Role of modifiers on the structural, mechanical, optical and radiation protection attributes of Eu3+ incorporated multi constituent glasses

Poojha M.K. Komal,Marimuthu K.,Teresa P. Evangelin,Almousa Nouf,Sayyed M.I. 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.10

The effect of modifiers on the optical features and radiation defying ability of the Eu3þ ions doped multi constituent glasses was examined. XRD has established the amorphous nature of the specimen. The presence of various functional/fundamental groups in the present glasses was analyzed through FTIR spectra. The physical, structural and elastic traits of the glasses were explored. The variation in the structural compactness of the glass structure according to the incorporated modifier was enlightened to describe their suitability for a better shielding media. For the examined glasses, the metallization criterion value varied in the range 0.613e0.692, indicating the non-metallic character of the glasses with possible nonlinear optical applications. The computed elastic moduli expose the Li-containing glass (BTLi:Eu) to be tightly packed and rigid, which is a requirement for a better shielding channel. Furthermore, the optical bandgap and the Urbach energy values are calculated based on the optical absorption spectra. The evaluated bonding parameters revealed the nature of the fabricated glasses covalent. In addition, we investigated the radiation attenuation attributes of the prepared Eu3þ ions doped multi constituent glasses using Phy-X software. We determined the linear attenuation coefficient (LAC) and reported the influence of the five oxides Li2O3, CaO, BaO, SrO, and ZnO on the LAC values. The LAC varied between 0.433 and 0.549 cm1 at 0.284 MeV. The 39B2O325TeO215Li2O310Na2O10K2O 1Eu2O3 glass has a much smaller LAC than the other glasses.

Evaluation of the fracture toughness of brittle hardening materials by Vickers indentation

Rickhey, F.,Marimuthu, K.P.,Lee, J.H.,Lee, H.,Hahn, J.H. Pergamon Press 2015 Engineering fracture mechanics Vol.148 No.-

We propose a Vickers indentation cracking-based method for evaluating the fracture toughness of brittle materials exhibiting strain hardening. The approach is an extension of the recent method by Hyun et al. (2015) for non-hardening materials to hardening materials. The hardening material is simplified by an equivalent non-hardening material with an elevated modified yield strain so that the fracture toughness of a hardening material can be evaluated with the formula proposed by Hyun et al. The proposed extension is verified by comparison with experimental results from nanoindentation tests on Ge(100) and Si(100).

Prediction of cutting force, tool wear and surface roughness of Al6061/SiC composite for end milling operations using RSM

S. Jeyakumar,K. Marimuthu,T. Ramachandran 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.9

The results of mathematical modeling and the experimental investigation on the machinability of aluminium (Al6061) silicon carbide particulate (SiCp) metal matrix composite (MMC) during end milling process is analyzed. The machining was difficult to cut the material because of its hardness and wear resistance due to its abrasive nature of reinforcement element. The influence of machining parameters such as spindle speed, feed rate, depth of cut and nose radius on the cutting force has been investigated. The influence of the length of machining on the tool wear and the machining parameters on the surface finish criteria have been determined through the response surface methodology (RSM) prediction model. The prediction model is also used to determine the combined effect of machining parameters on the cutting force, tool wear and surface roughness. The results of the model were compared with the experimental results and found to be good agreement with them. The results of prediction model help in the selection of process parameters to reduce the cutting force, tool wear and surface roughness, which ensures quality of milling processes.

