| 1. |
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| 2. |
- Kristanl, Matej, et al.
(author)
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The Seventh Visual Object Tracking VOT2019 Challenge Results
- 2019
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In: 2019 IEEE/CVF INTERNATIONAL CONFERENCE ON COMPUTER VISION WORKSHOPS (ICCVW). - : IEEE COMPUTER SOC. - 9781728150239 ; , s. 2206-2241
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Conference paper (peer-reviewed)abstract
- The Visual Object Tracking challenge VOT2019 is the seventh annual tracker benchmarking activity organized by the VOT initiative. Results of 81 trackers are presented; many are state-of-the-art trackers published at major computer vision conferences or in journals in the recent years. The evaluation included the standard VOT and other popular methodologies for short-term tracking analysis as well as the standard VOT methodology for long-term tracking analysis. The VOT2019 challenge was composed of five challenges focusing on different tracking domains: (i) VOT-ST2019 challenge focused on short-term tracking in RGB, (ii) VOT-RT2019 challenge focused on "real-time" short-term tracking in RGB, (iii) VOT-LT2019 focused on long-term tracking namely coping with target disappearance and reappearance. Two new challenges have been introduced: (iv) VOT-RGBT2019 challenge focused on short-term tracking in RGB and thermal imagery and (v) VOT-RGBD2019 challenge focused on long-term tracking in RGB and depth imagery. The VOT-ST2019, VOT-RT2019 and VOT-LT2019 datasets were refreshed while new datasets were introduced for VOT-RGBT2019 and VOT-RGBD2019. The VOT toolkit has been updated to support both standard short-term, long-term tracking and tracking with multi-channel imagery. Performance of the tested trackers typically by far exceeds standard baselines. The source code for most of the trackers is publicly available from the VOT page. The dataset, the evaluation kit and the results are publicly available at the challenge website(1).
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| 3. |
- Chen, Geng, et al.
(author)
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Experimental Test of the State Estimation-Reversal Tradeoff Relation in General Quantum Measurements
- 2014
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In: Physical Review X. - 2160-3308. ; 4:5, s. 021043-
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Journal article (peer-reviewed)abstract
- When a measurement has limited strength, only partial information, regarding the initial state, is extracted, and, correspondingly, there is a probability to reverse its effect on the system and retrieve the original state. Recently, a clear and direct quantitative description of this complementary relationship, in terms of a tradeoff relation, was developed by Y. K. Cheong and S. W. Lee. [Phys. Rev. Lett. 109, 150402 (2012)]. Here, this tradeoff relation is experimentally verified using polarization-encoded single photons from a quantum dot. Measurement operators representing a complete range, from not affecting the system to a projection to a single polarization state, are realized. In addition, for each measurement operator, an optimal reversal operator is also implemented. The upper bound of the tradeoff relation is mapped to experimental parameters representing the measurement strength. Our results complement the theoretical work and provide a hands-on characterization of general quantum measurements.
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| 4. |
- Luo, Yifei, et al.
(author)
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Technology Roadmap for Flexible Sensors
- 2023
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In: ACS Nano. - : American Chemical Society. - 1936-0851 .- 1936-086X. ; 17:6, s. 5211-5295
-
Research review (peer-reviewed)abstract
- Humans rely increasingly on sensors to address grand challenges and to improve quality of life in the era of digitalization and big data. For ubiquitous sensing, flexible sensors are developed to overcome the limitations of conventional rigid counterparts. Despite rapid advancement in bench-side research over the last decade, the market adoption of flexible sensors remains limited. To ease and to expedite their deployment, here, we identify bottlenecks hindering the maturation of flexible sensors and propose promising solutions. We first analyze challenges in achieving satisfactory sensing performance for real-world applications and then summarize issues in compatible sensor-biology interfaces, followed by brief discussions on powering and connecting sensor networks. Issues en route to commercialization and for sustainable growth of the sector are also analyzed, highlighting environmental concerns and emphasizing nontechnical issues such as business, regulatory, and ethical considerations. Additionally, we look at future intelligent flexible sensors. In proposing a comprehensive roadmap, we hope to steer research efforts towards common goals and to guide coordinated development strategies from disparate communities. Through such collaborative efforts, scientific breakthroughs can be made sooner and capitalized for the betterment of humanity.
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| 5. |
- Pan, Wei-Wei, et al.
(author)
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Direct Measurement of a Nonlocal Entangled Quantum State
- 2019
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 123:15
-
Journal article (peer-reviewed)abstract
- Entanglement and the wave function description are two of the core concepts that make quantum mechanics such a unique theory. A method to directly measure the wave function, using weak values, was demonstrated by Lundeen et al. [Nature 474, 188 (2011)]. However, it is not applicable to a scenario of two disjoint systems, where nonlocal entanglement can be a crucial element, since that requires obtaining weak values of nonlocal observables. Here, for the first time, we propose a method to directly measure a nonlocal wave function of a bipartite system, using modular values. The method is experimentally implemented for a photon pair in a hyperentangled state, i.e., entangled both in polarization and momentum degrees of freedom.
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| 6. |
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| 7. |
- Sikkema, Lisa, et al.
(author)
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An integrated cell atlas of the lung in health and disease
- 2023
-
In: Nature Medicine. - : Springer Nature. - 1078-8956 .- 1546-170X. ; 29:6, s. 1563-1577
-
Journal article (peer-reviewed)abstract
- Single-cell technologies have transformed our understanding of human tissues. Yet, studies typically capture only a limited number of donors and disagree on cell type definitions. Integrating many single-cell datasets can address these limitations of individual studies and capture the variability present in the population. Here we present the integrated Human Lung Cell Atlas (HLCA), combining 49 datasets of the human respiratory system into a single atlas spanning over 2.4 million cells from 486 individuals. The HLCA presents a consensus cell type re-annotation with matching marker genes, including annotations of rare and previously undescribed cell types. Leveraging the number and diversity of individuals in the HLCA, we identify gene modules that are associated with demographic covariates such as age, sex and body mass index, as well as gene modules changing expression along the proximal-to-distal axis of the bronchial tree. Mapping new data to the HLCA enables rapid data annotation and interpretation. Using the HLCA as a reference for the study of disease, we identify shared cell states across multiple lung diseases, including SPP1 + profibrotic monocyte-derived macrophages in COVID-19, pulmonary fibrosis and lung carcinoma. Overall, the HLCA serves as an example for the development and use of large-scale, cross-dataset organ atlases within the Human Cell Atlas.
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| 8. |
- Xu, Xiao-Ye, et al.
(author)
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Experimental extraction of nonlocal weak values for demonstrating the failure of a product rule
- 2020
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In: Optics Letters. - 0146-9592 .- 1539-4794. ; 45:7, s. 1715-1718
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Journal article (peer-reviewed)abstract
- We experimentally demonstrate an alternative method for measuring nonlocal weak values in linear optics, avoiding the use of second-order interaction. The method is based on the concept of modular values. The paths of two photons, initialized in hyperentangled states, are adopted as the meter with the polarization acting as the system. The modular values are read out through the reconstructed final states of the meter. The weak value of nonlocal observables is given through its connection to the modular value. Comparing the weak values of local and nonlocal observables, we demonstrate the failure of product rules for an entangled system. Our results significantly simplify the task of measuring nonloral weak values and will play an important role in the application of weak measurement.
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| 9. |
- Xu, Xiao-Ye, et al.
(author)
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Measurements of Nonlocal Variables and Demonstration of the Failure of the Product Rule for a Pre- and Postselected Pair of Photons
- 2019
-
In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 122:10
-
Journal article (peer-reviewed)abstract
- We report the first implementation of the von Neumann instantaneous measurements of nonlocal variables, which becomes possible due to technological achievements in creating hyperentangled photons. Tests of reliability and of the nondemolition property of the measurements have been performed with high precision, showing the suitability of the scheme as a basic ingredient of numerous quantum information protocols. The method allows us to demonstrate for the first time with strong measurements a special feature of pre- and postselected quantum systems: the failure of the product rule. It has been verified experimentally that for a particular pre- and postselected pair of particles, a single measurement on particle A yields with certainty sigma(A)(x) = -1, a single measurement on particle B yields with certainty sigma(B)(y) = -1, and a single nonlocal measurement on particles A and B yields with certainty sigma(A)(x) sigma(B)(y) = -1.
