检索结果-南通市图书馆

Impedance spectroscopy of the cell/nanovolcano interface enables optimization for electrophysiology

在线全文

学校读者我要写书评

暂无评论

微系统与纳米工程(英文) 2023年第3期9卷 297-308页

作者： Nicolas Maïno arnaud Bertsch Philippe Renaud Microsystems laboratory 4 Institute of Electrical and Micro EngineeringEcole Polytechique Fédérale de Lausanne(EPFL)LausanneSwitzerland

Volcano-shaped microelectrodes have demonstrated superior performance in measuring attenuated intracellular action potentials from cardiomyocyte cultures. However, their application to neuronal cultures has not yet yielded reliable intracellular access. This common pitfall supports a growing consensus in the field that nanostructures need to be pitched to the cell of interest to enable intracellular access. Accordingly, we present a new methodology that enables us to resolve the cell/probe interface noninvasively through impedance spectroscopy. This method measures changes in the seal resistance of single cells in a scalable manner to predict the quality of electrophysiological recordings. In particular, the impact of chemical functionalization and variation of the probe’s geometry can be quantitatively measured. We demonstrate this approach on human embryonic kidney cells and primary rodent neurons. Through systematic optimization, the seal resistance can be increased by as much as 20-fold with chemical functionalization, while different probe geometries demonstrated a lower impact. The method presented is therefore well suited to the study of cell coupling to probes designed for electrophysiology, and it is poised to contribute to elucidate the nature and mechanism of plasma membrane disruption by micro/nanostructures.

关键词： enable interface optimization

The Bafoussam volcanic series:origin and evolution of the volcanism along the Cameroon volcanic line

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Geochimica 2022年第6期41卷 1049-1068页

作者： Philippe Essomba Gilles Chazot Nicaise Blaise Tchuimegnie Ngongang arnaud Agranier Pierre Kamgang HervéBellon Philippe Nonnotte Pierre Wotchoko Innocent Badriyo Département Des Sciences de La Terre FacultéDes SciencesUniversitéde YaoundéIB.P.812YaoundéCameroun Geo-Ocean CNRSIfremerUMR6538Univ Brest29280PlouzaneFrance Département Des Sciences de La Terre FacultéDes SciencesUniversitéde DoualaDoualaCameroun Department of Geology Higher Teacher Training CollegeUniversity of BamendaBambiliBamendaCameroon Département de Séismologie et Géologie Observatoire Volcanologique de Goma-RDCGomaRépublique Démocratique du Congo

The Bafoussam area in western Cameroon is part of the central Cameroon Volcanic Ligne(CVL).This study presents the mineralogy,major and trace element compositions,Sr-Pb-Hf isotopes,and new K-Ar geochronological data about mafic and felsic volcanic *** rocks belong to two different series:A transitional series made of basalts,basaltic andesite,and trachytes and an alkaline mafic series with basalts,hawaiites,and *** age data show that the transitional series belongs to the oldest part of the CVL and was emplaced between 47 and 35 *** alkaline volcanism is younger,with ages ranging from10 to 4.5 *** evolution in both series is accomplished through a fractional crystallization process,with the removal of olivine and clinopyroxene,while plagioclase does not seem to be a major crystallizing *** the samples are enriched in incompatible trace elements,but the rocks from the alkaline series have more fractionated REE patterns and high Nb content compared to the transitional mafic *** lavas have lower initial^(87)Sr/^(86)Sr and higher^(176)Hf/^(177)Hf and Pb isotopic ratios than the transitional *** La/Nb and high^(87)Sr/^(86)Sriratio are among chemical characteristics that show that some samples from the transitional series have interacted with a crustal component during their evolution in the *** cannot be used for discussing the mantle source of the volcanic rocks from this *** elements show that primary magmas for both series formed in a garnet-bearing mantle source,with higher partial melting degrees(3-5%)for the transitional magmas than for the alkaline magmas(<2.5%).Combining trace elements and isotopic ratios,we show that the Bafoussam lavas formed from two different mantle *** magmas formed from a pyroxenite-bearing enriched mantle with low Pb isotopic *** mantle source is present in all the oldest lavas from the *** magmas formed from an HIMU-like mantle sourc

关键词： Cameroon Volcanic Line Bafoussam Mafic volcanic rocks Felsic volcanic rocks Mantle source

Removing harvest residues from hardwood stands affects tree growth, wood density and stem wood nutrient concentration in European beech (Fagus sylvatica) and oak (Quercus spp.)

