Evangelia A. Pavlatou

N. Grammenos, P. Tsanakas, E.A. Pavlatou

Education and Development Conference (INTED 2017) (2017), Valencia (Spain), March 6- 8 (oral)

This study concerns an innovative platform entitled “AESOP: Advanced Electronic Scenarios Operating Platform” which was developed to enable teachers and pupils to design, develop and evaluate interactive educational material. Special emphasis is placed on the presentation of the features and the potential of this electronic system as an integrated learning teaching and research tool of electronic lessons that exploits modern web technologies without any software add-ons, using only a modern Web Browser at any desktop or mobile computing device. The structure of the educational/teaching scenario is designed and extracted dynamically from the platform. There is extensive reference to the use and exploitation of a considerable number of free web-based tools for the design of an original or the reuse of an existing digital material, as well as, to the possibility of transforming a digital material into an interactive application. In each scenario the creator/designer, by using knowledge, experience and imagination, is able to create a compound digital material in accordance with one or more cognitive subjects, thematic areas and classifications. This is done by describing teaching goals and objectives, instructional phases and worksheets, and fully adjust them into the structure of a modern and pedagogically exploitable digital educational/teaching scenario that is consistent with the current applied Greek curricula of education. The potential of the AESOP Platform has already been exploited by thousands of Greek teachers. Currently the platform hosts high quality teaching digital material, scientifically and pedagogically accredited by the responsible scientific authority for educational issues of the primary and secondary education in Greece (Greek Institute of Educational Policy). Any teacher in Greece, has the potential to choose among 39 cognitive subjects of the primary and secondary education and to design digital interactive educational/teaching scenarios for all students, for diverse groups of students or even for individual students with special needs or inclinations.

K. Dalacosta, G. Korakakis, E.A. Pavlatou

Proceedings of ICERI2012 Conference (2012), Madrid, Spain, 19-21 November (poster)

In comparison with the traditional books, e-books can provide students of elementary and secondary education with increased resources, and in turn promote their learning effectiveness and outcome. In this work, in order to make the use of e-books more appealing to students from different ages; we have enriched them with multimedia educational games. A series of multimedia educational games were manufactured addressed at students of different ages that served specific educational goals; in this paper three indicative ones will be presented. Specifically, for the elementary education (5th grade) we have built an educational game called “RECYCLING KEEP OUR FORESTS CLEAN”. For the secondary education (9th grade) we have constructed the games entitled “THE HOUSE OF SILICON” and “THE ROOM OF CARBON”. There were designed as fun activities through which students can involve, learn, understand and in some cases even practice the knowledge that they have obtained, which is a crucial step in the education. Future detailed work will be conducted in order to demonstrate that multimedia educational games on e - books can be used by the teacher as an effective supplementary didactical tool for teaching science.

P. Gyftou, S. Spanou, A. Gialamopoulou, E.A. Pavlatou

9th European Symposium on Electrochemical Engineering (9th ESEE) (2011), Chania-Greece, June 20-24, (CD-rom) (oral)

Nickel electrodeposits were produced from a Watts type bath with the addition of cis 2-butene-1,4-diol and application of pulse current conditions. The surface morphology, the preferred orientation and grain size of Ni coatings were determined as a function of the concentration of the additive in bath and the frequency of imposed current pulses. The microhardness of the coatings was also assessed from the viewpoint of crystal orientation, grain size, presence and concentration of additive and type of imposed current. The results indicate that the effect of the additive on the properties of the coatings is accelerated in the case of pulse plating mode. The combined imposition of predefined pulse current conditions and additive concentration in the bath leads to specific textural modifications accompanied by considerable nano-sized grain refinement of the coatings. The overall experimental data indicate that the production of hard and bright nanostructured deposits could be obtained under pulse current regime and reduced amounts of cis 2-butene-1,4-diol compared to direct plating.

I. Tzigounakis N. Kalogeropoulos, A. Boudouvis, E.A. Pavlatou

International Conference of Education, Research and Innovation (ICERI 2009) (2009), Madrid (Spain), November 16-18, p. 6990-6997 (CD-rom) (poster)

Emerging technologies such as Internet-based e-learning and course management systems currently being developed using web technologies, provide academic teachers with a wide variety of tools in order to support the traditional educational process. Unfortunately, many teaching staff lack the technical knowledge needed to use complex e-learning tools meant to support their conventional teaching methods. With the purpose of overcoming such difficulties, a modular user-friendly web-based course management tool has been developed utilizing simple to use technologies. This study will be looking into the course management tool developed and used at the National Technical University of Athens’ Chemical Engineering School. Initially, the designing principles of the software are presented followed by its architecture, which is based on a modular client-server topology. The specific modules used by the software, incorporate a number of tools and technologies which aim to simplify the organizing of the elements involved in the process of developing an easier to manage educational website. In this presentation, our aim is to analyze the content and the specific features of the tool, as well as to address a few of the challenges that have emerged while working with it so far, focusing especially on its usability and user-friendliness.

