Chabazite Synthesis and Its Exchange with Ti, Zn, Cu, Ag and Au for Efficient Photocatalytic Degradation of Methylene Blue Dye.

A chabazite-type zeolite was prepared by the hydrothermal method. Before ion exchange, the chabazite was activated with ammonium chloride (NH4Cl). The ion exchange process was carried out at a controlled temperature and constant stirring to obtain ion-exchanged chabazites of Ti4+ chabazite (TiCHA), Zn2+ chabazite (ZnCHA), Cu2+ chabazite (CuCHA), Ag+ chabazite (AgCHA) and Au3+ chabazite (AuCHA). Modified chabazite samples were characterized by X-ray diffraction (XRD), scanning electron microscope equipped with energy-dispersive spectroscopy (SEM-EDS), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), N2 adsorption methods and UV-visible diffuse reflectance spectroscopy (DRS). XRD results revealed that the chabazite structure did not undergo any modification during the exchange treatments. The photocatalytic activity of chabazite samples was evaluated by the degradation of methylene blue (MB) in the presence of H2O2 under ultraviolet (UV) light illumination. The photodegradation results showed a higher degradation efficiency of modified chabazites, compared to the synthesized chabazite. CuCHA showed an efficiency of 98.92% in MB degradation, with a constant of k = 0.0266 min-1 following a first-order kinetic mechanism. Then, it was demonstrated that the modified chabazites could be used for the photodegradation of dyes.

Medical Student Perceptions of the Learning Environment, Quality of Life, and the School of Medicine's Response to the COVID-19 Pandemic: A Single Institution Perspective.

PURPOSE: Responding to the COVID-19 pandemic, American medical schools made swift changes to clinical education based on guidelines provided by the Association of American Medical Colleges. The purpose of this study was to collect medical student perceptions of the solely online learning environment, their quality of life (QoL), and the pandemic response by their School of Medicine (SoM) to provide suggestions to inform medical schools' responses during the continuation of this pandemic and the next. METHODS: Between April 29, 2020 and May 16, 2020, the authors distributed a 60-item questionnaire that assessed demographics, learning environment, QoL, and the SoM response. Likert-type items were analyzed on an item-by-item basis, whereas themes were identified for open-ended questions. RESULTS: A total of 330 medical students (of 632; 52.2%) responded. Those who responded had positive perceptions of the online learning environment with moderate QoL disruptions to concentration and sleep. Although most students perceived being able to contribute meaningfully to the healthcare setting, they viewed themselves as underutilized. Three themes encapsulated both positive and negative perceptions of the SoM's response-communication, learning environment, and empathy and support. CONCLUSION: These findings provide insight into medical student perceptions of their learning environment and QoL as they acclimated to changes resulting from the COVID-19 pandemic. Results can help inform a SoM's response during the continuation of the COVID-19 pandemic as well as during future pandemics or crises. Follow-up surveys of medical students at multiple institutions across the USA and abroad will be essential to better characterize student perceptions.