DISEÑO DE UN CIRCUITO DE CONTROL DE ILUMINACIÓN PARA UN SISTEMA FORMADOR DE IMÁGENES DE PURKINJE

ResumenLas imágenes de Purkinje son generadas por reflexión de la luz en las diferentes interfaces oculares (córnea anterior y posterior, y cristalino anterior y posterior). El estudio de estas imágenes es de suma importancia tanto en la optometría como en la oftalmología. En la UAM Azcapotzalco se ha desarrollado un sistema formador de imágenes de Purkinje, el cual permite generar y detectar dichas imágenes de indivuduos in-vivo. El sistema optoelectrónico presentado, consta de una iluminación infrarroja a 840nm, alimentada por un convertidor digital/analógico (current-steering DAC) con salida de corriente, el cual fue diseñado con transistores y multiplexores analógicos CMOS. El DAC entrega de 6.5 a 7.5 mA de corriente por LED en pasos de 0.25 mA (n bits de resolución), en las diferentes matrices. De este modo, las matrices funcionan apropiadamente sin saturarse, y por ende es posible generar las Imágenes de Purkinje sin reflexión y sin ruido de fondo, con lo cual se ha reducido el intervalo de la prueba (con tiempos de 10 a 15 minutos por sujeto).Palabras Claves: DAC de corriente, iluminación LED, imágenes de Purkinje, sistema ocular humano, tecnología CMOS. DESIGN OF A LIGHTING CONTROL CIRCUIT FOR A PURKINJE IMAGING SYSTEMAbstractPurkinje images are generated by the light reflection at different ocular interfaces (anterior and posterior cornea, anterior and posterior lens). The study of these images is of paramount importance in both optometry and ophthalmology. In UAM-Azcapotzalco, a Purkinje image-forming system has been developed, which allows the generation and detection of such images of in-vivo. The optoelectronic system presented, consists of an infrared illumination at 840nm, powered by a current-steering DAC with current output, which was designed with analogue CMOS transistors and multiplexers. The DAC delivers from 6.5 to 7.5 mA of current by LED in steps of 0.25 mA (n bits of resolution), in the different matrices. In this way, the matrices function properly without saturation, and therefore it is possible to generate the Purkinje Images without reflection and without background noise, which has reduced the interval of the test (with times of 10 to 15 minutes per subject).Keywords: Current DAC, human eye system CMOS technology, LED lighting, Purkinje images

Espectrofotometría del PET y PVC basado en Transmitancia

Actualmente los deshechos de polímeros son una de las principales fuentes de contaminación, causando daño ambiental y para el ser humano. Por ello existe la necesidad de contar con métodos eficientes de detección de los diferentes polímeros para su posterior separación y reciclaje. En este proyecto se presenta un estudio espectrofotométrico basado en transmitancia en un rango de 400 nm a 1000 nm con 4 diferentes fuentes de luz, una fuente halógena y tres fuentes monocromáticas centradas a 533.4 nm, 653.7 nm y 811 nm con la finalidad encontrar una fuente comercial capaz de diferenciar entre el Tereftalato de Polietileno (PET) y Policloruro de Vinilo (PVC) de manera eficiente y a bajo costo. Se encontró que el láser a 653.7 nm, proporciona una mayor distinción en la transmitancia de ambos materiales y que el espesor de ambos polímeros no influye en los resultados.Polymers are one of the main sources of contamination, causing environmental and health damages. Therefore, there is a need for efficient methods for detecting different polymers for subsequent separation and recycling. In this project a spectrophotometric study based on light transmission in a range of 400 nm to 1000 nm with four different light sources, a halogen source and three monochromatic sources focused at 533.4 nm, 653.7 nm and 811 nm, in order to find a commercial source for differentiating between polyethylene terephthalate (PET) and Polyvinyl Chloride (PVC) efficiently and at low cost. It was found that 653.7nm laser, provides a higher distinction in transmittance of both materials and the thickness of both polymers do not affect the results

Design, characterization and modeling of a tunneling break-down photodiode integrated in a standard 0.5ƒÝm CMOS technology

A low-voltage tunneling-breakdown photodiode has been designed, fabricated and characterized. Tests have been done to find dark-current, break-down voltage, turn on voltage, series and shunt resistance as well as spectral response. An average breakdown voltage of 1.1V states the device suitable for low-voltage circuits. After characterization, a model aimed for simulation in Spice was developed.Keywords: Photodetectors, Photodiodes, Solid state detectors

Tópicos selectos de ciencias químicas

La Química es una de las ramas de la ciencia que ha tomado mayor importancia en las últimas décadas. Es imposible no pensar en ella al escuchar los avances milagrosos de fármacos, materiales inteligentes, tecnología nanométrica, computadoras cuánticas o procesos catalíticos, donde la transformación controlada de la materia ha logrado la creación de sustancias con propiedades hechas a medida. En ese sentido, el papel de la Facultad de Química, en la formación de profesionales de dicha área, cobra una importancia superlativa; además del compromiso y la responsabilidad de formar sujetos no sólo con conocimiento, sino desarrollar su conciencia social y ecológica, indispensables para la situación actual y futura.Universidad Autónoma del Estado de México

Evaluation of a quality improvement intervention to reduce anastomotic leak following right colectomy (EAGLE): pragmatic, batched stepped-wedge, cluster-randomized trial in 64 countries

Background Anastomotic leak affects 8 per cent of patients after right colectomy with a 10-fold increased risk of postoperative death. The EAGLE study aimed to develop and test whether an international, standardized quality improvement intervention could reduce anastomotic leaks. Methods The internationally intended protocol, iteratively co-developed by a multistage Delphi process, comprised an online educational module introducing risk stratification, an intraoperative checklist, and harmonized surgical techniques. Clusters (hospital teams) were randomized to one of three arms with varied sequences of intervention/data collection by a derived stepped-wedge batch design (at least 18 hospital teams per batch). Patients were blinded to the study allocation. Low- and middle-income country enrolment was encouraged. The primary outcome (assessed by intention to treat) was anastomotic leak rate, and subgroup analyses by module completion (at least 80 per cent of surgeons, high engagement; less than 50 per cent, low engagement) were preplanned. Results A total 355 hospital teams registered, with 332 from 64 countries (39.2 per cent low and middle income) included in the final analysis. The online modules were completed by half of the surgeons (2143 of 4411). The primary analysis included 3039 of the 3268 patients recruited (206 patients had no anastomosis and 23 were lost to follow-up), with anastomotic leaks arising before and after the intervention in 10.1 and 9.6 per cent respectively (adjusted OR 0.87, 95 per cent c.i. 0.59 to 1.30; P = 0.498). The proportion of surgeons completing the educational modules was an influence: the leak rate decreased from 12.2 per cent (61 of 500) before intervention to 5.1 per cent (24 of 473) after intervention in high-engagement centres (adjusted OR 0.36, 0.20 to 0.64; P < 0.001), but this was not observed in low-engagement hospitals (8.3 per cent (59 of 714) and 13.8 per cent (61 of 443) respectively; adjusted OR 2.09, 1.31 to 3.31). Conclusion Completion of globally available digital training by engaged teams can alter anastomotic leak rates. Registration number: NCT04270721 (http://www.clinicaltrials.gov)