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

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

A non-quadratic criterion for stability of forced oscillations and its application to flight control

A new test for stability of forced oscillations in nonlinear systems is applied to a marginally stable plant of the second order with a saturated PID-control and a harmonic reference signal. The range of its frequencies and amplitudes that guarantee stability of the forced oscillations is found. This result is used for stability analysis of an aircraft roll angle control system

Structure and Properties of CrN/TiN Multi-Layer Coatings Obtained by Vacuum-Arc Plasma-Assisted Deposition Method

The paper presents the study results of CrN/TiN multi-layer coatings, as well as single-layer TiN and CrN coatings on Cr12MoV cold work die steel deposited by the vacuum-arc plasma-assisted method. Three CrN/TiN coatings of 8-, 16-, and 32-layers were deposited, in which the thickness of each layer was 500 nm, 250 nm and 125 nm, respectively. All of the coatings reveal a face-centered cubic structure with highly oriented (111) growth. The hardness of the CrN/TiN multi-layer coatings was about 27 GPa. Changing the architecture of CrN/TiN multi-layer coatings by reducing the thickness of the CrN and TiN layers from 500 nm to 125 nm promotes a smooth decrease in both the wear parameter and the coefficient of friction. By using an X-ray phase analysis with synchrotron radiation, it was found that 32-layer CrN/TiN coating retained thermal stability during heating in air to a temperature of 1120–1125 °C, and in a vacuum at least to a temperature of 1200 °C

Reproductive Characteristics of Thawed Stallion Sperm

The main goal of our study was to determine a set of thawed stallion sperm characteristics that have predictive value for the pregnancy rate (PR) of mares after artificial insemination (AI). DNA fragmentation and survival of sperm during hypothermic storage were studied in addition to routinely determined semen characteristics such as concentration, percentage of motile spermatozoa, and morphology. To estimate DNA fragmentation, a modified hallo assay was applied. Sperm survival was determined within hours as the ability of spermatozoa to maintain progressive motility (PM) during the storage of ejaculate diluted with lactose-chelate-citrate-yolk (LCCY) medium at +4 °C. Strong positive correlation between PR and thawed sperm motility (r = 0.90, p < 0.05) as well as between PR and sperm survival (r = 084, p < 0.05) was revealed. There was also a strong negative correlation between PR and DNA damages in spermatozoa (r = −0.94, p < 0.05). We found no dependence of PR on normal morphology spermatozoa percentage in thawed semen. We concluded that the sperm activity, survival, and DNA fragmentation should be considered as the sufficient reproductive characteristics of semen to evaluate the quality of frozen/thawed sperm and prediction of PR