Barrel alignment

Myers, J. A. and Puhalla, M., Barrel Alignment A Critical Factor in Reducing Extruder Wear, SPEANTEC Tech. Papers, 51, 323 (2005)... 

Barrel alignment It is the alignment at installation and routine maintenance checks to ensure the screw, mold, and any auxiliary equipment attached to the barrel are all aligned. 

Figure 4.2 A p-a-p motif is a right-handed structure. Two such motifs can be joined into a four-stranded parallel p sheet in two different ways. They can be aligned with the a helices either on the same side of the p sheet (a) or on opposite sides (b). In case (a) the last p strand of motif I (red) is adjacent to the first p strand of motif 2 (blue), giving the strand order 1 2 3 4. The motifs are aligned in this way in barrel structures (see Figure 4.1a) and in the horseshoe fold (see Figure 4.11). In case (b) the first p strands of both motifs are adjacent, giving the strand order 4 3 12. Open twisted sheets (see Figure 4.1b) contain at least one motif alignment of this kind. In both cases the motifs ate joined by an ct helix (green).

Figure S.S Amino acid sequence of p strands 2 3 4 in human plasma retinol-binding protein. The sequences are listed in such a way that residues which point into the barrel are aligned. These hydrophobic residues are arrowed and colored green. The remaining residues are exposed to the solvent.

Spherical bearings are usually furnished in a doublerow mounting that is inherently self-aligning. Both rows of rollers have a common spherical outer raceway. The rollers are barrel-shaped with one end smaller to provide a small thrust to keep the rollers in contact with the center guide flange. 

Twin-screw extruders that contain two internal rotating screws that press material against heated barrel walls and forces the resulting molten mass through a restriction die which aligns the mass in the direction of... 

Afonin S, Durr UHN, Wadhwani P, Salgado J, Ulrich AS (2008) Solid state NMR structure analysis of the antimicrobial peptide gramicidin S in lipid membranes concentration-depen-dent re-alignment and self-assembly as a beta-barrel. Top Curr Chem 273 139-154... 

Concentration-Dependent Re-alignment and Self-Assembly as a -Barrel... 

Fig. 8 Proposed model for gramicidin S in a membrane according to the orientational constraints obtained from and N-NMR. The upright backbone alignment (r 80°) and slant of the /3-sheets (p -45°) are compatible with the formation of an oligomeric /3-barrel that is stabilized by hydrogen bonds (dotted lines). A The oligomer is depicted sideways from within the lipid bilayer interior (showing only backbone atoms for clarity, but with hydrophobic side chains added to one of the monomers). Atomic coordinates of GS were taken from a monomeric structure [4], and the two DMPC lipid molecules are drawn to scale (from a molecular dynamics simulation coordinate file). The bilayer cross-section is coloured yellow in its hydrophobic core, red in the amphiphilic regions, and light blue near the aqueous surface. B Illustrates a top view of the putative pore, although the number of monomers remains speculative...

Inspection of the barrel and screw for wear can provide information on the root cause for the wear. For example, if wear occurs at an axial location on only one side of the barrei and on all sides (angular direction) of the screw, then the likely root cause is that the barrel is out of alignment at that axial location. Conversely, if the barrei is worn on all sides and the screw is worn on only one side at the same axial location, then the root cause is likely a local bend in the screw. 

Figure 10.4 Diagram for the operation of barrel supports. The barrel slides on the supports during thermal expansion, allowing the barrel axis to maintain its elevation. If the barrel support does not allow the barrel to slide, then the discharge end of the barrel is forced down and possibly out of alignment...

The location of the copper with respect to the Greek key fold is interesting when compared to that of the cupredoxins. While the copper in the cupredoxins lies in the interior of the /8 barrel bound by three interior-facing residues of the carboxy-terminal loop in the )8 barrel, and by a histidine in an adjacent strand, the copper in SOD lies on the outside of its jS barrel, bound by one residue from the carhoxy-terminal loop and three from the adjacent strand (cf. Figs. 2c-5c with Fig. 8c.) A structural comparison of plastocyanin and SOD, coupled with sequence alignment of plastocyanin and ceruloplasmin (Ryden, 1988), showed that three of the SOD ligands correspond to putative copper ligands in ceruloplasmin. Why this is so will become more evident after the description of the ascorbate oxidase structure and its relationship to ceruloplasmin. 

Bearing bracket alignment. In contrast to horizontally split compressors where the bearing brackets are normally an integral part of the lower case half in barrel machines bearing brackets are bolted to... 

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