Call for Applications for Postgraduate Studies in the Department of Materials Science and Technology of the University of Crete

25 Ιουλίου 2024

The Department of Materials Science and Technology of the University of Crete announces a limited number of postgraduate student positions for the academic year 2024-2025. The offered educational and research activities of the program are:

• Optoelectronics - Magnetic materials - Nanotechnology,
• Polymers - Colloids,
• Theoretical - Computational Materials Science,
• Synthetic Chemistry of Materials,
• Biomaterials - Biomolecules.

Deadline for submission of the application and supporting documents for the Postgraduate Program is set for September 2nd, 2024. The interviews will take place on September 9th, 2024 between 9:00 - 13:00.

More Information

Παρουσίαση Μεταπτυχιακής Διπλωματικής Εργασίας της κ. Νικάνδρας Παπακώστα

19 Ιουλίου 2024

ΠΑΝΕΠΙΣΤΗΜΙΟ ΚΡΗΤΗΣ

ΤΜΗΜΑ ΕΠΙΣΤΗΜΗΣ ΚΑΙ ΜΗΧΑΝΙΚΗΣ ΥΛΙΚΩΝ

 ΠΑΡΟΥΣΙΑΣΗ ΜΕΤΑΠΤΥΧΙΑΚΗΣ ΔΙΠΛΩΜΑΤΙΚΗΣ ΕΡΓΑΣΙΑΣ

 

Τίτλος

«Laser Induced Periodic Surface Structures on Metallic and Semiconductor Surfaces for Hydrogen Production through Alkaline Electrolysis»  

της Νικάνδρας Παπακώστα

μεταπτυχιακής φοιτήτριας του Τμήματος Επιστήμης και Μηχανικής Υλικών του Πανεπιστημίου Κρήτης

 Επιβλέπων: Παναγιώτης Λουκάκος

 

Παρασκευή 26 Ιουλίου 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

The present thesis examines the enhancement of hydrogen production through the fabrication of nanostructured electrodes and their application in alkaline electrolysis. The primary focus is on the Hydrogen Evolution Reaction (HER) and the impact of nanostructured surfaces on improving reaction efficiency.

Νanostructured nickel electrodes were fabricated using ultrashort laser pulses to form periodic surface structures. Additionally, measurements were conducted on nickel electrodes subjected to electrodeposition (ELN) and on iron electrodes. ELN two-step fabrication process was employed to effectively enlarge the electrocatalytic area of the electrodes in an alkaline electrolysis setup. Initially, ultrashort laser pulses were used to nanostructure the electrode surfaces, followed by the electrodeposition of nickel particles. Furthermore, nickel foam (NF) electrodes with increased surface area were explored through the deposition of nickel using the Pulsed Laser Deposition (PLD) technique. High-resolution Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were employed for structural and morphological characterization of the prepared electrodes.

The efficiency of hydrogen production was assessed using a custom-made electrolysis cell. For laser-nanostructured nickel electrodes, the hydrogen production efficiency increased by a factor of 3.7. In contrast, electrodeposited-laser-nanostructured nickel electrodes (ELN) showed an enhancement factor of 4.5, and laser-nanostructured iron electrodes exhibited a factor of 2. These enhancements were corroborated by current-time measurements during electrolysis.

Nickel foam electrodes decorated with nickel nanoparticles at various deposited thicknesses (using PLD) were also investigated for their HER performance. The electrodes exhibited significantly increased HER activity, attributed to the enlarged electrochemically active surface from the laser-induced periodic surface nanostructures. The structural and morphological characteristics were analyzed using FE-SEM, XRD, and XPS. The optimal deposition thickness was determined to be 300 nm. The NF electrode decorated with 300 nm Ni nanoparticles (Ni/NF 300) demonstrated superior electrochemical characteristics, with a 15-fold increase in electrochemically active surface area (ECSA) compared to the bare NF electrode.

This study provides a comprehensive analysis of the significant improvements in hydrogen production efficiency achieved through the innovative fabrication of nanostructured electrodes, highlighting the potential for advancing material processing technologies in the green energy sector.

