Review on zirconate-cerate-based electrolytes for proton-conducting solid oxide fuel cell

The performance of low-to-intermediate temperature (400–800?°C) solid oxide fuel cells (SOFCs) depends on the properties of electrolyte used. SOFC performance can be enhanced by replacing electrolyte materials from conventional oxide ion (O^2-) conductors with proton (H⁺) conductors because H⁺ conductors have higher ionic conductivity and theoretical electrical efficiency than O^2- conductors within the target temperature range. Electrolytes based on cerate and/or zirconate have been proposed as potential H⁺ conductors. Cerate-based electrolytes have the highest H⁺ conductivity, but they are chemically and thermally unstable during redox cycles, whereas zirconate-based electrolytes exhibit the opposite properties. Thus, tailoring the properties of cerate and/or zirconate electrolytes by doping with rare-earth metals has become a main concern for many researchers to further improve the ionic conductivity and stability of electrolytes. This article provides an overview on the properties of four types of cerate and/or zirconate electrolytes including cerate-based, zirconate-based, single-doped cerate–zirconate and hybrid-doped cerate–zirconate. The properties of the proton electrolytes such as ionic conductivity, chemical stability and sinterability are also systematically discussed. This review further provides a summary of the performance of SOFCs operated with cerate and/or zirconate proton conductors and the actual potential of these materials as alternative electrolytes for proton-conducting SOFC application.     

The process window for diamond deposition from the vapor phase with sulfur in the C–H–O feed gas mixtures

Theoretical predictions using a modified radical species ternary diagram for C–H–O system indicate that addition of sulfur expands the C–H–O gas phase compositional window for diamond deposition. Sulfur addition to no-growth domain increases the carbon super-saturation by binding the oxygen and the addition of sulfur to the non-diamond domain reduces the heavy carbon super-saturation by decreasing C_nH_m species concentration in the gas phase. The overall effect of sulfur addition to gas phase mixtures is characterized as that of oxygen addition to the C–H system, i.e. expansion of the compositional window over which diamond can be deposited from the gas phase. In addition, the increasing sulfur concentration to diamond domain feed gases beyond 2000 ppm did not affect the steady state gas phase composition but the quality of diamond was reduced.     

Defensiveness, trait anxiety, and Epstein-Barr viral capsid antigen antibody titers in healthy college students.

Investigated the relationship of individual differences in repressive coping styles with differences in antibody titer to Epstein-Barr (EB) viral capsid antigen in a normal, healthy college population made up of people previously exposed to EB. Each of 54 1st-yr undergraduates completed a battery of physical-status questions and items pertaining to potential behavioral immunomodulatory confounds, along with the Taylor Manifest Anxiety Scale and the Marlowe-Crowne Social Desirability Scale. Ss reporting high and middle levels of anxiety had higher antibody titers to EB, suggesting poorer immune control over the latent virus, as compared with the low-anxious group. Similarly, high-defensive Ss had higher antibody titers than their low-defensive counterparts, and neither group differed from the middle group. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

RADIAL FLOW HOLLOW FIBERREVERSE OSMOSIS: EXPERIMENTS AND THEORY

The performance of a hollow fiber reverse osmosis system is studied both theoretically and experimentally. Experiments were carried out for applied pressure ranging from 200 to 400 psig, feed rates varying from 75 to 380 cc/sec and for feed concentrations up to 34,000 ppm of sodium chloride.

A mathematical model is proposed to predict productivity, ϕ, and product concentration, θ_p. The model involves solving membrane transport equations simultaneously with the hydrodynamic equations. The solubility-diffusion-imperfection, or pore diffusion model, is used to describe solute and solvent transport across the membrane. The axial gradients of shell side concentration, neglected in previous investigations, are taken into account. The differential equations are solved numerically by the 4th Order Runge-Kutta method.

Predicted values of ϕ and θ_p agree within 8% and 17% respectively, with experimental data over the entire range of operating conditions. However, membrane transport coefficients were found to be concentration dependent.

An approximate analysis shows that the concentration polarization is negligible in present day hollow fiber systems.     

