Approximate formulas for dynamic stiffnesses of rigid foundations   总被引：3，自引：0，他引：3  

Artur Pais  Eduardo Kausel 《Soil Dynamics and Earthquake Engineering》1988,7(4):213-227

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Stability of biomass-derived black carbon in soils   总被引：16，自引：0，他引：16  

Biqing Liang  Dawit Solomon  Janice E. Thies  Flavio J. Luizão  Eduardo G. Neves 《Geochimica et cosmochimica acta》2008,72(24):6069-6078

Black carbon (BC) may play an important role in the global C budget, due to its potential to act as a significant sink of atmospheric CO₂. In order to fully evaluate the influence of BC on the global C cycle, an understanding of the stability of BC is required. The biochemical stability of BC was assessed in a chronosequence of high-BC-containing Anthrosols from the central Amazon, Brazil, using a range of spectroscopic and biological methods. Results revealed that the Anthrosols had 61-80% lower (P < 0.05) CO₂ evolution per unit C over 532 days compared to their respective adjacent soils with low BC contents. No significant (P > 0.05) difference in CO₂ respiration per unit C was observed between Anthrosols with contrasting ages of BC (600-8700 years BP) and soil textures (0.3-36% clay). Similarly, the molecular composition of the core regions of micrometer-sized BC particles quantified by synchrotron-based Near-Edge X-ray Fine Structure (NEXAFS) spectroscopy coupled to Scanning Transmission X-ray Microscopy (STXM) remained similar regardless of their ages and closely resembled the spectral characteristics of fresh BC. BC decomposed extremely slowly to an extent that it was not possible to detect chemical changes between youngest and oldest samples, as also confirmed by X-ray Photoelectron Spectroscopy (XPS). Deconvolution of NEXAFS spectra revealed greater oxidation on the surfaces of BC particles with little penetration into the core of the particles. The similar C mineralization between different BC-rich soils regardless of soil texture underpins the importance of chemical recalcitrance for the stability of BC, in contrast to adjacent soils which showed the highest mineralization in the sandiest soil. However, the BC-rich Anthrosols had higher proportions (72-90%) of C in the more stable organo-mineral fraction than BC-poor adjacent soils (2-70%), suggesting some degree of physical stabilization.  相似文献   

Gravitational deformation and inherited structural control on slope morphology in the subduction zone of north‐central Chile (ca. 29–33°S)          下载免费PDF全文

Juan Becerra  César Arriagada  Eduardo Contreras‐Reyes  Sebastián Bascuñan  Gregory P. De Pascale  Christian Reichert  Juan Díaz‐Naveas  Natalia Cornejo 《Basin Research》2017,29(6):798-815

Subduction zones provide direct insight into plate boundary deformation and by studying these areas we better understand tectonic processes and variability over time. We studied the structure of the offshore subduction zone system of the Pampean flat‐slab segment (ca. 29–33°S) of the Chilean margin using seismic and bathymetric constraints. Here, we related and analysed the structural styles of the offshore and onshore western fore‐arc. Overlying the acoustic top of the continental basement, two syn‐extensional seismic sequences were recognised and correlated with onshore geological units and the Valparaíso Forearc Basin seismic sequences: (SII) Pliocene‐Pleistocene and (SI) Miocene‐Pliocene (Late Cretaceous (?) to Miocene‐Pliocene) syn‐extensional sequences. These sequences are separated by an unconformity (i.e. Valparaíso Unconformity). Seismic reflection data reveal that the eastward dipping extensional system (EI) recognised at the upper slope can be extended to the middle slope and controlled the accumulation of the older seismic package (SI). The westward dipping extensional system (EII) is essentially restricted to the middle slope. Here, EII cuts the eastward dipping extensional system (EI), preferentially parallel to the inclination of the older sequences (SI), and controlled a series of middle slope basins which are filled by the Pliocene‐Pleistocene seismic sequence (SII). At the upper slope and in the western Coastal Cordillera, the SII sequence is controlled by eastward dipping faults (EII) which are the local reactivation of older extensional faults (EI). The tectonic boundary between the middle (eastern outermost forearc block) and upper continental slope (western coastal block) is a prominent system of trenchward dipping normal fault scarps (ca. 1 km offset) that resemble a major trenchward dipping extensional fault system. This prominent structural feature can be readily detected along the Chilean erosive margin as well as the two extensional sets (EI and EII). Evidence of slumping, thrusting, reactivated faults and mass transport deposits, were recognised in the slope domain and locally restricted to some eastern dipping faults. These features could be related to gravitational effects or slope deformation due to coseismic deformation. The regional inclination of the pre‐Pliocene sequences favoured the gravitational collapse of the outermost forearc block. We propose that the structural configuration of the study area is dominantly controlled by tectonic erosion as well as the uplift of the Coastal Cordillera, which is partially controlled by pre‐Pliocene architecture.  相似文献   

