| 1. |
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| 2. |
- Lei, Ming, et al.
(författare)
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Successive Interference Cancellation for Throughput Maximization in Wireless Powered Communication Networks
- 2016
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Ingår i: 2016 IEEE 84TH VEHICULAR TECHNOLOGY CONFERENCE (VTC FALL). - : IEEE. - 9781509017010
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Konferensbidrag (refereegranskat)abstract
- In wireless powered communication networks (WPCNs), each user node, e.g., wireless powered sensor, is capable of either harvesting energy from a power station or transmitting data to a sink node. In the previous works, time division multiple access (TDMA) is typically used for transmission scheduling in WPCNs, that is, only one node can transmit data in one time slot. The spectrum efficiency is therefore limited by this orthogonality in time-domain scheduling. In this paper, to maximize the throughput in WPCNs, we present a new scheduling approach for energy harvesting and data transmission. Unlike TDMA, we consider that multiple nodes can simultaneously transmit their data in the same time slot, and the signals are separated at the sink node by performing successive interference cancellation (SIC). We formulate the throughput maximization problem as a linear programming problem. For solving the large scale instances, we design an algorithmic framework based on column generation. Numerical results demonstrate that compared to the TDMA based scheduling approach, substantial throughput improvement is achieved by the proposed algorithm.
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| 3. |
- Feng, Zhenhua, et al.
(författare)
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Multicore-Fiber-Enabled WSDM Optical Access Network With Centralized Carrier Delivery and RSOA-Based Adaptive Modulation
- 2015
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Ingår i: IEEE PHOTONICS JOURNAL. - : Institute of Electrical and Electronics Engineers (IEEE). - 1943-0655. ; 7:4
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Tidskriftsartikel (refereegranskat)abstract
- We proposed and experimentally demonstrated a wavelength-space division multiplexing (WSDM) optical access network architecture with centralized optical carrier delivery utilizing multicore fibers (MCFs) and adaptive modulation based on reflective semiconductor amplifier (RSOA). In our experiment, five of the outer cores are used for undirectional downstream (DS) transmission only, whereas the remaining outer core is utilized as a dedicated channel to transmit upstream (US) signals. Optical carriers for US are delivered from the optical line terminal (OLT) to the optical network unit (ONU) via the inner core and then transmitted back to the OLT after amplification and modulation by the RSOA in the colorless ONU side. The mobile backhaul (MB) service is also supported by the inner core. Wavelengths used in US transmission should be different from that of the MB in order to avoid the Rayleigh backscattering effect in bidirectional transmission. With quadrature phase-shift keying-orthogonal frequency-division multiplexing (QPSK-OFDM) modulation format, the aggregation DS capacity reaches 250 Gb/s using five outer cores and ten wavelengths, and it can be further scaled to 1 Tb/s using 20 wavelengths modulated with 16 QAM-OFDM. For US transmission, 2.5 Gb/s QPSK-OFDM transmission can be achieved just using a low-bandwidth RSOA, and adaptive modulation is applied to the RSOA to further enhance the US data rate to 3.12 Gb/s. As an emulation of high-speed MB transmission, 48 Gb/s inphase and quadrature (IQ) modulated popularization division multiplexing (PDM)-QPSK signal is transmitted in the inner core of MCF and coherently detected in the OLT side. Both DS and US optical signals exhibit acceptable performance with sufficient power budget.
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| 4. |
- Santangelo, James S., et al.
(författare)
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Global urban environmental change drives adaptation in white clover
- 2022
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 375
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Tidskriftsartikel (refereegranskat)abstract
- Urbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors. Urban-rural gradients were associated with the evolution of clines in defense in 47% of cities throughout the world. Variation in the strength of clines was explained by environmental changes in drought stress and vegetation cover that varied among cities. Sequencing 2074 genomes from 26 cities revealed that the evolution of urban-rural dines was best explained by adaptive evolution, but the degree of parallel adaptation varied among cities. Our results demonstrate that urbanization leads to adaptation at a global scale.
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| 5. |
- Tan, Wei, et al.
(författare)
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High-efficiency frequency upconversion of 1.5 mu m laser based on a doubly resonant external ring cavity with a low finesse for signal field
- 2017
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Ingår i: Applied physics. B, Lasers and optics (Print). - : Springer. - 0946-2171 .- 1432-0649. ; 123:2
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Tidskriftsartikel (refereegranskat)abstract
- A doubly resonant external ring cavity with a low finesse for the signal field is used to improve the frequency upconversion efficiency of a weak 1583 nm signal laser to 636 nm by mixing with a resonance power enhanced 1064 nm pump laser in a 25 mm periodically poled lithium niobate crystal. The process of frequency upconversion is described and optimized by the doubly resonant cavity-enhanced sum frequency generation theory under the condition of undepleted pump approximation. By selecting the suitable reflectivity of the signal input mirror and the incident pump power, a cavity-enhanced frequency conversion efficiency of 94.6% was obtained for signal powers up to 25 mW with an input pump power of 780 mW.
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| 6. |
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- 2019
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Tidskriftsartikel (refereegranskat)
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| 7. |
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| 8. |
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| 9. |
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| 10. |
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| 11. |
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| 12. |
- Ando, Koji, et al.
(författare)
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KCNJ8/ABCC9-containing K-ATP channel modulates brain vascular smooth muscle development and neurovascular coupling
- 2022
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Ingår i: Developmental Cell. - : Elsevier. - 1534-5807 .- 1878-1551. ; 57:11, s. 1383-1399.e7
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Tidskriftsartikel (refereegranskat)abstract
- Loss- or gain-of-function mutations in ATP-sensitive potassium channel (K-ATP)-encoding genes, KCNJ8 and ABCC9, cause human central nervous system disorders with unknown pathogenesis. Here, using mice, zebrafish, and cell culture models, we investigated cellular and molecular causes of brain dysfunctions derived from altered K-ATP channel function. We show that genetic/chemical inhibition or activation of KCNJ8/ABCC9-containing K-ATP channel function leads to brain-selective suppression or promotion of arterial/arteriolar vascular smooth muscle cell (VSMC) differentiation, respectively. We further show that brain VSMCs develop from KCNJ8/ABCC9-containing K-ATP channel-expressing mural cell progenitor and that K-ATP channel cell autonomously regulates VSMC differentiation through modulation of intracellular Ca2+ oscillation via voltage-dependent calcium channels. Consistent with defective VSMC development, Kcnj8 knockout mice showed deficiency in vasoconstrictive capacity and neuronal-evoked vasodilation leading to local hyperemia. Our results demonstrate a role for KCNJ8/ABCC9-containing K-ATP channels in the differentiation of brain VSMC, which in turn is necessary for fine-tuning of cerebral blood flow.
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| 13. |
- Bu, Junling, et al.
(författare)
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Catalytic promiscuity of O-methyltransferases from Corydalis yanhusuo leading to the structural diversity of benzylisoquinoline alkaloids
- 2022
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Ingår i: Horticulture Research. - : Oxford University Press (OUP). - 2662-6810 .- 2052-7276. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- O-methyltransferases play essential roles in producing structural diversity and improving the biological properties of benzylisoquinoline alkaloids (BIAs) in plants. In this study, Corydalis yanhusuo, a plant used in traditional Chinese medicine due to the analgesic effects of its BIA-active compounds, was employed to analyze the catalytic characteristics of O-methyltransferases in the formation of BIA diversity. Seven genes encoding O-methyltransferases were cloned, and functionally characterized using seven potential BIA substrates. Specifically, an O-methyltransferase (CyOMT2) with highly efficient catalytic activity of both 4′- and 6-O-methylations of 1-BIAs was found. CyOMT6 was found to perform two sequential methylations at both 9- and 2-positions of the essential intermediate of tetrahydroprotoberberines, (S)-scoulerine. Two O-methyltransferases (CyOMT5 and CyOMT7) with wide substrate promiscuity were found, with the 2-position of tetrahydroprotoberberines as the preferential catalytic site for CyOMT5 (named scoulerine 2-O-methyltransferase) and the 6-position of 1-BIAs as the preferential site for CyOMT7. In addition, results of integrated phylogenetic molecular docking analysis and site-directed mutation suggested that residues at sites 172, 306, 313, and 314 in CyOMT5 are important for enzyme promiscuity related to O-methylations at the 6- and 7-positions of isoquinoline. Cys at site 253 in CyOMT2 was proved to promote the methylation activity of the 6-position and to expand substrate scopes. This work provides insight into O-methyltransferases in producing BIA diversity in C. yanhusuo and genetic elements for producing BIAs by metabolic engineering and synthetic biology.
