Search Results - temperature (decrease OR increase)
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24261
Morphological composition and fiber partitioning along regrowth in elephant grass CT115 intended for ethanol production
Published 2020Fuente: Universidad del PapaloapanTipo de material: ArtículoDescripción: Leaf share, plant age and growth season are often overlooked as modifiers of the biomass quality in energy crops. The current work studied the effect of the given factors on the biomass yield and the biomass quality in Elephant grass CT115, intended for bioethanol production, in Veracruz, Mexico. Two seasons per year, 5 months each, were tracked on a 2-weeks basis. The climate is warm wet with summer rains, 1,142 mm of annual rainfall, and 26 °C monthly temperature. From day 56 of the wet season or from day 84 of the dry season, stems accumulated 12 or 6 Mg ha−1, respectively, while green leaves increased only 1 Mg. Higher biomass quality was recorded for the leaf fraction, or for the wet season regrowth. For instance, lignin contained in stems meant twice that of leaves, whereas stems recorded 20% less lignin in the wet season as compared to the dry season. Despite holocellulose being similar between fractions or seasons, hemicellulose and cellulose showed inverse correlation, while lignin and cellulose contents were directly correlated in stems. Increasing the annual harvest of green leaves will improve biomass quality, which is known to increase biodegradability and might improve the annual ethanol yield.Acceso al recurso -
24262
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 -
24263
Physicochemical, thermal and rheological properties of three native corn starches
Published 2019Fuente: Universidad del PapaloapanTipo de material: ArtículoDescripción: Native starch was isolated from two corn landraces (blue and white) and a hybrid variety and then characterized for its physicochemical, thermal and rheological properties. The hybrid variety showed the highest starch yield, with its starch showing the highest fat, moisture and protein content but the lowest onset temperature of gelatinization. The hybrid corn starch also showed the highest G’ and G” values. The tested starches showed similar Tp, Tc, and ΔH values. The amylose contents ranged from 21.5 to 22.4%, with starch from blue corn showing the highest amylose content. All starches were white, with L values ranging from 93.6 to 99.5. The light absorbance of the starch gels increased with storage time. The obtained results demonstrated that the physicochemical, thermal and rheological properties of corn starch are highly dependent on the corn type.Acceso al recurso -
24264
Simulación numérica de la hidrodinámica de un puerto y el efecto de un sistema de bombeo por energía de oleaje
Published in Ciencias Marinas (2005)Fuente: Redalyc · Ciencias MarinasTipo de material: Artículo científicoDescripción: A three-dimensional numerical model was adapted to study the circulation, stratification and mixing patterns inside the port of El Sauzal. Salinity, temperature and density field data were measured, showing that density variations were mainly due to the temperature field with a very small contribution from salinity. The model simulated surface currents and the temperature field. The simulation was compared against field data showing that the model reproduces satisfactorily the circulation, stratification and mixing patterns. Surface circulation and vertical mixing were mainly forced by the tide, although winds greater than 6 m s–1 became the main forcing of vertical mixing and surface circulation. The surface currents traveled outside the port during ebb tide and vice versa during flood tide; however, with winds greater than 6 m s–1, the surface velocity followed the wind direction. When a discharge of 0.2 m3 s–1 was introduced into the system, the simulation showed an increase of 0.5 cm s–1 in the surface current velocity, during ebb tide. The vertical temperature structure increased as much as the discharge temperature (17.2ºC). This result verifies that a controlled discharge could improve circulation and mixing, reducing the residence time and improving the levels of oxygen in the water. Con la finalidad de conocer el patrón de circulación, estratificación y mezcla dentro del puerto de El Sauzal, se adaptó un modelo numérico tridimensional. Paralelamente se obtuvieron datos hidrográficos en el puerto de El Sauzal, en los que se encontró a la temperatura como el agente que modifica el campo de densidad, ya que la salinidad tiene poca variación en este sistema. Debido