290 research outputs found
SECM study of steel corrosion under scratched microencapsulated epoxy resin
No full textScratch tests were performed on epoxy coated steel samples with and without microcapsulated linseed oil, known to develop a polymerized protective layer after having been released from the capsules at the damaged sites. The scanning electrochemical microscope has been applied to monitor the protection efficiency of this self-healing coating in aqueous acidic solution. In the proximity of the local damage, both the anodic metal dissolution and the cathodic oxygen reduction showed that the coating with microcapsules substantially and spontaneously decreased the rate of corrosion proving the self-repair concept of the coating. Electrochemical impedance measurements underline the protective effect of the coating as well
Global variability in leaf respiration in relation to climate and leaf traits
No full textOwen K. Atkin team : Owen K. Atkin, Keith J. Bloomfield, Peter B. Reich, Mark G. Tjoelker, Gregory P. Asner, Damien Bonal, Gerhard Bönisch, Matt Bradford, Lucas A. Cernusak, Eric G. Cosio, Danielle Creek, Kristine Y. Crous, Tomas Domingues, Jeffery S. Dukes, John J. G. Egerton, John R. Evans, Graham D. Farquhar, Nikolaos M. Fyllas, Paul P.G. Gauthier, Emanuel Gloor, Teresa E. Gimeno, Kevin L. Griffin, Rossella Guerrieri, Mary A. Heske, Chris Huntingford, Françoise Yoko Ishida, Jens Kattge, Hans Lambers, Michael J. Liddell, Christopher H. Lusk, Roberta E. Martin, Ayal P. Maksimov, Trofim C. Maximov, Yadvinder Mahl, Belinda E. Medlyn, Patrick Meir, Lina M. Mercado, Nicholas Mirotchnick, Desmond Ng, Ülo Niinemets, Odhran S. O’Sullivan, Oliver L. Philips1, Lourens Poorter, Pieter Poot, I. Colin Prentice, Norma Salinas, Lucy M. Rowland, Mike G. Ryan, Stephen Sitch, Martijn Slot, Nicholas G. Smith, Matthew H. Turnbull, Mark C. VanderWel, Fernando Valladares, Eric J. Veneklaas, Lasantha K. Weerasinghe, Christian Wirth, Ian J. Wright, Kirk Wythers, Jen Xiang, Shuang Xiang and Joana Zaragoza-Castellsabsen
Global variability in leaf respiration in relation to climate and leaf traits
No full textOwen K. Atkin team : Owen K. Atkin, Keith J. Bloomfield, Peter B. Reich, Mark G. Tjoelker, Gregory P. Asner, Damien Bonal, Gerhard Bönisch, Matt Bradford, Lucas A. Cernusak, Eric G. Cosio, Danielle Creek, Kristine Y. Crous, Tomas Domingues, Jeffery S. Dukes, John J. G. Egerton, John R. Evans, Graham D. Farquhar, Nikolaos M. Fyllas, Paul P.G. Gauthier, Emanuel Gloor, Teresa E. Gimeno, Kevin L. Griffin, Rossella Guerrieri, Mary A. Heske, Chris Huntingford, Françoise Yoko Ishida, Jens Kattge, Hans Lambers, Michael J. Liddell, Christopher H. Lusk, Roberta E. Martin, Ayal P. Maksimov, Trofim C. Maximov, Yadvinder Mahl, Belinda E. Medlyn, Patrick Meir, Lina M. Mercado, Nicholas Mirotchnick, Desmond Ng, Ülo Niinemets, Odhran S. O’Sullivan, Oliver L. Philips1, Lourens Poorter, Pieter Poot, I. Colin Prentice, Norma Salinas, Lucy M. Rowland, Mike G. Ryan, Stephen Sitch, Martijn Slot, Nicholas G. Smith, Matthew H. Turnbull, Mark C. VanderWel, Fernando Valladares, Eric J. Veneklaas, Lasantha K. Weerasinghe, Christian Wirth, Ian J. Wright, Kirk Wythers, Jen Xiang, Shuang Xiang and Joana Zaragoza-Castellsabsen
Dew-induced transpiration suppression impacts the water and isotope balances of <i>Colocasia</i> leaves
No full textAbstractFoliar uptake of water from the surface of leaves is common when rainfall is scarce and non-meteoric water such as dew or fog is more abundant. However, many species in more mesic environments have hydrophobic leaves that do not allow the plant to uptake water. Unlike foliar uptake, all species can benefit from dew- or fog-induced transpiration suppression, but despite its ubiquity, transpiration suppression has so far never been quantified. Here, we investigate the effect of dew-induced transpiration suppression on the water balance and the isotope composition of leaves via a series of experiments. Characteristically hydrophobic leaves of a tropical plant, Colocasia esculenta, are misted with isotopically enriched water to reproduce dew deposition. This species does not uptake water from the surface of its leaves. We measure leaf water isotopes and water potential and find that misted leaves exhibit a higher water potential (p < 0.05) and a more depleted water isotope composition than dry leaves (p < 0.001), suggesting a ~30% decrease in transpiration rate (p < 0.001) compared to control leaves. We propose three possible mechanisms governing the interaction of water droplets with leaf energy balance: increase in albedo from the presence of dew droplets, decrease in leaf temperature from the evaporation of dew, and local decrease in vapor pressure deficit. Comparing previous studies on foliar uptake to our results, we conclude that transpiration suppression has an effect of similar amplitude, yet opposite sign to foliar uptake on leaf water isotopes.</jats:p
