Novel hybrid materials based on graphene:synthesis and characterization

Poreuze materialen zijn nodig voor vele toepassingen: het scheiden van gassen of vloeistoffen vereisen zeven waarbij moleculen van een bepaalde grootte kunnen passeren, terwijl anderen te groot zijn en achter blijven; een poreus oxide netwerk vangt de metalen deeltjes op in de katalysator van onze auto’s; poriën in vaste vormen zijn een goed opslagmedium voor een explosieve brandstof zoals waterstof. Omdat moleculen afmetingen hebben op de nanometer schaal moeten poriën ook deze afmetingen hebben. Als men nieuwe types van dergelijke poreuze netwerken wilt ontwikkelen en de mogelijke bestandsdelen overweegt, dan realiseert men dat carbon een bijzonder geschikte kandidaat is omdat het een licht element is, overvloedig aanwezig is op onze aarde in de vorm van grafiet en het geen problemen oplevert voor recycling. Grafiet is een stapel van vellen koolstof genaamd grafeen en kan worden omgezet in een nanoporeus materiaal als men erin slaagt om de vellen te scheiden door pilaren in de vorm van moleculen of aggregaten van atomen in de gewenste grootte. In dit proefschrift project maakten en manipuleerden we dergelijke nieuwe pillared materialen op basis van grafeen. We hebben geleerd om grafiet te scheiden in afzonderlijke grafeenvellen zonder deze te beschadigen door sonicatie in een organisch oplosmiddel. We zijn er ook in geslaagd om de individuele vellen te decoreren met functionele groepen die op hun beurt als ankers dienen voor bepaalde moleculen. Bovendien ontwikkelden wij een nieuwe manier om eerst de tussenlaagruimte van grafiet te openen door het plaatsen van salpeterzuur moleculen, zodat de daaropvolgende intercalatie van grotere moleculen wordt vergemakkelijkt

Match demands, players´ Characteristics and neuromuscular performance across the season in elite futsal players.

Futsal, also known as five-a-side indoor soccer, is a team-sport that is becoming increasingly popular in the last year. In fact, the number of futsal-related investigations is growing in recent years. The current thesis aimed to describe and explore the match demands, players¿ characteristics, and the neuromuscular performance across the season in futsal. The results of the present compendium of articles allowed concluding that futsal players are exposed to high physiological, neuromuscular, and biochemical stress during, immediately after, and post 24 h following the game, with significant differences on match demands between halves, but not considering contextual factors. Furthermore, official futsal matches presented higher intensity when compared to non-official matches. Regarding players¿ characteristics, professional futsal players cover greater distance, perform more high-intensity actions, and present lower standing time when compared to semi-professional players; moreover, the former present low percentages of body fat, high physiological and neuromuscular (i.e., sprinting, strength, and change of direction) capacities, and superior performance in the eccentric metrics of the countermovement jump (CMJ). Virtually all strength and conditioning coaches report monitoring training load, most of them through the use of subjective tools, utilize the neuromuscular and strength measurements to evaluate performance and monitor fatigue, and practice strength training and recovery strategies for the physical preparation in futsal. Elite futsal players presented significant positive changes in CMJ jump landing phases following the pre-season, however, concentric peak power in CMJ decreased significantly during the competitive season, and lastly, neuromuscular performance (i.e., sprint, horizontal jump, and CMJ kinetic variables), body composition, and relative number of non-contact injuries were significantly negative affected by detraining period derived from COVID-19 lockdown.Actividad Física y Deport

Μελέτη του υποβάθρου υψηλής ακτινοβολίας κατά την ομαδοποίηση ιχνών μιονίων στους ανιχνευτές Micromegas στον New Small Wheel του πειράματος ATLAS στο CERN

