Elliptical Hollow Research Articles

Form-induced birefringence in elliptical hollow photonic crystal fiber with large mode area

We propose a novel type of photonic crystal fiber (PCF), including an elliptical hole in its solid core. We prove the feasibility of such a fiber and investigate both experimentally and theoretically the dependence of its group birefringence on the geometric hole parameters. We show, for the first time, that form-induced birefringence can be achieved in single mode PCFs with large mode area and suggest it as a possible route for the development of polarization maintaining PCF-based LMA fiber devices.

Hepatocyte Organoid Culture in Elliptic Hollow Fibers to Develop a Hybrid Artificial Liver

A novel organoid culture was developed in which hepatocytes maintain high liver functions for more than several weeks in vitro. The main disadvantage of tissue-engineered organoids is the lack of a blood vessel structure between the aggregated cells. Because of depletion of oxygen, the thickness from the surface of an organoid at which hepatocytes can survive is limited. This study showed that a rat hepatocyte organoid that forms by using centrifugal force in a hollow fiber (HF) had a survival limit thickness of about 80 - 100 microm from the surface of the organoid. Based on the value, we designed an elliptic HF having less than 150 microm minor diameter by using a simple annealing method. All hepatocytes were supplied with oxygen and formed an organoid without a dead cell layer in this HF A hepatocyte organoid in an elliptic HF maintained ammonia removal activity twice as high as in the original HF for at least one month during culture. Albumin secretion activity of an organoid in an elliptic HF was also maintained for at least one month and was the same level as that of liver in a living body. In conclusion, organoid culture by using an elliptic HF seems to be a promising technique to develop a hybrid artificial liver.

Control of atomic rotation by elliptical hollow beam carrying zero angular momentum

The interaction between linearly polarized elliptical hollow beam and a two-level atom is investigated theoretically. Although the linearly polarized elliptical hollow beam does not carry angular momentum, it can produce very high torque. The atoms initially at rest and located at off-beam-axis positions will rotate under the drive of the torque of the beam. The shorter the distance from the original location of atom to the axis is, the larger the average angular frequency of atom rotation is. The average angular frequency can reach as high as 1000 Hz. This convinces us that the elliptical hollow beam might be a useful tool in the study of quantum property of Bose–Einstein condensate or ultra cold atom media.

A Closed Contour With No Warping: A Common Feature in all Confocally Elliptical Hollow Sections

We show that for a confocally elliptical hollow section under Saint-Venant’s torsion, there always exists a confocally elliptical closed contour inside the section that exhibits no warping. This property is generally true without any regard to the thickness or the aspect ratio of the hollow section, as long as the inner and the outer ellipses are confocal. This property allows us to apply Packham and Shail’s (Packham, B. A, and Shail, R., 1978, “St. Venant Torsion of Composite Cylinders,” J. Elast., 8, pp. 393–407) superposition method for the torsion solutions of a two-phase elliptical hollow section. Previously, this superposition method is only applicable to symmetric compound sections with respect to a straight line or a circular arc.

Electromagnetic pinning of vortices on different types of defects

We consider the general case of vortex interaction with elliptic hollow cylinder at a distances smaller than the London penetration depth. For the first time, the analytical solution of this problem is obtained, which permits us to treat the case of a vortex near the insulating strip of finite length inside the superconductor. Our results are applicable to superconducting films with regular arrays of defects like elliptic holes (antidots) or segments (antisegments). It turns out that the interaction is basically governed by the largest dimension of the defect. We analyze how the collection of defects weakens the intervortex interaction and makes it anisotropic. The solution of the problem of vortex interaction with a cylindrical hole in anisotropic superconductor is obtained as well. Finally, we demonstrate how the surface defects suppress the field of the vortex entrance. This effect is very important for layered superconductors.

Surface impedance of elliptical hollow conducting waveguides

Currently the literature describes two approaches to the determination of power loss in the hollow metallic elliptical waveguide. The well known perturbation method employing the intrinsic impedance of the metal has frequently been used, and an ?-dependent surface impedance in two different forms has recently been proposed by several workers. In this work it is suggested that sufficient evidence exists to indicate that the ?-dependent formulation is unnecessary.

Electromagnetic Waves in Elliptic Hollow Pipes of Metal

A theoretical study of the transmission of electromagnetic waves in hollow conducting pipes of elliptic cross section, including field configurations, critical frequencies, velocities of propagation, and attenuations for the six lowest order waves. The pipe of circular cross section is treated as a special case, and the stability of waves in it for small deformation of the cross section is discussed.