The study of a homogeneous column of argon plasma at a pressure of 0.5 torr, generated by means of the Beenakker’s cavity

A homogeneous column of argon plasma at a pressure of 0.5 torr, generated by means of the Beenakker cavity, has been investigated by methods of emission spectroscopy, photography and self-consistent 3D modeling in a nonlocal approximation. It is shown that the plasma column, which spreads beyond the resonator, is spatially uniform and it represents the afterglow of the microwave discharge produced inside the cavity. The simulation data of the spatial distributions of the electron energy density and concentrations of electrons, ions and argon atoms in metastable and radiating states are presented. The results of calculations are in agreement with experimental data

Reconstruction of Moderately and Severely Atrophic Scalp—A Multicentric Experience in Surgical Treatment of Patients Irradiated for Tinea Capitis in Childhood and Surgical Algorithm

Background and Objectives: Before the introduction of griseofluvin, the use of X-ray radiation was the treatment of choice for tinea capitis. More than half a century later various types of tumors have been found to be associated with childhood irradiation due to tinea capitis, most commonly cancers of the head and neck, as well as brain tumors. The often unusually aggressive and recurrent nature of these tumors necessitates the need for repeated surgeries, while the atrophic skin with an impaired vascular supply due to radiation often poses an additional challenge for defect reconstruction. We present our experience in the surgical treatment of such patients. Materials and Methods: This is a retrospective cohort study. In this study, 37 patients treated for acquired defects of the scalp with a history of irradiation therapy due to tinea capitis in childhood were included in this study, 24 male and 13 female patients. The mean age at the first appointment was 60.6 ± 7.8, with the youngest included patient being 46 and the oldest being 75 years old. Patients’ characteristics, surgical treatment, and complications were analyzed and a reconstructive algorithm was developed. Results: Local flaps were used for reconstruction in 34 patients, direct sutures were used in 10 patients and 20 patients received split-thickness skin grafts for coverage of both primary and secondary defects for reconstruction of flap donor sites. One regional flap and one dermal substitute covered by an autologous skin graft were also used for reconstruction. Complications occurred in 43.2% of patients and were significantly associated with the presence of comorbidities (p = 0.001), aseptic bone necrosis (p = 0.001), as well as skin atrophy in frontal, occipital, and parietal region (p = 0.001, p = 0.042 and p = 0.001, respectively). A significant correlation between major complications and moderate skin atrophy was found only in the parietal region (p = 0.026). Conclusions: Unfortunately, many protocols developed for scalp reconstruction are not applicable in the setting of severe or diffuse scalp skin atrophy associated with high tumor recurrence rate and radiation-induced vascular impairment, such as in tinea capitis patients in Serbia. An algorithm has been developed based on the authors’ experience in managing these patients