Search results for "Microscopy"

Structure analysis of side chain liquid crystal polymer films by means of electron microscopy

1987

Abstract Using the combined techniques of electron diffraction, bright and dark field electron microscopy as well as light microscopy, it has been possible to obtain detailed structural information about the arrangement of the smectic layers in a polymethacrylate side chain liquid crystal polymer with a biphenylester as the mesogenic group.

Preparation of magnetic composites of MIL-53(Fe) or MIL-100(Fe) via partial transformation of their framework into γ-Fe2O3

2016

A novel two-step approach is proposed to obtain magnetically active composite materials consisting of MIL-53(Fe) or MIL-100(Fe) and γ-Fe2O3 particles. The first step consists in a partial transformation of the framework into a layer of γ-FeO(OH) (lepidocrocite) covering the MOF particles. We found that such a transformation can be realized under air-free conditions by hydrolysing the MOFs at pH 6.2 in the presence of FeSO4. In the second step the obtained γ-FeO(OH)/MOF composite is heated under an air flow at 250 °C in order to transform γ-FeO(OH) to γ-Fe2O3. The thus prepared composites containing 40 wt% of the magnetic phase were characterized in detail by XRD, HRTEM, FESEM, N2 adsorption…

Memory effects in MOS capacitors with silicon quantum dots

2001

To form crystalline Si dots embedded in SiO2, we have deposited thin films of silicon-rich oxide (SRO) by plasma-enhanced chemical vapor deposition of SiH4 and O2. Then the materials have been annealed in N2 ambient at temperatures between 950°C and 1100°C. Under such processing, the supersaturation of Si in the amorphous SRO film produces the formation of crystalline Si dots embedded in SiO2. The narrow dot size distributions, analyzed by transmission electron microscopy, are characterized by average grain radii and standard deviations down to about 1 nm. The memory functions of such structures has been investigated in MOS capacitors with a SRO film sandwiched between two thin SiO2 layers …

Incremental lines in root cementum of human teeth: an approach to their ultrastructural nature by microscopy.

1998

In ground sections of human teeth, root cementum shows under the light microscope as alternating, almost concentric, dark and light rings. In paleontology and forensic medicine, the number of these incremental lines or annulations is used to derive the age-at-death of the individual. To find the ultrastructural features underlying these cemental annulations, we used bright-field light microscopy (LM), confocal laser scanning microscopy (CLSM), transmission electron microscopy (TEM), and electron-dispersive x-radiation (EDX) in a scanning electron microscope (SEM). Annulations visible in ground sections of about 100-μm thickness were no longer visible in semi-thin sections (thickness, 1-2 μ…

Mikromorphometrie und Stereographie des Rauhtiefenreliefs beschichteter Implantatoberflächen durch Rasterelektronenmikroskopie und konfokale Laser-Sc…

1998

A biomimetic approach to ameliorate dental hypersensitivity by amorphous polyphosphate microparticles.

2016

Abstract Objective Dental hypersensitivity has become one of the most common and most costly diseases in the world, even though those maladies are very rarely life threatening. Using amorphous microparticles, fabricated from the natural polymer (polyphosphate), we intend to reseal the dentinal tubules exposed and reduce by that the hypersensitivity. Methods Amorphous microparticles (termed aCa-polyP-MP) were prepared from Na-polyphosphate (polyP) and CaCl 2 , then incubated with human teeth. The potential of the microparticles to plug the dentinal tubules was determined by microscopic and spectroscopic techniques. Results We demonstrate that, in contrast to polyP, the aCa-polyP-MP efficient…

Chemically Selective Imaging of Individual Bonds through Scanning Electron Energy-Loss Spectroscopy: Disulfide Bridges Linking Gold Nanoclusters

2020

As proof-of-principle of chemically selective, spatially resolved imaging of individual bonds, we carry out electron energy-loss spectroscopy in a scanning transmission electron microscopy instrument on atomically precise, thiolate-coated gold nanoclusters linked with 5,5'-bis(mercaptomethyl)-2,2'-bipyridine dithiol ligands. The images allow the identification of bridging disulfide bonds (R-S-S-R) between clusters, and X-ray photoelectron spectra support the finding.

Deposition and characterization of cold sprayed nanocrystalline NiTi

2011

International audience; Binary 50Ni–50Ti mixture was prepared by mechanical alloying from elemental powders. After 48 h of milling, the nanocrystalline B2-NiTi powder was produced. Then, this as-milled powder was deposited by cold spraying in order to produce a target which can be used to create thin films by magnetron sputtering technique. The objective is to improve the electrical characterizations of the NiTi/SiO2/Si M.O.S structures. Themorphology evolution of the powder particles, the phase identification and the alloying evolution process as function of milling time were studied using scanning electron microscopy, X-ray diffraction and transmission electron microscopy. In addition, th…

Morphology and structure of electrospun CoFe2O4/multi-wall carbon nanotubes composite nanofibers

2010

CoFe2O4/multiwall carbon nanotubes (MWCNTs) composite nanofibers were produced by electrospinning a dispersion of MWCNTs in a solution of polyvinylpyrrolidone, iron(III) nitrate nonahydrate, cobalt (II) acetate tetrahydrate, absolute ethanol and H2O. Microstructure was examined by scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HR-TEM). Thermal behaviour was studied by thermogravimetry and differential thermal analysis (TG-DTA) and phase analysis of calcined fibers was performed by X-ray diffraction (XRD). Upon thermal treatment at 450 °C defect-free, randomly oriented composite fibers having a mean diameter of 60 ± 10 nm were obtained. The results s…

Synthesis of bulk FeAl nanostructured materials by HVOF spray forming and Spark Plasma Sintering

2006

Abstract This paper examines the efficiency of two consolidation processing techniques: High Velocity Oxy-Fuel (HVOF) spray forming and Spark Plasma Sintering (SPS) to obtain bulk nanostructured materials from an Y 2 O 3 reinforced Fe–40Al (at.%) milled powder. The microstructures of the sintered end-products were characterized by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) in order to gain new insights in their microstructure formation mechanisms. HVOF spray forming is more effective to retain fine nanograins, in particular within retained unmelted powder particles. The drawbacks of this technique are that it inevitably leads to a high fraction of porosity…