Trace gases detection by photoacoustic technique based on a lineal chirp excitation scheme

En este trabajo se presenta un nuevo esquema de medición para espectroscopía fotoacústica de gases traza basado en un esquema de excitación up-chirp. Esta forma combina las ventajas de los esquemas resonante y pulsado. Para mostrar el potencial de esta técnica se la comparó con un esquema de excitación resonante sobre la medición de muestras de dióxido de nitrógeno en aire contenidas en una resonador acústico de alumnio. Los resultados mostraron que la técnica chirp permite realizar mediciones de corta duración con muy buena relación señal a ruido.We present a new photoacoustic gas-trace measurement setup, based on a chirped optical chopper. This method combines features of the resonant and pulsed techniques. To show the advantages of this setup, we carried out a comparison with the resonant method in samples of NO2 contained in a one-dimensional acoustic resonator. The results show the chirped technique allows carrying out short-term acquisitions with good signal-to-noise ratio.Fil: Carreño Romano, Carlos Germán. Universidad de Buenos Aires. Facultad de Ingeniería; ArgentinaFil: Perez Fogwill, German A.. Universidad de Buenos Aires. Facultad de Ingeniería; ArgentinaFil: Santiago, G. D.. Universidad de Buenos Aires. Facultad de Ingeniería; ArgentinaFil: González, Martín Germán. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería; Argentin

Construcción de un aparato de flujo de calor radial para calcular la energía de interfase sólida-líquida en aleaciones ternarias

La energía de interfase sólida-líquida juega un papel muy importante en procesos de solidificación. Es la magnitud que gobierna la escala de tamaño en la morfología de la micro estructura en estos procesos. Para calcular la energía de interfase sólida-líquida en aleaciones binarias y ternarias, se construyó un aparato de flujo de calor radial tal como describe Gündüz [1]. Este aparato permite mantener un gradiente de temperatura muy estable durante largos períodos de tiempo y por ende es capaz de definir y mantener equilibrada termodinámicamente una interfase sólida-líquida con las fases sólida (fases _, _ y _ del sistema ternario Al-Cu-Ag en este caso) y líquida de una aleación. Después de un enfriamiento instantáneo, la probeta se puede analizar metalográficamente y la curvatura local de la frontera de grano es analizada. A partir de esta información y la determinación del enfriamiento local en el perfil de frontera de grano es posible evaluar la energía de interfase sólida-líquida. En esta investigación, el aparato de flujo de calor radial ha sido optimizado para producir por primera vez interfaces de las fases sólidas _, _ y _ su correspondiente fase líquida del sistema ternario Al-Cu-Ag

How does a cadaver model work for testing ultrasound diagnostic capability for rheumatic-like tendon damage?

To establish whether a cadaver model can serve as an effective surrogate for the detection of tendon damage characteristic of rheumatoid arthritis (RA). In addition, we evaluated intraobserver and interobserver agreement in the grading of RA-like tendon tears shown by US, as well as the concordance between the US findings and the surgically induced lesions in the cadaver model. RA-like tendon damage was surgically induced in the tibialis anterior tendon (TAT) and tibialis posterior tendon (TPT) of ten ankle/foot fresh-frozen cadaveric specimens. Of the 20 tendons examined, six were randomly assigned a surgically induced partial tear; six a complete tear; and eight left undamaged. Three rheumatologists, experts in musculoskeletal US, assessed from 1 to 5 the quality of US imaging of the cadaveric models on a Likert scale. Tendons were then categorized as having either no damage, (0); partial tear, (1); or complete tear (2). All 20 tendons were blindly and independently evaluated twice, over two rounds, by each of the three observers. Overall, technical performance was satisfactory for all items in the two rounds (all values over 2.9 in a Likert scale 1-5). Intraobserver and interobserver agreement for US grading of tendon damage was good (mean κ values 0.62 and 0.71, respectively), with greater reliability found in the TAT than the TPT. Concordance between US findings and experimental tendon lesions was acceptable (70-100 %), again greater for the TAT than for the TPT. A cadaver model with surgically created tendon damage can be useful in evaluating US metric properties of RA tendon lesions

Caracterización fisicoquímica de las aguas industriales generadas por la producción de almidón de yuca mediante el método de vía húmeda

