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The production and application of activated biochar have demonstrated significant improvements in environmental conditions both locally and across Ukraine. Researchers have confirmed the viability of creating carbon adsorbents specialized for water purification from plant-based materials, streamlining the conversion of organic biopolymers into the final product. Enhancements to traditional pyrolysis technology included the implementation of wet cooling-activation, which facilitated the development of the porous structure in wood biochar. The study further compared the efficiency of various technological solutions by evaluating biochar samples across several criteria in water purification technology. [ABSTRACT FROM AUTHOR]

The most significant and protracted phase of the installation of a dental prosthesis is osseointegration of a metal implant with bone tissue. It is important to accelerate this process, for example, by the use of extracorporeal shock wave therapy. The objective of this study is to investigate numerically the conditions for osseointegration of the implant in the dental region employing a poroelastic model implemented in the movable cellular automaton method. The mandibular segment under consideration includes a spongy tissue covered with a cortical layer 600 μm thick and a gum 400 μm thick. Additionally, the second premolar and second molar exhibited periodontal membranes of their roots, while the implant of the first molar was situated within a shell of soft fibrous tissue. The obtained fields of hydrostatic pressure and interstitial fluid pressure were analyzed according to the mechanobiological principles. The results obtained have indicated that shock wave therapy has a beneficial impact on the creation of conditions conducive to the differentiation and transfer of bone tissue cells along the main volume of the fibrous tissue surrounding the implant during the initial osseointegration stage. [ABSTRACT FROM AUTHOR]

The method of isotherm simulation by approximating mathematical expressions that are valid for a small experimental section of the isotherm over the entire range of equilibrium concentrations is an important and useful tool in adsorption practice. Nine adsorption equilibrium systems of activated carbon (AC)–derivatives of aniline and phenol were examined. The adsorbent used was activated carbon obtained from fruit pits. The results of isothermal adsorption of aromatic substances with relatively small molecules on a microporous carbon adsorbent indicate the simultaneous adequacy of the Freundlich and Langmuir models to the experimental data in moderate concentration ranges ((0.1–100)n mg/dm3, where n = 1, 2, 3, 4, 5). Thus, the results of adsorption from the aqueous phase do not demonstrate the energy differences of the AC surface that are incorporated into the theoretical classical model isotherms. The isotherm reflects the adsorption process on both homogeneous and heterogeneous surfaces simultaneously. This may be due to the displacement nature of adsorption from the aqueous phase, where initial surface screening by water molecules occurs during adsorbent wetting, leading to the leveling of its energetic heterogeneity. In the next stage—displacement of some water molecules by the organic adsorbate—the energetic differences of the adsorption sites are not as clearly manifested as in gas-phase adsorption. Therefore, theorizing the nature of the AC surface based on the best model simulation of experimental isotherms using classical equations becomes questionable. Three-parameter equations (Langmuir–Freundlich, Redlich–Peterson) demonstrated a finer simulation of the experiment compared to the classical two-parameter models. The study emphasizes that the mathematical description of the isotherm is a convenient method for the efficient storage and use of information about the adsorption properties of the system. It serves to compare the effectiveness of new materials with commercial analogs and to predict the performance of real purification systems under dynamic conditions. [ABSTRACT FROM AUTHOR]

Entanglement and coherence are fundamental properties of quantum systems, promising to power near-future quantum technologies, such as quantum computation, quantum communication, and quantum metrology. Yet, their quantification, rather than mere detection, generally requires reconstructing the spectrum of quantum states, i.e., experimentally challenging measurement sets that increase exponentially with the system size. Here, we demonstrate quantitative bounds to operationally useful entanglement and coherence that are universally valid, analytically computable, and experimentally friendly. Specifically, our main theoretical results are lower and upper bounds to the coherent information and the relative entropy of coherence in terms of local and global purities of quantum states. To validate our proposal, we experimentally implement two purity detection methods in an optical system: shadow estimation with random measurements and collective measurements on pairs of state copies. The experiment shows that both the coherent information and the relative entropy of coherence of pure and mixed unknown quantum states can be bounded by purity functions. Our research offers an efficient means of verifying large-scale quantum information processing. [ABSTRACT FROM AUTHOR]

A mechanical metamaterial is considered using mathematical modeling and computer simulation. Its structure consists of tetrachiral elements providing a non-conventional behavior under uniaxial tension/compression. The deformation behavior of the metamaterial is investigated on its solid computer model using the finite element method. A uniaxial loading of the mechanical metamaterial sample is simulated as a quasistatic problem within the linear elasticity theory. Hooke's law for an isotropic material is chosen as the constitutive equation for the base material. A new method of overlapping is proposed for connecting the unit cells of a three-dimensional metamaterial. It allows achieving the maximum twisting effect. The graphs of dependence of the angle of twist and effective Young's modulus on the parameters characterizing the unit cell structure of the metamaterial are presented. [ABSTRACT FROM AUTHOR]

A topological space is called submetrizable if it can be mapped onto a metrizable topological space by a continuous one-to-one map. In this paper we answer two questions concerning sequence-covering maps on submetrizable spaces. [ABSTRACT FROM AUTHOR]

A numerical investigation of the influence of porosity, pore size, and planar defects (microcracks) on the elastic constants, compressive and tensile strength of a fine-grained matrix in a SiO2 refractory ceramics is presented. The modeling results show a qualitatively different effect of the 3D (pores) and 2D (microcracks) defects on its effective elastic properties. An increase in porosity leads to a decrease in Young's modulus and the strength of the refractory matrix, while the trend in the Poisson's ratio behavior depends on the degree of pore structure connectivity. Microcracks also reduce the effective strength and Young's modulus of the matrix but, unlike the pores, they cause an asymmetry in the effective elastic properties. The Young's modulus of the matrix decreases more slowly under compression than under tension, and the Poisson's ratio trend is the opposite (an increase under compression and a decrease under tension). The quantitative estimates of the effective mechanical characteristics of the fine grain matrix can be used in multiscale computer models of traditional and advanced SiO2-based refractories. [ABSTRACT FROM AUTHOR]

