUTADORES UFPB / CCT / DSC / PSN, 2001 * Parte 3: TCP/IP -Introduo * Pg. 1  

E-print Network

REDES DE COMPUTADORES © UFPB / CCT / DSC / PSN, 2001 * Parte 3: TCP/IP - Introdução * Pág. 1 uma rede experimental de comutação de pacotes ­ ARPANET ­ que deveria prover: robustez; confiabilidade de um protocolo para interconexão de redes; ! 1980, TCP/IP torna-se padrão na ARPANET; ! 1983, TCP

Cirne, Walfredo

193

REDES DE COMPUTADORES UFPB / CCT / DSC / PSN, 2001 * Parte 2: Arquitetura -Camada de Aplicao * Pg. 1  

E-print Network

REDES DE COMPUTADORES © UFPB / CCT / DSC / PSN, 2001 * Parte 2: Arquitetura - Camada de Aplicação * Pág. 1 2.5 A CAMADA DE APLICAÇÃO ! A camada de aplicação fornece os serviços "reais" de rede para os sistema de computação seguro. Você meramente tem de desconectar seu sistema de qualquer rede externa, e

Cirne, Walfredo

194

REDES DE COMPUTADORES UFPB / CCT / DSC / PSN, 2001 * Parte 2: Arquitetura -Camada de Transporte * Pg. 1  

E-print Network

REDES DE COMPUTADORES © UFPB / CCT / DSC / PSN, 2001 * Parte 2: Arquitetura - Camada de Transporte, independente da (ou das) rede física existente. ! O hardware e software no nível de transporte que desempenha, em um processo separado ou mesmo na placa de interface de rede. Entidade de Transporte Nível de

Cirne, Walfredo

195

REDES DE COMPUTADORES UFPB / CCT / DSC / PSN, 2001 * Parte 2: Arquitetura -Camada de Enlace * Pg. 1  

E-print Network

REDES DE COMPUTADORES © UFPB / CCT / DSC / PSN, 2001 * Parte 2: Arquitetura - Camada de Enlace definida para a camada de rede; Organiza os dados recebidos da camada de rede em quadros (frames) a serem transmitidos na rede física (e vice-versa); Trata erros de transmissão; e Realiza controle de fluxo para

Cirne, Walfredo

196

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

197

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

Microsoft Academic Search

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

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

2002-01-01

198

Photo-DSC cure kinetics of vinyl ester resins II: influence of diluent concentration  

Microsoft Academic Search

The photopolymerization kinetics of two commercial vinyl ester resins (VERs) and a model VER photoinitiated by the camphorquinone\\/amine photoinitiator system were monitored using isothermal DSC. A decrease in styrene concentration in model VERs was found to raise the rate of photopolymerization. In contrast, when the styrene was replaced by a monomethacrylate diluent, the photopolymerization rate passed through a maximum near

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

2003-01-01

199

Investigation of the exothermicity of radical induced photopolymerization by RTFTIR spectroscopy and photoDSC  

Microsoft Academic Search

The exothermicity of the radical photopolymerization of coatings was investigated for various acrylic monomers bearing different functionalities. The maximum conversion ratio and the rates of polymerization were monitored as a function of time by RT-FTIR spectroscopy and photo-DSC. The change in temperature due to the polymerization reaction was probed by using a polypropylene film as internal temperature probe and calorimetric

Milèna De Brito; François Courtecuisse; Xavier Allonas

200

A structural study of DPP-based sensitizers for DSC applications.  

PubMed

Four D-?-A sensitizers comprising a thienyl-diketopyrrolopyrrole (ThDPP) bridge were synthesized and tested in iodide/triiodide liquid electrolyte DSC devices. The dye series was strategically designed to develop a structure-property relationship. The best performing sensitizer utilized a phenyl-based anchor and triphenylamine donor (? = 5.03%). PMID:23019568

Holcombe, Thomas W; Yum, Jun-Ho; Yoon, Junghyun; Gao, Peng; Marszalek, Magdalena; Di Censo, Davide; Rakstys, Kasparas; Nazeeruddin, Md K; Graetzel, Michael

2012-11-11

201

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

E-print Network

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

Mavroidis, Constantinos

202

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

E-print Network

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

Paris-Sud XI, Université de

203

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

PubMed

Ethidium bromide displacement assay by fluorescence is frequently used as a diagnostic tool to identify the intercalation ability of DNA binding small molecules. Here we have demonstrated that the method has pitfalls. We have employed fluorescence, absorbance and label free technique such as isothermal titration calorimetry to probe the limitations. Ethidium bromide, a non-specific intercalator, netropsin, a (A-T) specific minor groove binder, and sanguinarine, a (G-C) specific intercalator, have been used in our experiments to study the association of a ligand with DNA in presence of a competing ligand. Here we have shown that netropsin quenches the fluorescence intensity of an equilibrium mixture of ethidium bromide - calf thymus DNA via displacement of ethidium bromide. Isothermal titration calorimetry results question the accepted interpretation of the observed decrease in fluorescence of bound ethidium bromide in terms of competitive binding of two ligands to DNA. Furthermore, isothermal titration calorimetry experiments and absorbance measurements indicate that the fluorescence change might be due to formation of ternary complex and not displacement of one ligand by another. PMID:23494169

Banerjee, Amrita; Singh, Jasdeep; Dasgupta, Dipak

2013-07-01

204

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

PubMed

Voltage-gated sodium channels (Nav channels) are critical for electrical signaling in the nervous system and are the primary targets of the insecticides DDT and pyrethroids. In Drosophila melanogaster, besides the canonical Nav channel, Para (also called DmNav), there is a sodium channel-like cation channel called DSC1 (Drosophila sodium channel 1). Temperature-sensitive paralytic mutations in DmNav (para(ts)) confer resistance to DDT and pyrethroids, whereas DSC1 knockout flies exhibit enhanced sensitivity to pyrethroids. To further define the roles and interaction of DmNav and DSC1 channels in DDT and pyrethroid neurotoxicology, we generated a DmNav/DSC1 double mutant line by introducing a para(ts1) allele (carrying the I265N mutation) into a DSC1 knockout line. We confirmed that the I265N mutation reduced the sensitivity to two pyrethroids, permethrin and deltamethrin of a DmNav variant expressed in Xenopus oocytes. Computer modeling predicts that the I265N mutation confers pyrethroid resistance by allosterically altering the second pyrethroid receptor site on the DmNav channel. Furthermore, we found that I265N-mediated pyrethroid resistance in para(ts1) mutant flies was almost completely abolished in para(ts1);DSC1(-/-) double mutant flies. Unexpectedly, however, the DSC1 knockout flies were less sensitive to DDT, compared to the control flies (w(1118A)), and the para(ts1);DSC1(-/-) double mutant flies were even more resistant to DDT compared to the DSC1 knockout or para(ts1) mutant. Our findings revealed distinct roles of the DmNav and DSC1 channels in the neurotoxicology of DDT vs. pyrethroids and implicate the exciting possibility of using DSC1 channel blockers or modifiers in the management of pyrethroid resistance. PMID:25687544

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

2015-03-01

205

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

206

Calorimetry exchange program. Quarterly data report, 1st 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

207

Isothermal Titration Calorimetry of Membrane Proteins – Progress and Challenges  

PubMed Central

Summary Integral membrane proteins, including G protein-coupled receptors (GPCR) and ion channels, mediate diverse biological functions that are crucial to all aspects of life. The knowledge of the molecular mechanisms, and in particular, the thermodynamic basis of the binding interactions of the extracellular ligands and intracellular effector proteins is essential to understand the workings of these remarkable nanomachines. In this review, we describe how isothermal titration calorimetry (ITC) can be effectively used to gain valuable insights into the thermodynamic signatures (enthalpy, entropy, affinity, and stoichiometry), which would be most useful for drug discovery studies, considering that more than 30% of the current drugs target membrane proteins. PMID:23747362

Rajarathnam, Krishna; Rösgen, Jörg

2013-01-01

208

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

E-print Network

REDES DE COMPUTADORES © UFPB / CCT / DSC / PSN, 2001 * Parte 4: Estudo de Caso - RPP/RNP * Pág. 1 3.3 REDE NACIONAL DE PESQUISA - RNP REDE PARAIBANA DE PESQUISA - RPP INTERNET ! Maior rede mundial de. REDES DE COMPUTADORES © UFPB / CCT / DSC / PSN, 2001 * Parte 4: Estudo de Caso - RPP/RNP * Pág. 2 ! Sua

Cirne, Walfredo

209

Electrical conductivity, differential scanning calorimetry, X-ray diffraction, and 7Li nuclear magnetic resonance studies of n-C x H(2x+1)OSO3Li (x = 12, 14, 16, 18, and 20)  

NASA Astrophysics Data System (ADS)

Electrical conductivity (?), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) measurements of n-C x H (2x+1) OSO 3Li (x= 12, 14, 16, 18, and 20) crystals were performed as a function of temperature. In addition, ?, DSC, and XRD observations of n-C x H (2x+1) OSO 3Na and n-C x H (2x+1) OSO 3K (x= 12, 14, 16, 18, and 20) crystals were carried out for comparison. DSC results of the salts revealed several solid-solid phase transitions with large entropy changes (?S). For n-C 18 H 37 OSO 3Li and n-C 20 H 41 OSO 3Li salts, each melting point produced a small ?S mp value compared with the total entropy change in the solid phases (?S tr1+?S tr2). Additionally, Li + ion diffusion was detected in the highest temperature solid phases. For K salts, larger ? values were detected for potassium alkylsulfates compared with those reported for alkyl carboxylate. 7Li NMR spectra of n-C 18 H 37 OSO 3Li crystals recorded in the low-temperature phase showed large asymmetry parameters, suggesting the Li + ions are localized at asymmetric sites in the crystals.

Hirakawa, Satoru; Morimoto, Yoshiaki; Honda, Hisashi

2014-11-01

210

DSC and FTIR studies on Gellan and Polyvinyl alcohol (PVA) blend films  

Microsoft Academic Search

Homopolymer films of Gellan and polyvinyl alcohol (PVA) and blended films were prepared by a solution casting method from a polymer solution in water of Gellan and PVA using glycerol as plasticizer. The films were studied for thermal characteristics by differential scanning calorimetry, for intermolecular interactions by Fourier transform infrared spectroscopy and for the mechanical properties of tear strength, tensile

S. R Sudhamani; M. S Prasad; K Udaya Sankar

2003-01-01

211

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

PubMed

The membrane-bound sterol regulatory element-binding protein (SREBP) transcription factors regulate lipogenesis in mammalian cells and are activated through sequential cleavage by the Golgi-localized Site-1 and Site-2 proteases. The mechanism of fission yeast SREBP cleavage is less well defined and, in contrast, requires the Golgi-localized Dsc E3 ligase complex. The Dsc E3 ligase consists of five integral membrane subunits, Dsc1 through Dsc5, and resembles membrane E3 ligases that function in endoplasmic reticulum-associated degradation. Using immunoprecipitation assays and blue native electrophoresis, we determined the subunit architecture for the complex of Dsc1 through Dsc5, showing that the Dsc proteins form subcomplexes and display defined connectivity. Dsc2 is a rhomboid pseudoprotease family member homologous to mammalian UBAC2 and a central component of the Dsc E3 ligase. We identified conservation in the architecture of the Dsc E3 ligase and the multisubunit E3 ligase gp78 in mammals. Specifically, Dsc1-Dsc2-Dsc5 forms a complex resembling gp78-UBAC2-UBXD8. Further characterization of Dsc2 revealed that its C-terminal UBA domain can bind to ubiquitin chains but that the Dsc2 UBA domain is not essential for yeast SREBP cleavage. Based on the ability of rhomboid superfamily members to bind transmembrane proteins, we speculate that Dsc2 functions in SREBP recognition and binding. Homologs of Dsc1 through Dsc4 are required for SREBP cleavage and virulence in the human opportunistic pathogen Aspergillus fumigatus. Thus, these studies advance our organizational understanding of multisubunit E3 ligases involved in endoplasmic reticulum-associated degradation and fungal pathogenesis. PMID:23760507

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

2013-07-19

212

The Pandora Software Development Kit for Particle Flow Calorimetry  

NASA Astrophysics Data System (ADS)

Pandora is a robust and efficient framework for developing and running pattern-recognition algorithms. It was designed to perform particle flow calorimetry, which requires many complex pattern-recognition techniques to reconstruct the paths of individual particles through fine granularity detectors. The Pandora C++ software development kit (SDK) consists of a single library and a number of carefully designed application programming interfaces (APIs). A client application can use the Pandora APIs to pass details of tracks and hits/cells to the Pandora framework, which then creates and manages named lists of self-describing objects. These objects can be accessed by Pandora algorithms, which perform the pattern-recognition reconstruction. Development with the Pandora SDK promotes the creation of small, re-usable algorithms containing just the kernel of a specific operation. The algorithms are configured via XML and can be nested to perform complex reconstruction tasks. As the algorithms only access the Pandora objects in a controlled manner, via the APIs, the framework can perform most book-keeping and memory-management operations. The Pandora SDK has been fully exploited in the implementation of PandoraPFA, which uses over 60 algorithms to provide the state of the art in particle flow calorimetry for ILC and CLIC.

Marshall, J. S.; Thomson, M. A.

2012-12-01

213

Phase behavior of polyelectrolyte multilayer investigated by thin film calorimetry  

NASA Astrophysics Data System (ADS)

Polyelectrolyte multilayer can be easily assembled using spraying or dipping of the different polyelectrolytes [1]. The thickness of the produced layers (nanometer range) is well controlled by the preparation conditions. Only a few methods are available for dynamic investigations, as afm for mechanical properties [2]. AC-chip calorimetry is used as a very sensitive tool for calorimetric investigations of such thin films as demonstrated for thin polymeric films [3]. To investigate the phase behavior of polyelectrolytes the humidity is used as a new parameter in addition to temperature for calorimetry. First measurements with the modified calorimeter for the PSS/PDADMAC polyelectrolyte multilayer system are shown. Further extensions of the calorimeter for better understanding of the phase behavior are discussed. [1] Decher, G. and J.D. Hong, Phys. Chem. Chem. Phys., 1991. 95(11): 1430. [2] Mueller, R., et al. Macromolecules, 2005. 38(23): 9766. [3] Huth, H., Minakov, A. A., Schick, C., J. Polym. Sci. B Polym. Phys. 2006 44: 2996.

Huth, H.; Mueller, R.; Fery, A.; Schick, C.

2008-03-01

214

Dynamic behavior of polyelectrolyte multilayer investigated by thin film calorimetry.  

NASA Astrophysics Data System (ADS)

Polyelectrolyte multilayer can be easily assembled using spraying or dipping of the different polyelectrolytes [1]. The thickness of the produced layers (nanometer range) is well controlled by the preparation conditions. Only a few methods are available for dynamic investigations, as afm for mechanical properties [2]. AC-chip calorimetry is used as a very sensitive tool for calorimetric investigations of such thin films as demonstrated for thin polymeric films in a wide frequency range [3]. To investigate the dynamic behavior of polyelectrolytes the humidity is used as a new parameter in addition to temperature for calorimetry. First measurements with the modified calorimeter for the PSS/PDADMAC polyelectrolyte multilayer system are shown. Further extensions of the calorimeter for better understanding of the phase behavior are discussed. [1] Decher, G. and J.D. Hong, Phys. Chem. Chem. Phys., 1991. 95(11): 1430. [2] Mueller, R., et al. Macromolecules, 2005. 38(23): 9766. [3] Huth, H., Minakov, A. A., Schick, C., J. Polym. Sci. B Polym. Phys. 2006 44: 2996.

Huth, H.; Mueller, R.; Fery, A.; Schick, C.

2009-03-01

215

FLUKA studies of hadron-irradiated scintillating crystals for calorimetry at the High-Luminosity LHC  

NASA Astrophysics Data System (ADS)

Calorimetry at the High-Luminosity LHC (HL-LHC) will be performed in a harsh radiation environment with high hadron fluences. The upgraded CMS electromagnetic calorimeter design and suitable scintillating materials are a focus of current research. In this paper, first results using the Monte Carlo simulation program FLUKA are compared to measurements performed with proton-irradiated LYSO, YSO and cerium fluoride crystals. Based on these results, an extrapolation to the behavior of an electromagnetic sampling calorimeter, using one of the inorganic scintillators above as an active medium, is performed for the upgraded CMS experiment at the HL-LHC. Characteristic parameters such as the induced ambient dose, fluence spectra for different particle types and the residual nuclei are studied, and the suitability of these materials for a future calorimeter is surveyed. Particular attention is given to the creation of isotopes in an LYSO-tungsten calorimeter that might contribute a prohibitive background to the measured signal.

Quittnat, Milena; CMS collaboration

2015-02-01

216

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

217

Critical phenomenon during photoinitiated gelation at different temperatures: A Photo-DSC study  

Microsoft Academic Search

The behaviour of photoinitiated radical polymerization of an 80wt% epoxy diacrylate (EA) and 20wt% tripropyleneglycoldiacrylate (TPGDA) mixture with 2-mercaptothioxanthone (TX-SH) photoinitiator was studied at different temperatures by using photo-differential scanning calorimetric (Photo-DSC) technique. All photopolymerization reactions were carried out under the same conditions. It was observed that all conversion curves during gelation at different temperatures present nice sigmoidal behaviour which

Zekeriya Do?ruyol; Nergis Arsu; Sevnur Keskin Do?ruyol; Önder Pekcan

2011-01-01

218

Influence of the molecular mass on the segmental relaxation times of polystyrene determined by DSC  

Microsoft Academic Search

The segmental dynamics of narrow fractions (Mw\\/Mn ?1.05) of polystyrene with molecular masses ranging from 4000 to 600000 has been characterised by DSC. The samples\\u000a were subjected to different thermal histories previously to the recorded heating scans including cooling from equilibrium\\u000a at different cooling rates and annealing at different temperatures for different times. The fragility parameter m=[?log?\\/?\\u000a (Tg\\/T)]Tggwas determined from

F. Hernández Sánchez; J. M. Meseguer Due?as; J. L. Gómez Ribelles

2003-01-01

219

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

220

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

PubMed Central

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

Kaiyala, Karl J.; Ramsay, Douglas S.

2012-01-01

221

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

NASA Astrophysics Data System (ADS)

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

Okamoto, Kiyoshi; Hagura, Yoshio; Suzuki, Kanichi

222

Fast Scanning Calorimetry Studies of Supercooled Liquids and Glasses  

NASA Astrophysics Data System (ADS)

This dissertation is a compilation of research results of extensive Fast Scanning Calorimetry studies of two non-crystalline materials: Toluene and Water. Motivation for fundamental studies of non-crystalline phases, a brief overview of glassy materials and concepts and definitions related to them is provided in Chapter 1. Chapter 2 provides fundamentals and details of experimental apparata, experimental protocol and calibration procedure. Chapter 3 & 4 provides extensive studies of stable non-crystalline toluene films of micrometer and nanometer thicknesses grown by vapor deposition at distinct deposition rates and temperatures and probed by Fast Scanning Calorimetry. Fast scanning calorimetry is shown to be extremely sensitive to the structure of the vapor-deposited phase and was used to characterize simultaneously its kinetic stability and its thermodynamic properties. According to our analysis, transformation of vapor -deposited samples of toluene during heating with rates in excess 100,000 K/s follows the zero-order kinetics. The transformation rate correlates strongly with the initial enthalpy of the sample, which increases with the deposition rate according to sub-linear law. Analysis of the transformation kinetics of vapor deposited toluene films of various thicknesses reveal a sudden increase in the transformation rate for films thinner than 250 nm. The change in kinetics correlates with the surface roughness scale of the substrate, which is interpreted as evidence for kinetic anisotropy of the samples. We also show that out-of-equilibrium relaxation kinetics and possibly the enthalpy of vapor-deposited (VD) films of toluene are distinct from those of ordinary supercooled (OS) phase even when the deposition takes place at temperatures above the glass softening (Tg). The implications of these findings for the formation mechanism and structure of vapor deposited stable glasses are discussed. Chapter 5 and 6 provide detailed Fast Scanning Calorimetry studies of amorphous solid water in bulk and confining geometry (ultrathin films and nano-aggregates). Bulk-like water samples were prepared by vapor-deposition on the surface of a tungsten filament near 140 K where vapor-deposition results in low enthalpy glassy water films. The vapor deposition approach was also used to grow nano-aggregates (2- 20 nm thick) and multiple ultrathin (approximately 50 nm thick) water films alternated with benzene and methanoic films of similar dimensions. When heated from cryogenic temperatures, the ultrathin water films underwent a well manifested glass softening transition at temperatures 20 degrees below the onset of crystallization. The thermograms of nano-aggregates of ASW films show two endotherms at 40 and 10 K below the onset temperatures of crystallization. However, no such transition was observed in bulk-like water samples prior to their crystallization. These results indicate that water in confined geometry demonstrates glass softening dynamics which are dramatically distinct from those of the bulk phase. We attribute these differences to water's interfacial glass transition which occurs at temperatures tens of degrees lower than that in the bulk. Implications of these finding for past studies of glass softening dynamics in various glassy water samples are discussed in chapter 5 and 6.

Bhattacharya, Deepanjan

223

Isothermal titration calorimetry of ion-coupled membrane transporters.  

