Alexander Redkin

Fluoride molten salts are the most promising media for molten salt reactors utilizing highly active actinides as the products of the spent nuclear fuel reprocessing. Knowledge of the thermophysical properties of molten mixtures is a crucial key point for the reactor operation. Using an experimental approach and simulation techniques, the heat capacity and thermal conductivity of molten NaF-LaF3 system were studied in the temperature (1100 K ≤ T ≤ 1800 K) and concentration (15–100 mol. % of LaF3) ranges. The experimental setup provided the determination of the molten salt properties up to temperatures of 1200 K at LaF3 concentrations up to 35 mol. %. The molecular dynamics method made it possible to extend this range to temperatures up to 1800 K and LaF3 concentrations up to 100 mol. %. The solidus and liquidus temperatures of the NaF-LaF3 system, as well as the temperature dependences of the isobaric heat capacity and thermal diffusivity, were experimentally determined. In addition, the heat capacity and thermal conductivity of liquid LaF3 were calculated at T = 1800 K. The approximation line slopes of the experimental and calculated data coincide. The discrepancies obtained between the experimental and computational data were 25 % for heat capacity and 15 % for thermal conductivity. The developed model may be used to supplement the experimental data under conditions that are challenging for measuring equipment and to obtain the thermophysical properties of the fluorides of refractory elements.

The thermal diffusivity of LiF-NaF-KF (FLiNaK), NaF-KF and FliNaK-NdF3 mixtures was studied by laser flash method near the melting point. The obtained results demonstrate that the thermal diffusivity of the melts slowly decreases within a certain temperature range. Thermal diffusivity of eutectic FLiNaK and NaF-KF mixtures was found to drop sharply at the temperatures of 30–50 ° below the melting point. These values correspond to the overcooling interval. Thermal conductivity was calculated using the thermal diffusivity heat capacity and density data. Thermal diffusivity of the FliNaK-NdF3 mixture decreases slowly in the phase transition temperature range.

Introduction. Glioblastoma refers to a neuroepithelial malignant brain tumor with an aggressive course and extremely unfavorable prognosis. The median overall survival comprises 14.6 months. Standard treatment demonstrates relatively poor efficiency due to high recurrence rate associated with the high repopulation rate of tumor cells as well as impossibility of eradication of primary tumor. Simultaneous integrated boost is recognized as a technique to enhance local control in gliomas. Materials and methods. The study analyzed data of 25 patients who received chemoradiotherapy for grade 4 glioblastoma in the Radiotherapy Unit No 1. Day hospital lasted from September 2021 to March 2023 (data were analyzed over a year). In group 1, 15 patients received chemoradiation treatment, including simultaneous integrated boost volumetric modulated arc therapy (SIB-VMAT). In group 2, 10 patients received standard fractionated radiation therapy. Results and discussion. Treatment tolerability appeared satisfactory: the target dose was administered in 100% of patients without forced interruptions, toxicity was comparable in both groups; 1-year locoregional control comprised 46.7% in the group with simultaneous integrated boost, 50% in the group of standard fractionated therapy; 1-year overall survival accounted for 66.7% in the group with simultaneous integrated boost, and 70% in the group of standard therapy. The follow-up period revealed no cases of radiation necrosis. The results obtained in the present study appear comparable with the data of relevant scientific publications on the issue. Conclusion. Radiation therapy using simultaneous integrated boost in the postoperative treatment of grade 4 glioblastoma is considered as an acceptable and safe method with moderate toxicity and satisfactory overall survival rate.

The isobaric heat capacity of solid eutectic mixtures LiCl-KCl-CsCl, LiBr-CsBr and LiBr-KBr-CsBr was investigated from room temperature up to melting point. The molar heat capacity of all mixtures under study was found to be close to the additive sum of that of pure salts. The heat accumulated up to melting temperature is directly dependent on the melting point.

Introduction.Glioblastoma is a neuroepithelial malignant brain tumour of predominantly astrocytic origin with an aggressive course and an extremely unfavorable prognosis. Since the median of overall survival with glioblastoma is 14.6 months after complex treatment that includes a combination of surgical treatment, radiation therapy and chemotherapy, the development a personalized approach in the diagnosis and treatment of glioblastomas is appeared to be urgent.Materials and methods. MRIs of a patient undergoing chemoradiotherapy for glioblastoma G4 were performed on the following MRI scanners: Philips Ingenia 1.5T and Philips Ingenia Ambient 1.5T. The analysis of MR-images was carried out using the Matlab 2021 apps.Results and discussion.MR-images were analyzed before and after surgery, and after a course of chemoradiotherapy. The statistical characteristics of the local brightness distribution of the lesion image, which are described by statistical texture parameters, were analyzed as informative features of the lesion area on the images. Initial confirmation of the ability to objectify diagnosis and treatment using the above statistical parameters of T2 MR images of lesion area has been obtained.Conclusion.The aim of further research in this area is to use radiomic study for planning and monitoring the treatment of high-grade gliomas, estimate disease outcomes, and analyze the response to complex treatments in a predictive way.