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| 10. |
- Zhou, Ke, et al.
(author)
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pi-pi Stacking Distance and Phase Separation Controlled Efficiency in Stable All-Polymer Solar Cells
- 2019
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In: Polymers. - : MDPI. - 2073-4360. ; 11:10
-
Journal article (peer-reviewed)abstract
- The morphology of the active layer plays a crucial role in determining device performance and stability for organic solar cells. All-polymer solar cells (All-PSCs), showing robust and stable morphologies, have been proven to give better thermal stability than their fullerene counterparts. However, outstanding thermal stability is not always the case for polymer blends, and the limiting factors responsible for the poor thermal stability in some All-PSCs, and how to obtain higher efficiency without losing stability, still remain unclear. By studying the morphology of poly [2,3-bis (3-octyloxyphenyl) quinoxaline-5,8-diyl-alt-thiophene-2,5-diyl](TQ1)/poly[4,8-bis[5-(2-ethylhexyl)-2-thienyl]benzo[1,2-b:4,5-b ]dithiophene-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl]] (PCE10)/PNDI-T10 blend systems, we found that the rearranged molecular packing structure and phase separation were mainly responsible for the poor thermal stability in devices containing PCE10. The TQ1/PNDI-T10 devices exhibited an improved PCE with a decreased pi-pi stacking distance after thermal annealing; PCE10/PNDI-T10 devices showed a better pristine PCE, however, thermal annealing induced the increased pi-pi stacking distance and thus inferior hole conductivity, leading to a decreased PCE. Thus, a maximum PCE could be achieved in a TQ1/PCE10/PNDI-T10 (1/1/1) ternary system after thermal annealing resulting from their favorable molecular interaction and the trade-off of molecular packing structure variations between TQ1 and PCE10. This indicates that a route to efficient and thermal stable All-PSCs can be achieved in a ternary blend by using material with excellent pristine efficiency, combined with another material showing improved efficiency under thermal annealing.
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| 11. |
- Botvinik-Nezer, Rotem, et al.
(author)
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Variability in the analysis of a single neuroimaging dataset by many teams
- 2020
-
In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 582, s. 84-88
-
Journal article (peer-reviewed)abstract
- Data analysis workflows in many scientific domains have become increasingly complex and flexible. Here we assess the effect of this flexibility on the results of functional magnetic resonance imaging by asking 70 independent teams to analyse the same dataset, testing the same 9 ex-ante hypotheses(1). The flexibility of analytical approaches is exemplified by the fact that no two teams chose identical workflows to analyse the data. This flexibility resulted in sizeable variation in the results of hypothesis tests, even for teams whose statistical maps were highly correlated at intermediate stages of the analysis pipeline. Variation in reported results was related to several aspects of analysis methodology. Notably, a meta-analytical approach that aggregated information across teams yielded a significant consensus in activated regions. Furthermore, prediction markets of researchers in the field revealed an overestimation of the likelihood of significant findings, even by researchers with direct knowledge of the dataset(2-5). Our findings show that analytical flexibility can have substantial effects on scientific conclusions, and identify factors that may be related to variability in the analysis of functional magnetic resonance imaging. The results emphasize the importance of validating and sharing complex analysis workflows, and demonstrate the need for performing and reporting multiple analyses of the same data. Potential approaches that could be used to mitigate issues related to analytical variability are discussed. The results obtained by seventy different teams analysing the same functional magnetic resonance imaging dataset show substantial variation, highlighting the influence of analytical choices and the importance of sharing workflows publicly and performing multiple analyses.
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| 12. |
- Chen, Geng, et al.
(author)
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Heisenberg-scaling measurement of the single-photon Kerr non-linearity using mixed states
- 2018
-
In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 9
-
Journal article (peer-reviewed)abstract
- Improving the precision of measurements is a significant scientific challenge. Previous works suggest that in a photon-coupling scenario the quantum fisher information shows a quantum-enhanced scaling of N-2, which in theory allows a better-than-classical scaling in practical measurements. In this work, utilizing mixed states with a large uncertainty and a post-selection of an additional pure system, we present a scheme to extract this amount of quantum fisher information and experimentally attain a practical Heisenberg scaling. We performed a measurement of a single-photon's Kerr non-linearity with a Heisenberg scaling, where an ultra-small Kerr phase of. 6 x 10(-8) rad was observed with a precision of similar or equal to 3.6 x 10(-10) rad. From the use of mixed states, the upper bound of quantum fisher information is improved to 2N(2). Moreover, by using an imaginary weak-value the scheme is robust to noise originating from the self-phase modulation.
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| 13. |
- Cheng, Cheng, et al.
(author)
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Deep H i Mapping of Stephan's Quintet and Its Neighborhood
- 2023
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In: Astrophysical Journal. - 0004-637X. ; 954:1
-
Journal article (peer-reviewed)abstract
- We carried out deep mapping observations of the atomic hydrogen (H i) 21 cm line emission in a field centered on the famous galaxy group Stephan's Quintet (SQ), using the Five-hundred-meter Aperture Spherical Telescope (FAST) equipped with a 19-beam receiver. The final data cube reaches an H i column density sensitivity of 5σ = 2.1 × 1017 cm-2 per 20 km s-1 channel with an angular resolution of 4.′0. The discovery of a large diffuse feature of the H i emission in the outskirts of the intragroup medium of SQ was reported in a previous paper (Xu et al.). Here we present a new study of the total H i emission of SQ and the detection of several neighboring galaxies, exploiting the high sensitivity and the large sky coverage of the FAST observations. A total H i mass of M H I = 3.48 ± 0.35 × 1010 M ☉ is found for SQ, which is significantly higher than previous measurements in the literature. This indicates that, contrary to earlier claims, SQ is not H i deficient. The excessive H i gas is mainly found in the velocity ranges of 6200-6400 km s-1 and 6800-7000 km s-1, which were undetected in previous observations that are less sensitive than ours. Our results suggest that the "missing H i"in compact groups may be hidden in the low-density diffuse neutral gas instead of in the ionized gas.
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| 14. |
- Cui, Liang, et al.
(author)
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Four additional natural 7-deazaguanine derivatives in phages and how to make them
- 2023
-
In: Nucleic Acids Research. - : Oxford University Press. - 0305-1048 .- 1362-4962. ; 51:17, s. 9214-9226
-
Journal article (peer-reviewed)abstract
- Bacteriophages and bacteria are engaged in a constant arms race, continually evolving new molecular tools to survive one another. To protect their genomic DNA from restriction enzymes, the most common bacterial defence systems, double-stranded DNA phages have evolved complex modifications that affect all four bases. This study focuses on modifications at position 7 of guanines. Eight derivatives of 7-deazaguanines were identified, including four previously unknown ones: 2 & PRIME;-deoxy-7-(methylamino)methyl-7-deazaguanine (mdPreQ(1)), 2 & PRIME;-deoxy-7-(formylamino)methyl-7-deazaguanine (fdPreQ(1)), 2 & PRIME;-deoxy-7-deazaguanine (dDG) and 2 & PRIME;-deoxy-7-carboxy-7-deazaguanine (dCDG). These modifications are inserted in DNA by a guanine transglycosylase named DpdA. Three subfamilies of DpdA had been previously characterized: bDpdA, DpdA1, and DpdA2. Two additional subfamilies were identified in this work: DpdA3, which allows for complete replacement of the guanines, and DpdA4, which is specific to archaeal viruses. Transglycosylases have now been identified in all phages and viruses carrying 7-deazaguanine modifications, indicating that the insertion of these modifications is a post-replication event. Three enzymes were predicted to be involved in the biosynthesis of these newly identified DNA modifications: 7-carboxy-7-deazaguanine decarboxylase (DpdL), dPreQ(1) formyltransferase (DpdN) and dPreQ(1) methyltransferase (DpdM), which was experimentally validated and harbors a unique fold not previously observed for nucleic acid methylases.
