• BMB Reports
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• v.53 no.7
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• pp.349-356
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• 2020

Mass spectrometry (MS) is an ideal tool for analyzing multiple types of (bio)molecular information simultaneously in complex biological systems. In addition, MS provides structural information on targets, and can easily discriminate between true analytes and background. Therefore, imaging mass spectrometry (IMS) enables not only visualization of tissues to give positional information on targets but also allows for molecular analysis of targets by affording the molecular weights. Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) MS is particularly effective and is generally used for IMS. However, the requirement for an organic matrix raises several limitations that get in the way of accurate and reliable images and hampers imaging of small molecules such as drugs and their metabolites. To overcome these problems, various organic matrix-free LDI IMS systems have been developed, mostly utilizing nanostructured surfaces and inorganic nanoparticles as an alternative to the organic matrix. This minireview highlights and focuses on the progress in organic matrix-free LDI IMS and briefly discusses the use of other IMS techniques such as desorption electrospray ionization, laser ablation electrospray ionization, and secondary ion mass spectrometry.

• International Journal of Precision Engineering and Manufacturing
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• v.5 no.4
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• pp.28-35
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• 2004

Stimulated by novel phenomena observed in molecular aggregates, recent developments in engineering fields of microscopic scales are creating tremendous opportunities for future nanotechnology-based applications. Investigation in the field involves sub-nanosecond or sub-micrometer interactions between extremely small systems, but researches, to date in these physical extremes have been quite limited. Here, we shed light on some of nanoscale phenomena using molecular dynamics simulation: visualization of various phenomena of nanoscales and exploration of size-dependent mechanical properties.

• Toxicological Research
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• v.29 no.1
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• pp.1-6
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• 2013

The process of drug discovery and development requires substantial resources and time. The drug industry has tried to reduce costs by conducting appropriate animal studies together with molecular biological and genetic analyses. Basic science research has been limited to in vitro studies of cellular processes and ex vivo tissue examination using suitable animal models of disease. However, in the past two decades new technologies have been developed that permit the imaging of live animals using radiotracer emission, X-rays, magnetic resonance signals, fluorescence, and bioluminescence. The main objective of this review is to provide an overview of small animal molecular imaging, with a focus on nuclear imaging (single photon emission computed tomography and positron emission tomography). These technologies permit visualization of toxicodynamics as well as toxicity to specific organs by directly monitoring drug accumulation and assessing physiological and/or molecular alterations. Nuclear imaging technology has great potential for improving the efficiency of the drug development process.

• Journal of the Korean Society of Visualization
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• v.10 no.1
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• pp.40-46
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• 2012

Recently micro shock tube is extensively being used in many diverse fields of engineering applications but the detailed flow physics involved in it is hardly known due to high Knudsen number and strong compressibility effects. Unlike the macro shock tube, the surface area to volume ratio for a micro shock tube is very large. This unique effect brings many complexities into the flow physics that makes the micro shock tube different compared with the macro shock tube. In micro shock tube, the inter- molecular forces of working gas can play an important role in specifying the flow characteristics of the unsteady shock wave flow which is essentially generated in all kinds of shock tubes. In the present study, a CFD method was used to predict and visualize the unsteady shock wave flows using the unsteady compressible Navier-Stokes equations, furnished with the no-slip and slip wall boundary conditions. Maxwell's slip equations were used to mathematically model the shock movement at high Knudsen number. The present CFD results show that the propagation speed of the shock wave is directly proportional to the initial pressure and diameter of micro shock tube.

• Korean Chemical Engineering Research
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• v.49 no.3
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• pp.361-366
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• 2011

By using Monte Carlo simulation method we developed a new molecular simulation software which can be used to predict the thermodynamic properties of organic compounds. Starting from molecular structure and intermolecular potential function, rigorous statistical mechanical principles give a probability distribution for the behavior of a system containing many molecules, which enables us to calculate macroscopic thermodynamic properties of the system. The software developed in this work, cheMC, is based on Windows platform providing with easy access. One can efficiently administrate simulations by using an intuitive interface equipped with visualization tool and chart generation. It is expected that molecular simulations supplement the equation of state approach and will play a more important role in the study of thermodynamic properties.

