| 1. |
- Yang, Xiaoyong, et al.
(författare)
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Investigating the solution and diffusion properties of hydrogen in alpha-Uranium by first-principles calculations
- 2020
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Ingår i: Progress in nuclear energy (New series). - : PERGAMON-ELSEVIER SCIENCE LTD. - 0149-1970 .- 1878-4224. ; 122
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Tidskriftsartikel (refereegranskat)abstract
- The stability, solution and diffusion properties of an interstitial hydrogen atom in uranium metal have been firstly investigated by first-principles calculations. In energy, the octahedral site is more favorable for hydrogen to occupy than tetrahedra site with neglectable anisotropic perturbation. Besides, the effects of temperature on solution energy are quantified, which demonstrate the solution energy decreases fast with temperature. The calculated density of states and electronic charge re-distribution are analyzed. It is found the conductivity of metal uranium remains well after hydrogen occupied the interstitial position with lower concentration. The minimum migration pathways of interstitial hydrogen in uranium lattice are characterized by the climbing image nudged elastic band (CINEB) method. The obtained energy barriers are 0.239 eV, 0.298 eV and 0.313 eV with respect to O <-> T, O <-> O and T <-> T pathways with feeble structural deterioration. We believe our results for hydrogen diffusion in such a complex f -electron system not only provide en evidence for uranium corrosion but also supports the future experiments on measuring the hydriding rate and their interpretations.
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| 2. |
- Sai, Hanna, et al.
(författare)
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Observations of the very young Type Ia Supernova 2019np with early-excess emission
- 2022
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 514:3, s. 3541-3558
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Tidskriftsartikel (refereegranskat)abstract
- Early-time radiative signals from Type Ia supernovae (SNe Ia) can provide important constraints on the explosion mechanism and the progenitor system. We present observations and analysis of SN 2019np, a nearby SN Ia discovered within 1–2 days after the explosion. Follow-up observations were conducted in optical, ultraviolet, and near-infrared bands, covering the phases from ∼−16.7 d to ∼+ 367.8 d relative to its B-band peak luminosity. The photometric and spectral evolutions of SN 2019np resemble the average behaviour of normal SNe Ia. The absolute B-band peak magnitude and the post-peak decline rate are Mmax(B) = −19.52 ± 0.47 mag and Δm15(B) = 1.04 ± 0.04 mag, respectively. No Hydrogen line has been detected in the nebular-phase spectra of SN 2019np. Assuming that the 56Ni powering the light curve is centrally located, we find that the bolometric light curve of SN 2019np shows a flux excess up to 5.0 per cent in the early phase compared to the radiative diffusion model. Such an extra radiation perhaps suggests the presence of an additional energy source beyond the radioactive decay of central nickel. Comparing the observed colour evolution with that predicted by different models, such as interactions of SN ejecta with circumstellar matter (CSM)/companion star, a double-detonation explosion from a sub-Chandrasekhar mass white dwarf (WD) and surface 56Ni mixing, we propose that the nickel mixing is more favoured for SN 2019np.
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| 3. |
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| 4. |
- Luo, Shijian, et al.
(författare)
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RoamFab : A Design Tool for Reconfiguring Parameterized Mechanisms to 3D Models With Structural Optimization
- 2023
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Ingår i: International Journal of Human-Computer Interaction. - : Informa UK Limited. - 1044-7318 .- 1532-7590. ; 39:19, s. 3702-3716
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Tidskriftsartikel (refereegranskat)abstract
- Creating personalized 3D printing objects has become increasingly popular with the advance in end-user modeling tools and fabrication techniques. However, it remains challenging for novice makers to design and fabricate functional objects with mechanical motion such as linear or rotational. To empower users to add mechanical movements to their models for particular needs, we first investigate the commonly used 3D printable mechanisms and parameterize four mechanical primitives. We then provide a computational approach to reconfigure the mechanical primitives to user-provided 3D models, with an underlying structural optimization procedure according to a specified bending force. We further showcase a set of design examples and conduct a user study to demonstrate the potential of our approach in creating personalized functional artifacts.
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| 5. |
- Yang, Xiaoyong, et al.
