F center in lithium fluoride revisited: Comparison of solid-state physics and quantum-chemistry approaches

in Physical Review. B, Condensed Matter (2014), 89

We revisit the theoretical description of the F color center in lithium fluoride employing advanced complementary ab initio techniques.We compare the results from periodic supercell calculations involving ... [more ▼]

We revisit the theoretical description of the F color center in lithium fluoride employing advanced complementary ab initio techniques.We compare the results from periodic supercell calculations involving density-functional theory (DFT) and post-DFT techniques with those from the embedded-cluster approach involving quantumchemical many-electron wave-function techniques. These alternative approaches yield results in good agreement with each other and with the experimental data provided that correlation effects are properly taken into account. [less ▲]

F-Alloy: a relational model transformation language based on Alloy

in Software and Systems Modeling (2019), 18(1), 213-247

Model transformations are one of the core artifacts of a model-driven engineering approach. The relational logic language Alloy has been used in the past to verify properties of model transformations. In ... [more ▼]

Model transformations are one of the core artifacts of a model-driven engineering approach. The relational logic language Alloy has been used in the past to verify properties of model transformations. In this paper we introduce the concept of functional Alloy modules. In essence a functional Alloy module can be viewed as an Alloy module representing a model transformation. We describe a sublanguage of Alloy called F-Alloy specifically designed to concisely specify functional Alloy modules. The restrictions on F-Alloy’s syntax are meant to allow efficient execution of the specified transformation, without the use of backtracking, by an adapted interpretation algorithm. F-Alloy’s semantics is given in this paper as a direct translation to Alloy; hence, F-Alloy specifications are also analyzable using the powerful automatic analysis features of Alloy. [less ▲]

Fabricating Modern Societies: Education, Bodies and Minds in the Age of Steel

Book published by Brill (2019)

Fabricating Modern Societies: Education, Bodies, and Minds in the Age of Steel, edited by Karin Priem and Frederik Herman, offers new interdisciplinary and transnational perspectives on the history of ... [more ▼]

Fabricating Modern Societies: Education, Bodies, and Minds in the Age of Steel, edited by Karin Priem and Frederik Herman, offers new interdisciplinary and transnational perspectives on the history of industrialization and societal transformation in early-twentieth-century Luxembourg. The individual chapters focus on how industrialists addressed a large array of challenges related to industrialization, borrowing and mixing ideas originating in domains such as corporate identity formation, mediatization, scientification, technological innovation, mechanization, capitalism, mass production, medicalization, educationalization, artistic production, and social utopia, while competing with other interest groups who pursued their own goals. The book looks at different focus areas of modernity, and analyzes how humans created, mediated, and interacted with the technospheres of modern societies. [less ▲]

Fabricating National Unity in Torn Contexts: World War I in the Multilingual Countries of Switzerland and Luxembourg

in Gearóid, Barry; Dal Lago, Enrico; Healy, Róisín (Eds.) Small Nations and Colonial Peripheries in World War I (2016)

Switzerland and Luxembourg are both multilingual countries whose national raison d’être does not refer to one language or culture. During the First World War, both countries experienced inner political ... [more ▼]

Switzerland and Luxembourg are both multilingual countries whose national raison d’être does not refer to one language or culture. During the First World War, both countries experienced inner political conflicts; consequently, the effects of the war on the education of national citizens are of crucial interest. In this article, we analyse teacher journals to highlight the ideas and principles of the 1910s and relate them to the topics of civics, war and peace. In this way, we examine how these two countries interpreted neutrality, shared a commitment to and addressed multilingualism, and sought to educate national citizens. In Switzerland, two major teacher journals immediately reacted to the new circumstance of war with articles and lessons for schools about war and peace, whereas in Luxembourg similar articles appeared only after 1916. Both countries experienced similar discussions about WWI and national unity, peace, and daily difficulties in economic, social and political life. Additionally, some aspects of neutrality were addressed similarly but fostered different aims regarding the military or solidarity. Thus, although the First World War challenged schools – and therefore teachers – and led to different arguments in the two countries on the way that national citizens were to be educated, the proclamations of patriotism, virtues and morals were similar. [less ▲]

La Fabrication Additive Robotisée: Perspective et Recherche autour d'Impression 3D de Pièces Métalliques de Grandes Dimensions pour l'Industrie Aéronautique

Article for general public (2020)

FABRICATION AND INVESTIGATION OF PHYSICOCHEMICAL AND STRUCTURAL GRADIENTS FOR BIOSENSING

Doctoral thesis (2022)

