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| 2. |
- Guo, Han, et al.
(författare)
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Transition metal-catalysed molecular n-doping of organic semiconductors
- 2021
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Ingår i: Nature. - London, United Kingdom : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 599:7883, s. 67-73
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Tidskriftsartikel (refereegranskat)abstract
- Electron doping of organic semiconductors is typically inefficient, but here a precursor molecular dopant is used to deliver higher n-doping efficiency in a much shorter doping time. Chemical doping is a key process for investigating charge transport in organic semiconductors and improving certain (opto)electronic devices(1-9). N(electron)-doping is fundamentally more challenging than p(hole)-doping and typically achieves a very low doping efficiency (eta) of less than 10%(1,10). An efficient molecular n-dopant should simultaneously exhibit a high reducing power and air stability for broad applicability(1,5,6,9,11), which is very challenging. Here we show a general concept of catalysed n-doping of organic semiconductors using air-stable precursor-type molecular dopants. Incorporation of a transition metal (for example, Pt, Au, Pd) as vapour-deposited nanoparticles or solution-processable organometallic complexes (for example, Pd-2(dba)(3)) catalyses the reaction, as assessed by experimental and theoretical evidence, enabling greatly increased eta in a much shorter doping time and high electrical conductivities (above 100 S cm(-1); ref. (12)). This methodology has technological implications for realizing improved semiconductor devices and offers a broad exploration space of ternary systems comprising catalysts, molecular dopants and semiconductors, thus opening new opportunities in n-doping research and applications(12, 13).
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| 3. |
- Yang, Weijia, 1989-, et al.
(författare)
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Experimental investigation of theoretical stability regions for ultra-low frequency oscillations of hydropower generating systems
- 2019
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Ingår i: Energy. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0360-5442 .- 1873-6785. ; 186
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Tidskriftsartikel (refereegranskat)abstract
- With the increasing momentum towards flexible power systems based on renewables, the role of hydropower has great importance, especially for providing balancing power. In this paper, a fundamental study on the operating stability of hydropower generating systems is conducted to reveal the practical characteristics for the newly emergent issue of ultra-low frequency oscillations. A unique study methodology is adapted by combing the theoretical analysis and the physical model experiment. In this paper, first, the set-up of the integral experiment platform for the transient processes of the pumped storage plants is presented. Second, a mathematical model of hydropower generating systems is built, and the theoretical stability analysis is conducted based on the Routh-Hurwitz criterion and the stability margin region. The model experiments related to the frequency stability of hydropower generating systems were conducted with reference to the stability region from theoretical analysis. The results demonstrate the sustained ultra-low frequency oscillations and frequency instability of hydropower units in experiments for the first time. Attenuation characteristics of the oscillations are theoretically derived based on the stability margin region, and then quantitatively identified by experiments. The experiment accorded with theoretical stability region within a reasonable tolerance that corresponded to the +/- 0.1 stability margin. (C) 2019 Elsevier Ltd. All rights reserved.
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| 4. |
- Duan, Yumin, et al.
(författare)
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Insight to bacteria community response of organic management in apple orchard-bagasse fertilizer combined with biochar
- 2022
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Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 286
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Tidskriftsartikel (refereegranskat)abstract
- Based on the sustainable development practice-zero growth in chemical fertilizer application, this article used bagasse organic fertilizer and rice husk derived biochar to investigate the response of soil bacterial community in apple orchard. Aimed at realize the soil quality improvement and biomass resource recovery to contribute agricultural and environmental sustainability. The co-trophic Proteobacteria was predominant in all the treatments (29–36 %) and enriched in non-nitrifying Alphaproteobacteria (9–11 %) and ammonia oxidant Betaproteobacteria (8–10 %), especially richest in bagasse fertilizer combine biochar treated soil. In addition, bacterial community variation was assessed by alpha and beta diversity, four treatments dispersed distribution and richer abundance observed in combined apply bagasse fertilizer and biochar treatment (3909.22 observed-species) than single application (3729.88 and 3646.58 observed-species). Biochar as microbial carrier combined organic fertilizer were established synergistic interaction and favorable to organic matter availability during sustainable agriculture. Finally, integrated biochar-bagasse fertilizer was richer than single organic or biochar fertilization in improving soil bacterial diversity, notably by promoting the metabolism of copiotrophic bacteria, nutrient cycling, plant growth and disease inhibit-related bacteria.
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| 5. |
- Fan, Zhiwen, et al.
