Geochemical study of fluids on Lesbos island, Greece

Sixty-five water samples and seven associated gas samples have been collected on Lesbos island. The lithology and structural setting have resulted in two main types of hydrological circulation: a shallow circulation hosting low-salinity cold waters and a deeper one, hosting high-salinity hot waters that often emerge in thermal springs near the coast. The cold waters are characterized by Ca(Mg)-HCO₃(SO₄) composition, while the thermal waters generally have an Na-Cl composition. The chemical features of the former can be explained by their circulation in the ophiolite-bearing phyllitic basement and volcanic rocks. Waters circulating in the ultramafic layers of the basement are richer in Mg than the waters whose circulation is mainly within marble levels or volcanic rocks. The Na-Cl thermal waters are characterized by salinities ranging from 1910 to 35,700 mg/kg. As indicated by previous hydrogeochemical and isotopic studies, the Na-Cl composition of the thermal waters on Lesbos is the result of mixing between shallow meteoric waters and marine waters. While interacting with the minerals of the geothermal reservoir, the saline waters retain the Na/Cl sea water ratio but become enriched in Ca²⁺ and depleted in Mg²⁺ with respect to sea water.Processes of hydrothermal alteration at depth are activated by a gas phase enriched in CO₂, which reaches the geothermal reservoir by rising along the deep fractures of the basement. Thermodynamic calculations based on hydrothermal alteration processes occurring at the estimated temperatures of the geothermal reservoir (about 120 °C) indicate that the thermal waters of Lesbos are in equilibrium with talc and dolomite.     

Vortex Structures in a Chain of Coupled Bosonic Wells and the Mott Regime

We describe a system of coupled bosonic wells by means of the Bose-Hubbard model. Its dynamics is investigated via the time-dependent variational principle and coherent states. Some exact solutions of the dynamics, which have a vortex-like structure, are explicitly found, and used together with semiclassical requantization to describe the dynamics in the Mott insulator regime.     

Learning natural scene categories by selective multi-scale feature extraction

Natural scene categorization from images represents a very useful task for automatic image analysis systems. In the literature, several methods have been proposed facing this issue with excellent results. Typically, features of several types are clustered so as to generate a vocabulary able to describe in a multi-faceted way the considered image collection. This vocabulary is formed by a discrete set of visual codewords whose co-occurrence and/or composition allows to classify the scene category. A common drawback of these methods is that features are usually extracted from the whole image, actually disregarding whether they derive properly from the natural scene to be classified or from foreground objects, possibly present in it, which are not peculiar for the scene. As quoted by perceptual studies, objects present in an image are not useful to natural scene categorization, indeed bringing an important source of clutter, in dependence of their size.     

Use of compatible blends to fabricate carbon black composite vapor detectors

The aim of this work was the development of materials to be used in the field of gas sensing for the detection of organic vapors. Conductive sensors were prepared with carbon black filled blends of poly(vinyl chloride) and diol‐terminated poly(?‐caprolactone), an oligomeric plasticizer. For comparison, blends with di(2‐ethylhexyl)phthalate, a traditional low‐molecular‐weight plasticizer, were also prepared. All sensors were tested upon exposure to different organic vapors. In general, the plasticizer content affected the response rates of the sensors, and a linear variation of the relative resistance with the analyte concentration was observed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1816–1821, 2004     

Determination of PCBs in fatty tissues by means of several detection techniques

Difficulties with harmonization of analytical procedures and consequently poor comparability of generated data represent in the Czech Republic the main reason for the delay in issuing of updated legislation for polychlorobiphenyls (PCBs) in foodstuffs. This study draws attention to possible errors (overestimations) that can occur during routine determination of these residues in the fat portion of biotic matrices. We demonstrate the gas Chromatographic (GC) conditions under which interfering contaminants such as phthalates and/or chlorinated pesticides can be separated from analytes. Discussion is focused on the advantages and drawbacks of GC with an electron capture detector, GC mass spectrometry and GC with an atomic emission detector. Various approaches used for calculation of PCBs contents are compared.

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Bestimmung der PCB in Fettgeweben mittels verschiedener Detektionstechniken

Zusammenfassung Das Problem mit der Harmonisierung der analytischen Verfahren und der geringen Vergleichbarkeit der Angaben ist ein Hauptgrund der Verspätung in der neuen Legislative für PCB in Lebensmitteln in der Tschechischen Republik. Die Arbeit beschreibt die möglichen Fehler (Falsch-positive Fehler), die durch die routinierte Bestimmung von PCB-Rückständen in Fettanteilen der biologischen Materialien auftreten können. Es werden die gaschromatographischen Bedingungen beschrieben, unter denen die Interferenzen, wie z. B. Phthalaten und chlorierten Pesticiden, von Stoffen abgetrennt werden können. Die Vorteile und Nachteile der Methoden GC-ECD, GC-MS und GC-AED werden diskutiert. Die verschiedenen für die Kalkulation des PCB-Gehaltes angewendeten Annäherungen werden miteinander verglichen.

     

Photodegradable polyethylene

Polymer photodegradation can be achieved by introducing carbonyl groups which absorb radiations above the 300 mμ wavelength and thus are sensitized by solar or atmospheric radiations. We introduced these groups in polyethylene by oximation of aliphatic chain with photoactivated NOCI and hydrolysis of the oxime. Modified polymers show, during accelerated aging in Weather-O-Meter, a constant molecular weight decrease, which is directly proportional to the concentration of carbonyl groups.     

Curcumin and the cellular stress response in free radical-related diseases

Free radicals play a main pathogenic role in several human diseases such as neurodegenerative disorders, diabetes, and cancer. Although there has been progress in treatment of these diseases, the development of important side effects may complicate the therapeutic course. Curcumin, a well known spice commonly used in India to make foods colored and flavored, is also used in traditional medicine to treat mild or moderate human diseases. In the recent years, a growing body of literature has unraveled the antioxidant, anticarcinogenic, and antinfectious activity of curcumin based on the ability of this compound to regulate a number of cellular signal transduction pathways. These promising data obtained in vitro are now being translated to the clinic and more than ten clinical trials are currently ongoing worldwide. This review outlines the biological activities of curcumin and discusses its potential use in the prevention and treatment of human diseases.