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Uchenye Zapiski Kazanskogo Universiteta Seriya Estestvennye Nauki

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Vol 166, No 2 (2024)
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187-209 235
Abstract

The process of nanofiltration purification of water from various organic pollutants was examined. Cellophane film made from cheap natural raw materials was used as a membrane. The model substances targeted for removal were dyes (Safranin O, Orange II, and Remazol Brilliant Blue R, each differing in molecular weight, chemical composition, and charge) and ceftriaxone. The obtained cellophane permeability to water was 0.145 kg/(m2∙h∙atm). Cellophane membranes were found to be effective in retaining dissolved anionic substances containing acid groups. When Orange II and Remazol Brilliant Blue R were removed from the water, the retention coefficients were 97 ± 2 and 99 ± 1%, respectively. For the cationic dye Safranin O, the retention coefficient values were negative, –7 ± 3%. At the same time, ceftriaxone had the retention coefficient of only 41 ± 5%, which can be attributed to a combination of factors, such as its high affinity for cellophane and steric restrictions.

210-228 213
Abstract

The conductive properties of CNT/polymer composites have been extensively studied. However, the impact of CNT distribution in the matrix on the composite polarization remains underexplored and poorly understood. Since it is difficult to achieve a uniform distribution of CNTs in polymers, most researchers have focused only on indiscriminately aggregated states. In this article, a new blending method was suggested to prepare a series of epoxy resin-based composite samples with varying levels of CNT uniformity/aggregation and the same filling fractions. Notably, the permittivity values turned out to be inversely related to the composite uniformity: the lowest permittivity values were obtained in the most uniform formulation, and vice versa. With 0.1% CNT, the real part values of the most uniform and aggregated samples were 6.6 and 16.2 at 107 Hz and 11.6 and 370.5 at 101 Hz, respectively. For the filler content of 0.1–0.5%, the conductive properties were largely determined by the distribution of CNTs and not their content. Within the entire frequency range, the uniform sample with 0.2% CNT exhibited significantly lower permittivity than the aggregated sample with 0.1% CNT. These findings emphasize the importance of the aggregation factor and underscore the non-universality and limitations of the percolation theory and power laws. The observed phenomenon is best explained by the micro-capacitor model, or the Maxwell–Wagner polarization, and suggests that a significant portion of the literature in the field needs to be reconsidered.

229-237 210
Abstract

This study aimed to determine the physicochemical properties of coconut flower nectar (CFN) powder produced by spray drying. The powder product of the best sample (with maltodextrin–CFN ratio of 26%, w/v) appeared as white, spherical, or oval particles. Its physicochemical properties were as follows: recovery yield (42 ± 2 %), moisture content (3.1 ± 0.6 %), particle size (3–12 μm), bulk density (0.380 ± 0.006 g mL-1), hygroscopicity (22 ± 2 %), water solubility index (97 ± 1 %), angle of repose (42.2 ± 0.7°), and wettability (366 ± 11 s). The obtained results offer valuable insights for future research on spray drying of food products and pave the way for potential large-scale use of spray-dried CFN in a great variety of products due to easier preservation and longer shelf life.

238-254 266
Abstract

This article considers the effect of protein–starch interaction on the gelling, textural, andsensory properties of keropok lekor used as a fish protein–starch model. A two-level factorial design was employed to analyze the quality and acceptability of different formulations of keropok lekor crackers depending on the ratios of minced fish (MF, 20–50 g (w/w)), sago starch (SS, 10–40 g (w/w)), and water (W, 10–35 g (w/w)). The parameters measured were the onset (T0) and peak (Tp) temperatures of gelatinization, storage modulus (G′), and loss modulus during gelatinization (G″). The samples were rated by a group of 30 panelists during texture profile analysis and sensory evaluation. The most preferred samples had the MF : SS : W ratio of 20 : 10 : 10 and were characterized by the lowest onset and peak temperatures of gelatinization. Therefore, this formulation was singled out as optimal for keropok lekor.

255-265 322
Abstract

Molecular targets for a promising antitumor agent based on trans-stilbene containing a pyridoxine fragment were identified. The lead compound, (E)-6-(3,4-dimethoxystyryl)-2,2,5,8-tetramethyl-4H-[1,3] dioxino[4,5-c]pyridine, was found to selectively induce apoptosis in MCF-7 breast adenocarcinoma cells overexpressing estrogen receptor, but not in MDA-MB-231 cells negative for estrogen receptor. The mechanism by which the novel trans-stilbene derivative acts as a selective estrogen receptor modulator was analyzed, and the affinity for human estrogen receptor α (ERα) was assessed by fluorescence polarization. Unlike its structural analogs—tamoxifen and raloxifene, the lead compound showed no affinity for ERα and did not form complexes with it. Therefore, it was concluded that the selective action of the pyridoxine-containing derivative of trans-stilbene on estrogen-positive breast cancer cells occurs through an alternative mechanism. The EC50 values for the displacement of the fluorescent ligand from the ERα active site were 22, 120, and 595 nM for estradiol, raloxifene, and tamoxifen, respectively.

