Basis Of Experimental Research Research Articles

CLINICAL-EXPERIMENTAL JUSTIFICATION OF PATHOGENETIC TREATMENT OF DIABETIC DAMAGE OF THE PERIPHERAL NERVOUS SYSTEM

Background. Diabetes mellitus is a chronic endocrinological disease that, in addition to the somatic sphere, affects all departments and levels of the nervous system. At the same time, its prevalence is increasing every year. Most often, neurological manifestations concern the peripheral nervous system in the form of sensory-motor polyneuropathies. Aim: To clinically and experimentally study the effectiveness of the complex scheme of prevention and treatment of diabetic polyneuropathy, which is composed taking into account the pathogenetic mechanisms of the studied pathology. To find out the clinical features of the course of the disease and electrophysiological patterns. Under experimental conditions, to study the dynamics of changes in the indicators of sensitivity (nociception) and motor function of peripheral nerves in case of diabetic nerve damage. Materials and methods. In the work, streptozotocin-induced diabetic polyneuropathy was reproduced in rats in a chronic experiment. The formation of the latter was confirmed by a morphological study of the sciatic and tail nerves with the determination of edema and degeneration of Schwann cells, as well as segmental demyelination and spasm of precapillary arterioles. Nicergoline, alpha-lipoic acid, group B vitamins, NG-nitro-L-arginine were used for therapeutic or preventive purposes in groups of animals. The speed of conduction of excitation along the tail nerve was studied. In addition, the "hot plate" test was used. In the clinical part of the work, 43 patients with diabetic polyneuropathy were examined. In addition to the clinical and neurological examination; assessed the severity of polyneuropathies according to the scale of neuropathy symptoms, as well as stimulation electroneuromyography.The patients were divided into groups: the first received a developed treatment complex, the second received conventional treatment. Results. The obtained data indicate the feasibility of using direct (NG-nitro-L-arginine) and indirect (nicergoline - "Sermion" and LC - "Alpha-lipon") inhibitors of nitric oxide synthesis, as well as the complex of vitamin preparations "Neovitam", taking into account their reparative and antioxidant properties, in the clinic in patients with diabetic polyneuropathy with a therapeutic, and possibly preventive purpose. The positive experimental and clinical effects of the developed DPP prevention and treatment scheme are associated with the development of antioxidant and reparative effects, as well as the restoration of the myelin sheath of peripheral nerves, since demyelination contributes to the development of the clinic of polyneuropathy. Conclusion. Patients with diabetic polyneuropathy who received a complex treatment scheme achieved probable clinical, neurological and neurophysiological improvement. On the basis of experimental research, the probable mechanisms of this kind of improvement due to the restoration of myelin, blood circulation, antioxidant and reparative effects have been proven.

A Systematic Review of Dust Suppression Methods by Experiment Based on Intelligent Technology in the Coal Mines

The mining and its transportation processes generate a substantial quantity of dust, which harms miners' health. The extended inhalation of dust particles could result in pneumoconiosis. There are numerous studies on coal mine dust removal, but only a handful of articles critically comment on it. A systematic coal mine dedusting literature review has been conducted to attempt a comprehensive and reproducible analysis. This article reviews dust suppression methods by experiment in coal mines from three aspects: chemical modification of dust removers, structural improvement of dust removers, and other factors. The review showed that independent experimental research suits dust remover's structural improvement and chemical modification. Compared to non-phytochemical modifications, phytochemical modifications are more efficient and environmentally friendly. The development of dust remover structures concentrates primarily on the nozzle structure, nozzle diameter, the number of holes, and the distance, with the nozzle diameter being of particular significance. Sometimes, tweaking the nozzle structure does not yield significant efficiency improvements. However, supersonic nozzles demonstrate high efficiency and are likely to be a key area of future research. Experiments also investigated other factors' effects on coal mines' dust removal efficacy, including ventilation system, metamorphic degree of coal, and particle diameter. This review provides the latest dust removal technology information for coal mines. Intelligent technology provides the basis for experimental research on dust removal in coal mines. The future trends of experimental research in the coal mine dust control field include intelligent and automated dust control systems, comprehensive control of multiple pollutants, application of new materials and technologies, and interdisciplinary collaboration and cross-disciplinary research.

