Untersuchungen zu Controlled Traffic Farming und satellitenbasierten Lenksystemen

Diese Arbeit behandelt Controlled Traffic Farming (CTF) Anbausysteme, bei denen für alle Arbeitsgänge satellitengesteuert immer dieselben Fahrspuren benutzt werden. Lässt sich mit CTF die Belastung des Bodens verringern und die Effizienz von Direktsaat-Anbausystemen steigern? Neben agronomischen und bodenphysikalischen Parametern wurden Auswirkungen von Lenksystemen und Umsetzungsmöglichkeiten von CTF in die Praxis untersucht. Die Analyse einer CTF-Umsetzung unter europäischen Bedingungen mit der Verwendung von Standardmaschinen zeigte, dass sich CTF-Anbausysteme mit den heute zur Verfügung stehenden Maschinen für Dauergrünland, Mähdruschfrüchte und Mais auf kleiner und grösser strukturierten Flächen relativ einfach mechanisieren lassen. Bei Zuckerrüben und Kartoffeln können Kompromisse notwendig sein. Generell erfordern CTF-Anbausysteme eine sorgfältige Planung und Umsetzung in die Praxis. Im dreijährigen Feldversuch (Winterweizen, Wintergerste, Kunstwiese mit Kleegrasmischung) auf einem Lehmboden wurde CTF-Direktsaat mit konventionell zufällig befahrenen Direktsaat- und Pflugverfahren verglichen. Unter CTF zeigte sich eine Differenzierung der nicht, gering und intensiv befahrenen Varianten. Auf dem vorliegenden kompakten Boden mit 1150 mm Jahresniederschlag waren die Unterschiede zwischen den nicht befahrenen Flächen und den mit niedrigem Kontaktflächendruck befahrenen Flächen eher gering. In den nicht befahrenen Flächen entwickelten Eindringwiderstand und Kohlendioxidgehalt der Bodenluft nach drei Jahren signifikant bessere Werte. Bodendichte und Porosität zeigten hingegen keinen eindeutig interpretierbaren Trend. Aufgrund teils suboptimaler Feldaufgänge liess sich keine generelle agronomische Tendenz ableiten. Die intensive Befahrung der Pflegefahrgassen zeigte allerdings klar negative bodenkundliche und planzenbauliche Auswirkungen. Es bietet sich daher an, vor allem für Pflegearbeiten permanent dieselben Fahrspuren zu nutzen. In der Untersuchung zu den Auswirkungen von Lenksystemen zeigten sich signifikante Vorteile von Lenksystemen in einer Verminderung der Fahrerbelastung und einer höheren Lenkgenauigkeit vor allem bei grossen Arbeitsbreiten ohne Spuranreisser. Die meisten anderen Messparameter waren mit Lenksystem leicht vorteilhafter als ohne, unterschieden sich aber nicht signifikant voneinander. Fahrer und naturräumliche Gegebenheiten wie die Schlagform hatten einen wesentlich grösseren Einfluss. Gesamthaft betrachtet erweitert CTF in Kombination mit weiteren Bodenschutzmass-nahmen die Möglichkeiten, Bodenverdichtungen zu vermeiden, den Bedarf an energieintensiver Bodenlocke-rung zu reduzieren und die Entwicklung einer stabileren Bodenstruktur mit höherer Tragfähigkeit zu fördern. Zusammen mit einer an Kultur und Anbausystem angepassten Saatbettbereitung und den in geraden Reihen einfacher durchführbaren mechanischen Pflegemassnahmen ergeben sich gute Voraussetzungen für die Gestaltung agronomisch leistungsfähiger und ökologisch nachhaltiger Anbausysteme.

