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납본여부: 미납본

Supercomputing and Beyond

비매품/무

Strengthening effect of single-atomic-layer graphene in metal–graphene nanolayered composites

Graphene is a single-atomic-layer material with excellent mechanical properties and has the potential to enhance the strength of composites. Its two-dimensional geometry, high intrinsic strength and modulus can effectively constrain dislocation motion, resulting in the significant strengthening of metals. Here we demonstrate a new material design in the form of a nanolayered composite consisting of alternating layers of metal (copper or nickel) and monolayer graphene that has ultra-high strengths of 1.5 and 4.0 GPa for copper–graphene with 70-nm repeat layer spacing and nickel–graphene with 100-nm repeat layer spacing, respectively. The ultra-high strengths of these metal–graphene nanolayered structures indicate the effectiveness of graphene in blocking dislocation propagation across the metal–graphene interface. Ex situ and in situ transmission electron microscopy compression tests and molecular dynamics simulations confirm a build-up of dislocations at the graphene interface

Molecular Behavior of Biopolymers in Nano/Microstructures

funder : 과학기술부agency : 한국IBMIBM R&D 과제를 통한 나노/마이크로구조에서의 생체 고분자들의 분자 거동 연구를 수행하여 나노/마이크로 수준의 작은 시스템 내에서의 생체고분자의 거동을 연구 할 수 있는 분자동역학 전사 모사 및 Dissipative Particle 동역학 전산 모사 프로그램을 개발하고 이를 IBM 슈퍼컴퓨터에 맞게 최적화 및 병렬화를 수행하여 거대 규모의 전산 모사를 통해 채널 속에서의 생체 고분자의 거동을 연구하였다

Theoretical study on the stability of insulin within poly-isobutyl cyanoacrylate (PIBCA) nanocapsule

To study the physical stability of insulin in drug delivery particles, we developed a coarse-grained (CG) model for insulin based on dissipative particle dynamics (DPD). Three insulin modelling schemes were considered: each amino acid as a bead (IM1), each amino acid being separated into one to three beads (IM2), and adding secondary structural information of insulin to IM2 (IM3). The best possible bead-bead interaction parameters were obtained from Hildebrand and Hansen solubility parameters by performing the constant-temperature DPD simulation with insulin models in 20% acetic acid solution. IM3 showed good results in terms of RMSF, RMSD and A1B30 distance compared to those of all-atom models from the literature. Then, the IM3 model was considered in an oil-filled poly (isobutyl cyanoacrylate) (PIBCA) nanocapsule. Two crucial factors were found that mainly influence the stability of insulin in oil: the PIBCA shell thickness and the amount of ethanol in the oil droplet. An appropriate PIBCA shell thickness is necessary to block the interaction between insulin and water outside, and ethanol could stabilise insulin with its good affinity for both insulin and oil

채널 유동내에서의 단일 고분자의 거동

The possibility of an inducement of fluid flow by a geometrical channel structure and the effects of the contraction ratio on the dynamics of a single Dissipative Particle Dynamics (DPD) chain in static channels of linearly varying cross-sectional area are investigated by using a dissipative particle dynamics simulation. Frozen DPD wall particles supporting these static channels interact with the fluid DPD particles such as DPD solvent particles and a DPD chain in the fluid domain. The density profiles, the velocity profiles, and the probability distribution of the DPD solvent particles and those of a single DPD chain are calculated for several contraction ratios which are defined as the ratio of the side lengths of two squares at the leftmost and the rightmost simulation domain. A static channel structure of linearly varying cross-sectional area induces a fluid flow, which moves from the region of small cross-section of a channel to the region of large cross-section of a channel

A strong linear correlation between the surface charge density on Ag nanoparticles and the amount of propylene adsorbed

The partial positive charge density of the surface of Ag nanoparticles was modulated by an electron acceptor, 7,7,8,8-tetracyanoquinodimethane (TCNQ), to improve their reversible interactions with olefins such as propylene, but not with paraffin. The silver binding energy in Ag NPs, representing the surface charge density, exhibited a maximum at a TCNQ concentration of 0.05 mol% (0.26 molecules per nm2). The amount of propylene adsorbed on the surface of the Ag NPs was strongly correlated with the silver binding energy with a high correlation factor of 0.97. In addition propylenes were found to be adsorbed on the TCNQ-uncovered, vacant sites of Ag NPs according to quantum mechanical calculation. It was therefore concluded that the enhanced interaction between the surface-modulated Ag NPs and propylene is attributable to the high separation performance for olefin뻪araffin mixtures based on selective facilitated olefin transport