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| 15. |
- de las Fuentes, Lisa, et al.
(author)
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Gene-educational attainment interactions in a multi-ancestry genome-wide meta-analysis identify novel blood pressure loci
- 2021
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In: Molecular Psychiatry. - : Springer Nature. - 1359-4184 .- 1476-5578. ; 26:6, s. 2111-2125
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Journal article (peer-reviewed)abstract
- Educational attainment is widely used as a surrogate for socioeconomic status (SES). Low SES is a risk factor for hypertension and high blood pressure (BP). To identify novel BP loci, we performed multi-ancestry meta-analyses accounting for gene-educational attainment interactions using two variables, “Some College” (yes/no) and “Graduated College” (yes/no). Interactions were evaluated using both a 1 degree of freedom (DF) interaction term and a 2DF joint test of genetic and interaction effects. Analyses were performed for systolic BP, diastolic BP, mean arterial pressure, and pulse pressure. We pursued genome-wide interrogation in Stage 1 studies (N = 117 438) and follow-up on promising variants in Stage 2 studies (N = 293 787) in five ancestry groups. Through combined meta-analyses of Stages 1 and 2, we identified 84 known and 18 novel BP loci at genome-wide significance level (P < 5 × 10-8). Two novel loci were identified based on the 1DF test of interaction with educational attainment, while the remaining 16 loci were identified through the 2DF joint test of genetic and interaction effects. Ten novel loci were identified in individuals of African ancestry. Several novel loci show strong biological plausibility since they involve physiologic systems implicated in BP regulation. They include genes involved in the central nervous system-adrenal signaling axis (ZDHHC17, CADPS, PIK3C2G), vascular structure and function (GNB3, CDON), and renal function (HAS2 and HAS2-AS1, SLIT3). Collectively, these findings suggest a role of educational attainment or SES in further dissection of the genetic architecture of BP.
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| 16. |
- de Vries, Paul S., et al.
(author)
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Multiancestry Genome-Wide Association Study of Lipid Levels Incorporating Gene-Alcohol Interactions
- 2019
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In: American Journal of Epidemiology. - : Oxford University Press. - 0002-9262 .- 1476-6256. ; 188:6, s. 1033-1054
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Journal article (peer-reviewed)abstract
- A person's lipid profile is influenced by genetic variants and alcohol consumption, but the contribution of interactions between these exposures has not been studied. We therefore incorporated gene-alcohol interactions into a multiancestry genome-wide association study of levels of high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglycerides. We included 45 studies in stage 1 (genome-wide discovery) and 66 studies in stage 2 (focused follow-up), for a total of 394,584 individuals from 5 ancestry groups. Analyses covered the period July 2014-November 2017. Genetic main effects and interaction effects were jointly assessed by means of a 2-degrees-of-freedom (df) test, and a 1-df test was used to assess the interaction effects alone. Variants at 495 loci were at least suggestively associated (P < 1 x 10(-6)) with lipid levels in stage 1 and were evaluated in stage 2, followed by combined analyses of stage 1 and stage 2. In the combined analysis of stages 1 and 2, a total of 147 independent loci were associated with lipid levels at P < 5 x 10(-8) using 2-df tests, of which 18 were novel. No genome-wide-significant associations were found testing the interaction effect alone. The novel loci included several genes (proprotein convertase subtilisin/kexin type 5 (PCSK5), vascular endothelial growth factor B (VEGFB), and apolipoprotein B mRNA editing enzyme, catalytic polypeptide 1 (APOBEC1) complementation factor (A1CF)) that have a putative role in lipid metabolism on the basis of existing evidence from cellular and experimental models.
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| 17. |
- Du, Yaoyao, et al.
(author)
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Cartilage Oligomeric Matrix Protein Inhibits Vascular Smooth Muscle Calcification by Interacting With Bone Morphogenetic Protein-2.
- 2011
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In: Circulation Research. - 1524-4571. ; 108, s. 79-917
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Journal article (peer-reviewed)abstract
- Rationale: Vascular calcification is a significant contributor to cardiovascular morbidity and mortality. We recently reported that cartilage oligomeric matrix protein (COMP) is pivotal for maintaining the homeostasis of vascular smooth muscle cells (VSMCs). Whether COMP affects the process of vascular calcification is unknown. Objective: We aimed to test whether COMP modulates vascular calcification. Methods and Results: VSMC calcification in vitro was induced by calcifying media containing high inorganic phosphate or calcium. In vivo medial vessel calcification was induced in rats by 5/6 nephrectomy with a high-phosphate diet or by periadventitial application of CaCl(2) to the abdominal aorta. COMP protein level was markedly reduced in both calcified VSMCs and arteries. COMP deficiency remarkably exacerbated VSMC calcification, whereas ectopic expression of COMP greatly reduced calcification. Furthermore, COMP knockdown facilitated osteogenic markers expression by VSMCs even in the absence of calcifying media. By contrast, COMP overexpression significantly inhibited high phosphate- or high calcium-induced VSMC osteochondrogenic transition. Induction of osteogenic marker expression by COMP silencing was reversed by a soluble form of bone morphogenetic protein (BMP)-2 receptor IA, which suggests a BMP-2-dependent mechanism. Our data revealed that COMP bound directly to BMP-2 through the C terminus, inhibited BMP-2 receptor binding, and blocked BMP-2 osteogenic signaling, indicating COMP inhibits osteochondrogenic transition of VSMCs at least partially through inhibiting BMP-2. Conclusions: Our data strongly suggest that COMP is a novel inhibitor of vascular calcification. The imbalance between the effects of COMP and BMP-2 may provide new insights into the pathophysiology of vascular calcification.
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| 18. |
- Feitosa, Mary F., et al.
(author)
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Novel genetic associations for blood pressure identified via gene-alcohol interaction in up to 570K individuals across multiple ancestries
- 2018
-
In: PLOS ONE. - : Public library science. - 1932-6203. ; 13:6
-
Journal article (peer-reviewed)abstract
- Heavy alcohol consumption is an established risk factor for hypertension; the mechanism by which alcohol consumption impact blood pressure (BP) regulation remains unknown. We hypothesized that a genome-wide association study accounting for gene-alcohol consumption interaction for BP might identify additional BP loci and contribute to the understanding of alcohol-related BP regulation. We conducted a large two-stage investigation incorporating joint testing of main genetic effects and single nucleotide variant (SNV)-alcohol consumption interactions. In Stage 1, genome-wide discovery meta-analyses in approximate to 131 K individuals across several ancestry groups yielded 3,514 SNVs (245 loci) with suggestive evidence of association (P <1.0 x 10(-5)). In Stage 2, these SNVs were tested for independent external replication in individuals across multiple ancestries. We identified and replicated (at Bonferroni correction threshold) five novel BP loci (380 SNVs in 21 genes) and 49 previously reported BP loci (2,159 SNVs in 109 genes) in European ancestry, and in multi-ancestry meta-analyses (P < 5.0 x 10(-8)). For African ancestry samples, we detected 18 potentially novel BP loci (P< 5.0 x 10(-8)) in Stage 1 that warrant further replication. Additionally, correlated meta-analysis identified eight novel BP loci (11 genes). Several genes in these loci (e.g., PINX1, GATA4, BLK, FTO and GABBR2 have been previously reported to be associated with alcohol consumption. These findings provide insights into the role of alcohol consumption in the genetic architecture of hypertension.
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| 19. |
- Feng, Wenqing, et al.
