Dynamic Enhancement of Nitric Oxide Radioluminescence with Nitrogen Purge

Remote detection of alpha radiation is commonly realised by collecting the light, the radioluminescence, that is produced when alpha particles are stopped in air. Radioluminescence of nitric oxide (NO) is primarily emitted between 200 nm and 300 nm, which makes it possible to use it for remote detection under daylight conditions. Quenching by ambient oxygen and water vapour, however, makes it generally difficult to effectively create NO radioluminescence. We present the detection of intense NO radioluminescence in ambient air under standard indoor lighting conditions using a nitrogen purge. The nitrogen contained NO impurities that were intrinsic to the gas and had not explicitly been added. We study the mechanisms that govern the NO radioluminescence production and introduce a model to describe the dynamics of the process. The level of NO contained in the gas was found to determine how successful a purge can be. We conclude by discussing possible applications of the technique in nitrogen-flushed gloveboxes at nuclear facilities where NO concentration of 100 ppb-1ppm would be sufficient for efficient optical alpha radiation detection in standard lighting conditions.Peer reviewe

Optical Stand-Off Detection of Alpha Radiation in Nuclear Facilities

Numerous nuclear power plants will soon reach the end of their lifetime and must be decommissioned. The number of upcoming decommissioning projects is unprecedented and new technologies are needed to rapidly and reliably identify radioactive contamination. Remote detection of alpha radiation by optical means is one of those new technologies. It collects the ultraviolet (UV) scintillation of nitrogen molecules (N2) in air, the radioluminescence, to reveal the presence of alpha emitters. This Thesis summarises the advances of the technology since its first conception and demonstrates its efficacy by remotely detecting alpha contamination in a nuclear research facility. It shows that alpha imaging requires the absence of daylight and that this limitation, together with lower-than-required sensitivity levels, make the technology mostly untenable for use in decommissioning tasks. Radioluminescence of nitric oxide (NO) is presented as a means to improve the sensitivity levels. It is shown that replacing the air around an alpha emitter with a mixture of 50ppm of NO in N2 amplifies the production of ultraviolet light by more than two orders of magnitude. The technique is shown to render the detection resistant to influences of daylight. A theory is developed that provides an explanation for the production of NO radioluminescence. The theory hypothesises that a specific form of fluorescence quenching and unique access to a reservoir of energy account for much of the light production. It is shown to correctly predict the conditions under which a N2 purge can create NO radioluminescence in otherwise ambient air. A fully resolved spectrum of the radioluminescence in water is presented. The origins of the radioluminescence are discussed and its utility for the remote detection of alpha radiation in liquids is highlighted. The Thesis outlines techniques that enable optical alpha detection to overcome both the daylight and the sensitivity problem. Limitations that keep the technology from finding widespread use in decommissioning tasks are directly addressed. The theory can be used to further enhance radioluminescence intensity

Indikatoren zur Ausbildung im Hochschulbereich : Studien zum Innovationssystem Deutschlands Nr. 10-2004

