761 research outputs found
A calibration procedure for a traceable contamination analysis on medical devices by combined X-ray spectrometry and ambient spectroscopic techniques
No full textThere is a strong need in the medical device industry to decrease failure rates of biomedical devices by reducing the incidence of defect structures and contaminants during the production process. The detection and identification of defect structures and contaminants is crucial for many industrial applications. The present study exploits reference-free X-ray fluorescence (XRF) analysis as an analytical tool for the traceable characterization of surface contaminants of medical devices, in particular N,N'-ethylene-bis (stearamide), an ubiquitous compound used in many industrial applications as a release agent or friction reduction additive. Reference-free XRF analysis as primary method has been proven to be capable of underpinning all other applied methods since it yields the absolute mass deposition of the selected N,N'-ethylene-bis (stearamide) contaminant whilst X-ray absorption fine structure analysis determines the chemical species. Ambient vibrational spectroscopy and mass spectroscopy methodologies such as Fourier transform infrared, Raman, and secondary ion mass spectroscopy have been used in this systematic procedure providing an extensive range of complementary analyses. The calibration procedure described in this paper was developed using specially designed and fabricated model systems varying in thickness and substrate material. Furthermore, typical real medical devices such as both a polyethylene hip liner and a silver-coated wound dressing have been contaminated and investigated by these diverse methods, enabling testing of this developed procedure. These well-characterized samples may be used as calibration standards for bench top instrumentation from the perspective of providing traceable analysis of biomaterials and surface treatments. These findings demonstrate the potential importance and usefulness of combining complementary methods for a better understanding of the relevant organic materials
Faculty Spotlight 2008-09 Richard Herrmann
No full textMershon Center for International Security Studies Faculty Spotlight 2008-09The University Archives has determined that this item is of continuing value to OSU's history.Richard Herrmann is director of the Mershon Center for International
Security Studies. Since 2002, he has led the center's efforts to attract a
world-class faculty, establish its reputation as a leader in security studies,
and offer special opportunities to enhance the student experience.
Herrmann specializes in international relations, security and conflict
studies, political psychology, and politics in the Middle East and Russia.
He has written on the role of perception and imagery in foreign policy and
the importance of nationalism and identity politics. He is the author or
editor of three books and more than 40 articles in such journals as
American Political Science Review, International Organization,
International Security, and World Politics
Quantitative elemental analysis of ambient aerosol particles using portable TXRF
No full textA reliable analysis of aerosol particle is curial for enforcing EU air quality regulations to protect human health, and for research on climate change effects [1]. Although metrics such as PM10 and PM2.5 are currently in use, the level of uncertainty of aerosol metrics is too high and the traceability is insufficient. Within the AEROMET project [2] procedures are developed aiming at reducing the uncertainties of particle mass, size, and number concentration measurements including the characterization of regulated components in airborne particles. Here, we present an approach how to improve the uncertainties of the particle mass by mobile total reflection x-ray fluorescence (TXRF) analysis. The combination of TXRF and aerosols sampling techniques supported by reference-free synchrotron radiation-based XRF enables a quantitative real-time analysis of particle mass. During in-field campaigns, the procedure was tested, monitoring the size dependent mass concentrations of specific elements in ambient aerosols under dynamic conditions. This approach allows a direct time and size-resolved analysis without laborious digestion steps and a reduced risk of contamination.
