Microstructure of nanoscale zinc oxide crystallites

Nanosized ZnO particles were prepared using a simple precipitation method. First, hydrozincite was obtained by adding Na₂CO₃ aqueous solutions with different concentrations to a zinc acetate precursor, previously dissolved in ethanol. We observed that the starting concentration of the precursors and the water content used for the hydrolysis influenced the size of the hydrozincite particles. The formation of the ZnO nanoparticles began after heating the hydrozyncite to 200 °C, and even when heating to 600 °C nanosized ZnO particles of 20-50 nm were obtained without agglomeration. The morphology and crystallinity of the obtained solids were characterized using XRD, SEM and TEM.     

The gasochromic properties of sol–gel WO3 films with sputtered Pt catalyst

Gasochromic films are receiving considerable attention, stimulated by the need for switchable windows that compete with more complex electrochromic ‘smart’ windows for building applications. The latest development of WO₃ films, prepared by the sol–gel route and dip-coating deposition overlaid by a thin layer of sputtered Pt metal, are presented. Colouring/bleaching kinetics of WO₃ films and WO₃ films in which a hybrid organic/inorganic sol–gel precursor (ormosil) has been added are evaluated. Results revealed that with respect to velocity of coloration, sol–gel WO₃ gasochromic films compete with the sputtered ones. Many aspects of the colouring/bleaching behaviour of the films resemble that of sputtered Pt/WO₃ films and thus confirm the similarity in the colouring/bleaching mechanisms. IR spectroscopy revealed the presence of well-defined W=O and the breaking of W–O bonds indicating the formation of H⁺… ⁻OW- and WO_3−x species in coloured films.     

Correlation of lesion appearance and histologic findings for the nodes of a breast MR imaging interpretation model

An interpretation model for evaluating magnetic resonance (MR) images of the breast was constructed that allowed differentiation of benign from malignant palpable or mammographically visible abnormalities. Architectural features define each node of the model. Investigation was subsequently made of the histologic findings in individuals within each node and of the frequency with which each histologic finding manifested as a particular architectural feature to determine whether nodal location and specific histologic findings are mutually predictive. The strongest associations were found between fibrocystic change and smooth masses, fibroadenoma and lobulated masses with nonenhancing internal septations, invasive ductal carcinoma (with or without ductal carcinoma in situ [DCIS]) and enhancing irregular or spiculated masses, invasive tubular carcinoma or radial scar and spiculated masses, medullary or colloid carcinoma and enhancing lobulated masses, invasive lobular carcinoma and the absence of a focal mass, DCIS and ductal enhancement, and DCIS (with or without invasive ductal carcinoma) and regional enhancement. Nodal location and histologic findings proved to be mutually predictive within the model; that is, the nodal location of MR imaging features within the model can be used to predict histologic findings and vice versa.     

Magnetoelastic demagnetization of ferromagnetic bodies opened in shape

An available analytical expression for irreversible variations of the remanent magnetization in an open-shaped ferromagnetic body resulting from mechanical loading is examined experimentally. The analysis was carried out using results of studies performed for chromium steels and Fe-Co alloys subjected to various heat treatments, as well as for R-Fe alloys.Translated from Defektoskopiya, Vol. 41, No. 1, 2005, pp. 32–39.Original Russian Text Copyright © 2005 by Novikov, Bakharev, Orel.     

Preparation and characterization of zinc hydroxide carbonate and porous zinc oxide particles

A simple urea aqueous solution process at low temperature (85 °C) was employed for the preparation of zinc hydroxide carbonate from zinc nitrate. The influence of different additives on the final particle morphology was studied. Porous spherical particles in the shape of chrysanthemums with an average size of 4 μm and a surface area of 16 m²/g were obtained in the presence of poly-vinyl pyrrolidone (PVP-K30). After heat treatment ZnO particles were formed that preserved the size and shape of the hydrozincite precursor. The morphology and crystallinity of the solids obtained before and after the heat treatment were characterized by FE-SEM, XRD, FTIR, BET and TG methods.     

