Knot holding force

Effect of number of throws on the knot holding force in the dry loop tests of Mersilene (M) and silk (S) sutures of sizes 1-0 to 4-0. ... 

Effect of the number of throws on knot holding force in the dry straight tests of three polyester sutures of size 2-0, all braided but finished differently. 

Material Power (W) Energy (J) A B Strength (Kgf) C Knot holding force (Kgf) D E Percent change F... 

The radiation pressure exerted by light is very weak. A bright laser beam of several milliwatts of power can exert only a few piconewtons (pN) of force. However, a force of 10 pN is enough to pull a cell of E. coli through water ten times faster than it can swim.213 In about 1986, it was found that a laser beam focused down to a spot of - one K ( 1 pm for an infrared laser) can trap and hold in its focus a retractile bead of 1 pm diameter. This "optical tweezers" has become an important experimental tool with many uses.213 214 For example, see Fig. 19-19. Not only are optical tweezers of utility in studying biological motors but also mechanical properties of all sorts of macromolecules can be examined. For example, DNA can be stretched and its extensibility measured.215 Actin filaments have even been tied into knots 216... 

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