Dental implants are becoming an increasingly important part of modern dental treatment. Developing an optimal implant surface design can improve osseointegration. Promising to increase the rate of osseointegration is the use of extracorporeal shock wave therapy, which has proven itself for the treatment of fractures, bone defects, and bone tissue regeneration during surgery and arthroplasty. This work aims at a numerical investigation of the effects of low-energy shock wave therapy of various intensities on the mechanical behavior of dental implants and surrounding bone tissues, taking into account the physiological characteristics in the area of dental implant placement. Modeling was carried out using the method of movable cellular automata. The results of computer simulation showed that the conditions for the regeneration of bone tissues at the near-contact zone with the implant of the jaw segment are created by a shock wave with intensity greater than 0.1 mJ/mm2. [ABSTRACT FROM AUTHOR]

Abstract—The article considers the efficiency and possibility of introducing into operation of VVER-1000 power units with the lifetime extended owing to the sliding pressure of the second circuit. The history of research by Russian nuclear engineers on VVER lifetime extension is reviewed. It is shown that reduction of fresh steam pressure within the allowed limits will make it possible to release additional reactivity through release of the temperature effect and to generate additional energy during the period of unit operation on the power effect. A mathematical model of changes in the main parameters of the reactor unit, including reactivity balance equations, Stodola–Flugel equation for the turbine, and heat balance and heat transfer equations in the steam generator, is compiled. The expected increase in power generation for modern fuel loadings of VVER-1000 reactors is calculated. The degree of compliance of the proposed mode with the current technological limitations of the large-series VVER-1000 power units is analyzed. The results of the analysis are confirmed by the numerical experiment on the multifunctional analyzer of the VVER-1000 unit modes developed by the National Research Nuclear University MEPhI built on the basis of the ENICAD environment and the certified diffusion neutronic code PROSTOR. Conclusions are drawn about the possibility of introducing the proposed mode into the operational practice of modern VVER-1000 power units. [ABSTRACT FROM AUTHOR]

This paper presents the numerical and experimental results of hardening of an annular zone on the flat surface of an X20Cr13 steel specimen by friction stir processing (FSP) with a WC-Co hard alloy tool moving along circular and fan-shaped paths. A finite element model of the process is proposed for predicting the temperature distribution through the width and depth of the annular zone for the considered tool paths and for detecting the reverse tempering regions. The influence of the paths of a cylindrical friction stir tool with a flat end on microhardness distribution in the surface layer of the hardened zone was studied experimentally. It was shown that FSP along the fan-shaped path provides uniform hardening of the annular zone, while processing along the circular trajectory leads to softening of the material in the regions where the friction tracks overlap. The uniformity of surface hardness in the friction stir processed annular zone of X20Cr13 steel was evaluated by calculating the "covering uniformity" (CU) index proposed by Campana. The hardening behavior is in full agreement with the results of finite element simulation of the FSP process. Hardness measurements and microstructural studies showed that the fan-shaped tool path provides surface layer hardening to a depth of 400 μm with the CU index ranging from 0.78 to 1.00. In the case of the circular path, the CU index ranges from 0.48 to 0.72 at the same depth. The proposed research methods can be applied to evaluate the FSP efficiency when using other workpiece and tool materials. [ABSTRACT FROM AUTHOR]

We proposed to evaluate the performance of new adsorption materials in relation to existing commercial products by comparing the values of the standard molar adsorption energy of of adsorbates. A typical error in the determination of is due to the incorrect calculation of the adsorption equilibrium constant Ke. It is often calculated in isothermal regions that do not correspond to standard adsorption conditions, or the dimensional constant of the Langmuir model equation KL is falsely used as a thermodynamic constant. The direct use of the Langmuir constant KL as an equilibrium constant is a thermodynamically invalid approach; however, due to the simplicity of determining KL, an estimate of the adsorption energy based on it can become an accessible and useful tool for adsorption studies. In this work, we examined two methods to transform the Langmuir constant into surrogate constants, which, according to formal features, are dimensionless quantities and reflect the conditional energy of adsorption. We selected 16 adsorption systems of activated carbon (F300, KAU, KAU/Fe, Akant) with aqueous solutions of sparingly soluble aromatic compounds of the phenol and aniline series. We compared the adsorption energy values obtained from the Langmuir constant and the thermodynamically verified constant of the partial adsorption isotherm, calculated by the procedure developed by A.M. Koganovskii (the Koganovskii method, KM). The deviations of the adsorption energy values calculated from the Langmuir constant are on average 10–15% compared to the results obtained by the Koganovskii method. To plot the adsorption isotherms of aromatic compounds, a simplified algorithm for calculating Ke according to the KM was proposed and tested (without considering the volume of the adsorption phase and the molar volume of adsorbents). Deviations in energy values were within 5% of the KM results. Thus, the considered simplified methods are easy to implement and accurate enough to estimate the standard adsorption energy; therefore, they can be recommended for the initial assessment of the effectiveness of new adsorption materials. [ABSTRACT FROM AUTHOR]

A new mathematical model was proposed using an ordinary differential equation that analytically (when the index of geomagnetic activity Kp = const or Kp ≈ const) or numerically (if Kp(t) ≠ const) describes perpendicular (for a pitch angle of 90°) differential or integral fluxes of relativistic electrons in a geostationary (geosynchronous) orbit, as well as in any circular orbit in the Earth's magnetosphere. The model assumes that the fluxes depend on the local time LT in orbit, the Kp, McIlwain parameter L and the perpendicular differential flux or integral flux of relativistic electrons taken at 00 LT. We use observations of relativistic (>2 MeV) electron fluxes averaged over the local hour along the orbit of the GOES spacecraft from 1995 to 2009. The model is compared with these data. Almost perfect agreement was obtained for observations with the model, where the prediction efficiency of accuracy of the model at PE = 0.9989. Using similar data from the GOES 10 allows one to obtain PE = 0.9924. The proposed formulas make it possible to find, for example, the average value of the perpendicular integral flux of relativistic electrons per day and to predict the maximum perpendicular integral flux of relativistic electrons in the geostationary orbit approximately 1 day ahead. The nonlinear effect is theoretically predicted in the form of a nonlinear dependence of the ratio of the maximum perpendicular integral flux to the minimum flux of charged particles in the geostationary orbit from the Kp-index of geomagnetic activity. Thus far, comparison of the model has been made with the averaged integral relativistic electron fluxes produced for the 0 ≤ Kp < 6 range with a predicted maximum flux ratio of 24.4139 times at Kp = 8 and with the prediction efficiency of accuracy of the nonlinear effect = 0.8678. [ABSTRACT FROM AUTHOR]

