Search results for "material"
showing 10 items of 32550 documents
Numerical studies of transport in complex many-particle systems far from equilibrium
2012
In this Thesis, transport in complex nonequilibrium many-particle systems is studied using numerical master equation approach and Monte Carlo simulations. We focus on the transport of the center-of-mass of deformable objects with internal structure. Two physical systems are studied in detail: linear polymers using the Rubinstein-Duke model and single-layer metal-on-metal atomic islands using a semi-empirical lattice model. Polymers and islands are driven out of thermodynamic equilibrium by strong static and time-dependent external forces. Topics covered in this work include introductions to nonequilibrium statistical mechanics, master equations and computational methods, with construction a…
Unravelling the Intertwined Atomic and Bulk Nature of Localised Excitons by Attosecond Spectroscopy
2021
The electro-optical properties of most semiconductors and insulators of technological interest are dominated by the presence of electron-hole quasi-particles, called excitons. The manipulation of excitons in dielectrics has recently received great attention, with possible applications in different fields including optoelectronics and photonics. Here, we apply attosecond transient reflection spectroscopy in a sequential two-foci geometry and observe sub-femtosecond dynamics of a core-level exciton in bulk MgF2 single crystals. Furthermore, we access absolute phase delays, which allow for an unambiguous comparison with theoretical calculations. Our results show that excitons surprisingly exhi…
4,4'-[Thiophene-2,5-diylbis(ethyne-2,1-diyl)]dibenzonitrile
2008
In the solid state, the title compound, C(22)H(10)N(2)S, forms centrosymmetric dimers by pairs of non-classical C-H⋯S hydrogen bonds linking approximately coplanar mol-ecules. The benzene ring involved in this inter-action makes a dihedral angle of only 7.21 (16)° with the thio-phene ring, while the other benzene ring is twisted somewhat out of the plane, with a dihedral angle of 39.58 (9)°. The hydrogen-bonded dimers stack on top of each other with an inter-planar spacing of 3.44 Å. C-H⋯N hydrogen bonds link together stacks that run in approximately perpendicular directions. Each mol-ecule thus inter-acts with 12 adjacent mol-ecules, five of them approaching closer than the sum of the van …
Start talking! : a communicative material package for the upper secondary school oral English course
2016
Suullisen kielitaidon opetus etenkin lukiossa on saanut viime aikoina paljon huomiota osakseen. Tästä huolimatta suullinen kielitaito jää valitettavan usein muiden kielitaidon osa-alueiden varjoon, mikä saattaa osaltaan johtua siitä, että ylioppilaskokeessa sitä ei arvioida. Tällä hetkellä käytössä olevissa oppikirjoissa olevat suulliset harjoitukset eivät aina anna oppilaille mahdollisuutta harjoittaa vapaata suullista tuottamista, vaan vaativat tiettyjen kielimuotojen käyttöä ja keskittyvät esimerkiksi sanaston ja kieliopin harjoittelemiseen. Sellaisia tehtäviä, joissa oppilaiden käyttämä kieli muistuttaa oikeaa kielenkäyttötilannetta, ei ole läheskään tarpeeksi. Tämän oppimateriaalin pää…
A cookbook for hungry teachers : suggestopedy and cooperative learning in practising oral skills : a material package
2008
Teaching specialised vocabulary in a communicative way
2017
Työn tarkoituksena on tutkia ammatillisen erikoissanaston opettamisen kysymyksiä tavoitteena laatia sopivaa opetusmateriaalia intensiivikurssille, joka on tarkoitus pitää Ikean myyntihenkilökunnalle. Sanaston opettamisen lisäksi kurssin toisena ja yhtä tärkeänä tavoitteena on parantaa työntekijöiden englannin kielen puheen sujuvuutta ja sitä kautta itseluottamusta käyttää englantia työssä. Työ koostuu teoriaosasta, jossa haetaan sopivimpia lähestymistapoja ja opetusmenetelmiä ammattisanaston opettamiseksi ja suullisen kielitaidon parantamiseksi, sekä opetusmateriaalipaketista, johon on koottu valikoima sopivia harjoituksia ja tehtäviä, jotka perustuvat teoriaosassa valitulle teoreettiselle …
New charge transfer salts of two organic π-donors of the tetrathiafulvalene type with the paramagnetic [Cr(NCS)6]3- anion
2003
cited By 9; International audience; The electrochemical combination of the paramagnetic anion [Cr(NCS)6]3- with the organic π-donors bis(ethylenedithio)tetrathiafulvalene (ET) and 4,5-bis(2-hydroxyethylthio) -4′,5′-ethylenedithiotetrathiafulvalene (DHET-EDTTTF) leads to two new radical cation salts, namely (ET)4 [Cr(NCS 6]·PhCN 1 and (DHET-EDTTTF)2 (NEt4)[Cr(NCS)6] 2. Both have been characterized by X-ray crystallography, magnetic and resistivity measurements. The structure of 1 consists of alternating inorganic layers generated by the anions and organic layers in which the PhCN molecules are inserted; the organic sub-lattice is built up from four different ET units, three of them with a ch…
Blue Emitting Organic Light Emitting Diodes
2019
Organic light emitting diodes (OLEDs) [1] can be fabricated on a range of materials such as glass, silicon or flexible plastic substrates. This can be exploited for the realization of integrated OLED-based fluorescence chemical sensors [2] and microfluidic systems [3] for application in areas such as biotechnology, life sciences, pharmaceuticals, public health and defense. These devices hold promises to be cost effective, ultra-compact (including the possibility to be fabricated into large bidimensional arrays), and capable to handle smaller sample volumes in order to achieve high throughput. Blue light is advantageous because it is strongly absorbed by most sensing molecules attached to bi…
The Relation between Photoconductivity Threshold and Open-Circuit Voltage in Organic Solar Cells
2022
Financial support provided by Scientific Research Project for Students and Young Researchers No. SJZ/2020/08 implemented at the Institute of Solid State Physics, University of Latvia is greatly acknowledged. Institute of Solid State Physics, University of Latvia as the Centre of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART².
Proton Exchange Membrane Fuel Cells (PEMFCs): Advances and Challenges
2021
The study of the electrochemical catalyst conversion of renewable electricity and carbon oxides into chemical fuels attracts a great deal of attention by different researchers. The main role of this process is in mitigating the worldwide energy crisis through a closed technological carbon cycle, where chemical fuels, such as hydrogen, are stored and reconverted to electricity via electrochemical reaction processes in fuel cells. The scientific community focuses its efforts on the development of high-performance polymeric membranes together with nanomaterials with high catalytic activity and stability in order to reduce the platinum group metal applied as a cathode to build stacks of proton …