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Abstract  

Pyrrolidyl triazenes prepared by interception of the diazonium transient in the Sandmeyer reaction of amines can serve as useful intermediates in the iodination and radioiodination of aryl rings. Decomposition of such triazenes in the presence of iodide is acid-catalyzed and is sensitive to choice of solvent, acid, and triazene structure. A condition variation study by HPLC of four different solvent systems and two non-nucleophilic acids was carried out on the123I iodination of the triazenes of p-nitroaniline, p-anisidine and p-toluidine. This method has proven useful in radiolabeling of two pharmaceutical analogs which were not amenable to labeling through the classic Sandmeyer method.

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Abstract  

Problems connected with quantitative EDXRF analysis of intermediate thickness samples are addressed. The first one is a systematic study of the various contributions to the total error of the E-T method. Special attention is also given to the enhancement effect for intermediate thickness samples; in this context both monochromatic and bichromatic approaches are adapted to a known theoretical model.

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Abstract  

An improved method based on the moderation of intermediate neutrons for the measurement of hydrogen in small samples is described. With the aid of boron and cadmium filters, a space shielded from slow neutrons is set up close to an isotopic neutron source shrouded by water moderator. A BF3 proportional counter enclosed with a sample cell is placed in this space. The neutron count rate of the counter increases when a hydrogen-containing material is introduced into the cell, due to the moderation of intermediate neutrons passing through the filters. With a 1.3 μg252Cf neutron source, the lower limit of hydrogen detection for 200 ml samples in 10 min count time is 0.01 wt.%. This method is suitable for measuring the H2O content of heavy water.

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When the components of a reaction mixture cannot be quantified by UV-visible spectrophotometry, because the λ max values of their absorption bands overlap, the components can be separated and quantified by spectrodensitometric thin-layer chromatography (SDTLC). In this work an aminolysis reaction mixture in aqueous medium was studied by TLC on silica gel plates with densitometric detection. The reaction, an intramolecular rearrangement involving migration of an acyl group, was studied by monitoring a carbinolamine intermediate for which λ max was identical with those of the substrate and product. SDTLC not only enabled detection of all three components of the mixture when the plate was developed but also enabled detection of covalent and ionic forms of the reaction intermediate by comparison of their absorbance/reflectance spectra with those of structurally related imidazolidine and amidinium salt derivatives, respectively, used as model compounds. Kinetic studies, among others, may also be performed by SDTLC to determine the mechanism of the reaction.

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Abstract  

A method of measuring heavy water concentration is described based on intermediate neutron moderation. With a 1.6 g252Cf neutron source and a BF3 proportional counter, for 500 ml samples, accuracies of the measurements are within ±0.02 mol% in the concentration range of 0100 mol% with 210 minute counting. To evaluate the practical effectiveness of the method, a model apparatus was built for routine use in laboratory and on-stream measurements. It was successfully applied to observe the substitution process between light water and heavy water in an ion exchange resin tower at a nuclear power station.

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Summary The heat capacity of contractile proteins actin and myosin was studied in psoas muscle of rabbit in strongly and weakly binding state of myosin to actin as a function of temperature by DSC. Deconvolution of the unfolding scans makes possible to characterize the structural domains of the macromolecules. We tried to approach the unfolding process in different intermediate state of ATP hydrolysis. The thermal transitions were calorimetrically irreversible, therefore the two-state irreversible model that describes fairly well the denaturation of different proteins was used for evaluation of the denaturation processes in muscle fibers in strongly (rigor, ADP) and weakly binding states (ATP·Vi, ADP·AlF4) of myosin to actin. Deconvolution resulted in four transitions, the first three transition temperatures were almost independent of the intermediate states of muscle, the last transition temperature was shifted to higher temperature, when the buffer solution was manipulated. The mean values in strongly binding states were Tm1=52.9±0.7°C, Tm2=57.9±0.7°C, Tm3=63.7±1.0°C and Tm4=67.8±0.7°C, but the last transition increased to higher temperature depending on the Pi analogue.

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A relatively simple strategy is described for the thermal hazard screening of isolated synthetic intermediates and products, as employed within the Research Division of a major pharmaceutical company.

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Abstract  

Hydrated iron oxide or amorphous-Fe2O3·3.5 H2O (HFeO), hydrated titanium oxide (HTiO) and hydrated thorium oxide (HThO) were synthesized and their applicability for the decontamination of intermediate level liquid wastes (ILLW) was tested. The sorption of a few actinides like plutonium and americium on HFeO, 137Cs and 106Ru on HTiO and 90Sr on HThO was investigated as a function of pH, time and loading capacity of the hydrous oxide with metal ions. The influence of the total dissolved salt content was also monitored. Some of these parameters influenced the sorption behavior significantly. The radiation stability of these inorganic sorbents were studied by irradiating them up to 48 Mrad. Adsorbed actinides and fission products were successfully eluted from HFeO and from the mix-bed of HTiO and HThO by 0.5M nitric acid.

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Abstract  

Zirconyl tungstate ceramic-supported membranes were developed and characterized. The transport process of Cs(I), Sr(II) and La(III) from the anode compartment to the cathode was investigated. The cationic fluxes for Cs(I), Sr(II) and La(III) were found to be 9·10–10, 2.7·10–9 and 2.4·10–9 g·eq·cm–2·s–1, respectively. The transport numbers of these cations were found to be 0.12, 0.07 and 0.09, respectively. Separation of Cs(I), Sr(II) and La(III) was achieved using EDTA as a chelating agent in the anode compartment. Cs(I) was successfully separated with a decontamination factor of 97% from simulated intermediate level liquid waste (ILLW) containing Cs(I) and Sr(II).

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The kinetics of thermal decomposition of iron(II) sulphate hexa- to monohydrates, as well as the hydroxy- and oxysulphates of iron(III), are presented and discussed. The results confirm that the final intermediate that decomposes to iron(III) oxide and sulphur trioxide during the thermal decomposition of any hydrate of iron(II) sulphate is the oxysulphate, Fe2O(SO4)2.

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