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   

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   

Numerical modeling of EM fields over local anomalies with a vertical axis of symmetry     

Michael S. Zhdanov  Vjacheslav V. Spichak  Leonid Yu. Zaslavsky 《Physics of the Earth and Planetary Interiors》1990,60(1-4):53-61

A method for numerical modeling of quasi-stationary electromagnetic fields in axially symmetric media is proposed. It is based on the direct finite-element method and the use of special basis functions. Assuming cylindrical coordinates r, φ, z, the three-dimensional solution is presented as a superposition of fields with the azimuthal dependence exp(inφ). For each case this results in a system of two equations of elliptical type in two scalar functions in the (r, z) plane.

The discretization leads to the conservative nine-points difference scheme. The system of linear equations is solved by means of the LU-decomposition technique, the band structure of the matrix being taken into account.

The program is tested using analytical results (DC asymptote) for a near-surface inhomogeneity. Comparison also is made with 2D results (H-polarization) for the model of a local well conducting inclusion in a three-layered Earth.  相似文献   

A Set of Far East Magmatic Rock Reference Samples: DV     

Leonid A. BERKOVITS  Alexander K. PARSHIN 《Geostandards and Geoanalytical Research》1991,15(1):67-76

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滇东北麻栗坪铅锌矿床微量元素分布与赋存状态:LA-ICPMS研究   总被引：4，自引：2，他引：2  

胡宇思  叶霖  黄智龙  李珍立  韦晨  Danyushevskiy Leonid 《岩石学报》2019,35(11):3477-3492

位于扬子板块西南缘的"川滇黔接壤铅锌矿集区"是我国西南大面积低温成矿域的重要组成部分,麻栗坪铅锌矿床位于该矿集区昭通-曲靖成矿带中段,是近年来滇东北地区新发现的铅锌矿床。本文以麻栗坪铅锌矿不同硫化物为研究对象,通过LA-ICPMS原位点测试和元素Mapping分析,尝试揭示该矿床中Ge、Cd和In等微量元素在不同硫化物中分布规律与赋存状态。本次研究发现,麻栗坪矿床不同硫化物中富集的微量元素明显不同,闪锌矿主要富集Mn、Cu、Sn、Cd、In和Ge,而方铅矿主要富集Ag、Sb和Se,黄铁矿则富集As、Co和Ni。闪锌矿是分散元素Ge、In和Cd的主要载体矿物,且Cd、Ge、In、Mn、As、Sb和Ag以类质同象形式赋存于闪锌矿中;而Cu则主要以类质同象形式存在,部分Cu以黄铜矿的显微包裹体形式赋存于闪锌矿中,其中以类质同象赋存于闪锌矿中Cu和Ge呈现明显的相关性,可能暗示其与Zn的置换方式为:3Zn2+Ge4++2Cu+。总体上,该矿床闪锌矿以富集Cd、Ge,贫Fe、Mn、Co、Sn为特征,这些微量元素组成与典型MVT型矿床基本一致,明显有别于喷流沉积和岩浆热液型矿床,而与中低温条件下形成的闪锌矿微量元素组成相似。结合该矿床后生成矿特征明显等地质地球化学研究成果,我们认为该矿床应属于MVT型铅锌矿床。值得注意的是,该矿床闪锌矿相对富集In,可能暗示其形成具有特殊性,这可能与其成矿流体在长距离运移过程中所流经地层有关,该类流体活化萃取了基底地层的中-酸性岩浆岩或火山碎屑岩中的In,致使矿床中闪锌矿相对富集In。  相似文献