A novel concept of advanced SERS (surface enhanced Raman spectroscopy) planar sensors is suggested for fast analysis of sulfur-containing hazardous oil components and persistent pollutants. The main advantage of the proposed sensors is the utilization of an additional preconcentrating layer of optically transparent chitosan gel, which is chemically modified with appropriate π-acceptor compounds to selectively form charge-transfer complexes (CTCs) at the interface with nanostructured silver coatings. The CTCs shift absorption bands of polycyclic aromatic sulfur heterocycles (PASHs) and other important analytes in a controllable way and thus provide a surplus enhancement of vibration modes due to resonant Raman scattering. This novel indicator system provides multiplex determination of PASHs in different forms in a small volume of oil without any tedious sample pretreatment steps. This approach opens new possibilities of increasing either spectral and concentration sensitivity or specificity of SERS-based sensors, allowing for new developments in the fields of ecology, advanced fuel analysis, and other prospective applications.

This communication suggests a new approach expanding the range of important analytes becoming available for Raman scattering enhancement due to entrapping them into charge-transfer complexes immobilized onto nanostructured substrates.

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The paper studies the Krugman's CP model in the weakly explored case of asymmetric regions in two settings: international trade and agglomeration processes. First setting implies that the industrial labor is immobile, while second one consider mobile industrial labor and long-run equilibria. Analytical study of both settings requires application of advanced mathematical analysis, e.g. implicit function theory. For international trade we find how equilibrium prices, production, consumption, wages and welfare for all population groups respond to shifts in all exogenous parameters: characteristics of utility function, transportation costs and degree of asymmetry in initial labor endowment. As for agglomeration process, it was found that the asymmetry in the population distribution simplifies pattern of agglomeration, making the direction of migration more definite, so the well-known ambiguity of final destination may disappear under sufficiently large extent of asymmetry. From political point of view, it means that under some conditions, openness of international trade may be harmful to immobile population of the smaller country.

A new method of microbead silica preparation with polyhedral 20–50 nm silver nanoparticles encrusting silica surface. Such microengineered building blocks are stored safely in a sacrificial biopolymer (ethylcellulose) film.