| 1. |
- Yu, ChaoQing, et al.
(författare)
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Managing nitrogen to restore water quality in China
- 2019
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Ingår i: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 567:7749, s. 516-520
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Tidskriftsartikel (refereegranskat)abstract
- The nitrogen cycle has been radically changed by human activities(1). China consumes nearly one third of the world's nitrogen fertilizers. The excessive application of fertilizers(2,3) and increased nitrogen discharge from livestock, domestic and industrial sources have resulted in pervasive water pollution. Quantifying a nitrogen 'boundary'(4) in heterogeneous environments is important for the effective management of local water quality. Here we use a combination of water-quality observations and simulated nitrogen discharge from agricultural and other sources to estimate spatial patterns of nitrogen discharge into water bodies across China from 1955 to 2014. We find that the critical surface-water quality standard (1.0 milligrams of nitrogen per litre) was being exceeded in most provinces by the mid-1980s, and that current rates of anthropogenic nitrogen discharge (14.5 +/- 3.1 megatonnes of nitrogen per year) to fresh water are about 2.7 times the estimated 'safe' nitrogen discharge threshold (5.2 +/- 0.7 megatonnes of nitrogen per year). Current efforts to reduce pollution through wastewater treatment and by improving cropland nitrogen management can partially remedy this situation. Domestic wastewater treatment has helped to reduce net discharge by 0.7 +/- 0.1 megatonnes in 2014, but at high monetary and energy costs. Improved cropland nitrogen management could remove another 2.3 +/- 0.3 megatonnes of nitrogen per year-about 25 per cent of the excess discharge to fresh water. Successfully restoring a clean water environment in China will further require transformational changes to boost the national nutrient recycling rate from its current average of 36 per cent to about 87 per cent, which is a level typical of traditional Chinese agriculture. Although ambitious, such a high level of nitrogen recycling is technologically achievable at an estimated capital cost of approximately 100 billion US dollars and operating costs of 18-29 billion US dollars per year, and could provide co-benefits such as recycled wastewater for crop irrigation and improved environmental quality and ecosystem services.
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| 2. |
- Huang, He, et al.
(författare)
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Material informatics for uranium-bearing equiatomic disordered solid solution alloys
- 2021
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Ingår i: Materials Today Communications. - : Elsevier BV. - 2352-4928. ; 29
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Tidskriftsartikel (refereegranskat)abstract
- Near-equiatomic, multi-component alloys with disordered solid solution phase (DSSP) are associated with outstanding performance in phase stability, mechanical properties and irradiation resistance, and may provide a feasible solution for developing novel uranium-based alloys with better fuel capacity. In this work, we build a machine learning (ML) model of disordered solid solution alloys (DSSAs) based on about 6000 known multicomponent alloys and several materials descriptors to efficiently predict the DSSAs formation ability. To fully optimize the ML model, we develop a multi-algorithm cross-verification approach in combination with the SHapley Additive exPlanations value (SHAP value). We find that the Delta S-C, Lambda, Phi(s), gamma and 1/Omega, corresponding to the former two Hume - Rothery (H - R) rules, are the most important materials descriptors affecting DSSAs formation ability. When the ML model is applied to the 375 uranium-bearing DSSAs, 190 of them are predicted to be the DSSAs never known before. 20 of these alloys were randomly synthesized and characterized. Our predictions are in-line with experiments with 3 inconsistent cases, suggesting that our strategy offers a fast and accurate way to predict novel multi-component alloys with high DSSAs formation ability. These findings shed considerable light on the mapping between the material descriptors and DSSAs formation ability.
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| 3. |
- Cheng, Jie, et al.
(författare)
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Preparation of Surface Modified Ceria Nanoparticles as Abrasives for the Application of Chemical Mechanical Polishing (CMP)
- 2020
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Ingår i: ECS Journal of Solid State Science and Technology. - : ELECTROCHEMICAL SOC INC. - 2162-8769 .- 2162-8777. ; 9:2
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Tidskriftsartikel (refereegranskat)abstract
- In this study, a method to improve the chemical mechanical polishing (CMP) performance of ceria as abrasive particles was proposed. Surface doping of ceria nanoparticles was realized by incipient impregnation method, in order to improve its valance change properties (Ce3+/Ce4+). This study presents detailed characterization of the lanthanide-doped CeO2 by both experimental methods and density functional theory (DFT) calculation. The dispersion stability of the doped ceria nanoparticles in CMP slurries are investigated. Results show that the doped CeO2 nanoparticles exhibit more oxygen vacancies and higher content of Ce3+ compared with the pristine CeO2. Good dispersion stability of the doped CeO2 nanoparticles could be achieved by adding dispersants in the CMP slurries.
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| 4. |
- Cheng, Jie, et al.
