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8901
Spray-drying of Escontria chiotilla fruit juice: effect of the process variables on yield and physicochemical properties
Pubblicazione 2024Fuente: Universidad del PapaloapanTipo de material: ArtículoDescripción: Escontria chiotilla (jiotilla) fruit pulp has a high content of sugars, vitamins, antioxidants, and betalains. However, jiotilla fruits exhibit high susceptibility to microbial attack and physicochemical degradation during storage. Spray-drying of jiotilla fruit juice rich in betalains was carried out using maltodextrin as a carrier material. The effects of inlet (140 and 160 °C) and outlet (80 and 90 °C) temperatures and maltodextrin levels (1 and 2 g·g juice solids⁻¹) on process yield and physicochemical properties of jiotilla powders were studied. Maltodextrin concentration significantly affected (p < 0.05) all evaluated responses, except a_w and °Hue values, whereas drying temperatures did not significantly affect any response. An increase in process yield and luminosity, along with a decrease in chroma values and betalain content, was observed as maltodextrin concentration increased. Physicochemically stable powders (a_w < 0.25), with a color tendency toward red (°Hue: 11–13°), intermediate cohesiveness, fair-to-good flowability, high solubility (92.16%), low hygroscopicity (16.28 g H₂O·100 g db⁻¹), and high contents of betacyanins (82.4–127.1 mg BC·100 g db⁻¹) and betaxanthins (174.7–275.3 mg BX·100 g db⁻¹) were obtained. Jiotilla powder could be applied in the development of food products, even outside the jiotilla fruit production season.Acceso al recurso -
8902
In search of cytotoxic selectivity on cancer cells with biogenically synthesized Ag/AgCl nanoparticles
Pubblicazione 2022Fuente: Universidad del PapaloapanTipo de material: ArtículoDescripción: Green synthesis may be a useful approach to achieve selective cytotoxicity of silver nanoparticles on cancer cells and healthy cells. In this study, the concomitant biosynthesis of silver (Ag)/silver chloride (AgCl) nanoparticles from pineapple peel extracts and their behavior on the breast cancer cell line MCF-7 is shown. Bioreactions were monitored at different temperatures. Fourier-transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV–vis), thermogravimetric analysis (TGA), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) techniques were used to characterize nanoparticle development. The breast cancer cell line MCF-7 was used as a test model to study the cytotoxic behavior of Ag/AgCl nanoparticles and, as a counterpart, the nanoparticles were also tested on mononuclear cells. Ag/AgCl nanoparticles with spherical and triangular morphology were obtained. The size of the nanoparticles (10–70 nm) and the size distribution depended on the reaction temperature. A dose close to 20 µg/mL of Ag/AgCl nanoparticles considerably decreased the cell viability of the MCF-7 line. The best cytotoxicity effects on cancer cells were obtained with nanoparticles at 60 and 80 °C where cell viability was reduced up to 80% at a concentration of 50 µg/mL. A significant preference was observed in the cytotoxic effect of Ag/AgCl nanoparticles against cancer cells in comparison to monocytes.Acceso al recurso -
8903
Dual modification of chayotextle starch: effect on physicochemical, functional, and structural properties
Pubblicazione 2023Fuente: Universidad del PapaloapanTipo de material: ArtículoDescripción: Chemically modified starches are widely used as food additives to improve the appearance and physicochemical and biological properties of foods. The aim of this work is to chemically modify chayotextle (Sechium edule) starch by hydroxypropylation-crosslinking, and evaluate the effects of degree of substitution (DS), swelling power (SP), solubility index (SI), pasting, thermal properties, and morphological and molecular characteristics. Polar-Tex (modified maize starch) is used as control. The modified chayotextle starches (CHSs) exhibit a white color and DS values between 0.34% and 1.19% hydroxypropyl, dependening on propylene oxide concentration-response. In addition, the SP and pasting properties are higher in modified CHS than in native CHS and Polar-Tex. The SI and temperature of gelatinization of modified starches decrease compared to native sample. The morphology of native and modified CHS granules is spherical and oval. Fourier transform infrared and nuclear magnetic resonance studies confirm the structural modifications of CHS by hydroxypropylation-crosslinking. Dual-modified CHS can be potentially used as an additive in the food industry.Acceso al recurso -
8904
Efecto del estrés en la respuesta ecofisiológica de la galleta de mar Dendraster excentricus en el noroeste de México
Pubblicato 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 -
8905
Effects of formulation and process conditions on chemical composition, color parameters, and acceptability of extruded insect-rich snack
