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Polyelektrolyteigenschaften der gelmatrixbildenden Komponenten von Biofilmen - Polyelectrolyte properties of the gel-matrix building components of biofilmsKenning, Arnd 01 October 2003 (has links)
Goals of this study are to point out strategies to influence the gel-matrix building components of biofilms. One well characterised component of the extracellular polymeric substances (EPS) of the bacterial strain Pseudomonas aeruginosa SG81 is the alginate AlgSG81. AlgSG81 is one main component of EPS and thus of the gel-matrix, too. AlgSG81 is completely dissociated in aqueous solution and therefore a strong polyelectrolyte (PEL). By means of computation with OSF-theory and validation via viscosity measurements the conformation of AlgSG81-chains in aqueous solution at screened and not screened conditions is that of a coil over a large concentration regime. By addition of tetramethylurea (TMU) to aqueous solutions of AlgSG81 the formation of a physical network (gel) is observed. Different empirical and theoretical approaches to characterise PEL were improved and experimental verified.
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Erstellung und Validierung einer kombinierten NIR/Raman-Bibliothek zur Identitätskontrolle organischer und anorganischer Substanzen - Creation and validation of a combined NIR/Raman-library for identity control of organic and inorganic substancesMandal, Oliver 02 October 2001 (has links)
Due to legal requests in future the identity control of products will not only be required in pharmaceutical industry but also in chemical industry. Therefore the demands on the analytical methods are very high. The company Merck realized an identity control tool by combining NIR and Raman spectroscopy. This Tool is suited for identification of a broad range of organic and inorganic substances. In this work different chemometric methods and data pretreatments were tested. The NIR and the Raman library have been optimized and the validation results visualized. Alternatives as binary coding and wavelet transformation, which lead to data compression at the same time, were tested
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Strukturierung und elektrische Eigenschaften von Gasphasen-generierten PbS Nanokristall-Filmen / Structuring and electronic properties of gasphase-generated PbS nanocrystal filmsOtten, Frank 07 October 2005 (has links)
Nanocrystal films may be used as detector material in sensors, as charge storage or conducting channels in devices. In this work lead sulphide (PbS) nanocrystals are generated in the gas-phase and deposited onto substrates forming nanocrystal films. A technology is developed for lateral structuring of these films on the substrate and to process them further by microelectronic standard processes. The pattern of the nanocrystal film is scaled down by several hundreds of nanometers compared to the used photoresist mask pattern. The responsible mechanism is found by consideration of physical mechanisms and usage of a trajectory simulation program. For basic electrical investigation a system is designed for production of nanocrystal films and electrical characterization under clean conditions. Noise measurements and I-V characterizations are performed. Both, single charge transport and charge transport through the interface of nanocrystal film and substrate have been found. The volume of the nanocrystal film is for the current transport not important. PbS nanocrystal films can be used in future devices for definition of high resolution current paths. Current designs can be used to downscale the device patterns without applying high resolution lithography. The parallel process technology with optical lithography still can be used to implement the films into microelectronic devices. With the trajectory simulation program the geometry can be predicted. The developed technology and the results can be transmitted to other material systems.
