Evaluation of crude watermelon oil as lubricant in cylindrical turning of AISI 1525 steel employing Taguchi and grey relational analyses techniques.

Cutting fluids are used for cooling and lubricating the machining area of components used in manufacturing industries such as aerospace, automotive, petroleum, and heavy machinery. Mineral oils derived from petroleum are commonly utilized as cutting fluids. Mineral oil is hazardous to the health of workers and damaging to the environment. There is a need for a substitute for mineral oil. Vegetable oil is increasingly being used as a cutting fluid. Vegetable oils are easily accessible and have benefits including excellent biodegradability, resistance to fire, low humidity rates, and a low coefficient of expansion under heat. This study adopts watermelon oil as a lubricant in MQL machining of AISI 1525 steel using tungsten tools. In the experiment, the feed rate, depth of cut (DC) and spindle speed were varied using the Taguchi L9 orthogonal array. Grey relational analysis was conducted to obtain optimum cutting parameters for surface roughness, machine vibration, and cutting temperature. Hardness and microstructural analysis of the workpiece were also conducted. Results showed that vegetable oil performed much more effectively than mineral oil in most experiments. The DC was shown to be the most efficient cutting parameter after applying ANOVA analysis based on the parameters that were evaluated. Additionally, models for cutting temperature, machine vibration, and surface roughness values have been developed with accuracy between 69.73 % and 99.05 %. The hardness of the workpiece increases with an increase in diameter, which was attributed to the increase in the steel rod (workpiece) cross-sectional area and the likelihood of a more uniform stress distribution. Moreover, finer grain sizes were observed at 70 mm diameter, with the predominant presence of pearlites. These characteristics were reportedly beneficial to the material's toughness and strength.

Inhibitory activities of selected south west Nigerian medicinal plants against mycobacterium tuberculosis.

INTRODUCTION: Tuberculosis (TB), an infectious disease prevalent in the tropics especially in Africa and Asia is one of the highest causes of morbidity and mortality and a global concern. With increasing resistance of the pathogen, to existing antituberculosis drugs and the synergy between TB infection and acquired immune deficiency syndrome (AIDS), the need for development of new drugs to cope with the infection is urgent. OBJECTIVE: Extracts from 16 plants identified and selected from the ethnomedicine of the Ijebus in Southwestern Nigeria as remedies for tuberculosis were evaluated for activity against Mycobacterium tuberculosis, in vitro. METHODOLOGY: Plant extracts were screened against clinical isolate of Mycobacterium tuberculosis using agar plate method on Middlebrook 7H11 medium and observed for 12 weeks. RESULTS: The crude aqueous methanol extracts. showed varying degrees of activity at concentrations of 0.025 - 100 mg/mL. Ocimum grattisimum (leaf) demonstrated the highest activity with minimum inhibitory concentration (MIC) of 0.025 mg/mL. Two standard anti-tuberculosis drugs; rifampicin and isoniazid, included in the assay had MIC values of 0.01 mg/mL and 0.0005 mg/mL, respectively. CONCLUSION: The results of the study confirm the ethnopharmacological uses of some of the plants for TB indicating their potential as sources for the discovery of anti-tuberculosis drugs.

Phytochemical and antimicrobial activities of the wild mango-Irvingia gabonensis extracts and fractions.

Crude methanol extracts obtained from the leaf, stem bark and root of the wild mango, Irvingia gabonensis, were screened for antimicrobial properties by agar well diffusion method at three different concentrations (100 mg/ml, 50 mg/ml and 25 mg/ml) against six human pathogenic microorganisms consisting of four bacteria and two fungi. The hexane, chloroform, ethyl acetate and methanol fractions of the leaf and root methanol extracts were also subjected to the same assay at concentrations of 100 mg/ml-5mg/ml. Gentamicin and Tioconazole were used as positive and methanol as negative controls. Significant inhibitory activities were exhibited by the leaf and root extracts. The crude methanol extract of the root displayed the highest activity at a concentration of 100 mg/ml. It had a diameter of zone of inhibition of 19.7mm while the reference drug had 19.3mm on Pseudomonas aeruginosa, the most sensitive bacteria. The fungi used in this study were also very sensitive to the leaf extract. All the active extracts and fractions exhibited concentration-dependent activities against all the test organisms. Diameter of zones of inhibition ranges from 10.0-30.0 mm. The stem bark was inactive against all the studied organisms. The most active fraction was the ethyl acetate soluble fraction of the leaf which showed a comparable antimicrobial activity against the organisms at concentrations 100 mg/ml and 50 mg/ml comparable to the reference standard drug Gentamicin and Tioconazole. The ethyl acetate soluble fractions of leaf and root were found to show the highest activity. At a concentration of 5 mg/ml, the root ethyl acetate fraction inhibited the growth of all the bacteria tested. The phytochemical screening of the plant materials revealed the presence oftannins, saponins, alkaloids and anthraquinones and the absence of cardiac glycosides. Thin layer chromatography indicated the presence of phenolic compounds.