A simple design of an ultrathin six-band polarization-insensitive terahertz perfect metamaterial absorber (PMMA), composed of a metal cross-cave patch resonator (CCPR) placed over a ground plane, was proposed and investigated numerically. The numerical simulation results demonstrate that the average absorption peaks are up to 95% at six resonance frequencies. Owing to the ultra-narrow band resonance absorption of the structure, the designed PMMA also exhibits a higher Q factor (>65). In addition, the absorption properties can be kept stable for both normal incident transverse magnetic (TM) and transverse electric (TE) waves. The physical mechanism behind the observed high-level absorption is illustrated by the electric and power loss density distributions. The perfect absorption originates mainly from the higher-order multipolar plasmon resonance of the structure, which differs sharply from most previous studies of PMMAs. Furthermore, the resonance absorption properties of the PMMA can be modified and adjusted easily by varying the geometric parameters of the unit cell.
We present a simple design for a broadband tunable terahertz (THz) metamaterial absorber (MMA) consisting of a complementary cross-oval-shaped graphene (CCOSG) structure and dielectric substrate placed on a continuous metal film. Both numerical simulation and theoretical calculation results indicate that the absorbance is greater than 80% from 1.2 to 1.8 THz, and the corresponding relative bandwidth is up to 40%. Simulated electric field and power loss density distributions reveal that the broadband absorption mainly originates from the excitation of continuous surface plasmon resonance (SPR) on the CCOSG. In addition, the MMA is polarization-insensitive for both transverse-electric (TE) and transverse-magnetic (TM) modes due to the geometry rotational symmetry of the unit-cell structure. Furthermore, the broadband absorption properties of the designed MMA can be effectively tunable by varying the geometric parameters of the unit-cell and chemical potential of graphene. Our results may find promising applications in sensing, detecting, and optoelectronic-related devices.
A novel chiral metasurface (CMS) based on T-shaped resonators is proposed and investigated numerically. The CMS is composed of a periodic array of bi-layered conjugated fourfold T-shaped structure. The retrieved effective electromagnetic (EM) parameters indicate that the multi-band negative refractive index associated with strong optical activity and circular dichroism (CD) effect is realized in terahertz (THz) region. The physical mechanism is illustrated by analyzing the current density distributions. Due to its exotic chiral optical properties, the proposed CMS is useful for the development of THz devices.
World widely, Breast cancer is the most common type of cancer amongst women. External and internal factors both are responsible for beginning, advancement and development of breast cancer and from many studies it is well known that environmental elements have a significant effect in etiology of breast cancer. When it comes to environmental factors, effects of viruses are of great concern. Virus-associated cancer brings up a cancer in which the malicious conversion of the host's diseased cells results due to any viral infection. Until now it has learned that human papillomaviruses (HPV), Epstein-Barr (EBV) and mouse mammary tumor virus (MMTV) are the prime candidate viruses that act as agents of causing breast cancer. The initiator is only one in a sequence of steps essential for malignant cells development. Breast cancer could be a hereditary disease but it is expected to account for a very small percentage of breast cancer cases. From this idea it is obvious that there should be more efforts required in evaluating the role of viruses in carcinogenesis that could be characterized by further confounding and synergistic special effects of carcinogenic aspects still exact role of viruses in tumorigenesis is unclear, but it seem like that these are responsible for causing the disease.
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