Antibacterial activity of gelatin/copper (II)-exchanged montmorillonite films

Cu (II) - exchanged montmorillonite (Cu2+MMt) was prepared, characterized and introduced into a bovine gelatin (Ge) matrix via a dissolution-intercalation method to get antibacterial nanocomposite films. The maximum amount of exchanged cation did not exceed the cation exchange capacity of the pristine montmorillonite (Na+MMt), as assessed by energy dispersive X-ray (EDX) spectroscopy. Cu2+MMt showed antibacterial activity in vitro against Escherichia coli O157:H7 (Gram-negative) and Listeria monocytogenes (Gram-positive) as revealed by the agar disc-diffusion assay. The dispersion of clays in Ge films was monitored by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). Blending gelatin with 5% w/w of clay increased the tensile strength of the nanocomposite films in around 280% while the elongation at break and the water vapor permeability decreased in about 42 and 30%, respectively, regardless of the cation in clay. The Ge/Cu2+MMt film exhibited antibacterial effectiveness against both pathogens tested under the same conditions, demonstrating a stronger effect on L. monocytogenes than on E. coli O157:H7, since the cell wall of the latter differs significantly and such difference could influence their vulnerability and response to the active films. Therefore, the incorporation of low clay levels as a vehicle for copper ions into gelatin matrix has demonstrated to be a good method for developing functional materials that can be potentially applied to the design of food contact items.Fil: Martucci, Josefa Fabiana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Ruseckaite, Roxana Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

New methods to detect multiple sclerosis

This paper describes multifocal visual evoked potentials (mfVEPs) recorded to different levels of temporal sparseness. It presents the usefulness and diagnostic value of mfVEPs in multiple sclerosis (MS) and optic neuritis (ON). The paper also discusses the usefulness of frequency doubling (FD) illusion and the effect of binocularity in Normal and MS study groups

New Flexible Models and Design Construction Algorithms for Mixtures and Binary Dependent Variables

This thesis discusses new mixture(-amount) models, choice models and the optimal design of experiments. Two chapters of the thesis relate to the so-called mixture, which is a product or service whose ingredients’ proportions sum to one. The thesis begins by introducing mixture models in the choice context and develops new optimal design construction algorithms for choice experiments involving mixtures. Building further, varying the total amount of a mixture, and not only its ingredient proportions, might also affect the response. The models that exist for mixture-amount data date back to the 1980s and have several drawbacks, which limit their usefulness for these data. Therefore, the next chapter in this thesis develops new flexible models for mixture-amount data, which are based on so-called Gaussian processes. The last chapter builds on the aforementioned model and, using revealed preference data on green vehicle purchases in France, presents a new choice model that accounts for latent environmental consciousness, where environmental consciousness is allowed to have a flexible heterogeneous impact on the vehicle choice across the population

Human scotopic dark adaptation: Comparison of recoveries of psychophysical threshold and ERG b-wave sensitivity

We have compared the time course of dark adaptation of the human scotopic visual system, measured psychophysically and from the b-wave of the electroretinogram (ERG), for bleaches ranging from a few percent to near total. We also measured light adaptation, in order to apply a "Crawford transformation" to convert the raw measurements of dark adaptation into equivalent background intensities. For both the "psychophysical threshold equivalent" intensity and the "ERG b-wave sensitivity equivalent" intensity, the equivalent background declined over much of its range with an "S2" component, though with somewhat different slopes of -0.36 (psychophysical) and -0.22 (ERG) log10 unit min-1, respectively. In addition, the magnitude of the equivalent background was approximately 1 log10 unit lower in the psychophysical experiments than in the ERG experiments. Despite these differences, the two approaches extract a common time course for the decline in level of free opsin following moderately large bleaches. We conclude that the recovery of psychophysical scotopic visual threshold over the S2 region reflects events that are present by the stage of the first synapse of rod vision, stemming ultimately from the presence of unregenerated opsin in the rod outer segments

Enhancing Water Resistance, Tensile Properties and UV-Shielding Capacity of Bovine Gelatin Films Modified with Epoxidized Soybean Oil and Glyoxal during Processing

The present work is focused on the use of epoxidized soybean oil (ESO, 10 wt%) as hydrophobizing additive, glycerol as plasticizer (Gly, 30 wt.%),and glyoxal (GLX, 2 wt%) as low-toxicity cross-linking agent to endow bovine gelatin (BGe) films with improved moisture-related and UV-light barrier properties. Therefore, we aimed to investigate the effect of such modifications on the physicomechanical and structural properties of the ob-tained gelatin films. Modification was produced during intensive mixing and hot-press molding as a more environmentally sound and less time-con-suming processing method. ESO improved moderately the moisture content (MC) and water vapor permeability (WVP) of BGe film by 19% and 29%, respectively, but the total solubility of BGe-10ESO film evidenced the inability of ESO to induce covalent cross-linking. When GLX was add-ed to the BGe-10ESO formulation, several target film properties were upgraded; the film kept about 78% of its weight after 24 h of soaking in water, WVP improved by 56.8%, the tensile strength (TS) increased 48% while the stretching ability dropped in about 41%. The significant reduction in available free amino groups, from 100% (control) up to 21.9%, together with the increased color from light yellow to light orange confirmed that amino groups in BGe were involved in imine-based cross-linked structure when treated with glyoxal. Further, the high blocking ability of BGe-10ESO-2GLX film against UV-radiation may be useful in delaying UV-induced lipid oxidation when it is placed in contact with foods.Fil: González Granados, María Lucía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Martucci, Josefa Fabiana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Ruseckaite, Roxana Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Bayesian D-Optimal Choice Designs for Mixtures

