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Heterodyne detection based on interband cascade lasers (ICL) has been demonstrated in a wide range of different applications. However, it is still often limited to bulky tabletop systems using individual components such as dual laser setups, beam shaping elements, and discrete detectors. In this work, a versatile integrated ICL platform is investigated for tackling this issue. A RF-optimized, two-section ICL approach is employed, consisting of a short section typically used for efficient modulation of the cavity field and a long gain section. Such a laser is operated in reversed mode, with the entire Fabry-Pérot waveguide utilized as a semiconductor optical amplifier (SOA) and the electrically separated short section as detector. Furthermore, a racetrack cavity is introduced as on-chip single-mode reference generator. The field of the racetrack cavity is coupled into the SOA waveguide via an 800â¯nm gap. By external injection of a single mode ICL operating at the appropriate wavelength, a heterodyne beating between the on-chip reference and the injected signal can be observed on the integrated detector section of the SOA-detector.
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Mid-infrared spectroscopy is a sensitive and selective technique for probing molecules in the gas or liquid phase. Investigating chemical reactions in bio-medical applications such as drug production is recently gaining particular interest. However, monitoring dynamic processes in liquids is commonly limited to bulky systems and thus requires time-consuming offline analytics. In this work, we show a next-generation, fully-integrated and robust chip-scale sensor for online measurements of molecule dynamics in a liquid solution. Our fingertip-sized device utilizes quantum cascade technology, combining the emitter, sensing section and detector on a single chip. This enables real-time measurements probing only microliter amounts of analyte in an in situ configuration. We demonstrate time-resolved device operation by analyzing temperature-induced conformational changes of the model protein bovine serum albumin in heavy water. Quantitative measurements reveal excellent performance characteristics in terms of sensor linearity, wide coverage of concentrations, extending from 0.075 mg ml-1 to 92 mg ml-1 and a 55-times higher absorbance than state-of-the-art bulky and offline reference systems.
Assuntos
Dispositivos Lab-On-A-Chip , Espectrofotometria Infravermelho , TemperaturaRESUMO
Mid-infrared attenuated total reflection (ATR) spectroscopy is a powerful tool for in situ monitoring of various processes. Mesoporous silica, an extensively studied material, has already been applied in sensing schemes due to its high surface area and tunable surface chemistry. However, its poor chemical stability in aqueous solutions at pH values higher than 8 and strong absorption below 1250 cm-1 limits its range of applications. To circumvent these problems, a mesoporous zirconia coating on ATR crystals was developed. Herein, the synthesis, surface modification, and characterization of ordered mesoporous zirconia films on Si wafers and Si-ATR crystals are presented. The modified coating was applied in sensing schemes using aromatic and aliphatic nitriles in aqueous solution as organic pollutants. The mesoporous zirconia coating shows strong chemical resistance when kept in alkaline solution for 72 h. The success of surface modification is confirmed using Fourier transform infrared (FT-IR) spectroscopy and contact angle measurements. Benzonitrile and valeronitrile in water are used as model analytes to evaluate the enrichment performance of the film. The experimental results are fitted using Freundlich isotherms, and enrichment factors of 162 and 26 are calculated for 10 mg L-1 benzonitrile and 25 mg L-1 valeronitrile in water, respectively. Limits of detection of 1 mg L-1 for benzonitrile and 11 mg L-1 for valeronitrile are obtained. The high chemical stability of this coating allows application in diverse fields such as catalysis with the possibility of in situ monitoring using FT-IR spectroscopy.
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RESUMEN Introducción: La empatía es el entendimiento adecuado del paciente, es considerada el eje central de la relación médico-paciente y es un componente vital para la atención en salud de alta calidad. Objetivo: Determinar los niveles de empatía hacia el paciente y su asociación con la funcionalidad familiar, estrés, rendimiento académico y factores sociodemográficos y académicos de los estudiantes de Medicina. Material y Métodos: Estudio observacional, transversal analítico. Se trabajó con todos los estudiantes de medicina (130), matriculados entre 3ro a 6to año, que cumplieron criterios de inclusión y exclusión. Las variables independientes fueron funcionalidad familiar, estrés y rendimiento académico. Se aplicó un cuestionario y la Escala de Empatía Médica de Jefferson versión S. En el análisis, se empleó la prueba de Shapiro-Wilk para evaluar la normalidad, se utilizaron estadísticos no paramétricos. Se consideró significancia estadística p<0,05. Resultados: La media de empatía global fue de 106,08 ± 18,29 puntos. Se encontraron diferencias estadísticamente significativas entre la media de empatía global con el sexo (p=0,03), el año de estudios (p=0,00), y la funcionalidad familiar (p=0,04). Conclusiones: El nivel de funcionamiento familiar está asociado con la empatía. Además, se encontró que las mujeres resultaron más empáticas y el mayor año académico estuvo asociado a una menor empatía hacia el paciente.
ABSTRACT Introduction: Empathy is the adequate understanding towards the patient; it is considered the central axis of the doctor-patient relationship and is a vital component for high-quality health care. Objective: To determine the levels of empathy towards the patient and their association with family functionality, stress, academic performance and sociodemographic and academic factors of medical students. Material and Methods: An observational, descriptive cross-sectional study was conducted. The study population included 130 medical students (between 3rd-year and 6-th year) who fulfilled the inclusion and exclusion criteria. The independent variables were family functionality, stress and academic performance. A questionnaire and the Jefferson Scale of Empathy Version S were applied. For the analysis, the Shapiro-Wilk test was used for testing the assumption of normality, the Student t Test and Anova test were used to establish the relationship between variables. Statistical significance of p <0.05 was considered. Results: The average global empathy was 106.08 ± 18.29 points. Statistically significant differences were found between global empathy and sex (p = 0.03), year of studies (p = 0.00), and family functionality (p = 0.04). Conclusions: The level of family functioning is associated with empathy. Moreover, it was also found that women were more empathic than men and higher academic years were associated with a lower level of empathy towards the patient.
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Workers in a production line for synchronous motors occasionally reported tingling sensations or a feeling of numbness in their hands when handling strong permanent magnets. As the magnetic flux density (B) and its gradients along and close to the surface of the permanent magnets were expected to be comparably high and the movements of the workers' hands may therefore cause relevant induction inside the tissue, a detailed dosimetric analysis of the in situ electric field inside the hands (Ei) of the workers was carried out. The time derivate of the magnetic flux density (dB/dt) occurring along the hands was determined based on time domain measurements using a specially developed 'measurement glove' containing 12 Hall sensors. Based on these measurement results temporal peak electric field strength (Ei) induced inside a newly developed high resolution anatomical hand models were numerically computed, using the scalar potential finite difference (SPFD) method. The highest measured dB/dt along the palmar side of the hand was 51.2 T s-1. The corresponding worst case temporal peak value of the maximum of the Ei averaged over 2 × 2 × 2 mm3 in soft tissue was 2.0 V m-1, which is a factor of 1.8 higher than the applicable exposure limit value, but still below the range of 3.8-6.2 V m-1 which is presently assumed the range of lowest stimulation threshold for peripheral nerves. Our analysis did therefore not provide an indication that the perception reported by the workers are due to tissue stimulation in the sense of provoking action potentials.
