Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:4.1.2.42 (DTA)
 1,693 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The results obtained by macro-DTA were not reproducible because they were largely influenced by the packing method, the amount of samples and many other factors related to each apparatus. The dehydration process of gypsum was investigated by micro-DTA in this study. The results were compared with those of macro-DTA studies. Two endothermic peaks were generally observed. These peaks tended to overlap with the increase of particle size. As the water vapor pressure decreased, the two peaks shifted to lower temperature and finally overlapped completely. The effect of the amount of samples was very similar to that of the atmosphere. When the amount was less than about 1 mg, only a single peak was observed. The dehydration process of gypsum was discussed on the basis of a phase diagram of the system of CaSO4-H2O. Moreover, the activation energies of the first and second dehydration reactions were calculated by Kissinger's method. The former was about 25 kcal/mol and the latter was about 24 kcal/mol. They werein good agreement with those obtained by other workers.
 ...
PMID:[Re-examination of dehydration process of gypsum by micro-DTA (author's transl)]. 28 85

This paper discusses the role played by the "WLF decrease in viscosity" above the temperature of the glass transition (Tg) in the temperature dependence of the stability of frozen foods. In the first part, the complex features observed before the melting endotherm on DSC/DTA thermograms of sugar-water solutions are examined; they are suggested to be representative of a glass transition associated with enthalpy relaxation. In the second part, the values of Tg for some complex foods are discussed. It is shown that ice melting adds an important contribution to the WLF effect on the decrease of the viscosity of the freeze-concentrated phase. The temperature dependence of the deterioration processes observed in frozen food products is generally smaller than that expected from this viscosity decrease. Several hypotheses are presented to account for the discrepancy.
 ...
PMID:DSC studies and stability of frozen foods. 174 24

The title coordination compound has been synthesized by the reaction of HLaEDTA.7H2O with (formula; see text) in ethanol aqueous solution. The single crystal has grown from aqueous solution and has been characterized by IR, TG-DTA, X-ray powder diffraction, molar conductance, UV and 1H-NMR. The determination of its crystal and molecular structure shows that it crystallizes in space group P21/n with lattice parameters: a = 14.735A, b = 29.335A, c = 16.409A, beta = 99.24 degrees, v = 7009.30A3, z = 4, F(000) = 3488, molecular weight M = 1756.90, Dc = 1.665g/cm3. It has been refined by the full matrix least squares method to final discrepancy factor R = 0.096. The anion [La2(EDTA)2(H2O)4]2- turns out to be a dimer, in which each of the two EDTA4- ions is coordinated to a La3+ ion with five of its six coordinating sites and the remaining sixth one--the oxygen atom of carboxylis bridged to two La3+ ions, thus forming a parallelogrammic four-membered ring La2O2. The nine coordinations about each metal are completed by two water molecules. The average bond length is 2.560 A for La-O and 2.833A for La-N. Approximately, the dimer belongs to point group Ci with the centre of inversion at the centre of La2O2 parallelogram. The antitumor activity of the coordination compound was studied by observing its effect on the incorporation of 3H-TdR into DNA of leukemia (L7712) cells in vitro. The degree of inhibition reached 83.9% after exposing 2 X 10(5) cells per millilitre to 4 X 10(-5) mol/L of the compound for 24 h, being higher than those of its precursors.
 ...
PMID:Study on some biologically active coordination compounds of metal ions (I)--Synthesis, characterization, structure and antitumor activity of complex of 3,6-di-(dimethylamino)-dibenzopyriodonium lanthanum EDTA. 261 Aug 65

(Cu(CM)A)B(C6H5)4 and Cu(CM)A(OH) X H2O (CM = cimetidine and HA = L-alanine) were prepared and characterized by elemental analysis, TG-DTA, IR, and electronic spectral data and magnetic susceptibility measurements. The EPR spectrum of (Cu(CM)A)B(C6H5)4 shows a distorted octahedral environment for the Cu(II) ion.
 ...
PMID:Ternary complexes of Cu(II) ion with cimetidine and L-alanine. 303 Dec 10

The complex formation equilibria of Zn(II) and Cd(II) with cephalexin have been studied through potentiometric titrations. Experimental data were analyzed using the least squares computer program SUPERQUAD. The stability constants were 1g beta ZnCEX+ = 2.40, 1g beta Zn(CEX)(OH) = -4.54, 1g beta CdCEX+ = 2.18, and 1g beta Cd(CEX)(OH) = -5.18 (I = 0.1 M NaNO3), CEX complexes of formulae Zn(CEX)2(3)H2O and Cd(CEX)(OH)H2O have been synthesized and characterized by elemental analysis, IR spectra, conductivity measurements, and electronic and NMR spectra. The thermal behavior of the synthesized compounds were studied by TGA and DTA. We conclude that the metal ion interacts with the amido group of CEX.
 ...
PMID:Antibiotic as ligand. Coordinating behavior of the cephalexin towards Zn(II) and Cd(II) ions. 343 Jan 51

