| 1. |
- Ye, Yin, et al.
(author)
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Efficient and durable uranium extraction from uranium mine tailings seepage water via a photoelectrochemical method
- 2021
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In: iScience. - : Elsevier BV. - 2589-0042. ; 24:11
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Journal article (peer-reviewed)abstract
- Current photocatalytic uranium (U) extraction methods have intrinsic obstacles, such as the recombination of charge carriers, and the deactivation of catalysts by extracted U. Here we show that, by applying a bias potential on the photocatalyst, the photoelectrochemical (PEC) method can address these limitations. We demonstrate that, owing to efficient spatial charge-carriers separation driven by the applied bias, the PEC method enables efficient and durable U extraction. The effects of multiple operation conditions are investigated. The U extraction proceeds via single-step one-electron reduction, resulting in the formation of pentavalent U, which can facilitate future studies on this often-overlooked U species. In real seepage water the PEC method achieves an extraction capacity of 0.67 gU m(-3).h(-1) without deactivation for 156 h continuous operation, which is 17 times faster than the photocatalytic method. This work provides an alternative tool for U resource recovery and facilitates future studies on U(V) chemistry.
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| 2. |
- Ye, Yin, et al.
(author)
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Electrochemical removal and recovery of uranium: Effects of operation conditions, mechanisms, and implications
- 2022
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In: Journal of Hazardous Materials. - : Elsevier BV. - 1873-3336 .- 0304-3894. ; 432
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Journal article (peer-reviewed)abstract
- Removing and recovering uranium (U) from U-mining wastewater would be appealing, which simultaneously reduces the adverse environmental impact of U mining activities and mitigates the depletion of conventional U resources. In this study, we demonstrate the application of a constant-voltage electrochemical (CVE) method for the removal and recovery of U from U-mining wastewater, in an ambient atmosphere. The effects of operation conditions were elucidated in synthetic U-bearing water experiments, and the cell voltage and the ionic strength were found to play important roles in both the U extraction kinetics and the operation cost. The mechanistic studies show that, in synthetic U-bearing water, the CVE U extraction proceeds exclusively via a single-step one-electron reduction mechanism, where pentavalent U is the end product. In real U-mining wastewater, the interference of water matrices led to the disproportionation of the pentavalent U, resulting in the formation of tetravalent and hexavalent U in the extraction products. The U extraction efficacy of the CVE method was evaluated in real U-mining wastewater, and results show that the CVE U extraction method can be efficient with operation costs ranging from $0.55/kgU ~ $64.65/kgU, with varying cell voltages from 1.0 V to 4.0 V, implying its feasibility from the economic perspective.
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| 3. |
- Ye, Yin, et al.
(author)
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Removal and recovery of aqueous U(VI) by heterogeneous photocatalysis: Progress and challenges
- 2022
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In: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947. ; 450
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Research review (peer-reviewed)abstract
- With the rapidly expanding implementations of nuclear power technology, the contamination of the aquatic environment by uranium is a rising environmental problem. Photocatalytic reduction of hexavalent uranium (U(VI)) is a plausible solution to the aqueous uranium contamination, which has generated increasing research interest in the recent decade. Therefore, a systematic assessment highlighting the important direction for future studies is in need. We herein present a critical review to address the following two aspects: (1) the progress and current understandings of photocatalytic U(VI) removal technology, including various applied catalysts, current understanding of the kinetics and mechanisms, the effects of key operation parameters, and the effects of co-existing water constituents; (2) key knowledge gaps that need future research efforts in this field.
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| 4. |
- Zhang, Zhifei, et al.
(author)
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An encrusting kleptoparasite-host interaction from the early Cambrian
- 2020
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In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 11
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Journal article (peer-reviewed)abstract
- Parasite–host systems are pervasive in nature but are extremely difficult to convincingly identify in the fossil record. Here we report quantitative evidence of parasitism in the form of a unique, enduring life association between tube-dwelling organisms encrusted to densely clustered shells of a monospecific organophosphatic brachiopod assemblage from the lower Cambrian (Stage 4) of South China. Brachiopods with encrusting tubes have decreased biomass (indicating reduced fitness) compared to individuals without tubes. The encrusting tubes orient tightly in vectors matching the laminar feeding currents of the host, suggesting kleptoparasitism. With no convincing parasite–host interactions known from the Ediacaran, this widespread sessile association reveals intimate parasite–host animal systems arose in early Cambrian benthic communities and their emergence may have played a key role in driving the evolutionary and ecological innovations associated with the Cambrian radiation.
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| 5. |
- Zhang, Zhiliang, et al.
