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Dual-Band Binary Metamaterial Absorber Based on Low-Permittivity All-Dielectric Resonance Surface
摘要： A binary-structured metamaterial absorber (BMA) consisting of a low-permittivity dual-layer all-dielectric resonance surface (ADRS) and re?ector was simulated and experimentally validated. Analyses of relative impedance, electric/magnetic ?eld and power loss density indicated that the proposed BMA exhibits two absorption peaks at 14.65 GHz and 16.61 GHz, resulting from the magnetic and electrical responses of ADRS, respectively. The dependences of absorption properties on the dimensions of the ADRS and material parameters of the ADRS are discussed. It is concluded that the upper layer of the ADRS acts as an impedance-matching layer directly in?uencing the absorption intensity, while the bottom layer offers frequency selectivity in the 13–15 GHz range. The current design uses a low-permittivity ADRS, with simpli?ed design and easy preparation and is notably different from conventional ternary-structured metamaterial absorbers based on a metallic resonance surface. The simplicity of the proposed BMA makes it a promising low-cost ambient temperature alternative to conventional metamaterial absorbers and could open up practical applications.
关键词： Binary-structured metamaterial absorber,simpli?ed design and easy preparation,frequency selectivity,low-permittivity all-dielectric resonance surface
更新于2025-09-10 09:29:36
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Reference Module in Chemistry, Molecular Sciences and Chemical Engineering || Polymer Electrodes: Preparation, Properties, and Applications☆
摘要： Good electric conductivity acquired through redox processes is the flagship property of polymers containing extended conjugated p-electron systems. It was discovered by Heeger and MacDiarmid in polyacetylene synthesized by Shirakawa’s method. Polyacetylene is chemically the simplest example amongst a vast collection of such materials, but it is environmentally unstable. Instead, polyheteroaromatics, such as polypyrrole and polythiophene, and polyaniline (polyphenylamine), as well as their derivatives, are of foremost interest because of applications in analytical sensors, power sources, separation devices, optoelectronic devices, and controllable platforms of chemical and biochemical reactions.
关键词： Preparation,Applications,Polythiophene,Polypyrrole,Properties,Polymer Electrodes,Conducting Polymers,Polyaniline
更新于2025-09-10 09:29:36
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Efficiency calibration of a coaxial HPGe detector-Marinelli beaker geometry using an 152Eu source prepared in epoxy matrix and its validation by efficiency transfer method
摘要： In this study, an in-house 152Eu calibration source was produced from a custom epoxy matrix with a density of r ? 1.14 g cm(cid:2)3, which is chemically stable and durable form after its solidification. The homogeneity of 152Eu in matrix was obtained better than 98%. For a Marinelli beaker geometry, an efficiency calibration procedure was applied to a n-type, coaxial, 78.5% relative efficient HPGe detector in the energy range of 121.7e1408.0 keV by using in-house 152Eu calibration source. Then the measured efficiencies for Marinelli geometry were compared with the results calculated by MEFFTRAN and ANGLE softwares for the validation. Although MEFFTRAN and ANGLE have two different efficiency transfer algorithms to calculate the efficiencies, they usually need to use a reliable and accurate reference efficiency values as input data. Hence, reference efficiency values were obtained experimentally from a multinuclide standard source for the same detector- Marinelli geometry. In the present source characterization, the corrections required for self-absorption and true coincidence summing effects for 152Eu gamma-rays were also obtained for a such close counting geometry condition. The experimental results confirmed the validity of efficiency calculations obtained by MEFFTRAN and ANGLE softwares that are calculation tools.
关键词： In-house source preparation,Epoxy,Efficiency transfer,MEFFTRAN,Marinelli geometry,152Eu,ANGLE,Gamma-ray spectrometry
更新于2025-09-10 09:29:36
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Remote state preparation using Einstein–Podolsky–Rosen representations
摘要： Because Einstein–Podolsky–Rosen states are well-de?ned on the Weyl algebra, their canonical cyclic representations are suitable for demonstrating the process of remote state preparation. Local projection-valued measurements and the corresponding recovery unitary operator are formulated in this representation, whereupon generalized equatorial states are prepared remotely and faithfully.
关键词： Einstein–Podolsky–Rosen states,canonical cyclic representations,remote state preparation,Weyl algebra
更新于2025-09-10 09:29:36
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GeSn surface preparation by wet cleaning and in-situ plasma treatments prior to metallization
摘要： GeSn, a group IV binary alloy, is currently of high interest. Its use is envisioned in two kinds of applications: (i) as a source/drain compressive stressor in order to boost the hole mobility in short gate length Ge channel p-type MOSFETs [1] and (ii) as a direct-band-gap material for Si photonics, provided that the Sn content is higher than 10%, typically [2]. However, the fabrication of GeSn-based components faces major technological issues. First of all, as the lattice mismatch between Sn and Ge is large (14%) and the solubility of Sn in Ge low at thermodynamic equilibrium (< 1%), specific conditions have to be used for the epitaxial growth of high Sn content GeSn layers. Moreover, the fabrication of efficient ohmic contacts to receive and deliver power and signals is challenging. Ni-stanogermanides are currently under investigation in order to benefit from low contact resistivity (Rc) and sheet resistance (Rsh) in GeSn-based devices. The surface preparation of such metastable alloys will then be an unavoidable step. Whatever the targeted application, wet cleaning is indeed mandatory to remove particles, organic materials, metallic impurities and native oxides from the surface. Literature data on GeSn surface preparation prior to metallization is currently scarce [3], [4]. Based on the existing knowledge on pure germanium, we will likely have to cope with a high dissolution in oxidant solutions (GeO2 dissolution in water) and unstable surface preparations (high reactivity upon air and oxygen exposure). Ex-situ wet cleanings will likely suffer from a fast native oxide regrowth on the GeSn surface. In-situ plasma treatments in a chamber connected to the metal deposition chamber itself, i.e. without any air break, should enable to get rid of that problem. In this work, after a characterization of the native oxide formed upon air exposure of Ge0.85Sn0.15 alloys, we investigate the impact of i) wet chemistries, ii) plasma treatments and iii) “wet + plasma” combinations on GeSn surface oxide removal.
