The redox transformations and nucleophilic replacements as possible metabolic reactions of the drug “Triazaverin”. The chemical modeling of the metabolic processes

As a model of metabolic transformations of antiviral drug “Triazaverin” and its analogues‑2-alkylthio‑6-nitro‑1,2,4-triazolo[5,1-c][1,2,4]triazine‑7-ones 1a-d examined the oxidation of alkylthio groups to the corresponding sulfoxides 2a-d and sulfones 3a-d, as well as the process of nucleophilic substitution sulfonyloxy group of cysteine and cysteamine with the formation of compounds 5 and 6

Role of direct exchange and Dzyaloshinskii-Moriya interactions in magnetic properties of graphene derivatives: C2_2F and C2_2H

According to the Lieb's theorem the ferromagnetic interaction in graphene-based materials with bipartite lattice is a result of disbalance between the number of sites available for $p_z$ electrons in different sublattices. Here, we report on another mechanism of the ferromagnetism in functionalized graphene that is the direct exchange interaction between spin orbitals. By the example of the single-side semihydrogenated (C$_2$H) and semifluorinated (C$_2$F) graphene we show that such a coupling can partially or even fully compensate antiferromagnetic character of indirect exchange interactions reported earlier [Phys. Rev. B {\bf 88}, 081405(R) (2013)]. As a result, C$_2$H is found to be a two-dimensional material with the isotropic ferromagnetic interaction and negligibly small magnetic anisotropy, which prevents the formation of the long-range magnetic order at finite temperature in accordance with the Mermin-Wagner theorem. This gives a rare example of a system where direct exchange interactions play a crucial role in determining a magnetic structure. In turn, C$_2$F is found to be at the threshold of the antiferromagnetic-ferromagnetic instability, which in combination with the Dzyaloshinskii-Moriya interaction can lead to a skyrmion state.Comment: 10 page

Half-metallicity and efficient spin injection in AlN/GaN:Cr (0001) heterostructure

First-principles investigations of the structural, electronic and magnetic properties of Cr-doped AlN/GaN (0001) heterostructures reveal that Cr segregates into the GaN region, that these interfaces retain their important half-metallic character and thus yield efficient (100 %) spin polarized injection from a ferromagnetic GaN:Cr electrode through an AlN tunnel barrier - whose height and width can be controlled by adjusting the Al concentration in the graded bandgap engineered Al(1-x)Ga(x)N (0001) layers.Comment: submitted for publicatio

Canted Ferromagnetism in Double Exchange Model with on-site Coulomb Repulsion

The double exchange model with on-site Coulomb repulsion is considered. Schwinger-bosons representation of the localized spins is used and two spin-singlet Fermion operators are introduced. In terms of the new Fermi fields the on-site Hund's interaction is in a diagonal form and the true magnons of the system are identified. The singlet fermions can be understood as electrons dressed by a cloud of repeatedly emitted and reabsorbed magnons. Rewritten in terms of Schwinger-bosons and spin-singlet fermions the theory is U(1) gauge invariant. We show that spontaneous breakdown of the gauge symmetry leads to \emph{\textbf{canted ferromagnetism with on-site spins of localized and delocalized electrons misaligned}}. On-site canted phase emerges in double exchange model when Coulomb repulsion is large enough. The quantum phase transition between ferromagnetism and canted phase is studied varying the Coulomb repulsion for different values of parameters in the theory such as Hund's coupling and chemical potential.Comment: 8 pages, 6 figure

Outpatient management of patients with peripheral artery disease by cardiologists or surgeons: influence on the prognosis and prevalence of surgical interventions

