Bauxite residue is a highly alkaline byproduct which is routinely discarded at residue disposal areas. Improving soil formation process to revegetate the special degraded lands is a promising strategy for sustainable ...Bauxite residue is a highly alkaline byproduct which is routinely discarded at residue disposal areas. Improving soil formation process to revegetate the special degraded lands is a promising strategy for sustainable management of the refining industry. A laboratory incubation experiment was used to evaluate the effects of gypsum and vermicompost on stable aggregate formation of bauxite residue. Aggregate size distribution was quantified by fractal theory, whilst residue microstructure was determined by scanning electron microscopy and synchrotron-based X-ray micro-computed tomography. Amendments addition increased the content of macro-aggregates(> 250 μm) and enhanced aggregate stability of bauxite residue. Following gypsum and vermicompost addition, fractal dimension decreased from 2.84 to 2.77, which indicated a more homogeneous distribution of aggregate particles. Images from scanning electron microscopy and three-dimensional microstructure demonstrated that amendments stimulate the formation of improved structure in residue aggregates. Pore parameters including porosity, pore throat surface area, path length, and path tortuosity increased under amendment additions. Changes in aggregate size distribution and microstructure of bauxite residue indicated that additions of gypsum and vermicompost were beneficial to physical condition of bauxite residue which may enhance the ease of vegetation.展开更多
A column leaching experiment was used to investigate the efficacy of amendments on their ability to remove alkaline anions and metal ions from bauxite residue leachates.Treatments included,simulated acid rain (AR),pho...A column leaching experiment was used to investigate the efficacy of amendments on their ability to remove alkaline anions and metal ions from bauxite residue leachates.Treatments included,simulated acid rain (AR),phosphogypsum + vermicompost (PVC),phosphogypsum + vermicompost + simulated acid rain (PVA),and biosolids + microorganisms (BSM) together with controls (CK).Results indicated that amendment could effectively reduce the leachate pH and EC values,neutralize OH-,CO32-,HCO3-,and water soluble alkali,and suppress arsenic (As) content.Correlation analysis revealed significant linear correlations with pH and concentrations of OH-,CO32-,HCO3-,water-soluble alkali,and metal ions.BSM treatment showed optimum results with neutralizing anions (OH-,CO32-,and HCO3-),water soluble alkali,and removal of metal ions (Al,As,B,Mo,V,and Na),which was attributed to neutralization from the generation of small molecular organic acids and organic matter during microbial metabolism.BSM treatment reduced alkaline anions and metal ions based on neutralization reactions in bauxite residue leachate,which reduced the potential pollution effects from leachates on the soil surrounding bauxite residue disposal areas.展开更多
Soil formation and ecological rehabilitation is the most promising strategy to eliminate environmental risks of bauxite residue disposal areas. Its poor physical structure is nevertheless a major limitation to plant g...Soil formation and ecological rehabilitation is the most promising strategy to eliminate environmental risks of bauxite residue disposal areas. Its poor physical structure is nevertheless a major limitation to plant growth. Organic materials were demonstrated as effective ameliorants to improve the physical conditions of bauxite residue. In this study, three different organic materials including straw(5% W/W), humic acid(5% W/W), and humic acidacrylamide polymer(0.2% and 0.4%, W/W) were selected to evaluate their effects on physical conditions of bauxite residue pretreated by phosphogypsum following a 120-day incubation experiment. The proportion of 2-1 mm macro-aggregates, mean weight diameter(MWD) and geometric mean diameter(GWD) increased following organic materials addition, which indicated that organic materials could enhance aggregate stability. Compared with straw, and humic acid, humic acid-acrylamide polymer application had improved effects on the formation of water-stable aggregates in the residues. Furthermore, organic materials increased the total porosity, total pore volume and average pore diameter, and reduced the micropore content according to nitrogen gas adsorption(NA) and mercury intrusion porosimetry(MIP)analysis, whilst enhancing water retention of the residues based on water characteristic curves. Compared with traditional organic wastes, humic acid-acrylamide polymer could be regarded as a candidate according to the comprehensive consideration of the additive amount and the effects on physical conditions of bauxite residue. These findings could provide a novel application to both Ca-contained acid solid waste and high-molecular polymers on ecological rehabilitation at disposal areas.展开更多
Representing and recognizing protein active sites sequence motif (1D motif) and structural motif (3D motif) is an important topic for predicting and designing protein function. Prevalent methods for extracting and sea...Representing and recognizing protein active sites sequence motif (1D motif) and structural motif (3D motif) is an important topic for predicting and designing protein function. Prevalent methods for extracting and searching 3D motif always consider residue as the minimal unit, which have limited sensitivity. Here we present a new spatial representation of protein active sites, called 'functional-group 3D motif', based on the fact that the functional groups inside a residue contribute mostly to its function. Relevant algorithm and computer program are developed, which could be widely used in the function prediction and the study of structural-function relationship of proteins. As a test, we defined a functional-group 3D motif of the catalytic triad and oxyanion hole with the structure of porcine trypsin (PDB code: 1mct) as the template. With our motif-searching program, we successfully found similar sub-structures in trypsins, subtilisins and α/β hydrolases, which show distinct folds but share展开更多
基金supported by the National Natural Science Foundation of China (No. 41701587)
文摘Bauxite residue is a highly alkaline byproduct which is routinely discarded at residue disposal areas. Improving soil formation process to revegetate the special degraded lands is a promising strategy for sustainable management of the refining industry. A laboratory incubation experiment was used to evaluate the effects of gypsum and vermicompost on stable aggregate formation of bauxite residue. Aggregate size distribution was quantified by fractal theory, whilst residue microstructure was determined by scanning electron microscopy and synchrotron-based X-ray micro-computed tomography. Amendments addition increased the content of macro-aggregates(> 250 μm) and enhanced aggregate stability of bauxite residue. Following gypsum and vermicompost addition, fractal dimension decreased from 2.84 to 2.77, which indicated a more homogeneous distribution of aggregate particles. Images from scanning electron microscopy and three-dimensional microstructure demonstrated that amendments stimulate the formation of improved structure in residue aggregates. Pore parameters including porosity, pore throat surface area, path length, and path tortuosity increased under amendment additions. Changes in aggregate size distribution and microstructure of bauxite residue indicated that additions of gypsum and vermicompost were beneficial to physical condition of bauxite residue which may enhance the ease of vegetation.
