1,342 research outputs found
Motivación y satisfacción laboral en el personal del servicio de laboratorio clínico, Hospital Regional “Virgen de Fátima”, Chachapoyas, 2015
La presente investigación fue de enfoque cuantitativo; de nivel relacional; de tipo: observacional; prospectivo, transversal y analítico. Cuyo objetivo fue: determinar la relación que existe entre la motivación y la satisfacción laboral en el personal del Servicio de Laboratorio Clínico, Hospital Regional “Virgen de Fátima”, Chachapoyas, 2015. El universo muestral estuvo conformado por 13 profesionales del Servicio de Laboratorio Clínico, Hospital Regional “Virgen de Fátima”. Se utilizó el método hipotético deductivo. Para recabar la información se utilizó el formulario del cuestionario de motivación y satisfacción laboral. Para el análisis de los resultados se utilizó la prueba estadística no paramétrica del ji - cuadrado. Los resultados evidencian que el 84.6% se muestran poco motivados laboralmente y solo el 15.4% motivados; además el 53.8% se muestran poco satisfechos laboralmente y el 46.2% satisfechos. Así mismo el 53.8% se muestran poco satisfechos y poco motivados laboralmente, el 30.8% se muestran satisfechos pero poco motivados laboralmente y el 15.4% se muestran satisfechos y motivados laboralmente. Las hipótesis fueron contrastadas con la prueba estadística no paramétrica del Ji – cuadrado cuyo valor fue: X2 = 2.758; GL = 1; α= 0.097 > 0.05; con este resultado se contrastó la hipótesis nula. En conclusión, el personal del Servicio de Laboratorio Clínico del Hospital Regional “Virgen de Fátima”, en más de las tres cuartas partes se muestran poco motivados laboralmente y más de la mitad poco satisfechos. No existe ninguna relación entre la motivación laboral y la satisfacción laboral.Tesi
Low temperature effect on impact energy absorption capability of PEEK composites
This paper describes the results of an experimental investigation which analyses the impact behavior at low temperature of polyether ether ketone (PEEK) and its short carbon fiber reinforced composite (SCFR PEEK). These polymer materials are widely employed in aeronautical applications subjected to impact loadings in which the energy absorption capability is an aspect that should be taken into account. The energy absorption capability can drastically decrease if temperatures near to the ductile-to-brittle transition temperature of polymeric matrix are reached. In this work, a set of perforation tests has been conducted covering a testing temperature range from -75 degrees C to +25 degrees C and an impact kinetic energy range from 11 J to 175 1 including typical values considered in impact loadings at aeronautical flight speeds. Energy absorption capability, damage extension and failure mechanisms have been quantified and reported. At low temperatures, a ductile-to-brittle transition was found in PEEK unfilled resulting in a suddenly change of its mechanical impact behavior affecting the energy absorption capability. In case of SCFR PEEK composite, a brittle behavior was observed for the whole temperature range considered and its energy absorption capability decreases drastically at lower temperatures. The brittleness of PEEK and SCFR PEEK at low temperature will limit the application of this composite in aeronautical structures exposed to impact.The researchers of the University Carlos III of Madrid are indebted to the Ministerio de Ciencia e Innovación de España (Project DPI/2011-24068) and to the Ministerio de Economía y Competitividad de España (Project DPI/2014-57989-P) for financial support towards part of this work
Investigation of mechanical impact behavior of short carbon-fiber-reinforced PEEK composites
This paper describes the results of an experimental and numerical investigation of the impact behavior of short carbon fiber reinforced polyether-ether-ketone (SCFR PEEK) composites. The biocompatibility of PEEK and its short fiber composites, their rapid processing by injection molding and suitability for modern imaging have supported technological advances in prosthetic implants used in orthopedic medicine. Surgical implants, including hip and cranial implants, can experience clinically significant impact loading during medical installation and useful life. While the incorporation of short fibers in a thermoplastic matrix can produce significant improvements in stiffness and strength, it can also cause a marked reduction in ductility, making study of their energy absorption capability essential. In this work, the mechanical impact behavior of PEEK composites reinforced with polyacrylonitrile (PAN) short carbon fibers 30% in weight is compared with unfilled PEEK. The perforation tests conducted covered an impact kinetic energy range from 21 J to 131 J, equivalent to the range observed in a fall, the leading cause of hip fractures. Energy absorption capability, damage extension and failure mechanism have been quantified and reported. A numerical modeling that includes homogenization of elastic material and anisotropic damage is presented and validated with experimental data. At all impact energies, SCFR PEEK composites showed a brittle failure and their absorption energy capability decreases drastically in comparison with unfilled PEEK. (C) 2015 Elsevier Ltd. All rights reserved.The researchers of the University Carlos III of Madrid are indebted to the Ministerio de Ciencia e Innovación de España (Project DPI/2011-24068) and to the Ministerio de Economía y Competitividad de España (Project DPI/2014-57989-P) for financial support towards part of this work. The researchers are indebted to LATI Company for PEEK material supplie