在线全文

学校读者我要写书评

暂无评论

Forest Ecosystems 2022年第2期9卷 147-159页

作者： Sanjoy Roy Jean-Michel Leban Bernhard Zeller Gregory van der Heijden arnaud Reichard Marie-Christine Gehin Philippe Santenoise Laurent Saint-Andre INRAE BEFF-54000 NancyFrance IGN Laboratoire de l’Inventaire ForestierNancyF-54000France Universite de Lorraine AgroParisTechINRAESILVAF-54000 NancyFrance

Background:Higher exportation of harvest residues from forests due to increased demand for woody biomass,has reportedly diminished soil mineral resources and may lead to degraded tree nutrition as well as ***,as nutrients become less available in the soil,the remobilization of nutrients in biomass tissues(plant internal cycling)helps sustain tree *** study aims to quantify the impact of Removing Harvest Residues and Litter(RHRL)during five years on tree growth,wood density,and stem wood nutrient concentrations in young beech and oak forest ***:Our study found that,RHRL significantly decreased tree growth ring width by 14%,and wood density by 3%,in beech trees,in near bark *** also significantly reduced nutrient concentration in near bark and near pith areas of both studied ***,Na and S were found lower by 44%,76%,and 56%,respectively,in near bark area of beech *** near bark area of oak trees,K,Ca,Mg,Na,S,and Fe were lower by 20%,25%,41%,48%,41%,and 16%,respectively.K and Mg concentrations decreased more strongly in near pith area compared to near bark area suggesting internal translocation of these two ***:In beech trees,wood density proved to be an important factor while quantifying the effect of removing harvest residuals on tree growth and *** nutrient loss intensified the remobilization of nutrients con-tained in older tree rings(close to the pith)towards newly formed rings(close to bark).In our study,in beech trees,K was found to be the most recycled major *** results demonstrate the potential of such analysis for providing valuable insight into the effect of RHRL in premature stands on the physiological adaptive strategies of trees and an indication of soil fertility status.

关键词： Harvest residues Fagus sylvatica Quercus petraea Dendroecology Dendrochemistry Radial growth Wood density Tree growth Ring width Translocation

A Sophisticated Network of Signaling Pathways Regulates Stomatal Defenses to Bacterial Pathogens

在线全文

学校读者我要写书评

暂无评论

Molecular Plant 2015年第4期8卷 566-581页

作者： Dominique arnaud Ildoo Hwang Department of Life Sciences POSTECH Biotech Center Pohang University of Science and Technology Pohang /90-/84 Korea

Guard cells are specialized cells forming stomatal pores at the leaf surface for gas exchanges between the plant and the atmosphere. Stomata have been shown to playan important role in plant defense as a part of the innate immune response. Plants actively close their stomata upon contact with microbes, thereby preventing pathogen entry into the leaves and the subsequent colonization of host tissues. In this review, we present current knowledge of molecular mechanisms and signaling pathways implicated in stomatal defenses, with particular emphasis on plant-bacteria interactions. Stomatal defense responses begin from the perception of pathogen-associated molecular patterns （PAMPs） and activate a signaling cascade involving the production of secondary messengers such as reactive oxygen species, nitric oxide, and calcium for the regulation of plasma membrane ion channels. The analyses on downstream molecular mechanisms implicated in PAMP-triggered stomatal closure have revealed extensive interplays among the components regulating hormonal signaling pathways. We also discuss the strategies deployed by pathogenic bacteria to counteract stomatal immunity through the example of the phytotoxin coronatine.

