Minimally Invasive “IPG-Det Technique” with Autologous CGF and Human Umbilical Cord Blood Derived Mesenchymal Stem Cells towards Posterior Atrophic Maxilla Reconstruction - Case Report

Rehabilitation of maxilla in Implant Dentistry, especially in posterior edentulism is primarily treated with large and painful surgical approaches due to residual ridge atrophy and maxillary sinus pneumatization. Sinus Floor Elevation (SFE), especially in its “lateral version” is considered as the “gold-standard” for over four decades, despite the well documented post-operative morbidity and complications. As an alternative, the novel protocol named “IPG-DET Technique” minimally invasive and equally safe-efficient, promotes sinus membrane intentional perforation secured by healing and augmentative potential of autologous concentrated growth factors and CD34-Stem Cells Matrix. This study further investigates the efficiency and healing process of “IPG-DET Technique” amplified by Mesenchymal Stem Cells clinical use, derived from human Umbilical Cord Blood for posterior atrophic maxilla reconstruction. Preliminary results have shown safe and inductive bone regeneration within sinus cavity. All implants loaded, 4 months after implant placement, showed high primary stability until final fixed prosthetic rehabilitation

Automatic segmentation of closed-contour features in ophthalmic images using graph theory and dynamic programming

This paper presents a generalized framework for segmenting closed-contour anatomical and pathological features using graph theory and dynamic programming (GTDP). More specifically, the GTDP method previously developed for quantifying retinal and corneal layer thicknesses is extended to segment objects such as cells and cysts. The presented technique relies on a transform that maps closed-contour features in the Cartesian domain into lines in the quasi-polar domain. The features of interest are then segmented as layers via GTDP. Application of this method to segment closed-contour features in several ophthalmic image types is shown. Quantitative validation experiments for retinal pigmented epithelium cell segmentation in confocal fluorescence microscopy images attests to the accuracy of the presented technique

Automatic Detection and Classification of Breast Tumors in Ultrasonic Images Using Texture and Morphological Features

Due to severe presence of speckle noise, poor image contrast and irregular lesion shape, it is challenging to build a fully automatic detection and classification system for breast ultrasonic images. In this paper, a novel and effective computer-aided method including generation of a region of interest (ROI), segmentation and classification of breast tumor is proposed without any manual intervention. By incorporating local features of texture and position, a ROI is firstly detected using a self-organizing map neural network. Then a modified Normalized Cut approach considering the weighted neighborhood gray values is proposed to partition the ROI into clusters and get the initial boundary. In addition, a regional-fitting active contour model is used to adjust the few inaccurate initial boundaries for the final segmentation. Finally, three textures and five morphologic features are extracted from each breast tumor; whereby a highly efficient Affinity Propagation clustering is used to fulfill the malignancy and benign classification for an existing database without any training process. The proposed system is validated by 132 cases (67 benignancies and 65 malignancies) with its performance compared to traditional methods such as level set segmentation, artificial neural network classifiers, and so forth. Experiment results show that the proposed system, which needs no training procedure or manual interference, performs best in detection and classification of ultrasonic breast tumors, while having the lowest computation complexity

Μέθοδοι επεξεργασίας και ανάλυσης υπερηχογραφικής εικόνας του θυρεοειδούς αδένα

