Film extrusion of sunflower protein isolate

Film extrusion of sunflower protein isolate (SFPI) was studied. The influence of die temperature (85 to 160°C), water and glycerol contents were investigated through appearance, mechanical and thermo-mechanical properties and swelling behavior in water of films. It was demonstrated that highest temperature, well above SFPI denaturation temperature in the compound, highest glycerol content (70 parts for 100 parts of SFPI) and medium water content (20 parts for 100 parts of SFPI) gave the most regular and smoothest film (as seen on SEM micrographs). Its ultimate tensile strength, Young’s modulus and strain at break were respectively: 3.2 MPa, 17.7 MPa and 73%. Soaked in water, its swelling was about 186% w/w but the film was quiet insoluble. Effect of temperature and plasticizer content were discussed in relation to the kinetic of SFPI denaturation. These first results are very promising for the development of biodegradable protein-based films

Scalar limitations of diffractive optical elements

In this paper, scalar limitations of diffractive optic components are investigated using coupled wave analyses. Results are presented for linear phase gratings and fanout devices. In addition, a parametric curve is given which correlates feature size with scalar performance

Capital-investissement et stratégies de syndication : le cas de la france

Cet article propose d’analyser les stratégies de syndication des sociétés de capital-investissement françaises et de les comparer à celles de leurs homologues européennes et nord-américaines. La syndication est en effet une stratégie qui permet globalement aux investisseurs d’améliorer leurs performances par exemple en partageant les risques ou encore en ajoutant de la valeur aux firmes. Cet article montre que les motifs de syndication varient en fonction du stade de développement de la firme que l’on finance mais aussi en fonction de la nature des sociétés de capital-investissement. Cet examen approfondi des choix de syndication du capital-investissement français, quand on les compare à ceux des sociétés localisées aux États-Unis, semble révéler une certaine « spécialisation » de ce dernier.This article proposes to analyze the syndication strategies of the French venture capital firms and to compare them with their European and North-American counterparts. Syndication is a strategy allowing investors to improve their performances for instance through risk-sharing-based and expertise-based cooperation. This paper shows that syndication motives vary depending on the stage of development of the firm financed but also depending on the type of venture capital firms. This detailed examination of the choice for syndication of French venture capital firms, compared with the one located in the United States, seems to reveal a degree of “specialization” of the French venture capital industry

Surface modification of natural fibers using bacteria: Depositing bacterial cellulose onto natural fibers to create hierarchical fiber reinforced nanocomposites

Triggered biodegradable composites made entirely from renewable resources are urgently sought after to improve material recyclability or be able to divert materials from waste streams. Many biobased polymers and natural fibers usually display poor interfacial adhesion when combined in a composite material. Here we propose a way to modify the surfaces of natural fibers by utilizing bacteria (Acetobacter xylinum) to deposit nanosized bacterial cellulose around natural fibers, which enhances their adhesion to renewable polymers. This paper describes the process of modifying large quantities of natural fibers with bacterial cellulose through their use as substrates for bacteria during fermentation. The modified fibers were characterized by scanning electron microscopy, single fiber tensile tests, X-ray photoelectron spectroscopy, and inverse gas chromatography to determine their surface and mechanical properties. The practical adhesion between the modified fibers and the renewable polymers cellulose acetate butyrate and poly(L-lactic acid) was quantified using the single fiber pullout test

Ultrastructural localization of rRNA shows defective nuclear export of preribosomes in mutants of the Nup82p complex

