Tetra­potassium dianti­mony(III) tin(IV) tetra­deca­fluoride

The title compound, K4Sb2SnF14, is built from anionic layers, with an overall composition of [Sb2SnF14]4− extending parallel to the ac plane, and K+ cations. The layers are made up from vertex-sharing centrosymmetric SnF6 octa­hedra and Sb2F12 dimers. The Sn—F distances are in the range 1.9581 (14)–1.9611 (17) Å. The Sb polyhedra contain three short terminal Sb—F bonds [1.9380 (14)–2.0696 (15) Å], one short bridging bond [2.0609 (17) Å], one bridging bond of medium length [2.7516 (15) Å], and two longer bridging bonds [3.0471 (18) and 3.117 (2) Å]. The K+ ions are coordinated by F atoms with coordination numbers 10 and 8, and K—F bond lengths are in the range 2.6235 (16)–3.122 (2) Å

Order and Frustration in Chiral Liquid Crystals

This paper reviews the complex ordered structures induced by chirality in liquid crystals. In general, chirality favors a twist in the orientation of liquid-crystal molecules. In some cases, as in the cholesteric phase, this favored twist can be achieved without any defects. More often, the favored twist competes with applied electric or magnetic fields or with geometric constraints, leading to frustration. In response to this frustration, the system develops ordered structures with periodic arrays of defects. The simplest example of such a structure is the lattice of domains and domain walls in a cholesteric phase under a magnetic field. More complex examples include defect structures formed in two-dimensional films of chiral liquid crystals. The same considerations of chirality and defects apply to three-dimensional structures, such as the twist-grain-boundary and moire phases.Comment: 39 pages, RevTeX, 14 included eps figure

OSOBENNOSTI POKAZATELEY UL'TRASONOMETRII ZhENSKOGO NASELENIYa GORODA ChELYaBINSKA

Characteristic feature of ultrasonic densitometry have been investigated in women,s population of Chelyabinsk (n=200) from 25 to 65 years old. We used domestically produced Echoosteometr-02. A basis of a body of the lower jaw became a new area for ultrasonic densitometry. We can recommend a lower jaw as a new area for ultrasonic densitometry taking into account high pithiness of data in a combination with simplicity of research. Traditional localizations have been also applied: proximal phalanges of the hand, patella, tibia diaphysis and calcaneus bones of the right and left sides. We have established a "peak" values of a speed of the ultrasound wave for the given bones. Also we have found that a tubular bones and a large spongy bone - a lower jaw - possess the highest speed of an ultrasound wave, and the speed was mach less in a small spongy bones, that is caused by their anatomic structure. Ultrasound densitometry parameters of the peripheral skeleton start to reduce from 40-50 years behind exception patella - from 55 years. The lowest values were in group of women of 60-65 years. The rates of ultrasonic densitometry received by us are possible to use for women population of Chelyabinsk

Mesomorphic Properties and Computer Simulation of Guanazole Derivatives and Their Mixtures

An investigation of the mesomorphic properties of 3,5-diamino-1-dodecyl-1,2,4-triazole and 3-amino-1,5-dodecyl-1,2,4-triazole binary mixture in the ratio of 1:0.75 (four molecules of the first compound and three of the second) was performed. By means of polarizing optical microscopy, it was discovered that the experimentally obtained binary mixture possesses enantiotropic mesomorphic properties (SmA phase). With the help of the molecular dynamics simulation of both individual triazole derivatives and their binary mixture, it was shown that the SmA-mesophase is caused by the presence of the di-dodecyl substituted triazole derivative

Mesomorphic Properties and Computer Simulation of Guanazole Derivatives and Their Mixtures

An investigation of the mesomorphic properties of 3,5-diamino-1-dodecyl-1,2,4-triazole and 3-amino-1,5-dodecyl-1,2,4-triazole binary mixture in the ratio of 1:0.75 (four molecules of the first compound and three of the second) was performed. By means of polarizing optical microscopy, it was discovered that the experimentally obtained binary mixture possesses enantiotropic mesomorphic properties (SmA phase). With the help of the molecular dynamics simulation of both individual triazole derivatives and their binary mixture, it was shown that the SmA-mesophase is caused by the presence of the di-dodecyl substituted triazole derivative

Floating layers and thin films of mesogenic mix-substituted phthalocyanine holmium complex

The supramolecular organization of the A$_3$B-type phthalocyanine holmium complex (A3B–Ho) was investigated in floating layers at the air–water interface and in Langmuir-Schaefer thin films at the air–solid interface. The floating layers formed under different experimental conditions on the water subphase using the Langmuir technique. They were studied by Brewster angle microscopy, grazing incidence X-ray diffraction and X-ray reflectometry. It was established that molecules of A$_3$B–Ho form stable ordered floating monolayer on the water surface. Experimental conditions required for this monolayer formation were determined as following: the initial degree of coating of the water surface was 18%, the compression rate of barriers was 6 cm$^2$/min and the surface pressure was 0.4 mN/m. Under these conditions a stable crystalline monolayer structure was obtained with an area per one molecule 3.9 nm2. It has a two-dimensional face-on packing with the intralayer period of 2.06 nm. The Langmuir-Schaefer thin film was obtained on the basis of the above mentioned monomolecular floating layer. The film possesses a single two-dimensional structure with the packing of the molecules parralel to the substrate surface that was revealed by electron diffraction. The lattice parameters of the monomolecular film were $a$ = 1.65 nm, $b$ = 1.92 nm, $\gamma_1$ = 75. It was shown that the film preserves the structure of the floating monolayer