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Molekulare Mangan-,Eisen- und Cobalt-Komplexe mit neuartigen Metall-Chalcogen-Gerüsten - Molecular manganese-, iron- and cobalt-complexes with novell metal-chalcogenides frameworksSeidel, Renate Magdalene 10 October 2001 (has links)
The possibility of synthesis of (poly-)chalcogenide and chalcogenolate ions to manganese, iron and cobalt was expanded with the introduction of the donor ligand carbon monoxide. The metal atoms get than greater coordination numbers. So it was possible to synthesise new metal frameworks, p. e. Co11E7 in the complexes [Ph4P]2[Co11Se7(CO)10] and [Ph4P]2[Co11Te7(CO)10], in which the cobalt atoms built a inner centred pentagonal prism. In the examined reaction systems Mn2(CO)10/Na2Sex/Kat, Fe(CO)5/Na2Ex/Kat and Co2(CO)8/Na2Ex/Kat (E = Se or Te; x = 1 or 2; Kat = Ph4PCl or PPNCl) succeeded the synthesis of [Co6Se8(CO)6]-/2-anions as first anionic clusters of the M6E8L6 class. The difference between the new [Co6Se8(CO)4]- anion and the M6E8L6-complex class is the extraordinary compressed Co6-oktaeder and considerable shorter Co-Co-distances. In addition to the higher mentioned compounds it was possible to synthesise and characterize unambiguous with the aid of single crystal x-ray crystallography the following complexes: [Ph4P]2[Fe3Te(CO)9]; [Ph4P][Fe3EH(CO)9] für E=Se,Te; [Ph4P]2 [Fe4Te2(CO)14]; [Ph4P]2 [Fe6Se6(CO)12]; [Ph4P]2 [Mn3Se2(CO)9]. Worth mentioning is also the unusual square pyramidal coordination of the manganese atom in the [Ph4P][Mn(CO)5] crystal. Until now were only penta carbonyl complexes known with a trigonal bipyramidal coordination.
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Thermodynamische Eigenschaften semirigider Polymere und deren Anwendung in faseroptischen Detektoren - Thermodynamic properties of semirigid polymers and their applications in fibre optical detectorsWoelke, Ralf 12 October 2001 (has links)
In the following thesis the thermotropic phase transition behaviour and structure-property-relations of semiflexible polyesters were investigated. These materials can be used in fibre optical blood-pressure sensors as resonator materials in a Fabry-Perot-Interferometer. PVT-measurements were carried out to determine the thermodynamic parameters alphaV(T) and kappa(P), and the validity of the Ehrenfest equations at glass transition temperatures was verified. These latter investigations showed no thermodynamic second order transition. By using alphaV(T) and kappa(P) for the calculation of the resonator-length-difference, the temperature- and pressure behaviour of the investigated polyesters was simulated. This simulation showed that small variations in the resonator length from increasing pressure agrees with the empirically determined values. An increasing number of methylene groups in the sidechain of the spacer molecule resulted in decreased melting- and glass transition temperature, which revealed the possibility to prepare thin polymer-films with 5-10 micrometer in diameter at low temperatures.
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Dynamical Behaviour of Small Molecules Clathrated in Syndiotactic Polystyrene: a Solid State Deuterium NMR Investigation - Dynamisches Verhalten kleiner Molekülen innerhalb der Hohlräume von syndiotaktischem Polystyrol: eine Deuterium-Festkörper-NMR-UntersuchungTrezza, Elena 19 November 2003 (has links)
The crystalline regions of the δ-form of syndiotactic polystyrene (s-PS) contain cavities in which certain small molecules can be absorbed. The mobility of six perdeuterated molecules: benzene, toluene, chloroform dichloromethane, 1,2-dichloroethane and 1,2-dibromoethane, present as a guest in these cavities, has been investigated via 2H NMR spectroscopy. For all samples the motional behavior of the molecules absorbed in the amorphous phase of the polymer differs from that shown by the molecules clathrated in the crystalline phase. The motion of all six molecules in the amorphous phase is approximately isotropic at a temperature T = 298 K or higher, but severely anisotropic when the molecules are included in the crystalline phase. The dynamical behavior of each solvent hosted in the crystalline phase of s-PS has been investigated by comparing spectra obtained by simulation of the effect of a certain molecular rotation on the 2H spectra with the experimental spectra.