Although the thermal conductivity of molten salt mixtures is of interest for many potential technological applications, precise values are often hard to obtain. In this study, the thermal diffusivity of FliNaK was studied in a molten state using the laser flash method and found to be very slightly dependent on temperature. The heat capacity of FliNaK was measured using the DSC method. There was a minor difference between our results and data from the literature. From calculations based on thermal diffusivity, density and heat capacity values, thermal conductivity was shown to decrease with temperature.

Skin melanoma is potentially the most dangerous form among all tumor skin lesions. According to statistics, melanoma accounts for about 90% of deaths. The cause of high mortality of patients is early metastasis. At the same time, melanoma metastases can be localized in almost all organs and tissues. In addition to local and regional metastasis to the skin, subcutaneous tissue and lymph nodes, metastatic melanoma of distant organs is not uncommon, and this dramatically worsens the prognosis of the disease. High-quality instrumental diagnostics at various stages of patient management (from primary diagnosis to treatment control) allow to reduce mortality and increase the overall survival of patients. Positron emission tomography in combination with computed tomography (PET/CT) has been used in the last decade as a dominant imaging method for initial staging, control of treatment and detection of progression or recurrence of various types of cancer, including melanoma. It is of great practical importance for predicting survival outcomes, assessing the risk of disease progression, as well as the effectiveness of radiation and systemic therapy. It is PET/CT that allows to simultaneously evaluate the condition of all organs and tissues with minimal radiation load being more sensitive and specific imaging method in comparison with ultrasound, CT and magnetic resonance imaging. PET/CT with 18F-fluorodeoxyglucose is the most effective method for early detection of asymptomatic melanoma recurrence. In addition to accurate setting the tumor process stage, this method is crucial to ensure adequate and effective treatment, which in turn will increase the life expectancy of this category of patients in the near future.

Throughout the world cancer of unknown primary origin occures the 7th place according to morbidity, which is 2.3-5% of all malignant neoplasms and ranks the 4th - according to mortality. In a certain proportion of patients, these metastases are determined independently, without identifying the primary focus. This nosological form of cancer is a heterogeneous disease and usually manifests a pronounced aggressive character in case of progression of the process in the absence of a primary tumor focus. The search for the primary focus and further tactics of treating patients is an embarrassing and under-researched problem that requires numerous studies in future. In addition to standard diagnostic methods, immunohistochemical and virological examinations are used to examine such patients. Most often, patients with metastases in the cervical lymph nodes without a primary identified focus, associated with human papillomavirus (HPV) and Epstein-Barr virus (EBV), which in turn helps to predict the primary localization of cancer. Also diagnostic bilateral tonsillectomy and panendoscopy play the important role. In most cases cancer of unknown primary origin is located in the head and neck. Currently, a search is underway for new diagnostic methods to eliminate delays in treatment and increase the life expectancy of patients. This issue is in demand among researchers around the world. Therefore, further studies are necessary to advance the knowledge of this area.

The LiF–BeF₂ system is used as a heat transfer medium in molten salt reactors (MSRs). The thermal diffusivity of Li₂BeF₄ was studied using the laser flash analysis (LFA) method in solid and transition states. While the thermal diffusivity is shown to decrease slightly in solid-state Li₂BeF₄, it drops significantly at temperatures close to phase transition. The heat capacity of Li₂BeF₄ was measured by differential scanning calorimetry (DSC). Some differences were observed between the results obtained in cooling and heating modes. Thermal conductivity was calculated using thermal diffusivity-, density-, and heat-capacity data. The good thermal conductivity of the Li₂BeF₄ compound in solid and liquid states justifies its use as a heat transfer medium for molten salt reactors.

Introduction. Currently, there are absolute and relative indications for splenectomy in the surgical treatment of gastric cancer.The aim of the study was to improve clinical outcomes of treatment in patients with gastric cancer identifying risks associated with splenectomy, and developing options to correct them. Methods. The study included clinical findings and parameters of the quality of life of 380 patients with gastric cancer who were treated at the Voronezh Regional Clinical Oncological Hospital in 2013-2019. All patients were conventionally divided into 2 groups. The patients of the first group (study group, 172 people) underwent gastrectomy with D2 lymphadenectomy, including splenectomy. The patients of the second group (comparison group, 208 people) underwent spleen-preserving gastrectomy with dissection of lymph node groups 10 and 11. The average follow-up was 39.6 months. In the postoperative period, all patients were examined according to the Clinical Recommendations of the Russian Federation. The SF-36, GSRS questionnaires were used to assess quality of life.Results. Splenectomy increased the incidence of early postoperative complications, including severe complications grades 3 - 5 according to the Clavien-Dindo classification, contributed to the development of reflux esophagitis and, in general, a worsen quality of life in the late postoperative period, but did not affect the patients survival.Conclusion. The data obtained evidence a significantly worse and generally unfavorable safety profile of patients undergoing splenectomy compared to patients who underwent spleen-preserving gastrectomy. Reduced indications for splenectomy appear to be the option to solve this problem. Measures for correction of postoperative complications have been developed for patients with absolute indications for splenectomy.