Application of magnetic adsorbent with silicate and phenyl polymers to adsorb Rhodamine B

The extensive use of Rhodamine B (RhB) for textile, paper, pigment, food, cosmetic, and drug manufacturing and its indiscriminate disposal leads to serious human, biological, and environmental hazards. A magnetic adsorbent with silicate and phenyl polymers (Ph/SiO₂/Fe₃O₄) has been prepared to absorb RhB. The morphology and structure of the adsorbents have been characterized by TGA, XRD, FTIR, and adsorption–desorption measurement. The results revealed that Ph/SiO₂/Fe₃O₄ exhibited a paramagnetic behavior and could easily and quickly be separated from a suspension. The RhB adsorption behavior was almost pH independent due to the adsorption between the phenyl ring of Ph/SiO₂/Fe₃O₄ and RhB by π–π electron-donor–acceptor interactions. The adsorption behavior of RhB adsorption was in good agreement with the Langmuir adsorption isotherm, and the maximum adsorption capacity was 142.186 mg g^?1. Good desorption performance of Ph/SiO₂/Fe₃O₄ showed that this novel magnetic adsorbent cannot only be activated by ethanol extraction process but also reuse by the recovery of magnetic force.     

Dynamic Response and Mechanical Behaviours of Geogrid for High Earth-rockfill Dams

Geotechnical and Geological Engineering - Due to the complexity of the interaction between the geogrid and the soil interface in high earth-rock dams, the method of replacing the grid with steel...     

Investigation of the penetration characteristics of snake skin-inspired pile using DEM

Acta Geotechnica - Snake can perfectly utilize its scales to move. Inspired by the snake scales, this study investigated the characteristics of the snake skin-inspired pile penetration process. Six...     

Trace metals in seawater and copepods in the ocean outfall area off the northern Taiwan coast

The distribution, partitioning and concentrations of trace metals (Cd, Cr, Cu, Fe, Mn, Pb and Zn) in seawater, including dissolved and particulate phases, and in copepods in the ocean outfall area off the northern coast of Taiwan were investigated. Normalization of metal concentrations to the background metal concentration to yield relative enrichment factors (EF), which were used to evaluate the contamination of dissolved and particulate trace metals in seawater around the ocean outfall. The EF results indicated that the outfall area was significantly contaminated by dissolved Fe and Zn, and by particulate Fe, Cr, Cu, Pb and Zn. In addition, most trace metals were chiefly in the particulate phase. The average percentage of total metal concentrations (dissolved plus particulate phases) bound by suspended particulate matter followed the sequence Al(95%) = Mn(95%) > Pb(88%) > Cu(86%) > Fe(72%) > Zn(32%) > Cr(17.5%) > Cd(3.4%). Therefore, metal contamination is better evaluated in solid phase than in the dissolved phase. The concentration ranges of trace metals in the copepods, Temora turbinata, Oncaea venusta and Euchaeta rimana, near the outfall were: Cd, 0.23-1.81 microg g(-1); Cr, 16.5-195 microg g(-1); Cu, 14-160 microg g(-1); Fe, 256-7255 microg g(-1); Mn, 5.5-80.8 microg g(-1); Pb, 2.6-56.2 microg g(-1); Zn, 132-3891 microg g(-1); and Al, 0.21-1.13%. Aluminum, and probably Fe, seemed to be the major elements in copepods. The concentrations of trace metals in copepods, especially Temora turbinata, near the outfall were generally higher than those obtained in the background station. The mean increase in bioconcentration factor of metals in copepods ranged from 4 to 7 and followed the sequence Al(6.4) > Cu(6.2) > Fe(6.0) > Zn(5.7) > Pb(5.6) > Cr(5.5) > Cd(5.1) > Mn(4.7). Therefore, marine copepods in the waters of northern Taiwan can accumulate trace metals over background concentrations and act as contamination indicators.     

Some phenomena of the interaction between vegetation and a atmosphere on multiple scales

This article studies the response of the distribution pattern and the physiological characteristics of the ecosystem to the spontaneous precipitation and the interaction between vegetation and the atmosphere on multiple scales in arid and semi-arid zones, based on measured data of the ecological physiological parameters in the Ordas Plateau of northern China. The results show that the vegetation biomass and the energy use efficiency of photosynthesis are especially sensitive to the annual precipitation; strong and complex interactions exist between the vegetation and the atmosphere on multiple scales leading to supernormal thermal heterogeneity of the underlying surface, the strong vortex movement and turbulence. This study can facilitate understanding of the land surface processes and the influences of global climate change as well as human activities on the human environment in the arid and semi-arid zones. It also aids in improving the parameterization schemes of turbulent fluxes of a heterogeneous underlying surface for land surface processes in climate models.     

