Light Focusing through Scattering Media by Particle Swarm Optimization

We demonstrate light focusing through scattering media by introducing particle swarm optimization for modulat- ing the phase wavefront. Light refocusing is simulated numerically based on the angular spectrum method and the circular Gaussian distribution model of the scattering media. Experimentally, a spatial light modulator is used to control the phase of incident light, so as to make the scattered light converge to a focus. The influence of divided segments of input light and the effect of the number of iterations on light intensity enhancement are investigated. Simulation results are found to be in good agreement with the theoretical analysis for light refocusing.

Strain and Culture Medium Optimization for Production Enhancement of Prodiginines from Marine-Derived Streptomyces sp. GQQ-10

A mutant (GQQ-M6) of a Sponge-Derived streptomyces sp. GQQ-10 obtained by UV-induced mutation was used for producing prodiginines (PGs). Single factor experiments and orthogonal array design (OAD) methods were employed for medium optimization. In the single factor method, the effects of soluble starch, glucose, soybean flour, yeast extract and sodium acetate on PGs production were investigated individually. In the subsequent OAD experiments, the concentrations of these 5 key nutritional components combined with salinity were further adjusted. The mutant strain GQQ-M6 gave a 2.2-fold higher PGs production than that of the parent strain; OAD experiments offered a PGs yield of 61mg L-1, which was 10 times higher than that of the initial GQQ-10 strain under the original cultivation mode.

Experimental Design as a Tool for the Development of Citric Acid Production by Yarrowia lipolytica Using Glycerol as a Feedstock

Due to the scarcity of fossil fuels in the world, there is increasing interest in the commercial production of biodiesel, which leads to obtaining large amounts of glycerol as a byproduct. If not disposed of properly, glycerol can generate environmental impact. One of the promises, the application of the crude glycerol is the production of citric acid by microbial fermentation. Citric acid is industrially produced by a submerged fermentation process with Aspergillus niger, using sucrose as carbon source, but due to increased demand for citric acid, alternative processes using renewable sources or waste materials as substrates and the cultivation of yeast strains are being studied. The aim of the study was to determine the best culture condition for maximum citric acid synthesis and lower isocitric acid production from crude glycerol through experimental design tool. For this purpose, the yeast strain Yarrowia lipolytica IMUFRJ-50682 was cultivated in nitrogen-limited glycerol-based media. Therefore, glycerol and yeast extract concentrations and agitation speed were evaluated as independent variables. With pure glycerol, the highest citric acid production achieved was 16.5 g/L with an isocitric acid production of 7.7% （in relation to citric acid）. With crude glycerol, citric acid production reduced to 6.7 g/L because of higher biomass yield. Therefore, an increase in the initial carbon to nitrogen molar ratio from 714 to 1,561 was necessary to increase citric acid production to 9.2 g/L, reducing isocitric acid production and to achieve a yield of 0.41 g of citric acid per glycerol consumed. In this condition, less nitrogen source was used, reducing production costs.

Screening of enzyme activities for improvement of bread quality by potato peel addition to the yeast growth medium

Bread staling is defined as physicochemical changes in bread during storage,which results in undesirable changes in bread quality.It has always been one of the serious problems of the industrial sector throughout history.At the same time,vegetable waste,including potato peel(PP),is considered a serious problem to the environment.For this reason,PP has been used in this study to increase enzymatic activities of the yeast Saccharomyces cerevisiae,considered to have positive effects on bread quality.The goal of this study is to design a microbial system to facilitate human activities in industry,both joining the production of valuable enzymes by yeasts and recycling PP in the same medium.As a result,in our study,the highest growth rate of S.cerevisiae was recorded in the treatment with 2%PP present in the yeast growth medium.Also,no microbial growth,from baked bread samples,was observed due to proper storage of the loaves of bread in closed nylon bags at 4℃ for the duration of ten days.Moreover,treatments with 4%PP increased cellulase and invertase activities significantly(P<0.05),in comparison to treatments with no peel and with 2%peel.While amylase activity has been increased significantly(P<0.05)in treatment with 2%peel.In conclusion,treatment with 4%peel is recommended for improving enzymatic activity,in general,and bread quality in particular.