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| 14. |
- Chen, Gongbo, et al.
(författare)
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All-cause, cardiovascular, and respiratory mortality and wildfire-related ozone : a multicountry two-stage time series analysis
- 2024
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Ingår i: The Lancet Planetary Health. - : Elsevier. - 2542-5196. ; 8:7, s. e452-e462
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Tidskriftsartikel (refereegranskat)abstract
- Background: Wildfire activity is an important source of tropospheric ozone (O3) pollution. However, no study to date has systematically examined the associations of wildfire-related O3 exposure with mortality globally.Methods: We did a multicountry two-stage time series analysis. From the Multi-City Multi-Country (MCC) Collaborative Research Network, data on daily all-cause, cardiovascular, and respiratory deaths were obtained from 749 locations in 43 countries or areas, representing overlapping periods from Jan 1, 2000, to Dec 31, 2016. We estimated the daily concentration of wildfire-related O3 in study locations using a chemical transport model, and then calibrated and downscaled O3 estimates to a resolution of 0·25° × 0·25° (approximately 28 km2 at the equator). Using a random-effects meta-analysis, we examined the associations of short-term wildfire-related O3 exposure (lag period of 0–2 days) with daily mortality, first at the location level and then pooled at the country, regional, and global levels. Annual excess mortality fraction in each location attributable to wildfire-related O3 was calculated with pooled effect estimates and used to obtain excess mortality fractions at country, regional, and global levels.Findings: Between 2000 and 2016, the highest maximum daily wildfire-related O3 concentrations (≥30 μg/m3) were observed in locations in South America, central America, and southeastern Asia, and the country of South Africa. Across all locations, an increase of 1 μg/m3 in the mean daily concentration of wildfire-related O3 during lag 0–2 days was associated with increases of 0·55% (95% CI 0·29 to 0·80) in daily all-cause mortality, 0·44% (–0·10 to 0·99) in daily cardiovascular mortality, and 0·82% (0·18 to 1·47) in daily respiratory mortality. The associations of daily mortality rates with wildfire-related O3 exposure showed substantial geographical heterogeneity at the country and regional levels. Across all locations, estimated annual excess mortality fractions of 0·58% (95% CI 0·31 to 0·85; 31 606 deaths [95% CI 17 038 to 46 027]) for all-cause mortality, 0·41% (–0·10 to 0·91; 5249 [–1244 to 11 620]) for cardiovascular mortality, and 0·86% (0·18 to 1·51; 4657 [999 to 8206]) for respiratory mortality were attributable to short-term exposure to wildfire-related O3.Interpretation: In this study, we observed an increase in all-cause and respiratory mortality associated with short-term wildfire-related O3 exposure. Effective risk and smoke management strategies should be implemented to protect the public from the impacts of wildfires.
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| 15. |
- Chen, Gongbo, et al.
(författare)
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Mortality risk attributable to wildfire-related PM2·5 pollution : a global time series study in 749 locations
- 2021
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Ingår i: The Lancet Planetary Health. - : Elsevier. - 2542-5196. ; 5:9, s. e579-e587
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Many regions of the world are now facing more frequent and unprecedentedly large wildfires. However, the association between wildfire-related PM2·5 and mortality has not been well characterised. We aimed to comprehensively assess the association between short-term exposure to wildfire-related PM2·5 and mortality across various regions of the world.METHODS: For this time series study, data on daily counts of deaths for all causes, cardiovascular causes, and respiratory causes were collected from 749 cities in 43 countries and regions during 2000-16. Daily concentrations of wildfire-related PM2·5 were estimated using the three-dimensional chemical transport model GEOS-Chem at a 0·25° × 0·25° resolution. The association between wildfire-related PM2·5 exposure and mortality was examined using a quasi-Poisson time series model in each city considering both the current-day and lag effects, and the effect estimates were then pooled using a random-effects meta-analysis. Based on these pooled effect estimates, the population attributable fraction and relative risk (RR) of annual mortality due to acute wildfire-related PM2·5 exposure was calculated.FINDINGS: 65·6 million all-cause deaths, 15·1 million cardiovascular deaths, and 6·8 million respiratory deaths were included in our analyses. The pooled RRs of mortality associated with each 10 μg/m3 increase in the 3-day moving average (lag 0-2 days) of wildfire-related PM2·5 exposure were 1·019 (95% CI 1·016-1·022) for all-cause mortality, 1·017 (1·012-1·021) for cardiovascular mortality, and 1·019 (1·013-1·025) for respiratory mortality. Overall, 0·62% (95% CI 0·48-0·75) of all-cause deaths, 0·55% (0·43-0·67) of cardiovascular deaths, and 0·64% (0·50-0·78) of respiratory deaths were annually attributable to the acute impacts of wildfire-related PM2·5 exposure during the study period.INTERPRETATION: Short-term exposure to wildfire-related PM2·5 was associated with increased risk of mortality. Urgent action is needed to reduce health risks from the increasing wildfires.
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| 16. |
- Chen, Yi-Jing, et al.
(författare)
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Molecular Engineering of Perylene Diimide Polymers with a Robust Built-in Electric Field for Enhanced Solar-Driven Water Splitting
- 2023
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Ingår i: Angewandte Chemie International Edition. - : WILEY-V C H VERLAG GMBH. - 1433-7851 .- 1521-3773.
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Tidskriftsartikel (refereegranskat)abstract
- The built-in electric field of the polymer semiconductors could be regulated by the dipole moment of its building blocks, thereby promoting the separation of photogenerated carriers and achieving efficient solar-driven water splitting. Herein, three perylene diimide (PDI) polymers, namely oPDI, mPDI and pPDI, are synthesized with different phenylenediamine linkers. Notably, the energy level structure, light-harvesting efficiency, and photogenerated carrier separation and migration of polymers are regulated by the orientation of PDI unit. Among them, oPDI enables a large dipole moment and robust built-in electric field, resulting in enhanced solar-driven water splitting performance. Under simulated sunlight irradiation, oPDI exhibits the highest photocurrent of 115.1 mu A cm-2 for photoelectrochemical oxygen evolution, which is 11.5 times that of mPDI, 26.8 times that of pPDI and 104.6 times that of its counterparts PDI monomer at the same conditions. This work provides a strategy for designing polymers by regulating the orientation of structural units to construct efficient solar energy conversion systems. Three perylene diimide (PDI) polymers were designed and synthesized such that the molecular orientation of the PDI units was regulated to create and modulate their built-in electric fields. Due to the large dipole moment and interfacial electric field, oPDI enables an extraordinary photocurrent density of 115.1 mu A & sdot; cm-2, which is 11.5 and 26.8 times that of mPDI and pPDI, respectively.image
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| 17. |
- Chen, Yao Tong, et al.
(författare)
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Giant-atom effects on population and entanglement dynamics of Rydberg atoms in the optical regime
- 2023
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Ingår i: Physical Review Research. - 2643-1564. ; 5:4
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Tidskriftsartikel (refereegranskat)abstract
- Giant atoms are attracting interest as an emerging paradigm in the quantum optics of engineered waveguides. At variance with the well-known artificial giant atoms for microwave photonics, here we propose the archetype of a giant atom working in the optical regime by considering a pair of interacting Rydberg atoms coupled to a photonic crystal waveguide (PCW) and also driven by a coherent field. Giant-atom effects are observed as a phase-dependent decay of the double Rydberg excitation during the initial evolution stage while a nontrivial internal entanglement is exhibited at later times. Such an entanglement onset occurs in the presence of intrinsic atomic decay toward nonguided vacuum modes and is accompanied by antibunching in the emitted photons. Our predictions should be observable in current Rydberg-PCW experiments and may open the way toward giant-atom optical photonics for quantum information processing.
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| 18. |
- Chen, Yao Tong, et al.
