Formation of Nanostructure during Replication of a Hierarchical Plant Surface

Plant and animal surfaces have become a model for preparing special synthetic surfaces with low wettability, reflectivity, or antibacterial properties. Processes that lead to the creation of replicas of natural character use two-step imprinting methods. This article describes a technique of synthetic polymer surface preparation by the process of two-stage imprinting. The laboratory-prepared structure copies the original natural pattern at the micrometer and sub-micrometer levels, supplemented by a new substructure. The new substructure identified by the scanning electron microscope is created at the nanometer level during the technological process. The nanostructure is formed only under the conditions that a hierarchical structure forms the surface of the natural replicated pattern, the replication mold is from a soft elastomeric material, and the material for producing the synthetic surface is a polymer capable of crystallizing. A new nanometer substructure formation occurs when the polymer cools to standard laboratory temperature and atmospheric pressure.

SUBSTRUCTURE FORMATION IN TIDAL STREAMS OF GALACTIC MINOR MERGERS

In this work, we explore the idea that substructures like stellar clusters could be formed from the tidal stream produced in galactic minor mergers. We use N -body and SPH simulations of satellite galaxies interacting with a larger galaxy. We study the distribution of mass in streams to identify overdensity regions in which a substructure could be formed. We find that without gas, no substructure forms as none of the overdensities shows a definite morphology nor dynamical stability. Including gas we find that several clumps appear and prove to be real long standing physical structures (t ≥ 1 Gyr). We analyze the orbits, ages and masses of these structures, finding their correspondence with the halo subsystems. We conclude that it is possible to form cluster-like structures from the material in tidal streams and find evidence in favour of the presence of dark matter in these systems.

The possible hierarchical scales of observed clumps in high-redshift disc galaxies

ABSTRACTGiant clumps on ∼kpc scales and with masses of $10^8\rm {-}10^9 \, \mathrm{M_{\odot }}$ are ubiquitous in observed high-redshift disc galaxies. Recent simulations and observations with high spatial resolution indicate the existence of substructure within these clumps. We perform high-resolution simulations of a massive galaxy to study the substructure formation within the framework of gravitational disc instability. We focus on an isolated and pure gas disc with an isothermal equation of state with T = 104 K that allows capturing the effects of self-gravity and hydrodynamics robustly. The main mass of the galaxy resides in rotationally supported clumps which grow by merging to a maximum clump mass of $10^8 \, \mathrm{M_{\odot }}$ with diameter ∼120 pc for the dense gas. They group to clump clusters (CCs) within relatively short times ($\ll 50 \, \mathrm{Myr}$), which are present over the whole simulation time. We identify several mass and size scales on which the clusters appear as single objects at the corresponding observational resolution between ${\sim } 10^8 \,\rm{and}\, 10^9 \, \mathrm{M_{\odot }}$. Most of the clusters emerge as dense groups and for larger beams they are more likely to be open structures represented by a single object. In the high-resolution runs higher densities can be reached, and the initial structures can collapse further and fragment to many clumps smaller than the initial Toomre length. In our low-resolution runs, the clumps directly form on larger scales 0.3–1 kpc with $10^8\rm {-}10^9 \, \mathrm{M_{\odot }}$. Here, the artificial pressure floor which is typically used to prevent spurious fragmentation strongly influences the initial formation of clumps and their properties at very low densities.

Microstructure of ionic liquid (EAN)-rich and oil-rich microemulsions studied by SANS

Role of EAN substructure formation in both oil-in-EAN and EAN-in-oil microemulsions revealed by SANS.