Den Energieniveaus auf der Spur

Tracking energy levels – Photoelectron spectroscopy helps in finding novel semiconductor materials Research on novel semiconducting materials keeps attracting considerable interest due to the potential to develop more cost effective processing compared to conventional inorganic technology. Maybe more importantly, novel device concept become possible such as flexible or semitransparent displays and solar cells. Two of the most promising candidates are introduced here: organic semiconductors as well as halide perovskites. In both material classes, it is possible to tune the absorption or emission properties over a wide range by adjusting the structure or composition or the material. In order to effectively integrate these materials in devices, it is necessary to understand their fundamental properties. Here, the vacuum based photoelectron spectroscopy plays an important role, due to the possibility to directly map the electronic structure of the semiconducting or adjacent layers, which in turn determines the charge transport throughout the device.     

Probleme der geometrischen Synthese von Schaufelradaufbauten,basierend auf der Struktur der Viergelenkkette

Zusammenfassung Besprochen werden die Vorteile eines Auslegers mit allgemeiner ebener Bewegung gegenüber dem Ausleger mit nur Drehbewegung. Beschrieben wird die Methode zur Bestimmung geometrie von Schaufelrad-Aufbauten auf der Basis der Struktur der Viergelenkkette mit allgemeiner ebener Bewegund des Auslegers. Es wird auch dei M?glichkeit der übertragung des F?rdergutes vom Schaufelrad zur vertikalen Maschinendrehachse erl?utert.     

Neuere Entwicklungen auf dem Gebiet der Vakuumbogenbeschichtung

Actually millions of tools and engine components are coated with hard coatings by cathodic vacuum arc deposition monthly. Most of the coatings are applied for abrasion protection. But also coatings for decoration or corrosionprotection are usual. The most important coating is TiN, but also a great number of different kinds of coatings are available for various applications. Recent developments are dedicated to fit the coat- substrat combination for the specific application or to coat materials with a low thermal load capacity. On the other hand the technology of the coating- devices are improved permanently. Coating chambers from a size of some ten centimetres to some metres with fully automatic process control are available.     

Resorbierbarer Knochenersatz auf der Basis von Calciumphosphaten

Resorbable bone substitution on the basis of calcium phosphates Besides hydroxyapatite (HAp), tricalcium phosphate is increasingly being used as bone substitution material. In literature there are contradictory claims of the TCP solubility. As a result of are contradictory claims of the TCP solubility. As a result of different manufacturing processes there are altered material properties, which are documented by different resorption behaviour especielly after implantation (particle separation, chemical solvatation). To clarify of such in vitro connections two methods for determining the solubility were investigated. Especially for this case, TCP samples prepared from different raw materials were synthesized. These samples were given different heat treatments and/or posttreatments with phosphoric acid. The materials were characterized above all by using X-ray powder diffraction method and scanning electron microscopy. Following investigations of the solubility lead to optimized testing parameters (solvent, concentration, ratio of solvent's quantity to sample surface, etc.) as well as qualified test parameters (lost of weight, ion concentration). When the test conditions were carefully selected, the in vitro solubillity was proved to be a very effective possibility of materials characterisation which is also very sensitive regarding chemical differences caused by synthesizing or morphological differences.     

Entwicklungstendenzen auf dem Gebiet der organischen Beschichtungen

Development trends in the field of organic coatings . Modern materials for organic coatings are supposed to permit economic processing and should be unobjectionable in environmental terms. These requirements can only incompletely be satisfied by modification of conventional products. Thus the aspects are good for water-soluble binders as well as for solvent-less materials curing by chemical reaction only. However, developments in the processing field are becoming even more important than those of materials. Electrostatic spraying procedures and dipping techniques with trichlorethylene as solvent demonstrate the progress made in generally approved methods. The use of powder as coating material, the method of film-curing by electron beams, and the electro-coating process, however, are novel procedures based on appropriate physical effects.     

Forschungsarbeiten auf dem Gebiete der technischen Thermodynamik

Zusammenfassung Zusammenfassender Bericht über 31 thermodynamische Probleme betreffende Abhandlungen der Sammlung „Forschungsarbeiten auf dem Gebiete des Ingenieurwesens”— Metalle—Wasserdampf—Ammoniak, Kohlens?ure, Stickoxyd—Luft und Sauerstoff —Organische Stoffe     

Theorie der schubweichen Kreisplatte auf elastischer Unterlage

Zusammenfassung Unter Berücksichtigung der Querschubverzerrungen wird eine verschärfte Theorie der drehsymmetrisch belasteten unendlichen Platten sowie der Kreis- und Kreisringplatten auf elastisch nachgiebiger Unterlage entwickelt. Die allgemeine Lösung des Problems wird in Zylinderfunktionen im komplexen Bereich angegeben.

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Summary A refined theory for infinite, circular and ring plates resting on an elastic foundation is developed taking deformations due to shear into account. Load distribution has rotational symmetry. The general solution is given in terms of complex cylinder functions.

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Mit 3 Textabbildungen     

Anwendung der Beugungstheorie auf Rechnerisch Korrigierte Mikroskopobjektive zur Beurteilung der Restfehler

Die rechnerische Korrektion optischer Systeme nach den üblichen geometrisch-optischen Strahlendurchrechnungen erfährt eine für Mikroskop-Objektive sinnvolle Ergänzung durch ein beugungstheoretisches Berechnungsverfahren für die Helligkeitsverteilung im Bilde eines punktförmigen Selbstleuchters unter Berücksichtigung monochromatischer Bildfehler beliebiger Mischung, aber beschränkter Größe. Diese Helligkeitsverteilung wird als Grundlage zur Beurteilung der Abbildungsqualität angesehen. Das vorgestellte Verfahren wird an Mikroskop-Objektiven der Firma Ernst Leitz GmbH. Wetzlar demonstriert. Der Rechnungsgang eignet sich zur Programmierung für einen Rechenautomaten; es wird empfohlen, die Helligkeitsverteilung direkt vom Fernschreiber als Typenraster ausdrucken zu lassen.     

Quantitative Bewertung von Werkstoffinhomogenitäten auf der Basis der Bruchmechanik

Today it is impossible to quantitatively judge defects of welded joints, because a definite connection between defect and failurestress does not exist. Based on fracture mechanics a theoretical connection is produced between the portion of defects in a welded joint and the failurestress of such a welded component (plate or pipe). It Proved right that the failure-stress is dependent upon both the ratio K_c/σ* (K_c = fracture toughness; σ* = flow stress) and the component-size, whereas the allowable portion of defects rise with increasing K_c/σ* However, the allowable portion of defects decrease with increasing component-size.     

Funktionelle Schichten auf der Basis von Hybridpolymeren

Functional layers on the base of hybrid polymers The present study describes the synthesis and application of functional nanoparticles based of silicon. Examples for technical interesting applications are antiadhesive layers, layers with adjustable hydrophobic/hydrophilic properties of the surface as well as porous layers for ink‐jet‐materials. By reaction of functional nanoparticles with maleic acid copolymers or polyepoxides hybrid polymers can be obtained which have good barrier properties depending from their structure and are useful as protective coatings for plastic container.