(författare)
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Single-photon manipulations based on optically controlled chiral couplings in waveguide structures of Rydberg giant atoms
- 2024
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Ingår i: Physical Review A. - 2469-9934 .- 2469-9926. ; 109:6
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Tidskriftsartikel (refereegranskat)abstract
- Two interacting Rydberg atoms coupled to a waveguide may realize a giant-atom platform that exhibits controllable (phase-dependent) chirality through which the direction of nonreciprocally scattered photons can be switched on demand, e.g., by the geometrical tuning of an external driving field. In our platform, at variance with traditional setups, the chirality arises from a simple optical implementation of the local phase difference between two coupling points of the Rydberg giant atom. When employing two (or more) driving fields, this platform can also be used as a frequency converter with its strongly asymmetric efficiency being significantly enhanced via the chiral couplings. Our Rydberg giant-atom platform is well suited for chiral quantum optics applications and further offers direct scalability for reaching tunable frequency conversion in the optical domain.
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| 19. |
- Du, Qian, et al.
(författare)
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Porcine circovirus type 2 infection promotes the SUMOylation of nucleophosmin-1 to facilitate the viral circular single-stranded DNA replication
- 2024
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Ingår i: PLoS Pathogens. - : Public Library of Science (PLoS). - 1553-7366 .- 1553-7374. ; 20:2
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Tidskriftsartikel (refereegranskat)abstract
- The mechanism of genome DNA replication in circular single-stranded DNA viruses is currently a mystery, except for the fact that it undergoes rolling-circle replication. Herein, we identified SUMOylated porcine nucleophosmin-1 (pNPM1), which is previously reported to be an interacting protein of the viral capsid protein, as a key regulator that promotes the genome DNA replication of porcine single-stranded DNA circovirus. Upon porcine circovirus type 2 (PCV2) infection, SUMO2/3 were recruited and conjugated with the K263 site of pNPM1's C-terminal domain to SUMOylate pNPM1, subsequently, the SUMOylated pNPM1 were translocated in nucleoli to promote the replication of PCV2 genome DNA. The mutation of the K263 site reduced the SUMOylation levels of pNPM1 and the nucleolar localization of pNPM1, resulting in a decrease in the level of PCV2 DNA replication. Meanwhile, the mutation of the K263 site prevented the interaction of pNPM1 with PCV2 DNA, but not the interaction of pNPM1 with PCV2 Cap. Mechanistically, PCV2 infection increased the expression levels of Ubc9, the only E2 enzyme involved in SUMOylation, through the Cap-mediated activation of ERK signaling. The upregulation of Ubc9 promoted the interaction between pNPM1 and TRIM24, a potential E3 ligase for SUMOylation, thereby facilitating the SUMOylation of pNPM1. The inhibition of ERK activation could significantly reduce the SUMOylation levels and the nucleolar localization of pNPM1, as well as the PCV2 DNA replication levels. These results provide new insights into the mechanism of circular single-stranded DNA virus replication and highlight NPM1 as a potential target for inhibiting PCV2 replication. Different types of DNA viruses employ different mechanisms to replicate their genome DNA. Porcine circovirus type 2 (PCV2) is the most representative circular single-stranded DNA virus that harms the pig industry all over the world. In this study, we found that the PCV2 Cap interacting protein pNPM1 also interacts with PCV2 DNA in a SUMOylated form to promote PCV2 DNA replication. The SUMOylation of pNPM1 at the conserved K263 site is critical for the interaction of pNPM1 with PCV2 DNA and the replication of PCV2 DNA. Furthermore, we found that PCV2 infection promotes the SUMO2/3 mediated SUMOylation of pNPM1, while does not significantly alter the expression level of pNPM1. PCV2 Cap is the major component that promotes pNPM1 SUMOylation by activating ERK/Ubc9/TRIM24 signalings. These results contribute to a better understanding of the replication mechanism of circular single-stranded DNA viruses, particularly PCV2.
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| 20. |
- Fang, Li Tai, et al.
(författare)
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Establishing community reference samples, data and call sets for benchmarking cancer mutation detection using whole-genome sequencing
- 2021
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Ingår i: Nature Biotechnology. - : Springer Nature. - 1087-0156 .- 1546-1696. ; 39:9, s. 1151-1160
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Tidskriftsartikel (refereegranskat)abstract
- Tumor-normal paired DNA samples from a breast cancer cell line and a matched lymphoblastoid cell line enable calibration of clinical sequencing pipelines and benchmarking 'tumor-only' or 'matched tumor-normal' analyses. The lack of samples for generating standardized DNA datasets for setting up a sequencing pipeline or benchmarking the performance of different algorithms limits the implementation and uptake of cancer genomics. Here, we describe reference call sets obtained from paired tumor-normal genomic DNA (gDNA) samples derived from a breast cancer cell line-which is highly heterogeneous, with an aneuploid genome, and enriched in somatic alterations-and a matched lymphoblastoid cell line. We partially validated both somatic mutations and germline variants in these call sets via whole-exome sequencing (WES) with different sequencing platforms and targeted sequencing with >2,000-fold coverage, spanning 82% of genomic regions with high confidence. Although the gDNA reference samples are not representative of primary cancer cells from a clinical sample, when setting up a sequencing pipeline, they not only minimize potential biases from technologies, assays and informatics but also provide a unique resource for benchmarking 'tumor-only' or 'matched tumor-normal' analyses.
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| 21. |
- He, Yibo, et al.
(författare)
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A subset of antibodies targeting citrullinated proteins confers protection from rheumatoid arthritis.
- 2023
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Ingår i: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Although elevated levels of anti-citrullinated protein antibodies (ACPAs) are a hallmark of rheumatoid arthritis (RA), the in vivo functions of these antibodies remain unclear. Here, we have expressed monoclonal ACPAs derived from patients with RA, and analyzed their functions in mice, as well as their specificities. None of the ACPAs showed arthritogenicity nor induced pain-associated behavior in mice. However, one of the antibodies, clone E4, protected mice from antibody-induced arthritis. E4 showed a binding pattern restricted to skin, macrophages and dendritic cells in lymphoid tissue, and cartilage derived from mouse and human arthritic joints. Proteomic analysis confirmed that E4 strongly binds to macrophages and certainRA synovial fluid proteins such as α-enolase. The protective effect of E4 was epitope-specific and dependent on the interaction between E4-citrullinated α-enolase immune complexes with FCGR2B on macrophages, resulting in increased IL-10 secretion and reduced osteoclastogenesis. These findings suggest that a subset of ACPAs have therapeutic potential in RA.
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| 22. |
- Jin, Lei, et al.
(författare)
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Engineering Interfacial Structure in “Giant” PbS/CdS Quantum Dots for Photoelectrochemical Solar Energy Conversion
- 2016
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Ingår i: Nano Energy. - : Elsevier BV. - 2211-2855. ; 30, s. 531-541
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Tidskriftsartikel (refereegranskat)abstract
- The interfacial structure in “giant” PbS/CdS quantum dots (QDs) was engineered by modulating the Cd:S molar ratio during in situ growth. The control of the gradient interfacial layer could facilitate hole transfer, regulate the transition from double- to single-color emission, as a consequence. These QDs are optically active close-to-the near-infrared (NIR) spectral region and are candidates as absorber materials in solar energy conversion. Photoinduced charge transfer from “giant” QDs to electron scavenger can still take place despite the ultra-thick (~5 nm) shell. The hybrid architecture based on a TiO2 mesoporous framework sensitized by the “giant” QDs with alloyed interface can produce a saturated photocurrent density as high as ~5.3 mA/cm2 in a photoelectrochemical (PEC) cell under 1 Sun illumination, which is around 2 times higher than that of bare PbS and core/thin-shell PbS/CdS QDs sensitizer. The as-prepared PEC device presented very good stability thanks to the “giant” core/shell QDs architecture with tailored interfacial layer and a further coating of the ZnS shell. 78% of the initial current density is kept after 2-hour irradiation at 1 Sun. Engineering of electronic band structure plays a key role in boosting the functional properties of these composite systems, which hold great potential for H2 production in PEC devices.
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| 23. |
- Ju, Ying, et al.
