Evidence for coherent collective Rydberg excitation in the strong blockade regime

We report on strong van der Waals blockade in two-photon Rydberg excitation of ultracold magnetically trapped 87Rb atoms. The excitation dynamics was investigated for a large range of densities and laser intensities and shows a full saturation and a strong suppression with respect to single-atom behavior. The observed scaling of the initial increase with density and laser intensity provides evidence for coherent collective excitation. This coherent collective behavior, that was observed for up to several thousand atoms per blockade volume, is generic for all mesoscopic systems which are able to carry only one single quantum of excitation.     

NMR characterization of a Cu(I)-bound peptide model of copper metallochaperones: insights on the role of methionine

The first NMR structure of a Cu(I)-bound metallochaperone model with the conserved sequence MT/HCXXC revealed that at pH ～3.0 and ～6.8 Cu(I) binds through one Cys and the Met rather than the two Cys residues, differently than at pH ～8.5. This suggests a possible role of Met in metal transport.     

Linking photo- and redoxactive phthalocyanines covalently to graphene

"Green" graphene: For the first time, the covalent attachment of a light-harvesting and electron-donating phthalocyanine to the basal plane of few-layer graphene is reported. Physicochemical characterizations reveal an ultrafast charge separation from the photoexcited phthalocyanine to few-layer graphene followed by a slower charge recombination.     

Single Amino Acid Substitution Reveals Latent Photolyase Activity in Arabidopsis cry1

A quick switch: A single amino acid substitution at a conserved residue (D396N) of Arabidopsis cryptochrome-1 (Atcry1) confers single-stranded DNA repair activity in?vitro, conferring photolyase activity onto the cryptochrome. The mutant protein undergoes photoreduction of flavin to the fully reduced anionic form, similar to photolyases and unlike wild-type cryptochromes.     

The temperature dependence of the nuclear quadrupole interaction of 44Ti(EC)44Sc in rutile

The temperature dependence of the Nuclear Quadrupole Interaction on ⁴⁴Sc in rutile was measured by Time Differential Perturbed Angular Correlation in the temperature range from 300 K to 945 K. Whereas $\upomega _{\rm Q} = \mathrm{eQV}_{\rm zz}/4\rm \hbar$ with V_zz denoting the largest component of the electric field gradient tensor in magnitude increases with increasing temperature, the asymmetry parameter η remains essentially constant. This observation fits into the systematic with other probes provided the sign of V_zz is negative.     

In-line reference-delayed digital holography using a low-coherence light source

We present a holographic imaging device with a low-coherence light source that uses the reflection of the objective lens as reference illumination. This results in a simple setup and allows applications to microscopy with only small modifications of the setup for aberration measurements. In addition, it opens the prospects to in vivo ophthalmic imaging. We present in vitro experiments using a resolution test target to quantify the system performance. We demonstrate that we can achieve diffraction-limited resolution and show the possibility of aberration correction. We also present preliminary results using a scattering sample.     

Three‐Component Synthesis of Highly Functionalized 5‐Acetyloxazoles

By a flexible three‐component synthesis, alkoxy‐substituted enamides are easily available from lithiated alkoxyallenes, nitriles and carboxylic acids (see scheme). The treatment of these versatile intermediates with trifluoroacetic acid provided 5‐acetyloxazoles in moderate to good yields. Different substituents are possible at C‐2 and C‐5 and the 5‐acetyl group is a suitable handle for further synthetic transformations.

     

Comparing contact and dipolar interactions in a Bose-Einstein condensate

We have measured the relative strength epsilon dd of the magnetic dipole-dipole interaction compared with the contact interaction in a dipolar chromium Bose-Einstein condensate. We analyze the asymptotic velocities of expansion of the condensate with different orientations of the atomic magnetic moments. By comparing the experimental results with numerical solutions of the hydrodynamic equations for dipolar condensates, we obtain epsilon dd = 0.159+/-0.034. We use this result to determine the s-wave scattering length a = (5.08+/-1.06 x 10(-9)) m = (96+/-20) a0 of 52Cr. This is fully consistent with our previous measurements on the basis of Feshbach resonances and therefore confirms the validity of the theoretical approach used to describe the dipolar Bose-Einstein condensate.     

Chemikalien für die Lederherstellung. Vom Kollagen tierischer Häute zum Werkstoff Leder

Leather is a valuable material manufactured from collagen network of hides and skins by suitable chemical and physical processes. The article describes structure and reactivity of the most important leather chemicals, necessary to convert collagen into leather.