Quantitative comparison of ammonia and 3-indoleacetic acid production in halophilic, alkalophilic and haloalkalophilic bacterial isolates in soil

In order to measure the concentration of ammonia production via corrected Nesslerization method and 3-indoleacetic acid as Salkowski method in halophilic, alkalophilic and haloalkalophilic bacterial isolates, soil samples were collected from six different areas of Khorasan Razavi and bacterial isolates isolated and purified using different growth medium accordingly. The alkalophiles isolates showed maximum ammonia production (0.055%) among the three groups of bacteria which this amount was 9.5 times of its average in haloalkalophiles isolates (0.0058%) and 13 times of ammonia production average in halophiles (0.004%). Mean comparison of the concentration3-indoleacetic acid production in three groups also showed that the most isolates of halophiles, alkalophiles and haloalkalophiles were IAA producer with 0.0003, 0.0001 and 0.0021percent respectively that the IAA amount in haloalkalophilic group was about 6 and 14.5 times of it in halophilic and alkalophilic isolates respectively. Equations to predict the concentration of ammonia and 3-indole acetic acid production was only significant in the haloalkalophilic isolates for ammonia production (P=0.046) and halophilic isolates for IAA production (P=0.015) under effect of electrical conductivity and pH in 0.05 probability level. Results represented that the multiple regression analysis for prediction of ammonia and IAA concentrations producing by isolates had not any significant performance in high and low concentrations under effect of electrical conductivity and pH. It seems that the uses of the two sensitive measuring methods (Nesslerization and Salkowski) after some modifications show promises and are recommend able in research due to their ease of implementation and relatively accurate results.Keywords: Alkalophiles; haloalkalophiles; halophiles; 3-indoleacetic acid; nesslerization method; salkowski method

Nitric oxide metabolite levels during the ectopic osteoinduction in rats

Abstract Nitric oxide (NO) is a cell-signaling molecule that has diverse biological functions. Recent evidence suggests that its production may regulate the metabolism of the osteoblasts and osteoclasts. The aim of this study was to evaluate levels of nitrite and nitrates (NO metabolites) during ectopic osteoinduction in rats. Eighteen male Sprague–Dawley rats (body weight 200–300 g) were used in this study. All animals were anesthetized and the right and left flank areas were shaved, and under aseptic conditions, a muscular pouch was created in each flank: the left was filled with 20 mg of demineralized bone matrix and the right remained empty (sham). Radiographs were taken at 2, 4, and 6 weeks after surgery to trace the ectopic bone formation and muscle mineralization. Blood samples were taken before (as baseline values) and at 2, 4, and 6 weeks after surgery. The mean values of NO metabolites after 6 weeks were significantly higher (p<0.05) than baseline data and at 2 weeks post-surgery. Results from this study indicate that the ectopic osteoinduction caused increased activity of the osteoblasts which subsequently caused increased serum levels of NO metabolites (nitrites and nitrates)

COVID-19 spread in a classroom equipped with partition – A CFD approach

In this study, the motion and distribution of droplets containing coronaviruses emitted by coughing of an infected person in front of a classroom (e.g., a teacher) were investigated using CFD. A 3D turbulence model was used to simulate the airflow in the classroom, and a Lagrangian particle trajectory analysis method was used to track the droplets. The numerical model was validated and was used to study the effects of ventilation airflow speeds of 3, 5, and 7 m/s on the dispersion of droplets of different sizes. In particular, the effect of installing transparent barriers in front of the seats on reducing the average droplet concentration was examined. The results showed that using the seat partitions for individuals can prevent the infection to a certain extent. An increase in the ventilation air velocity increased the droplets’ velocities in the airflow direction, simultaneously reducing the trapping time of the droplets by solid barriers. As expected, in the absence of partitions, the closest seats to the infected person had the highest average droplet concentration (3.80 × 10−8 kg/m3 for the case of 3 m/s)