The aim of the present thesis was the design and implementation of new image processing and analysis methods m ultrasound thyroid images. The research procedure composed two main concepts towards optimization of thyroid ultrasonography. The design and implementation of: 1. Wavelet based image processing methods towards speckle suppression and thyroid nodule segmentation. 2. Image analysis methods in order to evaluate the thyroid nodules malignancy risk factor. 1. Wavelet-Based Image Processing. A remarkable property of the wavelet transform is its ability to characterize the local regularity of image features such as discontinuities and sharp cusps. In mathematics this local regularity is often measured with Lipschitz exponents. In this thesis an investigation has been made to the local behavior of image singularities in terms of Lipschitz regularity in thyroid ultrasound images. The wavelet transform modulus maxima created by noise singularities have a different behavior than those that are mainly affected by image singularities. As an application an algorithm has been developed that removes speckle noise from ultrasound images by analyzing the evolution of wavelet transform modulus maxima across scales. This inter scale search has been implemented by zooming into edges beginning at low resolution (large scales) and adaptively increasing the resolution (small scales) to acquire the necessary details. The two microlocalization properties of these edges that provide characterization of singularities have also been utilized in the subsequent segmentation algorithm. The proposed model transfers the multiscale local maxima representation into a multiscale object representation. Each object that occupies a physical region has been detected by means of local maxima adjacency in all available scales. The multiscale structure representation associates an anatomical object in the image with a volume in the multi scale edge transform. 2. Image Analysis. Finally an investigation of various pattern recognition methods for automatic thyroid nodule discrimination in terms of high and low risk of malignancy has been made. Various pattern recognition algorithms such as Support Vectors Machines (SVMs), the Probabilistic Neural Network (PNN), the classical quadratic least squares minimum distance (QLSMD), the quadratic Bayesian (QB) and the multilayer perceptron (MLP) classifiers have been implemented throughout this thesis. This research comprised two independent studies that employed initially textural features and subsequently morphological and wavelet based features derived from the segmentation procedure. The texture based classification scheme implemented in this study has managed to quantify several textural parameters visually evaluated by physicians in assessing the thyroid nodule’s risk factor and succeeded high classification rates. An additional study has also been made that aimed at the employment of quantified morphological and wavelet based features in order to evaluate the malignancy risk factor in ultrasound thyroid nodules. In this research a novel approach has been made that utilized the image singularities in order to evaluate the effect of speckle in the classification procedure.Η ψηφιακή απεικόνιση του θυρεοειδούς αδένα τόσο μέσω της κλασσικής δισδιάστατης Β Mode εικόνας όσο και μέσω της έγχρωμης απεικόνισης Doppler καθιστά την υπερηχογραφία ένα αξιόπιστο και εύχρηστο μέσο για την κλινική αξιολόγησή του. Η υψηλή διακριτική ικανότητα των συγχρόνων αυτών συστημάτων παρέχει στον Ιατρό την δυνατότητα να εντοπίσει την ύπαρξη οζών - είτε συμπαγών είτε κολλοειδών - στον θυρεοειδή αδένα ακόμα και με διαστάσεις πολύ μικρές (1mm). Επίσης η υπερηχογραφική εικόνα επιτρέπει την λήψη βιοψίας (Fine Needle Aspiration FNAB) σε πραγματικό χρόνο για την περαιτέρω αξιολόγηση του όζου. Το γεγονός ότι τόσο η ηχογένεια όσο και η ύπαρξη διαφορετικών δομών μέσα στους όζους του θυρεοειδή έχουν αποδειχθεί ως σημαντικές ενδείξεις που οδηγούν στην υποψία καρκίνου. Αυτό το γεγονός καθιστά απαραίτητη την έρευνα για τον σχεδιασμό και υλοποίηση αλγορίθμων επεξεργασίας και αναγνώρισης προτύπων στην υπερηχογραφική εικόνα. Η παρούσα διατριβή πραγματεύεται τον σχεδιασμό την ανάπτυξη και υλοποίηση νέων μεθόδων επεξεργασίας και ανάλυσης εικόνων υπερηχογραφίας του θυρεοειδούς αδένα. Οι αλγόριθμοι, οι οποίοι αναπτύχθηκαν και υλοποιήθηκαν αφορούν: Ι. Την αφαίρεση θορύβου (speckle) από τις υπερηχογραφικές εικόνες. Στην παρούσα μελέτη κατά μήκος του μετασχηματισμού μικροκυματιδίων η πληροφορία η οποία βρίσκεται στις διαφορετικές ζώνες συχνότητας (κλίμακες) αναλύεται ώστε να υπολογιστεί η τοπική κανονικότητα των χαρακτηριστικών της εικόνας. Η διακύμανση του πλάτους των τοπικών μέγιστων κατά μήκος των διάφορων κλιμάκων συσχετίζεται με την τοπική κανονικότητα των αντίστοιχων δομών που αντιπροσωπεύουν τα τοπικά μέγιστα. Η έρευνα κατέληξε στην διαπίστωση ότι η κατανομή του speckle - το μοντέλο θορύβου το οποίο υιοθετήθηκε σε αυτήν την διατριβή θεωρεί το speckle σαν έναν αθροιστικό παράγοντα άμεσα εξαρτώμενο από το αρχικό σήμα - είναι σχεδόν παντού σημειακή (singular) με μη θετικούς έκθετες Lipschitz. Αντιθέτως οι χρήσιμες ιδιομορφίες (singularities) που προέρχονται από την