Thesis, Ph.D., University of Hong Kong, 1979. / Also available in print.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1968. / Typescript. Vita. Includes reprints of 2 articles by the author and others. Includes bibliographical references.

This work presents the development of a sub-micron nuclear microprobe for applications in the life sciences. It includes quantitative trace element analysis with sub-micron spatial resolution, 2D- and 3D-microscopy of density distributions and the targeted irradiation of living cells with counted single ions. The analytical methods base on particle induced X-ray emission spectrometry (PIXE), Rutherford backscattering spectrometry (RBS), scanning transmission ion microscopy (STIM) and STIM-tomography. The specific development of the existing nuclear microprobe LIPSION led to an improved performance of the capabilities for trace element analysis. For sub-micron analysis the spatial resolution could be improved to 300 nm at a sensitivity of about 1 µg/g for metal ions in biological matrices; for a resolution of 1 µm the sensitivity was improved to 200 ng/g (3 µmol/l). This habilitation thesis comprises a short general introduction including the motivation to utilize focussed high energy ion beams, an overview on the applications and actual research fields. The introduction is followed by the basic principles of the equipments and analytical methods. An estimation of the limits of resolution for element analytical and single ion techniques is given for the Leipzig system. Thereafter, selected studies from different research areas are presented. The first presented application is a study from environmental air pollution research. It is demonstrated that the microscopic elemental analysis of single aerosol particles can be used to assess the contributions from different sources. A further example is the analysis of the distribution of nanoparticles in skin cross-sections for a risk assessment of the applications of nanosized physical UV-filters in cosmetic products. The risk assessment is followed by the micro-analysis of trace elements, especially of bound metal ions, in brain sections on the cellular and sub-cellular level. After this the application of focussed MeV ion beams in low dose radiobiological research is presented. Finally, the analysis of 3D-density distributions by proton micro-tomography is demonstrated. A summary concludes on the applications and gives an outlook to further applications and methodological developments. The appendix comprises the relevant publications of the author. / Die vorliegende Arbeit etabliert für Anwendungen in den Lebenswissenschaften den Einsatz hochfokussierter MeV-Ionenstrahlen für nuklear-mikroskopische Methoden der quantitativen Spurenelementanalyse, der 2D- und 3D-Dichtemikroskopie sowie für die gezielte Bestrahlung einzelner lebender Zellen für radiobiologische Experimente. Zur Anwendung kamen die Methoden ortsaufgelöste Protonen induzierte Röntgenfluoreszenzanalyse (particle induced X-ray emission - PIXE), Spektrometrie rückgestreuter Ionen (Rutherford backscattering spectrometry - RBS) und Rastertransmissionsionenmikroskopie (scanning transmission ion microscopy - STIM). Durch eine gezielte Weiterentwicklung des bestehenden Ionenstrahlmikroskops, der Hochenergie Ionennanosonde LIPSION, konnte die Ortsauflösung für Spurenelementanalyse auf unter 300 nm verbessert werden, beziehungsweise die Sensitivität für Metallionen in biologischen Proben auf unter 200 ng/g (3 µmol/l) bei einer Ortsauflösung von 1 µm verbessert werden. Die Habilitationsschrift umfasst eine kurze allgemeine Einleitung einschließlich der Motivation für den Einsatz fokussierter MeV-Ionenstrahlen sowie einen Überblick über die Anwendungsgebiete und aktuellen Forschungsschwerpunkte. Danach werden kurz die Grundlagen der Technik und Methoden vorgestellt, gefolgt von einer Abschätzung der Auflösungsgrenzen für Elementanalysen und Einzelionentechniken. Danach werden ausgewählte Anwendungen aus verschiedenen Forschungsgebieten vorgestellt. Das erstes Beispiel ist aus der Umweltforschung. Es wird dargestellt, wie mittels ortsaufgelöster Elementspektroskopie eine Abschätzung der Feinstaubbelastung nach Beiträgen einzelner Verursacherquellen erfolgen kann. Dann folgt als Beispiel eine ortsaufgelöste Analyse der Verteilung von Nanopartikeln aus Sonnencremes in Hautquerschnitten zur Risikoabschätzung der Anwendungen von Nanotechnologie in kosmetischen Produkten. Desweiteren werden Studien der Spurenelementverteilung, speziell der von gebundenen Metallionen, in Hirnschnitten auf zellulärer und subzellulärer Ebene erläutert. Das anschließende Beispiel erläutert die Anwendung niedriger Energiedosen in der Radiobiologie anhand des Beschusses einzelner lebender Zellen mit abgezählten einzelnen Ionen. Als letztes Beispiel wird die Anwendung hochfokussierter Ionenstrahlen für die Mikrotomographie gezeigt. Abschließend folgt eine zusammenfassende Bewertung der vorgestellten Anwendungen mit einem Ausblick auf weitere Anwendungen und methodische Entwicklungen. Der Arbeit sind die relevanten Veröffentlichungen mit Beteiligung des Autors als Anhang beigefügt.

No description available.

