Both numerically and experimentally, the possibility of using a combined method to control the incompressible turbulent boundary layer on a symmetric airfoil section of 12-% relative thickness ...implemented via the blowing/suction of air through a finely perforated section provided on the wing surface part was examined. The study was performed at Reynolds number Re
c
= 0.7·10
6
in the range of angles of attack
α
= −6 ÷ 6°. The mechanism of action of this flow control method on the aerodynamic characteristics of the wing was identified. An ambiguous pattern of the effect due to blowing/suction from the viewpoint of ensuring a maximum lift, a gain in wing lift-to-drag ratio, and a reduction of wing aerodynamic drag was revealed.
Steady air blowing (suction) into a turbulent boundary layer on the NACA 0012 airfoil through singular slots located on the opposite sides near the trailing edge is studied experimentally and ...numerically. The investigations are performed at the Reynolds number Re
c
= 0.7 · 10
6
in the range of the angles of attack
α
from −6 to 6°; the intensity of the injected and sucked jet characterized by a dimensionless momentum coefficient does not exceed 10
−3
. It is demonstrated that the result of blowing is not only an increase in the lift force, but also significant enhancement of the drag force of the airfoil. In the case of suction, the increase in the lift force is appreciably smaller despite airfoil drag reduction.
The possibility of using a combined method of control of an incompressible turbulent boundary layer on the NACA 0012 airfoil is studied experimentally and numerically. The method is based on air ...blowing and suction through finely perforated walls, which are parts of the airfoil. The study is performed for Reynolds numbers Re
c
= 0.7 · 10
6
and angles of attack
α
from − 6 to 6°. It is demonstrated that the mechanism responsible for changes in the aerodynamic characteristics of the airfoil is the same for all variants of the control action in the form of air blowing and suction: an increase in pressure due to air blowing on one side of the airfoil and a decrease in pressure due to air suction on the opposite side lead to an increase in the lift force and, finally, to a gain in the lift-to-drag ratio of the airfoil, which reaches three units at
α
≈ 0°. Unfortunately, the efficiency of this method of boundary layer control decreases with increasing
α
.
In the practice of a veterinarian, it is not often, but you have to deal with various injuries and wounds in animals. Burn wounds heal especially hard in animals. And death often occurs from ...intoxication or septicaemia Physiological processes in the body of animals take place at a certain body temperature, which is peculiar only to a certain type of animal. Changes in the thermal parameters of the body lead to pathological changes. And a stronger increase or decrease in body temperature parameters can lead to death. Thermal injuries in animals can be caused by the action of open fire, boiling water, chemicals, ionizing radiation, as well as by improper use of electric heaters or insufficiently grounded plates of electric scooters. A thermal wound is a pathological process with a violation of the integrity of the skin, which leads to a decrease in the basic functions of the body, severe injury and death. The degree of tissue damage depends on the type of active damaging factor, its strength and duration of exposure. 5 Local infectious complications are very common in thermal burns. The resulting infection slows down the healing of burn wounds and contributes to the formation of scars 6. The contamination of wounds with bacteria begins immediately after the burn and consists of conditionally pathogenic bacteria of the environment or the animal’s own biome.
We studied the features of hydrolytic degradation of polylactic acid (PLLA) implants depending on their structural filling with hydroxyapatite (HA). The resistance to
in vitro
hydrolysis was tested ...for the following samples: PLLA without HA (control; group 1), PLLA/HA 25 wt% (group 2), and PLLA/HA 50 wt% (group 3). Samples were incubated at 37°C. In the hydrolysate, lactate, calcium ions, and inorganic phosphate were determined. Additionally, the time of appearance of visual deformation and sample disintegration was recorded. PLLA degradation was higher in samples saturated with HA. The highest resistance to deformation was noted for samples without HA. Samples with a PLLA/HA 50 wt% demonstrated the maximum degradation of PLLA in combination with lower resistance to deformation and the highest bioavailability of calcium and phosphate. Group 2 samples are most promising for clinical use.
In the experiments performed on 16 dogs, an open comminuted tibial fracture was modeled, then wires with hydroxyapatite coating were inserted intramedullary, and osteosynthesis was performed using ...the Ilizarov fixator. Bone regenerates were studied 14-360 days after the surgery using the methods of light microscopy, scanning electron microscopy, and X-ray electron probe microanalysis. It was found that a zone of active reparative osteo- and angiogenesis was formed around the wires, as well as a bone sheath with the properties of osteogenesis conductor and inductor. Fracture consolidation occured early according to the primary type without cartilaginous and connective tissue formation in bone adhesion.
