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State-Resolved Probing of Attosecond Timescale Molecular Dipoles
摘要： We report an experimental study of iodomethane attosecond transient absorption spectroscopy (ATAS) in the region of iodine 4d core-to-valence/Rydberg excitation. Similar to previous atomic experiments, XUV-NIR delay-dependent absorbance changes reflect a light-induced phase due to an NIR-field driven AC Stark shift of the excited states, as well as pathway interferences arising from couplings between neighboring states. As a novel aspect of molecular ATAS, we observe pronounced differences between the ATAS signatures of valence and Rydberg states. While the core-to-valence transitions carry the majority of the XUV oscillator strength, the core-to-Rydberg transitions are dominantly affected by a moderately strong, non-ionizing NIR field. Our experimental findings are corroborated by ab-initio calculations and ATAS simulations.
关键词： core-to-valence,attosecond transient absorption spectroscopy,iodomethane,core-to-Rydberg,AC Stark shift,ab-initio calculations,XUV-NIR
更新于2025-09-04 15:30:14
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OPTIMIZATION OF GREEN SYNTHESIZED SILVER NANOPARTICLES FROM CARALLUMA UMBELLATA
摘要： Objective: The current study focuses on optimization and ecologically innocuous green synthesis of silver nanoparticles (AgNPs) using tribal plant Caralluma umbellata and to study its potential as an antibacterial and antifungal agent. Methods: The synthesis of AgNPs were confirmed by the colour change of the stem extract from yellow to dark brown and by UV-Visible spectroscopy. The optimum conditions for synthesis of AgNPs were analysed using Response surface methodology (RSM) based Box-Behnken design (BBD) using Design Expert software (7.0.0 trial version). The AgNPs synthesized were characterized by Scanning electron microscope (SEM), Energy dispersive X-ray (EDX), Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analysis. Further, antibacterial and antifungal activity were performed using well diffusion method for both plant extract and AgNPs. Results: The UV-Visible spectrum of AgNPs revealed characteristic peak at 425.5 nm. The crystalline nature of synthesized AgNPs was confirmed by XRD with average size 26 nm. SEM confirms the spherical shape of AgNPs and by EDX the presence of elemental silver was observed. The ability of the plant to produce both reducing and capping agents were confirmed by FTIR. The optimum conditions for synthesis of AgNPs were found to be 0.55 mmol AgNO3 concentration, 45 °C temperature and 24h reaction time. Both plant sample and synthesized AgNPs exhibited good antimicrobial activity where AgNPs showed superior efficacy as an antimicrobial agent over the other. Conclusion: From the results obtained, it can be deduced that both C. umbellata stem extract and synthesized AgNPs can act as potent antimicrobial agent. But the synthesized AgNPs is more potent against bacteria and fungus.
关键词： Nanomedicine,BBD,Antimicrobial agent,Tribal plant,Silver nanoparticles
更新于2025-09-04 15:30:14
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Haze Removal of Single Remote Sensing Image by Combining Dark Channel Prior with Superpixel
摘要： Dehazing is important in remote sensing image restorations to enhance the acquired low quality image for interpretation. However, traditional methods have some limitations for dehazing of remote sensing images due to its color distortion and noise. In this paper, we propose an improved method combining superpixel segmentation with luminance information of a haze image to estimate the atmospheric light instead of dark channel prior. Using this method with the haze imaging model, we can directly estimate the thickness of the haze and restore a high quality haze-free image. Experimental results on a variety of remote sensing haze images demonstrate our approach can achieve better image quality when compared with well-known He's [1] method for remote sensing images.
关键词： atmospheric scattering model,Haze removal,superpixel segmentation
更新于2025-09-04 15:30:14
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Valence ππ* Excitations in Benzene Studied by Multiconfiguration Pair-Density Functional Theory
摘要： We explore the valence singlet and triplet ππ* excitations of benzene with complete active space self-consistent field (CASSCF) theory, complete active space perturbation theory (CASPT2), and multiconfiguration pair-density functional theory (MC-PDFT) for four different choices of active space. We propose a new way to quantify the covalent and ionic character of the electronic states in terms of the components of the total electronic energy. We also explore the effect of scaling the exchange and correlation components of the on-top density functional used in MC-PDFT; we observe that increasing the exchange contribution improves the MC-PDFT excitation energies for benzene.
关键词： CASSCF,MC-PDFT,benzene,CASPT2,valence excitations,multiconfiguration pair-density functional theory
更新于2025-09-04 15:30:14
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[IEEE 2018 37th Chinese Control Conference (CCC) - Wuhan (2018.7.25-2018.7.27)] 2018 37th Chinese Control Conference (CCC) - Association Rule Mining for the Infrared Countermeasure by the PF-Growth Algorithm
摘要： To explore the main influence factors in the infrared countermeasure and reveal the effects of the combinations of the influence factors, this study provides a heuristic idea by adopting the association rule mining theory. First of all, an engagement model including the target model, flare model and missile model is constructed to show different attack situations and countermeasure modes. Meanwhile, a counter-countermeasure algorithm denoted overlap effect is proposed as a recognition approach for distinguishing the true target from the target-flare mixed signal. Then, in view of the miss distance, we separate the association rules into outer and inner levels for mining the relations between the miss distance and the countermeasure factors. Afterwards, FP-growth algorithm is introduced to unearth the association rules by using the off-line data. Finally, we thoroughly investigate the association rules and disclose the main influence factors through simulation examples.
