1,254 research outputs found
Regener regenerating action of myofibrils through the application of medular monocytes (CMN) in muscle tissue altered by the action of Bisphenol A
El bisfenol-A (BPA) se ha descrito como un disruptor endocrino que perjudica la salud humana y animal. Como el BPA está presente en los alimentos y bebidas, debido a la lixiviación de los contenedores de policarbonato o latas de aluminio, los humanos están constantemente expuestos a él. Debido a la importancia para la salud pública de la exposición inconsciente al BPA, realizamos un estudio de su rápida acción sobre el tejido muscular y su posible tratamiento con monocitos de médula ósea. Para este propósito, 16 minipigs se distribuyeron aleatoriamente (n = 4) a uno de los siguientes grupos experimentales: el grupo de control tratado con BPA (durante 4 meses), el grupo de abstinencia de BPA (tratado durante 2 meses con BPA y dos meses sin), y el grupo de monocitos de médula ósea (MN) (tratado durante 2 meses con BPA, después de lo cual se retiró y el tratamiento con CMNs comenzó a durar 2 meses). Al final de los tratamientos, se realizó una biopsia de los músculos longissimus lumbaris (LL) y longissimus dorsis (LD). Las muestras fueron analizadas por microscopía óptica y electrónica. En nuestro estudio, se observó que después de la exposición continua al BPA aparecieron algunas alteraciones tanto en los músculos como en los colágenos de sus vainas. El grupo del que se retiró BPA durante dos meses exhibió una acción degenerativa reversible, con una recuperación parcial de los músculos y del colágeno. En el último grupo de estudio, evaluamos la acción de los monocitos de la médula ósea sobre el tejido muscular modificado, y observamos que presentaban una notable acción de recuperación ya que prácticamente todas las alteraciones leves de músculo y colágeno que habían aparecido se revirtieron.Bisphenol-A (BPA) has been described as an endocrine disruptor that impairs human and animal health. As BPA is present in food and drink, due to leaching from polycarbonate containers or aluminum cans, humans are constantly exposed to it. Due to the importance for public health of unconscious exposure to BPA, we conducted a study of its rapid action on muscle tissue and its possible treatment with bone marrow monocytes. For this purpose, 16 minipigs were randomly distributed (n = 4) to one of the following experimental groups: the control group treated with BPA (for 4 months), the BPA-withdrawal group (treated for 2 months with BPA and two months without), and the bone marrow monocytes (MN) group (treated for 2 months with BPA, after which it was withdrawn and CMNs treatment began lasting 2 months). At the end of the treatments, biopsy of the longissimus lumbaris (LL) and y longissimus dorsis (LD) was carried out. The samples were analysed by optical and electron microscopy. In our study, it was observed that after continuous exposure to BPA some alterations appeared both in the muscle bres and in the collagen bres of their sheaths. The group from which BPA was withdrawn for two months exhibited a reversible degenerative action, with a partial recovery of both the muscle and the collagen bres. In the last study group, we evaluated the action of the bone marrow monocytes on the modi ed muscle tissue, and observed that they presented a notable recovery action since practically all the muscle and collagen bre alterations which had appeared were reversed
An experimental study of process variables in turning operations of Ti 6Al 4V and Cr Co spherical prostheses
[EN] Ti 6Al 4V and Cr Co alloys are extensively used in manufacturing prostheses due to their biocompatibility, high strength-to-weight ratio and high resistance to corrosion and wear. However, machining operations involving Ti 6Al 4V and Cr Co alloys face a series of difficulties related to their low machinability which complicate the process of controlling the quality levels required in these parts. The main objective of this paper is to study the influence of cutting parameters, machine tool control accuracy and metrology procedures on surface roughness parameters and form errors in contouring operations of Ti 6Al 4V and Cr Co workpieces.
The machining performance of the two biocompatible materials is compared, focusing the study on part quality at low feed per revolution and the stochastic nature of plastic deformations at this regime. The results showed a better surface roughness control for Ti 6Al 4V, whereas for Cr Co alloys, the performance presents high variability.
