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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Compressive Sensing Approach to the Synthesis of Sparse Antenna Arrays
摘要： The Compressive Sensing (CS) technique, ?rst introduced in the ?eld of image processing, is nowadays used in many engineering problems. Electromagnetics counts a number of problems which have been solved with a suitable CS-based strategy, such as, for examples, the diagnosis and synthesis of antenna arrays, the estimation of directions of arrival, and the solution of inverse scattering and radar imaging problems. This paper presents an overview of some algorithms based on the CS approach, recently developed by the authors for the synthesis of sparse antenna arrays, also including additional constraints.
关键词： recon?gurable arrays,power pattern synthesis,near-?eld,aperiodic arrays,compressive sensing
更新于2025-09-04 15:30:14
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Structural and optoelectronic properties of Ce-Al2O3 nanoparticles prepared by sol-gel precursors
摘要： Pure and Ce-doped Al2O3 nanoparticles (NPs) were synthesized in different cerium percentages of 1%, 2%, and 3% by cerium chloride and aluminum nitrate precursors in the presence of powerful reducing agent-NaBH4 and CTAB stabilizers using sol-gel method. To examine the crystal, morphological, optical, and electronic properties, the XRD, FESEM, TEM, FTIR, UV-DRS, and PL analyses were used for the heated samples in 1000 °C for 4 hours. The XRD analysis indicated that the pure sample has γ, δ and θ phases, and the structure remained unchanged when Ce impurity was increased. The EDS analysis showed that the percentage of Al element was 47.40 wt% in the pure sample and that it increased to 53.83 wt% for 1% doped sample increasing Al ions in tetrahedral and octahedral sites of alumina through increasing Ce impurities. The TEM results revealed the sphere-like particles with mean particle size of 26 nm in diameter at a 3% level of impurity. The FTIR result showed that an increase in AlO4 adsorption peak in 821 cm-1 compared to AlO6 adsorption peak in 619 cm-1 was due to the dominance of vibrating bonds of tetrahedral sites rather than octahedral sites in alumina. The optical UV-DRS analysis also demonstrated the redshift configuration in a sample by increasing Ce dopant and reducing energy bandgap from 4.10 to 3.26 eV for pure and 3% Ce-doped Al2O3 NPs, respectively. Finally, the photoluminescence (PL) results indicated that increasing Ce dopant reduced electron-hole recombination leading to an increase in photocatalytic activity.
关键词： Chemical Synthesis,Cerium dopant,Sol-gel,Ceramics,Al2O3 NPs
更新于2025-09-04 15:30:14
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Crystal Structure and Luminescent Property of a One-Dimensional Chain Based on 1-(4-Nitrophenyl)-1,2,4-Triazole
摘要： A neutral one-dimensional CdII coordination polymer [Cd(NO2–BDC)(NPT)(H2O)2]n (1) (NO2–H2BDC=5-nitro-1,3-benzenedicarboxylic acid, NPT=1-(4-nitrophenyl)-1,2,4-triazole) is prepared and characterized through IR, elemental and thermal analyses, and single crystal X-ray diffraction. The single crystal X-ray diffraction analysis reveals that complex 1 is comprised of neutral 1D zigzag chains. The luminescence and thermal stability of complex 1 are investigated.
关键词： 1-(4-nitrophenyl)-1,2,4-triazole,one-dimensional chain,luminescence,coordination polymer,synthesis,5-nitro-1,3-benzenedicarboxylic acid
更新于2025-09-04 15:30:14
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Solvothermal Synthesis and Characterization of Flower-Like b-In2S3 Microparticles
摘要： Flower-like β-In2S3 particles have been successfully synthesized via solvothermal process by using acetylacetone-water solvent mixture. The products were characterized by X-ray diffraction, scanning electron microscopy, reflectance spectra. X-ray diffraction analysis confirms the formation of cubic β-In2S3. Microstructural investigation with SEM indicated that the particle size increases with increasing reaction time. The optical band gap determined from reflectance spectra was found to have values within the range of 2.34-2.49 eV.
关键词： Microstructure,Solvothermal synthesis,Optical properties,β-Indium sulphide,Acetylacetone-water solvent system
更新于2025-09-04 15:30:14
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A Facile Green Approach for Synthesis of Selenium Nanowires with Visible Light Photocatalytic Properties
摘要： In this work, high purity trigonal selenium (t-Se) nanowires were synthesized through a simple one-step solvothermal process at 50 °C. Sodium formaldehyde sulfoxylate (SFS) was used as a reducing agent. To our knowledge, this is the first time that SFS was used as the reducing agent for synthesis of Se nanostructures. In this method, Se nanowires were obtained at lower temperature, shorter period of reaction time and without using complex equipment. The experimental parameters, such as reaction duration, temperature and amount of surfactant, were investigated. The as-prepared Se nanowires have a diameter of about 100–200 nm and length of up to 10 μm. A “Solid–Solution–Solid” growth mechanism was proposed. In the presence of H2O2, the Se nanowires showed good catalytic performance, where over 99% of methylene blue (MB) was degraded in 3.0 h. Results from this study demonstrated that the Se nanowires exhibit a promising application for photodegradation.