(author)
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Go large or go conical : allometric trajectory of an early Cambrian acrotretide brachiopod
- 2021
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In: Palaeontology. - : John Wiley & Sons. - 0031-0239 .- 1475-4983. ; 64:5, s. 727-741
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Journal article (peer-reviewed)abstract
- Acrotretides are extinct micromorphic brachiopods that exhibited considerable morphological variation during their rapid evolution in the early Palaeozoic. The plano-conical shells of acrotretides are distinct in comparison to other brachiopod groups and despite their diversity and abundance in early Palaeozoic communities, their origins, early evolution, life history and phylogeny are poorly understood. Here, we employ advanced geometric morphometrics to quantitatively investigate ontogenetic variation and allometry in the ventral valve of the oldest known acrotretide species from the early Cambrian of South China. Our results identify substantial shape variation for Eohadrotreta zhenbaensis, along with a parabolic morphological trajectory through ontogeny, demonstrating a remarkable reversal to PC1 values equivalent to those obtained for juveniles, during later ontogenetic stages. The evolutionary novel body plan (diminutive and plano-conical) of Acrotretida was established gradually during two phases of allometry, formed initially during the final stage of the Cambrian evolutionary radiation from an ancestral low, equivalved lingulide body plan. The development of a conical shaped valve seems to have resulted in an overall smaller body size, when compared with non-conical forms. The heterochronic processes responsible for generating these ontogenetic modifications at different allometric phases may have facilitated the evolutionary diversification of acrotretide brachiopods during the early Palaeozoic.
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| 6. |
- Zhang, Zhiliang, et al.
(author)
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The oldest Cambrian trilobite - brachiopod association in South China
- 2021
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In: Gondwana Research. - : Elsevier. - 1342-937X .- 1878-0571. ; 89, s. 147-167
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Journal article (peer-reviewed)abstract
- Limestones of the Xihaoping Member of the Dengying Formation in the Xiaoyangba section, South China, yield the oldest known Cambrian brachiopod-trilobite association. In this member, the trilobite Parabadiella cf. huoi co-occurs with the new brachiopod species Eoobolus incipiens sp. nov. The association provides potential for correlation of lower Cambrian successions and gives novel insights into the origin, palaeobiogeographic distribution and early evolution of linguliform brachiopods. Parabadiella occurs in shallow marine clastic and carbonate rocks in South China, demonstrating a broad distribution for this taxon. The new discovery indicates an early Chiungchussuan age (Parabadiella trilobite Zone, Cambrian Age 3) for the longstanding problematic Xihaoping Member. Furthermore, this earliest Parabadiella-Eoobolus association helps to establish close links with the oldest knowntrilobite-brachiopod assemblage from the upper Micrina etheridgei Zone (Parabadiella huoi trilobite Zone) in Australia. Eoobolus incipiens represents one of the earliest known linguliform brachiopods, with a distinctive mixture of characters shared with both problematic tommotiids, as well as paterinide, lingulide and acrotretide brachiopods, indicating that these features may be plesiomorphic for the Linguliformea. An age-constrained dispersal mode for early lingulate brachiopods is proposed, indicating that the Subphylum Linguliformea may have originated in East Gondwana and South China during Cambrian Age 3, and only subsequently dispersed to other major Cambrian palaeocontinents (e.g. Siberia, Laurentia, Antarctica, Baltica, Avalonia, West Gondwana, North China) during the late stage of the Cambrian evolutionary radiation of animals. (C) 2020 The Author(s). Published by Elsevier B.V. on behalf of International Association for Gondwana Research.
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| 7. |
- Chen, Jun, et al.
(author)
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A self-healing elastomer based on an intrinsic non-covalent cross-linking mechanism
- 2019
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In: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488. ; 7:25, s. 15207-15214
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Journal article (peer-reviewed)abstract
- Synthesis and comprehensive examination of a polyurethane (urea) elastomer that self-heals based on intrinsic dynamic non-covalent bonds (van der Waals and hydrogen) are reported. The dynamic non-covalent bonds include hydrogen bonds and van der Waals forces. The difference in the previous approach in which hydrogen bond self-healing materials introduced dense quadruple hydrogen bonds at the ends or branched chains poly(propylene carbonate) (PPC) diol was used as the soft segment of the polyurethane (urea) material, and strong van der Waals forces were provided by the large number of carbonyl groups in its main chain; hydrogen bonds were formed by urethane bonds, urea bonds, and the carbonyl groups on PPC. The mechanical properties and healing efficiency of the self-healing polyurethane (urea) elastomer were studied. In situtemperature-dependent infrared and low-field nuclear magnetic resonance (LNMR) measurements were combined with molecular dynamics simulations to investigate the self-healing mechanisms. The results of the studies on the self-healing polyurethane demonstrate that the dynamic cross-linking between hydrogen bonds and van der Waals forces is the basic driving force for the self-healing ability of the material, and temperature is the key factor that affects hydrogen bonding and van der Waals forces. The effect of crystallization on the self-healing ability of the material was also studied. The molecular dynamics simulation results also demonstrate interplay between van der Waals forces and hydrogen bonds at different temperatures.
