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Castaño Serna, Juan Pablo, Ainhoa Rubio Clemente, and Edwin Chica Arrieta. "Evaluación de superficies reflectantes para paneles solares bifaciales mediante la metodología de superficie respuesta." Ingeniería 27, no. 3 (August 12, 2022): e18069. http://dx.doi.org/10.14483/23448393.18069.
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Contexto: Los paneles solares fotovoltaicos bifaciales pueden generar más energía que los monofaciales, ya que, en el primer caso, ambos lados del panel quedan a disposición para captar la irradiancia solar y transformarla en energía eléctrica. La potencia adicional que se puede generar en los paneles bifaciales depende, entre otros factores, de la naturaleza y el tipo de la superficie reflectiva, así como de la orientación del módulo fotovoltaico. Método: En este trabajo se evalúan diversas superficies reflectantes para determinar la configuración óptima de un panel bifacial. Para este propósito, y con base en la metodología de superficie de respuesta, las curvas características del panel fotovoltaico (corriente-voltaje) para diversas elevaciones con respecto a cuatro superficies reflectantes son trazadas experimentalmente. Resultados: Los resultados del estudio revelan que, al instalar un panel bifacial sobre superficies reflectantes de espejo a una elevación del 98,66 % del ancho del panel, se logra alcanzar un aumento del 6,6 % de la generación de energía eléctrica en comparación con los módulos fotovoltaicos monofaciales. Conclusiones: Con la metodología aplicada, se identificó que la superficie de espejo es la mejor de las cuatro superficies evaluadas para el aprovechamiento de la irradiación reflejada, seguida por el concreto, el agua y la tierra.
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Aydin, İbrahim, Ali İhsan Bahçepinar, and Canser Gül. "Caracterización de la superficie de un recubrimiento EPD sobre la aleación de Mg AZ91 obtenida mediante Pulvimetalurgia." Revista de Metalurgia 56, no. 3 (September 30, 2020): 176. http://dx.doi.org/10.3989/revmetalm.176.
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Los implantes habituales en aplicaciones biomédicas como el Ti y sus aleaciones y el acero inoxidable 316L pueden dañar los tejidos circundantes, ocasionando infecciones. Para evitar este riesgo, es necesario producir materiales de implantes de nueva generación que sean más ligeros que los biomateriales existentes, en los que las propiedades mecánicas y estructura sean similares al hueso. En este estudio, el material de implante de aleación de Mg AZ91 se obtiene mediante un procedimiento pulvimetalúrgico. Adicionalmente, para mejorar la biocompatibilidad y bioactividad, el material de implante obtenido se recubrió con hidroxiapatita (HA), conocido como biomaterial de base cerámica. Se aplicó un revestimiento de HA a la superficie de la aleación utilizan el método de deposición electroforética. Se examinaron las propiedades superficiales y la resistencia a la corrosión. Los valores de voltaje aplicados en el proceso de recubrimiento fueron 100, 150, 200 y 250 V, durante un tiempo de 2 min. Se utilizaron productos químicos de HA, etanol, alcohol polivinílico (PVA), N, N-dimetilformamida para preparar la solución de revestimiento. Se analizaron las microestructuras de los recubrimientos mediante microscopía electrónica de barrido (SEM) y se realizaron análisis elementales (EDS) de las superficies del recubrimiento. Se utilizó el método de difracción de rayos X (XRD) para determinar las fases de los recubrimientos y su concentración. Finalmente, se determinaron los valores de espesor del revestimiento y la rugosidad superficial. El comportamiento frente a la corrosión se determinó mediante la medida de potencial de corrosión, utilizando como electrolito un fluido corporal artificial.
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Naik, Subhashree, Sudhansu Ranjan Das, Debabrata Dhupal, and Ajit Kumar Khatua. "Análisis de la integridad de la superficie y evaluación de la sostenibilidad en el mecanizado por electroerosión de un material compuesto de matriz metálica ingenieril Al-22% SiC." Revista de Metalurgia 57, no. 4 (December 30, 2021): e210. http://dx.doi.org/10.3989/revmetalm.210.
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En vista de las amplias aplicaciones que tienen los materiales compuestos ingenieriles de matriz metálica, particularmente en las industrias automotriz, eléctrica y aeroespacial, dar forma a estos materiales es un desafío realmente difícil. Esta investigación aborda el mecanizado por electroerosión de un material compuesto de matriz metálica Al-22% SiC para analizar la rugosidad de la superficie de las piezas mecanizadas. Se realizan una serie de pruebas de mecanizado en diversas condiciones de procesado (presión de chorro, voltaje, tiempo de activación del pulso, corriente de descarga, tiempo de desactivación del pulso) obtenido por un diseño Box- Behnken. Adicionalmente, este trabajo aborda la metodología de optimización deseada y modelado predictivo para la minimización de la calidad de la superficie mecanizada empleando la metodología de superficie de respuesta. Basado en el punto de vista motivacional de “Sea verde-piense en verde-actúe en verde”, se ha sugerido un enfoque único para el análisis económico y la evaluación de sostenibilidad para determinar el costo total de mecanizado por pieza y para justificar la utilidad del aceite vegetal como medio dieléctrico en el proceso de electroerosión. De acuerdo con este análisis estadístico, la contribución de la corriente de descarga de chispa se identificó como el factor principal en la degradación de la calidad de la superficie. El valor de rugosidad superficial óptima estimado (Ra) de 0,181 µm y el coste total de mecanizado calculado por pieza de Rs. 245,9 (2,95 €) se prefirieron con un tiempo de activación del pulso de 100 µs, voltaje de 1 V, tiempo de desactivación de pulso de 30 µs, corriente de descarga de 4 A y presión de lavado de 0,056 MPa, lo que indica que es tecno-económicamente viable. El aceite vegetal considerado como fluido dieléctrico es biodegradable, ambientalmente seguro y, por tanto, contribuye a tener una producción sostenible. Los datos de mecanizado de este material compuesto Al-SiC serían beneficiosos para la industria.
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Guerra, Fernanda Lamego, Eduardo Grala da Cunha, Antônio César Silveira Baptista da Silva, and Stífany Knop. "Análise das condições favoráveis à formação de bolor em edificação histórica de Pelotas, RS, Brasil." Ambiente Construído 12, no. 4 (December 2012): 7–23. http://dx.doi.org/10.1590/s1678-86212012000400002.
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Considerando a relevância do desenvolvimento de estudos que visam a compreender as condições ambientais favoráveis à formação do bolor, este artigo apresenta uma análise do desempenho da superfície interior de uma parede voltada ao exterior em uma edificação histórica na cidade de Pelotas, RS. A superfície selecionada apresentava formação de bolor, confirmada por uma análise microbiológica. Com o objetivo de compreender as condições ambientais que favoreceram a formação do bolor na superfície naquele ambiente, foram aplicados dois métodos de análise das condições higrotérmicas da superfície: o primeiro considera o regime de transferência de calor estacionário; e o segundo, por simulação computacional, considera o regime de transferência de calor transiente. Os resultados obtidos confirmaram a possibilidade da formação de bolor, levando em conta, principalmente, os aspectos de umidade próxima à superfície da parede e temperatura superficial interna. Para o desenvolvimento desta análise foram consideradas as observações das normas brasileiras NBR 15220: desempenho térmico de edificações: parte 2 (ABNT, 2005), da NBR 15575: edificações habitacionais de até cinco pavimentos (ABNT, 2008b) e da norma alemã DIN 4108-3: isolamento térmico e economia de energia em edifícios (2001).
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Xing, Yong Ming, and Satoshi Kishimoto. "Fabrication of Superfine Electron Moiré Grid." Key Engineering Materials 326-328 (December 2006): 111–14. http://dx.doi.org/10.4028/www.scientific.net/kem.326-328.111.
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The electron moiré method uses a high frequency grating to measure microscopic deformation. Finer and finer gratings are being pursued to meet higher and higher resolution requirements in microscopic stress analysis. In this study, the techniques of fabricating electron grid by means of a scanning electron microscope are improved. The use of a low accelerating voltage shows a better effect than the high accelerating voltage in fabricating a superfine grid. A new group of parameters is suggested based on this consideration. A cross-line grid with a frequency of 10,000 lines/mm and a parallel grating with a frequency of 13,000 lines /mm have been successfully fabricated.
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Fan, S., M. Stewart, and R. K. Wong. "Differences in voltage-dependent sodium currents exhibited by superficial and deep layer neurons of guinea pig entorhinal cortex." Journal of Neurophysiology 71, no. 5 (May 1, 1994): 1986–91. http://dx.doi.org/10.1152/jn.1994.71.5.1986.
