Τμήμα Επιστήμης & Μηχανικής Υλικών
12 Ιουλίου 2024
Πρόσκληση σε Δημόσια Παρουσίαση της Διδακτορικής Διατριβής της
κ. Γεωργίας- Ιωάννας Κοντογιάννη
Επιβλέπουσα Καθηγήτρια: Μαρία Χατζηνικολαΐδου
(Σύμφωνα με το άρθρο 95, παρ. 3 του Ν. 4957/2022, ΦΕΚ 141 τ. Α΄/21.7.2022)
Την Πέμπτη 18 Ιουλίου 2024 και ώρα 12:00 στην αίθουσα Τηλεκπαίδευσης Ε130 του Τμήματος Μαθηματικών και Εφαρμοσμένων Μαθηματικών του Πανεπιστημίου Κρήτης, θα γίνει η δημόσια παρουσίαση και υποστήριξη της Διδακτορικής Διατριβής της υποψήφιας διδάκτορος του Τμήματος Επιστήμης και Μηχανικής Υλικών κ. Γεωργίας- Ιωάννας Κοντογιάννη, με θέμα:
«Evaluation of the Osteogenic and Osteoclastogenic Potential of Cell Mono- and Co-Cultures in 3D Printed Composite Scaffolds Under Dynamic Conditions»
Περίληψη
Bone tissue engineering (BTE) leverages cutting-edge technologies like 3D printing, specifically fused deposition modeling (FDM), to create scaffolds that mimic the native bone tissue. FDM allows for the creation of complex, patient-specific scaffolds with customizable porosity and mechanical properties. Integrating osteoinductive compounds such as nano-hydroxyapatite (nHA) and Sr-substituted nHA (Sr-nHA) into the scaffolds leads to enhanced osteogenic differentiation and bone regeneration capacity. Conventional in vitro evaluation methods typically use cell mono-culture models with osteoblasts or osteoclasts, which fail to replicate the full interactions of the native bone tissue. Co-culture models involving osteoblasts and osteoclasts provide a more accurate representation of natural bone remodeling. Mechanical stimulation in these models is crucial for recreating the mechanical environment of bone and promoting vital cellular activities. This thesis aimed to develop a growth factor-free co-culture system using human bone marrow mesenchymal stem cells (hBM-MSCs) and human peripheral blood mononuclear cells (hPBMCs) under dynamic conditions to evaluate their osteogenic and osteoclastogenic potential within 3D composite scaffolds made of PLLA/PCL/PHBV and nHA or Sr-nHA. As immunomodulation is critical to predict the pre- or anti-inflammatory responses of cells and the possible outcome of scaffolds prior implantation, the immunomodulatory properties of these scaffolds were investigated using macrophages under dynamic culture conditions. The results showed that Sr-nHA scaffolds enhanced osteogenesis and suppressed osteoclastogenesis in a supplement-free co-culture system. Mechanical stimulation further increased osteogenesis and suppressed osteoclastogenesis, and macrophage polarization indicated a stronger anti-inflammatory response after mechanical stimulation.
