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Pouroutzidou GK, Papadopoulou L, Lazaridou M, Tsachouridis K, Papoulia C, Patsiaoura D, Tsamesidis I, Chrissafis K, Vourlias G, Paraskevopoulos KM, Anastasiou AD, Bikiaris DN, Kontonasaki E. Composite PLGA–Nanobioceramic Coating on Moxifloxacin-Loaded Akermanite 3D Porous Scaffolds for Bone Tissue Regeneration. Pharmaceutics 2023; 15:pharmaceutics15030819. [PMID: 36986685 PMCID: PMC10053907 DOI: 10.3390/pharmaceutics15030819] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 02/18/2023] [Accepted: 02/27/2023] [Indexed: 03/06/2023] Open
Abstract
Silica-based ceramics doped with calcium and magnesium have been proposed as suitable materials for scaffold fabrication. Akermanite (Ca2MgSi2O7) has attracted interest for bone regeneration due to its controllable biodegradation rate, improved mechanical properties, and high apatite-forming ability. Despite the profound advantages, ceramic scaffolds provide weak fracture resistance. The use of synthetic biopolymers such as poly(lactic-co-glycolic acid) (PLGA) as coating materials improves the mechanical performance of ceramic scaffolds and tailors their degradation rate. Moxifloxacin (MOX) is an antibiotic with antimicrobial activity against numerous aerobic and anaerobic bacteria. In this study, silica-based nanoparticles (NPs) enriched with calcium and magnesium, as well as copper and strontium ions that induce angiogenesis and osteogenesis, respectively, were incorporated into the PLGA coating. The aim was to produce composite akermanite/PLGA/NPs/MOX-loaded scaffolds through the foam replica technique combined with the sol–gel method to improve the overall effectiveness towards bone regeneration. The structural and physicochemical characterizations were evaluated. Their mechanical properties, apatite forming ability, degradation, pharmacokinetics, and hemocompatibility were also investigated. The addition of NPs improved the compressive strength, hemocompatibility, and in vitro degradation of the composite scaffolds, resulting in them keeping a 3D porous structure and a more prolonged release profile of MOX that makes them promising for bone regeneration applications.
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Affiliation(s)
- Georgia K. Pouroutzidou
- Advanced Materials and Devices Laboratory, Faculty of Sciences, School of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
- Department of Prosthodontics, Faculty of Health Sciences, School of Dentistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
- Correspondence: (G.K.P.); (E.K.)
| | - Lambrini Papadopoulou
- School of Geology, Faculty of Sciences, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Maria Lazaridou
- Faculty of Sciences, School of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Konstantinos Tsachouridis
- Department of Chemical Engineering and Analytical Science, University of Manchester, Manchester M1 3AL, UK
| | - Chrysanthi Papoulia
- Advanced Materials and Devices Laboratory, Faculty of Sciences, School of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Dimitra Patsiaoura
- Advanced Materials and Devices Laboratory, Faculty of Sciences, School of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Ioannis Tsamesidis
- Department of Prosthodontics, Faculty of Health Sciences, School of Dentistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Konstantinos Chrissafis
- Advanced Materials and Devices Laboratory, Faculty of Sciences, School of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - George Vourlias
- Advanced Materials and Devices Laboratory, Faculty of Sciences, School of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Konstantinos M. Paraskevopoulos
- Advanced Materials and Devices Laboratory, Faculty of Sciences, School of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Antonios D. Anastasiou
- Department of Chemical Engineering and Analytical Science, University of Manchester, Manchester M1 3AL, UK
| | - Dimitrios N. Bikiaris
- Faculty of Sciences, School of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Eleana Kontonasaki
- Department of Prosthodontics, Faculty of Health Sciences, School of Dentistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
- Correspondence: (G.K.P.); (E.K.)
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Malletzidou L, Zorba TT, Kyranoudi M, Mastora P, Karfaridis D, Vourlias G, Pavlidou E, Paraskevopoulos KM. The dome of Rotunda in Thessaloniki: Investigation of a multi-pictorial phase wall painting through analytical methods. Spectrochim Acta A Mol Biomol Spectrosc 2021; 262:120101. [PMID: 34198121 DOI: 10.1016/j.saa.2021.120101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Revised: 06/02/2021] [Accepted: 06/20/2021] [Indexed: 06/13/2023]
Abstract
The present study focuses on the investigation of the successive pictorial phases of the wall painting which survives on the missing eastern part of the magnificent mosaic composition in the interior of Rotunda, Thessaloniki, Greece. Rotunda, a circular domed monumental building, was constructed in the early 4th century AD and it is included in the UNESCO World Heritage List. Characterization analysis was performed by means of microscopic, spectroscopic and crystallographic techniques, in order to identify the technological features of the wall painting and the materials used, to document the initial Byzantine pictorial phase -known from the archaeological research- along with the overpaintings attributed to the 19th and 20th centuries. In this framework, the collected samples were studied with optical microscopy, Fourier transform infrared micro-spectroscopy, scanning electron microscopy, X-ray diffractometry and X-ray photoelectron spectroscopy. Among the detected materials and pigments (including zinc oxide, barium sulfate, red lead, green earth, Prussian blue, emerald green, ultramarine and cuprite), the use of brass powder for false gilding purposes was detected, which is a material rarely used for mural applications.
