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Sample records for models whole-animal calorimetry

  1. High Throughput Screen for Novel Antimicrobials using a Whole Animal Infection Model

    OpenAIRE

    Moy, Terence I.; Annie L Conery; Larkins-Ford, Jonah; Wu, Gang; Mazitschek, Ralph; Casadei, Gabriele; Lewis, Kim; Carpenter, Anne E.; Ausubel, Frederick M.

    2009-01-01

    The nematode Caenorhabditis elegans is a unique whole animal model system for identifying small molecules with in vivo anti-infective properties. C. elegans can be infected with a broad range of human pathogens, including Enterococcus faecalis, an important human nosocomial pathogen with a mortality rate of up to 37% that is increasingly acquiring resistance to antibiotics. Here, we describe an automated, high throughput screen of 37,200 compounds and natural product extracts for those that e...

  2. Photodynamic and antibiotic therapy impair the pathogenesis of Enterococcus faecium in a whole animal insect model.

    Directory of Open Access Journals (Sweden)

    José Chibebe Junior

    Full Text Available Enterococcus faecium has emerged as one of the most important pathogens in healthcare-associated infections worldwide due to its intrinsic and acquired resistance to many antibiotics, including vancomycin. Antimicrobial photodynamic therapy (aPDT is an alternative therapeutic platform that is currently under investigation for the control and treatment of infections. PDT is based on the use of photoactive dye molecules, widely known as photosensitizer (PS. PS, upon irradiation with visible light, produces reactive oxygen species that can destroy lipids and proteins causing cell death. We employed Galleria mellonella (the greater wax moth caterpillar fatally infected with E. faecium to develop an invertebrate host model system that can be used to study the antimicrobial PDT (alone or combined with antibiotics. In the establishment of infection by E. faecium in G. mellonella, we found that the G. mellonella death rate was dependent on the number of bacterial cells injected into the insect hemocoel and all E. faecium strains tested were capable of infecting and killing G. mellonella. Antibiotic treatment with ampicillin, gentamicin or the combination of ampicillin and gentamicin prolonged caterpillar survival infected by E. faecium (P = 0.0003, P = 0.0001 and P = 0.0001, respectively. In the study of antimicrobial PDT, we verified that methylene blue (MB injected into the insect followed by whole body illumination prolonged the caterpillar survival (P = 0.0192. Interestingly, combination therapy of larvae infected with vancomycin-resistant E. faecium, with antimicrobial PDT followed by vancomycin, significantly prolonged the survival of the caterpillars when compared to either antimicrobial PDT (P = 0.0095 or vancomycin treatment alone (P = 0.0025, suggesting that the aPDT made the vancomycin resistant E. faecium strain more susceptible to vancomycin action. In summary, G. mellonella provides an invertebrate model host to

  3. Computational and bioengineered lungs as alternatives to whole animal, isolated organ, and cell-based lung models.

    Science.gov (United States)

    Patel, Brijeshkumar; Gauvin, Robert; Absar, Shahriar; Gupta, Vivek; Gupta, Nilesh; Nahar, Kamrun; Khademhosseini, Ali; Ahsan, Fakhrul

    2012-11-01

    Development of lung models for testing a drug substance or delivery system has been an intensive area of research. However, a model that mimics physiological and anatomical features of human lungs is yet to be established. Although in vitro lung models, developed and fine-tuned over the past few decades, were instrumental for the development of many commercially available drugs, they are suboptimal in reproducing the physiological microenvironment and complex anatomy of human lungs. Similarly, intersubject variability and high costs have been major limitations of using animals in the development and discovery of drugs used in the treatment of respiratory disorders. To address the complexity and limitations associated with in vivo and in vitro models, attempts have been made to develop in silico and tissue-engineered lung models that allow incorporation of various mechanical and biological factors that are otherwise difficult to reproduce in conventional cell or organ-based systems. The in silico models utilize the information obtained from in vitro and in vivo models and apply computational algorithms to incorporate multiple physiological parameters that can affect drug deposition, distribution, and disposition upon administration via the lungs. Bioengineered lungs, on the other hand, exhibit significant promise due to recent advances in stem or progenitor cell technologies. However, bioengineered approaches have met with limited success in terms of development of various components of the human respiratory system. In this review, we summarize the approaches used and advancements made toward the development of in silico and tissue-engineered lung models and discuss potential challenges associated with the development and efficacy of these models.

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

    Science.gov (United States)

    Herrera, Isaac; Winnik, Mitchell A

    2016-03-10

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

  5. The ketogenic diet metabolite beta-hydroxybutyrate (β-HB) reduces incidence of seizure-like activity (SLA) in a Katp- and GABAb-dependent manner in a whole-animal Drosophila melanogaster model.

    Science.gov (United States)

    Li, Jinglu; O'Leary, Emma I; Tanner, Geoffrey R

    2017-07-01

    The high-fat, low-carbohydrate ketogenic diet (KD) is an effective clinical treatment for epilepsy in juveniles, especially for drug-resistant seizures. The KD results in elevated production of ketone bodies (KB's), such as beta-hydroxybutyrate (β-HB), which are thought to have anticonvulsant properties; however, their exact mechanism of action is unknown. In vitro, KB effects on reducing neuronal firing rates are mediated in part by Katp channel activity and GABAb signaling. In order to study metabolic and pharmacological effects in a whole-animal model, we used the eas "bang-sensitive" (BS) mutant strain of Drosophila, which exhibits seizure-like activity (SLA) upon mechanical stimulation. Direct application of the KB β-HB to food reduced BS SLA. Application either of tolbutamide, a Katp blocker, or of CGP-55845, a GABAb antagonist, concomitantly with β-HB, partially reversed these KB effects on SLA, verifying a role for Katp channels and GABAb signaling in mediating the anticonvulsant effects of KB's and validating this whole-animal model of KD effects on seizure. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Multiscale Modeling of Antibody-Drug Conjugates: Connecting Tissue and Cellular Distribution to Whole Animal Pharmacokinetics and Potential Implications for Efficacy.

    Science.gov (United States)

    Cilliers, Cornelius; Guo, Hans; Liao, Jianshan; Christodolu, Nikolas; Thurber, Greg M

    2016-09-01

    Antibody-drug conjugates exhibit complex pharmacokinetics due to their combination of macromolecular and small molecule properties. These issues range from systemic concerns, such as deconjugation of the small molecule drug during the long antibody circulation time or rapid clearance from nonspecific interactions, to local tumor tissue heterogeneity, cell bystander effects, and endosomal escape. Mathematical models can be used to study the impact of these processes on overall distribution in an efficient manner, and several types of models have been used to analyze varying aspects of antibody distribution including physiologically based pharmacokinetic (PBPK) models and tissue-level simulations. However, these processes are quantitative in nature and cannot be handled qualitatively in isolation. For example, free antibody from deconjugation of the small molecule will impact the distribution of conjugated antibodies within the tumor. To incorporate these effects into a unified framework, we have coupled the systemic and organ-level distribution of a PBPK model with the tissue-level detail of a distributed parameter tumor model. We used this mathematical model to analyze new experimental results on the distribution of the clinical antibody-drug conjugate Kadcyla in HER2-positive mouse xenografts. This model is able to capture the impact of the drug-antibody ratio (DAR) on tumor penetration, the net result of drug deconjugation, and the effect of using unconjugated antibody to drive ADC penetration deeper into the tumor tissue. This modeling approach will provide quantitative and mechanistic support to experimental studies trying to parse the impact of multiple mechanisms of action for these complex drugs.

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

    Science.gov (United States)

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

    2012-12-21

    A mathematical model based on conservation of energy has been developed and used to simulate the temperature responses of cones of the Australian cycads Macrozamia lucida and Macrozamia. macleayi during their daily thermogenic cycle. These cones generate diel midday thermogenic temperature increases as large as 12 °C above ambient during their approximately two week pollination period. The cone temperature response model is shown to accurately predict the cones' temperatures over multiple days as based on simulations of experimental results from 28 thermogenic events from 3 different cones, each simulated for either 9 or 10 sequential days. The verified model is then used as the foundation of a new, parameter estimation based technique (termed inverse calorimetry) that estimates the cones' daily metabolic heating rates from temperature measurements alone. The inverse calorimetry technique's predictions of the major features of the cones' thermogenic metabolism compare favorably with the estimates from conventional respirometry (indirect calorimetry). Because the new technique uses only temperature measurements, and does not require measurements of oxygen consumption, it provides a simple, inexpensive and portable complement to conventional respirometry for estimating metabolic heating rates. It thus provides an additional tool to facilitate field and laboratory investigations of the bio-physics of thermogenic plants. Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. Measurement and Model Validation of Nanofluid Specific Heat Capacity with Differential Scanning Calorimetry

    Directory of Open Access Journals (Sweden)

    Harry O'Hanley

    2012-01-01

    Full Text Available Nanofluids are being considered for heat transfer applications; therefore it is important to know their thermophysical properties accurately. In this paper we focused on nanofluid specific heat capacity. Currently, there exist two models to predict a nanofluid specific heat capacity as a function of nanoparticle concentration and material. Model I is a straight volume-weighted average; Model II is based on the assumption of thermal equilibrium between the particles and the surrounding fluid. These two models give significantly different predictions for a given system. Using differential scanning calorimetry (DSC, a robust experimental methodology for measuring the heat capacity of fluids, the specific heat capacities of water-based silica, alumina, and copper oxide nanofluids were measured. Nanoparticle concentrations were varied between 5 wt% and 50 wt%. Test results were found to be in excellent agreement with Model II, while the predictions of Model I deviated very significantly from the data. Therefore, Model II is recommended for nanofluids.

  9. Whole-animal imaging with high spatio-temporal resolution

    Science.gov (United States)

    Chhetri, Raghav; Amat, Fernando; Wan, Yinan; Höckendorf, Burkhard; Lemon, William C.; Keller, Philipp J.

    2016-03-01

    We developed isotropic multiview (IsoView) light-sheet microscopy in order to image fast cellular dynamics, such as cell movements in an entire developing embryo or neuronal activity throughput an entire brain or nervous system, with high resolution in all dimensions, high imaging speeds, good physical coverage and low photo-damage. To achieve high temporal resolution and high spatial resolution at the same time, IsoView microscopy rapidly images large specimens via simultaneous light-sheet illumination and fluorescence detection along four orthogonal directions. In a post-processing step, these four views are then combined by means of high-throughput multiview deconvolution to yield images with a system resolution of ≤ 450 nm in all three dimensions. Using IsoView microscopy, we performed whole-animal functional imaging of Drosophila embryos and larvae at a spatial resolution of 1.1-2.5 μm and at a temporal resolution of 2 Hz for up to 9 hours. We also performed whole-brain functional imaging in larval zebrafish and multicolor imaging of fast cellular dynamics across entire, gastrulating Drosophila embryos with isotropic, sub-cellular resolution. Compared with conventional (spatially anisotropic) light-sheet microscopy, IsoView microscopy improves spatial resolution at least sevenfold and decreases resolution anisotropy at least threefold. Compared with existing high-resolution light-sheet techniques, such as lattice lightsheet microscopy or diSPIM, IsoView microscopy effectively doubles the penetration depth and provides subsecond temporal resolution for specimens 400-fold larger than could previously be imaged.

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

    Science.gov (United States)

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

    2013-03-01

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

  11. Automated whole animal bio-imaging assay for human cancer dissemination.

    Directory of Open Access Journals (Sweden)

    Veerander P S Ghotra

    Full Text Available A quantitative bio-imaging platform is developed for analysis of human cancer dissemination in a short-term vertebrate xenotransplantation assay. Six days after implantation of cancer cells in zebrafish embryos, automated imaging in 96 well plates coupled to image analysis algorithms quantifies spreading throughout the host. Findings in this model correlate with behavior in long-term rodent xenograft models for panels of poorly- versus highly malignant cell lines derived from breast, colorectal, and prostate cancer. In addition, cancer cells with scattered mesenchymal characteristics show higher dissemination capacity than cell types with epithelial appearance. Moreover, RNA interference establishes the metastasis-suppressor role for E-cadherin in this model. This automated quantitative whole animal bio-imaging assay can serve as a first-line in vivo screening step in the anti-cancer drug target discovery pipeline.

  12. Indirect calorimetry

    NARCIS (Netherlands)

    Gerrits, W.J.J.; Labussière, E.

    2015-01-01

    The use of indirect calorimetry to measure the heat production of men and animals has increased rapidly since the pioneering work of Lavoisier. Measurement of the consumption of oxygen and production of carbon dioxide are the basis for the measurement of heat production. Today, applications of indir

  13. Application of TZERO calibrated modulated temperature differential scanning calorimetry to characterize model protein formulations.

    Science.gov (United States)

    Badkar, Aniket; Yohannes, Paulos; Banga, Ajay

    2006-02-17

    The objective of this study was to evaluate the feasibility of using T(ZERO) modulated temperature differential scanning calorimetry (MDSC) as a novel technique to characterize protein solutions using lysozyme as a model protein and IgG as a model monoclonal antibody. MDSC involves the application of modulated heating program, along with the standard heating program that enables the separation of overlapping thermal transitions. Although characterization of unfolding transitions for protein solutions requires the application of high sensitive DSC, separation of overlapping transitions like aggregation and other exothermic events may be possible only by use of MDSC. A newer T(ZERO) calibrated MDSC model from TA instruments that has improved sensitivity than previous models was used. MDSC analysis showed total, reversing and non-reversing heat flow signals. Total heat flow signals showed a combination of melting endotherms and overlapping exothermic events. Under the operating conditions used, the melting endotherms were seen in reversing heat flow signal while the exothermic events were seen in non-reversing heat flow signal. This enabled the separation of overlapping thermal transitions, improved data analysis and decreased baseline noise. MDSC was used here for characterization of lysozyme solutions, but its feasibility for characterizing therapeutic protein solutions needs further assessment.

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

    Science.gov (United States)

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

    2013-08-01

    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.

  15. Isothermal calorimetry: a predictive tool to model drug-propellant interactions in pressurized metered dose systems.

    Science.gov (United States)

    Ooi, Jesslynn; Gaisford, Simon; Boyd, Ben J; Young, Paul M; Traini, Daniela

    2014-01-30

    The purpose of this work was to evaluate gas perfusion isothermal calorimetry (ITC) as a method to characterize the physicochemical changes of active pharmaceutical ingredients (APIs) intended to be formulated in pressurized metered dose inhalers (pMDIs) after exposure to a model propellant. Spray dried samples of beclomethasone dipropionate (BDP) and salbutamol sulphate (SS) were exposed to controlled quantities of 2H,3H-decafluoropentane (HPFP) to determine whether ITC could be used as a suitable analytical method for gathering data on the behavioural properties of the powders in real time. The crystallization kinetics of BDP and the physiochemical properties of SS were successfully characterized using ITC and supported by a variety of other analytical techniques. Correlations between real and model propellant systems were also established using hydrofluoroalkane (HFA-227) propellant. In summary, ITC was found to be suitable for gathering data on the crystallization kinetics of BDP and SS. In a wider context, this work will have implications on the use of ITC for stability testing of APIs in HFA-based pMDIs.

  16. Quantum Calorimetry

    Science.gov (United States)

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

    1999-01-01

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

  17. Quantum Calorimetry

    Science.gov (United States)

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

    1999-01-01

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

  18. Pressure Perturbation Calorimetry of Apolipoproteins in Solution and in Model Lipoproteins

    Science.gov (United States)

    Benjwal, Sangeeta; Gursky, Olga

    2009-01-01

    High-density lipoproteins (HDL) are complexes of lipids and proteins (termed apolipoproteins) that remove cell cholesterol and protect from atherosclerosis. Apolipoproteins contain amphipathic α-helices that have high content (≥1/3) and distinct distribution of charged and apolar residues, adopt molten globule-like conformations in solution, and bind to lipid surfaces. We report the first pressure perturbation calorimetry (PPC) study of apolipoproteins. In solution, the main HDL protein, apoA-I, shows relatively large volume contraction, ΔVunf=-0.33%, and an apparent reduction in thermal expansivity upon unfolding, Δαunf≤0, which has not been observed in other proteins. We propose that these values are dominated by increased charged residue hydration upon α-helical unfolding, which may result from disruption of multiple salt bridges. At 5°C, apoA-I shows large thermal expansion coefficient, α(5°) = 15·10-4 K-1, that rapidly declines upon heating from 5-40°C, α(40°)-α(5°)=-4·10-4 K-1; apolipoprotein C-I shows similar values of α(5°) and α(40°). These values are larger than in globular proteins. They indicate dominant effect of charged residue hydration, which may modulate functional apolipoprotein interactions with a broad range of their protein and lipid ligands. The first PPC analysis of a protein-lipid complex is reported, which focuses on the chain melting transition in model HDL containing apoA-I or apoC-I, dimyristoyl phosphatidylcholine, and 0–20% cholesterol. The results may provide new insights into volumetric properties of HDL that modulate metabolic lipoprotein remodeling during cholesterol transport. PMID:19927327

  19. Near infrared probes for biochemical, cellular, and whole animal analysis of disease processes

    Science.gov (United States)

    Kovar, Joy; Boveia, Vince; Chen, Huaxian; Peng, Xinzhan; Skopp, Rose; Little, Garrick; Draney, Dan; Olive, D. M.

    2009-02-01

    The study of disease processes requires a number of tools for detection of proteins and biomarkers in cell and animal based assays. Near infrared (NIR) technologies offer the advantage of high signal without interference from background producing factors such as tissues, blood, or plastics. NIR fluorescence quenching biochemical assays employing a novel NIR quencher are homogeneous and sensitive. NIR-based immunocytochemical assays offer a means of quantitatively evaluating cell signaling pathways. The technology can be extended to the development of targeted molecular imaging agents for disease analysis in animal models. We describe here model assays for each of these categories. A fluorescence quenching caspase-3 assay was developed employing a novel, broadly applicable quencher dye suitable for use with both visible and NIR dye chemistries. An NIR cell based assay is described for assessment of phosphorylation of p53 in response to a cellular stimulus. Finally, we describe the development and application of a targeted NIR optical imaging agent for monitoring tumor growth in whole animals. The NIR biochemical and cell based assays are robust with Z' factors greater than 0.7. The use of an IRDye (R)800CW-labeled cyclic RGD peptide is presented as a model for development and application of targeted imaging agents. NIR technologies are compatible with the complete spectrum of assay needs for disease analysis and therapeutic development.

  20. Evaluation of the interaction of coumarins with biomembrane models studied by differential scanning calorimetry and Langmuir-Blodgett techniques.

    Science.gov (United States)

    Sarpietro, Maria Grazia; Giuffrida, Maria Chiara; Ottimo, Sara; Micieli, Dorotea; Castelli, Francesco

    2011-04-25

    Three coumarins, scopoletin (1), esculetin (2), and esculin (3), were investigated by differential scanning calorimetry and Langmuir-Blodgett techniques to gain information about the interaction of these compounds with cellular membranes. Phospholipids assembled as multilamellar vesicles or monolayers (at the air-water interface) were used as biomembrane models. Differential scanning calorimetry was employed to study the interaction of these coumarins with multilamellar vesicles and to evaluate their absorption by multilamellar vesicles. These experiments indicated that 1-3 interact in this manner to different extents. The Langmuir-Blodgett technique was used to study the effect of these coumarins on the organization of phospholipids assembled as a monolayer. The data obtained were in agreement with those obtained in the calorimetric experiments.

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

    Science.gov (United States)

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

    2014-05-01

    The interaction between an amphiphilic luteinizing hormone-releasing hormone (LHRH) prodrug that incorporated a lipoamino acid moiety (C12-LAA) with biological membrane models that consisted of multilamellar liposomes (MLVs) and phospholipid monolayers, was studied using Differential Scanning Calorimetry (DSC) and Langmuir-Blodgett film techniques. The effect of the prodrug C12[Q1]LHRH on the lipid layers was compared with the results obtained with the pure precursors, LHRH and C12-LAA. Conjugation of LHRH with a LAA promoiety showed to improve the peptide interaction with biomembrane models. Basing on the calorimetric findings, the LAA moiety aided the transfer of the prodrug from an aqueous solution to the biomembrane model. Copyright © 2014 Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

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

    2009-04-08

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

  3. Differential scanning calorimetry approach to investigate the transfer of the multitarget opioid analgesic LP1 to biomembrane model.

    Science.gov (United States)

    Accolla, Maria Lorena; Turnaturi, Rita; Sarpietro, Maria Grazia; Ronsisvalle, Simone; Castelli, Francesco; Pasquinucci, Lorella

    2014-04-22

    An emerging approach in pain management is the use of multitarget opioid ligands, owing an improved analgesic effect coupled to a reduced incidence of side effects. With a mu opioid receptor agonist/delta opioid receptor antagonist profile, the benzomorphan-based compound LP1 belongs to multitarget ligands class. Previous in vivo investigations showed that LP1 - subcutaneously administered as oxalate salt - was an antinociceptive agent as potent as morphine with a low tolerance-inducing capability. Because the renal toxicity of oxalate is known, an alternative approach allowing the administration of LP1 freebase could be more biocompatible. In this study the interaction of LP1 freebase and LP1 oxalate salt with multilamellar vesicles, as membrane model, was evaluated using differential scanning calorimetry technique. Despite the good membrane interaction showed by LP1 freebase, it was not capable to diffuse in the aqueous medium and to be uptaken by multilamellar vesicles. On the other hand, LP1 freebase possessed a good transfer profile by a liposomal carrier to a biomembrane model. Considering our findings and the need of safe formulations, studies for the development of a suitable carrier for a systemic administration of LP1 freebase are in progress. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  4. Liver mitochondrial and whole-animal level metabolic compensation in a catfish during seasonal acclimatization

    Institute of Scientific and Technical Information of China (English)

    Yulian YAN; Xiaojun XIE

    2011-01-01

    To examine whether metabolic compensation during seasonal acclimatization at the liver mitochondrial level is consistent with that at the whole-animal level, respiration rates of liver mitochondria and resting metabolic rates in winter- and summer- acclimatized southern catfish (Silurus meridionalis Chen) were measured. At 12.5, 17.5, 22.5, 27.5 and 32.5℃, the mean values of state 3 respiration rates were 12.21, 13.84, 18.96, 24.78 and 32.01 nmol O2 min-1 mg-1 mitochondrial protein in the winter group, and 8.56, 9.20, 17.32, 22.74 and 26.32 nmol O2min-1 mg-1 in the summer group, respectively. At the five assay temperatures the resting metabolic rates were 24.86, 42.68, 61.59, 84.10 and 125.65 mg O2 h-1 kg-1 body mass in the winter group,and 22.89, 40.59, 52.94, 75.13 and 109.35 mg O2 h-1 kg-1 in the summer group, respectively. Total mitochondrial respiration rates in the liver organ were estimated based on state 3 respiration rates, mitochondrial protein content and organ mass, and the mean values were 72.96, 71.87, 112.47, 167.35 and 183.27 nmol O2min-1 in the winter group, and were 47.89, 47.39, 105.67, 138.18 and 132.29 nmol O2 min-1 in the summer group, respectively. Metabolic compensation caused by seasonal acclimatization occurred at the liver mitochondrial level and compensation at the liver organ level was found to be more efficient because of an increase in metabolic capacity of mitochondria and a boost in organ mass. Metabolic compensation at the whole-animal level was not detected. During seasonal acclimatization, the effect of metabolic compensation at liver mitochondrial level is inconsistent with that at the whole-animal level in the southern catfish. This may be due to different degrees of regulation of metabolic mechanisms among various tissues and organs in an acclimatized organism [Current Zoology 57 (1): 109-115, 2011].

  5. Langmuir monolayers and Differential Scanning Calorimetry for the study of the interactions between camptothecin drugs and biomembrane models.

    Science.gov (United States)

    Casadó, Ana; Giuffrida, M Chiara; Sagristá, M Lluïsa; Castelli, Francesco; Pujol, Montserrat; Alsina, M Asunción; Mora, Margarita

    2016-02-01

    CPT-11 and SN-38 are camptothecins with strong antitumor activity. Nevertheless, their severe side effects and the chemical instability of their lactone ring have questioned the usual forms for its administration and have focused the current research on the development of new suitable pharmaceutical formulations. This work presents a biophysical study of the interfacial interactions of CPT-11 and SN-38 with membrane mimetic models by using monolayer techniques and Differential Scanning Calorimetry. The aim is to get new insights for the understanding of the bilayer mechanics after drug incorporation and to optimize the design of drug delivery systems based on the formation of stable bilayer structures. Moreover, from our knowledge, the molecular interactions between camptothecins and phospholipids have not been investigated in detail, despite their importance in the context of drug action. The results show that neither CPT-11 nor SN-38 disturbs the structure of the complex liposome bilayers, despite their different solubility, that CPT-11, positively charged in its piperidine group, interacts electrostatically with DOPS, making stable the incorporation of a high percentage of CPT-11 into liposomes and that SN-38 establishes weak repulsive interactions with lipid molecules that modify the compressibility of the bilayer without affecting significantly neither the lipid collapse pressure nor the miscibility pattern of drug-lipid mixed monolayers. The suitability of a binary and a ternary lipid mixture for encapsulating SN-38 and CPT-11, respectively, has been demonstrated. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Isothermal titration calorimetry and differential scanning calorimetry.

    Science.gov (United States)

    Holdgate, Geoff

    2009-01-01

    Isothermal titration [Holdgate (BioTechniques 31:164-184, 2001); Ward and Holdgate (Prog. Med. Chem. 38:309-376, 2001); O'Brien et al. (2001) Isothermal titration calorimetry of biomolecules. In: Harding, S. E. and Chowdhry, B. Z. (eds.), Protein-Ligand Interactions: Hydrodynamics and Calorimetry, A Practical Approach. Oxford University Press, Oxford, UK] and differential scanning calorimetry [Jelesarov and Bosshard (J. Mol. Recognit. 12:3-18, 1999); Privalov and Dragan (Biophys. Chem. 126:16-24, 2007); Cooper et al. (2001) Differential scanning microcalorimetry. In: Harding, S. E. and Chowdhry, B. Z. (eds.), Protein-Ligand Interactions: Hydrodynamics and Calorimetry, A Practical Approach. Oxford University Press, Oxford, UK] are valuable tools for characterising protein targets, and their interactions with ligands, during the drug discovery process. The parameters obtained from these techniques: triangle DeltaH, triangle DeltaG, triangle DeltaS, and triangle DeltaC (p), are properties of the entire system studied and may be composed of many contributions, including the binding reaction itself, conformational changes of the protein and/or ligand during complexation, changes in solvent organisation or other equilibria linked to the binding process. Dissecting and understanding these components, and how they contribute to binding interactions, is a critical step in the ability to design ligands that have high binding affinity for the target protein.

  7. Dynamic Calorimetry for Students

    Science.gov (United States)

    Kraftmakher, Yaakov

    2007-01-01

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

  8. Dynamic Calorimetry for Students

    Science.gov (United States)

    Kraftmakher, Yaakov

    2007-01-01

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

  9. Influence of natural thermal gradients on whole animal rates of protein synthesis in marine gammarid amphipods.

    Directory of Open Access Journals (Sweden)

    Samuel P S Rastrick

    Full Text Available Although temperature is known to have an important effect on protein synthesis rates and growth in aquatic ectotherms held in the laboratory, little is known about the effects of thermal gradients on natural populations in the field. To address this issue we determined whole-animal fractional rates of protein synthesis (ks in four dominant species of gammarid amphipods with different distributions along the coasts of Western Europe from arctic to temperate latitudes. Up to three populations of each species were collected in the summer and ks measured within 48 h. Summer ks values were relatively high in the temperate species, Gammarus locusta, from Portugal (48°N and Wales (53°N and were maintained across latitudes by the conservation of translational efficiency. In sharp contrast, summer ks remained remarkably low in the boreal/temperate species G. duebeni from Wales, Scotland (58°N and Tromsø (70°N, probably as a temporary energy saving strategy to ensure survival in rapidly fluctuating environments of the high intertidal. Values for ks increased in acclimated G. duebeni from Scotland and Tromsø showing a lack of compensation with latitude. In the subarctic/boreal species, G. oceanicus, summer ks remained unchanged in Scotland and Tromsø but fell significantly in Svalbard (79°N at 5°C, despite a slight increase in RNA content. At 79°N, mean ks was 4.5 times higher in the circumpolar species G. setosus than in G. oceanicus due to a doubling in RNA content. The relationship between whole-animal protein synthesis rates and natural thermal gradients is complex, varies between species and appears to be associated with local temperatures and their variability, as well as changes in other environmental factors.

  10. Determination of thermodynamic potentials and the aggregation number for micelles with the mass-action model by isothermal titration calorimetry

    DEFF Research Database (Denmark)

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

    2015-01-01

    The aggregation number (n), thermodynamic potentials (ΔG, ΔH, ΔS) and critical micelle concentration (CMC) for 6 natural bile salts were determined on the basis of both original and previously published isothermal titration calorimetry (ITC) data. Different procedures to estimate parameters...

  11. Whole-animal functional and developmental imaging with isotropic spatial resolution.

    Science.gov (United States)

    Chhetri, Raghav K; Amat, Fernando; Wan, Yinan; Höckendorf, Burkhard; Lemon, William C; Keller, Philipp J

    2015-12-01

    Imaging fast cellular dynamics across large specimens requires high resolution in all dimensions, high imaging speeds, good physical coverage and low photo-damage. To meet these requirements, we developed isotropic multiview (IsoView) light-sheet microscopy, which rapidly images large specimens via simultaneous light-sheet illumination and fluorescence detection along four orthogonal directions. Combining these four views by means of high-throughput multiview deconvolution yields images with high resolution in all three dimensions. We demonstrate whole-animal functional imaging of Drosophila larvae at a spatial resolution of 1.1-2.5 μm and temporal resolution of 2 Hz for several hours. We also present spatially isotropic whole-brain functional imaging in Danio rerio larvae and spatially isotropic multicolor imaging of fast cellular dynamics across gastrulating Drosophila embryos. Compared with conventional light-sheet microscopy, IsoView microscopy improves spatial resolution at least sevenfold and decreases resolution anisotropy at least threefold. Compared with existing high-resolution light-sheet techniques, IsoView microscopy effectively doubles the penetration depth and provides subsecond temporal resolution for specimens 400-fold larger than could previously be imaged.

  12. Adiabatic calorimetry test of the reaction kinetics and self-heating model for 18650 Li-ion cells in various states of charge

    Science.gov (United States)

    Chen, Wei-Chun; Wang, Yih-Wen; Shu, Chi-Min

    2016-06-01

    Use of adiabatic calorimetry to characterise thermal runaway of Li-ion cells is a crucial technique in battery safety testing. Various states of charge (SoC) of Li-ion cells were investigated to ascertain their thermal runaway features using a Vent Sizing Package 2 (VSP2) adiabatic calorimeter. To evaluate the thermal runaway characteristics, the temperature-pressure-time trajectories of commercial cylindrical cells were tested, and it was found that cells at a SoC of greater than 50% were subject to thermal explosion at elevated temperatures. Calorimetry data from various 18650 Li-ion cells with different SoC were used to calculate the thermal explosion energies and chemical kinetics; furthermore, a novel self-heating model based on a pseudo-zero-order reaction that follows the Arrhenius equation was found to be applicable for studying the exothermic reaction of a charged cell.

  13. Theoretical model of ruminant adipose tissue metabolism in relation to the whole animal.

    Science.gov (United States)

    Baldwin, R L; Yang, Y T; Crist, K; Grichting, G

    1976-09-01

    Based on theoretical considerations and experimental data, estimates of contributions of adipose tissue to energy expenditures in a lactating cow and a growing steer were developed. The estimates indicate that adipose energy expenditures range between 5 and 10% of total animal heat production dependent on productive function and diet. These energy expenditures can be partitioned among maintenance (3%), lipogenesis (1-5%) and lipolysis and triglyceride resynthesis (less thatn 1.0%). Specific sites at which acute and chronic effectors can act to produce changes in adipose function, and changes in adipose function produced by diet and during pregnancy, lactation and aging were discussed with emphasis being placed on the need for additional, definitive studies of specific interactions among pregnancy, diet, age, lactation and growth in producing ruminants.

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

    Science.gov (United States)

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

    2011-04-01

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

  15. Scintillator materials for calorimetry

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-09-01

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

  16. Dual-readout Calorimetry

    OpenAIRE

    Akchurin, N.; Bedeschi, F.; Cardini, A.; Cascella, M.; Cei, F.; Pedis, D.; Fracchia, S.; Franchino, S.; Fraternali, M.; Gaudio, G.; P. Genova; Hauptman, J.; La Rotonda, L.; Lee, S.; Livan, M.(INFN Sezione di Pavia, Pavia, Italy)

    2013-01-01

    The RD52 Project at CERN is a pure instrumentation experiment whose goal is to understand the fundamental limitations to hadronic energy resolution, and other aspects of energy measurement, in high energy calorimeters. We have found that dual-readout calorimetry provides heretofore unprecedented information event-by-event for energy resolution, linearity of response, ease and robustness of calibration, fidelity of data, and particle identification, including energy lost to binding energy in n...

  17. Calorimetry Task Force Report

    CERN Document Server

    Abdullin, Salavat; Banerjee, Sunanda; Beauceron, Stephanie; Beaudette, Florian; Bhatti, Anwar; Chlebana, Frank; Cossutti, Fabio; Hirschauer, James; Ivanchenko, V; Jang, Dong Wook; Jun, Soon Yung; Kunori, Shuichi; Kroeger, Rob; Liu, Yanwen; Moeller, Anthony; Paulini, Manfred; Piperov, Stefan; Rahmat, Rahmat; Rovelli, Chiara; Safronov, Grigory; Sharma, Seema; Spiropulu, Maria; Yetkin, Taylan

    2010-01-01

    In this note we summarize the progress made by the calorimeter simulation task force (CaloTF) over the past year. The CaloTF was established in February 2008 in order to understand and reconcile the discrepancies observed between the CMS calorimetry simulation and test beam data recorded during 2004 and 2006. The simulation has been significantly improved by using a newer version of Geant4 and an improved physics list for the full CMS detector simulation. Simulation times have been reduced by introducing flexible parameterizations to describe showering in the calorimeter (using a Gflash-like approach) which have been tuned to the test beam data.

  18. Whole-animal imaging of bacterial infection using endoscopic excitation of β-lactamase (BlaC)-specific fluorogenic probe

    Science.gov (United States)

    Nooshabadi, Fatemeh; Yang, Hee-Jeong; Cheng, Yunfeng; Xie, Hexin; Rao, Jianghong; Cirillo, Jeffrey D.; Maitland, Kristen C.

    2016-03-01

    Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains one of the most frequent causes of death worldwide. The slow growth rate of Mtb limits progress toward understanding tuberculosis including diagnosis of infections and evaluating therapeutic efficacy. Development of near-infrared (NIR) β-lactamase (BlaC)-specific fluorogenic substrate has made a significant breakthrough in the whole-animal imaging to detect Mtb infection. The reporter enzyme fluorescence (REF) system using a BlaC-specific fluorogenic substrate has improved the detection sensitivity in whole-animal optical imaging down to ~104 colony forming units (CFU) of bacteria, about 100-fold improvement over recombinant strains. However, improvement of detection sensitivity is strongly needed for clinical diagnosis of early stage infection at greater tissue depth. In order to improve detection sensitivity, we have integrated a fiber-based microendoscpe into a whole-animal imaging system to transmit the excitation light from the fiber bundle to the fluorescent target directly and measure fluorescent level using BlaC-specific REF substrate in the mouse lung. REF substrate, CNIR800, was delivered via aerosol route to the pulmonary infected mice with M. bovis BCG strain at 24 hours post-infection and groups of mice were imaged at 1-4 hours post-administration of the substrate using the integrated imaging system. In this study we evaluated the kinetics of CNIR800 substrate using REF technology using the integrated imaging system. Integration of these technologies has great promise for improved detection sensitivity allowing pre-clinical imaging for evaluation of new therapeutic agents.

  19. Dual-readout Calorimetry

    CERN Document Server

    Akchurin, N; Cardini, A.; Cascella, M.; Cei, F.; De Pedis, D.; Fracchia, S.; Franchino, S.; Fraternali, M.; Gaudio, G.; Genova, P.; Hauptman, J.; La Rotonda, L.; Lee, S.; Livan, M.; Meoni, E.; Moggi, A.; Pinci, D.; Policicchio, A.; Saraiva, J.G.; Sill, A.; Venturelli, T.; Wigmans, R.

    2013-01-01

    The RD52 Project at CERN is a pure instrumentation experiment whose goal is to un- derstand the fundamental limitations to hadronic energy resolution, and other aspects of energy measurement, in high energy calorimeters. We have found that dual-readout calorimetry provides heretofore unprecedented information event-by-event for energy resolution, linearity of response, ease and robustness of calibration, fidelity of data, and particle identification, including energy lost to binding energy in nuclear break-up. We believe that hadronic energy resolutions of {\\sigma}/E $\\approx$ 1 - 2% are within reach for dual-readout calorimeters, enabling for the first time comparable measurement preci- sions on electrons, photons, muons, and quarks (jets). We briefly describe our current progress and near-term future plans. Complete information on all aspects of our work is available at the RD52 website http://highenergy.phys.ttu.edu/dream/.

  20. Calorimetry of Nucleic Acids.

    Science.gov (United States)

    Rozners, Eriks; Pilch, Daniel S; Egli, Martin

    2015-12-01

    This unit describes the application of calorimetry to characterize the thermodynamics of nucleic acids, specifically, the two major calorimetric methodologies that are currently employed: differential scanning (DSC) and isothermal titration calorimetry (ITC). DSC is used to study thermally induced order-disorder transitions in nucleic acids. A DSC instrument measures, as a function of temperature (T), the excess heat capacity (C(p)(ex)) of a nucleic acid solution relative to the same amount of buffer solution. From a single curve of C(p)(ex) versus T, one can derive the following information: the transition enthalpy (ΔH), entropy (ΔS), free energy (ΔG), and heat capacity (ΔCp); the state of the transition (two-state versus multistate); and the average size of the molecule that melts as a single thermodynamic entity (e.g., the duplex). ITC is used to study the hybridization of nucleic acid molecules at constant temperature. In an ITC experiment, small aliquots of a titrant nucleic acid solution (strand 1) are added to an analyte nucleic acid solution (strand 2), and the released heat is monitored. ITC yields the stoichiometry of the association reaction (n), the enthalpy of association (ΔH), the equilibrium association constant (K), and thus the free energy of association (ΔG). Once ΔH and ΔG are known, ΔS can also be derived. Repetition of the ITC experiment at a number of different temperatures yields the ΔCp for the association reaction from the temperature dependence of ΔH.

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

    Science.gov (United States)

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

    2014-12-01

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

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

    Science.gov (United States)

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

    2015-09-01

    The aggregation number (n), thermodynamic potentials (ΔG, ΔH, ΔS) and critical micelle concentration (CMC) for 6 natural bile salts were determined on the basis of both original and previously published isothermal titration calorimetry (ITC) data. Different procedures to estimate parameters of micelles with ITC were compared to a mass-action model (MAM) of reaction type: n⋅S⇌Mn. This analysis can provide guidelines for future ITC studies of systems behaving in accordance with this model such as micelles and proteins that undergo self-association to oligomers. Micelles with small aggregation numbers, as those of bile salts, are interesting because such small aggregates cannot be characterized as a separate macroscopic phase and the widely applied pseudo-phase model (PPM) is inaccurate. In the present work it was demonstrated that the aggregation number of micelles was constant at low concentrations enabling determination of the thermodynamic potentials by the MAM. A correlation between the aggregation number and the heat capacity was found, which implies that the dehydrated surface area of bile salts increases with the aggregation number. This is in accordance with Tanford's principles of opposing forces where neighbouring molecules in the aggregate are better able to shield from the surrounding hydrophilic environment when the aggregation number increases. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Differential scanning calorimetry.

    Science.gov (United States)

    Spink, Charles H

    2008-01-01

    Differential scanning calorimetry (DSC) has emerged as a powerful experimental technique for determining thermodynamic properties of biomacromolecules. The ability to monitor unfolding or phase transitions in proteins, polynucleotides, and lipid assemblies has not only provided data on thermodynamic stability for these important molecules, but also made it possible to examine the details of unfolding processes and to analyze the characteristics of intermediate states involved in the melting of biopolymers. The recent improvements in DSC instrumentation and software have generated new opportunities for the study of the effects of structure and changes in environment on the behavior of proteins, nucleic acids, and lipids. This review presents some of the details of application of DSC to the examination of the unfolding of biomolecules. After a brief introduction to DSC instrumentation used for the study of thermal transitions, the methods for obtaining basic thermodynamic information from the DSC curve are presented. Then, using DNA unfolding as an example, methods for the analysis of the melting transition are presented that allow deconvolution of the DSC curves to determine more subtle characteristics of the intermediate states involved in unfolding. Two types of transitions are presented for analysis, the first example being the unfolding of two large synthetic polynucleotides, which display high cooperativity in the melting process. The second example shows the application of DSC for the study of the unfolding of a simple hairpin oligonucleotide. Details of the data analysis are presented in a simple spreadsheet format.

  4. Whole animal automated platform for drug discovery against multi-drug resistant Staphylococcus aureus.

    Science.gov (United States)

    Rajamuthiah, Rajmohan; Fuchs, Beth Burgwyn; Jayamani, Elamparithi; Kim, Younghoon; Larkins-Ford, Jonah; Conery, Annie; Ausubel, Frederick M; Mylonakis, Eleftherios

    2014-01-01

    Staphylococcus aureus, the leading cause of hospital-acquired infections in the United States, is also pathogenic to the model nematode Caenorhabditis elegans. The C. elegans-S. aureus infection model was previously carried out on solid agar plates where the bacteriovorous C. elegans feeds on a lawn of S. aureus. However, agar-based assays are not amenable to large scale screens for antibacterial compounds. We have developed a high throughput liquid screening assay that uses robotic instrumentation to dispense a precise amount of methicillin resistant S. aureus (MRSA) and worms in 384-well assay plates, followed by automated microscopy and image analysis. In validation of the liquid assay, an MRSA cell wall defective mutant, MW2ΔtarO, which is attenuated for killing in the agar-based assay, was found to be less virulent in the liquid assay. This robust assay with a Z'-factor consistently greater than 0.5 was utilized to screen the Biomol 4 compound library consisting of 640 small molecules with well characterized bioactivities. As proof of principle, 27 of the 30 clinically used antibiotics present in the library conferred increased C. elegans survival and were identified as hits in the screen. Surprisingly, the antihelminthic drug closantel was also identified as a hit in the screen. In further studies, we confirmed the anti-staphylococcal activity of closantel against vancomycin-resistant S. aureus isolates and other Gram-positive bacteria. The liquid C. elegans-S. aureus assay described here allows screening for anti-staphylococcal compounds that are not toxic to the host.

  5. Whole animal automated platform for drug discovery against multi-drug resistant Staphylococcus aureus.

    Directory of Open Access Journals (Sweden)

    Rajmohan Rajamuthiah

    Full Text Available Staphylococcus aureus, the leading cause of hospital-acquired infections in the United States, is also pathogenic to the model nematode Caenorhabditis elegans. The C. elegans-S. aureus infection model was previously carried out on solid agar plates where the bacteriovorous C. elegans feeds on a lawn of S. aureus. However, agar-based assays are not amenable to large scale screens for antibacterial compounds. We have developed a high throughput liquid screening assay that uses robotic instrumentation to dispense a precise amount of methicillin resistant S. aureus (MRSA and worms in 384-well assay plates, followed by automated microscopy and image analysis. In validation of the liquid assay, an MRSA cell wall defective mutant, MW2ΔtarO, which is attenuated for killing in the agar-based assay, was found to be less virulent in the liquid assay. This robust assay with a Z'-factor consistently greater than 0.5 was utilized to screen the Biomol 4 compound library consisting of 640 small molecules with well characterized bioactivities. As proof of principle, 27 of the 30 clinically used antibiotics present in the library conferred increased C. elegans survival and were identified as hits in the screen. Surprisingly, the antihelminthic drug closantel was also identified as a hit in the screen. In further studies, we confirmed the anti-staphylococcal activity of closantel against vancomycin-resistant S. aureus isolates and other Gram-positive bacteria. The liquid C. elegans-S. aureus assay described here allows screening for anti-staphylococcal compounds that are not toxic to the host.

  6. Unraveling the impact of hydroxylation on interactions of bile acid cationic lipids with model membranes by in-depth calorimetry studies.

    Science.gov (United States)

    Singh, Manish; Bajaj, Avinash

    2014-09-28

    We used eight bile acid cationic lipids differing in the number of hydroxyl groups and performed in-depth differential scanning calorimetry studies on model membranes doped with different percentages of these cationic bile acids. These studies revealed that the number and positioning of free hydroxyl groups on bile acids modulate the phase transition and co-operativity of membranes. Lithocholic acid based cationic lipids having no free hydroxyl groups gel well with dipalmitoylphosphatidylcholine (DPPC) membranes. Chenodeoxycholic acid lipids having one free hydroxyl group at the 7'-carbon position disrupt the membranes and lower their co-operativity. Deoxycholic acid and cholic acid based cationic lipids have free hydroxyl groups at the 12'-carbon position, and at 7'- and 12'-carbon positions respectively. Doping of these lipids at high concentrations increases the co-operativity of membranes suggesting that these lipids might induce self-assembly in DPPC membranes. These different modes of interactions between cationic lipids and model membranes would help in future for exploring their use in DNA/drug delivery.

  7. Combustion calorimetry experimental chemical thermodynamics

    CERN Document Server

    Sunner, Stig

    1979-01-01

    Combustion Calorimetry deals with expertise knowledge concerning the calorimetry of combustion reactions of an element or compound. After defining the use of units and physical constants, the book discusses the basic principles of combustion calorimetry and the various instruments and calorimeters used in the experiments to measure operations concerning temperatures and its time variations. One paper discusses the theory and design criteria of combustion calorimeter calibration. Another paper discusses the results obtained from a combustion calorimeter after it has measured the energy or entha

  8. Isosteric heat of hydrogen adsorption on MOFs: comparison between adsorption calorimetry, sorption isosteric method, and analytical models

    Science.gov (United States)

    Kloutse, A. F.; Zacharia, R.; Cossement, D.; Chahine, R.; Balderas-Xicohténcatl, R.; Oh, H.; Streppel, B.; Schlichtenmayer, M.; Hirscher, M.