Pubblicazione 2021Fuente: Universidad del PapaloapanTipo de material: ArtículoDescripción: A ready-to-eat, protein-rich snack was developed using a blend of nixtamalized maize (Zea mays L.) flour and grasshopper (Sphenarium purpurascens Ch.) meal, and an evaluation of the effects of the formulation and extrusion processing on the chemical composition, color parameters, and acceptability of the extrudates was conducted. The increase in extrusion temperature (120–180ºC) decreased the moisture (8.14–5.91 g/100 g) and lipid content (2.20–1.95 g/100 g) and increased aroma (3.82–4.24), texture (1.61–4.82), flavor (2.67–4.52), and overall acceptability (2.88–4.67). The increase in the grasshopper meal proportion (0–40 g/100 g) decreased the carbohydrate content (89.45–65.39 g/100 g), and whiteness index (68.51–47.14) and increased the protein (5.33–22.51 g/100 g) and ash contents (1.67–7.88 g/100 g), color difference (30.98–52.30), and browning index (24.28–39.77). The acceptability of the snack was oriented toward extrudates that had a color with a high L* (Corr = 0.74), with yellow tones b* (Corr = 0.73), and a whiteness index (Corr = 0.72). Therefore, the best products were those obtained at 167.8°C, proportion of grasshopper meal = 8.11 g/100 g, and a feed moisture content of 18.81 and 21.19 g/100 g, respectively, with a protein content of 13.27 and 13.66 g/100 g.Acceso al recurso -
8906
Resistant starch from plantain (Macho Musa paradisiaca L.) and banana (Roatan Musa sapientum L.) varieties crosslinked with epichlorohydrin
Pubblicazione 2024Fuente: Universidad del PapaloapanTipo de material: ArtículoDescripción: Resistant starch from plantain (Macho Musa paradisiaca L.) and banana (Roatan Musa sapientum L.) varieties was chemically modified by crosslinking using epichlorohydrin (EPI). These modified starches were subjected to in vitro digestibility studies using the Englyst method to determine the content of rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS). The thermal stability of these crosslinked starches was evaluated by gelatinization and retrogradation analyses, and their enthalpies were determined using differential scanning calorimetry (DSC). Additionally, their functional properties were evaluated. Chemical modification with EPI significantly increased the RS content in both starch varieties compared to that in native starch. The enthalpy and gelatinization temperature decreased in the EPI-modified starches of both varieties, indicating lower thermal stability during the gelatinization process compared to that of native starch. In general, both varieties of crosslinked plantain starch had lower viscosity (0.43 Pa*s) than did native starch (0.58 Pa*s). The results indicates that this starch crosslinked with EPI constitutes an alternative for use in food for people with health problems such as high cholesterol levels or postprandial insulin concentrations.Acceso al recurso -
8907
Tendencias temporales (19891999) en las poblaciones de Haliotis fulgens y H. corrugata (Gastropoda:Haliotidae) de Isla de Cedros, Baja California, México
Pubblicato in Ciencias Marinas (2004)Fuente: Redalyc · Ciencias MarinasTipo de material: Artículo científicoDescripción: This work analyzes the temporal trends (1989–1999) of populations of Haliotis fulgens and H. corrugata from Cedros Island, Baja California (Mexico). The mean total density of H. fulgens in the northern (Punta Norte) and southwestern (San Agustín) points of Cedros Island showed a significant decreasing trend, while H. corrugata showed that trend only at San Agustín. Only the mean density of the legal-sized stock of H. fulgens presented a significant decreasing trend at the island. The density extracted due to fishing of H. corrugata at Punta Norte showed a significant increasing trend, but the abundance of its legal-sized stock did not show a significant decreasing trend. Authorized extraction levels for both species at Cedros Island have been lower than the maximum allowed in Mexico (30% of the legal-sized stock of each species for each fishing zone). Recent percentages of recruitment of both species are low and show no significant temporal trends. Apparently, recruitment of both species at Punta Norte decreases when the water temperature increases. A significant negative relationship was found between the physiological condition of both species and increased water temperature at Punta Norte, but such a relationship was absent at San Agustín, suggesting that the effect of warm events may differ among neighboring locations or that the populations differ in physiological tolerance. The magnitude and frequency of fluctuations in the physiological condition of both species should be taken into account when fishing quotas are assigned, since they will surely influence the magnitude and quality of spawning and natural mortality. Este trabajo, junto con publicaciones recientes sobre la abundancia del abulón en Isla Natividad y el Archipiélago San Benito, forma un cuadro que refleja el estado y la dinámica temporal de este recurso en la costa oeste de Baja California. Se analizaron las tendencias temporales (1989–1999) de las poblaciones de Haliotis fulgens y H. corrugata de Isla de Cedros. La densidad total media de H. fulgens en el extremo norte (Punta Norte) y suroeste (San Agustín) de Isla de Cedros muestra tendencias decrecientes significativas, mientras