Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Centre for Nanotechnology Research

Traditionally used fluorescent powders for developing invisible (latent) fingerprints involve complicated operation and show characteristics of auto-fluorescence interference and high toxicity. To overcome these serious drawbacks we report a novel application and facile methodology to extract high contrast fingerprints on non-porous and porous substrates using a chemically inert, visible light excitable, and nanosized SrAl2O4:Eu2+,Dy3+ phosphorescent label in the dark. The chemistry of non-covalent physisorption interaction between the long afterglow phosphor powder and sweat residue in fingerprints has been discussed in detail. Real-time fingerprint development on porous and non-porous substrates has also been performed. © 2018 The Royal Society of Chemistry.

Vellore Campus

World University root node

Fulltext

Analytical Methods

Chemistry of extracting high-contrast invisible fingerprints from transparent and colored substrates using a novel phosphorescent label

Europium (Eu) doped LiF crystals have been grown by the Edge-defined film fed growth (EFG) technique. The designing and installation of the furnace used for the growth of the crystals have been discussed in detail. In the present study, Eu (Eu2O3) has been doped in LiF in different concentration (0.02–0.2 wt %). X-ray diffractometry (XRD) and Energy Dispersive X-ray (EDX) spectroscopy confirms the incorporation of Eu in LiF. The influence of Eu on LiF has been investigated through photoluminescence (PL), thermoluminescence (TL) and electron paramagnetic resonance (EPR) in as-grown and annealed crystals. PL emission spectra shows the presence of both Eu3+ and Eu2+ form in the as-grown crystals which is confirmed by EPR results. Whereas, in annealed crystals, Eu is present predominantly as Eu2+ form. This suggests that growing crystals at high temperature (∼900 °C) in argon gas atmosphere through EFG technique favours the reduction of Eu3+ → Eu2+. This reduction phenomenon has been explained on the basis of charge compensation model. TL study of the LiF: Eu (0.02–0.2 wt %) crystals has been done after irradiation with Co60 gamma rays. In this study, it has been observed that the TL intensity as well as glow curve structure of LiF: Eu crystals are a strong function of Eu concentration. The maximum TL is observed at Eu concentration of 0.05 wt% at which a well defined glow curve structure with a prominent peak at 185 °C and a small peak at 253 °C. Beyond this concentration (0.05 wt %), TL intensity decreases due to aggregation of defects in the host. The peak at 185 °C in LiF: Eu (0.05 wt %) is certainly due to the presence of Eu2+ associated defects which is also supported by the PL spectra. It has been observed that Eu doping have a key role in creation of more defect levels which lead to the increased number of electron and hole traps. Further, trapping parameters are analysed using glow curve deconvolution method to have an insight study of TL phenomena. Further, TL glow curve structure of as-grown and annealed crystal are distinct which may be attributed to the nature of defect traps formed inside the LiF. © 2018 Elsevier Ltd

Journal of Physics and Chemistry of Solids

A photoluminescence, thermoluminescence and electron paramagnetic resonance study of EFG grown europium doped lithium fluoride (LiF) crystals

In this study the interaction mechanism between newly synthesized 4-(3-acetyl-5-(acetylamino)-2-methyl-2, 3-dihydro-1,3,4-thiadiazole-2-yl) phenyl benzoate (thiadiazole derivative) anticancer active drug with calf thymus DNA was investigated by using various optical spectroscopy techniques along with computational technique. The absorption spectrum shows a clear shift in the lower wavelength region, which may be due to strong hypochromic effect in the ctDNA and the drug. The results of steady state fluorescence spectroscopy show that there is static quenching occurring while increasing the thiadiazole drug concentration in the ethidium bromide-ctDNA system. Also the binding constant (K), thermo dynamical parameters of enthalpy change (ΔH°), entropy change (ΔS°) Gibbs free energy change (ΔG°) were calculated at different temperature (293 K, 298 K) and the results are in good agreement with theoretically calculated MMGBSA binding analysis. Time resolved emission spectroscopy analysis clearly explains the thiadiazole derivative competitive intercalation in the ethidium bromide-ctDNA system. Further, molecular docking studies was carried out to understand the hydrogen bonding and hydrophobic interaction between ctDNA and thiadiazole derivative molecule. In addition the docking and molecular dynamics charge distribution analysis was done to understand the internal stability of thiadiazole derivative drug binding sites of ctDNA. The global reactivity of thiadiazole derivative such as electronegativity, electrophilicity and chemical hardness has been calculated. Copyright © 2018 John Wiley & Sons, Ltd.

Luminescence

A cytotoxicity, optical spectroscopy and computational binding analysis of 4-[3-acetyl-5-(acetylamino)-2-methyl-2,3-dihydro-1,3,4-thiadiazole-2-yl]phenyl benzoate in calf thymus DNA

We report a simple PEG-600 assisted solvothermal method for the synthesis iron ferrite with functionalized multi-walled carbon nanotube (Fe3O4/fMWCNT) composite nanoassemblies. The results show that the composite deliver excellent electrochemical activity because of the synergistic effect of each component. The fMWCNT act as a conductive network with high surface area promoting fast movement of electrons which enhances the charge storing nature and stability of Fe3O4 nanoassemblies. © 2018 Author(s).

