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The pitch of a helix is the height of one complete helix turn, measured parallel to the axis of the helix. A double helix consists of two (typically congruent) helices with the same axis, differing by a translation along the axis. [3] A circular helix (i.e. one with constant radius) has constant band curvature and constant torsion. The slope of ...
Helix angle – Helix angle is an angle between the cutting edge and the long access of a file. Helix angle plays an important role in debris collection and it also determines the direction of rotation. Helix angle can be constant or accelerating (changes along the length of a file). Accelerating helix angles decreases the screw in effect when ...
The Macromolecular Crystallographic Information File (mmCIF) also known as PDBx/mmCIF is a standard text file format for representing macromolecular structure data, developed by the International Union of Crystallography (IUCr) and the Protein Data Bank [1] It is an extension of the Crystallographic Information File (CIF), specifically for macromolecular data, such as proteins and nucleic ...
The efficiency can be plotted versus the helix angle for a constant friction, as shown in the adjacent diagram. The maximum efficiency is a helix angle between 40 and 45 degrees, however a reasonable efficiency is achieved above 15°. Due to difficulties in forming the thread, helix angle greater than 30° are rarely used.
Miscellaneous endodontic instruments. From left: Lentulo spiral, reamer, K-file and H-file. Hand files can provide tactile sensation when cleaning or shaping root canals. This allows the dentist to feel changes in resistance or angulation, which can help determine curvature, calcification and/or changes in anatomy, which two dimensional radiographs may not always identif
In physics, a characteristic length is an important dimension that defines the scale of a physical system. Often, such a length is used as an input to a formula in order to predict some characteristics of the system, and it is usually required by the construction of a dimensionless quantity, in the general framework of dimensional analysis and in particular applications such as fluid mechanics.
In statistical mechanics, the Zimm–Bragg model is a helix-coil transition model that describes helix-coil transitions of macromolecules, usually polymer chains. Most models provide a reasonable approximation of the fractional helicity of a given polypeptide; the Zimm–Bragg model differs by incorporating the ease of propagation (self-replication) with respect to nucleation.
The beta strands are parallel, and the helix is also almost parallel to the strands. This structure can be seen in almost all proteins with parallel strands. The loops connecting the beta strands and alpha helix can vary in length and often binds ligands. Beta-alpha-beta helices can be either left-handed or right-handed.