关键词： stomata immunity hydrogen peroxide nitric oxide calcium hormones

On the Controllability of an Advection-diffusion Equation with Respect to the Diffusion Parameter:Asymptotic Analysis and Numerical Simulations

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2019年第1期35卷 54-110页

作者： Youcef AMIRAT arnaud MNCH Laboratoire de Mathématiques Blaise Pascal Université Clermont Auvergne UMR CNRS 6620 Campus universitaire des Cézeaux

The advection-diffusion equation y_t~ε-εy_(xx)~ε+ M y_x~ε= 0,(x, t) ∈(0, 1) ×(0, T) is null controllable for any strictly positive values of the diffusion coefficient ε and of the controllability time T. We discuss here the behavior of the cost of control when the coefficient ε goes to zero, according to the values of T. It is actually known that this cost is uniformly bounded with respect to ε if T is greater than a minimal time T_M, with T_M in the interval [1, 2×3^(1/2)]/M for M > 0 and in the interval [2×2^(1/2), 2(1 +3^(1/2))]/|M | for M < 0. The exact value of TM is however *** investigate in this work the determination of the minimal time T_M employing two distincts but complementary approaches. In a first one, we numerically estimate the cost of controllability, reformulated as the solution of a generalized eigenvalue problem for the underlying control operator, with respect to the parameter T and ε. This allows notably to exhibit the structure of initial data leading to large costs of control. At the practical level, this evaluation requires the non trivial and challenging approximation of null controls for the advection-diffusion equation. In the second approach, we perform an asymptotic analysis, with respect to the parameter ε, of the optimality system associated to the control of minimal L^2-norm. The matched asymptotic expansion method is used to describe the multiple boundary layers.

关键词： numerical approximation space-time variational formulation asymptotic analysis boundary layers null controllability

Functionalized liposomes for targeted breast cancer drug delivery

在线全文

学校读者我要写书评

暂无评论

Bioactive Materials 2023年第6期24卷 401-437页

作者： Janske Nel Kamil Elkhoury Émilie Velot arnaud Bianchi Samir Acherar Grégory Francius Ali Tamayol Stéphanie Grandemange Elmira Arab-Tehrany Universitéde Lorraine LIBioF-54000NancyFrance LAAS-CNRS F-31400ToulouseFrance Universitéde Lorraine CNRSIMoPAF-54000NancyFrance Universitéde Lorraine CNRSLCPMF-54000NancyFrance Universitéde Lorraine CNRSLCPMEF-54000NancyFrance Department of Biomedical Engineering University of Connecticut Health CenterFarmingtonCT06030USA Universitéde Lorraine CNRSCRANF-54000NancyFrance

Despite the exceptional progress in breast cancer pathogenesis,prognosis,diagnosis,and treatment strategies,it remains a prominent cause of female mortality ***,although chemotherapies are effective,they are associated with critical limitations,most notably their lack of specificity resulting in systemic toxicity and the eventual development of multi-drug resistance(MDR)cancer *** have proven to be an invaluable drug delivery system but of the multitudes of liposomal systems developed every year only a few have been approved for clinical use,none of which employ active *** this review,we summarize the most recent strategies in development for actively targeted liposomal drug delivery systems for surface,transmembrane and internal cell receptors,enzymes,direct cell targeting and dual-targeting of breast cancer and breast cancer-associated cells,e.g.,cancer stem cells,cells associated with the tumor microenvironment,etc.

关键词： Liposomes Breast cancer Anti-cancer agents Targeted drug delivery Surface functionalization Receptor-targeted drug delivery

Rapid prototyping of a polymer MEMS dropletdispenser by laser-assisted 3D printing

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Microsystems & Nanoengineering 2023年第4期9卷 211-221页

作者： Rémi Courson Oleksii Bratash Ali Maziz CloéDesmet Ricardo Alvarado Meza Loïc Leroy Elodie Engel arnaud Buhot Laurent Malaquin Thierry Leïchlé LAAS-CNRS Universitéde ToulouseCNRS31400 ToulouseFrance UniversitéGrenoble Alpes CNRSCEAIRIGSyMMES38000 GrenobleFrance Georgia Tech−CNRS International Research Laboratory AtlantaGA 30332USA

