CaO-MgO-P_2O_5-SiO_2-CaF_2系统自硬性玻璃的研究

为研究钙离子、镁离子在体内环境中对自硬性玻璃结晶行为的影响,为自硬性生物活性玻璃的临床应用提供依据,本文设计了CaO-P2O5-SiO2-CaF2(Ca-glass)和CaO-MgO-P2O5-SiO2-CaF2(CaMg-glass)系统玻璃并使用模拟体液(simulated body flu id,SBF)进行了研究。首先采用磷酸氢二氨[(NH4)2HPO4]/[NH4H2PO4]硬化液与Ca-glass、CaMg-glass制成硬化体,然后使用X射线衍射(XRD)、扫描电镜(SEM)、失重、力学分析等方法,研究硬化体在SBF中的结晶性、降解性和力学性能。实验结果表明,玻璃粉末与磷酸铵缓冲溶液反应形成了磷酸铵钙[(NH4)2.Ca(HPO4)2.H2O]硬化体。硬化体经过SBF浸泡,Ca-glass系统硬化体中部分磷酸铵钙转化成羟基磷灰石,而CaMg-glass系统硬化体仍然为磷酸铵钙。Ca-glass与CaMg-glass硬化体在SBF中浸泡28天分别降解19.4%和31.3%,抗压强度分别为93.14MPa和64.52MPa。镁离子的歧化作用是导致Ca-glass、CaMg-glass硬化体结晶性能、降解性能以及力学性能差别的主要原因。

Effects of Urea Ammonium Chloride of Different Fertilization Patterns on Maize Yield and Yield Components

[Objective] To understand the application effects of urea ammonium chloride fertilizer on maize production. [Methods] A field plot experiment was conducted to study the effects of urea ammonium chloride of different fertilization patterns on summer maize yield and yield components. [Results] Urea ammonium chloride had a long fertilizer effect and the same yield-increasing effect with urea, which could im- prove the agronomic traits and economic traits of maize apparently and the applica- tion of urea ammonium chloride with nutrient reduction of 40% （namely just use urea ammonium chloride equaled 60% pure nitrogen）, had the same yield-increasing effect with urea of traditional fertilization patterns, and input-output ratio was high and the economic benefit was remarkable. [Conclusion] To provide scientific theoretical direc- tion for large area popularization and application of urea ammonium chloride.

Interaction of NPK Fertilizers During Their Transformation in Soils: Ⅲ. Transformations of Monocalcium Phosphate

Interactions of N, P and K fertilizers in soil-plant systems are widelyrecognized. This study focused on the transformations of monocalcium phosphate (Ca(H_2PO_4)_2) (MCP)with co-application of ammonium and potassium fertilizers in three different soils. The resultsshowed that after 1 d incubation a large portion of the MCP applied in the paddy, calcareous and redsoils became the water-insoluble form and the recoveries of P applied as Olsen P varied greatly inthese three soils. Application of ammonium sulfate ((NH_4)_2SO_4) (AS) or potassium chloride (KCl)reduced WSP significantly the soils with AS more effective than KCl in the calcareous soil, whilethe reverse occurred in the red soil. Meanwhile, in the paddy soil, co-application of the twofertilizers reduced WSP more than when the fertilizers were applied individually. The co-applicationof AS with MCP in the paddy and calcareous soils significantly reduced Olsen P, but the oppositeoccurred in the red soil. The experiment on the effect of different accompanying anions showed thatthe ammonium fertilizers (PNCl and PNS) reduced WSP more effectively than the correspondingpotassium fertilizers (PKCl and PKS) in the calcareous soil due to the difference of the cations,whereas in the red soil, the chlorides reduced WSP more effectively than the sulfates. Overall,co-application of ammonium or potassium fertilizers with MCP significantly decreased availability ofP from MCP during its transformation in soils, especially when MCP was applied in combination withammonium in the calcareous soil.