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Affiliation(s)
- Lamprini Malletzidou
- School of Physics, Faculty of Sciences, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece.
| | - Triantafyllia T Zorba
- School of Physics, Faculty of Sciences, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece
| | - Maria Kyranoudi
- School of Physics, Faculty of Sciences, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece; Ephorate of Antiquities of Thessaloniki City, Eptapyrgio, GR-54003, P.O. Box 18432, Thessaloniki, Greece
| | - Pelli Mastora
- Ephorate of Antiquities of Thessaloniki City, Eptapyrgio, GR-54003, P.O. Box 18432, Thessaloniki, Greece
| | - Dimitrios Karfaridis
- School of Physics, Faculty of Sciences, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece
| | - George Vourlias
- School of Physics, Faculty of Sciences, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece
| | - Eleni Pavlidou
- School of Physics, Faculty of Sciences, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece
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Kelesi M, Kontonasaki E, Kantiranis N, Papadopoulou L, Zorba T, Paraskevopoulos KM, Koidis P. The effect of different aging protocols on the flexural strength and phase transformations of two monolithic zirconia ceramics. J Appl Biomater Funct Mater 2020; 18:2280800020982677. [DOI: 10.1177/2280800020982677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Introduction: The aim of the present study was to investigate how different aging protocols can affect the flexural strength and phase transformations of yttrium-stabilized zirconia ceramics (Y-TZP) for monolithic restorations. Materials and methods: Bar-shaped specimens from two zirconia ceramics bars were divided into three groups: a. no treatment (c), b. aging in an autoclave (a), and c. thermal cycling (t). The flexural strength was determined by the 3-point bending test and statistical analysis was performed to determine significant differences ( p< 0.05). Weibull statistics was used to analyze the dispersion of strength values while surface microstructural analysis was performed through X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Results: Aging did not significantly affect the flexural strength but differences were recorded between the two groups, with group A presenting higher strength values and m-phase percentages. Conclusions: The observed differences between the two ceramics could be attributed to variations in composition and processing.
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Affiliation(s)
- Maria Kelesi
- Laboratory of Prosthodontics, Dentistry Department, Faculty of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Eleana Kontonasaki
- Laboratory of Prosthodontics, Dentistry Department, Faculty of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Nikolaos Kantiranis
- Geology Department, Faculty of Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Lambrini Papadopoulou
- Geology Department, Faculty of Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Triantafyllia Zorba
- Physics Department, Faculty of Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - K M Paraskevopoulos
- Physics Department, Faculty of Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Petros Koidis
- Laboratory of Prosthodontics, Dentistry Department, Faculty of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
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Pouroutzidou GK, Theodorou GS, Kontonasaki E, Tsamesidis I, Pantaleo A, Patsiaoura D, Papadopoulou L, Rhoades J, Likotrafiti E, Lioutas CB, Chrissafis K, Paraskevopoulos KM. Effect of ethanol/TEOS ratios and amount of ammonia on the properties of copper-doped calcium silicate nanoceramics. J Mater Sci Mater Med 2019; 30:98. [PMID: 31440844 DOI: 10.1007/s10856-019-6297-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 07/31/2019] [Indexed: 06/10/2023]
Abstract
Calcium magnesium silicate glasses could be suggested for the synthesis of scaffolds for hard tissue regeneration, as they present a high residual glassy phase, high hardness values and hydroxyapatite-forming ability. The use of trace elements in the human body, such as Cu, could improve the biological performance of such glasses, as Cu is known to play a significant role in angiogenesis. Nano-bioceramics are preferable compared to their micro-scale counterparts, because of their increased surface area, which improves both mechanical properties and apatite-forming ability due to the increased nucleation sites provided, their high diffusion rates, reduced sintering time or temperature, and high mechanical properties. The aim of the present work was the evaluation of the effect of different ratios of Ethanol/TEOS and total amount of the inserted ammonia to the particle size, morphology and bioactive, hemolytic and antibacterial behavior of nanoparticles in the quaternary system SiO2-CaO-MgO-CuO. Different ratios of Ethanol/TEOS and ammonia amount affected the size and morphology of bioactive nanopowders. The optimum materials were synthesized with the highest ethanol/TEOS ratio and ammonia amount as verified by the enhanced apatite-forming ability and antibacterial and non-hemolytic properties.
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Affiliation(s)
- Georgia K Pouroutzidou
- School of Physics, Faculty of Sciences, Aristotle University of Thessaloniki, 54124, Thessaloníki, Greece
| | - Georgios S Theodorou
- School of Physics, Faculty of Sciences, Aristotle University of Thessaloniki, 54124, Thessaloníki, Greece
| | - Eleana Kontonasaki
- Department of Fixed Prosthesis and Implant Prosthodontics, School of Health Sciences, Faculty of Dentistry, Aristotle University of Thessaloniki, 54124, Thessaloniki, Greece.
