Fretting definition

We now focus our attention on the presence of the unperturbed donor quantum yield, Qd, in the definition of R60 [Eq. (12.1)]. We have pointed out previously [1, 2] that xd appears both in the numerator and denominator of kt and, therefore, cancels out. In fact, xo is absent from the more fundamental expression representing the essence of the Forster relationship, namely the ratio of the rate of energy transfer, kt, to the radiative rate constant, kf [Eq. (12.3)]. Thus, this quantity can be expressed in the form of a simplified Forster constant we denote as rc. We propose that ro is better suited to FRET measurements based on acceptor ( donor) properties in that it avoids the arbitrary introduction into the definition of Ra of a quantity (i />) that can vary from one position to another in an unknown and indeterminate manner (for example due to changes in refractive index, [3]), and thereby bypasses the requirement for an estimation of E [Eq. (12.1)]. 

Experimentally, FRET interactions are observed and quantified by measuring the donor or acceptor emission signals. The most common and practical definition of FRET efficiency is... 

Although this convenient definition of (R)tw is somewhat different from that employed in the context of SM-FRET [Cf. Eq. (6)], one does not expect this distinction to modify the main observations reported below. 

FYom the multitude of intricate corrosion processes in the presence of mechanical action (friction, erosion, vibration, cavitation, fretting and so on) it is justified to touch upon corrosion types joined under a single failure mode induced by mechanical stresses. These are the stresses that govern the corrosion wear rate of metals during friction. Such processes are usually called corrosion stress-induced cracking in the case that the mechanical action is effective only in one definite direction, or otherwise termed corrosion fatigue in the case that compressive and tensile stresses alternate within cycles. In spite of the differences between the appearance of these corrosion types, they have much in common, e.g. fundamental mechanisms, the causes, and they overlap to a certain degree [19]. 

Fluorescence Resonance Energy Transfer (FRET), Fig. 1 (a) Jablonski diagram illustrating FRET and related processes, including excitation of the donor, radiative (solid line) and non-radiative (dashed lines) relaxation on the donor and acceptor, vibrational relaxation (short curved arrows), and transitions associated with FRET (dotted lines). Processes that determine the FRET efficiency are indicated in bold, (b) Illustration of spectral overlap between Cy3 (donor) emission and Cy5 (acceptor) absorption, (c) Definition of the angles used to calculate... 

Corrosion is the destructive attack of a metal by chemical or electrochemical reaction with its environment. Deterioration by physical causes is not called corrosion, but is described as erosion, galling, or wear. In some instances, chemical attack accompanies physical deterioration, as described by the following terms corrosion-erosion, corrosive wear, or fretting corrosion. Nonmetals are not included in this definition of corrosion. Plastics may swell or crack, wood may split or decay, granite may erode, and Portland cement may leach away, but the term corrosion, in this book, is restricted to chemical attack of metals. 

TR-FRET assays are, by definition, assays applying gated detection. Due to their relatively wide use in drug discovery, practically all plate reader vendors have adapted their instmments to read TR-FRET assays too. Both xenon flash lamps and nitrogen lasers are applied in the plate readers to create short-lived and intense excitation pulses at the area of 330-340 nm. 

One definition of fretting is "Wear phenomena occurring between two contacting surfaces having oscillatory relative motion of small amplitude." Note Fretting is a term frequently used to include fretting corrosion. This usage is not recommended. 

Environment Chemical definition Circumstance Type, chemistry, concentration, phase, conductivity Velocity, thin layer in equilibrium with relative humidity, wetting and drying, heat transfer boiling, wear and fretting, deposits... 

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