132 research outputs found
Lefkias-Georgiadis Anastasios
No full textΑπεικόνιση: ελαιογραφίαΑπεικόνιση αναπαργωγής: κλισέ ελαιογραφία
Sistemi di Depurazione di Acque Reflue Urbane Mediante Infiltrazione Attraverso Colonne di Terreno.
No full textViral vector-mediated RNA interference in the retina
No full textRNA interference (RNAi) is a highly conserved post-transcriptional gene silencing process triggered by double-stranded RNA (dsRNA) in eukaryotic cells. Elucidation of the RNAi regulatory pathway and its components has led to the identification of endogenous dsRNA molecules, termed microRNAs (miRNAs), which are transcribed as a single hairpin molecule prior to their maturation into a cytoplasmic dsRNA. The efficient gene silencing achieved by these short hairpin RNA (shRNA) molecules and the cumulative understanding of the RNAi pathway has prompted the development of hairpin expression vectors capable of mediating stable gene silencing in vitro and in vivo. The aim of this thesis is to evaluate the efficacy of viral vector-mediated RNAi in the retina using recombinant adeno-associated viruses (AAV) and lentiviruses that contain silencing hairpin cassettes to target four genes in murine photoreceptors and the retinal pigment epithelium (RPE).
A detailed assessment of the utility and extend of RNAi in the retina using different viral vectors and hairpin designs is presented in this thesis. Lentiviral and AAV vectors were firstly used to silence GFP in vitro and in vivo as a proof of concept for vector mediated RNAi in the retina. Subsequently, we used lentivirally-mediated RNAi to study disease processes in the retina concentrating on tight junction (TJ) modulators ZO-1 and ZONAB and their role in RPE homeostasis, cell-cycle progression and epithelial-mesenchymal transition (EMT). Here we demonstrated how TJ misregulation can lead to RPE loss, proliferation or dedifferentiation; processes involved in pathological conditions such as atrophic age-related macular degeneration (AMD) and proliferative vitroretinopathy (PVR).
Whilst lentivirally-mediated RNAi was used to elucidate aspects of retinal function and disease, AAV-mediated RNAi was used to probe the therapeutic potential of shRNAs by silencing Peripherin-2 (Prph2), the second most abundant retinal protein, using a miRNA-based hairpin. AAV2/8 particles were used to target endogenous Prph2 and evasion of silencing was demonstrated using an engineered Prph2 cDNA that could be used in a suppression and replacement approach for the treatment of dominant retinal disorders
Synthesis and optimization of NGL separation as a complex energy-integrated distillation sequence
No full textThe synthesis of heat-integrated distillation sequences for energy-efficient separation of zeotropic multicomponent mixtures is complex due to the many interconnected design degrees of freedom. This paper explores the basis on which reliable screening can be carried out. To solve this problem, a screening algorithm has been developed using optimization of a superstructure for the sequence synthesis using shortcut models, in conjunction with a transportation algorithm for the synthesis of the heat integration arrangement. Different approaches for the inclusion of heat integration are explored and compared. Then the best few designs from this screening are evaluated using rigorous simulations. A case study for the separation of NGL is used to compare options. It has been found that separation problems of the type explored can be screened reliably using shortcut distillation models in conjunction with the synthesis of heat exchanger network designs. Unintegrated designs using thermally coupled complex columns show much better performance than the corresponding designs using simple columns. However, once heat integration is included the difference between designs using complex columns and simple columns narrows significantly.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.ChemE/Product and Process Engineerin
Paving the way for the integration of synthesis, assessment, and design tools within an ontological framework
No full textThe constant development of new alternatives to treat waste aids in closing material loops towards the circular economy and improving sustainability through the use of new renewable materials and energy. This fact leads to the increasing need for decision-making tools for process synthesis and assessment, which can be addressed with an integrated framework that employs ontologies for knowledge management and optimization tools to perform a hierarchical assessment of alternatives. The systematization of these procedures raises the need for tools to automate techno-economic and life cycle analyses. In this work, such a challenge is addressed through the additional integration of add-on modules such as the CapEx-Opex estimation tools and surrogate modeling within this framework. A case study on plastic waste is proposed with the inclusion of several pyrolysis and gasification alternatives. Results show pyrolysis, followed by the subsequent purification of its products, as the best alternative and helped identify main drivers for technologies feasibility such as feedstock purity and energy consumption.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.ChemE/Product and Process Engineerin
