Structure peculiarities of cementite and their influence on the magnetic characteristics

The iron carbide $Fe_3C$ is studied by the first-principle density functional theory. It is shown that the crystal structure with the carbon disposition in a prismatic environment has the lowest total energy and the highest energy of magnetic anisotropy as compared to the structure with carbon in an octahedron environment. This fact explains the behavior of the coercive force upon annealing of the plastically deformed samples. The appearance of carbon atoms in the octahedron environment can be revealed by Mossbauer experiment.Comment: 10 pages, 3 figures, 3 tables. submitted to Phys.Rev.

Pulmonary Vascular Thrombosis in COVID-19: Clinical and Morphological Parallels

Aim. We aimed to study the histological and thrombotic changes in lung vessels in patients who died with COVID-19, to access the correlation between anticoagulation therapy (ACT) and thrombotic events (TE), treatment results, clinical and laboratory patients' characteristics.Material and Methods. We retrospectively analyzed treatment results of patients hospitalized with COVID-19 and lung vessel samples of the deceased patients. Dynamic changes and highest levels of D-dimer and fibrinogen were studied in its correlation with the disease severity according to SOFA score, computer tomographic (CT) results, lung, renal and hepatic dysfunction. The association between different doses of ACT and treatment results, laboratory indicators and thrombotic events was accessed. The histological lung vessels examination was performed using Martius Scarlet Blue (MSB)staining.Results. 313 patients were included in the study (61 patients died). The median age of hospitalized patients was 60 years (IQR 51-66 years). The frequency of the intravitallyconfirmed TE was 4,8%. The strong statistical association was revealed between D-dimer level and 3-4 points SOFA score, patients' mortality, oxygen support requirement, CT3-CT4 pneumonia, glomerular filtration rate and TE. There was no mortality in patients with D-dimer normal references, but in cases with three times elevation reached 13%, 48,5% - in cases with 3-6 times elevation and 64,6% - in cases with more than 6 times elevation. The strong statistical association was registered between fibrinogen and SOFA score, CT 3-4 pneumonia, patients' mortality. D-dimer and fibrinogen levels demonstrated weak correlation. There was no statistical correlation between prophylactic, intermediate and therapeutic ACT and D-dimer and fibrinogen levels, CT results, patients' mortality. MSBstaining was used in 36 deceased patients tissue samples. 1394 lung vessels were analyzed. Lung vessels thrombi persisted in samples of all 36 patients (100%). Vessels with the diameter 3,5-30 mm were thrombosed in 7%, with the diameter 0,034-0,84 mm - in 48%, with the diameter 0,85-3,4 mm - in 45%. The frequency of thrombi persisted 06 hours, 6-12 hours, 12-18hours, 18-24 hours and more than 24 hours was12%, 14%, 62%, 5% and 7% respectively.Conclusion. Thrombi of different ages from fresh to organized were observed in one third of lung vessels in all deceased patients. Lung vessels thrombosis plays an important role in pathogenesis and thanatogenesis of COVID-19. The D-dimer level correlates with lung, renal dysfunction, patients' mortality and doesn't show any correlation with ACT and can be accepted as a criterion of lung vessel thrombotic progression

The Current Status of Direct Oral Anticoagulants in Cancer-Related Venous Thromboembolism Treatment

