Synthesis of Silver nanoparticles (AgNPs) with Antibacterial Activity

The synthesis of nanomaterials is currently one of the most active in nanoscience branches; especially those help improve the human quality life. Silver nanoparticles (AgNPs) are an example of this as it is known to have inhibitory and bactericidal effects. In this work, we report the synthesis of silver nanoparticles by chemical reduction method of silver nitrate (AgNO3) from aqueous solution, using a mix of polivinyl pyrrolidone (PVP) - Aloe Vera as reducing agent and for stabilization and control of particle size. Silver nanoparticles obtained were characterized by Scanning Electron Microscopy (SEM), UV-visible spectroscopy and measurements using Zetasizer Nano ZS were applied to size estimation. The existence of surface plasmon resonance peak at λmax ∼ 420 nm is evidence of silver nanoparticles formation. It was possible to standardize an appropriate protocol for the evaluation of bactericidal activity of the nanoparticles, for mesophilic microorganisms. Bactericidal activity above 90% against these kinds of bacteria was demonstrated. © Published under licence by IOP Publishing Ltd

QoSatAr: a cross-layer architecture for E2E QoS provisioning over DVB-S2 broadband satellite systems

This article presents QoSatAr, a cross-layer architecture developed to provide end-to-end quality of service (QoS) guarantees for Internet protocol (IP) traffic over the Digital Video Broadcasting-Second generation (DVB-S2) satellite systems. The architecture design is based on a cross-layer optimization between the physical layer and the network layer to provide QoS provisioning based on the bandwidth availability present in the DVB-S2 satellite channel. Our design is developed at the satellite-independent layers, being in compliance with the ETSI-BSM-QoS standards. The architecture is set up inside the gateway, it includes a Re-Queuing Mechanism (RQM) to enhance the goodput of the EF and AF traffic classes and an adaptive IP scheduler to guarantee the high-priority traffic classes taking into account the channel conditions affected by rain events. One of the most important aspect of the architecture design is that QoSatAr is able to guarantee the QoS requirements for specific traffic flows considering a single parameter: the bandwidth availability which is set at the physical layer (considering adaptive code and modulation adaptation) and sent to the network layer by means of a cross-layer optimization. The architecture has been evaluated using the NS-2 simulator. In this article, we present evaluation metrics, extensive simulations results and conclusions about the performance of the proposed QoSatAr when it is evaluated over a DVB-S2 satellite scenario. The key results show that the implementation of this architecture enables to keep control of the satellite system load while guaranteeing the QoS levels for the high-priority traffic classes even when bandwidth variations due to rain events are experienced. Moreover, using the RQM mechanism the user’s quality of experience is improved while keeping lower delay and jitter values for the high-priority traffic classes. In particular, the AF goodput is enhanced around 33% over the drop tail scheme (on average)

Uso de hábitats y recursos florales de Chalybura buffonii caeruleogaster (Aves: Trochilidae) en un sector del piedemonte llanero, Villavicencio, Colombia

The hummingbird Chalybura buffonii caeruleogaster is a subspecies of which little is known about its ecology, including trophic aspects. For this reason, we seek to contribute to the knowledge of the use of habitats and plant species used as food by C. b. caeruleogaster. We carry out samplings from March to September 2018, in the dry and rainy seasons in localities of the Piedemonte Llanero. We registered 16 adult individuals, 10 males and six females, of which 11 were observed in the rainy season and five in the dry season. The most used habitats were the urban fabric, the secondary vegetation and the mosaic of crops. We registered 10 species that formed the floral resource of C. b. caeruleogaster. Within these plant species ornamental and native plants of the region were registered. This provides information on the use of generalized resources by the species. The exposed results contribute to the knowledge of the ecology of the species (subspecies), its elusive nature and the potential of amplitude of its dietary spectrum. Recommendations are proposed to evaluate the ecological processes and mechanisms that shape the population size (its rarity or elusive nature) and the detection capacity in natural environments.El colibrí Chalybura buffonii caeruleogaster es una subespecie de cuya ecología se conoce poco, incluidos aspectos tróficos. Por esto se buscó aportar al conocimiento de uso de hábitats y especies vegetales usadas como alimento por C. b. caeruleogaster. Con ese fin se realizaron muestreos de marzo a septiembre de 2018 en las épocas secas y de lluvia en localidades del piedemonte llanero. Se obtuvieron registros de 16 individuos adultos, 10 machos y seis hembras, de los cuales 11 se observaron en la época de lluvias, y cinco, en la época seca. Los hábitats más usados fueron el tejido urbano, la vegetación secundaria y el mosaico de cultivos. Asimismo, se registraron 10 especies que formaron el recurso floral de C. b. caeruleogaster, entre las que se incluyen plantas ornamentales y nativas de la región. Esto brinda información sobre el aprovechamiento de recursos generalizados por parte de la especie. Los resultados expuestos aportan al conocimiento de la ecología de la especie (subespecie), de su carácter elusivo y del potencial de amplitud de su espectro dietario.  Se propone como recomendación evaluar los procesos y mecanismos ecológicos que moldean el tamaño poblacional (su rareza o carácter elusivo) y la capacidad de detección en ambientes naturales

