A Method to Separate Two Main Antioxidants from Lepidium latifolium L. Extracts Using Online Medium Pressure Chromatography Tower and Two-Dimensional Inversion/Hydrophobic Interaction Chromatography Based on Online HPLC-DPPH Assay

Free radicals, including 1,1-diphenyl-2-picrylhydrazyl, mediate oxidative stress to cause many chronic diseases (including cardiovascular diseases, diabetes and cancer). The extract of traditional Tibetan medicine Lepidium latifolium L. (L. latifolium) was reported to have free radical inhibition ability. Therefore, a system method was established to separate the ethanol extract of L. latifolium to prepare two main antioxidant compounds. First of all, silica gel and a medium-pressure liquid chromatography tower were used for pre-treatment of the ethanol extract of L. latifolium to obtain the main antioxidant active component fraction 4 through online high-performance liquid chromatography-1,1-diphenyl-2-picrylhydrazyl (HPLC-DPPH) assay. Then, fraction 4-1 was obtained by one-dimensional preparation using Megres C18 chromatographic column, and two active compounds with IC50 values 59.9 and 71.3 μg/mL were obtained by two-dimensional preparation using Click XIon chromatographic column. Through the study of the chemical components and separation methods of L. latifolium, the combination of HPLC-DPPH assay and two-dimensional preparative liquid chromatography was realized, providing a reference for the separation of active compounds from L. latifolium.

Water management complexes as objects of recreation and ecological tourism

The article deals with water management complexes, including hydraulic structures and reservoirs. The purpose of the study is to identify the attractiveness, significance and potential of such complexes as objects of recreational and ecological tourism. The analysis of unique hydrotechnical objects of different countries of the world is carried out. The features of their designs and ways to increase the attractiveness of objects for tourists are shown. The simplest and most common method of increasing the recreational potential of a water management facility is the arrangement of species sites. It is much less common to arrange organized recreation areas for participants of the natural tourism route using hydraulic structures or separate entertainment attractions for tourists. Significantly more complex complexes with the inclusion of high-and medium-pressure dams are typical for recreational park areas. A separate group includes objects that serve as historical and educational sites or monuments of history, culture and technology. Thus, the analysis revealed a wide variety of uses of hydrotechnical objects as attractive places for recreation and eco-tourism. The conclusion is made about the expediency of the development of the considered areas of use of water management complexes.

ANALYSIS OF THE DANGER OF EMERGENCY SITUATIONS IN THE CONSTRUCTION AND OPERATION OF GAS BOILER HOUSES

Целью исследований является анализ возможных аварийных ситуаций при разгерметизации газопровода, прилегающего к котельной и находящегося в ней, а также определение горизонтального радиуса действия ключевых поражающих факторов при аварии. В качестве примера произведен расчет аварийной ситуации для участка газопровода среднего давления. Определены значения максимального избыточного давления, импульса фазы сжатия воздушных волн давления и радиусов зон поражения при взрыве топливо-воздушной смеси. Даны рекомендации для профилактики возникновения аварийной ситуации. The purpose of the research is to analyze possible emergency situations during depressurization of the gas pipeline adjacent to the boiler room and located in it, as well as to determine the horizontal radius of action of the key damaging factors in case of an accident. As an example, an emergency situation was calculated for a section of a medium-pressure gas pipeline. The values of the maximum overpressure, the pulse of the compression phase of the air pressure waves, and the radii of the affected areas during the explosion of the fuel-air mixture are determined. Recommendations for the prevention of an emergency are given.

Development of an Integrated Structure for the Tri-Generation of Power, Liquid Carbon Dioxide, and Medium Pressure Steam Using a Molten Carbonate Fuel Cell, a Dual Pressure Linde-Hampson Liquefaction Plant, and a Heat Recovery Steam Generator

Due to the increase in energy consumption and energy prices, the reduction in fossil fuel resources, and increasing concerns about global warming and environmental issues, it is necessary to develop more efficient energy conversion systems with low environmental impacts. Utilizing fuel cells in the combined process is a method of refrigeration and electricity simultaneous production with a high efficiency and low pollution. In this study, a combined process for the tri-generation of electricity, medium pressure steam, and liquid carbon dioxide by utilizing a molten carbonate fuel cell, a dual pressure Linde-Hampson liquefaction plant and a heat recovery steam generator is developed. This combined process produces 65.53 MW of electricity, 27.8 kg/s of medium pressure steam, and 142.9 kg/s of liquid carbon dioxide. One of the methods of long-term energy storage involves the use of a carbon dioxide liquefaction system. Some of the generated electricity is used in industrial and residential areas and the rest is used for storage as liquid carbon dioxide. Liquid carbon dioxide can be used for peak shavings in buildings. The waste heat from the Linde-Hampson liquefaction plant is used to produce the fuel cell inlet steam. Moreover, the exhaust heat of the fuel cell and gas turbine would be used to produce the medium pressure steam. The total efficiency of this combined process and the coefficient of performance of the refrigeration plant are 82.21% and 1.866, respectively. The exergy analysis of this combined process reveals that the exergy efficiency and the total exergy destruction are 73.18% and 102.7 MW, respectively. The highest rate of exergy destruction in the hybrid process equipment belongs to the fuel cell (37.72%), the HX6 heat exchanger (8.036%), and the HX7 heat exchanger (6.578%). The results of the sensitivity analysis show that an increase in the exit pressure of the V1 valve by 13.33% would result in an increase in the refrigeration energy by 2.151% and a reduction in the refrigeration cycle performance by 9.654%. Moreover, by increasing the inlet fuel to the fuel cell, the thermal efficiency of the whole combined process rises by 18.09%, and the whole exergy efficiency declines by 12.95%.