| | - Ioannis Tsamesidis
- Department of Biomedical Sciences, University of Sassari, Sassari, 07100, Italy
| | - Antonella Pantaleo
- Department of Biomedical Sciences, University of Sassari, Sassari, 07100, Italy
| | - Dimitra Patsiaoura
- School of Physics, Faculty of Sciences, Aristotle University of Thessaloniki, 54124, Thessaloníki, Greece
| | - Lambrini Papadopoulou
- Department of Mineralogy-Petrology-Economic Geology, School of Geology, Faculty of Sciences, Aristotle University of Thessaloniki, 54124, Thessaloniki, Greece
| | - Jonathan Rhoades
- Department of Food Technology, Alexander Technological Educational Institute of Thessaloniki, Thessaloniki, 57 400, Greece
| | - Eleni Likotrafiti
- Department of Food Technology, Alexander Technological Educational Institute of Thessaloniki, Thessaloniki, 57 400, Greece
| | - Christos B Lioutas
- School of Physics, Faculty of Sciences, Aristotle University of Thessaloniki, 54124, Thessaloníki, Greece
| | - Konstantinos Chrissafis
- School of Physics, Faculty of Sciences, Aristotle University of Thessaloniki, 54124, Thessaloníki, Greece
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Malletzidou L, Sfampa IK, Kitis G, Paraskevopoulos KM, Polymeris GS. The effect of water on the thermoluminescence properties in various forms of calcium sulfate samples. RADIAT MEAS 2019. [DOI: 10.1016/j.radmeas.2019.01.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Malletzidou L, Zorba TT, Patsiaoura D, Lampakis D, Beinas P, Touli V, Chrissafis K, Karapanagiotis I, Pavlidou E, Paraskevopoulos KM. Unraveling the materials and techniques of post-Byzantine wall paintings: Is there a sole pictorial phase at the catholicon of Stomion, Central Greece? Spectrochim Acta A Mol Biomol Spectrosc 2019; 206:328-339. [PMID: 30145494 DOI: 10.1016/j.saa.2018.07.105] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 07/18/2018] [Accepted: 07/31/2018] [Indexed: 06/08/2023]
Abstract
Saint Demetrius of Stomion is a historical monastery placed in the geographical area of Larissa town, Greece, with a remarkable presence from its founding until nowadays. The monastery's present catholicon (main church) has been dated in the 16th century and its surviving wall paintings were constructed in 1758. In addition to the characterization of the materials applied, the purpose of this study is to determine the existence of a sole pictorial phase, that of the mid-18th century, or the occurrence of overpaintings. Additionally, the present study aims to begin the establishment of the documentation of materials and techniques of the late post-Byzantine iconographic guilds, which acted in Central and Northern Greece. The collected samples were analyzed by means of microscopic, spectroscopic and thermogravimetric methods. The use of fresco technique is implied by the major participation of calcium carbonate in all of the painting layers, its main contribution in the plaster layers and the microstratigraphic analysis of the samples' cross-sections, while the scarce and local presence of a proteinaceous material implies the limited use of egg-tempera technique for the highlights. The pigment analysis shows that mostly traditional pigments were used, including cinnabar, ferrous pigments (ochre, sienna, umber), minium, Naples yellow, massicot/litharge, green earth (celadonite), malachite, carbon and bone black, calcite, kaolinite and lead white. The absence of modern pigments, the consistency of all samples regarding microstratigraphy and applied materials, and the lack of the extensive use of an organic medium, strongly suggest the lack of overpaintings.
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Affiliation(s)
- Lamprini Malletzidou
- School of Physics, Faculty of Sciences, Aristotle University of Thessaloniki, GR54124, Thessaloniki, Greece.
| | - Triantafyllia T Zorba
- School of Physics, Faculty of Sciences, Aristotle University of Thessaloniki, GR54124, Thessaloniki, Greece
| | - Dimitra Patsiaoura
- School of Physics, Faculty of Sciences, Aristotle University of Thessaloniki, GR54124, Thessaloniki, Greece
| | - Dimitrios Lampakis
- University Ecclesiastical Academy of Thessaloniki, Department of Management and Conservation of Ecclesiastical Cultural Heritage Objects, Thessaloniki, Greece; Technological Educational Institute of Thessaly, Larissa, Greece
| | - Pavlos Beinas
- Painting Conservator, 'Esaeitechnon' Artwork Conservation Laboratory, GR60100, Katerini, Greece
| | - Vassiliki Touli
- Ephorate of Antiquities of Larissa, GR41500, Larissa, Greece
| | - Konstantinos Chrissafis
- School of Physics, Faculty of Sciences, Aristotle University of Thessaloniki, GR54124, Thessaloniki, Greece
| | - Ioannis Karapanagiotis
- University Ecclesiastical Academy of Thessaloniki, Department of Management and Conservation of Ecclesiastical Cultural Heritage Objects, Thessaloniki, Greece
| | - Eleni Pavlidou
- School of Physics, Faculty of Sciences, Aristotle University of Thessaloniki, GR54124, Thessaloniki, Greece
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Beketova A, Varitis S, Kontonasaki E, Zorba T, Papadopoulou L, Kantiranis N, Theodorou GS, Paraskevopoulos KM, Koidis P. Evaluation of the micro-mechanical and bioactive properties of bioactive glass-dental porcelain composite. J Mech Behav Biomed Mater 2018; 86:77-83. [PMID: 29957447 DOI: 10.1016/j.jmbbm.2018.06.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 06/08/2018] [Accepted: 06/12/2018] [Indexed: 02/06/2023]
Abstract
The aim of this study was to evaluate microhardness and elastic modulus of a novel sol-gel derived dental ceramic - 58S bioactive glass composite (BP67: Bioactive Glass:33.3%, Dental Ceramic:66.7%) BP671 material by micro-indentation and to investigate its microstructure and bioactivity. The research hypotheses were that the values of microhardness (1) and elastic modulus (2) of the novel bioceramic composite and the commercial dental ceramic will be of the same order. The experimental sol-gel derived ceramics showed similar microstructural characteristics to a commercial feldspathic porcelain, and presence of additional calcium phosphate phases, which contributed its bioactivity. The formation of an apatite-like layer on the materials' surface observed by Fourier Transform Infrared (FTIR)2 spectroscopy, X-ray Diffraction (XRD)3 and Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS)4 techniques after 12 days of maintenance in Conventional Simulated Body Fluid (cSBF)5 solution. The BP67 exhibited values of microhardness and modulus of elasticity which were not statistically significant different compared to dental ceramic, indicating the adequate mechanical integrity of the material. The results of this study suggest that the novel bioactive composite could be potentially applied in prosthetic dentistry, while its thermal and optical properties should be investigated in future studies.
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Affiliation(s)
- Anastasia Beketova
- School of Health Sciences, Dentistry Department, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
| | - Savvas Varitis
- Physics Department, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
| | - Eleana Kontonasaki
- School of Health Sciences, Dentistry Department, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
| | - Triantafillia Zorba
- Physics Department, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
| | - Lambrini Papadopoulou
- Department of Geology, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
| | - Nikolaos Kantiranis
- Department of Geology, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
| | - Georgios S Theodorou
- Physics Department, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
| | | | - Petros Koidis
- School of Health Sciences, Dentistry Department, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece.