Effect of Kombucha Tea on Aflatoxin B1 Induced Acute Hepatotoxicity in Albino Rats-prophylactic and Curative Studies

Jayabalan, R.,Baskaran, S.,Marimuthu, S.,Swaminathan, K.,Yun, S.E. The Korean Society for Applied Biological Chemistr 2010 Applied Biological Chemistry (Appl Biol Chem) Vol.53 No.4

Kombucha tea is sugared black tea fermented with a consortium of bacteria and yeasts which forms tea fungus (Medusomyces gisevii) for 14 days. Kombucha tea is claimed to have various beneficial effects on human health but very less scientific evidences are available in the literature. In the present study, the prophylactic and curative effect of black tea (unfermented black tea) and kombucha black tea (KBT) on aflatoxin $B_1$ induced liver damage was studied in male albino rats by analyzing hepatotoxicity markers (aspartate transaminase, alanine transaminase, alkaline phosphatase, gammaglutamyl transpeptidase), lipid peroxidation, reduced glutathione and antioxidant enzymes (glutathione-S-transferase, glutathione peroxidase, glutathione reductase, catalase and superoxide dismutase). Histopathological analysis of liver tissue was also carried out. Results revealed that kombucha tea is more potent in preventing hepatotoxicity than unfermented black tea. The mechanism of hepatoprotection offered by KBT treatment may involve the facilitation of both antioxidant and detoxification processes in the liver.

Structural and Mechanical Characterization of Platinum Thin Films Prepared Electrochemically on ITO/Glass Substrate

A. Kathalingam,Karuppasamy Pandian Marimuthu,K. Karuppasamy,Yeon‑Sik Chae,Hyungyil Lee,Hyun‑Chang Park,Hyun‑Seok Kim 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.6

We report the structural characterization and nanomechanical properties of platinum (Pt) thin films prepared through facileelectrochemical synthesis. The Pt thin films were coated onto indium tin oxide (ITO)/glass substrates by two-electrode electrochemicaldeposition at room temperature. They were characterized using X-ray diffraction, scanning electron microscopy,and atomic force microscopy for structural and morphological analyses. Indentation depth-dependent hardness and elasticmodulus of the prepared films were analyzed using the nanoindentation technique. Furthermore, the mechanical propertiesof the ITO/glass substrates were also investigated to understand the influence of the substrate on the film properties. Theprepared films showed reasonable mechanical and structural properties suitable for device applications. Finally, the photoconductivityeffect of the prepared Pt film was also studied to determine its suitability for device applications. The Pt filmwas also coated on Cu plates to check substrates effects on this electrochemical deposition, and found that the Cu platesproduced well adherent smooth films.

Molecular characterization of two alkylresorcylic acid synthases from <i>Sordariomycetes</i> fungi

Ramakrishnan, Dhivya,Tiwari, Manish K.,Manoharan, Gomathi,Sairam, Thiagarajan,Thangamani, Rajesh,Lee, Jung-Kul,Marimuthu, Jeya Elsevier 2018 Enzyme and microbial technology Vol.115 No.-

