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Metal containing and metal free amorphous diamond-like carbon films were prepared by reactive magnetron sputter deposition using targets from transition metals or graphite and acetylene as reactive gas. Both types of coating materials are well known for their low friction coefficients. However, metal containing films exhibit clearly lower wear resistances and lower hardness values than metal free films. To study the differences between both materials, tungsten containing and metal free coatings were compared. The deposition experiments were carried out in an industrial scale d.c. magnetron sputter machine. Transmission electron microscopy, secondary ion mass spectroscopy, and Raman spectroscopy as well as hardness measurements and wear tests were performed to characterize and to compare composition, structure, mechanical, and tribological properties of both coating materials.

The Dodge's long overhangs and the heavy big-block V8 sitting over the front axle remind you that America's road network is rather less demanding than your average European B-road - this car's main objective was to go straight ahead, for at least a quarter of a mile - but rarely is a classic with such a completely overwhelmed chassis so much fun, with every fast corner becoming an entertaining adventure. Our test car rolled off the assembly line in 1970 as a basic 307cu in Chevy Malibu, but today it's a Chevelle SS clone with a hot-rodded 383cu in V8 pushing out around 400bhp. Every manufacturer soon had its own muscle-car model in the range as Big Three Chrysler, Ford and General Motors outbid each other with colourful psychedelic advertising campaigns, aggressive slogans and wacky performance figures for their overpowered vehicles. On America's high-speed ovals, Chrysler's bewinged coupes could top 180mph, when more than enough air was blown through the limited nasal opening to cool the powerful 7.2-litre V8. [Extracted from the article]

Um das Ziel zu erreichen, Stahlzahnräder hinsichtlich Tragfähigkeit und Verschleiß zu optimieren, wurden in diesem Vorhaben Beschichtungen erprobt. Im Rahmen von Vorarbeiten wurden verschiedene Schichtsysteme numerisch mit der Software ELASTICA® auf ihre Eignung geprüft. Dabei wurden die Eigenschaften der Schichtsysteme abhängig vom Werkstoff, seiner Oberflächenbehandlung sowie den Radien relevanter Wälzpartner bestimmt. Unterschieden wurden makroskopische Wälzkontakte zwischen den Zahnflanken sowie mikroskopische Kontakte mit Oberflächenrauheit sowie Abriebpartikeln. Die vier am besten geeigneten Schichtsysteme wurden zunächst auf vereinfachte Rollkörper aufgetragen und unter verschiedenen Bedingungen geprüft. Dadurch wurden zwei Schichtsysteme ermittelt, die besondere Eignung für die Beschichtung der Zahnräder zeigen: a:C‐H mit CrN‐Stützschicht sowie a:C‐H mit CrN‐Stützschicht und vorhergehender Plasmanitrierung (Duplex‐Prozess). Um die Schichten auf den Zahnflanken gegen Eingriffsstöße zu schützen, wurde deren evolventisches Profil mit einer Kopfrücknahme versehen. Als Zahnradwerkstoffe wurden 16MnCr5, 42CrMo4 sowie der Sonderstahl ETG®88 eingesetzt. Als Schmiermittel kamen zwei Arten von Fließfetten zum Einsatz. Zudem wurde der Trockenlauf untersucht. Die Zahnräder wurden bei drei verschiedenen Drehzahlen geprüft. Geprüft wurden die Zahnräder auf einem eigens dafür konstruierten Prüfstand. Die Prüfung verlief in sogenannten Kraftstufen. Jede Stufe steht für eine feste Anzahl von Wälzkontakten, d. h. Umdrehungen der Zahnräder, sowie für ein bestimmtes Drehmoment, das eine Hertz'sche Pressung auf den Zahnflanken hervorruft. Mit steigender Stufenzahl wird das Drehmoment erhöht. Das Schadenskriterium ist der Beginn des Fressens des Grundwerkstoffs als Indikator, dass das jeweilige Schichtsystem seine Schutzwirkung eingebüßt hat. Die Versuchsergebnisse zeigten, dass insbesondere bei den Stählen 16MnCr5 und 42CrMo4 das Schichtsystem a:C‐H mit CrN‐Stützschicht und vorhergehender Plasmanitrierung zu nennenswerten Steigerungen der Flankentragfähigkeit und des Verschleißschutzes führt. Diese Steigerung wurde sowohl bei fettgeschmierten als auch bei trockenlaufenden Zahnrädern beobachtet. Die Ergebnisse für den Sonderstahl ETG®88 fielen weniger gut aus.

