Due to the increasing problem resulting from environmental pollution with heavy metals, great emphasis is placed on the development of removal methods of these pollutants from the environment. This study presents a literature review on the methods for the removal of nickel ions from aqueous solutions such as sorption, especially using low-cost sorbents which are very popular in 21���� century, electrochemical processes and membrane techniques. It is often impossible to use a single technique for efficient removal of heavy metals from wastewater as the process depends on many factors, such as wastewater composition, pH, temperature and many others. The aim of this review is to present some selected removal techniques of nickel(II) from wastewater from the point of view of their efficiency and applicability.

This paper presents the modeling and simulation of a novel topology of quasi Z-Multilevel Inverter with stepped DC input. The proposed inverter incorporates a simple switching technique with reduced component count and is aimed at producing boosted multilevel output AC voltage. The inverter consists of two stages and the buck /boost operation is obtained by varying the shoot through period of the pulses obtained by maximum constant boost control with third harmonic injection. With all the advantages of the quasi Z-network, the proposed inverter eliminates the fly back diodes and capacitors present in a conventional Z-Multilevel Inverter. Further the stress on the devices is less which leads to reduction in component value and hence the cost. The novel stepped DC coupled Single Phase quasi Z-Multilevel Inverter is modeled and simulated in the MATLAB – SIMULINK environment and its performance is analyzed for varying input and switching conditions. The voltage and current waveforms across each stage of the inverter is analyzed and the results are presented for different levels of input.

The aim of the article is to discuss the written legacy of Philaret Drozdov, the Orthodox Metropolitan of Moscow (lived 1782–1867), in the context of human freedom and the freedom of the imperial Russia’s system – the autocracy. The basic research material constitutes of four homilies by Philaret Drozdov written in the years 1849–1856. To present a certain evolution of the Russian thought the author of the article also cites works which were created in earlier periods, i.e.: in the Moscow Russia time and in the time of Peter I. First, the author presents the orthodox anthropology as the ideological base for Philaret Drozdov’s considerations of freedom and power. Then, individual texts are discussed in detail in order to define the view of the Metropolitan of Moscow on the foregoing issues. At the end, the author sums up the carried out analysis and presents conclusions.