A new cell primo-culture method for freshwater benthic diatom communities

A new cell primo-culture method was developed for the benthic diatom community isolated from biofilm sampled in rivers. The approach comprised three steps: (1) scraping biofilm from river pebbles, (2) diatom isolation from biofilm, and (3) diatom community culture. With a view to designing a method able to stimulate the growth of diatoms, to limit the development of other microorganisms, and to maintain in culture a community similar to the original natural one, different factors were tested in step 3: cell culture medium (Chu No 10 vs Freshwater “WC” medium modified), cell culture vessel, and time of culture. The results showed that using Chu No 10 medium in an Erlenmeyer flask for cell culture was the optimal method, producing enough biomass for ecotoxicological tests as well as minimising development of other microorganisms. After 96 h of culture, communities differed from the original communities sampled in the two rivers studied. Species tolerant of eutrophic or saprobic conditions were favoured during culture. This method of diatom community culture affords the opportunity to assess, in vitro, the effects of different chemicals or effluents (water samples andindustrial effluents) on diatom communities, as well as on diatom cells, from a wide range of perspectives

Matter-wave Tests of the Gravitational Redshift in Space

A recent measurement of the gravitational redshift was based on interference of matter waves. Operation in microgravity can improve it by a factor of $10^5$ and, in some models, even $10^{10}$.Comment: Talk given at the Fifth Meeting on CPT and Lorentz Symmetry, at Indiana University, Bloomington, IN. Corrected problem with Figur

The implementation of sinusoidal PWM on single phase 5-level cascaded H-bridge multilevel inverter

In the new millennium era of technology, modern industrial devices are mostly based on electronic devices that are very sensitive to harmonics. The needs for a free-harmonics and high rating power source is extremely increased in the past few years to meet the requirement from the industries. An inverter which converts DC power to AC power is one of the power electronic devices that have been in the researchers’ radar for further improvement to generate a clean power source. An inverter can be broadly classified into single level inverter and multilevel inverter. A multilevel inverter as compared to a single level inverter has advantages like minimum harmonics distortion and higher power output. An implementation of cascaded h-bridge topology and a sinusoidal pulse�width modulation, synthesize a higher quality output power especially with multilevel configuration