106 research outputs found

    Visco-hyperelastic model with damage for simulating cyclic thermoplastic elastomers behavior applied to an industrial component

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    In this work a nonlinear phenomenological visco-hyperelastic model including damage consideration is developed to simulate the behavior of Santoprene 101-73 material. This type of elastomeric material is widely used in the automotive and aeronautic sectors, as it has multiple advantages. However, there are still challenges in properly analyzing the mechanical phenomena that these materials exhibit. To simulate this kind of material a lot of theories have been exposed, but none of them have been endorsed unanimously. In this paper, a new model is presented based on the literature, and on experimental data. The test samples were extracted from an air intake duct component of an automotive engine. Inelastic phenomena such as hyperelasticity, viscoelasticity and damage are considered singularly in this model, thus modifying and improving some relevant models found in the literature. Optimization algorithms were used to find out the model parameter values that lead to the best fit of the experimental curves from the tests. An adequate fitting was obtained for the experimental results of a cyclic uniaxial loading of Santoprene 101-73

    Soda-lime glass as biocompatible material to fabricate capillary-model devices by laser technologies

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    Microfluidic devices have been widely developed in the last decades because of the huge number of fields where they can be applied. Among all the different fabrication techniques available, laser direct writing stands out since it is a fast, accurate, versatile and non-contact method. It is particularly well-suited when working with glass, a robust and cost-efficient material. These laser advantages allow the direct fabrication of not only high quality single microchannel devices but also complex and bifurcated structures. This work establishes a roadmap for manufacturing capillary-model devices with good biocompability in soda-lime glass substrates with pulsed lasers operating in the nanosecond, picosecond and femtosecond temporal range. We determine the optimal laser parameters required for fabricating channels with a diameter:depth rate of 2:1, keeping a semi-circular section. The presence of tin doping (∼2%) in the soda-lime glass is shown to enable the fabrication with nanosecond pulses, and to improve the quality of the channels, reducing the cracking at the sides, when picosecond or femtosecond pulses were used. On the other hand, two regimes of surface roughness are found: a low roughness regime for channels fabricated with nanosecond lasers and a high roughness regime for those fabricated with pico and femtosecond lasers. Human umbilical vein endothelial cells (HUVEC) are employed for cell culturing for evaluating the biocompatibility of the channels. Structures manufactured with the nanosecond laser resulted more suitable in terms of cell adhesion than those fabricated with the picosecond and femtosecond lasers, due to the different surface roughness regimes obtained. In order to increase the biocompatibility of the channels fabricated with pico and femtosecond lasers and to improve the cell growth, a controlled post-thermal treatment is carried out for smoothing the surface

    Analysis by Finite Element Calculations of Light Scattering in Laser-textured AZO Films for PV thin-film Solar Cells

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    In the thin-film photovoltaic industry, to achieve a high light scattering in one or more of the cell interfaces is one of the strategies that allow an enhancement of light absorption inside the cell and, therefore, a better device behavior and efficiency. Although chemical etching is the standard method to texture surfaces for that scattering improvement, laser light has shown as a new way for texturizing different materials, maintaining a good control of the final topography with a unique, clean, and quite precise process. In this work AZO films with different texture parameters are fabricated. The typical parameters used to characterize them, as the root mean square roughness or the haze factor, are discussed and, for deeper understanding of the scattering mechanisms, the light behavior in the films is simulated using a finite element method code. This method gives information about the light intensity in each point of the system, allowing the precise characterization of the scattering behavior near the film surface, and it can be used as well to calculate a simulated haze factor that can be compared with experimental measurements. A discussion of the validation of the numerical code, based in a comprehensive comparison with experimental data is include

    A Guide for the Design of Benchmark Environments for Building Energy Optimization

