Realization Conditions and the Magnetic Field Dependence of Corner Excitations in the Topological Insulator with Superconducting Coupling on the Triangular Lattice

Journal of Experimental and Theoretical Physics - The studies of the topological properties of systems have recently been extended due to a new concept of higher-order topological insulators and...     

Acoustic properties of the disordered relaxor ferroelectric PbSc1/2Ta1/2O3

The behavior of acoustic phonons in crystals of a relaxor ferroelectric, namely, the lead scandium tantalate PbSc_1/2Ta_1/2O₃ (PST), is studied in the vicinity of the diffuse phase transition. The behavior of longitudinal and transverse acoustic phonons in a PST single crystal is examined using Brillouin scattering. The phonon subsystem is found to behave anomalously in the vicinity of T = 297 K, which can probably be assigned to the existence of a phase transition. Analysis of the results obtained yields the values of the elastic moduli C₁₁, C₁₂, and C₄₄ for the cubic phase of the crystal over a wide temperature range.     

A new, fast and efficient synthesis of 3-aryl indenones: intramolecular cyclization of 1,3-diarylpropynones in superacids

1,3-Diarylpropynones were cleanly converted to the corresponding 3-arylindenones in various superacidic media. This new, simple, one-pot reaction proved to be efficient (yields up to 95%) and very fast (reaction time less than 30 min).     

A census of semisymmetric cubic graphs on up to 768 vertices

A list is given of all semisymmetric (edge- but not vertex-transitive) connected finite cubic graphs of order up to 768. This list was determined by the authors using Goldschmidt's classification of finite primitive amalgams of index (3,3), and a computer algorithm for finding all normal subgroups of up to a given index in a finitely-presented group. The list includes several previously undiscovered graphs. For each graph in the list, a significant amount of information is provided, including its girth and diameter, the order of its automorphism group, the order and structure of a minimal edge-transitive group of automorphisms, its Goldschmidt type, stabiliser partitions, and other details about its quotients and covers. A summary of all known infinite families of semisymmetric cubic graphs is also given, together with explicit rules for their construction, and members of the list are identified with these. The special case of those graphs having K_1,3 as a normal quotient is investigated in detail. Supported in part by N.Z. Marsden Fund (grant no. UOA 124) and N.Z. Centres of Research Excellence Fund (grant no. UOA 201) Supported in part by “Ministrstvo za šolstvo, znanost in šport Slovenije”, research program no. 101-506. Supported in part by research projects no. Z1-4186-0101 and no. Z1-3124-0101. The fourth author would like to thank the University of Auckland for hospitality during his visit there in 2003.     

The fixed point property in ordered sets of width two

We consider the fixed point property (FPP) in an ordered set of width two (every antichain contains at most two elements). The necessary condition of the FPP and a number of equivalent conditions to the FPP in such sets is established. The product theorem is proved, as well.     

The synthesis of 3,6-diamino-2,3,4,6-tetradeoxy-dl-threo-hexopyranose derivatives,substrates for the synthesis of negamycin

Three synthetic routes to derivatives of 3,6 - diamino - 2,3,4,6 - tetradeoxy - DL - threo - hexopyranose were investigated. Addition of sodium azide in acetic acid to 6 - phthalimido - 5,6 - dihydro - 2 - pyrone gave 4-azido compound (7) of the erythro configuration. From methyl 2,4 - dideoxy - β -dl- erythro - hexopyranoside threo 4 - phthalimido - 6 - phthalimidomethyl - tetrahydro - 2 - pyrone (17) was obtained in three steps in low overall yield. Addition of sodium azide in acetic acid to butyl 6 - oxo - 2 - hydroxy - hex - 4 - enoate followed by methylation, amonolysis of the ester group, and reduction gave methyl 3,6 - diacetamido - 2,3,4,6 - tetradeoxy - α - DL - threo - hexopyranoside (26).     

Preparation of alkyl-containing derivatives of chitosan and its oligomers in polymer-analogous reactions

It has been shown that the interaction of chitosan and oligochitosan with unsaturated acrylic esters via the nucleophilic addition mechanism and their condensation with heptadecyl isocyanate yield hydrophobic alkyl-containing derivatives of the above polymers. The method of modification of oligochitosan in reactions via end functional groups is developed.     

Determination of thallium and lead in cadmium salts by anodic stripping voltammetry with addition of surfactants to suppress the cadmium peaks

Conditions have been found which make possible the determination of thallium and/or lead in cadmium and its salts without preliminary separation. The electrochemical activity of the cadmium, which usually interferes in the determination of thallium, is inhibited by the addition of 0.01% of polyethylene glycol of M.W. 4000. Thallium is determined by electrolysis at ?0.74 V vs. SCE, in 0.1M EDTA solution: 10^?1M thallium can be determined in the presence of 0.1M cadmium, while copper and lead at 10^?2M and 10^?5M respectively do not interfere. Lead is determined in 0.1M acetic acid containing 0.1% cetyltrimethylammonium bromide (CTAB). The addition of CTAB shifts the cadmium peak, as well as the optimum deposition potential for cadmium, to more negative values, making it possible to determine lead in the presence of cadmium as long as the deposition potential lies in the range between ?0.50 and ?0.56 V vs. SCE. Lead can be determined in the presence of ten times as much thallium.     

Hexamolybdoaluminates and Hexamolybdochromates of Some Trivalent Lanthanides and Americium

The reactions of some rare-earth elements (La, Ce, Sm, Lu, Gd) and Am(III) with heteropolymolybdate anions are studied. The complexation rate constants of Am(III) in a solution with Al(OH)₆Mo₆O₁₈ ^3- and Cr(OH)₆MoO₁₈ ^3- ₆ (₁ = 18 ± 6 and 25 ± 5, respectively) are determined by spectral methods. The Ln[Al(OH)₆Mo₆O₁₈] · nH₂O, Eu[Cr(OH)₆Mo₆O₁₈] · nH₂O, and Am[Al(OH)₆Mo₆O₁₈] · nH₂O isostructural compounds are synthesized. The crystal structure of the Sm[Al(OH)₆Mo₆O₁₈] · 11H₂O complex was determined by the X-ray diffraction analysis. The results of spectroscopic and thermogravimetric studies of the obtained compounds are presented.