Determination of low boron concentrations in nutrient solution
To study boron (B) deficiency and toxicity in plants in flowing solution culture, it is necessary to establish a wide range of solution B concentrations. The ability of inductively coupled plasma atomic emisson spectrophotometry (ICPAES) to determine solution B concentrations ranging from 0.15 μM to 925 μM was investigated. The reliablity of B concentration determination in nutrient solutions containing <10 μM B is poor. A technique, involving sorption by a B-specific resin (Amberlite-743), was established to concentrate the B present in low B nutrient solutions and to enable reliable measurement using ICPAES following elution from the resin. Acceptable, reproducible recoveries of B from low B solutions, containing known concentrations of B, were obtained using this technique. The technique enables the imposition, monitoring and maintenance of solution B concentrations well below the direct detection limits of ICPAES and colorimetric procedures. ei]L V Kochian
Determination of boron isotope ratios in geological materials by inductively coupled plasma mass spectrometry
A method for the determination of B isotopes ratios in a variety of geological materials is described. Boron isotope ratios are determined with a precision of 0.7% in materials containing as little as 0.5 ppm B. Sample material is leached with HCl in sealed pressure tubes or fused with sodium carbonate. Separation and/or preconcentration of B from matrix elements is accomplished by using Amberlite XE-243, Dowex 50W-X8, or Chelex-100 resins. The use of NASS-1 reference sea water is suggested as a reference material for calculating and comparing isotope shifts for different geological amterails. Nonspectroscopic interferences due to the presence of concomitant elements in solution are shown to cause /sup 11/B ion count rate suppression at concentrations of Na above 2000 ppm. The presence of excess amounts of concomitant elements causes a matrix-induced mass discrimination effect. Boron isotopes ratios (/sup 11/B//sup 10/B) for the materials studied ranged from 3.91 to 4.18 for basalt and sea water samples, respectively.
Numerical Simulation of Induction Heating Process of Continuous Casting Slab
Compared with traditional blazing furnace, the Continuous Casting-Direct Rolling is an advanced manufacturing steel technology, which can reduce energy waste, decrease pollution and enhance efficiency. The characteristics of steels during induction heating are complex, the change of material properties with temperature makes exact analysis methods very difficult to implement. Therefore, a powerful computer aided numerical tool (i.e., finite difference analysis) is selected to numerically model the induction heating process in this paper. The mathematic model coupling with electromagnetic field and thermal field was established, and it was solved by finite difference method (FDM), thus the slab temperature distribution and its variation with time were obtained, and the characteristics in whole induction heating process were studied. To validate the program feasible, the results were evaluated and compared with experiment results, which showed that the simulation results are reliable and effective. The skin effect in heating process from the two results was studied and demonstrated, the temperature change caused by different parameters such as the induced power intensity and the corner radian were also presented, which indicate that the slab temperature can be heated uniformly through adjusting these parameters, thus the continuous casting slab can meet the rolling requirement.