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Adsorption behavior of the seleno‐amino acids viz. l‐selenomethionine (SeMet) and l‐selenocystine (SeCys) on the surface of Ag nanoparticles (NPs) was investigated by surface‐enhanced Raman scattering (SERS) and X‐ray photoelectron spectroscopy (XPS). The bare and functionalized Ag NPs were characterized by UV‐visible absorption, DLS, zeta‐potential measurements and TEM. The Raman spectrum supported by DFT computed spectrum of SeMet and SeCys suggested the existence of zwitterionic and diselenide (Se‐Se) forms in the crystalline state. The SERS study of SeMet and SeCys indicates that the zwitterionic and diselenide forms, respectively bind to the Ag NPs primarily through the Se atom. In case of SeCys, cleavage of the Se‐Se bond occurs on the Ag NPs surface. SERS results; thus, established the active anchoring sites involved in binding for both seleno‐amino acids and XPS analysis confirmed that Se atom was the most active coordinating site with minor involvement of the carboxylate and amino groups. The SERS study of the seleno‐amino acids showed the possibility of change in orientation of SeMet on the Ag NPs surface with alteration in concentration, while no variation in orientation was observed for SeCys. In this study, sensing of the SeMet and SeCys down to 100 nM level was also achieved. [ABSTRACT FROM AUTHOR]

The authors have investigated beneficial effects of 1 mM of silver nanoparticles (AgNPs) on agriculturally important plant Pennisetum glaucum (Bajara). The extracellular AgNPs were synthesised using Bacillus subtilis spizizenni and characterised using ultraviolet-visible absorption spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM). Optical absorption spectrum showed characteristic peak of AgNPs at 423 nm. FT-IR analysis of AgNPs showed peak at 3435 cm-1, which indicates the presence of N-H group (primary, secondary amines and amides) on the surface of AgNPs. TEM studies indicate that synthesised AgNPs have average size of ~2 nm. Energy dispersive X-ray spectroscopy showed strong signal of Ag at 3 keV. Treatment of 1 mM AgNPs to the bajara seeds was found to be sufficient for excellent germination of seeds within 3 days. There was also significant increase in radicle and plumule length as compared with control bajara seeds according to statistical analysis by one-way analysis of variance, followed by Tukey's test. The percentage of AgNPs detected in root samples was 0.003% (by inductively coupled plasma atomic emission spectroscopy), which is negligible. There is still need to study the bioavailability and the type of interaction of AgNPs with plants, necessary for application in agriculture. [ABSTRACT FROM AUTHOR]

The present paper outlines the catalytic thermolysis of Jatropha oil carried out in laboratory model fixed bed reactor varying temperature between 340 and 420°C and at liquid hourly space velocity (LHSV) 1.12, 1.87, and 2.25 h−1. Three heterogeneous catalysts, comprising of Amorphous Alumino-Silicate (AAS) loaded separately with titania (TiO2), zirconia (ZrO2) and ceria (CeO2), were successfully synthesized and used in the reaction. The study reveals that the maximum distilled liquid biofuel yield of 71% by volume could be achieved through zirconia impregnated catalyst at 380°C and 1.87 h−1 LHSV. Reaction products mainly consist of liquid and gaseous hydrocarbons along with the carbon dioxide, coke, and water. The liquid product is a crude mixture of various components and hence distilled out into four fractions over the temperature range of 60-200°C. The physical properties like boiling point, specific gravity, viscosity, and calorific value of distilled biofuel fraction 1 resembles the properties of petrol whereas fractions 2 and 3 resemble diesel. Suitable blends of these fractions lead to cleaner biofuel. Life of catalyst could be enhanced by nitrogen purging practice at moderate temperature. Yield and quality of distilled biofuel product were improved by using hydroquinone as a polymerization inhibitor. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 749-757, 2017 [ABSTRACT FROM AUTHOR]

