Search results for "Microscope"

Observation of instability of faceted crystals in lipid monolayers

1998

Abstract The morphological instabilities of two-dimensional hexagonal crystals in lipid monolayers are studied. Fluorescence microscopy indicates that beyond a critical size the faceted crystal develops into dendrites with unusual tip growth behavior, which is not consistent with the current theory of dendritic growth. The morphological transitions in relation to the driving force for two-dimensional crystal growth are also studied.

Study of the MOCVD growth of ZnO on GaAs substrates: Influence of the molar ratio of the precursors on structural and morphological properties

2007

Abstract ZnO thin films were grown by metal-organic chemical vapour deposition (MOCVD) on GaAs(100) and GaAs(111)A substrates. The growth experiments were performed at temperatures ranging from 290 to 500 ∘C and atmospheric pressure. Diethylzinc (DEZn) and tertiary butanol (tBuOH) were used as Zn and O precursors, respectively. The crystallinity of the grown films was studied by X-Ray Diffraction (XRD) and the thickness and morphology were investigated by Scanning Electron Microscopy (SEM). The influence of substrate orientation and molar ratio of the precursors on the crystalline orientation and morphology of the ZnO grown films was analysed.

1988

Structure et proprietes thermodynamiques de polyamides rigides portant ces groupes lateraux flexibles

Detailed study of defects in thin fullerite films

2012

The structural investigations of fullerite films were performed using high-resolution electron microscopy, electron diffraction and electron energy loss spectroscopy and X-ray photoelectron spectroscopy. In particular defects such as dislocations, stacking faults and twins were studied in details. It was shown that fullerite films could be characterized by a face-centered cubic (f.c.c.) structure with lattice parameter a = 1.416 nm. They are distinguished for their rich polytypic structure that is caused by breaking of alteration of closely packed planes of (111) type. The quantitative method based on information theory using the “run-length encoding” algorithm was suggested to evaluate the…

Microstructural evolution of mullites produced from single-phase gels

2007

The crystalline microstructure of mullites obtained by heating monophasic gels has been investigated. Gels with alumina to silica molar ratio of 3:2 (as in secondary mullite) and 2:1 (as in primary mullite) were prepared by gelling mixtures of aluminium nitrate and tetraethylorthosilicate. Phase transformations were induced by heating the gel precursors, with different final treatment temperatures between 1173 and 1873 K. The mullites formed as a result of thermal treatment were studied by means of X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The crystalline structure (unit-cell parameters) and microstructure were determined from X-ray diffraction pa…

Basic Electron Microscopy

2006

Deposition of Cu Nanoparticles on the Surface of Metallic Aluminum

2012

Deposition of Cu particles by electrolysis at constant electrode potential and by internal electrolysis methods was investigated. The composition of deposited material was confirmed by optical and scanning electron microscope methods. Combination of electrolysis at constant electrode potential with internal electrolysis method was found most effective for fabrication of nanoparticle arrays. Single crystalline Cu particles are fabricated by internal electrolysis, while polycrystalline ones obtained by combined chronopotentiometric and internal electrolysis methods. The formation mechanism of Cu nanoparticles is described.

Microchemical surface analysis of historic copper-based coins by the combined use of FIB-FESEM-EDX, OM, FTIR spectroscopy and solid-state electrochem…

2019

[EN] A multi-technique strategy, including microscopy, spectroscopic and electrochemical techniques, is proposed to study thin corrosion layers that form on the surface of historic copper-based coins. An accurate characterisation of this external corrosion layer is important for selecting a suitable conservation and/or restoration treatment. For this purpose, a series of copper-based coins from different historical periods and provenances, which mainly exhibited atmospheric corrosion, was analysed. The morphology of the corrosion layer and the upper core of coins was studied in trenches done on coin surfaces with a focused ion beam gun, coupled to a field emission scanning electron microsco…

Raman spectroscopy characterization of 10-cash productions from the late Chinese emperors to the Republic

2017

[EN] The use of Raman spectroscopy for discriminating monetary emissions, a recurrent problem in much archaeological studies, is described. The method involves the record of Raman signatures of tenorite and crystalline and defective cuprite in the patina based on the idea that subtle, mint-characteristic variations in the composition and metallography of the base metal during the manufacturing process are reflected in the variation in depth of the composition and crystallinity of the corrosion patina. The technique was applied to a series of 10-cash copper coins produced around the transition between the Kuang Hsu and Hsuan Tung last Chinese emperors and the first Republic whose averaged co…

Permeability changes of integrin-containing multivesicular structures triggered by picornavirus entry.

2014

Cellular uptake of clustered α2β1-integrin induces the formation of membrane compartments that subsequently mature into a multivesicular body (MVB). Enhanced internalization mediated by clustered integrins was observed upon infection by the picornavirus echovirus 1 (EVI). We elucidated the structural features of virus-induced MVBs (vMVBs) in comparison to antibody-induced control MVBs (mock infection) by means of high-pressure cryo fixation of cells followed by immuno electron tomography during early entry of the virus. Three-dimensional tomograms revealed a marked increase in the size and complexity of these vMVBs and the intraluminal vesicles (ILVs) at 2 and 3.5 hours post infection (p.i.…