<P><B>Abstract</B></P> <P>Two putative type III polyketide synthase genes (PKS) were identified from Sordariomycetes fungi. These two type III PKS genes from <I>Sordaria macrospora</I> (SmPKS) and <I>Chaetomium thermophilum</I> (CtPKS), shared 59.8% sequence identity. Both, full-length and truncated versions of type III PKSs were successfully cloned and overexpressed in a bacterial host, <I>Escherichia Coli</I> BL21 (DE3) using a N-terminus hexa-histidine tag. The full-length and the truncated construct of PKSs showed similar activity profiles, suggesting that additional amino acid residues at the C-terminal of both SmPKS and CtPKS may not be involved in catalytic functions. We demonstrate that these two recombinant polyketide synthases could efficiently synthesize tri- and tetraketide pyrones, resorcinols and resorcylic acids using various acyl-CoAs (C<SUB>4</SUB>–C<SUB>20</SUB>) as starter units. The truncated <I>S. macrospora</I> polyketide synthases (TrSmPKS) showed a maximum of 7.0 × 10<SUP>4</SUP> s<SUP>−1</SUP> M<SUP>−1</SUP> catalytic efficiency towards stearoyl-CoA.Whereas, truncated <I>C. thermophilum</I> polyketide synthases (TrCtPKS) preferred the long-chain acyl-CoA starter arachidoyl-CoA, to produce pentaketide and hexaketide resorcinols with a high catalytic efficiency of 6.2 × 10<SUP>4</SUP> s<SUP>−1</SUP> M<SUP>−1</SUP>. Homology model and substrate docking analyses suggest a shorter distance between sulfur of catalytic Cys152 and thioester carbonyl group of arachidoyl-CoA as well as stronger imidazolium–thiolate ion pair distance in TrCtPKS between catalytic Cys152-His309 compared to TrSmPKS- arachidoyl CoA complex. Enhanced binding interactions of CtPKS residues forming intermolecular contacts at the active site could be attributed to its high specificity towards arachidoyl-CoA. This study reports the functional characterization of two fungal type III polyketide synthases, SmPKS and CtPKS with high catalytic efficiency from S. <I>macrospora</I> and C. <I>thermophilum</I> respectively. Furthermore, the results suggested that the both SmPKS and CtPKS could be attractive targets for protein engineering to discern the unique substrate specificity and catalytic efficiency.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The study reports the functional characterization of two fungal type III polyketide synthases, SmPKS and CtPKS with high catalytic efficiency. </LI> <LI> Both the recombinant PKSs efficiently synthesize pyrones, resorcylic acids and resorcinols using various acyl- CoA (C<SUB>4</SUB>–C<SUB>20</SUB>) as starter units. </LI> <LI> TrCtPKS produces pentaketide and hexaketide resorcinols from arachidoyl-CoA with a high catalytic efficiency of 6.2 × 10<SUP>4</SUP> s<SUP>−1</SUP> M<SUP>−1</SUP>. </LI> <LI> Enhanced binding interactions of CtPKS residues forming intermolecular contacts at the active site could be attributed to its high specificity. </LI> </UL> </P>

Biochemistry ; Effect of Kombucha Tea on Aflatoxin B1 Induced Acute Hepatotoxicity in Albino Rats-prophylactic and Curative Studies

R. Jayabalan,S. Baskaran,S. Marimuthu,K. Swaminathan,S. E. Yun 한국응용생명화학회 2010 Journal of Applied Biological Chemistry (J. Appl. Vol.53 No.4

Kombucha tea is sugared black tea fermented with a consortium of bacteria and yeasts which forms tea fungus (Medusomyces gisevii) for 14 days. Kombucha tea is claimed to have various beneficial effects on human health but very less scientific evidences are

Effect of Kombucha Tea on Aflatoxin B1 Induced Acute Hepatotoxicity in Albino Rats-prophylactic and Curative Studies

( R. Jayabalan ),( S. Baskaran ),( S. Marimuthu ),( K. Swaminathan ),( S. E. Yun ) 한국응용생명화학회 2010 Applied Biological Chemistry (Appl Biol Chem) Vol.53 No.4

Kombucha tea is sugared black tea fermented with a consortium of bacteria and yeasts which forms tea fungus (Medusomyces gisevii) for 14 days. Kombucha tea is claimed to have various beneficial effects on human health but very less scientific evidences are available in the literature. In the present study, the prophylactic and curative effect of black tea (unfermented black tea) and kombucha black tea (KBT) on aflatoxin B1 induced liver damage was studied in male albino rats by analyzing hepatotoxicity markers (aspartate transaminase, alanine transaminase, alkaline phosphatase, gammaglutamyl transpeptidase), lipid peroxidation, reduced glutathione and antioxidant enzymes (glutathione-S-transferase, glutathione peroxidase, glutathione reductase, catalase and superoxide dismutase). Histopathological analysis of liver tissue was also carried out. Results revealed that kombucha tea is more potent in preventing hepatotoxicity than unfermented black tea. The mechanism of hepatoprotection offered by KBT treatment may involve the facilitation of both antioxidant and detoxification processes in the liver.

