ПОВЫШЕНИЕ ТРЕЩИНОСТОЙКОСТИ АСФАЛЬТОБЕТОННЫХ ПОКРЫТИЙ

The methods used toincrease temperature resistance of bituminous concrete pavement are in the focus of researches in the sphere of road engineering which study first of all the bituminous concrete mixtures with polymer modified cementing bitumen. But the most common polymers of styrene-butadiene-styrene type, like DST-30–01, Kraton, Lupren LG, considerablyincrease costs of highways construction. That’s why the researchers have restarted study on possible use of the waist of tyre manufacturing as modifier.The study refers to the powder of discretely devulcanized rubber which serves as modifier under the name of Unirem.The authors’ technology permits to manufacture polymer astringent bitumen.Evaluation of low temperature properties of such material were conducted during typical testing according to AASHTO TP1 standard that figures on the list of specifications «Superpave».The tests revealed the data on crack resistance of rubber-bitumen cementing component of highways. A new method of analysis of deformation of cementing properties under low temperature and v aried speed of reconstruction of lost properties is proposed. The results of “dry” and “wet” modes for the initial and modified bitumen components are compared.Bringing in of rubber granules by “dry” mode doesn’t ensure stability of the properties of bituminous concrete pavement. While the introduction of the rubber granules into bitumen and concrete mixture together with rubber-bitumen cementing component positively affects crack growth resistance and reduces the total costs of highway construction.В статье представлены данные по трещиностойкости резинобитумного вяжущего компонента автодорожных покрытий. Предложен метод исследования характера деформаций вяжущих свойств при отрицательных температурах и разных скоростях восстановления потерянных качеств. Приведены результаты применения «сухого» и «мокрого» способов для исходного и модифицированного битумных компонентов. Показано, что введение резиновой крошки «сухим способом» не гарантирует стабильности свойств асфальтобетонного покрытия в период эксплуатации. В то же время наличие такой крошки в составе резинобитумного вяжущего компонента дает возможность заметно повысить трещиностойкость асфальтобетонного покрытия

SHS for Space Exploration

For over past years, interest of leading space agencies (NASA, JAXA, ESA, RSA, etc.) in SHS experiments under microgravity conditions has been increasingly growing. The first SHS experiments during a parabolic flight in Russia and aboard the MIR Space station gave promising results. Similar studies are now being carried out in various countries. The obtained data and assimilated experience have shown that SHS reactions can be used for (a) synthesis of high-porosity materials and regulation of structure formation in combustion products, (b) preparation of skeleton structures by combustion of particles suspended in vacuum, (c) generation of thermal energy, (d) generation of incandescent radiation, and (e) for in-space fabrication and in-situ repair works (welding, joining, cutting, coating, near-net-shape production, etc.). However, the results of the above studies (strongly scattered in the literature) still seem insufficient for elucidating the mechanism of combustion in. Indeed, the experiments were carried out by different researchers for a dozen of systems and for strongly different duration of microgravity (drop towers, parabolic flight of a plane, parabolic flight of a spacecraft, in space stations). No correlation has been made with the available data of SHS studies (oriented largely on practical implementation) in conditions of artificial gravity. In experiments, the combustion wave has enough time to spread over the sample while the structure formation, may not have. This implies that the process of wave propagation should always be identical, irrespective of the type of experimental technique and place of experiment. SHS experiments in space are attractive because (a) of low energy requirements, (b) processing cycle is short, (c) of process simplicity, (d) of versatility (wide range of suitable materials, and (e) the use of in-situ resources possible. To date, SHS experiments has already been performed aboard the International Space Station (ISS). Space technology has been developed for frontier exploration not only around the Earth orbit environment but also to the Moon, Mars, etc

Electric Conductivity and Gas-Sensing Properties of Nickel Ferrite Thin Films Formed by Ion-Beam Sputtering Deposition

Ferrites with composition of NiMnxFe1-xO4, (with x = 0 ÷ 1.0) have been synthesized by self-propagating high-temperature synthesis (SHS). The particle size of the synthesized ferrite powder was about 10 nm. Additional heat treatment at 1270 K during 50 min allowed us to obtained product with the single phase composition NiFe2O4.  We found out that the increasing of the manganese content (x) increased the lattice constant of the ferrites from 0.833896 nm (x = 0) up to 0.836369 nm (x = 1). The synthesized powder contains two types of ferrite particles that are varied in size and shape. The magnetic properties significantly depend on the microstructure and chemical composition of synthesized ferrites. It has been found that the coercive force Hc increased from 1.75 (x = 0.2) to 2.85 (x = 1). By using of IBSD technology thin film of NiFe2O4 was sputtered on the Si (100) substrate. All sputtered films were X-ray transparent. The structure of ferrite films consisted of agglomerate less than 35 nm. The thickness of the sputtered film was about 600 nm. Additional heat treatment at 770 K during 90 min resulted to homogeneity of the film microstructure. The temperature range 400-750 K corresponds to working temperature range of gas-sensing devices. The ferrite compounds were studied by TOF-SIMS (Time-of-Flight Secondary-Ion-Mass-Spectrometry) for all depth of film. The resistivity R of synthesized film was 39 kΩ. Measurement of gas-sensing sensitivity RCH4/Rair for gas (2%v. CH4) – air mixture showed increase of R up to 12% at the present of methane at 403 K. For further research we plan to replace iron to manganese ions in chemical compounds of ferrite

