The particle size dependence of the oxygen reduction reaction for carbon-supported platinum and palladium.

Model carbon supported Pt and Pd electrocatalysts have been prepared using a high-throughput physical vapor deposition method. For Pt, metal particle sizes are controlled between 1.5-5.5 nm over 100 electrodes of an electrochemical screening chip, allowing the oxygen reduction reaction (ORR) activity of the catalysts to be determined simultaneously. The ORR-specific current density is observed to increase with increasing particle diameter up to approximately 4 nm, at which point the activity begins to level off. The reduction in ORR activity for particles below 4 nm is accompanied by a concomitant increase in the overpotential for surface reduction. The resulting mass activity exhibits a maximum for particles with diameters of approximately 3.5 nm. These results are consistent with results published recently for high area carbon-supported Pt catalysts. For Pd particles, both the specific current density and the mass-specific activity for the ORR are observed to increase with increasing particle diameter, with no distinct optimum observed. The implications for the optimization of Pt- or Pd-based ORR catalysts for proton exchange membrane fuel cell (PEMFC) applications are discussed.

A multidisciplinary combinatorial approach for tuning promising hydrogen storage materials towards automotive applications.

HyStorM is a multidisciplinary hydrogen-storage project aiming to synthesise and tune materials hydrogen storage properties for automotive applications. Firstly, unique high-throughput combinatorial thin-film technologies are used to screen materials' hydrogen storage properties. Then promising thin-film candidate compositions are synthesised and examined in the bulk. In this paper, we report on our results within the ternary compositions Mg-Ti-B and Ca-Ti-B. Primary screening of the Mg-Ti-B ternary identified a high capacity hotspot corresponding to Mg0.36Ti0.06B0.58, with 10.6 wt% H2 capacity. Partial reversibility has been observed for this material in the thin-film. Bulk Ti-doped Mg(BH4)2 composites show rehydrogenation to MgH2 under the conditions used. The synthesised thin-film Ca-Ti-B ternary showed only low hydrogen storage capacities. In the bulk, Ti-doping experiments on Ca(BH4)2 demonstrated reversible storage capacities up to 5.9 wt% H2. Further characterisation experiments are required to decipher the role of the Ti-dopant in these systems in both films and in the bulk.

Labial reduction in adolescent population--a case series study.

STUDY OBJECTIVE: To find the primary referral reasons for labial reduction in adolescent girls. DESIGN: A retrospective review of six case notes of patients from July 2003 to January 2007. SETTING: Pediatric and adolescent gynecology clinic. INTERVENTIONS AND OUTCOME: Unilateral or bilateral labial reduction. The procedure was done by standard trimming of the protuberant edge of the labia minora and over-sewing the edge with 3-0 vicryl rapide. RESULTS: The age ranged from 11 to 16 years old. The reasons for requesting labial reduction were labia getting caught in underwear, being prominent under swimwear, causing vulval irritation, and its appearance causing embarrassment. All the patients were satisfied with the outcome. CONCLUSIONS: Two groups requested labial reduction. In the first group the enlarged labia caused physical discomfort. In the other group the procedure was carried out for cosmetic reasons. It is important to carefully choose the patients in the later group, because it can otherwise lead to dissatisfaction and regret later on in life. The child can give consent if Gillick competent, but it is a good practice to involve person with parental responsibility in the process of making a decision.