329 research outputs found

    Preparation of aqueous dispersion of thermoplastic sizing agent for carbon fiber by emulsion/solvent evaporation

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    In this work, different sizing agent aqueous dispersions based on polyetherimide (PEI) were elaborated in order to improve the interface between carbon fibers and a thermoplastic matrix (PEEK). The dispersions were obtained by the emulsion/solvent evaporation technique. To optimize the stability and the film formation on the fibers, two surfactants were tested at different concentrations, with different concentrations of PEI. The dispersions obtained were characterized by dynamic light scattering (DLS) and the stability evaluated by analytical centrifugation (LUMiFuge). The selected dispersions were tested for film formation ability by scanning electron microscopy (SEM), and the sizing performance was assessed by observation of the fiber/matrix interface by SEM. The results revealed that an aqueous dispersion of PEI,stabilized by sodium dodecyl sulfate as the surfactant, led to very stable sizing agent aqueous dispersion with ideal film formation and better interface adhesion

    EU Competition Policy Revisited: Economic Doctrines Within European Political Work

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    European Union competition policy is often described as neoliberal, without this leading to more investigation. This paper highlights how the European Competition policy doctrine has been shaped, how the ordoliberal movement and the Chicago school ideas have been implemented and supported by the political work of some key actors. We show that, contrary to what is sometimes said in literature, ordoliberal actors were neither hegemonic nor leaders between Rome Treaty and the eighties, even if some neoliberal principles were introduced in antitrust law. These laws are much more a compromise between French and German representatives, and between neo-mercantilists and ordoliberals. However, things have dramatically changed since the eighties, when both (1) new political work from members of the Commission introduced in the European competition policy elements of Chicago School doctrine to complete the European market and (2) some decisions from the ECJ clarified the doctrine of EU Competition law. Nowadays, European competition policy is a mix between an ordoliberal spirit and some Chicago School doctrinal elements.competition, policy, European Union, neoliberalism, ordoliberalism, political work

    Spectroscopic detection of carbon nanotube interaction with amphiphilic molecules in epoxy resin composites

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    Incorporation of carbon nanotubes into epoxy resin composites has the effect of increasing electrical conductivity at low percolation levels. An amphiphilic molecule such as palmitic acid has been used to increase the surface contact area and improve the dispersion of the carbon nanotube bundles in the prepolymer. The chemical environment of the dispersed nanotubes has been probed using vibrational Raman spectroscopy. Spectroscopic Raman maps, on sample surfaces (60x60 ”m2) with ratios of nanotubes to palmitic acid varying from 1:2 to 2:1 by weight, have been recorded to test the uniformity of the dispersion. Substantial spatial inhomogeneities have been observed in the G-band shift and an additional spectral band at 1450 cm-1. The 1450 cm-1 band has been attributed to the CH3 group of the amphiphilic molecules adsorbed onto the nanotube surface. The maps are correlated with the measured electrical conductivity values. The highest conductivity has been observed for the best dispersed nanotubes and nanotubes with the highest degree of interaction

    Evolution of transanal total mesorectal excision for rectal cancer: From top to bottom

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    The gold standard for curative treatment of locally advanced rectal cancer involves radical resection with a total mesorectal excision (TME). TME is the most effective treatment strategy to reduce local recurrence and improve survival outcomes regardless of the surgical platform used. However, there are associated morbidities, functional consequences, and quality of life (QoL) issues associated with TME; these risks must be considered during the modern-day multidisciplinary treatment for rectal cancer. This has led to the development of new surgical techniques to improve patient, oncologic, and QoL outcomes. In this work, we review the evolution of TME to the transanal total mesorectal excision (TaTME) through more traditional minimally invasive platforms. The review the development, safety and feasibility, proposed benefits and risks of the procedure, implementation and education models, and future direction for research and implementation of the TaTME in colorectal surgery. While satisfactory short-term results have been reported, the procedure is in its infancy, and long term outcomes and definitive results from controlled trials are pending. As evidence for safety and feasibility accumulates, structured training programs to standardize teaching, training, and safe expansion will aid the safe spread of the TaTME

    Evaluation of Organogel Nanoparticles as Drug Delivery System for Lipophilic Compounds

