Influence of static tensile testing on the deformation behavior of Al–4% Cu alloy containing micro- and nanoparticles

At present, aluminum alloys reinforced with nonmetallic particles are of great interest in various fields of science and technology due to their high specific strength, hardness, wear resistance, and other properties. At the same time there is a great interest in the study of processes occurring during plastic deformation of such materials under static tensile loading. Plastic flow of metals occurs through the creation and movement of linear defects (dislocations), in which there is a phenomenon of discontinuous yielding. An introduction of particles into aluminum alloy promotes a considerable increase of stiffness and specific strength of alloys, and the study of the deformation behavior of such alloys is of great interest. The objective of this research is to analyze mechanical properties and the deformation behavior of aluminum alloy with the identification of mechanisms of plastic deformation when introducing solid nonmetallic micro- and nanoparticles into the soft aluminum matrix. An analysis of the microstructure of the obtained alloys shows that the introduction of particles (Al2O3, TiB2, TiC) leads to a reduction of the alloy grain size from 350 to 170 µm while residual porosity does not exceed 2%. Tensile tests performed show that the change in the type and quantity of particles also changes characteristics of discontinuous yielding, thus resulting in an increase of yield strength (from 18 to 40 MPa), reduction of ductility (from 15 to 2%), and moreover a significant increase of tensile strength (from 77 to 130 MPa), as compared to the initial Al–4 wt % Cu alloy

Structure, phase content and mechanical properties of aluminium with hard particles after shock-wave compaction

The possibilities to combine metal and metal oxide powders in various compositions open a broad range of mechanical and thermal behavior. When using in nanostructured components the resulting materials might exhibit even more interesting properties, like product effectiveness, tensile strength, wear resistance, endurance and corrosion resistance. Intermetallics like TiAl could be obtained as TiAlx in a quality similar to that obtained from melting where only eutectic mixture can be produced. Similar effects are possible when compacting nanoceramic powders whereas these can be combined with intermetallics. Currently, it is very difficult to produce wires and special shaped parts from high temperature superconducting materials. The compacting by explosives could solve this problem.The present paper uses explosion compacting of Al nanoparticles to create nanocomposite with increased physico-mechanical properties. Russian civil explosive Uglenit was chosen as high energy material (HEM) for shock-wave compaction. The different schemes and conditions were suggested to run the explosion process. Al nanoparticles as produced by electric wire explosion contain 8-10% of aluminum oxide. That aluminum oxide can serve as strengthening material in the final nanocomposite which may be generated in various compositions by explosive compacting. Further modifications of nanocomposites were obtained when including nanodiamonds into the mixture with aluminum nanoparticles with different percentages. The addition of nanodiamonds results in a substantial strengthening effect

Application of external fields to the development of aluminum-based nanocomposite and master alloys

Application ultrasonic cavitation and high-energy pulses (e.g. detonation) is a promising way of incorporating reinforcing and grain refining particles in composite and master alloys. This paper gives an overview of research performed recently on the development of new technological approaches and materials with the aim to introduce and distribute nanoparticles in the matrix of aluminum alloys. Both types of particles, introduced externally or formed insitu are discussed. External fields are used for making concentrated master alloys, e.g. Alalumina with subsequent introduction of such a master alloy into the melt with the aid of ultrasonic cavitation; or for direct production of nanocomposites. The examples of implementation include Al-based composites reinforced with nanodiamonds, nanoalumina and nanospinel. The efficiency is illustrated by structure and properties characterization. The research is done within a European program on the application of external fields in liquid metal processing Exomet (EC grant 280421).The authors acknowledge financial support from the Exomet Project (which is co-funded by the European Commission in the 7th Framework Programme (contract FP7-NMP3-LA-2012-280421), by the European Space Agency and by the individual partner organisations)

Comorbidades psiquiátricas em adolescentes internados com transtorno de uso de substâncias

