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Author Stien, D.; Gastaldi, S.
Title Design of polyaromatic hydrocarbon-supported tin reagents: A new family of tin reagents easily removable from reaction mixtures Type Journal Article
Year 2004 Publication Journal of Organic Chemistry Abbreviated Journal J. Org. Chem.
Volume 69 Issue 13 Pages (down) 4464-4470
Keywords
Abstract We report in this paper the preparation and use of stannanes 11, 12a, and 12b, compounds whose 3-pyrenylpropyl side chain affinity for activated carbon simplifies tin removal and product isolation. Our pyrene-supported reagents can be used for radical reductions and cyclizations (11), radical and cationic allylations (12a), and Stille couplings (12b) in much the same way as tributyltin derivatives.
Address CNRS UPS 2561, Cayenne 97300, French Guiana, Email: didier.stien@guyane.cnrs.fr
Corporate Author Thesis
Publisher AMER CHEMICAL SOC Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-3263 ISBN Medium
Area Expedition Conference
Notes ISI:000222187200022 Approved no
Call Number EcoFoG @ eric.marcon @ Serial 263
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Author Almeras, T.; Derycke, M.; Jaouen, G.; Beauchene, J.; Fournier, M.
Title Functional diversity in gravitropic reaction among tropical seedlings in relation to ecological and developmental traits Type Journal Article
Year 2009 Publication Journal of Experimental Botany Abbreviated Journal J. Exp. Bot.
Volume 60 Issue 15 Pages (down) 4397-4410
Keywords Biomechanics; French Guiana; functional diversity; gravitropism; reaction wood; tropical rainforest
Abstract Gravitropism is necessary for plants to control the orientation of their axes while they grow in height. In woody plants, stem re-orientations are costly because they are achieved through diameter growth. The functional diversity of gravitropism was studied to check if the mechanisms involved and their efficiency may contribute to the differentiation of height growth strategies between forest tree species at the seedling stage. Seedlings of eight tropical species were grown tilted in a greenhouse, and their up-righting movement and diameter growth were measured over three months. Morphological, anatomical, and biomechanical traits were measured at the end of the survey. Curvature analysis was used to analyse the up-righting response along the stems. Variations in stem curvature depend on diameter growth, size effects, the increase in self-weight, and the efficiency of the gravitropic reaction. A biomechanical model was used to separate these contributions. Results showed that (i) gravitropic movements were based on a common mechanism associated to similar dynamic patterns, (ii) clear differences in efficiency (defined as the change in curvature achieved during an elementary diameter increment for a given stem diameter) existed between species, (iii) the equilibrium angle of the stem and the anatomical characters associated with the efficiency of the reaction also differed between species, and (iv) the differences in gravitropic reaction were related to the light requirements: heliophilic species, compared to more shade-tolerant species, had a larger efficiency and an equilibrium angle closer to vertical. This suggests that traits determining the gravitropic reaction are related to the strategy of light interception and may contribute to the differentiation of ecological strategies promoting the maintenance of biodiversity in tropical rainforests.
Address [Almeras, Tancrede; Derycke, Morgane; Jaouen, Gaelle] INRA, UMR Ecol Forets Guyane, F-97310 Kourou, France, Email: t_almeras@hotmail.com
Corporate Author Thesis
Publisher OXFORD UNIV PRESS Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-0957 ISBN Medium
Area Expedition Conference
Notes ISI:000271389400017 Approved no
Call Number EcoFoG @ eric.marcon @ Serial 96
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Author Cachet, N.; Hoakwie, F.; Bertani, S.; Bourdy, G.; Deharo, E.; Stien, D.; Houel, E.; Gornitzka, H.; Fillaux, J.; Chevalley, S.; Valentin, A.; Jullian, V.
Title Antimalarial Activity of Simalikalactone E, a New Quassinoid from Quassia amara L. (Simaroubaceae) Type Journal Article
Year 2009 Publication Antimicrobial Agents and Chemotherapy Abbreviated Journal Antimicrob. Agents Chemother.