φυσιολογική κατανομή των τόνων του γκρι στην υπερηχογραφική εικόνα αποτελούν έντονες αιχμές με θετικούς έκθετες Lipschitz. II. Την τμηματοποίηση των οζών για την απομόνωση τους από τον περιβάλλοντα ιστό. Σε αυτήν την διατριβή ένα υβριδικό μοντέλο εισάγεται για την αυτόματη τμηματοποίηση των οζών του θυρεοειδούς αδένα σε υπερηχογραφικές εικόνες. Η προτεινομένη μέθοδος προκείμενου να ξεπεραστούν οι περιορισμοί λόγω της πολυπλοκότητας της υπερηχογραφικής εικόνας ενσωματώνει στο μοντέλο αυτό τον μετασχηματισμό μικροκυματιδίων για την ανίχνευση αιχμών κατά μήκος των κλιμάκων του μετασχηματισμού με τελικό σκοπό την ταυτόχρονη στερεοσκοπική ανίχνευση της συγκεκριμένης ανατομικής δομής σε όλες τις κλίμακες. III. Την αυτόματη ταξινόμησή τους σε όζους υψηλού και χαμηλού κίνδυνου. Σε αυτήν μελέτη περιλαμβάνονται ασθενείς με όζους του θυρεοειδούς αδένα που εξετάσθηκαν σε ένα υπερηχογραφικό σύστημα και στη συνέχεια υποβλήθηκαν σε διαγνωστική βιοψία με τη μέθοδο FNA στην ιδιωτική κλινική EUROMEDICA. Διάφορα χαρακτηριστικά υφής υπολογίστηκαν αυτόματα από την περιοχή ενδιαφέροντος κάθε όζου. Τα χαρακτηριστικά αυτά συσχετίζονται με τη δομή των τόνων του γκρι αποτελούν χρήσιμη πληροφορία για την πιθανότητα εμφάνισης κακοήθειας. Τέσσερα χαρακτηριστικά υπολογίστηκαν από το ιστόγραμμα 26 από τη μήτρα co-occurrence και 10 από τη μήτρα run length. Τελικά ένα ικανό σύστημα ταξινόμησης σχεδιάστηκε βασισμένο στον αλγόριθμο SVM για την αξιολόγηση του ποσοστού κίνδυνου κακοήθειας σε όζους του θυρεοειδή αδένα σε εικόνες υπερηχογραφίας

Chemistry of uranyl complexes and its relevance to topical technological aspects

The chemistry of actinoids is currently receiving the intense attention of many inorganic chemistry groups around the world. Important scientific challenges for research are handling and recycling nuclear materials, discovering efficient materials for the recovery of the uranyl(VI) cation, trans-UVIO22+, from seawater, investigating the redox properties of these metals, elucidating and manipulating of actinoid-elements multiple-bond interactions, discovering methods to accomplish multi-electron reactions related to organometallic transformations, and improving the 5f-elements potential in small-molecule activation and catalysis. In the hypothetical question ‘’which is the most controversial element in the Periodic Table?’’, U is the most serious candidate because of the unrest over its use and over the consequences of its use. In some cases, it behaves like transition metals, and in others more like a lanthanoid. In its compounds, oxidation states from II to VI are well characterized. Compounds in the IV and VI oxidation states are the most stable. Hexavalent uranium, as the linear uranyl cation, is central to the chemistry of this element.This Doctoral Thesis describes the chemistry of trans-UO22+ with the ligands shown in Scheme I. The organic ligands belong to four(4) families. The first family consists of benzotriazole (btaH) and some of its derivatives (Mebta, 5MebtaH, diMebtaH). The interest in uranyl-benzotriazole complexes arises from the fact that benzotriazole-modified graphene oxide materials are novel adsorbents for removal of U(VI) from aqueous solutions at the optimum pH of 3.5 and the studies show that the nitrogen atoms exhibit strong coordination affinity toward the uranyl(VI) ion. The second family of ligands is composed of symmetrical or asymmetric, tridentate and polydentate Schiff bases, arising from salicylaldehyde or a related ketone and 2-hydroxy-3-methoxy-carbaldehyde (o-vanillin). The uranyl(VI)-Schiff base chemistry is associated with several aspects of contemporary inorganic synthesis, including the functionalization of trans-UO22+, supramolecular chemistry including the ability of uranyl(VI) complexes to act as anion receptors, homogenous catalysis, theoretical chemistry, and separation technologies related to nuclear fuel processing and nuclear waste management. The third family of ligands contains oximes arising from 2-pyridyl ketones and the aldehyde o-vanillin, while the fourth family involves the amidoxime-containing ligands L5H2, L6H2 and NH2pmaoH. Concerning the latter two families, our long-term goals are to (a) enrich the coordination chemistry of such ligands (already well-studied with 3d- and 4f-metal ions) with actinoids, (b) fully investigate and understand the uranyl(VI)-oxime and uranyl(VI)-amidoxime interactions, (c) model the highly selective removal of trans-UO22+ from seawater with amidoxime-functionalized materials, (d) provide evidence towards how a pair of amidoxime groups within a polymer can coordinate