Cosmological Constraints from the Redshift Dependence of the Alcock-Paczynski Effect: Dynamical Dark Energy

Li, Xiao-Dong,Sabiu, Cristiano G.,Park, Changbom,Wang, Yuting,Zhao, Gong-bo,Park, Hyunbae,Shafieloo, Arman,Kim, Juhan,Hong, Sungwook E. American Astronomical Society 2018 The Astrophysical journal Vol.856 No.2

<P>We perform an anisotropic clustering analysis of 1,133,326 galaxies from the Sloan Digital Sky Survey (SDSS-III) Baryon Oscillation Spectroscopic Survey Data Release 12 covering the redshift range 0.15 < z < 0.69. The geometrical distortions of the galaxy positions, caused by incorrect assumptions in the cosmological model, are captured in the anisotropic two-point correlation function on scales of 6-40 h(-1) Mpc. The redshift evolution of this anisotropic clustering is used to place constraints on the cosmological parameters. We improve the methodology of Li et al. to enable efficient exploration of high-dimensional cosmological parameter spaces, and apply it to the Chevallier-Polarski-Linder parameterization of dark energy, w = w(0) + w(a)z/(1 + z). In combination with data on the cosmic microwave background, baryon acoustic oscillations, Type Ia supernovae, and H-0 from Cepheids, we obtain Omega(m) = 0.301 +/- 0.008, w(0) = -1.042 +/- 0.067, and w(a) = -0.07 +/- 0.29 (68.3% CL). Adding our new Alcock-Paczynski measurements to the aforementioned results reduces the error bars by similar to 30%-40% and improves the dark-energy figure of merit by a factor of similar to 2. We check the robustness of the results using realistic mock galaxy catalogs.</P>

Structure and morphological characteristics of polygonal salt crust, the West Juyan Lake, China

Guoming Zhang,Yuting Xiao,Mingzhu Xiang,Chang Hong,Bo-Tao Zhang,Lianyou Liu,Peijun Shi,Jifu Liu 한국지질과학협의회 2022 Geosciences Journal Vol.26 No.3

Polygonal salt crust patches (PSCPs) in modern playas have critical hydrologic implications for arid areas, but the morphology and origin of these polygonal features are under debate. This study investigated the structure and morphological characteristics of crustal landforms in a modern playa located in the West Juyan Lake, western Inner Mongolia of China, through an integrated analysis of high-resolution remote sensing images obtained from Google Earth, pedestrian field surveys, and unmanned aerial vehicle photography. The study area covers approximately 2,650 ha and the number of salt crust patches was 3,491. Across this area, the coverage and number of salt crust patches varied with elevation and sedimentary environment. The results show that the polygonal patch pattern of the salt crust landforms was fractal, and similar polygonal patch perimeter to area ratios and landscape index values prevail in the study area. The wind erosion of material on the surface of the Gobi Desert, a mountain torrent alluvial fan, and material carried by seasonal river water probably provided the provenance of the regional salt crust landforms. The structure and morphological characteristics of salt crust in typical playas of the arid and semiarid region are important for better understanding their composition and sedimentary environment. This study can help reveal relevant information regarding environmental change and provide a reference for saline dust emissions from playas in arid areas.

Effects of Yttrium and Cerium co-substitution on Structures and Magnetic Properties of Nanocrystalline Nd-Fe-B Magnets

Xiaoqiang Yu,Lei He,Yuting Hu,Jiajie Li,Xiao Liu,Yuhan Wang,Chunji Li,Munan Yang,Zhenchen Zhong 한국자기학회 2022 Journal of Magnetics Vol.27 No.2

Cerium-containing (Ce) rare earth magnets with extraordinary cost-effectiveness are widely investigated around the world. However, when the concentration of Ce is much more, the kind of these magnets exhibits very poor thermal stability and overall magnetic properties. To weaken these disadvantages, we take eutectic Y50Ce50 co-substitution alloys into account in this work. Magnetic properties, microstructures and metallurgical behaviors of (Y, Ce, Nd)-Fe-B magnets are systematically researched. For (Y50Ce50)10Nd20Fe68.9B1.1 SPSed permanent magnets, good overall magnetic properties are Hcj = 725 kA/m, Jr = 0.73 T and (BH)max = 81 kJ/m³. It schematically depicts that coarse grain zones and fine grain zones occur during the spark plasma sintering (SPS) process. With the Nd content increasing, the deleterious CeFe₂ phases disappear. In addition, the volume fraction and width of coarse grain zones decrease. Ce-rich and Ce-lean regions are also observed in main phases, while Y and Nd elements are uniformly distributed. TEM results show that Nd and Ce are rich in the grain boundary and Y elements prefer to enter in 2:14:1 main phases. This work is favorable to a balanced utilization of high abundance rare earth elements in Nd-Fe-B magnets.

