Thermal behavior of graphene oxide deposited on 3D-printed polylactic acid for photothermal therapy: an experimental–numerical analysis

The present work evaluates the thermal behavior of graphene oxide (GO) when deposited on 3D-printed polylactic acid (PLA), in order to develop a medical device for photothermal therapy applications. An experimental–numerical analysis was performed to assess the photothermal conversion capacity, based on the power emitted by a NIR (785 nm) laser, and the subsequent temperature distribution on the GO-PLA material. The influence of the deposited mass of GO and the PLA thickness was studied through 40 different scenarios. The results estimated a value of photothermal conversion efficiency of up to 32.6%, achieved for the lower laser power density that was tested (0.335 mW/mm²), and a high mass value of deposited GO (1.024 × 10−3 mg/mm²). In fact, an optimal mass of GO in the range of 1.024–2.048 × 10−3 mg/mm2 is proposed, in terms of absorption capacity, since a higher mass of GO would not increase the conversion efficiency. Moreover, the study allowed for an estimation of the thermal conductivity of this specific biomaterial (0.064 W/m·K), and proved that a proper combination of GO mass, PLA thickness, and laser power can induce ablative (>60 °C, in a concentrated area), moderate (50 °C), and mild (43 °C) hyperthermia on the bottom face of the biomaterial.Ministerio de Ciencia e Innovación | Ref. PID 2020-115415RB-100Xunta de Galicia | Ref. ED431C 2021/4

Numerical Modelling of Fouling Process in EGR System: A Review

In order to combat climate change, the new rigorous standards for pollutant reduction have shone a light on the use of exhaust gas recirculation system in order to minimize the NOx emissions of vehicles. For this reason, the fouling problem that appears on the exhaust gas recirculation line, caused by the deposition of soot particles and hydrocarbons that are part of the exhaust gas, has become particularly relevant in the last few years. In this field, researches have proposed numerical models in order to estimate and predict the deposit formation and growth. Using various numerical techniques, they intend to determine and reproduce the fouling layer buildup considering the different mechanisms that are involved in the deposit formation. This chapter provides a detailed and comprehensive account of the numerical approaches that have been proposed to analyze the fouling phenomenon that occurs inside the exhaust gas system. The main characteristics of each numerical model, as well as their main strengths and weaknesses, are exposed and evaluated, and their simulation capabilities are examined in detail

Analysis of the local growth and density evolution of soot deposits generated under hydrocarbon condensation: 3D simulation and detailed experimental validation

The utilization of the Exhaust Gas Recirculation (EGR) system during atypical engine operating conditions in order to meet future type-approval criteria exposes the internal surfaces of the devices to exhaust gas with elevated concentrations of particulate matter and greater amounts of hydrocarbon species, leading to the formation of dense and wet sludge deposits. To broaden the understanding of this phenomenon and contribute to the development of advanced EGR devices, this study presents an extended Computational Fluid Dynamics (CFD) model that, in addition to simulating the growth of fouling deposits caused by the accumulation of soot particles, also takes into account the condensation of hydrocarbons. Two scenarios with varying hydrocarbon concentrations in the exhaust flow are analysed, and the evolution of the deposit's thickness and density is determined. A sequential validation process is carried out by comparing the numerical results to actual deposit profiles at different stages of the fouling process. Additionally, hyperspectral images of the fouling layer have been acquired and analysed to validate the regions where hydrocarbon condensation is predicted to play a crucial role, enabling the verification of the hydrocarbon condensation phenomenon predicted by the numerical model. The results obtained under the studied conditions indicate that, on average, 77.4% of the analysed area exhibits a low level of relative error, demonstrating that the proposed model and the methodology used serve as a valuable tool for examining the propensity for deposit formation in devices subjected to fouling exacerbated by hydrocarbon condensation.Agencia Estatal de Investigación | Ref. PDC2021-121778-10