(författare)
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RE (La, Nd and Yb) doped CeO2 abrasive particles for chemical mechanical polishing of dielectric materials : Experimental and computational analysis
- 2020
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Ingår i: Applied Surface Science. - : ELSEVIER. - 0169-4332 .- 1873-5584. ; 506
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Tidskriftsartikel (refereegranskat)abstract
- Ce3+ in CeO2, rather than Ce4+, is believed to provide assistance to the breaking up of Si-O bond during chemical mechanical polishing (CMP) of silica. In the paper, lanthanide metals (La, Nd and Yb) doped CeO2 nanoparticles were synthesized by modified incipient impregnation method in order to improve the content of Ce3+ in CeO2 as polishing. X-ray photoelectron spectroscopy (XPS) experiments and density function theory (DFT) calculation demonstrate this approach could achieve surface doping of CeO2 nanoparticles, and facilitates the formation of oxygen vacancy and Ce3+ content. CMP experiments show that the polishing rate and the surface quality of silica wafer are obviously improved by using the doped CeO2 as abrasive particles. Especially for Nd/CeO2, content of Ce3+ increases from 0.146 to 0.235, the polishing rate of silica is accelerated by 29.6% in alkaline slurries, and a better surface quality (Sa = 9.6 angstrom) is obtained.
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| 5. |
- Huang, Shuo, et al.
(författare)
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Thermo-elastic behavior of hexagonal Sc-Ti-Zr-Hf high-entropy alloys
- 2022
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Ingår i: Journal of Physics D. - : IOP Publishing. - 0022-3727 .- 1361-6463. ; 55:23
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Tidskriftsartikel (refereegranskat)abstract
- Recent advances in tuning the long-standing strength-ductility tradeoff have drawn attention to high-entropy alloys (HEAs), and the appearance of hexagonal close-packed (hcp) structures has been emphasized. However, few studies have explored the elastic moduli of hcp HEAs, which is of prime importance for improved understanding of the outstanding mechanical properties. In this work, we focus on a set of equiatomic rare-earth-free HEAs with hcp structures, i.e. ScTiZr, ScTiHf, ScZrHf, TiZrHf, and ScTiZrHf, and their thermo-elastic properties are studied using quantum mechanical first-principles methods. It is found that, for all considered HEAs, the hexagonal axial ratio shows a weak dependence on the temperature effect, and the thermal expansion coefficient remains almost unchanged above room temperature. From the calculated temperature-dependent single-crystal elastic constants, we analyzed the mechanical stability, elastic anisotropy, and derived polycrystalline moduli. Results indicate that the present HEAs exhibit rather high elastic isotropy and large elastic softening resistance. The ab initio predicted Young's modulus, shear modulus, and specific modulus do not obey the rule of mixture, which indicates that there exists a strong intrinsic hardening effect in all of the considered HEAs. The calculated results are in good agreement with the available experimental measurements.
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| 6. |
- Li, Bo, et al.
(författare)
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Effects of surface roughness and shear processes on solute transport through 3D crossed rock fractures
- 2023
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Ingår i: International Journal of Rock Mechanics And Mining Sciences. - : Elsevier BV. - 1365-1609 .- 1873-4545. ; 170
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Tidskriftsartikel (refereegranskat)abstract
- The influences of surface roughness and shear processes on fluid flow and solute transport through three-dimensional (3D) crossed rock fractures, a vital element of fracture networks, were systematically investigated. Surfaces of tensile fractures created by splitting granite and sandstone samples along its two orthogonal central axes were optically scanned to generate rough-walled crossed fracture models. Shearing processes on the models were realized by assigning experimentally measured normal and shear displacements to one fracture while fixing the other. Fluid flow and solute transport through the models were numerically simulated taking into account different combinations of inlets and outlets, in which distilled water and solution are injected into the two inlets, respectively. The results show that compared to the parallel-plate model, the rough-walled crossed fracture model exhibits obvious flow channelization and fluid redistribution at the intersection, significantly promoting the mixing. The shear process affects the mixing at the intersection as it induces dilation and geometric change of the intersection. Increasing shear displacement can either enhance or reduce the mixing depending on combinations of the inlets and outlets, and the mixing ratio is controlled by the aperture difference between two outlet branches and the surface roughness. Effects of surface roughness, shear displacement and shear-induced dilation on the mixing ratio are quantified, upscaling of which can be potentially useful for field-scale characterization of solute transport in fractured systems.
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| 7. |
- Li, Qin, et al.
(författare)
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Dynamics inside the cancer cell attractor reveal cell heterogeneity, limits of stability, and escape
- 2016
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 113:10, s. 2672-2677
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Tidskriftsartikel (refereegranskat)abstract
- The observed intercellular heterogeneity within a clonal cell population can be mapped as dynamical states clustered around an attractor point in gene expression space, owing to a balance between homeostatic forces and stochastic fluctuations. These dynamics have led to the cancer cell attractor conceptual model, with implications for both carcinogenesis and new therapeutic concepts. Immortalized and malignant EBV-carrying B-cell lines were used to explore this model and characterize the detailed structure of cell attractors. Any subpopulation selected from a population of cells repopulated the whole original basin of attraction within days to weeks. Cells at the basin edges were unstable and prone to apoptosis. Cells continuously changed states within their own attractor, thus driving the repopulation, as shown by fluorescent dye tracing. Perturbations of key regulatory genes induced a jump to a nearby attractor. Using the Fokker-Planck equation, this cell population behavior could be described as two virtual, opposing influences on the cells: one attracting toward the center and the other promoting diffusion in state space (noise). Transcriptome analysis suggests that these forces result from high-dimensional dynamics of the gene regulatory network. We propose that they can be generalized to all cancer cell populations and represent intrinsic behaviors of tumors, offering a previously unidentified characteristic for studying cancer.
