Is plastoquinone10-ox an antioxidant marker of red wines?

Research NoteAntioxidant activities of 20 different types of Slovak wines were examined. For the first time evidence of plastoquinone10-ox (PQ10-ox)) in red wines was documented. Twice higher levels of alpha-tocopherol (vitamin E) were determined in red wine varieties in comparison to white wine varieties. Enzymatic actitivities of superoxidedismutase (SOD) in all red wine varieties were higher compared to white wines; in some white wines they were not detectable. The beneficial effects of antioxidants are discussed, especially the role of coenzyme Q10 (analogue of plant PQ10-ox), vitamin E and SOD in preventing cardiovascular diseases. It is supposed that PQ10-ox could be an antioxidant marker of red wines. To prove the protective effect of a moderate consumption of red wine in human cardiology further studies are required

Barkhausen noise emission of AISI 304 stainless steel originating from strain induced martensite by shot peening

This study deals with magnetic Barkhausen noise emission produced by strain-induced martensite generated during shot peening of austenitic AISI 304 stainless steel. The transformation from the paramagnetic to ferromagnetic state and the corresponding birth of the magnetic domain structure are important with respect to irreversible motion of domain walls and the corresponding Barkhausen noise emission. Barkhausen noise is investigated and explained with respect to the residual stress state as well as the micro-structure expressed in terms of the martensite fraction, its crystallite size, preferred orientation, surface topography, and microhardness. The strength of the Barkhausen noise is mainly linked with the number of shot peening cycles, corresponding Almen intensity, and the associated volume fraction of strain-induced martensite as well as the extent of its depth. The role of the residual stress state in the martensite phase is minor. Surface strengthening expressed in terms of the microhardness in the near-surface region is very high for the medium shot peening intensity. A remarkable decrease in the near-surface microhardness as well as the presence of heavily thinned folds indicate over shot peen-ing and surface microcracking in the case of a longer shot peening time and the corre-sponding higher Almen intensity.Web of Science2076274

Effect of sintering temperature on microstructure and mechanical properties of AE42 magnesium alloy prepared by spark plasma sintering

Magnesium alloy AE42 was prepared by powder metallurgy technique of spark plasma sintering. The effect of sintering parameters, particularly sintering temperature, on the microstructure and mechanical strength was investigated. The gas-atomized powder was sintered at four temperatures in the temperature range of 400-550 °C. It was found that mechanical strength of the sintered samples was significantly affected by several microstructural features. Application of relatively high load during sintering caused deformation of the individual particles and consequent recrystallization depending on the processing temperature resulted in the release of internal strain and in grain growth. As a result, the evolution of the mechanical strength as a function of the sintering temperature was significantly affected by residual stress, grain size and coarsening of secondary phase particles

Substantially Higher Corrosion Resistance in AE42 Magnesium Alloy through Corrosion Layer Stabilization by ECAP Treatment

The corrosion properties of magnesium alloy AE42, just extruded and with posterior eight passes through equal channel angular pressing after extrusion, were investigated in 0.1 M NaCl by electrochemical impedance spectroscopy. The obtained samples were compared using scanning electron microscopy micrographs of the corrosion layers created on the surface of the specimens. The background of the substantial higher corrosion resistance of the samples after equal channel angular pressing treatment was found to be the much thicker and stable corrosion layer and smaller separating fragments in comparison with the just extruded samples. The lowering of the grain size by severe plastic deformation, especially by the equal channel angular pressing treatment was found to be also responsible for the enhancement of the corrosion resistance in AE42 class of magnesium alloys

Substantially Higher Corrosion Resistance in AE42 Magnesium Alloy through Corrosion Layer Stabilization by ECAP Treatment

The corrosion properties of magnesium alloy AE42, just extruded and with posterior eight passes through equal channel angular pressing after extrusion, were investigated in 0.1 M NaCl by electrochemical impedance spectroscopy. The obtained samples were compared using scanning electron microscopy micrographs of the corrosion layers created on the surface of the specimens. The background of the substantial higher corrosion resistance of the samples after equal channel angular pressing treatment was found to be the much thicker and stable corrosion layer and smaller separating fragments in comparison with the just extruded samples. The lowering of the grain size by severe plastic deformation, especially by the equal channel angular pressing treatment was found to be also responsible for the enhancement of the corrosion resistance in AE42 class of magnesium alloys

Observation of the microstructure of the metastable Ti15Mo alloy after ageing

Omega phase particles can be observed by conventional SEM. Metastable Ti15Mo alloy was annealed at 500 °C for 16 hours. During annealing, ω phase particles grew and got chemically stabilized by expelling Mo atoms. As the result, these ellipsoidal particles, approx. 100 nm long and 50 nm wide can be observed using back-scattered electrons signal in conventional SEM due to chemical contrast. TEM study proved that these particles indeed belong to ω phase. Co-existence of β, ω and α phases was observed. Thin α lamellae were observed along with distorted ω phase particles by TEM

Amplitude-dependent internal friction in AZ31 alloy sheets submitted to accumulative roll bonding

Fine grained magnesium alloy AZ31 sheets were submitted to the accumulative roll bonding (ARB). After ARB, the microstructure of samples was refined, and the sheets exhibited pronounced texture. The amplitudedependent internal friction (ADIF) was measured at room temperature. Microstructure changes as the increased dislocation density, grain size refinement, twins, and texture influenced the ADIF. A significant anisotropy of the properties was observed. Experimental results are discussed on the base of physical mechanisms responsible for internal friction.Дрібнозернисті листи магнієвих сплавів AZ31 були піддані накопичувальному з’єднанню вальцюванням (ARB). Після застосування ARB мікроструктура зразків ставала більш фрагментованою, і в листах спостерігалась яскраво виражена текстура. Амплітудно-залежне внутрішнє тертя (АЗВТ) вимірювали при кімнатній температурі. Зміни мікроструктури, такі як збільшення щільності дислокацій, зменшення розміру зерна, поява двійників та текстури, приводили до змін АЗВТ. Спостерігалась суттєва анізотропія вивчених властивостей. Експериментальні результати обговорюються на базі відомих фізичних механізмів, що відповідають за внутрішнє тертя.Мелкозернистые листы магниевых сплавов AZ31 были подвергнуты накопительному соединению прокаткой (ARB). После применения ARB микроструктура образцов становилась более фрагментированной, и в листах наблюдалась ярко выраженная текстура. Амплитудно-зависимое внутреннее трение (АЗВТ) измеряли при комнатной температуре. Изменения микроструктуры, такие как увеличение плотности дислокаций, уменьшение размера зерна, появление двойников и текстуры, приводили к изменениям АЗВТ. Наблюдалась существенная анизотропия изученных свойств. Экспериментальные результаты обсуждаются на основе известных физических механизмов, отвечающих за внутреннее трение

A parametric simulation method for discrete dislocation dynamics

A new computer simulation method employed in discrete dislocation dynamics is presented. The article summarizes results of an application of the method to elementary interactions among glide dislocations and dipolar dislocation loops. The glide dislocations are represented by parametrically described curves moving in glide planes whereas the dipolar loops are treated as rigid objects. All mutual force interactions are considered in the models. As a consequence, the computational complexity rapidly increases with the number of objects considered. This difficulty is treated by advanced computational techniques such as suitable accurate numerical methods and parallel implementation of the algorithms. Therefore the method is able to simulate particular phenomena of dislocation dynamics which occur in crystalline solids deformed by single slip: generation of glide dislocations from the Frank-Read source, interaction of glide dislocations with obstacles, their encounters in channels of the bands, sweeping of dipolar loops by glide dislocations and a loop clustering