Knot tie-down

Tie-down of goods on open trucks is a widespread use for a variety of ropes. The requirements are moderate strength, flexibility, low stretch, good knot retention, moderate abrasion resistance, and UV resistance. 

Synthetic, bioabsorbable sutures available today are listed in Table 8.9, together with their chemical structure. As can be seen, they are composed of copolymers, except for PGA and poly-p-dioxanone. One of the monomers in the copolymers of aU sutures is glycolide. The surface of most multifilament sutures is coated to permit easy tissue passage, precise knot placement, and smooth tie-down. The coating materials applied include calcium stearate, poly(E-caprolactone) (PCL), PGLA (30 70), and poly(CL-co-GA). The characteristics of these bioabsorbable sutures are briefly described below. 

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... 

A piece of rope or two long boot laces are needed for this tie. Make the prisoner lie down. Tie his hands behind his back, using any conventional knot. 

Tie tightly, hold it down at the join and tie a knot. Now ail you have to do is carefully hold the hypo at the tube s end just beyond the cutter and pull the rubber band over the plunger 80 it rests across the clipped edges. 

During application, a specific knotting technique is required to handle and tie the sutures. With multifilament sutures, the nature of the material and the braided or twisted construction provide a high coefficient of friction and the knots remain as they are laid down. In monofilament sutures the coefficient of friction is relatively low, resulting in a greater tendency for the knot to loosen after it has been tied. In addition, monofilament synthetic polymeric materials possess the property of memory, with a... 

Drape the scarf around the back of your neck and allow both ends to hang down in the front, one equally as long as the other. Cross the ends over themselves, and tie them together to create one parallel knot. Repeat this three to five times, until you have a braided necktie effect. 

KNOT THE WIRE. Slide the harp base (if used) and socket cap base over the new wire. Cut between the wires to separate about 3" of the end of the two-threaded wire. Strip about Vi" of insulation from each end. Because you don t want the weight of the wire pulling down against the connections, tie a knot in the wires that will be supported by the socket cap—this is called an underwriter s knot. Make a loop in each wire and then pass the end of each opposite strand through each loop. You should end with a high-profile knot that won t pull through the base of the socket cap. 

---