12 research outputs found
Characterization of thermal, mechanical and hydration properties of novel films based on Saccharomyces cerevisiae biomass
Characterization of films made of Saccharomyces cerevisiae biomass was performed so as to better understand their properties. The treated yeast biomass, named HTH, was prepared by subsequent steps including a first homogenization, heat treatment and final homogenization. Glycerol was added as plasticizer and films were evaluated using different techniques to measure mechanical behaviour, thermal properties and water sorption. Temperature of maximum decomposition rate was found near 300 °C, while the gradually disappearance of amide II band (1543 cmâ1) occurred from 225 °C, identified by FTIR spectra of residues of thermally treated films by TGA. A glass transition at 64.5 ± 3.0 °C and two low energy endotherms at 61.2 ± 2.3 and 106.1 ± 0.7 °C were determined in completely dehydrated films without glycerol. When glycerol content was increased the glass transition temperature was shifted to lower values, a maximum elongation of 12% was reached, Young's modulus decreased from 88 to 9 MPa and the water uptake of films raised from 0.49 to 0.79 g H2O/g of dry matter. The characterization of yeast biodegradable films provided evidence of their properties for a potential future use in packaging industry. Industrial relevance: The development of biodegradable films based on yeast biomass carries many advantages to the food industry, such as, the possibility of using commercial pressed baker's yeast or an industrial residue from brewing industry, the use of a low-cost sources and the application of environmentally friendly procedures. The methodologies applied for the development of the film forming dispersion, high pressure homogenization and thermal treatment, are able to be scaled-up to an industrial level.Fil: Delgado, Juan Francisco. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa. Ărea IngenierĂa en Alimentos; ArgentinaFil: Peltzer, Mercedes Ana. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa. Ărea IngenierĂa en Alimentos; ArgentinaFil: Salvay, AndrĂ©s Gerardo. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa. Ărea IngenierĂa en Alimentos; ArgentinaFil: de la Osa, Orlando. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa. Ărea IngenierĂa en Alimentos; ArgentinaFil: Wagner, Jorge Ricardo. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa. Ărea IngenierĂa en Alimentos; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentin
Biobased Composites of Poly(Lactic Acid) Melt Compounded with Bacterial and Vegetal Nanocelluloses Incorporated through Different Strategies
In the current contribution, bacterial nanocellulose obtained from a by-product of Kombucha tea production and vegetal nanocellulose isolated from milled rice husks were employed as fillers of PLA-based composites prepared by intensive mixing followed by compression molding. Given the challenges associated with the incorporation of nanocellulosesâinitially obtained as aqueous suspensionsâinto melt compounding processes, and also with achieving a proper dispersion of the hydrophilic nanofillers within PLA, three different nanofibrils incorporation strategies were studied: i.e., direct mixing of dried milled nanocelluloses and PLA; masterbatching by solvent casting of native nanocelluloses followed by melt compounding; and masterbatching by solvent casting of acetylated nanocelluloses followed by melt compounding. Composites with varying filler content (from 0.5 wt.% to 7 wt.%) were characterized in terms of morphology, optical properties, and mechanical performance. Results revealed the relative suitability of each strategy employed to promote nanocelluloses dispersion within the PLA matrix. PLA/nanocellulose masterbatches prepared by solvent casting proved to be particularly useful for feeding the nanocelluloses into the processing equipment in a dry state with limited hornification. Acetylation also contributed to a better dispersion of both nanocelluloses within the PLA matrix, although no clear positive impact on the mechanical properties of the films was observed. Finally, filler loading played an important role in the filmsâ properties by increasing their stiffness while reducing their translucency.Fil: Bovi, Jimena. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Houssay. Instituto de TecnologĂa en PolĂmeros y NanotecnologĂa. Universidad de Buenos Aires. Facultad de IngenierĂa. Instituto de TecnologĂa en PolĂmeros y NanotecnologĂa; ArgentinaFil: Delgado, Juan Francisco. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Houssay. Instituto de TecnologĂa en PolĂmeros y NanotecnologĂa. Universidad de Buenos Aires. Facultad de IngenierĂa. Instituto de TecnologĂa en PolĂmeros y NanotecnologĂa; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa; ArgentinaFil: de la Osa, Orlando. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa; ArgentinaFil: Peltzer, Mercedes Ana. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Bernal, Celina Raquel. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Houssay. Instituto de TecnologĂa en PolĂmeros y NanotecnologĂa. Universidad de Buenos Aires. Facultad de IngenierĂa. Instituto de TecnologĂa en PolĂmeros y NanotecnologĂa; ArgentinaFil: Foresti, MarĂa Laura. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Houssay. Instituto de TecnologĂa en PolĂmeros y NanotecnologĂa. Universidad de Buenos Aires. Facultad de IngenierĂa. Instituto de TecnologĂa en PolĂmeros y NanotecnologĂa; Argentin
