Numerical and Experimental Investigation of Thermoplastics in Multi-Axis Forming Processes

Process planning for multi-axis forming presses is a particular challenge. This process provides the option to actively influencing the material flow in the forming process by defining a six dimensional tool motion path and the tool velocity. By comprehending this interaction, it is possible to control and thereby tailor the induced local material properties of the workpiece. Experiments were conducted with a multi-axis press, which is based on a Stewart platform. A simple plane workpiece geometry is chosen to analyse the flow behaviour and the temperature evolution of the glass mat thermoplastics (GMT) during the forming process. Subsequently, a numerical simulation of the multi-axis forming process is carried out and validated with the experimental data. The numerical analysis focuses on the material modelling as well as the prediction of the flow characteristics. Regarding material modelling of GMT, an extensive material characterization is performed to describe the flow behaviour. A prediction of the flow behaviour of GMT with reference to tool motion is enabled. For the FE simulation the element-free Galerkin method (EFG) is applied for modelling the fluid structure interaction and adaptive procedures

Steigerung der Wertschöpfung ökologisch angebauter Marktfrüchte durch Optimierung des Managements der Bodenfruchtbarkeit

Das interdisziplinäre Bodenfruchtbarkeitsprojekt beschäftigte sich in vier Versuchs- und fünf Projektjahren mit den Zusammenhängen zwischen dem Anbau von Körnerleguminosen und Bodenfruchtbarkeit, insbesondere auf viehschwachen bzw. viehlosen Biobetrieben. In Erhebungen auf 32 Praxisbetrieben konnten bislang allenfalls vermutete Zusammenhänge wie z. B. die Zunahme des Unkrautdeckungsgrades mit zunehmendem Humusgehalt bestätigt werden. Die Ergebnisse deuten auch darauf hin, dass z. B. die Anbauabstände im Erbsenanbau im Vergleich zu praxisüblichen Empfehlungen vergrößert werden müssen, daneben ergaben sich auch interessante neue Anknüpfungspunkte. Hinsichtlich der Leguminosengesundheit ermöglicht die neu entwickelte Differenzialdiagnose, die Ursache für ggf. auftretende „Leguminosenmüdigkeit“ einzugrenzen bzw. Praxisschläge vor dem Anbau auf Krankheitsrisiken zu testen. Im Projekt konnte außerdem gezeigt werden, dass Grüngutkomposte die Wurzelgesundheit von Erbsen deutlich verbessern können. Es wurden darüber hinaus verschiedene Methoden zur Kompostapplikation zu Körnerleguminosen geprüft und für den Praxiseinsatz optimiert. Neben Grüngutkomposten spielt auch Grünguthäcksel eine wichtige Rolle bei der Nährstoffversorgung von Leguminosen. Oberflächlich leicht eingearbeiteter Grünguthäcksel ist in der Lage, das Wachstum der Kulturpflanzen sowohl durch eine unkrautunterdrückende Wirkung als auch durch Schutz vor Verschlämmung sowie erhöhte Wasserinfiltrationsraten zu verbessern. Die Ergebnisse zum Landtechnikeinsatz zeigen, dass schon geringe Belastungen zu Bodenverdichtungen und damit zu Ertragsrückgängen in Erbsen führen, weshalb Maßnahmen zu Reduzierung des Bodendrucks essenziell sind. Hinsichtlich der beikrautunterdrückenden Wirkung des Gemengeanbaus von Erbsen in Kombination mit Hafer konnte gezeigt werden, dass der Gemengeanbau das erhöhte Beikrautaufkommen bei flachwendender Bodenbearbeitung erfolgreich ausgleichen kann und hinsichtlich der Ertragssicherheit Vorteile mit sich bringt. Nicht zuletzt machte das Projekt auf die Vorteile und Potenziale des Wintererbsenanbaus aufmerksam. Über einen fortlaufenden Wissenstransfer war das Projekt von Beginn an in der landwirtschaftlichen Praxis präsent

Development and analysis of the Soil Water Infiltration Global database

In this paper, we present and analyze a novel global database of soil infiltration measurements, the Soil Water Infiltration Global (SWIG) database. In total, 5023 infiltration curves were collected across all continents in the SWIG database. These data were either provided and quality checked by the scientists who performed the experiments or they were digitized from published articles. Data from 54 different countries were included in the database with major contributions from Iran, China, and the USA. In addition to its extensive geographical coverage, the collected infiltration curves cover research from 1976 to late 2017. Basic information on measurement location and method, soil properties, and land use was gathered along with the infiltration data, making the database valuable for the development of pedotransfer functions (PTFs) for estimating soil hydraulic properties, for the evaluation of infiltration measurement methods, and for developing and validating infiltration models. Soil textural information (clay, silt, and sand content) is available for 3842 out of 5023 infiltration measurements ( ∼ 76%) covering nearly all soil USDA textural classes except for the sandy clay and silt classes. Information on land use is available for 76% of the experimental sites with agricultural land use as the dominant type ( ∼ 40%). We are convinced that the SWIG database will allow for a better parameterization of the infiltration process in land surface models and for testing infiltration models. All collected data and related soil characteristics are provided online in *.xlsx and *.csv formats for reference, and we add a disclaimer that the database is for public domain use only and can be copied freely by referencing it. Supplementary data are available at https://doi.org/10.1594/PANGAEA.885492 (Rahmati et al., 2018). Data quality assessment is strongly advised prior to any use of this database. Finally, we would like to encourage scientists to extend and update the SWIG database by uploading new data to it

