Isolation of Secondary Metabolites from Leucas aspera and Investigation of Biological Activity

Leucas aspera plant was subjected to isolation of secondary metabolites and screening of their biological activities. Four compounds, stigmasterol, lupeol, β-sitosterol and menthol, were isolated from methanol extract. Sixteen different micro-organisms were used for investigating antimicrobial activity of the different extracts of L. aspera where noteworthy zone of inhibition was observed against Gram positive B. subtilis and S. aureus, B. megaterium and Gram negative S. paratyphi, S. typhi, V. mimicus, S. dysenteriae and V. cholera. In brine shrimp lethality bioassay, the highest lethality was showed by crude methanol extract having LC50 values of 4.07μg/mL. The total antioxidant capacity of crude methanol fraction was found to be 59.40 mg/g of plant extract which was maximum comparing with other fractions. No significant cytotoxicity was observed on both HeLa and Vero cell at 1mg/mL sample inhibition. Dhaka Univ. J. Sci. 68(1): 101-104, 2020 (January)

Preliminary studies of a selected group of propellants with potential application in dry fracking technology

The aim of this paper is the selection and study of solid propellants intended for uses associated with the intensification of oil and gas mining, including extraction from shale formations. Results of the study are connected with cooperation with the Department of Shooting Engineering at the Oil and Gas Institute – National Research Institute in Kraków. The basic research is the selection of a group of solid propellants and their modification to the stage where their properties and operating parameters are appropriate for dry fracking. The paper presents research methods for determining the parameters of their propellants in a laboratory-scale rocket motor, e.g. the amount of pressure impulse. Furthermore, an effective electrical system of ignition and a method of appropriate propellant sample inhibition were implemented in order to control the sample combustion process.