In the case of form errors (sphericity), contouring errors and metrology procedures are important factors to be considered for quality assurance. In addition, the study analyses the correlation of the machining performance with different sensor signals acquired from a low cost non-intrusive multi-sensor, showing a high correlation of signals from acoustic emission sensors and accelerometers in the machining of spherical features on Ti 6Al 4V parts. The findings of this research work can be taken into account when designing prostheses components and planning their manufacturing processes.This work was partially supported by Fundacio Caixa-Castello Bancaixa under the research project INV-2009-39. The authors are grateful to Miguel Angel Aymerich and Arcadi Sanz, who assisted in the experimental part. The authors would also like to extend their acknowledgments to Lafitt Company for its collaboration. Additional support was provided by Tecnologico de Monterrey through the Research Chair in Mechatronics and Intelligent Machines.Abellán Nebot, JV.; Siller, H.; Vila, C.; Rodríguez, C. (2012). An experimental study of process variables in turning operations of Ti 6Al 4V and Cr Co spherical prostheses. International Journal of Advanced Manufacturing Technology. 63(9-12):887-902. doi:10.1007/s00170-012-3955-0S887902639-12Balazic M, Kopac J, Jackson MJ, Ahmed W (2007) Review: titanium and titanium alloy applications in medicine. Int J Nano Biomater 1:3–34Long M, Rack HJ (1998) Titanium alloys in total joint replacement—a materials science perspective. Biomaterials 19:1621–1639Ohkubo C, Watanabe I, Ford JP, Nakajima H, Hosoi T, Okabe T (2000) The machinability of cast titanium and Ti–6Al–4 V. Biomaterials 21:421–428Yang X, Liu CR (1999) Machining titanium and its alloys. Mater Sci Technol 3:107–139Barry J, Byrne G, Lennon D (2001) Observations on chip formation and acoustic emission in machining Ti–6Al–4 V alloy. Int J Mach Tools Manuf 41:1055–1070Ezugwu EO (2005) Key improvements in the machining of difficult-to-cut aerospace alloys. Int J Mach Tools Manuf 45:1353–1367Ezugwu EO, Da Silva RB, Bonney J, Machado AR (2005) Evaluation of the performance of CBN tools when turning Ti–6Al–4 V. Int J Mach Tools Manuf 45:1009–1014Aspinwall DK, Dewes RC, Mantle AL (2005) The machining of gamma-TiAl intermetallic alloys. CIRP Ann 54:99–104López de Lacalle LN, Pérez-Bilbatua J, Sánchez JA, Llorente JI, Gutierrez A, Albóniga J (2000) Using high pressure coolant in the drilling and turning of low machinability alloys. Int J Adv Manuf Technol 16:85–91Aydin AK (1991) Evaluation of finishing and polishing techniques on surface roughness of chromium–cobalt castings. J Prosthet Dent 65:763–767Xenodimitropoulou G, Radford DR (1998) The machining of cobalt–chromium alloy in partial denture. Int J Prosthodont 11(6):565–573Shi AJ (2008) Biomedical manufacturing: a new frontier of manufacturing research. J Manuf Sci Eng 130:021009-1-021009-8Grill A (2003) Diamond-like carbon coatings as biocompatible materials—an overview. Diamond Relat Mater 12:166–170Abellan-Nebot JV, Liu J, Subiron FR, Shi J (2011) State space modeling of variation propagation in multistage machining processes considering operation-induced variations. Submitted to ASME Transactions on Manufacturing Science and Engineering, in pressLiu J, Shi J, Hu SJ (2009) Quality assured setup planning based on the stream of variation model for multi-stage machining processes. IIE Trans, Qual Reliab Eng 41:323–334Camalaz M, Coupard D, Girot F (2008) A new material model for 2D numerical simulation of serrated chip formation when machining titanium alloy Ti–6Al–4 V. Int J Mach Tools Manuf 48:275–288Gadelmawla ES, Koura MM, Maksoud TMA, Elewa IM, Soliman HH (2002) Roughness parameters. J Mater Process Technol 123:133–145Stephenson DA, Agapiou JS (1997) Metal cutting theory and practice. Marcel Dekker, New YorkRamesh R, Mannan MA, Poo AN (2000) Error compensation in machine-tools—a review. Part I: geometric, cutting-force induced and fixture-dependent errors. Int J Mach Tools Manuf 40:1235–1256Ramesh R, Mannan MA, Poo AN (2000) Error compensation in machine-tools—a review. Part II: thermal errors. Int J Mach Tools Manuf 40:1257–1284López de Lacalle LN, Lamikiz A (2009) Machine-tools for high performance machining. Springer, LondonRamesh R, Mannan MA, Poo AN (2005) Tracking and contour error control in CNC servo systems. Int J Mach Tools Manuf 45:301–326Liang M, Mgwatu M, Zuo M (2001) Integration of cutting parameter selection and tool adjustment decisions for multipass turning. Int J Adv Manuf Technol 17:861–869Feng CXJ, Wang X (2002) Development of empirical models