| 1. |
- Cheng, Chunyan, et al.
(författare)
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Near-Unity Quantum Yield ZnSeTe Quantum Dots Enabled by Controlling Shell Growth for Efficient Deep-Blue Light-Emitting Diodes
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Ingår i: Advanced Functional Materials. - 1616-301X.
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Tidskriftsartikel (refereegranskat)abstract
- Core–shell structural ZnSeTe/ZnSe/ZnS quantum dots (QDs) have attracted great attention for advanced illumination and displays because of their environmentally friendly composition, but still suffering from poor photoluminescence (PL) and electroluminescence (EL) performance due to severe non-radiative charge recombination. Herein, a stepwise injection shell growth process to manipulate the monomer concentration and ensure adequate growth interval is devised, which enables the controllable uniform epitaxial growth of ZnSe and ZnS shells on the ZnSeTe core, thus relieving the lattice distortion and defects to greatly suppress the non-radiative charge recombination. The ZnSeTe/ZnSe/ZnS QDs presented deep-blue emission at 448 nm with narrow full width at half maximum (FWHM, 23 nm), and near-unity PL quantum yield (PLQY, ≈100%) The light-emitting diodes (LEDs) based on the QDs exhibited a high external quantum efficiency (EQE) of 10.9%, a maximum brightness of 10240 cd cm−2, and a high current efficiency of 7.9 cd A−1, demonstrating a good performance for deep blue QDs LEDs (QLEDs) This shell growth strategy will be an effective approach to achieving efficient QDs and QLEDs.
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| 2. |
- Feng, Hongliang, et al.
(författare)
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Association between accelerometer-measured amplitude of rest-activity rhythm and future health risk : a prospective cohort study of the UK Biobank
- 2023
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Ingår i: The Lancet Healthy Longevity. - 2666-7568. ; 4:5, s. e200-e210
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The health effects of rest-activity rhythm are of major interest to public health, but its associations with health outcomes remain elusive. We aimed to examine the associations between accelerometer-measured rest-activity rhythm amplitude and health risks among the general UK population.METHODS: We did a prospective cohort analysis of UK Biobank participants aged 43-79 years with valid wrist-worn accelerometer data. Low rest-activity rhythm amplitude was defined as the first quintile of relative amplitude; all other quintiles were classified as high rest-activity rhythm amplitude. Outcomes of interest were defined using International Classification of Diseases 10th Revision codes and consisted of incident cancer and cardiovascular, infectious, respiratory, and digestive diseases, and all-cause and disease-specific (cardiovascular, cancer, and respiratory) mortality. Participants with a current diagnosis of any outcome of interest were excluded. We assessed the associations between decreased rest-activity rhythm amplitude and outcomes using Cox proportional hazards models.FINDINGS: Between June 1, 2013, and Dec 23, 2015, 103 682 participants with available raw accelerometer data were enrolled. 92 614 participants (52 219 [56·4%] women and 40 395 [42·6%] men) with a median age of 64 years (IQR 56-69) were recruited. Median follow-up was 6·4 years (IQR 5·8-6·9). Decreased rest-activity rhythm amplitude was significantly associated with increased incidence of cardiovascular diseases (adjusted hazard ratio 1·11 [95% CI 1·05-1·16]), cancer (1·08 [1·01-1·16]), infectious diseases (1·31 [1·22-1·41]), respiratory diseases (1·26 [1·19-1·34]), and digestive diseases (1·08 [1·03-1·14]), as well as all-cause mortality (1·54 [1·40-1·70]) and disease-specific mortality (1·73 [1·34-2·22] for cardiovascular diseases, 1·32 [1·13-1·55] for cancer, and 1·62 [1·25-2·09] for respiratory diseases). Most of these associations were not modified by age older than 65 years or sex. Among 16 accelerometer-measured rest-activity parameters, low rest-activity rhythm amplitude had the strongest or second- strongest associations with nine health outcomes.INTERPRETATION: Our results suggest that low rest-activity rhythm amplitude might contribute to major health outcomes and provide further evidence to promote risk-modifying strategies associated with rest-activity rhythm to improve health and longevity.
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| 3. |
- Feng, Hongliang, et al.
(författare)
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Associations of timing of physical activity with all-cause and cause-specific mortality in a prospective cohort study
- 2023
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Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- There is a growing interest in the role of timing of daily behaviors in improving health. However, little is known about the optimal timing of physical activity to maximize health benefits. We perform a cohort study of 92,139 UK Biobank participants with valid accelerometer data and all-cause and cause-specific mortality outcomes, comprising over 7 years of median follow-up (638,825 person-years). Moderate-to-vigorous intensity physical activity (MVPA) at any time of day is associated with lower risks for all-cause, cardiovascular disease, and cancer mortality. In addition, compared with morning group (>50% of daily MVPA during 05:00-11:00), midday-afternoon (11:00-17:00) and mixed MVPA timing groups, but not evening group (17:00-24:00), have lower risks of all-cause and cardiovascular disease mortality. These protective associations are more pronounced among the elderly, males, less physically active participants, or those with preexisting cardiovascular diseases. Here, we show that MVPA timing may have the potential to improve public health.
