Upgrading of iron ores using microwave assisted magnetic separation followed by dephosphorization leaching

This paper describes the development of a flowsheet using a combination of sample preparation, magnetic separation (in a range 0.4–1?T), microwave treatment (in a range 0.54–0.9?kW), and leaching operations (HCl, in a range 0.25–1.25?M) for the beneficiation of iron ores (Total Fe [T_FE]: 55.48%). The work was aimed at recovering T_FE from the non-magnetic product by increasing its magnetic susceptibility through microwave treatment. It was found that goethite mineral in the non-magnetic product at a temperature of around 200^oC was converted to paramagnetic (hematite) or ferromagnetic minerals (maghemite and magnetite) by microwave treatment and overall beneficiation recovery was improved. The phosphorus (P) content in the final product was then removed by leaching in 0.25?M HCl. The iron loss from the final concentrate during leaching was found to be 0.78%, which was negligible. Overall, a final concentrate assaying 61.78% T_FE with a recovery of 94.97%, and containing 0.04% P with 94.73% removal was obtained providing satisfactory results for use in the industry. This study gives an alternative way for possible future studies to produce an iron concentrate with a high recovery from problematic iron ores, which can be categorised due to its P content.     

Memory Partitioning in the Limit

International Journal of Parallel Programming - The key difficulties in designing memory hierarchies for future computing systems with extreme scale parallelism include (1) overcoming the design...     

Protein staining methods in quantitative cytochemistry

The chemical action and practical application of the Naphthol Yellow S, Alkaline Fast Green, Coomassie Brilliant Blue, Dinitrofluorobenzene and some lesser known protein staining methods have been surveyed with respect to their potentialities for quantitative cytochemical analyses. None of the dyes can be said to bind to any specific protein or group of proteins, but each may be used to analyse the presence of one or more particular amino acid residues. For the cytophotometric measurement of the 'total protein content' of individual cells and cell organelles the covalent binding Dinitrofluorobenzene and the electrostatic binding Naphthol Yellow S can properly be used. Fast Green FCF, applied at alkaline pH, binds electrostatically to the basic amino acid side chains of strongly basic proteins only but not in a quantitative (stoichiometrical) way. Coomassie Brilliant Blue, recently introduced to protein cytochemistry, may be useful for quantitative purposes. The combined Feulgen-Pararosaniline(SO2)/Naphthol Yellow S and Dinitrofluorobenzene/Feulgen-Pararosaniline(SO2) methods enable the simultaneous cytophotometric analysis at two different wavelengths for protein and DNA within the same microscopical preparation.     

Union leadership and member attitudes: A multi-level analysis.

Analyses of union leadership roles show that union presidents should have both a within-union focus and an external focus. The authors combined multi-level survey data from 3,871 union members in 248 local teachers' unions with archival and field staff data to examine relationships between leadership and members' perceptions of union instrumentality and justice, union commitment, and participation. The results showed significant union-level effects on members' beliefs about, and attitudes toward, their unions, attributable to the presidents' internal and external leadership, wage outcomes, and union characteristics. Relationships between internally focused leadership and members' loyalty and willingness to work for the union were partially mediated by perceptions of union instrumentality and justice. These perceptions fully mediated the relationship between externally focused leadership and union loyalty. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Allocating resources to research and development projects in a competitive environment

Firms who are involved in R&D activities are often “racing” against competitors to become the lirst to attain the desired breakthrough. The goal might indeed be to "beat" the competitors in as many such R&D races as possible. However, when resources are limited, and competitors' budget allocation to these R&D activities unknown, the challenge becomes to devise a method of allocating R&D budgets to activites in a strategically “optimal” way. We model the decision problem of a firm wishing to allocate a fixed budget among several activities, so as to maximize the expected profit from the activities it captures. The probability of capturing an activity is an increasing function of one's allocation to it, and a decreasing function of the competitor's allocation. For a specific plausible capture-probability function, we find the optimal allocation between two activities conditional on the competitor's allocation (the “reaction curve”). Nash and Stackelberg equilibria for that model are then characterized. Wc also briefly explore the implications of more general, or different, capture-probability functions.     

Application of a hybrid model of mushy zone to macrosegregation in alloy solidification

Solidification of an aqueous ammonium chloride (NH₄Cl-H₂O) solution inside a two-dimensional cavity is numerically investigated using a continuum mixture mathematical model. The mushy region where solid and liquid phases co-exist is considered a non-Newtonian fluid below a critical solid fraction, and a porous medium thereafter. This critical solid fraction is chosen as that corresponding to the coherency point, where a solid skeleton begins to form. The numerical results show that the solidification of a hypereutectic NH₄Cl-H₂O solution is mainly characterized by the rejection of solute at the mushy region and double diffusive convection induced by the opposing solutal and thermal buoyancy forces. The mathematical model agrees satisfactorily with the available experimental and numerical data.     

新疆地区密点麻蜥不同亚种体与尾中14种元素分析比较

用原子吸收分光光度计测定了新疆地区密点麻蜥不同亚种体与尾中14种元素的含量，发现其K、Ca、Mg、Fe、Zn等元素的含量都比较丰富；有毒元素Pb含量均较低：仅在叶城亚种体中含有Cd，且含量极低；密点麻蜥不含有Co、Ni，并讨论了这些元素与其药用机理的关系，为密点麻蜥的进一步开发利用提供一定的科学依据。