Polymeric materials have been found to be ideal candidates for the synthesis of organic-inorganic nanomaterials. We have obtained Co3O4-decorated graphene oxide (GO) nanocomposites by a simple polymer combustion method. Polyvinyl alcohol (PVA) of two different molecular weights, 14,000 and 125,000, was used for the synthesis. The pristine sample was annealed at 300, 500, and 800°C. PVA has played an important role in the formation of GO and Co3O4 nanoparticles. Synthesized Co3O4-GO nanocomposites were characterized by X-ray diffraction, Fourier transform infrared, Raman, electron paramagnetic resonance, transmission electron microscopy, and vibrating sample magnetometry. Reflection peaks at 12° and 37° in an X-ray study confirm the formation of Co3O4-GO. Raman study validates the presence of GO in nanocomposites of Co3O4-GO. Room temperature ferromagnetism was observed in all annealed samples. The highest coercivity of 462 G was observed for 300°C annealed samples as compared with bulk Co3O4. On the basis of the results obtained, a mechanism of formation is proposed. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: A useful method for the synthesis of Au nanoparticles is presented. The synthesis of Au nanoparticles with various morphologies was carried out at room temperature using gamma radiolysis and NaBH4 reduction of HAuCl4 in N,N′-dimethylformamide:water solutions containing polyoxometalate (POM). The results demonstrated that by controlling the rate of reduction and ratio of DMF and water, metal particle size and shape can be further tailored. It is shown that gold nanoparticles with controllable size can be synthesized. In principle, the general finding of this work can be extended to other transition/noble metal nanoparticles. [Copyright &y& Elsevier]

Biomodified CdS nanoparticles were synthesized using l-cysteine as a capping agent in the colloidal state as a function of pH. The role of pH on the size and structure of CdS nanoparticles was investigated in detail. At pH 7.4 and 9.1, X-ray diffraction spectra of as prepared samples showed the presence of a mixture of cubic and hexagonal phases while cubic phase was formed at pH 11.2. A gradual transition to the hexagonal phase was observed for refluxed samples at pH 9.1 and 11.2. Whereas, at pH 7.4, the sample remains in a mixture of cubic and hexagonal phase even after refluxing. The particle size of as prepared samples was about 2 nm, and for refluxed samples the size increased up to 10 nm. The binding of cadmium through thiol group is evidenced by infrared spectra. An intense band due to C−C−N vibration was observed after 24 h of reflux. The formation of a specific molecular cluster determines the growth of a particular phase. Transmission electron microscopy (TEM) studies support the X-ray diffraction (XRD) studies and exhibit well separated spherical particles while refluxed samples show clustering. [ABSTRACT FROM AUTHOR]

Ag@CdS quantum dots were synthesized by a colloidal method. CdS nanoparticles stabilized by l-cysteine were doped with varying silver concentrations. Ag@CdS nanoparticles were characterized by UV−visible spectroscopy, steady-state and time-resolved fluorescence, X-ray diffraction, Fourier transform infrared resonance (FTIR), and transmission electron microscopy. The effect of dopant concentration and effect of aging of Ag@CdS colloids were studied. At low silver content, emission was found to enhance, while at high silver content, emission quenching was observed after aging. Ag-CdS nanocolloids exhibited multiexponential decay with τ2being a long-lived component. X-ray diffraction spectra of as prepared samples indicated that silver occupies an interstitial position, while for annealed samples, Ag+ions get oxidized to Ag2+and substituted for Cd2+in the CdS lattice. FTIR studies have shown that cysteine acts as a monodentate ligand for cadmium and silver for as-prepared sample, whereas it acts as a tridentate ligand for annealed samples toward silver. Transmission electron microscopy of as-prepared samples showed spherical-shaped composites with a uniform layer of capping molecules. [ABSTRACT FROM AUTHOR]

Abstract: A study has been undertaken on the effect of crystallization method on the IV↔III transition of ammonium nitrate (AN). AN is crystallized in three different ways, viz. recrystallization, evaporative crystallization and melt crystallization. When the samples were crystallized from saturated aqueous solution, ideal crystals were formed, which behaved differently from the crystals formed from the other methods. The DTA examination of the crystals showed that the crystals have different transition behaviour. The moisture uptake of the samples determined were found to have influenced by the mode of crystallization. The samples were further analyzed by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The present study showed that the parameters like thermal history, number of previous transformations and moisture content have a very negligible influence on the IV↔III transition of AN as compared to the method of crystallization. [Copyright &y& Elsevier]