(författare)
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DRL-based Beam Allocation in Relay-aided Multi-user MmWave Vehicular Networks
- 2022
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Ingår i: IEEE INFOCOM 2022 - IEEE CONFERENCE ON COMPUTER COMMUNICATIONS WORKSHOPS (INFOCOM WKSHPS). - : Institute of Electrical and Electronics Engineers (IEEE).
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Konferensbidrag (refereegranskat)abstract
- Millimeter wave (mmWave) communication can realize high transmission rates in vehicular networks. Nevertheless, severe blocking effects and high mobility of vehicles would seriously affect downlink services for vehicles. To ensure communication quality and stability, this paper jointly explores beam allocation and relay selection in mmWave vehicular networks from the perspective of artificial intelligence-driven model. We utilize queuing theory to simulate dynamic distributions of vehicles and firstly propose a deep reinforcement learning (DRL) based joint beam allocation and relay selection scheme to mitigate the blocking effects and optimize the total communication capacity. When the expected downlink is blocked, mmWave base station (mmBS) can select appropriate idle vehicles as the relay nodes for service. Besides, we set the capacity threshold when designing the scheme to guarantee each target vehicle can obtain the ideal service. Through proper training, mmBS can intelligently find an optimal solution for the constantly updated vehicular networks based on the location of vehicles. Simulation results demonstrate the effectiveness of our scheme, which can restrain the transmission outage caused by random blockage and improve the total communication capacity of vehicular networks.
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| 24. |
- Kerrebrouck, Joris Van, et al.
(författare)
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726.7-Gb/s 1.5-μm single-mode VCSEL discrete multi-tone transmission over 2.5-km multicore fiber
- 2018
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Ingår i: 2018 Optical Fiber Communications Conference and Exposition, OFC 2018 - Proceedings. - : Institute of Electrical and Electronics Engineers Inc.. - 9781943580385 ; , s. 1-3
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Konferensbidrag (refereegranskat)abstract
- A 107Gb/s net-rate DMT optical signal was generated using a single-mode long-wavelength VCSEL with a modulation bandwidth of 23 GHz. We experimentally demonstrated a total net-rate up to 726.7Gb/s at 1.5μm over 2.5km 7-core dispersion-uncompensated MCF.
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| 25. |
- Liu, Niantao, et al.
(författare)
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Facile high-voltage sputtering synthesis of three-dimensional hierarchical porous nitrogen-doped carbon coated Si composite for high performance lithium-ion batteries
- 2018
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Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947 .- 1873-3212. ; 343, s. 78-85
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Tidskriftsartikel (refereegranskat)abstract
- Various kinds of efforts have been devoted to ameliorate the serious volume-expansion effect and low electron conductivity of silicon-based materials in lithium ion batteries. Here, we report a facile high voltage sputtering process to prepare three-dimensional hierarchical porous nitrogen-doped carbon coated Si microsphere to significantly improve the lithium storage performance. The structure and morphology of the as-obtained samples are characterized by X-ray diffraction, transmission electron microscope and scanning electron microscope. The results indicate that the as-prepared composite is composed of silicon nanoparticles (similar to 100 nm) coated with conductive thin carbon layer (similar to 8.5 nm). The composite shows excellent lithium storage performance with a reversible capacity of 1565 mAh g(-1) after 100 cycles at a current density of 0.5 A g(-1), as well as a long cycling performance at the high current density of 2 A g(-1). The facile preparation process and highly silicon-loading (similar to 78%) makes the prepared material be a great potential application in lithium-ion batteries.
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| 26. |
- Liu, Tong, PhD Candidate, et al.
(författare)
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A Binary Controller to Ensure Engine Peak Efficiency for a Parallel Hybrid Electric Car
- 2019
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Ingår i: Proceedings 2019 IEEE Intelligent Transportation Systems Conference. - : IEEE. - 9781538670248 ; , s. 726-732
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Konferensbidrag (refereegranskat)abstract
- The fuel efficiency of the hybrid electric vehicle (HEV) highly relies on the engine efficiency. Thispaper proposes a particular powertrain configuration on a small hybrid electric racing car wherethe engine is only allowed to operate withpeak efficiency. An onlinebinarycontroller, accordingly, is developedbased on dynamic programming (DP)to control the engine on/off status and the torques from the electric motors (EMs) to ensure the HEV can successfully complete the drive mission with minimal fuel consumption.For comparison, the paper also develops anoptimal powertrain controller of the same HEV with the normal usage ofthe engine, i.e., the engine operates at any feasible point of the 2Dfuel efficiency map. The simulation results show that this binary controller can improveroughly13% on fuel efficiency compared with the general engine case.
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| 27. |
- Liu, Tong, PhD Candidate, et al.
(författare)
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A Low-Complexity and High-Performance Energy Management Strategy of a Hybrid Electric Vehicle by Model Approximation
- 2022
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Ingår i: 2022 IEEE 18th International Conference on Automation Science and Engineering (CASE). - Mexico City, Mexico : IEEE. ; , s. 455-462
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Konferensbidrag (refereegranskat)abstract
- The fuel economy of a hybrid electric vehicle(HEV) is determined by its energy management strategy (EMS), while the conventional EMS usually suffers from enormous computation loads when solving a nonlinear optimization problem. To resolve this issue, this paper presents a computationally efficient EMS with close-to-optimal performance using very limited computation resources. Relying on the optimal solutions by offline dynamic programming (DP), a constrained model predictive control (MPC) can quickly determine the engine on/off status and then the torque split problem is solved by a value-based Pontryagin’s minimum principle (PMP). Two measures are taken to further reduce the online computation cost: by surface fitting, the tabular value function is replaced by piecewise linear polynomials and thus the memory occupation is greatly reduced; and by model approximation, the nonlinear torque split problem becomes a quadratic programming one that can be more rapidly solved. The testing results from processor-in-the-loop (PIL) simulation indicate that the proposed EMS can generate a fuel efficiency close to the one by DP, but saves 70% onboard memory space and 30% CPU utilization compared with the benchmark EMS without taking the two measures.
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| 28. |
- Liu, Tong, PhD Candidate, 1987-
(författare)
-
Computationally Efficient and Adaptive Energy Management Strategies for Parallel Hybrid Electric Vehicles
- 2023
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Hybrid electric vehicles (HEVs) are irreplaceable in attaining sustainable development in contemporary society. Owing to the extra degree of freedom in supplying traction power, HEVs resort to appropriate energy management strategies (EMSs) to present their superiority over conventional internal combustion engine vehicles and pure electric vehicles.Existing EMSs suffer from heavy computation overheads and excessive mode switches. This thesis proposes several novel methods for developing online EMSs for parallel HEVs that achieve both compelling fuel economy and excellent computation efficiency and adaptivity in online applications with uncertain driving conditions.First, the solutions of offline dynamic programming (DP) are exploited to develop online EMSs for close-to-optimal control performances. The optimal speed profile serves as the reference in online control and the optimal value function (VF) is utilized to design control methods. To avoid the “curse of dimensionality”, the tabular VF is approximated by piecewise polynomials to substantially decrease the computation and memory overheads in online usage.Second, to reduce the search space for optimal control actions, two types of special internal combustion engine (ICE) configurations are adopted and analyzed. The first type forces the ICE to strictly operate at the optimal operation line (OOL), whereas the second one allows a narrow band around the OOL. The second one outperforms the first one because it contributes to more robust ICE operations with slightly higher computation complexity.Third, a hierarchical architecture is proposed for online EMSs so that the transient powertrain mode and torque split scheme are optimized by different methods in sequence. To avoid the exponential complexity of finding the optimal trajectory of the powertrain mode, the optimal VF is leveraged for an optimal decision within one sampling period with the aid of simplified assumptions. Model approximations on the ICE and the electric motor are conducted so as to convert the complex torque split problem into a constrained quadratic programming problem. These methods dramatically facilitate the computation efficiency of online EMSs.Fourth, learning-based adaptive control is introduced to mitigate the adverse effect caused by the deviations between the model and the reality. For this target, efficient learning algorithms are designed to iteratively update the coefficient matrix of the approximated VF. Moreover, to avoid the pitfall of the “cold start” and prompt a fast convergence, the coefficient matrix is initialized by the optimal VF from offline DP.Finally, an event-triggered control mechanism is applied to the torque split control and presents its remarkable advantage in eliminating the excessive computation overheads. At each time step, an efficient trigger algorithm decides if the reference ICE torque is still valid or outdated. If it is valid, the EMS directly uses the reference value as the optimal output; otherwise, the optimization algorithm for torque split control is executed to solve a new value and update the reference.The performances of designed EMSs are tested by processor-in-the-loop simulations so that both the numeric results and the computation efficiency can be obtained for quantitative analysis and comparison. The testing results indicate that the designed EMSs can rapidly adapt to real driving conditions and generate more than 90% fuel economy of the DP optimum, and more importantly, all these EMSs can be implemented on a portable microprocessor with limited onboard computation resources.
