Plant extract-mediated biogenic synthesis of silver, manganese dioxide, silver-doped manganese dioxide nanoparticles and their antibacterial activity against food- and water-borne pathogens

Krishnaraj, C.,Ji, B. J.,Harper, S. L.,Yun, S. I. Springer Science + Business Media 2016 BIOPROCESS AND BIOSYSTEMS ENGINEERING Vol.39 No.5

<P>Silver nanoparticles (AgNPs), manganese dioxide nanoparticles (MnO(2)NPs) and silver-doped manganese dioxide nanoparticles (Ag-doped MnO(2)NPs) were synthesized by simultaneous green chemistry reduction approach. Aqueous extract from the leaves of medicinally important plant Cucurbita pepo was used as reducing and capping agents. Various characterization techniques were carried out to affirm the formation of nanoparticles. HR-TEM analysis confirmed the size of nanoparticles in the range of 15-70 nm and also metal doping was confirmed through XRD and EDS analyses. FT-IR analysis confirmed that the presence of biomolecules in the aqueous leaves extract was responsible for nanoparticles synthesis. Further, the concentration of metals and their doping in the reaction mixture was achieved by ICP-MS. The growth curve and well diffusion study of synthesized nanoparticles were performed against food- and water-borne Gram-positive and Gram-negative bacterial pathogens. The mode of interaction of nanoparticles on bacterial cells was demonstrated through Bio-TEM analysis. Interestingly, AgNPs and Ag-doped MnO2 NPs showed better antibacterial activity against all the tested bacterial pathogens; however, MnO(2)NPs alone did not show any antibacterial properties. Hence, AgNPs and Ag-doped MnO2 NPs synthesized from aqueous plant leaves extract may have important role in controlling various food spoilage caused by bacteria.</P>

Molecular interactions of graphene with HIV-Vpr, Nef and Gag proteins: A new approach for treating HIV infections

Navanietha Krishnaraj Rathinam,Chandran Saravanan,Pal Parimal,Varalakshmi Perumal,Malliga Perumal 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.5

Graphene draws considerable attention among biomedical researchers because of its unique physical, chemicaland biological properties. The wide applications of graphene in the biomedical arena such as diagnostics, drug immobilizationand drug delivery were well documented in the literature. However the therapeutic potential of the graphenetowards retroviruses and the interactions of the graphene with receptors/proteins are still unexplored. Herein we reportthe antagonistic molecular interactions of graphene with the three key target proteins of HIV infections namely HIVVpr,Nef and Gag proteins. The docking investigations were performed to find the binding energy of the graphene ligandsto the key target proteins of HIV. The high binding affinity of the graphene to these proteins indicates the antagonisticmolecular interaction of graphene to the disease targets. The therapeutic potential of graphene was also studied by changingthe size and the number of layers of the graphene. The experimental results confirm the good therapeutic potential ofthe graphene to combat HIV mediated retroviral infections.

Characterization Study of Zinc Sulphate’s Influence and Retarding Mechanism with Coarser and Finer Fly Ash Particles in Concrete

Loganathan Krishnaraj,Niranjan Ramesh,Rajendran Senthil Kumar,Prem Kumar George 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.9

Pozzolan, a modified cementitious material, has a major impact on the construction industry. Among the different composite materials, fly ash blended cement has great part due to its abundance. In recent years, the pulverized fly ash has become the key interest among the researchers because of its improved physical properties. This makes it necessary to study the effect of fly ash blends with various chemical admixtures. This study primarily focuses on bringing the changes happening in the strength, retarding mechanism, setting time, mineralogy, and microstructure caused by the addition of Zinc Sulphate (ZnSO4) in concrete having various percentages of raw fly ash (RFA) and ultrafine fly ash (UFFA). The result shows that ZnSO4 increases the setting time by more than 60%. Also, the study indicates decreased strength in concrete because of the reduced formation of hydrated products; this phenomenon is confirmed by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and X-ray fluorescence (XRF) analysis.

