Symmetric Bent-core Liquid Crystals of Some Schiff Bases Containing Azo Linkage

The paper presents the synthesis and liquid crystalline properties of some new symmetric bent-core liquid crystals containing a 1,3-dihydroxybenzene central core disubstituted with mesogenic units consisting of three aromatic rings connected through esteric, azomethinic and azo groups. The wings are ended with terminal acyloxy or alkyloxy chains containing 6 to 10 carbon atoms. Compounds were ob¬tained by the condensation reactions between some 4-((4-alcanoyloxyphenyl)azo)benzaldehydes or 4-((4-alkyloxyphenyl)azo)benzaldehydes with the 1,3-phenylene bis(4-aminobenzoate) core. The new synthe-sized compounds were characterized from structural point of view (1H NMR, 13C NMR, MS spectrosco¬py) and liquid crystalline properties (polarizing optical microscopy and differential scanning calorimetry). All the banana shaped compounds presented enantiotropic liquid crystalline properties, with a wide-ranging stability of mesophases both on heating and cooling cycles. The synthesized compounds present¬ed a good thermal stability in the existence range of the mesophases as evidenced by thermogravimetric studies. (doi: 10.5562/cca2150

Bent-Core Liquid Crystals: Structures and Mesomorphic Properties

Bent-core (BC) molecules became an attractive liquid crystal class due to their potential use in smart displays and photonic devices. In contrast to calamitic mesogens, bent-shaped mesogens are self-organized superstructures with remarkable properties, given the presence of polar order in mesophases, although the molecules themselves are not chiral. A particular interest represents the biaxial nematic liquid crystal materials that are used in display technology and allow a faster switching response, compared to calamitic liquid crystals, with considerably reduced costs. This chapter briefly reviews the bent-core liquid crystals with three different core units in the structure: (1) 2,5-disubstituted oxadiazole, (2) 1,3-disubstituted benzene, and (3) 2,7-disubstituted naphthalene. To the central bent units (BUs) containing reactive functional groups of phenolic or aminic type, various mesogenic groups are symmetrically or asymmetrically connected, via esterification or condensation reactions. The obtained compounds showed biaxial nematic and/or smectic mesophases with high transition temperatures in the case of oxadiazole derivatives or cholesteric and banana-type mesophases with lower transition temperatures in the case of benzene and naphthalene derivatives

Foreign Direct Investment and Competitiveness of Automotive Sector in Romania

The paper approaches the automotive sector in Romania as a main branch of industry that contributes to the country's competitiveness. There is analysed in territorial plan the layout of foreign direct investment and domestic investment in the automotive sector and also the automotive clusters and the main investments made in this sector of the economy. The research also includes an analysis regarding the competitiveness of the automotive sector and presents its evolution in terms of production and exports. The results indicate that most of the investors are located in the west and south of the country, the sector is one of the most competitive areas of economy, contributing to around a quarter of the country's total exports

Unsymmetrical banana-shaped liquid crystalline compounds 1 derived from 2,7-dihydroxynaphtalene

The synthesis and characterization of new bent-core asymmetric compounds derived from 2,7-dihydroxynaphtalene with various connecting groups between the aromatic rings and alkyloxy terminal substituents at the end of the long arm are presented. As calamitic promesogenic units some 1,4 - disubstituted phenylene rings with azo or ester linkage between them have been used. The synthetic strategies to obtain the final esteric derivatives involved the esterification of 7-(benzyloxy)naphthalen-2-ol with 4-(4-alkyloxyphenylazo)benzoyl chlorides or with 4-((4- (alkyloxy)benzoyl)oxy)benzoic acids in the presence of DCCI and DMAP. The mesomorphic properties have been assigned by optical polarizing microscopy and differential scanning calorimetry. All the compounds showed mesomorphic properties of enantiotropic or monotropic type, the liquid crystalline behavior depending on the linking group between the phenylene rings. Thermogravimetric studies evidenced that all compounds were stable in the range of the existence of mesophases

Research and Science Today No. 1(7)/2014

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PROMEHS Kurikul za promicanje mentalnoga zdravlja u vrtićima i školama: Priručnik za odgajatelje i učitelje u svrhu promicanja mentalnoga zdravlja djece u dobi od 3. do 10. godine

Svrha ovog priručnika je primjena PROMEHS kurikula za mentalno zdravlje djece u vrtićima i školama, konkretno za rad odgajatelja I učitelja s djecom i učenicima u dobi od 3. do 10. godine. Sadržajno obuhvaća metodičko- didaktički prikaz aktivnosti koje odgajatelji i učitelji razredne nastave mogu provoditi s ciljem osnaživanja mentalnoga zdravlja, otpornosti i socijalno-emocionalnih kompetencija djece i učenika. Aktivnosti prikazane u priručniku provode se u sklopu postojećih kurikula dječjih vrtića i osnovnih škola kao suvremeni program za promociju i prevenciju teškoća iz područja mentalno zdravlja djece I učenika, a sadržajno i metodički su povezani s priručnikom za djecu I učenike

PROMEHS Kurikul za promicanje mentalnoga zdravlja u vrtićima i školama: Priručnik za odgajatelje, učitelje i nastavnike u svrhu promicanja vlastitoga mentalnoga zdravlja

Svrha ovog priručnika je primjena PROMEHS kurikula za vlastito mentalno zdravlje odgajatelja, učitelja I nastavnika. Sadržajno obuhvaća suvremene teorijske spoznaje te praktične implikacije za osnaživanjem vlastitoga mentalnoga zdravlja kod odgojno- obrazovnih djelatnika. Pritom, također obuhvaća tri važna područja: podruje socijalno- emocionalnih kompetencija, otpornosti i mentalnoga zdravlja