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Chatzistavrou X, Lefkelidou A, Papadopoulou L, Pavlidou E, Paraskevopoulos KM, Fenno JC, Flannagan S, González-Cabezas C, Kotsanos N, Papagerakis P. Bactericidal and Bioactive Dental Composites. Front Physiol 2018; 9:103. [PMID: 29503619 PMCID: PMC5820345 DOI: 10.3389/fphys.2018.00103] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Accepted: 01/31/2018] [Indexed: 11/13/2022] Open
Abstract
Aim: Antimicrobial and bioactive restorative materials are needed to develop a bacteria free environment and tight bond with the surrounding tissue, preventing the spread of secondary caries and thus extending the lifetime of dental restorations. The characteristic properties of new dental bioactive and antibacterial composites are presented in this work. The new composites have been microstructurally characterized and both long and short term properties have been studied. Methods: The Ag-doped sol-gel derived bioactive glass (Ag-BG) was incorporated into resin composite in concentrations 5, 10, and 15 wt.%, to fabricate new Ag-doped bioactive and antibacterial dental composites (Ag-BGCOMP). The microstructural properties and elemental analysis of the developed Ag-BGCOMP was observed. The total bond strength (TBS) was measured immediately and after long term of immersion in medium using microtensile testing. The capability of Ag-BGCOMPs to form apatite layer on their surface after immersion in Simulated Body Fluid (SBF) as well as the bacteria growth inhibition in a biofilm formed by Streptococcus mutans (S. mutans) were evaluated. Results: Homogeneous distribution of Ag-BG particles into the resin composite was observed microstructurally for all Ag-BGCOMPs. The TBS measurements showed non-statistically significant difference between control samples (Ag-BG 0 wt.%) and Ag-BGCOMP specimens. Moreover, the total bond strength between the surrounding tooth tissue and the material of restoration does not present any statistically significant change for all the cases even after 3 months of immersion in the medium. The bioactivity of the Ag-BGCOMPs was also shown by the formation of a calcium-phosphate layer on the surface of the specimens after immersion in SBF. Antibacterial activity was observed for all Ag-BGCOMPs, statistically significant differences were observed between control samples and Ag-BGCOMPs. Accordingly, the number of dead bacteria in the biofilm found to increase significantly with the increase of Ag-BG concentration in the Ag-BGCOMPs. Conclusions: New resin composites with antibacterial and remineralizing properties have been manufactured. Characterization of these materials provides a rationale for future clinical trials to evaluate clinical benefits and outcomes in comparison with currently used dental materials. Significance: The new developed composites could ultimately prevent restoration failure and could advance patients' wellbeing.
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Affiliation(s)
- Xanthippi Chatzistavrou
- Department of Orthodontics and Pediatric Dentistry, University of Michigan, Ann Arbor, MI, United States
| | - Anna Lefkelidou
- Department of Orthodontics and Pediatric Dentistry, University of Michigan, Ann Arbor, MI, United States.,Department of Pediatric Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | | | - Eleni Pavlidou
- Physics Department, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | | | - J Christopher Fenno
- Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, MI, United States
| | - Susan Flannagan
- Cariology, Restorative Sciences and Endodontics, University of Michigan, Ann Arbor, MI, United States
| | - Carlos González-Cabezas
- Cariology, Restorative Sciences and Endodontics, University of Michigan, Ann Arbor, MI, United States
| | - Nikos Kotsanos
- Department of Pediatric Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Petros Papagerakis
- Department of Orthodontics and Pediatric Dentistry, University of Michigan, Ann Arbor, MI, United States
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Pandoleon P, Kontonasaki E, Kantiranis N, Pliatsikas N, Patsalas P, Papadopoulou L, Zorba T, Paraskevopoulos KM, Koidis P. Aging of 3Y-TZP dental zirconia and yttrium depletion. Dent Mater 2017; 33:e385-e392. [PMID: 28789858 DOI: 10.1016/j.dental.2017.07.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 05/03/2017] [Accepted: 07/11/2017] [Indexed: 02/04/2023]
Abstract
OBJECTIVE Yttrium-stabilized zirconia is susceptible to low temperature degradation after interaction with water. Various mechanisms by which water molecules destabilize the tetragonal phase have been proposed, while the concept of yttrium depletion by the incorporation of hydroxyl ions in the crystalline structure either through the formation of YOH/ZrOH bonds or small α-Y(OH)3 crystallites, is prevailing. The present study was performed to investigate the surface alterations on a 3Y-TZP dental ceramic during the process of in-vitro aging and to further explore the yttrium depletion mechanism that occurs upon interaction with water. METHODS Surface structural changes of zirconia specimens where investigated before and after in-vitro aging with X-ray diffraction analysis, Fourier-transformed infrared spectroscopy, X-ray photoelectron spectroscopy, fluorescence microscopy and scanning electron microscopy. RESULTS High luminescence generated from the non-aged specimen was explained by the high amount of oxygen vacancies. The phase transformation from the t-ZrO2 to the m-ZrO2 phase after aging was accompanied by a significant loss of yttrium, a clear decrease of oxygen vacancies and a profound decrease of luminescence. Surface oxygen vacancies either migrated into the inner of the specimens or/and/engaged oxygen from the ZrO2 and formed the metallic phase of Y2O3 on the surface after aging. SIGNIFICANCE An "ideal" amount of oxygen vacancies that could stabilize the tetragonal phase in Y-TZP zirconia ceramics, without compromising esthetics and LTD resistance, is still a matter of further research and different susceptibilities to LTD among various dental zirconia ceramics are based on the amount of oxygen vacancies that can be annihilated by water molecules.
