Stand-off LIBS in space exploration. New facility for the simulation of different planetary conditions

The availability of facilities capable of simulating extraterrestrial environments represents a need in today's planetary research to design, simulate and optimize those experiments carried out outside of Earth1,2. A thermal vacuum chamber (TVC) must be capable of operating under representative conditions (temperature, pressure, gas composition, radiation flux …) of space exploration targets and have a helpful volume compatible with the performing experiments and the testing of equipment under mimicked scenarios. Stand-off spectroscopies and connected techniques have gained a proper niche within the modern tools in situ compositional analysis for space exploration using rovers. The latest missions sent for space geo-exploration, e.g. NASA's Mars 2020 mission, show that Laser-Induced Breakdown Spectrometry (LIBS) is currently one of the key tools in understanding mineralogy and geochemistry of planetary surface. LIBS can obtain real-time information at distances up to 12 meters, together with other techniques such as RAMAN or VIS-IR spectroscopy3. The convenience of a TVC capable of performing stand-off spectroscopies under different analysis ranges allows reproducing the results obtained in Perseverance rover and for future missions, gaining insights about data treatment and data modelling, and anticipating experiments on Earth before the launch. This work presents the TVC available in the UMALASER lab and the stand-off LIBS experiments carried out at different atmospheric conditions up to 12m. Furthermore, the versatility of this camera in the field of stand-off analysis will be demonstrated by combining LIBS analysis with Laser-Induced Acoustics detections or other spectroscopic techniques (i.e. Raman). This array of remote analysis techniques has been applied for the compositional analysis of geological samples under Martian atmospheric conditions of pressure (8 mbar), composition (CO2 rich atmosphere) and air temperature (250 K).Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

LIBS-Acoustic Mid-Level Fusion Scheme for Mineral Differentiation under Terrestrial and Martian Atmospheric Conditions

The shockwave produced alongside the plasma during a laser-induced breakdown spectroscopy event can be recorded as an acoustic pressure wave to obtain information related to the physical traits of the inspected sample. In the present work, a mid-level fusion approach is developed using simultaneously recorded laser-induced breakdown spectroscopy (LIBS) and acoustic data to enhance the discrimination capabilities of different iron-based and calcium-based mineral phases, which exhibit nearly identical spectral features. To do so, the mid-level data fusion approach is applied concatenating the principal components analysis (PCA)-LIBS score values with the acoustic wave peak-to-peak amplitude and with the intraposition signal change, represented as the slope of the acoustic signal amplitude with respect to the laser shot. The discrimination hit rate of the mineral phases is obtained using linear discriminant analysis. Owing to the increasing interest for in situ applications of LIBS + acoustics information, samples are inspected in a remote experimental configuration and under two different atmospheric traits, Earth and Mars-like conditions, to validate the approach. Particularities conditioning the response of both strategies under each atmosphere are discussed to provide insight to better exploit the complex phenomena resulting in the collected signals. Results reported herein demonstrate for the first time that the characteristic sample input in the laser-produced acoustic wave can be used for the creation of a statistical descriptor to synergistically improve the capabilities of LIBS of differentiation of rocksFundings for this work were provided by the projects UMA18-FEDERJA-272 from the Junta de Andalucía and PID2020-119185GB-I00 from Ministerio de Ciencia e Innovación, Spain. P.P. is grateful to the Junta de Andalucía for his contract under the program Garantía Juvenil. Universidad de Málaga / CBUA"

Thermal Vision for Soil Assessment in a Multipurpose Environmental Chamber under Martian Conditions towards Robot Navigation

