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Ionic Species Affect the Self-Propulsion of Urease-Powered Micromotors

research 2020年第1期2020卷 349-362页

作者： xavier Arque xavier andres.rafael mes.re Bernard Ciraulo Jaime Ortega Arroyo Romain Quidant Tania Patino Samuel Sanchez Institute for Bioengineering of Catalonia(IBEC) The Barcelona Institute of Science and Technology(BIST)Baldiri i Reixac 10-1208028 BarcelonaSpain Institute of Photonic Sciences(ICFO) The Barcelona Institute of Science and TechnologyCarl Friedrich Gauss 308860 CastelldefelsBarcelonaSpain InstitucióCatalana de recerca i Estudis Avançats(ICreA) Pg.Lluís Companys 2308010 BarcelonaSpain Chemistry Department University of RomeTor VergataVia della Ricerca Scientifica00133 RomeItaly

Enzyme-powered motors self-propel through the catalysis of in situ bioavailable fuels,which makes them excellent candidates for biomedical ***,fundamental issues like their motion in biological fluids and the understanding of the propulsion mechanism are critical aspects to be tackled before a future application in ***,we investigated the physicochemical effects of ionic species on the self-propulsion of urease-powered *** showed that the presence of PBS,NaOH,NaCl,and HEPES reduced self-propulsion of urease-powered micromotors pointing towards iondependent mechanisms of *** studied the 3D motion of urease micromotors using digital holographic microscopy to rule out any motor-surface interaction as the cause of motion decay when salts are present in the *** order to protect and minimize the negative effect of ionic species on micromotors’performance,we coated the motors with methoxypolyethylene glycol amine(mPEG)showing higher speed compared to noncoated motors at intermediate ionic *** results provide new insights into the mechanism of urease-powered micromotors,study the effect of ionic media,and contribute with potential solutions to mitigate the reduction of mobility of enzyme-powered micromotors.

关键词： holographic salts catalysis

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Multiple ecological strategies explain the distribution of exotic and native C_(4) grasses in heterogeneous early successional sites in Hawai’i

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Journal of Plant Ecology 2017年第3期10卷 426-439页

作者： rafael de Oliveira xavier Carla M.D’Antonio Ecology and Conservation Lab Department of HydrobiologyFederal University of São CarlosWashington Luís Highwaykm 235São CarlosSão Paulo 13565-905Brazil Environmental Studies Program 4312-L Bren University of CaliforniaSanta BarbaraCA 93106USA

Aims Biotic homogenization results in novel communities contain-ing multiple exotic *** attributes that contribute to the dominance of invaders and increase invasibility of communities have been identified,but rarely have factors governing the domi-nance of co-occurring invaders been *** we assess the presence and performance of five exotic and one native C_(4) grass species across local(microsite)and more broad-scale variation in fire history,soil age,altitude and *** ask whether species show preferences for the same conditions,whether all are constrained by poor soil development,and how their performance changes when alone versus *** addition to providing information useful to managers who want to control some of these species,such information can help to predict how distributions might change with climate change Methods We measured percent cover and plant height of each grass species in 64 plots in each of 15 sites,located in young volcanic substrates across environmental gradients in Hawai’i Volcanoes National Park,Hawai’i,*** varied in fire history and soil age,across altitu-dinal and precipitation *** estimated microsite heteroge-neity by measuring rock cover and soil depth,where each species was present and in plots as a *** analyzed effects of pos-sible controlling variables using chi-square tests and Generalized Additive Mixed *** Findings Two species(Schizachyrium condensatum and Hyparrhenia rufa)were absent in shallow soil,restricted to more mesic sites and showed increasing performance with soil *** contrast,two other species(Andropogon virginicus and Melinis repens)tended to occur in shal-low soil with high rock cover across a wide range of *** addi-tional species(Melinis minutiflora)was weakly affected by soil depth and was the dominant at higher elevation(more mesic)and on burned sites,especially in old *** species was largely absent from lower elevation si

关键词： elevation gradient fire invasive species Melinis minutiflora soil depth

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Selective and taxon-dependent effects of semi-feral cattle grazing on tree regeneration in an old-growth Mediterranean mountain forest

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Forest Ecosystems 2020年第1期7卷 128-140页

作者： xavier Fortuny Christopher Carcaillet Sandrine Chauchard Ecole Pratique des Hautes Etudes(EPHE) PSL University75014 ParisFrance Laboratoire d’ cologie des Hydrosystèmes Naturels et Anthropisés(UMR5023 CNRS UniversitéLyon 1ENTPE)69622 VilleurbanneFrance Universitéde Lorraine AgroParisTechINRAEUMR Silva54000 NancyFrance

Background:In Mediterranean mountain socio-ecosystems,both grazing by livestock and the dry season may influence tree ***,the relative contributions of these drivers are poorly known,even though present and future canopy composition might result from past and present variations in climate and herbivore *** study aims to test how semi-feral cattle presence and season affect tree ***:The study was conducted using permanent plots inside and outside a cattle exclosure in an old-growth Mediterranean *** and seedlings were counted five times per year(winter,early spring,middle spring,summer,fall)and monitored over 7 ***:Semi-feral cattle exclusion increased Acer,Fagus,Ilex,Pinus,Prunus and Quercus sapling densities and increased Acer,Fraxinus,Ilex,Quercus and Sorbus seedling ***,the dry season did not exert any noticeable effects on the sapling or seedling densities of any of the studied ***:Semi-feral cattle presence may limit tree regeneration through taxon-dependent effects,which suggests that the current decrease in grazing livestock across the Mediterranean basin will modify recruitment processes and,likely,future forest ***:Semi-feral cattle presence acts as a selective driver of tree community composition.

