Influence of Laser Wavelength on Laser-induced Breakdown Spectroscopy Applied to Semi-Quantitative Analysis of Trace-Elements in a Plant Sample

Laser-induced breakdown spectroscopy (LIBS) as a powerful analytical technique is applied to analyze trace-elements in fresh plant samples. We investigate the LIBS spectra of fresh holly leaves and observe more than 430 lines emitted from 25 elements and molecules in the region 230-438 nm. The influence of laser wavelength on LIBS applied to semi-quantitative analysis of trace-element contents in plant samples is studied. The results show that the UV laser has lower relative standard deviations and better repeatability for semi-quantitative analysis of trace-element contents in plant samples. This work may be helpful for improving the quantitative analysis power of LIBS applied to plant samples.

Reduction of NO by CH4 with microwave heating

The reduction of NO by CH4 in the presence of excess O-2 over Co/HZSM-5, Ni/HZSM-5 and Mn/HZSM-5 catalysts with microwave heating was studied. By comparing the activities of the catalysts in the microwave heating mode with that in the conventional reaction mode, it was demonstrated that microwave heating could greatly reduce the reaction temperature, and could clearly expand the temperature window of the catalysts. Especially for the Co/HZSM-5 catalyst, the maximum conversion of NO to N-2 in the conventional reaction mode was consistent with that in the microwave heating mode. However, the temperature window for the maximum conversion in the microwave heating mode was from 260 to 360degreesC instead of a temperature of 420degreesC in the conventional reaction mode. The results suggest that microwave heating has a novel effect in the reduction of NO.

Direct decomposition of NO by microwave heating over Fe/NaZSM-5

Catalytic decomposition of NO was studied over Fe/NaZSM-5 catalyst. Novel results were observed with the microwave heating mode. The conversion of NO to N-2 increased remarkably with the increasing of Fe loading. The effects of a series of reaction parameters, including reaction temperature, O-2 concentration, NO concentration, gas flow rate and H2O addition, on the productivity of N-2 have been investigated. It is shown that the catalyst exhibited good endurance to excess O-2 in the microwave heating mode. Under all reaction conditions, NO converted predominantly to N-2. The highest conversion of NO to N-2 was up to 70%. (C) 2002 Elsevier Science B.V. All rights reserved.

Essential elements of integrated coastal zone management

The coastal zone comprises a narrow strip of coastal lowlands and a vast area of coastal waters. While the coastal zone represents approximately 10% of the earth's surface, its coastal lowlands are inhabited by more than 50% of the world population. The coastal zone has become the major site for extensive and diverse economic activities. Many of the coastal developing countries depend heavily on the scarce coastal resources for their economic growth.

Effects of soil type on leaching and runoff transport of rare earth elements and phosphorous in laboratory experiments

Through leaching experiments and simulated rainfall experiments, characteristics of vertical leaching of exogenous rare earth elements (REEs) and phosphorus (P) and their losses with surface runoff during simulated rainfall in different types of soils (terra nera soil, cinnamon soil, red soil, loess soil, and purple soil) were investigated. Results of the leaching experiments showed that vertical transports of REEs and P were relatively low, with transport depths less than 6 cm. The vertical leaching rates of REEs and P in the different soils followed the order of purple soil > terra nera soil > red soil > cinnamon soil > loess soil. Results of the simulated rainfall experiments (83 mm h(-1)) revealed that more than 92% of REEs and P transported with soil particles in runoff. The loss rates of REEs and P in surface runoff in the different soil types were in the order of loess soil > terra nera soil > cinnamon soil > red soil > purple soil. The total amounts of losses of REEs and P in runoff were significantly correlated.

Interactions Between Exogenous Rare Earth Elements and Phosphorus Leaching in Packed Soil Columns

Through leaching experiments and simulated rainfall experiments, characteristics of vertical leaching of exogenous rare earth elements (REEs) and phosphorus (P) and their losses with surface runoff during simulated rainfall in different types of soils (terra nera soil, cinnamon soil, red soil, loess soil, and purple soil) were investigated. Results of the leaching experiments showed that vertical transports of REEs and P were relatively low, with transport depths less than 6 cm. The vertical leaching rates of REEs and P in the different soils followed the order of purple soil > terra nera soil > red soil > cinnamon soil > loess soil. Results of the simulated rainfall experiments (83 mm h(-1)) revealed that more than 92% of REEs and P transported with soil particles in runoff. The loss rates of REEs and P in surface runoff in the different soil types were in the order of loess soil > terra nera soil > cinnamon soil > red soil > purple soil. The total amounts of losses of REEs and P in runoff were significantly correlated.