que H. corrugata muestra esa tendencia sólo en San Agustín. Únicamente la densidad media del stock de talla legal de H. fulgens muestra tendencias significativas al decremento en la isla. La densidad extraída por pesca de H. corrugata en Punta Norte muestra una tendencia significativa al incremento, sin que la abundancia de su stock legal tenga una tendencia decreciente significativa. Los niveles de extracción autorizados para ambas especies en Isla de Cedros han sido menores al máximo permisible en México (30% del stock legal de cada especie en cada zona de captura). Los porcentajes de reclutamiento recientes en ambas especies son bajos y no mostraron tendencias temporales significativas. Aparentemente, el reclutamiento de ambas especies en Punta Norte decrece al incrementarse la temperatura del agua. En Punta Norte se encontró una relación negativa significativa entre la condición fisiológica de ambas especies y el incremento en la temperatura superficial del agua. Sin embargo, dicha relación estuvo ausente en San Agustín, sugiriendo que los efectos de los eventos cálidos pueden diferir entre localidades aledañas, o que sus poblacionales difieren en tolerancia fisiológica. La frecuencia y magnitud de las fluctuaciones en la condición fisiológica de ambas especies deberían ser tomadas en cuenta para la asignación de cuotas de captura, pues estas repercuten seguramente sobre la magnitud y calidad de los desoves y la mortalidad natural.Acceso al recurso -
8908
Effect of cross-linking on the physicochemical, functional and digestibility properties of starch from Macho (Musa paradisiaca L.) and Roatan (Musa sapientum L.) banana varieties
Pubblicazione 2015Fuente: Universidad del PapaloapanTipo de material: ArtículoDescripción: Starches from the Macho (Musa paradisiaca L.) and Roatan (Musa sapientum L.) banana varieties were chemically modified by sodium trimetaphosphate (STMP) cross-linking. Cross-linking affected the pasting properties of the modified starch, with more pronounced changes observed in the Macho variety than in the Roatan starch. In turn, this result indicated that the former starch source is more susceptible to STMP cross-linking. The swelling and solubility profiles exhibited an important decrease with cross-linking, which was caused by increased ordering of the internal granule structure induced by cross-linking modifications. The gelatinization temperature and enthalpy increased due to cross-linking, indicating an improvement in the starch granule stability. Englyst's in vitro digestibility studies of the modified starch were performed to estimate the content of rapidly digestible (RDS), slowly digestible (SDS) and resistant (RS) starch fractions. It was shown that STMP cross-linking increased the RS content of the two banana varieties. However, the SDS content increased only for the Macho variety. In general, the viscosity was lower for the modified starches than for their native counterparts. The results of the current work indicate that the chemical modification process via STMP cross-linking offers an interesting alternative for obtaining RS from banana starches.Acceso al recurso -
8909
Efectos de la irradiación y el nitrato sobre la fotosíntesis en el pasto marino Cymodocea nodosa
Pubblicato in Ciencias Marinas (2023)Fuente: Ciencias MarinasTipo de material: Artículo científicoDescripción: The effects of temperature, irradiance, and other environmental variables on photosynthesis in seagrasses are well understood. However, little information is available regarding the effects of the nitrate concentration in seawater on the photosynthetic characteristics of marine vegetation. Thus, the aim of this study was to determine the effect of the nitrate concentration in seawater on the effective quantum yield of the seagrass Cymodocea nodosa. Cymodocea nodosa shoots were incubated under different irradiance levels and with different nitrate concentrations. In contrast, a decrease in transmittance and an exponential increase in the absorptance of the shoots were observed as a function of increasing nitrate levels. Furthermore, the effective quantum yield of photosystem II (ΦPSII) in C. nodosa shoots increased exponentially as the nitrate concentration in the media increased. The ΦPSII values in the shoots decreased as irradiance increased and reached minimum values at solar noon or 2 h afterward. However, the decrease of ΦPSII values was 4-fold greater in shoots incubated under full solar radiation (100% natural incident irradiance, Eo) compared to those of shoots incubated with 20% Eo. The ΦPSII values decreased to almost zero in shoots pre-incubated with no nitrate (0 μM NO3–), whereas ΦPSII values in shoots pre incubated with 25 and 100 μM NO3– decreased by approximately 25% of their initial values. Collectively, these results indicate that nitrogen levels in seawater regulate the effective quantum yield values of C. nodosa, which suggests that the photosynthetic characteristics of this seagrass might be regulated by fluctuating nitrate levels in the water column such as those that are observed in upwelling regions. Los efectos de la temperatura, la irradiancia y otras variables ambientales