نتایج جستجو برای: سنسنجی u pb

تعداد نتایج: 197330  

Journal: :Anais da Academia Brasileira de Ciencias 2007
Robert S Krymsky Moacir J B Macambira Jean-Michel Lafon Gérson S Estumano

Analytical procedures for U-Pb isotope dilution analyses at the Pará-Iso isotope geology laboratory of the Federal University of Pará (UFPA) are described in detail. The procedures are applied to zircon, titanite, rutile, apatite, columbite-tantalite and whole rock. Reagent preparation and chemical processing are done in clean-room conditions. Samples are dissolved using Teflon microcapsules in...

Journal: :Journal of environmental radioactivity 2017
Michael Foulkes Geoffrey Millward Samuel Henderson William Blake

Bioaccessible U, Th, Pb and the 238U decay products 214Pb and 210Pb have been determined, using a modified Unified BARGE Method (UBM), in waste solids and soils from an abandoned uranium mine in South West England, UK. Maximum aqua regia extractable concentrations for U, Th and Pb were 16,200, 3.8 and 4750 μg g-1, respectively. 238U had highest activity concentrations near the mine shaft, where...

Journal: :Chemistry 2008
Bernd Knobloch Barbara Nawrot Andrzej Okruszek Roland K O Sigel

Replacement of a non-bridging oxygen in the phosphate diester bond by a sulfur has become quite popular in nucleic acid research and is often used as a probe, for example, in ribozymes, where the normally essential Mg(2+) is partly replaced by a thiophilic metal ion to reactivate the system. Despite these widely applied rescue experiments no detailed studies exist quantifying the affinity of me...

2001
ETIENNE DELOULE MARC CHAUSSIDON BILLY P. GLASS CHRISTIAN KOEBERL

Isotopic compositions of U and Pb were determined for relict zircon inclusions recovered from Muong Nong-type tektites from the Australasian and North American strewn fields. These inclusions are generally opaque white with granular textures, probably representing mechanical disaggregation and/or local melting and recrystallization. All zircons have strongly discordant U–Pb isotopic ratios and ...

ژورنال: :پترولوژی 0
منیژه اسدپور منیژه اسدپور سید محمد پورمعافی ثریا هویس

توده نفوذی مافیک-اولترامافیک غازان، توده آذرین کوچکی در منتهی الیه شمال غرب پهنه سنندج-سیرجان در شمال غرب ایران، که در داخل سنگ های رسوبی پالئوزوئیک زیرین نفوذ کرده است. این توده شامل بخش مافیکی بدون کانه زایی و بخش اولترامافیک کانه زایی شده (حاوی اکسیدهای fe-ti) است. سنگ های مافیک شامل: پگماتیت گابرو تا میکروگابرو، متاگابرو و آنورتوزیت با مجموعه کانیایی ساده (پلاژیوکلاز، کلینوپیروکسن، ارتوپیرو...

Journal: :Journal of Analytical Atomic Spectrometry 2021

This paper presents U, Pb isotopic data of synthetic EARTHTIME solutions and natural reference materials together with suggestions how to ensure long-term intra- inter-laboratory reproducibility high-precision TIMS U–Pb geochronology.

2016
J. A. Cartwright Y. Amelin P. Koefoed M. Wadhwa

2009
T. Niihara H. Kaiden K. Misawa T. Sekine

Introduction: The age significance of isotope chro-nometers in shocked, but not totally molten, extrater-restrial materials is still a matter of debate [1–3]. Numerous isotopic data from different isotopic systems have been obtained for meteorites, but most meteorites with apparent shock ages do not show petrographic evidence of strong shock metamorphic overprint. Deutsh and Schärer [4] carried...

Journal: :International journal of oncology 2008
Irina Svechnikova Per M Almqvist Tomas J Ekström

The anti-neoplastic effects of histone deacetylase inhibitors (HDACi), Trichostatin A (TSA) and 4-phenylbutyrate (4-PB) on the human glioblastoma cell lines GBM-29, U-343 MG and U-343 MGa Cl. 2:6 were investigated. TSA and 4-PB induced apoptosis in the three cell lines in a dose- and time-dependent manner. Whereas caspase-3 activation was detected in all three cell lines, U-343 MG cells were mo...

2005
P. W. REINERS

Geochronology and thermochronology on detrital material provides unique constraints on sedimentary provenance, depositional ages, and orogenic evolution of source terrains. In this paper we describe a method and case-studies of measurement of both U/Pb and (U-Th)/He ages on single crystals of zircon that improves the robustness of constraints in each of these areas by establishing both formatio...

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