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1.
Y. Bassiakos A. Athanassiou S. Roussiakis G. Theodorou 《Journal of Radioanalytical and Nuclear Chemistry》1992,158(2):239-250
Five Upper Miocene fossil Hipparion molars were studied for U-distribution by Fission Track. U uptake has reached the whole mass of the teeth and no saturation fronts seem to occur in the interior layers. Mean U-concentration in dentine, cement and enamel was 157, 139 and 78 ppm, respectively. Uenamel/Udentine 0.5 is considerably higher than 0.1 reported in the past for Upper-Quaternary mammoth teeth. These features are disadvantageous for ESR-dating in Hipparion enamel, although a long-lived signal (g=2.0018) is apparent. Leaching phenomena occur in the outer regions of these teeth. Inner enamel folding seems to have hindered a more uniform U-distribution in the teeth. 相似文献
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A. Athanassiou K. Lakiotaki V. Tornari S. Georgiou C. Fotakis 《Applied Physics A: Materials Science & Processing》2003,76(1):97-100
This work examines volume changes at the sub-micron scale, induced photochemically in polymeric matrices doped with photochromic
molecules. To achieve this, spiropyran is employed as a photochromic molecule embedded in polyethylmethacrylate-co-methylacrylate (PEMMA) matrices. Spiropyran can be reversibly interconverted to merocyanine, its coloured isomer, by irradiation at 248 nm
and 532 nm, correspondingly. It is demonstrated that the interconversion between the two forms activates volume changes in
the polymer matrix. To this end, off-axis reflection holographic interferometry is employed as a sensitive probe of the induced
volume changes. This scheme provides a novel method for controlling sub-micron volume changes reversibly, as required in several
microactuator designs.
Received: 17 April 2002 / Accepted: 18 April 2002 / Published online: 10 September 2002
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ID="*"Corresponding author. Fax: +30-810/391-318, E-mail: nassia@iesl.forth.gr 相似文献
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M.I. Lygeraki E. Tsiranidou S.H. Anastasiadis C. Fotakis D. Pisignano R. Cingolani A. Athanassiou 《Applied Physics A: Materials Science & Processing》2008,91(3):397-401
We demonstrate the wetting behavior control of polymer surfaces doped with photochromic molecules by modifying the surface
patterning features introduced by soft molding lithography. Such surfaces enhance their hydrophilicity upon UV irradiation
due to conversion of the non-polar spiropyran dopant molecules to their polar merocyanine isomers. The process is reversed
upon visible light irradiation. By changing the topological parameters of the introduced pattern, one achieves surface tuning
from hydrophobic to hydrophilic situations. The difference for the contact angles between UV- and green-irradiated surfaces
may become significantly higher than for the flat surfaces, for the specific patterning parameters analyzed.
PACS 42.62.-b; 68.08.Bc; 83.50.Uv; 42.70.Jk; 42.70.Gi 相似文献
4.
Fuhrer R Herrmann IK Athanassiou EK Grass RN Stark WJ 《Langmuir : the ACS journal of surfaces and colloids》2011,27(5):1924-1929
Surface-modified magnetic nanoparticles can be used in extraction processes as they readily disperse in common solvents and combine high saturation magnetization with excellent accessibility. Reversible and recyclable adsorption and desorption through solvent changes and magnetic separation provide technically attractive alternatives to classical solvent extraction. Thin polymer layered carbon-coated cobalt nanoparticles were tagged with β-cyclodextrin. The resulting material reversibly adsorbed organic contaminants in water within minutes. Isolation of the immobilized inclusion complex was easily carried out within seconds by magnetic separation due to the strong magnetization of the nanomagnets (metal core instead of hitherto used iron oxide). The trapped molecules were fully and rapidly recovered by filling the cyclodextrin cavity with a microbiologically well accepted substitute, e.g., benzyl alcohol. Phenolphthalein was used as a model compound for organic contaminants such as polychlorinated dibenzodioxins (PCDDs) or bisphenol A (BPA). Fast regeneration of nanomagnets (compared to similar cyclodextrin-based systems) under mild conditions resulted in 16 repetitive cycles (adsorption/desorption) at full efficiency. The high removal and regeneration efficiency was examined by UV-vis measurements at chemical equilibrium conditions and under rapid cycling (5 min). Experiments at ultralow concentrations (160 ppb) underline the high potential of cyclodextrin modified nanomagnets as a fast, recyclable extraction method for organic contaminants in large water streams or as an enrichment tool for analytics. 相似文献
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Photocontrolled variations in the wetting capability of photochromic polymers enhanced by surface nanostructuring 总被引:2,自引:0,他引:2
Athanassiou A Lygeraki MI Pisignano D Lakiotaki K Varda M Mele E Fotakis C Cingolani R Anastasiadis SH 《Langmuir : the ACS journal of surfaces and colloids》2006,22(5):2329-2333
The wetting characteristics of surfaces of polymers doped with photochromic spiropyran molecules can be tuned when irradiated with laser beams of properly chosen photon energy. The hydrophilicity is enhanced upon UV laser irradiation since the embedded nonpolar spiropyran molecules convert to their polar merocyanine isomers. The process is reversed upon green laser irradiation. Structuring of the photochromic polymeric surfaces with soft lithography enhances significantly the hydrophobicity of the system, indicating that the water droplets on the patterned features interact with air that is trapped in the microcavities, thus creating superhydrophobic air-water contact areas. Furthermore, the light-induced wettability variations of the structured surfaces are enhanced by a factor of 3 compared to those on the flat surfaces. This significant enhancement is attributed to the photoinduced reversible volume changes to the imprinted gratings, which additionally contribute to the wettability changes due to the light-induced photochromic interconversions. 相似文献
7.
Niranjan Patra Marco SalernoM. Malerba P. Davide CozzoliAthanassia Athanassiou 《Polymer Degradation and Stability》2011,96(7):1377-1381
The thermal degradation behaviour of oleic acid-capped colloidal anatase TiO2 nanorods, poly(methyl methacrylate), and their nanocomposites has been studied. Thermogravimetric and differential thermal analysis have been carried out in nitrogen atmosphere for both nanorods, and nanocomposites with nanorod loading from 5 to 30 wt% relative to the polymer. Our study shows that the degradation of the oleic acid-capped nanorods in nitrogen is mainly endothermic and occurs in two steps. The thermal stability of the nanocomposites is improved on increasing the filler loading in the considered range, as the nanorods prevent rapid heat diffusion and limit further degradation. This effect seems to be favoured by the nanorods increased mobility, leading to enhanced dispersion in the matrix upon heating the samples during the thermal analysis. 相似文献
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Assembled metal-insulator nanoparticles with a core-shell geometry provide access to materials containing a large number (>10(6)) of tunneling barriers. We demonstrate the production of ceramic coated metal nanoparticles exhibiting an exceptional pressure-sensitive conductivity. We further show that graphene bi- and trilayers on 20 nm copper nanoparticles are insulating in such a core-shell geometry and show a similar pressure-dependent conductivity. This demonstrates that core-shell metal-insulator assemblies offer a route to alternative sensing materials. 相似文献