a lo anterior, el modelo simuló solamente el patrón de distribución de temperatura y corrientes. La simulación fue validada con datos de campo, demostrando que el modelo reproduce adecuadamente el patrón de circulación, estratificación y mezcla. El principal forzamiento de la circulación superficial y mezcla vertical en este sistema fue la variación del nivel de mar; sin embargo, el viento superior a 6 m s–1 se convirtió en el principal forzamiento del patrón de circulación y mezcla. Durante la bajamar la dirección de la corriente superficial fue hacia afuera del puerto y viceversa durante la pleamar; sin embargo, cuando el viento tuvo velocidades superiores a 6 m s–1, la dirección de las corrientes siguió la dirección del viento. Durante la bajamar, al introducir una descarga de 0.2 m3 s–1 al sistema, la simulación presentó un incremento de 0.5 cm s–1 en la velocidad de las corrientes superficiales. La estructura vertical de temperatura presentó un incremento generalizado hasta igualar la temperatura de la descarga (17.2ºC). Este resultado indica que una descarga controlada puede ser capaz de mejorar la circulación y mezcla, lo que podría reducir los tiempos de residencia y mejorar los niveles de oxígeno en el agua.Acceso al recurso -
24265
Magnesium Glycinate
Published 2025Fuente: ZenodoTipo de material: Recurso digitalAcceso al recurso -
24266
Effect of Co content on electrochemical hydrogen kinetics properties of single-phase BCC-type MgAlTiCoxNi high entropy alloys used as a negative electrode in basic and acidic elect...
Published 2024Fuente: Universidad del PapaloapanTipo de material: ArtículoDescripción: In this report, the effect of Co content on the electrochemical hydrogen storage reaction kinetic of MgAlTiCoₓNi (x = 1, 1.5 and 2) High Entropy Alloys (HEAs) as negative electrodes under basic (6 M KOH) and acidic (1 M H₂SO₄) electrolyte was studied. Empirical thermodynamic parameters were used to predict the formation of HEAs. The alloys were obtained after 8 h of high-energy ball-milling. The structural analysis showed the formation of a BCC structure and a reduction of the unit lattice with increasing Co content. At high temperatures, the structure changes from BCC-type to B2-type. The morphology and surface area of the MgAlTiCoNi, MgAlTiCo₁.₅Ni, and MgAlTiCo₂Ni alloy powders are very similar. Electrochemical measurements show that alloys exposed to acidic solutions as negative electrodes exhibit higher discharge capacity and better electrochemical hydrogen storage kinetics properties. The increase in Co content in the alloys in both basic and acidic solutions reduced the discharge capacity. Furthermore, a high Co content in the electrodes exposed to an acidic electrolyte reduces the anticorrosion properties of the alloy. The MgAlTiCoNi HEA electrode achieved the best electrochemical performance with a discharge capacity of 465 mAh/g in an acidic electrolyte after a short galvanic charge (60 min). The concentration of Co in the HEAs revealed a direct relationship with the hydrogen diffusion rate, while the lattice parameter is associated with the discharge capacity.Acceso al recurso -
24267
Morphological, barrier, and mechanical properties of banana starch films reinforced with cellulose nanoparticles from plantain rachis
Published 2021Fuente: Universidad del PapaloapanTipo de material: ArtículoDescripción: The main aim of the present study was to characterize banana starch films reinforced with nanoparticles from plantain rachis. Nanoparticles were obtained by acid hydrolysis and sonication, exhibiting a mean hydraulic diameter of about 60 nm. Scanning electron microscopy micrographs showed that the nanoparticle thickness ranged between 9.8 and 22.3 nm. The thermal gravimetric analysis showed that nanoparticles are thermally stable for temperatures up to 340 °C. Films were made for different fractions of nanoparticles (0.0, 1.75, 2.5, and 4.0%) relative to total solids, and glycerol was used as a plasticizer. The influence of the addition of nanoparticles to starch films on the morphology, water vapor permeability (WVP), and mechanical properties of the nanocomposites films was explored. Cellulose nanoparticles reduced the WVP, and increased the tensile strength and flexibility of the starch films. FTIR analysis of films was used to show that nanoparticles improved the molecular organization of starch chains. It was proposed that nanoparticles acted as a crosslinked for starch chains via hydrogen bonding effects.Acceso al recurso -
24268
Keratin modified and functionalized as a reinforcement and nucleation agent of β-polypropylene composites