High throughput de novo RNA sequencing elucidates novel responses in Penicillium chrysogenum under microgravity

Sathishkumar, Yesupatham,Krishnaraj, Chandran,Rajagopal, Kalyanaraman,Sen, Dwaipayan,Lee, Yang Soo Springer-Verlag 2016 BIOPROCESS AND BIOSYSTEMS ENGINEERING Vol.39 No.2

<P>In this study, the transcriptional alterations in Penicillium chrysogenum under simulated microgravity conditions were analyzed for the first time using an RNA-Seq method. The increasing plethora of eukaryotic microbial flora inside the spaceship demands the basic understanding of fungal biology in the absence of gravity vector. Penicillium species are second most dominant fungal contaminant in International Space Station. Penicillium chrysogenum an industrially important organism also has the potential to emerge as an opportunistic pathogen for the astronauts during the long-term space missions. But till date, the cellular mechanisms underlying the survival and adaptation of Penicillium chrysogenum to microgravity conditions are not clearly elucidated. A reference genome for Penicillium chrysogenum is not yet available in the NCBI database. Hence, we performed comparative de novo transcriptome analysis of Penicillium chrysogenum grown under microgravity versus normal gravity. In addition, the changes due to microgravity are documented at the molecular level. Increased response to the environmental stimulus, changes in the cell wall component ABC transporter/MFS transporters are noteworthy. Interestingly, sustained increase in the expression of Acyl-coenzyme A: isopenicillin N acyltransferase (Acyltransferase) under microgravity revealed the significance of gravity in the penicillin production which could be exploited industrially.</P>

Polymorphism in Intrinsic Antibiotic Resistance of Azospirillum Isolates from Ornamental Plants

Gadagi, Ravi,Krishnaraj, P.U.,Kulkarni, J.H.,Ahn, Kisup,Sa, Tongmin 한국환경농학회 2001 한국환경농학회지 Vol.20 No.5

The polymorphism of Azospirillum isolates from ornamental rhizosphere and two reference strains were examined with respect to intrinsic antibiotic resistance (IAR) profile. All the isolates showed different intrinsic resistances to different antibiotics viz., tetracycline, kanamycin, nalidixic acid, streptomycin, ampicillin, spectinomycin and chloramphenicol. All the strains demonstrated susceptibility to high concentration of all antibiotics used in the present experiment. In addition to these general patterns, we also obseved the multiple antibiotic resistances of Azospirillum strains. The Azospirillum sp. OAD-11 was resistant to tetracycline, streptomycin and ampicillin, and Azospirillum sp. OAD-57 was resistant to tetracycline and streptomycin. Conversely, Azospirillum sp. OAD-9 possessed the dual susceptibility to tetracycline and spectinomycin, whereas Azospirillum sp. OAD-37 was dual susceptible to streptomycin and kanamycin. Such multiple antibiotic resistant/susceptible traits could be useful for the identification of the strains in field experiments or in molecular genetic transfer experiments.

Detection of Biologically Synthesized Gold Nanoparticles in Adult Zebrafish (Danio rerio) Using Non-Invasive Photoacoustic Tomography

Palaniappan, Prasannakumar,Krishnaraj, Chandran,Shin, Dong-Ho,Yun, Soon-II,Song, Chul-Gyu American Scientific Publishers 2017 Journal of medical imaging and health informatics Vol.7 No.1

Machining of CFRP/Ti6Al4V stacks under minimal quantity lubricating condition

Senthilkumar M.,Prabukarthi A.,Krishnaraj V. 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.8

Light weight and high strength materials like carbon fiber reinforce plastics (CFRP), Titanium alloys (Ti) and stacks (CFRP/Ti, CFRP/Al, CFRP/Al/Ti) are being extensively used in commercial aircraft. Drilling process on the aircraft components was carried out to facilitate the assembly process. Drilling operations are made under dry condition which leads to tool wear and poor hole quality. In this paper study on drilling of CFRP/Ti6Al4V stacks under minimum quantity lubrication (MQL) using LRT 30 oil with varying flow rate, spindle speed and feed rate have been carried out using three modified drill tool made of solid carbide (K 20) coated with TiAlN. The recital of the tools were evaluated based on hole quality, burr height, thrust force, chip formation and tool wear. It was found that TG1 tool performance was better by producing minimum burr height while drilling Ti. TG2 recital was better by producing minimum force and better hole quality.