04 Ιουλίου 2024
ΠΑΝΕΠΙΣΤΗΜΙΟ ΚΡΗΤΗΣ
ΤΜΗΜΑ ΕΠΙΣΤΗΜΗΣ ΚΑΙ ΜΗΧΑΝΙΚΗΣ ΥΛΙΚΩΝ
ΠΑΡΟΥΣΙΑΣΗ ΜΕΤΑΠΤΥΧΙΑΚΗΣ ΔΙΠΛΩΜΑΤΙΚΗΣ ΕΡΓΑΣΙΑΣ
Τίτλος
«Growth of TiO2, NiO Thin Films for Gas Sensing Applications»
του Αλέξανδρου Παπαδάκη
μεταπτυχιακού φοιτητή του Τμήματος Επιστήμης και Μηχανικής Υλικών του Πανεπιστημίου Κρήτης
Επιβλέπων Καθηγητής: Νικόλαος Πελεκάνος
Πέμπτη 11 Ιουλίου 2024, Ώρα 12:30
H παρουσίαση θα πραγματοποιηθεί στην αίθουσα Τηλε-εκπαίδευσης (Ε130), στο κτήριο του Τμήματος Μαθηματικών και Εφαρμοσμένων Μαθηματικών, του Πανεπιστημίου Κρήτης
Abstract
The scope of this Master Thesis work was to fabricate TiO2 and NiO-based sensors in order to detect hazardous gases, such as Ammonia (NH3) and Nitric Oxide (NO), as well as to study the interactions between the single gas molecules and the surface of the thin film. In addition, the sensors were tested against energy related gases, such as Hydrogen (H2) and Methane (CH4), due to the strong interest on the former as green fuel, while the latter one is the main ingredient of natural gas. More specifically TiO2 showed significant response in Hydrogen as well as in Methane gases at elevated temperatures of about 350°C. Additionally, NiO gas sensors were sensitive to Hydrogen, Nitric Oxide and Methane gases. NiO showed results at elevated temperatures and room temperature as well. Finally, the Metal Oxide gas Sensors (MOS) were optically and structurally characterized.01 Ιουλίου 2024
ΠΑΝΕΠΙΣΤΗΜΙΟ ΚΡΗΤΗΣ
ΤΜΗΜΑ ΕΠΙΣΤΗΜΗΣ ΚΑΙ ΜΗΧΑΝΙΚΗΣ ΥΛΙΚΩΝ
ΠΑΡΟΥΣΙΑΣΗ ΜΕΤΑΠΤΥΧΙΑΚΗΣ ΔΙΠΛΩΜΑΤΙΚΗΣ ΕΡΓΑΣΙΑΣ
Τίτλος
«Colloidal Gels Tuned by Magnetic Field»
του Εμμανουήλ Μαθιουδάκη
μεταπτυχιακού φοιτητή του Τμήματος Επιστήμης και Μηχανικής Υλικών του Πανεπιστημίου Κρήτης
Επιβλέπων Καθηγητής: Γεώργιος Πετεκίδης
Τρίτη 2 Ιουλίου 2024, Ώρα 12:00
H παρουσίαση θα πραγματοποιηθεί στην αίθουσα Τηλε-εκπαίδευσης (Ε130), στο κτήριο του Τμήματος Μαθηματικών και Εφαρμοσμένων Μαθηματικών, του Πανεπιστημίου Κρήτης
Abstract
Colloidal gels are materials ubiquitous in everyday life. They are defined as functional materials that may exhibit solid-like properties through the formation of space spanning networks with rich structural and rheological properties. Magnetorheological Fluids (MRFs) are a class of smart colloidal materials, with a variety of applications, such as shock absorbers, that upon the application of an external magnetic field, exhibit a rapid and reversible transition from liquids to soft yield stress solids with columnar and ring structures being formed. Their mechanical properties and microstructure can be studied with the use of rheology and optical microscopy/imaging or scattering. Fumed silica particles have been used in many industry applications such as raw materials for the effects of purity composition in optical fibers, in high strength concrete, as rheological additives for anti-sedimentation, thixotropic and thickening agents in agrochemicals, battery gels, drilling fluids, foods etch, and as filler material for scratch resistance, low thermal conductivity, reinforcement in sealants coatings, insulation and many more. They function as effective thickening and thixotropic agents that can stabilize and modify the rheological response of a variety of systems, while based on the grade of fumed silica, hydrophobic or hydrophilic, and the chemical nature of the solvent, polar or non-polar, can form stable sols or gels with space-filling network and varying mechanical properties. By combining these two classes of materials we create a colloidal gel mixture to probe the rheological behavior and structure formation of the magnetic particles inside the fumed silica suspensions (gels or sols). Moreover, the mechanical properties of the fumed silica suspensions can also be tuned using both mechanical and magnetic stimuli or their combination. Utilizing a powerful combination of in-situ Rheometry and optical imaging, via a rheo-imaging setup, we can apply external magnetic fields and follow the rheological response and some of the microstructural changes of these mixtures under an external magnetic field.
