Impact of spray flux density and vacuum annealing on the transparent conducting properties of doubly doped (Sn plus F) zinc oxide films deposited using a simplified spray technique

In this investigation transparent conducting properties of as-deposited and annealed ZnO:Sn:F films deposited using different spray flux density by changing the solvent volume (10 mL, 20 mL ... 50 mL) of the starting solutions have been studied and reported. The structural analyses of the films indicate that all the films have hexagonal wurtzite structure of ZnO with preferential orientation along (002) plane irrespective of the solvent volume and annealing treatment whereas, the overall crystalline quality of the films is found to be enhanced with the increase in solvent volume as well as with annealing. This observed enhancement is strongly supported by the optical and surface morphological results. From the measurements of electrical parameters, it is seen that, the annealed films exhibit better electrical properties compared to the as-deposited ones. Annealing has caused agglomeration of grains as confirmed by the surface morphological studies. Also, the annealing process has led to an improvement in the optical transparency as well as band gap. It is found from the analyses of the characteristics of the as- deposited and annealed films that the annealed film deposited from starting solution having solvent volume of 50 mL is optimal in all respects, as it possesses all the desirable characteristics including the quality factor (1.60 x 10(-4) (Omega/sq.)(-1)). (C) 2014 Elsevier Ltd. All rights reserved.

Serum proteomics of hepatitis C virus infection reveals retinol-binding protein 4 as a novel regulator

Persistent infection of hepatitis C virus (HCV) can lead to liver cirrhosis and hepatocellular carcinoma, which are currently diagnosed by invasive liver biopsy. Approximately 15-20% of cases of chronic liver diseases in India are caused by HCV infection. In North India, genotype 3 is predominant, whereas genotype 1 is predominant in southern parts of India. The aim of this study was to identify differentially regulated serum proteins in HCV-infected Indian patients (genotypes 1 and 3) using a two-dimensional electrophoresis approach. We identified eight differentially expressed proteins by MS. Expression levels of one of the highly upregulated proteins, retinol-binding protein 4 (RBP4), was validated by ELISA and Western blotting in two independent cohorts. We also confirmed our observation in the JFH1 infectious cell culture system. Interestingly, the HCV core protein enhanced RBP4 levels and partial knockdown of RBP4 had a positive impact on HCV replication, suggesting a possible role for this cellular protein in regulating HCV infection. Analysis of RBP4-interacting partners using a bioinformatic approach revealed novel insights into the possible involvement of RBP4 in HCV-induced pathogenesis. Taken together, this study provided information on the proteome profile of the HCV-infected Indian population, and revealed a link between HCV infection, RBP4 and insulin resistance.

Enhancement of Corrosion Resistance of Zinc Coatings Using Green Additives

In the present work, morphology, microstructure, and electrochemical behavior of Zn coatings containing non-toxic additives have been investigated. Zn coatings were electrodeposited over mild steel substrates using Zn sulphate baths containing four different organic additives: sodium gluconate, dextrose, dextrin, and saccharin. All these additives are ``green'' and can be derived from food contents. Morphological and structural characterization using electron microscopy, x-ray diffraction, and texture co-efficient analysis revealed an appreciable alteration in the morphology and texture of the deposit depending on the type of additive used in the Zn plating bath. All the Zn coatings, however, were nano-crystalline irrespective of the type of additive used. Polarization and electrochemical impedance spectroscopic analysis, used to investigate the effect of the change in microstructure and morphology on corrosion resistance behavior, illustrated an improved corrosion resistance for Zn deposits obtained from plating bath containing additives as compared to the pure Zn coatings.

