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Environmental nanoparticles exist in the hydrosphere, pedosphere, biosphere, and atmosphere. Their biogeochemical and ecological impacts are some of the fastest growing areas of research today. However, efficient separation of environmental nanoparticles remains difficult. The objective of this study was to develop an automated ultrafiltration device (AUD) for efficient collection of environmental nanoparticles. The AUD utilizes an automated hydraulic ram to facilitate collection of nanoparticles using the ultrafiltration membrane with pore size in the range of 1 to 100 nm. Zeolite A was used as a model nanoparticle sample to demonstrate the efficiency of the AUD. The size distribution and mean particle sizes determined by zeta-sizer analysis on the collected nanoparticles and their transmission electron micrographs indicated the adequacy of the AUD developed in this study in collecting nanoparticles (1-100 nm). Because of its ability to reduce the time needed for sample collection, coupled with the quantity of nanoparticles collected, the AUD was far more efficient than the conventional syringe method for collecting nanoparticles. The AUD has the characteristics of automation, easy operation, and high efficiency in the separation ofnanopartides and would, thus, facilitate future research and developments in environmental nanoscience and nanotechnology and their impacts on the ecosystem. Abbreviations: AUD, automated ultrafiltration device; DDW, double deionized water; TEM, transmission electron microscope. doi: 10.2136/sssaj2008.0376

The chemical and physical properties, clay mineralogy, and [sup.14]C radiocarbon age of iron nodules found in a Ultisol located on a low elevation terrace of Taiwan were investigated. The results indicated that the amount and size of iron nodules increase with soil depth. Free iron contents in nodules were markedly higher than in the surrounding soil matrix. [Fe.sub.o]/[Fe.sub.d] ratio was low in all iron nodules, indicating that the predominant form of free iron was crystalline. Al-substituted goethite was found as the predominant oxide mineral and Al substitution ranged from 16 to 24% mole. Illite and hydroxy-interlayered vermiculite and kaolinite were the dominant clay minerals in the iron nodules. X-ray fluorescence (XRF) analysis of the iron nodules are composed primarily of Fe, Si, and Al, and minor amounts of Mn. Based on the similarity of clay mineralogical compositions and radiocarbon dating ages, it is suggested that the major driving force promoting the formation of iron nodules was in situ weathering of saprolite by the frequent wetting/drying cycles. We speculate that illuviated iron played only a minor role in their formation. Additional keywords: clay mineralogy, [sup.14]C radiocarbon, goethite, iron nodules, saprolites, soil matrix., Introduction Nodules typically occur in hydromorphic soils of humid temperate climates. Compared with concretions, nodules do not occur commonly in soils. Sherman and Kanehiro (1954) and Folster (1968) reported that [...]

Magnetostrictive TbxHo0:8−xPr0:2Fe1:8Mn0:1 (0 ⩽ x ⩽ 0.20) alloys are prepared by arc-melting and subsequent annealing. The dopant of Pr/Mn introduced into RFe2 compounds effectively stabilizes the forming of single C15 Laves phase at ambient pressure. The easy magnetization direction (EMD) varies when Tb content increases, which is accompanied by a crystalstructural transition. EMD lies along ‹1 0 0› axis for x ⩽ 0.05, rotating to ‹1 1 1› axis for x ⩽ 0.12, with a tetragonal symmetry changing to a rhombohedral one. Magnetocrystalline-anisotropy compensation is obtained with the optimized composition of x = 0.12, shifting to the Tb-poor side in comparison to Pr/Mn-free counterpart. An enhanced effect on magnetoelastic properties is achieved in Tb0:12Ho0:68Pr0:2Fe1:8Mn0:1, which simultaneously possesses a low anisotropy and high magnetostriction performance, i.e. λs ~ 420 ppm, λ111 ~ 970 ppm, and a large low-field λa ~ 390 ppm/2 kOe, being 30 % higher than that of Pr/Mn-free compound. Combining low-cost light rare earth Pr with the lower Tb content, Tb0:12Ho0:68Pr0:2Fe1:8Mn0:1 may make it promising solution in magnetostrictive applications. [ABSTRACT FROM AUTHOR]