Features of microstructure formation in the AK4-1 and AK12D aluminum alloys after their joint friction stir processing

Friction stir processing is one of the modern methods of local modification of the surface of aluminum alloys in the solid-phase state, which provides the dispersion of structural components. In heat-hardened aluminum alloys with a matrix type structure, heat treatment following after friction stir processing can lead to abnormal grain growth in the stir zone. However, in alloys with the structure close to microduplex type, a fine-grained structure can be formed after friction stir processing and heat treatment. This work is aimed at evaluating the possibility of increasing the microstructure thermal stability of the AK4-1 (Al–Cu–Mg–Fe–Si–Ni) matrix-type aluminum alloy. For this purpose, AK12D (Al–Si–Cu–Ni–Mg) aluminum alloy with the structure close to microduplex type was locally mixed into the studied alloy by friction stir processing. Subsequent Т6 heat treatment was carried out according to the standard mode for the AK4-1 alloy. Studies showed that the stir zone had an elliptical shape with an onion-ring structure. This structure comprised alternating rings with different amounts and sizes of excess phases. At the same time, in the stir zone center, the width of rings and the average area of excess phases were larger compared to the stir zone periphery, where the width of rings and the average area of particles were smaller. The average area of excess phases in the rings with their higher content was smaller than in the rings with their lower content. This distribution of excess phases leads to the formation of a fine-grained microstructure, where the average size of grains depends on the interparticle distance in the α-Al solid solution

EBSD study of superplastically strained Al-Mg-Li alloy

In this study, electron back scatter diffraction (EBSD) was employed to examine the microstructure evolved during superplastic deformation of advanced Al-Mg-Li alloy. In contrast to the widely-accepted conception of superplasticity, the microstructure was found to be characterized by elongated grains, a notable fraction of low-angle boundaries, and a distinct (though a very weak) crystallographic texture. All these observations suggested a significant activity of intragranular slip

Anabolic activity of leuzea and cranberry meal plant extracts composition

Еhe anabolic properties of a new composition of leuzea and cranberry meal extracts in a ratio of 7:50, containing ecdisten and ursolic acid, respectively, have been investigates on a model of isolated overload of the skeletal muscle of the rats leg by the method of excision. Material and methods. The experiment was conducted on Wistar stock rats of both sexes weighing 220–250 g. At the beginning of the experiment, all animals underwent musculus gastrocnemius tenotomy (m.gastrocnemius), and then the composition has been intragastrically administered for 14 days. At the end of the experiment, the rats were decapitated, blood was taken to determine biochemical parameters (creatine phosphokinase activity, glucose and lactate level) and muscles from both legs were separated to determine the difference between the mass of the musculus soleus (m. soleus) operated on and the mass m.soleus of a non-operated paw. Results and discussion. A dose-dependent anabolic effect was established for the composition of leuzea and cranberry meal extracts. A gender difference was found, which was confirmed by the obtained values of creatine phosphokinase activity and glucose/lactate ratio. Conclusions. The composition of leuzea and cranberry meal extracts exhibits a dose-dependent anabolic effect in males and increase physical endurance in female rats on the model of isolated overload of the skeletal muscle of the leg of rats with tenotomy operation

Superplastic behavior of fine-grained Al-Mg-Li alloy

The superplastic behavior of fine-grained 1420 Al-Mg-Li alloy was investigated using a modern electron microscopy technique based on automatic analysis of electron backscattered diffraction patterns (EBSD analysis

Subclinical markers of liver damage in patients with arterial hypertension and obesity

Aim. To investigate the possibility of preclinical detection of liver damage in patients with hypertension and obesity. Materials and methods. The study included 168 patients with hypertension aged 30 to 60 years. All patients underwent general clinical and laboratory-instrumental examination, including ultrasound of the abdominal organs with Doppler assessment of blood flow and determination of markers such as ALT, AST, TG, lipid profile indicators at inclusion, after a month, three months and nine months. Results. Depending on the presence of obesity, all patients with hypertension were divided into two groups. Obese patients had a statistically significant increase in office blood pressure, FSI, the ratio of TG and LDL-C to HDL-C, a more significant higher average levels of glucose, TG and ALT levels, as well as impaired hepatic blood flow according to ultrasound. Conclusion. Indicators of FSI, ALT/AST ratio, ratio of TG and LDL-С to HDL-C as well as assessment of hepatic blood flow indicators can be used for early diagnosis of nonalcoholic fatty liver disease, as they predict liver steatosis