to trans-UO22+, (e) present structural comparisons of UO22+ and VO2+ (the main competitor in the recovery of uranium from the oceans) complexes using amidoxime-based ligands, and (f) propose more efficient oxime- or amidoxime-functionalized, high-surface-area polymeric fiber adsorbents. The results of this Thesis with the ligands of the third and fourth families contribute, as we believe, into the goals (a), (b) and (c). For a general reaction system, we tried to isolate the maximum number of products. The uranyl(VI) complexes have been characterized in the solid state by microanalyses (C, H, N), single-crystal X-ray crystallography, IR and Raman spectroscopic methods. The vibrational spectra were discussed in terms of the determined structures of the complexes and the coordination modes of the ligands involved. 1H NMR spectroscopy was the main technique used for the study of the complexes in solution, while ESI(-) MS spectroscopy was used in one case to probe the negatively charged solution species. For the complexes of a given family of ligands, a brief discussion of the technological relevance of the results was also attempted.The Thesis consists of five(5) sections and two Appendices. Appendix I contains routine spectral and structural materials and lists crystallographic data in brief. Appendix II contains short CVs of this PhD candidate in Greek and English. Every section can be read independently; this means that it has its own references list, and the numbering scheme of chapters, figures and tables starts from the beginning. Section I (Introduction) consists of six chapters and every chapter has been written in the form of a review. Chapter A is an overview of the chemistry of actinoids. Chapters B, C, D and E illustrate the basic features of the coordination chemistry of the general families of ligands whose uranyl(VI) complexes are described here. Thus, Chapter B describes the coordination chemistry of benzotriazole and its derivatives, with emphasis on their use for the synthesis of coordination clusters and polymers, and as co-ligands. Chapter C has its focus on the chemistry and coordination chemistry of Schiff bases derived from salicylaldehyde and its derivatives. Chapter D deals with the chemistry and coordination chemistry of the oxime group, with emphasis on metal-involving synthesis and reactions of oximes and coordination complexes of selected 2-pyridyl oximes. Chapter E describes the coordination chemistry and metal-involving reactions of amidoximes. The final chapter of Section I (Chapter F) reviews the current state of the art about the materials for the recovery of uranium from seawater. Section II provides the reader with the general and more specific goals of the Thesis. Section III is the Experimental Part of our work. Chapter A gives detailed information about most of the reagents used and the instruments employed for the characterization of the compounds, while Chapter B details the synthesis of the known (that are not available in the chemical market) and the new organic ligands; for the new ligands L5H2 and L6H2, characterization data are also given. Chapter C describes the detailed preparation of all the uranyl(VI) complexes, along with their characterization data. It is written in such way that a graduate student can reproduce the results. Section IV (Results and Discussion) deals with the full interpretation and study of the data, briefly presented in Section III. It consists of four(4) chapters (A, B, C. D), each describing the complexes of a given family of ligands (please see above). All these chapters have been organized in a uniform manner, each containing three(3) parts (or subchapters). The first part gives synthetic comments, illustrating our philosophy behind the reactions performed. The second part is devoted to the spectroscopic study of the complexes in the solid state and in solution (DMSO). The third part of each of the four chapters deals with the detailed structural description of the complexes, with emphasis on their similarities and differences, and with reference to what is known in the literature. The final Section V (Conclusions and Perspectives) summarizes the main findings, provides a critical discussion of the results and gives some ideas (some of them are in progress) for the future research on topics related to the present Thesis. Some details of the chemistry described in the Thesis are briefly mentioned below. The first employment of benzotriazoles in U chemistry has led to the uranyl(VI) complexes [UO2(NO3)2(btaH)2] (1), [UO2(NO3)2(6MebtaH)2] (2), [UO¬2¬(NO3)2(diMebtaH)2] (3), [UO2(NO3)2(diMebtaH)2]∙(diMebtaH)∙MeCN (4∙diMebtaH∙MeCN) and [UO2(NO3)2-(Mebta)2] (5) with interesting molecular and supramolecular structures. The reactions of UO2(NO3)2∙6H2O with diMebtaH in MeCN give two products depending on the reactants’ molar ratio used. The ligand 5MebtaH tautomerizes upon reaction with UO2(NO3)2∙6H2O in MeCN, leading to compound 2. The benzotriazole molecules act as monodentate ligands with the N atom of the position 3 of the azole ring being the donor atom. We tentatively propose that in benzotriazole-decorated graphene oxide for efficient U(VI) removal from aqueous solution, the benzotriazole is deprotonated, binding the trans-UO22+ cation in an η2 (1.110) mode. The Schiff bases of Scheme I have provided access to the complexes [(UO2)2-(4Me-saph)2(EtOH)2] (6), [(UO2)2(4Cl-saph)2(EtOH)2] (7), [UO2(L1)2] (8), [UO2(L2)(EtOH)] (9), [UO2(L2)(DMF)] (10) and [UO2(MeCO2H)(L3)] (11). The dianions in 6 and 7 behaves as 2.121 ligands and the two UVI atoms are bridged by two phenoxido O atoms that belong to the methyliminophenlato (6) or chloroiminophenolato (7) parts of the two doubly deprotonated ligands. Upon maximum excitation at 445 nm, a green light emission with a maximum at 563 nm has been recorded for solid 7 at room temperature. The monoanionic ligand (L1)- adopts two different ligation modes, 1.1011 and 1.1010, in complex 8. Despite their different structural formula and nature, the dianionic ligands (L2)2- and (L3)2- in 9-11 both bind with the Ophenolato, Nimine, N΄imine, O΄phenolato mode (1.1111, 1.110011). We had designed the ligand L3H2 with the hope that its dianionic form would act as hexadentate chelating (1.111111) ligand. If that were the case, (L3)2- would have been an ideal agent for the extraction of trans-UO22+ and its separation from trivalent lanthanoids in the nuclear wastes; however, this did not turn out to be the case. Work is in progress in our laboratory to synthesize such ligands with six(6) donor atoms that can occupy six(6) equatorial positions around the uranyl(VI) cation in a hexagonal bipyramidal coordination environment. Detailed synthetic investigations of various UO22+/mpkoH, UO22+/ppkoH and UO22+/L3H2 reaction systems have provided access to the complexes [UO2(mpko)2-(MeOH)2]{[UO2(NO3)(mpko)(MeOH)2]}2 (12), [UO2(mpko)2(MeOH)2] (13), [(UO2)2(O2)-(O2CMe)2(mpkoH)2] (14), [UO2(ppko)2(MeOH)2] (15) και (Et3NH)2[(UO2)4(O)2(L4)2(L4H)2] (16). The peroxido group in 14, which was isolated without the addition of external peroxide sources, probably arises from a bis(aquo)- and/or bis(hydroxido)-bridged diuranyl(VI) precursor in solution followed by photochemical oxidation of the bridging groups. The UVI atom in the [UO2(NO3)(mpko)(MeOH)2] molecules (1A) of 12 is surrounded by one N and seven O atoms in a very distorted hexagonal bipyramidal geometry; two oxygen atoms from the terminal MeOH ligands, two oxygen atoms from the bidentate chelating nitrato group, and the oxygen and nitrogen atoms from the η2 oximate group of the 1.110 mpko- ligand define the equatorial plane. This plane consists of two terminal MeOH ligands and two η2 oximato groups in the [UO2(mpko)2(MeOH)2] molecule (1B) of 12. The structure of the [UO2(mpko)2(MeOH)2] molecule that is present in 13 is very similar to the corresponding molecule in 12. The structure of the dinuclear molecule that is present in 14 consists of two {UO2(O2CMe)(mpkoH)}+ units bridged by an η2:η2:μ2-Ο22- group. The equatorial plane of each uranyl(VI) site is composed of the 2-pyridyl and oxime nitrogen atoms of a 1.011 mpkoH ligand, the oxygen atoms of an almost symmetrically coordinated bidentate chelating MeCO2- group and the two oxygen atoms of the peroxido group. The core molecular structure of 15 is similar to that of 13, the only difference being the presence of 1.110 ppko- ligands in the former, instead of mpko- groups in the latter. The free pyridyl nitrogen atoms of mpko- and ppko ligands of 12, 13 and 15 are acceptors of intramolecular H bonds from the ligated MeOH oxygen atoms. H-bonding and π-π stacking interactions build interesting supramolecular networks in the crystal structures of the four complexes. Complexes 12-15 are the first structurally characterized uranyl(VI) complexes with 2-pyridyl aldoximes or ketoximes as ligands. 