Fluorinated TiO2‑doped, glycine‑functionalized MWCNTs for high‑performance antibacterial agents

Umadevi Mahalingam1,Poornima P. Veerabaghu,Sangari Mayavan,Parimaladevi Ramasamy 한국탄소학회 2019 Carbon Letters Vol.29 No.1

Perennial need for bactericides requires cost-effective nanomaterials with strong antibacterial activities even in the absence of external irradiation. Hence, in this work, we have synthesized f-CFT (fluorinated TiO2-doped, glycine-functionalized MWCNTs) and have studied its antibacterial activities. Both gram-negative and gram-positive bacteria were analyzed in the absence of photo-activation. Zone of inhibition of 15 mm for S. aureus, and 11 mm for P. aeruginosa was observed for f-CFT owing to the synergistic bactericidal properties of functionalized MWCNTs, fluorine and nano-TiO2. Anatase phase TiO2 with average crystallite size as 35 nm was observed in XRD. Scanning electron microscopic images showed uniform mixed cubic structures. Hydroxyl groups observed in FT-IR along with the glycine MWCNTs interface aid the inhibition of bacterial growth even in the absence of photo activation. A desired higher gram-positive bacterial inhibition opens new gates for better antibacterial agents.

Fluorinated TiO2‑doped, glycine‑functionalized MWCNTs for high‑performance antibacterial agents

Umadevi Mahalingam,Poornima P. Veerabaghu,Sangari Mayavan,Parimaladevi Ramasamy 한국탄소학회 2019 Carbon Letters Vol.29 No.1

Perennial need for bactericides requires cost-effective nanomaterials with strong antibacterial activities even in the absence of external irradiation. Hence, in this work, we have synthesized f-CFT (fluorinated TiO2- doped, glycine-functionalized MWCNTs) and have studied its antibacterial activities. Both gram-negative and gram-positive bacteria were analyzed in the absence of photo-activation. Zone of inhibition of 15 mm for S. aureus, and 11 mm for P. aeruginosa was observed for f-CFT owing to the synergistic bactericidal properties of functionalized MWCNTs, fluorine and nano-TiO2. Anatase phase TiO2 with average crystallite size as 35 nm was observed in XRD. Scanning electron microscopic images showed uniform mixed cubic structures. Hydroxyl groups observed in FT-IR along with the glycine MWCNTs interface aid the inhibition of bacterial growth even in the absence of photo activation. A desired higher gram-positive bacterial inhibition opens new gates for better antibacterial agents.

Bandgap tuned and oxygen vacant TiO_2−x anode materials with enhanced electrochemical properties for lithium ion batteries

Kang, Suk Hyun,Jo, Yong Nam,Prasanna, K.,Santhoshkumar, P.,Joe, Youn Cheol,Vediappan, Kumaran,Gnanamuthu, Ramasamy,Lee, Chang Woo Elsevier 2019 Journal of industrial and engineering chemistry Vol.71 No.-

<P><B>Abstract</B></P> <P>As a promising anode material, TiO<SUB>2−x</SUB> is prepared with a low bandgap by adding a zinc powder using a solvothermal reaction. It is homogeneous, spherical, and 30nm in size, changing from anatase to rutile. It shows a high discharge capacity, 253.8mAhg<SUP>−1</SUP>, after 50 cycles at 100mAg<SUP>−1</SUP> whereas the pristine TiO<SUB>2</SUB> material delivers mere 81.1mAhg<SUP>−1</SUP>. The improved electrochemical performance with cycling of the TiO<SUB>2−x</SUB> compared with the pristine TiO<SUB>2</SUB> material is attributed to the presence of Ti<SUP>3+</SUP> and/or oxygen vacancies.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Bandgap tuned TiO<SUB>2−x</SUB> has been effectively prepared via a solvothermal reaction. </LI> <LI> Oxygen vacancy is successfully produced in TiO<SUB>2−x</SUB>. </LI> <LI> The prepared material exhibits excellent rate capability and specific capacity. </LI> <LI> Electronic conductivity and surface area are improved by oxygen vacancy. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Rare earth (Ce³⁺) activated NaMgF₃ phosphor synthesised by hydrothermal method and its optical properties

Daniel, D. Joseph,Raja, A.,Kim, H.J.,Ramasamy, P. Elsevier 2018 OPTIK -STUTTGART- Vol.158 No.-

