Methods of Current Limitation in Low Voltage (up to 1 kV) Electric Networks

The article discusses and systematizes the causes of high values of short-circuit currents in electrical networks up to 1 kV and indicates their negative consequences. A brief analysis of some current limiting methods (both with and without additional investment) is given, which makes it possible to reduce the negative effects when significant short-circuit currents occur. The variants of the implementation of these current limiting methods recommended for study at the design stage or when replacing equipment that has exhausted its resource, are considered. The advantages and disadvantages of the methods of limiting short-circuit currents described in the article are indicated. Options for connecting equipment with low power consumption to nodes of the electrical network up to 1 kV with high values of short-circuit currents are also considered. Special attention is paid to current-limiting protection devices, a detailed description of the design of some of them is given, the advantages of their use in comparison with other current-limiting methods are indicated, the corresponding graphs of the limitation of the periodic component of the short-circuit current, shock short-circuit current and thermal pulse are presented. Based on the analysis of graphic materials, the issue of ensuring the selectivity of protections is considered. The degree of prevalence of equipment with the property of current limitation is determined. A method for determining selective current-limiting protection devices is given, viz. the method of energy selectivity, the corresponding graphs for determining energy selectivity are presented. The physics allowing to determine the degree of efficiency of limiting the short-circuit current is described. Recommendations on the use of current-limiting equipment are proposed.

Lipid-Based Nanocarrier System for the Effective Delivery of Nutraceuticals

Nutraceuticals possess several health benefits and functions; however, most nutraceuticals are prone to degradation in the gastrointestinal environment and have poor bioavailability. Application of a novel carrier system is of increasing importance to overcome obstacles and provide efficient applicability. Lipid-based nanocarriers provide a large surface-to-mass ratio, enhanced intestinal absorption by solubilization in the intestinal milieu, intestinal lymphatic transport, and altering enterocyte-based transport. A critical overview of the current limitation, preparation, and application of lipid-based nanocarriers (liposomes and niosomes) and lipid nanoparticles (SLNs and NLCs) is discussed. Physical and gastrointestinal stability and bioavailability of nanoencapsulated nutraceuticals are considered as well.

Powerful switching DC/DC converter on silicon carbide transistors

The paper deals with the description of operational principles of powerful 16 kW step-down voltage converter for use in the power plant of hybrid aircraft. The BUCK-converter works in a range of input voltages from 1300 to 1000 V and output voltages from 800 to 1000 V with current limitation of 20 A. The efficiency of the converter is about 99 %.