The purpose of this study was to analyze the physical and chemical attributes of liquid waste produced during the extraction of cassava starch. The study focused on determining the levels of various contamination indicators, such as COD, BOD5, and SST. The wastewater from four rallanderias in the "La Balsa" area of the Calderón parish in the Portoviejo canton of Ecuador was sampled during the first half of 2022. The results from a mass balance calculation showed that only 3.06 m3 of residual water is discharged per day from processing 454 kg of starch. This volume of wastewater contains approximately 14 to 18 kg/day of pollutant load, and total cyanide concentrations ranged between 4 and 8 mg CN-/L.El objetivo principal de esta investigación fue identificar las características físicos-químicas de los efluentes líquidos que se generan durante la extracción de almidón de yuca a fin de conocer las concentraciones en las que se encuentran diversos parámetros indicadores de contaminación tales como DQO, DBO5, SST entre otros. Se realizaron muestreos a las aguas residuales de cuatro rallanderías del sitio “La Balsa” de la parroquia Calderón del cantón Portoviejo, Ecuador durante el primer semestre de 2022. Los resultados obtenidos de un balance de masa realizado permitieron conocer que solo en el procesamiento de 454 kg de almidón se descargan alrededor de 3.06 m3 de agua residual por día, determinando así que ese volumen de agua residual contiene aproximadamente de 14 a 18 kg/día de carga contaminante, se encontraron concentraciones de cianuro total que oscilaron entre 4 y 8 mg CN-/L

Conventional vs. tubeless percutaneous nephrolithotomy. Is the urinary diversion really necessary?

Introducción La nefrolitotomía percutánea (NLP) convencional utiliza derivación con nefrostomía para mejorar el drenaje de orina, facilitar la hemostasia postoperatoria y permitir un trayecto seguro para intervenciones adicionales futuras. Sin embargo, en los últimos años el procedimiento de NLP se ha modificado: ahora permite el retiro del uso del catéter de nefrostomía o de derivación urinaria, procedimiento conocido como tubeless. El presente estudio pretende evaluar la experiencia institucional en cuanto a seguridad, eficacia y ventajas de la NLP tubeless. Materiales y métodos Entre agosto de 2012 y mayo de 2014 se reclutó a 51 pacientes del Hospital Universitario San Ignacio y Clínica Fundadores para manejo con nefrolitotomía percutánea. Se incluyó a 49 pacientes con litiasis renal menor de 5cm de diámetro y mayor de 2cm con punción única o múltiple. Se aleatorizaron en 2 grupos: grupo A sin derivación (no nefrostomía no catéter doble J) 26 pacientes, grupo B con derivación (nefrostomía sonda Foley 18 Fr) 23 pacientes. Los desenlaces evaluados fueron: efectividad verificada mediante revisión de imágenes postoperatorias y definida como cálculo residual menor de 5mm, sangrado postoperatorio con medición de hemoglobina durante las primeras 24 h después de cirugía, valoración de dolor con escala visual análoga, necesidad de analgésicos durante las primeras 4 h, cantidad de rescates de analgésico durante las primeras 24 h de cirugía. Los datos se analizaron mediante el paquete estadístico IBM SPSS versión 20, utilizando estadística no paramétrica con la prueba de Wilcoxon Mann-Whitney una vez se determinó que la muestra no tenía una distribución normal. Las variables dicotómicas se analizaron utilizando la prueba de Chi2. Resultados Las características de base de los pacientes son comparables: la edad promedio en el grupo A fue de 44,73 años y en el B de 50,26 años (p=0,186), el peso en el grupo A fue de 75,96 kg y en el B de 71,96 kg (p=0,054), el tamaño de los cálculos en el A fue de 28,23mm en promedio y en el B de 29,69mm, sin diferencia estadísticamente significativa (p=0,517). No hubo diferencias significativas en cuanto a efectividad en ambos grupos: en el A el porcentaje de lito residual fue de 1,15% y en el B de 0,87% (p=0,713). No hubo diferencias estadísticamente significativas en cuanto a sangrado postoperatorio (p=0,566), pero sí se observó mayor dolor, requerimiento de analgésicos y mayor número de rescates en los pacientes a los cuales se les dejó derivación mediante nefrostomía. Discusión Nuestro trabajo demuestra que la NLP sin derivación urinaria es una técnica segura en aquellos pacientes en los cuales se logra una extracción completa del cálculo, con sangrado comparable a la cirugía convencional y, adicionalmente, con el beneficio de menor dolor y menor requerimiento de analgésico postoperatorio.Q4Artículo original5-9Introduction Conventional percutaneous nephrolithotomy (PNL) uses a nephrostomy derivation to improve the drainage of urine, facilitate postoperative hemostasis and allow a safe course for future additional surgical interventions. However, in recent years the PNL procedure has been modified to avoid the use of a nephrostomy catheter or any other urinary diversion. This procedure is known as tubeless. This study aims to assess the institutional experience in safety, efficiency and advantages of tubeless PNL. Materials and methods Between August 2012 and May 2014, 51 patients were recruited in San Ignacio University Hospital and Fundadores Clinic to be treated with PNL. Forty-nine patients with kidney lithiasis less than 5cm of diameter and greater than 2cm with single or multiple puncture were included. They were randomised into 2 groups: group A no derivation (no nephrostomy catheter, no double J) 26 patients, group B with derivation (18 Fr Foley nephrostomy catheter) 23 patients. The evaluated outcomes were: Effectiveness verified by reviewing postoperative images and defined as a residual stone less than 5mm of diameter, postoperative bleeding with hemoglobin measurement during the first 24h after surgery, pain assessment with the visual analog scale, need for analgesics during the first 4h, amount of analgesic rescues during the first 24h of surgery. Data were analyzed using the statistical package SPSS version 20, using the nonparametric statistical test Wilcoxon Mann-Whitney 11 it was determined that the sample does not have a normal distribution, the dichotomous variables were analyzed using Chi2 test. Results Baseline characteristics of patients are comparable: The average age in the group A was 44.73 and 50.26 years in the group B (P=.186), average weight in group A and B was 75.96kg and 71.96kg, respectively (P=.054), the average size of the stones in group A was 28.23mm and 29.69mm in group B with no statistically significant difference (P=.517). There were no significant differences in effectiveness in both groups, in group A the percentage of residual lithiasis was 1.15% and 0.87% in group B (P=.713). There were no statistically significant differences in postoperative bleeding (P=.566), although pain, analgesic requirement and number of rescues needed were greater in patients who were left with a nephrostomy derivation. Discussion Our work shows that percutaneous nephrolithotomy without urinary diversion is a safe procedure in patients in whom a complete stone removal is achieved, with bleeding comparable to conventional surgery, and additionally with the benefit of less pain and less postoperative analgesic requirement

