Synthesis and Characterization of Cobalt and Nitrogen Co Doped Peat Derived Carbon Catalysts for Oxygen Reduction in Acidic Media

In this study, several peat derived carbons PDC were synthesized using various carbonization protocols. It was found that depending on the carbonization method, carbons with very different surface morphologies, elemental compositions, porosities, and oxygen reduction reaction ORR activities were obtained. Five carbons were used as carbon supports to synthesize Co N PDC catalysts, and five different ORR catalysts were acquired. The surface analysis revealed that a higher nitrogen content, number of surface oxide defects, and higher specific surface area lead to higher ORR activity of the Co N PDC catalysts in acidic solution. The catalyst Co N C 2 ZnCl2 , which was synthesized from ZnCl2 activated and pyrolyzed peat, showed the highest ORR activity in both rotating disk electrode and polymer electrolyte membrane fuel cell tests. A maximum power density value of 210 mW cm2 has been obtained. The results of this study indicate that PDCs are promising candidates for the synthesis of active non platinum group metal type catalyst

Ionic liquids at electrified interfaces

Until recently, “room-temperature” (<100–150 °C) liquid-state electrochemistry was mostly electrochemistry of diluted electrolytes(1)–(4) where dissolved salt ions were surrounded by a considerable amount of solvent molecules. Highly concentrated liquid electrolytes were mostly considered in the narrow (albeit important) niche of high-temperature electrochemistry of molten inorganic salts(5-9) and in the even narrower niche of “first-generation” room temperature ionic liquids, RTILs (such as chloro-aluminates and alkylammonium nitrates).(10-14) The situation has changed dramatically in the 2000s after the discovery of new moisture- and temperature-stable RTILs.(15, 16) These days, the “later generation” RTILs attracted wide attention within the electrochemical community.(17-31) Indeed, RTILs, as a class of compounds, possess a unique combination of properties (high charge density, electrochemical stability, low/negligible volatility, tunable polarity, etc.) that make them very attractive substances from fundamental and application points of view.(32-38) Most importantly, they can mix with each other in “cocktails” of one’s choice to acquire the desired properties (e.g., wider temperature range of the liquid phase(39, 40)) and can serve as almost “universal” solvents.(37, 41, 42) It is worth noting here one of the advantages of RTILs as compared to their high-temperature molten salt (HTMS)(43) “sister-systems”.(44) In RTILs the dissolved molecules are not imbedded in a harsh high temperature environment which could be destructive for many classes of fragile (organic) molecules

A compact and cost-effective hard X-ray free-electron laser driven by a high-brightness and low-energy electron beam

We present the first lasing results of SwissFEL, a hard X-ray free-electron laser (FEL) that recently came into operation at the Paul Scherrer Institute in Switzerland. SwissFEL is a very stable, compact and cost-effective X-ray FEL facility driven by a low-energy and ultra-low-emittance electron beam travelling through short-period undulators. It delivers stable hard X-ray FEL radiation at 1-Å wavelength with pulse energies of more than 500 μJ, pulse durations of ~30 fs (root mean square) and spectral bandwidth below the per-mil level. Using special configurations, we have produced pulses shorter than 1 fs and, in a different set-up, broadband radiation with an unprecedented bandwidth of ~2%. The extremely small emittance demonstrated at SwissFEL paves the way for even more compact and affordable hard X-ray FELs, potentially boosting the number of facilities worldwide and thereby expanding the population of the scientific community that has access to X-ray FEL radiation

Dosimetric evaluation and comparison of different RF exposure apparatuses used in human volunteer studies

The aim of this study was to provide the information necessary to enable the comparison of exposure conditions in different human volunteer studies published by the research groups at the Universities of Turku, Swinburne, and Zurich. The latter applied a setup optimized for human volunteer studies in the context of risk assessment while the first two applied a modified commercial mobile phone for which detailed dosimetric data were lacking. While the Zurich Setup exposed the entire cortex of the target hemisphere, the other two setups resulted in only very localized exposure of the upper cheek, and concentrated on a limited area of the middle temporal gyrus just above the ear. The resulting peak spatial SAR averaged over 1 g of the cortex was 0.19 W/kg of the Swinburne Setup, and 0.31 W/kg for the Turku Setup, compared to 1 W/kg for the Zurich Setup. The average exposure of the thalamus was 5% and 9% of the Zurich Setup results for the Swinburne and Turku Setups, respectively. In general, the phone-based setup results in only reasonably defined exposures in a very limited area around the maximum exposure; the exposure of the rest of the cortex was low, and may vary greatly as a function of the setup, position, and local anatomy. The analysis confirms the need for a carefully designed exposure setup that exposes the relevant brain areas to a well-defined level in human volunteer studies, and shows that studies can only be properly compared and replicated if sufficiently detailed dosimetric information is available

