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    Wyświetlanie 1-11 z 11
    Tytuł:
    Positron study of the structure of nonadecane-tricosane mixed solid
    Autorzy:
    Zgardzińska, B.
    Goworek, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/146297.pdf
    Data publikacji:
    2010
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    positron annihilation
    n-alkanes
    binary mixture
    Opis:
    Positron annihilation lifetime and intensity were measured as a function of temperature for a binary mixture of two normal alkanes. The rotator phase is preceded by the range of about 7 K, in which one observes instability of spectrum parameters. In that range the mixed solid, being initially introduced into rotator phase, transforms to a rigid one in the time scale of several hours.
    Źródło:
    Nukleonika; 2010, 55, 1; 47-49
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Distribution and sources of n-alkanes in surface sediments of Taihu Lake, China
    Autorzy:
    Yu, Y.
    Li, Y.
    Guo, Z.
    Zou, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/205298.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    n-alkanes
    surface sediments
    Taihu Lake
    Opis:
    The last study on n-alkanes in surface sediments of Taihu Lake was in 2000, only 13 surface sediment samples were analysed, in order to have a comprehensive and up-to-date understanding of n-alkanes in the surface sediments of Taihu Lake, 41 surface sediment samples were analyzed by GC-MS. C10 to C37 were detected, the total concentrations of n-alkanes ranged from 2109 ng g−1 to 9096 ng gg−1 (dry weight). There was strong odd carbon predominance in long chain n-alkanes and even carbon predominance in short chain n-alkanes. When this finding was combined with the analysis results of wax n-alkanes (WaxCn), carbon preference index (CPI), unresolved complex mixture (UCM), hopanes and steranes, it was considered that the long chain n-alkanes were mainly from terrigenous higher plants, and that the short chain n-alkanes mainly originated from bacteria and algae in the lake, compared with previous studies, there were no obvious anthropogenic petrogenic inputs. Terrestrial and aquatic hydrocarbons ratio (TAR) and C21−/C25+ indicated that terrigenous input was higher than aquatic sources and the nearshore n-alkanes were mainly from land-derived sources. Moreover, the distribution of short chain n-alkanes presented a relatively uniform pattern, while the long chain n-alkanes presented a trend that concentrations dropped from nearshore places to the middle of lake.
    Źródło:
    Archives of Environmental Protection; 2016, 42, 1; 49-55
    2083-4772
    2083-4810
    Pojawia się w:
    Archives of Environmental Protection
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    An Improved Approximation for DIPPR-Based Predicting Speed of Sound in Long-Chained n-Alkanes
    Autorzy:
    Postnikov, E. B.
    Nedyalkov, Y. V.
    Polishuk, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/177788.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    n-alkanes
    isothermal compressibility
    speed of sound
    Opis:
    In this short communication, we revise a correlation for the saturated liquid isothermal compressibility based on the data available in DIPPR (Postnikov, 2016) which considers the molecular non-sphericity and addresses a problem of predicting speeds of sound in saturated long-chained alkanes. In addition, we correct a misprint appeared in the cited work and provide programming code used for the realisation of the proposed calculations.
    Źródło:
    Archives of Acoustics; 2018, 43, 3; 537-541
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Estimation of pasture herbage intake by beef cattle based on n-alkanes as markers
    Ocena spożycia runi łąkowej przez bydło mięsne w oparciu o zawartość wskaźnikowych n-alkanów
    Autorzy:
    Nowakowski, Piotr
    Czyz, Katarzyna
    Iwaszkiewicz, Marta
    Powiązania:
    https://bibliotekanauki.pl/articles/1631358.pdf
    Data publikacji:
    2017
    Wydawca:
    Polskie Towarzystwo Botaniczne
    Tematy:
    cattle
    grass intake
    dry matter
    n-alkanes
    Opis:
    The aim of the study was to evaluate herbage dry matter intake in 16 beef cows which grazed continuously on permanent pastures within the “The Warta Estuary” National Park (Poland), using the minimally invasive method based on n-alkanes as markers (C29, C31, C33). Significant differences were observed in the nutritive value of herbage collected for analyses by cutting or nipping. The calculated content of energy and protein in the nipped herbage was higher: UFL by 58.1% and PDI by 50%, with a higher digestibility of nutrients. The values obtained for DM intake in pasture herbage by cows were closest to the standards when calculations were based on the C29/C32 pair of n-alkanes. However, the best prediction of DM intake estimation from creeping bentgrass (Agrostis stolonifera) pasture, in agreement with the accepted energy and protein standards, was based on the proportions between alkanes C31/C32.