(författare)
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Porous Ionic Network/CNT Composite Separator as a Polysulfide Snaring Shield for High Performance Lithium–Sulfur Battery
- 2023
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Ingår i: Macromolecular rapid communications. - 1022-1336 .- 1521-3927. ; 44:24
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Tidskriftsartikel (refereegranskat)abstract
- Lithium–sulfur (Li–S) battery features a high theoretical energy density, but the shuttle of soluble polysulfides between the two electrodes often results in a rapid capacity decay. Herein, a straightforward electrostatic adsorption strategy based on a cross-linked polyimidazolium separator as a snaring shield of polysulfides is reported, which suppresses the undesirable migration of polysulfides to the anode. The porous ionic network (PIN)-modified carbon nanotubes (CNTs) are successfully prepared and coated onto a commercial porous polypropylene membrane in a vacuum-filtration step. The favorable affinity of the imidazolium ring toward polysulfide via the polar interaction and the electrostatic effect of ions mitigates the undesirable shuttle of polysulfides in the electrolyte, improving the Li─S battery in terms of rate performance and cycling life. Compared to the reference PIN-free CNT-coated separator, the PIN/CNT-coated one has an increased initial capacity of 1.3 folds (up to 1394.8 mAh g−1 for PIN/CNT/PP-3) at 0.1 C.
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| 6. |
- Han, Delong, et al.
(författare)
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Analysis of Raman scattering from inclined GeSn/Ge dual-nanowire heterostructure on Ge(1 1 1) substrate
- 2019
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332. ; 463, s. 581-586
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, the Raman spectra of GeSn/Ge dual-nanowire heterostructure grown on Ge(1 1 1) substrate are systematically analyzed within the framework of anisotropic elasticity and lattice dynamical theory. Based on the experimental samples grown by molecular beam epitaxy, the partially covered dual nanowires standing along 〈1 1 0〉 direction are modeled and the heterostructure presents effective elastic strain relaxation due to the free surfaces. The simulations show that the Raman shift of GeSn nanowire is mainly affected by the Sn content while the influences of strain become less important with the increase of thickness ratio. For Ge nanowire, the peak of Raman spectrum merely moves with Sn content, but the spectrum possesses asymmetric broadening induced by the non-uniform strain distribution. The red-shift and intensity reduction of the total Raman spectrum of dual nanowires are observed when the Sn content increases. Moreover, an analytic fitting expression for Raman peak position is obtained based on the numerical results and is expected to serve as a reference to estimate the Sn content in GeSn/Ge dual-nanowire heterostructure.
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| 7. |
- Huang-Link, YuMin, 1962-, et al.
(författare)
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Optical coherence tomography represents a sensitive and reliable tool for routine monitoring of idiopathic intracranial hypertension with and without papilledema
- 2019
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Ingår i: European Journal of Neurology. - : WILEY. - 1351-5101 .- 1468-1331. ; 26:5, s. 808-
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Tidskriftsartikel (refereegranskat)abstract
- Background and purpose We previously reported that certain optical coherence tomography (OCT) measures were sensitive and reliable in identifying idiopathic intracranial hypertension (IIH). This prospective study aimed to define OCT measures that allow differentiation of IIH with and without papilledema, thereby helping clinical decision-making. Methods Eight patients with IIH with papilledema, nine without papilledema and 19 with other neurological diseases were included. OCT measures were obtained before lumbar puncture and within 2 h, 1, 3 and 6 months after lumbar puncture with cerebrospinal fluid (CSF) removal. Results All patients with papilledema had increased retinal nerve fiber layer (RNFL) thickness and elevated CSF pressure. All patients without papilledema had normal RNFL but elevated CSF pressure. After CSF removal, reduced RNFL thickness was registered in all eight patients with IIH with papilledema. No significant change in RNFL thickness after CSF removal was observed in IIH without papilledema or in patients with other neurological diseases, although reduced CSF pressure was documented. RNFL thickness tended to be normal in patients with IIH with papilledema at 3-6 months after CSF removal. All patients with IIH showed increased rim area and rim thickness, but reduced optic cup volume regardless of RNFL thickness or papilledema. Conclusions Retinal nerve fiber layer thickness is sensitive for monitoring acute IIH and evaluating treatment effect. Increased rim area and rim thickness and decreased optic cup volume are reliable parameters that indicate persistently increased CSF pressure and risk of relapse. OCT measures are sensitive and reliable for diagnosing subtle IIH even in the absence of papilledema.
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| 8. |
- Huang-Link, YuMin, 1962-, et al.
