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Abstract  

Solid amorphous mixed zirconium-titanium phosphates, with general formula ZrxTi/1–x//HPO4/2.n H2O/ where x=0.1–1, and n=3–5/, are mixed with an excess of solid oxalic acid dihydrate and digested in molten oxalic acid. Then oxalic acid is removed by extraction and the residue washed with dilute /O.OlM/ HCl solution and bidistilled water. As a result of this method, crystalline mixed zirconium-titanium phosphate is formed.

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Abstract  

Integral electron Mössbauer spectroscopy (ICEMS) and additionally some electrochemical methods were used to characterize the passivation process of iron (low carbon steel) in sulfate, sulfate+sulfite (a possible model solution of acid rain) solutions and in phospate buffer. The phase compositions and thicknesses of the passive layers formed due to the electrochemical polarizations were analyzed in dependence on the duration of the anodic passivations and on the pH of the used electrolytes. The passive layer, as determined from the Mössbauer spectra, consists mainly of -FeOOH, however in sulfite containing sulfate aqueous solution at pH 3.5 Fe3C and despite ex-situ circumstances FeSO4·H2O was detected after the shortest polarization time. The film thickness, which was found to grow nearly linearly with polarization time in pure sulfate solution and in phospate buffer, reached a maximum of 60–160 nm (depending on pH) in sulfate+sulfite solution after a passivation time of about 4 hours. It has been proved, that HSO3 -ion, which is contained by acid rain, initiate pit formation under acid conditions and so enforces the corrosion of iron. The experimental results furthermore suggest, that not the whole oxidic layer is responsible for the passivity but only a very thin intermediate layer formed between an inner oxide layer of a cubic structure and the rhombic oxide (-FeOOH) cover.

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Abstract  

The kinetics of chromate coating formation and chromium(VI) exchange has been studied by of novel continuous radiotracer method. Comparison has been made with former results obtained by a quasi-continuous procedure and kinetic constants have been determined.

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Abstract  

The activation energy values of cyclohexane dehydrogenation and hydrogenolysis on alumina supported Ni, MoOx and three NiMoOx samples of different Ni:Mo ratio have been determined. Applying these values and the activation energies determined before for thiophene hydrodesulfurization on these catalysts, the C-Cat, H-Cat and S-Cat bond strengths were calculated. The bond strengths C-Cat and S-Cat are significantly higher for the samples of higher catalytic activity [NiMo(0.35) and NiMo(0.6)] in comparison with those of the less active ones [NiMo(0.15) and Ni12]. Compensation plots between Arrhenius constants indicate equal site distribution for the three reactions.

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Summary  

A highly efficient and an optimized synthesis of [1-14C]lauric acid with high specific activity (50 mCi/mmol) is described. [1-14C]lauric acid was prepared from [1-14C]lauronitrile, in 2 minutes with a mixture of concentrated hydrochloric acid: propionic acid (1: 2 v/v) under microwave irradiation, in quantitative yield.

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Summary  

Hydrophilic endohedral 133Xe-fullerenols, [133Xe@C60(OH)xand 133Xe@C70(OH)x], were synthesized from hydrophobic endohedral 133Xe-fullerenes. The yield of endohedral 133Xe-fullerenols extracted in water was about 40% and 23% for C60and C70, respectively. The products stored in 0.9% NaCl solution at 20 °C were stable enough to be used in nuclear medicine.

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Abstract  

The parallel plate avalanche counter (PPAC) built in our laboratory was used to measure the CEM spectra of iron electrodeposited over a steel substrate. The electron counter was operated with ketone gas inside the ionization chamber, at a pressure of 34 torr, and an applied voltage of 650V, with the purpose of showing the depth profile of CEM spectra. These spectra were measured by selecting the energy range of reemitted electrons. It was demonstrated that the PPAC in this configuration can be used to identify the chemical species formed at different depths from the resonator surface. This method was applied to the oxidation of iron in two different environments.

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Abstract  

The operating principle of a memory based radiation sensor, which is the Soft Error mechanism in silicon integrated circuits was suggested in our research with particular reference to dynamic Random Access Memories (dRAMs), with a view of employing it in neutron detection, imaging and elemental analysis. Thus, having initially proved that dRAMs can be used as heavy charged particle detectors, it was thought that these devices can be made sensitive to neutrons by adding a foil to convert the thermal neutrons to charged particles through the (n,) reaction. In order to further evaluate the feasibility of this approach, a Monte Carlo program has been used to simulate and examine suitable converting materials with respect to soft error generation and to determine methods to increase the sensitivity of dRAMs to neutrons. The aim of this paper is to present results from these calculations and discuss the capabilities of such a neutron detector.

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Summary Thermogravimetry (TG) and Me2CO adsorption measurements for flexible porous crystalline coordination polymers with 2-dimensional (2-D) frameworks, {[Co(NCS)2(3-pia)2]·4Me2CO}n (1⊃4Me2CO, 3-pia=N-(3-pyridyl)isonicotinamide), were carried out. Taking advantages of capability of hydrogen bonding of amide groups for a dynamic properties, 1⊃4Me2CO show crystal (non-porous)-to-crystal (porous) structural rearrangement in Me2CO adsorption/desorption processes. The activation energy for the Me2CO desorption process of 1⊃4Me2CO was obtained using Flynn-Wall-Ozawa’s (FWO) method. The Me2CO adsorption isotherms on 1 have a threshold pressure (P th) for abrupt accommodation of Me2CO molecules, which is regarded as the equilibrium pressure for the inclusion reaction of Me2CO

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