String-like domains

Thus observation of ferroelectric domain reversal induced by indirect electron beam irradiation in LiNb03 bulk crystals represents a pronounced fdb effect. The reversed structure represents domain clusters consisting of multiple string-like domains with nanometer radius and 350 pm lengths. Fabricated one- and two-dimensional domain configurations could be used for a broad range of new 2-D as well as potential 3-D nonlinear photonic devices. 

In Table 10.2 below we summarize the calculated values of the shape invariant r 2//m and aspect ratio rm/lm of string-like domains in different fe crystals formed under the fdb conditions. The experimental parameters used for these calculations are U = 3kV (applied voltage), R = 50 nm (typical radius of curvature of the tip apex), d = 0.5 nm (distance between the tip apex and the sample surface). The calculated aspect ratios rm/lm are quite different for the chosen fe. 

Under the electron microscope titin appears as a flexible beaded string 4 nm in diameter. Most of the molecule is made up of repetitive domains of two types. In human cardiac titin there are 132 folded domains that resemble type III fibronectin repeats and 112 immunoglobulin-like domains.98 In a "PEVK region," between residues 163 and 2174, 70% of the residues are Pro, Glu, Val, or Lys. The titin molecule may be organized as polyproline helices in this elastic region.1023 At the C terminus of titin 800 residues, including a Ser / Thr protein kinase domain, are found within the M-line. 

The results summarized in this review represent the early stages of an ongoing research effort at 3M, which in effect is a three-dimensional approach to surface chemistry , i.e. an area of science between surface chemistry and solution chemistry. The sorption sites on the polymer are not representable as an immobile surface between solid and liquid domains, but rather are string-like polymer molecules undulating in a sea of liquid, so that the adsorption phenomenon must be represented three-dimensionally on a molecular scale rather than two dimensionally. 

Titin is a very long string of immunoglobulin-like (Ig) and fibronectin-like (Fn3) domains with some intervening unique sequences such as the... 

Some polypeptide chains fold into two or more compact regions that may be connected by a flexible segment of polypeptide chain, rather like pearls on a string. These compact globular units, called domains, range in size from about 30 to 400 amino acid residues. For example, the extracellular part of CD4, the cell-surface protein on certain cells of the immune system to which the human immunodeficiency virus (HIV) attaches itself, comprises four similar domains of approximately 100 amino acids each (Figure 3.47). Often, proteins are found to have domains in common even if their overall tertiary structures are different. 

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