| 31. |
- Neeraj, Kumar, et al.
(författare)
-
Inertial spin dynamics in ferromagnets
- 2021
-
Ingår i: Nature Physics. - : Springer Science and Business Media LLC. - 1745-2473 .- 1745-2481. ; 17, s. 245-250
-
Tidskriftsartikel (refereegranskat)abstract
- The understanding of how spins move and can be manipulated at pico- and femtosecond timescales has implications for ultrafast and energy-efficient data-processing and storage applications. However, the possibility of realizing commercial technologies based on ultrafast spin dynamics has been hampered by our limited knowledge of the physics behind processes on this timescale. Recently, it has been suggested that inertial effects should be considered in the full description of the spin dynamics at these ultrafast timescales, but a clear observation of such effects in ferromagnets is still lacking. Here, we report direct experimental evidence of intrinsic inertial spin dynamics in ferromagnetic thin films in the form of a nutation of the magnetization at a frequency of ~0.5 THz. This allows us to reveal that the angular momentum relaxation time in ferromagnets is on the order of 10 ps.
|
|
| 32. |
- Qing, Jian, et al.
(författare)
-
Aligned and Graded Type-II Ruddlesden-Popper Perovskite Films for Efficient Solar Cells
- 2018
-
Ingår i: Advanced Energy Materials. - : WILEY-V C H VERLAG GMBH. - 1614-6832 .- 1614-6840. ; 8:21
-
Tidskriftsartikel (refereegranskat)abstract
- Recently, Ruddlesden-Popper perovskites (RPPs) have attracted increasing interests due to their promising stability. However, the efficiency of solar cells based on RPPs is much lower than that based on 3D perovskites, mainly attributed to their poor charge transport. Herein, a simple yet universal method for controlling the quality of RPP films by a synergistic effect of two additives in the precursor solution is presented. RPP films achieved by this method show (a) high quality with uniform morphology, enhanced crystallinity, and reduced density of sub-bandgap states, (b) vertically oriented perovskite frameworks that facilitate efficient charge transport, and (c) type-II band alignment that favors self-driven charge separation. Consequently, a hysteresis-free RPP solar cell with a power conversion efficiency exceeding 12%, which is much higher than that of the control device (1.5%), is achieved. The findings will spur new developments in the fabrication of high-quality, aligned, and graded RPP films essential for realizing efficient and stable perovskite solar cells.
|
|
| 33. |
|
|
| 34. |
- Tang, Sui, et al.
(författare)
-
Association of plant-based diet index with sleep quality in middle-aged and older adults : The Healthy Dance Study
- 2023
-
Ingår i: Sleep Health. - : Elsevier. - 2352-7218 .- 2352-7226. ; 9:5, s. 698-703
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives: To investigate the association between plant-based diet indices and sleep quality in Chinese middle-aged and older adults.Methods: The study included 2424 participants aged 45 years and older. Dietary data were collected using a semi-quantitative food frequency questionnaire, and sleep quality was assessed by the Pittsburgh Sleep Quality Index scale. Plant-based diet was categorized based on 3 indices (score range, 17-85) covering 17 food groups: the overall plant-based diet index, healthful plant-based diet index, and unhealthful plant-based diet index. The associations between these plant-based diet indices and sleep quality were examined using logistic and linear regression analyses.Results: After controlling for sociodemographic, lifestyle, and multiple disease-related factors, participants in the highest quartile of the healthful plant-based diet index had 0.55 higher odds of better sleep quality (95% CI: 0.42, 0.72; P-trend < .001). In contrast, participants in the highest quartile of the unhealthful plant-based diet index had 2.03 higher odds of poor sleep quality (95% CI: 1.51, 2.72; P-trend < .001). In addition, plant-based diet index and healthful plant-based diet index were inversely associated with Pittsburgh Sleep Quality Index scores, while unhealthful plant-based diet index and Pittsburgh Sleep Quality Index scores were positively associated.Conclusions: We found unhealthy plant-based diets are significantly associated with poor sleep quality. Adherence to overall plant-based diets, especially healthy plant-based diets, was positively associated with optimal sleep quality.(c) 2023 National Sleep Foundation. Published by Elsevier Inc. All rights reserved.
|
|
| 35. |
- Zhang, Hao, et al.
