Phototransformation of ibuprofen and ketoprofen in aqueous solutions.

The UV (254 nm) and UV/VUV (254/185 nm) photolysis of two anti-inflammatory drugs, ibuprofen and ketoprofen, have been studied in aqueous solutions as a possible process for the removal of non-biodegradable compounds. We have examined the effects of dissolved oxygen and initial target concentration. Upon irradiation at 254 nm, the decomposition rate of ketoprofen is almost forty times higher as it of ibuprofen whilst VUV irradiation only increased the ibuprofen decomposition rate. The presence of dissolved oxygen accelerated the photodegradation of ibuprofen, whereas no effect was observed on the degradation of ketoprofen. The maximum quantum yield for the phototransformation was 0.2. The rate of mineralization in both cases was ∼60%, even after 1h of treatment and this suggests the formation of stable by-products which were identified using GC-MS and HPLC-MS, respectively.

Social cognition and Theory of Mind in patients with relapsing-remitting multiple sclerosis.

BACKGROUND: Theory of Mind (ToM) is an ability to understand and interpret another person's beliefs, emotions, and intentions. ToM requires both cognitive and emotional perspective taking and is deficient in several neuropsychiatric disorders all connected with impaired social functioning. Cognitive and mood dysfunctions have been recognized as common symptoms in multiple sclerosis (MS). METHODS: We investigated social cognition in 40 ambulatory patients with MS compared to 35 healthy controls by using verbal and non-verbal ToM tests (Faux Pas, Baron-Cohen's Adult Eyes and Faces test) and Baron-Cohen's Empathy questionnaire. The effect of disability and disease duration on social cognition was also analyzed by multiple logistic regression analysis after adjusting for confounding factors of age, gender, intelligence, depression, and anxiety. RESULTS: Even when adjusted, patients with MS made significantly more mistakes in non-verbal test (adult Eyes Test), and more disabled patients performed worse in both verbal and non-verbal ToM tests (Eyes Test and Faux Pas) compared to controls. Patients with a shorter disease course described themselves as more empathetic. DISCUSSION: In the absence of marked cognitive decline and disability, patients with ambulatory MS had a deficit interpreting social situations and performing in interpersonal contexts.

Surfactant double layer stabilized magnetic nanofluids for biomedical application.

Magnetite nanoparticles were coated with surfactant double layers in order to prepare water based magnetic fluids (MFs). The effects of head group (sulfonate, carboxylate) and alkyl chain length (11-17 C atoms) and the combination of surfactants were studied. Adsorption, dynamic light scattering (DLS) and electrophoretic mobility measurements were performed. The quantity of surfactant varied between 0.3 and 0.5 g, i.e. their specific amount ranges over 1.5-2 mmol g(-1) magnetite in MFs. The adsorption isotherm of Na oleate on magnetite proved the double layer formation with 2 mmol g(-1) saturation value in good harmony with the empirical doses. The effect of diluting MFs, pH and salt concentration was studied. The pH-dependent stability and the salt tolerance of MFs were different owing to the dissociation of the outermost hydrophilic groups and the hydrophobic interactions scaling with the alkyl chain length of surfactant. The hydrophobic interactions are favored only for oleic and myristic acid double layers. In these MFs, aggregation cannot be observed even in fairly dilute systems up to the physiological salt concentration around neutral pH 6-8 favored in biomedical application. The stable oleic and myristic acid double layers can hinder effectively the aggregation of magnetite particles due to the combined steric and electrostatic stabilization.

The effect of humic acid adsorption on pH-dependent surface charging and aggregation of magnetite nanoparticles.

The pH-dependent adsorption of humic acid (HA) on magnetite and its effect on the surface charging and the aggregation of oxide particles were investigated. HA was extracted from brown coal. Synthetic magnetite was prepared by alkaline hydrolysis of iron(II) and iron(III) salts. The pH-dependent particle charge and aggregation, and coagulation kinetics at pH approximately 4 were measured by laser Doppler electrophoresis and dynamic light scattering. The charge of pure magnetite reverses from positive to negative at pH approximately 8, which may consider as isoelectric point (IEP). Near this pH, large aggregates form, while stable sols exist further from it. In the presence of increasing HA loading, the IEP shifts to lower pH, then at higher loading, magnetite becomes negatively charged even at low pHs, which indicate the neutralization and gradual recharging positive charges on surface. In acidic region, the trace HA amounts are adsorbed on magnetite surface as oppositely charged patches, systems become highly unstable due to heterocoagulation. Above the adsorption saturation, however, the nanoparticles are stabilized in a way of combined steric and electrostatic effects. The HA coated magnetite particles form stable colloidal dispersion, particle aggregation does not occur in a wide range of pH and salt tolerance is enhanced.