Development of a Flaw Tolerant Enhanced Safe Life Concept for Composite Parts in Turbo-Engines

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Separating hyperfine from spin-orbit interactions in organic semiconductors by multi-octave magnetic resonance using coplanar waveguide microresonators

Separating the influence of hyperfine from spin-orbit interactions in spin-dependent carrier recombination and dissociation processes necessitates magnetic resonance spectroscopy over a wide range of frequencies. We have designed compact and versatile coplanar waveguide resonators for continuous-wave electrically detected magnetic resonance, and tested these on organic light-emitting diodes. By exploiting both the fundamental and higher-harmonic modes of the resonators we cover almost five octaves in resonance frequency within a single setup. The measurements with a common pi-conjugated polymer as the active material reveal small but non-negligible effects of spin-orbit interactions, which give rise to a broadening of the magnetic resonance spectrum with increasing frequency

Experimental Evaluation of Ultrasonic Simulation Techniques in Anisotropic Material

The high performance of the available computer technology provides the possibility to simulate the real life for ultrasonic inspections in terms of primary ultrasonic data like rf-time signals. For isotropic material codes like Generalized Point Source Synthesis (GPSS) or Elastodynamic Finite Integration Technique (EFIT) and the theoretical predictions correlate well with experimental results. Recently, the codes mentioned above have been extended to operate also in anisotropic material. In a first step the codes GPSS and EFIT have been expanded to work in materials of parallel oriented columnar grain structure with transversely isotropic symmetry. In order to verify these codes a set of experiments was carried out on weld metal pads and on welds of defined grain structure. Radiation, propagation, reflexion on boundaries and interaction of the sound field with defects for the modes “through transmission” and “pulse echo” were simulated and compared with the experiment

In search of a combined brucellosis and tuberculosis vaccine for cattle

Bovine brucellosis is caused by Brucella abortus. The bacterial pathogen causes economic losses because it induces abortion in cattle. Vaccination of calves with live B. abortus strain 19 induces a certain level of protection but induces persistent antibodies against cell envelope lipopolysaccharide that make it difficult to Distinguish Infected from Vaccinated Animals (DIVA). Live vaccine B. abortus strain RB51 was developed to eliminate such interfering antibodies and therefore, facilitate the differentiation of infected from vaccinated animals and help in the eradication of the disease. Vaccination with strain RB51 induces levels of protection similar to strain 19 but neither of the two vaccines give complete protection. We have been working to enhance protection induced by strain RB51 vaccine. Protective Brucella antigens can be over-expressed in strain RB51 by introducing a plasmid containing the leuB gene and the genes encoding such antigens. To avoid the expression of antibiotic resistance genes, we produced a leuB deficient strain RB51 and introduced a plasmid containing the leuB gene and the genes to be over-expressed. This new strain maintains the plasmid and has induced significantly high protection levels in mice. In addition, it allowed the construction of an RB51 vaccine strain able to express Mycobacterium bovis protective antigens so that the vaccine could protect against brucellosis and tuberculosis simultaneously

Ac magnetic susceptibility of a molecular magnet submonolayer directly patterned onto a microSQUID sensor

We report the controlled integration, via Dip Pen Nanolithography, of monolayer dots of ferritin-based CoO nanoparticles (12 Bohr magnetons) into the most sensitive areas of a microSQUID sensor. The nearly optimum flux coupling between these nanomagnets and the microSQUID improves the achievable sensitivity by a factor 100, enabling us to measure the linear susceptibility of the molecular array down to very low temperatures (13 mK). This method opens the possibility of applying ac susceptibility experiments to characterize two-dimensional arrays of single molecule magnets within a wide range of temperatures and frequencies.Comment: 4 pages 3 figure

Transformation Optics for Plasmonics

A new strategy to control the flow of surface plasmon polaritons at metallic surfaces is presented. It is based on the application of the concept of Transformation Optics to devise the optical parameters of the dielectric medium placed on top of the metal surface. We describe the general methodology for the design of Transformation-Optical devices for surface plasmons and analyze, for proof-of-principle purposes, three representative examples with different functionalities: a beam shifter, a cylindrical cloak and a ground-plane cloak.Comment: 15 pages, 3 figure

Amorphous silicon thin films: The ultimate lightweight space solar cell

Progress is reported with respect to the development of thin film amorphous (alpha-Si) terrestrial solar cells for space applications. Such devices promise to result in very lightweight, low cost, flexible arrays with superior end of life (EOL) performance. Each alpha-Si cell consists of a tandem arrangement of three very thin p-i-n junctions vapor deposited between film electrodes. The thickness of this entire stack is approximately 2.0 microns, resulting in a device of negligible weight, but one that must be mechanically supported for handling and fabrication into arrays. The stack is therefore presently deposited onto a large area (12 by 13 in), rigid, glass superstrate, 40 mil thick, and preliminary space qualification testing of modules so configured is underway. At the same time, a more advanced version is under development in which the thin film stack is transferred from the glass onto a thin (2.0 mil) polymer substrate to create large arrays that are truly flexible and significantly lighter than either the glassed alpha-Si version or present conventional crystalline technologies. In this paper the key processes for such effective transfer are described. In addition, both glassed (rigid) and unglassed (flexible) alpha-Si cells are studied when integrated with various advanced structures to form lightweight systems. EOL predictions are generated for the case of a 1000 W array in a standard, 10 year geosynchronous (GEO) orbit. Specific powers (W/kg), power densities (W/sq m) and total array costs ($/sq ft) are compared

General Relativity in Electrical Engineering

In electrical engineering metamaterials have been developed that offer unprecedented control over electromagnetic fields. Here we show that general relativity lends the theoretical tools for designing devices made of such versatile materials. Given a desired device function, the theory describes the electromagnetic properties that turn this function into fact. We consider media that facilitate space-time transformations and include negative refraction. Our theory unifies the concepts operating behind the scenes of perfect invisibility devices, perfect lenses, the optical Aharonov-Bohm effect and electromagnetic analogs of the event horizon, and may lead to further applications

Transformation bending device emulated by graded-index waveguide

We demonstrate that a transformation device can be emulated using a gradient-index waveguide. The effective index of the waveguide is spatially varied by tailoring a gradient thickness dielectric waveguide. Based on this technology, we demonstrate a transformation device guiding visible light around a sharp corner, with low scattering loss and reflection loss. The experimental results are in good agreement with the numerical results.Comment: This paper is published at Optics Express 20, 13006 (2012