Disordered photonics behavior from terahertz to ultraviolet of a three-dimensional graphene network

AbstractThe diffusion of light by random materials is a general phenomenon that appears in many different systems, spanning from colloidal suspension in liquid crystals to disordered metal sponges and paper composed of random fibers. Random scattering is also a key element behind mimicry of several animals, such as white beetles and chameleons. Here, random scattering is related to micro and nanosized spatial structures affecting a broad electromagnetic region. In this work, we have investigated how random scattering modulates the optical properties, from terahertz to ultraviolet light, of a novel functional material, i.e., a three-dimensional graphene (3D Graphene) network based on interconnected high-quality two-dimensional graphene layers. Here, random scattering generates a high-frequency pass-filter behavior. The optical properties of these graphene structures bridge the nanoworld into the macroscopic world, paving the way for their use in novel optoelectronic devices.

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Synthesis of Graphene-ZnO Heterogeneous Nanostructures by Chemical Vapor Deposition

MRS Proceedings ◽

10.1557/opl.2011.1456 ◽

2011 ◽

Vol 1348 ◽

Author(s):

Jian Lin ◽

Miroslav Penchev ◽

Guoping Wang ◽

Rajat K Paul ◽

Jiebin Zhong ◽

...

Keyword(s):

Optical Properties ◽

Chemical Vapor Deposition ◽

Vapor Deposition ◽

Three Dimensional ◽

Chemical Vapor ◽

Building Blocks ◽

Zno Nanostructures ◽

Large Area ◽

Graphene Layers

ABSTRACTIn this work, we report the synthesis and characterization of three dimensional heterostructures graphene nanostructures (HGN) comprising continuous large area graphene layers and ZnO nanostructures, fabricated via chemical vapor deposition. Characterization of large area HGN demonstrates that it consists of 1-5 layers of graphene, and exhibits high optical transmittance and enhanced electrical conductivity. Electron microscopy investigation of the three dimensional heterostructures shows that the morphology of ZnO nanostructures is highly dependent on the growth temperature. It is observed that ordered crystalline ZnO nanostructures are preferably grown along the <0001> direction. Ultraviolet spectroscopy indicates that the CVD grown HGN layers has excellent optical properties. A combination of electrical and optical properties of graphene and ZnO building blocks in ZnO based HGN provides unique characteristics for opportunities in future optoelectronic devices.

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A new approach to construct three dimensional segregated graphene structures in rubber composites for enhanced conductive, mechanical and barrier properties

Journal of Materials Chemistry C ◽

10.1039/c5tc04376j ◽

2016 ◽

Vol 4 (12) ◽

pp. 2353-2358 ◽

Cited By ~ 43

Author(s):

Yong Lin ◽

Shuqi Liu ◽

Lan Liu

Keyword(s):

Three Dimensional ◽

Barrier Properties ◽

Construction Method ◽

Rubber Composites ◽

New Approach ◽

3D Graphene ◽

Conductive Rubber ◽

First Time ◽

Graphene Structures

A novel pre-construction method was reported for the first time to fabricate conductive rubber composites with a conductive 3D-graphene segregated network.

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Facile Fabrication of Ultralow-Density Transparent Boehmite Nanofiber Cryogel Monoliths and Their Application in Volumetric Three-Dimensional Displays

10.26434/chemrxiv.5373835.v1 ◽

2017 ◽

Author(s):

Gen Hayase ◽

Takuya Funatomi ◽

Kota Kumagai

Keyword(s):

Image Processing ◽

Optical Properties ◽

Bulk Density ◽

Freeze Drying ◽

Three Dimensional ◽

Supercritical Drying ◽

Functional Material ◽

3D Displays ◽

Facile Fabrication ◽

Low Refractive Index

Low bulk density transparent porous monoliths have unique optical properties such as low refractive index and usually can be obtained via supercritical drying to prevent deformation and collapse of pore structure. We succeeded in fabricating a transparent cryogel with a bulk density of 3.5 mg cm<sup>−3</sup> by vacuum freeze drying of a monolithic wet gel composed of boehmite nanofibers. In the case of adding a functional material into the starting sol of the gel, a composite material can be obtained. We analyzed the optical properties of transparent cryogels using image processing (direct-global separation) and applied the composite with a fluorescent molecule to volumetric three-dimensional (3D) displays.

