CdS microspheres composed of nanocrystals and their photocatalytic activity.

Rengaraj, Selvaraj,Jee, Sun Hee,Venkataraj, Selvaraj,Kim, Younghun,Vijayalakshmi, Selvaraj,Repo, Eveliina,Koistinen, Arto,Sillanp??, Mika American Scientific Publishers 2011 Journal of Nanoscience and Nanotechnology Vol.11 No.3

<P>A simple and template-free solution phase synthesis method has been developed for the preparation of novel CdS hollow microspheres using cadmium nitrate and thioacetamide precursors. In this manuscript, we demonstrate that process parameters such as the reaction time, precursor ratio, and reaction temperature strongly influence the morphology of the final product. The synthesized products have been characterized by a variety of methods, including X-ray powder diffraction (XRD), Raman spectroscopy, high-resolution scanning electron microscopy (HR-SEM), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray diffraction (EDX) analysis, X-ray photoelectron spectroscopy (XPS), and UV-visible diffused reflectance spectroscopy (UV-DRS). XRD analysis confirmed the cubic structure of the CdS microspheres, which has also been further supported by Raman spectroscopy. The HR-SEM measurements revealed the spherical morphology of the CdS microspheres which has been evolved by the oriented aggregation of the primary CdS nanocrystals. The TEM measurements confirmed the hollow shell-like structure of the spheres; the formation of their hollow interiors can be explained by the Ostwald ripening mechanism. UV-DRS studies showed that the band gap of the CdS microspheres increased with increasing cadmium-nitrate-to-thioacetamide ratio. Furthermore, studies of photocatalytic activity revealed that the synthesized CdS hollow microspheres exhibit an excellent photocatalytic performance in rapidly degrading methyl tert-butyl ether (MTBE) in aqueous solution under visible-light illumination. These results suggest that CdS microspheres will be an interesting candidate for photocatalytic detoxification studies under visible light radiation.</P>

Embargo Nature of CuO-PANI Composite Against Corrosion of Mild Steel in Low pH Medium

Selvaraj, P. Kamatchi,Sivakumar, S.,Selvaraj, S. The Korean Electrochemical Society 2019 Journal of electrochemical science and technology Vol.10 No.2

Incorporation of CuO nanoparticles during the polymerization of aniline in the presence of ammonium peroxydisulphate as an oxidizing agent and sodium salt of dodecylbenzene sulphonic acid as dopant as well as surfactant yielded water soluble CuO-PANI composite. Comparison of recorded spectra like FTIR, XRD and SEM with reported one confirm the formation of the composite. Analysis by gravimetric method exposes that the synthesized composite is having resistivity against corrosion, with slight variation in efficiency on extending the time duration up to eight hours in strong acidic condition. OCP measurement, potentiodynamic polarization and EIS studies also confirms the suppression ability of composite against corrosion. Riskless working environment could be provided by the synthesized composite during industrial cleaning process.

Correlation between gray values of cone-beam computed tomograms and Hounsfield units of computed tomograms: A systematic review and meta-analysis

Selvaraj, Abirami,Jain, Ravindra Kumar,Nagi, Ravleen,Balasubramaniam, Arthi Korean Academy of Oral and Maxillofacial Radiology 2022 Imaging Science in Dentistry Vol.52 No.2

Purpose: The aim of this review was to systematically analyze the available literature on the correlation between the gray values (GVs) of cone-beam computed tomography (CBCT) and the Hounsfield units (HUs) of computed tomography (CT) for assessing bone mineral density. Materials and Methods: A literature search was carried out in PubMed, Cochrane Library, Google Scholar, Scopus, and LILACS for studies published through September 2021. In vitro, in vivo, and animal studies that analyzed the correlations GVs of CBCT and HUs of CT were included in this review. The review was prepared according to the PRISMA checklist for systematic reviews, and the risk of bias was assessed using the Quality Assessment of Diagnostic Accuracy Studies tool. A quantitative analysis was performed using a fixed-effects model. Results: The literature search identified a total of 5,955 studies, of which 14 studies were included for the qualitative analysis and 2 studies for the quantitative analysis. A positive correlation was observed between the GVs of CBCT and HUs of CT. Out of the 14 studies, 100% had low risks of bias for the domains of patient selection, index test, and reference standards, while 95% of studies had a low risk of bias for the domain of flow and timing. The fixed-effects meta-analysis performed for Pearson correlation coefficients between CBCT and CT showed a moderate positive correlation (r=0.669; 95% CI, 0.388 to 0.836; P<0.05). Conclusion: The available evidence showed a positive correlation between the GVs of CBCT and HUs of CT.

