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BACKGROUND: Surgical treatment of breast cancer plays a major role in the combined and complex treatment of patients. The purity of the examined edges of the resected breast tissue is the main indicator of the reliability of the breast-conserving surgery and one of the main factors in the development of local recurrence. Neoadjuvant (preoperative) systemic therapy allows evaluating the effectiveness of therapy in vivo and reducing the size of the initial formation, both in locally advanced and resectable forms of breast cancer. The main advantage of this treatment is the ability for surgeons to perform breast-conserving surgery to improve patients quality of life and aesthetic outcomes without compromising disease-free and overall survival. AIM: To study the clinical and pathological characteristics and analyze of the breast-conserving surgery in patients with breast cancer after neoadjuvant chemotherapy. MATERIALS AND METHODS: 156 performed breast-conserving surgery after neoadjuvant chemotherapy were analyzed. Breast-conserving resection implied radical removal of the residual tumor node within healthy breast tissues with the achievement of negative resection margins. If pathologists detected stained invasive cells/cancer in situ in a formalin-fixed preparation, a second surgical intervention was performed. RESULTS: Of the 156 studied anatomical preparations after breast-conserving surgery, a positive margin was found in 4 (2.56%) cases. In 4 patients, positive margin was represented by ductal carcinoma in situ. According to the results of trephine biopsy, no intraductal component was found before neoadjuvant chemotherapy. The greatest length of the ductal carcinoma in situ section is 2.2 mm. In 3 cases, the distance to the stained resection margin of the micropreparation was 1 mm. As a result of repeated pathomorphological examination of pre-cut margins after surgical intervention, cancer in situ was not found. CONCLUSIONS: The ongoing neoadjuvant systemic therapy for breast cancer with a partial or complete response of the tumor increases the percentage of breast-conserving surgery performed in patients who initially belong to the group of radical mastectomy, but who want to save breast tissue.

Introduction. Differential diagnosis of some pathological processes in the breast is difficult on the background of dense breast tissue. This often leads to false conclusions and to late diagnosis of breast cancer (BC) or unreasonable biopsy in a benign process. 50% of breast cancers detected less than 12 months after elective mammography were associated with high density of breast tissue. An important advantage of contrast enhanced spectral mammography (CESM) is that it does not depend on the size of the lesions and the X-ray density of the breast tissue. Objective. To compare the diagnostic performance of CESM and digital mammography (DM) in detection of breast cancer in a group of women with dense breast tissue.Materials and methods. The data of 438 patients with suspected breast cancer examined from August 2018 to January 2021 were analyzed in the study. The mean age of women was 50 ± 11 years (from 21 to 86 years). In the study group 154 (35%) malignant and 284 (65%) benign lesions were identified. All lesions were histologically verified. Breast tissue density corresponded to types A and B in 161 patients and corresponded to C and D types in 277 patients according to the ACR classification. 154 cases of breast cancer were identified, including 49 patients with density A and B and 105 patients with density C and D types.Results. Sensitivity, specificity and overall accuracy of DM were 85.7%, 87.3%, 86.8%, respectively. Diagnostic performance of CESM significantly higher than of DM with sensitivity, specificity and accuracy of 96.8% (p < 0.001), 93.3% (p = 0.015), 94.5% (p < 0.001), respectively. CESM had high positive and negative predictive values of 88.7% (p = 0.012) and 98.1% (p < 0.001), which exceeded those of DM – 78.6% and 91.9%, respectively. The diagnostic performance of DM and CESM were comparable in women with normal breast density (types A and B according to ACR), but in patients with high breast density (types C and D according to ACR), CESM was significantly more sensitive in detecting breast cancer.Conclusion. Thus, diagnostic efficiency of CESM in detecting breast cancer significantly higher in comparison with digital mammography.