Aerosol properties derived from ground-based Fourier transform spectra within the COllaborative Carbon Column Observing Network

Fourier transform infrared (FTIR) spectroscopy is particularly relevant for climate studies due to its ability to provide information on both fine absorption structures (i.e. trace gases) and broadband continuum signatures (i.e. aerosols or water continuum) across the entire infrared (IR) domain. In this context, this study assesses the capability of the portable and compact EM27/SUN spectrometer, used within the research infrastructure COCCON (COllaborative Carbon Column Observing Network), to retrieve spectral aerosol properties from low-resolution FTIR solar absorption spectra (0.5 cm−1). The study focuses on the retrieval of aerosol optical depth (AOD) and its spectral dependence in the 873–2314 nm spectral range from COCCON measurements at the subtropical high-mountain Izaña Observatory (IZO, Tenerife, Spain), which were coincidentally carried out with standard sun photometry within the Aerosol Robotic Network (AERONET) in the 3-year period from December 2019 to September 2022. The co-located AERONET–COCCON database was used to cross-validate these two independent techniques in the common spectral range (870–1640 nm), demonstrating an excellent agreement at the near-coincident spectral bands (mean AOD differences limited to 0.005, standard deviations up to 0.021 and Pearson regression coefficients up to 0.97). This indicates that the low-resolution COCCON instruments are suitable for detecting the aerosol broadband signal contained in the IR spectra in addition to the retrieval of precise trace gas concentrations, provided a robust calibration procedure (Langley-based or absolute calibration procedures) is used to compensate for the optical degradation of the external system (∼ 0.72 % per month). The study also assesses the capability of the EM27/SUN to simultaneously infer aerosols and trace gases and relate their common emission sources in two case study events: a volcanic plume from the La Palma eruption in 2021 and a nearby forest fire in Tenerife in 2022. Overall, our results demonstrate the potential of the portable low-resolution COCCON instruments to enhance the multi-parameter capability of the FTIR technique for atmospheric monitoring.</p

Quantification of CH4 emissions from waste disposal sites near the city of Madrid using ground- and space-based observations of COCCON, TROPOMI and IASI

We use different methane ground- and space-based remote sensing data sets for investigating the emission strength of three waste disposal sites close to Madrid. We present a method that uses wind-assigned anomalies for deriving emission strengths from satellite data and estimating their uncertainty to 9–14 %. The emission strengths estimated from the remote sensing data sets are significantly larger than the values published in the official register.ESA support through the COCCON-PROCEEDS and COCCON-PROCEEDS II projects. In addition, this research was funded by the Ministerio de Economía y Competitividad from Spain through the INMENSE project (CGL2016-80688-P). This research has largely benefit from funds of the Deutsche Forschungsgemeinschaft (provided for the two projects MOTIV and TEDDY with IDs/290612604 and 416767181, respectively)