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Affiliation(s)
- P Pandoleon
- Faculty of Dentistry, Department of Prosthodontics, School of Health Sciences, Aristotle University of Thessaloniki, GR-54124, Thessaloniki, Greece
| | - E Kontonasaki
- Faculty of Dentistry, Department of Prosthodontics, School of Health Sciences, Aristotle University of Thessaloniki, GR-54124, Thessaloniki, Greece
| | - N Kantiranis
- Department of Mineralogy-Petrology-Economic Geology, Aristotle University of Thessaloniki, GR-54124, Thessaloniki, Greece
| | - N Pliatsikas
- Department of Physics, Aristotle University of Thessaloniki, GR-54124, Thessaloniki, Greece
| | - P Patsalas
- Department of Physics, Aristotle University of Thessaloniki, GR-54124, Thessaloniki, Greece
| | - L Papadopoulou
- Department of Mineralogy-Petrology-Economic Geology, Aristotle University of Thessaloniki, GR-54124, Thessaloniki, Greece
| | - T Zorba
- Department of Physics, Aristotle University of Thessaloniki, GR-54124, Thessaloniki, Greece
| | - K M Paraskevopoulos
- Department of Physics, Aristotle University of Thessaloniki, GR-54124, Thessaloniki, Greece
| | - P Koidis
- Faculty of Dentistry, Department of Prosthodontics, School of Health Sciences, Aristotle University of Thessaloniki, GR-54124, Thessaloniki, Greece.
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Goudouri OM, Kontonasaki E, Papadopoulou L, Manda M, Kavouras P, Triantafyllidis KS, Stefanidou M, Koidis P, Paraskevopoulos KM. An experimental bioactive dental ceramic for metal-ceramic restorations: Textural characteristics and investigation of the mechanical properties. J Mech Behav Biomed Mater 2016; 66:95-103. [PMID: 27842244 DOI: 10.1016/j.jmbbm.2016.10.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 10/19/2016] [Accepted: 10/26/2016] [Indexed: 11/17/2022]
Abstract
The aim of this study was the evaluation of the textural characteristics of an experimental sol-gel derived feldspathic dental ceramic, which has already been proven bioactive and the investigation of its flexural strength through Weibull Statistical Analysis. The null hypothesis was that the flexural strength of the experimental and the commercial dental ceramic would be of the same order, resulting in a dental ceramic with apatite forming ability and adequate mechanical integrity. Although the flexural strength of the experimental ceramics was not statistically significant different compared to the commercial one, the amount of blind pores due to processing was greater. The textural characteristics of the experimental ceramic were in accordance with the standard low porosity levels reported for dental ceramics used for fixed prosthetic restorations. Feldspathic dental ceramics with typical textural characteristics and advanced mechanical properties as well as enhanced apatite forming ability can be synthesized through the sol-gel method.
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Affiliation(s)
| | - Eleana Kontonasaki
- School of Health Sciences, Dentistry Department, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Lambrini Papadopoulou
- Department of Geology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Marianthi Manda
- School of Health Sciences, Dentistry Department, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Panagiotis Kavouras
- Research center of Advanced Unit Composites, Nano Materials and Nanotechnology, Department of Materials Science and Engineering, School of Chemical Engineering, National Technical University, Athens GR-157 80, Greece
| | | | - Maria Stefanidou
- Department of Civil Engineering, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Petros Koidis
- School of Health Sciences, Dentistry Department, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
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Beketova A, Poulakis N, Bakopoulou A, Zorba T, Papadopoulou L, Christofilos D, Kantiranis N, Zachariadis GA, Kontonasaki E, Kourouklis GA, Paraskevopoulos KM, Koidis P. Inducing bioactivity of dental ceramic/bioactive glass composites by Nd:YAG laser. Dent Mater 2016; 32:e284-e296. [PMID: 27682895 DOI: 10.1016/j.dental.2016.09.029] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 07/01/2016] [Accepted: 09/03/2016] [Indexed: 11/28/2022]
Abstract
OBJECTIVES Aims of this study were to investigate the optimal conditions of laser irradiation of a novel Bioactive Glass/Dental Ceramic-BP67 composite for acceleration of hydroxyapatite-HA formation and to assess cellular responses on the precipitated HA region. METHODS BP67 (Bioactive Glass: 33.3%, Dental Ceramic: 66.7%) was fabricated by the sol-gel method. A laser assisted biomimetic-LAB process was applied to BP67 sintered specimens immersed in 1.5-times concentrated simulated body fluid-1.5×-SBF. The effect of various energy densities of pulsed nanosecond Nd-YAG (1064nm) laser and irradiation exposure times (30min, 1 and 3h) were evaluated for HA precipitation. The HA film was characterized by FTIR, XRD, SEM and micro Raman techniques. ICP-AES was used for revealing changes in chemical composition of the 1.5×-SBF during irradiation. Cell viability and morphological characteristics of periodontal ligament fibroblasts-PDLFs, human gingival fibroblasts-HGFs and SAOS-2 osteoblasts on the HA surface were evaluated by MTT assays and SEM. RESULTS At optimal energy fluence of 1.52J/cm2 and irradiation time for 3h followed by immersion in 1.5×-SBF at 60°C, a dense HA layer was formed on laser-irradiated BP67 within 7 days. The resulting HA film was tightly bonded to the underlying substrate and had mineral composition similar to cementum. MTT assay showed a consistent reduction of cell proliferation on the HA layer in comparison to conventional control ceramic and BP67 for all 3 cell lines studied. SIGNIFICANCE These findings suggest LAB is an effective method for acceleration of HA formation on materials with low bioactivity, while cellular responses need further investigation.