Stabilization of cryptomelane α-MnO₂ nanowires tunnels widths for enhanced electrochemical energy storage

Selvaraj, Aravindha Raja,Rajendiran, Rajmohan,Chinnadurai, Deviprasath,Rajendra Kumar, Gunasekaran,Kim, Hee-Je,Senthil, Karuppanan,Prabakar, Kandasamy Elsevier 2018 ELECTROCHIMICA ACTA Vol.283 No.-

<P><B>Abstract</B></P> <P>One dimensional manganese oxides with tunnel structures have attracted as an effective electrochemical energy storage material because of its efficient electrolyte/cation interfacial charge transports which enables improved pseudo capacitive performance. We have reported a simple one step hydrothermal technique to incorporate K<SUP>+</SUP> ions to maintain the tunnel width of cryptomelane α-MnO<SUB>2</SUB> nanowires during cycling performance. The effects of K<SUP>+</SUP> ions on the electrochemical performance is studied by tuning the phases of α-KMnO<SUB>2</SUB> nanowires to Mn<SUB>3</SUB>O<SUB>4</SUB> through an intermediate phase of Mn<SUB>2</SUB>O<SUB>3</SUB> by subsequent calcinations at various temperatures. K<SUP>+</SUP> ions doped α-MnO<SUB>2</SUB> nanowires exhibit a highest specific capacitance of 402 Fg<SUP>-1</SUP> at a current density of 1 Ag<SUP>-1</SUP> in 1 M Na<SUB>2</SUB>SO<SUB>4</SUB> electrolyte solution compared to Mn<SUB>2</SUB>O<SUB>3</SUB> and Mn<SUB>3</SUB>O<SUB>4</SUB>. The as synthesized α-KMnO<SUB>2</SUB> nanowires have a wider tunnel widths and enriched OH radical species and hence the electrolyte cations (Na<SUP>+</SUP>) penetrate the tunnels very easily resulting the polarization enhanced intercalation pseudo capacitance. The symmetric α-KMnO<SUB>2</SUB> nanowire supercapacitor device shows very high energy density (15.83 Wh kg<SUP>−1</SUP>), power density (128.35 W kg<SUP>−1</SUP>) and excellent cyclic stability with 88% retention of the initial capacitance after 3000 cycles.</P>

Rapid-Response and Highly Sensitive Boronate Derivative-Based Fluorescence Probe for Detecting H ₂ O ₂ in Living Cells

Selvaraj, Muthusamy,Rajalakshmi, Kanagaraj,Nam, Yun-Sik,Lee, Yeonhee,Kim, Byoung Chan,Pai, Sung Jin,Han, Sang Soo,Lee, Kang-Bong Hindawi 2019 Journal of analytical methods in chemistry Vol.2019 No.-

<P>Intracellular H<SUB>2</SUB>O<SUB>2</SUB> monitoring is important and has driven researchers to pursue advancements for the rapid identification of H<SUB>2</SUB>O<SUB>2</SUB>, since H<SUB>2</SUB>O<SUB>2</SUB> is short-lived in cell lines. An arylboronate derivative has been investigated as a chemospecific fluorescence recognition agent for H<SUB>2</SUB>O<SUB>2</SUB>. Triphenylimidazoleoxadiazolephenyl (TPIOP) boronate was contrived as a novel candidate for the rapid and sensitive recognition of H<SUB>2</SUB>O<SUB>2</SUB>. The probe was conjugated using the TPIOP functional group acting as an excellent fluorescent enhancer. The TPIOP group stimulated the polarization of C–B bond due to its extended <I>π</I>-conjugation, which included heteroatoms, and induced the production of rapid signal because of the highly polar C–B bond along with the corresponding boronate unit. While H<SUB>2</SUB>O<SUB>2</SUB> reacts with TPIOP boronate, its nucleophilic addition to the boron generates a charged tetrahedral boronate complex, and then the C–B bond migrates toward one of the electrophilic peroxide oxygen atoms. The resulting boronate ester is then hydrolyzed by water into a phenol, which significantly enhances fluorescence through aggregation-induced emission. The TPIOP boronate probe responded to H<SUB>2</SUB>O<SUB>2</SUB> rapidly, within 2 min, and exhibited high sensitivity with a limit of detection of 8 nM and a 1000-fold selectivity in the presence of other reactive oxygen species. Therefore, the developed TPIOP boronate chemodosimeter was successfully utilized to visualize and quantify intracellular H<SUB>2</SUB>O<SUB>2</SUB> from human breast cancer (MCF-7) cells, as well as gaseous and aqueous H<SUB>2</SUB>O<SUB>2</SUB> from environmental samples using Whatman paper strips coated with TPIOP boronate.</P>

