35,446 results match your criteria dielectric

Quasiparticle Electronic Structure of Two-Dimensional Heterotriangulene-Based Covalent Organic Frameworks Adsorbed on Au(111).

J Phys Condens Matter 2021 Apr 13. Epub 2021 Apr 13.

Chemistry, Wayne State University, 5101 Cass Ave, Detroit, Michigan, 48202, UNITED STATES.

The modular nature and unique electronic properties of two-dimensional (2D) covalent organic frameworks (COFs) make them an attractive option for applications in catalysis, optoelectronics, and spintronics. The fabrications of such devices often involve interfaces formed between COFs and substrates. In this work, we employ the first-principles GW approach to accurately determine the quasiparticle electronic structure of three 2D carbonyl bridged heterotriangulene-based COFs featuring kagome lattice, with their properties ranging from a semi-metal to a wide-gap semiconductor. Read More

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An affinity prediction approach for the ligand of E3 ligase Cbl-b and an insight into substrate binding pattern.

Bioorg Med Chem 2021 Apr 2;38:116130. Epub 2021 Apr 2.

State Key Laboratory of Natural Medicines, and Jiang Su Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing 210009, China; Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, China. Electronic address:

Protein-protein interactions (PPIs) are essentially fundamental to all cellular processes, so that developing small molecule inhibitors of PPIs have great significance despite representing a huge challenge. Studying PPIs with the help of peptide motifs could obtain the structural information and reference significance to reduce the difficulty in the development of small molecules. Computational methods are powerful tools to characterize peptide-protein interactions, especially molecular dynamics simulation and binding free energy calculation. Read More

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Mobile Protons Limit the Stability of Salt Bridges in the Gas Phase: Implications for the Structures of Electrosprayed Protein Ions.

J Phys Chem B 2021 Apr 13. Epub 2021 Apr 13.

Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada.

Electrosprayed protein ions can retain native-like conformations. The intramolecular contacts that stabilize these compact gas-phase structures remain poorly understood. Recent work has uncovered abundant salt bridges in electrosprayed proteins. Read More

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Breast lesion detection through MammoWave device: Empirical detection capability assessment of microwave images' parameters.

PLoS One 2021 13;16(4):e0250005. Epub 2021 Apr 13.

UBT-Umbria Bioengineering Technologies, Perugia, Italy.

MammoWave is a microwave imaging device for breast lesions detection, which operates using two (azimuthally rotating) antennas without any matching liquid. Images, subsequently obtained by resorting to Huygens Principle, are intensity maps, representing the homogeneity of tissues' dielectric properties. In this paper, we propose to generate, for each breast, a set of conductivity weighted microwave images by using different values of conductivity in the Huygens Principle imaging algorithm. Read More

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Surface Normals and Light Directions from Shading and Polarization.

IEEE Trans Pattern Anal Mach Intell 2021 Apr 13;PP. Epub 2021 Apr 13.

We introduce a method of recovering the shape of a smooth dielectric object using diffuse polarization images taken with different directional light sources. We present two constraints on shading and polarization and use both in a single optimization scheme. This integration is motivated by photometric stereo and polarization-based methods having complementary abilities. Read More

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Trioctylphosphine-Assisted Pre-protection Low-Temperature Solvothermal Synthesis of Highly Stable CsPbBr/TiO Nanocomposites.

J Phys Chem Lett 2021 Apr 13:3786-3794. Epub 2021 Apr 13.

Centre for Micro and Nano Devices, Department of Physics, COMSATS Institute of Information Technology, Islamabad 44500, Pakistan.

Lead halide perovskite quantum dots (PQDs) are reported as a promising branch of perovskites, which have recently emerged as a field in luminescent materials research. However, before the practical applications of PQDs can be realized, the problem of poor stability has not yet been solved. Herein, we propose a trioctylphosphine (TOP)-assisted pre-protection low-temperature solvothermal synthesis of highly stable CsPbBr/TiO nanocomposites. Read More

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High mobility field-effect transistors based on MoS2 crystal grown by the flux method.

Nanotechnology 2021 Apr 12. Epub 2021 Apr 12.