Soil assessment is important for mobile robot planning and navigation on natural and planetary environments. Terramechanic characteristics can be inferred from the thermal behaviour of soils under the influence of sunlight using remote sensors such as Long-Wave Infrared cameras. However, this behaviour is greatly affected by the low atmospheric pressures of planets such as Mars, so practical models are needed to relate robot remote sensing data on Earth to target planetary exploration conditions. This article proposes a general framework based on multipurpose environmental chambers to generate representative diurnal cycle dataset pairs that can be useful to relate the thermal behaviour of a soil on Earth to the corresponding behaviour under planetary pressure conditions using remote sensing. Furthermore, we present an application of the proposed framework to generate datasets using the UMA-Laserlab chamber, which can replicate the atmospheric \ch{CO2} composition of Mars. In particular, we analyze the thermal behaviour of four soil samples of different granularity by comparing replicated Martian surface conditions and their Earth's diurnal cycle equivalent. Results indicate a correlation between granularity and thermal inertia that is consistent with available Mars surface measurements recorded by rovers. The resulting dataset pairs, consisting of representative diurnal cycle thermal images with heater, air, and subsurface temperatures, have been made available for the scientific community.Comment: 10 pages, 13 figure

The sound of geological targets on Mars from the absolute intensity of laser-induced sparks shock waves

Inspection of geological material is one of the main goals of the Perseverance rover during its journey across the landscape of the Jezero crater in Mars. NASA's rover integrates SuperCam, an instrument capable of performing standoff characterization of samples using a variety of techniques. Among those tools, SuperCam can perform laser-induced breakdown spectroscopy (LIBS) studies to elucidate the chemical composition of the targets of interest. Data from optical spectroscopy can be supplemented by simultaneously-produced laser-produced plasma acoustics in order to expand the information acquired from the probed rocks thanks to the SuperCam's microphone (MIC) as it can be synchronized with the LIBS laser. Herein, we report cover results from LIBS and MIC during Perseverance's first 380 sols on the Martian surface. We study the correlation between both recorded signals, considering the main intrasample and environmental sources of variation for each technique, to understand their behavior and how they can be interpreted together towards complimenting LIBS with acoustics. We find that louder and more stable acoustic signals are recorded from rock with compact surfaces, i.e., low presence loose particulate material, and harder mineral phases in their composition. Reported results constitute the first description of the evolution of the intensity in the time domain of shockwaves from laser-produced plasmas on geological targets recorded in Mars. These signals are expected contain physicochemical signatures pertaining to the inspected sampling positions. As the dependence of the acoustic signal recorded on the sample composition, provided by LIBS, is unveiled, the sound from sparks become a powerful tool for the identification of mineral phases with similar optical emission spectra.Many people helped with this project in addition to the co-authors, including hardware and operation teams, and we are most grateful for their support. This project was supported in the USA by NASA’s Mars Exploration Program and in France is conducted under the authority of CNES. Research funded by projects UMA18-FEDERJA-272 from Junta de Andalucía and PID2020-119185GB-I00 from Ministerio de Ciencia e Innovacion, of Spain. P.P. is grateful to the European Union’s Next Generation EU (NGEU) plan and the Spanish Ministerio de Universidades for his Margarita Salas fellowship under the program ′′Ayudas para la Recualificacion del Sistema Universitario Español′′. RCW was funded by JPL contract 1681089. A.U was funded by NASA Mars 2020 Participating Scientist program 80NSSC21K0330. Funding for open access charge: Universidad de Málaga / CBU

Inter-Rater Variability in the Evaluation of Lung Ultrasound in Videos Acquired from COVID-19 Patients

12 páginas, 7 figuras, 1 tablaLung ultrasound (LUS) allows for the detection of a series of manifestations of COVID-19, such as B-lines and consolidations. The objective of this work was to study the inter-rater reliability (IRR) when detecting signs associated with COVID-19 in the LUS, as well as the performance of the test in a longitudinal or transverse orientation. Thirty-three physicians with advanced experience in LUS independently evaluated ultrasound videos previously acquired using the ULTRACOV system on 20 patients with confirmed COVID-19. For each patient, 24 videos of 3 s were acquired (using 12 positions with the probe in longitudinal and transverse orientations). The physicians had no information about the patients or other previous evaluations. The score assigned to each acquisition followed the convention applied in previous studies. A substantial IRR was found in the cases of normal LUS (κ = 0.74), with only a fair IRR for the presence of individual B-lines (κ = 0.36) and for confluent B-lines occupying 50% (κ = 0.50). No statistically significant differences between the longitudinal and transverse scans were found. The IRR for LUS of COVID-19 patients may benefit from more standardized clinical protocols.This research was partially funded by CDTI (Spanish acronym: Centre for Industrial Tech- nological Development), funding number COI-20201153. Partially supported by the Google Cloud Research Credits program with the funding number GCP19980904, by the project RTI2018-099118- A-I00 founded by MCIU/AEI/FEDER UE and by the European Commission–NextGenerationEU, through CSIC’s Global Health Platform (PTI Salud Global)