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1. Sodium currents were studied using whole-cell voltage-clamp techniques in neurons acutely isolated from superficial (II/III) and deep (V/VI) layers of guinea pig entorhinal cortex. 2. Sodium currents were larger (peak amplitude) in superficial than in deep layer cells under the same conditions: -1939 +/- 780 (SD) pA (N = 6) versus -307 +/- 257 pA (N = 6). Specific membrane conductance was calculated to be 12.3 +/- 9.6 mS/cm2 for superficial layer cells and 1.4 +/- 0.9 mS/cm2 for deep layer cells. 3. Sodium currents could be activated in superficial layer cells from potentials as depolarized as -20 mV, whereas no significant currents could be activated in deep neurons from potentials more depolarized than about -50 mV. Using a protocol consisting of a 25-ms prepulse and a 20 ms test pulse, the inactivation curves for superficial layer cells were found to be shifted toward more depolarized potentials by an average of 15 mV (V50 = -59.8 +/- 3.8 mV compared with -75.7 +/- 12.0 mV for deep cells). This produced a region of overlap with the activation curves for superficial cells. 4. Over a range of about -50 to -20 mV in superficial layer cells, the region of overlap of the activation and inactivation curves, a sodium current could be activated, which did not fully inactivate during the test pulse (average peak amplitude: -89.5 +/- 48.7 pA; crossover voltage: -39.2 +/- 2.0 mV). Voltage steps to more depolarized potentials, outside the voltage “window”, permitted complete inactivation of the sodium current.(ABSTRACT TRUNCATED AT 250 WORDS)
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Du, Ai Min, Chu Chuan Chu, and Zhong Pan Zhu. "Development of Test Bench for Durability of Ignition Coil Based on Labview." Advanced Materials Research 1006-1007 (August 2014): 697–702. http://dx.doi.org/10.4028/www.scientific.net/amr.1006-1007.697.
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The primary current, the secondary voltage and superficial temperature of ignition coil witness characterization of work performance of the ignition coil. In this paper an ignition coil testing platform based on Labview is developed. The real-time performance parameters of the ignition coil are acquired by data acquisition card,high voltage probe, STM32 micro controller which include the primary current, the secondary voltage and superficial temperature of ignition coil. The results indicate that the testing bench significantly improves the collection of ignition coil performance parameters.
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Uribe Martínez, Jorge Mario, Leidy Johana Quintero Rodríguez, Liliana Tirado-Mejía, and Francisco Javier Ibargüen. "ACONDICIONAMIENTO Y DIGITALIZACIÓN DE LA SEÑAL DE UN LVDT PARA LA MEDICIÓN DEL PERFIL DE UNA SUPERFICIE SÓLIDA Acondicionamiento y Digitalización de un LVDT." Revista de Investigaciones Universidad del Quindío 25, no. 1 (March 28, 2014): 113–19. http://dx.doi.org/10.33975/riuq.vol25n1.160.
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El LVDT es el elemento más importante para la medición de los perfiles utilizando un perfilómetro de contacto y su función es convertir las variaciones de desplazamiento de una aguja en variaciones de voltaje, a través del desplazamiento del núcleo de una bobina acoplado a la aguja. El desplazamiento del núcleo a escala completa se determinó midiendo el recorrido total que hace la aguja, obteniendo el mismo voltaje en el secundario para los desplazamientos extremos. Con este valor y con el de los voltajes del primario y secundario se encontró una alta sensibilidad para el LVDT del perfilómetro, siendo 7,19mV/V/mil el valor obtenido, lo que significa un reto para su lectura. Para el acondicionamiento del LVDT se utilizó un circuito AD698 que genera una señal oscilante, con amplitud y frecuencia ajustable para el primario, y un demodulador síncrono que convierte la señal del secundario en una señal DC, que incrementa linealmente con respecto a la posición del núcleo. Se diseñó e implementó un sistema de conversión A/D, teniendo en cuenta la resolución, la señal de entrada, la frecuencia de muestreo, las prestaciones estáticas y las dinámicas, la interfaz de comunicación, y el tamaño y el precio. La transmisión de los datos de la medida del perfil se realizó por medio del protocolo USB, a través de un microcontroladorATxmega. Se realizaron medidas del perfil utilizando unas muestras patrón de 50, 5 y 1 KÅ, para evaluar el desempeño del sistema de acondicionamiento, obteniéndose resultados satisfactorios.
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Pontes, K. C. S., A. P. B. Borges, T. S. Duarte, G. L. Morato, V. Zavan, R. B. Eleotério, and E. C. Carlo. "Membrana amniótica canina utilizada como bandagem em úlcera superficial de córnea de coelhos: aspectos clínicos." Arquivo Brasileiro de Medicina Veterinária e Zootecnia 60, no. 5 (October 2008): 1069–74. http://dx.doi.org/10.1590/s0102-09352008000500005.
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Realizou-se a ceratectomia superficial em 28 coelhos, distribuídos em dois grupos. No grupo tratado, composto por 14 animais, utilizou-se a membrana amniótica canina como bandagem, suturada com sua face epitelial voltada contra a superfície corneana. O grupo controle não recebeu tratamento. A avaliação clínica foi realizada 24 horas após a cirurgia, a cada dois dias durante uma semana e a cada quatro dias até 180 dias. Avaliaram-se os efeitos da membrana amniótica como bandagem, comparando-se o tempo de epitelização da córnea entre os grupos e verificando o período necessário para que a córnea apresentasse transparência completa. A opacidade corneana esteve presente em todos os animais durante o período observado. O tratamento instituído resultou clinicamente em neovascularização corneana, opacidade de córnea mais intensa no período inicial de reparação, retardou o processo de epitelização e causou mais dor e desconforto que nos animais do grupo-controle.
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Gibor, Gilad, Daniel Yakubovich, Asher Peretz, and Bernard Attali. "External Barium Affects the Gating of KCNQ1 Potassium Channels and Produces a Pore Block via Two Discrete Sites." Journal of General Physiology 124, no. 1 (June 28, 2004): 83–102. http://dx.doi.org/10.1085/jgp.200409068.
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The pore properties and the reciprocal interactions between permeant ions and the gating of KCNQ channels are poorly understood. Here we used external barium to investigate the permeation characteristics of homomeric KCNQ1 channels. We assessed the Ba2+ binding kinetics and the concentration and voltage dependence of Ba2+ steady-state block. Our results indicate that extracellular Ba2+ exerts a series of complex effects, including a voltage-dependent pore blockade as well as unique gating alterations. External barium interacts with the permeation pathway of KCNQ1 at two discrete and nonsequential sites. (a) A slow deep Ba2+ site that occludes the channel pore and could be simulated by a model of voltage-dependent block. (b) A fast superficial Ba2+ site that barely contributes to channel block and mostly affects channel gating by shifting rightward the voltage dependence of activation, slowing activation, speeding up deactivation kinetics, and inhibiting channel inactivation. A model of voltage-dependent block cannot predict the complex impact of Ba2+ on channel gating in low external K+ solutions. Ba2+ binding to this superficial site likely modifies the gating transitions states of KCNQ1. Both sites appear to reside in the permeation pathway as high external K+ attenuates Ba2+ inhibition of channel conductance and abolishes its impact on channel gating. Our data suggest that despite the high degree of homology of the pore region among the various K+ channels, KCNQ1 channels display significant structural and functional uniqueness.
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Blankenship, M. L., D. E. Coyle, and M. L. Baccei. "Transcriptional expression of voltage-gated Na+ and voltage-independent K+ channels in the developing rat superficial dorsal horn." Neuroscience 231 (February 2013): 305–14. http://dx.doi.org/10.1016/j.neuroscience.2012.11.053.
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Nixima, Ken'ichi, Kazuo Okanoya, Noritaka Ichinohe, and Tohru Kurotani. "Fast voltage-sensitive dye imaging of excitatory and inhibitory synaptic transmission in the rat granular retrosplenial cortex." Journal of Neurophysiology 118, no. 3 (September 1, 2017): 1784–99. http://dx.doi.org/10.1152/jn.00734.2016.
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Rodent granular retrosplenial cortex (GRS) has dense connections between the anterior thalamic nuclei (ATN) and hippocampal formation. GRS superficial pyramidal neurons exhibit distinctive late spiking (LS) firing property and form patchy clusters with prominent apical dendritic bundles. The aim of this study was to investigate spatiotemporal dynamics of signal transduction in the GRS induced by ATN afferent stimulation by using fast voltage-sensitive dye imaging in rat brain slices. In coronal slices, layer 1a stimulation, which presumably activated thalamic fibers, evoked propagation of excitatory synaptic signals from layers 2–4 to layers 5–6 in a direction perpendicular to the layer axis, followed by transverse signal propagation within each layer. In the presence of ionotropic glutamate receptor antagonists, inhibitory responses were observed in superficial layers, induced by direct activation of inhibitory interneurons in layer 1. In horizontal slices, excitatory signals in deep layers propagated transversely mainly from posterior to anterior via superficial layers. Cortical inhibitory responses upon layer 1a stimulation in horizontal slices were weaker than those in the coronal slices. Observed differences between coronal and horizontal planes suggest anisotropy of the intracortical circuitry. In conclusion, ATN inputs are processed differently in coronal and horizontal planes of the GRS and then conveyed to other cortical areas. In both planes, GRS superficial layers play an important role in signal propagation, which suggests that superficial neuronal cascade is crucial in the integration of multiple information sources. NEW & NOTEWORTHY Superficial neurons in the rat granular retrosplenial cortex (GRS) show distinctive late-spiking (LS) firing property. However, little is known about spatiotemporal dynamics of signal transduction in the GRS. We demonstrated LS neuron network relaying thalamic inputs to deep layers and anisotropic distribution of inhibition between coronal and horizontal planes. Since deep layers of the GRS receive inputs from the subiculum, GRS circuits may work as an integrator of multiple sources such as sensory and memory information.