(author)
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A novel change detection approach for multi-temporal high-resolution remote sensing images based on rotation forest and coarse-to-fine uncertainty analyses
- 2018
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In: Remote Sensing. - : MDPI AG. - 2072-4292. ; 10:7
-
Journal article (peer-reviewed)abstract
- In the process of object-based change detection (OBCD), scale is a significant factor related to extraction and analyses of subsequent change data. To address this problem, this paper describes an object-based approach to urban area change detection (CD) using rotation forest (RoF) and coarse-to-fine uncertainty analyses of multi-temporal high-resolution remote sensing images. First, highly homogeneous objects with consistent spatial positions are identified through vector-raster integration and multi-scale fine segmentation. The multi-temporal images are stacked and segmented under the constraints of a historical land use vector map using a series of optimal segmentation scales, ranging from coarse to fine. Second, neighborhood correlation image analyses are performed to highlight pixels with high probabilities of being changed or unchanged, which can be used as a prerequisite for object-based analyses. Third, based on the coarse-to-fine segmentation and pixel-based pre-classification results, change possibilities are calculated for various objects. Furthermore, changed and unchanged objects identified at different scales are automatically selected to serve as training samples. The spectral and texture features of each object are extracted. Finally, uncertain objects are classified using the RoF classifier. Multi-scale classification results are combined using a majority voting rule to generate the final CD results. In experiments using two pairs of real high-resolution remote sensing datasets, our proposed approach outperformed existing methods in terms of CD accuracy, verifying its feasibility and effectiveness.
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| 20. |
- Feng, Wenqing, et al.
(author)
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Building extraction from VHR remote sensing imagery by combining an improved deep convolutional encoder-decoder architecture and historical land use vector map
- 2020
-
In: International Journal of Remote Sensing. - : Informa UK Limited. - 0143-1161 .- 1366-5901. ; 41:17, s. 6595-6617
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Journal article (peer-reviewed)abstract
- Building extraction has attracted considerable attention in the field of remote sensing image analysis. Fully convolutional network modelling is a recently developed technique that is capable of significantly enhancing building extraction accuracy. It is a prominent branch of deep learning and uses advanced state-of-the-art techniques, especially with regard to building segmentation. In this paper, we present an enhanced deep convolutional encoder-decoder (DCED) network by incorporating historical land use vector maps (HVMs) customized for building extraction. The approach combines enhanced DCED architecture with multi-scale image pyramid for pixel-wise building segmentation. The improved DCED network, together with symmetrical dense-shortcut connection structures, is employed to establish the encoders for automatic extraction of building features. The feature maps from early layers were fused with more discriminative feature maps from the deeper layers through ‘Res path’ skip connections for superior building extraction accuracy. To further reduce the occurrence of falsely segmented buildings, and to sharpen the buildings’ boundaries, the new temporal testing image is segmented under the constraints of an HVM. A majority voting strategy is employed to ensure the homogeneity of the building objects as the post-processing method. Experimental results indicate that the proposed approach exhibits competitive quantitative and qualitative performance, effectively alleviating the salt-and-pepper phenomenon and block effects, and retaining the edge structures of buildings. Compared with other state-of-the-art methods, our method demonstrably achieves the optimal final accuracies.
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| 21. |
- Feng, Wenqing, et al.
(author)
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Water Body Extraction From Very High-Resolution Remote Sensing Imagery Using Deep U-Net and a Superpixel-Based Conditional Random Field Model
- 2019
-
In: IEEE Geoscience and Remote Sensing Letters. - 1545-598X. ; 16:4, s. 618-622
-
Journal article (peer-reviewed)abstract
- Water body extraction (WBE) has attracted considerable attention in the field of remote sensing image analysis. Herein, we present an enhanced deep convolutional encoder-decoder (DCED) network (or Deep U-Net) specifically tailored to WBE from remote sensing images by applying superpixel segmentation and conditional random fields (CRFs). First, we preclassify the entire remote sensing image into the water and nonwater areas via Deep U-Net, using the results of class membership probabilities as the unary potential in the CRF model. The pairwise potential of CRF is defined by a linear combination of Gaussian kernels, which forms a fully connected neighbor structure. Next, regional restriction is incorporated into the approach to enhance the consistency of the connected area. We use the simple linear iterative clustering algorithm to generate superpixels and correct the binary classification results by calculating their average posterior probabilities. Finally, a highly efficient approximate inference algorithm, mean-field inference, is generated for the final model. The results from the experimental application to GaoFen-2 images and WorldView-2 images demonstrate that the proposed approach exhibits competitive quantitative and qualitative performance, which effectively reduces salt-and-pepper noise and retains the edge structures of water bodies. Compared to existing state-of-the-art methods, our proposed method achieves superior final results.
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| 22. |
- Huang, Yuanyuan, et al.
(author)
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Hidden spin polarization in the centrosymmetric Mo S2 crystal revealed via elliptically polarized terahertz emission
- 2020
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In: Physical Review B. - 2469-9950. ; 102:8
-
Journal article (peer-reviewed)abstract
- The spin polarization in centrosymmetric molybdenum disulfide (MoS2) bulk crystal is recorded by helicity dependent photocurrent exposed as elliptically polarized terahertz (THz) emission. We assign this observation to hidden spin polarization due to the local Dresselhaus effect induced by the molybdenum atomic site asymmetry. This spin polarization induces ultrafast optically controlled circular photogalvanic current that results in elliptically polarized THz emission. Furthermore, this THz radiation exhibits a helicity dependent bleaching effect under opposite circularly polarized excitations due to the spin relaxation. Our results demonstrate the viability of all-optical control of hidden spin polarization in two-dimensional materials and propose the applicability of the THz emission spectroscopy as a sensitive and contactless method to study spintronic physics in two-dimensional materials.
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| 23. |
- Li, Xiane, et al.
(author)
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Mapping the energy level alignment at donor/acceptor interfaces in non-fullerene organic solar cells
- 2022
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In: Nature Communications. - : Nature Portfolio. - 2041-1723. ; 13:1
-
Journal article (peer-reviewed)abstract
- Energy level alignment (ELA) at donor-acceptor heterojunctions is of vital importance yet largely undetermined in organic solar cells. Here, authors determine the heterojunction ELA with (mono) layer-by-layer precision to understand the co-existence of efficient charge. Energy level alignment (ELA) at donor (D) -acceptor (A) heterojunctions is essential for understanding the charge generation and recombination process in organic photovoltaic devices. However, the ELA at the D-A interfaces is largely underdetermined, resulting in debates on the fundamental operating mechanisms of high-efficiency non-fullerene organic solar cells. Here, we systematically investigate ELA and its depth-dependent variation of a range of donor/non-fullerene-acceptor interfaces by fabricating and characterizing D-A quasi bilayers and planar bilayers. In contrast to previous assumptions, we observe significant vacuum level (VL) shifts existing at the D-A interfaces, which are demonstrated to be abrupt, extending over only 1-2 layers at the heterojunctions, and are attributed to interface dipoles induced by D-A electrostatic potential differences. The VL shifts result in reduced interfacial energetic offsets and increased charge transfer (CT) state energies which reconcile the conflicting observations of large energy level offsets inferred from neat films and large CT energies of donor - non-fullerene-acceptor systems.
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| 24. |
- Liang, Wang, et al.
(author)
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Life cycle assessment of blast furnace ironmaking processes : A comparison of fossil fuels and biomass hydrochar applications
- 2023
-
In: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 345
-
Journal article (peer-reviewed)abstract
- The impact of the iron and steel production process on the ecological environment cannot be ignored. This study aims to assess the impact of life cycle assessment on the traditional fossil fuel blast furnace ironmaking process and the biomass hydrochar blast furnace ironmaking process. The Simapro v9.0 software is used to comprehensively evaluate the life cycle impacts of biomass hydrochar in the blast furnace ironmaking process. The results show that the life cycle impact categories of the blast furnace ironmaking process mainly include global warming, non-renewable energy and respiratory inorganics. The global warming impact of the ironmaking process using hydrochar is 2054.00 kg CO2 eq, which is 420.61 kg CO2 eq less than that of traditional blast furnace ironmaking process. The global warming impact is mainly reflected in the emission of CO2 gas, and the main source is the generation of blast furnace gas and the use of sinter. The respiratory inorganics impact is mainly manifested in the emission of nitrogen oxides, sulfur oxides and particulates, which mainly comes from the mining of iron ore and the production of sinter. The non-renewable energy impact mainly comes from the coal resources, and the use of other renewable energy such as biomass energy is an important way to reduce the impact. Therefore, biomass hydrochar used in the metallurgical process is more suitable for sustainable devel-opment of the ecological environment.
