Design of Sustainable Aluminium-Based Feedstocks for Composite Extrusion Modelling (CEM).

Additive manufacturing (AM) has become one of the most promising manufacturing techniques in recent years due to the geometric design freedom that this technology offers. The main objective of this study is to explore Composite Extrusion Modelling (CEM) with aluminium as an alternative processing route for aluminium alloys. This process allows for working with pellets that are deposited directly, layer by layer. The aim of the technique is to obtain aluminium alloy samples for industrial applications with high precision, without defects, and which are processed in an environmentally friendly manner. For this purpose, an initial and preliminary study using powder injection moulding (PIM), necessary for the production of samples, has been carried out. The first challenge was the design of a sustainable aluminium-based feedstock. The powder injection moulding technique was used as a first approach to optimise the properties of the feedstock through a combination of water-soluble polymer, polyethyleneglycol (PEG), and cellulose acetate butyrate (CAB) wich produces low CO2 emissions. To do this, a microstructural characterisation was carried out and the critical solid loading and rheological properties of the feedstocks were studied. Furthermore, the debinding conditions and sintering parameters were adjusted in order to obtain samples with the required density for the following processes and with high geometrical accuracy. In the same way, the printing parameters were optimised for proper material deposition.

An Efficient Procedure for Bonding Piezoelectric Transducers to Thermoplastic Composite Structures for SHM Application and Its Durability in Aeronautical Environmental Conditions.

Piezoceramic transducers (PCTs) bonded to carbon fiber-reinforced plastic (CFRP) composite structures must be durable as well as remain properly bonded to the structure in order to provide reliable data for accurate guided-wave-based structural health monitoring (SHM) of aeronautical components. The current method of bonding transducers to composite structures through epoxy adhesives faces some shortcomings, such as difficult reparability, lack of weldability, longer curing cycles, and shorter shelf life. To overcome these shortcomings, a new efficient procedure for bonding the transducers to thermoplastic (TP) composite structures was developed by utilizing TP adhesive films. Application-suitable TP films (TPFs) were identified and characterized through standard differential scanning calorimetry (DSC) and single lap shear (SLS) tests to study their melting behavior and bonding strength, respectively. Special PCTs called acousto-ultrasonic composite transducers (AUCTs) were bonded to high-performance TP composites (carbon fiber Poly-Ether-Ether-Ketone) coupons with a reference adhesive (Loctite EA 9695) and the selected TPFs. The integrity and durability of the bonded AUCTs in aeronautical operational environmental conditions (AOEC) were assessed in accordance to the standard Radio Technical Commission for Aeronautics DO-160. The AOEC tests performed were operating low and high temperatures, thermal cycling, hot-wet, and fluid susceptibility tests. The health and bonding quality of the AUCTs were evaluated by the electro-mechanical impedance (EMI) spectroscopy method and ultrasonic inspections. The AUCT defects were created artificially and their influence on the susceptance spectra (SS) was measured to compare them with the AOEC-tested AUCTs. The results show that a small change occurred in the SS characteristics of the bonded AUCTs in all of the adhesive cases after the AOEC tests. After comparing the changes in SS characteristics of simulated defects with that of the AOEC-tested AUCTs, the change is relatively smaller and therefore it can be concluded that no serious degradation of the AUCT or the adhesive layer has occurred. It was observed that the most critical tests among the AOEC tests are the fluid susceptibility tests, which can cause the biggest change in the SS characteristics. Comparing the performance of the AUCTs bonded with the reference adhesive and the selected TPFs in the AOEC tests, it was seen that some of the TPFs, e.g., Pontacol 22.100 outperforms the reference adhesive, while the other TPFs have similar performance to that of the reference adhesive. Therefore, in conclusion, the AUCTs bonded with the selected TPFs can withstand the operational and environmental conditions of an aircraft structure, and hence, the proposed procedure is easily installed, reparable, and a more reliable method of bonding sensors to aircraft structures.

