On the electron temperature determination in high-metallicity H ii regions     

Leonid S. Pilyugin 《Monthly notices of the Royal Astronomical Society》2007,375(2):685-690

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Surface abundances of light elements for a large sample of early B-type stars – II. Basic parameters of 107 stars     

Leonid S. Lyubimkov  Tamara M. Rachkovskaya  Sergey I. Rostopchin  David L. Lambert 《Monthly notices of the Royal Astronomical Society》2002,333(1):9-26

Effective temperatures T _eff, surface gravities log  g and interstellar extinctions A _V are found for 107 B stars. Distances d of the stars, which are based on the derived T _eff, log  g and A _V values, show good agreement with those obtained from the Hipparcos parallaxes. Comparing the T _eff and log  g values with evolutionary computations, we infer masses, radii, luminosities, ages and relative ages of the stars. Empirical relations between the T _eff and log  g parameters, on the one hand, and the photometric indices Q , [ c ₁] and β , on the other hand, are constructed; these relations give a fast method for the T _eff and log  g estimation of early and medium B stars. Inclusion of the infrared J , H and K colours into the T _eff, log  g and A _V determination shows that (i) the T _eff and log  g parameters are altered only slightly; (ii) the A _V value is rather sensitive to these colours, so an accuracy better than 0.05 mag in the JHK data is necessary for precise A _V evaluation.  相似文献   

On the relation between electron temperatures in the O⁺ and O⁺⁺ zones in high-metallicity H ii regions     

Leonid S. Pilyugin  José M. Vílchez  Trinh X. Thuan 《Monthly notices of the Royal Astronomical Society》2006,370(4):1928-1934

We suggest a new way to establish the relation between the electron temperature t ₃ within the [O  iii ] zone and the electron temperature t ₂ within the [O  ii ] zone in high-metallicity  (12 + log(O/H) > 8.25)  H  ii regions. The   t ₂– t ₃  diagram is constructed by applying our method to a sample of 372 H  ii regions. We find that the correlation between t ₂ and t ₃ is tight and can be approximated by a linear expression. The new   t ₂– t ₃  relation can be used to determine t ₂ and accurate abundances in high-metallicity H  ii regions with a measured t ₃. It can also be used in conjunction with the ff relation for the determination of t ₃ and t ₂ and oxygen abundances in high-metallicity H  ii regions, where the [O  iii ]λ4363 auroral line is not detected. The derived   t ₂– t ₃  relation is independent of photoionization models of H  ii regions.  相似文献   

Major and Trace Element Compositions of Hummocky Frozen Peatlands in the Forest–Tundra of Northeastern European Russia     

R. S. Vasilevich 《Geochemistry International》2018,56(12):1276-1288

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Fate of the Black Sea Acartia clausi and Acartia tonsa (Copepoda) penetrating into the Marmara Sea through the Bosphorus     

Elena Hubareva  Leonid Svetlichny  Ahmet Kideys  Melek Isinibilir 《Estuarine, Coastal and Shelf Science》2008

In October 2005 spatial distribution of live and dead Acartia clausi and Acartia tonsa was studied in the Black and Marmara Seas and near the Marmara Sea inlet of the Bosphorus, in order to understand their fate upon transportation between two seas. The morphometric characteristics in both species from all studied areas, and the decreased abundance of A. clausi and A. tonsa from the Black Sea towards the Marmara Sea indicate that the Marmara Sea Acartia populations are formed by recruitment from the Black Sea. We observed mass mortality of A. clausi in the Marmara Sea near the Prince Islands. The majority of carcasses (66% of total A. clausi numbers in the Marmara Sea) were found in the salinity gradient layer.  相似文献   

Hydrogen sulfide and other reduced forms of sulfur in oxic waters of Lake Doroninskoe,eastern Transbaikalia     

L. V. Zamana  S. V. Borzenko 《Doklady Earth Sciences》2007,417(1):1268-1271

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A new natural,super-hard,transparent polymorph of carbon from the Popigai impact crater,Russia   总被引：1，自引：0，他引：1  

Ahmed El Goresy  Leonid S Dubrovinsky  Philippe Gillet  Smail Mostefaoui  Günther Graup  Michael Drakopoulos  Alexandre S Simionovici  Varghese Swamy  Victor L Masaitis 《Comptes Rendus Geoscience》2003,335(12):889-898