Desarrollo de instrumentación y metodologías innovadoras basadas en LIBS para el análisis de muestras geológicas y forenses

Tesis con mención internacionalEn el presente manuscrito de Tesis Doctoral, titulado “Desarrollo de instrumentación y metodologías innovadoras basadas en LIBS para el análisis de muestras geológicas y forenses”, se presenta el trabajo de investigación realizado durante los estudios predoctorales. Dicho trabajo fue supervisado por la Catedrática Nerea Bordel y el Prof. Titular Jorge Pisonero del Departamento de Física de la Universidad de Oviedo. El manuscrito de Tesis Doctoral está divido en 5 capítulos, además de tres secciones que describen los objetivos generales del trabajo realizado, un resumen de la Tesis Doctoral y las conclusiones finales derivadas de trabajo realizado. En el Capítulo 1 se realiza una breve introducción a los fundamentos y la instrumentación típica usada en espectroscopía, centrándose especialmente en aquellos aspectos más relacionados con LIBS (Laser-Induced Breakdown Spectroscopy). Además, se realiza una revisión sobre los fundamentos y el estado del arte de la técnica LIBS. En el Capítulo 2 se presenta una descripción de los diferentes pasos de montaje seguidos para obtener un sistema experimental LIBS, así como los estudios de caracterización realizados sobre el mismo. En el Capítulo 3 se expone la aplicación de nuevas metodologías relacionadas con LIBS para el análisis de muestras provenientes de diferentes actividades relacionadas con la minería. Inicialmente, se evaluó un método de cuantificación de metales pesados (Cu, Ni y Zn) en suelos provenientes de un área con antigua actividad de minería. Se estudió el proceso de preparación de muestra, y se realizó una optimización de diversos parámetros experimentales con el fin de realizar un estudio cuantitativo sobre la composición elemental de las muestras. Además, se investigaron diversas metodologías de tratamiento de los datos obtenidos (univariante y multivariante), encontrando que el uso del método IPLS es adecuado para predecir el contenido de metales en las muestras. En la segunda parte del Capítulo 3 se ha desarrollado una aplicación para la determinación de fluorita en mineral mediante LIBS; en colaboración con la empresa de minería Minersa. Se estudió la capacidad de LIBS para determinar la concentración de fluorita en diferentes etapas del proceso de concentración de mineral, además de la determinación de contaminantes minoritarios en el mismo. Este estudio se llevó a cabo mediante el uso de emisión elemental y molecular; en muestras de polvo y en pulpa, simulando las condiciones de la planta de concentración. En el Capítulo 4 se exponen los estudios realizados sobre la cuantificación de trazas de flúor en muestras solidas mediante LIBS. El análisis de flúor mediante LIBS no es sencillo debido a la baja eficiencia de emisión de este elemento en el rango espectral típico de LIBS (típicamente entre 200-1000 nm). El uso de la emisión molecular de CaF puede mejorar significativamente las capacidades para detectar trazas de flúor en muestras sólidas. Este capítulo describe la metodología para el análisis de flúor mediante la emisión molecular de estas bandas de CaF en muestras con presencia de calcio y sin calcio. En el primer caso, varias muestras con diferentes cantidades de F y Ca fueron analizados, optimizando diferentes paramentos como la relación molar óptima Ca:F, o las condiciones temporales de adquisición, obteniendo unas límites de detección de 50 µg/g, mejorando las capacidades analíticas encontradas en la bibliografía. En el caso de muestras sin Ca, se desarrolló una metodología para introducir dicho elemento mediante la nebulización de nitrito de calcio sobre la superficie de la muestra, obteniendo así señal molecular de CaF y unas capacidades analíticas comparables a las obtenidas en muestras con calcio. En el Capítulo 5, basado en una aplicación forense, se investigó el uso de LIBS para obtener el patrón de la distribución de residuos de disparo (GSR) mediante un mapeo químico con LIBS. Los GSR son partículas eyectadas durante un disparo de arma de fuego, que proporcionan información sobre la distancia de disparo estudiando el patrón que forman sobre el objetivo. La presencia simultánea de Sb, Pb y Ba es indicativa de la presencia de GSR. Varias muestras de tela se dispararon a diferentes distancias, estudiando en primer lugar la metodología de preparación de muestra, ya que las telas deben ser preservadas al considerarse muestras forenses. Tras la caracterización del espectro de los GSR provenientes de tres tipos de munición, se realizó un mapa LIBS en un área de 15 x 15 cm obteniendo la distribución elemental de Sb, Pb y Ba sobre las telas. Además, se comprobó que el método de preparación de muestra permite realizar re-análisis de una misma tela. Por último, se estudió la distribución de los elementos de interés sobre la tela, desarrollando una metodología para estimar la distancia de disparo mediante diversos tratamientos de datos, tanto univariante como multivariantes. Finalmente, se presentan las conclusiones finales derivadas de la Tesis, así como los artículos científicos derivados de la Tesis Doctoral