Sedimentary record of the northward flight of India and its collision with Eurasia (Ladakh Himalaya,India)     

Eduardo Garzanti  Aymon Baud  Georges Mascle 《Geodinamica Acta》2013,26(4-5):297-312

Abstract

— Stratigraphic and petrographic analysis of the Cretaceous to Eocene Tibetan sedimentary succession has allowed us to reinterpret in detail the sequence of events which led to closure of Neotethys and continental collision in the NW Himalaya.

During the Early Cretaceous, the Indian passive margin recorded basaltic magmaüc activity. Albian volcanic arenites, probably related to a major extensional tectonic event, are unconformably overlain by an Upper Cretaceous to Paleocene carbonate sequence, with a major quartzarenite episode triggered by the global eustatic sea-level fall at the Cretaceous/Tertiary boundary. At the same time, Neotethyan oceanic crust was being subducted beneath Asia, as testified by calc-alkalic volcanism and forearc basin sedimentation in the Transhimalayan belt.

Onset of collision and obduction of the Asian accretionary wedge onto the Indian continental rise was recorded by shoaling of the outer shelf at the Paleocene/Eocene boundary, related to flexural uplift of the passive margin. A few My later, foreland basin volcanic arenites derived from the uplifted Asian subduction complex onlapped onto the Indian continental terrace. All along the Himalaya, marine facies were rapidly replaced by continental redbeds in collisional basins on both sides of the ophiolitic suture. Next, foreland basin sedimentation was interrupted by fold-thrust deformation and final ophiolite emplacement.

The observed sequence of events compares favourably with theoretical models of rifted margin to overthrust belt transition and shows that initial phases of continental collision and obduction were completed within 10 to 15 My, with formation of a proto-Himalayan chain by the end of the middle Eocene.  相似文献   

Copper Biosorption by Spent Coffee Ground: Equilibrium,Kinetics, and Mechanism     

Nancy Elizabeth Dávila‐Guzmán  Felipe de Jesús Cerino‐Córdova  Eduardo Soto‐Regalado  Jose Rene Rangel‐Mendez  Paola Elizabeth Díaz‐Flores  Maria Teresa Garza‐Gonzalez  José Angel Loredo‐Medrano 《洁净——土壤、空气、水》2013,41(6):557-564

The potential use of spent coffee ground (SCG) for the removal of copper has been investigated as a low‐cost adsorbent for the biosorption of heavy metals. Adsorption batch experiments were conducted to determine isotherms and kinetics. The biosorption equilibrium data were found to fit well the Freundlich model and an experimental maximum biosorption capacity of copper ions 0.214 mmol/g was achieved. The biosorption kinetics of SCG was studied at different adsorbate concentrations (0.1–1.0 mM) and stirring speeds (100–400/min). The results showed an increase in the copper ion uptake with raising the initial metal concentration and the kinetic data followed the pseudo‐second order rate expression. The effect of stirring speed was a significant factor for the external mass transfer resistance at 100/min and coefficients were estimated by the Mathews and Weber model. Biosorption of copper ions onto SCG was observed to be related mainly with the release of calcium and hydrogen ions suggesting that biosorption performance by SCG can be attributed to ion‐exchange mechanism with calcium and hydrogen ions neutralizing the carboxyl and hydroxyl groups of the biomass.  相似文献   

Removal of Carbamazepine,Naproxen, and Trimethoprim from Water by Amberlite XAD‐7: A Kinetic Study     

