Radioactiviteit in gras: situatie in Nederland, september 2007

Bij een nucleaire calamiteit is gras één van de matrices die als eerste wordt onderzocht op een mogelijke radioactieve besmetting. Eenmaal per jaar wordt de operators van het LMRV (Landelijk Meetnet Radioactiviteit in Voedsel) verzocht om, naast hun reguliere werk, een grasmonster te analyseren volgens de voorgeschreven procedure.. Dit onderzoek beperkte zich tot de monstername en de analyse van gras. Uit de analyseresultaten, die op het RIKILT worden geïnterpreteerd en gevalideerd, kan worden opgemaakt hoe groot de eventuele besmetting is (gewees

Technetium in tomato-plants: Approaches, accumulation and metabolism

Applied Science

Radioactiviteit in gras: situatie in Nederland, september 2007

Bij een nucleaire calamiteit is gras één van de matrices die als eerste wordt onderzocht op een mogelijke radioactieve besmetting. Eenmaal per jaar wordt de operators van het LMRV (Landelijk Meetnet Radioactiviteit in Voedsel) verzocht om, naast hun reguliere werk, een grasmonster te analyseren volgens de voorgeschreven procedure.. Dit onderzoek beperkte zich tot de monstername en de analyse van gras. Uit de analyseresultaten, die op het RIKILT worden geïnterpreteerd en gevalideerd, kan worden opgemaakt hoe groot de eventuele besmetting is (gewees

Targeted multifunctional lipid-based nanocarriers for image-guided drug delivery

Lipid-based nanocarriers have proven successful in the delivery of mainly chemotherapeutic agents, and currently they are being applied clinically in the treatment of various types of cancer. These drug delivery systems achieve increased therapeutic efficacy by altering the pharmacokinetics and biodistribution of encapsulated drugs, resulting in decreased drug toxicity and enhanced accumulation in tumor tissue. This increased accumulation is due to the relatively leaky immature vasculature of a tumor. After the clinical relevance of such drug delivery systems was demonstrated, research in this area focused on optimization, both by cell specific targeting and including controlled and triggered release concepts within the carrier. These more advanced targeted nanocarriers in general have clearly shown their potential in various animal tumor models and await clinical application. The development of targeted nanocarriers in which therapeutic and imaging agents are merged into a single carrier will certainly be of importance in the near future. Indeed, scientists active in the field of imaging (e.g. nuclear and magnetic resonance imaging) have already started to exploit nanocarriers for molecular imaging. Image-guided drug delivery using these multifunctional nanocarriers, containing therapeutic and imaging agents, will ultimately allow for online monitoring of tumor location, tumor targeting levels, intratumoral localization and drug release kinetics prior and during radio- and/or chemotherapeutic treatment. This review describes the current status and challenges in the field of nanocarrier-aided drug delivery and drug targeting and discusses the opportunities of combining imaging probes with these drug carriers and the potential of these multifunctional lipid-based nanocarriers within image-guided drug delivery

On the separation of 99mTcO4-, 99mTc-DTPA and 99mTc-citrate as marker species for the determination of Tc chemical forms in plant material using capillary zone electrophoresis

The present paper addresses the potential use of capillary zone electrophoresis (CZE) as an anal. tool in 99Tc speciation studies. To optimize sampling, storage and anal. procedures, the three marker compds. 99mTcO4-, 99mTc-DTPA and 99mTc-citrate were synthesized and used in test-measurements with CZE. The results underline the superior sepn. power of the CZE technique, and indicate good CZE performance for the stable 99mTcO4- and 99mTc-DTPA compds. The data suggest that CZE may be used without problems for various Tc-compds. of intermediate mobilities. The specific data of 99mTc-citrate suggest that with this marker compd. a threshold lability is reached for the use of CZE in plant Tc-speciation studies. This result means that CZE cannot be used in analyses of Tc-compds. which are less stable than Tc-citrate. Future CZE work will comprise the synthesis and use of Tc-markers of intermediate mobilities and stabilities; furthermore, effects of marker matrixes and the plant matrix on CZE performance will be investigated. [on SciFinder (R)