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| 8. |
- Li, Suyang, et al.
(författare)
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One-pot fabrication of Mo1-xWxS2 alloy nanosheets as SERS substrates with highly Raman enhancement effect and long-term stability
- 2022
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Ingår i: Spectrochimica Acta Part A - Molecular and Biomolecular Spectroscopy. - : Elsevier BV. - 1386-1425 .- 1873-3557. ; 279, s. 121465-
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Tidskriftsartikel (refereegranskat)abstract
- A new Mo1-xWxS2 two-dimensional nanosheets were prepared by the one-pot method. After certain Mo atoms in MoS2 were replaced by W ones in a hydrothermal reduction procedure, Mo1-xWxS2 was formed on the Mo foil. Well enhanced Mo1-xWxS2 nanosheets were prepared when the sodium tungstate concentration got under control. Various characterizations were carried out, which indicate that Mo1-xWxS2 nanosheets with good crystallinity. Compared with MoS2, the Raman intensity of Rhodamine 6G (10-6 M) was amplified by 1.7 times with Mo1-xWxS2 nanosheets as the substrate. The characteristic Raman peaks could still be clearly distinguished until the concentration of Rhodamine 6G (R6G), Methylene blue (MB) and Crystal violet (CV) down to 10-8, 10-8 and 10- 7 M, respectively. With abundant edge active sites that facilitate charge transfer, Mo1-xWxS2 nanosheets could better enhance SERS signals of target detection molecules and get a good linear relationship exists within the concentration and Raman peak strength. In addition, R6G SERS detection also shows excellent reproducibility and long-term stability of this TMDs SERS substrate.
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| 9. |
- Liu, Dong, et al.
(författare)
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Nitrogen-Doped MoS2/Ti3C2TX Heterostructures as Ultra-Efficient Alkaline HER Electrocatalysts
- 2021
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 60:13, s. 9932-9940
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Tidskriftsartikel (refereegranskat)abstract
- Molybdenum disulfide (MoS2) is intrinsically inert for the hydrogen evolution reaction (HER) in alkaline media due to its electronic structures. Herein, we tune the electronic structures of MoS2 by a combined strategy of post-N doping coupled with the synergistic effect of Ti3C2TX. The as-prepared N-doped MoS2/Ti3C2TX heterostructures show remarkable alkaline HER activity with an over-potential of 225 mV at 140 mA cm(-2), which ranks the N-doped MoS2/Ti3C2TX heterostructures among the best MoS2/MXene-based electrocatalysts reported for alkaline HER. The first-principles calculations indicate that the N doping can enhance the activation of nearby S sites of MoS2/Ti3C2TX and thus promote the HER process. This strategy provides a promising way to develop high-efficiency MoS2/MXene heterostructure catalysts for alkaline HER.
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| 10. |
- Teng, Fei, et al.
(författare)
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Automatic Medical Code Assignment via Deep Learning Approach for Intelligent Healthcare
- 2020
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Ingår i: IEEE journal of biomedical and health informatics. - : Institute of Electrical and Electronics Engineers (IEEE). - 2168-2194 .- 2168-2208. ; 24:9, s. 2506-2515
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Tidskriftsartikel (refereegranskat)abstract
- With the development of healthcare 4.0, there has been an explosion in the amount of data such as image, medical text, physiological signals, lab tests, etc. Among them, medical records provide a complete picture of the associated clinical events. However, the processing of medical texts is difficult because they are structurally free, diverse in style, and have subjective factors. Assigning metadata codes from the International Classification of Diseases (ICD) presents a standardized way of indicating diagnoses and procedures, so it becomes a mandatory process for understanding medical records to make better clinical and financial decisions. Such a manual encoding task is time-consuming, error-prone and expensive. In this paper, we proposed a deep learning approach and a medical topic mining method to automatically predict ICD codes from text-free medical records. The result of the F1 score on Medical Information Mart for Intensive Care (MIMIC-III) dataset increases by 5% over the state of art. It also suitable for multiple ICD versions and languages. For the specific disease, atrial fibrillation, the F1 score is up to 96% and 93.3% using in-house ICD-10 datasets and MIMIC-III datasets, respectively. We developed an Artificial Intelligence based coding system, which can greatly improve the efficiency and accuracy of human coders, and meanwhile accelerate the secondary use for clinical informatics.
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