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Basic oxygen furnace off gas (BOF OG) sludge is one important type of metallurgical residues in steelmaking industry. The presence of zinc element is one key factor that constrains the practical use of such metallurgical residues. Information about the chemical association of zinc in BOF OG sludge is fundamental for understanding its behavior during the formation and further treatments. In this paper, the spatial distribution and the chemical forms of zinc in accumulated particles of BOF OG sludge have been investigated using synchrotron radiation induced -X-ray fluorescence and -X-ray absorption near edge spectroscopy microspectroscopy. Results of -X-ray fluorescence analysis showed that zinc distributed in two ways. One was shared with iron, and its distribution showed a positive correlation with that of iron. The other was accumulated in some well-defined hot spots with high amount and its distribution showed negative correlation with that of iron. And results of -X-ray absorption near edge spectroscopy microspectroscopy indicated that ZnFe2O4 was the main constituent in some well-defined hot spots, whereas in other cases, zinc was mainly in the form of zinc carbonate. Copyright (c) 2013 John Wiley & Sons, Ltd.

This current study examined the fate of antimony (Sb) in the soil environment and its association with soil humic acid (HA). It is anticipated that a significant proportion of Sb is retained in soil organic layer; therefore, the oxidation state of Sb is controlled by the soil HA to some extent which influences Sb solubility and ecotoxicity. Parent HA material as well as prepared HA–Sb (III) composites was investigated by determining elemental composition and by performing nuclear magnetic resonance (NMR) and X-ray absorption fine structure (XAFS) spectroscopy study in order to study Sb coordination to natural macro organic ligand. The Sb (III) binding to soil derived HA mainly contributed to its open chains through carboxyl and hydroxyl moieties as revealed by the 1H and solid state 13C NMR spectroscopy. The protons in carboxylic and hydroxylic groups (those proton signals are characteristic of HAs with different origins) disappeared in the HA–Sb composite; and relative changes were observed in aliphatic proton distribution between the HA samples with and without Sb. The overall patterns of 13C NMR spectra for the investigated samples were analogous to each other; moreover, it was estimated that the cyclic structure of the HA nucleus remained unchanged during Sb (III) association. Based on the absorption edge energy and coordination numbers, Sb oxidation state in a native soil was interpreted as pentavalent, meanwhile the HA–Sb composite contained both Sb (III) and Sb (V). It was shown that HA catalyzes Sb (III) oxidation to Sb (V) but the process was relatively slow. However, XAFS spectra sensitivity was limited when studying the HA–Sb composite that was prepared from the isolated soil HA fraction, so only data on the first shell Sb–O coordination were interpreted.

A novel fluorescent single nucleotide polymorphism (SNP) assay was developed by using Graphene Oxide (GO), which provides a fast, sensitive and simple method for SNP detection. The strategy was based on the single base extension reaction and different absorption capacity of fluorescein labeled dGTP (dGTP-Fl) and double-stranded DNA (dsDNA) to GO. dGTP-Fl is incorporated into the probe by extension reaction for the mutant target but not for the wild target, which leads to recovered fluorescence for the mutant target because of weak interaction between dsDNA and GO and weak fluorescence for the wild target because of the quenched fluorescence of dGTP-Fl by GO. The method shows a linear range for the mutant-type target from 3 nM to 50 nM and 3 nM is the detection limit. It was noted that as low as 10% mutant-type target could be detected in the presence of the wild-type target, in which the concentration is 9 times higher than that of the mutant-type target.

We herein report a power-free microfluidic chip for fluorescent DNA detection with high single-nucleotide polymorphism discrimination, using a DNA intercalator and graphene oxide.

We report a label-free fluorescence turn-on approach for the sensitive and selective sensing of silver ion Ag(+) based on Ag(+) induced conformational change of cytosine-rich single-stranded DNA. A silver specific oligonucleotide (SSO) undergoes a structural transition from single-stranded DNA (ssDNA) to a C-Ag(+)-C mediated hairpin structure, which can be recognized by a double-stranded DNA (dsDNA) intercalator Sybr Green I (SG). The linear response range for Ag(+) detection was from 1 nM to 100 nM. The method presented here is highly sensitive and a limit of detection of 1 nM was obtained. More importantly, this optical method was successfully used to identify complex sample mixtures.

In this report, we developed a universal assay method for both genomic DNA and proteins by using enzyme-based multi-component optical nanoprobes. The nanoprobes are gold nanoparticles assembled with bio-recognizing and signaling elements. We firstly demonstrated that the nanoprobes could detect unpurified asymmetric polymerase chain reaction (PCR) product from genomic DNA of Escherichia coil, with the sensitivity approximately 10 times higher than that of quantitative real-time PCR assay. The limit of detection CLOD) of our nanoprobe-based method is less than 10 pg template DNA (target DNA). Using DNA aptamers as recognition elements, we also showed that as few as 0.1 nM thrombin could be colorimetrically detected with high specificity. These results indicated that the enzyme-based multicomponent nanoprobes have the capability to work with real biological samples, and have the potential in various biological and clinical applications. (C) 2011 Elsevier B.V. All rights reserved.

Co K-edge XAFS measurements were carried out to characterize the oxidation state and chemical environment of cobalt element in the blue decorations of blue-and-white porcelains manufactured by Jingdezhen official kiln during Yuan and Ming dynasties with the aim to investigate its coloring mechanism. XANES spectra showed that cobalt was present as both divalent and trivalent ions and the ratios of Co2+/Co3+ were almost similar for all samples with different historical periods. EXAFS analysis indicated that cobalt atom was situated in both octahedral and tetrahedral sites. Considering the empirical optical absorption in visible region, it was assumed that divalent ions located at tetrahedral sites made the main contribution to the blue color.

We investigate interactions between graphene oxide and a Pb(2+)-dependent DNAzyme, based on which a Pb(2+) sensor with high sensitivity, selectivity and tunable dynamic range is developed.