Battery storage in developing countries: Key issues to consider

There has been significant excitement around deployment of grid-connected battery storage around the world including many developing countries. As the cost of battery storage followed the sharp drop in solar and wind, batteries hold immense possibility to transform the power systems in the developing world. However, it will require great care in assessing the specific benefits that a battery storage can provide to the power system as a whole, and developing a business model based on a sound economic analysis. The latter assumes special significance in developing countries where electricity markets are yet to be fully developed in most cases, leaving it to the centralized planning process to undertake such cost-benefit analysis.     

Horizontal advection of temperature and salinity by Rossby waves in the North Pacific

The Aquarius satellite has been used for the first time to characterize Rossby waves in sea surface salinity (SSS) measurements for the North Pacific Ocean. Westward propagating wave signals are delineated by the SSS zonal salinity gradients. The phase velocities and spectral properties obtained from zonal salinity gradients are closely correlated with corresponding values obtained from the sea surface temperature (SST) zonal gradient and the altimetry-derived meridional velocity. The westward propagating SSS signals are consistent with Rossby wave advection across the strong meridional gradients of water characteristics. Following Killworth, we attempted to provide satellite-based estimates of the contribution of horizontal Rossby wave advection to the surface transfer of temperature and salinity in the North Pacific Ocean. Westward propagating signals in the SST and SSS zonal gradient fields show that the observed intensity of meridional advection by the ambient gradients of SST and SSS is less than the intensity predicted by an analytical solution of the transfer equation for Rossby waves. Our results extend the previous studies of physical mechanisms of Rossby wave manifestation at the sea surface and we demonstrate that Rossby waves are responsible for low-frequency oscillations in SST and SSS concentration in the North Pacific.     

Nearshore benthic blooms of filamentous green algae in Lake Baikal

For the first time, species of the genus Spirogyra, non-typical of the open nearshore waters of Lake Baikal, formed algal mats with Ulothrix zonata, Ulothrix tenerrima, and Ulothrix tenuissima near the village of Listvyanka, Russia. Normally widely distributed in the 0- to 1.5-m depth range, the growth of U. zonata was now evident and dominant (63% of the biomass) in the 2- to 5-m depth range. The overgrowth of the lake bottom by filamentous green algae, changes in distributional boundaries, the emergence and mass development of species of the genus Spirogyra, the presence of the eutrophic diatom indicator Fragilaria capucina var. vaucheriae, elevated abundances of coliform bacteria, and elevated levels of nutrients suggest an early stage of cultural eutrophication in the nearshore of Lake Baikal near Listvyanka, a popular tourist destination. The unusual abundance of Fragilaria associated with the filamentous green algae consisted of long-ribbon colonies of F. capucina var. vaucheriae, a eutrophic species, wound around the filamentous green algae, enhancing the dense algae mats. Historically dominant species, such as Didymosphenia geminata, Tetraspora cylindrica var. bullosa, and Draparnaldioides baicalensis typically observed at deeper depths of Lake Baikal, are now subdominants or minor species in the nearshore along the shoreline near Listvyanka.     

Gold nanoparticles supported on ceria-modified mesoporous titania as highly active catalysts for low-temperature water-gas shift reaction

New gold catalytic system prepared on ceria-modified mesoporous titania (CeMTi) used as water-gas shift (WGS) reaction catalyst is reported. Mesoporous titania (MTi) was synthesized using surfactant templating method through a neutral [C₁₃(EO)₆–Ti(OC₃H₇)₄] assembly pathway. Ceria modifying additive was deposited on MTi by deposition precipitation (DP) method. Gold-based catalysts with different gold content (1–5 wt.%) were synthesized by DP of gold hydroxide on mixed metal oxide support. The supports and the catalysts were characterized by powder X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), N₂ adsorption analysis and temperature-programmed reduction (TPR). The catalytic behavior of the gold-based catalysts was evaluated in WGS reaction in a wide temperature range (140–300 °C) and at different space velocities and H₂O/CO ratios. The influence of gold content and particle size on the catalytic performance was investigated. The WGS activity of the new gold/ceria-modified mesoporous titania catalysts was compared with that of gold catalysts supported on simple oxides CeO₂ and mesoporous TiO₂, as well as gold/ceria-modified titania and reference catalyst Au/TiO₂ type A (World Gold Council). A high degree of synergistic interaction between ceria and mesoporous titania and a positive modification of structural and catalytic properties by ceria has been achieved. It is clearly revealed that the ceria-modified mesoporous titania is of much interest as potential support for gold-based catalyst. The Au/ceria-modified mesoporous titania catalytic system is found to be efficient catalyst for WGSR.     

