Reduction In Presence Research Articles

Para-nitrophenol reduction on solvothermally prepared cobalt@silica core–shell catalysts

Cobalt supported solids on silica have been prepared as core–shell nanocomposites and via a classical impregnation of commercial and prepared silica. The solids have been characterized by AAS, XRD, N2 adsorption–desorption, UV–Vis spectroscopy and SEM–EDX techniques. The catalytic activity of the solids was probed in the p-nitrophenol reduction in presence of NaBH4. The core–shell solid presented small particle size, high specific surface area, good cobalt dispersion and small gap energy value. All these characteristics contribute to improving the catalytic performance of this solid compared to the solids prepared via silica impregnation and containing the same amount of cobalt.

Aeromonas hydrophila-induced alterations in cytosolic calcium activate pro-apoptotic cPKC-MEK1/2-TNFα axis in infected headkidney macrophages of Clarias gariepinus

Alterations in intracellular-calcium (Ca2+)i homeostasis is critical to Aeromonas hydrophila-induced headkidney macrophages (HKM) apoptosis of Clarias gariepinus, though the implications are poorly understood. Here, we describe the role of intermediate molecules of Ca2+−signaling pathway that are involved in HKM apoptosis. We observed phosphoinositide-3-kinase/phospholipase C is critical for (Ca2+)i release in infected HKM. Heightened protein kinase-C (PKC) activity and phosphorylation of MEK1/2-ERK1/2 was noted which declined in presence of 2-APB, Go6976 and PD98059, inhibitors to IP3-receptor, conventional PKC isoforms (cPKC) and MEK1/2 respectively implicating Ca2+/cPKC/MEK-ERK1/2 axis imperative in A. hydrophila-induced HKM apoptosis. Significant tumor necrosis factor-α (TNFα) production and its subsequent reduction in presence of MEK-ERK1/2 inhibitor U0126 suggested TNFα production downstream to cPKC-mediated signaling via MEK1/2-ERK1/2 pathway. RNAi and inhibitor studies established the role of TNFα in inducing caspase-8-mediated apoptosis of infected HKM. We conclude, alterations in A. hydrophila-induced (Ca2+)i alterations activate cPKC-MEK1/2-ERK1/2-TNFα signaling cascade triggering HKM apoptosis.

An adjoint-based hp-adaptive stabilized finite-element method with shock capturing for turbulent flows

In this study, an adjoint-based hp-adaptation algorithm has been developed within a Petrov–Galerkin finite-element method. The developed mesh adaptation algorithm is able to perform non-conformal mesh adaptations. To account for hanging nodes in a consistent manner, the constrained approximation method has been utilized. Hierarchical basis functions have been employed to facilitate the implementation of the constrained approximation. The methodology has been demonstrated on numerous cases using the Euler and Reynolds Average Navier–Stokes (RANS) equations, equipped with negative variant of Spalart–Allmaras (SA) turbulence model. Also, a PDE-based artificial viscosity has been added to the governing equations, to stabilize the solution in the vicinity of shock waves. For accurate representation of the geometric surfaces, high-order curved boundary meshes have been generated and the interior meshes have been deformed through the solution of a modified linear elasticity equation. Fully implicit linearization has been used to advance the solution toward a steady-state. Dirichlet boundary conditions have been imposed weakly and the functional outputs have been modified according to the weak boundary conditions in order to provide a smooth adjoint solution near the boundaries. To accelerate the error reduction in presence of singularity points, an enhanced h-refinement, based on solution’s smoothness, has been used. Numerical results illustrate consistent accuracy improvement of the functional outputs for both h- and hp-adaptation, and also capability enhancement in capturing complex viscous effects such as shock-wave/turbulent boundary layer interaction.

