Studying microstructure of sintered magnets Co-25% Sm

Metallographic study of sintered rare-earth Co- 25% Sm magnets microstructure of KS-25 brand was carried out by scanning electron force microscopy (EDS-analysis). A dendritic structure with three phases was found: branches of dendrites are SmCo5; interdendritic space is a mixture of two phases SmCo5 and Sm2Co17. Crystals of 1-5 μm of Zr5Co3FeSm compound and inclusions of Sm2O3 samarium of a globular form of 2-10 μm in size were founded also in the microstructure. Study of the domain structure on surfaces perpendicular to magnetization axis by magnetic force microscopy (MFM) showed presence of strong magnetocrystalline anisotropy. Comparison of magnetic images with electron microscopic images of surface made it possible to conclude that SmCo5 dendrites correspond to large domains ∼ 30-50 μm in size and the interdendritic space consisting of a mixture of two phases SmCo5 and Sm2Co17 correspond to a domain structure in labyrinth form with a size of ∼ 3-5 μm. © 2019 Published under licence by IOP Publishing Ltd.Government Council on Grants, Russian Federation: № 02.Authors are grateful for the support of experimental works by Act 211 Government Russian Federation, contract № 02.A03.21.0006

Магнитная структура спеченных магнитов Со–25%Sm после электроэрозионной обработки

Scanning electron microscopy and magnetic force microscopy were used to conduct the metallographic study of the surface microstructure of KS25 grade Co–25%Sm sintered rare-earth magnets after Electrical Discharge Machining (EDM). The chemical composition of the studied samples: Sm – 25 wt.%; Fe – 18 wt.%; Cu – 5 wt.%; Zr – 3 wt.%; Co – the rest. One of the sample surfaces was subjected to EDM in various ways with changes in such EDM parameters as the straight-line processing speed and offset. The microstructure of magnets contains four coexisting phases: SmCo5, Sm2Co17, Zr5Co3FeSm and Sm2O3. The grain size is 10–50 μm. Crystals of the Zr5Co3FeSm intermetallic compound are 1–5 μm in size, and globular inclusions of Sm2O3 samarium oxide are 2–10 μm. EDM affected the thickness and chemical composition of the defective layer. In general, the chemical composition varies slightly in the direction from the defective layer inward the sample: the content of Sm, Cu, O, and Zr decreases; the content of Fe and Co increases. At a distance of 500 μm from the defective layer inwards the sample, the grain size increases by 40–50 %, while the porosity decreases. At the same time, the size of Sm2O3 oxides slightly increases. The study of the magnetic structure on surfaces perpendicular to the axis of magnetization by means of magnetic force microscopy revealed the presence of a complex domain structure of grains in the form of a labyrinth with a domain size of ~3÷5 μm. Separate singledomain grains ~30÷50 μm in size were also found. Due to the material heating and oxidation, EDM promotes the domain structure of grains appearing in the form of a labyrinth instead of single-domain grains, and the SmCo5 → Sm2Co17 phase transition, which causes a decrease in coercive force.Средствами сканирующей электронной микроскопии и магнитной силовой микроскопии проведено металлографическое изучение микроструктуры поверхности спеченных редкоземельных магнитов Со–25%Sm марки КС25 после электроэрозионной обработки (ЭЭО). Химический состав исследуемых образцов, мас.%: Sm – 25, Fe – 18, Cu – 5, Zr – 3, Co – остальное. Одна из поверхностей образца была подвергнута электроэрозионной обработке различными способами при изменении таких параметров ЭЭО, как скорость обработки по прямой линии и офсет. В микроструктуре магнитов представлены 4 сосуществующие фазы: SmCo5, Sm2Co17, Zr5Co3FeSm и Sm2O3. Размер зерна составляет 10–50 мкм. Кристаллы интерметаллического соединения Zr5Co3FeSm имеют размер 1–5 мкм, включения оксида самария Sm2O3 глобулярной формы были величиной 2–10 мкм. Способ ЭЭО оказал влияние на толщину и химический состав дефектного слоя. В целом химический состав при удалении от дефектного слоя в глубь образца изменяется незначительно: содержание Sm, Cu, О и Zr снижается, а Fe и Со – повышается. Размер зерна на глубине 500 мкм от дефектного слоя увеличивается на 40–50 %, а пористость, наоборот, уменьшается; размер оксидов Sm2O3 при этом незначительно возрастает. Исследование средствами магнитной силовой микроскопии магнитной структуры на поверхностях, перпендикулярных оси намагничивания, показало наличие сложной доменной структуры зерен в виде лабиринта с размером домена ~3÷5 мкм. Обнаружены также отдельные однодоменные зерна размером ~30÷50 мкм. Электроэрозионная обработка из-за нагрева и окисления материала способствует возникновению доменной структуры зерен в виде лабиринта вместо однодоменных зерен, а также фазовому переходу SmCo5 → Sm2Co17, что вызывает уменьшение коэрцитивной силы

Site-Specifically Labeled Immunoconjugates for Molecular Imaging—Part 1: Cysteine Residues and Glycans

Due to their remarkable selectivity and specificity for cancer biomarkers, immunoconjugates have emerged as extremely promising vectors for the delivery of diagnostic radioisotopes and fluorophores to malignant tissues. Paradoxically, however, these tools for precision medicine are synthesized in a remarkably imprecise way. Indeed, the vast majority of immunoconjugates are created via the random conjugation of bifunctional probes (e.g., DOTA-NCS) to amino acids within the antibody (e.g., lysines). Yet antibodies have multiple copies of these residues throughout their macromolecular structure, making control over the location of the conjugation reaction impossible. This lack of site specificity can lead to the formation of poorly defined, heterogeneous immunoconjugates with suboptimal in vivo behavior. Over the past decade, interest in the synthesis and development of site-specifically labeled immunoconjugates—both antibody-drug conjugates as well as constructs for in vivo imaging—has increased dramatically, and a number of reports have suggested that these better defined, more homogeneous constructs exhibit improved performance in vivo compared to their randomly modified cousins. In this two-part review, we seek to provide an overview of the various methods that have been developed to create site-specifically modified immunoconjugates for positron emission tomography, single photon emission computed tomography, and fluorescence imaging. We will begin with an introduction to the structure of antibodies and antibody fragments. This is followed by the core of the work: sections detailing the four different approaches to site-specific modification strategies based on cysteine residues, glycans, peptide tags, and unnatural amino acids. These discussions will be divided into two installments: cysteine residues and glycans will be detailed in Part 1 of the review, while peptide tags and unnatural amino acids will be addressed in Part 2. Ultimately, we sincerely hope that this review fosters interest and enthusiasm for site-specific immunoconjugates within the nuclear medicine and molecular imaging communities

Measurement of large diameters by indirect methods. Measurement tools development prospects

Слинкин Сергей Александрович, ведущий инженер ОАО «Научно-исследовательский институт технологии, контроля и диагностики железнодорожного транспорта» (ОАО «НИИТКД») (г. Омск); [email protected]. S.A. Slinkin, Scientific and Research Institute of Technology, Control and Diagnosis of Railway Transport, Omsk, Russian Federati in, [email protected]Рассматривается один из косвенных методов измерения больших диаметров на примере колеса колесной пары. Предлагается способ увеличения чувствительности преобразователя и проводится сравнительный анализ нескольких методов. In the article one of indirect methods of large diameters measuring for the example of wheelset is considered. A method of increasing the sensitivity of the transducer is provided and a comparative analysis of the both methods was done