ALBERT

Description: About half of present-day cloud condensation nuclei originate from atmospheric nucleation, frequently appearing as a burst of new particles near midday. Atmospheric observations show that the growth rate of new particles often accelerates when the diameter of the particles is between one and ten nanometres. In this critical size range, new particles are most likely to be lost by coagulation with pre-existing particles, thereby failing to form new cloud condensation nuclei that are typically 50 to 100 nanometres across. Sulfuric acid vapour is often involved in nucleation but is too scarce to explain most subsequent growth, leaving organic vapours as the most plausible alternative, at least in the planetary boundary layer. Although recent studies predict that low-volatility organic vapours contribute during initial growth, direct evidence has been lacking. The accelerating growth may result from increased photolytic production of condensable organic species in the afternoon, and the presence of a possible Kelvin (curvature) effect, which inhibits organic vapour condensation on the smallest particles (the nano-Kohler theory), has so far remained ambiguous. Here we present experiments performed in a large chamber under atmospheric conditions that investigate the role of organic vapours in the initial growth of nucleated organic particles in the absence of inorganic acids and bases such as sulfuric acid or ammonia and amines, respectively. Using data from the same set of experiments, it has been shown that organic vapours alone can drive nucleation. We focus on the growth of nucleated particles and find that the organic vapours that drive initial growth have extremely low volatilities (saturation concentration less than 10(-4.5) micrograms per cubic metre). As the particles increase in size and the Kelvin barrier falls, subsequent growth is primarily due to more abundant organic vapours of slightly higher volatility (saturation concentrations of 10(-4.5) to 10(-0.5) micrograms per cubic metre). We present a particle growth model that quantitatively reproduces our measurements. Furthermore, we implement a parameterization of the first steps of growth in a global aerosol model and find that concentrations of atmospheric cloud concentration nuclei can change substantially in response, that is, by up to 50 per cent in comparison with previously assumed growth rate parameterizations.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Trostl, Jasmin -- Chuang, Wayne K -- Gordon, Hamish -- Heinritzi, Martin -- Yan, Chao -- Molteni, Ugo -- Ahlm, Lars -- Frege, Carla -- Bianchi, Federico -- Wagner, Robert -- Simon, Mario -- Lehtipalo, Katrianne -- Williamson, Christina -- Craven, Jill S -- Duplissy, Jonathan -- Adamov, Alexey -- Almeida, Joao -- Bernhammer, Anne-Kathrin -- Breitenlechner, Martin -- Brilke, Sophia -- Dias, Antonio -- Ehrhart, Sebastian -- Flagan, Richard C -- Franchin, Alessandro -- Fuchs, Claudia -- Guida, Roberto -- Gysel, Martin -- Hansel, Armin -- Hoyle, Christopher R -- Jokinen, Tuija -- Junninen, Heikki -- Kangasluoma, Juha -- Keskinen, Helmi -- Kim, Jaeseok -- Krapf, Manuel -- Kurten, Andreas -- Laaksonen, Ari -- Lawler, Michael -- Leiminger, Markus -- Mathot, Serge -- Mohler, Ottmar -- Nieminen, Tuomo -- Onnela, Antti -- Petaja, Tuukka -- Piel, Felix M -- Miettinen, Pasi -- Rissanen, Matti P -- Rondo, Linda -- Sarnela, Nina -- Schobesberger, Siegfried -- Sengupta, Kamalika -- Sipila, Mikko -- Smith, James N -- Steiner, Gerhard -- Tome, Antonio -- Virtanen, Annele -- Wagner, Andrea C -- Weingartner, Ernest -- Wimmer, Daniela -- Winkler, Paul M -- Ye, Penglin -- Carslaw, Kenneth S -- Curtius, Joachim -- Dommen, Josef -- Kirkby, Jasper -- Kulmala, Markku -- Riipinen, Ilona -- Worsnop, Douglas R -- Donahue, Neil M -- Baltensperger, Urs -- England -- Nature. 2016 May 25;533(7604):527-31. doi: 10.1038/nature18271.