Additive manufacturing allows fabricating materials with complex structures and specific properties. For Cu-Al alloys that are widely used in the sliding friction units of many machines in different industries, the 3D printing technique using electron beam-induced deposition seems to be very promising due to its great possibility in fabricating materials with varied compositions and gradient structure. The material structure and its surface properties play the most important role in frictional behavior. Friction is a very complex phenomenon, which includes a wide range of mechanical, physical, and chemical processes occurring at various scales simultaneously. Despite the great importance of friction, just a few restricted theories have been proposed till now. The same is valid for computer-aided simulation approaches. This paper presents a multiscale approach for modeling the mechanical behavior of the metallic materials in friction zone under sliding. This approach uses coupled discrete-continuum computational scheme in which a narrow contact zone of interacting bodies is described by the discrete element method and the rest of the material, which experiences elastic deformation, by the conventional finite element method of solid mechanics. Thus, at the mesoscale of friction that corresponds to contacting layers and third body we use computational particle mechanics. Here, special attention is given to describing the mechanical behavior of shape memory alloys that looks very promising for tribological applications of Cu-Al alloys. It is also shown that for obtaining some parameters of the mesomodel it is possible to use molecular dynamics simulation at the atomic scale. Finally, the results of friction simulation are considered and discussed for different values of the model parameters corresponding to the shape memory effect. [ABSTRACT FROM AUTHOR]

Osteoarthritis and osteonecrosis of the femoral head are serious diseases that require surgical treatment (endoprosthetics (EP)). Aseptic loosening of the femoral component of the implant is a consequence of the micro-destruction of bone tissue in the contact area. The mechanical behavior in the zone of contacting materials during EP is determined by the morphology of the surfaces. To study the effect of the roughness of contacting elements, computer modeling was used. A part of the femur with a pin from a superficial endoprosthesis was considered. The mechanical behavior of the model samples was studied under loading similar to the physiological one. Nonlinear features in the mechanical behavior of model samples with different surface roughnesses are revealed. It has been found that the most optimal bone roughness is about 0.2 mm. [ABSTRACT FROM AUTHOR]

Adsorption on activated carbons (AC) is a reliable method for extracting aromatic synthetic organic substances from water. The nature of substituents (acceptor or donor groups) and their number in the benzene ring change the strength of interaction with water molecules and the strength of the π–π interaction between the benzene rings of the molecules of the adsorbate and the basal layer of activated carbons, respectively, determining the selectivity of adsorption of organic substances. The purpose of this work is to determine the effect of substituents in the benzene ring on the efficiency of the adsorption of aromatic compounds on activated carbons. The paper considers the isothermal adsorption of nine monoaromatic compounds of the phenolic and aniline series from an aqueous solution on KAU activated carbon produced by high-temperature activation of fruit pits. The efficiency of selective adsorption was estimated based on the Gibbs adsorption energy and adsorption values in the initial section of the isotherms. The efficiency of adsorption of the studied aromatic substances on KAU activated carbon within equilibrium concentrations close to the conventional conditions of the extraction process is completely determined by the value of ∆Gа and increases in the series of phenol < aniline < o-chlorophenol < o-aminophenol < o-aminobenzoic acid < dinitrophenol < o-nitrophenol < p-nitroaniline. Changes in the adsorption energy are considered taking into account the surface charge and charged particles of structural units of aromatic molecules formed under the effect of solution pH. The adsorbate with two donor groups, o-aminophenol, had no advantages in adsorption energy over adsorbates with acceptor and donor substituents. A linear correlation is revealed between the rise of adsorption energy and the decrease in solubility of aniline and phenol derivatives. The effect of the substituent on the efficiency of the adsorption interaction is thus reduced to a dominant effect on the hydration energy of the aromatic compound. [ABSTRACT FROM AUTHOR]

Sorption on activated carbon (AC) are the most widely used method for deep extraction of synthetic aromatic organic compounds from their aqueous solutions. To achieve maximum efficiency, it is necessary to correctly select the adsorbent by taking into account its structural and sorption characteristics and surface chemistry, as well as the size of molecules of the pollutant and their ability to ionize in a solution at a certain pH value. In this study, the equilibrium adsorption extraction of phenol under static conditions by commercial sorbents with different physicochemical characteristics (Sibunit, KAD, Akant, F300, and KAU) is investigated. Room temperature adsorption isotherms at a dissolved oxygen concentration of 5–6 mg/dm3 and pH = 5.2–7.2 are studied. The effects of the porosity and the nature and number of surface active sites of AC on the efficiency of phenol adsorption from dilute aqueous solutions are studied. It is shown that the small concentrations of surface active sites of the studied commercial sorbents have no substantial effect on the efficiency of purifying aqueous solutions from phenol, but structural and sorption characteristics—in particular, the volume of the narrowest but accessible micropores—have the greatest effect. Among the studied ACs, sorbents Akant, F300, and KAU have such characteristics. [ABSTRACT FROM AUTHOR]

For the first time, analysis of thermal stress distribution arising in a layered ZrB2– SiC – ZrO2 ceramic disk during manufacturing was performed using numerical and analytical methods. The numerical modeling was implemented by the finite-element method considering the temperature dependence of properties of composite components. The residual stress distribution across the layers has a sawtooth character, in which stresses take both negative and positive values. A new analytical solution based on a simplified one-dimensional formulation of the problem for the central part of the disk was proposed. This solution shows that the residual stresses are determined not only by the thermal expansion coefficients and biaxial elastic moduli of the connected materials, but also by a thickness and location of the layers. The results of analytical solution obtained and numerical modeling were in a good agreement. It is shown that, for estimating the residual stress in a laminated composite with assumption that the properties of composite components are temperature-independent, it is appropriate to apply the thermomechanical characteristics corresponding to a high temperature rather than a room or average ones. The porosity effect on the residual stresses in a ceramic laminate was studied. It is found that the consideration of porosity decreased the residual stresses only in the layers where it was entered. Results of the study provide a basis for analyzing residual stresses in the laminates of different compositions and in specific engineering applications. [ABSTRACT FROM AUTHOR]

