H Jürgen Kreuzer | PubMed Health

PubMed2006

Digital in-line holographic microscopy.

We first briefly review the state of the art of digital in-line holographic microscopy (DIHM) with numerical reconstruction and then discuss some technical issues, such as lateral and depth resolution, depth of field, twin image, four-dimensional tracking, and reconstruction algorithm. We then present a host of examples from microfluidics and biology of tracking the motion of spheres, algae, and bacteria. Finally, we introduce an underwater version of DIHM that is suitable for in situ studies in an ocean environment that show the motion of various plankton species.

Journal Article↗

PubMed2003

Hydroxide ion adsorption on self-assembled monolayers.

It is argued, on the basis of density functional calculations, that a self-assembled monolayer of oligo(ethylene glycol) or n-alkanes in contact with water will preferentially adsorb hydroxyl ions (either from autoionization of water or added to the solution) on both methoxy- and hydroxide-terminated endgroups, thus charging the surface region of the SAM negatively with an estimated charge density of about 1 microC/cm(2) in agreement with recent experiments. The negative charging can explain long-ranged forces between opposing SAM surfaces. On dense SAMs, hydroxyl ions are highly mobile. Hydronium ions can absorb by penetration into the SAM provided there is enough lateral space for their encapsulation. The important role of hydration is demonstrated by calculating the excess binding energy of adsorption using a Born-Haber cycle.

Journal Article↗