Influence of stress state on the mechanical impact and deformation behaviors of aluminum alloys
Under impact loading conditions, the stress state derived from the contact between the projectile and the target, as well as from the subsequent mechanical waves, is a variable of great interest. The geometry of the projectile plays a dertermining role in the resulting stress state in the targeted structure. In this regard, different stress states lead to different failure modes. In this work, we analyze the influence of the stress state on the deformation and failure behaviors of three aluminum alloys that are commonly used in the aeronautical, naval, and automotive industries. To this purpose, tension-torsion tests are performed covering a wide range of stress triaxialities and Lode parameters. Secondly, the observations from these static tests are compared to failure mode of the same materials at high impact velocities tests with the aim of analysing the role of stress state and strain rate in the mechanical response of the aluminum plates. Experimental impacts are conducted with different projectile geometries to allow for the analysis of stress states influence. In addition, these experiments are simulated by using finite element models to evaluate the predictive capability of three failure criteria: critical plastic deformation, Johnson-Cook, and Bai-Wierzbicki.The researchers of the University CarlosIII are indebted to the Ministerio de Economía y Competitividad de España (Project DPI2014-57989-P) and Vicerrectorado de Política Científica UC3M (Project 2013-00219-002) for the financial suppor
Perforation mechanics of 2024 aluminium protective plates subjected to impact by different nose shapes of projectiles
This paper focuses on the mechanical behaviour of aluminium alloy 2024-T351 under impact loading. This study has been carried out combining experimental and numerical techniques. Firstly, experimental impact tests were conducted on plates of 4 mm of thickness covering impact velocities from 50 m/s to 200 m/s and varying the stress state through the projectile nose shape: conical, hemispherical and blunt. The mechanisms behind the perforation process were studied depending on the projectile configuration used by analyzing the associated failure modes and post-mortem deflection. Secondly, a numerical study of the mechanical behaviour of aluminium alloy 2024-T351 under impact loading was conducted. To this end, a three-dimensional model was developed in the finite element solver ABAQUS/Explicit. This model combines Lagrangian elements with Smoothed Particle Hydrodynamics (SPH) elements. A good correlation was obtained between numerical and experimental results in terms of residual and ballistic limit velocities
An overview process analysis of the aromatic-aliphatic separation by liquid–liquid extraction with ionic liquids
There is a lack of knowledge on comprehensive studies when dealing with ionic liquids and extraction processes. In this work, the computational COSMO-based/Aspen multiscale methodology is applied to perform a comprehensive process analysis over a wide set of 100 common ILs after properly validating against all reliable data published, in the representative field of the aromatic/aliphatic separation. The analysis describes: i) the evolution from extractive properties to extractor behavior; ii) the influence of the rigor of the model -binary (n-heptane + toluene) or multicomponent (pyrolysis gasoline) and the process description, namely extractor or complete process with recycling streams; iii) the role of the IL at commercial specifications; iv) the role of the separation train. Main results highlight: i) leading role of mass-based distribution ratio to reduce energy consumption to assess a commercial recovery; ii) selecting an IL with a minimum selectivity required within the more efficient separation train to achieve specifications at the lower energy consumption. Therefore, this work presented a clear guide to properly select the IL extractive properties at process scale and commercial specifications, together with the development of an efficient separation train, as the best approac
Biodistribution of Liposome-Encapsulated Bacteriophages and Their Transcytosis During Oral Phage Therapy
