Tuning the functional properties of lignocellulosic films by controlling the molecular and supramolecular structure of lignin.

This study investigated the relationships between lignin molecular and supramolecular structures and their functional properties within cellulose-based solid matrix, used as a model biodegradable polymer carrier. Two types of derivatives corresponding to distinct structuration levels were prepared from a single technical lignin sample (PB1000): phenol-enriched oligomer fractions and colloidal nanoparticles (CLP). The raw lignin and its derivatives were formulated with cellulose nanocrystals or nanofibrils to prepare films by chemical oxidation or pressure-assisted filtration. The films were tested for their water and lignin retention capacities, radical scavenging capacity (RSC) and antimicrobial properties. A structural investigation was performed by infrared, electron paramagnetic resonance spectroscopy and microscopy. The composite morphology and performance were controlled by both the composition and structuration level of lignin. Phenol-enriched oligomers were the compounds most likely to interact with cellulose, leading to the smoothest film surface. Their RSC in film was 4- to 6-fold higher than that of the other samples. The organization in CLP led to the lowest RSC but showed capacity to trap and stabilize phenoxy radicals. All films were effective against S. aureus (gram negative) whatever the lignin structure. The results show the possibility to tune the performances of these composites by exploiting lignin multi-scale structure.

[Compartment syndrome and sport traumatology]. / Syndrome des loges en traumatologie du sport.

Compartment syndrome is defined as an increased intracompartmental pressure within inelastic fascia which surround muscular compartments. That pathology can be either acute or chronic. The acute situation is generally a medical emergency. Unless a fasciotomy is rapidly performed, increasing pressure may completely cut off blood flow and cause necrosis of the affected limb. The chronic compartment syndrome, more frequent, is characterized by exercise-induced pain and swelling that is relieved by rest. It results from an excessive intra-muscular pressure increase. The anterior compartment of the leg is most commonly involved. To accurately diagnose the compartment syndrome, physicians perform measurements of compartment pressure. By means of miniature digital instruments, exercise and rest intramuscular pressure are recorded. If pressures reach the critical threshold (30 mm Hg) and remain high five minutes after exercise, compartment syndrome is present. Treatment is nearly exclusively surgical. It consists in an fasciotomy allowing a complete recovery and a return to sport activities.

[Application of hydrophobic chromatography to the fractionation of wheat prolamins]. / Application de la chromatographie d'interaction hydrophobe au fractionnement des prolamines du blé tendre.

Hydrophobic chromatography is applied to the fractionation of wheat prolamins. Proteins are separated on "Phenyl Sepharose CL 4B" column. They are eluted by variations of pH and polarity of solvent. Components with the same electrophoretic mobility appear in several chromatographic fractions and gliadin groups, as indicated by Woychick classification, are heterogeneous. This method is excepted to give new information about interaction properties of gluten proteins.