The diversity of the protist communities of the water column and ice along the Finnish coast of the Baltic Sea was studied during March 1994. The preliminary identification of the organisms was made light microscopically on live material, while further identification of e.g. scale-bearing flagellates was based on whole mounts using light and electron microscopy. The ice biota and the winter plankton was dominated by diatoms. Other abundant groups were choanoflagellates, chrysophytes, chlorophytes, dinoflagellates and protists of uncertain affinity. The highest brine salinities (up to 30%o) and the most diverse ice biota were found at two stations in the Bothnian Bay, where the number of recorded taxa was 71 and 74. In the water column the numbers were much lower (34 and 42). In the Bothnian Sea and along the southern coast of Finland the ice biota was less diverse, and the number of protist taxa ranged from 21 to 47. A few taxa showed a special preference for the ice habitat. New distribution records to the Baltic Sea are Navicula pelagica(Bacillariophyceae), Cryothecomonas armigera(Protista incertae sedis), and the genus Polytomella(Chlorophyceae). The abundance and vertical distribution of C. armigera, other flagellates, Monoraphidium contortion(Chlorophyceae), and diatoms in the ice at station I was studied using inverted light microscopy and sedimentation chambers. M. contortumwas found to be the cause of a distinct green colouration of the ice. With the exception of C. armigera, all other protist taxa formed well-defined maxima within the ice interior. The number of cells in such abundance peaks varied from approximately 2.5×105M. contortumcells 1−1to 2×106diatoms 1−1of melted sea ice.

Summary The prasinophycean flagellatePyramimonas orientalis has been examined by light and electron microscopy of wild and cultured material. The many different scales which cover all cell surfaces, including the flagella, are described; their synthesis and assembly in the two Golgi bodies have been examined. The Golgi bodies work simultaneously to produce all-at least five—scale categories, including hollow hair shaped scales. From the Golgi system the scales become transported to a special container—a reservoir—in which they, in an unknown way, separate and become arranged in the same pattern as on the body surface. From the reservoir, the scales move through a duct to the cell surface, apparently together with the subtending membrane, which thus becomes incorporated in the plasmalemma or the flagellar membrane. The liberation process, which differs from that of other species ofPyramimonas examined, is illustrated diagrammatically, starting at two extensions of ER from the nuclear envelope.

The loricate choanoflagellate Bicosta spinifera was observed frequently in Antarctic samples collected along Scotia/Weddell Sea transects. The entire population showed a conspicuous bimodal size distribution. Large forms were predominant in Scotia Sea samples, while only small specimens were found in the Confluence area. Prior to cell division Bicosta spinifera produces a complete set of costal strips in a temporary “tail”-like protrusion. Small specimens sometimes possess a “tail” similar to that found in large specimens. The fact that B. spinifera may increase considerably in size following cell division, in connection with the finding of aberrant minute forms, have prompted us to hypothesize a polymorphic life history in B. spinifera. The term “caudiform” division is introduced to describe division in B. spinifera. Saroeca attenuata also produces a “tail” prior to cell division, but is otherwise shown to undergo a mixed caudiform/tectiform type of division.

During the winter of 1985 the uppermost part of the water column of the ice-covered Danish fjord, Isefjorden, was coloured yellowish brown by a growth of the small flagellate Pseudopedinella tricostata (ca. 75 × 106 cells 1-1). The species differs from others of the genus by having three chloroplasts only, each with an embedded pyrenoid. In March a distinct yellowish band was found in the lower part of the ice which electron microscopical examination showed to be due to the presence of millions of cysts of P. tricostata. The P. tricostata cyst has a continuous three-layered wall, thus differing markedly from the typical bipartite chrysophycean cyst. The outermost wall-layer contains a significant amount of iron.

Abstract: During the spring of 1996 we occupied a station on annual sea ice located several kilometers from Disko Island, West Greenland in water depths greater than 200 m. The goal of this 3-week field season was to characterize sea-ice communities and the underlying water column prior to, and during, ice break-up. A heavier than usual snow load depressed the sea ice below sea level and the snow-ice interface became flooded. Some of this flooded region subsequently refroze and the whole process repeated itself when additional snow accumulated. The infiltration phytoplankton and protozooplankton assemblages that developed in this region were abundant and diverse. Algal biomass in the infiltration layer was approximately an order of magnitude greater than in the underlying water column but an order of magnitude less than in the well-developed bottom ice community. The infiltration autotrophic assemblage resembled the bottom-ice assemblage while the protozooplankton assemblage was more similar to the water column assemblage.

