Seminar as a way to educate engineering students on environmental challenges in the textile industry

The Ecole Nationale Supérieure des Arts et Industries Textiles (ENSAIT) is one of the few schools specialising in materials for the textile industry. Each year it graduates around 110 engineers whose role is to meet the challenges of the sector while respecting the values of the companies and environmental standards. The ENSAIT engineer's course takes place over three years. From the first year of the engineering cycle, a seminar on sustainable development is offered. It is held in the second semester and lasts two full days. The first objective is to make them aware of corporate social responsibility (CSR) issues in companies. The second is to build on the knowledge acquired during the last 6 months to develop the life cycle of a garment and understand the associated impacts. Finally, it is to highlight the different possible strategies based on eco-design, fair trade, taking into account the regulatory constraints. This seminar is based on active pedagogy, where students work in teams and compare their results with each other. It also aims to provide the minimum tools to understand ecodesign strategies and to be an informed fashion consumer, and to become a textile engineer capable of participating in and technically supporting companies' CSR initiatives

A Modular Surrogate-assisted Framework for Expensive Multiobjective Combinatorial Optimization

The aim of this paper is to push a step towards the development of a surrogate-assisted methodology for expensive optimization problems that have both a combinatorial and a multiobjective nature. We target pseudo-boolean multiobjective functions, and we provide a comprehensive study on the design of a modular framework integrating three main configurable components. The proposed framework is based on the Walsh basis as a surrogate, and on a decomposition-based evolutionary paradigm for maintaining the solution set. The three considered components are: (i) the inner optimizer used for handling the soconstructed Walsh surrogate, (ii) the selection strategy allowing to decide which solution is to be evaluated by the expensive objectives, and (iii) the strategy used to setup the Walsh order hyper-parameter. Based on a thorough empirical analysis relying on two benchmark problems, namely bi-objective NK-landscapes and UBQP problems, we show the effectiveness of the proposed framework with respect to the available budget in terms of calls to the evaluation function. More importantly, our empirical findings shed more lights on the combined effects of the investigated components on search performance, thus providing a better understanding of the key challenges for designing a successful surrogate-assisted multiobjective combinatorial search process

Surrogate-assisted Multi-objective Combinatorial Optimization based on Decomposition and Walsh Basis

International audienceWe consider the design and analysis of surrogate-assisted algorithms for expensive multi-objective combinatorial optimization. Focusing on pseudo-boolean functions, we leverage existing techniques based on Walsh basis to operate under the decomposition framework of MOEA/D. We investigate two design components for the cheap generation of a promising pool of offspring and the actual selection of one solution for expensive evaluation. We propose different variants, ranging from a filtering approach that selects the most promising solution at each iteration by using the constructed Walsh surrogates to discriminate between a pool of offspring generated by variation, to a substitution approach that selects a solution to evaluate by optimizing the Walsh surrogates in a multi-objective manner. Considering bi-objective NK landscapes as benchmark problems offering different degree of non-linearity, we conduct a comprehensive empirical analysis including the properties of the achievable approximation sets, the anytime performance, and the impact of the order used to train the Walsh surrogates. Our empirical findings show that, although our surrogate-assisted design is effective, the optimal integration of Walsh models within a multi-objective evolutionary search process gives rise to particular questions for which different trade-off answers can be obtained

Filterability of exopolysaccharides solutions from the red microalga Porphyridium cruentum by tangential filtration on a polymeric membrane

International audienceThe red microalga Porphyridium cruentum is exploited industrially for its exopolysaccharides (EPS) and pigments production. EPS produced by P. cruentum are partially released and dissolved into the surrounding environment, they can be recovered from the culture medium after removing the cells. This paper presents a parametric study of the ultrafiltration of EPS solutions on organic membrane. The EPS solutions were produced in conditions representative of an industrial production. They were filtered at lab-scale on a flat, PES 50 kDa MWCO membrane in a complete recirculation mode of permeate and retentate. Permeate flux-transmembrane pressure (TMP) curves were established up to the limiting flux for the filtration of solutions with various values of concentration in EPS (0.10 to 1.06 kg GlcEq.m), fluid tangential velocity (0.3 to 1.2 m.s) and temperature (20 and 40 °C). The reversible and irreversible parts of fouling were evaluated for each experiment and the critical flux was determined for an intermediate EPS concentration (0.16 kg GlcEq.m). The results showed that EPS solutions had a strong fouling capacity. When filtering the lowest concentrated solution (0.10 kg GlcEq.m) with moderate fouling conditions, the overall fouling resistance was approximately half of the membrane and the share of irreversible/reversible fouling was 88 and 12%. However, the part of reversible fouling becomes predominant when approaching the limiting flux. Permeate fluxes which were obtained allow to estimate that a VRR of approximately 10 could be obtained when concentrating EPS solutions using PES membranes in flat or tubular modules but not in spiral-wound

Genome sequencing of Xanthomonas axonopodis pv. phaseoli CFBP4834-R reveals that flagellar motility is not a general feature of xanthomonads.

