State Research Institute for Chemistry and Technology of Organoelement Compounds

A connection between the symmetry of high-field nuclear magnetic resonance (NMR) spectra, including higher-order spectra, and the properties of the spin system has been established. It is shown that, for a spectrum to be symmetric about the mid-resonance frequency (), two conditions must be satisfied: (1) the resonance frequencies of the spins must be symmetrically positioned about , and (2) there must exist at least one spin ordering with a monotonic increase (or decrease) in resonance frequencies such that the spectrum is invariant under the reflection of the -coupling matrix about its anti-diagonal (one way to satisfy this condition is for the -coupling matrix to be explicitly persymmetric). The results were validated by calculating theoretical spectra for three-, four-, five-, and six-spin systems.

The use of pulsed acoustic microscopy (50–200 MHz) makes it possible to analyze the three-dimensional microstructure and uniformity of the elastic properties of hydrated composite biomaterials. This paper proposes a method for local assessment of acoustic properties in spongy polymer samples, based on visualizing the microstructure, measuring attenuation, and sound velocity. This approach is relevant to the study of biopolymer composite materials and their structures, as it allows for in situ observation of structural degradation under external influences, as well as investigation of the evolution of native tissue replacement, if necessary.

Lignin, the second most abundant natural polymer, is a by-product of the biorefinery and pulp and paper industries. This study was undertaken to evaluate the properties and estimate the prospects of using lignin as a by-product of the pretreatment of common reed straw (Phragmites australis) with deep eutectic solvents (DESs) of various compositions: choline chloride/oxalic acid (ChCl/OA), choline chloride/lactic acid (ChCl/LA), and choline chloride/monoethanol amine (ChCl/EA). The lignin samples, hereinafter referred to as Lig-OA, Lig-LA, and Lig-EA, were obtained as by-products after optimizing the conditions of reed straw pretreatment with DESs in order to improve the efficiency of subsequent enzymatic hydrolysis. The lignin was studied using gel penetration chromatography, UV-vis, ATR-FTIR, and 1H and 13C NMR spectroscopy; its antioxidant activity was assessed, and the UV-shielding properties of lignin/polyvinyl alcohol composite films were estimated. The DES composition had a significant impact on the structure and properties of the extracted lignin. The lignin's ability to scavenge ABTS+• and DPPH• radicals, as well as the efficiency of UV radiation shielding, decreased as follows: Lig-OA > Lig-LA > Lig-EA. The PVA/Lig-OA and PVA/Lig-LA films with a lignin content of 4% of the weight of PVA block UV radiation in the UVA range by 96% and 87%, respectively, and completely block UV radiation in the UVB range.

Organoalumoxane oligomers modified with refractory metals (zirconium, hafnium or chromium) were synthesized. Their physico-chemical and fiber-forming properties were studied. Models of the group and elemental composition of oligomeric molecules of organoalumoxanes containing zirconium, hafnium or chromium were proposed. Based on the results of X-ray elemental microanalysis (SEM) and X-ray diffraction, it was found that pyrolysis of metal-containing organoalumoxanes at 1500°C in air results in the microcrystalline ceramic powders of corundum composition, modified with refractory metal oxides.

The reactions of hydrogermylation of allylsilanes and -germanes R3MAll (M = Si, Ge; R = Cl, EtO, Me) by hydridogermanes R3GeH (R = Cl, Me) and trichlorogermane etherate 2Et2O·HGeCl3 were studied. It was found that small amounts of mono- (β- and γ-adducts) and double germylation products and, mainly, polymers were formed in the reactions with the etherate. In the case of hydrogermylation of Me3SiAll with trichlorogermane, insignificant amounts of β-adduct were recorded, but in the entire series of the experiments with Cl3GeH mainly γ-adducts were formed. The catalytic reactions of allylsilanes and -germanes with trimethylgermane gave exclusively γ-adducts, irrespective of the framing of the silicon and germanium atoms. A scheme of the possible course of the studied reactions was proposed. The synthesized compounds were identified by gas-liquid chromatography, 1H and 13C NMR spectroscopy, and chromatography-mass spectrometry methods.

