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  • Author or Editor: A. Atia x
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Abstract  

A solution of sodium silicate produced as a waste from the alkali fusion of Egyptian Rosetta zircon mineral was used for preparation of a silica gel in the pH range 6–7. A silica gel modified with tetraethylenepentamine (TEP) and diethylenetriamine (DET) functionalities were prepared. The success of immobilization process was confirmed by means of FT-IR, energy dispersive X-ray spectrometric analysis (EDX) and elemental analysis. The surface properties of the modified silica obtained were investigated by means of nitrogen surface area. The uptake behaviour of the modified silica towards Th(IV) ions at different experimental conditions of pH, time, concentration and temperature using batch method was studied. Kinetics and thermodynamics studies showed an endothermic pseudo-second order adsorption process. Regeneration of the loaded silica was performed using 1 M HNO3. The investigated silicas have successfully been applied for separating of Th(IV) from U(VI) in nitric acid solution obtained from alkaline leaching of Egyptian monazite sand.

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Interaction of salinity, nitrate, light, and seed weight on the germination of Crithmum maritimum was investigated. Seeds of three size categories were germinated at 0–200 mM NaCl with either 0, 5 or 20 mM KNO 3 . Experiments were done under darkness, white light, or red light. Regardless of seed weight, germination was maximal in distilled water. Under salinity, the smallest seeds showed the highest germination percentage. Salt impact was amplified by darkness, but was mitigated by nitrate supply, red light and their combination. At the same PPFD, germination of T2 seeds was higher, when exposed to red light than under white light, suggesting that germination was more influenced by the light type than by the PPFD. As a whole, not only salinity, nutrient availability, seed weight, and light, but also their interaction may control the germination of this halophyte.

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Abstract  

Rock samples which contain relatively high concentrations of uranium may create problems of interference produced by fission products, when instrumental neutron activation analysis is used. The isotopes95Zr,140La,141Ce, 143Ce and 147Nd, which are commonly used in the neutron activation analysis of the corresponding elements, are also produced as fission products of235U. For each of these radioisotopes, a contribution factor is calculated theoretically and meaured experimentally using geological samples with different uranium contents.

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Rapid and sensitive thin-layer chromatography (TLC) and high-performance thin-layer chromatography (HPTLC)—densitometry methods were used to separate, identify and quantify luliconazole (LUL), a new azole antifungal, in bulk and pharmaceutical dosage form. The proposed method can be used as a stability-indicating assay for the determination of LUL in the presence of its degradation products under forced degradation conditions (alkaline, acidic, oxidative, thermal and photolytic degradation). Complete separation was achieved by TLC and HPTLC on silica gel F254 plates with the solvent system toluene—isopropanol—ammonia (90:10:0.5, v/v). The chromatographic bands were visualized under short-wave ultraviolet (UV) light, and the amount of LUL was determined by scanning densitometry at 297 nm using peak area. The linear ranges were 1–24 and 0.8–6 μg band−1 with mean percentage recoveries of 99.84% ± 0.623 and 99.98% ± 1.405 for TLC and HPTLC, respectively. The methods were validated according to the International Conference on Harmonization (ICH) guidelines. The statistical analysis of the results revealed high accuracy and good precision. The suggested procedures could be used as a stability-indicating assay for the determination of LUL in drug substance and drug products in the presence of its degradation products.

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