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- 2018
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- periodic paperclip-shaped structure
- antenna array
- mutual coupling reduction
- Bessel Function
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- Fusion temperature and Elongation speed
- Electronic Science and Technology
- Physics
- UIN Suska Riau
- Xi'an University of the Science and Technology
- University of Riau
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Conjugated HCl-doped polyaniline for photocatalytic oxidative coupling of amines under visible light
摘要： HCl-Doped polyaniline (PANI-ES) and PANIs of different oxidation states were prepared by a typical oxidative polymerization and subsequent redox reaction, respectively. The photocatalytic performance of PANIs towards selective benzylamine oxidation reactions under visible light was investigated. PANI-ES containing a polaron structure exhibited the highest light-induced activity (54.9%). The results show that the formation of the surface complex between PANI-ES and adsorbed amine should be responsible for the enhanced visible light activity. The newly formed polaron band in PANI-ES has a greater number of delocalized electrons, which can facilitate electron transfer and thus improve the photoactivity. These results indicate that conjugated conducting polymers can be efficient visible light-responsive nonmetal photocatalysts for green synthesis.
关键词： Conjugated polyaniline,Amines,Visible light,Oxidative coupling,Photocatalysis
更新于2025-09-19 17:15:36
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[IEEE 2018 IEEE 13th Annual International Conference on Nano/Micro Engineered and Molecular Systems (NEMS) - Singapore, Singapore (2018.4.22-2018.4.26)] 2018 IEEE 13th Annual International Conference on Nano/Micro Engineered and Molecular Systems (NEMS) - Novel Mechanical Coupling Piezoelectric Micromachined Ultrasonic Transducers Based on Base Excitation System
摘要： This paper presented a novel piezoelectric micromachined ultrasonic transducer (PMUT) based on mechanical coupling between an annular diaphragm and a circular diaphragm stacking together. The circular diaphragm whose pedestal grounded on the middle of the annular diaphragm, which formed a base excitation system. Compared to the non-coupled traditional circular diaphragm PMUTs, the proposed PMUTs achieved higher transmission sensitivity by 173% with the resonant frequency of 6.14 MHz in water, due to the base excitation amplification of the circular diaphragm. Also, the array transmission performance of the proposed PMUT and non-coupled traditional PMUT with circular diaphragm was compared in the same array dimension. The results indicated that the array composed by the proposed PMUT had less cross-talk effect, which kept the central working frequency almost the same when it work solely.
关键词： mechanical coupling,PMUT,high transmission sensitivity,low cross-talk effect
更新于2025-09-19 17:15:36
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Design of Balanced Filter with Wide Stopband by Using Discriminating Coupling
摘要： This paper presents a novel balanced filter with enhanced stopband by using discriminating coupling. The proposed design utilizes third-order quarter-wavelength coupled resonators to obtain the filtering responses. Discriminating coupling is applied between feedline and resonator. The circuit is theoretically analyzed and implemented for demonstration. The operating frequency is located at 2.4 GHz and the common-mode rejection is larger than 20 dB up to 9 GHz (3.75f0). Due to discriminating coupling, the differential mode out-of-band rejection is larger than 20 dB up to 18 GHz (7.5f0), which shows wide stopband.
关键词： high rejection,wide stopband,discriminating coupling,Balanced filter
更新于2025-09-19 17:15:36
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Hydrothermal Synthesis and Luminescent Properties of Spindle-Like NaGd(MoO <sub/>4</sub> ) <sub/>2</sub> :Eu <sup>3+</sup> Phosphors
摘要： Spindle-like NaGd(MoO4)2: Eu3 + phosphors with various Eu3 + concentrations were prepared via a hydrothermal process and characterized using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The XRD results suggested that the prepared samples had a scheelite structure. The FE-SEM images indicated that the prepared NaGd(MoO4)2: Eu3 + phosphors were spindle-like. The influences of the ratio of sodium citrate and the rare earth cations on the product were studied. It was found that sodium citrate, as the chelating agent, could significantly influence the structure and morphology of the samples. The emission spectra, excitation spectra, fluorescence decay curves, and quantum yields of the samples were measured. The luminescent properties of the materials were studied. The results indicated that the electron–phonon coupling between the Eu3 + and the NaGd(MoO4)2 host was weak, and with the increase of the Eu3 + concentration, the Huang–Rhys factor increased. Additionally, the quantum efficiency of the Eu3 + 5D0 level was calculated, and it was found that the quantum efficiency decreased with the increase of the Eu3 + concentration.
关键词： Electron-phonon coupling,Rare earth,Hydrothermal,Molybdate,Luminescence
更新于2025-09-19 17:15:36
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A four-state fluorescent molecular switch
摘要： Cross-coupling reactions are among the most powerful C–C and C–X bond forming tools in organic chemistry. Traditionally, cross-coupling methods rely on the use of aryl halides or pseudohalides as electrophiles. In the past three years, decarbonylative cross-couplings of amides have emerged as an attractive method for the construction of a wide variety of carbon–carbon and carbon–heteroatom bonds, allowing for the synthetically-valuable functional group inter-conversion of the amide bond. These previously elusive reactions hinge upon selective activation of the N–C(O) acyl amide bond, followed by CO extrusion, in a formal double N–C/C–C bond activation, to generate a versatile aryl–metal intermediate as an attractive alternative to traditional cross-couplings of aryl halides and pseudohalides. In this perspective review, we present recent advances and key developments in the field of decarbonylative cross-coupling reactions of amides as well as discuss future challenges and potential applications for this exciting field.