Orientador: Prof. Dr. Gustavo Manoel S. DóriaDissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências da Saúde, Programa de Pós-Graduação em Saúde da Criança e do Adolescente. Defesa : Curitiba, 25/11/2016Inclui referências: p. 74-88Resumo: O objetivo desse estudo é avaliar as comorbidades psiquiátricas em adolescentes com Transtorno de Uso de Substâncias (TUS) internados na cidade de Curitiba. O abuso de substâncias e a presença de comorbidades psiquiátricas na adolescência, aumenta o comportamento disfuncional do adolescente, o coloca em riscos (evasão escolar, gestações indesejadas, criminalidade, homicídio, suicídio), chegando a ser um problema de saúde pública. O TUS na adolescência se tornou um grande problema social e de saúde. A idade da primeira experimentação tem diminuido e a precocidade do uso aumenta o risco para desenvolver dependência e outros transtornos psiquiátricos. Espera-se que grande parte dos adolescentes dependentes de substâncias apresentem comorbidades psiquiátricas. A versão brasileira do Schedule for Affective Disorders and Schizophrenia for School Aged-Children (K-SADS-PL) foi aplicada a 35 adolescentes do sexo masculino que foram hospitalizados por TUS na cidade de Curitiba. Verificou-se que 92% dos adolescentes tinham alguma comorbidade psiquiátrica. As comorbidades mais frequentemente observadas foram o Transtorno de Conduta (TC) (57,1%), Transtorno de Déficit de Atenção e Hiperatividade (TDAH) (48,6%) e Transtorno opositor desafiante (TOD) (40,0%). A maconha (94,2%) e o crack (40,0%) foram as principais substâncias utilizadas pelos adolescentes. O uso de maconha esteve mais frequentemente associada a efeitos negativos sobre o comportamento e vida dos adolescentes. É de extrema importância avaliar os fatores que podem prevenir a progressão de um transtorno e/ou comorbidade para diminuir os prejuízos do desenvolvimento do adolescente e o custo gerado para o tratamento tardio. Desta forma, é necessária a implantação de serviços que atendam essa população. Palavras-chave: Transtornos Relacionados ao Uso de Substâncias. Psiquiatria Infantil. Psiquiatria do Adolescente. Transtornos Mentais.Abstract: The aim of this study is to evaluate psychiatric comorbidity in hospitalized adolescents with Substance Use Disorder (SUD) in the city of Curitiba. Substance abuse and the presence of psychiatric comorbidities in adolescence increases the dysfunctional behavior, puts him at risk (school dropout, unexpected pregnancies, criminality, homicide, suicide), becoming a public health problem. Substance Use Disorder in adolescence has become an important social and health problem. The age of first experimentation has decreased and the precocity of use increases the risk for dependence and other psychiatric disorders.It is expected that most of the adolescents with substance dependence have psychiatric comorbidities. The Brazilian version of the Schedule for Affective Disorders and Schizophrenia for School Aged-Children (K-SADS-PL) was applied to 35 male adolescents with SUD who were hospitalized in the city of Curitiba. It was found that 92% of adolescents had some psychiatric comorbidity. The most frequent comorbidities among adolescents of this present study were Conduct disorder (CD) (57.1%), Attention deficit hyperactivity disorder (ADHD) (48.6%) and Oppositional defiant disorder (ODD) (40.0%). Marijuana (94.2%) and crack (40.0) were the main substances used by adolescents. The use of marijuana was the most frequently associated with negative effects on the behavior and lives of adolescents. It is very important to assess the factors that can prevent the natural progression of a disorder and/or comorbidity to reduce the impairment of the adolescent development and the cost for late treatment. Thus, the development of services that support this population is needed. Keyword: Substance-Related Disorders. Child Psychiatry. Adolescent Psychiatry. Mental Disorders

On the evaporation dynamics of trinitrotoluene microparticles on the glass surface

The results of measuring the time dependence of the concentration of trinitrotoluene (TNT) vapor over its solid microconcentrations on the glass surface with a low TNT concentration on the surface of 100 ng/cm2 are presented. Such microconcentrations of traces are typical for the conditions of anti-terrorist control of objects for the presence of TNT. The measurements were made using a portable multicapillary gas chromatograph (GC) EKHO-V-IDTS (Russia) with TNT vapor concentration. The threshold for determining the concentration of TNT vapor by the EKHO-V-IDTS gas chromatograph corresponds to the modern level and is equal to 10-14 g/cm3. Vapor sampling is performed by a vortex sampling device (VSD), which is used in the anti-terrorist control of objects. It is shown that the initial surface concentration of TNT traces of 100 ng/cm2 on the glass surface decreases to 12 ng/cm2 in a time of 2.6 h due to evaporation into an open half-space under laboratory conditions. The vapor concentration over the residual TNT concentration of 12 ng/cm2 corresponds to the GC sensitivity threshold for TNT vapor concentration equal to 10-14 g/cm3

Study of the effect of diamond nanoparticles on the structure and mechanical properties of the medical Mg–Ca–Zn magnesium alloy

The paper addresses the production and investigation of the Mg–Ca–Zn alloy dispersionhardened by diamond nanoparticles. Structural studies have shown that diamond nanoparticles have a modifying effect and make it possible to reduce the average grain size of the magnesium alloy. Reduction of the grain size and introduction of particles into the magnesium matrix increased the yield strength, tensile strength, and ductility of the magnesium alloy as compared to the original alloy after vibration and ultrasonic treatment. The magnesium alloy containing diamond nanoparticles showed the most uniform fracture due to a more uniform deformation of the alloy with particles, which simultaneously increased its strength and ductilit

On elliptic solutions of the quintic complex one-dimensional Ginzburg-Landau equation

The Conte-Musette method has been modified for the search of only elliptic solutions to systems of differential equations. A key idea of this a priory restriction is to simplify calculations by means of the use of a few Laurent series solutions instead of one and the use of the residue theorem. The application of our approach to the quintic complex one-dimensional Ginzburg-Landau equation (CGLE5) allows to find elliptic solutions in the wave form. We also find restrictions on coefficients, which are necessary conditions for the existence of elliptic solutions for the CGLE5. Using the investigation of the CGLE5 as an example, we demonstrate that to find elliptic solutions the analysis of a system of differential equations is more preferable than the analysis of the equivalent single differential equation.Comment: LaTeX, 21 page

The physical-mechanical and electrical properties of cast aluminum-based alloys reinforced with diamond nanoparticles

The results obtained from investigations into the microstructure and physical-mechanical and electrical properties of cast aluminum-based alloys reinforced with nanodiamonds are presented. Addition of the diamond nanoparticles is shown to change the structural parameters and improve the mechanical properties of the materials.The work was financed by the Ministry of Education and Science of the Russian Federation within the Federal Target Program “Scientific and Scientific-Pedagogical Personnel of Innovative Russia” for 2014–2020 (Agreement № 14.578.21.0025, UID RFME157814X0025) and the Program to Improve the Competitiveness of Tomsk State University among the World Leading Research and Education Centers