| 1. |
- Beal, Jacob, et al.
(författare)
-
Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
-
Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 2. |
- Kristanl, Matej, et al.
(författare)
-
The Seventh Visual Object Tracking VOT2019 Challenge Results
- 2019
-
Ingår i: 2019 IEEE/CVF INTERNATIONAL CONFERENCE ON COMPUTER VISION WORKSHOPS (ICCVW). - : IEEE COMPUTER SOC. - 9781728150239 ; , s. 2206-2241
-
Konferensbidrag (refereegranskat)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. |
- Liu, Yi, et al.
(författare)
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Porous, robust, thermally stable, and flame retardant nanocellulose/polyimide separators for safe lithium-ion batteries
- 2023
-
Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 11:43, s. 23360-23369
-
Tidskriftsartikel (refereegranskat)abstract
- The safety of lithium-ion batteries (LIBs) is paramount for all users. One effective way to improve safety is incorporating heat-resistant polyimide (PI) separators, which can increase the thermal stability of batteries and minimize the risk of thermal runaway. However, preparing PI separators with both an ideal pore structure and adequate mechanical properties remains as a challenge. Here, we introduced decabromodiphenyl ethane (DBDPE) and cellulose nanofibers (CNFs) into PI and produced a hybrid separator with an outstanding pore structure and excellent mechanical properties. Aided with DBDPE, the separators attain a well-defined and uniform pore size (20 nm), while demonstrating high porosities (78%) through phase inversion processes. Owing to the addition of CNFs, the mechanical properties of the separators were significantly improved, with a tensile strength of 25.4 MPa and an elastic modulus of 550.1 MPa. Moreover, the separators demonstrate high ion conductivity (0.45 mS cm-1), excellent thermal-dimensional stability (up to 200 degrees C), remarkable flame retardancy, and outstanding electrolyte wettability. At room temperature, the batteries with the separators demonstrate comparable performance with those of polypropylene (PP) separators. However, when subjected to thermal shock treatments, the batteries with the separators outperform those with PP, showcasing their superior performance. The work introduces a novel strategy for designing high-performance separators, thereby paving the way for advancements in the fabrication of LIBs with enhanced safety features. A porous, robust, and thermally stable hybrid separator was developed to solve the dilemma between desired pore structures and mechanical properties in polyimide separators by introducing decabromodiphenyl ethane and cellulose nanofibers.
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| 4. |
- Guo, Guoyang, et al.
(författare)
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Increasing intrinsic water-use efficiency over the past 160 years does not stimulate tree growth in southeastern China
- 2018
-
Ingår i: Climate Research. - : Inter-Research Science Center. - 0936-577X .- 1616-1572. ; 76:2, s. 115-130
-
Tidskriftsartikel (refereegranskat)abstract
- © 2018 Inter-Research. Understanding the responses of tree growth and intrinsic water-use efficiency (iWUE) to anthropogenic CO2 increase and climate warming provides important benchmarks for evaluating future forest dynamics under different scenarios of warming and CO2 changes. Relative to the short period of instrumental data of the past few decades, long-term tree-ring width and stable carbon isotopic (δ13C) data are invaluable in fully comprehending their interactions during the entire industrial era, since ~1850. Here, we present a tree-ring width chronology (1856 to 2015) and Δ13C series (1876-2015) of Pinus massoniana for Yongtai county of Fujian province, in humid subtropical China, a 'green island' relative to other dry subtropical areas of the world. Tree growth was limited by precipitation of the hydrological year (previous November to current October) (r = 0.568, p < 0.001), and the stable carbon isotope discrimination (Δ13C) was strongly correlated with relative humidity in September-October (r =-0.677, p < 0.001) of the current growing season. We found that the iWUE increased by 40.9% since 1876. Specifically, we found that the ci:ca ratio decreased during the study period whereas intercellular CO2 concentration (ci) increased. The negative relationship between basal area increment (BAI) and iWUE indicated that increasing iWUE may not lead to long-term enhancement of tree growth. Our results indicated a drought-induced limitation to tree growth in response to rising CO2, and that trees may mitigate the negative effects of a decrease in water availability through a reduction in stomatal conductance.
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| 5. |
- Kristan, Matej, et al.
(författare)
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The Visual Object Tracking VOT2017 challenge results
- 2017
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Ingår i: 2017 IEEE INTERNATIONAL CONFERENCE ON COMPUTER VISION WORKSHOPS (ICCVW 2017). - : IEEE. - 9781538610343 ; , s. 1949-1972
-
Konferensbidrag (refereegranskat)abstract
- The Visual Object Tracking challenge VOT2017 is the fifth annual tracker benchmarking activity organized by the VOT initiative. Results of 51 trackers are presented; many are state-of-the-art published at major computer vision conferences or journals in recent years. The evaluation included the standard VOT and other popular methodologies and a new "real-time" experiment simulating a situation where a tracker processes images as if provided by a continuously running sensor. 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 VOT2017 goes beyond its predecessors by (i) improving the VOT public dataset and introducing a separate VOT2017 sequestered dataset, (ii) introducing a realtime tracking experiment and (iii) releasing a redesigned toolkit that supports complex experiments. The dataset, the evaluation kit and the results are publicly available at the challenge website(1).
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| 6. |
- Fang, Keyan, et al.
(författare)
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Drought variation of western Chinese Loess Plateau since 1568 and its linkages with droughts in western North America
- 2017
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Ingår i: Climate Dynamics. - : Springer Science and Business Media LLC. - 0930-7575 .- 1432-0894. ; 49:11-12, s. 3839-3850
-
Tidskriftsartikel (refereegranskat)abstract
- © 2017, Springer-Verlag Berlin Heidelberg. Understanding long-term drought variations in the past can help to evaluate ongoing and future hydroclimate change in the arid western Chinese Loess Plateau (WCLP), a region with increasing demand for water resources due to the increasing population and socioeconomic activities. Here we present a new tree-ring chronology inform the WCLP, which shows coherent interannual variations with tree-ring chronologies from 7 neighboring areas across the WCLP, suggesting a common regional climate control over tree growth. However, considerable differences are observed among their interdecadal variations, which are likely due to growth disturbances at interdecadal timescales. To deal with this issue, we use a frequency based method to develop a composite tree-ring chronology from 401 tree-ring series from these 8 sites, which shows more pronounced interdecadal variability than a chronology developed using traditional methods. The composite tree-ring chronology is used to reconstruct the annual precipitation from previous August to current July from 1568 to 2012, extending about 50 years longer than the previous longest tree-ring reconstruction from the region. The driest epoch of our reconstruction is found in the 1920s–1930s, which matches well with droughts recorded in historical documents. Over the past four centuries, a strong resemblance between drought variability in the WCLP and western North America (WNA) is evident on multidecadal timescales, but this relationship breaks down on timescales shorter than about 50 years.
