Institut de Chimie de Clermont-Ferrand

Abstract. The present paper reviews existing knowledge with regard to Organic Aerosol (OA) of importance for global climate modelling and defines critical gaps needed to reduce the involved uncertainties. All pieces required for the representation of OA in a global climate model are sketched out with special attention to Secondary Organic Aerosol (SOA): The emission estimates of primary carbonaceous particles and SOA precursor gases are summarized. The up-to-date understanding of the chemical formation and transformation of condensable organic material is outlined. Knowledge on the hygroscopicity of OA and measurements of optical properties of the organic aerosol constituents are summarized. The mechanisms of interactions of OA with clouds and dry and wet removal processes parameterisations in global models are outlined. This information is synthesized to provide a continuous analysis of the flow from the emitted material to the atmosphere up to the point of the climate impact of the produced organic aerosol. The sources of uncertainties at each step of this process are highlighted as areas that require further studies.

An oxygen-rich carbon for supercapacitors has been obtained by one-step carbonization of a natural biopolymer from seaweeds, e.g., sodium alginate. Although the specific surface area of this carbon is very low, it gives a capacitance comparable to the best activated carbons available. Due to its low porosity (see figure), this material has high density and good electrical conductivity, also advantageous for supercapacitor applications.

The present paper describes the synthesis and characterization of nanocomposite materials built from the assembly of organic polymers and two-dimensional host materials, particularly reviewing those composed of layered double hydroxide (LDH) inorganic frameworks. When the meaning commonly adopted for nanocomposites is narrowed, the system is constituted of sheets lying on top of each other in which covalent forces maintain the chemical integrity and define an interlamellar gap filled up with the polymer guest. The situation is different from an inorganic filler dispersed into a polymeric matrix. The incorporation of polymer between the galleries proceeds via different pathways such as coprecipitation, exchange, in situ polymerization, surfactant-mediated incorporation, hydrothermal treatment, reconstruction, or restacking. The latter method, recently effective via the exfoliation of the LDH layers, appears to be more favorable, in terms of crystallinity, to capture monomer entities than the whole polymer. The nanocomposites are enlisted according to the preparation pathways. It is found that these multicomponent systems are thermally more stable than the pristine inorganic compounds, leading, for example, to potential applications in flame-retardant composites. A large variety of LDH/polymer systems may be tailored considering the highly tunable intralayer composition coupled to the choice of the organic moiety. The paper concludes with a brief discussion underlining the perspectives. Despite their appeal, the polymer/LDH class of nanocomposites has not yet been extensively studied for applications.

OBJECTIVE: There is substantial inter-individual diversity in the susceptibility of alcoholics to liver injury. Alterations of intestinal microbiota (IM) have been reported in alcoholic liver disease (ALD), but the extent to which they are merely a consequence or a cause is unknown. We aimed to demonstrate that a specific dysbiosis contributes to the development of alcoholic hepatitis (AH). DESIGN: We humanised germ-free and conventional mice using human IM transplant from alcoholic patients with or without AH. The consequences on alcohol-fed recipient mice were studied. RESULTS: A specific dysbiosis was associated with ALD severity in patients. Mice harbouring the IM from a patient with severe AH (sAH) developed more severe liver inflammation with an increased number of liver T lymphocyte subsets and Natural Killer T (NKT) lymphocytes, higher liver necrosis, greater intestinal permeability and higher translocation of bacteria than mice harbouring the IM from an alcoholic patient without AH (noAH). Similarly, CD45+ lymphocyte subsets were increased in visceral adipose tissue, and CD4(+)T and NKT lymphocytes in mesenteric lymph nodes. The IM associated with sAH and noAH could be distinguished by differences in bacterial abundance and composition. Key deleterious species were associated with sAH while the Faecalibacterium genus was associated with noAH. Ursodeoxycholic acid was more abundant in faeces from noAH mice. Additionally, in conventional mice humanised with the IM from an sAH patient, a second subsequent transfer of IM from an noAH patient improved alcohol-induced liver lesions. CONCLUSIONS: Individual susceptibility to ALD is substantially driven by IM. It may, therefore, be possible to prevent and manage ALD by IM manipulation.