    2015-12-01

    Isosteric heat of adsorption is an important parameter required to describe the thermal performance of adsorptive storage systems. It is most frequently calculated from adsorption isotherms measured over wide ranges of pressure and temperature, using the so-called adsorption isosteric method. Direct quantitative estimation of isosteric heats on the other hand is possible using the coupled calorimetric-volumetric method, which involves simultaneous measurement of heat and adsorption. In this work, we compare the isosteric heats of hydrogen adsorption on microporous materials measured by both methods. Furthermore, the experimental data are compared with the isosteric heats obtained using the modified Dubinin-Astakhov, Tóth, and Unilan adsorption analytical models to establish the reliability and limitations of simpler methods and assumptions. To this end, we measure the hydrogen isosteric heats on five prototypical metal-organic frameworks: MOF-5, Cu-BTC, Fe-BTC, MIL-53, and MOF-177 using both experimental methods. For all MOFs, we find a very good agreement between the isosteric heats measured using the calorimetric and isosteric methods throughout the range of loading studied. Models' prediction on the other hand deviates from both experiments depending on the MOF studied and the range of loading. Under low-loadings of less than 5 mol kg-1, the isosteric heat of hydrogen adsorption decreases in the order Cu-BTC > MIL-53 > MOF-5 > Fe-BTC > MOF-177. The order of isosteric heats is coherent with the strength of hydrogen interaction revealed from previous thermal desorption spectroscopy measurements.

  9. Enzyme-Directed Assembly of Nanoparticles in Tumors Monitored by In Vivo Whole Animal and Ex Vivo Super-Resolution Fluorescence Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Chien, Miao-Ping; Carlini, Andrea S.; Hu, Dehong; Barback, Christopher V.; Rush, Anthony M.; Hall, David J.; Orr, Galya; Gianneschi, Nathan C.

    2013-12-18

    Matrix metalloproteinase enzymes, overexpressed in HT-1080 human fibrocarcinoma tumors, were used to guide the accumulation and retention of an enzyme-responsive nanoparticle in a xenograft mouse model. The nanoparticles were prepared as micelles from amphiphilic block copolymers bearing a simple hydrophobic block, and a hydrophilic peptide brush. The polymers were end-labeled with Alexa Fluor 647 dyes leading to the formation of labeled micelles upon dialysis of the polymers from DMSO to aqueous buffer. This dye-labeling strategy allowed the presence of the retained material to be visualized via whole animal imaging in vivo, and in ex vivo organ analysis following intratumoral injection into HT-1080 xenograft tumors. We propose that the material is retained by virtue of an enzyme-induced accumulation process whereby particles change morphology from 20 nm spherical micelles to micron-scale aggregates, kinetically trapping them within the tumor. This hypothesis is tested here via an unprecedented super resolution fluorescence analysis of ex vivo tissue slices confirming a particle size increase occurs concomitantly with extended retention of responsive particles compared to unresponsive controls.

  10. CLARITY and PACT-based imaging of adult zebrafish and mouse for whole-animal analysis of infections

    Directory of Open Access Journals (Sweden)

    Mark R. Cronan

    2015-12-01

    Full Text Available Visualization of infection and the associated host response has been challenging in adult vertebrates. Owing to their transparency, zebrafish larvae have been used to directly observe infection in vivo; however, such larvae have not yet developed a functional adaptive immune system. Cells involved in adaptive immunity mature later and have therefore been difficult to access optically in intact animals. Thus, the study of many aspects of vertebrate infection requires dissection of adult organs or ex vivo isolation of immune cells. Recently, CLARITY and PACT (passive clarity technique methodologies have enabled clearing and direct visualization of dissected organs. Here, we show that these techniques can be applied to image host-pathogen interactions directly in whole animals. CLARITY and PACT-based clearing of whole adult zebrafish and Mycobacterium tuberculosis-infected mouse lungs enables imaging of mycobacterial granulomas deep within tissue to a depth of more than 1 mm. Using established transgenic lines, we were able to image normal and pathogenic structures and their surrounding host context at high resolution. We identified the three-dimensional organization of granuloma-associated angiogenesis, an important feature of mycobacterial infection, and characterized the induction of the cytokine tumor necrosis factor (TNF within the granuloma using an established fluorescent reporter line. We observed heterogeneity in TNF induction within granuloma macrophages, consistent with an evolving view of the tuberculous granuloma as a non-uniform, heterogeneous structure. Broad application of this technique will enable new understanding of host-pathogen interactions in situ.

  11. Experimental chemical thermodynamics. Volume I. Combustion calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Sunner, S.; Mansson, M. (eds.)

    1979-01-01

    This book contains 18 chapters. The information included is: units and physical constants; basic principles of combustion calorimetry; calibration of combustion calorimeters; test and auxiliary substances in combustion calorimetry; strategies in the calculation of standard-state energies of combustion from the experimentally determined quantities; assignments of uncertainties; presentation of combustion calorimetric data in the primary literature; general techniques for combustion of liquid/solid organic compounds by oxygen bomb calorimetry; combustion of liquid/solid organic compounds with non-metallic hetero-atoms; combustion calorimetry of metals and simple metallic compounds; combustion calorimetry of organometallic compounds; combustion in fluorine and other halogens; bomb combustion of gaseous compounds in oxygen; oxygen flame calorimetry; fluorine flame calorimetry; combustion calorimetry as a technological service; trends in combustion calorimetry; and from the history of combustion calorimetry. (DP)

  12. Comparison of whole animal costs of protein synthesis among polar and temperate populations of the same species of gammarid amphipod.

    Science.gov (United States)

    Rastrick, S P S; Whiteley, N M

    2017-05-01

    Protein synthesis can account for a substantial proportion of metabolic rate. Energetic costs of protein synthesis, should in theory, be the same in marine invertebrates from a range of thermal habitats, and yet direct measurements using inhibitors produce widely differing values, especially in the cold. The present study aimed to remove any potential confounding interspecific effects by determining costs of protein synthesis in two latitudinally separated populations of the same species (amphipod, Gammarus oceanicus) living in two different thermal regimes; polar vs cold-temperate. Costs of protein synthesis were determined in summer acclimatised G. oceanicus from Svalbard (79°N) at 5°C and from Scotland (58°N) at 13°C. Amphipods were injected with the protein synthesis inhibitor, cycloheximide (CHX), at 9mmoll(-1) in crab saline to give a tissue concentration of 0.05mgCHXg(-1)FW and left for 60min before the injection of [(3)H] phenylalanine. After incubation for 120min (180min in total from initial injection), both whole-animal rates of oxygen uptake and absolute rates of protein synthesis were significantly reduced in CHX-treated amphipods vs controls injected with saline. Both populations exhibited similar costs of protein synthesis of ~7μmolO2mg(-1)protein which is close to the estimated theoretical minimum for peptide bond formation, and similar to the values obtained in cell-free systems. The study demonstrates that in G. oceanicus, costs of protein synthesis rates were not elevated in the cold but were fixed among polar and cold-temperate populations. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Calorimetry at industrial electron accelerators

    DEFF Research Database (Denmark)

    Miller, Arne; Kovacs, A.

    1985-01-01

    Calorimetry is a convenient way to measure doses at industrial electron accelerators, where high absorbed doses (1-100 kGy) are delivered at dose rates of 102-105 Gy s-1 or even higher. Water calorimeters have been used for this purpose for several years, but recently other materials such as grap......Calorimetry is a convenient way to measure doses at industrial electron accelerators, where high absorbed doses (1-100 kGy) are delivered at dose rates of 102-105 Gy s-1 or even higher. Water calorimeters have been used for this purpose for several years, but recently other materials...

  14. Calorimetry at industrial electron accelerators

    DEFF Research Database (Denmark)

    Miller, Arne; Kovacs, A.

    1985-01-01

    Calorimetry is a convenient way to measure doses at industrial electron accelerators, where high absorbed doses (1-100 kGy) are delivered at dose rates of 102-105 Gy s-1 or even higher. Water calorimeters have been used for this purpose for several years, but recently other materials such as grap......Calorimetry is a convenient way to measure doses at industrial electron accelerators, where high absorbed doses (1-100 kGy) are delivered at dose rates of 102-105 Gy s-1 or even higher. Water calorimeters have been used for this purpose for several years, but recently other materials...

  15. Contactless Calorimetry for Levitated Samples

    Science.gov (United States)

    Lee, M. C.; Dokko, W.

    1986-01-01

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

  16. Effects of convenience rice congee supplemented diets on guinea pig whole animal and gut growth, caecal digesta SCFA and in vitro ileal contractility.

    Science.gov (United States)

    Patten, Glen S; Bird, Anthony R; Topping, David L; Abeywardena, Mahinda Y

    2004-01-01

    The aim of the study was to feed convenience baby food brown rice (BC) and white rice (WC) congee diets compared to egg custard (EC) and baked bean (BB) diets to newborn guinea pig pups. Diets were isocaloric and formulated to contain equal macronutrient content of carbohydrate, protein, fat and fibre. Diets were supplemented with essential nutrients, fruit and vegetables and decrementally with standard chow for palatability. We investigated the acceptability of the diets and specifically whether the different natural fibre content of these diets could influence whole animal and small intestinal growth, caecal digesta properties and specifically in vitro ileal contractility. After 8 weeks of feeding, the mean body weight of WC group was significantly lower than the BB group. WC group had lower small intestine weight than both BC group and BB group resulting in lower small intestine density compared to BB group. Caecal digesta pH and total short chain fatty acid (SCFA) concentration were similar. However, butyrate was higher in the BB group compared to the other diets. Contractility studies revealed a small but significantly higher voltage was required to initiate ileal contraction of BC group compared to both the EC and BB groups. All dietary groups responded similarly to acetylcholine, histamine, serotonin, PGE(2), PGF(2alpha), and 8-iso-PGE(2). There were no differences on inhibition of electrically-driven contraction by morphine or epinephrine. The newborn guinea pig model was an effective system for testing, with limitations, supplemented convenience baby foods with variable natural fibre content that demonstrated significant effects on animal growth, caecal digesta SCFA and intestinal contractility.

  17. Calorimetry fundamentals, instrumentation and applications

    CERN Document Server

    Sarge, Stefan M; Hemminger, Wolfgang

    2014-01-01

    Clearly divided into three parts, this practical book begins by dealing with all fundamental aspects of calorimetry. The second part looks at the equipment used and new developments. The third and final section provides measurement guidelines in order to obtain the best results. The result is optimized knowledge for users of this technique, supplemented with practical tips and tricks.

  18. Calorimetry triggering in ATLAS

    CERN Document Server

    Igonkina, O; Adragna, P; Aharrouche, M; Alexandre, G; Andrei, V; Anduaga, X; Aracena, I; Backlund, S; Baines, J; Barnett, B M; Bauss, B; Bee, C; Behera, P; Bell, P; Bendel, M; Benslama, K; Berry, T; Bogaerts, A; Bohm, C; Bold, T; Booth, J R A; Bosman, M; Boyd, J; Bracinik, J; Brawn, I, P; Brelier, B; Brooks, W; Brunet, S; Bucci, F; Casadei, D; Casado, P; Cerri, A; Charlton, D G; Childers, J T; Collins, N J; Conde Muino, P; Coura Torres, R; Cranmer, K; Curtis, C J; Czyczula, Z; Dam, M; Damazio, D; Davis, A O; De Santo, A; Degenhardt, J; Delsart, P A; Demers, S; Demirkoz, B; Di Mattia, A; Diaz, M; Djilkibaev, R; Dobson, E; Dova, M, T; Dufour, M A; Eckweiler, S; Ehrenfeld, W; Eifert, T; Eisenhandler, E; Ellis, N; Emeliyanov, D; Enoque Ferreira de Lima, D; Faulkner, P J W; Ferland, J; Flacher, H; Fleckner, J E; Flowerdew, M; Fonseca-Martin, T; Fratina, S; Fhlisch, F; Gadomski, S; Gallacher, M P; Garitaonandia Elejabarrieta, H; Gee, C N P; George, S; Gillman, A R; Goncalo, R; Grabowska-Bold, I; Groll, M; Gringer, C; Hadley, D R; Haller, J; Hamilton, A; Hanke, P; Hauser, R; Hellman, S; Hidvgi, A; Hillier, S J; Hryn'ova, T; Idarraga, J; Johansen, M; Johns, K; Kalinowski, A; Khoriauli, G; Kirk, J; Klous, S; Kluge, E-E; Koeneke, K; Konoplich, R; Konstantinidis, N; Kwee, R; Landon, M; LeCompte, T; Ledroit, F; Lei, X; Lendermann, V; Lilley, J N; Losada, M; Maettig, S; Mahboubi, K; Mahout, G; Maltrana, D; Marino, C; Masik, J; Meier, K; Middleton, R P; Mincer, A; Moa, T; Monticelli, F; Moreno, D; Morris, J D; Mller, F; Navarro, G A; Negri, A; Nemethy, P; Neusiedl, A; Oltmann, B; Olvito, D; Osuna, C; Padilla, C; Panes, B; Parodi, F; Perera, V J O; Perez, E; Perez Reale, V; Petersen, B; Pinzon, G; Potter, C; Prieur, D P F; Prokishin, F; Qian, W; Quinonez, F; Rajagopalan, S; Reinsch, A; Rieke, S; Riu, I; Robertson, S; Rodriguez, D; Rogriquez, Y; Rhr, F; Saavedra, A; Sankey, D P C; Santamarina, C; Santamarina Rios, C; Scannicchio, D; Schiavi, C; Schmitt, K; Schultz-Coulon, H C; Schfer, U; Segura, E; Silverstein, D; Silverstein, S; Sivoklokov, S; Sjlin, J; Staley, R J; Stamen, R; Stelzer, J; Stockton, M C; Straessner, A; Strom, D; Sushkov, S; Sutton, M; Tamsett, M; Tan, C L A; Tapprogge, S; Thomas, J P; Thompson, P D; Torrence, E; Tripiana, M; Urquijo, P; Urrejola, P; Vachon, B; Vercesi, V; Vorwerk, V; Wang, M; Watkins, P M; Watson, A; Weber, P; Weidberg, T; Werner, P; Wessels, M; Wheeler-Ellis, S; Whiteson, D; Wiedenmann, W; Wielers, M; Wildt, M; Winklmeier, F; Wu, X; Xella, S; Zhao, L; Zobernig, H; de Seixas, J M; dos Anjos, A; Asman, B; Özcan, E

    2009-01-01

    The ATLAS experiment is preparing for data taking at 14 TeV collision energy. A rich discovery physics program is being prepared in addition to the detailed study of Standard Model processes which will be produced in abundance. The ATLAS multi-level trigger system is designed to accept one event in 2 105 to enable the selection of rare and unusual physics events. The ATLAS calorimeter system is a precise instrument, which includes liquid Argon electro-magnetic and hadronic components as well as a scintillator-tile hadronic calorimeter. All these components are used in the various levels of the trigger system. A wide physics coverage is ensured by inclusively selecting events with candidate electrons, photons, taus, jets or those with large missing transverse energy. The commissioning of the trigger system is being performed with cosmic ray events and by replaying simulated Monte Carlo events through the trigger and data acquisition system.

  19. Indirect calorimetry during incubation of hatching eggs

    NARCIS (Netherlands)

    Brand, van den H.; Heetkamp, M.J.W.; Kemp, B.

    2015-01-01

    Indirect calorimetry can be used during incubation of avian eggs to monitor the quality of the incubation process, the development of the embryo and the utilization of nutrients. Indirect calorimetry has several benefits above direct calorimetry, particularly in hatching eggs. However, to obtain rel

  20. Differential scanning calorimetry of coal

    Science.gov (United States)

    Gold, P. I.

    1978-01-01

    Differential scanning calorimetry studies performed during the first year of this project demonstrated the occurrence of exothermic reactions associated with the production of volatile matter in or near the plastic region. The temperature and magnitude of the exothermic peak were observed to be strongly affected by the heating rate, sample mass and, to a lesser extent, by sample particle size. Thermal properties also were found to be influenced by oxidation of the coal sample due to weathering effects.

  1. Calorimetry of non-reacting systems

    CERN Document Server

    McCullough, John P

    2013-01-01

    Experimental Thermodynamics, Volume 1: Calorimetry of Non-Reacting Systems covers the heat capacity determinations for chemical substances in the solid, liquid, solution, and vapor states, at temperatures ranging from near the absolute zero to the highest at which calorimetry is feasible.This book is divided into 14 chapters. The first four chapters provide background information and general principles applicable to all types of calorimetry of non-reacting systems. The remaining 10 chapters deal with specific types of calorimetry. Most of the types of calorimetry treated are developed over a c

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

    Science.gov (United States)

    Kaiyala, Karl J.; Ramsay, Douglas S.

    2012-01-01

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

  3. Micromegas for imaging hadronic calorimetry

    CERN Document Server

    Adloff, C; Cap, S; Chefdeville, M; Dalmaz, A; Drancourt, C; Espargiliere, A; Gaglione, R; Gallet, R; Geffroy, N; Jacquemier, J; Karyotakis, Y; Peltier, F; Prast, J; Vouters, G

    2011-01-01

    The recent progress in R&D of the Micromegas detectors for hadronic calorimetry including new engineering-technical solutions, electronics development, and accompanying simulation studies with emphasis on the comparison of the physics performance of the analog and digital readout is described. The developed prototypes are with 2 bit digital readout to exploit the Micromegas proportional mode and thus improve the calorimeter linearity. In addition, measurements of detection efficiency, hit multiplicity, and energy shower profiles obtained during the exposure of small size prototypes to radioactive source quanta, cosmic particles and accelerator beams are reported. Eventually, the status of a large scale chamber (1{\\times}1 m2) are also presented with prospective towards the construction of a 1 m3 digital calorimeter consisting of 40 such chambers.

  4. Development of Quartz Fiber Calorimetry

    CERN Multimedia

    2002-01-01

    % RD40 \\\\ \\\\ Very Forward Calorimeters (VFCs) in LHC detectors should cover the pseudorapidity range from $\\eta$~=~2.5 to at least $\\eta$~=~5 in order to compute missing transverse energy and for jet tagging. Operation at such high rapidity requires the use of a calorimetry technique that is very radiation resistant, fast and insensitive to radioactivity (especially to neutrons). This can be accomplished through the Quartz-Calorimeter~(Q-Cal) concept of embedding silica core fibers, that resist to the Gigarad radiation level, into an absorber. In this calorimeter the shower particles produce light through the Cherenkov effect generating a signal less than 10~ns in duration. Unique to this new technology the visible energy of hadronic showers has a transverse dimension nearly an order of magnitude smaller than that in conventional calorimeters, enabling precise spatial resolution, sharper isolation cuts and better jet recognition against the minimum bias events background. Last but not least, most radioactive ...

  5. On the Interpretation of Low Temperature Calorimetry Data

    DEFF Research Database (Denmark)

    Kjeldsen, Ane Mette; Geiker, Mette Rica

    2008-01-01

    The effect of selected factors and phenomena on Low Temperature Calorimetry (LTC) results has been investigated, in order to determine the possibilities and limitations of using LTC for characterisation of the porosity of cement-based materials. LTC was carried out on a model material with mono...

  6. Isothermal calorimetry on enzymatic biodiesel production

    DEFF Research Database (Denmark)

    Fjerbæk, Lene

    2008-01-01

    conditions can not be elucidated. These effects have been observed with isothermal calorimetry bringing forth new information about the reaction of enzymes catalyzing transesterification. Enzymatic biodiesel production has until now not been investigated with isothermal microcalorimetry, but the results...... and potential of the technique used for investigations of complex and heterogeneous substrates are presented and discussed in the presentation. Reference List 1 Bianconi,M.L. (2007) Calorimetry of enzyme-catalyzed reactions.  Biophysical Chemistry, 126, 59-64. 2 Todd,M.J. and Gomez,J. (2001) Enzyme Kinetics...... Determined Using Calorimetry: A General Assay for Enzyme Activity?  Analytical Biochemistry, 296, 179-187....

  7. Predicting chronic copper and nickel reproductive toxicity to Daphnia pulex-pulicaria from whole-animal metabolic profiles.

    Science.gov (United States)

    Taylor, Nadine S; Kirwan, Jennifer A; Johnson, Craig; Yan, Norman D; Viant, Mark R; Gunn, John M; McGeer, James C

    2016-05-01

    The emergence of omics approaches in environmental research has enhanced our understanding of the mechanisms underlying toxicity; however, extrapolation from molecular effects to whole-organism and population level outcomes remains a considerable challenge. Using environmentally relevant, sublethal, concentrations of two metals (Cu and Ni), both singly and in binary mixtures, we integrated data from traditional chronic, partial life-cycle toxicity testing and metabolomics to generate a statistical model that was predictive of reproductive impairment in a Daphnia pulex-pulicaria hybrid that was isolated from an historically metal-stressed lake. Furthermore, we determined that the metabolic profiles of organisms exposed in a separate acute assay were also predictive of impaired reproduction following metal exposure. Thus we were able to directly associate molecular profiles to a key population response - reproduction, a key step towards improving environmental risk assessment and management.

  8. Recent Work on Calorimetry at LANL

    Energy Technology Data Exchange (ETDEWEB)

    Santi, Peter A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hauck, Danielle K. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-01-09

    This report is a briefing to collaborators at the Swedish Nuclear Fuel and Waste Management Company, Oskarshamn, Sweden, January 14, 2014. It describes the way in which calorimetry supports the safegurard mission.

  9. Automatic calorimetry system monitors RF power

    Science.gov (United States)

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

    1969-01-01

    Calorimetry system monitors the average power dissipated in a high power RF transmitter. Sensors measure the change in temperature and the flow rate of the coolant, while a multiplier computes the power dissipated in the RF load.

  10. Differential scanning calorimetry of protein-lipid interactions.

    Science.gov (United States)

    Cañadas, Olga; Casals, Cristina

    2013-01-01

    Differential scanning calorimetry (DSC) is a highly sensitive non-perturbing technique for measuring the thermodynamic properties of thermally induced transitions. This technique is particularly useful for the characterization of lipid/protein interactions. This chapter presents an introduction to DSC instrumentation, basic theory, and methods and describes DSC applications for characterizing protein effects on model lipid membranes. Examples of the use of DSC for the evaluation of protein effects on modulation of membrane domains and membrane stability are given.

  11. In vitro model of infected stratum corneum for the efficacy evaluation of poloxamer 407-based formulations of ciclopirox olamine against Trichophyton rubrum as well as differential scanning calorimetry and stability studies.

    Science.gov (United States)

    Täuber, Anja; Müller-Goymann, Christel C

    2015-10-15

    Superficial fungal skin infections are a common disease and concern 20-25% of the world's population with the dermatophyte Trichophyton rubrum being the main trigger. Due to autoinoculation, fungal skin infections of the feet (tinea pedis) often occur simultaneously with fungal nail infections (onychomycosis). Therefore, the overall objective was the development and characterisation of poloxamer 407-based formulations with the antimycotic active ingredient ciclopirox olamine (CPX) for simultaneous antifungal therapy. The formulations consisted of poloxamer 407, water, isopropyl alcohol, propylene glycol and medium chain triglycerides in given ratios. The in vitro antifungal efficacy against T. rubrum was tested in a novel in vitro model of infected stratum corneum in comparison to a marketed semi-solid formulation containing 1% (w/w) ciclopirox olamine and a marketed nail lacquer containing 8% ciclopirox. Several liquid poloxamer 407-based formulations with only 1% CPX completely inhibited fungal growth after 6 days of incubation, whereas the marketed semi-solid formulation did not inhibit fungal growth. Differential scanning calorimetry studies revealing the interaction between the formulations and the SC showed that increasing isopropyl alcohol/propylene glycol concentrations as well as increasing CPX concentrations caused increasing endothermic transition shifts. Moreover, stability studies at 30 °C exhibited only a slight decrease of the CPX amount after 12 months of storage. Each formulation contained >90% of the initial CPX concentration after termination of the stability studies.

  12. The Simulation of the ATLAS Liquid Argon Calorimetry

    CERN Document Server

    Archambault, J P; Carli, T; Costanzo, D; Dell'Acqua, A; Djama, F; Gallas, M; Fincke-Keeler, M; Khakzad, M; Kiryunin, A; Krieger, P; Leltchouk, M; Loch, P; Ma, H; Menke, S; Monnier, E; Nairz, A; Niess, V; Oakham, G; Oram, C; Pospelov, G; Rajagopalan, S; Rimoldi, A; Rousseau, D; Rutherfoord, J; Seligman, W; Soukharev, A; Strízenec, P; Tóth, J; Tsukerman, I; Tsulaia, V; Unal, G; Grahn, K J

    2008-01-01

    In ATLAS, all of the electromagnetic calorimetry and part of the hadronic calorimetry is performed by a calorimeter system using liquid argon as the active material, together with various types of absorbers. The liquid argon calorimeter consists of four subsystems: the electromagnetic barrel and endcap accordion calorimeters; the hadronic endcap calorimeters, and the forward calorimeters. A very accurate geometrical description of these calorimeters is used as input to the Geant 4-based ATLAS simulation, and a careful modelling of the signal development is applied in the generation of hits. Certain types of Monte Carlo truth information ("Calibration Hits") may, additionally, be recorded for calorimeter cells as well as for dead material. This note is a comprehensive reference describing the simulation of the four liquid argon calorimeteter components.

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

    Science.gov (United States)

    Kaiyala, Karl J; Ramsay, Douglas S

    2011-03-01

    Direct animal calorimetry, the gold standard method for quantifying animal heat production (HP), has been largely supplanted by respirometric indirect calorimetry owing to the relative ease and ready commercial availability of the latter technique. Direct calorimetry, however, can accurately quantify HP and thus metabolic rate (MR) in both metabolically normal and abnormal states, whereas respirometric indirect calorimetry relies on important assumptions that apparently have never been tested in animals with genetic or pharmacologically-induced alterations that dysregulate metabolic fuel partitioning and storage so as to promote obesity and/or diabetes. Contemporary obesity and diabetes research relies heavily on metabolically abnormal animals. Recent data implicating individual and group variation in the gut microbiome in obesity and diabetes raise important questions about transforming aerobic gas exchange into HP because 99% of gut bacteria are anaerobic and they outnumber eukaryotic cells in the body by ∼10-fold. Recent credible work in non-standard laboratory animals documents substantial errors in respirometry-based estimates of HP. Accordingly, it seems obvious that new research employing simultaneous direct and indirect calorimetry (total calorimetry) will be essential to validate respirometric MR phenotyping in existing and future pharmacological and genetic models of obesity and diabetes. We also detail the use of total calorimetry with simultaneous core temperature assessment as a model for studying homeostatic control in a variety of experimental situations, including acute and chronic drug administration. Finally, we offer some tips on performing direct calorimetry, both singly and in combination with indirect calorimetry and core temperature assessment. Copyright © 2010 Elsevier Inc. All rights reserved.

  14. Calorimetry energy measurement in particle physics

    CERN Document Server

    Wigmans, Richard

    2017-01-01

    Particle physics is the science that pursues the age-old quest for the innermost structure of matter and the fundamental interactions between its constituents. Modern experiments in this field rely increasingly on calorimetry, a detection technique in which the particles of interest are absorbed in the detector. Calorimeters are very intricate instruments. Their performance characteristics depend on subtle, sometimes counter-intuitive design details. This book, written by one of the world's foremost experts, is the first comprehensive text on this topic. It provides a fundamental and systematic introduction to calorimetry. It describes the state of the art in terms of both the fundamental understanding of calorimetric particle detection, and the actual detectors that have been or are being built and operated in experiments. The last chapter discusses landmark scientific discoveries in which calorimetry has played an important role. This book summarizes and puts into perspective the work described in some 900...

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

    Science.gov (United States)

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

    2014-07-15

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

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

    Science.gov (United States)

    Schick, C

    2009-11-01

    Differential scanning calorimetry (DSC) is an effective analytical tool to characterize the physical properties of a polymer. DSC enables determination of melting, crystallization, and mesomorphic transition temperatures, and the corresponding enthalpy and entropy changes, and characterization of glass transition and other effects that show either changes in heat capacity or a latent heat. Calorimetry takes a special place among other methods. In addition to its simplicity and universality, the energy characteristics (heat capacity C(P) and its integral over temperature T--enthalpy H), measured via calorimetry, have a clear physical meaning even though sometimes interpretation may be difficult. With introduction of differential scanning calorimeters (DSC) in the early 1960s calorimetry became a standard tool in polymer science. The advantage of DSC compared with other calorimetric techniques lies in the broad dynamic range regarding heating and cooling rates, including isothermal and temperature-modulated operation. Today 12 orders of magnitude in scanning rate can be covered by combining different types of DSCs. Rates as low as 1 microK s(-1) are possible and at the other extreme heating and cooling at 1 MK s(-1) and higher is possible. The broad dynamic range is especially of interest for semicrystalline polymers because they are commonly far from equilibrium and phase transitions are strongly time (rate) dependent. Nevertheless, there are still several unsolved problems regarding calorimetry of polymers. I try to address a few of these, for example determination of baseline heat capacity, which is related to the problem of crystallinity determination by DSC, or the occurrence of multiple melting peaks. Possible solutions by using advanced calorimetric techniques, for example fast scanning and high frequency AC (temperature-modulated) calorimetry are discussed.

  17. Calorimetry and thermal methods in catalysis

    CERN Document Server

    Auroux, Aline

    2013-01-01

    The book is about calorimetry and thermal analysis methods, alone or linked to other techniques, as applied to the characterization of catalysts, supports and adsorbents, and to the study of catalytic reactions in various domains: air and wastewater treatment, clean and renewable energies, refining of hydrocarbons, green chemistry, hydrogen production and storage. The book is intended to fill the gap between the basic thermodynamic and kinetics concepts acquired by students during their academic formation, and the use of experimental techniques such as thermal analysis and calorimetry to answ

  18. Isothermal Titration Calorimetry in the Student Laboratory

    Science.gov (United States)

    Wadso, Lars; Li, Yujing; Li, Xi

    2011-01-01

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

  19. Isothermal calorimetry of enzymatic biodiesel reaction

    DEFF Research Database (Denmark)

    Fjerbæk Søtoft, Lene; Westh, Peter; Christensen, Knud Villy

    2010-01-01

      Isothermal calorimetry ITC has been used to investigate enzymatic biodiesel production. The transesterification of rapeseed oil with methanol and ethanol was catalyzed by the immobilized lipase Novozym 435 at 40°C. The ITC-experiments clearly demonstrate the possibilities of investigating complex...

  20. Isothermal Titration Calorimetry in the Student Laboratory

    Science.gov (United States)

    Wadso, Lars; Li, Yujing; Li, Xi

    2011-01-01

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

  1. Calculation of Temperature Rise in Calorimetry.

    Science.gov (United States)

    Canagaratna, Sebastian G.; Witt, Jerry

    1988-01-01

    Gives a simple but fuller account of the basis for accurately calculating temperature rise in calorimetry. Points out some misconceptions regarding these calculations. Describes two basic methods, the extrapolation to zero time and the equal area method. Discusses the theoretical basis of each and their underlying assumptions. (CW)

  2. Final Technical Report CMS fast optical calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Winn, David R. [Fairfield Univ., CT (United States)

    2012-07-12

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

  3. Study of asphaltene precipitation by Calorimetry

    DEFF Research Database (Denmark)

    Verdier, Sylvain Charles Roland; Plantier, Frédéric; Bessières, David;

    2007-01-01

    of experiments showed that weak forces determine precipitation. Indeed, isothermal titration calorimetry could not detect any clear signal although this technique can detect low-energy transitions such as liquid-liquid equilibrium and rnicellization. The second series of tests proved that precipitation caused...

  4. HDTHe calorimetry v.1.0

    Energy Technology Data Exchange (ETDEWEB)

    2016-01-12

    The software generates predicted results of differential scanning calorimetry experiments for samples of palladium in a perforated capsule in an atmosphere containing a mixture of hydrogen isotopologues and helium. It can also be used to predict the results of absorption-desorption experiments at constant temperature and solid-phase isotopic ratio.

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

    Science.gov (United States)

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

    2009-01-01

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

  6. Enzyme-catalyzed and binding reaction kinetics determined by titration calorimetry.

    Science.gov (United States)

    Hansen, Lee D; Transtrum, Mark K; Quinn, Colette; Demarse, Neil

    2016-05-01

    Isothermal calorimetry allows monitoring of reaction rates via direct measurement of the rate of heat produced by the reaction. Calorimetry is one of very few techniques that can be used to measure rates without taking a derivative of the primary data. Because heat is a universal indicator of chemical reactions, calorimetry can be used to measure kinetics in opaque solutions, suspensions, and multiple phase systems and does not require chemical labeling. The only significant limitation of calorimetry for kinetic measurements is that the time constant of the reaction must be greater than the time constant of the calorimeter which can range from a few seconds to a few minutes. Calorimetry has the unique ability to provide both kinetic and thermodynamic data. This article describes the calorimetric methodology for determining reaction kinetics and reviews examples from recent literature that demonstrate applications of titration calorimetry to determine kinetics of enzyme-catalyzed and ligand binding reactions. A complete model for the temperature dependence of enzyme activity is presented. A previous method commonly used for blank corrections in determinations of equilibrium constants and enthalpy changes for binding reactions is shown to be subject to significant systematic error. Methods for determination of the kinetics of enzyme-catalyzed reactions and for simultaneous determination of thermodynamics and kinetics of ligand binding reactions are reviewed. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Foward Calorimetry in ALICE at LHC

    Science.gov (United States)

    Chujo, Tatsuya; Alice Focal Collaboration

    2014-09-01

    We present an upgrade proposal for calorimetry in the forward direction, FOCAL, to measure direct photons in η = 3 . 3 - 5 . 3 in ALICE at the Large Hadron Collider (LHC). We suggest to use an electromagnetic calorimeter based on the novel technology of silicon sensors with W absorbers for photons, together with a conventional hadron calorimeter for jet measurements and photon isolation. The current status of the FOCAL R&D project will be presented.

  8. Calibration and monitoring for crystal calorimetry

    CERN Document Server

    Zhu, Ren Yuan

    2005-01-01

    Crystal calorimetry provides excellent energy resolution in high energy and nuclear physics. The light output of heavy crystal scintillators, however, suffers from not negligible damage in radiation environment. A precision calibration and monitoring thus is crucial for maintaining crystal precision in situ. The performance of calibration and monitoring approaches used by BaBar, CLEO and L3 experiments are presented. The design and construction of a laser- based light monitoring system for CMS PWO calorimeter is also discussed.

  9. Crystallization behavior of biodiesel based on differential scanning calorimetry and thermodynamic model%基于差示扫描量热法和热力学模型的生物柴油结晶行为分析

    Institute of Scientific and Technical Information of China (English)

    梅德清; 谭文兵; 张永涛; 袁银男

    2014-01-01

    棕榈酸甲酯(C16:0)、硬脂酸甲酯(C18:0)和油酸甲酯(C18:1)是生物柴油的主要组成部分。为了深入探究生物柴油的结晶行为,该文基于差示扫描量热法(differential scanning calorimetry, DSC)分析了这3种脂肪酸酯的物性参数,研究发现饱和脂肪酸甲酯 C16:0和 C18:0的熔点和熔化焓远远高出不饱和脂肪酸甲酯 C18:1的值,C16:0和C18:0的熔点分别为301.57、310.92 K,C18:1的熔点为255.01 K。对脂肪酸酯组成的二元溶液进行DSC扫描, DSC曲线出现了2个放热峰,并且溶液的结晶点要低于首先析出的饱和脂肪酸酯纯物质时的熔点;随着饱和脂肪酸酯质量分数的增加溶液的结晶点温度也相应提高。将生物柴油当作由多元脂肪酸甲酯的混合溶液时,C16:0和C18:0等饱和脂肪酸甲酯作为溶质,C18:1等不饱和脂肪酸甲酯作为溶剂,建立了热力学模型计算溶液的结晶点温度。将脂肪酸甲酯的混合溶液近似为理想溶液时对此模型进一步简化,并利用简化模型计算得到4种生物柴油的结晶温度,与实测值进行比较得到了很好的验证效果。该研究可为优化生物柴油低温流动性的技术措施提供参考。%Biodiesel, as a renewable alternative fuel, is easily crystallized at low temperature, which limits the application of engines fueled with biodiesel. Biodiesel is mainly composed of methyl palmitate (C16:0), methyl stearate (C18:0) and methyl oleate (C18:1). The properties of fuel are closely related to the properties of its compositions, and the fuel properties will change with different mole fraction ratios of some composition. So, it is very important to research the thermal parameters of different compositions. Differential scanning calorimetry (DSC) is a thermo analytical technique by which the difference in the amount of heat required to increase the temperature of a sample and reference is measured as a

  10. Scintillating Fibre Calorimetry at the LHC

    CERN Multimedia

    2002-01-01

    Good electromagnetic and hadronic calorimetry will play a central role in an LHC detector. The lead/scintillating fibre calorimeter technique provides a fast signal response well matched to the LHC rate requirements. It can be made to give equal response for electrons and hadrons (compensation) with good electromagnetic and hadronic energy resolutions.\\\\ \\\\ The aim of this R&D proposal is to study in detail the aspects that are relevant for application of this type of calorimeter in an LHC environment, including its integration in a larger system of detectors, e.g.~projective geometry, radiation hardness, light detection, calibration and stability monitoring, electron/hadron separation.....

  11. Isothermal calorimetry of enzymatic biodiesel reaction

    DEFF Research Database (Denmark)

    Fjerbæk Søtoft, Lene; Westh, Peter; Christensen, Knud Villy

    2010-01-01

      Isothermal calorimetry ITC has been used to investigate enzymatic biodiesel production. The transesterification of rapeseed oil with methanol and ethanol was catalyzed by the immobilized lipase Novozym 435 at 40°C. The ITC-experiments clearly demonstrate the possibilities of investigating complex...... and composition change in the system, the heat of reaction at 40°C for the two systems has been determined to -9.8 ± 0.9 kJ/mole biodiesel formed from rapeseed oil and methanol, and - 9.3 ± 0.7 kJ/mole when rapeseed oil and ethanol is used....

  12. Standard Procedure for Calibrating an Areal Calorimetry Based Dosimeter

    Science.gov (United States)

    2015-05-01

    2015 AFRL-RH-FS-TR-2015-0013 Standard Procedure for Calibrating an Areal Calorimetry Based Dosimeter Charles W. Beason Devon Ryan...0013 "Standard Procedure for Calibrating an Areal Calorimetry Based Dosimeter" TR LELAND JOHNSON, DR-III, DAF Contract Monitor Radio Frequency...Calibrating an Areal Calorimetry Based Dosimeter 5b. GRANT NUMBER N/A 5c. PROGRAM ELEMENT NUMBER 62202F 6. AUTHOR(S) 5d. PROJECT NUMBER N/A Charles W

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

    Science.gov (United States)

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

    2009-03-15

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

  14. Pressure perturbation calorimetry of unfolded proteins.

    Science.gov (United States)

    Tsamaloukas, Alekos D; Pyzocha, Neena K; Makhatadze, George I

    2010-12-16

    We report the application of pressure perturbation calorimetry (PPC) to study unfolded proteins. Using PPC we have measured the temperature dependence of the thermal expansion coefficient, α(T), in the unfolded state of apocytochrome C and reduced BPTI. We have shown that α(T) is a nonlinear function and decreases with increasing temperature. The decrease is most significant in the low (2-55 °C) temperature range. We have also tested an empirical additivity approach to predict α(T) of unfolded state from the amino acid sequence using α(T) values for individual amino acids. A comparison of the experimental and calculated functions shows a very good agreement, both in absolute values of α(T) and in its temperature dependence. Such an agreement suggests the applicability of using empirical calculations to predict α(T) of any unfolded protein.

  15. Higher Throughput Calorimetry: Opportunities, Approaches and Challenges

    Science.gov (United States)

    Recht, Michael I.; Coyle, Joseph E.; Bruce, Richard H.

    2010-01-01

    Higher throughput thermodynamic measurements can provide value in structure-based drug discovery during fragment screening, hit validation, and lead optimization. Enthalpy can be used to detect and characterize ligand binding, and changes that affect the interaction of protein and ligand can sometimes be detected more readily from changes in the enthalpy of binding than from the corresponding free-energy changes or from protein-ligand structures. Newer, higher throughput calorimeters are being incorporated into the drug discovery process. Improvements in titration calorimeters come from extensions of a mature technology and face limitations in scaling. Conversely, array calorimetry, an emerging technology, shows promise for substantial improvements in throughput and material utilization, but improved sensitivity is needed. PMID:20888754

  16. Isothermal Titration Calorimetry to Characterize Enzymatic Reactions.

    Science.gov (United States)

    Mazzei, Luca; Ciurli, Stefano; Zambelli, Barbara

    2016-01-01

    Isothermal titration calorimetry (ITC) is a technique that measures the heat released or absorbed during a chemical reaction as an intrinsic probe to characterize any chemical process that involves heat changes spontaneously occurring during the reaction. The general features of this method to determine the kinetic and thermodynamic parameters of enzymatic reactions (kcat, KM, ΔH) are described and discussed here together with some detailed applications to specific cases. ITC does not require any modification or labeling of the system under analysis, can be performed in solution, and needs only small amounts of enzyme. These properties make ITC an invaluable, powerful, and unique tool to extend the knowledge of enzyme kinetics to drug discovery. © 2016 Elsevier Inc. All rights reserved.

  17. Isothermal Titration Calorimetry of Chiral Polymeric Nanoparticles.

    Science.gov (United States)

    Werber, Liora; Preiss, Laura C; Landfester, Katharina; Muñoz-Espí, Rafael; Mastai, Yitzhak

    2015-09-01

    Chiral polymeric nanoparticles are of prime importance, mainly due to their enantioselective potential, for many applications such as catalysis and chiral separation in chromatography. In this article we report on the preparation of chiral polymeric nanoparticles by miniemulsion polymerization. In addition, we describe the use of isothermal titration calorimetry (ITC) to measure the chiral interactions and the energetics of the adsorption of enantiomers from aqueous solutions onto chiral polymeric nanoparticles. The characterization of chirality in nano-systems is a very challenging task; here, we demonstrate that ITC can be used to accurately determine the thermodynamic parameters associated with the chiral interactions of nanoparticles. The use of ITC to measure the energetics of chiral interactions and recognition at the surfaces of chiral nanoparticles can be applied to other nanoscale chiral systems and can provide further insight into the chiral discrimination processes of nanomaterials. © 2015 Wiley Periodicals, Inc.

  18. Calorimetry for Fast Authentication of Edible Oils

    Science.gov (United States)

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

    2009-06-01

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

  19. Synergies between electromagnetic calorimetry and PET

    Energy Technology Data Exchange (ETDEWEB)

    Moses, William W.

    2002-07-30

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

  20. Titration Calorimetry Standards and the Precision of Isothermal Titration Calorimetry Data

    Science.gov (United States)

    Baranauskienė, Lina; Petrikaitė, Vilma; Matulienė, Jurgita; Matulis, Daumantas

    2009-01-01

    Current Isothermal Titration Calorimetry (ITC) data in the literature have relatively high errors in the measured enthalpies of protein-ligand binding reactions. There is a need for universal validation standards for titration calorimeters. Several inorganic salt co-precipitation and buffer protonation reactions have been suggested as possible enthalpy standards. The performances of several commercial calorimeters, including the VP-ITC, ITC200, and Nano ITC-III, were validated using these suggested standard reactions. PMID:19582227

  1. Modern Analysis of Protein Folding by Differential Scanning Calorimetry.

    Science.gov (United States)

    Ibarra-Molero, Beatriz; Naganathan, Athi N; Sanchez-Ruiz, Jose M; Muñoz, Victor

    2016-01-01

    Differential scanning calorimetry (DSC) is a very powerful tool for investigating protein folding and stability because its experimental output reflects the energetics of all conformations that become minimally populated during thermal unfolding. Accordingly, analysis of DSC experiments with simple thermodynamic models has been key for developing our understanding of protein stability during the past five decades. The discovery of ultrafast folding proteins, which have naturally broad conformational ensembles and minimally cooperative unfolding, opens the possibility of probing the complete folding free energy landscape, including those conformations at the top of the barrier to folding, via DSC. Exploiting this opportunity requires high-quality experiments and the implementation of novel analytical methods based on statistical mechanics. Here, we cover the recent exciting developments in this front, describing the new analytical procedures in detail as well as providing experimental guidelines for performing such analysis.

  2. ANALYSIS OF A HEAT-FLUX DIFFERENTIAL SCANNING CALORIMETRY INSTRUMENTS

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-01-01

    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.

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

    Science.gov (United States)

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

    2010-01-01

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

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

    Science.gov (United States)

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

    2010-12-01

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

  5. Current status of tritium calorimetry at TLK

    Energy Technology Data Exchange (ETDEWEB)

    Buekki-Deme, A.; Alecu, C.G.; Kloppe, B.; Bornschein, B. [Institute of Technical Physics, Tritium Laboratory Karsruhe - TLK, Karlsruhe Institute of Technology - KIT, Karlsruhe (Germany)

    2015-03-15

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

  6. Thermodynamic investigations of protein's behaviour with ionic liquids in aqueous medium studied by isothermal titration calorimetry.

    Science.gov (United States)

    Bharmoria, Pankaj; Kumar, Arvind

    2016-05-01

    While a number of reports appear on ionic liquids-proteins interactions, their thermodynamic behaviour using suitable technique like isothermal titration calorimetry is not systematically presented. Isothermal titration calorimetry (ITC) is a key technique which can directly measure the thermodynamic contribution of IL binding to protein, particularly the enthalpy, heat capacities and binding stoichiometry. Ionic liquids (ILs), owing to their unique and tunable physicochemical properties have been the central area of scientific research besides graphene in the last decade, and growing unabated. Their encounter with proteins in the biological system is inevitable considering their environmental discharge though most of them are recyclable for a number of cycles. In this article we will cover the thermodynamics of proteins upon interaction with ILs as osmolyte and surfactant. The up to date literature survey of IL-protein interactions using isothermal titration calorimetry will be discussed and parallel comparison with the results obtained for such studies with other techniques will be highlighted to demonstrate the accuracy of ITC technique. Net stability of proteins can be obtained from the difference in the free energy (ΔG) of the native (folded) and denatured (unfolded) state using the Gibbs-Helmholtz equation (ΔG=ΔH-TΔS). Isothermal titration calorimetry can directly measure the heat changes upon IL-protein interactions. Calculation of other thermodynamic parameters such as entropy, binding constant and free energy depends upon the proper fitting of the binding isotherms using various fitting models. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Determination of Purity by Differential Scanning Calorimetry (DSC).

    Science.gov (United States)

    Brown, M. E.

    1979-01-01

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

  8. Determination of Purity by Differential Scanning Calorimetry (DSC).

    Science.gov (United States)

    Brown, M. E.

    1979-01-01

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

  9. Effects of experimental variables in quantitative differential scanning calorimetry

    NARCIS (Netherlands)

    Dooren, Adrianus August van

    1982-01-01

    Dit proefschriÍt beschrijft een onderzoek naar de effecten van experimentele omstandigheden op curve-karakteristieken en enige toepassingen van kwantitatieve Differentiele Scanning calorimetry (DSC). ... Zie: Samenvatting

  10. Continuing Studies on Lead/Scintillating Fibres Calorimetry (LFC)

    CERN Multimedia

    2002-01-01

    Starting from the results obtained in the framework of the LAA Project~2B, we propose a continuation of the R&D on lead/scintillating fibres calorimetry (``spaghetti calorimetry''), including further tests on the old calorimeter prototypes and the construction and testing of new prototypes. The main results we pursue concern the performances of a projective calorimeter built with new, cheaper, techniques and the radiation hardness of the scintillating fibres, the optimization of a preshower detector system is also studied.