School of Electronic and Electrical Engineering, Sungkyunkwan University, 300 Chun chun dong, Jangan - gu, Suwon-city 440-746, KOREA, Suwon, Korea (the Republic of).

Two-dimensional (2D) molybdenum disulphide (MoS2) transition metal chalcogenides (TMDs) have great potential in optical and electronic device applications; however, the performance of MoS2 is limited by its crystal quality, which serves as a measure of defects and grain boundaries in the grown material. Therefore, high-quality growth of MoS2 crystals continues to be a critical issue. In this context, we propose the formation of high-quality MoS2 crystals via flux method. Read More

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Structure, ferroelasticity and Goldilocks zone phase transitions in CHNAl(SO)·6HO.

Acta Crystallogr B Struct Sci Cryst Eng Mater 2021 Apr 12;77(Pt 2):225-231. Epub 2021 Mar 12.

Faculty of Chemistry, University of Wroclaw, F. Joliet-Curie 14, 50-383 Wroclaw, Poland.

The single crystal growth and sequence of reversible phase transition are described for CHNAl(SO)·6HO. Thermal and structural analyses combined with dielectric studies and optical observations revealed the structural phase transition at T = 339/340 K (I↔II) and T = 347/348 K (II↔III) on heating and cooling, respectively. Both phase transitions are of the first-order type. Read More

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Enhanced dielectric and conductivity properties of carbon-coated SiC nanocomposites in the terahertz frequency range.

Nanotechnology 2021 Apr 12;32(26):265705. Epub 2021 Apr 12.

Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Ministry of Education), School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, People's Republic of China.

C-coated SiC nanocomposites (SiC@C NCs) were one-step synthesized under a mixture atmosphere of Ar and CH using a DC arc-discharge plasma method. The microstructure of the composites could be controlled by varying the volume ratio of Ar and CH. A strong response to the terahertz (THz) field was observed due to the existence of a graphite shell. Read More

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Understanding ball milling mechanochemical processes with DFT calculations and microkinetic modeling.

ChemSusChem 2021 Apr 12. Epub 2021 Apr 12.

Institute of Chemical Research of Catalonia: Institut Catala d'Investigacio Quimica, -, SPAIN.

Mechanochemistry is an emerging field with many potential applications in sustainable chemistry. But despite the growing interest on the field, its underlying mechanistic foundations are not fully understood yet. This work presents the application of computational tools, such as DFT calculations in continuum and microkinetic modeling, to the analysis of mechanically activated procedures. Read More

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Reduced Graphene Oxide/FeO/Polyaniline Ternary Composites as a Superior Microwave Absorber in the Shielding of Electromagnetic Pollution.

ACS Omega 2021 Apr 22;6(13):9164-9175. Epub 2021 Mar 22.

Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721302, West Bengal, India.

The present work is focused on fabrication of reduced graphene oxide/iron(II/III) oxide/polyaniline (RGO/FeO/PANI) ternary composite by a hydrothermal method, its characterization, and application in the development of a high microwave absorbing shielding material. The RGO/FeO/PANI composite showed dramatic enhancement of dielectric loss and magnetic loss compared to FeO/PANI and RGO/FeO binary composites. This is ascribed to the embedment of more heterostructure phases. Read More

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Seeded Growth of Ultrathin Carbon Films Directly onto Silicon Substrates.

ACS Omega 2021 Apr 24;6(13):8829-8836. Epub 2021 Mar 24.

School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia.

The production of graphene films is of importance for the large-scale application of graphene-based materials; however, there is still a lack of an efficient and effective approach to synthesize graphene films directly on dielectric substrates. Here, we report the controlled growth of ultrathin carbon films, which have a similar structure to graphene, directly on silicon substrates in a process of seeded chemical vapor deposition (CVD). Crystalline silicon with a thermally grown 300 nm oxide layer was first treated with 3-trimethoxysilyl-1-propanamine (APS), which was used as an anchor point for the covalent deposition of small graphene flakes, obtained from graphite using the Hummers' method. Read More

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Fano resonance and polarization transformation induced by interpolarization coupling of Bloch surface waves.

