Оптимізація вмісту добавок у епокси-поліефірному зв'язувачі для підвищення когезійної міцності композитів

Protective coatings of polymeric composites are proved to be effective in protecting metal surfaces from corrosion and wear. In order to create a polymeric composite material with improved cohesive properties, fillers of different nature and dispersion, modifiers and plasticizers should be introduced into the epoxy-polyester binder. For optimization of the content of components in epoxy-polyester binder, the method of orthogonal central compositional planning was used. Analysing the experimental obtained data, the regression equations for properties such as fracture stresses during the flexion and impact strength were obtained. For the statistical processing of the experimental results, testing of the reproducibility of experiments was performed on the Cochran criterion. Significance of regression coefficients was determined according to Student's criterion. The adequacy of the obtained model was confirmed by Fischer's criterion. According to the results received we have found that the introduction of two-component filler of different nature and dispersion affects the indices of fracture stresses during the flexion of composite material. It is proved that in order to create a composite with increased values of fracture stresses during the flexion, a discrete carbon fiber with particle sizes d = 6…8 μm, l = 0.5…1.5 mm – 0.05 pts. wt. and an oxidized nanodispersed additive with a dispersion d = 5…8 nm – 0.05…0.075 pts. wt. should be introduced per 100 pts. wt. of epoxy-polyester binder. At this content, the parameters of fracture stresses during the flexion increase to σfl = 72.6…75.5 MPa. Additionally, the effect of two-component filler on the impact strength of the developed epoxy-polyester composite was determined. It is analyzed that the introduction of a discrete carbon fiber at the content from 0.10 to 0.15 pts. wt. and an oxidized nano-dispersed additive at the content from 0.05 to 0.075 pts. wt. per 100 pts. wt. of the epoxy-polyester matrix allows to receive the increased indexes of the impact strength of the composite material (W = 9.1…9.4 kJ/m2). The obtained results allow creating a polymeric material with the improved parameters of cohesive properties in the complex.Доведено, що для захисту елементів металевих поверхонь від корозії та зношення ефективним є використання захисних полімерних композитних покриттів. Встановлено, що для створення полімерного композитного матеріалу з поліпшеними когезійними властивостями потрібно вводити в епокси-поліефірний зв'язувач наповнювачі різної природи та дисперсності, модифікатори та пластифікатори. Експериментально встановлено, що введення двокомпонентного наповнювача різної природи та дисперсності впливає на показники руйнівних напружень під час згинання композитного матеріалу. Методом ортогонального центрального композиційного планування експерименту доведено, що для створення композиту з підвищеними показниками руйнівних напружень під час згинання потрібно вводити дискретне вуглецеве волокно з розмірами часток d = 6…8 мкм, l = 0,5…1,5 мм – 0,05 мас. ч. та окиснену нанодисперсну добавку з дисперсністю d = 5…8 нм – 0,05…0,075 мас. ч. на 100 мас. ч. епокси-поліефірного зв'язувача. При цьому показники руйнівних напружень під час згинання підвищуються до σзг = 72,6…75,5 МПа. Додатково встановлено вплив двокомпонентного наповнювача на ударну в'язкість розробленого епокси-поліефірного композиту. Проаналізовано, що введення дискретного вуглецевого волокна за вмісту 0,10…0,15 мас. ч. та окисненої нанодисперсної добавки 0,05…0,075 мас. ч. на 100 мас. ч. епокси-поліефірної матриці дає змогу отримати підвищені показники ударної в'язкості композитного матеріалу (W = 9,1…9,4 кДж/м2). Отримані результати дають змогу створити полімерний матеріал із поліпшеними в комплексі показниками когезійних властивостей