Crianza artificial de terneros y eficiencia en la utilización de la úrea

Muchos sistemas para la cría de terneros se han ensayado en diferentes países, empleando reemplazo total 0 parcial de La alimentación láctea por sustitutos que puedan supl1r los requerimientos para el desarrollo normal de los animales, la gran escasez de leche en la actualidad tanto para el consumo humano como para la industria procesadora, es una de las condiciones que conduce a buscar Sistemas de cría de terneros con reducidas cantidades de leche por cortos períodos de alimentación láctea, dando como resultado una mayor cantidad de leche disponible, que puede aumentar los niveles de venta en los mercados, ocasionando así la capacidad para un mayor consumo por persona y al mismo tiempo haciendo más rentables las explotaciones ganadera

Design of an electronic voting system using A blockchain network

Design of a scalable electronic voting system, which, based on a generic model designed for this application called voting cell, guarantees the integrity of the information through the use of a private network Blockchain. For the validation of the system, the implementation of a cell was carried out, for which fifty voters and three voting options were enabled. The stored data was intentionally modified to corroborate the error correction method used by the block chain networks and thus ensure the integrity of the voting system results

The 21 cm Signature of Shock Heated and Diffuse Cosmic String Wakes

The analysis of the 21 cm signature of cosmic string wakes is extended in several ways. First we consider the constraints on $G\mu$ from the absorption signal of shock heated wakes laid down much later than matter radiation equality. Secondly we analyze the signal of diffuse wake, that is those wakes in which there is a baryon overdensity but which have not shock heated. Finally we compare the size of these signals compared to the expected thermal noise per pixel which dominates over the background cosmic gas brightness temperature and find that the cosmic string signal will exceed the thermal noise of an individual pixel in the Square Kilometre Array for string tensions $G\mu > 2.5 \times 10^{-8}$.Comment: 10 pages, 4 figures, Appendix added, version published in JCA

FREQUENCY OF PATHOGENS ISOLATED IN CLINICAL CASES OF CANINE PIODERMA AND ITS ANTIMICROBIAL SUSCEPTIBILITY

La dermatitis bacteriana canina, comúnmente conocida como piodermia, es una de las principales enfermedades dermatológicas observadas en la clínica veterinaria. El presente estudio retrospectivo tuvo como objetivo determinar la frecuencia de los diferentes agentes bacterianos involucrados con esta enfermedad y los antibióticos que presentan mejor actividad inhibidora frente a los principales microorganismos patógenos. Para tal fin, se analizaron los registros de resultados de aislamiento bacteriano y antibiograma del Laboratorio de Bacteriología de la Facultad de Medicina Veterinaria de la Universidad Nacional Mayor de San Marcos, Lima, durante el periodo 2000-2006. El Staphlococcus intermedius fue la especie más aislada (70.6%). Los antibióticos más efectivos fueron de la familia de las cefalosporinas como el ceftiofur y la cefalexina, mientras que la penicilina fue la que presentó mayor índice de resistencia.The canine bacterial dermatitis, commonly known as pyoderma is one of the main skin diseases in the veterinary practice. The present retrospective study had the objective to determine the frequency of the bacteriological agents involved with the disease and the antibiotics that show better antimicrobiobial susceptibility. Laboratory records of bacterial isolation and antibiogram of the Laboratory of Bacteriology of the Veterinary Medicine Faculty, San Marcos University, Lima, were analyzed. Staphlococcus intermedius was the most commonly isolated species (70.6%). The most effective antibiotics were from the Cephalosporin family, especially the ceftiofur and cefalexin, and penicillin was the antibiotic with higher resistance index

Determinación mediante hs-spme/gc-ms, de la composición química de la fragancia y el absoluto de las flores de posoqueria latifolia

En este trabajo se estudió la composición química del absoluto y de la fragancia de las flores de Posoqueria latifolia. La fragancia se muestreó in vivo mediante HS-SPME, encontrándose como compuestos mayoritarios el acetato de 3-Zhexenilo (80.7 por ciento), y el acetato de hexilo (5.8 por ciento). El absoluto fue obtenido a partir del concreto de las flores mediante extracción etanólica a 38 ºC y analizado por GC-MS. Los compuestos mayoritarios del absoluto fueron el 1-pentacosano (26.2 por ciento), salicilato de bencilo (7.4 por ciento), tricosano (5.9 por ciento), ácido linolénico (4.8 por ciento), pentacosano (4.5 por ciento), benzoato de bencilo (3.3 por ciento) y eugenol (2.8 por ciento)

Determinación mediante hs-spme/gc-ms, de la composición química de la fragancia y el absoluto de las flores de posoqueria latifolia

En este trabajo se estudió la composición química del absoluto y de la fragancia de las flores de Posoqueria latifolia. La fragancia se muestreó in vivo mediante HS-SPME, encontrándose como compuestos mayoritarios el acetato de 3-Zhexenilo (80.7 por ciento), y el acetato de hexilo (5.8 por ciento). El absoluto fue obtenido a partir del concreto de las flores mediante extracción etanólica a 38 ºC y analizado por GC-MS. Los compuestos mayoritarios del absoluto fueron el 1-pentacosano (26.2 por ciento), salicilato de bencilo (7.4 por ciento), tricosano (5.9 por ciento), ácido linolénico (4.8 por ciento), pentacosano (4.5 por ciento), benzoato de bencilo (3.3 por ciento) y eugenol (2.8 por ciento)