Published 2022Fuente: Universidad del PapaloapanTipo de material: ArtículoDescripción: A new green β nucleating agent has been obtained from industrial waste. This way, pimelic acid (PA) was chemically supported on treated keratin fibers to promote the β polymorph into a polypropylene matrix using several percentages of reinforcement (0.5, 1.0, and 5.0% w/w). IR spectra suggest a successful functionalization showing the presence of a new band at 1571 cm−1, indicating a bond between PA and the keratin surface. According to the scanning electron spectroscopy, the nucleating agent was homogeneously distributed on the keratin surface. Wide angle X-ray diffraction (WAXD) patterns and differential scanning calorimetry (DSC) curves demonstrate that the functionalized keratin fibers were able to promote a high percentage of β-crystal into the polypropylene matrix (79% and 60%, respectively). The thermomechanical properties were characterized by dynamic mechanical analysis (DMA). At −30°C, the new reinforcement provides an important increase of 25% in the storage modulus compared with the raw polypropylene. The new reinforcement seems to strongly influence the mobility of the amorphous phase, shifting the Tg to higher temperatures.Acceso al recurso -
24269
Recuperación y estado de salud de los corales escleractinios ante el blanqueamiento en el Sistema Arrecifal Veracruzano en el suroeste del Golfo de México
Published in Ciencias Marinas (2025)Fuente: Ciencias MarinasTipo de material: Artículo científicoDescripción: Coral bleaching is caused mainly by heat stress, as the rise in temperature generates increasingly frequent and intense heat waves. In addition to the increase in temperature, sediment contributions in the Veracruz Reef System (VRS) could increase stress and, with it, the susceptibility of corals to bleaching. This work evaluated 2 reefs of the VRS on 2 time scales: (1) in the short term (2022 to 2023), using the bleaching response index (BRI) to assess the recovery of 104 colonies of scleractinian corals on a scale of 1 to 6 and (2) in the medium term (2008 to 2021), through the coral index (CI) to assess the health of the coral community on a scale of 1 to 5. High values reflect better condition of the corals. In addition, the number of bleached colonies was related to degree heating week (DHW) values and sedimentation rates in both periods. We found that the degrees of accumulated heat were the main cause of bleaching events, whereas sediments did not have a direct influence. In 2022, the prevalence of bleaching was 17% with values of 5 DHW, with Montastraea cavernosa, Siderastrea siderea, Siderastrea stellata, and Colpophyllia natans being the most affected species. However, most exhibited an increase in pigmentation within the first 5 months, with BRI values of 5 and 6. During the period of 2008 to 2021, the health of coral communities was classified as good, with CI values of 3.8 and 3.6. The results illustrate that scleractinian corals have been resilient to bleaching events under VRS conditions, highlighting the need to continue with in situ studies of the susceptible species in this study. El blanqueamiento coralino es principalmente causado por estrés térmico, ya que el aumento de temperatura genera olas de calor cada vez más frecuentes e intensas. Además del incremento de temperatura, el aporte de sedimentos en el Sistema Arrecifal Veracruzano (SAV) podría incrementar el estrés y, con ello, la susceptibilidad de los corales al blanqueamiento. Este trabajo evaluó 2 arrecifes del SAV en 2 escalas de tiempo: (1) a corto plazo (2022 al 2023), mediante el índice de respuesta al blanqueamiento (IRB) para evaluar la recuperación de 104 colonias de corales escleractinios con una escala de 1 a 6, y (2) a mediano plazo (2008 al 2021), por medio del índice de coral (IC) para evaluar la salud de la comunidad coralina con una escala de 1 a 5. Valores altos de los índices reflejan un mejor estado de los corales. Se relacionó el número de colonias blanqueadas con valores de degree heating week (DHW) y tasas de sedimentación en ambos periodos. Se obtuvo que los grados de calor acumulado fueron la causa principal de los eventos de blanqueamiento, mientras que los sedimentos no tuvieron una influencia directa. En 2022 la prevalencia de blanqueamiento fue de 17% con valores de 5 DHW, siendo Montastraea cavernosa, Siderastrea siderea, Siderastrea stellata y Colpophyllia natans las especies más afectadas. Sin embargo, la mayoría exhibieron una pigmentación creciente dentro de los primeros 5 meses, con valores del IRB de 5 y 6. Durante el periodo de 2008 a 2021, la salud de las comunidades coralinas se clasificó como buena, con valores del IC de 3.8 y 3.6. Los resultados ilustran que los corales escleractinios han sido resilientes a los eventos de blanqueamiento bajo las condiciones del SAV, resaltando la necesidad de continuar con estudios in situ de las especies susceptibles en este estudio.Acceso al recurso -