Παρουσίαση Μεταπτυχιακής Διπλωματικής Εργασίας της κ. Σουλτάνας Νικολέττας Πίκου

17 Ιουλίου 2024

ΠΑΝΕΠΙΣΤΗΜΙΟ ΚΡΗΤΗΣ

ΤΜΗΜΑ ΕΠΙΣΤΗΜΗΣ ΚΑΙ ΜΗΧΑΝΙΚΗΣ ΥΛΙΚΩΝ

 

ΠΑΡΟΥΣΙΑΣΗ ΜΕΤΑΠΤΥΧΙΑΚΗΣ ΔΙΠΛΩΜΑΤΙΚΗΣ ΕΡΓΑΣΙΑΣ

 Τίτλος

«Optical Characterization of Perovskite Single Crystals»

της Σουλτάνας - Νικολέττας Πίκου

μεταπτυχιακής φοιτήτριας του Τμήματος Επιστήμης και Μηχανικής Υλικών του Πανεπιστημίου Κρήτης

 Επιβλέπων Καθηγητής: Νικόλαος Πελεκάνος

 Παρασκευή 19 Ιουλίου 2024 Ώρα 15:00

H παρουσίαση θα πραγματοποιηθεί στην αίθουσα Τηλε-εκπαίδευσης (Ε130), στο κτήριο του Τμήματος Μαθηματικών και Εφαρμοσμένων Μαθηματικών, του Πανεπιστημίου Κρήτης

Abstract In this master thesis the optical properties of Methylammonium Lead Trichloride Single Crystals (MAPbCl3 SCs) of high-optical quality were investigated. The characterizations techniques used were Photoluminescence, Reflectivity and Time resolved Photoluminescence at different powers and temperatures, giving thus a detailed characterization of the crystals. By combining and analyzing the collected data we have reached several conclusions: the main emission peak is Stokes-shifted with respect to the free-exciton line by about 15-20 meV and is due to emission of localized excitons in shallow traps. With increasing temperature, the main emission peak loses intensity by ionization of the localized excitons directly to the electron-hole continuum of states. We show that additional secondary-emission peaks are either part of a cascade trapping process initiated at the localized exciton states of the main emission peak or represent emission at “cubic” inclusions inside the predominantly orthorhombic lattice at low temperatures. Finally, the MAPbCl3 SCs were mechanically polished and the resulting spectra are compared to the pristine ones, while several differentiations were observed.

Πρόσκληση Τελετής Ορκωμοσίας Τμήματος Επιστήμης και Μηχανικής Υλικών

15 Ιουλίου 2024

Η Πρόεδρος του Τμήματος Επιστήμης και Μηχανικής Υλικών Καθηγήτρια κ. Μαρία Βαμβακάκη σας προσκαλεί στην τελετή αποφοίτησης την

Τετάρτη, 24 Ιουλίου 2024 και ώρα 11:00

στο αμφιθέατρο «Πετρίδης», Κτήριο Τμήματος Μαθηματικών και Εφαρμοσμένων Μαθηματικών

Δείτε την Πρόσκληση Τελετής Αποφοίτησης.

Παρουσίαση της Διδακτορικής Διατριβής της κ. Γεωργίας- Ιωάννας Κοντογιάννη

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.

Παρουσίαση Μεταπτυχιακής Διπλωματικής Εργασίας του κ. Αλέξανδρου Παπαδάκη

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.

Παρουσίαση Μεταπτυχιακής Διπλωματικής Εργασίας του κ. Εμμανουήλ Μαθιουδάκη

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.

Παρουσίαση Μεταπτυχιακής Διπλωματικής Εργασίας της κ. Κωνσταντίνας Λυρώνη

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.

Παρουσίαση Μεταπτυχιακής Διπλωματικής Εργασίας της κ. Μαρίας Συσκάκη

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.

Παρουσίαση της Διδακτορικής Διατριβής του κ. Κωνσταντίνου Λουκέλη

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.