Electrical and Thermal Characterization of Organic Varnish Filled with ZrO₂ Nano Filler Used in Electrical Machines

Selvaraj, D. Edison,Vijayaraj, R.,Sugumaran, C. Pugazhendhi The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.4

In the last decade it has been witnessed significant developments in the area of nano particles and nano scale fillers on electrical, thermal, and mechanical properties of polymeric materials such as resins, varnishes, enamel and bakelites. The electric and thermal properties were more important in the electrical equipments for both steady state and transient state conditions. This paper deals with the characterization of the electric and thermal properties of the pure varnish and zirconia (ZrO₂) filler mixed varnish. The electric properties such as dielectric loss (tan δ), dielectric constant (ε), dielectric strength and partial discharge voltage were analyzed and detailed for different samples. It was observed that zirconia nano filler mixed varnish has the superior dielectric and thermal properties when compared to those of standard varnish. It has shown that at power frequency the 1wt% nano composite sample has the higher permittivity value when compared to other samples. It has been examined that the 1wt% sample was having higher inception and extinction voltages when compared to other samples. It has been observed that 1wt% sample has higher dielectric strength when compared with other samples. There has been an improvement of thermal property by adding few weight percent of zirconia nano fillers. There was not much variation in glass transition among the nano mixed composites. The weight loss was improved at 1wt% of the zirconia nano fillers.

On-off-on relay fluorescence recognition of ferric and fluoride ions based on indicator displacement in living cells

Selvaraj, Muthusamy,Rajalakshmi, Kanagaraj,Nam, Yun-Sik,Lee, Yeonhee,Song, Jong-Won,Lee, Ho-Jin,Lee, Kang-Bong Elsevier 2019 Analytica Chimica Acta Vol.1066 No.-

<P><B>Abstract</B></P> <P>A new boronic acid derivative functionalized with a 4-(3-(4-(4,5-diphenyl-1H-imidazole-2-yl)phenyl)-1,2,4-oxadiazol-5-yl)phenyl (IOP) moiety was synthesized for use as a sequential “on-off-on”-type relay fluorescence probe for Fe<SUP>3+</SUP> ions and F<SUP>−</SUP> ions with high selectivity and sensitivity under physiological conditions. The introduction of Fe<SUP>3+</SUP> to IOP boronic acid (IOPBA) formed an Fe<SUP>3+</SUP> IOPBA complex, which led to quenching of the blue fluorescence intensity at 458 nm. The lowest-energy conformation of IOPBA was theoretically predicted to adopt an extended structure, and the Fe<SUP>3+</SUP> ion in the Fe<SUP>3+</SUP> IOPBA complex was coordinated to two phenyl groups to form a π-complex. Upon addition of F<SUP>−</SUP> to the Fe<SUP>3+</SUP> IOPBA complex, the original fluorescence was recovered due to formation of [FeF<SUB>6</SUB>]<SUP>3‒</SUP>, resulting in “on-off-on”-type sensor behavior. IOPBA showed high selectivity towards Fe<SUP>3+</SUP> among other cations. Moreover, the Fe<SUP>3+</SUP> IOPBA complex showed specific selectivity towards F<SUP>−</SUP>, with other cations and anions not interfering with detection. Both sensing processes showed 1:1 stoichiometry with binding constants of 6.87 × 10<SUP>6</SUP> and 4.49 × 10<SUP>6</SUP> mol<SUP>−1</SUP> L for Fe<SUP>3+</SUP> with IOPBA and F<SUP>−</SUP> with Fe<SUP>3+</SUP> IOPBA, respectively. The limits of detection for Fe<SUP>3+</SUP> and F<SUP>−</SUP> were 10 and 1 nM, respectively. The proposed method was successfully applied in real water samples. Furthermore, the probe had low cytotoxicity and was successfully used as a bioimaging reagent to detect intracellular Fe<SUP>3+</SUP> and F<SUP>−</SUP> in living HeLa cells.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Imidazole oxadiazole boronic acid derivative (IOPBA) was designed and synthesized. </LI> <LI> IOPBA showed highly sensitive and selective response for Fe<SUP>3+</SUP> and F<SUP> <B>−</B> </SUP>. </LI> <LI> On-off-on type relay response was achieved at Fe<SUP>3+</SUP> IOPBA with F<SUP> <B>−</B> </SUP>. </LI> <LI> The probe expressed LODs of 10 and 1 nM for Fe<SUP>3+</SUP> and F<SUP>−</SUP>, respectively. </LI> <LI> IOPBA can be utilized as bioimaging reagent for Fe<SUP>3+</SUP> and F<SUP>−</SUP> in living HeLa cells. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Antibacterial and anticoagulant activity of silver nanoparticles synthesised from a novel source–pods of Peltophorum pterocarpum

