Design, development and validation of a new laryngo-pharyngeal endoscopic esthesiometer and range-finder based on the assessment of air-pulse variability determinants

BACKGROUND: Laryngo-pharyngeal mechano-sensitivity (LPMS) is involved in dysphagia, sleep apnea, stroke, irritable larynx syndrome and cough hypersensitivity syndrome among other disorders. These conditions are associated with a wide range of airway reflex abnormalities. However, the current device for exploring LPMS is limited because it assesses only the laryngeal adductor reflex during fiber-optic endoscopic evaluations of swallowing and requires a high degree of expertise to obtain reliable results, introducing intrinsic expert variability and subjectivity. METHODS: We designed, developed and validated a new air-pulse laryngo-pharyngeal endoscopic esthesiometer with a built-in laser range-finder (LPEER) based on the evaluation and control of air-pulse variability determinants and on intrinsic observer variability and subjectivity determinants of the distance, angle and site of stimulus impact. The LPEER was designed to be capable of delivering precise and accurate stimuli with a wide range of intensities that can explore most laryngo-pharyngeal reflexes. RESULTS: We initially explored the potential factors affecting the reliability of LPMS tests and included these factors in a multiple linear regression model. The following factors significantly affected the precision and accuracy of the test (P < 0.001): the tube conducting the air-pulses, the supply pressure of the system, the duration of the air-pulses, and the distance and angle between the end of the tube conducting the air-pulses and the site of impact. To control all of these factors, an LPEER consisting of an air-pulse generator and an endoscopic laser range-finder was designed and manufactured. We assessed the precision and accuracy of the LPEER's stimulus and range-finder according to the coefficient of variation (CV) and by looking at the differences between the measured properties and the desired values, and we performed a pilot validation on ten human subjects. The air-pulses and range-finder exhibited good precision and accuracy (CV < 0.06), with differences between the desired and measured properties at <3 % and a range-finder measurement error of <1 mm. The tests in patients demonstrated obtainable and reproducible thresholds for the laryngeal adductor, cough and gag reflexes. CONCLUSIONS: The new LPEER was capable of delivering precise and accurate stimuli for exploring laryngo-pharyngeal reflexes

Bronchoscopist's perception of the quality of the single-use bronchoscope (Ambu aScope4™) in selected bronchoscopies: a multicenter study in 21 Spanish pulmonology services

Background: The disposable bronchoscope is an excellent alternative to face the problem of SARS-CoV-2 and other cross infections, but the bronchoscopist’s perception of its quality has not been evaluated. Methods: To evaluate the quality of the Ambu-aScope4 disposable bronchoscope, we carried out a cross-sectional study in 21 Spanish pulmonology services. We use a standardized questionnaire completed by the bronchoscopists at the end of each bronchoscopy. The variables were described with absolute and relative frequencies, measures of cen‑ tral tendency and dispersion depending on their nature. The existence of learning curves was evaluated by CUSUM analysis. Results: The most frequent indications in 300 included bronchoscopies was bronchial aspiration in 69.3% and the median duration of these was 9.1 min. The route of entry was nasal in 47.2% and oral in 34.1%. The average score for ease of use, image, and aspiration quality was 80/100. All the planned techniques were performed in 94.9% and the bronchoscopist was satisfed in 96.6% of the bronchoscopies. They highlighted the portability and immediacy of the aScope4TM to start the procedure in 99.3%, the possibility of taking and storing images in 99.3%. The CUSUM analysis showed average scores>70/100 from the frst procedure and from the 9th procedure more than 80% of the scores exceeded the 80/100 score

Iván D Exploring Strategies for Reducing High Intake Temperature Requirements and Allowing Optimal Operational Conditions in a Biogas Fueled HCCI Engine for Power Generation

This paper evaluates strategies for reducing the intake temperature requirement for igniting biogas in homogeneous charge compression ignition (HCCI) engines. The HCCI combustion is a promising technology for stationary power generation using renewable fuels in combustion engines. Combustion of biogas in HCCI engines allows high thermal efficiency similar to diesel engines, with low net CO 2 and low NO x emissions. However, in order to ensure the occurrence of autoignition in purely biogas fueled HCCI engines, a high inlet temperature is needed. This paper presents experimental and numerical results. First, the experimental analysis on a 4 cylinder, 1.9 L Volkswagen TDI diesel engine running with biogas in the HCCI mode shows high gross indicated mean effective pressure (close to 8 bar), high gross indicated efficiency (close to 45%) and NO x emissions below the 2010 US limit (0.27 g/kWh). Stable HCCI operation is experimentally demonstrated with a biogas composition of 60% CH 4 and 40% CO 2 on a volumetric basis, inlet pressures of 2-2.2 bar (absolute), and inlet temperatures of 200-210 C for equivalence ratios between 0.19-0.29. At lower equivalence ratios, slight changes in the inlet pressure and temperature caused large changes in cycle-to-cycle variations, while at higher equivalence ratios these same small pressure and temperature variations caused large changes to the ringing intensity. Second, numerical simulations have been carried out to evaluate the effectiveness of high boost pressures and high compression ratios for reducing the inlet temperature requirements while attaining safe operation and high power output. The one zone model in Chemkin was used to evaluate the ignition timing and peak cylinder pressures with variations in temperatures at intake valve close (IVC) from 373 to 473 K. In-cylinder temperature profiles between IVC and ignition were computed using Fluent 6.3 and fed into the multizone model in Chemkin to study combustion parameters. According to the numerical results, the use of both higher boost pressures and higher compression ratios permit lower inlet temperatures within the safe limits experimentally observed and allow higher power output. However, the range of inlet temperatures allowing safe and efficient operation using these strategies is very narrow, and precise inlet temperature control is needed to ensure the best results