Development and external validation of a clinical prediction model for functional impairment after intracranial tumor surgery

OBJECTIVE Decision-making for intracranial tumor surgery requires balancing the oncological benefit against the risk for resection-related impairment. Risk estimates are commonly based on subjective experience and generalized num-bers from the literature, but even experienced surgeons overestimate functional outcome after surgery. Today, there is no reliable and objective way to preoperatively predict an individual patient's risk of experiencing any functional impair-ment. METHODS The authors developed a prediction model for functional impairment at 3 to 6 months after microsurgical resection, defined as a decrease in Karnofsky Performance Status of >= 10 points. Two prospective registries in Swit- zerland and Italy were used for development. External validation was performed in 7 cohorts from Sweden, Norway, Germany, Austria, and the Netherlands. Age, sex, prior surgery, tumor histology and maximum diameter, expected major brain vessel or cranial nerve manipulation, resection in eloquent areas and the posterior fossa, and surgical approach were recorded. Discrimination and calibration metrics were evaluated. RESULTS In the development (2437 patients, 48.2% male; mean age +/- SD: 55 +/- 15 years) and external validation (2427 patients, 42.4% male; mean age +/- SD: 58 +/- 13 years) cohorts, functional impairment rates were 21.5% and 28.5%, respectively. In the development cohort, area under the curve (AUC) values of 0.72 (95% CI 0.69-0.74) were observed. In the pooled external validation cohort, the AUC was 0.72 (95% CI 0.69-0.74), confirming generalizability. Calibration plots indicated fair calibration in both cohorts. The tool has been incorporated into a web-based application available at https://neurosurgery.shinyapps.io/impairment/. CONCLUSIONS Functional impairment after intracranial tumor surgery remains extraordinarily difficult to predict, al- though machine learning can help quantify risk. This externally validated prediction tool can serve as the basis for case by-case discussions and risk-to-benefit estimation of surgical treatment in the individual patient.Scientific Assessment and Innovation in Neurosurgical Treatment Strategie

The Comparative Analysis of Social Success of Youth in Different Social Groups

In article the concept “success” and “social success” is considered. The author has conducted a research which purpose consisted in the comparative analysis of the level of development of social success in three social groups: volunteers are the people who are engaged in public work (volunteer activity), models — people who develop themselves (model activity), others (conditionally) are people not belonging to the above groups.В статье рассматривается понятие «социальная успешность». Автором проведено исследование, цель которого состояла в сравнительном анализе уровня развития социальной успешности в трех социальных группах: волонтеры — люди, занимающиеся общественной деятельностью, модели — люди, занимающиеся развитием себя, другие или пассивные — люди, не относящиеся к вышеназванным группам

BIOLOGICAL ACTIVITY OF CARBONIC NANO-STRUCTURES-COMPARISON VIA ENZYMATIC BIOASSAY

Purpose: The aim of the work is to compare the biological activity of carbonic nano-structures of natural and artificial origination, namely, humic substances (HS) and fullerenols. Materials and methods: The representative of the fullerenol group, С 60 О y (OH) x where у + x = 20–22, was chosen. Enzyme-based luminescent bioassay was applied to evaluate toxicity and antioxidant properties of HS and fullerenol (F); chemiluminescent luminol method was used to study a content of reactive oxygen species (ROS) in the solutions. Toxicity of the bioactive compounds was evaluated using effective concentrations ЕС 50 ; detoxification coefficients D OxT were applied to study and compare antioxidant activity of the compounds. Antioxidant activity and ranges of active concentrations of the bioactive compounds were determined in model solutions of organic and inorganic oxidizers—1,4-benzoquinone and potassium ferricianide. Results and discussion: Values of ЕС 50 revealed higher toxicity of HS than F (0.005 and 0.108 g L −1 , respectively); detoxifying concentrations of F were found to be lower. Antioxidant ability of HS was demonstrated to be time-dependent; the 50-min preliminary incubation in oxidizer solutions was suggested as optimal for the detoxification procedure. On the contrary, F’ antioxidant effect demonstrated independency on time. Antioxidant effect of HS did not depend on amphiphilic characteristics of the media (values of D OxT were 1.3 in the solutions of organic and inorganic oxidizers), while this of F was found to depend: it was maximal (D OxT = 2.0) in solutions of organic oxidizer, 1,4-benzoquinone. Conclusions: Both HS and F demonstrated toxicity and low-concentration antioxidant ability; however, quantitative characteristics of their effects were different. The differences were explained with HS polyfunctionality, higher ability to decrease ROS content, non-rigidity, and diffusion restrictions in their solutions. Antioxidant effect of the bioactive compounds was presumably attributed to catalytic redox activity of their π-fragments. The paper demonstrates a high potential of luminescent enzymatic bioassay to study biological activity of nano-structures of natural and artificial origination