Long-term (1956-1999) dynamics of phosphorus in a shallow, subtropical Chinese lake with the possible effects of cyanobacterial blooms

This paper describes the long-term dynamics of phosphorus concentrations in both the lake water and the sediment in a subtropical Chinese lake, Lake Donghu. The total phosphorus (TP) concentration in the lake water experienced an upward trend from the 1950s, and peaked in 1983/1984, but declined obviously afterwards. From the 1950s to the 1990s, TP content in the upper 10 cm sediment of the lake increased steadily from 0.307 to 1.68 mg Pg DW-1 at Station I and from 0.151 to 0.89 mg Pg DW-1 at Station II, respectively. The TP increase in the lake water before mid-1980s was mainly attributed to the massive input of sewage P. The outbreak of cyanobacterial blooms coincided with the peaks of TP and Orthophosphate (PO4-P) in the water in mid-1980s, and the maximum TP of the water reached as high as 1.349 mg/1 at Station I and 0.757 mg/l at Station II (in 1984), respectively. The declines of TP and PO4-P in the water after mid-1980s was coincident with the disappearance of cyanobacterial bloom. (C) 2001 Elsevier Science Ltd. All rights reserved.

Difference in Enzyme Activity and Conformation of Glucose Oxidase Before and After Purification

EEnzyme activity of commercial glucose oxidase was enhanced after purification through a strong anionic exchange resin. In order to get a better insight into this phenomenon, surface pressure–area ( –A) isotherms and surface pressure–time ( –t) isotherms was used to study the interaction and the absorption at different pH values of the subphases between octadecylamine and glucose oxidase purified by a styrene system quaternary ammonium type strongly basic anionic exchange resin. Circular dichroism (CD), electrophoresis and enzyme activity measurements were conducted to study these phenomena. A preliminary hypothesis has been suggested to explain why the enzyme activity of purified glucose oxidase was higher than that of the commercial one. © 2002 Elsevier Science B.V. All rights reserved.

Dislocations And Twins In Nanocrystalline Ni After Severe Plastic Deformation: The Effects Of Grain Size

Deformation microstructures have been investigated in nanocrystalline (nc) Ni with grain sizes in the 50-100 nm range. It was found that deformation twinning started to occur in grains of similar to 90 nm, and its propensity increased with decreasing grain size. In most of the nc grains dislocations were observed as well, in the form of individual dislocations and dipoles. It is concluded that dislocation-mediated plasticity dominates for grain sizes in the upper half, i.e. 50-100 nm, of the nanocrystalline regime. (C) 2007 Published by Elsevier B.V.

Dislocations and twins in nanocrystalline Ni after severe plastic deformation: the effects of grain size

Deformation microstructures have been investigated in nanocrystalline (nc) Ni with grain sizes in the 50-100 nm range. It was found that deformation twinning started to occur in grains of similar to 90 nm, and its propensity increased with decreasing grain size. In most of the nc grains dislocations were observed as well, in the form of individual dislocations and dipoles. It is concluded that dislocation-mediated plasticity dominates for grain sizes in the upper half, i.e. 50-100 nm, of the nanocrystalline regime. (C) 2007 Published by Elsevier B.V.

Morphological characteristics of amorphous Ge2Sb2Te5 films after a single femtosecond laser pulse irradiation

The morphology of materials resulting from laser irradiation of the single-layer and the multilayer amorphous Ge2Sb2Te5 films using 120 fs pulses at 800 nm was observed using scanning electron microscopy and atomic force microscopy. For the single-layer film, the center of the irradiated spot is depression and the border is protrusion, however, for the multilayer film, the center morphology changes from a depression to a protrusion as the increase of the energy. The crystallization threshold fluence of the single-layer and the multilayer film is 22 and 23 mJ/cm(2), respectively. (c) 2005 Elsevier B.V. All rights reserved.

Comparison of ZnO films grown on before- and after-vapor transport equilibration (VTE) LiAlO2 substrates by pulsed laser deposition (PLD)

About Phi 45 mm LiAlO2 single crystal was grown by Czochralski (Cz) technique. However, the full-width at half-maximum (FWHM) value was high to 116.9 arcsec. After three vapor transport equilibration (VTE) processes, we can obtain high-quality LiAlO2 slice with the FWHM value of 44.2 arcsec. ZnO films were fabricated on as-grown slices and after-VTE ones by pulsed laser deposition (PLD). It was found that ZnO films on the two slices have similar crystallinity, optical transmittance and optical band gap at room temperature. These results not only show that LAO substrate is suitable for ZnO growth, but also prove that the crystal quality of LAO substrate slightly affects the structural and optical properties of ZnO film.