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    The purpose of the study was to evaluate organogel nanoparticles as a drug delivery system by investigating their stability, according to the formulation strategy, and their release profile. The gelled nanoparticles were prepared by hot emulsification (above the gelation temperature) of an organogel in water, and cooling at room temperature. In the first step, we used DLS and DSC to select the most suitable formulations by optimizing the proportion of ingredients (HSA, PVA, castor oil) to obtain particles of the smallest size and greatest stability. Then, two lipophilic drug models, indomethacin and ketoconazole were entrapped in the nanoparticles made of castor oil gelled by 12-hydroxystearic acid. Thermal studies (DSC) confirmed that there was no significant alteration of gelling due to the entrapped drugs, even at 3% w/w. Very stable dispersions were obtained (>3 months), with gelled oil nanoparticles presenting a mean diameter between 250 and 300 nm. High encapsulation efficiency (>98%) was measured for indomethacin and ketoconazole. The release profile determined by in vitro dialysis showed an immediate release of the drug from the organogel nanoparticles, due to rapid diffusion. The study demonstrates the interest of these gelled oil nanoparticles for the encapsulation and the delivery of lipophilic active compounds

    Effects of different poultry manure fertilization levels and cutting times on Moringa oleifera production

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    Abstract The effects of different poultry manure fertilization levels and cutting times on the growth of Moringa oleifera were evaluated. A factorial design comparing six levels of poultry manure (0, 50, 100, 150, 200 and 250 kg N ha-1) and three cutting times (4, 6 and 8 months) with four replicates was used. One month after sowing, fertilization was performed. At each cutting time, 20 plants were collected per treatment for height and diameter measurements. Stem, leaf and whole plant biomass values were assessed for each plot based on the rate of fertilization with poultry manure and the cutting time. The results showed that irrespective of the cutting time, the largest plant height and diameter were obtained with 200 kg N ha-1 (160.37 ± 6.33 cm and 2.37 ± 0.33 cm, respectively). The biomass of stems, leaves and whole plants increased with the level of N fertilization. The highest biomass was obtained with cutting at 6 months and a fertilization rate of 200 kg N ha-1 (1.51 ± 0.01, 0.90 ± 0.01 and 2.41 ± 0.05 t MS/ha, respectively, for leaves, stems and whole plants). In conclusion, the application of poultry manure at a rate of 200 kg N ha-1 at the vegetative growth stage is optimal for Moringa oleífera production.Resumen El efecto de diferentes niveles de fertilización con guano de ave y tiempos de corte fueron evaluados sobre el crecimiento de Moringa oleífera. En un diseño factorial con seis niveles con fertilización de guano de ave (0, 50, 100, 150, 200 y 250 kg N ha-1) y tres tiempos de corte (4, 6 y 8 meses) con cuatro replicas fue utilizado. Después de un mes de siembra, se llevó a cabo la fertilización. En cada tiempo de corte, 20 plantas fueron colectadas por tratamiento para las mediciones de altura y diåmetro. La biomasa del tallo, hoja y planta entera de Moringa oleífera fue analizada por cada parcela dependiendo de su nivel de fertilización con guano de ave y su respectivo tiempo de corte. Los resultados mostraron que independiente del tiempo de corte, la mayor altura y diåmetro de la planta fue obtenida con 200 kg N ha-1. La biomasa del tallo, hoja y planta entera aumentó conforme el nivel de fertilización aumentó. La mejor biomasa se obtuvo en el corte a los 6 meses (1.51, 0.90 y 2.41 t MS ha-1 respectivamente para hojas, tallo y planta entera. En conclusión, la utilización de guano de ave a razón de 200 kg N ha-1 es la mås adecuada para el crecimiento de Moringa oleífera en estado vegetativo

    BucureÂști) ♩ 59 ♩ Nr

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    Several catanionic organogelators derived from 1,3 :2,4-bis-O-(p-aminobenzylidene

    Original Preparation of PEKK Dispersion for Coating by Transfer from a Chloroform Stable Dispersion to an Aqueous Stable Dispersion, by Emulsion/Solvent Evaporation

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    In this work, aqueous dispersions of PolyEtherKetoneKetone (PEKK) oligomers were obtained by an emulsion/dispersion solvent evaporation technique. The PEKK oligomers were synthesized by a Friedel–Crafts acylation with a number average degree of polymerization of 4. The synthesized PEKK oligomers had very good thermal stability and spontaneously formed a stable dispersion of swollen micrometric fibers in chloroform. After sonication of the chloroform dispersion in water in the presence of sodium dodecyl sulfate (SDS) and evaporation, we obtained aggregated particles with a mean diameter between 120 and 160 nm, decreasing linearly with the PEKK concentration. The most stable dispersions were obtained with 0.5% wt of surfactant and, at a fixed concentration of SDS, the stability decreased when the PEKK concentration was increased. The different dispersions of PEKK in water were very stable and, after water evaporation, formed homogeneous films for high-performance coating
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