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- Haftfestigkeit (4)
- Klebfestigkeit (3)
- Acoustic levitation (2)
- Mass spectrometry (2)
- Mehr-Proben-Vorbehandeln/Kleben/Prüfen (2)
- 16S amplicons (1)
- ALD-Abscheidungen (1)
- Adhesion (1)
- Adhesives and adhesive tapes (1)
- Aeolian (1)
Organisationseinheit der BAM
Paper des Monats
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Aufzählung der wichtigsten wissenschaftlich-technischen und anderer wesentlicher Ergebnisse
• ALD Abscheidungen auf Polymeren (PE, PP, PTFE) unter Atmosphärendruck und im Vakuum mit Ozon als Oxidationsmittel wurden durchgeführt:
- Mit Variation der Schichtdicke
- Mit Variation der Zykluszeit
- Mit und ohne Ozon Vorbehandlung der Oberfläche
• ALD Abscheidungen auf (PE, PP, PTFE) in Vakuum mit O2- und H2-Plasma Vorbehandlung wurden durchgeführt.
- Mit Variation der Schichtdicke
- Mit Variation der Zykluszeit
- Mit und ohne Plasma Vorbehandlung der Oberfläche
• Die ALD Prozesse wurden mit in situ Laserellipsometrie untersucht.
• Die ALD Schichten wurden für die Haftfestigkeit bei der BAM ausgewerte
The multiple-sample approach by means of centrifugal adhesion testing (CAT-technology) allows the determination of bonding strength of adhesive-bonded joints on a statistical basis of up to eight samples. Therefore, it is obvious to ensure the continuous handling and identical processing of an octet of samples within the entire process chain of wet-chemical cleaning, plasma-chemical pre-treatment, bonding of samples, and testing of bonding strength. Within the multiple-sample bonding set-up (MPKV-technology) a defined bonding pressure can be adjusted regardless the actual number of samples. A comparison of single- and multiple-sample approach is made for bonding strength of selected adhesives, double-sided adhesive tapes and different material combinations [stainless steel (V2A) vs. stainless steel, polyamide (PA), or polypropylene (PP)]. It is shown that both technologies improve reliability of results
Die Bestimmung der Haftfestigkeit von Lackierungen, Beschichtungen oder Klebeverbunden ist ein wichtiges Analyseinstrument bei der Beurteilung von entsprechenden Fertigungsabläufen. Unter Verwendung einer neuen Zentrifugentechnologie wurde in einem AiF Forschungsprojekt OKTETT die gesamte Prozesskette Vorbehandlung - Verklebung - Prüfung validiert.
Decorative hard coatings: interdependence of optical, stoichiometric and structural properties
(1993)
Ancient mariners knew that dust whipped up from deserts by strong winds travelled long distances, including over oceans. Satellite remote sensing revealed major dust sources across the Sahara. Indeed, the Bodélé Depression in the Republic of Chad has been called the dustiest place on earth. We analysed desert sand from various locations in Chad and dust that had blown to the Cape Verde Islands. High throughput sequencing techniques combined with classical microbiological methods showed that the samples contained a large variety of microbes well adapted to the harsh desert conditions. The most abundant bacterial groupings in four different phyla included: (a) Firmicutes—Bacillaceae, (b) Actinobacteria—Geodermatophilaceae, Nocardiodaceae and Solirubrobacteraceae, (c) Proteobacteria—Oxalobacteraceae, Rhizobiales and Sphingomonadaceae, and (d) Bacteroidetes—Cytophagaceae. Ascomycota was the overwhelmingly dominant fungal group followed by Basidiomycota and traces of Chytridiomycota, Microsporidia and Glomeromycota. Two freshwater algae (Trebouxiophyceae) were isolated. Most predominant taxa are widely distributed land inhabitants that are common in soil and on the surfaces of plants. Examples include Bradyrhizobium spp. that nodulate and fix nitrogen in Acacia species, the predominant trees of the Sahara as well as Herbaspirillum (Oxalobacteraceae), a group of chemoorganotrophic free-living soil inhabitants that fix nitrogen in association with Gramineae roots. Few pathogenic strains were found, suggesting that African dust is not a large threat to public health.
Single Femtosecond Laser-Pulse-Induced Superficial Amorphization and Re-Crystallization of Silicon
(2021)
Superficial amorphization and re-crystallization of silicon in <111> and <100> orientation after irradiation by femtosecond laser pulses (790 nm, 30 fs) are studied using optical imaging and transmission electron microscopy. Spectroscopic imaging ellipsometry (SIE) allows fast data acquisition at multiple wavelengths and provides experimental data for calculating nanometric amorphous layer thickness profiles with micrometric lateral resolution based on a thin-film layer model. For a radially Gaussian laser beam and at moderate peak fluences above the melting and below the ablation thresholds, laterally parabolic amorphous layer profiles with maximum thicknesses of several tens of nanometers were quantitatively attained. The accuracy of the calculations is verified experimentally by high-resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (STEM-EDX). Along with topographic information obtained by atomic force microscopy (AFM), a comprehensive picture of the superficial re-solidification of silicon after local melting by femtosecond laser pulses is drawn.
Microbiological studies on the intercontinental transport of dust are confounded by the difficulty of obtaining sufficient material for analysis. Axenic samples of dust collected at high altitudes or historic specimens in museums are often so small and precious that the material can only be sacrificed when positive results are assured. With this in mind, we evaluated current methods and developed new ones in an attempt to catalogue all microbes present in small dust or sand samples. The methods used included classical microbiological approaches in which sand extracts were plated out on a variety of different media, polymerase chain reaction (PCR)-based amplification of 16S/18S rRNA sequences followed by construction of clone libraries, PCR amplification of 16S rRNA sequences followed by high-throughput sequencing (HtS) of the products and direct HtS of DNA extracted from the sand. A representative sand sample collected at Bahaï Wadi in the desert of the Republic of Chad was used. HtS with or without amplification showed the most promise and can be performed on ≤100 ng DNA. Since living microbes are often required, current best practices would involve geochemical and microscopic characterisation of the sample, followed by DNA isolation and direct HtS. Once the microbial content of the sample has been deciphered, growth conditions (including media) can be tailored to isolate the micro-organisms of interest.