Use of electronic cigarettes has grown exponentially over the past few years, raising concerns about harmful emissions. This study quantified potentially toxic compounds in the vapor and identified key parameters affecting emissions. Six principal constituents in three different refill "e-liquids" were propylene glycol (PG), glycerin, nicotine, ethanol, acetol, and propylene oxide. The latter, with mass concentrations of 0.4-0.6%, is a possible carcinogen and respiratory irritant. Aerosols generated with vaporizers contained up to 31 compounds, including nicotine, nicotyrine, formaldehyde, acetaldehyde, glycidol, acrolein, acetol, and diacetyl. Glycidol is a probable carcinogen not previously identified in the vapor, and acrolein is a powerful irritant. Emission rates ranged from tens to thousands of nanograms of toxicants per milligram of e-liquid vaporized, and they were significantly higher for a single-coil vs a double-coil vaporizer (by up to an order of magnitude for aldehydes). By increasing the voltage applied to a single-coil device from 3.3 to 4.8 V, the mass of e-liquid consumed doubled from 3.7 to 7.5 mg puff(-1) and the total aldehyde emission rates tripled from 53 to 165 μg puff(-1), with acrolein rates growing by a factor of 10. Aldehyde emissions increased by more than 60% after the device was reused several times, likely due to the buildup of polymerization byproducts that degraded upon heating. These findings suggest that thermal degradation byproducts are formed during vapor generation. Glycidol and acrolein were primarily produced by glycerin degradation. Acetol and 2-propen-1-ol were produced mostly from PG, while other compounds (e.g., formaldehyde) originated from both. Because emissions originate from reaction of the most common e-liquid constituents (solvents), harmful emissions are expected to be ubiquitous when e-cigarette vapor is present.

Mono-dispersed sub-micron sized hydrotalcite-like compounds (HTlcs), [Mg1−xAlx(OH)2](CO3)y·2H2O, were synthesized by the urea hydrolysis method. The as-prepared compounds display platelet-like primary particles with a hexagonal shape. The breadth to thickness ratio can be varied by changing the synthesis conditions such as the precipitation rate or the medium nature. The factors influencing the secondary particle morphology (or aggregates) are also discussed. The results are compared to the constant pH coprecipitation method, commonly used for HTlcs.

Delamination of the layered double hydroxide structure [Zn2Al(OH)6][C12H25SO4 ·nH2O] was realized by dispersion in butanol; translucent colloidal solutions are stable for at least 8 months with oriented LDH materials with extended crystallite size being obtained; the results presented here suggest that total delamination occurs in the colloidal solution.

The present work describes, for the first time, the use of a new and strong complexing agent, ethylenediamine-N,N'-disuccinic acid (EDDS) in the homogeneous Fenton process. The effect of H(2)O(2) concentration, Fe(III)-EDDS concentration, pH value, and oxygen concentration on the homogeneous Fenton degradation of bisphenol A (BPA) used as a model pollutant, was investigated. Surprisingly, the performance of BPA oxidation in an EDDS-driven Fenton reaction was found to be much higher at near neutral or basic pH than at acidic pH. Inhibition and probe studies were conducted to ascertain the role of several radicals (e.g., (•)OH, HO(2)(•)/O(2)(•-)) on BPA degradation. This unexpected effect of pH on Fenton reaction efficiency could be due to the formation of HO(2)(•) or O(2)(•-) radicals and to the presence of different forms of the complex Fe(III)-EDDS as a function of pH. Indeed, the reduction of Fe(III)-EDDS to Fe(II)-EDDS is a crucial step that governs the formation of hydroxyl radical, mainly responsible for BPA degradation. In addition to its ability to maintain iron in soluble form, EDDS acts as a superoxide radical-promoting agent, enhancing the generation of Fe(II) (the rate limiting step) and therefore the production of (•)OH radicals. These results are very promising because they offer an important new treatment option at higher range of pH values and more particularly at pHs encountered in natural conditions.

A novel, sensitive electrochemical immunoassay has been developed using a colloidal gold label that, after oxidative gold metal dissolution in an acidic solution, was indirectly determined by anodic stripping voltammetry (ASV) at a single-use carbon-based screen-printed electrode (SPE). The use of disposable electrodes allows for simplified measurement in 35 microL of solution. The method was evaluated for a noncompetitive heterogeneous immunoassay of an immunoglobulin G (IgG) and a concentration as low as 3 x 10(-12) M was determined, which is competitive with colorimetric ELISA or with immunoassays based on fluorescent europium chelate labels. The high performance of the method is related to the sensitive ASV determination of gold(III) at a SPE (detection limit of 5 x 10(-9) M) and to the release of a large number of gold(III) ions from each gold particle anchored on the immunocomplex (e.g., 1.7 x 10(5) gold atoms are theoretically contained in a 18-nm spherical gold particle).

