We introduce a low refractive index layer between the metal and the gain medium in metal-coated laser resonators and demonstrate that it can significantly reduce the dissipation losses. Analysis of a gain medium waveguide shows that for a given waveguide radius, the low index layer has an optimal thickness for which the lasing threshold gain is minimal. The waveguide analysis is used for the de...

One hundred strains of Gram-negative bacteria were isolated from a brackish water Lagoon, Küçükçekmece in Istanbul-Turkey. Identification studies showed that 31% of the isolated bacteria were Escherichia coli, 28% were Citrobacter, and 12% were Enterobacter. Antibiotic and heavy metal resistances exhibited by these bacteria were evaluated. In antibiotic susceptibility tests, 68% of the isolates...

X-ray computed tomography (CT) techniques have been used to evaluate a structural index of high performance metal matrix composites (MMC). Beside of classical features like the determination of number of fibres and eccentricity of fibre bundles an order parameter can be defined and demonstrated for the SiC fibre arrangement in Ti-MMC, which can be used to assess these materials. The samples for...

Negative-index metamaterials (NIMs) at near infrared wavelengths (~2 mum) are fabricated with circular, elliptical and rectangular holes penetrating through metal/dielectric/metal films. All three NIM structures exhibit similar figures of merit; however, the transmission is higher for the NIM with rectangular holes as a result of an improved impedance match with the substrate-superstrate (air-g...

OBJECTIVES The aim of this study was to evaluate the clinical performance of posterior, metal-free polymer crowns with and without a glass-fiber framework, in comparison to metal-ceramic crowns. METHODS After randomisation, 80 single crowns, manufactured from a newly designed polymer composite, were set in posterior teeth. Half of these received a glass-fiber framework, while half were prepar...

The bioavailability of Cd, Cu, Zn, and Pb from two metal-contaminated sediments (Bidassoa and Dunkerque) was studied using Crassostrea gigas larvae exposed to sediment elutriates. The metal contents within the sediments, the larvae and larval growth, the condition index, and the induction of metallothionein in the larvae were measured. The larval growth and condition index were only affected af...

Background & Aims of the Study: Due to the increased human activities around the Agh Gel wetland, this study aimed to measured accumulations of heavy metals (Ni, Pb and Zn) in the surface sediment samples taken from this wetland. Materials & Methods: Samples were taken from 10 stations and exposed to bulk digestion and chemical partitioning. Finally, Ni, Pb and Zn conce...

As a result of the continuous urbanization and industrialization in China over the last few decades, heavy metals have been continuously emitted into urban environments and now pose serious threats to human health. In the present study, an extensive urban near-surface dust survey was conducted in Changchun, China, to evaluate the current status of heavy metal contamination in urban dust and to ...

After the analysis of surface samples and core samples collected in Xinyanggang tidal land, the contents of Pb, Cu, Zn, and Cr were obtained and analyzed in this paper. The heavy metal accumulation rule and pollution status were studied by Index of geo-accumulation, latent ecological risk index method, and elements accumulation index method. The research suggests that (1) the contents of heavy ...

Heavy metal contamination of minesoils is a widespread problem in China. In Pingle manganese mineland in Guangxi (south China), heavy metal concentrations in soils and dominant plants were determined, and soil contamination was assessed with pollution index (Pi) and index of geoaccumulation (I-geo). Pi showed the minesoil was heavily polluted by Cd and slightly polluted by Cr. I-geo showed a se...