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| 4. |
- Tang, Binbin, et al.
(författare)
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Magnetic depression and electron transport in an ion-scale flux rope associated with Kelvin-Helmholtz waves
- 2018
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Ingår i: Annales Geophysicae. - : COPERNICUS GESELLSCHAFT MBH. - 0992-7689 .- 1432-0576. ; 36:3, s. 879-889
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Tidskriftsartikel (refereegranskat)abstract
- We report an ion-scale magnetic flux rope (the size of the flux rope is similar to 8.5 ion inertial lengths) at the trailing edge of Kelvin-Helmholtz (KH) waves observed by the Magnetospheric Multiscale (MMS) mission on 27 September 2016, which is likely generated by multiple X-line reconnection. The currents of this flux rope are highly filamentary: in the central flux rope, the current flows are mainly parallel to the magnetic field, supporting a local magnetic field increase at about 7 nT, while at the edges the current filaments are predominantly along the antiparallel direction, which induce an opposing field that causes a significant magnetic depression along the axis direction (> 20 nT), meaning the overall magnetic field of this flux rope is depressed compared to the ambient magnetic field. Thus, this flux rope, accompanied by the plasma thermal pressure enhancement in the center, is referred to as a crater type. Intense lower hybrid drift waves (LHDWs) are found at the magnetospheric edge of the flux rope, and the wave potential is estimated to be similar to 17% of the electron temperature. Though LHDWs may be stabilized by the mechanism of electron resonance broadening, these waves could still effectively enable diffusive electron transports in the cross-field direction, corresponding to a local density dip. This indicates LHDWs could play important roles in the evolution of crater flux ropes.
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| 5. |
- Tao, Sun, et al.
(författare)
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Elasto-dynamicoptimization of a 5-DoF parallel kinematic machine considering parameteruncertainty
- 2019
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Ingår i: IEEE/ASME transactions on mechatronics. - : IEEE. - 1083-4435 .- 1941-014X. ; :1, s. 315-325
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Tidskriftsartikel (refereegranskat)abstract
- Geometric errors, vibration, and elastic deformation are the main causes for inaccuracy of parallel kinematic machines (PKMs). Instead of tackling these inaccuracies after the prototype has been built, this paper proposes a design optimization method to minimize vibration and deformation considering the effects of geometric errors before constructing the PKM. In this paper, geometric errors are described as parameter uncertainty because they are unknown in design stage. A five degree-of-freedom (DoF) PKM is taken to exemplify this method. Elastodynamic model is first formulated by a step-by-step strategy. On this basis, dynamic performances, including natural frequency, elastic deformation, and maximum stress, are analyzed. These analytical results are verified by finite-element simulation and experiment. Then, the necessity of concerning parameter uncertainty in optimization is addressed. Next, parameter uncertainty is added to the formulation of objectives and constraints by Monte Carlo simulation and response surface method. Finally, elastodynamic optimization of the 5-DoF PKM is implemented to rebuild a prototype which is robust to geometric errors and has minimal vibration and deformation. The proposed method can also be applied to accuracy improvement of any machines in practical applications.
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| 6. |
- Wang, Lei, et al.
(författare)
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Mechanochemical Formation of Protein Nanofibril: Graphene Nanoplatelet Hybrids and Their Thermoelectric Properties
- 2020
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Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 8:47, s. 17368-17378
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Tidskriftsartikel (refereegranskat)abstract
- Hybrids between biopolymeric materials and low-cost conductive carbon-based materials are interesting materials for applications in electronics, potentially reducing the need for materials that generate environmentally harmful electronic waste. Herein we investigate a scalable ball-milling method to form graphene nanoplatelets (GNPs) by milling graphite flakes with aqueous dispersions of proteins or protein nanofibrils (PNFs). Aqueous GNP dispersions with high concentrations (up to 3.2 mg mL(-1)) are obtained under appropriate conditions. The PNFs/proteins help to exfoliate graphite and stabilize the resulting GNP dispersions by electrostatic repulsion. PNFs are prepared from hen egg white lysozyme (HEWL) and beta-lactoglobulin (BLG). The GNP dispersions can be processed into free-standing films having an electrical conductivity of up to 110 S m(-1). Alternatively, the GNP dispersions can be drop-cast on PET substrates, resulting in mechanically flexible films having an electrical conductivity of up to 65 S m(-1). The drop-cast films are investigated regarding their thermoelectric properties, having Seebeck coefficients of about 50 mu V K-1. By annealing drop-cast films and thus carbonizing residual PNFs, an increase of electrical conductivity, coupled with a modest decrease in Seebeck coefficient, is obtained resulting in materials displaying power factors of up to 4.6 mu W m(-1) K-2.
