In this study, a miniature stirred tank bioreactor was designed for treatment of waste gas containing benzene, toluene and xylene. Oxygen mass transfer characteristics for various twin and single-impeller systems were investigated for 6 configurations in a vessel with 10 cm of inner diameter and working volume of 1.77L. Three types of impellers, namely, Rushton turbine, Pitched 4blades and Pitched 2blades impellers with downward pumping have been used. Deionized water was used as a liquid phase. With respect to other independent variables such as agitation speed, aeration rate, type of sparger, number of impellers, the relative performance of these impellers was assessed by comparing the values of (KLa) as a key parameter. Based on the experimental data, empirical correlations as a function of the operational conditions have been proposed, to study the oxygen transfer rates from air bubbles generated in the bioreactor. It was shown that twin Rushton turbine configuration demonstrates superior performance (23% to 77% enhancement in KLa) compared with other impeller compositions and that sparger type has negligible effect on oxygen mass transfer rate. Agitation speeds of 400 to 800 rpm were the most efficient speeds for oxygen mass transfer in the stirred bioreactor.

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The present study examined the biodegradation rate of benzene vapors in a two phase stirred tank bioreactor by a bacterial consortium obtained from wastewater of an oil industry refinery house. Initially, the ability of the microbial consortium for degrading benzene was evaluated before running the bioreactor. The gaseous samples from inlet and outlet of bioreactor were directly injected into a gas chromatograph to determine benzene concentrations. Carbone oxide concentration at the inlet and outlet of bioreactor were also measured with a CO2 meter to determine the mineralization rate of benzene. Influence of the second non-aqueous phase (silicon oil) has been emphasized, so at the first stage the removal efficiency (RE) and elimination capacity (EC) of benzene vapors were evaluated without any organic phase and in the second stage, 10% of silicon oil was added to bioreactor media as an organic phase. Addition of silicon oil increased the biodegradation performance up to an inlet loading of 5580 mg/m3, a condition at which, the elimination capacity and removal efficiency were 181 g/m3/h and 95% respectively. The elimination rate of benzene increased by 38% in the presence of 10% of silicone oil. The finding of this study demonstrated that two phase partition bioreactors (TPPBs) are potentially effective tools for the treatment of gas streams contaminated with high concentrations of poorly water soluble organic contaminant, such as benzene.

Background: Lead poisoning impairs memory and learning. Objectives: The protective effect of natural zeolite clinoptilolite on memory and learning impairment in rats exposed to lead acetate was investigated. Materials and Methods: 60 male Wistar rats in six groups treated for 2 months with diets contained different ratios of natural zeolite(i.e. 5% or 12.5%), and %0.2 lead acetate (LA) concentrations. behavioral test was evaluated by passive avoidance learning method in shuttle box at 6, 12, 24, 48 hours, and one week after the shock test. Results: digestive exposure with 0.2% lead acetate in the presence of zeolite additive had no effect on the rats' memory performance (P < 0.05). Adding 5 and 12.5%w/w of natural zeolite to the rats' feed improved short-term, medium-term, and long-term memory performance (P < 0.05) compared to the control group. Conclusion: observed improvement in memory function can be considered in part as the indirect effects of cation exchange or adsorption property of zeolites.

IntroductionMaximum oxygen consumption shows the maximum oxygen rate of muscle oxygenation that is acceptable in many cases, to measure the fitness between person and the desired job. Given that medical emergencies are important, and difficult jobs in emergency situations require people with high physical ability and readiness for the job, the aim of this study was to evaluate the maximum oxygen consumption, to determine the ability of work type among students of medical emergencies in Qazvin in 2016.MethodsThis study was a descriptive – analytical, and in cross-sectional type conducted among 36 volunteer students of medical emergencies in Qazvin in 2016. After necessary coordination for the implementation of the study, participants completed health questionnaires and demographic characteristics and then the participants were evaluated with step tests of American College of Sport Medicine (ACSM). Data analysis was done by SPSS version 18 and U-Mann-Whitney tests, Kruskal-Wallis and Pearson correlation coefficient.ResultsAverage of maximum oxygen consumption of the participants was estimated 3.15±0.50 liters per minute. 91.7% of medical emergencies students were selected as appropriate in terms of maximum oxygen consumption and thus had the ability to do heavy and too heavy work. Average of maximum oxygen consumption evaluated by the U-Mann-Whitney test and Kruskal-Wallis, had significant relationship with age (p<0.05) and weight groups (p<0.001). There was a significant positive correlation between maximum oxygen consumption with weight and body mass index (p<0.001).ConclusionThe results of this study showed that demographic variables of weight and body mass index are the factors influencing the determination of maximum oxygen consumption, as most of the students had the ability to do heavy, and too heavy work. Therefore, people with ability to do average work are not suitable for medical emergency tasks.

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Background: Noise at Intensive Care Units (ICU) has an adverse effect on patients and ICU staff. There are some evidences that sleep, recovery from critical illness and average background noise in hospitals as recommended by the US Environmental Protection Agency (EPA) and World Health Organization (WHO) should not exceed 30 A-weighted decibel (dBA) and peaks during night time should be less than 40 dBA. This survey was conducted to measure noise levels and their relationship with the time of the day and location in the ICU. Objectives: The objectives of this study were to measure noise levels and evaluate their relationship with time of day and location in the ICU. Materials and Methods: This cross sectional study was conducted in a public university hospital, namely Qazvin University of Medical Sciences, Qazvin, Iran. Noise levels were measured with SLM Sound level meter (model: Tes-1443) during 24 hours with the equivalent sound level (LEQ), maximum (Max) and peak sound pressure based on the ISO 9612.this tool can measure in the range of 30 to 110 dB dynamic network. While frequency A, fast time scale networks with 125 ms fast response microphones were selected. This method says that measuring point must have distance 1.5 meter from the wall at a height of 1.25 m above ground level. At the bedside of patients measurement done by 3 TES model 1353 H Tool by a Taiwanese company. Results: This survey showed that the Equivalent Sound Level (Leq) in ICU was much higher than the standard level. The Maximum Sound Level (Lmax) in most places was 84 -89 dBA and just in one measurement in the Internal ICU reached 90 dB. The average level of Leq in ICU was 70 dB. Conclusions: Equivalent noise level and Noise Criteria in ward remarkably exceeds the standards levels. This condition will be produce Dangerous circumstances for admitted patients in ward.