Microstructure evolution in a Cu-Cr-Zr alloy during warm intense plastic straining

The effect of equal channel angular pressing at a temperature of 200°C to a total strain of 12 on microstructure evolution and mechanical properties of a Cu-0.87wt.%Cr- 0.06wt.%Zr was investigated. New ultrafine grains resulted from gradual increase in the misorientations of strain-induced low-angle boundaries with increasing number of passes. Therefore, the development of ultrafine grains is considered as a kind of dynamic recrystallization. The equal channel angular pressing to a total strain of 12 resulted in the formation of almost equiaxed ultrafine grained structure with an average grain size of 0.5 Tm and 0.7 Tm in the solution treated and aged samples, respectively. At the same time, the fraction of ultrafine grains comprises 0.77 in the solution treated samples and 0.72 in the aged samples. Significant grain refinement led to the remarkable increase of the ultimate tensile strength up to 550 MP

Electronic structure study of YNbTiO6_6 vs. CaNb2_2O6_6 with U, Pu and minor actinide substitutions using compound-tunable embedding potential method

The compound-tunable embedding potential (CTEP) method is applied to study actinide substitutions in the niobate crystals YNbTiO$_6$ and CaNb$_2$O$_6$. Two one-center clusters centered on Ca and Y are built and 20 substitutions of Ca and Y with U, Np, Pu, Am, and Cm in four different oxidation states were made for each cluster. Geometry relaxation is performed for each resulting structure, and electronic properties are analyzed by evaluating the spin density distribution and X-ray emission spectra chemical shifts. Though the studied embedded clusters with actinides having the same oxidation state are found in general to yield similar local structure distortions, for Am and Cm in high "starting" oxidation states the electron transfer from the environment was found, resulting in decrease of their oxidation states, while for "starting" U$^{\rm III}$ state the electron transfer goes in the opposite direction, resulting in increase of its oxidation state to U$^{\rm IV}$. The U substitutions are additionally studied with the use of multi-center models, which can provide both more structural and electronic relaxation and also include charge-compensating vacancies. For "starting" U$^{\rm VI}$ case, the decrease in oxidation state similar to that of Am$^{\rm VI}$ and Cm$^{\rm VI}$ in one-center clusters is observed in our calculations but in a different way. Since the really synthesized YNbTiO$_6$ structures can not be considered as perfect (periodic) crystals because the Nb and Ti atoms are statistically distributed within them occupying the same Wyckoff positions, different Ti $\leftrightarrow$ Nb substitutions are studied and corresponding structural changes are estimated

Siberian Arctic black carbon sources constrained by model and observation

Black carbon (BC) in haze and deposited on snow and ice can have strong effects on the radiative balance of the Arctic. There is a geographic bias in Arctic BC studies toward the Atlantic sector, with lack of observational constraints for the extensive Russian Siberian Arctic, spanning nearly half of the circum-Arctic. Here, 2 y of observations at Tiksi (East Siberian Arctic) establish a strong seasonality in both BC concentrations (8 ng⋅m−3 to 302 ng⋅m−3) and dual-isotope–constrained sources (19 to 73% contribution from biomass burning). Comparisons between observations and a dispersion model, coupled to an anthropogenic emissions inventory and a fire emissions inventory, give mixed results. In the European Arctic, this model has proven to simulate BC concentrations and source contributions well. However, the model is less successful in reproducing BC concentrations and sources for the Russian Arctic. Using a Bayesian approach, we show that, in contrast to earlier studies, contributions from gas flaring (6%), power plants (9%), and open fires (12%) are relatively small, with the major sources instead being domestic (35%) and transport (38%). The observation-based evaluation of reported emissions identifies errors in spatial allocation of BC sources in the inventory and highlights the importance of improving emission distribution and source attribution, to develop reliable mitigation strategies for efficient reduction of BC impact on the Russian Arctic, one of the fastest-warming regions on Earth

Forecasting the development of mechanical engineering using the system dynamics method

At modern conditions of world economy tendencies, the connections between subjects of economy are becoming more difficult and closer. In particular, if in the past were spread hard forms of private ownership of enterprises at present-day world is going conversion to more flexible and mobile composition of subjects' activities. Computer simulation modeling is giving the best results at the areas were the participants of social and economic activities are spending significant efforts and sufficiently much time for visuality playing and analysis of possible variants of the development of the events. The more difficult is the situation the more objects, factors, and possible variants of events' progress is necessary to play in different combinations between together and bigger effect possible to expect from application of simulation model for analyzing of the situation and for searching and making optimized decisions. The application of system dynamics method allows executing forecasting of economic agents including the sectors of economy. © 2020 American Institute of Physics Inc.. All rights reserved

Source apportionment of circum-Arctic atmospheric black carbon from isotopes and modeling

Black carbon (BC) contributes to Arctic climate warming, yet source attributions are inaccurate due to lacking observational constraints and uncertainties in emission inventories. Year-round, isotope-constrained observations reveal strong seasonal variations in BC sources with a consistent and synchronous pattern at all Arctic sites. These sources were dominated by emissions from fossil fuel combustion in the winter and by biomass burning in the summer. The annual mean source of BC to the circum-Arctic was 39 ± 10% from biomass burning. Comparison of transport-model predictions with the observations showed good agreement for BC concentrations, with larger discrepancies for (fossil/biomass burning) sources. The accuracy of simulated BC concentration, but not of origin, points to misallocations of emissions in the emission inventories. The consistency in seasonal source contributions of BC throughout the Arctic provides strong justification for targeted emission reductions to limit the impact of BC on climate warming in the Arctic and beyond