Breast cancer is one of the most common malignant neoplasms among women nowadays. Timely diagnosis is the basis for effective and successful treatment of this disease. The existing classical methods of X-ray examination (MG, ultrasound, MRI) play a major role in the detection of breast cancer, but in some cases, the diagnosis of breast cancer can be difficult. Therefore, diagnostic performance of scintimammography with specialized gamma camera called molecular breast imaging (MBI) is now of particular clinical interest.Materials and methods. 312 patients with a preliminary clinical diagnosis of breast cancer were examined in the department of radionuclide diagnostics of N.N. Petrov Research Center of Oncology. They underwent scintimammography (MBI) with a specialized gamma camera manufactured by GE (Discovery 750b). Images of both breasts were obtained 15 min after intravenous injection of 500 MBq activity of 99mTc-MIBI. The foci of moderate and intensive radiopharmaceutical accumulation in breast were considered as a sign of a tumor. The diagnostic performance of MBI and the sensitivity in detection of various biological subtypes of cancer were calculated by comparing with the results of morphological and immunohistochemically studies.Results. The sensitivity, specificity and accuracy of the MBI in the diagnostics of breast cancer were 88, 75 and 87%, respectively. Sensitivity of this method in detection of different biological subtypes ranged from 89% to 95% with lowest performance found in luminal A subtype.Conclusion. Scintimammography (MBI) is an informative way of breast cancer diagnostics. The revealed differences in the sensitivity of the method in patients with different biological subtypes of breast cancer confirm the need for further study of this topic.

Introduction. The emerging resistance of bacteria to drugs is one of the serious problems of medicine, which stimulates the constant search for new antimicrobial drugs, also of natural origin. Researchers widely address representatives of various families and genus of the plant world, using various morphological groups of plant raw materials, studying the effect of both the sum of extracted substances and individual compounds.Aim. Investigation of antimicrobial activity of water-alcohol extracts of some representatives of the genus Potentilla in the search for new antimicrobial medicines of plant origin.Materials and methods. The objects of the study were extracts on 40 and 70 % ethyl alcohol from the aboveground part of Potentilla anserinа L., P. erecta (L.) Raeusch, P. argentea L., P. paradoxa Nutt. ex Torr. et Gray, P. goldbachii Rupr., P. approximate Bunge, P. chrysantha Trevir. Antimicrobial activity was determined by diffusion into agar using paper disks. Collection strains of Escherichia coli, Pseudomonas aeruginosa, methicillin-sensitive Staphylococcus aureus (MSSA) and 29 strains of MSSA isolated from biomaterial from patients were used as test cultures. The sensitivity of MSSA strains to antibiotics was characterized by an antibioticogram.Results and discussion. The strain of Escherichia coli turned out to be insensitive to all extracts of the paws. The strain of Pseudomonas aeruginosa is minimally sensitive to extracts of 40 % ethyl alcohol of P. anserinа and P. argentea, to 40 and 70 % extracts of P. approximata. All strains of Staphylococcus aureus (MSSA) are sensitive to all extracts of the paws to varying degrees. Among 40 % of the extracts, the most active are P. anserinа, P. paradoxa and P. erecta extracts, among 70 % of the extracts are P. paradoxa and P. argentea extracts.Conclusion. The studied extracts of seven Potentilla species showed antimicrobial activity against both sensitive and insensitive to antibiotic strains of Staphylococcus aureus (MSSA) to a close or comparable degree, while extracts on 40 % ethyl alcohol are slightly more active compared toextracts on 70 % ethyl alcohol. The results indicate that the studied Potentilla species are promising for further research.

Data of echography of 210 verified on the operation and in histological research lipomas, including 182 (86.7 %) encapsulated and 28 (13.3 %) diffuse. Four possible rims along the periphery of the formations have been identified. The morphological nature of these acoustic manifestations and the frequency of their occurrence have been determined. Elastography did not improve its differentiation by showing the boundaries of formations more clearly.

Aim: To perform expert assessment of monitoring data on air pollution and surface water in the Ryazan region, Central Russia. Methods: A descriptive study. The information of state standards and regulations in the field of sanitation and hygiene, local acts in the field of environmental monitoring, a number of federal and regional statistical books were studied, analyzed and systematized. Screening evaluation of the analytical information, identification and generalization of problems in the existing system of chemical monitoring and identification of hazards and risks were done. We used a method for analyzing and synthesizing statistical information and a method of converting absolute values to relative values. The system analysis allowed us to draw conclusions and recommendations and to suggest the directions for further research. Results: The analysis of atmospheric air and surface water pollution information in the Ryazan region is presented. The urgent need to change the existing system for monitoring atmospheric air and surface water is shown. The ways of the environment chemical monitoring effectiveness increasing and increasing the level of objectivity of environmental quality assessment procedures in the Ryazan region are outlined. The necessity of working and organizing a system of continuous operational monitoring of environmental components, monitoring of toxicants and implementation of independent expert monitoring of environment components with the further going aim to develop "Medical and ecological Atlas of Ryazan region". Conclusions: The situation with chemical pollution of the atmosphere and surface water objects in the Ryazan region has been stagnating since the 1990s. Periodic ultra-high pollution parameters were detected, in some cases exceeding the maximum permissible standards by tens and hundreds of times. The solution of the effectiveness and environmental quality assessment reliability problem lies in the improvement of the state monitoring system and the support of independent expert monitoring.

