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Herein, we present defect-induced photoluminescence behavior of Ga-doped ZnO (GZO) thin films with varying doping (Ga) concentrations and energetic ion irradiation. The Ga-doped ZnO thin films were prepared by a sol-gel spin-coating method. Micro-photoluminescence (μ-PL) was carried out to investigate the defect-related emission with the variation of doping concentration and ion irradiation. The PL spectra revealed that all films showed near-band-edge (NBE) emission along with a broad visible emission band, consisting of violet, blue, green, and yellow emission bands. The intensity of these emission bands was found to be strongly dependent on the Ga doping concentration and ion irradiation. Interestingly, a pronounced violet emission band around 2.99 eV (415 nm) was observed for the Ga-doped ZnO thin films with high Ga doping concentration, whereas an irradiated film with high ion fluence exhibited a strong green emission around 2.39 eV (519 nm); however, we concluded that the violet emission might have originated from zinc interstitial defects (Zni), and the concentration of Zni increased with the increasing doping concentration. The green emission is ascribed to the oxygen vacancies (VO), and the concentration of the VO defects increases with the increasing ion fluence. Thus, the μ-PL spectra of the irradiated films with emission dominating in the blue and green regions could be attributed to the formation of extended defects such as clusters and ionizing centers of Zni and VO. Herein, an in-depth understanding of the variation in defects related to the emission bands from these films is reported and correlated with the transport properties of these films for their possible optoelectronic applications.

$\mathrm{NdGa}{\mathrm{O}}_{3}$ (NGO) is an important substrate material often used in depositing functional oxide thin films. We have carried out temperature-dependent polarized Raman and infrared spectroscopy studies along with theoretical calculations on single-crystal NGO, which revealed a structural phase transition from centrosymmetric space group Pbnm to noncentrosymmetric space group $Pbn{2}_{1}$ at \ensuremath{\sim}200 K. The microscopic origin of the phase transition is extracted using a unique protocol involving polarized Raman spectroscopy (PRS) studies carried out as a function of crystallographic orientation. Here, we demonstrate the power of PRS in probing directional atomic rearrangements across the phase transition.

The CrVO4 and reduced graphene oxide (rGO)–CrVO4 composite has been synthesized through solid-state reaction and modified Hummer method and ultrasonication-assisted solid-state reaction method, respectively. The structural, compositional, and morphological features were studied by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy techniques. The Raman spectroscopy shows the indicative GO, and CrVO4 peaks, respectively, and the coexistence of these peaks in composite material. The photocatalytic activity of rGO–CrVO4 composite evaluated by photocatalytic degradation of methylene blue dye under UV-light irradiation shows improved ability for composite as compared to the parent compound CrVO4. The rate constant evaluated for rGO–CrVO4 is 6.7 × 10–2 min–1. Electrochemical characterization through cyclic voltammetry, galvanostatic charging and discharging, and impedance analysis was carried out. The rGO–CrVO4 composite exhibits a higher specific capacitan...

In this work, we report the distribution ratios of Zr(IV), Co(II), Sb(V) and Nb(V) using polyaniline in HCl, HF, oxalic acid and HF + HCl solutions. Distribution ratios were determined by batch method using radiotracer technique. Further, the separation factors and the %-uptake of metal ions were calculated and compared. Among the media studied, separation factors for Co(II), Sb(V) and Nb(V) with respect to Zr(IV) were the highest in 1 M HCl and the values are 52, 108 and 404 respectively. The results of this study can be utilized for designing an ion-exchange process for the decontamination of zircaloy pressure tubes used in the Pressurized Heavy Water Reactors.

Journal of alloys and compounds 749, 768 - 775 (2018). doi:10.1016/j.jallcom.2018.03.261, This paper demonstrates fine size-controlled synthesis of superparamagnetic carbon-encapsulated iron nanoparticles, by a supersonic plasma jet assisted rapid, bulk-production process, by manipulation of the pressure in the sample collection chamber. Transmission electron microscopy and small angle x-ray scattering measurements confirmed the formation of single-crystals with a narrow size distribution, having core average size of 5.0 nm and encapsulated by an ultrathin carbon coating, for sub-mbar pressure. VSM and Mossbauer characterization established the nanocrystallites to be superparamagnetic in nature, with saturation magnetization 67 emu/g and coercive field 7.4 Oe. Controlled plasma heating during synthesis led to the burning down of extra carbon that resulted in further enhancement of the magnetization of the product. Graphitization of the encapsulating layers also enhanced, which could successfully protect the metallic core from oxidation, as well as improved its cyto-compatibility. This purified sample could be ideal for targeted drugs delivery and water treatment applications. Another sample was processed through controlled reaction with oxygen, the as-synthesized sample having magnetic properties approaching that of the first sample, which may be more attractive especially for water treatment processes because of the simpler single-step processing of the material., Published by ScienceDirect, Amsterdam [u.a.]

