Surface Morphology Investigations of Nanocrystalline R2Fe14B (R = Y, Nd, Gd, Er) by Atomic Force Microscopy

The study was aimed at microstructure investigations of melt-spun rare-earth intermetallic compounds using atomic force microscopy. Surface morphology of R2Fe14B (R = Y, Nd, Gd, Er) was studied with nanometric resolution. Grain structure features were discovered depending on the rare-earth element composition and quenching regime. Grain size dependence on rare earth elements' composition decreased with the metal's serial number and atomic weight. Wherein structural size dependence on quenching wheel speed had non-linear character: increase the speed from 20 to 30 m/s led to 3 times decrease of the grain size and significant surface roughness reduction.

Size Distributions of Bluish and Reddish Small Main-belt Asteroids Obtained by Subaru/Hyper Suprime-Cam*

We performed a wide-field survey observation of small asteroids using the Hyper Suprime-Cam installed on the 8.2 m Subaru Telescope. We detected more than 3000 main-belt asteroids with a detection limit of 24.2 mag in the r-band, which were classified into two groups (bluish C-like and reddish S-like) by the g–r color of each asteroid and obtained size distributions of each group. We found that the shapes of the size distributions of asteroids with C-like and S-like colors agree with each other in the size range of 0.4–5 km in diameter. Assuming the asteroid population in this size range is under collision equilibrium, our results indicate that compositional difference hardly affects the size dependence of impact strength, at least for the size range between several hundred meters and several kilometers. This size range corresponds to the size range of “spin barrier,” an upper limit observed in the rotation rate distribution. Our results are consistent with the view that most asteroids in this size range have a rubble-pile structure.

Functionalizing lipid sponge droplets with DNA

Nucleic acids are among the most versatile molecules for the construction of biomimetic systems because they can serve as information carriers and programmable construction materials. How nucleic acids interact with membranous coacervate compartments such as lipid sponge droplets is not known. Here we systematically characterize the potential of DNA to functionalize lipid sponge droplets and demonstrate a strong size dependence for sequestration into the sponge phase. Double stranded DNA molecules of more than 300 bp are excluded and form a corona on the surface of droplets they are targeted to. Shorter DNA molecules partition efficiently into the lipid sponge phase and can direct DNA-templated reactions to droplets. We demonstrate repeated capture and release of labeled DNA strands by dynamic hybridization and strand displacement reactions that occur inside droplets. Our system opens new opportunities for DNA-encoded functions in lipid sponge droplets such as cargo control and signaling.

An analytical and numerical study of capillary menisci

В работе рассмотрены математические модели осесимметричных капиллярных менисков — лежащая и висящая капли, развернутый мениск, учитывающие размерную зависимость поверхностного натяжения. Доказаны теоремы существования и единственности решений задач, описывающих равновесные поверхности менисков. Разработаны и протестированы эффективные численные методы, предназначенные для приближенного расчета профилей менисков. На языке «Wolfram Language» написана компьютерная программа, с помощью которой проведены масштабные вычислительные эксперименты по выявлению степени и характера влияния параметров моделей на равновесную форму каждого из рассматриваемых менисков In the current paper we consider the mathematical models of axisymmetric capillary menisci — sessile and pendant drops, rolled out meniscus, taking into account the size dependence of surface tension. Existence and uniqueness theorems for solutions of problems describing equilibrium meniscus surfaces are proved. Effective numerical methods have been developed and tested for the approximate calculation of meniscus profiles. A computer program is written in the Wolfram Language, with the help of which large-scale computational experiments were carried out to reveal the degree and nature of the influence of the model parameters on the equilibrium shape of each type of menisci.