N. Kalogeropoulos, E.A. Pavlatou, A. Boudouvis, I. Tzigounakis

International Conference of Education, Research and Innovation (ICERI 2009) (2009), Madrid (Spain), November 16-18, p. 6990-6997 (CD-rom) (poster)

In recent years, computer-based assessment (CBA) has been developed significantly and is increasingly implemented for student evaluation all over the world. In this study the score equivalence of CBA and PPT in an undergraduate course of introductory computer programming at the National Technical University of Athens' School of Chemical Engineering is examined. In order to test the efficiency of CBA, 211 students participated in a properly designed practical examination, which utilized a specially constructed CBA platform along with the classical PPT and which consisted of multiple-choice type questions, completing and correcting code in MatLab and Fortran, as well as writing code in Fortran. Our results showed in general that students performed better and got higher scores under CBA compared to PPT. However, different results were recorded for each part of the test. For the first part, namely the multiple choice questions, students got comparable scores both in CBA and PPT. For the second and third part, i.e. the exercises in Fortran and MatLab, a significant difference between the students' performance in the two versions of the test was revealed. Overall, the findings of this study revealed that the actual programming abilities of the students are better evaluated using such CBA tests in programming courses.

K. Dalacosta, E.A. Pavlatou, M. Kamariotaki-Paparrigopoulou, J. Palyvos

International Technology Education and Development Conference (INTED 2009) (2009), Valencia (Spain), March 9 – 11,  p. 3497-3504 (CD-rom) (poster)

This study reports research findings on the use of animated cartoons in a multimedia application that meant to evaluate their effectiveness in supporting teaching and learning in chemistry. The research was carried out with 184 students of 5th grade in Greece. The animated cartoons in the multimedia application were designed from scratch using appropriate programs. The application that was created consists of two major parts. In the first part (the introduction story), the presentation and the analytic explanation of solubility and factors that influence it, was attempted via animated cartoons and hearing dialogues, thus aiming at both the comprehension and the assimilation of the above concepts. In the second part of the application (the questionnaire), a series of closed-type questions were presented. Two different instructional methods were used i.e. the classic instruction and the animated cartoons multimedia application. The present study reveals how students at the age of eleven can better understand specific scientific concepts which are difficult to comprehend and often can cause misconceptions to them, with the help of animated cartoons. Moreover, the principal findings of this study show that students' knowledge and understanding was upgraded through the differentiation of the concepts of dissolving, melting and disappearing in the solution chemistry with the use of animated cartoons.

G. Korakakis, E.A. Pavlatou, J. Palyvos, N.Spyrellis

International Conference of Education, Research and Innovation (ICERI 2008) (2008), Madrid (Spain), November 17-19, (CD-rom) (poster)

The aim of this research was to determine whether the use of specific types of visualization (3D illustration, 3D animation and interactive 3D animation) combined with narration and text contributes to the learning process of 17 and 18 years-old students in science courses.The study was carried out in Greece in a sample of 114 students of 12th grade. This exploratory study utilized three different versions of an interactive multimedia application called "Atomic Orbitals", each one differing from the other two in the type of visuals. All the rest of the application components (narration, text, navigation, auxiliary tools, interface, etc.) were common in all three versions. This multimedia application was produced from scratch, based on the latest educationally acceptable theories and researches in various multimedia visualizations. In the last part of the multimedia application, the students were asked to answer questions of various types. The percentage of correct answers was recorded and presented at the end of the application. The questions in all three versions were precisely the same and were presented in the same way. The research results indicated that interactive 3D animations have a greater contribution to the learning process than the other two types of visualization. The findings also suggested that all three types of the multimedia application increase the interest of students and make the material more appealing to them. Furthermore, they suggested that there is an obvious correlation between the total time that the students dedicated to the scenes and the percentage of correct answers, in the application versions with interactive 3D animations, as well as with (non-interactive) 3D animations.