CHARACTERIZATION OF AVIAN INFLUENZA H5N8 VIRUS STRAINS THAT CAUSED THE OUTBREAKS IN THE RUSSIAN FEDERATION IN 2016–2017

Objective of the study is to investigate biological properties of avian influenza virus strains that caused the outbreaks in Russia in 2016–2017.Materials and methods. The study was performed using advanced virological and molecular-biological methods in state-of-the-art equipment.Results and conclusion. In 2016, the outbreaks among wild birds and poultry caused by highly pathogenic avian influenza H5N8 virus have occurred in the territory of the Russian Federation. In May, 2016 an outbreak of H5N8 among wild birds was registered in the territory of the Republic of Tyva. In October-November, 2016 influenza virus H5N8 was isolated in the territory of the Republics of Tatarstan and Kalmykia, Krasnodar and Astrakhan Regions of Russia. In 2017 avian influenza H5N8 has become widespread in European part of Russia and caused multiple outbreaks among wild birds and poultry. Results of the investigations of the isolated strains show that all of them are highly pathogenic and belong to the clade 2.3.4.4. Molecular-genetic and virological analysis has revealed the differences between the viruses isolated in 2016–2017 and the virus of the same clade 2.3.4.4 that was isolated in 2014

Kinematyka dwupunktowego kontaktu koła z szyną

The railway transport in a maximum degree is conservative. For example, the design of wheelsets, practically, has not changed for the last 150 years. Such a long life was given to this tendency by its high reliability and simplicity of the design. It is considered, that the rigid connection of wheels by means of an axis provides a self-centering of wheelset within the limits of a cross backlash of a railway. The tread contact surfaces have a difficult profile. Researches of many scientists, dealing with the questions of interaction of wheels with rails, show that the classical approach to the wheelset design leads to many problems of the railway transport. Therefore, the authors of this article strived for deeper consideration of kinematics of a movement of vehicle by a railway

Use of fly larvae Hermetia illucens in poultry feeding: a review paper

The paper presents the review of scientific publications of world literature on the use of the larvae of black soldier fly (Hermetia illucens) when feeding poultry. Nowadays, the issue of replacing traditional sources of protein when feeding poultry is very urgent, especially in connection with the global food crisis. Insects are the natural food of most birds; thus, the use of fly larvae for feed production has a biological basis. The research results presented in published works show that there are no negative effects on bird health and meat quality when feeding poultry, quail and other birds. In some cases, the experimental groups of birds gained weight slightly more slowly than the control group. Other reports indicate that birds grew at the same rate as normal birds. The quantity and quality of eggs did not differ significantly, but dietary changes affected the colour of yolks and eggshell. The effect of the addition of live larvae to the diet of young turkeys on the weight characteristics of was studied. Replacing 10% of the daily amount of feed with live Hermetia illucens larvae in the diet of turkeys showed that the daily feed intake and body weight gain of the experimental birds were significantly higher compared to the control groups, which led to a significantly higher body weight of chicks at the age of five weeks (2.19 kg vs. 2.015 kg, respectively) and a significantly lower feed conversion rate. Most researchers agree that replacing protein in poultry feed with insect flour should be partial, in the 15–30% range. Feeding with larvae that have undergone processing – grinding, chitin removing, heat treatment – is more preferable than using whole larvae, since the chitinous membrane makes larvae difficult to be digested in the digestive tract of birds

A Rare Case of Charcot-Mari-Tooth Disease Type 2S in a 20-year-old Man

Charcot-Marie-Tooth disease type 2 (CMT2S) is rare form of Charcot-Marie-Tooth disease (CMT) that is characterized by a mutation in the IGHMBP2 gene. This gene encodes a helicase superfamily member that binds a specific DNA sequence from the region of the immunoglobulin mu chain switch. Mutation of this gene leads to spinal muscle atrophy with respiratory distress type 1 and CMT2S. This case report presents a 20-year-old male with genetically confirmed CMT2S having clinical respiratory involvement and symmetrically involved lower extremities. DNA sequencing revealed a previously unknown heterozygous mutation in the exone 2 of the IGHMBP2 gene leading to the replacement of the amino acid in the 46 position of the protein (chr11q13.3: 68673587 G>C). These atypical features widen the clinical spectrum of CMT2S. In describing this clinical case, we also improve diagnostic management and try to increase the alertness of various doctors towards neuromuscular diseases, including CMT