  11. Chemical kinetics on thermal decompositions of cumene hydroperoxide in cumene studied by calorimetry: An overview

    Energy Technology Data Exchange (ETDEWEB)

    Duh, Yih-Shing, E-mail: yihshingduh@yahoo.com.tw [Department of Occupation Safety and Health, Jen-Teh Junior College of Medicine, Nursing and Management, Miaoli, 35664, Taiwan, ROC (China); Department of Safety, Health and Environmental Engineering, National United University, No. 1 Lien-Da, Miaoli, 36052, Taiwan, ROC (China)

    2016-08-10

    Highlights: • Chemical kinetics on thermal decompositions of CHP are conducted and summarized. • Kinetics agrees well between data from DSC and adiabatic calorimetry. • Ea is determined to be about 120 kJ mol{sup −1} by various calorimetry. • LogA (A in s{sup −1}) is determined to be about 11.8 by various calorimetry. - Abstract: Study on chemical kinetics related to the thermal decomposition of cumene hydoperoxide (CHP) in cumene is summarized in this work. It is of great importance to gather and compare the differences between these kinetic parameters for further substantial applications in the chemical industry and process safety. CHP has been verified to possess an autocatalytic behavior by using microcalorimetry (such as TAM and C-80) operated at isothermal mode in the temperature range from 70 °C to 120 °C. However, it exhibits a reaction of n-th order detected by non-isothermal DSC scanning and adiabatic calorimeter. By the isothermal aging tests, activation energy and frequency factor in logA(s{sup −1}) were averaged to be (117.3 ± 5.9) kJ mol{sup −1}and (11.4 ± 0.3), respectively. Kinetic parameters acquired from data of interlaboratories by using heat-flow calorimetry, the averaged activation energy and frequency factor in logA(s{sup −1}) were (119.3 ± 11.3) kJ mol{sup −1}and (12.0 ± 0.2), respectively. On the analogy of results from adiabatic calorimetry, the activation energy and frequency factor in logA(s{sup −1}) were respectively averaged to be (122.4 ± 9.2) kJ mol{sup −1}and (11.8 ± 0.8). Five sets of kinetic models in relation to autocatalytic reactions are collected and discussed as well.

  12. Front-End Electronics in calorimetry: from LHC to ILC

    Energy Technology Data Exchange (ETDEWEB)

    De La Taille, Ch.

    2009-09-15

    This report summarizes the electronics developments for liquid argon calorimeter read-out at LHC and the development carried out in the framework of the CALICE collaboration for those of the future linear collider (ILC). It also includes chips designed for multi-anode photomultipliers (MaPMT) used in the OPERA experiment or on ATLAS luminometer, which also find applications in medical imaging. Started in the early 90's, the development for ATLAS calorimetry was extremely challenging in terms of readout speed, radiation tolerance and measurement accuracy. The high speed has required a new approach using current-sensitive preamplifiers instead of charge sensitive ones and the redefinition of noise performance in terms of ENI. The preamplifiers developed at Orsay and the monolithic shapers are described in Chapter 1, including considerations of digital filtering, which was a new technique in our field. Chapter 2 is dedicated to the calibration system, designed and built by Orsay, for which the high performance and accuracy necessitated in-depth studies. The 3. chapter closes the studies for ATLAS with a summary of the detector measurements which had to be carried out on the 200 000 channels in order to understand and model the detector and achieve everywhere the accuracy and uniformity at per-cent level. These developments for ATLAS ended in 2004, although parallel work was also carried out for the NA48 and DO calorimeters which are not detailed here. The next generation of collider will require a new generation of calorimeters, much more granular, referred to as 'imaging calorimetry' with embedded read-out electronics. The ASICs developed for this purpose in the framework of the CALICE collaboration are described in Chapter 4. They integrate all the functionalities of amplification, digitization and read-out making them complex 'System-On-Chip' circuits extremely efficient that find many other applications. A family of 3 chips reads out the

  13. Influence of frost damage and sample preconditioning on the porosity characterization of cement based materials using low temperature calorimetry

    DEFF Research Database (Denmark)

    Wu, Min; Fridh, Katja; Johannesson, Björn

    2015-01-01

    Low temperature calorimetry (LTC) can be used to study the meso-porosity of cement based materials. The influence of frost damage on the meso-porosity determination by LTC was explored on a model material MCM-41 and two cement pastes by conducting repeated cycles of freezing and melting measureme......Low temperature calorimetry (LTC) can be used to study the meso-porosity of cement based materials. The influence of frost damage on the meso-porosity determination by LTC was explored on a model material MCM-41 and two cement pastes by conducting repeated cycles of freezing and melting...

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

    Science.gov (United States)

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

    2016-01-01

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

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

    Science.gov (United States)

    O'Neill, Michael A A; Gaisford, Simon

    2011-09-30

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

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

    Science.gov (United States)

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

    2011-09-18

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

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

    Science.gov (United States)

    Royall, P G; Gaisford, S

    2005-06-01

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

  18. Interaction of diethyl aniline methylphosphonate with DNA: Spectroscopic and isothermal titration calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Lu Yan, E-mail: yanlu2001@sohu.co [College of Chemistry and Environmental Science, Henan Normal University, Xinxiang, Henan 453007 (China); Xu Meihua; Wang Gongke; Zheng Yun [College of Chemistry and Environmental Science, Henan Normal University, Xinxiang, Henan 453007 (China)

    2011-05-15

    In this study the diethyl aniline methylphosphonate (DAM) was synthesized, the interaction of DAM with ct-DNA has been investigated by fluorescence spectra, UV spectra, molecular modeling and isothermal titration calorimetry (ITC). The binding constant of DAM to ct-DNA calculated from both isothermal titration calorimetry and fluorescence spectra were found to be in the 10{sup 4} M{sup -1} range. According to the ethidium bromide displacement studies, UV spectra and isothermal titration calorimetry experimental results, it can be concluded that DAM is an intercalator that can slide into the G-C rich region of ct-DNA. Furthermore, the results obtained from molecular modeling corroborated the experimental results obtanied from spectroscopic and ITC investigations. At the same time, fluorescence spectra suggested that the mechanism of the interaction of DAM to ct-DNA was a static enhancing type. ITC data showed that ct-DNA/DAM binding is enthalpy controlled. - Research highlights: The interaction of DAM with ct-DNA is a static enhancing type. DAM can slide into the G-C rich region of ct-DNA. The binding of DAM to ct-DNA is enthalpy controlled. The hydrogen bonding forces play an essential role in the binding process.

  19. Liquid Argon Calorimetry with LHC-Performance Specifications

    CERN Multimedia

    2002-01-01

    % RD-3 Liquid Argon Calorimetry with LHC-Performance Specifications \\\\ \\\\Good electromagnetic and hadronic calorimetry will play a central role in an LHC detector. Among the techniques used so far, or under development, the liquid argon sampling calorimetry offers high radiation resistence, good energy resolution (electromagnetic and hadronic), excellent calibration stability and response uniformity. Its rate capabilities, however, do not yet match the requirements for LHC. \\\\ \\\\The aim of this proposal is to improve the technique in such a way that high granularity, good hermiticity and adequate rate capabilities are obtained, without compromising the above mentioned properties. To reach this goal, we propose to use a novel structure, the $^{\\prime\\prime}$accordion$^{\\prime\\prime}$, coupled to fast preamplifiers working at liquid argon temperature. Converter and readout electrodes are no longer planar and perpendicular to particles, as usual, but instead they are wiggled around a plane containing particles. ...

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

    Science.gov (United States)

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

    2017-01-01

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

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

    Science.gov (United States)

    Kim, Eun Ran; Tong, Qingchun

    2017-01-01

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

  2. Differential scanning calorimetry to quantify the stability of protein cages.

    Science.gov (United States)

    Zhang, Yu; Ardejani, Maziar S

    2015-01-01

    Differential scanning calorimetry (DSC) is an experimental technique through which the differences in amount of heat required to maintain equal temperature between a sample and a reference cell are measured at various temperatures. The quantified heat relates to the differences in apparent heat capacity of the analytes. The data from DSC studies will thereby provide direct information about the energetics of thermally induced processes in the sample. Here we present a detailed protocol to quantify the thermostability of protein cage, bacterioferritin (BFR), using differential scanning calorimetry.

  3. Indirect calorimetry: assessing animal response to heat and cold stress

    NARCIS (Netherlands)

    Gaughan, J.B.; Heetkamp, M.J.W.; Hendriks, P.

    2015-01-01

    Calorimetric thermal stress studies where indirect calorimetry is used as a tool to estimate energy expenditure have been undertaken since this technique was developed. Some examples of these studies are presented in this chapter. The measurement of gas exchange by means of an open-circuit

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

    Science.gov (United States)

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

    2016-08-01

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

  5. Isothermal Titration Calorimetry Can Provide Critical Thinking Opportunities

    Science.gov (United States)

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

    2016-01-01

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

  6. Novel investigation of enzymatic biodiesel reaction by isothermal calorimetry

    DEFF Research Database (Denmark)

    Søtoft, Lene Fjerbaek; Westh, Peter; Christensen, Knud V.

    2010-01-01

    Isothermal calorimetry (ITC) was used to investigate solvent-free enzymatic biodiesel production. The transesterification of rapeseed oil with methanol and ethanol was catalyzed by immobilized lipase Novozym 435 at 40 °C. The aim of the study was to determine reaction enthalpy for the enzymatic...

  7. Isothermal Titration Calorimetry Can Provide Critical Thinking Opportunities

    Science.gov (United States)

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

    2016-01-01

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

  8. Differential scanning calorimetry on mixtures of lecithin, lysolecithin and cholesterol

    NARCIS (Netherlands)

    Klopfenstein, W.E.; Kruyff, B. de; Verkleij, A.J.; Demel, R.A.; Deenen, L.L.M. van

    1974-01-01

    The effect of increasing concentrations of lysolecithin (1-palmitoyl-sn-glycerol-3-phosphorylcholine) on the gel → liquid crystal thermal transition of lecithin (1,2-dipalmitoyl-sn-glycerol-3-phosphorylcholine) in the aqueous phase was studied by differential scanning calorimetry (DSC). Lysolecithin

  9. Preparation of Solid Derivatives by Differential Scanning Calorimetry.

    Science.gov (United States)

    Crandall, E. W.; Pennington, Maxine

    1980-01-01

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

  10. Preparation of Solid Derivatives by Differential Scanning Calorimetry.

    Science.gov (United States)

    Crandall, E. W.; Pennington, Maxine

    1980-01-01

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

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

    Science.gov (United States)

    Maskow, Thomas; Paufler, Sven

    2015-04-01

    This article presents and compares several thermodynamic methods for the quantitative interpretation of data from calorimetric measurements. Heat generation and absorption are universal features of microbial growth and product formation as well as of cell cultures from animals, plants and insects. The heat production rate reflects metabolic changes in real time and is measurable on-line. The detection limit of commercially available calorimetric instruments can be low enough to measure the heat of 100,000 aerobically growing bacteria or of 100 myocardial cells. Heat can be monitored in reaction vessels ranging from a few nanoliters up to many cubic meters. Most important the heat flux measurement does not interfere with the biological process under investigation. The practical advantages of calorimetry include the waiver of labeling and reactants. It is further possible to assemble the thermal transducer in a protected way that reduces aging and thereby signal drifts. Calorimetry works with optically opaque solutions. All of these advantages make calorimetry an interesting method for many applications in medicine, environmental sciences, ecology, biochemistry and biotechnology, just to mention a few. However, in many cases the heat signal is merely used to monitor biological processes but only rarely to quantitatively interpret the data. Therefore, a significant proportion of the information potential of calorimetry remains unutilized. To fill this information gap and to motivate the reader using the full information potential of calorimetry, various methods for quantitative data interpretations are presented, evaluated and compared with each other. Possible errors of interpretation and limitations of quantitative data analysis are also discussed. Copyright © 2014 Elsevier Inc. All rights reserved.

  12. Titration Calorimetry Applied to the Thermokinetics Study of Consecutive First-order Reactions

    Institute of Scientific and Technical Information of China (English)

    SHI Jing-Yan; LI Jie; WANG Zhi-Yong; LIU Yu-Wen; WANG Cun-Xin

    2008-01-01

    The thermokinetic mathematical models for consecutive first-order reactions in titration period and the stopped-titration reaction period were proposed for titration calorimetry, based on which, thermodynamic parameters (reaction enthalpies, △rHm1 and △rHm2) and kinetic parameters (rate constants, k1 and k2) of the consecutive first-order reactions could be obtained by directly simulating the calorimetric curve from a single experiment with the method of nonlinear least squares regression (NLLS).The reliability of the model has been verified by investigating the reaction of the saponification of diethyl succinate in an aqueous ethanol solvent.

  13. ATLAS calorimetry. Trigger, simulation and jet calibration

    Energy Technology Data Exchange (ETDEWEB)

    Weber, P.

    2007-02-06

    The Pre-Processor system of the ATLAS Level-1 Calorimeter Trigger performs complex processing of analog trigger tower signals from electromagnetic and hadronic calorimeters. The main processing block of the Pre-Processor System is the Multi-Chip Module (MCM). The first part of this thesis describes MCM quality assurance tests that have been developed, their use in the MCM large scale production and the results that have been obtained. In the second part of the thesis a validation of a shower parametrisation model for the ATLAS fast simulation package ATLFAST based on QCD dijet events is performed. A detailed comparison of jet response and jet energy resolution between the fast and the full simulation is presented. The uniformity of the calorimeter response has a significant impact on the accuracy of the jet energy measurement. A study of the calorimeter intercalibration using QCD dijet events is presented in the last part of the thesis. The intercalibration study is performed in azimuth angle {phi} and in pseudorapidity {eta}. The performance of the calibration methods including possible systematic and statistical effects is described. (orig.)

  14. ATLAS calorimetry: Trigger, simulation and jet calibration

    CERN Document Server

    Weber, Pavel

    2008-01-01

    The Pre-Processor system of the ATLAS Level-1 Calorimeter Trigger performs complex processing of analog trigger tower signals from electromagnetic and hadronic calorimeters. The main processing block of the Pre-Processor System is the Multi-Chip Module (MCM). The first part of this thesis describes MCM quality assurance tests that have been developed, their use in the MCM large scale production and the results that have been obtained. In the second part of the thesis a validation of a shower parametrisation model for the ATLAS fast simulation package ATLFAST based on QCD dijet events is performed. A detailed comparison of jet response and jet energy resolution between the fast and the full simulation is presented. The uniformity of the calorimeter response has a significant impact on the accuracy of the jet energy measurement. A study of the calorimeter intercalibration using QCD dijet events is presented in the last part of the thesis. The intercalibration study is performed in azimuth angle phi and in pseud...

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

    Science.gov (United States)

    2015-08-01

    Calorimetry by Matthew S Tenan Approved for public release; distribution is unlimited. NOTICES Disclaimers...Simulation to Understand Measurement Error in Indirect Calorimetry by Matthew S Tenan Human Research and Engineering Directorate, ARL...VO2sim 0.1: Using Simulation to Understand Measurement Error in Indirect Calorimetry 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT

  16. Procedure Development to Determine the Heat of Combustion of an Energetic Liquid by Bomb Calorimetry

    Science.gov (United States)

    2015-01-01

    ENERGETIC LIQUID BY BOMB CALORIMETRY Peggy Sanchez Kimberly Griswold January 2015 Approved for public...2014 4. TITLE AND SUBTITLE PROCEDURE DEVELOPMENT TO DETERMINE THE HEAT OF COMBUSTION OF AN ENERGETIC LIQUID BY BOMB CALORIMETRY 5a. CONTRACT...experimentally determining the heat of formation of a liquid by bomb calorimetry can be challenging. Running the liquid pooled in the sample well leads to

  17. Calorimetry applied to nucleus-nucleus collisions at ultrarelativistic energies

    Energy Technology Data Exchange (ETDEWEB)

    Plasil, F.

    1988-01-01

    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.

  18. Monitoring assembly of ribonucleoprotein complexes by isothermal titration calorimetry

    OpenAIRE

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

    2008-01-01

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

  19. Accurate Measurement of Heat Capacity by Differential Scanning Calorimetry

    Science.gov (United States)

    1984-01-01

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

  20. Accurate Measurement of Heat Capacity by Differential Scanning Calorimetry

    Science.gov (United States)

    1984-01-01

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

  1. Differential Scanning Calorimetry of Superelastic Nitinol for Tuneable Devices

    OpenAIRE

    Feeney, Andrew; LUCAS, MARGARET

    2015-01-01

    Nitinol has been used to fabricate tuneable-frequency cymbal transducers by exploiting its solid-state phase transformation capability. The temperatures at which Nitinol transforms\\ud are commonly measured using differential scanning calorimetry (DSC). However, these\\ud measurements are shown to be inaccurate for superelastic Nitinol, reportedly attributed to residual stresses in the material resulting from the fabrication process. This study of DSC accuracy is conducted for untreated and hea...

  2. Laser-Shock Experiments: Calorimetry Measurements to TPa Pressures

    Science.gov (United States)

    Jeanloz, R.

    2012-12-01

    Laser-driven shock experiments are more like calorimetry measurements, characterized by determinations of Hugoniot temperature (TH) as a function of shock velocity (US), rather than the equation-of-state measurements afforded by mechanical-impact experiments. This is because particle velocity (up) is often not accessible to direct measurement in laser-shock experiments, so must be inferred with reference to a material having a well-determined, independently calibrated Hugoniot equation of state (up is obtained from the impact velocity in traditional shock experiments, and the combination of US and up yields the pressure-density equation of state for the sample). Application of a Mie-Grüneisen model shows that the isochoric specific heat for a given phase is: CV = (US - c0)2 {s2US (dTH/dUS) + γ0 c0 s (TH/US)}-1 with US = c0 + s up, and γ0 is the zero-pressure Grüneisen parameter (γ/V = constant is assumed here). This result is a generalization to TH-US variables of the Walsh and Christian (1955) formula for the temperature rise along the Hugoniot of a given phase (identified here with a US - up relation that is locally linear); it can be analytically integrated to give TH(US) in terms of an average value of CV, if no phase transition takes place. Analysis of the TH-US slopes obtained from laser-shock measurements on MgO yields specific-heat values ranging from 1.02 (± 0.05) kJ/kg/K at 320-345 GPa and TH = 7700-9000 K to 1.50 (± 0.05) kJ/kg/K at 350-380 GPa and TH = 8700-9500 K. A fit to the absolute values of TH(US) in this pressure-temperature range gives CV = 1.26 (± 0.10) kJ/kg/K, in good accord with the Dulong-Petit value CV = 1.24 kJ/kg/K.

  3. Investigation of binary solid phases by calorimetry and kinetic modelling

    NARCIS (Netherlands)

    Matovic, M.

    2007-01-01

    The traditional methods for the determination of liquid-solid phase diagrams are based on the assumption that the overall equilibrium is established between the phases. However, the result of the crystallization of a liquid mixture will typically be a non-equilibrium or metastable state of the solid

  4. Amphiphilic naproxen prodrugs: differential scanning calorimetry study on their interaction with phospholipid bilayers.

    Science.gov (United States)

    Giuffrida, Maria Chiara; Pignatello, Rosario; Castelli, Francesco; Sarpietro, Maria Grazia

    2017-09-01

    Naproxen, a nonsteroid anti-inflammatory drug studied for Alzheimer's disease, was conjugated with lipoamino acids (LAA) directly or through a diethylamine (EDA) spacer to improve the drug lipophilicity and the interaction with phospholipid bilayers. The interaction of naproxen and its prodrugs with biomembrane models consisting of dimyristoylphosphatidylcholine multilamellar vesicles was studied by differential scanning calorimetry. The transfer of prodrugs from a lipophilic carrier to a biomembrane model was also studied. Naproxen conjugation to lipoamino acids improves its interaction with biomembrane models and affects the transfer from a lipophilic carrier to biomembrane model. LAA portion may localize between the phospholipid chains; the entity of the interaction depends not only on the presence of the spacer but also on the LAA chain length. Variation of LAA portion can modulate the naproxen prodrugs affinity towards the biological membrane as well as towards the lipophilic carrier. © 2017 Royal Pharmaceutical Society.

  5. What can we get from varying scan rate in protein differential scanning calorimetry?

    Science.gov (United States)

    Amani, Mojtaba; Moosavi-Movahedi, Ali A; Kurganov, Boris I

    2017-06-01

    Differential scanning calorimetry has many advantages over other techniques to study the thermal stability of proteins due to its direct measurement of thermodynamic parameters. Most proteins undergo irreversible thermal denaturation causing their thermogram to be scan rate dependent. We modeled reversible and irreversible protein thermograms at varying scan rates. The complete Lumry-Eyring model was used to model the irreversible thermograms at various values of T1/2 (temperature at which equilibrium constant equals unity) and T* (temperature at which rate constant equals 1min(-1)). Our results have shown that the thermal effects of two processes are integrated with decreasing the T* relative to T1/2. It is also shown that the shape of second derivatives of thermograms under different conditions have specific pattern which can be used to judge and estimate the correct model for protein denaturation. Copyright © 2017 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

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

    2008-12-15

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

  7. Simultaneous Thermodynamic and Kinetic Parameters Determination Using Differential Scanning Calorimetry

    Directory of Open Access Journals (Sweden)

    Nader Frikha

    2011-01-01

    Full Text Available Problem statement: The determination of reaction kinetics is of major importance, as for industrial reactors optimization as for environmental reasons or energy limitations. Although calorimetry is often used for the determination of thermodynamic parameters alone, the question that arises is: how can we apply the Differential Scanning Calorimetry for the determination of kinetic parameters. The objective of this study consists to proposing an original methodology for the simultaneous determination of thermodynamic and kinetic parameters, using a laboratory scale Differential Scanning Calorimeter (DSC. The method is applied to the dichromate-catalysed hydrogen peroxide decomposition. Approach: The methodology is based on operating of experiments carried out with a Differential Scanning Calorimeter. The interest of this approach proposed is that it requires very small quantities of reactants (about a few grams to be implemented. The difficulty lies in the fact that, using such microcalorimeters, the reactants temperature cannot directly be measured and a particular calibration procedure has thus to be developed, to determine the media temperature in an indirect way. The proposed methodology for determination of kinetics parameters is based on resolution of the coupled heat and mass balances. Results: A complete kinetic law is proposed. The Arrhenius parameters are determined as frequency factor k0 = 1.39×109 s−1 and activation energy E = 54.9 kJ mol−1. The measured enthalpy of reaction is ΔrH=−94 kJ mol−1. Conclusion: The comparison of the results obtained by such an original methodology with those obtained using a conventional laboratory scale reactor calorimetry, for the kinetics determination of, shows that this new approach is very relevant.

  8. Measuring thermal conductivity of powders with differential scanning calorimetry

    OpenAIRE

    Pujula, Miquel; Sánchez-Rodríguez, Daniel; López-Olmedo, Joan Pere; Farjas Silva, Jordi; Roura Grabulosa, Pere

    2016-01-01

    This paper simplifies a recently proposed method for measuring the thermal conductivity of powders using differential scanning calorimetry (DSC) (Sa´nchez-Rodríguez et al. in J Therm Anal Calorim 121:469-473, 2015). With this method, a crucible is filled with powder and a spherical metal reference is partially sunk into it. The thermal resistance between the metal and the crucible wall at the metal melting point is obtained from the DSC melting peak slope. In the simplified method outlined in...

  9. Shashlik calorimetry a combined Shashlik + Preshower detector for LHC

    CERN Document Server

    Badier, J; Busata, A; CERN. Geneva. Detector Research and Development Committee

    1993-01-01

    Shashlik Calorimetry is a new technique which has been developed to read out the light from lead/scintillator sampling calorimeters, using wavelength shifters and optical fibres. The light yield is in excess of 10000 photons per GeV with fine lateral segmentation and minimum dead space. It is expected that such calorimeters can be buildt at relatively low cost. The first results on energy resolution and angular resolution, obtained in a non-projective prototype exposed to high energy electrons, are encouraging. Further research and development are essential before building a full scale projective detector.

  10. Monitoring assembly of ribonucleoprotein complexes by isothermal titration calorimetry

    Science.gov (United States)

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

    2010-01-01

    Isothermal titration calorimetry (ITC) is a useful technique to study RNA-protein interactions, as it provides the only method by which the thermodynamic parameters of free energy, enthalpy, and entropy can be directly determined. This chapter presents a general procedure for studying RNA-protein interactions using ITC, and gives specific examples for monitoring the binding of Caenorhabditis elegans GLD-1 STAR domain to TGE RNA and the binding of Aquifex aeolicus S6:S18 ribosomal protein heterodimer to an S15-rRNA complex. PMID:18982287

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

    Science.gov (United States)

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

    2016-01-01

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

  12. Isothermal Titration Calorimetry of Membrane Proteins – Progress and Challenges

    Science.gov (United States)

    Rajarathnam, Krishna; Rösgen, Jörg

    2013-01-01

    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

  13. Fast differential scanning calorimetry of liquid samples with chips

    DEFF Research Database (Denmark)

    Splinter, R.; van Herwaarden, A. W.; van Wetten, I. A.

    2015-01-01

    Based on a modified version of standard chips for fast differential scanning calorimetry, DSC of liquid samples has been performed at temperature scan rates of up to 1000 °C/s. This paper describes experimental results with the protein lysozyme, bovine serum, and olive oil. The heating and cooling....... The bovine serum measurements show two main peaks, in good agreement with standard DSC measurements. Olive oil has been measured, with good agreement for the cooling curve and qualitative agreement for the heater curve, compared to DSC measurements....

  14. Heat of supersaturation-limited amyloid burst directly monitored by isothermal titration calorimetry

    Science.gov (United States)

    Ikenoue, Tatsuya; Lee, Young-Ho; Kardos, József; Yagi, Hisashi; Ikegami, Takahisa; Naiki, Hironobu; Goto, Yuji

    2014-01-01

    Amyloid fibrils form in supersaturated solutions via a nucleation and growth mechanism. Although the structural features of amyloid fibrils have become increasingly clearer, knowledge on the thermodynamics of fibrillation is limited. Furthermore, protein aggregation is not a target of calorimetry, one of the most powerful approaches used to study proteins. Here, with β2-microglobulin, a protein responsible for dialysis-related amyloidosis, we show direct heat measurements of the formation of amyloid fibrils using isothermal titration calorimetry (ITC). The spontaneous fibrillation after a lag phase was accompanied by exothermic heat. The thermodynamic parameters of fibrillation obtained under various protein concentrations and temperatures were consistent with the main-chain dominated structural model of fibrils, in which overall packing was less than that of the native structures. We also characterized the thermodynamics of amorphous aggregation, enabling the comparison of protein folding, amyloid fibrillation, and amorphous aggregation. These results indicate that ITC will become a promising approach for clarifying comprehensively the thermodynamics of protein folding and misfolding. PMID:24753579

  15. Application of an open circuit indirect calorimetry system for gaseous exchange measurements in small ruminant nutrition

    OpenAIRE

    CRISCIONI FERREIRA, PATRICIA FABIOLA

    2016-01-01

    [EN] The main objective of this Thesis was to study the energy metabolism in small ruminants under different nutrition sceneries. As methodology we utilized indirect calorimetry instead of direct calorimetry or feeding trials. Within indirect calorimetry we worked with a portable open circuit gas exchange system with a head hood. This open circuit respiration system permitted completed the whole energy balance and evaluate the efficiency of utilization of the energy of the diet for different ...

  16. Advanced ion beam calorimetry for the test facility ELISE

    Science.gov (United States)

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

    2015-04-01

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

  17. Overview on differential scanning calorimetry applications for early stage of cancers: brief report

    National Research Council Canada - National Science Library

    Hoda Keshmiri-Neghab; Bahram Goliaei; Ali Akbar Saboury; Ali Akbar Moosavi-Movahedi

    2016-01-01

    .... While some researchers have dismissed the low molecular weight serum peptidome as biological trash, recent work using differential scanning calorimetry has indicated that the peptidome may reflect...

  18. Do PICU patients meet technical criteria for performing indirect calorimetry?

    Science.gov (United States)

    Beggs, Megan R; Garcia Guerra, Gonzalo; Larsen, Bodil M K

    2016-10-01

    Indirect calorimetry (IC) is considered gold standard for assessing energy needs of critically ill children as predictive equations and clinical status indicators are often unreliable. Accurate assessment of energy requirements in this vulnerable population is essential given the high risk of over or underfeeding and the consequences thereof. The proportion of patients and patient days in pediatric intensive care (PICU) for which energy expenditure (EE) can be measured using IC is currently unknown. In the current study, we aimed to quantify the daily proportion of consecutive PICU patients who met technical criteria to perform indirect calorimetry and describe the technical contraindications when criteria were not met. Prospective, observational, single-centre study conducted in a cardiac and general PICU. All consecutive patients admitted for at least 96 h were included in the study. Variables collected for each patient included age at admission, admission diagnosis, and if technical criteria for indirect calorimetry were met. Technical criteria variables were collected within the same 2 h each morning and include: provision of supplemental oxygen, ventilator settings, endotracheal tube (ETT) leak, diagnosis of chest tube air leak, provision of external gas support (i.e. nitric oxide), and provision of extracorporeal membrane oxygenation (ECMO). 288 patients were included for a total of 3590 patient days between June 2014 and February 2015. The main reasons for admission were: surgery (cardiac and non-cardiac), respiratory distress, trauma, oncology and medicine/other. The median (interquartile range) patient age was 0.7 (0.3-4.6) years. The median length of PICU stay was 7 (5-14) days. Only 34% (95% CI, 32.4-35.5%) of patient days met technical criteria for IC. For patients less than 6 months of age, technical criteria were met on significantly fewer patient days (29%, p technical criteria for IC on any day during their PICU stay. Most frequent reasons for

  19. Applications of isothermal titration calorimetry in protein science.

    Science.gov (United States)

    Liang, Yi

    2008-07-01

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

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

    Science.gov (United States)

    Gilbert, Sunny D; Batey, Robert T

    2009-01-01

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

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

    Science.gov (United States)

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

    2016-01-01

    Isothermal titration calorimetry (ITC) provides a sensitive and accurate means by which to study the thermodynamics of binding reactions. In addition, it enables label-free measurement of enzymatic reactions. The advent of extremely sensitive microcalorimeters have made it increasingly valuable as a tool for hit validation and characterization, but its use in primary screening is hampered by requiring large quantities of reagents and long measurement times. Nanocalorimeters can overcome these limitations of conventional ITC, particularly for screening libraries of 500-1000 compounds such as those encountered in fragment-based lead discovery. This chapter describes how nanocalorimetry and conventional microcalorimetry can be used to screen compound libraries for enzyme inhibitors. © 2016 Elsevier Inc. All rights reserved.

  2. Isothermal Titration Calorimetry for Measuring Macromolecule-Ligand Affinity

    Science.gov (United States)

    Duff,, Michael R.; Grubbs, Jordan; Howell, Elizabeth E.

    2011-01-01

    Isothermal titration calorimetry (ITC) is a useful tool for understanding the complete thermodynamic picture of a binding reaction. In biological sciences, macromolecular interactions are essential in understanding the machinery of the cell. Experimental conditions, such as buffer and temperature, can be tailored to the particular binding system being studied. However, careful planning is needed since certain ligand and macromolecule concentration ranges are necessary to obtain useful data. Concentrations of the macromolecule and ligand need to be accurately determined for reliable results. Care also needs to be taken when preparing the samples as impurities can significantly affect the experiment. When ITC experiments, along with controls, are performed properly, useful binding information, such as the stoichiometry, affinity and enthalpy, are obtained. By running additional experiments under different buffer or temperature conditions, more detailed information can be obtained about the system. A protocol for the basic setup of an ITC experiment is given. PMID:21931288

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

    Science.gov (United States)

    Boudker, Olga; Oh, SeCheol

    2015-04-01

    Binding of ligands, ranging from proteins to ions, to membrane proteins is associated with absorption or release of heat that can be detected by isothermal titration calorimetry (ITC). Such measurements not only provide binding affinities but also afford direct access to thermodynamic parameters of binding--enthalpy, entropy and heat capacity. These parameters can be interpreted in a structural context, allow discrimination between different binding mechanisms and guide drug design. In this review, we introduce advantages and limitations of ITC as a methodology to study molecular interactions of membrane proteins. We further describe case studies where ITC was used to analyze thermodynamic linkage between ions and substrates in ion-coupled transporters. Similar type of linkage analysis will likely be applicable to a wide range of transporters, channels, and receptors. Copyright © 2015 Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

    Rajarathnam, Krishna; Rösgen, Jörg

    2014-01-01

    Integral membrane proteins, including G protein-coupled receptors (GPCR) and ion channels, mediate diverse biological functions that are crucial to all aspects of life. The knowledge of the molecular mechanisms, and in particular, the thermodynamic basis of the binding interactions of the extracellular ligands and intracellular effector proteins is essential to understand the workings of these remarkable nanomachines. In this review, we describe how isothermal titration calorimetry (ITC) can be effectively used to gain valuable insights into the thermodynamic signatures (enthalpy, entropy, affinity, and stoichiometry), which would be most useful for drug discovery studies, considering that more than 30% of the current drugs target membrane proteins. This article is part of a Special Issue entitled: Structural and biophysical characterisation of membrane protein-ligand binding. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Hadronic Shower Development in Iron-Scintillator Tile Calorimetry

    CERN Document Server

    Amaral, P; Anderson, K; Barreira, G; Benetta, R; Berglund, S; Biscarat, C; Blanchot, G; Blucher, E; Bogush, A A; Bohm, C; Boldea, V; Borisov, O; Bosman, M; Bromberg, C; Budagov, Yu A; Burdin, S; Caloba, L; Carvalho, J; Casado, M P; Castillo, M V; Cavalli-Sforza, M; Cavasinni, V; Chadelas, R; Chirikov-Zorin, I E; Chlachidze, G; Cobal, M; Cogswell, F; Colaço, F; Cologna, S; Constantinescu, S; Costanzo, D; Crouau, M; Daudon, F; David, J; David, M; Davidek, T; Dawson, J; De, K; Del Prete, T; De Santo, A; Di Girolamo, B; Dita, S; Dolejsi, J; Dolezal, Z; Downing, R; Efthymiopoulos, I; Engström, M; Errede, D; Errede, S; Evans, H; Fenyuk, A; Ferrer, A; Flaminio, V; Gallas, E; Gaspar, M; Gil, I; Gildemeister, O; Glagolev, V; Gomes, A; González, V; González de la Hoz, S; Grabskii, V; Graugès-Pous, E; Grenier, P; Hakopian, H H; Haney, M; Hansen, M; Hellman, S; Henriques, A; Hébrard, C; Higón, E; Holmgren, S O; Huston, J; Ivanyushenkov, Yu M; Jon-And, K; Juste, A; Kakurin, S; Karapetian, G V; Karyukhin, A N; Kopikov, S; Kukhtin, V; Kulchitskii, Yu A; Kurzbauer, W; Kuzmin, M; Lami, S; Lapin, V; Lazzeroni, C; Lebedev, A; Leitner, R; Li, J; Lomakin, Yu F; Lomakina, O V; Lokajícek, M; López-Amengual, J M; Maio, A; Malyukov, S; Marroquin, F; Martins, J P; Mazzoni, E; Merritt, F S; Miller, R; Minashvili, I A; Miralles, L; Montarou, G; Munar, A; Némécek, S; Nessi, Marzio; Onofre, A; Orteu, S; Park, I C; Pallin, D; Pantea, D; Paoletti, R; Patriarca, J; Pereira, A; Perlas, J A; Petit, P; Pilcher, J E; Pinhão, J; Poggioli, L; Price, L; Proudfoot, J; Pukhov, O; Reinmuth, G; Renzoni, G; Richards, R; Roda, C; Romance, J B; Romanov, V; Ronceux, B; Rosnet, P; Rumyantsev, V; Rusakovich, N; Sanchis, E; Sanders, H; Santoni, C; Santos, J; Sawyer, L; Says, L P; Seixas, J M; Selldén, B; Semenov, A; Shchelchkov, A S; Shochet, M; Simaitis, V; Sissakian, A N; Solodkov, A; Solovyanov, O; Sonderegger, P; Sosebee, M; Soustruznik, K; Spanó, F; Stanek, R; Starchenko, E A; Stephens, R; Suk, M; Tang, F; Tas, P; Thaler, J; Tokar, S; Topilin, N; Trka, Z; Turcot, A S; Turcotte, M; Valkár, S; Varandas, M J; Vartapetian, A H; Vazeille, F; Vichou, I; Vinogradov, V; Vorozhtsov, S B; Wagner, D; White, A; Wolters, H; Yamdagni, N; Yarygin, G; Yosef, C; Zaitsev, A; Zdrazil, M; Zúñiga, J

    2000-01-01

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

  6. Biophysical characterization of antibodies with isothermal titration calorimetry

    Directory of Open Access Journals (Sweden)

    Verna Frasca

    2016-07-01

    Full Text Available Antibodies play a key role in the immune response. Since antibodies bind antigens with high specificity and tight affinity, antibodies are an important reagent in experimental biology, assay development, biomedical research and diagnostics. Monoclonal antibodies are therapeutic drugs and used for vaccine development. Antibody engineering, biophysical characterization, and structural data have provided a deeper understanding of how antibodies function, and how to make better drugs. Isothermal titration calorimetry (ITC is a label-free binding assay, which measures affinity, stoichiometry, and binding thermodynamics for biomolecular interactions. When thermodynamic data are used together with structural and kinetic data from other assays, a complete structure-activity-thermodynamics profile can be constructed. This review article describes ITC, and discusses several applications on how data from ITC provides insights into how antibodies function, guide antibody engineering, and aid design of new therapeutic drugs.

  7. Applications of isothermal titration calorimetry in protein science

    Institute of Scientific and Technical Information of China (English)

    Yi Liang

    2008-01-01

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

  8. DETECTION OF Tg BY MODULATED DIFFERENTIAL SCANNING CALORIMETRY

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    The glassy transition of the polyethylene terephthalate (PET) samples which have been subjected to solvent induced crystallization (SINC) was investigated by modulated differential scanning calorimetry (MDSC) and density measurement. The differential of heat capacity signal, d Cp/dT from MDSC, was used to monitor the SINC process. It reveals that the Tg temperature shifts to higher value with the advancement of SINC. When the toluene-immersing time was longer (168h), the detection of Tg become more difficult, because some smaller peaks emerged at the lower temperatures and these are explained as the movement of small segments in the amorphous region. These observed results are due to the morphology and structure introduced by the SINC process.

  9. Review of MEMS differential scanning calorimetry for biomolecular study

    Science.gov (United States)

    Yu, Shifeng; Wang, Shuyu; Lu, Ming; Zuo, Lei

    2017-07-01

    Differential scanning calorimetry (DSC) is one of the few techniques that allow direct determination of enthalpy values for binding reactions and conformational transitions in biomolecules. It provides the thermodynamics information of the biomolecules which consists of Gibbs free energy, enthalpy and entropy in a straightforward manner that enables deep understanding of the structure function relationship in biomolecules such as the folding/unfolding of protein and DNA, and ligand bindings. This review provides an up to date overview of the applications of DSC in biomolecular study such as the bovine serum albumin denaturation study, the relationship between the melting point of lysozyme and the scanning rate. We also introduce the recent advances of the development of micro-electro-mechanic-system (MEMS) based DSCs.

  10. Hadronic shower development in Iron-Scintillator Tile Calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Amaral, P.; Amorim, A.; Anderson, K.; Barreira, G.; Benetta, R.; Berglund, S.; Biscarat, C.; Blanchot, G.; Blucher, E.; Bogush, A.; Bohm, C.; Boldea, V.; Borisov, O.; Bosman, M.; Bromberg, C.; Budagov, J.; Burdin, S.; Caloba, L.; Carvalho, J.; Casado, P.; Castillo, M.V.; Cavalli-Sforza, M.; Cavasinni, V.; Chadelas, R.; Chirikov-Zorin, I.; Chlachidze, G.; Cobal, M.; Cogswell, F.; Colaco, F.; Cologna, S.; Constantinescu, S.; Costanzo, D.; Crouau, M.; Daudon, F.; David, J.; David, M.; Davidek, T.; Dawson, J.; De, K.; Del Prete, T.; De Santo, A.; Di Girolamo, B.; Dita, S.; Dolejsi, J.; Dolezal, Z.; Downing, R.; Efthymiopoulos, I.; Engstroem, M.; Errede, D.; Errede, S.; Evans, H.; Fenyuk, A.; Ferrer, A.; Flaminio, V.; Gallas, E.; Gaspar, M.; Gil, I.; Gildemeister, O.; Glagolev, V.; Gomes, A.; Gonzalez, V.; Gonzalez De La Hoz, S.; Grabski, V.; Grauges, E.; Grenier, P.; Hakopian, H.; Haney, M.; Hansen, M.; Hellman, S.; Henriques, A.; Hebrard, C.; Higon, E.; Holmgren, S.; Huston, J.; Ivanyushenkov, Yu.; Jon-And, K.; Juste, A.; Kakurin, S.; Karapetian, G.; Karyukhin, A.; Kopikov, S.; Kukhtin, V.; Kulchitsky, Y.; Kurzbauer, W.; Kuzmin, M.; Lami, S.; Lapin, V.; Lazzeroni, C.; Lebedev, A.; Leitner, R.; Li, J.; Lomakin, Yu.; Lomakina, O.; Lokajicek, M.; Lopez Amengual, J.M.; Maio, A.; Malyukov, S.; Marroquin, F.; Martins, J.P.; Mazzoni, E.; Merritt, F.; Miller, R.; Minashvili, I.; Miralles, Ll.; Montarou, G.; Munar, A.; Nemecek, S.; Nessi, M. E-mail: marzio.nessi@cern.ch; Onofre, A.; Orteu, S.; Park, I.C.; Pallin, D.; Pantea, D.; Paoletti, R.; Patriarca, J.; Pereira, A.; Perlas, J.A.; Petit, P.; Pilcher, J.; Pinhao, J.; Poggioli, L.; Price, L.; Proudfoot, J.; Pukhov, O.; Reinmuth, G.; Renzoni, G.; Richards, R.; Roda, C.; Romance, J.B.; Romanov, V.; Ronceux, B.; Rosnet, P.; Rumyantsev, V.; Russakovich, N.; Sanchis, E.; Sanders, H.; Santoni, C.; Santos, J.; Sawyer, L.; Says, L.-P.; Seixas, J.M.; Sellden, B.; Semenov, A.; Shchelchkov, A.; Shochet, M.; Simaitis, V. [and others

    2000-03-21

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

  11. Particle flow calorimetry at the international linear collider

    Indian Academy of Sciences (India)

    Mark A Thomson

    2007-12-01

    One of the most important requirements for a detector at the ILC is good jet energy resolution. It is widely believed that the particle flow approach to calorimetry is the key to achieving the goal of $0.3/\\sqrt{E(GeV)}$. This paper describes the current performance of the PandoraPFA particle flow algorithm. For 45 GeV jets in the Tesla TDR detector concept, the ILC jet energy resolution goal is reached. At higher energies the jet energy resolution becomes worse and can be described by the empirical expression: $_{E}/E ≈ 0.265/\\sqrt{E(GeV)} + 1.2 times 10^{-4} E(GeV)$.

  12. A Statistical Method and Tool to Account for Indirect Calorimetry Differential Measurement Error in a Single-Subject Analysis.

    Science.gov (United States)

    Tenan, Matthew S

    2016-01-01

    Indirect calorimetry and oxygen consumption (VO2) are accepted tools in human physiology research. It has been shown that indirect calorimetry systems exhibit differential measurement error, where the error of a device is systematically different depending on the volume of gas flow. Moreover, systems commonly report multiple decimal places of precision, giving the clinician a false sense of device accuracy. The purpose of this manuscript is to demonstrate the use of a novel statistical tool which models the reliability of two specific indirect calorimetry systems, Douglas bag and Parvomedics 2400 TrueOne, as univariate normal distributions and implements the distribution overlapping coefficient to determine the likelihood that two VO2 measures are the same. A command line implementation of the tool is available for the R programming language as well as a web-based graphical user interface (GUI). This tool is valuable for clinicians performing a single-subject analysis as well as researchers interested in determining if their observed differences exceed the error of the device.

  13. A Statistical Method and Tool to Account for Indirect Calorimetry Differential Measurement Error in a Single-Subject Analysis

    Directory of Open Access Journals (Sweden)

    Matthew S Tenan

    2016-05-01

    Full Text Available Indirect calorimetry and oxygen consumption (VO2 are accepted tools in human physiology research. It has been shown that indirect calorimetry systems exhibit differential measurement error, where the error of a device is systematically different depending on the volume of gas flow. Moreover, systems commonly report multiple decimal places of precision, giving the clinician a false sense of device accuracy. The purpose of this manuscript is to demonstrate the use of a novel statistical tool which models the reliability of two specific indirect calorimetry systems, Douglas bag and Parvomedics 2400 TrueOne, as univariate normal distributions and implements the distribution overlapping coefficient to determine the likelihood that two VO2 measures are the same. A command line implementation of the tool is available for the R programming language as well as a web-based graphical user interface. This tool is valuable for clinicians performing a single-subject analysis as well as researchers interested in determining if their observed differences exceed the error of the device.

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

    Science.gov (United States)

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

    2010-10-31

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

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

    Science.gov (United States)

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

    1985-01-01

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

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

    Science.gov (United States)

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

    2016-01-01

    Isothermal titration calorimetry was applied to study the binding of purified proanthocyanidin oligomers to bovine serum albumin (BSA). The molecular weight of the proanthocyanidin oligomer had a major impact on its binding to BSA. The calculated change in enthalpy (ΔH) and association constant (Ka) became greater as the oligomer size increased then plateaued at the heptameric oligomer. These results support a model for precipitation of proteins by proanthocyanidin where increased oligomer size enhanced the opportunity for cross linkages between proteins ultimately forming sediment-able complexes. The authors suggest tannin binding to proteins is opportunistic and involves multiple sites, each with a different Ka and ΔH of binding. The ΔH of binding comprises both an endothermic hydrophobic interaction and exothermic hydrogen bond component. This suggests the calculated entropy value (ΔS) for tannin-protein interactions is subject to a systematic error and should be interpreted with caution. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

    CERN Document Server

    Jeembaeva, Meerim; Castelnovo, Martin; Evilevitch, Alex

    2010-01-01

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

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

    Science.gov (United States)

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

    2016-08-01

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

  19. Analysis of the Escherichia coli glucosamine-6-phosphate synthase activity by isothermal titration calorimetry and differential scanning calorimetry.