Landelijk meetnet radioactiviteit in voedsel : grasmetingen in de periode september 2010 tot en met oktober 2011

LMRV (Landelijk Meetnet Radioactiviteit in Voedsel) is een onderdeel van het Nationaal Plan Kernongevallenbestrijding (NPK) en beschikt over voedselmonitoren die zijn voorzien van natriumjodide detectoren waarmee gamma-emitters kunnen worden aangetoond. Gras is een belangrijke matrix die kort na een nucleair of radiologisch ongeval als eerste wordt onderzocht op een mogelijke radioactieve besmetting als gevolg van depositie

On the separation of 99mTcO4-, 99mTc-DTPA and 99mTc-citrate as marker species for the determination of Tc chemical forms in plant material using capillary zone electrophoresis

The present paper addresses the potential use of capillary zone electrophoresis (CZE) as an analytical tool in 99- technetium speciation studies. In order to optimise sampling, storage and analytical procedures, the three marker compounds 99mTcO4-, 99mTc-DTPA and 99mTc-citrate were synthesised and used in test-measurements with CZE. The results underline the superior separation power of the CZE technique, and indicate good CZE performance for the stable 99mTcO4- and 99mTc-DTPA compounds. The data suggest that CZE may be used without problems for various Tc-compounds of intermediate mobilities. The specific data of 99mTc-citrate suggest that with this marker compound a threshold lability is reached for the use of CZE in plant Tc-speciation studies. This result means that CZE cannot be used in analyses of Tc-compounds which are less stable than Tc-citrate. Future CZE work will comprise the synthesis and use of Tc-markers of intermediate mobilities and stabilities; furthermore, effects of marker matrices and the plant matrix on CZE performance will be investigated.Applied Science

On the Beneficial Role of Silicon to Organisms: A Case Study on the Importance of Silicon Chemistry to Metal Accumulation in Yeast

Silicon is involved in numerous important structural and functional roles in a wide range of organisms, including diatoms, plants, and humans, but clear mechanisms have been discovered only in diatoms and sponges. Silicate availability influences metal concentrations within various cell- and tissue-types, but a mechanism has not been discovered so far. In an earlier study on Baker’s yeast Saccharomyces cerevisiae it was proposed that a chemical mechanism, rather than a biological one, is important. In the present study, the interaction of silicon with Baker’s yeast is further investigated by studying the influence of zinc and magnesium on Si accumulation both at a low and a high silicate concentration in the medium. Si accumulation fitted well with Freundlich adsorption and Si release followed depolymerization kinetics, indicating that silicate adsorbs to the surface of the cell rather than being transported over the cell membrane. Subsequently, adsorbed silicate interacts with metal ions and, therefore, alters the cell’s affinity for these ions. Since several metals are nutritional, these Si interactions can significantly change the growth and viability of organisms. In conclusion, the results show that chemistry is important in Si and metal accumulation in Baker’s yeast, and suggest that similar mechanisms should be studied in detail in other organisms to unravel essential roles of Si.Radiation, Radionuclides and ReactorsApplied Science

Rapid screening methods for beta-emitters in food samples

In case of a nuclear emergency, many samples need to be measured in a short time period. Therefore, it is of vital importance to have a quick and reliable (screening)method. Most methods to determine total beta activity are time-consuming because of extensive sample preparation, such as ashing.In this article three different rapid screening methods for beta emitting nuclides in agriculture, livestock and fishery products were tested and compared to each other, and to an accurate but more time consuming reference method. The goal was to find the method with the optimal trade-off between accuracy, speed and minimal detectable activity (MDA). All of the methods rely on liquid scintillation counting (LSC) or Cerenkov counting, and differ mainly in sample preparation.For matrices with little or no colour, the direct LSC-method is the most accurate and fastest option, while for darker coloured samples this method is not suitable because of high colour quenching. For such samples, two additional methods using a microwave digestion during sample preparation, produced good results.</p