The catalytic effect of two different sizes of α-Fe2O3 nanoparticles synthesised using an electrochemical method was investigated on the thermal decomposition of ammonium perchlorate (AP) using differential scanning calorimetry as a function of catalyst concentration. The nanosized ferric oxide particles exhibited more of a catalytic effect on the thermal decomposition of AP than commercial α-Fe2O3 particles. A lowering of the high-temperature decomposition of AP by 59 °C was observed after mixing with 2 Wt per cent of α-Fe2O3 particles with the very fine size of 3.5 nm. The mixture produced a high heat release of 4.574 kJ/ g compared to 0.834 kJ/g of pure AP. The kinetic parameters were evaluated using Kissinger method. The decrease in the activation energy and increase in rate constant confirmed the catalytic activity of these nanoparticles. [ABSTRACT FROM AUTHOR]

Abstract: Zinc oxide (ZnO) nanobeads were synthesized by aqueous polymer thermolysis method in air. The precursor powders were prepared using different polymers of varied molecular weights. The influence of annealing temperature from 300 to 1000°C on thermal properties of polymer gel precursors and ZnO nanoparticles is investigated systematically using thermogravimetric analysis (TGA). The nature and structure of different polymers and their affinity towards the solvent seem to be responsible for the formation of ZnO and their surface morphology. X-ray diffraction studies of the synthesized ZnO show polycrystalline hexagonal zincite syn structure. The composition and microstructural features of polycrystalline samples of zinc oxide were studied by FTIR, SEM and TEM. Infrared spectra reveal the formation of zinc oxide and the removal of organic matter at higher temperature. The as prepared samples, synthesized by poly-vinyl alcohol (PVA) of molecular weight 14,000 and 125,000 were decomposed by heating in air, resulting in the formation of spherical and cuboid shapes of ZnO. The results are compared with those of poly-vinyl pyrrolidone (PVP) capped ZnO. The smallest grain size was found in presence of PVP. The role of polymer interactions in the synthesis for obtaining well-dispersed crystallites has also been demonstrated. [Copyright &y& Elsevier]

Mesoporous ZnO nanoparticles (NPs) were successfully synthesized by simple electrochemical method using tetrabutyl ammonium bromide (TBAB) as a stabilizer in different polar protic solvents viz. water, ethanol and their mixture. XRD and Raman scattering analysis indicate the formation of pure hexagonal phase ZnO in pure ethanol as well as in water-ethanol mixture, while synthesis in pure water gives mixture of hexagonal ZnO and orthorhombic Zn(OH) 2 . FE-SEM micrographs show that ethanol as an electrolytic medium yields globular cluster of nanospheres, while involvement of water as an electrolyte gives spindle shaped cluster of quasi-spherical NPs. Band gap value of the ZnO NPs synthesized in ethanol was found to be higher, (3.65 eV) than those synthesized in water-ethanol mixture (3.50 eV) and pure water (3.35 eV). Significant enhancement in surface area was also observed with variation in the reaction medium from aqueous (45 m 2 g − 1 ) to alcoholic (160 m 2 g − 1 ). Sample synthesized in ethanol hence showed highest photo-degradation of methylene blue (MB) dye. The rate constant value for this sample was higher (0.0793 min − 1 ) than the values for sample synthesized in water-ethanol mixture (0.0242 min − 1 ) and pure water (0.0139 min − 1 ). The possible mechanism of formation of ZnO NPs as well as degradation of MB is proposed. [ABSTRACT FROM AUTHOR]

Abstract: This report aimed to study the effect of CdS doping in TiO2 on the phase transformation of TiO2 from anatase to rutile using X-ray diffraction (XRD) and Raman spectroscopy. CdS-doped TiO2 nanocomposites have been prepared and characterized using Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). We have observed that contrary to bare TiO2, phase transformation of TiO2 from anatase to rutile is hindered when doped with CdS at high temperature. Raman spectroscopy is found to be more sensitive for detection of the surface of TiO2 as compared to XRD. [Copyright &y& Elsevier]