Background: Kumaizasa (Sasa senanensis Rehder) is a representative natural plant growing in Hokkaido, Japan, and has a history of being used in herbal medicine and as a health food option. Nishihira et. al. (2019) confirmed in a clinical trial that the kumaizasa dry powder had the effect of improving bowel movements of healthy volunteers. In this study, we evaluated the effect of the components of kumaizasa powder, like holocellulose (hemicellulose + cellulose) and cellulose, involved in the bowel movement of rats and tried to elucidate the role of each component.Methods: Male rats (Slc:SD, weight 79~93 g) were administered kumaizasa powder (3000 mg/kg/day) orally, holocellulose (1500 mg/kg/day), cellulose (900mg /kg/day) or water using a stomach tube twice a day for 14 days.Results: Among the intervention groups (kumaizasa powder, holocellulose, cellulose group) and control group (water), no significant differences were observed with changes in body weight and food consumption. All the feces were normal, with one exception of watery feces on day 2 in the cellulose group. Multigroup comparison by the Tukey-Kramer method showed that the dry weight of feces collected at day 14 in the kumaizasa powder group significantly increased as compared with that of the control group (p<0.01). This result confirmed that kumaizasa powder had the effect of increasing fecal amount. A paired t-test between each kumaizasa group and control group indicated that the cellulose increased the fecal dry weights and moisture content in feces, while the kumaizasa powder and the holocellulose increased only fecal dry weights.Conclusion: It is shown that the holocellulose and cellulose of kumaizasa powder have the effect of increasing the bowel movement of rats by oral administration. It is also suggested that the cellulose increases the moisture content in the feces by swelling, while hemicellulose in the holocellulose acts as a prebiotic to regulate the moisture content in feces.Keywords: Kumaizasa, Sasa senanensis Rehder, hemicellulose, cellulose, holocellulose, bowel movements

The presence of reactive hydrogen-silyl (SiH) bonds in oligomethylhydridesiloxanes provides their widespread use in the building, paper, textile, and rubber industries. Low-molecular fractions of methylhydridesiloxanes, both cyclic and linear, adversely affect the operational properties of oligomer-based materials. The main goal of the present study is detection and identification of these fractions in a 136-157M commercial product, as well as in the co-oligomers synthesized from it. The method of gas chromatography–mass spectrometry has been used in the study. First, it has been proved that an increase in the temperature of the column and evaporator from 60 to 300°C does not change the composition of the low-molecular fractions. Consequently, there is no depolymerization processes related to the formation of low-molecular compounds during the analysis. To perform a qualitative analysis, the components of low-molecular fraction have been separated on a capillary column and then identified using a mass detector with an ion trap. It is shown that electron ionization triggers fragmentation of molecules and the formation of positively charged ions. As for methylhydridesiloxanes, cations with a molecular weight of [M – 15]+ arising from the rupture of the carbon-silyl bond are formed first. When such a rupture occurs in cyclosiloxanes with a total number of units of more than four, further dissociation processes can occur with the detachment of the neutral fragment (methylsilane) and the formation of bicyclosiloxane cations. Since the set of positive ions is individual for each of the components and depends on $${{\left[ {\text{M}} \right]}^{{ + \bullet }}}$$ , a component-wise description of the entire low-molecular fraction becomes possible with a high degree of reliability. It is shown that, for the commercial sample under consideration, it can be described by two homologous series: cyclic $${\text{D}}_{m}^{{\text{H}}}$$ , where m ≥ 4, and linear siloxanes $${{{\text{M}}}_{2}}{\text{D}}_{n}^{{\text{H}}}$$ , where n ≥ 1.

Resumen: El propósito de este trabajo investigativo giró en torno a la implementación de una secuencia didáctica mediante una plataforma interactiva como lo es Classcraft, con el ánimo de trabajar la comprensión lectora del inglés en el nivel literal de los estudiantes del programa de formación complementaria en la ciudad de Sincelejo. Para este fin se estableció el uso de un diseño investigativo mixto de tipo secuencial, relacionándose un método de tipo descriptivo para el enfoque cuantitativo y una investigación acción para el enfoque cualitativo, sobre una población de estudio correspondiente a estudiantes de II semestre del programa de formación complementaria, con muestra no probabilística intencionada. A la luz de las técnicas e instrumentos aplicados se determinaron resultados preliminares diagnósticos relacionados con la percepción del uso de las TIC y los niveles de comprensión lectora del inglés, tomándose como punto de partida para diseñar e implementar secuencias didácticas interrelacionadas con el Classcraft. En definitiva, se contrastan los resultados diagnósticos y los evaluativos concibiéndose la efectividad del Entorno Virtual de Aprendizaje Classcraft como una herramienta interactiva que favorece los niveles de desarrollo de la comprensión lectora del inglés, específicamente el literal, asimismo los procesos de enseñanza y aprendizaje.