| 1. |
- Liu, Zhenzhong, et al.
(author)
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Study of natural attenuation after acid in situ leaching of uranium mines using isotope fractionation and geochemical data
- 2023
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In: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 865, s. 161033-
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Journal article (peer-reviewed)abstract
- Acid in situ leaching (AISL) is a subsurface mining approach suitable for low-grade ores which does not generate tail-ings, and has been adopted widely in uranium mining. However, this technique causes an extremely high concentra-tion of contaminants at post-mining sites and in the surroundings soon after the mining ceases. As a potential AISL remediation strategy, natural attenuation has not been studied in detail. To address this problem, groundwater collected from 26 wells located within, adjacent, upgradient, and downgradient of a post-mining site were chosen to analyze the fate of U(VI), SO42-, delta 34S, and delta 238U, to reveal the main mechanisms governing the migration and atten-uation of the dominant contaminants and the spatio-temporal evolutions of contaminants in the confined aquifer of the post-mining site. The delta 238U values vary from -0.07 %o to 0.09 %o in the post-mining site and from -1.43 %o to 0.03 %o around the post-mining site. The delta 34S values were found to vary from 3.3 %o to 6.2 %o in the post-mining site and from 6.0 %o to 11.0 %o around the post-mining site. Detailed analysis suggests that there are large differences between the range of isotopic composition variation and the range of pollutants concentration distribution, and the es-timated Rayleigh isotope fractionation factor is 0.9994-0.9997 for uranium and 1.0032-1.0061 for sulfur. The isotope ratio of uranium and sulfur can be used to deduce the migration history of the contaminants and the irreversibility of the natural attenuation process in the anoxic confined aquifer. Combining the isotopic fractionation data for U and S with the concentrations of uranium and sulfate improved the accuracy of understanding of reducing conditions along the flow path. The study also indicated that as long as the geological conditions are favorable for redox reactions, natural attenuation could be used as a cost-effective remediation scheme.
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| 2. |
- Li, Yongmei, et al.
(author)
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Update to the Newly Developed Expression for the Stability Ratio of Colloidal Dispersions
- 2023
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In: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 39:15, s. 5284-5293
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Journal article (peer-reviewed)abstract
- The colloidal stability, one of the basic and important properties of a colloidal dispersion, is commonly evaluated in terms of the stability ratio. In this study, a recently developed expression for the stability ratio is updated, by reformulating the fraction of successful collisions leading to secondary minimum coagulation. The updated formula reinterprets the statistical meaning of the fraction of successful collisions leading to primary or secondary minimum coagulation, ensuring that the total fraction of successful collisions is always less than or equals to 1. It was shown to be superior to the available expressions in accounting for the contribution of the primary and secondary minimum coagulations on the stability ratio. It can well interpret the stability of colloidal dispersions of spherical particles; moreover, it is of great potential to be applied to colloidal dispersions of plate-like particles. In addition, this formula is found to be consistent with the concept of the critical coagulation concentration and well interpret the effects of particle size, counterion valence, surface potential, and Hamaker constant on the colloidal stability.
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| 3. |
- Liu, Longcheng, et al.
(author)
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Revisiting the Theory of Coagulation of Colloidal Dispersions : An Improved Expression for the Stability Ratio
- 2022
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In: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 38:3, s. 1131-1140
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Journal article (peer-reviewed)abstract
- The stability of a colloidal dispersion has long been expressed in terms of the stability ratio. Based on the available theories of coagulation of colloidal dispersions, a novel expression, complying with the classical definition, is developed for the stability ratio. It accounts for the contributions of both primary and secondary minimum coagulations to the overall rate of coagulations. In addition, it can also be regarded as the result of a combination of the kinetic theory of an ideal gas and the Smoluchowski theory with Fuchs' correction, considering the interaction between identical spherical particles and their surfaces immersed in a symmetrical electrolyte solution. The agreement with experimental data suggested that it is superior to the classical ones in describing the weak dependence of the stability ratio on the particle size and the valence of the counterion, by emphasizing the importance of the secondary minimum coagulation in dispersion stability and the complementation between the two modes of coagulation.
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| 4. |
- Liu, Zhenzhong, et al.
