Characterization of ultrafiltration membranes by tracer's retention:Comparison of methods sensitivity and reproducibility

Previous studies have shown that the absolute membrane cut-off and the value quoted by the manufacturers may be very different because of differences in methodologies and testing conditions. The origin of this discrepancy is often difficult to identify as the characterization method used by the membrane manufacturers is not specified. The goal of this study is to evaluate in terms of sensitivity, repeatability and reproducibility the methodologies used by a working group including membrane manufacturers, end-users and a research laboratory. The five selected membranes are hollow fibers used in drinking water production. They are made of various materials with different configurations (internal–external and external–internal type) and molecular weight cut-offs. Different types of tracers are used: dextrans, poly (ethylene glycol)s, poly(ethylene oxide)s, MS2 bacteriophage filtrated in single sized solution or in mixture. Results collected lead to a better understanding of the origin of discrepancies and allow to define the best operating conditions (tracer's type, working conditions range, data treatment methods,…) providing the most appropriate, accurate and reproducible testing protocol according to the selected application

A Problemática da tradução no curso de Línguas e Secretariado do ISCAP

Polissema: Revista de Letras do ISCAP 2001/N.º 1 - TraduçãoO curso de Línguas e Secretariado que abarca, na primeira etapa da Licenciatura, as duas vertentes, divide-se em dois ramos, na segunda; neste prolongamento temos, por um lado, a tradução especializada para a área das línguas e, por outro, o secretariado de gestão na área do secretariado. Logicamente, a opção entre estas duas hipóteses é feita pelos próprios alunos, mas de acordo com as aptidões e capacidades demonstradas durante a primeira etapa do curso. No nosso caso, como somos professoras de Língua Materna e estrangeira (francês), debruçar-nosemos sobre a problemática do ensino das línguas e, logo, da tradução em termos gerais para, de seguida, abordarmos a tradução especializada

Room temperature electronic template effect of pre-structured SmSi(111)-8x2 interface yielding self-aligned organic molecules

International audienceThis work describes an innovative concept for the development of organized molecular systems thanks to the template effect of the pre-structured semi-conductive SmSi(111) interface. This substrate was selected because Sm deposition in the submonolayer range leads to a 8x2-reconstruction, which is a well-defined one-dimensional semi-metallic structure. Adsorption of aromatic molecules (1,4-di-(9-ethynyltriptycenyl)-benzene) on SmSi(111)-8x2 and Si(111)-7x7 interfaces has been investigated by scanning tunneling microscopy (STM) at room temperature. Density functional theory (DFT) and semi-empirical (ASED+) calculations have been performed to define the nature of the molecular adsorption sites of the target molecule on SmSi as well as their self-alignment on this interface. Experimental data and theoretical results are in good agreement

Paramagnetic gold in a highly disordered Au-Ni-O alloy

Magnetic materials are usually classified into a distinct category such as diamagnets, paramagnets or ferromagnets. The enormous progress in materials science allows one nowadays, however, to change the magnetic nature of an element in a material. Gold, in bulk form, is traditionally a diamagnet. But in a ferromagnetic environment, it can adopt an induced ferromagnetic moment. Moreover, the growth of gold under certain conditions may lead to a spontaneous ferromagnetic or paramagnetic response. Here, we report on paramagnetic gold in a highly disordered Au–Ni–O alloy and focus on the unusual magnetic response. Such materials are mainly considered for plasmonic applications. Thin films containing Au, Ni and NiO are fabricated by co-deposition of Ni and Au in a medium vacuum of 2 × 10−2 mbar. As a result, Au is in a fully disordered state forming in some cases isolated nanocrystallites of up to 4 nm in diameter as revealed by high resolution transmission electron microscopy. The disorder and the environment, which is rich in oxygen, lead to remarkable magnetic properties of Au: an induced ferromagnetic and a paramagnetic state. This can be proven by measuring the x-ray magnetic circular dichroism. Our experiments show a way to establish and monitor Au paramagnetism in alloys

HRTEM observations of La2Zr2O7 thin layers on LaAlO3 obtained by chemical methods

11 pagesInternational audienceLa2Zr2O7 (LZO) films have been grown by metalorganic Decomposition (MOD) to be used as buffer layers for coated conductors. LZO can crystallize into two similarstructures: fluorite or pyrochlore. Coated conductor application focuses on pyrochlore structure because it is a good barrier against oxygen diffusion. Classical X-ray diffraction is not able to separate the contribution of these two structures. TEM and HRTEM were used to determine the local distribution of these two phases in epitaxial LZO layers grown on LaAlO3. A characteristic feature of LZO thin films deposited by MOD is the formation of nanovoids in an almost single crystal structure of LZO pyrochlore phase. Forcomparison, LZO layers deposited by Metalorganic Chemical Vapor Deposition (MOCVD) were also studied. In this last case, the film is compact without voids and thestructure corresponds to pyrochlore phase. Thus, the formation of nanovoids is a characteristic feature of MOD grown films