Im Berichtssystem zur technologischen Leistungsfähigkeit Deutschlands werden verschiedene Zugänge zum Thema gewählt. Die berichteten und bewerteten Indikatoren setzen bei der Produktion und der Anwendung von technischem Wissen an. Hierbei konzentriert sich die Berichterstattung zunächst aufdie „Input“- oder Entstehungsseite. Themenbereiche sind die Bildung von „Humankapital“ und die Wissenschaft, aber auch die industriellen Aktivitäten in Forschung und Entwicklung als unmittelbarete chnologiebezogene Anstrengungen der Wirtschaft. Die Ergebnisse dieser „Wissensproduktion“ („Outputindikatoren“) - an denen man messen kann, welche Beiträge für die gesamtwirtschaftlicheErfolgsbilanz zu erwarten sind - finden ihre Ausprägung in Innovationen, Patenten, Unternehmensgründungen sowie in den Marktergebnissen für die gesamte inländische Produktion und Nachfrage,für die Beschäftigung und im Außenhandel. Die technologische Leistungsfähigkeit einer Volkswirtschaft verändert sich nicht in kurzer Frist, sondern vielmehr über einen längeren Zeitraum hinweg. Insbesondere zeigen sich die Wirkungen von Veränderungen der technologischen Leistungsfähigkeit auf die Realisierung gesamtwirtschaftlicher Ziele (wie z. B. hoher Beschäftigungsstand, angemessenes Wirtschaftswachstum, Steigerung der Produktivität und Preisstabilität) nicht von heute auf morgen, sondern vielfach zeitlich stark verzögert. Entsprechend ist zur Beurteilung der technologischen Leistungsfähigkeit einer Volkswirtschaft eine längerfristige Betrachtungsweise geboten, die jedoch kontinuierlich zu wiederholen ist, um rechtzeitig auf eventuelle „Warnzeichen“ reagieren zu können. Diesem Grundkonzept zufolge werden in der Berichterstattung zur technologischen Leistungsfähigkeit Deutschlands die Indikatoren so konstruiert, dass mit ihrer Hilfe Zusammenhänge und Hintergründe der kurz-, mittel- und langfristigen Entwicklung betrachtet werden können. Eine wichtige Nebenbedingung für eine Berichterstattung wie diese ergibt sich aus dem - für einen „Monitor“ typischen - Charakter der periodischen Aktualisierbarkeit. Es ist von der Arbeitsgruppe ein System von Indikatoren entwickelt worden, das weitgehend auf bereits vorhandenen Daten und regelmäßig erstellten Statistiken und Analysen aufbaut. Das Indikatorensystem ist nicht auf umfangreiche eigenständige Sondererhebungen und -untersuchungen angewiesen, damit die Berichterstattung zur technologischen Leistungsfähigkeit Deutschlands kontinuierlich, in regelmäßigen Abständen und mit überschaubarem Aufwand aktualisiert und weiterentwickelt werden kann. Ein Grundprinzip gilt unabhängig von der Fristigkeit der Beobachtung: Die Interpretation der Messziffern ergibt sich immer aus einem Vergleich mit konkurrierenden Volkswirtschaften und aus ihrer zeitlichen Entwicklung

Alpha Radiation-Induced Luminescence by Am-241 in Aqueous Nitric Acid Solution

When exposed to air, alpha particles cause the production of light by exciting the molecules surrounding them. This light, the radioluminescence, is indicative of the presence of alpha radiation, thus allowing for the optical sensing of alpha radiation from distances larger than the few centimeters an alpha particle can travel in air. While the mechanics of radioluminescence in air and other gas compositions is relatively well understood, the same cannot be said about the radioluminescence properties of liquids. Better understanding of the radioluminescence properties of liquids is essential to design methods for the detection of radioactively contaminated liquids by optical means. In this article, we provide radioluminescence images of Am-241 dissolved in aqueous nitric acid solution and present the recorded radioluminescence spectrum with a maximum between, and a steep decrease at the short wavelength side of the maximum. The shape of the spectrum resembles a luminescence process rather than Cerenkov light, bremsstrahlung, or other mechanisms with broadband emission. We show that the amount of light produced is about 150 times smaller compared to that of the same amount of Am-241 in air. The light production in the liquid is evenly distributed throughout the sample volume with a slight increase on the surface of the liquid. The radioluminescence intensity is shown to scale linearly with the Am-241 concentration and not be affected by the HNO3 concentration.Peer reviewe

Indikatoren zur Ausbildung im Hochschulbereich: Studien zum Innovationssystem Deutschlands, Nr. 10-2004

--Deutschland,Hochschulbildung,Akademiker,Studienanfänger,Geschlecht,Arbeitsmarkt

