Chemical and Structural Analysis of Nitridated Sapphire

1997 ◽  
Vol 482 ◽  
Author(s):  
Y. Cho ◽  
S. Rouvimov ◽  
Y. Kim ◽  
Z. Liliental-Weber ◽  
E. R. Weber
Keyword(s):  
Electron Microscopy ◽  
Atomic Force Microscopy ◽  
Structural Analysis ◽  
Photoelectron Spectroscopy ◽  
High Resolution Electron Microscopy ◽  
Cross Sectional ◽  
Force Microscopy ◽  
Sapphire Substrates ◽  
Atomic Force ◽  
Resolution Electron

AbstractThe incorporation of nitrogen into sapphire substrates during nitridation was studied by xray photoelectron spectroscopy (XPS). An increase in the intensity of nitrogen 1s peak in XPS was observed upon longer nitridation. The surface morphology of the substrates was characterized by atomic force microscopy (AFM). High resolution electron microscopy (HREM) was employed for structural analysis. The cross sectional TEM showed a thin layer of AlN buried between amorphous AlNxO1−x and sapphire. This is the first direct observation of AlN on sapphire. The TEM images show a deeper penetration depth of nitrogen into a longer nitridated sapphire.

scholarly journals Structural identification of individual helical amyloid filaments by integration of cryo-electron microscopy-derived maps in comparative morphometric atomic force microscopy image analysis

2021 ◽  
Author(s):  
Liisa Lutter ◽  
Youssra Al-Hilaly ◽  
Christopher J. Serpell ◽  
Mick F. Tuite ◽  
Claude M. Wischik ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Atomic Force Microscopy ◽  
Image Analysis ◽  
Structural Analysis ◽  
Amyloid Fibrils ◽  
Structural Identification ◽  
Force Microscopy ◽  
Atomic Force ◽  
Cryo Electron Microscopy

The presence of amyloid fibrils is a hallmark of more than 50 human disorders, including neurodegenerative diseases and systemic amyloidoses. A key unresolved challenge in understanding the involvement of amyloid in disease is to explain the relationship between individual structural polymorphs of amyloid fibrils, in potentially mixed populations, and the specific pathologies with which they are associated. Although cryo-electron microscopy (cryo-EM) and solid-state nuclear magnetic resonance (ssNMR) spectroscopy methods have been successfully employed in recent years to determine the structures of amyloid fibrils with high resolution detail, they rely on ensemble averaging of fibril structures in the entire sample or significant subpopulations. Here, we report a method for structural identification of individual fibril structures imaged by atomic force microscopy (AFM) by integration of high-resolution maps of amyloid fibrils determined by cryo-EM in comparative AFM image analysis. This approach was demonstrated using the hitherto structurally unresolved amyloid fibrils formed in vitro from a fragment of tau (297-391), termed 'dGAE'. Our approach established unequivocally that dGAE amyloid fibrils bear no structural relationship to heparin-induced tau fibrils formed in vitro. Furthermore, our comparative analysis resulted in the prediction that dGAE fibrils are closely related structurally to the paired helical filaments (PHFs) isolated from Alzheimer's disease (AD) brain tissue characterised by cryo-EM. These results show the utility of individual particle structural analysis using AFM, provide a workflow of how cryo-EM data can be incorporated into AFM image analysis and facilitate an integrated structural analysis of amyloid polymorphism.

Template Assisted Ni Nanowires Fabrication

2019 ◽  
Vol 946 ◽  
pp. 235-241 ◽  
Author(s):  
D.I. Tishkevich ◽  
A.I. Vorobjova ◽  
D.A. Vinnik
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Atomic Force Microscopy ◽  
Structural Analysis ◽  
Specific Magnetization ◽  
X Ray ◽  
Force Microscopy ◽  
Alumina Membranes ◽  
Atomic Force ◽  
Scanning Electron

Through-pores alumina membranes of 50 μm thickness and 70 × 70 mm size have been fabricated to deposit Ni nanowires by electrochemical processing. Due to highly ordered microstructure of the membranes, the pores were filled by nanowires almost to 100%. The membrane nanowires composite morphology; structure and chemical features have been studied by scanning electron microscopy, atomic-force microscopy and X-ray structural analysis. To measure the specific magnetization σ as a function of temperature in the range of 77–1400 K, the pondero-motive method was used.

Dislocation reduction with quantum dots in GaN grown on sapphire substrates by molecular beam epitaxy

2002 ◽  
Vol 722 ◽  
Author(s):  
David J. Smith ◽  
Daming Huang ◽  
Michael A Reshchikov ◽  
Feng Yun ◽  
T. King ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Atomic Force Microscopy ◽  
Molecular Beam ◽  
Buffer Layers ◽  
Force Microscopy ◽  
Sapphire Substrates ◽  
Atomic Force ◽  
Transmission Electron ◽  
Aln Buffer

AbstractWe have investigated a novel approach for improving GaN crystal quality by utilizing a stack of quantum dots (QDs) in GaN grown on sapphire substrates by molecular beam epitaxy. The GaN films were grown on GaN/AlN buffer layers containing multiple QDs and characterized using x-ray diffraction, photoluminescence, atomic force microscopy, and transmission electron microscopy. The density of the dislocations in the films was determined by defect delineation wet chemical etching and atomic force microscopy. It was found that the insertion of a set of multiple GaN QD layers in the buffer layer effectively reduced the density of the dislocations in the epitaxial layers. As compared to a density of ∼1010cm-2in typical GaN films grown on AlN buffer layers, a density of ∼3×107cm-2was demonstrated in GaN films grown with the QD layers. Transmission electron microscopy observations confirmed termination of threading dislocations by the QD layers.