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| 25. |
- Liu, Wei, et al.
(author)
-
Coherent dynamics of multi-spin V-B(-) center in hexagonal boron nitride
- 2022
-
In: Nature Communications. - : Nature Portfolio. - 2041-1723. ; 13:1
-
Journal article (peer-reviewed)abstract
- Hexagonal boron nitride (hBN) has recently been demonstrated to contain optically polarized and detected electron spins that can be utilized for implementing qubits and quantum sensors in nanolayered-devices. Understanding the coherent dynamics ofmicrowave driven spins in hBN is of crucial importance for advancing these emerging new technologies. Here, we demonstrate and study the Rabi oscillation and related phenomena of a negatively charged boron vacancy (V-B(-)) spin ensemble in hBN. We report on different dynamics of the V-B(-) spins at weak and strong magnetic fields. In the former case the defect behaves like a single electron spin system, while in the latter case it behaves like a multi-spin system exhibiting multiple-frequency dynamical oscillation as beat in the Ramsey fringes. We also carry out theoretical simulations for the spin dynamics of V-B(-) and reveal that the nuclear spins can be driven via the strong electron nuclear coupling existing in V-B(-) center, which can be modulated by the magnetic field and microwave field.
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| 26. |
- Shi, Yu-Sheng, et al.
(author)
-
Limonoids from Citrus : Chemistry, anti-tumor potential, and other bioactivities
- 2020
-
In: Journal of Functional Foods. - : ELSEVIER. - 1756-4646 .- 2214-9414. ; 75
-
Journal article (peer-reviewed)abstract
- Citrus limonoids are tetranortriterpenoids compounds mainly found in oranges, lemons, grapefruits, and other fruits of Citrus. They are proved to be the leading cause of bitterness in Citrus fruits and are mainly consumed for therapeutic purposes and as food. Numerous studies have focused on Citrus limonoids and intend to develop new chemotherapeutic or complementary medicine in recent years. Citrus limonoids showed various bioactivities such as anti-tumor, antioxidative, anti-inflammatory, anti-neurological diseases, immunomodulatory, anti -insect, anti-bacteria, antiviral activities, etc. This review summarized limonoids from Citrus to date, along with their chemical structures and biological activities with a particular focus on their anti-tumor potential.
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| 27. |
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| 28. |
- Song, Tengfei, et al.
(author)
-
Effect of carbonization conditions on the property and structure of bamboo char for injection in blast furnace
- 2019
-
In: ISIJ International. - : Iron and Steel Institute of Japan. - 0915-1559 .- 1347-5460. ; 59:3, s. 442-449
-
Journal article (peer-reviewed)abstract
- To evaluate the effect of carbonization conditions on the bamboo, the relationship between carbonization parameter and physicochemical characteristics was studied. The results indicated that the volatile matter drastically decreased with the increase of carbonization temperature, while the fixed carbon and fuel ratio (fixed carbon/volatile matter) increased. Excellent linearity between the fuel ratio and carbonization temperature was obtained. The energy yield decreased gradually when rising the carbonization temperature, whereas the change of heating value was not obvious. A new calculation model of higher heating value (HHV) was developed, and it could be used to predict HHV of the bamboo char more precisely at temperatures above 300°C. The positive impact of functional groups, specific surface area as well as catalysis of alkali metal may contribute to the combustion of bamboo char. The results showed that there is a feasible operating condition for the transformation of bamboo into char with the carbonization parameter at 400°C for 30 min.
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| 29. |
- Sung, Yun Ju, et al.
(author)
-
A multi-ancestry genome-wide study incorporating gene-smoking interactions identifies multiple new loci for pulse pressure and mean arterial pressure
- 2019
-
In: Human Molecular Genetics. - : Oxford University Press. - 0964-6906 .- 1460-2083. ; 28:15, s. 2615-2633
-
Journal article (peer-reviewed)abstract
- Elevated blood pressure (BP), a leading cause of global morbidity and mortality, is influenced by both genetic and lifestyle factors. Cigarette smoking is one such lifestyle factor. Across five ancestries, we performed a genome-wide gene–smoking interaction study of mean arterial pressure (MAP) and pulse pressure (PP) in 129 913 individuals in stage 1 and follow-up analysis in 480 178 additional individuals in stage 2. We report here 136 loci significantly associated with MAP and/or PP. Of these, 61 were previously published through main-effect analysis of BP traits, 37 were recently reported by us for systolic BP and/or diastolic BP through gene–smoking interaction analysis and 38 were newly identified (P < 5 × 10−8, false discovery rate < 0.05). We also identified nine new signals near known loci. Of the 136 loci, 8 showed significant interaction with smoking status. They include CSMD1 previously reported for insulin resistance and BP in the spontaneously hypertensive rats. Many of the 38 new loci show biologic plausibility for a role in BP regulation. SLC26A7 encodes a chloride/bicarbonate exchanger expressed in the renal outer medullary collecting duct. AVPR1A is widely expressed, including in vascular smooth muscle cells, kidney, myocardium and brain. FHAD1 is a long non-coding RNA overexpressed in heart failure. TMEM51 was associated with contractile function in cardiomyocytes. CASP9 plays a central role in cardiomyocyte apoptosis. Identified only in African ancestry were 30 novel loci. Our findings highlight the value of multi-ancestry investigations, particularly in studies of interaction with lifestyle factors, where genomic and lifestyle differences may contribute to novel findings.
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| 30. |
- Tian, Yu-Peng, et al.
(author)
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Investigations and facile synthesis of a series of novel multi-functional two-photon absorption materials
- 2007
-
In: Journal of Materials Chemistry. - : Royal Society of Chemistry (RSC). - 0959-9428 .- 1364-5501. ; 17:34, s. 3646-3654
-
Journal article (peer-reviewed)abstract
- Six centrosymmetric D-(pi-A)(3) structural triphenylamine derivatives that can be used as two- photon photopolymerization and optical data storage chromophores, tris[ 4-( 4- pyridylethenyl) phenyl] amine ( 1), tris[ 4-( 2- pyridylethenyl) phenyl] amine ( 2), tris( 4- cyanoethenylphenyl) amine ( 3), tris[ 4- butylacrylatephenyl] amine ( 4), tris[ 4- methylacrylatephenyl] amine ( 5) and tris[ 4- acrylicethenylphenyl] amine ( 6), have been successfully synthesized via a triple palladium-catalyzed Heck coupling reaction, and the novel chromophores were fully characterized by elemental analysis, IR, (1)H-NMR and ESIMS. The structure for 3 was determined by single crystal X-ray diffraction study. One- and two-photon absorption and fluorescence in various solvents were experimentally investigated. Two-photon initiated polymerization microfabrication and optical data recording experiments were carried out under 780 nm laser radiation, and the possible polymerization mechanism is discussed based on theoretical calculations. All the six chromophores have relatively large two-photon absorption crosssections, and exhibit optical memory and highly efficient two-photon initiated polymerization abilities.
