38 research outputs found

    A structural magnetic resonance imaging study in therapy-naĂŻve transsexual individuals

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    Background: Transsexuality is explained and defined as a gender-identity disorder, characterised by very strong conviction of belonging to the opposite sex and has been associated with a distinct neuroanatomical pattern. Materials and methods: We performed a structural analysis in search of possible differences in grey matter structures based on magnetic resonance imaging scans of the brains of 26 individuals between 19 and 38 years of age. The participants were divided into two groups of 15 controls and 11 transgender individuals. The segmentation of subcortical grey matter was performed using FIRST model a model-based segmentation/registration tool, from FSL software package. Results: The results showed that the volume of the brain region called nucleus accumbens on the left side was significantly smaller in the group of transgender individuals compared to the control. It was the most important parameter which was shown to make distinction between two examined groups. Conclusions: The results also showed decreased volumes of the left thalamus, right hippocampus and right caudate nucleus

    Analysis of Be-7 behaviour in the air by using a multilayer perceptron neural network

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    A multilayer perceptron artificial neural network (ANN) model for the prediction of the Be-7 behaviour in the air as the function of meteorological parameters was developed. The model was optimized and tested using Be-7 activity concentrations obtained by standard gamma-ray spectrometric analysis of air samples collected in Belgrade (Serbia) during 2009-2011 and meteorological data for the same period. Good correlation (r = 0.91) between experimental values of Be-7 activity concentrations and those predicted by ANN was obtained. The good performance of the model in prediction of Be-7 activity concentrations could provide basis for construction of models which would forecast behaviour of other airborne radionuclides. (C) 2014 Elsevier Ltd. All rights reserved

    Removal of lead from aqueous solutions by using the natural and Fe(III)-modified zeolite

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    In the present study, the sorption of lead by the natural and Fe(III)-modified zeolite (clinoptilolite) is described. The characterization of the natural zeolite-rich rock and the Fe(III)-modified form was performed by chemical analysis, point of the zero charge (pHpzc), X-ray powder diffraction, applying the Rietveld/RIR method for the quantitative phase analysis, and scanning electron microscopy. The effects of sorbents dose and the initial lead concentrations on its sorption by two sorbents were investigated. For both sorbents, it was determined that at lower initial concentrations of lead, ion exchange of inorganic cations in zeolites with lead, together with uptake of hydrogen dominated, while at higher initial lead concentrations beside these processes, chemisorption of lead occurred. Significantly higher sorption of lead was achieved with Fe(III)-modified zeolite. From sorption isotherms, maximum sorbed amounts of lead, under the applied experimental conditions, were 66 mg/g for the natural and 133 mg/g for Fe(III)modified zeolite. The best fit of experimental data was achieved with the Freundlich model (R-2 >= 0.94)

    Adsorption of mycotoxins by organozeolites

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    Adsorption of zearalenone (ZEN), ochratoxin A (OCHRA) and aflatoxin B1 (AFB1) on natural zeolite, clinoptilolite, modified with different amounts of octadecyldimethylbenzyl ammonium (ODMBA) ions was investigated. Results showed that adsorption of hydrophobic ionizable ZEN on unmodified zeolite tuff was very low and that adsorption on organozeolites increased with increasing hydrophobicity of the zeolitic surface. The adsorption was independent of the form of ZEN in solution and the solution pH, indicating that hydrophobic interactions with ODMBA are responsible for ZEN adsorption. Adsorption of low polar ionizable OCHRA on organozeolites also increased with increasing hydrophobicity of the zeolitic surface, however, OCHRA showed moderate adsorption on unmodified zeolitic tuff at pH 3. OCHRA adsorption on unmodified zeolite as well as on lower surface coverage of organozeolite was dependent on the form of OCHRA in solution; there was a decrease of adsorption at high pH, where OCHRA is in the anionic form. It indicated that at acidic pH, low surface coverage allows some combination of hydrophobic interaction with ODMBA and interactions with the surface of the zeolite. At higher surface coverage, the OCHRA adsorption was higher and practically independent of pH, indicating that the hydrophobic interactions of OCHRA with ODMBA are responsible for its adsorption. Nonionizable low polar AFB1 had a high affinity for the unmodified zeolitic tuff and the adsorption of AFB1 was greatly reduced for organozeolites, indicating that AFB1 does not have high tendency for hydrophobic interactions with ODMBA. pH dependence of AFB1 adsorption, while AFB1 has the same form at all pHs, demonstrated that the surface modification of the zeolite depends on pH and that these modifications have influence on its adsorption. The calculated dipole moments of neutral mycotoxin molecules: AFB1-9.5D, OCHRA-6.9D and ZEN-2.2D are in qualitative agreement with adsorption experimental data. (c) 2005 Elsevier B.V All rights reserved

    Application of surfactant modified natural zeolites for the removal of salicylic acid—a contaminant of emerging concern

