Search results for " Dono"

Red- and Blue-Shifts in Oligo(1,4-phenyleneethynylene)s Having Terminal Donor−Acceptor Substitutions

2004

Four series of oligo(1,4-phenyleneethynylene)s (OPEs), 1−4 (a−d), each having a terminal dialkylamino group as their electron donor, were prepared by applying Sonogashira−Hagihara reactions and a protecting group strategy. To study the influence that the push−pull effect has on the long-wavelength absorption, three of the four series of OPEs contain terminal acceptor groups (CN, CHO, NO2). Extending the conjugation (increasing the number of repeat units, n) lowers the energy E(n) of the electron transition in the purely donor-substituted series 1a−4a (bathochromic shift). This effect is superimposed in the push−pull series 1−4 (b−d) by the effect of the intramolecular charge transfer (ICT),…

Selenophene-Based Hole-Transporting Materials for Perovskite Solar Cells

2021

Two novel and simple donor-π-bridge-donor (D-π-D) hole-transporting materials (HTMs) containing two units of the p-methoxytriphenylamine (TPA) electron donor group covalently bridged by means of the 3,4-dimethoxyselenophene spacer through single and triple bonds are reported. The optoelectronic and thermal properties of the new selenium-containing HTMs have been determined using standard experimental techniques and theoretical density functional theory (DFT) calculations. The selenium-based HTMs have been incorporated in mesoporous perovskite solar cells (PSCs) in combination with the triple-cation perovskite [(FAPbI3 )0.87 (MAPbBr3 )0.13 ]0.92 [CsPbI3 ]0.08 . Limited values of power conver…

Photoinduced Single Electron Transfer on 5-Aryl-1,2,4-oxadiazoles:  Some Mechanistic Investigations in the Synthesis of Quinazolin-4-ones

1999

The photochemistry of some 5-aryl-3-methoxy- (or 5-aryl-3-phenyl-) 1,2,4-oxadiazoles irradiated in the presence of different sensitizers [such as diphenylacetylene (DAC), 9,10-diphenylanthracene (DAN), or triphenylene (TPH)] or ground-state donors such as triethylamine (TEA) has been investigated. Intermediates arising from breaking of the ring O-N bond develop both into quinazolin-4-ones (by a heterocyclization reaction involving the aryl at the C-5 of the oxadiazole nucleus) and into open-chain products (corresponding to a reduction at the ring O-N bond), in different ratios depending on their structures and photoreaction conditions. A reasonable explanation considers sensitization by pho…

ChemInform Abstract: Photoinduced Single Electron Transfer on 5-Aryl-1,2,4-oxadiazoles: Some Mechanistic Investigations in the Synthesis of Quinazoli…

2010

The photochemistry of some 5-aryl-3-methoxy- (or 5-aryl-3-phenyl-) 1,2,4-oxadiazoles irradiated in the presence of different sensitizers [such as diphenylacetylene (DAC), 9,10-diphenylanthracene (DAN), or triphenylene (TPH)] or ground-state donors such as triethylamine (TEA) has been investigated. Intermediates arising from breaking of the ring O-N bond develop both into quinazolin-4-ones (by a heterocyclization reaction involving the aryl at the C-5 of the oxadiazole nucleus) and into open-chain products (corresponding to a reduction at the ring O-N bond), in different ratios depending on their structures and photoreaction conditions. A reasonable explanation considers sensitization by pho…

Orgānu un audu izņemšana no cilvēka - cilvēktiesību pārkāpums?

2017

Darbā “Orgānu un audu izņemšana no cilvēka – cilvēktiesību pārkāpums?” tiek izpētīta likumīga cilvēka orgānu un audu transplantācija, kā arī nelikumīga orgānu un audu izņemšana, kas ir neatļauta un noziedzīga darbība. Orgānu un audu izņemšanas cilvēktiesību jautājums saasinājās pēdējo 40 gadu laikā, sakarā ar zinātnes attīstību transplantācijas jomā un cilvēktiesību lomas pieaugumu medicīnas un pacientu tiesībās. Tāpēc bakalaura darbā autore apskata orgānu un audu izņemšanas juridiskās īpatnības un tas rezultātā radītos cilvēktiesību aizskārumus. Orgānu un audu izņemšanas problēma mūsdienās ir ļoti svarīga un izplatīta, jo orgānu un audu pieprasījums ir lielāks nekā orgānu piedāvājums, tāpē…

Synthesis, characterization and magnetic study of two new octahedral iron(III) complexes with pendant zwitterionic Schiff bases

2016

Two Schiff bases, HL1 [2-((3-(dimethylamino)propylimino)methyl)-5-bromophenol] and HL2 [2-((2-(diethylamino)ethylimino)methyl)-6-methoxyphenol], have been employed to prepare two new octahedral iron(III) complexes, [Fe(HL1)2(N3)2]ClO4·2H2O (1) and [Fe(HL2)2(NCS)2]ClO4·H2O (2). Both complexes are characterized by spectral and elemental analyses. Single crystal X-ray diffraction studies confirm their structures. In both complexes, Schiff bases are trapped in their zwitterionic forms and coordinated to iron(III) only through the imine nitrogen and phenoxo oxygen, i.e., they behave as bi-dentate ligands, keeping the remaining potential donor sites pendant. The measurement of χM vs. T for both c…

Forme e logiche di reciprocità in Erodoto e Tucidide

Questo studio mira ad analizzare le differenti forme e funzioni che l’etica della reciprocità assume nella cultura greca del V secolo a.C., in particolare in Erodoto e Tucidide. La reciprocità è una componente essenziale delle relazioni umane su cui la cultura greca ha elaborato una riflessione attenta. Questo principio morale costituisce una delle primarie forme di applicazione della giustizia nelle relazioni sociali; il suo ruolo si può indagare nell'ambito dei rapporti interpersonali e parimenti nelle relazioni interstatali. Si tratta di un sistema etico che ha delle radici profonde nel pensiero e nel costume greco, pertanto l'indagine su questo tema offre una chiave d'accesso privilegia…

Etty Hillesum: kairòs e dono assoluto

2002

Ab initio calculations of Nb doped SrTiO3

2010

We present and discuss the results of the large scale Hartree–Fock calculations of Nb impurities substituting for Ti ions in SrTiO3 using ab initio computer code CRYSTAL and several supercells containing up to 135 atoms. The local structure optimisation, the electronic charge redistribution, chemical bond covalence and the band-structure changes induced by the defect are analysed. According to the results of our calculations, Nb is a shallow donor; six nearest O ions are slightly displaced outwards from the Nb ion. The calculated bond population between nearest Ti and O ions (64 me) is much larger than that between Nb and O ions (8 me), since Nb impurity is more ionic than the host Ti.

Prolactin supplementation to culture medium improves beta-cell survival

2010

OBJECTIVES.: Recent studies demonstrated that prolactin (PRL) has beneficial effects on β cells for islet transplantation. We examined the effect of human recombinant PRL (rhPRL) supplementation to the culture media to determine its potential use in the context of clinical islet transplantation. MATERIALS AND METHODS.: Each human islet isolated from 14 deceased multiorgan donors was cultured in Miami modified media-1 supplemented with or without rhPRL (500 μg/L) for 48 hr. β-Cell survival and proliferation (BrdU and Ki-67) were determined by laser scanning cytometry. The cytoprotective effects of rhPRL against noxious stimuli were assessed by flow cytometry (tetramethylrhodamine ethyl ester…