A new quantification method is proposed for the determination of serum estrone (E1), estradiol (E2), and estriol (E3) based on high-performance liquid chromatography–tandem mass spectrometry combined with differential ion mobility separation (SelexION Technology). This approach allows determining analytes with limits of detection of 4.5, 18 and 45 fg on column for E1, E2, and E3, respectively. The lowest limits of quantification are 0.1, 0.5, and 0.5 pg mL–1 in serum for E1, E2, and E3, respectively. The suitability of proposed method for diagnostic purposes is demonstrated in an analysis of serum from 114 patients of different genders and ages. [ABSTRACT FROM AUTHOR]

Answering a question posed by Vladimir Tkachuk, we prove thatevery connected first countable T1-space is a continuous open image of a connectedmetrizable space. [ABSTRACT FROM AUTHOR]

Hip and knee replacement operations mostly utilize the cementing procedure, which determines the biocompatibility relevance of bone cement, a porous material, which is filled with the body fluid after surgery. The paper proposes a computer model of the bone cement mechanical behavior with explicit and implicit analyses of different-size pores, including isolated macropores. The multilevel simulation utilizes the movable cellular automaton method. The mechanical behavior of test samples, both dry and containing the body fluid, is studied under uniaxial compression and four-point bending. Nonlinear porosity dependences are detected for elastic and strength properties of bone cement during compression tests. [ABSTRACT FROM AUTHOR]

Based on the analytical solution, the paper focuses on the residual stress distribution in disklike composite specimens comprising ceramic layers of different composition during the cooling process after sintering to room temperature. It is shown that varying the layer thickness, it is possible to control the maximum stress distribution. With regard to diffusion zones at the interface between the neighboring layers with different thermal expansion coefficient, it is possible to reduce these dangerous stresses proportionally to the thickness of these zones. Note that for the engineering solution, it advisable to utilize the physical-and-mechanical parameters of composite components for high temperature, rather than for the average temperature. [ABSTRACT FROM AUTHOR]

Key summary points: Aim: The aim of the study is to determine the factors influencing the outcomes of older ventilated medical patients in a large tertiary medical center. Findings: Of 554 older patients (mean age 79 years) who underwent mechanical ventilation for the first time during the study period in-hospital mortality was 64.1% and overall 6-months survival was 26%. A combination of age 85 years and older, poor functional status prior to ventilation, and associated morbidity were the strongest negative predictors of survival after discharge from the hospital. Message: The identification of factors predicting poor survival of mechanical ventilation will assist policy makers in clinical decision-making particularly at times of limited health resources. Background: The development of technologies for the prolongation of life has resulted in an increase in the number of older ventilated patients in internal medicine and chronic care wards. Our study aimed to determine the factors influencing the outcomes of older ventilated medical patients in a large tertiary medical center. Methods: We performed a prospective observational cohort study including all newly ventilated medical patients aged 65 years and older over a period of 18 months. Data were acquired from computerized medical records and from an interview of the medical personnel initiating mechanical ventilation. Results: A total of 554 patients underwent mechanical ventilation for the first time during the study period. The average age was 79 years, and 80% resided at home. Following mechanical ventilation, 8% died in the emergency room, and the majority of patients (351; 63%) were hospitalized in internal medicine wards. In-hospital mortality was 64.1%, with 48% dying during the first week of hospitalization. Overall 6-months survival was 26%. We found that a combination of age 85 years and older, functional status prior to ventilation, and associated morbidity (diabetes with target organ injury and/or oncological solid organ disease) were the strongest negative predictors of survival after discharge from the hospital. Conclusion: Mechanical ventilation at older age is associated with poor survival and it is possible to identify factors predicting survival. In the midst of the COVID-19 pandemic, the findings of this study may help in the decision-making process regarding mechanical ventilation for older people. [ABSTRACT FROM AUTHOR]

In the processes of water purification from organic matter, the biomass of biological activated carbon (BAC) can be used independently (separately from the carrier). In the present work, the enriched culture of microorganisms of biofilm biomass capable of effectively removing xenobiotics from more concentrated water solutions (45 mg/dm3) was obtained using the biofilm washed from the BAC laboratory filter, which has been used for several years for filtering 2-nitrophenol (NP) aqueous solution at a low concentration (8 ± 2 mg/dm3). The procedure of progressive adaptation, including moderate aeration, the stage of endogenous respiration and the elements of anaerobic system, was aimed at obtaining a specialized culture of microorganisms with enhanced survival rate, which would be able to increase the rate of NP destruction with each cycle of adaptation, to provide complete extraction of organic substrates and to prevent the accumulation of excessive concentrations of nitrates. The need of enriched biomass for the treatment of BAC regeneration wastewater arises occasionally. Hence, it is highly important to know the peculiarities of kinetics of biomass transition from the state of "maintenance" into the active state sufficient for effective destruction of the higher levels of xenobiotics, as well as the influence of additional substrates and biomass carriers on these processes. In the present work we have studied the effect of NP concentration, the NP/biomass concentration ratio and the form of biomass on the kinetics of xenobiotic extraction in a batch anaerobic process. Mathematical formulation of experimental data was performed in accordance with the Monod and Haldane/Andrews growth kinetics. During the progressive increase in the initial NP concentration (from 45–50 to 200 mg/dm3) based on the kinetic coefficients of the Haldane–Andrews equation, there was a change in the internal fermentative properties of microbial culture. The increase in specialization of the biomass is represented by a formal decrease in the values of the half-saturation constant Ks and an increase in the concentration inhibition constant Ki indicating the ability of the culture to adapt to assimilation of enhanced xenobiotic concentrations. The enriched native biomass adapted to 200 mg/dm3 of NP was effectively used for utilization of the waste from chemical regeneration of a laboratory BAC filter. Transition to the anoxic mode as the final stage of regeneration activated the groups of microorganisms capable of using nitrates as a terminal electron acceptor. [ABSTRACT FROM AUTHOR]

