116 research outputs found
Controlled Functionalization of Graphene Layers
No full textControlled functionalization of graphene layers is one of the most important research objectives in the material chemistry. A well established procedure is the oxidation with strong acids and oxidizing agents often in harsh and dangerous reaction conditions giving products of unknown precise structure. In this chapter, the controlled functionalization of graphene layers with a derivative of serinol is presented, avoiding toxic reagents and dangerous reaction conditions. The derivative is the bio‐based serinol pyrrole, obtained through the neat reaction of serinol with 2,5‐hexanedione; the graphitic substrate was high surface area graphite (HSAG) with high‐shape anisotropy. The functionalization reaction, characterized by a 85% atomic efficiency (water is the only by‐product), evolved with high yields leading to functionalized graphene layers through the controlled introduction of oxygen and nitrogen‐containing functional groups. Sustainable processes were adopted, such as ball milling and heating. The mechanism pathway, the characterization of HSAG and reaction products through a wide range of analytical methods, some successful applications of the adducts are discussed in this chapter. The functionalization left the bulk crystalline structure of the layers substantially unaltered. Stable dispersions in water and eco‐friendly solvents were prepared
Nanobubbles in Ultrapure Water Can Self‐Propel
No full textNanobubbles are sub- micron-sized gas entities that find applications in a wide range of scientific fields. Typically, they are thought to diffuse according to Brownian motion. We report the existence of self-propelled motion of oxygen bulk nanobubbles in ultrapure water at body temperature. Their motion, to a large extent, is self-affine; there are different scaling exponents along the x- and y-axes as well as for the lateral displacement. We use fractal analysis, and we calculate the structure function, the normalised velocity autocorrelation function, the skewness, and the kurtosis. All descriptors attest the existence of a quasi-Gaussian stochastic process, which is classified as fractional Brownian motion. More than 50 % of the trajectories along the x-axis follow superdiffusion, while this amount drops to 30 % for motion along the y-axis as a result of the asymmetry of the field of view
Plasma kinetic theory
No full textThe description of plasma using fluid model is mostly insufficient and requires the consideration of velocity distribution which leads to kinetic theory. Kinetic theory of plasma describes and predicts the condition of plasma from microscopic interactions and motions of its constituents. It provides an essential basis for an introductory course on plasma physics as well as for advanced kinetic theory. Plasma kinetics deals with the relationship between velocity and forces and the study of continua in velocity space. Plasma kinetics mathematical equations provide aid to the readers in understanding simple tools to determine the plasma dynamics and kinetics as described in this chapter. Kinetic theory provides the basics and essential introduction to plasma physics and subsequently advanced kinetic theory. Plasma waves, oscillations, frequencies, and applications are the subjects of kinetic theory. In this chapter, mathematical formulations
essential for exploring plasma kinetics are compiled and described simplistically along with a precise discussion on basic plasma parameters in simple language with illustrations in some cases
Kinetic Theory
No full textThe world is governed by motions. The term kinetics partially originated from the Greek word "kinisis," which means motion. How important is motion in our life is easily understood. But, how the kinetic theories have been developed during years? Which are the new kinetic theories and updates in recent years? This question and many others can be answered with this book. Some important areas discussed in this book are the kinetic theory of gases, kinetic theory of liquids and vapors, thermodynamic aspects, transportation phenomena, adsorption-kinetic theories, linear and nonlinear kinetic equations, quantum kinetic theory, kinetic theory of nucleation, plasma kinetic theory, and relativistic kinetic theory