Controlling biomolecule-surface interactions with nano- and micro-engineered surfaces is of great interest in biomedical applications such as tissue regeneration and biosensing platforms. Developing high ... [more ▼]

Controlling biomolecule-surface interactions with nano- and micro-engineered surfaces is of great interest in biomedical applications such as tissue regeneration and biosensing platforms. Developing high-performance functional bio-interfaces for cell-surface or protein-surface interactions necessitates optimizing the interface by modifying material surface variables. Surface gradients are a category of combinatorial technique that enables monitoring and high-throughput optimization of biomolecule-surface interactions by providing a gradually varying surface parameter(s) on a small scale and across an extended area length. It is elaborated that a surface gradient not only greatly reduces the required time and labour of conducting numerous separate experiments for producing several distinct samples but also minimises the inter-batch errors associated with. In this context, multigradients are particularly promising for advanced bio-interface optimisation since they incorporate two or more separate gradients that evolve independently across different directions. While gradients have been vastly studied in past two decades, reporting different surface gradients of chemistry, topography, or mechanical nature in either nano or larger scales, there have been few studies on multigradients, due to the limited operational flexibility required for generating more than one gradient on the surface. First, plasma technologies were explored for establishing a suitable fabricating method for generating spatial variation of surface chemistry along a direction. Both the mask-assisted static and maskless dynamic deposition were examined via two different plasma technologies, namely atmospheric pressure plasma and low-pressure plasma. Depending on the electrical conductivity of the chosen substrates and the nature of the coatings, different surface characterisations were performed on the generated samples. Surface chemistry, surface morphology and wettability properties of the treated surfaces were mainly investigated. As a result, two chemistry gradients were reported; first, an oxygen-functional chemistry gradient deposited with a single-step approach via a programmed corona discharge based on the polymerisation of HMDSO with varying flow rates of oxygen. The chemistry gradient consisted of 7 deposition conditions spanning between mostly organic and inorganic coating also exhibiting the surface energy gradient along a polyethylene foil with length of 10 cm. The surface morphology was also altered as oxygen level was increasing, leading to mild gradual surface roughening. Second, a nitrogen-functional chemistry gradient with the specific feature of enhanced water stability was reported via polymerisation of ethylene with gradually varying ammonia flow rates using a mask-assisted static deposition approach with low pressure capacitively coupled radio frequency plasmas. A smooth coating exhibiting a chemistry gradient consisted of four deposition conditions, and a subsequent surface energy gradient was achieved along 1 cm width of a 2x1cm Si chip. Following that, a versatile experimental setup was presented for developing the next class of surface gradients, the structural or topography gradients, which benefited from a rational design and soft lithography. As a result, a total of 4 topography gradients were reported, two of which were stochastic density gradients and the other two being periodical nanocluster density and periodical size gradients. The gradient was formed based on time-dependent incubation of the functionalised material surface with the chosen precursor and electrostatic interactions between the two. The main experimental inputs were the precursor flow rate, dimension of the experiment chamber and dimension of the substrate. For material surface functionalisation, various classes of chemistries were employed, including aminosilane monolayers, cross-linked plasma polymer, and copolymer templates for developing either stochastic or periodic arrangements of the surface features. The kinetics of incubation of each functional surface was monitored with real-time QCM before gradient formation allowing a prediction of surface coverage and all the generated gradients were investigated for their surface morphology. The obtained micrographs and the respective experimental plots and theoretical fittings confirmed the successful formation of stochastic and periodical topography gradients. Surface-enhanced Raman spectroscopy (SERS) studies revealed the high potential of gold nanocluster density gradients for SERS-based biosensing applications. However, despite exceptionally strong SERS signals recorded on the nanoparticle density gradient (generated on the plasma polymer template), the SERS response diminished at some spots along the surface, revealing a noncontinuous SERS variation. Meanwhile, gold domes did not demonstrate any enhancement as a function of size variation. Wettability analyses were performed selectively on the stochastic gold nanoparticle density gradient utilizing both the experimental sessile drop method and theoretical modelling to investigate the probable wetting regime. The theoretical modelling indicated good agreement with the experimental WCAs and indicated Wenzel, full wetting regime.As the ultimate objective, an orthogonal surface gradient was presented. The approach was based on depositing the previously reported nitrogen-functional chemistry gradient in a perpendicular direction over the unidirectional stochastic gold nanoparticle density gradient. As confirmed by XPS and ToF-SIMS, the surface chemical composition was retained after coating and did not change due to the presence of the underlying conductive gold nanoparticle layer. The surface morphology was significantly altered after being coated with the top plasma layer, demonstrating an overall decreased roughness variation compared to the unidirectional nanoparticle density gradient. Furthermore, the surface wettability variation was significantly lower when compared to the wettability variation scale of the integrated unidirectional gradients. [less ▲]