    Science.gov (United States)

    Valerio-Lepiniec, Marie; Aumont-Nicaise, Magali; Roux, Céline; Raynal, Bertrand; England, Patrick; Badet, Bernard; Badet-Denisot, Marie-Ange; Desmadril, Michel

    2010-06-15

    Glucosamine-6-phosphate synthase (GlmS) is responsible for the first and rate-limiting step in the hexosamine biosynthetic pathway. It catalyzes the conversion of D-fructose-6P (F6P) into D-glucosamine-6P (GlcN6P) using L-glutamine (Gln) as nitrogen donor (synthase activity) according to an ordered bi-bi process where F6P binds first. In the absence of F6P, the enzyme exhibits a weak hydrolyzing activity of Gln into Glu and ammonia (glutaminase activity), whereas the presence of F6P strongly stimulates it (hemi-synthase activity). Until now, these different activities were indirectly measured using either coupled enzyme or colorimetric methods. In this work, we have developed a direct assay monitoring the heat released by the reaction. Isothermal titration calorimetry and differential scanning calorimetry were used to determine kinetic and thermodynamic parameters of GlmS. The direct determination at 37 degrees C of kinetic parameters and affinity constants for both F6P and Gln demonstrated that part of the ammonia produced by Gln hydrolysis in the presence of both substrates is not used for the formation of the GlcN6P. The full characterization of this phenomenon allowed to identify experimental conditions where this leak of ammonia is negligible. Enthalpy measurements at 25 degrees C in buffers of various heats of protonation demonstrated that no proton exchange with the medium occurred during the enzyme-catalyzed glutaminase or synthase reaction suggesting for the first time that both products are released as a globally neutral pair composed by the Glu carboxylic side chain and the GlcN6P amine function. Finally we showed that the oligomerization state of GlmS is concentration-dependent. Copyright (c) 2010 Elsevier Inc. All rights reserved.

  20. An evaluation of the use of calorimetry for shipper-receiver measurements of plutonium

    Energy Technology Data Exchange (ETDEWEB)

    Rodenburg, W.W.

    1977-12-01

    The purpose of this report is to evaluate the relative merit of using calorimetry for shipper-receiver (S-R) exchanges of Pu. In particular, this evaluation concentrates on the accountability and the diversion detection aspects of calorimetry. Three different modes of use were considered: (1) calorimetry alone, that is S-R exchanges based on power (wattage) measurements; (2) calorimetry plus chemical assay, similar to the present weight plus chemical assay system, and (3) calorimetry plus gamma-ray spectrometry, a totally nondestructive Pu assay method. The relative merit of ball three applications was judged using the present methods as a base case. Some of the factors considered were random and systematic errors, timeliness, costs (both operating and capital) and reliability.

  1. Irreversible denaturation of maltodextrin glucosidase studied by differential scanning calorimetry, circular dichroism, and turbidity measurements.

    Science.gov (United States)

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

    2014-01-01

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

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

    Science.gov (United States)

    Sassowsky, M; Pedroni, E

    2005-11-21

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

  3. ANALYSIS OF BRANCHING DISTRIBUTION IN POLYETHYLENES BY DIFFERENTIAL SCANNING CALORIMETRY

    Institute of Scientific and Technical Information of China (English)

    Robert Shanks; Fei Chen; Gandara Amarasinghe

    2003-01-01

    Short chain branching has been characterized using thermal fractionation, a stepwise isothermal crystallization technique, followed by a melting analysis scan using differential scanning calorimetry. Short chain branching distribution was also characterized by a continuous slow cooling crystallization, followed by a melting analysis scan. Four different polyethylenes were studied: Ziegler-Natta gas phase, Ziegler-Natta solution, metallocene, constrained-geometry single site catalyzed polyethylenes. The branching distribution was calculated from a calibration of branch content with melting temperature. The lamellar thickness was calculated based on the thermodynamic melting temperature of each polyethylene and the surface free energy of the crystal face. The branching distribution and lamellar thickness distribution were used to calculate weight average branch content, mean lamellar thickness, and a branch dispersity index. The results for the branch content were in good agreement with the known comonomer content of the polyethylenes. A limitation was that high branch content polyethylenes did not reach their potential crystallization at ambient temperatures. Cooling to sub-ambient was necessary to equilibrate the crystallization, but melting temperature versus branch content was not applicable after cooling to below ambient because the calibration data were not performed in this way.

  4. ANALYSIS OF BRANCHING DISTRIBUTION IN POLYETHYLENES BY DIFFERENTIAL SCANNING CALORIMETRY

    Institute of Scientific and Technical Information of China (English)

    RobertShanks; FeiChan; GandaraAmarasinghe; RobertShanks

    2003-01-01

    Short chain branching has been characterized using thermal fractionation,a stepwise isothermal crystallization technique,followed by a melting analysis scan using differential scanning calorimetry.Short chain branching distribution was also characterized by a continuous slow cooling crystallization,followed by a melting analysis scan.Four different polyethylenes were studied:Ziegler-Natta gas phase,Ziegler-Natta solution,metallocene,constrained-geometry single site catalyzed polyethylenes.The branching distribution was calculated from a calibration of branch content with melting temperature.The lamellar thickness was calculated based on the thermodynamic melting temperature of each polyethylene and the surface free energy of the crystal face.The branching distribution and lamellar thickness distribution were used to calculate weight average branch content,mean lamellar thickness,and a branch dispersity index.The results for the branch content were in good agreement with the known comonomer content of the polyethylenes.A limitation was that high branch content polyethylenes did not reach their potential crystallization at ambient temperatures.Cooling to sub-ambient was necessary to equilibrate the crystallization,but melting temperature versus branch content was not applicable after cooling to below ambient because the calibration data were not performed in this way.

  5. Application of pressure perturbation calorimetry to lipid bilayers.

    Science.gov (United States)

    Heerklotz, Heiko; Seelig, Joachim

    2002-03-01

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

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

    Science.gov (United States)

    Mazzei, Luca; Ciurli, Stefano; Zambelli, Barbara

    2014-04-04

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

  7. Application of isothermal titration calorimetry in bioinorganic chemistry.

    Science.gov (United States)

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

    2010-11-01

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

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

    Science.gov (United States)

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

    2010-11-01

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

  9. Measuring Multivalent Binding Interactions by Isothermal Titration Calorimetry.

    Science.gov (United States)

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

    2016-01-01

    Multivalent glycoconjugate-protein interactions are central to many important biological processes. Isothermal titration calorimetry (ITC) can potentially reveal the molecular and thermodynamic basis of such interactions. However, calorimetric investigation of multivalency is challenging. Binding of multivalent glycoconjugates to proteins (lectins) often leads to a stoichiometry-dependent precipitation process due to noncovalent cross-linking between the reactants. Precipitation during ITC titration severely affects the quality of the baseline as well as the signals. Hence, the resulting thermodynamic data are not dependable. We have made some modifications to address this problem and successfully studied multivalent glycoconjugate binding to lectins. We have also modified the Hill plot equation to analyze high quality ITC raw data obtained from multivalent binding. As described in this chapter, ITC-driven thermodynamic parameters and Hill plot analysis of ITC raw data can provide valuable information about the molecular mechanism of multivalent lectin-glycoconjugate interactions. The methods described herein revealed (i) the importance of functional valence of multivalent glycoconjugates, (ii) that favorable entropic effects contribute to the enhanced affinities associated with multivalent binding, (iii) that with the progression of lectin binding, the microscopic affinities of the glycan epitopes of a multivalent glycoconjugate decrease (negative cooperativity), (iv) that lectin binding to multivalent glycoconjugates, especially to mucins, involves internal diffusion jumps, (bind and jump) and (v) that scaffolds of glycoconjugates influence their entropy of binding. © 2016 Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

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

    2014-10-23

    Understanding the structure, folding, and interaction of membrane proteins requires experimental tools to quantify the association of transmembrane (TM) helices. Here, we introduce isothermal titration calorimetry (ITC) to measure integrin αIIbβ3 TM complex affinity, to study the consequences of helix-helix preorientation in lipid bilayers, and to examine protein-induced lipid reorganization. Phospholipid bicelles served as membrane mimics. The association of αIIbβ3 proceeded with a free energy change of -4.61±0.04kcal/mol at bicelle conditions where the sampling of random helix-helix orientations leads to complex formation. At bicelle conditions that approach a true bilayer structure in effect, an entropy saving of >1kcal/mol was obtained from helix-helix preorientation. The magnitudes of enthalpy and entropy changes increased distinctly with bicelle dimensions, indicating long-range changes in bicelle lipid properties upon αIIbβ3 TM association. NMR spectroscopy confirmed ITC affinity measurements and revealed αIIbβ3 association and dissociation rates of 4500±100s(-1) and 2.1±0.1s(-1), respectively. Thus, ITC is able to provide comprehensive insight into the interaction of membrane proteins. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Hot Biological Catalysis: Isothermal Titration Calorimetry to Characterize Enzymatic Reactions

    Science.gov (United States)

    Mazzei, Luca; Ciurli, Stefano; Zambelli, Barbara

    2014-01-01

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

  12. Novel investigation of enzymatic biodiesel reaction by isothermal calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Sotoft, Lene Fjerbaek, E-mail: lfj@kbm.sdu.dk [Institute of Chemical Engineering, Biotechnology and Environmental Technology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M (Denmark); Westh, Peter [Department of Life Science and Chemistry, Roskilde University, PO Box 260, DK-4000 Roskilde (Denmark); Christensen, Knud V.; Norddahl, Birgir [Institute of Chemical Engineering, Biotechnology and Environmental Technology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M (Denmark)

    2010-03-30

    Isothermal calorimetry (ITC) was used to investigate solvent-free enzymatic biodiesel production. The transesterification of rapeseed oil with methanol and ethanol was catalyzed by immobilized lipase Novozym 435 at 40 {sup o}C. The aim of the study was to determine reaction enthalpy for the enzymatic transesterification and to elucidate the mass transfer and energetic processes taking place. Based on the measured enthalpy and composition change in the system, the heat of reaction at 40 {sup o}C for the two systems was determined as -9.8 {+-} 0.9 kJ/mole biodiesel formed from rapeseed oil and methanol, and -9.3 {+-} 0.7 kJ/mole when rapeseed oil and ethanol was used. Simple Michaelis-Menten kinetics was not an appropriate choice for describing the kinetics of this heterogeneous system. The experiments demonstrated the possibility of investigating complex reaction mixtures using ITC. Although it is possible to determine thermodynamic properties such as reaction enthalpy and reaction rate, the difficulty in actually measuring the true non-mass-transfer-limited reaction kinetics is exposed by the high time resolution of ITC.

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

    Science.gov (United States)

    Cizmecioglu, M.; Gupta, A.

    1982-01-01

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

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

    Science.gov (United States)

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

    2015-01-01

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

  15. Study of Liquid Argon Dopants for LHC Hadron Calorimetry

    CERN Multimedia

    2002-01-01

    Hadron calorimetry based on the Liquid Argon Ionisation Chamber technique is one of the choice techniques for LHC-experimentation. A systematic study of the effect of selected dopants on Liquid Argon (LAr) will be carried out with the aim to achieve an improvement on: \\item (i)~``Fast Liquid Argon'' search and study of dopants to increase the drift velocity. It has been already shown that CH&sub4. added at a fraction of one percent increases the drift velocity by a factor of two or more. \\item (ii)~``Compensated Liquid Argon'' search and study of dopants to increase the response to densely ionising particles, resulting in improved compensation, such as photosensitive dopants. \\end{enumerate}\\\\ \\\\ Monitoring of the parameters involved in understanding the response of a calorimeter is essential. In case of doped LAr, the charge yield, the non-saturated drift velocity and the electron lifetime in the liquid should be precisely and simultaneously monitored as they all vary with the level of dopant concentrati...

  16. [Differential scanning calorimetry of blood plasma in breast cancer patients].

    Science.gov (United States)

    Zapf, István; Fekecs, Tamás; Moezzi, Medhi; Tizedes, György; Pavlovics, Gábor; Kálmán, Endre; Horváth, Péter Ors; Ferencz, Andrea

    2012-12-01

    Breast cancer is the commonest cause of cancer death in women worldwide. Its incidence has been increasing for many years in economically developed countries. Differential scanning calorimetry (DSC) is a thermoanalytical technique which monitors small heat changes between sample and reference materials. This examination is a validly efficient method for the demonstration of structural changes not only in the physical sciences, but in numerous human oncological diseases. The goal of this study was to measure DSC thermogram of blood plasma in breast cancer patients with different stages. Nineteen women with different tumor diameter (0.5-7.5 mm) and with or without regional lymph node metastases were involved in the study. Preoperatively peripheral blood samples were collected from the patients and from healthy controls, and plasma components were analysed by SETARAM micro DSC-II calorimeter. The diameter of the tumor tissue and the number of metastatic lymph nodes were evaluated on the basis of postoperative histological results. In the current study we found difference in changes of the thermal parameters (transition temperature, calorimetric enthalpy) of breast cancer patients' plasma components. Moreover, a tendency has been found for association of these results with tumor size and with the degree of regional lymph node involvement. Preliminary study of the clinical utility of DSC technology arises, even though there is no data in the literature. In cases of breast cancer the blood plasma may be suitable for DSC analysis for diagnosis or staging as well. In order to clarify the relationships we are planning further studies.

  17. The deconvolution of differential scanning calorimetry unfolding transitions.

    Science.gov (United States)

    Spink, Charles H

    2015-04-01

    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. Copyright © 2014. Published by Elsevier Inc.

  18. Differential scanning calorimetry to investigate G-quadruplexes structural stability.

    Science.gov (United States)

    Pagano, Bruno; Randazzo, Antonio; Fotticchia, Iolanda; Novellino, Ettore; Petraccone, Luigi; Giancola, Concetta

    2013-11-01

    Differential Scanning Calorimetry (DSC) is a straightforward methodology to characterize the energetics of thermally-induced transitions of DNA and other biological macromolecules. Therefore, DSC has been used to study the thermodynamic stability of several nucleic acids structures. G-quadruplexes are among the most important non-canonical nucleic acid architectures that are receiving great consideration. This article reports examples on the contribution of DSC to the knowledge of G-quadruplex structures. The selected case studies show the potential of this method in investigating the structure stability of G-quadruplex forming nucleic acids, and in providing information on their structural complexity. Indeed, DSC can determine thermodynamic parameters of G-quadruplex folding/unfolding processes, but it can also be useful to reveal the formation of multiple conformations or the presence of intermediate states along the unfolding pathway, and to evaluate the impact of chemical modifications on their structural stability. This article aims to show that DSC is an important complementary methodology to structural techniques, such as NMR and X-ray crystallography, in the study of G-quadruplex forming nucleic acids. Copyright © 2013 Elsevier Inc. All rights reserved.

  19. Differential Scanning Calorimetry (DSC) for planetary surface exploration

    Science.gov (United States)

    Gooding, James L.; Ming, Douglas W.

    1993-01-01

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

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

    Science.gov (United States)

    Cizmecioglu, M.; Gupta, A.

    1982-01-01

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

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

    Science.gov (United States)

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

    2010-01-01

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

  2. The Electromagnetic Calorimetry of the PANDA Detector at FAIR

    Science.gov (United States)

    Novotny, R. W.; PANDA Collaboration

    2012-12-01

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

  3. Applying fast calorimetry on a spent nuclear fuel calorimeter

    Energy Technology Data Exchange (ETDEWEB)

    Liljenfeldt, Henrik [Swedish Nuclear Fuel and Waste Management (Sweden); Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Uppsala Univ. (Sweden)

    2015-04-15

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

  4. Adiabatic calorimetry (RSST and VSP) tests with sodium acetate

    Energy Technology Data Exchange (ETDEWEB)

    Kirch, N.W.

    1993-09-01

    As requested in the subject reference, adiabatic calorimetry (RSST and VSP) tests have been performed with sodium acetate covering TOC concentrations from 3 to 7% with the following results: Exothermic activity noted around 200{degrees}C. Propagating reaction initiated at about 300{degrees}C. Required TOC concentration for propagation estimated at about 6 w% (dry mixture) or about 20 w% sodium acetate. Heat of reaction estimated to be 3.7 MJ per kg of sodium acetate (based on VSP test with 3 w% TOC and using a dry mixture specific heat of 1000 J kg{sup {minus}1} K{sup {minus}1}). Based upon the above results we estimate that a moisture content in excess of 14 w% would prevent a propagating reaction of a stoichiometric mixture of fuel and oxidizer ({approximately} 38 w% sodium acetate and {approximately}62 w% sodium nitrate). Assuming that the fuel can be treated as sodium acetate equivalent, and considering that the moisture content in the organic containing waste generally is believed to be in excess of 14 w%, it follows that the possibility of propagating reactions in the Hanford waste tanks can be ruled out.

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

    Science.gov (United States)

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

    2013-01-01

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

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

    Science.gov (United States)

    Wang, Yifang

    2011-03-01

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

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

    Science.gov (United States)

    Wang, Bin; Jia, Yuan; Lin, Qiao

    2016-04-15

    Isothermal titration calorimetry (ITC) directly measures heat evolved in a chemical reaction to determine equilibrium binding properties of biomolecular systems. Conventional ITC instruments are expensive, use complicated design and construction, and require long analysis times. Microfabricated calorimetric devices are promising, although they have yet to allow accurate, quantitative ITC measurements of biochemical reactions. This paper presents a microfabrication-based approach to integrated, quantitative ITC characterization of biomolecular interactions. The approach integrates microfabricated differential calorimetric sensors with microfluidic titration. Biomolecules and reagents are introduced at each of a series of molar ratios, mixed, and allowed to react. The reaction thermal power is differentially measured, and used to determine the thermodynamic profile of the biomolecular interactions. Implemented in a microdevice featuring thermally isolated, well-defined reaction volumes with minimized fluid evaporation as well as highly sensitive thermoelectric sensing, the approach enables accurate and quantitative ITC measurements of protein-ligand interactions under different isothermal conditions. Using the approach, we demonstrate ITC characterization of the binding of 18-Crown-6 with barium chloride, and the binding of ribonuclease A with cytidine 2'-monophosphate within reaction volumes of approximately 0.7 µL and at concentrations down to 2mM. For each binding system, the ITC measurements were completed with considerably reduced analysis times and material consumption, and yielded a complete thermodynamic profile of the molecular interaction in agreement with published data. This demonstrates the potential usefulness of our approach for biomolecular characterization in biomedical applications. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Calorimetry at the international linear collider. From simulation to reality

    Energy Technology Data Exchange (ETDEWEB)

    Wattimena, Nanda

    2010-02-15

    Calorimetry plays a crucial role in ongoing and upcoming high-energy physics experiments. To build a powerful calorimetric system with a performance tailored to the expected physics signatures, demands dedicated research and development of new readout technologies as well as dedicated reconstruction algorithms. The presented design of a calorimetric system which meets the high demands of precision physics at the future linear collider ILC, follows the paradigm of particle ow. Particle ow is a reconstruction principle that relies on a calorimetric system with high spatial granularity. In the detector optimisation process, the development of hardware and software are interlinked and cannot be judged independently. This thesis addresses two different aspects of detector optimisation, a test of the detector design against one example physics scenario and the development of a stable calibration procedure. In the rst part, a gauge-mediated Supersymmetry breaking scenario is used to test the design of the electromagnetic calorimeter in a full detector simulation study. The reconstruction of the neutralino properties, each decaying into a photon and a gravitino, requires a good energy resolution, as well as excellent position and angular resolution. The error bounds on the neutralino mass is strongly linked to the energy resolution, while the position and angular reconstruction of neutral particles is essential for the determination of the neutralino lifetime. The second part of this thesis focuses on the calibration procedure for a prototype of the hadron calorimeter. 7608 novel photodetectors are operated and tested in this prototype. They are exposed to beams of well de ned particle type and energy. The calibration is tested with a detailed study of electromagnetic showers inside the cubic-metre-sized prototype, with special attention paid towards the non-linearity correction. (orig.)

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

    Science.gov (United States)

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

    2015-04-01

    Isothermal titration calorimetry (ITC) has become the gold-standard technique for studying binding processes due to its high precision and sensitivity, as well as its capability for the simultaneous determination of the association equilibrium constant, the binding enthalpy and the binding stoichiometry. The current widespread use of ITC for biological systems has been facilitated by technical advances and the availability of commercial calorimeters. However, the complexity of data analysis for non-standard models is one of the most significant drawbacks in ITC. Many models for studying macromolecular interactions can be found in the literature, but it looks like each biological system requires specific modeling and data analysis approaches. The aim of this article is to solve this lack of unity and provide a unified methodological framework for studying binding interactions by ITC that can be applied to any experimental system. The apparent complexity of this methodology, based on the binding polynomial, is overcome by its easy generalization to complex systems. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Deconvolution of complex differential scanning calorimetry profiles for protein transitions under kinetic control.

    Science.gov (United States)

    Toledo-Núñez, Citlali; Vera-Robles, L Iraís; Arroyo-Maya, Izlia J; Hernández-Arana, Andrés

    2016-09-15

    A frequent outcome in differential scanning calorimetry (DSC) experiments carried out with large proteins is the irreversibility of the observed endothermic effects. In these cases, DSC profiles are analyzed according to methods developed for temperature-induced denaturation transitions occurring under kinetic control. In the one-step irreversible model (native → denatured) the characteristics of the observed single-peaked endotherm depend on the denaturation enthalpy and the temperature dependence of the reaction rate constant, k. Several procedures have been devised to obtain the parameters that determine the variation of k with temperature. Here, we have elaborated on one of these procedures in order to analyze more complex DSC profiles. Synthetic data for a heat capacity curve were generated according to a model with two sequential reactions; the temperature dependence of each of the two rate constants involved was determined, according to the Eyring's equation, by two fixed parameters. It was then shown that our deconvolution procedure, by making use of heat capacity data alone, permits to extract the parameter values that were initially used. Finally, experimental DSC traces showing two and three maxima were analyzed and reproduced with relative success according to two- and four-step sequential models. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Differential scanning calorimetry as a complementary diagnostic tool for the evaluation of biological samples.

    Science.gov (United States)

    Garbett, Nichola C; Brock, Guy N

    2016-05-01

    Differential scanning calorimetry (DSC) is a tool for measuring the thermal stability profiles of complex molecular interactions in biological fluids. DSC profiles (thermograms) of biofluids provide specific signatures which are being utilized as a new diagnostic approach for characterizing disease but the development of these approaches is still in its infancy. This article evaluates several approaches for the analysis of thermograms which could increase the utility of DSC for clinical application. Thermograms were analyzed using localized thermogram features and principal components (PCs). The performance of these methods was evaluated alongside six models for the classification of a data set comprised of 300 systemic lupus erythematosus (SLE) patients and 300 control subjects obtained from the Lupus Family Registry and Repository (LFRR). Classification performance was substantially higher using the penalized algorithms relative to localized features/PCs alone. The models were grouped into two sets, the first having smoother solution vectors but lower classification accuracies than the second with seemingly noisier solution vectors. Coupling thermogram technology with modern classification algorithms provides a powerful diagnostic approach for analysis of biological samples. The solution vectors from the models may reflect important information from the thermogram profiles for discriminating between clinical groups. DSC thermograms show sensitivity to changes in the bulk plasma proteome that correlate with clinical status. To move this technology towards clinical application the development of new approaches is needed to extract discriminatory parameters from DSC profiles for the comparison and diagnostic classification of patients. Copyright © 2015 Elsevier B.V. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2001-12-31

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

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

    Science.gov (United States)

    Stroud, Mary W.

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

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

    Science.gov (United States)

    Sokoloski, Joshua E; Bevilacqua, Philip C

    2012-01-01

    Noncoding RNAs serve myriad functions in the cell, but their biophysical properties are not well understood. Calorimetry offers direct and label-free means for characterizing the ligand-binding and thermostability properties of these RNA. We apply two main types of calorimetry--isothermal titration calorimetry (ITC) and differential scanning calorimetry (DSC)--to the characterization of these functional RNA molecules. ITC can describe ligand binding in terms of stoichiometry, affinity, and heat (enthalpy), while DSC can provide RNA stability in terms of heat capacity, melting temperature, and folding enthalpy. Here, we offer detailed experimental protocols for studying such RNA systems with commercially available conventional and high-throughput ITC and DSC instruments.

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

    Science.gov (United States)

    Temme, Susan M.

    1995-01-01

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

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

    Science.gov (United States)

    Muyskens, Mark A.

    1997-01-01

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

  17. Parallelism between gradient temperature raman spectroscopy and differential scanning calorimetry results

    Science.gov (United States)

    Temperature dependent Raman spectroscopy (TDR) applies the temperature gradients utilized in differential scanning calorimetry (DSC) to Raman spectroscopy, providing a straightforward technique to identify molecular rearrangements that occur just prior to phase transitions. Herein we apply TDR and D...

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

    Science.gov (United States)

    Temme, Susan M.

    1995-01-01

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

  19. Proposal for continuing studies on lead/scintillating fibres calorimetry (LFC)

    CERN Document Server

    Anzivino, Giuseppina; Bari, G; Basile, M; Bellagamba, L; Bencheikh, C; Boscherini, D; Bruni, G; Bruni, P; Buzuloiu, V; Cara Romeo, G; Chiarini, M; Cifarelli, Luisa; Cindolo, F; Ciralli, F; Contin, A; Dardo, M; De Pasquale, S; DeSalvo, R; Frasconi, F; Gheorghe, A; Giusti, P; Hao, E; Iacobucci, G; Laurenti, G; Lundin, M; Maccarrone, G D; Margotti, A; Massam, Thomas; Mondardini, M R; Nania, R; Peskov, Vladimir; Sartorelli, G; Scioni, M; Timellini, R; Wang, Y; Xu, C; You, K; Zichichi, Antonino; CERN. Geneva. Detector Research and Development Committee

    1991-01-01

    Starting from the results obtained in the framework of the LAA Project 2B, we propose a continuation of the R&D on lead/scintillating fibres calorimetry ("spaghetti calorimetry"), including further tests on the old calorimeter prototypes and the construction and testing of new prototypes. The main results we pursue concern the performances of a projective calorimeter built with new, cheaper techniques and the radiation hardness of the scintillating fibres; the optimization of a preshower detector system is also studied.

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

    OpenAIRE

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

    2017-01-01

    In this paper we report a newly developed technique – laser calorimetry spectroscopy (LCS), which is a combination of laser absorption spectroscopy and calorimetry - for the detection of gases dissolved in liquids. The technique involves determination of concentration of a dissolved gas by irradiating the liquid with light of a wavelength where the gas absorbs, and measuring the temperature change caused by the absorbance. Conventionally, detection of dissolved gases with sufficient sensitivi...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-07-02

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

  2. Differential scanning calorimetry and fluorimetry measurements of monoclonal antibodies and reference proteins: Effect of scanning rate and dye selection.

    Science.gov (United States)

    Lang, Brian E; Cole, Kenneth D

    2017-05-01

    Differential scanning calorimetry (DSC) and differential scanning fluorimetry (DSF) were used to measure the transition temperatures of four proteins: RNase A, invertase, rituximab, and the NISTmAb (NIST Reference Material, RM 8671). The proteins were combined with several different fluorescent dyes for the DSF measurements. This study compares the results of DSC and DSF measurements of transition temperatures with different types of proteins, dye combinations, and thermal scan rates. As protein unfolding is often influenced by kinetic effects, we measured the transition temperatures of the proteins using DSC over a range of temperature scan rates and compared them to the data obtained from DSF over comparable temperature scan rates. The results when the proteins were combined with Sypro Orange(®) and bis-ANS for the DSF measurements had the best correlations with the transition temperatures determined by calorimetry. The scan rate was found to be an important variable when comparing results between DSC and DSF. The van't Hoff enthalpy changes for the transitions were calculated from the DSC data by using a non-two-state model and from the DSF values using a two-state model. The calculated van't Hoff enthalpy changes did not show a good correlation between the two methods. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:677-686, 2017. © 2017 American Institute of Chemical Engineers.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-01-01

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

  4. Advances in the analysis of isothermal titration calorimetry data for ligand-DNA interactions.

    Science.gov (United States)

    Buurma, Niklaas J; Haq, Ihtshamul

    2007-06-01

    Isothermal titration calorimetry (ITC) is a well established technique for the study of biological interactions. The strength of ITC is that it directly measures enthalpy changes associated with interactions. Experiments can also yield binding isotherms allowing quantification of equilibrium binding constants, hence an almost complete thermodynamic profile can be established. Principles and application of ITC have been well documented over recent years, experimentally the technique is simple to use and in ideal scenarios data analysis is trivial. However, ITC experiments can be designed such that previously inaccessible parameters can be evaluated. We outline some of these advances, including (1) exploiting different experimental conditions; (2) low affinity systems; (3) high affinity systems and displacement assays. In addition we ask the question: What if data cannot be fit using the fitting functions incorporated in the data-analysis software that came with your ITC? Examples where such data might be generated include systems following non 1:n binding patterns and systems where binding is coupled to other events such as ligand dissociation. Models dealing with such data are now appearing in literature and we summarise examples relevant for the study of ligand-DNA interactions.

  5. Vascular Endothelial Growth Factor Peptide Ligands Explored by Competition Assay and Isothermal Titration Calorimetry.

    Science.gov (United States)

    Reille-Seroussi, Marie; Gaucher, Jean-François; Desole, Claudia; Gagey-Eilstein, Nathalie; Brachet, Franck; Broutin, Isabelle; Vidal, Michel; Broussy, Sylvain

    2015-08-25

    The v114* cyclic peptide has been identified as a tight vascular endothelial growth factor (VEGF) ligand. Here we report on the use of isothermal titration calorimetry (ITC), 96-well plate competition assay, and circular dichroism (CD) to explore the binding determinants of a new set of related peptides. Anti-VEGF antibodies are currently used in the clinic for regulating angiogenesis in cancer and age-related macular degeneration treatment. In this context, our aim is to develop smaller molecular entities with high affinity for the growth factor by a structure activity relationship approach. The cyclic disulfide peptide v114* was modified in several ways, including truncation, substitution, and variation of the size and nature of the cycle. The results indicated that truncation or substitution of the four N-terminal amino acids did not cause severe loss in affinity, allowing potential peptide labeling. Increase of the cycle size or substitution of the disulfide bridge with a thioether linkage drastically decreased the affinity, due to an enthalpy penalty. The leucine C-terminal residue positively contributed to affinity. Cysteine N-terminal acetylation induced favorable ΔΔG° and ΔΔH° of binding, which correlated with free peptide CD spectra changes. We also propose a biochemical model to extrapolate Ki from IC50 values measured in the displacement assay. These calculated Ki correlate well with the Kd values determined by extensive direct and reverse ITC measurements.

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

    Science.gov (United States)

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

    2008-01-01

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

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

    Science.gov (United States)

    2011-01-01

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

  8. A Guide to Differential Scanning Calorimetry of Membrane and Soluble Proteins in Detergents.

    Science.gov (United States)

    Yang, Zhengrong; Brouillette, Christie G

    2016-01-01

    Differential scanning calorimetry (DSC) detects protein thermal unfolding by directly measuring the heat absorbed. Simple DSC experiments that require relatively small amounts of pure material can provide a wealth of information related to structure, especially with respect to domain architecture, without the need for a complete thermodynamic analysis. Thus, DSC is an ideal additional tool for membrane protein characterization and also offers several advantages over indirect thermal unfolding methods. Integral membrane proteins (IMPs) that comprise both large multitopic transmembrane domains (TMDs) and extramembranous domains (EMDs) are differentially affected by detergent interactions with both domains. In fact, in some cases, destabilization of the EMD by detergent may dominate overall IMP stability. This chapter will (1) provide a perspective on the advantages of DSC for membrane protein characterization and stability measurements, including numerous examples spanning decades of research; (2) introduce models for the interaction and destabilization of IMPs by detergents; (3) discuss two case studies from the authors' lab; and (4) offer practical advice for performing DSC in the presence of detergents.

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

    Science.gov (United States)

    Cavan, A.; Meyer, J.

    2013-06-01

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

  10. Investigations of cosmetically treated human hair by differential scanning calorimetry in water.

    Science.gov (United States)

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

    2002-01-01

    By applying differential scanning calorimetry (DSC) on human hair in water, the thermal stability of hair' major morphological components is determined. Against the background of the two-phase model for alpha-keratins, these components are identified as the partially helical, fibrous intermediate filaments (IF) and the intermediate filament associated-proteins (IFAP) as a cross-linked, amorphous matrix. DSC yields the denaturation enthalpy deltaH(D), which depends on the amount and structural integrity of the alpha-helical material, and the temperature T(D), which is kinetically controlled by the cross-link density of the matrix. To assess the effects of cosmetic treatments, hairs were investigated that had undergone either multiple bleaching or perm-waving treatments. The respective dependencies between denaturation temperature and enthalpy show that both morphological components are similarly affected by bleaching, while reductive damage, in comparison, is more pronounced in the IFs. For both types of treatments, changes in enthalpy follow apparent first-order kinetics with respect to the number of treatments as well as treatment time (perm-waving), yielding characteristic reaction rate constants. It appears that DSC in water is an especially suitable method to determine the kinetics of damage formation in human hair resulting from cosmetic treatments.

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

    Science.gov (United States)

    Mårtensson, Anna K F; Lincoln, Per

    2015-02-28

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

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

    Science.gov (United States)

    Johnson, William L.

    2000-01-01

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

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

    Science.gov (United States)

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

    2012-09-01

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

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

    Science.gov (United States)

    Pethica, Brian A

    2015-03-01

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

  15. Analysis of IgG kinetic stability by differential scanning calorimetry, probe fluorescence and light scattering.

    Science.gov (United States)

    Nemergut, Michal; Žoldák, Gabriel; Schaefer, Jonas V; Kast, Florian; Miškovský, Pavol; Plückthun, Andreas; Sedlák, Erik

    2017-08-19

    Monoclonal antibodies of the immunoglobulin G (IgG) type have become mainstream therapeutics for the treatment of many life-threatening diseases. For their successful application in the clinic and a favorable cost-benefit ratio, the design and formulation of these therapeutic molecules must guarantee long-term stability for an extended period of time. Accelerated stability studies, e.g., by employing thermal denaturation, have the great potential for enabling high-throughput screening campaigns to find optimal molecular variants and formulations in a short time. Surprisingly, no validated quantitative analysis of these accelerated studies has been performed yet, which clearly limits their application for predicting IgG stability. Therefore, we have established a quantitative approach for the assessment of the kinetic stability over a broad range of temperatures. To this end, differential scanning calorimetry (DSC) experiments were performed with a model IgG, testing chaotropic formulations and an extended temperature range, and they were subsequently analyzed by our recently developed three-step sequential model of IgG denaturation, consisting of one reversible and two irreversible steps. A critical comparison of the predictions from this model with data obtained by an orthogonal fluorescence probe method, based on 8-anilinonaphthalene-1-sulfonate binding to partially unfolded states, resulted in very good agreement. In summary, our study highlights the validity of this easy-to-perform analysis for reliably assessing the kinetic stability of IgGs, which can support accelerated formulation development of monoclonal antibodies by ranking different formulations as well as by improving colloidal stability models. © 2017 The Protein Society.

  16. Use of differential scanning calorimetry to detect canola oil (Brassica napus L.) adulterated with lard stearin.

    Science.gov (United States)

    Marikkar, Jalaldeen Mohammed Nazrim; Rana, Sohel

    2014-01-01

    A study was conducted to detect and quantify lard stearin (LS) content in canola oil (CaO) using differential scanning calorimetry (DSC). Authentic samples of CaO were obtained from a reliable supplier and the adulterant LS were obtained through a fractional crystallization procedure as reported previously. Pure CaO samples spiked with LS in levels ranging from 5 to 15% (w/w) were analyzed using DSC to obtain their cooling and heating profiles. The results showed that samples contaminated with LS at 5% (w/w) level can be detected using characteristic contaminant peaks appearing in the higher temperature regions (0 to 70°C) of the cooling and heating curves. Pearson correlation analysis of LS content against individual DSC parameters of the adulterant peak namely peak temperature, peak area, peak onset temperature indicated that there were strong correlations between these with the LS content of the CaO admixtures. When these three parameters were engaged as variables in the execution of the stepwise regression procedure, predictive models for determination of LS content in CaO were obtained. The predictive models obtained with single DSC parameter had relatively lower coefficient of determination (R(2) value) and higher standard error than the models obtained using two DSC parameters in combination. This study concluded that the predictive models obtained with peak area and peak onset temperature of the adulteration peak would be more accurate for prediction of LS content in CaO based on the highest coefficient of determination (R(2) value) and smallest standard error.

  17. Collecting Variable-concentration Isothermal Titration Calorimetry Datasets in Order to Determine Binding Mechanisms

    Science.gov (United States)

    Freiburger, Lee A.; Mittermaier, Anthony K.; Auclair, Karine

    2011-01-01

    Isothermal titration calorimetry (ITC) is commonly used to determine the thermodynamic parameters associated with the binding of a ligand to a host macromolecule. ITC has some advantages over common spectroscopic approaches for studying host/ligand interactions. For example, the heat released or absorbed when the two components interact is directly measured and does not require any exogenous reporters. Thus the binding enthalpy and the association constant (Ka) are directly obtained from ITC data, and can be used to compute the entropic contribution. Moreover, the shape of the isotherm is dependent on the c-value and the mechanistic model involved. The c-value is defined as c = n[P]tKa, where [P]t is the protein concentration, and n is the number of ligand binding sites within the host. In many cases, multiple binding sites for a given ligand are non-equivalent and ITC allows the characterization of the thermodynamic binding parameters for each individual binding site. This however requires that the correct binding model be used. This choice can be problematic if different models can fit the same experimental data. We have previously shown that this problem can be circumvented by performing experiments at several c-values. The multiple isotherms obtained at different c-values are fit simultaneously to separate models. The correct model is next identified based on the goodness of fit across the entire variable-c dataset. This process is applied here to the aminoglycoside resistance-causing enzyme aminoglycoside N-6'-acetyltransferase-Ii (AAC(6')-Ii). Although our methodology is applicable to any system, the necessity of this strategy is better demonstrated with a macromolecule-ligand system showing allostery or cooperativity, and when different binding models provide essentially identical fits to the same data. To our knowledge, there are no such systems commercially available. AAC(6')-Ii, is a homo-dimer containing two active sites, showing cooperativity between

  18. Collecting variable-concentration isothermal titration calorimetry datasets in order to determine binding mechanisms.

    Science.gov (United States)

    Freiburger, Lee A; Mittermaier, Anthony K; Auclair, Karine

    2011-04-07

    Isothermal titration calorimetry (ITC) is commonly used to determine the thermodynamic parameters associated with the binding of a ligand to a host macromolecule. ITC has some advantages over common spectroscopic approaches for studying host/ligand interactions. For example, the heat released or absorbed when the two components interact is directly measured and does not require any exogenous reporters. Thus the binding enthalpy and the association constant (Ka) are directly obtained from ITC data, and can be used to compute the entropic contribution. Moreover, the shape of the isotherm is dependent on the c-value and the mechanistic model involved. The c-value is defined as c = n[P]tKa, where [P]t is the protein concentration, and n is the number of ligand binding sites within the host. In many cases, multiple binding sites for a given ligand are non-equivalent and ITC allows the characterization of the thermodynamic binding parameters for each individual binding site. This however requires that the correct binding model be used. This choice can be problematic if different models can fit the same experimental data. We have previously shown that this problem can be circumvented by performing experiments at several c-values. The multiple isotherms obtained at different c-values are fit simultaneously to separate models. The correct model is next identified based on the goodness of fit across the entire variable-c dataset. This process is applied here to the aminoglycoside resistance-causing enzyme aminoglycoside N-6'-acetyltransferase-Ii (AAC(6')-Ii). Although our methodology is applicable to any system, the necessity of this strategy is better demonstrated with a macromolecule-ligand system showing allostery or cooperativity, and when different binding models provide essentially identical fits to the same data. To our knowledge, there are no such systems commercially available. AAC(6')-Ii, is a homo-dimer containing two active sites, showing cooperativity between

  19. DSC、MDSC测定物质比热容的比较%Comparison of differential scanning calorimetry and modulated differential scanning calorimetry in measurement of specific heat capacities

    Institute of Scientific and Technical Information of China (English)

    鲁红; 冯大春; 杨继佑

    2011-01-01

    实验用TA公司具有DSC、MDSC两种模式、具备先进Tzero技术的热流型DSCQ200热分析仪测定物质的比热容.对如何运用传统方法及调制方法测定物质的比热容进行了详细阐述;以氯化钾、苯甲酸、去离子水为测试样,对两种方法所得实验结果进行了分析比较.%The specific heat capacities of potassium choride, benzoic acid and deionized water samples were measured by DSCQ 200 tbermal analyzer in two different method (differential scanning calorimetry. DSC, and modulated differential scanning calorimetry. MDSC), The results obtained by two methods are compared.The questions in the application of DSC and MDSC are discussed in detail.

  20. Determination of heat transfer coefficients at the polymer-mold-interface for injection molding simulation by means of calorimetry

    Science.gov (United States)

    Stricker, M.; Steinbichler, G.

    2014-05-01

    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.

  1. Synthesis kinetics of Mg_2Sn in Mg-Sn powder mixture using non-isothermal differential scanning calorimetry

    Institute of Scientific and Technical Information of China (English)

    WU Yu-feng; DU Wen-bo; ZUO Tie-yong

    2009-01-01

    The non-isothermal heating process of Mg-Sn powder mixture was studied by differential scanning calorimetry(DSC) technique and the synthesis kinetics of Mg_2Sn was evaluated by the model-free and model-fitting methods. The activation energy and conversion function of Mg_2Sn synthesis reaction are calculated to be 281.7 kJ/mol and g(α)=[-ln(1-α)]~(1/4), respectively. The reaction mechanism of 2Mg+Sn→Mg_2Sn under non-isothermal condition is regarded as "nucleation and growth". During the non-isothermal heating process, the phase transformation occurred in the Mg-Sn powder mixture was analyzed by XRD and the microstructure evolution of Mg_2Sn was observed by optical microscopy, which is in good agreement with the reaction mechanism of 2Mg+Sn→Mg_2Sn deduced from the kinetic evaluation.

  2. Conductivity, calorimetry and phase diagram of the NaHSO4–KHSO4 system

    DEFF Research Database (Denmark)

    Hind, Hamma-Cugny; Rasmussen, Søren Birk; Rogez, J.

    2006-01-01

    Physico-chemical properties of the binary system NaHSO4-KHSO4 were studied by calorimetry and conductivity, The enthalpy of mixing has been measured at 505 K in the full composition range and the phase diagram calculated. The phase diagram has also been constructed from phase transition temperatu......Physico-chemical properties of the binary system NaHSO4-KHSO4 were studied by calorimetry and conductivity, The enthalpy of mixing has been measured at 505 K in the full composition range and the phase diagram calculated. The phase diagram has also been constructed from phase transition...

  3. Monitoring of an RNA Multistep Folding Pathway by Isothermal Titration Calorimetry

    Science.gov (United States)

    Reymond, Cédric; Bisaillon, Martin; Perreault, Jean-Pierre

    2009-01-01

    Abstract Isothermal titration calorimetry was used to monitor the energetic landscape of a catalytic RNA, specifically that of the hepatitis delta virus ribozyme. Using mutants that isolated various tertiary interactions, the thermodynamic parameters of several ribozyme-substrate intermediates were determined. The results shed light on the impact of several tertiary interactions on the global structure of the ribozyme. In addition, the data indicate that the formation of the P1.1 pseudoknot is the limiting step of the molecular mechanism. Last, as illustrated here, isothermal titration calorimetry appears to be a method of choice for the elucidation of an RNA's folding pathway. PMID:19134473

  4. Insights into glass transition and relaxation behavior using temperature-modulated differential scanning calorimetry

    DEFF Research Database (Denmark)

    Guo, Xiaoju; Mauro, J.C.; Allan, D.C.;

    Temperature-modulated differential scanning calorimetry (TMDSC) is based on conventional DSC but with a sinusoidally modulated temperature path. Our simulations of TMDSC signals prove that the frequency correction of non-reversing heat flow can give a master curve within a certain range of freque......Temperature-modulated differential scanning calorimetry (TMDSC) is based on conventional DSC but with a sinusoidally modulated temperature path. Our simulations of TMDSC signals prove that the frequency correction of non-reversing heat flow can give a master curve within a certain range...

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

    Science.gov (United States)

    Henzl, Michael T

    2009-01-01

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

  6. Differential scanning calorimetry predicts the critical quality attributes of amorphous glibenclamide.

    Science.gov (United States)

    Mah, Pei T; Laaksonen, Timo; Rades, Thomas; Peltonen, Leena; Strachan, Clare J

    2015-12-01

    Selection of a crystallinity detection tool that is able to predict the critical quality attributes of amorphous formulations is imperative for the development of process control strategies. The main aim of this study was to determine the crystallinity detection tool that best predicts the critical quality attributes (i.e. physical stability and dissolution behaviour) of amorphous material. Glibenclamide (model drug) was milled for various durations using a planetary mill and characterised using Raman spectroscopy and differential scanning calorimetry (DSC). Physical stability studies upon storage at 60°C/0% RH and dissolution studies (non-sink conditions) were performed on the milled glibenclamide samples. Different milling durations were needed to render glibenclamide fully amorphous according to Raman spectroscopy (60min) and onset of crystallisation using DSC (150min). This could be due to the superiority of DSC (onset of crystallisation) in detecting residual crystallinity in the samples milled for between 60 and 120min, which were not detectable with Raman spectroscopy. The physical stability upon storage and dissolution behaviour of the milled samples improved with increased milling duration and plateaus were reached after milling for certain periods of time (physical stability - 150min; dissolution - 120min). The residual crystallinity which was detectable with DSC (onset of crystallisation), but not with Raman spectroscopy, adversely affected the critical quality attributes of milled glibenclamide samples. In addition, mathematical simulations were performed on the dissolution data to determine the solubility advantages of the milled glibenclamide samples and to describe the crystallisation process that occurred during dissolution in pH7.4 phosphate buffer. In conclusion, the onset of crystallisation obtained from DSC measurements best predicts the critical quality attributes of milled glibenclamide samples and mathematical simulations based on the

  7. Estimation of the nucleation rate by differential scanning calorimetry

    Science.gov (United States)

    Kelton, Kenneth F.

    1992-01-01

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

  8. Estimation of the nucleation rate by differential scanning calorimetry

    Science.gov (United States)

    Kelton, Kenneth F.

    1992-01-01

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

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

    Science.gov (United States)

    Akchurin, Nural

    2012-12-01

    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

  10. Investigation of Phase Mixing in Amorphous Solid Dispersions of AMG 517 in HPMC-AS Using DSC, Solid-State NMR, and Solution Calorimetry.