Η ακριβής ανακατασκευή των τροχιών φορτισμένων σωματιδίων, όπως μιονίων που παράγονται κατά τις συγκρούσεις πρωτονίου-πρωτονίου, αποτελεί κύριο συστατικό σχεδόν οποιασδήποτε μέτρησης πραγματοποιείται κατά τη λειτουργία του ανιχνευτή ATLAS (A Toroidal Large Hadron Collider Apparatus), από διαδικασίες του Καθιερωμένου Προτύπου, μετρήσεις ακριβείας, μέχρι και αναζητήσεις για νέα φυσικά φαινόμενα. Μια σημαντική αναβάθμιση κατά την χρονική περίοδο λήψης δεδομένων του Run 3 προς την κατεύθυνση της διατήρησης μιας εξαιρετικής ακρίβειας στον προσδιορισμό των τροχιών των μιονίων στους αυξημένους ρυθμούς παραγωγής σωματιδίων του Υψηλής Φωτεινότητας Μεγάλου Αδρονικού Επιταχυντή (High-Luminosity LHC, HL-LHC), ήταν η αντικατάσταση του εσώτερου “καπακιού" (end-cap) του κυλίνδρου του Φασματομέτρου Μιονίων (Muon Spectrometer, MS) από τον Νέο Μικρό Τροχό (New Small Wheel, NSW). Παρόλα αυτά, αποτελεί σύνηθες φαινόμενο τα μιόνια με υψηλή εγκάρσια ορμή να υφίστανται απώλειες ενέργειας με τη μορφή ακτινοβολίας. Οι απώλειες αυτές δημιουργούν εναποθέσεις ενέργειας (“χτυπήματα") κοντά στην τροχιά του μιονίου και “αλλοιώνουν" το σχήμα των συστοιχιών ιχνών μιονίων (clusters) στον NSW, με αποτέλεσμα να οδηγούν σε συστηματικά σφάλματα στην ανακατασκευή της θέσης αυτών των ομαδοποιημένων ιχνών μιονίων. Αρχικά, στην παρούσα εργασία θα εξεταστούν διάφορες μεταβλητές και παράμετροι που βασίζονται σε τρία δείγματα προσομοίωσης διαφορετικών εγκάρσιων ορμών, από ανακατασκευασμένες τροχιές μιονίων στα ανιχνευτικά “στρώματα" των ανιχνευτών Micromegas (Micro-mesh gaseous detectors) του NSW. Τελικός στόχος είναι η πραγματοποίηση μιας στατιστικής ανάλυσης ταξινόμησης για κάθε δείγμα προκειμένου να ελεγχθεί σε ποιόν βαθμό μπορούμε να ταυτοποιήσουμε τις ομάδες ιχνών από μιόνια που έχουν υποστεί απώλειες ενέργειας λόγω ακτινοβολίας, σε μια προσπάθεια να διαχωρίσουμε αυτό που θα ορίσουμε ως σήμα (cluster signal) από αυτό που θα ορίσουμε ως υπόβαθρο (cluster background).The precise reconstruction of the trajectories of charged particles like muons created in proton–proton (pp) collisions is a key ingredient in almost every measurement performed using the ATLAS (A Toroidal Large Hadron Collider Apparatus) detector, from Standard Model processes, precision measurements, up to searches for new physics phenomena. A significant upgrade during the Run 3 data taking period, in the direction of maintaining an excellent muon track resolution at the increased particle rates expected from the High-Luminosity LHC (HL-LHC), was the replacement of the innermost end-cap of the ATLAS Muon Spectrometer by the New Small Wheel (NSW). Nevertheless, it is a common occurence that muons with high transverse momentum undergo radiative energy losses. Those losses may produce energy deposits (hits) near the muon track and 'spoil' the shape of the groups of hits called clusters in the NSW, thus leading to a bias in the reconstructed cluster position. The initial objective of this work is to examine different variables and parameters based on Monte Carlo simulation samples of different transverse momentum of reconstructed muon tracks from the Micro-Mesh Gaseous (Micromegas) detector layers of the NSW. Final goal is to carry out a classification statistical analysis for each sample in order to check whether we can identify clusters from muons with radiative energy losses, in an attempt to discriminate what we will define as cluster signal and what we will define as cluster background

Υποστήριξη και αυτοματοποίηση λειτουργιών υπολογιστικού συστήματος στοχαστικής προσομοίωσης βιολογικών δικτύων μεγάλης κλίμακας

