Morphology by electron microscopy

Fig. 12 Comparison of fibril morphology by electron microscopy. A -amyloid peptide (Aj8(io-35)) and B A/3(io-35)-PEG-3OOO conjugate. Scale 200 nm. Reprinted with permission from [53]. Copyright 1998 American Chemical Society...

To examine semicrystalline block copolymer morphology by electron microscopy, the specimens need to be sectioned and stained to provide sufficient imaging contrast. Though challenging, the development of new sample-preparation protocols has recently enabled the examination of individual crystals within block copolymer microdomains [Loo et al. 2000b]. Optical microscopy is a long-established technique for investigating crystalline superstructure, especially the presence and structure of spherulites. Recently, atomic force microscopy (AFM) has been applied to study the structures of thin supported films of crystallizable block copolymers. Optical and AFM measurements are nondestructive and can be conducted in or near real time so the process of crystallization can be tracked. 

Thin films of metals, alloys and compounds of a few micrometres diickness, which play an important part in microelectronics, can be prepared by die condensation of atomic species on an inert substrate from a gaseous phase. The source of die atoms is, in die simplest circumstances, a sample of die collision-free evaporated beam originating from an elemental substance, or a number of elementary substances, which is formed in vacuum. The condensing surface is selected and held at a pre-determined temperature, so as to affect die crystallographic form of die condensate. If diis surface is at room teiiiperamre, a polycrystalline film is usually formed. As die temperature of die surface is increased die deposit crystal size increases, and can be made practically monocrystalline at elevated temperatures. The degree of crystallinity which has been achieved can be determined by electron diffraction, while odier properties such as surface morphology and dislocation sttiicmre can be established by electron microscopy. 

A remarkable feature common to both iPP and sPP is that the lamellar morphological units of the mesophase obtained at ca. 0 °C evidenced by electron microscopy [38,39], hardly change in lateral size, thickness, or shape upon annealing and recrystallizing into the stable crystal form at about 80 °C. 

Prerequisite for these observations was the development of proper analytical procedures to visualize the morphology of these blends by electron microscopy.5 7... 

The morphology of AmB lipid complexes was examined by electron microscopy. Two different preparation techniques were used freezefracturing and air-drying. 

P3h1 mice do not die prematurely but have abnormal collagen fibril morphology in tendon, decreased bone density, and abnormalities in skin and developing limbs lethal at El 1.5 basement membrane is not formed well by electron microscopy... 

From an experimental point of view, observations of the initial phase separated morphology via electron microscopy is complicated by the removal of unreacted monomer, except for the fully polymerized stage. 

Complete characterization of poisoned catalysts, of course, requires much more than chemical analysis. For example, the interaction of poisons with catalyst constituents and with each other has been studied by X-ray diffraction and by electron microscopy, the morphology of the poison deposits by optical methods, the distribution within the catalyst pellets and washcoats by the microprobe, and the distribution of poison on the surface of the active metals by Auger spectroscopy. 

As reported previously, the morphology of fibrous cellulose-polyvinyl copolymers, determined by electron microscopy, depends on the method of free-radical initiation of the copolymerization reaction, the experimental conditions during the reaction, and the type of vinyl monomer used. Variations in the shape of the fibrous copolymer cross section, in layering effects in the copolymer structure, and in location and distribution of the polyvinyl polymer within the fibrous structure were shown (1,2,7,29,52). 

Ultrasound constitutes an easily performed activation method, which does not require any expensive or specialized equipment.7,16 In most cases, it is not necessary to pre-activate the metal before addition of the organic coreagents. The changes in morphology and surface composition brought about by sonication were studied by electron microscopy and Auger effect analysis.17... 

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