Role of Conformational Changes of Hexameric Bacterial Uridine Phosphorylases in Substrate Binding

Crystallography Reports - Crystals of mutants of uridine phosphorylase from Shewanella oneidensis MR-1 at the active-site threonine residue were obtained, and the three-dimensional structures of...     

Chemische synthese von nonadesoxyribonucleotiden mit den abgewandelten basen uracil, 5-bromuracil und 5-methylcytosin nach dem triester-verfahren

In order to investigate the interaction of Eco RII restriction and modification enzymes with synthetic DNA fragments three nonadeoxyribonucleotides containing the modified bases uracil, 5-bromouracil and 5-methylcytosine were synthesized according to the phosphate tri-ester approach using TPS/l-methylimidazole as the condensation agent. The patterns of these modified DNA fragments obtained by Maxam/Gilbert sequence technique are presented.     

Ultrafast Broadband Diagnostics of the Filling of the s Band at the Two-Photon Femtosecond Laser Excitation of a Gold Film

JETP Letters - The transmission of near infrared femtosecond laser pulses (wavelength of 800 nm) and supercontinuum radiation (300–750 nm) generated by them through a 50-nm gold film immersed...     

Micro‐Raman characterization of laser‐induced local thermo‐oxidation of thin chromium films

Micro‐Raman spectroscopy was applied to the characterization of the chemical composition and topography of protective oxide layers formed under atmospheric conditions on the surface of thin chromium films. Strips of the layers were produced by local thermal heating using focused sub‐picosecond pulsed laser radiation. It is shown that a CrO₂ layer is initially formed on the chromium surface at low light exposures. Increasing the exposure results in the transformation of the CrO₂ layer to Cr₂O₃. The influence of the etching conditions on the composition and thickness of the oxide layers is investigated. The topography of the CrO₂ and Cr₂O₃ oxide layers in transverse sections of the strips is demonstrated by the Raman mapping. Copyright © 2011 John Wiley & Sons, Ltd.     

Inspection of nano-sized SNOM-tips by optical far-field evaluation

High resolution optical microscopy has many interesting applications in solid state physics, low temperature physics, biology and semiconductor technology. Unfortunately, the lateral resolution of conventional microscopes is limited by the Rayleigh-limit. “Scanning nearfield optical microscopy” (SNOM) seems to be a promising new approach to characterize the properties of materials optically with a high lateral resolution of 50–100 nm. The most important part of such a microscope is the scanning probe (a special glass fiber tip). However, the quality of the optical fiber tip is of decisive importance. Since the production process of pulled and coated glass fiber tips is still highly empirical and error-prone, a technique would be useful to determine the tips’ quality before they are shipped to the user or mounted in the microscope. The tips’ apertures are smaller than λ/2 and therefore they cannot be measured in a non-destructive way by conventional optical microscopy. This paper discusses an easy and fast method for the optical characterization of common glass fiber SNOM tips. The effective aperture of the tip is measured from the far-field distribution of the emitted intensity recorded by a CCD target. A numerical model is introduced to solve this inverse task and a simple optical setup is presented to detect light emitted by the tip at an angle of up to 90° from the optical axis. Experimental investigation, near/far-field calculations and scanning electron microscope investigations show the working principle of this measurement technique for the analysis and evaluation of a typical nanostructured object.     

Modification of DNA by photoactivable aryl azides

Features of the interaction with DNA of photoactivable aryl azides having various substituents in the aromatic ring have been studied. The nature of the interaction with DNA and the degree of its modification depend substantially on the nature of these substituents. The results obtained can be used for obtaining DNA probes bearing various marker groups.Institute of Medical Genetics, Academy of Medical Sciences of USSR, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 259–263, March–April, 1989.