Enhanced hot-liquid water pretreatment of biomass with recovery and valorization of side products
No full textLignocellulosic biomass potentially represents a great feedstock for biofuel production, but its’ pretreatment needs to be enhanced in order to make biorefineries competitive with fossil fuel based alternatives. One way to make biorefineries more economically viable is to recover and valorize all generated by-products during the biomass pretreatment step. The main goal of this original research is to design an optimal process for recovering valuable by-products after hot-liquid water pretreatment of poplar biomass. Rigorous models for all operations included in the recovery process are developed using Aspen Plus as a CAPE tool. An optimal downstream processing sequence, consisting of multiple distillation steps, is designed to recover several valuable components, such as acetic acid, formic acid, furfural and 5-hydroxymethylfurfural (HMF).Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.BT/Bioprocess EngineeringChemE/Product and Process Engineerin
Ο ρόλος της άσκησης στη διατήρηση της απώλειας σωματικού βάρους σε παχύσαρκα ή υπέρβαρα άτομα
No full textΟ κύριος σκοπός αυτής της μελέτης είναι να αναλύσει τη σχέση μεταξύ της σωματικής δραστηριότητας/άσκησης και της παχυσαρκίας, και να διερευνηθεί εάν η σωματική άσκηση μπορεί να συμβάλλει στη μακροπρόθεσμη διατήρηση της απώλειας του σωματικού βάρους (ΣΒ). Για την εκπόνηση αυτής της βιβλιογραφικής ανασκόπησης, πραγματοποιήθηκε αναζήτηση των σχετικών ερευνών στις ηλεκτρονικές βιβλιογραφικές βάσεις του ΕΚΠΑ, του PubMed, του Google scholar, του NCBI, του Springer, της APA και του Παγκόσμιου Οργανισμού Υγείας. Οι «λέξεις-κλειδιά» που χρησιμοποιήθηκαν ήταν physical activity, exercise, weight loss maintenance, weight regain, aerobic and anaerobic exercise, clinical treatment, diabetes and physical exercise, intensity of exercise, heartrate, perceived effort, Borg scale. Κριτήρια αποκλεισμού μελετών ήταν η δημοσίευσή τους σε γλώσσες εκτός των Ελληνικών και Αγγλικών, μελέτες σε ζώα, έρευνες που περιελάμβαναν άτομα που ελάμβαναν φαρμακευτική αγωγή η οποία θα μπορούσε να επηρεάσει τα αποτελέσματά τους και έρευνες με συμμετέχοντες ηλικίας κάτω των 18 ετών. Κατά την ανασκόπηση της βιβλιογραφίας και βάσει των προαναφερθέντων κριτηρίων βρέθηκαν 9 έρευνες, οι οποίες περιελάμβαναν συμμετέχοντες που είχαν διατηρήσει απώλεια σωματικού βάρους μεγαλύτερη από 10% ή 13.6 κιλά, εκ τον οποίων οι 8 έρευνες έδειξαν ότι η άσκηση/σωματική δραστηριότητα παίζουν σημαντικό ρόλο στην διατήρηση της απώλειας βάρους. Ειδικότερα, η μια από αυτές τις έρευνες έδειξε ότι η διακοπή επίβλεψης των συμμετεχόντων σε πρόγραμμα άσκησης είχε ως συνέπεια τη διακοπή της άσκησης και απώτερη επίπτωση την επανάκτηση του απολεσθέντος βάρους. Η ένταση της άσκησης που εφαρμόστηκε σε 7 από αυτές τις έρευνες ήταν μέτρια έως υψηλή [78±4% της μέγιστης καρδιακής συχνότητας (HRmax) ή ≥ 3 ΜΕΤ (ΜΕΤ:- μεταβολικό ισοδύναμο) και η μορφή της άσκησης ήταν αερόβια, ενώ στις άλλες 2 έρευνες εφαρμόστηκε άσκηση αντιστάσεων με ένταση είτε 20% της 1 μέγιστης επανάληψης (1RM) και 70-80% της μέγιστης καρδιακής συχνότητας, ή 60–80% 1RM και συνολική ενεργειακή δαπάνη 400 θερμίδες ανά συνεδρία. Η διάρκεια της άσκησης που είχε τα καλύτερα αποτελέσματα ήταν ≥ 250 λεπτά εβδομαδιαίως, ενώ ειδικότερα σε μία έρευνα η διάρκεια της άσκησης που οδήγησε σε διατήρηση της απώλειας βάρους 10% ήταν 338 λεπτά εβδομαδιαίως. Ενδεχομένως, η ιδανική εβδομαδιαία διάρκεια άσκησης να ξεπερνάει ακόμα και τα 300 λεπτά/εβδομάδα και για το συγκεκριμένο χαρακτηριστικό της άσκησης (διάρκεια) χρειάζεται να γίνει περεταίρω έρευνα. Σύμφωνα με τα ευρήματα της παρούσας μελέτης, η σωματική άσκηση διαδραματίζει ιδιαίτερα σημαντικό αν όχι απαραίτητο ρόλο στην διατήρηση της αρχικής απώλειας σωματικού βάρους,. Τα βέλτιστα αποτελέσματα παρατηρούνται, όταν η διάρκεια της μέτριας έντασης άσκησης είναι τουλάχιστον 250 λεπτά εβδομαδιαίως. Γενικά, οι σχετικές μελέτες αναδεικνύουν ότι καλύτερα αποτελέσματα παρουσιάζουν τα άτομα που είναι προσηλωμένοι στο πρόγραμμα άσκησής τους, ακολουθούν κατευθυντήριες οδηγίες σε θέματα διατροφής και έχουν