for surface roughness prediction in finish turning. Int J Adv Manuf Technol 20:348–356Benardos PG, Vosniakos GC (2003) Predicting surface roughness in machining: a review. Int J Mach Tools Manuf 43:833–844Schwenke H, Knapp W, Haitjema H, Weckenmann A, Schmitt R, Delbressine F (2008) Geometric error measurement and compensation of machines—an update. CIRP Ann 57:660–675Siller H, Rodriguez CA, Ahuett H (2006) Cycle time prediction in high-speed milling operations for sculptured surface finishing. J Mater Process Tech 174:355–362Liu K, Melkote SN (2006) Effect of plastic side flow on surface roughness in micro-turning processes. Int J Mach Tools Manuf 46:1778–1785Grzesik W (1996) A revised model for predicting surface roughness in turning. Wear 194:143–148Boothroyd G, Knight WA (1989) Fundamentals of machining and machine-tools. Marcel Dekker, New YorkBrammertz PH (1961) Die entstehung der oberflächenrauheit beim feindrehem. Industrie Anzeiger 2:25–32Gass SI, Witzgall C, Harary HH (1998) Fitting circles and spheres to coordinate measuring machine data. Int J Flex Manuf Syst 10:5–25The Brown & Sharpe DEA Mistral programming manual (2000)Montgomery D, Runger G (2007) Applied statistics and probability for engineers, 4th edn. Wiley, New Jersey, pp 273–277Buford A, Goswami T (2004) Review of wear mechanisms in hip implants: paper I—general. Mater Design 25:385–39
Portability study of Surface roughness models in milling
[EN] In spite of the huge number of research studies around empirical surface roughness models, there is no methodology applied in industry to model and adapt accurately the surface roughness in machining operations. Any change of the process with respect to the initial conditions where the experiments were conducted implies an additional estimation error which difficulties the use of the model in the current process. This paper studies the portability of empirical models for surface roughness prediction in face milling operations. As portability problem, we refer to how a proper surface roughness model obtained from theoretical/experimental data under specific conditions decreases its performance when it is applied in a different environment. The work gives some guidance for future design of more robust surface roughness models.Abellán-Nebot, J.; Bruscas, G.; Serrano, J.; Vila, C. (2017). Portability study of Surface roughness models in milling. Procedia Manufacturing. 13:593-600. doi:10.1016/j.promfg.2017.09.115S5936001
Análisis del uso racional de antihipertensivos en la región de Murcia
ResumenObjetivoEl objetivo del presente estudio ha sido conocer el patrón de uso de los fármacos antihipertensivos en la Región de Murcia, contrastando los resultados con los datos nacionales (patrón de referencia), pudiendo de esta manera detectar posibles puntos de mejora o establecer hipótesis para posteriores estudios.DiseñoEstudio farmacoepidemiológico (2004 a 2008), conforme a las recomendaciones de la OMS.EmplazamientoRegión de Murcia.ParticipantesCenso poblacional anual.Mediciones principalesEl uso de antihipertensivos se ha medido mediante el cálculo de la dosis diaria definida por mil habitantes-día (DHD).ResultadosLa utilización de antihipertensivos se ha incrementado significativamente de 196,6 DHD a 235,8 DHD. Los antihipertensivos más usados en 2008 eran los ARA-II (38,6%), seguido de los IECA (21,8%). Se ha producido un cambio de tendencia en el uso de los bloqueantes del sistema renina angiotensina (BSRA), con un incremento del 77,5% en los ARA-II y una disminución del 9,5% en los IECA. La comparación con los datos nacionales muestran un menor uso de antihipertensivos y un diferente patrón en la Región de Murcia.ConclusionesSe constata un menor uso de antihipertensivos respecto a España, por lo que podría haber infratratamiento de esta u otras enfermedades cardiovasculares en las que se usan estos fármacos en la Región de Murcia. Se observa un mayor uso de ARA-II, así como un menor uso de IECA. Las diferencias encontradas ponen de manifiesto la necesidad de realizar estudios encaminados a esclarecer sus causas, para lograr un uso más racional y eficiente de los antihipertensivos.AbstractObjectiveThe objective of this study was to determine the pattern of use of antihypertensive drugs in the Murcia Region, comparing the results with the national data, and detecting problems in order to make improvements, or establish hypotheses and to plan new studies.DesignPharmacoepidemiological study (from 2004 to 2008) in accordance with the recommendations from World Heath Organization.Setting: Murcia Region.ParticipansAnnual census of each year.Main measurementsThe use of antihypertensive