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Chinnadurai, Thangam, and Subbiah Arungalai Vendan. "Predicción de la tasa de eliminación de material y rugosidad de la superficie de mecanizado por electroerosión de alambre de níquel utilizando la metodología de superficie de respuesta." Revista de Metalurgia 52, no. 4 (December 19, 2016): 077. http://dx.doi.org/10.3989/revmetalm.077.
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Este estudio se centra en la investigación de los efectos de los parámetros del proceso, a saber, corriente máxima (Ip), duración del impulso (Ton), duración de desconexión del impulso (Toff), presión del agua (Wp), velocidad de alimentación del alambre (WF), tensión del alambre (Wt ), servo voltaje (Sv) y ajuste de avance del servo (SFS), velocidad de eliminación de material (MRR) y rugosidad de la superficie (SR), para la fabricación de alambre de níquel por descarga eléctrica (Wire-EDM) utilizando el método “Taguchi”. Se ha adoptado la metodología superficial de respuesta (RSM) con objeto de desarrollar relaciones matemáticas entre los parámetros del proceso de corte de alambre y las variables de salida de la junta de soldadura para determinar los parámetros de potencia de la soldadura que conducen a la calidad óptima deseada de corte del alambre. Además, usando gráficas superficiales de respuesta, los efectos de interacción de los parámetros del proceso en las respuestas son analizados y discutidos. El software estadístico “Mini-tab” se utiliza para establecer el diseño y obtener las ecuaciones de regresión. Los modelos matemáticos desarrollados son probados por el método de análisis de la varianza (ANOVA) para comprobar su aptitud e idoneidad. Por último, se hace una comparación entre los resultados medidos y calculados, que están en buen acuerdo. Esto indica que los modelos desarrollados pueden predecir las respuestas con exactitud y precisión dentro de los límites de los parámetros de corte usados.
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Izaguirre, V., and A. I. Zavaleta. "Canales de calcio voltajes dependientes." Ciencia e Investigación 1, no. 1 (June 15, 1998): 49–61. http://dx.doi.org/10.15381/ci.v1i1.4979.
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La vía más importante para la entrada de Ca2+ en las células excitables (Células musculares, neuronas y células de glándulas neuroendocrinas) son los canales de Ca2+ voltajes dependientes. Al abrirse, permiten el flujo selectivo de iones Ca2+ a través del poro del canal, iniciándose una variedad de procesos intracelulares entre los que se incluyen la contracción muscular, la secreción de neurotransmisores, la expresión génica, la modulación de la excitabilidad de la membrana, el crecimiento de neuritas, etc. De esta forma, los canales de Ca2+ constituyen el enlace fundamental entre las señales eléctricas de la superficie de la membrana y las respuestas bioquímicas intracelulares. Debido al papel que juegan en muchos procesos fisiológicos y fisiopatológicos, en este trabajo se revisan aspectos relacionados con la estructura, clasificación, biología molecular y las propiedades biofísicas y farmacológicas de los canales de calcio voltajes dependientes.
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Carreón Garcidueñas, Héctor Guillermo, Ariosto Medina Flores, Engelbert Huape Padilla, and Luis Béjar Gómez. "Efecto del aporte térmico en la resistencia a la corrosión de un recubrimiento de acero inoxidable martensítico depositado por soldadura." Superficies y Vacío 32 (December 10, 2019): 6–13. http://dx.doi.org/10.47566/2019_syv32_1-010006.
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En el proceso de colada continua, los rodillos se utilizan para la contención, soporte, conducción y transporte de la losa. Para extender substancialmente la vida útil de los rodillos, la superficie está cubierta con una capa resistente al desgaste llamada revestimiento duro el cual es aplicado por medio de soldadura de recargue, para mejorar las superficies que se encuentran sometidas a desgaste severo, oxidación o corrosión de los rodillos. El objetivo del presente trabajo es estudiar el efecto del aporte térmico por medio de técnicas electroquímicas de un acero inoxidable martensítico 414N aplicado como revestimiento duro en agua de mar sintética. El proceso de soldadura para la aplicación de los recargues fue por medio de soldadura de arco con electrodo tubular (FCAW) variando el voltaje del arco. Las técnicas electroquímicas fueron polarización potenciodinámica (PP) y espectroscopia de impedancia electroquímica (EIS). Los resultados indican que todos los recargues presentan una estructura martensítica de listón, donde 26 V presentó un 5.44% de ferrita, 28 V 5.33% y 30 V 5.0%, se puede observar que con un alto aporte térmico empleado se obtiene la menor cantidad de ferrita. De los resultados electroquímicos se puede observar, para 30 V se tiene el comportamiento más activo teniendo un Ecorr de -535 mV/ECS, siendo para 26 V y 28 V los valores más nobles (-380 mV/ECS y -425 mV/ECS) respectivamente. Para los 28 y 30 V se presentan potenciales de ruptura de la pasividad (313 mV/ECS y 132 mV/ECS) respectivamente.
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WANG, JIA-JUNG, SHING-HONG LIU, CHING-IUAN CHERN, and JUI-HSAING HSIEH. "DEVELOPMENT OF AN ARTERIAL APPLANATION TONOMETER FOR DETECTING ARTERIAL BLOOD PRESSURE AND VOLUME." Biomedical Engineering: Applications, Basis and Communications 16, no. 06 (December 25, 2004): 322–30. http://dx.doi.org/10.4015/s101623720400044x.
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Traditional arterial tonometry permits noninvasive and continuous recording of the arterial pressure waveform, by applanating a superficial artery supported by a bone. In the paper, we present an arterial tonometer to simultaneously register the blood pressure waveform and the arterial time-varying volume. The tonometer consisted mainly of a chamber filled with a conductive fluid, a flexible diphragm in touch with an artery, and a pressure sensor used to detect the underlying arterial pressure. In addition, four electrodes were in parallel diposed in the chamber, two of them were triggered with a constant-current source, and the voltage difference between the other two inner electrodes was assocated with the amount of change in the arterial volume. The pressure calibration curve performed with a mercury sphygmomanometer showed a fairly linear relationship (r = 0.998) between the tonometer's chamber pressure and the voltage output of the pressure-sensing circuit. The volume calibration was carried out with vessel-like cylinders of various diameters and a linear relationship (r = 0.884) of the change in vessel volume to the voltage output of the volume-sensing circuit was obtained. Clinical testing results revealed that the noninvasive blood pressure measurement with the tonometer was appreciably consistent with the invasive measurement with the catheter-tipped pressure transducer. In summary, the arterial applanation tonometer developed may be used to reliably determine the full arterial blood pressure waveform and the change in the arterial volume, and to make the wall compliance assessment of a superficial artery possible.
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Magistretti, Jacopo, and Marco de Curtis. "Low-Voltage Activated T-Type Calcium Currents Are Differently Expressed in Superficial and Deep Layers of Guinea PigPiriform Cortex." Journal of Neurophysiology 79, no. 2 (February 1, 1998): 808–16. http://dx.doi.org/10.1152/jn.1998.79.2.808.
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Magistretti, Jacopo and Marco de Curtis. Low-voltage activated T-type calcium currents are differently expressed in superficial and deep layers of guinea pig piriform cortex. J. Neurophysiol. 79: 808–816, 1998. A variety of voltage-dependent calcium conductances are known to control neuronal excitability by boosting peripheral synaptic potentials and by shaping neuronal firing patterns. The existence and functional significance of a differential expression of low- and high-voltage activated (LVA and HVA, respectively) calcium currents in subpopulations of neurons, acutely isolated from different layers of the guinea pig piriform cortex, were investigated with the whole cell variant of the patch-clamp technique. Calcium currents were recorded from pyramidal and multipolar neurons dissociated from layers II, III, and IV. Average membrane capacitance was larger in layer IV cells [13.1 ± 6.2 (SD) pF] than in neurons from layers II and III (8.6 ± 2.8 and 7.9 ± 3.1 pF, respectively). Neurons from all layers showed HVA calcium currents with an activation voltage range positive to −40 mV. Neurons dissociated from layers III and IV showed an LVA calcium current with the biophysical properties of a T-type conductance. Such a current displayed the following characteristics: 1) showed maximal amplitude of 11–16 pA/pF at −30 mV, 2) inactivated rapidly with a time constant of ∼22 ms at −30 mV, and 3) was completely steady-state inactivated at −60 mV. Only a subpopulation of layer II neurons (group 2 cells; circa 18%) displayed an LVA calcium current similar to that observed in deep layers. The general properties of layer II-group 2 cells were otherwise identical to those of group 1 neurons. The present study demonstrates that LVA calcium currents are differentially expressed in neurons acutely dissociated from distinct layers of the guinea pig piriform cortex.
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Zhong, Li, and Xi Han. "Influence of Hydrogen on the Plasmas Nitriding Process of 35CrMo Steel." Advanced Materials Research 295-297 (July 2011): 1004–9. http://dx.doi.org/10.4028/www.scientific.net/amr.295-297.1004.