Aerosol particles were sampled in a 13-stage DLPI impactor on acrylic discs. TXRF analysis was performed on-site with the transportable spectrometer S2 PICOFOX (Bruker Nano GmbH). The TXRF quantification was based on internal standardization. At moderate air pollution levels (PM10 20 µg/m³) sampling times of less than 2 hours were enough to detect elements in different particle size bins. The on-site approach and the high sensitivity of TXRF enables the observation of rather quick changes in the quantity and distribution of elements in an ambient aerosol on the day of sampling. The analysis of the morning and afternoon sampling shifts reveals the occurrence of the elements Fe, Ca and Si in different size bins as well as their temporal change in respective mass concentrations over the day while the distributions of several other elements remain unchanged
Quantification of element mass concentrations in aerosols by combination of cascade impactor sampling and in-situ TXRF Spectroscopy
No full textA mobile Bruker S2 Picofox TXRF spectrometer has been used in two field campaigns within the EMPIR env07 AEROMET project for the on-site analysis of cascade impactor aerosol samples.The results show that even at moderate air pollution levels – i.e.PM10 fairly below 20 μg/m³ - element mass concentrations in air in the range of 100 pg/m³could be measured in up to 13 size bins after sampling times of less than only 0.5 days
A methodological inter-comparison study on the detection of surface contaminant sodium dodecyl sulfate applying ambient- and vacuum-based techniques
No full textHenri Temianka Correspondence; (herrmann)
No full textThis collection contains material pertaining to the life, career, and activities of Henri Temianka, violin virtuoso, conductor, music teacher, and author. Materials include correspondence, concert programs and flyers, music scores, photographs, and books.https://digitalcommons.chapman.edu/temianka_correspondence/3597/thumbnail.jp
Henri Temianka Correspondence; (herrmann)
No full textThis collection contains material pertaining to the life, career, and activities of Henri Temianka, violin virtuoso, conductor, music teacher, and author. Materials include correspondence, concert programs and flyers, music scores, photographs, and books.https://digitalcommons.chapman.edu/temianka_correspondence/3594/thumbnail.jp
Entwicklung und Validierung der Methode GIXRF NEXAFS zur Analyse von tief vergrabenen Nanoschichtsystemen
No full textDevelopment and validation of the methodology GIXRF-NEXAFS for the analysis of deeply buried nano-layered systems
No full textIm Rahmen dieser Arbeit ist eine zerstörungsfreie und nicht-präparative Analysemethode entwickelt worden, die es ermöglicht den chemischen Bindungszustand von vergrabenen Nanoschichten in Abhängigkeit von der Probentiefe zu bestimmen. Dazu wurde eine Ansatz gewählt, der zwei wohl bekannte Methoden miteinander kombiniert, nämlich die Röntgenfluoreszenzanalyse unter streifendem Einfall (GIXRF) und die Nahkantenröntgenabsorptions-spektroskopie (NEXAFS). Das Augenmerk bei der Entwicklung der kombinierten Methode lag auf der Analyse von Nanoschichtsystemen, wie sie bei funktionellen Nanomaterialien Anwendung finden. Dies ist von Bedeutung, da derartige Nanomaterialien zunehmend komplexer werden, so dass eine Betrachtung der Oberflächeneigenschaften nicht mehr hinreichend gut das Gesamtsystem erklärt. Die durch Nano- und Grenzschichten bedingten Materialeigenschaften sind nicht mehr vernachlässigbar und müssen zuverlässig erfasst werden. Eine zerstörungsfreie Analyse der Materialeigenschaften eines solch komplexen Systems kann nur stattfinden, wenn die Informationstiefe des Charakterisierungsverfahrens entsprechend variabel angepasst werden kann. Die GIXRF-Methode ist sensitiv für den Bereich von einigen wenigen bis einigen hundert Nanometern Tiefe. Sie ist charakterisiert durch Einfallswinkel, die bis zu einem Vielfachen des kritischen Winkels der Totalreflexion groß sind und durch Interferenzeffekte der einfallenden und der reflektierten Strahlung, die sowohl im Nanoschichtsystem als auch oberhalb dessen Oberfläche auftreten. Diese Interferenzeffekte werden auch als stehendes Wellenfeld oder X-ray standing Wave - XSW bezeichnet. Hochauflösende Röntgenabsorptionsspektroskopie wie NEXAFS ermöglicht es aufgrund der spezifischen Nahkantenstruktur auf den Bindungszustand des untersuchten Elementes zu schließen. Da bei der Kombination von GIXRF und NEXAFS die einfallende Photonenenergie über einen vorgewählten Bereich variiert wird, ändern sich dabei auch die Anregungsbedingungen in der zu untersuchenden Schicht. Der Einfallswinkel muss deshalb so angepasst werden, dass sich die jeweiligen Anregungsbedingungen nicht wesentlich ändern. Um dies experimentell zuverlässig erreichen zu können, muss darauf geachtet werden, dass eines der Intensitätsmaxima oder aber eine ähnliche Struktur des stehenden Wellenfeldes in der zu untersuchenden Tiefe lokalisiert bleibt. Die hierfür erforderlichen Einfallswinkel müssen basierend auf XSW-Rechnungen im Vorfeld bestimmt werden. Dafür wurde eigens ein Programm für Vielfachschichtsysteme entwickelt und implementiert, das auf der makroskopischen optischen Theorie beruht. Des Weiteren wurden optische Konstanten, die für die Berechnung der XSW- Intensität benötigt werden, mittels Röntgenreflektometrie