AbstractNo abstract available.

A new loricate choanoflagellate genus, Spinoeca buckiigen. et sp. nov., is described from West Greenland. The lorica has four conspicuous spines at each end. The transverse costal component includes a single anterior transverse costa, and pairs of crossing (X-shaped) costal strips at the posterior lorica end. The lorica appears to be open also at the posterior end. In addition to West Greenland, the new taxon is reported from several places in the North Atlantic (including the high Arctic), Arctic Canada, and South America. The West Greenland loricate choanoflagellate community (August 1988) comprised more than 32 species. Ten of these accounted for more than 90% of the total population.

Recent opportunities to sample live material from in particular the Antarctic ice biota have resulted in the discovery of numerous autotrophic and heterotrophic flagellate components of this community. In certain samples, some of these hitherto neglected types of organisms are obviously key components of the ice biota. One such example is found in species of the heterotrophic flagellate genus Thaumatomastix(Thaumatomastigidae, Protista incertae sedis). Three new species are described (T. splendidasp. nov., T. fragilissp. nov., and T. fusiformissp. nov.) one of which (T. splendida) has been found to be ubiquitous in Antarctic sea ice and also most likely a significant member of the Arctic sea ice community.

Electron microscopical examination of whole mounts, prepared from freshly collected seawater samples from the Isefjord area (Denmark), has led to the enumeration of seven species belonging to the chrysophycean genus Paraphysomonas. One of these is P. sideriophora sp. nov., characterised by its single type of scale, each resembling a flat-iron. Three of the species have previously been recorded from Denmark.Most of the type descriptions of Paraphysomonas species refer to accidentally cultured material. When the same species are observed under natural conditions, as in the present investigation, the variation in scale size and morphology is seen to be considerably wider than reported in the type descriptions. This applies in particular to P. foraminifera Lucas and P. imperforata Lucas. The discrepancies between the type descriptions and the present material is probably a reflection of the fact that cultured material consists of one or a few clones only (sexual reproduction is unknown), whereas the immediate processing for electron microscopy of freshly collected seawater samples, carried out over a longer period, probably provides material from several clones.The taxonomy of the various scale-covered heterokont genera of the Ochromonadales is briefly discussed.

Eleven taxa of nanoplanktonic coccolithophorids are reported from West Greenland on the basis of material collected in the vicinity of Godhavn (Disko Island) in July and August 1977. Pappomonas flabellifera var. flabellifera is a new record for the northern hemisphere. Five of the species are new recordings for the Disko Bay area (Papposphaera sagittifera, Balaniger balticus, Calciarcus alaskensis, Wigwamma annulifera, and Turrisphaera arctica). A new species, Papposphaera sarion sp.nov., is described on the basis of transmission electron microscopy. It is distinguished from the two other Papposphaera species by a different type of appendage head. A summary of all the coccolithophorid data from 1977 show considerable variation within the area investigated with regard to the number of species present in each sample, as well as regarding the local distribution of certain species. The biogeography of the species recorded from West Greenland is considered. The inclusion of several records from nanoplankton investigations of Danish waters show that very few (if any) of these species are distributionally restricted to arctic or subarctic regions.

Wigwamma scenozonion sp. nov. (Prymnesiophyceae) is described on the basis of electron microscopy of shadowcast whole mounts prepared from water samples collected in the vicinity of Godhavn (West Greenland) in July and August 1977. This nanoplanktonic coccolithophorid possesses two smooth flagella and a shorter coiling haptonema. Coccoliths of one type cover the whole cell. Each coccolith is composed of a ring of rod-like crystallites joined end to end and arranged parallel to the edge of the oval coccolith base-plates. A single enlarged crystallite is found on most coccoliths. W. scenozonion is distinguished from the two previously described Wigwamma species by the lack of coccolith superstructures and by having one, rather than two rings of crystallites along the base-plate edge. In addition to the West Greenland specimens a single W. scenozonion cell has been encountered in a water sample from Denmark.

During late August 1985, a significant coccolithophorid contribution to phytoplankton biomass and diversity was evident in the inner Danish waters of the southern Kattegat and the Isefjord. The material included new taxa, one of which, Ericiolus spiculiger gen. et sp. nov., is now formally described together with a second, Antarctic species from the same genus, E. frigidus sp. nov. The genus comprises small, apparently heterotrophic species with a single type of calcified structure reminiscent of caltrops.