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| 29. |
- Liu, Tong, PhD Candidate, et al.
(författare)
-
Computationally Efficient Energy Management for a Hybrid Electric Racing Car by Binary Model Predictive Control and Pontryagin’s Minimum Principle
- 2021
-
Konferensbidrag (refereegranskat)abstract
- To improve the fuel efficiency of a parallel hybrid electric racing car, this paper presents a computationally efficient energy management strategy (EMS) that regulates the internal combustion engine (ICE) to either operate with high efficiency or be switched off. Dynamic programming (DP) is employed to compute the optimal trajectories of vehicle speed and supercapacitor voltage. These trajectories are used as references for real-time online control. The online control contains two parts: a binary model predictive control (B-MPC) that determines the ICE on/off status and a Pontryagin’s minimum principle (PMP) that allocates the total torque demand to fuel and electric paths. The usual challenge to MPC is the large computational complexity and to PMP is the search of optimal costate The proposed EMS evades these two challenges. The binary property of MPC significantly reduces the computational complexity and the optimal costate of PMP is obtained from the value function computed by DP. The testing results by processor-in-the-loop simulation indicate the proposedEMS can realize a close to optimal performance and can be applied on a low-cost microprocessor.
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| 30. |
- Liu, Tong, PhD Candidate, et al.
(författare)
-
Computationally Efficient Energy Management for a Parallel Hybrid Electric Vehicle Using Adaptive Dynamic Programming
-
Tidskriftsartikel (refereegranskat)abstract
- Hybrid electric vehicles (HEVs) rely on energy management strategies (EMSs) to achieve optimal fuel economy. However, both model- and learning-based EMSs have their respective limitations which negatively affect their performances in online applications. This paper presents a computationally efficient adaptive dynamic programming (ADP) approach that can not only rapidly calculate optimal control actions but also iteratively update the approximated value function (AVF) according to the actual fuel and electricity consumption with limited computation resources. Exploiting the AVF, the engine on/off switch and torque split problems are solved by one-step lookahead approximation and Pontryagin’s minimum principle (PMP), respectively. To raise the training speed and reduce the memory space, the tabular value function (VF) is approximated by carefully selected piecewise polynomials via parametric approximation. The advantages of the proposed EMS are threefold and verified by processor-in-the-loop (PIL) Monte Carlo simulations. First, the fuel efficiency of the proposed EMS is higher than that of an adaptive PMP and close to the theoretical optimum. Second, the new method can adapt to the changed driving conditions after a small number of learning iterations and then has higher fuel efficiency than a non-adaptive dynamic programming (DP)controller. Third, the computation efficiencies of the proposed AVF and a tabular VF are compared. The AVF data structure enables faster convergence and saves at least 70% of onboard memory space without obviously increasing the average CPU utilization.
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| 31. |
- Liu, Tong, PhD Candidate, et al.
(författare)
-
Computationally Efficient Energy Management for a Parallel Hybrid Electric Vehicle Using Adaptive Dynamic Programming
- 2024
-
Ingår i: IEEE Transactions on Intelligent Vehicles. - : IEEE. - 2379-8858 .- 2379-8904. ; 9:2, s. 4085-4099
-
Tidskriftsartikel (refereegranskat)abstract
- Hybrid electric vehicles (HEVs) rely on energy management strategies (EMSs) to achieve optimal fuel economy. However, both model- and learning-based EMSs have their respective limitations which negatively affect their performances in online applications. This paper presents a computationally efficient adaptive dynamic programming (ADP) approach that can not only rapidly calculate optimal control actions but also iteratively update the approximated value function (AVF) according to the actual fuel and electricity consumption with limited computation resources. Exploiting the AVF, the engine on/off switch and torque split problems are solved by one-step lookahead approximation and Pontryagin's minimum principle (PMP), respectively. To raise the training speed and reduce the memory space, the tabular value function (VF) is approximated by carefully selected piecewise polynomials via the parametric approximation. The advantages of the proposed EMS are threefold and verified by processor-in-the-loop (PIL) Monte Carlo simulations. First, the fuel efficiency of the proposed EMS is higher than that of an adaptive PMP and close to the theoretical optimum. Second, the new method can adapt to the changed driving conditions after a small number of learning iterations and thus has higher fuel efficiency than a non-adaptive dynamic programming (DP) controller. Third, the computation efficiencies of the proposed AVF and a tabular VF are compared. The concise data structure of the AVF enables faster convergence and saves at least 70% of onboard memory space without obviously increasing the average CPU utilization.
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| 32. |
- Liu, Tong, PhD Candidate, et al.
(författare)
-
Fuel Minimization of a Hybrid Electric Racing Carby Quasi-Pontryagin’s Minimum Principle
- 2021
-
Ingår i: IEEE Transactions on Vehicular Technology. - : IEEE. - 0018-9545 .- 1939-9359.
-
Tidskriftsartikel (refereegranskat)abstract
- This paper improves the fuel efficiency of a student-made parallel hybrid electric racing car whose internal combustion engine (ICE) either operates with peak efficiency or is turned off. The control to the ICE thus becomes a binary problem. Owing to the very limited computation resource onboard, the energy management strategy (EMS) for this car must have small time and space complexities. A computationally efficient controller that combines the advantages of dynamic programming (DP) and Pontryagins minimum principle (PMP) is developed to run on a low-cost microprocessor. DP is employed offline to calculate the optimal speed trajectory, which is used as the reference for the online PMP to determine the real-time ICE on/off status and the electric motor (EM) torques. The normal PMP derives the optimal costate trajectory through solving partial differential equations. The proposed quasi-PMP (Q-PMP) method finds the costate from the value function obtained by DP. The fuel efficiency and computational complexity of the proposed controller are compared against several state of art methods through both model-in-the-loop (MIL) and processor-in-the-loop (PIL) simulations. The new method reaches similar fuel efficiency as the explicit DP, but requires less than 1% onboard flash memory. The performance of the Q-PMP controller is compared between binary-controlled and continuously controlled engines. It achieves roughly 12% higher fuel efficiency for the binary engine with only approximately 1/3 CPU utilization.
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| 33. |
- Liu, Tong, PhD Candidate, et al.
(författare)
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Increasing Fuel Efficiency of a Hybrid Electric Competition Car by a Binary Equivalent Consumption Minimization Strategy
- 2018
-
Ingår i: 2018 IEEE 14th International Conference on Automation Science and Engineering (CASE). - : IEEE. - 9781538635933
-
Konferensbidrag (refereegranskat)abstract
- To improve the fuel efficiency of a hybrid electric car with special powertrain features racing in Shell Eco-marathon, a computationally efficient online control system is developed by solving hierarchical optimal control problems. The top-level computes the optimal velocity trajectory based on the given competition track in advance. The lower-level then finds the best instantaneous engine state and torque allocation by the equivalent consumption minimization strategy (ECMS). The special design of the competition car reduces the ECMS into a binary optimization problem. The new controller can run in real-time on low-cost microprocessors and improves the car's fuel efficiency by 50% while maintaining the state of charge of the electrical energy buffer.
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| 34. |
- Liu, Tong, PhD Candidate, et al.
