Faseroptische Dosimeter fuer die in-vivo Dosimetrie Ergebnisse des BMBF-Verbundprojekts Glasfasersensorik in Medizin. Teilprojekt: Faseroptisches Dosimeter FADOS

Lichtwellenleiter, die fuer Gamma- und Elektronenstrahlung empfindlich sind, koennen zur lokalen on-line Dosisbestimmung waehrend der Strahlentherapie eingesetzt werden. Die Eigenschaften von Lichtwellenleitern (u.a. kleine geometrische Abmessungen, Flexibilitaet, Gewebevertraeglichkeit) und die rein optische Signalentstehung und -uebertragung erlauben einen intrakorporalen Einsatz von faseroptischen Dosimetern mit minimaler Belastung des Patienten. Sie erlauben eine on-line Dosisbestimmung im Tumor selbst oder im umliegenden gesunden Gewebe. Eine sichere Dosisbestimmung zur Kontrolle und Verifizierung der Bestrahlungsplanung schon waehrend der Bestrahlung kann zu einer erheblichen Verbesserung der Therapie und damit der Tumorkontrolle beitragen. Es werden die dosimetrischen Eigenschaften ausgewaehlter Lichtwellenleiter untersucht, unterschiedliche Sensortypen beschrieben und ihre Anwendungsmoeglichkeiten in der Strahlentherapie aufgezeigt. On-line-Auswerteverfahren zur Korrektur der auftretenden Fadingeffekte und zur Kompensation der Abweichung der Dosisanzeige von der Gewebeaequivalenz werden mitgeteilt. Erste klinische Anwendungen einiger Sensortypen werden beschrieben. (orig.)Optical fibers, sensitive to gamma- and electron-radiation, can be used for local on-line dose measurements during radiation therapy. The properties of optical fibers such as small dimensions, high flexibility and biocompatibility as well as the pure optical signal generation and transfer enable an intracorporal application of these dosimeters with minimal burden to the patient. They allow an on-line measurement in the tumor itself or in the surrounding tissue. A good dose determination already during the irradiations for control and verification of irradiation planning will give a considerable improvement of the therapy and so also a good tumor control. The properties of selected optical fibers for dosimetric purposes have been investigated. Different sensor types and their applications in radiotherapy are described. On-line evaluation procedures for fading and tissue-equivalence corrections of the dose reading are also described in detail. First clinical tests with the dosimeter are being discussed. (orig.)SIGLEAvailable from TIB Hannover: RA 831(3249) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany); Duisburg Univ. (Gesamthochschule) (Germany); Procom Ingenieurunternehmen fuer Computergestuetzte Produkte G.m.b.H., Aachen (Germany); VYGON-Erzeugnisse fuer Medizin und Chirurgie-GmbH und Co. KG, Aachen (Germany)DEGerman

Neue Katalysatoren fuer ein umweltschonendes Verfahren zur loesungsmittelfreien Herstellung von Synthesekautschuk. Teilprojekt: Katalysator-Charakterisierung Schlussbericht

1. Techniques of gaseous polymerisation of butadiene are not yet realized in the chemical industry. The substitution of world-wide applied techniques of polymerisation in solvents with aid of Ziegler-Natta-catalysts based on Titanium, Cobalt, Nickel, and Neodynium will result in saving of expense and in technical and environmental safety by gaseous polymerisation. 2. Firstly this coordinated project of research is an attempt to develop such a kind of catalysts by supporting of Neodymium-Organyls of Silicagels forming so called 'single site' catalysts to compare technical to modelling and also homogeneous to heterogeneous catalysis. In this part we have investigated the structures, chemical bondings and reactivities of unsupported and supported compounds of Neodymium and Lanthanum to form complex catalysts. 3. The applications of surface chemical analysis (TPRS) and vibrational spectroscopy (DRIFTS) are crowned with success, but the application of electronic spectroscopy (UV/VIS) proved to be unsuccessfully. 4. The structures and reactivities of the Allyl groups of the complexes and their products of thermic decomposition and chemical reactions (Allenylidene, Hydrido) were investigated. Our Identifications and interpretations were done with the aid of new methods of computing vibrational spectra. 5. Our results will help to understand the new catalysts for gaseous polymerisation of butadiene. Our developed analytical methods are appropriate to product and quality control in catalysts' production. (orig.)SIGLEAvailable from TIB Hannover: F97B2395+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

The gas phase acidity of oligofluorobenzenes and oligochlorobenzenes: about the additivity or non-additivity of substituent effects

The deprotonation energies of benzene, fluorobenzene, all di-, tri-, and tetrafluorobenzenes, pentafluorobenzene, chlorobenzene, all di-, tri-, and tetrachlorobenzenes, and pentachlorobenzene have been calcd. at various levels of second-order Moller-Plesset and d. functional theory. Taking the previously detd. exptl. data as a benchmark, good agreement was achieved in the chloro series even with moderate computational effort, whereas more extended basis sets have to be used to obtain meaningful nos. in the fluoro series. Apparently, most extensive electron correlation is required to avoid artifacts caused by the proximity of non-bonding lone pairs at the carbanionic center and at the fluorine atoms. When two or more fluorine substituents were introduced in the same arom. ring, their individual effects (as defined by position-dependent acidity increments) proved to be perfectly additive in the entire series. In contrast, the acidifying effect of chloro substituents was found to level off when the no. of such halogens increases. Additivity or non-additivity of element effects cannot be ascertained after having merely compared the acidity of mono- and disubstituted substrates, but only after having moved to higher degrees of substitution. [on SciFinder (R)

Lokales rechnergestuetztes Ueberwachungssystem fuer den THTR-300

SIGLEDEGerman