Sterile soil mitigates the intergenerational loss of gut microbial diversity and anxiety-like behavior induced by antibiotics in mice

The decline in gut microbial diversity in modern humans is closely associated with the rising prevalence of various diseases. It is imperative to investigate the underlying causes of gut microbial loss and restoring methods. Although the impact of non-perinatal antibiotic use on gut microbiota has been recognized, its intergenerational effects remain unexplored. Our previous research has highlighted soil in the farm environment as a key factor for gut microbiome health by restoring gut microbial diversity and balance. In this study, we investigated the intergenerational consequences of antibiotic exposure and the therapeutic potential of sterile soil. We treated C57BL/6 mice with vancomycin and streptomycin for 2 weeks continuously, followed by a 4–8 week withdrawal period before breeding. The process was repeated across 3 generations. Half of the mice in each generation received an oral sterile soil intervention. We assessed gut microbial diversity, anxiety behavior, microglial reactivity, and gut barrier integrity across generations. Antibiotic exposure led to a decrease in gut microbial diversity over generations, along with aggravated anxiety behavior, microgliosis, and altered intestinal tight junction protein expression. Oral sterile soil intervention restored gut microbial diversity in adult mice across generations, concomitantly rescuing abnormalities in behavior, microgliosis, and intestinal barrier integrity. In conclusion, this study simulated an important process of the progressive loss of gut microbiota diversity in modern humans and demonstrated the potential of sterile soil to reverse this process. This study provides a theoretical and experimental basis for research and interventions targeting multiple modern chronic diseases related to intestinal microorganisms.

Analysis of Shear Model for Steel-Fiber-Reinforced High-Strength Concrete Corbels with Welded-Anchorage Longitudinal Reinforcement.

According to the shear capacity test results of six steel-fiber-reinforced high-strength concrete (SFHSC) corbels with welded-anchorage longitudinal reinforcement under concentrated load, the effects of shear span ratio and steel fiber volume fraction on the failure mode, cracking load and ultimate load of corbel specimens were analyzed. On the basis of experimental research, the shear transfer mechanism of corbel structure was discussed. Then, a modified softened strut-and-tie model (MSSTM), composed of the diagonal and horizontal mechanisms, was proposed, for steel-fiber-reinforced high-strength concrete corbels. The contributions of concrete, steel fiber and horizontal stirrups to the shear bearing capacity of the corbels were clarified. A calculation method for the shear bearing capacity of steel-fiber-reinforced high-strength concrete corbels was established and was simplified on this basis. The calculation results of the model were compared with the test values and calculation results of the GB50010-2010 code, the ACI318-19 code, the EN 1992-1-1 code and the CSA A23.3-19 code. The results showed that the concrete corbel with small shear span ratio mainly has two typical failure modes: shear failure and diagonal compression failure. With the increase in shear span ratio, the shear capacity of corbels decreases. Steel fiber can improve the ductility of a reinforced concrete corbel, but has little effect on the failure mode of the diagonal section. The calculated values of the national codes were lower than the experimental values, and the results were conservative. The theoretical calculation values of the shear capacity calculation model of the corbels were close to the experimental results. In addition, the model has a clear mechanical concept considering the tensile properties of steel-fiber-reinforced high-strength concrete and the influence of horizontal stirrups, which can reasonably reflect the shear transfer mechanism of corbels.

Hair Growth Effect of DN106212 in C57BL/6 Mouse and Its Network Pharmacological Mechanism of Action.

Centipeda minima (CMX) has been widely investigated using network pharmacology and clinical studies for its effects on hair growth via the JAK/STAT signaling pathway. Human hair follicle papilla cells exhibit hair regrowth through the expression of Wnt signaling-related proteins. However, the mechanism of action of CMX in animals has not been elucidated fully. This study examined the effect of induced hair loss and its side-effects on the skin, and observed the mechanism of action of an alcoholic extract of CMX (DN106212) on C57BL/6 mice. Our results showed that DN106212 was more effective in promoting hair growth than dimethyl sulfoxide in the negative control and tofacitinib (TF) in the positive control when mice were treated with DN106212 for 16 days. We confirmed that DN106212 promotes the formation of mature hair follicles through hematoxylin and eosin staining. We also found that the expression of vascular endothelial growth factor (Vegfa), insulin-like growth factor 1 (Igf1), and transforming growth factor beta 1 (Tgfb1) is related to hair growth using PCR. DN106212-treated mice had significantly higher expression of Vegfa and Igf1 than TF-treated ones, and inhibiting the expression of Tgfb1 had similar effects as TF treatment. In conclusion, we propose that DN106212 increases the expression of hair growth factors, promotes the development of hair follicles, and promotes hair growth. Although additional experiments are needed, DN106212 may serve as an experimental basis for research on natural hair growth-promoting agents.

