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Anisotropic nano-scale resolution in 3D Bragg coherent diffraction imaging
摘要： We demonstrate that the resolution of three-dimensional (3D) real-space images obtained from Bragg coherent x-ray diffraction measurements is direction dependent. We propose and demonstrate the effectiveness of a metric to determine the spatial resolution of images that accounts for the directional dependence. The measured direction dependent resolution of (cid:2)4–9 nm is higher than the best previously obtained 3D measurements. Finally, we quantify the relationship between the resolution of recovered real-space images and dosage and discuss its implications in the light of next generation synchrotrons.
关键词： synchrotrons,resolution,Bragg coherent x-ray diffraction imaging,dosage,direction dependent
更新于2025-09-23 15:21:21
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Gate Conduction Mechanisms and Lifetime Modeling of p-Gate AlGaN/GaN High-Electron-Mobility Transistors
摘要： The gate conduction mechanisms in p-gallium nitride (GaN)/AlGaN/GaN enhancement mode transistors are investigated using temperature-dependent dc gate current measurements. In each of the different gate voltage regions, a physical model is proposed and compared to experiment. At negative gate bias, Poole–Frenkel emission (PFE) occurs within the passivation dielectric from gate to source. At positive gate bias, the p-GaN/AlGaN/GaN “p-i-n” diode is in forward operation mode, and the gate current is limited by hole supply at the Schottky contact. At low gate voltages, the current is governed by thermionic emission with Schottky barrier lowering in dislocation lines. Increasing the gate voltage and temperature results in thermally assisted tunneling (TAT) across the same barrier. An improved gate process reduces the gate current in the positive gate bias region and eliminates the onset of TAT. However, at high positive gate bias, a sharp increase in current is observed originating from PFE at the metal/p-GaN interface. Using the extracted conduction mechanisms for both devices, accurate lifetime models are constructed. The device fabricated with the novel gate process exhibits a maximum gate voltage of 7.2 V at t1% = 10 years.
关键词： time-dependent breakdown (TDB),p-GaN gate,high-electron-mobility transistor (HEMT),enhancement mode,gallium nitride (GaN),Conduction mechanism
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Field emission patterns from carbon nanotubes calculated by time-dependent density functional theory
摘要： We calculated the field emission patterns of various types of carbon nanotubes (CNTs). Regarding the near field regime, emission patterns of CNTs and hydrogen terminated CNTs (H-CNTs) well corresponds to the atoms located in the tube tip. We also found different focusing features; a focused-type and an unfocused-type. The beams from armchair (5,5) and (6,6) types are focused, while the beam from zigzag (9,0) types are unfocused.
关键词： field emission,carbon nanotubes,emission pattern,time dependent density functional theory,first principle calculation,ab initio calculation
更新于2025-09-23 15:21:21
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Numerical stability of time-dependent coupled-cluster methods for many-electron dynamics in intense laser pulses
摘要： We investigate the numerical stability of time-dependent coupled-cluster theory for many-electron dynamics in intense laser pulses, comparing two coupled-cluster formulations with full configuration interaction theory. Our numerical experiments show that orbital-adaptive time-dependent coupled-cluster doubles (OATDCCD) theory offers significantly improved stability compared with the conventional Hartree-Fock-based time-dependent coupled-cluster singles-and-doubles (TDCCSD) formulation. The improved stability stems from greatly reduced oscillations in the doubles amplitudes, which, in turn, can be traced to the dynamic biorthonormal reference determinants of OATDCCD theory. As long as these are good approximations to the Brueckner determinant, OATDCCD theory is numerically stable. We propose the reference weight as a diagnostic quantity to identify situations where the TDCCSD and OATDCCD theories become unstable.
关键词： time-dependent coupled-cluster theory,OATDCCD,Brueckner determinant,TDCCSD,intense laser pulses,numerical stability,many-electron dynamics
更新于2025-09-23 15:21:01
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New Unsymmetrical Bisacridine Derivatives Noncovalently Attached to Quaternary Quantum Dots Improve Cancer Therapy by Enhancing Cytotoxicity toward Cancer Cells and Protecting Normal Cells
摘要： The use of nanoparticles for the controlled drug delivery to cells has emerged as a good alternative to traditional systemic delivery. Quantum dots (QDs) offer potentially invaluable societal benefits such as drug targeting and in vivo biomedical imaging. In contrast, QDs may also pose risks to human health and the environment under certain conditions. Here, we demonstrated that a unique combination of nanocrystals core components (Ag-In-Zn-S) would eliminate the toxicity problem and increase their biomedical applications. The alloyed quaternary nanocrystals Ag-In-Zn-S (QDgreen, Ag1.0In1.2Zn5.6S9.4; QDred, Ag1.0In1.0Zn1.0S3.5) were used to transport new unsymmetrical bisacridine derivatives (UAs, C-2028 and C-2045) into lung H460 and colon HCT116 cancer cells for improving the cytotoxic and antitumor action of these compounds. UAs were coupled with QD through physical adsorption. The obtained results clearly indicate that the synthesized nanoconjugates exhibited higher cytotoxic activity than unbound compounds, especially toward lung H460 cancer cells. Importantly, unsymmetrical bisacridines noncovalently attached to QD strongly protect normal cells from the drug action. It is worth pointing out that QDgreen or QDred without UAs did not influence the growth of cancer and normal cells, which is consistent with in vivo results. In noncellular systems, at pH 5.5 and 4.0, which relates to the conditions of endosomes and lysosomes, the UAs were released from QD-UAs nanoconjugates. An increase of total lysosomes content was observed in H460 cells treated with QDs-UAs which can affect the release of the UAs from the conjugates. Moreover, confocal laser scanning microscopy analyses revealed that QD-UAs nanoconjugates enter H460 cells more efficiently than to HCT116 and normal cells, which may be the reason for their higher cytotoxicity against lung cancer. Summarizing, the noncovalent attachment of UAs to QDs increases the therapeutic efficiency of UAs by improving cytotoxicity toward lung H460 cancer cells and having protecting effects on normal cells.