An exploratory study of the potential of LIBS for visualizing gunshot residue patterns

The study of gunshot residue (GSR) patterns can assist in the reconstruction of shooting incidences. Currently, there is a real need of methods capable of furnishing simultaneous elemental analysis with higher specificity for the GSR pattern visualization. Laser-Induced Breakdown Spectroscopy (LIBS) provides a multi-elemental analysis of the sample, requiring very small amounts of material and no sample preparation. Due to these advantages, this study aims at exploring the potential of LIBS imaging for the visualization of GSR patterns. After the spectral characterization of individual GSR particles, the distribution of Pb, Sb and Ba over clothing targets, shot from different distances, were measured in laser raster mode. In particular, an array of spots evenly spaced at 800 mum, using a stage displacement velocity of 4 mm/s and a laser frequency of 5 Hz was employed (e.g. an area of 130 × 165 mm2 was measured in less than 3 h). A LIBS set-up based on the simultaneous use of two spectrographs with iCCD cameras and a motorized stage was used. This set-up allows obtaining information from two different wavelength regions (258&-289 and 446&-463 nm) from the same laser induced plasma, enabling the simultaneous detection of the three characteristic elements (Pb, Sb, and Ba) of GSR particles from conventional ammunitions. The ability to visualize the 2D distribution GSR pattern by LIBS may have an important application in the forensic field, especially for the ballistics area.Ministerio de Economía y Competitividad (MINECO

Development and validation of a predictive model of in-hospital mortality in COVID-19 patients.

We retrospectively evaluated 2879 hospitalized COVID-19 patients from four hospitals to evaluate the ability of demographic data, medical history, and on-admission laboratory parameters to predict in-hospital mortality. Association of previously published risk factors (age, gender, arterial hypertension, diabetes mellitus, smoking habit, obesity, renal failure, cardiovascular/ pulmonary diseases, serum ferritin, lymphocyte count, APTT, PT, fibrinogen, D-dimer, and platelet count) with death was tested by a multivariate logistic regression, and a predictive model was created, with further validation in an independent sample. A total of 2070 hospitalized COVID-19 patients were finally included in the multivariable analysis. Age 61-70 years (p80 years (p2 ULN (p = 0.003; OR: 1.79; 95%CI: 1.22 to 2.62), and prolonged PT (p<0.001; OR: 2.18; 95%CI: 1.49 to 3.18) were independently associated with increased in-hospital mortality. A predictive model performed with these parameters showed an AUC of 0.81 in the development cohort (n = 1270) [sensitivity of 95.83%, specificity of 41.46%, negative predictive value of 98.01%, and positive predictive value of 24.85%]. These results were then validated in an independent data sample (n = 800). Our predictive model of in-hospital mortality of COVID-19 patients has been developed, calibrated and validated. The model (MRS-COVID) included age, male gender, and on-admission coagulopathy markers as positively correlated factors with fatal outcome