École Nationale Supérieure de Chimie de Lille

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Furfural and 5-hydroxymethylfurfural stand out as bridges connecting biomass raw materials to the biorefinery industry. Their reductive transformations by hydroconversion are key routes toward a wide variety of chemicals and biofuels, and heterogeneous catalysis plays a central role in these reactions. The catalyst efficiency highly depends on the nature of metals, supports, and additives, on the catalyst preparation procedure, and obviously on reaction conditions to which catalyst and reactants are exposed: solvent, pressure, and temperature. The present review focuses on the roles played by the catalyst at the molecular level in the hydroconversion of furfural and 5-hydroxymethylfurfural in the gas or liquid phases, including catalytic hydrogen transfer routes and electro/photoreduction, into oxygenates or hydrocarbons (e.g., furfuryl alcohol, 2,5-bis(hydroxymethyl)furan, cyclopentanone, 1,5-pentanediol, 2-methylfuran, 2,5-dimethylfuran, furan, furfuryl ethers, etc.). The mechanism of adsorption of the reactant and the mechanism of the reaction of hydroconversion are correlated to the specificities of each active metal, both noble (Pt, Pd, Ru, Au, Rh, and Ir) and non-noble (Ni, Cu, Co, Mo, and Fe), with an emphasis on the role of the support and of additives on catalytic performances (conversion, yield, and stability). The reusability of catalytic systems (deactivation mechanism, protection, and regeneration methods) is also discussed.

The green lineage is reportedly 1,500 million years old, evolving shortly after the endosymbiosis event that gave rise to early photosynthetic eukaryotes. In this study, we unveil the complete genome sequence of an ancient member of this lineage, the unicellular green alga Ostreococcus tauri (Prasinophyceae). This cosmopolitan marine primary producer is the world's smallest free-living eukaryote known to date. Features likely reflecting optimization of environmentally relevant pathways, including resource acquisition, unusual photosynthesis apparatus, and genes potentially involved in C(4) photosynthesis, were observed, as was downsizing of many gene families. Overall, the 12.56-Mb nuclear genome has an extremely high gene density, in part because of extensive reduction of intergenic regions and other forms of compaction such as gene fusion. However, the genome is structurally complex. It exhibits previously unobserved levels of heterogeneity for a eukaryote. Two chromosomes differ structurally from the other eighteen. Both have a significantly biased G+C content, and, remarkably, they contain the majority of transposable elements. Many chromosome 2 genes also have unique codon usage and splicing, but phylogenetic analysis and composition do not support alien gene origin. In contrast, most chromosome 19 genes show no similarity to green lineage genes and a large number of them are specialized in cell surface processes. Taken together, the complete genome sequence, unusual features, and downsized gene families, make O. tauri an ideal model system for research on eukaryotic genome evolution, including chromosome specialization and green lineage ancestry.

Glycopeptides and oligosaccharides of either the N ‐acetyllactosaminic or the oligomannosidic type derived from glycoproteins containing the N ‐glycosylamine linkage were used to define the specificity of different lectins (concanavalin A, Lens culinaris agglutinin, Vicia faba agglutinin, Pisum sativum agglutinin, Ricinus communis agglutinins, soybean agglutinin, wheat germ agglutinin, Solanum tuberosum agglutinin, Datura stramonium agglutinin, Lotus tetragonolobus agglutinin, Ulex europeus agglutinin) by studying the inhibition of human red blood cell agglutination by these structures. The results obtained show that lectins considered ‘identical’ in terms of monosaccharide specificity, possess the ability to recognize fine differences in more complex structures. In fact, different lectins are able to recognize different saccharidic sequences on the same glycan structure. As these sequences are likely to be common to numerous glycoproteins, including cell membrane glycoproteins, the results obtained with lectins in the study of cell surface carbohydrates have to be very carefully interpreted. Moreover, our results confirm previous data on the spatial configuration of the glycan moiety of glycoproteins deduced from the construction of molecular models; the fact that oligosaccharides bearing an α‐NeuAc‐(2→6)‐Gal unit are more powerful inhibitors than oligosaccharides bearing an α‐NeuAc‐(2→3)‐Gal unit could be related to the high rotational freedom of α‐2, 6 linkage; the observation that glycoasparagines, glycopeptides and glycoproteins possess a higher affinity for lectins than the related oligosaccharides could be explained by the fact that the glycan‐amino acid linkage leads to structures more rigid than those of the oligosaccharides themselves.