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| 7. |
- Fang, Keyan, et al.
(författare)
-
Interdecadal modulation of the Atlantic Multi-decadal Oscillation (AMO) on southwest China’s temperature over the past 250 years
- 2019
-
Ingår i: Climate Dynamics. - : Springer Science and Business Media LLC. - 0930-7575 .- 1432-0894. ; 52:3/4, s. 2055-2065
-
Tidskriftsartikel (refereegranskat)abstract
- © 2018 Springer-Verlag GmbH Germany, part of Springer Nature The temperature gradient between southwestern China and Indian Ocean is one key driver of the Indian Summer Monsoon, suggesting the necessity to understand temperature variability in southwestern China. Contrary to the general warming experienced in most of China, a few regions in southwestern China have undergone a cooling trend since the 1950s. To place this cooling trend in a historical context, this study develops an Abies fabri tree-ring width chronology in the Sichuan Basin, the most populated region in southwest China. The chronology spans from 1590 to 2012, with its reliable portion from 1758 to 2012, by far the longest in the Sichuan Basin. To better extract regional climate signals encoded in tree rings with strong local disturbances, we incorporate climate signals of nearby tree-ring chronologies to generate a large-scale tree-ring chronology (LSC). The LSC shows higher correlations with temperature near the sampling site on Mount Emei and sea surface temperatures of the northern Atlantic Ocean than chronologies developed using traditional methods. The highest correlations between the LSC and temperature are found from current February to July in the Sichuan Basin for the period 1901–1950 (r = 0.70), with a sharp decrease afterwards. Interdecadal variations of the LSC match well with Atlantic Multi-decadal Oscillation reconstructions, except for the late nineteenth century and after ~ 1980s. This study provides evidence that southwest China is a transitional region both affected by the interdecadal temperature variations of the northern Atlantic and Asian areas, although their influences weakened in recent possible due to enhanced human activities.
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| 8. |
- Li, Pan, et al.
(författare)
-
Silver nano-needles : Focused optical field induced solution synthesis and application in remote-excitation nanofocusing SERS
- 2019
-
Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3364 .- 2040-3372. ; 11:5, s. 2153-2161
-
Tidskriftsartikel (refereegranskat)abstract
- Tapered metallic nanostructures that harbor surface plasmons are highly interesting for nanophotonic applications because of their waveguiding and field-focusing properties. Here, we developed a focused optical field induced solution synthesis for unique crystallized silver nano-needles. Under the focused laser spot, inhomogeneous Ag monomer concentration is created, which triggers the uniaxial growth of silver nanostructures along the radial direction with decreasing rate, forming nano-needle structures. These nano-needles are several micrometers long, with diameter attenuating from hundreds to tens of nanometers, and terminated by a sharp apex only a few nanometers in diameter. Moreover, nano-needles with atomically smooth surfaces show excellent performance for plasmonic waveguiding and unique near-field compression abilities. This nano-needle structure can be used for effective remote-excitation detection/sensing. We also demonstrate the assembling and picking up of nano-needles, which indicate potential applications in intracellular endoscopy, high resolution scanning tips, on-chip nanophotonic devices, etc.
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| 9. |
- Lin, Zhipeng, et al.
(författare)
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Electrocatalyzed direct arene alkenylations without directing groups for selective late-stage drug diversification
- 2023
-
Ingår i: Nature Communications. - 2041-1723. ; 14:1
-
Tidskriftsartikel (refereegranskat)abstract
- Electrochemistry has emerged as an increasingly viable tool in molecular synthesis. Here the authors realize electrocatalyzed C-H activations, with the aid of data science and artificial intelligence, towards selective alkenylations for late-stage drug diversifications. Electrooxidation has emerged as an increasingly viable platform in molecular syntheses that can avoid stoichiometric chemical redox agents. Despite major progress in electrochemical C-H activations, these arene functionalizations generally require directing groups to enable the C-H activation. The installation and removal of these directing groups call for additional synthesis steps, which jeopardizes the inherent efficacy of the electrochemical C-H activation approach, leading to undesired waste with reduced step and atom economy. In sharp contrast, herein we present palladium-electrochemical C-H olefinations of simple arenes devoid of exogenous directing groups. The robust electrocatalysis protocol proved amenable to a wide range of both electron-rich and electron-deficient arenes under exceedingly mild reaction conditions, avoiding chemical oxidants. This study points to an interesting approach of two electrochemical transformations for the success of outstanding levels of position-selectivities in direct olefinations of electron-rich anisoles. A physical organic parameter-based machine learning model was developed to predict position-selectivity in electrochemical C-H olefinations. Furthermore, late-stage functionalizations set the stage for the direct C-H olefinations of structurally complex pharmaceutically relevant compounds, thereby avoiding protection and directing group manipulations.
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| 10. |
- Yang, Zhilin, et al.
(författare)
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Surface enhanced Raman scattering of pyridine adsorbed on Au@Pd core/shell nanoparticles
- 2009
-
Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 130:23
-
Tidskriftsartikel (refereegranskat)abstract
- Surface enhanced Raman scattering (SERS) of pyridine adsorbed on Au@Pd core/shell nanoparticles has been investigated theoretically with quantum chemical method, generalized Mie theory and three-dimensional finite-difference time domain (3D-FDTD) method. We first studied the influence of the coated Pd on the electronic structure of Au nanoparticle, and compared the electronic structure of Au-20 cluster with that of Au10Pd10 (core/shell) cluster. Second, we studied SERS spectroscopy of pyridine on Au@Pd core/shell nanoparticles, which revealed the rate of static chemical enhancement and electromagnetic enhancement in the experimental reports. Third, the influence of the Pd shell thickness to the optical absorption of Au@Pd core/shell nanoparticles was investigated with generalized Mie theory. Fourth, we studied the influence of the shell thickness to the local electric field enhancement with 3D-FDTD method. The theoretical results reveal that the static chemical enhancement and electromagnetic enhancement are in the order of 10 and 10(3), respectively. These theoretical studies promote the deeper understanding of the electronic structure and optical absorption properties of Au@Pd, and the mechanisms for SERS of molecule adsorbed on Au@Pd.
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| 11. |
- Zhang, Wei, et al.
