Comparison of the Continuous Flotation Performances of Saccharomyces-cerevisiae Lbg H620 and Dsm-2155 Strains

Saccharomyces cerevisiae LBG H620 and DSM 2155 strains were continuously cultivated under carbon (C)-limited, phosphorus (P)-limited and nitrogen (N)-limited growth conditions. Cell and protein concentrations in feed, foam, and residue as well as the degree of cell recovery and the rate of foaming were measured, and the concentration and enrichment factors were evaluated at different dilution rates (D). The LBG H620 cells were reduced, while the DSM 2155 cells were enriched in the foam. The highest concentration factors in DSM 2155 cells were attained if they were cultivated under strong P-limitation at a low D. Fairly high concentration factors were also found under C-limitation. Under N-limitation, low concentration factors were found with low Ds. At the beginning of the continuous cultivations, all of the cells were recovered, but with advancing time the degree of recovery and cell concentration and the enrichment factor ratio diminished. The cellular properties of the yeast were characterized by flow cytometry, and the surface properties by measurements of their hydrophobicity, electrophoretic mobility, and chemical composition (using X-ray photoelectron spectroscopy, XPS). These investigations indicated that the large difference in flotation between the two strains is due to different surface properties. Strain DSM 2155 has higher surface hydrophobicity and lower electrokinetic potential. Cell wall properties and the cell flotation depend on medium composition and age of the culture

Monolithic mode-locked laser diode for THz communication

International audienceA need for higher data rates in wireless applications necessitates fast technological development to meet this. One option for advancement is the use of higher carrier frequencies as this technique can incorporate previously established methods of data transfer such as modulation techniques. We show that generation and detection of multiple carrier frequencies in the THz range is possible using standard telecom equipment and a single mode-locked laser diode

Quantum cascade laser based active hyperspectral imaging for standoff detection of chemicals on surfaces

We employ active hyperspectral imaging using tunable mid-infrared (MIR) quantum cascade lasers for contactless identification of solid and liquid contaminations on surfaces. By collecting the backscattered laser radiation with a camera, a hyperspectral data cube, containing the spatially resolved spectral information of the scene is obtained. Data is analyzed using appropriate algorithms to find the target substances even on substrates with a priori unknown spectra. Eye-save standoff detection of residues of explosives and precursors over extended distances is demonstrated and the main purpose of our system. However, it can be applied to any substance with characteristic reflectance / absorbance spectrum. As an example, we present first results of monitoring food quality by distinguishing fresh and mold contaminated peanuts by their MIR backscattering spectrum