Варианты полиморфных изменений генов р53, XRCC1 и XPD у детей с острым лимфобластным лейкозом

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Isolation and purification of Cu-free methanobactin from Methylosinus trichosporium OB3b

<p>Abstract</p> <p>Background</p> <p>The isolation of highly pure copper-free methanobactin is a prerequisite for the investigation of the biogeochemical functions of this chalkophore molecule produced by methane oxidizing bacteria. Here, we report a purification method for methanobactin from <it>Methylosinus trichosporium </it>OB3b cultures based on reversed-phase HPLC fractionation used in combination with a previously reported resin extraction. HPLC eluent fractions of the resin extracted product were collected and characterized with UV-vis, FT-IR, and C-1s NEXAFS spectroscopy, as well as with elemental analysis and ESI-MS.</p> <p>Results</p> <p>The results showed that numerous compounds other than methanobactin were present in the isolate obtained with resin extraction. Molar C/N ratios, mass spectrometry measurements, and UV-vis spectra indicated that methanobactin was only present in one of the HPLC fractions. On a mass basis, methanobactin carbon contributed only 32% to the total organic carbon isolated with resin extraction. Our spectroscopic results implied that besides methanobactin, the organic compounds in the resin extract comprised breakdown products of methanobactin as well as polysaccharide-like substances.</p> <p>Conclusion</p> <p>Our results demonstrate that a purification step is indispensable in addition to resin extraction in order to obtain pure methanobactin. The proposed HPLC purification procedure is suitable for semi-preparative work and provides copper-free methanobactin.</p

Spectromicroscopy beamline at ELETTRA: Performances achieved at the end of commissioning

In the course of 1998, the Spectromicroscopy beamline at ELETTRA completed commissioning and succeeded in performing its first test experiments. The beamline is designed to perform photoemission experiments with high spatial resolution, which is obtained by focusing the radiation in a small spot on the sample by means of a multilayer-coated Schwarzschild Objective. Three objectives are currently available; these operate at photon energies of 74, 95, and 110 eV. A review is presented of the performances achieved together with an outlook on the future upgrades of the microscope. The smallest achievable spot size is currently 0.5 mu m. At present, the limit to the spatial resolution is due to aberrations caused by figure errors of the objective. Typical counting rates in photoemission spectra, for example, on the Au 5d peak, are of the order of 10(4)-10(5) counts per second with an energy resolution of the order of 100-200 meV. Among the first experiments in which p- and n-type GaAs layers of 0.25 mu m thickness were imaged. (C) 2000 American Institute of Physics. [S0034-6748(00)04001-6]

Recent Developments In Scanning Microscopy at Stony Brook

Abstract. Recent activities in scanning transmission x-ray microscopy at Stony Brook are outlined