Polymeric Photoacids Based on Naphthols—Design Criteria, Photostability, and Light-Mediated Release

The implementation of photoswitches within polymers offers an exciting toolbox in the design of light-responsive materials as irradiation can be controlled both spatially and temporally. Herein, we introduce a range of water-soluble copolymers featuring naphthol-based chromophores as photoacids in the side chain. With that, the resulting materials experience a drastic increase in acidity upon stimulation with UV light and we systematically studied how structure and distance of the photoacid from the copolymer backbone determines polymerizability, photo-response, and photostability. Briefly, we used RAFT (reversible addition–fragmentation chain transfer) polymerization to prepare copolymers consisting of nona(ethylene glycol) methyl ether methacrylate (MEO9MA) as water-soluble comonomer in combination with six different 1-naphthol-based (“N”) monomers. Thereby, we distinguish between methacrylates (NMA, NOeMA), methacrylamides (NMAm, NOeMAm), vinyl naphthol (VN), and post-polymerization modification based on [(1-hydroxynaphthalen-2-amido)ethyl]amine (NOeMAm, NAmeMAm). These P(MEO9MAx-co-“N”y) copolymers typically feature a 4:1 MEO9MA to “N” ratio and molar masses in the range of 10 kg mol−1. After synthesis and characterization by using NMR spectroscopy and size exclusion chromatography (SEC), we investigated how potential photo-cleavage or photo-degradation during irradiation depends on the type and distance of the linker to the copolymeric backbone and whether reversible excited state proton transfer (ESPT) occurs under these conditions. In our opinion, such materials will be strong assets as light-mediated proton sources in nanostructured environments, for example, for the site-specific creation of proton gradients. We therefore exemplarily incorporated NMA into an amphiphilic block copolymer and could demonstrate the light-mediated release of Nile red from micelles formed in water as selective solvent. © 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA

Quinoline Photobasicity: Investigation within Water-Soluble Light-Responsive Copolymers

Quinoline photobases exhibit a distinctly higher pKa in their electronically excited state than in the ground state, thereby enabling light-controlled proton transfer reactions, for example, in molecular catalysis. The absorption of UV light translates to a pKa jump of approximately 10 units, as established for small-molecule photobases. This contribution presents the first synthesis of quinoline-based polymeric photobases prepared by reversible addition-fragmentation chain-transfer (RAFT) polymerization. The integration of quinolines as photobase chromophores within copolymers offers new possibilities for light-triggered proton transfer in nanostructured materials, that is, in nanoparticles, at surfaces, membranes and interfaces. To exploit the light-triggered reactivity of photobases within such materials, we first investigated how the ground- and excited-state properties of the quinoline unit changes upon polymer integration. To address this matter, we combined absorption and emission spectroscopy with time-resolved transient-absorption studies to reveal photoinduced proton-transfer dynamics in various solvents. The results yield important insights into the thermodynamic and kinetic properties of these polymeric quinoline photobases. © 2020 The Authors. Chemistry - A European Journal published by Wiley-VCH Gmb

Block Copolymers Featuring Highly Photostable Photoacids Based on Vinylnaphthol: Synthesis and Self-Assembly

The synthesis of a photoresponsive amphiphilic diblock quarterpolymer containing 5-vinyl-1-naphthol (VN) as a photostable photoacidic comonomer is presented. The preparation is realized via a sequential reversible addition fragmentation chain transfer (RAFT) polymerization starting from a nona(ethylene glycol) methyl ether methacrylate (MEO9MA/“O”) hydrophilic block, which is then used as a macro-RAFT agent in the terpolymerization of styrene (S), 2-vinylpyridine (2VP), and TBS-protected VN (tVN). The terpolymerization proceeds in a controlled fashion and two diblock quarterpolymers, P(Om)-b-P(Sx-co-2VPy-co-VNz), with varying functional comonomer compositions are prepared. These diblock quarterpolymers form spherical core-corona micelles in aqueous media according to dynamic light scattering (DLS) and cryogenic transmission electron microscopy (cryo-TEM). Upon irradiation, the photoacids within the micellar core experience a drastic increase in acidity causing a proton transfer from the photoacid to neighboring 2VP units. As a result, the hydrophilic/hydrophobic balance of the entire assembly is shifted, and the encapsulated cargo is released. © 2020 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