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Affiliation(s)
- Anastasia Beketova
- Department of Fixed Prosthesis and Implant Prosthodontics, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki GR-54124, Greece
| | - Nikolaos Poulakis
- Department of Electrical Engineering, Technological Educational Institute of Western Macedonia, Koila, 50100 Kozani, Greece
| | - Athina Bakopoulou
- Department of Fixed Prosthesis and Implant Prosthodontics, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki GR-54124, Greece
| | - Triantafillia Zorba
- Physics Department, Aristotle University of Thessaloniki, Thessaloniki GR-54124, Greece
| | - Lambrini Papadopoulou
- School of Geology, Aristotle University of Thessaloniki, Thessaloniki GR-54124, Greece
| | - Dimitrios Christofilos
- Department of Chemical Engineering, School of Engineering, Aristotle University of Thessaloniki, Thessaloniki GR-54124, Greece
| | - Nikolaos Kantiranis
- School of Geology, Aristotle University of Thessaloniki, Thessaloniki GR-54124, Greece
| | - George A Zachariadis
- Department of Chemistry, Aristotle University of Thessaloniki, Thessaloniki GR-54124, Greece
| | - Eleana Kontonasaki
- Department of Fixed Prosthesis and Implant Prosthodontics, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki GR-54124, Greece
| | - Gerasimos A Kourouklis
- Department of Chemical Engineering, School of Engineering, Aristotle University of Thessaloniki, Thessaloniki GR-54124, Greece
| | | | - Petros Koidis
- Department of Fixed Prosthesis and Implant Prosthodontics, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki GR-54124, Greece.
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Theodorou GS, Kontonasaki E, Theocharidou A, Bakopoulou A, Bousnaki M, Hadjichristou C, Papachristou E, Papadopoulou L, Kantiranis NA, Chrissafis K, Paraskevopoulos KM, Koidis PT. Sol-Gel Derived Mg-Based Ceramic Scaffolds Doped with Zinc or Copper Ions: Preliminary Results on Their Synthesis, Characterization, and Biocompatibility. Int J Biomater 2016; 2016:3858301. [PMID: 26981124 PMCID: PMC4769780 DOI: 10.1155/2016/3858301] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 01/11/2016] [Indexed: 12/22/2022] Open
Abstract
Glass-ceramic scaffolds containing Mg have shown recently the potential to enhance the proliferation, differentiation, and biomineralization of stem cells in vitro, property that makes them promising candidates for dental tissue regeneration. An additional property of a scaffold aimed at dental tissue regeneration is to protect the regeneration process against oral bacteria penetration. In this respect, novel bioactive scaffolds containing Mg(2+) and Cu(2+) or Zn(2+), ions known for their antimicrobial properties, were synthesized by the foam replica technique and tested regarding their bioactive response in SBF, mechanical properties, degradation, and porosity. Finally their ability to support the attachment and long-term proliferation of Dental Pulp Stem Cells (DPSCs) was also evaluated. The results showed that conversely to their bioactive response in SBF solution, Zn-doped scaffolds proved to respond adequately regarding their mechanical strength and to be efficient regarding their biological response, in comparison to Cu-doped scaffolds, which makes them promising candidates for targeted dental stem cell odontogenic differentiation and calcified dental tissue engineering.
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Affiliation(s)
- Georgios S. Theodorou
- Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Eleana Kontonasaki
- Dentistry Department, Laboratory of Fixed Prosthesis and Implant Prosthodontics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Anna Theocharidou
- Dentistry Department, Laboratory of Fixed Prosthesis and Implant Prosthodontics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Athina Bakopoulou
- Dentistry Department, Laboratory of Fixed Prosthesis and Implant Prosthodontics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Maria Bousnaki
- Dentistry Department, Laboratory of Fixed Prosthesis and Implant Prosthodontics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Christina Hadjichristou
- Dentistry Department, Laboratory of Fixed Prosthesis and Implant Prosthodontics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Eleni Papachristou
- Dentistry Department, Laboratory of Fixed Prosthesis and Implant Prosthodontics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Lambrini Papadopoulou
- Department of Geology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | | | | | | | - Petros T. Koidis
- Dentistry Department, Laboratory of Fixed Prosthesis and Implant Prosthodontics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
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Siarampi E, Kontonasaki E, Andrikopoulos KS, Kantiranis N, Voyiatzis GA, Zorba T, Paraskevopoulos KM, Koidis P. Effect of in vitro aging on the flexural strength and probability to fracture of Y-TZP zirconia ceramics for all-ceramic restorations. Dent Mater 2014; 30:e306-16. [PMID: 24993809 DOI: 10.1016/j.dental.2014.05.033] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 11/17/2013] [Accepted: 05/29/2014] [Indexed: 02/04/2023]
Abstract
OBJECTIVES Dental zirconia restorations should present long-term clinical survival and be in service within the oral environment for many years. However, low temperature degradation could affect their mechanical properties and survival. The aim of this study was to investigate the effect of in vitro aging on the flexural strength of yttrium-stabilized (Y-TZP) zirconia ceramics for ceramic restorations. METHODS One hundred twenty bar-shaped specimens were prepared from two ceramics (ZENO Zr (WI) and IPS e.max(®) ZirCAD (IV)), and loaded until fracture according to ISO 6872. The specimens from each ceramic (nx=60) were divided in three groups (control, aged for 5h, aged for 10h). One-way ANOVA was used to assess statistically significant differences among flexural strength values (P<0.05). The variability of the flexural strength values was analyzed using the two-parameter Weibull distribution function, which was applied for the estimation of Weibull modulus (m) and characteristic strength (σ0). The crystalline phase polymorphs of the materials (tetragonal, t, and monoclinic, m, zirconia) were investigated by X-ray diffraction (XRD) analysis, Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy. RESULTS A slight increase of the flexural strength after 5h, and a decrease after 10h of aging, was recorded for both ceramics, however statistically significant was for the WI group (P<0.05). Both ceramics presented a t→m phase transformation, with the m-phase increasing from 4 to 5% at 5h to around 15% after 10h. SIGNIFICANCE The significant reduction of the flexural strength after 10h of in vitro aging, suggests high fracture probability for one of the zirconia ceramics tested.
