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By 1991 a new plant for management of radioactive waste will be erected in the CINR. Thus increased atomic safety and radiation protection will be attained, the economy of waste management and the quality of the conditioned waste will simultaneously be improved. Facilities for volume reduction (evaporation, press compaction, solidification) and conditioning (solidification, packing) will be available for the treatment of radioactive waste. A novel handling technique will ensure safe handling of radioactive waste conditioned for repository. The facilities mentioned above will be installed in a building of about 25000 m3.

Follicles were examined with the scanning electron microscope (SEM) following preparation of cryofractured specimens of rat ovaries. After perfusion fixation with 2.5% glutaraldehyde buffered at pH 7.4 with 0.1M cacodylate, ovaries were trimmed of fat and decapsulated, fixed for an additional 12 hours, washed in distilled H2O for 20 hours and postfixed in 1% OsO4 in distilled H2O for 30 minutes. Following a brief wash, ovaries were dehydrated in a linear gradient of dist. H2O/ethanol, frozen in Freon 22, cryofractured under liquid nitrogen, brought to 1 degree C in ethanol, and critical point dried from CO2. Follicles cleaved through their oocytes were examined with SEM to determine the ultrastructural characteristics of developing and atretic follicles revealed by cryofracture. Cytoplasmic arrays of parallel sheets, nucleoli and microvilli were prominent structures of cryofractured oocytes. Numerous cytoplasmic projections of granulosa cells and oocyte microvilli penetrated the zonae pellucida of preantral follicles. The numbers of oocyte microvilli were greatly diminished in large antral follicles. Other structures made prominent by cryofracture included cell nuclei, a microvillous border at the granulosa-theca boundary, and numerous holes in the cytoplasm of thecal cells which correspond in size and distribution to the liquid droplets in these cells. The soluble proteins and glycoproteins of the follicular fluid were visualized as a homogeneous granular precipitate. The disappearance of oocyte microvilli and granulosa cell projections from the zonae pellucida and the blebbing of granulosa cells at the surface of the antral cavity appeared characteristic of an early stage of follicular atresia. Increased numbers of holes in thecal cells, oocyte fragmentation, and extensive dissociation and fragmentation of granulosa cells were typical of more advanced stages of atresia.

In certain metallurgical applications of SEM, such as the observation of deformation effects, and the recovery and recrystallization processes in bulk specimens, it is of special interest to obtain information about local inhomogeneities of the dislocation densities in a sample. This can be obtained using TEM on thin foils. Previously information on distortion in cold-worked specimens was obtained by measuring the dependence of the deterioration of the resolution of the selected area channelling patterns (SACP) on the degree of deformation. This method, however, is not applicable to highly deformed materials. Direct SEM imaging of the cell structure of the dislocation network has been achieved without resolving single dislocations by using a suitable arrangement of specimen and detector, such that only backscattered electrons (BSE) leaving the surface at a large angle to the normal contribute to the image signals. The signal-to-noise ratio was improved to the degree that it was possible 1) to image the cell structure of the dislocation network and 2) on heating the specimens, to record the growth of recrystallized regions with TV-frame frequency. The imaging of the cell structure gives qualitative information about the degree of crystal deformation and the crystallographic direction of grain boundary motion during recrystallization.

(1988). Organizational Commitment: A Special Kind of Incentive. Hospital Topics: Vol. 66, No. 3, pp. 10-13.

Formalin-fixed fibres of sound and diseased meniscus have been analyzed by small-angle diffraction to get informations about structural changes in macromolecular dimensions. With degeneration of the meniscus fibres the small-angle pattern changed in a characteristics way. In the first stage of disease there were only changes in intensity of the diffraction lines but with increasing degeneration of the fibres the discrete reflexions of the 640-A period vanished more and more in a characteristic way and there appeared a continuous small-angle scattering, which increased in proportion to the degree of disease. The continuous small-angle diffraction being elliptical at first was getting more and more circular with the degeneration of the fibres. An analysis of the continuous small-angle diffraction after the method of Hosemann and Motzkus showed that the bands of fibres degenerated to rod-like substructures with an average diameter of about 200 A and a length of 600–800 A. In the first stages of degeneration they were orientated as the sound fibres (which showed the elliptic form of the continuous scattering), but this orientation got more and more lost with increasing disease (which was to be seen by the circular continuous scattering). The rod-like substructures are likely to degenerate further in more globular structures.

Visualization of chromosomal surface architecture using a new light-microscopical method A new method is described, by which the surface architecture of chromosomes can be visualized using light microscope. The principles of the method include 1. 1. the coating of chromosomes with a thin layer of evaporated gold to increase light reflection; 2. 2. the use of oblique and asymmetrical illumination which creates shadows across the surface of chromosomes such that elevations appear bright and depression dark. The chromosomes thus give a three-dimensional appearance. This method can be used to demonstrate correlations between the Giemsa banding pattern and the surface architecture of chromosomes: each Giemsa positive area clearly corresponds to an elevation of the chromosomal surface.

