Polystyrene-based nanocomposites with different fillers: fabrication and mechanical properties

The paper presents a comprehensive analysis of elastic properties of polystyrene-based nanocomposites filled with different types of inclusions: small spherical particles (SiO2 and Al2O3), alumosilicates (montmorillonite, halloysite natural tubules and Mica) and carbon nanofillers (carbon black and multi-walled carbon nanotubes). Composites were fabricated by melt technology. The analysis of composite melts showed that the introduction of Montmorillonite, Multi-walled carbon nanotubes, and Al2O3 particles provided an increase in melt viscosity by an average of 2 to 5 orders of magnitude over the pure polystyrene. Block samples of composites with different filler concentrations were prepared, and their linear and nonlinear elastic properties were studied. The introduction of more rigid particles led to a more profound increase in the elastic modulus of the composite, with the highest rise of about 80% obtained with carbon fillers. Carbon black particles provided also an enhanced strength at break of about 20% higher than that of pure polystyrene. The nonlinear elastic moduli of composites were shown to be more sensitive to addition of filler particles to the polymer matrix than the linear ones. The nonlinearity coefficient $\beta$ comprising the combination of linear and nonlinear elastic moduli of a material demonstrated considerable changes correlating with changes of the Young's modulus. The absolute value of $\beta$ showed rise in 1.5-1.6 times in the CB- and HNT-containing composites as compared to that of pure PS. The changes in nonlinear elasticity of fabricated composites were compared with measurements of the parameters of bulk nonlinear strain waves in them. Variations of wave velocity and decay decrement correlated with observed enhancement of materials nonlinearity

Эталон для измерения относительных величин структур позвоночника взрослых

The paper proposes a method for using the relative values of linear dimensions for spine structures, which are necessary to compare the results obtained from digital and conventional radiographs having different scales.The purpose of the study: to develop a method for quantifying the spine structures of adult patients in relative units of measurement.Materials and methods. Using digital spine radiographs of 141 patients (from 21 to 88 years old), with careful observance of the same magnification, it is shown that the metric length of the segment tangent to the image of the vertebral body CI lower contour – the órel standard – has no age trend.Results and discussion. The ratio of segment tangent to the image of sacrum upper contour (segment s) and órel standard dimension also does not depend on age and is on average equal to 2.1. So the segment can be approximately calculated as órel = s/2.1. A group of 64 patients, from 21 to 88 years old, taken from the general cohort is divided into four age subgroups according to the WHO classification. It is shown that relative vertical spine size decreases with age. The difference in average relative vertical spine size for the first and the fourth age subgroups was 3.75 órels. The relative contribution of each spine part to the decrease is also demonstrated.Conclusion. The proposed relative unit of measurement “órel” can be used as a universal measure of length, independent of the scale and method of obtaining an X-ray image for measuring and comparing the structures of the spine in adults at any age.В работе предложен метод измерения относительных величин линейных размеров структур позвоночника, которые необходимы для сравнения результатов, полученных с цифровых и обычных рентгенограмм, имеющих разный масштаб.Цель исследования: разработать метод количественной оценки величины структур позвоночника взрослых пациентов в относительных единицах измерения.Материал и методы. На примере группы из 141 пациента (от 21 до 88 лет) при тщательном соблюдении одинакового увеличения цифровых рентгенограмм было показано, что метрическая длина отрезка касательной к изображению нижнего контура тела позвонка CI – эталон óрел – не имеет возрастного тренда.Результаты и обсуждение. Выявлено, что соотношение размеров эталона óрел (отрезка orel) и отрезка касательной к изображению верхнего контура крестца (отрезка s) не зависит от возраста и в среднем равно 2,1, и может быть приблизительно вычислено по формуле orel = s/2,1. На примере группы 64 пациентов, взятых из той же когорты обследованных, (от 21 до 88 лет), разделенной на 4 возрастные подгруппы в соответствии с классификацией ВОЗ, показано, что относительный вертикальный размер позвоночника, уменьшается с возрастом. Разница средних относительных значений вертикального размера позвоночника в первой и в четвертой возрастной подгруппе составила 3,75 óрела. Также продемонстрирован относительный вклад каждого отдела позвоночника в это уменьшение.Заключение. Предлагаемая относительная единица измерения “óрел” может быть использована в качестве универсальной меры длины, независимой от масштаба и способа получения рентгеновского изображения для измерения и сравнения структур позвоночника у взрослых в любом возрасте