(författare)
-
Papillomavirus type 16 E6/E7 and human telomerase reverse transcriptase in esophageal cell immortalization and early transformation
- 2007
-
Ingår i: Cancer Letters. - : Elsevier BV. - 1872-7980 .- 0304-3835. ; 245:1-2, s. 184-194
-
Tidskriftsartikel (refereegranskat)abstract
- Infection with high-risk human papillomavirus (HPV) has been implicated in the pathogenesis of esophageal squamous cell carcinoma, and up-regulation of telomerase in esophageal adenocarcinoma. We immortalized normal esophageal epithelial cells by over-expression of the HPV16 E6/E7 and human telomerase reverse transcriptase (hTERT) genes. HPV16 E6/E7-induced immortalization was accompanied by reduced RB and p53, but increased p16 and p21, protein expression. hTERT-immortalized cells had unaffected RB and p53, but significantly decreased p16 and p21, protein expression. Aurora-A protein was also upregulated in E6E7 immortalized cells, and to a less extent in hTERT immortalized cells. Fluorescence in situ hybridization showed that the Aurora-A gene locus was amplified in E6E7 immortalized cells, which might account in part for the Aurora-A overexpression. These molecular changes led to an abrogation of the G2 checkpoint. E6E7 and hTERT immortalized esophageal cells recapitulated many of the molecular changes observed in esophageal carcinomas, where RB and p53 are frequently downregulated. However, down-regulation of p16 and p21 occurred frequently in esophageal cancer, owing to aberrant gene promoter methylation. We showed in the immortalized cells that aberrant methylation had not yet set in, suggesting that promoter methylation might not be necessary for cellular immortalization. In addition to supporting the role of HPV and telomerase in esophageal carcinogenesis, our cell lines may also be useful in vitro models for further studies of esophageal carcinogenesis.
|
|
| 36. |
- Zhang, Jibin, et al.
(författare)
-
Highly Luminescent and Stable CsPbI3 Perovskite Nanocrystals with Sodium Dodecyl Sulfate Ligand Passivation for Red-Light-Emitting Diodes
- 2021
-
Ingår i: Journal of Physical Chemistry Letters. - : AMER CHEMICAL SOC. - 1948-7185 .- 1948-7185. ; 12:9, s. 2437-2443
-
Tidskriftsartikel (refereegranskat)abstract
- CsPbI3 perovskite nanocrystals (NCs) have recently emerged as promising materials for optoelectronic devices because of their superior properties. However, the poor stability of the CsPbI3 NCs induced by easy ligand desorption represents a key issue limiting their practical applications. Herein, we report stable and highly luminescent black-phase CsPbI3 NCs passivated by novel ligands of sodium dodecyl sulfate (SDS). Theoretical calculation results reveal a stronger adsorption energy of SDS molecules at the CsPbI3 surface than that of commonly used oleic acid. As a result, the defect formation caused by the ligand loss during the purification process is greatly suppressed. The optimized SDS- CsPbI3 NCs exhibit significantly reduced surface defects, much enhanced stability, and superior photoluminescence efficiency. The red perovskite light-emitting diodes based on the SDS-CsPbI3 NCs demonstrate an external quantum efficiency of 8.4%, which shows a 4-fold improvement compared to the devices based on the oleic acid-modified CsPbI3 NCs.
|
|
| 37. |
- Zhang, Jibin, et al.
(författare)
-
Ligand-Induced Cation-p Interactions Enable High-Efficiency, Bright, and Spectrally Stable Rec. 2020 Pure-Red Perovskite Light-Emitting Diodes
- 2023
-
Ingår i: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095.
-
Tidskriftsartikel (refereegranskat)abstract
- Achieving high-performance perovskite light-emitting diodes (PeLEDs) with pure-red electroluminescence for practical applications remains a critical challenge because of the problematic luminescence property and spectral instability of existing emitters. Herein, high-efficiency Rec. 2020 pure-red PeLEDs, simultaneously exhibiting exceptional brightness and spectral stability, based on CsPb(Br/I)(3) perovskite nanocrystals (NCs) capping with aromatic amino acid ligands featuring cation-pi interactions, are reported. It is proven that strong cation-pi interactions between the PbI6-octahedra of perovskite units and the electron-rich indole ring of tryptophan (TRP) molecules not only chemically polish the imperfect surface sites, but also markedly increase the binding affinity of the ligand molecules, leading to high photoluminescence quantum yields and greatly enhanced spectral stability of the CsPb(Br/I)(3) NCs. Moreover, the incorporation of small-size aromatic TRP ligands ensures superior charge-transport properties of the assembled emissive layers. The resultant devices emitting at around 635 nm demonstrate a champion external quantum efficiency of 22.8%, a max luminance of 12 910 cd m(-2), and outstanding spectral stability, representing one of the best-performing Rec. 2020 pure-red PeLEDs achieved so far.
|
|
| 38. |
- Zhang, Qun, et al.