Selvaraj Raja,Vinayagam Ramesh,Varadavenkatesan Thivaharan 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.29 No.-

We report the ability of a novel source – the aqueous extract of pods of Peltophorum pterocarpum for thesynthesis of silver nanoparticles (SNPs). SEM analysis exposes the spherical shape of the nanoparticlesand UV–vis spectra show the surface plasmon resonance peak at 407 nm. XRD analysis showed thecrystalline nature of SNPs. FT-IR spectra show the presence of biomolecules which play a role ofreduction of AgNO3 and capping the formed SNPs. A negative zeta potential of 15.8 mV endorses thestability and dispersion of SNPs. The antibacterial activity of the SNPs was demonstrated againstEscherichia coli and anticoagulant activity was also revealed

Isoxazoline, Isoxazole, and Oxadiazole Derivatives as M1 Muscarinic Acetylcholine Receptor Agonists

Selvaraj Muthusamy,이수민,Minghua Huang,Nam-Chul Cho,남길수,Ae Nim Pae,Hyewhon Rhim,금교창,최경일 대한화학회 2016 Bulletin of the Korean Chemical Society Vol.37 No.7

Insertion of a methylene linker between the 2-pyrrolidinone substituent and the isoxazoline core of the lead compound 1 previously reported resulted in the loss of its agonistic activity. One exception was the compound 6f having oxadiazole core and 2-azabicyclo[2.2.1]heptane substituent. Of the two isomers of 6f, exo-isomer (EC50 0.013 μM) was five- to six-fold more effective than endo-isomer (EC50 0.30 μM), and ca. two-fold active than the mother compound 1 (EC50 0.031 μM) in stimulating the M1 mAChR. Both isomers were moderately selective agonists for M1 mAChR over the rest four subtypes, and it could be explained by docking study on active conformation allosteric binding sites of M1–M5 mAChRs and calculating their binding energies.

Batch Adsorptive Removal of Copper Ions in Aqueous Solutions by Ion Exchange Resins: 1200H and IRN97H

Selvaraj Rengaraj,최경희,이종협,김영훈,Cheol Kyun Joo 한국화학공학회 2004 Korean Journal of Chemical Engineering Vol.21 No.1

The removal of copper from aqueous solution by ion exchange resins, such as 1200H and IRN97H, is described. Effect of initial metal ion concentration, agitation time and pH on adsorption capacities of ion exchange resins was investigated in a batch mode. The adsorption process, which is pH dependent, shows maximum removal of copper in the pH range 2-7 for an initial copper concentration of 10 mg/L. The experimental data have been analyzed by using the Freundlich, Langmuir, Redlich-Peterson, Temkin and Dubinin-Radushkevich isotherm models. The batch sorption kinetics have been tested for a first-order, pseudo-first order and pseudo-second order kinetic reaction models. The rate constants of adsorption for all these kinetic models have been calculated. Results showed that the intraparticle diffusion and initial sorption into resins of Cu(II) in the ion exchange resins was the main rate limiting step. The uptake of copper by the ion exchange resins was reversible and thus has good potential for the removal/recovery of copper from aqueous solutions. We conclude that such ion exchange resins can be used for the efficient removal of copper from water and wastewater.