    Celem badań była ocena spożycia suchej masy roślinnej na przykładzie 16 krów mięsnych, które w sposób ciągły wypasane były na pastwiskach w Parku Narodowym „Ujście Warty” (Polska), z zastosowaniem minimalnie inwazyjnej metody wykorzystującej jako wskaźniki n-alkany (C29, C31, C33). Istotne różnice zaobserwowano w przypadku wartości odżywczej roślinności pozyskanej do analizy przez koszenie lub uszczykiwanie. Obliczona zawartość energii i białka była wyższa w przypadku roślin uszczykiwanych: UFL o 58.1%, a PDI o 50%, czemu towarzyszyła wyższa strawność składników odżywczych. Wartości dotyczące pobrania suchej masy wraz z roślinnością przez zwierzęta były najbliższe norm, gdy obliczenia oparto na stosunku n-alkanów C29/C32. Najdokładniejsze oszacowanie pobrania suchej masy z mietlicy rozłogowej (Agrostis stolonifera) z pastwiska, zgodne z przyjętymi normami dotyczącymi energii i białka, uzyskano w oparciu o stosunek alkanów C31/C32.
    Źródło:
    Acta Agrobotanica; 2017, 70, 1
    0065-0951
    2300-357X
    Pojawia się w:
    Acta Agrobotanica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Preliminary suggestions on the Pleistocene palaeovegetation around the Biśnik Cave (Częstochowa Upland, Poland) based on studies of molecular fossils from cave sediments
    Autorzy:
    Krajcarz, Maciej T.
    Gola, Marek R.
    Cyrek, Krzysztof J.
    Powiązania:
    https://bibliotekanauki.pl/articles/2026713.pdf
    Data publikacji:
    2010
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    cave sediments
    biomarkers
    n-alkanes
    gas chromatography
    palaeoenvironment
    Opis:
    Bioenik Cave is an im por tant site of Mid dle Palaeo lithic, with the lon gest se quence of Neanderthal set tle ment phases in Cen tral Eu rope. In the pre vi ous stud ies of the Bioenik sed i ments, dif fer ent el e ments of palaeoenvironment in the pe ri - ods of Neanderthal oc cu pa tion have been re cog nised, ex cept of palaeovegetation, which could not be de rived be cause of lack of pre served plant mi cro- or macrofossils. The cur rent work is an at tempt to re con struct palaeovegetation in vi - cin ity of the Bioenik Cave, us ing anal y sis of com po si tion of plant-de rived n-al kanes, pre served in sed i ments. In our study, we an a lyzed one sam ple from each of the sed i ment’s lay ers 11 – 19c (early Late Pleis to cene and late Mid dle Pleis to cene). Abun dant n-al kanes (mostly n-C27, n-C29 and n-C31) were found in all the sam pled lay ers ex cept for the lay ers 12, 16 and 19d, show ing no al kanes at all. There is clear di ver si fi ca tion of n-al kanes com po si tion and CPI (car bon pref er ence in dex) val ues be tween lay ers. Anal y sis of this com po si tion, al lows us to claim that the lay ers 11 and 14 were ac cu mu lated when the cave’s vi cin ity was cov ered by dense co nif er ous for ests, hence upon warm cli mate. The lay ers 19, 19a lower, 19b and 19c, pre sumably orig i nated dur ing cold pe ri ods when open wood lands or grass lands dom i nated. The other an a lyzed lay ers could be con nected with in ter me di ate veg e ta tion in form of open wood land. How ever, not all of the achieved re sults stay in com pli ance with the ac tual stra tig ra phy, es tab lished bas ing on lithological data and palaeo ec ol ogy of fos sil fauna, and we hope that ex pla na tion of this dis crep ancy would be pos si ble af ter more ex ten sive stud ies of mo lec u lar fos sils are done.
