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8841
Oceanographic conditions west of the Baja California coast, 2002-2003: A weak El Niño and subarctic water enhancement
Published in Ciencias Marinas (2005)Fuente: Redalyc · Ciencias MarinasTipo de material: Artículo científicoDescripción: Oceanographic conditions in the Pacific waters off Baja California are described for the period 2002–2003. Anomalies in the temperature-salinity relationships were observed from October 2002 to April 2003, with a clear contribution of low salinity and low temperature subarctic water in the upper 100 m of the water column. Below 100 m, physical data suggested weak El Niño conditions. Weakened or poleward winds were not observed. The pelagic ecosystem during the intrusion of subarctic waters showed strong seasonal changes, with localized centers of high chlorophyll and zooplankton in July 2002, followed by a strong decrease in the following autumn and winter seasons. Both chlorophyll and zooplankton rebounded in April 2003, but zooplankton showed a stronger onshore-offshore gradient. There was no strong biological signal. The zooplankton taxa that showed an increase during El Niño 2002–2003 were salps and chaetognaths. The increase of salps did not appear to be related to this event, due to their seasonal occurrence limited to the northern region. In contrast the increase of chaetognaths presented a similar pattern to that observed in El Niño 1997–1998. En este trabajo se describen las condiciones oceanográficas del Océano Pacífico frente a Baja California durante el periodo 2002–2003. De octubre de 2002 a abril de 2003 se observaron relaciones anómalas entre la temperatura y la salinidad debidas a la fuerte presencia de agua de origen subártico, con baja salinidad y baja temperatura, en los 100 m superiores de la columna de agua. Por debajo de los 100 m de profundidad los datos físicos sugirieron condiciones que indican la presencia de un evento El Niño débil. Durante el periodo de estudio no se observó una disminución en los vientos dominantes o vientos con dirección hacia el polo. El ecosistema pelágico mostró fuertes cambios estacionales debidos a la intrusión de agua subártica, con zonas de alta clorofila y zooplancton en julio de 2002, con un fuerte decremento durante el otoño e invierno siguientes. Tanto la clorofila como el zooplancton resurgieron en abril de 2003, con un mayor gradiente costa-océano en el zooplancton. No se presentó una fuerte señal biológica durante el período. Los grupos de zooplancton que mostraron un incremento durante El Niño 2002–2003 fueron las salpas y los quetognatos. El incremento de salpas no parece estar asociado al evento, ya que su incidencia fue estacional y restringida a la región norte. En cambio el incremento en quetognatos presentó un patrón similar al de El Niño 1997–1998.Acceso al recurso -
8842
Estructura de los mantos de rodolitos de 4 a 55 metros de profundidad en la costa sur del estado de Espírito Santo, Brasil
Published in Ciencias Marinas (2007)Fuente: Redalyc · Ciencias MarinasTipo de material: Artículo científicoDescripción: Rhodoliths are one of the most extensive benthic communities of the Brazilian continental shelf, but their structure is poorly known. The richest marine flora of Brazil´ s coastal zone is found in Espírito Santo State and its diversity has been partly associated with the presence of extensive areas of rhodoliths, extending from the intertidal zone to 120 m across the continental shelf. One species of kelp, Laminaria abyssalis, is endemic to this area and occurs between 45 and 120 m depth. Our objective was to determine the density and physical dimensions of the superficial rhodoliths between 4 and 55 m depth in the southern region of Espírito Santo State. The study area was 3 to 45 km offshore. Samples were obtained in 2004 and 2005 by Scuba diving in three depth zones: 4–18 m, 25–30 m and 50–55 m. Transect lines and video images were used to determine rhodolith density. The diameter and sphericity of at least 60 individuals from each zone were measured. Rhodolith size increased and density decreased from the shallow to the deeper zones. Spheroidal was the typical shape throughout the depth zones. Five rhodolith-forming genera were identified: Lithothamnion, Lithophyllum, Hydrolithon, Neogoniolithon and Sporolithon. Epibenthic biomass and species richness over the rhodolith bed in the shallow zone was lowest in winter, likely the result of disturbance caused by typical winter storms. Changes in light and temperature are probably the most important factors in the changes observed in the rhodolith beds from the deepest zones. Los mantos de rodolitos son de las comunidades bentónicas más extensas de la plataforma continental brasileña, pero su estructura es pobremente conocida. La región de flora marina más rica de la zona costera de Brasil está ubicada en el estado de Espírito Santo y su diversidad ha sido parcialmente asociada con la presencia de amplias áreas de rodolitos, que se extienden desde la zona intermareal hasta 120 m de profundidad sobre la plataforma continental. Una especie de alga marina, Laminaria