Aerosol properties derived from ground-based Fourier transform spectra within the COllaborative Carbon Column Observing Network

Fourier transform infrared (FTIR) spectroscopy is particularly relevant for climate studies due to its ability to provide information on both fine absorption structures (i.e. trace gases) and broadband continuum signatures (i.e. aerosols or water continuum) across the entire infrared (IR) domain. In this context, this study assesses the capability of the portable and compact EM27/SUN spectrometer, used within the research infrastructure COCCON (COllaborative Carbon Column Observing Network), to retrieve spectral aerosol properties from low-resolution FTIR solar absorption spectra (0.5 cm$^{−1}$). The study focuses on the retrieval of aerosol optical depth (AOD) and its spectral dependence in the 873–2314 nm spectral range from COCCON measurements at the subtropical high-mountain Izaña Observatory (IZO, Tenerife, Spain), which were coincidentally carried out with standard sun photometry within the Aerosol Robotic Network (AERONET) in the 3-year period from December 2019 to September 2022. The co-located AERONET–COCCON database was used to cross-validate these two independent techniques in the common spectral range (870–1640 nm), demonstrating an excellent agreement at the near-coincident spectral bands (mean AOD differences limited to 0.005, standard deviations up to 0.021 and Pearson regression coefficients up to 0.97). This indicates that the low-resolution COCCON instruments are suitable for detecting the aerosol broadband signal contained in the IR spectra in addition to the retrieval of precise trace gas concentrations, provided a robust calibration procedure (Langley-based or absolute calibration procedures) is used to compensate for the optical degradation of the external system (∼ 0.72 % per month). The study also assesses the capability of the EM27/SUN to simultaneously infer aerosols and trace gases and relate their common emission sources in two case study events: a volcanic plume from the La Palma eruption in 2021 and a nearby forest fire in Tenerife in 2022. Overall, our results demonstrate the potential of the portable low-resolution COCCON instruments to enhance the multi-parameter capability of the FTIR technique for atmospheric monitoring

Petrography and application of the rietveld method to the quantitative analysis of phases of natural clinker generated by coal spontaneous combustion

Fine-grained and mainly reddish color, compact and slightly breccious and vesicular pyrometamorphic rocks (natural clinker) are associated to the spontaneous combustion of coal seams of the Cerrejón Formation exploited by Carbones del Cerrejón Limited in La Guajira Peninsula (Caribbean Region of Colombia). These rocks constitute remaining inorganic materials derived from claystones, mudstones and sandstones originally associated with the coal and are essentially a complex mixture of various amorphous and crystalline inorganic constituents. In this paper, a petrographic characterization of natural clinker, aswell as the application of the X-ray diffraction (Rietveld method) by mean of quantitative analysis of its mineral phases were carried out. The RIQAS program was used for the refinement of X ray powder diffraction profiles, analyzing the importance of using the correct isostructural models for each of the existing phases, which were obtained from the Inorganic Crystal Structure Database (ICSD). The results obtained in this investigation show that the Rietveld method can be used as a powerful tool in the quantitative analysis of phases in polycrystalline samples, which has been a traditional problem in geology

Simulation of mineral dust effects on UV radiation levels

The role played by aerosols on UV radiative transfer in the atmosphere is very uncertain. This is especially true regarding mineral dust. To determine the sensitivity of the UV levels to the presence of this atmospheric specie, we have simulated the UV irradiance with different vertical distributions of mineral dust. We have used a discrete ordinates radiative transfer model to obtain the UV levels both at sea level and at 3000 m. We have computed the aerosol single-scattering albedo, the phase function, and the asymmetry factor by Mie scattering theory. The background aerosol profiles were taken from WCRP [1986] models, whereas the radiative properties of mineral dust have been calculated from the aerosol size distribution obtained during Saharan dust invasions at Tenerife island (28.5°N, 16.3°W). The values for aerosol optical depth assumed as input for the model calculations are 0.2 (at 550 nm) for clean background aerosols and 0.3 (at 550 nm) for the mineral dust component. From the results we can conclude that the dust vertical size distribution can affect the irradiance ratio F (with Saharan dust)/F (no Saharan dust) by 2–4%. In addition, we observe that to the same total optical depth the diffuse UV levels depend not only on the vertical dust distribution but also on the background aerosol vertical distribution. We have computed differences for the diffuse radiation fluxes of about 5% between a maritime and a continental model to the same mineral dust vertical distribution.This work has been supported by the CICYT (Comisión Interministerial de Ciencia y Tecnologia- Spanish Government) under contract CLI97-0453 and the Gobierno Autónomo de Canarias by contract 4/95