Effects of Ultrasonic Treatment during the Solidification Process on the Structure Formation of Low Carbon Steel
This paper studied effects of ultrasonic treatment during the solidification process on structure formation of low carbon steel. Results showed that with ultrasonic treatment grains were refined and the steel ingot avoided the cast widmanstatten structure. When ultrasonic treatment was employed, pearlite was broken and the average length of pearlite was decreased from 550 mm to 140 mm. The corresponding aspect ratio was reduced from 12 to 1. At high magnification the treated pearlite was cloud-like, rather than plate-like, as normal. Ultrasonic treatment also can remove the gas from low carbon steel. These phenomena of low carbon steel generated by ultrasonic treatment were explained. [doi:10.2320/matertrans.M2011091]
Effects of the Ultrasound Treatment on Reaction Rates in the RH Processor Water Model System
Ruhrstahl–Heraeus (RH) processor is widely applied to the refining process to produce steel with very low carbon contents. In this study, to investigate the effect of ultrasound treatment on RH decarburization process, we have developed two kinds of the water models simulated the RH process and study the removal rate of dissolved oxygen. The one is the RH water model of 1/8 size of actual RH degasser simulated the late-stage of the RH process when surface reaction and plume reaction mainly occur. Through this model, it is found that the ultrasound treatment accelerates dissolved oxygen removal reaction and this tendency is maintained even at low concentrations. Also, the results show that there is a difference in the degassing efficiency depending on the frequencies and the positions of the ultrasonic transducer. Also, to simulate the Early-stage Reaction of the process including the inner-site reaction which is difficult to investigate through the RH water model, the other water model has been developed (the RH-ER water model). This model shows that the ultrasound treatment facilitates the early-stage reaction including inner-site reaction, like the RH water model. These results show that the addition of the ultrasound treatment can accelerate decarburization reaction during RH process compared to conventional process.
Antimicrobial activity in pulp extract of Neem(Azadirachta indica Linn.)
Antimicrobialactivityin leaf extract of neem ( Azadirachta indica ) against human pathogenic bacteria. E.coli, Staphylococcus aureus, Pseudomonas aeruginosa , Salmonella typhimurium, Bacillus pumilus. Antimicrobia l activities of alcoholic extracts of neem leaves were used. Varying concent ration of each extracts 200mg/ml, 150 mg/ ml,100mg/ml, 50mg/ml, 25mg/ml prepared by using disc diffusion method. When compared with gentamycin 200mg and gentamycin 10mg, the methanol and ethanol extract shows maximum inhibition on Bacillus pumillus, Pseudomonas aeruginosa and Staphylococcus aureusin an asending order.