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K. C Wickramasinghe,G. I. P. Perera,S. W. M. A. I Senevirathne,Himan KG Punchihewa,Hiroyuki Sasahara 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.12
Metal working fluid (MWF) plays a significant role in metal machining operations to obtain the desired dimensional accuracy and better surface quality in the machined component. Legislations have set limits on the usage of mineral based MWFs because of their carcinogenic behavior and adverse effect on health and the environment. The saturated fatty acid of vegetable oil facilitates a better layer of lubricant between work tool interface compared with the mineral oil based MWFs. This paper describes the surface quality of 0.2 % C and AISI 304 steels while using formulated novel white coconut oil based MWF and mineral oil based MWF in flood cooling and dry machining. The machining parameters were selected according to the recommended specifications, and quality of the machined surface was measured. The novel white coconut oil based MWF has expressed better surface quality for almost all the set of machining parameters compared to other cooling configurations.
Herath, H.M.L.P.B.,Wickramasinghe, P.D.S.U.,Bathige, S.D.N.K.,Jayasooriya, R.G.P.T.,Kim, Gi-Young,Park, Myoung Ae,Kim, Chul,Lee, Jehee Elsevier 2017 FISH AND SHELLFISH IMMUNOLOGY Vol.60 No.-
<P><B>Abstract</B></P> <P>Glutathione reductase (GSR) is an enzyme that catalyzes the biochemical conversion of oxidized glutathione (GSSG) into the reduced form (GSH). Since the ratio between the two forms of glutathione (GSH/GSSG) is important for the optimal function of GSH to act as an antioxidant against H<SUB>2</SUB>O<SUB>2</SUB>, the contribution of GSR as an enzymatic regulatory agent to maintain the proper ratio is essential. Abalones are marine mollusks that frequently encounter environmental factors that can trigger the overproduction of reactive oxygen species (ROS) such as H<SUB>2</SUB>O<SUB>2</SUB>. Therefore, we conducted the current study to reveal the molecular and functional properties of a GSR homolog in the disk abalone, <I>Haliotis discus discus</I>. The identified cDNA sequence (2325 bp) has a 1356 bp long open reading frame (ORF), coding for a 909 bp long amino acid sequence, which harbors a pyridine nucleotide-disulfide oxidoreductase domain (171–246 aa), a pyridine nucleotide-disulfide oxidoreductase dimerization domain, and a NAD(P)(+)-binding Rossmann fold superfamily signature domain. Four functional residues: the FAD binding site, glutathione binding site, NADPH binding motif, and assembly domain were identified to be conserved among the other species. The recombinant abalone GSR (rAbGSR) exhibited detectable activity in a standard glutathione reductase activity assay. The optimum pH and optimal temperature for the reaction were found to be 7.0 and 50 °C, respectively, while the ionic strength of the medium had no effect. The enzymatic reaction was vastly inhibited by Cu<SUP>+2</SUP> and Cd<SUP>+2</SUP> ions. A considerable effect of cellular protection was detected with a disk diffusion assay conducted with rAbGSR. Moreover, an MTT assay and flow cytometry confirmed the significance of the protective role of rAbGSR in cell function. Furthermore, <I>AbGSR</I> was found to be ubiquitously distributed in different types of abalone tissues. <I>AbGSR</I> mRNA expression was significantly upregulated in response to three immune challenges: <I>Vibrio parahaemolyticus</I>, <I>Listeria monocytogenes</I>, and lipopolysaccharide (LPS), thus indicating its possible involvement in host defense mechanisms during pathogenic infections. Taken together, the results of the current study suggest that AbGSR plays an important role in antioxidant-mediated host defense mechanisms and also provide insights into the immunological contribution of AbGSR.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We identified a glutathione reductase homolog (AbGSR) from disk abalone. </LI> <LI> AbGSR resembled functionally important domain architecture of GSR family. </LI> <LI> Recombinant AbGSR confirmed its biochemical properties via enzymatic assays. </LI> <LI> First functional antioxidant properties assessment of a molluscan GSR. </LI> <LI> <I>AbGSR</I> expression was modulated upon induced pathogen stress in gill and hemocytes. </LI> </UL> </P>