A biofilm of microorganisms that are characterized by high tolerance and destructive efficiency with respect to the actual level of the initial concentrations of the target substance is formed when filtering xenobiotic-contaminated water through biologically active carbon (BAC). The technological possibilities of prolongation of the effective water processing on BAC are extended using biological and chemical regeneration processes. However, a special recovery procedure is necessary for chemically regenerated water, since the concentrations of target substances in it will be tens to hundreds times higher than their content in water filtered through BAC. The scheme of alkaline regeneration of BAC includes the partial washing-out of the biofilm from the bed in order to preserve the adapted consortium of microorganisms for subsequent culturing on the regenerated sorbent. In a batch apparatus designed to maintain and activate the life of the microflora washed out from the natural biofilm culture, the processes of preservation and acclimatization of microorganisms to a higher xenobiotic concentration are implemented to subsequently use the adapted biomass for recycling regenerated wastewater. The efficiency of the kinetics of destruction of 2-chlorophenol (CP) in the solution volume by microorganisms of the biomass washed out from the biofilm of the working bed of BAC is studied. The rate of destruction of CP by the biomass (X0) washed out from BAC is well described by the Haldane–Andrews kinetics. Sequential increases in the initial concentration of CP (C0) and in the C0 : X0 ratio lead to increases in the amount of specialized microflora in the biomass and in its activity manifested in the growth of the specific rate constant of ChP destruction. The biomass can be easily acclimatized to CP concentrations higher than those achieved in this study (90–100 mg/dm3). The ability of microorganisms to quickly adapt to high concentrations of xenobiotics opens up prospects for the successful use of the suspended biofilm biomass in the recycling of wastewater from chemical regeneration of BAC. [ABSTRACT FROM AUTHOR]

YB proteins are DNA/RNA binding proteins, members of the family of proteins with cold shock domain. Role of YB proteins in the life of cells, tissues, and whole organisms is extremely important. They are involved in transcription regulation, pre-mRNA splicing, mRNA translation and stability, mRNA packaging into mRNPs, including stress granules, DNA repair, and many other cellular events. Many processes, from embryonic development to aging, depend on when and how much of these proteins have been synthesized. Here we discuss regulation of the levels of YB-1 and, in part, of its homologs in the cell. Because the amount of YB-1 is immediately associated with its functioning, understanding the mechanisms of regulation of the protein amount invariably reveals the events where YB-1 is involved. Control over the YB-1 abundance may allow using this gene/protein as a therapeutic target in cancers, where an increased expression of the YBX1 gene often correlates with the disease severity and poor prognosis. [ABSTRACT FROM AUTHOR]

The paper deals with ceramic composites based on the ZrB2 matrix with SiC and MoSi2 particle inclusions. The volume fraction, size, and distribution of both inclusions are varied. The influence of the composite structure on their compressive strength is studied on the proposed computer models of a unit cell using the movable cellular automaton method. As a result, the mechanical behavior of ZrB2–X(SiC)–Y(MoSi2) composites with the different structural arrangements and phase compositions is studied. It is shown that the structure of dual ceramic composites with MoSi2 inclusions, which form mesoscopic granules, demonstrates the highest mechanical properties due to the microcrack retardation as compared to the materials with the uniform arrangement of these inclusions in the composite bulk. [ABSTRACT FROM AUTHOR]

As superconducting quantum circuits scale to larger sizes, the problem of frequency crowding proves a formidable task. Here we present a solution for this problem in fixed-frequency qubit architectures. By systematically adjusting qubit frequencies post-fabrication, we show a nearly tenfold improvement in the precision of setting qubit frequencies. To assess scalability, we identify the types of "frequency collisions" that will impair a transmon qubit and cross-resonance gate architecture. Using statistical modeling, we compute the probability of evading all such conditions, as a function of qubit frequency precision. We find that, without post-fabrication tuning, the probability of finding a workable lattice quickly approaches 0. However, with the demonstrated precisions it is possible to find collision-free lattices with favorable yield. These techniques and models are currently employed in available quantum systems and will be indispensable as systems continue to scale to larger sizes. [ABSTRACT FROM AUTHOR]

The assessment of the vibration strength of elastic metal structures for various purposes is carried out on the basis of mathematical modeling. Proper determining the internal friction coefficient of the metal is of key importance, because this value significantly affects the values of the natural frequencies of damped oscillations and is reflected in the conditions of resonances of various orders. In this article, the internal friction coefficient of the AMg6 aluminum alloy is determined by two methods: electromechanical and laser vibrometry. The dependence of the internal friction coefficient on the fundamental frequency of oscillations in the hertz range is established under the assumption that the isochronous condition is met. The results of this study make it possible to clarify the Voigt hypothesis as applied to the AMg6 alloy in the hertz range. [ABSTRACT FROM AUTHOR]

The efficiency and peculiarities of 2-nitropenol (NP) desorption from activated carbons under the action of biotic and abiotic factors have been studied. The biotic NP desorption during one month reached 25–30% of the initial saturation of sorbent. The rational duration of bioregeneration was found to be equal to 14 days. The rate of biotic desorption is shown to be limited by the rate of internal diffusion. The intensity of self-bioregeneration of biological activated carbon is by an order of magnitude less that the NP destruction rate in the solution volume and to a greater degree corresponds to the intensity of abiotic desorption. [ABSTRACT FROM AUTHOR]

In the autosoliton view, the complete mathematical model of the seismic process taken as the deformation and fracture process of a loaded geomedium combines dynamic equations of solid mechanics and specific constitutive equations for geomedium rheology. These equations describe both the conventional stress-strain evolution due to the stress wave propagation with sound velocities, which are governed by special features of constitutive equations, and slow dynamics of the loaded strong medium. Numerical investigation is given to the generation of deformation autosolitons, front structure, and propagation of intra- and interfault deformation disturbances. Slow deformation disturbances in real geomedium elements are numerically modeled. [ABSTRACT FROM AUTHOR]