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| 31. |
- Wang, Chuan-Kui
(author)
-
Electronic Structure and Transport in Nanofabricated Low-Dimensional Semiconductor Systems : A theoretical study
- 1997
-
Doctoral thesis (other academic/artistic)abstract
- Systematic studies of the transport properties in one type of low-dimensional semiconductor nanostructures, in which the motion of carriers is governed by quantum mechanics, are presented in this thesis. In addition, the electronic states in lowdimensional systems fabricated from GaAs / Al?Ga1-?As heterostructures have been investigated by using both transport methods and the static calculations.The mode-matching technique and transfer-matrix method are employed to explore the motion of electrons in a double-bend quantum wire. The conductance of the quantum system is calculated as a function of Fermi energy. Special attentions have been paid to the resonant peaks in conductances at Fermi energies lower than the threshold energy of the lowest subband. The charge distributions and the current flows at these Fermi energies have also been visualized. The bound states in such classically unbound systems can be probed by the resonant peaks in the conductance. For a quantum wire with a multiple of double-bend discontinuities, miniband structures, related to the split bound states, have been investigated. Ananalytical expression is suggested to elucidate these features. Additionly, detailed investigations have been extended to thermal and nonlinear effects, and to the influence of geometrical shapes.Many-body interactions, expected to play a great role in low-dimensional systems, have been considered. We have calculated the electronic states of a quantum wire with a cross section by density-functional theories. Results indicate that the energy cost for putting two electrons with opposite spins into one bound state is larger than the binding energy, i.e., one bound state can be occupied by only one electron.Spin-density-functional theories are used to study the exchange effects and magnetic effects on the electronic states of an infinite quantum wire with an inplane magnetic field parallel to the wire. The intrinsic properties of the system have been given. The theories have further been applied to a quantum point contact in the one subband limit. The spin-dependent saddle potentials have been observed. The semi-classical Thomas-Fermi and related models have been examined for semiconductor systems of the kind considered in this thesis. It has been shown that these models are suitable for dealing with these systems qualitatively.
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| 32. |
- Wang, Chuanfei, et al.
(author)
-
Low Band Gap Polymer Solar Cells With Minimal Voltage Losses
- 2016
-
In: Advanced Energy Materials. - : Wiley. - 1614-6832 .- 1614-6840. ; 6:18
-
Journal article (peer-reviewed)abstract
- One of the factors limiting the performance of organic solar cells (OSCs) is their large energy losses (E loss) in the conversion from photons to electrons, typically believed to be around 0.6 eV and often higher than those of inorganic solar cells. In this work, a novel low band gap polymer PIDTT-TID with a optical gap of 1.49 eV is synthesized and used as the donor combined with PC71BM in solar cells. These solar cells attain a good power conversion efficiency of 6.7% with a high open-circuit voltage of 1.0 V, leading to the E loss as low as 0.49 eV. A systematic study indicates that the driving force in this donor and acceptor system is sufficient for charge generation with the low E loss. This work pushes the minimal E loss of OSCs down to 0.49 eV, approaching the values of some inorganic and hybrid solar cells. It indicates the potential for further enhancement of the performance of OSCs by improving their V oc since the E loss can be minimized.
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| 33. |
- Wang, Chuanfei, et al.
(author)
-
Ternary organic solar cells with enhanced open circuit voltage
- 2017
-
In: Nano Energy. - : Elsevier BV. - 2211-2855 .- 2211-3282. ; 37, s. 24-31
-
Journal article (peer-reviewed)abstract
- By introducing a non-fullerene small molecule acceptor as a third component to typical polymer donor: fullerene acceptor binary solar cells, we demonstrate that the short circuit current density (Jsc), open circuit voltage (Voc), power conversion efficiency (PCE) and thermal stability can be enhanced simultaneously. The different surface energy of each component causes most of the non-fullerene acceptor molecules to self-organize at the polymer/fullerene interface, while the appropriately selected oxidation/reduction potential of the non-fullerene acceptor enables the resulting ternary junction to work through a cascade mechanism. The cascade ternary junction enhances charge generation through complementary absorption between the non-fullerene and fullerene acceptors and aids the efficient charge extraction from fullerene domains. The bimolecular recombination in the ternary blend layer is reduced as the ternary cascade junction increases the separation of holes and electrons during charge transportation and the trap assistant recombination induced by integer charge transfer (ICT) state potentially reduced due to the smaller pinning energy of inserted non-fullerene acceptor, leading to an unprecedented increase in the open circuit voltage beyond the binary reference values.
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| 34. |
- Wang, Guangwei, et al.
(author)
-
Application of catalysts in biomass hydrothermal carbonization for the preparation of high-quality blast furnace injection fuel
- 2023
-
In: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 283
-
Journal article (peer-reviewed)abstract
- The low energy density of biomass is a crucial limitation for their application in the steel industry. This study used catalyst-catalysed hydrothermal carbonization (HTC) to prepare higher-quality hydrochar from biomass. The effects of acid-base homogeneous catalysts (Fe(NO3)3·9H2O and CaO), liquid phase product (circulating water) and carbonization temperatures on the physicochemical properties and microscopic morphology of hydrochars were investigated. The results showed that higher carbonization temperature, circulating water and Fe(NO3)3·9H2O all raised the higher heating value (HHV) of hydrochar. When 4% of Fe(NO3)3·9H2O was added, the HHV of hydrochar reached 30.05 MJ/kg, which was 1.15 times higher than without catalysts. The above three conditions can also make the ordering degree in the carbonaceous structure lower ordered and enhance the reaction performance of the hydrochar. Meanwhile, the addition of Fe(NO3)3·9H2O at 240 °C can reduce the hydrochar ignition and burnout temperatures and enhance the combustion performance. Moreover, it was demonstrated that circulating water promoted the HTC more than deionized water. In conclusion, adding Fe(NO3)3·9H2O or circulating water to the HTC process can produce higher-quality hydrochar.
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| 35. |
- Wang, Guangwei, et al.
(author)
-
Preparation of Biomass Hydrochar and Application Analysis of Blast Furnace Injection
- 2023
-
In: Energies. - : MDPI AG. - 1996-1073. ; 16:3
-
Journal article (peer-reviewed)abstract
- Hydrothermal carbonization (HTC) technology was used to carbonize and improve biomass raw material to obtain hydrochar. The effects of HTC temperature and holding time on the yield, composition, structure, combustion behavior, and safety of hydrochar were studied systematically. In addition, the results show that with the increase in HTC temperature and the prolongation of holding time, the yield of hydrochar gradually reduces, the fixed carbon content of hydrochar increases, the volatile content decreases, and a large number of ash and alkali metals enter the liquid phase and are removed. Further, the analysis of the combustion properties and the structure of hydrochar can be observed in that, as the HTC process promotes the occurrence of polymerization reactions, the specific surface area gradually reduces, the degree of carbon ordering increases, and the combustion curve moves toward the high-temperature zone and gradually approaches bituminous coal. Since biomass hydrochar has the characteristic of being carbon neutral, blast furnace injection hydrochar can reduce CO2 emissions, and every 1 kg/tHM of biomass hydrochar can reduce CO2 emissions by 1.95 kg/tHM.
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| 36. |
- Wang, Heyong, et al.
(author)
-
Efficient perovskite light-emitting diodes based on a solution-processed tin dioxide electron transport layer
- 2018
-
In: Journal of Materials Chemistry C. - : ROYAL SOC CHEMISTRY. - 2050-7526 .- 2050-7534. ; 6:26, s. 6996-7002
-
Journal article (peer-reviewed)abstract
- To achieve high-performance perovskite light-emitting diodes (PeLEDs), an appropriate functional layer beneath the perovskite emissive layer is significantly important to modulate the morphology of the perovskite film and to facilitate charge injection and transport in the device. Herein, for the first time, we report efficient n-i-p structured PeLEDs using solution-processed SnO2 as an electron transport layer. Three-dimensional perovskites, such as CH(NH2)(2)PbI3 and CH3NH3PbI3, are found to be more chemically compatible with SnO2 than with commonly used ZnO. In addition, SnO2 shows good transparency, excellent morphology and suitable energy levels. These properties make SnO2 a promising candidate in both three-and low-dimensional PeLEDs, among which a high external quantum efficiency of 7.9% has been realized. Furthermore, interfacial materials that are widely used to improve the device performances of ZnO-based PeLEDs are also applied on SnO2-based PeLEDs and their effects have been systematically studied. In contrast to ZnO, SnO2 modified by these interfacial materials shows detrimental effects due to photoluminescence quenching.
