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| 2. |
- Qu, Gang, et al.
(författare)
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Enhancing the Performance of the p-n Heterostructure Electrolyte for Solid Oxide Fuel Cells via A-Site-Deficiency Engineering
- 2023
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 15:42, s. 49154-49169
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Tidskriftsartikel (refereegranskat)abstract
- Semiconductor ionic electrolytes are attracting growing interest for developing low-temperature solid oxide fuel cells (LT-SOFCs). Our recent study has proposed a p-n heterostructure electrolyte based on perovskite oxide BaCo0.4Fe0.4Zr0.1Y0.1O3-δ (BCFZY) and ZnO, achieving promising fuel cell performance. Herein, to further improve the performance of the heterostructure electrolyte, an A-site-deficiency strategy is used to solely modify BCFZY for regulating the ionic conduction and catalytic activity of the heterostructure. Two new electrolytes, B0.9CFZY-ZnO and B0.8CFZY-ZnO, were developed and systematically studied. The results show that the two samples gain improved ionic conductivity and auxiliary catalytic activity after A-site deficiency as a result of the increment of the surface and interface oxygen vacancies. The single cells with B0.9CFZY-ZnO and B0.8CFZY-ZnO exhibit enhanced peak power outputs at 450-550 °C compared to the cell based on B1.0CFZY-ZnO (typically, 745 and 795 vs 542 mW cm-2 at 550 °C). Particular attention is paid to the impact of A-site deficiency on the interface energy band alignment between BxCFZY and ZnO, which suggests that the p-n heterojunction effect of BxCFZY-ZnO for charge carrier regulation can be tuned by A-site deficiency to enable high proton transport while avoiding fuel cell current leakage. This study thus confirms the feasibility of A-site-deficiency engineering to optimize the performance of the heterostructure electrolyte for developing LT-SOFCs.
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| 3. |
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| 4. |
- Wu, Jianlong, et al.
(författare)
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Study on Direct Reduction in Carbon-Bearing Pellets Using Biochar
- 2023
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Ingår i: Sustainability. - : MDPI AG. - 2071-1050. ; 15:24
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Tidskriftsartikel (refereegranskat)abstract
- As a renewable, carbon-neutral raw material, the application of biomass in steel production is conducive to reducing greenhouse gas emissions and achieving green and sustainable development in the steel industry. The heating and reduction process of a rotary hearth furnace was simulated under laboratory conditions to roast and reduce biochar carbon-bearing pellets with coke powder and anthracite carbon-bearing pellets as a comparison. This was conducted to investigate the impact of biochar as a reducing agent on the direct reduction in carbon-bearing pellets. Under various reduction temperatures, carbon/oxygen ratios, and reduction times, tests were conducted on the compressive strength and metallization rate of carbon-bearing pellets made using typical binder bentonite. Results show that with the increase in reduction temperature, the metallization rate of pellets increases, while the compressive strength initially decreases and then increases, reaching the lowest point at 900 degrees C and 1000 degrees C. When the ratio of carbon to oxygen is between 0.7 and 0.9 and the reduction time is between 15 and 25 min, carbon-bearing pellets meet the requirements of both the metallization rate and the strength, with the metallization rate above 80%. However, severe volume swelling and low strength were observed in biochar carbon-bearing pellets at 900 degrees C and 1000 degrees C, which negatively impacted multi-layered charging and heat transfer efficiency in the blast furnace. Therefore, a novel laboratory-prepared binder was introduced in the preparation process of biochar carbon-bearing pellets at an appropriate addition ratio of 5-8%. Without producing any swelling concerns, the inclusion of this binder considerably improved the compression strength and metallization rate of the pellets, enabling them to fulfill the standards for raw materials in the blast furnace.
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| 5. |
- Chen, Bin, et al.
(författare)
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Full-colour luminescent compounds based on anthracene and 2,2 '-dipyridylamine
- 2013
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Ingår i: Journal of Materials Chemistry C. - : Royal Society of Chemistry (RSC). - 2050-7526 .- 2050-7534. ; 1:44, s. 7409-7417
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Tidskriftsartikel (refereegranskat)abstract
- Starting from two simple units of anthracene and 2,2'-dipyridylamine, a series of new luminescent compounds 1-8 were designed and synthesized by a combined strategy of changing the connection mode between the two units, extending the conjugation size, and introducing an additional electron donor. Photophysical properties of 1-8 were investigated and discussed on the basis of solvatochromic behaviour, theoretical calculations, crystal structure, and optimized structures. Interestingly, the emission wavelengths of these compounds could be successfully tuned from violet to red both in solutions and the solid-state, and prominent positive solvatochromism was observed for the compounds with a D-p-A framework. Consider compound 7 as an example, it shows peaks at 526 nm and 627 nm in cyclohexane and DMSO, respectively. Meanwhile, the quantum yield was decreased from 0.80 in cyclohexane to 0.12 in DMSO. The introduction of bulky groups was demonstrated to be effective for suppressing the aggregation effect and thus improving the solid state emission quantum yield. These results indicate that the combined structure modulation strategy offers a powerful tool for tuning the emission behaviour. To demonstrate the possibility of practical applications, 2 was employed as the emitting material for the fabrication of deep-blue organic light-emitting diodes (OLEDs), which showed a maximum external quantum efficiency of 2.2%. The CIE coordinates of (0.15, 0.08) are indicative of excellent blue color purity.
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| 6. |
- Chen, Gang, et al.