Reuse of waste rubber in pervious concrete: Experiment and DEM simulation

The reuse of waste rubber has a profound impact on environmental protection and resource recycling. To evaluate the feasibility of adding waste rubber into pervious concrete, the effects of rubber content and particle size on the mechanical properties of pervious concrete are investigated through experiments and discrete element method (DEM) simulation. The compressive failure mode of pervious concrete gradually transits from tensile failure to shear failure with the increase of rubber content, showing a decrease in compressive strength, and the larger the particle size is, the stronger the attenuation effect on the strength is. Rubber particles play a role in isolating coarse aggregates from the cement matrix and form a weak bond with the matrix, showing a weak bridging effect in stress transmission at the left and right ends of the crack, so that the splitting tensile strength of pervious concrete significantly decreases with the increase of rubber content, and the weakening effect of coarse rubber on the splitting tensile strength is stronger than that of fine rubber. Due to the low strength of rubber itself and weak bonding with cement matrix, pervious concrete with high rubber content breaks in advance at the bottom of the midspan, resulting in the decline of flexural capacity, and it decreases more obviously with the increase of rubber size. Although the direct tensile strength of pervious concrete gradually decreases with the increase of rubber content, the addition of rubber improves the plasticity of pervious concrete. Moreover, the plastic reinforcement effect of pervious concrete is the strongest when the rubber content reaches approximately 10%, and this toughening effect increases with the decrease of rubber size. On the basis of experimental research, a universal DEM model considering rubber content and particle size is established, which can well predict the mechanical performance of rubberized pervious concrete in terms of strength, failure mode, elastic modulus and ultimate strain.

A novel mechanism of cannabidiol in suppressing ovarian cancer through LAIR-1 mediated mitochondrial dysfunction and apoptosis.

Cannabidiol (CBD) is a nonpsychoactive cannabinoid compound. It has been shown that CBD can inhibit the proliferation of ovarian cancer cells, but the underlying specific mechanism is unclear. We previously presented the first evidence for the expression of leukocyte-associated immunoglobulin-like receptor 1 (LAIR-1), a member of the immunosuppressive receptor family, in ovarian cancer cells. In the present study, we investigated the mechanism by which CBD inhibits the growth of SKOV3 and CAOV3 ovarian cancer cells, and we sought to understand the concurrent role of LAIR-1. In addition to inducing ovarian cancer cell cycle arrest and promoting cell apoptosis, CBD treatment significantly affected the expression of LAIR-1 and inhibited the PI3K/AKT/mTOR signaling axis and mitochondrial respiration in ovarian cancer cells. These changes were accompanied by an increase in ROS, loss of mitochondrial membrane potential, and suppression of mitochondrial respiration and aerobic glycolysis, thereby inducing abnormal or disturbed metabolism and reducing ATP production. A combined treatment with N-acetyl-l-cysteine and CBD indicated that a reduction in ROS production would restore PI3K/AKT/mTOR pathway signaling and ovarian cancer cell proliferation. We subsequently confirmed that the inhibitory effect of CBD on the PI3K/AKT/mTOR signal axis and mitochondrial bioenergy metabolism was attenuated by knockdown of LAIR-1. Our animal studies further support the in vivo anti-tumor activity of CBD and suggest its mechanism of action. In summary, the present findings confirm that CBD inhibits ovarian cancer cell growth by disrupting the LAIR-1-mediated interference with mitochondrial bioenergy metabolism and the PI3K/AKT/mTOR pathway. These results provide a new experimental basis for research into ovarian cancer treatment based on targeting LAIR-1 with CBD.