New weapons to fight cancer are constantly needed. Among chemotherapeutics, anti-cancer metal-drugs have enjoyed a long and successful history since the discovery of the benchmark cisplatin. Advances in metal-drug discovery have motivated chemists to build plethora of complex structures. Among them, a novel area is emerging. This article presents a survey of the metal-N-Heterocyclic Carbenes (Ag(I), Au(I), Pd(II) and Cu(I)-NHCs) as potential anti-cancer agents. Most of the metal-NHCs considered display higher cytotoxicities than the reference metallo-drug cisplatin. Some of them are even selective for particular cell lines. Their mechanisms of action at the cellular level are further discussed, showing that the nature of the metal is of great importance. All these promising results demonstrate that this approach deserves more attention and work.

We have fabricated transistor structures using fluorinated single-layer graphene flakes and studied their electronic properties at different temperatures. Compared with pristine graphene, fluorinated graphene has a very large and strongly temperature-dependent resistance in the electroneutrality region. We show that fluorination creates a mobility gap in graphene's spectrum where electron transport takes place via localized electron states.

Metasurfaces are ultrathin optical elements that are highly promising for constructing lightweight and compact optical systems. For their practical implementation, it is imperative to maximize the metasurface efficiency. Topology optimization provides a pathway for pushing the limits of metasurface efficiency; however, topology optimization methods have been limited to the design of microscale devices due to the extensive computational resources that are required. We introduce a new strategy for optimizing large-area metasurfaces in a computationally efficient manner. By stitching together individually optimized sections of the metasurface, we can reduce the computational complexity of the optimization from high-polynomial to linear. As a proof of concept, we design and experimentally demonstrate large-area, high-numerical-aperture silicon metasurface lenses with focusing efficiencies exceeding 90%. These concepts can be generalized to the design of multifunctional, broadband diffractive optical devices and will enable the implementation of large-area, high-performance metasurfaces in practical optical systems.

Plastics are ubiquitous in the oceans and constitute suitable matrices for bacterial attachment and growth. Understanding biofouling mechanisms is a key issue to assessing the ecological impacts and fate of plastics in marine environment. In this study, we investigated the different steps of plastic colonization of polyolefin-based plastics, on the first one hand, including conventional low-density polyethylene (PE), additivated PE with pro-oxidant (OXO), and artificially aged OXO (AA-OXO); and of a polyester, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), on the other hand. We combined measurements of physical surface properties of polymers (hydrophobicity and roughness) with microbiological characterization of the biofilm (cell counts, taxonomic composition, and heterotrophic activity) using a wide range of techniques, with some of them used for the first time on plastics. Our experimental setup using aquariums with natural circulating seawater during 6 weeks allowed us to characterize the successive phases of primo-colonization, growing, and maturation of the biofilms. We highlighted different trends between polymer types with distinct surface properties and composition, the biodegradable AA-OXO and PHBV presenting higher colonization by active and specific bacteria compared to non-biodegradable polymers (PE and OXO). Succession of bacterial population occurred during the three colonization phases, with hydrocarbonoclastic bacteria being highly abundant on all plastic types. This study brings original data that provide new insights on the colonization of non-biodegradable and biodegradable polymers by marine microorganisms.

In this review, attention is initially focused upon the evolution of the Newton-Laplace Equation, that links the measured speed of sound in a fluid in conjunction with its density, to a reliable estimate of its isentropic compressibility κS. Definitions of ideal and excess isentropic quantities are formulated on the premise that the thermodynamic properties of an ideal mixture are mutually related in the same manner as are those of a real mixture or a pure substance. It is shown that both intensive and extensive properties can be derived from the ideal Gibbs energy. Different approaches previously used to calculate ideal isentropic quantities are examined and some subtle errors are identified. The consequences of using conflicting definitions are pointed out. Isentropic pressure derivatives obtained under different conditions and empirical models for estimating the differences between ultrasonic speeds in real and ideal liquid mixtures are discussed.

Driven by the scientific challenges involved in the creation of nanostructures providing access to new materials with unusual properties, the study of hybrid materials based on Layered Double Hydroxides (LDHs) has developed considerably during the last decade. This feature article is intended to give a broad overview of organic–inorganic hybrid assemblies based on LDH materials including their synthesis and characterization, and pointing out their potential applications. The LDH interlayer gap supplies an interesting, constrained environment arising from the anisotropic accommodation of the guest molecule at the nanoscale. Particularly, this article underlines the importance of compatibility between the two components, i.e. the organic and inorganic parts, in terms of charge distribution and molecular size for the polymerization process of interleaved molecules. Exfoliation and staging phenomena are also described. Through several examples of the shape and function of interlayer organic anions, hybrid LDH materials are described for their potential properties in optic devices, as drug delivery systems, and also as nano- and macro-fillers in polymer nanocomposites and cements, respectively. Eventually, LDH hybrid materials merge into even more complex systems for which topical applications are listed.