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Paul Scherrer Institute, Laboratory of Atmospheric Chemistry, CH-5232 Villigen, Switzerland. ; Carnegie Mellon University, Center for Atmospheric Particle Studies, Pittsburgh, Pennsylvania 15213, USA. ; CERN, CH-1211 Geneva, Switzerland. ; Goethe University Frankfurt, Institute for Atmospheric and Environmental Sciences, 60438 Frankfurt am Main, Germany. ; Department of Physics, University of Helsinki, PO Box 64, FI-00014 Helsinki, Finland. ; Department of Applied Environmental Science, University of Stockholm, SE-10961 Stockholm, Sweden. ; Institute for Atmospheric and Climate Science, ETH Zurich, 8092 Zurich, Switzerland. ; Chemical Sciences Division, Earth System Research Laboratory, NOAA, Boulder, Colorado, USA. ; Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA. ; Helsinki Institute of Physics, University of Helsinki, PO Box 64, FI-00014 Helsinki, Finland. ; Institute for Ion and Applied Physics, University of Innsbruck, 6020 Innsbruck, Austria. ; Ionicon Analytik GmbH, 6020 Innsbruck, Austria. ; WSL Institute for Snow and Avalanche Research SLF, 7260 Davos, Switzerland. ; University of Eastern Finland, 70211 Kuopio, Finland. ; Finnish Meteorological Institute, 00101 Helsinki, Finland. ; National Center for Atmospheric Research, Atmospheric Chemistry Observations and Modeling Laboratory, Boulder, Colorado 80301, USA. ; Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, Karlsruhe, Germany. ; School of Earth and Environment, University of Leeds, LS2 9JT Leeds, UK. ; Department of Chemistry, University of California, Irvine, California 92697, USA. ; Faculty of Physics, University of Vienna, 1090 Vienna, Austria. ; SIM, University of Lisbon and University of Beira Interior, 1849-016 Lisbon, Portugal. ; Aerodyne Research, Inc., Billerica, Massachusetts 01821, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/27225126" target="_blank"〉PubMed〈/a〉

Description: Atmospheric aerosols and their effect on clouds are thought to be important for anthropogenic radiative forcing of the climate, yet remain poorly understood. Globally, around half of cloud condensation nuclei originate from nucleation of atmospheric vapours. It is thought that sulfuric acid is essential to initiate most particle formation in the atmosphere, and that ions have a relatively minor role. Some laboratory studies, however, have reported organic particle formation without the intentional addition of sulfuric acid, although contamination could not be excluded. Here we present evidence for the formation of aerosol particles from highly oxidized biogenic vapours in the absence of sulfuric acid in a large chamber under atmospheric conditions. The highly oxygenated molecules (HOMs) are produced by ozonolysis of alpha-pinene. We find that ions from Galactic cosmic rays increase the nucleation rate by one to two orders of magnitude compared with neutral nucleation. Our experimental findings are supported by quantum chemical calculations of the cluster binding energies of representative HOMs. Ion-induced nucleation of pure organic particles constitutes a potentially widespread source of aerosol particles in terrestrial environments with low sulfuric acid pollution.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kirkby, Jasper -- Duplissy, Jonathan -- Sengupta, Kamalika -- Frege, Carla -- Gordon, Hamish -- Williamson, Christina -- Heinritzi, Martin -- Simon, Mario -- Yan, Chao -- Almeida, Joao -- Trostl, Jasmin -- Nieminen, Tuomo -- Ortega, Ismael K -- Wagner, Robert -- Adamov, Alexey -- Amorim, Antonio -- Bernhammer, Anne-Kathrin -- Bianchi, Federico -- Breitenlechner, Martin -- Brilke, Sophia -- Chen, Xuemeng -- Craven, Jill -- Dias, Antonio -- Ehrhart, Sebastian -- Flagan, Richard C -- Franchin, Alessandro -- Fuchs, Claudia -- Guida, Roberto -- Hakala, Jani -- Hoyle, Christopher R -- Jokinen, Tuija -- Junninen, Heikki -- Kangasluoma, Juha -- Kim, Jaeseok -- Krapf, Manuel -- Kurten, Andreas -- Laaksonen, Ari -- Lehtipalo, Katrianne -- Makhmutov, Vladimir -- Mathot, Serge -- Molteni, Ugo -- Onnela, Antti -- Perakyla, Otso -- Piel, Felix -- Petaja, Tuukka -- Praplan, Arnaud P -- Pringle, Kirsty -- Rap, Alexandru -- Richards, Nigel A D -- Riipinen, Ilona -- Rissanen, Matti P -- Rondo, Linda -- Sarnela, Nina -- Schobesberger, Siegfried -- Scott, Catherine E -- Seinfeld, John H -- Sipila, Mikko -- Steiner, Gerhard -- Stozhkov, Yuri -- Stratmann, Frank -- Tome, Antonio -- Virtanen, Annele -- Vogel, Alexander L -- Wagner, Andrea C -- Wagner, Paul E -- Weingartner, Ernest -- Wimmer, Daniela -- Winkler, Paul M -- Ye, Penglin -- Zhang, Xuan -- Hansel, Armin -- Dommen, Josef -- Donahue, Neil M -- Worsnop, Douglas R -- Baltensperger, Urs -- Kulmala, Markku -- Carslaw, Kenneth S -- Curtius, Joachim -- England -- Nature. 2016 May 25;533(7604):521-6. doi: 10.1038/nature17953.