Highlights. The study shows for the first time that during the three-year follow-up of patients with diseases of the arteries of the lower extremities in the observation groups of a general surgeon and a cardiologist, adverse events (myocardial infarction, stroke, amputation, disability) and deaths occurred more often in a surgeon than a cardiologist. The study proves the correctness and real benefit of such an approach with the involvement of a cardiologist to the outpatient stage of management of a complex cohort of patients with atherosclerosis of the vessels of the lower extremities.Aim. To study the effect the outpatient observation of patients with peripheral arteries disease (PAD) by cardiologists and surgeons has on timing and prevalence of reconstructive surgery and the prognosis of patients. Methods We analyzed the data on 585 PAD patients who underwent outpatient observation from 2010 to 2017, dividing them into 2 groups. The first group (131 patients) managed by an surgeon; the second (454 patients) managed by a cardiologist. Since the groups were not comparable in terms of the initial parameters, the comparability of patients in the groups (observation by a surgeon or by a cardiologist) was achieved using pseudorandomization. The follow-up period was three years; we assessed the incidence of deaths, adverse events, and the prevalence of reconstructive operations.Results. During a three-year follow-up the 1st group, compared with the 2nd, had more deaths in general (p<0.001), death from cardiac causes (p = 0.045), from stroke (p><0.001), as well as the total number of adverse events (p><0.001) and disability (p = 0.065). Indications for reconstructive surgery on the lower extremities arteries (LEA), and operations frequency were comparatible in groups. Amputation history, taking diuretics, presence of rhythm disturbances, and management by a surgeon increased the risk of adverse outcomes. Management by a cardiologist, reconstructive LEA surgeries, female sex improved the prognosis of patients. Conclusion Observation of PAD patients by a cardiologist contributes to a higher frequency of optimal drug therapy by patients and can reduce the number of adverse events in patients and improve their survival without affecting the timing and frequency of reconstructive LEA surgeries. Keywords Peripheral atherosclerosis • Outpatient follow-up • Optimal drug therapy • Reconstructive surgery>˂ 0.001), death from cardiac causes (p = 0.045), from stroke (p˂ 0.001), as well as the total number of adverse events (p˂ 0.001) and disability (p = 0.065). Indications for reconstructive surgery on the lower extremities arteries (LEA), and operations frequency were comparatible in groups. Amputation history, taking diuretics, presence of rhythm disturbances, and management by a surgeon increased the risk of adverse outcomes. Management by a cardiologist, reconstructive LEA surgeries, female sex improved the prognosis of patients.Conclusion. Observation of PAD patients by a cardiologist contributes to a higher frequency of optimal drug therapy by patients and can reduce the number of adverse events in patients and improve their survival without affecting the timing and frequency of reconstructive LEA surgeries.Highlights. The study shows for the first time that during the three-year follow-up of patients with diseases of the arteries of the lower extremities in the observation groups of a general surgeon and a cardiologist, adverse events (myocardial infarction, stroke, amputation, disability) and deaths occurred more often in a surgeon than a cardiologist. The study proves the correctness and real benefit of such an approach with the involvement of a cardiologist to the outpatient stage of management of a complex cohort of patients with atherosclerosis of the vessels of the lower extremities.Aim. To study the effect the outpatient observation of patients with peripheral arteries disease (PAD) by cardiologists and surgeons has on timing and prevalence of reconstructive surgery and the prognosis of patients. Methods We analyzed the data on 585 PAD patients who underwent outpatient observation from 2010 to 2017, dividing them into 2 groups. The first group (131 patients) managed by an surgeon; the second (454 patients) managed by a cardiologist. Since the groups were not comparable in terms of the initial parameters, the comparability of patients in the groups (observation by a surgeon or by a cardiologist) was achieved using pseudorandomization. The follow-up period was three years; we assessed the incidence of deaths, adverse events, and the prevalence of reconstructive operations.Results. During a three-year follow-up the 1st group, compared with the 2nd, had more deaths in general (p<0.001), death from cardiac causes (p = 0.045), from stroke (p><0.001), as well as the total number of adverse events (p><0.001) and disability (p = 0.065). Indications for reconstructive surgery on the lower extremities arteries (LEA), and operations frequency were comparatible in groups. Amputation history, taking diuretics, presence of rhythm disturbances, and management by a surgeon increased the risk of adverse outcomes. Management by a cardiologist, reconstructive LEA surgeries, female sex improved the prognosis of patients. Conclusion Observation of PAD patients by a cardiologist contributes to a higher frequency of optimal drug therapy by patients and can reduce the number of adverse events in patients and improve their survival without affecting the timing and frequency of reconstructive LEA surgeries. Keywords Peripheral atherosclerosis • Outpatient follow-up • Optimal drug therapy • Reconstructive surgery>˂ 0.001), death from cardiac causes (p = 0.045), from stroke (p˂ 0.001), as well as the total number of adverse events (p˂ 0.001) and disability (p = 0.065). Indications for reconstructive surgery on the lower extremities arteries (LEA), and operations frequency were comparatible in groups. Amputation history, taking diuretics, presence of rhythm disturbances, and management by a surgeon increased the risk of adverse outcomes. Management by a cardiologist, reconstructive LEA surgeries, female sex improved the prognosis of patients.Conclusion. Observation of PAD patients by a cardiologist contributes to a higher frequency of optimal drug therapy by patients and can reduce the number of adverse events in patients and improve their survival without affecting the timing and frequency of reconstructive LEA surgeries