Sulfatides are membrane-bound glycosphingolipids which tend to associate in micellar forms in water. In this study, combining the data obtained by several techniques, including 31P-NMR, DTA calorimetry, freeze-fracture electron microscopy, trapped volume and turbidity measurements plus enzymatic determination of outer-side "marker ganglioside", have enabled us to establish that bilayered liposomes of phosphatidylcholine formed in the presence of increasing amounts of sulfatide are stable up to 30 mol % glycolipid. Above thus, bilayered lipids progressively start to break up into micellar forms with bilayer-micelle transition complete at sulfatide concentrations above 80 mol %. The gel-to-liquid-crystalline phase transition of a dipalmitoylphosphatidylcholine-sulfatide dispersion is shown to strongly influence the equilibrium between micellar and bilayered forms, the micelles being present at higher concentrations as the fluidity of the system decreases. The possibility that such structural transitions may occur in vivo and effectively contribute to the modulation of some biological properties of the membranes is discussed.
 ...
PMID:Bilayer-micelle transition in phosphatidylcholine-sulfatide mixtures. 652 41

The setting reactions and thermal degradation of the phosphate binders are interpreted from the DTA and X-ray diffraction data. Setting takes place through complex formation of (NH4Mg PO4.6H2O)n, excess reactants, and water. Dehydration and thermal reactions lead to a sequence of reactions forming (NH4MgPO4.H2O)n, (Mg2P2O7)n, Mg2P2O7, and Mg3(PO4)2.
 ...
PMID:Setting and thermal reactions of phosphate investments. 693 Nov 24

Thermal behavior of MgNH4PO4.6H2O was investigated by means of TG-DTA and X-ray diffraction. Two endothermic peaks (90 degrees C and 230 degrees C) and a exothermic peak (660 degrees C) were observed in a micro-DTA curve. Weight loss occurred at two stages corresponding to the two endothermic peaks. Values of weight loss were about 38% and 53%, respectively, at the end of each stage. These values were nearly equal to theoretical weight losses in the formation of Mg2P2O7 from MgNH4PO4.6H2O via MgNH4PO4.H2O. The intermediate, MgNH4PO4.H2O was identified by X-ray diffraction. The second weight loss continued till about 600 degrees C. The product during the second stage was amorphous and Mg2P2O7 began to crystallize above about 600 degrees C. The exothermic peak was thought to correspond to the crystallization. On the other hand, the first endothermic peak separated into two peaks in a macro-DTA curve. The first corresponded to removal of crystal water from MgNH4PO4.6H2O and the second to evaporation of the condensed water. Moreover the exothermic peak also separated into two peaks and the peak temperatures lowered. It was considered that the crystallization was affected by the atmosphere.
 ...
PMID:[Thermal behavior of phosphate-bonded investment. Part 1. Thermal behavior of MgNH4PO4.6H2O (author's transl)]. 695 96

Reaction process in the equimolar mixtures of MgO-MgNH4PO4.6H2O and MgO-NH4H2PO4 were investigated by TG-DTA and X-ray diffraction. In the MgO-MgNH4PO4.6H2O system, MgNH4PO4.6H2O was changed by heating in the following way. The formation of MgNH4PO4.H2O by dehydration about 100 degrees C and of amorphous Mg2P2O7 by dehydration and removal of NH3 above 200 degrees C and the crystallization of Mg2P2O7 above 600 degrees C. A part of the amorphous Mg2P2O7 reacted with MgO to form Mg3(PO4)2 above 600 degrees C. The crystallized Mg2P2O7 also reacted with MgO to form Mg3(PO4)2 at higher temperature. In the MgO-NH4H2PO4 system, MgNH4PO4.H2O was formed by the reaction between them, which was corresponded to an exothermic peak about 140 degrees C in the DTA curve. MgNH4PO4.H2O, an unknown phase Y and an amorphous phase were formed at 200 degrees C. The crystalline phases almost disappeared and another unknown phase X appeared at 300 degrees C. The phase X also disappeared and Mg(PO3)2 appeared at 400 degrees C. In the TG-DTA curve for this system, an exothermic peak, which was corresponded to crystallization of Mg(PO3)2, was observed about 550 degrees C and the decomposition of NH4H2PO4 ceased after the crystallization. Mg(PO3)2 reacted with MgO to form Mg2P2O7 at higher temperature.
 ...
PMID:[Thermal behavior of phosphate-bonded investment. Part 2. Reactions in the systems of MgO-MgNH4PO4.6H2O and MgO-NH4H2PO4 (author's transl)]. 695 99

Main applications of modern thermal methods in the pharmaceutical analysis are reviewed. While these methods are widely employed in pharmaceutical industry, they are only recommended--but not prescribed--in the general part of the VIIth Pharmacopoea Hungarica and consequently, this field is practically unknown for the pharmacists. The aim of this paper is to call attention to the advantage of the application of modern thermal methods (DTA, TG, DSC) in contrast to the classical ones. They permit a quick and accurate measurement of the melting point, the determination of purity and eutectic point, to clear up the possibility of conditions for the development of polymorphic modifications, and to follow the process of loosing the water of crystallization.
 ...
PMID:[Application of modern thermal methods in pharmaceutical analysis]. 802 86


1 2 3 4 5 6 7 8 9 10 Next >>