The mango fruits remain biologically active even after harvest as they continue respiration, transpiration and other bio-chemical processes. Being highly perishable, the fruit quality deteriorates fast under ambient conditions (30 ± 5 °C and 50 ± 5% RH), rendering them unmarketable within 5–6 days. In order to extend the shelf-life of ‘Amrapali’ mango fruits, we have treated them with three different concentrations (500, 750 and 1000 ppb) of 1-Methylcyclopropene (1-MCP) @ 20 °C and stored at ambient conditions. Among all the treatments, 1000 ppb was found to be an effective in extending shelf-life till twelfth day with minimum physiological loss in weight (19.24%), maximum firmness (10.43 N), highest retention of quality parameters such as soluble solid concentrates (27.88 °B), ascorbic acid (28.49 mg 100 g−1 FW) and total antioxidant activity (675.41 µmol Trolox g−1 FW) compared to untreated mango fruits (21.79%, 5.45 N, 23.17 °B, 19.55 mg 100 g−1 FW and 265.41 µmol Trolox g−1 FW, respectively). Gene expression studies have revealed that the texture related gene expansin was significantly repressed till fifth day of storage with increasing concentrations of 1-MCP.

Commiphora wightii is an endangered tree valued for its gum guggul-resin that has cholesterol-reducing activity is well documented in alternative systems of medicine. Phytochemical investigations were taken up in six accessions of C. wightii and micropropagation protocol developed for its conservation. The leaves and gum of C. wightii were qualitatively and quantitatively tested for secondary metabolites and an elite accession with very high contents of total sterols and phenols was identified. An efficient HPLC method was utilized in the present study to estimate the valuable and pharmaceutically important steroid compounds present in its gum, viz. E-Guggulsterone and Z-Guggulsterone, which are hypolipidemic agents. The estimation resulted in the values of 2.45 mg/L and 2.17 mg/L for E- and Z -guggulsterone respectively. A highly efficient micropropagation protocol with good rooting and a high plantlet survival was developed from the nodal explants to aid its conservation and 360 plants survived out of 396 plants (transferred to the field) with a high percentage of survival (92.8%). The micropropagation efficiency reported presently in C. wightii far exceeds all the earlier reports and was mainly achieved due to strong rooting and healthier state of plantlets.

The paper presents synthesis of (1-x)PMN-(x)PT (PMN-PT) near morphotropic phase boundary (MPB) i.e. for x = 0.25, 0.31, 0.33 and 0.35, using hydroxide co-precipitation method. Further, PMN-PT compositions under investigation were systematically characterized for density, structural, morphological, dielectric and ferroelectric properties. X-ray diffraction data reveals single phase formation of PMN-PT. The scanning electron microscopy (SEM) images were recorded and used to understand morphology of the samples. In present study, it was noted that the PMN-PT composition with x = 0.25 exhibits the maximum value of dielectric constant (ϵ) and saturation polarization (Pmax) amongst the PMN-PT compositions under investigation.

Solvent extraction studies on protactinium were carried out from hydrofluoric acid, hydrochloric acid, and a mixture of hydrochloric and hydrofluoric acids using Aliquat 336 and 231Pa. The extraction of protactinium from hydrofluoric acid (0.025–10 M) decreased with increasing acid concentration and was less than 10% above 5 M. The extraction from hydrochloric acid (0.5–8 M) started only above 4 M and increased with increasing acid concentration. The extraction of protactinium from a mixture containing hydrochloric acid (0.5–8 M) and 0.03 M hydrofluoric acid decreased with increasing acid concentration reached to a minimum at about 2 M and then increased with increasing acid concentration. At low acidity, extraction of protactinium from hydrofluoric acid was higher compared to hydrochloric acid and the mixture of hydrochloric and hydrofluoric acids. Nitric acid (10 M) and hydrofluoric acid (10 M) were suitable for quantitative recovery of protactinium from organic phase. The extraction of 231Pa fr...

Interaction behavior of uranyl nitrate hexahydrate (UNH) and lanthanum nitrate hexahydrate (LaNH) have been investigated on the mixtures in different molar ratios of the two precursors and monitoring the reactions at elevated temperatures with thermoanalytical and X-ray diffraction measurement techniques. During the decomposition of equimolar mixture of LaNH and UNH, formation of lanthanum uranate (U 0.5 La 0.5 )O 2 , was seen by the temperature of 500 °C along with lanthanum oxide (La 2 O 3 ) and uranium trioxide (UO 3 ). By the temperature of 700 °C, the formation of uranium sesquioxide (U 3 O 8 ) was observed along with (U 0.5 La 0.5 )O 2 as end products in uranium rich mixtures. Lanthanum rich compositions decomposed by the temperature of 700 °C to give (U 0.5 La 0.5 )O 2 and La 2 O 3 as end products.

Hyperfine interactions 240(1), 99 (2019). doi:10.1007/s10751-019-1633-4, We studied the structural and magnetic properties of in-situ grown iron mononitride (FeN) thin films. Initial stages of film growth were trapped utilizing synchrotron based soft x-ray absorption near edge spectroscopy (XANES) at the N K-edge and nuclear resonant scattering (NRS). Films were grown using dc-magnetron sputtering, separately at the experimental stations of SXAS beamline (BL01, Indus 2) and NRS beamline (P01, Petra III). It was found that the initial stages of film growth differs from the bulk of it. Ultrathin FeN films, exhibited larger energy separation between the $t_{2g}$ and $e_g$ features and an intense eg feature in the N K-edge pattern. This indicates that a structural transition is taking place from the rock-salt (RS)-type FeN to zinc-blende (ZB)-type FeN when the thickness of films increases beyond 5nm. The behavior of such N K-edge features correlates very well with the emergence of a magnetic component appearing in the NRS pattern at 100K in ultrathin FeN films. Combining the in-situ XANES and NRS measurements, it appears that initial FeN layers grow in a RS-type structure having a magnetic ground state. Subsequently, the structure changes to ZB-type which is known to be non-magnetic. Observed results help in resolving the long standing debate about the structure and the magnetic ground state of FeN., Published by Springer Science + Business Media B.V, Dordrecht [u.a.]