Abstract Summary: This paper reviews recent approaches for making intumescent systems. The mechanisms of action involving intumescence are described and commented on. Synergistic aspects using zeolites and organoclays are also considered and discussed. New strategies are examined on the basis of the mechanism of intumescence. The approach of using char forming polymers as additives (blend technology) is also fully discussed. This consists of substituting classical polyols (char forming agents) with char forming polymers (polyamides and thermoplastic polyurethane). It will be shown that the advantages of this concept are to obtain flame‐retarded (FR) polymer blends with improved mechanical properties in comparison with polymers loaded with classical formulations, and the avoidance of problems due to the water solubility of the polyols and their migration. The “nanocomposite approach” enhances the performance of intumescent systems by using a nanostructured char forming polymer. It will be shown that this combination of intumescence via the blending approach and nanocomposites enhances both flame retardancy and mechanical properties, and allows many specifications to be produced (for example, the design of EVA‐based materials for flame retarded low voltage cables and wire). This appears to be one of the most promising ways for designing new efficient intumescent materials. Intumescent residue after LOI test of an intumescent poly(propylene). magnified image Intumescent residue after LOI test of an intumescent poly(propylene).

In this Feature Article, we discuss recent developments of flame retardant polymers. Three approaches are considered: (i) inherently flame retardant polymers, (ii) chemically modified polymers and (iii) flame retardants as additives for polymers. We have tried to show the new directions and concepts emerging in the field of flame retardancy. We have mainly focused our comments on flame retardants, nanofillers and surface treatment because very promising concepts appeared recently in the published literature. Synergistic aspects are also fully discussed.

), a calcium phosphate biomaterial, is a very promising candidate for the treatment of air, water and soil pollution. Indeed, hydroxyapatite (Hap) can be extremely useful in the field of environmental management, due in one part to its particular structure and attractive properties, such as its great adsorption capacities, its acid-base adjustability, its ion-exchange capability and its good thermal stability. Moreover, Hap is able to constitute a valuable resource recovery route. The first part of this review will be dedicated towards presenting Hap's structure and defining properties that result in its viability as an environmental remediation material. The second will focus on its use as adsorbent for wastewater and soil treatment, while indicating the mechanisms involved in this remediation process. Finally, the last part will impart all findings on Hap's applications in the field of catalysis, whether it be as catalyst, as photocatalyst, or as active phase support. Hence, all of the above will have served in showcasing the benefits gained by employing hydroxyapatite in air, water and soil clean-up.

The complete amino acid sequence (703 amino acid residues) of human lactotransferrin has been determined. The location of the disulfide bridges has also been investigated. Computer analysis established internal homology of the two domains (residues 1-338 and residues 339-703). Each domain contains a single iron-binding site and a single glycosylation site (asparagine residues 137 and 490) located in homologous positions. Prediction of the secondary structure of the two homologous moieties of human lactotransferrin has also been performed. The present results allowed a series of comparisons to be made with human serum transferrin and hen ovotransferrin.

Over the past decade, many efforts have been made to develop new materials exhibiting high oxide ion mobility at low temperature. In addition to the improvements of existing materials, new classes of conductors in which the structure have been shown to play an important role has been proposed. These materials are reviewed according to their structure type. Their performances and limitations are presented and discussed.

Lignin-derived flame retardants represent one of the most promising directions for next-generation flame retardants due to their sustainability, environmental benefits and comparable efficiency to current non-bio-based counterparts.

The behavior of carbon and nitrogen atoms in iron based solid solution is studied by ab initio density-functional-theory calculations. The interaction of a C or a N atom in $\ensuremath{\alpha}$-Fe with a vacancy, other C or N interstitials as well as self-interstitial atoms is discussed and compared to known experimental results. The migration of these two foreign interstitial atoms is determined in pure Fe or when a vacancy is present in the supercell. According to our results, there is a strong binding energy of C or N with vacancies, whereas a repulsion is observed with self-interstitial atoms. Furthermore, a vacancy can trap up to two C, and a covalent bonding forms between the two C atoms. The situation is not as clear for N atoms, and a competition between the formation of N-V pairs and NN-V triplets is very probable.