Reinforcement performance of prestressed unbonded carbon fiber reinforced polymer (CFRP) in continuous beam under artificial intelligence technology

Due to the influence of various factors such as design, construction and use, concrete structures are prone to various damages and defects, so it is necessary to strengthen and repair, and the strengthening technology of carbon fiber external bonding plate is one of the important methods. Therefore, a study on the strengthening performance of prestressed unbonded carbon fiber reinforcement of continuous beams under artificial intelligence technology is proposed. Concrete beams were tested, including the flexural properties of damaged concrete beams strengthened with carbon fiber reinforced polymer, the flexural properties of damaged concrete beams strengthened with prestressed CFRP, and the shear properties of damaged concrete beams strengthened with CFRP. On the basis of experimental research, the calculation methods of flexural capacity, stiffness, crack width and shear capacity of reinforced beams are studied theoretically. The shear strengthening tests of fiber grating and ECC composites are carried out. Through the comparison with ordinary reinforced concrete and carbon fiber reinforced concrete specimens, the crack development, ultimate deflection, ultimate bearing capacity and failure mode of different specimens are studied. The experiments show that the research method provides a new idea for the application of new materials such as carbon fiber grating in structural strengthening engineering.

The influence of shape and matrix size on the mechanical properties of the 2D epoxy thin film by Monte Carlo simulation method

In this paper, we studied the effect of the 2D epoxy thin films’ shape with equilateral triangle and square structures, and matrix size Lx × Ly of (10 × 9), (20 × 19), (30 × 29), and (40 × 39) with equilateral triangle structure and (10 × 10), (20 × 20), (30 × 30), and (40 × 40) with the square structure on their mechanical properties [such as strain (ɛ), stress (σ), Young stress (E), and shear strain (G)] by using the Monte Carlo simulation method. The results show that when the shape of the 2D epoxy thin film is changed from an equilateral triangle structure to a square structure, the values of σ, E, and G decreased sharply. In addition, when the matrix size is increased from (10 × 9) to (20 × 19), (30 × 29), and (40 × 39) with an equilateral triangle structure and from (10 × 10) to (20 × 20), (30 × 30), and (40 × 40) with a square structure, σ slightly increased, but E and G decreased slightly. These results prove that the influence of structure shape on the mechanical properties of the 2D epoxy thin film is very large. The strain stress on the epoxy 2D thin film with an equilateral triangle structure and with a matrix size of (30 × 29) has a value of σ = 63.3 MPa. This result is consistent with the experimental result that σ of bulk epoxy has the maximum value of σmax = 64.76 MPa. The results are the basis for experimental research in future studies on practical applications of epoxy-thin films. In these cases, when thin films with equilateral triangle structures are used in biomedical fields, high stresses are required (such as replacement material for adaxial onion epidermis and fibrin and collagen with low stress).

Experimental and numerical investigation on the disinfection characteristics of a novel rotor-radial groove hydrodynamic cavitation reactor

Hydrodynamic cavitation was considered as a new efficient and green water treatment technology, which doesn’t produce any disinfection by-products. In the present paper, the disinfection characteristics of a novel rotor-radial groove hydrodynamic cavitation reactor were evaluated. The effects of various rotor speeds, flow rates, and initial bacterial concentrations on the removal of Escherichia coli were analyzed on the basis of experimental research and numerical simulation. The possible mechanism of hydrodynamic cavitation disinfection was explained. 93.3% disinfection rate of Escherichia coli can be obtained at 3900 rpm and 2 m3/h in 20 min for 15 L water of simulated effluent. With the increase of flow rate, the disinfection effect of the reactor was improved based on the cavitation effect and the exposure time of bacteria in the bubble collapse area (passing times). The disinfection of Escherichia coliis based on the micro jet, shock wave, and shear stress generated by hydrodynamic cavitation. The findings of the present study can provide support for the application development of hydrodynamic cavitation disinfection and the theoretical development of rotational hydrodynamic cavitation reactors.

Effects of Number of Atoms and Doping Concentration on the Structure, Phase Transition, and Crystallization Process of Fe1-x-yNixCoy Alloy: A Molecular Dynamic Study