25 Ιουνίου 2024
ΠΑΝΕΠΙΣΤΗΜΙΟ ΚΡΗΤΗΣ
ΤΜΗΜΑ ΕΠΙΣΤΗΜΗΣ ΚΑΙ ΜΗΧΑΝΙΚΗΣ ΥΛΙΚΩΝ
ΠΑΡΟΥΣΙΑΣΗ ΜΕΤΑΠΤΥΧΙΑΚΗΣ ΔΙΠΛΩΜΑΤΙΚΗΣ ΕΡΓΑΣΙΑΣ
Τίτλος
«Structure and Dynamic Properties of Collagen-Based Hydrogels»
της Κωνσταντίνας Λυρώνη
μεταπτυχιακής φοιτήτριας του Τμήματος Επιστήμης και Μηχανικής Υλικών του Πανεπιστημίου Κρήτης
Επιβλέπων Καθηγητής: Δημήτριος Βλασσόπουλος
Πέμπτη 27 Ιουνίου 2024
Ώρα 11:00
H παρουσίαση θα πραγματοποιηθεί στην αίθουσα Τηλε-εκπαίδευσης (Ε130), στο κτήριο του Τμήματος Μαθηματικών και Εφαρμοσμένων Μαθηματικών, του Πανεπιστημίου Κρήτης
Abstract
Collagen type I, the most abundant protein in mammals, due to the unique mechanochemical properties that exhibits, is widely used in the production of porous scaffolds via lyophilization for biomedical applications. To optimize its utilization, a deeper understanding of the link between structure and rheological properties of collagen suspensions is necessary. In this work, we explored the morphology of fibrillar collagen suspensions via confocal fluorescence microscopy and determined the characteristics of the networks such as the mesh size and the fiber diameter. For the investigation of their rheological response, because of the size of the fibers, we tested both cone-plate and parallel plate geometries and examined the possibility of confinement effects, as well as the effects of loading. Furthermore, we studied the effects of the loading history of the collagen suspension. The experimental results reveal shear thinning and a small yield stress, as well as the presence of wall slip. The latter is evidence in the preliminary data of Particle Image Velocimetry (PIV). Analysis of the viscoelastic properties of the suspension yielded a mesh size in the entangled regime, using different models that have been used to describe similar systems. The agreement with the confocal microscopy data is encouraging.25 Ιουνίου 2024
ΠΑΝΕΠΙΣΤΗΜΙΟ ΚΡΗΤΗΣ
ΤΜΗΜΑ ΕΠΙΣΤΗΜΗΣ ΚΑΙ ΜΗΧΑΝΙΚΗΣ ΥΛΙΚΩΝ
ΠΑΡΟΥΣΙΑΣΗ ΜΕΤΑΠΤΥΧΙΑΚΗΣ ΔΙΠΛΩΜΑΤΙΚΗΣ ΕΡΓΑΣΙΑΣ
Τίτλος
«Cs2AgBiBr6 Perovskites & 2D Material Conjugations for Gas Sensing Applications»
της Μαρίας Συσκάκη
μεταπτυχιακής φοιτήτριας του Τμήματος Επιστήμης και Μηχανικής Υλικών του Πανεπιστημίου Κρήτης
Επιβλέπων: Εμμανουήλ Στρατάκης
Πέμπτη 27 Ιουνίου 2024, Ώρα 13:00
H παρουσίαση θα πραγματοποιηθεί στην αίθουσα Τηλε-εκπαίδευσης (Ε130), στο κτήριο του Τμήματος Μαθηματικών και Εφαρμοσμένων Μαθηματικών, του Πανεπιστημίου Κρήτης
Abstract
Gas sensors are devices capable of detecting the presence and concentration of various gases, playing a crucial role in applications such as air-quality monitoring, public safety, agriculture, and medical diagnosis. The most common sensing materials are metal oxide semiconductors, which have low-cost production and high sensitivity, albeit necessitate high temperatures or other external stimuli to operate. Therefore, there is need to develop new sensing materials that can overcome this limitation, while maintaining or offering better sensing performance. An alternative and promising candidate material for gas sensing is the group of all-inorganic metal halide perovskites, having the general formula ABX3, where A is an organic or inorganic cation, B is a metal cation, and X is a halide anion. They have exhibited the ability to detect gases (O3 and H2) at very low concentrations (a few ppb), featuring fast response times (few hundreds of seconds) without the demand of external triggering. However, challenges persist, including environmental instability and toxicity of lead, commonly utilized as the metal cation. Taking into account the aforementioned properties and needs, this project aimed to fabricate lead-free double halide perovskite gas sensing elements (Cs2AgBiBr6) in the form of nano- or micro-crystals, employing a straightforward and room-temperature ligand-free precipitation method. Furthermore, the perovskites were conjugated with 2D graphene-based materials and Transition Metal Dichalcogenides (TMDs) to enhance their conductivity and their sensing ability. Diverse synthesis methods and characterization techniques were used to optimize the fabrication process and understand the sensing mechanisms of those novel materials. Cs2AgBiBr6 nanocrystals found to be capable of detecting low O3 concentrations down to 50 ppb, having response and recovery times around 1 minute.