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| 37. |
- Wang, Junbo, et al.
(author)
-
Influence of Molecular Configurations on the Desulfonylation Reactions on Metal Surfaces
- 2022
-
In: Journal of the American Chemical Society. - : AMER CHEMICAL SOC. - 0002-7863 .- 1520-5126. ; 144:47, s. 21596-21605
-
Journal article (peer-reviewed)abstract
- On-surface synthesis is a powerful methodology for the fabrication of low-dimensional functional materials. The precursor molecules usually anchor on different metal surfaces via similar configurations. The activation energies are therefore solely determined by the chemical activity of the respective metal surfaces. Here, we studied the influence of the detailed adsorption configuration on the activation energy on different metal surfaces. We systematically studied the desulfonylation homocoupling for a molecular precursor on Au(111) and Ag(111) and found that the activation energy is lower on inert Au(111) than on Ag(111). Combining scanning tunneling microscopy observations, synchrotron radiation photoemission spectroscopy measurements, and density functional theory calculations, we elucidate that the phenomenon arises from different molecule-substrate interactions. The molecular precursors anchor on Au(111) via Au-S interactions, which lead to weakening of the phenyl-S bonds. On the other hand, the molecular precursors anchor on Ag(111) via Ag-O interactions, resulting in the lifting of the S atoms. As a consequence, the activation barrier of the desulfonylation reactions is higher on Ag(111), although silver is generally more chemically active than gold. Our study not only reports a new type of on-surface chemical reaction but also clarifies the influence of detailed adsorption configurations on specific on-surface chemical reactions.
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| 38. |
- Wang, Mingyi, et al.
(author)
-
Rapid growth of new atmospheric particles by nitric acid and ammonia condensation
- 2020
-
In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 581:7807, s. 184-
-
Journal article (peer-reviewed)abstract
- A list of authors and their affiliations appears at the end of the paper New-particle formation is a major contributor to urban smog(1,2), but how it occurs in cities is often puzzling(3). If the growth rates of urban particles are similar to those found in cleaner environments (1-10 nanometres per hour), then existing understanding suggests that new urban particles should be rapidly scavenged by the high concentration of pre-existing particles. Here we show, through experiments performed under atmospheric conditions in the CLOUD chamber at CERN, that below about +5 degrees Celsius, nitric acid and ammonia vapours can condense onto freshly nucleated particles as small as a few nanometres in diameter. Moreover, when it is cold enough (below -15 degrees Celsius), nitric acid and ammonia can nucleate directly through an acid-base stabilization mechanism to form ammonium nitrate particles. Given that these vapours are often one thousand times more abundant than sulfuric acid, the resulting particle growth rates can be extremely high, reaching well above 100 nanometres per hour. However, these high growth rates require the gas-particle ammonium nitrate system to be out of equilibrium in order to sustain gas-phase supersaturations. In view of the strong temperature dependence that we measure for the gas-phase supersaturations, we expect such transient conditions to occur in inhomogeneous urban settings, especially in wintertime, driven by vertical mixing and by strong local sources such as traffic. Even though rapid growth from nitric acid and ammonia condensation may last for only a few minutes, it is nonetheless fast enough to shepherd freshly nucleated particles through the smallest size range where they are most vulnerable to scavenging loss, thus greatly increasing their survival probability. We also expect nitric acid and ammonia nucleation and rapid growth to be important in the relatively clean and cold upper free troposphere, where ammonia can be convected from the continental boundary layer and nitric acid is abundant from electrical storms(4,5).
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| 39. |
- Wang, Xu-Dong, et al.
(author)
-
Note : Coherent resonances observed in the dissociative electron attachment to carbon monoxide
- 2015
-
In: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 143:6
-
Journal article (other academic/artistic)abstract
- Succeeding our previous finding about coherent interference of the resonant states of CO- formed by the low-energy electron attachment [Tian et al. Phys. Rev. A 88, 012708 (2013)], here we provide further evidence of the coherent interference. The completely backward distributions of the O- fragment of the temporary CO- are observed with anion velocity map imaging technique in an electron energy range of 11.3-12.6 eV and explained as the results of the coherent interferences of three resonant states. Furthermore, the state configuration of the interference is changed with the increase of electron attachment energy.
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| 40. |
- Wei, Chu, et al.
(author)
-
Recent advances in China's sustainable transition studies
- 2022
-
In: Letters in spatial and resource sciences. - : Springer Nature. - 1864-4031 .- 1864-404X. ; 15:3, s. 279-286
-
Journal article (peer-reviewed)abstract
- The world is confronted with increasing uncertainty and divisive threats to a sustainable global transition. Deglobalization is driving economic decoupling, and the pandemic is further preventing social exchange. The outcome of the 26th UN Climate Change Conference is a rare source of positive news. This special issue, entitled "Space Reconstruction in China's Sustainable Transition: Land, Energy and Carbon Emission", makes a timely academic contribution in response to these problems by presenting some recent research concerns and advances. This introductory article presents the latest policy debate and summarizes the major findings from six articles covered in the special issue. We show that academic society is worried about the negative effect of divisive trends on sustainable transition. Moreover, China's great spatial heterogeneity calls for an equitable and stable strategy to direct the transition process.
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| 41. |
- Wu, Jianlong, et al.
(author)
-
Study on Direct Reduction in Carbon-Bearing Pellets Using Biochar
- 2023
-
In: Sustainability. - : MDPI AG. - 2071-1050. ; 15:24
-
Journal article (peer-reviewed)abstract
- As a renewable, carbon-neutral raw material, the application of biomass in steel production is conducive to reducing greenhouse gas emissions and achieving green and sustainable development in the steel industry. The heating and reduction process of a rotary hearth furnace was simulated under laboratory conditions to roast and reduce biochar carbon-bearing pellets with coke powder and anthracite carbon-bearing pellets as a comparison. This was conducted to investigate the impact of biochar as a reducing agent on the direct reduction in carbon-bearing pellets. Under various reduction temperatures, carbon/oxygen ratios, and reduction times, tests were conducted on the compressive strength and metallization rate of carbon-bearing pellets made using typical binder bentonite. Results show that with the increase in reduction temperature, the metallization rate of pellets increases, while the compressive strength initially decreases and then increases, reaching the lowest point at 900 degrees C and 1000 degrees C. When the ratio of carbon to oxygen is between 0.7 and 0.9 and the reduction time is between 15 and 25 min, carbon-bearing pellets meet the requirements of both the metallization rate and the strength, with the metallization rate above 80%. However, severe volume swelling and low strength were observed in biochar carbon-bearing pellets at 900 degrees C and 1000 degrees C, which negatively impacted multi-layered charging and heat transfer efficiency in the blast furnace. Therefore, a novel laboratory-prepared binder was introduced in the preparation process of biochar carbon-bearing pellets at an appropriate addition ratio of 5-8%. Without producing any swelling concerns, the inclusion of this binder considerably improved the compression strength and metallization rate of the pellets, enabling them to fulfill the standards for raw materials in the blast furnace.
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| 42. |
- Wu, Xiao-Ling, et al.
(author)
-
Coupled Hydraulic and Kalman Filter Model for Real-Time Correction of Flood Forecast in the Three Gorges Interzone of Yangtze River, China
- 2013
-
In: Journal of hydrologic engineering. - 1084-0699 .- 1943-5584. ; 18:11, s. 1416-1425
-
Journal article (peer-reviewed)abstract
- The Three Gorges Project along the Yangtze River in China, as one of the biggest hydropower-complex projects in the world, plays a significant role in the economic development of the area even of the whole nation. An accurate and reliable flood forecast modeling system is of significant importance for flood control, flood warning, and operation of larger reservoirs. Kalman filter coupling with hydrological models or hydraulic models is one of the efficient methods to adjust real-time flood series for reducing errors from model structure, input data, and calibrated parameters. However, the coupling model is time consuming in computation because the state vectors in this kind of Kalman filter including both water stage and discharge are solved simultaneously. In this study, an alternative coupling method was developed, which separates system state equations and measurement equations allowing the water stage and discharge to be computed alternately. The new method was applied for real-time flood forecasting in the Three Gorges interzone of Yangtze River. The hydraulic model is calibrated and verified against the observed flood stage and discharge before and during Three Gorges Dam construction periods. Study results demonstrate that the new model is efficient in real-time flood forecasting. A comparative study shows that the newly developed approach outperforms the conventional methods in terms of modeling efficiency, root mean square error, as well as the forecasting errors in the maximum water stage and peak flow.