Method for fabrication of laser-induced periodic surface structures on vascular stents

Laser-induced periodic surface structures (LIPSS) provide the possibility to functionalize the surface of various materials, which can be used to control the wettability of metal surfaces or influence cell adhesion. LIPSS thus offer great potential for application on implant surfaces if their fabrication process is compatible with standard implant fabrication techniques. Here we demonstrate an easy-to-use two-step fabrication method for stents with different types of LIPSS. The separation between the fabrication of the stent structure and the surface structuring process allows the implementation of any stent structure finishing technique without affecting the LIPSS. The suggested fabrication method may be a step further in implementing laser machining-based surface functionalization in commercial implants

The HIV 5′ Gag Region Displays a Specific Nucleotide Bias Regulating Viral Splicing and Infectivity

Alternative splicing and the expression of intron-containing mRNAs is one hallmark of HIV gene expression. To facilitate the otherwise hampered nuclear export of non-fully processed mRNAs, HIV encodes the Rev protein, which recognizes its intronic response element and fuels the HIV RNAs into the CRM-1-dependent nuclear protein export pathway. Both alternative splicing and Rev-dependency are regulated by the primary HIV RNA sequence. Here, we show that these processes are extremely sensitive to sequence alterations in the 5'coding region of the HIV genomic RNA. Increasing the GC content by insertion of either GFP or silent mutations activates a cryptic splice donor site in gag, entirely deregulates the viral splicing pattern, and lowers infectivity. Interestingly, an adaptation of the inserted GFP sequence toward an HIV-like nucleotide bias reversed these phenotypes completely. Of note, the adaptation yielded completely different primary sequences although encoding the same amino acids. Thus, the phenotypes solely depend on the nucleotide composition of the two GFP versions. This is a strong indication of an HIV-specific mRNP code in the 5 ' gag region wherein the primary RNA sequence bias creates motifs for RNA-binding proteins and controls the fate of the HIV-RNA in terms of viral gene expression and infectivity

The HIV 5′ Gag Region Displays a Specific Nucleotide Bias Regulating Viral Splicing and Infectivity

Alternative splicing and the expression of intron-containing mRNAs is one hallmark of HIV gene expression. To facilitate the otherwise hampered nuclear export of non-fully processed mRNAs, HIV encodes the Rev protein, which recognizes its intronic response element and fuels the HIV RNAs into the CRM-1-dependent nuclear protein export pathway. Both alternative splicing and Rev-dependency are regulated by the primary HIV RNA sequence. Here, we show that these processes are extremely sensitive to sequence alterations in the 5’coding region of the HIV genomic RNA. Increasing the GC content by insertion of either GFP or silent mutations activates a cryptic splice donor site in gag, entirely deregulates the viral splicing pattern, and lowers infectivity. Interestingly, an adaptation of the inserted GFP sequence toward an HIV-like nucleotide bias reversed these phenotypes completely. Of note, the adaptation yielded completely different primary sequences although encoding the same amino acids. Thus, the phenotypes solely depend on the nucleotide composition of the two GFP versions. This is a strong indication of an HIV-specific mRNP code in the 5′ gag region wherein the primary RNA sequence bias creates motifs for RNA-binding proteins and controls the fate of the HIV-RNA in terms of viral gene expression and infectivity

Simulation and experimental study of plasma effects in planar silicon sensors

In silicon sensors high densities of electron-hole pairs result in a change of the current pulse shape and spatial distribution of the collected charge compared to the situation in presence of low charge carrier densities. This paper presents a detailed comparison of numerical simulations with time resolved current measurements on planar silicon sensors using 660~nm laser light to create different densities of electron hole pairs.Comment: Revised Version after peer-revie

Grain legumes and soil fertility - Strategies for a successful cultivation

The German Federal programme on organic farming and other forms of sustainable agriculture developed practical cultivation strategies with the aim of improving soil fertility and plant nutrition. During the five-year project, some new practical knowledge was gained. These findings are listed in the booklet. Reading this guideline should encourage farmers to intensify the cultivation of grain legumes