Estimation of diesel-engined vehicle nitric oxide and soot emissions during the European light-duty Driving Cycle based on a transient mapping approach

151 σ.Η παρούσα διπλωματική εργασία ασχολείται με την εκτίμηση των εκπομπών των καυσαερίων που προέρχονται από οχήματα ελαφρού τύπου. Συγκεκριμένα οι ρύποι ως προς τους οποίους εξετάζεται ο κινητήρας του οχήματος είναι το μονοξείδιο του αζώτου (ΝΟ), η αιθάλη (soot) και το διοξείδιο του άνθρακα (C02). Η διαδικασία εκτίμησης των εκπομπών γίνεται κατά τη διάρκεια Μεταβατικού Κύκλου πόλης. Στην παρούσα μελέτη ο κινητήρας δοκιμάζεται κατά τη διάρκεια του Νεόυ Ευρωπαικού Κύκλου Οδήγησης (NEDC:New European Driving Cycle), ο οποίος χρησιμοποιείται για την πιστοποίηση των οχημάτων (επιβατικών και ελαφρών φορτηγών) που κυκλοφορούν στην Ευρωπαική Ένωση. Ο κύκλος διαρκεί 1180 δευτερόλεπτα και περιλαμβάνει ένα σύνολο σημείων ταχύτητας του οχήματος (σε km/h), τα οποία αντιπροσωπεύουν τις καθημερινές συνθήκες οδήγησης εντός και εκτός πόλης. Εφαρμόζοντας τον ψηφιοποιημένο χάρτη του κινητήρα, ο οποίος έχει προκύψει μέσα από πειραματικές μετρήσεις του κινητήρα στο εργαστήριο Μ.Ε.Κ. του Ε.Μ.Π. , προσομειώνεται με ένα απλό υπολογιστικό μοντέλο η συμπεριφορά του προκειμένου να εκτιμηθούν οι εκπεμπόμενοι ρύποι κατά τη διάρκεια του κύκλου (σε g/km).In this diploma thesis we apply a fast and relatively straightforward approach, in terms of cost and laboratory effort, to evaluation of the performance and emissions, including nitric oxide (NO) and soot, of a diesel-engined vehicle, during a light-duty transient cycle. The engine is tested during the NEDC: New European Driving Cycle which is used for light-duty vehicles certification in the European Union.The approach, which lies between simulation and experimentation, is based on a steady-state experimental mapping of the engine that was conducted in the Internal Combustion Engines laboratory of NTUA. Through this approach and the use of a simplified drivetrain model, the vehicle's emissions during the Cycle are estimated.Σωτήριος Χ. Λιούτα

Transient Photoinduced Absorption in Ultrathin As-grown Nanocrystalline Silicon Films

We have studied ultrafast carrier dynamics in nanocrystalline silicon films with thickness of a few nanometers where boundary-related states and quantum confinement play an important role. Transient non-degenerated photoinduced absorption measurements have been employed to investigate the effects of grain boundaries and quantum confinement on the relaxation dynamics of photogenerated carriers. An observed long initial rise of the photoinduced absorption for the thicker films agrees well with the existence of boundary-related states acting as fast traps. With decreasing the thickness of material, the relaxation dynamics become faster since the density of boundary-related states increases. Furthermore, probing with longer wavelengths we are able to time-resolve optical paths with faster relaxations. This fact is strongly correlated with probing in different points of the first Brillouin zone of the band structure of these materials

Microbleed Prevalence and Burden in Anticoagulant-Associated Intracerebral Bleed

Prior studies suggest an association between Vitamin K antagonists (VKA) and cerebral microbleeds (CMBs); less is known about nonvitamin K oral anticoagulants (NOACs). In this observational study we describe CMB profiles in a multicenter cohort of 89 anticoagulation-related intracerebral hemorrhage (ICH) patients. CMB prevalence was 51% (52% in VKA-ICH, 48% in NOAC-ICH). NOAC-ICH patients had lower median CMB count [2(IQR:1–3) vs. 7(4–11); P \u3c 0.001]; ≥5 CMBs were less prevalent in NOAC-ICH (4% vs. 31%, P = 0.006). This inverse association between NOAC exposure and high CMB count persisted in multivariable logistic regression models adjusting for potential confounders (OR 0.10, 95%CI: 0.01–0.83; P = 0.034)

Memristive and neuromorphic behavior in a Li x CoO 2 nanobattery

International audienceThe phenomenon of resistive switching (RS), which was initially linked to non-volatile resistive memory applications, has recently also been associated with the concept of memristors, whose adjustable multilevel resistance characteristics open up unforeseen perspectives in cognitive computing. Herein, we demonstrate that the resistance states of Li(x)CoO2 thin film-based metal-insulator-metal (MIM) solid-state cells can be tuned by sequential programming voltage pulses, and that these resistance states are dramatically dependent on the pulses input rate, hence emulating biological synapse plasticity. In addition, we identify the underlying electrochemical processes of RS in our MIM cells, which also reveal a nanobattery-like behavior, leading to the generation of electrical signals that bring an unprecedented new dimension to the connection between memristors and neuromorphic systems. Therefore, these LixCoO2-based MIM devices allow for a combination of possibilities, offering new perspectives of usage in nanoelectronics and bio-inspired neuromorphic circuits

Lateral electrical transport, optical properties and photocurrent measurements in two-dimensional arrays of silicon nanocrystals embedded in SiO2