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    The need for algorithms that optimize building energy consumption is usually motivated with the high energy consumption of buildings on a global scale. However, the current practice for evaluating the performance of such algorithms does not reflect this goal, as in most cases the performance is reported for one specific simulated building only, which provides no indication about the generalization of the score on other buildings. One approach to overcome this severe issue is to establish a shared collection of environments, each representing one simulated building setup, that would enable researchers to systematically compare and contrast the efficacy of their building optimization algorithms at scale. However, this requires that the individual environments are well designed for this goal. This paper is thus targeting the design of suitable environments for such a collection based on a detailed analysis of related publications that allows the identification of relevant characteristics for suitable environments. Based on this analysis a guide is developed that distills these characteristics into questions, intended to support a discussion of relevant topics during the design of such environments. Additional explanations and examples are provided for each question to make the guide more comprehensible. Finally, it is demonstrated how the guide can be applied, by utilizing it for the design of a novel environment, which represents an office building in tropical climate. This environment is released open source alongside this publication. We also indicate how test scenarios from existing publications could be enhanced to comply with the required characteristics according to our guide, underlining its importance for the future development and evaluation of building energy optimization algorithms, and thus for the sustainability of buildings in general

    Laser-Induced Crystallization of Sputtered Unhydrogenated Silicon at Low Temperatures

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    10-um-thick non-hydrogenated amorphous-silicon (a-Si) films were deposited at relatively high rates (_>10 Å/s) by radio-frequency magnetron sputtering (RFMS) on different large-area buffer-layer-coated glass substrates at deposition temperatures ranging from room temperature (RT) to 300oC. These amorphous samples were subsequently crystallized by means of a continuous-wave diode laser, looking for conditions to reach liquid-phase crystallization. The influence of deposition conditions on the quality of the final micro-crystalline silicon films has been studied

    Tumor-Infiltrating Lymphocytes in the Tumor Microenvironment of Laryngeal Squamous Cell Carcinoma:Systematic Review and Meta-Analysis

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    The presence of tumor-infiltrating lymphocytes (TIL) in the tumor microenvironment has been demonstrated to be of prognostic value in various cancers. In this systematic review and meta-analysis, we investigated the prognostic value of TIL in laryngeal squamous cell carcinoma (LSCC). We performed a systematic search in PubMed for publications that investigated the prognostic value of TIL in LSCC. A meta-analysis was performed including all studies assessing the association between TIL counts in hematoxylin-eosin (HE)-stained sections, for CD8+ and/or CD3+/CD4+ TIL and overall survival (OS) or disease-free survival (DFS). The pooled meta-analysis showed a favorable prognostic role for stromal TIL in HE sections for OS (HR 0.57, 95% CI 0.36-0.91, p = 0.02), and for DFS (HR 0.56, 95% CI 0.34-0.94, p = 0.03). High CD8+ TIL were associated with a prolonged OS (HR 0.62, 95% CI 0.4-0.97, p = 0.04) and DFS (HR 0.73, 95% CI 0.34-0.94, p = 0.002). High CD3+/CD4+ TIL demonstrated improved OS (HR 0.32, 95% CI 0.16-0.9, p = 0.03) and DFS (HR 0.23, 95% CI 0.10-0.53, p = 0.0005). This meta-analysis confirmed the favorable prognostic significance of TIL in LSCC. High stromal TIL evaluated in HE sections and intra-tumoral and stromal CD3+, CD4+ and/or CD8+ TIL might predict a better clinical outcome

    C/EBPβ Regulates TFAM Expression, Mitochondrial Function and Autophagy in Cellular Models of Parkinson’s Disease

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    Parkinson’s disease (PD) is a neurodegenerative disorder that results from the degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNpc). Since there are only symptomatic treatments available, new cellular and molecular targets involved in the onset and progression of this disease are needed to develop effective treatments. CCAAT/Enhancer Binding Protein β (C/EBPβ) transcription factor levels are altered in patients with a variety of neurodegenerative diseases, suggesting that it may be a good therapeutic target for the treatment of PD. A list of genes involved in PD that can be regulated by C/EBPβ was generated by the combination of genetic and in silico data, the mitochondrial transcription factor A (TFAM) being among them. In this paper, we observed that C/EBPβ overexpression increased TFAM promoter activity. However, downregulation of C/EBPβ in different PD/neuroinflammation cellular models produced an increase in TFAM levels, together with other mitochondrial markers. This led us to propose an accumulation of non-functional mitochondria possibly due to the alteration of their autophagic degradation in the absence of C/EBPβ. Then, we concluded that C/EBPβ is not only involved in harmful processes occurring in PD, such as inflammation, but is also implicated in mitochondrial function and autophagy in PD-like conditions.This research was supported by the “MINECO” (SAF2017-85199-P to A.P.C.), UCM-Santander (PR44/21-29931 to J.A.M.-G.) and the Health Institute “Carlos III” ( PI18/00118 to E.C. and PI21/00183 to F.B.). CIBERNED is funded by the Health Institute “Carlos III”. F.B. is a Miguel Servet Fellow (CP20/0007)