abyssalis, es endémica de esta zona y se encuentra entre 45 y 120 m de profundidad. En este trabajo se determinó la densidad y las dimensiones físicas de los rodolitos superficiales entre 4 y 55 m de profundidad en la región sur del estado de Espírito Santo. El área de estudio está a una distancia de 3 a 45 km de la costa. Las muestras fueron recolectadas en 2004 y 2005 por buceo autónomo en tres rangos de profundidad: 4–18 m, 25–30 m y 50–55 m. Para determinar la densidad de los rodolitos se utilizaron líneas de transectos e imágenes de video. Se midieron los diámetros y la esfericidad de por lo menos 60 individuos de cada rango de profundidad. Se observó un incremento en la talla de los rodolitos así como una reducción en su densidad de la zona superficial a la más profunda. La forma típica en todas las profundidades fue la esférica. Se identificaron cinco géneros de especies formadoras de rodolitos: Lithothamnion, Lithophyllum, Hydrolithon, Neogoniolithon y Sporolithon. La biomasa epibéntica y la riqueza de especies sobre el manto de rodolitos en la zona más somera fue menor en invierno, probablemente debido a la perturbación causada por las tormentas invernales típicas. Las variaciones en la luz y la temperatura podrían ser los factores más importantes en los cambios observados en los mantos de rodolitos de las zonas más profundas.Acceso al recurso -
8843
Age models, accumulation rates, and grain size distributions of sediment cores from the northern subtropical Atlantic
Published 1981Fuente: PANGAEATipo de material: Dataset Open AccessAcceso al recurso -
8844
Effects of medicinal plants Origanum vulgare L. and Aloe vera on immune system of rainbow trout (Oncorhynchus mykiss)
Published 2014Fuente: AquaDocs / OceanDocsTipo de material: Recurso Open AccessAcceso al recurso -
8845
Geologic-hydrologic setting and surface sedimentology in the Persian Gulf
Published 1971Fuente: PANGAEATipo de material: Dataset Open AccessAcceso al recurso -
8846
La ictiofauna de Bahía San Blas (Provincia de Buenos Aires) y su relación con la dinámica de las pesquerías deportiva y artesanal.
Published 2011Fuente: AquaDocs / OceanDocsTipo de material: Recurso Open AccessAcceso al recurso -
8847
Fractal Correction Engine Applied to the Casimir Effect: Pi-Curvature Analysis of Quantum Vacuum Fluctuations
Published 2026Fuente: ZenodoTipo de material: Recurso digitalAcceso al recurso -
8848
N-K MASTER COMPUTER v17.0 — THE COMPLETE THERMAL CONDUCTIVITY UNIFICATION From First Principles: Derivation of the Wiedemann-Franz Law, Thermal Transport in Pure Metals and Alloys,...
Published 2026Fuente: ZenodoTipo de material: Recurso digitalAcceso al recurso -
8849
BIG DATA ANALYTICS TRANSFORMATION STRATEGY
Published 2025Fuente: ZenodoTipo de material: Recurso digitalAcceso al recurso -
8850
On the interpretation of short-period fluctuations in the thermocline obtained from a towed sensor
Published in Ciencias Marinas (1997)Fuente: Ciencias MarinasTipo de material: Artículo científicoDescripción: Se presentan algunas consideraciones relacionadas con la interpretación de los datos de las oscilaciones de la temperatura en la termoclina obtenidos con ayuda de un sensor en movimiento. En un modelo sencillo de relación de dispersión para ondas lineales internas con una disminución de energía en el espectro, isotrópica en cuanto a la dirección y uniforme por la frecuencia, se muestra que con determinadas velocidades de remolque del sensor es posible la aparición de un pico ficticio de densidad espectral en el espectro de frecuencias medido. También se analizan los resultados del estudio de la dependencia de la densidad espectral en los espectros de las ondas internas con respecto a la velocidad de movimiento del sensor, el carácter de la disminución de la energía y el número de onda para condiciones hidrológicas específicas. Se discute como evitar o disminuir las deformaciones Doppler en los espectros medidos. Aspects related to the interpretation of data from temperature oscillations in the thermocline obtained from a towed sensor are presented. A simple model of dispersion relation for linear internal waves with a decrease in energy in the spectrum, isotropic with regard to direction and uniform in frequency, shows that, at determined tow speeds of the sensor, a fictitious spectral density peak may appear in the frequency spectrum measured. The results of the study on the dependency of the spectral density in the interna1 wave spectra with respect to the tow speed of the sensor, the nature of the decrease in energy and wave number for specific hydrological conditions are also analyzed. How to avoid or decrease Doppler deformations in the spectra measured is discussed.Acceso al recurso -
8851
Efecto del estrés en la respuesta ecofisiológica de la galleta de mar Dendraster excentricus en el noroeste de México