VIT Unitversity

AIP Conference Proceedings

Enhanced supercapacitive behaviour of Fe3O4/fMWCNT nanoassemblies synthesized by PEG-600 assisted solvothermal method

We report synthesis of highly luminescent and n-type conducting aluminium doped ZnO (AZO) phosphors using flux-free solid-state reaction technique followed by casting of thin films. The precursor powders were pelletized and fired at 1000°C (AZO-1). In another typical case,2-stage sequential firing has been adapted at 1000°C followed by 1200°C (AZO-2) in a flowing O2 gas environment. The stabilization (dwell) time has been fixed as 2 hours for all temperatures of firing in the furnace. After firing at 1200°C, a new cubic phase (zinc aluminate) has been observed in the lattice along with the wurtzite ZnO phase. The microstructure analysis was substantiated with Rietveld refinement of the diffraction data of AZO-1 and AZO-2 samples. The photoluminescence (PL) measurements revealed that both AZO-1 and AZO-2 exhibited green (∼523 nm) PL under UV (375 nm) excitation, with emission intensity of AZO-1 comparatively higher than that of AZO-2 sample. Moreover, the measurement of electronic transport properties of the AZO-1 and AZO-2 samples exposed their n-type behavior, with slightly lower electrical resistivity of AZO-1 (4.7 x 10-3Ω-m) as compared to AZO-2 (3 x 10-3Ω-m) at 700 K temperature. The AZO samples have been used as target materials for transparent thin film deposition on quartz substrate, thus proving it to be ideal materials for solar cell applications. © 2017 Elsevier Ltd.

Materials Today: Proceedings

Structural, morphological, photoluminescence and electrical characterization of aluminium doped ZnO phosphors for solar cell applications

This work reports on the development of thin films of SnO2 doped with cerium and palladium and shows them to be viable materials for chemoresistive sensing of hydrogen (H2). The sensing material was synthesized by a hydrothermal route and with different weight percentage loadings of the dopants. The structural and morphological features were investigated by X-ray diffraction, field emission scanning electron microscopy, FTIR and X-ray photoelectron spectroscopy. Thin films were fabricated by spin coating on a ceramic substrate. The change in the resistance of the film was measured as a function of the concentration of H2. The results show that the amount of loading with Ce and Pd has a large effect on the performance. The Ce doped nanocomposite sensor has a lower detection limit of 50 ppm of H2 and covers the 50 to 500 ppm H2 concentration range if operated at the optimum temperature of 200 °C and a working voltage of 5 V. [Figure not available: see fulltext.]. © 2017, Springer-Verlag GmbH Austria.

Department of Bio-Sciences

School of Bio Sciences and Technology

Microchimica Acta

Chemoresistive sensor for hydrogen using thin films of tin dioxide doped with cerium and palladium

In this study, cobalt ferrites (C) decorated onto 2D material (porous graphene (PG)) and 1D material (carbon nanofibers (CNF)), denoted as PG-C and CNF-C nanocomposites, respectively, were synthesized using solvothermal process. The prepared nanocomposites were studied as magnetic adsorbents for the removal of lead (cationic) and chromium(VI) (anionic) metal ions. The structural and chemical analysis of synthesized nanocomposites was conducted using different characterization techniques including Brunauer-Emmett-Teller (BET) analysis, field emission-scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FTIR), high resolution-transmission electron microscopy (HR-TEM), vibrating sample magnetometer (VSM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Batch mode adsorption studies were conducted with the prepared nanocomposites to examine their maximum adsorption potential for lead and chromate ions. Performance parameters (time, pH, adsorbent dosage and initial ion concentrations) effecting the adsorption capacity of the nanocomposites were optimized. Different kinetic and isotherm models were examined to elucidate the adsorption process. Synthesized nanocomposites exhibited significant potential for the studied metal ions that can be further examined at pilot scale for the removal of metal ions from contaminated water. © 2017 The Author(s).

Scientific Reports

Removal of cationic and anionic heavy metals from water by 1D and 2D-carbon structures decorated with magnetic nanoparticles

The crystal structures of mono- and dinuclear CuII trifluoromethanesulfonate (triflate) complexes with benzyldipicolylamine (BDPA) are described. From equimolar amounts of Cu(triflate)2 and BDPA, a water-bound CuII mononuclear complex, aqua(benzyldipicolylamine-κ3 N,N′,N′′)bis(trifluoromethanesulfonato-κO)copper(II) tetrahydrofuran monosolvate, [Cu(CF3SO3)2(C19H19 N3)(H2O)]·C4H8O, (I), and a triflate-bridged CuII dinuclear complex, bis(μ-trifluoromethanesulfonato-κ2 O:O ′)bis[(benzyldipicolylamine-κ3 N,N′,N′′)(trifluoromethanesulfonato-κO)copper(II)], [Cu2(CF3SO3)4(C19H19N3)2], were synthesized. The presence of residual moisture in the reaction medium afforded water-bound complex (I), whereas dinuclear complex (II) was synthesized from an anhydrous reaction medium. Single-crystal X-ray structure analysis reveals that the CuII centres adopt slightly distorted octahedral geometries in both complexes. The metal-bound water molecule in (I) is involved in intermolecular O—H...O hydrogen bonds with triflate ligands and tetrahydrofuran solvent molecules. In (II), weak intermolecular C—H...F(triflate) and C—H...O(triflate) hydrogen bonds stabilize the crystal lattice. Complexes (I) and (II) were also characterized fully using FT–IR and UV–Vis spectroscopy, cyclic voltammetry and elemental analysis.