silicon compound
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The reaction of dichlorodimethylsilane with a polydentate Schiff base ligand derived from pyridoxal and 2-ethanolamine yielded the macrocyclic silicon compound (8E,22E)-4,4,12,18,18,26-hexamethyl-3,5,17,19-tetraoxa-8,13,22,27-tetraaza-4,18-disilatricyclo[22.4.0.010,15]octacosa-1(24),8,10,12,14,22,25,27-octaene-11,25-diol, C24H36N4O6Si2. The asymmetric unit contains the half macrocycle with an intramolecular O—H...N hydrogen bond between the imine nitrogen atom and a neighbouring oxygen atom. The crystal structure is dominated by C—H...O and C—H...π interactions, which form a high ordered molecular network.

The article presents data on the long-term effect (nine months) of a silicon compound supplied with drinking water – nonahydrate sodium metasilicate (10 mg/l in terms of silicon), on CD68-positive macrophages in the liver and spleen of laboratory rats. Changes in the morphological characteristics of this cell population were found. There was a decrease in the average cell area (in the liver of the control group of rats, the average macrophage area was 179.23±5.94 microns2, and in the group receiving silicon with drinking water – 117.04±3.35 microns2; in the spleen-136.02±3.93 microns2 and 103.44±2.8 microns2, respectively). Macrophages in the liver preparations of the experimental group of rats had a fewer processes and a darker cytoplasmic membrane. The number of macrophages in the liver per unit area was comparable, for the control group of rats it was 18.78±1.24, and for the rats that received with water with the addition of silicon – 19.41±0.75 cells. CD68+ macrophages of the red splenic pulp in laboratory rats that received silicon also underwent the following morphological changes: they were located in a denser way and had fewer processes, while the number of macrophages per unit area was 73.7±2.3 for the control group, 91.6±5.0-for the experimental group, respectively. The distance between them did not change. There was a change in the intensity of CD68 expression on the surface of the cytoplasmic membrane and in the cytoplasm of liver and spleen macrophages. These changes can be interpreted as the adaptive ability of liver and spleen macrophages to silicon introduced with drinking water. Given the heterogeneity of the macrophage population in the liver and spleen, further studies using markers for different subpopulations of macrophages are needed to clarify their role in the response of tissues to silicon supplied with drinking water.

AbstractStretchable photovoltaics are emerging power sources for collapsible electronics, biomedical devices, and buildings and vehicles with curved surfaces. Development of stretchable photovoltaics are crucial to achieve rapid growth of the future photovoltaic market. However, owing to their rigidity, existing thin-film solar cells based predominantly on silicon, compound semiconductors, and perovskites are difficult to apply to 3D curved surfaces, which are potential real-world candidates. Herein, we present a stretchable micro-scale concentrator photovoltaic module with a geometrical concentration ratio of 3.5×. When perfectly fitted on a 3D curved surface with a sharp curvature, the prototype module achieves an outdoor power conversion efficiency of 15.4% and the daily generated electricity yield improves to a maximum of 190% relative to a non-concentration stretchable photovoltaic module. Thus, this module design enables high areal coverage on 3D curved surfaces, while generating a higher electricity yield in a limited installation area.

This study investigated the fire risk properties of cypress wood for the construction of interiors, especially focusing on heat and smoke hazard properties in fire scenarios. Fire risk characteristics were measured using a cone calorimeter (ISO 5660-1). The external heat flux was maintained at 50 kW/m2. The flame retardants used were metal oxide and metal silicate; they were mixed with a water glass solution. Flame retardants and the silicon compound were dispersed in a concentration of 20 wt% versus 80 wt%, respectively, during 24 h using a magnetic stirrer. The fire performance indexes of the specimens increased by 3–16 times, compared with uncoated specimen and the fire growth index of the specimens increased by 70%–92%. The smoke performance index of the specimens increased by 9–66 times, compared with uncoated specimens. The smoke risk as shown by the smoke performance index increased in the following order: SnO < mica < Co3O4 < ZrSiO4 < cypress. The smoke growth index decreased from 93% to 98%, compared with uncoated wood. The smoke risk due to smoke growth index increased in the following order: SnO < mica < ZrSiO4≈ Co3O4 < cypress. The smoke intensity decreased from a minimum of 85% to a maximum of 99%, compared with uncoated wood. The concentration of CO gas generated after combustion was decreased by 24%–67%. They increased in the following order: mica ≈ ZrSiO4 < SnO < Co3O4 < cypress. A comprehensive assessment of fire performance shows that flame retardants decreased heat hazards, smoke hazards, and CO toxicity.

Silicon dioxide is the most common silicon compound and a major constituent of the Earth’s crust. Silicon dioxide, also known as silica, is a chemical compound that is an oxide of silicon with the chemical formula SiO2. Silica is most commonly found in nature as quartz. Quartz exists in natural and synthetic forms. More specifically α-quartz is a widely known material, which is stable at low temperatures and pressures. The α-quartz is considered competent material because over the past many years it has attracted wide attention due to its unique characteristics. The article presents the research results from comparison between one of the morphological varieties of quartz – vein quartz of shungite rocks from Zazhogino deposit of Karelia – and a reference quartz sample. Via the Rietveld method, the values of the lattice parameters are determined. Apparent coherent length for vein quartz samples having contacts with various minerals are determined by the approximation method.

Silicon (Si) is an element necessary for the proper functioning of the body. It affects cell viability, osteoblast differentiation, blood vessel elasticity, type I collagen synthesis, as well as the condition of the skin, hair, and nails. It is also considered an antiatherosclerotic agent. The silicon content in the human body is 6 – 7 g, and the only absorbable form is orthosilicic acid. The average daily requirement of the body for this element is in the range of 20 to 40 mg, whose diet does not fully provide. In addition, the silicon content in the body decreases with age, so there is a need for its supplementation. There are many liquid, gel, and spray diet supplements available that vary in concentration and silicon compound. The aim of the research was to determine the content of orthosilicic acid in liquid diet supplements. Thirteen preparations were selected for the study, in which concentration of available silicon was determined by a spectrophotometric method. This method was based on reaction in the acidic environment of dissociated silicon with ammonium molybdate. Among the selected products, the highest concentration of available silicon form was obtained for pharmaceuticals composed of choline stabilized orthosilicic acid, which is in the range of 50-2000 ppm. However, its concentration in preparations containing monomethylsilanetriol (MMST) did not exceed 50 ppm. Keywords: chemical sciences, orthosilicic acid, Uv-Vis spectroscopy