Designing identity of a new material: a new product design approach

The present research is a design practice-based research based on the industrial development of a new concrete. The research focuses on the development of the specific identity of a new material. The research is aimed at demonstrating that product design can be used as a new strategy to create the material identity and thus to differentiate from existing materials. In order to design material specific identity in new products, we need to understand the perception process of shaped materials. Therefore we conducted exploratory study of materials recognition in products. We identified two types of products: the “messenger” products are specific shapes characteristic from the material; the “wrong messenger” products are imitations of other well known materials. The results of questionnaire about material recognition show that it’s more or less easy to identify material according to each product (whether it’s familiar or new shapes; whether it’s imitation or specific shapes and whether it’s well known or new material). We conclude on two types of shapes: on the one hand some familiar and typical shapes make easier and more certain the material recognition; on the other hand some new shapes make people more uncertain of what it is made of but more amazed. Designing amazing new shapes can be used as a new differentiation strategy to create the specific sensory identity of each new material. It means that the product can be a really useful support to fully communicate about a new material, beyond the traditional material samples. Keywords: New Material; Sensory Identity; Product Design</p

Physics, biology and the right chemistry

Joint studies that involve biologists and physicists are becoming more frequent and have contributed to the identification and understanding of physical parameters underlying key biological processes. Here, we illustrate the main findings resulting from a 10-year collaboration between a cell biologist and an experimental physicist, both interested in the mechanisms of intracellular transport and membrane dynamics in eukaryotic cells

Focus on the physics of the cell membrane

This focus issue on membrane biophysics presents a collection of papers illustrating new developments in modern biophysical research on cell membranes. The work described here addresses questions from a broad range of areas, including cell adhesion, membrane trafficking and activation of cells of the immune system. It also presents recent views on membrane mechanics, the effect of electric fields, as well as on the interplay of mechanics and chemistry and organization at many different scales

Dynamics of Membrane Tethers Reveal Novel Aspects of Cytoskeleton-Membrane Interactions in Axons

AbstractMechanical properties of cell membranes are known to be significantly influenced by the underlying cortical cytoskeleton. The technique of pulling membrane tethers from cells is one of the most effective ways of studying the membrane mechanics and the membrane-cortex interaction. In this article, we show that axon membranes make an interesting system to explore as they exhibit both free membrane-like behavior where the tether-membrane junction is movable on the surface of the axons (unlike many other cell membranes) as well as cell-like behavior where there are transient and spontaneous eruptions in the tether force that vanish when F-actin is depolymerized. We analyze the passive and spontaneous responses of axonal membrane tethers and propose theoretical models to explain the observed behavior

O USO DOS NOVOS BIOCERÂMICOS NA MICROCIRURGIA ENDODÔNTICA - Revisão sistemática integrativa

Introdução: A microcirurgia endodôntica é necessária para garantir um melhor resultado quando o tratamento não cirúrgico está contraindicado. A seleção do material retro-obturador é muito importante porque deve apresentar boas características biológicas e físicas. O MTA é atualmente considerado o gold standard, mas apresenta várias desvantagens. Assim foi desenvolvida uma vasta gama de novos materiais biocerâmicos para melhorar os resultados da retro-preparação como a Biodentine, o EndoSequence e o BioAggregate. Objetivos: Verificar se os novos materiais biocerâmicos são uma alternativa adequada ao MTA na microcirurgia endodôntica e se ultrapassam as desvantagens deste material. Material e métodos: Foi realizada uma pesquisa bibliográfica na base de dados Pubmed, considerando artigos publicados em inglês entre 2011 e 2021, utilizando as seguintes palavras-chave: «microsurgery», «human», «root end», «silicates», «root canal filling materials», «calcium compounds». Resultados: Foram selecionados 14 artigos, considerados pertinentes sobre os materiais retro-obturadores. Dos quais 5 abordam as propriedades biológicas dos novos biocerâmicos, 4 estudam a impermeabilização e a qualidade do selamento, 2 analisam as propriedades físicas dos materiais e por fim, 3 analisam outras características como a radiopacidade, o manuseamento ou o tempo de presa. Discussão: Os novos biocerâmicos apresentam características biológicas e físicas pelo menos tão boas como o MTA. As suas capacidades de selamento são também adequadas, o que é crucial para o sucesso deste tratamento. Asseguram também um tempo de presa mais curto e um melhor manuseamento, o que facilita as suas utilizações. Conclusão: Podemos considerar os novos biocerâmicos como uma solução alternativa ao MTA no tratamento da microcirurgia endodôntica

