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Abstract
Sodium titanium germanate with a semicrystalline framework (STG) of the formula Na3H(TiO)3(GeO)(GeO4)3·7H2O was synthesized under mild hydrothermal conditions and its proton form, H4(TiO)3(GeO)(GeO4)3·8H2O (STG-H), was prepared by acid treatment of the sodium compound. The STG was characterized by elemental analysis, TGA, FT-IR, and X-ray powder diffraction. A comparative ion exchange examination of the STG-H towards alkali and alkaline earth metals in a broad pH and concentration range was carried out. It was found that the STG is a moderately weak cation exchanger, possessing high ion exchange capacity (up to 4.0 meq/g) and showing preference for heavy alkali and alkaline earth metals. The STG selectivity towards Cs+ and Sr2+ ions in the presence of competitive metal ions and certain organic compounds was also studied. The data obtained suggest that the sodium titanium germanate is a more selective exchanger for Sr2+ ion than its titanium silicate analogue, K3H(TiO)4(SiO4)3·4H2O.
Abstract
The adsorption of Ce3+ on hydrated manganese dioxide (HMD) was studied as a function of concentration, temperature and pH of the cerium solution labelled with141Ce. The steady state values of cerium adsorption at various concentrations fit well with the classical Freundlich isotherm. The effect of temperature on equilibrium adsorption values was utilized to determine the change in the standard enthalpy ΔH o of the cerium uptake process and its value (ΔH o=10.57) indicates that the uptake process proceeds via ion exchange.141Ce desorption studies, from HMD in water, HCl and unlabelled CeCl3 solution, confirmed the ion exchange nature of the cerium uptake process as well as its reversibility.
Abstract
The fractionation of different natural radionuclides (U-isotopes,226Ra and210Po) in the process used for the production of phosphoric acid in some factories located in the southwest of Spain is analyzed. As a consequence, different ways of natural radionuclide liberation to the environment can be evaluated due to these industrial activities.
Abstract
99mTc hexakis (2-methoxyisobutylisonitrile) is a cationic complex useful as a myocardial perfusion agent. The synthesis of 2-methoxyisobutylisonitrile (MIBI) by a modified and improved procedure in a two-step process with an overall yield of 53% is described. The preparation of its copper and technetium-99m complexes is also presented.
Here we present a new proof of Blatter's result: a normed space is complete if every bounded closed convex subset has an element of minimum norm. We also present geometrical conditions for the existence of minimum-norm elements in bounded closed convex sets. Also, we characterize reflexivity in the class of Banach spaces by means of contraction functions. Furthermore, we study what happens if we remove the completeness hypothesis.
We compared the haematological and biochemical values within a population of yellow-legged gulls (Larus michahellis) in the Chafarinas Islands (Northern Africa), in non-breeding (February) and breeding (May) animals. We collected blood samples from 51 adults. We found that according to the haematological data, there was a significant variation in haemoglobin content, and a higher proportion of heterophils, thrombocytes, and Haemoproteus infection in breeding individuals with a lower level in basophils. Blood biochemistry showed a higher level in plasmatic proteins, calcium, phosphorus, thiobarbituric acidreactive substances and alkaline phosphatase as well as alanine aminotransferase activity in breeding animals while cholesterol and phospholipid levels showed a lower level. There was also a sexual difference in triglycerides, albumin, thiobarbituric acid-reactive substances and alkaline phosphatase activity. Hence, the haematological and blood chemistry values of yellow-legged gulls showed some differences between breeding and non-breeding individuals as well as between sexes.
Abstract
A sufficient condition for the strict insertion of a continuous function between two comparable upper and lower semicontinuous functions on a normal space is given. Among immediate corollaries are the classical insertion theorems of Michael and Dowker. Our insertion lemma also provides purely topological proofs of some standard results on closed subsets of normal spaces which normally depend upon uniform convergence of series of continuous functions. We also establish a Tietze-type extension theorem characterizing closed G δ -sets in a normal space.
The thermal decompositions of divalent cobalt, cadmium, nickel and copper salicylates and intermediates formed during the decomposition processes were investigated by means of thermogravimetry. Two intermediates were identified in each case, except for copper(II) salicylate.
