Gesellschaft zur Förderung von Medizin-, Bio- und Umwelttechnologien

Imaging flow cytometry provides access to high-throughput imaging of bioparticles in continuous flow. High-quality images with maximum contrast and optical resolution can be obtained if the particles pass through the flow cell exactly within the focal plane of the imaging system. Microfluidic technologies enable particle focusing along a line or within a horizontal plane. This work explores the potential applications of hydrodynamic flow focusing and acoustofluidic particle focusing as complementary techniques for imaging flow cytometry (IFC). Therefore, the quality of particle focusing has been measured and analyzed in 3D by astigmatic microparticle imaging. In our 3D measuring system, a z-resolution of 10 μm was achieved with a measuring range of +/- 80 μm relative to the focal plane. A simple, but highly efficient method for z-calibration has been proposed and validated. Ultimately, both flow focusing approaches enable precise z-focusing of 10 μm-sized test particles into narrow lamellas with a standard deviation of 3 μm in the z-direction. At the same time, they cover complementary use cases, so that both methods are justified in their application.

Walter Hampele, Ruth Schefold, Haller Treppen, Schwäbisch Hall (Förderverein zur Erhaltung der mittelalterlichen Kirchen in Halle.V.) 1998. 48 S., 22 Radierungen.

Abstract Phototherapy involves exposure of the skin to light in order to treat various skin diseases such as psoriasis. In the 20th century, great advancements have been made in developing safe and effective narrowband ultraviolet B (NB‐UVB) phototherapy modalities. Targeted phototherapy delivers light exclusively to the affected skin and thereby avoids side effects on unaffected healthy areas. Recently, solid‐state UV light emitting diodes (UV LEDs) have the potential to become the light source of the future for targeted NB‐UVB phototherapy treatments.

Nafion is the most common material used as a proton exchange membrane in fuel cells. Yet, details of the transport pathways for protons and water in the inner membrane are still under debate. Overhauser Dynamic Nuclear Polarization (ODNP) has proven to be a useful tool for probing hydration dynamics and interactions within 5-8 Å of protein and soft material surfaces. Recently it was suggested that ODNP can also be applied to analyze surface water dynamics along Nafion's inner membrane. Here we interrogate the viability of this method for Nafion by carrying out a series of measurements relying on 1H nuclear magnetic resonance (NMR) relaxometry and diffusometry experiments with and without ODNP hyperpolarization, accompanied by other complementary characterization methods including small angle X-ray scattering (SAXS), thermal gravimetric analysis (TGA) of hydration, and proton conductivity by AC impedance spectroscopy. Our comprehensive study shows that commonly used paramagnetic spin probes-here, stable nitroxide radicals-for ODNP, as well as their diamagnetic analogues, reduce the inner membrane surface hydrophilicity, depending on the location and concentration of the spin probe. This heavily reduces the hydration of Nafion, hence increases the tortuosity of the inner membrane morphology and/or increases the activiation barrier for water transport, and consequently impedes water diffusion, transport, and proton conductivity.

Abstract Characterization of mesoporous materials today is routinely performed recording the adsorption isotherm of nitrogen at 77 K. The pore size distribution (PSD) can subsequently be determined using either thermodynamics or statistical mechanics based approaches. While nitrogen has evolved as the reference adsorptive, other gases are often used to extract more information from the isotherm. This contribution is focused on the calculation of a PSD from the water vapor isotherm. It is demonstrated that water adsorption provides accurate results comparable to the standard nitrogen adsorption.

UV phototherapy is a highly effective therapy option for the treatment of skin diseases. In this chapter light sources for and variants of dermatological phototherapy are introduced together with their indications and mechanisms of action. Moreover, the outcomes of clinical studies using novel UV emitters including UV-LEDs are discussed.