关键词： lung and colon cancer cells,unsymmetrical bisacridine derivatives,drug-carrier degradation pathway,pH-dependent release,cellular uptake,in vivo antitumor efficacy,Ag-In-Zn-S nanocrystals,cytotoxic activity
更新于2025-09-23 15:21:01
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Osmium sensitizer with enhanced spin-orbit coupling for panchromatic dye-sensitized solar cells
摘要： Low-lying triplet metal-to-ligand charge transfer (3MLCT) transitions of osmium complexes induced by spin-orbit coupling (SOC) is promising to extend photocurrent response when applied to dye-sensitized solar cells. In this study, we present a newly designed osmium complex (coded CYC-33O), incorporating a 2-thiohexyl-3,4-ethylenedioxythiophene functionalized bipyridyl ancillary ligand to red-shift the absorption and enhance the absorbance of both singlet and triplet MLCT transitions. Time-dependent density functional theory (TDDFT) calculations clearly signify the reinforced 1MLCT and 3MLCT transitions of CYC-33O mainly originate from osmium to 4,4',4"-tricarboxy-2,2':6',2"-terpyridine anchoring ligand, advantaging the heterogeneous electron transfer between CYC-33O and TiO2. The device sensitized with CYC-33O exhibits the panchromatic conversion beyond 1000 nm, yielding the photocurrent density of 19.38 mA cm–2 which is much higher than those of the cells based on the ruthenium analogue (CYC-33R) and model osmium complex (Os-3) sensitizers.
关键词： dye-sensitized solar cell,triplet metal-to-ligand charge transfer (3MLCT),ruthenium complex,spin-orbit coupling (SOC),osmium complex,time-dependent density functional theory (TDDFT)
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Inserting a Low-Refractive-Index Dielectric Rear Reflector into PERC Cells: Challenges and Opportunities
摘要： Light emitting devices based on Si quantum dots/SiO2 multilayers with dot size of 2.5 nm have been prepared. Bright white light emission is achieved under the dc driving conditions and the turn-on voltage of the device is as low as 5 V. The frequency-dependent electroluminescence intensity was observed under ac conditions of square and sinusoidal wave. It was found that the emission wavelength changes with frequency when sinusoidal ac is applied. The degradation of emission intensity is less than 12% after 3 h for ac driving condition, exhibiting the better device stability compared to the dc driving one.
关键词： electroluminescence (EL),Direct current (dc),Si quantum dots (Si QDs),frequency dependent
更新于2025-09-23 15:21:01
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Volumetric light-shaping polymer-dispersed liquid crystal films for mini-LED backlights
摘要： Volumetric light-shaping polymer-dispersed liquid crystal (PDLC) films for mini-LED backlit liquid crystal displays (LCDs) are proposed and experimentally demonstrated. With proper material engineering and good vertical alignment of liquid crystals, passive PDLC films with angle-selective scattering properties can be achieved. Such films only respond to angles rather than spatial locations. By directly adhering the PDLC films onto a LED, angular intensity distribution of light can be tailored from Lambertian-like to batwing-like. Further simulation shows that by engineering the angular distribution, a fewer number of LEDs or equivalently a shorter light-spreading distance should be required to maintain good uniformity. Such a PDLC film would find widespread applications in emerging mini-LED backlit LCDs and shed light on designing other light-shaping films in the future.
关键词： Polymer-dispersed liquid crystals,volumetric diffusers,angle-dependent scattering,mini-LED backlights
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Sozopol, Bulgaria (2019.9.6-2019.9.8)] 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Evaluation of Unauthorization at the Express-Control of Heating of Natural Gas
摘要： Light emitting devices based on Si quantum dots/SiO2 multilayers with dot size of 2.5 nm have been prepared. Bright white light emission is achieved under the dc driving conditions and the turn-on voltage of the device is as low as 5 V. The frequency-dependent electroluminescence intensity was observed under ac conditions of square and sinusoidal wave. It was found that the emission wavelength changes with frequency when sinusoidal ac is applied. The degradation of emission intensity is less than 12% after 3 h for ac driving condition, exhibiting the better device stability compared to the dc driving one.
关键词： electroluminescence (EL),Direct current (dc),Si quantum dots (Si QDs),frequency dependent
更新于2025-09-23 15:21:01
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[IEEE 2018 11th UK-Europe-China Workshop on Millimeter Waves and Terahertz Technologies (UCMMT) - HangZhou, China (2018.9.5-2018.9.7)] 2018 11th UK-Europe-China Workshop on Millimeter Waves and Terahertz Technologies (UCMMT) - Single-Layer Dual-Band Anisotropic Coding Metasurface With Frequency- and Polarization-Dependent Properties
摘要： In this paper, a single-layer anisotropic coding metasurface is designed to work in dual-band, which has frequency- and polarization-dependent properties. By changing the frequency and polarization of the incident waves, the proposed single coding metasurface can achieve different electromagnetic (EM) functionalities independently. This design is experimentally demonstrated in the microwave frequency band and can be further exploited for realizing multifunctional devices.
关键词： Anisotropic,polarization-dependent,coding metasurface,dual-band
更新于2025-09-23 15:21:01