Sistemas fluidomecánicos no transporte: prácticas de simulacións numéricas

A tecnoloxía CFD, sigla de Computational Fluid Dynamics, en galego Dinámica de Fluídos Computacional, é unha técnica de análise numérica que permite determinar o comportamento dos fluídos mediante a realización de experimentos virtuais no ordenador. Esta técnica conta con varias décadas de desenvolvemento científico de respaldo, converténdose a día de hoxe nun dos estándares de análise para numerosos sectores industriais. É por iso que as simulacións numéricas son empregadas actualmente como eficaces ferramentas de diagnóstico nas etapas de deseño, mellora e optimización de produtos e procesos de fabricación en industrias como a naval, a automobilística, a aeroespacial, a hidráulica, as enerxías renovables, a enxeñería biomédica ou a construción. Co fin de achegar o emprego desta técnica ao alumnado do grado de Enxeñería Mecánica, este manual foi creado para servir de apoio á docencia da materia Sistemas fluidomecánicos e materiais avanzados para o transporte, enfocándose na aplicación práctica de simulacións numéricas en casos reais da enxeñería nos que se atopan involucrados fluxos de fluídos. Esta colección de exercicios prácticos pretende servir de axuda na etapa formativa do alumnado, facilitándolle a información necesaria e a metodoloxía que deberá empregar para levar a cabo o estudo de diferentes casos, e favorecendo así unha comprensión intuitiva dos problemas propostos mediante a análise dos resultados obtidos nas simulacións numéricas. Por tratarse dun dos programas de CFD máis empregados na industria, o software utilizado nas actividades deste manual é ANSYS Fluent 2020. Así tamén, as actividades propostas neste manual foron deseñadas para poder ser levadas a cabo contando cunhas esixencias computacionais accesibles para o alumnado, o cal poderá realizar nun tempo axeitado os exercicios aquí recollidos

Inhibition of ATG3 ameliorates liver steatosis by increasing mitochondrial function

Non-alcoholic fatty liver disease (NAFLD) is a major health threat in both developed and developing countries and is a precursor of the more advanced liver diseases, including non-alcoholic steatohepatitis (NASH), cirrhosis, and liver cancer. Currently, understanding the multiple and complex molecular pathways implicated in NAFLD onset and progression is a major priority. The transcription factor p63, which belongs to a family comprising p53, p63, and p73,1 is one of many factors that contributes to the development of liver steatosis. The role of p63 as a tumor suppressor and in cell maintenance and renewal is well studied, but we have recently reported that it is also relevant in the control of lipid metabolism.2 p63 encodes multiple isoforms that can be grouped into 2 categories; isoforms with an acidic transactivation domain (TA) and those without this domain (domain negative). The TAp63α isoform is elevated in the liver of animal models of NAFLD as well as in liver biopsies from obese patients with NAFLD. Furthermore, downregulation of p63α in the liver attenuates liver steatosis in diet-induced obese (DIO) mice, while the activation of TAp63α increases hepatic fat content, mediated by the activation of IKKβ and endoplasmic reticulum stress.2 A specialized form of autophagy that degrades lipid droplets, termed “lipophagy”, is a major pathway of lipid mobilization in hepatocytes. Lipophagy is elevated in hepatoma cells upon exposure to free fatty acids,3 and reduces the fatty acid load in mouse hepatocytes.4 Its impairment has been associated with the development of fatty liver and insulin resistance3,5; in contrast, the autophagic flux is increased during the activation of hepatic stellate cells.6 In the present study, we used an unbiased proteomics approach to gain insight into novel proteins modulating lipid metabolism in the liver of mice with genetic knockdown or overexpression of TAp63α. We found that autophagy-related gene 3 (ATG3) was upregulated by TAp63α activation and downregulated after p63α inhibition. ATG3 is elevated in several animal models of NAFLD and in the liver of patients with NAFLD. Genetic overexpression of ATG3 increased the lipid load in hepatocytes, while its repression alleviated TAp63α- and diet-induced steatosis. ATG3 exerted its role in lipid metabolism by regulating SIRT1 and mitochondrial function. Collectively, these findings identify ATG3 as a novel factor implicated in the development of steatosisThis work has been supported by grants from FEDER/Ministerio de Ciencia, Innovación y Universidades-Agencia Estatal de Investigación (PA: RTI2018-095134-B-100; DS and LH: SAF2017-83813-C3-1-R; MLMC: RTC2019-007125-1; CD: BFU2017-87721; ML: RTI2018–101840-B-I00; GS; PID2019-104399RB-I00; RN: RTI2018-099413-B-I00 and RED2018-102379-T; MLMC: SAF2017-87301-R; TCD: RTI2018-096759-A-100), FEDER/Instituto de Salud Carlos III (AGR: PI19/00123), Xunta de Galicia (ML: 2016-PG068; RN: 2015-CP080 and 2016-PG057), Fundación BBVA (RN, GS and MLM), Proyectos Investigación en Salud (MLMC: DTS20/00138), Sistema Universitario Vasco (PA: IT971-16); Fundación Atresmedia (ML and RN), Fundación La Caixa (M.L., R.N. and M.C.), Gilead Sciences International Research Scholars Program in Liver Disease (MVR), Marató TV3 Foundation (DS: 201627), Government of Catalonia (DS: 2017SGR278) and European Foundation for the Study of Diabetes (RN and GS). This research also received funding from the European Community’s H2020 Framework Programme (ERC Synergy Grant-2019-WATCH- 810331, to RN, VP and MS). Centro de Investigación Biomédica en Red (CIBER) de Fisiopatología de la Obesidad y Nutrición (CIBERobn), Centro de Investigación Biomédica en Red (CIBER) de Enfermedades Hepáticas y Digestivas (CIBERehd) and CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERdem). CIBERobn, CIBERehd and CIBERdem are initiatives of the Instituto de Salud Carlos III (ISCIII) of Spain which is supported by FEDER funds. We thank MINECO for the Severo Ochoa Excellence Accreditation to CIC bioGUNE (SEV-2016-0644)S

