What's the difference between rhombohedral and tetragonal?

Rhombohedral


Definition:

  • (a.) Related to the rhombohedron; presenting the form of a rhombohedron, or a form derivable from a rhombohedron; relating to a system of forms including the rhombohedron and scalenohedron.

Example Sentences:

  • (1) Crystal structure analysis and refinement at 2.0 A resolution of a rhombohedral crystal form of human annexin V at high calcium concentration revealed a domain motion compared to the previously analysed hexagonal crystal form.
  • (2) Hexagonal rods were compared to rectangular or rhombohedral rods.
  • (3) Assuming the organic template covers the crystal exterior, the projected rhombohedral segment, appearing hexagonal, would seem to contain the protein, hence explaining the apparent presence of the crystal ghost.
  • (4) Furthermore, under conditions known to lead to the formation of rhombohedral crystals of canavalin, a limiting size is reached at high concentrations of canavalin.
  • (5) The inspection of these surfaces using SEM and EDX revealed hexahedrally based crystals including pseudocuboidal, rhombohedral and variable rugged rocky shapes.
  • (6) Detailed analysis of the structure of a single bilaminar lamella shows that each sheet of the two-sheet structure is identical and made up of repeating rhombohedral units whose principal axes are in the ratio of 2:1.
  • (7) The crystals were rhombohedral with an edge length of 0.4 mm.
  • (8) Whereas segments of hexagonal rods in the section should project as octagons at the electron microscope imaging plane, and octagonal profiles are never found, rectangular or rhombohedral rod segments project as hexagons.
  • (9) Precession photographs show that they belong to the rhombohedral space group R3 with unit cell dimensions a = b = 145.4 A, c = 47.5 A, alpha = beta = 90 degrees and gamma = 120 degrees.
  • (10) In naturally desensitized areas on the same dentin surface, most of the dentinal tubules were obturated with rhombohedral crystals of all sizes; membranous structures were not observed in these tubules.
  • (11) The paper describes the arrangement of the atoms within rhombohedral crystals of 2Zn pig insulin as seen in electron density maps calculated from X-ray data extending to 1.5 A (1 A = 10(-10) m = 10(-1) nm) at room temperature and refined to R = 0.153.
  • (12) Rhombohedral crystals grow in 1.8 to 2.0 M ammonium sulfite, pH 7.8 at 21 degrees C, and tetragonal crystals grow in 2.6 M magnesium sulfate, pH 5.5 at 25 degrees C. Analysis of TNF by isoelectric focusing under native and denaturing conditions indicates that TNF molecules exist as trimers in solution.
  • (13) In the presence of 1% phenol, 1.0 M sodium chloride, and at a pH of 8.5, a rhombohedral form is produced with two monomers in the asymmetric unit, space group R3, a = 79.92 A and c = 40.39 A.
  • (14) Mg-containing calcium phosphate crystals including pseudocuboidal, rhombohedral shapes and groupings of quadrangular blades cubically arranged were found in human tooth enamel by scanning electron microscopy and by electron probe microanalysis.
  • (15) The hydrolytic cleavage of the peptide backbone takes place only in preparations containing rhombohedral crystals in addition to free zinc ions.
  • (16) The size measured corresponds to an aggregate of trimers making a unit rhombohedral cell consistent with x-ray crystallographic data (McPherson, A.
  • (17) C43, 1653-1655] is properly described as rhombohedral, space group R3c, with a = 12.355 (4) A, a = 51.01 (2) degrees, Z = 2.
  • (18) Crystals and rhombohedral aggregates of calcite, aggregates of small crystals and tabular crystals of vaterite and fibrous radial aggregates in the form of ooliths were found.
  • (19) Some otoconia are exceptions, evidently seeding and growing in the pure rhombohedral form.
  • (20) The second crystal form is rhombohedral with dimensions unit cell a = 121.1 A, alpha = 60 degrees, space group R32 and diffracts to a resolution of 3.5 A.

Tetragonal


Definition:

  • (a.) Of or pertaining to a tetragon; having four angles or sides; thus, the square, the parallelogram, the rhombus, and the trapezium are tetragonal fingers.
  • (a.) Having four prominent longitudinal angles.
  • (a.) Designating, or belonging to, a certain system of crystallization; dimetric. See Tetragonal system, under Crystallization.

Example Sentences:

  • (1) The crystals are tetragonal, with unit cell dimensions a = 48.9 A and c = 82.0 A, space group P 41 21 2 or P 43212.
  • (2) The morphological unit of the regular array appeared to consist of four spherical subunits, each about 2 nm in diameter, which were arranged in a tetragonal pattern about 4.5 by 7.0 nm in dimension.
  • (3) Two different tetragonal crystal forms have been characterized, both diffracting to about 6 A using synchrotron radiation.
  • (4) The outer structured layer was a linear array of particles overlying an inner tetragonal array of larger subunits.
  • (5) An activity assay of redissolved tetragonal form crystals indicates that the uncleaved, functional serpin has been crystallized.
  • (6) The A ring of the steroid in the tetragonal crystal was found to be disordered, and exists in both a normal and inverted conformation.
  • (7) One was in a hexagonal array, and the other was in a tetragonal array.
  • (8) The crystals are tetragonal rods with unit cell dimensions a = 128.6 A, c = 92.5 A.
  • (9) A hydrated cobalt ion is found to coordinate to two N7 atoms of adjacent guanines, forcing these two guanines to destack with a large dihedral angle (32 degrees), in the dimer of the tetragonal form.
  • (10) These tubules are clearly distinguishable by their shape and fine structure from the periodic structure of a P. rhodos cell wall layer, which exhibits a tetragonal pattern, and also from polyheads and polysheaths of defective bacteriophages.
  • (11) The structure crystallizes in the tetragonal space group P41 with a = 8.225 (5) and c = 28.42 (1) A.
  • (12) This truncated S-protein was exported via the periplasm to the cell surface, but could not self-assemble into a tetragonal array or be anchored to the cell surface.
  • (13) Bacillus sphaericus strain P-1 has previously been shown to have a tetragonally arrayed (T layer) protein which forms the outer layer of the cell wall.
  • (14) Its three-dimensional structure from two different crystal forms (tetragonal and trigonal) has been determined by X-ray diffraction analysis at 1 A resolution.
  • (15) Both crystal forms are tetragonal, the space group for form I is P4(1)22 (or P4(3)22), and that for form II is P4(2)22.
  • (16) Density variations suggest an arrangement of subunits, either tetragonal or trigonal, viewed from a variety of angles about the DNA axis.
  • (17) The binuclear copper site is characterized as two tetragonal Cu(II) atoms bridged by both an endogenous protein ligand and the exogenous ligand (i.e., peroxide), with the lack of an electron paramagnetic resonance signal being the result of antiferromagnetic exchange via the endogenous bridge.
  • (18) The crystals are tetragonal, show the symmetry of space group P4(1) or its enantiomer, have lattice constants of a = 58.46 (1) and c = 77.02 (3) A, and scatter to at least 2 A resolution.
  • (19) These elevations were distributed according to a tetragonal pattern with a periodicity of 850 A.
  • (20) Crystals are tetragonal, with space group P42(1)2, a = b = 171 A, c = 150 A in the absence of ATP; and P422, a = b = 101 A, c = 114.4 A in the presence of ATP.