PubMed

Binding of ligands, ranging from proteins to ions, to membrane proteins is associated with absorption or release of heat that can be detected by isothermal titration calorimetry (ITC). Such measurements not only provide binding affinities but also afford direct access to thermodynamic parameters of binding - enthalpy, entropy and heat capacity. These parameters can be interpreted in a structural context, allow discrimination between different binding mechanisms and guide drug design. In this review, we introduce advantages and limitations of ITC as a methodology to study molecular interactions of membrane proteins. We further describe case studies where ITC was used to analyze thermodynamic linkage between ions and substrates in ion-coupled transporters. Similar type of linkage analysis will likely be applicable to a wide range of transporters, channels, and receptors. PMID:25676707

Boudker, Olga; Oh, SeCheol

2015-04-01

224

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

225

ROC chips for imaging calorimetry at the International Linear Collider  

NASA Astrophysics Data System (ADS)

Imaging calorimetry at the International Linear Collider requires highly granular and innovative detectors. Technological prototypes have been built and tested under the CALICE collaboration framework and FP6 EUDET, FP7 AIDA European programs. These prototypes are readout by multi-channel chips named SKIROC2, SPIROC2 and HARDROC2, designed by the IN2P3 OMEGA group in AMS SiGe 350 nm technology. In this presentation, the ASIC architectures and test results on test bench and at system level will be described as well as first results of test bench measurements performed on HARDROC3, which is the first of the ``3rd generation'' chip to be submitted and where the 64 channels are handled independently to perform zero suppress on chip.

Callier, S.; Cizel, J.-B.; Dulucq, F.; de La Taille, C.; Martin-Chassard, G.; Seguin-Moreau, N.

2014-02-01

226

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

227

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

228

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

Microsoft Academic Search

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

Peggy Walter; Paul Cornillon

2002-01-01

229

Monitoring of an RNA Multistep Folding Pathway by Isothermal Titration Calorimetry  

E-print Network

Monitoring of an RNA Multistep Folding Pathway by Isothermal Titration Calorimetry Ce´dric Reymond Sherbrooke, Sherbrooke, Que´bec, Canada ABSTRACT Isothermal titration calorimetry was used to monitor.1 pseudoknot is the limiting step of the molecular mechanism. Last, as illustrated here, isothermal titration

Perreault, Jean-Pierre

230

Photo-DSC I: A new tool to study the semi-crystalline polymer accelerated photo-ageing  

Microsoft Academic Search

Photo-DSC was used, to study, in situ, the photo-ageing of polycyclo-octene which is a semi-crystalline elastomer. The ‘crystallizability’, which is the ability of the polymer to crystallize, was tightly dependent on the exposure time and was used to follow the photo-ageing.The irradiation system of photo-DSC was also compared with a usual accelerating device and no difference was detected in the

M. Morel; J. Lacoste; M. Baba

2005-01-01

231

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

PubMed

This study proposes an automatic method for identification and quantification of different tissue components: the non-enhanced infiltrative tumor, vasogenic edema and enhanced tumor areas, at the subject level, in patients with glioblastoma (GB) based on dynamic contrast enhancement (DCE) and dynamic susceptibility contrast (DSC) MRI. Nineteen MR data sets, obtained from 12 patients with GB, were included. Seven patients were scanned before and 8 weeks following bevacizumab initiation. Segmentation of the tumor area was performed based on the temporal data of DCE and DSC at the group-level using k-means algorithm, and further at the subject-level using support vector machines algorithm. The obtained components were associated to different tissues types based on their temporal characteristics, calculated perfusion and permeability values and MR-spectroscopy. The method enabled the segmentation of the tumor area into the enhancing permeable component; the non-enhancing hypoperfused component, associated with vasogenic edema; and the non-enhancing hyperperfused component, associated with infiltrative tumor. Good agreement was obtained between the group-level, unsupervised and subject-level, supervised classification results, with significant correlation (r = 0.93, p < 0.001) and average symmetric root-mean-square surface distance of 2.5 ± 5.1 mm. Longitudinal changes in the volumes of the three components were assessed alongside therapy. Tumor area segmentation using DCE and DSC can be used to differentiate between vasogenic edema and infiltrative tumors in patients with GB, which is of major clinical importance in therapy response assessment. PMID:25370705

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

2015-01-01

232

Physical transformation of niclosamide solvates in pharmaceutical suspensions determined by DSC and TG analysis.  

PubMed

This study reports the preparation of four niclosamide solvates and the determination of the stability of the crystal forms in different suspension vehicles by DSC and TG analysis. Thermal analysis showed that the niclosamide solvates were extremely unstable in a PVP-vehicle and rapidly changed to monohydrated crystals. A suspension in propylene glycol was more stable and TG analysis showed that crystal transformation was less rapid. In this vehicle, the crystals transformed to the anhydrate, rather than the monohydrate, since the vehicle was non-aqueous. The TEG-hemisolvate was the most stable in suspension and offered the best possibility of commercial exploitation. PMID:15296091

de Villiers, M M; Mahlatji, M D; Malan, S F; van Tonder, E C; Liebenberg, W

2004-07-01

233

Effects of Pretreatments on the Structure of Palladium-Containing Amorphous Alloys Followed by DSC  

Microsoft Academic Search

Amorphous PdZr, PdCuZr and PdCuSi alloy ribbons and powders are characterized by DSC, XRD and XPS in the as-received state\\u000a and after treatments with oxygen, hydrogen or dilute hydrogen fluoride solution. Zr-containing alloys are shown to undergo\\u000a substantial structural changes resulting in palladium enrichment on their surface, whereas no apparent changes in the bulk\\u000a structure are found for PdCuSi. Catalytic

M. Varga; G. Mulas; G. Cocco; Á. Molnár

1999-01-01

234

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

235

Fast Scanning Calorimetry studies of glassy and supercooled water  

NASA Astrophysics Data System (ADS)

Despite intense efforts, development of a comprehensive system of relationships between various condensed phases of water remains an illusive goal. The lack of consensus on the nature of supercooled and glassy water is due primarily to the lack of kinetic and thermodynamic data at temperatures from 150 to 235 K. Because supercooled water undergoes rapid crystallization near 235 K, application of standard experimental methods is virtually impossible. With the objective of gaining insights into properties of water, we have developed an experimental approach which relies on rapid (1000000 K/s) heating of micro- and mesoscopic aqueous samples prepared by vapor deposition in vacuum at cryogenic temperatures. Due to high heating rates, this Fast Scanning Calorimetry approach, makes it possible to bypass crystallization and to obtain new data on molecular kinetics and thermodynamics in glassy water in previously inaccessible temperature interval. We will report the results of our FSC studies and discuss their impact on fundamental and applied research areas where glassy and supercooled water plays significant role.

Bhattacharya, Deepanjan; Payne, Candace; Sadtchenko, Vlad

2012-02-01

236

High resolution optical calorimetry for synchrotron microbeam radiation therapy  

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

237

Application of isothermal titration calorimetry in bioinorganic chemistry.  

PubMed

The thermodynamics of metals ions binding to proteins and other biological molecules can be measured with isothermal titration calorimetry (ITC), which quantifies the binding enthalpy (?H°) and generates a binding isotherm. A fit of the isotherm provides the binding constant (K), thereby allowing the free energy (?G°) and ultimately the entropy (?S°) of binding to be determined. The temperature dependence of ?H° can then provide the change in heat capacity (?C (p)°) upon binding. However, ITC measurements of metal binding can be compromised by undesired reactions (e.g., precipitation, hydrolysis, and redox), and generally involve competing equilibria with the buffer and protons, which contribute to the experimental values (K (ITC), ?H (ITC)). Guidelines and factors that need to be considered for ITC measurements involving metal ions are outlined. A general analysis of the experimental ITC values that accounts for the contributions of metal-buffer speciation and proton competition and provides condition-independent thermodynamic values (K, ?H°) for metal binding is developed and validated. PMID:20725755

Grossoehme, Nicholas E; Spuches, Anne M; Wilcox, Dean E

2010-11-01

238

Combined Forward Calorimetry Option for Phase II CMS Endcap Upgrade  

NASA Astrophysics Data System (ADS)

Traditionally, EM and HAD compartments are thought to be separate and are often optimized individually. However, it is possible to optimize a robust and economical combined calorimeter system for myriad physics objectives. By employing event-by-event compensation afforded by the dual-readout technique, we have shown that excellent jet performance can be attained with a longitudinally un-segmented calorimeter that is calibrated only with electrons. In addition, the linear hadronic energy scale renders complex off-line correction schemes unnecessary. The proposed replacement of the CMS EE and HE calorimeters with a single Combined Forward Calorimeter (CFC) shows excellent jet performance complemented by good EM object detection. In this paper, we give brief snapshots on basic design criteria, timing characteristics of Cherenkov and scintillation pulses, trigger generation criteria and performance under high radiation fields. Although CMS has recently chosen different technologies for its endcap calorimetry in Phase II, the concepts developed here are likely to remain valuable for some time to come.

Akchurin, Nural

2015-02-01

239

Academic genealogy and direct calorimetry: a personal account.  

PubMed

Each of us as a scientist has an academic legacy that consists of our mentors and their mentors continuing back for many generations. Here, I describe two genealogies of my own: one through my PhD advisor, H. T. (Ted) Hammel, and the other through my postdoctoral mentor, Knut Schmidt-Nielsen. Each of these pathways includes distingished scientists who were all major figures in their day. The striking aspect, however, is that of the 14 individuals discussed, including myself, 10 individuals used the technique of direct calorimetry to study metabolic heat production in humans or other animals. Indeed, the patriarchs of my PhD genealogy, Antoine Lavoisier and Pierre Simon Laplace, were the inventors of this technique and the first to use it in animal studies. Brief summaries of the major accomplishments of each my scientific ancestors are given followed by a discussion of the variety of calorimeters and the scientific studies in which they were used. Finally, readers are encouraged to explore their own academic legacies as a way of honoring those who prepared the way for us. PMID:21652494

Jackson, Donald C

2011-06-01

240

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

241

Condensed complexes and the calorimetry of cholesterol-phospholipid bilayers.  

PubMed Central

A recent thermodynamic model describes a reversible reaction between cholesterol (C) and phospholipid (P) to form a condensed complex C(nq)P(np). Here q and p are relatively prime integers used to define the stoichiometric composition, and n is a measure of cooperativity. The present study applies this model to the scanning calorimetry of binary mixtures of cholesterol and saturated phosphatidylcholines, especially work by McElhaney and collaborators. These mixtures generally show two heat capacity peaks, a sharp peak and a broad peak. The sharp heat absorption is largely due to the chain melting transition of pure phospholipid. In the present work the broad heat absorption is attributed to the thermal dissociation of complexes. The best fits of the model to the data require the complex formation to be highly cooperative, with cooperativity n = 12. Detailed comparisons are made between model calculations and calorimetric data. A number of unusual features of the data arise naturally in the model. The principal discrepancy between the calculations and experimental results is a spurious calculated heat absorption peak. This discrepancy is related to the reported relative magnitudes of the integrated broad and sharp heat absorption curves. PMID:11606290

Anderson, T G; McConnell, H M

2001-01-01

242

High-resolution tritium calorimetry based on inertial temperature control  

NASA Astrophysics Data System (ADS)

A reassessment of the basic equation governing calorimetry shows the crucial importance of temperature stability in the calorimeter environment. Following the principles derived, we have developed a new temperature control method and demonstrated it in a prototype calorimeter over a wide dynamic range (5 ?W-2 W). Temperature control is achieved by using a metal block of high thermal inertia, surrounded by heat flow sensing thermopile arrays, which is embedded in an isothermal environment. Any temperature fluctuations in this environment are detected by the heat flow sensors and can be corrected by conventional feedback control. The advantage of this method is its high sensitivity to temperature changes: whereas conventional thermometers typically provide signals in the order of 1×10-3 V/K-1, a correctly selected combination of inertial mass and thermopile arrays can provide signals in the order of 1 V K-1, thus permitting an improvement of temperature control by three orders of magnitude. A commercially available thermoelectric calorimeter in an isothermal environment controlled by the new method permitted measurement of sample powers with ±10 ?W accuracy (long-term, short-term noise ˜±1 ?W), whereas in a conventional thermostatic bath (temperature stability ±0.02 K h-1) its resolution was limited to ±3 mW.

Hemmerich, J. L.; Serio, L.; Milverton, P.

1994-05-01

243

DSC and electrical conductivity studies of (Li1-xKx)2SO4 mixed crystals  

NASA Astrophysics Data System (ADS)

(Li1-Kx)2SO4 mixed crystals were prepared by the precipitation technique where x = 0.5, 0.7, 0.9 and 0.99. The phase transformations of the mixed crystals have been analyzed by the DSC technique. The DSC curves of (Li1-xKx)2SO4 mixed crystals reveal that as the potassium content increases the first high temperature phase of the intermediate LiKSO4 phase at T = 436°C disappears and a two- phase mixture of LiKSO4 and K2SO4 is found for x = 0.7 and 0.9E It is observed from the electrical conductivity measurements of (Li1-xKx)2SO4 mixed crystals that the electrical conductivity increases as the K2SO4 concentration increases with average activation energy of 1.04 eV. The enhancement in the electrical conductivity is primarily a result of the presence of two ionically conducting constituents and the formation of a diffuse space charge layer at the interface region between these two phases.

Ahmad, M. M.; Hefni, M. A.

244

TG and DSC studies of natural and artificial aging of polypropylene  

NASA Astrophysics Data System (ADS)

We study the evolution of thermal degradation of samples of polypropylene (PP), during their aging for two periods of 60 and 80 days. The study, using thermogravimetric analysis (TG) and differential scanning calorimetric (DSC) analyses, focused on two types of aging: the natural one under the impact of the solar environment and the artificial one which was carried out by exposing the sample to radiations of a 100 W commercial lamp. The comparative study of these two types of aging shows that the thermal degradation of the PP increases as a function of time of aging. Indeed, for a same duration, this thermal degradation is more important in the artificial aging case than it is in the natural one and is an increasing function of aging. The prolonged and continuous thermal effect produced by the lamp, in the case of the artificial aging, weakened the polymer and implies very important acceleration of the process of degradation. The results obtained during heating and cooling of the samples, using the DSC, show an evolution of the phase transition temperatures and the corresponding enthalpies of melting and crystallization.

Rjeb, M.; Labzour, A.; Rjeb, A.; Sayouri, S.; Claire, Y.; Périchaud, A.

2005-12-01

245

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

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

246

Thermal and electrical characterization of a micro-hotplate for calorimetry  

E-print Network

This thesis characterizes a micro-hotplate designed at Draper Laboratory. This hotplate will be integrated into a calorimetry system that measures the heat released or absorbed by a reaction. An analytical thermal model ...

Baliga, Radhika

2004-01-01

247

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

248

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

E-print Network

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

Amadi, Ovid Charles

2007-01-01

249

Thermaldecomposition of two synthetic glycosides by TG, DSC and simultaneous Py-GC-MSanalysis  

Microsoft Academic Search

To develop thermal stable flavor, two glycosidic\\u000a bound flavor precursors, geranyl-tetraacetyl-?-D-glucopyranoside\\u000a (GLY-A) and geranyl-?-D-glucopyranoside\\u000a (GLY-B) were synthesized by the modified Koenigs–Knorr reaction. The\\u000a thermal decomposition process and pyrolysis products of the two glycosides\\u000a were extensively investigated by thermogravimetry (TG), differential scanning\\u000a calorimeter (DSC) and on-line pyrolysis-gas chromatography mass spectroscopy\\u000a (Py-GC-MS). TG showed the T\\u000a p\\u000a of GLY-A and GLY-B were

W.-C. Xie; X.-H. Gu; Z.-C. Tan; J. Tang; G.-Y. Wang; C.-R. Luo; L.-X. Sun

2007-01-01

250

Characterization of the photopolymerization - kinetics of inorganic-organic nanocomposite materials by photo-DSC  

SciTech Connect

Organic-inorganic sol-gel derived composites with poly(methylmethacrylate) chains formed by polymerization already have shown their usefulness for many optical applications including embossing and holography technics to produce aspherical lenses, optical lattices and coatings for optical fibers. They can combine relatively low shrinkage with efficient photopolymerization and show overall properties being superior to those of pure methacrylate based polymers. The investigation of the kinetics of the radical polymerization however of methacrylate precursors containing hydrolyzable alkoxysilane groupings in sol-gel composite materials is more difficult due to the high inorganic crosslinking and the resulting high insolubility. For these reasons, Photo-DSC was assumed to be a useful method to investigate the kinetics of precursor systems, together with appropriate photoinitiators. The purpose of this work is to investigate the influence of the inorganic network formation on the kinetics of free radical polymerization reaction in methacryloxypropyltrimethoxysilane (MPTS) systems.

Becker, C.; Zahnhausen, M.; Krug, H.; Schmidt, H.

1995-12-31

251

Complex Heat Capacity of Lithium Borate Glasses Studied by Modulated DSC  

NASA Astrophysics Data System (ADS)

Complex heat capacity, Cp* = Cp' - iCp?, of lithium borate glasses Li2O?(1-x)B2O3 (x = 0.00 - 0.33) has been investigated by Modulated DSC (MDSC). We have successfully observed the frequency dependent Cp* 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; Matsui, Chihiro; Ike, Yuji; Kodama, Masao; Kojima, Seiji

2006-05-01

252

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

PubMed

Papaver somniferum L. is an important crop cultivated mostly for seed production. Poppy seeds have a high nutritive value and are used as a food and as a source of edible oil. This oil is a rich source of polyunsaturated fatty acids. It is well known that the unsaturated fatty acids easily undergo oxidation reactions, which lead to the reduction of shelf life, nutritional quality, development of unpleasant tastes and odors. The goal of this study was to develop the methodology for testing the stability of poppy seeds using non-isothermal DSC. For the treatment of the experimental data a method based on non-Arrhenian temperature function has been applied and the values the kinetic parameters have been obtained. In order to assess the durability of the commercial poppy seeds, the lengths of induction periods have been calculated. PMID:24360453

Cibulková, Zuzana; ?ertík, Milan; Dubaj, Tibor

2014-05-01

253

Development of GEM-Based Digital Hadron Calorimetry Using the SLAC KPiX Chip  

SciTech Connect

The development of Digital Hadron Calorimetry for the SiD detector Concept for the International Linear Collider is described. The jet energy requirements of the ILC physics program are discussed. The concept of GEM-based digital hadron calorimetry is presented, followed by a description of, and results from, prototype detectors. Plans are described for the construction of 1m{sup 2} GEM-DHCAL planes to be tested as part of a future calorimeter stack.

White, A.; /Texas U., Arlington /Washington U., Seattle /Unlisted /SLAC

2012-04-12

254

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

255

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. PMID:21964396

Aweda, Tolulope A.; Meares, Claude F.

2011-01-01

256

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

PubMed

In this research, the binding mechanism of Cu(2+) to bovine liver catalase (BLC) was studied by fluorescence spectroscopy, ultraviolet-visible (UV-vis) absorption spectroscopy, circular dichroism (CD) spectroscopy, isothermal titration calorimetry (ITC) and molecular docking methods. The cellar experiment was firstly carried out to investigate the inhibition effect of catalase. During the fluorescence quenching study, after correcting the inner filter effect (IFE), the fluorescence of BLC was found to be quenched by Cu(2+). The quenching mechanism was determined by fluorescence lifetime measurement, and was confirmed to be the dynamic mode. The secondary structure content of BLC was changed by the addition of Cu(2+), as revealed by UV-vis absorption and CD spectra, which further induces the decrease in BLC activity. Molecular simulation study indicates that Cu(2+) is located between two ?-sheets and two random coils of BLC near to the heme group, and interacts with His 74 and Ser 113 residues near a hydrophilic area. The decrease of ?-helix and the binding of His 74 are considered to be the major reason for the inhibition of BLC activity caused by Cu(2+). The ITC results indicate that the binding stoichiometry of Cu(2+) to catalase is 11.4. Moreover, the binding of Cu(2+) to BLC destroyed H-bonds, which was confirmed by the CD result. PMID:25618814

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

2015-02-01

257

CALOCUBE: an approach to high-granularity and homogenous calorimetry for space based detectors  

NASA Astrophysics Data System (ADS)

Future space experiments dedicated to the observation of high-energy gamma and cosmic rays will increasingly rely on a highly performing calorimetry apparatus, and their physics performance will be primarily determined by the geometrical dimensions and the energy resolution of the calorimeter deployed. Thus it is extremely important to optimize its geometrical acceptance, the granularity, and its absorption depth for the measurement of the particle energy with respect to the total mass of the apparatus which is the most important constraint for a space launch. The proposed design tries to satisfy these criteria while staying within a total mass budget of about 1.6 tons. Calocube is a homogeneous calorimeter instrumented with Cesium iodide (CsI) crystals, whose geometry is cubic and isotropic, so as to detect particles arriving from every direction in space, thus maximizing the acceptance; granularity is obtained by filling the cubic volume with small cubic CsI crystals. The total radiation length in any direction is more than adequate for optimal electromagnetic particle identification and energy measurement, whilst the interaction length is at least suficient to allow a precise reconstruction of hadronic showers. Optimal values for the size of the crystals and spacing among them have been studied. The design forms the basis of a three-year R&D activity which has been approved and financed by INFN. An overall description of the system, as well as results from preliminary tests on particle beams will be described.

Bongi, M.; Adriani, O.; Albergo, S.; Auditore, L.; Bagliesi, M. G.; Berti, E.; Bigongiari, G.; Boezio, M.; Bonechi, L.; Bonechi, S.; Bonvicini, V.; Bottai, S.; Brogi, P.; Carotenuto, G.; Cassese, A.; Castellini, G.; Cattaneo, P. W.; Cauz, D.; Cumani, P.; D'Alessandro, R.; Detti, S.; Fasoli, M.; Gregorio, A.; Lamberto, A.; Lenzi, P.; Maestro, P.; Marrocchesi, P. S.; Mezzasalma, A.; Miritello, M.; Mori, N.; Papini, P.; Pauletta, G.; Rappazzo, G. F.; Rappoldi, A.; Ricciarini, S.; Spillantini, P.; Starodubtsev, O.; Sulaj, A.; Tiberio, A.; Trifirò, A.; Trimarchi, M.; Vannuccini, E.; Vedda, A.; Zampa, G.; Zampa, N.; Zerbo, B.

2015-02-01

258

Misuse of thermodynamics in the interpretation of isothermal titration calorimetry data for ligand binding to proteins.  

