56 research outputs found

    Vibron transport in macromolecular chains

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    We study the hopping mechanism of the vibron excitation transport in the simple 1D model of biological macromolecular chains. We supposed that the vibron interaction with thermal oscillations of the macromolecular structural elements will result in vibron self -trapping, and the formation of the partial dressed vibron state. With use of the modified Holstein polaron model, we calculate vibron diffusivity in dependence of the basic system parameters and temperature. We obtain that the vibron diffusivity smoothly decreases in non adiabatic limit when the strength of the vibron-phonon coupling grows. However this dependence becomes by discontinuous one in case of growth of the adiabaticity of the system. The value of the critical point depends of the system temperature, and at room temperatures it belongs to the low or intermediate coupling regime. We discuss an application of these results to study of vibron transport to 3D bundles of such macromolecules chains considering it as polymer nanorods and to 2D polymer films organized from such macromolecules.Comment: 4 pages, 6 figures, contribution to the Proceedings of the Conference "Physical mesomechanics of multi-level systems`2014", September 3-5 2014, Tomsk, Russi

    Geochemical Baseline Mapping of Soils Developed on Diverse Bedrock from Two Regions in Croatia

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    The comparison of contents and distribution maps for Al, As, Ba, Ca, Co, Cr, Cu, Fe, La, K, Na, Ni, Mg, Mn, P, Pb, Sc, Sr, Ti, Th, V, Y, Zn and Hg in the topsoil cover of two typical regions are given. One is a carbonate bedrock (karst) dominated region (southern Dalmatia) and the other a non-carbonate bedrock dominated region (NW Croatia). The results imply that the soils developed on carbonate bedrock have higher mean values of almost all elements excluding K, Na, Mg and Ba, which are lower in carbonate terrains. In comparison with the non-carbonate terrains, for the carbonate terrains the following elements have higher mean concentrations: Al, As, Co, Cu, Fe, La, Mn, Pb, Ni, Mn, Th, V, Cr, Zn, Zr and Nb, while Sr, P and Ti have similar contents. Approximately 4% of the sites can be considered as moderately enriched (polluted) in Pb, either from mining activities or airborne deposition. Only a limited number of sampling sites can be directly linked with mineralization. The derived factors are usually interpreted as associations of elements that imply a common source or behavior in regard to geogenic or anthropogenic influences. It was found that difference between the northwestern Croatia and southern Dalmatia is not expressed only by concentration differences but also by element associations. Five factor models accounting most of the data variability seemed appropriate to portray the geochemical variability within the topsoil of both region

    Application of a New Potentiometric Sensor for Determination of Anionic Surfactants in Wastewater

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    A new screen-printed potentiometric microsensor (SPMS) for the determination of anionic surfactants (ASs) based on the dimethyldioctadecylammonium-tetraphenylborate (DDA-TPB) ion pair as a sensing material was applied to real industrial effluents. The sensor is accurate, inexpensive, simple and very sensitive. The solutions of cetylpyridinium chloride (CPC) of the concentrations down to 5Ā· 10ā€“5 mol dmā€“3 were used as a titrant. Standard addition method was used for checking the precision and accuracy of measurements providing satisfactory results with recoveries between 98.3 to 102.0 % in pure AS solutions and 99.0 to 114.5 % in wastewater. Standard spectrophotometric method Methylene Blue Active Substances (MBAS) was used as control for comparison of the results obtained with the new sensor. The results obtained using SPMS were compared with those obtained by the polymeric membrane ion-selective electrodes (ISEs), containing the same sensing material, and exhibited good mutual agreement

    A Factor Model of the Relationship between Stream Sediment Geochemistry and Adjacent Drainage Basin Lithology, Medvednica Mt., Croatia

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    A mathematical model is constructed to relate the geochemical composition of recent stream material in a number of catchments on Medvednica Mt. to a broadely defined bedrock lithology which represents the parent material for the former. It is a system based factor model, which synthesizes eight lithological and 25 geochemical variables (major, minor and trace elements), reducing their relationships to six geologically meaningful factors. Five of these divulged a definite relationship between geochemistry and lithology. These are labelled as follows: factor of metamorphic rocks; factor of igneous rocks; factor of Tertiary carbonate rocks; factor of parametamorphic rocks and factor of Mesozoic carbonate rocks. Two lithologies; the Mesozoic clastic rocks and Quaternary sediments showed no clear association to any of the factors. Alternatively, one of the factors (F2) can be identified as ā€œnon-lithologicā€ indicating other, perhaps anthropogenic, contributions to the stream sediment geochemical composition

    Influence of the electron-phonon iinteraction on phonon heat conduction in a molecular nanowire

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    A model for phonon heat conduction in a molecular nanowire is developed. The calculation takes into account modification of the acoustic phonon dispersion relation due to the electron-phonon interaction. The results obtained are compared with models based upon a simpler, Callaway formula

    A 180 ka record of environmental change at Erdut (Croatia): a new chronology for the loessā€“palaeosol sequence and its implications for environmental interpretation

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    While there are numerous thick loessā€“palaeosol sequences preserved across the Carpathian Basin, well dated sites that provide terrestrial palaeoenvironmental records extending beyond last glacialā€“interglacial cycle are scarce. Robust chronologies are essential for correlations of loess with other longā€term Quaternary records and to further understanding of the palaeoenvironment and climate of this important region beyond the last 125 ka. Here a new geochronology based on 13 postā€infrared infrared stimulated luminescence ages focused on the lower part of the loessā€“palaeosol sequence at Erdut is presented. The results show that the lower part of the Erdut profile spans the penultimate glacial cycle (MIS 7 to MIS 5). The considerable sediments overlaying the investigated part of the profile suggest that this section spans two glacial cycles, rather than the previously suggested one. The most likely source of the discrepancy is the use of uncorrected infrared stimulated luminescence signal, which can cause age underestimation if not accounted for. This study demonstrates the need to revisit sites such as Erdut, reā€date them using updated measurement protocols, and update existing palaeoenvironmental interpretations

    Photoacoustic frequency and spectroscopy technique for evaluation opto-thermal properties of macromolecular nanostructures

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    of great importance both from fundamental and applied points of view because these materials are promising in the field of nanowire materials in nano-optics and nanoelectronics. Theoretical investigations, which have recently done for macromolecular nanostructures, indicate different absorption properties as well as heat transport mechanisms for infra-red and visible incident beams. In order to enable experimental proving of theoretical models, we have suggested modification of optical pump part in classical photoacoustic frequency techniques and calculated matched electronic part. We have presented the technique for measurement optical coefficient of absorption and thermal diffusivity of macromolecular nanostructures at large range of infra-red and visible wavelength of pump beams.V International School and Conference on Photonics and COST actions: MP1204, BM1205 and MP1205 and the Second international workshop "Control of light and matter waves propagation and localization in photonic lattices" : PHOTONICA2015 : book of abstracts; August 24-28, 2015; Belgrad

    Charge transport in the alpha-helix proteins

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    In this paper we investigate charge transport in the alpha-helix proteins. It is considered that charge carriers are partially dressed small polarons, that are formed by electron self-trapping in the weak coupling limit. Polaron properties are considered by applying mean-field theory based upon the modified Lang-Firsov transformation and the Bogolyubov theorem. The transport properties have been calculated on the basis of the Holstein MC model. The obtained results are compared with the results of previous models.International Conference on Theoretical Physics Dubna-Nano 2010, Jul 05-10, 2010, Dubna, Russi
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