<P><B>Abstract</B></P> <P>In this paper, we present an environment friendly hydrothermal process to synthesize nano/sub micro particles of the rare earth activated complex fluoride NaMgF<SUB>3</SUB> at 180 °C. The tittle compound synthesis was carried out at elevated pressure and temperature in an aqueous medium. The powder X-ray diffraction pattern was recorded to check the phase purity of the synthesised compound. Synthesized compounds were micro and nanocrystalline with orthorhombic perovskite crystal structure, space group Pcmn. In order to identify the functional groups Fourier Transform Infrared spectral analysis have been performed. The size and shape of the synthesised compounds were studied by using Field Emission - Scanning Electron Microscope images. Chemical composition of the synthesised compounds were checked by the energy - dispersive X-ray spectra. The absorption bands around 220 and 270 nm were observed which is corresponding to the electronic transition between 4f and 5d configuration of Ce<SUP>3+</SUP>. Photoluminescence emission related to the 5 d → 4 f transitions in Ce<SUP>3+</SUP> was observed at 324 nm. Thermoluminescence properties were studied for the X-ray irradiated samples. The glow curve kinetic parameters of activation energy (E) and frequency factor (S) were calculated using standard methods.</P>

Crystal growth, structural, low temperature thermoluminescence and mechanical properties of cubic fluoroperovskite single crystal (LiBaF₃)

Daniel, D. Joseph,Ramasamy, P.,Ramaseshan, R.,Kim, H.J.,Kim, Sunghwan,Bhagavannarayana, G.,Cheon, Jong-Kyu Elsevier 2017 Optical materials Vol.72 No.-

<P><B>Abstract</B></P> <P>Polycrystalline compounds of LiBaF<SUB>3</SUB> were synthesized using conventional solid state reaction route and the phase purity was confirmed using powder X-ray diffraction technique. Using vertical Bridgman technique single crystal was grown from melt. Rocking curve measurements have been carried out to study the structural perfection of the grown crystal. The single peak of diffraction curve clearly reveals that the grown crystal was free from the structural grain boundaries. The low temperature thermoluminescence of the X-ray irradiated sample has been analyzed and found four distinguishable peaks having maximum temperatures at 18, 115, 133 and 216 K. Activation energy (E) and frequency factor (s) for the individual peaks have been studied using Peak shape method and the computerized curve fitting method combining with the T<SUB>max</SUB> <B>-</B> T<SUB>Stop</SUB> procedure. Nanoindentation technique was employed to study the mechanical behaviour of the crystal. The indentation modulus and Vickers hardness of the grown crystal have values of 135.15 GPa and 680.81 respectively, under the maximum indentation load of 10 mN.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The LiBaF<SUB>3</SUB> Single crystal was grown from the melt by using the Bridgman technique. </LI> <LI> Structural perfection was monitored by HRXRD analysis. </LI> <LI> Trap centers were analyzed by Low temperature thermoluminescence spectra. </LI> <LI> Kinetic parameters have been studied by using various standard methods. </LI> </UL> </P>

Rapid (∼10 min) synthesis of single-crystalline, nanorice TiO₂ mesoparticles with a high photovoltaic efficiency of above 8%

Parmar, K. P. S.,Ramasamy, Easwaramoorthi,Lee, Jinwoo,Lee, Jae Sung Royal Society of Chemistry 2011 Chemical communications Vol.47 No.30

<P>A novel rapid (∼10 min) microwave-hydrothermal synthesis is demonstrated for nanorice TiO<SUB>2</SUB> mesoparticles as an anode of a dye-sensitized solar cell with an excellent photovoltaic efficiency of above 8%.</P> <P>Graphic Abstract</P><P>A novel rapid synthesis is reported for single-crystalline, nanorice TiO<SUB>2</SUB> mesoparticles with an excellent photovoltaic efficiency of above 8%. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c1cc12150b'> </P>

Growth of 1 0 0 directed ADP crystal with slotted ampoule

P. Rajesh,P. Ramasamy,G. Bhagavannarayana,Binay Kumar 한국물리학회 2010 Current Applied Physics Vol.10 No.4

Good quality ammonium dihydrogen phosphate single crystals have been grown by: (i) Sankaranarayanan–Ramasamy (SR) method and (ii) SR method with slotted ampoule. The grown crystals were subjected to UV–Vis spectroscopy, high-resolution X-ray diffractometer, dielectric, piezoelectric and laser damage threshold studies. Compared to the (1 0 0) plane of the conventional method grown ADP crystal and (1 0 0) directed SR method grown ADP crystal, the crystal grown by SR method with slotted ampoule has higher growth rate, higher optical transparency, high crystalline perfection, low dielectric loss, high piezoelectric charge coefficient and high laser damage threshold due to diffusion of segregated impurities away from the growing crystal in the slotted ampoule growth.

