nanocrystalline particles of cerium oxide (ceo2) have been prepared by the chemical precipitation method using cerium nitrate and urea with a molar ratio of 1:2. the results revealed that the formation of ceo2 fine particles is influenced by molar ratio of metal nitrates to fuel. well faceted ceo2 nanoparticles, were synthesized by thermal-assisted dissociation method at reflux temperature in a...

We used cosmogenic nuclide and geochemical mass balance methods to measure long-term rates of chemical weathering and total denudation in granitic landscapes in diverse climatic regimes. Our 42 study sites encompass widely varying climatic and erosional regimes, with mean annual temperatures ranging from 2 to 25 jC, average precipitation ranging from 22 to 420 cm year , and denudation rates ran...

We present the new scavenging scheme SCAV, simulating the removal of trace gases and aerosol particles by clouds and precipitation in global atmospheric chemistry models. The scheme is quite flexible and can be used for various purposes, e.g. long term chemistry simulations as well as detailed cloud and precipitation chemistry calculations. The presence of clouds can substantially change the ch...

Background: Mature landfill leachate is a complicated mixture which is resistant to biological treatment processes. The treatment of mature landfill leachate by struvite precipitation and Fenton oxidation was the main objective of the current research. Methods: Struvite with the phosphate/ammonia/magnesium molar ratio of 1/1/1.05 was considered during all experiments. Five initial pHs of 3, 4,...

High-elevation regions in the United States lack detailed atmospheric wet-deposition data. The National Atmospheric Deposition Program/National Trends Network (NADP/NTN) measures and reports precipitation amounts and chemical constituent concentration and deposition data for the United States on annual isopleth maps using inverse distance weighted (IDW) interpolation methods. This interpolation...

A kinetic Ising model description of Liesegang phenomena is studied using Monte Carlo simulations. The model takes into account thermal fluctuations, contains noise in the chemical reactions, and its control parameters are experimentally accessible. We find that noisy, irregular precipitation takes place in dimension d52 while, depending on the values of the control parameters, either irregular...

Sulfur compounds have been considered as potential thermoelectricmaterials due to recently reported high ZT values. However, the synthetic methods for these compounds are too expensive or complicated to be applied to large-scale production. Among these compounds, tin sulfide (SnS) has attracted increasing attention not only because of its extremely low thermal conductivity (below 1.0 W (m K) ) ...

We report novel results on self-organized three-dimensional spiral and target patterns exhibiting anomalous superdiffusive behaviour in a reaction-diffusion system with simultaneous precipitation and polymorphic transformation of mercuric iodide without external forcing. The superdiffusive dynamics of propagation of the targets/spirals and their breakup are presented.

Chemical precipitation is a useful technology to remove ammonium (NH(4)(+)) from landfill leachate. In this paper, the removal of ammonium from landfill leachate was studied. The objective of this study was to investigate optimum pH, optimum molar ratio, and different kinds of chemicals combinations for magnesium ammonium phosphate (MAP) precipitation. Furthermore, the kinetics of MAP formation...

In this study, wet-chemical process was performed to prepare nano-size hydroxyapatite (HA) powders (≈10 nm) by varying concentration (low, medium and high) of the starting solutions in order to increase the amount of as-dried HA powders with different process conditions. Particle sizes and density were analyzed and differential thermal analysis was used to determine the glass transition (Tg) an...