Effect of Spherical Elements of Biosensors and Bioreactors on the Physicochemical Properties of a Peroxidase Protein

External electromagnetic fields are known to be able to concentrate inside the construction elements of biosensors and bioreactors owing to reflection from their surface. This can lead to changes in the structure of biopolymers (such as proteins), incubated inside these elements, thus influencing their functional properties. Our present study concerned the revelation of the effect of spherical elements, commonly employed in biosensors and bioreactors, on the physicochemical properties of proteins with the example of the horseradish peroxidase (HRP) enzyme. In our experiments, a solution of HRP was incubated within a 30 cm-diameter titanium half-sphere, which was used as a model construction element. Atomic force microscopy (AFM) was employed for the single-molecule visualization of the HRP macromolecules, adsorbed from the test solution onto mica substrates in order to find out whether the incubation of the test HRP solution within the half-sphere influenced the HRP aggregation state. Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) was employed in order to reveal whether the incubation of HRP solution within the half-sphere led to any changes in its secondary structure. In parallel, spectrophotometry-based estimation of the HRP enzymatic activity was performed in order to find out if the HRP active site was affected by the electromagnetic field under the conditions of our experiments. We revealed an increased aggregation of HRP after the incubation of its solution within the half-sphere in comparison with the control sample incubated far outside the half-sphere. ATR-FTIR allowed us to reveal alterations in HRP’s secondary structure. Such changes in the protein structure did not affect its active site, as was confirmed by spectrophotometry. The effect of spherical elements on a protein solution should be taken into account in the development of the optimized design of biosensors and bioreactors, intended for performing processes involving proteins in biomedicine and biotechnology, including highly sensitive biosensors intended for the diagnosis of socially significant diseases in humans (including oncology, cardiovascular diseases, etc.) at early stages.

Numerical Analysis of a Flow over Spheres Embedded on a Flat Wall

This paper presents the results of numerical simulations of flow in a periodic channel with the walls covered in the central part by spherical elements that have the same overall surface areas but different radii. Two distributions of the sphere are considered, with the subsequent rows placed one after another or shifted. The computations are performed using the high-order code, whereas the solid elements are modelled with the help of the immersed boundary method. For selected cases, the results are validated by comparison with the solutions obtained using the ANSYS Fluent code on a very dense body-fitted mesh. It was found that the increase in the sphere diameter slows down the flow, which is attributed to the larger blockage of the channel cross-section caused by larger spheres and the occurrence of intense mixing (recirculation) between the spheres. The velocity profiles in the vicinity of the sphere are largely dependent on sphere diameter and rise when it increases. It was found that the distribution of the spheres plays an important role only when the spheres are large. In the part of the channel far from the sphere, the velocity profiles are significantly influenced by the sphere diameter but seem to be independent of the sphere distributions.

Operational lifetime increase of the pumping equipment when pumping-out contaminated groundwater

Purpose. Solving the problem of increasing the pumping equipment operational lifetime when pumping-out contaminated groundwater in the iron-ore industry by extracting the hard, abrasive part, using magnetic filters based on permanent ferrite magnets. Methods. To produce spherical hard-magnetic ferrite elements that catch finely-dispersed magnetic and weakly-magnetic abrasive particles when pumping-out contaminated groundwater in the iron-ore industry, barium ferrite powder BaО∙6Fe2O3 is applied, which is usually used for obtaining hard-magnetic ferrites. Spherical elements for filling a magnetic filtering installation are obtained by the method of spheroidizing the barium ferrite powder in a dragee machine. Sintering of spherical granules obtained from barium ferrite powder is conducted in a high-temperature atmospheric electric box furnace. The sintered spherical elements made of hard-magnetic barium ferrite are magnetized using a magnetic pulsed toroidal-shaped setup in a pulsed constant magnetic field. Findings. For continuous pumping-out and purification of contaminated groundwater from magnetic, weakly-magnetic and non-magnetic highly abrasive particles with the help of magnetic filters, a scheme of a filtering installation of two sections is pro-posed. A technology for producing spherical permanent magnets from barium ferrite powder has been developed for a filtering installation, which includes a coarse purification column with hollow-spherical permanent magnets of 16-17 mm in diameter and a fine purification column with full-bodied spherical barium ferrite magnets of 6-7 mm in diameter. Originality.The term of pumping equipment operation is doubled if to eliminate abrasive wear due to the filtering two-section installation by filling with barium ferrite spherical magnets. In the case of changing the filter, idle time is reduced by using the supplementary auxiliary column. The possibility of processing filtration products and their use in the field of construction and metallurgy without environmental pollution is substantiated. Practical implications. The scheme of magnetic groundwater purification in the iron-ore industry is proposed, consisting of a filtering column of coarse and fine purification from abrasive particles. A technology for producing spherical magnets with different diameters has been developed to ensure the quality of the process. The research results allow to increase the operational lifetime of pumping equipment by eliminating abrasive wear, which will lead to significant savings in the replacement and repair of centrifugal pumps. Keywords: pumping equipment, groundwater, wear, barium ferrite, spherical magnet, filter, iron-ore industry

