Design of potential NO-synthase inhibitors on the basis of 2-amino-5,6-dihydro-4<Emphasis Type="Italic">H</Emphasis>-1,3-thiazine derivatives

Two spiro analogues of 2-amino-5,6-dihydro-4H-1,3-thiazine, a known NO-synthase inhibitor, were synthesized by means of cyclization of N-2-(1-cyclohexenyl)ethylthioureas.     

Separate re-entrant superconductivity in asymmetric ferromagnet/superconductor/ferromagnet trilayers

The superconducting and magnetic states of asymmetric ferromagnet/superconductor/ferromagnet (F/S/F′) nanostructures have been investigated using the boundary value problem for the Eilenberger function. It has been shown that 0- and π-phase superconducting states of pure thin F/S/F′ trilayers are controlled by the magnitude and sign of electron correlations in the F and F′ layers, as well as by the competition between homogeneous Bardeen-Cooper-Schrieffer (BCS) pairing and inhomogeneous Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) pairing. The LOFF-BCS-LOFF separate re-entrant superconductivity has been predicted for F/S/F′ trilayers. A continuous control of the pair-breaking factor in the Eilenberger function and transition to the state with re-entrant superconductivity is achieved by varying the thickness of the F′ layer. Sine-modulated 2D LOFF states in asymmetric F/S/F′ trilayers are possible not only for parallel, but also for antiparallel orientations of the magnetizations of the F and F′ layers; this fact significantly facilitates the experimental implementation of the predicted phenomena.     

Energy spectrum of (Sn0.65Pb0.35)0.95Ge0.05Te solid solutions

The paper reports the study on the resistivity ρ and thermoemf S of the (Sn_0.65Pb_0.35)_0.95Ge_0.05Te solid solution layers. The dependences of ρ and S on the hole concentrations in the range 3×10¹⁹–2×10²¹ cm^?3 exhibit jumps in the resistivity and thermoemf minima at close hole concentrations p ₁≈9×10¹⁹ cm^?3, p ₂≈2.5×10²⁰ cm^?3, and p ₃≈4.5×10²⁰ cm^?3. The observed jumps and minima suggest a complex structure of the valence band and the presence of critical points in the energy spectrum of holes. According to the data for SnTe, the critical points in the energy spectrum at the given hole concentrations are identified as the Σ-extremum, saddle point LΣ, and Δ-extremum, respectively.     

NMR line shape in anisotropic superconductors in a tilted magnetic field

NMR line shape has been constructed for anisotropic type-II superconductors in tilted magnetic fields, with inclusion of vortex-lattice magnetic-field nonuniformities and of the skin effect near the superconductor surface. The NMR line shape parameters are shown to change considerably when the external magnetic field changes direction. This makes it possible to obtain more detailed information about the characteristics of a superconductor, in particular, its anisotropy parameter. Fiz. Tverd. Tela (St. Petersburg) 40, 993–997 (June 1998)     

π-phase magnetism in ferromagnet-superconductor superlattices

New 0π and ππ Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) states with antiferromagnetic orientation of magnetizations in the neighboring layers of a ferromagnetic metal (FM) are predicted for FM/superconductor (FM/S) superlattices. Under certain conditions, the critical temperature T _c of these states is higher than for the known 00 and π0 LOFF states with ferromagnetic ordering of the FM layers. It is shown that the nonmonotonic behavior of T _c in the FM/S superlattices with S-layer thickness d _s less than the threshold value d _s ^π is due to the phase transition cascade 0π-ππ-0π At d _s >d _s ^π , the T _c oscillations are caused by the 00-π0-00 transitions. New logic elements based on the FM/S structures and combining the advantages of the superconducting and magnetic data-record channels in a single sample are proposed.     

New Multifunctional Agents Based on Conjugates of 4-Amino-2,3-polymethylenequinoline and Butylated Hydroxytoluene for Alzheimer’s Disease Treatment

New hybrids of 4-amino-2,3-polymethylenequinoline with different sizes of the aliphatic ring linked to butylated hydroxytoluene (BHT) by enaminoalkyl (7) or aminoalkyl (8) spacers were synthesized as potential multifunctional agents for Alzheimer’s disease (AD) treatment. All compounds were potent inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with selectivity toward BChE. Lead compound 8c, 2,6-di-tert-butyl-4-{[2-(7,8,9,10- tetrahydro-6H-cyclohepta[b]quinolin-11-ylamino)-ethylimino]-methyl}-phenol exhibited an IC₅₀(AChE) = 1.90 ± 0.16 µM, IC₅₀(BChE) = 0.084 ± 0.008 µM, and 13.6 ± 1.2% propidium displacement at 20 μM. Compounds possessed low activity against carboxylesterase, indicating likely absence of clinically unwanted drug-drug interactions. Kinetics were consistent with mixed-type reversible inhibition of both cholinesterases. Docking indicated binding to catalytic and peripheral AChE sites; peripheral site binding along with propidium displacement suggest the potential of the hybrids to block AChE-induced β-amyloid aggregation, a disease-modifying effect. Compounds demonstrated high antioxidant activity in ABTS and FRAP assays as well as inhibition of luminol chemiluminescence and lipid peroxidation in mouse brain homogenates. Conjugates 8 with amine-containing spacers were better antioxidants than those with enamine spacers 7. Computational ADMET profiles for all compounds predicted good blood-brain barrier distribution (permeability), good intestinal absorption, and medium cardiac toxicity risk. Overall, based on their favorable pharmacological and ADMET profiles, conjugates 8 appear promising as candidates for AD therapeutics.     

New tetrasubstituted thioureas containing the 1-iminoethyl moiety

The reactions of 1,1,3-trisubstituted thioureas with acetonitrile afforded the corresponding tetrasubstituted thioureas containing the N-(1-iminoethyl) moiety.