A Non-Targeted Approach Unravels the Volatile Network in Peach Fruit

Volatile compounds represent an important part of the plant metabolome and are of particular agronomic and biological interest due to their contribution to fruit aroma and flavor and therefore to fruit quality. By using a non-targeted approach based on HS-SPME-GC-MS, the volatile-compound complement of peach fruit was described. A total of 110 volatile compounds (including alcohols, ketones, aldehydes, esters, lactones, carboxylic acids, phenolics and terpenoids) were identified and quantified in peach fruit samples from different genetic backgrounds, locations, maturity stages and physiological responses. By using a combination of hierarchical cluster analysis and metabolomic correlation network analysis we found that previously known peach fruit volatiles are clustered according to their chemical nature or known biosynthetic pathways. Moreover, novel volatiles that had not yet been described in peach were identified and assigned to co-regulated groups. In addition, our analyses showed that most of the co-regulated groups showed good intergroup correlations that are therefore consistent with the existence of a higher level of regulation orchestrating volatile production under different conditions and/or developmental stages. In addition, this volatile network of interactions provides the ground information for future biochemical studies as well as a useful route map for breeding or biotechnological purposes

Thermophysical analysis of thermal oils for use in thermocline storage systems,

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Unexpected behaviour of multi-walled carbon nanotubes during "in situ" polymerization process: When carbon nanotubes act as initiators and control agents for radical polymerization

cited By 8International audienceRaw multi-walled carbon nanotubes (MWCNTs) were used, without an initiation agent, to initiate and self-control polymerization of poly(acrylic acid) and poly(methyl methacrylate) copolymers. To enhance the livingness of the radical polymerization, a stable nitroxide can be added to strongly reduce the rate energy of the macromolecular chains growth and their dispersion. During the auto-initiation and self-control processes of the radical polymerization, the grafting of the copolymers onto the MWCNTs surface has been observed and characterized by transmission electronic microscopy (TEM). In particular, the grafting can be achieved thanks to an "in situ" radical polymerization that can simultaneously lead to the grafting of the MWCNTs and improve the dispersion. This work represents a real insight and breakthrough because in one step, MWCNTs acting as chemical motors are grafted and the growth of copolymer chains is well controlled

Multi-walled carbon nanotubes as unexpected accelerators of chemical reactions

cited By 0International audienceThe influence of carbon nanotubes on various chemical reactions has been examined. These reactions include epoxy crosslinking, in situ polymerization of copolymers in the presence of carbon nanotubes and thermal degradation of a thermoplastic matrix. The various characterizations were based on different types of analyses, including differential scanning calorimetry, proton nuclear magnetic resonance, size exclusion chromatography and thermogravimetric analysis. In each case, we show that the presence of multi-walled carbon nanotubes accelerates the process. © 2012 Society of Chemical Industry Multi-walled carbon nanotubes can accelerate various chemical reactions: epoxy crosslinking, in situ polymerization of copolymers and thermal degradation of a thermoplastic matrix

Nanorheology of adsorbed polymer chains immersed in pure solvent

Long linear chains of polybutadiene are adsorbed on the two surfaces of a surface force apparatus and immersed in pure tetradecane. The hydrodynamic force was measured by drainage experiments and by frequency sweeps at constant distances. We related the hydrodynamic thickness to the chain dimension. The complex modulus encompasses the shear modulus and, at distances lower than the hydrodynamic thickness, a compression modulus. The compression term was related to the static force which appears when the two adsorbed layers are overlapped. The complex shear modulus was interpreted by a two-components hydrodynamic model proposed by P. Sens et al. We first complemented the theoretical model. Then, our experimental data fit the proposed viscoelastic expressions in the entire range of distances. The storage modulus is supposed to be affected by a residue of free chains and by the dispersion of the loop lengths