Screw anchors

Stryker Biosteon , Biozip (interference screw, anchor)... 

Screw anchors (Figure 4.4) transfer tension loads via the interlock of the screw threads with matching female threads cut into the concrete by the hardened forward threads. They are often used for light and medium-duty applications where speed and ease of installation are a factor. The high hardness required for cutting the threads into the concrete makes screw anchors susceptible to hydrogen embrittlement and stress corrosion, particularly under the head, and caution should be exercised where they are used in unprotected environments. Depending on the depth of the threads, screw anchors may have superior tension resistance relative to other expansion anchor types in cracked concrete conditions. 

Threaded Fasteners (Bolt Assembly/Screw Assembly/Stud/Set Screw) Anchor Bolt Threaded Inserts... 

Figure 7.20 shows some of the impellers which are frequently used. Propellers, turbines, paddles, anchors, helical ribbons and screws are usually mounted on a central vertical shaft in a cylindrical tank, and they are selected for a particular duty largely on the basis of liquid viscosity. By and large, it is necessary to move from a propeller to a turbine and then, in order, to a paddle, to an anchor and then to a helical ribbon and finally to a screw as the viscosity of the fluids to be mixed increases. In so doing the speed of agitation or rotation decreases. 

Figure 7,20. Commonly used impellers (a) Three-bladed propeller ( >) Six-bladed disc turbine (Rushton turbine) (c) Simple paddle (d) Anchor impeller (e) Helical ribbon (/) Helical screw with draft tubs...

Anchors, helical ribbons and screws, are generally used for high viscosity liquids. The anchor and ribbon are arranged with a close clearance at the vessel wall, whereas the helical screw has a smaller diameter and is often used inside a draft tube to promote fluid motion throughout the vessel. Helical ribbons or interrupted ribbons are often used in horizontally mounted cylindrical vessels. 

The tightness of the two parts was assured by an indium gasket, and the vacuum chamber was immersed in liquid helium. A small volume (about 1 cm3) of helium gas was inserted into the vacuum chamber for the thermalization at 4.2 K of all the parts of the experiment. The exchange gas was successively pumped out, and the pressure during the measurements was kept below 10 5 torr to reduce any contribution from convection. Each end of the sample strip was tightened between two copper blocks (C, D of Fig. 11.3) by means of brass screws one copper block was anchored to the Cu top (A) and the other (the hot end ) held the heater (FI) and the thermometer (TH). 

Agitators with a large blade area which rotate at low speeds. These include anchors, paddles and helical screws. 

Vertical leveling screws spaced for stability shall be provided on the outside perimeter of the baseplate. They shall be located adjacent to anchor bolts to minimize distortion during the process of installation. These screws shall be numerous enough to carry the weight of the baseplate, pump, and drive train components without excessive deflection, but in no case shall fewer than six screws be provided. 

L.4.5 The baseplate should be located in the desired position by snpporting it on shims or leveling screws and seeming it with anchor bolts. Approximately 25-50 mm (1-2 in.) of gronting clearance should be allowed between the bottom of the baseplate lim and the top of the scarified fonndation. 

The right-handed a-helix (ur) is one of the most common secondary structures. In this conformation, the peptide chain is wound like a screw. Each turn of the screw (the screw axis in shown in orange) covers approximately 3.6 amino acid residues. The pitch of the screw (i. e., the smallest distance between two equivalent points) is 0.54 nm. a-Helices are stabilized by almost linear hydrogen bonds between the NH and CO groups of residues, which are four positions apart from each another in the sequence (indicated by red dots see p. 6). In longer helices, most amino acid residues thus enter into two H bonds. Apolar or amphipathic a-helices with five to seven turns often serve to anchor proteins in biological membranes transmembrane helices see p. 214). 

Slip the spacing sleeves over the feet and screw down the anchor screws tightly. Place the templet on the feet and fasten it with the cap nuts. 

Put the foundation plate in its place and make certain that it lies steadily. Check that the anchor screws do not press against the edges of the holes in the plate, as they would otherwise prevent the resilient mounting of the plate between the rubber cushions. 

With the machine are delivered height adjusting washers to be used for levelling if required. The washers should be placed between the welded-on cap of the anchor screw and the anchoring foot. 

Rubber cushion, large Anchoring screw Height adjusting washer Spacing sleeve Anchoring foot... 

These include anchors, paddles, and helical screws. 

Fig. 23. Some mixers for viscous liquids, (a) Six-blade turbine (b) three inclined-blade paddles (c) helical screw (d) helical ribbon (e) propeller in draught tube (f) anchor. (Reprinted with permission from Chemical Engineering Science, 37, 813, C. J. Hoogendoorn and A. P. Den Hartog, 1967 Pergamon Press pic).

Fig. 18.11. The infinite flip-flop chain in /1-cyclodextrin-11H20 is composed of water molecule Wl and hydroxyl groups 0(3)7 and 0(2)6 which belong to the same yff-cyclodextrin molecule (see also Fig. 18.12). The operation of a 2, screw axis produces the infinite chain which is also anchored in the crystal lattice by many hydrogen bonds to and from adjacent hydroxyl groups (not shown) [454]...

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