关键词： Cattle Climate Experiment Herbivory Forest pastoralism

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Fraying around the edges:negative effects of the invasive Tradescantia zebrina *** Bosse(Commelinaceae)on tree regeneration in the Atlantic Forest under different competitive and environmental conditions

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Journal of Plant Ecology 2019年第4期12卷 713-721页

作者： Wagner A.Chiba de Castro rafael O.xavier Federico H.L.Garrido Jair H.C.Romero Cleto K.Peres Ruberval Cda Luz Instituto Latino-Americano de Ciências da Vida e da Natureza Universidade Federal da Integração Latino-Americana(UNILA)Foz do IguaçuPR85867-970Brazil Departmento de Ecologia Universidade de São PauloSão PauloSP05508-090Brazil Departamento de Hidrobiologia Universidade Federal de São CarlosSão CarlosSP13565-905Brazil

Aims Invasive plants modify the structure and functioning of natural en-vironments and threat native plant *** species are often favored by human interference such as the creation of arti-ficial forest *** removal experiments may clarify if invasive plants are detrimental to native plant regeneration and how this is related to other local *** assessed the joint effect of envir-onment and competition with the invasive Tradescantia zebrina on tree species recruitment in an Atlantic Forest *** We carried out the experimental study in the Iguaçu National Park,located in southern Brazil,using 30 plots distributed across five invaded sites during 6 *** counted *** leaves and recorded the abundance and height of tree recruits over time under contrasting environmental(forest edge *** interior)and removal(all aboveground biomass,only *** removal,and control)*** analyzed the effects of environment and re-moval treatment using generalized linear mixed *** Findings The invasive species performed better at the forest edge than in the *** higher competitive pressure of *** led to higher mortality and lower height of tree *** removal favored tree recruitment,especially in the forest *** study shows that *** hampers woody species regeneration in tropical Atlantic Forests,especially at the forest edge.

关键词： plant invasion competition forest edge plant recruitment Tradescantia zebrina inch plant removal treatment

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review of the El Soplao Amber Outcrop,Early Cretaceous of Cantabria,Spain

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Acta Geologica Sinica(English Edition) 2010年第4期84卷 959-976页

作者： María NAJARRO Enrique PENALVER Ricardo PEreZ-DE LA FUENTE Jaime ORTEGA-BLANCO Cesar MENOR-SALVAN Eduardo BARRON Carmen SORIANO Idoia ROSALES rafael LOPEZ DEL VALLE Francisco VELASCO Fernando TORNOS Véronique DAVIERO-GOMEZ Bernard GOMEZ xavier DELCLOS Instituto Geologico y Minero de Espana E-28003MadridSpain Departament d'Estratigrafia Paleontologia i Geociencies MarinesFacultat de GeologiaUniversitat de BarcelonaE-08071BarcelonaSpain Centro de Astrobiologia(CSIC-INTA) E-28850Torrejon de ArdozSpain European Synchrotron Radiation Facilities F-38000 GrenobleFrance/Geosciences Rennes-Universite de Rennes 1F-35042 RennesFrance El Soplao S.L. Prao El CollaoE-39553CantabriaSpain Universidad del Pais Vasco Dpto.Mineralogia y PetrologiaE-48080 BilbaoSpain CNRS-UMR 5125 PEPS Universite Lyon 1GeodeF-69622 VilleurbanneFrance

El Soplao outcrop, an Early Cretaceous amber deposit recently discovered in northern Spain （Cantabria）, has been shown to be the largest site of amber with arthropod inclusions that has been found in Spain so far. relevant data provided herein for biogeochemistry of the amber, palynology, taphonomy and arthropod bioinclusions complement those previously published. This set of data suggests at least two botanical sources for the amber of El Soplao deposit. The first （type A amber） strongly supports a source related to Cheirolepidiaceae, and the second （type B amber） shows non-specific conifer biomarkers. Comparison of molecular composition of type A amber with Frenelopsis leaves （Cheirolepidiaceae） strongly suggests a biochemical affinity and a common botanical origin. A preliminary palynological study indicates a regional high taxonomical diversity, mainly of pteridophyte spores and gymnosperm pollen grains. According to the preliminary palynological data, the region was inhabited by conifer forests adapted to a dry season under a subtropical climate. The abundant charcoalified wood associated with the amber in the same beds is evidence of paleofires that most likely promoted both the resin production and an intensive erosion of the litter, and subsequent great accumulation of amber plus plant cuticles. In addition, for the first time in the fossil record, charcoalified plant fibers as bioinclnsions in amber are reported. Other relevant taphonomic data are the exceptional presence of serpulids and bryozoans on the surfaces of some amber pieces indicating both a long exposure on marine or brackish-water and a mixed assemblage of amber. Lastly, new findings of insect bioiuclusions, some of them uncommon in the fossil record or showing remarkable adaptations, are reported. In conclusion, a documented scenario for the origin of the El Soplao amber outcrop is provided.

关键词： fossil resin chemotaxonomy paleobotany charcoal arthropod bioinclusions taphonomy EarlyAlbian

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