Effects of seed particle size and composition on heterogeneous nucleation of n-nonane     

Paul M. Winkler  Anca Hienola  Gerhard Steiner  Gerard Hill  Aron Vrtala  Georg P. Reischl  Markku Kulmala  Paul E. Wagner 《Atmospheric Research》2008,90(2-4):187-ICNAA07

Heterogeneous nucleation of supersaturated n-nonane vapour on seed particles of different size and composition has been investigated using a fast expansion chamber. Monodisperse seed particle sizes were ranging from about 4 nm up to about 24 nm in diameter. By using different types of particle generators WO_x, Ag and (NH₄)₂SO₄ particles were generated. For direct comparison between different particle compositions overlapping sizes have been generated for WO_x and Ag at about 7 nm particle diameter as well as for Ag and (NH₄)₂SO₄ at about 15 nm. Nucleation temperature was kept constant at about 278 K. Experimental data were compared to Kelvin equation and Fletcher theory including the effect of line tension. It was found that heterogeneous nucleation of n-nonane seems to be independent of seed particle composition and starts well below the Kelvin curve. Good agreement was achieved with Fletcher theory including the effect of line tension.  相似文献   

气候变化背景下欧洲中部水资源供给的不稳定性评估——以易北河流域为例   总被引：1，自引：0，他引：1       下载免费PDF全文

Joachim Post  Tobias Conradt  Frank Wechsung  高超  姜彤 《气候变化研究进展》2009,5(2):63-070

 欧洲中部的易北河流域是典型的湿润半湿润地区。夏季的水资源供给是限制农业生产的因素之一,特别是在具有较高农业生产力水平,而年降水量只有500 mm的黄土地区。通过总结气候变化与水文循环（GLOWA-Elbe）项目第一阶段的成果,根据气候和土地利用变化的各种情景并考虑其不确定性,对未来50 a德国易北河流域水资源供给稳定性作出综合评估。研究表明,欧洲中部必须从自然和社会角度应对未来气候变化情景下产生水资源供给短缺的可能情况。  相似文献   

A global landslide catalog for hazard applications: method,results, and limitations   总被引：4，自引：1，他引：3  

Dalia Bach Kirschbaum  Robert Adler  Yang Hong  Stephanie Hill  Arthur Lerner-Lam 《Natural Hazards》2010,52(3):561-575

A systematic inventory of landslide events over the globe is valuable for estimating human and economic losses, quantifying the relationship between landslide occurrences and climate variations and for evaluating emerging global landslide prediction efforts based on remote sensing data. This study compiles a landslide catalog for rainfall-triggered events for several years, drawing upon news reports, scholarly articles, and other hazard databases to provide a landslide catalog at the global scale. While this database may only represent a subset of rainfall-triggered landslides globally, due to lack of reports, it presents a lower boundary on the number of events globally and provides initial insight into the spatiotemporal statistical trends in landslide distribution and impact. This article develops a methodology for landslide event compilation that can be used in evaluating global landslide forecasting initiatives and assessing patterns in landslide distribution and frequency worldwide.  相似文献   

Reply to “Reply to comments on defining biominerals and organominerals: Direct and indirect indicators of life [Perry et al., Sedimentary Geology, 201, 157–179]” by R.S. Perry and M.A. Sephton: [Sedimentary Geology 213 (2009) 156]     

Christian Défarge  Pascale Gautret  Joachim Reitner  Jean Trichet 《Sedimentary Geology》2010,223(3-4):390-391

This is a reply to R.S. Perry and M.A. Sephton's “Reply to comments on defining biominerals and organominerals: direct and indirect indicators of life [Perry et al., Sedimentary Geology, 201, 157–179]” [Sedimentary Geology 213 (2009) 156].  相似文献   

The role of the Kupferschiefer in the formation of hydrothermal base metal mineralization in the Spessart ore district, Germany: insight from detailed sulfur isotope studies     

Thomas Wagner  Martin Okrusch  Stefan Weyer  Joachim Lorenz  Yann Lahaye  Heiner Taubald  Ralf T. Schmitt 《Mineralium Deposita》2010,45(3):217-239

The Spessart district (SW Germany), located at the southwestern margin of the Permian Kupferschiefer basin in Central Europe, hosts abundant stratabound and structurally controlled base metal mineralization. The mineralization styles identified are (1) stratabound Cu-Pb-Zn-(Ag) ores in Zechstein sedimentary rocks, (2) structurally controlled Cu-As-(Ag) ores in Zechstein sedimentary rocks, (3) crosscutting Co-Ni-(Bi)-As and Cu-Fe-As veins, (4) stratabound metasomatic Fe-Mn carbonate ores in Zechstein dolomite, (5) barren barite veins, and (6) Fe-Mn-As veins in Permian rhyolites. Building on previous work that involved mineralogical, textural, and chemical characterization of the major mineralization types, we have performed a comprehensive sulfur isotope study that applied both conventional and novel laser-ablation multi-collector inductively coupled plasma mass spectrometry techniques. The δ³⁴S values of sulfide minerals from the different ore types are consistently negative and highly variable, in the range between −44.5‰ and −3.9‰, whereas the δ³⁴S values of barite are all positive in the range between 4.7‰ and 18.9‰. Remarkably, stratabound and structurally controlled mineralization in Zechstein sedimentary rocks has the least negative δ³⁴S values, whereas vein-type deposits have consistently more negative δ³⁴S values. The observed pattern of sulfide δ³⁴S values can be best interpreted in terms of fluid mixing at the basement-cover interface. Hydrothermal fluids originating from the crystalline basement migrated upward along subvertical fault zones and were periodically injected into groundwaters that were flowing in the post-Variscan sedimentary cover. These groundwaters had interacted with the Zechstein sedimentary rocks, resulting in fluids characterized by elevated concentrations of reduced sulfur (with negative δ³⁴S values) and alkaline pH. Repeated mixing between both chemically contrasting fluids caused rapid and efficient precipitation of sulfide ore minerals in hydrothermal veins with highly variable but distinctly negative δ³⁴S values.  相似文献   