Xanthomonads are plant-associated bacteria that establish neutral, commensal or pathogenic relationships with plants. The list of common characteristics shared by all members of the genus Xanthomonas is now well established based on the entire genome sequences that are currently available and that represent various species, numerous pathovars of X. axonopodis (sensu Vauterin et al., 2000), X. oryzae and X. campestris, and many strains within some pathovars. These ?-proteobacteria are motile by a single polar flagellum. Motility is an important feature involved in biofilm formation, plant colonization and hence considered as a pathogenicity factor. X. axonopodis pv. phaseoli var. fuscans (Xapf) is one of the causal agents of common bacterial blight of bean and 4834-R is a highly aggressive strain of this pathogen that was isolated from a seed-borne epidemic in France in 1998. We obtained a high quality assembled sequence of the genome of this strain with 454-Solexa and 2X Sanger sequencing. Housekeeping functions are conserved in this genome that shares core characteristics with genomes of other xanthomonads: the six secretion systems which have been described so far in Gram negative bacteria are all present, as well as their ubiquitous substrates or effectors and a rather usual number of mobile elements. Elements devoted to the adaptation to the environment constitute an important part of the genome with a chemotaxis island and dispersed MCPs, numerous two-component systems, and numerous TonB dependent transporters. Furthermore, numerous multidrug efflux systems and functions dedicated to biofilm formation that confer resistance to stresses are also present. An intriguing feature revealed by genome analysis is a long deletion of 35 genes (33 kbp) involved in flagellar biosynthesis. This deletion is replaced by an insertion sequence called ISXapf2. Genes such as flgB to flgL and fliC to fleQ which are involved in the flagellar structure (rod, P- and L-ring, hook, cap and filament) are absent in the genome of strain 4834-R that is not motile. Primers were designed to detect this deletion by PCR in a collection of more than 300 strains representing different species and pathovars of Xanthomonas, and less than 5% of the tested xanthomonads strains were found nonmotile because of a deletion in the flagellum gene cluster. We observed that half of the Xapf strains isolated from the same epidemic than strain 4834-R was non-motile and that this ratio was conserved in the strains colonizing the next bean seed generation. Isolation of such variants in a natural epidemic reveals that either flagellar motility is not a key function for fitness or that some complementation occurs within the bacterial population. (Résumé d'auteur

Genome sequence of Xanthomonas fuscans subsp. fuscans strain 4834-R reveals that flagellar motility is not a general feature of xanthomonads

Abstract\ud \ud \ud \ud Background\ud Xanthomonads are plant-associated bacteria responsible for diseases on economically important crops. Xanthomonas fuscans subsp. fuscans (Xff) is one of the causal agents of common bacterial blight of bean. In this study, the complete genome sequence of strain Xff 4834-R was determined and compared to other Xanthomonas genome sequences.\ud \ud \ud \ud Results\ud Comparative genomics analyses revealed core characteristics shared between Xff 4834-R and other xanthomonads including chemotaxis elements, two-component systems, TonB-dependent transporters, secretion systems (from T1SS to T6SS) and multiple effectors. For instance a repertoire of 29 Type 3 Effectors (T3Es) with two Transcription Activator-Like Effectors was predicted. Mobile elements were associated with major modifications in the genome structure and gene content in comparison to other Xanthomonas genomes. Notably, a deletion of 33 kbp affects flagellum biosynthesis in Xff 4834-R. The presence of a complete flagellar cluster was assessed in a collection of more than 300 strains representing different species and pathovars of Xanthomonas. Five percent of the tested strains presented a deletion in the flagellar cluster and were non-motile. Moreover, half of the Xff strains isolated from the same epidemic than 4834-R was non-motile and this ratio was conserved in the strains colonizing the next bean seed generations.\ud \ud \ud \ud Conclusions\ud This work describes the first genome of a Xanthomonas strain pathogenic on bean and reports the existence of non-motile xanthomonads belonging to different species and pathovars. Isolation of such Xff variants from a natural epidemic may suggest that flagellar motility is not a key function for in planta fitness.AI is funded by a PhD grant from INRA-SPE and region Pays de la Loire, France. EG was funded by a PhD grant from the French Ministry of National Education and Research and French Guyana. SC, EG, MA, EL and LDN are funded by the LABEX TULIP (ANR-10-LABX-41), LSG is funded by ANR-2010-GENM-013 Xanthomix

Origin and mobility of Iron Age Gaulish groups in present-day France revealed through archaeogenomics

The Iron Age period occupies an important place in French history, as the Gauls are regularly presented as the direct ancestors of the extant French population. We documented here the genomic diversity of Iron Age communities originating from six French regions. The 49 acquired genomes permitted us to highlight an absence of discontinuity between Bronze Age and Iron Age groups in France, lending support to a cultural transition linked to progressive local economic changes rather than to a massive influx of allochthone groups. Genomic analyses revealed strong genetic homogeneity among the regional groups associated with distinct archaeological cultures. This genomic homogenisation appears to be linked to individuals’ mobility between regions as well as gene flow with neighbouring groups from England and Spain. Thus, the results globally support a common genomic legacy for the Iron Age population of modern-day France that could be linked to recurrent gene flow between culturally differentiated communities