International audience

Many polycyclic aromatic hydrocarbons are able to trap singlet oxygen (1)O(2). Some of the endoperoxides, thus obtained, exhibit the exceptional feature of releasing oxygen, frequently in the excited singlet state, under heating or UV irradiation. In this Account, we provide a short summary of the present knowledge on these endoperoxides: preparation and thermal and photolytic decomposition, with a special emphasis on the structural requirements to favor cycloreversion. The profitable use of this property in the development of highly reversible photochromic systems and of specific sources or traps of (1)O(2) in aqueous media is also described.

Over the last few years, extraordinary advances in experimental and theoretical tools have allowed us to monitor and control matter at short time and atomic scales with a high degree of precision. An appealing and challenging route toward engineering materials with tailored properties is to find ways to design or selectively manipulate materials, especially at the quantum level. To this end, having a state-of-the-art ab initio computer simulation tool that enables a reliable and accurate simulation of light-induced changes in the physical and chemical properties of complex systems is of utmost importance. The first principles real-space-based Octopus project was born with that idea in mind, i.e., to provide a unique framework that allows us to describe non-equilibrium phenomena in molecular complexes, low dimensional materials, and extended systems by accounting for electronic, ionic, and photon quantum mechanical effects within a generalized time-dependent density functional theory. This article aims to present the new features that have been implemented over the last few years, including technical developments related to performance and massive parallelism. We also describe the major theoretical developments to address ultrafast light-driven processes, such as the new theoretical framework of quantum electrodynamics density-functional formalism for the description of novel light-matter hybrid states. Those advances, and others being released soon as part of the Octopus package, will allow the scientific community to simulate and characterize spatial and time-resolved spectroscopies, ultrafast phenomena in molecules and materials, and new emergent states of matter (quantum electrodynamical-materials).

Fischer-Tropsch synthesis (FTS) is an essential approach to convert coal, biomass, and shale gas into fuels and chemicals, such as lower olefins, gasoline, diesel, and so on. In recent years, there has been increasing motivation to deploy FTS at commercial scales which has been boosting the discovery of high performance catalysts. In particular, the importance of support in modulating the activity of metals has been recognized and carbonaceous materials have attracted attention as supports for FTS. In this review, we summarised the substantial progress in the preparation of carbon-based catalysts for FTS by applying activated carbon (AC), carbon nanotubes (CNTs), carbon nanofibers (CNFs), carbon spheres (CSs), and metal-organic frameworks (MOFs) derived carbonaceous materials as supports. A general assessment of carbon-based catalysts for FTS, concerning the support and metal properties, activity and products selectivity, and their interactions is systematically discussed. Finally, current challenges and future trends in the development of carbon-based catalysts for commercial utilization in FTS are proposed.

Flavonoids are a group of naturally occuring compounds which are widely distributed in nature. Epidemiological evidence suggests an inverse relationship between dietary intake of flavonoids and cardiovascular risk. The biological activities of flavonoids are related to their antioxidative effects. But a number of studies have found both anti and prooxidant effects for many of these compounds. This review article presents the synthetic pathways of flavonoids and discusses the structure-activity relationships between, xanthine oxidase inhibitive activities and their chemical structures, between the antioxidant and prooxidant activities and the chemical structure. Then we will show the antioxidant properties of new flavonoids in a few models. In these compounds one or two di-tert-butylhydroxyphenyl (DBHP) groups replace the catechol moiety at the position 2 of the benzopyrane heterocycle. New structures are compared with quercetin and BHT in an LDL-oxidation system, in protecting cultured bovine aortic endothelial cells against mO-LDL cytotoxicity and on myocardial functional recovery during reperfusion after 30 min global ischemia in isolated rat hearts.

Lactoferrin (Lf) is an iron-binding protein involved in host defense against infection and severe inflammation; it accumulates in the brain during neurodegenerative disorders. Before determining Lf function in brain tissue, we investigated its origin and demonstrate here that it crosses the blood-brain barrier. An in vitro model of the blood-brain barrier was used to examine the mechanism of Lf transport to the brain. We report that differentiated bovine brain capillary endothelial cells exhibited specific high (Kd = 37.5 nM; n = 90,000/cell) and low (Kd = 2 microM; n = 900,000 sites/cell) affinity binding sites. Only the latter were present on nondifferentiated cells. The surface-bound Lf was internalized only by the differentiated cell population leading to the conclusion that Lf receptors were acquired during cell differentiation. A specific unidirectional transport then occurred via a receptor-mediated process with no apparent intraendothelial degradation. We further report that iron may cross the bovine brain capillary endothelial cells as a complex with Lf. Finally, we show that the low density lipoprotein receptor-related protein might be involved in this process because its specific antagonist, the receptor-associated protein, inhibits 70% of Lf transport.