Fliesslochformen und Gewindefurchen in dünne Bleche und Rohre aus Kupfer und Kupferlegierungen

This thesis in Thermal Flow Drilling and Flowtap in thin metal sheet and pipes of copper and copper alloys had as objectives to know the comportment of copper and copper alloys sheet metal during the Thermal Flow Drill processes with normal tools, to know the best Speed and Feed machine data for the best bushing quality, to known the best Speed for Form Tapping processes and to know the best bush long in pure copper pipes for water solar interchange equipment. Thermal Flow Drilling (TFD) and Form Tapping (FT) is one of the research lines of the Institute of Production and Logistics (IPL) at University of Kassel. At December 1995, a work meeting of IPL, Santa Catarina University, Brazil, Buenos Aires University, Argentine, Tarapacá University (UTA), Chile members and the CEO of Flowdrill B.V. was held in Brazil. The group decided that the Manufacturing Laboratory (ML) of UTA would work with pure copper and brass alloys sheet metal and pure copper pipes in order to develop a water interchange solar heater. The Flowdrill BV Company sent tools to Tarapacá University in 1996. In 1999 IPL and the ML carried out an ALECHILE research project promoted by the DAAD and CONICyT in copper sheet metal and copper pipes and sheet metal a-brass alloys. The normal tools are lobed, conical tungsten carbide tool. When rotated at high speed and pressed with high axial force into sheet metal or thin walled tube generated heat softens the metal and allows the drill to feed forward produce a hole and simultaneously form a bushing from the displacement material. In the market exist many features but in this thesis is used short and longs normal tools of TFD. For reach the objectives it was takes as references four qualities of the frayed end bushing, where the best one is the quality class I. It was used pure copper and a-brass alloys sheet metals, with different thickness. It was used different TFD drills diameter for four thread type, from M-5 to M10. Similar to the Aluminium sheet metals studies it was used the predrilling processes with HSS drills around 30% of the TFD diameter (1,5 – 3,0 mm D). In the next step is used only 2,0 mm thick metal sheet, and 9,2 mm TFD diameter for M-10 thread. For the case of pure commercial copper pipes is used for ¾” inch diameter and 12, 8 mm (3/8”) TFD drill for holes for 3/8” pipes and different normal HSS drills for predrilling processes. The chemical sheet metal characteristics were takes as reference for the material behaviour. The Chilean pure copper have 99,35% of Cu and 0,163% of Zinc and the Chilean a-brass alloys have 75,6% of Cu and 24,0% of Zinc. It is used two German a-brass alloys; Nº1 have 61,6% of Cu, 36,03 % of Zinc and 2,2% of Pb and the German a-brass alloys Nº2 have 63,1% of Cu, 36,7% of Zinc and 0% of Pb. The equipments used were a HAAS CNC milling machine centre, a Kistler dynamometer, PC Pentium II, Acquisition card, TESTPOINT and XAct software, 3D measurement machine, micro hardness, universal test machine, and metallographic microscope. During the test is obtained the feed force and momentum curves that shows the material behaviour with TFD processes. In general it is take three phases. It was possible obtain the best machining data for the different sheet of copper and a-brass alloys thick of Chilean materials and bush quality class I. In the case of a-brass alloys, the chemical components and the TFD processes temperature have big influence. The temperature reach to 400º Celsius during the TFD processes and the a-brass alloys have some percents of Zinc the bush quality is class I. But when the a-brass alloys have some percents of Lead who have 200º C melting point is not possible to obtain a bush, because the Lead gasify and the metallographic net broke. During the TFD processes the recrystallization structures occur around the Copper and a-brass alloy bush, who gives more hardness in these zones. When the threads were produce with Form Tapping processes with Flowtap tools, this hardness amount gives a high limit load of the thread when hey are tested in a special support that was developed for it. For eliminated the predrilling processes with normal HSS drills it was developed a compound tool. With this new tool it was possible obtain the best machining data for quality class I bush. For the copper pipes it is made bush without predrilling and the quality class IV was obtained. When it is was used predrilling processes, quality classes I bush were obtained. Then with different HSS drill diameter were obtained different long bush, where were soldering with four types soldering materials between pipes with 3/8” in a big one as ¾”. Those soldering unions were tested by traction test and all the 3/8” pipes broken, and the soldering zone doesn’t have any problem. Finally were developed different solar water interchange heaters and tested. As conclusions, the present Thesis shows that the Thermal Flow Drilling in thinner metal sheets of cooper and cooper alloys needs a predrilling process for frayed end quality class I bushings, similar to thinner sheets of aluminium bushes. The compound tool developed could obtain quality class I bushings and excludes predrilling processes. The bush recrystalization, product of the friction between the tool and the material, the hardness grows and it is advantageous for the Form Tapping. The methodology developed for commercial copper pipes permits to built water solar interchange heaters.

