Search results for "SCOT"

Tristriazolotriazines: Luminescent Discotic Liquid Crystals

2018

Synthesis and Characterization of Fluorescent, Low-Symmetry Triphenylene Discotic Liquid Crystals:  Tailoring of Mesomorphic and Optical Properties

1996

A series of monofunctionalized triphenylene-based discotic liquid crystals were synthesized starting from 2-hydroxy-3,6,7,10,11-pentakis(pentyloxy)triphenylene. These compounds are unique in that they possess a single electron-withdrawing group (and consequently a large dipole moment) connected directly to the polyaromatic core. All of the new liquid crystals show a significantly broader range of mesogenicity relative to the parent compound 2,3,6,7,10,11-hexakis(pentyloxy)triphenylene. Moreover, some of the new mesogens exhibit a more ordered mesophase relative to the hexagonal columnar phase (Dh) at lower temperatures. Monofunctionalization of the triphenylene core has a dramatic effect on…

Photoconductivity in Discotic Liquid Crystals: A New Class of High-Mobility Materials

1994

Abstract Using a time-of-flight technique, different transport mechanisms, deep trapping, multiple shallow trapping and Gaussian transport, can be observed in the different temperature and phase regions of the liquidcrystalline (LC) photoconductor hexapentyloxytriphenylene (HPT). Transient photocurrents and carrier mobilities for various temperatures, electric fields, and sample histories were examined. The ideal intrinsic Gaussian transport, observed for holes in the mesophase, puts HPT into a new class of highmobility materials with both hole mobilities on the order of 1.10−3cm2/Vs and a steplike current decay. These features result from the fact that there is obviously neither a position…

On Antarctoscyphus (Cnidaria, Hydrozoa), a new genus of antarctic hydroids and the description of two new species

1997

A new genus of the hydroid family Sertulariidae is established. Several species formerly assigned to the genus Symplectoscyphus Marktanner-Turneretscher, 1890 are included. A review of those species is given, including their main features along with some remarks. Two species new to science are added; the material of those species was collected in the Scotia Sea by the Spanish Antarctic Expedition “Antartida 8611”. Present autecological data are discussed.

Le memorie ingarbugliate. Tensioni autobiografiche nell’Uva puttanella e in Contadini del Sud di Scotellaro

2016

L’intervento s’inserisce nel dibattito sull’autobiografismo di Scotellaro nelle sue due maggiori opere in prosa, arrivateci incomplete e non pronte per la pubblicazione:Contadini del Sud e, soprattutto, L’uva puttanella, che Scotellaro definiva in fase di preparazione un ‘‘romanzo’’. Se Contadini del Sud, nelle parti disponibili oggi, sembra anticipare alcuni esiti dell’attuale non-fiction per via dell’uso disinvolto del materiale documentario, del risalto dato alle testimonianze e alle ricognizioni sul campo, della creazione di veri e propri ‘‘personaggi’’ a tutto tondo che si esprimono direttamente sulla pagina, L’uva puttanella ha caratteristiche che ne sottolineano invece l’inattualita`…

‘Acting-out’ dynamics : Can physical manipulation foster building of mental models from animation?

2016

International audience; The effects of (i) learner demonstration (using a manipulable model) and (ii) writing for understanding on learning from an animation of a Scotch Yoke mechanism were compared in a time-controlled investigation. Post-tests assessed the quality of the Scotch Yoke mental model acquired in the two learning conditions. On the basis of the Animation Processing Model (Lowe & Boucheix, 2008), we hypothesized that participants in the demonstration condition should outperform those in the writing condition because having to demonstrate the behaviors of the Scotch Yoke would result in deeper processing of crucial dynamic information in the animation. Results of the investigatio…

Long-Term Effects of Climate Warming on Forest Soil Collembola

2005

Long-term changes in the collembolan community structure were studied in a Scots pine forest in northern Latvia over a period of 11 successive years (1992–2002). Soil Collembola were yearly sampled from three pine forest stands of different age – young (30 to 40 years old), middle-aged (50 to 70 years old) and old (150 to 200 years old). During the study period a statistically significant increase in sums of positive temperatures (>+4°C) was recorded and a gradual decrease in species richness of Collembola was observed in all forest stands. The study showed that sums of positive air temperatures produce statistically significant effects on collembolan populations. Community responses were s…

Climate-tree-growth relationships of Scots pine stands (Pinus sylvestris L.) exposed to soil dryness

1998

Dendroclimatological techniques were used to assess the impact of climatic factors on radial tree growth (total ring-width and latewood-width) of stunted Scots pine trees (Pinus sylvestris L.) exposed to soil dryness and nutrient deficiency on a dolomite substrate. The response of eight scattered populations representing various habitats, yet influenced by the same regional climate was investigated. Total ring-width and latewood-width were dated, standardized and several chronology statistics, which estimate the chronology signal strength and the potential climate signal in the series, were determined. Dendroclimatic analysis comprised evaluation of event/pointer years as well as response f…

Transient photoconductivity in a discotic hexagonal plastic crystal

1996

Discotic Liquid Crystals - A New Class of Fast Photoconductors

1993

We showed for the first time that discotic liquid crystals are well suited for a new class of fast photoconducting materials. Due to their spontaneous orientation and their dynamical fluctuations in the mesophase, they show exceptionally high mobilities of 1·10−3 cm2/Vs, about two to three orders of magnitude higher than those obtained for conventional amorphous polymers. Further on, the Gaussian transport (for holes in the mesophase) is remarkable, which is characterized by the existence of a conduction band and the absence of trapping states. In contrast, the charge carrier transport in amorphous photoconductors is generally trap-dominated which limits technical properties, leading to low…