Search results for: Klaus Mayer

Items from 1 to 20 out of 60 results

article

Certification of Uranium Isotope Amount Ratios in a Suite of Uranium Ore Concentrate Certified Reference Materials

Ruoxi Zhang, Kenny Nadeau, Eduardo Amilcar Gautier, Paola Alejandra Babay, more

Geostandards and Geoanalytical Research > 46 > 1 > 43 - 56

In this study, data from thirteen laboratories from around the world are presented for a successful certification of uranium isotope ratios in uranium ore concentrate (UOC) certified reference materials from the National Research Council Canada. Different mass spectrometric measurement principles (including SF‐ICP‐MS, quadruple ICP‐MS, TIMS, MC‐ICP‐MS, SIMS and AMS) and measurement procedures were...

article

Measurement of production date (age) of nanogram amount of uranium

Zsolt Varga, Maria Wallenius, Adrian Nicholl, Klaus Mayer, more

Journal of Radioanalytical and Nuclear Chemistry > 2019 > 322 > 3 > 1585-1591

JRC-Karlsruhe obtained a swipe sample from a highly enriched uranium seizure, which had taken place in 2011. Due to the very low amount of uranium (nanograms) a new method needed to be developed to determine the U production date (age). The particles on the swipe were collected on a pyrolytic graphite planchet using a vacuum impactor and they were subsequently leached with ccHNO₃. The “bulk” U isotopic...

article

Characterization of californium sources by gamma spectrometry: relevance for nuclear forensics

Andrei I. Apostol, Jozsef Zsigrai, Janos Bagi, Michal Brandis, more

Journal of Radioanalytical and Nuclear Chemistry > 2019 > 321 > 2 > 405-412

High-resolution gamma spectrometry was used to study characteristics of californium neutron sources—age, isotopic composition and impurity radionuclides, as well as the effect of the isotopic composition on uncertainties involved in age determination. These characteristics are relevant during criminal investigations related to californium sources found outside of regulatory control. Age determination...

article

Measurement of the ²³¹Pa/²³⁵U ratio for the age determination of uranium materials

Zsolt Varga, Adrian Nicholl, Erich Hrnecek, Maria Wallenius, more

Journal of Radioanalytical and Nuclear Chemistry > 2018 > 318 > 3 > 1565-1571

The paper describes the age (production date) determination of uranium reference materials using the ²³¹Pa/²³⁵U ratio. Direct addition of ²³⁷Np in secular equilibrium with its ²³³Pa daughter was chosen instead of the regular milking of ²³⁷Np to avoid possible loss of Pa. Sample preparation consists of a fast, one-step procedure. The developed method using ICP-MS for the measurement of ²³¹Pa is more...

article

The application of radiochronometry during the 4th collaborative materials exercise of the nuclear forensics international technical working group (ITWG)

Michael J. Kristo, Ross Williams, Amy M. Gaffney, Theresa M. Kayzar-Boggs, more

Journal of Radioanalytical and Nuclear Chemistry > 2018 > 315 > 2 > 425-434

In a recent international exercise, 10 international nuclear forensics laboratories successfully performed radiochronometry on three low enriched uranium oxide samples, providing 12 analytical results using three different parent-daughter pairs serving as independent chronometers. The vast majority of the results were consistent with one another and consistent with the known processing history of...

article

Phreatic activity and hydrothermal alteration in the Valley of Desolation, Dominica, Lesser Antilles

Klaus Mayer, Bettina Scheu, Tim I. Yilmaz, Cristian Montanaro, more

Bulletin of Volcanology > 2017 > 79 > 12 > 1-19

Phreatic eruptions are possibly the most dramatic surface expressions of hydrothermal activity, and they remain poorly understood. The near absence of precursory signals makes phreatic eruptions unpredictable with respect to both time and magnitude. The Valley of Desolation (VoD), Dominica, located close to the Boiling Lake, the second largest high-temperature volcanic crater lake in the world, hosts...

article

Hydrothermal activity and subsoil complexity: implication for degassing processes at Solfatara crater, Campi Flegrei caldera

Cristian Montanaro, Klaus Mayer, Roberto Isaia, Marceau Gresse, more

Bulletin of Volcanology > 2017 > 79 > 12 > 1-20

The Solfatara area and its fumaroles are the main surface expression of the vigorous hydrothermal activity within the active Campi Flegrei caldera system. At depth, a range of volcanic and structural processes dictate the actual state of the hydrothermal system below the crater. The presence of a large variety of volcanic products at shallow depth (including pyroclastic fallout ash beds, pyroclastic...