Es gelang, bei Anwesenheit von Silber und HCl lichtmikroskopisch vermeßbare Kupferoxydnadeln zwischen 200° und 300°C zu züchten. Sie bilden CuO-Einkristalle nach [110]. Als Nadelbegrenzungen traten häufig sechsseitige Prismen auf. Das Längenwachstum erfolgt linear (L=v[110] ·t) bis zur Inhibition. Die Temperaturabhängigkeit der Längenwachstumsgeschwindigkeit wird angenähert durch die empirisch ermittelte Funktion v[110] = A e-B/T bestimmt. Bei konstanter Temperatur zeigen einzelne Nadeln unterschiedliche Längenwachstumsgeschwindigkeit. Kristallwachstum und Keimbildung werden als geschwindigkeitsbestimmende Vorgänge angenommen. Es werden Möglichkeiten für eine genügend schnelle Oberflächenwanderung der „Bausteine“ zur Wachstumsstelle an der Nadelspitze diskutiert. Versetzungen können die Nadelbildung wesentlich beeinflussen und geben eine Erklärung für die beobachteten Temperaturgrenzen des Nadelwachstums.

The critical point method of drying biological specimens for electron microscopy has been applied to an unusual microorganism from soil. Specimens were prepared for scanning and transmission electron microscopy and some preliminary results are described.

Crystal growth on high-temperature corrosion layers of Cu 2 O, CuO and NiO was investigated by electron microscopy. From kinetic reasons we derive the existence of a reaction diffusion layer (RD-layer) on surfaces of the growing corrosion layers acting as mother phase for the crystallization process. The RD-layer probably consists of oxide molecules. Another feature of crystal growth on high-temperature corrosion layers is the existence of faces which have grown repetitively and isotropically, in addition to smooth growth faces and such with subindividuals bounded by small and smooth surface elements. Also, the possibility of a transition from a lateral growth mechanism to one of continuous growth with increasing supersaturation in the RD-layer was observed. Needle growth can now be explained in analogy to “bulge growth”.

Erkranktes menschliches Sehnengewebe zeigt im Rontgendiagramm eine Zerstorung der helicoidalen Struktur der Peptidketten und Auflosungen der Makrostruktur innerhalb der Ultrafibrillen an. Die 640 A-Langperiode geht vollig verloren. Statt dessen zerfallt die Faser in etwa 600 A lange Segmente, die teilweise aus 2–3 Unterbereichen bestehen. Man kann sie auch im Elektronenmikroskop an Einkerbungen in den Ultrafibrillen erkennen. Die Infrarotabsorptionsbanden der peptidischen Bindung werden dementsprechend etwas geschwacht, wobei als Folge aufgebrochener Ketten zwei neue Bande auftreten.

Fur die Korrosion spielt neben der globalen Materialbeschaffenheit auc die Mikromorphologie einschlieslich der Risse und Poren eine grose Rolle. Hierbei handelt es sich um feine Reliefstrukturen. Zu deren Untersuchung eignet sich vor allem das Raster-Elektronenmikroskop, und zwar wegen seiner hohen Tiefenscharfe und der verhaltnismasig einfachen Erstellung der Praparate. Die Anwendungsmoglichkeiten werden am Beispiel der Risbildung im Stahl bei mechanischer Beanspruchung, der Risbildung in der Schutzschicht in Dampfkesselrohren bei lokaler Uberhitzung, der Lochfraskorrosion und der Hochtemperaturoxydation von Cu und Ni erlautert. Determination of the state of the surface during corrosion processes Corrosion depends from the overall properties of the material and, in addition, from the micromorphology including pores and cracks. These factors constitute very fine relief structures which can be investigated most suitable by teh scanning electron microscope, in particular because of the high depth of focus and the relatively simple preparation of the specimens. Potential applications are illustrated on the example of crack formation in the protective layer in boiler tubes after local overheating, of pitting corrosion and of the high temperature oxidation of Cu and Ni.

