The 5'-adenosine monophosphate-activated serine/threonine protein kinase (AMPK) is stimulated by energy depletion, increase in cytosolic Ca(2+) activity, oxidative stress, and nitric oxide. AMPK participates in the regulation of the epithelial Na(+) channel ENaC and the voltage-gated K(+) channel KCNE1/KCNQ1. It is partially effective by decreasing PIP(2) formation through the PI3K pathway. The present study explored whether AMPK regulates the renal outer medullary K(+) channel ROMK. To this end, cRNA encoding ROMK was injected into Xenopus oocytes with and without additional injection of constitutively active AMPK(γR70Q) (AMPK(α1)-HA+AMPK(β1)-Flag+AMPKγ1(R70Q)), or of inactive AMPK(αK45R) (AMPK(α1K45R)+AMPK(β1)-Flag+AMPK(γ1)-HA), and the current determined utilizing two-electrode voltage-clamp and single channel patch clamp. ROMK protein abundance was measured utilizing chemiluminescence in Xenopus oocytes and western blot in whole kidney tissue. Moreover, renal Na(+) and K(+) excretion were determined in AMPK(α1)-deficient mice (ampk ( -/- )) and wild-type mice (ampk ( +/+ )) prior to and following an acute K(+) load (111 mM KCl, 30 mM NaHCO(3), 4.7 mM NaCl, and 2.25 g/dl BSA) at a rate of 500 μl/h. As a result, coexpression of AMPK(γR70Q) but not of AMPK(αK45R) significantly decreased the current in ROMK1-expressing Xenopus oocytes. Injection of phosphatidylinositol PI((4,5))P(2) significantly increased the current in ROMK1-expressing Xenopus oocytes, an effect reversed in the presence of AMPK(γR70Q). Under control conditions, no significant differences between ampk ( -/- ) and ampk ( +/+ ) mice were observed in glomerular filtration rate (GFR), urinary flow rate, serum aldosterone, plasma Na(+), and K(+) concentrations as well as absolute and fractional Na(+) and K(+) excretion. Following an acute K(+) load, GFR, urinary flow rate, serum aldosterone, plasma Na(+), and K(+) concentration were again similar in both genotypes, but renal absolute and fractional Na(+) and K(+) excretion were higher in ampk ( -/- ) than in ampk ( +/+ ) mice. According to micropuncture following a K(+) load, delivery of Na(+) to the early distal tubule but not delivery of K(+) to late proximal and early distal tubules was increased in ampk (-/-) mice. The upregulation of renal ROMK1 protein expression by acute K(+) load was more pronounced in ampk (-/-) than in ampk ( +/+ ) mice. In conclusion, AMPK downregulates ROMK, an effect compromising the ability of the kidney to excrete K(+) following an acute K(+) load.
The article analyzes various methods of creating polymer coatings. The following methods of application of polymer powder materials, namely in a pseudo-liquid state, electrostatic, thermojet, gas flame, have become the most widespread in production. Each of the listed methods has its own features and advantages and disadvantages, which determine the scope of their use based on the parameters of the objects to be coated, their structures and features, conditions of future operation, as well as the required thickness of the polymer coating layer. The only factor that unites all methods is the thermal effect in the process of creating a polymer coating, which is necessary for the formation of a strong adhesive bond between the coating and the substrate. The article shows the results of research into the possibility of using a device for gas-dynamic application of metal coatings to create polymer coatings, and its modernization in order to eliminate the identified shortcomings and achieve optimal conditions for the formation of polymer functional coatings. The possibility of a high-speed coating application regime and its influence on the formation of the coating were analyzed. The structure of the researched gas-dynamic device for applying coatings is shown, which contains an electronic heater for the flow of compressed air, and a nozzle assembly for accelerating the heated compressed air in which, due to the ejection effect, the molten polymer material is sucked in and accelerated, which can be in the form of a finely dispersed powder or in the form of a solid dart in the hottest zone with a temperature of about 350 ºС, which contributes to its rapid melting to a liquid state, at the same time, reducing the length of the nozzle to 40 mm allows maintaining the temperature of the polymer material at the level of 230 ºС, which allows the formation of a high-quality coating, while the air pressure is reduced from 0.5 MPa to 0.02 MPa. The conducted studies showed that the use of gas-dynamic sputtering makes it possible to significantly simplify the control and regulation of the heating temperature of polymer materials compared to gas-flame sputtering, due to the possibility of adjusting the temperature of the air flow by changing the current strength on the heating element. Compared to the technology of creating polymer coatings using powder paints, there are also significant advantages associated with the fact that there is no need for long-term heating of these coatings in thermal polymerization chambers. In addition, it is possible to apply polymer coatings on the surface of large-sized products that are not limited by the size of thermal chambers.
This article is devoted to the equipment for gas-dynamic spraying in order to simplify its design, to provide the possibility of adjusting the parameters (temperature, pressure, speed, ejection) of the air-polymer flow, and to clarify the fundamental possibility of creating polymer functional coatings with gas-dynamic spraying. The polymeric materials, depending on their brand, are completely inert and do not react in any chemical reaction with food, animal waste products, acids and other corrosive media. It is known that polymeric materials can be attributed to the two main classes of reactants and thermoplastics. If the thermoplastic process of heating and cooling can occur repeatedly without changing their structure, then reactive plastics with a single heating with increasing time of elevated temperatures as a result of chemical processes occurring in them, transform into an insoluble solid state with the formation of a mesh structure of macromolecules. This process is irreversible, the products of the reactoplasts are destroyed by reheating at a sufficiently high temperature without first softening and thus cannot be recommended for their use in order to create polymer coatings by gas-dynamic sputtering. The characteristics of the most common thermoplastics, such as polypropylene, polyethylene, polytetrafluoroethylene, polystyrene, polyvinyl chloride, polyamides, are analyzed, and the conditions to be created for the successful application of functional polymer coatings. Experimental application of polymer coatings of the most common polymers. The results obtained indicate that the designed and manufactured prototype gasdynamic spraying device is capable of creating different modes of polymer coating. That is to change and maintain the required temperature and pressure of compressed air. The results of the researches show a fundamental possibility to create polymer coatings from thermoplastics on metal surfaces by gas-dynamic spraying.
The article considers a progressive gas-dynamic method for the formation of functional coatings. A theoretical analysis of the methods for applying restorative coatings on the wear of a part was carried out in order to determine the advantages and disadvantages of these methods, the method of gas-dynamic spraying was characterized, and the feasibility of using the technology in industry was determined. This method has a significant advantage over other spraying methods and can be successfully used to improve the performance of units and mechanisms of process equipment. The article determines the optimal size of the sprayed copper and aluminum particles, as well as the required speed for the technological process. The main stages of coating formation by this method are considered. An inspection of modern equipment for gas-dynamic spraying was carried out. A general scheme of the technological process of forming a coating by gas-dynamic spraying has been developed, the dependences of the temperature and velocity of particles depending on the spraying methods have been determined: gas-flame (low-speed); electric arc; gas-flame (high-speed); plasma; detonation; and gas dynamic. The results of calculations and experimental values of the dependence of the speed of aluminum and copper particles on the obstacle surface on the size of these particles are presented. The article defines the typical characteristics of installations for gas-dynamic spraying of powder materials, after which these machines are analyzed to determine the most versatile, cost-effective and efficient installations used in domestic repair departments.
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