Largest Principal Axis Research Articles

Gravitational waves by perturbation of a slowly rotating thin-shell wormhole

In this paper, the gravitational wave generation by a slowly rotating thin-shell wormhole is considered. Since the rotating thin-shell wormhole is assumed to be an axisymmetric rigid body, the rotation axis coincides with the largest principal axis which means there is no precession motion. However, if there is a perturbation in the angular velocity, the rotating wormhole can move with precession by perturbation which make arise the gravitational waves. We derive the gravitational wave spectrum, energy loss rate, and angular momentum loss rate.

Synchrotron X-ray and neutron investigation of the structure and thermal expansion of the monoclinic Al13Cr2 phase

The crystal structure of the Al13Cr2 intermetallic phase at 298 K was studied by synchrotron X-ray and neutron diffraction through the analysis of data collected on bulk samples, one in the as-cast condition, one after annealing at 773 K for 24 h and one for 168 h. Furthermore the thermal expansion behaviour of the structure was investigated for the first time in-situ up to 773 K. The diffraction patterns were analysed using whole pattern fitting techniques using the Le Bail and Pawley methods as well as the Rietveld method. The structure was found to be monoclinic with space group C2/m and lattice parameters a = 25.3101 Å, b = 7.6081 Å, c = 10.9689 Å and β = 128.704∘ at 298 K in the as-cast condition. From the temperature variation of the unit cell parameters the principal axes of the thermal expansion tensor were calculated. The largest principal axis has a magnitude of 1.66×10−5 K−1 and lies parallel to b, the second largest lies in the a-c plane at an angle of ∼37° from c in the direction of -a with a value 1.64×10−5 K−1 whereas the smallest lies at ∼53° to c in the direction of +a and has a value of 1.31×10−5 K−1. Analysis of the behaviour of the icosahedra revealed that their expansion is highly anisotropic and the level of anisotropy is related to the point symmetry of the central Cr atoms.

The temperature dependence of nuclear magnetic resonance in a single crystal

The temperature dependence of the nuclear magnetic resonance in a single crystal grown by the slow-evaporation method has been investigated by employing a Bruker FT NMR spectrometer. The three-line structure due to the quadrupole interaction was measured in three mutually perpendicular crystal planes. From the experimental data, the quadrupole coupling constant, , and asymmetry parameter, , are determined at room temperature. The principal axes of the EFG tensor are parallel to the crystallographic a-, b-, and c-axes. The largest principal axis Z is parallel to the crystallographic c-axis. In the temperature range 140 - 400 K, the nuclear quadrupole coupling constant of Li in decreases as the temperature increases. The temperature dependence of the quadrupole parameters is satisfactorily explained with a single torsional frequency of the Li - O ion by means of the simple Bayer theory.

DETERMINATION OF THE ELECTRIC FIELD GRADIENT TENSOR IN MYOGLOBIN-O2AND -CO COMPOUNDS

The EFG tensors at the Fe atoms in myoglobin-02 and -CO are determined by Mzssbauer ex- periments on single crystals. In the MbOz compound the quadrupole interaction (e&Vzz) is negative and the largest principal axis of the EFG lies nearly in the heme plane, while in the MbCO compound eQVzZ is positive and the axis of the EFG is nearly perpendicular to the heme plane. Mzssbauer spectroscopy has provided the most direct knowledge of the iron-oxygen binding in myo- globin (Mb) and hemoglobin (Hb). Although both the 02 and CO compounds of Mb and Hb are diamagnetic, the quadrupole splittings in the 02-form are quite different from those in the CO-form, and the pre- sence of large asymmetric charge transfer is sug- gested in the 02-form /I/. In order to further dis- cuss the bonding structure of ligands to heme iron, not only the principal values of the electric field gradient (EFG) tensor, but also its orientation is strongly required to be determined for these com- pounds. Single crystals were grown from a solution of sperm whale met%, enriched with 57~e, and vi- sually selected perfect crystals were converted into VELOCITY lrnrn/s1 -3 -2 -1 0 1 2 3,-3 -2 -1 0 1 2 3

ChemInform Abstract: THE MICROWAVE SPECTRUM AND QUADRUPOLE COUPLING CONSTANT TENSOR OF BROMOMETHYLSILANE

Chemischer InformationsdienstVolume 4, Issue 50 Organoelement Compounds ChemInform Abstract: THE MICROWAVE SPECTRUM AND QUADRUPOLE COUPLING CONSTANT TENSOR OF BROMOMETHYLSILANE MICHIRO HAYASHI, MICHIRO HAYASHISearch for more papers by this authorKAZUNORI KUWADA, KAZUNORI KUWADASearch for more papers by this author MICHIRO HAYASHI, MICHIRO HAYASHISearch for more papers by this authorKAZUNORI KUWADA, KAZUNORI KUWADASearch for more papers by this author First published: December 11, 1973 https://doi.org/10.1002/chin.197350372AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume4, Issue50December 11, 1973 RelatedInformation

The Microwave Spectrum and Quadrupole Coupling Constant Tensor of Bromomethylsilane

Abstract The microwave spectra of four isotopic species of bromomethylsilane have been measured, viz., the 79Br and 81Br species of BrCH2SiH3 and BrCH2SiD3. The observed rotational constants have been well explained by a model of which the structural parameters have been transferred from the corresponding parameters determined for ethylbromide and chloromethylsilane. The principal quadrupole coupling constants have been determined through the analysis of the first- and second-order effects of quadrupole coupling on the hyperfine structure of the observed spectra. It was concluded, within the experimental error, that the quadrupole coupling constants tensor of this molecule has the cylindrical symmetry around the largest principal axis, the direction of which coincides approximately with the C–Br internuclear line.

Optimization problems in gravitational attraction

Three types of problems in gravitational attraction are considered. In the first type, two isoperimetric ones are solved elementarily by means of a known inequality concerning integral means. In the second one, it is shown that if a homogeneous ellipsoid is divided into two measurable sets, then the gravitational attractive force between them is greatest when the two sets are hemiellipsoids formed by a plane containing the two largest principal axes. In the third one, it is shown that the motion of a free particle in a straight tunnel through a homogeneous ellipsoidal planet is simple harmonic. Furthermore, the periods achieve their maximum and minimum values when the tunnels are parallel to the largest and smallest axes, respectively.