Maria Kalyva

• Researcher at Norwegian Institute of Public Health

Structural transitions in materials are accompanied by appreciable and exploitable changes in physical-chemical properties. Whereas reversible optically-driven atomistic changes in crystal-to-amorphous transitions are generally known and exploited in applications, the nature of the corresponding polyamorphic transitions between two structurally dis...

X-ray photoelectron spectroscopy and depth profile analysis were used to investigate the X-ray-induced silver photodiffusion into an amorphous As50Se50 thin film. At the initial stages of irradiation an induction period was observed while core level spectra analysis revealed the existence of a mixed As–Se–Ag interlayer between the metal and the cha...

In the present paper, x-ray photoelectron spectroscopy (XPS) is used to induce and study the Ag diffusion and dissolution in pulsed laser deposited As ₅₀ Se ₅₀ amorphous chalcogenide films. Dynamic secondary ion mass spectroscopy (SIMS) is also employed to investigate the Ag atomic concentration in depth. Dynamic SIMS measurem...

The effect of oxidation on the structural integrity of multiwalled carbon nanotubes through acidic (nitric acid and a mixture of sulfuric acid and hydrogen peroxide) and basic (ammonium hydroxide/hydrogen peroxide) agents has been studied. In order to purify the as-received material, a non-oxidative treatment (with hydrochloric acid) was also appli...

Single-walled carbon nanotubes were functionalized along their sidewalls with hydroxyalkyl groups using a radical addition scheme. These moieties were found to be active in the polymerization of acrylic acid from the surface of the nanotubes by a redox radical mechanism. The resulting polymerized nanotubes were analyzed by UV–Vis, XPS, Raman and SE...

The response of amorphous As50Se50 pulsed laser deposited (PLD) films to annealing and irradiation, was investigated by X-ray and UV-photoelectron spectroscopies. It is shown that annealing smoothes out structural as well as electronic defects, while irradiation with near band-gap light enhances the film's “chemical disorder” and causes the creatio...

Amorphous chalcogenide films from the binary system AsxSe100−x (x: 0,40,50,60,70,100) were prepared by pulsed laser deposition on Si substrates. Annealing-induced changes at the electronic environment of the constituent structural units of the films were investigated using X-ray photoelectron spectroscopy. The analysis has revealed three distinct l...

Annealing-induced structural changes in amorphous films AsxSe100−x (x: 0, 50, 100) prepared by pulsed laser deposition (PLD) on Si substrates were studied by x-ray and ultraviolet photoelectron spectroscopies (XPS, UPS). For x = 50, the analysis of the XPS As 3d peak revealed three distinct local environments in which the As atoms participate in th...

Ένα άρθρο που αναφέρεται στις αρχαίες κλεψύδρες, αλλά επικεντρώνει κυρίως στην Κλεψύδρα των Αθηνών που βρέθηκε στην Αρχαία Αγορά και φυλάσσεται σήμερα στο Μουσείο της Ρωμαϊκής Αγοράς των Αθηνών. Abstract An article which refers ito the ancient clepsydrae, and especially focuses on the Clepsydra of Athens found at the Ancient Agora and kept, today,...

Throughout the 17th century, a century that witnessed a revolution in Natural Sciences and the introduction of technology, new concepts contributed to the development of a new natural philosophy. The Universe was then thought to be a well-winded up clock, a concept that respectively fed the growth of a technology, able to manufacture mechanical clo...

Some ancient Greek philosophers and thinkers questioned the geocentric system and proposed instead a heliocentric system. The main proponents of this view - which was seen as heretical at the time - are believed to have been the Pythagoreans Philolaos, Heraclides, Hicetas, and Ecphantos, but mainly Aristarchos of Samos, who placed the Sun in the po...

Abstract From the earliest years, ancient people considered Earth to be flat, floating on water, in the center of our Solar System and of the Universe. These beliefs generated the so-called geocentric system and the ‘‘holy’’ circular orbits. However, the philosophical ruminations of the ancient Greek philosophers and thinkers questioned the geocent...