Present methods for the disposal of old and rejected ammunition carry high risk and are not environment-friendly. Various processes such as wet air oxidation, molten salt oxidation, hydro thermal oxidation, incineration, electrochemical reduction, biodegradation and other methods have limited use for decontamination and are not suitable for disposal of large quantities of explosives. Thus there is dire need to develop alternate method for safe disposal of rejected explosives which will be eco-friendly. In this paper we have attempted to combine two methods i.e. chemical treatment followed by biological/microbiological treatment. For this purpose we have selected Tri Nitro Toluene (TNT) as a model compound, which is used extensively in many types of ammunition. As reported previously from our laboratory the presence of nitro group from TNT was toxic to bacterial growth. By chemical treatment, nitro groups from TNT were converted into amine and mixed in soil for biodegradation. Our results suggest that after converting 'nitro groups' to 'amine groups' were much preferred by bacteria and faster mineralization is observed. Thus combined treatment to TNT as discussed in this study, showed much less phyto-toxicity and may have great potential to scale up the process for large quantities of explosive such as TNT.

Superparamagnetic ZnFe2O4 nanoparticles with size range of 28-38 nm were synthesized by polyol process based on use of varying chain length glycols as solvent. We have offered, for the first time, the plausible mechanism behind in situ formation of zinc ferric oxalate hydroxide hydrate [Fe2Zn(C2O4)2(OH)3](+)·4H2O complex from diethylene and polyethylene glycol. We are also reporting, the magnetic properties of above complexes. We have found a ferromagnetic ordering in precursor complex compounds. The intermediate hydrocarbon chain between the oxalato bridged metal cations plays a crucial role in obtaining anomalous magnetic behavior. ZnFe2O4 nanoparticles obtained after annealing the DEGylated precursor complex (precursor complex formed in diethylene glycol) showed the highest superparamagnetic (SPM) behavior (22.4 emu g(-1)) among others. The reasons for anomalous SPM behavior of ZnFe2O4 nanoparticles are explained on the basis of the degree of inversion of the spinel structure, high surface-to-volume ratio, which causes non-collinear spin arrangement in a surface layer and higher oxygen concentration on the surface of dead organic layer, which increases the unpaired valence electrons leading to uncompensated surface spins.

Crystalline flowerlike ZnO was synthesized by an aminolytic reaction at the air-liquid interface in an aqueous media at an alkaline pH. A thin visible film was formed at the air-liquid interface by self-assembly of flowerlike ZnO. Diffraction studies show rearrangement of the single crystalline units at the air-liquid interface leading to the formation of nanobelts. These nanobelts overlap systematically to form petals of the flowerlike structure; individual petals get curved with time. Each nanobelt is found to be single crystalline and can be indexed as the hexagonal ZnO phase. The organic product formed in the aminolytic reaction and dissolution-reprecipitation mechanism is the driving force for the formation of flowerlike ZnO at the air-liquid interface. A clear relationship between the surface, photocatalytic, and photoluminescent properties of ZnO is observed. The flowerlike structure exhibits a blue shift (3.56 eV) in the band emission as compared to bulk ZnO (3.37 eV). The photodegradation of methylene blue over the flowerlike ZnO catalyst formed at the air-liquid interface and in the sediments shows enhanced photocatalytic activity. The sub-bands formed due to surface defects facilitate separation of charge carriers increasing their lifetime, leading to enhanced photocatalytic activity of flowerlike ZnO., (© 2011 American Chemical Society)

The evolution of Ag nanoparticles by photochemical reduction method and the effect of biotin on their UV-Visible absorption spectrum were studied. Surface modification studies were carried out on chemically reduced Ag nanoparticles. ATR-FTIR studies showed that the biotin molecules bind with the surface of Ag nanoparticles through the oxygen of the carboxylate group. Theoretical calculations were carried out on the structure of the biotin and the silver complex of biotin (biotin(-)-Ag+) by optimizing their structures using density functional calculations with the B3LYP method using the LANL2DZ basis set. Theoretical calculations and experimental evidence favors a preferential binding of biotin molecule to Ag nanoparticles through the carboxylate group.