In this study, molecular dynamics simulations are employed to study the influencing factors such as doping concentration, number of atoms, and temperature on the structural characteristics, phase transition, and crystallization of Fe1-x-yNixCoy alloy. The results show that Fe1-x-yNixCoy alloy always exists with three metals, Fe, Ni, and Cu, which are distributed quite evenly according to the ratio of tap phase concentration. In Fe1-x-yNixCoy alloy, there are always six types of links, Fe–Fe, Fe–Ni, Fe–Co, Ni–Ni, Ni–Co, and Co–Co. Calculated results showed with the increases in the doping concentration, the length of links (r) has a constant value and the height g(r) of the Radial Distribution Function (RDF) has a modified value. The process of increasing the concentration of Fe doping, and reducing the concentration of Co doping leads to an increase in crystallization, a decrease in the size (l) of the alloy, and the total energy of the system (Etot) increases and then decreases. Similarly, increasing the number of atoms leads to an increase in crystallization, but with an increase in temperature, the crystallization process decreases (that corresponds to the change in the number of structural units for the Face-centered cubic (FCC), Hexagonal Close-Packed (HCP), Body-centered cubic (BCC), and Amorphous (Amor)). The obtained results serve as a basis for experimental research in developing new magnetic materials in the future.

NUTRITIONAL AND BIOLOGICAL VALUE OF MUSHROOM SNACKS

The paper presents the results of research and scientific substantiation of nutritional and biological value of developed new mushroom chips and snacks. Taking into account the high popularity of snacks, the prospects for the use of artificially cultivated mushrooms due to the valuable chemical composition and useful properties, the global volume of their cultivation, such research is appropriate and relevant. To achieve this goal, the task was to investigate experimentally the chemical and amino acid composition, digestion of protein substances of developed chips and snacks based on edible mushrooms. The research was conducted using modern methods. On the basis of experimental researches, the increased consumer and biological value of the developed mushroom products, and also their low caloric content was proved. It was found that mushroom products increased the enzymatic hydrolysis of protein substances compared to fresh mushrooms at both pepsin and trypsin stage of their hydrolytic cleavage, which contributed to their increase digestibility. The conducted research and developed technologies of mushroom chips and snacks can be used both in the food concentrate branch and in other branches of the food industry.

Dynamic Propagation and Electro-Mechanical Characteristics of New Microcracks in Notched Coal Samples Studied by the Three-Point Bending Test System and AFM

This work extends research on the mechanism of electromagnetic radiation (EMR) induced by coal or rock fractures to the category of microscopic dynamic experimental research. A custom-made three-point bending test system and atomic force microscope (AFM) were integrated to obtain the microdynamic loading test system. The notched coal samples were prepared specially. The dynamic propagation of new microcracks in coal samples was measured, and the propagation velocity was calculated. The morphology and electro-mechanical characteristics of new microcracks were tested. More importantly, the causes of the changes in the electro-mechanical characteristics before and after fracture were analyzed, and the effects of these changes on the EMR were discussed. The results showed that the average propagation velocities during the same time interval are 9.5 μm/s, 12.1 μm/s, and 16.2 μm/s. The elastic modulus of the material at the microcrack edge is generally smaller than that of the material in other locations, while the adhesion and deformation are larger. Moreover, the closer the material is to the microcrack, the higher its surface potential. The electrons generated at the microcrack edge and emitted into the atmosphere, which made the greater potentials of the microcrack edge. Many electrons with different velocities and directions migrate in similar parallel-plate capacitors, which are formed by the relative microscale surface of the coal microcrack tip and have different field strengths, resulting in EMR with complex frequencies and different intensities. This study provides a micro-dynamic experimental basis for research on the electromagnetic radiation mechanism.

HYDRAULIC CONDUCTIVITY DEPENDENCE ON POROSITY OF RAPID FILTERS MEDIA

Important characteristics of the rapid filters media, such as hydraulic conductivity, porosity and filtration rate, are determined on the basis of experimental research, conducted by the authors. The relationship between these parameters, as well as the nature of their variation in the height of the filter bed, and over time during the operation of the structure is defined. The scheme of the developed experimental setup and its operation is presented. It consists of a filter column, sand filter media with initial porosity n = 0,47. Measurements were performed at different initial filtration rates V0 = 4.08 m/h, 6.93 m/h, 9.78 m/h, 13.04 m/h and concentrations of model contaminants С0 = 50 mg/dm3, 100 mg/dm3. Experimental dependences and relationships between the main experimental parameters were obtained according to the measurements results. Namely, the relationships between the porosity and the filter media hydraulic conductivity, between the porosity and the filtration rate were received. The analysis of the received data is carried out in the dimensionless form. The necessary graphs are constructed and the corresponding empirical dependences are determined. The effect of the hydraulic conductivity of granular media and filtration rate reduction while reducing the porosity of sand is confirmed. It is shown that filter media siltation and the filtration rate don’t change significantly at the initial stages of the filtration process. The intensity of these processes increases over time and reaches its maximum at the end of the filtration cycle.