Reactivity and Structural Changes of Coal during Its Combustion in a Low-Oxygen Environment

The aim of this study is to improve the understanding of phenomena that occur when a solid carbonaceous material is burned in a high temperature with a low-oxygen-content (<10%, v/v) environment similar to that found in the moderate and intense low-oxygen dilution (MILD) combustion. The morphology, reactivity, and physicochemical properties of partially reacted coal samples extracted from an environment emulating MILD combustion conditions were investigated through different analytical techniques, including elemental and thermogravimetric analyses, scanning electron microscopy, surface area, and Raman spectroscopy. The early stage of coal burnout was characterized by some changes in the organic constituents of coal because the low-molecular-weight compounds react quickly and are the first to be removed. After the devolatilization process under low oxygen combustion, an increase in surface area and porosity was observed simultaneously with a reduction in carbonaceous material reactivity as a result of the gradual increase of crystalline order and structural rearrangement of the carbonaceous network, making it more resistant to oxidation, as evidenced by Raman spectroscopy. The low reactivity of the carbonaceous material during the last stage of heterogeneous oxidation could explain the high level of unburned carbon that can be found in combustion systems that use flue gas recirculation, as occurs in MILD combustion

Evolutionary instability of the major histocompatibility complex class I loci in New World primates

Homologues of the human major histocompatibility complex (MHC) HLA-A , -B , -E , -F , and -G loci are present in all the Catarrhini (Old World primates, apes, and humans), and some of their allelic lineages have survived several speciation events. Analysis of 26 MHC class I cDNAs from seven different genera of New World primates revealed that the Callitrichinae (tamarins and marmosets) are an exception to these rules of MHC stability. In gene trees of primate MHC class I genes, sequences from the Callitrichinae cluster in a genus-specific fashion, whereas in the other genera of New World primates, as in the Catarrhini, they cluster in a transgeneric way. The genus-specific clustering of the Callitrichinae cDNAs indicates that there is no orthology between MHC class I loci in genera of this phyletic group. Additionally, the Callitrichinae genera exhibit limited variability of their MHC class I genes, in contrast to the high variability displayed by all other primates. Each Callitrichinae genus, therefore, expresses its own set of MHC class I genes, suggesting that an unusually high rate of turnover of loci occurs in this subfamily. The limited variability of MHC class I genes in the Callitrichinae is likely the result of the recent origin of these loci

Optimización de la operación de motores duales en el piso térmico Colombiano

IP 1115-405-20267En este proyecto se pretende introducir la sobrealimentación en la admisión y el enriquecimiento de aire con oxigeno, como mecanismos de atenuación de los efectos de pérdida de eficiencia y potencia, al convertir un MEC en modo dual es una tecnología ampliamente utilizada a nivel mundial, como estrategia para disminuir la dependencia de los combustibles fósiles. En un MEC dual se modifica el sistema de admisión para introducir una mezcla aire-combustible gaseoso, la cual es encendida al final de la carrera de compresión por una inyección piloto de diesel

Análisis numérico de recirculación interna en un tubo radiante sin encendido

Este artículo presenta un análisis numérico sobre los efectos que se generar utilizando tubos radiantes con recirculación interna de los productos de combustión con una cámara de pre-combustión. Este análisis se desarrolló con ayuda de un software comercial de CFD, Fluent (versión 6.3.26). Los resultados numéricos se validan con un montaje experimental basado en la desviación de la temperatura de salida de los gases. Estas desviaciones equivalen a menos del 5% y se atribuyen principalmente a la deficiencia de aislamiento en la superficie re-radiante. Para encontrar el efecto de recirculación en este tubo, se analizan las variaciones en los resultados considerando la misma característica de funcionamiento pero con diferentes anchos de ventana de recirculación, y particularmente una sin ventanas. A través de este estudio, fue posible observar la poca incidencia de los efectos de recirculación cuando la combustión no se desarrolla internamente en el tubo, particularmente en la temperatura sobre la superficie uniformemente en el tubo externo y la energía emitida, pero por otro lado se observa una leve disminución en la caída de presión del sistema.This paper presents a numerical analysis using the CFD Fluent (6.3.26 version) program to identify the effects that can be generated when using radiant tubes with internal recirculation of combustion products, but with a pre-combustion chamber. The numerical results are validated with an experimental assembly based on the outlet deviation of gases temperature. These deviations were less than 5 % and are attributed principality to isolation deficiency in the re-radiant surface. To independently find the recirculation effect in this tube, the same operational characteristic in the tube were maintained and an analysis using different windows recirculation widths as well as one without windows was done. Through this analysis, it was possible to observe the little importance of recirculation effects when combustion doesn’t occur internally in the tube on the uniformity surface temperature on the external tube and the emitted energy, but it decrease the system pressure drop slightly although its magnitude order is very small