A variety of bis(azolyl) urea derivatives were prepared by the reaction of methyl benzazoyl carbamates with azolyl amines in the presence of mild base and studied their antimicrobial activity. The presence of electron donating substituents on the aromatic ring enhanced the activity. Methoxy substituted benzothiazolyl thiazolyl urea, benzothiazolyl imidazolyl urea and benzimidazolyl thiazolyl urea displayed prominent antibacterial activity against Bacillus subtilis. Benzothiazolyl imidazolyl urea and methyl substituted benzimidazolyl imidazolyl urea showed good antifungal activity against Aspergillus niger. © 2019 Author(s).

Keeping in mind the immense biological potential of chalcones and sulfonamide scaffolds, a library of sulfonamide chalcones has been synthesized and evaluated for in vitro antifilarial assay against human lymphatic filarial parasite Brugia malayi. Experimental evidence showcased for the first time the potential of some sulfonamide chalcones as effective and safe antifilarial lead molecules against human lymphatic filarial parasite B. malayi. Sulfonamide chalcones 4d, 4p, 4q, 4t and 4aa displayed the significantly wide therapeutic window. Particularly chalcones with halogen substitution in aromatic ring proved to be potent antifilarial agents against Brugia malayi. Sulphonamide chalcones with lipophilic methyl moiety (4q and 4aa) at para position of terminal phenyl rings of compounds were found to have remarkable antifilarial activities with therapeutic efficacy. Observed preliminary evidence of apoptosis by effective chalcone derivatives envisaged its fair possibility to inhibit folate pathway with consequent defect in DNA synthesis.

A reduced graphene oxide–gold nanoparticle composite was synthesized and characterized by the X-ray diffraction and microscopy. Modified carbon paste electrode was fabricated from the film of the composite. Adsorption of melamine on the composite material was characterized by scanning electrochemical microscopy. Melamine was determined by probing the decrease in the oxidation of ferrocyanide on the modified carbon paste electrode. An analytical method for the determination of melamine has been proposed using the modified electrode. The detection limit of the method was 2.23 µM.

Phase-change materials (PCM) show remarkable property-contrast from amorphous to crystalline phase that forms the basis for high-speed non-volatile memory device applications. Despite understanding the local structure and physical properties of these phases, a systematic study on the phase-change behavior is essential. Here, we used in situ UV–Vis–NIR spectroscopic measurements to study a systematic evolution of optical band gap (Eg) and the local disorder described by Tauc parameter (B), for the temperatures from 90 to 480 K on amorphous and cubic phases of Ge1Sb4Te7 thin films. It has been found that the Eg of amorphous phase decreases with increasing temperature from 90 to 400 K, while the disorder as exemplified by B, increases owing to thermal vibrations. At 420 K, a rapid decrease in the Eg from 0.47 to 0.33 eV and also a sharp reduction of ∼13% in the value of B1/2 is observed evidencing the signature of amorphous-to-cubic phase transition. Furthermore, the hexagonal phase is more disordered compared to cubic phase. The Raman results are consistent with optical measurements, which indicate that the degree of disorder reduces from amorphous to cubic phase, while hexagonal phase with an increased disorder is attributed to elongated bonds.

Hg(II) was sorbed on polyaniline from aqueous solutions, followed by determination using energy dispersive X-ray fluorescence spectrometry. Distribution coefficient of Hg(II) on polyaniline was about 4 × 103 in water, whereas distribution coefficient was 1.2 × 104 at 0.1 M HCl and decreased drastically with increase in HCl concentration. Rapid kinetics of sorption was evinced by the 80% uptake within the initial 1 min and quantitative sorption within 5 min of equilibration. The sorption was found to follow Langmuir isotherm model, and the Langmuir capacity was calculated as 19.7 mg g−1. The ability of polyaniline to form stable and homogeneous pellets facilitated the energy dispersive X-ray fluorescence determination without recourse to elution. Detection limit of Hg was found to be 22 ng, considering 100 mg pellet of polyaniline. The apparent detection limit was 6 pg, as the preconcentration factor of Hg(II) on polyaniline was 4 × 103. The developed method is at par with the established method for mercury determination, namely, cold vapor atomic absorption spectrometry. Accuracy of the method was established by the analysis of the International Atomic Energy Agency reference materials, namely, hair and lichen, for Hg(II). Copyright © 2016 John Wiley & Sons, Ltd.

The present manuscript reports vibrational spectra and optical studies of polycrystalline Fe1-xCrxVO4 solid solutions through FT-IR spectroscopy augmented with a group theory (G.T.) analysis and UV-Visible DRS spectroscopy. Full set of IR and Raman modes are determined by G. T. for various crystal symmetries in FeVO4-CrVO4 solid solutions where Triclinic, Monoclinic and Orthorhombic structures evolve with increasing Cr concentration. Experimentally obtained vibrational modes support the structural phase transitions and confirm formation of continuous solid solutions in Fe1-xCrxVO4. The Diffuse Reflectance Spectra (DRS) of Fe1-xCrxVO4 depicts the electronic structure and different optical transitions due to absorption of photon energy. The d-d transitions are manifested for all compounds in terms of crystal field stabilization energy (CFSE) caused by distorted lattice sites. The band gap energy of Fe1-xCrxVO4 is calculated using Tauc formula. It shows a red shift initially within triclinic structure then blue shift with the increase of Cr concentration. Urbach energy (Eu) tails in the spectra show the electronic structural disorder in Fe1-xCrxVO4 due to impurity energy levels of Cr ions within band gap region. It is observed that Eu decreases with the doping concentration due to the increase in crystal symmetry corresponding to the structural phase transitions in Fe1-xCrxVO4.