Negative ions in the Enceladus plume     

A.J. Coates  G.H. Jones  G.R. Lewis  A. Wellbrock  D.T. Young  R.E. Johnson  T.W. Hill 《Icarus》2010,206(2):618-622

During Cassini’s Enceladus encounter on 12th March 2008, the Cassini Electron Spectrometer, part of the CAPS instrument, detected fluxes of negative ions in the plumes from Enceladus. It is thought that these ions include negatively charged water group cluster ions associated with the plume and forming part of the ‘plume ionosphere’. In this paper we present our observations, argue that these are negative ions, and present preliminary mass identifications. We also suggest mechanisms for production and loss of the ions as constrained by the observations. Due to their short lifetime, we suggest that the ions are produced in or near the water vapour plume, or from the extended source of ice grains in the plume. We suggest that Enceladus now joins the Earth, Comet Halley and Titan as locations in the Solar System where negative ions have been directly observed although the ions observed in each case have distinctly different characteristics.  相似文献   

3D model of fracture zones at Soultz-sous-Forêts based on geological data,image logs,induced microseismicity and vertical seismic profiles     

Judith Sausse  Chrystel Dezayes  Louis Dorbath  Albert Genter  Joachim Place 《Comptes Rendus Geoscience》2010,342(7-8):531-545

This study presents a new deterministic 3D model of the fracture zones observed in the granitic reservoir of the Soultz European geothermal project. The major fracture zones encountered around 6 wells (4550, EPS1, GPK1, GPK2, GPK3 and GPK4) consist in 53 main structures that are located and characterized in terms of size and orientation: 39 fracture zones, 8 microseismic structures and 6 structures derived from vertical seismic profiles are represented in the 3D model using Discrete Fracture Network tools of the gOcad modelling platform (Paradigm?, Earth Decision?). This work illustrates the complexity of 3D fracture zone correlation and interpretation in crystalline rock masses characterized at meter scale (borehole) and at the reservoir scale (kilometer) thanks to geophysical imaging techniques.  相似文献   

Physical properties of fault zones within a granite body: Example of the Soultz-sous-Forêts geothermal site     

Yves Géraud  Michel Rosener  Fabrice Surma  Joachim Place  Édouard Le Garzic  Marc Diraison 《Comptes Rendus Geoscience》2010,342(7-8):566-574

In EGS projects, fault zones are considered as the structures controlling deep flow at the reservoir scale. Using a large set of petrophysical properties (porosity, density, permeability, thermal conductivity [TC]) measured on cores collected along the EPS-1 borehole, a model of fault zone is proposed to describe them. A fault zone is a complex structure, showing different parts with different kinds of deformations and/or materials that could explain chemical and physical processes observed during fluid-rock interactions. The different parts composing the fault zone are: (1) the fault core or gauge zone; (2) the damage zone; (3) and the protolith. They are usually heterogeneous and show different physical properties. The damage zone is a potential high permeability channel and could become the main pathway for fluids if secondary minerals seal the fault core. Porosity is the lowest within the protolith, between 0.5 and 1%, but can go up to 15% in the fault zone. Permeability ranges from 10^?20 m² in the fresh granite to, at least, 10^?15 m² in the fault core, and TC ranges from 2.5 W K^?1m^?1 to 3.7 W K^?1m^?1. Finally, variations in specific surface are set over two orders of magnitude. If the lowest values usually characterize the fresh granite far from fault zones, physical properties could show variations spread over their whole respective ranges within these fault zones.  相似文献   

Towards an understanding of the Of?p star HD 191612: optical spectroscopy   总被引：1，自引：0，他引：1  

Ian D. Howarth  Nolan R. Walborn  Danny J. Lennon  Joachim Puls  Yaël Nazé  K. Annuk  I. Antokhin  D. Bohlender  H. Bond  J.-F. Donati  L. Georgiev  D. Gies  D. Harmer  A. Herrero  I. Kolka  D. McDavid  T. Morel  I. Negueruela  G. Rauw  P. Reig 《Monthly notices of the Royal Astronomical Society》2007,381(2):433-446

We present extensive optical spectroscopy of the early-type magnetic star HD 191612 (O6.5f?pe–O8fp). The Balmer and He  i lines show strongly variable emission which is highly reproducible on a well-determined 538-d period. He  ii absorptions and metal lines (including many selective emission lines but excluding He  ii λ4686 Å emission) are essentially constant in line strength, but are variable in velocity, establishing a double-lined binary orbit with   P _orb= 1542 d, e = 0.45  . We conduct a model-atmosphere analysis of the spectrum, and find that the system is consistent with a ∼O8 giant with a ∼B1 main-sequence secondary. Since the periodic 538-d changes are unrelated to orbital motion, rotational modulation of a magnetically constrained plasma is strongly favoured as the most likely underlying 'clock'. An upper limit on the equatorial rotation is consistent with this hypothesis, but is too weak to provide a strong constraint.  相似文献   

Microlensing of central images in strong gravitational lens systems     

Gregory Dobler  Charles R. Keeton  Joachim Wambsganss 《Monthly notices of the Royal Astronomical Society》2007,377(3):977-986

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