Concepción, Chile
Concepción, Chile

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Chaigneau A.,Laboratoire Doceanographie Et Of Climatologie Experimentation Et Analyse Numerique | Chaigneau A.,Instituto Del Mar Of Peru | Chaigneau A.,Laboratoire dEtudes en Geophysique et Oceanographie Spatiale | Le Texier M.,CNRS Institute of Fluid Mechanics of Toulouse | And 3 more authors.
Journal of Geophysical Research: Oceans | Year: 2011

The mean vertical structure of mesoscale eddies in the Peru-Chile Current System is investigated by combining the historical records of Argo float profiles and satellite altimetry data. A composite average of 420 (526) profiles acquired by Argo floats that surfaced into cyclonic (anticyclonic) mesoscale eddies allowed constructing the mean three-dimensional eddy structure of the eastern South Pacific Ocean. Key differences in their thermohaline vertical structure were revealed. The core of cyclonic eddies (CEs) is centered at ∼150 m depth within the 25.2-26.0 kg m-3 potential density layer corresponding to the thermocline. In contrast, the core of the anticyclonic eddies (AEs) is located below the thermocline at ∼400 m depth impacting the 26.0-26.8 kg m-3 density layer. This difference was attributed to the mechanisms involved in the eddy formation. While intrathermocline CEs would be formed by instabilities of the surface equatorward coastal currents, the subthermocline AEs are likely to be shed by the subsurface poleward Peru-Chile Undercurrent. In the eddy core, maximum temperature and salinity anomalies are of ±1°C and ±0.1, with positive (negative) values for AEs (CEs). This study also provides new insight into the potential impact of mesoscale eddies for the cross-shore transport of heat and salt in the eastern South Pacific. Considering only the fraction of the water column associated with the fluid trapped within the eddies, each CE and AE has a typical volume anomaly flux of ∼0.1 Sv and yields to a heat and salt transport anomaly of ±1-3 × 1011 W and ±3-8 × 103 kg s-1, respectively. Copyright 2011 by the American Geophysical Union.

Ciudad G.,University of the Frontier | Rubilar O.,University of the Frontier | Azocar L.,University of the Frontier | Toro C.,Barrio Universitario | And 4 more authors.
Journal of Bioscience and Bioengineering | Year: 2014

Microalgae can produce and contain lipids, proteins and carbohydrates, which can be extracted and marketed as potential novel added-value bio-products. However, microalgae cell wall disruption is one of the most important challenges involved while processing this type of biomass. In this context, white-rot fungi, responsible for the biodegradation of lignin present in wood due to non-specific extracellular enzymes, could be applied for promoting microalgae cell wall degradation. Therefore, the aim of this study was to evaluate the use of an enzymatic extract produced by the white-rot fungi Anthracophyllum discolor as a biotechnological tool for Botryococcus braunii cell wall disruption. The fungus was inoculated in wheat grains and manganese peroxidase (MnP) activity was monitored while obtaining the enzymatic extract. Then, cell wall disruption trials with different MnP activity were evaluated by the biochemical methane potential (BMP). In relation to cell wall disruption, it was observed that the optimal value was obtained with enzymatic concentration of 1000U/L with a BMP of 521mL CH4/g VS. Under these conditions almost 90% of biomass biodegradability was observed, increasing in 62% compared to the microalgae without treatment. Therefore, the results indicate that enzymes secreted by A. discolor promoted the attack of the different cell wall components finally weakening it. Therefore, the application of this treatment could be a promissory biotechnological approach to decrease the energetic input required for the cell wall disruption step. © 2013 The Society for Biotechnology, Japan.

Cancino J.,University of Concepción | Cancino J.,Barrio Universitario | Acuna E.,University of Concepción | Espinosa M.,University of Concepción
Forest Science | Year: 2013

This article presents a general conceptual framework for seven methods of estimating the height to a given age by stem analysis, which involves estimates of periodical annual increment in height. To estimate the height, a fraction of the periodical increment in height, which is cumulated in a time fraction of the respective period, is assigned to every hidden tip. Traditional methods of height estimation in stem analysis can be grouped into two broad sets, depending on how the time fraction associated with every hidden tip is determined. By combining time fractions from both groups, two mixed methods were derived and compared with traditional methods to determine the most advantageous method under variations in the crosscut intensity and regularity along the stem and variations in the regularity of current annual increments in total height and stem radius throughout the tree's life. The combined methods were more accurate than traditional methods when sampling schemes that involve long distances between crosscuts are carried out and especially when sampling combines variable distances between crosscuts. If a sample were available, simultaneously combining crosscuts at varying distances taken from trees having varying degrees of irregularities in stem radius and height increments, the combined methods would surpass traditional methods in accuracy. © 2013 by the Society of American Foresters.

Uribe M.E.,University of Concepción | Uribe M.E.,Barrio Universitario | Delaveau C.,University of Concepción | Paredes K.,University of Concepción | And 2 more authors.
Gayana - Botanica | Year: 2012

The in vitro germination of seeds of Vestia foetida (Ruiz et Pav.) Hoffmanns. and their multiplication was performed. A 20% in vitro germination was obtained. The best proliferation medium was MS supplemented with BAP (1.0 mg L-1) plus AIB (0.01 mg L-1), with an average of 1.7 new axillary buds per microshoot after two subcultures. © 2012, Universidad de Concepcion. All rights reserved.

Acevedo A.,Pontifical Catholic University of Valparaíso | Acevedo A.,Barrio Universitario | Aroca G.,Pontifical Catholic University of Valparaíso | Aroca G.,Barrio Universitario | And 2 more authors.
PLoS ONE | Year: 2014

Scheffersomyces stipitis is a yeast able to ferment pentoses to ethanol, unlike Saccharomyces cerevisiae, it does not present the so-called overflow phenomenon. Metabolic features characterizing the presence or not of this phenomenon have not been fully elucidated. This work proposes that genome-scale metabolic response to variations in NAD(H/+) availability characterizes fermentative behavior in both yeasts. Thus, differentiating features in S. stipitis and S. cerevisiae were determined analyzing growth sensitivity response to changes in available reducing capacity in relation to ethanol production capacity and overall metabolic flux span. Using genome-scale constraint-based metabolic models, phenotypic phase planes and shadow price analyses, an excess of available reducing capacity for growth was found in S. cerevisiae at every metabolic phenotype where growth is limited by oxygen uptake, while in S. stipitis this was observed only for a subset of those phenotypes. Moreover, by using flux variability analysis, an increased metabolic flux span was found in S. cerevisiae at growth limited by oxygen uptake, while in S. stipitis flux span was invariant. Therefore, each yeast can be characterized by a significantly different metabolic response and flux span when growth is limited by oxygen uptake, both features suggesting a higher metabolic flexibility in S. cerevisiae. By applying an optimization-based approach on the genome-scale models, three single reaction deletions were found to generate in S. stipitis the reducing capacity availability pattern found in S. cerevisiae, two of them correspond to reactions involved in the overflow phenomenon. These results show a close relationship between the growth sensitivity response given by the metabolic network and fermentative behavior. © 2014 Acevedo et al.

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