Volume 53 Issue 10 Pages (down) 4393-4398
Keywords
Abstract We report the isolation and identification of a new quassinoid named simalikalactone E (SkE), extracted from a widely used Amazonian antimalarial remedy made out of Quassia amara L. (Simaroubaceae) leaves. This new molecule inhibited the growth of Plasmodium falciparum cultured in vitro by 50%, in the concentration range from 24 to 68 nM, independently of the strain sensitivity to chloroquine. We also showed that this compound was able to decrease gametocytemia with a 50% inhibitory concentration sevenfold lower than that of primaquine. SkE was found to be less toxic than simalikalactone D (SkD), another antimalarial quassinoid from Q. amara, and its cytotoxicity on mammalian cells was dependent on the cell line, displaying a good selectivity index when tested on nontumorogenic cells. In vivo, SkE inhibited murine malaria growth of Plasmodium vinckei petteri by 50% at 1 and 0.5 mg/kg of body weight/day, by the oral or intraperitoneal routes, respectively. The contribution of quassinoids as a source of antimalarial molecules needs therefore to be reconsidered.
Address [Cachet, N.; Hoakwie, F.; Bourdy, G.; Deharo, E.; Chevalley, S.; Valentin, A.; Jullian, V.] Univ Toulouse, UPS, Lab Pharmacochim Subst Nat & Pharmacophores Redox, UMR 152, F-31062 Toulouse 9, France, Email: jullian@cict.fr
Corporate Author Thesis
Publisher AMER SOC MICROBIOLOGY Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0066-4804 ISBN Medium
Area Expedition Conference
Notes ISI:000270020600047 Approved no
Call Number EcoFoG @ eric.marcon @ Serial 103
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Author Longo, M.; Knox, R.G.; Levine, N.M.; Swann, A.L.S.; Medvigy, D.M.; Dietze, M.C.; Kim, Y.; Zhang, K.; Bonal, D.; Burban, B.; Camargo, P.B.; Hayek, M.N.; Saleska, S.R.; Da Silva, R.; Bras, R.L.; Wofsy, S.C.; Moorcroft, P.R.
Title The biophysics, ecology, and biogeochemistry of functionally diverse, vertically and horizontally heterogeneous ecosystems: The Ecosystem Demography model, version 2.2-Part 2: Model evaluation for tropical South America Type Journal Article
Year 2019 Publication Geoscientific Model Development Abbreviated Journal Geoscientific Model Dev.
Volume 12 Issue 10 Pages (down) 4347-4374
Keywords
Abstract The Ecosystem Demography model version 2.2 (ED-2.2) is a terrestrial biosphere model that simulates the biophysical, ecological, and biogeochemical dynamics of vertically and horizontally heterogeneous terrestrial ecosystems. In a companion paper (Longo et al., 2019a), we described how the model solves the energy, water, and carbon cycles, and verified the high degree of conservation of these properties in long-term simulations that include long-term (multi-decadal) vegetation dynamics. Here, we present a detailed assessment of the model's ability to represent multiple processes associated with the biophysical and biogeochemical cycles in Amazon forests. We use multiple measurements from eddy covariance towers, forest inventory plots, and regional remote-sensing products to assess the model's ability to represent biophysical, physiological, and ecological processes at multiple timescales, ranging from subdaily to century long. The ED-2.2 model accurately describes the vertical distribution of light, water fluxes, and the storage of water, energy, and carbon in the canopy air space, the regional distribution of biomass in tropical South America, and the variability of biomass as a function of environmental drivers. In addition, ED-2.2 qualitatively captures several emergent properties of the ecosystem found in observations, specifically observed relationships between aboveground biomass, mortality rates, and wood density; however, the slopes of these relationships were not accurately captured. We also identified several limitations, including the model's tendency to overestimate the magnitude and seasonality of heterotrophic respiration and to overestimate growth rates in a nutrient-poor tropical site. The evaluation presented here highlights the potential of incorporating structural and functional heterogeneity within biomes in Earth system models (ESMs) and to realistically represent their impacts on energy, water, and carbon cycles. We also identify several priorities for further model development.
