Koch-type wire dipole antennas are considered herein. In the case of a first-order prefractal, such antennas differ from a Koch-type dipole by the position of the central vertex of the dipole arm. Earlier, we investigated the dependence of the base frequency for different antenna scales for an arm in the form of a first-order prefractal. In this paper, dipoles for second-order prefractals are considered. The dependence of the base frequency and the reflection coefficient on the dipole wire length and scale is analyzed. It is shown that it is possible to distinguish a family of antennas operating at a given (identical) base frequency. The same length of a Koch-type curve can be obtained with different coordinates of the central vertex. This allows for obtaining numerous antennas with various scales and geometries of the arm. An algorithm for obtaining small antennas for Wi-Fi applications is proposed. Two antennas were obtained: an antenna with the smallest linear dimensions and a minimum antenna for a given reflection coefficient.

Background: We directly compared the mammography image processing results obtained with the help of the YOLOv4 convolutional neural network (CNN) model versus those obtained with the help of the NCA-based nested contours algorithm model. Method: We used 1080 images to train the YOLOv4, plus 100 images with proven breast cancer (BC) and 100 images with proven absence of BC to test both models. Results: the rates of true-positive, false-positive and false-negative outcomes were 60, 10 and 40, respectively, for YOLOv4, and 93, 63 and 7, respectively, for NCA. The sensitivities for the YOLOv4 and the NCA were comparable to each other for star-like lesions, masses with unclear borders, round- or oval-shaped masses with clear borders and partly visualized masses. On the contrary, the NCA was superior to the YOLOv4 in the case of asymmetric density and of changes invisible on the dense parenchyma background. Radiologists changed their earlier decisions in six cases per 100 for NCA. YOLOv4 outputs did not influence the radiologists’ decisions. Conclusions: in our set, NCA clinically significantly surpasses YOLOv4.

The synthesis of new phenothiazine derivatives, analogs of Methylene Blue, is of particular interest in the design of new drugs, as well as in the development of a new generation of agents for photodynamic therapy. In this study, two new derivatives of phenothiazine, i.e., 3,7-bis(4-aminophenylamino)phenothiazin-5-ium chloride dihydrochloride (PTZ1) and 3,7-bis(4-sulfophenylamino)phenothiazin-5-ium chloride (PTZ2), are synthesized for the first time and characterized by NMR, IR spectroscopy, HRMS and elemental analysis. The interaction of the obtained compounds PTZ1 and PTZ2 with salmon sperm DNA is investigated. It is shown by UV-Vis spectroscopy and DFT calculations that substituents in arylamine fragments play a crucial role in dimer formation and interaction with DNA. In the case of PTZ1, two amine groups promote H-aggregate formation and DNA interactions through groove binding and intercalation. In the case of PTZ2, sulfanilic acid fragments prevent any dimer formation and DNA binding due to electrostatic repulsion. DNA interaction mechanisms are studied and confirmed by UV-vis and fluorescence spectroscopy in comparison with Methylene Blue. The obtained results open significant opportunities for the development of new drugs and photodynamic agents.

The microstrip antennas with symmetrical comb-shaped radiator are considered. The influence of depth of the cuts on main electrical characteristics of four- and eight-comb antennas is researched. The resonance frequency, the bandwidth and reflection coefficient are chosen as characteristics. The graphs of unknown dependencies are constructed for the two basic frequencies.