Neutron activation analysis for determination of metal ions in biological fluids of patients after CoCrMo arthroplasty

Determination of metals and trace elements in patients with total knee or hip arthroplasty with CoCrMo alloy was performed. Blood, urine and cerebrospinal fluid (CSF) samples were analyzed and compared with samples from healthy people. Levels of Co, Cr as well as Na, Ca, Fe, Zn, Se, Rb, Sb and Br were determined by means of neutron activation analysis. The values of Cr and Co of the blood and urine measurements were elevated in patients with replacement, and according to the statistical analysis, significant differences of the elements Zn, Br, Co and Sb were found in the CSF (p?<?0.05).

     

Investigation of HEU-type zeolite crystals after interaction with Sr2+ cations in aqueous solution using nuclear and surface analytical techniques

Pure HEU-type zeolite (heulandite) crystals were allowed to interact with Sr²⁺ cations in aqueous solution. The powdered solid experimental products obtained from batch-type sorption experiments, using solutions of Sr²⁺-concentrations between 10 and 1000 mg/l, were investigated using INAA, RI-XRF and SEM-EDS. The Sr uptake by the mineral which can adequately be described with a Freundlich-type isotherm, varies from 3.14 to 6.22 mg/g. The distribution coefficients increase progressively by decreasing the solutions concentration reaching a value of 1800 ml/g. The investigated zeolite interacts with Sr²⁺ cations through ion exchange reactions and initial exchangeable Ca²⁺ cations are replaced into the structural micropores. However, in the best case, only ca. 43% of the theoretical CEC can be covered because of the limited availability of the extra framework Ca²⁺ cations that can be removed from the lattice under ambient treatment conditions. The XPS investigation of Sr-loaded single crystals indicated that adsorption of Sr²⁺ cations on the outer surface also occurs while surface precipitation phenomena must be excluded. Similar surface analyses by means of¹²C-RBS showed that the Sr depth-distribution at near-surface layers is quite homogenous in contrast to a previous relevant study revealing an intense surface Sr-accumulation on a natural Ca-zeolite of different structural characteristics (scolecite).     

Moreau’s decomposition in Banach spaces

Moreau’s decomposition is a powerful nonlinear hilbertian analysis tool that has been used in various areas of optimization and applied mathematics. In this paper, it is extended to reflexive Banach spaces and in the context of generalized proximity measures. This extension unifies and significantly improves upon existing results.     

Weighted Uncertainty Principles in L

We determine sufficient conditions on positive weights W and V such that there exists continuous, strictly increasing functions Φ and Ψ on [0, ∞) such that Φ(0)=0=Ψ(0) and whenever f: R→R is a continuous integrable function. We also give an example that shows the optimality of our conditions.     

Uranium removal from aqueous solutions by raw and modified thermal power plant ash

The U(VI) removal from aqueous solutions (concentration range 125–2,000 mg/L, pH 3) by raw and NaOH-modified power plant ash was investigated by means of a batch method under the following experimental conditions: NaOH concentration 5 M, contact time 1 h, respectively 4 h, temperature 70, 90 °C. The amount of sorbed uranium was determined spectrophotometricaly using the Arsenazo III method. The sorbents were examined prior and after the sorption experiments by scanning electron microscopy/energy dispersive spectroscopy. Typical sorption isotherms were calculated and modeled by the Langmuir and Freundlich equations. The experimental data showed that all materials can remove considerable amounts of uranium from acidic aqueous solutions. The maximum removal efficiency (q _max) values obtained, are 126 mg U/g for raw ash and 206 mg U/g for NaOH-modified. Sorption kinetics measurements were performed at 298, 308 and 323 K and thermodynamic parameters were calculated. The kinetic data obey a pseudo-second order equation.     

Spatial and seasonal variation of radionuclides in soils and waters near a coal-fired power plant of Northern Greece: environmental dose assessment

Journal of Radioanalytical and Nuclear Chemistry - The determination of the radionuclides of U- and Th-series as well as of 40K and 137Cs in soils and waters in a lignite mining area was performed....     

Sampling in a weighted Sobolev space

We show that functions f in some weighted Sobolev space are completely determined by time-frequency samples ${\{f(t_n)\}}_{n\in \mathbb{Z}}\cup {\{\stackrel{?}{f}({\lambda }_k)\}}_{k\in \mathbb{Z}}$ along appropriate slowly increasing sequences ${\{t_n\}}_{n\in \mathbb{Z}}$ and ${\{{\lambda }_n\}}_{n\in \mathbb{Z}}$ tending to ±∞ as $n\to \pm \infty$.     

Investigation of the Cr(VI) removal from aqueous solutions by stabilized iron-nanoparticles using 51Cr-tracer

Stabilized iron-nanoparticles were used for the Cr(VI)-removal from acidic and neutral aqueous solutions (pH 1, 3, 5 and 7). The chromium interaction with the iron-nanoparticles was studied by a batch technique under different experimental conditions (e.g. pH, temperature, contact time, solid to liquid ratio) using ⁵¹Cr as radiotracer and gamma-ray spectroscopy. The results showed that the Cr-removal was fast and the interaction kinetics could be described by a pseudo-second order rate equation. The maximum Cr-removal was observed from solutions of initial pH 3. The sorption showed a positive temperature and solid to liquid ratio dependence. The experimental results were modeled using the Langmuir, Freundlich and Dubinin–Radushkevich isotherm equations and compared with literature data obtained using other sorbents. X-ray photoelectron spectroscopy (XPS) measurements were performed in order to obtain information about the mechanism of the Cr-removal by the iron-nanoparticles. It was demonstrated that the dominated process based on the Cr(VI) reduction followed by the simultaneous oxidation of iron.