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Abstract (1) Background: Oxygen supply is an important parameter to be considered in submerged cultures. This study evaluated the influence of different conditions for dissolved oxygen (DO) concentration on laccases activities and growth of Pleurotus sajor-caju PS-2001 in submerged process in stirred-tank bioreactor. (2) Methods: Initially, three different conditions were tested: uncontrolled DO and minimum levels of 30% and 80% of saturation, with the pH controlled between 4.5 and 7.0. (3) Results: Best results were observed at 30% DO (26 U mL-1 of laccases at 96 h), whereas higher mycelial biomass was observed at 30% and 80% DO (above 4.5 g L-1). Four different conditions of DO (uncontrolled, 10%, 30% and 50% of saturation) were tested at pH 6.5, with higher laccases activity (80 U mL-1 at 66 h) and lower mycelial growth (1.36 g L-1 at 90 h) being achieved with DO of 30%. In this test, the highest values for volumetric productivity and specific yield factor were determined. Under the different pH conditions tested, the production of laccases is favoured at DO concentration of 30% of saturation, while superior DO levels favours fungal growth. (4) Conclusion: The results indicate that dissolved oxygen concentration is a critical factor for the culture of P. sajor-caju PS-2001 and has important effects not only on laccases production but also on fungal growth.
Subject(s)
Dissolved Oxygen , Biomass , Bioreactors , Pleurotus/growth & development , Pleurotus/enzymology , Laccase/biosynthesisABSTRACT
Objective To measure the catalytic effect of ammonium salt solution on hydrogen production , and analyze the relationships between hydrogen concentration and oxygen concentration , oxidation-reduction potential , and pH in solution . Methods Magnesium and water reacted at different concentrations of NH4Cl, (NH4)2SO4, NH4HCO3,(NH4)2CO3, NaHCO3 and Na2SO3 in 40℃water bath for 0, 2, 4, 6, 8 and 10 hours, and above-mentioned four indicators of ammonium salt solution were measured after these reactions .Results The hydrogen concentration in the solution increased with the reaction time and the concentration of the ammonium salt solution .Oxygen concentration and oxidation-reduction potential decreased .The hydrogen concentration in the solution was significantly negatively correlated with the oxygen concentration (r=-0.984).pH increased with the hydrogen concentration in the ammonium salt solution .Conclusion The ammonium salt solution has a good catalytic effect on magnesium and water reaction .NH4Cl has the strongest catalytic effect under the same reaction conditions,followed by (NH4)2SO4, NH4HCO3 and (NH4)2CO3.Thus, this study can provide detailed data on hydrogen production in different solutions .
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Objective To measure the maximum dissolved oxygen concentration of the lithotripter to avoid visible air bubbles during lithotripsy.Methods The present situation of degassing of lithotripter and clinical requirements for water were introduced.Under the following conditions of 7.5 L water capacity,35 L/h water flow,ambient temperature 28 ℃,17 kV,60 shocks per minute,the lithotripter discharged 10 000 shocks continuously without a visible air bubble in the circulating water,then the dissolved oxygens in the water were measured by using AZ8403 dissolved oxygen meter.The maximum value of dissolved oxygen in the water was determined therefore without a visible air bubble.Results The visible tiny air bubble emerged during lithotripsy if the dissolved oxygen in the water was above 3.37 mg/L and ambient temperature was about 28 ℃;the bubble could be avoided if the dissolved oxygen was under 3.34 mg/L and ambient temperature was about 28 ℃.Conclusion The circulating water with dissolved oxygen concentration less [han 3 mig/L and about 28 ℃ ambient temnperature are recommended for the electromagnetic extracorporea] shock wave lithotripter during lithotripsy.
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Objective To verify the efficiency and stability of hydrogen-rich water preparation with hydrogen-rich rods. Methods ①Seven firenew hydrogen-rich rods were separately placed in seven plastic bottles, each filled with distilled water and soaked for 6 h, before the hydrogen concentration of the water was measured.This process was repeated 10 times.②After the hydrogen-rich rods with the strongest and weakest hydrogen product capacity were removed, the remaining 5 hydrogen-rich rods were placed separately into 5 plastic bottles filled with distilled water,put in a water bath pot at 20,40 and 60℃, respectively, and kept for 2, 4, 6, 8 and 10 h, respectively.Then, the hydrogen concentration, oxidation-reduction potential(ORP),and dissolved oxygen concentration(DO) were measured at various time points.③In order to determine the hydrogen emission rate from the hydrogen-rich water, the hydrogen-rich rods were constantly kept in some samples and the others were removed.All the sample bottle caps were kept open during the experimental process, and the hydrogen concentration was measured at such time points as 0, 10 and 30 min, 1, 2, 5, 12, 24, 30, 48 and 72 h, respectively.Results ①The hydrogen-rich rods used in this study could well meet the requirements.②When the environment temperature was kept constant, the hydrogen concentration of the water was increased with the soaking time of the hydrogen-rich rods, and the ORP of the water was reduced.However, the DO of the water was decreased with the rise of the environment temperature.③When the hydrogen-rich water was kept in opened plastic bottles with a 25 mm oral diameter, the hydrogen concentration of the samples with the hydrogen-rich rods reserved was almost about 0.50 ppm until 72 h, and that of the others was reduced to almost 0 ppm.Conclusion Our results demonstrate that the hydrogen-rich rods test is a simple and effective method for preparing hydrogen-rich water, which will be an valuable and useful method for using hydrogen-rich water in health promotion and prevention of chronic diseases.