| 1. |
- Chen, Si, 1982-, et al.
(författare)
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Current gain enhancement for silicon-on-insulator lateral bipolar junction transistors operating at liquid-helium temperature
- 2020
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Ingår i: IEEE Electron Device Letters. - 0741-3106 .- 1558-0563. ; 41:6, s. 800-803
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Tidskriftsartikel (refereegranskat)abstract
- Conventional homojunction bipolar junction transistors (BJTs) are not suitable for cryogenic operation due to heavy doping-induced emitter band-gap narrowing and strong degradation in current gain (β) at low temperature. In this letter, we show that, on lateral version of the BJTs (LBJTs) fabricated on silicon-on-insulator (SOI) substrate, such β degradation can be mitigated by applying a substrate bias (V sub ), and a β over unity is achieved in a base current (I B ) range over 5 orders of magnitudes at 4.2 K, with a peak β ~ 100 demonstrated. The β improvement is explained by the enhanced electron tunneling through base region as a result of base barrier lowering and thinning by a positive Vsub, which leads to dramatic increase of collector current (IC) while IB is negligibly affected.
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| 2. |
- Gao, Yun, et al.
(författare)
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Microsecond-response perovskite light-emitting diodes for active-matrix displays
- 2024
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Ingår i: NATURE ELECTRONICS. - : NATURE PORTFOLIO. - 2520-1131. ; 7:6
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Tidskriftsartikel (refereegranskat)abstract
- Perovskite light-emitting diodes (PeLEDs) could be of use in the development of active-matrix displays. However, due to ion migration in crystal structure, PeLEDs have electroluminescence rise times over milliseconds, which is problematic for the development of high-refresh-rate displays. Here, we show that the electroluminescence rise time of PeLEDs can be reduced to microseconds using an individual-particle passivation strategy. The approach is based on BF4 - ions that can passivate every nanocrystal in a perovskite emissive layer during film deposition. It leads to a defect-free film with discrete nanostructure and excellent crystallinity, which inhibits ion migration. Our strategy can be applied in perovskite nanocrystal films with different colours: red (635 nm), green (520 nm) and blue (475 nm). These PeLEDs all demonstrate response times within microseconds and high external quantum efficiencies of 22.7%, 26.2% and 18.1%, respectively. This allows us to create microsecond-response active-matrix PeLEDs that exhibit external quantum efficiencies above 20% at a display brightness of 500-3,000 cd m-2 for green devices with a resolution of 30 pixels per inch. We also develop microsecond-response red, green and blue active-matrix displays with 90 pixels per inch. An individual-particle passivation strategy that reduces ion migration in perovskite nanocrystal film can be used to make high-refresh-rate active-matrix displays with microsecond response times reduced by three orders of magnitude compared with typical perovskite light-emitting diodes.
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| 3. |
- Cui, Chao, et al.
(författare)
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A Full Power Range ZVS Control Technology for Bidirectional Inductive Power Transfer System
- 2020
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Ingår i: IECON Proceedings (Industrial Electronics Conference). - 2577-1647 .- 2162-4704. ; 2020-October, s. 3861-3865
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Konferensbidrag (refereegranskat)abstract
- Inductive Power Transfer (IPT) technology has received extensive application research due to its safety and convenience. As a circuit topology with high efficiency and high controllability, dual active bridge (DAB) has been used in IPT system in recent years. In high-power applications, the EMI generated by the power device switch becomes more significant, which in turn negatively affects the efficiency and even the stability of the IPT system. There are several ways to reduce EMI. This article studies from the perspective of zero voltage switching (ZVS) of the DAB. When the duty cycle of the full bridge changes, the soft switching may not be maintained. This paper calculates and analyzes the ZVS operating range of the system under different situations. On this basis, a control method is proposed to achieve ZVS in the full power range of the system by adjusting the bilateral load angle. And the efficiency and stability of the system are improved. The correctness of the above theory and control method is verified through simulations.
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| 4. |
- Cui, Chao, et al.
(författare)
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Zero Voltage Switching for High Power Threephase Inductive Power Transfer with a Dual Active Bridge
- 2024
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Ingår i: IEEE Access. - 2169-3536 .- 2169-3536. ; 12, s. 7121-7133
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Tidskriftsartikel (refereegranskat)abstract
- Inductive power transfer (IPT) technology used for charging electric vehicles faces challenges in transferring high power because the power capacity and switching losses of high-frequency semiconductor devices are limiting factors. A three-phase system is a common high-power solution and soft switching is crucial for efficiency-oriented applications with high switching frequencies. In addition, dual active bridge (DAB) topology is a suitable topology for soft switching and has advantages in controllability and high efficiency. Therefore, to obtain higher power and efficiency, this paper studies the zero voltage switching (ZVS) of a three-phase inductive power transfer system with a dual active bridge. The three-phase IPT system with a DAB is different from both the normal three-phase DAB converter and the single-phase IPT system with a DAB, so their ZVS conditions and ranges are also different and need to be studied. This paper investigates the conditions and operating range for realizing zero voltage switching of the three-phase IPT system with a DAB. Based on this, the efficiency of the system is improved by changing the load angle between the primary and secondary sides. Finally, a 60 kW three-phase IPT system with a DAB is built, and the experimental verification of the study is conducted.
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| 5. |
- Gustavsson, Emil K., et al.
