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- Dahlin, Andreas, 1980
(författare)
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Nanoplasmonic Biosensors compatible with Artificial Cell Membranes
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Within life science, there is currently an intense search for novel techniques that enable efficient and reliable analysis of biomolecular interactions. Such methods have future applications within medical diagnostics and drug development, as well as within proteomic research in general. Lately, several concepts have emerged that are based on monitoring molecular binding to surfaces via optical, mechanical or electrical signal transduction. In particular, the plasmons associated with metallic nanoparticles are of interest since they offer a convenient way to monitor biomolecular interactions, also in a miniaturized format, by optical spectroscopy.This thesis describes the development of a biosensor based on the optical properties of nanoscale apertures in continuous metal films. The fabrication and characterization of the nanostructure is described, as well as surface modification protocols based on thiol chemistry for material-specific functionalization. In addition, an experimental setup for spectroscopy is presented together with data analysis algorithms for minimizing noise.It is emphasized that, from an experimental sensing perspective, nanoholes and nanoparticles have essentially the same plasmonic properties. However, the nanoholes offer several advantages because of the fact that the structure is physically different. In particular, it is shown how various artificial cell membranes can be spontaneously formed inside nanoholes. This makes the sensor compatible with studies of processes related to biological membranes. In this context, membrane-bound proteins are of special interest since they constitute a third of our genome and represent the target of half of the most common medical drugs. Potential future applications of the artificial membranes on the plasmonic nanostructures are discussed, with focus on probing transport across the membrane.
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- Dahl, Ingolf, 1950
(författare)
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How to measure the Mueller matrix of liquid-crystal cells
- 2001
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Ingår i: Meas. Sci. Technol.. - 0957-0233. ; 12, s. 1938-1948
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Tidskriftsartikel (refereegranskat)abstract
- The Mueller matrix is the transfer matrix in the Stokes algebra that describes the polarization of natural light. This matrix is very versatile for the task of characterizing the optical properties of liquid-crystal cells, since it can be used for comparison with theoretical calculations, the determination of material parameters and the modelling of the cell as an optical building block for technological use. We have constructed a Mueller-matrix spectrometer, with the ability to perform fast, dynamic measurements of the Mueller matrix of small areas of liquid-crystal cells throughout the visible range. To illustrate the potential of the instrument, dynamic measurements on a ferroelectric-liquid-crystal cell are presented and analysed. The optical measurements indicate that there is an asymmetry between the up and the down state, tilted smectic layers and polarization reversal initiated at the boundaries.
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| 6. |
- Desmaris, Vincent, 1977, et al.
(författare)
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Microfabrication Technology for All-Metal Sub-mm and THz Waveguide Receiver Components
- 2008
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Ingår i: In Proceedings of The 19th International Symposium on Space Terahertz Technology, Groningen, 28-30 April, 2008, ed. W. Wild, Space Research Organization of the Netherlands (SRON). ; part I, s. 342-345
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Konferensbidrag (refereegranskat)abstract
- A novel technology for manufacturing of micromachined all-metal waveguide circuits and structures for the frequency band from 200 up to 7000 GHz (Sub-Millimeter and THz) is presented. The waveguide circuits are formed using metal electroplating with preceding sputtering of a thin metal film seed layer over a photo-lithographically patterned thick SU-8 photo-resist. The process provides possibility of making 3-dimensional structures via facilitating of multi-level (layered) designs. Surface roughness of the THz waveguide structure was demonstrated to be below 0.1 µm. This technology was used to build a state-of-the art waveguide balanced 1.3 THz Hot Electron Bolometer mixer and other application for radio astronomy instrumentation.
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- Mamontov, Eugen, 1955, et al.
(författare)
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Asymptotic trajectory matching in self-navigation of autonomous manless interceptors: Nonsearch method and a formulation of the functional optimization of the stability of random systems
- 2006
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Ingår i: Proc. 5th MATHMOD Vienna Conf., 8-10 February, 2006 (Vienna Univ. of Technol., Vienna, Austria). - 3901608303 ; 2
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Konferensbidrag (refereegranskat)abstract
- In the field of self-navigation autonomous manless robots there is a noticeable interest to the robot-based target-interception problem. The interceptor trajectory is usually determined by search-based optimization algorithms. In contrast to this, the present work treats the interception as asymptotic trajectory matching and introduces a nonsearch method for the interceptor trajectory. This method is substantially simpler than the well-known proportional navigation and requires very limited computing resources. The latter feature makes the proposed method especially suitable to the interceptors based on embedded onboard computers and civil applications. An example of the latter discussed in the work is the protection of the infrastructure components against intended or unintended attacks. In a general case when parameters of the interceptor are random, the new method leads to a formulation of a new problem in stochastic optimization, namely the functional optimization of (the so-called targetal) stability of the interceptor trajectory. Certain aspects of a practical implementation of the new systems are analyzed. The work proposes the basic physical principle and schemes for innovative sensors which can make the interceptors truly autonomous, in particular, fully GPS-free. A list of the fundamental and applied topics for future research is also suggested.
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| 8. |
- Alkebro, Jesper, et al.
(författare)
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Modeling high-energy ball milling in the alumina-yttria system
- 2002
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Ingår i: Journal of Solid State Chemistry. - : Elsevier BV. - 0022-4596 .- 1095-726X. ; 164:1, s. 88-97
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Tidskriftsartikel (refereegranskat)abstract
- Experimental results from high-energy ball milling of alumina-yttria powder mixtures have been analyzed with models collected from the literature. Depending on the milling conditions, either there is formation of an intermediate phase in the alumina-yttria system (yttrium aluminum perovskite, YAP), or the sample becomes mostly amorphous. Variations due to milling tool material can be accounted for by local models based on the Hertzian theory of elastic bodies, but the effects of changing mills are poorly accounted for by published models. Therefore, the concept of an impact frequency distribution over the energy spectrum is introduced as a tool for studying the characteristics of the mills. The pressure on the powder trapped between two colliding bodies has been found to be the factor deciding the outcome of the process. The threshold behavior of the system yields an amorphous structure for low pressures, and formation of YAP when impact pressures exceed the threshold value.
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- André, Alann, et al.
(författare)
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Finite element delamination study of a notched composite plate under flexural loads
- 2009
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Ingår i: ICCM-17, 17th International Conference on Composite Materials, Edinburgh, UK. - London : IOM Communications.
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Konferensbidrag (refereegranskat)abstract
- The delamination process in notched composite plates under flexural loading has been investigated using finite element analysis. Cohesive elements implemented in the commercial finite element package ABAQUS have been used in the region around the drilled-hole, and positioned between layers where delamination was observed during experiments presented in an accompanying paper. The delamination initiation and subsequent propagation was studied between the layers at the tension side separately and simultaneously. For all FE models, the load displacement curve was in good agreement with the one from experiments. However, the amount of damage reported from the fractography study was more extensive than that predicted by the models. Finally, it was shown that the models with only one cohesive layer show significantly different results to that of the model with four cohesive layers in terms of size of the degradation area.
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