Research of Fluridone's Effects on Growth and Pigment Accumulation of Haematococcus pluvialis Based on Transcriptome Sequencing.

Haematococcus pluvialis has high economic value because of its high astaxanthin-producing ability. The mutation breeding of Haematococcus pluvialis is an important method to improve the yield of astaxanthin. Fluoridone, an inhibitor of phytoene dehydrogenase, can be used as a screening reagent for mutation breeding of Haematococcus pluvialis. This study describes the effect of fluridone on the biomass, chlorophyll, and astaxanthin content of Haematococcus pluvialis at different growth stages. Five fluridone concentrations (0.00 mg/L, 0.25 mg/L, 0.50 mg/L, 1.00 mg/L, and 2.00 mg/L) were set to treat Haematococcus pluvialis. It was found that fluridone significantly inhibited the growth and accumulation of astaxanthin in the red dormant stage. In addition, transcriptome sequencing was used to analyze the expression of genes related to four metabolic pathways in photosynthesis, carotenoid synthesis, fatty acid metabolism, and cellular antioxidant in algae after fluridone treatment. The results showed that six genes related to photosynthesis were downregulated. FPPS, lcyB genes related to carotenoid synthesis are downregulated, but carotenoid β-cyclic hydroxylase gene (LUT5), which plays a role in the conversion of carotenoid to abscisic acid (ABA), was upregulated, while the expression of phytoene dehydrogenase gene did not change. Two genes related to cell antioxidant capacity were upregulated. In the fatty acid metabolism pathway, the acetyl-CoA carboxylase gene (ACACA) was downregulated in the green stage, but upregulated in the red stage, and the stearoyl-CoA desaturase gene (SAD) was upregulated. According to the transcriptome results, fluridone can affect the astaxanthin accumulation and growth of Haematococcus pluvialis by regulating the synthesis of carotenoids, chlorophyll, fatty acids, and so on. It is expected to be used as a screening agent for the breeding of Haematococcus pluvialis. This research also provides an experimental basis for research on the mechanism of astaxanthin metabolism in Haematococcus pluvialis.

Nonlinear Stiffness of Semi-Fixed Dowel Joints in Semi-Integral Bridges

The semi-fixed dowel joint studied in this paper consists of a steel dowel with rubber sleeves and a rubber pad to connect the superstructure and the substructure and to support the main beam. This type of joint is suitably used in retrofitting a jointed bridge with high-stiffness substructure into a semi-integral bridge. This study aimed to investigate the nonlinear stiffness of the joint, which is the key parameter in the retrofitting design. Taking the real joint in a retrofitted semi-integral bridge as a prototype, tests on full-scale models were carried out, in which the wall thickness of the rubber sleeve and the thickness of the rubber pad were taken as parameters. The test results show that the wall thickness of the rubber sleeve is the main factor affecting the radial stiffness and the flexural stiffness of the semi-fixed dowel joint. With the decrease of the wall thickness of the rubber sleeve, the radial stiffness decreases while the flexural stiffness increases. However, the thickness of the rubber pad has little influence on both the radial and flexural stiffness of the joint, and its main role is only vertical loading-bearing. If the longitudinal deformation of the main beam of a bridge under maximum temperature variation is 10 mm as the allowance value of engineering design, the wall thickness of the rubber sleeve for this joint should not be less than 40 mm. At last, on the basis of experimental research and theoretical analysis, the formulas of radial stiffness and flexural stiffness are fitted; it can be used as reference for practical engineering application, or for formulation of relevant specifications.

Research on Steering Vibration Analysis of Wheel Loader and Cushion Valve Design

At present, the wheel loaders on the market have steering vibration problems, which can be summarized as follows: the front frame and the cab vibrate violently at the beginning and at the end of steering. This paper analyzed the steering vibration mechanism by collecting the pressure at different positions of the hydraulic steering system and AMESim simulation. A cushion valve was designed to solve the problem of steering vibration. Finally, the prototype test was carried out and it was concluded that the cushion valve reduced the steering pressure starting shock by 50%, the stop vibration was reduced by 75%, and the suction problem no longer occurred. Further, the analysis provides theoretical and experimental basis for research on the steering system of loaders, and also provides new ideas for the design and optimization of vehicle steering systems.

