Fields Of Different Intensities Research Articles

Quantitative estimates of the metachromasia reaction of volutin granules of yeast using neural networks

The metachromatic coloration of volutinous granules of the yeast Saccharomyces cerevisiae is one of the indicators of the influence of sharp geomagnetic field (GMF) perturbations. The metachromasia reaction is based on the aggregation of dye molecules in interaction with inorganic polyphosphates, which are components of volutinous granules. To determine the characteristics of the geomagnetic field that cause the appearance of different colors of the metachromasia reaction, it is necessary to simultaneously monitor this reaction and changes in the GMF. High-quality monitoring is possible with rapid automated counting of cells with all possible color changes during the metachromasia reaction. The aim of the work was to develop a neural network architecture for recognizing and quantifying color changes and heterogeneity in real time during monitoring of the metachromasia reaction of volutinous granules of the yeast S. cerevisiae, which is necessary for further determining their correlations with changes in the geomagnetic field of different intensities. A program based on a nonrecursive labeling algorithm was created to count the number of cells in the study groups. In the course of the work, the software of two neural network architectures was compared to determine the best results in recognizing and quantifying yeast cells with different colors during the volutinous granule metachromasia reaction. It was determined that the Unet architecture type coped with the tasks of cell classification and segmentation much more efficiently than the Inception v3 architecture. The average relative error for automatic recognition of all cell groups was 3.85%, and the maximum relative error was 4.56%. The performance of the neural network was 89.9% when detecting cell segmentation and 86.4% when detecting color differences in the metachromasia reaction.

DEVELOPMENT OF A SETUP FOR VIBRATORY ABRASIVE TREATMENT OF SURFACES OF DECORATIVE ELEMENTS WITH AN ACTIVE WORKING TOOL

This work provides an overview of equipment and technologies for decorative-finishing treatment of parts. It is established that the most effective methods are abrasive mechanical processing techniques such as tumbling, vibrational, centric-rotational, and centric-planetary. Each of them exhibits varying levels of efficiency in specific application areas. Currently, these methods ensure the highest processing efficiency and quality while maintaining the lowest product cost and manufacturing complexity. Technological equipment is currently produced in series, which may include relatively complex assemblies and mechanisms to address complex technological process tasks, each having specific drawbacks. The main directions for improving equipment are identified, and a classifier of part characteristics for vibro-processing is provided to standardize and unify. Structural schemes for setups for vibratory abrasive processing with actively positioned horizontal and vertical working tools are proposed. The uniqueness of these setups lies in the ability to create vibrational fields of different intensities (controlled vibratory exciter of the working chamber) and to control the intensity of the motion of the working tool. Control over these parameters allows adapting the setup to a specific technological process and achieving optimal technical and economic indicators for vibro-processing parts, especially for decorative elements with complex shapes, small dimensions, diverse material characteristics – varying hardness and viscosity, which may pose challenges with conventional methods.

Effects of magnetic field on cd subcellular distribution and chemical speciation in Noccaea caerulescens

Implementing an external magnetic field of suitable strength has been reported to increase Cd uptake by Noccaea caerulescence. However, only a few mechanisms promoting this efficiency have been reported. A series of culture experiments was conducted to explore how Cd subcellular distribution and speciation vary within the tissue of N. caerulescens when subjected to external magnetic fields of different intensities. Without a magnetic field, over 80% of the Cd was deposited in the cell wall and cytoplasm, indicating that cell wall retention and cytoplasm isolation are significant mechanisms for the detoxification of Cd. An external magnetic field (120 mT) increased the Cd concentrations deposited in the cytoplasm and water-soluble inorganic Cd in the roots, increasing the cell wall-bound Cd and undissolved Cd phosphate in the shoots. Meanwhile, the magnetic field increased carbonic anhydrase activity in plant shoots, except at 400 mT. These results indicated that an external field can elevate the Cd decontamination capacity of N. caerulescens by changing the subcellular compartmentalization and speciation of Cd in different tissues.

Enhanced fluidization of solid particles in an oscillating acoustic field

Compared with an ordinary fluidized bed, the fluidization quality of solid particles can be effectively improved by vibration induced by appropriate acoustic fields. The effects of sound on the hydrodynamic behavior of fluidized bed have been investigated under the application of acoustic fields of different intensities (110–130 dB) and frequencies (50–500 Hz). The obtained results show that the perturbation effect of the sound field on fixed-bed pressure drop becomes more significant with increasing sound pressure level, exerting a larger pressure than present under ordinary conditions, due to the change in particle arrangement induced by the acoustic field. Except for a particular frequency, the minimum fluidization velocity in the bed decreases gradually with the increase in the ratio of bed height to bed diameter. The rising velocity of the bubble and the average overflow velocity of residual gas in collapse tests are reduced by the acoustic field.