Address Georgia Institute of Technology, Atlanta, GA, United States
Corporate Author Thesis
Publisher Copernicus GmbH Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1991959x (Issn) ISBN Medium
Area Expedition Conference
Notes Cited By :1; Export Date: 27 October 2019; Correspondence Address: Longo, M.; Harvard UniversityUnited States; email: mdplongo@gmail.com Approved no
Call Number EcoFoG @ webmaster @ Serial 890
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Author Salhi, L.; Nait-Rabah, O.; Deyrat, C.; Roos, C.
Title Numerical Modeling of Single Helical Pile Behavior under Compressive Loading in Sand Type Journal Article
Year 2013 Publication Electronic Journal of Geotechnical Engineering Abbreviated Journal Electron. J. Geotech. Eng.
Volume 18 Issue Bundle T Pages (down) 4119-4338
Keywords helical pile; finite element method; failure mechanisms; sand
Abstract The present research deals with helical piles behavior in cohesionless soil through finite element modeling. An approach of modeling of the screw-pile geometry has been proposed through the Finite Element Analysis (FEA) computer program Plaxis. The numerical results are compared with measurements from large scale test and the bearing capacity has been estimated using both cylindrical and individual bearing model. Moreover, different failure criterions have been applied to estimate the ultimate capacity. The effect of spacing ratio (S/Dh) on the screw-pile behavior has been further studied. It has found that results from the model fit the field results. Through the study of the load transfer mechanism, the transition from cylindrical shear to individual plate behavior occurs at a value of spacing ratio (1.5 to 2).
Address Laboratoire des matériaux et molécules en milieu amazonien, EcoFoG-Université des Antilles-Guyane, 97351 Cayenne, French Guiana
Corporate Author Thesis
Publisher Place of Publication Editor
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ISSN ISBN Medium
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Notes Approved no
Call Number EcoFoG @ webmaster @ Serial 525
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Author Lambs, L.; Bompy, F.; Imbert, D.; Corenblit, D.; Dulormne, M.
Title Seawater and freshwater circulations through coastal forested wetlands on a Caribbean Island Type Journal Article
Year 2015 Publication Water Abbreviated Journal Water
Volume 7 Issue 8 Pages (down) 4108-4128
Keywords 18O/2H stable isotope; Hydrology; Mangrove; Salinity; Swamp forest; Water level
Abstract Structure and composition of coastal forested wetlands are mainly controlled by local topography and soil salinity. Hydrology plays a major role in relation with tides, seaward, and freshwater inputs, landward. We report here the results of a two-year study undertaken in a coastal plain of the Guadeloupe archipelago (FWI). As elsewhere in the Caribbean islands, the study area is characterized by a micro-tidal regime and a highly seasonal climate. This work aimed at understanding groundwater dynamics and origin (seawater/freshwater) both at ecosystems and stand levels. These hydrological processes were assessed through 18O/16O and 2H/1H isotopic analyses, and from monthly monitoring of water level and soil salinity at five study sites located in mangrove (3) and swamp forest (2). Our results highlight the importance of freshwater budget imbalance during low rainfall periods. Sustained and/or delayed dry seasons cause soil salinity to rise at the mangrove/swamp forest ecotone. As current models on climate change project decreasing rainfall amounts over the inner Caribbean region, one may expect for this area an inland progression of the mangrove forest to the expense of the nearby swamp forest. © 2015 by the authors.
Address Geolab, UMR 6042, CNRS-Université Blaise Pascal, 4 rue Ledru, Clermont-Ferrand Cedex, France
Corporate Author Thesis
Publisher Place of Publication Editor
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Notes Export Date: 8 September 2015 Approved no
Call Number EcoFoG @ webmaster @ Serial 621
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Author Faustin, M.; Lebrini, M.; Robert, F.; Roos, C.
Title Corrosion studies of C38 steel by alkaloids extract of a tropical plant type Type Journal Article
Year 2011 Publication International Journal of Electrochemical Science Abbreviated Journal Int.J.Electrochem.Sci.
