Preparation of La2Zr2O7 by Sol—Gel Route

The La₂Zr₂O₇ phase was prepared from metal acetylacetonates by a sol—gel route without any intermediate phase formation. X-ray peaks appeared at a temperature as low as 500°C at the positions expected for La₂Zr₂O₇, although they were broad. The crystal structure of La₂Zr₂O₇ was found to be of the fluorite type below 900°C and of thepyrochlore type above 1000°C. The substitution of a small amount of Eu for La was carried out to investigate the crystal structure from the viewpoint of fluorescence, and these results confirmed the formation of fluorite type La₂Zr₂O₇ below 900°C.     

Nafion and modified-Nafion membranes for polymer electrolyte fuel cells: An overview

Polymer electrolyte fuel cells (PEFCs) employ membrane electrolytes for proton transport during the cell reaction. The membrane forms a key component of the PEFC and its performance is controlled by several physical parameters, viz. water up-take, ion-exchange capacity, proton conductivity and humidity. The article presents an overview on Nafion membranes highlighting their merits and demerits with efforts on modified-Nafion membranes. Energy security refers to various security measures that a given nation, or the global community as a whole, must carryout to maintain an adequate energy supply     

Separation of nickel from copper in ammoniacal/ammonium carbonate solution using ACORGA M5640 by selective stripping

Separation of nickel from copper in ammoniacal/ammonium carbonate solution using ACORGA M5640 by selective stripping was carried out. The influence of equilibration time, equilibrium pH and extractant concentration on the extraction of both the metals was studied. It was found that the copper extraction equilibrium was reached in a shorter time than the nickel extraction equilibrium. Nickel extraction decreases above an equilibrium pH of 9.0, while the extraction of copper remains unaffected by the changes in the equilibrium pH range of 7–10. Co-extraction, ammonia scrubbing and the selective stripping of copper and nickel were performed for a solution containing 3 g/l each of copper and nickel and 60 g/l ammonium carbonate. The extraction and the percentage stripping of copper and nickel were almost quantitative.     

Strombus gigas inspired biomimetic ceramic composites via SHELL—Sequential Hierarchical Engineered Layer Lamination

Nature has produced remarkable structural designs based on many millennia of evolutionary optimization. Biological materials, such as the sea-shell, possess unique microstructures and properties that provide inspiration for the next generation of structural ceramics. Strombus gigas (Queen conch) shells contain a hierarchical, multilayered, crossed-lamellar architecture built with two natural materials (calcium carbonate and protein) with at least three identifiable scales (or orders) of structure. Drawing on Strombus gigas for inspiration, we have developed a new process to realize such complex micro-architectures in macroscopic form. SHELL (Sequential Hierarchical Engineered Layer Lamination) is a thermoplastic forming process that is capable of producing the third order structural complexity over the micron-millimeter length scales. We have fabricated silicon nitride—boron nitride ceramics via SHELL that are endowed with excellent damage tolerance, exhibit graceful failure, and exhibit toughening mechanisms similar to those observed in Strombus gigas.     

Mapping the total phosphorus concentration of biosolid amended surface soils using LANDSAT TM data

Conventional methods for soil sampling and analysis for soil variability in chemical characteristics are too time-consuming and expensive for multi-seasonal monitoring over large-scale areas. Hence, the objectives of this study are: 1) to determine changes in chemical concentrations of soils that are amended with treated sewage sludge; and 2) to determine if LANDSAT TM data can be used to map surface chemical characteristics of such amended soils. For this study, we selected two fields in NW Ohio, designated as F34 and F11, that had been applied with 34 and 11 ton acre^− 1 of biosolids, respectively. Soil samples from a total of 70 sampling locations across the two fields were collected one day prior to LANDSAT 5 overpass and were analyzed for several elemental concentrations. The accumulation of Ba, Cd, Cu, S and P were found to be significantly higher in the surface soils of field F34, compared to field F11. Regression equations were established to search for algorithms that could map these five elemental concentrations in the surface soils using six, dark-object-subtracted (DOS) LANDSAT TM bands and the 15 non-reciprocal spectral ratios derived from these six bands for the May 20, 2005, LANDSAT 5 TM image. Phosphorus (P) had the highest R² adjusted value (67.9%) among all five elements considered, and the resulting algorithm employed only spectral ratios. This model was successfully tested for robustness by applying it to another LANDSAT TM image obtained on June 5, 2005. Our results enabled us to conclude that LANDSAT TM imagery of bare-soil fields can be used to quantify and map the spatial variation of total phosphorous concentration in surface soils. This research has significant implications for identification and mapping of areas with high P, which is important for implementing and monitoring the best phosphorous management practices across the region.     

Removal of inorganic pollutants in rainwater by a peat-derived porous material

Although roof-top runoff water has been considered as an alternative water resource, the harvested rainwater needs to be treated for further use because it usually contains various contaminants such as heavy metals and microbes. The degree of the harvested rainwater quality depends upon its end use such as drinking water and irrigation. Especially, when harvested rainwater is to be used as gray water, a cost effective treatment system is required. Accordingly, the main purpose of this study was to examine the adsorption characteristics of peat, cost-effective biosorbent, for various inorganic pollutants such as ammonium, copper, cadmium and lead from roof-top runoff water. As part of efforts to investigate the sorption properties of peat, batch isotherm tests were carried out under various pH conditions. The characterization of peat was carried out with powder X-ray diffraction, Brunauer–Emmett–Teller, and scanning electron microscope measurements. Both heat-treated peat and non-treated peat appeared to have high sorption capacity for all inorganic contaminants (NH₄ ⁺, Cu²⁺, Cd²⁺, and Pb²⁺). An interesting finding is that the amount of NH₄ ⁺ sorbed on the sorbents was slightly higher compared to the other cations. Also, the sorption capacity of the peat sorbents increased with an increase of pH. On the other hand, kinetic data were well described by pseudo-second kinetic model, indicating that removal mechanism of cations by peat-derived sorbents is likely due to chemisorptions. The results of this study suggested that peat-derived porous materials can be used as effective sorbents for removal of cationic inorganic contaminants from harvested rainwater.     

Toughness in synthetic and biological multilayered systems

Toughness in hard biological tissues is associated with fibrous or lamellar structures that deflect or stop growing cracks. In some cases, such as nacreous shell, protein interlayers absorb much of the crack energy. In other tissues, such as tooth enamel, the toughness derives from the mineral microstructure, and the small amount of residual protein apparently has little effect. There have been a number of efforts to make tough synthetic materials using layered structures. In this work, freeform fabrication has been used to make layered structures with a view to introducing similar toughness into brittle materials. Results are presented for epoxy-glass composites with glass fabric interlayers, porous alumina back-filled with aluminium metal, and layered glass-ceramic/silver materials.