Magnetic field effects on emission and current in Alq3-based electroluminescent diodes

The light output and the current driving tris-(8-hydroxyquinolinato) aluminum (III) (Alq₃)-based light-emitting-diodes were found to increase by up to 5% and 3%, respectively, as an external magnetic field increased to 300 mT. The positive magnetic-field effects were sensitive to the applied voltage. These observations made clear that the emissive singlet exciton formation proceeds via a correlated electron–hole pair state and the excitonic injection of electrons contributes to the driving current, the concentration of singlet excitons being modulated by the hyperfine scale magnetic-field-dependent mixing of singlet and triplet pair states constituting precursors of molecular excitons.     

Operator renewal theory for continuous time dynamical systems with finite and infinite measure

We develop operator renewal theory for flows and apply this to obtain results on mixing and rates of mixing for a large class of finite and infinite measure semiflows. Examples of systems covered by our results include suspensions over parabolic rational maps of the complex plane, and nonuniformly expanding semiflows with indifferent periodic orbits. In the finite measure case, the emphasis is on obtaining sharp rates of decorrelations, extending results of Gouëzel and Sarig from the discrete time setting to continuous time. In the infinite measure case, the primary question is to prove results on mixing itself, extending our results in the discrete time setting. In some cases, we obtain also higher order asymptotics and rates of mixing.     

Concurrent estimation of montelukast and loratadine mixture in spiked human plasma utilizing high-performance thin-layer chromatography with ultraviolet detection

JPC – Journal of Planar Chromatography – Modern TLC - A novel, fast, and cost-effective high-performance thin-layer chromatography (HPTLC) with reflectance/absorbance densitometry was...     

The Mineral Composition of Date Palm Fruits (Phoenix dactylifera L.) under Low to High Salinity Irrigation

Adaptability to salinity varies between different varieties of date palm trees. This research aims to explore the long-term impact of different salinity irrigation levels on the mineral content of 13 date palm varieties grown in the United Arab Emirates (UAE). Date varieties were grown using three irrigation water salinity levels of 5, 10 and 15 dS m⁻¹. The mineral composition (B, Ca, Cu, Fe, K, Mg, Na, P and Zn) of date palm fruits was determined using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). High salinity levels showed no effect on the mineral content of Ajwat AlMadinah, Naghal, Barhi, Shagri, Abu Maan, Jabri, Sukkari and Rothan varieties. All date varieties remained good sources of dietary potassium, magnesium, manganese and boron even at high salinity levels. Increased salinity had no effect on the percent Daily Value (%DV) categories of most of the analyzed minerals. While no genotypes showed a general adaptation to different saline environments, Barhi, Ajwat Al Madinah, Khinizi, Maktoumi and Shagri varieties were more stable towards salinity variation. In the UAE, the genotype x saline-environment interaction was found to be high which makes it impossible to attribute the variation in mineral content to a single varietal or salinity effect.     

Isolation and characterization of two new drimanes from Zygogynum baillonii and synthesis of analogues

Two new drimanes were isolated and characterized from the bark of Zygogynum baillonii, an endemic New-Caledonian tree of the Winteraceae family. One of it shows a significant cytotoxic activity. In order to define structure-activity relationships, analogues were synthesized and their cytotoxicity was evaluated.     

New mesogenic 1,3,4-oxadiazole derivatives

The synthesis of novel liquid-crystalline heteroaromatic compounds incorporating the five membered 1,3,4-oxadiazole ring is described. Due to the bent molecular structure of the oxadiazole ring their mesophase stability is low if the heterocyclic ring occupies a central position, but it is increased if this ring is shifted to a terminal position. Dielectric measurements indicate that the 2-n-alkylthio substitutes 1,3,4-oxadiazole derivatives change the sign of the dielectric anisotropy at the phase transition from the nematic to the smectic A phase. This effect is explained by the increase of the antiparallel correlation of the molecules on formation of the smectic layers.     

Sonochemistry of antitumor quinones in argon-saturated aqueous solutions: enhanced ferricytochrome c reduction

Sonolysis of argon-saturated aqueous antitumor quinone solutions resulted in an enhancement in ferricytochrome c (Cyt c) reduction. Partial inhibition of these reduction enhancements by addition of superoxide dismutase evidences the production of superoxide ions. No correlation between quinone hydrophobicity or redox potential is observed in the extent of Cyt c reduction. The semiquinone of the parent quinone as well as other quinone-derived reductants are proposed as the electron shuttle intermediates which reduce Cyt c.     

Sol-gel synthesis and study of neodymium substitution effects in Co-Al-Nd-O system with possible applications as novel inorganic pigments

In the present work, the formation of cobalt aluminium spinel (CoAl₂O₄) as well as novel cobalt neodymium-aluminates with nominal compositions of CoAl_1.75Nd_0.25O₄, CoAl_1.5Nd_0.5O₄ and CoA_lNdO₄ by an aqueous sol-gel process and the sinterability of the products are investigated. The metal ions, generated by dissolving starting materials of metals in the diluted acetic acid were complexed by 1,2-ethanediol to obtain the precursors for the mixed metal ceramics. The phase purity of the synthesized compounds was characterized by powder X-ray diffraction analysis and infrared spectroscopy. The microstructural evolution and morphological features of the products were studied by scanning electron microscopy and atomic force microscopy, which together with the optical characterization of these new compounds showed that the sol-gel-derived materials could be successfully used as effective cobalt-based ceramic pigments.      

Effective chiral recognition among ions in polar media

Effective homochiral recognition occurs between the cationic [Fe(eilatin)3]2+ complex and TRISPHAT anions even in polar media such as 90% acetone-CHCl3 (de > or = 89%).     

Structure of the oxidized active site of galactose oxidase from realistic in silico models

A systematic in silico approach is employed to generate an accurate model for the catalytically important oxidized state of galactose oxidase (GO) using spectroscopically calibrated hybrid density-functional theory. GO displays three distinct oxidation states: oxidized [Cu(II)-Y*], semireduced [Cu(II)-Y], and fully reduced [Cu(I)-Y], but only the [Cu(II)-Y*] and the [Cu(I)-Y] states are assumed to be involved in catalysis. We have developed multiple models for the oxidized [Cu(II)-Y*] state, whose structure has not yet been fully characterized. These models were evaluated by comparison of calculated and experimental structural data, singlet-triplet energy gaps, and electronic transitions for the antiferromagnetically coupled oxidized [Cu(II)-Y*] state. An extended model system that includes explicit solvent molecules and second coordination sphere residues (R330, Y405, and W290) is essential to obtain the correct electronic structure of the active site. The model with all the residues that have been shown to affect the radical stability and catalysis resulted in a singlet ground state with the radical centered on the Y272-C228 cofactor. The optimized structure of the oxidized GO [Cu(II)-Y*] reveals a five-coordinated square pyramidal coordination geometry very similar to [Cu(II)-Y] with considerably different Cu-ligand distances. The hydrogen-bonding interactions involving Y495 modulates the spin density distribution and the singlet-triplet energy gaps. The final model as the most reasonable structure of the oxidized [Cu(II)-Y*] state in GO reproduces the spectroscopic signature of oxidized GO.