Volume 6 Issue 9 Pages (down) 4095-4113
Keywords Acidic media; C38 steel; Corrosion inhibitor; Plant extract
Abstract Alkaloids extract of Aspidosperma album was tested as corrosion inhibitor for C38 steel in 1 M HCl by using polarization and electrochemical impedance spectroscopy (EIS). Potentiodynamic polarization curves indicated that the plant extract behaves as mixed-type inhibitors. Impedance measurements showed that the double-layer capacitance decreased and charge-transfer resistance increased with increase in the inhibitors concentration and hence increasing in inhibition efficiency. The effect of temperature on the corrosion behavior of C38 steel in 1 M HCl with and without addition of plant extract was studied in the temperature range 25 – 55°C. The adsorption of the inhibitor molecules was in accordance with the Langmuir adsorption isotherm. The results obtained show that this plant extract could serve as an effective inhibitor for the corrosion of C38 steel in hydrochloric acid. © 2011 by ESG.
Address Laboratoire Matériaux et Molécules en Milieu Amazonien, UAG-UMR ECOFOG, Campus Trou Biran, Cayenne 97337, French Guiana
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 14523981 (Issn) ISBN Medium
Area Expedition Conference
Notes Export Date: 21 October 2011; Source: Scopus; Language of Original Document: English; Correspondence Address: Roos, C.; Laboratoire Matériaux et Molécules en Milieu Amazonien, UAG-UMR ECOFOG, Campus Trou Biran, Cayenne 97337, French Guiana; email: florent.robert@guyane.univ-ag.fr Approved no
Call Number EcoFoG @ webmaster @ Serial 348
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Author Christensen-Dalsgaard, K.K.; Ennos, A.R.; Fournier, M.
Title Changes in hydraulic conductivity, mechanical properties, and density reflecting the fall in strain along the lateral roots of two species of tropical trees Type Journal Article
Year 2007 Publication Journal of Experimental Botany Abbreviated Journal J. Exp. Bot.
Volume 58 Issue 15-16 Pages (down) 4095-4105
Keywords Buttress roots; Density; Hydraulic conductivity; Hydraulic-mechanical trade-offs; Modulus of elasticity; Tropical trees; Wood; Elastic moduli; Hydraulic conductivity; Wood; Buttress roots; Hydraulic-mechanical trade-offs; Tropical trees; Forestry; water; article; biomechanics; histology; legume; physiology; plant root; plant stem; tree; wood; Xylopia; Biomechanics; Fabaceae; Plant Roots; Plant Stems; Trees; Water; Wood; Xylopia; Conductivity; Elastic Strength; Forestry; Wood
Abstract Roots have been described as having larger vessels and so greater hydraulic efficiency than the stem. Differences in the strength and stiffness of the tissue within the root system itself are thought to be an adaptation to the loading conditions experienced by the roots and to be related to differences in density. It is not known how potential mechanical adaptations may affect the hydraulic properties of the roots. The change in strength, stiffness, conductivity, density, sapwood area, and second moment of area distally along the lateral roots of two tropical tree species in which the strain is known to decrease rapidly was studied and the values were compared with those of the trunk. It was found that as the strain fell distally along the roots, so did the strength and stiffness of the tissue, whereas the conductivity increased exponentially. These changes appeared to be related to differences in density. In contrast to the distal-most roots, the tissue of the proximal roots had a lower conductivity and higher strength than that of the trunk. This suggests that mechanical requirements on the structure rather than the water potential gradient from roots to branches are responsible for the general pattern that roots have larger vessels than the stem. In spite of their increased transectional area, the buttressed proximal roots were subjected to higher levels of stress and had a lower total conductivity than the rest of the root system. © 2007 The Author(s).
Address AgroParisTech, LERFOB, Ecole Nationale du Genie Rural, des Eaux et Forêts, 14 Avenue Girardet-CS 4216, 54000 Nancy Cedex, France
Corporate Author Thesis
Publisher Place of Publication Editor
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Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 00220957 (Issn) ISBN Medium
Area Expedition Conference
Notes Cited By (since 1996): 6; Export Date: 22 October 2011; Source: Scopus; Coden: Jeboa; doi: 10.1093/jxb/erm268; PubMed ID: 18039738; Language of Original Document: English; Correspondence Address: Christensen-Dalsgaard, K.K.; University of Manchester, Faculty of Life Sciences, Jackson's Mill, Manchester M60 1QD, United Kingdom; email: karen@cd-mail.dk; Chemicals/CAS: water, 7732-18-5; Water, 7732-18-5 Approved no
Call Number EcoFoG @ webmaster @ Serial 353
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Author Coste, S.; Roggy, J.C.; Schimann, H.; Epron, D.; Dreyer, E.