Imidazolium-based ionic liquid derivatives for application in electrochromic devices

Novel proton-conducting electrolytes were prepared from the sol–gel precursor 1-[3-(trimethoxy-λ⁴-silyl)propyl]imidazole with the addition of either trifluoroacetic or acetic acid. The presence of trimethoxysilyl groups enabled the solvolysis and condensation reactions of silsesquioxane species. IR spectroscopy revealed that more cube-like species formed in the electrolyte prepared from trifluoroacetic acid, while cube- and ladder-like silsesquioxanes were present in the electrolyte with acetic acid. This assignation was independently confirmed by ²⁹Si NMR analyses revealing the T³ signals of trisiloxane bonding. IR spectroscopy also pointed to the formation of hydrogen bonding in the latter electrolyte, since the frequencies of the observed bands at 1710, 1409, and 1272 cm⁻¹ approached those of acetic acid. In contrast, the IR bands at 1662, 1204, and 1130 cm⁻¹ confirmed the existence of trifluoroacetate anions in the case when the electrolyte was prepared from trifluoroacetic acid. The presence of free trifluoroacetate anions contributed to the moderately higher specific conductivity of this electrolyte (4.6×10⁻⁵ S/cm) compared to that of acetic acid (1.6×10⁻⁵ S/cm). The specific conductivity of the electrolytes could be further increased by the addition of a lithium salt. All electrolytes were employed in electrochromic devices with optically active WO₃ and various inorganic counter-electrodes (CeVO₄, V₂O₅, Ti/V-oxide). Photopic transmittance changes from 30% to 40% were achieved.     

Effects of industrial and urban pollution on the benthic macrofauna in the Bay of Muggia (industrial port of Trieste, Italy)

The benthic macrofauna of the Bay of Muggia and its evolution in time was analysed in order to assess the impact of man-made pollution in this port area. The north and NE zones are totally industrialised while the southern zone is mainly used for tourism and aquaculture. The most important anthropic impacts were stagnation and direct urban and industrial discharges, which operated until the beginning of the 1990s. Forty-four stations were sampled in 1981, 12 of which were monitored over time (1975, 1981 and 1994). From 172 taxa 11783 organisms were identified. Polychaetes were the richest group, followed by molluscs, crustaceans and echinoderms. The dominant species was Corbula gibba (39.5%) followed by Pectinaria koreni (9%). Uni- and multivariate analyses showed a declining pattern for the fauna along a gradient of environmental stress. The very high concentrations of heavy metals in the Bay's sediments, especially Pb, contrasted with the diversity and biological index values found, indicating that many species could survive these conditions. The enforcement of the Italian ecological laws regarding water pollution control benefited the local macrofauna and evidenced the resilience of the system. C. gibba constituted a good biological indicator of zones of high instability (especially sedimentary) and of intermediate levels of pollution.     

Magnetoelastic Memory of High-Chromium Steel

This paper continues the series of previous publications [1–7] dedicated to the search for materials for magnetoelastic crashers. A magnetoelastic crasher is a piece of a ferromagnetic material in the residually magnetized state. When this piece is compressed or stretched, its magnetization changes irreversibly with a definite increment, which enables one to estimate the load applied to the crasher. This process is termed the effect of magnetoelastic memory. The crasher's materials should satisfy certain conditions. In particular, the residual magnetization and the character of its change under applied load should depend as weakly as possible on the applied magnetic field, time, and variations in thermal conditions in the zone of measurements. Moreover, the material should be strong enough, resistant to corrosion, and inexpensive. Among the materials that satisfy the latter three conditions are high-chromium steels. Experiments conducted with the 30Kh13 steel [7] detected the effect of magnetoelastic memory in this material, but its magnetoelastic susceptibility is relatively low. In steels with different chromium contents, the magnetostriction, alongside its magnetoelastic susceptibility, can be higher. For our studies of this problem, we selected a steel containing 14.37% of chromium.