Phys Rev B 2019 Mar;99(11)

Institute of Photonics, Department of Optics and Optical Engineering, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China.

In this work, the resonant coupling behaviors between the transverse-electric (TE) and transverse-magnetic (TM) Bloch surface waves (BSWs) on a dielectric multilayer have been theoretically studied. Due to the different penetration depths in the dielectric multilayer, the TM BSWs and TE BSWs can act as the radiative and dark electromagnetic modes, respectively. By using a rectangular grating on the dielectric multilayer, both Rabi splitting and Fano resonance phenomena based on the coupling of the two BSW modes were demonstrated, through tuning the period of the grating and the azimuthal angle of the incoming wave. Read More

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New Cationic -[Re(CO)(deeb)B2] Complex, Where B2 Is a Benzimidazole Derivative, as a Potential New Luminescent Dye for Proteins Separated by SDS-PAGE.

Front Chem 2021 25;9:647816. Epub 2021 Mar 25.

Laboratorio de Genética y Patogénesis Bacteriana, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile.

Sodium-dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE) can be used to separate proteins based mainly on their size such as in denaturing gels. Different staining methods have been reported to observe proteins in the gel matrix, where the most used dyes are generally anionic. Anionic dyes allow for interactions with protonated amino acids, retaining the dye in the proteins. Read More

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Performance matching between the surface structure of cucumber powdery mildew in different growth stages and the properties of surfactant solution.

Pest Manag Sci 2021 Apr 9. Epub 2021 Apr 9.

College of Chemistry and Materials Science, Shandong Agricultural University, Tai'an, Shandong, 271018, People's Republic of China.

Background: Understanding the performance matching of pesticide droplets on surface of cucumber leaves modified by powdery mildew is of practical importance for the agricultural sector. Herein, the surface texture and wettability of cucumber leaves covered by powdery mildew were systematically examined using parameters such as micromorphology, physicochemical properties and liquid droplet contact angle measurements.

Results: Our results show that powdery mildew growth can be divided into four distinct stages according to the surface texture characteristics of the diseased cucumber leaves. Read More

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Directional Modulation of Exciton Emission Using Single Dielectric Nanospheres.

Adv Mater 2021 Apr 9:e2007236. Epub 2021 Apr 9.

Walker Department of Mechanical Engineering and Texas Materials Institute, The University of Texas at Austin, Austin, TX, 78712, USA.

Coupling emitters with nanoresonators is an effective strategy to control light emission at the subwavelength scale with high efficiency. Low-loss dielectric nanoantennas hold particular promise for this purpose, owing to their strong Mie resonances. Herein, a highly miniaturized platform is explored for the control of emission based on individual subwavelength Si nanospheres (SiNSs) to modulate the directional excitation and exciton emission of 2D transition metal dichalcogenides (2D TMDs). Read More

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Hollow Electrode Capillary Plasma Ionization Source for Rapid On-line Detection of Gaseous Samples.

Rapid Commun Mass Spectrom 2021 Apr 9:e9099. Epub 2021 Apr 9.

Key Laboratory of Advanced Mass Spectrometry and Molecular Analysis of Zhejiang Province, Institute of Mass Spectrometry, Ningbo University, Ningbo, 315211, China.

Rationale: Gas Chromatography Mass Spectrometry (GC-MS) with electron ionization (EI)is the most widely used analysis technique of gaseous samples, but it may be time-consuming for on-line monitoring of mixtures whose concentrations relatively change rapidly. On the other hand, current ionization methods, such as chemical ionization (CI) and proton transfer reaction (PTR), also have some disadvantages such as selectivity. Appropriate soft ionization sources therefore are searched for rapid on-line detection. Read More

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Magneto-optical effects in hyperbolic metamaterials based on ordered arrays of bisegmented gold/nickel nanorods.

Nanotechnology 2021 Apr 9. Epub 2021 Apr 9.

Physics, Moscow State University, Moskva, RUSSIAN FEDERATION.