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    This work aimed to test composites (surfactant modified zeolites prepared by treatment of natural zeolites—clinoptilolite (IZ CLI) and/or phillipsite (PHIL75)-rich tuffs with two different amounts of cationic surfactants: cetylpyridinium chloride (CPyCl) and Arquad® 2HT-75 (ARQ)) for the adsorption of salicylic acid (SA)—a common contaminant of emerging concern. Adsorption of SA was studied at different initial drug concentrations (in the range of 2–100 mg/L) in water solution. The Langmuir isotherm model showed the highest adsorption was achieved by bilayer composite of IZ CLI and CPyCl—around 11 mg/g. Kinetic runs were performed by using the initial drug concentration of 20 mg/L in the time interval from 0 to 75 min and pseudo-second order had good correlation with experimental data. The influence of the four different temperatures on the SA adsorption was also investigated and thermodynamic parameters suggested that the adsorption drug onto composites is an exothermic and nonspontaneous process, followed by the decrease of randomness at the solid/liquid interface during the adsorption. Zeta potential and Fourier-transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) had been performed for the characterization of composites after adsorption of SA confirming the presence of the drug at composite surfaces

    Solid targetry at the TESLA Accelerator Installation

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    According to the concept of the TESLA Accelerator Installation, the channel for production of radioisotopes has to routinely produce Tl-201, In-111, Ga-67, I-123 and F-18, and a number of other radionuclides for experimental purposes. The production of I-123 and F-18 will be performed in dedicated, commercial target stations, while a versatile solid target irradiation system is designed for the routine and experimental production of all other radioisotopes. The solid target station is designed to accept targets for both the 7degrees and 90degrees irradiation geometry. The targets used for the routine production will be prepared by electroplating on a silver substrate. They can be irradiated with a 1.5 kW beam using the 7degrees geometry. The cooling of these targets is enhanced by fins on the back of the silver substrate designed so that the highest temperature on the surface of the target does not exceed 110degreesC. The irradiation procedures will conform to the GMP requirements for the production of radio pharmaceuticals. The irradiated targets will be transported directly into the appropriate hot cell for radiochemical processing, All cells will be equipped with a target dissolution unit for etching the irradiated, electroplated film. After decontamination and sufficient cooling down, these targets will be reused several times. (C) 2001 Elsevier Science B.V. All rights reserved.20th World Conferenceof the International-Nuclear-Target-Development-Society (INTDS), Oct 02-06, 2000, Antwerp, Belgiu

    Removal of emerging contaminants from water by zeolite-rich composites: A first approach aiming at diclofenac and ketoprofen

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    In this study, composites of the natural zeolites and cationic surfactants cetylpyridinium chloride and Arquad® 2HT-75 were used for removal of two emerging contaminants – diclofenac sodium and ketoprofen. Modifying a clinoptilolite- and a phillipsite-rich tuff, with surfactants with one or two hydrophobic tails, resulted in composites in monolayer and bilayer forms. The intention was to better evaluate interactions of composites with selected molecules. Starting materials and composites were characterized by ATR–FTIR and STA coupled with EGA. The adsorption capacities of the prepared sorbents were estimated by determination of adsorption isotherms and kinetic runs. Maximum adsorption capacity, obtained from the Langmuir model, showed that the best results were for the bilayer form of the composites up to 35 mg/g. Between the two surfactants, composites with cetylpyridinium chloride gave better results. Zeta potential measurements showed that the surfactants turned out to be unstable on the zeolite surface, the only exception being bilayers prepared using the two-tailed surfactant Arquad® 2HT-75. These results suggested possible applications of these composites for water treatment purposes

    Surface modified natural zeolites (SMNZs) as nanocomposite versatile materials for health and environment

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    The present research deals with the evaluation of a clinoptilolite-rich rock, occurring in the Nižný Hrabovec deposit (Slovakia), for high-value technological applications based on sorption and in vitro release of nonsteroidal anti-inflammatory drugs (i.e., ibuprofen sodium salt). This georesource was surface modified (SMNZ) using four cationic surfactants. Results demonstrate that ibuprofen sorption is very fast and SMZNs can sorb up to ˜26 mg/g of drug as a function of the type of counterion and morphology of surfactant, as well as the hydrophobicity and molecular structure of the drug. Maximum sorption capacities observed for all SMNZs are fully comparable to other adsorbent carriers usually used for removal of contaminants in wastewaters. Sorption of ibuprofen is controlled by a dual mechanism: external anionic exchange and partition into the hydrophobic portion of the patchy bilayer. A prompt drug release in simulated intestinal fluid (SIF) was also observed, making this natural material also suitable to provide rapid soothing effects in potential pharmacological applications. Comparing the results of this study with other recent investigations, a good technological performance of clinoptilolite-rich rock can be inferred despite the relatively low zeolite content (˜56 wt.%)
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