Modeling and optimisation of magnetic field assisted electrochemical spark drilling using hybrid technique

ABSTRACT The present paper focuses on the application of a hybrid methodology for multi-objective optimisation (MOO) of an in-house deigned and fabricated magnetic field-assisted electrochemical spark drilling (MF-ECSD) process where an electromagnetic unit is added in the setup to create magnetic field of different intensities. The process combines Taguchi methodology (TM) with response surface methodology (RSM) for modelling and grey relational analysis (GRA) with principal component analysis (PCA) methodology for MOO. TM is utilised as the core values in RSM to create the second-order response model, and it is used to find the optimum level of input parameters, namely, voltage (V), electrolyte concentration (EC), tool rotational speed (TRS) and magnetic field intensity (MFI). Material removal rate (MRR), machining depth (MD) and overcut (OC) are the responses. PCA is used to calculate the weight associated with each quality feature.

Numerical renormalization group study of the Loschmidt echo in Kondo systems

We study the dynamical properties of the one-channel and two-channel spin-1/2 Kondo models after quenching in Hamiltonian variables. Eigen spectrum of the initial and final Hamiltonians is calculated by using the numerical renormalization group method implemented within the matrix product states formalism. We consider multiple quench protocols in the considered Kondo systems, also in the presence of external magnetic field of different intensities. The main emphasis is put on the analysis of the behavior of the Loschmidt echo L(t), which measures the ability of the system’s revival to its initial state after a quench. We show that the decay of the Loschmidt echo strongly depends on the type of quench and the ground state of the system. For the one-channel Kondo model, we show that L(t) decays as, L(t)sim (tcdot T_K)^{-1.4}, where T_K is the Kondo temperature, while for the two-channel Kondo model, we demonstrate that the decay is slower and given by L(t)sim (tcdot T_K)^{-0.7}. In addition, we also determine the dynamical behavior of the impurity’s magnetization, which sheds light on identification of the relevant time scales in the system’s dynamics.

Hydrodynamics and Warmth Trade in Cycles of Cooling of an Attractive Plate in an Attractive Fluid in the Attractive Field

The effect of the magnetic field on heat transfer processes of a magnetized steel plate cooled in a magnetic fluid is experimentally studied. Thermocouples were installed at six points on the surface of the plate along its length. The plots of temperature versus time are obtained in the absence of a magnetic field and in magnetic fields of different intensity. It is found that the intensity of heat exchange depends to a large extent on the magnitude of the magnetic field and on the location of points on the surface of the plate. In a magnetic field, cooling of the central part of the plate occurs with the same intensity as in the absence of a magnetic field and with a lower intensity in comparison with other points on the surface of the plate. Near the plate ends, the cooling rate of the surface is much greater in the magnetic field than in the absence of it. With increasing magnetic field strength, the cooling rate of points in the central part of the plate decreases and is less than in the absence of a magnetic field. The dependence of heat transfer on the magnitude of the magnetic field is explained by the distribution of the magnetic forces acting on the liquid surrounding the plate and the nature of the vapor-air cavities formed near its surface. Experiments on simulation of formation and the shape of vapor-air cavities in a liquid surrounding a magnetizing plate are described.

INCREASING OF WEAR RESISTANCE OF LINEAR BLOCK-POLYURETHANES BY THERMAL PROCESSING METHODS

A significant imperfection of parts made from linear block-polyurethanes under conditions of friction contact in the presence of water medium is an intensification of hydrolysis processes and reduction of bulk strength. In order to slow down the hydrolysis process, samples of the polyurethanes were subjected to three types of thermal impacts: thermal processing during some time, infrared and laser irradiations. It has been established that processing in thermal fields of different intensity allows 5-10 times increase of wear resistance of these materials during friction in water medium.

Electric Charge-Induced Active Control of Nucleate and Rapid Film Boiling at the Nanoscale: a Molecular Perspective

An effort has been made to understand the nucleate and the rapid film boiling phenomena under the influence of an electric field using a molecular viewpoint. The behavior of water molecules with a solid copper surface during the film boiling process in the presence of an electric field of different intensities has been studied. The molecular reasoning behind the suppression of the Leidenfrost phenomenon upon application of a uniform electric field along the heating substrate is established. Furthermore, the effect of surface characteristics with different wettabilities on film boiling in the presence of an electric field has also been studied. The electric field produces a finger-like water column besides thinning of the water film over a non-wetting surface. A similar phenomenon is also evident over a hydrophilic surface only after reaching a threshold value of electric charge intensity. Molecular simulations have explained the phenomenon of nucleate boiling of water on hydrophilic or non-wetting surfaces. Finally, the ability to control the bubble formation and suppression at a required location using an electric field has also been demonstrated. The water molecules near the surface experience dispersion at a lower electric field and an attraction force at a higher electric field, mimicking bubble nucleation and suppression, respectively.