Hyperbolic metamaterials (HMM) based on multilayered metal/dielectric films or ordered arrays of metal nanorods in dielectric matrix are extremely attractive optical materials for manipulating over the parameters of the light flow. One of the most promising tools for tuning the optical properties of metamaterials in situ is application of external magnetic field. However, for the case of HMM based on the ordered arrays of magneto-plasmonic nanostructures, this effect has not been clearly demonstrated up to now. Read More

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Dielectric Engineered Two-Dimensional Neuromorphic Transistors.

Nano Lett 2021 Apr 9. Epub 2021 Apr 9.

Department of Chemistry, National University of Singapore, Singapore 117543, Singapore.

Two-dimensional (2D) materials, which exhibit planar-wafer technique compatibility and pure electrically triggered communication, have established themselves as potential candidates in neuromorphic architecture integration. However, the current 2D artificial synapses are mainly realized at a single-device level, where the development of 2D scalable synaptic arrays with complementary metal-oxide-semiconductor compatibility remains challenging. Here, we report a 2D transition metal dichalcogenide-based synaptic array fabricated on commercial silicon-rich silicon nitride (sr-SiN) substrate. Read More

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Structure and Microwave Dielectric Properties of Gillespite-Type ACuSiO (A = Ca, Sr, Ba) Ceramics and Quantitative Prediction of the × Value via Machine Learning.

ACS Appl Mater Interfaces 2021 Apr 9. Epub 2021 Apr 9.

School of Engineering, RMIT University, Melbourne, VIC 3001, Australia.

Structure and dielectric properties of gillespite-type ceramics ACuSiO (A = Ca, Sr, Ba) were investigated by crystal structure refinement, far-infrared reflectivity spectroscopy, and microwave dielectric measurements. A series of (CaSr)CuSiO (0 < < 1) ceramics with relative permittivities of 5.70-5. Read More

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Self-Isolated Raman Lasing with a Chiral Dielectric Metasurface.

Phys Rev Lett 2021 Mar;126(12):123201

Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA.

The light sources that power photonic networks are small and scalable, but they also require the incorporation of optical isolators that allow light to pass in one direction only, protecting the light source from damaging backreflections. Unfortunately, the size and complex integration of optical isolators makes small-scale and densely integrated photonic networks infeasible. Here, we overcome this limitation by designing a single device that operates both as a coherent light source and as its own optical isolator. Read More

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Spectral Reflectometry in Biomedical Imaging and Sensing.

Adv Exp Med Biol 2021 ;1310:367-383

School of Biological Sciences, Seoul National University, Seoul, South Korea.

Spectral reflectometry is a spectroscopic measurement technique based on thin-film interference, which has been widely applied in industries to measure thicknesses of thin dielectric layers at the nanoscale. Recent advances in the understanding of biological nanostructures have opened a new field of spectral reflectometry in biomedicine from molecular level sensing to biomedical imaging. This chapter comprehensively covers the relevant topics on spectral reflectometry in biomedicine from its principle to applications. Read More

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Excitonic effects in the optical spectra of LiSiO compound.

Sci Rep 2021 Apr 8;11(1):7683. Epub 2021 Apr 8.

Department of Physics, National Cheng Kung University, 70101, Tainan, Taiwan.

LiSiO compound exhibits unique electronic and optical properties. The state-of-the-art analyses, which based on first-principle calculations, have successfully confirmed the concise physical/chemical picture and the orbital bonding in Li-O and Si-O bonds. Especially, the unusual optical response behavior includes a large red shift of the onset frequency due to the extremely strong excitonic effect, the polarization of optical properties along three-directions, various optical excitations structures and the most prominent plasmon mode in terms of the dielectric functions, energy loss functions, absorption coefficients and reflectance spectra. Read More

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Development and characterization of NbSn/AlO superconducting multilayers for particle accelerators.

Sci Rep 2021 Apr 8;11(1):7770. Epub 2021 Apr 8.

Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA.

Superconducting radio-frequency (SRF) resonator cavities provide extremely high quality factors > 10 at 1-2 GHz and 2 K in large linear accelerators of high-energy particles. The maximum accelerating field of SRF cavities is limited by penetration of vortices into the superconductor. Present state-of-the-art Nb cavities can withstand up to 50 MV/m accelerating gradients and magnetic fields of 200-240 mT which destroy the low-dissipative Meissner state. Read More

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Low-loss metasurface optics down to the deep ultraviolet region.

