Comparison of the properties of biogenic wine by-products stabilized biocomposites compounded with a miniaturized single-screw extruder and a co-rotating twin-screw extruder

Bioplastics research is hindered by high material prices and limited availability of biopolymers. For conventional compounding, even on lab-scale, large quantities of material are required. In this study, an alternative process for compounding biocomposites was evaluated to investigate the potential of wine-derived biogenic by-products as functional fillers. Formulations based on poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and wine grape pomace (WP) with filler contents up to 10 wt.-% were prepared. The materials were processed with a modified miniaturized single-screw extruder (MSE) and compared to a lab-scale twin-screw extruder (TSE). Thermal and rheological properties of the materials were determined using GPC, MFR, DSC, TGA and OIT. The mixing quality of both extruders was evaluated by optical microscopy imaging. The results revealed that the MSE represents an efficient alternative for research purposes, but differences in the dominant degradation mechanisms during processing must be considered. Thermal analysis showed that WP successfully suppressed the thermo-oxidative degradation of PHBV

Kompression von DNA Sequenzen

Standardkompressionsverfahren erreichen bei Texten, die Programmkode oder menschliche Sprache enthalten, sehr hohe Kompressionsraten. DNA Sequenzen weisen eine lineare Basenabfolge auf und können daher auch als Texte betrachtet werden. Allerdings gelingt es den Standardkompressoren in den meisten Fällen nicht, DNA Sequenzen zu komprimieren. Selbst wenn sich eine DNA Sequenz komprimieren läßt, ist die Kompressionsrate äußerst gering. Es gibt zwei mögliche Erklärungen für diese Beobachtung. Entweder sind DNA Sequenzen generell nicht komprimierbar oder die bisherigen Kompressoren sind dazu nicht in der Lage. In dieser Diplomarbeit soll diese Frage untersucht werden. Dabei wird sich herausstellen, daß sich auch DNA Sequenzen komprimieren lassen, wenn ein Kompressor charakteristische Eigenschaften ausnutzt. Es werden wesentliche Unterschiede von menschlicher Sprache zu DNA Sequenzen erläutert und DNA spezifische Kompressionsverfahren vorgestellt. Kompression läßt sich nicht nur zur Reduktion des benötigten Speichers verwenden, sondern es gibt eine Vielzahl an Anwendungsgebieten, wo Kompressionsverfahren in der Biologie eingesetzt werden können. So lassen sich phylogenetische Bäume mit Hilfe von Kompressionsverfahren aus genetischen Daten rekonstruieren. Auch zur Charakterisierung von unterschiedlichen Regionen im Genom kann ein Kompressor verwendet werden. Im zweiten Teil der Arbeit wird auf diese Gebiete näher eingegangen. Dabei werden praktische Versuche durchgeführt, um Nutzen und Anwendbarkeit genauer zu untersuchen, aber auch um Grenzen der Methoden aufzuzeigen

Non-EST based prediction of exon skipping and intron retention events using Pfam information

Most of the known alternative splice events have been detected by the comparison of expressed sequence tags (ESTs) and cDNAs. However, not all splice events are represented in EST databases since ESTs have several biases. Therefore, non-EST based approaches are needed to extend our view of a transcriptome. Here, we describe a novel method for the ab initio prediction of alternative splice events that is solely based on the annotation of Pfam domains. Furthermore, we applied this approach in a genome-wide manner to all human RefSeq transcripts and predicted a total of 321 exon skipping and intron retention events. We show that this method is very reliable as 78% (250 of 321) of our predictions are confirmed by ESTs or cDNAs. Subsequent analyses of splice events within Pfam domains revealed a significant preference of alternative exon junctions to be located at the protein surface and to avoid secondary structure elements. Thus, splice events within Pfams are probable to alter the structure and function of a domain which makes them highly interesting for detailed biological investigation. As Pfam domains are annotated in many other species, our strategy to predict exon skipping and intron retention events might be important for species with a lower number of ESTs

Pre-mRNA Secondary Structures Influence Exon Recognition

The secondary structure of a pre-mRNA influences a number of processing steps including alternative splicing. Since most splicing regulatory proteins bind to single-stranded RNA, the sequestration of RNA into double strands could prevent their binding. Here, we analyzed the secondary structure context of experimentally determined splicing enhancer and silencer motifs in their natural pre-mRNA context. We found that these splicing motifs are significantly more single-stranded than controls. These findings were validated by transfection experiments, where the effect of enhancer or silencer motifs on exon skipping was much more pronounced in single-stranded conformation. We also found that the structural context of predicted splicing motifs is under selection, suggesting a general importance of secondary structures on splicing and adding another level of evolutionary constraints on pre-mRNAs. Our results explain the action of mutations that affect splicing and indicate that the structural context of splicing motifs is part of the mRNA splicing code

A Modular Multilevel Matrix Converter for High Speed Drive Applications

The Modular Multilevel Matrix Converter (M3C) performs a direct three-phase AC to AC power conversion and is highly suitable for medium voltage high power drive applications. One area of application are high speed drives such as compressors. However, additional balancing power components which reduce the output power capability of the M3C when input and output frequencies are similar occur. This paper analytically examines the operation behavior and power capability in these operation points in order to assess whether the M3C can generate these additional components without oversizing the converter\u27s components. Subsequently, the theoretical evaluation is verified by a laboratory scaled prototype with a rated power of 15 kW