(författare)
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Thermal detection of surface plasmons on gold nanohole arrays
- 2012
-
Ingår i: Chinese Science Bulletin. - : Springer Science and Business Media LLC. - 1001-6538 .- 1861-9541. ; 57:1, s. 68-71
-
Tidskriftsartikel (refereegranskat)abstract
- We used a thin-film thermocouple to detect the thermal effect of surface plasmons excited in Au nanohole array structures. We found that the thermal electromotive force of Au film with periodic nanohole structures is three times greater than that of a bare Au film for 785-nm laser excitation at a given power. This effect is caused by the resonant excitation of localized surface plasmons in the nanoholes. In addition, we found that the thermal electromotive force (EMF) of the Au film with dumbbell-like nanohole arrays depends strongly on the incident polarization. The thermal EMF is the greatest when the excitation light is polarized perpendicular to the long axis of the dumbbell.
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| 12. |
- An, Di, et al.
(författare)
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Additive manufacturing and characterization of complex Al2O3 parts based on a novel stereolithography method
- 2017
-
Ingår i: International Journal of Applied Ceramic Technology. - : Wiley. - 1546-542X .- 1744-7402. ; 14:5, s. 836-844
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, we prepared Al2O3 ceramic green parts with complex geometry and architecture using an additive manufacturing process based on stereolithography. The rheological and thermal behavior of Al2O3 slurry was firstly examined and used to establish the conditions for molding and debinding. As opposed to previous researches that only focused on manufacture techniques, the sintering behavior and densification process were systematically investigated. In addition, special attentions were paid to the evolution of microstructure between green bodies and sintered parts. The results showed that debound parts were equipped with uniform particle packing and narrow pore size distribution. The dimensions of the Al2O3 parts changed anisotropically with the different processing steps. The densification process was greatly accelerated by the decrease in pore size and annihilating of interconnected pores in which significant grain growth was observed above 1450 degrees C. The sintered part also had a homogeneous microstructure and no interface between adjacent layers. High densification (relative density of 99.1%) and much desirable Vickers hardness (17.9 GPa) of Al2O3 parts were achieved at the sintering temperature of 1650 degrees C.
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| 13. |
- Bikdeli, Behnood, et al.
(författare)
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Bivalirudin Versus Heparin During PCI in NSTEMI : Individual Patient Data Meta-Analysis of Large Randomized Trials
- 2023
-
Ingår i: Circulation. - : American Heart Association. - 0009-7322 .- 1524-4539. ; 148:16, s. 1207-1219
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The benefit:risk profile of bivalirudin versus heparin anticoagulation in patients with non-ST-segment-elevation myocardial infarction undergoing percutaneous coronary intervention (PCI) is uncertain. Study-level meta-analyses lack granularity to provide conclusive answers. We sought to compare the outcomes of bivalirudin and heparin in patients with non-ST-segment-elevation myocardial infarction undergoing PCI.METHODS: We performed an individual patient data meta-analysis of patients with non-ST-segment-elevation myocardial infarction in all 5 trials that randomized >= 1000 patients with any myocardial infarction undergoing PCI to bivalirudin versus heparin (MATRIX [Minimizing Adverse Hemorrhagic Events by Transradial Access Site and Systemic Implementation of Angiox], VALIDATE-SWEDEHEART [Bivalirudin Versus Heparin in ST-Segment and Non-ST-Segment Elevation Myocardial Infarction in Patients on Modern Antiplatelet Therapy in the Swedish Web System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies Registry Trial], ISAR-REACT 4 [Intracoronary Stenting and Antithrombotic Regimen: Rapid Early Action for Coronary Treatment 4], ACUITY [Acute Catheterization and Urgent Intervention Triage Strategy], and BRIGHT [Bivalirudin in Acute Myocardial Infarction vs Heparin and GPI Plus Heparin Trial]). The primary effectiveness and safety end points were 30-day all-cause mortality and serious bleeding.RESULTS: A total of 12155 patients were randomized: 6040 to bivalirudin (52.3% with a post-PCI bivalirudin infusion), and 6115 to heparin (53.2% with planned glycoprotein IIb/IIIa inhibitor use). Thirty-day mortality was not significantly different between bivalirudin and heparin (1.2% versus 1.1%; adjusted odds ratio, 1.24 [95% CI, 0.86-1.79]; P=0.25). Cardiac mortality, reinfarction, and stent thrombosis rates were also not significantly different. Bivalirudin reduced serious bleeding (both access site-related and non-access site-related) compared with heparin (3.3% versus 5.5%; adjusted odds ratio, 0.59; 95% CI, 0.48-0.72; P<0.0001). Outcomes were consistent regardless of use of a post-PCI bivalirudin infusion or routine lycoprotein IIb/IIIa inhibitor use with heparin and during 1-year follow-up.CONCLUSIONS: In patients with non-ST-segment-elevation myocardial infarction undergoing PCI, procedural anticoagulation with bivalirudin and heparin did not result in significantly different rates of mortality or ischemic events, including stent thrombosis and reinfarction. Bivalirudin reduced serious bleeding compared with heparin arising both from the access site and nonaccess sites.
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| 14. |
- Chen, Guanying, et al.
(författare)
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(alpha-NaYbF4:Tm3+)/CaF2 Core/Shell Nanoparticles with Efficient Near-Infrared to Near-Infrared Upconversion for High-Contrast Deep Tissue Bioimaging
- 2012
-
Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 6:9, s. 8280-8287
-
Tidskriftsartikel (refereegranskat)abstract
- We describe the development of novel and biocompatible core/shell (alpha-NaYbF4:Tm3+)/CaF2 nanoparticles that exhibit highly efficient NIRin-NIROut upconversion (UC) for high contrast and deep bioimaging. When excited at similar to 980 nm, these nanoparticles emit photoluminescence (PL) peaked at similar to 800 nm. The quantum yield of this UC PL under low power density excitation (similar to 0.3 W/cm(2)) is 0.6 +/- 0.1%. This high UC PL efficiency is realized by suppressing surface quenching effects via heteroepitaxial growth of a biocompatible CaF2 shell, which results in a 35-fold increase in the intensity of UC PL from the core. Small-animal whole-body UC PL imaging with exceptional contrast (signal-to-background ratio of 310) is shown using BALB/c mice intravenously injected with aqueously dispersed nanoparticles (700 pmol/kg). High-contrast UC PL imaging of deep tissues is also demonstrated, using a nanoparticle-loaded synthetic fibrous mesh wrapped around rat femoral bone and a cuvette with nanoparticle aqueous dispersion covered with a 3.2 cm thick animal tissue (pork).
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| 15. |
- Fang, Yurui, et al.
(författare)
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Branched Silver Nanowires as Controllable Plasmon Routers
- 2010
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 10:5, s. 1950-1954
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Tidskriftsartikel (refereegranskat)abstract
- Using polarization dependent scattering spectroscopy, we investigate plasmon propagation on branched silver nanowires. By controlling the polarization of the incident laser light, the wire plasmons can be routed into different wire branches and result in light emission from the corresponding wire ends. This routing behavior is found to be strongly dependent on the wavelength of light. Thus for certain incident polarizations, light of different wavelength will be routed into different branches. The branched nanowire can thus serve as a controllable router and multiplexer in integrated plasmonic circuits.