P. Papavasilopoulou, A. Zoikis – Karathanasis, E.A. Pavlatou, N. Spyrellis

Proceedings of the 7th International Conference “THE Coatings” (2008), October 1-3 2008, Kallithea Chalkidiki, Greece Ziti Editions (Eds. K.D. Bouzakis, Fr.W. Bach, B. Denkena, M. Geiger), p. 417-425 (oral)

NiP-SiC composite coatings were produced under both direct and pulse current conditions from an additive-free modified Watts type bath. The influence of current parameters and hydrodynamic conditions of plating bath in the structure, morphology and mechanical properties of the composite coatings were examined. Additionally, micro-structural and hardness modifications induced by specific heat treatment of the coatings were investigated. Structural analysis revealed the production of an amorphous NiP matrix for the majority of the coatings. However, the phase Ni₁₂P₅ was detected for the first time in the NiP matrix for the deposits containing phosporous up to 12wt.%, prepared under specified experimental conditions. Furthermore, the percentage of the embedded SiC microparticles was found to be strongly dependent on the duty cycle of the imposed pulses.

S. Spanou, E.A. Pavlatou, N. Spyrellis

Proceedings of 7th International Conference “THE Coatings” (2008), October 1-3 2008, Kallithea Chalkidiki, Greece, Ziti Editions (Eds. K.D. Bouzakis, Fr.W. Bach, B. Denkena, M. Geiger), p. 399-408 (oral)

Nanocomposite coatings were obtained by electrochemical codeposition of TiO₂ nanoparticles (21 nm) with nickel from an additive-free Watts type bath by applying direct and pulse current conditions. The surface morphology, the crystallographic orientation of nickel matrix, the grain size and the microhardness of the deposits were investigated, along with the distribution and the percentage of the embedded nanoparticles in the nickel matrix, affected by the electrodeposition parameters (pH, current density) and the concentration of TiO₂ nanoparticles in the bath. The effect of codeposition percentage of TiO₂ nanoparticles and type of imposed current were investigated regarding the microhardness and microstructure of the electrodeposits. Ni/TiO₂ composite deposits prepared under either direct or pulse current conditions exhibited a considerable strengthening effect with respect to pure Ni coatings. Moreover, it has been revealed that the microhardness of the composite coatings is associated to the induced crystalline nickel orientation and the nickel grain size.

I. Masavetas, A. Moutsatsou, E. Nikolaou, S. Spanou, A. Zoikis – Karathanasis, E.A. Pavlatou, N. Spyrellis

Proceedings of the WasteEng08-2nd International Conference on Engineering for Waste Valorisation (2008), Patras, Greece, June 3-5, (CD-rom) (oral)

Waste electrical and electronic equipment (WEEE) is becoming a general trend of today, as it is one of the fastest growing waste streams in the world. In the present study PCBs were treated thermally and dissolved in three different acid media in order to dissolute copper. Electrodeposition technique was applied aiming to recover dendritic structure of copper. More than 98% of copper was recovered accompanied by a high current efficiency. The applied process led to a copper powder of 80 μm mean diameter.

N. Spyrellis, E.A. Pavlatou, S. Spanou, A. Zoikis – Karathanasis

Proceedings of the NPS 08 Nanoscale Phenomena and Structures in Bulk and Surface Phases (2008), 26/02-02/03/2008, Prof. Marin Drinov Academic Publishing House (Ed. by D. Kashchiev), Sofia, p. 221-228 (oral)

Composite coatings were obtained by electrochemical co-deposition (i) of TiO₂ nanoparticles (mean diameter 21 nm) with nickel, from an additive-free Watts type bath by applying direct current (DC) and (ii) NiP composite coatings with tungsten carbide (WC) nanoparticles (mean diameter 200 nm) from a modified organic-free Watts bath under direct, as well as pulse, current conditions. For comparison, pure Ni and NiP deposits were also produced under the same experimental conditions. The influence of the variable electrolysis parameters (type of current, frequency, pH and current density) and the reinforcing particles properties (type, size, shape, concentration and dispersion in the bath) on the surface morphology, the structure and properties of the deposits will be demonstrated. In the case of Ni/TiO₂ composite coatings the observed textural modifications of composite coatings are associated with specific structural modifications of Ni crystallites provoked by the absorption-desorption phenomena occuring on the metal surface, induced by the presence of TiO₂ nanoparticles. Regarding the NiP-WC composite coatings, the experimental findings proved that the imposition of pulse current conditions leads to more compact coatings with increased embedded particles, more homogenous distribution of the nanoparticle and increased micro-hardness, compared to those produced under direct current conditions.

