Aprender Arquitectura de Computadores con la herramienta Simula3MS

En este artículo se presenta la experiencia de uso de la herramienta Simula3MS en el laboratorio de las asignaturas de Arquitectura de Computadores en los estudios impartidos en la Facultad de Informática de la Universidade da Coruña y la Escuela Técnica Superior de Ingeniería de la Universidade de Santiago de Compostela. El objetivo de las prácticas es ilustrar, mediante un juego de ejercicios realizados sobre el simulador Simula3MS, cómo trabaja el procesador del computador. El simulador usa un subconjunto de instrucciones MIPS y varias configuraciones diferentes del procesador que se escogen según el objetivo de los ejercicios prácticos. En el artículo se describen los ejercicios que se proponen a los estudiantes en el laboratorio y se muestra un análisis sobre el impacto que ha tenido el uso del simulador en la actividad docente.Peer Reviewe

Experimental research of the effect of surface orientation on the subcooled flow nucleate boiling of water at low pressure

The toughening emission standards and the costs saving requirements are pushing to the limits the design of compact heat exchangers in the automotive industry, meaning that today’s heat exchangers need to operate with a controlled level of boiling in their coolant side. Most of the experimental literature available tackle boiling in horizontal flat plates or vertical tubes, while the information regarding other orientations is much scarcer. However, in a compact heat exchanger all orientations are present therefore orientation parametrizations in boiling models are particularly important since upper-heating orientations have a strong influence on heat transfer mechanism and the critical heat flux due to the cancelation of the bubbles floatability forces that help their departure. Therefore the limiting heat flux in those parts is generally governed at boiling orientations not determined with precision. The experimental work presented in this paper analyses the dependence of the heat transfer coefficient with the inclination of the heated surface under subcooled boiling regime. Due to the heating method selected, the test part consists in an AISI 316 thin strip with a thickness of 0.5 mm brazed to a copper base, to ensure an industry-like heat exchange material as primary surface but avoiding unmanaged temperatures and heating powers. Experimental tests have been carried out on a single face heated rectangular channel under several operating conditions of bulk velocity, temperature, pressure and flow orientation: 0.1-0.9 (m/s) – 76.5-93.5 (°C) – 110-190 (kPa) – 0- 180 (°), to cover some of the most common conditions found in the automotive compact heat exchanger industry. The heat flux employed in each test ranged from 0.1 to more than 1 MW/m². After the data analysis some main dependences were identified and suggested that a global boiling model should include some parameters accounting for the relative orientation of the heated part and the coolant flow. This could be a valuable tool during the development of an automotive heat exchanger in which nucleate boiling is present.Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016

CFD Transient Simulation of a Breathing Cycle in an Oral-Nasal Extrathoracic Model

Knowledge of respiratory flow behaviour is important in many respiratory medical fields. The usefulness of numerical models in providing a better understanding of flow phenomena has made the Computational Fluid Dynamics (CFD) an indispensable research tool due to the difficulty of measuring in vivo data. In this research, the extrathoracic airways and the upper tracheobronchial region, trachea and main bronchus bifurcation were modelled. Oral and nasal breathing routes have been considered under steady and cyclic unsteady conditions. A realistic far boundary condition was imposed as the flow inlet. Different ventilation levels and frequencies were simulated. The model presented has been validated successfully by two parts: nasal and oral models. The airflow distributions through oral and nasal routes were determined, analysed and compared under different breathing conditions. The flow behaviour and respiratory effort during inhalation and exhalation phases change from rest to high activity; the flow can increase 40% with the same respiratory effort, opening the mouth during the inspiration. Significant differences in turbulent intensity contours in steady and unsteady cases have been observed. This study demonstrated the relevance of considering different breathing patterns and more realistic unsteady conditions

Anti-biofilm multi drug-loaded 3D printed hearing aids

Over 5% of the world's population has disabling hearing loss, which affects approximately one third of individuals over 65 years. Hearing aids are commonly used in this population group, but prolonged use of these devices may cause ear infections. We describe for the first time, the use of 3D printing to fabricate hearing aids loaded with two antibiotics, ciprofloxacin and fluocinolone acetonide. Digital light processing 3D printing was employed to manufacture hearing aids from two polymer resins, ENG hard and Flexible. The inclusion of the antibiotics did not affect the mechanical properties of the hearing aids. All multi-drug-loaded devices exhibited a hydrophilic surface, excellent blood compatibility and anti-biofilm activity against P. aeruginosa and S. aureus. Hearing aids loaded with ciprofloxacin (6% w/w) and fluocinolone acetonide (0.5% w/w) sustained drug release for more than two weeks and inhibited biofilm formation on the surface of the devices and bacteria growth in the surrounding medium. In summary, this work highlights the potential of vat photopolymerization 3D printing as a versatile manufacturing approach to fabricate high-fidelity patient-specific medical devices with anti-bacterial properties

