Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Fast parallel algorithms for short-range molecular dynamics

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

“Unpaired Image-to-Image Translation using Cycle-Consistent Adversarial Networks”の学習報告

Since the discovery of mechanically exfoliated graphene in 2004, research on ultrathin two-dimensional (2D) nanomaterials has grown exponentially in the fields of condensed matter physics, material science, chemistry, and nanotechnology. Highlighting their compelling physical, chemical, electronic, and optical properties, as well as their various potential applications, in this Review, we summarize the state-of-art progress on the ultrathin 2D nanomaterials with a particular emphasis on their recent advances. First, we introduce the unique advances on ultrathin 2D nanomaterials, followed by the description of their composition and crystal structures. The assortments of their synthetic methods are then summarized, including insights on their advantages and limitations, alongside some recommendations on suitable characterization techniques. We also discuss in detail the utilization of these ultrathin 2D nanomaterials for wide ranges of potential applications among the electronics/optoelectronics, electrocat...

Recent Advances in Ultrathin Two-Dimensional Nanomaterials

BiFeO3 is perhaps the only material that is both magnetic and a strong ferroelectric at room temperature. As a result, it has had an impact on the field of multiferroics that is comparable to that of yttrium barium copper oxide (YBCO) on superconductors, with hundreds of publications devoted to it in the past few years. In this Review, we try to summarize both the basic physics and unresolved aspects of BiFeO3 (which are still being discovered with several new phase transitions reported in the past few months) and device applications, which center on spintronics and memory devices that can be addressed both electrically and magnetically.

Physics and Applications of Bismuth Ferrite

Developing cost-effective, highly catalytic active, and stable electrocatalysts in alkaline electrolytes is important for the development of highly efficient anion-exchange membrane water electrolysis (AEMWE). To this end, metal oxides/hydroxides have attracted wide research interest for efficient electrocatalysts in water splitting owing to their abundance and tunable electronic properties. It is very challenging to achieve an efficient overall catalytic performance based on single metal oxide/hydroxide-based electrocatalysts due to low charge mobilities and limited stability. This review is mainly focused on the advanced strategies to synthesize the multicomponent metal oxide/hydroxide-based materials that include nanostructure engineering, heterointerface engineering, single-atom catalysts, and chemical modification. The state of the art of metal oxide/hydroxide-based heterostructures with various architectures is extensively discussed. Finally, this review provides the fundamental challenges and perspectives regarding the potential future direction of multicomponent metal oxide/hydroxide-based electrocatalysts.

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Multicomponent Metal Oxide- and Metal Hydroxide-Based Electrocatalysts for Alkaline Water Splitting

We present TiO2 nanohelix gas sensors with top-and-bottom electrodes configuration fabricated by oblique angle deposition (OAD) that is very simple, easy, and compatible with conventional microfabrication processes. The combination of large surface-to-volume ratio, extremely small size (~ 22 nm) with near single crystallinity of TiO2 nanohelices, together with the top-and-bottom electrodes configuration results in a huge enhancement in gas sensing performances including ~10 times higher sensitivity, ~5 times lower detection limit, and much faster response time than the conventional thin film device. By employing this simple, cheap, and easy method, e-nose, consisting of each sensor devices with various nanostructures and metal-oxides, can be realized, having the large freedom of tuning the sensitivity of each device.

P2.7.9 TiO2 Nanohelix Gas Sensors with Enhanced Performance and Potential Application as a Building Block of Electronic Noses

Microstructural Characterization and Thermodynamical Study of In-Situ Phase Formation During Spark Plasma Sintering of Tib2-20%Aln-5%Gr

This work investigates the relationship between atomic arrangement and luminescence properties in a high-quality alpha-Ga2O3 thin film grown on an Al2O3 single-crystal membrane. The strain induced by merging domain boundaries shows more significant variability in annular darkfield images even though there is no additional gallium concentration confirmed. The bandgap energy of alpha-Ga2O3 is estimated to be 5.56 eV from the CL measurement in a transmission electron microscope. A peak at 320 nm was observed within the domain, while the domain boundary showed spectrum peaks with 380–480 nm. The anti-phase domain (APD) is formed by the instabilities of Al–O bonding templates provided by the Al2O3 substrate. The APD boundary gives a characteristic wavelength of 350 nm, which is the result of the merging boundary of in-phase and anti-phase domains.

/pdf/luminescence-properties-related-anti-phase-domain-of-alpha-2um90vt5.pdf

Luminescence properties related anti-phase domain of alpha-Ga2O3

The effects of photowashing treatment on the electrical properties of an AlGaN/GaN heterostructure field-effect transistor were studied by observing changes in atomic composition and band bending at the surface of AlGaN through synchrotron radiation photoemission spectroscopy. The surface treatment produced group-III oxides on the surface of AlGaN, leaving N vacancies behind. Both the gate leakage current (IGD) and drain current (IDS) simultaneously decreased after the treatment. The decrease of IGD was due to a delay in movement of the electrons, namely, trapping and detrapping. The trapped electrons reduced the effective channel thickness, and led to the reduction of IDS.

/pdf/effects-of-photowashing-treatment-on-electrical-properties-uiradih6kj.pdf

Ho Won Jang

Papers

Multicomponent Metal Oxide- and Metal Hydroxide-Based Electrocatalysts for Alkaline Water Splitting

P2.7.9 TiO2 Nanohelix Gas Sensors with Enhanced Performance and Potential Application as a Building Block of Electronic Noses

Microstructural Characterization and Thermodynamical Study of In-Situ Phase Formation During Spark Plasma Sintering of Tib2-20%Aln-5%Gr

Luminescence properties related anti-phase domain of alpha-Ga2O3

Effects of photowashing treatment on electrical properties of an AlGaN/GaN heterostructure field-effect transistor