基金supported by the National Natural Science Foundation of China(Nos.41701587,41877511)the Open Sharing Fund for the Large-scale Instruments,Euipments of Central South University(No.CSUZC201904)the Fundamental Research Funds for the Central Universities of Central South University
文摘A column leaching experiment was used to investigate the efficacy of amendments on their ability to remove alkaline anions and metal ions from bauxite residue leachates.Treatments included,simulated acid rain (AR),phosphogypsum + vermicompost (PVC),phosphogypsum + vermicompost + simulated acid rain (PVA),and biosolids + microorganisms (BSM) together with controls (CK).Results indicated that amendment could effectively reduce the leachate pH and EC values,neutralize OH-,CO32-,HCO3-,and water soluble alkali,and suppress arsenic (As) content.Correlation analysis revealed significant linear correlations with pH and concentrations of OH-,CO32-,HCO3-,water-soluble alkali,and metal ions.BSM treatment showed optimum results with neutralizing anions (OH-,CO32-,and HCO3-),water soluble alkali,and removal of metal ions (Al,As,B,Mo,V,and Na),which was attributed to neutralization from the generation of small molecular organic acids and organic matter during microbial metabolism.BSM treatment reduced alkaline anions and metal ions based on neutralization reactions in bauxite residue leachate,which reduced the potential pollution effects from leachates on the soil surrounding bauxite residue disposal areas.
基金supported by the National Natural Science Foundation of China(No.42077379)。
文摘Soil formation and ecological rehabilitation is the most promising strategy to eliminate environmental risks of bauxite residue disposal areas. Its poor physical structure is nevertheless a major limitation to plant growth. Organic materials were demonstrated as effective ameliorants to improve the physical conditions of bauxite residue. In this study, three different organic materials including straw(5% W/W), humic acid(5% W/W), and humic acidacrylamide polymer(0.2% and 0.4%, W/W) were selected to evaluate their effects on physical conditions of bauxite residue pretreated by phosphogypsum following a 120-day incubation experiment. The proportion of 2-1 mm macro-aggregates, mean weight diameter(MWD) and geometric mean diameter(GWD) increased following organic materials addition, which indicated that organic materials could enhance aggregate stability. Compared with straw, and humic acid, humic acid-acrylamide polymer application had improved effects on the formation of water-stable aggregates in the residues. Furthermore, organic materials increased the total porosity, total pore volume and average pore diameter, and reduced the micropore content according to nitrogen gas adsorption(NA) and mercury intrusion porosimetry(MIP)analysis, whilst enhancing water retention of the residues based on water characteristic curves. Compared with traditional organic wastes, humic acid-acrylamide polymer could be regarded as a candidate according to the comprehensive consideration of the additive amount and the effects on physical conditions of bauxite residue. These findings could provide a novel application to both Ca-contained acid solid waste and high-molecular polymers on ecological rehabilitation at disposal areas.
文摘Representing and recognizing protein active sites sequence motif (1D motif) and structural motif (3D motif) is an important topic for predicting and designing protein function. Prevalent methods for extracting and searching 3D motif always consider residue as the minimal unit, which have limited sensitivity. Here we present a new spatial representation of protein active sites, called 'functional-group 3D motif', based on the fact that the functional groups inside a residue contribute mostly to its function. Relevant algorithm and computer program are developed, which could be widely used in the function prediction and the study of structural-function relationship of proteins. As a test, we defined a functional-group 3D motif of the catalytic triad and oxyanion hole with the structure of porcine trypsin (PDB code: 1mct) as the template. With our motif-searching program, we successfully found similar sub-structures in trypsins, subtilisins and α/β hydrolases, which show distinct folds but share
