Results 251 to 260 of about 5,226 (300)
Some of the next articles are maybe not open access.
Anion exchange in acetic acid solutions
Analytica Chimica Acta, 1971Abstract The adsorbabilities of 65 elements in water-acetic acid medium on the anionexchanger Dowex 1-X8 have been investigated in the region 2–17.4 M acetic acid. Examples of possible individual separations of elements are given, namely : Cu-Zn, Mn-Cu-Zn, Na-As-Cu and U-Np. A separation of the elements Ag, As, Au, Br. Co, Cu, K, Mn, Mo, Na, Sc and
S.K. Jha, F. De Corte, J. Hoste
openaire +1 more source
Deuterium exchange during acid-demineralisation
Geochimica et Cosmochimica Acta, 1988Isotopic analyses of residues prepared by demineralisation of the Murchison meteorite using D-labelled reagents provide evidence for measurable exchange of H-isotopes between residue and reagents. Precise quantification of this effect is precluded by substantial inhomogeneity of the meteoritic organic matter.
J F, Kerridge, S, Chang, R, Shipp
openaire +2 more sources
Exchange reactions and phosphoglyceric acid in photosynthesis
Archives of Biochemistry and Biophysics, 1952Abstract Experiments have been described in which total fixation of carbon dioxide in short periods of photosynthesis has been studied simultaneously with the fixation in the carboxyl of phosphoglyceric acid. These kinetic studies have shown that the labeling of phosphoglyceric acid represents a step in the photosynthetic process and is not due to an
E W, FAGER, J L, ROSENBERG
openaire +2 more sources
Enzymatic fatty acid exchange in digalactosyldiacylglycerol
Chemistry and Physics of Lipids, 2000Six different lipases were screened for their ability of acidolysis between digalactosyldiacylglycerol (DGDG) and heptadecanoic acid in toluene. Lipases from Geotrichum candidum, Alcaligenes sp. and Penicillium camembertii did not catalyse the acidolysis reaction.
M, Persson, I, Svensson, P, Adlercreutz
openaire +2 more sources
Deuterium exchange in arsenobetaine and dimethylarsinoylacetic acid
Journal of Inorganic Biochemistry, 2005Arsenobetaine occurs naturally in almost all marine animals and it is assumed to be the unreactive end-product of a detoxification pathway. To investigate the properties of arsenobetaine and its likely immediate biogenic precursor, dimethylarsinoylacetic acid, we studied the exchanges of the C-2 methylene protons of these compounds in D2O solution and ...
John S, Edmonds +2 more
openaire +2 more sources
Ion-Exchange Equilibria of Amino Acids on a Strong Acid Resin
Industrial & Engineering Chemistry Research, 1996The exchange equilibria of several amino acids, with particular emphasis on those displaying two basic groups, on a strong-acid cation exchange resin (Amberlite IR120) are investigated. The behavior of the experimental data is described through a mathematical model which takes into account the dissociation equilibria of amino acids in aqueous solution,
S. Melis +3 more
openaire +3 more sources
THE ISOTOPIC EXCHANGE OF FLUOROBORIC ACID WITH HYDROFLUORIC ACID
The Journal of Physical Chemistry, 1960The isotopic exchange rate of fluorine between fluoroboric and hydrofluoric acids was investigated. The rate of exchange R = 4.5 x 10/sup -4/ e/ sup -24//sup .70//sup 0// /sup RT/ STABF/sup -//sub 4/!STAH/sup +/! liters mole/ sup -1/ sec/sup -1/. The exchange was found to proceed via HBF/sub 4/ = HF + BF/ sub 3/.
M. Anbar, S. Guttmann
openaire +1 more source
Acid deuterium exchange in benzazoles
Chemistry of Heterocyclic Compounds, 1986The kinetics of acid deuterium exchange in benzazoles carrying electron-donor substituents in the 5-, 6-, or 7-positions have been studied. Mass spectrometric studies have shown that exchange in 5-methoxy-1, 2-dimethylbenzimidazole takes place exclusively at one position in the benzene ring, in 5-chloro-, 7-chloro-,5-methoxy-2-methylbenzothiazole and 6-
I. F. Tupitsyn +3 more
openaire +1 more source
Kinetics and modeling of fatty acids esterification on acid exchange resins
Chemical Engineering Journal, 2010Abstract Biodiesel, a renewable fuel of vegetal origin, has been an object of a rapidly growing interest, in the latest years, both as a pure fuel and as blending component to reduce exhaust pollutants of traditional diesel fuel. Biodiesel is conventionally produced through a well-established technology that involves the use of alkaline catalysts and
TESSER, RICCARDO +4 more
openaire +2 more sources
Acid exchange resins deactivation in the esterification of free fatty acids
Chemical Engineering Journal, 2010In this work the deactivation of an ionic exchange resin, used as catalyst for promoting the esterification of fatty acids for producing biodiesel, has been studied. At this purpose, a dynamic mathematical model, suitable to describe the performances of a continuous tubular reactor containing the catalysts mixed with stainless steel springs as inert ...
TESSER, RICCARDO +5 more
openaire +3 more sources