Multifunctional THz Graphene Antenna with 360∘ Continuous ϕ-Steering and θ-Control of Beam.

A novel graphene antenna composed of a graphene dipole and four auxiliary graphene sheets oriented at 90∘ to each other is proposed and analyzed. The sheets play the role of reflectors. A detailed group-theoretical analysis of symmetry properties of the discussed antennas has been completed. Through electric field control of the chemical potentials of the graphene elements, the antenna can provide a quasi-omnidirectional diagram, a one- or two-directional beam regime, dynamic control of the beam width and, due to the vertical orientation of the dipole with respect to the base substrate, a 360∘ beam steering in the azimuth plane. An additional graphene layer on the base permits control of the radiation pattern in the θ-direction. Radiation patterns in different working states of the antenna are considered using symmetry arguments. We discuss the antenna parameters such as input reflection coefficient, total efficiency, front-to-back ratio, and gain. An equivalent circuit of the antenna is suggested. The proposed antenna operates at frequencies between 1.75 THz and 2.03 THz. Depending on the active regime defined by the chemical potentials set on the antenna graphene elements, the maximum gain varies from 0.86 to 1.63.

Successful ovarian autotransplant with no vascular reanastomosis in rats.

Preservation of ovarian functions in woman with premature ovarian failure remains an issue in reproductive medicine. Hormone replacement therapy for maintaining endocrine functions, and cryopreservation of embryos or oocytes for those who wish pregnancy, are some of the choices. However, ovarian transplantation is a more physiological alternative, although problems related to ovarian ischemia have been reported. Herein, we investigated the viability of autologous transplantation of the ovarian tissue into the rat peritoneum, without vascular reanastomosis. Twenty animals in the study group had both ovaries excised, and each ovary was dissected into two halves. A half of an ovary was autotransplanted to the peritoneal surface, closely located to the left epigastric vessels. This simple procedure does not require surgical vascular reanastomosis while it maintains appropriate follicular growth and therefore should be further considered as an alternative for women undergoing oophorectomy, not only to maintain endocrine functions but also for fertility preservation.