Search

Herein, a novel composite of g‐C3N4 and silver nanoparticles(g‐C3N4@Ag) with enhanced bifunctional catalytic activity through chemical etching is reported. A kind of g‐C3N4@Ag composite by one‐pot route, then treated the product with sodium borohydride (NaBH4) solution for a certain time is first synthesized. The property and morphology of the g‐C3N4@Ag composite changed greatly after the treatment. Compared with the pristine g‐C3N4@Ag composite, the NaBH4‐etching endowed g‐C3N4@Ag composite (RACN) with smoother two‐dimensional plane structure, as well as an extension of the conjugate system which originating from the stronger chemical connection between the Ag nanoparticles and g‐C3N4. Furthermore, research results indicated that the RACN showed superior broad‐spectrum catalytic performance for the reduction of aromatic nitro compounds, and the catalytic efficiency of the RACN is enhanced dozens of times by the treatment. Moreover, the photocatalytic activity of the RACN is also greatly improved. This discovery provides an efficient and facile method toward the enhancement of catalytic activity of semiconductor and metal nanoparticle composites by chemical etching. [ABSTRACT FROM AUTHOR]

A complex two-dimensional hexagonal photonic crystal consisting of silicon (Si) and silica (SiO2) cylinders embedded in the air background is proposed to achieve the effect of all-angle negative refraction imaging. Compared with normal hexagonal-lattice photonic crystals consisting of Si, the reduction of symmetry of the complex photonic crystal results in a large band gap between the second energy band and the third energy band, whereas in a normal hexagonal photonic crystal there is no gap between these two bands. Furthermore, the depressed energy band structures provide advantages to realize all-angle left-handed negative refraction similar to metamaterials. The far-field superlens imaging with an effective refractive index of -1 was demonstrated theoretically in the infrared region at the frequency of 200 THz. We also showed the far-field subwavelength resolution for imaging of two point sources with a distance of 0.66λ. [ABSTRACT FROM AUTHOR]

In this paper, a two-dimensional square photonic crystal (PC) with superconductor cylinders is proposed to realize tunable negative refraction. Based on the dependence of the superconductors’ permittivity on temperatures, photonic band structures thus negative refraction could be tuned by temperatures, whereby the refractive angle could be scanned from positive to negative. The feasibility of the PC operating in infrared and visible regions was discussed. The tunability resulted from the lattice, superconductors, operating frequency, and incident angle may lead the PC to great promise in photoelectronics and superconductor electronic applications. [ABSTRACT FROM AUTHOR]

Purpose: Nitrifiers and denitrifiers are the key drivers of N cycling in paddy soil. Little is known about the effects of different fertilization methods, especially side bar fertilization, on the community of nitrifiers and denitrifiers in paddy soils. Here we assess the relationships between soil physicochemical properties, denitrification and nitrification activities, and the underlying microbial communities in a surface layer of paddy field soil treated with different fertilization methods. Materials and methods: Soil was unfertilized (control), treated with conventional chemical fertilizer (CF), CF plus pig manure (MC), or slow-release fertilizer (SR), or by slow-release side bar fertilization (SB). Soil was sampled after one season of early and late rice growth. We determined soil physicochemical properties, potential nitrification rates (PNR), and denitrification enzyme activities (DEA). Ammonia-oxidizing archaeal (AOA) and bacterial (AOB) communities were assessed via their ammonia monooxygenase ( amoA) genes, and denitrifiers via nitrite reductases ( nirK and nirS) and nitrous oxide reductase ( nosZ). Quantitative PCR was used to assess gene abundance, terminal restriction fragment polymorphism (T-RFLP) to investigate fertilization effects on microbial communities, and clone library sequencing and phylogenetic analysis to explore the taxonomic diversity of the nitrifiers and denitrifiers. Results: Fertilization significantly increased the amount of NH -N in the soil of SB and MC treatments, whereas MC lowered the NO -N level. DEA was higher for MC and CF than the other treatments. The PNR in MC-treated soil was significantly lower than that in CF-treated soil. There were no significant differences in AOA and nirS copy numbers; however, nirK and nosZ copy numbers were higher for MC compared with CF. The number of AOA terminal restriction fragments (TRFs) increased significantly with N addition and reached the highest level for SB, whereas the number of AOB TRFs did not change significantly between treatments. Similarly, the number of nirK TRFs increased under fertilization, with the highest number obtained for SR; however, no significant change was observed for nirS and nosZ TRFs across different treatments, except for their relative abundance. All AOA amoA genotypes were in archaeal group 1.1b, whereas 95% AOB were in Nitrosospira cluster 3a. More than 40% of nirS OTUs were affiliated with Herbaspirillum, a key N-cycle player in this paddy soil. Conclusions: The SB and MC treatments had significant effects on soil N, DEA, and PNR levels, and affected the community of N-functional microbes. SB in combination with pig manure would contribute to the improvement of paddy soil fertility. [ABSTRACT FROM AUTHOR]

Abstract: Multicomponents mixture in the procedure of ceramic preparation is an important procedure, but it is difficult as multicomponents are mixed homogeneously in the traditional process. In order to solve this difficult problem, a novel processing (heterogeneous nucleation-and-growth processing) was used to prepare homogeneous distribution powders. Composite coating particles with mullite stoichiometric ratio (consisting of alpha monohydrate bauxite (α-AlO(OH)) cores without aggregation (average particle size 1.23μm) with an outer homogeneous amorphous silica layer) were prepared by heterogeneous nucleation-and-growth processing. Effects of silica content in composite coating particles versus concentration of tetraethylorthosilicate, pH value, reaction time and reaction temperature were studied. A homogeneous amorphous silica layer on α-AlO(OH) cores was confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and zeta-potentials. [Copyright &y& Elsevier]

In order to solve the difficult problem of heterogeneity of different components in the procedure of ceramic preparation, heterogeneous nucleation-and-growth processing is used to prepare the homogeneous distribution powders. Composite coating particles consisting of alpha alumina cores (average particle size 0.57 μm) with an outer amorphous silica layer are prepared by the heterogeneous nucleation-and-growth processing. The amorphous silica layer on cores is confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and zeta-potential measurement. Effects of silica content in composite coating particles versus concentration of tetraethylorthosilicate (TEOS), pH value, reaction time and reaction temperature are studied. [Copyright &y& Elsevier]