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A silicon carbide (SiC) vertical channel junction field
effect transistor (VJFET) was fabricated based on in-house SiC epitaxial wafer
with trenched and implanted method. Its forward drain current is in excess of 3.12 A
(170 W/cm2) with a current gain of ID/IG = 19746
at gate bias VG = 3 V and drain bias VD = 5.5 V. The
SiC VJFET device’s related specific on-resistance 54 mΩ·cm2. The
BV gain is 250 V with Vg from -10 V to -4 V and is
350 V with Vg from -4 V to -2 V. Self-aligned
floating guard rings provide edge termination that blocks 3180V at a gate bias
of ?14 V and a drain-current density of 1.53 mA/cm2.
Large amounts of uranium waste rocks and
tailings resulting from the exploitation and treatment of uranium ore at the
Northern Guangdong mine (South China) have been accumulated in dams (tailing ponds).
To reduce the dispersion of natural radionuclides into the environment, some dams
were revegetated with arbor, bush and sward. Besides these plants, Miscanthus
floridulu is the dominant plant growing in some of the dams. The uptake and
distribution of naturally occurring uranium (238U), thorium (232Th), radium (226Ra)
and potassium (40K) by Miscanthus floridulu plant from different sample sites
of uranium mine were studied under native conditions. The bioconcentration
factors (BCFs) of soil to Miscanthus floridulu above-ground and root were
calculated and observed to be in the range of 0.14 to 7.74 and 2.71 to 17.83 for 238U, 0 to 3.02
and 0 to 3.29 for 232Th, 0.15 to 79.76 and 1.01 to 50.22 for 226Ra and 3.00
to 8.41 and 2.69 to 11.22 for 40K, respectively. The transfer
factors (TFs) of Miscanthus floridulu root to aboveground were also calculated
and observed to be in the range of 0.01 to 0.73 for 238U, 0 to 0.99 for 232Th,
0.08 to 1.50 for 226Ra and 0.57 to 1.94 for 40K, respectively. The results showed
that, Miscanthus floridulu is 238U and 226Ra-accumulating plant
with significant absorption and accumulation characteristics.
Thermal loss of exhaust flue gas accounts for the
largest proportion of the total boiler thermal loss. Nowadays in China, the
exhaust gas temperature in many thermal power plants is much higher than the
designed value, thus, the recycle and reuse of the waste heat of tail flue gas
is necessary. However, lower exhaust gas temperature will aggravate low temperature
corrosion of the tail heating surface, which also causes huge economic losses.
In order to solve this problem, this paper designs a monitoring experiment
platform of flue gas low temperature corrosion, which can measure the corrosion
condition of different materials by different flue gas compositions and
temperature corrosion speeds. Besides, effects of low temperature corrosion
factors are analyzed to find the best exhaust gas temperature and the surface material
of tail heating surface.
Bioavailability of nitrogen (N) and phosphorus (P) is known to affect marine phytoplankton physiology, thus influencing their primary productivity; and it’s of general interest to see how the N or/and P additions affect the differently cell-sized phytoplankton assemblages. Data from the northern South China Sea showed that P addition increased up to 6 times of total chl a content within 24 h in the estuarine water; and N+P addition increased more than 20 times of chl a within 144 h in the pelagic water. The P addition powered 18.0% and 149% increase in the carbon fixation of larger (>3 μm) and smaller (<3 μm) cell assemblies from the estuarine water, respectively; while the limited effects were observed between them in the pelagic water. Additions of N and P interactively increased the carbon fixation of both cell-sized assemblies in the pelagic water, but only small cell-sized fraction in the estuarine water. Moreover, the estuarine phytoplankton cells appeared to respond faster to the nutrient additions than the pelagic ones, and the smaller cells respond to a greater extent than their larger counterparts in the estuarine water but not in the pelagic water.