Investigation on influence of microtextured tool in machining of Ti-6Al-4V alloy

R. Bibeye Jahaziel,V. Krishnaraj,B. Geetha Priyadarshini 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.4

The low thermal conductivity of titanium alloys, Ti-6Al-4V in specific causes high temperature generation at the tool-chip interface during machining, thus making machining challenging. In view of developing a better heat transfer mechanism at the tool-chip interface, dimple textures have been generated on the rake face of the cutting tool. A comparison was made in terms of cutting force, temperature, shear angle, friction angle, tool-chip contact length, friction coefficient, chip morphology and tool life between commercial and dimple textured tool. Dimple textured tool outperformed the commercial tools in terms of the response parameters. Textures brought about a reduction of 4 %-38 % in cutting forces while a maximum temperature reduction of 20 % was observed at the tool-chip interface. An increase in shear angle by 4-9 % was observed for textured tools when compared to commercial tools. The chip morphology revealed chips with smaller curl radius were generated when machining using textured tools. An increase in tool life by 60 % was observed for textured tools when compared to commercial tools. Reduction in tool-chip contact length by 15 % was attributed to the performance of dimple textured tool.

Rapid Somatic Embryogenesis and Plant Regeneration in American Ginseng: Effete of Auxins and Explants

Wang X.,Proctor J.T.A.,KrishnaRaj S.,Saxena P.K.,Sullivan J.A. The Korean Society of Ginseng 1999 Journal of Ginseng Research Vol.23 No.3

The efficacy of three auxins, viz. 2,4-0, NAA and dicamba, were compared for the induction of somatic embryogenesis in American ginseng (Panax quinquefolium L.). Somatic embryos (SEs) formed on ginseng cotyledonary, zygotic embryo and shoot explants after 8 weeks of induction by the auxin stimuli. Significantly more somatic embryos were induced by culture of any of the ginseng explants on media supplemented with $5{\mu}M$ 2,4-0 than any other auxin treatment. Shoots derived from somatic embryos had the greatest regenerative potential and zygotic embryos the least. Explants generated from green (unstratified) seeds gave similar or higher frequency of embryogenesis as the explants derived from stratified seeds. Histological and SEM studies confirmed that the regenerimts were somatic embryos. Somatic embryos germinated and developed into normal plants in $3\~6$ months. About $10\%$ of plantlets from second generation SEs formed flowers within 10 weeks, particularly on media supplemented with $GA_3$ The development of a regeneration system for ginseng through somatic embryogenesis is a necessary first step for mass propagation and genetic improvement of American ginseng.

Li+ ion conduction in TiO2 filled polyvinylidenefluoride-co-hexafluoropropylene based novel nanocomposite polymer electrolyte membranes with LiDFOB

Vanchiappan Aravindan,Palanisamy Vickraman,Kaliappa Krishnaraj 한국물리학회 2009 Current Applied Physics Vol.9 No.6

This paper describes, nanocomposite polymer electrolyte (NCPE) based on polyvinylidenefluoride-cohexafluoropropylene (PVdF-HFP), which comprises the novel lithium difluoro(oxalato)borate (LiDFOB). Ehtylene carbonate (EC) and diethyl carbonate (DEC) mixture was used as gelling agent and nanoparticulate TiO2 used as filler. The NCPE membranes were subjected to a.c. impedance, tensile strength, Raman studies, TG/DTA and morphological studies. 5 wt% TiO2 comprising membranes exhibited enhanced conductivity of 0.56 mS cm-1and the Young’s modulus was increased from 1.32 to 2.74 MPa. The structural change of α to β phase was confirmed by Raman studies. The thermal stability of the NCPE membrane is found to be 130 ℃. Calculation of activation energy and synthesis of LiDFOB has also been presented. This paper describes, nanocomposite polymer electrolyte (NCPE) based on polyvinylidenefluoride-cohexafluoropropylene (PVdF-HFP), which comprises the novel lithium difluoro(oxalato)borate (LiDFOB). Ehtylene carbonate (EC) and diethyl carbonate (DEC) mixture was used as gelling agent and nanoparticulate TiO2 used as filler. The NCPE membranes were subjected to a.c. impedance, tensile strength, Raman studies, TG/DTA and morphological studies. 5 wt% TiO2 comprising membranes exhibited enhanced conductivity of 0.56 mS cm-1and the Young’s modulus was increased from 1.32 to 2.74 MPa. The structural change of α to β phase was confirmed by Raman studies. The thermal stability of the NCPE membrane is found to be 130 ℃. Calculation of activation energy and synthesis of LiDFOB has also been presented.