In this study we investigate the electronic transport, the optical properties, and photocurrent in two-dimensional arrays of silicon nanocrystals (Si NCs) embedded in silicon dioxide, grown on quartz and having sizes in the range between less than 2 and 20 nm. Electronic transport is determined by the collective effect of Coulomb blockade gaps in the Si NCs. Absorption spectra show the well-known upshift of the energy bandgap with decreasing NC size. Photocurrent follows the absorption spectra confirming that it is composed of photo-generated carriers within the Si NCs. In films containing Si NCs with sizes less than 2 nm, strong quantum confinement and exciton localization are observed, resulting in light emission and absence of photocurrent. Our results show that Si NCs are useful building blocks of photovoltaic devices for use as better absorbers than bulk Si in the visible and ultraviolet spectral range. However, when strong quantum confinement effects come into play, carrier transport is significantly reduced due to strong exciton localization and Coulomb blockade effects, thus leading to limited photocurrent

The nucleoporin ALADIN regulates Aurora A localization to ensure robust mitotic spindle formation

The formation of the mitotic spindle is a complex process that requires massive cellular reorganization. Regulation by mitotic kinases controls this entire process. One of these mitotic controllers is Aurora A kinase, which is itself highly regulated. In this study, we show that the nuclear pore protein ALADIN is a novel spatial regulator of Aurora A. Without ALADIN, Aurora A spreads from centrosomes onto spindle microtubules, which affects the distribution of a subset of microtubule regulators and slows spindle assembly and chromosome alignment. ALADIN interacts with inactive Aurora A and is recruited to the spindle pole after Aurora A inhibition. Of interest, mutations in ALADIN cause triple A syndrome. We find that some of the mitotic phenotypes that we observe after ALADIN depletion also occur in cells from triple A syndrome patients, which raises the possibility that mitotic errors may underlie part of the etiology of this syndrome

Serum magnesium and calcium levels in relation to ischemic stroke : Mendelian randomization study

ObjectiveTo determine whether serum magnesium and calcium concentrations are causally associated with ischemic stroke or any of its subtypes using the mendelian randomization approach.MethodsAnalyses were conducted using summary statistics data for 13 single-nucleotide polymorphisms robustly associated with serum magnesium (n = 6) or serum calcium (n = 7) concentrations. The corresponding data for ischemic stroke were obtained from the MEGASTROKE consortium (34,217 cases and 404,630 noncases).ResultsIn standard mendelian randomization analysis, the odds ratios for each 0.1 mmol/L (about 1 SD) increase in genetically predicted serum magnesium concentrations were 0.78 (95% confidence interval [CI] 0.69-0.89; p = 1.3 7 10-4) for all ischemic stroke, 0.63 (95% CI 0.50-0.80; p = 1.6 7 10-4) for cardioembolic stroke, and 0.60 (95% CI 0.44-0.82; p = 0.001) for large artery stroke; there was no association with small vessel stroke (odds ratio 0.90, 95% CI 0.67-1.20; p = 0.46). Only the association with cardioembolic stroke was robust in sensitivity analyses. There was no association of genetically predicted serum calcium concentrations with all ischemic stroke (per 0.5 mg/dL [about 1 SD] increase in serum calcium: odds ratio 1.03, 95% CI 0.88-1.21) or with any subtype.ConclusionsThis study found that genetically higher serum magnesium concentrations are associated with a reduced risk of cardioembolic stroke but found no significant association of genetically higher serum calcium concentrations with any ischemic stroke subtype

Neuroimaging and clinical outcomes of oral anticoagulant-associated intracerebral hemorrhage

Objective Methods Whether intracerebral hemorrhage (ICH) associated with non-vitamin K antagonist oral anticoagulants (NOAC-ICH) has a better outcome compared to ICH associated with vitamin K antagonists (VKA-ICH) is uncertain. We performed a systematic review and individual patient data meta-analysis of cohort studies comparing clinical and radiological outcomes between NOAC-ICH and VKA-ICH patients. The primary outcome measure was 30-day all-cause mortality. All outcomes were assessed in multivariate regression analyses adjusted for age, sex, ICH location, and intraventricular hemorrhage extension. Results Interpretation We included 7 eligible studies comprising 219 NOAC-ICH and 831 VKA-ICH patients (mean age = 77 years, 52.5% females). The 30-day mortality was similar between NOAC-ICH and VKA-ICH (24.3% vs 26.5%; hazard ratio = 0.94, 95% confidence interval [CI] = 0.67-1.31). However, in multivariate analyses adjusting for potential confounders, NOAC-ICH was associated with lower admission National Institutes of Health Stroke Scale (NIHSS) score (linear regression coefficient = -2.83, 95% CI = -5.28 to -0.38), lower likelihood of severe stroke (NIHSS > 10 points) on admission (odds ratio [OR] = 0.50, 95% CI = 0.30-0.84), and smaller baseline hematoma volume (linear regression coefficient = -0.24, 95% CI = -0.47 to -0.16). The two groups did not differ in the likelihood of baseline hematoma volume <30cm(3) (OR = 1.14, 95% CI = 0.81-1.62), hematoma expansion (OR = 0.97, 95% CI = 0.63-1.48), in-hospital mortality (OR = 0.73, 95% CI = 0.49-1.11), functional status at discharge (common OR = 0.78, 95% CI = 0.57-1.07), or functional status at 3 months (common OR = 1.03, 95% CI = 0.75-1.43). Although functional outcome at discharge, 1 month, or 3 months was comparable after NOAC-ICH and VKA-ICH, patients with NOAC-ICH had smaller baseline hematoma volumes and less severe acute stroke syndromes. Ann Neurol 2018;84:702-712Peer reviewe