Technosolutionnisme

Résumé

vignette|Les énergies renouvelables peuvent apparaître comme une des solutions au réchauffement climatique. Le technosolutionnisme, ou solutionnisme technique, est la confiance dans la technologie pour résoudre un problème souvent créé par des technologies antérieures Selon ce concept, tous les problèmes pourraient trouver des solutions dans des technologies meilleures et nouvelles. Le terme est maintenant utilisé comme une expression condescendante pour décrire des solutions bon marché et rapides en utilisant des technologies inappropriées ; ces correctifs créent souvent plus de problèmes qu'ils n'en résolvent, ou donnent le sentiment qu'ils ont résolu le problème. Certains le définissent comme une « tentative de réparer les dommages causés à une technologie par une modification du système », qui peut impliquer une modification de technologies existantes et/ou une modification de ses procédures d'exploitation ou de maintenance. Les correctifs technologiques sont inévitables dans la

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Les enjeux environnementaux doivent être abordés de façon systémique. L'Analyse du Cycle de Vie (ACV) et l'Analyse de Flux de Matière (AFM) sont des méthodes permettant d'évaluer de façon globale les performances environnementales des produits, des services et des territoires.

Le cours vise à familiariser les étudiants avec l'histoire de l'environnement et des paysages, et avec la façon dont les différentes préoccupations environnementales, qui vont affecter de plus en plus fortement la conception des villes et de l'architecture.

This course gives an introduction to the fundamental concepts and methods of the Digital Humanities, both from a theoretical and applied point of view. The course introduces the Digital Humanities circle of processing and interpretation, from data acquisition to new understandings.

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The perception of pleasantness in many of the consumer goods is provided by volatile chemical compounds called fragrances. While the volatility of fragrances is essential to provide a pleasant olfactory response, it presents at the same time a technological problem, such that their premature evaporation and degradation may occur prior to the application during the storage. Another crucial aspect that affects the performance of the consumer goods is the deposition of these delivery systems to the target of interest. The potential strategies to improve the deposition of fragrance delivery systems are much less explored compared to their preparation and predominantly based on the physiochemical optimization of the surface/interface properties, such as hydrophobicity and charge of the existing delivery systems. However, the extent of depositions achieved using these strategies are typically modest. Phage display is an in vitro evolutionary selection technique that is widely used to identify substrate selective short peptide ligands. Although it has been predominantly used to isolate biomolecule binding ligands, its scope has been expanded in the last decade and it has also found use to identify hard and soft material binders. From this aspect, phage display may also provide short peptide ligands that can bind to i. e. cotton and hair surfaces under laundry and hair wash conditions. These ligands can be considered as a tool to improve the deposition of any fragrance delivery system upon their chemical incorporation via orthogonal functional groups. This Thesis aims to explore the feasibility of phage display identified peptides to selectively deposit fragrance delivery systems on cotton fabric and human hair surfaces and it can be subdivided into 4 Chapters. Chapter 1 provides a summary for the identification and characterization of soft matter binding peptides via phage display. Herein, soft matter will be subdivided into three general classes: synthetic polymers, small organic molecules and natural polymers. Chapter 2 proposes a general synthetic method for the preparation of water soluble peptide-polymer conjugates that proceeds at mild conditions without the requirement of peptide protecting groups. Chapter 3 describes the preparation of fragrance delivery systems that can selectively deposit onto cotton fabric under laundry wash conditions. The Chapter will first show the identification of cotton fabric binding peptides via phage display experiments. In the next steps, the strongest cotton binding peptide will be incorporated into two different model fragrance delivery systems that are based on linear polymers and nanoparticles. Chapter 4 applies the general strategy described in Chapter 3 to a more challenging task: Selectively depositing fragrance delivery systems onto hair under shampoo conditions. First, the feasibility of phage display to identify hair binding peptides under shampoo conditions will be demonstrated. Subsequently, two of the peptide-polymer conjugates described in Chapter 2 will be used as a model for hair targeting fragrance delivery systems. In the final section, the influence of the stringency of the shampoo conditions as well as the steric hindrance in the peptide terminal domains to the deposition of these peptides onto hair will be assessed.