    Źródło:
    Studia Quaternaria; 2010, 27; 55-61
    1641-5558
    2300-0384
    Pojawia się w:
    Studia Quaternaria
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Ortho-para spin conversion of Ps by paramagnetic O2 dissolved in organic compounds
    Autorzy:
    Zgardzińska, B.
    Białko, W.
    Jasińska, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/971542.pdf
    Data publikacji:
    2015
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    alcohols
    cyclohexane
    isooctane
    n-alkanes
    ortho-para conversion
    paramagnetic molecule
    Opis:
    The o-Ps mean lifetime value in liquids decreases in the presence of the paramagnetic oxygen molecules via the ortho-para conversion process. This effect was observed for several organic samples composed of carbon and hydrogen atoms differing in the arrangement of atoms forming the molecule, e.g. n-alkanes, alcohols, branched isomer of alkane, cycloalkane. The usually observed tendency of the o-Ps lifetime value to be an increasing function of temperature (in the case of measurements performed in vacuum) changes to a decreasing one in the presence of O2 dissolved in the sample. The difference between the o-Ps lifetimes measured in samples in vacuum and in the presence of O2 increases with the distance from the melting point. The ortho-para constant rate λconv was estimated to be ~130 μs–1 at 300 K for three compounds investigated.
    Źródło:
    Nukleonika; 2015, 60, No. 4, part 1; 801-804
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Geochemical characterization and palaeoenvironmental implications of lipids in Neogene lignites and lignitic shales in NW Poland
    Autorzy:
    Czechowski, Franciszek
    Polowczyk, Marzena
    Simoneit, Bernt R. T.
    Grelowski, Cezary
    Hojniak, Marek
    Powiązania:
    https://bibliotekanauki.pl/articles/27311291.pdf
    Data publikacji:
    2023
    Wydawca:
    Polskie Towarzystwo Geologiczne
    Tematy:
    Lignites
    biomarkers
    n-alkanes and isoprenoids
    diterpenoids
    triterpenoids
    polycyclic aromatic hydrocarbons
    Opis:
    The lipophilic biomarker distributions in lipids of Neogene lignites and lignitic shales in western Pomerania and the midlands of Poland are presented. Twenty-six lignite samples and seven lignitic shales were obtained from twenty-four boreholes. Their extracts were separated, using thin-layer chromatography, and the saturate and aromatic fractions were analyzed by gas chromatography-mass spectrometry. The molecular compositions of n-alkanes, isoprenoids, n-alkylcyclohexanes, n-alkylbenzenes, tri- and tetracyclic diterpenoids, pentacyclic triterpenoids, as well as polycyclic aromatic hydrocarbons (PAHs) with up to five rings, were determined. The samples displayed n-alkane distributions in the range of C14–C35 and high odd-over-even carbon number predominances (CPI(25–33) from 2.9 to 7.9). Diterpanes consisted primarily of phyllocladane, abietane, isopimarane, labdane, and kaurane structures, although their abundances varied among the samples. Hopanes exhibited the biological and geochemical characteristics of low-maturity organic matter. Minor oleanane triterpenoids from angiosperms were also found. A few samples displayed evidence of biodegradation on the basis of the advanced isomerization of αβ-hopanes and the presence of short-chained n-alkanes, n-alkylcyclohexanes, and n-alkylbenzenes. A more mature stage of the above biomarkers also may have resulted in part from the oxidation of organic matter. The lignite source materials were derived from conifer and angiosperm flora as well as microbial remnants. The contribution from marine phytoplankton was excluded on the basis of the lack of C27 steroids. PAHs were predominantly perylene or phenanthrene, with minor other analogues. Thus, the data support progressive lacustrine/lagoonal sedimentation in the palaeoenvironmental mires.