A natural shockwave event led to the formation of a new crystalline polymorph of carbon in gneisses from the Popigai crater, Russia. The new species occupies the interior of a multiphase assemblage and is entirely enveloped by lonsdaleite and graphite. Polishing hardness of this new phase is greater than that of lonsdaleite. Micro-beam synchrotron X-ray diffraction, imaging and fluorescence studies revealed a pure transparent carbon phase. The diffraction pattern is indexed in terms of a cubic cell (a=14.697 Å, space group Pm3m.). This species was neither encountered in static or dynamic high-pressure experiment nor predicted by theoretical calculations. To cite this article: A. El Goresy et al., C. R. Geoscience 335 (2003).  相似文献   

Mineral equilibria in mantle-derived rocks     

Leonid Perchuk  Tibor Gasparik   《Lithos》2002,60(3-4):vii

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Complexation of Gold(III)-Chloride at the Surface of Hematite     

Olga N. Karasyova  Lyudmila I. Ivanova  Leonid Z. Lakshtanov  Lars Lövgren  Staffan Sjöberg 《Aquatic Geochemistry》1998,4(2):215-231

The acid/base properties of the hematite/water interface and surfacecomplexation with gold has been studied by potentiometric titrations in thefour component system H⁺ – FeOH –AuCl ₄ ^- – Cl^-. Equilibrium measurementswere performed in NaCl media at 298.2 K. In the evaluation of equilibriummodel from experimental data the constant capacitance model was applied. Theacid/base properties were investigated in 0.1 M NaCl in the range 2.6 pH 7.4. The resulting intrinsic constants for protonation anddeprotonation of hydroxyl groups at the surface were log _1,1,0,0(int) ^s = 7.10 ± 0.06 andlog _{-1,1,0,0(int)} ^s = - 7.80 ±0.06. The density of proton active surface sites was 2.85nm^-2 and the specific capacitance 2.5 C V^-1 m^-2. In the investigation of surface complexation of gold, thepotentiometric titrations were performed in the range 2.0 pH 10.2.Titration data was supplemented with analysis of Au in the aqueous phase byatomic absorbance spectrometry. The equilibrium model proposed consists ofthe following monodentate surface complexes: FeOHAuCl₃(log _0,1,1,-1 ^s = 1.45 ± 0.03),FeOHAuCl₂OH (log _-1,1,1,-2 ^s = -3.89 ± 0.02), FeOHAu(OH)₃ (log _-3,1,1,-4 ^s = -21.94 ± 0.05). Aslightly better fit could be obtained by assuming formation of a bidentatecomplex with the composition(FeO)₂Au(OH)H₂O. However, based onstructural arguments this complex was rejected.  相似文献   

High-pressure and high-temperature in situ X-ray diffraction study of iron and corundum to 68 GPa using an internally heated diamond anvil cell   总被引：1，自引：1，他引：0  

Leonid S. Dubrovinsky  Surendra K. Saxena  Peter Lazor 《Physics and Chemistry of Minerals》1998,25(6):434-441

Using powder X-ray diffraction of heated solids to pressures reaching 68 GPa, the pressure-volume-temperature (PVT) data on corundum Al₂O₃ and ɛ-Fe were determined with the following results: *Corundum,*Iron, *Al₂O₃*ɛ-Fe Isothermal bulk*258 (2)*164 (3)  modulus K'_{300, 1} (GPa) Pressure derivative K_{300, 1}*4.88 (4)*5.36 (16) Temperature derivative*–0.020 (2)*–0.043 (3)  (∂K _T,1 /∂T) _P (GPa/K) Molar volume V_300,1*25.59 (2)*6.76 (2)  (cm³/mol) Isobaric thermal expansion at 1 atm (0.101 MPa) is given by (K^–1): α _T =2.6 (2) 10^–5+1.81 (9) 10^–9 T–0.67 (6)/T ² for corundum, and α _T =5.7 (4) 10^–5+4.2 (4) 10^–9 T–0.17 (7)/T ² for iron ɛ-Fe. Received: 1 March 1997 / Revised, accepted: 21 August 1997  相似文献