    Science.gov (United States)

    Calahan, Julie L; Azali, Stephanie C; Munson, Eric J; Nagapudi, Karthik

    2015-11-02

    Intimate phase mixing between the drug and the polymer is considered a prerequisite to achieve good physical stability for amorphous solid dispersions. In this article, spray dried amorphous dispersions (ASDs) of AMG 517 and HPMC-as were studied by differential scanning calorimetry (DSC), solid-state NMR (SSNMR), and solution calorimetry. DSC analysis showed a weakly asymmetric (ΔTg ≈ 13.5) system with a single glass transition for blends of different compositions indicating phase mixing. The Tg-composition data was modeled using the BKCV equation to accommodate the observed negative deviation from ideality. Proton spin-lattice relaxation times in the laboratory and rotating frames ((1)H T1 and T1ρ), as measured by SSNMR, were consistent with the observation that the components of the dispersion were in intimate contact over a 10-20 nm length scale. Based on the heat of mixing calculated from solution calorimetry and the entropy of mixing calculated from the Flory-Huggins theory, the free energy of mixing was calculated. The free energy of mixing was found to be positive for all ASDs, indicating that the drug and polymer are thermodynamically predisposed to phase separation at 25 °C. This suggests that miscibility measured by DSC and SSNMR is achieved kinetically as the result of intimate mixing between drug and polymer during the spray drying process. This kinetic phase mixing is responsible for the physical stability of the ASD.

  11. The effect of increasing membrane curvature on the phase transition and mixing behavior of a dimyristoyl-sn-glycero-3-phosphatidylcholine/distearoyl-sn-glycero-3-phosphatidylcholine lipid mixture as studied by Fourier transform infrared spectroscopy and differential scanning calorimetry

    DEFF Research Database (Denmark)

    Brumm, T.; Jørgensen, Kent; Mouritsen, Ole G.

    1996-01-01

    The phase transition behavior of a lipid bilayer of dimyristoyl-sn-glycero-3-phosphalidylcholine/distearoyl-sn- glycero-3-phosphatidylcholine (DMPC-d54/DSPC) (1:1) on a solid support with varying curvatures was investigated with differential scanning calorimetry, infrared spectroscopy, and model...

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

    Science.gov (United States)

    Tellinghuisen, Joel

    2012-05-15

    Literature recommendations for designing isothermal titration calorimetry (ITC) experiments to study 1:1 binding, M+X -->/applicability of the ITC technique. These deficiencies are discussed here along with other misconceptions. Whether a specific binding process can be studied by ITC is determined less by c (the product of binding constant K and titrand concentration [M](0)) than by the total detectable heat q(tot) and the extent to which M can be converted to MX. As guidelines, with 90% conversion to MX, K can be estimated within 5% over the range 10 to 10(8)M(-1) when q(tot)/σ(q)≈700, where σ(q) is the standard deviation for estimation of q. This ratio drops to ~150 when the stoichiometry parameter n is treated as known. A computer application for modeling 1:1 binding yields realistic estimates of parameter standard errors for use in protocol design and feasibility assessment.

  13. Interaction of Ru(Ⅱ) Complex with Yeast tRNA Studied by Isothermal Titration Calorimetry

    Institute of Scientific and Technical Information of China (English)

    徐宏; 刘敛洪; 刘志刚; 梁毅; 张鹏; 杜芬; 周兵瑞; 计亮年

    2005-01-01

    The interaction of metal complex with RNA has been studied by isothermal titration calorimetry (ITC) for the first time. ITC experiments show that complex [Ru(phen)2MPIP]2+ {phen= 1,10-phenanthroline, MP[P-2-(4-methylphenyl)imidazo[4,5-f]-1, 10-phenanthroline} interacts with yeast tRNA in terms of a model for a singleset of identical sites through intercalation, which is consistent with our previous observation obtained from spectroscopic methods, and this binding process was driven by a moderately favorable enthalpy decrease in combination with a moderately favorable entropy increase, suggesting that ITC is an effective method for deep studying the interactions of metal complexes with RNA.

  14. Prediction of VO2max from a new field test based on portable indirect calorimetry.

    Science.gov (United States)

    Flouris, Andreas D; Metsios, Giorgos S; Famisis, Konstantinos; Geladas, Nikos; Koutedakis, Yiannis

    2010-01-01

    We assessed the validity and reliability of the new 15m square shuttle run test (SST) for predicting laboratory treadmill test (TT) maximal oxygen uptake (VO(2 max)) compared to the 20 m multistage shuttle run test (MST) in 45 adult males. Thirty participants performed a TT and a SST once to develop a VO( 2max) prediction model. The remaining 15 participants performed the TT and MST once and the SST twice for cross-validation purposes. Throughout testing V O(2max) was determined via portable indirect calorimetry while blood lactate concentration was assessed at the fifth recovery minute. Comparisons of TT V O(2 max) (51.3+/-3.1 ml kg(-1)min(-1)) with SST measured (51.2+/-3.2 ml kg(-1)min(-1)) and predicted (50.9+/-3.3 ml kg(-1)min(-1)) V O(2 max) showed no differences while TT blood lactate was higher compared to SST (10.3+/-1.7 mmol vs. 9.7+/-1.7 mmol, respectively). In contrast, MST measured (53.4+/-3.5 ml kg(-1)min(-1)) and predicted (57.0+/-4.5 ml kg(-1)min(-1)) V O(2 max) and blood lactate (11.2+/-2.0 mmol) were significantly higher compared to TT. No test-retest differences were detected for SST measured and predicted V O(2 max) and blood lactate. It is concluded that the SST is a highly valid and reliable predictive test for V O(2 max). Copyright (c) 2009 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  15. Digital holographic interferometry: a novel optical calorimetry technique for radiation dosimetry.

    Science.gov (United States)

    Cavan, Alicia; Meyer, Juergen

    2014-02-01

    To develop and demonstrate the proof-of-principle of a novel optical calorimetry method to determine radiation absorbed dose in a transparent medium. 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. 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(-4) K). The relative dose fall off was in agreement with treatment planning system modeled data. 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(-4) 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.

  16. Use of isothermal titration calorimetry to study surfactant aggregation in colloidal systems.

    Science.gov (United States)

    Loh, Watson; Brinatti, César; Tam, Kam Chiu

    2016-05-01

    Isothermal titration calorimetry (ITC) is a general technique that allows for precise and highly sensitive measurements. These measurements may provide a complete and accurate thermodynamic description of association processes in complex systems such as colloidal mixtures. This review will address uses of ITC for studies of surfactant aggregation to form micelles, with emphasis on the thermodynamic studies of homologous surfactant series. We will also review studies on surfactant association with polymers of different molecular characteristics and with colloidal particles. ITC studies on the association of different homologous series of surfactants provide quantitative information on independent contribution from their apolar hydrocarbon chains and polar headgroups to the different thermodynamic functions associated with micellization (Gibbs energy, enthalpy and entropy). Studies on surfactant association to polymers by ITC provide a comprehensive description of the association process, including examples in which particular features revealed by ITC were elucidated by using ancillary techniques such as light or X-ray scattering measurements. Examples of uses of ITC to follow surfactant association to biomolecules such as proteins or DNA, or nanoparticles are also highlighted. Finally, recent theoretical models that were proposed to analyze ITC data in terms of binding/association processes are discussed. This review stresses the importance of using direct calorimetric measurements to obtain and report accurate thermodynamic data, even in complex systems. These data, whenever possible, should be confirmed and associated with other ancillary techniques that allow elucidation of the nature of the transformations detected by calorimetric results, providing a complete description of the process under scrutiny. Copyright © 2015 Elsevier B.V. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

    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); 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)

    2014-02-15

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

  18. Phase behavior in the system tetrahydrofuran-water-ammonia from calorimetry and Raman spectroscopy

    Science.gov (United States)

    Munoz-Iglesias, Victoria; Vu, Tuan; Choukroun, Mathieu; Hodyss, Robert; Smythe, William; Sotin, Christophe

    2016-10-01

    From geochemical models and Cassini-Huygens mission data it can be postulated that the icy crust of Titan is composed by water ice, clathrate hydrates and ammonia hydrates. When the shell evolves thermically, the first minerals in dissociating are the ammonia hydrates. Ammonia is a powerful antifreeze, promoting the drop of the equilibrium curves of both water ice and clathrates to values as low as 170 K and 203 K respectively. Calorimetry, using a Setaram BT 2.15 Calvet calorimeter, has allowed to identify the different phases formed in the system THF-H2O-NH3 when the molar ratio H2O:THF is 1:X 17, which corresponds with the THF-clathrate stoichiometric ratio, and at NH3 concentrations up to 30 wt%. When X 17, the H2O is in excess; the formation of ammonia hydrates, water ice and THF-clathrate is observed. Since under this condition, all available THF is trapped in the clathrate, no THF-NH3 phase is observed. In all the scenarios, the release of NH3 (from the melting of THF-NH3 solid or ammonia hydrates) promotes partial dissociation of THF clathrates, which start at much lower temperature the equilibrium dissociation of the clathrates. This research is supported by an appointment to the NASA Postdoctoral Program at the Jet Propulsion Laboratory, California Institute of Technology, administered by Universities Space Research Association (USRA) through a contract with NASA. Support from the NASA Outer Planets Research program and government sponsorship acknowledged.

  19. Calorimetry and thermodynamic aspects of heterotrophic, mixotrophic, and phototrophic growth

    NARCIS (Netherlands)

    Stockar, von U.; Marison, I.; Janssen, M.G.J.; Patino, R.

    2011-01-01

    A simple stoichiometric model is proposed linking the biomass yield to the enthalpy and Gibbs energy changes in chemo-heterotrophic, mixotrophic, and photo-autotrophic microbial growth. A comparison with calorimetric experiments on the algae Chlorella vulgaris and Chlorella sorokiniana confirmed the

  20. Calorimetry and thermodynamic aspects of heterotrophic, mixotrophic, and phototrophic growth

    NARCIS (Netherlands)

    Stockar, von U.; Marison, I.; Janssen, M.G.J.; Patino, R.

    2011-01-01

    A simple stoichiometric model is proposed linking the biomass yield to the enthalpy and Gibbs energy changes in chemo-heterotrophic, mixotrophic, and photo-autotrophic microbial growth. A comparison with calorimetric experiments on the algae Chlorella vulgaris and Chlorella sorokiniana confirmed the

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

    Science.gov (United States)

    Bhadra, Kakali; Kumar, Gopinatha Suresh

    2010-11-01

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

  2. Determination of ice content in hardened concrete by low-temperature calorimetry

    DEFF Research Database (Denmark)

    Wu, Min; Johannesson, Björn; Geiker, Mette Rica

    2014-01-01

    Low-temperature calorimetry has been used to determine the ice content in concrete at different temperatures when exposed to low-temperature environments. However, the analysis of the ice content from the measured data of heat flow is not straightforward. In this study, two important factors...

  3. Isothermal Titration Calorimetry and Macromolecular Visualization for the Interaction of Lysozyme and Its Inhibitors

    Science.gov (United States)

    Wei, Chin-Chuan; Jensen, Drake; Boyle, Tiffany; O'Brien, Leah C.; De Meo, Cristina; Shabestary, Nahid; Eder, Douglas J.

    2015-01-01

    To provide a research-like experience to upper-division undergraduate students in a biochemistry teaching laboratory, isothermal titration calorimetry (ITC) is employed to determine the binding constants of lysozyme and its inhibitors, N-acetyl glucosamine trimer (NAG[subscript 3]) and monomer (NAG). The extremely weak binding of lysozyme/NAG is…

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

    Science.gov (United States)

    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...

  5. Partitioning of late gestation energy expenditure in ewes using indirect calorimetry and a linear regression approach

    DEFF Research Database (Denmark)

    Kiani, Alishir; Chwalibog, André; Nielsen, Mette O

    2007-01-01

    study metabolizable energy (ME) intake ranges for twin-bearing ewes were 220-440, 350- 700, 350-900 kJ per metabolic body weight (W0.75) at week seven, five, two pre-partum respectively. Indirect calorimetry and a linear regression approach were used to quantify EE(gest) and then partition to EE...

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

    Science.gov (United States)

    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...

  7. Thermoreversible gelation of cellulose acetate solutions studied by differential scanning calorimetry

    NARCIS (Netherlands)

    Altena, F.W.; Schroder, J.S.; Huls, van de R.; Smolders, C.A.

    1986-01-01

    Thermoreversible gels of cellulose acetate can be obtained by cooling concentrated cellulose acetate solutions in solvent-nonsolvent mixtures of dioxane and water. Upon heating the gels, endothermic effects were observed with differential scanning calorimetry. The heat effects are ascribed to the me

  8. Thermodynamic profiling of Peptide membrane interactions by isothermal titration calorimetry: a search for pores and micelles

    DEFF Research Database (Denmark)

    Henriksen, Jonas Rosager; Andresen, Thomas Lars

    2011-01-01

    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...

  9. Isothermal Titration Calorimetry and Macromolecular Visualization for the Interaction of Lysozyme and Its Inhibitors

    Science.gov (United States)

    Wei, Chin-Chuan; Jensen, Drake; Boyle, Tiffany; O'Brien, Leah C.; De Meo, Cristina; Shabestary, Nahid; Eder, Douglas J.

    2015-01-01

    To provide a research-like experience to upper-division undergraduate students in a biochemistry teaching laboratory, isothermal titration calorimetry (ITC) is employed to determine the binding constants of lysozyme and its inhibitors, N-acetyl glucosamine trimer (NAG[subscript 3]) and monomer (NAG). The extremely weak binding of lysozyme/NAG is…

  10. Aqueous solutions of proline and NaCl studied by differential scanning calorimetry at subzero temperatures

    DEFF Research Database (Denmark)

    Rasmussen, Peter Have; Jørgensen, Bo; Nielsen, Jette

    1997-01-01

    The hydration properties of proline are studied by differential scanning calorimetry (DSC) in aqueous solutions during freezing to -60 degrees C and subsequent heating to +20 degrees C. The concentration of proline in the freeze concentrated solution was estimated to approximately 50 wt% (w/w) in...

  11. On the Frequency Correction in Temperature-Modulated Differential Scanning Calorimetry of Glass Transition

    DEFF Research Database (Denmark)

    Guo, Xiaoju; Mauro, J.C.; Allan, D.C.;

    2012-01-01

    Temperature-modulated differential scanning calorimetry (TMDSC) is based on conventional DSC but with a sinusoidally modulated temperature path. Simulations of TMDSC signals were performed for Corning EAGLE XG® glass over a wide range of modulation frequencies. Our results reveal that the frequen...

  12. Low-temperature transitions in cod and tuna determined by differential scanning calorimetry

    DEFF Research Database (Denmark)

    Jensen, Kristina Nedenskov; Jørgensen, Bo; Nielsen, Jette

    2003-01-01

    Differential scanning calorimetry measurements have revealed different thermal transitions in cod and tuna samples. Transition temperatures detected Lit -11degreesC, -15degreesC and -21degreesC were highly dependent on the annealing temperature. In tuna muscle an additional transition was observe...

  13. Levitation calorimetry. IV - The thermodynamic properties of liquid cobalt and palladium.

    Science.gov (United States)

    Treverton, J. A.; Margrave, J. L.

    1971-01-01

    Some of the thermodynamic properties of liquid cobalt and palladium investigated by means of levitation calorimetry are reported and discussed. The presented data include the specific heats and heats of fusion of the liquid metals, and the emissivities of the liquid metal surfaces.

  14. Student Learning of Thermochemical Concepts in the Context of Solution Calorimetry.

    Science.gov (United States)

    Greenbowe, Thomas J.; Meltzer, David E.

    2003-01-01

    Analyzes student performance on solution calorimetry problems in an introductory university chemistry class. Includes data from written classroom exams for 207 students and an extensive longitudinal interview with a student. Indicates learning difficulties, most of which appear to originate from failure to understand, that net increases and…

  15. Gamma Polari-Calorimetry with SOI pixels for proposals at Extreme Light Infrastructure (ELI-NP)

    CERN Document Server

    Homma, Kensuke

    2015-01-01

    We introduce the concept of Gamma Polari-Calorimetry (GPC) dedicated for proposals at Extreme Light Infrastructure in the Romanian site (ELI-NP). A simulation study shows that an assembly of thin SOI pixel sensors can satisfy our requirements to GPC.

  16. Insights into glass transition and relaxation behavior using temperature-modulated differential scanning calorimetry

    DEFF Research Database (Denmark)

    Guo, Xiaoju; Mauro, J.C.; Allan, D.C.

    Temperature-modulated differential scanning calorimetry (TMDSC) is based on conventional DSC but with a sinusoidally modulated temperature path. Our simulations of TMDSC signals prove that the frequency correction of non-reversing heat flow can give a master curve within a certain range...

  17. Thermoreversible gelation of cellulose acetate solutions studied by differential scanning calorimetry

    NARCIS (Netherlands)

    Altena, F.W.; Schroder, J.S.; van de Huls, R.; Smolders, C.A.

    1986-01-01

    Thermoreversible gels of cellulose acetate can be obtained by cooling concentrated cellulose acetate solutions in solvent-nonsolvent mixtures of dioxane and water. Upon heating the gels, endothermic effects were observed with differential scanning calorimetry. The heat effects are ascribed to the

  18. Examination of water phase transitions in Loblolly pine and cell wall components by differential scanning calorimetry

    Science.gov (United States)

    Samuel L. Zelinka; Michael J. Lambrecht; Samuel V. Glass; Alex C. Wiedenhoeft; Daniel J. Yelle

    2012-01-01

    This paper examines phase transformations of water in wood and isolated wood cell wall components using differential scanning calorimetry with the purpose of better understanding "Type II water" or "freezable bound water" that has been reported for cellulose and other hydrophilic polymers. Solid loblolly pine (Pinus taeda...

  19. Low-temperature transitions in cod and tuna determined by differential scanning calorimetry

    DEFF Research Database (Denmark)

    Jensen, Kristina Nedenskov; Jørgensen, Bo; Nielsen, Jette

    2003-01-01

    Differential scanning calorimetry measurements have revealed different thermal transitions in cod and tuna samples. Transition temperatures detected Lit -11degreesC, -15degreesC and -21degreesC were highly dependent on the annealing temperature. In tuna muscle an additional transition was observed...

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

    Science.gov (United States)

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

    2005-01-01

    A comprehensive theoretical description of thermal protein unfolding coupled to ligand binding is presented. The thermodynamic concepts are independent of the method used to monitor protein unfolding but a differential scanning calorimetry is being used as a tool for examining the unfolding process.

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

    Science.gov (United States)

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

    2011-06-20

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

  2. Calorimetry of the JET ITER-Like Wall components

    Energy Technology Data Exchange (ETDEWEB)

    Devaux, S., E-mail: stephane.devaux@ccfe.ac.uk [Max-Planck-Institut für Plasmaphysik, EURATOM-Assoziation, D-85748 Garching (Germany); Arnoux, G. [EURATOM/CCFE Association, Culham Science Center, Abingdon, Oxon OX14 3DB (United Kingdom); Corre, Y. [Association EURTATOM-CEA, CEA/DSM/IRFM, Cadarache, 13108 Saint Paul lez Durance (France); Gardarein, J-L.; Gaspar, J. [IUSTI UMR CNRS 7343, Aix-Marseille University Marseille (France); Jacquet, P. [Max-Planck-Institut für Plasmaphysik, EURATOM-Assoziation, D-85748 Garching (Germany); Marcotte, F. [EURATOM/CCFE Association, Culham Science Center, Abingdon, Oxon OX14 3DB (United Kingdom); Matthews, G.; Beaumont, P.; Cramp, S.; Dalley, S.; Kinna, D.; Horton, A.; Lomas, P. [Max-Planck-Institut für Plasmaphysik, EURATOM-Assoziation, D-85748 Garching (Germany); Mertens, Ph. [Institute of Energy and Climate Research IEK-4 (Plasma Physics), Forschungszentrum Jülich GmbH, Association EURATOM-FZJ, D-52425 Jülich (Germany); Riccardo, V. [Max-Planck-Institut für Plasmaphysik, EURATOM-Assoziation, D-85748 Garching (Germany); Valcàrcel, D. [Associação EURATOM/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade Técnica de Lisboa, P-1049-001 Lisboa (Portugal)

    2013-07-15

    As part of the ILW project, new diagnostics have been installed in order to protect the plasma-facing components (PFCs). Here we present the diagnostics used to monitor the PFC temperature, thermocouples and cameras, and assess the consistency of their measurements. In dedicated limited L-mode plasmas, the surface of the limiter tiles are heated up to 900 °C. The comparison of surface temperature measurements from IR and near IR cameras, which have been calibrated against a black-body source, leads to a Be emissivity of 0.18, comparable with the theoretical one. Energy calculation derived from thermocouples, which are embedded in both limiters and divertor target plates (W-coated CFC), is compared to a 1D model based on thermal quadrupole approach (benchmarked with an ANSYS model) associated to an inversion computation. The analysis of 20 pulses shows that a good energy balance is achieved within the error bar of the model, assessed to be of 30%.

  3. Isothermal titration calorimetry in nanoliter droplets with subsecond time constants.

    Science.gov (United States)

    Lubbers, Brad; Baudenbacher, Franz

    2011-10-15

    We reduced the reaction volume in microfabricated suspended-membrane titration calorimeters to nanoliter droplets and improved the sensitivities to below a nanowatt with time constants of around 100 ms. The device performance was characterized using exothermic acid-base neutralizations and a detailed numerical model. The finite element based numerical model allowed us to determine the sensitivities within 1% and the temporal dynamics of the temperature rise in neutralization reactions as a function of droplet size. The model was used to determine the optimum calorimeter design (membrane size and thickness, junction area, and thermopile thickness) and sensitivities for sample volumes of 1 nL for silicon nitride and polymer membranes. We obtained a maximum sensitivity of 153 pW/(Hz)(1/2) for a 1 μm SiN membrane and 79 pW/(Hz)(1/2) for a 1 μm polymer membrane. The time constant of the calorimeter system was determined experimentally using a pulsed laser to increase the temperature of nanoliter sample volumes. For a 2.5 nanoliter sample volume, we experimentally determined a noise equivalent power of 500 pW/(Hz)(1/2) and a 1/e time constant of 110 ms for a modified commercially available infrared sensor with a thin-film thermopile. Furthermore, we demonstrated detection of 1.4 nJ reaction energies from injection of 25 pL of 1 mM HCl into a 2.5 nL droplet of 1 mM NaOH.

  4. The colligative properties of fruit juices by photopyroelectric calorimetry

    Science.gov (United States)

    Frandas, A.; Surducan, V.; Nagy, G.; Bicanic, D.

    1999-03-01

    The photopyroelectric method was used to study the depression of freezing point in juices prepared from selected apple and orange juice concentrates. By using the models for real solutions, the effective molecular weight of the dissolved solids was obtained. The acids concentration in the fruit juice is reflected both in the equivalent molecular weight (by lowering it) and in the interaction coefficients b and C. Using the data for the molecular weight and the characteristic coefficients, prediction curves for the samples investigated can be used in practice. Freezing point depression can also be used as an indicator of the degree of spoilage of fruit juices.

  5. Elucidating thermodynamic parameters for electron transfer proteins using isothermal titration calorimetry: application to the nitrogenase Fe protein.

    Science.gov (United States)

    Sørlie, Morten; Chan, Jeannine M; Wang, Haijang; Seefeldt, Lance C; Parker, Vernon D

    2003-05-01

    Establishing thermodynamic parameters for electron transfer reactions involving redox proteins is essential for a complete description of these important reactions. While various methods have been developed for measuring the Gibbs free energy change (Delta G(HR) or E(m)) for the protein half-reactions, deconvolution of the respective contributions of enthalpy (Delta H(HR)) and entropy (Delta S(HR)) changes is much more challenging. In the present work, an approach is developed using isothermal titration calorimetry (ITC) that allows accurate determination of all of these thermodynamic parameters for protein electron transfer half-reactions. The approach was validated for essentially irreversible and reversible electron transfer reactions between well-characterized mediators and between mediators and the protein cytochrome c. In all cases, the measured thermodynamic parameters were in excellent agreement with parameters determined by electrochemical methods. Finally, the calorimetry approach was used to determine thermodynamic parameters for electron transfer reactions of the nitrogenase Fe protein [4Fe-4S](2+/+) couple in the absence or presence of MgADP or MgATP. The E(m) value was found to change from -290 mV in the absence of nucleotides to -381 mV with MgATP and -423 mV with MgADP, consistent with earlier values. For the first time, the enthalpy (Delta H(HR)) and entropy (Delta S(HR)) contributions for each case were established, revealing shifts in the contribution of each thermodynamic parameter induced by nucleotide binding. The results are discussed in the context of current models for electron transfer in nitrogenase.

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

    Science.gov (United States)

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

    2012-01-01

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

  7. Insights into the binding of the drugs diclofenac sodium and cefotaxime sodium to serum albumin: calorimetry and spectroscopy.

    Science.gov (United States)

    Sharma, Ruchika; Choudhary, Sinjan; Kishore, Nand

    2012-08-15

    Understanding physical chemistry underlying drug-protein interactions is essential to devise guidelines for the synthesis of target oriented drugs. Binding of a non-steroidal anti-inflammatory drug, diclofenac sodium (DCF) and an antibiotic drug, cefotaxime sodium (CFT) belonging to the family of cephalosporins with bovine serum albumin (BSA) has been examined using a combination of isothermal titration calorimetry (ITC), differential scanning calorimetry (DSC), steady state and time resolved fluorescence and circular dichroism spectroscopies. Binding affinity of both DCF and CFT with BSA is observed to be of the order of 10(4)M(-1), with the binding profiles fitting well to the single set of binding site model. The disagreement between calorimetric and van't Hoff enthalpies indicates non-adherence to a two-state binding process which could be attributed to changes in the conformation of the protein upon ligand binding as well as with increase in the temperature. Circular dichroism and the fluorescence results, however, do not show any major conformational changes upon binding of these drugs to BSA, and hence the discrepancy could be due to temperature induced conformational changes in the protein. The results of ionic strength dependence and binding in the presence of anionic, cationic and non-ionic surfactants indicate, involvement of more that a single type of interaction in the binding process. The ITC results for the binding of these drugs to BSA in presence of each other indicate that the binding sites for the two drugs are different, and therefore binding of one is not influenced by the other. The DSC results provide quantitative information on the effect of these drugs on the stability of serum albumin. The combined calorimetric and spectroscopic approach has provided a detailed analysis including thermodynamics of the binding of DCF and CFT with BSA qualitatively and quantitatively.

  8. Enzyme kinetics determined by single-injection isothermal titration calorimetry.

    Science.gov (United States)

    Transtrum, Mark K; Hansen, Lee D; Quinn, Colette

    2015-04-01

    The purposes of this paper are (a) to examine the effect of calorimeter time constant (τ) on heat rate data from a single enzyme injection into substrate in an isothermal titration calorimeter (ITC), (b) to provide information that can be used to predict the optimum experimental conditions for determining the rate constant (k2), Michaelis constant (KM), and enthalpy change of the reaction (ΔRH), and (c) to describe methods for evaluating these parameters. We find that KM, k2 and ΔRH can be accurately estimated without correcting for the calorimeter time constant, τ, if (k2E/KM), where E is the total active enzyme concentration, is between 0.1/τ and 1/τ and the reaction goes to at least 99% completion. If experimental conditions are outside this domain and no correction is made for τ, errors in the inferred parameters quickly become unreasonable. A method for fitting single-injection data to the Michaelis-Menten or Briggs-Haldane model to simultaneously evaluate KM, k2, ΔRH, and τ is described and validated with experimental data. All four of these parameters can be accurately inferred provided the reaction time constant (k2E/KM) is larger than 1/τ and the data include enzyme saturated conditions. Copyright © 2014 Elsevier Inc. All rights reserved.

  9. The mechanism of interactions between tea polyphenols and porcine pancreatic alpha-amylase: Analysis by inhibition kinetics, fluorescence quenching, differential scanning calorimetry and isothermal titration calorimetry.

    Science.gov (United States)

    Sun, Lijun; Gidley, Michael J; Warren, Frederick J

    2017-10-01

    This study aims to use a combination of biochemical and biophysical methods to derive greater mechanistic understanding of the interactions between tea polyphenols and porcine pancreatic α-amylase (PPA). The interaction mechanism was studied through fluorescence quenching (FQ), differential scanning calorimetry (DSC) and isothermal titration calorimetry (ITC) and compared with inhibition kinetics. The results showed that a higher quenching effect of polyphenols corresponded to a stronger inhibitory activity against PPA. The red-shift of maximum emission wavelength of PPA bound with some polyphenols indicated a potential structural unfolding of PPA. This was also suggested by the decreased thermostability of PPA with these polyphenols in DSC thermograms. Through thermodynamic binding analysis of ITC and inhibition kinetics, the equilibrium of competitive inhibition was shown to result from the binding of particularly galloylated polyphenols with specific sites on PPA. There were positive linear correlations between the reciprocal of competitive inhibition constant (1/Kic ), quenching constant (KFQ ) and binding constant (Kitc ). The combination of inhibition kinetics, FQ, DSC and ITC can reasonably characterize the interactions between tea polyphenols and PPA. The galloyl moiety is an important group in catechins and theaflavins in terms of binding with and inhibiting the activity of PPA. © 2017 The Authors. Molecular Nutrition & Food Research Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Direct calorimetry: a brief historical review of its use in the study of human metabolism and thermoregulation.

    Science.gov (United States)

    Kenny, Glen P; Notley, Sean R; Gagnon, Daniel

    2017-07-08

    Direct calorimetry is the gold standard means of measuring human metabolic rate and its use has been fundamental for understanding metabolism in health and disease. While metabolic rate is now more commonly estimated indirectly from measures of the oxygen consumed during respiration, direct calorimetry provides the user with the unique capacity to quantify the heat produced from aerobic and anaerobic metabolism by measuring heat exchange between the body and the environment. This review provides a brief historical overview of the fundamental concepts which underlie direct calorimetry, of pioneer scientists which developed these concepts into functional pieces of equipment and the subsequent use of direct calorimetry to advance our understanding of energy balance, nutrition, and the pathogenesis of metabolic diseases. Attention is directed to seminal studies that successfully employed direct calorimetry to verify that the law of energy conservation also applies to human beings and to establish the validity of indirect calorimetry. Finally, we discuss the more recent use of direct calorimetry for the measurement of whole-body heat exchange and body heat storage in the study of human thermoregulation.

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

    Science.gov (United States)

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

    2003-01-01

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

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

    Science.gov (United States)

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

    2014-03-01

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

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

    Science.gov (United States)

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

    2016-10-01

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

  14. Effects of lipid membrane curvature on lipid packing state evaluated by isothermal titration calorimetry.

    Science.gov (United States)

    Yokoyama, Hirokazu; Ikeda, Keisuke; Wakabayashi, Masaki; Ishihama, Yasushi; Nakano, Minoru

    2013-01-22

    In this report, we present a novel approach for the elucidation of the physicochemical properties of lipid membranes by isothermal titration calorimetry (ITC) to quantify the heat absorbed during the solubilization of vesicles into TritonX-100 micelles. By using large and small unilamellar vesicles for comparison, this method provides calorimetric data on the gel-to-liquid-crystalline phase transition and its curvature effects and, in particular, the enthalpy change upon membrane deformation from a planar to a curved shape, which cannot be obtained by the conventional approach using differential scanning calorimetry. The results showed quantitatively that the increase in membrane curvature increases the enthalpy of 1,2-dimyristoyl-sn-glycero-3-phosphocholine membranes both below and above the phase-transition temperature, and that the effect is more significant for the former condition. The calorimetric data obtained are further discussed in relation to the elastic bending energy of the membranes and membrane-peptide interaction.

  15. Modulated Temperature Differential Scanning Calorimetry Theoretical and Practical Applications in Polymer Characterisation

    CERN Document Server

    Reading, Mike

    2006-01-01

    MTDSC provides a step-change increase in the power of calorimetry to characterize virtually all polymer systems including curing systems, blends and semicrystalline polymers. It enables hidden transitions to be revealed, miscibility to be accurately assessed, and phases and interfaces in complex blends to be quantified. It also enables crystallinity in complex systems to be measured and provides new insights into melting behaviour. All of this is achieved by a simple modification of conventional DSC. In 1992 a new calorimetric technique was introduced that superimposed a small modulation on top of the conventional linear temperature program typically used in differential scanning calorimetry. This was combined with a method of data analysis that enabled the sample’s response to the linear component of the temperature program to be separated from its response to the periodic component. In this way, for the first time, a signal equivalent to that of conventional DSC was obtained simultaneously with a measure ...

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

    Science.gov (United States)

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

    2017-02-20

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

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

    Science.gov (United States)

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

    2017-02-01

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

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

    Science.gov (United States)

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

    2017-01-01

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

  19. Application of calorimetry in evaluation of phase transformations in the selected hypoeutectic silumins

    Directory of Open Access Journals (Sweden)

    J. Szymszal

    2009-04-01

    Full Text Available The investigations of phase transformations described in this study were carried out on hypoeutectic alloys from the Al-Si during heating and cooling. The determination and analysis of characteristic temperature values from the solidification range was made by the DSC method in calorimetric investigations carried out on a high-temperature multi HTC Setaram scanning calorimeter. Applying the lever rule, the phase composition of the examined slumins was calculated and compared with the results of DSC calorimetry.

  20. Investigation of used Conveyor Belts by the Differential Scanning Calorimetry Analysis

    Directory of Open Access Journals (Sweden)

    Lucia Knapcikova,

    2016-02-01

    Full Text Available In this paper is presented the use of differential scanning calorimetry analysis of the used conveyor belts. This method has been specifically tested on the individual components contained in the used conveyor belts esp. rubber pellets, cord and fabric. The result of the analysis is the determination of Tg temperature and melting temperatures (Tm by the components.Weanalyzed used conveyor belts and after this analysis it was determined components and their application to the industry

  1. Nutrition Assessment With Indirect Calorimetry in Patients Evaluated for Left Ventricular Assist Device Implantation.

    Science.gov (United States)

    Yost, Gardner; Gregory, Mary; Bhat, Geetha

    2015-10-01

    Malnutrition is known to negatively impact the clinical course of advanced heart failure and is associated with increased mortality following left ventricular assist device (LVAD) implantation. Appropriate assessment of nutrition requirements in these patients is critical in their clinical care, yet there has been little discussion on how to best determine resting energy expenditure (REE) in the hospital setting. We investigated the use of indirect calorimetry in a group of patients with advanced heart failure. Results from preoperative indirect calorimetry testing in 98 patients undergoing evaluation for LVAD candidacy were collected. REE was compared with 10 predictive equations that estimated caloric need based on a range of patient-specific demographic and clinical variables. This study enrolled 22 female and 76 male patients with a mean age of 59.4 ± 12.5 years, body mass index of 29.6 ± 6.0 kg/m(2), and ejection fraction of 19.4 ± 6.6%. The average REE by indirect calorimetry in this group was 1610.0 ± 612.7 kcal/d. All predictive equations significantly overestimated REE. However, those equations intended for use in the critically ill demonstrated the greatest accuracy, with the Brandi equation achieving both the highest correlation (r = 0.605, P calorimetry may be reliably and safely used to determine caloric requirements in patients with advanced heart failure. The use of predictive equations based on demographic and clinical parameters appears to generate inaccurate estimations of REE in these patients. However, equations designed for use in critically ill patients better estimate nutrition requirements than those designed for healthy individuals. © 2015 American Society for Parenteral and Enteral Nutrition.

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

    Science.gov (United States)

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

    2015-03-01

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

  3. Characterization of photomultiplier tubes in a novel secondary ionization mode for Secondary Emission Ionization Calorimetry

    CERN Document Server

    Tiras, E; Ogul, H; Southwick, D; Bilki, B; Nachtman, J; Onel, Y

    2016-01-01

    Hamamatsu single anode R7761 and multi-anode R5900-00-M16 Photomultiplier Tubes have been characterized for use in Secondary Emission Ionization Calorimetry study, that is a novel techique to measure the electromagnetic shower particles in extreme radiation environment. There are different SE modes used in the tests, developed from conventional PMT mode. Here, the technical design of secondary emission modules and characterization measurements of both SE modes and the PMT mode are reported.

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

    Science.gov (United States)

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

    2016-06-01

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

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

    Science.gov (United States)

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

    2004-12-01

    Indirect calorimetry is commonly used in research and clinical settings to assess characteristics of energy expenditure. Respiration chambers in indirect calorimetry allow measurements over long periods of time (e.g., hours to days) and thus the collection of large sets of data. Current methods of data analysis usually involve the extraction of only a selected small proportion of data, most commonly the data that reflects resting metabolic rate. Here, we describe a simple quantitative approach for the analysis of large data sets that is capable of detecting small differences in energy metabolism. We refer to it as the percent relative cumulative frequency (PRCF) approach and have applied it to the study of uncoupling protein-1 (UCP1) deficient and control mice. The approach involves sorting data in ascending order, calculating their cumulative frequency, and expressing the frequencies in the form of percentile curves. Results demonstrate the sensitivity of the PRCF approach for analyses of oxygen consumption (.VO2) as well as respiratory exchange ratio data. Statistical comparisons of PRCF curves are based on the 50th percentile values and curve slopes (H values). The application of the PRCF approach revealed that energy expenditure in UCP1-deficient mice housed and studied at room temperature (24 degrees C) is on average 10% lower (p calorimetry is increasingly used, and the PRCF approach provides a novel and powerful means for data analysis.

  6. The use of calorimetry in the biophysical characterization of small molecule alkaloids binding to RNA structures.

    Science.gov (United States)

    Kumar, Gopinatha Suresh; Basu, Anirban

    2016-05-01

    RNA has now emerged as a potential target for therapeutic intervention. RNA targeted drug design requires detailed thermodynamic characterization that provides new insights into the interactions and this together with structural data, may be used in rational drug design. The use of calorimetry to characterize small molecule-RNA interactions has emerged as a reliable and sensitive tool after the recent advancements in biocalorimetry. This review summarizes the recent advancements in thermodynamic characterization of small molecules, particularly some natural alkaloids binding to various RNA structures. Thermodynamic characterization provides information that can supplement structural data leading to more effective drug development protocols. This review provides a concise report on the use of isothermal titration calorimetry (ITC) and differential scanning calorimetry (DSC) techniques in characterizing small molecules, mostly alkaloids-RNA interactions with particular reference to binding of tRNA, single stranded RNA, double stranded RNA, poly(A), triplex RNA. It is now apparent that a combination of structural and thermodynamic data is essential for rational design of specific RNA targeted drugs. Recent advancements in biocalorimetry instrumentation have led to detailed understanding of the thermodynamics of small molecules binding to various RNA structures paving the path for the development of many new natural and synthetic molecules as specific binders to various RNA structures. RNA targeted drug design, that remained unexplored, will immensely benefit from the calorimetric studies leading to the development of effective drugs for many diseases. Copyright © 2015 Elsevier B.V. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

    Akchurin, Nural .

    2015-05-04

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

  8. Recent development of material calorimetry%材料量热学的发展现状

    Institute of Scientific and Technical Information of China (English)

    孙玉霞; 李荣德

    2000-01-01

    材料量热学是测量材料变化过程中与热有关的各种物理量(如热焓、熵值等)变化规律的一门学科,分析了国内外材料量热学的发展状况,尤其是对材料量热学中的热分析技术进行了论述,对热分析方法中的差热分析方法(DTA)和差示扫描量热法(DSC)的应用情况做了分析和展望.%Material calorimetry is a subject that measures the changing laws of physical quantities such as enthalpy and entropy that are related to thermal. Recent development of material calorimetry at home and abroad has been reviewed and especially Thermal Analysis (fA) in calorimetric methods has been discussed in the paper. Differential Thermal Analysis (DTA) and Differential Scanning Calorimetry (DSC) in thermal analysis have been analyzed in derail. Moreover, several suggestions have been put forward in the end.

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

    Science.gov (United States)

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

    2014-12-01

    Indirect calorimetry is often done early in the morning in a fasting state, with the subject unshowered and abstained from caffeine or other stimulants. Subjects often fall asleep, resulting in measurement of a sleeping metabolic rate rather than a resting metabolic rate. The objective of this study was to determine whether listening to self-selected relaxing music or reading an electronic device or magazine affects resting energy expenditure (REE) during measurement in healthy adults. A randomized trial comparing three different conditions (ie, resting, reading, and listening to music) was performed. Sixty-five subjects (36 female and 29 male) were used in final data analysis. Inclusion criteria included healthy subjects between the ages of 18 and 50 years with a stable weight. Exclusion criteria included pregnant or lactating women or use of medications known to affect metabolism. Results showed that reading either a magazine or an electronic device significantly increased REE by 102.7 kcal/day when compared with resting (Pmusic increased REE by 27.6 kcal/day compared with rest (P=0.0072). Based on our results, we recommend subjects refrain from reading a magazine or electronic device during an indirect calorimetry test. Whether or not the smaller difference found while listening to music is practically significant would be a decision for the indirect calorimetry test administrator.

  10. STAR Calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Jacobs, W W, E-mail: jacobsw@indiana.ed [Indiana University Cyclotron Facility and Department of Physics, 2401 Milo B. Sampson Lane, Bloomington IN 47408 (United States)

    2009-04-01

    The main STAR calorimeters comprise a full Barrel EMC and single Endcap EMC plus a Forward Meson Spectrometer. Together they give a nearly complete coverage over the range -1 < pseudorapidity < 4 and provide EM readout and triggering that help drive STAR physics capabilities. Their description, status, performance and operations (and a few physics anecdotes) are briefly presented and discussed.

  11. Picosecond calorimetry

    DEFF Research Database (Denmark)

    Georgiou, Panayiotis; Vincent, Jonathan; Andersson, Magnus

    2006-01-01

    Liquid phase time-resolved x-ray diffraction with 100 ps resolution has recently emerged as a powerful technique for probing the structural dynamics of transient photochemical species in solution. It is intrinsic to the method, however, that a structural signal is observed not only from the photo...

  12. Picosecond calorimetry

    DEFF Research Database (Denmark)

    Georgiou, Panayiotis; Vincent, Jonathan; Andersson, Magnus

    2006-01-01

    to rapidly heat liquid C H2 Cl2 using UV pulses of 100 fs duration. A significant x-ray diffraction signal is visible prior to the onset of thermal expansion, which characterizes a highly compressed superheated liquid. Liquid C H2 Cl2 then expands as a shock wave propagates through the sample...

  13. Thermal Analysis of Whole Bacterial Cells Exposed to Potassium Permanganate Using Differential Scanning Calorimetry: a Biphasic Dose-Dependent Response to Stress

    Directory of Open Access Journals (Sweden)

    Marina K. Abuladze

    2009-01-01

    Full Text Available Differential scanning calorimetry (DSC was applied to estimate the impact of the toxic oxidant potassium permanganate (PM on the intracellular structural and functional alterations at whole cell level using soil bacteria Arthrobacter oxydans as a model culture. Differential scanning calorimetry (DSC was applied in order to estimate the impact of the toxic oxidant potassium permanganate (PM on the intracellular structural and functional alterations at the whole cell level using the soil bacteria Arthrobacter oxydans as a model culture. We compared the total melting heat and the temperature of DNA-protein complex (DNP melting at the PM application prior to the calorimetry measurement and after 24-h exposure at the concentration range 0.02–1.4 mM. The initial oxidative effect caused changes in the pattern of the whole cell melting spectra (mainly at the temperature range 56–78°C, the decrease of Tmax °C DNP melting, and did not influence significantly the total heat of bacterial melting at different concentrations of PM. The prolonged effect of permanganate up to 24 h was characterized by a biphasic dose-dependent response to stress estimated by the DSC technique and the colony-forming assay. The low doses of PM (0.02 and 0.2 mM stimulated cell proliferation, and increased the total whole cell melting heat and the temperature of DNP melting. The toxic effect of PM up to 0.04 mM reduced cell viability, changed the character of multipeaked thermograms, and lowered the total melting heat and the temperature of DNP melting in a concentration-dependent manner. This study presents the DSC method for evaluating and monitoring the effects of exposure to potential human and environmental toxicants.

  14. An Explicit Formulation Approach for the Analysis of Calcium Binding to EF-Hand Proteins Using Isothermal Titration Calorimetry

    Science.gov (United States)

    Keeler, Camille; Poon, Gregory; Kuo, Ivana Y.; Ehrlich, Barbara E.; Hodsdon, Michael E.

    2013-01-01

    We present an improved and extended version of a recently proposed mathematical approach for modeling isotherms of ligand-to-macromolecule binding from isothermal titration calorimetry. Our approach uses ordinary differential equations, solved implicitly and numerically as initial value problems, to provide a quantitative description of the fraction bound of each competing member of a complex mixture of macromolecules from the basis of general binding polynomials. This approach greatly simplifies the formulation of complex binding models. In addition to our generalized, model-free approach, we have introduced a mathematical treatment for the case where ligand is present before the onset of the titration, essential for data analysis when complete removal of the binding partner may disrupt the structural and functional characteristics of the macromolecule. Demonstration programs playable on a freely available software platform are provided. Our method is experimentally validated with classic calcium (Ca2+) ion-selective potentiometry and isotherms of Ca2+ binding to a mixture of chelators with and without residual ligand present in the reaction vessel. Finally, we simulate and compare experimental data fits for the binding isotherms of Ca2+ binding to its canonical binding site (EF-hand domain) of polycystin 2, a Ca2+-dependent channel with relevance to polycystic kidney disease. PMID:24359756

  15. Application of calorimetry and thermal analysis to determine the liquid range and the environmental toxicity of ionic liquids

    OpenAIRE

    Parajó Vieito, Juan José

    2016-01-01

    This PhD Thesis is focused on the applicability of thermal analysis and calorimetry techniques to determine phase transitions (through Differential Scanning Calorimetry (DSC)), thermal stability (measured by Thermogravimetric Analysis (TGA)) and ecotoxicity (trhough Thermal Activity Monitor (TAM) and seed germination response tests) of ionic liquids (ILs) to be used as lubricants and/or absorbents in heat pumps. The studied compounds are based on different anions (imide, triflate, sulphonate,...

  16. PHOENIX: a scoring function for affinity prediction derived using high-resolution crystal structures and calorimetry measurements.