Die Raster-Elektronenmikroskopie ermoglicht die unmittelbare Oberflachenuntersuchung von Lackschichten bzw. von dem Untergrundmaterial. Sie liefert bei einfachster Praparatvorbereitung plastisch wirkende Bilder von 20- bis 50000facher Vergroserung mit ausergewohnlicher Tiefenscharfe bei einem Auflosungsvermogen von 30 nm. Sie schliest gewisse Lucken der Untersuchungstechnik bei der Lichtmikroskopie bezuglich der Tiefenscharfe und bei der konventionellen Durchstrahlungs-Elektronenmikroskopie bezuglich der Praparation. Auf die mogliche Gewinnung einiger Daten fur Pigmente in Lackschichten mittels Raster-elektronenmikroskopischer Untersuchungen wird hingewiesen. New Possibilities of Surface Investigation in Paint Research with electron-Microscopic Scanning A direct surface investigation of paint layers and material of the background is possible with the help of electron-microscopic scanning. With a simple procedure of sample preparation, it produces 20 to 50000 times enlarged pictures with plastic appearance having exceptionally good depth sharpness at a resolving power of 30 nm. The said procedure eliminates a few drawbacks of light microscopy, namely those related to depth sharpness and to sample preparation, as encountered in conventional transmission electron microscopy. Possibilities of extracting a few data for pigments in paint layers with the help of electron-microscopic scanning investigation are indicated.

Fluorescein-labeled antigen-antibody complexes could be made visible by scanning electron microscopy using an intensifying device. This new method of immunocathodoluminescence was demonstrated on cryostat sections of rat kidneys containing glomerular fibrin as the result of endotoxin infusion. The resulting photographs correspond with those obtained by immunofluorescent microscopy. The advantage of this technique is, however, the larger depth of focus. By using thinner cyostat sections it is expected that the higher resolution of scanning microscopy will provide even better details in three dimensions.

The mechanisms of transport of molecules across the extravascular spaces represent an open problem. Vital microscopic results with marked proteins using the blue light luminescence technique indicate a movement of fluid along the connective tissue fibres. Furthermore, the findings suggest that the elastic fibres play an important role in this movement. It may also be possible to elucidate the extravascular pathway for molecules by means of the cathodoluminescence technique in the scanning electron microscope. The investigations were performed using the mesentery of mammalians anaesthetized by Nembutal. The biological material for cathodoluminescence applications was selected from animals without injection of luminescent dye as well as with animals following intravenous injection of marked proteins. Two techniques, critical point drying and freeze drying, were used in the preparation. Stained and unstained tissues were investigated in the scanning electron microscope with a special cathodoluminescence detector system. Simultaneously observations of the tissue surfaces were performed by means of the secondary electron or backscattered electron mode. The results obtained agree with the findings observed by the blue light fluorescence microscopy and confirm the concept of an extravascular fluid pathway along the elastic fibres in the tissue.

One feature of the Laser Microprobe-Mass-Analyzer (LAMMA) is the analysis of biomedical specimens. This method allows to obtain qualitative and quantitative information about the inorganic and--in a qualified sense--about the organic constituents of microvolumes of thin histological sections or of single cells (e.g. erythrocytes) with a relative sensitivity going down to the sub-ppm range. The paper describes the technical structure and features of the laser-microprobe, its advantages and possibilities, but also its limits in the investigation of biomedical specimens. This will be pointed out by some examples: 1) Analysis of blood from patients suffering from renal insufficiencies (A1 transportation, Fe/Mg ratio of erythrocytes). 2) Pb detection in fetal tissues after maternal Pb intoxication. 3) Analysis of trace elements (detection limits and superposition of organic background from embedding material). 4) Analysis of isotopes and molecules. The present contribution is not so much a discussion of medical problems, but mainly a discussion about the methodical and practical use of the laser microprobe.

Toxoplasma gondii, strain RH, produced plaques in human fibroblast tissue cultures over the temperatures 30–41 C. Muta⋗enesis with N-methyl-N′-nitro-N-nitrosoguanidine yielded seven temperature-sensitive mutants that had lost the ability to form plaques at 40 C but still grew well at 33 C. No spontaneous mutants were detected. The temperature-sensitive mutants were not markedly thermolabile and adsorbed normally to tissue culture cells at 40 C. Three mutants differed from one another in their temperatures for optimal growth, and in their ability to remain infectious within cells incubated at 40 C. Both mutants that were tested were found to be markedly less virulent for mice than was the wild type RH strain.

Die Analyse von Staubteilchen ist ein Hauptproblem der Silikose-Grundlagenforschung. Hier hat sich das Schwergewicht nach immer kleineren Korngrosen verlagert, da jetzt Teilchen unter 0,2 μ als besonders gefahrlich angesehen werden. Fur eine Gestalt- und Substanzanalyse dieser feinsten Staubteilchen versagen die bisher ublichen optischen Methoden. Fur erstere verwendet man deshalb die Elektronenmikroskopie.

Zur licht- und elektronenmikroskopischen Auswertung von Staubniederschlagen gibt es viele Verfahren. Hier soll eine kleine Verbesserung der bisher ublichen Verfahren gebracht werden, die es gestattet, dieselbe Staubprobe erst eingebettet lichtmikroskopisch und anschliesend elektronenmikroskopisch zu untersuchen und die vielleicht fur wissenschaftliche und routinemasige Untersuchungen weiter ausgebaut werden kann.