Response of wheat (Triticum aestivum) and pearl-millet (Pennistum americanum) to zinc fertilizers on two soils

Responses of ZnSO₄, Zn₃ (PO₄)₂ · 4H₂O, ZnO, ZnNH₄PO₃ · 2H₂O and zincated superphosphate were studied on wheat (Triticum aestivum) and pearl-millet (Pennistem americanum) in Balsamand sand (Ustipsament) and Ladwa fine loam (Typic Camborthids). In Balsamand sand all Zn fertilizers increased wheat and pearl-milllet grain yield significantly over control but ZnNH₄ PO₄ · 2H₂O and zincated super were the best sources. Straw yield was also highest due to zincated super and ZnNH₄PO₄ · 2H₂O applications. Zinc sulphate was significantly inferior to zincated super and ZnNH₄PO₄ · 2H₂O. In Ladwa fine loam, all fertilizers gave significantly higher grain yield of wheat and pearl-millet than control except ZnO in pearl-millet. Highest yield in this soil was obtained by ZnSO₄ · 7H₂O followed by ZnNH₄ PO₄ · 2H₂O and then zincated super.In Balsamand sand, the Zn fertilizers significantly increased the Zn concentration and Zn uptake of wheat grain. In pearl-millet, only Zn uptake was increased significantly with Zn fertilizers. Zincated super gave highest Zn uptake.The concentration of P in wheat grain was increased by Zn fertilizers in Balsamand sand, and also in pearl-millet where zincated super and ZnNH₄PO₄ were most effective in increasing the P content.When Zn fertilizers were applied to preceding pearl-millet the effect on succeeding wheat crop were in the same order as direct application of Zn fertilizers. Zincated super was the best and ZnO worst with respect to wheat grain and straw yield and uptake of Zn and P.     

Biosynthesis of zinc oxide nanoparticles by petals extract of Rosa indica L., its formulation as nail paint and evaluation of antifungal activity against fungi causing onychomycosis

Aim: The authors report the biological synthesis of zinc oxide nanoparticles (ZnO‐NPs) from the petals extract of Rosa indica L. (rose). Its efficacy was evaluated against two dermatophytes: namely: Trichophyton mentagrophytes and Microsporum canis which cause onychomycosis. The activity of antibiotics against the tested dermatophytes was enhanced, when evaluated in combination with ZnO‐NPs. Methods and results: The synthesised ZnO‐NPs were preliminary detected by using ultraviolet UV visible spectroscopy, which showed specific absorbance. The ZnO‐NPs were further characterised by nanoparticle tracking analysis (NTA), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X‐ray diffraction and Zetasizer. Moreover, nanoparticles containing nail paint (nanopaint) was formulated and its antifungal activity was also assessed against T. mentagrophytes and M. canis. ZnO‐NPs and formulated nanopaint containing ZnO‐NPs, both showed significant antifungal activity. The maximum activity was noted against M. canis and lesser against T. mentagrophytes. Minimum inhibitory concentration of ZnO‐NPs was also determined against the dermatophytes causing onychomycosis infection. Conclusion: ZnO‐NPs can be utilised as a potential antifungal agent for the treatment of onychomycosis after more experimental trials.Inspec keywords: diseases, zinc compounds, nanoparticles, nanofabrication, antibacterial activity, microorganisms, nanomedicine, ultraviolet spectra, visible spectra, Fourier transform infrared spectra, transmission electron microscopy, X‐ray diffraction, biomedical materials, patient treatmentOther keywords: zinc oxide nanoparticle biosynthesis, Rosa indica L petals extract, nail paint, antifungal activity evaluation, dermatophyte, Trichophyton mentagrophytes, Microsporum canis, antibiotics activity, ultraviolet‐visible spectroscopy, nanoparticle tracking analysis, Fourier transform infrared spectroscopy, transmission electron microscopy, X‐ray diffraction, zetasizer, antifungal agent, onychomycosis treatment     

Biogenic copper nanoparticles promote the growth of pigeon pea (Cajanus cajan L.)