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The mechanism of the formation of active nitrogen atoms and the function of hydrogen molecules for the dissociation of the mixture of nitrogen and hydrogen in the plasma nitriding process are discussed in this paper. The results show that the nitrided case thickness of nitrided samples become thinner and the surface hardness decreases with the increase of cathode voltage. Active nitrogen atoms mainly result from non-elastic collision between positive ions H2+ and neutral particles N2 for N2-H2 mixture plasma nitriding at 550V cathode voltage, the volume percent of e-Fe3N and the superficial nitrogen concentration of plasma nitrided case decrease with the increase of the mixture ratio of N2/H2. However, active nitrogen atoms mainly result from non-elastic collision between energetic positive ions H2+, N2+and neutral particles N2 for N2-H2 mixture plasma nitriding at 650V cathode voltage. The existence of a few of nitrogen molecules makes critical energy of positive ions H2+ dissociating neutral N2 molecules drop to 26.06eV and the cathode voltage threshold value become 490V.
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Kalinowski, Douglas P., Laura E. Edsberg, Robert A. Hewson, Robert H. Johnson, and Michael S. Brogan. "Low-Voltage Direct Current as a Fungicidal Agent for Treating Onychomycosis." Journal of the American Podiatric Medical Association 94, no. 6 (November 1, 2004): 565–72. http://dx.doi.org/10.7547/0940565.
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Onychomycosis, most commonly caused by two species of dermatophyte fungi—Trichophyton rubrum and Trichophyton mentagrophytes—is primarily treated with regimens of topical and systemic antifungal medications. This study was undertaken to evaluate in vitro the efficacy of low-voltage direct current as an antifungal agent for treating onychomycosis. Agar plate cultures of T rubrum and T mentagrophytes were subjected to low-voltage direct current electrostimulation, and antifungal effects were observed as zones in the agar around the electrodes lacking fungal growth. Zones devoid of fungal growth were observed for T rubrum and T mentagrophytes around anodes and cathodes in a dose-dependent manner in the current range of 500 μA to 3 mA. Low-voltage direct current electrostimulation has great clinical potential for the treatment of onychomycosis and perhaps other superficial maladies of fungal etiology. (J Am Podiatr Med Assoc 94(6): 565–572, 2004)
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Work, J., J. H. Galla, B. B. Booker, J. A. Schafer, and R. G. Luke. "Effect of ADH on chloride reabsorption in the loop of Henle of the Brattleboro rat." American Journal of Physiology-Renal Physiology 249, no. 5 (November 1, 1985): F698—F703. http://dx.doi.org/10.1152/ajprenal.1985.249.5.f698.
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Both in vivo superficial loop segment microperfusion and in vitro perfusion of isolated medullary thick ascending limb segments were used to assess the effect of vasopressin on loop of Henle chloride absorption in the Brattleboro rat. Superficial loop segments were perfused between the latest proximal and earliest distal tubule in vivo at 19.2 +/- 0.4 nl/min (mean +/- SE) with an artificial tubule fluid. Under control conditions, absolute chloride reabsorption was 1,596 +/- 61 pmol/min and increased to 1,876 +/- 102 after intravenous infusion of vasopressin (P less than 0.005). Distal tubule fluid chloride concentration decreased 4.6 +/- 1.5 meq/liter (P less than 0.05), and fractional chloride reabsorption increased 4.8 +/- 2.0% (P less than 0.05). For in vitro perfusion, medullary thick ascending limb segments were bathed and perfused (9-15 nl/min) with phosphate-buffered solutions at 38 degrees C. Under control conditions, transepithelial voltage was +2.4 +/- 0.3 mV, lumen positive, and the net chloride flux was 147 +/- 24 pmol X min-1 X mm-1 in the absorptive direction. Addition of vasopressin to the bathing solution increased net chloride reabsorption to 342 +/- 56 pmol X min-1 X mm-1 (P less than 0.02) and transepithelial voltage to 3.0 +/- 0.3 mV (P less than 0.002). An additional group of tubules was examined under identical conditions; however, vasopressin was removed from the bathing medium during a subsequent recovery period. In these experiments, net chloride flux and transepithelial voltage significantly increased compared with the control period and returned to control values upon removal of vasopressin from the bath.(ABSTRACT TRUNCATED AT 250 WORDS)
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Hyder, AHM Golam, Brian A. Morales, Malynda A. Cappelle, Stephen J. Percival, Leo J. Small, Erik D. Spoerke, Susan B. Rempe, and W. Shane Walker. "Evaluation of Electrodialysis Desalination Performance of Novel Bioinspired and Conventional Ion Exchange Membranes with Sodium Chloride Feed Solutions." Membranes 11, no. 3 (March 19, 2021): 217. http://dx.doi.org/10.3390/membranes11030217.
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Electrodialysis (ED) desalination performance of different conventional and laboratory-scale ion exchange membranes (IEMs) has been evaluated by many researchers, but most of these studies used their own sets of experimental parameters such as feed solution compositions and concentrations, superficial velocities of the process streams (diluate, concentrate, and electrode rinse), applied electrical voltages, and types of IEMs. Thus, direct comparison of ED desalination performance of different IEMs is virtually impossible. While the use of different conventional IEMs in ED has been reported, the use of bioinspired ion exchange membrane has not been reported yet. The goal of this study was to evaluate the ED desalination performance differences between novel laboratory‑scale bioinspired IEM and conventional IEMs by determining (i) limiting current density, (ii) current density, (iii) current efficiency, (iv) salinity reduction in diluate stream, (v) normalized specific energy consumption, and (vi) water flux by osmosis as a function of (a) initial concentration of NaCl feed solution (diluate and concentrate streams), (b) superficial velocity of feed solution, and (c) applied stack voltage per cell-pair of membranes. A laboratory‑scale single stage batch-recycle electrodialysis experimental apparatus was assembled with five cell‑pairs of IEMs with an active cross-sectional area of 7.84 cm2. In this study, seven combinations of IEMs (commercial and laboratory-made) were compared: (i) Neosepta AMX/CMX, (ii) PCA PCSA/PCSK, (iii) Fujifilm Type 1 AEM/CEM, (iv) SUEZ AR204SZRA/CR67HMR, (v) Ralex AMH-PES/CMH-PES, (vi) Neosepta AMX/Bare Polycarbonate membrane (Polycarb), and (vii) Neosepta AMX/Sandia novel bioinspired cation exchange membrane (SandiaCEM). ED desalination performance with the Sandia novel bioinspired cation exchange membrane (SandiaCEM) was found to be competitive with commercial Neosepta CMX cation exchange membrane.
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Li, Zhan Kai, Jing Qin Wang, Fu Min Zhang, Xin Xia, Hao Hua Li, Long Meng, Peng Zhang, and Li Bin Qi. "Research of Electric Properties of Monocrystalline Silicon Solar Battery." Advanced Materials Research 427 (January 2012): 128–32. http://dx.doi.org/10.4028/www.scientific.net/amr.427.128.
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With crystalline silicon solar battery industry is developing rapidly, there are scientific significance and application value for guiding the industrial production using analysis of the electrical properties of crystalline silicon solar battery. This paper studies that the main parameters of monocrystalline crystal silicon solar battery: the junction depth and superficial concentrations influence on electrical characteristics of monocrystalline silicon solar battery. The result shows that for maximum efficiency, it is bound to get the largest possible open circuit voltage, short circuit current and fill factor of the product, therefore, it is necessary to control the junction depth and doping parameters. If the junction depth is constant, with the increased superficial doping concentration of monocrystalline silicon solar battery, the photoelectric conversion efficiency of the battery increases slowly at first and then rapidly decreases, and the deeper the junction depth is, the more obvious trend of the photoelectric conversion efficiency is. If the superficial doping concentration is constant, the photoelectric conversion efficiency of the battery is increased with the reductive junction depth of surface of monocrystalline silicon solar battery.
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Behjat, Vahid, Afshin Rezaei-Zare, Issouf Fofana, and Ali Naderian. "Concept Design of a High-Voltage Electrostatic Sanitizer to Prevent Spread of COVID-19 Coronavirus." Energies 14, no. 22 (November 22, 2021): 7808. http://dx.doi.org/10.3390/en14227808.
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In addition to public health measures, including social distancing, masking, cleaning, surface disinfection, etc., ventilation and air filtration can be a key component of a multi-pronged risk mitigation strategy against COVID-19 transmission indoors. Electrostatic precipitators (ESP) have already proved their high performance in fluid filtration, particularly in industrial applications, to control exhaust gas emissions and remove fine and superfine particles from the flowing gas, using high-voltage electrostatic fields and forces. In this contribution, a high-voltage electrostatic sanitizer (ESS), based on the electrostatic precipitation concept, is proposed as a supportive measure to reduce indoor air infection and prevent the spread of COVID-19 coronavirus. The finite element method (FEM) is used to model and simulate the proposed ESS, taking into account three main mechanisms involving in electrostatic sanitization, namely electrostatic field, airflow, and aerosol charging and tracing, which are mutually coupled to each other and occur simultaneously during the sanitization process. To consider the capability of the designed ESS in capturing superfine particles, functional parameters of the developed ESS, such as air velocity, electric potential, and space charge density, inside the ESS are investigated using the developed FEM model. Simulation results demonstrate the ability of the designed ESS in capturing aerosols containing coronavirus, precipitating suspended viral particles, and trapping them in oppositely charged electrode plates.