PubMed

Isothermal titration calorimetry (ITC) has given a mass of data on the binding of small molecules to proteins and other biopolymers, with particular interest in drug binding to proteins chosen as therapeutic indicators. Interpretation of the enthalpy data usually follows an unsound protocol that uses thermodynamic relations in circumstances where they do not apply. Errors of interpretation include incomplete definitions of ligand binding and equilibrium constants and neglect of the non-ideality of the solutions under study, leading to unreliable estimates of standard free energies and entropies of binding. The mass of reported thermodynamic functions for ligand binding to proteins estimated from ITC enthalpies alone is consequently of uncertain thermodynamic significance and utility. ITC and related experiments to test the protocol assumptions are indicated. A thermodynamic procedure avoiding equilibrium constants or other reaction models and not requiring protein activities is given. The discussion draws attention to the fundamental but neglected relation between the thermodynamic activity and bioactivity of drugs and to the generally unknown thermodynamic status of ligand solutions, which for drugs relates directly to effective therapeutic dosimetry. PMID:25484232

Pethica, Brian A

2015-03-01

259

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

SciTech Connect

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

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

2007-05-25

260

Molecular interaction and localization of tocotrienol-rich fraction (TRF) within the matrices of lipid nanoparticles: evidence studies by Differential Scanning Calorimetry (DSC) and Proton Nuclear Magnetic Resonance spectroscopy ((1)H NMR).  

PubMed

Nanostructured lipid carriers (NLCs), made from mixtures of solid and liquid lipids, were postulated to have superior properties over solid lipid nanoparticles (SLNs). Nonetheless, the architecture of their inner cores remains elusive. The objective of this study was to elucidate the mode by which tocotrienol-rich fraction (TRF) is entrapped within NLCs and the impact of TRF interaction with solid lipids on the long-term stability of the nanoparticles. The mode of TRF localization was postulated from TEM image analysis and (1)H NMR signals' amplitude. The size, polydispersity, and fusion enthalpy were found to decrease with an increase in TRF loading, which implied a distortion in the crystallinity of the nanoparticles and the preferential entrapment of TRF within the cores of the NLCs. Nonetheless, (1)H NMR spectra of TRF-NLCs broadened as TRF load decreased from 100 to 10%, which was attributed to partial TRF mobility on the surface of the nanoparticles. This was confirmed by TEM images of NLCs at 50% TRF loads. These data led to the conclusion that NLCs have limited capacity to accommodate TRF with the excess being expelled to the surface of the nanoparticles. Such arrangement may have implication on future utility of the NLCs as drug delivery vehicles. PMID:20189780

Ali, Hazem; El-Sayed, Khalid; Sylvester, Paul W; Nazzal, Sami

2010-06-01

261

Picowatt Resolution Calorimetry for Micro and Nanoscale Energy Transport Studies  

NASA Astrophysics Data System (ADS)

Precise quantification of energy transport is key to obtaining insights into a wide range of phenomena across various disciplines including physics, chemistry, biology and engineering. This thesis describes technical advancements into heat-flow calorimetry which enable measurement of energy transport at micro and nanoscales with picowatt resolution. I have developed two types of microfabricated calorimeter devices and demonstrated single digit picowatt resolution at room temperature. Both devices incorporate two distinct features; an active area isolated by a thermal conductance (GTh) of less than 1 microW/K and a high resolution thermometer with temperature resolution (DeltaTres) in the micro kelvin regime. These features enable measurements of heat currents (q) with picowatt resolution (q= Th xDeltaTres). In the first device the active area is suspended via silicon nitride beams with excellent thermal isolation (~600 nW/K) and a bimaterial cantilever (BMC) thermometer with temperature resolution of ~6 microK. Taken together this design enabled calorimetric measurements with 4 pW resolution. In the second device, the BMC thermometry technique is replaced by a high-resolution resistance thermometry scheme. A detailed noise analysis of resistance thermometers, confirmed by experimental data, enabled me to correctly predict the resolution of different measurement schemes and propose techniques to achieve an order of magnitude improvement in the resolution of resistive thermometers. By incorporating resistance thermometers with temperature resolution of ~30 microK, combined with a thermal isolation of ~150 nW/K, I demonstrated an all-electrical calorimeter device with a resolution of ~ 5 pW. Finally, I used these calorimeters to study Near-Field Radiative Heat Transfer (NF-RHT). Using these devices, we studied--for the first time--the effect of film thickness on the NF-RHT between two dielectric surfaces. We showed that even a very thin film (~50 nm) of silicon dioxide deposited on a gold surface dramatically enhances NF-RHT between the coated surface and a second silica surface. Specifically, we find that the resulting heat fluxes are very similar to those between two bulk silicon dioxide surfaces when the gap size is reduced to be comparable to that of the film thickness. This interesting effect is understood on the basis of detailed computational analysis, which shows that the NF-RHT in gaps comparable to film thickness is completely dominated by the contributions from surface phonon-polaritons whose effective skin depth is comparable to the film thickness. These results are expected to hold true for various dielectric surfaces where heat transport is dominated by surface phonon-polaritons and have important implications for near-field based thermo photovoltaic devices and for near-field based thermal management.

Sadat, Seid H.

262

J. MACROMOL. SCI.--PHYSICS, B40(3&4), 517527 (2001) FTIR AND DSC STUDIES OF MECHANICALLY  

E-print Network

J. MACROMOL. SCI.--PHYSICS, B40(3&4), 517­527 (2001) FTIR AND DSC STUDIES OF MECHANICALLY DEFORMED of semicrystalline poly(vinylidene fluoride) (PVDF) in the - phase were studied by Fourier transform infrared (FTIR the understanding of the structural changes that occur in -PVDF during a mechanical deformation process. FTIR

263

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

264

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

265

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. PMID:23505382

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

2013-01-01

266

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

267

DSC and elastic moduli studies on tellurite-vanadate glasses containing antimony oxide  

NASA Astrophysics Data System (ADS)

xSb2O3-40TeO2-(60 - x) V2O5 glasses with 0 ? x ? 10 (in mol%) have been prepared by rapid- melt quenching method. DSC curves of these ternary glasses have been investigated. The glass transition properties that have been measured and reported in this paper, include the glass transition temperature (Tg), glass transition width (?Tg), heat capacity change at glass transition (?CP) and fragility (F). Thermal stability, Poisson's ratio, fragility and glass forming tendency of these glasses have been estimated, to determine relationship between chemical composition and the thermal stability or to interpret the structure of glass. In addition, Makishima and Makenzie's theory was applied for determination of Young's modulus, bulk modulus and shear modulus, indicating a strong relation between elastic properties and structure of glass. Generally, results of this work show that glass with x = 0 has the highest shear, bulk and Young's moduli which make it as suitable candidate for the manufacture of strong glass fibers in technological applications; but it should be mentioned that glass with x = 8 has higher handling temperature and super resistance against thermal attack.

Souri, D.

2011-11-01

268

Temperature Modulated DSC and Stiffness Threshold in Ge_xSe_1-x Glasses  

NASA Astrophysics Data System (ADS)

We have examined binary Ge_xSe_1-x glasses over a wide composition range 0 < x <0.34, using a TA Instruments Model 2920 MDSC. The glass transitions deduced from the heat flow increase monotonically with x or = 2(1+x), the average coordination number. The heat flow near Tg shows a rather striking threshold behavior (minimum) near x = 0.23, corresponding to the composition at which the glass network begins to abruptly stiffen as noted by an upshift in Raman mode frequencies(Xingwei Feng, et al., to be published.). The present observations suggest that the minimum in Cp change at Tg near the stiffness threshold, deduced from ordinary DSC(M. Tatsumisago, B.L. Halfpap, J.L. Green, S.M. Lindsay, and C.A. Angell, Phys. Rev. Lett. 64, 1549 (1990).), i.e., total heat flow, largely derives from the non-reversing component (relaxation related) heat flow near T_g.

Bresser, W. J.; Feng, Xingwei; Boolchand, P.; Schilthuis, J.

1997-03-01

269

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

270

Study of Extended Rigidity Percolation in Se-Te-Sn Glasses Using Dsc  

NASA Astrophysics Data System (ADS)

The effect of addition of Sn on amorphous Se80 Te20 system has been studied using UV VIS NIR Spectrum. The samples are prepared by conventional melt quenching method. It has been found that the addition of Sn reduces the crystalline nature of Se80 Te20 chalcogenide alloy and amorphous samples are obtained for Se80-xTe20Snx(x = 0,2,4,6,8,10,15). The metal influences both the disordered network structure of the glass matrix and the transport properties in accordance with its chemical properties. The glass transition temperature and the crystallization temperatures show detectable changes at composition x = 4, 6 and 10. From the observed DSC results, it is seen that the compositions x = 4 and x = 6 denote the onset and completion of rigidity percolation and x = 10 corresponds to the chemical threshold of the system. The mean bond energy calculated using the covalent bond approach of Tichy and Ticha shows the same anomalies at x = 4, 6 and 10.

Sushama, D.; George, Achamma; Predeep, P.

2008-04-01

271

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

PubMed

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

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

2014-09-01

272

DSC Measurement of Cell Suspensions during Successive Freezing Runs: Implications for the Mechanisms of Intracellular Ice Formation  

Microsoft Academic Search

The formation of intracellular ice in biological cells during freezing is considered almost universally lethal and is the major contributor to cell damage at high cooling rates. Despite its importance, our understanding of the mechanisms of intracellular ice formation (IIF) is still incomplete. In this paper differential scanning calorimetry is used to study IIF in human lyraphocytes in the presence

Gary Bryant

1995-01-01

273

Partitioning of ABA into Bilayers of Di-Saturated Phosphatidylcholines as Measured by DSC  

PubMed Central

Using differential scanning calorimetry, we have investigated partitioning of the plant hormone abscisic acid into a homologous series of di-saturated phosphatidylcholines increasing in chain length from C14 to C19. Partition coefficients calculated from the shift in Tm range from 1280 for DiC14PC to 480 for DiC19PC. The free energy of transfer is chain-length independent with a value of ?G = ?17.4 kJ/mol and an enthalpic contribution of ?H = ?22.6 kJ/mol. The low net entropic contribution of ?T?S = ?5.2 J/mol agrees with the concept of the bilayer effect, but differs from that of the entropy-driven classic hydrophobic effect valid for partitioning between bulk solvents. Preferential location of the hormone in the outer region of the membrane is indicated by characteristic changes in the transition profiles and by comparison with partitioning into organic solvents whose dielectric constants model the interior and exterior regions of the bilayer. Differences in partitioning and surface pKa between the biologically active ct-ABA and the inactive tt-isomer are discussed for biological relevance. PMID:12524285

Katzer, Michael; Stillwell, William

2003-01-01

274

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. PMID:21430957

Sarpietro, Maria Grazia; Castelli, Francesco

2011-01-01

275

Differential scanning calorimetry of chloroquine sulphate exposed to sun, heat and ultraviolet radiation  

Microsoft Academic Search

Chloroquine sulphate, like the phosphate, is an antimalarial formulation widely used in the tropics. The stability of such formulations is therefore of interest in the combat against malaria. A DSC study has been made of the effects of exposure to the sun, heat and UV radiation on the stability of chloroquine sulphate, similarly as performed earlier for chloroquine phosphate. When

I. O. Edafiogho; G. Mulokozi; A. M. Mubokozi; S. Diete-Spiff

1987-01-01

276

Polymer crystallization dynamics, as reflected by differential scanning calorimetry. Part 2: Numerical simulations  

Microsoft Academic Search

With the aid of a model for the kinetics of polymer crystallization, as put forward in previous publications, the shape of DSC-curves and their position on the temperature scale were simulated for various conditions of heat transfer in the apparatus. It turns out that the outcome is very dependent on the assumptions made with respect to these heat transfer conditions.

C. H. Wu; G. Eder; H. Janeschitz-Kriegl

1993-01-01

277

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. PMID:19742173

De Lisi, Rosario; Milioto, Stefania; Muratore, Nicola

2009-01-01

278

Temperature-modulated differential scanning calorimetry as a specific heat spectroscopy  

NASA Astrophysics Data System (ADS)

The ability of modulated differential scanning calorimetry (MDSC) technique to perform a specific heat spectroscopy is examined by comparing MDSC results with those of alternating current calorimetry technique. The comparison is performed on three glass formers: glycerol, propylene glycol and salol. Both techniques give rise to similar activation energies, fragility index m and non-exponential parameters ? for the different compounds. It shows the relevance of the MDSC technique in providing a convenient laboratory probe of the molecular mobility. MDSC data are also compared with available dielectric results. This allows a check on the consistency of the results with regard to the differences between calorimetric and dielectric analysis.

Carpentier, L.; Bustin, O.; Descamps, M.

2002-02-01

279

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

ERIC Educational Resources Information Center

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

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

2006-01-01

280

Historical Roots and Development of Thermal Analysis and Calorimetry  

Microsoft Academic Search

\\u000a Apparently, the first person which used a thought experiment of continuous heating and cooling of an illustrative body was\\u000a curiously the Czech thinker and Bohemian educator [1], latter refugee Johann Amos Comenius (Jan Amos Komenský, 1592–1670) when trying to envisage the properties of substances. In his “Physicae Synopsis”, which he finished in 1629 and published first in Leipzig in 1633,

Jaroslav Šesták; Pavel Hubík; Ji?í J. Mareš

281

Photo – DSC and real time – FT-IR kinetic study of a UV curable epoxy resin containing o-Boehmites  

Microsoft Academic Search

Nanocomposite coatings based on a cycloaliphatic epoxy resin (3,4-epoxycyclohexylmethyl-3?,4?-epoxycyclohexane carboxylate – CE) with two different o-Boehmites (content ranging from 5 to 10wt.%) were prepared by cationic photopolymerization. Two different in situ monitoring techniques, photocalorimetry (p-DSC) and real time FT-IR spectroscopy (RT-IR) were used in order to investigate the kinetics of the photopolymerization process. A theoretical approach for establishing the equivalence

C. Esposito Corcione; M. Frigione; A. Maffezzoli; G. Malucelli

2008-01-01

282

Kinetic studies of a UV-curable powder coating using photo-DSC, real-time FTIR and rheology  

Microsoft Academic Search

The curing kinetics of UV-curable powder coatings based on commercial unsaturated polyesters were monitored using photo-DSC,\\u000a Real-Time FTIR-ATR and a modified rheometer equipped with a UV source. The effect of physical and chemical factors on curing\\u000a such as type of photoinitiator, photoinitiator concentration, temperature and atmosphere of curing were evaluated. Coatings\\u000a containing amounts of photoinitiator from 0.5 to 10 wt% were

P. Castell; M. Wouters; HR Fischer

2007-01-01

283

Microstructural and thermal analysis of Cu-Ni-Sn-Zn alloys by means of SEM and DSC techniques  

Microsoft Academic Search

Purpose: The urgent need to find new, non toxic, high temperature solders caused the abundance of research on multicomponent systems, so as to find new materials that could substitute lead-containing solders. Design\\/methodology\\/approach: In the paper Cu-Ni-Sn-Zn alloys were studied by differential scanning calorymetry (DSC) in argon atmosphere using a heating rate of 10 Kmin-1 and a cooling rate of 15

G. Wnuk; M. Zieliñska

2009-01-01

284

Measurement of glass transition temperature by mechanical (DMTA), thermal (DSC and MDSC), water diffusion and density methods: A comparison study  

Microsoft Academic Search

Glass transition measured by DMTA from the change in slope in storage modulus was 55°C, which was 10.5°C lower than the value measured by tan? peak. Initial glass transition measured by DSC, increased exponentially and reached a constant value of 55°C at or higher heating rate of 30°C\\/min. Transition temperature, measured by MDSC, remained constant up to heating rate 15°C\\/min

Mohammad Shafiur Rahman; Insaaf Mohd Al-Marhubi; Abdullah Al-Mahrouqi

2007-01-01

285

Thermal diffusivity measurements in organic liquids using transient thermal lens calorimetry  

E-print Network

Thermal diffusivity measurements in organic liquids using transient thermal lens calorimetry C. V thermal lens technique. The 532 nm pulses from a frequency doubled Q-switched Nd:YAG laser are used determination of the character- istic time constant of the transient thermal lens signal is verified theoreti

Harilal, S. S.

286

Thermal Denaturation of Whey Proteins in Mixtures with Caseins Studied by Differential Scanning Calorimetry  

Microsoft Academic Search

Thermal unfolding of whey proteins and whey protein-casein mixtures in sim- ulated milk ultrafiltrate was studied by differential scanning calorimetry. The re- sults are reported as transition enthalpy, temperature of peak maximum, and van't Hoff enthalpy related to the sharpness of transition. The results of earlier investiga- tions were reviewed. It is suggested that a large part of reported whey

Marie Paulsson; Petr Dejmek

1990-01-01

287

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

E-print Network

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

Neumark, Daniel M.

288

Determination of caloric values of agricultural crops and crop waste by Adiabatic Bomb Calorimetry  

Technology Transfer Automated Retrieval System (TEKTRAN)

Calorific values of agricultural crops and their waste were measured by adiabatic bomb calorimetry. Sustainable farming techniques require that all potential sources of revenue be utilized. A wide variety of biomass is beginning to be used as alternative fuels all over the world. The energy potentia...

289

Testing multilayer printed wiring board prepreg by differential-scanning calorimetry. Final report  

Microsoft Academic Search

A simplified receiving inspection test for epoxy\\/glass prepreg was developed. This test, which could replace the resin flow test, uses differential scanning calorimetry to measure the glass transition temperature. The glass transition temperature was found to correlate well with the resin flow test.

D. A. Scott; J. W. Lula

1981-01-01

290

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

291

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

E-print Network

The energy density of jellyfish: Estimates from bomb-calorimetry and proximate-composition Thomas K scyphozoan jellyfish (Cyanea capillata, Rhizostoma octopus and Chrysaora hysoscella). First, bomb of these low energy densities for species feeding on jellyfish are discussed. © 2007 Elsevier B.V. All rights

Hays, Graeme

292

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

293

Subsite binding energies of an exo-polygalacturonase using isothermal titration calorimetry  

Technology Transfer Automated Retrieval System (TEKTRAN)

Thermodynamic parameters for binding of a series of galacturonic acid oligomers to an exo-polygalacturonase, RPG16 from Rhizopus oryzae, were determined by isothermal titration calorimetry. Binding of oligomers varying in chain length from two to five galacturonic acid residues is an exothermic proc...

294

Application of polyurethane foam units and calorimetry to microbial monitoring in Lake Donghu  

Microsoft Academic Search

Combined with the national standard biomonitoring method (polyurethane foam units method), calorimetry was applied to study the metabolic activities of PFU microbial communities in fresh water to determine the effects of anthropogenic stresses on the activity of the microbial community. Comparisons were made at four sampling stations with different eutrophic status in Lake Donghu. Water quality variables, species number of

Xiao-Juan Chen; Wei-Song Feng; Yun-Fen Shen; Yi Liu; Wei Miao; Yu-He Yu

2005-01-01

295

Polarised infrared and differential scanning calorimetry studies on oriented vinyl pipe materials  

Microsoft Academic Search

The molecular orientation in a conventionally extruded PVC pipe, a uniaxially oriented PVC pipe and a biaxially oriented PVC pipe has been studied via Infrared dichroism. The degree of order or crystallinity has also been studied by Differential Scanning Calorimetry and also via Infrared Spectroscopy. The fundamental structural difference between the conventional and oriented pipes was that polymer chains were

J. A. Kwon; R. W. Truss

2002-01-01

296

LuAG:Ce fibers for high energy calorimetry  

SciTech Connect

The main objective of this contribution is to point out the potentialities of cerium doped LuAG single crystal as pixels and fibers. We first show that after optimization of growth conditions using Bridgman technology, this composition exhibits very good performances for scintillating applications (up to 26 000 photons/MeV). When grown with the micropulling down technology, fiber shapes can be obtained while the intrinsic performances are preserved. For the future high energy experiments requiring new detector concepts capable of delivering much richer informations about x- or gamma-ray energy deposition, unusual fiber shaped dense materials need to be developed. We demonstrate in this frame that cerium doped LuAG is a serious candidate for the next generation of ionizing radiation calorimeters.

Dujardin, C.; Mancini, C.; Amans, D.; Ledoux, G. [Universite Lyon 1, CNRS, UMR5620, Laboratoire de Physico-Chimie des Materiaux Luminescents, Universite de Lyon, F-69622 Villeurbanne Cedex (France); Abler, D.; Auffray, E.; Lecoq, P. [CERN, 1211 Geneva 23 (Switzerland); Perrodin, D. [Fibercryst, La Doua, Bat. Atrium, Bd Latarjet, F- 69616 Villeurbanne (France); Petrosyan, A.; Ovanesyan, K. L. [Laboratory of Crystal Growth of Luminescent Materials, Institute for Physical Research, Armenian National Academy of Science, 0203 Ashtarak-2 (Armenia)

2010-07-15

297

Water calorimetry-based radiation dosimetry in iridium-192 brachytherapy and proton therapy  

NASA Astrophysics Data System (ADS)

The aim of this work is to develop and evaluate a primary standard for HDR 192Ir brachytherapy sources as well as for active spot scanning proton radiotherapy beams based on stagnant 4 °C water calorimetry. The measurements were performed using an in-house built water calorimeter and a parallel-plate calorimeter vessel. The dose measurement results of the McGill calorimeter were validated in high energy photon beams against Canada's national established primary standard at the NRC. The measurements in brachytherapy were performed with a spring-loaded catheter holder which allowed for the 192Ir source to come directly inside the water calorimeter. The COMSOL MULTIPHYSICS(TM) software was used to solve the heat transport equation numerically for a detailed geometrical model of our experimental setup. In brachytherapy, reference dosimetry protocols were also developed and used to measure the dose to water directly using thimble type ionization chambers and Gafchromic films with traceable 60Co (or higher energy photons) calibration factor. Based on water calorimetry standard, we measured an absolute dose rate to water of 361+/-7 microGy/(h·U) at 55 mm source-to-detector separation. The 1.9 % uncertainty on water calorimetry results is in contrast with the current recommended AAPM TG-43 protocol that achieves at best an uncertainty (k=1) of 2.5 % based on an indirect dose to water measurement technique. All measurement results from water calorimetry, ion chamber, film, and TG-43 agreed to within 0.83 %. We achieved an overall dose uncertainty of 0.4 % and 0.6 % for scattered and scanned proton radiation water calorimetry, respectively. The water calorimetry absorbed dose to water results agreed with those obtained through the currently recommended IAEA TRS-398 protocol (measurements made using an ionization chamber with a 60Co calibration factor) to better than 0.14 % and 0.32 % in scattered and scanned proton beams, respectively. In conclusion, this work forms the foundation for a primary standard in 192Ir brachytherapy and scanning proton radiotherapy using water calorimetry. Not only have we been able to directly and absolute measure the absorbed dose to water, but the uncertainties of dose results over the current accepted protocols have been improved dramatically.