Mechanical and tribological behavior of the metal matrix composite AA6061/ZrO2/C

R. Pandiyarajan,P. Maran,S. Marimuthu,K.C. Ganesh 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.10

This study investigates the influence of zirconium dioxide (ZrO 2 ) and graphite (C) on the mechanical and tribological behavior of aluminum-based metal matrix composite (AA6061) fabricated through the stir casting. Metal matrix composites (MMC) are prepared with the following weight percentages: 100 % AA; 96 % AA-2 % ZrO 2 -2 % C; 88 % AA-6 % ZrO 2 -6 % C; 92 % AA-6 % ZrO 2 -2 % C; and 96 % AA-2 % ZrO 2 -6 % C. The microstructure and the mechanical and tribological behavior are characterized, and their correlations are obtained. Microstructural studies of the MMC reveal a uniform distribution of ZrO 2 and C particles in the AA6061 matrix. The addition of ZrO 2 improves the hardness from 6 % to 12 % (30 HRC to 40.94 HRC) and the ultimate tensile strength from 8 % to 15 % (128 MPa to 166.3 MPa) of the base metal (AA6061). The tribological behavior of wear and the frictional properties of the MMC are also studied by performing dry sliding wear test using pin-on-disc method. Result shows that the minimum and maximum wear rates of MMC are 5 E-9 and 6.2 E-9 (g/mm), respectively, at speed of 850 rpm and constant sliding distance of 1000 m.

Identification and characterization of type III polyketide synthase genes from culturable endophytes of ethnomedicinal plants

Manoharan, Gomathi,Sairam, Thiagarajan,Thangamani, Rajesh,Ramakrishnan, Dhivya,K.Tiwari, Manish,Lee, Jung-Kul,Marimuthu, Jeya IPC Science and Technology Press 2019 Enzyme and microbial technology Vol.131 No.-

<P><B>Abstract</B></P> <P>Endophytic fungi provide benefits to host plants by producing a diverse class of secondary metabolites (natural products). Arrays of polyketide natural products are synthesized by specific classes of polyketide synthases (PKS I, II and III) in host organisms. In the present study, we attempt to screen and identify type III PKSs in culturable fungal endophytes isolated from the ethno medicinal plants including <I>Arbus precatorius</I>, <I>Bacopa monnieri,Citrus aurantifolia</I> and <I>Datura metel</I> to detect the genetic potential of endophytic fungi in producing bioactive compounds. A total of seventeen endophytic fungal strains belonging to eight genera were identified using fungal morphology and rDNA-ITS phylogenetic analyses. A CODEHOP-PCR based strategy was followed to design degenerate primers for the screening of type III PKS genes from fungal endophytes. We had successfully amplified partial PKS genes from eight endophytes. The amplified PKS sequences showed 60–99% identity to already characterized/putative PKS genes. From the partial sequence of FiPKS from <I>Fusarium incarnatum</I> BMER1, a full-length gene was amplified, cloned and characterized. FiPKScDNA was cloned and expressed in <I>E. coli</I> Lemo21 (DE3) and the purified protein was shown to produce pyrones and resorcinols using acyl-CoA thioesters as substrates. FiPKS showed the highest catalytic efficiency of 7.6 × 10<SUP>4</SUP> s<SUP>−1</SUP> M<SUP>-1</SUP> with stearoyl CoA as a starter unit. This study reports the identification and characterization of type III PKS from endophytes of medicinal plants by CODEHOP PCR.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A CODEHOP PCR based screening method was employed for type III polyketide synthase gene identification in fungal endophytes. </LI> <LI> By this approach, partial type III PKS genes from eight fungal endophytes were amplified and sequenced. </LI> <LI> FiPKS gene from Fusarium incarnatum BMER1, an endophyte of Bacopa monnieri was cloned and functionally characterized. </LI> <LI> FiPKS produced pyrones and resorcinols with the highest catalytic efficiency of 7.6 x 104 s-1 M-1towards stearoyl CoA. </LI> </UL> </P>