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Muñoz Aguirre, N., J. Eduardo Rivera-López, L. Martínez Pérez, and Pedro A. Tamayo Meza. "Synthesis and Atomic Force Microscopy Contact Current Images of Aluminum Doped ZnO Thin Films." Materials Science Forum 644 (March 2010): 109–12. http://dx.doi.org/10.4028/www.scientific.net/msf.644.109.
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Aluminum doped ZnO thin films were synthesized by the water-mist assisted spray pyrolysis technique. The structural characterization by means of X-Ray diffraction measurements is reported. By means of Atomic Force Microscopy, the superficial electrical characteristics of the thin films are studied. Specifically, contact current images are shown and discussed. It is important to emphasize that in spite of no voltage is applied to the Atomic Force Microscopy contact conductive tip, current images are getting.
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Furutani, Kenta, Miho Ikoma, Hideaki Ishii, Hiroshi Baba, and Tatsuro Kohno. "Bupivacaine Inhibits Glutamatergic Transmission in Spinal Dorsal Horn Neurons." Anesthesiology 112, no. 1 (January 1, 2010): 138–43. http://dx.doi.org/10.1097/01.anes.0000365964.97138.9a.
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Background The local anesthetic bupivacaine is thought not only to block sodium channels but also to interact with various receptors. Here, the authors focus on excitatory glutamatergic transmission in the superficial dorsal horn of the spinal cord with respect to its importance for nociceptive processing. Methods The effects of bupivacaine on the response to exogenous administration of N-methyl-D-aspartate (NMDA) receptor agonists were examined in lamina II neurons of adult rat spinal cord slices using the whole-cell patch-clamp technique. Results Bupivacaine (0.5, 2 mm) dose-dependently reduced the peak amplitudes of exogenous NMDA-induced currents. However, this inhibitory effect of bupivacaine (2 mm) was not blocked by the presence of tetrodotoxin, a sodium channel blocker, or La(3+), a voltage-gated Ca+ channel blocker, and was unaffected by changes in pH conditions. Moreover, intrapipette guanosine-5'-O-(2-thiodiphosphate) (1 mm), a G-protein inhibitor, did not block the reduction of NMDA current amplitudes by bupivacaine. Similarly, lidocaine, ropivacaine, and mepivacaine also reduced the amplitudes of NMDA-induced currents. Conclusions These findings raise the possibility that the antinociceptive effect of bupivacaine may be due to direct modulation of NMDA receptors in the superficial dorsal horn. In addition to voltage-gated sodium channels, glutamate NMDA receptors are also important for analgesia induced by local anesthetics.
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Costa, Vladimir Santos da, and Afonso De Moraes Paiva. "THE IMPACT OF SURFACE HEAT FLUXES ON THE SIMULATION OF THE BRAZIL CURRENT." Revista Brasileira de Geofísica 31, no. 2 (June 1, 2013): 307. http://dx.doi.org/10.22564/rbgf.v31i2.296.
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ABSTRACT. The impact of different formulations of surface heat fluxes (no fluxes, climatological fluxes, restoring of SST towards climatology, climatological fluxes plus SST restoring, and model-computed fluxes via bulk formulas) on the modeling of the Brazil Current is investigated in numerical simulations performed with the Regional Ocean Model (ROMS). While mechanical forcing may be dominant, it is shown that correct upper ocean currents and thermal structure can only be obtained when heat fluxes are implemented, even in regions of strong horizontal advection, and that some form of feedback of the ocean state upon the fluxes is also a necessary condition. This results are of particular importance for ocean modeling developed having operational oceanography in view. Keywords: Brazil Current, surface heat flux, numerical modeling. RESUMO. O impacto de diferentes formulações dos fluxos de calor em superfície (sem fluxos, fluxos climatológicos, relaxamento de TSM para climatologia, fluxos climatológicos mais relaxamento de TSM e fluxos calculados pelo modelo com “bulk formulas”) sobre a modelagem da Corrente do Brasil é investigado em simulações numéricas com o Regional Ocean Model (ROMS). Apesar da forçante mecânica ser dominante, mostra-se que uma correta representação de correntes e da estrutura térmica nas camadas superiores do oceano somente são possíveis quando fluxos de calor são implementados e que algum tipo de retroalimentação da TSM sobre os fluxos é também necessária. Estes resultados são particularmente importantes na modelagem voltada para a oceanografia operacional. Palavras-chave: Corrente do Brasil, fluxos superficial de calor, modelagem numérica.
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Carvalho, Nathalia Alborghetti, and Evelise Ruthschilling. "Inovação em metodologia de projeto aplicada ao design de superfície voltado para moda." ModaPalavra 9, no. 17 (January 8, 2016): 179–94. http://dx.doi.org/10.5965/1982615x09172016179.
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Schnoebel, Rose, Matthias Wolff, Saskia C. Peters, Michael E. Bräu, Andreas Scholz, Gunter Hempelmann, Horst Olschewski, and Andrea Olschewski. "Ketamine impairs excitability in superficial dorsal horn neurones by blocking sodium and voltage-gated potassium currents." British Journal of Pharmacology 146, no. 6 (November 2005): 826–33. http://dx.doi.org/10.1038/sj.bjp.0706385.
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Cherny, Vladimir V., and Thomas E. DeCoursey. "Ph-Dependent Inhibition of Voltage-Gated H+ Currents in Rat Alveolar Epithelial Cells by Zn2+ and Other Divalent Cations." Journal of General Physiology 114, no. 6 (November 29, 1999): 819–38. http://dx.doi.org/10.1085/jgp.114.6.819.
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Inhibition by polyvalent cations is a defining characteristic of voltage-gated proton channels. The mechanism of this inhibition was studied in rat alveolar epithelial cells using tight-seal voltage clamp techniques. Metal concentrations were corrected for measured binding to buffers. Externally applied ZnCl2 reduced the H+ current, shifted the voltage-activation curve toward positive potentials, and slowed the turn-on of H+ current upon depolarization more than could be accounted for by a simple voltage shift, with minimal effects on the closing rate. The effects of Zn2+ were inconsistent with classical voltage-dependent block in which Zn2+ binds within the membrane voltage field. Instead, Zn2+ binds to superficial sites on the channel and modulates gating. The effects of extracellular Zn2+ were strongly pHo dependent but were insensitive to pHi, suggesting that protons and Zn2+ compete for external sites on H+ channels. The apparent potency of Zn2+ in slowing activation was ∼10× greater at pHo 7 than at pHo 6, and ∼100× greater at pHo 6 than at pHo 5. The pHo dependence suggests that Zn2+, not ZnOH+, is the active species. Evidently, the Zn2+ receptor is formed by multiple groups, protonation of any of which inhibits Zn2+ binding. The external receptor bound H+ and Zn2+ with pKa 6.2–6.6 and pKM 6.5, as described by several models. Zn2+ effects on the proton chord conductance–voltage (gH–V) relationship indicated higher affinities, pKa 7 and pKM 8. CdCl2 had similar effects as ZnCl2 and competed with H+, but had lower affinity. Zn2+ applied internally via the pipette solution or to inside-out patches had comparatively small effects, but at high concentrations reduced H+ currents and slowed channel closing. Thus, external and internal zinc-binding sites are different. The external Zn2+ receptor may be the same modulatory protonation site(s) at which pHo regulates H+ channel gating.
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Nascimento, Walnice Maria Oliveira, Maria Socorro Padilha Oliveira, José Edmar Urano Carvalho, and Carlos Hans Müller. "Influência da posição de semeadura na germinação, vigor e crescimento de plântulas de bacabinha (Oenocarpus mapora Karsten - Aecaceae)." Revista Brasileira de Sementes 24, no. 1 (2002): 179–82. http://dx.doi.org/10.1590/s0101-31222002000100026.
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A bacabinha (Oenocarpus mapora Karsten) é uma espécie de palmeira que cresce em touceiras de cinco a 12 indivíduos, nativa da Amazônia, podendo ainda ser encontrada em alguns países do norte da América do Sul e da América Central. Seu fruto é utilizado para fabricar refresco, sorvetes e cremes. Extraindo também, de seu estipe palmito, com excelentes características organolépticas e bom rendimento, devido a suas potencialidades essa espécie vem sendo estudada no sentido de domesticá-la. Com o objetivo de verificar o efeito da posição de semeadura na germinação, no vigor e no crescimento das plântulas, foi realizado o experimento, testando-se quatro posições de semeadura com três repetições em parcelas de 25 sementes, sendo instalado em delineamento inteiramente casualizado. Avaliou-se a percentagem, o tempo médio de germinação e o comprimento das plântulas. Os resultados indicaram que a germinação de sementes de bacabinha não foi afetada pela posição de semeadura, alcançando valores acima de 92%, porém, quando as sementes foram postas para germinar com o poro germinativo voltado para a superfície e com a rafe na posição horizontal e voltada para cima, as sementes germinaram em menor tempo. O desenvolvimento inicial das plântulas de bacabinha foi afetado pela posição de semeadura.
