Frumkin Institute of Physical Chemistry and Electrochemistry

The article reports on the development of a fundamentally new, effective technology for recycling waste tires using the explosive-circulation technology method, which was implemented in industry at a working factory. The construction of an explosion-circulation reactor, in which tires are destroyed under the influence of an explosion, is described. The main technological stages of the reactor operation include the formation of a tire package with a height of about 2.4 m and a mass of up to 1000 kg; cooling the package by air turbo-cooling machine to a temperature of minus 70–80 °C; placing the package into the reactor; initiating the explosive charge; and removing the tire shedding products with a subsequent granulometric classification of the resulting rubber crumb. The resulting rubber crumb has good wettability, which eliminates the need for an additional technological stage of activating the crumb surface. This made it possible to successfully use the obtained rubber crumb to improve the characteristics of road construction bitumen, the hardness of which at −16 °C decreased from 217 to 161 MPa. Using atomic force microscopy (AFM), gas chromatography, mass spectrometry, GPC, and XPS, it was established that the good wettability of the crumbs is explained by the formation of molecules with polar groups (C-O, C=O, C(O)O, C-S, C-SOx, Zn-S, O-Si(O)-O) on the crumb surface as a result of the explosion.

Measurement of the Casimir forces at distances smaller than 50 nm is a complicated problem. The method of adhered cantilever does not suffer from loss of stability at short distances and was used recently to measure the adhesion energy due to the dispersion forces with a precision of 10%. In this paper the most important source of errors related to inhomogeneity of the thickness of the cantilevers is discussed. Analytical expressions for the shape of an inhomogeneous cantilever and the adhesion energy are derived. It is demonstrated that monitoring of the cantilever thickness along its length allows five times improvement of the precision. A small twisting of the cantilevers is indicated as an additional source of important errors. This parameter controls the precision of equilibrium average distance between the surfaces and the true adhesion energy between parallel plates.

This study employed a multifactorial analysis, varying Alumina concentration, spinning distance, and applied voltage, to fabricate polyvinyl alcohol/Alumina nanocomposite mats via electrospinning, with the aim of controlling and optimizing fiber thickness. A two-factor interaction model was identified as the best fit for the data, achieving a high coefficient of determination (R² = 0.98). The morphological characteristics of the electrospun mats were assessed through scanning electron microscopy to measure the average fiber diameter (AFD) for each mat. Results indicated that applied voltage has the most pronounced effect on AFD, with fiber diameter decreasing as voltage increases. According to the model, the optimal conditions for producing the thinnest fibers are an Alumina concentration of 1.9%, a spinning distance of 19 cm, and a voltage of 25 kV. Under these conditions, the predicted and actual AFD values were 186 nm and 178 nm, respectively, demonstrating correlation accuracy within acceptable error margins. Fibers prepared under optimal conditions were further characterized using TEM/EDX, FTIR, XRD, biocompatibility testing, and contact angle measurements. These analyses revealed that incorporating Alumina enhances the hydrophobicity and water resistance of electrospun PVA fibers.

Porous carbons based on activated reduced graphene oxide (rGO) have been demonstrated as excellent sorbents for U(vi), with their sorption capacity correlating with the degree of their oxidation. Herein, we demonstrate an extraordinarily high U(vi) sorption of ∼7050 μmol g⁻¹ for super-oxidized porous carbon (SOPC) with a specific surface area (SSA) of ∼970 m² g⁻¹ and an extremely high degree of oxidation (C/O = 2.1), similar to graphene oxide. The SOPC materials were prepared using an oxidation treatment applied to activated carbon produced from spruce cones. The extremely high SSA of the precursor activated carbon (∼3400 m² g⁻¹) as well as its microporous structure and mild oxidation treatment allowed for the preservation of a significant part of the surface area, providing materials with rather narrow pore size distribution (∼7.5 Å). The SOPC prepared from spruce cone biochar is similar to defective graphene oxide but with a significantly higher surface area, resulting in superior U(vi) sorption. Analysis of EXAFS and XPS data shows that U(vi) likely binds to carboxylic groups on the opposite sides of the micropores. The small size of the micropores and irregular pore wall structure are the main factors affecting pore sorption. The spruce-cone biochar has a strong advantage compared with earlier used rGO as a precursor for the preparation of SOPC.