Metallogel templated synthesis and stabilization of silver-particles and its application in catalytic reduction of nitro-arene

Metallogel of iron-carboxylates was obtained from trans-1,2-cyclohexanedicarboxylic acid in dimethylformamide (DMF) at basic condition. Spectroscopic and SEM morphology study of the iron-metallogel revealed that the iron complex with dicarboxylic acid was linked together via carboxylates and led to a supramolecular helical like architecture. The synthesized metallogel served as an excellent template for in-situ reduction of silver ion to silver particles micro to nano scale range. Variation of AgNO3 concentration shepherd to change the morphology of the Ag-particles. AgNO3 concentration was found to affect the shape and size of silver particles. On going from lower to higher concentration shape of silver particles changed from spherical to large agglomerated particles. Cubic shape Ag-particles were found on treatment of 0.05M AgNO3 solution with metallogel. Cubical shape silver particles were found to be effective catalyst for nitro-arene reduction in presence of NaBH4. Density functional theory (DFT) calculations were performed to rationalize the role of Ag-particles in catalytic reduction of 4-nitrophenol to 4-aminophenol. Based on DFT study, we proposed that catalytic reduction occurred via Ag-hydride complex formation. Since metallogels as well as the 4-aminophenol are finding large application in pharmaceuticals industries therefore the current work can provide an alternatives path in production of 4-aminophenols. In addition to this, the synthesis of Ag-nanomaterials using metallogel as template can pave a new direction in the development of nanotechnology and might find wide applications in catalytic industrial processes.

Comparing ranibizumab monotherapy and combination with single photodynamic therapy in wet AMD: retreatment and morphologic results.

To evaluate retreatment indications/morphologic responses to ranibizumab monotherapy and combination with verteporfin photodynamic therapy (PDT). A total of 40 patients received 3 monthly intravitreal ranibizumab 0.3 mg injections combined with either PDT or sham PDT at baseline (1:1) followed by as-needed ranibizumab based on predetermined vision/anatomical criteria. Retreatment criteria were visual acuity (VA) loss (59%/58%), central retinal thickness (CRT) increase (27%/26%), or both (14%/16%). One month before retreatment, intraretinal cysts (IRC) were present in 84%/74%, subretinal fluid (SRF) in 70%/63%, and at least one of them in 84%/89% of eyes. A significant decrease in mean leakage area, IRC, and SRF as well as a reduction in presence of hemorrhages and hard exudates occurred in both treatment groups at 12 months (compared to baseline). Retreatment indications were mostly based on VA loss, probably due to the quantitative optical coherence tomography criterion. Intraretinal cysts and SRF were earlier predictors for recurring choroidal neovascularization (CNV) activity than CRT/VA changes. Both treatment strategies were equally potent in reducing CNV activity.

Adherence to a Mediterranean diet is associated with lower prevalence of osteoarthritis: Data from the osteoarthritis initiative.

The Mediterranean diet appears to be beneficial for several medical conditions, but data regarding osteoarthritis (OA) are not available. The aim of this study was to investigate if adherence to the Mediterranean diet is associated with a lower prevalence of OA of the knee in a large cohort from North America. 4358 community-dwelling participants (2527 females; mean age: 61.2 years) from the Osteoarthritis Initiative were included. Adherence to the Mediterranean diet was evaluated through a validated Mediterranean diet score (aMED) categorized into quartiles (Q). Knee OA was diagnosed both clinically and radiologically. The strength of the association between aMED (divided in quartiles) and knee OA was investigated through a logistic regression analysis and reported as odds ratios (ORs) with 95% confidence intervals (CIs), adjusted for potential confounders. Participants with a higher adherence to Mediterranean diet had a significantly lower prevalence of knee OA compared to those with lower adherence (Q4: 25.2% vs. Q1: 33.8%; p<0.0001). Using a logistic regression analysis, adjusting for 10 potential confounders with those in the lowest quartile of aMED as reference, participants with the highest aMED had a significant reduction in presence of knee OA (OR, 0.83; 95% CIs: 0.69-0.99, p=0.04). Among the individual components of Mediterranean diet, only higher use of cereals was associated with lower odds of having knee OA (OR: 0.76; 95%CI: 0.60-0.98; p=0.03). Higher adherence to a Mediterranean diet is associated with lower prevalence of knee OA. This remained when adjusting for potential confounders.

