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Abstract  

Carbon nanotubes (CNTs) were synthesized using a chemical vapour deposition (CVD) method. The properties of CNTs before and after vacuum annealing treatment were studied using scanning electron microscopy (SEM), scanning tunneling microscopy/spectroscopy (STM/STS) and thermogravimetric analysis (TG). Field emission characteristics of the raw and vacuum heated (up to 650C) carbon nanotube films (CNTFs) were measured in a diode system. Emissive properties of the CNTFs depend on an annealing process during which structural changes in the nanotube walls take place. The structural changes, related to saturation of dangling bonds, influence a rate of oxidation process and also improve the emissive field properties.

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Abstract  

The influence of thermal treatments on photoluminescence spectra of several minerals has been investigated. By applying step-wise heating, new luminescence centres were detected which had been not previously recognized in the corresponding minerals. Luminsecence centres appearing as result of valence changing during oxidizing heating include: (i)  (UO2)2+ as a result of nonluminescent U6+ transformation in zircon, barite, francolite and chert; (ii)  Eu2+ as a result of nonluminescent Eu+ transformation in barite. Luminescence centres which were most stable under thermal treatment were Fe3+ in zircon and Mn2+ in barite. Luminescence centres with similar spectral-kinetic properties but with different thermal stability which allowed them to be separated and properly identified were different metaloxygen complexes (MeOn)m− in zircon.

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Abstract  

Li-, Na-, K-, Rb- and Cs-montmorillonites were saturated with benzidine, these organo-clay complexes heated under vacuum to 200°C and IR spectra recorded at various temperatures. Benzidine is mostly bound to interlayer cations through water molecules, except in Cs-clay where bonding to hydrophobic water and to water molecules which are hydrogen bonded to the oxygen plane predominates. During the thermal treatment water is lost and alkali, cations coordinate directly with benzidine. In Cs-, and to some extent also in Rb- and K-montmorillonite, benzidine is oxidized to semiquinone and quinoidal cation during the thermal treatment.

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A rapid validated thin-layer chromatography (TLC)‒densitometric method has been developed for the simultaneous determination of 3 co-formulated drugs used for common cold and cough treatment. The studied drugs are paracetamol, pseudoephedrine, and chlorpheniramine maleate. The separation was achieved using silica gel 60 F254 plates and the developing system of methanol‒ toluene‒acetic acid (44:16:1, v/v). Densitometry scanning was performed at 254 nm. The method was validated as per the International Conference on Harmonization (ICH) guidelines and was successfully applied for the analysis of pharmaceutical preparation containing the cited ternary mixture without interference from excipients. There is no previously published TLC–densitometric method for the determination of the previously mentioned ternary mixture. The suggested method is rapid and of low cost, so it can be used for quality control analysis.

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Abstract  

The solids formation behavior in a simulated high level liquid waste (HLLW) was experimentally examined, when the simulated HLLW was treated in the ordinary way of actual HLLW treatment process. Solids formation conditions and mechanism were closely discussed. The solids formation during a concentration step can be explained by considering the formation of zirconium phosphate, phosphomolybdic acid and precipitation of strontium and barium nitrates and their solubilities. For the solids formation during the denitration step, at least four courses were observed; formation of an undissolved material by a chemical reaction with each other of solute elements (zirconium, molybdenum, tellurium) precipitation by reduction (platinum group metals) formation of hydroxide or carbonate compounds (chromium, neodymium, iron nickel, strontium, barium) and a physical adsorption to stable solid such as zirconium molybdate (nickel, strontium, barium).

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Journal of Radioanalytical and Nuclear Chemistry
Authors: A. Palamalai, S. Mohan, M. Sampath, R. Srinivasan, P. Govindan, A. Chinnusamy, V. Raman, and G. Balasubramanian

Abstract  

Some batches of233U oxide product obtained from the reprocessing treatment of irradiated thorium rods, called J-rods in our plant, have been found to contain thorium as much as 85% and iron above 5% as impurities. This product has to be purified before sending for fabrication of the fuel. The present purification method consists of the following three steps: (1) preferential dissolution of U3O8 as compared to thoria, (2) a novel solvent extraction process, and (3) preferential precipitation of Th as oxalate leaving behind the entire U in the filtrate. Development and application of the present purification method to the above233U oxide proxduct are presented in this paper.

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Abstract  

A pilot plant was developed for the reclamation and reuse of secondary effluent from a sewage treatment plant. The plant system consists of sand filtration, gamma-irradiation, ozonation and ion-exchange. Gamma-irradiation showed effective organic contaminant decomposition and this resulted in the reduction of 5-day biochemical oxygen demand (BOD5), color, chemical oxygen demand (CODCr) and total organic carbon (TOC). Ion-exchange significantly removed inorganic ions, and thus reduced total nitrogen (TN) and total phosphorus (TP). The average reduction in color, CODCr, BOD5, TOC, TN and TP, which was obtained after 12 operations, was 64, 52, 67, 61, 95 and 92%, respectively. Irrespective of applied radiation dose, the treated water fully satisfied the quality requirements of household water that can be used for all home uses except for drinking and human contact uses.

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Abstract  

Five spices, cumin, coriander, clove, cinnamon and black pepper were irradiated by gamma-ray doses of 1.0 and 5.0 kGy and thermoluminescence (TL) method was used for identification of the irradiation treatment. The TL response of the minerals isolated from irradiated samples was much higher as compared to the mineral particles from unirradiated control samples. For the normalisation of results the separated minerals were reirradiated to a normalisation dose of 1.0 kGy and the TL glow curve was recorded a second time. By comparing the glow curves of irradiated and unirradiated samples, finding the ratio of the areas of first and second glow curves (TL1/TL2) and comparing the shapes of the glow curves, all the irradiated and unirradiated samples were identified correctly.

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Abstract  

The transformation mechanism of Fe cations in natural olivine after thermal treatments in air has been studied using mainly57Fe Mössbauer spectroscopy. -Fe2O3 nanoparticles appear as the primary Fe3+ phase in Mössbauer spectra of olivine samples heated at 600-900 °C. These nanoparticles are thermally unstable and they are transformed to -Fe2O3 with the increase of heating time. Another transformation mechanism of iron related with the complete decomposition of olivine structure has been observed at temperatures of 1000 °C and higher. The mixed oxide MgFe2O4 with the spinel structure and enstatite MgSiO3 were identified as iron-bearing decomposition products.

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Summary New regenerated cellulose fibers were developed during the last decades as environmentally friendly systems. In this work, three fibers: lyocell, modal and viscose were subjected to an enzymatic treatment. Likewise, different lyocell fibers were washed in a Na2CO3 solution under severe conditions. Analysis was performed by means of differential scanning calorimetry, thermogravimetry and scanning electron microscopy. In all samples, at low temperature, water desorption was detected. Furthermore, thermal analysis shows wide exothermic processes that began between 250 and 300°C corresponding to the main thermal degradation and it is associated to a depolymerization and decomposition of the regenerated cellulose. It is accompanied with mass more than 60% mass loss. Kinetic analysis was performed and activation energy values 152-202 kJ mol-1 of the main degradation process are in agreement with literature values of cellulose samples.

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