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The work is devoted to the study and development of a non-toxic and non-hygroscopic system of AgBr - AgI crystals. Crystals of this system are non-toxic, non-hygroscopic, flexible, safe for organic tissues and media, which makes them promising for use in medical technologies. During the development of crystals, the phase diagram of this system was refined. On the basis of the phase diagram, the modes of high-purity raw materials' synthesis and single crystals growth are selected. Using the selected modes, single crystals of various compositions were grown and their optical properties were determined, such as the spectral transmission range and refractive indices at the short-wavelength absorption edge and at the wavelength of the CO 2 laser (10.6 µm), The work results are the basis for the technology development for the production of optical products (infrared fibers, lenses, windows, prisms) for use in laser, endoscopic and diagnostic medicine, including in systems for early diagnosis of cancer.

Infrared photonic-crystal fibers (IR PCF) based on AgClxBr l-x and AgBrxIl-x crystals have been developed for operation at a CO 2 laser wavelength (10.6 µm). The prospects of using fiber optics, including those with a photonic structure, in medical technologies as a conductor of laser radiation are considered. The advantages and disadvantages of unjacket and two-layer fibers, as well as the versatility and uniqueness of photonic crystal fibers are shown. The process of designing optical fibers with a photonic structure is presented, from the stages of mathematical and computer modeling to seven-stage extrusion and properties study. In computer simulations, plane wave and finite element methods were used to analyze the band structure and mode analysis, respectively. In the properties' study, a CO 2 laser and a Spiricon Pyrocam III camera were used. The model was verified with a real fiber by measuring the radiation distribution in the far zone. High convergence of simulation results with the fabricated fiber is obtained. Thus, infrared fibers with an increased mode field diameter were obtained, which are flexible, easy to sterilize and safe for humans for medical applications.

The article discusses infrared polycrystalline fibers based on the AgCl-AgBr crystals system, which are promising for use in medicine, since they are non-hygroscopic, non-toxic, and easy to sterilize. Mid-Infrared radiation (MIR) is interesting for medical applications, since numerous organic molecules and compounds are absorbed in the wavelength range from 2.0 to 15.0 $\mu$ m. To date, various sources of MIR radiation have been developed, such as IR lasers and IR spectrometers. These devices require fiber optic channels to output an optical signal to provide a non-invasive and safe examination of biological tissues and organic substances. Fibers made on the basis of AgCl-AgBr crystals can be used as such channels, since they have a wide transparency range from 2.0 to 20.0 $\mu$ m without absorption windows, have high mechanical strength and flexibility, and low optical loss. Uncladded and cladded polycrystalline infrared fibers are convenient for use in IR spectroscopy for the study of biological tissues. Photonic crystal fibers are convenient for use as fiber radiation leads, since they provide a small aperture and high transmission power of radiation.

A particular political and social mindset toward mental health support has impacted how and why people seek counseling and therapy in Ukraine. Although a relatively small and developing field, art therapy is beginning to provide a means for assisting cultural and identity development for young adult Ukrainians during a time of civil and political unrest. Cross culturally, art therapy has been found to assist young people in developing a healthy self-concept by providing them with a realistic and less defensive view of themselves and their environment. This paper evaluates the development of art therapy in Ukraine, and examines the practice of art therapy with undergraduate Ukrainian students. First, it details findings from a questionnaire with university students to determine their perception of art therapy. Analysis of these findings resulted in identifying their level of satisfaction toward art therapy, and common reasons why art therapy was sought. Second, the article provides a brief vignette to demonstrate how art therapy was used with undergraduate university students to assist with processing negative memories associated with living under the Soviet era. Finally, the article concludes with a discussion about how to tailor art therapy so that instead of being perceived as a cure it promotes self-care, thereby helping overcome the stigma associated with seeking therapeutic services.

This article examines the transmission spectra of crystals based on the AgCl − AgBr, AgBr − TlI, AgBr − TlBr0.46I0.54 (KRS-5), AgBr − AgI systems in the visible, infrared, and terahertz ranges. We've determined the optical characteristics in the terahertz range for polycrystalline plates obtained by hot embossing based on silver and thallium halides' solid solutions. As a study result, silver and thallium (I) halides have demonstrated competitive transmission characteristics both in the visible and infrared spectra also in the THz frequency range. The transmission range for crystals of the AgCl − AgBr system was 0.45–30.0 μm (9.9–666.2 THz) and 250–6000 μm (0.05–1.19 THz) with optical transparency reaching 78%, for crystals of the AgBr − AgI, AgBr − TlI, AgBr − TlBr0.46I0.54 systems, 47.0–60.0 μm (4.9–6.3 THz) and 250–6000 μm (0.05–1.19 THz) with optical transparency reaching 76%. At the same time, in the long-wavelength infrared region from 800 to 6000 μm (0.05–0.37 THz) the absorption coefficient’ value hasn't exceeded 0.1 cm−1 for the AgCl − AgBr crystal system, also lied within 0.1–0.005 cm−1 for the AgBr − AgI, AgBr − TlI, AgBr − TlBr0.46I0.54 crystals systems.

This article presents a fiber-optic channel for delivering infrared (IR) radiation within the range from 2.5 to 25.0 μm. It comprises AgBr – TlBr0.46I0.54 uncladded fibers with an extremely small diameter of 90 μm. In the framework of this study, the infrared crystals of AgBr – TlBr0.46I0.54 system and optical fibers based on them, as well as their properties, are described. The stages of the fiber bundle development are also described: the mathematical evaluation of crosstalk is carried out; the computer simulation of the mode field distribution across the bundle is performed. Based on the numerical results, the geometric parameters of the bundle, enabling the efficient transmission of IR radiation, were selected. The fiber bundle with low crosstalk and high spatial resolution was manufactured.