Nisin is a natural preservative for many food products. This bacteriocin is mainly used in dairy and meat products. Nisin inhibits pathogenic food borne bacteria such as Listeria monocytogenes and many other Gram-positive food spoilage microorganisms. Nisin can be used alone or in combination with other preservatives or also with several physical treatments. This paper reviews physicochemical and biological properties of nisin, the main factors affecting its antimicrobial effectiveness, and its food applications as an additive directly incorporated into food matrices.

This paper details the characteristics of pure cellulose and wood fibers when associated with thermoplastic matrices for composite applications. Chemical modification of the cellulose is performed to allow a good compatibilization, and the most efficient compatibilizing agents must possess: (i) a function highly reactive with the OH groups of the cellulose and (ii) a non‐polar chain with preferably a polymeric structure. Polypropylenes grafted with maleic anhydride are thus efficient agents. Smaller compatibilizing agents, especially if reacted with cellulose in swelling media, react with the bulk of the fiber and lead to dimensional stability. All treatments, even when performed with low degrees of grafting or small alkyl chains, significantly modify the hydrophilicity of the cellulose surface and play a role in a better wettability of the fiber by the matrix leading to improved adherence. The global mechanical properties are then improved, but the effect is preferably studied at the scale of a single filament composite. The morphology of the matrix in the vicinity of the non‐treated fiber shows that, in some cases, the fiber acts as a nucleating agent involving the formation of a transcrystalline phase. Aging in moisture is generally detrimental to the mechanical properties. This phenomenon is limited by the chemical treatment performed on the fibers.

No abstract

No abstract

A comparison of the plasticizing efficiency of a series of molecules introduced in dry and hydrated Kraft lignin demonstrated that the plasticization mechanisms are different before and after sorption site saturation. Lignins were plasticized in two steps and glass transition decrease was determined from DSC measurements. "Specific sorption plasticizers," such as water, are very efficient in low content because of their functionality and accessibility to sorption sites. The plasticizing efficiency does not depend on the solubility parameter, and is well quantified, considering the molar concentration of donor/acceptor functions. After saturation of sorption sites (in wet conditions), the plasticizing efficiency depends on the solubility parameter, which should be close to that of the polymer matrix.

Background: In bovine maturing oocytes and cleavage stage embryos, gene expression is mostly controlled at the posttranscriptional level, through degradation and deadenylation/polyadenylation. We have investigated how post transcriptional control of maternal transcripts was affected during in vitro and in vivo maturation, as a model of differential developmental competence.

No abstract

Composite polyimide-silica materials have been synthesized via the sol-gel process and their gas transport properties studied. Structural characterizations have been performed showing that materials prepared with large concentration of silicon alkoxyde are composites made of silica particles embedded in the polyimide matrix while low-silicon alkoxyde concentration induces homogeneous materials. X-ray diffraction shows that the presence of silicon species induces modifications in the microstructure of the polyimide chains. These modifications have been confirmed by a shift of the glass transition temperature and density variations. Influence of the temperature and silicon species on the gas transport have been studied using various gases (nitrogen, oxygen, carbon dioxide, and methane) showing that gas permeation coefficients increase with the silicon species proportion. CO 2 sorption measurements have been performed at various temperatures and the results have been analyzed in terms of the dual sorption theory. Activation energies have been calculated for the permeation and sorption mechanisms. These results show that silicon species contributes to the overall permeability.