A study was made of pneumatic transport of particles of sand suspended in air in a 31.8 mm diameter Plexiglas tube inclined at either 72 or 90 degrees with respect to the horizontal plane. The solids holdup, pressure gradient and pressure drop fluctuations over a 4.55 m test section were measured as functions of the air velocity and the solids flux. Previously observed sudden changes in slope of plots of solids holdup versus solids flux at constant gas velocity in a vertical tube (Mok et al., 1989), which were identified as transition points between dilute and dense phases, were confirmed and extended to inclined tubes. Breaks were also found in plots of pressure drop fluctuations versus solids flux at constant gas velocity.
Background Chronic cough is one of the most common symptoms in children. Postinfectious etiologies plays an important role in chronic cough in childhood. The pathogenesis of the postinfectious cough may be related persistant inflammation and the epithelial damage in the upper and lower airways, with or without transient airway hyperresponsiveness. We evaluated Mycoplasma pneumoniae and Chlamydia pneumoniae serology and treatment in children referred with chronic cough. Methods This study enrolled 41 children between 6 and 14 years of age having cough which lasted than 4 weeks. They were evaluated according to American College of Chest Physicians guideline. Pulmonary function test and chest x-ray were performed to all patients. M. pneumoniae and C. pneumoniae serologies were analayzed by ELISA. They were reevaluated with 2 to 4 weeks intervals until cough disappeared. Results The study included 41 children, 27 of whom were female (65.9%). The mean age was 8.00±1.96 year. M. pneumoniae IgM positivity was found in 17.07% (7/41) of patients, C. pneumoniae IgM positivity in 2.85% (1/35), M. pneumoniae IgM and/or IgG positivity in 41.46% (17/41), C. pneumoniae IgM and/or IgG positivity in 25.7% (9/35). Symptoms were not improved alone with clarithromycine treatment so inhaled/nasal steroids were added according to diagnosis. Conclusion In children with chronic chough, aged 6 to 14 years old, M. pneumoniae and C. pneumoniae play important roles in the etiology. Clarithromycine alone may not be enough in the treatment of chronic cough due to these agents, so the treatment should be planned according to clinical findings.
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