关键词： Synthesis,Photocatalytic Performance,Selenium,Nanowires
更新于2025-09-04 15:30:14
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Dithienobenzimidazole‐containing conjugated donor–acceptor polymers: Synthesis and characterization
摘要： The synthesis of two new conjugated polymers based on the relatively under-exploited monomer, 5,8-dibromo-2-[5-(2-hexyldecyl)-2-thienyl]-1H-dithieno[3,2-e:20,30-g]benzimidazole (dithienobenzimidazole, DTBI), and either 4,7-bis[4-hexyl-5-(trimethylstannyl)-2-thienyl]-2,1,3-benzothiadiazole (BTD) or 2,6-bis(trimethylstannyl)-4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b0]dithiophene (BDT) is described. The polymers were synthesized via Stille polycondensation and characterized by traditional methods (1H NMR, gel-permeation chromatography, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, thermal gravimetric analysis, differential scanning calorimetry, ultraviolet–visible spectroscopy, photoluminescence, and cyclic voltammetry). Prior to their synthesis, trimer structures were modeled by DFT calculations facilitating a further understanding of the systems’ electronic and geometric structure. Polymers were titrated with acid and base to take advantage of their amphiprotic imidazole moiety and their optical response monitored with ultraviolet–visible spectroscopy. Finally, pristine polymer thin-films were treated with acid and base to evaluate (de)protonation’s effect on system electronics, but thin-film degradation was encountered.
关键词： addition polymerization,synthesis,conjugated,conducting polymers,semiconducting polymer,dithienobenzimidazole,ionomers,donor–acceptor
更新于2025-09-04 15:30:14
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[IEEE 2018 15th European Radar Conference (EuRAD) - Madrid, Spain (2018.9.26-2018.9.28)] 2018 15th European Radar Conference (EuRAD) - A Plane-Wave Synthesis Approach for 3D Monostatic RCS Prediction from Near-Field Measurements
摘要： A plane-wave synthesis approach for determining the 3D monostatic radar cross section from a set of near-field measurements is presented. Compared to image based techniques, it does not suffer from inaccuracies in the case of multiple interactions. At the same time, very general measurement setups are possible without introducing severe truncation errors and the resulting field transformation problem can still be solved efficiently, due to the implementation based on propagating plane-wave expansions of the Green’s function. The theory of the algorithm is first outlined and then validated using simulated near-field and far-field data.
关键词： plane-wave synthesis,radar cross section measurement,near-field far-field transformation
更新于2025-09-04 15:30:14
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Recent development of A2B2O7 system transparent ceramics
摘要： A2B2O7 system compounds, which usually present three phase structures mainly based on the ionic radius ratios of rA and rB (rA/rB), have been studied for potential applications in many fields, such as thermal barrier coatings, luminescence powders, fast-ion conductors, photocatalysts, and matrices for immobilization of highly active radionuclides. Since 2005, La2Hf2O7 was fabricated into transparent ceramics and much more attentions were paid on A2B2O7 transparent ceramics for new applications. In this review, the development of A2B2O7 system transparent ceramics was described. The structure characteristics, powder synthesis method, and sintering techniques of the final A2B2O7 transparent ceramics were summarized. After that, the mostly reported A2Hf2O7, A2Zr2O7, and A2Ti2O7 system transparent ceramics were systematically introduced. The potential application fields and future development trends were also discussed, focusing on scintillators, optical elements, and other luminescent materials.
关键词： A2B2O7 system transparent ceramics,potential applications,sintering,powder synthesis
更新于2025-09-04 15:30:14
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Carbon nanotube based metal-organic framework nanocomposites: Synthesis and their photocatalytic activity for decolorization of colored wastewater
摘要： Herein, Materials Institute Lavoisier (MIL-125(Ti))/carbon nanotube (CNT) nanoporous composites (MIL/CNT) were synthesized by hydrothermal method. Different amounts of CNT (0.01 g and 0.03 g) were used to synthesize nanocomposites (denoted as MIL/CNT(0.01) and MIL/CNT(0.03), respectively). The synthesized nanomaterials (MIL, MIL/CNT(0.01) and MIL/CNT(0.03)) were characterized by XRD, FTIR, TGA, BET, SEM, and zeta potential and used for photocatalytic dye degradation. Reactive Black 5 (RB5) was used as a model pollutant. The zeta potential of MIL and MIL/CNT (0.01) were ?27.7 mV and 19.2 mV, respectively. The data showed that that MIL/CNT(0.01) nanocomposite had higher photocatalytic dye degradation due to the synergistic effect of CNT. Dye decolorization by the nanomaterials followed the zero-order kinetics reaction. The decolorization rate was 0.0015, 0.0019, 0.0024 mg/L min for MIL, MIL/CNT(0.01) and MIL/CNT(0.03), with the correlation coefficient of 0.9639, 0.9906, and 0.9757, respectively. The synthesized catalysts were reusable over two cycles.
关键词： Metal-organic framework-carbon nanotube nanocomposite,Photocatalytic dye degradation,Reactive Black 5,Synthesis
更新于2025-09-04 15:30:14
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Hydrothermal synthesis of flower-like Na-doped α-Bi2O3 and improved photocatalytic activity via the induced oxygen vacancies
摘要： Na-doped α-Bi2O3 with a hierarchical flower-like shape was successfully prepared via a facile hydrothermal reaction. The samples consisted of well-crystalized nanoplates with smooth surfaces and a thickness of tens of nanometers. The phase formation was investigated via X-ray powder diffraction (XRD) patterns and structural refinements. The formations of oxygen vacancies were verified and its effects on the optical and photocatalysis were discussed. The band gap of α-Bi2O3 was narrowed via forming the local energy levels by oxygen vacancy defect complexes in the lattices. The photocatalytic activities on photo-degradation of Rhodamine B (RhB) were significantly improved. The effective photocatalysis was discussed on the improved visible-light response, band structure, and dynamic luminescence decay. The photocatalysis of Na-doped α-Bi2O3 was improved via the induced oxygen vacancies. The reported hydrothermal synthesis was advantageous approach to prepare α-Bi2O3 by considering the simplicity, low reaction temperature, no post-sintering, without using any template or surfactant, large-scale production, low cost, etc.
关键词： Photocatalysis,Semiconductor,Hydrothermal synthesis,Optical properties,Oxygen vacancies
更新于2025-09-04 15:30:14