Sarfehnia, Arman

298

Isothermal crystallisation of iPP\\/Vectra blends by DSC and simultaneous SAXS and WAXS measurements employing synchrotron radiation  

Microsoft Academic Search

The isothermal crystallisation behaviour and morphology of blends of isotactic polypropylene, iPP, and a liquid crystal polymer, Vectra A950, has been studied using differential scanning calorimetry, optical microscopy and simultaneous WAXS and SAXS in real-time measurements using synchrotron radiation. It has been observed that Vectra domains act as sites for the nucleation of iPP, and the rate of crystallisation is

F. Javier Torre; M. Milagros Cortázar; M. Ángeles Gómez; Gary Ellis; Carlos Marco

2003-01-01

299

Analysis of Siderite Thermal Decomposition by Differential Scanning Calorimetry  

NASA Technical Reports Server (NTRS)

Characterization of carbonate devolitilization has important implications for atmospheric interactions and climatic effects related to large meteorite impacts in platform sediments. On a smaller scale, meteorites contain carbonates which have witnessed shock metamorphic events and may record pressure/temperature histories of impact(s). ALH84001 meteorite contains zoned Ca-Mg-Fe-carbonates which formed on Mars. Magnetite crystals are found in the rims and cores of these carbonates and some are associated with void spaces leading to the suggestion by Brearley et al. that the crystals were produced by thermal decomposition of the carbonate at high temperature, possibly by incipient shock melting or devolitilization. Golden et al. recently synthesized spherical Mg-Fe-Ca-carbonates from solution under mild hydrothermal conditions that have similar carbonate compositional zoning to those of ALH84001. They have shown experimental evidence that the carbonate-sulfide-magnetite assemblage in ALH84001 can result from a multistep inorganic process involving heating possibly due to shock events. Experimental shock studies on calcium carbonate prove its stability to approx. 60 GPa, well in excess of the approx. 45 GPa peak pressures indicated by other shock features in ALH84001. In addition, Raman spectroscopy of carbonate globules in ALH84001 indicates no presence of CaO and MgO. Such oxide phases should be found associated with the magnetites in voids if these magnetites are high temperature shock products, the voids resulting from devolitilization of CO2 from calcium or magnesium carbonate. However, if the starting material was siderite (FeCO3), thermal breakdown of the ALH84001 carbonate at 470 C would produce iron oxide + CO2. As no documentation of shock effects in siderite exists, we have begun shock experiments to determine whether or not magnetite is produced by the decomposition of siderite within the < 45GPa pressure window and by the resultant thermal pulse to approx. 600 C experienced by ALH84001. Here, we report thermal and compositional characterization of unshocked siderite and its transition to magnetite. Additional information is contained in the original extended abstract.

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

2000-01-01

300

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

301

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

NASA Astrophysics Data System (ADS)

The XIII International Conference on Calorimetry in High Energy Physics was held in Pavia, Italy, 26-30 May 2008, picking up the baton from the 2006 Conference in Chicago. The Conference took place in the unique environment of the Theresian Room of the University Library. The attendees were surrounded by over 40 000 books of general interest and culture, and had the opportunity to see precious volumes written by such people as Galileo, Volta and Faraday. The Workshop brought together more than 120 participants, including senior scientists as well as young physicists, confirming the central and ever-growing role of calorimeters in modern particle physics. The development of these detectors, as stressed by Professor Klaus Pretzl in his lectio magistralis, has made it possible to explore new frontiers in physics, and the present scenario is no exception to this rule. With the LHC experiments almost completely installed and ready to take data, the Conference was an ideal chance to review the status of the different projects, whose development has been followed and discussed throughout the entire Calor series, and to show that they are capable of meeting the design specifications. Other highlights were the performance and physics results of calorimeters installed in currently operating experiments. In the session on astrophysics and neutrinos, the contributions confirmed the key role of calorimeters in this sector and demonstrated their growing application even beyond the field of accelerator physics. Considerable time was devoted to the state-of-the-art techniques in the design and operation of the detectors, while the session on simulation addressed the importance of a thorough understanding of the shower development to meet the demanding requirements of present experiments. Finally, on the R&D side, the particle flow and dual read-out concepts confronted the challenges issued by the next generation of experiments. This complex material was reviewed in 83 presentations, now reported in these proceedings, that were debated in stimulating and fruitful discussions. Outside of the Workshop, the participants were able to visit the historical Halls and Museum of the University, whose foundation dates back to the year 1361, and to enjoy a visit to the Certosa, a Carthusian monastery renowned for its exuberant architecture. Pavia welcomed the Conference participants by opening the doors of the Town Hall and offering a reception during which the Mayor's address underlined the importance of research and its applications in modern society. The successful organization and the smooth running of the Conference is due to many people and Institutions. We gratefully acknowledge the financial support of the Istituto Nazionale di Fisica Nucleare (INFN), the Department of Nuclear and Theoretical Physics and the University of Pavia, that made the Workshop possible, together with the contribution of our sponsors. The University also opened some rooms of the Chancellor's suite for the lunch and coffee breaks, and hosted the Conference Secretariat. We would like to express our deepest gratitude to the INFN and Department technical staff, who helped to prepare the Hall for the Conference and to provide computer services, and to the staff of the Theresian Library, who gave us access to the Room and organized a display of the many historical books from their vast and precious collections which are of interest to physicists. Above all, the success of the meeting is due to the participants who animated it, and in particular to the speakers for their dedicated work in preparing their excellent talks and in providing the write-ups, and to the conveners for their essential role in shaping an interesting and well balanced scientific program. Finally, we wish to thank the International Advisory Committee for their unfailing support and for offering us the opportunity to organize this Conference in Pavia. Michele Livan Chairman, Organizing Committee International Advisory Commitee M Danilov, ITEP Moscow M Diemoz, INFN Roma I A Ereditato, Bern F Fabbri, I

Livan, Michele

2009-07-01

302

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

303

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. PMID:24155671

Jiang, Xuan-Zhao; Wei, Dan-Dan; Yang, Wen-Jia; Dou, Wei; Chen, Shi-Chun; Wang, Jin-Jun

2013-01-01

304

Comparison of calorimetry and destructive analytical measurement techniques for excess plutonium powders  

SciTech Connect

In Dec. 1994, IAEA safeguards were initiated on inventory of Pu- bearing materials, originating from the US nuclear weapons complex, at vault 3 of DOE`s Plutonium Finishing Plant at Hanford. Because of the diversity and heterogeneity of the Pu, plant operators have increasingly used calorimetry for accountability measurements. During the recent commencement of IAEA safeguards at vault 3, destructive (electrochemical titration) methods were used to determine Pu concentrations in subsamples of inventory items with widely ranging chemical purities. The Pu concentrations in the subsamples were determined and contribution of heterogeneity to total variability was identified. Measurement results, gathered by PFP and IAEA laboratories, showed total measurement variability for calorimetry to be comparable with or lower than those of sampling and chemical analyses.

Welsh, T.L.

1996-03-15

305

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

NASA Astrophysics Data System (ADS)

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

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

2003-01-01

306

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

SciTech Connect

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

Russ, J.S.

1988-01-01

307

Method for direct deconvolution of heat signals in transient adsorption calorimetry  

NASA Astrophysics Data System (ADS)

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

Wolcott, Christopher A.; Campbell, Charles T.

2015-03-01

308

The investigation of photoinitiated polymerization of multifunctional acrylates with TX-BT by Photo-DSC and RT-FTIR  

Microsoft Academic Search

Photopolymerization of multifunctional acrylates with 3H-5-Thia-1,2,3-triaza-cyclopenta[b]anthracene-10-one (TX-BT) as the one-component photoinitiator was investigated using real-time Fourier transform infrared spectroscopy (RT-FTIR). Photo-differential scanning calorimetric (Photo-DSC) technique was used to study the gelation of trimethylolpropanetriacrylate (TMPTA), P-3038 (epoxydiacrylate (EA) 75% and tripropyleneglycoldiacrylate (TPGDA) 25%) and tripropyleneglycol diacrylate (TPGDA)+P-3038 in the presence of TX-BT. Photopolymerization reactions were performed under different conditions of initiator

Duygu Sevinc Esen; Feyza Karasu; Nergis Arsu

2011-01-01

309

Diclofenac Salts. V. Examples of Polymorphism among Diclofenac Salts with Alkyl-hydroxy Amines Studied by DSC and HSM  

PubMed Central

Nine diclofenac salts prepared with alkyl-hydroxy amines were analyzed for their properties to form polymorphs by DSC and HSM techniques. Thermograms of the forms prepared from water or acetone are different in most cases, suggesting frequent examples of polymorphism among these salts. Polymorph transition can be better highlighted when analysis is carried out by thermo-microscopy, which in most cases made it possible to observe the processes of melting of the metastable form and re-crystallization of the stable one. Solubility values were qualitatively related to the crystal structure of the salts and the molecular structure of the cation.

Fini, Adamo; Cavallari, Cristina; Ospitali, Francesca

2010-01-01

310

Measurement of glass transition temperature by mechanical (DMTA), thermal (DSC and MDSC), water diffusion and density methods: A comparison study  

NASA Astrophysics Data System (ADS)

Glass transition measured by DMTA from the change in slope in storage modulus was 55 °C, which was 10.5 °C lower than the value measured by tan ? peak. Initial glass transition measured by DSC, increased exponentially and reached a constant value of 55 °C at or higher heating rate of 30 °C/min. Transition temperature, measured by MDSC, remained constant up to heating rate 15 °C/min and then decreased. The glass transition values determined from reversible heat flow was 60 °C. The break in diffusivity and density (i.e. volume) was observed at 50 °C below the glass transition temperature measured by thermal and mechanical methods.

Rahman, Mohammad Shafiur; Al-Marhubi, Insaaf Mohd; Al-Mahrouqi, Abdullah

2007-06-01

311

The heat capacity of fluorinated propane and butane derivatives by differential scanning calorimetry  

Microsoft Academic Search

The constant pressure liquid-phase heat capacities of 21 hydrogen containing fluorinated propane and butane derivatives and one fluorinated ether (CF3OCF2H) with boiling points ranging from -34.6° to 76.7°C have been measured to 3% accuracy by differential scanning calorimetry at 40°C. The measurements are needed to help identify alternative refrigerants and blowing agents that do not deplete the stratospheric ozone layer.

Sun-Hee Hwang; D. D. DesMarteau; A. L. Beyerlein; N. D. Smith; P. Joyner

1992-01-01

312

31P NMR and isothermal titration calorimetry studies on polyoxomolybdates-catalyzed hydrolysis of ATP  

Microsoft Academic Search

ATP hydrolysis in the presence of polyoxomolybdates at pH levels of 6, 4, and 2 has been investigated with a help of high pressure liquid chromatography (HPLC) analyses, 31P- and 1H NMR measurements, and isothermal titration calorimetry (ITC). The polyoxomolybdates-induced ATP-hydrolysis proceeded satisfactorily in pH<6 media at 20°C with an optimum pH level of 4, while it was significantly depressed

Eri Ishikawa; Toshihiro Yamase

2006-01-01

313

How should body heat storage be determined in humans: by thermometry or calorimetry?  

Microsoft Academic Search

Summary  The aim of this study was to determine whether in humans there are differences in the heat storage calculated by partitional calorimetry (S, the balance of heat gains and heat losses) compared to the heat storage obtained by conventional methods (thermometry) via either core temperature or mean body temperatures (\\u000a$$\\\\bar T_b = 0.8T_c + 0.2\\\\bar T_{sk} $$\\u000a, whereT

André L. Vallerand; Gustave Savourey; Anne-Marie Hanniquet; Jacques H. M. Bittel

1992-01-01

314

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

SciTech Connect

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

Li Bincheng; Blaschke, Holger; Ristau, Detlev

2006-08-10

315

Estimating relative physical workload using heart rate monitoring: a validation by whole-body indirect calorimetry  

Microsoft Academic Search

Measuring physical workload in occupational medicine is fundamental for risk prevention. An indirect measurement of total and relative energy expenditure (EE) from heart rate (HR) is widely used but it has never been validated. The aim of this study was to validate this HR-estimated energy expenditure (HREEE) method against whole-body indirect calorimetry. Twenty-four-hour HR and EE values were recorded continuously

Martin Garet; Gil Boudet; Christophe Montaurier; Michel Vermorel; Jean Coudert; Alain Chamoux

2005-01-01

316

Modulated differential scanning calorimetry: 8. Interface development between films of polyepichlorohydrin and poly(vinyl acetate)  

Microsoft Academic Search

A thermal method with the potential to determine the weight fraction and the interfacial thickness in multiphase polymer materials is described. The extent of interdiffusion, and hence the development of an interface between two miscible polymers, polyepichlorohydrin and poly(vinyl acetate), with time at 100°C has been studied by means of modulated-temperature differential scanning calorimetry. This polymer pair is known to

M. Reading

1997-01-01

317

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

Microsoft Academic Search

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

G. Perseghin

2001-01-01

318

Indirect calorimetry: variability of consecutive baseline determinations of carbohydrate and fat utilization from gas exchange measurements.  

PubMed

During the past years, substantial methodological and interpretational limitations of indirect calorimetry, particularly concerning fuel utilisation, have been discussed. The aim of the present study was to evaluate short-time intraindividual variability of two consecutive gas exchange measurement series and of calculated data on total energy expenditure/24 h and carbohydrate and fat utilisation. 24 healthy volunteers (16 f, 8 m, 34.7 +/- 13.1 yrs) were admitted to the study. Trials were performed supine after an 12 h overnight fast. After a resting period of 30-45 min and following equilibration of respiratory values for at least 10 min prior to the test, indirect calorimetry measurements were performed using the Sensor-Medics 2.900 device (canopy). Two measurements series lasting up to 30 min each were performed 15-20 min apart. Total energy production/24 h as well as that obtained from carbohydrate and fat utilisation were calculated in both measurement series. Protein utilisation was derived from estimated urinary 24 h nitrogen excretion. O2-consumption, CO2-production, the respiratory quotient and total energy production/24 h show acceptable mean coefficients of variation of 3.7%, 4.6%, 3.5% and 3.6%, respectively. In contrast, carbohydrate and fat utilisation values demonstrate a coefficient of variation of 21.2% and 17.4%, respectively, suggesting considerable impression of estimates of fuel utilisation by indirect calorimetry. We conclude that for research purposes, particularly over short-time periods, indirect calorimetry provides sufficient accuracy only in estimating total resting energy production, while considerable uncertainty exists in using this method to assess carbohydrate and fat utilisation. PMID:9049647

Gasic, S; Schneider, B; Waldhäusl, W

1997-01-01

319

Thermal analysis of failed-batch palm oil by differential scanning calorimetry  

Microsoft Academic Search

Thermal behavior of palm oil samples drawn from the batch crystallizers that failed during crystallization and of a control\\u000a oil that was drawn from a batch that produced good crystallization were analyzed by differential scanning calorimetry under\\u000a constant heating and cooling conditions. Four polymorphs—?’2, ?, ?’1, and ?1—were observed, and their temperatures were tabulated. A rapid and sudden surge of

Y. B. Che Man; P. Z. Swe

1995-01-01

320

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

PubMed Central

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

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

1991-01-01

321

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

Microsoft Academic Search

Is single-strand DNA translatable? Since the 60s, the question still remains whether or not DNA could be directly translated into protein. Some discrepancies in the results were reported about functional translation of single-strand DNA but all results converged on a similar behavior of RNA and ssDNA in the initiation step. Isothermal Titration Calorimetry method was used to determine thermodynamic constants

Luminita Damian; Claire Marty-Detraves; Mathias Winterhalter; Didier Fournier; Laurent Paquereau

2009-01-01

322

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

323

Energy requirements and the use of predictive equations versus indirect calorimetry in critically ill patients.  

PubMed

Nutrition support has been shown to have a positive impact on critically ill patients who meet their defined goals of nutrition therapy. However, inappropriate energy assessment can contribute to under- or overfeeding resulting in deleterious effects. Thus, assessment of energy expenditure in critically ill patients is crucial to prevent negative impacts from inappropriate feeding. Currently, the optimal energy requirement and appropriate energy assessment in these patients is controversial. Indirect calorimetry or predictive equations have been suggested to evaluate energy expenditure in critically ill patients. Indirect calorimetry is a gold standard for evaluating energy expenditure, but it is not always available and has some limitations. Many predictive equations, therefore, have been developed to predict energy expenditure in critically ill patients. However, these equations cannot be used generally in these patients since they were developed in a unique patient population. Many studies compared measured energy expenditure with predictive energy expenditure, but the data regarding accuracy is not robust. Therefore, clinicians should consider using these equations carefully based on the current supporting data. Indirect calorimetry is recommended for use in evaluating energy expenditure in critically ill patients if it is available. PMID:25610953

Wichansawakun, Sanit; Meddings, Liisa; Alberda, Cathy; Robbins, Sarah; Gramlich, Leah

2015-02-01

324

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

PubMed

A mathematical model based on conservation of energy has been developed and used to simulate the temperature responses of cones of the Australian cycads Macrozamia lucida and Macrozamia. macleayi during their daily thermogenic cycle. These cones generate diel midday thermogenic temperature increases as large as 12 °C above ambient during their approximately two week pollination period. The cone temperature response model is shown to accurately predict the cones' temperatures over multiple days as based on simulations of experimental results from 28 thermogenic events from 3 different cones, each simulated for either 9 or 10 sequential days. The verified model is then used as the foundation of a new, parameter estimation based technique (termed inverse calorimetry) that estimates the cones' daily metabolic heating rates from temperature measurements alone. The inverse calorimetry technique's predictions of the major features of the cones' thermogenic metabolism compare favorably with the estimates from conventional respirometry (indirect calorimetry). Because the new technique uses only temperature measurements, and does not require measurements of oxygen consumption, it provides a simple, inexpensive and portable complement to conventional respirometry for estimating metabolic heating rates. It thus provides an additional tool to facilitate field and laboratory investigations of the bio-physics of thermogenic plants. PMID:22995822

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

2012-12-21

325

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

326

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

PubMed Central

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

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

2013-01-01

327

An Efficient Computational Approach to Characterize DSC-MRI Signals Arising from Three-Dimensional Heterogeneous Tissue Structures  

PubMed Central

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

328

Characterization of compression-molded UHMWPE, PMMA and PMMA/MMA treated UHMWPE: density measurement, FTIR-ATR, and DSC.  

PubMed

Considered one of the weak links in the total hip replacement (THR), efforts to enhance the interfacial strength between bone cement and ultra-high molecular weight polyethylene (UHMWPE) acetabular cup had been conducted in this laboratory. Following the successful demonstration of high interfacial strengths for our new acetabular component design, the nature of physical, chemical, and thermal property of the compression-molded specimens, including UHMWPE, PMMA/MMA treated UHMWPE, and PMMA has been investigated in this study. Density results from a density gradient column showed that the molding processes and conditions were adequate for complete sintering of UHMWPE and PMMA powders. FTIR-ATR results gave a direct evidence that PMMA did exist in the PMMA/MMA treated UHMWPE matrix. It also revealed a clear diffusion-related behavior across the interface. Under the high temperature and pressure, the UHMWPE powders undergo drastic changes of their morphology and crystalline structures. These changes were examined by differential scanning calorimeter (DSC) which showed a large difference in terms of % crystallinity. The percent of PMMA deposited in the treated UHMWPE was 17.8%, 18.8%, and 24.3% from the analyses of density, FTIR-ATR, and DSC, respectively. Finally, an evidence of diffusive behavior at the interface exhibited diffusion of PMMA occurring across the interfaces between the treated UHMWPE and UHMWPE or PMMA. PMID:11790863

Park, K D; Khang, G S; Lee, H B; Park, J B

2001-01-01

329

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

330

Studies on the formability of Al-based metallic glasses\\/nanocomposites based on isochronal DSC analysis  

Microsoft Academic Search

The Al86Si0.5Ni4.06Co2.94Y6Sc0.5 metallic glass of highly improved glass-forming ability (GFA) has been investigated by isochronal differential scanning calorimetry measurements, as well as the Al85Ni5Co2Y8 for comparison. The experimental results indicate that the Al86Si0.5Ni4.06Co2.94Y6Sc0.5 exhibits enlarged temperature interval between the first and second crystallization onsets (termed as primary fcc-Al\\/glass region), as well as enlarged second activation energy (Ep2) against the nucleation

Longchao Zhuo; Tao Zhang

2010-01-01

331

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

E-print Network

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

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

2012-11-29

332

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

E-print Network

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

Jervis, Freddy Xavier

2012-01-01

333

Apparent Cooperative Assembly of the Bacterial Cell Division Protein FtsZ Demonstrated by Isothermal Titration Calorimetry*  

E-print Network

by Isothermal Titration Calorimetry* Received for publication, January 27, 2003 Published, JBC Papers in Press isothermal titration calorim- etry (ITC) to measure the heat of FtsZ self-association under various

Erickson, Harold P.

