A new form of the high-temperature isopiestic technique has been developed for measuring isothermal–isobaric compositions of different melts with only one common volatile component; this has been applied to mercury–bismuth, mercury–cadmium, mercury–gallium, mercury–indium and mercury–tin binary amalgams at 600 K. The activities of mercury in mercury–bismuth, mercury–gallium, mercury–indium and mercury–tin amalgams have been calculated from the measured isothermal–isobaric data, taking the mercury–cadmium amalgam as a reference system. Using the results the activities of bismuth, gallium, indium and tin in the amalgams have been calculated analytically.
The activities of mercury in the Hg-Pb binary amalgam were measured at 600 K using a high-temperature isopiestic method.The activities of lead in the amalgam were calculated us- ing Gibbs-Duhem integration.
Thermodynamic studies were carried out for the vapor complex of sodium chloride with hafnium tetrachloride at 712-778 K and 0.5-3.1 kPa by using high temperature phase equilibrium-quenching experiments, with closed Pyrex glass ampoules as the reaction containers. The results show that the sole predominant vapor complex is Na2HfCl6 for the HfCl4-NaCl system under the experimental conditions. The thermodynamic equilibrium constants and other thermodynamic functions of the reaction 2NaCl(s)+HfCl4(g)=Na2HfCl6(g) have been derived from the measurements. The results for the changes in enthalpy and entropy are -65.51.5 kJ/mol and 99.62.0 J/(mol K) in the temperature range.
Excessive fertilization is often applied to produce rice. To reduce nitrogen loss and improve nitrogen use efficiency (NUE), we studied the effects of application depth (surface application, 5 and 10 cm) and shape of nitrogen fertilizers (row application and deep application of large granular fertilizer) on rice growth, soil N distribution and ammonia volatilization. The results showed that grain yield, shoot biomass and total dry biomass of the treatment with N in large granular fertilizer applied at 10 cm depth were significantly higher than those of all other treatments. Moreover, compared with the surface application, the N recovery efficiency and the N agronomic efficiency of deep application treatments were enhanced by 18.1–52.3% and 35.6–95.6%, respectively. Deep application significantly increased NH4+-N concentration at their fertilization points. During the growth season, N in large granular fertilizer treatments (mixed with clay to form an unusually large pellet of 1.0–1.5 cm in diameter) distributed closer to the roots, while N in other treatments, including row application treatments, was more widely distributed. Compared with the surface application, deep application significantly reduced NH3 volatilization and NH4+-N concentration in surface water by 58.7–64.8% and 26.0–72.5%, respectively. Furthermore, the NH3 volatilization from large granular treatment was 7.6–11.0% lower than that in the row application. In conclusion, applying N in large granular fertilizer at 10 cm depth reduces ammonia volatilization, and improves rice growth and grain yield, indicating improved NUE and lowered environmental risks.
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