24270
Dinámica del carbono inorgánico disuelto en la región de las grandes islas del golfo de California: Influencia de las masas de agua
Published in Ciencias Marinas (2013)Fuente: Ciencias MarinasTipo de material: Artículo científicoDescripción: In the Midriff Islands region (MIR) of the Gulf of California (Mexico), tidal mixing plays a very important role in the distribution of chemical properties. Although the temporal variability of the water masses is linked to the ocean dynamics of this region, its importance has not been considered. This work estimates the effect of water mass dynamics on the spatial distribution and seasonal variation of dissolved inorganic carbon (DIC) in the region, with special emphasis on the Ballenas Channel, during winter 2002, spring 2003, and summer 2004. Gulf of California Water (GCW) was found throughout the area in the first 100 m. Below, Subtropical Subsurface Water (SSW) filled the Delfín, Salsipuedes, and Tiburón basins, while to the southeast it was found between 150 and 350 m. Pacific Intermediate Water did not cross the sills. SSW enriches the surface water of the MIR with DIC when it increases in volume and when mixed with GCW by tidal effects. This contribution decreases towards summertime, when SSW sinks and the volume of GCW increases. In winter, GCW had three water types associated with oceanographic mixing processes and in combination with the presence of SSW. There was a strong DIC vs temperature relationship, which can be applied to analyze the carbon dynamics in the MIR, both at the surface using satellite imagery and vertically to simulate physical processes. En la región de las grandes islas (RGI) del golfo de California la mezcla por mareas juega un papel muy importante en la distribución de propiedades disueltas. Aunque la variabilidad temporal de las masas de agua está ligada con la dinámica oceanográfica de la región, su importancia no ha sido considerada. En este trabajo se estima el efecto de la dinámica de las masas de agua sobre la distribución espacial y variación estacional del carbono inorgánico disuelto (CID) en la RGI, con especial énfasis en el canal de Ballenas, durante el invierno de 2002, la primavera de 2003 y el verano de 2004. El Agua del Golfo de California (AGC) se encontró en toda la superficie en los primeros 100 m de profundidad. Por debajo del AGC, el Agua Subsuperficial Subtropical (ASS) llenó las cuencas Delfín, Salsipuedes y Tiburón, mientras que en el sureste se encontró entre 150 y 350 m. El Agua Intermedia del Pacifico no atravesó los umbrales. Se encontró que el ASS enriquece de CID las aguas superficiales de la RGI cuando aumenta su volumen y cuando se mezcla con el AGC por efecto de las mareas. El aporte disminuye hacia el verano, cuando el ASS se hunde al mismo tiempo que el volumen de AGC aumenta. En invierno, el AGC presentó tres tipos de agua asociadas a los procesos de mezcla y en combinación con la presencia de ASS. Se encontró también que en la RGI la relación CID vs temperatura podría aplicarse en futuros estudios para analizar la dinámica del carbono en la RGI, tanto en la superficie mediante imágenes de satélite como en la vertical para simular procesos físicos.Acceso al recurso -
24271
Defect states and morphological evolution in mechanically processed ZnO + xC nanosystems as studied by EPR and photoluminescence spectroscopy
Published 2016Fuente: Universidad del PapaloapanTipo de material: ArtículoDescripción: An evolution of electron paramagnetic resonance (EPR) and photoluminescence (PL) spectra of various active states (hydrogen donor DH EPR centers, Zn vacancy-related EPR centers , EPR DS centers from shallow donors (g = 1.9640) in ZnOW, Mn2+ ions in ZnOZB, C EPR centers in carbon nanoparticles, forming the near-band-edge (NBE) PL emission, PL emission typical for Zn-, O- and N-enriched ZnOW particles, as well as oxidized carbon nanodots (OCN)) was observed in the mixtures of ZnO + xC nanoparticles during prolonged high-energy mechanical processing (MP) in a hermetically sealed grinding chamber. The results of EPR and PL spectroscopy, X-ray diffraction analysis, as well as morphological analysis by means of atomic force microscopy (AFM) and laser particle sizer (LPS) measurements show a wide variety of interrelated series–parallel processes in the samples with increasing MP processing time (tMP). These processes include: (a) dramatic reduction in intensity of the DH EPR signal and PL bands at 3.14 (1.57), 2.53 and 2.3 eV during the first minutes of MP, which correlate with sample disaggregation; (b) grinding of ZnO particles and formation of Zn vacancy-related EPR centers in the area of destruction (AD); (c) an increase in sample temperature; (d) annealing of the Zn vacancy-related EPR centers formed; (e) initiation of carbon nanoparticle interaction with oxygen in the grinding chamber; (f) formation and growth of the EPR signal due to carbon nanoparticles; (g) formation of a reducing environment in the grinding chamber; (h) stabilization of donor DS-centers in AD of ZnO nanoparticles; (i) an increase in CO concentration in the grinding chamber; (j) inhibition of DS paramagnetic centers in ZnO; (k) initiation of the EPR signals due to Mn2+ ions in ZnOZB sphalerite phase in the sample with the lowest carbon content; (l) inhibition of nitrogen PL centers in ZnO; (m) the formation of oxidized carbon nanodots (OCN) showing a PL band at 2.8 eV. A detailed analysis for the localization of EPR and PL centers in the MP samples is presented.Acceso al recurso -
24272
Potencial de engorda postcriadero de Penaeus vannamei en un sistema intensivo tipo "raceway"
Published in Ciencias Marinas (1992)Fuente: Ciencias MarinasTipo de material: Artículo científicoDescripción: A 49-day intensive growth trial in 70 m2 raceways under a greenhouse was conducted with Penaeus vannamei (stocked at an average weight of 80 mg and density of 223-299 ind./m2). Shrimp grew at an average rate of 0.94 to 1.19 g/week. They were harvested at a mean size of 6.5 to 8.1 g with the biomass produced reaching 1.36 to 1.56 kg/m2 and survival ranging from 78 to 83%. As biomass increased, the management of water recirculation and water exchange became more intensified. Seawater was replaced initially at a rate of 3%/day and increased to 400% daily during the final week of the study. Although this trial was undertaken during the spring in Texas when ambient morning water temperatures ranged from 18.3 to 28.3ºC, temperatures in the raceways were maintained with a mean daily low temperature of 26.8ºC and mean daily high of 29.8ºC. Shrimp cultured simultaneously in outdoor ponds were smaller (4.3 to 5.0 g) and had lower growth (0.62 to 0.71 g/week). Results obtained in this trial indicate that a larger juvenile can be produced for pond stocking and suggest that P. vannamei can be cultured successfully in this intensive raceway system to a marketable size. Se realizó una prueba de engorda intensiva de 49 días de duración en estanques tipo “raceway” de 70 m2 con Penaeus vannamei, sembrados con un peso promedio de 80 mg y a una densidad de 223-299 ind./m2. Los camarones mostraron una tasa de crecimiento promedio de 0.94 a 1.19 g/semana. Fueron cosechados a un tamaño promedio de 6.5 a 8.1 g. La biomasa producida alcanzó 1.36 a 1.56 kg/m2 y la supervivencia varió de 78 a 83%. Al incrementar la biomasa, se intensificó el manejo de la recirculación y el recambio de agua. El agua de mar se reemplazó inicialmente a una tasa de 3% por día y se incrementó hasta 400% por día durante la última semana del estudio. Aunque se realizó esta prueba durante la primavera en Texas cuando la temperatura ambiente del agua varió de 18.3 a 28.3ºC en la manaña, se mantuvo la temperatura en los “raceways” en un promedio mínimo diario de 26.8ºC y un promedio máximo diario de 29.8ºC. Los camarones cultivados simultáneamente en estanques al aire libre fueron más pequeños (4.3 a 5.0 g) y tuvieron un crecimiento menor (0.62 a 0.71 g/semana). Los resultados obtenidos indican que se puede producir un juvenil mayor para la siembra de estanques y sugieren que se puede cultivar P. vannamei exitosamente en este sistema tipo “raceway” hasta un tamaño comercial.Acceso al recurso -
24273
The Nexus Framework: Recursive Harmonic Genesis and the Digital Substrate of Reality
Published 2026Fuente: ZenodoTipo de material: Recurso digitalAcceso al recurso -
24274
Abundancia relativa de la guitarra Rhinobatos productus (Ayres, 1856) (Pisces: Rhinobatidae) en Bahía Almejas, Baja California Sur, de 1991 a 1995
Published 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 -
24275
Preengorda del Ostión Americano (Crassostrea virginica) en lagunas costeras tropicales en Yucatán, México: modelación de regresión no lineal y relaciones con variables ambientales...