Medicinal leeches (Hirudo verbana Carena, 1820) used in veterinary medicine, human medicine and pharmacology, are currently bred artificially at bio-factories. The technology of leech culture as a component of aquaculture biotechnics is based on the method of accelerated growth of leeches due to intensive feeding, which allows you to get high-quality products in a fairly short time (8-10 months). Nevertheless, the problem of assessing the physiological status of raised individuals upon artificial reproduction remains not fully addressed. The findings we present herein for the first time allow us to suggest that the age-specific amino acid composition of tissues can be used to assess the physiological state and well-being of medicinal leeches in nature and in aquaculture. The aim of the work is to study the age-dependent content of the free amino acids in the tissues of medicinal leeches artificially bred in aquaculture. Studies were conducted in 2012 on the leech (Hirudo verbana Carena, 1820) individuals without signs of diseases which were purchased at the biofactory International Center for Medicinal Leeches (Moscow Province, p. Udelnaya). Leeches were kept in the laboratory in glass vessels with dechlorinated water at 20-22 oC and fed once a month with fresh bovine blood from healthy animals. The experimental specimens of H. verbana was: 5 days (newborn filaments, 0+), 1, 3, 5, 7 and 9 months old, with an average body weight of 0.029, 0.09, 0.25, 0.61, 1.33 and 1.81 g, respectively. Newborn individuals served as a control. The concentration of free amino acids (AA) in the skin and muscle tissue was determined on the analyzer AAA-339M (Mikrotechna, Czech Republic). A total of 105 leech specimens were used, 30 bioassays were prepared, and 660 element determinations were performed. The amino acid composition of the tissues of medicinal leeches H. verbana was represented by 23 AA and their derivatives. The dominant AA with an antioxidant orientation, regardless of age, were glutamine and glutamic acid, alanine, valine, leucine, and glycine, the total content of which was 65 % in filaments, and 58 % in 9-month — old individuals of the total fund AA. In the tissues of medicinal leeches, as well as in warm-blooded animals, the full composition of essential amino acids (EAA) was revealed: threonine, valine, lysine, leucine, isoleucine, histidine, arginine, methionine, phenylalanine, tryptophan. With age, the total concentrations of free amino acids decreased (r = -0.98 at p = 0.000), due to a sharp decrease in the content of arginine (24.0-fold), proline (13.4- fold), isoleucine (12.2- fold), glycine (8.5- fold), lysine (6.8- fold), histidine (6.6-fold), leucine (5.2-fold), ornithine (4.0- fold), glutamic acid and glutamine (3.8-fold), and alanine (2.9-fold). At the age of 5, 7 and 9 months, leeches had a trace content of secondary metabolites: taurine, citrulline and tryptophan (p < 0.001). However, the amino acid balance of nitrogen and protein metabolism was not disturbed, since the ratio of essential / non-essential AА did not change significantly and was 0.60 in newborn filaments, 0.73 — in 9-month-old leeches. It was found that the growth and development of H. verbana was accompanied by a significant decrease in the indicator of maturity (glycine/alanine) from 0.75 (newborn filaments) to 0.25 (9 months). The information available in the literature and the data of our research allow us to put forward the concept of using functional amino acids as biomarkers in the development of the scientific bases of technologies for the industrial breeding of these amphibionts.

Background: Dual-energy contrast-enhanced spectral mammography (CESM) is one of the latest methods for breast lesions characterization, where structural and functional (i.e., vascularization) assessment are combined. Nowadays an interpretation of contrast-enhanced images is based only on the degree of contrast enhancement, but we propose a more detailed assessment of the structure of the hypervascular lesions by highlighting the contrast enhancement patterns. Purpose: To evaluate the diagnostic performance of contrast-enhanced spectral mammography (CESM) using the contrast enhancement patterns in malignant and benign lesions. Material and Methods: Study included 332 women examined from February 2018 to June 2020. The mean age of the women was 50 years. Of 428 lesions totally revealed, 172 (40.2%) were histologically verified as malignant and 256 (59.8%) as benign. We proposed 9 types of contrast enhancement patterns to describe lesions: reticular, granular, annular, diffuse-spherical, lacunar, cloud-like, heterogeneous-annular, point, cotton-like. Results: We showed that diagnostic performance of CESM increased sensitivity if an additional diagnostic feature of contrast enhancement pattern was used: sensitivity increased from 79.7% to 94.8% (p = 0.26), specificity from 82.4% to 95.3% (p = 0.013) and accuracy from 81.3 to 95.1% (p = 0.004), in comparison with using of only one feature of contrast enhancement intensity in the differential diagnosis of malignant and benign lesions. Conclusion: Thus, using contrast enhancement pattern allows to increase the efficiency of CESM in breast cancer detection.