drugs was measured by the daily doses per 1000 inhabitans-day (DHD).ResultsThe use of antihypertensive drugs has significantly increased from 196.6 DHD to 235.8 DHD. The antihypertensives more used at the end of 2008 were: angiotensin II receptor blockers–ARB- (38.6%) and angiotensin converting enzyme inhibitors–ACEI- (21.8%). There has been a tendency to change the use of rennin-angiotensin system blockers–RASB-, with an increase in ARB of 77.5% and and a decrease in ACEI 9.5%. The comparison with the national data shows qualitative and quantitative differences in the pattern of antihypertensive drugs used during the studied period.ConclusionsThe use of antihypertensive drugs in Murcia is less than in the rest of Spain. Therefore, this may be due to a problem of under treatment of this illness or other cardiovascular illnesses in the region. A greater use of ARB in Murcia and a lower use of ACEI was observed in Murcia. The differences found suggest that further studies are required to clarify their origins and causes, with the objective of achieving a more rational and efficient use of these drugs
Study of different cutting strategies for sustainable machining of hardened steels
This paper studies the power consumption of different cutting strategies in face milling operations in order to evaluate the efficiency of each cutting strategy. The experimental procedure evaluates the machine-tool efficiency by estimating cutting forces and measuring the power consumption. After modeling the efficiency of the machine-tool at different states (idle, fast movement and cutting at different conditions), the cutting strategies and cutting parameters are analyzed and compared in terms of sustainability (CO2 emissions) and quality (surface roughness). The optimal cutting strategy to ensure a predefined quality specification is also derived.Vila, C.; Abellán Nebot, JV.; Siller-Carrillo, HR. (2015). Study of different cutting strategies for sustainable machining of hardened steels. Procedia Engineering. 132:1120-1127. doi:10.1016/j.proeng.2015.12.604S1120112713
Multi-objective optimisation of product quality in the manufacture of Ti-6AI-4V prostheses
[EN] This paper presents a multi-objective optimisation procedure for optimising the quality of prostheses and manufacturing productivity. The aim of this procedure is to develop machining performance models through a minimal and progressive Design of Experiment (DoE), which models the variables of interest by linear regressions or Surface Response Models (SRMs). The multi-objective optimisation is based on desirability functions, which are defined according to the relative importance of each variable of interest. The procedure was implemented to optimise a process of manufacturing spherical turned components for Ti-6Al-4V hip prostheses with special requirements as regards surface roughness Ra, Rz and geometrical form toleranceThis work has been partially supported by Fundació Caixa-Castelló Bancaixa under the research project INV-2009-39. The authors are grateful to Miguel Angel Aymerich and Arcadi Sanz, who assisted in the experimental part. The authors extend their acknowledgements to Lafitt Company for its collaboration. Additional support was provided by Tecnológico de Monterrey through the research group in Mechatronics and Intelligent Machines.Abellán Nebot, JV.; Siller Carrillo, HR.; Vila, C.; Rodríguez González, CA. (2010). Multi-objective optimisation of product quality in the manufacture of Ti-6AI-4V prostheses. Journal of Manufacturing Technology Research. 5(3):353-369. https://doi.org/10.1504/IJMR.2010.033471S3533695
The Missing Link in the Magnetism of Hybrid Cobalt Layered Hydroxides: The Odd-Even Effect of the Organic Spacer
A dramatic change in the magnetic behaviour, which solely depends on the parity of the organic linker molecules, has been found in a family of layered Co-II hydroxides covalently functionalized with dicarboxylic molecules. These layered hybrid materials have been synthesized at room temperature using a one-pot procedure through the epoxide route. While hybrids connected by odd alkyl chains exhibit coercive fields (H-c) below ca. 3500 Oe and show spontaneous magnetization at temperatures (T-M) below 20 K, hybrids functionalized with even alkyl chains behave as hard magnets with H(c)5500 Oe and display a T-M higher than 55 K. This intriguing behaviour was studied by density functional theory with the incorporation of a Hubbard term (DFT+U) calculations, unveiling the structural subtleties underlying this observation. Indeed, the different molecular orientation exhibited by the even/odd alkyl chains, and the orientation of the covalently linked carboxylic groups modify the intensity of the magnetic coupling of both octahedral and tetrahedral in-plane sublattices, thus strongly affecting the magnetic properties of the hybrid. These findings offer an outstanding level of tuning in the molecular design of hybrid magnetic materials based on layered hydroxides