High Resolution Electron Microscopy Studies of Interfaces Between Al203 Substrates and MBE Grown NB Films

1990 ◽  
Vol 209 ◽  
Author(s):  
J. Mayer ◽  
J. Dura ◽  
C.P. Flynn ◽  
M. RüHle
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Metal Film ◽  
Molecular Beam ◽  
High Resolution Electron Microscopy ◽  
Cross Sectional ◽  
Sapphire Substrates ◽  
Resolution Electron ◽  
20 Nm ◽  
Atomistic Structure

ABSTRACTSingle crystal niobium films were grown by Molecular Beam Epitaxy (MBE) on (0001)s sapphire substrates. Cross-sectional specimens with thickness of <20 nm were prepared so that the Nb/A1203 interface could be investigated by high resolutionelectron microscopy (HREM). The orientation relationship between the metal film and the ceramic substrate was verified by selected area diffraction: (111)Nb ║(0001)S and [110]Nb║[2110]S. The atomistic structure of the interface was identified by HREM.

scholarly journals Fast and Straightforward Synthesis of Luminescent Titanium(IV) Dioxide Quantum Dots

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Václav Štengl ◽  
Jiří Henych ◽  
Martin Šťastný ◽  
Martin Kormunda
Keyword(s):  
Quantum Dots ◽  
Photoelectron Spectroscopy ◽  
High Resolution Electron Microscopy ◽  
Fast Method ◽  
X Ray ◽  
Force Microscopy ◽  
Selected Area Electron Diffraction ◽  
Atomic Force ◽  
Resolution Electron ◽  
Close Range

The nucleus of titania was prepared by reaction of solution titanium oxosulphate with hydrazine hydrate. These titania nuclei were used for titania quantum dots synthesis by a simple and fast method. The prepared titanium(IV) dioxide quantum dots were characterized by measurement of X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), high-resolution electron microscopy (HRTEM), and selected area electron diffraction (SAED). The optical properties were determined by photoluminescence (PL) spectra. The prepared titanium(IV) dioxide quantum dots have the narrow range of UV excitation (365–400 nm) and also a close range of emission maxima (450–500 nm).

Structural analysis of the surface-layer protein of spirillum serpens by high-resolution electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 738-739
Author(s):  
W. H. Wu ◽  
R. M. Glaeser
Keyword(s):  
Electron Microscopy ◽  
Surface Layer ◽  
Structural Analysis ◽  
High Resolution ◽  
Low Dose ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Surface Layer Protein ◽  
Morphological Unit ◽  
Resolution Electron

Spirillum serpens possesses a surface layer protein which exhibits a regular hexagonal packing of the morphological subunits. A morphological model of the structure of the protein has been proposed at a resolution of about 25 Å, in which the morphological unit might be described as having the appearance of a flared-out, hollow cylinder with six ÅspokesÅ at the flared end. In order to understand the detailed association of the macromolecules, it is necessary to do a high resolution structural analysis. Large, single layered arrays of the surface layer protein have been obtained for this purpose by means of extensive heating in high CaCl2, a procedure derived from that of Buckmire and Murray. Low dose, low temperature electron microscopy has been applied to the large arrays.As a first step, the samples were negatively stained with neutralized phosphotungstic acid, and the specimens were imaged at 40,000 magnification by use of a high resolution cold stage on a JE0L 100B. Low dose images were recorded with exposures of 7-9 electrons/Å2. The micrographs obtained (Fig. 1) were examined by use of optical diffraction (Fig. 2) to tell what areas were especially well ordered.

scholarly journals Corrosion Behavior and Mechanical Properties of a Nanocomposite Superhydrophobic Coating

Coatings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 652
Author(s):  
Divine Sebastian ◽  
Chun-Wei Yao ◽  
Lutfun Nipa ◽  
Ian Lian ◽  
Gary Twu
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Atomic Force Microscopy ◽  
Nanocomposite Coating ◽  
Superhydrophobic Coating ◽  
Force Microscopy ◽  
Atomic Force ◽  
Microscopy Images ◽  
Scanning Electron

In this work, a mechanically durable anticorrosion superhydrophobic coating is developed using a nanocomposite coating solution composed of silica nanoparticles and epoxy resin. The nanocomposite coating developed was tested for its superhydrophobic behavior using goniometry; surface morphology using scanning electron microscopy and atomic force microscopy; elemental composition using energy dispersive X-ray spectroscopy; corrosion resistance using atomic force microscopy; and potentiodynamic polarization measurements. The nanocomposite coating possesses hierarchical micro/nanostructures, according to the scanning electron microscopy images, and the presence of such structures was further confirmed by the atomic force microscopy images. The developed nanocomposite coating was found to be highly superhydrophobic as well as corrosion resistant, according to the results from static contact angle measurement and potentiodynamic polarization measurement, respectively. The abrasion resistance and mechanical durability of the nanocomposite coating were studied by abrasion tests, and the mechanical properties such as reduced modulus and Berkovich hardness were evaluated with the aid of nanoindentation tests.

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