    Science.gov (United States)

    Tang, Yat T; Marshall, Garland R

    2011-02-28

    Binding affinity prediction is one of the most critical components to computer-aided structure-based drug design. Despite advances in first-principle methods for predicting binding affinity, empirical scoring functions that are fast and only relatively accurate are still widely used in structure-based drug design. With the increasing availability of X-ray crystallographic structures in the Protein Data Bank and continuing application of biophysical methods such as isothermal titration calorimetry to measure thermodynamic parameters contributing to binding free energy, sufficient experimental data exists that scoring functions can now be derived by separating enthalpic (ΔH) and entropic (TΔS) contributions to binding free energy (ΔG). PHOENIX, a scoring function to predict binding affinities of protein-ligand complexes, utilizes the increasing availability of experimental data to improve binding affinity predictions by the following: model training and testing using high-resolution crystallographic data to minimize structural noise, independent models of enthalpic and entropic contributions fitted to thermodynamic parameters assumed to be thermodynamically biased to calculate binding free energy, use of shape and volume descriptors to better capture entropic contributions. A set of 42 descriptors and 112 protein-ligand complexes were used to derive functions using partial least-squares for change of enthalpy (ΔH) and change of entropy (TΔS) to calculate change of binding free energy (ΔG), resulting in a predictive r2 (r(pred)2) of 0.55 and a standard error (SE) of 1.34 kcal/mol. External validation using the 2009 version of the PDBbind "refined set" (n = 1612) resulted in a Pearson correlation coefficient (R(p)) of 0.575 and a mean error (ME) of 1.41 pK(d). Enthalpy and entropy predictions were of limited accuracy individually. However, their difference resulted in a relatively accurate binding free energy. While the development of an accurate and applicable

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

    Science.gov (United States)

    Bruylants, G; Wouters, J; Michaux, C

    2005-01-01

    All biological phenomena depend on molecular recognition, which is either intermolecular like in ligand binding to a macromolecule or intramolecular like in protein folding. As a result, understanding the relationship between the structure of proteins and the energetics of their stability and binding with others (bio)molecules is a very interesting point in biochemistry and biotechnology. It is essential to the engineering of stable proteins and to the structure-based design of pharmaceutical ligands. The parameter generally used to characterize the stability of a system (the folded and unfolded state of the protein for example) is the equilibrium constant (K) or the free energy (deltaG(o)), which is the sum of enthalpic (deltaH(o)) and entropic (deltaS(o)) terms. These parameters are temperature dependent through the heat capacity change (deltaCp). The thermodynamic parameters deltaH(o) and deltaCp can be derived from spectroscopic experiments, using the van't Hoff method, or measured directly using calorimetry. Along with isothermal titration calorimetry (ITC), differential scanning calorimetry (DSC) is a powerful method, less described than ITC, for measuring directly the thermodynamic parameters which characterize biomolecules. In this article, we summarize the principal thermodynamics parameters, describe the DSC approach and review some systems to which it has been applied. DSC is much used for the study of the stability and the folding of biomolecules, but it can also be applied in order to understand biomolecular interactions and can thus be an interesting technique in the process of drug design.

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

    Energy Technology Data Exchange (ETDEWEB)

    Adloff, C.; Chefdeville, M., E-mail: chefdevi@lapp.in2p3.fr; Dalmaz, A.; Drancourt, C.; Gaglione, R.; Geffroy, N.; Jacquemier, J.; Karyotakis, Y.; Koletsou, I.; Peltier, F.; Samarati, J.; Vouters, G.

    2014-11-01

    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 m{sup 2} 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.

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

    CERN Document Server

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

    2014-01-01

    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 to 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$\\times$1 m$^{2}$ 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.

  20. Software solution for control and data acquisition in the pulse calorimetry method

    Directory of Open Access Journals (Sweden)

    Babić Marijana

    2013-01-01

    Full Text Available This work presents a software solution for adjusting, controlling, displaying, and acquiring parameters and data in the pulse calorimetry experimental technique for specific heat capacity, electrical resistivity, total hemispherical emissivity, and normal spectral emissivity measurements. The software has been developed under the LabVIEW platform, V.7.11, and an example of its application with measurement results is presented in a separate section. The total expanded uncertainty of obtained results for the specific heat capacity and electrical resistivity of palladium was 5% and 1 - 2%, respectively.

  1. Application of calorimetry in evaluation of phase transformations in the selected hypoeutectic silumins

    Directory of Open Access Journals (Sweden)

    J. Piątkowski

    2008-12-01

    Full Text Available The investigations of phase transformations described in this study were carried out on hypoeutectic alloys from the Al-Si system (AlSi3, AlSi6 and AlSi9 during heating and cooling. The determination and analysis of characteristic temperature values from the solidification range was made by the DSC method in calorimetric investigations carried out on a high-temperature multi HTC scanning calorimeter. Applying the lever rule, the phase composition of the examined silumins was calculated and compared with the results of DSC calorimetry, obtaining a good correlation of the results.

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

    Science.gov (United States)

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

    2010-02-01

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

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

    Science.gov (United States)

    Rao, Linfeng

    2007-06-01

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

  4. Impact of sample saturation on the detected porosity of hardened concrete using low temperature calorimetry

    DEFF Research Database (Denmark)

    Wu, Min; Johannesson, Björn

    2014-01-01

    The present work studied the impact of sample saturation on the analysis of pore volume and pore size distribution by low temperature (micro-)calorimetry. The theoretical background was examined, which emphasizes that the freezing/melting temperature of water/ice confined in non-fully saturated...... pores is further depressed compared with that when the pores are fully saturated. The study of the experimental data on hardened concrete samples showed that for a same concrete mix, the total pore volume detected from the capillary saturated samples was always lower than that of the vacuum saturated...

  5. Determination of magnetic characteristics of nanoparticles by low-temperature calorimetry methods

    Energy Technology Data Exchange (ETDEWEB)

    Ugulava, A.; Toklikishvili, Z. [Department of Physics, I.Javakhishvili Tbilisi State University,I.Chavchavadze av. 3, 0179 Tbilisi, Georgia (United States); Chkhaidze, S., E-mail: simon.chkhaidze@tsu.ge [Department of Physics, I.Javakhishvili Tbilisi State University,I.Chavchavadze av. 3, 0179 Tbilisi, Georgia (United States); Kekutia, Sh. [V. Chavchanidze Institute of Cybernetics, at the Technical State University, S. Euli str. 5, 0186 Tbilisi, Georgia (United States)

    2017-05-15

    At low temperatures, the heat capacity of a superparamagnetic “ideal gas” determined by magnetic degrees of freedom can greatly exceed the lattice heat capacity. It is shown that in the presence of an external magnetic field, the temperature dependence of the magnetic part of the heat capacity has two maxima. The relations between the temperature at which these maxima are achieved, the magnetic moment of the nanoparticles and the magnetic anisotropy constant have been obtained. Measuring the heat capacity maxima temperatures by low-temperature calorimetry methods and using the obtained relations, we can obtain the numerical values both of the magnetic moment of nanoparticles and the magnetic anisotropy constants.

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

    Science.gov (United States)

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

    2015-06-04

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

  7. Using Isothermal Titration Calorimetry to Determine Thermodynamic Parameters of Protein–Glycosaminoglycan Interactions

    Science.gov (United States)

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

    2015-01-01

    It has now become increasingly clear that a complete atomic description of how biomacromolecules recognize each other requires knowledge not only of the structures of the complexes but also of how kinetics and thermodynamics drive the binding process. In particular, such knowledge is lacking for protein–glycosaminoglycan (GAG) complexes. Isothermal titration calorimetry (ITC) is the only technique that can provide various thermodynamic parameters—enthalpy, entropy, free energy (binding constant), and stoichiometry—from a single experiment. Here we describe different factors that must be taken into consideration in carrying out ITC titrations to obtain meaningful thermodynamic data of protein–GAG interactions. PMID:25325962

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

    Directory of Open Access Journals (Sweden)

    Michael H Chiu

    2011-01-01

    Full Text Available 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.

  9. Preamplifiers for room temperature and cryogenic calorimetry applications based on DMILL technology

    Energy Technology Data Exchange (ETDEWEB)

    Ardelean, J. [Laboratoire de l`Accelerateur Lineaire, Orsay (France); Hrisoho, A. [Laboratoire de l`Accelerateur Lineaire, Orsay (France); Truong, K. [Laboratoire de l`Accelerateur Lineaire, Orsay (France); Manfredi, P.F. [Dipartimento di Elettronica, Via Abbiategrasso 209, 27100 Pavia (Italy)]|[INFN, Sezione di Milano, Via Celoria 16, 20133 Milano (Italy); Speziali, V. [Dipartimento di Elettronica, Via Abbiategrasso 209, 27100 Pavia (Italy)]|[INFN, Sezione di Milano, Via Celoria 16, 20133 Milano (Italy); Svelto, F. [Dipartimento di Elettronica, Via Abbiategrasso 209, 27100 Pavia (Italy)]|[INFN, Sezione di Milano, Via Celoria 16, 20133 Milano (Italy); Citterio, M. [Brookhaven National Laboratory, Upton, NY 11973 (United States)

    1996-07-01

    This paper discusses the results obtained with charge sensitive preamplifiers employing a large input device and suitable for room temperature as well as cryogenic calorimetry applications. The preamplifiers have been realised in DMILL technology, a process where all devices are on an insulating layer. Two preamplifier configurations are illustrated here. One of them is entirely based on P-channel JFETs, the other one employs PJFETs and NMOS. In both cases the input device is a PJFET with 1.2 {mu}m gate length, a device which was proven to feature outstanding noise performances. (orig.).

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

    Science.gov (United States)

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

    2008-10-01

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

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

    Science.gov (United States)

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

    2015-01-01

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

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

    Science.gov (United States)

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

    2016-09-01

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

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

    Science.gov (United States)

    Chiu, Michael H.; Prenner, Elmar J.

    2011-01-01

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

  14. Glassy behavior of denatured DNA films studied by differential scanning calorimetry.

    Science.gov (United States)

    Valle-Orero, Jessica; Garden, Jean-Luc; Richard, Jacques; Wildes, Andrew; Peyrard, Michel

    2012-04-12

    We use differential scanning calorimetry (DSC) to study the properties of DNA films, made of oriented fibers, heated above the thermal denaturation temperature of the double helical form. The films show glassy properties that we investigate in two series of experiments, a slow cooling at different rates followed by a DSC scan upon heating and aging at a temperature below the glass transition. Introducing the fictive temperature to characterize the glass allows us to derive quantitative information on the relaxations of the DNA films, in particular to evaluate their enthalpy barrier. A comparison with similar aging studies on PVAc highlights some specificities of the DNA samples.

  15. Optimization of the scintillation parameters of the lead tungstate crystals for their application in high precision electromagnetic calorimetry; Optimisation des parametres de scintillation des cristaux de tungstate de plomb pour leur application dans la calorimetrie electromagnetique de haute precision

    Energy Technology Data Exchange (ETDEWEB)

    Drobychev, G

    2000-04-12

    In the frame of this dissertation work scintillation properties of the lead tungstate crystals (PWO) and possibilities of their use were studied foreseeing their application for electromagnetic calorimetry in extreme radiation environment conditions of new colliders. The results of this work can be summarized in the following way. 1. A model of the scintillations origin in the lead tungstate crystals which includes processes influencing on the crystals radiation hardness and presence of slow components in scintillations was developed. 2. An analysis of the influences of the PWO scintillation properties changes on the parameters of the electromagnetic calorimeter was done. 3. Methods of the light collection from the large scintillation elements of complex shape made of the birefringent scintillation crystal with high refraction index and low light yield in case of signal registration by a photodetector with sensitive surface small in compare with the output face of scintillator were Studied. 4. Physical principles of the methodology of the scintillation crystals certification during their mass production foreseeing their installation into a calorimeter electromagnetic were developed. Correlations between the results of measurements of the PWO crystals parameters by different methods were found. (author)

  16. Methodology of hot nucleus calorimetry and thermometry produced by nuclear reactions around Fermi energies; Methodologie de la calorimetrie et de la thermometrie des noyaux chauds formes lors de collisions nucleaires aux energies de Fermi

    Energy Technology Data Exchange (ETDEWEB)

    Vient, E

    2006-12-15

    This work deals with the calorimetry and thermometry of hot nuclei produced in collisions Xe + Sn between 25 and 100 MeV/u. The apparatus for hot nucleus physical characterization is the 4{pi} detector array Indra. This study was made by using the event generators Gemini, Simon and Hipse and a data-processing filter simulating the complete operation of the multi-detector. The first chapter presents the different ways of producing hot nuclei. In the second and third chapters, the author presents a critical methodological study of calorimetry and thermometry applied to hot nuclei, different methods are reviewed, their accuracy and application range are assessed. All the calorimetry methods rely on the assumption that we are able to discriminate decay products of the hot nucleus from evaporated particles. In the fourth chapter, the author gives some ways of improving calorimetry characterization of the hot nucleus. An alternative method of calorimetry is proposed in the fifth chapter, this method is based on the experimental determination of an evaporation probability that is deduced from the physical characteristics of the particles present in a restricted domain of the space of velocities.

  17. Effect of heating and cooling rate on the kinetics of allotropic phase changes in uranium: A differential scanning calorimetry study

    Energy Technology Data Exchange (ETDEWEB)

    Rai, Arun Kumar [Physical Metallurgy Division, Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam 603 102, Tamilnadu (India); Raju, S. [Physical Metallurgy Division, Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam 603 102, Tamilnadu (India)], E-mail: sraju@igcar.gov.in; Jeyaganesh, B.; Mohandas, E. [Physical Metallurgy Division, Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam 603 102, Tamilnadu (India); Sudha, R.; Ganesan, V. [Materials Chemistry Division, Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam 603 102, Tamilnadu (India)

    2009-01-01

    The kinetic aspects of allotropic phase changes in uranium are studied as a function of heating/cooling rate in the range 10{sup 0}-10{sup 2} K min{sup -1} by isochronal differential scanning calorimetry. The transformation arrest temperatures revealed a remarkable degree of sensitivity to variations of heating and cooling rate, and this is especially more so for the transformation finish (T{sub f}) temperatures. The results obtained for the {alpha} {yields} {beta} and {beta} {yields} {gamma} transformations during heating confirm to the standard Kolmogorov-Johnson-Mehl-Avrami (KJMA) model for a nucleation and growth mediated process. The apparent activation energy Q{sub eff} for the overall transformation showed a mild increase with increasing heating rate. In fact, the heating rate normalised Arrhenius rate constant, k/{beta} reveals a smooth power law decay with increasing heating rate ({beta}). For the {alpha} {yields} {beta} phase change, the observed DSC peak profile for slower heating rates contained a distinct shoulder like feature, which however is absent in the corresponding profiles found for higher heating rates. The kinetics of {gamma} {yields} {beta} phase change on the other hand, is best described by the two-parameter Koistinen-Marburger empirical relation for the martensitic transformation.

  18. Isothermal titration calorimetry for drug design: Precision of the enthalpy and binding constant measurements and comparison of the instruments.

    Science.gov (United States)

    Linkuvienė, Vaida; Krainer, Georg; Chen, Wen-Yih; Matulis, Daumantas

    2016-12-15

    Isothermal titration calorimetry (ITC) is one of the most robust label- and immobilization-free techniques used to measure protein - small molecule interactions in drug design for the simultaneous determination of the binding affinity (ΔG) and the enthalpy (ΔH), both of which are important parameters for structure-thermodynamics correlations. It is important to evaluate the precision of the method and of various ITC instrument models by performing a single well-characterized reaction. The binding between carbonic anhydrase II and acetazolamide was measured by four ITC instruments - PEAQ-ITC, iTC200, VP-ITC, and MCS-ITC and the standard deviation of ΔG and ΔH was determined. Furthermore, the limit of an approach to reduce the protein concentration was studied for a high-affinity reaction (Kd = 0.3 nM), too tight to be measured by direct (non-displacement) ITC. Chemical validation of the enthalpy measurements is discussed. Copyright © 2016 Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

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

    2014-12-31

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

  20. The thermal stability and domain interactions of the mannitol permease of Escherichia coli. A differential scanning calorimetry study.

    Science.gov (United States)

    Meijberg, W; Schuurman-Wolters, G K; Boer, H; Scheek, R M; Robillard, G T

    1998-08-14

    The thermal stability and domain interactions in the mannitol transporter from Escherichia coli, enzyme IImtl, have been studied by differential scanning calorimetry. To this end, the wild type enzyme, IICBAmtl, as well as IICBmtl and IICmtl, were reconstituted into a dimyristoylphosphatidylcholine lipid bilayer. The changes in the gel to liquid crystalline transition of the lipid indicated that the protein was inserted into the membrane, disturbing a total of approximately 40 lipid molecules/protein molecule. The thermal unfolding profile of EIImtl exhibited three separate transitions, two of which were overlapping, that could be assigned to structural domains in the protein. Treatment with trypsin, resulting in the degradation of the water-soluble part of the enzyme while leaving the binding and translocation capability of the enzyme intact, resulted in a decrease of the Tm and enthalpy of unfolding of the membrane-embedded C domain. This effect was much more apparent in the presence of the substrate but only partly so in the presence of the substrate analog perseitol. These results are consistent with a recently proposed model (Meijberg, W., Schuurman-Wolters, G. K., and Robillard, G. T. (1998) J. Biol. Chem. 273, 7949-7946), in which the B domain takes part in the conformational changes during the substrate binding process.

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

    Science.gov (United States)

    Bye, Jordan W; Falconer, Robert J

    2015-06-07

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

  2. Assessment of lifetime resolution limits in time-resolved photoacoustic calorimetry vs. transducer frequencies: setting the stage for picosecond resolution.

    Science.gov (United States)

    Schaberle, Fábio A; Rego Filho, Francisco de Assis M G; Reis, Luís A; Arnaut, Luis G

    2016-02-01

    Time-resolved photoacoustic calorimetry (PAC) gives access to lifetimes and energy fractions of reaction intermediates by deconvolution of the photoacoustic wave of a sample (E-wave) with that of the instrumental response (T-wave). The ability to discriminate between short lifetimes increases with transducer frequencies employed to detect the PAC waves. We investigate the lifetime resolution limits of PAC as a function of the transducer frequencies using the instrumental response obtained with the photoacoustic reference 2-hydroxybenzophenone in toluene or acetonitrile. The instrumental response was obtained for a set of transducers with central frequencies ranging from 0.5 MHz up to 225 MHz. The simulated dependence of the lifetime resolution with the transducer frequencies was anchored on experimental data obtained for the singlet state of naphthalene with a 2.25 MHz transducer. The shortest lifetime resolved with the 2.25 MHz transducer was 19 ns and our modelling of the transducer responses indicates that sub-nanosecond lifetimes of photoacoustic transients can be resolved with transducers of central frequencies above 100 MHz.

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

    Science.gov (United States)

    Tabbakhian, M.; Rogers, J.A.

    2012-01-01

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

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

    Science.gov (United States)

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

    2013-02-13

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

  5. Practical approach for measuring heat capacity of pharmaceutical crystals/glasses by modulated-temperature differential scanning calorimetry.

    Science.gov (United States)

    Harada, Takuji; Kawakami, Kohsaku; Yoshihashi, Yasuo; Yonemochi, Etsuo; Terada, Katsuhide; Moriyama, Hiroshi

    2013-01-01

    A practical protocol to obtain accurate heat capacity values of pharmaceutical compounds using modulated-temperature differential scanning calorimetry was established. Three pharmaceutical compounds, acetaminophen, indomethacin, and tri-O-methyl-β-cyclodextrin were used as model compounds. Powder samples did not produce reproducible results, presumably due to inclusion of gas in gap of powders that influenced the measured heat capacity and thermal homogeneity in the sample. Thus, the amorphous characteristics were evaluated using quench-cooled samples. Crystalline samples were obtained by partially melting the sample to allow recrystallization using the residual crystal as a template. Optimum sample mass was about 10 mg. Use of too small sample size resulted in poor reproducibility due to localization of the sample in the pan, while too large size resulted in low heat capacity values probably because of heterogeneity of the sample temperature. The optimum modulation period was in the range of 60 s and 90 s, to which the ramp rates of 2°C/min and 1°C/min, respectively, were applied. The ramp amplitude was less significant in the evaluation. This information should help in comprehending basic characteristics of pharmaceutical compounds.

  6. A preliminary study of the influence of ions in the pore solution of hardened cement pastes on the porosity determination by low temperature calorimetry

    DEFF Research Database (Denmark)

    Wu, Min; Johannesson, Björn; Geiker, Mette

    2014-01-01

    Thermodynamic modeling was used to predict the ionic concentrations in the pore solution of cement pastes at different temperatures during a freezing and melting measurement in low temperature calorimetry (LTC) studies. By using the predicted ionic concentrations, the temperature depressions caused...... by the ions presented in the pore solution were determined. The influence of the freezing/melting point depression caused by the ions on the determined pore size distribution by LTC was demonstrated. Thermodynamic modeling using the program PHREEQC was performed on the cylinder and powder samples of cement...... pastes prepared by two types of cements, i.e., CEM 132.5 R and CEM III/B 42.5 N. Using the modeled ionic concentrations, the calculated differential pore size distributions for the studied samples with and without considering the temperature depression caused by the ions in the pore solution were...

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

    Science.gov (United States)

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

    2011-03-01

    Enzymatic hydrolysis of high-solid biomass (>10% w/w dry mass) has become increasingly important as a key step in the production of second-generation bioethanol. To this end, development of quantitative real-time assays is desirable both for empirical optimization and for detailed kinetic analysis. In the current work, we have investigated the application of isothermal calorimetry to study the kinetics of enzymatic hydrolysis of two substrates (pretreated corn stover and Avicel) at high-solid contents (up to 29% w/w). It was found that the calorimetric heat flow provided a true measure of the hydrolysis rate with a detection limit of about 500 pmol glucose s(-1). Hence, calorimetry is shown to be a highly sensitive real-time method, applicable for high solids, and independent on the complexity of the substrate. Dose-response experiments with a typical cellulase cocktail enabled a multidimensional analysis of the interrelationships of enzyme load and the rate, time, and extent of the reaction. The results suggest that the hydrolysis rate of pretreated corn stover is limited initially by available attack points on the substrate surface (10% conversion). 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.

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

    Science.gov (United States)

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

    2013-01-01

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

  9. Volume and expansivity changes of micelle formation measured by pressure perturbation calorimetry.

    Science.gov (United States)

    Fan, Helen Y; Nazari, Mozhgan; Chowdhury, Saria; Heerklotz, Heiko

    2011-03-01

    We present the application of pressure perturbation calorimetry (PPC) as a new method for the volumetric characterization of the micelle formation of surfactants. The evaluation is realized by a global fit of PPC curves at different surfactant concentration ranging, if possible, from below to far above the CMC. It is based on the knowledge of the temperature dependence of the CMC, which can for example be characterized by isothermal titration calorimetry. We demonstrate the new approach for decyl-β-maltopyranoside (DM). It shows a strong volume increase upon micelle formation of 16 ± 2.5 mL/mol (+4%) at 25 °C, and changes with temperature by -0.1 mL/(mol K). The apparent molar expansivity (E(S)) decreases upon micelle formation from 0.44 to 0.31 mL/(mol K) at 25 °C. Surprisingly, the temperature dependence of the expansivity of DM in solution (as compared with that of maltose) does not agree with the principal behavior described for polar (E(S)(T) decreasing) and hydrophobic (E(S)(T) increasing) solutes or moieties before. The results are discussed in terms of changes in hydration of the molecules and internal packing of the micelles and compared with the volumetric effects of transitions of proteins, DNA, lipids, and polymers.

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

    Energy Technology Data Exchange (ETDEWEB)

    Lyons, J.E.

    1989-12-31

    The goals of the Calorimetry Sample Exchange Program are to: discuss measurement differences; review and improve analytical measurements and methods; discuss new measurement capabilities; provide data to DOE on measurement capabilities to evaluate shipper-receiver differences; provide characterized or standard materials as necessary for exchange participants; and provide a measurement control program for plutonium analysis. A sample of PuO{sub 2} powder is available at each participating site for NDA measurement, including either or both calorimetry and high-resolution gamma-ray spectroscopy, the elements which are typically combined to provide a calorimetric assay of plutonium. The facilities measure the sample as frequently and to the level of precision which they desire, and then submit the data to the Exchange for analysis. Statistical tests are used to evaluate the data and to determine if there are significant differences from accepted values for the exchange sample or from data previously reported by that facility. This information is presented, in the form of a quarterly report, intended for use by Exchange participants in measurement control programs, or to indicate when bias corrections may be appropriate. No attempt, however, has been made to standardize methods or frequency of data collection, calibration, or operating procedures. Direct comparisons between laboratories may, therefore, be misleading since data have not bee collected to the same precision or for the same time periods. The six participating laboratories are Lawrence Livermore, Los Alamos, MRC-Mound, Westinghouse Hanford, Rocky Flats, and Savannah River.

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

    Science.gov (United States)

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

    2016-01-01

    Many labs have conventional calorimeters where denaturation and binding experiments are setup and run one at a time. While these systems are highly informative to biopolymer folding and ligand interaction, they require considerable manual intervention for cleaning and setup. As such, the throughput for such setups is limited typically to a few runs a day. With a large number of experimental parameters to explore including different buffers, macromolecule concentrations, temperatures, ligands, mutants, controls, replicates, and instrument tests, the need for high-throughput automated calorimeters is on the rise. Lower sample volume requirements and reduced user intervention time compared to the manual instruments have improved turnover of calorimetry experiments in a high-throughput format where 25 or more runs can be conducted per day. The cost and efforts to maintain high-throughput equipment typically demands that these instruments be housed in a multiuser core facility. We describe here the steps taken to successfully start and run an automated biological calorimetry facility at Pennsylvania State University. Scientists from various departments at Penn State including Chemistry, Biochemistry and Molecular Biology, Bioengineering, Biology, Food Science, and Chemical Engineering are benefiting from this core facility. Samples studied include proteins, nucleic acids, sugars, lipids, synthetic polymers, small molecules, natural products, and virus capsids. This facility has led to higher throughput of data, which has been leveraged into grant support, attracting new faculty hire and has led to some exciting publications. © 2016 Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

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

    2014-01-01

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

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

    Science.gov (United States)

    Pandharipande, Pranav P; Makhatadze, George I

    2015-04-01

    The main goal of this work was to provide direct experimental evidence that the expansivity of peptides, polypeptides and proteins as measured by pressure perturbation calorimetry (PPC), can serve as a proxy to characterize relative compactness of proteins, especially the denatured state ensemble. This is very important as currently only small angle X-ray scattering (SAXS), intrinsic viscosity and, to a lesser degree, fluorescence resonance transfer (FRET) experiments are capable of reporting on the compactness of denatured state ensembles. We combined the expansivity measurements with other biophysical methods (far-UV circular dichroism spectroscopy, differential scanning calorimetry, and small angle X-ray scattering). Three case studies of the effects of conformational changes on the expansivity of polypeptides in solution are presented. We have shown that expansivity appears to be insensitive to the helix-coil transition, and appears to reflect the changes in hydration of the side-chains. We also observed that the expansivity is sensitive to the global conformation of the polypeptide chain and thus can be potentially used to probe hydration of different collapsed states of denatured or even intrinsically disordered proteins. Copyright © 2015 Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

    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

    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). © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  15. Resistivity and AC calorimetry measurements on CeNiGe{sub 2} under pressure

    Energy Technology Data Exchange (ETDEWEB)

    Holmes, A.T. [KYOKUGEN, Osaka University, Toyonaka, Osaka 560-8531 (Japan)]. E-mail: alex@djebel.mp.es.osaka-u.ac.jp; Muramatsu, T. [KYOKUGEN, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Miyake, A. [KYOKUGEN, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Kaczorowski, D. [KYOKUGEN, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wroclaw (Poland); Bukowski, Z. [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wroclaw (Poland); Kagayama, T. [KYOKUGEN, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Shimizu, K. [KYOKUGEN, Osaka University, Toyonaka, Osaka 560-8531 (Japan)

    2007-03-15

    We present resistivity and AC calorimetry measurements of single crystalline CeNiGe{sub 2} under high pressure and low temperature in a diamond anvil cell. CeNiGe{sub 2} is a highly anisotropic, antiferromagnetic Kondo system at ambient pressure, located close to the boundary with non-magnetic systems. It has two ordering temperatures, T{sub N1}=3.9K and T{sub N2}=3.2K, which are suppressed under pressure. Between 0.7 and 1.4GPa only a single transition was identified, with T{sub N} reaching 1.9K by 1.4 GPa. At 1.9GPa two transitions could again be seen by AC calorimetry at 2.0 and 1.3K, accompanied by a qualitative change in the behaviour of the resistivity. The Sommerfeld coefficient showed a maximum of 755mJmol{sup -1}K{sup -2} at 1.4GPa, up from 448mJmol{sup -1}K{sup -2} at close to ambient pressure. The residual resistivity was found to decrease sharply above 1.4GPa after an initial increase with pressure.

  16. Monitoring of butter and animal fat oxidation stability by differential scanning calorimetry (DSC

    Directory of Open Access Journals (Sweden)

    Jasminka Sadadinović

    2005-07-01

    Full Text Available Oxidation of fat is one of the basic reactions which causes the depletion of butter and animal fat quality as well as other products containing them. Since the most of reaction products of fat oxidation are harmful for consumers' health, inadequate and scarce monitoring of edible fats and fat containing products quality, presents increased health risk as well as financial loss for the producers. In fat oxidation stability estimation, standard chemical methods were used (iodine number, acid number, peroxide number, anisidine number etc., which require time and chemical usage. Differential scanning calorimetry (DSC analysis presents the simple and efficient way for butter and animal fats oxidation stability estimation. Laboratory investigations were performed to monitor oxidation stability of butter and animal fat in fresh state, as well as in spent phase, used in frying process. The results obtained were compared to the results of standard chemical analysis, and they confirmed the reproducibility and applicability of differential scanning calorimetry in oxidation stability of butter and animal fats monitoring.

  17. Resting energy expenditure and body composition in children with cancer: indirect calorimetry and bioimpedance analysis

    Directory of Open Access Journals (Sweden)

    M. V. Konovalova

    2014-07-01

    Full Text Available Resting energy expenditure (REE by indirect calorimetry and body composition by bioimpedance analysis are studied in three groups of children aged 5–18 years. Group 1 (n = 181 – patients in remission of cancer, group 2 (n = 55 – children with oncology diseases receiving chemotherapy or who are in the early period after hematopoietic stem cell transplantation, group 3 (n = 63 – children with non-malignant diseases of the gastrointestinal tract. To eliminate the influence of age and gender on the intergroup comparisons, body composition parameters were expressed as standardized values (z-scores relative to a reference group of healthy Russian children (n = 138,191. Group 1 was characterized by excess fat content with intact lean body mass, and groups 2 and 3 by protein depletion, more pronounced in Group 2 with a higher percentage of body fat. All used conventional formulas (WHO, Harris–Benedict and others in groups 1 and 3 underestimated REE as compared with indirect calorimetry. A new formula for REE, giving an unbiased estimate in the group 1 was proposed: REE (kcal/day = 28.7 × BCM (kg +10.5 × Height (cm – 38.6 × Age (years – 134, where BCM – body cell mass according to bioimpedance analysis (R2 = 0.67, the standard deviation of 196 kcal/day.

  18. Calorimetry exchange program quarterly data report, 2nd quarter CY93

    Energy Technology Data Exchange (ETDEWEB)

    Barnett, T.M.

    1993-12-31

    The goals of the Calorimetry Sample Exchange Program are to: discuss measurement differences; review and improve analytical measurements and methods; discuss new measurement capabilities; provide data to DOE on measurement capabilities to evaluate shipper-receiver differences; provide characterized or standard materials as necessary for exchange participants; and provide a measurement control program for plutonium analysis. A sample of PuO{sub 2} powder is available at each participating site for NDA measurement, including either or both calorimetry and high-resolution gamma-ray spectroscopy, the elements which are typically combined to provide a calorimetric assay of plutonium. The facilities measure the sample as frequently and to the level of precision which they desire, and then submit the data to the exchange for analysis. The data report includes summary tables for each measurement and charts showing the performance of each laboratory. Comparisons are made to the accepted values for the exchange sample and to data previously reported by that laboratory. This information is presented, in the form of quarterly and annual reports, intended for use by Exchange participants in measurement control programs, or to indicate when bias corrections may be appropriate. No attempt, however, has been made to standardize methods or frequency of data collection, calibration, or operating procedures. Direct comparisons between laboratories may, therefore, be misleading since data have not been collected to the same precision or for the same time periods.

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

    Science.gov (United States)

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

    1990-01-01

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

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

    Science.gov (United States)

    Skotnicki, Marcin; Gaweł, Agnieszka; Cebe, Peggy; Pyda, Marek

    2013-10-01

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

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

    Science.gov (United States)

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

    2007-02-01

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

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

    Science.gov (United States)

    Novotny, Rainer W.

    2015-02-01

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

  3. The Curing Process of Epoxy/Amino-Functionalized MWCNTs: Calorimetry, Molecular Modelling, and Electron Microscopy

    Directory of Open Access Journals (Sweden)

    S. G. Prolongo

    2010-01-01

    Full Text Available Curing kinetic of an epoxy resin reinforced with amino-functionalized MWCNTs has been studied by DSC and the obtained results were explained through morphological studies carried out by SEM, TEM, FEG-SEM, and molecular simulation tools. The presence of MWCNTs in the curing reaction induces a retardation effect of curing reaction and a decrease of the reaction heat. Both are associated with the adsorption of curing agent molecules inside carbon nanotubes, which was proved through the application of electron microscopic techniques and molecular simulation tools. It has been also demonstrated that there is a chemical reaction between amine groups anchored to the nanotubes and oxirane rings of epoxy monomer, which improves the nanoreinforcement/matrix interfacial adhesion, appearing a chemical interphase. The glass transition temperature (Tg of epoxy matrix increases by the addition of MWCNTs due to the restriction of its mobility.

  4. Optics of the NIFS negative ion source test stand by infrared calorimetry and numerical modelling.

    Science.gov (United States)

    Veltri, P; Antoni, V; Agostinetti, P; Brombin, M; Ikeda, K; Kisaki, M; Nakano, H; Sartori, E; Serianni, G; Takeiri, Y; Tsumori, K

    2016-02-01

    At National Institute for Fusion Science (NIFS), a multi-ampere negative ion source is used to support the R&D on H(-) production, extraction, and acceleration. In this contribution, we study the characteristics of the acceleration system of this source, in order to characterize the beam optics at different operational conditions. A dedicated experimental campaign was carried out at NIFS, using as main diagnostic the infra-red imaging of the beam profiles. The experimental measurements are also compared with 3D numerical simulations, in order to validate the codes and to assess their degree of reliability. The simulations show a satisfactory agreement with the experimental results.

  5. Optics of the NIFS negative ion source test stand by infrared calorimetry and numerical modelling

    Energy Technology Data Exchange (ETDEWEB)

    Veltri, P., E-mail: pierluigi.veltri@igi.cnr.it; Antoni, V.; Agostinetti, P.; Brombin, M.; Sartori, E.; Serianni, G. [Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), Corso Stati Uniti 4, 35127 Padova (Italy); Ikeda, K.; Kisaki, M.; Nakano, H.; Takeiri, Y.; Tsumori, K. [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan)

    2016-02-15

    At National Institute for Fusion Science (NIFS), a multi-ampere negative ion source is used to support the R&D on H{sup −} production, extraction, and acceleration. In this contribution, we study the characteristics of the acceleration system of this source, in order to characterize the beam optics at different operational conditions. A dedicated experimental campaign was carried out at NIFS, using as main diagnostic the infra-red imaging of the beam profiles. The experimental measurements are also compared with 3D numerical simulations, in order to validate the codes and to assess their degree of reliability. The simulations show a satisfactory agreement with the experimental results.

  6. Optics of the NIFS negative ion source test stand by infrared calorimetry and numerical modelling

    Science.gov (United States)

    Veltri, P.; Antoni, V.; Agostinetti, P.; Brombin, M.; Ikeda, K.; Kisaki, M.; Nakano, H.; Sartori, E.; Serianni, G.; Takeiri, Y.; Tsumori, K.

    2016-02-01

    At National Institute for Fusion Science (NIFS), a multi-ampere negative ion source is used to support the R&D on H- production, extraction, and acceleration. In this contribution, we study the characteristics of the acceleration system of this source, in order to characterize the beam optics at different operational conditions. A dedicated experimental campaign was carried out at NIFS, using as main diagnostic the infra-red imaging of the beam profiles. The experimental measurements are also compared with 3D numerical simulations, in order to validate the codes and to assess their degree of reliability. The simulations show a satisfactory agreement with the experimental results.

  7. Heat capacity and transition behavior of sucrose by standard, fast scanning and temperature-modulated calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Magoń, A. [Department of Chemistry, University of Technology, 35-959 Rzeszów (Poland); Wurm, A.; Schick, C. [Department of Physics, University of Rostock, 18057 Rostock (Germany); Pangloli, Ph.; Zivanovic, S. [Department of Food Science and Technology, University of Tennessee, Knoxville, TN 37996 (United States); Skotnicki, M. [Department of Pharmaceutical Technology, Poznan University of Medical Sciences, 60-780 Poznań (Poland); Pyda, M., E-mail: mpyda@utk.edu [Department of Chemistry, University of Technology, 35-959 Rzeszów (Poland)

    2014-08-10

    Highlights: • Experimental, apparent heat capacity of sucrose was investigated by advanced thermal analysis. • Vibrational heat capacity of solid state was linked with a low temperature experimental heat capacity of sucrose. • Equilibrium melting parameters of sucrose were determined. • Decomposition, superheating of crystalline sucrose during melting process were presented. • TGA, DSC, TMDSC, and FSC are useful tools for characterization of sucrose. - Abstract: The heat capacity (C{sub p}) of crystalline and amorphous sucrose was determined using standard and quasi-isothermal temperature modulated differential scanning calorimetry. The results were combined with the published data determined by adiabatic calorimetry, and the C{sub p} values are now reported for the wide 5–600 K range. The experimental C{sub p} of solid sucrose at 5–300 K was used to calculate the vibrational, solid C{sub p} based on the vibrational molecular motions. The calculated solid and liquid C{sub p} together with the transition parameters for equilibrium conditions were used as references for detailed quantitative thermal analysis of crystalline and amorphous sucrose. Melting temperature (T{sub m}) of the crystalline sucrose was identified in a broad 442–465 K range with a heat of fusion of 40–46 J/mol determined at heating rates 0.5–20 K/min, respectively. The equilibrium T{sub m} and heat of fusion of crystalline sucrose were estimated at zero heating rate as T{sup o}{sub m} = 424.4 K and ΔH{sup o}{sub f} = 32 kJ/mol, respectively. The glass transition temperature (T{sub g}) of amorphous sucrose was at 331 K with a change in C{sub p} of 267 J/(mol K) as it was estimated from reversing heat capacity by quasi-isothermal TMDSC on cooling. At heating rates less than 30 K/min, thermal decomposition occurred during melting, while at extreme rate of 1000 K/s, degradation was not observed. Data obtained by fast scanning calorimetry (FSC) at 1000 K/s, showed that T{sub m} was

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

    Science.gov (United States)

    Dubaniewicz, Thomas H; DuCarme, Joseph P

    2016-09-01

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

  9. Use of isothermal titration calorimetry to study the interaction of short-chain alcohols with lipid membranes

    DEFF Research Database (Denmark)

    Trandum, Christa; Westh-Andersen, Peter; Jørgensen, Kent

    1999-01-01

    of short-chain alcohols on Lipid bilayers. isothermal titration calorimetry (ITC) has been used to determine the energy involved in the association of the alcohols with lipid bilayers. Pure unilamellar DMPC liposomes and DMPC liposomes incorporated with different amounts of cholesterol, sphingomyelin...... dependent on the lipid bilayer composition. In the presence of high concentrations of cholesterol, the binding enthalpy of ethanol is decreased, whereas the presence of ceramides enhances the enthalpic response of the lipid bilayer to ethanol. Isothermal titration calorimetry offers a new methodology...

  10. Isothermal titration calorimetry and surface plasmon resonance allow quantifying substrate binding to different binding sites of Bacillus subtilis xylanase

    DEFF Research Database (Denmark)

    Cuyvers, Sven; Dornez, Emmie; Abou Hachem, Maher

    2012-01-01

    Isothermal titration calorimetry and surface plasmon resonance were tested for their ability to study substrate binding to the active site (AS) and to the secondary binding site (SBS) of Bacillus subtilis xylanase A separately. To this end, three enzyme variants were compared. The first was a cat......Isothermal titration calorimetry and surface plasmon resonance were tested for their ability to study substrate binding to the active site (AS) and to the secondary binding site (SBS) of Bacillus subtilis xylanase A separately. To this end, three enzyme variants were compared. The first...

  11. Adsorption and adhesion energies of Pb on (1×1)-Mo2C/Mo(100) by calorimetry

    Science.gov (United States)

    Smedh, M.; Diaz, S. F.; Campbell, C. T.

    2003-05-01

    This paper reports calorimetric measurements of the adsorption energy of Pb onto an ordered 1×1 Mo carbide thin film on Mo(100) at 300 K, as well as measurements of the sticking probability and film growth mode of this system. The heat of adsorption is constant up to a Pb coverage of 0.5 ML, with a value of 244.5±2 kJ/mol. Between 0.5 and 0.9 ML the heat decreases linearly to a value close to the heat of sublimation for bulk Pb, where it remains at higher coverages. The sticking probability increases linearly for submonolayer coverages from an initial value of about 0.97. At coverages above 0.8 0.9 ML it stays constant at 0.994. The growth mode is Stranski-Krastanov, with two-dimensional (2D) growth up to 0.9 ML and 3D island growth thereafter. A growth model, consisting of Pb adatoms not filling nearest neighbor sites up to 0.5 ML and random filling of nearest neighbor sites at higher coverages, provides a very good fit to the calorimetry data. The model involves a 14-kJ/mol Pb-Pb pairwise repulsion at nearest neighbor sites, as well as a 14-kJ/mol relaxation of the repulsion by slight relaxations from the site centers, when not constrained by other Pb nearest neighbors. The adhesion energy, from the integral heat of adsorption for multilayer Pb, is 194±10 μJ/cm2.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-11-13

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

  13. Electromagnetic calorimetry with $PbWO^{4}$ in the energy regime below 1 GeV

    CERN Document Server

    Novotny, R; Döring, W; Hejny, V; Hofstäetter, A; Korzhik, M V; Metag, V; Ströher, H

    2000-01-01

    The study of the performance and application of PbWO/sub 4/ in electromagnetic calorimetry at energies far below 1 GeV has been continued. The significantly improved optical and scintillation properties of 15 cm long Nb/La-doped crystals, optimized for the ECAL /CMS calorimeter, are documented. The lineshape, energy and time response of a 5*5 matrix are tested with monoenergetic photons up to 790 MeV energy and compared to previous measurements. First attempts have been made to enhance the scintillation yield by suitable dopants (Mo, Tb) for applications at very low photon energies. As a first large scale project at medium energies, the proposed concept for a compact photon spectrometer to be implemented into the ANKE magnetic spectrometer at COSY (KFA Julich) is illustrated. (4 refs).

  14. Electromagnetic calorimetry with $PbWO_{4}$ in the energy regime below 1 GeV

    CERN Document Server

    Novotny, R; Döring, W; Hejny, V; Hofstäetter, A; Korzhik, M V; Metag, V; Ströher, H

    1999-01-01

    The study of the performance and application of PbWO/sub 4/ in electromagnetic calorimetry at energies far below 1 GeV has been continued. The significantly improved optical and scintillation properties of 15 cm long Nb/La-doped crystals, optimized for the ECAL /CMS calorimeter, are documented. The lineshape, energy and time response of a 5*5 matrix are tested with monoenergetic photons up to 790 MeV energy and compared to previous measurements. First attempts have been made to enhance the scintillation yield by suitable dopants (Mo, Tb) for applications at very low photon energies. As a first large scale project at medium energies, the proposed concept for a compact photon spectrometer to be implemented into the ANKE magnetic spectrometer at COSY (KFA Julich) is illustrated. (2 refs).

  15. A survey of the year 2002 literature on applications of isothermal titration calorimetry.

    Science.gov (United States)

    Cliff, Matthew J; Ladbury, John E

    2003-01-01

    Isothermal titration calorimetry (ITC) is becoming widely accepted as a key instrument in any laboratory in which quantification of biomolecular interactions is a requisite. The method has matured with respect to general acceptance and application development over recent years. The number of publications on ITC has grown exponentially over the last 10 years, reflecting the general utility of the method. Here all the published works of the year 2002 in this area have been surveyed. We review the broad range of systems to which ITC is being directed and classify these into general areas highlighting key publications of interest. This provides an overview of what can be achieved using this method and what developments are likely to occur in the near future.

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

    Science.gov (United States)

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

    2009-06-01

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

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

    Science.gov (United States)

    Swamy, Musti J; Sankhala, Rajeshwer S

    2013-01-01

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

  18. Direct Coupling of SiPMs to Scintillator Tiles for Imaging Calorimetry and Triggering

    CERN Document Server

    Simon, Frank; Joram, Christian

    2010-01-01

    The recent availability of blue sensitive silicon photomultipliers allows the direct readout of blue emitting plastic scintillator tiles without the use of a wavelength shifting fiber. Such directly read out tiles, without light guides, are attractive for the use in highly granular calorimeters that use large numbers of individual cells and in other applications where very compact designs are needed. However, the total signal amplitude and the uniformity of the response can be problematic in such cases. We have developed a scanning setup to investigate the response of scintillator tiles with SiPM readout in detail. It was used to develop optimized scintillator tile geometries for highly granular hadronic calorimetry at future colliders and to investigate the feasibility of a SiPM readout for the trigger of the ATLAS ALFA luminosity detectors. We report on results obtained with specialized scintillator tile geometries, discuss first results obtained with directly coupled SiPM readout of the ATLAS ALFA trigger ...

  19. Crystallization kinetics in liquid crystals with hexagonal precursor phases by calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Padmaja, Sunkara; Ajita, Narayanan; Potukuchi, Dakshina Murthy [Dept. of Physics, Jawaharlal Nehru Technological Univ., Kakinada (India); Srinivasulu, Maddasani; Girish, Sriram Ramchandra [Liquid Crystal Research Centre, Koneru Lakshmaiah Coll. of Engineering, Vaddeswaram (India); Pisipati, Venkata Gopala Krishna Murthy [Dept. of Chemistry, Manipal Inst. of Tech. (India)

    2010-08-15

    Design and characterization of Schiff based liquid crystalline nO.m compounds exhibiting hexagonal smectic phases are reported. Crystallization kinetics investigations are carried out in the liquid crystals (LCs) exhibiting hexagonal ordered orthogonal and tilted precursor LC phases by calorimetry. The Avrami theory is referred and results are analyzed. Influence of molecular ordering, structure, and dimensionality of the LC precursor phase on kinetics is studied. Effect of shape and flexibility of the molecule for nucleation and growth processes is investigated. Varying rate of kinetics reflects upon the transit of the system from constant type to independent type of nucleation. The trends in the Avrami parameter b and exponent n suggest sporadic nucleation. Crystal growth is interpreted as heterogeneous permeation of layered domains (or aggregates) formed by needle shaped calamitic molecules. Calorimetric observations at different crystallization temperatures CT and hold time t infer diffusion mediated crystallization. (orig.)

  20. From calorimetry to medical imaging: a shining example of successful transfer!

    CERN Multimedia

    Caroline Duc

    2012-01-01

    A team at CERN has drawn inspiration from calorimetry methods developed for high-energy physics to create a new positron-emission tomography system for use in medical imaging, which they’ve dubbed AX-PET. With support from European and American laboratories*, the project is reaching fruition, as initial tests confirm its promise.   Snapshot of a “phantom”, a test object, surrounded by the AX-PET photon detectors. Positron-emission tomography (PET) is a medical imaging technique based on the matter-antimatter interaction that can provide a three-dimensional representation of the metabolic activity of an organ. To do so, radioactive marker molecules are first injected into the subject. As the marker decays, it emits positrons (antimatter particles), which are annihilated upon encountering electrons in the surrounding environment. The resulting flash, consisting of two photons, is detected by the PET machine. In conventional PET systems, it is impossible to improv...