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| 16. |
- Feng, Kent Y, et al.
(författare)
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Association Between Serum Albumin and Outcomes in Heart Failure and Secondary Mitral Regurgitation: The COAPT Trial.
- 2023
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Ingår i: European journal of heart failure. - : Wiley. - 1879-0844 .- 1388-9842.
-
Tidskriftsartikel (refereegranskat)abstract
- Low serum albumin levels are associated with poor prognosis in numerous chronic disease states but the relationship between albumin and outcomes in patients with heart failure (HF) and secondary mitral regurgitation (SMR) has not been described.The randomized COAPT trial evaluated the safety and effectiveness of transcatheter edge-to-edge repair (TEER) with the MitraClip plus guideline-directed medical therapy (GDMT) versus GDMT alone in patients with symptomatic HF and moderate-to-severe or severe SMR. Baseline serum albumin levels were measured at enrollment. Among 614 patients enrolled in COAPT, 559 (91.0%) had available baseline serum albumin levels (median 4.0 g/dL, IQR 3.7-4.2 g/dL). Patients with albumin <4.0 g/dL compared with ≥4.0 g/dL were older and more likely to have ischemic cardiomyopathy and a hospitalization within the year prior to enrollment. After multivariable adjustment, patients with albumin <4.0 g/dL had higher 4-year rates of all-cause death (63.7% vs. 47.6%; adjusted HR 1.34, 95% CI 1.02-1.74; p=0.032), but there were no significant differences in heart failure hospitalizations (HFH) or all-cause hospitalizations according to baseline serum albumin level. The relative effectiveness of TEER plus GDMT versus GDMT alone was consistent in patients with low and high albumin levels (Pinteraction = 0.19 and 0.35 for death and HFH, respectively).Low baseline serum albumin levels were independently associated with reduced 4-year survival in patients with HF and severe SMR enrolled in the COAPT trial, but not with HFH. Patients treated with TEER derived similarly robust reductions in both death and HFH regardless of baseline albumin level. This article is protected by copyright. All rights reserved.
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| 17. |
- Han, Huifeng, et al.
(författare)
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Tunable surface plasma resonance frequency in Ag core/Au shell nanoparticles system prepared by laser ablation
- 2008
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 92:2
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Tidskriftsartikel (refereegranskat)abstract
- A method for preparation of Ag core/Au shell nanoparticles with tunable surface plasma resonance (SPR) band was presented and studied. It was found that the tunable SPR band could be significantly conducted and achieved by laser ablation to Au plate in Ag colloidal solution, leading to the formation of Ag core/Au shell structure by the deposition of Au atoms on the surface of Ag nanoparticles. Dependence of the tunable shift of SPR bands on Ag core/Au shell structure was further illustrated by simulation of absorption spectra based on Mie theory, and consistent with the experimental results.
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| 18. |
- Li, Kexue, et al.
(författare)
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Directional emissions from perovskite nanocrystals thin film enabled by metasurface integration through one step spin-coating process
- 2023
-
Ingår i: Nano Research. - : Springer Science and Business Media LLC. - 1998-0124 .- 1998-0000. ; 16:5, s. 7646-7653
-
Tidskriftsartikel (refereegranskat)abstract
- Advances in thin film light-emitting devices have fueled the rapid growth of a new class of solid-state lighting devices, featuring low fabrication cost, high quantum efficiency, and broadband spectrum coverage, etc. In contrast to the conventional inorganic semiconductors that rely on lattice matched high crystalline quality substrate, solution processable thin films eliminate the dependence on the substrate, which is highly desired for the ease and versatility of integrations with foreign medium. By taking this advantage, this work developed an ultracompact solution to control the directionality of thin film emitters using integrated dielectric metasurface through one step spin-coating process. As a proof of concept, directional emissions from perovskite nanocrystal thin film, including collimated light emissions and two-dimensional beam steering, are experimentally demonstrated. Notably, our approach, where light emitters were integrated on the back side of substrate after the fabrication of metasurface, judiciously avoids any potential degradation of material optical quality caused by the multi-step nanofabrication. Therefore, it can serve as a generalized scheme to engage the advantageous properties of dielectric metasurface, including the compactness, high efficiency, and beam controllability with the emerging thin film light-emitting diodes (LEDs), which is applicable to a wide range of solution processable materials, including organic light-emitting diodes, quantum-dot light emitting diodes, polymer LEDs, and perovskite LEDs, opening up new pathways to develop low-cost and ultra-compact solid state light sources with versatile beams characteristics. [Figure not available: see fulltext.].
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| 19. |
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| 20. |
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| 21. |
- Li, Zhipeng, et al.
(författare)
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Correlation between Incident and Emission Polarization in Nanowire Surface Plasmon Waveguides
- 2010
-
Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 10:5, s. 1831-1835
-
Tidskriftsartikel (refereegranskat)abstract
- Nanowire plasmons can be launched by illumination at one terminus of the nanowire and emission can be detected at the other end of the wire. Using polarization dependent dark-held scattering spectroscopy, we measure how the polarization of the emitted light depends on the polarization of the incident light. We observe that the shape of the nanowire termination plays an important role in determining this polarization change. Depending on termination shape, a nanowire can serve as either a polarization-maintaining waveguide, or as a polarization-rotating, nanoscale half-wave plate. The understanding of how plasmonic waveguiding influence the polarization of the guided light is important for optimizing the structure of integrated plasmonic devices
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| 22. |
- Li, Zhipeng, et al.
(författare)
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Directional Light Emission from Propagating Surface Plasmons of Silver Nanowires.
- 2009
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 9:Online September 21, 2009, s. 4383-4386
-
Tidskriftsartikel (refereegranskat)abstract
- Thin metallic nanowires are highly promising candidates for plasmonic waveguides in photonic and electronic devices. We have observed that light from the end of a silver nanowire, following excitation of plasmons at the other end of the wire, is emitted in a cone of angles peaking at nominally 45-60 degrees from the nanowire axis, with virtually no light emitted along the direction of the nanowire. This surprising characteristic can be explained in a simple picture invoking Fabry-Perot resonances of the forward- and back-propagating plasmons on the nanowire. This strongly angular-dependent emission is a critical property that must be considered when designing coupled nanowire-based photonic devices and systems.
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| 23. |
- Li, Zhipeng, et al.
(författare)
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Effect of a proximal substrate on plasmon propagation in silver nanowires
- 2010
-
Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 82:24
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate how the properties of a nearby substrate modify the excitation and propagation of plasmons in subwavelength silver wires. With decreasing nanowire-substrate separation, the in-coupling efficiency shows strongly oscillatory behavior due to coherent interference. The plasmon damping increases with decreasing separation due to an increased coupling of the nanowire plasmons to the photonic modes of the substrate.