Comparison of the photocatalytic degradation of trypan blue by undoped and silver-doped zinc oxide nanoparticles

Zinc oxide (ZnO) and silver doped zinc oxide (ZnO:Ag) nanoparticles were prepared using nitrates of zinc and silver as oxidizers and ethylene diaminetetraacetic acid (EDTA) as a fuel via low-temperature combustion synthesis (LCS) at 500 degrees C. X-ray diffraction (XRD) pattern indicates the presence of silver in the hexagonal wurtzite structure of ZnO. Fourier transform infrared (FTIR) spectrum indicates the presence of Ag-Zn-O stretching vibration at 510 cm(-1). Transmission electron microscopy (TEM) images shows that the average particle size of ZnO and ZnO:Ag nanoparticles were found to be 58 nm and 52 nm, respectively. X-ray photoelectron spectroscopy (XPS) data clearly indicates the presence of Ag in ZnO crystal lattice. The above characterization techniques indicate that the incorporation of silver affects the structural and optical properties of ZnO nanoparticles. ZnO:Ag nanoparticles exhibited 3% higher photocatalytic efficiency than pure ZnO nanoparticles. ZnO:Ag nanoparticles show better photocatalytic activity for the degradation of trypan blue (TrB) compared to undoped ZnO nanoparticles. (C) 2014 Elsevier Ltd. All rights reserved.

Zinc oxide based photocatalysis: tailoring surface-bulk structure and related interfacial charge carrier dynamics for better environmental applications

As an alternative to the gold standard TiO2 photocatalyst, the use of zinc oxide (ZnO) as a robust candidate for wastewater treatment is widespread due to its similarity in charge carrier dynamics upon bandgap excitation and the generation of reactive oxygen species in aqueous suspensions with TiO2. However, the large bandgap of ZnO, the massive charge carrier recombination, and the photoinduced corrosion-dissolution at extreme pH conditions, together with the formation of inert Zn(OH)(2) during photocatalytic reactions act as barriers for its extensive applicability. To this end, research has been intensified to improve the performance of ZnO by tailoring its surface-bulk structure and by altering its photogenerated charge transfer pathways with an intention to inhibit the surface-bulk charge carrier recombination. For the first time, the several strategies, such as tailoring the intrinsic defects, surface modification with organic compounds, doping with foreign ions, noble metal deposition, heterostructuring with other semiconductors and modification with carbon nanostructures, which have been successfully employed to improve the photoactivity and stability of ZnO are critically reviewed. Such modifications enhance the charge separation and facilitate the generation of reactive oxygenated free radicals, and also the interaction with the pollutant molecules. The synthetic route to obtain hierarchical nanostructured morphologies and study their impact on the photocatalytic performance is explained by considering the morphological influence and the defect-rich chemistry of ZnO. Finally, the crystal facet engineering of polar and non-polar facets and their relevance in photocatalysis is outlined. It is with this intention that the present review directs the further design, tailoring and tuning of the physico-chemical and optoelectronic properties of ZnO for better applications, ranging from photocatalysis to photovoltaics.

Temperature dependent current-voltage characteristics of zinc oxide nanowire/polypyrrole nanocomposite

Temperature dependent current-voltage (I-V) measurements of electrochemically prepared zinc oxide nanowire/polypyrrole (ZnONW/PPy) nanocomposite yielded non-linear I-V characteristics at temperatures between 300 and 4.5 K. The low-field conductance (G) of the ZnONW/PPy film exhibits pronounced temperature dependence with room temperature conductance (G(300K)) similar to 10(-3) S and a conductance ratio (G(300)K/G(4.5K)) of similar to 10(4), indicating dominance of significant temperature dependent charge transport processes. The conduction mechanism of the film is satisfactorily understood by extended fluctuation induced tunneling (FIT) model as the non-linear I-V characteristics fit fairly well to the extended FIT model. Further, the temperature dependence of G(o) obtained from fitting followed Sheng's model also. (C) 2014 AIP Publishing LLC.

Electronically nonadiabatic decomposition mechanisms of clusters of zinc and dimethylnitramine

Electronically nonadiabatic decomposition mechanisms of dimethylnitramine (DMNA) in presence of zinc metal clusters are explored. Complete active space self-consistent field (CASSCF) calculation is employed for DMNA-Zn and ONIOM (Our own N-layered integrated molecular orbital and molecular mechanics) methodology is coupled with CASSCF methodology for DMNA-Zn-10 cluster. Present computational results show that DMNA-Zn clusters undergo electronically nonadiabatic reactions, rendering nitro-nitrite isomerization followed by NO elimination. The overall reactions are also found to be highly exothermic in nature. This is the first report on electronically nonadiabatic decomposition pathways of DMNA-Zn-n neutral clusters. (C) 2014 Elsevier B.V. All rights reserved.