1H NMR data in DMSO-d6 suggest that the complexes decompose in solution. The ESI(-) MS spectrum of 15, dissolved in a (NH4)(O2CMe) buffer, is indicative of the presence of [UO2(O2CMe)3]-, [UO2(O2CMe)2(ppko)]-, [UO2(O2CMe)(ppko)2]- and [UO2(ppko)3]- species. A common structural motif of 12, 13 and 15 is that the deprotonated oximate group prefers to bind in the η2 (1.11) fashion, forming a 3-membered chelating ring in spite of the presence of a 2-pyridyl nitrogen atom, whose coordination would be expected to lead to 5- or 6-membered chelating rings. Complex 16 is one of the very few tetranuclear uranyl(VI) clusters reported to date. The core of the tetranuclear anion is {UVI4(μ3-Ο)2(μ2-OR)2} and the four(4) metal centers adopt a ‘’butterfly’’ topology. The (L4H)- and (L4)2- ligands adopt the 2.1201 and 2.0111 coordination modes, respectively. The UVI centers possess a distorted pentagonal bipyramidal coordination geometry. Of particular structural importance is the deviation from strict linearity in two symmetrically-related trans-UO22+ groups (O=UVI=O, 175.1 °) due to the participation of one uranyl(VI) oxido atoms in a relatively strong H bonds. The reaction of uranyl(VI) sources with the amidoxime-containing ligands L5H2, L6H2 and NH2pmaoH gave complexes [(UO2)2(NO3)2(L5H)2] (17), [(UO2)2(O2CMe)2(L5H)2] (18), [(UO2)2(L5)2(DMSO)2] (19), [(UO2)2(O2CMe)2(L6H)2] (20), two different compounds [(UO2)2(L6)2(DMSO)2] (21 and 22) containing different amounts of lattice solvents, two different compounds [(UO¬2)2(L6)2(DMF)2] (23 and 24) containing different amounts of lattice solvents and [UO2(NH2pmao)2(MeOH)2] (25). Since the free ligands L5H2 and L6H2 are new, their full characterization was carried out which also involved the single-crystal X-ray structure of L6H2. In the solid state, the two compounds exist in their keto forms, while in DMSO their enol forms dominate. The two ligands behave similarly towards the uranyl(VI) cation, suggesting that the Me/Ph substitution has no effect on the molecular structures of the products. Two series of dinuclear complexes were synthesized, one containing the singly deprotonated (L5H)- (17, 18) and (L6H)- (20) ligands and the other involving the doubly deprotonated (L5)2- (19) and (L6)2- (21-24) ligands. In complexes 17, 18 and 20, the ligands are in their keto forms and adopt the 2.11100 coordination mode. In complexes 19 and 21-24, the doubly deprotonated ligands are in their enolate forms and adopt the 2.21110 coordination mode. In the complexes with the singly deprotonated ligands, the amidoximato(-1) groups participate in the syn, anti-η1:η1:μ2 (2.110) mode with their oximato moieties providing the bridges between the two uranyl(VI) centers. On the contrary, in the complexes with the doubly deprotonated ligands, the amidoximato(-1) groups adopt the η2 (1.11) mode, resulting in the formation of unusual (but stable) 3-membered chelating rings, with the enolato oxygen atoms providing the monoatomic bridges between the two uranyl(VI) sites. The anionic NH2pmao- ligands in 25 adopt the 1.11000 coordination mode, resulting in the formation of two 3-membered ONU chelating rings per trans-UO22+, with the four(4) nitrogen atoms of the two pyrimidine rings remaining uncoordinated. This complex has a similar molecular structure with that of the 1B molecule in 12, and with the structures of complexes 13 and 15. The amino groups in the amidoximato(-1) moiety is ‘’free’’, i.e. not coordinated, in all complexes 17-25. The η2 (1.11) ligation mode of the oximato group is believed to be a decisive factor for the selective complexation of UO22+ (and its removal from seawater) in amidoxime-containing adsorbents; this ligation mode has been crystallographically confirmed in complexes 19 and 21-24. What is a new discovery in the present work, is that the amidoximato(-1) group does not always adopt the η2 mode towards the uranyl(VI) cation (as it was believed until now), but its behavior (chelating or bridging) depends on the nature and charge of the neighboring potential donor atoms, with which the amidoximato(-1) oximate-type nitrogen atom can participate in stable 5- or 6-membered chelating rings.In summary, we believe that this Thesis is a contribution into the chemistry of trans-UO22+, and into the coordination chemistry of simple benzotriazoles, Schiff bases arising from salicylaldehyde, o-vanillin and its derivatives, oximes (particularly of 2-pyridyl ketoximes) and amidoximes. We shall be happy if the eminent reviewers and the readers of this PhD Thesis share our view.