Doppler laser interferometry is used to measure the transient time between the slow quasi-stationary stage of damage accumulation in rock samples to the ultrafast catastrophic stage of failure as well as the duration of the autocatalytic stage of macroscopic fracture. Small rock samples are tested for compression and three-point bending, and the velocity of displacement of their lateral surfaces is measured up to macroscopic fracture. The surface velocity at the catastrophic stage proves to be three orders of magnitude higher than the average surface velocity at the quasi-stationary stage of damage accumulation. The transient time to catastrophic failure is estimated at 60–100 ms, and the duration of the ultrafast catastrophic failure stage is 15–20 ms for small marble samples. The transient stage is the process of self-organization of individual acts of fracture into the state of self-organized criticality. At this stage, the distribution of individual acts of fracture evolves into power-law distributions. A simple fracture model with power laws is proposed, which is in full agreement with the experimental data. The developed mathematical model is used to calculate fracture of small rock samples, reproducing uniaxial compression and three-point bending tests, as well as fracture in rock masses with mine openings. We also model the process of faulting and fracturing in the mountains of Central Altai, including the foreshock process, main event (the Chuya earthquake of September 27, 2003) and aftershock process. The calculated seismic process fully corresponds to the Gutenberg–Richter recurrence law, and the calculated aftershock process conforms to the Omori law. [ABSTRACT FROM AUTHOR]

The influence of the fluid saturation of a porous coating on the mechanical properties of the coating and the entire coating-substrate system is addressed. An important practical application is targeted as the wear-resistant coatings of endoprostheses of major human joints. Based on the method of movable cellular automata, a 3D-model of the mechanical behavior of a porous fluid-saturated coating on a titanium substrate is constructed. Using this model, the influence of fluid-saturation of the surface-layer of a ceramic coating on the mechanical characteristics of the coating-substrate system is studied numerically. The simulation results demonstrate that the presence of fluid in a thin surface layer of the coating can strongly affect the mechanical response of the entire coating-substrate system under sufficiently high rates of the local contact loading. In particular, the calculations without taking the fluid into account give overestimated values of strength and hardness of the coated materials under the wetting conditions. A simulation of scratching demonstrates that the material with a fluid-saturated surface layer is more stable to wear. [ABSTRACT FROM AUTHOR]

The nitro and chloro derivatives of phenols are xenobiotics. Active carbon (AC) is often used for the removal of such substances from natural, drinking, and waste waters. To a large extent, the economic feasibility of using AC depends on the method of their regeneration. Upon treating AC with an alkaline solution, the adsorbed phenols are ionized because of their weak acidic properties. The formed phenolate ions are desorbed from the carbon surface because of their lower adsorption energy and AC is regenerated. The study of low-temperature desorption of phenol derivatives is relevant for the development of technology for the regeneration of AC and biologically active carbon (BAC) directly in adsorbers that are made of modern composite (fiberglass) materials that are not designed for operating at temperatures higher than 40–50°C. The low-temperature alkaline desorption of 2-nitrophenol (NP) from equilibrium exhausted AC (reagent : AC ratio 10 : 1) is studied under laboratory static conditions in the mode of single-batch processing. The optimal alkali concentration (0.1 M) providing the maximum degree of sorbent recovery is determined. It is found that the degree of desorption of NP (5.7–45.6%) depends on the equilibrium concentration of sorbent saturation. The lower the equilibrium concentration at which AC exhausts, the lower the efficiency of alkaline regeneration of AC. The efficiency of NP desorption for operating temperatures of 15–35°C is verified. An increase in the temperature of reagent in the studied range does not lead to a substantial increase in the degree of desorption, but reduces the time required to establish the equilibrium of desorption by a factor of 1.5. More than 85–90% of equilibrium 2-nitrophenol desorbed from AC is removed in the first 4 to 8 h of treatment. Compared to microbial treatment, alkaline desorption allows one to achieve higher levels of AC regeneration (by 10–20%) and shorter processing times (100 times faster), which indicates the promising future for inclusion of this operation into bioadsorption technologies. [ABSTRACT FROM AUTHOR]

Sintered yttrium-stabilized zirconia is numerically and experimentally investigated during the Brazilian test. The strain and fracture of homogeneous and inhomogeneous cylindrical specimens under diametral compression are numerically simulated within the framework of mechanics of continuum mechanics. The specimen inhomogeneity is phenomenologically described by random assignment of the strength characteristics in computational cells. Unlike a homogeneous specimen, the strain localization and the formation of numerous fragments at fracture are observed in an inhomogeneous specimen. It is established that the zirconia strain is macroscopically localized. It is shown that sizes of coherently diffracting domains of the tetragonal phase and microdistortion of the lattice after sintering change compared to the initial state and differ for different fragments of a fractured specimen. The internal microstresses on different fragment surfaces change in the range 245–320 MPa depending on the arising strain inhomogeneity. The strain localization correlates with the inhomogeneity of the microstresses arising in the material undergoing deformation. The quantitative and qualitative agreement of the calculated results with the experimental data is observed. [ABSTRACT FROM AUTHOR]

X–Ray therapy is an area of clinical radiology. It has been used with success for treating many non–oncological diseases, as well as malignant neoplasms. However, this type of radiotherapy lacks quality assurance protocols. Quality assurance in radiotherapy is defined as a complex program of compliance with physicotechnical, dosimetric, clinical, personnel, and organizational measures, taking account of the individual features of the patient's body. This applies to all activities in radiotherapy institutions from the moment the patient is admitted to the moment of discharge and subsequent follow–up. From the point of view of physicotechnical support, quality control for X–ray therapy equipment involves a range of characteristics. The aim of the present work was to develop a quality assurance program for X–ray treatment equipment based on these characteristics. Working from the requirements for X–ray treatment equipment presented in various publications, the authors have compiled a list of daily and monthly checks. [ABSTRACT FROM AUTHOR]

