Self-assembled Nano-layering at the Adhesive Interface

2012 ◽  
Vol 91 (4) ◽  
pp. 376-381 ◽  
Author(s):  
Y. Yoshida ◽  
K. Yoshihara ◽  
N. Nagaoka ◽  
S. Hayakawa ◽  
Y. Torii ◽  
...  
Keyword(s):  
Adhesive Layer ◽  
Dihydrogen Phosphate ◽  
X Ray Diffraction ◽  
Hybrid Layer ◽  
Functional Monomers ◽  
X Ray ◽  
Adhesive Interface ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Self Assembled

According to the ‘Adhesion–Decalcification’ concept, specific functional monomers within dental adhesives can ionically interact with hydroxyapatite (HAp). Such ionic bonding has been demonstrated for 10-methacryloyloxydecyl dihydrogen phosphate (MDP) to manifest in the form of self-assembled ‘nano-layering’. However, it remained to be explored if such nano-layering also occurs on tooth tissue when commercial MDP-containing adhesives (Clearfil SE Bond, Kuraray; Scotchbond Universal, 3M ESPE) were applied following common clinical application protocols. We therefore characterized adhesive-dentin interfaces chemically, using x-ray diffraction (XRD) and energy-dispersive x-ray spectroscopy (EDS), and ultrastructurally, using (scanning) transmission electron microscopy (TEM/STEM). Both adhesives revealed nano-layering at the adhesive interface, not only within the hybrid layer but also, particularly for Clearfil SE Bond (Kuraray), extending into the adhesive layer. Since such self-assembled nano-layering of two 10-MDP molecules, joined by stable MDP-Ca salt formation, must make the adhesive interface more resistant to biodegradation, it may well explain the documented favorable clinical longevity of bonds produced by 10-MDP-based adhesives.

Phase Transformation of Powdered Material by Using Metal Jet

2012 ◽  
Vol 706-709 ◽  
pp. 741-744 ◽  
Author(s):  
Akio Kira ◽  
Ryuichi Tomoshige ◽  
Kazuyuki Hokamoto ◽  
Masahiro Fujita
Keyword(s):  
Phase Transformation ◽  
Powdered Material ◽  
Scanning Transmission Electron Microscope ◽  
Ultrahigh Pressure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Metal Jet ◽  
Very High

The various techniques of phase transformation of the material have been proposed by many researchers. We have developed several devices to generate the ultrahigh pressure by using high explosive. One of them uses metal jets. It is expected that the ultrahigh pressure occurs by the head-on collision between metal jets, because the velocity of the metal jet is very high. By mixing a powdered material with metal jets, the pressure of the material becomes high. The purpose of this study is to transform the phase of the powdered material by using this high pressure. The powders of the graphite and hBN were applied. The synthesis to the diamond and cBN was confirmed by X-ray diffraction (XRD). In this paper, the mechanism of the generation of the ultrahigh pressure is explained and the results of the observation of the powder by using scanning transmission electron microscope (STEM) are reported.

Core–shell structures with metallic silver as nucleation agent of low expansion phases in BaO/SrO/ZnO/SiO2 glasses

CrystEngComm ◽  
2019 ◽  
Vol 21 (29) ◽  
pp. 4373-4386 ◽  
Author(s):  
Christian Thieme ◽  
Michael Kracker ◽  
Katrin Thieme ◽  
Christian Patzig ◽  
Thomas Höche ◽  
...  
Keyword(s):  
Scanning Transmission Electron Microscopy ◽  
Nucleating Agent ◽  
Shell Structures ◽  
Metallic Silver ◽  
X Ray Diffraction ◽  
Nucleation Agent ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission

The role of silver as a nucleating agent in BaO/SrO/ZnO/SiO2 glasses is studied with a range of microstructure-characterization techniques, such as scanning transmission electron microscopy, ultraviolet-visible spectroscopy, and X-ray diffraction.