σταθερή συμβουλευτική υποστήριξη ως προς τον συγκεκριμένο στόχο. Τέλος, είναι πλέον φανερό ότι τη μακροχρόνια διατήρηση της απώλειας σωματικού βάρους θα επιτύχει το άτομο που θα εντοπίσει ποιο είδος άσκησης απολαμβάνει και μπορεί να το ακολουθήσει για την υπόλοιπη ζωή του. Θα μπορούσε χαρακτηριστικά να διατυπωθεί ότι « Η διαδρομή για την απώλεια βάρους και διατήρησής της είναι μαραθώνιος και όχι σπριντ..! ».The main purpose of this dissertation is to analyze the relationship between physical activity/exercise and obesity, and to investigate whether physical exercise can ultimately contribute to weight loss maintenance. In order to prepare this bibliographic review, a survey was conducted in reputable academic journals, surveys and articles retrieved through the online libraries of EKPA, PubMed, NCBI, Springer, APA and the World Health Organization. The key words used were physical activity, exercise, weight loss maintenance, weight regain, aerobic and anaerobic exercise, clinical treatment, diabetes and physical exercise, intensity of exercise, heart rate, perceived effort, Borg scale. Exclusion criteria were articles published in languages other than Greek and English, animal studies, studies incorporating individuals under medication that could affect the outcomes under investigation and studies that were conducted on individuals less than 18 years of age. Based on the literature review and within the context of the above criteria, 9 original studies were found which had a sample that maintained a weight loss of more than 10% or 13.6 kg. Eight of these studies showed that exercise/physical activity plays an important role in maintaining the weight loss, while one study showed that the cessation of supervision resulted in the cessation of exercise, ultimately leading to regain the weight lost. The exercise intensity used in these studies was moderate to vigorous [78 ± 4% of maximum heart rate (HRmax) or ≥ 3 MET (MET: metabolic equivalent)], the type of exercise was aerobic in 7 of these studies, whereas 2 studies employed either resistance training at an intensity of 20% of 1 maximum repetition (1RM) and 70-80% of maximum heart rate, or 60–80% (1RM) and total calorie expenditure 400 calories per session. The exercise duration producing the best result was ≥ 250 minutes per week, while in one study the duration of exercise that led to the maintenance of 10% of the weight loss was 338 minutes per week, indicating that the ideal exercise duration for weight loss maintenance might be more than 300 min/week. However, more research is needed regarding this issue. According to the findings of the present study, physical exercise plays an important if not a necessary role in maintaining the initial weight loss.. Optimal results are observed when the duration of moderate intensity exercise is at least 250 minutes per week. In general, the relative studies show that people who are focused on their exercise program, follow dietary guidelines and have solid counseling support for this goal demonstrate the best results. Finally, it becomes apparent that long-term maintenance of weight loss is achieved by the person who performs the type of exercise he/she enjoys the most and can follow this for the rest of his/her life. After all, “ the journey of losing weight and maintaining it is a marathon, not a sprint..! ”
Data augmentation for machine learning of chemical process flowsheets
No full textArtificial intelligence has great potential for accelerating the design and engineering of chemical processes. Recently, we have shown that transformer-based language models can learn to auto-complete chemical process flowsheets using the SFILES 2.0 string notation. Also, we showed that language translation models can be used to translate Process Flow Diagrams (PFDs) into Process and Instrumentation Diagrams (P&IDs). However, artificial intelligence methods require big data and flowsheet data is currently limited. To mitigate this challenge of limited data, we propose a new data augmentation methodology for flowsheet data that is represented in the SFILES 2.0 notation. We show that the proposed data augmentation improves the performance of artificial intelligence-based process design models. In our case study flowsheet data augmentation improved the prediction uncertainty of the flowsheet autocompletion model by 14.7%. In the future, our flowsheet data augmentation can be used for other machine learning algorithms on chemical process flowsheets that are based on SFILES notation.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.ChemE/Product and Process Engineerin
Μελέτη λύσεων στο πρόβλημα της κάλυψης φράγματος σε Ασύρματα Δίκτυα Αισθητήρων
