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Li, M. C., Royer, M., Stien, D., Lecante, A., & Roos, C. (2008). Inhibitive effect of sodium eperuate on zinc corrosion in alkaline solutions. Corrosion Sci., 50(7), 1975–1981.
Abstract: The effect of sodium eperuate prepared from Wallaba (Eperua falcata Aubl) extract on zinc corrosion was investigated in alkaline solutions with chloride ions (i.e., simulated concrete pore solutions) by using electrochemical techniques. Sodium eperuate inhibits the corrosion of zinc in 0.1 M NaCl solutions with pH 9.6. As its concentration increases to 1 g/L, the inhibition efficiency reaches approximately 92%. In alkaline solutions with pH 12.6, sodium eperuate has no adverse effect on passivity of zinc, and retards the chloride attack. These suggest that sodium eperuate is an effective inhibitor for the protection of zinc in alkaline environments. (c) 2008 Elsevier Ltd. All rights reserved.
Keywords: zinc; concrete; EIS; alkaline corrosion; passivity
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Lecante, A., Robert, F., Lebrini, M., & Roos, C. (2011). Inhibitive Effect of Siparuna Guianensis Extracts on the Corrosion of Low Carbon Steel in Acidic Media. Int.J.Electrochem.Sci., 6(11), 5249–5264.
Abstract: The present study examines the effect of alkaloids extract from Siparuna guianensis leaves and stems on corrosion of C38 steel in 0.1 M HCl using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization technique and Raman spectroscopy. The protection efficiency is better with stems alkaloids extract. The inhibition was assumed to occur via adsorption of inhibitor molecules on the metal surface. The influence of stems alkaloids extract concentration on corrosion of low carbon steel in 0.1 M HCl was studied. The inhibition efficiency obtained from impedance and polarization measurements was in a good agreement and was found to increase with increasing concentration of alkaloids extract up to 50 mg/L for stems extract. The adsorption of the extract on the low carbon steel surface obeys the Langmuir adsorption.
Keywords: Alkaloids extract; corrosion inhibition; C38 steel; EIS; raman spectroscopy
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Lebrini, M., Robert, F., & Roos, C. (2010). Inhibition Effect of Alkaloids Extract from Annona Squamosa Plant on the Corrosion of C38 Steel in Normal Hydrochloric Acid Medium. Int. J. Electrochem. Sci., 5(11), 1698–1712.
Abstract: In this work, an alkaloids extract from Annona squamosa plant have been studied as possible corrosion inhibitor for C38 steel in molar hydrochloric acid (1 M HCl). Potentiodynamic polarization and AC impedance methods have been used. The corrosion inhibition efficiency increases on increasing plant extract concentration. Polarisation studies showed that Annona squamosa extract was mixed-type inhibitor in 1 M HCl. The inhibition efficiency of Annona squamosa extract was temperature-dependent and its addition led to an increase of the activation corrosion energy revealing a physical adsorption between the extract and the metal surface. The adsorption of the Annona squamosa extract followed Langmuir's adsorption isotherm. The inhibitive effect of Annona squamosa is ascribed to the presence of organic compounds in the extract. The examined extract is considered as non-cytotoxic substance.
Keywords: Plant extract; corrosion inhibitors; C38 steel; acidic media; adsorption
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Dejean, A., Corbara, B., Leroy, C., Delabie, J. H. C., Rossi, V., & Cereghino, R. (2011). Inherited Biotic Protection in a Neotropical Pioneer Plant. PLoS One, 6(3), e18071.
Abstract: Chelonanthus alatus is a bat-pollinated, pioneer Gentianaceae that clusters in patches where still-standing, dried-out stems are interspersed among live individuals. Flowers bear circum-floral nectaries (CFNs) that are attractive to ants, and seed dispersal is both barochorous and anemochorous. Although, in this study, live individuals never sheltered ant colonies, dried-out hollow stems – that can remain standing for 2 years – did. Workers from species nesting in dried-out stems as well as from ground-nesting species exploited the CFNs of live C. alatus individuals in the same patches during the daytime, but were absent at night (when bat pollination occurs) on 60.5% of the plants. By visiting the CFNs, the ants indirectly protect the flowers – but not the plant foliage – from herbivorous insects. We show that this protection is provided mostly by species nesting in dried-out stems, predominantly Pseudomyrmex gracilis. That dried-out stems remain standing for years and are regularly replaced results in an opportunistic, but stable association where colonies are sheltered by one generation of dead C. alatus while the live individuals nearby, belonging to the next generation, provide them with nectar; in turn, the ants protect their flowers from herbivores. We suggest that the investment in wood by C. alatus individuals permitting still-standing, dried-out stems to shelter ant colonies constitutes an extended phenotype because foraging workers protect the flowers of live individuals in the same patch. Also, through this process these dried-out stems indirectly favor the reproduction (and so the fitness) of the next generation including both their own offspring and that of their siblings, all adding up to a potential case of inclusive fitness in plants.
