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Stress-strain relationship and seismic performance of cast-in-situ phosphogypsum.
Zhang, Y, Dai, S, Weng, W, Huang, J, Su, Y, Cai, Y
Journal of applied biomaterials & functional materials. 2017;(Suppl. 1):e62-e68
Abstract
BACKGROUND Phosphogypsum is a waste by-product during the production of phosphoric acid. It not only occupies landfill, but also pollutes the environment, which becomes an important factor restricting the sustainable development of the phosphate fertilizer industry. Research into cast-in-situ phosphogypsum will greatly promote the comprehensive utilization of stored phosphogypsum. The aim of this study was to clarify the mechanical properties of phosphogypsum. METHODS Stress-strain relationships of cast-in-situ phosphogypsum were investigated through axial compressive experiments, and seismic performance of cast-in-situ phosphogypsum walls and aerated-concrete masonry walls were simulated based on the experimental results and using finite element analysis. RESULTS The results showed that the stress-strain relationship fitted into a polynomial equation. Moreover, the displacement ductility index and the energy dissipation index of cast-in-situ phosphogypsum wall were 6.587 and 3.425, respectively. CONCLUSIONS The stress-strain relationship for earthquake-resistant performance of cast-in-situ phosphogypsum walls is better than that of aerated-concrete masonry walls. The curve of stress-strain relationship and the evaluation of earthquake-resistant performance provide theoretical support for the application of cast-in-situ phosphogypsum in building walls.
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2.
QTL meta-analysis of root traits in Brassica napus under contrasting phosphorus supply in two growth systems.
Zhang, Y, Thomas, CL, Xiang, J, Long, Y, Wang, X, Zou, J, Luo, Z, Ding, G, Cai, H, Graham, NS, et al
Scientific reports. 2016;:33113
Abstract
A high-density SNP-based genetic linkage map was constructed and integrated with a previous map in the Tapidor x Ningyou7 (TNDH) Brassica napus population, giving a new map with a total of 2041 molecular markers and an average marker density which increased from 0.39 to 0.97 (0.82 SNP bin) per cM. Root and shoot traits were screened under low and 'normal' phosphate (Pi) supply using a 'pouch and wick' system, and had been screened previously in an agar based system. The P-efficient parent Ningyou7 had a shorter primary root length (PRL), greater lateral root density (LRD) and a greater shoot biomass than the P-inefficient parent Tapidor under both treatments and growth systems. Quantitative trait loci (QTL) analysis identified a total of 131 QTL, and QTL meta-analysis found four integrated QTL across the growth systems. Integration reduced the confidence interval by ~41%. QTL for root and shoot biomass were co-located on chromosome A3 and for lateral root emergence were co-located on chromosomes A4/C4 and C8/C9. There was a major QTL for LRD on chromosome C9 explaining ~18% of the phenotypic variation. QTL underlying an increased LRD may be a useful breeding target for P uptake efficiency in Brassica.
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3.
How the novel integration of electrolysis in tidal flow constructed wetlands intensifies nutrient removal and odor control.
Ju, X, Wu, S, Huang, X, Zhang, Y, Dong, R
Bioresource technology. 2014;:605-613
Abstract
Intensified nutrient removal and odor control in a novel electrolysis-integrated tidal flow constructed wetland were evaluated. The average removal efficiencies of COD and NH4(+)-N were above 85% and 80% in the two experimental wetlands at influent COD concentration of 300 mg/L and ammonium nitrogen concentration of 60 mg/L regardless of electrolysis integration. Effluent nitrate concentration decreased from 2.5mg/L to 0.5mg/L with the reduction in current intensity from 1.5 mA/cm(2) to 0.57 mA/cm(2). This result reveals the important role of current intensity in nitrogen transformation. Owing to the ferrous and ferric iron coagulant formed through the electro-dissolution of the iron anode, electrolysis integration not only exerted a positive effect on phosphorus removal but also effectively inhibited sulfide accumulation for odor control. Although electrolysis operation enhanced nutrient removal and promoted the emission of CH4, no significant difference was observed in the microbial communities and abundance of the two experimental wetlands.
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4.
[Effect of nitrite accumulation on enhanced biological phosphorus removal (EBPR) in A2O process treating domestic wastewater].
Zeng, W, Li, L, Yang, YY, Zhang, Y, Peng, YZ
Huan jing ke xue= Huanjing kexue. 2010;(9):2105-12
Abstract
At normal temperature, short-cut nitrification and denitrification was achieved in a lab-scale A2O process treating low C/N ratio domestic wastewater by controlling DO concentration of 0.3-0.5 mg/L and increasing the internal reflux ratio to decrease the actual aerobic HRT. However, the phosphorus removal in A2O process was deteriorated with the increasing of the nitrite concentration in the effluent. The factors causing phosphorus removal deterioration, such as the influent COD concentrations, temperature, pH and free nitrous acid (FNA) were systematically analyzed. Experimental results showed that the nitrite accumulation resulting from short-cut nitrification affected anaerobic P release and aerobic P uptake. Especially, the higher FNA concentration (HNO2-N 0.002-0.003 mg/L) in the aerobic zone significantly inhibited the aerobic P uptake, which was the major reason causing P removal deterioration. Through adding the carbon sources in influent to enhance anaerobic P release and denitrification, the nitrite and FNA concentrations in the aerobic zone were decreased, and the P removal was recovered. More than 96% of PO4(3-) -P could be removed in A2O process.
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5.
[Spatial variability of farmland soil nutrients at Taihang piedmont].
Zhang, Y, Mao, R, Hu, C, Zhang, J, Zhu, A
Ying yong sheng tai xue bao = The journal of applied ecology. 2004;(11):2049-54
Abstract
By the method of geostatistics, this paper studied the spatial variability of soil nutrients in 30,490 hm2 crop field in Luancheng region and in 15 hm2 experimental field in Luancheng Ecological Agriculture Station of Chinese Academy of Sciences. The results showed that the variation of soil nutrient contents differed obviously, and the semivariograms could be simulated by Gaussian and spherical models with some nugget variances. The limit distance of spatial correlation was 4.2-15.6 km and 112-223 m in Luancheng region and in experimental field, respectively, and the spatial variability of soil organic matter, N, P and K was of semivariance structure. It revealed that there existed a spatial correlation in soil nutrient contents under relatively large-block scale, which made it possible to develop regionalized soil nutrient precision management.