Evaluating extreme flood characteristics of small mountainous basins of the Black Sea coastal area, Northern Caucasus

The probability of heavy rains and river floods is expected to increase with time in the Northern Caucasus region. Densely populated areas in the valleys of small mountainous watersheds already frequently suffer from catastrophic peak floods caused by intense rains at higher elevations. This study aimed at assessing the flood characteristics of several small basins in the piedmont area of the Caucasus Mountains adjacent to the Black Sea coast including ungauged Cemes River in the Novorossiysk city. The Deterministic-Stochastic Modelling System which consists of hydrological model Hydrograph and stochastic weather generator was applied to evaluate extreme rainfall and runoff characteristics of 1% exceedance probability. Rainfall intensity is shown to play more significant role than its depth in formation of extreme flows within the studied region

Directions to improve economic efficiency of regional production

The paper provides theoretical grounding and the directions for improving the economic efficiency of the regional feedstuff production. The study develops a conceptual model of distributing management functions of feedstuff production between the regional authorities of state sectoral and economic management and the district level. The authors suggest the methodology for calculating potential capacity of intraregional feedstuff market, considering the demands of all categories of agricultural manufacturers. The study examines possibilities for implementing the strategy of diversified growth and development of the intraregional feedstuff market, including the terms of interaction between the large and micro-business inside the industry and cooperation of micro-business feedstuff manufacturers with agricultural production. The authors have developed the methodology for assessing the efficiency of feedstuff production, based on the aggregate estimation of the management organization, conditions for the development of feedstuff production and changes in the feedstuff production and livestock breeding industry.peer-reviewe

ABOUT STABILITY OF THE MEDICAL INSTITUTION

The work shows the geometrical and mathematical descriptions of stability of a medical institution structures, depending on the epidemiological and information well-beings

Two ideals connected with strong right upper porosity at a point

Let $SP$ be the set of upper strongly porous at $0$ subsets of $\mathbb R^{+}$ and let $\hat I(SP)$ be the intersection of maximal ideals $I \subseteq SP$. Some characteristic properties of sets $E\in\hat I(SP)$ are obtained. It is shown that the ideal generated by the so-called completely strongly porous at $0$ subsets of $\mathbb R^{+}$ is a proper subideal of $\hat I(SP).$Comment: 18 page

Strawberry resistance to the major fungal phytopathogens: R-genes and their DNA markers

The garden strawberry Fragaria × ananassa (Duchesne ex Weston) Duchesne ex Rozier (1785) is a perennial herbaceous plant of the Rosaceae family; it is cultivated all around the world. It accounts for more than half of the global volume of berries production. In Russia, more than 160 tons of garden strawberries are grown annually, but according to Russian scientists, this crop has a much higher productivity potential. Various pathogens, including bacterial, viral and fungal infections, negatively affect the productivity of strawberry. Anthracnose (caused by Colletotrichum Corda.), crown rot (Phytophthora cactorum Lebert & Cohn), red core disease (Phytophthora fragariae var. fragariae Hickman), fusarium wilt (Fusarium oxysporum f. sр. fragariae Winks & Williams ) and strawberry powdery mildew (Podosphaera aphanis [Sphaerotheca macularis] (Wallr.) U. Braun & S. Takam) are among the most important fungal diseases of strawberry. This review discusses the current data about the known genes and quantitative trait loci (QTLs) associated with resistance to listed plant pathogens. The review also offers information about molecular markers of different types: SDRF, AFLP, SSR, SCAR, SNP, associated with these genes/QTLs and used in the molecular screening of strawberry collections for practical purposes