139 research outputs found

    Effect of crumb rubber gradation on a rubberized cold recycled mixture for road pavements

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    Cold recycling technique represents the most environmental friendly solution for pavement rehabilitation nowadays. In fact, this technique allows the use of the highest percentage of reclaimed asphalt avoiding the energy consumption related to aggregates heating required by the traditional hot mix asphalt design. The mix design represents a key phase of the cold mix production. The study of workability and compactability properties combined with a deep laboratory investigation is required. The idea of introducing crumb rubber in the cold mixtures was developed based on the concept of maximizing the valorization of recycled materials together with the goal of achieving high performance. In the present research project, two different gradations of crumb rubber, processed with the traditional grading method, have been adopted for the production of a cold recycled mixture stabilized with bitumen emulsion and cement. The spring-back effects of the rubber particles, which occur after compaction, together with the Indirect Tensile Strength and the Indirect Tensile Stiffness Modulus have been studied. The results show that the gradation of the adopted crumb rubber sensibly affects the compaction and mechanical properties of the cold recycled mixture

    Automatic Calibration of a Two-Axis Rotary Table for 3D Scanning Purposes

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    Rotary tables are often used to speed up the acquisition time during the 3D scanning of complex geometries. In order to avoid manual registration of the point clouds acquired with different orientations, automatic algorithms to compensate the rotation were developed. Alternatively, a proper calibration of the rotary axis with respect to the camera system is needed. Several methods are available in the literature, but they only consider a single-axis calibration. In this paper, a method for the simultaneous calibration of both axes of the table is proposed. A checkerboard is attached to the table, and several images with different poses are acquired. An optimization algorithm is then setup to determine the orientation and the locations of the two axes. A metric to assess the calibration quality was also defined by computing the average mean reprojection error. This metric is used to investigate the optimal number and distribution of the calibration poses, demonstrating that the optimum calibration results are achieved when a wider dispersion of the calibration poses is adopted

    Arene–Ruthenium(II) Acylpyrazolonato Complexes: Apoptosis-Promoting Effects on Human Cancer Cells

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    A series of ruthenium(II) arene complexes with the 4-(biphenyl-4-carbonyl)-3-methyl-1-phenyl-5-pyrazolonate ligand, and related 1,3,5-triaza-7-phosphaadamantane (PTA) derivatives, has been synthesized. The compounds have been characterized by NMR and IR spectroscopy, ESI mass spectrometry, elemental analysis, and X-ray crystallography. Antiproliferative activity in four human cancer cell lines was determined by MTT assay, yielding dose- and cancer cell line-dependent IC50 values of 9-34 ÎŒM for three hexamethylbenzene-ruthenium complexes, whereas the other metal complexes were much less active. Apoptosis was the mechanism involved in the anticancer activity of such compounds. In fact, the hexamethylbenzene-ruthenium complexes activated caspase activity, with consequent DNA fragmentation, accumulation of pro-apoptotic proteins (p27, p53, p89 PARP fragments), and the concomitant down-regulation of antiapoptotic protein Bcl-2. Biosensor-based binding studies indicated that the ancillary ligands were critical in determining the DNA binding affinities, and competition binding experiments further characterized the nature of the interaction

    Road Roughness Estimation Using Machine Learning

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    Road roughness is a very important road condition for the infrastructure, as the roughness affects both the safety and ride comfort of passengers. The roads deteriorate over time which means the road roughness must be continuously monitored in order to have an accurate understand of the condition of the road infrastructure. In this paper, we propose a machine learning pipeline for road roughness prediction using the vertical acceleration of the car and the car speed. We compared well-known supervised machine learning models such as linear regression, naive Bayes, k-nearest neighbor, random forest, support vector machine, and the multi-layer perceptron neural network. The models are trained on an optimally selected set of features computed in the temporal and statistical domain. The results demonstrate that machine learning methods can accurately predict road roughness, using the recordings of the cost approachable in-vehicle sensors installed in conventional passenger cars. Our findings demonstrate that the technology is well suited to meet future pavement condition monitoring, by enabling continuous monitoring of a wide road network