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Affiliation(s)
- Eleni Siarampi
- Department of Fixed Prosthesis and Implants Prosthodontics, School of Dentistry, Aristotle University of Thessaloniki, GR 54124, Thessaloniki, Greece
| | - Eleana Kontonasaki
- Department of Fixed Prosthesis and Implants Prosthodontics, School of Dentistry, Aristotle University of Thessaloniki, GR 54124, Thessaloniki, Greece
| | - Konstantinos S Andrikopoulos
- Foundation for Research and Technology Hellas - Institute of Chemical Engineering Sciences (FORTH-ICE/HT), P.O. Box 1414, GR 26504, Rio - Patras, Greece
| | - Nikolaos Kantiranis
- Department of Geology, Aristotle University of Thessaloniki, GR 54124, Thessaloniki, Greece
| | - George A Voyiatzis
- Foundation for Research and Technology Hellas - Institute of Chemical Engineering Sciences (FORTH-ICE/HT), P.O. Box 1414, GR 26504, Rio - Patras, Greece
| | - Triantafillia Zorba
- Physics Department, Aristotle University of Thessaloniki, GR 54124, Thessaloniki, Greece
| | | | - Petros Koidis
- Department of Fixed Prosthesis and Implants Prosthodontics, School of Dentistry, Aristotle University of Thessaloniki, GR 54124, Thessaloniki, Greece.
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Siarampi E, Kontonasaki E, Papadopoulou L, Kantiranis N, Zorba T, Paraskevopoulos KM, Koidis P. Flexural strength and the probability of failure of cold isostatic pressed zirconia core ceramics. J Prosthet Dent 2012; 108:84-95. [DOI: 10.1016/s0022-3913(12)60112-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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Chatzistavrou X, Kontonasaki E, Bakopoulou A, Theocharidou A, Sivropoulou A, Paraskevopoulos KM, Koidis P, Boccaccini AR, Kasuga T. Development of new sol-gel derived Ag-doped biomaterials for dental applications. ACTA ACUST UNITED AC 2012. [DOI: 10.1557/opl.2012.743] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTThe aim of this work was to develop a new Ag-doped bioactive material with antibacterial behavior, optimizing the properties of the new fabricated composite material in the system SiO2 58.6 -P2O5 7.2 -Al2O3 4.2 -CaO 24.9 -Na2O 2.1 -K2O 3 (wt%). Two systems with different concentrations in Ag2O (Ba with 2.1 and Bb with 4.2 wt%) were prepared by the sol-gel method and compared to the respective silver-free control composite (CONTROL). The microstructural characteristics of the developed compositions were characterized by different techniques as UV/VIS spectroscopy, X-ray diffraction analysis (XRD) and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS). The antibacterial properties of the Ag-doped glass-ceramics were tested against the bacterial colony Staphylococcus aureus (S. aureus) which is very characteristic oral bacteria and the material-cell interaction was monitored in a primary culture of Human Gingival Fibroblasts (HGFs). Our study shows the successful incorporation of the silver ions in the ceramic structure and the preparation of new Ag-doped composite materials with cell-proliferation-inductive, as well as antibacterial properties indicating their potential application dental tissue restoration strategies.
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Chung I, Biswas K, Song JH, Androulakis J, Chondroudis K, Paraskevopoulos KM, Freeman AJ, Kanatzidis MG. Rb4Sn5P4Se20: A Semimetallic Selenophosphate. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201104050] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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17
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Chung I, Biswas K, Song JH, Androulakis J, Chondroudis K, Paraskevopoulos KM, Freeman AJ, Kanatzidis MG. Rb4Sn5P4Se20: A Semimetallic Selenophosphate. Angew Chem Int Ed Engl 2011; 50:8834-8. [DOI: 10.1002/anie.201104050] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Indexed: 11/12/2022]
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Hasapis TC, Girard SN, Hatzikraniotis E, Paraskevopoulos KM, Kanatzidis MG. Infrared Studies of the (1-x) PbTe – (x) PbSnS2 System. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/opl.2011.848] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTIn this work we report on the infrared properties of the thermoelectric (1-x)PbTe-xPbSnS2 system with x=0.03, 0.06, 0.11 and 0.33. The results obtained by the analysis of the reflectivity spectra are discussed together with the structural and morphological characteristics obtained by XRD and SEM-EDS measurements. The system was found macroscopically homogeneous for x=0.03 and x=0.06 and phase separated for x=0.11 and x=0.33. The analyzed ~150cm-1 PbS impurity mode demonstrated a composition close to the PbTe0.98S0.02 for the major phase. The incorporation of PbSnS2 causes a reduction in plasma frequency (decrease in carrier frequency concentration) and an increase in carrier mobility.
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Zorbas K, Hatzikraniotis E, Paraskevopoulos KM. Power and Efficiency Calculation and Evaluation of Material Properties in Thermoelectric Power Generators. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-1044-u09-15] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AbstractThermoelectric elements convert a part of thermal power into electrical, developing the Seebeck effect. A number of thermoelectric elements can be connected electrically in parallel and/or in series shaping a thermoelectric generator (TEG) device. The generator efficiency, η, is determined by comparing the amount of electricity produced (PTEG) to the total amount of heat induced (QH). The possible use of such a device for the recovery of wasted heat can considerably help the world effort for energy savings and the reduction of greenhouse gases.A measuring system and a modeling approach which takes into account the thermal contact resistances have been developed, allowing the characterization of TEG devices under various loads and temperature gradients and thus, the evaluation of material properties. The model was applied on investigating the expected gained power and efficiency, at different places of the exhaust pipe of an intermediate size car with the use of conventional thermoelectric elements. Furthermore, the reliability of a TEG module was examined and the repercussion on fuel consumption is discussed.