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| 24. |
- Li, Zhipeng, et al.
(författare)
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Electromagnetic energy flow near metal nanoparticles - II: Algorithms for the calculation of the light scattering of multi-spheres and photon energy transport via linear chains of Ag nanoparticles
- 2007
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Ingår i: Journal of Quantitative Spectroscopy & Radiative Transfer. - : Elsevier BV. - 0022-4073. ; 103:2, s. 394-401
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Tidskriftsartikel (refereegranskat)abstract
- We present a new algorithm to calculate the near-field distribution of scattered light of multiple nanospheres based on recursive order-of-scattering (OS) and the matrix inversion approaches, which avoids the divergent problem encountered in origin OS method at the resonance condition. Using this method, we investigate the light-transport properties of linear chains of Ag nanospheres. We found a maximum 3 dB damping length of 1.4 mu m of the light propagation when the first sphere of the linear Ag spheres with the radius R = 25 nm was illuminated. The optimal configurations that favor the photon energy transport are investigated as well. (c) 2006 Elsevier Ltd. All rights reserved.
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| 25. |
- Li, Zhipeng, et al.
(författare)
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Multiple-Particle Nanoantennas for Enormous Enhancement and Polarization Control of Light Emission.
- 2009
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-086X .- 1936-0851. ; 3:3, s. 637-642
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the light emission from dipolar emitters located within nanoparticle antennas. It is found that the enormous emission enhancement can reach nearly a million fold. For multinanoparticle antennas, the polarization of the emissions strongly depends on the geometry of the antennas, the emitted wavelengths, and the dielectric functions of surrounding media. It is shown that a polarization nanorotator, which modulates the emission polarization on the nanometer scale, can be readily realized by varying either the geometry or surrounding media of nanoparticle antennas.
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| 26. |
- Li, Zhipeng, et al.
(författare)
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Nanoantenna effect of surface-enhanced Raman scattering : managing light with plasmons at the nanometer scale
- 2016
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Ingår i: Advances in Physics: X. - : Informa UK Limited. - 2374-6149. ; 1:3, s. 492-521
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Forskningsöversikt (refereegranskat)abstract
- Manipulating light on the nanometer scale is a challenging topic not only from a fundamental point of view, but also for applications aiming toward the design of miniature optical devices. Nanoplasmonics is a rapidly emerging branch of photonics, which offers variable means to manipulate light using surface plasmon excitations on metal nanostructures. As a spectroscopic phenomenon discovered nearly 40 years ago, surface-enhanced Raman scattering (SERS) has been an active topic of fundamental and applied researches. The dominating electromagnetic enhancement in SERS is caused by surface plasmon resonances. This is a typical example of manipulating light intensity with plasmons. Here, we will review the recent SERS studies related to nanoantenna effects on different metal nanostructures based on electromagnetic enhancement. Three aspects will be the focus in this paper: (1) the coupled nanostructures which act as receiving and emitting antenna that can generate enormous SERS enhancement ~E4 even enough for single molecule SERS. (2) The polarization of SERS at the single molecule limit, including the linear and circular polarizations can be manipulated using designed asymmetric antennas. Such an effect can make the traditional 1/2 and 1/4 wave plates miniaturized to the nanometer scale. (3) Combining nanoantenna and waveguiding effects, remote excitation of SERS can be realized, which may open a new area of single molecule SERS on nanophotonic circuits.
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| 27. |
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| 28. |
- Lou, Xiaolong, et al.
(författare)
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An Empirical Evaluation on Arm Fatigue in Free Hand Interaction and Guidelines for Designing Natural User Interfaces in VR
- 2020
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Ingår i: Virtual, Augmented and Mixed Reality. Design and Interaction. - Cham : Springer. - 9783030496944 - 9783030496951 ; , s. 313-324
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Konferensbidrag (refereegranskat)abstract
- This research had a systematic study on arm fatigue issue in free hand interaction in VR environment and explored how arm fatigue influenced free hand interaction accuracy. A specifically designed target-acquisition experiment was conducted with 24 volunteered participants (7 left-handedness, 17 right-handedness) recruited. The experiment results indicated that (1) arm fatigue resulted in short durations of hand operation, or frequent alternations of operating hand. The user’s dominant hand had a more durable operation than the non-dominant one; (2) hand operate position had a significant effect on arm fatigue level, a bent arm posture was found to be more labor-saving than an extended arm posture, (3) hand operation at a higher position (e.g., at the head height) perceived arm fatigue more easily than that at a lower position (e.g., at the waist height); and (4) arm fatigue impact hand interaction accuracy negatively.
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| 29. |
- Ludwig, Sebastian, et al.
(författare)
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Transcatheter Mitral Valve Replacement versus Medical Therapy for Secondary Mitral Regurgitation: A Propensity Score-Matched Comparison.
- 2023
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Ingår i: Circulation. Cardiovascular interventions. - 1941-7632. ; 16:6
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Tidskriftsartikel (refereegranskat)abstract
- Background: Transcatheter mitral valve replacement (TMVR) is an emerging therapeutic alternative for patients with secondary mitral regurgitation (MR). Outcomes of TMVR versus guideline-directed medical therapy (GDMT) have not been investigated for this population. This study aimed to compare clinical outcomes of patients with secondary MR undergoing TMVR versus GDMT alone. Methods: The CHOICE-MI registry included patients with MR undergoing TMVR using dedicated devices. Patients with MR etiologies other than secondary MR were excluded. Patients treated with GDMT alone were derived from the control arm of the COAPT trial. We compared outcomes between the TMVR and GDMT groups, using propensity score (PS)-matching to adjust for baseline differences. Results: After PS-matching, 97 patient pairs undergoing TMVR (72.9±8.7 years, 60.8% male, transapical access 91.8%) versus GDMT (73.1±11.0 years, 59.8% male) were compared. At 1 and 2 years, residual MR was ≤1+ in all patients of the TMVR group compared to 6.9% and 7.7%, respectively, in those receiving GDMT alone (both p<0.001). The 2-year rate of HF hospitalization was significantly lower in the TMVR group (32.8% vs. 54.4%, HR 0.59, 95% CI 0.35-0.99; p=0.04). Among survivors, a higher proportion of patients were in NYHA functional class I or II in the TMVR group at 1 year (78.2% vs. 59.7%, p=0.03) and at 2 years (77.8% vs. 53.2%, p=0.09). Two-year mortality was similar in the two groups (TMVR vs. GDMT, 36.8% vs. 40.8%, HR 1.01, 95% CI 0.62-1.64; p=0.98). Conclusions: In this observational comparison, over 2-year follow-up, TMVR using mostly transapical devices in patients with secondary MR was associated with significant reduction of MR, symptomatic improvement, less frequent hospitalizations for HF and similar mortality compared with GDMT.