Thermal stability of polyaniline was evaluated to assess its use as ion-exchanger at elevated temperatures. Thermogravimetric analysis of salt (chloride) and base form of polyaniline revealed the decomposition pattern and volatile products. Structural modifications in PAni upon heating upto 500 °C were studied using UV–vis spectroscopy, Fourier Transform Infrared spectroscopy, and viscometry. The gaseous decomposition products of polyaniline were identified using high resolution infrared spectroscopy for the first time. Anion exchange capacity of polyaniline, in terms of ionizable chlorine, determined using Energy Dispersive X-ray Fluorescence spectrometry, was found to be 3.25 meq g −1 . Polyaniline was found to retain ∼90% of the original capacity on heating upto 200 °C. These studies evinced the superior thermal stability of polyaniline over conventional anion exchangers.

Sapindus saponaria bark powder (SSBP), an agro-waste material was investigated as a biosorbent for the removal and recovery of Cu(II) from aqueous solution. This biosorbent was characterized by infrared spectroscopy, X-ray diffraction, scanning electron microscopy and elemental analysis. The influence of various parameters such as effect of initial pH, contact time, metal ion concentration and sorbent dose on the removal of Cu(II) was investigated using batch process. Langmuir, Freundlich and Dubinin–Radushkevich isotherm models were applied to describe the adsorption isotherms. The Langmuir model fitted the equilibrium data better than the other isotherm models. The maximum adsorption capacity of Cu(II) was calculated from the Langmuir isotherm and found to be 37.09 mg g−1 at pH 5.0. The kinetic studies revealed that the biosorption of Cu(II) onto SSBP followed the pseudo-second-order rate model. Evaluated thermodynamic parameters, ∆G°, ∆H° and ∆S°, showed that the biosorption of Cu(II) onto SSBP...

A variety of symmetrical trisheterocycles bis-oxazolyl/thiazolyl/imidazolylacetamido-sulfonylmethyl 1,3,4-oxadiazoles and 1,3,4-thiadiazoles was prepared, and their antioxidant activity was studied. The compounds bisoxazolyl oxadiazole and bisoxazolyl thiadiazole having methyl substituent on the aromatic ring exhibited greater antioxidant activity than the standard ascorbic acid.

Silver/tungsten oxide multi-layer films are deposited over quartz substrates by RF magnetron sputtering technique and the films are annealed at temperatures 200, 400 and 600 °C. The effect of thermal annealing on the phase evolution of silver tungstate phase in Ag/WO 3 films is studied extensively using techniques like X-ray diffraction, micro-Raman analysis, atomic force microscopy and photoluminescence studies. The XRD pattern of the as-deposited film shows only the peaks of cubic phase of silver. The film annealed at 200 °C shows the presence of XRD peaks corresponding to orthorhombic phase of Ag 2 WO 4 and peaks corresponding to cubic phase of silver with reduced intensity. It is found that, as annealing temperature increases, the volume fraction of Ag decreases and that of Ag 2 WO 4 phase increases and becomes highest at a temperature of 400 °C. When the temperature increases beyond 400 °C, the volume fraction of Ag 2 WO 4 decreases, due to its decomposition into silver and oxygen deficient phase Ag 2 W 4 O 13 . The micro-Raman spectra of the annealed films show the characteristic bands of tungstate phase which is in agreement with XRD analysis. The surface morphology of the films studied by atomic force microscopy reveals that the particle size and r.m.s roughness are highest for the sample annealed at 400 °C. In the photoluminescence study, the films with silver tungstate phase show an emission peak in blue region centered around the wavelength 441 nm (excitation wavelength 256 nm).

A color changeable cellulose triacetate (CTA) membrane-based optode has been developed for the highly selective and sensitive determination of Hg(II) ions in aqueous solutions. The sensing layer of the optode consists of phenylthiosemicarbazide derivative of rhodamine 6G immobilized in a plasticized CTA membrane. The colorless optode film on reaction with Hg(II) turned pink, in color, and the intensity of the color was found to be directly proportional to the amount of Hg(II). The sensing mechanism is based on the mercury-induced spirolactum ring opening followed by its cyclization to form highly conjugated system which leads to the development of pink color. Various experimental parameters such as pH, optode composition and response time have been optimized. Under these conditions, the sensor showed a wide linear dynamic range of 10–5000 ng mL−1 Hg(II), with a detection limit of 1.3 ng mL−1. In addition to its stability and reproducibility, optode showed a high selectivity toward Hg(II) ions as compared to other coexisting ions in real water samples. The developed optode is suitable for rapid and onsite detection of Hg(II) ions in a variety of aqueous samples. The sensor was successfully applied for the determination of Hg(II) ions in groundwater samples.