Sensations et retrouvailles avec la nature dans le conte romantique

Sous l'influence de penseurs comme Schelling, Novalis, Tieck et Nodier puis George Sand renouent avec une vision panthéiste du monde et avec une intensité de la sensation que leurs contemporains paraissent avoir perdue. Ils refusent l'appauvrissement de l'imaginaire tout comme la séparation de l'homme avec la nature, liés selon eux aux progrès de la technique ainsi qu'au culte de la raison et de l'utile. Ils s'emparent du conte pour le mettre au service d'une exploration universelle au sein de laquelle le personnage est soumis à des expériences qui le mettent en contact avec les différents règnes de la nature, le monde regagnant dans leur œuvre en sensorialité ce qu'il avait perdu en réalité.Under the influence of thinkers such as Schelling, Novalis, the authors Tieck and Nodier then G. Sand get back in touch with a pantheistic vision of the world, and with an intensity of feeling that their contemporaries seem to have lost. They refuse the impoverishment of the imaginary, as well as the separation between men and nature, linked—according to them—to technical progress as well as to the cult of Reason and of Usefulness. They adapt the tale and use it as a universal exploration in which the character is submitted to experiences that put him in contact with the different aspects of nature, the world regaining in sensoriality, in their work, what it had actually lost

A multi-dimensional version of Lamperti's relation and the Matsumoto-Yor processes

This paper presents a multidimensional extension of the Matsumoto-Yor properties related to exponential functionals of drifted Brownian motion. The extension involves the interaction of geometric Brownian motions which are indexed by the vertices of a finite weighted graph, and the random potential associated with the Vertex Reinforced Jump process on this graph. We prove in this context a counterpart of Lamperti's transformation, of the Markov property of the Matsumoto-Yor process and of the intertwining relation.Comment: Extended version of arXiv:2004.10692 with a new author Keywords: exponential functional of Brownian motion, Inverse Gaussian law, vertex reinforced jump process, Pitman 2M-B theorem, Pitman transfor

Phase transition in the Integrated Density of States of the Anderson model arising from a supersymmetric sigma model

We study the Integrated Density of States (IDS) of the random Schr\"odinger operator appearing in the study of certain reinforced random processes in connection with a supersymmetric sigma-model. We rely on previous results on the supersymmetric sigma-model to obtain lower and upper bounds on the asymptotic behavior of the IDS near the bottom of the spectrum in all dimension. We show a phase transition for the IDS between weak and strong disorder regime in dimension larger or equal to three, that follows from a phase transition in the corresponding random process and supersymmetric sigma-model. In particular, we show that the IDS does not exhibit Lifshitz tails in the strong disorder regime, confirming a recent conjecture. This is in stark contrast with other disordered systems, like the Anderson model. A Wegner type estimate is also derived, giving an upper bound on the IDS and showing the regularity of the function.Comment: 44 pages, revised version: improved exposition and corrected typo

XAFS atomistic insight of the oxygen gettering in Ti/HfO2 based OxRRAM

Hafnia-based resistive memories technology has come to maturation and acceded to the market of nonvolatile memories. Nevertheless, the physical mechanisms involved in resistive switching are not yet fully understood and the numerous ab initio simulations studies have few many atomic-scale experimental counterparts. In this study we investigate the oxygen migration mechanism from an amorphous HfO2 layer to the Ti cap layer at a local scale before and after a thermal treatment. X-ray absorption spectroscopy at the Ti K edge and Hf L(III )edge has been performed on samples as-deposited and annealed in Ar at 400 degrees C to mimic the back-end-of-line thermal budget (BEOL) of CMOS technology. The short-range Ti and Hf environments have been determined, showing that annealing promotes the migration of O from HfO2 to Ti, the amount of which is quantified. This provokes an expansion and an increase of atomic disorder in the Ti lattice. The nature of the oxygen gettering mechanism by the Ti metal is understood by comparing samples with increasing Ti-capping thickness. We show that the Ti getter effect has to be activated by thermal treatment and that the O diffusion takes place in a region of a few nanometers close to the Ti/HfO2 interface. Therefore, the thermal budget history and the Ti cap-layer thickness determine the oxygen vacancy content in the HfO2 layer, which in turn controls the electrical properties, especially the forming operation