Η χημεία των ακτινοειδών συγκεντρώνει σήμερα το έντονο ενδιαφέρον ερευνητικών ομάδων Ανόργανης Χημείας Παγκοσμίως. Σημαντικές ερευνητικές προκλήσεις είναι ο χειρισμός και η ανακύκλωση των πυρηνικών υλικών, η ανακάλυψη αποτελεσματικών υλικών για την ανάκτηση του κατιόντος του ουρανυλίου(IV), trans-UVIO22+, από το θαλασσινό νερό, η έρευνα για τις οξειδοαναγωγικές ιδιότητες αυτών των μετάλλων, η σύνθεση και η δραστικότητα ενώσεων με πολλαπλούς δεσμούς μεταξύ των ακτινοειδών και άλλων στοιχείων, η ανακάλυψη μεθόδων για την πραγματοποίηση αντιδράσεων πολλών ηλεκτρονίων σε σχέση με οργανομεταλλικούς μετασχηματισμούς και η βελτίωση της δυνατότητας των 5f-στοιχείων για την ενεργοποίηση μικρών μορίων και τη συμμετοχή τους σε καταλυτικές διεργασίες. Στην υποθετική ερώτηση ‘’ποιό είναι το πλέον αμφιλεγόμενο στοιχείο του Περιοδικού Πίνακα;’’, το U θα ήταν ο πρώτος υποψήφιος για την αναστάτωση που προκαλεί η χρησιμοποίησή του αλλά και για τα ερωτήματα που εγείρει αυτή η χρησιμοποίηση. Όσον αφορά στη χημεία του, το ουράνιο συχνά συμπεριφέρεται ως μεταβατικό μέταλλο, ενώ σε άλλες περιπτώσεις παρουσιάζει συμπεριφορά ανάλογη των λανθανοειδών. Στις ενώσεις του είναι καλά χαρακτηρισμένες οι οξειδωτικές καταστάσεις II-VI. Οι ενώσεις με το μέταλλο στις οξειδωτικές βαθμίδες IV και VI είναι οι πλέον σταθερές. Η θερμοδυναμικά σταθερή μορφή του U(VI) είναι το γραμμικό trans κατιόν του ουρανυλίου. Η παρούσα Διδακτορική Διατριβή περιγράφει τη χημεία του trans-UO22+ με τους υποκαταστάτες που εικονογραφούνται στο Σχήμα Ι. Οι οργανικοί αυτοί υποκαταστάτες ανήκουν σε τέσσερις(4) οικογένειες. Η πρώτη οικογένεια αποτελείται από το βενζοτριαζόλιο (btaH) και μερικά παράγωγά του (Mebta, 5MebtaH, diMebtaH). Το ενδιαφέρον στα σύμπλοκα ουρανυλίου(VI)-βενζοτριαζολίων προέρχεται από το γεγονός ότι υλικά που αποτελούνται από οξείδιο του γραφενίου τροποποιημένου με βενζοτριαζόλια είναι εξαιρετικά προσροφητικά μέσα για την απομάκρυνση του U(VI) από υδατικά διαλύματα σε βέλτιστη τιμή pH 3.5, και μελέτες έχουν δείξει ότι τα άτομα αζώτου συμπλοκοποιούνται ισχυρά με το ουρανύλιο. Η δεύτερη οικογένεια υποκαταστατών συνίσταται από συμμετρικές ή ασύμμετρες τριδοντικές και πολυδοντικές βάσεις Schiff που προκύπτουν από τη σαλικυλική αλδεΰδη ή μια κετόνη της και την 2-υδροξυ-3-μεθοξυ-καρβαλδεΰδη (ο-βανιλίνη). Η χημεία του ουρανυλίου(VI) με βάσεις Schiff είναι στενά συνδεδεμένη με διάφορους τομείς της σύγχρονης ανόργανης σύνθεσης, συμπεριλαμβανομένης και της υποκατάστασης/ενεργοποίησης του trans-UO22+, της υπερμοριακής χημείας συμπεριλαμβανομένης της ικανότητας των συμπλόκων του ουρανυλίου(VI) να δρουν ως υποδοχείς ανιόντων, της κατάλυσης, της Θεωρητικής Χημείας και των τεχνολογιών διαχωρισμού που σχετίζονται με την επεξεργασία των πυρηνικών καυσίμων και τη διαχείριση των πυρηνικών αποβλήτων. Η τρίτη οικογένεια των υποκαταστατών περιλαμβάνει οξίμες που προέρχονται από 2-πυρίδυλο κετόνες και την οξίμη της ο-βανιλίνης, ενώ η τέταρτη οικογένεια περιέχει τους υποκαταστάτες L5H2, L6H2 και NH2pmaoH που ενέχουν την αμιδοξιμική ομάδα. Όσον αφορά στις δύο τελευταίες οικογένειες υποκαταστατών, οι μακροπρόθεσμοι στόχοι μας είναι να (α) εμπλουτίσουμε τη χημεία ένταξης αυτών των υποκαταστατών (που μερικοί έχουν χρησιμοποιηθεί με τα 3d- και 4f-μεταλλικά ιόντα) με ακτινοειδή, (β) ερευνήσουμε και να κατανοήσουμε τις αλληλεπιδράσεις ουρανυλίου(VI)-οξιμικής ομάδας και ουρανυλίου(VI)-αμιδοξιμικής ομάδας, (γ) μοντελοποιήσουμε την εκλεκτική απομάκρυνση του trans-UO22+ από το θαλασσινό νερό με υλικά που περιέχουν την αμιδοξιμική λειτουργική ομάδα, (δ) προσεγγίσουμε και μοντελοποιήσουμε τον τρόπο με τον οποίο ένα ζεύγος αμιδοξιμικών ομάδων σε ένα πολυμερές μπορεί να συμπλοκοποιηθεί με το trans-UO22+, (ε) συγκρίνουμε τη δομική χημεία των συμπλόκων των UO22+ και VO2+ (το κύριο ιόν που συναγωνίζεται την ανάκτηση του ουρανυλίου από τους ωκεανούς) με αμιδοξιμικούς υποκαταστάτες, και (στ) προτείνουμε πιο αποτελεσματικά ινώδη πολυμερικά προσροφητικά μέσα που θα έχουν τροποποιηθεί για να περιέχουν οξιμικές ή αμιδοξιμικές ομάδες. Τα αποτελέσματα αυτής της Διατριβής συνεισφέρουν, όπως πιστεύουμε, στην υλοποίηση των στόχων (α), (β) και (γ).Για δεδομένο γενικό σύστημα αντίδρασης, προσπαθήσαμε να απομονώσουμε το μέγιστο αριθμό προϊόντων. Τα σύμπλοκα του ουρανυλίου(VI) χαρακτηρίστηκαν στη στερεά κατάσταση με μικροαναλύσεις (C, H, N), κρυσταλλογραφία ακτίνων Χ σε μονοκρύσταλλο, καθώς και με φασματοσκοπικές μεθόδους IR και Raman. Πραγματοποιήθηκε μελέτη των δονητικών φασμάτων σε σχέση με τις επιλυθείσες δομές των συμπλόκων και τους τρόπους ένταξης των υποκαταστατών που υπεισέρχονται σε αυτά. Η φασματοσκοπία 1H NMR ήταν η κύρια τεχνική που χρησιμοποιήθηκε για τη μελέτη των συμπλόκων σε διάλυμα, ενώ σε μια περίπτωση καταγράφηκαν φάσματα ESI(-)-MS για να εξακριβωθούν τα αρνητικώς φορτισμένα χημικά είδη που υπάρχουν στο διάλυμα. Για τα σύμπλοκα της καθεμιάς οικογένειας υποκαταστατών, επιχειρήθηκε μια πρώτη συσχέτιση των αποτελεσμάτων με τεχνολογικά θέματα σύγχρονου ενδιαφέροντος. Η Διατριβή αποτελείται από πέντε(5) Μέρη και δύο(2) Παραρτήματα. Το Παράρτημα Ι περιέχει πολλά φασματοσκοπικά και δομικά δεδομένα ρουτίνας, καθώς επίσης και πολύ βασικά κρυσταλλογραφικά δεδομένα. Το Παράρτημα ΙΙ περιλαμβάνει σύντομα Βιογραφικά Σημειώματα του υποψηφίου στην Ελληνική και στην Αγγλική. Κάθε Μέρος μπορεί να διαβαστεί ανεξάρτητα. Αυ