Published 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 -
24276
Growth, yield, fiber content and lodging resistance in eight varieties of Cenchrus purpureus (Schumach.) Morrone intended as energy crop
Published 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 -
24277
Variación anual de la productividad del fitoplancton en el Estero de Punta Banda, B.C.
Published in Ciencias Marinas (1991)Fuente: Ciencias MarinasTipo de material: Artículo científicoDescripción: Eleven time series were carried out at one station in Estero de Punta Banda, from June 1987 to May 1988. The samples were taken during the day at spring and neap tides and the following variables were analysed: temperature, salinity, concentration of phosphates, nitrates, silicates and chlorophyll a. Two primary productivity experiments were conducted with the carbon-fourteen method for each sampling. The maximum temperature, 22.16ºC, occurred in summer and the minimum, 16.33ºC, in winter. Both the amplitude of variation and the chlorophyll a concentration were higher in summer. The average of the concentration of nitrates and phosphates of each sampling was very similar throughout the year, except in January due to a storm that caused mixing and homogenization in the water column of the bay, causing the concentration to increase during the flow of the tidal current in the Estero. Primary productivity was higher during the summer months, reaching values of up to 68.32 mgC/ms/h, and lower in autumn and winter with values of 3.57 mgC/m3/h. High assimilation ratio values are reported during neap tides. Se realizaron 11 series de tiempo en una estación del estero de Punta Banda, de junio de 1987 a mayo de 1988. Se muestreó en el día en mareas vivas y muertas, analizando las siguientes variables: temperatura, salinidad, concentración de fosfatos, nitratos, silicatos y clorofila a. Se realizaron dos experimentos de productividad primaria con el método de carbono catorce en cada muestreo. La temperatura presentó sus valores máximos en verano con 22.16º y un mínimo en invierno de 16.33ºC. Tanto la amplitud de variación como la concentración de clorofila a fue mayor en verano. El promedio de la concentración de los nitratos y fosfatos de cada muestreo fue muy similar durante todo el año, excepto en enero debido a la tormenta que provocó mezcla y homogeneización de la columna de agua de la bahía, incrementándose la concentración durante el flujo de la corriente de marea en el estero. La productividad primaria fue mayor en los meses de verano, alcanzando valores hasta de 68.32 mgC/ms/h y mínimos en otoño e invierno con valores de 3.57 mgC/ms/h. Altos valores de razón de asimilación se reportan durante las mareas muertas.Acceso al recurso -
24278
Hidrografía en la Boca Norte de la Bahía de La Paz, Baja California Sur, México
Published 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 -
24279
The Nexus Recursive Harmonic Architecture: Comprehensive Remediation and Technical Specification
Published 2026Fuente: ZenodoTipo de material: Recurso digitalAcceso al recurso -
24280
The Logical Reality of SHA-256 Reversibility: A Comprehensive Analysis via Dual-Wave Theory and the Twin Prime Policy Constraint
Published 2026Fuente: ZenodoTipo de material: Recurso digitalAcceso al recurso