Surface Water Turbidity in the Entrance to Chesapeake Bay, Virginia

Seasonal and spatial variations in the surface water turbidity across the entrance to Chesapeake Bay, Virginia, have been monitored with an optical transmissometer for one year. The data indicate a suspended-sediment gradient across the entrance with higher turbidity on the south side. This condition suggests that the flooding and ebbing tidal currents are influenced by Coriolis force. Clearer ocean water is introduced into the bay on the north side; whereas highly turbid water from the major drainage systems exits on the south side. A salinity gradient with18 0/00 on the south side of the bay and approximately 32 0/00 on the north side supports this hypothesis. The suspended-sediment gradient is modified by a two-season regime. The winter season extends from October through March, and the summer season from April through September. The winter season is characterized by a higher turbidity, is initiated by a fall diatom bloom, and is maintained by extended periods of high wind. The summer season is characterized by low turbidity, is initiated by the dying-off of a late winter-early spring diatom bloom, and is maintained by extended periods of calm weather

Giant freshwater prawn farming in the Philippines

Freshwater prawn thrives in inland waters like rivers, lakes, swamps, irrigation canals, estuaries and even in rivers upstream. A recent survey in Luzon Island, Philippines identified 12 species of freshwater prawn found in the island (Agasen, unpublished). The country’s interest on freshwater prawn fishery started in 1914 as explained by Cowles (1914), when the freshwater prawn was recognized as one of the important fisheries during that time. In late 1976, trials were made to culture the freshwater prawn, however, the efforts were not sustained. These trials were conducted in Misamis Oriental, Mindanao between 1976-1979 by Dejarme et al., with the collection of wild spawners and the subsequent rearing of M. rosenbergii hatchlings. In 1981, a local banker-industrialist established a 100-hectare commercial Macrobrachium farm in Sta. Rosa, Nueva Ecija and a hatchery in Bulacan. Services of experts from Israel were tapped for the project. Marketable prawns were sold live in Metro Manila utilizing in-house retail outlets. After a few years, the company diversified their operations to include tilapia culture. However, even the diversification attempt failed to save the first venture of commercial Macrobrachium rosenbergii production in the Philippines

THE EFFECTS OF ECCENTRIC PHASE DURATION ON CONCENTRIC PHASE FORCE PRODUCTION DURING DEPTH JUMPS

The purpose of the study was to test the yet unproven theory, which states that the faster a muscle is stretched the greater force it produces in the subsequent concentric phase during plyometric exercises. Thirty-three trained male athletes performed plyometric depth jumps from two heights (trial A=33.02cm, trial B=47.94cm) landing on a force platform, followed by an immediate counter jump. Researchers determined the duration of eccentric phase and the relative peak concentric force of each jump using the data from the force platform. Results indicated a significant inverse relationship between eccentric duration and relative peak concentric force in both trials (p=0.019 and

The Feminist Itinerant School: A Feminist Pedagogical Approach to Curriculum Transformation for Public School Teachers in Brazil

This Thesis examines Brazil’s political and historical context to explore and understand the logics behind the high rates of violence in our society. It focuses in education as one of our main vehicles of disseminating knowledge and therefore culture, language and values that might be contributing and perpetuating sexism, racism, and classism. It argues and emphasizes the importance of feminist and critical pedagogies to bring different perspectives to the curriculum through a literature review that has guided the development of the suggested workshop for public schools’ teacher. The workshop named The Itinerant Feminist school intents to reflect upon social cultural and political issues that directly affects students’ lives and our teaching practices. Opening a space for teacher to share their own concerns in the classroom at the same time as exploring and understanding how privilege, positionality and implicit bias might be embedded in our practices

Propiedades de transmisión de electrones de Dirac a través de superredes Cantor en grafeno