266-282 197
Abstract

High metal concentrations in the body’s biological substrates often result from a persistent, cumulative impact of adverse environmental conditions. This article considers the quantitative composition of human biological substrates as an indicator of the state of urban ecosystem components. Assessing the accumulation of metals in the body by directly measuring their concentrations in biological substrates is a multi-step analytical procedure. Here, a quick-and-easy method for determining metal concentrations in biological substrates based on a neural network algorithm was introduced. A complex neural network model was developed to enable the determination of metal inputs from the air and food-water system without the need for invasive sampling of biomaterials or too difficult processing and analysis of the samples obtained. The model also proved to be feasible in solving the inverse problems associated with the determination of metal thresholds in various components of urban ecosystems.

283-296 148
Abstract

A model of pharmacological paralysis in the hind limbs of CD-1 mice was introduced. In the initial phase (before paralysis), the activity of MAO-A, a key enzyme of neuroamine metabolism, was inhibited, leading to increased levels of steroid hormones and prolactin, as well as to a decrease in hepatic CYP3A4 and CYP2D6 activities and astrocytic S-100 protein secretion into the blood serum. In the second phase (paralysis manifestation), the mice exhibited hind limb paralysis development, accumulation of cortisol granules, destruction of capillaries, and aggregation of deformed red blood cells in the cerebral cortex and hippocampal regions.

297-311 152
Abstract

Telomeres are highly conserved nucleoprotein structures involved in the defense mechanisms of eukaryotic organisms. Their length depends on a variety of biotic and abiotic factors, such as environmental stressors. Being stationary, plants are particularly susceptible to environmental stresses. This article explores the effects of heat stress on telomere length in Arabidopsis thaliana. Telomere length was measured for individual chromosome arms. It was shown that hyperthermia at 42 °C altered telomere length in some chromosome arms of the wild-type A. thaliana plants, as well as in the long telomeres of the knockout mutants for the gene OLI5/RPL5A. The high temperatures caused the telomeres to become shorter, with the longer telomeres showing a stronger response to the stress. This suggests that the complex regulation of telomere length may be associated with exposure to environmental stressors.

312-323 138
Abstract

Despite the increasing water and sediment pollution in the western part of the Northern Caspian Sea, the quality of its marine environment has never been assessed through bioindication, largely due to methodological issues. In this article, the method of standards, which involves comparing the species composition between the polluted and clean (reference) sites, was used for the bioindication of organic pollutants in the Northern Caspian Sea. The study area was segmented based on isobaths. The segments were determined depending on the range of depths inhabited by zoobenthos species and their ecological valence to oxygen. The depths with a sufficient abundance of oxyphilic zooplankton species (bioindicators) to apply the method of standards were located. The obtained results show that the method of standards is a good and reliable choice to assess the marine environment quality in the Northern Caspian Sea at isobaths of 6–9 m and within depths of 14–18 m for polluted and reference sites. However, the sediments must contain shells, sand, and siltstones. Therefore, while the method of standards has clear merits, it does not suffice for the rest of the Caspian Sea area.

324-341 173
Abstract

Technogenic soils result from the oxidation and hydrolysis of minerals in rocks extracted from mining areas and brought to the surface. Diagnostics of such soils involve a set of detailed tests, which can be both time-consuming and costly. In this study, the pH of sulfate soils in the Kizel Coal Basin (Perm krai, Russia) was determined using hydrogen peroxide. Particularly, the soils affected by runoff from rock dumps, outflow, and mine water discharge were examined. The findings showed pH-H2O2 below 2.5 in certain horizons, indicating the presence of sulfides. Additionally, the soils exhibited significantly higher levels of mobile sulfur and iron, total sulfur, and sulfates, ranging from tens to hundreds of times above the background content. XRD analysis revealed that the soils contained goethite and jarosite, thereby confirming the efficacy of pH determination with hydrogen peroxide for the prompt diagnostics of acid sulfate soils.

342-367 188
Abstract

The protective structures of bryozoans representing four orders—Trepostomata, Cryptostomata, Fenestrata, and Cheilostomata—were analyzed and classified for the first time based on functional criteria. The proposed classification includes five groups of protective structures responsible for: 1) reducing water pressure; 2) increasing the feeding area by expanding the distance between the autozooecia apertures, as well as strengthening the colony’s stability and integrity; 3) physically protecting the polypide and providing attachment points for muscles; 4) scaring off predators; and 5) enabling physical protection against predators while also cleaning the colony from sediments, larvae, and small invertebrates. The study of the development of heterozooids, stylets, and avicularia in fossil bryozoans revealed the emergence of persistent, effective polymorphs in the Early Ordovician, Late Devonian, and Early Cretaceous. The evolutionary changes in bryozoans were primarily driven by fluctuations in the levels of the World Ocean, climate, phytoplankton biomass, and predator composition, among other complex interplays between abiotic and biotic factors. To shield themselves from predation threats, bryozoans evolved acanthostyles protruding above colony surfaces and various types of heterozooids physically protecting them from being eaten (caverno-, para-, cyclo-, lepto-, and allozooids in the old groups, along with avicularia in cheilostomates). Avicularia and similar structures occurred repeatedly in different orders: in fenestrates during the Early Ordovician and Early Devonian, in cryptostomates during the Middle Carboniferous, and in cheilostomates during the Early Cretaceous.



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ISSN 2542-064X (Print)
ISSN 2500-218X (Online)