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Iron ore and manganese ore were used as substrate of constructed wetlands (CWs) to enhance nitrogen (N) removal. However, the N purification performance in CWs filled with iron or manganese ore under antibiotics stress needs further study. In this study, three groups of CWs filled with river sand, limonite (a kind of iron ore), and manganese ore sand were constructed, which were named as C-CWs, Fe-CWs, and Mn-CWs, respectively. The effect and mechanism of the composite antibiotics sulfamethoxazole (SMX) and trimethoprim (TMP) on N removal in CWs were investigated. While the addition of SMX and TMP inhibited about 40% nitrification and promoted about 25% denitrification in all CWs, Fe-CWs and Mn-CWs always had better N removal performance than C-CWs. Changes in microbial community structure in CWs indicated that the better N removal performance in Fe-CWs and Mn-CWs was attributed to the presence of more abundant and diverse N-associated bacteria, especially Fe- and Mn-driven autotrophic denitrifying bacteria. What's more, the addition of iron ore or manganese ore contributed to the better N removal performance with highest relative abundance of N-transferring bacteria under antibiotics stress. [ABSTRACT FROM AUTHOR]

In order to improve the anti-corrosive ability of a Ni-SiC nanocoating, a jet electrodeposition technique was used to prepare a Ni-SiC nanocoating on the substrate of a Q235 steel surface. Using FLUENT software to simulate the effects of different nozzle diameters on the jet rate and kinetic energy parameters of the plating solution, the surface morphology, microstructure, and corrosion behaviors of the jet-electrodeposited Ni-SiC nanocoatings prepared with different nozzle diameters were examined using scanning electron microscopy, transmission electron microscopy, x-ray diffraction, and an electrochemical workstation. The kinetic energy (543 kg m2/s2) and jet rate (113 m/s) of the plating fluid were maximized using a nozzle diameter of Φ8 mm. Results indicate that the surface structure of the Ni-SiC nanocoating prepared using a nozzle diameter of Φ8 mm presented compact, homogeneous, and abundant SiC particles embedded into the Ni-SiC nanocoating, and the average diameters of the Ni and SiC particles were 76.4 nm and 33.2 nm, respectively. This proved that the diameter of the nozzle had a significant influence on the anti-corrosive properties of the Ni-SiC nanocoating, where a nozzle diameter of Φ8 mm was shown to be optimal. It has been shown that nozzle diameter improves kinetic energy and jet rate of the plating fluid, thereby improving anti-corrosive properties and generating a compact and uniform microstructure. [ABSTRACT FROM AUTHOR]

Purpose: The discovery of comammox Nitrospira being capable of complete oxidising ammonia to nitrate radically challenged the conventional concept of two-step nitrification. However, the response of comammox Nitrospira to nitrification inhibitors (NIs) and their role in soil nitrification remain largely unknown, which has hindered our ability to predict the efficiency of NIs in agroecosystems. Materials and methods: We evaluated the effect of four NIs, 2-chloro-6-(trichloromethyl) pyridine (nitrapyrin), 3,4-dimethylpyrazole phosphate (DMPP), allylthiourea (ATU) and dicyandiamide (DCD) on the growth of comammox Nitrospira, ammonia-oxidising archaea (AOA) and ammonia-oxidising bacteria (AOB) in two pasture and arable soils. Results and discussion: The amendment of nitrogen fertiliser significantly increased soil nitrate concentrations over time, indicating a sustaining nitrification activity in both soils. The addition of all the four NIs effectively reduced the production of nitrate in both soils, but to varying degrees during incubation. The abundances of comammox Nitrospira clade A were significantly increased by addition of nitrogen fertilisers and significantly impeded by the four NIs in the pasture soil, but their abundances were only remarkably hindered by nitrapyrin in the arable soil. All the four NIs obviously inhibited the AOB abundances in both soils. Except for DMPP, the other three NIs effectively suppressed the AOA abundances in both soils. Conclusions: We provided new evidence that growth of comammox Nitrospira clade A can be stimulated by nitrogen fertilisers and inhibited by various nitrification inhibitors, suggesting their potential role in nitrification of agricultural soils. [ABSTRACT FROM AUTHOR]

Carbon steel AISI 1045 (0.45% C) is studied as a model material for rapid nitriding in a salt bath at 660°C (instead of the conventional 560°C). The methods of optical microscopy, x-ray diffraction and measurement of microhardness and corrosion resistance are used to study the microstructure and the phase composition of the nitrided layer. It is shown that salt bath nitriding shortens the process considerably and raises its efficiency; the microhardness and the corrosion resistance grow and the nitride layer acquires a γ′-Fe4N phase. [ABSTRACT FROM AUTHOR]

The appropriate choice of chemical composition of a metallic precursor, which produces the basic structure units in the growth process of nanocrystals, is a high priority in the synthesis of metal-especially Au-nanoparticles. In the present work, Au seeds (prepared by the reduction of Au solution with NaBH4 in the presence of cetyltrimethylammonium bromide (CTAB)) have been used to initiate the growth of Au nanoparticles from two different Au precursors. When an aqueous Au solution prepared in the presence of CTAB micelles was treated with ascorbic acid in the presence of the gold seeds, a high yield (up to 92%) of gold nanoparticles was obtained. By varying the volume of the seed solution with a fixed amount of Au, we can effectively control the morphological transformation of the resulting Au nanoparticles from cubes to octahedra. When an aqueous Au solution was prepared in the presence of CTAB micelles and treated with ascorbic acid in the presence of the gold seeds, smaller yields of Au nanoparticles were obtained. A preliminary growth mechanism has been proposed based on the changes induced by varying the amount of ascorbic acid and the ratio of the concentration of Au to the number of seeds. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]