sobre la fotosíntesis en los pastos marinos son bien conocidos. Sin embargo, existe poca información sobre los efectos del nitrato en el agua marina sobre las características fotosintéticas de los macrófitos marinos. En este estudio, se planteó determinar el efecto de la concentración de nitrato en el agua marina sobre el rendimiento cuántico efectivo del pasto marino Cymodocea nodosa. Los haces de C. nodosa se incubaron con diferentes concentraciones de nitrato y bajo diferentes niveles de irradiancia. En contraste, hubo una disminución de la transmitancia y un aumento exponencial de la absortancia de los haces en función del aumento de los niveles de nitrato. Además, el rendimiento cuántico efectivo del fotosistema II (ΦFSII) en los haces de C. nodosa aumentó exponencialmente al aumentar la concentración de nitrato en el medio. Los valores de ΦFSII en los haces disminuyeron a medida que aumentaba la irradiancia y alcanzaron valores mínimos al mediodía solar o 2 h después. Esta disminución en los valores de ΦFSII, sin embargo, fue 4 veces mayor en los haces incubados bajo radiación solar completa (100% de Eo) en comparación con los incubados con 20% de Eo. Los valores de ΦFSII disminuyeron a casi cero en los haces pre-incubados con 0 μM de NO3–, mientras que los valores de ΦFSII en los haces pre-incubados con 25 y 100 μM de NO3– disminuyeron aproximadamente un 25% de sus valores iniciales. Estos resultados indican que los niveles de nitrógeno en el agua marina regulan los valores del rendimiento cuántico efectivo de C. nodosa, lo que sugiere que las características fotosintéticas de este pasto marino podrían estar reguladas por los niveles fluctuantes de nitrato en la columna de agua como aquellos observados en las regiones de surgencia.Acceso al recurso -
8910
SEC-ZEFFO COSMOLOGY: UNIFIED RESOLUTION OF DARK MATTER, DARK ENERGY, H₀ TENSION, AND BLACK HOLE INFORMATION PARADOX VIA GRAVITATIONAL POLARISATION*
Pubblicazione 2026Fuente: ZenodoTipo de material: Recurso digitalAcceso al recurso -
8911
Effect of oxidation and crosslinking on functional, rheological and thermal properties of oat and apple starches
Pubblicazione 2024Fuente: Universidad del PapaloapanTipo de material: ArtículoDescripción: Oat (Oa) and apple (Ap) starches were isolated and chemically modified by oxidation with 10% NaOCl to obtain oxidized starches (OOa and OAp), followed by cross-linking with a mixture of 5.6 g of sodium tripolyphosphate and 11 g of sodium trimetaphosphate to obtain doubly modified starches (OCOa and OCAp). In the native and modified starches, the functional properties (swelling power and solubility, and freeze-thaw stability) and thermal and rheological properties (steady-state flow curves and paste formation profile) were evaluated. The swelling power of native and double modified starches varied from 57 to 86 g/g and the solubility from 0.8 to 6.0 g/100 g, these variables increased as the study temperature increased; the increment in these properties was greater in Oa compared to Ap. Oxidation followed by crosslinking increased the freeze-thaw stability in Oa and Ap starches at 30, 60, 75, and 90 °C. It also increased the Tg of OCAp and OCOa ≈ 9% compared to the native samples, respectively; while an inverse pattern was observed in apparent viscosity were this value decreased ≈ 0.8 Pa × s for Oa and ≈ 0.5 Pa × s for Ap compared to the double modified samples. All samples presented a thinning cut-type behavior (pseudoplastic), indicating structural differences. Cross-linking in oxidized starches produced a reinforcing matrix that was determined in the paste formation profile. Dual modification (oxidation-cross-linking) could be an alternative for using starches from underused botanical sources, such as apples and oats, with different functional properties and feasible applications in food systems.Acceso al recurso -
8912
Growth, yield, fiber content and lodging resistance in eight varieties of Cenchrus purpureus (Schumach.) Morrone intended as energy crop
Pubblicazione 2016Fuente: Universidad del PapaloapanTipo de material: ArtículoDescripción: Growth, biomass yield, fiber content and lodging resistance were studied, during a six month growth period, for eight varieties of Cenchrus purpureus, intended as energy crop, in Veracruz, Mexico. Then, only yield at day 182 was assessed for two additional years. The varieties were: CT115 (CT), African Cane (AC), Taiwan (TAI), King Grass (KG), Vruckwona (VRU), Roxo (RX), OM22 (OM) and Cameroon (CAM). Local weather is warm and sub-humid, historical data for monthly average temperature and annual rainfall were 25.8 °C and 1142 mm, respectively. Height, diameter and light interception were measured monthly from day 65–185. At day 185, biomass yield and tiller density were measured. Number of lying tillers was counted to estimate lodging resistance. Cellulose and hemicellulose content were estimated in leaf and stem. No differences were found for dry matter yield or stem yield at day 185 in the first year. Regarding the next two years, TAI yielded above CT, OM or ROX. Average dry matter yield was higher in the second year than in the establishment cycle (38.6 vs 21.1 Mg ha−1), but decreased in the third year (32.2 Mg ha−1). In both stem and whole plant, AC and KG showed higher hemicellulose content than RX, OM or CT; while AC and VRU had higher cellulose than RX in stem, or than CT in the whole plant. Furthermore, varieties AC, KG, VRU and TAI were resistant to lodging and had a higher fiber content, so they are recommended as energetic crops.Acceso al recurso -