Abstract Hybrid materials based on layered double hydroxides (LDHs) exhibit great potential in diverse fields such as health care, polymer composites, environment, catalysis, and energy generation. Indeed, the compositional flexibility and the scalability of LDH structures, their low cost, and their ease of synthesis have made hybrid LDHs extremely attractive for constructing smart and high‐performance multifunctional materials. This review provides a comprehensive and critical overview of the current research on multifunctional hybrid LDHs. Organic–inorganic hybrid LDHs, intercalated and surface‐immobilized structures, are both specifically addressed. The new trends and strategies for hybrid LDH synthesis are first described, and then the potential of the latest hybrid LDHs, polymer LDH nanocomposites, and LDH bio‐nanocomposites are presented. Significant achievements published from ≈2010, including authors' results, which employ hybrid LDH assemblies in materials science, medicine, polymer nanocomposites, cement chemistry, and environmental technologies, are specifically addressed. It is concluded with remarks on present challenges and future prospects.

A model is introduced to predict the energy of metal-to-metal charge-transfer transitions in oxide compounds containing Bi(3+) ions and d(0) or d(10) metals (M(n+)). The model takes into account the structural characteristics of the host lattices, the anion relaxation resulting from Bi(3+) doping, and the electronegativities and coordination numbers of the Bi(3+) and M(n+) ions in the compounds. It is shown, through a critical review of the archival literature, that this model provides new insights on the assignment of the luminescence spectra and the related interpretation of the spectroscopic behaviors.

This critical review is an updated survey of metal-carbenes as potential anticancer chemotherapeutics. We report on the recent advances in the discovery of N-heterocyclic carbenes, acyclic diamino carbenes and abnormal NHCs associated with metals from groups 10 and 11 that displayed antiproliferative activity and emphasize, when possible, their molecular target(s) and their mechanism of action.

The dissolution of microcrystalline cellulose in 1-butyl-3-methylimidazolium acetate [C4C1Im][OAc] was studied using a solid–liquid equilibrium method based on polarized-light optical microscopy from 30 to 100 °C. We found that [C4C1Im][OAc] could dissolve as much as 25 wt% of cellulose at temperatures below 100 °C. The structure of the composite phase obtained after cooling a solution of 16 wt% of cellulose in [C4C1Im][OAc] was analyzed by low angle X-ray diffraction showing the absence of microcrystalline cellulose, but depicting an extensive long range isotropic ordering. With the aim of improving the dissolution of cellulose in the ionic liquid, dimethyl sulfoxide, DMSO, was added as a co-solvent. It was observed that it enhances the solvent power of the ionic liquid by decreasing the time needed for dissolution, even at low temperatures. In order to understand what makes DMSO a good co-solvent, two approaches were followed. Firstly, we studied experimentally the mass transport properties (viscosity and ionic conductivity) of [C4C1Im][OAc] + DMSO mixtures at different compositions and, secondly, we assessed the molecular structure and interactions around glucose, the structural unit of cellulose, by means of molecular dynamics simulations. As expected, DMSO dramatically decreases the viscosity and increases the conductivity of the mixtures, but without inducing cation–anion dissociation in the ionic liquid. These results were confirmed by molecular simulation as it was found that the presence of a 0.5 mole fraction concentration of DMSO does not significantly affect the hydrogen-bond network in the ionic liquid. Furthermore, molecular dynamics shows that in the [C4C1Im][OAc] + DMSO equimolar mixture, DMSO does not interact specifically with glucose. We conclude that DMSO improves the solvation capabilities of the ionic liquid because it facilitates mass transport by decreasing the solvent viscosity without significantly affecting the specific interactions between cations and anions or between the ionic liquid and the polymer. The behavior of DMSO as a co-solvent was compared with that of water and it was found that water molecules are more probably found near glucose than those of DMSO, thus interfering with ionic liquid–glucose interactions, which might explain the unsuitability of water as a co-solvent for cellulose in ionic liquids.

Thanks to their high biocompatibility and bioactivity, bioactive glasses are very promising materials for soft and hard tissue repair and engineering. Because bioactivity and specific surface area intrinsically linked, the last decade has seen a focus on the development of highly porous and/or nano-sized materials. This review emphasizes the synthesis of bioactive glass nanoparticles and materials design strategies. The first part comprehensively covers mainly soft chemistry processes, which aim to obtain dispersible and monodispersed nanoparticles. The second part discusses the use of bioactive glass nanoparticles for medical applications, highlighting the design of materials. Mesoporous nanoparticles for drug delivery, injectable systems and scaffolds consisting of bioactive glass nanoparticles dispersed in a polymer, implant coatings and particle dispersions will be presented.