(author)
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Geochemical and S isotopic studies of pollutant evolution in groundwater after acid in situ leaching in a uranium mine area in Xinjiang
- 2023
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In: Nuclear engineering and technology. - : Elsevier BV. - 1738-5733 .- 2234-358X. ; 55:4, s. 1476-1484
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Journal article (peer-reviewed)abstract
- Laboratory experiments and point monitoring of reservoir sediments have proven that stable sulfate reduction (SSR) can lower the concentrations of toxic metals and sulfate in acidic groundwater for a long time. Here, we hypothesize that SSR occurred during in situ leaching after uranium mining, which can impact the fate of acid groundwater in an entire region. To test this, we applied a sulfur isotope fractionation method to analyze the mechanism for natural attenuation of contaminated groundwater produced by acid in situ leaching of uranium (Xinjiang, China). The results showed that delta S-34 increased over time after the cessation of uranium mining, and natural attenuation caused considerable, area-scale immobilization of sulfur corresponding to retention levels of 5.3%-48.3% while simultaneously decreasing the concentration of uranium. Isotopic evidence for SSR in the area, together with evidence for changes of pollutant concentrations, suggest that area-scale SSR is most likely also important at other acid mining sites for uranium, where retention of acid groundwater may be strengthened through natural attenuation. To recapitulate, the sulfur isotope fractionation method constitutes a relatively accurate tool for quantification of spatiotemporal trends for groundwater during migration and transformation resulting from acid in situ leaching of uranium in northern China.
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| 5. |
- Cao, Shan, et al.
(author)
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L-arginine metabolism inhibits arthritis and inflammatory bone loss
- 2024
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In: Annals of the Rheumatic Diseases. - : BMJ PUBLISHING GROUP. - 0003-4967 .- 1468-2060. ; 83, s. 72-87
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Journal article (peer-reviewed)abstract
- ObjectivesTo investigate the effect of the L-arginine metabolism on arthritis and inflammation-mediated bone loss.MethodsL-arginine was applied to three arthritis models (collagen-induced arthritis, serum-induced arthritis and human TNF transgenic mice). Inflammation was assessed clinically and histologically, while bone changes were quantified by mu CT and histomorphometry. In vitro, effects of L-arginine on osteoclast differentiation were analysed by RNA-seq and mass spectrometry (MS). Seahorse, Single Cell ENergetIc metabolism by profilIng Translation inHibition and transmission electron microscopy were used for detecting metabolic changes in osteoclasts. Moreover, arginine-associated metabolites were measured in the serum of rheumatoid arthritis (RA) and pre-RA patients.ResultsL-arginine inhibited arthritis and bone loss in all three models and directly blocked TNF alpha-induced murine and human osteoclastogenesis. RNA-seq and MS analyses indicated that L-arginine switched glycolysis to oxidative phosphorylation in inflammatory osteoclasts leading to increased ATP production, purine metabolism and elevated inosine and hypoxanthine levels. Adenosine deaminase inhibitors blocking inosine and hypoxanthine production abolished the inhibition of L-arginine on osteoclastogenesis in vitro and in vivo. Altered arginine levels were also found in RA and pre-RA patients.ConclusionOur study demonstrated that L-arginine ameliorates arthritis and bone erosion through metabolic reprogramming and perturbation of purine metabolism in osteoclasts.
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| 6. |
- Liu, Longcheng, et al.
(author)
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A new analytical solution of contaminant transport along a single fracture connected with porous matrix and its time domain random walk algorithm
- 2022
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In: Journal of Hydrology. - : Elsevier BV. - 0022-1694 .- 1879-2707. ; 610, s. 127828-
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Journal article (peer-reviewed)abstract
- In this work, a new solution is developed for the problem of contaminant transport in a single fracture-matrix system, where the first-order reaction rate constants are different in both fracture and matrix. It takes a form of convolution with three functions as a basis to consider different transport mechanisms separately. The statistical nature of the three functions, as well as the interpretation of the solution as a marginal probability distribution in the case of no first-order reactions, allows us to develop a simple Time Domain Random Walk (TDRW) algorithm to calculate the breakthrough curves at a given point of observation downstream the fracture. Compared with the existing versions of the TDRW algorithm, it is superior not only in the physical reasoning and statistical interpretations but also in its numerical implementations. In addition, the developed algorithm can not only be used to estimate the distribution profile of the contaminant concentration along the fracture but also the concentration within the matrix, since the analytical solution to contaminant concentration in the matrix also takes a convolution form of three functions. Also, the distribution profile of contaminant concentration within the matrix can readily be determined by the use of our TDRW algorithm. To validate the developed algorithm, three benchmark cases are considered for either nuclide or colloid transport through a fractured rock. The results show that TDRW algorithm is superior to the Gaussian quadrature solution, but similar to inverse Laplace transform solution, in computational expense when nearly identical results are obtained. However, the Monte Carlo nature of the TDRW algorithm implies that the accuracy of the computational result is related to the number of particles applied in the simulation, which might make the obtained results fluctuated.
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| 7. |
- Shang, Yuchen, et al.