Thermal and X-ray diffraction measurements have been used to study the formation of various nitrato-complexes as intermediates and mixed oxides as end products using different mol ratios of the ternary mixtures of UO 2 (NO 3 ) 2 ⋅6H 2 O, NaNO 3 and Sr(NO 3 ) 2 at high temperatures. These results indicate the interaction of UO 2 (NO 3 ) 2 ⋅6H 2 O and NaNO 3 in equimolar ratio to form sodium uranyl nitrate monohydrate (Na[UO 2 (NO 3 ) 3 ]⋅H 2 O), dimerized sodium uranyl oxynitrate (Na 2 [(UO 2 NO 3 ) 2 (O) 2 ]) and sodium diuranate (Na 2 U 2 O 7 ). The decomposition temperature of Sr(NO 3 ) 2 decreased by 60 °C in the presence of in-situ formed Na 2 U 2 O 7 . The uranium of Na 2 U 2 O 7 intermediate reacts with Sr(NO 3 ) 2 to form various strontium uranium mixed oxides depending on Sr to U ratio in the initial mixtures. During the interaction of Sr(NO 3 ) 2 with Na 2 U 2 O 7 , sodium separates out as amorphous Na 2 O in the mixtures, containing Sr to U ratio ⩾1. Na 2 O phase is not formed in the uranium rich ternary mixture.

Lipase from Thermomyces lanuginosus (TLL) was immobilized in cage-type mesoporous materials via two different protocols, viz. covalent bonding and cross-linking. The comparison between the biocatalysts generated by the two methods on both pure silica mesocellular siliceous foam (MCF) and cage-type large pore mesoporous organosilicas (PMOs) disclosed that cross-linking results in the immobilization of a larger amount of TLL and reduced diffusion problems compared to covalent bonding. Benzene-bridged PMOs positively influence the activity of immobilized lipase due to the hydrophobic properties of the surface. Furthermore, a transesterification reaction in organic solvent was carried out to verify the biocatalytic performance of differently immobilized lipase in both batch and fixed-bed reactors. The results further confirm the superiority of the PMO support compared to MCF and also reveal that the different immobilization protocols strongly influence the activity, stability and specificity of immobilized TLL. Moreover, two commercial available immobilize formed TLL were also used in a fixed-bed reactor under the same condition for comparison.

Sorption of niobium on silica colloids was studied using radiotracer technique in the pH range of 2–11 in NaClO4 medium. Silica was characterized using X-ray diffraction, light scattering and surface area measurements. The point of zero charge for silica colloids was about pH 2. The sorption of niobium was >99 % in the pH range of 3–9 and was slightly lower (~95 %) below pH 3 and above pH 9. The quantitative sorption in the pH range 3–9 could be explained by surface complexation model. The small reduction in sorption was attributed to the existence of small fraction of niobium as cationic species at pH ≤ 2 and anionic species above pH 9. Presence of humic acid was found to have negligible effects on the sorption characteristics.

A colorimetric strip sensor has been developed for selective visual detection and quantification of hydroxide ions in a highly concentrated alkali solutions. The sensor was made by immobilizing the 4,4-bis-[3-(4-nitrophenyl) thiourea]diphenyl ether derivative of thiourea in a Whatman 541 filter paper. Immobilization of the derivative was optimized with respect to its concentration, stability and uniformity in the solid substrate. The sensor strip on reaction with hydroxide ions turns orange in color, and the intensity of the color was found to be proportional to the concentration of hydroxide ions. Developed strip sensor exhibits a wide linear dynamic range of 0.5 M to 8 M and a response time within 5 min. The adequate reproducibility as well as reusability of the strip sensor is suitable for a rapid on-site quantification of hydroxide ions in concentrated alkaline media. Developed strip sensor was successfully applied for the determination of hydroxide concentration in nuclear fuel decladding solutions.

Composites of bismuth and gold nanoparticles (Bi–AuNPs) were prepared on a carbon paste electrode (CPE) by an electrochemical deposition method. The electrochemical parameters were optimized for the effective deposition of Bi–AuNP composite materials. Microscopic examination revealed that nanoparticle clusters of gold were embedded well within the bismuth films (Bi films) over the surface of the CPE. An analytical anodic stripping voltammetry method has been developed for the simultaneous determination of copper and mercury at ultratrace levels using the Bi–AuNP modified CPE. It was possible to observe well separated stripping peaks of the two metal ions and the modified electrode was successfully applied for simultaneous determination of Cu and Hg. The limits of detection using the optimized analytical procedure were observed as 0.16 μg L−1 and 0.28 μg L−1 for Cu and Hg respectively. Interference effects of some of the commonly occurring metal ions were investigated and the method was applied for the determination of Cu and Hg in two ground water and two soil samples collected from different places.

SummaryThe isolation of high quality RNA from different tissues of mango (Mangifera indica L.) is relatively challenging due to the presence of interfering substances such as polysaccharides, polyphenols, and proteins. All these compounds render available isolation protocols useless by reducing the quality (purity and integrity) and quantity of the RNA that can be recovered. Several tissue-specific protocols for the isolation of RNA have been developed specifically for mango, however they are cumbersome, expensive and time-consuming. To overcome these drawbacks, we have developed a comprehensive (CTAB-free, guanidine-free, and LiCl-free) RNA isolation protocol using SDS (sodium dodecyl sulphate) plus phenol which works well for most mango tissues such as leaves, flowers, and fruit, at different stages of development or ripening, as well as fruit peel and seed kernels.This rapid protocol allowed us to process large numbers of samples (12 - 15) simultaneously in a single day. Using this method, we obtained ...