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Hao, Ming Feng, Yong Liu, Xue Tao He, Yu Mei Ding, and Wei Min Yang. "Factors Influencing Diameter of Polypropylene Fiber in Melt Electrospinning." Advanced Materials Research 221 (March 2011): 129–34. http://dx.doi.org/10.4028/www.scientific.net/amr.221.129.
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Melt electrospinning is a safer, more environmentally friendly and cheaper alternative to solution electrospinning in producing superfine fibers. In this paper, a novel melt electrospinning device was used, which has higher efficiency than conventional equipment. Polypropylene is widely used in many fields and it is difficult to find a suitable solvent for its solution electrospinning at room temperature, so it was chosen in this study. The influences of the electrospinning parameters such as temperature and voltage on the diameter of the spinning fibers have been studied. Temperatures higher than normal processing temperatures were used in present electrospinning system in order to reduce the viscosity of the polymer melt sufficiently. Good quality fibers with smooth surfaces and with diameters mostly smaller than 10 microns were spun successfully. It was found that there was an optimum point for the spinning voltage (70-80KV) and the temperature (230-260°C) to get fine fibers.
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Chen, Wen Jie, Bin Jie Xin, and Xiang Ji Wu. "Study on the Preparation of PSA NanoFibers Using Electro-Spinning Technology and its Characterizations." Key Engineering Materials 531-532 (December 2012): 527–30. http://dx.doi.org/10.4028/www.scientific.net/kem.531-532.527.
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Polysulfonamide (PSA) superfine fibers were prepared by the self-developed device using the electrospinning technology. The micro surface morphology of the manufactured PSA fibers was characterized by the Scanning Electron Microscope (SEM). It was found that the diameter of PSA fibers and its variance can be influenced by the electrospinning parameters. The experimental results indicate that the morphology of PSA fibers ranged from irregular (beaded) to uniform structure with an increase of solution concentration; the thickness and its variance of the PSA fibers were decreased with the increasing of applied voltage; the morphology and thickness of the PSA fibers were also affected by the tip-to-collector distance. Our investigation shows that the diameter of the PSA fibers can reach around 100nm when spun at the conditions of 28kv applied voltage, 10wt% solution concentration and 15 cm tip-target distance, with a related homogeneous network distribution.
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Li, Hao Hua, You Hua Wang, and Dun Yu Zhu. "Research of a New Type of Solar Cell Materials." Applied Mechanics and Materials 488-489 (January 2014): 44–47. http://dx.doi.org/10.4028/www.scientific.net/amm.488-489.44.
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Solar energy is the inexhaustible,enewable Energy. The solar cell is the solar light energy into electricity. The unique advantages of solar cell. Potential, more than wind, hydro, geothermal energy, nuclear energy and other resources, is expected to become the main pillar of power supply in the future. This paper studies that the main parameters of monocrystalline crystal silicon solar battery: the junction depth and superficial concentrations influence on electrical characteristics of monocrystalline silicon solar battery. The result shows that for maximum efficiency, it is bound to get the largest possible open circuit voltage, short circuit current and fill factor of the product, therefore, it is necessary to control these two parameters, the junction depth and doping parameters. If the junction depth is constant, with the increased superficial doping concentration of monocrystalline silicon solar battery, the photoelectric conversion efficiency of the battery increases slowly at first and then rapidly decreases, and the deeper the junction depth is, the more obvious trend of the photoelectric conversion efficiency is.
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Virca, Ioan. "Statistical Analysis of Results Obtained in the Hardening Surface of the Metal Powder Materials with Optical Radiation Impulses." Scientific Bulletin 20, no. 2 (December 1, 2015): 79–85. http://dx.doi.org/10.1515/bsaft-2015-0012.
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Abstract The paper presents how is processed the data resulted from application of pulsed optical superficial treatments on surfaces of materials made of metal powders. The parameters of the electrotechnological regime work are variable in the experimental program, namely the distance between the axis focal energy sources and surfaces play, the number of energy pulses applied to the voltage pulse of optical radiation, which causes a statistical analysis more complex, after which it will precise drawing lessons that will lead to a calculation microhardness model in the superificial layer of material.
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Dulce-Moreno, Hector Jaime, Valeri Dougar-Jabon, and Piotr Andrei-Tsygankov. "Implantación iónica." Respuestas 8, no. 1 (June 18, 2016): 19–30. http://dx.doi.org/10.22463/0122820x.707.
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En este trabajo se presenta una revisión de las diferentes técnicas de implantación de iones desde los implantadores por haces iónicos, utilizados en la fabricación de semiconductores, pasando por una serie de desarrollos con base en la tecnología de la física del plasma, hasta llegar a la técnica denominada Implantación Iónica Tridimensional (3DII). Para cada una de las técnicas de implantación iónica se presentan los dispositivos más comunes y se analizan sus características principales. Para el caso de la Implantación Iónica Tridimensional se describe el equipo JUPITER (Joint Universal Plasma and Ion Technologies Experimental Reactor), único en el mundo, para la investigación de descargas pulsadas de alto voltaje a bajas presiones y para el tratamiento superficial de materiales. Este dispositivo se implementó en el Laboratorio de Física del Plasma y Corrosión de la Universidad Industrial de Santander, con la colaboración financiera de COLCIENCIAS y con la cooperación de la Universidad Técnica Estatal Bauman de Moscú.Palabras Clave: Implantación iónica tridimensional; descarga de alto voltaje; nitruración.
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Sanchez, J. A., J. A. Dani, D. Siemen, and B. Hille. "Slow permeation of organic cations in acetylcholine receptor channels." Journal of General Physiology 87, no. 6 (June 1, 1986): 985–1001. http://dx.doi.org/10.1085/jgp.87.6.985.
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Block, permeation, and agonist action of small organic amine compounds were studied in acetylcholine receptor (AChR) channels. Single channel conductances were calculated from fluctuation analysis at the frog neuromuscular junction and measured by patch clamp of cultured rat myotubes. The conductance was depressed by a few millimolar external dimethylammonium, arginine, dimethyldiethanolammonium, and Tris. Except with dimethylammonium, the block was intensified with hyperpolarization. A two-barrier Eyring model describes the slowed permeation and voltage dependence well for the three less permeant test cations. The cations were assumed to pause at a site halfway across the electric field of the channel while passing through it. For the voltage-independent action of highly permeant dimethylammonium, a more appropriate model might be a superficial binding site that did not prevent the flow of other ions, but depressed it. Solutions of several amine compounds were found to have agonist activity at millimolar concentrations, inducing brief openings of AChR channels on rat myotubes in the absence of ACh.
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Stępińska, Izabela, Elżbieta Czerwosz, Mirosław Kozłowski, Halina Wronka, and Piotr Dłużewski. "Studies of field emission process influence on changes in CNT films with different CNT superficial density." Materials Science-Poland 36, no. 1 (May 18, 2018): 27–33. http://dx.doi.org/10.1515/msp-2018-0001.
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Abstract Field emission from materials at high electric fields can be associated with unfavorable or even destructive effect on the surface of the investigated cathode. The impact of high voltage electric power supply causes locally very strong electric fields focusing on the cathode surface. It causes a number of phenomena, which can adversely affect the morphology and the structure of the cathode material. Such a phenomenon is, for example, peeling of an emissive layer from the substrate or its burnout. It results in tearing of the layer and a decrease or loss of its ability to electrons emission. The cold cathodes in a form of CNT films with various CNTs superficial distribution are obtained by physical vapor deposition followed by chemical vapor deposition. CNTs are catalyzed in pyrolytic process with xylene (CVD), by Ni in a form of nanograins (few nm in size) placed in carbonaceous matrix. These films are built of emissive CNTs - carbonaceous film deposited on different substrates. In this work, the morphology and topography of superficial changes resulting from external electric field in such films were investigated.
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Edelstein, Jerome, Walter Peters, and Robert Cartotto. "Lightning Injury: A Review and Case Presentations." Canadian Journal of Plastic Surgery 2, no. 4 (December 1994): 164–68. http://dx.doi.org/10.1177/229255039400200407.
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J Edelstein, W Peters, R Cartotto. Lightning injury: A review and case presentations. Can J Plast Surg 1994;2(4):164-168. Lightning injuries are relatively uncommon, although thousands are affected each year. Many patients are left with permanent sequelae. This type of injury is very different from other high voltage electrical injuries. Lightning burns are usually superficial and only about one quarter of those struck by lightning will actually die. The number of deaths can be reduced if proper early resuscitative methods are used. Two lightning-strike victims are presented. The first patient suffered transient neurological abnormalities, eye and ear injuries including permanent sensorineural hearing loss, and superficial burns over 70% of his body surface area. The second patient, who wore bilateral arm prostheses, was struck by lightning while driving his motor boat. The lightning welded one of his prostheses to the steering wheel of the boat. He sustained a 10% partial thickness burn, but had no permanent sequelae. A review of the current literature is presented, including the pathophysiology, multisystem clinical features and treatment of lightning injury.
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Hernández-Almudi, P., D. Suárez, E. Montijano, and J. Merino. "Control inteligente mediante escalado dinámico voltaje-frecuencia (DVFS) de la temperatura en procesadores embebidos." Revista Iberoamericana de Automática e Informática industrial 18, no. 4 (September 30, 2021): 396. http://dx.doi.org/10.4995/riai.2021.14200.