Title A cost-benefit analysis of acclimation to low irradiance in tropical rainforest tree seedlings: leaf life span and payback time for leaf deployment Type Journal Article
Year 2011 Publication Journal of Experimental Botany Abbreviated Journal J. Exp. Bot.
Volume 62 Issue 11 Pages (down) 3941-3955
Keywords Carbon balance; construction cost; functional diversity; leaf life span; payback time; photosynthesis; tropical rainforest
Abstract The maintenance in the long run of a positive carbon balance under very low irradiance is a prerequisite for survival of tree seedlings below the canopy or in small gaps in a tropical rainforest. To provide a quantitative basis for this assumption, experiments were carried out to determine whether construction cost (CC) and payback time for leaves and support structures, as well as leaf life span (i) differ among species and (ii) display an irradiance-elicited plasticity. Experiments were also conducted to determine whether leaf life span correlates to CC and payback time and is close to the optimal longevity derived from an optimization model. Saplings from 13 tropical tree species were grown under three levels of irradiance. Specific-CC was computed, as well as CC scaled to leaf area at the metamer level. Photosynthesis was recorded over the leaf life span. Payback time was derived from CC and a simple photosynthesis model. Specific-CC displayed only little interspecific variability and irradiance-elicited plasticity, in contrast to CC scaled to leaf area. Leaf life span ranged from 4 months to > 26 months among species, and was longest in seedlings grown under lowest irradiance. It was always much longer than payback time, even under the lowest irradiance. Leaves were shed when their photosynthesis had reached very low values, in contrast to what was predicted by an optimality model. The species ranking for the different traits was stable across irradiance treatments. The two pioneer species always displayed the smallest CC, leaf life span, and payback time. All species displayed a similar large irradiance-elicited plasticity.
Address [Coste, S; Epron, D; Dreyer, E] INRA, UMR1137, Ctr INRA Nancy, F-54280 Champenoux, France, Email: dreyer@nancy.inra.fr
Corporate Author Thesis
Publisher Oxford Univ Press Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-0957 ISBN Medium
Area Expedition Conference
Notes WOS:000292838700021 Approved no
Call Number EcoFoG @ webmaster @ Serial 331
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Author Aubry-Kientz, Mélaine ; Laybros, Anthony ; Weinstein, Ben ; Ball, James G. C. ; Jackson, Toby ; Coomes, David ; Vincent, Grégoire
Title Multisensor data fusion for improved segmentation of individual tree crowns in dense tropical forests Type Journal Article
Year 2021 Publication IEEE Journal of Selected topics in Applied Earth Observations and Remote Sensing Abbreviated Journal
Volume 14 Issue Pages (down) 3927-3936
Keywords
Abstract Automatic tree crown segmentation from remote sensing data is especially challenging in dense, diverse, and multilayered tropical forest canopies, and tracking mortality by this approach is even more difficult. Here, we examine the potential for combining airborne laser scanning (ALS) with multispectral and hyperspectral data to improve the accuracy of tree crown segmentation at a study site in French Guiana. We combined an ALS point cloud clustering method with a spectral deep learning model to achieve 83% accuracy at recognizing manually segmented reference crowns (with congruence >0.5). This method outperformed a two-step process that involved clustering the ALS point cloud and then using the logistic regression of hyperspectral distances to correct oversegmentation. We used this approach to map tree mortality from repeat surveys and show that the number of crowns identified in the first that intersected with height loss clusters was a good estimator of the number of dead trees in these areas. Our results demonstrate that multisensor data fusion improves the automatic segmentation of individual tree crowns and presents a promising avenue to study forest demography with repeated remote sensing acquisitions.
Address
Corporate Author Thesis
Publisher IEEE Place of Publication Editor
Language Summary Language Original Title
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Notes Approved no
Call Number EcoFoG @ webmaster @ Serial 1008
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