Synthesis, crystal structure and spectroscopic and electrochemical properties of bridged trisbenzoato copper-zinc heterobinuclear complex of 2,2 `-bipyridine

The synthesis of the heterobinuclear copper-zinc complex CuZn(bz)(3)(bpy)(2)]ClO4 (bz = benzoate) from benzoic acid and bipyridine is described. Single crystal X-ray diffraction studies of the heterobinuclear complex reveals the geometry of the benzoato bridged Cu(II)-Zn(II) centre. The copper or zinc atom is pentacoordinate, with two oxygen atoms from bridging benzoato groups and two nitrogen atoms from one bipyridine forming an approximate plane and a bridging oxygen atom from a monodentate benzoate group. The Cu-Zn distance is 3.345 angstrom. The complex is normal paramagnetic having mu(eff) value equal to 1.75 BM, ruling out the possibility of Cu-Cu interaction in the structural unit. The ESR spectrum of the complex in CH3CN at RT exhibit an isotropic four line spectrum centred at g = 2.142 and hyperfine coupling constants A(av) = 63 x 10(-4) cm(-1), characteristic of a mononuclear square-pyramidal copper(II) complexes. At LNT, the complex shows an isotropic spectrum with g(parallel to) = 2.254 and g(perpendicular to) =2.071 and A(parallel to) = 160 x 10(-4) cm(-1). The Hamiltonian parameters are characteristic of distorted square pyramidal geometry. Cyclic voltammetric studies of the complex have indicated quasi-reversible behaviour in acetonitrile solution. (C) 2014 Elsevier B.V. All rights reserved.

Efficacious Gene Silencing in Serum and Significant Apoptotic Activity Induction by Survivin Downregulation Mediated by New Cationic Gemini Tocopheryl Lipids

Nonviral gene delivery offers cationic liposomes as promising instruments for the delivery of double-stranded RNA (ds RNA) molecules for successful sequence-specific gene silencing (RNA interference). The efficient delivery of siRNA (small interfering RNA) to cells while avoiding unexpected side effects is an important prerequisite for the exploitation of the power of this excellent tool. We present here six new tocopherol based cationic gemini lipids, which induce substantial gene knockdown without any obvious cytotoxicity. All the efficient coliposomal formulations derived from each of these geminis and a helper lipid, dioleoylphosphatidylethanolamine (DOPE), were well characterized using physical methods such as atomic force microscopy (AFM) and dynamic light scattering (DLS). Zeta potential measurements were conducted to estimate the surface charge of these formulations. Flow cytometric analysis showed that the optimized coliposomal formulations could transfect anti-GFP siRNA efficiently in three different GFP expressing cell lines, viz., HEK 293T, HeLa, and Caco-2, significantly better than a potent commercial standard Lipofectamine 2000 (L2K) both in the absence and in the presence of serum (FBS). Notably, the knockdown activity of coliposomes of gemini lipids was not affected even in the presence of serum (10% and 50% FBS) while it dropped down for L2K significantly. Observations under a fluorescence microscope, RT-PCR, and Western blot analysis substantiated the flow cytometry results. The efficient cellular entry of labeled siRNA in GFP expressing cells as evidenced from confocal microscopy put forward these gemini lipids among the potent lipidic carriers for siRNA. The efficient transfection capabilities were also profiled in a more relevant fashion while performing siRNA transfections against survivin (an anti-apoptotic protein) which induced substantial apoptosis. Furthermore, the survivin downregulation improved the therapeutic efficacy levels of an anticancer drug, doxorubicin, significantly. In short, the new tocopherol based gemini lipids appear to be highly promising for achieving siRNA mediated gene knockdown in various cell lines.