Deoxyribonucleic acid (DNA)-DNA hybridization was performed with 10 strains belonging to the “Erwinia herbicola-Enterobacter agglomerans complex” by using the competition method on nitrocellulose filters. These strains exhibited more than 75% DNA binding to Erwinia herbicola ATCC 14589T (T = type strain) and constitute DNA hybridization group 14589 (including strains ATCC 14589T and CDC 1429-71 from DNA hybridization group III [D. J. Brenner, G. R. Fanning, J. K. Leete Knutson, A. G. Steigerwalt, and M. J. Krichevsky, Int. J. Syst. Bacteriol. 34:45–55,1984]). The high level of genomic relatedness of these strains was confirmed by the similarities observed in their electrophoretic protein patterns. On the basis of our data, DNA hybridization group 14589 constitutes a discrete species within the family Enterobacteriaceae. Its closest relative is DNA hybridization group 27155 (41 to 53% DNA relatedness), which was previously defined and includes the type strains, among others, of Enterobacter agglomerans, Erwinia herbicola, and Erwinia milletiae (A. Beji, J. Mergaert, F. Gavini, D. Izard, K. Kersters, H. Leclerc, and J. De Ley, Int. J. Syst. Bacteriol. 38:77-88, 1988). We propose to unite DNA hybridization groups 14589 and 27155 in a single genus, Pantoea gen. nov. Pantoea agglomerans (Beijerinck 1888) comb. nov. is proposed to contain most strains of DNA hybridization group 27155 (including DNA hybridization group XIII of Brenner et al.), and its type strain is strain ATCC 27155 (= NCTC 9381 = LMG 1286). Pantoea dispersa sp. nov. is proposed to contain DNA hybridization group 14589, and its type strain is strain ATCC 14589 (= LMG 2603). Descriptions of the genus and its two species are given.

Lactoferrin is an iron-binding glycoprotein found in exocrine secretions of mammals and released from neutrophilic granules during inflammation. This review describes the biological roles of lactoferrin in host defence. Secreted lactoferrin exerts antimicrobial action either by chelation of iron or by destabilization of bacterial membranes. Furthermore, lactoferrin modulates the inflammatory process, mainly by preventing the release of cytokines from monocytes and by regulating the proliferation and differentiation of immune cells. Some of these activities are related to the ability of lactoferrin to bind lipopolysaccharides (LPS) with high affinity. Indeed, recent in vitro studies indicate that lactoferrin is able to compete with the LPS-binding protein for LPS binding and therefore to prevent the transfer of LPS to CD14 present at the surface of monocytes. Moreover, the prophylactic properties of lactoferrin against septicemia in vivo have been demonstrated. Taken as a whole, these observations strongly suggest that lactoferrin is one of the key molecules which modulate the inflammatory response.

Abstract The aim of this study is to evaluate the efficiency of different intumescent formulations to flame retard polylactic acid (PLA). First, the ammonium polyphosphate (APP)/pentaerythritol (PER) system is chosen because it previously demonstrated a good behavior for polyethylenic matrices. The PER is then substituted by bioresources such as lignin and starch. The flame retardant properties of the various formulations are evaluated by limiting oxygen index (LOI), UL‐94, and cone calorimetry. Compared to the PLA/APP/PER composite, the materials containing lignin and starch show lower LOI values but still commercially acceptable (superior to 32%). In contrast, the UL ratings obtained for these formulations are superior to that containing PER (V0 against V2 rating). The cone calorimeter analysis confirms the formation of an intumescent structure for the “green” composites, with a final residue corresponding to 50% of the initial sample mass and also a decrease in the peak of heat release of 50%. Finally, the composition of the formulation is optimized following a mixture design methodology to maximize the quantity of bioresources. A 32% LOI value is obtained for a composite containing 60% PLA, 12% APP, and 28% starch. Copyright © 2008 John Wiley & Sons, Ltd.