Annual Report 2011 - Institute of Radiochemistry

The Institute of Radiochemistry (IRC) is one of the seven institutes of the Helmholtz-Zentrum Dresden-Rossendorf (HZDR). The research activities are fully integrated into the “Nuclear Safety Research Program” of the Helmholtz Association and focused on the topic “Safety of Nuclear Waste Disposal”. The research objectives are to generate better process understanding and data for the long-term safety analysis of a nuclear waste disposal in the deep geological underground. A better knowledge about the dominating processes essential for radionuclide (actinide) mobilization and immobilization on the molecular level is needed for the assessment of the macroscopic processes which determine the transport and distribution of radioactivity in the environment. Special emphasis is put on the biological mediated transport of long-lived radionuclides in the geosphere and their interaction with different biosystems like biota and human organism for a better calculation of environmental and health risks. Advanced knowledge is needed for description of the processes dominating at the interfaces between geo- and bio-systems related to the distribution of long-lived radionuclides in various bio-systems along the food chain

Mögliche Rationen mit Nebenerzeugnissen für Schweine

Laut EU-Bio-Verordnung ist die tägliche Raufuttergabe Vorschrift. Darüber hinaus sollen im Öko-Landbau Abfallstoffe und Nebenerzeugnisse pflanzlichen und tierischen Ursprungs als Produktionsmittel in der pflanzlichen und tierischen Erzeugung wiederverwertet werden. Gegenwärtig werden auch in der ökologischen Schweinehaltung vorwiegend Kraftfuttermittel eingesetzt. Ziel des Beitrags war die Ermittlung der Kosten bei einem erhöhten Anteil an Grundfuttermitteln in der Ration

Assessment of irregularities in organic imports from Ukraine to the EU in 2016, notified in OFIS

The underlying study of this report set out to improve the understanding situation concerning residues found in organic food products exported from Ukraine, and to formulate guidelines for identifying and reducing risks for contamination through non-permitted substances based on the results of an in-depth analysis of those residue cases notified in the European Commission’s Organic Farming Information System (OFIS) in 2016. Not surprisingly, the combination of various factors such as (i) the additional sampling required by the new EU import guidelines, (ii) the growing number of exported organic lots from Ukraine, and (iii) the improved analysis technology, led to an increased total number of cases of irregularities notified in OFIS in comparison to previous years. Nevertheless, the number of irregularities in Ukraine in 2016, notified in OFIS, is moderate (affecting estimated < 1% of all exported consignments from Ukraine). Of the lots affected, two thirds were ultimately released as “organic” after additional investigations had been carried out by the respective export CB. Yet, if analysis results of samples taken by the CB’s prior the export, i.e. from crops during the growing season and from lots before they are released for export are included in the risk assessment, Ukraine and its neighbouring countries do need to be considered as relatively high risk countries in terms of contamination and irregularities. It is further interesting to note that the likeliness of residue findings vary a lot among different CBs. The reasons why some CB’s have a high share of residue findings whereas for others proportionally much less residues are found are unclear and should be the subject of further assessments. One assumption is that some CBs took risk-oriented samples whereas others did not. Sampling during the production process (field/leafs and dust) effectively supports organic integrity. Most CB nevertheless focus on residue free final products. The way a CB responds on detected irregularities, i.e. investigates a case and derives “lessons learnt” is very important. A majority of OFIS cases from Ukrainian exports seems to be linked to insufficient management of handling procedure during the storage processes and the transport. However, drift on the field or the intentional use of unauthorised substances are also potential sources of irregularities related to exports from Ukraine. Apart from those cases for which likely root causes have been identified, no clear explanation for discrepancies between lab results between export and import countries could be found for nearly one third of the Ukrainian OFIS cases. Further investigations should be carried out to help identify the reasons for the relatively large differences between the lab results of samples taken from the same trade lots. It is important to better understand these discrepancies in sample measurements because these may lead to significant negative economic impacts for everyone involved in the value chain, even though no rules may have been broken. Another recommendation resulting from this study is to focus more on detecting potential contaminations on the field during the period of crop cultivation. Special attention should be given here to the testing of leaf sample of crops in which contamination has been detected in the past: rapeseeds, sunflower seeds or high quality milling wheat. CB’s should have guidelines on how and when leaf samples should be best taken. Ukrainian organic operators often complain that all Ukrainian operators are put in the same basket and treated as high-risk suppliers. In response to the stricter regulations imposed on them, operators and experts participating in the International Conference “Improving Integrity of Organic Supply Chains” in Odesa 2017 called for an amendment of the inspection policy. Instead of labelling entire countries as high-risk, focus should rather be placed on risky value chains. Supply chains considered high-risk should be relieved from extra measures, once they have demonstrated consistent compliance