Effects Induced by a Weak Static Magnetic Field of Different Intensities on HT-1080 Fibrosarcoma Cells.

In this study, we investigated the effects of weak static magnetic fields (SMFs) on HT-1080 human fibrosarcoma cells. Exposures to SMFs for four consecutive days were varied from 0.5to 600 µT for treated units, while exposures to control units were held at 45 µT. Growth rates were measured by comparing cell counts, whereas membrane potentials, mitochondrial calcium, mitochondrial superoxide (O2 - ), nitric oxide (NO), hydrogen peroxide (H2 O2 ), intercellular pH, and oxidative stress were measured by using fluorescent dyes. The relative cell growth rates vary with the angle of the SMFs. Increases in the magnitude of the SMFs increased concentrations of mitochondrial calcium and membrane potential and decreased intracellular pH. H2 O2 , an important reactive oxygen species (ROS), increases at 100and 200 µT, decreases at 300and 400 µT and increases again at 500and 600 µT. Overall, oxidative stress increases slightly with increasing SMFs, while superoxide and NO concentrations decrease. These results indicate that weak SMFs can accelerate and inhibit cell growth rates and induce alterations in ROS. Changes in ROS and oxidative stress are important for various cell functions. Calcium influx into mitochondria was one of the initial steps into the corresponding changes. Bioelectromagnetics. 2021. © 2021 Bioelectromagnetics Society.

Refractive-index-matched coupling generated by magnetic fluid around cladding removed multimode optical fiber

Abstract For the cladding removed multimode fiber, when the refractive index of the external solution is close to the fiber core, it will cause refractive-index-matched coupling effect. In this work, the appearance of two index-matched points was observed. One of the index-matched point located at short wavelength, which had not been reported previously. Then, magnetic fluid was used as the external solution around the fiber core. As magnetic fields of different intensities were applied, the refractive-index-matched coupling effect occurred, which was different from that happening within isotropic solution. The observed phenomenon was mainly due to the anisotropy of the magnetic fluid under magnetic field. Based on the establishment of theoretical model and formulation of empirical equation, numerical simulations were also employed to further investigate the refractive-index-matched coupling within the anisotropic solution.

The Effect of Temperature on the Viscosity of Cobalt Ferrite Nanofluids

The temperature dependence of viscosity is an essential property of the magnetic fluids applied for heat transfer systems. This property was considered in our work for Cobalt ferrite nanofluids - one of the most explored magnetic materials recently by their improved magnetic characteristics. Cobalt ferrite nanoparticles (CFNPs) were prepared by the co-precipitation method. The characterization of the synthesized particles was analyzed by various techniques such as X-ray diffraction, transmission electron microscopy, vibrating sample magnetometry, and thermal gravimetric analysis. The effect of temperature on the viscosity of Cobalt ferrite nanofluids was investigated. Experiments were carried out in the range of particle concentration from 0.5 to 7 % without and with a magnetic field application. The dynamic viscosities of these nanofluids were measured as the shear rate and temperature dependence under the magnetic field of different intensities, using a standard rotating rheometer. The cobalt ferrite fluids exhibit a yield shear-thinning behavior at all the temperatures from 25 to 55 oC. The experimental results show that the viscosity decreases when the temperature is increased. This variation is exponentially and dependent on the shear rate. The temperature-dependent viscosity is not influenced significantly by either particle concentration or magnetic field. From the obtained results, the Arrhenius equation for the viscosity-temperature relationship is applied.