Effect of organic by-products amendments on quality of heavy metal-contaminated soil treated using aided phytostabilization

In organic farming it is crucial to reach the best compromise between yield and sustainability of agronomical strategies. To this end, this two-year study evaluated the effects of legume cover crop management (no cover; vetch grown as green manure; roller crimped vetch) and organic amendments (no fertilizer; compost; animal manure; digestate fertilizer) application on organic transplanted zucchini and weed biomass productions, N dynamics, N balance and competitive interactions. In the first year, the vetch incorporated as green manure treatment showed the highest zucchini yield and weed biomass, as well as the highest crop N uptake reduction in presence of weeds. The roller crimped cover crop showed a decrease in weed biomass by more than 65% compared to green manure, and higher productivity than the no cover treatment. Animal manure and digestate fertilizers showed the highest yield, soil mineral N contents and crop N uptake, even if no variation in competitive ability was recorded. Conversely, the second year showed the potential limits of the roller crimping technique under cooler conditions, implying a reduction in zucchini yield performances and competitive ability. Among the experimental fertilizers, the digestate showed comparable results than commercial fertilizer for yield, but significantly higher than N0 (by 31%) and, when combined to vetch management, also in terms of N balance. This study illustrates the effectiveness of combination of different agronomical strategies to obtain adequate yield and weed impact reduction.

Chronopotentiometric study of a Nafion membrane in presence of glucose

Chronopotentiometric and swelling experiments have been conducted to characterize the behavior of a Nafion membrane in NaCl and KCl aqueous solutions without and with glucose. A mixture solution with similar composition to the cerebrospinal fluid and blood plasma has also been studied. From the chronotentiograms, current-voltage curves have been obtained, and the values of the limiting current density, diffusion boundary layer thickness, difference between counter-ion transport number in membrane and free solution, and transition times have been determined for the investigated membrane systems. The obtained results indicate that the presence of glucose affects the ion transport through the membrane depending on the electrolyte and glucose concentrations. At low electrolyte concentration, experimental transition times are found to be smaller in presence of glucose, which has been related to an effective membrane area reduction in presence of glucose. The membrane system corresponding to the mixture solution shows a behavior similar to the single high concentration NaCl membrane system, indicating that the observed behavior is mainly associated to the Na+ ions transport in higher proportion. In this case, the glucose presence does not affect significantly the investigated properties of the membrane, which is interesting for its utilization in a glucose fuel cell.

Automated cytochrome c oxidase bioassay developed for ionic liquids’ toxicity assessment

A fully automated cytochrome c oxidase assay resorting to sequential injection analysis (SIA) was developed for the first time and implemented to evaluate potential toxic compounds. The bioassay was validated by evaluation of 15 ionic liquids (ILs) with distinct cationic head groups, alkyl side chains and anions. The assay was based on cytochrome c oxidase activity reduction in presence of tested compounds and quantification of inhibitor concentration required to cause 50% of enzyme activity inhibition (EC50). The obtained results demonstrated that enzyme activity was considerably inhibited by BF4 anion and ILs incorporating non-aromatic pyrrolidinium and tetrabutylphosphonium cation cores. Emim [Ac] and chol [Ac], on contrary, presented the higher EC50 values among the ILs tested.The developed automated SIA methodology is a simple and robust high-throughput screening bioassay and exhibited good repeatability in all the tested conditions (rsd<3.7%, n=10). Therefore, it is expected that due to its simplicity and low cost, the developed approach can be used as alternative to traditional screening assays for evaluation of ILs toxicity and identification of possible toxicophore structures. Additionally, the results presented in this study provide further information about ILs toxicity.