Absence of long-range order in a spin-half Heisenberg antiferromagnet on the stacked kagome lattice

We study the ground state of a spin-half Heisenberg antiferromagnet on the stacked kagome lattice by using a spin-rotation-invariant Green's-function method. Since the pure two-dimensional kagome antiferromagnet is most likely a magnetically disordered quantum spin liquid, we investigate the question whether the coupling of kagome layers in a stacked three-dimensional system may lead to a magnetically ordered ground state. We present spin-spin correlation functions and correlation lengths. For comparison we apply also linear spin wave theory. Our results provide strong evidence that the system remains short-range ordered independent of the sign and the strength of the interlayer coupling

Regulation and function of tetrapyrrole biosynthesis in plants and algae

AbstractTetrapyrroles are macrocyclic molecules with various structural variants and multiple functions in Prokaryotes and Eukaryotes. Present knowledge about the metabolism of tetrapyrroles reflects the complex evolution of the pathway in different kingdoms of organisms, the complexity of structural and enzymatic variations of enzymatic steps, as well as a wide range of regulatory mechanisms, which ensure adequate synthesis of tetrapyrrole end-products at any time of development and environmental condition. This review intends to highlight new findings of research on tetrapyrrole biosynthesis in plants and algae. In the course of the heme and chlorophyll synthesis in these photosynthetic organisms, glutamate, one of the central and abundant metabolites, is converted into highly photoreactive tetrapyrrole intermediates. Thereby, several mechanisms of posttranslational control are thought to be essential for a tight regulation of each enzymatic step. Finally, we wish to discuss the potential role of tetrapyrroles in retrograde signaling and point out perspectives of the formation of macromolecular protein complexes in tetrapyrrole biosynthesis as an efficient mechanism to ensure a fine-tuned metabolic flow in the pathway. This article is part of a Special Issue entitled: Chloroplast Biogenesis

