Felsic magmatism has occurred over a large region of East Asia since Jurassic times and has provided important mineral resources such as tin, tungsten, base metals and gold. The circum-Japan Sea region preserves various geological records of active continental margins, including Jurassic to Early Tertiary magmatic arcs and subduction zones and pre-Jurassic continental basements, which were separated by the opening of the Japan Sea during the Miocene. The felsic magmatism in this region shows a wide variation in terms of redox state and related mineralisation, encompassing east–west contrasts around the Pacific Ocean. A review of granitoids and associated ore deposits in this region indicates that the character of the crust, sedimentary versus igneous, is an essential factor to control the redox state, and a tectonic setting may be an additional factor in some cases.The reduced-type granitoids, characterised by tin mineralisation, were generated in carbonbearing sedimentary crust which was composed mainly of accretionary complex material and not influenced by previous magmatism. Involvement of sedimentary materials is corroborated by oxygen, sulphur and strontium isotope data. The oxidised-type granitoids, characterised by gold or molybdenum mineralisation, were generated in igneous crust which was depleted in reducing agents as a result of previous magmatism. Granitoid magmatism in a given area tends to become more oxidised with time.Jurassic accretionary complexes in East Asia are thought to have been largely displaced from the original place of accretion and stacked up against the northeastern margin in the Khingan and Sikhote–Alin Mountains. This region, dominated by sedimentary crust, was subsequently subjected to Cretaceous felsic magmatism and converted to a large province of reduced-type granitoids and tin–tungsten mineralisation. Diverse geodynamic processes, including the change of the arc-trench system, the creation and collapse of the back-arc basin and the collision of continents, may have prepared many favourable sites for the generation of reduced-type granitoids in northeast Asia. These processes may have resulted in a remarkable contrast with the Pacific margin of North America, where repeated arc magmatism during the Mesozoic formed granitoid batholiths of the oxidised-type.The granitoid types may also be controlled by the tectonic setting and mode of magma emplacement. In the northern Kitakami area of Northeast Japan, Early Cretaceous episodic magmatism occurred in a Jurassic accretionary complex, and formed the oxidised-type granitoids accompanied by submarine bimodal volcanism associated with kuroko mineralisation. Granitoids of fissure-filling type emplaced under extensional environments may be oxidised, irrespective of basement geology, because of insignificant crustal input.

Objective: The aim was to develop a simple, rapid, less expensive, linear, precise, and accurate reverse phase high performance liquid chromatography method for determination of nifedipine in tablets. Methods:The chromatographic analysis of nifedipine was performed using liquid chromatograph Agilent 1290 Infinity II LC System. Selected conditions were isocratic elution with binary mobile phase consisting of solution methanol and 0.1% trifluoroacetic acid (55:45). Detection was carried out using spectrophotometric detector at 265 nm. The method was validated as per ICH guidelines. Results:The retention time for nifedipine by proposed high performance liquid chromatography (HPLC) method is observed as 3.5 minutes. The correlation coefficients are 1.0000. The developed chromatographic method was found to be accurate with recovery 99.2-99.8% and was found within the acceptance criteria (i.e. 98.0-102.0%) with acceptable % relative standard deviation of not more than 2% at each level. The assay results of nifedipine in tablets by developed method are highly reproducible, reliable and are in good agreement with the label claim of the medicines (average 99.62 %).Conclusion: Finally, it should be noted that a new simple, rapid, linear, precise, accurate HPLC method was developed and validated for the determination of nifedipine in medicines in accordance with the ICH guidelines. These results show the method are accurate, precise, sensitive, economic, and rugged. The proposed HPLC method is rapider (retention time is 3.5 minutes). This method can be useful for the routine analysis of nifedipine in pharmaceutical dosage form.

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We consider various engineering methods of calculating the parameters of machines. We carried out experimental tests on laboratory specimens of the stages of a gas expansion engine and a compressed air motor (PEE). Relations are given here for determining the indicated power of a PEE with combined and countercurrent gas distribution systems as well as the main propositions of the procedure for engineering calculations.Possible applications of self-acting valves in the gas distribution systems of high-pressure piston gas-expansion machines [1] as well as in low-pressure expansion engines (expansion engine/compressor units [2] and compressed air motors [3,4]) are being explored at present: laboratory and prototype specimens embodying the technique indicated are being studied. This requires the development of reliable methods of designing and checking the calculations of the principal parameters of the machines. It can be shown with some reliability that the methodology of piston compressor and expansion engine design includes making design computations by simplified engineering methods that involve mathematical models of varying complexity [5].Engineering methods of computation have made it possible to determine the principal parameters of the machine (diameters D cyl and number z cyl of cylinders, the shaft speed, piston stroke, etc.) and individual subassemblies, e.g., gas distribution system. Mathematical models of the working processes of piston machines are implemented as computing software. Using multifunctional analysis, the software can determine the influence of many parameters (output, refrigerating capacity, indicated power, expansion ratio, etc.) and the criteria of their operating efficiency (adiabatic efficiency, refrigerating factor, etc.).The development of engineering methods is based on optimal data in the form of empirical relations and coefficients, obtained from studies of laboratory and prototype specimens of piston expansion engines (PEEs) and their subassemblies.Many researchers have established [1,4,6] that the determining parameters characterize the PEE working cycle and affects a number of important integrated indices (indicated power N i , refrigerating capacity Q, adiabatic efficiency, etc.). That parameter is the degree of filling cutoff (Fig. 1)where S 2 is the piston stroke when the inlet valve closes, m; and S p is the complete piston stroke, m.The degree of filling cutoff is affected by the following parameters:• the valve spring force, which is determined by the total force of the installed springs C sp∑ (N/m) and the spring precompression h 0 (m),

In modern times, new means and techniques for optimising the educational process are required because one of the purposes of professional training is to increase the effectiveness of the educational process. Good‐quality professional training requires the introduction and implementation of modern educational technologies. The authors studied this, using the example of future engineers‐teachers' training, and implementation of modern educational technologies into this process was the purpose of the study. Such methods as analysis, synthesis, empirical method, concretisation, generalisation, survey and questionnaire were used. The aspects of readiness for the introduction of modern educational technologies were studied. The first condition is the readiness of university teachers to organise the process of training future engineers‐teachers with the use of modern educational technologies and their active introduction into the educational process. Another aspect is the development of individual approaches to each student with the use of modern educational technologies. Also, a desire for professional self‐improvement and self‐education should be developed in students which will contribute to successful training. The results of the study allowed to conclude that the level of students' readiness to the introduction of modern educational technologies does not fully meet societal needs.