334

HEAT OF HYDRATION OF SALTSTONE MIXES-MEASUREMENT BY ISOTHERMAL CALORIMETRY  

SciTech Connect

This report provides initial results on the measurement of heat of hydration of Saltstone mixes using isothermal calorimetry. The results were obtained using a recently purchased TAM Air Model 3116 Isothermal Conduction Calorimeter. Heat of hydration is an important property of Saltstone mixes. Greater amounts of heat will increase the temperature of the curing mix in the vaults and limit the processing rate. The heat of hydration also reflects the extent of the hydraulic reactions that turn the fluid mixture into a ''stone like'' solid and consequently impacts performance properties such as permeability. Determining which factors control these reactions, as monitored by the heat of hydration, is an important goal of the variability study. Experiments with mixes of portland cement in water demonstrated that the heats measured by this technique over a seven day period match very well with the literature values of (1) seven day heats of hydration using the standard test method for heat of hydration of hydraulic cement, ASTM C 186-05 and (2) heats of hydration measured using isothermal calorimetry. The heats of hydration of portland cement or blast furnace slag in a Modular Caustic Side Solvent Extraction Unit (MCU) simulant revealed that if the cure temperature is maintained at 25 C, the amount of heat released over a seven day period is roughly 62% less than the heat released by portland cement in water. Furthermore, both the blast furnace slag and the portland cement were found to be equivalent in heat production over the seven day period in MCU. This equivalency is due to the activation of the slag by the greater than 1 Molar free hydroxide ion concentration in the simulant. Results using premix (a blend of 10% cement, 45% blast furnace slag, and 45% fly ash) in MCU, Deliquification, Dissolution and Adjustment (DDA) and Salt Waste Processing Facility (SWPF) simulants reveal that the fly ash had not significantly reacted (undergone hydration reactions) after seven days (most likely less than 5%). There were clear differences in the amount of heat released and the peak times of heat release for the three different simulants. It turns out that SWPF simulant mixes give off greater heat than does MCU and DDA simulant mixes. The temperature dependence of the heat of hydration was measured by carrying out these measurements at 25, 40 and 55 C. In general, the peak times shifted to shorter times as the isothermal temperature increased and the amount of heat released was independent of temperature for DDA and MCU but slightly higher at higher temperatures for SWPF. The goal of this study is to apply this technique to the measurement of the heat of hydration of mixes that will be made as part of the variability study. It is important to understand which variables will impact (and to what extent) the amount of heat generated and the peak times for the heat release. Those variables that can be controlled can then be tuned to adjust the heat of hydration as long as the other properties are still acceptable. The first application of heat of hydration measurements to the variability study was completed and the results presented in this report. These measurements were made using Phase VI mixes (SWPF simulants) following a statistical design that included variation in the compositional and operational variables. Variation in both the amount of heat released and the peak times for the heat release were observed. The measured ranges were 23 Joules per gram of premix for the heat release and 23 hours for the peak time of heat release at 25 C. Linear models with high R{sup 2} values and no statistical evidence for lack of fit were developed that relate the amount of heat release and the peak time for heat release for the Phase VI mixes to certain variables. The amount of heat released was a function of the aluminate and portland cement concentrations as well as the temperature of mixing. The peak time for heat release was a function of aluminate, portland cement and total nitrate plus nitrite concentrations. A comparison was made of the mea

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

2007-07-02

335

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

PubMed

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

Ababou, Abdessamad; Ladbury, John E

2006-01-01

336

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

337

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

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

338

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

339

Psychometric evaluation of the Korean version of the Diabetes Symptom Checklist-Revised (DSC-R) for Patients with Type 2 Diabetes  

PubMed Central

Background This study was to elucidate the psychometric properties of the Korean version of the Diabetes Symptom Checklist-Revised (K-DSC-R), which is a patient-reported outcome measure of diabetes symptom burden. Methods A sample of 432 Korean patients with diabetes was recruited from university hospitals. The data were analyzed using exploratory factor analysis (EFA), confirmatory factor analysis (CFA), multitrait/multi-item correlation, Pearson’s correlation, t-test, ANOVA, and Cronbach’s alpha for construct, item-convergent/discriminant, concurrent, and known-groups validity, and internal consistency reliability. Results EFA extracted a total of 29 items clustered into 7 subscales from the K-DSC-R. The construct of the seven-subscales was supported by CFA. The scaling success rates of item-convergent validity were 100% for all subscales, and those of item-discriminant validity ranged from 83.3% to 100%. Patients in more-depressed groups and in the HbA1c-uncontrolled group had higher K-DSC-R scores, satisfying the known-groups validity. The subscales of the K-DSC-R were moderately correlated with health-related quality of life, indicative of the established concurrent validity. The Cronbach’s alpha of the K-DSC-R was 0.92. Conclusions The psychometric properties of the K-DSC-R have been established. It is thus appropriate for use with respect to reliability and validity in practice and clinical trials for Korean patients with type 2 diabetes. PMID:24885358

2014-01-01

340

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

341

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

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

342

Reference dosimetry for light-ion beams based on graphite calorimetry.  

PubMed

Developments in hadron therapy require efforts to improve the accuracy of the dose delivered to a target volume. Here, the determination of the absorbed dose under reference conditions was analysed. Based on the International Atomic Energy Agency TRS-398 code of practice, for hadron beams, the combined standard uncertainty on absorbed dose to water under reference conditions, derived from ionisation chambers, is too large. This uncertainty is dominated by the beam quality correction factors, [Formula: see text], mainly due to the mean energy to produce one ion pair in air, wair. A method to reduce this uncertainty is to carry out primary dosimetry, using calorimetry. A [Formula: see text]-value can be derived from a direct comparison between calorimetry and ionometry. Here, this comparison is performed using a graphite calorimeter in an 80-MeV A(-1) carbon ion beam. Assuming recommended TRS-398 values of water-to-graphite stopping power ratio and the perturbation factor for an ionisation chamber, preliminary results indicate a wair-value of 35.5 ± 0.9 J C(-1). PMID:24336190

Rossomme, S; Palmans, H; Thomas, R; Lee, N; Duane, S; Bailey, M; Shipley, D; Bertrand, D; Romano, F; Cirrone, P; Cuttone, G; Vynckier, S

2014-10-01

343

Integration of ultrafast scanning calorimetry with micro-Raman spectroscopy for investigation of metastable materials.  

PubMed

A stage-type ultrafast scanning calorimetry (ST-UFSC) with controlled heating and cooling rates up to 10(5) K?s(-1) was designed to integrate with microstructural characterization. This enables us to precisely control the evolution of fast transitional states of metastable samples provided by the UFSC platform, and to follow subtle structural changes between intermediate stages. As an example, we collected the Raman spectra of poly(ethylene terephthalate) quenched at different crystallization states obtained by programed rapid cooling and heating processes. Because of the very small sample mass for UFSC measurements, from minimum few nanograms to sub-micrograms, the sample's temperature is very sensitive to the perturbation from the laser illumination of the Raman spectrometer. Real time temperature monitoring and compensation was accompanied during the whole process of in situ spectroscopy. The results showed a good agreement of crystallization kinetics obtained from the Raman spectroscopy and from the calorimetric melting enthalpy, given that the sample temperature is well controlled during spectroscopic measurements and that the heating rate for calorimetry is fast enough to suppress structural reorganization during heating scans. We expect that the ST-UFSC is suitable to be integrated with other micro-analysis techniques to investigate the structure and dynamics of metastable states obtained by fast thermal treatments. PMID:25085160

Wei, Lai; Jiang, Jing; Shan, Meijuan; Chen, Wei; Deng, Yu; Xue, Gi; Zhou, Dongshan

2014-07-01

344

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

SciTech Connect

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

Anderson, D.F.

1989-06-26

345

Direct calorimetry of free-moving eels with manipulated thyroid status  

NASA Astrophysics Data System (ADS)

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

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

2007-02-01

346

DSC studies of gamma irradiation influence on gelatinisation and amylose-lipid complex transition occurring in wheat starch  

NASA Astrophysics Data System (ADS)

Differential scanning calorimetry studies are presented dealing with the influence of gamma irradiation (carried out in the solid state) on the structure of amylose-lipid complex in wheat starch . Suspensions of the control and the wheat starch irradiated with a 30 kGy gamma rays (characterised by starch-to-water ratio of 1:1 and ca. 1:4) were examined during several courses of heating and cooling at rates of 2.5 and 10°C min -1. Differences were observed between enthalpy and temperature of gelatinisation and amylose-lipid complex transition as well as retrogradation taking place in the suspensions and gels of the control and the irradiated starch. The influence of the preceding heating and cooling on further transformations of the amylose-lipid complex differs for the control and the irradiated samples.

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

2003-12-01

347

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

PubMed

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

Meneses, Erick; Mittermaier, Anthony

2014-10-01

348

Thermal characterization of polyethylene glycols applied in the pharmaceutical technology using differential scanning calorimetry and hot stage microscopy  

Microsoft Academic Search

In the present study, the effect of the molecular weight and thermal treatments on commercial polyethylene glycols (PEG) samples used in the pharmaceutical processing technology, has been analyzed using DSC and HSM. The molecular weight of these polymers range from 1500 to 200000. Thermal investigations on the melting behavior of original PEG samples (as received from the manufacturer) showed only

J. M. Ginés; M. J. Arias; A. M. Rabasco; C. Novák; A. Ruiz-Conde; P. J. Sánchez-Soto

1996-01-01

349

Phase transitions and molecular motions in [Cd(H{sub 2}O){sub 6}](BF{sub 4}){sub 2} studied by DSC, {sup 1}H and {sup 19}F NMR and FT-MIR  

SciTech Connect

Two solid phase transitions of [Cd(H{sub 2}O){sub 6}](BF{sub 4}){sub 2} occurring on heating at T{sub C2}=183.3K and T{sub C1}=325.3K, with 2K and 5K hysteresis, respectively, were detected by differential scanning calorimetry (DSC). High value of entropy changes indicated large orientational disorder of the high temperature and intermediate phase. Nuclear magnetic resonance ({sup 1}H NMR and {sup 19}F NMR) relaxation measurements revealed that the phase transitions at T{sub C1} and T{sub C2} were associated with a drastic and small change, respectively, of the both spin-lattice relaxation times: T{sub 1}({sup 1}H) and T{sub 1}({sup 19}F). These relaxation processes were connected with the 'tumbling' motions of the [Cd(H{sub 2}O){sub 6}]{sup 2+}, reorientational motions of the H{sub 2}O ligands, and with the iso- and anisotropic reorientation of the BF{sub 4}{sup -} anions. The cross-relaxation effect was observed in phase III. The line width and the second moment of the {sup 1}H and {sup 19}F NMR line measurements revealed that the H{sub 2}O reorientate in all three phases of the title compound. On heating the onset of the reorientation of 3 H{sub 2}O in the [Cd(H{sub 2}O){sub 6}]{sup +2}, around the three-fold symmetry axis of these octahedron, causes the isotropic reorientation of the whole cation. The BF{sub 4}{sup -} reorientate isotropically in the phases I and II, but in the phase III they perform slow reorientation only about three- or two-fold axes. A small distortion in the structure of BF{sub 4}{sup -} as well as of [Cd(H{sub 2}O){sub 6}]{sup 2+} is postulated. The temperature dependence of the bandwidth of the O-H stretching mode measured by Fourier transform middle infrared spectroscopy (FT-MIR) indicated that the activation energy for the reorientation of the H{sub 2}O did not change much at the T{sub C2} phase transition.

Mikuli, E. [Department of Chemical Physics, Faculty of Chemistry, Jagiellonian University, Ulica Ingardena 3, 30-060 Cracow (Poland)]. E-mail: mikuli@chemia.uj.edu.pl; Grad, B. [Department of Chemical Physics, Faculty of Chemistry, Jagiellonian University, Ulica Ingardena 3, 30-060 Cracow (Poland); Medycki, W. [Institute of Molecular Physics, Polish Academy of Sciences, ul. Smoluchowskiego 17, 60-179 Poznan (Poland); Holderna-Natkaniec, K. [Institute of Physics, A. Mickiewicz University, Umultowska 85, 61-606 Poznan (Poland)

2004-10-01

350

Fast Scanning Calorimetry study of non-equilibrium relaxation in 2-Ethyl-1-Hexanol  

NASA Astrophysics Data System (ADS)

Fast scanning calorimetry (FSC), capable of heating rates in excess of 1000000 K/s, was combined with vapor deposition technique to investigate non-equilibrium relaxation in micrometer thick ultraviscous of 2-Ethyl-1-Hexanol (2E1H) films under high vacuum conditions. Rapid heating of 2E1H samples prepared at temperatures above approximately 145 K (standard glass transition temperature of 2E1H, Tgs), resulted in well manifested dynamic glass transitions at temperatures tens of degrees higher than Tgs. Furthermore, strong and complex dependence of dynamic glass transition temperature on the sample's initial state, i.e., the starting temperature of FSC scan was also observed. We discuss implications of these results for contemporary models of non-equilibrium relaxation in glasses and supercooled liquids.

Sadtchenko, Vlad; Bhattacharya, Deepanjan; Pane, Candace

2012-02-01

351

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

352

Toward New High Temperature Reference Materials for Calorimetry and Thermal Analysis  

NASA Astrophysics Data System (ADS)

The French National Metrology Laboratory LNE-LCM has developed a high temperature reference facility for accurate measurements of the specific heat capacity and of the enthalpy of fusion of materials over the temperature range [23 °C, 1000 °C]. The metrological approach was to modify a commercial Calvet calorimeter in order to lower the uncertainty of measurement and to insure the metrological traceability of the measurements to the SI units, in particular by designing a new calibration system. The enthalpies of fusion of pure metals (indium, tin and silver) and of a binary alloy Ag-28Cu have been measured. The results obtained on the three pure metallic materials are in very good agreement with data obtained by other National Metrology Institutes (NMIs) using adiabatic calorimetry.

Razouk, R.; Hay, B.; Himbert, M.

2014-08-01

353

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

PubMed

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

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

2012-01-01

354

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

NASA Astrophysics Data System (ADS)

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

Medvedeva, Tatiana

355

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

356

The Yang-Yang anomaly in liquid-liquid criticality: Experimental evidence from adiabatic scanning calorimetry  

NASA Astrophysics Data System (ADS)

Using adiabatic scanning calorimetry, we have found the first experimental evidence of the Yang-Yang anomaly in liquid-liquid criticality from high-resolution two-phase isobaric heat capacity measurements for the binary mixture 3-pentanol + nitromethane. The results suggest a rather strong effect. The critical amplitude of the partial molar heat capacity is higher for the component with larger molecular volume, in accordance with the predictions of complete scaling as obtained from the customary observed asymmetric behavior of the coexistence-curve diameter. This consolidates complete scaling as the true formulation of fluid-fluid criticality. The quantitative analysis indicates that molecular size is not the only microscopic factor at play in asymmetric liquid-liquid criticality.

Losada-Pérez, Patricia; Tripathi, Chandra Shekhar Pati; Leys, Jan; Cerdeiriña, Claudio A.; Glorieux, Christ; Thoen, Jan

2012-01-01

357

Dual-Readout Calorimetry for High-Quality Energy Measurements. Final Report  

SciTech Connect

This document constitutes the final report on the project Dual-Readout Calorimetry for High-Quality Energy Measurements. The project was carried out by a consortium of US and Italian physicists, led by Dr. Richard Wigmans (Texas tech University). This consortium built several particle detectors and tested these at the European Center for Nuclear Research (CERN) in Geneva, Switzerland. The idea arose to use scintillating crystals as dual-readout calorimeters. Such crystals were of course already known to provide excellent energy resolution for the detection of particles developing electromagnetic (em) showers. The efforts to separate the signals from scintillating crystals into scintillation and Cerenkov components led to four different methods by which this could be accomplished. These methods are based on a) the directionality, b) spectral differences, c) the time structure, and d) the polarization of the signals.

Wigmans, Richard; Nural, Akchurin

2013-09-01

358

Modulated calorimetry of poly(1,4-oxybenzoate), poly(2,6-oxynaphthoate), and their copolymers  

SciTech Connect

Poly(1,4-oxybenzoate) (POB) and poly(2,6-oxynaphthoate) (PON) and their copolymers which have a well-established phase diagram have been studied with temperature-modulated differential scanning calorimetry (TMDSC). All the analyzed polymers have more than one disordering transition between the glass transition (from 400 to 430 K) and decomposition (starting at 700 K). Above the glass transition, the reversible heat capacity, Cp, increases beyond that calculated from the crystallinity and the known Cp of the solid and melt. This is likely due to an increase of mobility within the crystals and/or a possible rigid-amorphous fraction (mainly for the copolymers). The disordering transitions are largely irreversible, supporting the observation that semicrystalline, linear macromolecules show decreasing amounts of locally reversible melting with increasing rigidity and crystal perfection.

Ma, J [University of Tennessee, Knoxville (UTK); Habenschuss, A [Oak Ridge National Laboratory (ORNL); Wunderlich, B [University of Tennessee, Knoxville (UTK) & Oak Ridge National Laboratory (ORNL)

2008-01-01

359

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

PubMed

G-quadruplexes are higher-order nucleic acids structures formed by G-rich sequences that are stabilized by tetrads of hydrogen-bonded guanine bases. Recently, there has been growing interest in the study of G-quadruplexes because of their possible involvement in many biological processes. Isothermal titration calorimetry (ITC) has been proven to be a useful tool to study the energetic aspects of G-quadruplex interactions. Particularly, ITC has been applied many times to determine the thermodynamic properties of drug-quadruplex interactions to screening among various drugs and to address drug design. In the present review, we will focus on the ITC studies of G-quadruplex structures and their interaction with proteins and drugs and the most significant results will be discussed. PMID:19742177

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

2009-06-01

360

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

E-print Network

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

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

2010-01-06

361

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

PubMed

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

Ababou, Adessamad; Ladbury, John E

2007-01-01

362

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

SciTech Connect

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

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

2013-11-13

363

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

E-print Network

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

Jeembaeva, Meerim; Castelnovo, Martin; Evilevitch, Alex

2010-01-01

364

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

PubMed Central

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

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

2014-01-01

365

Indirect calorimetry in laboratory mice and rats: principles, practical considerations, interpretation and perspectives.  

PubMed

In this article, we review some fundamentals of indirect calorimetry in mice and rats, and open the discussion on several debated aspects of the configuration and tuning of indirect calorimeters. On the particularly contested issue of adjustment of energy expenditure values for body size and body composition, we discuss several of the most used methods and their results when tested on a previously published set of data. We conclude that neither body weight (BW), exponents of BW, nor lean body mass (LBM) are sufficient. The best method involves fitting both LBM and fat mass (FM) as independent variables; for low sample sizes, the model LBM + 0.2 FM can be very effective. We also question the common calorimetry design that consists of measuring respiratory exchanges under free-feeding conditions in several cages simultaneously. This imposes large intervals between measures, and generally limits data analysis to mean 24 h or day-night values of energy expenditure. These are then generally compared with energy intake. However, we consider that, among other limitations, the measurements of Vo(2), Vco(2), and food intake are not precise enough to allow calculation of energy balance in the small 2-5% range that can induce significant long-term alterations of energy balance. In contrast, we suggest that it is necessary to work under conditions in which temperature is set at thermoneutrality, food intake totally controlled, activity precisely measured, and data acquisition performed at very high frequency to give access to the part of the respiratory exchanges that are due to activity. In these conditions, it is possible to quantify basal energy expenditure, energy expenditure associated with muscular work, and response to feeding or to any other metabolic challenge. This reveals defects in the control of energy metabolism that cannot be observed from measurements of total energy expenditure in free feeding individuals. PMID:22718809

Even, Patrick C; Nadkarni, Nachiket A

2012-09-01

366

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

NASA Astrophysics Data System (ADS)

The XVth International Conference on Calorimetry in High Energy Physics, CALOR2012, was held in Santa Fe, New Mexico from 4-8 June 2012. The series of conferences on calorimetry started in 1990 at Fermilab, and they have been the premier event for calorimeter aficionados, a trend that CALOR2012 upheld. This year, several presentations focused on the status of the major calorimeter systems, especially at the LHC. Discussions on new and developing techniques in calorimetry took a full day. Excellent updates on uses of calorimeters or about ideas that are deeply rooted in particle physics calorimetry in astrophysics and neutrino physics were followed by talks on algorithms and special triggers that rely on calorimeters. Finally, discussions of promising current developments and ongoing R&D work for future calorimeters capped the conference. The field of calorimetry is alive and well, as evidenced by the more than 100 attendees and the excellent quality of over 80 presentations. You will find the written contributions in this volume. The presentations can be found at calor2012.ttu.edu. The first day of the conference was dedicated to the LHC. In two invited talks, Guillaume Unal (CERN) and Tommaso Tabarelli de Fatis (Universita' & INFN Milano Bicocca) discussed the critical role electromagnetic calorimeters play in the hunt for the Standard Model Higgs boson in ATLAS and CMS, respectively. The enhanced sensitivity for light Higgs in the two-gamma decay channel renders electromagnetic calorimeters indispensible. Much of the higher mass region was already excluded for the SM Higgs by the time of this conference, and after less than a month, on 4 July, CERN announced the discovery of a new boson at 125 GeV, a particle that seems consistent with the Higgs particle so far. Once again, without the electromagnetic calorimeters, this would not have been possible. Professor Geoffrey West from the Santa Fe Institute gave the keynote address. His talk, 'Universal Scaling Laws from Cells to Cities - a Physicist's Search for Quantitative, Unified Theories of Biological and Social Structure and Dynamics,' inspired many interesting questions from the audience both after the talk and throughout the week during informal conversations. Calorimetry is extremely diverse: many different techniques may be employed in building the detector and also in extracting information from it. The topics of the Calorimeter Techniques sessions included high-rate liquid argon calorimeters, SiPM sensors, highly granular digital calorimeters, new crystals, and beam test and simulation results. In these pages, you will find exciting and sometimes contradicting points of view expressed, for example about fully sampling hadronic calorimeters. A rare astronomical event, the Venus transit, coincided with the second day of the conference. The participants enjoyed viewing Venus' trail across the sun with a solar telescope (H-alpha line at 656 nm). In Santa Fe, the interior ingress was at 16:23:04 and reached center at 19:27:04. The last transit occurred in 2004, and the next one will happen in 2117. In 1627, Johannes Kepler published data about the planetary orbits that predicted that Venus would pass directly between earth and the sun in 1631. Unfortunately Kepler died in 1630 and apparently nobody recorded the 1631 transit. The first recorded observation of a transit was in 1638, which Kepler had not predicted. Later, Jeremiah Horracks, an English astronomer, realized Kepler had made an error in his calculations. It was not until the Venus transit observations of 1769 that scientists measured the distance from the earth to the sun to be 95 million miles (actually 93 million miles or 149.7 million kilometers) based on the 1716 triangulation suggestion from Edmund Halley (of comet fame). It's interesting to remember that before the 18th century, one of the most vexing scientific puzzles, not unlike today's Higgs boson quest, was 'How far away is the Sun?' Although natural media such as Mediterranean water (ANTARES), Arctic ice (ARA, ARIANNA, ANITA, and others)

Akchurin, Nural

2012-12-01

367

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

368

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

NASA Astrophysics Data System (ADS)

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

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

2015-04-01

369

Calorimetric and thermomechanical properties of titanium-based orthodontic wires: DSC-DMA relationship to predict the elastic modulus.  