Characterization of neutron energy spectrum along with the determination of sub-cadmium to epithermal neutron flux ratio (f) and the epithermal neutron flux shape factor (α) has been carried out at pneumatic fast transfer system (PFTS) of KAMINI reactor. The facility has been extensively used for the neutron activation analysis (NAA) studies using both k0-NAA and relative method. This paper describes the multi-foil activation method to determine the reaction rates followed by the generation of computed guess spectrum to unfold the neutron spectrum using least square minimization approach.

Background The chemical characterization of metallic alloys and oxides is conventionally carried out by wet chemical analytical methods and/or instrumental methods. Instrumental neutron activation analysis (INAA) is capable of analyzing samples nondestructively. As a part of a chemical quality control exercise, Zircaloys 2 and 4, nimonic alloy, and zirconium oxide samples were analyzed by two INAA methods. The samples of alloys and oxides were also analyzed by inductively coupled plasma optical emission spectroscopy (ICP-OES) and direct current Arc OES methods, respectively, for quality assurance purposes. The samples are important in various fields including nuclear technology. Methods Samples were neutron irradiated using nuclear reactors, and the radioactive assay was carried out using high-resolution gamma-ray spectrometry. Major to trace mass fractions were determined using both relative and internal monostandard (IM) NAA methods as well as OES methods. Results In the case of alloys, compositional analyses as well as concentrations of some trace elements were determined, whereas in the case of zirconium oxides, six trace elements were determined. For method validation, British Chemical Standard (BCS)-certified reference material 310/1 (a nimonic alloy) was analyzed using both relative INAA and IM-NAA methods. Conclusion The results showed that IM-NAA and relative INAA methods can be used for nondestructive chemical quality control of alloys and oxide samples.

A simple, fast and sensitive instrumental neutron activation analysis (INAA) method has been optimized for the determination of trace concentrations of chlorine in five types of samples namely zirconium oxide, zircaloy 2, zircaloy 4, Zr–Nb alloy and Zr–Sn alloy samples. The samples were neutron irradiated for short duration (1 min) using pneumatic carrier facility of Dhruva research reactor at a neutron flux of 5 × 1013 cm−2 s−1 and measurement of 1,642.7 keV gamma-ray of 38Cl was carried out using a 40 % HPGe detector coupled to 8 k MCA. Concentrations of chlorine were found to be in the range of 9–575 mg kg−1. The 3σ detection limits of chlorine were in the range of 0.1–2.7 mg kg−1 for various samples.

A visual strip has been developed for sensing iron in different aqueous samples like natural water and fruit juices. The sensor has been synthesized by UV-radiation induced graft polymerization of acrylamide monomer in microporous poly(propylene) base. For physical immobilization of iron selective reagent, the in situ polymerization of acrylamide has been carried out in the presence of 1,10-phenanthroline. The loaded strip on interaction with Fe(II) in aqueous solution turned into orange red color and the intensity of the color was found to be directly proportional to the amount of Fe(II) in the aqueous sample. The minimal sensor response with naked eye was found for 50 ng mL−1 of Fe in 15 min of interaction. However, as low as 20 ng mL−1 Fe could be quantified using a spectrophotometer. The detection limit calculated using the 3s/S criteria, where ‘s’ is the standard deviation of the absorbance of blank reagent loaded strip and ‘S’ is the slope of the linear calibration plot, was 1.0 ng mL−1. The strip was applied to measure Fe in a variety of samples such as ground water and fruit juices.

In this study we present quantitative elemental analysis techniques like energy dispersive X-ray fluorescence analysis and instrumental neutron activation analysis to assess the impact of industrial discharge on environment. Two cases are discussed, i.e., (a) enrichment of zinc levels in the soil (1080 ± 76 mg kg−1) and zinc uptake ranging between 628 and 40 mg kg−1 in edible plants and cereals grown in agricultural fields near an active zinc smelter, Rajasthan; (b) depth-wise distribution of Cr, Pb and other metals in the sediment core samples from Sundarban wetland, West Bengal, indicating waste discharge from tanneries and other industries.

The pneumatic carrier facility (PCF) of Dhruva reactor is being extensively used for neutron activation analysis (NAA) studies pertaining to research work as well as routine sample analysis. It is useful for the determination of trace elements using short and medium half-lives radioisotopes produced in neutron activation with available higher neutron flux (~5 × 1013 cm−1 s−1). Solid samples placed in high density polypropylene capsule, are irradiated for 1 min duration and radioactive assay is carried out by high resolution gamma ray spectrometry. Design aspects of PCF and various applications to samples of diverse matrices using NAA are presented.

Boron is an important element in nuclear technology. A comparative study was carried out for the determination of boron in borosilicate glass, boron carbide and graphite samples by wet-chemical and nuclear analytical methods. Wet chemical methods namely titrimetry, Inductively Coupled Plasma Mass Spectrometry and ICP Optical Emission Spectrometry and nuclear analytical methods namely Particle Induced Gamma-Ray Emission and Nuclear Reaction Analysis were used. Boron concentrations were in trace (mg kg−1) level in graphite and percentage level in borosilicate glass and boron carbide.