Published in Ciencias Marinas (2014)Fuente: SIBUMAR · Ciencias MarinasTipo de material: LibroDescripción: In the Mexican Pacific, Dendraster excentricus, a common estuarine echinoderm, is subject to daily environmental variations in tidal fluxes. Little is known about its ecophysiological response when individuals are exposed to temperature and oxygen changes. This study evaluates their thermal stress response under normal and reduced oxygen conditions using the RNA/DNA ratio and hsp70 gene expression. We exposed sand dollars to different temperature and oxygen conditions. Three experimental temperatures were similar to the ones that organisms experience during one annual cycle and two were considered extreme. Reduced oxygen conditions were considered when levels dropped below 4 mg L–1. To estimate variations in the stress-induced RNA/DNA ratio, we determined the value for males and females during a daily cycle. We also analyzed the hsp70 expression. Under stress conditions, a significant decrease was observed in the RNA/DNA ratios. The lowest values were detected after 6 h under normoxic conditions and high temperatures seemed to induce a major effect on the RNA/DNA ratios during the first hour of stress. Analysis of the hsp70 expression showed significant differences. According to our results, thermal and reduced oxygen stress induces a reduction in the general metabolism of the organisms. These metabolic changes were observed by the decrease in the RNA/DNA ratios and expression levels of hsp70 (at high temperatures). We conclude that RNA/DNA ratios are a useful ecophysiological tool to evaluate the effect of particular stressors on the physiology of D. excentricus, and seem to be more sensitive to oxygen levels than to thermal stress, in contrast to the hsp70 expression, which was more sensitive to extreme temperatures. En el Pacífico mexicano, Dendraster excentricus es un equinodermo común en estuarios y está sujeto a variaciones ambientales por el flujo de marea. Poco se conoce de su respuesta ecofisiológica cuando es expuesta a cambios de temperatura y oxígeno. Este estudio evalúa su respuesta al estrés térmico en condiciones normales y de oxígeno reducido, utilizando como indicadores el índice de ARN/ADN y la expresión del gen hsp70. Se expusieron las galletas de mar a diferentes temperaturas y niveles de oxígeno. Tres de las temperaturas experimentales fueron comunes a las que los organismos experimentan durante un ciclo anual y dos de ellas se consideran extremas. Se consideraron condiciones de oxígeno reducido en niveles por debajo de 4 mg L–1. Para estimar las variaciones inducidas por estrés en el índice de ARN/ADN, determinamos su valor en machos y hembras durante un ciclo diario. Además, analizamos la expresión del gen hsp70. En condiciones de estrés, se observó un decremento significativo en los índices de ARN/ADN. Los valores más bajos se detectaron después de 6 h en condiciones normales de oxígeno y las temperaturas altas parecieron inducir un mayor efecto en los índices durante la primera hora de estrés. El análisis de la expresión de hsp70 mostró diferencias significativas. Según nuestros resultados, el estrés térmico y por oxígeno induce una reducción general del metabolismo de los organismos. Estos cambios metabólicos se observaron en el decremento de los índices de ARN/ADN y en los niveles de la expresión de hsp70 (a altas temperaturas). Se concluye que los indices de ARN/ADN son una herramienta útil para entender la respuesta ecofisiológica en D. excentricus y parecen más sensibles a los niveles de oxígeno que al estrés térmico, en contraste con la expresión de hsp70 que resultó más sensible a las temperaturas extremas.Acceso al recurso -
8852
Synthesis and characterization of starch-g-PE copolymer using ethylene carbonate
Published 2023Fuente: Universidad del PapaloapanTipo de material: ArtículoDescripción: The banana starch reaction with polyethylene using ethylene carbonate was carried out by varying the starch/ethylene carbonate mass ratio (50–1000%). The starch-g-PE mass yield reached 89% mass conversion and a grafting yield of 0.52 when a starch/EC = 0.5 ratio was used, while the mass yield decreased until reaching a value of 26% when the starch/EC mass ratio increased. The final product was characterized by different instrumentals techniques to demonstrate copolymerization. The vibration signal of the carbonyl group (C=O) increased as that the starch/EC mass ratio decreased, indicating that the starch polymer chains are chemically interacting with the PE. The chemical bond signal between starch with carbonate group was assigned at δ 4.8 ppm. This modified starch is a material with less thermal stability than banana starch and polyethylene, and its degradation temperature decreases by 20 °C and 50 °C, respectively. The micrographs shown that the starch granules randomly agglomerate due to the presence of PE. Modified starch has a lower crystallinity than native starch. The viscosity of the starch-g-PE granules reached a value of 0.1 Pa s at temperature of 33 °C, while native starch reached a value of 5.0 Pa s at this same temperature. This product obtained is a moisture-resistant material due to the presence of PE chains and that could be used as a compatibilizer for post-consumer polymers such as polyalkanes.Acceso al recurso -
8853
The effect of ethylene glycol on starch-g-PCL graft copolymer synthesis
