Structural,magnetic and Mössbauer spectral studies of nanosize aluminum substituted nickel zinc ferrites

Nanosize aluminum substituted nickel zinc ferrites were prepared through aerosol route and characterized using TEM, XRD, magnetic measurements and Mössbauer spectroscopy. The particle size of as obtained samples was found to be ∼10 nm which increases up to ∼85 nm upon annealing at 1200 °C. The unit cell parameter ‘a’ decreases linearly with concentration of aluminum due to the small ionic radius of aluminum. The saturation magnetization for all the samples after annealing at 1200 °C lies in the range 12.9–72.6 emu/g and decreases linearly with concentration of aluminum. Room temperature Mössbauer spectra of all as obtained samples of ferrite compositions exhibited a broad doublet suggesting super paramagnetic nature. This doublet is further resolved into two doublets and assigned to the surface region and internal region atoms of the particles. The samples annealed at 1200 °C show broad sextets, which were fitted with five sextets, indicating different local environment of both tetrahedrally and octahedrally coordinated Fe cation.     

Individually addressable recessed gold microelectrode arrays with monolayers of thio-cyclodextrin nanocavities

Four, individually addressable 30 microm diameter, e-beam deposited, gold microelectrodes recessed by 6 microm were suitably spaced on a single substrate to avoid diffusional overlap between each microelectrode. The single substrate device was functionalised with thiolated alpha-, beta-, and gamma-cyclodextrin nanocavities without spacer groups to ensure close proximity of the cavities to the electrode surface. The microelectrodes were assessed in two stages. The e-beam deposited micron sized electrodes were characterized using models for recessed and inlaid microdisk electrodes. Subsequently, each individually addressable, atomically flat, micro-patterned gold electrode with thiolated CD ensembles was treated as a nanoporous electrode assembly. Theoretical and experimental results were compared using cyclic voltammetry. Atomic force microscopy was also used to characterise the modified microelectrodes. Comparisons were made with thiolated CDs deposited on macroelectrodes. This is the first report of the behaviour of immobilized CD nanocavities ensembles on atomically flat gold microelectrodes.     

Dynamic and Equilibrium Studies on Adsorption of Cu(II) Ions onto Biopolymeric Cross-Linked Pectin and Alginate Beads

Binary biopolymeric beads of alginate and pectin were prepared and characterized by FTIR spectra. On to the surfaces of the prepared beads were performed static and dynamic adsorption studies of Cu(II) ions at fixed pH and ionic strength of the aqueous metal ion solutions. The adsorption data were applied to Langmuir and Freundlich isotherm equations and various adsorption parameters were calculated. The influence of various experimental parameters such as effect of time, pH, temperature, solid to liquid ratio, and the presence of salts were investigated on the adsorption of copper ions.     

Plumbagin Alleviates Intracerebroventricular-Quinolinic Acid Induced Depression-like Behavior and Memory Deficits in Wistar Rats

Plumbagin, a hydroxy-1,4-naphthoquinone, confers neuroprotection via antioxidant and anti-inflammatory properties. The present study aimed to assess the effect of plumbagin on behavioral and memory deficits induced by intrahippocampal administration of Quinolinic acid (QA) in male Wistar rats and reveal the associated mechanisms. QA (300 nM/4 μL in Normal saline) was administered i.c.v. in the hippocampus. QA administration caused depression-like behavior (forced swim test and tail suspension tests), anxiety-like behavior (open field test and elevated plus maze), and elevated anhedonia behavior (sucrose preference test). Furthermore, oxidative–nitrosative stress (increased nitrite content and lipid peroxidation with reduction of GSH), inflammation (increased IL-1β), cholinergic dysfunction, and mitochondrial complex (I, II, and IV) dysfunction were observed in the hippocampus region of QA-treated rats as compared to normal controls. Plumbagin (10 and 20 mg/kg; p.o.) treatment for 21 days significantly ameliorated behavioral and memory deficits in QA-administered rats. Moreover, plumbagin treatment restored the GSH level and reduced the MDA and nitrite level in the hippocampus. Furthermore, QA-induced cholinergic dysfunction and mitochondrial impairment were found to be ameliorated by plumbagin treatment. In conclusion, our results suggested that plumbagin offers a neuroprotective potential that could serve as a promising pharmacological approach to mitigate neurobehavioral changes associated with neurodegeneration.     

Synthesis,characterization and role of zero-valent iron nanoparticle in removal of hexavalent chromium from chromium-spiked soil

Chromium is an important industrial metal used in various products/processes. Remediation of Cr contaminated sites present both technological and economic challenges, as conventional methods are often too expensive and difficult to operate. In the present investigation, Zero-valent iron (Fe⁰) nanoparticles were synthesized, characterized, and were tested for removal of Cr(VI) from the soil spiked with Cr(VI). Fe⁰ nanoparticles were synthesized by the reduction of ferric chloride with sodium borohydride and were characterized by UV–Vis (Ultra violet–Visible) and FTIR (Fourier transform infrared) spectroscopy. The UV–Vis spectrum of Fe⁰ nanoparticles suspended in 0.8% Carboxymethyl cellulose showed its absorption maxima at 235 nm. The presence of one band at 3,421 cm⁻¹ ascribed to OH stretching vibration and the second at 1,641 cm⁻¹ to OH bending vibration of surface-adsorbed water indicates the formation of ferrioxyhydroxide (FeOOH) layer on Fe⁰ nanoparticles. The mean crystalline dimension of Fe⁰ nanoparticles calculated by XRD (X-ray diffraction) using Scherer equation was 15.9 nm. Average size of Fe⁰ nanoparticles calculated from TEM (Transmission electron microscopy) images was found around 26 nm. Dynamic Light Scattering (DLS) also showed approximately the same size. Batch experiments were performed using various concentration of Fe⁰ nanoparticles for reduction of soil spiked with 100 mg kg⁻¹ Cr(VI). The reduction potential of Fe⁰ nanoparticles at a concentration of 0.27 g L⁻¹ was found to be 100% in 3 h. Reaction kinetics revealed a pseudo-first order kinetics. Factors like pH, contact time, stabilizer, and humic acid facilitates the reduction of Cr(VI).     