关键词： surface preparation,GeSn,metallization,wet cleaning,plasma treatments
更新于2025-09-09 09:28:46
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Physical Properties of Solid Solutions InxAl1–xN
摘要： The phase diagrams and the results of studies of the GaN, AlN and InN ternary solid solutions grown using the magnetron sputtering, molecular beam epitaxy, and metalorganic vapour-phase epitaxy technologies and intended for the production of ultrahigh-frequency InAlN/GaN HEMT transistors are analyzed.
关键词： preparation methods,phase diagrams,InxAl1–xN solid solutions,properties
更新于2025-09-09 09:28:46
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Recognizing and Preventing Artifacts in Microscopy: A Roundtable Discussion
摘要： In 1991 the Technologists’ Forum presented a symposium on artifacts in biological electron microscopy [1]. Since that time the topic has not been re-visited in our symposia, special topics or roundtable discussions. Artifacts are damage caused in specimen preparation and can be confused with specimen ultrastructure. Many artifacts are a result of mechanical or chemical action during sample preparation and some artifacts are due to irradiation by the electron beam during examination of the specimen in the microscope. Recognizing specimen damage is the initial step in preventing the same problem in future preparations and not reporting erroneous data.
关键词： electron microscopy,TEM,specimen preparation,microscopy,artifacts,SEM
更新于2025-09-09 09:28:46
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Nanostructured Titania Templated by Natural Cellulose Substance: Effect of Vanadium-Doping on the Anatase-to-Rutile Phase Transformation
摘要： Vanadium-doped rutile titania nanomaterial was synthesized by calcination of titania/vanadia composite thin gel films pre-coated natural cellulose substance (e.g., ordinary filter paper) at a relatively low temperature (600 °C). A better mixture of titanium and vanadium species is achieved during the layer-by-layer (LbL) deposition process with cellulose nanofiber as a template, leading to more vanadium dopants incorporated in the titania crystal lattices. By sufficient vanadium-doping, the phase transformation temperature from anatase to rutile phase of titania is decreased effectively. The doping mode and existing state of vanadium in the titania nanomaterials and the effect on the anatase-to-rutile phase transformation have been studied. This strategy provides a facile and effective route to facilitate the phase transformation of various nanostructured metal oxides templated by natural cellulose substance through doping appropriate functional metal ions in the LbL deposition process.
关键词： Biomimetic,Ceramics,Sol–Gel Preparation,Phase Transformation,Titania
更新于2025-09-04 15:30:14
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A new methodology for the determination of silicon in plants by wavelength dispersive X-ray fluorescence
摘要： Silicon is an important element for plants at their structure and physiology and plays an important role in bone mineralization and soft tissue development in human beings. Furthermore, its determination is being requested more frequently due to nutritional requirements. However, the methods found in the literature to determine silicon in this type of samples require a sample preparation step, which makes them time‐consuming and provides high uncertainties. In this paper, a method for the determination of silicon in plants by wavelength dispersive X‐ray fluorescence (WD‐XRF) spectrometry has been developed. Horsetail (Equisetum arvense L.) and nettle leaf (Urtica dioica) have been used as a source of silicon due to its medical use. Sample preparation involved calcining the sample at 700°C and preparing fused beads from the calcined sample. Calibration standards for WD‐XRF measurement were prepared by mixing certified reference materials and chemical products to reproduce the samples matrix. The linear range for silicon concentration ranges from 6 to 55 wt% SiO2. The validation of the method was performed measuring a reference material (NCS DC73349 Bush branches and leaves) and comparing the results obtained by WD‐XRF with those obtained by an independent method by atomic absorption spectrometry. The developed methodology is rapid and accurate, provides low uncertainties, and is environmentally friendly, as it does require the use of less hazardous reagents.
关键词： silicon,WD‐XRF,wavelength dispersive X‐ray fluorescence,sample preparation,plants,fused beads
更新于2025-09-04 15:30:14
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Investigation of a Rapid Infrared Heating Assisted Mineralization of Soybean Matrices for Trace Element Analysis
摘要： A fast sample preparation procedure based on use of infrared (IR) assisted heating for mineralization of soybean derived samples has been developed for their subsequent multielement analysis by inductively coupled plasma optical emission spectrometry (ICP-OES) and flame atomic absorption spectrometry (FAAS). A cold finger was examined for refluxing of acid vapors to determine its impact on efficiency and economy of digestion. The optimized procedure, based on 1 g subsamples, 8 ml of HNO3 (65% w/w) and exposure of the mixture to a 500 W IR source for 5 min without refluxing, permitted accurate determination of all analytes in NIST SRM 1568b (rice flour). Detection limits using ICP-OES were (μg/kg) 97, 1.0, 39, 185, 0.47 and 1200 for Ca, Cu, Fe, K, Mn and P, respectively, and 18 for Zn by FAAS. The IR-assisted digestion approach provided a low cost, easy to use system having great potential for implementation in routine analysis of trace elements in soybean and similar matrices.
关键词： ICP-OES,soybean,infrared radiation,sample preparation,trace element analysis
更新于2025-09-04 15:30:14