    Źródło:
    Annales Societatis Geologorum Poloniae; 2023, 93, 4; 447--466
    0208-9068
    Pojawia się w:
    Annales Societatis Geologorum Poloniae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Łupki antrakozjowe niecki śródsudeckiej w świetle wskaźników geochemii organicznej - wstępne wyniki analizy bituminów
    The Anthracosia Shales from the Intra-Sudetic Basin in the light of organic geochemistry proxies - preliminary results of bitumen study
    Autorzy:
    Dąbek-Głowacka, Jolanta
    Wójcik-Tabol, Patrycja
    Nowak, Grzegorz J.
    Wendorff-Belon, Małgorzata
    Marynowski, Leszek
    Powiązania:
    https://bibliotekanauki.pl/articles/20248857.pdf
    Data publikacji:
    2023
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    antrakozjowe niecki
    n-alkany
    dojrzałość materii organicznej
    Anthracosia Shales
    n-alkanes
    organic matter maturity
    Opis:
    The lacustrine Anthracosia Shales of the Intra-Sudetic Basin are sediments that have become the subject of interest due to their dark colour, indicating an increased content of dispersed organic matter. The published data concern the characteristics of macerals, vitrinite reflectance, the results of Rock-Eval pyrolysis and the results of palynological tests. The above studies were supplemented with the current analysis of the extracted bitumens. The results of the distribution of n-alkanes in the Anthracosia Shales corresponds with the results of macerals and palynology. The dominance of short-chain homologues indicates the microbial-algal origin of the organic matter. Some contribution of terrestrial organic matter is not excluded. Three lithofacies intervals differing geochemically have been distinguished: I - dark grey calcareous claystones rich in aliphatic compounds of microbial and algal origin; II - grey mudstones with siderites containing a lower amount of aliphatic compounds in favour of polar and aromatic compounds; III -weakly calcareous mudstones and sandstones, poor in terrestrial organic matter. The distribution of n-alkanes, phenanthrene and methylphenanthrenes (CPI, MPI, MPR, PP1) shown that the maturity of the organic substance is within the oil window. This is further supported by the Rock-Eval data and vitrinite reflectance values.
    Źródło:
    Przegląd Geologiczny; 2023, 71, 5; 269-273
    0033-2151
    Pojawia się w:
    Przegląd Geologiczny
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Mixtures of selected n-alkanes and Au nanoparticels for optical fiber threshold temperature transducers
    Autorzy:
    Przybysz, N.
    Marć, P.
    Tomaszewska, E.
    Grobelny, J.
    Jaroszewicz, L. R.
    Powiązania:
    https://bibliotekanauki.pl/articles/1818233.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
    Tematy:
    optical fiber sensors
    temperature treshold sensors
    gold nanoparticles
    n-alkanes
    photonic crystal transducers
    Opis:
    Thermo-optic properties enhancement of the bi-stable temperature threshold sensors based on a partially filled photonic crystal fiber was reported. Previously tested transducers filled with a selected group of pure n-alkanes had in most cases differences between switching ON and OFF states. Therefore, the modification of filling material by using additional crystallization centers in the form of gold nanoparticles was applied to minimize this undesirable effect. The evaluation of the thermodynamic properties of pentadecane and its mixtures with 14 nm spherical Au nanoparticles based on the differential scanning calorimetry measurements was presented. Optical properties analysis of sensors prepared with these mixtures has shown that they are bounded with refractive index changes of the filling material. Particular sensor switches ON before melting process begins and switches OFF before crystallization starts. Admixing next group of n-alkanes with these nanoparticles allows to design six sensors transducers which change ON and OFF states at the same temperature. Thus, the transducers with a wider temperature range for fiber-optic multi-threshold temperature sensor tests will be used.