In this work, we introduce a polymer version of a previously developed silicon MEMS drop deposition tool for surfacefunctionalization that consists of a microcantilever integrating an open fluidic channel and a reservoir. The device isfabricated by laser stereolithography, which offers the advantages of low-cost and fast prototyping. Additionally,thanks to the ability to process multiple materials, a magnetic base is incorporated into the cantilever for convenienthandling and attachment to the holder of a robotized stage used for spotting. Droplets with diameters ranging from∼50 μm to ∼300 μm are printed upon direct contact of the cantilever tip with the surface to pattern. Liquid loading isachieved by fully immersing the cantilever into a reservoir drop, where a single load results in the deposition of morethan 200 droplets. The influences of the size and shape of the cantilever tip and the reservoir on the printing outcomeare studied. As a proof-of-concept of the biofunctionalization capability of this 3D printed droplet dispenser,microarrays of oligonucleotides and antibodies displaying high specificity and no cross-contamination are fabricated,and droplets are deposited at the tip of an optical fiber bundle.

关键词： cantilever reservoir printing

Enhanced weathering input from South Asia to the Indian Ocean since the late Eocene

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science Bulletin 2023年第3期68卷 305-313,M0004页

作者： Zehua Song Shiming Wan Christophe Colin Christian France-Lanord Zhaojie Yu arnaud Dapoigny Hualong Jin Mengjun Li Jin Zhang Debo Zhao Xuefa Shi Anchun Li Key Laboratory of Marine Geology and Environment Institute of OceanologyChinese Academy of SciencesQingdao 266071China Laboratory for Marine Geology Qingdao National Laboratory for Marine Science and TechnologyQingdao 266061China UniversitéParis-Saclay Centre National de la Recherche Scientifique(CNRS)Géosciences Paris-Saclay(GEOPS)Orsay 91405France Center for Excellence in Quaternary Science and Global Change Chinese Academy of SciencesXi’an 710061China Centre de Recherches Pétrographiques et Géochimiques(CRPG) Centre National de la Recherche Scientifique(CNRS)-Universitéde LorraineVandoeuvre les Nancy 54501France Laboratoire des Sciences du Climat et de l’Environnement LSCE/IPSLCEA-CNRS-UVSQUniversitéParis-SaclayGif-sur-Yvette 91191France Key Laboratory of Marine Sedimentology and Environmental Geology First Institute of OceanographyMinistry of Natural ResourcesQingdao 266061China

nhanced silicate weathering induced by the uplift of the Himalayan-Tibetan Plateau(HTP)has been considered as the major cause of pCO_(2) decline and Cenozoic ***,this hypothesis remains to be validated,largely due to the lack of a reliable reconstruction of the HTP weathering ***,we present a 37-million-year record of the difference in the seawater radiogenic neodymium isotopic composition(△ε_(Nd))of Ocean Drilling Program(ODP)sites and Fe-Mn crusts between the northern and central Indian Ocean,which indicates the contribution of regional weathering input from the South Asian continent to the Indian *** results show a long-term increase in △ε_(Nd) and thus provide the first critical evidence of enhanced South Asian weathering input since the late *** evolution coincided well with major pulses of surface uplift in the HTP and global climatic *** foraminiferal eNd record suggests that tectonic uplift and silicate weathering in South Asia,especially in the Himalayas,might have played a significant role in the late Cenozoic cooling.

关键词： South Asian weathering input Himalayan-Tibetan Plateau uplift Cenozoic global cooling Foraminiferal eNd record Indian Ocean ODP Site 758

Bounded type Siegel disks of finite type maps with few singular values Dedicated to the Memory of Professor Lei Tan

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2018年第12期61卷 2139-2156页

作者： arnaud Chéritat Adam Lawrence Epstein CNRS Institut de Mathematiques de ToulouseUniversite Paul SabatierToulouse F-31062France Mathematics Institute University of WarwickCoventry CV47ALUK

Let U be an open subset of the Riemann sphere C. We give sufficient conditions for which a finite type map f : U →C with at most three singular values has a Siegel disk compactly contained in U and whose boundary is a quasicircle containing a unique critical point. The main tool is quasiconformal surgery à la Douady-Ghys-Herman-(S′)wia tek. We also give sufficient conditions for which, instead, ? has not compact closure in U. The main tool is the Schwarzian derivative and area inequalities à la Graczyk-(S′)wia tek.

关键词： Siegel disks quasicircles quasiconformal surgery Schwarzian derivative