(författare)
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An emerging Janus MoSeTe material for potential applications in optoelectronic devices
- 2019
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Ingår i: Journal of Materials Chemistry C. - : ROYAL SOC CHEMISTRY. - 2050-7526 .- 2050-7534. ; 7:39, s. 12312-12320
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Tidskriftsartikel (refereegranskat)abstract
- Motivated by the extraordinary physical and chemical properties of Janus transition-metal dichalcogenides (TMDs) due to the change of the crystal field originating from their asymmetry structures, the electronic and optical properties of the MoSeTe monolayer in 2H and 1T phases are systematically studied by first-principles calculations, and a detailed comparison with the parental MoSe2 and MoTe2 monolayer is made. It is found that 2H-MoSeTe exhibits a direct bandgap of 1.859 eV and an indirect band gap of 0.391 eV in the 1T phase, resulting in a different way to interact with sunlight. Besides, the obtained results show that the SOC has little effects on the band gaps. The calculated optical properties show a significant red shift from the MoSe2 to MoSeTe to MoTe2 monolayer. However, a blue shift is observed from the in-plane to out-of-plane direction. Moreover, both electron-electron and electron-hole correlation effects are considered for obtaining the optical spectra of systems by G(0)W(0) and G(0)W(0) + BSE approaches. Besides, the absorption coefficient value reaches up to 1 x 10(6) cm(-1) in both phases, implying the high efficiency in the utilization of solar energy for the MoSeTe monolayer. Additionally, the 1T-MoSeTe monolayer is a good hot mirror material in that its maximum reflectivity could reach up to 51% in the infrared region. Additionally, the average optical absorbance of the Janus MoSeTe monolayer in the visible light region is calculated to be about 2% and the corresponding average transmittance is around 80%. More importantly, the difference in the optical response for the two side surfaces is considered in our work due to the intrinsic asymmetric structure of Janus MoSeTe. These results not only predict the great potential application of Janus MoSeTe in optoelectronics-electronic devices, but may enable the discovery of new optical science and the realization of various light emissions, detection, modulation and manipulation functions of specific frequencies.
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| 6. |
- Yang, Xiaoyong, et al.
(författare)
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Interfacial aspect of ZnTe/In2Te3 heterostructures as an efficient catalyst for the hydrogen evolution reaction
- 2019
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 7:48, s. 27441-27449
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Tidskriftsartikel (refereegranskat)abstract
- In the class of two-dimensional (2D) materials, group III2-VI3 compounds have drawn intense attention due to its excellent surface properties. In this work, based on first-principles calculations, we have systematically investigated the structural, electronic, optical and photocatalytic properties of a ZnTe/In2Te3 heterostructure, along with its interfacial effects, to design an efficient photocatalyst. We have employed hydrogen adsorption free energy (Delta G(H*)) as a key parameter to demonstrate the enhancement in photocatalytic activity of ZnTe/In2Te3 compared to a pristine In2Te3 monolayer, which is further verified with the explicit water environment. The underlying mechanism is governed by the partial charge distributions of pristine In2Te3 and ZnTe/In2Te3 heterostructures. The presence of the ZnTe monolayer also altered the bandgap of the In2Te3 monolayer from an indirect gap of 1.238 eV to direct gaps of 0.298 eV and 0.181 eV in A- and B-type interfaces of the ZnTe/In2Te3 heterostructure, respectively. Calculated optical absorption spectra indicate that ZnTe/In2Te3 heterostructures possess better sunlight-harvesting capability compared to monolayer In2Te3 near the infrared and visible light regions, implying their potential as an excellent light-absorber. Our predictions provide new guidance for designing 2D III2-VI3 heterostructures and expand the applications of these materials in photovoltaics, photocatalysts, and other nanodevices in the future.
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| 7. |
- Yang, Xiaoyong, et al.
(författare)
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Sensing the polar molecules MH3 (M = N, P, or As) with a Janus NbTeSe monolayer
- 2020
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Ingår i: New Journal of Chemistry. - : Royal Society of Chemistry (RSC). - 1144-0546 .- 1369-9261. ; 44:19, s. 7932-7940
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Tidskriftsartikel (refereegranskat)abstract
- The unique intrinsic electric field and prominent physical and chemical properties of Janus TMDs have attracted extensive attention for device applications. In this work, the performance of a Janus NbTeSe monolayer as a gas sensor is systematically investigated towards (N, P, and As)H-3 molecules combining first-principles calculations and non-equilibrium Green's function formalism. The adsorption energies and configurations of the molecules on different sites of the Janus NbTeSe are determined. It is found AsH3 exhibits a stronger interaction with the substrate than NH3 and PH3, implying Janus NbTeSe is more sensitive towards AsH3. Besides, the visible difference of adsorption energies for the molecules on two sides shows the selectivity of the NbTeSe monolayer. Notably, the interaction between the molecules and the substrate becomes weaker under strain-driven, indicating the fast recovery and re-utilization of NbTeSe as a gas sensor device. Importantly, Janus NbTeSe exhibits a high anisotropic transport behavior; the modification of I-V responses correspondingly shows a surface-dependent trend. With higher gas sensitivity, surface selectivity and strain-driven desorption property, NbTeSe monolayer is proposed as a compelling and feasible candidate for gas sensing devices.