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Facile Fabrication of Ultralow-Density Transparent Boehmite Nanofiber Cryogel Monoliths and Their Application in Volumetric Three-Dimensional Displays

10.26434/chemrxiv.5373835 ◽

2017 ◽

Author(s):

Gen Hayase ◽

Takuya Funatomi ◽

Kota Kumagai

Keyword(s):

Image Processing ◽

Optical Properties ◽

Bulk Density ◽

Freeze Drying ◽

Three Dimensional ◽

Supercritical Drying ◽

Functional Material ◽

3D Displays ◽

Facile Fabrication ◽

Low Refractive Index

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Enhancing SNR and generating contrast for cryo-EM images with convolutional neural networks

10.1101/2020.08.16.253070 ◽

2020 ◽

Author(s):

Eugene Palovcak ◽

Daniel Asarnow ◽

Melody G. Campbell ◽

Zanlin Yu ◽

Yifan Cheng

Keyword(s):

Image Processing ◽

High Frequency ◽

Signal To Noise Ratio ◽

Three Dimensional ◽

Low Frequency ◽

Pass Filter ◽

Low Pass Filter ◽

Processing Pipeline ◽

Visual Contrast ◽

Low Pass

AbstractIn cryogenic electron microscopy (cryo-EM) of radiation-sensitive biological samples, both the signal-to-noise ratio (SNR) and the contrast of images are critically important in the image processing pipeline. Classic methods improve low-frequency image contrast experimentally, by imaging with high defocus, or computationally, by applying various types of low-pass filter. These contrast improvements typically come at the expense of high-frequency SNR, which is suppressed by high-defocus imaging and removed by low pass filtration. Here, we demonstrate that a convolutional neural network (CNN) denoising algorithm can be used to significantly enhance SNR and generate contrast in cryo-EM images. We provide a quantitative evaluation of bias introduced by the denoising procedure and its influences on image processing and three-dimensional reconstructions. Our study suggests that besides enhancing the visual contrast of cryo-EM images, the enhanced SNR of denoised images may facilitate better outcomes in the other parts of the image processing pipeline, such as classification and 3D alignment. Overall, our results provide a ground of using denoising CNNs in the cryo-EM image processing pipeline.

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Three-dimensional acetylenic modified graphene for high-performance optoelectronics and topological materials

npj Computational Materials ◽

10.1038/s41524-021-00579-5 ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Yan Gao ◽

Chengyong Zhong ◽

Shengyuan A. Yang ◽

Kai Liu ◽

Zhong-Yi Lu

Keyword(s):

High Performance ◽

Materials Science ◽

Three Dimensional ◽

3D Graphene ◽

Graphene Layers ◽

Carbon Allotropes ◽

Topological Materials ◽

Topological States ◽

Direct Band ◽

Modified Graphene

AbstractSeeking carbon phases with versatile properties is one of the fundamental goals in physics, chemistry, and materials science. Here, based on the first-principles calculations, a family of three-dimensional (3D) graphene networks with abundant and fabulous electronic properties, including rarely reported dipole-allowed truly direct band gap semiconductors with suitable band gaps (1.07–1.87 eV) as optoelectronic/photovoltaic materials and topological nodal-ring semimetals, are proposed through stitching different graphene layers with acetylenic linkages. Remarkably, the optical absorption coefficients in some of those semiconducting carbon allotropes express possibly the highest performance among all of the semiconducting carbon phases known to date. On the other hand, the topological states in those topological nodal-ring semimetals are protected by the time-reversal and spatial symmetry and present nodal rings and nodal helical loops topological patterns. Those newly revealed carbon phases possess low formation energies and excellent thermodynamic stabilities; thus, they not only host a great potential in the application of optoelectronics, photovoltaics, and quantum topological materials etc., but also can be utilized as catalysis, molecule sieves or Li-ion anode materials and so on. Moreover, the approach used here to design novel carbon allotropes may also give more enlightenments to create various carbon phases with different applications.

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Density-based discrimination of protein and RNA in the ribosome

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100122721 ◽

1992 ◽

Vol 50 (1) ◽

pp. 464-465

Author(s):

Joachim Frank

Keyword(s):

Transfer Function ◽

Spatial Frequency ◽

Three Dimensional ◽

Wiener Filter ◽

Dark Field Image ◽

Dark Field ◽

Frequency Range ◽

Bright Field ◽

Contrast Transfer Function ◽

Pass Filter

Cryo-electron microscopy combined with single-particle reconstruction techniques has allowed us to form a three-dimensional image of the Escherichia coli ribosome.In the interior, we observe strong density variations which may be attributed to the difference in scattering density between ribosomal RNA (rRNA) and protein. This identification can only be tentative, and lacks quantitation at this stage, because of the nature of image formation by bright field phase contrast. Apart from limiting the resolution, the contrast transfer function acts as a high-pass filter which produces edge enhancement effects that can explain at least part of the observed variations. As a step toward a more quantitative analysis, it is necessary to correct the transfer function in the low-spatial-frequency range. Unfortunately, it is in that range where Fourier components unrelated to elastic bright-field imaging are found, and a Wiener-filter type restoration would lead to incorrect results. Depending upon the thickness of the ice layer, a varying contribution to the Fourier components in the low-spatial-frequency range originates from an “inelastic dark field” image. The only prospect to obtain quantitatively interpretable images (i.e., which would allow discrimination between rRNA and protein by application of a density threshold set to the average RNA scattering density may therefore lie in the use of energy-filtering microscopes.

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