Reverse airflow

Naturally, there is no reverse airflow on an induced-draft fan. That can occur only in a forced-draft fan. Reverse airflow can be observed with a forced-draft fan, by seeing which portions of the screen, shown in Fig. 14,2, will not allow a dollar bill to stick to the underside of the... 

Asthma is a respiratory illness characterized by variable and reversible airflow obstruction. Over 100 years ago. Osier, in his influential Textbook of Medicine (Osier, 1892), concluded that airway wall edema, bronchoconstriaion and mucus plugging are responsible for the airflow obstruction in asthma. Since that time, edema of the airway mucosa has been assumed to be one of the central features of asthma, but comparatively few studies have addressed the issue directly. Therefore, there is litde information about the onset, duration, magnitude, location, mechanism, consequences and management of mucosal edema in asthma. 

Performance data for direct heat tray dryers A standard two-truck dryer is illustrated in Fig. 12-44. Adjustable baffles or a perforated distribution plate is normally employed to develop 0.3 to 1.3 cm of water pressure drop at the wall through which air enters the truck enclosure. This will enhance the uniformity of air distribution, from top to bottom, among the trays. In three (or more) truck ovens, air reheat coils may be placed between trucks if the evaporative load is high. Means for reversing airflow direction may also be provided in multiple-truck units. 

Asthma is a mostly reversible, chronic airway inflammatory disease associated with airflow obstruction, bronchial hyperresponsiveness (BHR), and airway inflammation. Clinical symptoms are cough, wheezing, shortness of breath, and chest tightness caused by mostly reversible airflow obstruction. Inflammation is a key component of asthma. 

Melchor R, Biddiscombe M, Mak V, Short M, Spiro S. Lung deposition patterns of directly labelled salbutamol in normal subjects and in patients with reversible airflow obstruction. Thorax 1993 48 506-511. 

Bollert EG, Matusiewicz SP, Dewar MH, Brown GM, McLean A, Greening AP. Comparative efficacy and potency of ipratropium via Turbuhaler and pressurized metered-dose inhaler in reversible airflow obstruction. Eur Respir J 1997 10 1824-1828. 

Yates B, Murphy DM, Forrest lA, et al. Azithromycin reverses airflow obstruction in established bronchiolitis obliterans syndrome. Am J Respir Grit Care Med 2005 172(6) 772-775. 

Taveira-DaSilva AM, Hedin C, Stylianou MP, et al. Reversible airflow obstruction, proliferation of abnormal smooth muscle cells, and impairment of gas exchange as predictors of outcome in lymphangioleiomyomatosis. Am J Respir Crit Care Med 2001 164(6) 1072-1076. 

Pulmonary function test (PFT) abnormalities include varying degrees of partial or completely reversible airflow limitation. An irreversible restrictive or mixed restrictive and obstructive pattern occurs in the late stages of the disease (27). 

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