(författare)
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The annotation of GBA1 has been concealed by its protein-coding pseudogene GBAP1
- 2024
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Ingår i: Science Advances. - 2375-2548. ; 10:26, s. 1-20
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Tidskriftsartikel (refereegranskat)abstract
- Mutations in GBA1 cause Gaucher disease and are the most important genetic risk factor for Parkinson’s disease. However, analysis of transcription at this locus is complicated by its highly homologous pseudogene, GBAP1. We show that >50% of short RNA-sequencing reads mapping to GBA1 also map to GBAP1. Thus, we used long-read RNA sequencing in the human brain, which allowed us to accurately quantify expression from both GBA1 and GBAP1. We discovered significant differences in expression compared to short-read data and identify currently unannotated transcripts of both GBA1 and GBAP1. These included protein-coding transcripts from both genes that were translated in human brain, but without the known lysosomal function—yet accounting for almost a third of transcription. Analyzing brain-specific cell types using long-read and single-nucleus RNA sequencing revealed region-specific variations in transcript expression. Overall, these findings suggest nonlysosomal roles for GBA1 and GBAP1 with implications for our understanding of the role of GBA1 in health and disease.
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| 6. |
- Li, Zhongqiang, et al.
(författare)
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Heat Waves Alter Macrophyte-Derived Detrital Nutrients Release under Future Climate Warming Scenarios
- 2021
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 55:8, s. 5272-5281
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Tidskriftsartikel (refereegranskat)abstract
- In addition to a rise in global air and water mean temperatures, extreme climate events such as heat waves are increasing in frequency, intensity, and duration in many regions of the globe. Developing a mechanistic understanding of the impacts of heat waves on key ecosystem processes and how they differ from just an increase in mean temperatures is therefore of utmost importance for adaptive management against effects of global change. However, little is known about the impact of extreme events on freshwater ecosystem processes, particularly the decomposition of macrophyte detritus. We performed a mesocosm experiment to evaluate the impact of warming and heat waves on macrophyte detrital decomposition, applied as a fixed increment (+4 °C) above ambient and a fluctuating treatment with similar energy input, ranging from 0 to 6 °C above ambient (i.e., simulating heat waves). We showed that both warming and heat waves significantly accelerate dry mass loss of the detritus and carbon (C) release but found no significant differences between the two heated treatments on the effects on detritus dry mass loss and C release amount. This suggests that moderate warming indirectly enhanced macrophyte detritus dry mass loss and C release mainly by the amount of energy input rather than by the way in which warming was provided (i.e., by a fixed increment or in heat waves). However, we found significantly different amounts of nitrogen (N) and phosphorus (P) released between the two warming treatments, and there was an asymmetric response of N and P release patterns to the two warming treatments, possibly due to species-specific responses of decomposers to short-term temperature fluctuations and litter quality. Our results conclude that future climate scenarios can significantly accelerate organic matter decomposition and C, N, and P release from decaying macrophytes, and more importantly, there are asymmetric alterations in macrophyte-derived detrital N and P release dynamic. Therefore, future climate change scenarios could lead to alterations in N/P ratios in the water column via macrophyte decomposition processes and ultimately affect the structure and function of aquatic ecosystems, especially in the plankton community.
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| 7. |
- Wang, Xiaoyu, et al.
(författare)
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Associations of Insomnia With Insulin Resistance Traits : A Cross-sectional and Mendelian Randomization Study
- 2023
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : Endocrine Society. - 0021-972X .- 1945-7197. ; 108:8, s. e574-e582
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Tidskriftsartikel (refereegranskat)abstract
- Context: Insomnia is associated with insulin resistance (IR) in observational studies; however, whether insomnia is causally associated with IR remains unestablished.Objective: This study aims to estimate the causal associations of insomnia with IR and its related traits.Methods: In primary analyses, multivariable regression (MVR) and 1-sample Mendelian randomization (1SMR) analyses were performed to estimate the associations of insomnia with IR (triglyceride-glucose index and triglyceride to high-density lipoprotein cholesterol [TG/HDL-C] ratio) and its related traits (glucose level, TG, and HDL-C) in the UK Biobank. Thereafter, 2-sample MR (2SMR) analyses were used to validate the findings from primary analyses. Finally, the potential mediating effects of IR on the pathway of insomnia giving rise to type 2 diabetes (T2D) were examined using a 2-step MR design.Results: Across the MVR, 1SMR, and their sensitivity analyses, we found consistent evidence suggesting that more frequent insomnia symptoms were significantly associated with higher values of triglyceride-glucose index (MVR, beta = 0.024, P < 2.00E-16; 1SMR, beta = 0.343, P < 2.00E-16), TG/HDL-C ratio (MVR, beta = 0.016, P = 1.75E-13; 1SMR, beta = 0.445, P < 2.00E-16), and TG level (MVR, beta = 0.019 log mg/dL, P < 2.00E-16, 1SMR: beta = 0.289 log mg/dL, P < 2.00E-16) after Bonferroni adjustment. Similar evidence was obtained by using 2SMR, and mediation analysis suggested that about one-quarter (25.21%) of the association between insomnia symptoms and T2D was mediated by IR.Conclusions: This study provides robust evidence supporting that more frequent insomnia symptoms are associated with IR and its related traits across different angles. These findings indicate that insomnia symptoms can be served as a promising target to improve IR and prevent subsequent T2D.
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