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Matrix interference and co-existent elemental interference are the two key factors necessary to obtain accurate analysis results for Rare earth elements (REEs) in geological samples using the traditional methods. Since Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) is widely conducted in the field of trace element analysis, accurate results of REEs are obtained under optimized conditions. This method was established using ICP-MS to determine 15 REEs and is detailed in this paper. The samples were digested in sealed containers with HCl, HNO3 and HF at high temperature. The solutions were set into a constant volume. Internal standard solutions of 103Rh, 115In and 185Re were on-line loaded into the sample solution during the measurement. The recovery rates are 95%-104% and the RSDs are less than 3.5%. REEs in 24 representative ore samples from 12 countries were analyzed and are reported in this paper. The results show that importing iron ores are LREEs enrichment type. Currently, imported fine ores are mostly combined with different iron ores from multi productive areas. This provides a technical reference for the comprehensive utilization of rare earth elements in iron ore and pollution control and also provides valuable information on the origin of the iron ore.

Most studies concerned with the interactions between plasma discharges and bacteria have mainly focused on the germicidal effects and inactivation mechanisms, with little attention given to the survivor bioeffects, such as changes in metabolism. This paper investigated the production of 1,3-propanediol (1,3-PD) from glycerol by Klebsiella pneumoniae after exposure to dielectric barrier discharge (DBD) plasma in air at atmospheric pressure. Increase in 1,3-PD production as determined from flask culture was dependent on treatment time, and the highest production was observed for cells that were treated with DBD plasma for 4 min. Changes in the specific activities of the three key enzymes (glycerol dehydrogenase, glycerol dehydratase, and oxidoreductase) involved in the conversion of glycerol to 1,3-PD were detected in the extracts of treated cells. Increase in 1,3-PD production correlated with an increase in the activity levels of all three enzymes. Batch-fermentation results showed that DBD plasma-treated cells had a 59% increase in both 1,3-PD production (23.8 g/L versus 15 g/L) and productivity (1.19 g/L x h versus 0.75 g/L x h) over untreated cells. DBD plasma, therefore, can alter the metabolic activities of K. pneumoniae, resulting in enhanced production of 1,3-PD. Index Terms--Dielectric barrier discharge (DBD) plasma, inducement, Klebsiella pneumoniae, 1,3-propanediol (1,3-PD).

The inactivation mechanism of microorganisms by plasma has been attracting much attention of researchers in recent years. Some different explanations have been postulated from physical, chemical, and biological views. In this paper, we investigate the inactivation mechanism of cells exposed to dielectric barrier discharge plasma in helium at atmospheric pressure from a biochemical view, i.e., disintegration of biomacromolecules, particularly the polysaccharide on cell wall and membrane-bound proteins. The experimental results showed that a series of complex chemical reactions happened in cell debris suspension and cell suspension, leading to a decrease in the concentration of membrane-bound proteins and an increase in the concentration of proteins released from cells. Cell debris could be effectively decomposed by plasma to amino acid, maltose, glucose, acetic acid, and so on. This might be the main reason for cell lysis and death. Index Terms--Dielectric barrier discharge (DBD), disintegration, inactivation of cells, protein.

Conical dc discharge is generated between a copper cathode with a hemispherical head (2-7 mm in diameter) and a static water anode in ambient air. The discharge is hollow and is just like an umbrella if the electrical conductivity of the water electrode is higher than 17.31/[micro]s * [cm.sup.-1]. The profile is composed of three zones with different luminosities. The effects of the discharge current, air gap length, cathode dimension, and electrical conductivity of the water electrode on the discharge are studied. Volt-ampere characteristics and images of the discharge under different experimental conditions are shown to characterize the discharge. A mechanism for stabilizing the discharge is discussed. Index Terms--Air discharge, conical, hollow, water electrode.