The Mg Ⅱ absorption line systems in quasar spectra from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope

Making use of quasar spectra from LAMOST,in the spectral data around the Mg Ⅱ emission lines,research described in this paper has detected 217 Mg Ⅱ narrow absorption lines(NALs) with W_r ~(λ2796)≥3σ_w and W_r~(λ2803)≥ 2σ_w in a redshift range of 0.4554≤z_(abs)≤2.1110.For quasars observed by both LAMOST and SDSS,we find that 135 Mg Ⅱ NALs were obviously observed in the LAMOST spectra,347 Mg Ⅱ NALs were were apparent in the SDSS spectra,and 132 Mg Ⅱ NALs were clearly present in both the SDSS and LAMOST spectra.The missed Mg Ⅱ NALs are likely ascribed to low signal-to-noise ratios of corresponding spectra.Among the Mg 11 NALs obviously observed in SDSS or LAMOST spectra,eight Mg 11 NALs were significantly changed with |ΔW_r ~(λ2796)|≥3σ_w in time intervals of ΔMJD/(1+z_(em))=359-2819 d.     

Effect of nano-MgO on mechanical performance of cement stabilized silty clay

Abstract

A series of direct shear tests were performed on cement-admixed silty clay to investigate the effect of cement content and nano-magnesia (MgO) on its shear strength properties. For each normal stress, shear strength increased with cement content. However, an obvious increment in shear strength was achieved when the cement content was adjusted from 13% to 17%. Both cohesion and friction angle of cemented soil increased with cement content, and exponential function was adopted to correlate both the factors with cement content. For cement content of 10% investigated in this study, the optimum nano-MgO content was 10‰, wherein the cohesion could reach the peak value. The microstructure of the mixture revealed that the structure of the mixture was compacted for the optimum nano-MgO content. However, micro-cracks were formed when the amount of nano-MgO exceeded its optimum content.     

Base cation concentrations in forest litter and topsoil have different responses to climate and tree species along elevational gradients

The forest litter is an essential reservoir of nutrients in forests, supplying a large part of absorbable base cations(BC) to topsoil, and facilitating plant growth within litter-soil system. To characterize elevational patterns of base cation concentrations in the forest litter and topsoil, and explore the effects of climate and tree species, we measured microclimate and collected the forest litter and topsoil(0-10 cm) samples across an elevational range of more than 2000 m(1243 ～ 3316 m a.s.l.),and analyzed the concentrations of BC in laboratory. Results showed that: 1) litter Ca concentration displayed a hump-shaped pattern along the elevational gradients, but litter K and Mg showed saddle-shaped patterns. Soil Ca concentration increased with elevation, while soil K and Mg had no significant changes. 2) Ca concentration in the forest litter under aspen(Populus davidiana) was significantly higher than that in all other species, but in topsoil, Ca concentration was higher under coniferous larch and fir(Larix chinensis and Abies fargesii). Litter K and Mg concentrations was higher under coniferous larch and fir, whereas there were nosignificant differences among tree species in the concentrations of K and Mg in topsoil. 3) Climatic factors including mean annual temperature(MAT), growing season precipitation(GSP) and non-growing season precipitation(NGSP) determined BC concentrations in the forest litter and topsoil. Soil C/N and C/P also influenced BC cycling between litter and soil. Observation along elevations within different tree species implies that above-ground tree species can redistribute below-ground cations, and this process is profoundly impacted by climate. Litter and soil Ca, K and Mg with different responses to environmental variables depend on their soluble capacity and mobile ability.     

无人海洋测绘技术体系构建

随着无人技术的快速发展,无人测绘的时代即将到来。本文分析了无人时代技术特征与海洋测绘发展机遇;讨论了无人海洋测绘新理念,构建了无人海洋测绘技术体系,论述了无人海洋测绘技术关键技术;展望了无人海洋测绘技术发展趋势,及其在海洋经济、海洋可持续发展中的应用前景。