    Źródło:
    Opto-Electronics Review; 2020, 28, 4; 220--228
    1230-3402
    Pojawia się w:
    Opto-Electronics Review
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Mixtures of selected n-alkanes and Au nanoparticels for optical fiber threshold temperature transducers
    Autorzy:
    Przybysz, N.
    Marć, Paweł
    Tomaszewska, E.
    Grobelny, Jarosław
    Jaroszewicz, Leszek R.
    Powiązania:
    https://bibliotekanauki.pl/articles/1818228.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
    Tematy:
    optical fiber sensors
    temperature treshold sensors
    gold nanoparticles
    n-alkanes
    photonic crystal transducers
    Opis:
    Thermo-optic properties enhancement of the bi-stable temperature threshold sensors based on a partially filled photonic crystal fiber was reported. Previously tested transducers filled with a selected group of pure n-alkanes had in most cases differences between switching ON and OFF states. Therefore, the modification of filling material by using additional crystallization centers in the form of gold nanoparticles was applied to minimize this undesirable effect. The evaluation of the thermodynamic properties of pentadecane and its mixtures with 14 nm spherical Au nanoparticles based on the differential scanning calorimetry measurements was presented. Optical properties analysis of sensors prepared with these mixtures has shown that they are bounded with refractive index changes of the filling material. Particular sensor switches ON before melting process begins and switches OFF before crystallization starts. Admixing next group of n-alkanes with these nanoparticles allows to design six sensors transducers which change ON and OFF states at the same temperature. Thus, the transducers with a wider temperature range for fiber-optic multi-threshold temperature sensor tests will be used.
    Źródło:
    Opto-Electronics Review; 2020, 28, 4; 220--228
    1230-3402
    Pojawia się w:
    Opto-Electronics Review
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Organic geochemistry of the Grodziec beds (Upper Carboniferous) : Upper Silesian Coal Basin, Poland
    Autorzy:
    Bzowska, G.
    Fabiańska, M.
    Matuszewska, A.
    Racka, M.
    Skręt, U.
    Powiązania:
    https://bibliotekanauki.pl/articles/2059437.pdf
    Data publikacji:
    2000
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    Upper Silesia
    Carboniferous
    sedimentary organic matter
    capillary gas chromatography
    infrared spectrometry
    X-ray differention
    n-alkanes
    hopanes
    Opis:
    Five lithologically different rock samples from the "Niwka" brickyard exposure, including one coal sample, were geochemically characterized as regards their mineral composition and sedimentary organic matter present in them. Various methods, including: X-ray diffraction, solvent extraction, group separation by preparative thin layer chromatography, infra-red spectroscopy for assessment of the content of different functional groups in total rock extracts and their separated polar compound fractions, and capillary gas chromatography for analysis of aliphatic hydrocarbon fractions. It was found that the "Niwka" brickyard rocks are rich in organic material present as the plant detritus (cane-break) or as compounds adsorbed on clay and carbonaceous minerals. Yields of bitumen extraction, group composition of extracts and content of various functional groups assessed by infra-red spectra seem to be related to mineral composition of the host rocks and type of kerogen present. Higher contents of clay minerals, especially chlorite, enriches both extracts and their polar compound fractions in aliphatic structures while the organic matter of both sandstones analysed contains more condensed aromatic structures and functional oxygen groups. Generally the organic matter of the host rocks was deposited in an oxic environment and belongs to type III kerogen with a dominant terrestrial biogenic source or to type II kerogen of bacterial/terrestrial origin of primary biogenic matter. Its thermal maturity stage can be estimated as end-diagenetic or early catagenetic. The highest maturity is shown by the organic matter in the basal sandstone (the S2 sandstone) and probably is caused by imput of older migrating bitumen. Biodegradation of organic matter seems to be influenced by the mineral composition of the host rock, with a high content of clay minerals giving protection.
    Źródło:
    Geological Quarterly; 2000, 44, 4; 425-437
    1641-7291
    Pojawia się w:
    Geological Quarterly
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-11 z 11

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