Dysfunction of the meibomian glands in patients with diabetes mellitus

The prevalence of diabetes mellitus has increased in recent decades. The most common ophthalmic manifestations of diabetes mellitus are retinopathy, epitheliopathies, corneal erosion and dry eye syndrome, the symptoms of which are more pronounced than in people without diabetes. The meibomian glands, which are the producer of various lipids, participate in the formation of the lipid layer of the tear film, which prevents the evaporation of the water-mucin phase and ensures the preservation of homeostasis of the ocular surface. Meibum is a lipid-rich secret produced by fully differentiated meibocytes. Impaired insulin secretion, insulin resistance, absolute insulin deficiency, as well as hyperglycemia, potentiate the development of oxidative stress and a cascade of metabolic changes, leading to a change in the anatomical and functional state of the meibomian glands, which affects the qualitative and quantitative secretion. Cytological abnormalities, as well as the structure of the excretory ducts of the meibomian glands in patients with long-term diabetes mellitus, were established using the method of laser scanning microscopy. Using the method of mass spectrometry, it is possible to determine the patterns of changes in the chemical composition of meibum in patients with diabetes mellitus. The data obtained can become one of the criteria for predicting the course, reflect the degree of compensation and / or progression of diabetes mellitus

Electrochemical behavior of chloramphenicol on carbon electrodes in a microelectrochemical cell

Express determination of antibiotics is an extremely important task today. Portable electrochemical microdevices are a viable alternative to traditional methods of analysis. The development of such devices requires the study of redox processes in detail. This article is devoted to the comparative study of the electrochemical behavior of chloramphenicol in water solvents in standard laboratory and portable microelectrochemical cells. It was found that the electrochemical reduction of chloramphenicol proceeds via a 3-electron mechanism to the formation of a dimer. In the transition from the macrocell to the microcell, a decrease in the electrochemical reduction current and a shift of the peak potential to the cathode region are observed, which is apparently associated mainly with the type of the electrode material. The best characteristics of the direct electrochemical response were obtained in the differential pulse voltammetry mode. Under the selected operating parameters, the peak current of the electrochemical reduction of chloramphenicol is linearly dependent on the concentration of the antibiotic in the range of 2∙10–3–1∙10–5 M with a detection limit of 3∙10–5 M. Obtained characteristics are sufficient for the quality control of pharmaceuticals and can be improved through the use of organic and hybrid modifiers of the working electrode surface

Calculation scheme based on the extended equations of DMFT

This work was supported of grant program of the President of Russian Federation MD-6458.2016.2