Critical current performance of Bi-2223 HTS tape in temperature range above liquid nitrogen vaporization temperature

<p indent=0mm>(Bi, Pb)₂Sr₂Ca₂Cu₃O₁₀ (Bi-2223) high temperature superconducting (HTS) tape is one of the high temperature superconducting wires for commercial applications recently. Its superconducting critical transition temperature is <sc>105–110 K,</sc> which is higher than that of another commercially coated HTS REBa₂Cu₃O₇ conductor tape <sc>(90–93 K).</sc> The Bi-2223 tape has a wide range of superconducting temperatures above the vaporization temperature of liquid nitrogen <sc>(77 K).</sc> The critical currents of two Bi-2223 tape specimens were systematically calculated, and the findings evaluated to understand the superconductive current-carrying characteristics of Bi-2223 tape in the temperature range above <sc>77 K.</sc> To research their effects on the critical current of the specimens in this temperature range, we applied magnetic fields of different intensities and angles to the specimens. The results of the measurement are recorded in this paper in the temperature range of <sc>77–92 K,</sc> the magnetic field strength range of <sc>0–0.2 T</sc> and the magnetic field angle range of 0°–90°. The results show that the Bi-2223 tape can still bear the practical significance of the superconducting current at <sc>92 K.</sc> If there is no external magnetic field, or the external magnetic field is almost parallel to the HTS tape surface and weaker than <sc>0.1 T,</sc> the critical current in the self-field can still sustain 40%–50% of its critical current at <sc>77 K.</sc> For example, the results of this study have a significant reference price for its use in this temperature range, providing basic information for the creation of cable applications that are superconductive.

Effects of Pulsed Magnetic Fields of Different Intensities on Dislocation Density, Residual Stress, and Hardness of Cr4Mo4V Steel

To study the effects of pulsed magnetic fields of different intensities on the dislocation density, residual stress, and hardness of Cr4Mo4V steel, magnetic treatment is conducted at 0, 1.0, 1.3, 1.5, 2.0, and 2.5 T. The dislocation density and residual stress are measured using Electron Backscatter Diffraction (EBSD) and X-ray technique, respectively. The results reveal the dislocation density and compressive residual stress decrease at lower magnetic fields such as 1.0 T and 1.3 T, while they increase at higher magnetic fields such as 2.0 T and 2.5 T. The average value of kernel averaged misorientation (KAM) and compressive residual stress decrease about 10.4% and 15.8%, respectively, at 1.0 T, while they increase about 5.88% and 18.2%, respectively, at 2.5 T. The average value of hardness decreases about 3.5% at 1.0 T, from 817 HV to 787 HV. With the increments of intensities, the hardness of the treated samples increases. The hardness essentially remains unchanged at 2.0 T and 2.5 T. The reason for the dislocation motion under the action of pulsed magnetic fields is discussed.

Assessment of dynamic characteristics of thin cylindrical sandwich panels with magnetorheological core

Based on the equivalent single-layer linear theory for laminated shells, free and forced vibrations of thin cylindrical sandwich panels with magnetorheological core are studied. Five variants of available magnetorheological elastomers differing in their composition and physical properties are considered for smart viscoelastic core. Coupled differential equations in terms of displacements based on the generalized kinematic hypotheses of Timoshenko accounting for transverse shears with coefficients depending on the complex shear modulus for a smart core are used to govern vibrations of cylindrical panels. Assuming conditions of simple support for straight and curvilinear edges, solutions in the explicit form describing natural modes as well as an equation with respect to the required complex eigenfrequencies are found. To predict the shell response to an external harmonic force, the general solution of non-homogeneous governing equations is derived in the form of series in natural modes. To estimate damping capability of magnetorheological elastomers under consideration, the principle tunable parameters, the lowest natural frequencies and associated logarithmic decrements are calculated for the same panels with different magnetorheological elastomers under the action of a magnetic field of different intensities. Finally, the amplitude–frequency plots for magnetorheological elastomer-based panels of different opening angles with and without magnetic field are presented.

Research of the stress-strain state of cylindrical elements of engineering constructions of special purpose under the effect of temperature load

Active development of monolithic-frame construction in the recent period of time requires a new approach to the calculation of elements of building structures. Concrete columns are one of the most important elements of such buildings, the failure of which is of great durability. Loss of strength characteristics of the column may occur as a result of the loads caused by the effect of temperature fields. Therefore, research related to the influence of temperature on the supporting elements of structures of military objects, is relevant and of great importance.The non-stationary temperature field in a cylindrical concrete column, which changes over time under high temperatures, is investigated. When modeling the heating process of a column, the boundary conditions of the third kind are taken into account. Using the Laplace transform, we obtained analytical expressions for the research of a temperature field. The stress-strain state of the column with pinched and free ends is determined, which is caused by a non-stationary temperature field, where various values of the heat transfer coefficient between column and the environment were taken into account.One of the most significant causes of increased danger for such structures is uneven heating and changes in the characteristics of strength and deformability of concrete during and after the fire. At the same time it is necessary to solve the issues connected with ensuring sustainable and reliable operation of building structures, including the influence of high temperatures, due to the adoption of appropriate materials or protective coatings. Thus, mathematical modeling of the processes of temperature fields in a stress-strain state of cylindrical structures can significantly increase accuracy of calculations, which contributes to the strength and reliability of engineering structures. The graphic dependences of radial, ring, and axial stresses from the radius are researched as a result of the temperature fields of different intensity on the rod elements are obtained and we have found radial displacement at different temperature.

