Search results for "calor"
showing 10 items of 866 documents
Hypertriglyceridemia and Omega-3 Fatty Acids
1988
Recent studies by Bang and Dyerberg (1) have stimulated interest in the metabolism of omega-3 fatty acids and have suggested a link between the ingestion of these fatty acids in a diet and the low death rate from athersclerotic disease in Eskimos. In Japan, where fish consumption has traditionally been high, a concommitant shift in tissue lipid consumption favouring omega-3 polyunsaturated fatty acids has been interpreted as causative of a relatively low incidence of cardiovascular disease (1). When analyzing Eskimo food consumption, it became clear that the consumption of omega-3 PUFA is much higher besides a 50% reduction of saturated fat and a relatively high content of monounsaturated f…
Influence of Polymer Molecular Weight on Drug–polymer Solubility: A Comparison between Experimentally Determined Solubility in PVP and Prediction Der…
2015
ABSTRACT: In this study, the influence of polymer molecular weight on drug–polymer solubility was investigated using binary systems containing indomethacin (IMC) and polyvinylpyrrolidone (PVP) of different molecular weights. The experimental solubility in PVP, measured using a differential scanning calorimetry annealing method, was compared with the solubility calculated from the solubility of the drug in the liquid analogue N-vinylpyrrolidone (NVP). The experimental solubility of IMC in the low-molecular-weight PVP K12 was not significantly different from that in the higher molecular weight PVPs (K25, K30, and K90). The calculated solubilities derived from the solubility in NVP (0.31–0.32 …
Influence of functionalization on interaction and drug release from α,β-polyaspartylhydrazide derivatives to a biomembrane model: evaluation by diffe…
2004
Abstract A comparative study on the ability of various polymers to interact with a biomembrane model was carried out by differential scanning calorimetry (DSC). The investigated samples were a water soluble polymer, the α,β-polyaspartylhydrazide (PAHy) and its derivatives containing polyethylene glycol (PEG2000) (sample PAHy–PEG2000), or hexadecylamine (C16) (sample PAHy–C16) or both compounds (sample PAHy–PEG2000–C16). Some samples are able to arrange themselves as micellar structures and to interact potentially with the membrane surface so as to favor the release of the drug near the target membrane and consequently to improve drug adsorption processes. First, the interaction of all polym…
Thermodynamics of cyclodextrin-star copolymer threading-dethreading process
2015
We investigated the interactions of a star-like copolymer with cyclodextrins (CD) with different cavity size. Direct measurements of thermodynamic properties were done, and the application of proper molecular models was useful for the interpretation of the involved phenomena. The CD–copolymer inclusion complexes were characterized by isothermal titration calorimetry. The copolymer aggregation induced by temperature was investigated by differential scanning calorimetry, volume and compressibility measurements. The behavior of the ternary T1107/CD/water mixture was interpreted considering competing equilibria. The investigated systems showed an interesting temperature responsive behavior so t…
Vitrification of polymer solutions as a function of solvent quality, analyzed via vapor pressures.
2006
Vapor pressures (headspace sampling in combination with gas chromatography) and glass transition temperatures [differential scanning calorimetry (DSC)] have been measured for solutions of polystyrene (PS) in either toluene (TL) (10-70 degrees C) or cyclohexane (CH) (32-60 degrees C) from moderately concentrated solutions up to the pure polymer. As long as the mixtures are liquid, the vapor pressure of TL (good solvent) is considerably lower than that of CH (theta solvent) under other identical conditions. These differences vanish upon the vitrification of the solutions. For TL the isothermal liquid-solid transition induced by an increase of polymer concentration takes place within a finite …
Organometallic ABC-triblock copolymers
1998
The interaction of Fe and Pd complexes with double bonds of the polybutadiene (PB) block in polystyrene-polybutadiene-poly(methyl methacrylate) block copolymers has been studied. The incorporation of Fe(CO)3 fragments into the PB bloc was found to result in an increase in its rigidity. The presence of iron or palladium complexes in the PB block affects strongly the morphology of the triblock copolymers.
Simulation of Metabolism for The Calculation of Enzyme Activities in Stress Metabolism
1988
Abstract Using data of indirect calorimetry, total energy turnover as well as the rate of combustion of carbohydrates, fat and amino acids can be calculated. For the evaluation, simple standard procedures (4) are used. These procedures presume, that several assumptions are satisfied, e.g. a complete degradation of the energy delivering substrates and undisturbed enzyme activities. To be able to interprete also measurements, which are performed in the post-traumatic state as well as for estimation of the extent and consequences of reduced enzyme activities, a new method for the simulation of metabolism was developed. Hie underlying model considers a reduced activity of key enzymes and a swit…
Self-assembly of fluorescent diimidazolium salts: tailor properties of the aggregates changing alkyl chain features
2016
Searching for new fluorescent organic salts to be used in biomedical and electrochemical field, we conjugated properties of imidazolium salts with the ones of naphthalene diimide core and we obtained some N,N′-bis-(1-alkyl-3-propylimidazolium)naphthalene diimide diiodides. We took into account alkyl chains going from hexyl to dodecyl, as well as hydrogenated and fluorinated alkyl tails. After determination of their thermal behaviour by differential scanning calorimetry, concentration-, and temperature-dependent spectroscopic studies (UV-vis and fluorescence) were performed evidencing the occurrence of isodesmic and enthalpy-driven self-assembly processes. Properties of aggregates were also …
Anion coordination chemistry in aqueous solution of polyammonium receptors
2006
The behavior of polyamines as receptors of selected families of anions in water is explored. First metallocyanide interaction with saturated polyammonium hosts is analyzed both in solution and in the solid state. The utility of potentiometry, multinuclear NMR, microcalorimetry and cyclic voltammetry to describe solution features of this chemistry is described for selected systems. Sulfate, phosphate, polyphosphate and nucleotide interactions with large polyammonium receptors are then reviewed. Hydrogen bond formation is discussed from a thermodynamic point of view. The influence of the presence of aromatic fragments within the structure on the binding strength is discussed. Factors affectin…
Kinetics of Molecule Transfer between Lipid Vesicles and β-Cyclodextrins
1996
Abstract We propose a calorimetric method based on the van't Hoff model of depression of the freezing temperature to investigate slow kinetics involving lipid vesicles (liposomes) and drug–β-cyclodextrin (Cyd) complexes. Some nonsteroidal antiinflammatory drugs (NSAIDs) were examined and standard phospholipid liposomes were used in our experiments. Three different kinetic processes were investigated: (a)9Transfer of drugs from water-soluble Cyd-complexes to void liposomes. (b)9Uptake of drugs from the surface of liposomes by free Cyd dissolved in the aqueous phase. (c)9Exchange of drugs from loaded to void vesicles, and the effect of free Cyd in enhancing such a transfer. Most experiments w…