Medical Imaging Devices Assessment at Public Health Sector of Greece. Risk-Based Maintenance: A Decision Support Model

Abstract Introduction: Medical imaging equipment such as ultrasound, X-ray, Computed Tomography and Magnetic Resonance Imaging systems are essential in modern hospital operation. They have the capacity to promote public health under the condition that they operate with high reliability and safety requirements. Aim: The aforementioned prerequisites necessitate an efficient maintenance planning that could keep these devices in good condition at the minimum cost. The rare economic resources in Greece due to the recession have made this task rather difficult. Methodology: A risk-based decision support model is introduced in this study towards the debate whether to maintain or not a medical imaging device. Several parameters and metrics have been utilized as input in the decision algorithm in order to produce optimum decision regarding the need to maintain a certain device. These include availability, key performance indicators, risk and economic factors. These metrics are capable of capturing all the information that is significant for each medical imaging device. Results: A case study has been made in this study that utilized an x-ray imaging C-arm towards efficient decision making regarding maintenance that employed all the metrics of the last two years where the C-arm imaging device is without a preventive maintenance contract with the manufacturer. Conclusions: The decision model introduced in this study could be of value for the hospital management and provide important information regarding the condition of each medical imaging device and possible future failures

Synthetic and Structural Chemistry of Uranyl-Amidoxime Complexes: Technological Implications

Resource shortage is a major problem in our world. Nuclear energy is a green energy and because of this and its high energy density, it has been attracting more and more attention during the last few decades. Uranium is a valuable nuclear fuel used in the majority of nuclear power plants. More than one thousand times more uranium exists in the oceans, at very low concentrations, than is present in terrestrial ores. As the demand for nuclear power generation increases year-on-year, access to this reserve is of paramount importance for energy security. Water-insoluble polymeric materials functionalized with the amidoxime group are a technically feasible platform for extracting uranium, in the form of {UO2}2+, from seawater, which also contains various concentrations of other competing metal ions, including vanadium (V). An in-depth understanding of the coordination modes and binding strength of the amidoxime group with uranyl and other competing ions is a key parameter for improving extraction efficiency and selectivity. Very limited information on the complexation of {UO2}2+ with amidoximes was available before 2012. However, significant advances have been made during the last decade. This report reviews the solid-state coordination chemistry of the amidoxime group (alone or within ligands with other potential donor sites) with the uranyl ion, while sporadic attention on solution and theoretical studies is also given. Comparative studies with vanadium complexation are also briefly described. Eight different coordination modes of the neutral and singly deprotonated amidoxime groups have been identified in the structures of the uranyl complexes. Particular emphasis is given to describing the reactivity of the open-chain glutardiamidoxime, closed-ring glutarimidedioxime and closed-ring glutarimidoxioxime moieties, which are present as side chains on the sorbents, towards the uranyl moiety. The technological implications of some of the observed coordination modes are outlined. It is believed that X-ray crystallography of small uranyl-amidoxime molecules may help to build an understanding of the interactions of seawater uranyl with amidoxime-functionalized polymers and improve their recovery capacity and selectivity, leading to more efficient extractants. The challenges for scientists working on the structural elucidation of uranyl coordination complexes are also outlined. The review contains six sections and 95 references