12 Ιουνίου 2024
Invitation to a Public Presentation of his Doctoral Thesis
Mr. Konstantinou Loukelis
Supervising Professor: Maria Chatzinikolaidou
(According to article 95, par. 3 of Law 4957/2022, Official Gazette 141 vol. A/21.7.2022)
On Wednesday, June 19, 2024 at 12:00 in the E-Learning room E130 of the Department of Mathematics and Applied Mathematics of the University of Crete, there will be a public presentation and support of the Doctoral Thesis of the PhD candidate of the Department of Materials Science and Engineering, Mr. Konstantinos Loukelis, on the subject :
«Fabrication of Electrospun and 3D Bioprinted Scaffolds for Bone Tissue Engineering Using Natural and Synthetic Biomaterials»
Abstract
Bone tissue engineering (BTE) is a broad research field that focuses on the use of biomaterial-based platforms combined with regeneration competent cell types and biochemical stimulants such as growth factors towards the fabrication of scaffolds and constructs that can restore, improve, or regenerate bone tissues. These biomaterial-based scaffolds should have a biocompatible character, controllable degradation rate, low immunogenicity, and mechanical attributes that are equivalent to those met in the native bone. State of the art biomaterials processing techniques such as electrospinning and 3D bioprinting have enabled the production of such scaffolds of varying 2D or 3D dimensionality, with topological and chemical structure that closely mimics that of bone tissue. The main objective of this thesis was the development of innovative bone regeneration promoting scaffolds and constructs based on the combination of two water soluble polymers, gellan gum (GG) and polyvinyl alcohol (PVA), via the state of the art technologies of electrospinning and 3D bioprinting. Through optimization of biomaterials composition, we produced stable GG:PVA nanofibrous scaffolds of various concentration ratios and verified that increased GG concentration and thermal treatment of scaffolds led to significantly reduced degradation rates, matching those of flat bones, while all compositions showed excellent osteogenic responses in the presence of pre-osteoblastic cells. We then biofabricated 3D bioprinted constructs, containing PVA:GG at different ratios, with and without the implementation of nano-hydroxyapatite (nHA), an osteogenic inorganic material present in human bone, and examined their biomechanical responses. It was corroborated that lower GG:PVA ratio compositions presented enhanced printability and cell viability than the stiffer counterparts, while the presence of nHA resulted in significantly enhanced printing fidelity and osteogenic capacity. Based on the optimization of the GG:PVA bioprinting conditions, we bioprinted constructs with human adipose derived stem cells (ADSCs), by incorporating zinc substituted mesoporous bioactive glasses (Zn-MBGs) in the same polymeric matrix, and observed excellent osteogenesis and chondrogenesis related cellular responses showcasing promising aspects for further use of these composite bioinks as potential personalized human osteochondral implants.
