On Boussinesq-type models for long longitudinal waves in elastic rods

In this paper we revisit the derivations of model equations describing long nonlinear longitudinal bulk strain waves in elastic rods within the scope of the Murnaghan model in order to derive a Boussinesq-type model, and extend these derivations to include axially symmetric loading on the lateral boundary surface, and longitudinal pre-stretch. We systematically derive two forced Boussinesq-type models from the full equations of motion and non-zero surface boundary conditions, utilising the presence of two small parameters characterising the smallness of the wave amplitude and the long wavelength compared to the radius of the waveguide. We compare the basic dynamical properties of both models (linear dispersion curves and solitary wave solutions). We also briefly describe the laboratory experiments on generation of bulk strain solitary waves in the Ioffe Institute, and suggest that this generation process can be modelled using the derived equations.Comment: 19 pages, 5 figures, submitted to the Special Issue of Wave Motion, "Nonlinear Waves in Solids", in Memory of Professor Alexander M. Samsono

Semantic and Syntactic Features of Constructions with the Meaning of Measure and Degree in Russian

The syntactic structures, that are intended in Russian to express the meaning of measure and degree, are discussed in the article. The relevance of the study is due to the problems of modern syntax, which is aimed at a multidimensional analysis of syntactic structures and the study of the functions of service words involved in their organization. The work was carried out in the traditions of the Vladivostok scientific school, which applied the “from construction” approach to the analysis of syntactic units. It is indicated that this term is used here in a narrow sense as a structure embedded in a complex sentence, having a certain set of components and a specific means of connecting these components. The novelty of the research is determined by the use of the concept of “construction” as the main tool for analyzing syntactic units with the meaning of measure and degree in the formal grammatical aspect. A features analysis of the formation of the semantics of measure and degree within the framework of syntactic structures is presented, the formal organization of these structures is described in detail: the component composition, the “core” of the structure — service complexes used to link components, the role of clarifiers and the possibility of phraseologization of the structure. It is noted that this study is important both for solving theoretical issues that relate to a versatile description of syntactic structures, and for teaching the syntax of the Russian language to foreign students

Separation of Q from carbon in CR meteorites during stepped combustion

Introduction: The nature of the planetary noble gas carrier (Q) in meteorites remains uncertain. It is known that it is likely to be carbonaceous, but represents only a small fraction of the total macromolecular material. Q is oxidisible with nitric and other oxidizing acids. It seems to be partly destroyed with pyridine and may have an organic structure. Previously, we have shown that during parent body thermal metamorphism Q is less affected than the majority of other carbonaceous materials. If organic matter is graphitized, as has happened in the enstatite chondrite parent bodies, Q remains unaffected. In the present study we have found that Q is also separable from the majority of carbon in type 2 and 3 CR chondrites during stepped combustion. It is possible that this is because Q has become encased within the matrix, in contrast to other carbon phases, during parent body metamorphism

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

The influence of the microstructure morphology of two phase Ti-6Al-4V alloy on the mechanical properties of diffusion bonded joints

The influence of ultra fine grained (UFG) and coarse grained (CG) microstructure of the titanium alloy Ti-6Al-4V on the strength of a diffusion bonded (DB) joint was studied using a laboratory DB fixture and a new shear test rig. The DB process was carried out at 725°C and 825°C during 2 and 4 hours in a vacuum furnace. Coarsening of grain structure resulting from different DB cycles was quantified. The chain pores were observed at 725°C for both microstructure conditions bonded during 2 hours. The increase of bonding time up to 4 hours leads to subsequent elimination of the pores. The UFG samples bonded at 725°C showed a higher level of the shear strength than CG samples for both bonding times. The CG material demonstrated the highest shear strength after 4 hours of DB bonding at 825°C. The increase of the creep deformation of UFG samples when compared to the CG condition was observed as a result of DB at of 725° C during 4 hours

РЕЗУЛЬТАТИ ОЦІНКИ ЯКОСТІ ЖИТТЯ ХВОРИХ НА ХРОНІЧНИЙ ПАНКРЕАТИТ ІЗ СУПУТНІМ ОСТЕОДЕФІЦИТОМ

Оцінка якості життя (ЯЖ) важлива прихронічних захворюваннях, що вимагають тривалоїтерапії, до яких відносяться як хронічний панкре-атит (ХП), так і остеодефіцит (ОД). Високе медико-соціальне значення ХП та ОД визначається їх зна-чним внеском у патологію людей соціально ак-тивного віку, великими витратами на діагностикуі лікування, зниженням ЯЖ і працездатності

ACTUAL PRINCIPLES OF THERAPY CHRONIC HEPATITIS OF VARIOUS ETIOLOGIES

The review analyzes the current understanding of the mechanisms of formation of liver fibrosis in chronic diffuse liver diseases. The urgency and importance of the clinical evaluation of the degree of fibrosis, are shown methods of early diagnosis of liver fibrosis and its progression are offered. The modern principles of treatment of chronic hepatitis of various etiologies based on numerous clinical and experimental studies described in domestic and foreign literature are presented. Detailed description of the main directions of comprehensive treatment program with the main characteristic of causal agents and pathogenetic therapy, the aim of which is to correct the universal units of liver fibrogenesis is shown. Reversibility of liver fibrosis at an effective antiviral therapy for patients with chronic viral hepatitis is convincinglu presented. At present time Further study of clinical and immunological aspects of fibrogenesis in chronic diffuse liver diseases for the improvement of anti-fibrotic therapy remains relevant