120 research outputs found

    High-Resolution Measurements of e+ + H2O Total Cross Section

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    Using a purely positron beam, the total cross section of positrons scattering from H2O has been measured for the first time with a high angular discrimination (≃1°) against forward scattered projectiles. Results are presented in the energy range (10-300) eV. Significant deviations from previous measurements are found which are, if ascribed entirely to the angular acceptances of various experimental systems, in quantitative accord with ab initio theoretical predictions of the differential elastic scattering cross section

    Re-evaluation of the Mesozoic complexes of Darnó Hill (NE Hungary) and comparisons with Neotethyan accretionary complexes of the Dinarides and Hellenides – preliminary data

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    Abstract The Mesozoic complex of Darnó Hill area in NE Hungary, according to well core documentation, is made up of two units. The upper unit, the Darnó Unit s.s., consists predominantly of blocks of ophiolitic rocks (pillow and massive basalt, gabbro) and subordinate abyssal sediments (red radiolarite and red pelagic mudstone of either Ladinian–Carnian or Bathonian–Callovian age, as well as bluish-grey, sometimes blackish siliceous shale of the latter age). The basalt is geochemically of MOR type, based on earlier evaluations. However, it comes in two types: reddish or greenish amygdaloidal pillow basalts with peperitic facies containing reddish micritic limestone inclusions, and green basalts without any sedimentary carbonate inclusion. The former type is probably MiddleTriassic, advanced rifting stage-related basalt, whereas the latter is probably of Jurassic age, corresponding to the Szarvaskõ-type basalt of the western Bükk Mountains. Pre-Miocene presence of an ultramafic sheet above the complex is indicated by serpentinite pebbles in the Lower Miocene Darnó Conglomerate. The lower unit, corresponding to the Mónosbél Unit of the western Bükk Mountains, consists of lower slope and toe-of-slope type sediments: dark grey shale and bluish-grey siliceous shale of Jurassic age, both showing distal turbiditic character, with frequently interbedded carbonate turbidites and debris flow deposits containing cm- to dm-sized limestone and micaceous sandstone clasts. One to ten m-sized slide blocks of reddish, siliceous Triassic Bódvalenke-type limestone associated with the above-mentioned reddish, amygdaloidal basalt also occur. In one of the studied cores a block comprising evaporitic siliciclastics akin to those of the Middle Permian Szentlélek Formation and black, fossiliferous limestone similar to the Upper Permian Nagyvisnyó Limestone Formation of the Bükk Mountains, was also encountered. A preliminary comparison with similar Triassic advanced rifting-type basalt and limestone/ radiolarite of the western ophiolite zone of the Balkan Peninsula is presented (Fig. 1): the Zagorje region of NW Croatia, the Zlatibor-Zlatar Mountains of SW Serbia, and the North Pindos and Othrys Mountains, as well as Euboea Island, of Northern Greece. We propose the terms "Loggitsi Basalt" for such Triassic basalt containing peperitic facies, after the village of Loggitsion located in the central part of the Othrys Mts, and "Bódvalenke Limestone" for the transitional facies between Hallstatt Limestone and Triassic red radiolarite, after the village of Bódvalenke located in the Rudabánya Hills. The northwesternmost occurrence of both of these typical Neotethyan formations can be found in NE Hungary (Darnó Hill and Bódva Unit of Rudabánya Hills, respectively)

    High-Resolution Measurements of e++ H2 O Total Cross Section

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    Using a purely electrostatic positron beam, the total cross section of positrons scattering from H2O has been measured for the first time with a high angular discrimination (≃1°) against forward scattered projectiles. Results are presented in the energy range (10-300) eV. Significant deviations from previous measurements are found which are, if ascribed entirely to the angular acceptances of various experimental systems, in quantitative accord with ab initio theoretical predictions of the differential elastic scattering cross section. © 2016 American Physical Society

    Letter to the Editor: 1H and 15N sequential assignment and solution secondary structure of 15N labelled human pancreatic ribonuclease

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    Several members of the RNase A (bovine pancreatic ribonuclease) superfamily exhibit anticancer activity. Among the mammalian members of the superfamily, most of the antitumour activity studies have been carried out with a dimeric RNase from bovine seminal vesicles (BS-RNase) (Youle and D’Alessio, 1997). These studies show that dimer formation is crucial for cytotoxicity. Investigations are underway to transfer by protein engineering the structural determinants responsible for the antitumour activity of BS-RNase to a human immunocompatible backbone (Piccoli et al., 1999). Knowledge of the 3D structures of the involved proteins is central to rationally fulfil this objective. As a first step, human pancreatic ribonuclease (HPRNase), a 127-residue monomeric protein (Beintema et al., 1984) was constructed (Russo et al., 1993). The expressed recombinant protein was undistinguishable from the natural product isolated from human pancreas (Weickmann et al., 1981). Here, we present the assignment of practically all of its 1H and 15N spectral resonances, as well as its secondary structure in aqueous solution. The cytotoxic activity of ribonucleases has been related to their ability to evade the cytosolic ribonuclease inhibitor (RI) (Murthy and Sirdeshmukh, 1992). The structure of HP-RNase will be useful to introduce changes in it in order to increase its resistance to RI.This work was supported by the European Commission under the INCO-Copernicus Project No. IC15 CT 96-0903. The assistance of the Ministerio de Asuntos Exteriores (Spain) and OMFB (Hungary) (project E26/97) is gratefully acknowledged
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