07 Ιουνίου 2024
Πρόσκληση σε Δημόσια Παρουσίαση της Διδακτορικής Διατριβής του
κ. Κωνσταντίνου Μαυράκη
Επιβλέπων: Ιωάννης Ζαχαράκης
(Σύμφωνα με το άρθρο 95, παρ. 3 του Ν. 4957/2022, ΦΕΚ 141 τ. Α΄/21.7.2022)
Την Τρίτη 11 Ιουνίου 2024 και ώρα 14:00
στην αίθουσα Τηλεεκπαίδευσης Ε130 του Τμήματος Μαθηματικών και Εφαρμοσμένων Μαθηματικών του Πανεπιστημίου Κρήτης, θα γίνει η δημόσια παρουσίαση και υποστήριξη της Διδακτορικής Διατριβής του υποψήφιου διδάκτορος του Τμήματος Επιστήμης και Μηχανικής Υλικών κ. Κωνσταντίνου Μαυράκη, με θέμα:
«Development of a Multiparametric Label-Free Imaging System for the Early Diagnosis of Neurodegenerative Disorders through the Ocular Cavity»
Περίληψη
“In this novel imaging system, we have combined three non-invasive and label-free imaging techniques: Optoacoustic microscopy (OAM) , non-linear microscopy (NLM) and Stimulated Raman Scattering (SRS) microscopy. OAM exhibits resolution comparable to that of optical microscopy, but can penetrate deeper into high-scattering tissue. The increased possibilities stem from the fundamental scattering difference between light and sound, which constitute the signal for optical microscopy and OAM, respectively. NLM includes two photon excitation fluorescence (TPEF) and Second Harmonic Generation (SHG). OAM, TPEF, SHG and SRS are combined complementary and thus reveal a wide range of discrete and non overlapping information. TPEF presents crisp contrast between bio-molecules that possess different excitation or emission spectra. SHG can provide information about biological structures such as lipid depositions while OAM pinpoints photon absorbing molecules with non-radiative relaxation. SRS imaging provides chemical information with high specificity allowing molecular pattern recognition inside tissues and their association with diseases and pathological conditions. Using these techniques, even sensitive and unreachable structures like the retina and the ocular cavity can be investigated with high resolution. The nerve fibers in the ocular cavity are essentially an extension of the central nervous system and since several neurodegenerative disorders present symptoms in the cavity, they could be diagnosed before the manifestation of conventional symptoms. The presence of possible bio-markers was investigated with TPEF, SHG and OAM in retina samples from mouse models of Alzheimer's disease."
06 Ιουνίου 2024
Πρόσκληση σε Δημόσια Παρουσίαση της Διδακτορικής Διατριβής του
κ. Ευάγγελου Ανδρέου
Επιβλέπων Καθηγητής: Γεράσιμος Αρματάς
(Σύμφωνα με το άρθρο 95, παρ. 3 του Ν. 4957/2022, ΦΕΚ 141 τ. Α΄/21.7.2022)
Την Πέμπτη 13 Ιουνίου 2024 και ώρα 10:00 στην αίθουσα Τηλεεκπαίδευσης Ε130 του Τμήματος Μαθηματικών και Εφαρμοσμένων Μαθηματικών του Πανεπιστημίου Κρήτης, θα γίνει η δημόσια παρουσίαση και υποστήριξη της Διδακτορικής Διατριβής του υποψήφιου διδάκτορος του Τμήματος Επιστήμης και Μηχανικής Υλικών κ. Ευάγγελου Ανδρέου, με θέμα:
«Porous Mesoscopic Assemblies of Spinel Chalcogenide and Transition Metal Phosphide Nanoparticles for Photocatalytic Energy Conversion Applications»
Περίληψη
The persistent rise in fossil fuel consumption, driven by the need to satisfy current energy demands, poses a significant environmental hazard, primarily due to the substantial emissions of hazardous gases into the atmosphere. While it is evident that renewable energy sources must replace a significant portion of fossil fuels, existing renewable energy production methods often lack efficiency and still present environmental challenges. Photocatalytic water splitting for hydrogen production stands out as a low-cost technique, offering a high solar to chemical conversion efficiency while emitting zero hazardous gases. Over the last few decades, the research community has explored various photocatalysts, including metal oxides, chalcogenides, nitrides, and more. Despite considerable progress in the development of photocatalytic materials, current synthetic methods often fail to provide precise control over electrochemical properties, morphology, and size of particles, leading to subpar photocatalytic performance.