Non-invasive optical method for evaluating the oxygen status in breast neoplasms

The paper presents the results from a study of the breast oxygen status by diffuse optical tomography (DOT). Detection of breast tissue at wavelengths of 684, 794, and 850 nm could provide information on the distribution of basic tissue chromophores: oxygenized and deoxygenized hemoglobin. Normal breast tissue was characterized by the even distribution of these compounds and stabilization of their level. In breast cancer, the distribution of oxy- and deoxyhemoglobin was noted for uneven distribution and blood oxygen saturation was lower in the projection of a tumor nodule. The blood oxygen saturation data obtained by DOT demonstrate physiological differ- ences between normal and tumor tissues in different tumor areas

Инфаркт миокарда в послеродовом периоде

The study objective Is to present a clinical observation, describe the diagnostics and treatment of acute transmural myocardial infarction in a patient on the 8th day after childbirthMaterial and methods A 31-year-old patient was hospitalized 3 hours after the onset of the disease on the 8th day after urgent spontaneous delivery at 38-39 weeks of gestation with a clinic of acute myocardial infarction in the intensive care unit. Based on the data of anamnesis, complaints, physical examination, results of instrumental and laboratory examination, the following clinical diagnosis was made: ischemic heart disease: acute transmural myocardial infarction of the anterior wall, septum and apex of the left ventricle; atherosclerosis of the aorta and coronary arteries. On an emergency basis, the patient underwent coronary angiography, pronounced atherosclerotic changes in the coronary arteries were revealed: acute occlusion of the anterior interventricular artery in the middle third, stenosis of the diagonal branch up to 70% in the orifice, stenosis of the circumflex branch up to 70% in the middle third, extended stenosis up to 79% in the middle third of the right coronary artery.Results The patient underwent percutaneous coronary intervention (pci) on a symptom-dependent artery: mechanical recanalization and stenting of the anterior descending artery (ada) by a drug-eluting stent.Conclusion An increase in the incidence of acute coronary syndrome in pregnant women and postpartum women requires the development of an algorithm for additional examination of late reproductive age patients at the stage of pregnancy planning, in case of identification of possible risk factors for the development of cardiovascular diseases — observation of a cardiologist during pregnancy and in the postpartum period.Цель Представить клиническое наблюдение, описать диагностику и лечение острого трансмурального инфаркта миокарда у пациентки на 8-е сутки после родов.Материал и методы Пациентка 31 года, госпитализирована через 3 часа после начала заболевания на 8-е сутки после срочных самопроизвольных родов в 38–39 недель беременности с клиникой острого инфаркта миокарда в палату реанимации и интенсивной терапии. На основании данных анамнеза, жалоб, объективного осмотра, результатов инструментального и лабораторного обследования поставлен клинический диагноз: «Ишемическая болезнь сердца: острый трансмуральный инфаркт миокарда передней стенки, перегородки и верхушки левого желудочка; атеросклероз аорты и коронарных артерий». В экстренном порядке пациентке выполнена коронарография, и выявлены выраженные атеросклеротические изменения коронарных артерий: острая окклюзия передней межжелудочковой ветви в средней трети, стеноз диагональной ветви — до 70% в устье, cтеноз огибающей ветви — до 70% в средней трети, протяженный стеноз — до 79% в средней трети правой коронарной артерии.Результаты Больной было выполнено чрескожное коронарное вмешательство на симптом-зависимой артерии: механическая реканализация и стентирование передней нисходящей артерии стентом с лекарственным покрытием.Заключение Увеличение частоты острого коронарного синдрома у беременных и родильниц требует разработки алгоритма дополнительного обследования пациенток позднего репродуктивного возраста на этапе планирования беременности, а при выявлении факторов риска развития сердечно-сосудистых заболеваний — наблюдения кардиолога во время беременности и в послеродовом периоде

Extensive release of methane from Arctic seabed west of Svalbard during summer 2014 does not influence the atmosphere

© 2016. American Geophysical Union. All Rights Reserved. We find that summer methane (CH4) release from seabed sediments west of Svalbard substantially increases CH4 concentrations in the ocean but has limited influence on the atmospheric CH4 levels. Our conclusion stems from complementary measurements at the seafloor, in the ocean, and in the atmosphere from land-based, ship and aircraft platforms during a summer campaign in 2014. We detected high concentrations of dissolved CH4 in the ocean above the seafloor with a sharp decrease above the pycnocline. Model approaches taking potential CH4 emissions from both dissolved and bubble-released CH4 from a larger region into account reveal a maximum flux compatible with the observed atmospheric CH4 mixing ratios of 2.4-3.8 nmol m-2 s-1. This is too low to have an impact on the atmospheric summer CH4 budget in the year 2014. Long-term ocean observatories may shed light on the complex variations of Arctic CH4 cycles throughout the year.The project MOCA- Methane Emissions from the Arctic OCean to the Atmosphere: Present and Future Climate Effects is funded by the Research Council of Norway, grant no.225814 CAGE – Centre for Arctic Gas Hydrate, Environment and Climate research work was supported by the Research Council of Norway through its Centres of Excellence funding scheme grant no. 223259. Nordic Center of Excellence eSTICC (eScience Tool for Investigating Climate Change in northern high latitudes) funded by Nordforsk, grant no. 57001