Experimental and theoretical study of the vibrational properties of diaspore (α-AlOOH)     

Simon?Delattre  Etienne?BalanEmail author  Michele?Lazzeri  Marc?Blanchard  Maxime?Guillaumet  Olivier?Beyssac  Eiken?Haussühl  Bj?rn?Winkler  Ekhard?K.?H.?Salje  Georges?Calas 《Physics and Chemistry of Minerals》2012,39(2):93-102

Vibrational properties of diaspore, α-AlOOH, have been re-investigated using room-temperature single-crystal Raman spectroscopy and low-temperature powder infrared (IR) transmission spectroscopy. First-principles harmonic calculations based on density functional theory provide a convincing assignment of the major Raman peaks and infrared absorption bands. The large width of the Raman band related to OH stretching modes is ascribed to mode–mode anharmonic coupling due to medium-strength H-bonding. Additional broadening in the powder IR spectrum arises from depolarization effects in powder particles. The temperature dependence of the IR spectrum provides a further insight into the anharmonic properties of diaspore. Based on their frequency and temperature behavior, narrow absorption features at ~2,000 cm⁻¹ and anti-resonance at ~2,966 cm⁻¹ in the IR spectrum are interpreted as overtones of fundamental bending bands.  相似文献   

Mineralium Deposita: change and continuity     

Georges Beaudoin  Bernd Lehmann 《Mineralium Deposita》2012,47(8):835-836

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Cosmogenic Be dating of a sackung and its faulted rock glaciers, in the Alps of Savoy (France)     

Jean-Claude Hippolyte  Didier Bourls  Rgis Braucher  Julien Carcaillet  Laëtitia Lanni  Maurice Arnold  Georges Aumaitre 《Geomorphology》2009,108(3-4):312-320

Sackungs are the largest gravitational deformation observed in mountains. They are characterized by the long-term slowness of the movements, but their mechanism is still not well understood. Nowadays cosmic ray exposure (CRE) dating methods allow dating the morphologic structures involved in sackung and can contribute at the understanding of their origin. In the Alps, the 5.3 km long Arcs sackung initiated during the activity of rock glaciers. Three samples from these faulted rock glaciers provide their first CRE ages and show that at 2000 m elevation these block accumulations moved during the Younger Dryas and stopped in early Holocene. Six ¹⁰Be ages of fault scarps show that the Arcs sackung lasted only a few thousand years and stopped at about 8462 ± 432 ¹⁰Be yr. They also reveal that deformation migrated upslope in agreement with a mechanism of flexural toppling of vertical layers. This unique and long gravitational event, characterized by migration of the deformation, does not support earthquake shaking as triggering mechanism for individual faults. It shows that, in the upper Isère valley, slope deformation was delayed of several thousand years after glacial debuttressing, and is not anymore active despite its fresh morphology.  相似文献   

Messinian deposits and erosion in northern Tunisia: inferences on Strait of Sicily during the Messinian Salinity Crisis     

Narjess El Euch-El Koundi  Serge Ferry  Jean-Pierre Suc  Georges Clauzon  Mihaela Carmen Melinte-Dobrinescu  Christian Gorini  Anissa Safra  Fouad Zargouni 《地学学报》2009,21(1):41-48

Outcrops, offshore wells, electric logs and seismic profiles from northern Tunisia provide an opportunity to decipher the Messinian Salinity Crisis in the Strait of Sicily. Messinian deposits (including gypsum beds) near the Tellian Range reveal two successive subaerial erosional surfaces overlain by breccias and marine Zanclean clays, respectively. In the Gulf of Tunis, Messinian thick evaporites (mostly halite) are strongly eroded by a fluvial canyon infilled with Zanclean clays. The first erosional phase is referred to the intra-Messinian tectonic phase and is analogous to that found in Sicily. The second phase corresponds to the Messinian Erosional Surface that postdates the marginal evaporites, to which the entire Sicilian evaporitic series must refer. The Western and Eastern Mediterranean basins were separated during deposition of the central evaporites.  相似文献   

Carbon Isotope Analysis to Evaluate Nanoscale Fe(O) Treatment at a Chlorohydrocarbon Contaminated Site     

Martin Elsner  Georges Lacrampe Couloume  Silvia Mancini  Leanne Burns  Barbara Sherwood Lollar 《Ground Water Monitoring & Remediation》2010,30(3):79-95