Currently, ecological trails exist in almost all natural protected areas, but not all of them are suitable for disabled people and physically challenged people visiting. The purpose of this article...

The goal of rehabilitation of patients with hearing loss is to increase their rehabilitation potential as a result of medical and pedagogical assistance provided to them. In modern conditions, the relevance of remote medical and pedagogical counseling and support for patients with hearing loss of all ages is increasing. At the moment, we are faced with a new reality, when the availability of number of cares has become limited or unavailable, regardless of the location of the patient. Remote support helps to continue providing medical and educational assistance to people with hearing impairments, to start aiding newly identified patients, to make a wider coverage of children and adults, to help children with complex and multiple developmental disabilities. For the implementation of remote medical and pedagogical support, various means and forms of work are used, implemented via the Internet. In this format, work for children and adults with hearing impairment and after cochlear implantation is conducted by an audiologist and a teacher of the deaf, and the patient’s family is actively involved. The advantages of remote support: greater availability, regular and comfortable patient follow-up, increased efficiency and optimization of dynamics tracking. The remote format of work is a completely new model of behavior for specialists and families of patients with hearing impairment, which requires training and consolidation of new skills for optimal remote medical and pedagogical counseling. The result of the proposed measures is to increase the rehabilitation potential of patients with hearing impairment, improve their hearing and speech skills, and integrate them into the general environment.

We present new data of the comparison of the geographical variability of heavy metal concentrations (Cu, Zn, Mn, Fe, Cd, Pb, Ni) in tissues of medical leeches (Hirudo medicinalis, Hirudo verbana) and in bottom deposit from places of their inhabitation in various regions of Russia and Ukraine. The geographical factor was found to have a significant impact on the elemental status of medical leeches and bottom sediments. It was shown that, irrespective of geographic and biotopic timing, both types of medicinal leeches are macroconcentrator Zn and deconcentrator Mn and Fe. A high cumulative activity of H. medicinalis and H. verbana in relation to ecotoxicants Cd, Pb and Ni in aquatic ecosystems of industrial regions was revealed. A decrease in bioaccumulation activity towards heavy metals in specimens of medical leeches living in adverse climatic conditions on the northern and eastern borders of the range is shown. The ability of leeches H. medicinalis and H. verbana to regulate the level of essential metals Mn and Zn in the body is established, while the content of Cu, Fe, Cd, Pb, Ni is determined by the concentration of these elements in the habitat (bottom sediments). A high variability of the studied parameters and the general laws of bioaccumulation activity of leeches in relation to heavy metals are caused of significant correlation with climatic and geographical features of the studied regions, and a degree of anthropogenically modified territories. It is shown that the microelemental status of leeches as a whole objectively reflects regional specificity of the ecological conditions of hydrobiocoenosises. Thus, the performed investigation can be used in monitoring actions for preservation of water resources and protection of natural biological resources of the hirudofauna.

For the first time, the results of a comparative analysis of free amino acids in the blood plasma of amphibians of the Ural fauna are presented: an endemic species (Siberian salamander (Salamandrella keyserlingii Dybovsky, 1870)) and an invasive species (marsh frog (Pelophylax ridibundus Pallas, 1771)). The species diversity of adaptive strategies of thermoresistant amphibionts both to negative and positive temperatures is shown.

We analyze here for the first time the plasma free amino acid profile in pond bats (Myotis dasycneme Boie, 1825) living in the boreal Ural region and exposed experimentally to low positive and near-zero temperatures during their preparation for hibernation. Pond bats were caught in their mass habitation territory in the Middle Ural near the Smolinsky cave (N 56°28’, E 61°37’) in the third decade of September 2015. Qualitatively, blood plasma in pond bats contains 21 amino acids. In a model experiment carried out on pre-hibernating animals at a regular hibernation temperature (0–2°C), the total plasma pool of free amino acids increased significantly by 42% (irrespective of sex) and reached 1561.4 ± 112.6 μmol/L (p = 0.01). Under these experimental conditions, the fraction of glucogenic amino acids rose by 34% (p = 0.01) and that of essential ones by 80% (p = 0.001). Both in control and experimentally cooled pre-hibernating animals, the plasma was found to lack tryptophan, suggesting its utilization as a substrate in the synthesis of serotonin, a biogenic amine directly involved in the maintenance of hypothermia and hypometabolism in these chiropterans.