To study the nuclear export of preribosomes, ribosomal RNAs were detected by in situ hybridization using fluorescence and EM, in the yeast Saccharomyces cerevisiae. In wild-type cells, semiquantitative analysis shows that the distributions of pre-40S and pre-60S particles in the nucleolus and the nucleoplasm are distinct, indicating uncoordinated transport of the two subunits within the nucleus. In cells defective for the activity of the GTPase Gsp1p/Ran, ribosomal precursors accumulate in the whole nucleus. This phenotype is reproduced with pre-60S particles in cells defective in pre-rRNA processing, whereas pre-40S particles only accumulate in the nucleolus, suggesting a tight control of the exit of the small subunit from the nucleolus. Examination of nucleoporin mutants reveals that preribosome nuclear export requires the Nup82p–Nup159p–Nsp1p complex. In contrast, mutations in the nucleoporins forming the Nup84p complex yield very mild or no nuclear accumulation of preribosome. Interestingly, domains of Nup159p required for mRNP trafficking are not necessary for preribosome export. Furthermore, the RNA helicase Dbp5p and the protein Gle1p, which interact with Nup159p and are involved in mRNP trafficking, are dispensable for ribosomal transport. Thus, the Nup82p–Nup159p–Nsp1p nucleoporin complex is part of the nuclear export pathways of preribosomes and mRNPs, but with distinct functions in these two processes

Surface properties of distinct nanofibrillated celluloses assessed by inverse gas chromatography

The adhesion and surface properties of nanocelluloses are an important issue to consider when using this material for composites production, in food packaging or coatings, as well as for determining the influence of added functional groups. In the present work, the surface properties of two nanofibrillated celluloses obtained by mild 2,2,6,6-tetramethylpiperidine-1- oxyl radical (TEMPO)-mediated oxidation with distinct mechanical treatment intensity in a homogenizer (5 and 15 passes), and one nanofibrillated cellulose obtained by enzymatic process, were thoroughly assessed by inverse chromatography, at infinite dilution conditions. The dispersion component of the surface energy ( s d) was 42-46 mJ m-2 at 40 ºC for the TEMPO nanofibres and 52 mJ m-2 for the enzymatic nanocellulose. It was confirmed, based on the determination of the specific components of the works of adhesion and enthalpies of adsorption with polar probes, that the surfaces of the materials have a more Lewis acidic than Lewis basic character. Regarding TEMPO nanofibres, a slight increase of Lewis acidity/basicity ratio seemed to occur for the more nanofibrillated material (15-passes). Higher specific interactions with polar probes were found for enzymatic nanocellulose. The higher values of s d and specific interactions observed for the enzymatic nanocellulose could partly be due to the higher crystallinity of this sample. On the other hand, the increase of the acidity/basicity ratio (as well as of the s d value) for the 15-passes vs. 5-passes TEMPO nanofibres was attributed to a higher exposition of the hydroxyl groups of cellulose at the surface of the former material

Effect of plasticizers on thermal and physical properties of compression-moulded poly[(3-hydroxybutyrate)-co- (3-hydroxyvalerate)] films

[EN] Poly[(3-hydroxybutyrate)-co-(3-hydroxyvalerate)] (PHBV) is a promising bio-based, biodegradable polymer for replacing synthetic polymers, but its brittleness limits its application range. With the aim of improving the mechanical properties of PHBV films, different plasticizers (polyethylene glycol (PEG 200, 1000 and 4000), lauric acid (LA) and stearic acid (SA)) were incorporated into the film formulation at 10 wt%. All plasticized films showed lower melting temperature and crystallization degree than pure PHBV films. All plasticizers, except SA, reduced film stiffness and resistance to break, and increased the films¿ water sorption capacity and solubility as well as their water vapour permeability, but only PEG1000 yielded more extensible films. PEG1000 and PEG4000 gave rise to the most heat-resistant plasticized films, while LA and SA highly promoted the heat-sensitivity of PHBV. PEG1000 was the most effective at plasticizing PHBV films, and it was the only plasticizer that partially mitigated the ageing effects. However, a greater ratio of plasticizer would be required to adapt PHBV mechanical properties to some packaging requirements.The authors thank the Ministerio de Economia y Competitividad - Government of Spain for the financial support provided through AGL2013-42989-R Project. Author Raquel Requena thanks the Ministry of Education, Cultural and Sport - Government of Spain for a FPU Grant.Requena-Peris, R.; Jiménez Marco, A.; Vargas, M.; Chiralt, A. (2016). Effect of plasticizers on thermal and physical properties of compression-moulded poly[(3-hydroxybutyrate)-co- (3-hydroxyvalerate)] films. Polymer Testing. 56:45-53. doi:10.1016/j.polymertesting.2016.09.022S45535