Biomechanical characteristics of different methods of neo-chordal fixation to the papillary muscles

Background and Aim of the Study Several techniques have been described for neo-chordal fixation to the papillary muscles without any reported clinical differences. The objective of this study is to compare in vitro the biomechanical properties of four of these common techniques. Methods We studied the biomechanical properties of expanded polytetrafluoroethylene neo-chordal fixation using four techniques: nonknotted simple stitch, nonknotted figure-of-eight stitch, knotted pledgeted mattress stitch, and knotted pledgeted stitch using commercially available prefabricated loops. Neo-chordae were submitted to a total of 20 traction-relaxation cycles with incremental loads of 1, 2, and 4 N. We calculated the elongation, the force-strain curve, elasticity, and the maximum tolerated load before neo-chordal failure. Results The elongation of the neo-chordae was lowest in the simple stitch followed by the figure-of-eight, the pledgeted mattress, and he commercially prefabricated loops (p < .001). Conversely, the elastic modulus was highest in the simple stitch followed by the figure-of-eight, the pledgeted mattress, and the prefabricated loops (p < .001). The maximum tolerated load was similar with the simple stitch (28.87 N) and with the figure-of-eight stitch (31.39 N) but was significantly lower with the pledgeted mattress stitch (20.51 N) and with the prefabricated loops (7.78 N). Conclusion In vitro, neo-chordal fixation by nonknotted simple or nonknotted figure-of-eight stitches resulted in less compliance as opposed to the use of knotted pledgeted stitches. Fixation technique seemed to influence neo-chordal biomechanical properties, however, it did not seem to affect the strength of the suture when subjected to loads within physiological rangesS

Micelles of Progesterone for Topical Eye Administration: Interspecies and Intertissues Differences in Ex Vivo Ocular Permeability

Progesterone (PG) may provide protection to the retina during retinitis pigmentosa, but its topical ocular supply is hampered by PG poor aqueous solubility and low ocular bioavailability. The development of efficient topical ocular forms must face up to two relevant challenges: Protective barriers of the eyes and lack of validated ex vivo tests to predict drug permeability. The aims of this study were: (i) To design micelles using Pluronic F68 and Soluplus copolymers to overcome PG solubility and permeability; and (ii) to compare drug diffusion through the cornea and sclera of three animal species (rabbit, porcine, and bovine) to investigate interspecies differences. Micelles of Pluronic F68 (3–4 nm) and Soluplus (52–59 nm) increased PG solubility by one and two orders of magnitude, respectively and exhibited nearly a 100% encapsulation efficiency. Soluplus systems showed in situ gelling capability in contrast to the low viscosity Pluronic F68 micelles. The formulations successfully passed the hen’s egg-chorioallantoic membrane test (HET-CAM) test. PG penetration through rabbit cornea and sclera was faster than through porcine or bovine cornea, although the differences were also formulation-dependent. Porcine tissues showed intermediate permeability between rabbit and bovine. Soluplus micelles allowed greater PG accumulation in cornea and sclera whereas Pluronic F68 promoted a faster penetration of lower PG dosesThis research was funded by MINECO [SAF2017-83118-R] (Spain), Agencia Estatal de Investigación (AEI, Spain), Xunta de Galicia [AEMAT ED431E 2018/08], and European Regional Development Fund (FEDER). Predoctoral grants CEU Cardenal Herrera University FPI CEU-UCH, mobility grant CEINDO international doctoral school, CEU-Cardenal Herrera University [INDI 19/28]S

Empty Urbanism: the bursting of the Spanish housing bubble

The depth of the Spanish housing crisis manifests itself in the collapse of construction activity and in the amount of housing and land stocks. The geography of the crisis shows its widespread nature, and the intensity of the previous bubble explains spatial differences. Resulting from this collapse are some problematic areas of 'empty urbanism'. An enormous land bubble, emerging from the peculiar Spanish urban development model, was a key factor in the impacts - caused by the crisis - on the territory and land-use plans. The crisis has demonstrated the unsustainability of this and the urgency of change in the existing land-use plans

Powder Compaction: Compression Properties of Cellulose Ethers

Effective development of matrix tablets requires a comprehensive understanding of different raw material attributes and their impact on process parameters. Cellulose ethers (CE) are the most commonly used pharmaceutical excipients in the fabrication of hydrophilic matrices. The innate good compression and binding properties of CE enable matrices to be prepared using economical direct compression (DC) techniques. However, DC is sensitive to raw material attributes, thus, impacting the compaction process. This article critically reviews prior knowledge on the mechanism of powder compaction and the compression properties of cellulose ethers, giving timely insight into new developments in this field