Direct epitaxial growth of polar Hf0.5 Zr0.5 O2 films on corundum

Single-phase epitaxial Hf0.5 Zr0.5 O2 films with non-centrosymmetric orthorhombic structure have been grown directly on electrode-free corundum (a-Al2 O3) substrates by pulsed laser deposition. A combination of high-resolution X-ray diffraction and X-ray absorption spectroscopy confirms the epitaxial growth of high-quality films belonging to the Pca21 space group, with 111] out-of-plane orientation. The surface of a 7-nm-thick sample exhibits an atomic step-terrace structure with a corrugation of the order of one atomic layer, as proved by atomic force microscopy. Scanning transmission electron microscopy reveals that it consists of grains with around 10 nm lateral size. The polar nature of this film has been corroborated by pyroelectric measurements. These results shed light on the mechanisms of the epitaxial stabilization of the ferroelectric phase of hafnia. © 2022 by the authors. Licensee MDPI, Basel, Switzerland

Development of software tool which estimates the carbon footprint and the embodied energy of building constructions, based on the entire life cycle of the building materials.

Η παρούσα διπλωματική εργασία εστιάζει στο αντικείμενο της εκτίμησης του ανθρακικού αποτυπώματος και της συνολικής ενσωματωμένης ενέργειας κτηριακών κατασκευών με βάση ολόκληρο των κύκλο ζωής των δομικών υλικών που χρησιμοποιούνται για την κατασκευή του εκάστοτε κτηρίου. Αυτό επετεύχθη με την ανάπτυξη λογισμικού εργαλείου το οποίο βασίζεται στο περιβάλλον του Microsoft Excel και υπολογίζει το ανθρακικό αποτύπωμα και τη συνολική ενσωματωμένη ενέργεια τόσο ολόκληρου του κτηρίου, όσο και των διαφορετικών δομικών στοιχείων από τα οποία αποτελείται, βοηθώντας, με τον τρόπο αυτό, στην επιλογή του συνδυασμού δομικών υλικών που επιφέρει τις λιγότερες περιβαλλοντικές επιπτώσεις, για νέες κατασκευές, αλλά και στην αξιολόγηση υφιστάμενων. Για την επίτευξη αυτού του σκοπού, χρειάστηκε μία πολύπλευρη προσέγγιση του ζητήματος από διάφορες σκοπιές. Συγκεκριμένα, η εργασία αυτή διαρθρώνεται ως εξής: Καταρχήν, εισάγει τον αναγνώστη στην αναγκαιότητα του περιβαλλοντικού σχεδιασμού των κτηρίων τη σημερινή εποχή, έπειτα, αποτυπώνεται η υφιστάμενη κατάσταση που επικρατεί στον κτηριακό τομέα παγκόσμια. Στην συνέχεια παρουσιάζονται τα δομικά υλικά από τα οποία αποτελείται ένα κτήριο και τα οποία παίζουν μεγάλο ρόλο στις περιβαλλοντικές επιπτώσεις που οφείλονται στην κατασκευή ενός κτηρίου. Ακολουθεί η παρουσίαση, η σύγκριση και η αξιολόγηση των σημαντικότερων εργαλείων περιβαλλοντικής διαχείρισης, ενώ επεξηγείται η μεθοδολογία που χρησιμοποιούν τα διάφορα εργαλεία και πιο αναλυτικά, η Ανάλυση Κύκλου Ζωής (ΑΚΖ), την οποία χρησιμοποιεί και το εργαλείο που αναπτύχθηκε. Έπειτα πραγματοποιείται η ανάπτυξη του λογισμικού εργαλείου, με την ανάλυση των βάσεων δεδομένων που χρησιμοποιήθηκαν, των εκάστοτε παραδοχών, αλλά και του οδηγού χρήσης. Στη μελέτη του αποτυπώματος CO2 συμπεριλαμβάνονται και οι μετακινήσεις των προϊόντων προς τον χώρο του εργοταξίου. Γίνεται εφαρμογή του εργαλείου τόσο για την αξιολόγηση του ανθρακικού αποτυπώματος και της ενσωματωμένης ενέργειας της πρόσφατης ανακαίνισης ξενοδοχειακής μονάδας, όσο και για την κριτική και αξιολόγηση του εργαλείου που αναπτύχθηκε. Τέλος, από τα συμπεράσματα γίνεται σαφής η πολυπλοκότητα του ζητήματος, η αξία της προσπάθειας προσέγγισης του, αλλά και η σημασία της φάσης της κατασκευής του κτηρίου στον κύκλο της ζωής του, η οποία έχει αμεληθεί να ερευνηθεί σε βάθος.This thesis focus on estimating the carbon footprint and the embodied energy of building constructions, based on the entire life cycle of the building materials, used for the construction of each building. This was achieved with the development of a software tool, using Microsoft Excel, which calculates the carbon footprint and the embodied energy of a building as a whole but also for the different components that consist the building. Thus, the tool helps us to choose the most efficient combination of building materials that lead to the least harmful environmental impacts of new buildings, and also to evaluate the environmental hazards of existing buildings. To achieve our goal, it took a multifaceted approach to the issue from different perspectives. Specifically, this thesis is structured as follows: Firstly, it introduces the reader to the necessity of the environmental design of the buildings in our time and then reflects the current situation in the building sector worldwide. After that, there is a presentation of different building materials, which play a large role in the environmental impacts of a building construction. Then, it follows the presentation, the comparison and the evaluation of important environmental management tools and is explained the methodology that such tools use, focusing on the Life Cycle Assessment (LCA), which is also used by the tool developed for this thesis. To continue, there is the development of the software tool, with the analysis of the data bases used, the relevant assumptions which were made and the presentation of the user guide of the tool. The CO2 footprint study, also includes the transport of the products from the place where are produced to the construction site. Then, the tool is applied for a hotel unit, in order to calculate the carbon footprint and the embodied energy of a recent renovation of it, and in addition to criticize and evaluate the tool which was developed. Finally, the conclusions show clearly the complexity and the value of approaching the subject, but also the importance of the construction of the building in its life cycle, which has neglected to be investigated in depth.Αναστάσιος Κ. ΚουτσογιάννηςΙωάννης Π. Παπαδόπουλο