Remediation of groundwater contaminated by chlorinated hydrocarbons via in situ technologies such as direct injection of nanoscale zero valent iron (ZVI, Fe(O)) particles is increasingly common. However, assessing target compound degradation by abiotic processes is difficult because (1) the injection may displace the contaminant plume so that concentration measurements alone are often inconclusive and (2) biodegradation may also occur, making it challenging to identify and evaluate the abiotic degradation component. In this study, trichloroethylene (TCE) and 1,1,1-trichloroethane (1,1,1-TCA) were treated in a highly heterogeneous hydrogeologic setting. The purpose of this study was to evaluate the potential for compound-specific stable isotope analysis (CSIA) to monitor the effectiveness of ZVI injection by assessing TCE and 1,1,1-TCA degradation. Prior to ZVI injection, carbon isotope measurements demonstrated biodegradation of TCE by native microorganisms. This in situ biodegradation was quantified by measuring the enrichment of ¹³C in TCE samples downstream of the suspected source. When ZVI was injected through only two injection wells, no changes in TCE and 1,1,1-TCA isotope signatures were detected compared to preinjection values. In contrast, when ZVI was injected through 11 wells covering a greater portion of the contaminated area, 5 out of 10 monitoring wells showed further enrichment of ¹³C in either TCE or 1,1,1-TCA, indicating additional target compound transformation. The abiotic nature of this TCE transformation was confirmed through temporal trends in carbon isotope values of the putative transformation products cis-dichloroethylene (cis-DCE), ethene and ethane. This demonstrates the usefulness of CSIA in distinguishing abiotic vs. biotic transformation in the field.  相似文献   

Experimental investigation on a base isolation system incorporating steel–Teflon sliders and pressurized fluid viscous spring dampers     

Stefano Sorace  Gloria Terenzi  Georges Magonette  Francisco J. Molina 《地震工程与结构动力学》2008,37(2):225-242

An experimental investigation on a base isolation system incorporating stainless steel–Teflon bearings as sliders, and pressurized fluid viscous spring dampers, is presented in this paper. In the system examined, dampers are connected to the base floor of an isolated building to provide the desired passive control of response in the superstructure, as well as to guarantee that it re‐centres completely after the termination of a seismic action. Two types of experiments were conducted: sinusoidal and random cyclic tests, and a pseudodynamic test in ‘substructured’ configuration. The cyclic tests were aimed at characterizing what follows: the hysteretic and strain‐rate‐dependent response of the considered highly non‐linear spring dampers; the normal pressure‐ and strain‐rate‐dependent frictional behaviour of steel–Teflon bearings, manufactured in compliance with the latest standards for this class of sliders; and the combined response of their assembly. The pseudodynamic test simulated the installation of the protection system at the base of a 2:3‐scale three‐storey steel frame structure, already tested in unprotected conditions by an earlier experimental campaign. Among other findings, the results of the performed tests, as well as of relevant mechanical interpretation and numerical simulation analyses, confirmed the linear additive combination of the dissipative actions of spring dampers and sliders in this mixed installation, and the high protective performance of the considered base isolation/supplemental damping system in a realistic earthquake simulation. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Urban integration of Israeli immigrants in the 1990s: a comparison of Be'er Sheva, Ashkelon, Kiriat Gat     

Colette Aymard  Georges Benko 《GeoJournal》1998,44(4):321-336

As a result of the opening of the borders of the former Soviet Union, Israel has been the destination of numerous immigrants. This article deals with the impact of immigration between 1989 and 1994, upon three towns in the south of Israel, Be'er Sheva, Ashkelon and Kiriat Gat. These towns correspond to three socio-economic levels of urban area in the southern region. On the one hand, the immigrants from the former Soviet Union arrive with specific demands, on the other hand the political, economical and social context in Israel is very unusual. The sucessful integration of immigrants and the constructive development of the host country depend on the conformity of these demands and proposals. What the government offers in terms of housing, reception and employment in each of the three towns plays a key role: the town's social and economical heritage influences the integration of the new population while at the same time the arrival of a new workforce influences the development of the local area. Every town wants to grow and reinforce its position in the region, but only the large town, Be'er Sheva, is able to offer a certain diversity and therefore answers more fully the needs and wants of this new population. Government decisions and policies are not made to oppose the liberal economic system and to suppress the spacial inequalities despite some measures aiming at a more equal balance. The importance of heritage and the lack of communal development schemes within regions together ensure the continuation of qualitative inegalities in the south of Israel and even accentuate the problem. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

An 'Ionospheric Weather' Index     

T. M. Georges 《Geophysical Journal International》1971,26(1-4):243-245

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The giant clam Tridacna maxima communities of three French Polynesia islands: comparison of their population sizes and structures at early stages of their exploitation     

Gilbert  Antoine; Andrefouet  Serge; Yan  Laurent; Remoissenet  Georges 《ICES Journal of Marine Science》2006,63(9):1573-1589

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Accretion and tectono-sedimentary progradation: The Taranto Gulf (Southern Italy)     

Georges Mascle  Jean Mascle 《Geo-Marine Letters》1983,3(1):9-12

The geological structures of the eastern Calabrian Apenninic front within the Gulf of Taranto, southern Italy, are compared to those of a convergent margin, using simple criteria such as the origin and volume of the sediment supply, and the relative ratio between sediments carried by the sinking plate and those directly supplied by the overriding margin. Based on this criteria we distinguish four main types of sedimentary accretion occurring at convergent continental margins: (a) Pacific type, (b) Indonesian type, (c) Caribbean type, and (d) Apenninic type.  相似文献