8913
Hidrografía en la Boca Norte de la Bahía de La Paz, Baja California Sur, México
Pubblicato in Ciencias Marinas (2007)Fuente: Redalyc · Ciencias MarinasTipo de material: Artículo científicoDescripción: To describe the hydrographical variability at the North Mouth of La Paz Bay, its main point of communication with the Gulf of California, CTD data were analyzed from four sampling surveys conducted during an annual cycle (May, July and October 2001, and February 2002). The results showed an absence of the mixed layer and intense temperature and salinity stratification in spring and summer. In autumn a 30-m mixed layer was registered, with a temperature of 28.5ºC, while in winter an unusual 100-m mixed layer was detected, with a temperature of 17.9ºC. Particular noteworthy is the similarity of the structure between the surface and subsurface layers of the bay and gulf. The most significant difference was the presence of Pacific Intermediate Water (PIW) in the gulf, which does not intrude into the bay due to the barrier created by the sill at the mouth. The T-S diagrams revealed the presence of Gulf of California Water (GCW), Subtropical Subsurface Water (SSW) and PIW in May. In July, however, four water masses were identified: GCW, Equatorial Surface Water (ESW), SSW and PIW. In October, a significant amount of ESW and a considerable decrease in GCW were detected, but in February only GCW and SSW were found. This study shows important hydrographic seasonal variability in the area of the North Mouth, with marked differences between the bay and the gulf, contributing to the understanding of the regional oceanography. Con el objetivo de describir la variabilidad hidrográfica en la principal comunicación de la Bahía de La Paz con el Golfo de California, llamada Boca Norte, se analizaron datos de CTD de cuatro campañas de muestreo realizadas durante un ciclo anual (mayo, julio y octubre de 2001, así como febrero de 2002). Los resultados muestran en la primavera y el verano una ausencia de una capa de mezcla, con una intensa estratificación de temperatura y salinidad, mientras que en el otoño se registró una capa de mezcla de 30 m con una temperatura de 28.5ºC, y en el invierno se detecta una inusual capa de mezcla de más de 100 m, con una temperatura de 17.9ºC. Es de destacar que las capas superficial y subsuperficial de la bahía y el golfo, presentan una estructura similar, siendo la diferencia más significativa la presencia en el golfo de Agua Intermedia del Pacífico (AIP), la cual no penetra a la bahía debido a la barrera que representa el Umbral de la Boca Norte. En los diagramas T-S se observa en mayo la presencia de Agua del Golfo de California (AGC), Agua Subsuperficial Subtropical (ASS) y AIP, mientras que en julio se indentificaron cuatro masas de agua, AGC, Agua Superficial Ecuatorial (ASE), ASS y AIP. En octubre se detectó una gran cantidad de ASE y una fuerte disminución del AGC; sin embargo, en febrero se encontró únicamente AGC y ASS. Este estudio muestra una importante variabilidad estacional hidrográfica en la zona de la Boca Norte, con marcadas diferencias entre la bahía y el golfo, lo que proporciona una contribución a la oceanografía regional.Acceso al recurso -
8914
Preengorda del Ostión Americano (Crassostrea virginica) en lagunas costeras tropicales en Yucatán, México: modelación de regresión no lineal y relaciones con variables ambientales...
Pubblicato in Ciencias Marinas (2024)Fuente: Ciencias MarinasTipo de material: Artículo científicoDescripción: Nonlinear regression modeling was used to study the nursery production of the oyster Crassostrea virginica in the Celestún (CL) and Rio Lagartos (RL) lagoons in Yucatán, Mexico. Relationships between production parameters and environmental variables were also established. Spat (2.40 ± 0.20 mm) was obtained from a hatchery and reared in Nestier-type trays using an off-bottom system. Oyster cultivation took place from May 2021 to September 2021 and ended after 122–126 days when oysters reached 30.00 mm. There were no significant differences in final height (CL: 30.80 ± 0.42 mm; RL: 31.80 ± 0.65 mm; P = 0.18) and growth rate (CL: 0.23 ± 0.02 mm·d–1; RL: 0.23 ± 0.01 mm·d–1; P = 0.98). Final survival was 71.45% in CL and 99.40% in RL. Nonlinear regression curves were statistically satisfactory for analyzing growth and survival. Except for dissolved oxygen, mean salinity (CL: 15.23 ppt; RL: 35.02 ppt), temperature (CL: 29.64 °C; RL: 31.02 °C), dissolved oxygen (CL: 4.50 mg·L–1; RL: 5.04 mg·L–1), pH (CL: 8.10; RL: 8.34), chlorophyll a (Chl a) (CL: 3.23 mg·m–3; RL: 6.85 mg·m–3), and total dissolved solids (CL: 16,101 mg·L–1; RL: 34,838 mg·L–1) were significantly higher in RL (P < 0.05). Except for Chl a, the environmental variables were more stable in RL than in CL (P < 0.05). In RL, the growth rate was positively related to salinity and pH. In CL, the growth rate slowed when salinity decreased, and the mortality rate diminished when salinity, dissolved oxygen, and total dissolved solids increased and pH decreased. Salinity was mainly responsible for the observed differences in production between lagoons. Even when temperature and salinity were high in RL, acceptable growth rate and survival were observed, possibly due to stable rearing conditions. Se usaron modelos de regresión no lineal para analizar la producción en preengorda de Crassostrea virginica en 2 lagunas costeras de Yucatán, México: Celestún (CL) y Río Lagartos (RL). Adicionalmente, se establecieron relaciones entre la producción y las variables ambientales. Las semillas (2.40 ± 0.2 mm) se cultivaron en suspensión de mayo a septiembre 2021 en canastas Nestier durante 122-126 días, hasta que los ostiones alcanzaron 30.00 mm. No hubo diferencias significativas en la altura final (CL: 30.80 ± 0.42 mm; RL: 31.80 ± 0.65 mm; P = 0.18) ni en la tasa de crecimiento (CL: 0.23 ± 0.02 mm·d–1; RL: 0.23 ± 0.01 mm·d–1; P = 0.98) entre sitios. La supervivencia fue 71.40% en CL y 99.40% en RL. Las curvas de regresión no lineal resultaron estadísticamente satisfactorias para analizar el crecimiento y la supervivencia. La salinidad (CL: 15.23 ppt; RL: 35.02 ppt), la temperatura (CL: 29.64 °C; RL: 31.02 °C), el oxígeno disuelto (CL: 4.50 mg·L–1; RL: 5.04 mg·L–1), el pH (CL: 8.10; RL: 8.34), la clorofila a (Cl a) (CL: 3.23 mg·m–3; RL: 6.85 mg·m–3) y los sólidos disueltos totales (CL: 16,101 mg·L–1; RL: 34,838 mg·L–1) fueron superiores en RL (P < 0.05). Exceptuando la Cl a, las variables fueron más estables en RL (P < 0.05). En RL, el crecimiento se relacionó positivamente con la salinidad y el pH. En CL, el crecimiento disminuyó al bajar la salinidad, y la mortalidad disminuyó cuando la salinidad, el oxígeno disuelto y el total de sólidos disueltos se incrementaron y el pH disminuyó. La salinidad fue determinante para la diferencia en producción entre las lagunas. En RL, el crecimiento y la supervivencia fueron aceptables aun con temperaturas y salinidades relativamente elevadas, posiblemente debido a las condiciones estables de cultivo.Acceso al recurso -
8915
Respuesta de los poliquetos bentónicos a la variabilidad ambiental y condiciones El Niño en Bahía Petacalco (Guerrero, México)
Pubblicato in Ciencias Marinas (2004)Fuente: Redalyc · Ciencias MarinasTipo de material: Artículo científicoDescripción: Fluctuations of temperature, salinity, and dissolved oxygen in the superficial (0–7 m) and lower (7–23 m) layers of the water column in Petacalco Bay (Guerrero, Mexico) and their effects on benthic polychaetes were analyzed on different dates between 1992 and 1994. Samplings undertaken during 1992 allowed the detection of the terminal phase of the 1992 El Niño event, followed by the discharge of warm freshwater from a power plant (2100 MW) over the surface of the bay. During the 1992 El Niño, the water was significantly warmer, more saline, and contained more oxygen than during 1993–1994. Stratification of the water column increased after the dissipation of El Niño conditions, and dissolved oxygen and salinity levels decreased noticeably. Polychaete abundances and the number of species were lowest during the El Niño period and increased afterwards. These changes occurred despite the operation of the power plant, since its discharges remained on the surface of the bay. Emersions of deep water through the Petacalco submarine canyon in spring may also have had a positive effect. Se analizaron las fluctuaciones en temperatura, salinidad y oxígeno disuelto en las capas superficial (0–7 m) e inferior (7–23 m) de la columna de agua de Bahía Petacalco (Guerrero, México), y sus efectos sobre los poliquetos bentónicos, en diferentes fechas de 1992–1994. Los muestreos de 1992 permitieron capturar la fase terminal del evento El Niño 1992, seguido de la descarga de agua dulce del sistema de enfriamiento de una central termoeléctrica (2100 MW) en la superficie de la bahía. Durante El Niño 1992 el agua de la bahía estuvo significativamente más caliente, salina y oxigenada que entre 1993–1994. Al retirarse las condiciones El Niño, se incrementó la estratificación en la columna de agua y los niveles de oxígeno disuelto y salinidad se redujeron notoriamente. Después de El Niño, los poliquetos se recuperaron de niveles mínimos de abundancia y número de especies, a pesar de las descargas de la termoeléctrica que se mantuvieron sobre la superficie de la columna de agua. Afloramientos de agua profunda a través del cañón submarino Petacalco durante la primavera pudieron haber tenido un efecto positivo.Acceso al recurso -
8916
Distribución espaciotemporal de la contaminación bacteriana del agua residual agrícola y doméstica descargada a un canal de drenaje (Sinaloa, México)