DIAGNOSTICS OF SLIP EFFECTS IN NON-NEWTONIAN MEDIA VIA ELECTROCHEMICALLY DRIVEN TRANSIENT CONVECTIVE DIFFUSION

True velocity profiles in the close vicinity of a wall can be determined by measuring the transient limiting diffusion currents after applying a step change of electrode overpotential. Slip effects in a bento-nite slurry under viscometric flow conditions were investigated by using this novel experimental technique. Electrochemically determined apparent slip velocities were found to be in excellent agreement with the results of conventional viscometric experiments.     

Vibration influence on morphological instability of a solidification front

The paper deals with the vibration influence on the stability of a planar solidification front moving with constant average velocity. The case of high frequency vibrations with small amplitude is studied. The density dependence on the solute concentration is accounted for in the framework of the Boussinesq approach. The equations for average velocity and concentration fields are obtained by multiple scale and averaging methods. A number of limit cases are studied analytically, by perturbation methods. For finite values of governing parameters the threshold of morphological instability is determined numerically. It is found that the vibrations normal to the solidification front exert destabilizing effect whereas tangential vibrations suppress the development of morphological instability.     

Synthesis of magnetic FeWO<Subscript>4</Subscript> nanoparticles and their decoration of WS<Subscript>2</Subscript> nanotubes surface

Owing to their unique properties such as mechanical, optical, magnetic, nanomaterials attracted a great interest over the last two decades. Inorganic nanotubes, e.g. WS₂, make an important class of nanomaterials with numerous potential applications. In the current work, a new synthetic strategy is developed to decorate the surface of WS₂ nanotubes with FeWO₄ nanoparticles. The FeWO₄ nanoparticles were produced by first depositing amorphous iron oxide film onto the WS₂ nanotubes’ surface and, subsequently, high-temperature annealing (600 °C). Careful analysis by electron microscopy; X-ray diffraction and other techniques were carried out. Based on these analyses, the growth mechanism of the hybrid nanostructures was elucidated. Magnetic measurements were employed to shed light on the magnetic behavior of the hybrid nanostructures. The orientation and position of the WS₂ nanotubes decorated with the FeWO₄ nanoparticles could be partially affected by applying a magnetic field using non-viscous solvents, like ethanol.     

Mesoporous and nanostructured CeO2 as supports of nano-sized gold catalysts for low-temperature water-gas shift reaction

Mesoporous particles and 1D nanorods of cerium oxides have been prepared by modifying the hydrothermal route of a surfactant-assisted controllable synthesis. Mesoporous cerias were obtained in a sealed glass vessel under continuous stirring, while ceria nanorods were obtained in a Teflon-lined autoclave without stirring. The mesoporous cerias did not show long-range mesoscopic organization, exhibiting a broad mesopore size distribution in the region 8–15 nm. A BET surface area of 100 m²/g with a total pore volume of 0.33 cm³/g is obtained for as-synthesized mesoporous ceria. The ceria nanorods exhibit a cubic crystalline structure after calcination, having the lengths in the range of 150–300 nm and diameters in the range of 10–25 nm. The growth direction of ceria nanorods is along [1 1 0]. A surface area of above 50 m²/g is obtained in the calcined nanorods. These synthesized ceria materials were used as supports of nano-sized gold catalysts, prepared by deposition–precipitation method. Their catalytic activity was evaluated by the low-temperature water-gas shift reaction. The gold/mesoporous ceria catalytic system exhibited higher catalytic activity than gold/ceria nanorods. It is revealed that the mesoporous and nanostructured cerias are of much interest as potential supports for gold-based catalysts that are effective for low-temperature water-gas shift reaction.     

Mathematical modeling of nanodispersed hardening of FCC materials

The plastic deformation of the pipe made of Cu-based alloy hardened by incoherent nanoparticles and subjected to the uniform internal pressure was investigated. The limits of elastic and plastic resistance are determined. The insignificant excess in the limit of the elastic resistance enables the plastic deformation in the most part of the pipe wall. The densities of shear-forming dislocations and prismatic dislocation loops are higher in alloys strengthened with coarse particles than in alloys strengthened with fine particles. At small distances between the strengthening particles, this effect is the most pronounced.