Effects of macromolecular organic acids on reducing inorganic phosphorus fixation in soil.

To improve the availability of inorganic phosphorus (P) in soil, we investigated the role of three macromolecular organic acids (MOAs), including fulvic acid (FA), polyaspartic acid (PA), and tannic acid (TA), in reducing the fixation of inorganic P fertilizer in the soil. AlPO, FePO, and CaH(PO)·5HO crystals were chosen as insoluble phosphate representatives in the soil to simulate the solubilization process of inorganic P by MOAs. The microstructural and physicochemical properties of AlPO, FePO, and CaH(PO)·5HO were determined by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS) before and after treatment of MOAs.

Effect of external electric field on ultraviolet-induced nanoparticle colloid jet machining.

Electric field enhanced ultraviolet (UV)-induced nanoparticle colloid jet machining is proposed to improve the material removal efficiency of UV-induced nanoparticle colloid jet machining by applying an external electric field. The influences of TiOnanoparticle concentration, applied electric field voltage and pH value for the photocatalytic activity of the polishing slurry was investigated by orthogonal experiments. Terephthalic acid (TPA) was used as a fluorescent molecular probe to reflect the relative concentration of hydroxyl radical groups (·OH) in polishing slurry, which directly affects the material removal rate in the UV-induced nanoparticle colloid jet machining process.

Experimental Study on Ultra-Precision Polishing of Ti-6Al-4V by Ultraviolet-Induced Nanoparticle Colloid Jet Machining.

Ti-6Al-4V is widely used in various fields of modern industry, but it is difficult to obtain an ultra-smooth surface of Ti-6Al-4V due to its poor machinability. In this article, ultraviolet-induced (UV-induced) nanoparticle colloid jet machining was utilized to carry out ultra-precision polishing of Ti-6Al-4V to improve the surface quality. The results of infrared differential spectroscopy before and after polishing show that new chemical bonds such as Ti-O-Ti (Al-O-Ti and V-O-Ti) appear on the Ti-6Al-4V workpiece surface, which indicates that the material of Ti-6Al-4V workpiece is removed through the chemical interaction between TiO nanoparticles and workpiece surface in the process of UV-induced nanoparticle colloid jet machining.

Experimental Investigation on the Effects of Photocatalysis in Ultraviolet-Induced Nanoparticle Colloid Jet Machining.

In this paper, ultraviolet (UV)-induced nanoparticle colloid jet machining is proposed to achieve ultrasmooth surface polishing by using the interaction between nanoparticles and the workpiece surface under the action of the ultraviolet field and the hydrodynamic pressure field. In the process of UV-induced nanoparticle colloid jet machining, the effects of photocatalysis on the interaction between nanoparticles and the workpiece surface need to be further studied in order to better understand the polishing process. This paper presents the interaction between TiO nanoparticles and a Si workpiece surface with and without ultraviolet irradiation.

Removal Mechanism Investigation of Ultraviolet Induced Nanoparticle Colloid Jet Machining.

Ultraviolet induced nanoparticle colloid jet machining is a new ultra-precision machining technology utilizing the reaction between nanoparticles and the surface of the workpiece to achieve sub-nanometer ultra-smooth surface manufacturing without damage. First-principles calculations based on the density functional theory (DFT) were carried out to study the atomic material removal mechanism of nanoparticle colloid jet machining and a series of impacting and polishing experiments were conducted to verify the mechanism. New chemical bonds of Ti-O-Si were generated through the chemical adsorption between the surface adsorbed hydroxyl groups of the TiO cluster and the Si surface with the adsorption energy of at least -4.

Study of nitrate leaching and nitrogen fate under intensive vegetable production pattern in northern China.

Because of intensive vegetable production in plastic greenhouses in northern China, the potential risk of nitrate leaching to groundwater is increasingly apparent, threatening ecosystem services and the sustainability of food production. In the present work, nine drainable lysimeters were installed into vegetable fields, with in-situ loamy soils, in Shouguang City of the north China vegetable base. The experiments were conducted to quantify the magnitude and variability of nitrate leaching to groundwater and to access the fate of total fertilizer-N inputs in the area.