Published 2016Fuente: Universidad del PapaloapanTipo de material: ArtículoDescripción: The synthesis of the graft copolymer starch-g-PCL was carried out in a single phase, using molybdenum oxide as a catalyst, at a temperature of 150°C over a period of 24 h. Infrared spectroscopy and nuclear magnetic resonance analyses indicated that the graft copolymer was successfully synthesized, obtaining an 84% conversion yield. The introduction of ethylene glycol to the reaction influences the copolymer synthesis, affecting conversion yields and the physicochemical properties of the resultant copolymer. X-ray diffraction analysis indicates that the copolymer crystallinity decreases as ethylene glycol concentration increases. An investigation of the thermal properties of the graft copolymer suggested that the decomposition temperature of the copolymer, compared to that of the homopolymer, decreases with exposure to ethylene glycol. Scanning electron microscopy revealed the formation of clusters between the starch granules and the grafted copolymer due to the interaction of the hydroxyl groups of the starch and PCL.Acceso al recurso -
8854
Effect of Different Cooking Methods on The Nutritional Composition f Tilapia (Oreochromis Sp.)
Published 2020Fuente: Universidad del PapaloapanTipo de material: ArtículoDescripción: Tilapia (Oreochromis sp.) is a fish that is gaining ground in cultivation and sales because of its nutritional properties: high protein content, vitamins, and minerals with few unhealthy saturated fats as in red meats. This work aimed to evaluate the effect of cooking on the chemical composition, Aw, and pH, in addition to the electrophoretic, and fatty acid profile of the Tilapia using an electric oven, microwave and steaming as cooking methods. The results showed that the nutritional components of Tilapia changed significantly (p<0.05) at two temperatures and at two potencies used. Microwave and steaming preserved better the proteins in the Tilapia after its cooking. Electrophoresis results showed a decrease in intensity and number of bands depending on the type of treatment to which the meat was subjected. On the other hand, the electric oven method at 2 temperatures resulted with the highest increase in essential fatty acids (45% and 36%), with a slight decrease in the ω-6 family, because of a probable hydrolysis or oxidation of the same. The steam cooking showed a slight increase in essential fatty acids, but microwave oven preserved better the proteins, indicating that this could be a good method for cooking Tilapia.Acceso al recurso -
8855
Multiresponse optimization of the extrusion process for ready-to-eat snacks from pineapple byproducts and maize flour
Published 2023Fuente: Universidad del PapaloapanTipo de material: ArtículoDescripción: This research aimed to optimize the processing conditions to obtain ready-to-eat extruded snacks with a high fiber content from mixtures of pineapple byproduct powder (PBP) and nixtamalized maize flour (PBP-NMF) or maize flour (PBP-MF). The effects of barrel temperature, feed moisture content, and PBP were evaluated. The increase in barrel temperature has a negative effect on the bulk density, the water absorption index, and the texture in both mixtures (PBP-MF and PBP-NMF) and increases the expansion index and the water solubility index in the mixture with MF. The increase in the feed moisture content increased the bulk density and water absorption index in both mixtures and the texture in the mixtures with MF. The increasing PBP decreases the expansion index and increases the water solubility index in both mixtures. The increase in PBP in the mixtures with MF decreases the water absorption index, texture, and bulk density. From the optimization, four products were obtained, two for the NMF mixture and two for the MF mixtures. The optimal formulations can be considered a good source of total fiber (12.46−12.78 g/100 g) and protein (8.27−8.85 g/100 g) with good acceptance by consumers.Acceso al recurso -
8856
Effect of ultrasonic treatment on the morphological, physicochemical, functional, and rheological properties of starches with different granule size
Published 2016Fuente: Universidad del PapaloapanTipo de material: ArtículoDescripción: Sonication (25 kHz) was applied to plantain (large granule size) and taro (small granule size) starches for two treatment durations (20 and 50 min) using a flow-cell at controlled temperature of 4 ± 0.1°C. The granule size distribution of starches was only slightly affected by the ultrasound treatment. Ultrasound affected the granule surface morphology, as reflected by the profound cavities and fractures. Starch with larger granule size was more affected by ultrasound treatment, as reflected by the higher variation in the peak viscosity, swelling power, and solubility. Peak viscosity increased with ultrasound, whereas swelling power and solubility decreased after treatment. Additionally, ultrasound treatment of high granule size starch resulted in a more pronounced decrease in the storage modulus (G′) compared with its native counterpart.Acceso al recurso -
8857
Дослідження механізмів противиразкової активності кріоекстракту плаценти при серотоніновому ульцерогенезі...