Piper betle leaf extract affects the quorum sensing and hence virulence of Pseudomonas aeruginosa PAO1

Quorum sensing (QS) plays an important role in virulence of Pseudomonas aeruginosa, blocking of QS ability are viewed as viable antimicrobial chemotherapy and which may prove to be a safe anti-virulent drug. Bioactive components from Piper betle have been reported to possess antimicrobial ability. This study envisages on the anti-QS properties of ethanolic extract of P. betle leaf (PbLE) using P. aeruginosa PAO1 as a model organism. A marked reduction in swarming, swimming, and twitching ability of the bacteria is demonstrated in presence of PbLE. The biofilm and pyocyanin production also shows a marked reduction in presence of PbLE, though it does not affect the bacterial growth. Thus, the studies hint on the possible effect of the bioactive components of PbLE on reducing the virulent ability of the bacteria; identification of bioactive compounds should be investigated further.Electronic supplementary materialThe online version of this article (doi:10.1007/s13205-015-0348-8) contains supplementary material, which is available to authorized users.

A nitrogen-doped graphene electrocatalyst for selective oxygen reduction in presence of glucose and D-gluconic acid in pH-neutral media

The development of high-active, selective and low-cost electrocatalysts for oxygen reduction reaction (ORR) is of major interest for catalysis in fuel cells. In this article, we present various nitrogen-doped graphenes as high performance non-metal electrocatalysts for ORR based on graphene thermally treated with cyanamide. The impact of treatment temperature on the structure and ORR performance of prepared samples is systematically investigated. Obtained results indicate that electrochemically active surface area (ECSA) and electrocatalytic ORR activity at both neutral and alkaline conditions are enhanced for samples treated at higher temperatures showing a clear correlation between ECSA and ORR activity. A comparison of determined ORR performances with XPS results demonstrates that not the total quantity of nitrogen improves ORR activity, but we think that optimum content of graphitic nitrogen functionality is mainly responsible for the improved electrocatalytic performance. The main novelties of our work are specifically the voltammetric studies of the ORR mechanism on prepared nitrogen-doped graphene and the investigation of the electrocatalytic activity in presence of glucose and D-gluconic acid in pH-neutral medium. We ascertained superior tolerance of nitrogen-doped graphene towards D-gluconic acid poisoning as well as glucose oxidation. Especially, the sample prepared at 1000°C exhibits improved electrocatalytic ORR performance compared to graphene-based materials, and significantly enhanced long-term operation stability, D-gluconic acid and glucose tolerance than commercial Pt/C, thus, perfectly suited for use in single-compartment glucose-based fuel cells operating at pH-neutral conditions.

A copper(II) complex as selective turn-on fluorosensor for nitric oxide and its intracellular application

A highly water soluble copper(II) complex, 1 of a fluorophore ligand 4-(2-hydroxybenzylamino)-5-hydroxynaphthalene-2,7-disulfonic acid (FL1) was synthesized and characterized. In the complex, the fluorescence intensity of the ligand was found to quench due to the presence of paramagnetic Cu(II) center. In degassed methanol solution of complex 1, the Cu(II) center was found to undergo reduction in presence of nitric oxide. This resulted in the simultaneous formation of N-nitrosated ligand. In the process, the quenched fluorescence intensity of the ligand restored. The selective turn on fluorogenic nature of the complex 1 was used to study the endogenously produced NO in living cells.

Tunable synthesis of platinum nanoparticles by EtOH reduction in presence of poly (vinylpyrrolidone)

Monodispersed platinum nanoparticles (Pt-NPs) with an average diameter dTEM 3.1±1.0 nm were synthesized by EtOH reduction method in the presence of an organic polymer poly (vinylpyrrolidone) (PVP) with an average molecular weight of 40,000. Using this particles as seed, size tunable Pt-NPs of dTEM 3.1±1.0 nm to 5.7±1.6 nm with sufficient monodispersity were synthesized by multiple step seeding growth. Formation of Pt-NPs was confirmed by the UV-visible absorption spectra. Transmission electron micrographs (TEM) and powder X-ray diffraction (XRD) patterns confirmed that the particles were single crystalline with fcc crystal geometry.Bangladesh J. Sci. Ind. Res. 50(2), 87-92, 2015

Impact of Thiourea Addition on Morphological and Structural Characteristics of Electrodeposited ZnO Thin Films Using Nitrate Aqueous Solutions

