The solid circulation rates of a binary mixture of ultrafine or superfine Al(OH)3 powders and fluidized catalytic cracking (FCC) particles were investigated in a semi‐batch circulating fluidized bed. The circulation rates were measured at different loadings of fine powders and different equilibrium water contents of the FCC particles. At a certain loading of ultrafine powders, the circulation rates were much smaller than in the presence of the superfine powders. The circulation rates were controlled by the strong cohesive property of the ultrafine powders, irrespective of the water contents of the FCC particles. Slight increases in the circulation rates were observed during fluidization of the ultrafine powders, even at higher equilibrium water contents of the FCC particles.

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Background WHO recognized the COVID-19 outbreak in China as a pandemic crisis on March 11, 2020. Patients with chronic respiratory diseases (CRDs) have limited physiological reserve; this lead to the assumption that COVID-19 infection in such patients could carry worse prognosis. Aim of study To detect the prevalence and prognostic significance of CRDs among hospitalized patients with COVID-19 infection. Methods The study was carried out at Minia Cardiothoracic University Hospital; all hospitalized COVID-19 patients during the period from January 2021 to August 2021 were included. Patients were subjected to full medical history taking, full blood count, inflammatory markers (CRP, serum ferritin, serum lactate dehydrogenase (LDH), serum D-dimer, PCR for COVID-19 infection), and HRCT chest. Need for and duration of mechanical ventilation whether invasive or non-invasive, duration of hospital stay, and condition at hospital discharge were recorded. Diagnosis for chronic respiratory disease was considered when patients have documented previous history and investigations compatible with the diagnosis, e.g., previous pulmonary function tests, chest CT, or sleep study. Results Comorbid chronic respiratory diseases were present in 57 patients (17.6%). Regarding presenting symptoms, no significant difference exists between patients with and without CRDs except for sputum production which was more frequent among patients with underlying CRDs. Elevated inflammatory markers (ferritin, D-dimer, and LDH) were more frequently observed in patients without CRDs (p < 0.0001, 0.033, and 0.008, respectively). COVID-19 with comorbid CRDs patients were more hypoxemic at presentation than other patients (p = 0.032). There was significant number of COVID-19 patients with CRDs were discharged on home oxygen therapy (p = 0.003). Regarding mortality in our cohort of patients, no significant difference exist between patients with and without CRDs (p 0.374) Among patients with comorbid CRDs, the highest mortality was observed on patients with OSA followed by ILDS and then COPD. Conclusion The presence of CRD was not found to be a poor prognostic value of COVID-19. Inflammatory markers (ferritin, D-dimer, and LDH) were significantly higher in COVID-19 patients without CRD than COVID-19 with CRD.