(author)
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Ultrahard bulk amorphous carbon from collapsed fullerene
- 2021
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In: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 599:7886, s. 599-604
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Journal article (peer-reviewed)abstract
- Amorphous materials inherit short- and medium-range order from the corresponding crystal and thus preserve some of its properties while still exhibiting novel properties1,2. Due to its important applications in technology, amorphous carbon with sp2 or mixed sp2–sp3 hybridization has been explored and prepared3,4, but synthesis of bulk amorphous carbon with sp3 concentration close to 100% remains a challenge. Such materials inherit the short-/medium-range order of diamond and should also inherit its superior properties5. Here, we successfully synthesized millimetre-sized samples—with volumes 103–104 times as large as produced in earlier studies—of transparent, nearly pure sp3 amorphous carbon by heating fullerenes at pressures close to the cage collapse boundary. The material synthesized consists of many randomly oriented clusters with diamond-like short-/medium-range order and possesses the highest hardness (101.9 ± 2.3 GPa), elastic modulus (1,182 ± 40 GPa) and thermal conductivity (26.0 ± 1.3 W m−1 K−1) observed in any known amorphous material. It also exhibits optical bandgaps tunable from 1.85 eV to 2.79 eV. These discoveries contribute to our knowledge about advanced amorphous materials and the synthesis of bulk amorphous materials by high-pressure and high-temperature techniques and may enable new applications for amorphous solids.
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| 8. |
- Wu, Bingze, et al.
(author)
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Significant electron-phonon coupling in nanographene confined in single-walled carbon nanotubes due to the large amplitude of radial breathinglike vibrations
- 2024
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In: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 109:19
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Journal article (peer-reviewed)abstract
- One-dimensional (1D) van der Waals heterostructures (vdWHs) exhibit many properties, but many of these are difficult to understand because of their complicated structures and host-guest couplings that remain challenging to understand. Here, we observe a significant electron-phonon coupling (EPC) in 1D armchair graphene nanoribbons (AGNRs) confined in single-walled carbon nanotubes (SWNTs) via resonance Raman spectroscopy combined with theoretical calculation. A strong coupling between radial breathinglike mode (RBLM) phonons and the host nanotubes occurs due to the large vibration amplitude of RBLMs of the guest AGNRs. This results in unique deformation potential interactions in the heterostructure, contributing to the observed EPC enhancement. The EPC could be further modulated and strengthened by high pressure through tuning the RBLM-nanotube interactions. In this paper, we discover a mechanism governing the EPC in vdWHs and pave the way for manipulating the host-guest EPC for further control of the physical properties and potential device applications.
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| 9. |
- Yin, Xiu, et al.
(author)
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Doping of charge-transfer molecules in cocrystals for the design of materials with novel piezo-activated luminescence
- 2023
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In: Chemical Science. - : Royal Society of Chemistry. - 2041-6520 .- 2041-6539. ; 14:6, s. 1479-1484
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Journal article (peer-reviewed)abstract
- A novel piezo-activated luminescent material with wide range modulation of the luminescence wavelength and a giant intensity enhancement upon compression was prepared using a strategy of molecular doping. The doping of THT molecules into TCNB-perylene cocrystals results in the formation of a weak but pressure-enhanced emission center in the material at ambient pressure. Upon compression, the emissive band from the undoped component TCNB-perylene undergoes a normal red shift and emission quenching, while the weak emission center shows an anomalous blue shift from 615 nm to 574 nm and a giant luminescence enhancement up to 16 GPa. Further theoretical calculations show that doping by THT could modify intermolecular interactions, promote molecular deformation, and importantly, inject electrons into the host TCNB-perylene upon compression, which contributes to the novel piezochromic luminescence behavior. Based on this finding, we further propose a universal approach to design and regulate the piezo-activated luminescence of materials by using other similar dopants.
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| 10. |
- Zhai, Chunguang, et al.
(author)
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Molecular insertion regulates the donor-acceptor interactions in cocrystals for the design of piezochromic luminescent materials
- 2021
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In: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 12:1
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Journal article (peer-reviewed)abstract
- Developing a universal strategy to design piezochromic luminescent materials with desirable properties remains challenging. Here, we report that insertion of a non-emissive molecule into a donor (perylene) and acceptor (1,2,4,5-tetracyanobezene) binary cocrystal can realize fine manipulation of intermolecular interactions between perylene and 1,2,4,5-tetracyanobezene (TCNB) for desirable piezochromic luminescent properties. A continuous pressure-induced emission enhancement up to 3 GPa and a blue shift from 655 to 619 nm have been observed in perylene-TCNB cocrystals upon THF insertion, in contrast to the red-shifted and quenched emission observed when compressing perylene-TCNB cocrystals and other cocrystals reported earlier. By combining experiment with theory, it is further revealed that the inserted non-emissive THF forms blue-shifting hydrogen bonds with neighboring TCNB molecules and promote a conformation change of perylene molecules upon compression, causing the blue-shifted and enhanced emission. This strategy remains valid when inserting other molecules as non-emissive component into perylene-TCNB cocrystals for abnormal piezochromic luminescent behaviors.
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