One-Step Ionic Liquid-Assisted Electrochemical Synthesis of Ionic Liquid-Functionalized Graphene Sheet Directly from Graphite

Graphite, inexpensive and available in large quantities, unfortunately does not readily exfoliate to yield individual graphene sheets. Here a mild, one-step electrochemical approach for the preparation of ionic-liquid-functionalized graphite sheets with the assistance of an ionic liquid and water is presented. These ionic-liquid-treated graphite sheets can be exfoliated into functionalized graphene nanosheets that can not only be individuated and homogeneously distributed into polar aprotic solvents, but also need not be further deoxidized. Different types of ionic liquids and different ratios of the ionic liquid to water can influence the properties of the graphene nanosheets. Graphene nanosheet/polystyrene composites synthesized by a liquid-phase blend route exhibit a percolation threshold of 0.1 vol % for room temperature electrical conductivity, and, at only 4.19 vol %, this composite has a conductivity of 13.84 S m(-1), which is 3-15 times that of polystyrene composites filled with single-walled carbon nanotubes.

Morphological transition of dry vesicles into onion-like multilamellar micelles induced through heating at high temperature

In this Letter, we report the morphological transition of dry block copolymer vesicles into onion-like multilamellar micelles induced through heating. When the temperature is higher than the glass transition temperature of block copolymer, the vesicles can collapse, and finally form onion-like multilamellarmicelles via micro phase separation. This phenomenon is observed in both A-B and A-B-A block copolymer vesicles, indicating that the technique used in this study can be an alternative method to synthesize multilamellar micelles.

Solvent extraction study of rare earth elements from chloride medium by mixtures of sec-nonylphenoxy acetic acid with Cyanex301 or Cyanex302

The extraction of rare earth elements from chloride medium by mixtures of sec-nonylphenoxy acetic acid (CA100) with bis(2,4,4-trimethylpentyl) dithiophosphinic acid (Cyanex301) or bis(2,4,4-trimethylpentyl) monothiophosphinic acid (Cyanex302) in n-heptane has been studied. The synergistic enhancement of the extraction of lanthanum (III) by mixtures of CA100 with Cyanex301 has been investigated using the methods of slope analysis and constant mole. The extracted complex of lanthanum (III) is determined. The logarithm of the equilibrium constant is calculated as - 1.41. The formation constants and the thermodynamic functions, Delta H, Delta G, and Delta S have also been determined.

Synthesis and characterization of monodisperse spherical SiO2@RE2O3 (RE = rare earth elements) and SiO2@Gd2O3:Ln(3+) (Ln = Eu, Tb, Dy, Sm, Er, Ho) particles with core-shell structure

Spherical SiO2 particles have been coated with rare earth oxide layers by a Pechini sol-gel process, leading to the formation of core-shell structured SiO2@RE2O3 (RE = rare earth elements) and SiO2@Gd2O3:Ln(3+) (Ln = Eu, Tb, Dy, Sm, Er, Ho) particles. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), photoluminescence (PL), and cathodoluminescence spectra as well as lifetimes were used to characterize the resulting SiO2@RE2O3 (RE = rare earth elements) and SiO2@Gd2O3:Ln(3+) (Eu3+, Tb3+, Dy3+, Sm3+, Er3+, Ho3+) samples. The obtained core-shell phosphors have perfect spherical shape with narrow size distribution (average size ca. 380 nm), smooth surface and non-agglomeration. The thickness of shells could be easily controlled by changing the number of deposition cycles (40 nm for two deposition cycles).

Electrochemical catalysis and thermal stability characterization of laccase-carbon nanotubes-ionic liquid nanocomposite modified graphite electrode

The hydrophobic carbon nanotubes-ionic liquid (CNTs-IL) get forms a stable modified film on hydrophobic graphite electrode surface. Laccase immobilized on the CNTs-IL gel film modified electrode shows good thermal stability and enhanced electrochemical catalytic ability. The optimal bioactivity occurs with increasing temperature and this optimum is 20 degrees C higher in comparison to free laccase. The improvement of laccase thermal stability may be due to the microenvironment of hydrophobic CNTs-IL gel on graphite electrode surface. On the other hand, the sensitive detection of oxygen has been achieved due to the feasibility of oxygen reduction by both of laccase and nanocomposite of CNTs-IL gel. Furthermore, the laccase hybrid nanocomposite also shows the fast electrochemical response and high sensitivity to the inhibitors of halide ions with the approximate IC50 of 0.01, 4.2 and 87.5 mM for the fluoride, chloride and bromide ions, respectively. It implies the feasibility of laccase modified electrode as an inhibition biosensor to detect the modulators of laccase.