关键词： amides,transition-metal catalysis,C–C bond formation,decarbonylative cross-coupling,C–X bond formation
更新于2025-09-19 17:15:36
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Effects of the interplay between electron–electron interaction and intrinsic spin–orbit interaction on the indirect RKKY coupling in graphene nanoflakes
摘要： The effects of electron–electron (e–e) interaction and intrinsic spin–orbit interaction (ISOI) on the maximum of the magnetization and the indirect RKKY (Ruderman–Kittel–Kasuya–Yosida) coupling between the magnetic impurities embedded in zig-zag graphene nanoflakes are investigated using the tight-binding Hamiltonian and the mean-field Hubbard model. The RKKY coupling energy values as a function of the e–e interaction strengths are plotted for different values of ISOI strength. The appearance of the e–e interaction and ISOI changes drastically the magnitude of the indirect coupling so that increasing or decreasing of the indirect coupling depends on strength of the e–e interaction and ISOI and the size of the nanoflake. The dependence of the RKKY coupling and the maximum of the magnetization on the positions of the magnetic impurities and the size of the system are studied. We find that the e–e interaction and the ISOI are responsible for changes of the magnetization along the zig-zag edges of the nanoflake.
关键词： spin-orbit interaction,electron-electron interaction,magnetization,graphene nanoflakes,RKKY coupling
更新于2025-09-19 17:15:36
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Highly sensitive and temperature-compensated fiber bending sensing based on directional resonance coupling in photonic crystal fibers
摘要： A highly sensitive bending sensor with temperature-compensation based on magnetic fluids (MF) infiltrated photonic crystal fiber (PCF) is presented. Specific cladding air-holes are filled with MF material to form defective channels and introduce new degrees of freedom for fiber sensing. The structure designed in such way can achieve simultaneous measurement of bend-curvature and bend-direction with temperature compensation. The bending sensitivity can reach to ?6.544 nm/m?1 with a high linearity within the range of curvature from ?10 m?1 to 10 m?1. The proposed two-dimensional (2D) bending vector sensor cannot only improve the sensing precision and measurement range, but also reduce the metrical difficulty and simplify the process.
关键词： Photonic crystal fiber,Directional resonance coupling,Bending sensor
更新于2025-09-19 17:15:36
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Decarboxylative Heck Coupling via a Cobalt/Photoredox Catalysis
摘要： The authors report a synthesis of olefins through a photoinduced decarboxylative Heck-type coupling. The method uses alkyl carboxylic acids, which are one of the most ubiquitous building blocks. Based on DFT calculations, a radical mechanism has been proposed. Over 90 examples containing a huge variety of functional groups have been prepared in high yields.
关键词： Heck coupling,cobalt catalysis,photoredox catalysis
更新于2025-09-19 17:15:36
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<i>Ab initio</i> quantum-chemical computations of the absorption cross sections of HgX <sub/>2</sub> and HgXY (X, Y = Cl, Br, and I): molecules of interest in the Earth's atmosphere
摘要： The electronic-structure properties of the low-lying electronic states and the absorption cross sections (σ(E)) of mercury halides HgCl2, HgBr2, HgI2, HgBrCl, HgClI, and HgBrI have been determined within the UV-vis spectrum range (170 nm ≤ λphoton ≤ 600 nm) by means of the DKH3-MS-CASPT2/SO-RASSI quantum-chemical methodology (with the ANO-RCC basis set) and a semi-classical computational strategy based on nuclear sampling for simulating the band shapes. Computed band energies show a good agreement with the available experimental data for HgX2 with errors around 0.1–0.2 eV; theoretical and σ(E) are within the same order of magnitude. For the mixed HgXY compounds, the present computed data allow us to interpret previously proposed absorption bands estimated from the spectra of the parent molecules HgX2 and HgY2, measured in methanol solution. The analyses performed on the excited-state electronic structure and its changes around the Franck–Condon region provide a rationale on the singlet–triplet mixing of the absorption bands and the heavy-atom effect of the Hg compounds. Furthermore, the present benchmark of HgX2 and HgXY absorption σ values together with the previous benchmark of the electronic-structure properties of HgBr2 [see S. P. Sitkiewicz, et al., J. Chem. Phys., 2016, 145, 244304] has been helpful to set up a methodological and computational protocol which shall be used for predicting the atmospheric absorption and photolysis properties of several Hg compounds present in the atmospheric cycle of Hg.
关键词： semi-classical approach,quantum-chemical computations,Earth's atmosphere,UV-vis spectrum,spin-orbit coupling,mercury halides,absorption cross sections
更新于2025-09-19 17:15:36
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Heterogeneous Cationa??Lattice Interaction and Dynamics in Triple-Cation Perovskites Revealed by Infrared Vibrational Nanoscopy
摘要： Hybrid organic-inorganic perovskites exhibit extraordinary photovoltaic performance. This is believed to arise from almost liquid-like low-energy interactions among lattice ions and charge carriers. While spatial variations have recently been identified over multiple length scales in the optoelectronic responses, the relationship of the heterogeneity and the soft cation-lattice interactions has remained elusive. Here, we apply multivariate infrared vibrational nano-imaging to a formamidinium (FA)-methylammonium (MA)-cesium triple cation perovskite. By using the FA vibrational resonance as a probe of its local chemical environment, through spatial variation and correlation in composition, strength of cation-lattice coupling and its associated few-ps vibrational dynamics, we reveal how a varying local reaction field is correlated with the cation-lattice coupling. We attribute the associated heterogeneous lattice contraction to a non-uniform distribution of cesium cations. The observed varying elasticity of the lattice leads to disordered charge-phonon coupling and polaron formation, the control of which is central to improving perovskite photovoltaics.
关键词： charge-phonon coupling,infrared vibrational nano-imaging,Hybrid organic-inorganic perovskites,lattice contraction,photovoltaic performance,cation-lattice coupling,polaron formation,vibrational dynamics
更新于2025-09-19 17:13:59