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Omar A. Hazzazi Gary A. Attard Peter B. Wells F.J. Vidal-Iglesias Meritxell Casadesus 《Journal of electroanalytical chemistry (Lausanne, Switzerland)》2009,625(2):123-130
The cyclic voltammetric (CV) behaviour of gold adsorbed on Pt{h k l} electrodes is reported. It is found that stepped surfaces vicinal to Pt{1 1 1} exhibit preferential adsorption of gold at step sites. However, for stepped surfaces containing Pt{1 0 0} terraces, adsorption of gold at step and terrace site occurs with equal probability, although for Pt{n 1 1} electrodes with n < 7 (i.e. electrodes containing short Pt{1 0 0} terraces), slight preference for step site adsorption is still observed. This behaviour is similar to that reported previously for Bi adsorption on Pt{h k l} and is interpreted in terms of slower rates of gold atom surface diffusion across Pt{1 0 0} vs. Pt{1 1 1} terraces. By comparing the electrochemical response of gold adlayers on Pt{h k l} with previously published bulk Au{h k l} voltammetry, it is deduced that the gold overlayers on Pt{h k l} are pseudomorphic in nature. This finding is in agreement with previous UHV and electrochemical results for gold deposition on platinum. Using such gold modified Pt{h k l} electrodes as model surfaces, we also report, for the first time, the electrooxidation of ethanol on Au/Pt{h k l} in alkaline aqueous solution. The ethanol oxidation reaction (EOR) is shown to be structure sensitive for submonolayer gold coverages. In fact, a maximum in the rate of EOR at platinum sites adjacent to gold islands is observed between approximately 0.4–0.6 monolayers of gold on Pt{1 0 0}, Pt{1 1 1} and Pt{1 1 0} in 0.1 M NaOH(aq). A second electrooxidation state at more positive potentials for 0 < θAu < 1 ascribed to EOR at pure gold sites is also observed, at least for Pt{1 1 1} and Pt{1 0 0}. On Pt{1 1 1}, the potential range and activity of EOR in this second process is similar to bulk gold whereas for submonolayer gold films on Pt{1 0 0}, the peak is shifted to more negative potentials. 相似文献
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Ismail A. Walbi Hassan A. Albarqi Nayef Saleh Alghanim Marzooq Abdullah Albadi Hesham Mohammed Al Maimouni Saad Ahmed Alkahtani Ali Mohamed Alshabi Amer S. Alali Faleh Alqahtani Amal Hassan Al-Najjar Mohammad A Hazzazi Deemah S Alanazi Abdulrahman Abdulaziz Sabei Omer S Alsaweed Rahaf K Alajra Hussain Alqhtani 《The Journal of international medical research》2022,50(4)
ObjectiveHydroxychloroquine (HCQ) has been used during the coronavirus disease 2019 (COVID-19) pandemic because of its reported anti-viral activity. This study examined the association of chronic HCQ use with the incidence and complications of COVID-19.MethodsThis retrospective cohort study included adults with rheumatoid arthritis and/or systemic lupus erythematosus who visited rheumatology clinics in three tertiary hospitals in Riyadh, Saudi Arabia between January 2019 and December 2020. Patients were categorized into two groups based on HCQ use. Data were obtained from the electronic health record and by interviews with patients. The primary study objective was the incidence of COVID-19 and its complications from March 2020 to February 2021.ResultsAlmost 11% of the study cohort was positive for COVID-19, and the incidence of COVID-19 was similar between HCQ users (11.11%) and nonusers (10.86%). Disease complication rates were similar in the study arms, and they mainly included fever, dry cough, fatigue, and breathing difficulty.ConclusionsThis study revealed no significant association between chronic HCQ use and the incidence of COVID-19, and disease complications were similar in the study arms. 相似文献
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