Conformational change of membrane proteins leads to shape changes of red blood cells

High-resolution atomic force microscopy (AFM) allows a new insight into the surface of mammalian cells. Using the human red blood cell (RBC) as a model, we have demonstrated an important correlation between the conformation of membrane proteins measured from the external face of the cell and the cell shape.     

Hydrogen bonding in liquid water probed by resonant Auger-electron spectroscopy

We have measured resonant and off-resonant Auger-electron spectra of liquid water. Continuumlike transitions near and above the O1s vertical ionization energy are identified by the characteristic normal Auger-electron spectra. On the contrary, well-resolved spectator shifts of the main Auger-electron peak are observed at the liquid-water O1s absorption main edge and near the absorption pre-edge. The shifts of 1.4 and 1.9 eV arise from the localized nature of the excitation. Excited-state localization/delocalization is also discussed for the analogous vacuum ultraviolet (VUV) transitions, and we point out the similarities between x-ray and VUV absorption spectra of liquid water.     

Hydrogen bonds in liquid water studied by photoelectron spectroscopy

The authors report on photoelectron emission spectroscopy measurements of the oxygen 1s orbital of liquid water, using a liquid microjet in ultrahigh vacuum. By suitably changing the soft x-ray photon energy, within 600-1200 eV, the electron probing depth can be considerably altered as to either predominantly access the surface or predominantly bulk water molecules. The absolute probing depth in liquid water was inferred from the evolution of the O1s signal and from comparison with aqueous salt solution. The presence of two distinctive components in the core-level photoelectron spectrum, with significantly different binding energies, is revealed. The dominant contribution, at a vertical binding energy of 538.1 eV, was found in bulk and surface sensitive spectra. A weaker component at 536.6 eV binding energy appears to be present only in bulk water. Hartree-Fock calculations of O1s binding energies in different geometric arrangements of the water network are presented to rationalize the experimental distribution of O1s electron binding energies.     

On higher order variational analysis in one and three dimensions for soft boundaries

For some problems in liquid crystal physics we need to use the Euler equation and the corresponding boundary equation in the three-dimensional case with soft boundaries. As a further complication the free energy expression, which should be minimized, might contain some second-order and third-order derivatives. These higher-order derivatives will cause the spatial derivatives of the boundary normal to appear in the boundary equation. Explicit formulae are given for the Euler equation and the corresponding surface equations for a general case. As an example, the theory is applied to nematic liquid crystals, where the general Euler equations and surface molecular fields are derived, including the effects of an imposed electric field.     

Sehr einfaches syntheseprinzip für formyl-verzweigte kohlenhydrate vom streptose-typ

n-Butylvinyl ehters, prepared by Wittig olefination of aldos-3-ulose derivatives react upon osmium tetraoxide hydroxylation with immediate formation of

branched carbohydrates.     

Anwendung katalysierter Reaktionen zur halbquantitativen Bestimmung mit Hilfe der Ringofenmethode

Microchimica Acta - Katalysierte Reaktionen können in Kombination mit der Ringofen-Technik für qualitative und quantitative Zwecke angewendet werden. Hier wurde die sogenannte...     

Role of alkali cations for the excited state dynamics of liquid water near the surface

Time-resolved liquid jet photoelectron spectroscopy was used to explore the excited state dynamics at the liquid water surface in the presence of alkali cations. The data were evaluated with the help of ab initio calculations on alkali-water clusters and an extension of these results on the basis of the dielectric continuum model: 160 nm, sub-20 fs vacuum ultraviolet pulses excite water molecules in the solvent shell of Na(+) or K(+) cations and evolve into a transient hydrated complex of alkali-ion and electron. The vertical ionization energy of this transient is about 2.5 eV, significantly smaller than that of the solvated electron.     

Zur strahlenchemischen Zersetzung von in Wasser gelöstem und auf Aktivkohle adsorboiertem p-Chlorphenol

Im Rahmen dieser Arbeit wurde die strahlenchemische Zersetzung von in Wasser gelöstem und auf Aktivkohle adsorbiertem p-Chlorphenol untersucht.

Bei der γ-Bestrahlung einer wäßrigen p-Chlorphenollösung (C₀ = 500 ppm) erfolgt eine Dechlorierung. Parallel dazu verläuft die Bildung einer braunen Substanz, bei der es sich wahrscheinlich um Huminsäure oder ein Huminsäurederivat hundelt.

Auf Aktivkohle adsorbiertes p-Chlorphenol wird dagegen im untersuchten Beladungshöhenbereich (zwischen 19 und 45 mg p-Chlorphenol/g wasserfreie Kohle) unter den Bedingungen der strahlenchemisch induzierten Oxydation zu den Mineralisierungs-produkten Chlorid, Wasser und Kohlendioxid abgebaut. Neben der γendosis und der Beladungshöhe des p-Chlorphenols beeinflussen Texfur und Oberflächenchemie der verwendeten Aktivkohlen die Zersetzungsraten.