The synthesis of cyclic and acyclic long‐chain arylpiperazine derivatives of salicylamide as serotonin receptor ligands

The 1‐arylpiperazine series of N‐substituted 1,3‐benzoxazine‐2,4‐diones as well as O‐ and N‐substituted salicylamides with an n‐propyl chain were synthesized in order to explore the effect of cyclic and acyclic salicylamide moieties on their binding affinity for 5‐HT_1A, 5‐HT_2A and 5‐HT₇ receptor sites. Target compounds 1 and 2 were prepared by a two‐step procedure, i.e. by alkylation of 1,3‐benzoxazine‐2,4‐dione or salicylamide with 1,3‐dibromopropane and next by condensation of 3‐bromopropyl intermediates with arylpiperazines; syntheses of 3‐bromopropyl intermediates were performed in solvent‐free conditions. Compounds 3 were prepared by hydrolysis of 1 . In respect of salicylamide moieties, binding affinities for 5‐HT_1A and 5‐HT₇ receptors increase according to the rank of derivatives 3 < 1 < 2 , for the same arylpiperazines. Regarding 5‐HT_2A receptors, increased activity of ligands was changed in reverse order to the affinity for 5‐HT_1A, i.e. 2 < 1 < 3 . 5‐HT_1A and 5‐HT₇ receptor binding constants were the highest for the 2‐methoxyphenyl ligand 2c , while the 3‐chlorophenyl ligand 3b was most active for 5‐HT_2A receptors.     

Assessment of immobilized yeast for the separation and determination of platinum in environmental samples by flow-injection chemiluminescence and electrothermal atomic absorption spectrometry

The yeast Saccharomyces cerevisiae immobilized in calcium alginate beads was used for separation and subsequent determination of Pt in environmental samples by flow-injection chemiluminescence (FI-CL) and electrothermal atomic absorption spectrometry (ETAAS). The application of a yeast column resulted in an increase in the tolerable matrix ions concentration compared to direct measurements by both detection techniques. The developed FI-CL method of Pt determination based on the catalytic effect of Pt(IV) ions on luminol oxidation in alkaline medium is characterized by a low limit of detection (0.15 ng mL^?1), and good sensitivity and precision, and can be used for analysis of Pt in water samples. Determination of Pt in more complex environmental samples can be carried out by ETAAS (LOD?=?6 ng mL^?1) after introduction of a column clean-up step with 10 mM nitric acid. The accuracy of the method was confirmed by analyzing the certified reference material of platinum ore (SARM-7), spiked grass, and road dust samples.     

Direct observation of the active center for methane dehydroaromatization using an ultrahigh field 95Mo NMR spectroscopy

The use of an ultrahigh magnetic field spectrometer and 95Mo isotope enrichment facilitate the direct observation of the local structure of Mo species on Mo/zeolite catalysts by 95Mo NMR. Top trace: The experimental 95Mo NMR spectrum of 6Mo/HZSM-5. Bottom traces: The simulated overall spectrum (orange), the spectral component corresponding to MoO3 (purple), and the component corresponding to the exchanged Mo species (green). The exchanged Mo species proved to be the active center for the methane dehydroaromatization (MDA) reaction.     

Reaction kinetics study of short DNA strands using a maximum entropy method and nonlinear curve fitting

It is important to understand the formation of double-strand DNA (dsDNA) in a salt solution because it is one of the key reactions in life. A short cDNA strand pair was designed, and each single-strand DNA (ssDNA) was attached to a fluorescent dye that was either a donor or an acceptor of fluorescence resonance energy transfer. The fluorescence intensity was expected to change as time passed as the complementary pairs of ssDNAs formed dsDNAs. The concentration of dsDNA was theoretically calculated, and the measured data were consistent with theoretical results. The analysis of the nonlinear fitting method and the maximum entropy method detected that the reaction curve contains two major types of kinetics that likely represent the formation of dsDNA and mismatching.     

Molecular organization of the antifungal and anticancer drug 2-(2,4-dihydroxyphenylo)-5,6-dichlorobenzothiazole in solution and in monolayers: an effect of pH

2-(2,4-Dihydroxyphenylo)-5,6-dichlorobenzothiazol (dHBBT) is a new anticancer, antifungal and antibacterial drug characterised also by cytostatic and anticancer activity. The effect of pH on the molecular organization of dHBBT in monomolecular layers and in solution has been studied by electronic absorption and FT-IR spectroscopies. The analysis of the spectroscopic data suggests that at neutral and at high pH values (pH 6-8) dHBBT appears in the anionic form that prevents the formation of dimers due to the electrostatic repulsion between the molecules.     

Evidence for pygmy and giant dipole resonances in 130Sn and 132Sn

The dipole strength distribution above the one-neutron separation energy was measured in the unstable 130Sn and the double-magic 132Sn isotopes. The results were deduced from Coulomb dissociation of secondary Sn beams with energies around 500 MeV/nucleon, produced by in-flight fission of a primary 238U beam. In addition to the giant dipole resonance, a resonancelike structure ("pygmy resonance") is observed at a lower excitation energy around 10 MeV exhausting a few percent of the isovector E1 energy-weighted sum rule. The results are discussed in the context of a predicted new dipole mode of excess neutrons oscillating out of phase with the core nucleons.     

Why the phase shifts for solitons on a vortex filament are so large: a theoretical explanation

The phase "jumps" for solitons interacting on a vortex filament, observed in experiments, have been unaccounted for for more than 20 years. Using explicit formulas describing the interaction of two solitons on a thin vortex filament in the localized induction approximation, we show that an appropriate choice of the parameters of the solitons leads to large phase shifts. This result does not depend on the axial flow along the filament.     

Triplet-Triplet-Absorption einiger carbonylhaltiger Verbindungen

Ohne Zusammenfassung     

Energy transfer between two beams in writing a reflection volume hologram in a dynamic medium

A theoretical study is presented of the stationary energy transfer between two beams in the writing of a reflection hologram in a dynamic medium. The intensities of the two beams both inside the medium and at the surfaces are determined as a function of absorption coefficient, the effective coupling constant, the initial intensity ratio and the thickness of the medium. Numerical results obtained from the computer calculations are presented in graphical form.