En este trabajo usamos el método de la matriz de transferencia para estudiar el tunelamiento de los electrones de Dirac a través de superredes aperiodicas en grafeno. Consideramos una hoja de grafeno depositada encima de bloques de sustratos de Óxido de Silicio (SiO2) y Carburo de Silicio (SiC), en los cuales aplicamos la serie de Cantor. Calculamos la transmitancia para diferentes parámetros fundamentales tales como: ancho de partida, energía de incidencia, ángulo de incidencia y número de generación de la serie de Cantor. En este caso, la transmitancia como función de la energía presenta rasgos autosimilares al variar el número de generación. También computamos la distribución angular de la transmitancia para energías fijas econtrando un patrón autosimilar entre generaciones. Por último, calculamos los factores de escala para algunos espectros de la transmitancia, los cuales efectivamente muestran escalabilidad.In this work we use the transfer matrix method to study the tunneling of Dirac electrons through aperiodic monolayer graphene superlattices. We consider a graphene sheet deposited on top of slabs of Silicon-Oxide (SiO2) and Silicon-Carbide (SiC) substrates, in which we applied the Cantor's series. We calculate the transmittance for different fundamental parameters such as: starting width, incident energy, incident angle and generation number of the Cantor's series. In this case, the transmittance as function of energy presents self-similar features as a function of the generation number. We also compute the angular distribution of the transmittance for fixed energies finding a self-similar patterns between generations. Finally, we calculate the scaling factor for some transmittance spectra, which effectively show scalability

Propiedades de transmisión de electrones de Dirac a través de superredes Cantor en grafenoTransmission properties of Dirac electrons through Cantor monolayer graphene superlattices

In this work we use the transfer matrix method to studythe tunneling of Dirac electrons through aperiodic monolayer graphene superlattices. We consider a graphene sheet deposited on top of slabs of Silicon-Oxide (SiO2) and Silicon-Carbide (SiC) substrates, in which we applied the Cantor’s series. We calculatethe transmittance for different fundamental parameters such as: starting width, incident energy, incident angle and generation number of the Cantor’s series. In this case, the transmittance as function of energy presents self-similar features as a function of the generation number. We also compute the angular distribution of the transmittance for fixed energies finding a self-similar patterns between generations. Finally, we calculate the scaling factor for some transmittance spectra, which effectively show scalability.En este trabajo usamos el método de la matriz de transferencia para estudiar el tunelamiento de los electrones de Dirac a través de superredes aperiodicas en grafeno. Consideramosuna hoja de grafeno depositada encima de bloques de sustratos de Óxido de Silicio (SiO2) y Carburo de Silicio (SiC), en los cuales aplicamos la serie de Cantor. Calculamos la transmitancia para diferentes parámetros fundamentales tales como: ancho de partida, energía de incidencia, ángulo de incidencia y número de generación de la serie de Cantor. En este caso, la transmitancia como función de la energía presenta rasgos autosimilares al variar el número de generación. También computamos la distribución angular de la transmitancia para energías fijas econtrando un patrón autosimilar entre generaciones. Por último, calculamos los factores de escala para algunos espectros de la transmitancia, los cuales efectivamente muestran escalabilida

Identity of the Silyl Ligand in an Iron Silyl Complex Influences Olefin Hydrogenation: An Experimental and Computational Study

Producción CientíficaIn this study, we explore the selective synthesis of iron silyl complexes using the reaction of an iron mesityl complex (MesCCC)FeMes(Py) with various hydrosilanes. These resulting iron silyl complexes,(MesCCC)Fe(SiH2Ph)(Py)(N2), (MesCCC)-Fe(SiMe2Ph)(Py)(N2), and (MesCCC)Fe[SiMe(OSiMe3)2](Py)-(N2), serve as effective precatalysts for olefin hydrogenation. The key to their efficiency in catalysis lies in the specific nature of the silyl ligand attached to the iron center. Experimental observations, supported by density functional theory (DFT) simulations, reveal that the catalytic performance correlates with the relative stability of dihydrogen and hydride species associated with each iron silyl complex. The stability of these intermediates is crucial for efficient hydrogen transfer during the catalytic cycle. The DFT simulations help to quantify these stability factors, showing a direct relationship between the silyl ligand’s electronic and steric properties and the overall catalytic activity. Complexes with certain silyl ligands exhibit better performance due to the optimal balance between the stability and reactivity of the key active catalyst. This work highlights the importance of ligand design in the development of ironbased hydrogenation catalysts.A.R.F. and D.C.N. thank NSF CHE 232496 and PD Soros for funding. We also acknowledge the DJEI/DES/SFI/HEA Irish Centre for High-End Computing (ICHEC) for the provision of computational resources. M.N.P.D. thanks the UVa for a Margarita Salas fellowship (ref CONVREC-2021-221)