Surface enhanced Raman spectroscopy of organic molecules deposited on gold sputtered substrates

International audienc

The shifting sands of time : maturation and athlete development

In the first two decades of life, notably the years associated with childhood and adolescence, the human body grows and changes substantially. Physical growth is considered a continuous process with a predictable sequence of changes occurring until full adult maturity at approximately 18–20 years of age for males, and 16–18 years for females. The most observable changes are associated with physical (somatic) body proportions (e.g., height and body mass), although growth encompasses multiple other components, including bone, nerve, and neural network, as well as muscle and fat tissue development (Malina, Bouchard, & Bar-Or, 2004). Considering such changes, this chapter focuses on: (i) highlighting the potential for growth and maturational variability between individuals at similar chronological ages; (ii) outlining the relationships between physical maturation and facets of athletic performance; (iii) providing a conceptual model to demonstrate normative growth and maturational related change over time; and (iv) noting the resultant systematic biases in athlete participation, evaluation and selection. In a final section, maturation measurement methods and issues are discussed. These topics are addressed to help establish a clear message – that sports organisations and practitioners need to better understand and account for variability in growth and maturation within their sport systems and athlete development programs

Defined adhesion and growth of neurones on artificial structured substrates

Patterned adhesion of neurones and directed growth of neurites is the pre-requisite to establish meaningful in vitro models for the study of interactions and signalling between neurones. We have therefore studied two model systems for structured substrates. Silicon samples were microstructured by etching. Neurones adhered preferentially onto the bottom of the resulting grooves and wells. Outgrowth of neurites could be observed on adsorptive coating with polylysine and laminin. Most of the neurites did not cross the border between the plain surfaces of the silicon sample and the bottom of the grooves and wells. The second approach was to use interdigitating platinum comb electrodes. One of them was coated with laminin by electrochemical polymerisation. A strong outgrowth of axons was found, and such a surface modification appears to be suitable for the creation of neuronal patterns with effective growth of axons in vitro. (C) 2001 Elsevier Science Ltd. All rights reserved

Effect of a general school-based physical activity intervention on bone mineral content and density: A cluster-randomized controlled trial

BACKGROUND: Specific physical loading leads to enhanced bone development during childhood. A general physical activity program mimicking a real-life situation was successful at increasing general physical health in children. Yet, it is not clear whether it can equally increase bone mineral mass. We performed a cluster-randomized controlled trial in children of both gender and different pubertal stages to determine whether a school-based physical activity (PA) program during one school-year influences bone mineral content (BMC) and density (BMD), irrespective of gender. METHODS: Twenty-eight 1st and 5th grade (6-7 and 11-12year-old) classes were cluster randomized to an intervention (INT, 16 classes, n=297) and control (CON; 12 classes, n=205) group. The intervention consisted of a multi-component PA intervention including daily physical education with at least 10min of jumping or strength training exercises of various intensities. Measurements included anthropometry, and BMC and BMD of total body, femoral neck, total hip and lumbar spine using dual-energy X-ray absorptiometry (DXA). PA was assessed by accelerometers and Tanner stages by questionnaires. Analyses were performed by a regression model adjusted for gender, baseline height and weight, baseline PA, post-intervention pubertal stage, baseline BMC, and cluster. RESULTS: 275 (72%) of 380 children who initially agreed to have DXA measurements had also post-intervention DXA and PA data. Mean age of prepubertal and pubertal children at baseline was 8.7±2.1 and 11.1±0.6years, respectively. Compared to CON, children in INT showed statistically significant increases in BMC of total body, femoral neck, and lumbar spine by 5.5%, 5.4% and 4.7% (all p<0.05), respectively, and BMD of total body and lumbar spine by 8.4% and 7.3% (both p<0.01), respectively. There was no gender⁎group, but a pubertal stage⁎group interaction consistently favoring prepubertal children. CONCLUSION: A general school-based PA intervention can increase bone health in elementary school children of both genders, particularly before puberty