ZnO layers have been deposited on SnO2:F and ZnO:Al substrates via nitrate ions reduction in the presence of thiourea. First, a thermochemical study has been performed to determine the proportions of the free zinc ions and to calculate the Gibbs free energy of reaction. Then, the effect of thiourea concentration between 0 and 1.0 M on the nitrate reduction in presence of zinc ion has been investigated by cyclic voltammetry in order to find the optimal potential for electrodeposition. The electrodeposited films have been characterized by Scanning Electron Microscopy, X-Ray Diffraction Spectroscopy and Energy Dispersive X-ray Spectroscopy. These analyses highlight that the deposited films are composed of well-crystallized ZnO presenting wurtzite type structure with no sulfur incorporation. The morphology of the layers depends both on the substrate and the thiourea concentration. Moreover, the apparent Faradaic efficiency calculations show that the thiourea addition results in an increase of values above 1.

Study of behaviour of aluminium oxide nanoparticles suspended in SAE20W40 oil under extreme pressure lubrication

Purpose – The purpose of this paper is to include investigation on extreme pressure lubrication behaviour of Al2O3 nanoparticles suspended in SAE20W40 lubricating oil. Effects of nanoparticles size (40-80 nm) and its concentration (0-1 per cent) on the coefficient of friction is studied using pin-on-disc tribotester. Design/methodology/approach – Taguchi technique is used to optimize the process parameters for lower coefficient of friction. L18 orthogonal array involving six levels for one factor and three levels for remaining three factors is selected for the experimentation. The parameters selected for the study are sliding speed, normal load, nanoparticles size and its concentration in base oil. Findings – It has been found that the presence of nanoparticles in proper concentration shows excellent tribological improvement in frictional characteristics compared to the base oil. The optimal combination of the parameters for minimum coefficient of friction is found to be 0.8 per cent concentration of 60 nm sized Al2O3 nanoparticles, 1,200 rpm sliding speed and 160 N of normal load. The mechanism of friction reduction in presence of nanoparticles is investigated using scanning electron microscopy. Originality/value – This is the original work.

Investigation of Photoelectrochemical Deposition of Zn(S,O) Via Nitrate Ions Reduction in the Presence of Thiourea

In this study, ZnO nanoporous layers have been deposited on Glass/Mo/Cu(In,Ga)Se2 substrate via nitrate ions reduction in presence of thiourea. The photoelectrochemical behavior of p-type semi-conductor Copper Indium Gallium Diselenide (CIGSe) has been studied in acidic medium for different pH values and different light intensities. Then, the effect of thiourea concentration between 0 and 1.0 M on the nitrate reduction in presence of zinc ion has been investigated by cyclic voltammetry in order to find the optimal potential for photoelectrodeposition. Results show that thiourea impacts the resulting photocurrent and the potential of the nitrates reduction. The photoelectrodeposited films have been characterized by Scanning Electron Microscopy, X-Ray Diffraction and X-Ray Photoelectron Spectroscopy. These analyses highlight that thiourea addition causes a change in film morphology, which is composed of well-crystallized ZnO with no sulfur incorporation. Moreover, thiourea seems to be an interesting additive to obtain nanoporous ZnO films on CIGSe.

Structural sensitivity of mesoporous alumina for copper catalyst loading used for NO reduction in presence of CO

Copper oxide supported on mesoporous alumina pre-treated at different temperatures was examined for catalytic reduction (SCR) of NO with CO. About 4.5% copper oxide was loaded on mesoporous alumina using wet impregnation method. Detailed investigations concluded that the activity of Cu/m-Al2O3 is strongly influenced by the active Cu phase present on bulk copper aluminate. The Copper phase on the catalyst was strongly affected by pre-treatment temperature of the host material. The optimal pre-treatment temperature of the support was found to be around 900°C. The reaction mechanism on the catalyst surface was suitably described using L-H mechanistic model with the reduced Cuδ+ sites generated on the catalyst surface post CO oxidation playing a critical role in NO reduction.