Ultrasound-assisted chiral derivatization of etodolac with (1R)-(-)-menthyl chloroformate for the determination of etodolac enantiomers

Jin, Y.,Zhao, J.,Rhyman, L.,Ramasami, P.,Shin, Y.,Jeong, K.M.,Lee, J. Elsevier ; King Saud University 2016 Arabian journal of chemistry Vol.9 No.suppl2

<P>This study presents the first report of an ultrasound-assisted derivatization reaction between a carboxylic acid of etodolac (ETO) and a chiral derivatization reagent, (1R)-(-)-menthyl chloroformate (R-MCF). Fifty mu L of deproteinated mouse serum containing ETO enantiomers was derivatized with 125 mu L of 200 mM R-MCF and 17 mu L of pyridine (a catalyst), with the reaction facilitated by ultrasonic radiation for 13 min, which were the optimal conditions as determined by response surface methodology. After quenching the reaction by adding an aqueous L-proline solution, the mixture was subjected to salting-out assisted liquid-liquid extraction (SA-LLE), which provided phase separation for sample concentration as well as cleanup. The ETO diastereomers were separated on a Phenomenex Gemini C-18 column (150 x 4.6 mm, 5 mu m) under a simple gradient elution of a mobile phase containing a mixture of methanol: acetonitrile (10: 1, V/V) and 10 mM acetic acid at a flow rate of 1.0 mL min(-1), followed by fluorescence detection with excitation and fluorescence emission wavelengths of 235 nm and 345 nm, respectively. The developed method was validated for specificity, sensitivity, linearity, accuracy, precision, stability, and matrix effect. A good linearity in the range of 0.5-50.0 mu g mL(-1) for each ETO enantiomer with r(2) > 0.998 and acceptable values for the intra-day and inter-day accuracy and precision as well as negligible matrix effects supported the suitability and reliability of the method. Finally, this method was used to analyze real samples taken from mice treated with (+/-)-ETO. (C) 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of King Saud University.</P>

Hybrid metal-Cu2S nanostructures as efficient co-catalysts for photocatalytic hydrogen generation

Park, J. H.,Ramasamy, P.,Kim, S.,Kim, Y.,Ahilan, V.,Shanmugam, S.,Lee, J. S. Royal Society of Chemistry 2017 Chemical communications Vol.53 No.22

<P>In this communication, we present a new synthesis method for the fabrication of hybrid metal-Cu2S (M = Pt, FePt) nanocrystals (HNs). The metal-Cu2S HNs were investigated in photocatalytic hydrogen generation as effective co-catalysts on TiO2. The Pt-Cu2S/TiO2 catalyst showed a higher hydrogen generation rate compared with a pure TiO2 catalyst. This enhancement is attributed to the synergistic effects between Cu2S and Pt, which significantly improve the light absorption ability and the charge separation activity.</P>

Enhancement of the crystalline perfection of <0 0 1> directed KDP single crystal

P. Rajesh,S. Sreedhar,K. Boopathi,S. Venugopal Rao,P. Ramasamy 한국물리학회 2011 Current Applied Physics Vol.11 No.6

<0 0 1> directed good quality potassium dihydrogen phosphate (KDP) single crystal has been grown by Sankaranarayanan―Ramasamy (SR) method with the vision to improve the crystalline perfection and efficiency. A seed crystal of diameter 25 × 15 × 3 mm^3 was mounted in the ampoule, where the diameter of the ampoule was much bigger than the seed. The size of the crystal grown was 30 × 20 × 60 mm^3. The obtained transparency for the crystal grown by SR method is 93% and by conventional method is 85% in the entire visible region. The HRXRD analysis indicates that the crystalline perfections of the crystals are excellent without having any very internal structural grain boundaries. The obtained FWHM for conventional method grown crystal is 12 arc s and for SR method is 6 arc s. Low dielectric loss indicates that the <0 01> directed crystal contains minimum defects. Higher mechanical stability was observed in SR method grown KDP compared to the other. Laser damage threshold value has been determined using Nd:YAG laser operating at 1064 nm. The optical transmission study and the powder SHG measurement show the suitability of the ingot for nonlinear optical applications.