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Yazdani, R., Scotti, I., Jansson, G., Plomion, C., & Mathur, G. (2003). Inheritance and diversity of simple sequence repeat (SSR) microsatellite markers in various families of Picea abies. Hereditas, 138(3), 219–227.
Abstract: A large number of sequence-specific SSRs were screened by using electrophoresis on metaphore agarose gels with the bands visualized by ethidium bromide staining. Many SSRs appeared as codominant and many as dominant markers, with presence or absence of bands. A simple Mendelian inheritance pattern for most codominant and dominant SSR loci was found. For many codominant SSR markers, null alleles were detected. The proportion of dominant microsatellites detected in this study (close to 50 %) was much higher than that commonly reported in many other studies. A high proportion of dominant markers together with a high frequency of codominant markers with null alleles may represent two important limitations for the use of microsatellites in different studies. On the other hand, many polymorphic codominant SSR microsatellite markers were found to be highly repeatable, and can be used for population studies, seed certification, quality control of controlled crosses, paternity analysis, pollen contamination, and mapping of QTL in related families. In this paper, we report on the inheritance pattern and diversity of codominant and dominant SSR microsatellites in seven families of Picea abies sharing a common mother.
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Stahl, C., Burban, B., Wagner, F., Goret, J. - Y., Bompy, F., & Bonal, D. (2013). Influence of Seasonal Variations in Soil Water Availability on Gas Exchange of Tropical Canopy Trees. Biotropica, 45(2), 155–164.
Abstract: Seasonal variations in environmental conditions influence the functioning of the whole ecosystem of tropical rain forests, but as yet little is known about how such variations directly influence the leaf gas exchange and transpiration of individual canopy tree species. We examined the influence of seasonal variations in relative extractable water in the upper soil layers on predawn leaf water potential, saturated net photosynthesis, leaf dark respiration, stomatal conductance, and tree transpiration of 13 tropical rain forest canopy trees (eight species) over 2 yr in French Guiana. The canopies were accessed by climbing ropes attached to the trees and to a tower. Our results indicate that a small proportion of the studied trees were unaffected by soil water depletion during seasonal dry periods, probably thanks to efficient deep root systems. The trees showing decreased tree water status (i.e., predawn leaf water potential) displayed a wide range of leaf gas exchange responses. Some trees strongly regulated photosynthesis and transpiration when relative extractable water decreased drastically. In contrast, other trees showed little variation, thus indicating good adaptation to soil drought conditions. These results have important applications to modeling approaches: indeed, precise evaluation and grouping of these response patterns are required before any tree-based functional models can efficiently describe the response of tropical rain forest ecosystems to future changes in environmental conditions. © 2012 by The Association for Tropical Biology and Conservation.
Keywords: French Guiana; Photosynthesis; Predawn leaf water potential; Rain forest; Relative extractable water; Respiration; Soil drought; Transpiration
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Sprenger, P. P., Hartke, J., Feldmeyer, B., Orivel, J., Schmitt, T., & Menzel, F. (2019). Influence of Mutualistic Lifestyle, Mutualistic Partner, and Climate on Cuticular Hydrocarbon Profiles in Parabiotic Ants. J Chem Ecol, 45(9), 741–754.
Abstract: A vital trait in insects is their cuticular hydrocarbon (CHC) profile, which protects the insect against desiccation and serves in chemical communication. Due to these functions, CHC profiles are shaped by both climatic conditions and biotic interactions. Here, we investigated CHC differentiation in the neotropical parabiotic ant species Crematogaster levior and Camponotus femoratus, which mutualistically share a nest. Both consist of two cryptic species each (Cr. levior A and B and Ca. femoratus PAT and PS) that differ genetically and possess strongly different CHC profiles. We characterized and compared CHC profiles of the four cryptic species in detail. Our results suggest that Cr. levior A, Ca. femoratus PAT and Ca. femoratus PS adapted their CHC profiles to the parabiotic lifestyle by producing longer-chain CHCs. At the same time, they changed their major CHC classes, and produce more alkadienes and methyl-branched alkenes compared to Cr. levior B or non-parabiotic species. The CHC profiles of Cr. levior B were more similar to related, non-parabiotic species of the Orthocrema clade than Cr. levior A, and the chain lengths of B were similar to the reconstructed ancestral state. Signals of both the parabiotic partner (biotic conditions) and climate (abiotic conditions) were found in the CHC profiles of all four cryptic species. Our data suggest that mutualisms shaped the CHC profiles of the studied species, in particular chain length and CHC class composition. Beside this, signals of the parabiotic partners indicate potential impacts of biotic interactions, via chemical mimicry or chemical camouflage.