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| 8. |
- Yang, Xiaoyong, et al.
(författare)
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Unveiling the energetic and structural properties of Pu doped zircon through electrochemical equilibrium diagram from DFT plus U calculations
- 2020
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Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 539
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Tidskriftsartikel (refereegranskat)abstract
- Zircon (ZrSiO4) mineral is a sustainable and promising material to store of radioactive waste that has received extensive attention by material, geochemical and environmental scientists. Although the incorporation of actinide elements in zircon lattices has been experimentally studied, bare fundamental work are carried out to systemically assess the structural and chemical stabilities of Pu doped zircon. The primary aim to unveil the Pu immobilization mechanism and assess the stability of PuxZr1-xSiO4 is carried out by calculating the formation energies, electron and hole affinities, and electronic levels of Pu doped zircon based on density functional theory. Our results reveal under mu = mu(O-poor) condition Pu-Si(4+), Pu-Zr(1+) and Pu-Zr(0) are respectively energetically favorable to form with increasing the electronic chemical potential. Besides, Pu-Zr(4+) is energetically favorable in an n-type environment under all these three conditions (i.e., mu = mu(O-poor), mu = mu(Pu/Zr), mu = mu(Pu/Si)). In addition, Pu doping will induce local structural distortion. Intriguingly however, self-repairing the symmetry of [ZrO8] polyhedra is first observed via the structural distortion in Pu-Zr(4+) configuration, which in turn could enhance the structural stability of PuxZr1-xSiO4. Ab initio molecular dynamic simulations demonstrate the configurations with negative formation energies are thermal stable at 500 K. The charge density difference and charge transfer are investigated to describe the chemical bonding nature. It is demonstrated Pu(5f)-O(2p) hybridization is more profound for interstitial Pu. Moreover, the bonding character of surrounding Zr atoms along [010] direction is almost identical to the pristine one, while it is distinctly changed towards [100] and [001] directions, showing remarkable anisotropy of PuxZr1-xSiO4. Oppositely, the ionicity in Pu-O bond is mainly featured when Zr or Si sites are substituted by Pu atoms which becomes stronger with increasing the hole doping process. (C) 2020 Elsevier B.V. All rights reserved.
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| 9. |
- Yang, Xiao-Yong, et al.
(författare)
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Exploring Janus MoSSe monolayer as a workable media for SOF6 decompositions sensing based on DFT calculations
- 2021
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Ingår i: Computational materials science. - : Elsevier B.V.. - 0927-0256 .- 1879-0801. ; 186
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Tidskriftsartikel (refereegranskat)abstract
- In modern electric systems, partial discharge (PD) or local overheating happens inevitably, leading to the SF6 insulated switchgears decomposition into several types of gas molecules. Thus, online monitoring these decomposition gases is considered as a promising way to detect PD to timely alarm and guarantee the safety operation of power equipments. Here, we propose recently synthesized Janus monolayer MoSSe as a superior gas sensing material by investigating the adsorption behaviors of SF6 decompositions, including H2S, SO2, SOF2 and SO2F2 on Janus surfaces by first-principles calculations. The adsorption patten of SF6 decompositions on MoSSe monolayer is: SO2 > SO2F2 > H2S > SOF2, in which all the absorptions exhibit physisorption. Besides, the binding strengths of the molecules adsorbed on S-layer are weaker than these on Se-layer due to the presence of out-of-plane polarization in Janus monolayer. While the adsorption strengths can be slightly enhanced by intrinsic S/Se vacancies or strain-driven of MoSSe monolayer. Importantly, the adsorption intensity can be modulated effectively by the applied electric fields. Furthermore, the response and desorption time of gas molecules on MoSSe monolayer are evaluated. With high gas sensitivity and selectivity towards SF6 decompositions, Janus MoSSe monolayer is demonstrated to be a promising material to be used in gas-insulated switch-gear (GIS) and constructed ultrahigh sensitivity nanodevices.
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