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| 30. |
- Min, Sugi, et al.
(författare)
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Clinical characteristics and outcomes of patients requiring prolonged mechanical circulatory support after high-risk percutaneous coronary intervention
- 2024
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Ingår i: EuroIntervention : journal of EuroPCR in collaboration with the Working Group on Interventional Cardiology of the European Society of Cardiology. - 1969-6213. ; 20:2
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: There are limited data on the clinical characteristics and outcomes of patients who require prolonged mechanical circulatory support (MCS) after Impella-supported high-risk percutaneous coronary intervention (HR-PCI). AIMS: The aim of this study is to describe the contemporary clinical characteristics, outcomes, and predictors associated with prolonged MCS support after assisted HR-PCI. METHODS: Patients enrolled in the prospective, multicentre, clinical endpoint-adjudicated PROTECT III study who had undergone HR-PCI using Impella were evaluated. Patient and procedural characteristics and outcomes for those who received prolonged MCS beyond the duration of their index procedure were compared to those in whom MCS was successfully weaned and explanted at the conclusion of the index PCI. RESULTS: Among 1,155 patients who underwent HR-PCI with Impella between 2017 and 2020 and had sufficient data to confirm theduration of Impella support, 16.5% received prolonged MCS (mean duration 25.2±31.1 hours compared with 1.8±5.8 hours for those who only received intraprocedural MCS). Patients receiving prolonged support presented with more urgent indications (e.g., acute coronary syndromes [ACS], lower ejection fraction [EF], elevated baseline heart rate and lower systolic blood pressure). Use of the Impella CP, intraprocedural complications, periprocedural complications and in-hospital mortality were all more common amongst the prolonged MCS group. Prolonged MCS was associated with increased rates of major adverse cardiovascular and cerebrovascular events, cardiovascular death, and all-cause mortality at 90-day follow-up. CONCLUSIONS: Patients receiving prolonged MCS after Impella-supported HR-PCI presented with more ACS, reduced EF and less favourable haemodynamics. Additionally, they were more likely to experience intraprocedural and periprocedural complications as well as increased in-hospital and post-discharge mortality.
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| 31. |
- Shah, Tayyab, et al.
(författare)
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Sex Differences in pLVAD-Assisted High-Risk Percutaneous Coronary Intervention: Insights From the PROTECT III Study.
- 2023
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Ingår i: JACC. Cardiovascular interventions. - 1876-7605. ; 16:14, s. 1721-1729
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Tidskriftsartikel (refereegranskat)abstract
- Prior studies have found that female patients have worse outcomes following high-risk percutaneous coronary intervention (HRPCI).The authors sought to evaluate sex-based differences in patient and procedural characteristics, clinical outcomes, and safety of Impella-supported HRPCI in the PROTECT III study.We evaluated sex-based differences in the PROTECT III study; a prospective, multicenter, observational study of patients undergoing Impella-supported HRPCI. The primary outcome was 90-day major adverse cardiac and cerebrovascular events (MACCE)-the composite of all-cause death, myocardial infarction, stroke/transient ischemic attack, and repeat revascularization.From March 2017 to March 2020, 1,237 patients (27% female) were enrolled. Female patients were older, more often Black, more often anemic, and had more prior strokes and worse renal function, but higher ejection fractions compared to male patients. Preprocedural SYNTAX score was similar between sexes (28.0 ± 12.3). Female patients were more likely to present with acute myocardial infarction (40.7% vs 33.2%; P = 0.02) and more often had femoral access used for PCI and nonfemoral access used for Impella device implantation. Female patients had higher rates of immediate PCI-related coronary complications (4.2% vs 2.1%; P = 0.004) and a greater drop in SYNTAX score post-procedure (-22.6 vs -21.0; P = 0.04). There were no sex differences in 90-day MACCE, vascular complications requiring surgery, major bleeding, or acute limb ischemia. After adjustment using propensity matching and multivariable regression, immediate PCI-related complications was the only safety or clinical outcome that was significantly different by sex.In this study, rates of 90-day MACCE compared favorably to prior cohorts of HRPCI patients and there was no significant sex differences. (The PROTECT III Study is a substudy of The Global cVAD Study [cVAD]; NCT04136392).
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| 32. |
- Shegai, Timur, et al.
(författare)
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Managing light polarization via plasmon-molecule interactions within an asymmetric metal nanoparticle trimer
- 2008
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Ingår i: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 105:43, s. 16448-16453
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Tidskriftsartikel (refereegranskat)abstract
- The interaction of light with metal nanoparticles leads to novel phenomena mediated by surface plasmon excitations. In this article we use single molecules to characterize the interaction of surface plasmons with light, and show that such interaction can strongly modulate the polarization of the emitted light. The simplest nanostructures that enable such polarization modulation are asymmetric silver nanocrystal trimers, where individual Raman scattering molecules are located in the gap between two of the nanoparticles. The third particle breaks the dipolar symmetry of the two-particle junction, generating a wavelength-dependent polarization pattern. Indeed, the scattered light becomes elliptically polarized and its intensity pattern is rotated in the presence of the third particle. We use a combination of spectroscopic observations on single molecules, scanning electron microscope imaging, and generalized Mie theory calculations to provide a full picture of the effect of particles on the polarization of the emitted light. Furthermore, our theoretical analysis allows us to show that the observed phenomenon is very sensitive to the size of the trimer particles and their relative position, suggesting future means for precise control of light polarization on the nanoscale.
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| 33. |
- Sun, Huiliang, et al.
(författare)
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A Narrow-Bandgap n-Type Polymer with an Acceptor-Acceptor Backbone Enabling Efficient All-Polymer Solar Cells
- 2020
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Ingår i: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095. ; 32
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Tidskriftsartikel (refereegranskat)abstract
- Narrow-bandgap polymer semiconductors are essential for advancing the development of organic solar cells. Here, a new narrow-bandgap polymer acceptor L14, featuring an acceptor-acceptor (A-A) type backbone, is synthesized by copolymerizing a dibrominated fused-ring electron acceptor (FREA) with distannylated bithiophene imide. Combining the advantages of both the FREA and the A-A polymer, L14 not only shows a narrow bandgap and high absorption coefficient, but also low-lying frontier molecular orbital (FMO) levels. Such FMO levels yield improved electron transfer character, but unexpectedly, without sacrificing open-circuit voltage (V-oc), which is attributed to a small nonradiative recombination loss (E-loss,E-nr) of 0.22 eV. Benefiting from the improved photocurrent along with the high fill factor andV(oc), an excellent efficiency of 14.3% is achieved, which is among the highest values for all-polymer solar cells (all-PSCs). The results demonstrate the superiority of narrow-bandgap A-A type polymers for improving all-PSC performance and pave a way toward developing high-performance polymer acceptors for all-PSCs.