Graphene Materials
No full textGraphene is, basically, a single atomic layer of graphite, an abundant mineral that is an allotrope of carbon that is made up of very tightly bonded carbon atoms organized into a hexagonal lattice. What makes graphene so special is its sp2 hybridization and very thin atomic thickness (of 0.345 Nm). These properties are what enable graphene to break so many records in terms of strength, electricity, and heat conduction (as well as many others). This book gathers valuable information about the surface chemistry of graphene, some of its properties (electrical, mechanical, etc.), and many of its modifications that can be taken into account
From Bubbles to Nanobubbles
No full textNanobubbles are classified into surface and bulk. The main difference between them is that the former is immobile, whereas the latter is mobile. The existence of sNBs has already been proven by atomic force microscopy, but the existence of bNBs is still open to discussion; there are strong indications, however, of its existence. The longevity of NBs is a long-standing problem. Theories as to the stability of sNBs reside on their immobile nature, whereas for bNBs, the landscape is not clear at the moment. In this preliminary communication, we explore the possibility of stabilizing a bNB by Brownian motion. It is shown that a fractal walk under specific conditions may leave the size of the bubble invariant
Διερεύνηση των εμπειριών ασθενών με αγγειακό εγκεφαλικό επεισόδιο από την ενδονοσοκομειακή φροντίδα
No full textΠΕΡΙΛΗΨΗ Αντικείμενο : Το αγγειακό εγκεφαλικό επεισόδιο είναι μία από τις σοβαρότερες παθήσεις του σύγχρονου κόσμου, αποτελώντας τη δεύτερη αιτία θανάτου παγκοσμίως και την τρίτη στην Ελλάδα. Το αντικείμενο της παρούσας εργασίας είναι η διερεύνηση των εμπειριών ασθενών με αγγειακό εγκεφαλικό επεισόδιο από την ενδονοσοκομειακή τους νοσηλεία σε οκτώ δημόσια νοσοκομεία. Υλικό – Μέθοδος : Τριακόσιοι ασθενείς με αγγειακό εγκεφαλικό επεσόδιο παρακολουθήθηκαν για ένα έτος μετά την έξοδό τους από το νοσοκομείο. Έγινε χρήση του εργαλείου NHS Stroke Questionnaire, για το οποίο είχε προηγουμένως εξασφαλιστεί άδεια χρήσης από τον οργανισμό Picker Institute Europe και πραγματοποιηθεί η διαδικασία της αντίστροφης μετάφρασης και της πολιτισμικής προσαρμογής. Για την ασφαλή και ανώνυμη καταγραφή των δεδομένων των συμμετεχόντων, χρησιμοποιήθηκε πολυκαναλική διαδικτυακή πλατφόρμα και πραγματοποιήθηκαν τηλεφωνικές συνεντεύξεις μέσω ερωτηματολογίου εμπειριών, για το χρονικό διάστημα από τον Σεπτέμβριο 2019 έως τον Οκτώβριο 2020. Για τη διερεύνηση σχέσεων των μεταβλητών κατά την πραγματοποίηση των στατιστικών αναλύσεων, εφαρμόστηκε πολλαπλή γραμμική παλινδρόμηση ενώ η ανάλυση των δεδομένων πραγματοποιήθηκε με το πρόγραμμα IBM SPSS 20.0. Αποτελέσματα : Ο πληθυσμός των ασθενών που ανταποκρίθηκαν αφορά 245 συμμετέχοντες με μέσο όρο ηλικίας 72,9 έτη, αποτελούμενος από 124 άνδρες (50,6%) και 121 γυναίκες (49,4%). Η φροντίδα κατά την ενδονοσοκομειακή νοσηλεία αξιολογήθηκε με βάση τις εμπειρίες ως πολύ καλή για το 41,2% και ως εξαιρετική για το 23,7%. Το 91% των συμμετεχόντων απάντησε πως αντιμετωπίστηκε με σεβασμό και αξιοπρέπεια, παρότι το 48,6% δεν ενημερώθηκε για τις παρενέργειες των φαρμάκων. Ακόμα, παρατηρήθηκε έλλειμμα αναφορικά με την παροχή κοινωνικών υπηρεσιών, αν και η πλειονότητα των συμμετασχόντων έκρινε θετικά το έργο των επαγγελματιών υγείας. Συμπεράσματα : Οι εμπειρίες των ασθενών με εγκεφαλικό κρίνονται στην πλειονότητά τους θετικές, αν και προκύπτουν ορισμένες αστοχίες στη φροντίδα που θα πρέπει να αντιμετωπιστούν. Οι εμπειρίες ως εργαλείο αξιολόγησης της φροντίδας εν γένει σε συνδυασμό με μελλοντικές μελέτες σχετικές με το εγκεφαλικό εκτιμάται ότι θα εμπλουτίσουν την έρευνα με περισσότερα δεδομένα.SUMMARY Objective: Cerebrovascular accident is one of the most serious diseases affecting the modern world, being the second leading cause of death worldwide and the third leading cause of death in Greece. The objective of the present study is to investigate the experiences of patients with stroke from their inpatient care in eight public hospitals. Methods: Three hundred patients with cerebrovascular stroke were monitored for one year after discharge from the hospital. NHS Stroke Questionnaire was used, after the permission of Picker Institute