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Hasapis TC, Papageorgiou C, Hatzikraniotis E, Kyratsi T, Paraskevopoulos KM. IR Reflectivity Studies of Mechanically Alloyed PbTe Nanocrystals. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-1166-n03-12] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AbstractNano-crystalline lead telluride powder was synthesized by mechanical alloying using a high-energy planetary ball mill. The broadening of the X-ray diffraction peaks vs ball milling time, indicates small crystalline size of the order of 30nm. IR spectroscopy results are discussed and compared to the material prepared from melt.
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Matsou E, Vouroutzis N, Kontonasaki E, Paraskevopoulos KM, Koidis P. Investigation of the influence of gastric acid on the surface roughness of ceramic materials of metal-ceramic restorations. An in vitro study. INT J PROSTHODONT 2011; 24:26-29. [PMID: 21209998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The rehabilitation of eroded teeth in patients suffering from bulimia nervosa generally includes ceramics. This study compared the roughness of three ceramics before and after exposure to simulated vomit solution (SVS) with a pH of 3.8. Surface roughness parameters Ra, RMS, and AH were calculated using atomic force microscopy before and after exposure to SVS (novel peristaltic pump for 24 hours at 37°C) and were analyzed statistically. Apart from the initial high AH values of the glass-ceramic, none of the parameters evaluated were statistically significantly different after acid exposure. Under the limitations of this in vitro study, the investigated ceramics seem suitable for use in bulimia nervosa patients.
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Affiliation(s)
- Eirini Matsou
- Department of Fixed Prosthesis and Implant Prosthodontics, Aristotle University of Thessaloniki, Thessaloniki, Greece
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Chrissafis K, Paraskevopoulos KM, Papageorgiou GZ, Bikiaris DN. Thermal and dynamic mechanical behavior of bionanocomposites: Fumed silica nanoparticles dispersed in poly(vinyl pyrrolidone), chitosan, and poly(vinyl alcohol). J Appl Polym Sci 2008. [DOI: 10.1002/app.28818] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Androulakis J, Lin CH, Kong HJ, Uher C, Wu CI, Hogan T, Cook BA, Caillat T, Paraskevopoulos KM, Kanatzidis MG. Spinodal decomposition and nucleation and growth as a means to bulk nanostructured thermoelectrics: enhanced performance in Pb(1-x)Sn(x)Te-PbS. J Am Chem Soc 2007; 129:9780-8. [PMID: 17629270 DOI: 10.1021/ja071875h] [Citation(s) in RCA: 387] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The solid-state transformation phenomena of spinodal decomposition and nucleation and growth are presented as tools to create nanostructured thermoelectric materials with very low thermal conductivity and greatly enhanced figure of merit. The systems (PbTe)(1-x)(PbS)(x) and (Pb(0.95)Sn(0.05)Te)(1-x)(PbS)(x) are not solid solutions but phase separate into PbTe-rich and PbS-rich regions to produce coherent nanoscale heterogeneities that severely depress the lattice thermal conductivity. For x > approximately 0.03 the materials are ordered on three submicrometer length scales. Transmission electron microscopy reveals both spinodal decomposition and nucleation and growth phenomena the relative magnitude of which varies with x. We show that the (Pb(0.95)Sn(0.05)Te)(1-x)(PbS)(x) system, despite its nanostructured nature, maintains a high electron mobility (>100 cm(2)/V x s at 700 K). At x approximately 0.08 the material achieves a very low room-temperature lattice thermal conductivity of approximately 0.4 W/m x K. This value is only 28% of the PbTe lattice thermal conductivity at room temperature. The inhibition of heat flow in this system is caused by nanostructure-induced acoustic impedance mismatch between the PbTe-rich and PbS-rich regions. As a result the thermoelectric properties of (Pb(0.95)Sn(0.05)Te)(1-x)(PbS)(x) at x = 0.04, 0.08, and 0.16 were found to be superior to those of PbTe by almost a factor of 2. The relative importance of the two observed modes of nanostructuring, spinodal decomposition and nucleation and growth, in suppressing the thermal conductivity was assessed in this work, and we can conclude that the latter mode seems more effective in doing so. The promise of such a system for high efficiency is highlighted by a ZT approximately 1.50 at 642 K for x approximately 0.08.
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Affiliation(s)
- John Androulakis
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA
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Zorba T, Andrikopoulos KS, Paraskevopoulos KM, Pavlidou E, Popkonstantinov K, Kostova R, Platnyov V, Daniilia S. Infrared and Raman Vibrational Spectroscopies Reveal the Palette of Frescos Found in the Medieval Monastery of Karaach Teke. ACTA ACUST UNITED AC 2007; 97:491-503. [PMID: 17867534 DOI: 10.1002/adic.200790032] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Vibrational spectroscopy is applied on samples obtained from the excavation area of the medieval Monastery (10th century) of Karaach-Teke in Bulgaria. The results of the corresponding study, reveal the type of materials used for the creation of the wall-paintings and give evidence of Byzantine influence, a fact that further supports the well known impact of Byzantium on the technology and thematic-aesthetic features of iconography in Bulgaria during this era. In addition, the complementarity of FTIR and micro-Raman spectroscopies in the identification of pigments is indicated.
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Affiliation(s)
- T Zorba
- Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
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