Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites

International audienceCarbonaceous meteorites are thought to be fragments of C-type (carbonaceous) asteroids. Samples of the C-type asteroid (162173) Ryugu were retrieved by the Hayabusa2 spacecraft. We measure the mineralogy, bulk chemical and isotopic compositions of Ryugu samples. They are mainly composed of materials similar to carbonaceous chondrite meteorites, particularly the CI (Ivuna-type) group. The samples consist predominantly of minerals formed in aqueous fluid on a parent planetesimal. The primary minerals were altered by fluids at a temperature of 37 ± 10°C, 5.2 − 0.8 + 0.7 (Stat.) − 2.1 + 1.6 (Syst.) million years after formation of the first solids in the Solar System. After aqueous alteration, the Ryugu samples were likely never heated above ~100°C. The samples have a chemical composition that more closely resembles the Sun’s photosphere than other natural samples do

Layer-by-layer assembly of light-responsive polymeric multilayer systems

Layer-by-Layer (LbL) assembly is a simple and highly versatile method tomodify surfaces and fabricate robust and highly-ordered nanostructured coatingsover almost any type of substrate. Such versatility enables the incorporationof a plethora of building blocks, including materials exhibiting switchableproperties, in a single device through a multitude of complementary intermolecularinteractions. Switchable materials may undergo reversible physicochemicalchanges in response to a variety of external triggers. Althoughmost of the works in the literature have been focusing on stimuli-responsivematerials that are sensitive to common triggers such as pH, ionic strength, ortemperature, much less has been discussed on LbL systems which are sensitiveto non-invasive and easily controlled light stimulus, despite its uniquepotential. This review provides a deep overview of the recent progressesachieved in the design and fabrication of light-responsive LbL polymericmultilayer systems, their potential future challenges and opportunities, andpossible applications. Many examples are given on light-responsive polymericmultilayer assemblies built from metal nanoparticles, functional dyes, and metal oxides. Such stimuli-responsive functional materials, and combinationsamong them, may lead to novel and highly promising nanostructured smartfunctional systems well-suited for a wide range of research fields, includingbiomedicine and biotechnology.The research leading to this work has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement no REGPOT-CT2012-316331-POLARIS, and from QREN (ON.2 - NORTE-01-0124-FEDER-000016). The research was also funded by FEDER through the Competitive Factors Operational Program (COMPETE) and by National funds through the Portuguese Foundation for Science and Technology (FCT) in the scope of the projects PTDC/FIS/115048/2009 and PTDC/CTM-BIO/1814/2012. J. Borges and L. C. Rodrigues contributed equally to this work