Europe. Afterwards, reverse translation and cultural adaptation were performed. A multichannel online platform was utilized for the secure and anonymous registration of the participants’ data and interviews by telephone were carried out. A specific questionnaire of experiences was used for the interviews, which took place from September 2019 until October 2020. Multivariate linear regression was applied for investigating relations between variables throughout statistical analysis. Data analysis was conducted with IBM SPSS 20.0 program. Results: The population of patients who responded consists of 245 participants, with median age of 72,9 years old. The population consisted of 124 men (50,6%) and 121 women (49,4%). Care during inpatient hospitalization was evaluated as very good for 41,2% and as excellent for 23,7% of total participants, based on their experiences. 91 % of them answered that they were treated with respect and dignity, whereas 48,6% was not informed about medical side effects. Moreover, a deficit in the provision of social services was observed, although the majority of the participants welcomed the work of health professionals. Conclusions: Experiences of patients with stroke are evaluated generally as positive, although some mistakes occur in care, which must be confronted. Experiences, as a tool of reforming care combined with future relevant studies, are estimated to enrich research with more data
Διερεύνηση Επιμορφωτικών Αναγκών των καθηγητών Φυσικής Αγωγής του Οργανισμού Πολιτισμού Αθλητισμού Νεολαίας Δήμου Αθηναίων στο πεδίο Εκπαίδευσης Ενηλίκων
No full textΟι καθηγητές Φυσικής Αγωγής, οι οποίοι εντάσσονται στο ανθρώπινο δυναμικό του Οργανισμού Πολιτισμού Αθλητισμού και Νεολαίας του Δήμου Αθηναίων, απασχολούνται άμεσα στο πεδίο της Εκπαίδευσης Ενηλίκων, λειτουργώντας ως εκπαιδευτές ενηλίκων, παρά το γεγονός ότι δεν έχει γίνει συστηματική προσπάθεια, από την πλευρά του Δήμου, για την επιμόρφωσή τους στο συγκεκριμένο επιστημονικό πεδίο. Οι συμμετέχοντες εκπαιδευόμενοι, όμως, στα αθλητικά προγράμματα, τα οποία σχεδιάζουν και υλοποιούν οι καθηγητές Φυσικής Αγωγής, είναι ενήλικοι με διαφορετικές ανάγκες, εμπειρίες και θεωρητικούς προβληματισμούς. Στο πλαίσιο αυτό, είναι απαραίτητο οι καθηγητές Φ.Α. να γνωρίζουν τις βασικές αρχές και τη μεθοδολογία της Εκπαίδευσης Ενηλίκων αφού απευθύνονται σε ενήλικους εκπαιδευόμενους. Ως συνέπεια των παραπάνω, σκοπός της παρούσας έρευνας ήταν η διερεύνηση των επιμορφωτικών αναγκών των καθηγητών Φυσικής Αγωγής στο πεδίο της Εκπαίδευσης Ενηλίκων, ως βασικής παραμέτρου, προκειμένου να διαμορφωθεί ένα Πρόγραμμα Επιμόρφωσής τους στις βασικές αρχές και τη μεθοδολογία της Εκπαίδευσης Ενηλίκων. Δείγμα της συγκεκριμένης έρευνας αποτέλεσαν 90 καθηγητές Φυσικής Αγωγής του εν λόγω οργανισμού, από τους οποίους ζητήθηκε να συμπληρώσουν ένα Ερωτηματολόγιο το οποίο και αποτέλεσε το βασικό ερευνητικό εργαλείο, σε ευθεία αντιστοίχιση, στα πλαίσια της τριγωνοποίησης, με ατομικές συνεντεύξεις από τρεις (3) καθηγητές, προκειμένου να καταστεί εφικτή η επιπλέον διερεύνηση της εγκυρότητας των αποτελεσμάτων από το Ερωτηματολόγιο. Βάσει των αποτελεσμάτων της έρευνας, οι καθηγητές γνωρίζουν, υιοθετούν και αποδέχονται τις αρχές μάθησης ενηλίκων, οι οποίες αναφέρονται στις προϋποθέσεις αποτελεσματικής μάθησης και στα βασικά χαρακτηριστικά των ενηλίκων εκπαιδευομένων ως προς τον τρόπο που μαθαίνουν, συναντούν δυσκολίες στη μεθοδολογία Εκπαίδευσης Ενηλίκων, ως προς τον σχεδιασμό διδακτικών ενοτήτων, στην εναρκτήρια συνάντηση καθώς και στον ρόλο του εκπαιδευτή ενώ στην συντριπτική πλειονότητά τους επιθυμούν επιμόρφωση στην Εκπαίδευση Ενηλίκων με ιεράρχηση των θεματικών περιοχών ως εξής: « Διδακτική Ενηλίκων», «Συμμετοχικές Εκπαιδευτικές Τεχνικές» και «Σχεδιασμός Προγραμμάτων Εκπαίδευσης Ενηλίκων». Ως προς τη μορφή επιμόρφωσης την οποία θα επέλεγαν, προτιμούν τις ημερίδες επιμόρφωσης καθώς και τα ταχύρρυθμα σεμινάρια με επιμορφωτές, όμως, μέλη ΔΕΠ Πανεπιστημιακών Ιδρυμάτων και καθηγητές συμβούλους στο Ε.Α.