Each of the stratified snow layers in the snowpack is characterized by the morphology and size of the constituent snow grains.Selectively identifying the different snow layers is relevant to determining the stability ...Each of the stratified snow layers in the snowpack is characterized by the morphology and size of the constituent snow grains.Selectively identifying the different snow layers is relevant to determining the stability of the snowpack.We performed on-field Raman spectroscopy measurements in the Monterosa area(Aosta Valley,Italy)to characterize different snowpacks.We observed that the fine features of the Raman spectrum of snow correlate with the snow Specific Surface Area.We clearly distinguished the spectra of aged snow(larger grains,lower specific surface area value)from freshly deposited snow(smaller grains,higher values of specific surface area).Close to the snow melting point,we observed changes in the spectral features of snow associated with the presence of a fraction of liquid water in the snowpack.A portable Raman equipment allows for on-field characterization of the snowpack.展开更多
We introduce a family of membrane-targeted azobenzenes(MTs)with a push-pull character as a new tool for cell stimulation.These molecules are water soluble and spontaneously partition in the cell membrane.Upon light ir...We introduce a family of membrane-targeted azobenzenes(MTs)with a push-pull character as a new tool for cell stimulation.These molecules are water soluble and spontaneously partition in the cell membrane.Upon light irradiation,they isomerize from trans to cis,changing the local charge distribution and thus stimulating the cell response.Specifically,MTs photoisomerization induces clear and reproducible depolarization.The most promising species,MTP2,was extensively studied.Time-resolved spectroscopy techniques provide insights into the excited state evolution and a complete understanding of its isomerization reaction.Molecular Dynamics simulations reveal the spontaneous and stable partitioning of the compound into the cellular membrane,without significant alterations to the bilayer thickness.MTP2 was tested in different cell types,including HEK293T cells,primary neurons,and cardiomyocytes,and a steady depolarization is always recorded.The observed membrane potential modulation in in-vitro models is attributed to the variation in membrane surface charge,resulting from the light-driven modulation of the MT dipole moment within the cell membrane.Additionally,a developed mathematical model successfully captures the temporal evolution of the membrane potential upon photostimulation.Despite being insufficient for triggering action potentials,the rapid light-induced depolarization holds potential applications,particularly in cardiac electrophysiology.Low-intensity optical stimulation with these modulators could influence cardiac electrical activity,demonstrating potential efficacy in destabilizing and terminating cardiac arrhythmias.We anticipate the MTs approach to find applications in neuroscience,biomedicine,and biophotonics,providing a tool for modulating cell physiology without genetic interventions.展开更多
基金Open access funding provided by Politecnico di Milano within the CRUI-CARE Agreement。
文摘Each of the stratified snow layers in the snowpack is characterized by the morphology and size of the constituent snow grains.Selectively identifying the different snow layers is relevant to determining the stability of the snowpack.We performed on-field Raman spectroscopy measurements in the Monterosa area(Aosta Valley,Italy)to characterize different snowpacks.We observed that the fine features of the Raman spectrum of snow correlate with the snow Specific Surface Area.We clearly distinguished the spectra of aged snow(larger grains,lower specific surface area value)from freshly deposited snow(smaller grains,higher values of specific surface area).Close to the snow melting point,we observed changes in the spectral features of snow associated with the presence of a fraction of liquid water in the snowpack.A portable Raman equipment allows for on-field characterization of the snowpack.
基金supported by Telethon-Italy(project#GMR22T2013)The Italian Ministry of Health(project Ricerca Finalizzata#GR-2021-12374630)+4 种基金H2020-MSCA-ITN 2019“Entrain Vision”(project 861423)The Italian Ministry of University and Research(PRIN2020 project#2020XBFEMS)IRCCS Ospedale Policlinico San Martino(Ricerca Corrente and 5×1000 grants)G.M.P.thanks the European Union(ERC,EOS,101115925)for financial supportG.F.acknowledges support by the ERC project SOPHY under grant agreement no.771528。
文摘We introduce a family of membrane-targeted azobenzenes(MTs)with a push-pull character as a new tool for cell stimulation.These molecules are water soluble and spontaneously partition in the cell membrane.Upon light irradiation,they isomerize from trans to cis,changing the local charge distribution and thus stimulating the cell response.Specifically,MTs photoisomerization induces clear and reproducible depolarization.The most promising species,MTP2,was extensively studied.Time-resolved spectroscopy techniques provide insights into the excited state evolution and a complete understanding of its isomerization reaction.Molecular Dynamics simulations reveal the spontaneous and stable partitioning of the compound into the cellular membrane,without significant alterations to the bilayer thickness.MTP2 was tested in different cell types,including HEK293T cells,primary neurons,and cardiomyocytes,and a steady depolarization is always recorded.The observed membrane potential modulation in in-vitro models is attributed to the variation in membrane surface charge,resulting from the light-driven modulation of the MT dipole moment within the cell membrane.Additionally,a developed mathematical model successfully captures the temporal evolution of the membrane potential upon photostimulation.Despite being insufficient for triggering action potentials,the rapid light-induced depolarization holds potential applications,particularly in cardiac electrophysiology.Low-intensity optical stimulation with these modulators could influence cardiac electrical activity,demonstrating potential efficacy in destabilizing and terminating cardiac arrhythmias.We anticipate the MTs approach to find applications in neuroscience,biomedicine,and biophotonics,providing a tool for modulating cell physiology without genetic interventions.