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| 34. |
- Sun, Mengtao, et al.
(författare)
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Direct visual evidence for chemical mechanisms of SERRS via charge transfer in Au-20-pyrazine-Au-20 junction
- 2009
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Ingår i: Journal of Raman Spectroscopy. - : Wiley. - 1097-4555 .- 0377-0486. ; 40:12, s. 1942-1948
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Tidskriftsartikel (refereegranskat)abstract
- The essence of the chemical mechanism for surface-enhanced resonance Raman scattering (SERRS) is the charge transfer (CT) between the metal and the molecule at the resonant electronic transition, which results in the mode-selective enhancement in the SERRS spectrum. The site-orientated CT can directly interpret the mode-selective chemical enhancement in SERRS. However, it is a great challenge to intutively visualize the orientation and site of the CT. In this paper, for the pyrazine-Au-2 complex, a three-dimensional [3D) cubic representation is built to provide direct visual evidence for chemical mechanisms of SERRS via CT from the Au-2 cluster to pyrazine at the resonant electronic transition. The relationship between the mode-selective enhancements in SERRS and the site-orientated CT was clearly revealed. The intracluster excitation (analog of plasmon excitation in large naonoparticles) was also visualized by the 3D cubic presentation, which provided the direct evidence of local electromagnetic field enhancement of SERRS. To study the quantum size effect and the coupling effect of the nanoparticles, the photoexcitation mechanisms of the Au-20 - pyrazine complex and the Au-20 - pyrazine - Au-20 junction were also investigated. The tunneling charge transfer from one Au-20 cluster to another Au-20 cluster outside the pyrazine in Au-20 - pyrazine - Au-20 junction was also revealed visually. The calculated normalized extinction spectra of Au nanoparticles using the generalized Mie theory reveal that the resonance peak is red-shifted due to the coupling between particles. Copyright (C) 2009 John Wiley & Sons, Ltd.
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| 35. |
- Sun, Mengtao, et al.
(författare)
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Direct visual evidence for the chemical mechanism of surface-enhanced resonance Raman scattering via charge transfer: (II) Binding-site and quantum-size effects
- 2009
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Ingår i: Journal of Raman Spectroscopy. - : Wiley. - 1097-4555 .- 0377-0486. ; 40:9, s. 1172-1177
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Tidskriftsartikel (refereegranskat)abstract
- We describe quantum-size and binding-site effects on the chemical and local field enhancement mechanisms of surface-enhanced resonance Raman scattering (SERRS), in which the pyridine molecule is adsorbed on one of the vertices of the Ag-20 tetrahedron. We first investigated the influence of the binding site on normal Raman scattering (NRS) and excited state properties of optical absorption spectroscopy. Second, we investigated the quantum-size effect on the electromagnetic (EM) and chemical mechanism from 300 to 1000 nm with charge difference density. It is found that the strong absorption at around 350 nm is mainly the charge transfer (CT) excitation (CT between the molecule and the silver cluster) for large clusters, which is the direct evidence for the chemical enhancement mechanism for SERRS; for a small cluster the strong absorption around 350 nm is mainly intracluster excitation, which is the direct evidence for the EM enhancement mechanism. This conclusion is further confirmed with the general Mie theory. The plasmon peak in EM enhancement will be red-shifted with the increase of cluster size. The influence of the binding site and quantum-size effects on NRS, as well as chemical and EM enhancement mechanisms on SERRS, is significant. Copyright (C) 2009 John Wiley & Sons, Ltd.
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| 36. |
- Sun, Mengtao, et al.
(författare)
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Remote Excitation Polarization-Dependent Surface Photochemical Reaction by Plasmonic Waveguide
- 2011
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Ingår i: Plasmonics. - : Springer Science and Business Media LLC. - 1557-1963 .- 1557-1955. ; 6:4, s. 681-687
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Tidskriftsartikel (refereegranskat)abstract
- For the first time, we report remote excitation polarization-dependent surface photochemical reaction by plasmonic waveguide. Remote excitation polarization-dependent surface-enhanced Raman scattering (SERS) spectra indicate a surface photochemical reaction that p-aminothiophenol is converted to p,p'-dimercaptoazobenzene (DMAB) induced by the plasmonic waveguide. Surface plasmon polaritons generated at the end of a silver nanowire can propagate efficiently along the nanowire, and be coupled by nanoparticles near the nanowire as a nanoantenna. Massive electromagnetic enhancement is generated in the nanogap between the nanowire and the nanoparticles. The remote excitation polarization-dependent SERS spectra can be obtained experimentally in the nanogaps; furthermore, the remote excitation polarization-dependent SERS spectra of DMAB reveal the occurrence of this surface catalytic reaction. Theoretical simulations using finite-difference time-domain methods strongly support our experimental results.
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| 37. |
- Tong, Lianming, et al.
(författare)
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Optical properties of single coupled plasmonic nanoparticles
- 2013
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Ingår i: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9084 .- 1463-9076. ; 15:12, s. 4100-4109
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Tidskriftsartikel (refereegranskat)abstract
- The electromagnetic (EM) coupling between metal nanoparticles (NPs) is of essential importance in nanoplasmonic systems, leading to a variety of fundamental studies and practical applications. The successive investigations in this field not only bring forward surprising optical effects in nanoplasmonics, but also allow revealing other novel chemical/physical properties in relevant systems. In this article, we will discuss the EM coupling in four types of typical plasmonic nanostructures, i.e., single aggregated metal NPs, asymmetric metal NPs dimers, nano-manipulated metal NPs and supported metal NPs on a substrate, and outlook the corresponding impacts in understanding physics and extending applications.
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| 38. |
- Tong, Lianming, et al.
(författare)
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Single gold-nanoparticle-enhanced Raman scattering of individual single-walled carbon nanotubes via atomic force microscope manipulation
- 2008
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 112:18, s. 7119-7123
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Tidskriftsartikel (refereegranskat)abstract
- Investigating the electric field distribution around individual metallic nanoparticles is of significant importance for the understanding of the electromagnetic (EM) mechanism of surface-enhanced Raman scattering (SERS). We report single gold-nanoparticle-enhanced Raman scattering of individual single-walled carbon nanotubes (SWNTs) by atomic force microscope (AFM) manipulation. The distance between the gold nanoparticle (GNP) and the SWNT can be controlled by pushing the GNP with an AFM tip. The Raman signals increase when a single GNP is moved close to an individual SWNT, and the corresponding polarization dependence to the incident laser excitation at each GNP/SWNT distance is studied. The agreement of the experimental results with the theoretical model described in this paper suggests a rational modification of the EM enhancement model of SERS for one-dimensional "molecules", like nanotubes.