(författare)
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Next-to-MHV Yang-Mills kinematic algebra
- 2021
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Ingår i: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; :10
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Tidskriftsartikel (refereegranskat)abstract
- Kinematic numerators of Yang-Mills scattering amplitudes possess a rich Lie algebraic structure that suggest the existence of a hidden infinite-dimensional kinematic algebra. Explicitly realizing such a kinematic algebra is a longstanding open problem that only has had partial success for simple helicity sectors. In past work, we introduced a framework using tensor currents and fusion rules to generate BCJ numerators of a special subsector of NMHV amplitudes in Yang-Mills theory. Here we enlarge the scope and explicitly realize a kinematic algebra for all NMHV amplitudes. Master numerators are obtained directly from the algebraic rules and through commutators and kinematic Jacobi identities other numerators can be generated. Inspecting the output of the algebra, we conjecture a closed-form expression for the master BCJ numerator up to any multiplicity. We also introduce a new method, based on group algebra of the permutation group, to solve for the generalized gauge freedom of BCJ numerators. It uses the recently introduced binary BCJ relations to provide a complete set of NMHV kinematic numerators that consist of pure gauge.
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| 7. |
- Chen, Gang, et al.
(författare)
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On the kinematic algebra for BCJ numerators beyond the MHV sector
- 2019
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Ingår i: Journal of High Energy Physics (JHEP). - : Springer. - 1126-6708 .- 1029-8479. ; :11
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Tidskriftsartikel (refereegranskat)abstract
- The duality between color and kinematics present in scattering amplitudes of Yang-Mills theory strongly suggests the existence of a hidden kinematic Lie algebra that controls the gauge theory. While associated BCJ numerators are known on closed forms to any multiplicity at tree level, the kinematic algebra has only been partially explored for the simplest of four-dimensional amplitudes: up to the MHV sector. In this paper we introduce a framework that allows us to characterize the algebra beyond the MHV sector. This allows us to both constrain some of the ambiguities of the kinematic algebra, and better control the generalized gauge freedom that is associated with the BCJ numerators. Specifically, in this paper, we work in dimension-agnostic notation and determine the kinematic algebra valid up to certain ? ((epsilon i .epsilon j )(2)) terms that in four dimensions compute the next-to-MHV sector involving two scalars. The kinematic algebra in this sector is simple, given that we introduce tensor currents that generalize standard Yang-Mills vector currents. These tensor currents control the generalized gauge freedom, allowing us to generate multiple different versions of BCJ numerators from the same kinematic algebra. The framework should generalize to other sectors in Yang-Mills theory.
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| 8. |
- Jiang, Jin-gang, et al.
(författare)
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Medical robotics
- 2015
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Ingår i: Advances in Mechanical Engineering. - : SAGE Publications. - 1687-8132 .- 1687-8140. ; 7:7
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 9. |
- Klevebro, Susanna, et al.
(författare)
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Risk of SARS-CoV-2 exposure among hospital healthcare workers in relation to patient contact and type of care
- 2021
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Ingår i: Scandinavian Journal of Public Health. - : SAGE Publications. - 1403-4948 .- 1651-1905. ; 49:7, s. 707-712
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Tidskriftsartikel (refereegranskat)abstract
- We aimed to assess prevalence of IgG antibodies to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and factors associated with seropositivity in a large cohort of healthcare workers (HCWs). Methods: From 11 May until 11 June 2020, 3981 HCWs at a large Swedish emergency care hospital provided serum samples and questionnaire data. Presence of IgG antibodies to SARS-CoV-2 was measured as an indicator of SARS-CoV-2 exposure. Results: The total seroprevalence was 18% and increased during the study period. Among the seropositive HCWs, 11% had been entirely asymptomatic. Participants who worked with COVID-19 patients had higher odds for seropositivity: adjusted odds ratio 1.96 (95% confidence intervals 1.59–2.42). HCWs from three of the departments managing COVID-19 patients had significantly higher seroprevalences, whereas the prevalence among HCWs from the intensive care unit (also managing COVID-19 patients) was significantly lower. Conclusions: HCWs in contact with SARS-CoV-2 infected patients had a variable, but on average higher, likelihood for SARS-CoV-2 infections.
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| 10. |
- Konig-Haagen, Andreas, et al.
(författare)
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Analysis of the discharging process of latent heat thermal energy storage units by means of normalized power parameters
- 2023
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Ingår i: Journal of Energy Storage. - : Elsevier BV. - 2352-152X .- 2352-1538. ; 72
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Tidskriftsartikel (refereegranskat)abstract
- Many efforts are being made to mitigate the main disadvantage of most phase change materials - their low thermal conductivities - in order to deliver latent heat energy storage systems (LHESS) with adequate perfor-mance. However, the effect of applied methods is difficult to compare as they are mostly tested for different storage types and sizes and/or different boundary and initial conditions, which hinders rapid progress in the optimization of these approaches. In this work, a previously developed method for comparing the performance of LHESS is applied to experimental results of different storage systems under different conditions and subsequently analyzed and further refined. The main idea of the method is to normalize the power with the volume and a reference temperature difference and compare its mean value plotted over the normalized mean capacity flow of the heat transfer fluid (HTF). This enables the presentation of the results in a compact and easily comparative way. Attention has to be paid when it comes to the choice of the reference temperature difference, the reference volume and the method for calculating the mean value. Two variants of calculating the mean value (time-weighted and energy-weighted) and two variants of reference temperatures for determining the temperature difference to the inlet temperature of the HTF (initial temperature and melting temperature) are applied and discussed in detail. While the method significantly increases the comparability of results, none of the options listed above are without drawbacks. Approaches are shown to reduce or eliminate these drawbacks in the future. The recommendation for comparing different LHESS under different conditions is to use the method described here and clearly state the chosen reference temperature, reference volume and method for calculating the mean value.
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