Biobased materials from microbial biomass and its derivatives
There is a strong public concern about plastic waste, which promotes the development of new biobased materials. The benefit of using microbial biomass for new developments is that it is a completely renewable source of polymers, which is not limited to climate conditions or may cause deforestation, as biopolymers come from vegetal biomass. The present review is focused on the use of microbial biomass and its derivatives as sources of biopolymers to form new materials. Yeast and fungal biomass are low-cost and abundant sources of biopolymers with high promising properties for the development of biodegradable materials, while milk and water kefir grains, composed by kefiran and dextran, respectively, produce films with very good optical and mechanical properties. The reasons for considering microbial cellulose as an attractive biobased material are the conformational structure and enhanced properties compared to plant cellulose. Kombucha tea, a probiotic fermented sparkling beverage, produces a floating membrane that has been identified as bacterial cellulose as a side stream during this fermentation. The results shown in this review demonstrated the good performance of microbial biomass to form new materials, with enhanced functional properties for different applications.Fil: Cottet, Agustina Celeste. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa; Argentina. Provincia de Buenos Aires. GobernaciĂłn. ComisiĂłn de Investigaciones CientĂficas; ArgentinaFil: RamĂrez Tapias, Yuly Andrea. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa; ArgentinaFil: Delgado, Juan Francisco. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa; ArgentinaFil: de la Osa, Orlando. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa; ArgentinaFil: Salvay, AndrĂ©s Gerardo. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa; ArgentinaFil: Peltzer, Mercedes Ana. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa; Argentin
CaracterizaciĂłn de algunos estados emocionales en pacientes con retinosis pigmentaria tĂpica en dos de sus estadios
The present investigation was conducted to characterize the emotional states in patients with typical retinitis pigmentary in its first two stages that were treated at the "Arnaldo Milian Castro" Surgical Hospital, the City of Santa Clara, Villa Clara province, between September 2011 and April 2012. It was left for both the methologic design research and for analysis of the results of joint paradigm; quantitative and qualitative data were linked in psychological research. Transversal descriptive study was conducted using a sample of 10 patients in each one of the first two stages of the disease from a simple random sampling probabilistic; Inclusion and exclusion criteria were established to form the samples. Information for the study was obtained from the application of different psychological tools of exploration. It was concluded that depression, followed by anxiety, predominates over the other emotional states studied in both groups, both had their impact mainly in the personal area of these subjects and an uncertain expectation of the future to find and significant degree of psychological involvement. The more strongly personally experienced emotional states were found in stage II of the disease closely related with its progression; also appeared more affected in their social relationships.La presente investigaciĂłn se realizĂł con el objetivo de caracterizar los estados emocionales en pacientes con retinosis pigmentaria tĂpica en sus dos primeros estadios que fueron atendidos en el Hospital ClĂnico QuirĂșrgico âArnaldo MiliĂĄn Castroâ, de la Ciudad de Santa Clara, Provincia de Villa Clara, entre septiembre de 2011 y abril de 2012. Se partiĂł tanto para el diseño metodolĂłgico como para el anĂĄlisis de los resultados del paradigma mixto de investigaciĂłn; se vincularon datos cuantitativos y cualitativos en la investigaciĂłn psicolĂłgica. Se realizĂł un estudio de tipo descriptivo transversal en una muestra de 10 pacientes de cada uno de los dos primeros estadios de la enfermedad a partir de un muestreo de tipo probabilĂstico aleatorio simple; se establecieron criterios de inclusiĂłn y exclusiĂłn para conformar las muestras. La informaciĂłn para el estudio se obtuvo de la aplicaciĂłn de distintos instrumentos psicolĂłgicos de exploraciĂłn. Se concluyĂł que la depresiĂłn, seguida de la ansiedad, predomina por encima de los demĂĄs estados emocionales estudiados en ambos grupos, que ambas tuvieron su repercusiĂłn, principalmente, en el ĂĄrea personal de estos sujetos y que se encontraron una expectativa incierta del futuro y un grado importante de afectaciĂłn psicolĂłgica. Los estados emocionales mĂĄs fuertemente vivenciados se encontraron en el estadio II de la enfermedad estrechamente relacionados con su progresiĂłn; apareciĂł tambiĂ©n mayor afectaciĂłn en sus relaciones sociales