The results of determination of mechanical indices of two-layered paperboard by measuring the length of contacts of fibers in the transverse section are presented. The developed technique of getting transverse section of paperboard and evaluations by graphical and computational programs made it possible to determine the total length of contact lines, uniformity of distribution of contact lines by size, and uniformity of their distribution over the area of the transverse section of the paperboard. These parameters characterize the interfiber forces of bonding in the paperboard and, consequently, its mechanical properties. [ABSTRACT FROM AUTHOR]

An experimental investigation of the phenomenon of diffusion of the solution components in nanosized pores is extremely difficult and in certain cases impossible. An effective approach to obtaining qualitative and quantitative estimates of the diffusion process characteristics is computer simulation. Relying on the method of dissipative particle dynamics, a nanoscale numerical model is proposed for estimating the value of diffusion coefficient of the dissolved substance molecules in the pores of different sizes. An aqueous solution of doxorubicin, an antitumor antibiotic, in the pores of hydroxyapatite (a promising carrier medium for solving the problems of targeted administration of highly toxic drugs) is considered as a model system. Using the proposed model, the diffusion coefficient of doxorubicin in the pores of different linear sizes is evaluated at different volume concentrations of the antibiotic. In particular, it is found out that with an increase in the pore size the diffusion coefficient of doxorubicin increases by an order of magnitude and, starting from the pore size of 300 nm, it attains saturation. An increase in the antibiotic concentration from 0.1 to 5% gives rise to a decrease in the diffusion coefficient by more than a factor of 1.5. The developed model can be applied for solving the problems of predicting the release rate of the solution components (including drug molecules) from the pore volume of different solid-phase carrier media. [ABSTRACT FROM AUTHOR]

Peculiarities in the dependences of the elastic and strength properties of ceramics with a hierarchically organized pore structure on the porosity are revealed. To exclude the influence of other microstructural factors, such as, for example, grain size, the study was carried out on the basis of multilevel computer modeling using movable cellular automata and a probabilistic approach. A special computer model of the mechanical behavior of porous ceramics with a bimodal pore size distribution has been developed. At the lower level of the model, small isolated pores are explicitly taken into account and series of calculations are carried out for the representative samples with individual pore arrangement in space. The values of the elastic and strength characteristics of these samples obtained as a result of Weibull analysis serve as effective properties of the porous material matrix at the mesoscale. At the mesoscale, large pores of both equiaxial and elongated shapes are considered explicitly. At the macrolevel, the heterogeneity of the material is described implicitly by setting to the automata the unique elastic and strength properties obtained from the Weibull analysis of the calculation results obtained at the mesoscale. [ABSTRACT FROM AUTHOR]

In the paper, inelastic strain localization in homogeneous specimens and mesovolumes of a polycrystalline material is modeled based on the asymmetric theory of an elastoplastic Cosserat continuum in a two-dimensional formulation for plane strain. It is assumed that rotational deformation in loaded materials occurs due to the development of localized plastic deformation as well as bending and torsion of the material lattice at the micro- and nanoscale levels. For this reason, the parameters of the micropolar model are considered as functions of inelastic strain for each local mesovolume of the continuum. It is shown that the observed parabolic hardening can be attributed to a large extent to the development of rotational deformation modes, bending and torsion, and appearance of couple stresses in the loaded material. The modeling results indicate that if rotational deformation is stopped in the loaded material, its accommodation capacity decreases, the local and macroscopic inelastic strains sharply increase, leading to a much more rapid formation of fracture structures. Conversely, the formation of meso- and nanoscale substructures with high lattice curvature in materials promotes the activation of rotational deformation modes, reduction of localized strains, and relaxation of stress concentrators. [ABSTRACT FROM AUTHOR]

The dynamics of ring current protons with variable boundary conditions in the inner magnetosphere during a magnetic storm has been studied. The spatial and temporal evolution of differential fluxes of protons in the dipole magnetic field has been calculated. The calculations have been performed with the two-dimensional Phenomenological Model of the Ring Current (PheMRC 2-D) offered by the author, which examines the radial and pitch angle diffusions with consideration of losses due to wave–particle interactions. The simulation begins with the distribution of magnetically quiet time. The model has been tested via comparison of the calculated proton fluxes with values measured on the Polar/MICS satellite during the magnetic storm on October 21–22, 1999. The calculated pitch angle distribution is quite consistent (well) with the experimental data. The model has been compared with the other ring current model (Extended Comprehensive Ring Current Model, ECRCM) (Ebihara et al., 2008). PheMRC 2-D is more accurate than ECRCM in describing the experimental data. The offered model can be used to simulate the dynamics of charged particles in the Jovian and Saturn magnetospheres. [ABSTRACT FROM AUTHOR]

Abstract—A numerical study of mechanical properties of zirconium ceramic–cortical bone tissue biocomposite has been fulfilled using a multiple-scale approach. Evolution of mesoscopic stress distribution in the components of biocomposite during its deformation has been studied with the assumption of damage accumulation until the macrostrength criterion is fulfilled. It has been shown that the parameters of the laws of distribution change with damage accumulation. [ABSTRACT FROM AUTHOR]

We consider targeted variation of the relaxation state for polymer components of wood in stages of the life cycle of corrugated cardboard. From the standpoint of the structural physicochemistry of wood, we present a mechanism for the processes occurring in traditional corrugated cardboard production technology. Our thesis is that cellulose and hemicellulose can go from the glassy state to the rubbery (highly elastic) state at 220°C, but under real conditions this transition occurs at room temperature and even at negative temperatures in the case of plasticization by a sufficient amount of water. Transition of lignin from the glassy state to the rubbery state occurs at a temperature above 130°C, and at 70°C-120°C under conditions of sufficient hydration. Formation of strong interfiber bonds is possible only when the polymers forming the contact are in the rubbery or viscous-flow state. [ABSTRACT FROM AUTHOR]

Optical properties of biological coenzyme FAD in an aqueous solution have been studied. Two fluorescence lifetimes, a rotational diffusion time, and an anisotropy parameter have been determined from experiments by recording the decay of polarized fluorescence excited by picosecond laser pulses. The results obtained are discussed and compared with the results of other authors. [ABSTRACT FROM AUTHOR]