关键词： miss distance,FP-growth algorithm,overlap effect,Infrared countermeasure,association rule mining
更新于2025-09-04 15:30:14
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All-Silicon Topological Semimetals with Closed Nodal Line
摘要： Owing to the natural compatibility with current semiconductor industry, silicon allotropes with diverse structural and electronic properties provide promising platforms for the next-generation Si-based devices. After screening 230 all-silicon crystals in the zeolite frameworks by first-principles calculations, we disclose two structurally stable Si allotropes (AHT-Si24 and VFI-Si36) containing open channels as topological node-line semimetals with Dirac nodal points forming a nodal loop in the kz=0 plane of Brillouin zone. Interestingly, their nodal loops protected by inversion and time-reversal symmetries are robust against SU(2) symmetry breaking due to very weak spin-orbit coupling of Si. When the nodal lines are projected onto the (001) surface, flat surface bands can be observed because of the nontrivial topology of the bulk band structures. Our discoveries extend the topological physics to the three-dimensional Si materials, highlighting the possibility to realize low-cost, nontoxic and semiconductor-compatible Si-based electronics with topological quantum states.
关键词： Zeolite frameworks,Node-line semimetals,Topological semimetals,Silicon allotropes,First-principles calculations
更新于2025-09-04 15:30:14
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[IEEE 2018 International Power Electronics Conference (IPEC-Niigata 2018-ECCE Asia) - Niigata (2018.5.20-2018.5.24)] 2018 International Power Electronics Conference (IPEC-Niigata 2018 -ECCE Asia) - The Lifetime Assessment of a Micro-Inverter for PV Applications
摘要： Recently, introducing grid-tied PV systems is recommended in many countries. The inverter lifetime in PV applications is affected by their operating conditions. That is affected by the thermal loading of the power devices lifetime of electrolytic capacitors. Especially, the electrolytic capacitors at the DC-link to compensate the power ripple decreases when the ambient temperature increases. To improve the lifetime, a micro-inverter with an active buffer at the DC-link is introduced in this paper. In this micro-inverter, the DC-link electrolytic capacitor is replaced with a ceramic capacitor that has small capacitance. However, the reliability performance of the entire micro-inverter has not been evaluated. This paper thus assesses the lifetime of the micro-inverter considering the operational conditions (i.e., ambient temperature and solar irradiance, also referred to as mission profiles). A comparison between the proposed circuit with an active buffer and the conventional circuit based on a boost chopper is performed in this paper. It is revealed that the lifetime of the micro-inverter is very long. This is due to the over-designed power devices.
关键词： Photovoltaic,Lifetime estimation,Micro inverter
更新于2025-09-04 15:30:14
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Highly Efficient Fluorescent Organic Light-Emitting Devices Using a Luminescent Radical as the Sensitizer
摘要： In traditional fluorescent organic light-emitting diodes (OLEDs), the upper limit of internal quantum efficiency (IQE) is only 25% because 75 % triplet excitons created on the fluorescent dyes are non-luminous. Here, luminescent radicals are proposed as the sensitizer. Under ideal conditions, electrons and holes firstly recombine on the sensitizer molecule to create doublet excitons, then through energy transfer to generate singlet excitons on the fluorescent dye, finally via radiative decay to emit light. The upper limit of IQE can theoretically reach 100%. As an example, the maximum external quantum efficiency (EQE) of a fluorescent OLED sensitized by a luminescent radical, TTM-1Cz, has reached 8.1%, which is much higher than the upper limit of EQE of traditional fluorensenct OLEDs. Our results suggest a new route to realize highly efficient fluorescent OLEDs.
关键词： organic light-emitting device,doublet,luminescent radical,sensitize,deep-red
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE Radio and Antenna Days of the Indian Ocean (RADIO) - Mauritius (2018.10.15-2018.10.18)] 2018 IEEE Radio and Antenna Days of the Indian Ocean (RADIO) - Self-Interference in LTE-Advanced and 5G NR Transceivers
摘要： The upgrade from 3GPP Long Term Evolution (LTE) towards LTE-Advanced introduced Carrier-Aggregation (CA), necessitating multiple receivers (RX) and transmitters (TX) operating concurrently on a single transceiver die, causing potential interference among them. The introduction of 5G New Radio (5G NR) will require Dual Connectivity (DC) with LTE in the first phase and thus also require a multitude of parallel-operating high-performance receive and transmit chains in a multi-mode LTE-A/5G NR transceiver, driving the need for analog and digital techniques for self-interference mitigation due to coupling between different parts of the transceiver. This paper catalogs the various cross-talk effects and presents digital as well as mixed-signal interference mitigation techniques in condensed form.
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE Radio and Antenna Days of the Indian Ocean (RADIO) - Mauritius (2018.10.15-2018.10.18)] 2018 IEEE Radio and Antenna Days of the Indian Ocean (RADIO) - Five-Stub Directional Device with Substantially Reduced Overall Dimensions
摘要： In this paper, a compact design of a five-stub microstrip coupler with significantly reduced overall dimensions has been investigated. To reduce the size, an artificial transmission line was used, with equivalent characteristics at a central operating frequency of 1000 MHz and in its vicinity, with the characteristics of an even-wave-length segment. Using the program of electrodynamic modeling AWR DE, a standard and compact coupler design was simulated. Due to the fact that the artificial line is shorter and the protruding elements are located, so that to maximally use the free space of the coupler without crossing with neighboring conductive lines from other lines, it was possible to reduce the area of the traditional coupler by 70% in relation to the area of the standard design, while the reduction in the band of operating frequencies occurred by 10%.
关键词： five-stub coupler,microstrip coupler,AWR DE,miniaturization,artificial transmission line
更新于2025-09-04 15:30:14