A. Zoikis - Karathanasis, E.A. Pavlatou, N. Spyrellis

Proceedings of the 6th International Conference “THE Coatings''  (2007), Hannover, Germany, October 25-27, p.257-265 (oral)

 In the present work nickel-phosphorous (NiP) and NiP composite coatings with tungsten carbide (WC) nanoparticles (mean diameter 200 nm) as a reinforcing mean have been produced from a modified, organic free, Watts bath, under direct, as well as pulse current conditions. The effect of the electrolysis parameters, like type of current and frequency of imposed pulses on the structure, the morphology, the mechanical properties and the mechanism of WC particles embedment was studied. Furthermore, the impact of heat treatment at 400°C on the above mentioned properties was investigated. The composite coatings that have been produced were compact and the pulse plating conditions led to deposits with higher percentage of embedded nanoparticles, better distribution of nanoparticles in the matrix and enhanced mechanical properties than those prepared under direct plating conditions. Moreover the coatings demonstrated significantly high micro-hardness values, especially after specific thermal treatment.

E.A. Pavlatou, P. Assimidis, N. Spyrellis

Proceedings of the Euro-Interfinish 2007 - Nanotechnology and Innovative Coatings (2007), Athens, October 18-19, (CD-rom) (oral)

The electrochemical deposition of finely dispersed particles in a metallic matrix has led to a new generation of composites, a process that provides the possibility to produce composite coatings with different combination of properties, such as improved wear and corrosion resistance relative to the metal matrix, by changing properly the electroplating parameters. In this study Ni matrix composite electrocoatings containing WC particles with a mean size of 100 and 200 nm were produced by an additive-free Watts type bath. Electrodeposition of Ni/WC composites was carried out on a rotating disk electrode under both direct and pulse current conditions, in order to study the effect of the electroplating parameters, such as type of current, rotation velocity of the cathode and duty cycle of the imposed pulse on the tribological properties of Ni/WC composite coatings. The crystallographic orientation of nickel matrix, the distribution and the percentage of the embedded particles were examined, as well as the structure and the surface morphology of the produced composite coatings. In order to study the tribological behaviour of the composites, ball-on-disc wear tests were performed and the coefficient of friction, as well as the volumetric wear factor of the composite coatings were estimated. The tribological properties of the composite Ni/WC electrocoatings were shown to depend on the type of current, the codeposition percentage of particles and the microstructural modification induced by codepositing WC particles. Specifically, the best wear resistance is observed for composite coatings prepared at low duty cycles and high rotation velocity of cathode, containing reduced size of embedded WC particles. Furthermore, it has been revealed that in comparison with pure nickel, the incorporation of WC particles in Ni matrix improves significantly the wear behaviour of composite coatings. 

A. Zoikis - Karathanasis, E.A. Pavlatou, N. Spyrellis

Proceedings of the Euro-Interfinish 2007 - Nanotechnology and Innovative Coatings (2007), Athens, October 18-19, (CD-rom) (oral)

In the present work pure nickel–phosphorous and nickel–phosphorous composite coatings with WC particles (mean diameter 200 nm) have been produced under both direct and pulse current conditions, from a modified, organic-free, Watts bath. The produced coatings were thermally treated at various temperatures and the structure, morphology and the microhardness of the deposits were examined after each cycle of heat treatment. Imposition of pulse current conditions led to composite deposits with high-incorporation percentage of WC particles in the matrix. Also, the presence of WC particles resulted in coatings with enhanced microhardness values and retarded diffusion phenomena in the deposits during thermal treatment. Annealing of all coatings at 400°C revealed complete crystallization of the matrix to the phases of Ni, Ni₂P and Ni₃P accompanied by a significant increase of microhardness for all deposits. Further heating at higher temperatures demonstrated a decrease in microhardness of both kinds of deposits. The experimental data proved that it is possible to produce NiP–WC composite coatings under specific pulse current conditions followed by proper thermal treatment that exhibited considerable enhanced microhardness.

S. Spanou, E.A. Pavlatou, N. Spyrellis

Proceedings of the Euro-Interfinish 2007 - Nanotechnology and Innovative Coatings (2007), Athens, October 18-19, (CD-rom) (oral)

Nanocomposite coatings were obtained by electrochemical codeposition of TiO₂ nanoparticles (mean diameter 21nm) with nickel from an additive-free Watts type bath. The electrodeposition of Ni/TiO₂ composites was carried out on a rotating disk electrode (RDE), by applying direct current (DC). Pure Ni deposits were also produced under the same experimental conditions for comparison. The surface morphology, the crystallographic orientation of nickel matrix and the grain size of the deposits were investigated along with the distribution and the percentage of the embedded nanoparticles in nickel matrix, as a function of pH, current density and concentration of TiO₂ nanoparticles in the bath. The observed textural modifications of composite coatings are associated with specific structural modifications of Ni crystallites provoked by the absorption-desorption phenomena occuring on the metal surface, induced by the presence of TiO₂ nanoparticles. It has been observed that the presence of TiO₂ nanoparticles favors the [100] texture of nickel matrix. Additionally, the influence of the electrolysis parameters, such as pH and current density, on the concentration of the embedded particles in the metal matrix has been established. The concentration of the codeposited particles affects the size of metal crystallites and consequently, the mechanical properties of the deposits. Moreover, the experimental findings demonstrate that the incorporation of the nanoparticles takes place, intercrystalline, as well as intracrystalline.