Pubblicato in Ciencias Marinas (2013)Fuente: SIBUMAR · Ciencias MarinasTipo de material: LibroDescripción: The agricultural drainage water from the Sinaloa valley (Mexico) is often reused in agriculture and aquaculture before reaching coastal water bodies. Discharged water must be of good quality to maintain the health of ecosystems and prevent damage to the organisms that compose them. This research determined the occurrence of coliforms in a drainage ditch known as La Michoacana (Sinaloa) that receives contaminated water from agricultural and urban sources. A section of 3.6 km was studied during 2013 and samples were obtained monthly from five equidistant sampling sites. Each water sample was analyzed for total coliform (TC) and fecal coliform (FC) content, pH, salinity, temperature, and dissolved oxygen percentage (%DO). The sampling sites with the highest bacterial contamination were associated with direct discharges of domestic wastewater and those with the lowest to the output drain. The performance of this agricultural ditch decreased the concentration of coliforms, with median and average values of 96% and 87% for TC, and 98% and 85% for FC, respectively. The most common bacteria were Escherichia coli (67.7%), Kluyvera cryocrescens (10.2%), and Enterobacter agglomerans (6.3%). Coliform concentration was positively correlated with temperature and negatively with %DO. The ditch improved the microbiological quality of the water, demonstrating remediation activities in the system. Proper management and maintenance of agricultural drainage ditches would favorably impact the health and biodiversity, as well as the intensive aquaculture and agricultural activities of the Sinaloa valley. El agua que conducen los canales de drenaje del valle agrícola sinaloense (México) es reutilizada con frecuencia en la agricultura y acuacultura antes de ser depositada en las aguas costeras. La calidad del agua descargada debe ser adecuada para mantener la salud de los ecosistemas y evitar daño a los organismos que los componen. Esta investigación determinó la presencia de coliformes en el canal de drenaje agrícola conocido como La Michoacana (Sinaloa), que recibe agua contaminada de fuentes agrícolas y urbanas. Se estudió una sección de 3.6 km del canal durante el año 2013 y se recolectaron mensualmente muestras de agua de cinco puntos de muestreo equidistantes. A cada muestra se le analizó el contenido de coliformes totales (CT) y coliformes fecales (CF), pH, salinidad, temperatura y porcentaje de saturación de oxígeno disuelto (%OD). Los puntos de muestreo con mayor contaminación bacteriana estuvieron asociados a las descargas directas de agua residual doméstica, y aquellos con menor contaminación estuvieron asociados a la salida del canal de drenaje. El funcionamiento del canal disminuyó la carga de coliformes, con medianas y valores promedio del 96% y 87% para CT, y 98% y 85% para CF, respectivamente. Las principales bacterias identificadas fueron Escherichia coli (67.7%), Kluyvera cryocrescens (10.2%) y Enterobacter agglomerans (6.3%). La concentración de coliformes presentó una correlación positiva con la temperatura y negativa con el %OD. El canal de drenaje La Michoacana mejora la calidad microbiológica del agua que conduce, lo cual demuestra funciones de remediación en el sistema. El mantenimiento y manejo adecuado de los canales de drenaje agrícola puede impactar favorablemente la salud y biodiversidad, así como las actividades acuícolas y agrícolas intensivas del valle sinaloense.Acceso al recurso -
8917
The Nexus Framework: Recursive Harmonic Genesis and the Digital Substrate of Reality
Pubblicazione 2026Fuente: ZenodoTipo de material: Recurso digitalAcceso al recurso -
8918
Efectos de la pesquería del pulpo sobre la población de la cacerolita de mar en la Reserva de la Biosfera Ría Lagartos, México
Pubblicato in Ciencias Marinas (2020)Fuente: Ciencias MarinasTipo de material: Artículo científicoDescripción: The American horseshoe crab, Limulus polyphemus, has been reported to be illegally caught for use as Octopus spp. bait in some localities of the Yucatán Peninsula, Mexico. To learn if the octopus fishery could be negatively influencing the limulus populations in the area, L. polyphemus individuals were sampled twice a year, before and after the annual octopus fishing season, over 4 consecutive years (2015–2018) in Río Lagartos and San Felipe, both in the Ría Lagartos Biosphere Reserve (RLBR), Yucatán. Quadrants were drawn perpendicular to the mangrove edge, physicochemical parameters in the water (depth, temperature, dissolved oxygen, pH, salinity, and electrical conductivity) were determined, and granulometry of marine sediments was measured (Folk technique). The number of live specimens, number of females, and average length were recorded. No significant differences were found for the physicochemical properties of water or the recorded sedimentology (P > 0.05). Samplings revealed a low number of organisms per site: 22 in Río Lagartos and 24 in San Felipe, both from data before the start of the 2017 octopus fishing season. In the samplings after the start of the 2018 octopus fishing season, only 2 organisms were observed in Río Lagartos and none in San Felipe. The results showed a significant decrease in the number of live L. polyphemus specimens after the beginning of the octopus fishing season and a decrease in the average length of organisms, suggesting a negative effect of