Thesis advisor: Yvette D. Kuiper / The Paleoproterozoic Foxe Fold Belt (FFB) is composed of the Penrhyn Group, a Paleoproterozoic passive margin sequence, and supracrustal Archean basement. These units were interfolded and metamorphosed at amphibolite to lower granulite facies conditions during the 1883-1865 Ma Foxe orogeny, a part of the Trans-Hudson orogeny. The purpose of this study was to constrain the timing of metamorphism and deformation within the Penrhyn Group, in order to determine the role of the Foxe orogeny within the Trans-Hudson orogeny. Petrographic analysis, P-T-X pseudosections, monazite composition, and in-situ electron microprobe U-Th-Pb geochronology from sampled metapelites were used to determine the age and significance of metamorphic and deformation events related to monazite age populations. Population 1 is composed of 1926 ± 8 Ma monazite interpreted as detrital. Population 2 consists of 1892 ± 9 Ma monazite, the youngest detrital ages seen in the Penrhyn Group. Population 3 is composed of 1853 ± 5 Ma high-Y + HREE monazite predating an episode of pervasive garnet growth. Population 4 contains 1839 ± 8 Ma lower-Y + HREE monazite related to pervasive garnet growth. Population 5 is 1819 ± 16 Ma lowest-Y + HREE monazite with high LREE and Th/U, linked to the interpreted peak reaction: Bt + Sil + Pl = Grt + Crd + Kfs + melt. Monazite constraints on deformation fabrics indicate that deformation was ongoing locally as early as 1853 ± 9 Ma and continued until at least 1814 ± 14 Ma, pre- to syn-peak metamorphism. Rare 1794-1776 Ma monazite is interpreted to constrain the age of retrograde metamorphism as the Trans-Hudson orogeny waned. These data support interpreted clockwise P-T-t-D paths consistent with metamorphism initiated by crustal thickening in an orogenic belt. / Thesis (MS) — Boston College, 2013. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Earth and Environmental Sciences.

Thesis (Ph. D.)--Michigan State University. Electrical Engineering, 2008. / Title from PDF t.p. (Proquest, viewed on Aug. 17, 2009) Includes bibliographical references (p. 120-135). Also issued in print.

Thesis (DTech (Science))--Peninsula Technikon, Cape Town, 2003. / The impetus for the refinement and renewal of daily-used products has spurred international interest in investigating the small in homogeneities that might exist in these products. This interest has become an important part in the design philosophy, which is based on structural information gained by the analysis of these products. It is this drive that initiated the study to investigate the simultaneous use of novel nuclear analytical techniques such as micro proton induced X-ray emission( u-PlXE), micro proton induced gamma-ray emission (u-PlGE) and micro proton backscattering (u-RBS) to achieved a broader and yet deeper insight into the fine structure of products. The fundamental underlying physical principles of these techniques are discussed to gain in-depth knowledge on how to them to obtain the desired information. Also determined was the degree of accuracy that could be attained in the application of this knowledge. These principles were evaluated in conjunction with the instrumentation with which the applicability of these techniques could then be further extended. More so is the use of sophisticated software that facilitated the use of both physical and instrumental parameters. After describing the necessary implements to achieve this further know-how, products of industrial origin were investigated to determine in homogeneities that existed in those products and compared those theoretical values. The first application was made to ceramic-based sorption electrodes to be used in the purification of wastewater.

This work describes an extension of the Microprobe functionality for detection and filtering of application protocols. The Microprobe is an embedded system designed for monitoring network links at speed 1 Gb/s without loosing any packets. The detection of application protocols requires using of computationally expensive operations, especially string lookup (usually based on regular expressions). Based on the study of several protocols (SMTP, POP3, FTP, SIP) a draft of a new architecture has been created. The new architecture splits this functionality between programmable logic FPGA and processor. The FPGA performs preprocessing of network traffic consisting of a lookup for user identifiers and protocol-specific patterns. The processor verifies that it is the requested communication. The processor does not need to process the entire network traffic but only the part pre-filtered in the FPGA. The software part is extended by a module for the analysis of SMTP which allows processing of more than 5,000 network flows per second. Support for other protocols can be added by an extension of the software part.

Antibody-coated microprobes were used to determine whether immunoreactive enkephalins were released in response to fatiguing isometric contractions of the hind-limb muscles in cats anesthetized with α-chloralose. Contractions were performed by stimulating the tibial nerve via a microprocessor-controlled stimulator. Microprobes were inserted into the periaqueductal grey (P 0.5-1.0 mm) prior to, during and following fatiguing contractions. During fatiguing contractions, mean arterial blood pressure increased by 76 ± 9 mmHg above resting and recovery levels. Levels of immunoreactive enkephalins were elevated in the dorsolateral periaqueductal grey during the isometric contraction when compared to resting levels. It is possible that isometric muscle contraction causes the release of Met-enkephalin-like substances in the periaqueductal grey.

Antibody microprobes were used to study release of immunoreactive neurokinins in the dorsal horn of the anaesthetized spinal cat following sustained isometric contraction of ipsilateral hindlimb muscles. Microprobes had immobilized antibodies to neurokinin A (NKA) on their outer surfaces and bound a proportion of released molecules when inserted in the central nervous system. Bound molecules were detected in autoradiographs as zones of reduced binding of 125I-NKA in which microprobes were incubated after withdrawal from the spinal cord. The left hindlimb was immobilized using an epoxy bandage splint and isometric contraction of muscles induced by intermittent tetanic stimulation of a ventral root. A basal presence of immunoreactive neurokinins was detected and this was increased by sustained isometric muscle contraction. It is probable that ergoreceptors contain and release neurokinins.