Impact of the first wave of the SARS-CoV-2 pandemic on the outcome of neurosurgical patients: A nationwide study in Spain

Objective To assess the effect of the first wave of the SARS-CoV-2 pandemic on the outcome of neurosurgical patients in Spain. Settings The initial flood of COVID-19 patients overwhelmed an unprepared healthcare system. Different measures were taken to deal with this overburden. The effect of these measures on neurosurgical patients, as well as the effect of COVID-19 itself, has not been thoroughly studied. Participants This was a multicentre, nationwide, observational retrospective study of patients who underwent any neurosurgical operation from March to July 2020. Interventions An exploratory factorial analysis was performed to select the most relevant variables of the sample. Primary and secondary outcome measures Univariate and multivariate analyses were performed to identify independent predictors of mortality and postoperative SARS-CoV-2 infection. Results Sixteen hospitals registered 1677 operated patients. The overall mortality was 6.4%, and 2.9% (44 patients) suffered a perioperative SARS-CoV-2 infection. Of those infections, 24 were diagnosed postoperatively. Age (OR 1.05), perioperative SARS-CoV-2 infection (OR 4.7), community COVID-19 incidence (cases/10 5 people/week) (OR 1.006), postoperative neurological worsening (OR 5.9), postoperative need for airway support (OR 5.38), ASA grade =3 (OR 2.5) and preoperative GCS 3-8 (OR 2.82) were independently associated with mortality. For SARS-CoV-2 postoperative infection, screening swab test <72 hours preoperatively (OR 0.76), community COVID-19 incidence (cases/10 5 people/week) (OR 1.011), preoperative cognitive impairment (OR 2.784), postoperative sepsis (OR 3.807) and an absence of postoperative complications (OR 0.188) were independently associated. Conclusions Perioperative SARS-CoV-2 infection in neurosurgical patients was associated with an increase in mortality by almost fivefold. Community COVID-19 incidence (cases/10 5 people/week) was a statistically independent predictor of mortality. Trial registration number CEIM 20/217

CFD transient simulation of the cough clearance process using an Eulerian wall film model