(författare)
-
The Realistic Domain Structure of As-Synthesized Graphene Oxide from Ultrafast Spectroscopy
- 2013
-
Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 135:33, s. 12468-12474
-
Tidskriftsartikel (refereegranskat)abstract
- Graphene oxide (GO) is an attractive alternative for large-scale production of graphene, but its general structure is still under debate due to its complicated nonstoichiometric nature. Here we perform a set of femto-second pump-probe experiments on as-synthesized GO to extrapolate structural information in situ. Remarkably, it is observed that, in these highly oxidized GO samples, the ultrafast graphene-like dynamics intrinsic to pristine graphene is completely dominant over a wide energy region and can be modified by the localized impurity states and the electron-phonon coupling under certain conditions. These observations, combined with the X-ray photoelectron spectroscopy analysis and control experiments, lead to an important conclusion that GO consists of two types of domain, namely the carbon-rich graphene-like domain and the oxygen-rich domain. This study creates a new understanding of the realistic domain structure and properties of as-synthesized GO, offering useful guidance for future applications based on chemically modified/functionalized graphenes.
|
|
| 39. |
- Zhang, Sai, et al.
(författare)
-
Genome-wide identification of the genetic basis of amyotrophic lateral sclerosis
- 2022
-
Ingår i: Neuron. - : Elsevier BV. - 0896-6273. ; 110:6, s. 11-1008
-
Tidskriftsartikel (refereegranskat)abstract
- Amyotrophic lateral sclerosis (ALS) is a complex disease that leads to motor neuron death. Despite heritability estimates of 52%, genome-wide association studies (GWASs) have discovered relatively few loci. We developed a machine learning approach called RefMap, which integrates functional genomics with GWAS summary statistics for gene discovery. With transcriptomic and epigenetic profiling of motor neurons derived from induced pluripotent stem cells (iPSCs), RefMap identified 690 ALS-associated genes that represent a 5-fold increase in recovered heritability. Extensive conservation, transcriptome, network, and rare variant analyses demonstrated the functional significance of candidate genes in healthy and diseased motor neurons and brain tissues. Genetic convergence between common and rare variation highlighted KANK1 as a new ALS gene. Reproducing KANK1 patient mutations in human neurons led to neurotoxicity and demonstrated that TDP-43 mislocalization, a hallmark pathology of ALS, is downstream of axonal dysfunction. RefMap can be readily applied to other complex diseases.
|
|
| 40. |
- Zhao, Haifeng, et al.
(författare)
-
High-Brightness Perovskite Light-Emitting Diodes Based on FAPbBr(3) Nanocrystals with Rationally Designed Aromatic Ligands
- 2021
-
Ingår i: ACS Energy Letters. - : AMER CHEMICAL SOC. - 2380-8195. ; 6:7, s. 2395-2403
-
Tidskriftsartikel (refereegranskat)abstract
- Despite rapid developments of light-emitting diodes (LEDs) based on emerging perovskite nanocrystals (PeNCs), it remains challenging to achieve devices with integrated high efficiencies and high brightness because of the insulating long-chain ligands used for the PeNCs. Herein, we develop highly luminescent and stable formamidinium lead bromide PeNCs capped with rationally designed short aromatic ligands of 2-naphthalenesulfonic acid (NSA) for LEDs. Compared with commonly used oleic acid ligands, the NSA molecules not only preserve the surface properties of the PeNCs during the purification but also notably improve the electrical properties of the assembled emissive layers, ensuring efficient charge injection/transport in the devices. The resulting champion LED with electroluminescence approaching the Rec. 2020 green primary color demonstrates a high brightness of 67 115 cd cm(-2) and a peak external quantum efficiency of 19.2%. More impressively, the device shows negligibly decreased efficiency at an elevated brightness of 20 000 cd cm(-2) and a well-retained efficiency of over 10% at around 65 000 cd cm(-2), presenting a breakthrough in LEDs based on PeNCs.
|
|