(författare)
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Optical Coherence Tomography to Monitor Rebound Intracranial Hypertension with Increased Papilledema after Lumbar Puncture
- 2021
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Ingår i: NEUROSCI. - : MDPI. - 2673-4087. ; 2:4, s. 334-338
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Tidskriftsartikel (refereegranskat)abstract
- Objective: We report that lumbar puncture (LP) with removal of cerebrospinal fluid (CSF) induced rebound intracranial hypertension with increased papilledema as monitored by optical coherence tomography (OCT). Background: Severe papilledema causes visual field loss and central vision damage if untreated. Fundoscopy is a key to diagnose papilledema, but is not sensitive enough to monitor therapeutic effects. Methods: OCT was applied to follow a 24-year-old woman with headache, visual dysfunction, severe bilateral papilledema, and elevated CSF opening pressure. She was first treated with serial LP, which led to symptom deterioration, increased CSF pressure, and increased the retinal nerve fiber layer (RNFL) thickness. She was then successfully treated with acetazolamide and furosemide. Results: OCT showed reduction of RNFL thickness directly after LP with CSF removal, accompanied with reduced CSF pressure. Increased RNFL thickness accompanied with worsened headache, visual dysfunction, and increased CSF pressure was observed on the next day after LP. Less than 24 h after start of medication, the symptoms had reversed and RNFL thickness was reduced. The patient was symptom-free 2 weeks after starting on medical treatment. Papilledema had vanished on fundoscopy 6 weeks after the therapy, and RNFL thickness was normalized at 3 months of follow-up. Conclusion: This case provides evidence that OCT is an objective and sensitive tool to monitor papilledema and its response to therapy, and thereby important to help in correct clinical decision-making.
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| 9. |
- Huang, Zheng, et al.
(författare)
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Constructing type-II CuInSe2/CuInS2 core/shell quantum dots for high-performance photoelectrochemical cells
- 2024
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Ingår i: SCIENCE CHINA Materials. - 2095-8226. ; 67:1, s. 134-142
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Tidskriftsartikel (refereegranskat)abstract
- CuInSe2 (CISe) quantum dots (QDs) have shown promising applications in photoelectrochemical (PEC) cells due to their nontoxicity, high extinction coefficient, and wide optical absorption range; however, their low PEC performance prevents their applications due to insufficient charge carrier separation and severe charge recombination. Herein, CISe/CuInS2 (CISe/CIS) core/shell structured QDs are designed and constructed to promote charge separation and diminish interface defects. Afterward, the copper vacancy (VCu) state of CISe/CIS QDs is enriched by modulating the precursor molar ratios of In/Cu. Therefore, the radiative recombination of the conduction band edge electrons with the VCu localized holes becomes dominant and prolongs the carrier lifetime compared with intrinsic band-to-band recombination, thus promoting charge separation. Consequently, the VCu-rich CISe/CIS QD-based photoanode shows a high photocurrent density of 8.0 mA cm−2, which is one of the highest values reported for CISe QD-based PEC cells. This work provides an effective approach for promoting charge carrier separation and transfer through surface or intrinsic defect mediation for PEC applications of I–III–VI semiconductor nanocrystals.
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| 10. |
- Jianfeng, Lin, 1994, et al.
(författare)
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Hydrodynamic performance of a rim-driven thruster improved with gap geometry adjustment
- 2023
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Ingår i: Engineering Applications of Computational Fluid Mechanics. - : Informa UK Limited. - 1994-2060 .- 1997-003X. ; 17:1
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Tidskriftsartikel (refereegranskat)abstract
- The hubless rim-driven thruster (RDT) has become increasingly interesting for ship propulsion. Gap flow has been proven as the main feature of RDT that cannot be simply neglected. In this study, based on a classical hubless RDT, the effects of the gap geometry are studied by adjusting its axial passage length, and inlet and outlet oblique angles. The hydrodynamic characteristics of the RDT were simulated with OpenFOAM based on the k – ω shear stress transport turbulence model. Due to the pressure increase after the main flow passes through the rotating blades, the flow inside gap is driven upstream, which is opposite to the main flow direction. It is found that the hydrodynamic efficiency is increased as the gap axial passage length is shortened, which is realized by increasing the oblique angle with the fixed inlet and outlet positions. Moving the inlet and outlet to further downstream and upstream positions has negligible effects on the hydrodynamic efficiency and leads to recirculating flow within the gap near its inlet. These findings shed light on the design of the gap geometry to improve the RDT hydrodynamic performance.
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