Enhancing Toughness and Impact Strength of Epoxy Resins by Using Hyperbranched Polymers

Toughened epoxy has been widely used in industrial areas such as automotive and electronics. In this study, nanosized hyperbranched polymers (HBPs) as a flexibilizer are synthesized and embedded into epoxy resin to enhance the toughness and flexibility. Two different HBPs, hyperbranched poly(methylacrylate-diethanolamine) (poly(MA-DEA)) and poly(methylacrylate- ethanolamine) (poly(MA-EA)), were prepared and blended with both epoxy and polyetheramine, a curing agent. The molecular size of HBPs was estimated to be 6 ~ 14 nm in diameter. The molecular weight of HBPs ranges from 1500(1.5 K) to 7000(7.0 K) g/mol. In cured epoxy/HBP blends, no phase separations are occurred, indicating that HBPs possess sufficient miscibility with epoxy. The tensile toughness of the blends increased with changing the molecular weight of HBPs without sacrificing tensile strengths. The impact strength of the blends increases stiffly until the loading % of HBPs in the blends reaches 10 wt%. In addition, the experimental studies showed that impact resistance also increased with an increase in molecular weight of HBPs. The obtained impact resistance of the epoxy/HBP blends with 10 wt% was 270% more effective compared to that of cured neat epoxy.

Quantitative Analysis of Phase Separation Using the Lattice Boltzmann Method

Phase separation is widely observed in multiphase systems. In this study, it has been investigated using Shan–Chen lattice Boltzmann method. The adhesion parameter in SC model leads to the desired fluid–fluid phenomenon, which was varied to specify the strength of separation between two phases to present emulsified performance in oil production. In order to describe such behaviors quantitatively, graphical distributions were described with time and were corresponded with a statistical index–Fourier structure factor that is able to predict complex phase separation behaviors, thereby providing a measurement for calculating such random distribution during the process of separation as well as evaluating heterogeneous degrees of the entire domain. The repulsive interactions are specified as low, intermediate, and high values. Phase separations with clear boundaries have been observed and each stage of separation evolvement has been discussed in this study. Magnitudes of structure factors are increased with higher degrees of fluctuations.

Mesoscale phase separation of chromatin in the nucleus

Intact-organism imaging of Drosophila larvae reveals and quantifies chromatin-aqueous phase separation. The chromatin can be organized near the lamina layer of the nuclear envelope, conventionally fill the nucleus, be organized centrally, or as a wetting droplet. These transitions are controlled by changes in nuclear volume and the interaction of chromatin with the lamina (part of the nuclear envelope) at the nuclear periphery. Using a simple polymeric model that includes the key features of chromatin self-attraction and its binding to the lamina, we demonstrate theoretically that it is the competition of these two effects that determines the mode of chromatin distribution. The qualitative trends as well as the composition profiles obtained in our simulations compare well with the observed intact-organism imaging and quantification. Since the simulations contain only a small number of physical variables we can identify the generic mechanisms underlying the changes in the observed phase separations.

Nanoscale phase separations in as-fabricated thick super duplex stainless steels

Nanoscale phase separations, and effects of these, were studied for thick super duplex stainless steel products by atom probe tomography and mechanical testing. Although nanoscale phase separations typically occur during long-time service at intermediate temperatures (300–500° C, our results show that slowly cooled products start to develop Fe and Cr separation and/or precipitation of Cu-rich particles already during fabrication. Copper significantly slowed down the kinetics at the expense of Cu-rich particle precipitation, where the high-copper material subjected to hot isostatic pressing (HIP), with Δt500–400 of 160 s and the low-copper hot-rolled plate with Δt500–400 of 2 s had the same level of Fe and Cr separation. The phase separations resulted in lower toughness and higher hardness of the HIP material than for hot-rolled plate. Therefore, both local cooling rate dependent and alloy composition governed variations of phase separations can be expected in as-fabricated condition.

Intrinsically Disordered Proteins as Regulators of Transient Biological Processes and as Untapped Drug Targets

Intrinsically disordered proteins (IDPs) are critical players in the dynamic control of diverse cellular processes, and provide potential new drug targets because their dysregulation is closely related to many diseases. This review focuses on several medicinal studies that have identified low-molecular-weight inhibitors of IDPs. In addition, clinically relevant liquid–liquid phase separations—which critically involve both intermolecular interactions between IDPs and their posttranslational modification—are analyzed to understand the potential of IDPs as new drug targets.

DEAD-box helicases modulate dicing body formation in Arabidopsis

Eukaryotic cells contain numerous membraneless organelles that are made from liquid droplets of proteins and nucleic acids and that provide spatiotemporal control of various cellular processes. However, the molecular mechanisms underlying the formation and rapid stress-induced alterations of these organelles are relatively uncharacterized. Here, we investigated the roles of DEAD-box helicases in the formation and alteration of membraneless nuclear dicing bodies (D-bodies) in Arabidopsis thaliana. We uncovered that RNA helicase 6 (RH6), RH8, and RH12 are previously unidentified D-body components. These helicases interact with and promote the phase separation of SERRATE, a key component of D-bodies, and drive the formation of D-bodies through liquid-liquid phase separations (LLPSs). The accumulation of these helicases in the nuclei decreases upon Turnip mosaic virus infections, which couples with the decrease of D-bodies. Our results thus reveal the key roles of RH6, RH8, and RH12 in modulating D-body formation via LLPSs.