The composition of volatile extractives from the wood of Juniperus excelsa, Juniperus foetidissima and Juniperus oxycedrus

J. excelsa , J. foetidissima and J. oxycedrus. Among the compounds the monoterpenes exist in minor amounts while the sesquiterpenes including their oxygenated members as well as sesquiterpene alcohols consist of the majority of the whole substances. The existence of some compounds of the oils might be attributes of the species and their sap- and heartwood. On the other side though notable differences, the essential oils of Turkish juniper woods resemble the commercial cedar wood oils.

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Die Zusammensetzung der flüchtigen Extraktstoffe im Holz von Juniperus foetidissima und Juniperus oxycedrus

J. excelsa , J. foetidissima und J. oxycedrus. Monoterpene bilden einen geringen Anteil der Extraktstoffe. Der Hauptteil besteht aus Sesquiterpenen mit deren Oxydationsprodukten. Das Vorkommen einiger der ?le k?nnte charakteristisch sein für die jeweilige Art bzw. deren Splint- und Kernholz Allerdings gleichen diese ?le, trotz geringer Unterschiede, den wesentlichen ?lbestandteilen von Kommerziellen Zedernh?lzern.

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This work was supported by the research found of the Istanbul University. Project nr: 1335/280799.     

Mlcrolasers based on silica microspheres

Light can be confined efficiently in the high-Q, small-volume whispering-gallery-modes observed in silica microspheres. By coupling these microspheres to eroded optical fibers and fiber tips, direct mapping of the whispering-gallery modes has been achieved and the mode numbers have been assessed. The properties of these modes have allowed us to obtain laser action with very low thresholds in Nd-doped silica microspheres. Further projects in the field of non-linear optics and cavity quantum electrodynamics are described.     

Potential science-technology spillovers in regions: An insight on geographic co-location of knowledge activities in the EU

This article depicts some features of the geography of science and technology outputs in the EU, with a particular attention to regional “co-location” of these two pillars of the “knowledge-based society”. Economists have, for a decade, paid great attention to local “spillovers” stating that industrial firms often draw advantages from the presence of nearby academic centres. The presence in the same areas of strong academic and technological resources is both a condition and a result of science-technology interactions. Concentrating on publications and patents as proxies of the science and technology level in regions, we built a typology of regions according to their commitment to the two knowledge-base activities and then analysed the co-locations of science and technology from several points of view. A fine-grain lattice, mainly based on standard Nuts3 level, was used. Co-location, at the EU level, is not a general rule. A strong potential for spillover/ interaction does exist in the top-class regions which concentrate a high proportion of European S and T output. But for regions with a small/medium level of S&T activity, a divergence of orientations appears between a science-oriented family and a technology-oriented family, indicating an imbalance between local S and T resources. If we look at the S-oriented regions, whilst controlling for underlying factors, such as population and regional economic product, a significant geographic linkage between T and S appears. This suggests a trajectory of science-based technological development. A careful examination of S&T thematic alignments and specialisation is necessary to develop the hypothesis that fostering academic resources could increase the technological power along a growth path. This revised version was published online in August 2006 with corrections to the Cover Date.     

Experimental analysis of corner-fed printed square patch antennas

An experimental analysis is developed for the corner-fed printed square patch antenna, taking into account the width of the feeding junction and the proximity of the microstrip feedline. New accurate design relations for resonance frequency and input impedance are deduced, directly usable for the computer aided design of printed antenna arrays.<>     

Efficient reconstruction from non-uniform point sets

We propose a method for non-uniform reconstruction of 3D scalar data. Typically, radial basis functions, trigonometric polynomials or shift-invariant functions are used in the functional approximation of 3D data. We adopt a variational approach for the reconstruction and rendering of 3D data. The principle idea is based on data fitting via thin-plate splines. An approximation by B-splines offers more compact support for fast reconstruction. We adopt this method for large datasets by introducing a block-based reconstruction approach. This makes the method practical for large datasets. Our reconstruction will be smooth across blocks. We give reconstruction measurements as error estimations based on different parameter settings and also an insight on the computational effort. We show that the block size used in reconstruction has a negligible effect on the reconstruction error. Finally we show rendering results to emphasize the quality of this 3D reconstruction technique.     

Synthesis and characterization of novel polyacrylate-clay sol-gel materials

Organo-functional silanes which were able to form chemical bonds with kaolinite and could also have an affinity to the materials of concern here, were studied by the sol-gel process. Polymethacrylate with trialkoxy silyl functional groups were prepared, hydrolysed and co-condensed with kaolinite. The progress of the hydrolysis, which proceeded very slowly, was followed by Karl-Fischer titration. Thermal behavior was investigated by differential thermal analysis. The extent of the reaction leading to network formation was qualitatively followed by Fourier transform-infrared spectroscopy and X-ray diffraction. Free-radical polymerization was carried out ultrasonically in the presence of a catalyst. Trimethoxy silane end-capped silane was found to be covalently bonded to kaolinite. The copolymers, with various amounts of kaolinite, were then hydrolysed and co-condensed in the presence of a catalyst to yield sol-gel materials which have a controllable combination of properties of both the polymer and kaolinite.     

WO3 pillar-type and helical-type thin film structures to be used in microbatteries

In the present study WO₃ thin films were deposited by sputtering onto ITO glass, W/ITO and Si substrates by using the glancing angle deposition (GLAD) technique, with the objective of applying these materials in electrochemical intercalation devices. The thin films microstructure and electrochemical behavior were determined through scanning electron microscopy (SEM) and cycling at constant current with potential limitation. By mainly adjusting the substrate holder speed rotation, pillar-type and helical-type structures were obtained under high and low speed rotation levels, respectively. The electrochemical results showed that the best charge capacity performance was obtained for the WO₃/W/ITO films with pillar-type structures, which are more porous.