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| 8. |
- Chen, Tianshi, et al.
(author)
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Impulse Response Estimation with Binary Measurements : A Regularized FIR Model
- 2012
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In: Proceedings of the 16th IFAC Symposium on System Identification. - 9783902823069 ; , s. 113-118
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Conference paper (peer-reviewed)abstract
- FIR (finite impulse response) model is widely used in tackling the problem of the impulse response estimation with quantized measurements. Its use is, however, limited, in the case when a high order FIR model is required to capture a slowly decaying impulse response. This is because the high variance for high order FIR models would override the low bias and thus lead to large MSE (mean square error). In this contribution, we apply the recently introduced regularized FIR model approach to the problem of the impulse response estimation with binary measurements. We show by Monte Carlo simulations that the proposed approach can yield both better accuracy and better robustness than a recently introduced FIR model based approach.
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| 9. |
- Chen, Yanlong, et al.
(author)
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Middle Triassic conodont assemblages from the Germanic Basin: implications for multi-element taxonomy and biogeography
- 2018
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In: Journal of Systematic Palaeontology. - : Informa UK Limited. - 1477-2019 .- 1478-0941. ; , s. 1-19
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Journal article (peer-reviewed)abstract
- Conodonts have been a key tool for biostratigraphical, evolutionary and palaeobiogeographical studies, and the GermanicBasin has been one of the most important regions for these studies. However, few modern studies provide systematic data onthe mainly endemic conodonts of the Middle Triassic Germanic Basin. Here we document conodonts from two sections inGermany, one Bithynian in age and the other late Anisian to early Ladinian in age. The two sections captured two episodesof marine fauna invasion in the Germanic epicontinental basin during the Middle Triassic. The conodont Neogondolellamombergensis, elsewhere reported as appearing globally, is reviewed and revised, confirming previous suggestions that thisspecies only occurs in the Germanic Basin. Apparatuses of Neogondolella haslachensis and Nicoraella germanica from theGermanic Basin are proposed. It was generally expected that S and M elements within clades have a very high morphologicalstability compared to P elements. However, the apparatus of Nicoraella germanica differs significantly from that of southChina, indicating that the morphology of S elements within a genus can be unstable, and thus promotes our understanding ofconodont evolution. The rarely documented genus Gondolatus, which was suggested as representing pathological specimens,is confirmed as a valid genus in the Germanic Basin. Our data suggest that endemic conodonts evolved twice, not only in theUpper Muschelkalk Subgroup, but also in the Lower Muschelkalk Subgroup.
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| 10. |
- Chen, Yanlong, et al.
(author)
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Quantitative stratigraphic correlation of Tethyan conodonts across the Smithian-Spathian (Early Triassic) extinction event
- 2019
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In: Earth-Science Reviews. - : Elsevier BV. - 0012-8252. ; 195, s. 37-51
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Research review (peer-reviewed)abstract
- Three small-scale extinctions occurred in the Early Triassic with one of them recognized close to the Smithian-Spathian boundary. In the last two decades, the end-Permian mass extinction as well as the subsequent recovery have been intensively studied throughout the Tethys region, but correlations within the Lower Triassic are difficult due to conodonts endemism. Here we use paleontological and geochemical methods to document a high-resolution biostratigraphy of the Smithian-Spathian boundary interval from two sections of Oman. In combination with previously published data from both South-Central Europe and South China, a quantitative stratigraphic correlation has been achieved with 7 conodont UA Zones recognized using the unitary association method. Based on conodonts and carbonate carbon isotope data, the Smithian-Spathian boundary is identified in the interval from UAZ4 to UAZ5 close to the last occurrence of Nv. pingdingshanensis in Oman and South China, and within the range of P. inclinata, Ns. planus, Pl. regularis, and Pl. corniger in South-Central Europe. UAZ7 fauna displays a clear diachronism as it starts from South China, arrives a bit later in Oman and even later in western Tethys. Foliella gardenae and Icriospathodus zaksi are reported from Oman for the first time and thus expand the geographical distribution of these rarely reported species.
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