No full textΤα Ασύρματα Δίκτυα Αισθητήρων (Wireless Sensor Networks - WSN), έχουν γνωρίσει τεράστια εξέλιξη τα τελευταία δέκα χρόνια και αποτελούν μία περιοχή με μεγάλη ερευνητική δραστηριότητα. Ωστόσο, λόγω κάποιων από τις ιδιαιτερότητές τους, οι κόμβοι ενός ΑΔΑ υπόκεινται σε λειτουργικούς και σχεδιαστικούς περιορισμούς, που δημιουργούν νέες προκλήσεις και αντικείμενα έρευνας με σκοπό τη βελτιστοποίηση της απόδοσης καθώς και της διάρκειας ζωής του δικτύου. Οι ιδιαιτερότητες των δικτύων αυτών δημιουργούν νέα πεδία εφαρμογής, όπως για παράδειγμα ιατρικά, επιστημονικά και επιχειρηματικά πεδία. Αξιοποιούνται, λοιπόν, με επιτυχία σε κάθε είδους εφαρμογές όπως και σε αυτές της ασφάλειας. Η κάλυψη φράγματος αποτελεί ένα από τα πιο κρίσιμα ζητήματα στα ΑΔΑ για τις εφαρμογές ασφάλειας που έχουν ως στόχο τον εντοπισμό των εισβολέων που προσπαθούν να εισέρθουν σε προστατευόμενες περιοχές. Παρ’ όλα αυτά, είναι δύσκολο να επιτευχθεί η επιθυμητή κάλυψη φράγματος μετά από την αρχική τυχαία παράταξη των αισθητήρων επειδή η τοποθεσία τους δεν μπορεί να ελεγχθεί ή να προβλεφθεί. Αντικείμενο της διπλωματικής εργασίας είναι η παρουσίαση αλγορίθμων που βελτιώνουν την ποιότητα της κάλυψης φράγματος τόσο όσον αφορά την καλύτερη κάλυψη μίας περιοχής όσο και την καλύτερη ενεργειακή απόδοση των ίδιων των αισθητήρων. Επιπλέον, οι αλγόριθμοι αυτοί κατατάσσονται με βάση τα πεδία εφαρμογής τους καθώς και με βάση τα μοναδικά τους χαρακτηριστικά. Τέλος, γίνεται αναφορά σε ποια χαρακτηριστικά ενός αλγορίθμου πρέπει να δίνεται προσοχή, τις σχεδιαστικές τους αρχές καθώς και τι επιπλέον θα μπορούσαν οι αλγόριθμοι αυτοί να υποστηρίζουν για το μέλλον.Wireless Sensor Networks (WSN) have seen a tremendous development over the last ten years and they are a region of great research activity. However, because of some of their peculiarities, the nodes of an WSN are subject to functional and design constraints that create new challenges and research objects to optimize performance and network life. The peculiarities of these networks create new fields of application, such as medical, scientific and business fields. They are therefore successfully used in all kinds of security applications. Barrier coverage is one of the most critical issues in security planning applications for detecting invaders attempting to enter protected areas. However, it is difficult to achieve the desired barrier coverage after the initial random alignment of the sensors because their location cannot be controlled or predicted. The aim of the diploma thesis is to present algorithms that improve the quality of barrier coverage both in terms of better area coverage and better energy efficiency of sensors themselves. In addition, these algorithms are ranked according to their application domains and their unique characteristics. Finally, reference is made to which features of an algorithm should be given attention, their design principles as well as what additional these algorithms could support for the future
Transfer learning for process design with reinforcement learning
No full textProcess design is a creative task that is currently performed manually by engineers. Artificial intelligence provides new potential to facilitate process design. Specifically, reinforcement learning (RL) has shown some success in automating process design by integrating data-driven models that learn to build process flowsheets with process simulation in an iterative design process. However, one major challenge in the learning process is that the RL agent demands numerous process simulations in rigorous process simulators, thereby requiring long simulation times and expensive computational power. Therefore, typically short-cut simulation methods are employed to accelerate the learning process. Short-cut methods can, however, lead to inaccurate results. We thus propose to utilize transfer learning for process design with RL in combination with rigorous simulation methods. Transfer learning is an established approach from machine learning that stores knowledge gained while solving one problem and reuses this information on a different target domain. We integrate transfer learning in our RL framework for process design and apply it to an illustrative case study comprising equilibrium reactions, azeotropic separation, and recycles, our method can design economically feasible flowsheets with stable interaction with DWSIM. Our results show that transfer learning enables RL to economically design feasible flowsheets with DWSIM, resulting in a flowsheet with an 8% higher revenue. And the learning time can be reduced by a factor of 2.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.ChemE/Product and Process EngineeringChemE/Delft Ingenious Desig
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