The skeleton of spines and tests of the species of sea urchins Strongylocentrotus intermedius, Mesocentrotus nudus, Scaphechinus mirabilis, and Echinocardium cordatum from the Sea of Japan is composed of a spongy stereom, consisting of calcite with a high content of magnesium. It was found that the tests and spines of the skeletons of sea urchins are composed of calcium–organic composite materials inlaid with other metals: Mg, Fe, Zn, and Rb. In the four species of sea urchins studied, the strength and other mechanical properties of the tests and spines differ and depend on the chemical composition and structural organization of their components. It was shown that the content of volatile substances correlates with their fragility or elasticity. It is revealed that the chemical composition of the tests of two species of the spherical sea urchins S. intermedius and M. nudus indicates significant differences between these two species of sea urchins.

We studied a number of chemical characteristics in the coals of the Spetsugli germanium-bearing area of the Pavlovskoe coalfield in southern Primorye. It was found that the coals show variable content

High-purity X-ray amorphous silicon dioxide samples have been prepared by hydrolyzing siliconcontaining plants in a 0.1 N HCl solution, followed by calcination at 700°C in air. Reducing the silica...

The crystal structure of the [Tb(BTFA)₂(NO₃)(TPPO)₂] complex (TPPO is triphenylphosphine oxide, BTFA is benzoyltrifluoracetone), which exhibits strong triboluminescence, has been established by X-ray crystallography. The crystals are triclinic: a = 11.668(3) Å, b = 11.700(3) Å, c = 12.512(3) Å, α = 65.161(4°), β = 79.120(4)°, γ = 61.860(4)°, space group P1, Z = 1. The central terbium(III) atom coordinates two oxygen atoms from two triphenylphosphine oxide molecules (Tb-O, 2.264(3) and 2.273(3) Å), two oxygen atoms from the nitrate group (Tb-O, 2.460(3) and 2.476(3) Å), and four oxygen atoms from two benzoyltrifluoroacetonate groups (Tb-O, 2.329(3), 2.399(3), 2.351(3), and 2.367(3) Å). The coordination polyhedron of the Tb(III) atom is a distorted dodecahedron. The photoluminescence and triboluminescence spectra of the [Tb(BTFA)₂(NO₃)(TPPO)₂] complex are identical and caused by the f-f luminescence of Tb³⁺.

A comparative study of the microscopic morphology and chemical characteristics of spicules of Hexactinellids (Hexactinellida) with different structural features of the skeletons, as well as the freshwater Baikal sponge belonging to the class of common sponges (Demospongia), was carried out. The trace element composition of sponge spicules was determined by X-ray fluorescence spectrometry. The spicules of siliceous sponges contain many elements, arranged in decreasing order of concentration: Si, Ca, Fe, Cl, K, Zn, and others. It was shown that the surface layer of sea sponges contains mainly carbon (C), oxygen (O), and to a lesser extent nitrogen (N), silicon (Si), and sodium (Na). The spicules of the studied siliceous sponges can be divided into two groups according to the phase composition, namely one containing crystalline calcium compounds and one without them. Analysis of infrared absorption spectra allows us to conclude that the sponges Euplectella aspergillum, E. suberia and Dactylocalyx sp. contain silica partially bound to the organic matrix, while the silica skeleton of the sponges of the other group (Schulzeviella gigas, Sericolophus sp., Asconema setubalense, Sarostegia oculata, Farrea sp. and Lubomirskia baicalensis sp.) practically does not differ from the precipitated SiO₂. This comparative study of the chemical composition of the skeletons of marine Hexactinellids and common freshwater sponge allows us to conclude that there are no fundamental differences in the chemical composition of spicules, and all of them can be used as a starting material for creating new composite silicon–organic functional materials.