Topic
Gyration tensor
About: Gyration tensor is a research topic. Over the lifetime, 131 publications have been published within this topic receiving 2311 citations.
Papers published on a yearly basis
Papers
TL;DR: In this paper, the atomic positions in a monomeric unit, which were proposed by Hoogsteen, Postema, Pennings, ten Brinke, and Zugenmaier, were validated by using x-ray diffraction experiments.
Abstract: Fibrous and crystal structures of a helical polymer, poly‐L‐lactic acid (PLLA), were analyzed by using x‐ray diffraction experiments. It was confirmed that the molecular residues were arranged on a nonintegral 10/3 helix as De Santis and Kovacs [Biopolymers 6, 299 (1968)] reported. The atomic positions in a monomeric unit, which were proposed by Hoogsteen, Postema, Pennings, ten Brinke, and Zugenmaier [Macromolecules 23, 634 (1990)], were validated. However, the previous reports on the positions of the two helical chains were found to be in error. The correct positions were determined. The second helical chain shifts from the base center by 0.45, 0.25, and 0.61 A along a, b, and c axes. Besides, the second chain rotates by 2.46° with respect to the first. Distribution function of the crystallites in various drawn fibers were determined as a function of spiral angle. Optical gyrations of PLLA and poly‐D‐lactic acid fibers were successfully measured by using high accuracy universal polarimeter, as functions of temperature and drawing ratio. By using x‐ray data of the change of the fibrous structure by drawing treatments, the gyration tensor components of PLLA could be calculated. It is of great interest that gyration tensor component g33 along the helical axis is extremely large, ∼(3.85±0.69)×10−2, which corresponds to a rotatory power of (9.2±1.7)×103°/mm, about two orders of magnitude larger than those of ordinary crystals. This is the first experimental evidence that helical polymers will produce enormous optical activity in the solid state. Helical polymers will be important for the elucidation of gyro‐optical properties of solids and promising for new optical applications utilizing their large optical activity.
314 citations
TL;DR: In this paper, the results of a computer simulation of the evolution of structure in a two component fluid consisting of a liquid phase and a dispersed colloidal phase subjected to a uniaxial field are reported.
Abstract: We report the results of a computer simulation of the evolution of structure in a two component fluid consisting of a liquid phase and a dispersed colloidal phase subjected to a uniaxial field. Our primary objective is to understand the mechanism and kinetics of coarsening and the emergence of crystallinity. Using an efficient, linear-N simulation method we report studies of systems of N=10 000 particles over the concentration range of 10–50 vol %. We present a variety of methods of characterizing the structures that emerge, including the anisotropy of the conductivity, capacitance and dipolar interaction energy, the two-dimensional pair correlation function, principal moments of the gyration tensor, velocity correlation functions, microcrystallinity and coordination number, and the optical attenuation length. We conclude that athermal coarsening is effectively driven by the presence of defect structures and that as the concentration increases, the structures progressively lose the well-known “chain” anis...
138 citations
TL;DR: A new program, MSpin‐RDC, is developed for the analysis of residual dipolar coupling data and analysis of multiconformational problems and fitting of RDC data to relative populations can be accomplished using the single‐tensor approximation.
Abstract: We developed a new program, MSpin-RDC for the analysis of residual dipolar coupling data. This software, specially designed for small molecule analysis, can directly read many molecular-modeling and popular chemistry file formats and accept RDC values as a simple free-format table. Alignment tensor can then be computed by singular value decomposition, as well as predicted using inertia and gyration tensor-based methodologies. Trial structures are then ranked according to their Cornilescu's quality factor (Q) values. Analysis of multiconformational problems and fitting of RDC data to relative populations can be accomplished using the single-tensor approximation.
126 citations
TL;DR: In this article, it was shown that the order of magnitude of this error for a polarizer is about 10−4 and consequently γ lies between 10 −4 and 10−3 in typical optical systems.
Abstract: It was shown in the course of developing the high-accuracy universal polarimeter (HAUP) that any polarimetric optical analyses cannot be free from a systematic error γ originating in the parasitic ellipticities of the constituent Nicol prisms. A method by which one can remove γ in the HAUP method is presented. This has been successfully applied to measurements of the gyration tensors and birefringence of two enantiomorphic crystals of α-quartz. It was found that the order of magnitude of this error for a polarizer is about 10−4 and consequently γ lies between 10−4 and 10−3 in typical optical systems. Our results, g11 = 5.7 ± 0.52 × 10−5 and g33 = −13.6 ± 0.52 × 10−5 with a wavelength of 6328 A for laevorotatory quartz at 300 K are in good agreement with some of the previous reports.
76 citations
4 May 2018
TL;DR: In this paper, the authors introduce tensors as a way of reducing the number of components transformations of axes transformation of a vector transformation of the co-ordinates of a point transformation.
Abstract: Crystals and crystal symmetry - structure of solids close-packing structures two-dimensional lattices three-dimensional lattices crystallographic indices for planes - Miller indices crystallographic direction indices introducing tensors - introduction to the notation reducing the numbers of components transformations of axes transformation of a vector transformation of the co-ordinates of a point transformation and the definition of a tensor second-rank symmetrical tensors - the representation quadric Neumann's principle second-rank tensors - conductivity: thermal conductivity and thermal resistivity heat flow in crystal samples the radius-normal property of the representation quadric electrical conductivity and electrical resistivity diffusion fourth-rank tensors - elasticity strain symmetrical and antisymmetrical tensors the strain tensor stress elasticity the matrix notation effect of crystal symmetry - equating components in cubic crystals and polycrystalline samples elasticity components in other crystal systems crystal optics the indicatrix the wave-surface biaxial crystals double refraction (birefringence) at a boundary definition of an axial tensor transformation of axial vectors transformation of axial tensors optical activity optical activity in the presence of birefringence the gyration tensor - second-rank axial tensor the Hall effect - third rank axial tensor Hall effect - relationship to symmetry magnetresistance and other effects further tensor applications thermal expansion pyroelectric effect piezoelectricity photoelasticity the linear electro-optic effect (the Pockels effect) the quadratic electro-optic effect (the Kerr effect).
66 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2022 | 1 |
| 2021 | 5 |
| 2020 | 4 |
| 2019 | 4 |
| 2018 | 4 |
| 2017 | 2 |