(författare)
-
Optimal and Adaptive Engine Switch Control for a Parallel Hybrid Electric Vehicle Using a Computationally Efficient Actor-Critic Method
- 2023
-
Ingår i: IEEE/ASME International Conference on Advanced Intelligent Mechatronics, AIM. - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 416-423
-
Konferensbidrag (refereegranskat)abstract
- Energy management strategies (EMSs) are crucial to the fuel economy of hybrid electric vehicles (HEVs). However, due to the lack of efficient solving approaches, most of existing EMSs mainly focus on the optimal torque split between the internal combustion engine (ICE) and the electric motor but neglect improper ICE on/off switches, and thus usually suffer degraded fuel economy and even unacceptable drivability in practice. To tackle this issue, this paper presents a novel EMS that uses an efficient actor-critic (AC) method to regulate ICE switches with limited computation resources. While common AC methods use complex neural networks (NNs) with arbitrary initialization, the proposed AC uses piecewise cubic polynomials whose parameters are initialized based on optimized solutions of dynamic programming (DP). By this means, the AC can quickly converge with high computation efficiency. The testing results from processor-in-the-loop (PIL) simulations showcase that, compared with a rule-based EMS with tabular value functions, the proposed EMS can greatly improve the equivalent fuel economy by eliminating improper ICE switches after only several iterations of adaptive learning and dramatically save onboard memory space owing to the concise AC structure.
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| 35. |
- Liu, Zhigang, et al.
(författare)
-
Gut microbiota mediates intermittent-fasting alleviation of diabetes-induced cognitive impairment
- 2020
-
Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723 .- 2041-1723. ; 11:1, s. 855-
-
Tidskriftsartikel (refereegranskat)abstract
- Cognitive decline is one of the complications of type 2 diabetes (T2D). Intermittent fasting (IF) is a promising dietary intervention for alleviating T2D symptoms, but its protective effect on diabetes-driven cognitive dysfunction remains elusive. Here, we find that a 28-day IF regimen for diabetic mice improves behavioral impairment via a microbiota-metabolites-brain axis: IF enhances mitochondrial biogenesis and energy metabolism gene expression in hippocampus, re-structures the gut microbiota, and improves microbial metabolites that are related to cognitive function. Moreover, strong connections are observed between IF affected genes, microbiota and metabolites, as assessed by integrative modelling. Removing gut microbiota with antibiotics partly abolishes the neuroprotective effects of IF. Administration of 3-indolepropionic acid, serotonin, short chain fatty acids or tauroursodeoxycholic acid shows a similar effect to IF in terms of improving cognitive function. Together, our study purports the microbiota-metabolites-brain axis as a mechanism that can enable therapeutic strategies against metabolism-implicated cognitive pathophysiologies.
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| 36. |
- Peng, Xuerun, et al.
(författare)
-
Emetine, a small molecule natural product, displays potent anti-gastric cancer activity via regulation of multiple signaling pathways
- 2023
-
Ingår i: Cancer Chemotherapy and Pharmacology. - : Springer. - 0344-5704 .- 1432-0843. ; 91:4, s. 303-315
-
Tidskriftsartikel (refereegranskat)abstract
- Background Gastric cancer (GC) is a life-threatening malignant tumor with high incidence rate. Despite great progress, there are still many GC sufferers that cannot benefit from the existing anti-GC treatments. Therefore, it is still necessary to develop novel medicines against GC. Emetine, a natural small molecule isolated from Psychotria ipecacuanha, has been broadly used for medicinal purposes including cancer treatment. Here, we conducted a comprehensive study on the anti-GC effects of emetine and the related mechanisms of action.Methods The cell viability was evaluated by MTT and colony formation assay. Cellular proliferation and apoptosis were analyzed by edu incorporation assay and Annexin V-PI staining, respectively. Moreover, wound healing assay and transwell invasion assay were conducted to detect cell migration and invasion after treatment with emetine. To elucidate the molecular mechanism involved in the anti-GC effects of emetine, RNA sequencing and functional enrichment analysis were carried out on MGC803 cells. Then, the western blot analysis was performed to further verify the anti-GC mechanism of emetine. In vivo anti-tumor efficacy of emetine was evaluated in the MGC803 xenograft model.Results MTT and colony formation assay exhibited a strong potency of emetine against GC cell growth, with IC50 values of 0.0497 μM and 0.0244 μM on MGC803 and HGC-27 cells, respectively. Further pharmacodynamic studies revealed that emetine restrained the growth of GC cells mainly via proliferation inhibition and apoptosis induction. Meanwhile, emetine also had the ability to block GC cell migration and invasion. The results of RNA sequencing and western blot showed that emetine acted through regulating multiple signaling pathways, including not only MAPKs and Wnt/β-catenin signaling axes, but also PI3K/AKT and Hippo/YAP signaling cascades that were not found in other tumor types. Notably, the antitumor efficacy of emetine could also be observed in MGC803 xenograft models.Conclusion Our data demonstrate that emetine is a promising lead compound and even a potential drug candidate for GC treatment, deserving further structural optimization and development.
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| 37. |
- Ruilope, LM, et al.
(författare)
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Design and Baseline Characteristics of the Finerenone in Reducing Cardiovascular Mortality and Morbidity in Diabetic Kidney Disease Trial
- 2019
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Ingår i: American journal of nephrology. - : S. Karger AG. - 1421-9670 .- 0250-8095. ; 50:5, s. 345-356
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Tidskriftsartikel (refereegranskat)abstract
- <b><i>Background:</i></b> Among people with diabetes, those with kidney disease have exceptionally high rates of cardiovascular (CV) morbidity and mortality and progression of their underlying kidney disease. Finerenone is a novel, nonsteroidal, selective mineralocorticoid receptor antagonist that has shown to reduce albuminuria in type 2 diabetes (T2D) patients with chronic kidney disease (CKD) while revealing only a low risk of hyperkalemia. However, the effect of finerenone on CV and renal outcomes has not yet been investigated in long-term trials. <b><i>Patients and</i></b> <b><i>Methods:</i></b> The Finerenone in Reducing CV Mortality and Morbidity in Diabetic Kidney Disease (FIGARO-DKD) trial aims to assess the efficacy and safety of finerenone compared to placebo at reducing clinically important CV and renal outcomes in T2D patients with CKD. FIGARO-DKD is a randomized, double-blind, placebo-controlled, parallel-group, event-driven trial running in 47 countries with an expected duration of approximately 6 years. FIGARO-DKD randomized 7,437 patients with an estimated glomerular filtration rate ≥25 mL/min/1.73 m<sup>2</sup> and albuminuria (urinary albumin-to-creatinine ratio ≥30 to ≤5,000 mg/g). The study has at least 90% power to detect a 20% reduction in the risk of the primary outcome (overall two-sided significance level α = 0.05), the composite of time to first occurrence of CV death, nonfatal myocardial infarction, nonfatal stroke, or hospitalization for heart failure. <b><i>Conclusions:</i></b> FIGARO-DKD will determine whether an optimally treated cohort of T2D patients with CKD at high risk of CV and renal events will experience cardiorenal benefits with the addition of finerenone to their treatment regimen. Trial Registration: EudraCT number: 2015-000950-39; ClinicalTrials.gov identifier: NCT02545049.
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| 38. |
- Staehle, Robert, et al.
(författare)
-
Water oxidation catalyzed by mononuclear ruthenium complexes with a 2,2′-bipyridine-6,6′-dicarboxylate (bda) ligand : How ligand environment influences the catalytic behavior
- 2014
-
Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 53:3, s. 1307-1319
-
Tidskriftsartikel (refereegranskat)abstract
- A new water oxidation catalyst [RuIII(bda)(mmi)(OH 2)](CF3SO3) (2, H2bda = 2,2′-bipyridine-6,6′-dicarboxylic acid; mmi = 1,3- dimethylimidazolium-2-ylidene) containing an axial N-heterocyclic carbene ligand and one aqua ligand was synthesized and fully characterized. The kinetics of catalytic water oxidation by 2 were measured using stopped-flow technique, and key intermediates in the catalytic cycle were probed by density functional theory calculations. While analogous Ru-bda water oxidation catalysts [Ru(bda)L2] (L = pyridyl ligands) are supposed to catalyze water oxidation through a bimolecular coupling pathway, our study points out that 2, surprisingly, undergoes a single-site water nucleophilic attack (acid-base) pathway. The diversion of catalytic mechanisms is mainly ascribed to the different ligand environments, from nonaqua ligands to an aqua ligand. Findings in this work provide some critical proof for our previous hypothesis about how alternation of ancillary ligands of water oxidation catalysts influences their catalytic efficiency.