Fabrication and performance of AlGaN/GaN HEMTs on (111) Si substrates

in Physica Status Solidi A. Applications and Materials Science (2002), 194(2), 472-475

In the current work the performance of AlGaN/GaN HEMTs fabricated on silicon substrates is presented. The AlGaN/GaN material structures were grown on (111) Si by MOVPE. Static I–V characteristics with a ... [more ▼]

In the current work the performance of AlGaN/GaN HEMTs fabricated on silicon substrates is presented. The AlGaN/GaN material structures were grown on (111) Si by MOVPE. Static I–V characteristics with a saturation current of 0.91 A/mm and a peak extrinsic transconductance of 122 mS/mm were measured and show minimal thermal effects. For devices with a gate length of 0.7 um and 0.5 um, a unity gain frequency of 20 GHz and 32 GHz and a maximum frequency of oscillation of 22 GHz and 27 GHz, respectively were obtained. The unity gain frequencies are the highest values reported so far on AlGaN/GaN/Si HEMTs and fully comparable to those known for devices using sapphire and SiC substrates. However, the fmax to fT ratio is only about 1, which indicates on parasitic conduction through the Si substrate under small signal conditions. It is shown that the saturation current and the transconductance decrease much less with increased temperature than known for similar devices grown on sapphire. [less ▲]

Fabrication of Laterally Displaced Porous Silicon Filters

in Thin Solid Films (2001), 382(2001), 218-221

Porous silicon superlattices have been used to manufacture laterally displaced dielectric filters with different optical properties on one substrate. Two different fabrication processes for two-colour ... [more ▼]

Porous silicon superlattices have been used to manufacture laterally displaced dielectric filters with different optical properties on one substrate. Two different fabrication processes for two-colour microfilter arrays are presented. Both methods overcome the problem of non-uniform optical properties of the well-known procedure where two filter stacks are grown one upon another, with subsequent partial removal of the upper filter by reactive ion etching. The novel methods give uniform optical properties of the two filter areas, profiting from the main property of the formation process of porous silicon: the formation of porous silicon occurs only at the porous silicon substrate interface. [less ▲]

Fabrication of Si tunnel diodes for c-Si based tandem solar cells using proximity rapid thermal diffusion

in Energy Procedia (2017), 124

Increasing competitiveness of photovoltaic (PV) devices is currently an important objective in technological research, especially with the development of tandem solar cells based on c-Si as the bottom ... [more ▼]

Increasing competitiveness of photovoltaic (PV) devices is currently an important objective in technological research, especially with the development of tandem solar cells based on c-Si as the bottom cell. For a monolithical structure, a tunnel diode in between the top and bottom cells is necessary. In this work we report on the development of the fabrication of Si tunnel junction using a combination of spin-on doping and proximity rapid thermal diffusion. A desirable attribute of this process is simplicity. Two different structures p++/n++ or n++/p++ were fabricated on (100) Si substrates. Carrier density profiles were measured by ECV to characterize the shallow doping profiles. Vertical tunnel diodes were fabricated and I(V) characteristics are presented. It is shown that device peak current densities up to 270 A/cm² are achieved using this technique, which is the best value reported with such simple technique. [less ▲]

Fabriquer du « bien-être » : tension entre missions chez les personnels d’Etablissements d’Hébergement pour Personnes Âgées Dépendantes (EHPAD) en France

in Nouvelles Pratiques Sociales (2011), 24(Automne), 178

Les institutions d’hébergement pour personnes âgées d’aujourd’hui, en France, rejoignent deux objectifs : celui de faire habiter, et celui de soigner. La rencontre entre ces deux dialectiques offre à ... [more ▼]

Les institutions d’hébergement pour personnes âgées d’aujourd’hui, en France, rejoignent deux objectifs : celui de faire habiter, et celui de soigner. La rencontre entre ces deux dialectiques offre à l’observateur les logiques à l’œuvre dans ces institutions, différentes selon les situations. Trois systèmes co-existants de références y hiérarchisent chacun à sa manière les individus et les objets. Au sein de la « cité marchande », de la « cité industrielle » et de la « cité domestique », les résidents n’occupent pas la même place, et les interactions gagnent à être comprises dans l’entremêlement complexe de ces systèmes de références qui agissent l’institution. [less ▲]