Influence of citric acid and water on thermoplastic wheat flour/poly(lactic acid) blends. I: Thermal, mechanical and morphological properties

Wheat flour was plasticized with glycerol and compounded with poly(lactic acid) in a one-step twin-screw extrusion process in the presence of citric acid with or without extra water. The influence of these additives on process parameters and thermal, mechanical and morphological properties of injected samples from the prepared blends, was then studied. Citric acid acted as a compatibilizer by promoting depolymerization of both starch and PLA. For an extrusion without extra water, the amount of citric acid (2 parts for 75 parts of flour, 25 parts of PLA and 15 parts of glycerol) has to be limited to avoid mechanical properties degradation. Water, added during the extrusion, improved the whole process, minimizing PLA depolymerization, favoring starch plasticization by citric acid and thus improving phases repartition

Influence of citric acid on thermoplastic wheat flour/poly (lactic acid) blends. II. Barrier properties and water vapor sorption isotherms

The effects of citric acid on wheat flour/glycerol/poly(lactic) acid (PLA) blends prepared by one-step twin-screw extrusion have been studied to improve barrier properties of starch based materials. A series of injected samples were produced from prepared compounds with varying ratio (0-20 part) of citric acid. The effects of citric acid on the water vapor permeability, oxygen permeability and water solubility in the film were then investigated. The barrier properties results proved that citric acid behaves as compatibilizing agent between starch and PLA phases for ratios between 0 and 10 parts. When the added amount exceeds 10 parts, CA acted as a plasticizer and/or promoted the hydrolysis of the starch glycosidic bonds

Theoretical and experimental studies of critical microemulsions

We report on the extension of the droplet model to account for static and dynamic light scattering studies of a ternary water-in-oil microemulsion close to its critical point. This model, which assumes that the critical microemulsion droplets are forming transient polydisperse fractal aggregates, reproduces well the usual features of critical phenomena and is also able to account, in a very natural way, for the dynamical background effects evidenced experimentaly.Le modèle des gouttelettes a été étendu pour rendre compte de la diffusion statique et dinamique de la lumière par une microemulsion critique ternaire eau dans huile. En supposant que les gouttelettes forment des agrégats polydispersés de nature fractale, on peut rendre compte avec une excellente précision des phénomènes observés. En particulier on décrit les effets du fond dynamique mis en évidence expérimentalement

Immunohistochemical characteristic of myoma tissue in patients with uterine leiomyoma after treatment with ulipristal acetate.

Background. Uterine leiomyoma is one of the most common benign tumors of the female genital organs. The main conservative treatment of leiomyoma is progesterone receptor blockers that suppress myoma growth and may lead to its regression. Objective. To study the immunohistochemical features of myoma tissue in patients with uterine leiomyoma after treatment with selective progesterone modulator - ulipristal acetate. Methods. Leiomyoma tissue obtained from 9 patients after ulipristal acetate treatment were investigated. Group for comparison - leiomyoma from patients without hormonal therapy. Immunohistochemical study of progesterone and estrogen receptors, proliferative activity marker Ki-67 and inhibitor of apoptosis Bcl-2 was performed. Results. In the group of patients without preoperative hormonal treatment progesterone receptors were expressed in 76,4±6,8% of the nuclei, estrogen receptors - in 32,8±2,6%. In the group of patients after treatment with ulipristal acetate there was a significant decrease of progesterone receptor expression – 36,8±1,28% (p 0,05) . Bcl-2 in the control group was found in 65,4±7,2% cells, in leiomyoma after treatment there was a significant decrease of bcl-2 – 42,6±3,2% (p <0, 05). In leiomyomas without hormonal treatment Ki-67 was determined in 11,8% of the nuclei of smooth muscle cells, and in leiomyomas after ulipristal acetate – in 7,2% leiomyoma cells. Conclusions. In patients after three months of ulipristal acetate treatment there was a significant decrease of expression of progesterone receptor, bcl-2, and Ki-67. Taken together these data evidence reduced action of progesterone on leiomyoma cells, induction of apoptosis and decreased proliferation processes that may cause involution of fibroids

Twin-Screw Extrusion: a key technology for the biorefinery

International audienceFor more than 30 years, the Laboratory of Agro-industrial Chemistry (LCA) develops an ambitious and multi-scale research topic on the use of twin-screw extrusion (TSE) for the processing of biomass for non-food applications. This chapter will give an overview of past and present projects, discussing specific operating conditions and their consequences on biopolymer native organization. For the production of agro-materials, compounding processes have been designed and in some cases industrialized integrating specific targeted actions such as the plasticization of primary cell-walls (sugar beet, tobacco), the "fusion" of storage polymers (starch, oilseed proteins) and/or the destructuring of secondary cell-walls (lignocellulosic fibers). For the pretreatment of lignocellulosic fibers, the conjugated use of chemicals is also discussed. Those processes have also been coupled with biodegradable polyester blending (involving compatibilization with acid citric) and compounding. In integrated biorefining processes, TSE may also be used simultaneously as a continuous liquid-solid extractor through mechanical pressing or solvent extraction, for extracting oil, polysaccharides, proteins, polyphenols or hydroxycinnamic acids and as a pre-treatment of the fibrous raffinate. This is especially efficient for the processing of oilseed crops and the production of binderless fiberboards or to prepare technical fibers for composite applications. This has been widely demonstrated on sunflower, jatropha or more recently coriander. Finally, in the bioenergy field, a specific pretreatment process for the production of bioethanol from lignocellulosic feedstock has been developed and is actually in the up-scaling phase. Integrating the use of enzymes in a one-step TSE, this process has been called "bioextrusion"