A Three-Dimensional Ray Tracing Study on Whistler-Mode Chorus During Geomagnetic Activities

A three-dimensional ray tracing study of a whistler-mode chorus is conducted for different geomagnetic activities by using a global core plasma density model. For the upperband chorus, the initial azimuthal wave angle affects slightly the projection of ray trajectories onto the plane （Z, √（x^2 ＋ y^2））, but controls the longitudinal propagation. The trajectory of the upper-band chorus is strongly associated with the plasmapause and the magnetic local time （MLT） of chorus source region. For the high geomagnetic activity, the chorus trajectory moves inward together with the plasmapause. In the bulge region, the plasmapause extends outward, while the chorus trajectory moves outward together with the plasmapause. For moderately or high geomagnetic activity, the lower-band chorus suffers low hybrid resonance （LHR） reflection before it reaches the plasmapause, leading to a weak correlation with the geomagnetic activity and magnetic local time of the chorus source region. For low geomagnetic activity, the lower-band chorus may be reflected firstly at the plasmapause instead of suffering LHR reflection, exhibiting a propagation characteristic similar to that of the upper-band chorus. The results provide a new insight into the propagation characteristics of the chorus for different geomagnetic activities and contribute to further understanding of the acceleration of energetic electron by a chorus wave.

The Double Projecting Neuron of the Cat Spinal Dorsal Horn——A Study with Double Retrograde Fluorescent Tracing Technique

The new double projecting neurons were found in the cat spinal dorsal horn by the double retrograde fluorescent tracing technique.Fast Blue(FB)was injected into unilateral dorsal column nucleus(DCN)of adult cats anesthetized with pentobarbital.Nuclear Yellow(NY)was injected ipsilaterally into the lateral cervical nucleus(LCN)8-9 days later.After an additional 18-30 hrs.

STUDY ON ENRICHMENT AND SEPARATION OF TRACE ELEMENTS WITH SILICA GELS MODIFIED BY HETEROCYCLIC AZO DYES

Two types of modified silica gels were prepared by adsorption method and bonding method respectively. Enrichment and separation of trace metal ions have been done by using the column packed with modified silica gels.

Study on the determination of trace rhenium(Ⅶ)by the adsorption differential pulse polarography

The determination of trace rhenium(Ⅶ)by differential pulse polarography in the system of H_2SO_4-(NH_2OH)_2·H_2SO_4-TeO_4^(2-) is markedly improved by the addition of Nitron,which is adsorbed on the surface of mercury electrode.The limit of detection is down to 2×10^(-10) M.The adsorptive peak potential is -0.80V(vs.SCE).In the ranges of 5×10^(-10)-10^(-8),1×10^(-8)-10^(-7) and 1× 10^(-7)-10^(-6)M,there are good linear relationships between the peak current increment and the concentration,of which the relative standard deviations are 9.5,6.6,1.8% respectively with the correlation coefficients of linear regression of 0.995—0.999.The results relating to this polarographic wave show that it is an adsorption-catalytic wave.The mechanism of the electrode reaction is dis- cussed.

The potential leaching and mobilization of trace elements from FGD-gypsum of a coal-fired power plant under water re-circulation conditions

Experimental and geochemical modelling studies were carried out to identify mineral and solid phases containing major, minor, and trace elements and the mechanism of the retention of these elements in Flue Gas Desulphurisation（FGD）-gypsum samples from a coal-fired power plant under filtered water recirculation to the scrubber and forced oxidation conditions. The role of the p H and related environmental factors on the mobility of Li, Ni, Zn, As, Se, Mo, and U from FGD-gypsums for a comprehensive assessment of element leaching behaviour were also carried out. Results show that the extraction rate of the studied elements generally increases with decreasing the p H value of the FGD-gypsum leachates. The increase of the mobility of elements such as U, Se, and As in the FGD-gypsum entails the modification of their aqueous speciation in the leachates; UO2SO4, H2 Se, and HAs O2 are the aqueous complexes with the highest activities under acidic conditions.The speciation of Zn, Li, and Ni is not affected in spite of p H changes; these elements occur as free cations and associated to SO4 ^2 in the FGD-gypsum leachates. The mobility of Cu and Mo decreases by decreasing the p H of the FGD-gypsum leachates, which might be associated to the precipitation of Cu Se2 and Mo Se2, respectively. Time-of-Flight mass spectrometry of the solid phase combined with geochemical modelling of the aqueous phase has proved useful in understanding the mobility and geochemical behaviour of elements and their partitioning into FGD-gypsum samples.