Imaging dynamic processes

By recording a series of images over the same region of a sample, it is possible to monitor biological processes as a function of time and build up animations of realtime processes. This approach has, for example, enabled the study of processes which include protein fibrillization, the transcription of DNA by RNA polymerase, the translocation of molecules through membrane pores/channels and the enzymatic degradation of potential gene-delivery polymer-DNA complexes. 

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The potendal of the AFM to enhance the characterization of bioerodible polymers, and biomaterials in general, stems from ability of the instrument to obtain veity high resolution images from uncoated polymer. samples within aqueous environments. Therefore, it has become possible to image dynamic processes like surface erosion and protein adsorption which are fundamental to the mechanisms of drug delivery and biocompatibility. 

Third, there are clear differences in the images for dissociation at the same wavelength while probing different spin-orbit states. Two effects contribute to these differences. One is the slight difference in energy in the atomic states, most easily seen in the data at 234 nm where the 0(3P2) data clearly has the strong contribution from vibrationally-excited O2 while the other spin-orbit states do not. In this case the threshold for the dynamical process that forms the vibrationally-excited products has been crossed by the 158.265 cm-1 of the spin-orbit excitation. The second effect is that due to the nature of the J-level. It is known that there is a v—J correlation from the angular fits as well as from the fact that when the polarization of the... 

The past decade saw introduction of the low-energy electron microscope (LEEM) (12). It was expected potentially to be capable of moderately high resolution (6-mn) video-rate imaging of surfaces and interfaces. This would make it capable of studying dynamic processes at surfaces, thin-fibn growth, strain relief, etching, absorption. 

In fact, two-dimensional solid-state NMR is far superior to one-dimensional techniques for studying structure and dynamics123. In particular, the two-dimensional exchange NMR spectrum124 of a static sample is identical with a two-time distribution function125. Thus a two-dimensional NMR spectrum, which is detected for a fixed mixing time, is an image of the state of the dynamic process under study at that time. 

The high temporal resolution of SFM imaging uncovered elementary dynamic processes of structural rearrangements. We observed short-term interfacial undulations [111], fast repetitive transitions between distinct defect configurations [112], their spatio-temporal correlations on a length scale of several microdomains [112], and unexpected defect annihilation pathways via formation of temporal excited states [51, 111]. 

The first atomic-level investigation of the dynamic processes that occur when reduced Ti02 crystals are exposed to oxygen was reported by Onishi and Iwasawa [99]. These authors used a blue crystal with a resistivity of 2 Qm. They acquired STM images while the sample was kept at a temperature of 800... 

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