article

From plant genomes to phenotypes

Marie Bolger, Rainer Schwacke, Heidrun Gundlach, Thomas Schmutzer, more

Journal of Biotechnology > 2017 > 261 > C > 46-52

Recent advances in sequencing technologies have greatly accelerated the rate of plant genome and applied breeding research. Despite this advancing trend, plant genomes continue to present numerous difficulties to the standard tools and pipelines not only for genome assembly but also gene annotation and downstream analysis.Here we give a perspective on tools, resources and services necessary to assemble...

article

The desert plant Phoenix dactylifera closes stomata via nitrate‐regulated SLAC1 anion channel

Heike M. Müller, Nadine Schäfer, Hubert Bauer, Dietmar Geiger, more

New Phytologist > 216 > 1 > 150 - 162

Date palm Phoenix dactylifera is a desert crop well adapted to survive and produce fruits under extreme drought and heat. How are palms under such harsh environmental conditions able to limit transpirational water loss? Here, we analysed the cuticular waxes, stomata structure and function, and molecular biology of guard cells from P. dactylifera. To understand the stomatal response to the water...

article

Identification of uranium signatures relevant for nuclear safeguards and forensics

Zsolt Varga, Judit Krajkó, Maxim Peńkin, Márton Novák, more

Journal of Radioanalytical and Nuclear Chemistry > 2017 > 312 > 3 > 639-654

The paper describes the applicability of different characteristics (signatures) in nuclear safeguards and forensics for assessment of uranium material provenance in terms of production process. The study follows a uranium ore concentrate production from an ore to a U₃O₈ product. It turned out that rare-earth elemental pattern, radiochronometry (age of ore body and material production date), sulphur...

article

A multidisciplinary approach to quantify the permeability of the Whakaari/White Island volcanic hydrothermal system (Taupo Volcanic Zone, New Zealand)

Michael J. Heap, Ben M. Kennedy, Jamie I. Farquharson, James Ashworth, more

Journal of Volcanology and Geothermal Research > 2017 > 332 > C > 88-108

Our multidisciplinary study aims to better understand the permeability of active volcanic hydrothermal systems, a vital prerequisite for modelling and understanding their behaviour and evolution. Whakaari/White Island volcano (an active stratovolcano at the north-eastern end of the Taupo Volcanic Zone of New Zealand) hosts a highly reactive hydrothermal system and represents an ideal natural laboratory...

article

Hydrothermal alteration of surficial rocks at Solfatara (Campi Flegrei): Petrophysical properties and implications for phreatic eruption processes

Klaus Mayer, Bettina Scheu, Cristian Montanaro, Tim I. Yilmaz, more

Journal of Volcanology and Geothermal Research > 2016 > 320 > C > 128-143

Solfatara crater is located within the Campi Flegrei caldera to the west of Naples (Italy). It is one of the largest fumarolic manifestations known, and the rocks hosting the hydrothermal system are affected by intense hydrothermal alteration. Alteration can result in changes of degassing behavior, and in the formation of a cap rock thereby increasing the probability of phreatic eruptions. Here, we...

article

Application of the angle measure technique as image texture analysis method for the identification of uranium ore concentrate samples: New perspective in nuclear forensics

Lorenzo Fongaro, Doris Mer Lin Ho, Knut Kvaal, Klaus Mayer, more

Talanta > 2016 > 152 > C > 463-474

The identification of interdicted nuclear or radioactive materials requires the application of dedicated techniques. In this work, a new approach for characterizing powder of uranium ore concentrates (UOCs) is presented. It is based on image texture analysis and multivariate data modelling. 26 different UOCs samples were evaluated applying the Angle Measure Technique (AMT) algorithm to extract textural...

chapter

The Arabidopsis Genome and Its Use in Cereal Genomics

Klaus Mayer, Stephen Rudd, Heiko Schoof

Cereal Genomics > 515-534

article

Investigation of sulphur isotope variation due to different processes applied during uranium ore concentrate production

Judit Krajkó, Zsolt Varga, Maria Wallenius, Klaus Mayer, more

Journal of Radioanalytical and Nuclear Chemistry > 2016 > 309 > 3 > 1113-1121

The applicability and limitations of sulphur isotope ratio as a nuclear forensic signature have been studied. The typically applied leaching methods in uranium mining processes were simulated for five uranium ore samples and the n(³⁴S)/n(³²S) ratios were measured. The sulphur isotope ratio variation during uranium ore concentrate (UOC) production was also followed using two real-life sample sets obtained...

article

IRMM-1000a and IRMM-1000b uranium reference materials certified for the production date. Part I: methodology, preparation and target characteristics

Zsolt Varga, Célia Venchiarutti, Adrian Nicholl, Judit Krajkó, more

Journal of Radioanalytical and Nuclear Chemistry > 2016 > 307 > 2 > 1077-1085

The paper describes the preparation and production of the reference materials, IRMM-1000a and IRMM-1000b, certified for the production date based on the ²³⁰Th/²³⁴U radiochronometer in compliance with ISO Guide 34:2009. The production date of the reference materials corresponds to the last separation of ²³⁰Th from ²³⁴U, i.e. when the initial daughter nuclide content in the material was finally removed...