Model test and numerical simulation on the bearing mechanism of tunnel-type anchorage

Li, Yujie,Luo, Rong,Zhang, Qihua,Xiao, Guoqiang,Zhou, Liming,Zhang, Yuting Techno-Press 2017 Geomechanics & engineering Vol.12 No.1

The bearing mechanism of tunnel-type anchorage (TTA) for suspension bridges is studied. Model tests are conducted using different shapes of plug bodies, which are circular column shape and circular truncated cone shape. The results show that the plug body of the latter shape possesses much larger bearing capacity, namely 4.48 times at elastic deformation stage and 4.54 times at failure stage compared to the former shape. Numerical simulation is then conducted to understand the mechanical and structural responses of plug body and surrounding rock mass. The mechanical parameters of the surrounding rock mass are firstly back-analyzed based on the monitoring data. The calculation laws of deformation and equivalent plastic strain show that the numerical simulation results are rational and provide subsequent mechanism analysis with an established basis. Afterwards, the bearing mechanism of TTA is studied. It is concluded that the plug body of circular truncated cone shape is able to take advantage of the material strength of the surrounding rock mass, which greatly enhances its bearing capacity. The ultimate bearing capacity of TTA, therefore, is concluded to be determined by the material strength of surrounding rock mass. Finally, recommendations for TTA design are proposed and discussed.

Magnetite-based Biochar Coupled with Binary Oxidants for the Effective Removal of Mixed Dye from Wastewater

Mingxia Yu,Huosheng Li,Keke Li,Yuting Li,Fengli Liu,Gaosheng Zhang,Tangfu Xiao,Ping Zhang,Hongguo Zhang,Jianyou Long 한국섬유공학회 2022 Fibers and polymers Vol.23 No.2

Decolorization and organic degradation of wastewater containing multiple dyes are still challenging inwastewater treatment. Magnetic biochar coupled with advanced oxidation is a potential solution to this issue. In this study,a series of magnetite-based biochar composites (Fe3O4@C) was prepared and compared for the removal of mixed dyes,including methyl orange (MO), rhodamine B (RhB), methylene blue (MB), and an organic macromolecule, humic acid(HA). The pyrolysis of watermelon rinds followed by precipitation of Fe3O4 onto the biochar was selected as the optimummethod to prepare an adsorbent and catalyst to couple binary oxidants (hypochlorite and persulfate) for color and totalorganic carbon removal. Persulfate was prone to degrade HA and MB, while hypochlorite was inclined to oxidize MO andRhB. Fe3O4@C exhibited better dye removal performance in coupling with binary oxidants than with a single oxidant. Formixed dye solutions with an initial concentration of 50 mg/l for each dye, the highest TOC (57.24±3.17 %) and the colorremoval efficiencies (94.13±1.68 %) for the mixed dye solution were achieved at a sorbent dosage of 1 g/l and an oxidantdosage of 5 mmol/l for both hypochlorite and persulfate. Multiple free radicals, including hydroxyl radicals, sulfateradicals, and hypochlorite-induced radicals, play critical roles in the degradation of mixed dyes and color removal. Theregeneratibility and reutilization of the magnetic Fe3O4@C composite were effective and stable. The results obtained inthis study show that the combined Fe3O4@C and binary oxidants technique is promising for the treatment of multi-dyewastewater.

Removal of Microcystis aeruginosa and control of algal organic matters by potassium ferrate(VI) pre-oxidation enhanced Fe(II) coagulation

Jihao Zhou,Zhiwei Zhao,Jie Liu,Wei Peng,Xia Peng,Yuting Han,Ping Xiao 한국화학공학회 2019 Korean Journal of Chemical Engineering Vol.36 No.10

The problem of cyanobacteria blooms during potable water production has generated wide concern. Ferrate( VI) serving as a pre-oxidation tactic was first applied to enhance conventional Fe(II) coagulation for Microcystis aeruginosa-laden water treatment at lab scale. Results demonstrated that ferrate(VI) pre-oxidation could successfully destabilize algae cells through destroying the protective organic layer. The residual ferrate(VI) together with post-added Fe(II) could provoke a comproportionation reaction, where large amounts of Fe hydrolyzates [Fe(OH)3] are formed. The in-situ Fe(OH)3 with abundant reactive surface is responsible for the promotion of flocs growth by facilitating the clustering and cross-linking of algal organic matters (AOM) and cyanobacteria cells, simultaneously resulting in satisfactory reductions in OD680, turbidity and UV254. Overdose of ferrate(VI) could cause severe cell destruction along with the release of intracellular organic matter (IOM), which may impair the water quality by increasing the concentration of dissolved organic carbon (DOC) and the disinfection by-products formation potential (DBPFP). Meanwhile, considering the Fe residual in settled water, the optimal ferrate(VI) dose (20 μM) and Fe(II) dose (80 μM) were proposed. Besides, the synergistic effect of both the degradation by ferrate(VI) and the adsorption by in-situ Fe(OH)3 contributed to the removal of DOC and Microcystin-LR. This study suggests that ferrate(VI) might be a potential candidate for pre-treatment to assist Fe(II) coagulation when addressing algae-laden water.