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England in years 1973–1974) CACs are applied to structural concrete much less often than Portland cements [ 1 – 3 ]. The deterioration of strength is related with a process of conversion of aluminate hydrates. In case of CACs the nature of hydration
Introduction The kinetics and mechanism of hydration in various cementitious systems can be investigated by use of calorimetry [ 1 – 5 ]. The heat evolution curve reflects the rate of reactions occurring in the hydrating system
this way one may obtain a new binder of improved and/or changed properties. It is the effect of action of active additives that influence physical and chemical processes and arising products of hydration. The main products of hydration of
Introduction The dehydration of Portland cement paste plays an important role in the concrete structure explosive spalling at fire. Calcium silicate hydrate (CSH) and calcium hydroxide (CH) are the main hydration phases which
Abstract
Reactions in aqueous-alcoholic solution between diphenyl-4-amine barium sulphonate (Ba-DAS—anionic surfactant) and the hydrated sulphates of Fe(III) and Fe(II) ions and their use to ovtain iron oxides are described here. The formation of Fe(II) complexes was reached by using an excess of Ba-DAS, in absence of light under inert atmosphere. The complexes achieved Fe2[(C12H10NO3S)4]·9H2O and Fe3[(C12H10NO3S)6]·12H2O were characterized by TG/DTG and IR, UV-VIS and 57Fe-Mössbauer analyses.
Abstract
A method for the determination of uranium and 210Po in high salinity water samples has been elaborated. Both radionuclides are preconcentrated from 0.5 dm3 saline media by co-precipitation with hydrated manganese dioxide, followed by dissolution of the precipitate in 200 mL of 1 M HCl. Uranium isotopes 235U and 238U can be directly determined by ICP MS method with a detection limit of 0.01 ppb for 238U. Prior to a selective determination of 210Po, the majority of other naturally occurring α-emitting radionuclides (uranium, thorium and protactinium) can be stripped from this solution by their extraction with a 50% solution of HDEHP in toluene. Finally, 210Po is simply separated by direct transfer to an extractive scintillator containing 5% of trioctylphosphine oxide in Ultima Gold F cocktail and determined by an α/β separation liquid scintillation technique with detection limit below 0.1 mBq/dm3.
Abstract
Pyridine-2,5-dicarboxylic acid, known as isocinchomeric acid is one of six isomers containing two carboxylic groups. Light lanthanide (III) complexes with pyridine-2,5-dicarboxylic acid with general formula Ln2L3·nH2O, where n = 8, 9, were obtained. Their thermal and spectroscopic properties were studied. Sodium salt was obtained as Na2L·H2O. Hydrated complexes of La(III), Ce(III), Pr(III), Nd(III), Sm(III), Eu(III) and Gd(III) are stable to 313–333 K, whereas Na2L·H2O is stable to about 333 K. Dehydration process for all compounds runs in one stage, next they decompose into appropriate lanthanide oxalates, oxocarbonates carbonates and finally to metal oxides. Bands of νCOOH vibrations at 1736 and 1728 cm−1 disappear on complex spectra and νas and νs of COO− groups appear thus indicating that complexation process took place.
as a structuring and foaming agent as an egg white substitute ( Stasiak et al., 2023 ). When processing dried pulses, it is important to keep the crop hydrated. This process can range from 3 to 4 or even up to 10–12 h. Adequate water uptake is
pharmacokinetics. Experimental Materials Toddalolactone and oxypeucedanin hydrate (IS) (both purity >98%) were obtained from Chengdu Munster biotechnology Co. Ltd (Chengdu, China). HPLC-grade formic
general, such behavior is frequently observed for the aqueous solutions of ionic surfactants [ 8 , 9 , 12 ]. It is a resultant of two opposing effects which influence the micellization process. The first effect is connected with the hydration of polar