EPFL2016

Chargement

Solid on liquid deposition, a review of technological solutions

Oksana Banakh, Roland Andreas Bitterli, Laure Jeandupeux

Solid-on-liquid deposition (SOLID) techniques are of great interest to the MEMS and NEMS (Micro- and Nano Electro Mechanical Systems) community because of potential applications in biomedical engineering, on-chip liquid trapping, tunable micro-lenses, and replacements of gate oxides. However, depositing solids on liquid with subsequent hermetic sealing is difficult because liquids tend to have a lower density than solids. Furthermore, current systems seen in nature lack thermal, mechanical or chemical stability. Therefore, it is not surprising that liquids are not ubiquitous as functional layers in MEMS and NEMS. However, SOLID techniques have the potential to be harnessed and controlled for such systems because the gravitational force is negligible compared to surface tension, and therefore, the solid molecular precursors that typically condense on a liquid surface will not sediment into the fluid. In this review we summarize recent research into SOLID, where nucleation and subsequent cross-linking of solid precursors results in thin film growth on a liquid substrate. We describe a large variety of thin film deposition techniques such as thermal evaporation, sputtering, plasma enhanced chemical vapor deposition used to coat liquid substrates. Surprisingly, all attempts at deposition to date have been successful and a stable solid layer on a liquid can always be detected. However, all layers grown by non-equilibrium deposition processes showed a strong presence of wrinkles, presumably due to residual stress. In fact, the only example where no stress was observed is the deposition of parylene layers (poly-para-xylylene, PPX). Using all the experimental data analyzed to date we have been able to propose a simple model that predicts that the surface property of liquids at molecular level is influenced by cohesion forces between the liquid molecules. Finally, we conclude that the condensation of precursors from the gas phase is rather the rule and not the exception for SOLID techniques. (C) 2015 The Authors. Published by Elsevier B.V.

Elsevier2015

Chargement

The use of plasmas in aerodynamics has become a recent topic of interest. The potentialities of different types of plasmas are being investigated for low velocity and high velocity flow control, as well as for plasma-assisted combustion. Dielectric barrier discharges (DBDs) are good candidates since the transition of the glow or filamentary discharge to an arc is prevented by the dielectric barrier. Moreover, surface DBDs allow to ionize the gas very close to the dielectric surface and can be used to ionize the boundary layer around an object immersed in a flow. The research in flow control has basically followed two main paths: the study of DBDs in low-speed airflows and the study of volume glow or corona discharges in supersonic airflows. Until today, there has been an important technological barrier in experimental investigations with surface DBDs. Atmospheric pressure surface DBDs in air have been difficult to maintain for long operation times, typically several hours, because reactive species created in the plasma (for example atomic oxygen) generate intensive etching of the electrode and dielectric materials. Oxidation of the electrodes or reduction of the dielectric thickness will eventually lead to plasma extinction or arcing respectively. This important issue has prevented detailed studies of DBDs in extreme environment, namely in high-speed airflows. In the present work, a solution to this technological problem has been found and is presented. Low temperature co-fireable ceramic (LTCC) technology allows, for the first time, to fully encapsulate the electrodes in a ceramic matrix and maximize the lifetime of the DBD system. Encapsulation improves the reproducibility of the experiments. Moreover, the plate can be manufactured in a curved shape. This technological advance permits, in the frame of the research presented here, to carry out a detailed experimental investigation of DBDs in high-speed flows. The goal of this experimental research is to improve the physical understanding of the interaction between a local atmospheric discharge, causing a localized weak ionization of the surrounding airflow, and the shock wave structure in transonic and supersonic flows typical for aeronautic applications. The fundamental nature of the research makes it relevant in a large domain of applications such as sonic boom alleviation, the reduction of aerodynamic losses (drag reduction) or combustion improvement. The surface dielectric barrier discharge is first characterized without airflow in order to understand the influence of the applied electrical conditions and the structure of the DBD plate on the discharge regime its spatial distribution. Current curves and photomultiplier measurements show that the DBD comprises a filamentary and a continuous (glow- or corona-like) component. Increasing the applied voltage ramp (dU2/dt) results in an increase in the filament generation rate and current peak amplitude. The geometry of the electrodes has little effect on the burning voltage but plays a role in the filament generation rate. Encapsulation reduces the rate of filament production and the expansion of the plasma around the upper electrode but it generates a more uniform distribution of the plasma on the surface and as a function of time. The behavior of the surface DBD in a high-speed air flow is first studied in a simple aerodynamic configuration: a flat DBD plate mounted on one wall of the nozzle. It is demonstrated that the DBD generated by this system can be sustained in supersonic airflows up to free stream Mach numbers of M∞=1.1. Current and time-resolved light emission measurements (photomultiplier) show that there are modifications in the discharge regime at high airflow velocity. For overall discharge, the filamentary to continuous component ratio is increased with increasing flow velocities, the plasma becomes relatively more filamentary. For individual microdischarges, the light pulse emission duration is reduced by one order of magnitude. These measurements indicate that there is a change in the breakdown mechanism and it is proposed that a transition from Townsend breakdown to streamer breakdown occurs when the airflow velocity is increased. The inverse problem is then addressed, the effects of the DBD on the airflow, in a case where the plasma is generated on the surface of an airfoil and interacts with the shock structure in the transonic flow field around that airfoil. Although no significant effects of the surface DBD on the normal shock generated in the transonic flow have been observed with the Schlieren visualizations and far-field pressure measurements, the flow modifies the plasma characteristics in a very significant way. In addition to the effects of the flow velocity (as observed in the flat plate experiment), the significant variation of pressure on the surface of the airfoil plays an important role. Decreasing pressure increases the number of filaments and favors high current peak generation. It shows that the discharge characteristics cannot be completely controlled and that they depend on the flow field.

EPFL2008

Chargement

EPFL2016

Solid on liquid deposition, a review of technological solutions

Oksana Banakh, Roland Andreas Bitterli, Laure Jeandupeux

Elsevier2015

EPFL2008