The amino acid spectrum of blood plasma in three bat species (Myotis dasycneme, Pipistrellus nathusii, Vespertilio murinus) inhabiting the Urals has been studied for the first time. The bats were trapped in the zone of their high abundance in Chelyabinsk oblast (2013–2014). Free amino acids were determined by liquid ion exchange chromatography (a total of 384 determinations). It has been shown that the plasma amino acid spectrum consists of 22 amino acids in subadult bats of all three species, but there are species-specific differences in their concentrations. The total amino-acid pool concentration in migratory P. nathusii and V. murinus exceeds that in resident M. dasycneme by factors of 2.9 and 1.8, respectively. Migratory species are characterized by a high concentration of plasma arginine: it is six times higher in V. murinus than in M. dasycneme, and in P. nathusii arginine accounts for 25.4% of the amino acid pool. The group of glucogenic amino acids is prevalent in the blood plasma of migratory species (75% in V. murinus and 79% in P. nathusii), while in M. dasycneme the total proportion of lysine, glycine, and glutamic acid is 2.3 times lower than in P. nathusii and 1.7 lower than in V. murinus (p < 0.05). These results provide evidence for significant differences in the contents of free blood plasma amino acids between migratory and resident bat species.

The purpose of this article is to determine the jurisdictional nature of the conclusions of medical and social expert commissions and military medical commissions in disputes over their appeal by state authorities (using the example of the Ministry of Defense of Ukraine). More than 350 decisions of administrative courts of various instances, medical commissions, as well as medical legislation regulating the activities of medical social expert and military medical commissions, and the procedure for conducting medical, social and military medical examinations, became the material for this study. The methodological basis of this work was the method of empirical analysis judicial practice, which allowed autors to identify and analyze court decisions, as well as methods of legal analysis, systematization and synthesis of medical legislation and others. The concept of this article is based on the use of a single methodological approach - positivism. The main result of the work was the scientific substantiation of the administrative-legal nature of the conclusions of the medical-social expert and the military-medical commissions. The article notes that the conclusions of these medical institutions are aimed at ensuring the implementation of state policy in the field of rehabilitation of persons with disabilities, the creation of legal, economic, political, social, social and psychological conditions to meet their needs in restoring health, material support, feasible labor and public activities, by their nature are public in nature and are subject to appeal in administrative proceedings. The legal status of medical-social expert and military-medical commissions in controversial legal relations in understanding the provisions of the administrative procedural law defines these medical institutions as subjects of authority, has been substantiated. The legal disputes between the Ministry of Defense of Ukraine as the central executive body and the military-medical commissions should be resolved out of court, including through measures of state coercion, it is noted.

The results of CFD research using the VOF method with Open Foam open source are presented. In the process of study, we built a digital model allowing us to analyze and predict the process of interaction of the dampening solution with substrate (paper) surface in the measuring cell of the PDA ultrasonic device. Discretization of the area for calculation was created using the blockMesh utility. A block-structural hexahedral computational grid has been constructed. The computational grid area is presented in such a way that the number of cells increases in the direction of the paper sample. The visualization of calculations in the ParaView package coincides with the time intervals obtained on the PDA ultrasonic measuring device. The practical significance of the study lies in the realization of the possibility to evaluate the dampening solution parameters, to control the modes of its supply, taking into account the use of modern papers and printing systems.

The article presents the results of a new comparative analysis of free amino acids in the blood plasma of representatives of insectivorous Chiroptera (Mammalia: Vespertilionidae) in the fauna of the Ural Mountains: the pond bat (Myotis dasycneme Boie, 1825) and the parti-colored bat (Vespertilio murinus Linnaeus, 1758). This is the first study to show the species variability of free amino acids in resident and migratory species of bats from different ecosystems of the Ural Region.

Ecological features and species composition of leeches were studied in 25 water bodies located in the city of Yekaterinburg and its vicinity. Specific features of their occurrence and distribution in water bodies of various types were analyzed. Dominant, mass, common, and rare species were distinguished.

