Atomic force microscopy regions

Whereas STM is best suited for imaging atoms, atomic force microscopy is more appropriate for larger structures. The following image shows a strand of DNA. The two blue regions of the figure are protein molecules bound to the DNA. 

The thickness of the ordered crystalline regions, termed crystallite or lamellar thickness (Lc), is an important parameter for correlations with thermodynamic and physical properties. Lc and the distribution of lamellar thicknesses can be determined by different experimental methods, including thin-section TEM mentioned earlier, atomic force microscopy, small-angle X-ray scattering and analysis of the LAM in Raman spectroscopy. 

In addition to surface analytical techniques, microscopy, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), scanning tunneling microscopy (STM) and atomic force microscopy (AFM), also provide invaluable information regarding the surface morphology, physico-chemical interaction at the fiber-matrix interface region, surface depth profile and concentration of elements. It is beyond the scope of this book to present details of all these microscopic techniques. 

Regarding the spatial aspects of the enzymatic degradation of CA-g-PLLA, a surface characterization [30] was carried out for melt-molded films by atomic force microscopy (AFM) and attenuated total-reflection Fourier-transform infrared spectroscopy (ATR-FTIR) before and after the hydrolysis test with proteinase K. As exemplified in Fig. 3 for a copolymer of MS = 22, the AFM study showed that hydrolysis for a few weeks caused a transformation of the original smooth surface of the test specimen (Fig. 3a) into a more undulated surface with a number of protuberances of 50-300 nm in height and less than a few micrometers in width (Fig. 3b). The ATR-FTIR measurements proved a selective release of lactyl units in the surface region of the hydrolyzed films, and the absorption intensity data monitored as a function of time was explicable in accordance with the AFM result. 

It is also thought that one of the functions of UvrB is in lesion verification. A region of UvrB, a flexible p-hairpin structure, is inserted into the DNA helix to verify that the distortion represents bona fide DNA damage and to determine which strand contains the damage. Atomic force microscopy has revealed that the DNA is actually wound around the UvrB protein, and it has been suggested that the... 

Scanning tunnelling microscopy, scanning electrochemical microscopy, and AFM-surface potential measurements have also been used to investigate Nafion films. Scanning electrochemical microscopy reveals a domain-like structure containing circular features ca. 1-2 nm in diameter made up of a conductive center (presumed to be ion-rich regions) surrounded by a much less conductive zone. " Atomic force microscopy surface potential measurements detect features that were interpreted as ion channels in Nafion membranes. The size of the claimed ion channels was... 

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