  1. Kinetics of Enzymatic High-Solid Hydrolysis of Lignocellulosic Biomass Studied by Calorimetry

    DEFF Research Database (Denmark)

    Olsen, Søren Nymand; Rasmussen, Erik Lumby; McFarland, K.C.;

    2011-01-01

    Enzymatic hydrolysis of high-solid biomass (>10% w/w dry mass) has become increasingly important as a key step in the production of second-generation bioethanol. To this end, development of quantitative real-time assays is desirable both for empirical optimization and for detailed kinetic analysis....... In the current work, we have investigated the application of isothermal calorimetry to study the kinetics of enzymatic hydrolysis of two substrates (pretreated corn stover and Avicel) at high-solid contents (up to 29% w/w). It was found that the calorimetric heat flow provided a true measure of the hydrolysis...... 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 (

  2. Toward New High Temperature Reference Materials for Calorimetry and Thermal Analysis

    Directory of Open Access Journals (Sweden)

    Razouk R.

    2014-01-01

    Full Text Available 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.

  3. A digital Front-End and Readout MIcrosystem for calorimetry at LHC

    CERN Multimedia

    2002-01-01

    % RD-16 A Digital Front-End and Readout Microsystem for Calorimetry at LHC \\\\ \\\\Front-end signal processing for calorimetric detectors is essential in order to achieve adequate selectivity in the trigger function of an LHC experiment, with data identification and compaction before readout being required in the harsh, high rate environment of a high luminosity hadron machine. Other crucial considerations are the extremely wide dynamic range and bandwidth requirements, as well as the volume of data to be transferred to following stages of the trigger and readout system. These requirements are best met by an early digitalization of the detector information, followed by integrated digital signal processing and buffering functions covering the trigger latencies.\\\\ \\\\The FERMI (Front-End Readout MIcrosystem) is a digital implementation of the front-end and readout electronic chain for calorimeters. It is based on dynamic range compression, high speed A to D converters, a fully programmable pipeline/digital filter c...

  4. Building a graphite calorimetry system for the dosimetry of therapeutic x-ray beams

    Energy Technology Data Exchange (ETDEWEB)

    Kim, In Jung; Kim, Byoung Chul; Kim, Joong Hyun; Chung, Jae Pil; Kim, Hyun Moon; Yi, Chul Young [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of)

    2017-06-15

    A graphite calorimetry system was built and tested under irradiation. The noise level of the temperature measurement system was approximately 0.08 mK (peak to peak). The temperature of the core part rose by approximately 8.6 mK at 800 MU (monitor unit) for 6-MV X-ray beams, and it increased as X-ray energy increased. The temperature rise showed less spread when it was normalized to the accumulated charge, as measured by an external monitoring chamber. The radiation energy absorbed by the core part was determined to have values of 0.798 J/μC, 0.389 J/μC, and 0.352 J/μC at 6 MV, 10 MV, and 18 MV, respectively. These values were so consistent among repeated runs that their coefficient of variance was less than 0.15%.

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

    Science.gov (United States)

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

    2015-06-04

    Substrate binding properties of the large (LS) and small (SS) subunits of potato tuber ADP-glucose pyrophosphorylase were investigated by using isothermal titration calorimetry. Our results clearly show that the wild type heterotetramer (S(WT)L(WT)) possesses two distinct types of ATP binding sites, whereas the homotetrameric LS and SS variant forms only exhibited properties of one of the two binding sites. The wild type enzyme also exhibited significantly increased affinity to this substrate compared to the homotetrameric enzyme forms. No stable binding was evident for the second substrate, glucose-1-phosphate, in the presence or absence of ATPγS suggesting that interaction of glucose-1-phosphate is dependent on hydrolysis of ATP and supports the Theorell-Chance bi bi reaction mechanism. Copyright © 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  6. Ln(III)-malate complexation studies using TRLFS and micro titration calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Taube, F.; Drobot, B. [Technische Univ. Dresden (Germany). Professorship Radiochemistry; Acker, M.; Taut, S. [Technische Univ. Dresden (Germany). Central Radionuclide Laboratory; Stumpf, Thorsten [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Inst. of Resource Ecology

    2017-06-01

    The complexation of trivalent lanthanides was studied using Time-Resolved Laser-Induced Fluorescence Spectroscopy (TRLFS) and Isothermal Titration Calorimetry (ITC). Formation constants, complexation enthalpies and fluorescence lifetimes are determined over a wide pH range at I = 0.5 m NaCl. This subject has the following background: Concrete is widely used as engineering barrier and for waste conditioning in waste repositories. Its binding agent is cement. Organic cement additives, which are used to improve the workability of fresh concrete, are complexation agents for radionuclides after they have been released during the concretes degradation. Thus, these additives might have an impact on the aqueous geochemistry of actinides. Here, the α-hydroxydicarboxylic acid or malic acid is examined. It is used in water-reducers or retarders in cement.

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

    Science.gov (United States)

    Rohatgi, Neha; Guðmundsson, Steinn; Rolfsson, Óttar

    2015-11-30

    Gluconate is a commonly encountered nutrient, which is degraded by the enzyme gluconokinase to generate 6-phosphogluconate. Here we used isothermal titration calorimetry to study the properties of this reaction. ΔH, KM and kcat are reported along with substrate binding data. We propose that the reaction follows a ternary complex mechanism, with ATP binding first. The reaction is inhibited by gluconate, as it binds to an Enzyme-ADP complex forming a dead-end complex. The study exemplifies that ITC can be used to determine mechanisms of enzyme catalyzed reactions, for which it is currently not commonly applied. Copyright © 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  8. Cooling rate dependence of undercooling of pure Sn single drop by fast scanning calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Bin [Shanghai University, Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai (China); University of Rostock, Institute of Physics, Rostock (Germany); Gao, Yulai; Zou, Changdong; Zhai, Qijie [Shanghai University, Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai (China); Abyzov, A.S. [Kharkov Institute of Physics and Technology, National Science Center, Kharkov (Ukraine); Zhuravlev, E.; Schmelzer, J.W.P.; Schick, C. [University of Rostock, Institute of Physics, Rostock (Germany)

    2011-07-15

    Non-adiabatic fast scanning calorimetry has been developed to in-situ measure the response of single metallic drops to temperature changes in a large range of cooling rate spanning four orders of magnitude. In particular, the effect of cooling rate on the degree of undercooling of one 10 {mu}m Sn-drop is studied. The experimental results show that the undercooling could be increased first significantly with increasing cooling rate going over to a stage of slow increase for high cooling rates, which indicates a shelf-like dependence of undercooling level on cooling rate before and after a ''crossover'' at a cooling rate of about 1000 K/s where two different heterogeneous mechanisms act simultaneously. First theoretical estimates are developed on the specific feature of the heterogeneous nucleation process of the effect analyzed and possible directions of further research are anticipated. (orig.)

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

    Energy Technology Data Exchange (ETDEWEB)

    Coker, Eric Nicholas

    2013-10-01

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

  10. Electrospray techniques for the study of liquid energetics by hyperquenched glass calorimetry

    CERN Document Server

    Wang, L M; Angell, C A; Wang, Li-Min; Borick, Steve

    2002-01-01

    We describe an electrospray technique for in situ preparation, for differential scanning calorimetry study, of samples of molecular liquids quenched into the glassy state on extremely short time scales (hyperquenched). We study the case of propylene glycol PG in some detail. Using a fictive temperature method of obtaining the temperature dependence of enthalpy relaxation, we show that the electrospray method yields quenching rates of ~105 K/s, while the more common method, dropping a sealed pan of sample into liquid nitrogen, yields only 120 K/s. Hyperquenched samples start to relax exothermically far below the glass temperature, at a temperature where the thermal energy permits escape from the shallow traps in which the system becomes localized during hyperquenching. This permits estimation of the trap depths, which are then compared with the activation energy estimated from the fictive temperature of the glass and the relaxation time at the fictive temperature. The trap depth in molar energy units is compar...

  11. Granulometric structure, zeta potential and differential scanning calorimetry of native starch powders from Dioscorea spp.

    Directory of Open Access Journals (Sweden)

    Gildas K. Gbassi

    2014-07-01

    Full Text Available Starch powders from two cultivars of Dioscorea rotundata (DR were analysed on the physicochemical aspect. Granulometric structure, zeta potential and differential scanning calorimetry of starch powders showed the following properties. Various shapes with predominance of granule ranging from 10 to 40 μm were noted. The zeta potential of DR went from positive values to negative values as the pH was increasing from 2 to 8. From pH 2 to 4, the zeta potential was positive. A significant difference was obtained between each value (p > 0.05. The zeta potential took a negative value from pH 5 and above. The results of thermal analysis show that starches start swelling at 68.91.5 C. Enthalpy of gelatinization was about 15 J.g-1 .

  12. Steady State Condition in the Measurement of VO2and VCO2by Indirect Calorimetry.

    Science.gov (United States)

    Cadena, M; Sacristan, E; Infante, O; Escalante, B; Rodriguez, F

    2005-01-01

    Resting Metabolic Rate (RMR) is computed using VO2and VCO2short time 15-minute window measurement with Indirect Calorimetry (IC) instruments designed with mixing chamber. Steady state condition using a 10% variation coefficient criteria is the main objective to achieve metabolic long time prediction reliability. This study address how susceptible is the steady state VO2, VCO2measurement condition to the clino-orthostatic physiological maneuver. 30 young healthy subjects were analyzed. Only 18 passed the 10% variation coefficient inclusive criteria. They were exposed to 10 minutes clino-stage and 10 minutes orthostage. The hypothesis tests show not statistical significance (p< 0.1) in the average and variance analysis. It is concluded that the steady state is not influenced by the patient position IC test, probably because IC mixing chamber instruments are insensitive to detect a mayor physiological dynamics changes that can modify the steady state definition.

  13. Conformation and stability properties of B17: II. Analytical investigations using differential scanning calorimetry.

    Science.gov (United States)

    Khachfe, Hassan M; Atkinson, David

    2013-04-01

    Thermal and stability properties of B17, the 17% N-terminal domain of apo B, were carried out using differential scanning calorimetry spectroscopy, where the thermal characteristics of the polypeptide were studied and analyzed. The heat capacity data of B17 showed that the protein undergoes two transitions between 50 and 90 °C, with T m's at 65.9 and 74.8 °C. While the first transition showed immediate reversibility, the second one-with the higher T m-necessitated a longer cooling (several days) period for its reversibility to be observed and both transitions could be seen in the heat capacity profile of B17. Moreover, the van't Hoff enthalpies determined via calorimetric measurements agreed with the values calculated from the CD analysis reported previously.

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

    Science.gov (United States)

    Cieśla, Krystyna; Eliasson, Ann-Charlotte

    2002-05-01

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

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

    Science.gov (United States)

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

    2012-08-01

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

  16. CZECHOSLOVAK FOOTPRINTS IN THE DEVELOPMENT OF METHODS OF THERMOMETRY, CALORIMETRY AND THERMAL ANALYSIS

    Directory of Open Access Journals (Sweden)

    Pavel Holba

    2012-07-01

    Full Text Available A short history on the development of thermometric methods are reviewed accentuating the role of Rudolf Bárta in underpinning special thermoanalytical conferences and new journal Silikáty in fifties as well as Vladimir Šatava mentioning his duty in the creation of the Czech school on thermoanalytical kinetics. This review surveys the innovative papers dealing with thermal analysis and the related fields (e.g. calorimetry, kinetics which have been published by noteworthy postwar Czechoslovak scholars and scientists and by their disciples in 1950-1980. Itemized 227 references with titles show rich scientific productivity revealing that many of them were ahead of time even at international connotation.

  17. Van’t Hoff global analyses of variable temperature isothermal titration calorimetry data

    Science.gov (United States)

    Freiburger, Lee A.; Auclair, Karine; Mittermaier, Anthony K.

    2016-01-01

    Isothermal titration calorimetry (ITC) can provide detailed information on the thermodynamics of biomolecular interactions in the form of equilibrium constants, KA, and enthalpy changes, ΔHA. A powerful application of this technique involves analyzing the temperature dependences of ITC-derived KA and ΔHA values to gain insight into thermodynamic linkage between binding and additional equilibria, such as protein folding. We recently developed a general method for global analysis of variable temperature ITC data that significantly improves the accuracy of extracted thermodynamic parameters and requires no prior knowledge of the coupled equilibria. Here we report detailed validation of this method using Monte Carlo simulations and an application to study coupled folding and binding in an aminoglycoside acetyltransferase enzyme. PMID:28018008

  18. Determination of Energy Characteristic and Microporous Volume by Immersion Calorimetry in Carbon Monoliths

    Directory of Open Access Journals (Sweden)

    Juan Carlos Moreno-Piraján

    2012-01-01

    Full Text Available Activated carbon monoliths disc and honeycomb type were prepared by chemical activation of coconut shell with zinc chloride at different concentrations, without using a binder. The structures were characterized by N2 adsorption at 77 K and immersion calorimetry into benzene. The experimental results showed that the activation with zinc chloride produces a wide microporous development, with micropore volume between 0,38 and 0,79 cm3g-1, apparent BET surface area between 725 and 1523 m2g-1 and immersion enthalpy between 73,5 and 164,2 Jg-1. We compared the experimental enthalpy with calculated enthalpy by equation Stoeckli-Kraehenbuehl finding a data dispersion from which can infer that the structures are not purely microporous; this fact is ratified with similar behavior that the evidence t the product EoWo.

  19. DETERMINATION OF HYDROGEN DESORBED THROUGH THERMAL CALORIMETRY IN A HIGH STRENGTH STEEL

    Directory of Open Access Journals (Sweden)

    Carolina A. Asmus

    2014-03-01

    Full Text Available The following study aims to quantify the release activation energy (Ea of hydrogen (H from lattice sites, reversible or irreversible, where the H can be trapped. Moreover, enthalpy changes associated with the main hydrogen (H trapping sites can be analyzed by means of differential scanning calorimetry (DSC. In this technique, the peak temperature measurement is determined at two different heating rates, 3ºC/min y 5ºC/min, from ambient temperature to 500°C. In order to simulate severe conditions of hydrogen income into resulfurized high strength steel, electrolytic permeation tests were performed on test tubes suitable for fatigue tests. Sometimes during charging, H promoters were aggregated to electrolytic solution. Subsequently, the test tubes were subjected to flow cycle fatigue tests. Finally, irreversible trap which anchor more strongly H atoms are MnS inclusions. Its role on hydrogen embrittlement during fatigue tests is conclusive.

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

    Science.gov (United States)

    Quittnat, Milena; CMS Collaboration

    2015-02-01

    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.

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

    CERN Document Server

    Quittnat, Milena Eleonore

    2015-01-01

    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 measu...

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

    Energy Technology Data Exchange (ETDEWEB)

    Ciesla, Krystyna E-mail: kciesla@orange.ichtj.waw.pl; Eliasson, A.-C

    2002-05-01

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

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

    Science.gov (United States)

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

    2013-11-01

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

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

    Science.gov (United States)

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

    2010-01-01

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

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

    Science.gov (United States)

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

    2014-12-01

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

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

    Science.gov (United States)

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

    2016-05-01

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

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

    Science.gov (United States)

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

    2010-01-01

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

  8. Resolving glass transition in Te-based phase-change materials by modulated differential scanning calorimetry

    Science.gov (United States)

    Chen, Yimin; Mu, Sen; Wang, Guoxiang; Shen, Xiang; Wang, Junqiang; Dai, Shixun; Xu, Tiefeng; Nie, Qiuhua; Wang, Rongping

    2017-10-01

    Glass transitions of Te-based phase-change materials (PCMs) were studied by modulated differential scanning calorimetry. It was found that both Ge2Sb2Te5 and GeTe are marginal glass formers with ΔT (= T x ‑ T g) less than 2.1 °C when the heating rate is below 3 °C min‑1. The fragilities of Ge2Sb2Te5 and GeTe can be estimated as 46.0 and 39.7, respectively, around the glass transition temperature, implying that a fragile-to-strong transition would be presented in such Te-based PCMs. The above results provide direct experimental evidence to support the investigation of crystallization kinetics in supercooled liquid PCMs.

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

    Science.gov (United States)

    Rager, Timo

    2014-06-01

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

  10. Research and Development for the ATLAS Forward Calorimetry at the HL-LHC

    CERN Document Server

    Cheplakov, Alexander

    2015-01-01

    A total luminosity of 3000/fb is expected at the HL-LHC, which corresponds to total irradiation doses which are more than doubled compared to the original design, taking into account a safety factor of 2 representing our confidence in radiation background simulations. Moreover, the increased instantaneous luminosity will result in a much higher detector occupancy. The ATLAS Forward Calorimeters (FCal) will be affected by these factors. A rich R&D program is ongoing to evaluate the consequences of the LHC modernization and to investigate di_erent scenarios proposed for the Phase-II detector upgrade. This contribution will concentrate on simulation studies of the FCal degradation and on irradiation tests performed at the IBR-2m reactor in Dubna. Results from radiation-tolerant sensors and components of the future read-out and voltage distribution system for various upgrade options of the forward calorimetry will be presented.

  11. Stability of some Cactaceae proteins based on fluorescence, circular dichroism, and differential scanning calorimetry measurements.

    Science.gov (United States)

    Gorinstein, S; Zemser, M; Vargas-Albores, F; Ochoa, J L; Paredes-Lopez, O; Scheler, C; Aksu, S; Salnikow, J

    1999-02-01

    Characterization of three cactus proteins (native and denatured) from Machaerocereus gummosus (Pitahaya agria), Lophocereu schottii (Garambullo), and Cholla opuntia (Cholla), was based on electrophoretic, fluorescence, CD (circular dichroism), DSC (differential scanning calorimetry), and FT-IR (Fourier transform infrared) measurements. The obtained results of intrinsic fluorescence, DSC, and CD were dissimilar for the three species of cactus, providing evidence of differences in secondary and tertiary structures. Cactus proteins may be situated in the following order corresponding to their relative stability: Machaerocereus gummosus (Pitahaya agria) > Cholla opuntia (Cholla) > Lophocereu schottii (Garambullo). Thermodynamic properties of proteins and their changes upon denaturation (temperature of denaturation, enthalphy, and the number of ruptured hydrogen bonds) were correlated with the secondary structure of proteins and disappearance of alpha-helix.

  12. Design and First Measurements of an Alternative Calorimetry Chamber for the HZB Quadrupole Resonator

    CERN Document Server

    Keckert, Sebastian; Knobloch, Jens; Kugeler, Oliver

    2015-01-01

    The systematic research on superconducting thin films requires dedicated testing equipment. The Quadrupole Resonator (QPR) is a specialized tool to characterize the superconducting RF properties of circular planar samples. A calorimetric measurement of the RF surface losses allows the surface resistance to be measured with sub nano-ohm resolution. This measurement can be performed over a wide temperature and magnetic field range, at frequencies of 433, 866 and 1300 MHz. The system at Helmholtz-Zentrum Berlin (HZB) is based on a resonator built at CERN and has been optimized to lower peak electric fields and an improved resolution. In this paper the design of an alternative calorimetry chamber is presented, providing flat samples for coating which are easy changeable. All parts are connected by screwing connections and no electron beam welding is required. Furthermore this design enables exchangeability of samples between the resonators at HZB and CERN. First measurements with the new design show ambiguous r...

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

    Science.gov (United States)

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

    2012-01-01

    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.

  14. Determination of the aggregation number for micelles by isothermal titration calorimetry

    DEFF Research Database (Denmark)

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

    2014-01-01

    Isothermal titration calorimetry (ITC) has previously been applied to estimate the aggregation number (n), Gibbs free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) of micellization. However, some difficulties of micelle characterization by ITC still remain; most micelles have aggregation numbers...... > 4 and its mathematical implementation is therefore not straight-forward. It seems as if all of these difficulties can be traced back to the aggregation number. In this work a new principle of data quantification is derived which is easy to apply, interpret and will provide statistical reliable...... insight into optimal design of titration protocols for micelle characterization. By applying the new method, the aggregation number of sodium dodecyl sulphate and glycochenodeoxycholate was determined at concentrations around their critical micelle concentration (CMC)...

  15. Efficient Isothermal Titration Calorimetry Technique Identifies Direct Interaction of Small Molecule Inhibitors with the Target Protein.

    Science.gov (United States)

    Gal, Maayan; Bloch, Itai; Shechter, Nelia; Romanenko, Olga; Shir, Ofer M

    2016-01-01

    Protein-protein interactions (PPI) play a critical role in regulating many cellular processes. Finding novel PPI inhibitors that interfere with specific binding of two proteins is considered a great challenge, mainly due to the complexity involved in characterizing multi-molecular systems and limited understanding of the physical principles governing PPIs. Here we show that the combination of virtual screening techniques, which are capable of filtering a large library of potential small molecule inhibitors, and a unique secondary screening by isothermal titration calorimetry, a label-free method capable of observing direct interactions, is an efficient tool for finding such an inhibitor. In this study we applied this strategy in a search for a small molecule capable of interfering with the interaction of the tumor-suppressor p53 and the E3-ligase MDM2. We virtually screened a library of 15 million small molecules that were filtered to a final set of 80 virtual hits. Our in vitro experimental assay, designed to validate the activity of mixtures of compounds by isothermal titration calorimetry, was used to identify an active molecule against MDM2. At the end of the process the small molecule (4S,7R)-4-(4-chlorophenyl)-5-hydroxy-2,7-dimethyl-N-(6-methylpyridin-2-yl)-4,6,7,8 tetrahydrIoquinoline-3-carboxamide was found to bind MDM2 with a dissociation constant of ~2 µM. Following the identification of this single bioactive compound, spectroscopic measurements were used to further characterize the interaction of the small molecule with the target protein. 2D NMR spectroscopy was used to map the binding region of the small molecule, and fluorescence polarization measurement confirmed that it indeed competes with p53.

  16. Differential scanning calorimetry and reaction kinetics studies of {gamma} + {alpha}{sub 2} Ti aluminide

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, R.K., E-mail: rohitkumar_gupta@vssc.gov.in [Vikram Sarabhai Space Centre, ISRO, Trivandrum 695 022 (India); Pant, Bhanu [Vikram Sarabhai Space Centre, ISRO, Trivandrum 695 022 (India); Agarwala, Vijaya [Indian Institute of Technology Roorkee, Roorkee 247 667 (India); Sinha, P.P. [Vikram Sarabhai Space Centre, ISRO, Trivandrum 695 022 (India)

    2012-12-14

    Reaction synthesis method for titanium aluminide processing consists of an exothermic reaction among alloying elements present and primarily between titanium and aluminium particles at specific temperature range. Study of this reaction helps in understanding the process of aluminide formation. Differential scanning calorimetry (DSC) study is the suitable method to study such reactions. In the present work, five different alloy mixtures based on Ti48Al2Cr2Nb0.1B are prepared and DSC study is carried out. Onset temperature, peak temperature and completion temperature of the major exothermic reaction is analyzed at different heating rates. Further, kinetics of the reaction is studied using Johnson-Mehl-Avrami equation. Activation energy and Avrami parameter are calculated and compared with the reported works on binary alloy. It has been observed that exothermic reaction is triggered by melting of aluminium. Boron assists in increasing the enthalpy of reaction by boride formation. Primary reaction product is found to be TiAl{sub 3}. Activation energy as well as Avrami parameter is found to have marginal variation due to small change in alloying elements in different alloys and due to heating rates in the same alloy. -- Highlights: Black-Right-Pointing-Pointer Reaction kinetics studies of Ti-aluminide alloy powder mixtures carried out. Black-Right-Pointing-Pointer Five compositions studied through non-isothermal differential scanning calorimetry. Black-Right-Pointing-Pointer Effect of minor boron addition and role of Ti particle size is noted. Black-Right-Pointing-Pointer Activation energies using JMA equations are between 169.5 and 192.49 kJ mol{sup -1}.

  17. Comparison of Indirect Calorimetry and Predictive Equations in Estimating Resting Metabolic Rate in Underweight Females

    Directory of Open Access Journals (Sweden)

    Soghra ALIASGHARZADEH

    2015-10-01

    Full Text Available Background: Underweight as a public health problem in young women is associated with nutritional deficiencies, menstrual irregularity, eating disorders, reduced fertility, etc. Since resting metabolic rate (RMR is a necessary compo-nent in the development of nutrition support therapy, therefore we determined the accuracy of commonly used pre-dictive equations against RMR measured by indirect calorimetry among healthy young underweight females.Methods: This cross-sectional study was conducted on 104 underweight females aged 18-30 years old with body mass index (BMI <18.5 kg/m2 in 2013 . After collecting anthropometric data, body composition was measured by bioelec-tric impedance analysis (BIA. RMR was measured by using indirect calorimetry (FitMate™ and was estimated by 10 commonly used predictive equations. Comparisons were conducted using paired t-test. The accuracy of the RMR equations was evaluated on the basis of the percentage of subjects’ predicted RMR within 10% of measured RMR.Results: The mean BMI of subjects was 17.3±1.3 kg/m2. The measured RMR ranged 736-1490 kcal/day (mean 1084.7±175 kcal/day. Findings indicated that except Muller and Abbreviation, other equations significantly over es-timated RMR, compared to measured value (P<0.05. As an individual prediction accuracy, these predictive equations showed poor performance with the highest accuracy rate of 54.8% for Muller equation (22.1% under and 23.1% over-prediction and 43.3% for Abbreviation equation (31.7% under and 25% over-prediction, the percentage bias was 1.8% and 0.63% and RMSE was 162 and 173 kcal/d, respectively.Conclusion: Although Muller equation gave fairly acceptable prediction, more suitable new equations are needed to be developed to help better management of nutritional plans in young underweight people.

  18. Fluence correction factor for graphite calorimetry in a clinical high-energy carbon-ion beam

    Science.gov (United States)

    Lourenço, A.; Thomas, R.; Homer, M.; Bouchard, H.; Rossomme, S.; Renaud, J.; Kanai, T.; Royle, G.; Palmans, H.

    2017-04-01

    The aim of this work is to develop and adapt a formalism to determine absorbed dose to water from graphite calorimetry measurements in carbon-ion beams. Fluence correction factors, {{k}\\text{fl}} , needed when using a graphite calorimeter to derive dose to water, were determined in a clinical high-energy carbon-ion beam. Measurements were performed in a 290 MeV/n carbon-ion beam with a field size of 11  ×  11 cm2, without modulation. In order to sample the beam, a plane-parallel Roos ionization chamber was chosen for its small collecting volume in comparison with the field size. Experimental information on fluence corrections was obtained from depth-dose measurements in water. This procedure was repeated with graphite plates in front of the water phantom. Fluence corrections were also obtained with Monte Carlo simulations through the implementation of three methods based on (i) the fluence distributions differential in energy, (ii) a ratio of calculated doses in water and graphite at equivalent depths and (iii) simulations of the experimental setup. The {{k}\\text{fl}} term increased in depth from 1.00 at the entrance toward 1.02 at a depth near the Bragg peak, and the average difference between experimental and numerical simulations was about 0.13%. Compared to proton beams, there was no reduction of the {{k}\\text{fl}} due to alpha particles because the secondary particle spectrum is dominated by projectile fragmentation. By developing a practical dose conversion technique, this work contributes to improving the determination of absolute dose to water from graphite calorimetry in carbon-ion beams.

  19. Chemical genetics and drug screening in Drosophila cancer models

    Institute of Scientific and Technical Information of China (English)

    Mara Gladstone; Tin Tin Su

    2011-01-01

    Drug candidates often fail in preclinical and clinical testing because of reasons of efficacy and/or safety.It would be time- and cost-efficient to have screening models that reduce the rate of such false positive candidates that appear promising at first but fail later.In this regard,it would be particularly useful to have a rapid and inexpensive whole animal model that can pre-select hits from high-throughput screens but before testing in costly rodent assays.Drosophila melanogaster has emerged as a potential whole animal model for drug screening.Of particular interest have been drugs that must act in the context of multi-cellularity such as those for neurological disorders and cancer.A recent review provides a comprehensive summary of drug screening in Drosophila,but with an emphasis on neurodegenerative disorders.Here,we review Drosophila screens in the literature aimed at cancer therapeutics.

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

    Science.gov (United States)

    Arena, Giuseppe; Gans, Peter; Sgarlata, Carmelo

    2016-09-01

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

  1. Capillary Condensation, Freezing, and Melting in Silica Nanopores: A Sorption Isotherm and Scanning Calorimetry Study on Nitrogen in Mesoporous SBA-15

    CERN Document Server

    Moerz, Sebastian T; Huber, Patrick; 10.1103/PhysRevB.85.075403

    2012-01-01

    Condensation, melting and freezing of nitrogen in a powder of mesoporous silica grains (SBA-15) has been studied by combined volumetric sorption isotherm and scanning calorimetry measurements. Within the mean field model of Saam and Cole for vapor condensation in cylindrical pores a liquid nitrogen sorption isotherm is well described by a bimodal pore radius distribution. It encompasses a narrow peak centered at 3.3 nm, typical of tubular mesopores, and a significantly broader peak characteristic of micropores, located at 1 nm. The material condensed in the micropores as well as the first two adsorbed monolayers in the mesopores do not exhibit any caloric anomaly. The solidification and melting transformation affects only the pore condensate beyond approx. the second monolayer of the mesopores. Here, interfacial melting leads to a single peak in the specific heat measurements. Homogeneous and heterogeneous freezing along with a delayering transition for partial fillings of the mesopores result in a caloric fr...

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

    Science.gov (United States)

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

    2016-12-01

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

  3. Experimental determination of the (vapor + liquid) equilibrium data of binary mixtures of fatty acids by differential scanning calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Matricarde Falleiro, Rafael M. [LPT, Department of Chemical Processes (DPQ), School of Chemical Engineering, University of Campinas (UNICAMP), P.O. Box 6066, 13083-970 Campinas, SP (Brazil); Meirelles, Antonio J.A. [EXTRAE, Department of Food Engineering (DEA), School of Food Engineering, University of Campinas (UNICAMP), P.O. Box 6121, 13083-862 Campinas, SP (Brazil); Kraehenbuehl, Maria A., E-mail: mak@feq.unicamp.b [LPT, Department of Chemical Processes (DPQ), School of Chemical Engineering, University of Campinas (UNICAMP), P.O. Box 6066, 13083-970 Campinas, SP (Brazil)

    2010-01-15

    (Vapor + liquid) equilibrium (VLE) data for three binary mixtures of saturated fatty acids were obtained by differential scanning calorimetry (DSC). However, changes in the calorimeter pressure cell and the use of hermetic pans with holes (phi = 250 mm) in the lids were necessary to make it possible to apply this analytical technique, obtaining accurate results with smaller samples and shorter operational times. The systems evaluated in this study were: myristic acid (C{sub 14:0}) + palmitic acid (C{sub 16:0}), myristic acid (C{sub 14:0}) + stearic acid (C{sub 18:0}), and palmitic acid (C{sub 16:0}) + stearic acid (C{sub 18:0}), all measured at 50 mm Hg and with mole fractions between 0.0 and 1.0 in relation to the most volatile component of each diagram. The fugacity coefficients for the components in the vapor phase were calculated using the Hayden and O'Connell method [J.G. Hayden, J.P. O'Connell, Ind. Eng. Chem. Process Design Develop. 14 (3) (1975) 209-216] and the activity coefficients for the liquid phase were correlated with the traditional g{sup E} models (NRTL [H. Renon, J.M. Prausnitz, Aiche J. 14 (1968) 135-144], UNIQUAC [D.S. Abrams, J.M. Prausnitz, Aiche J. 21 (1975) 116-128], and Wilson [J.M. Prausnitz, N.L. Linchtenthaler, E.G. Azevedo, Molecular Thermodynamics of Fluid-phase Equilibria, River-Prentice Hall, Upper Saddle, 1999]). The sets of parameters were then compared in order to determine which adjustments best represented the VLE.

  4. Photoacoustic calorimetry studies of CO photo-dissociation from chloramine-T modified horse heart cytochrome-c.

    Science.gov (United States)

    Word, Tarah A; Larsen, Randy W

    2016-12-15

    Treatment of horse heart Cytochrome-c (Cc) with N-chloro-4-toluosulfonamide (Chloramine-t, CT) results in the oxidation of methionine (Met) residues to the corresponding sulfoxide including the distal heme ligand, Met80. The resulting Fe-sulfoxide coordination is sufficiently labile in the ferrous form to be displaced by gaseous ligands, including CO. Photolysis of the CO-CT-Cc complex provides an opportunity to examine ligand binding dynamics that are associated with a relatively rigid distal heme pocket. In this work, photoacoustic calorimetry (PAC) was utilized to obtain the kinetics as well as enthalpy and molar volume changes subsequent to CO photo-dissociation from CO-CT-Cc. Previous photolysis studies of CO-CT-Cc have led to a proposed model for ligand recombination in which the Met80-sulfoxide and CO recombine with the heme on relatively slow timescales (50 μs and ∼500 μs, respectively). The PAC data presented here reveals two additional kinetic phases with lifetimes of <20 ns and 534 ± 75 ns. The fast phase (<20 ns) is associated with an ΔH of 44 ± 5 kcal mol(-1) and ΔV of -0.5 ± 0.5 mL mol(-1), whereas the slower phase (534 ns) is associated with a small ΔH of 2 ± 3 kcal mol(-1) and ΔV of 1 ± 0.5 mL mol(-1). Copyright © 2016 Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

    Limo, Marion J; Perry, Carole C

    2015-06-23

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

  6. Versatile peroxidase degradation of humic substances: use of isothermal titration calorimetry to assess kinetics, and applications to industrial wastes.

    Science.gov (United States)

    Siddiqui, Khawar Sohail; Ertan, Haluk; Charlton, Timothy; Poljak, Anne; Daud Khaled, A K; Yang, Xuexia; Marshall, Gavin; Cavicchioli, Ricardo

    2014-05-20

    The kinetic constants of a hybrid versatile-peroxidase (VP) which oxidizes complex polymeric humic substances (HS) derived from lignin (humic and fulvic acids) and industrial wastes were determined for the first time using isothermal titration calorimetry (iTC). The reaction conditions were manipulated to enable manganese-peroxidase (MnP) and/or lignin-peroxidase (LiP) activities to be evaluated. The peroxidase reactions exhibited varying degrees of product inhibition or activation; properties which have not previously been reported for VP enzymes. In contrast to previous work (Ertan et al., 2012) on small non-polymeric substrates (MnSO4, veratryl alcohol and dyes), all kinetic plots for polymeric HS were sigmoidal, lacked Michaelis-Menten characteristics, and were indicative of positive cooperativity. Under conditions when both LiP and MnP were active, the kinetic data fitted to a novel biphasic Hill Equation, and the rate of enzymatic reaction was significantly greater than the sum of individual LiP plus MnP activities implying synergistic activation. By employing size-exclusion chromatography and electrospray ionization mass spectrometry, the characteristics of the oxidative degradation products of the HS were also monitored. Our study showed that the allosteric behaviour of the VP enzyme promotes a high level of regulation of activity during the breakdown of model and industrial ligninolytic substrates. The work was extended to examine the kinetics of breakdown of industrial wastes (effluent from a pulp and paper plant, and fouled membrane solids extracted from a ground water treatment membrane) revealing unique, VP-mediated, kinetic responses. This work demonstrates that iTC can be successfully employed to study the kinetic properties of VP enzymes in order to devise reaction conditions optimized for oxidative degradation of HS present in materials used in a wide range of industries. Crown Copyright © 2014. Published by Elsevier B.V. All rights reserved.

  7. Assessment of the Dissociation Energetics of Some Selected Ligand Drugs Bound on Human Serum Albumin by Differential Scanning Calorimetry.

    Science.gov (United States)

    Faroongsarng, Damrongsak

    2016-04-01

    Drug-protein binding may play a role in the thermal energetics of protein denaturation and could lead to the determination of its equilibrium dissociation parameter. The aim of this study was to assess the energetics of a drug that was bound to human serum albumin (HSA) during thermal denaturation. Drugs that were bound at a single high-affinity primary binding site on HSA, including diazepam and ibuprofen, were employed. Commercial HSA was treated with charcoal to remove stabilizers and adjusted to 20% w/v in a pH 7.4 buffered solution. Serial concentrations of individual drugs up to 0.16 mmole/g-protein were added to the cleaned HSA solutions whereas diazepam was added to a commercial HSA solution. Samples were subjected to differential scanning calorimetry (DSC) set to run from 37 to 90°C at 3.0°C/min. Binding of the drug slightly increased the denaturing temperature of the cleaned HSA due to a shift in the equilibrium toward the native protein bound with the drug. Diazepam depressed the denaturing temperature of the commercial HSA by competing with the stabilizers already bound to the primary site of the HSA. This yielded not only the HSA-stabilizer but also the HSA-diazepam type complexes that exhibited a different denaturation process. A rational approximation of the Lumry-Eyring protein denaturation model was used to treat the DSC endotherms. The approximated scheme: [Formula: see text] was successfully fitted to the data. It was used to determine the dissociation parameters for diazepam and ibuprofen bound to the HSA. These results were comparable to those obtained from other methods.

  8. Thermodynamics of calmodulin trapping by Ca2+/calmodulin-dependent protein kinase II: subpicomolar Kd determined using competition titration calorimetry.

    Science.gov (United States)

    Tse, Joyce K Y; Giannetti, Anthony M; Bradshaw, J Michael

    2007-04-03

    Calmodulin (CaM) trapping by Ca2+/calmodulin-dependent protein kinase II (CaMKII) is a phenomenon whereby the affinity of CaM for CaMKII increases >1000-fold following CaMKII autophosphorylation. The molecular basis of this effect is not entirely understood. Binding of CaM to the phosphorylated and the unphosphorylated states of CaMKII is well mimicked by the interaction of CaM with two different length peptides taken from the CaM-binding region of CaMKII, peptides we refer to as the long and intermediate peptides. To better understand the conformational change accompanying CaM trapping, we have used isothermal titration calorimetry (ITC) to compare the binding thermodynamics of CaM to these peptides as well as to a shorter CaMKII-based peptide. Calorimetric analysis revealed that the enthalpy, rather than the entropy, distinguished binding of these three peptides. Furthermore, the heat capacity change was found to be similar for the long and intermediate peptides but smaller in magnitude for the short peptide. Direct titration of CaM with peptide provided the Kd value for the short peptide (Kd = 5.9 +/- 2.4 microM), but a novel, two-phased competitive binding strategy was necessary to ascertain the affinities of the intermediate (Kd = 0.17 +/- 0.06 nM) and long (Kd = 0.07 +/- 0.04 pM) peptides. To our knowledge, the Kd for the long peptide is the most potent measured to date using ITC. Together, the findings reported here support a model whereby the final conformational change accompanying CaM trapping buries little additional surface area but does involve formation of new hydrogen bonds and van der Waals contacts that contribute to formation of the high-affinity, CaM-trapped state.

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

    Science.gov (United States)

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

    2017-02-01

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

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

    Science.gov (United States)

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

    2015-02-01

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

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

    Science.gov (United States)

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

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

    Science.gov (United States)

    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...

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

    Science.gov (United States)

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

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

    Science.gov (United States)

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

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

    Science.gov (United States)

    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...

  16. Exploring variation in binding of Protein A and Protein G to immunoglobulin type G by isothermal titration calorimetry

    DEFF Research Database (Denmark)

    Lund, L. N.; Christensen, T.; Toone, E.

    2011-01-01

    calorimetry. The results indicate that both protein ligands bind IgG and Fc fragments strongly with Ka values in the range of 10(7)-10(8) M(-1) and for both ligands, the interaction with both IgG isotypes is enthalpically driven though entropically unfavorable. Moreover, variation in the standard entropic...

  17. Fluence correction factors for graphite calorimetry in a low-energy clinical proton beam: I. Analytical and Monte Carlo simulations

    DEFF Research Database (Denmark)

    Palmans, Hugo; Al-Sulaiti, L; Andreo, P

    2013-01-01

    -eq with a relative standard uncertainty of 0.3%. These results are of direct relevance to graphite calorimetry in low-energy protons but given that the fluence correction factor is almost solely influenced by non-elastic nuclear interactions the results are also relevant for plastic phantoms that consist of carbon...

  18. Structure-property relations in crystalline L-leucine obtained from calorimetry, X-rays, neutron and Raman scattering

    DEFF Research Database (Denmark)

    Facanha Filho, Pedro F.; Jiao, Xueshe; Freire, Paulo T. C.;

    2011-01-01

    We have studied the amino acid L-leucine (LEU) using inelastic neutron scattering, X-rays and neutron diffraction, calorimetry and Raman scattering as a function of temperature, focusing on the relationship between the local dynamics of the NH(3), CH(3), CH(2) and CO(2) moieties and the molecular...

  19. The Thermal Stability and Domain Interactions of the Mannitol Permease of Escherichia coli. A Differential Scanning Calorimetry Study

    NARCIS (Netherlands)

    Meijberg, Wim; Schuurman-Wolters, Gea K.; Scheek, Ruud M.; Robillard, George T.

    1998-01-01

    The thermal stability and domain interactions in the mannitol transporter from Escherichia coli, enzyme IImtl, have been studied by differential scanning calorimetry. To this end, the wild type enzyme, IICBAmtl, as well as IICBmtl and IICmtl, were reconstituted into a dimyristoylphosphatidylcholine

  20. The thermal stability and domain interactions of the mannitol permease of Escherichia coli - A differential scanning calorimetry study

    NARCIS (Netherlands)

    Meijberg, W.; Schuurman-Wolters, G.K.; Scheek, R.M.; Robillard, G.T.

    1998-01-01

    The thermal stability and domain interactions in the mannitol transporter from Escherichia coli, enzyme IImtl, have been studied by differential scanning calorimetry. To this end, the wild type enzyme, IICBAmtl, as well as IICBmtl and IICmtl, were reconstituted into a dimyristoylphosphatidylcholine

  1. Interaction between dry starch and plasticisers glycerol or ethylene glycol, measured by differential scanning calorimetry and solid state NMR spectroscopy

    NARCIS (Netherlands)

    Smits, A.L.M.; Kruiskamp, P.H.; Soest, van J.J.G.; Vliegenthart, J.F.G.

    2003-01-01

    The interaction of crystalline amylose and of crystalline and amorphous amylopectin with the plasticisers glycerol or ethylene glycol in the absence of water was studied, by using differential scanning calorimetry (DSC) and solid state nuclear magnetic resonance (NMR) spectroscopy. Upon heating

  2. Differential scanning calorimetry of poly(2,6 dimethyl-1,4 phenylene-oxide)-toluene solutions

    NARCIS (Netherlands)

    van Emmerik, P.T.; Smolders, C.A.

    1973-01-01

    A study has been made by differential scanning calorimetry of the phase separation phenomena of solutions of poly(2,6 dimethyl-1,4 phenylene-oxide) (PPO) in toluene. Upon cooling a homogeneous solution, liquid-liquid phase separation always precedes crystallization effects. By assuming the

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

    Science.gov (United States)

    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...

  4. Ring-shaped Calorimetry Information for a Neural eGamma Identification with ATLAS Detector

    CERN Document Server

    Da Fonseca Pinto, Joao Victor; The ATLAS collaboration; Oliveira Damazio, Denis; Seixas, Jose

    2016-01-01

    \\title{Ring-shaped Calorimetry Information for a Neural e/$\\gamma$ Identification with ATLAS Detector} After the successful operation of the Large Hadron Collider resulting with the discovery of the Higgs boson, a new data-taking period (Run 2) has started. For the first time, collisions are produced with energies of 13 TeV in the centre of mass. It is foreseen the luminosity increase, reaching values as high as $10^{34}cm^{-2}s^{-1}$ yet in 2015. These changes in experimental conditions bring a proper environment for possible new physics key-findings. ATLAS is the largest LHC detector and was designed for general-purpose physics studies. Many potential physics channels have electrons or photons in their final states. For efficient studies on these channels precise measurement and identification of such particles is necessary. The identification task consists of disentangling those particles (signal) from collimated hadronic jets (background). Reported work concerns the identification process based on the cal...

  5. Morphological Investigation into Starch Bio-Nanocomposites via Synchrotron Radiation and Differential Scanning Calorimetry

    Directory of Open Access Journals (Sweden)

    Huihua Liu

    2011-01-01

    Full Text Available We studied a hydrophilic, plasticized bionanocomposite system involving sorbitol plasticizer, amylose biopolymer, and montmorillonite (MMT for the presence of competitive interactions among them at different moisture content. Synchrotron analysis via small angle X-ray scattering (SAXS and thermal analysis using differential scanning calorimetry (DSC were performed to understand crystalline growth and the distribution of crystalline domains within the samples. The SAXS diffraction patterns showed reduced interhelix spacing in the amylose network indicating strong amylose-sorbitol interactions. Depending on the sorbitol and MMT concentration, these interactions also affected the free moisture content and crystalline domains. Domains of around 95 Å and 312 Å were found in the low-moisture-content samples as compared to a single domain of 95 Å in the high-moisture-content samples. DSC measurements confirmed that the MMT increased the onset and the melting temperature of nanocomposites. Moreover, the results showed that the ternary interactions among sorbitol-amylose-MMT supported the crystalline heterogeneity through secondary nucleation.

  6. Comparative study of isomalt and sucrose by means of continuous indirect calorimetry.

    Science.gov (United States)

    Thiébaud, D; Jacot, E; Schmitz, H; Spengler, M; Felber, J P

    1984-09-01

    Isomalt (Palatinit) an equimolar mixture of alpha-D-glucopyranosido-1,6-sorbitol and alpha-D-glucopyranosido-1,6-mannitol, was compared to sucrose in a prospective double-blind controlled crossover study. The acute effects of oral ingestion of 30-g loads of isomalt or sucrose on plasma glucose, insulin, free fatty acids (FFA), lactic acid, and carbohydrate (CHO) and lipid oxidation were studied over six hours by means of continuous indirect calorimetry in ten healthy normal-weight subjects. Unlike sucrose, whose ingestion was followed by significant changes in plasma glucose, insulin, and lactic acid during the first 60 minutes of the test, no significant changes in these parameters were observed following the administration of isomalt. The increase in CHO oxidation occurring between 30 and 150 minutes was significantly lower (P less than 0.01) following isomalt than after sucrose. Conversely, the decrease in lipid oxidation was significantly less (P less than 0.01) after isomalt in comparison to sucrose. It is concluded that the rise in CHO oxidation and in plasma glucose and insulin levels is markedly reduced when sucrose is replaced by an equal weight of isomalt. In contrast to other sugar substitutes, no increase in plasma lactic acid was observed after isomalt administration.