Standoff UV-C imaging of alpha particle emitters

Alpha particles are proven to be very useful in many areas of medicine, technology and science. Yet, they represent the biggest risk to soft biological tissues compared to all nuclear decay products when ingested or inhaled, implying thus stringent radiation protection measures in the management and monitoring of samples that emit them. In this paper we present a standoff optical imaging approach that enables sensing of a radiological threat items at facilities where alpha-emitting material is manufactured, handled, used and stored, at safe distances without putting personnel at risk or contaminating equipment. The optical imaging of alpha-emitting samples is based on the radiation induced air luminescence (radioluminescence) in the UV-C (solar-blind) spectral region which enables detection of alpha particles even under bright light conditions. We show that by adding trace amounts of nitric oxide into the nitrogen atmosphere surrounding the sample, alpha sources with specific activities as low as 1.5 Bq/cm(2) can be remotely imaged. This work provides a proof-of-concept implementation of a novel imaging approach that not only enhances capabilities of a state to take actions which effectively mitigate consequences of an radiological emergency for the society, health, environment and economy, but also benefits nuclear industry in decommissioning efforts.Peer reviewe

Indikatoren zur Ausbildung im Hochschulbereich : Studie zum Innovationssystem Deutschlands Nr. 10-2003

Dieser Bericht wurde im Rahmen der erweiterten Berichterstattung zur technologischen Leistungsfähigkeit Deutschlands im Auftrag des Bundesministeriums für Bildung und Forschung erstellt

Indikatoren zur Ausbildung im Hochschulbereich: Studie zum Innovationssystem Deutschlands Nr. 10-2003

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What is a Macrophyte Patch? Patch Identification in Aquatic Ecosystems and Guidelines for Consistent Delineation

Schoelynck J, Creëlle S, Buis K, De Mulder T, Emsens W, Hein T, Meire D, Meire P, Okruszko T, Preiner S, Roldan Gonzalez R, Silinski A, Temmerman S, Troch P, Van Oyen T, Verschoren V, Visser F, Wang C, Wolters J, Folkard A, in press. . Ecohydrology & Hydrobiology. DOI 10.1016/j.ecohyd.2017.10.00

Expression profile of human Fc receptors in mucosal tissue: implications for antibody-dependent cellular effector functions targeting HIV-1 transmission

The majority of new Human Immunodeficiency Virus (HIV)-1 infections are acquired via sexual transmission at mucosal surfaces. Partial efficacy (31.2%) of the Thai RV144 HIV-1 vaccine trial has been correlated with Antibody-dependent Cellular Cytotoxicity (ADCC) mediated by non-neutralizing antibodies targeting the V1V2 region of the HIV-1 envelope. This has led to speculation that ADCC and other antibody-dependent cellular effector functions might provide an important defense against mucosal acquisition of HIV-1 infection. However, the ability of antibody-dependent cellular effector mechanisms to impact on early mucosal transmission events will depend on a variety of parameters including effector cell type, frequency, the class of Fc-Receptor (FcR) expressed, the number of FcR per cell and the glycoslyation pattern of the induced antibodies. In this study, we characterize and compare the frequency and phenotype of IgG (CD16 [FcγRIII], CD32 [FcγRII] and CD64 [FcγRI]) and IgA (CD89 [FcαR]) receptor expression on effector cells within male and female genital mucosal tissue, colorectal tissue and red blood cell-lysed whole blood. The frequency of FcR expression on CD14+ monocytic cells, myeloid dendritic cells and natural killer cells were similar across the three mucosal tissue compartments, but significantly lower when compared to the FcR expression profile of effector cells isolated from whole blood, with many cells negative for all FcRs. Of the three tissues tested, penile tissue had the highest percentage of FcR positive effector cells. Immunofluorescent staining was used to determine the location of CD14+, CD11c+ and CD56+ cells within the three mucosal tissues. We show that the majority of effector cells across the different mucosal locations reside within the subepithelial lamina propria. The potential implication of the observed FcR expression patterns on the effectiveness of FcR-dependent cellular effector functions to impact on the initial events in mucosal transmission and dissemination warrants further mechanistic studies