Special Wrestling Fitness Test: una prueba específica de lucha olímpica aplicada a luchadores jóvenes
The aim of this study was to perform a specific test of wrestling to assess physical condition of athletes and comparing physical performance test lab. To do an adaptation of Special Judo Fitness Test (SJFT) it was performed by developing a new specific exercise called Special Wrestling Fitness Test (SWFT). To diagnose the anaerobic capacity of the subjects we used the Wingate test of 30" lower body, while aerobic capacity was evaluated with the Yo-Yo test. Finally SWFT test was performed with the purpose of evaluating the physical capacity of the fighters. This study was conducted with 62 athletes in the Spanish national team wrestling in the ranks of junior and cadet.The wrestling has anaerobic has high resistance requirements, average power values recorded for this sample of 510,1 ± 134,2 W and reaching maximum values of 705,8 ± 166,9 W. During aerobic test covered a distance mean 911.6 ± 355.7 m VO2max estimated reaching 44.0 ± 2,9 ml / kg / min. In the case of the specific test of wrestling, parameters related to both anaerobic capacity as aerobic capacity, athletes got a SWFT index 16,37 ± 1,31. High levels of correlation was also reported between specific test results SWFT and anaerobic performance (r = -0,396; p = <0,01) and aerobic (r = 0,470; p = <0,01). These results indicate that this new test could be used to measure more specific and valid physical ability of the fighters, avoiding having to resort to laboratory tests whose gestures and energy demands away from the specificity of wrestling.El objetivo de este estudio fue llevar a cabo un test específico de lucha olímpica para evaluar la condición física de los deportistas y compararlas con test de rendimiento físico en laboratorio. Para ello se realizó una adaptación de Special Judo Fitness Test (SJFT), desarrollando un nuevo ejercicio especifico de lucha olímpica denominado Special Wrestling Fitness Test (SWFT). Para diagnosticar la capacidad anaeróbica de los sujetos utilizamos la prueba de Wingate de 30” de tren inferior, mientras que la capacidad aeróbica se evalúo con el Yo-Yo test. Por último se realizó la prueba de SWFT con el propósito de evaluar la capacidad física de los luchadores. Este estudio se llevo a cabo con 62 deportistas del equipo nacional español de lucha olímpica en las categorías inferiores de junior y cadete. La lucha olímpica tiene presenta elevados requerimientos de resistencia anaeróbica, registrándose valores de potencia media para esta muestra de 510,1 ± 134,2 W y llegando a valores máximos de 705,8 ± 166,9 W. Durante la prueba aeróbica recorrieron una distancia media de 911,6 ± 355,7 m y alcanzando un VO2máx estimado de 44,0 ± 2,9 ml/kg/min. En el caso de la prueba específica de lucha olímpica, relacionada tanto con parámetros de capacidad anaeróbica como con capacidad aeróbica, los deportistas consiguieron un índice SWFT de 16,37 ± 1,31. Se registraron igualmente elevados niveles de correlación entre los resultados del test específico SWFT y el rendimiento anaeróbico (r = -0,396; p = <0,01) y aeróbico (r = 0,470; p = <0,01). Estos resultados indican que este nuevo test podría ser utilizado para medir de forma más específica y válida la capacidad física de los luchadores, evitando tener que recurrir a pruebas de laboratorio cuyos gestos y demandas energéticas se alejan de la especificidad de la lucha olímpica
Effect of Yb concentration on the resistivity and lifetime of CdTe:Ge:Yb codoped crystals
The resistivity and electron lifetime of CdTe:Ge:Yb crystals are reported, demonstrating that the
effect of Yb concentration is crucial for accurate electrical compensation. It is also demonstrated
that the codoping of CdTe with Ge as deep donor and with Yb as rare-earth element could be a
promising way to obtain semiinsulating CdTe crystals with good transport properties. High
resistivity 5 10
9
cm and lifetime 9 s were obtained, thus confirming the beneficial effect of
rare-earth dopingThis work has been partly supported by the projects
CAM SENSORCDT S-0505/MAT/0209, CAM FOTOFLEX S-0505/ENE-123, and EU FP6 PHOLOGIC 017158. E.S.
also acknowledges the Spanish MEC for the fellowship FPU
2003-1388.Peer reviewe
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