Applications of Nanostructural NiTi Alloys for Medical Devices

New nanostructural shape memory alloy (55.91 wt% of Ni and 44.03 wt% of Ti) for the production of minimally invasive implantation medical devices (stents) was tested for corrosion resistance under static conditions by dipping it into solutions with various acidities (pH from 1.68 to 9.18) for 2 years, for static mechanical properties and for biocompatibility. The material for investigations was 280‐μm wires before and after thermal treatment at 450°C for 15 min in air and surface mechanical treatment. The characteristic image and size of grains were determined using the transmission electron microscope (TEM), and the phase composition; surface morphology; and the layer‐by‐layer composition were investigated using an X‐ray diffractometer; a scanning electron microscope (SEM); and an Auger spectrometer. The nickel release from the investigated nanostructural nitinol is less in comparison with data for microstructural nitinol in a solution of any acidity. Dissolution in the alkali medium is absent. A significant retardation of the nickel ion release (and insignificant concentration as a whole) and the absence of titanium ion release in the weakly acidic and neutral solutions with polished samples are observed. A simultaneous 7–11% increase in strength and plasticity in comparison with microstructural nitinol was attained. Toxicity of samples has not been revealed

Using of Magnetron Sputtering for Biocompatible Composites Creating

Biocompatible composites obtained using the magnetron sputtering for the production of minimally invasive implantation medical devices (stents) were investigated. Nano- and microdimensional surface layers of Ta, Ti, Ag, and Cu on flat and wire NiTi, Cu, Ti, and SiO2 substrates were created. The phase composition, surface morphology, and the layer-by-layer composition were investigated on an X-ray diffractometer, SEM, and Auger spectrometer. It was shown that the thickness and the structure of surface layers were affected by the sputtering distance, time, power, and the bias voltage at the substrate. The presence of the transition layer that contains both substrate and target elements and provides high adhesion of the surface layer to the substrate has been demonstrated. The material was tested for corrosion resistance under static conditions by dipping into solutions with various acidities (pH from 1.68 to 9.18) for 2 years, static mechanical properties, and biocompatibility in vitro and in vivo. A slight corrosive dissolution was observed only in a medium with a pH of 1.56. Dissolution in the other media is absent. An increase in strength and plasticity in comparison with substrate was attained depending on the nature of the sputtered substance and substrate. Toxicity of samples has not been revealed

Level Anticrossing of Impurity States in Semiconductor Nanocrystals

The size dependence of the quantized energies of elementary excitations is an essential feature of quantum nanostructures, underlying most of their applications in science and technology. Here we report on a fundamental property of impurity states in semiconductor nanocrystals that appears to have been overlooked—the anticrossing of energy levels exhibiting different size dependencies. We show that this property is inherent to the energy spectra of charge carriers whose spatial motion is simultaneously affected by the Coulomb potential of the impurity ion and the confining potential of the nanocrystal. The coupling of impurity states, which leads to the anticrossing, can be induced by interactions with elementary excitations residing inside the nanocrystal or an external electromagnetic field. We formulate physical conditions that allow a straightforward interpretation of level anticrossings in the nanocrystal energy spectrum and an accurate estimation of the states\u27 coupling strength

Verwey-Type Charge Ordering and Site-Selective Mott Transition in Fe₄O₅ under Pressure

The metal–insulator transition driven by electronic correlations is one of the most fundamental concepts in condensed matter. In mixed-valence compounds, this transition is often accompanied by charge ordering (CO), resulting in the emergence of complex phases and unusual behaviors. The famous example is the archetypal mixed-valence mineral magnetite, Fe3O4, exhibiting a complex charge-ordering below the Verwey transition, whose nature has been a subject of long-time debates. In our study, using high-resolution X-ray diffraction supplemented by resistance measurements and DFT+DMFT calculations, the electronic, magnetic, and structural properties of recently synthesized mixed-valence Fe4O5 are investigated under pressure to ∼100 GPa. Our calculations, consistent with experiment, reveal that at ambient conditions Fe4O5 is a narrow-gap insulator characterized by the original Verwey-type CO. Under pressure Fe4O5 undergoes a series of electronic and magnetic-state transitions with an unusual compressional behavior above ∼50 GPa. A site-dependent collapse of local magnetic moments is followed by the site-selective insulator-to-metal transition at ∼84 GPa, occurring at the octahedral Fe sites. This phase transition is accompanied by a 2+ to 3+ valence change of the prismatic Fe ions and collapse of CO. We provide a microscopic explanation of the complex charge ordering in Fe4O5 which “unifies” it with the behavior of two archetypal examples of charge- or bond-ordered materials, magnetite and rare-earth nickelates (RNiO3). We find that at low temperatures the Verwey-type CO competes with the “trimeron”/“dimeron” charge ordered states, allowing for pressure/temperature tuning of charge ordering. Summing up the available data, we present the pressure–temperature phase diagram of Fe4O5