    Transient analysis and control of a Brayton heat pump during start-up

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    This paper aims to investigate the transient response of the DLR's CoBra prototype, an innovative Brayton-cycle heat pump intended to provide heat above 250 °C and currently under commissioning at the DLR facility in Cottbus, Germany. First, a comprehensive transient thermodynamic model of the system is developed, accounting for heat exchangers and piping thermal inertia. Furthermore, a control logic is presented that ensures safe operation throughout off-design conditions and start-up manoeuvres. In particular, several control parameters are considered to avoid potential operational issues, such as critical temperature gradients, compressor surge, and critical mechanical vibration phenomena due to resonance. The performed simulations aim to reduce start-up time and energy consumed during start-up. Results show that with the help of the described controller, the system can reach design operation via a transient trajectory safely and quickly. Therefore, the capability of the CoBra prototype to flexibly supply high-temperature heat is demonstrated

    Postcardiotomy Venoarterial Extracorporeal Membrane Oxygenation With and Without Intra-Aortic Balloon Pump

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    Publisher Copyright: © 2022 The Author(s)Objectives: To compare the outcomes of patients with postcardiotomy shock treated with venoarterial extracorporeal membrane oxygenation (VA-ECMO) only compared with VA-ECMO and intra-aortic balloon pump (IABP). Design: A retrospective multicenter registry study. Setting: At 19 cardiac surgery units. Participants: A total of 615 adult patients who required VA-ECMO from 2010 to 2018. The patients were divided into 2 groups depending on whether they received VA-ECMO only (ECMO only group) or VA-ECMO plus IABP (ECMO-IABP group). Measurements and Main Results: The overall series mean age was 63 +/- 13 years, and 33% were female. The ECMO-only group included 499 patients, and 116 patients were in the ECMO-IABP group. Urgent and/or emergent procedures were more common in the ECMO-only group. Central cannulation was performed in 47% (n = 54) in the ECMO-IABP group compared to 27% (n = 132) in the ECMO-only group. In the ECMOIABP group, 58% (n = 67) were successfully weaned from ECMO, compared to 46% (n = 231) in the ECMO-only group (p = 0.026). However, inhospital mortality was 63% in the ECMO-IABP group compared to 65% in the ECMO-only group (p = 0.66). Among 114 propensity score-matched pairs, ECMO-IABP group had comparable weaning rates (57% v 53%, p = 0.51) and in-hospital mortality (64% v 58%, p = 0.78). Conclusions: This multicenter study showed that adjunctive IABP did not translate into better outcomes in patients treated with VA-ECMO for postcardiotomy shock. (C) 2022 The Author(s). Published by Elsevier Inc.Peer reviewe

    Extracorporeal life support in mitral papillary muscle rupture: Outcome of multicenter study

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    Background: Post-acute myocardial infarction papillary muscle rupture (post-AMI PMR) may present variable clinical scenarios and degree of emergency due to result of cardiogenic shock. Veno-arterial extracorporeal life support (V-A ECLS) has been proposed to improve extremely poor pre- or postoperative conditions. Information in this respect is scarce.Methods: From the CAUTION (meChanical complicAtion of acUte myocardial infarcTion: an InternatiOnal multiceNter cohort study) database (16 different Centers, data from 2001 to 2018), we extracted adult patients who were surgically treated for post-AMI PMR and underwent pre- or/and postoperative V-A ECLS support. The end-points of this study were in-hospital survival and ECLS complications.Results: From a total of 214 post-AMI PMR patients submitted to surgery, V-A ECLS was instituted in 23 (11%) patients. The median age was 61.7 years (range 46-81 years). Preoperatively, ECLS was commenced in 10 patients (43.5%), whereas intra/postoperative in the remaining 13. The most common V-A ECLS indication was post-cardiotomy shock, followed by preoperative cardiogenic shock and cardiac arrest. The median duration of V-A ECLS was 4 days. V-A ECLS complications occurred in more than half of the patients. Overall, in-hospital mortality was 39.2% (9/23), compared to 22% (42/219) for the non-ECLS group.Conclusions: In post-AMI PMR patients, V-A ECLS was used in almost 10% of the patients either to promote bridge to surgery or as postoperative support. Further investigations are required to better evaluate a potential for increased use and its effects of V-A ECLS in such a context based on the still high perioperative mortality