Current studies describe the application of simultaneous TG–DTA–FTIR technique in the in-situ synthesis of tri uranium octaoxide (U3O8) and impurity characterization of the ammonium diuranate (ADU) matrix. Formation of U3O8 could be due to the decomposition of ADU to uranium trioxide (UO3) and finally to U3O8 by the temperature of 500 °C. Presence of carbon and carbonate could be seen as impurities in the matrix. Carbon content has been determined quantitatively using TG and FTIR techniques and the results are in good agreement. Ammonium nitrate was found as impurity in ammonium diuranate matrix. The PXRD studies confirm the formation of U3O8 as end product during the decomposition of ammonium diuranate. From our studies, it is suggested that ammonium diuranate decomposes to tri uranium octaoxide (U3O8) through evolution of nitrogen, hydrogen and oxygen, and not through ammonia evolution in the literature.

Mercury is considered as a highly toxic and widespread heavy-metal pollutant. In the present work, two flat-sheet polymer sorbents have been synthesized for the selective preconcentration of mercury from natural waters. These are a silver nanoparticle (AgNP)-embedded poly(acrylamide)-grafted poly(propylene) sheet (Ag-PAM-PP) and a 1,8-octanedithiol-functionalized gold-coated poly(propylene) sheet (HS-octyl-S-Au-PP). The functional groups acrylamide and thiol provide the binding sites for Hg2+ ions; whereas silver nanoparticles reduce Hg2+ to Hg0 and it is held on the sheet by amalgam formation. Various factors that influence the preconcentration of Hg2+ from aqueous solution were investigated. Based on the comparison of the experimental results, it was observed that Ag-PAM-PP had superior performance for uptake of Hg2+ from natural water samples in terms of sorption capacity, sorption kinetics and working pH range. The uptake of Hg2+was found to be pH dependent with a maximum of 95% at pH 7.5. The preconcentration of Hg2+ from a large volume of aqueous solution was used to extend the lower limit of the concentration range that can be quantified by EDXRF and CV-AAS. The sorbed Hg(II) from aqueous samples was quantitatively detected within 1 min using EDXRF. The LOD (3σ) for CV-AAS (RSD = 2%) and EDXRF (RSD = 5%) were 6 and 30 μg L−1, respectively. The method was applied for the determination of Hg2+ in groundwater and seawater samples in the presence of a high concentration of interfering ions.

A variety of bis heterocycles-heteroaryl pyrazoles (5) and pyrroles (6) were prepared from heteroaryl chalcones adopting 1,3-dipolar cycloaddition reaction and studied their antimicrobial activity. The compounds 5d and 5f having bromo and nitro substituents on the aromatic ring are the potent antimicrobial agents against Bacillus subtilis and Aspergillus niger.

A new class of bis(oxazolyl/thiazolyl/imidazolyl)amidomethanesulfonyl acetamides was prepared from the respective (oxazolyl/thiazolyl/imidazolyl)carbamoyl-methylthio acetic acid and studied their antioxidant activity and cytotoxic activitity against A549 lung adenocarcinoma cells. The methyl-substituted sulfonyl bisoxazoles exhibited excellent radical scavenging activity. On the other hand, the chloro-substituted sulfonyl bisthiazoles (IC50 = 49 A mu M) and sulfonyl bisimidazoles (IC50 = 24 A mu M) showed noticeable cytotoxic activity on A549 cells.

Graphene and its composites have attracted considerable attention in synthesis and electrochemical applications. In the present work, we have synthesized and characterized graphene oxide-bentonite composite (GO-BEN) and utilized it to fabricate an electrochemical sensor. For this, the solution of GO-BEN cast on glassy carbon electrode (GCE) was reduced electrochemically in phosphate buffer solution of pH 6 to obtain electrochemically reduced graphene oxide-bentonite composite (ERGO-BEN-GCE). This ERGO-BEN film was used for electrochemical investigation of an oxazolidinone class of antibiotic, linezolid (LIN) for the first time. The electrochemical sensor showed excellent enhancement and adsorptive ability towards the electrooxidation of LIN. LIN exhibited two each of oxidation and reduction peaks on ERGO-BEN film in phosphate buffer of pH 7.0. Effects of accumulation time, pH of solution and scan rate were studied and various electrochemical parameters were evaluated. The plot of pH versus Ep gave a slope of 26.2 mV/pH in the pH range of 4.2-8.0 indicating the participation of two electrons and one proton in the electrode process. An adsorptive stripping differential pulse voltammetric method (AdSDPV) was developed for the determination of LIN in bulk, pharmaceutical formulations and urine samples. Adsorptive stripping linear sweep voltammetric (AdSLSV) and differential pulse voltammetric (DPV) methods were also developed and the results were compared. LIN showed linear relationship between the current density and concentration in the range of 0.25 - 31.25 μM with a LOD of 0.0337 μM in AdSDPV method; 0.5 - 31.25 μM with a LOD of 0.100 μM in DPV method and 1.25 - 37.5 μM with a LOD of 0.5461 μM in AdSLSV method respectively. The proposed AdSDPV method was observed to be simple, fast and inexpensive and hence, could be readily adopted for quality control in pharmaceutical products.