Assessment of physicians’ and senior medical students’ knowledge in treatment of patients with community acquired pneumonia: Current results of the KNOCAP project

Introduction. Community-acquired pneumonia (CAP) remains one of the most acute problems of bronchopulmonary pathology being the 4th in the mortality structure (after cardiovascular, cerebrovascular diseases and malignant neoplasms) and the 1st among all fatalities from infectious diseases. Thanks to the scientific progress achieved in the antibiotic therapy and vaccine prophylaxis, the death toll has decreased four times compared to its rate during the “pre-antibiotic era“. However, nowadays there is a steadily increasing trend in the pneumonia mortality rate in Russia. The only possible way to increase efficacy of CAP treatment is timely initiated rational antibiotic therapy, considering the possible etiologies, risk factors and the severity of the patient’s condition. Materials and methods. The article represents the results of anonymous prospective surveys within the framework of the KNOCAP multi-centered research project aimed at accessing the knowledge on the fundamental issues in diagnosis and treatment of community-acquired pneumonia. The survey involved 222 students in their fifth- and sixth years in medical institute from Belgorod, Dnepr (Dnipro), Voronezh, Kiev (Kyiv) and Saratov and 110 physicians from Krasnodar, Saratov, Belgorod and Dnepr.Results and discussion. According to the results of the survey, such levels of correct answers were given by doctors and students, respectively: the inadmissibility of antimicrobial therapy (AMT) delay in CAP - 82% and 59%; the main criterion for withholding AMT - 56% and 37%; “sequential therapy” - 61% and 59%. At the same time, only 24% of the students and 23% of the physicians surveyed correctly reported typical mistakes in the treatment of a non-severe CAP with 50% or more accuracy; and in case of initial treatment, the number of correct responses was less than 28% for students and 45% for doctors. Conclusion. The survey showed that both senior medical students majoring in Medical Care and general practitioners had a low level of knowledge in CAP treatment. Hence, curricula need to be adjusted both in medical universities and in health institutions for practitioners in order to inform them and, thus, improve the quality of their knowledge in this field

Assessment of physicians’ and senior medical students’ knowledge in treatment of patients with community-acquired pneumonia: Current results of the KNOCAP project

Community-acquired pneumonia (CAP) remains one of the most acute problems of bronchopulmonary pathology being the 4th in the mortality structure (after cardiovascular, cerebrovascular diseases and malignant neoplasms) and the 1st among all fatalities from infectious diseases. Thanks to the scientific progress achieved in the antibiotic therapy and vaccine prophylaxis, the death toll has decreased four times compared to its rate during the “pre-antibiotic era“. However, nowadays there is a steadily increasing trend in the pneumonia mortality rate in Russia. The only possible way to increase efficacy of CAP treatment is timely initiated rational antibiotic therapy, considering the possible etiologies, risk factors and the severity of the patient’s condition

Cognitive Aspects of Athlete Activity

Article is devoted to the issues of symbolic mediation and diagnostic of time perception in sport. Distinction between iconic and symbolic mediation is discussed. Evidences of effective implementation of symbolic mediation in sport are examined. Means of optimization of sportsmen and sportswomen training by the instrumentality of symbol are considered. The results of time perception diagnostic of Russian synchronized swimmers are described. It was shown that sportswomen are greatly varied in accuracy and stability of reproduction of long (2–5 sec) and estimation of short (less than 250 ms) time intervals, which were filled with different contents – ticks of metronome, persistent sound, pressuring the button and etc. The improvement of individual characteristics of time perception is an important psychological resource of sports achievements increase

Interrupted thermal desorption of TiH2

Structural changes of commercial TiH2 were studied using interrupted temperature desorption spectroscopy and X-ray diffraction techniques to understand the mechanism of its degradation under non-equilibrium conditions. Rapid cooling on different stages of temperature-programmed heating allowed to study the intermediate phase compositions that evolve upon cooling from the high-temperature phase beta Ti(H). The phase transformation sequence is described as a number of consecutive reactions corresponding to the observed desorption peaks. Phases delta TiH2-x, gamma TiH, and the solid solution alpha Ti(H) were found to be intermediates in the epsilon TiH2 --> alpha Ti transformation when the latter is interrupted. Additional evidence for the thermodynamic stability of gamma TiH is given. (C) 2009 Elsevier B.V. All rights reserved.RFBR [07-03-00610]; INTAS [05-1000005-7672