Synthesis and antimicrobial activities of sulfonohydrazide‐substituted 8‐hydroxyquinoline derivative and its oxinates

Looking at the pharmacological importance of 8‐hydroxyquinolines and sulfonamides, in the present study, a novel bi‐dentate ligand 4‐amino‐N′‐[(8‐hydroxyquinoline‐5‐yl)methyl] benzenesulfonohydrazide (AHQMBSH) having above both moieties within a single molecular framework was synthesized by the reaction of N‐acetamidobenzene sulfonohydrazide with 5‐chloromethyl‐8‐hydroxyquinoline hydrochloride. Its metal(II) oxinates were also prepared with Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) salts. All the above compounds were investigated by physicochemical analyses, thermogravimetric analysis and spectroscopic techniques. Antimicrobial activities for the above prepared compounds were carried out using the agar‐plate method against various strains of bacteria (Staphylococcus aureus, Bacillus subtillis, Pseudomonas aerugionsa, Escherichia coli) and fungi (Aspergillus niger and Aspergillus flavous). The results show a significant increase in antimicrobial and antifungal activities of AHQMBSH compared with the parent 8‐hydroxyquinoline and sulfonamides. Copyright © 2010 John Wiley & Sons, Ltd.     

Implementation of anti-reflection coating to enhance light out-coupling in organic light-emitting devices

We report significant enhancement of light out-coupling in organic light-emitting devices (OLEDs) by means of anti-reflection coating of magnesium fluoride (MgF₂) on the backside of glass substrate. OLEDs were fabricated by employing the green electrophosphorescent material fac tris-(2-phenylpyridine) iridium [Ir(ppy)₃] doped in 4,4′,8-N,N-8-dicarbazole-biphenyl (CBP) and 0.4 wt% tetrafluorotetracyano-quinodimethane (F4-TCNQ)-doped naphthylphenylbiphenyl diamine (α-NPD) as hole transport layer (HTL). Single-layer MgF₂ with the thickness of λ/4 was then vacuum deposited on the backside of glass substrate of OLED. About two-fold enhancement in luminance with anti-reflection coating of MgF₂ has been observed.     

Studies on drug–DNA complexes,adriamycin–d‐(TGATCA)2 and 4′‐epiadriamycin–d‐(CGATCG)2, by phosphorus‐31 nuclear magnetic resonance spectroscopy

The complexes of adriamycin–d‐(TGATCA)₂ and 4′‐epiadriamycin–d‐(CGATCG)₂ are studied by one‐ and two‐dimensional ³¹P nuclear magnetic resonance spectroscopy (NMR) at 500 MHz in the temperature range 275–328 K and as a function of drug to DNA ratio (0.0–2.0). The binding of drug to DNA is clearly evident in ³¹P? ³¹P exchange NOESY spectra that shows two sets of resonances in slow chemical exchange. The phosphate resonances at the intercalating steps, T1pG2/C1pG2 and C5pA6/C5pG6, shift downfield up to 1.7 ppm and that at the adjacent step shift downfield up to 0.7 ppm, whereas the central phosphate A3pT4 is relatively unaffected. The variations of chemical shift with drug to DNA ratio and temperature as well as linewidths are different in each of the two complexes. These observations reflect change in population of B_I/B_II conformation, stretching of backbone torsional angle ζ, and distortions in O? P? O bond angles that occur on binding of drug to DNA. To the best of our knowledge, there are no solution studies on 4′‐epiadriamycin, a better tolerated drug, and binding of daunomycin or its analogue to d‐(TGATCA)₂ hexamer sequence. The studies report the use of ³¹P NMR as a tool to differentiate various complexes. The specific differences may well be the reasons that are responsible for different antitumor action of these drugs due to different binding ability and distortions in DNA. Copyright © 2009 John Wiley & Sons, Ltd.     

The mechanism of sonochemical degradation of a cationic surfactant in aqueous solution

The sonochemical degradation of the cationic surfactant, laurylpyridinium chloride (LPC), in water was studied at concentrations of 0.1-0.6 mM, all below its critical micelle concentration (15 mM). It has been found that the initial step in the degradation of LPC occurs primarily by a pyrolysis pathway. Chemical analysis of sonicated solutions by gas chromatography, electrospray mass spectrometry, and high performance liquid chromatography reveals that a broad range of decomposition products, hydrocarbon gases and water-soluble species, are produced. Propionamide and acetamide were identified as two of the degradation intermediates and probably formed as the result of the opening of the pyridinium ring following OH radical addition. Most of the LPC is eventually converted into carboxylic acids. The complete mineralization of these carboxylic acids by sonolysis is however a comparatively slow process due to the hydrophilic nature of these low molecular weight products.