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| 43. |
- Xiao, Ya, et al.
(author)
-
Experimental nonlocal steering of Bohmian trajectories
- 2017
-
In: Optics Express. - : Optical Society of America. - 1094-4087. ; 25:13, s. 14463-14472
-
Journal article (peer-reviewed)abstract
- Interpretations of quantum mechanics (QM), or proposals for underlying theories, that attempt to present a definite realist picture, such as Bohmian mechanics, require strong non-local effects. Naively, these effects would violate causality and contradict special relativity. However if the theory agrees with QM the violation cannot be observed directly. Here, we demonstrate experimentally such an effect: we steer the velocity and trajectory of a Bohmian particle using a remote measurement. We use a pair of photons and entangle the spatial transverse position of one with the polarization of the other. The first photon is sent to a double-slit-like apparatus, where its trajectory is measured using the technique of Weak Measurements. The other photon is projected to a linear polarization state. The choice of polarization state, and the result, steer the first photon in the most intuitive sense of the word. The effect is indeed shown to be dramatic, while being easy to visualize. We discuss its strength and what are the conditions for it to occur.
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| 44. |
- Xiao, Ya, et al.
(author)
-
Observing momentum disturbance in double-slit which-way measurements
- 2019
-
In: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 5:6
-
Journal article (peer-reviewed)abstract
- Making a which-way measurement (WWM) to identify which slit a particle goes through in a double-slit apparatus will reduce the visibility of interference fringes. There has been a long-standing controversy over whether this can be attributed to an uncontrollable momentum transfer. Here, by reconstructing the Bohmian trajectories of single photons, we experimentally obtain the distribution of momentum change. For our WWM, the change we see is not a momentum kick that occurs at the point of the WWM, but rather one that nonclassically accumulates during the propagation of the photons. We further confirm a quantitative relation between the loss of visibility consequent on a WWM and the total (late-time) momentum disturbance. Our results emphasize the role of the Bohmian momentum in giving an intuitive picture of wave-particle duality and complementarity.
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| 45. |
- Xu, Jin-Long, et al.
(author)
-
Formation of a Massive Lenticular Galaxy Under the Tidal Interaction with a Group of Dwarf Galaxies
- 2023
-
In: Astrophysical Journal Letters. - 2041-8213 .- 2041-8205. ; 958:2
-
Journal article (peer-reviewed)abstract
- Based on the atomic-hydrogen (H i) observations using the Five-hundred-meter Aperture Spherical radio Telescope, we present a detailed study of the gas-rich massive S0 galaxy NGC 1023 in a nearby galaxy group. The presence of a H i extended warped disk in NGC 1023 indicates that this S0 galaxy originated from a spiral galaxy. The data also suggest that NGC 1023 is interacting with four dwarf galaxies. In particular, one of the largest dwarf galaxies has fallen into the gas disk of NGC 1023, forming a rare bright-dark galaxy pair with a large gas clump. This clump shows the signature of a galaxy but has no optical counterpart, implying that it is a newly formed starless galaxy. Our results first suggest that a massive S0 galaxy in a galaxy group can form via the morphological transformation from a spiral under the joint action of multiple tidal interactions.
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| 46. |
- Yang, Jia-Xiang, et al.
(author)
-
Facile synthesis, optical properties and theoretical calculation of two novel two-photon absorption chromophores
- 2010
-
In: Journal of Luminescence. - : Elsevier BV. - 0022-2313 .- 1872-7883. ; 130:4, s. 654-659
-
Journal article (peer-reviewed)abstract
- Two heterocycle-based derivatives that can be used as two-photon absorption chromophore, 9-butyl-3-(2,6-diphenylpyridin-4-yl)-9H-carbazole (BDPYC) and 9-butyl-3-(4-(2, 6-diphenylpyridin-4-yl)styryl)-9H-carbazole (BDPSC) have been successfully synthesized and fully characterized by elemental analysis, IR, H-1 NMR, C-13 NMR and MS. The molecules possess D-pi-A structures, but have different pi bridge. The 9-butylcarbazole is used as a donor (D), and the pyridine ring is used as an acceptor (A). One- and two-photon absorption and excited fluorescence properties in various solvents were experimentally investigated. Two-photon initiated optical data recording experiments have been carried Out under 740 nm laser radiation, and the possible mechanism of optical data storage is discussed based on theoretical calculations.
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| 47. |
- Yu, Di, et al.
(author)
-
Adenovirus Serotype 5 Vectors with Tat-PTD Modified Hexon and Serotype 35 Fiber Show Greatly Enhanced Transduction Capacity of Primary Cell Cultures
- 2013
-
In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:1, s. e54952-
-
Journal article (peer-reviewed)abstract
- Recombinant adenovirus serotype 5 (Ad5) vectors represent one of the most efficient gene delivery vectors in life sciences. However, Ad5 is dependent on expression of the coxsackievirus-adenovirus- receptor (CAR) on the surface of target cell for efficient transduction, which limits it's utility for certain cell types. Herein we present a new vector, Ad5PTDf35, which is an Ad5 vector having serotype 35 fiber-specificity and Tat-PTD hexon-modification. This vector shows dramatically increased transduction capacity of primary human cell cultures including T cells, monocytes, macrophages, dendritic cells, pancreatic islets and exocrine cells, mesenchymal stem cells and tumor initiating cells. Biodistribution in mice following systemic administration (tail-vein injection) show significantly reduced uptake in the liver and spleen of Ad5PTDf35 compared to unmodified Ad5. Therefore, replication-competent viruses with these modifications may be further developed as oncolytic agents for cancer therapy. User-friendly backbone plasmids containing these modifications were developed for compatibility to the AdEasy-system to facilitate the development of surface-modified adenoviruses for gene delivery to difficult-to-transduce cells in basic, pre-clinical and clinical research.
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| 48. |
- Yuan, Zhongcheng, et al.
(author)
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Interface-assisted cation exchange enables high-performance perovskiteLEDs with tunable near-infrared emissions
- 2022
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In: Joule. - : Cell Press. - 2542-4351. ; 6:10, s. 2423-2436
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Journal article (peer-reviewed)abstract
- Achieving high-quality cesium-formamidinium lead iodide (CsxFA1_xPbI3) perovskites with tunable band gaps is highly desired for optoelectronic applications including solar cells and light -emit-ting diodes (LEDs). Herein, by utilizing an alkaline-interface-assisted cation-exchange method, we fabricate highly emissive CsxFA1_x PbI3 perovskite films with fine-tunable Cs-FA alloying ratio for emis-sion-tunable near-infrared (NIR) LEDs. We reveal that the deproto-nation of FA+ cations and the formation of hydrogen-bonded gels consisting of CsI and FA facilitated by the zinc oxide underneath effectively removes the Cs-FA ion-exchange barrier, promoting the formation of phase-pure CsxFA1_xPbI3 films with tunable emis-sions filling the gap between that of pure Cs-and FA-based perov-skites. The obtained NIR perovskite LEDs (PeLEDs) peaking from 715 to 780 nm simultaneously demonstrate high peak external quantum efficiencies of over 15%, maximum radiances exceeding 300 W sr_1 m_2, and high power conversion efficiencies above 10% at 100 mA cm_2, representing the best-performing LEDs based on solution-processed NIR emitters in a similar region.
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