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OLED materials based on thermally activated delayed fluorescence have promising efficiency. Here, the authors investigate an organometallic multicore Cu complex as luminophore, by pump-probe X-ray techniques at three different facilities deriving a complete picture of the charge transfer in the triplet excited state.

The subject matter of the research in the article is the process of restoring the quality and accuracy of the working surface of the wheelsets of the main electric locomotives, electric sections. The purpose of the work is to develop a modeling method for a special shaped cutter with increased productivity, designed to process the profile of locomotive railway wheels taking into account the shaping processes, which is based on the theory of modeling the high-speed milling process through the shaping efficiency coefficient. The article solves the following tasks: substantiation of the importance of upgrading the most promising designs of "duplex" mills, taking into account the reduction of vibrations due to chip crushing, to increase tool wear resistance, machining accuracy, reduce tool readjustment time and, accordingly, reduce equipment downtime, increase processing productivity, determine the mathematical apparatus for calculating model parameters; development of a method for modeling and optimization of shaping processes in the processing of locomotive wheel sets. Such methods were used: fundamentals of system analysis, simulation method. The following results were obtained: the design of a "duplex" milling cutter with a predicted increase in resistance and increase in processing productivity due to modeling of forming processes with a decrease in the sliding angle by three to five times, which was not previously taken into account when designating and selecting cutting parameters, is provided. It is concluded that the model design of the cutter, taking into account "duplex" and the tribological process of modeling shaping during processing, can increase the resistance of the cutters and ensure the full operation of all cups of the cutter. The forming component of the cutting conditions was evaluated taking into account the coefficient of efficiency of the process of forming the surface layer of the machined wheel. The conclusion was made about the need to create new processes of shaping the design and modernization of tools. Various ways of modeling tool systems are considered. A method for creating a "duplex" cutter model is defined. A "duplex" mill is considered and design features of the algorithm for creating such tools are given. The functioning of the shaping parameters during the processing of locomotive wheelsets is formalized in the form of separate mathematical models and formulas, on the basis of which a method for modeling the process of increasing productivity and increasing the resistance of mills is described. Findings: Thus, a new method was created for modeling the process of shaping when machining wheel sets of locomotives with a "duplex" cutter with minimizing the cost of operating the tool and reducing the sliding angle on the arc of cutting the cutter cup with an increase in the quality and accuracy of processing, which makes it possible to significantly reduce the cost of preparing the production and increase processing efficiency.

Electrochemical characterization of the novel sodium iron titanate Na0.9Fe0.45Ti1.55O4 was performed upon cycling in the Li-ion half-cell. The material exhibited stable cycling in the voltage range 2–4.5 V, and the number of alkali ions extracted per formula unit was approximately half of the Na stoichiometry value. Using laboratory X-ray absorption spectrometry, we measured operando Fe K-edge X-ray absorption spectra in the first 10 charge–discharge cycles and quantified the portion of charge associated with the transition metal redox reaction. Although 3d metals are commonly accepted redox-active centers in the intercalation process, we found that in all cycles the amount of oxidized and reduced Fe ions was almost 20% less than the total number of transferred electrons. Using density functional theory (DFT) simulations, we show that part of the reversible capacity is related to the redox reaction on oxygen ions.

The subject matter of the research is issues related to the optimization of the technology for reconditioning large-size high precision gear rims of the drives of mining complexes, mine lifting equipment, heavy vehicles; these issues are a perspective trend for reducing the cost of reconditioning and operation of expensive unique equipment. The goal is to ensure intensifying production processes, increasing workloads and speeds, reducing the deterioration of high precision gear rims. The objective is to develop a new technology to optimize reconditioning large high precision gear rims. To achieve this, the following method is suggested – to machine gear rims after they have been surfaced by pre-milling with special hob cutters with a prominence and by final machining the teeth with special cutters equipped with hardmetal inserts that process teeth along the line of engagement, which does not require making full-length cutting teeth and increases the quality of machining, the durability of hardmetal milling cutters. The process of reconditioning of large high precision gear rims is a resource-saving technology, as compared with manufacturing new parts, this technology considerably reduces the cost of materials for manufacturing, decreases a number of process steps, reduces the cost of machining equipment, tools, cutting and measuring instruments. The smooth operation of a gear train can be ensured only at a constant gear ratio but due to manufacturing and operational errors, the gear ratio is not constant at every time, which intensify the deterioration of large high precision gear rims. The following results are obtained. The possibility and practicability of using hob cutters with a prominence (m = 20-28 mm) while rough cutting the worn and reconditioned large gear rims was proved. To obtain the necessary durability of rough milling cutters, it is recommended that the prominence angle be set within 8-10°. The use of hardmetal hob cutters for finishing makes it possible to increase the performance rate by 2 to 3 times as compared to high-speed cutters of other designs and to obtain the necessary quality and precision of manufacturing worn and reconditioned large gear rims. Conclusions. The technology for the optimization of reconditioning large high precision gear rims with the use of special and universal hardmetal single- and double-flute cutters that have both re-sharpened cutting elements and disposable rotary tools was developed and introduced.

A rigorous and consistent approach is demonstrated to develop a model of the 4M structure (the four-media structure of a film on a substrate of finite thickness). The general equations obtained for the reflectance and transmittance spectra of the 4M structure are simplified by employing a procedure of the so-called device averaging to reduce them to a succinct form convenient for processing of experimental spectra for the structures with a thick substrate. The newly derived equations are applied to two special cases: (i) an arbitrary film on highly absorbing substrates and (ii) a slightly absorbing film on transparent substrates. The reflectance and transmittance spectra represented in the simplified (with the device averaging) form have a practical application for determining the film thickness and optical constants from experimental spectra by using the known techniques.