Author Correction: Disruption of mitochondrial complex I induces progressive parkinsonism
No full textIn the version of this article initially published, the two bottom-left panels in Extended Data Fig. 8b duplicated the top-left and bottom-right panels of Fig. 4d presenting open field traces in mice. The panels have now been replaced with new images. The errors have been corrected in the online version of the article.Loss of functional mitochondrial complex I (MCI) in the dopaminergic neurons of the substantia nigra is a hallmark of Parkinson’s disease1. Yet, whether this change contributes to Parkinson’s disease pathogenesis is unclear2. Here we used intersectional genetics to disrupt the function of MCI in mouse dopaminergic neurons. Disruption of MCI induced a Warburg-like shift in metabolism that enabled neuronal survival, but triggered a progressive loss of the dopaminergic phenotype that was first evident in nigrostriatal axons. This axonal deficit was accompanied by motor learning and fine motor deficits, but not by clear levodopa-responsive parkinsonism—which emerged only after the later loss of dopamine release in the substantia nigra. Thus, MCI dysfunction alone is sufficient to cause progressive, human-like parkinsonism in which the loss of nigral dopamine release makes a critical contribution to motor dysfunction, contrary to the current Parkinson’s disease paradigm.Electron microscopy tissue processing and imaging was performed at the Northwestern University Center for Advanced Microscopy, supported by NCI CCSG P30 CA060553 awarded to the Robert H. Lurie Comprehensive Cancer Center. This study was supported by grants from the Michael J. Fox Foundation (to D.J.S.), the JPB Foundation (to D.J.S.), the IDP Foundation (to D.J.S.), the Flanagan Fellowship (to P.G.-R.) and the European Research Council ERC Advanced Grant PRJ201502629 (to J.L.-B.).Peer reviewe
Ocean acidification impacts primary and bacterial production in Antarctic coastal waters during austral summer
No full textProgress Code: completedThree experiments were performed at Davis Station, East Antarctica, 77 degrees 58' E, 68 degrees 35' S to determine the effects of ocean acidification on natural assemblages of Antarctica marine microbes (bacteria, viruses, phytoplankton and protozoa). Incubation tanks (6 * 650 L minicosms) were filled on the 30/12/08, 20/01/09 and 09/02/09 with sea water that was filtered through 200 microns mesh to remove metazoan grazers. The pH of each tank was adjusted by adding calculated amounts of CO2 saturated sea water. Treatment concentrations were maintained daily and microbial communities incubated for up to 12 days. The three experiments spanned early-, mid- and late-summer, with CO2 treatments ranging from pre-industrial to post-2100.<br/><br/>The Excel spreadsheet contains 3 tabs:<br/>Experiment 1 - Early Summer<br/>Experiment 2 - Mid Summer<br/>Experiment 3 - Late Summer<br/><br/>Within each tab there are measurements for:<br/>pCO2, dissolved inorganic carbon, Pmax, alpha, Ek, chl a, gross primary production (14C), bacterial production (14C), cell-specific bacterial productivity, bacterial abundance, dissolved organic carbon, particulate organic carbon, heterotrophic nanoflagellates, nitrate+nitrite, phosphate, silicate, ammonium, net community production, respiration, gross primary production (O2), photosynthesis:respiration ratios. Units for each measurement supplied within.<br/><br/>Please see the following paper for interpretation of this data:<br/>Westwood, K.J., Thomson, P.G., van den Enden, R., Maher, L., Wright, S.W., Davidson, A.T. (2018). Ocean acidification impacts primary and bacterial production in Antarctic coastal waters during austral summer. Journal of Experimental Marine Biology and Ecology 498: 46-60, doi: 10.1016/j.jembe.2017.11.003
Agroecological aspects of evaluating agricultural research and development:
No full textIn this paper we describe how biophysical data can be used, in conjunction with agroecological concepts and multimarket economic models, to systematically evaluate the effects of agricultural R&D in ways that inform research priority setting and resource allocation decisions. Agroecological zones can be devised to help estimate the varying, site-specific responses to new agricultural technologies and to evaluate the potential for research to spill over from one agroecological zone to another. The application of agroecological zonation procedures in an international agricultural research context is given special attention.Agricultural research., Technological innovations., Agricultural economics and policies.,
ULTRAFAST TRANSIENT SOLVATION OF POLAR DYE MOLECULES IN SIMPLE POLAR SOLVENTS
No full text M.A. Kahlow. T.J. Kang and P.F. Barbara. J. Chem. Phys. 88. 2372 (1988); M.A. Kahlow. W. Jarzeba. T.P. DuBruil and P.F. Barbara. Rev. Sci. Instrum. (in press). E.W. Castner. G.R. Fleming and B. Bagchi. Chem. Phys. Lett. (in press). P.G. Wolynes. J. Chem. Phys. 86. 5133 (1987).Author Institution: Department of Chemistry, University of Minnesota,Recently we constructed a time resolved fluorescence apparatus with a resolution of less than 300 femtoseconds1. We have used this instrument to measure the microscopic solvation dynamics of three simple polar solvents (propylene carbonate, propiontrile, and methanol) by observing the time resolved fluorescence from coumarin 152. The solvation rates are non-singly exponential, with components both shorter and longer than the longitudinal relaxation times r1 of the solvents. Results will be discussed in terms of several recent theoretical
Urban megaprojects and water justice in Southeast Asia: Between global economies and community transitions
No full textWithin the Southeast Asian context, urban megaprojects are often delivered in aquatic or semi-aquatic contexts, transforming local hydrological systems used for sanitation, agriculture, sustenance, resource use and cultural purposes by the local populations. This paper addresses a key knowledge gap on the impacts of urban megaprojects on water security and water-related human rights in Southeast Asia through a literature review, field observations and digital earth observation. Three case studies in Cambodia, Vietnam and Myanmar were used to develop a picture of urban megaproject impacts on urban water landscapes and the human rights of local communities. The paper adapts recent human rights frameworks developed specifically for megaproject life cycles and applies them to the selected urban megaproject case studies. The seven stages in the megaproject life cycle are linked with specific accountability measures for duty bearers. Current challenges and opportunities for the global urban development community are developed in relation to water justice and megaprojects. Further the question of a just urban transition is developed to mediate between megaproject proponents and local communities in the Global South
Leaf Carbon Export and Nonstructural Carbohydrates in Relation to Diurnal Water Dynamics in Mature Oak Trees
No full textTrees typically experience large diurnal depressions in water potential, which may impede carbon export from leaves during the day because the xylem is the source of water for the phloem. As water potential becomes more negative, higher phloem osmotic concentrations are needed to draw water in from the xylem. Generating this high concentration of sugar in the phloem is particularly an issue for the ∼50% of trees that exhibit passive loading. These ideas motivate the hypothesis that carbon export in woody plants occurs predominantly at night, with sugars that accumulate during the day assisting in mesophyll turgor maintenance or being converted to starch. To test this, diurnal and seasonal patterns of leaf nonstructural carbohydrates, photosynthesis, solute, and water potential were measured, and carbon export was estimated in leaves of five mature (\u3e20 m tall) red oak (Quercus rubra) trees, a species characterized as a passive loader. Export occurred throughout the day at equal or higher rates than at night despite a decrease in water potential to −1.8 MPa at midday. Suc and starch accumulated over the course of the day, with Suc contributing ∼50% of the 0.4 MPa diurnal osmotic adjustment. As a result of this diurnal osmotic adjustment, estimates of midday turgor were always \u3e0.7 MPa. These findings illustrate the robustness of phloem functioning despite diurnal fluctuations in leaf water potential and the role of nonstructural carbohydrates in leaf turgor maintenance
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