Evaluation of fracture behavior of high-strength hydraulic concrete damaged by freeze-thaw cycle test

Hydraulic concrete structures in cold regions are vulnerable to freeze–thaw (FT) damage, which will affect the fracture performance of concrete structures. Hence, the fracture characteristics of high-strength hydraulic concrete subjected to different FT damage (0, 100, 200, 300, 400 FT cycles) are studied by experimental analysis and discrete element method (DEM) simulation. The results show that the FT damage has a significant weakening effect on the fracture characteristics of concrete beams. The elastic modulus E, critical crack length ac, fracture toughness KIc, fracture energy GF and critical crack tip opening displacement CTODc of concrete beams all show a linearly decreasing trend with the increase of the number of FT cycles. In addition, digital image correlation (DIC) and acoustic emission (AE) techniques are used to reveal the evolution law of internal cracks of FT damaged concrete beams under three-point flexural loads. On the basis of experimental research, the influence indexes of FT damage are introduced into DEM parameters, and a fracture model considering real aggregates is established, which can well predict the fracture behavior of concrete beams subjected to different FT cycles.

СЕЛЕКТИВНИЙ МЕТОД ТВЕРДНЕННЯ ЕПОКСИДНИХ СПОЛУЧНИКІВ ДЛЯ СТВОРЕННЯ ТОНКОСТІННИХ ВИСОКОМІЦНИХ КОНСТРУКЦІЙ

Purpose To improve the physical and mechanical characteristics of the epoxy composition, reduce energy consump-tion, cost, reduce production areas, as well as protect the environment, for the hardening thin-walled structures made of polymer composite materials, it is necessary to choose the most rational method for curing polymer composite materials. Methodology The prepared samples of the epoxy binder ЭДТ-10+УП606/2(1%) with a size of 10х10х10 mm, were hardened by convective, IR heating, and selective IR heating according to specified modes. IR heating is provided by unit with three halogen incandescent lamps type КГТ-220-1000-1 inside and using a salt filter. The mode of composition hardening according to three technologies has been developed. Findings The results of measurements of the cured samples showed that the highest microhardness was achieved using selective IR heating. Metallographic studies has shown that polymer obtained a compact structure with a high degree of hardening, approximately 97%. Hardened samples of ЭДТ-10 epoxy binder were subjected to mechanical tests. Having determined the microhardness, it was found that during the selective hardening of the ЭДТ-10 binder, the microhardness was 34,57 kgf/mm2, IR heating - 30,85 kgf/mm2, convective heating – 29,61 kgf/mm2. Originality To obtain the maximum specific power from the IR emitter, salt filters were used, in which the main part of the emitted energy fell on the wavelength (2,8 – 3,2)•10-6 м. This technique allows you to select the necessary frequency bands. Practicalvalue The results of epoxy composition samples hardening experiment showed that the hardening process by the IR heating selective method takes 1 hour and 15 minutes, in contrast to convective heating which requires at least 7 hours and IR heating with 2 hours and 30 minutes. The selective method provides a uniform temperature distribution over the entire surface to be treated, which ensures high physical and mechanical characteristics. Conclusions On the basis of experimental researches with help selective method IR of hardening samples from PCM have been received on the basis of epoxy binding which possess high mechanical durability and compact structure in comparison with a composition which hardening a traditional convection heating.

Study on controlled rolling and cooling process of CH1T steel High speed wire 1# shaoguan steel

Under the background that the high-grade industrial wire rod such as cold heading steel is mainly developed in the first line of Shaoguan Iron and Steel Co., Ltd., the controlled rolling and controlled cooling process of ultra-low carbon cold heading steel ch1t is studied in this paper. A large number of high-temperature tensile tests for CH1T are carried out on Gleeble 3800 thermal simulation testing machine, and the high-temperature plastic characteristics of CH1T and stress-strain curves at different temperatures are obtained, At the same time, the transformation points Ac1, Ac3, Ar1 and Ar3 of ch1t steel and the dynamic CCT curve were measured, and the process improvement measures were formulated on the basis of experimental research. The field practice shows that the proposed process improvement measures have greatly improved the problem of low yield of ch1t cold heading steel in the first high line of Shaoguan Iron and Steel Co., and achieved remarkable economic benefits.