MODELING THE WORK FLOW OF CUT-OUT SPHERICAL DISKS WITH HYDRAULIC DRIVE FOR FIRE-FIGHTING SOIL-THROWER

In this article, considerable attention is paid to the method of mathematical creation of a structurally complex soil environment with vegetation. Structural and technological parameters of the interaction of the working bodies of the fire-fighting soil thrower with soil have been determined using a simulation-physical-mathematical model of the spherical disk relationship with the soil environment. The disk is equipped with a cutting edge with semicircular cuts. The mathematical model presents complex geometry of all forms of active work planes, as well as the relationship of the working bodies with soil elements. Surfaces of complex construction in the process of applying the finite element method have been transformed into a large number of simplified planar figures. The soil in the simulation physical-mathematical model is described as a complex system of a large number of spherical elements, determinately connecting with each other, as well as with the working planes of the machine. It has been determined that the relationship between the soil particles during deformation is viscoelastic in its nature. The calculation of forces is presented in the form of an algorithm for the interaction of elements on each other in relation to the distance of their location. The equations of motion are used that describe the change in the dynamic state of the soil over time. The movement of the working bodies of the unit, including spherical disk working bodies with cutouts in the framework of the mathematical model, has been considered in the simulated space, described as a parallelepiped. The ability to simulate the interaction of the working bodies of a forest fire soil-throwing machine with a working medium, including plant roots, which are located next to each other in the form of spherical elements in the geometric region. The task of increasing the efficiency of the forest fire-fighting soil-throwing machine when laying fire strips has been solved by improving the quality of preparing the soil shaft with spherical hydraulic disks equipped with a cutting edge with semicircular cuts, which are subsequently taken by thrower-cutters and feed the soil flow in a given direction

A Coupled Discrete–Finite Element Method for the Ice-Induced Vibrations of a Conical Jacket Platform with a GPU-Based Parallel Algorithm

Flowing ice draws special attention due to the dynamic response of jacket platforms. In this study, a coupled discrete element method (DEM) and finite element method (FEM) are developed to analyze the interaction between sea ice and conical jacket platforms to determine the ice-induced vibrations (IIVs) of the structure. To model the ice cover and to investigate ice loads, a DEM with bond-breaking spherical elements is adopted. Meanwhile, the FEM (with a beam element) is applied to model the IIVs of the jacket platform. An efficient transmission scheme between the bond-breaking spherical elements and the beam element is proposed. The graphics processing unit-based parallel algorithm is developed to improve the computational efficiency. The simulated ice loads are verified by comparing them with the full-scale data and different ice load functions. The simulated IIV accelerations of the JZ20-2 MUQ conical platform in the Bohai Sea (China) are consistent with the full-scale data under various ice conditions (e.g., velocity and thickness). The numerical results show that the IIV acceleration increases linearly with the ice velocity and the square of the ice thickness.

Investigation of a boundary simulation of continuity using the discrete solid element method

The discrete solid element method is an efficient numerical method that simulates the large deformation, strong material nonlinearity, fracture, and dynamic problems of continuity. In the discrete solid element method model, the spring stiffness of the spherical elements on the boundary is different from that inside the discrete solid element method model based on the principle of conservation of energy. The spring stiffness of the spherical elements on the boundary of the discrete solid element method model is shown to have a significant effect on the macroscopic properties. According to the position of the spherical elements on the boundary of the discrete solid element method model, the spherical elements on the boundary are divided into three types, which are spherical elements on the surface position, on the edge position, and on the corner position. To accurately reflect the mechanical behavior of the material, the principle of energy conservation is used to strictly deduce the spring stiffness of the three types of spherical elements on the boundary, and the relationship between the spring stiffness and elastic constants is established. The numerical example shows that the calculation accuracy of the discrete solid element method in modeling the mechanical behavior of continuity is improved after the spring stiffness of the spherical elements on the boundary is revised. In addition, the applications of the discrete solid element method to dynamic buckling of the thin plate and buckling of the cracked thin plate are also given.

ТЕХНОЛОГИЧЕСКИЕ ВОЗМОЖНОСТИ ПНЕВМОУДАРНОЙ ШТАМПОВКИ ВЫТЯЖКОЙ ТОНКОЛИСТОВЫХ ДЕТАЛЕЙ

The determination of the deformation parameters for high-speed extraction of axisymmetric thin-film blanks that ensure the shaping of parts without distortion of the shape of the relief and destruction of metal by the method of pneumatic impact punching is performed. On the basis of the conducted researches the technological possibilities of manufacturing of quality axisymmetric thin-walled details by the method of pneumatic impact punching are established. The conditions for the stability of the workpiece when forming the axisymmetric elements of a non-spherical shape are similar to the conditions for the stability of the workpiece during the shaping of spherical elements, and the results can be extended to the drawing of elliptical, shallow conical and other similar parts. Pneumatic impact punching allows you to pull dome-shaped parts without the use of hanging thresholds, two-transversal stamping and other special techniques with a relative billet thickness of two to four times less than allowed when drawing a punch.

COINCIDENCE OF THE TECHNOLOGY AND THE SURFACE TOPOGRAPHY OF SPHERICAL ELEMENTS OCCURING DURING MACHINING PROCESS OF HIGH PRECISION

The paper presents issues concerning the surface layer and the changes in surface topography with respect to spherical elements at the subsequent stages of manufacturing process. Special attention was paid to the forming of surface topography in precision machining processes (preliminary grinding, precision grinding, lapping with polishing). The subjects of research and analysis were spherical elements made of a biomaterial, i.e. titanium alloy (Ti-6.5Al-1.3Si-2Zr). The surfaces of the studied components shaped during the subsequent operations of abrasive machining processes were measured using a coordinate measurement machine (CMM) and a white light interferometer (WLI). Based on the obtained results, the changes in the surface topography of metallic spherical elements brought about during the subsequent operations of precision machining processes were assessed. In addition to this, functional properties of these surfaces were identified.