bestimmt. Für die methodische Entwicklung wurden tief vergrabene Titanschichten in jeweils unterschiedlichem Oxidationszustand verwendet. "Tief vergraben" bedeutet hier, dass die Dicke der Deckschicht größer ist als die Informationstiefe von niederenergetischen Elektronen. Um das Potential dieser Methode zu illustrieren, wurden Titan/Titanoxid Doppelschichtsysteme tiefensensitiv bezüglich der chemischen Spezies untersucht. Die Modellierungen der Intensitätsverteilung des XSW-Feldes der Doppelschichten haben gezeigt, dass eine Differenzmethodik der vielversprechendste Ansatz ist. Dazu wurde ein entsprechendes Konzept erarbeitet und validiert. Es konnte gezeigt werden, dass ein Speziationstiefenprofil zerstörungsfrei im weichen Röntgenbereich erstellt werden kann und zu vielversprechenden Ergebnissen führt. Darüber hinaus konnten auch die Grenzen der Sensitivität dieser Methodik für einzelne Probensysteme ermittelt werden.This work focuses on the development of a non-destructive and non-preparative analysis method, which allows for the analysis of the chemical species of nano-layered samples depending on the depth. For this purpose, two well-known methods have been combined, namely X-ray fluorescence analysis under grazing incidence conditions (GIXRF) and Near Edge X-ray Absorption Fine Structure spectroscopy (NEXAFS). Special attention was paid to the analysis of nano-layered systems, like it is the case for functional nanomaterials. This is of importance, because such kind of materials become more and more complex and there is a transition from surface to interface structures. In particular, nanolayers and interfaces have a strong influence on the material properties and their influence can not be neglected, when aiming at a full understanding of the relation between functionality and chemical or physical properties. A non-destructive analysis of the material properties of such complex structures can only accomplished, when the information depth is variably tunable. The GIXRF method is sensitive in the depth range from a few to several hundred of nanometers. It is characterized by angles of incidence ranging from the critical angle of internal total reflection to multiples of it. In the grazing incidence regime interference effects occur at and below the surface, when both the incident and the reflected beam are interfering. This interference effects are also called X-ray standing wave field (XSW). High resolution X-ray absorption spectroscopy like NEXAFS allows for the determination of the chemical binding state of the element from the specific near edge fine structure. By combining GIXRF and NEXAFS, the incident photon energy is varied in a pre-selected range, and as a consequence the excitation conditions in the layer of interest are changing as well. For this reason, the angle of incidence has to be adapted in such a way that the excitation conditions remain constant, when the incident photon energy is varied. For a reliable experimental realization this means that one of the anti-nodes or a similar structure of the X-ray standing wave field has to be localized in the depth range of interest. For this reason, the necessary angles of incidence have to be previously determined based on XSW intensity calculations. Therefore, own software for multi-layered structures was developed and implemented, which rely on macroscopic optical theory. In addition, relevant optical constants were experimentally determined by means of X-Ray reflectometry (XRR). For the methodological development, deeply buried titanium layers in different chemical binding states were investigated. Differently oxidized titanium layers were deposited with an ion beam sputtering deposition technique. "Deeply buried" means, that the thickness of the cap layer is larger than the information depth of low energy photoelectrons. To demonstrate the full potential of the method, a species depth profile was derived for double layer systems consisting of two titanium layers in different chemical binding state. The modeling of the XSW intensity distribution illustrates that a differential methodology is the most promising approach for this challenge. A corresponding concept was developed, applied and validated. The results confirm the potential of a non-destructive species depth profiling in the soft X-ray range. Moreover, the results are rather promising. Furthermore, the limits of sensitivity of this method could be derived for some sample configurations
AEROMET – Traceable and reliable chemical analysis of aerosols by X-ray spectrometry
No full textTraceable and reliable chemical element analysis of aerosols by X-ray spectrometry was investigated using aerosol samples from field campaigns which have been measured in the GIXRF-beamline at BESSY.
The reference-free XRF approach allows for a traceable analysis of the mass deposition.
Traceable quantification by means of XRF can be transfered to benchtop instrumentation used in the laboratory Chemical and dimensional analysis of deposited aerosol allows for a comprehensive analysis of aerosols, e.g. for toxicity assessment and determination of the source The folowing elements could be identified and quantified in the field samples: Al, Si, P, S, Cl, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Br, Rb, Sr, Y, W, Pb
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