Red de torres meteorológicas de referencia para el programa eólico cubano. Resultados preliminares del estudio del viento con fines energéticos
Ponencia presentada en: XXX Jornadas CientĂficas de la AME y el IX Encuentro Hispano Luso de MeteorologĂa celebrado en Zaragoza, del 5 al 7 de mayo de 2008
Measurement of W+Wâ production in association with one jet in protonâproton collisions at sqrt(s) = 8TeV with the ATLAS detector
The production of W boson pairs in association with one jet in pp collisions at View the MathML sources=8 TeV is studied using data corresponding to an integrated luminosity of 20.3 fbâ1 collected by the ATLAS detector during 2012 at the CERN Large Hadron Collider. The cross section is measured in a fiducial phase-space region defined by the presence of exactly one electron and one muon, missing transverse momentum and exactly one jet with a transverse momentum above 25 GeV and a pseudorapidity of |η|<4.5|η|<4.5. The leptons are required to have opposite electric charge and to pass transverse momentum and pseudorapidity requirements. The fiducial cross section is found to be View the MathML sourceÏWWfid,1-jet=136±6(stat)±14(syst)±3(lumi) fb. In combination with a previous measurement restricted to leptonic final states with no associated jets, the fiducial cross section of WW production with zero or one jet is measured to be View the MathML sourceÏWWfid,â€1-jet=511±9(stat)±26(syst)±10(lumi) fb. The ratio of fiducial cross sections in final states with one and zero jets is determined to be 0.36±0.050.36±0.05. Finally, a total cross section extrapolated from the fiducial measurement of WW production with zero or one associated jet is reported. The measurements are compared to theoretical predictions and found in good agreement
Effect of Hygrothermal History on Water and Mechanical Properties of Glass/Vinylester Composites
The effects of hygrothermal aging on the mechanical and viscoelastic properties of vinylester (VE)/unidirectional glass-fiber composites are reported. The studies are done by means of a dynamometer (INSTRON) and a dynamic mechanical thermal analyzer (Perkin Elmer). The studies are carried out at three different temperatures: 20, 40, and 60 C. The adhesion between the fibers and matrix is studied by scanning electron microscopy (SEM) microphotographs. Flexural strength, flexural modulus, storage modulus in the glass state (Tg - 50 K), in rubber state (Tg + 50 K), and the glass transition temperatures are also investigated. These parameters are determined in the case of the matrix and composites materials, for the initial and final states. The diffusion coefficients are calculated by using the simplest Fick's equation.Fil: de la Osa, Orlando. Universidad Nacional de Quilmes; ArgentinaFil: Alvarez, Vera Alejandra. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y TecnologĂa de Materiales. Universidad Nacional de Mar del Plata. Facultad de IngenierĂa. Instituto de Investigaciones en Ciencia y TecnologĂa de Materiales; ArgentinaFil: VĂĄzquez, AnalĂa. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Houssay. Instituto de TecnologĂa en PolĂmeros y NanotecnologĂa. Universidad de Buenos Aires. Facultad de IngenierĂa. Instituto de TecnologĂa en PolĂmeros y NanotecnologĂa; Argentin
Use of Residual Yeast Cell Wall for New Biobased Materials Production: Effect of Plasticization on Film Properties
The use of renewable resources to develop food contact materials, such as proteins or polysaccharides, and the use of industrial residues for alternative applications are trending topics for researchers and the industry. Yeast cell wall (YCW) is a very rich waste from the yeast extract industry. Due to this, the aim of this work is to develop new biodegradable films based on residual YCW and the study of the effect of plasticization on films properties. Residual YCW was used as base matrix and different concentrations of glycerol (0, 15, 25 and 35 wt%) were tested to obtain casted films. Homogeneous and yellow-brownish films, which allow seeing through them, were obtained from the YCW. Total soluble matter demonstrated that glycerol enhanced solubility of films but glycerol was retained in the polymer matrix. TGA studies indicated that YCW films exhibited substantial degradation at temperatures above 180 °C. FTIR spectra of the casted films were representative of yeast cell wall material and SEM photographs showed that cell wall maintained their shape after film formation. As expected, Youngâs modulus and tensile strength values were decreased with the increasing amount of glycerol. However, elongation at break was not increased further with higher concentration of plasticizer and the addition of 15 wt% of glycerol seemed to be enough to improve mechanical properties. The linear increment of water vapour permeability with glycerol concentration was produced by the increase in water solubility in the film. Therefore, based on solubility in water, mechanical, and barrier properties, it is possible to propose yeast cells residues as film-forming material for biodegradable film developments.Fil: Peltzer, Mercedes Ana. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa; ArgentinaFil: Salvay, A.G.. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa; ArgentinaFil: Delgado, Juan Francisco. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: de la Osa, Orlando. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa; ArgentinaFil: Wagner, Jorge Ricardo. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentin
Impact of the film-forming dispersion pH on the properties of yeast biomass films
BackgroundYeast biomass, mainly composed by proteins and polysaccharides (mannans and ÎČâglucans), has been proposed to develop films. pH can affect the solubility of polysaccharides, the structure of the cellâwall and the interactions between proteins. Considering the potential impact of these effects, the pH of yeast filmâforming dispersions was studied from 4 to 11.ResultsIn tensile tests, samples increased their elongation by increasing pH, from 7â±â2% (pHâ4) to 29â±â5% (pHâ11), but YoungÂŽs modulus was not significantly modified. Regarding thermal degradation, the maximum degradation rate temperature was shifted 46 °C from pHâ4 to 11. Differences in water vapour permeability, colour, opacity and roughness of films were also found. According to the results of differential protein solubility assay, at pHâ4 hydrophobic interactions and hydrogen bonding were promoted but, at pHâ11 disulphide bonds were benefited, in addition to partial ÎČâglucan dissolution and breakâup of the alkaliâsensitive linkage in molecules from the cell wall.ConclusionResults let to conclude that filmâfunctional characteristics were greatly benefited at pHâ11 in comparison to the regular pH of dispersion (pHâ6). These results could help to understand and select the pH conditions to enhance the desired properties of yeast biomass films.Fil: Delgado, Juan Francisco. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa. Ărea IngenierĂa en Alimentos; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Houssay. Instituto de TecnologĂa en PolĂmeros y NanotecnologĂa. Universidad de Buenos Aires. Facultad de IngenierĂa. Instituto de TecnologĂa en PolĂmeros y NanotecnologĂa; ArgentinaFil: Salvay, AndrĂ©s Gerardo. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa. Ărea IngenierĂa en Alimentos; ArgentinaFil: de la Osa, Orlando. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa. Ărea IngenierĂa en Alimentos; ArgentinaFil: Wagner, Jorge Ricardo. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa. Ărea IngenierĂa en Alimentos; ArgentinaFil: Peltzer, Mercedes Ana. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa. Ărea IngenierĂa en Alimentos; Argentin
Development of innovative biodegradable films based on biomass of Saccharomyces cerevisiae
Biodegradable alternatives to petroleum-based polymers are being developed for food packaging. Saccharomyces cerevisiae has been widely used for the production of fermented beverages and leavened foods. In this work, the application of high pressure homogenisation and a thermal treatment to the yeast biomass was studied to develop biodegradable films. The highest dispersibility indexes of protein (84.5 ± 3.3%), carbohydrates (24.3 ± 1.1%), RNA (40.6 ± 0.9%) and soluble solids released were found at high homogenisation pressure (125 MPa). Combinations of one or two homogenisations and a thermal treatment at 90 °C during 20 minutes were applied and dispersions were fully characterised, focusing on their film-forming capacity. The best combination was homogenisation, heat treatment and a further homogenisation, since it produced films that presented good attributes, great continuity and homogeneity without small cracks. However, hydration of films was increased from 0.31 to 0.48 gH2O/g.d.m with the number of homogenisation processes applied. Results revealed that yeast biomass is a viable source to be used in biodegradable films. Industrial relevance Saccharomyces cerevisiae yeasts have many applications in food industry. The development of biodegradable films based on yeast biomass carries many advantages such as, the possibility of using commercial pressed baker's yeast or an industrial residue from brewing industry, the use of a low-cost sources and the application of environmentally friendly procedures. The methodologies applied for the development of the film forming dispersion, high pressure homogenisation and thermal treatment, are able to be scaled-up to an industrial level.Fil: Delgado, Juan Francisco. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa; ArgentinaFil: Sceni, Paula. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa; ArgentinaFil: Peltzer, Mercedes Ana. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa; ArgentinaFil: Salvay, AndrĂ©s Gerardo. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa; ArgentinaFil: de la Osa, Orlando. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa; ArgentinaFil: Wagner, Jorge Ricardo. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologĂa; Argentin