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Wyszukujesz frazę "Cryogenic" wg kryterium: Wszystkie pola


Wyświetlanie 1-3 z 3
Tytuł:
The cryogenic enrichment system in chromatographic analysis of noble gases in groundwater
Autorzy:
Najman, J.
Śliwka, I.
Powiązania:
https://bibliotekanauki.pl/articles/1075569.pdf
Data publikacji:
2016-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.43.-h
07.20.Mc
92.40.Kf
92.40.-t
Opis:
The concentration of helium in groundwater may be a good environmental tracer for groundwater dating in hydrogeology. In this work, we present a chromatographic method for simultaneous analysis of helium, neon, and argon in groundwater from a single groundwater sample. Proper use of environmental tracers for dating purposes requires the knowledge of the recharge temperature of the system and the excess air. Both parameters can be determined by measuring the concentration of argon and neon in groundwater. The lowest helium concentration in groundwater is 4.8×10¯⁸ cm³_{STP}/g_{H₂O} at sea level and temperature 10°C. In view of the deficiency of a suitable detector with a limit of detection for helium at the level of 4.8×10¯⁸ cm³_{STP}/g_{H₂O}, the application of the enrichment method is necessary. In this work, the cryogenic method of enrichment with activated charcoal at abated pressure conditions was applied. Helium, neon and argon are analyzed on two gas chromatographs equipped with capillary and packed columns (filled with molecular sieve 5A and activated charcoal) and three thermo-conductive detectors. The chromatographic method was applied to groundwater dating from Kraków and Żarnowiec aquifers. The levels of detection for measurement systems for the tested compounds are: 1.9×10¯⁸ cm³_{STP}/cm³ for neon, 3.1×10¯⁶ cm³_{STP}/cm³ for argon, and 1.2×10¯⁸ cm³_{STP}/cm³ for helium.
Źródło:
Acta Physica Polonica A; 2016, 130, 3; 737-742
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Phase Transition in Layered Materials 1T-TaS$\text{}_{x}$Se$\text{}_{2-x}$ Probed by Cryogenic STM/STS
Autorzy:
Hasegawa, T.
Shiino, O.
Yamaguchi, W.
Endo, T.
Sugawara, H.
Kitazawa, K.
Powiązania:
https://bibliotekanauki.pl/articles/1968713.pdf
Data publikacji:
1998-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.30.+h
71.20.-b
Opis:
A metal-insulator transition, Mott transition, in layered materials 1T-TaS$\text{}_{x}$Se$\text{}_{2-x}$ was investigated by cryogenic scanning tunneling microscopy/ spectroscopy. At 77 K, tunneling spectra in the insulating phase showed a conduction band with almost half filling, which becomes narrower as x decreases. Around the transition point x≈1.4 at 77 K, we observed a sign of gap opening without an overshooting peak at zero bias, supporting the Mott localization picture in which a carrier number vanishes at the transition point. From the site-specified scanning tunneling spectroscopy measurements, furthermore, electrons were found to localize at the charge density wave crest positions. In 1T-TaS$\text{}_{2}$, we have also found that both metallic and insulating phases coexist in a nanometer scale just above the transition temperature, 180 K. >From the minimum size of the insulating region, the coherence length of Mott insulating state was evaluated to be≈5 nm.
Źródło:
Acta Physica Polonica A; 1998, 93, 2; 297-305
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nanostructural Superconducting Materials for Fault Current Limiters and Cryogenic Electrical Machines
Autorzy:
Prikhna, T.
Gawalek, W.
Savchuk, Ya.
Sergienko, N.
Moshchil, V.
Sokolovsky, V.
Vajda, J.
Tkach, V.
Karau, F.
Weber, H.
Eisterer, M.
Joulain, A.
Rabier, J.
Chaud, X.
Wendt, M.
Dellith, J.
Danilenko, N.
Habisreuther, T.
Dub, S.
Meerovich, V.
Litzkendorf, D.
Nagorny, P.
Kovalev, L.
Schmidt, Ch.
Melnikov, V.
Shapovalov, A.
Kozyrev, A.
Sverdun, V.
Kosa, J.
Vlasenko, A.
Powiązania:
https://bibliotekanauki.pl/articles/1549637.pdf
Data publikacji:
2010-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Sv
74.81.Bd
74.70.Ad
74.78.Na
74.62.Fj
74.25.Ld
74.62.Dh
74.25.Ha
Opis:
Materials of the Y-Ba-Cu-O (melt-textured $YBa_{2}Cu_{3}O_{7-δ}$-based materials or MT-YBCO) and Mg-B-O ($MgB_{2}$-based materials) systems with high superconducting performance, which can be attained due to the formation of regularly distributed nanostructural defects and inhomogeneities in their structure can be effectively used in cryogenic technique, in particular in fault current limiters and electrical machines (electromotors, generators, pumps for liquid gases, etc.). The developed processes of high-temperature (900-800°C) oxygenation under elevated pressure (16 MPa) of MT-YBCO and high-pressure (2 GPa) synthesis of $MgB_{2}$-based materials allowed us to attain high superconductive (critical current densities, upper critical fields, fields of irreversibility, trapped magnetic fields) and mechanical (hardness, fracture toughness, Young modulus) characteristics. It has been shown that the effect of materials properties improvement in the case of MT-YBCO was attained due to the formation of high twin density (20-22 $μm^{-1}$), prevention of macrocracking and reduction (by a factor of 4.5) of microcrack density, and in the case of $MgB_{2}$-based materials due to the formation of oxygen-enriched as compared to the matrix phase fine-dispersed Mg-B-O inhomogeneities as well as inclusions of higher borides with near-$MgB_{12}$ stoichiometry in the Mg-B-O matrix (with 15-37 nm average grain sizes). The possibility is shown to obtain the rather high $T_{c}$ (37 K) and critical current densities in materials with $MgB_{12}$ matrix (with 95% of shielding fraction as calculated from the resistant curve).
Źródło:
Acta Physica Polonica A; 2010, 117, 1; 7-14
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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