Π.ABSTRACT Physical Education Instructors, who are integrated in the workforce of the Ο.C.S.Y of the municipality of Athens, are directly involved in the adult Education field, as they are employed to train adults, despite the fact that no systematic effort has been made on behalf of the municipality to educate them on the this specific scientific field. The trainees that participate in the athletic programs, which are designed and actualized by P.E. Instructors, are adults with different needs, experiences and theoretic concerns. Therefore, it is of great importance that P.E. Instructors are familiar with the basic principles and the methodology of Adult Education, since they are orientated towards adults. Aim of this research is to canvass the educational needs of P.E. Instructors on the field of Adult Education so as to develop an Educational Program that corresponds to the basic principles and the methodology of Adult Education. The participants in this research are 100 P.E. Instructors of the Ο.C.S.Y of the municipality of Athens, who were asked to fill in a questionnaire, which was the basic research tool. Additionally three personal interviews with professors were conducted so as to confirm the validity of the questionnaire. Based on the results of the research, the instructors are aware of the learning principles of adult students, they adopt them and accept them since these principles are related to the requirements of effective learning and the basic characteristics of adult learners. The Instructors take into account the way adults learn, they face difficulties as far as the methodology of Adult Education, the development of modules, the first session, and the role of the trainer are concerned. The vast majority of the Instructors/ Trainers seek to Adult Education on themes such as ‘Adult Education Methodology’, ‘Participatory Educational Techniques’ and ‘Adult Education Course Development’. They prefer short term and intensive seminars held by members of Universities and members of H.O.U
A Data-Driven Framework for Probabilistic Estimates in Oil and Gas Project Cost Management: A Benchmark Experiment on Natural Gas Pipeline Projects
No full textNowadays, the Oil and Gas (O&G) industry faces significant challenges due to the relentless pressure for rationalization of project expenditure and cost reduction, the demand for greener and renewable energy solutions and the recent outbreak of the pandemic and geopolitical crises. Despite these barriers, the O&G industry still remains a key sector in the growth of world economy, requiring huge capital investments on critical megaprojects. On the other hand, the O&G projects, traditionally, experience cost overruns and delays with damaging consequences to both industry stakeholders and policy-makers. Regarding this, there is an urgent necessity for the adoption of innovative project management methods and tools facilitating the timely delivery of projects with high quality standards complying with budgetary restrictions. Certainly, the success of a project is intrinsically associated with the ability of the decision-makers to estimate, in a compelling way, the monetary resources required throughout the project’s life cycle, an activity that involves various sources of uncertainty. In this study, we focus on the critical management task of evaluating project cost performance through the development of a framework aiming at handling the inherent uncertainty of the estimation process based on well-established data-driven concepts, tools and performance metrics. The proposed framework is demonstrated through a benchmark experiment on a publicly available dataset containing information related to the construction cost of natural gas pipeline projects. The findings derived from the benchmark study showed that the applied algorithm and the adoption of a different feature scaling mechanism presented an interaction effect on the distribution of loss functions, when used as point and interval estimators of the actual cost. Regarding the evaluation of point estimators, Support Vector Regression with different feature scaling mechanisms achieved superior performances in terms of both accuracy and bias, whereas both K-Nearest Neighbors and Classification and Regression Trees variants indicated noteworthy prediction capabilities for producing narrow interval estimates that contain the actual cost value. Finally, the evaluation of the agreement between the performance rankings for the set of candidate models, when used as point and interval estimators revealed a moderate agreement (a=0.425)
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