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<p>El aumento de la capacidad de cálculo de los procesadores embebidos ha generado una revolución en numerosos dominios de aplicación como la computación móvil o la robótica. La disipación del consumo producido por estos cálculos en una superficie tan pequeña hace que la disipación de energía suponga un problema de primer orden. Por un lado, no es posible aplicar técnicas de disipación activas y, por otro, las exigencias de diseño impiden una correcta disipación pasiva. Para resolver este problema, este trabajo presenta una metodología de control para el mantenimiento de una temperatura bajo control mediante el uso de escalado dinámico de la frecuencia del procesador (DVFS, Dynamic Voltage Frequency Scaling). La solución incluye un esquema de control de temperatura basado en realimentación junto con un supervisor que ajusta los parámetros del controlador en base al tipo de carga del trabajo. La estrategia de control propuesta se ha implementado tanto en espacio de usuario como driver dentro del kernel de Linux. Los experimentos realizados en una plataforma real demuestran que, comparado con el control existente en la actualidad, nuestra propuesta es capaz de gestionar la temperatura del procesador con más precisión, manteniendo niveles similares de eficiencia en la ejecución de benchmarks conocidos.</p>
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Glasgow, Stephen D., and C. Andrew Chapman. "Local Generation of Theta-Frequency EEG Activity in the Parasubiculum." Journal of Neurophysiology 97, no. 6 (June 2007): 3868–79. http://dx.doi.org/10.1152/jn.01306.2006.
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The parasubiculum is a major component of the hippocampal formation that receives inputs from the CA1 region, anterior thalamus, and medial septum and that projects primarily to layer II of the entorhinal cortex. Hippocampal theta-frequency (4–12 Hz) electroencephalographic (EEG) activity has been correlated with sensorimotor integration, spatial navigation, and memory functions. The present study was aimed at determining if theta is also generated locally within the parasubiculum versus volume conducted from adjacent structures. In urethan-anesthetized rats, the phase-reversal of theta activity between superficial and deep layers of the parasubiculum was demonstrated using differential recordings from movable bipolar electrodes that eliminate the influence of volume-conducted activity. Parasubicular theta was abolished by atropine, and was in phase with theta in stratum radiatum/lacunosum-moleculare of the CA1 region. Whole cell current-clamp recordings in brain slices were then used to determine if parasubicular theta may be generated in part by membrane potential oscillations in layer II neurons. Membrane potential oscillations occurred in most layer II neurons, including four putative interneurons, when cells were held at near-threshold voltages using current injection. The frequency of oscillations increased from 3.2 to 6.1 Hz when bath temperature was raised from 22 to 32°C, and oscillations persisted in the presence of blockers of fast ionotropic glutamatergic and GABAergic synaptic transmission. Oscillations are therefore likely generated by intrinsic, voltage-dependent ionic conductances. These results indicate that theta field activity is generated locally within the parasubiculum and that intrinsic membrane potential oscillations, synchronized by local inhibitory inputs, may contribute to the generation of this activity.
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Figueroa Godoy, Fernando, Jacinto Torres Jimenez, Rubén Jaramillo Vacio, Javier Yáñez Mendiola, and José Ángel Colin. "Analysis of Insulating Material of XLPE Cables considering Innovative Patterns of Partial Discharges." Mathematical Problems in Engineering 2017 (2017): 1–10. http://dx.doi.org/10.1155/2017/2379418.
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This paper aims to analyze the quality of insulation in high voltage underground cables XLPE using a prototype which classifies the following usual types of patterns of partial discharge (PD): (1) internal PD, (2) superficial PD, (3) corona discharge in air, and (4) corona discharge in oil, in addition to considering two new PD patterns: (1) false contact and (2) floating ground. The tests and measurements to obtain the patterns and study cases of partial discharges were performed at the Testing Laboratory Equipment and Materials (LEPEM) of the Federal Electricity Commission of Mexico (CFE) using a measuring equipment LDIC and norm IEC60270. To classify the six patterns of partial discharges mentioned above a Probabilistic Neural Network Bayesian Modified (PNNBM) method having the feature of using a large amount of data will be used and it is not saturated. In addition, PNN converges, always finding a solution in a short period of time with low computational cost. The insulation of two high voltage cables with different characteristics was analyzed. The test results allow us to conclude which wire has better insulation.
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Tassi, Rutinéia, Daniel Gustavo Allasia Piccilli, Santiago Chaves Brancher, and Carlos Augusto Roman. "Preferências da população de diferentes estratos sociais no manejo das águas pluviais urbanas." Ambiente Construído 16, no. 3 (September 2016): 39–52. http://dx.doi.org/10.1590/s1678-86212016000300091.
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Resumo Muitos municípios brasileiros possuem legislação específica voltada para o manejo das águas pluviais no meio urbano, tendo como principal objetivo a redução do escoamento superficial. Entre as medidas promovidas se encontra a obrigatoriedade de implantação de diferentes dispositivos nos lotes que funcionem armazenando ou infiltrando o excesso do escoamento superficial causado pela urbanização, de forma a compensar o impacto desta. Esse tipo de prática é conhecido como técnica compensatória (TC). Diante das diferentes TC que podem ser escolhidas, neste artigo são apresentadas as preferências e principais percepções da população de três diferentes estratos socioeconômicos a respeito das TCs. O estudo foi conduzido na cidade de Santa Maria, RS, que como outros municípios brasileiros de médio porte, ainda deverá adotar algum tipo de política pública voltada para a gestão das águas pluviais no meio urbano. Foram entrevistadas 518 residências em bairros representativos da baixa classe alta, alta classe média e baixa classe média, que possuem a mesma diretriz para ocupação do solo. Os resultados revelaram importantes aspectos a respeito do entendimento dos entrevistados no que se refere ao manejo das águas pluviais em meio urbano e evidenciaram que a preferência por TC de armazenamento ou infiltração pode ser influenciada pela classe socioeconômica. Ainda, a entrevista permitiu identificar que em mais de 90% dos domicílios entrevistados já existe conhecimento sobre esse tipo de política pública.
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Yang, Lie, Larry S. Benardo, Helen Valsamis, and Douglas S. F. Ling. "Acute Injury to Superficial Cortex Leads to a Decrease in Synaptic Inhibition and Increase in Excitation in Neocortical Layer V Pyramidal Cells." Journal of Neurophysiology 97, no. 1 (January 2007): 178–87. http://dx.doi.org/10.1152/jn.01374.2005.
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Injury to the superficial layers of cerebral cortex produces alterations in the synaptic responses of local circuits that promote the development of seizures. To further delineate the specific changes in synaptic strength that are induced by this type of cortical injury, whole cell voltage-clamp recordings were used to examine evoked and spontaneous synaptic events from layer V pyramidal cells in coronal slices prepared from surgically traumatized rat neocortices in which the superficial third of the cortex (layers I, II, and part of III) was removed. Slices from intact neocortices were used as controls. Examinations of fast inhibitory postsynaptic currents (IPSCs) indicated that traumatized slices were disinhibited, exhibiting evoked IPSCs (eIPSCs) with lower peak amplitudes. Measurements of spontaneous IPSCs (sIPSCs) revealed no difference in the mean amplitudes of sIPSCs recorded in traumatized versus control slices. However, the mean sIPSC frequency was lower in traumatized slices, indicative of a decrease in GABA release at these inhibitory synapses. Traumatized slices also displayed an increase in synaptic excitation, exhibiting spontaneous EPSCs (sESPCs) with larger peak amplitudes and higher frequencies. Peak-scaled nonstationary fluctuation analysis of sEPSCs and sIPSCs was used to obtain estimates of the unit conductance and number of functional receptor channels. EPSC and IPSC channel numbers and IPSC unit conductance did not differ between traumatized and intact slices. However, the mean unit conductance of EPSCs was higher (+25%) in traumatized slices. These findings suggest that acute injury to the superficial neocortical layers results in a disinhibition of cortical circuits that stems from a decline in GABA release likely due to the loss of superficial inhibitory interneurons and an enhancement of synaptic excitation consequent to an increase in the AMPA receptor unit conductance.
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Li, Quan Lu, Jing Wu, Yin Hong Zhang, Ran Liao, Hai Xia Cheng, and Qing Qing Yang. "The Effects of Superfine Powder and Sintering Technique upon Properties and Applications of some Piezoelectric Ceramics." Advanced Materials Research 749 (August 2013): 3–12. http://dx.doi.org/10.4028/www.scientific.net/amr.749.3.
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This paper briefly reports on the improved properties and bettered applications of some piezoelectric ceramics (i. e. S-PZT, etc.) of ferro/piezoelectric community by means of bettering their technological process links, especial superfine grinding of powder of raw materials, and sintering technique of piezoelectric ceramics in them. These piezoelectric ceramic materials have obtained the better effect in their newly and widely applied aspects, such as, acoustoelectric transducing; electrical to mechanical to electrical transducing; acoustooptic effect; electrooptic technique, and, piezoelectric ceramics for high voltage generators, ignition and detonation purposes, and some original applications (e.g., combining the electrorheological fluids) etc.. As far as appropriate measure of the improving sintering and other technique processes in present work is concerned, they also have reference value to electronic ceramics of having similar manufacturing technological process, such as capacitor ceramics, resistance ceramics, magnetic ceramics, and oxide ceramic superconducting materials, etc..