PubMed

Orthodontic treatment is strongly dependent on the loads developed by metal wires, and the choice of an orthodontic archwire should be based on its mechanical performance. The desire of both orthodontists and engineers would be to predict the mechanical behavior of archwires. To this aim, Gum Metal (Toyota Central R&L Labs., Inc.), TMA (ORMCO), 35°C Copper NiTi (SDS ORMCO), Thermalloy Plus (Rocky Mountain), Nitinol SE (3M Unitek), and NiTi (SDS ORMCO) were tested according to dynamic mechanical analysis and differential scanning calorimetry. A model was also developed to predict the elastic modulus of superelastic wires. Results from experimental tests have highlighted that superelastic wires are very sensitive to temperature variations occurring in the oral environment, while the proposed model seems to be reliable to predict the Young's modulus allowing to correlate calorimetric and mechanical data. Furthermore, Gum Metal wire behaves as an elastic material with a very low Young's modulus, and it can be particularly useful for the initial stage of orthodontic treatments. PMID:21343211

Laino, Giuliana; De Santis, Roberto; Gloria, Antonio; Russo, Teresa; Quintanilla, David Suárez; Laino, Alberto; Martina, Roberto; Nicolais, Luigi; Ambrosio, Luigi

2012-03-01

370

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

371

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

ERIC Educational Resources Information Center

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

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

2007-01-01

372

Comparison of extracellular and net glucose oxidation measured isotopically and by indirect calorimetry during high and low glucose turnover  

SciTech Connect

To determine the extent to which glucose oxidation measured by indirect calorimetry reflects glucose oxidation measured isotopically, subjects were studied during a 6-h hyperinsulinemic euglycemic clamp (1 mU.kg-1.min-1) and during infusion of saline. (6-{sup 14}C)glucose was infused on both occasions. Breath was collected for determination of the specific activity of carbon dioxide, oxygen consumption, and carbon dioxide production. Glucose turnover during hyperinsulinemia was approximately eightfold higher than during saline infusion. During the final 1.5 h of the hyperinsulinemic glucose clamp, oxidation measured isotopically remained slightly but consistently lower (P less than 0.05) than that measured by indirect calorimetry (13.8 +/- 1.1 vs 16.5 +/- 1.7 mumol.kg-1.min-1, respectively). In contrast, during the saline infusion, glucose oxidation measured isotopically did not differ from that measured by indirect calorimetry (8.3 +/- 0.6 vs 7.2 +/- 2.8 mumol.kg-1.min-1, respectively). We conclude that although net glucose oxidation measured isotopically was slightly lower than that measured by indirect calorimetry, both techniques provide similar estimates of glucose oxidation over a wide range of glucose disposal.

McMahon, M.M.; Marsh, H.M.; Rizza, R.A. (Mayo Clinic, Rochester, MN (USA))

1991-05-01

373

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

374

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

375

Mechanistic overview of the curing behavior of hydride terminated polydimethylsiloxane with allyl functionalized alumina by calorimetry and rheometry  

Microsoft Academic Search

The study of the curing behavior of an encapsulation material is very important and critical in terms of understanding the properties of the material. Differential scanning calorimetry and rheometry are two important tools that have been utilized to study curing reactions in polymeric systems. The present work deals with the curing of a mixture of hydride terminated polydimethylsiloxane, allyl functionalized

Satyajit Gupta; Praveen C. Ramamurthy; Giridhar Madras

2011-01-01

376

Heat capacity and lattice dynamics of cubic and hexagonal SrMnO3 : Calorimetry and density functional theory simulations  

Microsoft Academic Search

The heat capacity and entropy of cubic and hexagonal SrMnO3 have been determined by relaxation calorimetry and by density functional theory. A main aim was to study the effect of temperature and thus entropy on the relative stability of corner versus face sharing of octahedra in perovskites. The results show that the heat capacity and thus the entropy of cubic

Rune Søndenå; Svein Stølen; P. Ravindran; Tor Grande

2007-01-01

377

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

378

A study of pyrolysis and pyrolysis products of flame-retardant cotton fabrics by DSC, TGA, and PY–GC–MS  

Microsoft Academic Search

Study of thermal decompositions of cotton and flame-retardant cotton fabrics can assist understanding of fire-resistant functions of the materials. In this research, differential scanning calorimeter (DSC), thermogravimetric analysis (TGA) and pyrolysis–gas chromatography–mass spectroscopy (PY–GC–MS) were employed to investigate decomposition processes and decomposed products of flame-retardant treated (using an organo-phosphorus compound) and untreated cotton fibers in the pyrolysis. The thermal decomposition

Ping Zhu; Shuying Sui; Bing Wang; Kai Sun; Gang Sun

2004-01-01

379

Alternative Calorimetry Based on the Photothermoelectric (PTE) Effect: Application to Magnetic Nanofluids  

NASA Astrophysics Data System (ADS)

Photothermoelectric (PTE) calorimetry was applied for the first time for thermal characterization of liquids. Both back and front detection configurations, together with the thermal-wave resonator cavity (TWRC) scanning procedure, have been used in order to measure the thermal diffusivity and thermal effusivity of a particular magnetic nanofluid: carrier liquid—transformer oil, surfactant—oleic acid, nanoparticles' type—hbox {Fe}3hbox {O}4 .The investigations were performed as a function of the nanoparticles' concentration. Small increases of thermal diffusivity (from 9.06× 10^{-8} hbox {m}2{\\cdot } hbox {s}^{-1} up to 9.84× 10^{-8} hbox {m}2{\\cdot } hbox {s}^{-1}) and thermal effusivity (from 450 hbox {W}{\\cdot } hbox {s}^{1/2}{\\cdot } hbox {m}^{-2}{\\cdot } hbox {K}^{-1} up to 520 hbox {W}{\\cdot } hbox {s}^{1/2}{\\cdot } hbox {m}^{-2}{\\cdot } hbox {K}^{-1}) with increasing concentration of hbox {Fe}3hbox {O}4 nanoparticles (from 0 up to 0.623 mg hbox {Fe}3hbox {O}4/hbox {ml} fluid) were observed. The comparison with the photopyroelectric (PPE) method shows that PTE and PPE give similar results but, for the moment, PPE is more accurate.

Dadarlat, Dorin; Misse, Patrick R. N.; Maignan, Antoine; Guilmeau, Emmanuel; Turcu, Rodica; Vekas, Ladislau; Tudoran, Cristian; Depriester, Michael; Sahraoui, Abdelhak Hadj

2015-03-01

380

Beam studies of the segmented resistive WELL: A potential thin sampling element for digital hadron calorimetry  

NASA Astrophysics Data System (ADS)

Thick Gas Electron Multipliers (THGEMs) have the potential of constituting thin, robust sampling elements in Digital Hadron Calorimetry (DHCAL) at future colliders. We report on recent beam studies of new single- and double-THGEM-like structures: the multiplier is a Segmented Resistive WELL (SRWELL) - a single-faced THGEM in contact with a segmented resistive layer inductively coupled to readout pads. Several 10×10 cm2 configurations with a total thickness of 5-6 mm (excluding electronics) with 1 cm2 pads were investigated with muons and pions. The pads were coupled to a scalable readout system APV chip, APV-SRS (Raymond et al. [22]). Detection efficiencies in the 98% range were recorded with an average pad-multiplicity of ~1.1. The resistive anode resulted in efficient discharge damping, with potential drops of a few volts; the discharge probabilities were ~10-7 for muons and ~10-6 for pions, at rates of a few kHz/cm2 and for detectors in the double-stage configuration. Further optimization work and research on larger detectors are underway.

Arazi, Lior; Davide Rocha Azevedo, Carlos; Breskin, Amos; Bressler, Shikma; Moleri, Luca; Natal da Luz, Hugo; Oliveri, Eraldo; Pitt, Michael; Rubin, Adam; Marques Ferreira dos Santos, Joaquim; Filipe Calapez de Albuquerque Veloso, João; Paul White, Andrew

2013-12-01

381

Assessment of porosities of SBA-15 and MCM-41 using water sorption calorimetry.  

PubMed

Water sorption calorimetry has been used for characterization of 2D hexagonally ordered mesoporous silica SBA-15. Experimental data on water sorption isotherm, the enthalpy, and the entropy of hydration of SBA-15 are presented. The results were compared with previously published results on MCM-41 obtained using the same technique. The water sorption isotherm of SBA-15 consists of four regimes, while the sorption isotherm of MCM-41 consists only of three. The extra regime in the water sorption isotherm for SBA-15 arises from filling of intrawall pores, that are present in SBA-15 but absent in MCM-41. The water sorption isotherms of the two types of mesoporous silica were analyzed using the Barrett-Joyner-Halenda approach. For the BJH analysis, t-curves of silica with different degrees of hydroxylation were proposed. Comparison of water and nitrogen t-curves shows that, independent of hydroxylation of silica surface, the adsorbed film of water is much thinner than the adsorbed film of nitrogen at similar relative pressures. This fact decreases the uncertainty of the assessment of porosity with water sorption originated from variations in surface properties. The pore size distribution of SBA-15 calculated with BJH treatment of water sorption data is in good agreement with nitrogen NLDFT results on the same material. PMID:21366316

Kocherbitov, Vitaly; Alfredsson, Viveka

2011-04-01

382

Probing the binding of procyanidin B3 to human serum albumin by isothermal titration calorimetry  

NASA Astrophysics Data System (ADS)

Proanthocyanidins are a mixture of monomers, oligomers, and polymers of flavan-3-ols that are widely distributed in the plant kingdom. One of the most widely studied proanthocyanidins is procyanidin B3. In this study, the interaction between procyanidin B3 and human serum albumin (HSA) was investigated using isothermal titration calorimetry (ITC). Thermodynamic investigations reveal that the hydrogen bond and van der Waals force are the major binding forces in the binding of procyanidin B3 to HSA. The binding of procyanidin B3 to HSA is driven by favorable enthalpy and unfavorable entropy. The obtained binding constant for procyanidin B3 with HSA is in the intermediate range and the equilibrium fraction of unbound procyanidin B3 fu > 90% at the physiological concentration of HSA shows that procyanidin B3 can be stored and transported from the circulatory system to reach its target site. The stoichiometric binding number n approximately equals to 1, suggesting that one molecule of procyanidin B3 combines with one molecule of HSA and no more procyanidin B3 binding to HSA occurs at the concentration used in this study.

Li, Xiangrong; Yan, Yunhui

2015-02-01

383

Thermodynamic analysis of Bacillus subtilis endospore protonation using isothermal titration calorimetry  

NASA Astrophysics Data System (ADS)

Bacterial proton and metal adsorption reactions have the capacity to affect metal speciation and transport in aqueous environments. We coupled potentiometric titration and isothermal titration calorimetry (ITC) analyses to study Bacillus subtilis spore-proton adsorption. We modeled the potentiometric data using a four and five-site non-electrostatic surface complexation model (NE-SCM). Heats of spore surface protonation from coupled ITC analyses were used to determine site specific enthalpies of protonation based on NE-SCMs. The five-site model resulted in a substantially better model fit for the heats of protonation but did not significantly improve the potentiometric titration model fit. The improvement observed in the five-site protonation heat model suggests the presence of a highly exothermic protonation reaction circa pH 7 that cannot be resolved in the less sensitive potentiometric data. From the log Ks and enthalpies we calculated corresponding site specific entropies. Log Ks and site concentrations describing spore surface protonation are statistically equivalent to B. subtilis cell surface protonation constants. Spore surface protonation enthalpies, however, are more exothermic relative to cell based adsorption suggesting a different bonding environment. The thermodynamic parameters defined in this study provide insight on molecular scale spore-surface protonation reactions. Coupled ITC and potentiometric titrations can reveal highly exothermic, and possibly endothermic, adsorption reactions that are overshadowed in potentiometric models alone. Spore-proton adsorption NE-SCMs derived in this study provide a framework for future metal adsorption studies.

Harrold, Zoë R.; Gorman-Lewis, Drew

2013-05-01

384

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

NASA Astrophysics Data System (ADS)

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

Cavan, A.; Meyer, J.

2013-06-01

385

Quantitative Absorption and Kinetic Studies of Transient Species Using Gas Phase Optical Calorimetry  

NASA Astrophysics Data System (ADS)

Quantitative measurements of the absorption cross-sections and reaction rates constants of free radicals by spectroscopic means requires the knowledge of the absolute concentration of the target species. We have demonstrated earlier that such information can be retrieved from absorption measurements of the well-known ``reporter" molecule, co-produced in radical synthesis. This method is limited to photochemical protocols allowing for production of ``reporters" stochiometrically with the target species. This limitation can be overcome by use of the optical calorimetry (OC) which measures heat signatures of a photochemical protocol. These heat signatures are directly related to the amount of species produced and the thermochemical data of the reactants and stable products whose accuracy is usually substantially higher than that of the absorption data for prospective ``reporters". The implementation of the OC method presented in this talk is based on the measurements of the frequency shift of the resonances due to the change in the optical density of the reactiove sample within a Fabry-Perot cavity caused by deposition of heat from the absorbed photolysis beam and subsequent chemical reactions. Preliminary results will be presented and future development of this experimental technique will be discussed. D. Melnik, R. Chhantyal-Pun and T. A. Miller, J. Phys. Chem. A, 114, 11583, (2010)

Melnik, Dmitry G.

2014-06-01

386

Lipid domains in the ram sperm plasma membrane demonstrated by differential scanning calorimetry.  

PubMed Central

Mammalian sperm plasma membranes, in contrast to those of mammalian somatic cells, exhibit a significant fraction of lipid that does not diffuse laterally in the plane of the membrane. This nondiffusing fraction results from lipid-lipid interactions. Similar nondiffusing fractions are found in mixed-lipid model systems that contain coexistent gel and fluid domains. These results suggest that the sperm plasma membrane may also exhibit lateral phase segregations of lipids and may contain significant amounts of gel-phase lipid. In this paper we use differential scanning calorimetry to show that, in contrast to the plasma membranes of mammalian somatic cells, the plasma membrane from the anterior region of the head of ram sperm exhibits at least two major endothermic transitions, one centered at approximately 26 degrees C and one centered at approximately 60 degrees C. The heats of these transitions are consistent with gel-to-fluid transitions in model membranes. These transitions are observed both in plasma membrane vesicles and in rehydrated lipid extracts made from these vesicles. These results demonstrate that at physiological temperatures the lipids of the ram sperm plasma membrane are segregated into coexistent fluid and gel domains. Since sperm encounter a wide range of temperatures during their development, these phase transitions may be important in establishing dynamic domains of lipid requisite for epididymal storage and fertilization. PMID:2395884

Wolf, D E; Maynard, V M; McKinnon, C A; Melchior, D L

1990-01-01

387

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

PubMed

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

Li, Xiangrong; Yang, Zhenhua

2015-05-01

388

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

PubMed

Isothermal titration calorimetry (ITC) has become the gold-standard technique for studying binding processes due to its high precision and sensitivity, as well as its capability for the simultaneous determination of the association equilibrium constant, the binding enthalpy and the binding stoichiometry. The current widespread use of ITC for biological systems has been facilitated by technical advances and the availability of commercial calorimeters. However, the complexity of data analysis for non-standard models is one of the most significant drawbacks in ITC. Many models for studying macromolecular interactions can be found in the literature, but it looks like each biological system requires specific modeling and data analysis approaches. The aim of this article is to solve this lack of unity and provide a unified methodological framework for studying binding interactions by ITC that can be applied to any experimental system. The apparent complexity of this methodology, based on the binding polynomial, is overcome by its easy generalization to complex systems. PMID:25305413

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

2015-04-01

389

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

SciTech Connect

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

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

2008-01-01

390

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

PubMed Central

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

2013-01-01

391

Sub-picowatt resolution calorimetry with niobium nitride thin-film thermometer  

SciTech Connect

High-resolution calorimetry has many important applications such as probing nanoscale thermal transport and studying the thermodynamics of biological and chemical systems. In this work, we demonstrated a calorimeter with an unprecedentedly high resolution at room temperature using a high-performance resistive thermometry material, niobium nitride (NbN{sub x}). Based on a theoretical analysis, we first showed that the heat flux resolution of a resistive-thermometry based calorimeter depends on the parasitic thermal conductance of the device and the temperature coefficient of resistance (TCR) of the thermometer, when the noise is limited by the Johnson noise. Based on this analysis, we then developed a calorimeter using NbN{sub x} as the thermometry material because it possesses both high TCR (?0.67%/K) and a low thermal conductivity (k ? 1.1 W/m?K). This calorimeter, when used with the modulated heating scheme, demonstrated an unprecedentedly high power resolution of 0.26 pW at room temperature. In addition, NbN{sub x} based resistive thermometry can also be extended to cryogenic temperature, where the TCR is shown to be significantly higher.

Dechaumphai, Edward; Chen, Renkun, E-mail: rkchen@ucsd.edu [Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California 92093 (United States)

2014-09-15

392

Sub-picowatt resolution calorimetry with niobium nitride thin-film thermometer.  

PubMed

High-resolution calorimetry has many important applications such as probing nanoscale thermal transport and studying the thermodynamics of biological and chemical systems. In this work, we demonstrated a calorimeter with an unprecedentedly high resolution at room temperature using a high-performance resistive thermometry material, niobium nitride (NbN(x)). Based on a theoretical analysis, we first showed that the heat flux resolution of a resistive-thermometry based calorimeter depends on the parasitic thermal conductance of the device and the temperature coefficient of resistance (TCR) of the thermometer, when the noise is limited by the Johnson noise. Based on this analysis, we then developed a calorimeter using NbNx as the thermometry material because it possesses both high TCR (~0.67%/K) and a low thermal conductivity (k ~ 1.1 W/m?K). This calorimeter, when used with the modulated heating scheme, demonstrated an unprecedentedly high power resolution of 0.26 pW at room temperature. In addition, NbNx based resistive thermometry can also be extended to cryogenic temperature, where the TCR is shown to be significantly higher. PMID:25273760

Dechaumphai, Edward; Chen, Renkun

2014-09-01

393

Sub-picowatt resolution calorimetry with niobium nitride thin-film thermometer  

NASA Astrophysics Data System (ADS)

High-resolution calorimetry has many important applications such as probing nanoscale thermal transport and studying the thermodynamics of biological and chemical systems. In this work, we demonstrated a calorimeter with an unprecedentedly high resolution at room temperature using a high-performance resistive thermometry material, niobium nitride (NbNx). Based on a theoretical analysis, we first showed that the heat flux resolution of a resistive-thermometry based calorimeter depends on the parasitic thermal conductance of the device and the temperature coefficient of resistance (TCR) of the thermometer, when the noise is limited by the Johnson noise. Based on this analysis, we then developed a calorimeter using NbNx as the thermometry material because it possesses both high TCR (˜0.67%/K) and a low thermal conductivity (k ˜ 1.1 W/m K). This calorimeter, when used with the modulated heating scheme, demonstrated an unprecedentedly high power resolution of 0.26 pW at room temperature. In addition, NbNx based resistive thermometry can also be extended to cryogenic temperature, where the TCR is shown to be significantly higher.

Dechaumphai, Edward; Chen, Renkun

2014-09-01

394

Structural origin of fragility in ge-as-s glasses investigated by calorimetry and Raman spectroscopy.  