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| 39. |
- Tang, Fei, et al.
(författare)
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Study of the smoke toxicity characteristics in an inclined tunnel
- 2024
-
Ingår i: Fire Safety Journal. - 0379-7112. ; 142
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Tidskriftsartikel (refereegranskat)abstract
- Fire smoke is one of the most important factors causing casualties, but also has the potential to bring some harm to the surrounding environment. In this work, the longitudinal temperature profile and the pollutant toxicity of a ceiling jet induced by a wall-attached fire with different tunnel slopes, were numerically and experimentally investigated by using a 1:8 reduced-scale inclined tunnel. The results show that for a given heat release rate (HRR), the flame extension is longer and the temperature decay is slower in ceiling jets induced by a wall-attached fire than for similar free-burning fires, because the air entrainment is restricted by the tunnel side walls. Further, the uphill pollutant toxicity was found to be higher with greater HRR and lower tunnel slope. Finally, a correlation between the non-dimensional longitudinal smoke temperature and CO concentration could be established for the inclined tunnel fire.
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| 40. |
- Tong, Kangkang, et al.
(författare)
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Greenhouse gas emissions from key infrastructure sectors in larger and smaller Chinese cities: method development and benchmarking
- 2016
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Ingår i: Carbon Management. - : Informa UK Limited. - 1758-3012 .- 1758-3004. ; 7:1-2, s. 27-39
-
Tidskriftsartikel (refereegranskat)abstract
- With massive urbanization and infrastructure investments occurring in China, understanding GHG emissions from infrastructure use in small and large Chinese cities with different administrative levels is important for building future low-carbon cities. This paper identifies diverse data sources to assess GHG emission from community-wide infrastructure footprints (CIF) in four Chinese cities of varying population (1 to 20 million people) and administrative levels: Yixing, Qinhuangdao, Xiamen and Beijing. CIF addresses seven infrastructure sectors providing energy (fuels/coal), electricity, water supply and wastewater treatment, transportation, municipal waste management, construction materials, and food to support urban activities. Industrial energy use dominates the infrastructure GHG CIF in all four cities, ranging from 76% of total CIF in Yixing to 30% in Beijing, followed by residential energy use (6–13%), transportation (4–12%), commercial energy use (2–25%), food (6–11%), cement use (3–8%) and water (about 1%), thereby identifying priorities for low-carbon infrastructure development. Trans-boundary footprint contributions ranged from 31% (Beijing) to 8% (Qinhuangdao), indicating that supply chains to cities are important. GHGs from energy use are dominated by electricity (35–45%) and non-electricity coal use (30–50%). The authors demonstrate that disaggregated infrastructure use-efficiency metrics in each infrastructure sector provide useful baseline performance data for comparing diverse cities.
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| 41. |
- Tong, Lianpeng, et al.
(författare)
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Catalytic Water Oxidation by Mononuclear Ru Complexes with an Anionic Ancillary Ligand
- 2013
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 52:5, s. 2505-2518
-
Tidskriftsartikel (refereegranskat)abstract
- Mononuclear Ru-based water oxidation catalysts containing anionic ancillary ligands have shown promising catalytic efficiency and intriguing properties. However, their insolubility in water restricts a detailed mechanism investigation. In order to overcome this disadvantage, complexes [Ru-II(bpc)(bpy)OH2](+) (1(+), bpc = 2,2'-bipyridine-6-carboxylate, bpy = 2,2'-bipyridine) and [Ru-II(bpc)(pic)(3)](+) (2(+), pic = 4-picoline) were prepared and fully characterized, which features an anionic tridentate ligand and has enough solubility for spectroscopic study in water. Using Ce-IV as an electron acceptor, both complexes are able to catalyze O-2-evolving reaction with an impressive rate constant. On the basis of the electrochemical and kinetic studies, a water nucleophilic attack pathway was proposed as the dominant catalytic cycle of the catalytic water oxidation by 1(+), within which several intermediates were detected by MS. Meanwhile, an auxiliary pathway that is related to the concentration of Ce-IV was also revealed. The effect of anionic ligand regarding catalytic water oxidation was discussed explicitly in comparison with previously reported mononuclear Ru catalysts carrying neutral tridentate ligands, for example, 2,2':6',2 ''-terpyridine (tpy). When 2(+) was oxidized to the trivalent state, one of its picoline ligands dissociated from the Ru center. The rate constant of picoline dissociation was evaluated from time-resolved UV-vis spectra.
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| 42. |
- Tong, Xin, et al.
(författare)
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Heavy Metal-free, Near-infrared Colloidal Quantum Dots for Efficient Photoelectrochemical Hydrogen Generation
- 2017
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Ingår i: Nano Energy. - : Elsevier. - 2211-2855. ; 31, s. 441-449
-
Tidskriftsartikel (refereegranskat)abstract
- Photoelectrochemical (PEC) hydrogen generation based on colloidal quantum dots (QDs) is very promising because of its high solar energy to fuel conversion efficiency and low fabrication costs. However, its commercial development is hindered by various challenges, including the widespread use of toxic heavy metal–based QDs as sensitizers. We report an environmentally friendly, high efficiency PEC device in which the photoanode consists of a mesoporous TiO2 film sensitized with heavy metal-free, near-infrared (NIR) colloidal CuInSexS2-x (CISeS) QDs. To reduce surface-related traps, we grew an ultrathin ZnS shell on the CISeS core QDs by cation exchange. The PEC cell based on this core/shell CISeS/ZnS QDs exhibits suppressed charge recombination and a saturated photocurrent density of ~5.3 mA/cm2 under one sun illumination (AM 1.5 G, 100 mW/cm2). In addition, the as-prepared PEC device shows an outstanding stability, exhibiting a drop of only 23% after 9 h illumination. The success in using such core/shell CISeS/ZnS QDs paves the way to realize environment-friendly, high efficiency and cost-effective PEC devices for hydrogen production.
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| 43. |
- Tong, Yang, et al.
(författare)
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Progress of the key materials for organic solar cells
- 2020
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Ingår i: Science in China Series B. - Beijing, China : SCIENCE PRESS. - 1674-7291 .- 1869-1870. ; 63:6, s. 758-765
-
Forskningsöversikt (refereegranskat)abstract
- Organic solar cells have attracted academic and industrial interests due to the advantages like lightweight, flexibility and roll-to-roll fabrication. Nowadays, 18% power conversion efficiency has been achieved in the state-of-the-art organic solar cells. The recent rapid progress in organic solar cells relies on the continuously emerging new materials and device fabrication technologies, and the deep understanding on film morphology, molecular packing and device physics. Donor and acceptor materials are the key materials for organic solar cells since they determine the device performance. The past 25 years have witnessed an odyssey in developing high-performance donors and acceptors. In this review, we focus on those star materials and milestone work, and introduce the molecular structure evolution of key materials. These key materials include homopolymer donors, D-A copolymer donors, A-D-A small molecular donors, fullerene acceptors and nonfullerene acceptors. At last, we outlook the challenges and very important directions in key materials development.
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| 44. |
- Tu, Yongming, et al.
(författare)
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Shock-induced reactive molecular dynamics simulation in sodium aluminosilicate hydrate: Wave propagation, mechanical response, and structural deformation
- 2023
-
Ingår i: Journal of Non-Crystalline Solids. - : Elsevier B.V.. - 0022-3093 .- 1873-4812. ; 612
-
Tidskriftsartikel (refereegranskat)abstract
- Sodium aluminosilicate hydrate (N-A-S-H) gels have gained attention due to their potential use as components of geopolymers to improve structural and mechanical properties. In this study, we investigated the propagation of shock waves in N-A-S-H gels subjected to impact velocities (Up) ranging from 0.1 to 3.0 km/s, as well as the resulting mechanical responses and structural deformations. Our results showed that when Up<0.4 km/s, only one elastic wave existed, and the Hugoniot elastic limit was estimated to be 4.1 GPa. Above this limit, a two-wave structure formed. The elastic and elastoplastic deformation mechanisms involved initial compaction and densification of the N-A-S-H gel structure, followed by bond angle bending. The Hugoniot Us-Up relationship was found to be linear in the elastoplastic region, with a linear parameter λ of approximately 2.75. These new atomistic insights into the shock compression of N-A-S-H gels will provide valuable guidance for future studies.