Artificial micro RNA system in Dictyostelium discoideum

Dictyostelium discoideum is a social amoeba that serves as a model system for RNA interference and related mechanisms. Its position between plants and animals enables evolutionary snapshot of mechanisms and protein machinery involved in investigated subjects. MiRNAs are small regulatory RNAs that are evolutionary conserved and present in animals, plants, viruses and some prokaryotes. They have roles in development, cell growth and differentiation, apoptosis and their miss-regulation is associated with many diseases such as cancer, neurodegenerative disorders and diabetes. Recently, through sequencing of DNA libraries miRNAs have been discovered in D. discoideum. In this work, it has been shown that heterologues miRNA let-7 can be expressed and processed in D. discoideum. Expression of let-7 miRNA in social amoeba resulted in a strong developmental phenotype suggesting an overload of the processing/silencing system or/and endogenous targets. The various effects on prel-7 strain have been observed and characterized, serving as a background for postulation of miRNA roles. An artificial miRNA system has been established and imposed to D. discoideum, showing that miRNAs in Dictyostelium could mediate gene expression on the level of mRNA stability and on the posttranscriptional level. Furthermore, presence of translational inhibition as a type of gene control was shown for the first time in this organism. Due to it new structures representing co-localities of miRNA and target mRNA have been detected. Taken together, this work shows functional artificial miRNA system and postulates roles of endogenous small RNA in social amoeba.

Unveiling the components of the signaling pathway between endosomes and the phagocytic uptake machinery in Dictyostelium discoideum

The soil amoebae Dictyostelium discoideum take up particles from their environment in order to obtain nutrition. The particle transits through the cell within a phagosome that fuses with organelles of different molecular compositions, undergoing a gradual degradation by different sets of hydrolytic enzymes. Griffiths’ concept of “phagosome individuality” predicts signaling from phagosomes into the cytoplasm, which might regulate many aspects of cell physiology. The finding that Dictyostelium cells depleted of the lysozyme AlyA or over-expressing the esterase Gp70 exhibit increased uptake of food particles, led to the postulation of a signaling cascade between endocytic compartments and the cytoskeletal uptake machinery at the plasma membrane. Assuming that Gp70 acts downstream of AlyA, gene-expression profiling of both mutants revealed different and overlapping sets of misregulated genes that might participate in this signaling cascade. Based on these results, we analyzed the effects of the artificial misregulation of six candidate genes by over-expression or negative genetic interference, in order to reconstruct at least part of the signaling pathway. SSB420 and SSL793 were chosen as candidates for the first signaling step, as they were up-regulated in AlyA-null cells and remained unaltered in the Gp70 over-expressing cells. The over-expression of SSB420 enhanced phagocytosis and raised the expression levels of Gp70, supporting its involvement in the signaling pathway between AlyA and Gp70 as a positive regulator of phagocytosis. However, this was not the case of cells over-expressing SSL793, as this mutation had no effects on phagocytosis. For the signaling downstream of Gp70, we studied four commonly misregulated genes in AlyA-depleted and Gp70 over-expressing cells. The expression levels of SLB350, SSB389 and TipD were lower in both mutants and therefore these were assumed as possible candidates for the negative regulation of phagocytosis. Cells depleted of SLB350 exhibited an increased phagocytic activity and no effect on Gp70 expression, proving its participation in the signaling pathway downstream of Gp70. Unlike SLB350, the disruption of the genes coding for SSB389 and TipD had no effects on particle uptake, excluding them from the pathway. The fourth candidate was Yipf1, the only gene that was commonly up-regulated in both mutants. Yet, the artificial over-expression of this protein had no effects on phagocytosis, so this candidate is also not included in the signaling pathway. Furthermore, localizing the products of the candidate genes within the cell helped unveiling several cellular organelles that receive signals from the phagosome and transduce them towards the uptake machinery.