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Vertikale Wanderwellenmodulatoren auf Quantenfilmbasis für die optische Informationsverarbeitung - Vertical travelling-wave modulators using quantum-well material for optical information processingWingen, Georg 12 October 2001 (has links)
The vertical optical travelling-wave modulator represents a new high-frequency element for optical data processing. The modulator is designed for a wavelength of 1200 nm and combines the layered structure of vertical optical modulators based on pseudomorphic InGaAs/GaAs quantum-wells with microwave lines from the MMIC technology. The quantum confined Stark effect is used to modulate the optical signal. The multiple quantum-well structure is embedded into an asymmetrical Fabry-Perot resonator built from a Bragg reflector and an aluminum layer to increase the electrooptical effect. The modulators produces a reflectivity change of 0,28. Large scale travelling-wave modulators are capable of critical frequencies higher than 40 GHz. By varying the width of the central conductor of the microwave line, the slow-wave factor could be varied experimentally between 4.8 and 12,7. The applied microwave produces a modulation lattice along the microwave line which can be used in a high frequency beam-steering element for optical information processing
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Verkapselung von organischen Substraten in Polycyanoacrylat-Nanokapseln - Encapsulation of Organic Substrates in Polyalcylcyanoacrylate NanocapsulesAltinbas, Neslihan 21 November 2003 (has links)
In this work, nanocapsules were synthesized from n-butylcyanoacrylat (BCA) and characterized under variation of kind and quantity of the synthesis components. The influences of the quantity variations were interpreted, using a reduced and a complete factorized experimental design. Hereby, the properties of the capsules have been specified, such as width, width distribution, density, wall thickness and morphology of the capsule. For the verification of the construction of the capsules and their characterization different analytical methods have been used, i.e. TGA, TEM, AFM, AUZ and DLS. In addition, Zeta potentials have been measured and taken into consideration.
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Economic Relations Between Germany and Japan : an Analysis of Recent Data <br>Duisburger Papiere zur Ostasienwirtschaft ; 61 (2002)Pascha, Werner 22 October 2002 (has links)
The author takes a close look at bilateral German-Japanese trade and direct investment data, employing various techniques (intensity indicators, RCA, intra-industry trade). It turns out that German-Japanese trade and FDI links are indeed rather limited, as has frequently been stated. A number of somewhat surprising pieces of evidence do emerge, though. For competitive industries and with respect to emerging opportunities, the bilateral figures do show a healthy performance
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Institutionenökonomische Anmerkungen zur Einbettung von Korruption in das Ordnungssystem chinesischer Guangxi-Netzwerke <br>Duisburger Papiere zur Ostasienwirtschaft ; 60 (2001)Schramm, Matthias ; Taube, Markus 22 October 2002 (has links)
In jüngster Zeit ist das Phänomen der Korruption in der VR China wieder verstärkt in das Blickfeld gerückt. Wie allen ökonomischen Austauschbeziehungen, so stellt sich auch korrupten Transaktionen das Problem der Absicherung derselben gegen opportunistisches Verhalten. In diesem Beitrag werden die chinesischen Guanxi-Netzwerke als eine sowohl in funktionaler als auch transaktionstheoretischer Hinsicht optimale Lösung dieses Ordnungsproblems identifiziert. Dies resultiert daraus, dass Guanxi-Netzwerke es vermögen, durch die Bindung von Investitionen in social capital stark risikobehaftete Austauschbeziehungen in sich selbst durchsetzende Verträge zu transformieren. Die durch den forcierten Aufbau eines Rechtssystems in der VR China aufgeworfene Frage, ob hierdurch Guanxi-Netzwerke verdängt und somit letztlich auch das Phänomen der Korruption zurückgeführt werden könnte, wird abschlägig beantwortet. Eine Analyse der einen derartigen institutionellen Wandlungsprozess determinierenden Faktoren institutionelle L eistungsfähigkeit, Kostenstrukturen, Pfadabhängigkeit und embeddedness zeigt, dass eine substantielle Verdrängung der Guanxi-Netzwerke auch bei weiterer Stärkung des chinesischen Rechtssystems nicht zu erwarten ist. Von dieser Seite her kann also kein Impuls zur Reduzierung des Korruptionsphänomens in der VR China erwartet werden.
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