Serum cytokine signature that discriminates Helicobacter pylori positive and negative juvenile gastroduodenitis

© 2016 Khaiboullina, Abdulkhakov, Khalikova, Safina, Martynova, Davidyuk, Khuzin, Faizullina, Lombardi, Cherepnev and Rizvanov.Gastroduodenitis caused by H. pylori, often acquired in early childhood, is found in about 50% of the adult population. Although H. pylori infections can remain asymptomatic, its virulence factors usually trigger epithelial vacuolization and degeneration, loss of microvilli, disintegration of cytoplasm, and leukocyte accumulation. It is believed that leukocyte infiltration is driven by cytokines produced locally in infected tissue. However, so far little is known about changes in serum cytokines in juvenile patients infected with H. pylori. Serum cytokine profiles were analyzed in 62 juvenile patients diagnosed with gastroduodenitis using the Bio-Plex multiplex assay. H. pylori infection was confirmed in 32 patients, while 30 patients were H. pylori-free. Cytokines CXCL5 and CXCL6, potent neutrophil chemoattractants, were upregulated in all patients diagnosed with gastroduodenitis. Serum levels of IL8, a prototype neutrophil attractant, remained unchanged in subjects with gastroduodenitis relative to controls. Therefore, our data suggest that CXCL5 and CXCL6 play a role in directing neutrophil trafficking into inflamed gastroduodenal tissue. In addition, the CCL25/GM-CSF ratio differed significantly between H. pylori-positive and -negative juveniles. Further, study is needed to evaluate the role of CCL25 and GM-CSF in the pathogenesis of the different etiologies of gastroduodenitis

Timing of AR CrB eclipses

AR CrB is a short-period low-mass eclipsing binary. We conducted photometric observations of the system in 2013, 2014, 2016, 2017, and obtained times of its light curves minima. The timing of eclipses (our times of minima combined with data from the literature) shows that the orbital period of AR CrB could possess periodical variations that can be explained by the gravitational influence of a third companion in a highly eccentric orbit around the central binary

Light equation on eclipsing binary CV Boo

Короткопериодическая затменная двойная звезда CV Boo изучена методом светового уравнения. Были использованы данные о моментах минимумов из литературы и из наших наблюдений в мае июле 2014 г. Была найдена периодическая вариация орбитального периода системы с периодом ≈ 75 дней. Эта вариация может быть объяснена гравитационным воздействием третьего тела с массой ≈ 0.4 M⊙ на вытянутой орбите с эксцентриситетом e ≈ 0.9. Также обсуждается возможность изменения орбитального периода на больших шкалах времени. Предлагаемое третье тело находится близко к хаотической зоне вокруг центральной двойной, поэтому оно может быть интересно для изучения его динамической эволюции.A short period eclipsing binary star CV Boo is tested for the possible existence of new bodies in the system with a help of the light equation method. We use data about moments of minima from the literature and our observations during May—July 2014. A periodical variation of CV Boo’s orbital period is found, the variation’s period is ≈ 75 days. This variation can be explained by the gravitational influence of a third star with a mass ≈ 0.4M⊙ in an eccentric orbit with e ≈ 0.9. A possibility for orbital period changes in long time scales is discussed. The suggested tertiary companion is near the chaotic zone around the central binary, so it is an interesting example to test its dynamical evolution

Experimental research of heat exchanger power and heat transfer coefficients, that consists of four series-connected smooth tubes

Abstract: This article talks about executed researches of a new design of the heat exchanger, consisting of four series-connected smooth tubes, with diameter. According to the results of an experiment conducted under conditions of natural convection, the capacity and heat transfer coefficients of the heat exchanger were and In the case of forced convection with air speed of power of the heat exchanger was increased up to and transfer coefficients were increased to 15 W/(м2К).Выполнены исследования новой конструкции теплообменника, состоящего из четырех последовательно соединенных гладких труб, диаметром 0,057 м. По результатам эксперимента, проведённого в условиях естественной конвекции, мощность теплообменника и коэффициенты теплоотдачи оказались равными соответственно 452 Вт и 11,6 Вт/(м2•К). В случае вынужденной конвекции со скоростью движения воздуха 1,5 м/с мощность теплообменника увеличивается до 754 Вт, а коэффициенты теплоотдачи – до 15 Вт/(м2К)