article

Plutonium age dating (production date measurement) by inductively coupled plasma mass spectrometry

Zsolt Varga, Adrian Nicholl, Maria Wallenius, Klaus Mayer

Journal of Radioanalytical and Nuclear Chemistry > 2016 > 307 > 3 > 1919-1926

This paper describes rapid methods for the determination of the production date (age dating) of plutonium (Pu) materials by inductively coupled plasma mass spectrometry (ICP-MS) for nuclear forensic and safeguards purposes. One of the presented methods is a rapid, direct measurement without chemical separation using ²³⁵U/²³⁹Pu and ²³⁶U/²⁴⁰Pu chronometers. The other method comprises a straightforward...

article

Ribosome quality control is a central protection mechanism for yeast exposed to deoxynivalenol and trichothecin

Karl G. Kugler, Zeljkica Jandric, Reinhard Beyer, Eva Klopf, more

BMC Genomics > 2016 > 17 > 1 > 1-17

Background The trichothecene mycotoxins deoxynivalenol (DON) and trichothecin (TTC) are inhibitors of eukaryotic protein synthesis. Their effect on cellular homeostasis is poorly understood. We report a systematic functional investigation of the effect of DON and TTC on the yeast Saccharomyces cerevisiae using genetic array, network and microarray analysis. To focus the genetic analysis on intracellular...

article

A synteny‐based draft genome sequence of the forage grass Lolium perenne

Stephen L. Byrne, Istvan Nagy, Matthias Pfeifer, Ian Armstead, more

The Plant Journal > 84 > 4 > 816 - 826

Here we report the draft genome sequence of perennial ryegrass (Lolium perenne), an economically important forage and turf grass species that is widely cultivated in temperate regions worldwide. It is classified along with wheat, barley, oats and Brachypodium distachyon in the Pooideae sub‐family of the grass family (Poaceae). Transcriptome data was used to identify 28 455 gene models, and we utilized...

article

Titelbild: Uran aus deutschen Nuklearprojekten der 1940er Jahre – eine nuklearforensische Untersuchung (Angew. Chem. 45/2015)

Klaus Mayer, Maria Wallenius, Klaus Lützenkirchen, Joan Horta, more

Angewandte Chemie > 127 > 45 > 13331 - 13331

Nuklearforensik verfolgt die Spur zweier Uranblöcke zu den ersten deutschen Kernreaktionsexperimenten in den 1940er Jahren zurück. In der Zuschrift auf S. 13654 ff. vergleichen M. Wallenius et al. die makroskopischen Eigenschaften der Proben mit Literaturangaben, und sie bestimmen den Herstellungszeitpunkt und die Uranquelle.

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INFONA - science communication portal

Search results for: Klaus Mayer

Certification of Uranium Isotope Amount Ratios in a Suite of Uranium Ore Concentrate Certified Reference Materials

Measurement of production date (age) of nanogram amount of uranium

Characterization of californium sources by gamma spectrometry: relevance for nuclear forensics

Measurement of the ²³¹Pa/²³⁵U ratio for the age determination of uranium materials

The application of radiochronometry during the 4th collaborative materials exercise of the nuclear forensics international technical working group (ITWG)

Phreatic activity and hydrothermal alteration in the Valley of Desolation, Dominica, Lesser Antilles

Hydrothermal activity and subsoil complexity: implication for degassing processes at Solfatara crater, Campi Flegrei caldera

From plant genomes to phenotypes

The desert plant Phoenix dactylifera closes stomata via nitrate‐regulated SLAC1 anion channel

Identification of uranium signatures relevant for nuclear safeguards and forensics

A multidisciplinary approach to quantify the permeability of the Whakaari/White Island volcanic hydrothermal system (Taupo Volcanic Zone, New Zealand)

Hydrothermal alteration of surficial rocks at Solfatara (Campi Flegrei): Petrophysical properties and implications for phreatic eruption processes

Application of the angle measure technique as image texture analysis method for the identification of uranium ore concentrate samples: New perspective in nuclear forensics

The Arabidopsis Genome and Its Use in Cereal Genomics

Investigation of sulphur isotope variation due to different processes applied during uranium ore concentrate production

IRMM-1000a and IRMM-1000b uranium reference materials certified for the production date. Part I: methodology, preparation and target characteristics

Plutonium age dating (production date measurement) by inductively coupled plasma mass spectrometry

Ribosome quality control is a central protection mechanism for yeast exposed to deoxynivalenol and trichothecin

A synteny‐based draft genome sequence of the forage grass Lolium perenne

Titelbild: Uran aus deutschen Nuklearprojekten der 1940er Jahre – eine nuklearforensische Untersuchung (Angew. Chem. 45/2015)

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