ABSTRACT
In this study, an electroscrubber was designed and experimented for evaluation of integrating particle and droplet charging effects separately and jointly on collection efficiency of a spray tower and also to discover the optimal condition. A homogenous concentration of relatively fine particles was introduced to influent air stream and electroscrubber efficiency in purifying them was determined through the measurement of input and output particles concentration. The effect of various conditions such as particles and droplets charging alone and together [bipolar] for several applied voltages has been studied. In all of experiments, the applied charging voltage has a key role in promotion of electroscrubber efficiency. Maximum collection efficiency has achieved for 15 Kilovolt [Kv]. The effectiveness of bipolar charging of particles and droplets with 15 Kv was higher than that of no-charging and singly charging. In other words, efficiency can be increased from 84.43% to 93.22 for total particles and from 50.8% to 75.16% for submicron particles. The maximum improvement of collection efficiency [42.2%] relates to bipolar charging of the initial size group with diameter smaller than 0.3 micrometer [microm] and the minimum [0.5%] to sizing group of 11 with diameter 4-5 microm. This approach can be an appropriate option for the purpose of purifying submicron particles in spray tower scrubbers
ABSTRACT
Infectious diseases are one of the most common causes of morbidity and mortality and the spread of resistant microorganisms is playing a significant role in this regard. The purpose of this study was to assess the trend in antimicrobial resistance of gram-positive bacteria at the main referral teaching hospital in Tehran during a 4-year period. All patients' biological isolates such as blood, urine, wound drainage, synovial fluid, sputum, and cerebrospinal fluid sent to the central laboratory of the hospital from 2007 to 2010 for identification and subsequently, antimicrobial susceptibility testing by Kirby-Bauer disc diffusion method were considered. All isolates [100%] of S. aureus were sensitive to vancomycin and linezolid and resistant to amoxicillin. The rate of S. aureus resistance to oxacillin increased from 60.78% in 2007 to 72% in 2010. All isolates of Streptococci in 2007 and 2008 were sensitive to vancomycin; while, 3.33% and 4.76% of Streptococci isolates were reported to be vancomycin-resistant in 2009 and 2010, respectively. Enterococci isolated from the entire specimens were identified to be sensitive to teicoplanin and linezolid and resistant to cloxacillin and oxacillin. The rates of Enterococci sensitivity to vancomycin were 90.91%, 81.25%, 86.67%, and 93.3% in 2007, 2008, 2009, and 2010, respectively. Changes of antibiotics sensitivity against g positive pathogens were significant during four years in this study. To minimize the spread of resistant gram positive pathogens, periodic and regular surveillance of antimicrobial resistance pattern is highly recommended.