Unwinding force

Release coatings are important components of pressure sensitive adhesive (PSA) products such as tapes and labels [1]. Release materials are coated onto the backside of PSA tape backings (often called low adhesion backsizes or LABs in this form) to provide the desired tape roll unwind force. They are also coated onto various substrates to form release liners for PSA products such as labels and transfer tapes. Typically the thickness of the release coating is less than 1 p,m, and often times less than 0.1 jLm. Release coatings can be thought of as the PSA delivery system, providing a controlled unwind or release force and protecting the adhesive from contamination and unintentional contact until it is applied. 

Pressure-sensitive tapes consist of a carrier, coated, with adhesive on one side, and wound into a roll. The back side is often coated with a release agent to control the unwind force. 

Release coatings are important components of pressure sensitive tapes as they enable the formulator to adjust the release force according to the application, for example, the unwinding force of tapes and the transfer of double-sided tapes to substrates. 

Figure 12.16), can insert between the stacked base pairs of DNA. The bases are forced apart to accommodate these so-called intercalating agents, causing an unwinding of the helix to a more ladderlike structure. The deoxyribose-phosphate backbone is almost fully extended as successive base pairs are displaced 0.7 nm from one another, and the rotational angle about the helix axis between adjacent base pairs is reduced from 36° to 10°. 

The full loop does not produce a force in opposition to the expanding pipe work as in some other types but with steam pressure inside the loop, there is a slight tendency to unwind, which puts an additional stress on the flanges. 

As reaction proceeds, the polymer chain (which is in random coil form) unwinds as the charge on it grows as a result of neutralization and ionization. This contributes to thickening of the cement paste. Cations released become bound to the polymer chain. Countercations can either be bound to a polyanionic chain by general electrostatic forces or be site-bound at specific centres. More than one type of site binding is possible. Complex formation and, if the ligand is bidentate, chelate formation enhance the effect. 

Fig. 5. Monte-Carlo simulation of the stretching of a chromatin chain. A 100 nucleosome chain with 200 bp repeat and 11 bp linker DNA was first equilibrated and then exposed to a pulling force as indicated below the drawings. For displaying the full chain, the scale of the picture was changed with increasing force. An unwinding of the chromatin fiber and sliding of the nucleosomes can be readily observed.

Johnson, Daniel S., Lu Bai, Benjamin Y. Smith, Smita S. Patel, and Michelle D. Wang. Single-Molecule Studies Reveal Dynamics of DNA Unwinding by the Ring-Shaped T7 ffelicase. Cell 129 (2007) 1,299-1,309. By using a laser beam, the experimenters made precise measurements of the movement of the bead, observing the forces imposed by helicase enzymes. 

The wet end—where in an unwind stand the reel of paper is supported and fed under suitable tension controls into a bath of resin at controlled temperature. In many cases, instead of total immersion, the paper is wetted on one side only—to allow the resin to penetrate, force air out, and give a fully saturated sheet. To allow time enough for the required penetration a skying system of variable rollers is used, as shown in Figure 55 this transports the web upwards and then down again before a final immersion in the resin, followed by metering. 

An alternative pathway (Fig. 5.1 Lower) involves the unwinding of the C-terminal half of the a-helix, which then loops back so as to be nearly parallel to the remaining helix. This proximity allows for the possibility of side-chain interactions between the helix and the C-terminal half of the molecule, including hydrophobic interactions between F52 in the helix and either W43 or Y45. This pathway is very similar to the one previously identified by us on the basis of the analysis of the potential of mean force for the G-peptide along two principle component degrees of freedom [144], In both pathways, it is clear that formation of native /3-hairpin contacts can occur without the complete loss of helical secondary structure, making the idea of the a-helix as an on-path intermediate in the formation of the /3-hairpin physically plausible [100],... 

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