Effects of Soil Copper Concentration on Growth, Development and Yield Formation of Rice (Oryza sativa)

Pot experiments were conducted in 2002 and 2003 to investigate the effects of soil copper（Cu） concentration on growth, development and yield formation of rice by using the japonica cultivar Wuxiangjing 14 and hybrid rice combination Shanyou 63. The plant height, leaf number, elongated internode number and heading date of rice plants were not affected at soil Cu levels below 200 mg/kg, but affected significantly at above 400 mg/kg. The inhibitory effects on rice growth and development were increased with the increment of soil Cu levels. The grain yields decreased significantly with raising soil Cu levels. The main reasons for the grain yield reductions under lower soil Cu levels （100, 200 mg/kg） were mainly due to the decrease of number of spikelets per panicle, however, under higher soil Cu levels （more than 400 mg/kg）, both panicle number and number of spikelets per panicle contributed to the yield loss. The decreases of panicle number by Cu stress were mainly attributed to slow recovery from transplanting, delayed tillering and reduced maximum tiller numbers. The reduction of number of spikelets per panicle under soil Cu stress resulted from the decreases of both shoot dry weight （SDW） at the heading date and the ratio of spikelets to SDW. Total biomass at maturity decreased significantly with the increase of soil Cu levels, while economic coefficient showed non-significant decrease except under soil Cu levels above 800 mg/kg.

Oxygen pressure acid leaching of Gacun complex Cu concentrates

The treatment of the Gacun complex Cu concentrate with high contents of Pb,Zn,Ag,etc by oxygen pressure acid leaching was studied.It is unusual that tetrahedrite,whose treatment was rarely studied,is the primary copper mineral of the concentrates.Most of silver also occurs in the mineral.The optimum operating parameters of oxygen pressure acid leaching were established by conditional tests.Pilot scale test was carried out under the parameters,and the leaching rates of copper and zinc are as high as 97.10% and 89.83% while lead and silver are transformed into sulfate and sulfide respectively and stay in leaching residue.The copper and zinc in lixivium were reclaimed by extraction-electrowinning and purification-electrowinning,respectively,and the lead and silver in the residue were reclaimed separately by chloride leaching and thiourea leaching.The extraction rate of copper achieves 96%,and the leaching rates of lead and silver reach 90% and 95%,respectively.

Epitaxial growth of MOCVD-derived YBCO films by modulation of Cu(tmhd)_2 concentration

Metal-organic chemical vapor deposition was applied to fabricate YBa2Cu3OT-a （YBCO） films on singlecrystal LaA103 （001） substrates for its high deposition rate, easy adjustment on film composition, and low requirement on vacuum apparatus. The effects of Cu（tmhd）2 concentra- tion in the precursor on the properties of YBCO films were systematically investigated. X-ray diffraction （XRD） reveals that the mole ratio of Cu/Ba in the precursor from 0.77 to 0.97 is helpful to improve the crystallization and out-of-plane orientation of YBCO films; however, it hardly affects the inplane texture. Scanning electron microscope （SEM） shows the dense, crack-free but rough surface, on which there are Cu-O and Ba-Cu-O outgrowths identified by energy-dispersive spectrometer （EDS）. As the mole ratio of Cu/Ba increasing, the average size of Ba-Cu-O precipitates keeps increasing and the film composition becomes inhomoge- neous at the mole ratio of Cu/Ba of 0.97. The 250 nm thick YBCO film prepared at the mole ratio of Cu/Ba of 0.91 shows the critical current density （Jc） of 4.0 MA.cm-2 （77 K, 0 T）.

Revealing the influence of high magnetic field on the solute distribution during directional solidification of Al-Cu alloy

The effect of the high magnetic field(MF)on the distribution of solute concentration during directional solidification of Al-Cu alloy under low growth speed was experimentally investigated.The amount of nonequilibrium eutectic is quantified via X-ray computed tomography(XCT)and demonstrated to reduce with the application of MF.Further,experimental results reveal that the MF alleviates the microsegregation and increases the average Cu concentration in solid solution,leading to the increases of the effective partition coefficient ke.It was also found that Cu concentration in solid solution increases continuously with the increasing intensity of MF,following the strengthening of micro-hardness.The change of ke under the MF is demonstrated to attribute to the thermoelectric magnetic convection(TEMC)in the mushy zone and the thermoelectric magnetic force(TEMF)acting on the solid.The TEMC is supposed to cause secondary convection owing to the inequality in flow velocities of circulation in different positions of dendrite stem.And the vacancies created by the proliferation and movement of dislocations induced by TEMF in the matrix is supposed to be able to capture solute atoms and thus enhance the solute concentration in the solid solution.