STM study on the self-assembly of oligothiophene-based organic semiconductors

The self-assembly properties of a series of functionalized regioregular oligo(3-alkylthiophenes) were investigated by using scanning tunneling microscopy (STM) at the liquid-solid interface under ambient conditions. The characteristics of the 2-D crystals formed on the (0001) plane of highly ordered pyrolitic graphite (HOPG) strongly depend on the length of the p-conjugated oligomer backbone, on the functional groups attached to it, and on the alkyl substitution pattern on the individual thiophene units. Theoretical calculations were performed to analyze the geometry and electronic density of the molecular orbitals as well as to analyze the intermolecular interactions, in order to obtain models of the 2-D molecular ordering on the substrate.

Ikasgelan gauzatzen diren gatazkaz ohartuz

Laburpena: Bost urteko gela batean burututako ikerketa lan honen bidez, gure inguruko eskoletan ohikoa den egoera aztertu nahi da. Hots, eskoletan ematen diren gatazka egoerak, hain zuzen ere. Gainera, argi izan behar dugu hauek ondo bideratzen ez badira biolentzia edota agresibitate egoerak bilakatu daitezkeela. Gatazka hauek bi eratan ulertu daitezke: alde batetik, umearen jokabide negatibo gisa; edota, gaiaren inguruko hausnarketa sakona eginez gero, umeak ingurunea ulertzeko eta horrekin interakzioak egiteko erabiltzen dituen ikasketa mekanismo gisa. Argi dago beraz, gatazka hauen izaera parametro ezberdinek osatzen dutela: irakaslearen papera, eskainitako baliabideak, umearen garapena, etab. Ikuspuntu honetatik lanean ikasgelan bizi izandako gatazken ezaugarrien frekuentzia erregistroa egin da. Gatazka hauen interpretazioak haur hezkuntzako irakasleei hobetu ulertzen eta honekin batera, hauek era positibo batean bideratzen lagundu ahal dizkie.

Germanene: a novel two-dimensional germanium allotrope akin to graphene and silicene

We have grown an atom-thin, ordered, two-dimensional multi-phase film in situ through germanium molecular beam epitaxy using a gold (111) surface as a substrate. Its growth is similar to the formation of silicene layers on silver (111) templates. One of the phases, forming large domains, as observed in scanning tunneling microscopy, shows a clear, nearly flat, honeycomb structure. Thanks to thorough synchrotron radiation core-level spectroscopy measurements and advanced density functional theory calculations we can identify it as a root 3 x root 3 R(30 degrees) germanene layer in conjunction with a root 7 x root 7 R(19.1 degrees) Au(111) supercell, presenting compelling evidence of the synthesis of the germanium-based cousin of graphene on gold.

Coincidence point theorems in quasi-metric spaces without assuming the mixed monotone property and consequences in G-metric spaces

In this paper, we present some coincidence point theorems in the setting of quasi-metric spaces that can be applied to operators which not necessarily have the mixed monotone property. As a consequence, we particularize our results to the field of metric spaces, partially ordered metric spaces and G-metric spaces, obtaining some very recent results. Finally, we show how to use our main theorems to obtain coupled, tripled, quadrupled and multidimensional coincidence point results.

Pata contractions and coupled type fixed points

A new coupled fixed point theorem related to the Pata contraction for mappings having the mixed monotone property in partially ordered complete metric spaces is established. It is shown that the coupled fixed point can be unique under some extra suitable conditions involving mid point lower or upper bound properties. Also the corresponding convergence rate is estimated when the iterates of our function converge to its coupled fixed point.