This article is a review of epidemiology, pathogenesis and treatment of venous thromboembolism (VTE) in cancer patients. In accordance with actual guidelines, the duration of anticoagulant therapy of cancer-related venous thrombosis should be at least 6 months. The use of vitamin K antagonists (VKA) is associated with an increased risk of VTE recurrence and bleeding, so low molecular weight heparin (LMWH), in particular dalteparin, has been the "gold standard" until recently. Compared to VKA, prolonged use of LMWH can reduce the incidence of VTE recurrence without affecting the risk of bleeding or death. The main disadvantage of LMWH is low compliance, leading to premature discontinuation of treatment or switching to alternative anticoagulants. Direct oral anticoagulants (DOACs) have changed the situation. Compared to VKA, they demonstrated higher efficacy with a similar (or improved for individual DOACs) safety in patients with cancer-related VTE. Recently, the results of studies comparing the use of DOACs with dalteparin in cancer patients have been published: SELECT-D (rivaroxaban), HOKUSAI-VTE Cancer (edoxaban), ADAM VTE (apixaban), CARAVAGGIO (apixaban). Rivaroxaban showed higher efficacy than dalteparin with a similar risk of major bleeding, but an increased risk of clinically relevant non-major (CRNM) bleeding. Edoxaban had the same efficacy as dalteparin but increased risk of major but not CRNM bleeding. Apixaban showed similar efficacy and safety as dalteparin in the CARAVAGGIO study, but did not provide higher safety in the ADAM VTE study. It was noted that gastrointestinal and urogenital bleeding dominated in the structure of hemorrhagic complications of DOACs. The results of published trials are reflected in the current guidelines of the specialized societies. DOACs (particularly, rivaroxaban and edoxaban) are recommended for the VTE treatment in cancer patients

Treatment and Secondary Prevention of Venous Thromboembolism in Real Clinical Practice Based on Health Care Professional Survey

Aim. To assess the duration of the anticoagulant treatment of venous thromboembolism (VTE) in various categories of patients in real clinical practice through survey of practitioners, as well as correspondence of the duration with current clinical guidelines.Material and methods. Data obtained from electronic survey of practicing surgeons as part of a commercial brand assessment (Brand Adoption Monitor) was studied. Survey was carried out by the "Validata” analytical agency at the request and with the financial support of Bayer. Inpatient and outpatient vascular surgeons, as well as general outpatient surgeons were invited to complete the electronic questionnaire. The number of interviewed specialists was 100: 50 inpatient vascular surgeons and 50 outpatient specialists, among whom the share of vascular surgeons (phlebologists, angi-ologists) was about 20%. The study was completed in 20 cities of Russia with a population of at least 200,000 people from all federal districts except the North Caucasus and the Republic of Crimea. The selection criteria for participants were: work experience in the specialty ≥3 years, work experience at the current organization >6 months, ≥5 patients with VTE during in the last month.Results. In total, 104 doctors were surveyed during the period from December 11, 2019 to January 20, 2020, of which 50 were inpatient vascular surgeons and 54 were from outpatient setting. According to the survey of vascular surgeons in hospitals, 75% (6 [5;10]) of patients were hospitalized with a primary episode of VTE and 25% (2 [1;4]) with a recurrent thrombotic event. In an outpatient surgeon, 27.5% (3 [2;5]) of patients were treated in an outpatient setting without hospitalization, 34.7% (3 [2;5]) came to an appointment immediately after discharge from the hospital and 38.8% (2 [1;4]) were a repeat visit regarding a previous VTE. Most often, surgeons observed episodes of clinically unprovoked VTE in 27.3% of cases, thrombotic events provoked by major transient risk factors were 12.2%, event provoked by small transient risk factors were 13.3% and events provoked by small persistent risk factors were 12.6%, while cancer-associated thrombosis represented 13.5%. Most surgeons chose to prescribe anticoagulant therapy beyond 3 months. About half of the specialists prescribed therapy for a year or longer for cancer-associated thrombosis and recurrent VTE. When treating the first episode of clinically unprovoked VTE, about half of the respondents chose anticoagulation for a period of 3 to 6 months. About 60% of specialists prescribed anticoagulant therapy for a period of 3 to 6 months to patients with minor transient or persistent risk factors and patients with VTE provoked by major transient risk factor (trauma or surgery).Conclusion. Correspondence of the duration of anticoagulant therapy in real clinical practice with the international clinical guidelines varies within 450% range and, on average, does not exceed 30%. This discrepancy was both in situations when the duration of therapy was lower than recommended, but also in situations when treatment extension would not have been recommended