Remarkable visible light-triggered cytotoxicity of mitochondria targeting mixed-ligand cobalt(III) complexes of curcumin and phenanthroline bases binding to human serum albumin

Six new mixed-ligand cobalt(III) complexes of formulation Co(N-N)(2)(O-O)](ClO4)(2) (1-6), where N-N is a N,N-donor phenanthroline base, namely, 1,10-phenanthroline (phen in 1, 2), dipyrido3,2-d:2',3'-f] quinoxaline (dpq in 3, 4), and dipyrido3,2-a:2',3'-c]phenazine (dppz in 5, 6), O-O is acetylacetonate (acac in 1, 3, 5) or curcumin (bis(4-hydroxy-3-methoxyphenyl)-1,6-diene-3,5-dione, cur in 2, 4, 6), have been synthesized and characterized. The X-ray crystal structures of complex 1 (as PF6- salt, 1a) and 3 show distorted octahedral geometries formed by the CoN4O2 core. The complexes 1, 3 and 5 having the simple acac ligand are prepared as control species to understand the role of curcumin. The optimized geometries and the frontier orbitals of the curcumin complexes 2, 4, and 6 are obtained from the DFT calculations. The complexes 2, 4, and 6 having the photoactive curcumin moiety display an absorption band in the visible region near 420 nm and show remarkable photocytotoxicity in HeLa cancer cells with respective IC50 values of 7.4 mu M, 5.1 mu M and 1.6 mu M while being much less toxic in dark. MTT assay using complex 6 shows that it is not significantly photocytotoxic to MCF-10A normal cells. The control complexes having the acac ligand are non-toxic both in the presence and absence of light. The cell death is apoptotic in nature and triggered by the photogeneration of reactive oxygen species. Fluorescence imaging experiments on HeLa cells reveals that complex 6 accumulated primarily inside the mitochondria. Human serum albumin (HSA) binding experiments show that the complexes bind HSA with good affinity, but 6 binds with the highest affinity, with a K-b value of 9.8 x 10(5) M-1. Thus, complex 6 with its negligible toxicity in the dark and in normal cells but remarkable toxicity in visible light holds significant photochemotherapeutic potential.

Effect of oxygen vacancies on the elastic properties of zinc oxide: A first-principles investigation

The effect of oxygen vacancies on the elastic properties of zinc oxide (ZnO) is examined using first-principles calculations based on density functional theory. Formation energies of vacancies in different types of oxygen deficient structures were analyzed to ascertain their stability. This analysis reveals that the doubly-charged oxygen vacancy under zinc-rich growth conditions is the most stable. Results show considerable degradation of some of the elastic moduli due to the presence of oxygen vacancies, which is in agreement with recent experiments. The decrease observed in elastic constants is more pronounced with increase in vacancy concentration. Further, the charge state of the defect structure was found to influence the shear elastic constants. Evaluation of elastic anisotropy of stoichiometric and oxygen deficient ZnO indicates the significant anisotropy in elastic properties and stiff c-axis orientation. (C) 2014 Elsevier B.V. All rights reserved.

Investigation on two magnon scattering processes in pulsed laser deposited epitaxial nickel zinc ferrite thin film

Ferromagnetic resonance (FMR) measurements are employed to evaluate the presence of the two magnon scattering contribution in the magnetic relaxation processes of the epitaxial nickel zinc ferrite thin films deposited using pulsed laser deposition (PLD) on the (0 0 1) MgAl2O4 substrate. Furthermore, the reciprocal space mapping reveals the presence of microstructural defects which acts as an origin for the two magnon scattering process in this thin film. The relevance of this scattering process is further discussed for understanding the higher FMR linewidth in the in-plane configuration compared to the out-of-plane configuration. FMR measurements also reveal the presence of competing uniaxial and cubic anisotropy in the studied films.

Co-liposomes of redox-active alkyl-ferrocene modified low MW branched PEI and DOPE for efficacious gene delivery in serum

