Photocatalytic hydrogen production by water/methanol decomposition using Au/TiO2 prepared by deposition-precipitation with urea.

Gold nanoparticles deposited on TiO2 Degussa P25, prepared by deposition-precipitation with urea, were studied in the photocatalytic hydrogen production. The effect of parameters such as mass of catalyst, gold loading, thermal treatment, and atmosphere of treatment was evaluated and optimized. The presence of metallic gold on the titania surface showed to have contributed to the high improvement in the activity of bare TiO2 for hydrogen generation under UV light (λ=254 nm) using a lamp of low energy (2W) consumption. The optimal gold loading for the photocatalysts was 0.5 wt.%, the mass of catalyst in the reactor was 0.5 g/L in a water/methanol 1:1 vol. solution, and the thermal treatment that produced the most active gold nanoparticles was found at 300°C. The photocatalysts thermally treated under hydrogen at 300°C produced 1492 µmol g(-1)h(-1) of hydrogen; the same catalyst activated in air produced 1866 µmo lg(-1)h(-1) of hydrogen.

[The neuropsychological phenotype of attention deficit hyperactivity disorder: are there differences among subtypes?]. / Fenotipo neuropsicológico del trastorno de déficit atencional/hiperactividad: existen diferencias entre los subtipos?

INTRODUCTION: Recent studies suggest that the ADHD subtypes would be best conceptualized as separate clinical entities, based on their epidemiology, central and associate symptomatology. OBJECTIVES: To determine the differences and similarities between subtypes in its associate symptomatology, specifically in the neuropsychological phenotype of executive dysfunction. PATIENTS AND METHODS: A group of children between 6 and 14 years of age with a diagnosis of ADHD-innattentive subtype (DESAT, n = 20) and another with ADHD-combined subtype (COMB, n = 39). RESULTS: Overall, the COMB subject sample displayed lower performance than DESAT group. Statistically significant differences were found in Kaufman-ABC-hands movement subtest, Wisconsin Card Sorting Test (WCST)-total error and WCST-conceptual level. CONCLUSIONS: The subtypes differ significantly in measures or non verbal working memory, hindsight, foresight, and motor control. Both groups share a deficit in response output speed and verbal working memory. We hypothesized areas of cognitive superiority for each subtype: spatial memory for the inattentive and gestaltic composition for the combined. Results provide evidence to support quantitative and qualitative differences in the neuropsychological profile between the ADHD-innatentive and combined subtypes.