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Bardet, S., Beauchene, J., & Thibaut, B. (2003). Influence of basic density and temperature on mechanical properties perpendicular to grain of ten wood tropical species. Ann. For. Sci., 60(1), 49–59.
Abstract: The influence of temperature on transverse mechanical properties of 10 tropical species in green condition was studied in radial compression (0 to 99 degreesC), transverse shear with longitudinal-radial shearing plane and rupture of the longitudinal-tangential plane (20 to 80 degreesC). Basic density ranged from 0.21 to 0.91 g cm(-3). Load-displacement curves were characterised by initial rigidity, yield stress, yield strain and strain energy at 20% strain level. The relation between each criterion and basic density was expressed by a power law. The dependency on temperature evidenced a sharp glassy transition, except for the fracture energy only slightly influenced by temperature. An empirical model allowed evaluating a transition temperature between 51 and 69 degreesC, depending on the species and the criterion, which was attributed to lignin. Detailed analysis of the apparent modulus in radial compression suggested that complex relaxation phenomena occur around 10 degreesC and that the rubbery state is not fully reached at 80 degreesC.
Keywords: green wood; tropical wood; transverse mechanical properties; basic density; softening temperature
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Grangier, J., Dejean, A., Male, P. J. G., & Orivel, J. (2008). Indirect defense in a highly specific ant-plant mutualism. Naturwissenschaften, 95(10), 909–916.
Abstract: Although associations between myrmecophytes and their plant ants are recognized as a particularly effective form of protective mutualism, their functioning remains incompletely understood. This field study examined the ant-plant Hirtella physophora and its obligate ant associate Allomerus decemarticulatus. We formulated two hypotheses on the highly specific nature of this association: (1) Ant presence should be correlated with a marked reduction in the amount of herbivory on the plant foliage; (2) ant activity should be consistent with the “optimal defense” theory predicting that the most vulnerable and valuable parts of the plant are the best defended. We validated the first hypothesis by demonstrating that for ant-excluded plants, expanding leaves, but also newly matured ones in the long term, suffered significantly more herbivore damage than ant-inhabited plants. We showed that A. decemarticulatus workers represent both constitutive and inducible defenses for their host, by patrolling its foliage and rapidly recruiting nestmates to foliar wounds. On examining how these activities change according to the leaves' developmental stage, we found that the number of patrolling ants dramatically decreased as the leaves matured, while leaf wounds induced ant recruitment regardless of the leaf's age. The resulting level of these indirect defenses was roughly proportional to leaf vulnerability and value during its development, thus validating our second hypothesis predicting optimal protection. This led us to discuss the factors influencing ant activity on the plant's surface. Our study emphasizes the importance of studying both the constitutive and inducible components of indirect defense when evaluating its efficacy and optimality.
Keywords: Allomerus decemarticulatus; Hirtella physophora; indirect defense; myrmecophytes; optimal defense theory
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Martos, F., Dulormne, M., Pailler, T., Bonfante, P., Faccio, A., Fournel, J., et al. (2009). Independent recruitment of saprotrophic fungi as mycorrhizal partners by tropical achlorophyllous orchids. New Phytologist, 184(3), 668–681.
Abstract: Mycoheterotrophic orchids have adapted to shaded forest understory by shifting to achlorophylly and receiving carbon from their mycorrhizal fungi. In temperate forests, they associate in a highly specific way with fungi forming ectomycorrhizas on nearby trees, and exploiting tree photosynthates. However, many rainforests lack ectomycorrhizal fungi, and there is evidence that some tropical Asiatic species associate with saprotrophic fungi. To investigate this in different geographic and phylogenetic contexts, we identified the mycorrhizal fungi supporting two tropical mycoheterotrophic orchids from Mascarene (Indian Ocean) and Caribbean islands. We tested their possible carbon sources by measuring natural nitrogen (15N) and carbon (13C) abundances. Saprotrophic basidiomycetes were found: Gastrodia similis associates with a wood-decaying Resinicium (Hymenochaetales); Wullschlaegelia aphylla associates with both litter-decaying Gymnopus and Mycena species, whose rhizomorphs link orchid roots to leaf litter. The 15N and 13C abundances make plausible food chains from dead wood to G. similis and from dead leaves to W. aphylla. We propose that temperature and moisture in rainforests, but not in most temperate forests, may favour sufficient saprotrophic activity to support development of mycoheterotrophs. By enlarging the spectrum of mycorrhizal fungi and the level of specificity in mycoheterotrophic orchids, this study provides new insights on orchid and mycorrhizal biology in the tropics. © 2009 New Phytologist.
Keywords: Mycoheterotrophy; Mycorrhizas; Orchids; Rainforests; Saprotrophic fungi; Stable isotopes
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