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Goethe University Frankfurt, Institute for Atmospheric and Environmental Sciences, 60438 Frankfurt am Main, Germany. ; CERN, CH-1211 Geneva, Switzerland. ; Department of Physics, University of Helsinki, FI-00014 Helsinki, Finland. ; Helsinki Institute of Physics, University of Helsinki, FI-00014 Helsinki, Finland. ; School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK. ; Paul Scherrer Institute, Laboratory of Atmospheric Chemistry, CH-5232 Villigen, Switzerland. ; Institute for Ion and Applied Physics, University of Innsbruck, 6020 Innsbruck, Austria. ; Onera-The French Aerospace Lab, F-91123 Palaiseau, France. ; SIM, University of Lisbon, 1849-016 Lisbon, Portugal. ; Ionicon Analytik GmbH, 6020 Innsbruck, Austria. ; Institute for Atmospheric and Climate Science, ETH Zurich, CH-8092 Zurich, Switzerland. ; Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA. ; WSL Institute for Snow and Avalanche Research SLF, CH-7260 Davos, Switzerland. ; University of Eastern Finland, FI-70211 Kuopio, Finland. ; Finnish Meteorological Institute, FI-00101 Helsinki, Finland. ; Solar and Cosmic Ray Research Laboratory, Lebedev Physical Institute, 119991 Moscow, Russia. ; University of Leeds, National Centre for Earth Observation, Leeds LS2 9JT, UK. ; Department of Applied Environmental Science, University of Stockholm, SE-10961 Stockholm, Sweden. ; Faculty of Physics, University of Vienna, 1090 Vienna, Austria. ; Leibniz Institute for Tropospheric Research, 04318 Leipzig, Germany. ; University of Beira Interior, 6201-001 Covilha, Portugal. ; Center for Atmospheric Particle Studies, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA. ; Aerodyne Research Inc., Billerica, Massachusetts 01821, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/27225125" target="_blank"〉PubMed〈/a〉

Description: Nanog, a core pluripotency factor in the inner cell mass of blastocysts, is also expressed in unipotent primordial germ cells (PGCs) in mice, where its precise role is yet unclear. We investigated this in an in vitro model, in which naive pluripotent embryonic stem (ES) cells cultured in basic fibroblast growth factor (bFGF) and activin A develop as epiblast-like cells (EpiLCs) and gain competence for a PGC-like fate. Consequently, bone morphogenetic protein 4 (BMP4), or ectopic expression of key germline transcription factors Prdm1, Prdm14 and Tfap2c, directly induce PGC-like cells (PGCLCs) in EpiLCs, but not in ES cells. Here we report an unexpected discovery that Nanog alone can induce PGCLCs in EpiLCs, independently of BMP4. We propose that after the dissolution of the naive ES-cell pluripotency network during establishment of EpiLCs, the epigenome is reset for cell fate determination. Indeed, we found genome-wide changes in NANOG-binding patterns between ES cells and EpiLCs, indicating epigenetic resetting of regulatory elements. Accordingly, we show that NANOG can bind and activate enhancers of Prdm1 and Prdm14 in EpiLCs in vitro; BLIMP1 (encoded by Prdm1) then directly induces Tfap2c. Furthermore, while SOX2 and NANOG promote the pluripotent state in ES cells, they show contrasting roles in EpiLCs, as Sox2 specifically represses PGCLC induction by Nanog. This study demonstrates a broadly applicable mechanistic principle for how cells acquire competence for cell fate determination, resulting in the context-dependent roles of key transcription factors during development.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4724940/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4724940/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Murakami, Kazuhiro -- Gunesdogan, Ufuk -- Zylicz, Jan J -- Tang, Walfred W C -- Sengupta, Roopsha -- Kobayashi, Toshihiro -- Kim, Shinseog -- Butler, Richard -- Dietmann, Sabine -- Surani, M Azim -- 092096/Wellcome Trust/United Kingdom -- C6946/A14492/Cancer Research UK/United Kingdom -- RG44593/Wellcome Trust/United Kingdom -- WT096738/Wellcome Trust/United Kingdom -- England -- Nature. 2016 Jan 21;529(7586):403-7. doi: 10.1038/nature16480. Epub 2016 Jan 11.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK. ; Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK. ; Wellcome Trust Medical Research Council Stem Cell Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK. ; Laboratory for Pluripotent Cell Studies, Center for Developmental Biology, RIKEN, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan. ; Laboratory for Molecular and Cellular Biology, Faculty of Advanced Life Science, Hokkaido University, Kita21 Nishi11, Kita-ku, Sapporo, Hokkaido 001-0021, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26751055" target="_blank"〉PubMed〈/a〉