In this dissertation, we introduce a new, cost-effective and environmentally friendly synthetic protocol for fabricating mesoporous networks of interconnected thiospinel (MIn2S4, M = Zn, Cd) nanocrystals, serving as versatile building blocks. This synthetic approach provides the advantage of adjusting the size of the constituent inorganic nanocrystals, offering significant benefits for photocatalytic energy conversion applications. Such a controllable synthesis enables precise engineering of the optical and electronic properties of the resulting photocatalysts. Namely, employing a straightforward polymer-templated self-assembly process, the thiospinel nanocrystals are organized into three-dimensional (3D) mesoporous networks with large internal surface area and we-defined pores. This structural arrangement leads to improved charge transfer kinetics and better intraparticle diffusion of the electrolyte. Given their advantageous characteristics, the mesoporous ensembles were investigated as potential photocatalysts for the water splitting reaction towards hydrogen evolution. Furthermore, by carefully selecting suitable co-catalysts such as Ni2P, Co2P, and β-Ni(OH)2, we uncovered their significant impact on the photochemical properties of the resulting composite structures. Utilizing a combination of spectroscopic and (photo)electrochemical techniques, we identified that the formation of the thiospinel/metal phosphide/hydroxide nano-heterojunctions significantly enhances the separation and transfer ability of the photogenerated charge carriers, leading to high photocatalytic stability and activities. Notably, these improvements exceed those reported for previously studied high-performance multicomponent thiospinel-based photocatalytic systems. Overall, this research presents a novel synthetic perspective for the rational design of photocatalysts and advances our understanding of next generation photocatalysts for clean energy conversion applications. By shedding light on key aspects of inorganic synthetic chemistry, interface engineering and photochemical reactions, the findings of this work make a significant contribution to the broader research endeavor focused on the development of sustainable energy technologies.
30 Μαΐου 2024
Πρόσκληση σε Δημόσια Παρουσίαση της Διδακτορικής Διατριβής του
κ. Μιχαήλ Μυλωνάκη
Επιβλέπων: Ιωάννης Ζαχαράκης
(Σύμφωνα με το άρθρο 95, παρ. 3 του Ν. 4957/2022, ΦΕΚ 141 τ. Α΄/21.7.2022)
Την Πέμπτη 6 Ιουνίου 2024 και ώρα 10:00 στην αίθουσα Τηλεεκπαίδευσης Ε130 του Τμήματος Μαθηματικών και Εφαρμοσμένων Μαθηματικών του Πανεπιστημίου Κρήτης, θα γίνει η δημόσια παρουσίαση και υποστήριξη της Διδακτορικής Διατριβής του υποψήφιου διδάκτορος του Τμήματος Επιστήμης και Μηχανικής Υλικών κ. Μιχαήλ Μυλωνάκη, με θέμα:
«Wavefront Shaping for Microscopic Imaging of Biological Samples»
Περίληψη
“Imaging of biological samples is one of the driving application fields of optical microscopy. Although several other imaging techniques have been developed the simplicity, the effectiveness and the non-invasive nature of optical microscopy are the key factors of its widespread use in Biology.
An important limiting factor for optical microscopy is the scattering of light as it propagates through biological tissue. The inherent random variations of the optical properties, lead to a diffusion dominated propagation that drastically limits the effective imaging range down to 1 mm. On the other hand, recent advances in the spatial modulation of the light beam that illuminates the sample combined with analysis of the detected light distribution have opened the way to beat the diffusion limit.
Τhis PhD thesis was focused on leveraging the concept of the 'opaque lens' by utilizing engineered disorder in photonic structures. This involved developing novel scattering media and their integration with wavefront shaping into imaging modalities. Using this approach, we have reached to the development of a fully functional fluorescence microscope that, in several aspects, outperforms current instrumentation capable of performing in vivo fluorescence microscopy."
19 Μαΐου 2024
The School of Medicine, the Department of Computer Science, the Department of Materials Science and Engineering of the University of Crete (UoC), the School of Electrical and Computer Engineering of the Technical University of Crete (TUC), and the Foundation for Research and Technology - Hellas (FORTH) announce that applications for the academic year 2024-2025 for the Joint Master's Program in "Biomedical Engineering" are now open!
The objective of the joint MSc Program in Biomedical Engineering is to provide advanced education, required qualifications and skills to its graduates to meet the ever-increasing demand for high-level specialization in the field of biomedical engineering. Graduates of our joint MSc program in BME may be employed in hospitals, medical equipment / instrumentation industry, pharmaceutical industry, government agencies or follow academic careers towards pursuing a PhD degree. The official instruction language of the program is English.
The deadline for submitting the application and supporting documents is May 26, 2024.
For more information about the program and the application procedure, please visit the site.