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| 45. |
- Wang, Lei, et al.
(författare)
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Visible light-driven water oxidation catalyzed by mononuclear ruthenium complexes
- 2013
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Ingår i: Journal of Catalysis. - : Elsevier BV. - 0021-9517 .- 1090-2694. ; 306, s. 129-132
-
Tidskriftsartikel (refereegranskat)abstract
- A series of mononuclear ruthenium water oxidation catalysts (WOCs) [Ru(bda)L-2] (H(2)bda = 2,2'-bipyridine-6,6'-dicarboxylic acid; L = N-cyclic aromatic ligands) were investigated in three-component light-driven water oxidation systems composed of photosensitizers, a sacrificial electron acceptor, and WOCs. A high turnover number of 579 for water oxidation was achieved in the homogeneous system using complex 4 ([Ru(bda)(4-Br-pyridine)(2)]) as the WOC, and a high quantum efficiency of 17% was found which is a new record for visible light-driven water oxidation in homogeneous systems.
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| 46. |
- Wang, Rongrong, et al.
(författare)
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Cross-cultural adaptation of Life Satisfaction Checklist-11 among persons with stroke in China : A reliability and validity study
- 2021
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Ingår i: Physiotherapy Research International. - : John Wiley & Sons. - 1358-2267 .- 1471-2865. ; 26:2
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: The aim of the present study was to develop a cross-cultural adaptation and to evaluate the validity and reliability of a Chinese version of the LiSat-11 test.Methods: LiSat-11 was translated into Chinese according to standardized procedures. A cross-sectional descriptive study was conducted to examine its reliability and validity, in accordance to COnsensus-based Standards for the election of health Measurements Instruments guidelines, among persons with stroke approximately 3 years after their discharge from rehabilitation. Participants completed the LiSat-11, 36-Item Short-Form Health Survey (SF-36), National Institutes of Health Stroke Scale (NIHSS), modified Rankin Scale (mRS), Barthel Index (BI) and Hospital Anxiety and Depression Scale (HADS). To examine the test-retest reliability, thirty of these participants completed LiSat-11 again after 2 weeks.Results: In total, 60 persons with stroke were recruited. The Chinese version of LiSat-11 demonstrated good internal consistency with Cronbach's alphas at 0.82. Ceiling effects were found in five of the eleven items of LiSat-11, and there was a floor effect in one item. LiSat-11 had moderate to high correlations with SF-36 with Spearman's correlation coefficient (rho) ranging from 0.44 to 0.73 (p < 0.01) in a concurrent validity test, and high correlations were also found between LiSat-11 and HADS-A/D in a convergent validity test with rho = -0.63/-0.67 (p < 0.01). Low correlations with NIHSS, BI and mRS were found in a divergent validity test, rho = -0.25, 0.17 and -0.26, respectively.Conclusion: The current study verified that the translated Chinese version of the Life Satisfaction Checklist-11 is a reliable and valid tool for measuring the life satisfaction of persons with chronic stroke.
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| 47. |
- Wang, Tongfang, et al.
(författare)
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Molecular dynamics study on structural characteristics and mechanical properties of sodium aluminosilicate hydrate with immobilized radioactive Cs and Sr ions
- 2023
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Ingår i: Applied Clay Science. - : Elsevier Ltd. - 0169-1317 .- 1872-9053. ; 243
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Tidskriftsartikel (refereegranskat)abstract
- As a low-carbon, environment-friendly and economical resource for nuclear power generation, radionuclide emission and storage has received worldwide attention. Geopolymer concrete is a green and sustainable building material that can be used to immobilize radionuclides. In the present study, molecular dynamics simulations were conducted to investigate the structural and mechanical properties of sodium aluminosilicate hydrate (NASH) gel, the main component of geopolymer concrete, with/without immobilized radioactive Cs and Sr ions. The three-dimensional structure of NASH gel enabled good immobilization of both radioactive Cs and Sr ions owing to the large radius of Cs ions and high charge density of Sr ions. Addition of Cs ions reduced the strength of the gel and increased the fracture strain, whereas addition of Sr ions increased the strength and significantly increased the ductility. Addition of Sr ions increased the number of penta-coordinated Al in the structure. Consequently, breakage of these bonds required more energy to be absorbed from outside. The nanoscale molecular dynamics simulations provided a theoretical support at atomic level for understanding the structural and mechanical characteristics of geopolymers pertinent to the immobilization of nuclear waste.
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| 48. |
- Wang, Xin, et al.
(författare)
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Organic nanocrystals induced surface passivation towards high-efficiency and stable perovskite solar cells
- 2021
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Ingår i: Nano Energy. - : ELSEVIER. - 2211-2855 .- 2211-3282. ; 89
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Tidskriftsartikel (refereegranskat)abstract
- Surface passivation has played a critical role for efficient and stable perovskite solar cells by reducing surface defects, promoting charge transport, and preventing the penetration of degrading agents. State-of-the-art passivation approaches mainly rely on the formation of a two-dimensional (2D) perovskite layer or the deposition of an ultrathin layer based on the molecular design. Here, we demonstrated a novel nanocrystal-pinning passivation by dripping 2-bromoethyltrimethylammonium bromide (BETAB) colloidal solution onto perovskite films. Theoretical simulation and kinds of experimental results confirm that BETAB nanocrystals can effectively reduce the defect density of perovskite films. Impressively, the resulting FA1-xMAxPbI3 based planar devices exhibit a champion power conversion efficiency (PCE) of 23.04% (certified: 22.10%) with a voltage loss of only 390 mV. Besides, the BETAB nanocrystals could simultaneously increase the hydrophobic property of perovskite films and prevent the reaction and formation of 2D perovskites during device operation. Correspondingly, the resulted devices exhibit excellent stability under moisture, heating, and operational tracking conditions.
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| 49. |
- Wang, Yu-Cheng, et al.
(författare)
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Porous Carbon Membrane-Supported Atomically Dispersed Pyrrole-Type Fe-N-4 as Active Sites for Electrochemical Hydrazine Oxidation Reaction
- 2020
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Ingår i: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 16:31
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Tidskriftsartikel (refereegranskat)abstract
- The rational design of catalytically active sites in porous materials is essential in electrocatalysis. Herein, atomically dispersed Fe-N-x sites supported by hierarchically porous carbon membranes are designed to electrocatalyze the hydrazine oxidation reaction (HzOR), one of the key techniques in electrochemical nitrogen transformation. The high intrinsic catalytic activity of the Fe-N-x single-atom catalyst together with the uniquely mixed micro-/macroporous membrane support positions such an electrode among the best-known heteroatom-based carbon anodes for hydrazine fuel cells. Combined with advanced characterization techniques, electrochemical probe experiments, and density functional theory calculation, the pyrrole-type Fe-N-4 structure is identified as the real catalytic site in HzOR.
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| 50. |
- Wen, Rongjia, et al.
(författare)
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Effects of temperature on ion transport in C–A–S–H gel nanopores: insights from molecular dynamics simulations
- 2022
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Ingår i: Journal of Materials Science. - : Springer Nature. - 0022-2461 .- 1573-4803. ; 57:39, s. 18437-18455
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, molecular dynamics simulations are used to study the effects of temperature on the transport of chloride and sulfate in the nanopores of aluminum-doped cement-based materials (i.e., CASH gels) exposed to aqueous solutions of NaCl and Na2SO4 at 283, 293, 303, 333, and 363 K. It is shown that high temperatures increase the initial transport rates of water molecules and ions while weakening the hydration layer around ions. This increases the probability of ion–ion and ion–substrate contact and thus makes ions more likely to cluster in solution and be captured by the substrate. Both cluster formation and substrate capture can significantly restrict the free movement of ions in solution and thus gradually reduce the ion transport rate. In addition, since sulfate ions have four oxygen atoms that can capture other ions, large ion clusters form more readily in Na2SO4 solution than in NaCl solution. The capture of these large ion clusters at the interface can cause a “necking” phenomenon that hinders the subsequent transport of water molecules and ions into the nanopore. These results provide a nanoscale basis for designing aluminum-doped cement-based materials with enhanced durability at high temperatures.
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