To reveal the inactivation mechanism of microorganism in plasmas, a baker's yeast (Saccharomyces cerevisiae) sample is exposed in dielectric barrier discharge plasma in helium at atmospheric pressure. The mitochondrial activity charactering the survival probability of the yeast cell is measured by the 3-(4, 5-dimethylthiazol-2-yl) 2, 5-diphenyl-tetrazolium bromide method. The results show that the survival probability of yeast cells sharply decreases within the exposure time of 1.0-2.5 min and almost remains constant as exposure time is longer than 2.5 min. The increase of the protein concentration in the supernatant solution of yeast suspension indicates that the intracellular proteins leak to the extracellular environment when the cells undergo plasma exposure, and gross structural damage is observed by a scanning electron microscope. The possible cause of the rupture is the electrostatic tension produced by the charges accumulated on the cell surface in the plasma. In addition, the extracellular medium whose pH is changed may also contribute to the rupture of the treated yeast cells. Index Terms--Dielectric barrier discharge (DBD), mitochondrial activity, pH, protein concentration in supernatant, scanning electron microscope (SEM), yeast.

In a multipin-to-plate electrode configuration at negative polarity, a stable and diffuse atmospheric pressure glow discharge, controlled by fast airflow, was obtained. Electrical characteristics and still photos of the discharge were obtained. A mechanism of the discharge stabilization by fast airflow is discussed. Index Terms--Corona, glow discharge, plasma, spark.

The sterilizing effect and the inactivation mechanisms of low temperature atmospheric pressure helium plasma generated by dielectric barrier discharge and atmospheric cold plasma jet generated by capillary atmospheric dielectric barrier discharge on baker's yeast were analyzed and compared. The relationship of survival number versus plasma treatment time and that of yeast pH value versus plasma treatment time using different plasmas were studied. The morphology of the yeast was observed by scanning electron microscopy. Results demonstrate that two kinds of plasma have strong sterilization effect on the yeast. At least a 7 log 10reduction in the survival number after being treated with plasma generated by dielectric barrier discharge and at least a 8 log 10reduction in the survival number after being treated with cold plasma jet generated by capillary atmospheric dielectric barrier discharge are realized. Simultaneously, pH value has remarkable change after two kinds of plasma treatment and it is more remarkably changed for atmospheric cold plasma jet generated by capillary atmospheric dielectric barrier discharge. The yeast treated with two kinds of plasma ruptures completely. It is demonstrated that the sterilizing effect of cold plasma jet generated by capillary atmospheric dielectric barrier discharge is stronger than that generated by dielectric barrier discharge. The inactivation mechanisms are concerned with the rupture of the yeast and the pH value change. [ABSTRACT FROM AUTHOR]

Atmospheric pressure glow discharge in air is the focus of non-thermal plasma study currently. But it is difficult to produce due to the transition from glow to spark. To solve this problem, a method named resistance and capacitance coupled negative feedback is used to control the instability caused by the positive feedback discharge development process of pin-to-water, electrode plasma system in static atmospheric air, and the good heat conductivity characteristics of water electrode is used to enhance the stability of discharge. It is successful to prevent the transition from glow to spark and produce a stable AC glow discharge. [ABSTRACT FROM AUTHOR]

6The Cu film deposited on Si substrates by the nonequilibrium magnetron sputtering and enhanced by RF plasma is investigated. The film is analyzed by means of Scan Electron Microsope (SEM), X-ray Diffraction(XRD) and Electron Spectroscopy (ES). The results show that the film is dense, the scale of the crystal grain is about 100-1 000 nm, the interface between the film and the substrate is dense and without hole. The film is with the structure of Cu(111). From the experiments, the best experiment parameters for deposition Cu film can be found. This technique can be applied to integrated circuit. [ABSTRACT FROM AUTHOR]

The emission spectra of OH(A2 sigma --> X2 pi, O-O), O(3p5 P --> 3s5 S2(0)) and H(a)(3P --> 2S) produced by the positive pulsed corona discharge of N2 and H2O mixture in a needle-plate reactor have been successfully recorded against a severe electromagnetic interference coming from the pulsed corona discharge at one atmosphere. The relative populations and the vibrational temperature of N2 (C, v') were determined. The emission intensity of OH(A2 sigma --> X2 pi, 0-0) is obtained through the simulation of the emission spectra of the delta v = +1 vibration transition band of N2(C3 pi(u) --> B3 pi(g)). Relative populations of OH(A2 sigma), O(3p5 P) and H(a)(3P) have been obtained by the emission intensity of OH(A2 sigma --> X2 pi, 0-0), O(3p5 P --> 3s5 S2(0)) and H(a)(3P --> 2S) and Einstein's transition probability. The effects of discharge voltage and pulse repetition rate and oxygen flow on the relative populations of OH(A2 sigma), O(3p5 P) and H(a)(3P) are investigated.