Work hardening behavior in a steel with multiple TRIP mechanisms

Transformation induced plasticity (TRIP) behavior was studied in steel with composition Fe-0.07C-2.85Si-15.3Mn-2.4Al-0.017N that exhibited two TRIP mechanisms. The initial microstructure consisted of both {\epsilon}- and {\alpha}-martensites with 27% retained austenite. TRIP behavior in the first 5% strain was predominately austenite transforming to {\epsilon}-martensite (Stage I), but upon saturation of Stage I, the {\epsilon}-martensite transformed to {\alpha}-martensite (Stage II). Alloy segregation also affected the TRIP behavior with alloy rich regions producing TRIP just prior to necking. This behavior was explained by first principle calculations that revealed aluminum significantly affected the stacking fault energy in Fe-Mn-Al-C steels by decreasing the unstable stacking fault energy and promoting easy nucleation of {\epsilon}-martensite. The addition of aluminum also raised the intrinsic stacking fault energy and caused the {\epsilon}-martensite to be unstable and transform to {\alpha}-martensite under further deformation. The two stage TRIP behavior produced a high strain hardening exponent of 1.4 and led to ultimate tensile strength of 1165 MPa and elongation to failure of 35%.Comment: submitted to Met. Mater. Trans. A manuscript E-TP-12-953-

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

Effect of Phosphorus on Cleavage Fracture in Κ-Carbide

To understand the origin of cleavage fracture which dominates in Fe(Mn)-Al-C alloys at a high phosphorus concentration, we performed first-principles study of the phosphorus effect on ideal cleavage energy and critical stress in κ-carbide, Fe3 AlC, a precipitate in the austenitic alloys. We find that phosphorus has higher solubility in Fe3 AlC than in γ-Fe and sharply reduces the cleavage characteristics of κ-carbide. We show that strong anisotropy of the Fe-P bonds in Fe3 (Al,P) C under tensile stress, leads to the appearance of large structural voids and may facilitate crack nucleation

Tuning the properties of complex transparent conducting oxides: role of crystal symmetry, chemical composition and carrier generation

The electronic properties of single- and multi-cation transparent conducting oxides (TCOs) are investigated using first-principles density functional approach. A detailed comparison of the electronic band structure of stoichiometric and oxygen deficient In$_2$O$_3$, $\alpha$- and $\beta$-Ga$_2$O$_3$, rock salt and wurtzite ZnO, and layered InGaZnO$_4$ reveals the role of the following factors which govern the transport and optical properties of these TCO materials: (i) the crystal symmetry of the oxides, including both the oxygen coordination and the long-range structural anisotropy; (ii) the electronic configuration of the cation(s), specifically, the type of orbital(s) -- $s$, $p$ or $d$ -- which form the conduction band; and (iii) the strength of the hybridization between the cation's states and the p-states of the neighboring oxygen atoms. The results not only explain the experimentally observed trends in the electrical conductivity in the single-cation TCO, but also demonstrate that multicomponent oxides may offer a way to overcome the electron localization bottleneck which limits the charge transport in wide-bandgap main-group metal oxides. Further, the advantages of aliovalent substitutional doping -- an alternative route to generate carriers in a TCO host -- are outlined based on the electronic band structure calculations of Sn, Ga, Ti and Zr-doped InGaZnO$_4$. We show that the transition metal dopants offer a possibility to improve conductivity without compromising the optical transmittance

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

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

Factors Influencing Nurses’ Decision to Join a Professional Association in Russia

Received 26 October 2019. Accepted 21 June 2020. Published online 9 July 2020.Many professional associations of nurses in Russia and other countries struggle to increase their membership. Even though there are obvious advantages of membership in a professional organization, many people decide against it, which makes the study of factors that affect their decision-making a pertinent task. The aim of our research is to study the factors of membership or nonmembership of nurses in professional organizations in Russia. We conducted semi-structured interviews among nurses in different Russian regions (N = 16). Their responses were analyzed by qualitative content analysis. We identified the main factors that determine nurses’ membership or non-membership in professional associations and distinguished between objective and subjective reasons as well as active or passive attitudes demonstrated by our respondents in this regard. The conclusion is made that nurses often adopt a “formal” approach to membership in professional associations, seeing it primarily as a certification requirement. This means that their interests may not coincide with the goals and mission declared by these associations in their charters. Some respondents, however, demonstrated a more active attitude, pointing out such reasons for membership as professional growth, opportunities for advanced training, socialization, exchange of ideas and so on.This research was supported by the Russian Fund of Federal Property, project No. 18-013-01154А

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