    Investigation on the structural changes of ZnO:Er:Yb thin film during laser annealing to fabricate a transparent conducting upconverter

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    A transparent and conducting ZnO:Er:Yb thin film with upconversion properties has been achieved after being annealed with continuous laser radiation just before the ablation point of the material. This work demonstrates that the laser energy preserves the conductivity of the film and at the same time creates an adequate surrounding for Er and Yb to produce visible upconversion at 660, 560, 520, and 480 nm under 980 nm laser excitation. The relation between the structural, electrical and upconversion properties is discussed. It is observed that the laser energy melts part of the material, which recrystallizes creating rare earth oxides and two different wurtzite structures, one with substitutional rare earths and oxygen vacancies (responsible for the conductivity) and the other without substitutional rare earth ions (responsible for the upconversion emission)

    Longitudinal interplay between subclinical atherosclerosis, cardiovascular risk factors, and cerebral glucose metabolism in midlife: results from the PESA prospective cohort study

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    BACKGROUND: Cardiovascular disease and dementia often coexist at advanced stages. Yet, longitudinal studies examining the interplay between atherosclerosis and its risk factors on brain health in midlife are scarce. We aimed to characterise the longitudinal associations between cerebral glucose metabolism, subclinical atherosclerosis, and cardiovascular risk factors in middle-aged asymptomatic individuals. METHODS: The Progression of Early Subclinical Atherosclerosis (PESA) study is a Spanish longitudinal observational cohort study of 4184 asymptomatic individuals aged 40-54 years (NCT01410318). Participants with subclinical atherosclerosis underwent longitudinal cerebral [18F]fluorodeoxyglucose ([18F]FDG)-PET, and annual percentage change in [18F]FDG uptake was assessed (primary outcome). Cardiovascular risk was quantified with SCORE2 and subclinical atherosclerosis with three-dimensional vascular ultrasound (exposures). Multivariate regression and linear mixed effects models were used to assess associations between outcomes and exposures. Additionally, blood-based biomarkers of neuropathology were quantified and mediation analyses were performed. Secondary analyses were corrected for multiple comparisons using the false discovery rate (FDR) approach. FINDINGS: This longitudinal study included a PESA subcohort of 370 participants (median age at baseline 49·8 years [IQR 46·1-52·2]; 309 [84%] men, 61 [16%] women; median follow-up 4·7 years [IQR 4·2-5·2]). Baseline scans took place between March 6, 2013, and Jan 21, 2015, and follow-up scans between Nov 24, 2017, and Aug 7, 2019. Persistent high risk of cardiovascular disease was associated with an accelerated decline of cortical [18F]FDG uptake compared with low risk (β=-0·008 [95% CI -0·013 to -0·002]; pFDR=0·040), with plasma neurofilament light chain, a marker of neurodegeneration, mediating this association by 20% (β=0·198 [0·008 to 0·740]; pFDR=0·050). Moreover, progression of subclinical carotid atherosclerosis was associated with an additional decline in [18F]FDG uptake in Alzheimer's disease brain regions, not explained by cardiovascular risk (β=-0·269 [95% CI -0·509 to -0·027]; p=0·029). INTERPRETATION: Middle-aged asymptomatic individuals with persistent high risk of cardiovascular disease and subclinical carotid atherosclerosis already present brain metabolic decline, suggesting that maintenance of cardiovascular health during midlife could contribute to reductions in neurodegenerative disease burden later in life. FUNDING: Spanish Ministry of Science and Innovation, Instituto de Salud Carlos III, Santander Bank, Pro-CNIC Foundation, BrightFocus Foundation, BBVA Foundation, "la Caixa" Foundation
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