Light Sci Appl 2020 Apr 9;9(1):55. Epub 2020 Apr 9.

Physical Measurement Laboratory, National Institute of Standards and Technology, 20899, Gaithersburg, MD, USA.

Shrinking conventional optical systems to chip-scale dimensions will benefit custom applications in imaging, displaying, sensing, spectroscopy, and metrology. Towards this goal, metasurfaces-planar arrays of subwavelength electromagnetic structures that collectively mimic the functionality of thicker conventional optical elements-have been exploited at frequencies ranging from the microwave range up to the visible range. Here, we demonstrate high-performance metasurface optical components that operate at ultraviolet wavelengths, including wavelengths down to the record-short deep ultraviolet range, and perform representative wavefront shaping functions, namely, high-numerical-aperture lensing, accelerating beam generation, and hologram projection. Read More

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Bayesian unsupervised learning reveals hidden structure in concentrated electrolytes.

J Chem Phys 2021 Apr;154(13):134902

Department of Physics, University of Cambridge, CB3 0HE Cambridge, United Kingdom.

Electrolytes play an important role in a plethora of applications ranging from energy storage to biomaterials. Notwithstanding this, the structure of concentrated electrolytes remains enigmatic. Many theoretical approaches attempt to model the concentrated electrolyte by introducing the idea of ion pairs, with ions either being tightly "paired" with a counter-ion or "free" to screen charge. Read More

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Accuracy trade-off between one-electron and excitonic spectra of cuprous halides in first-principles calculations.

J Chem Phys 2021 Apr;154(13):134704

State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China.

Because of the sophisticated error cancellation in the density functional theory (DFT)-based calculations, a theoretically more accurate input would not guarantee a better output. In this work, our first-principles GW plus Bethe-Salpeter equation calculations using pseudopotentials show that cuprous halides (CuCl and CuBr) are such extreme cases for which a better one-electron band is not accompanied with a better exciton binding energy. Moreover, we find that the exchange interaction of Cu core electrons plays a crucial role in their ground-state electronic properties, especially in the energy gap and macroscopic dielectric constant. Read More

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Generic Structural Relaxation in Supercooled Liquids.

J Phys Chem Lett 2021 Apr 8:3685-3690. Epub 2021 Apr 8.

Institute of Condensed Matter Physics, Technical University of Darmstadt, 64289 Darmstadt, Germany.

One of the unsolved problems of dynamics in supercooled liquids are the differences in spectral shape of the structural relaxation observed among different methods and substances, and a possible generic line shape has long been debated. We show that the light scattering spectra of very different systems, e.g. Read More

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Diversity-oriented synthesis of polymer membranes with ion solvation cages.

Nature 2021 Apr 7;592(7853):225-231. Epub 2021 Apr 7.

Joint Center for Energy Storage Research, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.

Microporous polymers feature shape-persistent free volume elements (FVEs), which are permeated by small molecules and ions when used as membranes for chemical separations, water purification, fuel cells and batteries. Identifying FVEs that have analyte specificity remains a challenge, owing to difficulties in generating polymers with sufficient diversity to enable screening of their properties. Here we describe a diversity-oriented synthetic strategy for microporous polymer membranes to identify candidates featuring FVEs that serve as solvation cages for lithium ions (Li). Read More

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Synthesis and characterization of Mg-Zn ferrite based flexible microwave composites and its application as SNG metamaterial.

Sci Rep 2021 Apr 7;11(1):7654. Epub 2021 Apr 7.

Department of Electrical Engineering, Qatar University, 2713, Doha, Qatar.

In this article, we propose SNG (single negative) metamaterial fabricated on Mg-Zn ferrite-based flexible microwave composites. Firstly, the flexible composites are synthesized by the sol-gel method having four different molecular compositions of MgZnFeO which are denoted as Mg, Mg Mg and Mg. The structural, morphological, and microwave properties of the synthesized flexible composites are analyzed using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and conventional dielectric assessment kit (DAK) to justify their possible application as dielectric substrate at microwave frequency regime. Read More

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