Synthesis, characterization and DFT studies of 1, 1′-Bis(diphenylphosphino)ferrocene substituted diiron complexes: Bioinspired [FeFe] hydrogenase model complexes

The reaction of [Fe2(CO)6(μ-toluene-3, 4-benzenedithiolate)] 1 and bidentate diphosphine, 1, 1′-bis(diphenylphosphino)ferrocene (dppf) has been studied. New complexes obtained have been characterized by various spectroscopic techniques as bioinspired models of the iron hydrogenase active site. The crystal structure of [Fe2(CO)5(κ 1-dppfO)(μ-toluene-3, 4-benzenedithiolate)] 4 is reported. New iron carbonyl complexes were synthesized from the reaction of [Fe2(CO)6(μ-toluene-3, 4-benzenedithiolate)] 1 and bidentate diphosphine, 1, 1’-bis(diphenylphosphino)ferrocene (dppf). Complex 2 was catalytically active towards proton reduction in presence of acetic acid. Based on DFT calculations the HOMO and LUMO in complex 2 were found to be localized on the Fe centers of the two {Fe2S2} units.

The Effects of (-)-Epigallocatechin-3-Galate on Wound Closure and Infections in Mice

In this study, we investigated the effects of (-)-epigallocatechin-3-gallate (EGCG) on wound healing both in vitro and in vivo with and without infection. EGCG has antimicrobial properties and could be useful as a topical agent to prevent and/or treat wound infections. Normal fibroblasts were isolated from the dermis of C57BL/6 mice and cultured with 0, 0.001 to 0.400 mg/ml of EGCG. In vitro assays demonstrated that migration, proliferation, and apop- tosis were inhibited at EGCG concentrations of 0.100-0.400 mg/ml. Expression of α-smooth muscle actin (α-SMA) was also reduced. In vivo experiments measured closure/contraction of full-thickness dorsal wounds that were treated with 0, 0.3, 3.0, and 30.0 mg/ml of EGCG every 24 hours. Macrophages (F4/80), neutrophils (Ly-6G) and myofibroblasts (α-SMA) were assessed at 48 and 168 hours. By 168 hours there was a significant reduction in presence with the 30 mg/ml dose vs. 0.3 and 3.0 mg/ml (P<0.009, P<0.006, respectively). The percentage of wound closure at one week in EGCG treated wounds was 87.87% (0.03 mg), 85.23% (0.3 mg) and 40.06% (30 mg/ml) compared to controls. Reduced quantities of α-SMA myofibroblasts were observed in the 3 mg EGCG treatment group compared to controls at 168 hours. We previously demonstrated that EGCG has antimicrobial properties (MIC 50 ~0.3 mg/ml). This data suggests that EGCG could potentially be applied to the wound surface as an antimicrobial without negatively influencing healing. To this end we applied EGCG (10 mg/ml) to a model of an infected traumatic wound. EGCG treatment significantly reduced bacterial load after one and two dose regimens.

Legume cover crop management and organic amendments application: Effects on organic zucchini performance and weed competition

In organic farming it is crucial to reach the best compromise between yield and sustainability of agronomical strategies. To this end, this two-year study evaluated the effects of legume cover crop management (no cover; vetch grown as green manure; roller crimped vetch) and organic amendments (no fertilizer; compost; animal manure; digestate fertilizer) application on organic transplanted zucchini and weed biomass productions, N dynamics, N balance and competitive interactions. In the first year, the vetch incorporated as green manure treatment showed the highest zucchini yield and weed biomass, as well as the highest crop N uptake reduction in presence of weeds. The roller crimped cover crop showed a decrease in weed biomass by more than 65% compared to green manure, and higher productivity than the no cover treatment. Animal manure and digestate fertilizers showed the highest yield, soil mineral N contents and crop N uptake, even if no variation in competitive ability was recorded. Conversely, the second year showed the potential limits of the roller crimping technique under cooler conditions, implying a reduction in zucchini yield performances and competitive ability. Among the experimental fertilizers, the digestate showed comparable results than commercial fertilizer for yield, but significantly higher than N0 (by 31%) and, when combined to vetch management, also in terms of N balance. This study illustrates the effectiveness of combination of different agronomical strategies to obtain adequate yield and weed impact reduction.