A harmonic analysis view on neuroscience imaging

After highlighting some of the current trends in neuroscience imaging, this work studies the approximation errors due to varying directional aliasing, arising when 2D or 3D images are subjected to the action of orthogonal transformations. Such errors are common in 3D images of neurons acquired by confocal microscopes. We also present an algorithm for the construction of synthetic data (computational phantoms) for the validation of algorithms for the morphological reconstruction of neurons. Our approach delivers synthetic data that have a very high degree of fidelity with respect to their ground-truth specifications. © Springer Science+Business Media New York 2013

Risk factors for hospital admission in patients undergoing outpatient anterior cruciate ligament reconstruction: A national database study

© 2020 Professor P K Surendran Memorial Education Foundation Introduction: Anterior Cruciate Ligament Reconstructions (ACLR) are routinely performed in an outpatient setting with low 90-day readmission rates (2.3%); however, admissions rates in the immediate perioperative period have been previously reported as high as 13.1%. Despite the surprisingly high number of patients requiring immediate perioperative admission, there has been a lack of recent literature specifically examining the associated risk factors for admission. Methods: Using the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database, a query for patients who underwent ACLR from 2011 through 2018 was performed using Current Procedural Terminology codes. The following concomitant procedures were included: meniscectomy, meniscal repair, diagnostic arthroscopy, loose body removal, synovectomy, chondroplasty, abrasion chondroplasty, drilling for osteochondritis dissecans. Demographics including age, sex, race, body mass index (BMI) and comorbidities were collected. Perioperative factors collected were anesthesia type and operative times. Patient demographic and perioperative data were compared using Fisher\u27s exact test and Pearson\u27s chi-square test. Multivariate logistic regressions were used to calculate odds ratios (OR) and 95% confidence intervals (CI) of independent risk factors for postoperative admission. Holm-Bonferroni method yielded adjusted p-value thresholds for significance. Results: Of the 20,819 patients undergoing ACLR with and without concomitant procedures, 3.8% of patients were admitted to the hospital in the immediate postoperative period. Following multivariate regression analysis, increased odds of admission were demonstrated with the use of regional anesthesia alone (OR = 2.77, 95%CI: 2.22–3.44; p \u3c 0.001), increasing concurrent procedures (Table 1), and obesity classes II (OR = 1.62, 95%CI: 1.26–2.10; p \u3c 0.001) and III (OR = 1.81, 95%CI: 1.33–2.47; p \u3c 0.001). Subsequent subgroup analysis of the isolated ACLR procedures (N = 9,423) demonstrated a 3.3% postoperative admission rate. Multivariate regressions demonstrated increased odds of admission with regional anesthesia use only (OR = 2.62, 95%CI: 1.90–3.60; p \u3c 0.001), obesity class II (OR = 2.22, 95%CI: 1.51–3.26; p \u3c 0.001), and increasing minutes of operative time (OR = 1.01, 95%CI: 1.01–1.01; p \u3c 0.001). Table 2 demonstrates increasing rates and odds of admission with increasing operative time in hours. Conclusion: Anterior Cruciate Ligament Reconstructions are routinely performed in an outpatient setting; nevertheless, a subset of ACLR patients is admitted postoperatively. We found an increased risk of admission with the use of regional anesthesia alone, increasing concurrent procedures and obesity classes II and III. A further understanding of patient risk factors for those undergoing ACLR allows orthopedic surgeons to better develop a preoperative plan and discuss patient expectations, which will lead to more efficient resource allocation and improved patient satisfaction