Obtaining the structure factors for an epitaxial film using Cu X-ray radiation

2013 ◽  
Vol 46 (6) ◽  
pp. 1749-1754 ◽  
Author(s):  
P. Wadley ◽  
A. Crespi ◽  
J. Gázquez ◽  
M.A. Roldán ◽  
P. García ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Thin Films ◽  
Structure Factor ◽  
Tetragonal Symmetry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Structure Factors ◽  
Scanning Transmission

Determining atomic positions in thin films by X-ray diffraction is, at present, a task reserved for synchrotron facilities. Here an experimental method is presented which enables the determination of the structure factor amplitudes of thin films using laboratory-based equipment (Cu Kα radiation). This method was tested using an epitaxial 130 nm film of CuMnAs grown on top of a GaAs substrate, which unlike the orthorhombic bulk phase forms a crystal structure with tetragonal symmetry. From the set of structure factor moduli obtained by applying this method, the solution and refinement of the crystal structure of the film has been possible. The results are supported by consistent high-resolution scanning transmission electron microscopy and stoichiometry analyses.

scholarly journals Synthesis and Structure of novel Luminescent lanthanide organic frameworks.

2014 ◽  
Vol 70 (a1) ◽  
pp. C1259-C1259
Author(s):  
Mohammed S. M. Abdelbaky ◽  
Zakariae Amghouz ◽  
Santiago Granda
Keyword(s):  
Thermal Analyses ◽  
Luminescence Properties ◽  
X Ray Diffraction ◽  
Hydrothermal Conditions ◽  
X Ray ◽  
Carboxylate Groups ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Conventional Electrode ◽  
Li Ion

Lanthanide-Organic frameworks (LnOFs) are currently attracting increasing attention due to their excellent luminescence properties, in which both Ln3+ and organic linkers can be used to give rise to luminescence materials with increased brightness and emission quantum yield [1,2]. Lithium doped MOFs are of particular interest due to the recent studies showing enhanced H2 uptake, as well as promising candidates for replacing the conventional electrode in Li-ion batteries [3,4]. Herein, novel Lithium-lanthanide frameworks based on a rigid dicarboxylic acid, formulated as [LiLn(BDC)2(H2O)·2(H2O)] (Ln = Y, Dy, Ho, Er, Yb, Y1-xEux, Y1-xTbx and H2BDC = Terephthalic acid), have been obtained as single phases under hydrothermal conditions. The crystal structures were solved by single-crystal X-ray diffraction and the bulk characterized by powder X-ray diffraction (PXRD), thermal analyses (TG-MS and DSC), vibrational spectroscopy (FTIR), scanning/transmission electron microscopy (SEM-EDX, TEM, SAED, STEM-EDX), and powder X-ray thermodiffractometry (HT-XRD). All compounds are isostructural (monoclinic P21/c, a = 11.6365(7) Å, b =16.0920(2) Å, c = 13.2243(8) Å and β = 132.23(1)° for Ln = Y [5]) and possess a 3D framework with 1D trigonal channels running along the [101] direction contain water molecules. The structure is built up of unusual four-membered rings formed by edge- and vertex-shared {LnO8} and {LiO4} polyhedra. The four-membered rings are isolated and connected to each other via carboxylate groups. Topologically, the 3D frameworks belongs to a new 2-nodal 3,10-c net with point symbol of {4.5^2}2{4^14.5^10.6^18.7.8^2}. HT-XRD reveals that the compounds undergo phase transformation upon dehydration process which is a reversible process involving a spontaneous rehydration characterized by fast kinetic. The luminescence properties of selected compounds are also studied.

scholarly journals MINERALOGICAL AND SPECTROSCOPIC STUDY OF NESQUEHONITE SYNTHESIZED BY REACTION OF GASEOUS CO2 WITH MG CHLORIDE SOLUTION

2017 ◽  
Vol 50 (4) ◽  
pp. 2009
Author(s):  
V. Skliros ◽  
A. Anagnostopoulou ◽  
P. Tsakiridis ◽  
M. Perraki
Keyword(s):  
Scanning Transmission Electron Microscopy ◽  
Chloride Solution ◽  
Raw Material ◽  
X Ray Diffraction ◽  
X Ray ◽  
Raman Spectroscopic ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Permanent Storage ◽  
Ir And Raman

Nesquehonite, a hydrous carbonate with promising uses such as building raw material and treatment of wastewaters, was synthesized under low pressure conditions by reaction of gaseous CO2 with Mg chloride solution and it was studied by means of X-Ray Diffraction, optical and scanning/transmission electron microscopy, and FTIR and Raman spectroscopic methods. Synthesized nesquehonite forms elongated fibers, exhibiting transparent to translucent diaphaneity and vitreous luster. It is characterized by high crystallinity. IR and Raman spectroscopy indicated the presence of OHand HCO3 - in the crystal structure of nesquehonite. The nesquehonite synthesis described herein constitutes a potential permanent storage of CO2 emissions.