Abstract: The decay of polarized fluorescence of tryptophan in water-propylene glycol solution two-photon excited by femtosecond laser pulses was explored. Linearly and circularly polarized light in the wavelength band of 385-510 nm was used for excitation. Processing of the experimental fluorescence signals as functions of time and light polarization provided an opportunity to identify two characteristic lifetimes characterizing the fluorescence intensity decay and the rotational diffusion time τrot. The spectral dependences of the anisotropy parameter Ω and anisotropy parameters r for linearly and circularly polarized excitation have been determined. It is shown that the fluorescence temporal dependence is well described by the sum of two exponents with amplitudes a1 and a2 and characteristic times τf1 and τf2 at all wavelengths in the studied spectral range. The experimental dependences of parameters Ω, r, τf1, and a2/a1 are nontrivial, which indicates the complexity of the excitation relaxation processes. The obtained results can be used for interpretation of the experiments and prove of the theoretical models describing the intensity and polarization of fluorescence of tryptophan molecules in solutions and organic compounds under optical excitation. [ABSTRACT FROM AUTHOR]

Abstract: We have analyzed the decay of fluorescence intensity in indole dissolved in propylene glycol under two-photon excitation by linearly and circularly polarized femtosecond laser pulses in the wavelength range 475-510 nm. The dependences of fluorescence intensity I0, anisotropy r, and parameter Ω on the excitation energy have been determined and analyzed. In particular, a nonmonotonic behavior of I0 indicating the increase of indole excited state density in the excitation energy range above 5.1 eV and the anisotropy sign reversal due to the variation of the symmetry of indole vibronic states have been observed and interpreted theoretically. [ABSTRACT FROM AUTHOR]

A contribution of self-bioregeneration of a sorbent in the course of removing from water of 2-chlorophenol by a stationary bed of biologically activated carbon (BAC) is assessed. The process of regenerating activated carbon is of a sporadic nature; the value, rate and efficiency of spontaneous bioregeneration were established. The total contribution of self-regeneration to the removal of 2-chlorophenol by the BAC bed during the experiment constituted 3.8-6.8%. In a stationary phase of biofiltration the losses of the volume of adsorption pores of activated carbon from vial activities of microorganisms exceed the total effect of the process of spontaneous regenerations. [ABSTRACT FROM AUTHOR]

It is well known that the final stage of macroscopic fracture develops as a catastrophe in a superfast blow-up mode. However, the specific features of this stage are well studied only on large scales of earthquakes. Of particular interest for fracture prediction are both the stage of superfast catastrophic fracture and the mechanical behavior of the medium in the state of self-organized criticality prior to transition of fracture to the blow-up mode in order to reveal precursors of fracture transition to the catastrophic stage. This paper studies experimentally and theoretically the mechanical behavior of the medium prior to the catastrophic stage and transition to the blow-up mode. Rock samples (marble and artificial marble) were tested in three-point bending and uniaxial compression tests. The lateral surface velocities of loaded samples were recorded using a laser Doppler vibrometer. The recording frequency in measurements was 48 kHz, and the determination accuracy of the velocity amplitude was 0.1 μm/s. The estimated duration of the blow-up fracture stage is 10-20 ms. The mechanical behavior of samples in the experimental conditions, including the catastrophic fracture stage, is simulated numerically. The damage accumulation model parameters are determined from a comparison with the experimental data. Certain features of the mechanical response prior to catastrophic fracture are revealed which can be interpreted as fracture precursors. [ABSTRACT FROM AUTHOR]

The aims of the study were to evaluate the effect of media composition on the growth potential and morphology of the in vitro cultured biomass of three cultivars of Hypericum perforatum, and on the production of flavonoids. Agitated shoot cultures were maintained in parallel on Linsmaier and Skoog (LS) and Murashige and Skoog (MS) media supplemented with 0.1-3.0 mg L−1 of α-naphthaleneacetic acid and 6-benzylaminopurine. Methanolic extracts from the biomass collected after 3-wk growth cycles were analyzed quantitatively, for 21 flavonoids using high performance liquid chromatography. Three aglycones (kaempferol, luteolin, and quercetin) and three glycosides of quercetin (hyperoside, quercitrin, and rutoside) were detected in all of the extracts. The total amounts of the estimated compounds increased from 1.18- to 21.66-fold on LS media variants and from 1.52- to 17.34-fold on MS media variants. The main metabolite was quercetin (max. 210.55 mg 100 g−1 dry weight [DW]). The maximum total amounts of all compounds in the biomass of ‘Elixir,’ ‘Helos,’ and ‘Topas’ were 328.53, 255.70, and 166.58 mg 100 g−1 DW, respectively. The shoots of all cultivars cultivated on the LS and MS media containing low levels of plant growth regulators (0.1 mg L−1) accumulated high amounts of flavonoids. The highest amounts were accumulated in shoots of cultivar ‘Elixir’ grown on MS medium. This is the first comparison of flavonoid production in three cultivars of H. perforatum (‘Elixir,’ ‘Helos,’ and ‘Topas’) cultured in vitro, and the first report of flavonoid production in cultivars ‘Elixir’ and ‘Helos.’ [ABSTRACT FROM AUTHOR]

Investigated are changes of the porous structure of biological activated carbon in filtration and after chemical regeneration. It is shown that 71-84 vol % of recovered pores were blocked by the products of microbe vital activity. Alkaline treatment of the bed of biological activated carbon (during several days) makes it possible to prolong efficient nitrophenols removal from water by 10-11 months. [ABSTRACT FROM AUTHOR]

Mechanical properties of thin surface layers and coatings are commonly studied using instrumented indentation and scratch testing, where the mechanical response of the coating - substrate system essentially depends on the substrate material. It is quite difficult to distinguish this dependence and take it into account in the course of full-scale experiments due to a multivariative and nonlinear character of the influence. In this study the process of instrumented indentation of a hardening coating formed on different substrates is investigated numerically by the method of movable cellular automata. As a result of modeling, we identified the features of the substrate material influence on the derived mechanical characteristics of the coating - substrate systems and the processes of their deformation and fracture. [ABSTRACT FROM AUTHOR]