Les Petites Affiches : textilisation of architectural memory through the transformation of rubble

This paper will introduce a practice-based and design-led investigation using Les Petites Affiches– a rehabilitation project by the architectural agency SCAU - as a key site of experimentation for a PhD project fully integrated in the daily life of the agency. The research, informed by a textile design practice, investigates new modes of transmission based on the in situ transformation of rubble - as an alternative to «tabula rasa» or strict restoration. Instead of being thrown away, rubble are conceptually and materially integrated in the new architectural project as for instance : pigments, fabrics or floor surfaces. The transmaterialised memory of the past building therefore becomes a constitutive component of the future structure. In the case study of Les Petites Affiches, a Parisian building dating back to 1922 and subject to rehabilitation between 2017-2018, 111.39 kg of rubble were collected to explore how they could be textilised. In other words, the experiment - developed during an on-site-residency -, focused on how these rubble could be appropriated through textile processes to give life to new architectural materials. For example, some fragments were grinded and sieved to achieve the fine grain of a pigment before being mixed with a binder. The ink obtained, charged with the site’s history, was printed on textile using silk screen methods. Bringing together two materials: textile and stone as a mean to reveal the different strata of the site’s story, the outcomes of this process will be the occasion to discuss the potential of conceiving and materialising an architecture informed by its past but also imbued with more suppleness

Influence of membrane-cortex linkers on the extrusion of membrane tubes

The cell membrane is an inhomogeneous system composed of phospholipids, sterols, carbohydrates, and proteins that can be directly attached to underlying cytoskeleton. The protein linkers between the membrane and the cytoskeleton are believed to have a profound effect on the mechanical properties of the cell membrane and its ability to reshape. Here, we investigate the role of membrane-cortex linkers on the extrusion of membrane tubes using computer simulations and experiments. In simulations, we find that the force for tube extrusion has a nonlinear dependence on the density of membrane-cortex attachments: at a range of low and intermediate linker densities, the force is not significantly influenced by the presence of the membrane-cortex attachments and resembles that of the bare membrane. For large concentrations of linkers, however, the force substantially increases compared with the bare membrane. In both cases, the linkers provided membrane tubes with increased stability against coalescence. We then pulled tubes from HEK cells using optical tweezers for varying expression levels of the membrane-cortex attachment protein Ezrin. In line with simulations, we observed that overexpression of Ezrin led to an increased extrusion force, while Ezrin depletion had a negligible effect on the force. Our results shed light on the importance of local protein rearrangements for membrane reshaping at nanoscopic scales

Coordination of Kinesin Motors Pulling on Fluid Membranes

AbstractIntracellular transport relies on the action of motor proteins, which work collectively to either carry small vesicles or pull membranes tubes along cytoskeletal filaments. Although the individual properties of kinesin-1 motors have been extensively studied, little is known on how several motors coordinate their action and spatially organize on the microtubule when pulling on fluid membranes. Here we address these questions by studying, both experimentally and numerically, the growth of membrane tubes pulled by molecular motors. Our in vitro setup allows us to simultaneously control the parameters monitoring tube growth and measure its characteristics. We perform numerical simulations of membrane tube growth, using the experimentally measured values of all parameters, and analyze the growth properties of the tube considering various motor cooperation schemes. The comparison of the numerical results and the experimental data shows that motors use simultaneously several protofilaments of a microtubule to pull a single tube, as motors moving along a single protofilament cannot generate the forces required for tube extraction. In our experimental conditions, we estimate the average number of motors pulling the tube to be approximately nine, distributed over three contiguous protofilaments. Our results also indicate that the motors pulling the tube do not step synchronously

Membrane Shape Modulates Transmembrane Protein Distribution

SummaryAlthough membrane shape varies greatly throughout the cell, the contribution of membrane curvature to transmembrane protein targeting is unknown because of the numerous sorting mechanisms that take place concurrently in cells. To isolate the effect of membrane shape, we used cell-sized giant unilamellar vesicles (GUVs) containing either the potassium channel KvAP or the water channel AQP0 to form membrane nanotubes with controlled radii. Whereas the AQP0 concentrations in flat and curved membranes were indistinguishable, KvAP was enriched in the tubes, with greater enrichment in more highly curved membranes. Fluorescence recovery after photobleaching measurements showed that both proteins could freely diffuse through the neck between the tube and GUV, and the effect of each protein on membrane shape and stiffness was characterized using a thermodynamic sorting model. This study establishes the importance of membrane shape for targeting transmembrane proteins and provides a method for determining the effective shape and flexibility of membrane proteins