Published 2022Fuente: ZenodoTipo de material: Recurso digitalAcceso al recurso -
8858
Modification of banana starch (Musa paradisiaca L.) with polyethylene terephthalate: Virgin and bottle waste
Published 2021Fuente: Universidad del PapaloapanTipo de material: ArtículoDescripción: Chemical modification of banana starch (Musa paradisiaca L.) with the degradation products of virgin and bottle waste of polyethylene terephthalate was carried out in situ. The modified starch was characterized by FTIR and NMR, which allowed proposing three chemical structures. SEM micrographs showed that the morphology of the modified starch granule is directly related with mass ratio of Starch/PET and type of PET used in the reaction. The crystallinity of the modified starch decreased up to 92.6% and 62.5% using bottle waste and virgin PET, respectively, according to XRD diffractograms. TGA analysis showed that the starch degradation temperature decreased by 12 °C. Modified starch films were elaborate and its electrical conductivity was found to be 2.9 times compared to that of native starch. The starch/PET film presented the highest value in the mechanical property of elongation at break compared to the starch-only film. The modified starch film was degraded above 80% by aqueous hydrolysis.Acceso al recurso -
8859
Effect of Crushed Glass Cullet Sizes on Physical and Mechanical Properties of Red Clay Bricks
Published 2016Fuente: Universidad del PapaloapanTipo de material: ArtículoDescripción: This study reports the effect of clear waste glass from bottles added on 20 to 30 wt.% and variable particle size (<500, <300, and<212 𝜇m), into clay mixtures for the handmade brick manufacturing process. The bricks were manufactured with mixtures of clay,crushed glass, and water in different proportions, homogenized, casted in wooden molds, air-dried at room temperature for 72 h,and sintered at 1000∘C for 12 h. Total shrinkage, water absorption, compressive strength, microstructure, and phase composition arediscussed with respect to glass content and its particle size. The results indicate that increasing the content of glass and decreasing itsparticle size enhanced significantly the brick properties of water absorption and compressive strength by up to 18.5% and 6.8 MPa,for bricks with 30 wt% and particle size lower than 212 𝜇m. It is proposed that decreasing the glass particle size its surface areaincreases allowing easier melting of glass by lower energy consumption, reducing porosity and enhancing brick propertiesAcceso al recurso -
8860
Clusters of starch-g-PCL and their effect on the physicochemical properties of films
Published 2017Fuente: Universidad del PapaloapanTipo de material: ArtículoDescripción: Starch-g-PCL films were prepared using the casting method and were characterized by different instrumental techniques and physicochemical properties. Nuclear magnetic resonance and Fourier transform infrared spectroscopy led to the proposal of a chemical structure for the films. The scanning electron microscopy (SEM) images of the films showed the formation of clusters of the graft copolymer starch-g-PCL. The effects of these clusters on the crystallinity (X-ray powder diffraction) revealed that the crystalline zones of the films increased by 46% and the elongation percentage increased by up to 50%. Also, the chemical degradation (aqueous hydrolysis) and the soil degradation of these films were 1.9 and 2.6 times faster than the films of starch alone. However, the thermal degradation temperature of the films decreased by more than 15°C, the moisture content decreased to 6.5%, and the water vapor permeation values increased in the films that contained starch-g-PCL. These results were accentuated with the increase in the amount of starch-g-PCL clusters.Acceso al recurso