E.A. Pavlatou, N. Spyrellis

Proceedings of the 5th International Conference “The Coatings in Manufacturing Engineering” (2005), October 5-7, Chalkidiki, Ziti Editions (Eds. K.D. Bouzakis, B. Denkena, M. Geiger, H.K. Toenshoff), p. 425-433 (oral)

Ni matrix composite electrocoatings containing SiC particles were produced from an additive-free nickel Watts type bath. Electrodeposition of Ni/SiC composites was carried out under both direct and pulse current conditions, in order to study the effect of the electroplating parameters on the hardness and wear resistance of Ni/SiC composite coatings. The mechanical properties of the composite Ni/SiC electrocoatings were shown to depend on the electrolysis parameters, the type of current, the codeposition percentage of particles and the microstructural modification induced by codepositing SiC particles. The experimental data revealed that in comparison with pure nickel, the incorporation of SiC particles in Ni matrix improves significantly the mechanical behaviour of composite coatings.   

S. Psarrou, P. Gyftou, E.A. Pavlatou, C. Kollia, N. Spyrellis

Proceedings of the 15th World Congress on Surface Technology (2000), Garmisch-Partenkirchen, Germany, September 13-15, (CD-rom) (oral)

E.M. Anghel, C. Bessada, S. Zuca, E.A. Pavlatou

Progress in Molten Salt Chemistry 1 (2000), Special Volume in honor of Prof. Niels J. Bjerrumm, August 20-25, 2000, edited by Elsevier, p.59-62 (poster)

Raman, NMR and UV-Vis spectroscopy have been used to characterize the structural evolution of the Na₂B₄O₇-Na₃AlF₆ and Na₃AlF₆-TiO₂ binary subsystems of the quaternary system: NaCl-Na₂B₄O₇-Na₃AlF₆-TiO₂.

P. Gyftou, E.A. Pavlatou, N. Spyrellis

Proceedings of American Electroplaters and Surface Finishers Society, AESF SUR/FIN Technical Conference 2000 – EAST (2000), Chicago, USA, June 26-29, (484-488) (oral)

Several spare parts of the equipment in textile industry should exhibit some special characteristics due to their continue contact with very sensible materials, such as yarns, filaments, clothes. These parts must be very smooth, hard and possess very good wear resistance. In practice, manufacturers use very often hard chromium coated parts, which become useless in short periods of time due to their heavy duty performance and, consequently, must be substituted frequently. In this work, we have tried to substitute the hard chromium coatings by nickel matrix composite coatings, in order to ameliorate the surface aspect and the tribological properties. We have used nickel matrix coatings containing silicon carbide (SiC) micro-particles, prepared under pulse plating conditions. It has been proved that this technique, under very well defined conditions (pulsed current density, frequency, duty cycle, etc), permits us to obtain hard and smooth coatings, even in the absence of organic additives, which show improved tribological properties. As a result of this work, we have substituted certain chromium coated equipment components of the textile industry by these composite coated ones.

E.M. Anghel, E.A. Pavlatou, M. Balasoiu, S. Zuca

Proceedings of the International Conference Advances in Molten Salts (1999), Begel House Inc., NY-Wallingford, p. 23-31 (poster)

As part of the ternary system Na₃AlF₆-Na₂B₄O₇-TiO₂ the binary system Na₂B₄O₇-TiO₂ and the pseudobinary subsystem Na₂B₄O₇-[Na₃AlF₆-TiO₂]_e were investigated. The phase diagrams established by DTA measurements evidenced a simple eutectic point for both systems except for the concentration range >85wt.% Na₂B₄O₇ of the Na₂B₄O₇-[Na₃AlF₆-TiO₂]_e system where the binary paragenesis rules are no longer obeyed. Additional information regarding the structure of the mixtures were obtained by X-ray diffraction and Raman spectroscopy. Both vitreous and crystalline state were evidenced, without any new compound formation. The presence of titanium, mainly as TiO₄ tetrahedra, was also proved.