Environmental pollution and toxicity have been increasing due to the overuse of chemical fertilisers, which has encouraged nanotechnologists to develop eco‐friendly nano‐biofertilisers. The authors demonstrated the effect of biogenic copper nanoparticles (CuNPs) on the growth of pigeon pea (Cajanus cajan L.). The UV–visible analysis showed absorbance at 615 nm. Nanoparticle tracking and analysis revealed particle concentration of 2.18 × 10⁸ particles/ml, with an average size of 33 nm. Zeta potential was found to be −16.7 mV, which showed stability. X‐ray diffraction pattern depicted the face centred cubic structure of CuNPs; Fourier transform infrared spectroscopy demonstrated the capping due to acidic groups, and transmission electron micrograph showed nanoparticles with size 20–30 nm. The effect of CuNPs (20 ppm) on plant growth was studied, for the absorption of CuNPs by plants on photosynthesis, which was evaluated by measuring chlorophyll a fluorescence using Handy‐Plant Efficiency Analyser. CuNPs treatment showed a remarkable increase in height, root length, fresh and dry weights and performance index of seedlings. The overall growth of plants treated with CuNPs after 4 weeks was recorded. The results revealed that inoculation of CuNPs contribute growth and development of pigeon pea due to growth promoting activity of CuNPs.Inspec keywords: pollution, toxicology, nanotechnology, cropsOther keywords: biogenic copper nanoparticles, pigeon pea, Cajanus cajan L, environmental pollution, toxicity, chemical fertilisers, nanotechnologists, eco‐friendly nano‐biofertilisers, cash crop, UV‐visible analysis, nanoparticle tracking, zeta potential, X‐ray diffraction pattern, Fourier transform infrared spectroscopy, acidic groups, transmission electron micrograph, photosynthesis, chlorophyll, fluorescence, Handy‐Plant Efficiency Analyser, performance index     

Efficacy of biogenic silver nanoparticles against clinical isolates of fungi causing mycotic keratitis in humans

Mycotic keratitis is mainly responsible for vision loss caused by various fungi. Sometimes, proper treatment of such infection is not possible due to unavailability of effective antifungal agents and development of resistance of such fungi to antimycotic drugs. Hence, it is necessary to search for potential antifungal agents, which can effectively eradicate fungal infection of eyes. Nanoparticles‐based antifungal drugs overcome this problem by increasing permeability and properties of drug molecules. In the present study, silver nanoparticles were synthesised by using Helminthosporium sp. and Chaetomium sp. following sequential reduction technique. The synthesised silver nanoparticles were detected primarily by UV‐visible spectrophotometer showing absorption spectra at 424 and 433 nm, respectively. Nanoparticles tracking analysis confirmed the mean particle size of silver nanoparticles as 45 and 55 nm. The synthesised AgNPs showed significant antifungal activity against fungi causing mycotic keratitis, when used alone and in combination with ketoconazole and amphotericin B in the range of 30–70 microgram per millilitre of minimum inhibitory concentration. Thus, the synthesised AgNPs can be used to enhance the activities of ketoconazole and amphotericin B.Inspec keywords: silver, nanoparticles, nanomedicine, antibacterial activity, diseases, permeability, ultraviolet spectra, visible spectra, particle sizeOther keywords: biogenic silver nanoparticles, fungi, mycotitic keratitis, vision loss, infection, antifungal agents, antimycotic drugs, antifungal drugs, permeability, Helminthosporium sp, Chaetomium sp, sequential reduction technique, UV‐visible spectrophotometer, mean particle size, ketoconazole, amphotericin B, wavelength 424 nm, wavelength 433 nm, size 45 nm, size 55 nm, Ag     

A compact printed multistubs loaded resonator rectangular monopole antenna design for multiband wireless systems

In the present article, a compact triple‐band multistubs loaded resonator printed monopole antenna is proposed. The antenna consists of a quarter wavelength two asymmetrical inverted L‐shaped stubs to excite two resonant modes for 3.5/5.5 GHz bands and one integrated horizontally T‐shaped stub with inverted long L‐shaped stub to excite resonant mode for 2.5 GHz band. By loading these stub resonators along y‐axis with distinct gaps, the antenna resonates at three frequencies 2.57/3.52/5.51 GHz covering the desired bands while keeping compact size of 24 × 30 mm² (0.2 × 0.25 ). The proposed antenna is fabricated on Rogers RT/duroid 5880 substrate with thickness 0.79 mm and its performance experimentally verified. The measured results reveal that the antenna has the impedance bandwidths of about 210 MHz (2.50‐2.71 GHz), 260 MHz (3.37‐3.63 GHz), and 650 MHz (5.20‐5.85 GHz), for 2.5/3.5/5.5 GHz WiMAX and 5.2/5.8 GHz WLAN band systems. The antenna provides omnidirectional radiation patterns and flat antenna gains over the three operating bands. In addition, the design approach and effects of multistubs resonator lengths on the operating bands are also examined and discussed in detail.