Joaquín R. Domínguez‐Vargas  Teresa Gonzalez  Patricia Palo  Eduardo M. Cuerda‐Correa 《洁净——土壤、空气、水》2013,41(11):1052-1061

The adsorption kinetics of carbamazepine, naproxen, and trimethoprim in aqueous solution by Amberlite? XAD‐7 has been studied. The influence of adsorbent dose (1–3 g/L), stirring rate (80–240 rpm), pH (2–9), temperature (20–60°C), and initial concentration (25–75 ppm) on the adsorption kinetics has been analyzed. The removal efficiency in the first 2 h reaches 85% for carbamazepine, 60% for naproxen, and 70% for trimethoprim. pH appears to be the most important factor conditioning the removal of these latter solutes, whereas carbamazepine adsorption seems to be independent of the pH of the adsorptive solution. Initial concentration and operation temperature moderately influence the adsorption process. Finally, stirring rate scarcely affects the process. The experimental data have been fitted to four kinetic models, namely pseudo‐first and pseudo‐second order, intra‐particle diffusion and Bangham's. The model providing the best fit is the pseudo‐second order one. Again, pH is the factor that affects the adsorption rate in a more remarkable manner although other parameters such as temperature and stirring rate also contribute to accelerate the removal of the solutes. Under the optimal operation conditions, Amberlite? XAD‐7 exhibits a promising ability for the removal of the pharmaceuticals under study.  相似文献   

The Need for Ultraviolet to Understand the Chemical Evolution of the Universe and Cosmology.     

Willem Wamsteker  Jason X. Prochaska  Luciana Bianchi  Dieter Reimers  Nino Panagia  Andrew C. Fabian  Claes Fransson  Boris M. Shustov  Patrick Petitjean  Phillipp Richter  Eduardo Battaner 《Astrophysics and Space Science》2006,303(1-4):69-84

We identify an important set of key areas where an advanced observational Ultraviolet capability would have major impact on studies of cosmology and Galaxy formation in the young Universe. Most of these are associated with the Universe at z < 3–4. We address the issues associated with Dark matter evidence in the local Universe and the impact of the Warm-Hot Intergalactic Medium WHIM on the local Baryon count. The motivations to make ultraviolet (UV) studies of supernovae (SNe) are reviewed and discussed in the light of the results obtained so far by means of IUE and HST observations. It appears that UV studies of SNe can, and do lead to fundamental results not only for our understanding of the SN phenomenon, such as the kinematics and the metallicity of the ejecta, but also for exciting new findings in Cosmology, such as the tantalizing evidence for “dark energy” that seems to pervade the Universe and to dominate its energetics. The need for additional and more detailed UV observations is also considered and discussed.Finally we show the enormous importance of the UV for abundance evolution in the Intergalactic Medium (IGM), and the importance of the He II studies to identify re-ionization epochs, which can only be done in the UV.  相似文献   

The European Large Area ISO Survey – IX. The 90-μm luminosity function from the Final Analysis sample     

Stephen Serjeant †  Alberto Carramiñana †  Eduardo Gonzáles-Solares  Phillipe Héraudeau  Raúl Mújica †  Ismael Perez-Fournon  Nicola Sedgwick †  Michael Rowan-Robinson  Alberto Franceschini  Thomas Babbedge  Carlos del Burgo  Paolo Ciliegi  reas Efstathiou  Fabio La Franca  Carlotta Gruppioni  David Hughes  Carlo Lari  Seb Oliver  Francesca Pozzi  Manfred Stickel  Mattia Vaccari 《Monthly notices of the Royal Astronomical Society》2004,355(3):813-818

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Young star clusters immersed in intermediate-age fields in the Large Magellanic Cloud bar     

Andrés E. Piatti  Doug Geisler  Eduardo Bica  Juan J. Clariá 《Monthly notices of the Royal Astronomical Society》2003,343(3):851-862

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On a universal structure for immiscible three-phase flow in virgin reservoirs     

Pablo Castañeda  Eduardo Abreu  Frederico Furtado  Dan Marchesin 《Computational Geosciences》2016,20(1):171-185

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