In this study, a cough cycle is reproduced using a computational methodology. The Eulerian wall film approach is proposed to simulate airway mucus flow during a cough. The reproduced airway domain is based on realistic geometry from the literature and captures the deformation of flexible tissue. To quantify the overall performance of this complex phenomenon, cough efficiency (CE) was calculated, which provided an easily reproducible measurement parameter for the cough clearance process. Moreover, the effect of mucus layer thickness was examined. The relationship between the CE and the mucus viscosity was quantified using reductions from 20 to 80%. Finally, predictions of CE values based on healthy person inputs were compared with values obtained from patients with different respiratory diseases, including chronic obstructive pulmonary disease (COPD) and respiratory muscle weakness (RMW). It was observed that CE was reduced by 50% in patients with COPD compared with that of a healthy person. On average, CE was reduced in patients with RMW to 10% of the average value of a healthy person

Development of an active contour based algorithm to perform the segmentation of soot agglomerates in uneven illumination TEM imaging

Automatic methods for morphological characterisation of nano-particulate from microscopy images usually involve the use of thresholding procedures, which cannot effectively deal with inhomogeneous backgrounds. In this paper, an algorithm based on an active contour model is proposed to extract soot projections from uneven illumination TEM imaging. The presented method involves a pre-processing stage where a median filter and a size normalisation step are performed. Then, the model applied is based on a level set formulation with local region fitting for noisy image segmentation. Once the active model reaches a convergence result, soot regions are isolated and labelled even under inhomogeneous illuminations. The accuracy of the proposed algorithm was evaluated by statistical comparisons of soot size descriptors extracted from 80 testing images, with results obtained by the application of the Otsu's segmentation method and manual measurements. Excellent agreement was found for uneven illumination micrographs without compromising the performance on regular imaging.Agencia Estatal de Investigación | Ref. ENE2017-87855-

An image-processing algorithm for morphological characterisation of soot agglomerates from TEM micrographs: Development and functional description

The inspection of soot agglomerates from microscopy images usually relies on manual human measurements, whereas image processing tools for faster analysis are highly demanded. In this study, an automated algorithm for the extraction of morphological soot descriptors from transmission electron micrographs is presented. The proposed algorithm involves the detection of the image scale (the conversion from pixels to nanometres) using a Hough transform and an optical character recognition process. Primary particles are identified through a two-step circle Hough transform combining phase-coding and edge-based approaches, whereas size descriptors are obtained through spatial and frequency filtering. Finally, the fractal dimension is obtained for each agglomerate as a projected-area derived measurement due to an iterative process. Results were validated by comparison of a set of micrographs taken at three different magnifications with manual image processing, obtaining p-values greater than 0.05 and around 91.5% time saving

Analysis of the local growth and density evolution of soot deposits generated under hydrocarbon condensation: 3D simulation and detailed experimental validation

The utilization of the Exhaust Gas Recirculation (EGR) system during atypical engine operating conditions in order to meet future type-approval criteria exposes the internal surfaces of the devices to exhaust gas with elevated concentrations of particulate matter and greater amounts of hydrocarbon species, leading to the formation of dense and wet sludge deposits. To broaden the understanding of this phenomenon and contribute to the development of advanced EGR devices, this study presents an extended Computational Fluid Dynamics (CFD) model that, in addition to simulating the growth of fouling deposits caused by the accumulation of soot particles, also takes into account the condensation of hydrocarbons. Two scenarios with varying hydrocarbon concentrations in the exhaust flow are analysed, and the evolution of the deposit's thickness and density is determined. A sequential validation process is carried out by comparing the numerical results to actual deposit profiles at different stages of the fouling process. Additionally, hyperspectral images of the fouling layer have been acquired and analysed to validate the regions where hydrocarbon condensation is predicted to play a crucial role, enabling the verification of the hydrocarbon condensation phenomenon predicted by the numerical model. The results obtained under the studied conditions indicate that, on average, 77.4% of the analysed area exhibits a low level of relative error, demonstrating that the proposed model and the methodology used serve as a valuable tool for examining the propensity for deposit formation in devices subjected to fouling exacerbated by hydrocarbon condensation