70 research outputs found

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

    Get PDF
    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

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

    Get PDF
    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 ÎŒJ, 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

    Ionic liquids at electrified interfaces

    Get PDF
    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

    Presentations with reported methamphetamine use to an urban emergency department in Switzerland.

    Get PDF
    AIMS OF THE STUDY The stimulant methamphetamine (e.g., "crystal meth") is a commonly abused drug in many parts of the world and can cause significant health problems. The present study aims to describe presentations with reported methamphetamine use at an urban emergency department (ED) in Switzerland, to investigate prevalence, patterns and susceptible groups. METHODS Retrospective study at the ED of the University Hospital of Bern, Switzerland. Cases from June 2012 to July 2019 were retrieved from the electronic patient database using full-text terms and were categorised into three groups based on patient history: "acute", if patients presented within 72 hours of last reported use, "chronic" in cases of regular use but not within the previous 72 hours, and "past" in cases of discontinued consumption. Cases with a positive methamphetamine urine drug screening test with no further information available were described separately. RESULTS During the study period, 40 cases were categorised as "acute". Among those, the mean age was 29.5 years (standard deviation [SD] 8.7), 75% (n = 30) were male, and agitation (n = 11, 28%), hypertension (n = 11, 28%), tachycardia (n = 11, 28%), sleep disturbances (n = 10, 25%) and aggression (n = 8, 20%) were the most common symptoms. Most patients (n = 22, 55%) were medically discharged, but 35% (n = 14) were admitted to a psychiatric clinic. Most (n = 33, 82.5%) were polydrug users, with alcohol, cocaine and cannabis being the most frequent co-used substances. The "chronic" group included 37 cases. Those patients were mostly male (n = 26, 70%), with a mean age of 31 years (SD 11.0), and 46% (n = 17) presented because of psychiatric symptoms, such as psychosis, depression or aggression. Of the 45 cases in the "past" group (mean age of 30 years, SD 8.6), 69% (n = 31) were male, and 49% (n = 22) and 24% (n = 11), respectively, had medical and psychiatric symptoms as the reason for admission. Of 61 cases with a positive urine drug screening test as the sole indicator of methamphetamine use, 19 patients reported MDMA use (cross-reactivity with methamphetamine in the urine immunoassay used). In the 42 remaining cases, it was unclear if the positive result was due to unreported methamphetamine use or cross-reactivity. CONCLUSIONS Most patients with reported methamphetamine use were young and male, with signs of sympathomimetic arousal and/or psychiatric symptoms. Although ED visits with reports of methamphetamine use appear to be uncommon, consumption-related health problems can require significant pre- and in-hospital resources
    • 

    corecore