Σκοπός της πτυχιακής αυτής εργασίας ήταν η αυτοματοποίηση βασικών λειτουργιών συντήρησης του πρωτότυπου πιλοτικού συστήματος StochSoCs που αναπτύχθηκε στο Πανεπιστήμιο Αθηνών και το οποίο συνδυάζει λογισμικό με υλικό ειδικού σκοπού (FPGA Systems on Chip) για την παράλληλη στοχαστική προσομοίωση βιολογικών δικτύων μεγάλης κλίμακας, με χιλιάδες αλληλεπιδράσεις ανάμεσα στα εμπλεκόμενα βιομόρια. Κύριος στόχος ήταν η μείωση του χρόνου που απαιτούν βασικές λειτουργίες συντήρησης και ελέγχου του συστήματος καθώς και η διευκόλυνση του εκάστοτε χειριστή-υπεύθυνου να το συντηρεί. Η αυτοματοποίηση που επιτεύχθηκε αφορά τρεις διαδικασίες. Η πρώτη και βασικότερη είναι η εύκολη αναγέννηση της βιβλιοθήκης των αρχείων προγραμματισμού του υλικού ειδικού σκοπού του συστήματος (Systems on Chip) που υλοποιείται με κάρτα FPGA. Οι άλλες δύο είναι η διαδικασία εύκολου εντοπισμού κατάλληλων βιολογικών μοντέλων σε βάσεις δεδομένων, και η πιστοποίηση των αποτελεσμάτων που αυτός επιστρέφει με στατιστικά ορθό τρόπο. Η αυτοματοποίηση επιτεύχθηκε με τη δημιουργία κώδικα script σε γλώσσα Python. Πέραν της αυτοματοποίησης, δόθηκε ιδιαίτερη έμφαση και στην υψηλή απόδοση η οποία επιτεύχθηκε με τη χρήση νημάτων που επισπεύδουν την ολοκλήρωση των διαδικασιών. Τα αποτελέσματα της εργασίας είναι ιδιαίτερα ενθαρρυντικά αφού το μόνο πλέον εμπόδιο για την περεταίρω επιτάχυνση των διαδικασιών που αυτοματοποιήθηκαν είναι οι επιδόσεις του υπολογιστή που καλείται να τις εκτελέσει.The goal of this thesis was to support the maintenance of StochSoCs, a pilot computer platform developed at the University of Athens, which combines software and special purpose hardware (FPGA Systems on Chip) for the efficient and parallel stochastic simulation of large-size biological networks, having thousands of interactions between the involved biomolecules. The main objective of this work was to automate three time consuming and error prone maintenance procedures. These are specifically: (a) the regeneration of the hardware simulator's programming files (FPGA bitstreams) every time a modification is made, (b) the search for suitable SBML bio-models in biomodel databases to test the system, (c) the validation of the simulation results in a statistically sound way. The automation of the above procedures has been achieved by developing scripts written in Python. Significant effort was made to improve the efficiency of the scripts using parallelization whenever possible. Apart from the time saved, the possibility of human mistakes, which can be significant in complex multi-step procedures, is totally eliminated. The results obtained are encouraging, since now the only limiting factor in further accelerating these time consuming procedures is the computational power of the computer being used to implement them

H₂S removal by copper enriched porous carbon cuboids

Hydrogen sulfide (H2S) removal by adsorption from gas streams is crucial to prevent the environmental and industrial damage it causes. Amongst the nanostructures considered excellent candidates as sorbents, porous carbon has been studied extensively over the last years. In the present work we present a synthetic procedure for three high potential sorbents based on carbon cuboids, namely a low-surface-area copper-rich structure, a highly porous aggregate without metal addition, and lastly the same porous carbon decorated with copper. The properties and performance as catalysts of these three sorbents were evaluated by powder X-ray diffraction, X-ray photoelectron spectroscopy, thermal analysis, scanning electron microscopy with energy dispersive X-ray analysis, surface area determination through N2 adsorption and desorption, as well as by H2S adsorption measurements

Characterization of Wind-Sea- and Swell-Induced Wave Energy along the Norwegian Coast