The study included data on 168 patients with breast cancer, surgical treatment of whom was supplemented by axillary dissection (133 patients or 79.2%) or biopsy of sentinel lymph nodes (35 patients or 20.8%). The examination included ultrasound, planar scintigraphy of the breast and zones of regional lymph drainage. In 122 patients with primary breast cancer stage cT1-2N0M0 retrospective analysis of radionuclide imaging sentinel lymph node was performed. In 89 patients the introduction of colloidal radiopharmaceutical was carried out using a particle diameter of not more than 80-100 nm, in 33 patients study was conducted after administration of radiocolloid with a particle diameter of 200 to 1000 nm. Based on the data obtained by scintigraphy and ultrasonography of zones of regional lymph drainage there were offered two diagnostics models: the first, in which the presence of metastatic axillary lymph nodes was established when there were changes according to at least one of the diagnostic methods--scintigraphy or ultrasound; the second, in which the defeat of lymph nodes was determined only in the case of simultaneous detection of ultrasound and scintigraphic evidence of axillary lymph nodes. Sensitivity, specificity, and overall accuracy of the combination of ultrasound and planar scintigraphy axillary lymph nodes using the first model accounted for 82.7%, 67.7% and 74.4%, respectively. In the second model, the specificity was 94.6%, sensitivity--56%. Rapid transport of radiopharmaceuticals from the injection site, a high gradient of radiopharmaceuticals accumulation in sentinel lymph nodes, effective their visualization, approaching to 100%, were undoubted advantages of radiocolloids having a particle diameter up to 100 nm.

The purpose of this study was to establish the role of scintimammography with 99mTs-technetril for predicting pathological status of regional lymph nodes after neoadjuvant chemotherapy. In 123 primary patients with locally advanced breast cancer stage cT1-4N0-3M0 there was performed scintimammography: before treatment and after 2-3 cycles of neoadjuvant chemotherapy 63 patients; after 2-3 cycles of neoadjuvant chemotherapy and before surgery--in 5 patients; after 4-6 cycles of neoadjuvant chemotherapy--55 women. All patients were divided into 2 groups: the first included 68 patients whom scintimammography was performed before and after 2-3 cycles of neoadjuvant chemotherapy; the second--60 women whom scintimammography was performed before treatment and before surgery. In patients of the first group positive results were obtained in 16 (23.5%), negative--26 (38.3%), false positive--16 (23.5%) and false negative--10 (14.7%) cases. Sensitivity, specificity, overall accuracy, positive predictive value and negative results were 61.5%, 61.9%, 61.7%, 50% and 72.2%, respectively. During the scintimammography after 4-6 cycles of neoadjuvant chemotherapy positive results were observed in 17 (28.3%) negative--18 (30%), false positive--19 (31.7%) and false negative--6 (10%) of patients. Thus, the sensitivity, specificity, overall accuracy, positive predictive value and negative results amounted to 73.9%, 48.6%, 58.3%, 47.2%, 75% respectively.

The crystal structure of anhydrous K4V2O7 (I) is determined by powder X-ray diffraction. The compound crystallizes in the monoclinic system (a = 10.222(1) A, b = 6.2309(8) A, c = 7.282(1) A, β = 101.31(1)°, space group C2/m, Z = 2). The structure contains layers of isolated V2O7 pyrovanadate groups separated by layers of potassium cations. The hydration and dehydration of I are studied by thermal analysis and high-temperature X-ray diffraction. The dehydration is accompanied by decomposition of the starting crystal hydrate to give intermediate compounds. Anhydrous compound I undergoes a reversible phase transition at 740°C. The high-temperature phase is assumed to have a hexagonal unit cell (a = 6.169(4) A, c = 15.72(1) A, Z = 2).

The first tin vanadium phosphate SnVPO5 was synthesized by a solid-state reaction and characterized by X-ray single crystal diffraction and magnetic susceptibility measurements. The crystal structure of SnVPO5 ( a = 5.2633 ( 4 ) A , b = 6.5252 ( 9 ) A , c = 6.8785 ( 10 ) A , α = 113.283 ( 11 ) ° , β = 108.037 ( 9 ) ° , γ = 94.603 ( 9 ) ° , S.G. P-1, Z = 2 ) is a three-dimensional framework constructed by V2O10 units fasten together by tetrahedral phosphate groups. Tin atoms are situated in structure interstices. They have five-fold coordination arrangement due to a presence of sterically active lone pair which position was visualized by ELF calculations. The magnetic susceptibility shows a broad maximum at 22 K which is probably due to low-dimensional spin correlations. We propose that the magnetism of the compound can be understood by interacting spin-dimers on a distorted square lattice. Strong quantum fluctuations were suggested by unusual field dependence of the transition temperature and unexpectedly low Curie constant.