In this study, exfoliated g-C
3
N
4
/NiO nanocomposites were synthesized by the heat treatment of urea and subsequent ultrasonic exfoliation of the colloidal solution with the introduction of nickel ...acetate. Ultrafine nanocomposites were obtained after repeated heat treatment and were marked as initial g-C
3
N
4
, g-C
3
N
4
/NiO 2.5%, g-C
3
N
4
/NiO 5.0%, g-C
3
N
4
/NiO 7.5%, and g-C
3
N
4
/NiO 10%. The successful attachment of NiO to the surface of g-C
3
N
4
was further confirmed by the results of TEM and SAED. The average sizes of the coherent scattering region, determined by the broadening of the reflex (002), were 11.6, 10.4, 10.4, 9.9 and 9.9 nm for the initial, 2.5%, 5.0%, 7.5%, 10% samples, respectively. The obtained powder of graphite-like carbon nitride and the NiO-composites, according to the results of low-temperature nitrogen adsorption, had a mesoporous structure and was characterized by an average pore size of 16.6-20.8 nm and a porosity of 0.40-0.57 cm
3
g
−1
. It was found that increasing the amount of nickel oxide in the composite had a positive effect on the electrochemical characteristics of the electrode during electro-catalytic reforming - hydrogen evolution from a water-alcohol solution. The g-C
3
N
4
/NiO 7.5% nanocomposite showed the best results. Based on voltammetry, it was found that the overpotential of the hydrogen evolution reaction on graphitic carbon nitride equalled 215 mV (at 10 mA cm
−2
) and the Tafel slope was 95 mV dec
−1
. The results of the cyclic voltammetry of the electrode based on exfoliated g-C
3
N
4
indicated its high stability.
In this study, exfoliated g-C
3
N
4
/NiO nanocomposites were synthesized by the heat treatment of urea and subsequent ultrasonic exfoliation of the colloidal solution with the introduction of nickel acetate.
Background. The problem of replacing extensive bone defects remains relevant. The use of implant structures with bioactive properties can stimulate osteogenesis, which will improve the final ...treatment result.The aim of the study. In an in vivo experiment, to study the possibility of replacing an extensive defect in the bone diaphysis with a personal bioactive cellular 3D implant and evaluate the long-term results of its use.Materials and Methods. In an in vivo experiment, adult large mongrel dogs (n = 8) were modeled with an extensive segmental defect of the tibial diaphysis measuring 4 cm. The defect was replaced with a cellular bioactive 3D implant made of titanium alloy Ti6Al4V, manufactured using the additive technology. The diameter of the cells was 1.5 mm on average. The walls of the implant had pores of 100– 300 μm in size. The inner and outer surfaces were coated with a calcium phosphate layer formed by micro-arc oxidation. The primary fixation was provided with the Ilizarov apparatus. In the early postoperative period, antibiotic prophylaxis with broad-spectrum drugs was performed. Clinical, X-ray, histological and statistical methods were used to analyze the results. The main control points were considered: the end of external fixation with the Ilizarov apparatus, after 180 days and 1 year after the termination of external fixation.Results. During the experiment, the death of animals and complications were not observed. The spatial location of the implant was preserved. The formation of a strong bone-implantation block occurred 37.2±6.3 days after the operation. During this period, the external fixation apparatus was dismantled. Osseointegration was provided under conditions of sufficient primary mechanical stability, due to the cellular structure of the implant, the presence of pores on its walls, and the osteoinductive properties of the applied calcium phosphate coating. The achieved degree of osseointegration persisted in long-term periods (6 months and 1 year after the termination of external fixation). The osteoinductive properties of the calcium phosphate coating were confirmed by the expression of osteopontin cells at all stages of the experiment. Outflow of Ca and P from bone fragments was not observed. An elastic sheath was formed on the surface of the implant, similar in structure to the periosteum. The implant cells were filled with a well-vascularized bone substrate. In the projection of the intermediate zone, compact bone tissue was formed, and in the projection of the medullary canal — reticulofibrous bone marrow. This indicates the possibility of organotypic remodeling of bone structures inside the implant.Conclusion. The results of the study showed the effectiveness of using a bioactive cellular 3D implant to replace an extensive defect in the shaft of the bone. The architectonics and osteoinductive properties of the implant surface contributed to the formation of complete osseointegration in a short time, while maintaining the achieved result in long-term periods.
This study aims to investigate the comparative study of calcium phosphate coatings for flexible intramedullary nails (FINs) used to lengthen long tubular bones. The presence of a calcium phosphate ...coating deposited by micro-arc oxidation (MAO) or a composite coating based on a co-polymer of vinylidene fluoride with tetrafluoroethylene (VDF-TeFE) and hydroxyapatite (HA) on the surface of the FIN significantly enhanced the regeneration of bone in the area of osteotomy during limb lengthening by combined osteosynthesis. The investigation of the physico-chemical properties of the FIN coated with calcium phosphate via MAO demonstrated that the improved bone tissue formation resulted from favourable conditions for adhesion, proliferation and differentiation of multipotent stem cells into osteoblasts on the coating surface. The composite coatings only stimulated the formation of bone tissue in vivo, primarily because of the piezoelectric properties of the VDF-TeFE co-polymer.
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