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| 7. |
- Xin, Binbin, et al.
(författare)
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Growth and optical properties of CaxCoO2 thin films
- 2021
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Ingår i: Materials & design. - : Elsevier Science Ltd. - 0264-1275 .- 1873-4197. ; 210
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Tidskriftsartikel (refereegranskat)abstract
- The layered cobaltates A(x)CoO(2) (A = Li, Na, Ca, Ba, Sr) are of interest for energy applications such as thermoelectrics and batteries. However, it is challenging to obtain these phases in pure from as thin films. Here, phase-pure CaxCoO2 (x similar to 0.5) thin films were obtained by annealing of Ca(OH)(2)/Co3O4 multilayers made by moisture treatment of sputter-deposited CaO/Co3O4 multilayer films. The pure CaxCoO2 thin films exhibit an average optical transmittance of approximately 36% in the visible region and greater than 70% in the near-infrared (NIR) region. In addition, the electrical conductivity can be increased by incorporating a secondary Ca3Co4O9 phase into the CaxCoO2 thin film without large changes in optical properties and Seebeck coefficient. (C) 2021 The Authors. Published by Elsevier Ltd.
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| 8. |
- Xin, Binbin, et al.
(författare)
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Mechanically Flexible Thermoelectric Hybrid Thin Films by Introduction of PEDOT:PSS in Nanoporous Ca3Co4O9
- 2022
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 7:27, s. 23988-23994
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Tidskriftsartikel (refereegranskat)abstract
- Nanoporous Ca3Co4O9 exhibits high thermoelectric properties and low thermal conductivity and can be made mechanically flexible by nanostructural design. To improve the mechanical flexibility with retained thermoelectric properties near room temperature, however, it is desirable to incorporate an organic filler in this nanoporous inorganic matrix material. Here, double-layer nanoporous Ca3Co4O9/PEDOT:PSS thin films were synthesized by spin-coating PEDOT:PSS into the nanopores. The obtained hybrid films exhibit high Seebeck coefficient (~+130 mu V/K) and thermoelectric power factor (0.75 mu W cm(-1) K-2) at room temperature with no deterioration in electrical properties after cyclic bending tests (98% preservation of electrical conductivity after 1000 cycles bending to a bending radius of 3 mm). Compared with the nanoporous Ca3Co4O9 thin film, the mechanical flexibility of the hybrid film can be effectively improved after hybrid with PEDOT:PSS with only a slight decrease of the thermoelectric properties.
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| 9. |
- Yang, Lulu, et al.
(författare)
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Association of accelerometer-derived circadian abnormalities and genetic risk with incidence of atrial fibrillation
- 2023
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Ingår i: npj Digital Medicine. - : Springer Nature. - 2398-6352. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- Evidence suggests potential links between circadian rhythm and atrial fibrillation (AF). However, whether circadian disruption can predict the onset of AF in the general population remains largely unknown. We aim to investigate the association of accelerometer-measured circadian rest-activity rhythm (CRAR, the most prominent circadian rhythm in humans) with the risk of AF, and examine joint associations and potential interactions of CRAR and genetic susceptibility with AF incidence. We include 62,927 white British participants of UK Biobank without AF at baseline. CRAR characteristics, including amplitude (strength), acrophase (timing of peak activity), pseudo-F (robustness), and mesor (height), are derived by applying an extended cosine model. Genetic risk is assessed with polygenic risk scores. The outcome is the incidence of AF. During a median follow-up of 6.16 years, 1920 participants developed AF. Low amplitude [hazard ratio (HR): 1.41, 95% confidence interval (CI): 1.25-1.58], delayed acrophase (HR: 1.24, 95% CI: 1.10-1.39), and low mesor (HR: 1.36, 95% CI: 1.21-1.52), but not low pseudo-F, are significantly associated with a higher risk of AF. No significant interactions between CRAR characteristics and genetic risk are observed. Joint association analyses reveal that participants with unfavourable CRAR characteristics and high genetic risk yield the highest risk of incident AF. These associations are robust after controlling for multiple testing and in a series of sensitivity analyses. Accelerometer-measured CRAR abnormalities, characterized by decreased strength and height, and later timing of peak activity of circadian rhythm, are associated with a higher risk of AF in the general population.
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