mollusk fishing activities on the horseshoe crab populations. More studies are required that integrate other physicochemical, biological, and socioeconomic factors to elucidate the potential threat of this fishery on L. polyphemus populations in the RLBR. Se ha documentado que la cacerolita de mar Limulus polyphemus se captura de forma ilegal para uso como carnada de Octopus spp. en algunas localidades de la península de Yucatán, México. Para conocer si la pesquería de pulpo pudiese tener una influencia negativa en las poblaciones de este límulo, se muestrearon organismos de L. polyphemus 2 veces al año, antes y después del comienzo de la temporada anual de pulpo, durante 4 años consecutivos (2015–2018) en Río Lagartos y San Felipe, situados en la Reserva de la Biosfera Ría Lagartos (RBRL), Yucatán. Se trazaron cuadrantes perpendiculares a la vera del manglar y se midieron los parámetros fisicoquímicos del agua (profundidad, temperatura, oxígeno disuelto, pH, salinidad y conductividad eléctrica), así como la granulometría del sedimento marino (mediante el tamizado de Folk). Se registró el número de individuos vivos, el número de hembras y la longitud promedio. No se encontraron diferencias significativas en los parámetros fisicoquímicos del agua ni en la sedimentología registrada (P > 0.05). Los muestreos evidenciaron pocos organismos por sitio estudiado: 22 en Río Lagartos y 24 en San Felipe, ambos resultados antes de iniciada la temporada de pulpo de 2017. En los muestreos posteriores al inicio de la temporada de pulpo de 2018, solo se observaron 2 organismos en Río Lagartos y ninguno en San Felipe. Los resultados evidenciaron una disminución significativa en el número de ejemplares vivos de L. polyphemus después de iniciada la temporada de pulpo, así como también una disminución en la longitud promedio de los organismos, lo que sugiere un efecto negativo en las poblaciones de la cacerolita de mar derivado de las actividades propias de la pesca del molusco. Se requieren más estudios que integren otros factores fisicoquímicos, biológicos y socioeconómicos para dilucidar la potencial amenaza de esta pesquería sobre las poblaciones de este límulo en la RBRL.Acceso al recurso -
8919
Study: Time arrow and entropy as evolutionary functions: Natural intelligence (NI) as self-regulation of AI and consciousness within the framework of holistic information theory (H...
Pubblicazione 2026Fuente: ZenodoTipo de material: Recurso digitalAcceso al recurso -
8920
Abundancia relativa de la guitarra Rhinobatos productus (Ayres, 1856) (Pisces: Rhinobatidae) en Bahía Almejas, Baja California Sur, de 1991 a 1995
Pubblicato in Ciencias Marinas (1999)Fuente: Ciencias MarinasTipo de material: Artículo científicoDescripción: Daily commercial fishing data were used to determine the relative abundance of the shovelnose guitarfish Rhinobatos productus (Ayres, 1856) in Bahía Almejas, Baja California Sur (Mexico), from August 1991 to December 1995. Data suggest that seasonal trends exist in the catch, with maximum values from May to August. In order to determine if the seasonality is a result of variations in the abundance, catch effort data (number of nets laid) were included in the calculations and the results were expressed in terms of catch per unit effort (CPUE; org/net/week and org/net/month). The cyclical behavior of R. productus abundance follows lunar cycles, sea temperature and probably food availability, all critical factors if we consider that the species uses the area for its reproduction. The species enters massively into the bay during one month and leaves in just two weeks. An alternate trend was identified in the relative abundance between years, with the uneven years (1993 and 1995) as the abundant ones. The relative abundance of R. productus increased from 1991 to 1995, even with the respective decreases in the even years. Con base en la captura comercial diaria de dos embarcaciones, se determinó la abundancia relativa de la guitarra Rhinobatos productus (Ayres, 1856) en Bahía Almejas, Baja California Sur (México), de agosto de 1991 a diciembre de 1995. Se comprobó que existe una estacionalidad en la captura de la guitarra, con valores máximos de mayo a agosto. Para comprobar si existieron cambios en la abundancia de los organismos, se utilizó el esfuerzo (número de redes tendidas) en los cálculos y se expresaron en unidades de captura por unidad de esfuerzo (CPUE; org/red/semana y org/red/mes). El comportamiento estacional de la abundancia de R. productus en Bahía Almejas obedece a los ciclos lunares, las variaciones térmicas del mar y probablemente a la cantidad de alimento disponible, factores limitantes si se considera que la especie utiliza el área para su reproducción. Es por ello que la entrada de los organismos a la bahía ocurre rápidamente en el transcurso de un mes y la salida se da en sólo dos semanas. Interanualmente, se identificó un patrón alternante, siendo 1993 y 1995 los años que presentaron la mayor abundancia durante el tiempo de estudio. En este sentido, la abundancia relativa de R. productus ha ido en aumento desde 1991, aunque sus números disminuyeron ligeramente en 1992 y 1994.Acceso al recurso