During this work, size fractionation technique “ultra filtration” is used in physical speciation of thorium in organic rich groundwater. Laboratory simulated experiments were carried out to study the physical speciation of thorium in aquatic environment having elevated level of dissolved humus material classified as dissolved organic carbon (DOC). Samples were collected from organic rich environment having DOC in the range of 50–60 µg mL−1. Th(IV) ions are extremely particle reactive having K d value of the order of 105–6, hence to avoid adsorption on suspended particulate matter, spiking of the solution with Th(NO3)4 was carried out in ground water samples after filtering through 450 nm pore size using suction filtration. Particles in dissolved state (colloids) ranging between 220 nm were separated using suction filtration assembly having a membrane with a pore diameter of 220 nm. Thereafter, solution was sequentially passed through the ultra-filtration membranes having pore diameters of 14 nm [300 k NMWL (nominal molecular weight limit)], 3.1 nm (50 k NMWL), 2.2 nm (30 k NMWL), 1.6 nm (10 k NMWL) and 1.1 nm (0.5 k NMWL) by using “Stirred Ultra-filtration Cells”, operating in concentration mode. Thorium has only one stable oxidation state i.e. IV, under all redox conditions in natural waters and therefore, its speciation is dominated by its interaction with various fractions of DOC. Experimental results show 50–60 % of the spiked Th is in association with fraction enriched with particles of 10 k NMWL (1.6 nm) followed by fraction enriched with particle of 0.5 k NMWL and

The Hydrogenated Diamond Like Carbon (HDLC) thin films are deposited on Silicon substrate at room temperature using asymmetric capacitively coupled RF plasma with varying flow rates of methane. These films are undergone annealing at high vacuum and high temperature furnace. The as-prepared and annealed HDLC films have been depth profiled for hydrogen using the resonance at 6.44 MeV in nuclear reaction between fluoride ion beam and HDLC. The as prepared films exhibit non-uniform depth distribution of hydrogen: it decreases with depth. Annealing in vacuum brings about a significant desorption of hydrogen from the films. Loss of hydrogen, albeit in much lower proportions, is also induced by the bombarding beam. The films also experience a mild loss of carbon, as shown by proton backscattering spectrometry, during high vacuum annealing. The depth profiles of hydrogen in the annealed films are indicative of the prevalence of graphitic carbon near interface between film and substrate., Comment: 16 pages, 6 figures, 3 tables

In the present work, In 3+ substituted cobalt ferrites (CoFe 2 − x In x O 4 , x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) have been synthesized via solid-state reaction technique. The Rietveld fitted X-ray diffraction patterns confirm the formation of single phase cubic spinel structure with space group Fd 3 ¯ m for all the samples, with additional slight traces of secondary phase for x = 0.6, 0.8 and 1.0 samples. The low temperature (5 K)–high field Mossbauer (5 T ) spectra are analyzed in detail for probing the magnetic properties of Fe based In 3+ substituted cobalt ferrites. The canted spin structures associated with Fe 3+ ions both at A- and B-sites in the presence of external magnetic field of 5 T have been noticed in all the samples. A fair agreement is obtained between the experimental integrated intensity ratios of 57 Fe Mossbauer spectra at A- and B-sites and those calculated on the basis of cation distribution. The effect of In 3+ substitution on various Mossbauer parameters viz hyperfine field distribution, isomer shift, quadrupole splitting and the line width has also been noticed. The magnetization measurements performed at low temperature also reveal the canted spin structures in all the samples. The variations in initial permeability over a wide range of frequency (125 kHz–30 MHz) at 300 K have also been recorded. The initial permeability study reveals the occurrence of resonance phenomenon at very high frequencies which widens the area of utility of considered ferrites in the larger operational frequency range for various industrial applications.

Uranium (U) and thorium (Th) are known to cause acute toxicological effects in human, and their compounds are potential occupational carcinogens. During this work, silica microspheres were used to decontaminate the traces of U and Th in different water sources originated from groundwater and lake water. Ultra-filtration technique was used to isolate the microsphere from the water samples. Silica microspheres were synthesized based on a polyvinylpyrrolidone involved emulsion polymerization and subsequent sol–gel process. The microspheres were characterized for their size by using dynamic light scattering, and presence of silicate structure is verified by recording their attenuated total reflectance-Fourier transform infrared spectrum. The surface morphologies of the prepared silica microspheres were studied by using scanning electron microscope. Water samples collected from the groundwater and lake water were spiked with U and Th in the concentration range of 100–1,000 ng mL−1. The results of batch sorption experiments suggest that silica microsphere is very effective at pH 3, and sorption is more than 99.9 %. Equilibrium sorption follows Langmuir isotherms and the maximum U, and Th uptake is 30 and 36 mg g−1, respectively. Major physicochemical characteristics of the water were monitored before and after the decontamination process. Experimental results show no significant variations in any of the measured parameters.

Polyaniline (PAni) was synthesized by a chemical oxidation of aniline, using ammonium persulphate in 1 M HCl and was investigated for radiation stability. The chloride salt as well as the base form of PAni (in air, water and HCl media) was subjected to gamma radiation using a 60 Co source. Radiation induced effect on the stability of PAni was evaluated by the data obtained from elemental analysis and Fourier Transform Infrared (FT-IR) spectroscopy. Anion exchange capacities of PAni before and after gamma irradiation were determined by the neutron activation analysis technique from the measured chloride activity. The ion exchange capacity decreased with increase in the absorbed dose. Chloride form of PAni was more stable towards gamma-radiation compared to the base form.