The necessity to reduce CO2 emissions in combination with the rising energy demand worldwide makes the extensive use of renewable energy sources increasingly important. To that end, countries with long coastlines, such as Norway, can exploit ocean wave energy to produce large amounts of power. In order to facilitate these efforts as well as to provide quantitative data on the wave energy potential of a specific area, it is essential to analyze the weather and climatic conditions detecting any variabilities. The complex physical processes and the atmosphere-wave synergetic effects make the investigation of temporal variability of wave energy a challenging issue. This work aims to shed new light on potential wave energy mapping, presenting a spatio-temporal assessment of swell- and wind-sea-induced energy flux in the Nordic Seas with a focus on the Norwegian coastline using the NORA10 hindcast for the period 1958–2017 (59 years). The results indicate high spatial and seasonal variability of the wave energy flux along the coast. The maximum wave energy flux is observed during winter, while the minimum is observed during summer. The highest coastal wave energy flux is observed in the Norwegian Sea. The majority of areas with dominant swell conditions (i.e., in the Norwegian Sea) are characterized by the highest coastal wave energy flux. The maximum values of wave energy flux in the North Sea are denoted in its northern parts in the intersection with the Norwegian Sea. In contrast to the Norwegian Sea, areas located in the North Sea and the Barents Sea show that wind sea is contributing more than swell to the total wave energy flux.publishedVersio

The effect of menthol rinsing before intermittent exercise on physiological, physical, and thermo-behavioral responses of male football referees in hot and humid environment

IntroductionIn the current experiment, we aimed to evaluate whether eliciting pre-exercise non-thermal cooling sensations would alter perceptual measures, and physical and physiological responses in football referees.MethodsNine highly trained male football referees undertook two 45-minute intermittent exercise protocols in hot and humid conditions (34.2 ± 0.6°C, 62.5 ± 1.0% relative humidity). In a randomized counterbalanced crossover design, 1 of 2 beverages were given before the warm-up: a 0.01% menthol solution or a placebo noncaloric solution. Physical performance was quantified as total distance covered in each of the three 15-minute exercise blocks. Core temperature, heart rate, thermal sensation and thermal comfort were measured at rest and after each exercise block.ResultsNo changes were observed between trials and over time for distance covered. No main effect of mouth rinse was observed for core temperature and heart rate, but both increased over time in all conditions (P < 0.001). Thermal sensation and thermal comfort were significantly improved with menthol after mouth-rinsing (P < 0.05), but with no differences at any other time-point.DiscussionThese results indicate that non-thermal cooling oral stimuli provide immediate behavioral changes but may not influence physiological or physical responses in football referees, during intermittent exercise in hot and humid environments. Clinical Trial Registrationwww.clinicaltrials.gov, identifier NCT05632692

Interpreting match performance in elite futsal: considerations for normalizing variables using effective time

IntroductionThis study aimed to investigate the physical and individual technical-tactical performance of elite futsal players.MethodsThirteen National Team futsal players (27.4 ± 4.7 years, 70.3 ± 7.6 kg, 176.3 ± 5.5 cm) competed in 15 official matches in three distinct competitions. Session rate of perceived exertion (sRPE) and player load (PL) were measured for assessing physical internal and external load, respectively. Individual tactical actions were analyzed using Instat Scout®, considering variables such as fouls, shots, shots on target, goals, successful dribbles, passes, successful passes, ball losses, ball recoveries, and challenges won.ResultsThe cluster analysis classified the players into two groups: “high-involvement” (HIGH) and “low-involvement” (LOW), based on their average effective playing time, sRPE, and PL. A linear mixed model was used to examine the differences in external and internal load and technical-tactical variables between the two groups, accounting for individual repeated measures. Considering absolute values, HIGH players presented higher sRPE, RPE, total PL, shots, goals, passes, successful passes, ball losses and recoveries, and challenges won (p = 0.001–0.039; ES = 0.43–2.48), when compared to their LOW counterparts. However, when analyzed relative to effective time, LOW players reached higher total PL and shots per minute (p = 0.001–0.012; ES = 0.39–0.93) when compared to HIGH players. Non-significant differences were found for the rest of the variables.DiscussionIn summary, these results emphasize the importance of normalizing internal and external load variables and technical-tactical performance variables per effective playing time in futsal. The current findings indicate that players with lower involvement can present the same or even higher physical and technical-tactical performance compared to teammates with more playing time