The April 2016 Muisne (Ecuador) Earthquake : Behaviour of Low-rise RC Frames with Masonry Infill, and Recommendations for New Construction

The 16th April 2016 Mw 7.8 Muisne earthquake in Ecuador caused nearly 700 fatalities, 230,000 injuries and over 35,000 damaged or collapsed homes, leaving 140,000 without adequate housing. The majority of the damaged structures, in particular in urban and peri-urban areas, were constructed from low-rise reinforced concrete frames with unreinforced masonry infill. It was evident by their design that these buildings are generally non-engineered, or at least not correctly engineered, for seismic loads. This paper draws on observations made primarily from the EEFIT reconnaissance mission, augmented from other missions to the affected region, to describe the typical types of damage and failures seen in this building taxonomy, and why these are likely to have occurred. The paper then explores confined masonry as an option for new construction. An example is presented of the successful implementation of confined masonry post-event in the affected region, describing the approach that was adopted, in particular training, promotion and dissemination of the confined masonry technique, as well as the challenges of influencing people’s existing perceptions and styles. The paper concludes with a summary of why confined masonry is considered to be a durable, resilient, easy to construct and appropriate form of new construction in Ecuador.Applied Science, Faculty ofNon UBCCivil Engineering, Department ofUnreviewedFacultyResearcherOthe

Intra-axonal Synthesis of SNAP25 Is Required for the Formation of Presynaptic Terminals

Localized protein synthesis is a mechanism for developing axons to react acutely and in a spatially restricted manner to extracellular signals. As such, it is important for many aspects of axonal development, but its role in the formation of presynapses remains poorly understood. We found that the induced assembly of presynaptic terminals required local protein synthesis. Newly synthesized proteins were detectable at nascent presynapses within 15 min of inducing synapse formation in isolated axons. The transcript for the t-SNARE protein SNAP25, which is required for the fusion of synaptic vesicles with the plasma membrane, was recruited to presynaptic sites and locally translated. Inhibition of intra-axonal SNAP25 synthesis affected the clustering of SNAP25 and other presynaptic proteins and interfered with the release of synaptic vesicles from presynaptic sites. This study reveals a critical role for the axonal synthesis of SNAP25 in the assembly of presynaptic terminals.Portuguese Foundation for Science and Technology (FCT) in the context of the FCT funded University of Minho MD/PhD Program (SFRH/BD/52322/2013). J.C.M. was supported by the National Institutes of Health (F31GM116617). U.H. was supported by the NIH (R01MH096702), the BrightFocus Foundation (A2015093S), and the Irma T. Hirschl Trus

Assessing local building cultures for resilience & development: A practical guide for community-based assessment

International audienceThe development of a set of tools to enhance appreciation of local practices developed by communities regarding settlements and risks is an initiative that aims to promote context-based strategies for responding efficiently and adequately to habitat improvement and vulnerability reduction needs. This guide offers a methodological and operational support for decision-making and practices towards approaches and actions deeply rooted in local contexts. It is a practical tool that provides detailed explanation on planning, preparing and undertaking field assessments of local practices related to habitat and risks. It refers to a participatory approach suitable for, and adapted to, various geographical, cultural and risk-prone areas. By supporting habitat assessment in all its different aspects, it also fosters links between programmes, providing clues and keys to define and implement coherent projects including income generating activities, livelihood, health and other related sectors. The necessary investment to be taken into account in project planning to achieve the basic step described in this booklet will result in huge savings, as logistical issues will be drastically reduced during the project implementation. It is a worthwhile investment that will lead to decisions ensuring more benefits to the affected communities, including a long-term enhancement of their resilience capacityCet ouvrage s'adresse aux responsables de projets et aux preneurs de décisions. L'auteur explique tout d'abord la démarche de projet respectueuse des cultures constructives. L'auteur présente ensuite une méthode d'évaluation des cultures constructives locales et expose l'importance de celle-ci dans un proje