Search

The sustainability of aquaculture tailwater plays a key role in the aquaculture industry. Photocatalytic degradation of recalcitrant antibiotics in aquaculture tailwater has emerged as a significant research focus, with gCN-based photocatalysis offering a promising approach. To address the issue of inefficient degradation associated with gCN, melamine was modified using NaCl solution, resulting in the synthesis of NaMe-x with distinctive microstructure through molten salt assistance. The ability of NaMe-x to degrade tetracycline hydrochloride (TC-HCl) was examined, including an analysis of its degradation pathway, intermediate products, mechanism, and toxicity of the by-products. The results demonstrated that NaCl-based precursor modification markedly enhanced the degradation capacity of gCN for TC-HCl, achieving a maximum degradation rate of 0.02214 min−1, which is 2.1 times higher than that of unmodified gCN. LC-MS analysis revealed intermediates at various degradation stages, and two potential pathways for TC-HCl degradation in the presence of NaMe-1 were identified. In this process, ·O2− and ·OH are the reactive radicals that play a dominant role, and their degradation mechanism is thus proposed. It was confirmed by toxicity experiments that the products after the degradation of TC-HCl by NaMe-1 were not significantly toxic to Chlorella vulgaris (p ˃ 0.05). However, it had a significant effect on Vibrio fischeri (p < 0.01). These findings suggest that the synthesis of NaMe-x via melamine precursor modification substantially improves the degradation performance of gCN and enhances the sustainability of aquaculture tailwater. [ABSTRACT FROM AUTHOR]

In this paper, a hybrid complex variable element-free Galerkin (HCVEFG) method is proposed for solving three-dimensional (3D) steady convection–diffusion–reaction equations. By introducing the dimension splitting method (DSM), a 3D convection–diffusion–reaction problem is changed into a series of two-dimensional (2D) ones. For each 2D form, the improved complex variable moving least-squares (ICVMLS) method is applied to obtain the required approximation shape functions, and the penalty method is used to apply the essential boundary conditions, thus we can obtain the 2D discretized equations by using the improved complex variable element-free Galerkin (ICVEFG) method. The finite difference method (FDM) is used in one-dimensional splitting direction. Thus, the final solution formula about the numerical solution for 3D convection–diffusion–reaction problem can be obtained. Three numerical examples show that the HCVEFG algorithm can cut down the CPU cost of the improved element-free Galerkin (IEFG) method greatly for solving 3D steady convection–diffusion–reaction problems. [ABSTRACT FROM AUTHOR]

Abstract.In order to approximate the distribution of chi-squared-type mixtures, Zhang (2005) proposed to use a chi-squared-type random variable of the form α1χd12+β1, where the unknown parameters α1, β1, and d1 are determined by matching the first three cumulants. In this article, we propose a novel method to approximate the distribution of chi-squared-type mixtures by the distribution of a random variable in the form αχd2+β+σξ, where ξ is a standard normal random variable, and the unknown parameters α, β, σ, and d are determined by matching the first four cumulants. The approximating error bound on the distribution functions of the new method approximation is established. The numerical results show that our proposed method can has fewer error bound than some existed methods in some examples. [ABSTRACT FROM AUTHOR]

A rotation of summer tobacco-winter barley-next summer maize (T-B-M) has been suggested by Chinese government programs as an alternative land use practice to replace the conventional tobacco-fallow monoculture (T) and tobacco-barley succession (T-B) management systems. Crop yield in each crop system was recorded from 2010 to 2016 and routine and 454 pyrosequencing approaches were used to evaluate the effects of these cropping systems on organic matter, enzyme activity, and bacterial biomass and community composition within the same soil type. Tobacco leaf yields, barley grains, organic matter, microbial biomass, and enzyme activity (urease, neutral phosphatase, invertase and dehydrogenase) in the soil increased with crop species (but differences were not significant for dehydrogenase activity between T and T-B, and for neutral phosphatase activity between T-B and T-B-M). Indices of richness and diversity of soil bacterial communities also increased as the number of 16S rRNA gene sequences and bacterial phylotypes in the soil increased. The presence of many different bacteria in a soil system may prevent excess reproduction of any single pathogenic bacterium and subsequently reduce the risk of large-scale disease spread. All cropping soils were dominated by Proteobacteria, Acidobacteria, Actinobactria, Bacteroidetes, and unclassified bacteria. Of the 20 predominant bacteria, 13 were commonly found in all soils studied, whereas only four to five were unique in each of the soils examined. This suggests that the presence of those bacteria was more influenced by soil properties than cropping systems in a period of land use. Additional keywords: 454 sequencing, bacteria, cropping regimes. Received 15 August 2018, accepted 27 May 2019, published online 26 July 2019, Introduction Summer tobacco-winter fallow (T) and summer tobacco-winter barley (T-B) are conventional cropping systems and prevail in ethnic areas of Liangshan, Sichuan Province, south-west China. Compared with T monoculture and [...]

The inferior reversibility of Zn metal anode caused by undesired Zn dendrite and severe interfacial side reactions has to be addressed for the commercial application of Zinc ion batteries (ZIBs). Here, a multiple functional sodium benzaldehyde 2,4‐disulfonate(B24DADS) additives with various blocks of polar sulfonate group, Lewis basic aldehyde groups, and hydrophobic benzene ring is proposed to regulate the solvation structure of Zn2+, construct an H2O‐poor and zincophilic dual electric layer structure, and create a passive SEI on the Zn anode surface, thus restaining dendrite growth and interfacial side reactions. Furthermore, uniform deposition mechanics of the Zn are revealed by the synergistic effect of induced deposition, additive‐derived SEI formation, and texture regulation. In addition, Na+ can also limit the growth of zinc dendrites based on electrostatic shielding mechanisms. Therefore, the multifunctional B24DADS additive grants the anode to deliver remarkable electrochemical performance. Under critical test conditions (20 mA cm−2/20 mAh cm−2), the zinc provides superior long cycling (3700 h) with a low polarization voltage (0.02 V). B24DADS containing electrolyte is well matched with manganese dioxide cathode. This effort renders a promising way to explore advanced additives with unique molecular structures for addressing zinc dendrite growth and rampant side effects. [ABSTRACT FROM AUTHOR]

Background: Micronutrient malnutrition affects millions of people due to a lack of Zn and Se., Methods: The process conditions for the manufacture of glycine-chelated sodium selenite (Se-Gly) and zinc sulfate heptahydrate (Zn-Gly) were studied. The effects of ligand concentration, pH, reaction ratio, reaction temperature, and reaction time on fertilizer stability were assessed. The effects of Zn-Gly and Se-Gly on tea plants were determined., Results: Orthogonal experiments showed that the optimal preparation conditions for Zn-Gly (75.80 % Zn chelation rate) were pH 6.0, ligand concentration 4 %, reaction ratio 1:2, reaction time 120 min, reaction temperature 70 ℃. The optimal preparation conditions for Se-Gly (56.75 % Se chelation rate) were pH 6.0, ligand concentration 10%, reaction ratio 2:1, reaction time 40 min, temperature 50 ℃. Each chelate was completely soluble in water and verified by infrared spectroscopy and ultraviolet spectroscopy., Conclusions: Zn-Gly and Se-Gly increased the Zn and Se content in tea plants, and foliar application was more effective than soil application. Combined application of Zn-Gly and Se-Gly was more effective than Zn-Gly or Se-Gly alone. Our findings suggest that Zn-Gly and Se-Gly provide a convenient method of addressing human Zn and Se deficiency.