Herein, we present six new lipopolymers based on low molecular weight, branched polyethylenimine (BPEI 800 Da) which are hydrophobically modified using ferrocene terminated alkyl tails of variable lengths. The effects of degree of grafting, spacer length and the redox state of ferrocene in the lipopolymers on the self assembly properties were investigated in detail by TEM, AFM, DLS and zeta potential measurements. The assemblies displayed an oxidation induced increase in the size of the aggregates. The co-liposomes comprising the lipopolymer and a helper lipid, 1,2-dioleoyl phosphatidyl ethanolamine (DOPE), showed excellent gene (pDNA) delivery capability in a serum containing environment in two cancer cell lines (HeLa and U251 cells). Optimized formulations showed remarkably higher transfection activity than BPEI (25 kDa) and were also significantly better than a commercial transfection reagent, Lipofectamine 2000 as evidenced from both the luciferase activity and GFP expression analysis. Oxidation of ferrocene in the lipopolymers led to drastically reduced levels of gene transfection which was substantiated by reduced cellular internalization of fluorescently labelled pDNA as detected using confocal microscopy and flow cytometry. Moreover, the transfection inactive oxidized lipopolyplexes could be turned transfection active by exposure to ascorbic acid (AA) in cell culture medium during transfection. Endocytosis inhibition experiments showed that gene expression mediated by reduced formulations involved both clathrin and caveolae mediated pathways while the oxidized formulations were routed via the caveolae. Cytotoxicity assays revealed no obvious toxicity for the lipopolyplexes in the range of optimized transfection levels in both the cell lines studied. Overall, we have exploited the redox activity of ferrocene in branched PEI-based efficient polymeric gene carriers whose differential transfection activities could be harnessed for spatial or temporal cellular transfections.

Efficacious redox-responsive gene delivery in serum by ferrocenylated monomeric and dimeric cationic cholesterols

Herein, we present the design and synthesis of new redox-active monomeric and dimeric (gemini) cationic lipids based on ferrocenylated cholesterol derivatives for gene delivery. The cationic cholesterols are shown to be transfection efficient after being formulated with the neutral helper lipid DOPE in the presence of serum (FBS). The redox activity of the resulting co-liposomes and their lipoplexes could be regulated using the alkanyl ferrocene moiety attached to the ammonium head groups of the cationic cholesterols. Atomic force microscopy (AFM), dynamic light scattering (DLS) and zeta potential measurements were performed to characterize the co-liposomal aggregates and their complexes with pDNA. The transfection efficiency of lipoplexes could be tuned by changing the oxidation state of the ferrocene moiety. The gene transfection capability was assayed in terms of green fluorescence protein (GFP) expression using pEGFP-C3 plasmid DNA in three cell lines of different origins, namely Caco-2, HEK293T and HeLa, in the presence of serum. The vesicles possessing ferrocene in the reduced state induced an efficient transfection, even better than a commercial reagent Lipofectamine 2000 (Lipo 2000) as evidenced by flow cytometry and fluorescence microscopy. All the co-liposomes containing the oxidized ferrocene displayed diminished levels of gene expression. Gene transfection events from the oxidized co-liposomes were further potentiated by introducing ascorbic acid (AA) as a reducing agent during lipoplex incubation with cells, leading to the resumption of transfection activity. Assessment of transfection capability of both reduced and oxidized co-liposomes was also undertaken following cellular internalization of labelled pDNA using confocal microscopy and flow cytometry. Overall, we demonstrate here controlled gene transfection activities using redox-driven, transfection efficient cationic monomeric and dimeric cholesterol lipids. Such systems could be used in gene delivery applications where transfection needs to be performed spatially or temporally.

Oriented nanometric aggregates of partially inverted zinc ferrite: One-step processing and tunable high-frequency magnetic properties

In this work, it is demonstrated that the in situ growth of oriented nanometric aggregates of partially inverted zinc ferrite can potentially pave a way to alter and tune magnetocrystalline anisotropy that, in turn, dictates ferromagnetic resonance frequency (f(FMR)) by inducing strain due to aggregation. Furthermore, the influence of interparticle interaction on magnetic properties of the aggregates is investigated. Mono-dispersed zinc ferrite nanoparticles (<5 nm) with various degrees of aggregation were prepared through decomposition of metal-organic compounds of zinc (II) and iron (III) in an alcoholic solution under controlled microwave irradiation, below 200 degrees C. The nanocrystallites were found to possess high degree of inversion (>0.5). With increasing order of aggregation in the samples, saturation magnetization (at 5 K) is found to decrease from 38 emu/g to 24 emu/g, while coercivity is found to increase gradually by up to 100% (525 Oe to 1040 Oe). Anisotropy-mediated shift of f(FMR) has also been measured and discussed. In essence, the result exhibits an easy way to control the magnetic characteristics of nanocrystalline zinc ferrite, boosted with significant degree of inversion, at GHz frequencies. (C) 2015 AIP Publishing LLC.