This study sheds light on the biodistribution of orally administered, liposome-encapsulated bacteriophages, and their transcytosis through intestinal cell layers. Fluorochrome-labeled bacteriophages were used together with a non-invasive imaging methodology in the in vivo visualization of bacteriophages in the stomach and intestinal tract of mice. In those studies, phage encapsulation resulted in a significant increase of the labeled phages in the mouse stomach, even 6 h after their oral administration, and without a decrease in their concentration. By contrast, the visualization of encapsulated and non-encapsulated phages in the intestine were similar. Our in vivo observations were corroborated by culture methods and ex vivo experiments, which also showed that the percentage of encapsulated phages in the stomach remained constant (50%) compared to the amount of initially administered product. However, the use of conventional microbiological methods, which employ bile salts to break down liposomes, prevented the detection of encapsulated phages in the intestine. The ex vivo data showed a higher concentration of non-encapsulated than encapsulated phages in liver, kidney, and even muscle up to 6 h post-administration. Encapsulated bacteriophages were able to reach the liver, spleen, and muscle, with values of 38% ± 6.3%, 68% ± 8.6%, and 47% ± 7.4%, respectively, which persisted over the course of the experiment. Confocal laser scanning microscopy of an in vitro co-culture of human Caco-2/HT29/Raji-B cells revealed that Vybrant-Dil-stained liposomes containing labeled bacteriophages were preferably embedded in cell membranes. No transcytosis of encapsulated phages was detected in this in vitro model, whereas SYBR-gold-labeled non-encapsulated bacteriophages were able to cross the membrane. Our work demonstrates the prolonged persistence of liposome-encapsulated phages in the stomach and their adherence to the intestinal membrane. These observations could explain the greater long-term efficacy of phage therapy using liposome-encapsulated phages
COSMO-based/Aspen Plus process simulation of the aromatic extraction from pyrolysis gasoline using the {[4empy][NTf2] + [emim][DCA]} ionic liquid mixture
The ionic liquids (ILs) have been widely studied as potential replacements of conventional solvents in the extraction of aromatic hydrocarbons from alkanes. However, most of the literature is focused in obtaining liquid-liquid equilibria experimental data without studying the complete extraction and IL regeneration process. In this paper, a computer-aided methodology combining COSMO-based molecular simulations and Aspen Plus process simulations has been used to study the extraction process of aromatic hydrocarbons from pyrolysis gasoline employing a binary mixture of 1-ethyl-4-methylpyridinium bis(trifluoromethylsulfonyl)imide ([4empy][NTf2]) and the 1-ethyl-3-methylimidazolium dicyanamide ([emim][DCA]) ILs as solvent. An extensive comparison (more than 600 points) between experimental data and the predictions obtained by the COSMO-based thermodynamic model of liquid–liquid and vapor–liquid equilibria and ILs physical properties was made for validation purposes. Process simulations were performed in three system configurations: with one, two, or three flash distillations in the IL recovery section. The potential advantage of using binary IL-IL mixture as extracting solvent was studied in the whole range of composition. The configuration with three flash distillations and the binary IL-IL mixture with a 75% of [4empy][NTf2] were selected as the optimal conditions to increase aromatic recovery and purity, improving the separation performance respect to the neat ILsThe authors are grateful to Ministerio de Economía y Competitividad (MINECO) of Spain for financial support of Projects CTQ2014-52288-R and CTQ2014–53655-R and to Comunidad Autónoma de Madrid for the Project S2013/MAE-2800. Noemí Delgado-Mellado also thanks MINECO for awarding them an FPI grant (Reference BES–2015–072855) and Marcos Larriba also thanks MINECO for awarding him a Juan de la Cierva-Formación Contract (Reference FJCI-2015-25343). Pablo Navarro thanks Fundação para a Ciência e a Tecnologia for awarding him a postdoctoral grant (Reference SFRH/BPD/117084/2016)
Transmit–receive parabolic reflectarray to generate two beams per feed for multispot satellite antennas in Ka-band
This contribution describes the design of a multibeam parabolic reflectarray to produce two adjacent beams per feed in orthogonal circular Polarization (CP) simultaneously at transmit (Tx) and receive (Rx) frequencies in Ka-band. The Variable Rotation Technique (VRT) has been applied to reflectarray cells based on two types of resonant elements, which makes it possible to provide orthogonal beams at Tx and Rx, as well as to implement an in-band optimization procedure to reduce the cross-polarization. A 90-cm parabolic reflectarray has been designed, manufactured and tested to produce multiple adjacent beams in RHCP and LHCP at both 20 and 30 GHz. The results
are satisfactory and validate the concept of generating two spaced beams in orthogonal CP by a single feed, changing the polarization of the beam between Tx and Rx. This concept can be suitable for multispot satellites in Ka-band, enabling to halve the number of onboard antennas and feedsAgencia Estatal de Investigación | Ref. TEC2016-75103-C2-1-RAgencia Estatal de Investigación | Ref. FJCI-2016-29943European Space Agency | Ref. 4000117113/16/NL/A
Cocina de Nayarit: Secretos del Norte del Estado
El estado de Nayarit es rico por su tierra y su variedad de cultivos y alimentos. En la región norte de Nayarit, abunda la pesca, los frutos tropicales y los animales silvestres, además es una zona costera con muchas playas. La cocina típica de la región (del norte) ha sido influenciada por éstos alimentos bases de la producción de ésta zona
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