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De Nazare Oliveira de Oliveira, Zaline, Irinéia De Oliveira Bacelar Simplício, Andreza Dantas Ribeiro, Carla Suellem Sousa Araújo, Brenda dos Santos Coutinho, Leticia Gomes de Oliveira, Raiane Cristina Mourão do Nascimento, and Dara Marcela Gama dos Anjos. "Análise microbiológicas das maçanetas da clínica médica de um hospital público do interior da Amazônia." Saúde Coletiva (Barueri) 11, no. 65 (June 4, 2021): 6024–35. http://dx.doi.org/10.36489/saudecoletiva.2021v11i65p6024-6035.
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Objetivo: Avaliar as condições microbiológicas das maçanetas internas e externas das portas da unidade de clínica médica de um Hospital Público no interior da Amazônia, Município de Santarém, Oeste do Pará, Brasil. Método: Pesquisa exploratório-descritiva, quantitativa, realizado através de amostras da superfície de maçanetas das portas da clínica médica de um Hospital em Santarém-Pará. A análise microbiológica, foi realizada no agitador para dessorção das bactérias e a suspensão foi semeada por esgotamento. Resultados: Das 84 maçanetas, 26,2% apresentaram resultado microbiológico positivo, sendo encontrada em todos os casos a bactéria Staphylococcus sp. Quanto o material de cobertura, 25% das maçanetas estavam comprometido, sendo que, dentre os casos positivos na análise microbiológica, 18,2% das maçanetas estavam com a superfície prejudicada. Conclusão: Apesar do número de amostras positivas serem relativamente pequenos, é importante destacar ações voltada para a higienização dos fômites hospitalares, dado que estes podem funcionar como reservatórios de microrganismos patogênicos.
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Torres-Zamata, Gustavo, Aracel Erica Condori-Pacheco, Joel Fernández-Rojas, and Noé Benjamín Pampa-Quispe. "Efecto de la resistencia externa y área superficial del electrodo de grafito en la biodegradación de la materia orgánica y generación de bioelectricidad en celdas de combustible microbiano." Tecnología y ciencias del agua 11, no. 6 (November 1, 2020): 01–38. http://dx.doi.org/10.24850/j-tyca-2020-06-01.
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Las celdas de combustible microbiano (CCM) es una tecnología emergente para la generación de energía eléctrica a partir de materia biodegradable, teniendo como catalizador a los microorganismos. El objetivo fue evaluar la generación de bioelectricidad y remoción de la materia orgánica en las celdas de combustible microbiano (CCM) a partir del agua residual doméstica (ARD). Se operaron cinco CCM de doble cámara (anaerobia y aerobia) de tipo “H” a escala laboratorio de flujo batch, con volumen de 1 700 ml; las cámaras se conectaron a través de un puente salino (NCL y Agar Agar); se utilizaron electrodos de grafito (ánodo y cátodo) conectados por un cable de cobre como conductor eléctrico a una resistencia externa fija. Para evaluar la remoción de la materia orgánica, se trabajó con ARD de diferentes concentraciones de DQO y para el desempeño eléctrico se trabajó con tres áreas superficiales de electrodo y resistencias externas. Mediante ANOVA factorial y diseño factorial 22 al 95% nivel de confianza, la interacción de resistencia externa y área superficial del electrodo fueron significativas. La CCM2 destacó frente a las demás CCM al trabajar con resistencia de 50 Ω y área superficial de electrodo (AST-grafito) de 151 cm2, generando un voltaje promedio de 380 mV y 82.3% de eficiencia de remoción (DQO). Al trabajar con resistencias menores y mayor área superficial de electrodo en la CCM, se obtuvo una mayor generación de bioelectricidad y remoción de la materia orgánica a partir del agua residual doméstica (ARD), demostrando la viabilidad y sostenibilidad.
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Song, Jian, Libo Gao, Xiaoming Tao, and Lixiao Li. "Ultra-Flexible and Large-Area Textile-Based Triboelectric Nanogenerators with a Sandpaper-Induced Surface Microstructure." Materials 11, no. 11 (October 29, 2018): 2120. http://dx.doi.org/10.3390/ma11112120.
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Wearable triboelectric nanogenerators (TENGs) have attracted interest in recent years, which demand highly flexible, scalable, and low-cost features. Here, we report an ultra-flexible, large-scale and textile-based TENG (T-TENG) for scavenging human motion energy. The triboelectric layer was derived from the polydimethylsiloxane (PDMS) film with a cost-effective paper-induced rough surface via a facile doctor-blending technology. Ag-coated chinlon fabric (ACF) with ultra-flexible, large-scale and conductive characteristics was used as the electrode. The as-fabricated PDMS-based ACF (PACF) composites possess a 240 × 300 mm2 superficial area and remain highly flexible under mechanical squeezing, folding and even tearing deformation. The maximum output charge of ~21 μC and voltage of 80.40 V were therefore achieved to directly power 100 LEDs based on the high surface area of 762.73 mm2 which was rationally replicated from the sandpaper of the T-TENG. Moreover, the output voltage signal can be also used as a trigger signal of a movement sensor. Importantly, the explicit theoretical model corresponding to T-TENG was quantitatively investigated under different applied force, frequency and effective surface factor.
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Neretti, Gabriele, Arturo Popoli, Silvia Giuditta Scaltriti, and Andrea Cristofolini. "Real Time Power Control in a High Voltage Power Supply for Dielectric Barrier Discharge Reactors: Implementation Strategy and Load Thermal Analysis." Electronics 11, no. 10 (May 11, 2022): 1536. http://dx.doi.org/10.3390/electronics11101536.
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Atmospheric-pressure plasma treatments for industrial and biomedical applications are often performed using Dielectric Barrier Discharge reactors. Dedicated power supplies are needed to provide the high voltage frequency waveforms to operate these nonlinear and time-dependent loads. Moreover, there is a growing technical need for reliable and reproducible treatments, which require the discharge parameters to be actively controlled. In this work, we illustrate a low-cost power supply topology based on a push–pull converter. We perform experimental measurements on two different reactor topologies (surface and volumetric), showing that open loop operation of the power supply leads to a temperature and average power increase over time. The temperature increases by ΔTvol~120 °C and ΔTsup~70 °C, while the power increases by ΔPvol~78% and ΔPsup~60% for the volumetric (40 s) and superficial reactors (120 s), respectively. We discuss how these changes are often unwanted in practical applications. A simplified circuital model of the power supply–reactor system is used to infer the physical relation between the observed reactor thermal behavior and its electrical characteristics. We then show a control strategy for the power supply voltage to ensure constant average power operation of the device based on real-time power measurements on the high voltage side of the power supply and an empirical expression relating the delivered power to the power supply output voltage. These are performed with an Arduino Due microcontroller unit, also used to control the power supply. In a controlled operation the measured power stays within 5% of the reference value for both configurations, reducing the temperature increments to ΔTvol~80 °C and ΔTsup~44 °C, respectively. The obtained results show that the proposed novel control strategy is capable of following the transient temperature behavior, achieving a constant average power operation and subsequently limiting the reactor thermal stress.
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Pautasso, Diego, Tiago Soares Nogara, Carlos Renato Ungaretti, and Ana Maria Prestes Rabelo. "três dimensões da guerra comercial entre China e EUA." Carta Internacional 16, no. 2 (July 1, 2021): e1122. http://dx.doi.org/10.21530/ci.v16n2.2021.1122.
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O artigo argumenta que a Guerra Comercial entre EUA e China engloba três dimensões: num nível mais superficial, representa o recrudescimento do protecionismo estadunidense voltado à base eleitoral de Trump e à consequente barganha em relação à China para diminuir os déficits comerciais; no nível intermediário, a disputa pela liderança de importantes segmentos tecnológicosprodutivos; e no nível mais profundo, a própria contenda pela liderança do sistema internacional. Consequentemente, demonstramos que a disputa tecnológica sino-estadunidense no setor da infraestrutura 5G da empresa chinesa Huawei reflete uma competição mais abrangente pela própria liderança do sistema internacional.
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Xiao, Peng, and Zhi Kang Fan. "Vacuum Breakdown Behavior of CuWCr Composites." Materials Science Forum 569 (January 2008): 125–28. http://dx.doi.org/10.4028/www.scientific.net/msf.569.125.
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The Cu20W70Cr10 composites were fabricated by two methods which are the conventional powder metallurgy, and mechanical alloying to prepare WCr compound powders, followed by sintering and infiltration. The erosion behavior of CuWCr composites under breakdown was investigated. The surfaces of the composites before and after erosion and the mechanism of arc erosion were studied by scanning electron microscopy. The results show that the CuWCr composites prepared by mechanical alloying have superfine microstructure, uniform composition and high density, thus result in good characteristics of diffusing arcs and arc eroding endurance. Arc erosion zones are dispersive and uniform on the surfaces with some flat eroding pits. The Cu20W70Cr10 composites have excellent electrical properties such as high breakdown voltage, low chopping current and long arc life.