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

    Science.gov (United States)

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

    2016-05-31

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

  8. Pressure perturbation calorimetry, heat capacity and the role of water in protein stability and interactions.

    Science.gov (United States)

    Cooper, A; Cameron, D; Jakus, J; Pettigrew, G W

    2007-12-01

    It is widely acknowledged, and usually self-evident, that solvent water plays a crucial role in the overall thermodynamics of protein stabilization and biomolecular interactions. Yet we lack experimental techniques that can probe unambiguously the nature of protein-water or ligand-water interactions and how they might change during protein folding or ligand binding. PPC (pressure perturbation calorimetry) is a relatively new technique based on detection of the heat effects arising from application of relatively small pressure perturbations (+/-5 atm; 1 atm=101.325 kPa) to dilute aqueous solutions of proteins or other biomolecules. We show here how this can be related to changes in solvation/hydration during protein-protein and protein-ligand interactions. Measurements of 'anomalous' heat capacity effects in a wide variety of biomolecular interactions can also be related to solvation effects as part of a quite fundamental principle that is emerging, showing how the apparently unusual thermodynamics of interactions in water can be rationalized as an inevitable consequence of processes involving the co-operative interaction of multiple weak interactions. This leads to a generic picture of the thermodynamics of protein folding stabilization in which hydrogen-bonding plays a much more prominent role than has been hitherto supposed.

  9. Differential scanning calorimetry as a tool for protein folding and stability.

    Science.gov (United States)

    Johnson, Christopher M

    2013-03-01

    Differential scanning calorimetry measures the heat capacity of states and the excess heat associated with transitions that can be induced by temperature change. The integral of the excess heat capacity is the enthalpy for this process. Despite this potentially intimidating sounding physical chemistry background, DSC has found almost universal application in studying biological macromolecules. In the case of proteins, DSC can be used to determine equilibrium thermodynamic stability and folding mechanism but can also be used in a more qualitative manner screening for thermal stability as an indicator for, ligand binding, pharmaceutical formulation or conditions conducive to crystal growth. DSC usually forms part of a wider biophysical characterisation of the biological system of interest and so the literature is diverse and difficult to categorise for the technique in isolation. This review therefore describes the potential uses of DSC in studying protein folding and stability, giving brief examples of applications from the recent literature. There have also been some interesting developments in the use of DSC to determine barrier heights for fast folding proteins and in studying complex protein mixtures such as human plasma that are considered in more detail.

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

    Science.gov (United States)

    Krainer, Georg; Keller, Sandro

    2015-04-01

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

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

    Science.gov (United States)

    Callies, O; Hernández Daranas, A

    2016-07-28

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

  12. Application of isothermal titration calorimetry and column chromatography for identification of biomolecular targets.

    Science.gov (United States)

    Zhou, Xingding; Kini, R Manjunatha; Sivaraman, J

    2011-02-01

    This protocol describes a method for identifying unknown target proteins from a mixture of biomolecules for a given drug or a lead compound. This method is based on a combination of chromatography and isothermal titration calorimetry (ITC) where ITC is used as a tracking tool. The first step involves the use of ITC to confirm the binding of ligand to a component in the biomolecular mixture. Subsequently, the biomolecular mixture is fractionated by chromatography, and the binding of the ligand with individual fractions (or subfractions) is verified by ITC. The iteration of chromatographic purification on the fractions combined with ITC results in identifying the target protein. This method is useful when the target protein or ligand is unknown and/or not amenable to labeling, chemical modification or immobilization. This protocol has been successfully used by our team and by others to identify both low-abundance and highly abundant target proteins present in biomolecular mixtures. With this protocol, it takes approximately 3-5 d to identify the target protein from a mixture.

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

    Science.gov (United States)

    Lonhienne, T; Baise, E; Feller, G; Bouriotis, V; Gerday, C

    2001-02-09

    Isothermal titration calorimetry has been applied to the determination of the kinetic parameters of chitinases (EC 3.2.1.14) by monitoring the heat released during the hydrolysis of chitin glycosidic bonds. Experiments were carried out using two different macromolecular substrates: a soluble polymer of N-acetylglucosamine and the insoluble chitin from crab shells. Different experimental temperatures were used in order to compare the thermodependence of the activity of two chitinases from the psychrophile Arthrobacter sp. TAD20 and of chitinase A from the mesophile Serratia marcescens. The method allowed to determine unequivocally the catalytic rate constant k(cat), the activation energy (E(a)) and the thermodynamic activation parameters (DeltaG(#), DeltaH(#), DeltaS(#)) of the chitinolytic reaction on the soluble substrate. The catalytic activity has also been determined on insoluble chitin, which displays an effect of substrate saturation by chitinases. On both substrates, the thermodependence of the activity of the psychrophilic chitinases was lower than that observed with the mesophilic counterpart.

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

    Science.gov (United States)

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

    2016-05-25

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

  15. Assessment of glucose metabolism in humans with the simultaneous use of indirect calorimetry and tracer techniques.

    Science.gov (United States)

    Tappy, L; Paquot, N; Tounian, P; Schneiter, P; Jéquier, E

    1995-01-01

    Concomitant measurements of sytemic glucose delivery and carbohydrate oxidation are frequently performed in human investigations. Systemic glucose delivery (SGD) is usually determined using dilution of infused glucose tracers; net carbohydrate oxidation rate (net CHOOX) can be calculated from respiratory gas exchanges and urinary nitrogen excretion (indirect calorimetry); alternatively, glucose oxidation can be measured from labelled CO2 production during infusion of carbon-labelled glucose tracers. In this paper, the theory underlying the use of each of these techniques is briefly reviewed and qualitative differences are outlined. SGD represents the sum of hepatic glucogenolysis, gluconeogenesis from amino acids or glycerol, and, according to the glucose tracer used, glucose cycles (glucose-phosphate cycle, fructose-phosphate cycle, Cori and glucose-alanine cycles); systemic delivery of exogenous glucose after oral or i.v. glucose administration is also measured. Net CHOOX represents oxidation of glucose arising from hepatic or muscle glycogen or from exogenous glucose; it does not take into account oxidation of glucose formed from amino acids or glycerol, which is included in net protein or lipid oxidation. In contrast, isotopic determination of glucose oxidation corresponds to oxidation of glucose originating from hepatic glycogen breakdown, of exogenously administered glucose, and of glucose formed from amino acids and glycerol. Non-oxidative glucose disposal, calculated as SGD-net CHOOX, corresponds to the sum of gluconeogenesis from amino acids or glycerol (which are included in net protein and lipid oxidation), glucose cycles, and glycogen synthesis.

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

    Science.gov (United States)

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

    2011-06-30

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

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

    Science.gov (United States)

    2013-01-01

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

  18. Lipoprotein lipase activity and interactions studied in human plasma by isothermal titration calorimetry.

    Science.gov (United States)

    Reimund, Mart; Kovrov, Oleg; Olivecrona, Gunilla; Lookene, Aivar

    2017-01-01

    LPL hydrolyzes triglycerides in plasma lipoproteins. Due to the complex regulation mechanism, it has been difficult to mimic the physiological conditions under which LPL acts in vitro. We demonstrate that isothermal titration calorimetry (ITC), using human plasma as substrate, overcomes several limitations of previously used techniques. The high sensitivity of ITC allows continuous recording of the heat released during hydrolysis. Both initial rates and kinetics for complete hydrolysis of plasma lipids can be studied. The heat rate was shown to correspond to the release of fatty acids and was linearly related to the amount of added enzyme, either purified LPL or postheparin plasma. Addition of apoC-III reduced the initial rate of hydrolysis by LPL, but the inhibition became less prominent with time when the lipoproteins were triglyceride poor. Addition of angiopoietin-like protein (ANGPTL)3 or ANGPTL4 caused reduction of the activity of LPL via a two-step mechanism. We conclude that ITC can be used for quantitative measurements of LPL activity and interactions under in vivo-like conditions, for comparisons of the properties of plasma samples from patients and control subjects as substrates for LPL, as well as for testing of drug candidates developed with the aim to affect the LPL system. Copyright © 2017 by the American Society for Biochemistry and Molecular Biology, Inc.

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

    Science.gov (United States)

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

    2017-04-01

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

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

    Science.gov (United States)

    Li, Xiangrong; Yang, Zhenhua

    2015-05-05

    Oridonin has been traditionally and widely used for treatment of various human diseases due to its uniquely biological, pharmacological and physiological functions. In this study, the interaction between oridonin and human serum albumin (HSA) was investigated using isothermal titration calorimetry (ITC), in combination with fluorescence spectroscopy and UV-vis absorption spectroscopy. We found that the hydrogen bond and van der Waals force are the major binding forces in the binding of oridonin to HSA. The binding of oridonin to HSA is driven by favorable enthalpy and unfavorable entropy. Oridonin can quench the fluorescence of HSA through a static quenching mechanism. The binding constant between oridonin and HSA is moderate and the equilibrium fraction of unbound oridonin f(u) > 60%. Binding site I is found to be the primary binding site for oridonin. Additionally, oridonin may induce conformational changes of HSA and affect its biological function as the carrier protein. The results of the current study suggest that oridonin can be stored and transported from the circulatory system to reach its target organ to provide its therapeutic effects. But its side-effect in the clinics cannot be overlook. The study provides an accurate and full basic data for clarifying the binding mechanism of oridonin with HSA and is helpful for understanding its effect on protein function during the blood transportation process and its biological activity in vivo. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  1. Kinetics of trypsin-catalyzed hydrolysis determined by isothermal titration calorimetry.

    Science.gov (United States)

    Maximova, Ksenia; Trylska, Joanna

    2015-10-01

    Isothermal titration calorimetry (ITC) was applied to determine enzymatic activity and inhibition. We measured the Michaelis-Menten kinetics for trypsin-catalyzed hydrolysis of two substrates, casein (an insoluble macromolecule substrate) and Nα-benzoyl-dl-arginine β-naphthylamide (a small substrate), and estimated the thermodynamic parameters in the temperature range from 20 to 37°C. The inhibitory activities of reversible (small molecule benzamidine) and irreversible (small molecule phenylmethanesulfonyl fluoride and macromolecule α1-antitrypsin) inhibitors of trypsin were also determined. We showed the usefulness of ITC for fast and direct measurement of inhibition constants and half-maximal inhibitory concentrations and for predictions of the mechanism of inhibition. ITC kinetic assays could be an easy and straightforward way to estimate Michaelis-Menten constants and the effectiveness of inhibitors as well as to predict the inhibition mechanism. ITC efficiency was found to be similar to that of classical spectrophotometric enzymatic assays. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Microtubule-associated proteins and tubulin interaction by isothermal titration calorimetry.

    Science.gov (United States)

    Tsvetkov, P O; Barbier, P; Breuzard, G; Peyrot, V; Devred, F

    2013-01-01

    Microtubules play an important role in a number of vital cell processes such as cell division, intracellular transport, and cell architecture. The highly dynamic structure of microtubules is tightly regulated by a number of stabilizing and destabilizing microtubule-associated proteins (MAPs), such as tau and stathmin. Because of their importance, tubulin-MAPs interactions have been extensively studied using various methods that provide researchers with complementary but sometimes contradictory thermodynamic data. Isothermal titration calorimetry (ITC) is the only direct thermodynamic method that enables a full thermodynamic characterization (stoichiometry, enthalpy, entropy of binding, and association constant) of the interaction after a single titration experiment. This method has been recently applied to study tubulin-MAPs interactions in order to bring new insights into molecular mechanisms of tubulin regulation. In this chapter, we review the technical specificity of this method and then focus on the use of ITC in the investigation of tubulin-MAPs binding. We describe technical issues which could arise during planning and carrying out the ITC experiments, in particular with fragile proteins such as tubulin. Using examples of stathmin and tau, we demonstrate how ITC can be used to gain major insights into tubulin-MAP interaction. Copyright © 2013 Elsevier Inc. All rights reserved.

  3. Biomolecule-nanoparticle interactions: Elucidation of the thermodynamics by isothermal titration calorimetry.

    Science.gov (United States)

    Huang, Rixiang; Lau, Boris L T

    2016-05-01

    Nanomaterials (NMs) are often exposed to a broad range of biomolecules of different abundances. Biomolecule sorption driven by various interfacial forces determines the surface structure and composition of NMs, subsequently governs their functionality and the reactivity of the adsorbed biomolecules. Isothermal titration calorimetry (ITC) is a nondestructive technique that quantifies thermodynamic parameters through in-situ measurement of the heat absorption or release associated with an interaction. This review highlights the recent applications of ITC in understanding the thermodynamics of interactions between various nanoparticles (NPs) and biomolecules. Different aspects of a typical ITC experiment that are crucial for obtaining accurate and meaningful data, as well as the strengths, weaknesses, and challenges of ITC applications to NP research were discussed. ITC reveals the driving forces behind biomolecule-NP interactions and the effects of the physicochemical properties of both NPs and biomolecules by quantifying the crucial thermodynamics parameters (e.g., binding stoichiometry, ΔH, ΔS, and ΔG). Complimentary techniques would strengthen the interpretation of ITC results for a more holistic understanding of biomolecule-NP interactions. The thermodynamic information revealed by ITC and its complimentary characterizations is important for understanding biomolecule-NP interactions that are fundamental to the biomedical and environmental applications of NMs and their toxicological effects. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Appropriateness of the definition of 'sedentary' in young children: Whole-room calorimetry study.

    Science.gov (United States)

    Reilly, John J; Janssen, Xanne; Cliff, Dylan P; Okely, Anthony D

    2015-09-01

    The present study aimed to measure the energy cost of three common sedentary activities in young children to test whether energy expended was consistent with the recent consensus definition of 'sedentary' as 'any behaviour conducted in a sitting or reclining posture and with an energy cost ≤ 1.5 metabolic equivalents (METs)' (Sedentary Behaviour Research Network, 2012). Observational study. Whole-room calorimetry measures of television viewing, sitting at a table drawing and reading, and sitting on the floor playing with toys were made in 40 young children (mean age 5.3 years, SD 1.0). The energy cost of each sedentary activity was consistent with the recent consensus definition of sedentary: 1.17 METs (95% CI 1.07-1.27) for TV viewing; 1.38 METs (95% CI 1.30-1.46) for sitting at a table; and 1.35 METs (95% CI 1.28-1.43) for floor-based play. Common sedentary activities in young children have energy costs which are consistent with the recent consensus definition of 'sedentary', and the present study is supportive of this definition. Copyright © 2014 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

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

    2016-03-10

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

  6. Changes in polymer foils used in food packaging tested by using differential scanning calorimetry

    Indian Academy of Sciences (India)

    J Gajdoš Kljusurić

    2003-12-01

    This work is an experimental study of the differential scanning calorimetry characterisation of polymer materials used in food packaging materials, such as polypropylene (0.03 mm), polyethylene (0.1 and 0.03 mm), poly(D-(-)--hydroxybutyrate) (powder), two-layered polypropylene (0.064 mm), and two-layered polypropylene with poly-vinylidene-chloride (0.012/0.021). The polymer stability was checked by simulation of conditions during food preparation in microwave ovens, sterilisation or rapid freezing. The materials were tested in the temperature range from 40 to 200°C at different scan rates from 2 to 30° C min-1 during heating or cooling. The enthalpies show a high correlation coefficient (0.964) with scan rate. All samples undergo phase change in the temperature range from 107 to 173°C during heating and enthalpies are in the range from 31.8 to 71.1 J g−1 Upon subsequent cooling from 200°C, the temperature range of phase changes is shifted to lower temperatures from 86 to 102°C with enthalpies ranging from 30.4 to 57.8 J g−1. Experiments with exposure of polymers to microwave radiation and freezing prove that the phase change considering the temperature range is very similar in all experiments.

  7. Single-crystal adsorption calorimetry and density functional theory of CO chemisorption on fcc Co{110}.

    Science.gov (United States)

    Liao, Kristine; Fiorin, Vittorio; Gunn, David S D; Jenkins, Stephen J; King, David A

    2013-03-21

    Using single-crystal adsorption calorimetry (SCAC) and density functional theory (DFT), the interaction of carbon monoxide on fcc Co{110} is reported for the first time. The results indicate that adsorption is consistent with molecular chemisorption at all coverages. The initial heat of adsorption of 140 kJ mol(-1) is found in the range of heat values calorimetrically measured on other ferromagnetic metal surfaces, such as nickel and iron. DFT adsorption energies are in good agreement with the experimental results, and comparison between SCAC and DFT for CO on other ferromagnetic surfaces is made. The calculated dissociation barrier of 2.03 eV implies that dissociation at 300 K is unlikely even at the lowest coverage. At high coverages during the adsorption-desorption steady state regime, a pre-exponential factor for CO desorption of 1.2 × 10(17) s(-1) is found, implying a localised molecular adsorbed state prior to desorption in contrast to what we found with Ni surfaces. This result highlights the importance of the choice of the pre-exponential factor in evaluating the activation energy for desorption.

  8. Applications of differential scanning calorimetry for thermal stability analysis of proteins: qualification of DSC.

    Science.gov (United States)

    Wen, Jie; Arthur, Kelly; Chemmalil, Letha; Muzammil, Salman; Gabrielson, John; Jiang, Yijia

    2012-03-01

    Differential scanning calorimetry (DSC) has been used to characterize protein thermal stability, overall conformation, and domain folding integrity by the biopharmaceutical industry. Recently, there have been increased requests from regulatory agencies for the qualification of characterization methods including DSC. Understanding the method precision can help determine what differences between samples are significant and also establish the acceptance criteria for comparability and other characterization studies. In this study, we identify the parameters for the qualification of DSC for thermal stability analysis of proteins. We use these parameters to assess the precision and sensitivity of DSC and demonstrate that DSC is suitable for protein thermal stability analysis for these purposes. Several molecules from different structural families were studied. The experiments and data analyses were performed by different analysts using different instruments at different sites. The results show that the (apparent) thermal transition midpoint (T(m)) values obtained for the same protein by same and different instruments and/or analysts are quite reproducible, and the profile similarity values obtained for the same protein from the same instrument are also high. DSC is an appropriate method for assessing protein thermal stability and conformational changes.

  9. Characterizing Plexin GTPase Interactions Using Gel Filtration, Surface Plasmon Resonance Spectrometry, and Isothermal Titration Calorimetry.

    Science.gov (United States)

    Muller-Greven, Jeannine; Kim, SoonJeung; Hota, Prasanta K; Tong, Yufeng; Borthakur, Susmita; Buck, Matthias

    2017-01-01

    Plexins are unique, as they are the first example of a transmembrane receptor that interacts directly with small GTPases, a family of proteins that are essential for cell motility and proliferation/survival. We and other laboratories have determined the structure of the Rho GTPase-binding domain (RBD) of several plexins and also of the entire intracellular region of plexin-B1. Structures of plexin complexes with Rho GTPases, Rac1 and Rnd1, and a structure with a Ras GTPase, Rap1b, have also been solved. The relationship between plexin-Rho and plexin-Ras interactions is still unclear and in vitro biophysical experiments that characterize the protein interactions of purified components play an important role in advancing our understanding of the molecular mechanisms that underlie the function of plexin. This chapter describes the use of gel filtration (also known as size-exclusion chromatography or SEC), surface plasmon resonance (SPR), and isothermal titration calorimetry (ITC) in studies of plexin-small GTPase interactions with plexin-B1:Rac1 as an example. Together with other assays and manipulations (e.g., by mutagenesis or protein domain truncation/deletion), these in vitro measurements provide an important reference for the role and extent of the interactions.

  10. Thermodynamics of the complexation of Hg(II) by cysteinyl peptide ligands using isothermal titration calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Ngu-Schwemlein, Maria, E-mail: Schwemleinmn@wssu.edu [Department of Chemistry, Winston-Salem State University, Winston-Salem, NC 27110 (United States); Merle, John K.; Healy, Patrick; Schwemlein, Stefanie; Rhodes, Sade [Department of Chemistry, Winston-Salem State University, Winston-Salem, NC 27110 (United States)

    2009-12-10

    The present study was undertaken to better understand the complexation of mercury (II) by cysteine, histidine, tryptophan, and their di- and tri-peptides. Their mercury (II) binding affinities and associated thermodynamic parameters are evaluated by isothermal titration calorimetry. Cysteine S-donor atoms form the strongest complexes, which can be attributed to a more exothermic Hg-S soft acid and soft base interaction. These thiol S-donor peptide ligands show two sequential binding for mercury (II). Their stability constants for the first binding (10{sup 8} M{sup -1} to >10{sup 10} M{sup -1}) are largely due to favorable contribution of the enthalpy term to the free energy of complexation. As more mercury (II) ions are added, this enthalpy contribution decreases and the free energy of the second binding (10{sup 5} M{sup -1} to 10{sup 6} M{sup -1}) is partially compensated by the entropy term. The dependency of the fluorescence intensity for these peptides on mercury (II) concentration shows two different Stern-Volmer plots, which corroborates the calorimetric data and supports the formation of two types of stable complexes.

  11. Microscopy and calorimetry as complementary techniques to analyze sugar crystallization from amorphous systems.

    Science.gov (United States)

    Mazzobre, María F; Aguilera, José M; Buera, María P

    2003-03-14

    A comparison of microscopic and macroscopic techniques to evaluate sugar crystallization kinetics is presented using amorphous lactose and lactose-trehalose mixtures. Polarized light video microscopy (PLV) and differential scanning calorimetry (DSC) were applied to measure crystallization kinetics, induction times and time for complete sugar crystallization at different storage temperatures (60-95 degrees C). DSC was also employed to measure the glass transition temperature (T(ag)) of the systems. PLV permitted direct observation, in real time, of growth of individual crystals and morphological aspects at a scale not detected by DSC. Taking the average of several microscopic observations, the results for temperature dependence of crystallization rate and time to complete lactose crystallization were similar to those obtained by DSC. Both PLV and DSC techniques showed that the presence of trehalose delayed lactose crystallization, without affecting the T(ag) value. For the analysis of sugar crystallization in amorphous systems, PLV and DSC proved to be complementary techniques. Validation of results obtained by PLV with results from DSC opens a new area of microstructural analysis of crystallizing systems.

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

    Science.gov (United States)

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

    2015-09-01

    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—{Fe}3{O}4.The investigations were performed as a function of the nanoparticles' concentration. Small increases of thermal diffusivity (from 9.06× 10^{-8} {m}2{\\cdot } {s}^{-1} up to 9.84× 10^{-8} {m}2{\\cdot } {s}^{-1}) and thermal effusivity (from 450 {W}{\\cdot } {s}^{1/2}{\\cdot } {m}^{-2}{\\cdot } {K}^{-1} up to 520 {W}{\\cdot } {s}^{1/2}{\\cdot } {m}^{-2}{\\cdot } {K}^{-1}) with increasing concentration of {Fe}3{O}4 nanoparticles (from 0 up to 0.623 mg {Fe}3{O}4/{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.

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

    Science.gov (United States)

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

    2011-12-01

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

  14. A survey of the year 2007 literature on applications of isothermal titration calorimetry.

    Science.gov (United States)

    Bjelić, Sasa; Jelesarov, Ilian

    2008-01-01

    Elucidation of the energetic principles of binding affinity and specificity is a central task in many branches of current sciences: biology, medicine, pharmacology, chemistry, material sciences, etc. In biomedical research, integral approaches combining structural information with in-solution biophysical data have proved to be a powerful way toward understanding the physical basis of vital cellular phenomena. Isothermal titration calorimetry (ITC) is a valuable experimental tool facilitating quantification of the thermodynamic parameters that characterize recognition processes involving biomacromolecules. The method provides access to all relevant thermodynamic information by performing a few experiments. In particular, ITC experiments allow to by-pass tedious and (rarely precise) procedures aimed at determining the changes in enthalpy and entropy upon binding by van't Hoff analysis. Notwithstanding limitations, ITC has now the reputation of being the "gold standard" and ITC data are widely used to validate theoretical predictions of thermodynamic parameters, as well as to benchmark the results of novel binding assays. In this paper, we discuss several publications from 2007 reporting ITC results. The focus is on applications in biologically oriented fields. We do not intend a comprehensive coverage of all newly accumulated information. Rather, we emphasize work which has captured our attention with originality and far-reaching analysis, or else has provided ideas for expanding the potential of the method. Copyright (c) 2008 John Wiley & Sons, Ltd.

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

    Energy Technology Data Exchange (ETDEWEB)

    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); 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); Universite de Toulouse, UPS, IPBS, F-31077 Toulouse (France); Winterhalter, Mathias [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); 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); Universite de Toulouse, UPS, IPBS, F-31077 Toulouse (France)

    2009-07-31

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

  16. Forward calorimetry for heavy-ion physics at the STAR experiment

    Science.gov (United States)

    Brown, Daniel; STAR Experiment at RHIC Collaboration; STAR Forward Calorimeter Group Team

    2017-01-01

    A forward calorimeter utilizing hadronic and electromagnetic calorimetry at the STAR experiment of RHIC will achieve a variety of physics goals. These goals include studying long-range rapidity correlations, event plane correlations in heavy-ion interactions, and studying the gluon contribution to the proton spin. Upgrades to the AGS E864 lead-scintillating fiber calorimeter have increased spatial resolution by utilizing cell pixelization. Light collection has been optimized and fringe field effects have been minimized by the introduction of Fresnel lenses and mu-metal shielding. A prototype consisting of a 2x3 cell stack was installed into the forward region of STAR for the end of run16. This prototype investigated the introduction of these new techniques as well as a trial of Silicon Photomultipliers (SiPMs) as an alternate to traditional Photomultiplier Tubes (PMTs). SiPMs do not suffer from fringe field effects, but are susceptible to radiation damage by neutrons, so their performance during the prototype operation was analyzed. This talk will discuss the effects of Fresnel lenses on light collection, mu-metal shielding effects on PMTs, and radiation effects on SiPMs.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-10-01

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

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

    Science.gov (United States)

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

    2009-04-05

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

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

    Energy Technology Data Exchange (ETDEWEB)

    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

    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.

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

    Science.gov (United States)

    Migdał-Mikuli, Anna; Skoczylas, Łukasz

    2008-12-01

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

  1. Application of Differential Scanning Calorimetry (DSC in study of phase transformations in ductile iron

    Directory of Open Access Journals (Sweden)

    R. Przeliorz

    2010-04-01

    Full Text Available The effect of heating rate on phase transformations to austenite range in ductile iron of the EN-GJS-450-10 grade was investigated. For studies of phase transformations, the technique of differential scanning calorimetry (DSC was used. Microstructure was examined by optical microscopy. The calorimetric examinations have proved that on heating three transformations occur in this grade of ductile iron, viz. magnetic transformation at the Curie temperature, pearlite→austenite transformation and ferrite→austenite transformation. An increase in the heating rate shifts the pearlite→austenite and ferrite→austenite transformations to higher temperature range. At the heating rate of 5 and 15°C/min, local extrema have been observed to occur: for pearlite→austenite transformation at 784°C and 795°C, respectively, and for ferrite→austenite transformation at 805°C and 821°C, respectively. The Curie temperature of magnetic transformation was extrapolated to a value of 740°C. Each transformation is related with a specific thermal effect. The highest value of enthalpy is accompanying the ferrite→austenite transformation, the lowest occurs in the case of pearlite→austenite transformation.

  2. Phosphate sorption by three potential filter materials as assessed by isothermal titration calorimetry.

    Science.gov (United States)

    Lyngsie, Gry; Penn, Chad J; Hansen, Hans C B; Borggaard, Ole K

    2014-10-01

    Phosphorus eutrophication of lakes and streams, coming from drained farmlands, is a serious problem in areas with intensive agriculture. Installation of phosphate (P) sorbing filters at drain outlets may be a solution. The aim of this study was to improve the understanding of reactions involved in P sorption by three commercial P sorbing materials, i.e. Ca/Mg oxide-based Filtralite-P, Fe oxide-based CFH-12 and Limestone in two particle sizes (2-1 mm and 1-0.5 mm), by means of isothermal titration calorimetry (ITC), sorption isotherms, sequential extractions and SEM-EDS. The results indicate that P retention by CFH is due to surface complexation by rapid formation of strong Fe-P bonds. In contrast, retention of P by Filtralite-P and Limestone strongly depends on pH and time and is interpreted due to formation of calcium phosphate precipitate(s). Consequently, CFH can unambiguously be recommended as P retention filter material in drain outlets, whereas the use of Filtralite-P and Limestone has certain (serious) limitations. Thus, Filtralite-P has high capacity to retain P but only at alkaline pH (pH ≥ 10) and P retention by Limestone requires long-time contact and a high ratio between sorbent and sorbate.

  3. Thermodynamic Study of 8-Hydroxyquinoline by Adiabatic Calorimetry and Thermal Analysis

    Institute of Scientific and Technical Information of China (English)

    WANG Shao-Xu; TAN Zhi-Cheng; LI Yan-Sheng; TONG Bo; LI Ying; SHI Quan; ZHANG Jing-Nan

    2008-01-01

    A calorimetric study and thermal analysis for 8-hydroxyquinoline were performed.The low-temperature heat capacity of this compound was measured with a precise automated adiabatic calorimeter over the temperature range from 78 to 370 K.The melting point True,molar enthalpy △fusHm and molar entropy △fusSm of fusion of this sub-tively.The thermodynamic functions of the substance,such as molar enthalpy and entropy of fusion,and thermo-dynamic functions [Hr-H298.15] and [ST-S298.15] were derived from two polynomial equations of the experi-mental molar heat capacities against the reduced temperature fitted by the least square method.The melting tem-peratures for the sample and the absolutely pure compound have been obtained from fractional melting experiments to be 345.601 and 345.761 K,respectively,and the molar fraction purity of the sample was calculated to be 0.9978 according to the van't Hoff equation.The thermal stability of the compound was further investigated by differential scanning calorimetry(DSC).

  4. Mechanic Insight into Aggregation of Lysozyme by Ultrasensitive Differential Scanning Calorimetry and Sedimentation Velocity.

    Science.gov (United States)

    Wu, Sha; Ding, Yanwei; Zhang, Guangzhao

    2015-12-31

    Folding and aggregation of proteins profoundly influence their functions. We have investigated the effects of thermal history, concentration and pH on the denaturation and refolding of lysozyme by using ultrasensitive differential scanning calorimetry (US-DSC) and sedimentation velocity (SV) via analytical ultracentrifugation (AUC). The former is sensitive to small energy change whereas the latter can differentiate the oligomers such as dimer and trimer from individual protein molecules. Our studies reveal that the degree of denaturation irreversibility increases as heating times increases. The denaturation temperature (Td) and enthalpy change (ΔH) are influenced by heating rate since the denaturation is not in equilibrium during the heating. We can obtain Td and ΔH in equilibrium by extrapolation of heating rate to zero. In a dilute solution, no aggregation but unfolding happens in the denaturation. However, when the concentration is above a critical value (∼15.0 mg/mL), lysozyme molecules readily form trimers or other oligomers. Lysozyme molecules unfold into stretched chains at pH > 6.0, which would further forms large aggregates. The formation of aggregates makes the refolding of lysozyme impossible.

  5. Deconvolution analysis for classifying gastric adenocarcinoma patients based on differential scanning calorimetry serum thermograms.

    Science.gov (United States)

    Vega, Sonia; Garcia-Gonzalez, María Asuncion; Lanas, Angel; Velazquez-Campoy, Adrian; Abian, Olga

    2015-01-23

    Recently, differential scanning calorimetry (DSC) has been acknowledged as a novel tool for diagnosing and monitoring several diseases. This highly sensitive technique has been traditionally used to study thermally induced protein folding/unfolding transitions. In previous research papers, DSC profiles from blood samples of patients were analyzed and they exhibited marked differences in the thermal denaturation profile. Thus, we investigated the use of this novel technology in blood serum samples from 25 healthy subjects and 30 patients with gastric adenocarcinoma (GAC) at different stages of tumor development with a new multiparametric approach. The analysis of the calorimetric profiles of blood serum from GAC patients allowed us to discriminate three stages of cancer development (I to III) from those of healthy individuals. After a multiparametric analysis, a classification of blood serum DSC parameters from patients with GAC is proposed. Certain parameters exhibited significant differences (P < 0.05) and allowed the discrimination of healthy subjects/patients from patients at different tumor stages. The results of this work validate DSC as a novel technique for GAC patient classification and staging, and offer new graphical tools and value ranges for the acquired parameters in order to discriminate healthy from diseased subjects with increased disease burden.

  6. A new quantitative method to measure activity of ice structuring proteins using differential scanning calorimetry.

    Science.gov (United States)

    Hassa-Roudsari, Majid; Goff, H Douglas

    2012-01-01

    There are very few quantitative assays to measure the activity of antifreeze proteins (AFPs, or Ice Structuring Proteins, ISPs) and these can be prone to various inaccuracies and inconsistencies. Some methods rely only on unassisted visual assessment. When microscopy is used to measure ice crystal size, it is critical that standardized procedures be adopted, especially when image analysis software is used to quantify sizes. Differential Scanning Calorimetry (DSC) has been used to measure the thermal hysteresis activity (TH) of AFPs. In this study, DSC was used isothermally to measure enthalpic changes associated with structural rearrangements as a function of time. Differences in slopes of isothermal heat flow vs. time between winter wheat ISP or AFP type I containing samples, and those without ISP or AFP type I were demonstrated. ISP or AFP type I containing samples had significantly higher slopes compared to those without ISP or AFP type I. Samples with higher concentration of ISP or AFP type I showed higher slope values during the first hour and took up to 3 hr to attain equilibrium. Differences were attributed to activity of the proteins at the ice interface. Proteinaceous activity of ISPs or AFP type I was confirmed by loss of activity after treatment with protease.

  7. Differential Scanning Calorimetry — A Method for Assessing the Thermal Stability and Conformation of Protein Antigen

    Science.gov (United States)

    Durowoju, Ibrahim B.; Bhandal, Kamaljit S.; Hu, Jian; Carpick, Bruce; Kirkitadze, Marina

    2017-01-01

    Differential scanning calorimetry (DSC) is an analytical technique that measures the molar heat capacity of samples as a function of temperature. In the case of protein samples, DSC profiles provide information about thermal stability, and to some extent serves as a structural “fingerprint” that can be used to assess structural conformation. It is performed using a differential scanning calorimeter that measures the thermal transition temperature (melting temperature; Tm) and the energy required to disrupt the interactions stabilizing the tertiary structure (enthalpy; ∆H) of proteins. Comparisons are made between formulations as well as production lots, and differences in derived values indicate differences in thermal stability and structural conformation. Data illustrating the use of DSC in an industrial setting for stability studies as well as monitoring key manufacturing steps are provided as proof of the effectiveness of this protocol. In comparison to other methods for assessing the thermal stability of protein conformations, DSC is cost-effective, requires few sample preparation steps, and also provides a complete thermodynamic profile of the protein unfolding process. PMID:28287565

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

    Science.gov (United States)

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

    2016-03-01

    The thermal oxidation of eight different vegetable oils was studied using differential scanning calorimetry (DSC) under non-isothermal conditions at five different heating rates (5, 7.5, 10, 12.5, and 15°C/min), in a temperature range of 100-400°C. For all oils, the activation energy (Ea) values at Tp were smaller than that at Ts and Ton. Among all the oils, refined palm oil (RPO) exhibited the highest Ea values, 126.06kJ/mol at Ts, 134.7kJ/mol at Ton, and 91.88kJ/mol at Tp. The Ea and reaction rate constant (k) values at Ts, Ton, and Tp were further correlated with oil compositions (fatty acids and triacylglycerols) using Pearson correlation analysis. The rate constant (k) and Ea of all oils exhibited varying correlations with FAs and TAGs, indicating that the thermal oxidation behaviors were affected by oil compositions. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Heat resistance of viable but non-culturable Escherichia coli cells determined by differential scanning calorimetry.

    Science.gov (United States)

    Castro-Rosas, Javier; Gómez-Aldapa, Carlos Alberto; Villagómez Ibarra, José Roberto; Santos-López, Eva María; Rangel-Vargas, Esmeralda

    2017-10-16

    Several reports have suggested that the viable but non-culturable (VBNC) state is a resistant form of bacterial cells that allows them to remain in a dormant form in the environment. Nevertheless, studies on the resistance of VBNC bacterial cells to ecological factors are limited, mainly because techniques that allow this type of evaluation are lacking. Differential scanning calorimetry (DSC) has been used to study the thermal resistance of culturable bacteria but has never been used to study VBNC cells. In this work, the heat resistance of Escherichia coli cells in the VBNC state was studied using the DSC technique. The VBNC state was induced in E. coli ATCC 25922 by suspending bacterial cells in artificial sea water, followed by storage at 3 ± 2°C for 110 days. Periodically, the behaviour of E. coli cells was monitored by plate counts, direct viable counts and DSC. The entire bacterial population entered the VBNC state after 110 days of storage. The results obtained with DSC suggest that the VBNC state does not confer thermal resistance to E. coli cells in the temperature range analysed here. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  10. Evaluation of the thermal property of bovine intramuscular adipose tissue using differential scanning calorimetry.

    Science.gov (United States)

    Kimura, Noriyuki; Nishimura, Nana; Iwama, Nagako; Aihara, Yoshito; Ogawa, Yasuki; Miyaguchi, Yuji

    2017-10-01

    The thermal property of bovine intramuscular adipose tissue (IAT) was evaluated using differential scanning calorimetry (DSC) and compared with the melting point temperature (MP) of the fat extract of IAT, which was measured using the slip point method. The beef samples were classified according to the beef marbling score (BMS). Beef with a high BMS contained less protein than that with middle or low BMS. Beef with a high BMS contained significantly more fat than that with a low BMS (P < 0.05). The endothermic point temperature (EP) of IAT, measured by DSC, was significantly higher than the MP of IAT fat (P < 0.05). The EP showed no significant difference among the three marbling grade groups. Although the MP was correlated with the monounsaturated fatty acids (MUFA) content of IAT (R(2)  = 0.505), there was no correlation between the EP and the MUFA (R(2)  = 0.040). However, the EP of IAT treated with collagenase was relatively highly correlated with the MP (R(2)  = 0.655). Thus, these results suggested that DSC analysis would give us the practical thermal information regarding the melt-in the-mouth of beef such as the gelatinization of collagen, along with the melting of fat in IAT. © 2017 The Authors. Animal Science Journal published by John Wiley & Sons Australia, Ltd on behalf of Japanese Society of Animal Science.

  11. Differential Scanning Calorimetry - A Method for Assessing the Thermal Stability and Conformation of Protein Antigen.

    Science.gov (United States)

    Durowoju, Ibrahim B; Bhandal, Kamaljit S; Hu, Jian; Carpick, Bruce; Kirkitadze, Marina

    2017-03-04

    Differential scanning calorimetry (DSC) is an analytical technique that measures the molar heat capacity of samples as a function of temperature. In the case of protein samples, DSC profiles provide information about thermal stability, and to some extent serves as a structural "fingerprint" that can be used to assess structural conformation. It is performed using a differential scanning calorimeter that measures the thermal transition temperature (melting temperature; Tm) and the energy required to disrupt the interactions stabilizing the tertiary structure (enthalpy; ∆H) of proteins. Comparisons are made between formulations as well as production lots, and differences in derived values indicate differences in thermal stability and structural conformation. Data illustrating the use of DSC in an industrial setting for stability studies as well as monitoring key manufacturing steps are provided as proof of the effectiveness of this protocol. In comparison to other methods for assessing the thermal stability of protein conformations, DSC is cost-effective, requires few sample preparation steps, and also provides a complete thermodynamic profile of the protein unfolding process.

  12. Polymorphism in nimodipine raw materials: development and validation of a quantitative method through differential scanning calorimetry.

    Science.gov (United States)

    Riekes, Manoela Klüppel; Pereira, Rafael Nicolay; Rauber, Gabriela Schneider; Cuffini, Silvia Lucia; de Campos, Carlos Eduardo Maduro; Silva, Marcos Antonio Segatto; Stulzer, Hellen Karine

    2012-11-01

    Due to the physical-chemical and therapeutic impacts of polymorphism, its monitoring in raw materials is necessary. The purpose of this study was to develop and validate a quantitative method to determine the polymorphic content of nimodipine (NMP) raw materials based on differential scanning calorimetry (DSC). The polymorphs required for the development of the method were characterized through DSC, X-ray powder diffraction (XRPD) and Raman spectroscopy and their polymorphic identity was confirmed. The developed method was found to be linear, robust, precise, accurate and specific. Three different samples obtained from distinct suppliers (NMP 1, NMP 2 and NMP 3) were firstly characterized through XRPD and DSC as polymorphic mixtures. The determination of their polymorphic identity revealed that all samples presented the Modification I (Mod I) or metastable form in greatest proportion. Since the commercial polymorph is Mod I, the polymorphic characteristic of the samples analyzed needs to be investigated. Thus, the proposed method provides a useful tool for the monitoring of the polymorphic content of NMP raw materials. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. Fibrinogen adsorption on zinc oxide nanoparticles: a Micro-Differential Scanning Calorimetry analysis.

    Science.gov (United States)

    Lousinian, S; Missopolinou, D; Panayiotou, C

    2013-04-01

    Understanding the interactions between proteins and surfaces (nanoparticles or films) is crucial for the fabrication and improvement of biomedical devices in direct contact with human blood. The aim of this work is the study of the interaction of fibrinogen (Fib) with zinc oxide nanoparticles. The nanoparticles were either synthesized chemically or were commercially available, having different size. Zinc oxide nanoparticles are known for their antibacterial properties, and Fib adsorption is studied in view of combining the antibacterial and desirable clotting behavior of a single material. The thermal properties of the Fib solution were studied by Micro-Differential Scanning Calorimetry. For the consideration of the compositional and structural properties of the nanoparticles, Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy were employed, respectively. Through the changes of the thermal properties of Fib upon adsorption that were observed by microDSC, the mechanisms of the protein adsorption were revealed. It seems that electrostatic (for the D and E domains) and hydrophobic interactions (for the aC chains) were responsible for the adsorption and the protein structural changes caused by it. The discrepancy between the Fib adsorption percentages on homemade and commercially available zinc oxide nanoparticles can be attributed to their different size. Copyright © 2013 Elsevier Inc. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

    Mertens, Jeffrey A., E-mail: Jeffrey.Mertens@ars.usda.gov [Bioenergy Research Unit, National Center for Agricultural Utilization Research, Agricultural Research Service, U.S. Department of Agriculture, 1815 North University Street, Peoria, IL 61604 (United States); Hector, Ronald E.; Bowman, Michael J. [Bioenergy Research Unit, National Center for Agricultural Utilization Research, Agricultural Research Service, U.S. Department of Agriculture, 1815 North University Street, Peoria, IL 61604 (United States)

    2012-01-10

    Highlights: Black-Right-Pointing-Pointer Thermodynamics of (GalpA){sub n} oligomers binding to an exo-polygalacturonase. Black-Right-Pointing-Pointer Energetics of binding (GalpA){sub n} were determined by ITC. Black-Right-Pointing-Pointer Thermodynamic parameters attributable to individual subsites were determined. - Abstract: 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 process that is enthalpically driven and results in extremely tight binding of the substrate to RPG16. Binding energies in combination with prior biochemical data suggests that RPG16 has the potential for five subsites, -1 to +4, with the greatest contribution to binding energies arising from subsite -1/+1. While the enthalpic contribution to binding decreases substantially for subsites +2 to +4, beneficial entropic effects occur in subsites +3 and +4 leading to increased total free energy as the length of oligomer increases. This information will be useful for additional studies in determining the binding contributions of specific amino acids with mutant enzymes.

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

    Science.gov (United States)

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

    2015-02-01

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

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

    CERN Document Server

    van Putten, Maurice H P M; Tagoshi, Hideyuki; Tatsumi, Daisuke; Masa-Katsu, Fujimoto; Della Valle, Massimo

    2011-01-01

    Observational evidence for black hole spin down has been found in the normalized light curves of long GRBs in the BATSE catalogue. Over the duration $T_{90}$ of the burst, matter swept up by the central black hole is susceptible to non-axisymmetries producing gravitational radiation with a negative chirp. A time sliced matched filtering method is introduced to capture phase-coherence on intermediate timescales, $\\tau$, here tested by injection of templates into experimental strain noise, $h_n(t)$. For TAMA 300, $h_n(f)\\simeq 10^{-21}$ Hz$^{-\\frac{1}{2}}$ at $f=1$ kHz gives a sensitivity distance for a reasonably accurate extraction of the trajectory in the time frequency domain of about $D\\simeq 0.07-0.10$ Mpc for spin fown of black holes of mass $M=10-12M_\\odot$ with $\\tau=1$ s. Extrapolation to advanced detectors implies $D\\simeq 35-50$ Mpc for $h_n(f)\\simeq 2\\times 10^{-24}$ Hz$^{-\\frac{1}{2}}$ around 1 kHz, which will open a new window to rigorous calorimetry on Kerr black holes.

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

    Science.gov (United States)

    Jing, Mingyang; Song, Wei; Liu, Rutao

    2016-07-01

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

  18. Magnetocaloric effect in Mn2-pyrazole-[Nb(CN)8] molecular magnet by relaxation calorimetry

    Science.gov (United States)

    Pełka, R.; Gajewski, M.; Miyazaki, Y.; Yamashita, S.; Nakazawa, Y.; Fitta, M.; Pinkowicz, D.; Sieklucka, B.

    2016-12-01

    Magnetocaloric effect in {[Mn(pyrazole)4]2[Nb(CN)8]·4 H2O}n molecular magnet is reported. It crystallizes in tetragonal I41/a space group. The compound exhibits a phase transition to a long range magnetically ordered state at TN ≈ 22.8 K. Temperature dependences of the magnetic entropy change ΔSM as well as the adiabatic temperature change ΔTad due to applied field change μ0 ΔH in the range of 0.1-9 T have been inferred from the relaxation calorimetry measurements. A systematic approximate approach has been used to determine the lattice contribution to the heat capacity. The maximum value of ΔSM for μ0 ΔH = 5 T is 6.83 J mol-1 K-1 (6.65 J kg-1 K-1) at 24.3 K. The corresponding maximum value of ΔTad is 1.4 K at 23.8 K. The temperature dependence of the exponent n characterizing the field dependence of ΔSM has been estimated. It attains the value of 0.64 at the transition temperature, which is consistent with the 3D Heisenberg universality class. A hitherto unobserved two-peak structure has been revealed in the temperature dependence of ΔTad.

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

    Science.gov (United States)

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

    2013-10-01

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

  20. A novel method for determining the solubility of small molecules in aqueous media and polymer solvent systems using solution calorimetry.

    Science.gov (United States)

    Fadda, Hala M; Chen, Xin; Aburub, Aktham; Mishra, Dinesh; Pinal, Rodolfo

    2014-07-01

    To explore the application of solution calorimetry for measuring drug solubility in experimentally challenging situations while providing additional information on the physical properties of the solute material. A semi-adiabatic solution calorimeter was used to measure the heat of dissolution of prednisolone and chlorpropamide in aqueous solvents and of griseofulvin and ritonavir in viscous solutions containing polyvinylpyrrolidone and N-ethylpyrrolidone. Dissolution end point was clearly ascertained when heat generation stopped. The heat of solution was a linear function of dissolved mass for all drugs (calorimetry offers a reliable method for measuring drug solubility in organic and aqueous solvents. The approach is complementary to the traditional shake-flask method, providing information on the solid properties of the solute. For highly viscous solutions, the calorimetric approach is advantageous.