54 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

    Zearalenone and ochratoxin A: adsorption by kaolin modified with surfactant

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    Octadecyldimethylbenzyl ammonium chloride (OA) was used as a surfactant for the preparation of organokaolin. The natural kaolin (from a plant for production of quartz sand in Rgotina, Serbia) was modiïŹed with a surfactant in amount equal to 90% of the kaolin cation exchange capacity (CEC). FTIR spectroscopy was used for characterization of the new product. FTIR spectra confirmed the presence of OA ions at the kaolin surface. Adsorption of mycotoxins – zearalenone (ZEN) and ochratoxin A (OCHRA) was studied by organokaolin at different amounts of adsorbent and pHs. Results showed that the presence of organic cations in the kaolin structure increased adsorption of both ZEN and OCHRA. Adsorption of the mycotoxins by organokaolin increased with increasing amounts of adsorbent and, at the lowest amount of solids in suspension, adsorption of ZEN and OCHRA was slightly higher at pH 7 and 9

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    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 Arquad¼ 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

    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 Arquad¼ 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 Arquad¼ 2HT-75. These results suggested possible applications of these composites for water treatment purposes

    Reduction in lesions from Lmax: a new concept for assessing efficacy of field-directed therapy for actinic keratosis. Results with imiquimod 3.75%

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    Background: Current parameters for assessing the efficacy of actinic keratosis (AK) treatments compare clinical lesions at the start and end of a study. However, the sun-exposed field also contains subclinical lesions which may become detectable during treatment. Lmax, the maximum lesion count during treatment, is a new concept to better assess the efficacy of field-directed AK therapies. Measuring efficacy using the reduction in lesions from Lmax includes for the first time the clearance of both subclinical and clinical lesions. Objectives: To evaluate the reduction of lesions from Lmax to study end and compare the results with traditional efficacy endpoints using imiquimod 3.75% (IQ3.75%) as an example of field-directed AK therapy. Materials & Methods: Pooled analysis of data from two 14-week, vehicle-controlled, double-blind studies of IQ3.75%. Results: With IQ3.75%, the median number of lesions increased from 10 at baseline to an Lmax of 22. The median absolute reduction in lesions to study end was 18 from Lmax versus 7 from baseline. The median percentage reduction in AK lesions to study end was 92.2% from Lmax compared with 81.8% from baseline. Conclusions: The reduction in lesion count from Lmax is a novel efficacy parameter that should become the new way of evaluating field-directed AK therapies since it enables their efficacy against both clinical and subclinical lesions to be accurately determined. Together, the Lmax concept and IQ3.75% represent a new approach for the management of AK across a large sun-exposed field
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