scholarly journals New Insight on the Hydrogen Absorption Evolution of the Mg–Fe–H System under Equilibrium Conditions

Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 967 ◽  
Author(s):  
Julián Puszkiel ◽  
M. Castro Riglos ◽  
José Ramallo-López ◽  
Martin Mizrahi ◽  
Thomas Gemming ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Formation Mechanism ◽  
X Ray Diffraction ◽  
Equilibrium Conditions ◽  
Edge Structure ◽  
X Ray ◽  
Solid Diffusion ◽  
Transmission Electron ◽  
Scanning Transmission

Mg2FeH6 is regarded as potential hydrogen and thermochemical storage medium due to its high volumetric hydrogen (150 kg/m3) and energy (0.49 kWh/L) densities. In this work, the mechanism of formation of Mg2FeH6 under equilibrium conditions is thoroughly investigated applying volumetric measurements, X-ray diffraction (XRD), X-ray absorption near edge structure (XANES), and the combination of scanning transmission electron microscopy (STEM) with energy-dispersive X-ray spectroscopy (EDS) and high-resolution transmission electron microscopy (HR-TEM). Starting from a 2Mg:Fe stoichiometric powder ratio, thorough characterizations of samples taken at different states upon hydrogenation under equilibrium conditions confirm that the formation mechanism of Mg2FeH6 occurs from elemental Mg and Fe by columnar nucleation of the complex hydride at boundaries of the Fe seeds. The formation of MgH2 is enhanced by the presence of Fe. However, MgH2 does not take part as intermediate for the formation of Mg2FeH6 and acts as solid-solid diffusion barrier which hinders the complete formation of Mg2FeH6. This work provides novel insight about the formation mechanism of Mg2FeH6.

Optical And Structural properties of Vertical Aligned Self-Assembled InAs Quantum Dots Multilayers

2001 ◽  
Vol 676 ◽  
Author(s):  
J. C. González ◽  
M. I. N. da Silva ◽  
W. N. Rodrigues ◽  
F. M. Matinaga ◽  
R. Magalhaes-Paniago ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Structural Properties ◽  
Molecular Beam ◽  
X Ray Diffraction ◽  
Inas Quantum Dots ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Self Assembled

ABSTRACTIn this work, we report optical and structural properties of vertical aligned self-assembled InAs quantum dots multilayers. The InAs quantum dots samples were grown by Molecular Beam Epitaxy. Employing Atomic Force Microscopy, Transmission Electron Microscopy, and Gracing Incident X-ray Diffraction we have studied the structural properties of samples with different number of periods of the multiplayer structure, as well as different InAs coverage. The optical properties were studied using Photoluminescence spectroscopy.

The quasiperiodic average structure of highly disordered decagonal Zn–Mg–Dy and its temperature dependence

2014 ◽  
Vol 70 (2) ◽  
pp. 315-330 ◽  
Author(s):  
Taylan Ors ◽  
Hiroyuki Takakura ◽  
Eiji Abe ◽  
Walter Steurer
Keyword(s):  
Single Crystal ◽  
Decomposition Temperature ◽  
Dark Field ◽  
Penrose Tiling ◽  
X Ray Diffraction ◽  
Decagonal Quasicrystal ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Annular Dark Field

A single-crystal X-ray diffraction structure analysis of decagonal Zn–Mg–Dy, a Frank–Kasper-type quasicrystal, was performed using the higher-dimensional approach. For this first Frank–Kasper (F–K) decagonal quasicrystal studied so far, significant differences to the decagonal Al–TM-based (TM: transition metal) phases were found. A new type of twofold occupation domain is located on certain edge centers of the five-dimensional unit cell. The structure can be described in terms of a two-cluster model based on a decagonal cluster (∼ 23 Å diameter) arranged on the vertices of a pentagon-Penrose tiling (PPT) and a star-like cluster covering the remaining space. This model is used for the five-dimensional refinements, which converged to anRvalue of 0.126. The arrangement of clusters is significantly disordered as indicated by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). In order to check the structure and stability at higher temperatures,in-situhigh-temperature (HT) single-crystal X-ray diffraction experiments were conducted at 598 and 648 K (i.e.slightly below the decomposition temperature). The structure does not change significantly, however, the best quasiperiodic order is found at 598 K. The implication of these results on the stabilization mechanism of quasicrystals is discussed.

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