Carbon nanomaterials incorporating metal ions are promising nanozymes, that is, artificial analogs of natural enzymes. Among the previously synthesized carbon dots (CDs) modified with ethylenediaminetetraacetic acid (EDTA) complexes, CDsEDTA-M (M = Fe3+, Cu2+, Ni2+, and Co2+), a pronounced peroxidase-mimicking activity was found for CDsEDTA-Fe. In vitro studies demonstrated low toxicity of CDsEDTA and CDsEDTA-Fe and confirmed the peroxidase-mimicking activity of CDsEDTA-Fe. The influence of the metal ion (M = Fe3+, Cu2+, Ni2+, and Co2+) on the peroxidase-mimicking catalytic activity of CDsEDTA-M was assessed using density functional theory calculations of the model H2O2 reduction reaction involving [M • EDTA] complexes.

The prediction confidence is one of the goals of any machine learning‐based study with no respect if this is distinguished as the aim of the study or is the associated desired concomitant. The possibility do not import the additional error into the pre‐experimental estimation of the studied characteristics should be the goal of machine learning‐based approaches in any case limited in their accuracy by the precision and confidence of the experimental data. The representation theory and information geometry come to the fore to achieve the stated desiderates. In this study, the approaches related to the input consistency regularization are considered which may provide with the required enhancement in the prediction confidence and are able to recoup the part of the experimental error associated with obtaining the data using the methods of different precision or with the discrepancy in the results obtained. The methodology of regularization of the input data consistency is considered in this study in relation to the problem of the predictive modeling of the functional characteristics of A2M3O12${\rm A}_{2} {\rm M}_{3}{\rm O}_{12}$ family of ceramics with negative/close‐to‐zero thermal expansion (NTE or ZTE) properties. It is showed that using diffusion models as the input consistency regularization procedure allows one to achieve the reduction in predictive error for about thirty percent in its absolute value. The Hessian‐based analysis of the loss function landscape is considered as the criterion of the generalizability and model performance. The continuity of the property change as a function of the data description coupled with the analysis of p‐values for the experiment‐prediction output are considered as the auxiliary criteria concerned with the input consistency regularization.

Brachytherapy, or internal radiation therapy, is a highly effective treatment option for localized tumors. Herein, injectable and biodegradable metal-organic frameworks (MOFs) were engineered to deliver the therapeutic radioisotope yttrium-90 (90Y)....

Background: The operation of radioactive waste (RAW) pools is associated with potential environmental risks. Remediation of adjacent territories represents a priority in the Strategy for Environmental Safety of the Russian Federation. Aim: To determine the characteristics of a biogeochemical anti-migration barrier created for the remediation of aquifers with complex contamination, as well as to assess the effectiveness of this barrier. Materials and methods: The elemental composition of samples was determined by inductively coupled plasma mass spectrometry (ICP-MS); the method of capillary gel electrophoresis (CGE) was used to determine the ion concentration. Results and discussion: Maximum concentrations of ammonium, sulfates, uranium, and nitrates in RAW filtration zones are 448, 1800, 4.9, and 10,000 mg/L, respectively. As a result of bioremediation, iron partially passes into sulfide phases, while the remained iron re-precipitates into hydroxide phases during bio- or reoxidation. Purification yielded a chemically active mineral sediment preventing the spread of U, Np, Pu, and Tc redox-sensitive radionuclides, as well as Sr and Am. Conclusion: An effective and economically feasible approach to the purification of groundwater near nuclear fuel cycle facilities during their operation and post-mothballing periods has been tested. The tested method involves the in situ intensification of microbial processes by introducing soluble sources of organic carbon and phosphorus.

This study investigated the behaviour of nanoscale thorium dioxide in a sodium phosphate buffer under hydrothermal conditions under conditions ranging from weakly acidic (pH ∼ 5) to weakly basic (pH ∼ 8). The hydrothermal syntheses yielded a nanosized hydrated double sodium-thorium phosphate phase. The acidity of the medium affected particle size and elemental composition of the product. The phase, identified in all cases as a hydrated variant of the known sodium-thorium phosphate NaTh2(PO4)3, possesses a framework structure and is able to accommodate water and sodium cations within the channels; notably, the sodium content varied based on the acidity of the synthesis medium. Calcination of the nanosized phase in air produced mixtures of two distinct crystalline sodium-thorium phosphates, NaTh2(PO4)3 and Na2Th(PO4)2, in different ratios. The final product composition was determined by the pH used during synthesis and the related phosphate content of the nanosized phase. Characterization of the materials before and after calcination was carried out with a range of complementary methods: X-ray diffraction, small-angle X-ray scattering, electron microscopy, X-ray absorption spectroscopy, total X-ray scattering with pair distribution function analysis, infrared spectroscopy and 31P MAS NMR.