Surface-modified Phanerochaete chrysosporium as a biosorbent for Cr(VI)-contaminated wastewater

To improve the removal efficiency of heavy metals from wastewater, the surface of a fungal biomass was modified to obtain a high-capacity biosorbent for Cr(VI) in wastewater. The effects of pH, initial concentration, and sorption time on Cr(VI) removal by polyethylenimine (PEI)-modified Phanerochaete chrysosporium were investigated. The biomass adsorption capacity was significantly dependent on the pH of the solution, and the optimum pH was approximately 3.0. The maximum removal for Cr(VI) was 344.8 mg/g as determined with the Langmuir adsorption isotherm. Pseudo-first-order Lagergren model is better than pseudo-second-order Lagergren model when simulating the kinetic experiment results. Furthermore, an amount of Cr(VI) was reduced to Cr(III), indicating that some reactions occurred on the surface of the biomass leading to the reduction of Cr(VI). The point of zero potential for the modified biomass increased from an initial pH of 3.0 to a much higher value of 10.8, indicating that the PEI-modified biomass is better than the pristine biomass for adsorption of anionic adsorbates. Results showed that the PEI-modified biosorbent presented high efficiency in treating Cr(VI)-contaminated wastewater.     

Heavy metal source analysis in municipal solid waste (MSW): case study on Cu and Zn

This research contributes to the knowledge of the heavy metal sources in municipal solid waste (MSW). Samples were collected from 8 cities of Zhejiang province, Eastern China. Cu and Zn, the most two conventional heavy metals with extensive distribution in many kinds of MSW components, were investigated. It shows components of kitchen waste (KW), ash (AS), plastic (PL), and paper (PA) have high universality in MSW and accounted for 55.1-95.5% in each MSW sample. Moreover, these four components are also the main heavy metal sources of MSW, which accounted for 76.3% and 82.3% contribution of the Cu and Zn contents, respectively. The Cu and Zn contents in the gross MSW sample were 41.2-1643.7 mg kg(-1) and 109.3-1077.9 mg kg(-1), respectively, which on different degree exceed the set standard for "environmental quality standard for soil" (Cu, 100 mg kg(-1); Zn, 400 mg kg(-1)) of China and have high potential of environmental risk. The heavy metal contents in the gross MSW do not have spatial variation but present high seasonal variation, significantly higher in summer than winter (P<0.01). Much more attention should be paid on the MSW management in summer to avoid heavy metal pollution.     

Physicochemical and toxicological properties of commercial carbon blacks modified by reaction with ozone

Ozonation of two commercial carbon blacks (CBs), Printex 90 (P90) and Flammruss 101 (F101), was carried out and changes in their morphology, physical properties, and cytotoxicity were examined. The hypothesis examined was that different methods of manufacture of CBs influence their chemical reactivity and toxicological properties. Structural changes were examined by X-ray photoelectron spectroscopy, infrared spectroscopy, Raman spectroscopy, and electron paramagnetic resonance spectroscopy (EPR). Introduction of surface oxygen functionality upon ozonation led to changes in surface charge, aggregation characteristics, and free radical content of the CBs. However, these changes in surface functionality did not alter the cytotoxicity and release of inflammation markers upon exposure of the CBs to murine macrophages. Interaction of macrophages with F101 resulted in higher levels of inflammatory markers than P90, and the only structural correlation was with the higher persistent radical concentration on the F101.     

Purification, cloning, expression and immunological analysis of Scylla serrata arginine kinase, the crab allergen

BACKGROUND: Although crustaceans have been reported to be one of the most common causes of IgE‐mediated allergic reactions, there are no reports about the characterization and identification of arginine kinase (AK) from the mud crab (Scylla serrata) as allergen. In the present study, the purification, molecular cloning, expression and immunological analyses of the IgE allergen AK from the mud crab were investigated. RESULTS: The results showed that cloned DNA fragments of AK from the mud crab had open reading frames of 1021 bp, predicted to encode proteins with 356 amino acid residues. Sequence alignment revealed that mud crab AK shares high homology with other crustacean species. Mud crab AK gene was further recombined with the vector of pGEX‐4T‐3 and expressed in Escherichia coli BL 21. 2‐D electrophoresis suggested that native AK (nAK) and recombinant AK (rAK) shared the same molecular weight of 40 kDa, and the pI is 6.5 and 6.3, respectively. The nAK and rAK were further confirmed by matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry. Immunoblotting analysis and colloidal gold immunochromatographic assay (GICA) using sera from subjects with crustacean allergy confirmed that the nAK and rAK reacted positively with these sera, indicating AK is a specific allergen of mud crab. CONCLUSION: Both of purified nAK and rAK reacted positively with sera from subjects with crustacean allergy in immunoblotting and GICA analysis, indicating AK is a common allergen of mud crab. In vitro expressed AK is proposed as a source of the protein for immunological or clinical studies. Copyright © 2011 Society of Chemical Industry     

Nondestructive ion trap mass analysis at high pressure

A method for performing nondestructive ion trap mass analysis at high pressures (>1 mTorr) has been developed using image current measurement with constant dipolar excitation. Instead of monitoring the ion secular motion, a harmonic of the ion motion was used for narrow band image current measurement followed by Fourier Transform. The capability of this technique has been demonstrated with mass analysis using a single measurement at pressures of 10 mTorr or higher. Methods for mixture analysis and tandem mass spectrometry have also been developed for nondestructive mass analysis.