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| 39. |
- Wang, Benfei, et al.
(författare)
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Higher Order Sliding Mode Observer Based Fast Composite Backstepping Control for HESS in DC Microgrids
- 2024
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Ingår i: IEEE Transactions on Sustainable Energy. - : Institute of Electrical and Electronics Engineers (IEEE). - 1949-3029 .- 1949-3037. ; 15:3, s. 1627-1639
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Tidskriftsartikel (refereegranskat)abstract
- Hybrid energy storage system (HESS) is effective to compensate for fluctuation power in renewables and fast fluctuation loads in DC microgrids. To regulate DC bus voltage, a power management strategy is an essential issue. In the meantime, the increasing integration of constant power loads (CPLs) in DC microgrids brings great challenges to stable operation due to their negative incremental impedance. In this paper, a fast composite backstepping control (FBC) method is proposed for the HESS to achieve faster dynamics, smaller voltage variations, and large-signal stabilization. In the FBC method, a higher order sliding mode observer (HOSMO) is adopted to estimate the coupled disturbances. Furthermore, the FBC method is integrated with the droop control; so that the FBC-based decentralized power allocation (FBC-DPA) strategy for HESS in DC microgrids is developed. The proposed FBC method is designed based on the Lyapunov function to ensure its stability. Moreover, the design guidelines are provided to facilitate the application of the proposed method. Both simulation and experimental studies under different operating scenarios show that the proposed method achieves faster voltage recovery and smaller voltage variations than the conventional backstepping control method.
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| 40. |
- Wang, Lei, et al.
(författare)
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Intensified variability of the El Niño–Southern Oscillation enhances its modulations on tree growths in southeastern China over the past 218 years
- 2018
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Ingår i: International Journal of Climatology. - : Wiley. - 0899-8418 .- 1097-0088. ; 38:14, s. 5293-5304
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Tidskriftsartikel (refereegranskat)abstract
- © 2018 Royal Meteorological Society Lack of long-term tree-ring records in the core regions of the Asian summer monsoon in southeastern China limits our ability of evaluating the current climate change in a historical context. In this study, we developed the first 218-year tree-ring chronology (1798–2015) of Pinus massoniana in Zhangping area, Fujian Province, humid subtropical China. This chronology is positively correlated with winter–spring (January–March) temperature (r = 0.359, p <.01) and summer (July–September) precipitation (r = 0.351, p <.01). Although the correlations between our tree rings with sea surface temperatures (SSTs) are not very high, the correlation pattern is very close to the correlation pattern with the El Niño–Southern Oscillation variability (ENSO). These suggest that the ENSO could be the major large-scale regulator on the growth of our tree rings. The strength of the correlations between our tree rings and the ENSO (r = 0.30, N = 66) matches closely with the ENSO variability during 1950–2015. The modulations of the ENSO on regional tree growth have been the most conspicuous since the 1950s, which corresponds to its enhanced inter-annual variability. The extreme growth anomalies match quite well with the extreme years of the moisture-sensitive chronologies. The dry epoch from 1935 to 1958 is the most severe long-lasting drought in our tree rings, which is a widely distributed pattern in southeastern China and is likely modulated by the La Niña-like modes in that period.
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| 41. |
- Wang, Wei, et al.
(författare)
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Ag@SiO2 Core-Shell Nanoparticles for Probing Spatial Distribution of Electromagnetic Field Enhancement via Surface-Enhanced Raman Scattering
- 2009
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-086X .- 1936-0851. ; 3:11, s. 3493-3496
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Tidskriftsartikel (refereegranskat)abstract
- We show that the spatial distribution of the electromagnetic (EM) field enhancement can be probed directly via dynamic evolution of surface-enhanced Raman scattering (SERS) of rhodamine 6G (R6G) molecules as they diffuse into Ag@SiO2 core-shell nanoparticles. The porous silica shell limits the diffusion of R6G molecules toward Inner Ag cores, thereby allowing direct observation and quantification of the spatial distribution of SERS enhancement as molecules migrate from the low to high EM fields inside the dielectric silica shell. Our experimental evidence is validated by the generalized Mie theory, and the approach can potentially offer a novel platform for further investigating the site and spatial distribution of the EM fields and the EM versus chemical enhancement of SERS due to molecular confinement within the Ag@SiO2 nanoshell.
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| 42. |
- Wei, Hong, et al.
(författare)
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Quantum Dot-Based Local Field Imaging Reveals Plasmon-Based Interferometric Logic in Silver Nanowire Networks
- 2011
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 11:2, s. 471-475
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Tidskriftsartikel (refereegranskat)abstract
- We show that the local electric field distribution of propagating plasmons along silver nanowires can be imaged by coating the nanowires with a layer of quantum dots, held off the surface of the nanowire by a nanoscale dielectric spacer layer. In simple networks of silver nanowires with two optical inputs, control of the optical polarization and phase of the input fields directs the guided waves to a specific nanowire output. The QD-luminescent images of these structures reveal that a complete family of phase-dependent, interferometric logic functions can be performed on these simple networks. These results show the potential for plasmonic waveguides to support compact interferometric logic operations.
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| 43. |
- Wei, Ting, et al.
(författare)
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Developed and developing world responsibilities for historical climate change and CO2 mitigation
- 2012
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 109:32, s. 12911-12915
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Tidskriftsartikel (refereegranskat)abstract
- At the United Nations Framework Convention on Climate Change Conference in Cancun, in November 2010, the Heads of State reached an agreement on the aim of limiting the global temperature rise to 2 degrees C relative to preindustrial levels. They recognized that long-term future warming is primarily constrained by cumulative anthropogenic greenhouse gas emissions, that deep cuts in global emissions are required, and that action based on equity must be taken to meet this objective. However, negotiations on emission reduction among countries are increasingly fraught with difficulty, partly because of arguments about the responsibility for the ongoing temperature rise. Simulations with two earth-system models (NCAR/CESM and BNU-ESM) demonstrate that developed countries had contributed about 60-80%, developing countries about 20-40%, to the global temperature rise, upper ocean warming, and sea-ice reduction by 2005. Enacting pledges made at Cancun with continuation to 2100 leads to a reduction in global temperature rise relative to business as usual with a 1/3-2/3 (CESM 33-67%, BNU-ESM 35-65%) contribution from developed and developing countries, respectively. To prevent a temperature rise by 2 degrees C or more in 2100, it is necessary to fill the gap with more ambitious mitigation efforts.
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