PubMed

The fragility index (m) of a series of Ge-As-S glasses covering a wide range of mean coordination (?r?) and stoichiometry is measured by differential scanning calorimetry. The evolution of the fragility index appears to be better predicted by the stoichiometry than the mean coordination, and m shows a well-defined dependence on the departure from stoichiometry quantified as the at. % excess or deficiency in sulfur. The effect of stoichiometry on the fragility of Ge-As-S glasses is very similar to that observed in the Ge-As-Se system. A systematic Raman spectroscopy investigation also indicates the presence of large fractions of molecular species such as S8, As4S4, and As4S3 in the structure of some glasses. The presence of molecular species is shown to increase the fragility and decrease the glass transition temperature (Tg). These results emphasize that short-range order rather than long-range characteristics such as structural rigidity appears to control the fragility of chalcogenide glasses. PMID:25806831

Yang, Yan; Zhang, Bin; Yang, Anping; Yang, Zhiyong; Lucas, Pierre

2015-04-16

395

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

PubMed Central

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

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

2011-01-01

396

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

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

397

Plutonium assay for safeguards purposes: Material heterogeneity and the application of calorimetry  

SciTech Connect

Quantitative assays of plutonium materials are required for place operations and domestic and international nuclear material accounting. These assays have typically been made using destructive analysis techniques (weighing and chemical and isotopic concentration measurements). However,, nondestructive assay techniques based on combined gamma isotopic and calorimeter measurements have appear because they are rapid (compared with sampling and destructive analysis), accurate, and require no sampling. In addition, the nondestructive techniques reduce contamination risks, waste generation, and radiological dose. Measurement variabilities for destructive analysis and nondestructive assay techniques have been compiled for some pure and scrap plutonium oxide items. These items are under International Atomic Energy Agency safeguards in the Plutonium Finishing Plant operated for the US Department of Energy by the Westinghouse Hanford Company. Measurement variabilities of International Atomic Energy Agency and Westinghouse Hanford Company destructive analysis methods were compared with Westinghouse Hanford Company calorimeter variability. Total measurement variabilities for calorimetry were comparable with the combined sampling and analytical variabilities of chemical analyses for pure materials and were lower for heterogeneous scrap.

Welsh, T.L.; Delegard, C.H.; Hamilton, R.A. [Westinghouse Hanford Co., Richland, WA (United States)] [and others

1996-12-31

398

Effect of temperature on studtite stability: Thermogravimetry and differential scanning calorimetry investigations  

NASA Astrophysics Data System (ADS)

The main objective of this work is the study of the influence of temperature on the stability of the uranyl peroxide tetrahydrate (UO 2O 2 · 4H 2O) studtite, which may form on the spent nuclear fuel surface as a secondary solid phase. Preliminary results on the synthesis of studtite in the laboratory at different temperatures have shown that the solid phases formed when mixing hydrogen peroxide and uranyl nitrate depends on temperature. Studtite is obtained at 298 K, meta-studtite (UO 2O 2 · 2H 2O) at 373 K, and meta-schoepite (UO 3 · nH 2O, with n < 2) at 423 K. Because of the temperature effect on the stability of uranyl peroxides, a thermogravimetric (TG) study of studtite has been performed. The main results obtained are that three transformations occur depending on temperature. At 403 K, studtite transforms to meta-studtite, at 504 K, meta-studtite transforms to meta-schoepite, and, finally, at 840 K, meta-schoepite transforms to U 3O 8. By means of the differential scanning calorimetry the molar enthalpies of the transformations occurring at 403 and 504 K have been determined to be -42 ± 10 and -46 ± 2 kJ mol -1, respectively.

Rey, A.; Casas, I.; Giménez, J.; Quiñones, J.; de Pablo, J.

2009-03-01

399

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

SciTech Connect

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

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

2009-07-31

400

High-Precision Isothermal Titration Calorimetry with Automated Peak Shape Analysis  

PubMed Central

Isothermal titration calorimetry (ITC) is a powerful classical method that enables researchers in many fields to study the thermodynamics of molecular interactions. Primary ITC data comprise the temporal evolution of differential power reporting the heat of reaction during a series of injections of aliquots of a reactant into a sample cell. By integration of each injection peak, an isotherm can be constructed of total changes in enthalpy as a function of changes in solution composition, which is rich in thermodynamic information on the reaction. However, the signals from the injection peaks are superimposed by the stochastically varying time-course of the instrumental baseline power, limiting the precision of ITC isotherms. Here, we describe a method for automated peak assignment based on peak-shape analysis via singular value decomposition in combination with detailed least-squares modeling of local pre- and post-injection baselines. This approach can effectively filter out contributions of short-term noise and adventitious events in the power trace. This method also provides, for the first time, statistical error estimates for the individual isotherm data points. In turn, this results in improved detection limits for high-affinity or low-enthalpy binding reactions and significantly higher precision of the derived thermodynamic parameters. PMID:22530732

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

2012-01-01

401

Characterization of carbon monoxide photodissociation from Fe(II)LPO with photoacoustic calorimetry.  

PubMed

Lactoperoxidase belongs to a family of mammalian peroxidases that catalyze the oxidation of halides and small organic molecules in the presence of H2O2. We have used photoacoustic calorimetry to characterize thermodynamic parameters associated with ligand dissociation from bovine milk lactoperoxidase. Upon CO photorelease, a prompt (tau < 50 ns) exothermic volume contraction (DeltaH = -20 +/- 7 kcal mol-1 and DeltaH = -2 +/- 1 mL mol-1) was measured at pH 7.0 and 4.0, whereas an endothermic expansion (DeltaH = 30 +/- 13 kcal mol-1 and DeltaV = 9 +/- 2 mL mol(-1)) was observed at pH 10.0 and 7.0 in the presence of 500 mM NaCl. We attribute the observed volume and enthalpy changes to electrostriction arising from changes in the charge distribution associated with a reorganization of the heme binding pocket upon ligand dissociation. It is likely that cleavage of the Fe-CO bond is accompanied by distortion of a salt bridge between Arg557 and the heme propionate group, resulting in the observed electrostriction due to changes in charge distribution. PMID:17125388

Lockney, Dustin; Miksovská, Jaroslava

2006-11-30

402

Energetics of genome ejection from phage revealed by isothermal titration calorimetry  

NASA Astrophysics Data System (ADS)

It has been experimentally shown that ejection of double-stranded DNA from phage is driven by internal pressure reaching tens of atmospheres. This internal pressure is partially responsible for delivery of DNA into the host cell. While several theoretical models and simulations nicely describe the experimental data of internal forces either resisting active packaging or equivalently favoring spontaneous ejection, there are no direct energy measurements available that would help to verify how quantitative these theories are. We performed direct measurements of the enthalpy responsible for DNA ejection from phage ?, using Isothermal Titration Calorimetry. The phage capsids were ``opened'' in vitro by titrating ? into a solution with LamB receptor and the enthalpy of DNA ejection process was measured. In his way, enthalpy stored in ? was determined as a function of packaged DNA length comparing wild-type phage ? (48.5 kb) with a shorter ?-DNA length mutant (37.7 kb). The temperature dependence of the ejection enthalpy was also investigated. The values obtained were in good agreement with existing models and provide a better understanding of ds- DNA packaging and release mechanisms in motor-packaged viruses (e.g., tailed bacteriophages, Herpes Simplex, and adenoviruses).

Jeembaeva, Meerim; Jonsson, Bengt; Castelnovo, Martin; Evilevitch, Alex

2009-03-01

403

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

SciTech Connect

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

Xiao, Kechao; Lee, Dongwoo; Vlassak, Joost J., E-mail: vlassak@esag.harvard.edu [School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, Massachusetts 02138 (United States)

2014-10-27

404

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

405

Crystallization kinetics of a bulk amorphous Cu–Ti–Zr–Ni alloy investigated by differential scanning calorimetry  

Microsoft Academic Search

The crystallization kinetics of a newly developed bulk amorphous Cu52.5Ti30Zr11.5Ni6 alloy was investigated by differential scanning calorimetry. Under continuous heating conditions, the activation energies for the glass transition and crystallization at the onset, first peak and second peak crystallization temperatures are determined by means of Kissinger plots to be 356.86, 296.52, 288.77 and 257.19kJ\\/mol, respectively. However, under isothermal conditions the

Y. J. Yang; D. W. Xing; J. Shen; J. F. Sun; S. D. Wei; H. J. He; D. G. McCartney

2006-01-01

406

Comparison of Short Term Indirect Calorimetry and Doubly Labeled Water Method for the Assessment of Energy Expenditure in Preterm Infants  

Microsoft Academic Search

The accuracy of 8-hour indirect calorimetry (IDC) as an estimate of energy expenditure was investigated in 8 healthy preterm infants (birth weight 1,270 ± 193 g, gestational age 32 ± 3 weeks, mean ± SD) in comparison with an analysis over 5 days using the doubly-labeled water (2H218O) method (DLW). The infants that were fed continuously by nasogastric drip with

Klaas R. Westerterp; Harry N. Lafeber; Eric J. Sulkers; Pieter J. Sauer

1991-01-01

407

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

Microsoft Academic Search

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

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

408

Effects of Modulated Differential Scanning Calorimetry (MDSC) Variables on Thermodynamic and Kinetic Characteristics During Gelatinization of Waxy Rice Starch 1  

Microsoft Academic Search

Cereal Chem. 76(4):519-525 The total, reversing, and nonreversing thermal properties during gela- tinization of waxy rice starch (starch-to-water ratio = 1:2, w\\/w) were examined by modulated differential scanning calorimetry (MDSC). The effect of MDSC operating variables (i.e., the amplitude and frequency of temperature modulation and the underlying heating rate) on these thermal properties was determined by response surf ace methodology

Vivian M.-F. Lai; Cheng-Yi Lii

1999-01-01

409

Characterizing water/rock interaction in simulated comet nuclei via calorimetry: Tool for in-situ science, laboratory analysis, and sample preservation  

NASA Technical Reports Server (NTRS)

Although results from the Giotto and Vega spacecraft flybys of comet P/Halley indicate a complex chemistry for both the ices and dust in the nucleus, carbonaceous chondrite meteorites are still regarded as useful analogs for the rocky components. Carbonaceous chondrites mixed with water enable simulation of water/rock interactions which may occur in cometary nuclei. Three general types of interactions can be expected between water and minerals at sub-freezing temperatures: heterogeneous nucleation of ice by insoluble minerals; adsorption of water vapor by hygroscopic phases; and freezing and melting point depression of liquid water sustained by soluble minerals. Two series of experiments were performed in a differential scanning calorimeter (DSC) with homogenized powders of the following whole-rock meteorites and comparison samples: Allende (CV3), Murchison (CM2), Orgueil (CI), Holbrook (L6), and Pasamonte (eucrite) meteorites as well as on peridotite (PCC-1, USGS), saponite (Sap-Ca-1, CMS), montmorillonite (STx-1, CMS), and serpentine (Franciscan Formation, California). Results are briefly discussed.

Allton, Judith H.; Gooding, James L.

1991-01-01

410

31P NMR and isothermal titration calorimetry studies on polyoxomolybdates-catalyzed hydrolysis of ATP.  

PubMed

ATP hydrolysis in the presence of polyoxomolybdates at pH levels of 6, 4, and 2 has been investigated with a help of high pressure liquid chromatography (HPLC) analyses, 31P- and 1H NMR measurements, and isothermal titration calorimetry (ITC). The polyoxomolybdates-induced ATP-hydrolysis proceeded satisfactorily in pH < 6 media at 20 degrees C with an optimum pH level of 4, while it was significantly depressed at low temperature of < or = 5 degrees C. At pH levels of 6 and 4, ADP was a main product, and the involvement of [(PO4)2Mo5O15](6-)-like ATP-molybdate complex as an intermediate was implied. At pH 2 ATP was decomposed to AMP with small generation of ADP through the formation of the ATP-molybdate complex isostructural with [(O3POPO3)Mo6O18(H2O)4]4- as an intermediate. The ITC result at pH 4 showed an occurrence of two types of the exothermic binding reactions between molybdate and ATP with binding constants (K) of 6.61x10(4) and 9.40x10(3) M(-1) and molar enthalpy values (deltaH) of -6.32x10(4) and -4.73x10(3) J mol(-1), respectively. Together with the results of 1H NMR measurements, it is deduced that the molybdates interact with not only phosphate sites in the ATP side-chain, but also adenine-ring with an accompanying aggregation of molybdates at pH 4. PMID:16403572

Ishikawa, Eri; Yamase, Toshihiro

2006-03-01

411

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

SciTech Connect

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

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

2014-02-15

412

Global analysis of riboswitches by small-angle X-ray scattering and calorimetry.  

PubMed

Riboswitches are phylogenetically widespread non-coding mRNA domains that directly bind cellular metabolites and regulate transcription, translation, RNA stability or splicing via alternative RNA structures modulated by ligand binding. The details of ligand recognition by many riboswitches have been elucidated using X-ray crystallography and NMR. However, the global dynamics of riboswitch-ligand interactions and their thermodynamic driving forces are less understood. By compiling the work of many laboratories investigating riboswitches using small-angle X-ray scattering (SAXS) and isothermal titration calorimetry (ITC), we uncover general trends and common themes. There is a pressing need for community-wide consensus experimental conditions to allow results of riboswitch studies to be compared rigorously. Nonetheless, our meta-analysis reveals considerable diversity in the extent to which ligand binding reorganizes global riboswitch structures. It also demonstrates a wide spectrum of enthalpy-entropy compensation regimes across riboswitches that bind a diverse set of ligands, giving rise to a relatively narrow range of physiologically relevant free energies and ligand affinities. From the strongly entropy-driven binding of glycine to the predominantly enthalpy-driven binding of c-di-GMP to their respective riboswitches, these distinct thermodynamic signatures reflect the versatile strategies employed by RNA to adapt to the chemical natures of diverse ligands. Riboswitches have evolved to use a combination of long-range tertiary interactions, conformational selection, and induced fit to work with distinct ligand structure, charge, and solvation properties. This article is part of a Special Issue entitled: Riboswitches. PMID:24769285

Zhang, Jinwei; Jones, Christopher P; Ferré-D'Amaré, Adrian R

2014-10-01

413

Ind Cd ADAP AENR ALL ATH CENR CIS CSH DPL DSC ECHEK ENVER FALL GRD HS ID LIB NLATE NOB PAYPL REF TRN A01 High School Transcript Hold X X X X X X X  

E-print Network

Srv Ind Cd ADAP AENR ALL ATH CENR CIS CSH DPL DSC ECHEK ENVER FALL GRD HS ID LIB NLATE NOB PAYPL student CIS Computer Site Services PAYPL Payment Plan DPL Diploma ­ Issuance of REF Refunds ­ Issuance

Jiang, Huiqiang

414

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

PubMed Central

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

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

1995-01-01

415

The Effect of Pulse Sequence Parameters and Contrast Agent Dose on Percentage Signal Recovery in DSC-MRI: Implications for Clinical Applications  

PubMed Central

BACKGROUND AND PURPOSE Both technical and pathophysiologic factors affect PSR in DSC-MR imaging. We aimed to determine how TE, flip angle (?), and contrast dose impact PSR in high-grade gliomas. MATERIALS AND METHODS We retrospectively computed PSR maps for 22 patients with high-grade gliomas, comparing 3 DSC-MR imaging methods by using single-dose gadodiamide without preload administration: A (n = 7), ? = 35°, TE = 54 ms; B (n = 5), ? = 72°, TE = 30 ms; C (n = 10), ? = 90°, TE = 30 ms. Methods A–C served as preload for subsequent dynamic imaging using method D (method C parameters but with double-dose contrast). We compared first- and second-injection tumor PSR for methods C and D (paired t test) and tumor PSR for both injections grouped by the first-injection acquisition method (3-group nonparametric 1-way ANOVA). We compared PSR in tumor and normal brain for each first- and second-injection method group (paired t test). RESULTS First-injection PSR in tumor and normal brain differed significantly for methods B (P = .01) and C (P = .05), but not A (P = .71). First-injection tumor PSR increased with T1 weighting with a significant main effect of method groupings (P = .0012), but there was no significant main effect for first-injection normal brain (P = .93), or second-injection tumor (P = .95) or normal brain (P = .13). In patients scanned with methods C and D, first-injection PSR significantly exceeded second-injection PSR for tumor (P = .037) and normal brain (P < .001). CONCLUSIONS PSR strongly depends on the T1 weighting of DSC-MR imaging, including pulse sequence (TE, ?) and contrast agent (dose, preload) parameters, with implications for protocol design and the interpretation and comparison of PSR values across tumor types and imaging centers. PMID:23413249

Boxerman, J.L.; Paulson, E.S.; Prah, M.A.; Schmainda, K.M.

2014-01-01

416

Use of DSC and DMA to Study Rubber Crystallization as a Possible Cause for a Tear in a Neoprene Glove Used in a Space Shuttle Pressurized Astronaut Suit  

NASA Technical Reports Server (NTRS)

The Advanced Crew Escape Suit (ACES) is a pressurized suit normally worn by astronauts during launch and landing phases of Space Shuttle operations. In 2008, a large tear (0.5 -1 in. long, between the pinky and ring finger) in the ACES left-hand glove made of neoprene latex rubber was found during training for Shuttle flight STS-124. An investigation to help determine the cause(s) of the glove tear was headed by the NASA Johnson Space Center (JSC) in Houston, Texas. Efforts at JSC to reproduce the actual glove tear pattern by cutting/tearing or rupturing were unsuccessful. Chemical and material property data from JSC such as GC-MS, FTIR, DSC and TGA mostly showed little differences between samples from the torn and control gloves. One possible cause for the glove tear could be a wedding ring/band worn by a male astronaut. Even with a smooth edge, such a ring could scratch the material and initiate the tear observed in the left-hand glove. A decision was later made by JSC to not allow the wearing of such a ring during training or actual flight. Another possible cause for the ACES glove tear is crystallinity induced by strain in the neoprene rubber over a long period of time and use. Neoprene is one several elastomeric materials known to be susceptible to crystallization, and such a process is accelerated with exposure of the material to cold temperatures plus strain. When the temperature is lowered below room temperature, researchers have shown that neoprene crystallization may be maintained at temperatures as high as 45-50 F, with a maximum crystallization rate near 20-25 F (1). A convenient conditioning temperature for inducing neoprene crystallization is a typical freezer that is held near 0 F. For work at the NASA Marshall Space Flight Center (MSFC), samples were cut from several areas/locations (pinky/ring finger crotch, index finger and palm) on each of two pairs of unstrained ACES gloves for DSC and DMA thermal analysis testing. The samples were conditioned in a freezer for various times up to about 14 days. Some rectangular conditioned samples were unstrained, while most were subjected to strains up to 250% with the aid of two slotted aluminum blocks and two aluminum clamps per sample. Trends were observed to correlate DSC data (heat of fusion) and DMA data (linear CTE and stress for iso-strain testing) with: (a) sample location on each glove; and (b) level of strain during conditioning. Control samples cut as is from each glove location were also tested by DSC and DMA.

Wingard, Doug

2009-01-01

417

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

NASA Astrophysics Data System (ADS)

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

Barbosa, Silvia; Taboada, Pablo; Mosquera, Victor

2005-04-01

418

A compact low-temperature single crystal adsorption calorimetry setup for measuring coverage dependent heats of adsorption at cryogenic temperatures  

NASA Astrophysics Data System (ADS)

Here we present the modification of an already existing Single Crystal Adsorption Calorimetry (SCAC) apparatus which has been extended by a compact cooling system to measure the coverage dependent heats of adsorption of gaseous compounds on thin metal substrates in a temperature range from 80 K to 430 K. The setup is characterized and its performance is tested by studying the adsorption of CO on Pt(111) at 150 K and 300 K. Coverage dependent sticking probabilities and heat of adsorption measurements are compared to previous experimental and theoretical studies proving the reliability of our compact low-temperature-SCAC setup.

Hörtz, Peter; Schäfer, Rolf

2014-07-01

419

Specific Heat Capacities of Sn-Zn-Based Solders and Sn-Ag-Cu Solders Measured Using Differential Scanning Calorimetry  

Microsoft Academic Search

The specific heat capacities (C\\u000a p) of Sn-Zn-based solders and Sn-Ag-Cu solders have been studied using differential scanning calorimetry. The procedure of\\u000a measuring the specific heat capacity followed the standard test method designed by the American Society for Testing and Materials\\u000a (ASTM) E1269-05. The results of this work are lists of specific heat capacities of Sn-9Zn, Sn-9Zn-xAg (x = 0.1, 0.5, 1,

Y. K. Wu; K. L. Lin; B. Salam

2009-01-01

420

Enthalpy of formation of talc Mg3[Si4O10](OH)2 according to dissolution calorimetry  

NASA Astrophysics Data System (ADS)

A thermochemical study of natural talc was performed by high-temperature melt dissolution calorimetry on a Tian-Calvet calorimeter. Based on the total values of the increment in enthalpy upon heating the sample from room temperature to 973 K, and of the dissolution enthalpy at 973 K measured in this work for talc and gibbsite (along with those determined for tremolite, brucite, and their corresponding oxides), the enthalpy of formation was calculated for talc composed of elements, Mg3[Si4O10](OH)2, at 298.15 K: ?f H {el/o}(298.15 K) = -5900.6 ± 4.7 kJ/mol.

Ogorodova, L. P.; Kiseleva, I. A.

2011-09-01

421

Temperature-modulated calorimetry of the frequency dependence of the glass transition of poly(ethylene terephthalate) and ....  

SciTech Connect

Temperature-modulated differential scanning calorimetry, TMDSC, is new technique that permits to measure the apparent heat capacity vs modulation frequency. The method is briefly described and a quasi- isothermal measurement method is used to derive the kinetic parameters for PET and PS. A first-order kinetics expression was used to describe the approach to equilibrium and point out the limits caused by asymmetry and cooperativity of the kinetics. Use of a complex description of heat capacity and entropy is discussed. Activation energies vary from 75 to 350 kJ/mol, dependent on thermal pretreatment and the preexponential factor is correlated with the activation energy.

Wunderlich, B.; Okazaki, I. [Oak Ridge National Lab., TN (United States)] [Tennessee Univ., Knoxville, TN (United States). Dept. of Chemistry

1997-03-01

422

Particle Size (Sieving) and Enthalpy (Acid Calorimetry) Analysis of Single-Pull K East Basin Floor and Pit Sludges  

SciTech Connect

This report discusses particle size and calorimetry analyses performed on single-pull sludge samples collected from the Hanford K East Basin floor and pits. This study was conducted by the Pacific Northwest National Laboratory (PNNL) in support of the baseline sludge management plan, which calls for the sludge to be packaged, shipped and stored at T Plant in the Hanford 200 West Area until final processing as a future date. These analyses were needed to better understand the K Basin sludge inventory and chemical reactivity.