Distribución del sistema del carbonato al sur de las Islas Canarias en la primavera del año 2000

The measurement of the surface molar fraction of CO2 (atmosphere and sea water) and water column pHT, total alkalinity, AT, nutrients and oxygen were carried out in spring 2000 at the European Station for Time Series in the Ocean at the Canary Islands (ESTOC) and in the area located south of the Canary Islands. The significant eddy field strongly affecting the pattern of the chemical and carbonate system variables is presented and discussed. A mixing model based on the thermohaline properties of the water masses was established. The model explained over 97% of the variability found in the distribution of the chemical variables. Intermediate waters to the south of the Canary Islands show a high contribution of Antarctic waters with about 5% of pure Antarctic Intermediate Water. Moreover, the surface structure affected the atmosphere-ocean carbon dioxide exchange, making the area act as a CO2 sink taking up 9.1 mmol m-2 week-1, corresponding to 0.03 Mt of CO2 which were taken up by the area in a week at the end of March 2000.Durante la primavera del año 2000 se realizaron medidas en las aguas superficiales de la fracción molar de CO2 (atmósfera y océano) y en la columna de agua de pHT, alcalinidad total, AT, nutrientes y oxígeno, para la Estación Europea Oceánica de Series Temporales de Canarias (ESTOC) y al sur de las islas Canarias. En este trabajo se presenta y discute el efecto del importante campo de remolinos presente en el área sobre la distribución de las variables químicas y del sistema de carbonato. Se ha establecido un modelo de mezcla, basado en las propiedades termohalinas de las diferentes masas de agua, que explica el 97% de la variabilidad encontrada en la distribución de las variables químicas. Las aguas intermedias al sur de las islas Canarias están caracterizadas por la alta contribución del agua Antártica intermedia diluida, que corresponde con una contribución próxima al 5% de agua Antártica intermedia pura. Por otro lado, las estructuras superficiales afectan al intercambio de CO2 atmósfera-océano, actuando el área como un sumidero de dióxido de carbono incorporando 9.1 mmol m-2 semana-1, que se corresponde con 0.03 MTon de CO2 captadas por el área y en una semana a finales de marzo del 2000

Sustainable electrosynthesis of cyclohexanone oxime through nitrate reduction on a Zn-Cu alloy catalyst

Cyclohexanone oxime is an important precursor for Nylon-6 and is typically synthesized via the nucleophilic addition-elimination of hydroxylamine with cyclohexanone. Current technologies for hydroxylamine production are, however, not environment-friendly due to the requirement of harsh reaction conditions. Here, we report an electrochemical method for the one-pot synthesis of cyclohexanone oxime under ambient conditions with aqueous nitrate as the nitrogen source. A series of Zn-Cu alloy catalysts are developed to drive the electrochemical reduction of nitrate, where the hydroxylamine intermediate formed in the electroreduction process can undergo a chemical reaction with the cyclohexanone present in the electrolyte to produce the corresponding oxime. The best performance is achieved on a Zn93Cu7 electrocatalyst with a 97% yield and a 27% Faradaic efficiency for cyclohexanone oxime at 100 mA/cm2. By analyzing the catalytic activities/selectivities of the different Zn-Cu alloys and conducting in-depth mechanistic studies via in situ Raman spectroscopy and theoretical calculations, we demonstrate that the adsorption of nitrogen species plays a central role in catalytic performance. Overall, this work provides an attractive strategy to build the C-N bond in oxime and drive organic synthesis through electrochemical nitrate reduction, while highlighting the importance of controlling surface adsorption for product selectivity in electrosynthesis