__Abstract__ Consumer products and services can often be described as mixtures of ingredients. Examples are the mixture of ingredients in a cocktail and the mixture of different components of waiting time (e.g., in-vehicle and out-of-vehicle travel time) in a transportation setting. Choice experiments may help to determine how the respondents' choice of a product or service is affected by the combination of ingredients. In such studies, individuals are confronted with sets of hypothetical products or services and they are asked to choose the most preferred product or service from each set. However, there are no studies on the optimal design of choice experiments involving mixtures. We propose a method for generating an optimal design for such choice experiments. To this end, we first introduce mixture models in the choice context and next present an algorithm to construct optimal experimental designs, assuming the multinomial logit model is used to analyze the choice data. To overcome the problem that the optimal designs depend on the unknown parameter values, we adopt a Bayesian D-optimal design approach. We also consider locally D-optimal designs and compare the performance of the resulting designs to those produced by a utility-neutral (UN) approach in which designs are based on the assumption that individuals are indifferent between all choice alternatives. We demonstrate that our designs are quite different and in general perform better than the UN designs

Sickness certification of workers compensation claimants by general practitioners in Victoria, 2003-2010

Objective: To examine patterns of the sickness certification of workers compensation claimants by general practitioners in Victoria, Australia, by nature of injury or illness. Design, setting and patients: Retrospective analysis of Victorian workers compensation data for all injured and ill workers with an accepted workers compensation claim between 2003 and 2010. Main outcome measures: Type (unfit for work, alternative duties, or fit for work) and duration of initial medical certificates relating to workers compensation claims that were issued by GPs, in six categories of injury and illness. Results: Of 124 424 initial medical certificates issued by GPs, 74.1% recommended that workers were unfit for work and 22.8% recommended alternative duties. Unfit-for-work certificates were issued to 94.1% of workers with mental health conditions, 81.3% of those with fractures, 79.1% of those with other traumatic injuries, 77.6% of those with back pain and strains, 68.0% of those with musculoskeletal conditions and 53.0% of those with other diseases. Alternative-duties certificates were significantly longer in duration than unfit-for-work certificates in all injury and illness categories (P<0.001) but certificates for workers with musculoskeletal injuries and diseases, back pain and strains and other traumatic injuries were of lesser duration than those for workers with fractures, mental health conditions and other diseases. Conclusion: The high proportion of medical certificates recommending complete absence from work presents major challenges in terms of return to work, labour force productivity, the viability of the compensation system, and long-term social and economic development. There is substantial variation in the type and duration of medical certificates issued by GPs. People with mental health conditions are unlikely to receive a certificate recommending alternative duties. Further research is required to understand GP certification behaviour

Estudio del envejecimiento de películas activas basadas en gelatina de pescado y carvacrol

La gelatina es una proteína de origen animal que se obtiene de la desnaturalización del colágeno del tejido conectivo de mamíferos y peces. La gelatina se ha utilizado intensamente en el desarrollo de películas para el envasado activo de alimentos debido a su naturaleza renovable y calificación de GRAS (FDA), su capacidad formadora de películas, su procesabilidad, su excelente barrera a los gases y aromas y sus adecuadas propiedades mecánicas a humedades relativas bajas o intermedias1 . Desde el punto de vista tecnológico, el uso de las películas de gelatina como reemplazo de las derivadas de polímeros sintéticos dependerá fuertemente de asegurar la invariabilidad de sus propiedades funcionales con el tiempo ya que las películas proteicas, en estado vítreo, sufren de envejecimiento químico y físico2 . El envejecimiento químico está asociado a reacciones químicas que pueden tener lugar con el tiempo, como la formación de agregados, enlaces disulfuro, etc2,3. Los cambios físicos se asocian con la evolución desde un estado vítreo de no equilibrio hacia el de equilibrio acompañado por reordenamientos moleculares2,3,5 que pueden provocar la migración de plastificante, antioxidante u otros aditivos, lo que impactará en la estabilidad de las propiedades finales de las películas a largo término. En el presente trabajo se propone estudiar el efecto del tiempo de almacenamiento sobre las propiedades funcionales de películas activas de gelatina de pescado aditivadas con carvacrol.Fil: Neira Hazime, Laura Margarita. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Martucci, Josefa Fabiana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Ruseckaite, Roxana Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Rheological studies on glycerol plasticized gelatin and Its blends with epoxidized soybean oil

Blends of gelatin (Ge) plasticized with varying amounts of glycerol (Gly), buffer solution pH 10 and epoxidized soybean oil (ESO) to enhance hydrophobicity were prepared by mixing and injection-molding. Blends were characterized by rheological tests and microscopy to select optimal conditions for scaling up their processing. The effect of each component on rheological response was analyzed using parallel plate geometry. Coating of gelatin specimens with PDMS during rheological tests led to reliable and reproducible results since water evaporation was prevented. A gradual increment in ESO concentration led to blends with increased degree of phase separation, as evidenced by optical and confocal microscopy. Limited compatibility between ESO and Ge increased viscosity at high ESO levels, but up to 10% Gly could be replaced with ESO without a significant variation of rheological behavior.Fil: Ciannamea, Emiliano Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Castillo, Luciana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería Química; ArgentinaFil: Ruseckaite, Roxana Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Barbosa, Silvia Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería Química; Argentin