ALBERT

Description: The performance of the Stirling type pulse tube cryocooler depends strongly on the design of the inertance tube. The phase angle produced by the inertance tube is very sensitive to its diameter and length. Recent developments are reported here regarding an adjustable inertance device that can be adjusted in real time. The inertance passage is formed by the root of a concentric cylindrical threaded device. The depth of the threads installed on the outer screw varies. In this device, the outer screw can be rotated four and half turns. At the zero turn position the length of the passage is 1.74 m and the hydraulic diameter is 7 mm. By rotating the outer screw, the inner threaded rod engages with additional, larger depth threads. Therefore, at its upper limit of rotation, the inertance passage includes both the original 1.74 m length with 7mm hydraulic diameter plus an additional 1.86 m length with a 10 mm hydraulic diameter. A phase shift change of 24° has been experimentally measur...

Description: This paper mainly researched the hydrothermal synthesis of Natrolite, using amorphous silicon source from the purified attapulgite. The effects of silicon source, silicon aluminum ratio, crystallization time and crystallization temperature on the synthesis of natrolite were investigated. The results showed that the optimal synthesis condition of natrolite was: Hydrothermal activated ATP with NaOH was silicon source, silicon aluminum ratio was 10:1, crystallization time lasted to 72h and crystallization temperature was 150°C, the template was removed by calcining 8 hours at 550°C. The structural formula of obtained natrolite is Na 2 Al 2 Si 3 O 10 •2H 2 O.

Description: A high concentration of phosphate in the immediate vicinity of the phosphate fertilizer zone of soil could induce K release from K-bearing minerals to soil solution. In this study, the kinetics of K release by monoammonium phosphate (NH4H2PO4) from biotite, muscovite, and microcline were investigated. The results indicate that K release from all of these minerals was promoted by 1 M NH4H2PO4 (pH 4.0). The release of K from these minerals can be described by the zero-order rate equation. The rate coefficients of K released from the minerals (2–5 µm) in 1 M NH4H2PO4 solution ranged from 0.20 to 2.09 mg kg-1 h-1 at 25°C and from 1.22 to 9.00 mg kg-1 h-1 at 45°C, respectively. The amount of K release from the same mineral samples in 1 M NH4Cl solution (pH 4.0) at 25°C was not detectable and was too low to be determined accurately at 45°C. The dfferences in the rate of NH4H2PO4-induced K release from the different minerals were explained by the chemical composition, crystal structure, and the crystallization sequence of the minerals. The activation energies of the phosphate-induced K release from these minerals ranged from 37 to 72 kJ mol-1 and the pre-exponential factor values (Arrhenius equation) ranged from 1.2 × 106 to 7.2 × 1011 mg kg-1 h-1. The examination of the phosphate-reacted minerals shows the formation of crystalline NH4-taranakite in the muscovite and microcline systems and noncrystalline products in the biotite system. The absence of the formation of crystalline NH4-taranakite in the biotite system is attributed to the Fe perturbation. These data indicate that the major mechanism of NH4H2PO4-induced K release from the K-bearing minerals was the combined effect of phosphate and protons on the alteration of minerals. Therefore, the K-supplying rate of soils in the immediate vicinity of fertilizer zones may be enhanced through phosphate fertilization. Key words: Potassium release, kinetics and mechanisms, phosphates, potassium-bearing primary minerals

Description: When monoammonium phosphate fertilizer is applied to soils, the phosphate concentration is very high and the pH is quite low in the immediate vicinity of the fertilizer granule. In this study, the release of potassium (K) by 1 M NH4H2PO4 solution at pH 4.0 from three Chinese soils, Oxisol, Alfisol and Entisol, was investigated. The results showed that NH4H2PO4 promoted K release from these soils. The NH4H2PO4-induced K release obeyed the zero-order kinetics; the release-rate coefficients from these soils at 25 °C ranged from 72 to 170 μg K kg−1 h−1, much higher than observed (4–37 μg kg−1 h−1) in 1 M NH4Cl at pH 4.0. The combined effect of phosphate and proton on the alteration of K-bearing minerals was evidently the major mechanism of the NH4H2PO4-induced K release from the soils. The data indicated that the application of NH4H2PO4 fertilizer may enhance the rate of K supply in soils and lead to the conversion of some of N and P in the fertilizer to a slowly available form in soils because of the formation of a crystalline reaction product, ammonium taranakite. Key words: Potassium dynamics, phosphate application, ammonium taranakite