Accidentalidad vial por consumo de drogas y alcohol: Estado actual / Road traffic accidents related to drugs and alcohol: Current situation

El consumo de alcohol se reconoce como causa importante de accidentes de tránsito por el efecto depresor sobre el sistema nervioso central. Aunque las drogas recreacionales o ilegales tienen una acción similar es poco lo que se conoce sobre su relación con la accidentalidad vial. Objetivo: conocer la situación actual en Colombia y el mundo sobre los efectos del alcohol y las sustancias psicoactivas ilegales en el sistema nervioso central como posibles causas de accidentes de tránsito. Métodos: revisión de la literatura en bases electrónicas utilizando los términos DeCS y MeSH: street drugs, designed drugs, ethanol, cocaine,cannabinoides, amphetamines, injuries, accident traffic y automobile driving. Resultados: algunos estudios en especial en Estados Unidos, se reporta una relación estrecha entre el consumo de sustancias psicoactivas y la accidentalidad vial, con cifras cercanas a las del alcohol. En México también se ha demostrado esta relación. En Colombia la mayoría de publicaciones sobre factores de accidentalidad vial no diferencian el consumo de alcohol de las sustancias psicoactivas, lo cual refleja la falta de programas de promoción y prevención sobre el riesgo de conducir bajo la acción de estas sustancias. Los exámenes para determinar su presencia no se ordenan en forma rutinaria y por los datos existentes no reflejan los costos reales derivados de la atención a víctimas de accidentes de tránsito causados por conducir bajo sus efectos. Conclusiones: la situación actual sobre la accidentalidad vial muestra un preocupante aumento de la mortalidad, morbilidady discapacidad en países en vías de desarrollo como el nuestro. Se analizaron los efectos del alcohol,cocaína, canabinoides y metanfetaminas sobre el sistema nervioso central que disminuyen las habilidades del individuo para la conducción.

Alcohol consumption is acknowledged as an important cause of road accidents due to its depressing effect on the central nervous system. Although recreational or illegal drugs have a similar action little is known on their relation with road accidents. Objective: to determine the current situation in Colombia and worldwide on the effects of alcohol and illegal psychoactive substances on the central nervous system as possible causes of road accidents. Methods: a review of the literature following an online data base search using DeCS and MeSH terms: street drugs, designed drugs, ethanol, cocaine, cannabinoides, amphetamines, injuries, traffic accident and automobile driving. Results: particularly in the United States some trials report a close relationship between the use of psychoactive substances and road accidents rendering figures close to those of alcohol. This relation has also been demonstrated in Mexico. Most of the publications on road accident factors in Colombia do not differentiate alcohol consumption from psychoactive substances use. This reflects a lack of promotion and prevention programs on alcohol and substance-related risk when driving. Tests to determine their presence are not ordered in a routine manner and available data does not reflect the actual costs related to care provided to victims of accidents caused by driving under the influence of these substances. Conclusions: the current situation of road accidents shows a distressing increase in mortality, morbidity and disability rates in developing countries such as our country. The effects of alcohol, cocaine, cannabinoides and methamphetamines on the central nervous system were analyzed concluding they affect a person´s ability to drive safely.

Porous silicon-based rugate filters.

We report an experimental study of porous silicon-based rugate filters. We performed filter apodization, following a half-apodization approach, which successfully attenuated the sidelobes at both sides of the photonic stop band. We achieved successful reduction of interference ripples through the insertion of index-matching layers on the first and last interfaces. An apodized dielectric mirror and a rugate filter are compared: Appreciable differences in the harmonic presence and stop-band performance were observed and are commented on. Bandwidth control when index contrast is modified is also demonstrated. Finally, the possibility of combining different rugate filter designs to attain more complex responses is demonstrated by the achievement of a multi-stop-band filter. Numerical calculations for design optimization and comparison with experimental data are reported too.

La incisión vertical en cirugía torácica / The vertical incision in thoracic surgery

Se aboga en este trabajo por la técnica de toracotomía con incisión vertical áxilo-costal, mediante la cual se han realizado 16 operaciones con resultados satisfactorios, pues los pacientes no han presentado dolor torácico, complicación de la herida o limitación funcional. Se hace además, una descripción de esta técnica quirúrgica(AU)

La vaguectomía en el tratamiento quirúrgico de la úlcera duodenal

Los resultados obtenidos en los 5 años transcurridos son traidos a esta Jornada Nacional de Gastroenterología. Durante ese tiempo han sido sometidos a la vaguectomía 284 casos, de los cuales a 221 se les practicó como operación complementaria una piloroplastia y a 63 una antrectomía. Este trabajo se basa en el estudio de 238 pacientes que fueron los que respondieron a nuestra llamada(AU)