Bredt, Paul R. (BATTELLE (PACIFIC NW LAB)); Delegard, Calvin H. (BATTELLE (PACIFIC NW LAB)); Schmidt, Andrew J. (BATTELLE (PACIFIC NW LAB)); Silvers, Kurt L. (BATTELLE (PACIFIC NW LAB)); Thornton, Brenda M. (BATTELLE (PACIFIC NW LAB)); Gano, Sue (BATTELLE (PACIFIC NW LAB))

2000-10-31

423

Development of crystal scintillators for calorimetry in high energy and astroparticle physics  

NASA Astrophysics Data System (ADS)

Here we describe application of the low-thermal gradient Chozchralski method to grow high quality radiopure cadmium tungstate crystal scintillators from enriched isotopes 106Cd and 116Cd, development of zinc molybdate from enriched 100Mo, highly radiopure zinc tungstate for double beta and dark matter experiments, production of bismuth germinate for frontier experiments in high energy physics.

Grigoriev, D. N.; Danevich, F. A.; Shlegel, V. N.; Vasiliev, Ya V.

2014-09-01

424

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

425

Multi-response analysis in the material characterisation of electrospun poly (lactic acid)/halloysite nanotube composite fibres based on Taguchi design of experiments: fibre diameter, non-intercalation and nucleation effects  

NASA Astrophysics Data System (ADS)

Poly (lactic acid) (PLA)/halloysite nanotube (HNT) composite fibres were prepared by using a simple and versatile electrospinning technique. The systematic approach via Taguchi design of experiments (DoE) was implemented to investigate factorial effects of applied voltage, feed rate of solution, collector distance and HNT concentration on the fibre diameter, HNT non-intercalation and nucleation effects. The HNT intercalation level, composite fibre morphology, their associated fibre diameter and thermal properties were evaluated by means of X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), imaging analysis and differential scanning calorimetry (DSC), respectively. HNT non-intercalation phenomenon appears to be manifested as reflected by the minimal shift of XRD peaks for all electrospun PLA/HNT composite fibres. The smaller-fibre-diameter characteristic was found to be sequentially associated with the feed rate of solution, collector distance and applied voltage. The glass transition temperature ( T g) and melting temperature ( T m) are not highly affected by varying the material and electrospinning parameters. However, as the indicator of the nucleation effect, the crystallisation temperature ( T c) of PLA/HNT composite fibres is predominantly impacted by HNT concentration and applied voltage. It is evident that HNT's nucleating agent role is confirmed when embedded with HNTs to accelerate the cold crystallisation of composite fibres. Taguchi DoE method has been found to be an effective approach to statistically optimise critical parameters used in electrospinning in order to effectively tailor the resulting physical features and thermal properties of PLA/HNT composite fibres.

Dong, Yu; Bickford, Thomas; Haroosh, Hazim J.; Lau, Kin-Tak; Takagi, Hitoshi

2013-09-01

426

Cold-cap reactions in vitrification of nuclear waste glass: experiments and modeling  

SciTech Connect

Cold-cap reactions are multiple overlapping reactions that occur in the waste-glass melter during the vitrification process when the melter feed is being converted to molten glass. In this study, we used differential scanning calorimetry (DSC) to investigate cold-cap reactions in a high-alumina high-level waste melter feed. To separate the reaction heat from both sensible heat and experimental instability, we employed the run/rerun method, which enabled us to define the degree of conversion based on the reaction heat and to estimate the heat capacity of the reacting feed. Assuming that the reactions are nearly independent and can be approximated by the nth order kinetics, we obtained the kinetic parameters using the Kissinger method combined with least squares analysis. The resulting mathematical simulation of the cold-cap reactions provides a key element for the development of an advanced cold-cap model.

Chun, Jaehun [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Pierce, David A. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Pokorny, Richard [Inst. of Chemical Technology, Prague (Czech Republic); Hrma, Pavel R. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Pohang Univ. of Science and Techology (Korea, Republic of)

2013-05-10

427

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

PubMed

We demonstrate application of precise adiabatic vacuum calorimetry to observation of phase transition in the tripeptide L-alanyl-L-prolyl-glycine monohydrate (APG) from 6 to 320 K and report the standard thermodynamic properties of the tripeptide in the entire range. Thus, the heat capacity of APG was measured by adiabatic vacuum calorimetry in the above temperature range. The tripeptide exhibits a reversible first-order solid-to-solid phase transition characterized by strong thermal hysteresis. We report the standard thermodynamic characteristics of this transition and show that differential scanning calorimetry can reliably characterize the observed phase transition with <5 mg of the sample. Additionally, the standard entropy of formation from the elemental substances and the standard entropy of hypothetical reaction of synthesis from the amino acids at 298.15 K were calculated for the studied tripeptide. PMID:25588051

Markin, Alexey V; Markhasin, Evgeny; Sologubov, Semen S; Ni, Qing Zhe; Smirnova, Natalia N; Griffin, Robert G

2015-02-01

428

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

SciTech Connect

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

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

1988-01-01

429

Glass softening, crystallization, and vaporization of nano-aggregates of Amorphous Solid Water: Fast Scanning Calorimetry studies  

E-print Network

Fast scanning calorimetry (FSC) was employed to investigate glass softening dynamics in amorphous solid water (ASW) nano-aggregates with thicknesses ranging from 2 to 20 nm. ASW nano-aggregates were prepared by vapor-deposition on the surface of a tungsten filament near 141 K and then heated at a rate of 100 kK/s. The resulting thermogram complex endo- and exothermal features were analyzed using a simple model. The results of the analysis show that glass softening of ASW nano-aggregates takes place at 160 K and vaporization of ASW nano-aggregates can take place at temperatures as low as 185 K. The results of these studies are discussed in conjunction with results of past studies of glass softening dynamics in water in various confining geometries.

Deepanjan Bhattacharya; Liam OReilly; Vlad Sadtchenko

2014-10-31

430

Flow calorimetry--a useful tool for determination of immobilized cis-epoxysuccinate hydrolase activity from Nocardia tartaricans.  

PubMed

Bacterial cells Nocardia tartaricans with cis-epoxysuccinate hydrolase activity were entrapped in hardened calcium pectate gel by a commercial high performance encapsulator. This enzyme (in a single step reaction with no formation of side products) was used to hydrolyze disodium cis-epoxysuccinate to a pure enantiomer--disodium L-(+)-tartrate. Activities of this enzyme were determined using flow calorimetry. The validity of this method was corroborated by HPLC and isotachophoresis. The immobilized biocatalyst has activity (75.8 U/mgdry) able to convert disodium cis-epoxysuccinate to disodium tartrate at 94% yield in 5.5h. Immobilization of N. tartaricans in hardened calcium pectate gel beads had a positive effect on the activity of cis-epoxysuccinate hydrolase, storage stability, yield, and time of bioconversion. PMID:15027803

Vikartovská, Alica; Bucko, Marek; Gemeiner, Peter; Nahálka, Jozef; Pätoprstý, Vladimir; Hrabárová, Eva

2004-02-01

431

Probing volumetric properties of biomolecular systems by pressure perturbation calorimetry (PPC) - The effects of hydration, cosolvents and crowding.  

PubMed

Pressure perturbation calorimetry (PPC) is an efficient technique to study the volumetric properties of biomolecules in solution. In PPC, the coefficient of thermal expansion of the partial volume of the biomolecule is deduced from the heat consumed or produced after small isothermal pressure-jumps. The expansion coefficient strongly depends on the interaction of the biomolecule with the solvent or cosolvent as well as on its packing and internal dynamic properties. This technique, complemented with molecular acoustics and densimetry, provides valuable insights into the basic thermodynamic properties of solvation and volume effects accompanying interactions, reactions and phase transitions of biomolecular systems. After outlining the principles of the technique, we present representative examples on protein folding, including effects of cosolvents and crowding, together with a discussion of the interpretation, and further applications. PMID:25168090

Suladze, Saba; Kahse, Marie; Erwin, Nelli; Tomazic, Daniel; Winter, Roland

2015-04-01

432

Stiffness transitions in SixSe1-x glasses from Raman scattering and temperature-modulated differential scanning calorimetry  

NASA Astrophysics Data System (ADS)

Temperature-modulated differential scanning calorimetry (MDSC) measurements on SixSe1-x glasses show glass transitions to be thermally reversing in character in the composition window 0.200.27, the CS mode in addition to the ES and CM also splits into a doublet indicating growth of substantial medium range structure. The large compositional width (0.20

Selvanathan, D.; Bresser, W. J.; Boolchand, P.

2000-06-01

433

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

PubMed

Bixin is the major coloring component of annatto used in manufacturing colored cheeses, but its presence in liquid whey causes undesirable quality of the recovered whey protein ingredients. The objective of this work was to study molecular binding between bixin and three major whey proteins (?-lactoglobulin, ?-lactalbumin, and bovine serum albumin) at pH 7.4 using UV-vis absorption spectroscopy, fluorescence spectroscopy, isothermal titration calorimetry, and circular dichroism. These complementary techniques illustrated that the binding is a spontaneous complexation process mainly driven by hydrophobic interactions. The complexation is favored at a lower temperature and a higher ionic strength. At a lower temperature, the binding is entropy-driven, while it changes to an enthalpy-driven process at higher temperatures. The binding also increases the percentage of unordered secondary structures of proteins. Findings from this work can be used to develop whey protein recovery processes for minimizing residual annatto content in whey protein ingredients. PMID:22268806

Zhang, Yue; Zhong, Qixin

2012-02-22

434

Measuring thermal diffusivity of mechanical and optical grades of polycrystalline diamond using an AC laser calorimetry method  

SciTech Connect

Because of its extremely high thermal conductivity, measuring the thermal conductivity or diffusivity of optical-grade diamond can be challenging. Various methods have been used to measure the thermal conductivity of thick diamond films. For the purposes of commercial quality control, the AC laser calorimetry method is appealing because it enables fairly rapid and convenient sample preparation and measurement. In this paper, the method is used to measure the thermal diffusivity of optical diamond. It is found that sample dimensions and measurement parameters are critical, and data analysis must be performed with great care. The results suggest that the method as it is applied to optical-grade diamond could be enhanced by a more powerful laser, higher frequency beam modulation, and post-processing based on 2D thermal simulation.

Rule, Toby D. [II-VI Incorporated; Cai, Wei [ORNL; Wang, Hsin [ORNL

2013-01-01

435

Development of a water calorimetry-based standard for absorbed dose to water in HDR {sup 192}Ir brachytherapy  

SciTech Connect

Purpose: The aim of this article is to develop and evaluate a primary standard for HDR {sup 192}Ir brachytherapy based on 4 deg. C stagnant water calorimetry. Methods: The absolute absorbed dose to water was directly measured for several different Nucletron microSelectron {sup 192}Ir sources of air kerma strength ranging between 21 000 and 38 000 U and for source-to-detector separations ranging between 25 and 70 mm. The COMSOL MULTIPHYSICS software was used to accurately calculate the heat transport in a detailed model geometry. Through a coupling of the ''conduction and convection'' module with the ''Navier-Stokes incompressible fluid'' module in the software, both the conductive and convective effects were modeled. Results: A detailed uncertainty analysis resulted in an overall uncertainty in the absorbed dose of 1.90%(1{sigma}). However, this includes a 1.5% uncertainty associated with a nonlinear predrift correction which can be substantially reduced if sufficient time is provided for the system to come to a new equilibrium in between successive calorimetric runs, an opportunity not available to the authors in their clinical setting due to time constraints on the machine. An average normalized dose rate of 361{+-}7 {mu}Gy/(h U) at a source-to-detector separation of 55 mm was measured for the microSelectron {sup 192}Ir source based on water calorimetry. The measured absorbed dose per air kerma strength agreed to better than 0.8%(1{sigma}) with independent ionization chamber and EBT-1 Gafchromic film reference dosimetry as well as with the currently accepted AAPM TG-43 protocol measurements. Conclusions: This work paves the way toward a primary absorbed dose to water standard in {sup 192}Ir brachytherapy.

Sarfehnia, Arman; Seuntjens, Jan [Medical Physics Unit, McGill University, Montreal General Hospital, Montreal, Quebec H3G 1A4 (Canada)

2010-04-15

436

Particle Size (Sieving) and Enthalpy (Acid Calorimetry) Analysis of Single-Pull K East Basin Floor and Pit Sludges  

SciTech Connect

This report presents the results of particle size analyses and calorimetry testing performed on selected single-pull sludge samples collected from the Hanford K East Basin between December 1998 and June 1999. The samples were collected as isolated cores predominantly from areas that had not been previously sampled (e.g., North Loadout Pit, Dummy Elevator Pit, Tech View Pit), or from areas in which the sludge composition had been altered since the last sampling (e.g., Weasel Pit). Particle size analyses were performed by washing wet sludge samples through a series of four sieves with openings of 250, 500, 1410, and 4000 {micro}m. The loaded sieves were weighed before and after drying to obtain wet and dry particle size distributions. Knowledge of the particle size distribution is needed to design and predict the performance of the systems that will be used to retrieve, transport, and recover sludge. Also, sieving provides an opportunity to observe the components in the sludge. For example, during sieving of the sludge sample from the North Loadout Pit, significant quantities of organic ion exchange beads were observed. The uranium metal content and the particle size of the uranium metal in the K Basin sludge will largely determine the chemical reactivity of the sludge. In turn, the designs for the sludge handling and storage systems must be compatible with the reactivity of the sludge. Therefore, acid calorimetry was performed to estimate the uranium metal content of the sludge. For this testing, sludge samples were dissolved in nitric acid within a calibrated adiabatic calorimeter. The resulting dissolution enthalpy data were then used to discriminate between metallic uranium ({minus}3750 J/g in nitric acid) and uranium oxide ({minus}394 J/g in nitric acid). Results from this testing showed that the single-pull sludge samples contained little or no uranium metal.

PR Bredt; CH Delegard; AJ Schmidt; KL Silvers; BM Thornton; S Gano

2000-12-22

437

Synthesis of a Self-Healing Polymer Based on Reversible Diels-Alder Reaction: An Advanced Undergraduate Laboratory at the Interface of Organic Chemistry and Materials Science  

ERIC Educational Resources Information Center

This laboratory experiment exposes students to the chemistry of self-healing polymers based on a Diels-Alder reaction. Students accomplish a multistep synthesis of a monomer building block and then polymerize it to form a cross-linked polymer. The healing capability of the polymer is verified by differential scanning calorimetry (DSC) experiments.…

Weizman, Haim; Nielsen, Christian; Weizman, Or S.; Nemat-Nasser, Sia

2011-01-01

438

Piezoelectric resonance calorimetry of nonlinear-optical crystals under laser irradiation  

NASA Astrophysics Data System (ADS)

Novel method is proposed for determination of nonlinear-optical crystal both heat transfer and optical absorption coefficients by measuring kinetics of the laser-irradiated crystal temperature-dependent piezoelectric resonance frequency. When laser radiation propagates through the crystal its temperature evaluation with time is directly determined from crystal piezoelectric resonance frequency shift, which is precisely measured by analyzing crystal response to the applied ac electric voltage. Heat transfer and optical absorption coefficients are obtained using measured characteristic time of crystal laser heating kinetics by solving nonstationary heat conduction equation. Experiments were performed with nonlinear-optical ?-quartz, lithium triborate (LBO) and periodically poled lithium niobate (PPLN) crystals.

Ryabushkin, Oleg A.; Konyashkin, Aleksey V.; Myasnikov, Daniil V.; Tyrtyshnyy, Valentin A.; Vershinin, Oleg I.

2013-09-01

439

Characterization of Rabbit Ear Skin as a Skin Model for in vitro Transdermal Permeation Experiments: Histology, Lipid Composition and Permeability  

Microsoft Academic Search

Aim: The aim of this work was to characterize rabbit ear skin in view of its use in transdermal permeation experiments. Method: The characterization included histological analysis of the tissue, qualitative and quantitative analysis of stratum corneum (SC) lipids, differential scanning calorimetry and permeation experiments (caffeine, nicotinamide, progesterone). As a reference, pig ear skin was used. Results: The results obtained

S. Nicoli; C. Padula; V. Aversa; B. Vietti; P. W. Wertz; A. Millet; F. Falson; P. Govoni; P. Santi

2008-01-01

440

5/29/09 6:33 PMGlobal Warming and Cyclones: a Vicious Cycle? : Discovery News Page 1 of 3http://dsc.discovery.com/news/2009/05/14/tropical-cyclones-warming-print.html  

E-print Network

://dsc.discovery.com/news/2009/05/14/tropical-cyclones-warming-print.html Discovery Channel « back Global Warming and Tropical Cyclones: a Vicious Cycle? Emily Sohn, Discovery News May 14, 2009 -- Global warming can change storm patterns. In turn, storms might help fuel global warming. A new study suggests that tropical cyclones shoot

Romps, David M.

441

Thermal conductivity measurements for small molecule organic solid materials using modulated differential scanning calorimetry (MDSC) and data corrections for sample porosity  

Microsoft Academic Search

A method for measuring the thermal conductivity (k) of small molecule organic solid materials using modulated differential scanning calorimetry (MDSC) is demonstrated. Sample preparation required powder consolidation, unavoidably introducing air voids into compacts. Supporting equations for the technique were modified to include a porosity term (?), and the theoretical quadratic relationship between k and ? was confirmed by experimental measurements

Yannan Lin; Zhenqi Shi; Peter L. D. Wildfong

2010-01-01

442

Characterization of the molecular distribution of drugs in glassy solid dispersions at the nano-meter scale, using differential scanning calorimetry and gravimetric water vapour sorption techniques.  

PubMed

The molecular distribution in fully amorphous solid dispersions consisting of poly(vinylpyrrolidone) (PVP)-diazepam and inulin-diazepam was studied. One glass transition temperature (T(g)), as determined by temperature modulated differential scanning calorimetry (TMDSC), was observed in PVP-diazepam solid dispersions prepared by fusion for all drug loads tested (10-80 wt.%). The T(g) of these solid dispersions gradually changed with composition and decreased from 177 degrees C for pure PVP to 46 degrees C for diazepam. These observations indicate that diazepam was dispersed in PVP on a molecular level. However, in PVP-diazepam solid dispersions prepared by freeze drying, two T(g)'s were observed for drug loads above 35 wt.% indicating phase separation. One T(g) indicated the presence of amorphous diazepam clusters, the other T(g) was attributed to a PVP-rich phase in which diazepam was dispersed on a molecular level. With both the value of the latter T(g) and the DeltaC(p) of the diazepam glass transition the concentrations of molecular dispersed diazepam could be calculated (27-35 wt.%). Both methods gave similar results. Water vapour sorption (DVS) experiments revealed that the PVP-matrix was hydrophobised by the incorporated diazepam. TMDSC and DVS results were used to estimate the size of diazepam clusters in freeze dried PVP-diazepam solid dispersions, which appeared to be in the nano-meter range. The inulin-diazepam solid dispersions prepared by spray freeze drying showed one T(g) for drug loads up to 35 wt.% indicating homogeneous distribution on a molecular level. However, this T(g) was independent of the drug load, which is unexpected because diazepam has a lower T(g) than inulin (46 and 155 degrees C, respectively). For higher drug loads, a T(g) of diazepam as well as a T(g) of the inulin-rich phase was observed, indicating the formation of amorphous diazepam clusters. From the DeltaC(p) of the diazepam glass transition the amount of molecularly dispersed diazepam was calculated (12-27 wt.%). In contrast to the PVP-diazepam solid dispersions, DVS-experiments revealed that inulin was not hydrophobised by diazepam. Consequently, the size of diazepam clusters could not be estimated. It was concluded that TMDSC enables characterization and quantification of the molecular distribution in amorphous solid dispersions. When the hygroscopicity of the carrier is reduced by the drug, DVS in combination with TMDSC can be used to estimate the size of amorphous drug clusters. PMID:16427226

van Drooge, D J; Hinrichs, W L J; Visser, M R; Frijlink, H W

2006-03-01

443

Nuclear Calorimetry on GeV Proton Induced Target Multifragmentation Reactions  

NASA Astrophysics Data System (ADS)

A series of GeV proton induced target multifragmentation experiments have been performed at KEK-PS (12/8GeV p + Au, Tm, Sm, Ag).Intermediate mass fragments (IMFs; 3<= Z <= 25) have been detected with a 37-channel Bragg-Curve Counter array. Kinetic energy and charge have been determined for all the detected IMFs. In addition, mass separation for Li and Be fragments has been performed. Emission angle, target mass and IMF-multiplicity dependences have been studied for the energy spectra. All the energy spectra have been well described with ``deformed moving source model''. The fragment emission-angle dependence of the nuclear temperature and free nucleon density has been measured for the first time using yield ratios of the lithium and beryllium isotopes. ``U-Shaped'' angular distributions have been observed for both of the temperature and free nucleon density. This fact suggests that the temperature and density distributions in the emission source of IMFs should not be uniform. The existence of non-uniformity could be the origin of the sideward-yield enhancement of the IMF production.

Murata, Jiro

1999-10-01

444

Initial results of a silicon sensor irradiation study for ILC extreme forward calorimetry  

NASA Astrophysics Data System (ADS)

Detectors proposed for the International Linear Collider (ILC) incorporate a tungsten sampling calorimeter ('BeamCal') intended to reconstruct showers of electrons, positrons and photons that emerge from the interaction point of the collider with angles between 5 and 50 milliradians. For the innermost radius of this calorimeter, radiation doses at shower-max are expected to reach 100 MRad per year, primarily due to minimum-ionizing electrons and positrons that arise in the induced electromagnetic showers of e+e- 'beamstrahlung' pairs produced in the ILC beam-beam interaction. However, radiation damage to calorimeter sensors may be dominated by hadrons induced by nuclear interactions of shower photons, which are much more likely to contribute to the non-ionizing energy loss that has been observed to damage sensors exposed to hadronic radiation. We report here on t