Das Konzept "Denken in Szenarien" als Methode der sicherheitspolitischen Analyse

Diese Dissertation beschäftigt sich mit Methoden langfristiger strategischer Analyse und strategischer Planung im Bereich der Sicherheitspolitik. Dazu werden zuerst jene Problemfelder betrachtet, die langfristige strategische Planung im Allgemeinen und im Kontext der Sicherheitspolitik im Speziellen erschweren. Dabei werden jene Kompetenzen herausgearbeitet, die jede Organisation, die in die Zukunft plant, bewältigen muss: 1) der Umgang mit Nichtwissen und 2) der Umgang mit Komplexität. Im Anschluss daran werden jene wissenschaftlichen und Konzepte dargestellt, die uns helfen, die o. a. Kompetenzen zu entwickeln und die Herausforderungen von strategischer Langfristplanung zu bewältigen. Dazu wird ein Überblick über die Zukunftsforschung und ihr umfangreiches methodisches Instrumentarium sowie über das Konzept des systemischen Denkens und systemtheoretische Ansätze gegeben. Szenarien stellen eine Synthese von zukunftsoffenem Denken (ein Hauptpostulat der Zukunftsforschung) und systemischem Denken dar und haben sich als ein zentrales methodisches Instrument der Zukunftsanalyse entwickelt. Das Konzept „Denken in Szenarien“ basiert auf der Erkenntnis, dass es aufgrund der zunehmenden Komplexität und Dynamik der Umfelder die Zukunft nicht geben kann, sondern dass vielmehr in alternativen möglichen Zukunftsbildern (Zukünften) gedacht werden muss. In diesem Zusammenhang wird sehr detailliert auf die unterschiedlichen Verfahren zur Erstellung dieser Szenarien eingegangen. Dabei werden sowohl induktiv-modellgestützte, aber auch deduktiv-intuitive Verfahren vorgestellt. Im Anschluss daran wird untersucht, wie diese Szenarien in das strategische Management von Organisationen eingebettet werden können. Darauf aufbauend wird ein szenariobasierter Prozess nationaler Sicherheitsplanung entworfen. Teil zwei dieser Arbeit stellt ein vereinfachtes Modell eines szenariobasierten Strategieentwicklungsprozesses in Form einer Fallstudie dar, in dem dieser o. a. Prozess am Beispiel der Entwicklung verteidigungspolitischer Handlungsoptionen eines Kleinstaats in der EU, basierend auf dem Konzept „Denken in Szenarien“, veranschaulicht wird

Annual report 2006 // Institute of Radiochemistry

[no abstract available

Annual Report 2010 - Institute of Radiochemistry

At the beginning of 2011, the former Forschungszentrum Dresden-Rossendorf (FZD) was fully integrated into the Helmholtz Association, as Helmholtz-Zentrum Dresden-Rossendorf (HZDR). Therefore, the present Annual Report 2010 of the Institute of Radiochemistry (IRC) is published as the first HZDR-Report. The Institute of Radiochemistry is one of the six Research Institutes of this centre. IRC contributes to the research program “Nuclear Safety Research” in the “Research Field of Energy” and performs basic and applied research in radiochemistry and radioecology. Motivation and background of our research are environmental processes relevant for the installation of nuclear waste repositories, for remediation of uranium mining and milling sites, and for radioactive contaminations caused by nuclear accidents and fallout. Because of their high radiotoxicity and long half-life the actinides are of special interest

DEM simulation of dense granular flows in a vane shear cell: Kinematics and rheological laws

The rheology of dense granular flows is investigated through discrete element method (DEM) simulation of a vane shear cell. From the simulation, profiles of shear stress, shear rate, and velocity are obtained, which demonstrates that the flow features in the vane shear cell are equivalent to those in the classic annular Couette cell. A novel correlation for the shear viscosity is formulated and leads to a new expression for μKT in the kinetic theory analysis. The μKT formulation is able to qualitatively capture the μ-I relation in the shear cell. A correlation length is added in the energy dissipation term to account for the effects of the particle motion correlation. A simplified correlation length model is derived based on DEM results and is compared with the literature. The modified granular kinetic energy equation is able to correctly predict the granular temperature profiles in the shear cell

The impact of a standardized vocal loading test on vocal fold oscillations

Introduction Vocal loading capacity is an important aspect of vocal health and is measured using standardized vocal loading tests. However, it remains unclear how vocal fold oscillation patterns are influenced by a standardized vocal loading task. Methods 21 (10 male, 11 female) vocally healthy subjects were analyzed concerning the dysphonia severity index (DSI) and high speed videolaryngoscopy (HSV) on the vowel /i/ at a comfortable pitch and loudness before and after a standardized vocal loading test (10 min standardized text reading, at a level higher than 80 dB (A) measured at 30 cm from the mouth). Results Changes in DSI were statistically significant, diminishing by 1.2 points after the vocal loading test, which was mainly caused by an increase of the minimum intensity. However, the pre-post comparison of HSV derived measures failed to show any statistically significant changes. Conclusion It seems necessary to analyze the effects of a standardized vocal loading test on vocal fold oscillation patterns with respect to softest phonation and phonation threshold pressure rather than comfortable pitch and loudness.Level of evidenc