Refine
Year of publication
Document type
- Contribution to a Periodical (39) (remove)
Language
- English (39) (remove)
Is part of the Bibliography
- No (39) (remove)
Keywords
- Apache Kafka (2)
- Smart home (2)
- Stream processing (2)
- API (1)
- Ambient assisted living (1)
- Analysis (1)
- Apache Flink (1)
- Apache Tez (1)
- Artefacts (1)
- Artificial intelligence (1)
Course of studies
Parylene-C is used for various biomedical devices because of its high conformity and biocompatibility. However, delamination could occur because of low adhesion between Parylene-C and other materials. For this experiment 4-inch Si-wafers are used. Parylene is deposited by chemical vapour deposition (CVD). Silane A-174 as adhesion promoter is added between Parylene-Parylene layers. The samples are soaked at different duration 1 h, 24 h and 120 h in PBS solution at 37 °C. A peel test is further performed to investigate the adhesion properties of the samples.
This work gives the theoretical background which is needed to understand what self-assembling monolayers are, how they work, how and for what they can be used. A closer look is taken on the possibility to create an area selective atomic layer deposition process. In a practical experiment the foundation for this process is laid. Therefor a silicon wafer is coated with gold using a evaporation process. The gold samples are exposed to the SAMs solution to grow them. Contact angle measurements as well as Fourier transform Infrared spectroscopy are used to check the existence of SAMs on the gold samples. Also there is investigated if different exposure times make any differences.
Compared to relational databases, graph database systems provide a novel way of processing and analyzing highly interconnected data. Due to their unique properties, graph databases embody an interesting area of research in academic circles. For this reason, this work is fundamentally concerned with examining the state of the industry and current challenges. In this regard, we revisit the basic concepts and highlight the tremendous heterogeneity of available systems using the example of differing path semantics. Based on this insight, we explore algorithmic advancements for graph query processing regarding path finding and worst-case optimal joins. Subsequently, we discuss issues regarding performance and support for graph analytics. Finally, we provide an overview of GQL, a joint standardization effort towards unification of property graph databases.
Wikipedia is the largest free encyclopedia and one of the most popular websites worldwide. Analyzing user activity within this encyclopedic ecosystem represents unique opportunities for academic research and analysis. For this reason, this work is fundamentally concerned with obtaining and processing real-time article edit streams from Wikipedia. In this regard, we leverage the Wikimedia EventStreams API and propose a general-purpose event pipeline allowing for further processing of observed page edits. In the suggested pipeline, events are ingested and transported via an Apache Kafka cluster and inserted into a ClickHouse database for storage and analysis. Finally, we confirm the viability of our design by exploring several exemplary analytical use cases.
In the present work, polyetheretherketone (PEEK) was pretreated with oxygen plasma to investigate the influence on the contact angle and surface energy. For this purpose, PEEK samples were fabricated over several manufacturing steps, which were used as substrates for later investigations. A series of measurements was performed at a power of 300 W for different treatment durations and the contact angle of H2O on the PEEK surface was determined. The results show that plasma pretreatment significantly affects the surface modification of PEEK disks. The best hydrophilic properties of the PEEK surfaces were measured at a treatment time of 540 s and a power of 300 W. A much longer treatment time caused the correlated values of contact angle and surface energy to increase and in this case an excessive treatment time did not contribute to a further increase in hydrophilicity.
Investigation on adhesion strength of Parylene-C coatings with different adhesion promotion methods
(2021)
Delamination of encapsulation materials (here the polymer Parylene-C) is one of the biggest failure mechanisms for active medical implants. This problem is addressed by the application of different pre-treatment and adhesion promotion methods. The methods applied in this research are oxygen and Silane A-174 solution pre-treatment and Silane A-174, titanium oxide and Trimethylsilane as adhesion promoters. The adhesion forces of these methods are quantified after different soaking times in phosphate buffered saline (PBS) solution to mimic environment of the human body.
ALD can be used in medical technology to produce thin and stable protective coatings. For example, such coatings can be used as tarnish and oxidation protection for silver electrodes used in high-frequency surgery. For the investigation of the pretreatment method, platelets of sterling silver were used instead of silver electrodes. Three methods were used to pretreat the silver substrates. The first pretreatment method is cleaning with acetone and isopropanol. In the other two, the samples are additionally cleaned with a phosphoric acid etching mixture or citric acid. The pretreated substrates were coated using the atomic layer deposition method. 45 nm of aluminum oxide was deposited on the silver samples, followed by another 45 nm of titanium oxide. Subsequently, the samples were autoclaved in order to check the clinical routine and the reusability. The results show a significantly improved adhesion in contrast to samples that were not cleaned. The layer no longer flakes off the silver substrate. Nevertheless, small blisters appear on the protective layer after autoclaving. These indicate that the layer is weakened by the stress.