    Central versus Peripheral Postcardiotomy Veno-Arterial Extracorporeal Membrane Oxygenation: Systematic Review and Individual Patient Data Meta-Analysis

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    Background: It is unclear whether peripheral arterial cannulation is superior to central arterial cannulation for postcardiotomy veno-arterial extracorporeal membrane oxygenation (VA-ECMO). Methods: A systematic review was conducted using PubMed, Scopus, and Google Scholar to identify studies on postcardiotomy VA-ECMO for the present individual patient data (IPD) meta-analysis. Analysis was performed according to the intention-to-treat principle. Results: The investigators of 10 studies agreed to participate in the present IPD meta-analysis. Overall, 1269 patients were included in the analysis. Crude rates of in-hospital mortality after central versus peripheral arterial cannulation for VA-ECMO were 70.7% vs. 63.7%, respectively (adjusted OR 1.38, 95% CI 1.08–1.75). Propensity score matching yielded 538 pairs of patients with balanced baseline characteristics and operative variables. Among these matched cohorts, central arterial cannulation VA-ECMO was associated with significantly higher in-hospital mortality compared to peripheral arterial cannulation VA-ECMO (64.5% vs. 70.8%, p = 0.027). These findings were confirmed by aggregate data meta-analysis, which showed that central arterial cannulation was associated with an increased risk of in-hospital mortality compared to peripheral arterial cannulation (OR 1.35, 95% CI 1.04–1.76, I2 21%). Conclusions: Among patients requiring postcardiotomy VA-ECMO, central arterial cannulation was associated with an increased risk of in-hospital mortality compared to peripheral arterial cannulation. This increased risk is of limited magnitude, and further studies are needed to confirm the present findings and to identify the mechanisms underlying the potential beneficial effects of peripheral VA-ECMO

    Outcome after Surgery for Iatrogenic Acute Type A Aortic Dissection

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    (1) Background: Acute Stanford type A aortic dissection (TAAD) may complicate the outcome of cardiovascular procedures. Data on the outcome after surgery for iatrogenic acute TAAD is scarce. (2) Methods: The European Registry of Type A Aortic Dissection (ERTAAD) is a multicenter, retrospective study including patients who underwent surgery for acute TAAD at 18 hospitals from eight European countries. The primary outcomes were in-hospital mortality and 5-year mortality. Twenty-seven secondary outcomes were evaluated. (3) Results: Out of 3902 consecutive patients who underwent surgery for acute TAAD, 103 (2.6%) had iatrogenic TAAD. Cardiac surgery (37.8%) and percutaneous coronary intervention (36.9%) were the most frequent causes leading to iatrogenic TAAD, followed by diagnostic coronary angiography (13.6%), transcatheter aortic valve replacement (10.7%) and peripheral endovascular procedure (1.0%). In hospital mortality was 20.5% after cardiac surgery, 31.6% after percutaneous coronary intervention, 42.9% after diagnostic coronary angiography, 45.5% after transcatheter aortic valve replacement and nihil after peripheral endovascular procedure (p = 0.092), with similar 5-year mortality between different subgroups of iatrogenic TAAD (p = 0.710). Among 102 propensity score matched pairs, in-hospital mortality was significantly higher among patients with iatrogenic TAAD (30.4% vs. 15.7%, p = 0.013) compared to those with spontaneous TAAD. This finding was likely related to higher risk of postoperative heart failure (35.3% vs. 10.8%, p < 0.0001) among iatrogenic TAAD patients. Five-year mortality was comparable between patients with iatrogenic and spontaneous TAAD (46.2% vs. 39.4%, p = 0.163). (4) Conclusions: Iatrogenic origin of acute TAAD is quite uncommon but carries a significantly increased risk of in-hospital mortality compared to spontaneous TAAD
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