Investigation of the magnetic field effect upon interpolymeric complexes formation based on bovine serum albumin and poly(aspartic acid)

The study presents a novel strategy for obtaining highly ordered interpolymeric complexes based on a protein, bovine serum albumin and a synthetic polymer, poly(aspartic acid). In this approach, experimental tests were carried out in the presence of a magnetic field of different intensities, namely 0.11 T and 0.3 T produced by permanent magnets. The influence of the magnetic force on the complexation process and the resulted self-assembled structures were studied by means of FTIR spectroscopy, X-ray diffraction, DLS, SEM microscopy and in vitro assay. The changes in the FTIR spectra acquired after 24 h of exposure were connected with conformational changes in the secondary structure and increased interactions between polymers, particularly when a higher intensity field was used. Due to a large anisotropy of magnetic susceptibility characteristic to both proteins and polypeptides, the magnetic field generated ordered assemblies consisting in globular structures of nanometric dimensions. This assembly strategy using magnets, along with remote manipulation capability can provide a versatile, contact-free, and inexpensive tool to create new, complex materials with tailorable characteristics.

Green and sustainable methanol production from CO2 over magnetized Fe[sbnd]Cu/core–shell and infiltrate mesoporous silica-aluminosilicates

In this present work, green and efficient utilization concepts in the form of the use of an external magnetic field have been applied to improve catalytic performance in CO2 hydrogenation. The 10Fe10Cu catalysts with two types of supports, core–shell and infiltrate mesoporous silica-aluminosilicate materials, were applied under external magnetic fields of different intensities (0, 20.8 mT, 27.7 mT) and orientations (north-to-south (N–S), south-to-north (S–N) directions). It was found that a magnetic field considerably enhanced both CO2 conversion and methanol and DME selectivities. The highest CO2 conversion was obtained over 10Fe10Cu/infiltrate catalyst under the magnetic field conditions of 27.7 mT and 4N–S direction at 260 °C (conversion was 1.5 times greater than that without a magnetic field). Under such conditions and at 240 °C, the highest methanol and DME space time yields were obtained, with results 1.8–1.9 times higher than those of without a magnetic field. These excellent performances could be ascribed to the superior adsorption of CO2 and H2 reactant gas molecules over the surface of magnetized catalysts under external magnetic field. This leads to the advantages of the catalyzed CO2 hydrogenation–decreases in the operating temperature and simultaneous reduction in CO2 emission to the atmosphere. This therefore facilitates a carbon-neutral route of CO2 utilization.

Impact of Static Magnetic Field on the Antioxidant Defence System of Mice Fibroblasts.

Results of research assessing the biological impact of static magnetic fields are controversial. So far, they have not provided a clear answer to their influence on cell functioning. Since the use of permanent magnets both in everyday life and in industry becomes more and more widespread, the investigations are continued in order to explain these controversies and to evaluate positive applications. The goal of current work was to assess the impact of static magnetic field of different intensities on redox homeostasis in cultures of fibroblasts. The use of permanent magnets allowed avoiding the thermal effects which are present in electromagnets. During the research we used 6 chambers, designed exclusively by us, with different values of field flux density (varying from 0.1 to 0.7 T). We have noted the decrease in the activity of superoxide dismutase (SOD) and glutathione peroxidase (GPx). The static magnetic fields did not modify the energy state of fibroblasts— adenosine triphosphate (ATP) concentration was stable, as well as the generation of malondialdehyde (MDA)—which is a marker of oxidative stress. Results of research suggest that static magnetic fields generated by permanent magnets do not cause oxidative stress in investigated fibroblasts and that they may show slight antioxidizing activity.

IMPACT OF ULTRASOUND ON COAL DESULFURIZATION AND PROCESS OF BIOLEACHING OF METALS

This paper briefly reviews a range of modern research and methodological literature that explores the impact of ultrasound on solid substrates, water systems and microorganisms. The authors examined various physical-chemical and biological effects occurring in particular in microorganisms as well as in processes, in which they are involved, under the exposure to ultrasound fields of different intensity and frequency. The examples of the use of ultrasound treatment aimed at increasing technological results of coal desulfurization as well as bioleaching of metals are provided.