• Journal of Electrical Engineering and Technology
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• v.1 no.3
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• pp.387-395
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• 2006

A review on advanced flow visualization techniques is presented particularly for applications to micro scale heat and mass transport measurements. Challenges, development and applications of micro scale visualization techniques are discussed for the study of heating/evaporating thin films, a heated micro channel, and a thermopneumatic micro pump. The developed methods are (1) Molecular Tagging Fluorescence Velocimetry (MTFV) using 10-nm caged seeding molecules (2) Micro Particle Velocimetry (MPIV) and (3) Ratiometric Laser Induced Fluorescence (LIF) for micro-resolution thermometry. These three methods are totally non-intrusive techniques and would be useful to investigate the temperature and flow characteristics in MEMS. Each of these techniques is discussed in three-fold: (1) its operating principle and operation, (2) its application and measurement results, and (3) its future challenges.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.3
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• pp.298-304
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• 1986

The friction reduction by dilute polymer solutions was investigated experimentally in journal bearings. Flow pattern visualization and torque measurements were performed for a concentric case (.epsilon.=0). The effects of polymer concentration, bearing clearance, and polymer molecular weight on friction reduction were examined. The frictional torque and the intensity of vortices of the case of polymer solution were reduced compared with those of base oil only.

• Macromolecular Research
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• v.17 no.6
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• pp.365-377
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• 2009

In this feature article, we briefly review the new methods we have utilized recently in the investigation of morphology and phase behavior of block copolymers. We first describe the chromatographic fractionation method to purify block copolymers from their side products of mainly homopolymers or block copolymer precursors inadvertently terminated upon addition of the next monomer in the sequential anionic polymerization. The chromatographic method is extended to the fractionation of the individual block of diblock copolymers which can yield the diblock copolymer fractions of different composition and molecular weight, which also have narrower distributions in both molecular weight and composition. A more detailed phase diagram could be constructed from the set of block copolymer fractions without the need of acquiring many block copolymers each prepared by anionic polymerization. The fractions with narrow distribution in both molecular weight and composition exhibit better long-range ordering and sharper phase transition. Next, epitaxial relationships between two ordered structures in block copolymer thin film is discussed. We employed the direct visualization method, transmission electron microtomography(TEMT) to scrutinize the grain boundary structure.

• Mass Spectrometry Letters
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• v.11 no.3
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• pp.41-51
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• 2020

Microbes influence many aspects of human life from the environment to health, yet evaluating their biological processes at the chemical level can be problematic. Mass spectrometry imaging (MSI) enables direct evaluation of microbial chemical processes at the atomic to molecular levels without destruction of valuable two-dimensional information. MSI is a label-free method that allows multiplex spatiotemporal visualization of atomic- or molecular-level information of microbial and microberelated samples. As a result, microbial MSI has become an important field for both mass spectrometrists and microbiologists. In this review, basic techniques for microbial MSI, such as ionization methods and analyzers, are explored. In addition, we discuss practical applications of microbial MSI and various data-processing techniques.

• Transactions of the Korean hydrogen and new energy society
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• v.12 no.1
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• pp.51-63
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• 2001

In this paper molecular dynamics simulations were employed to investigate the structural and dynamic properties of hydrogen ions impacted on the Ni (100) surface with the $45^{\circ}$ incident angle. The initial kinetic energies of the hydrogen ion range from 100 to 1,600 eV. Together with the trajectory visualization of hydrogen ions, we computed scattering and penetration yields, mean energies and angles, and probability and energy distributions as a function of longitudinal and azimuthal directions. In the case of lower energy scattering ions, the multiple collision effects were found to be important to the third layers or lower. For higher energy penetrating ions, compared with the normal incident angle, it was significant the effective channeling effects through the Ni layers and the angle dependencies were indicated both in the longitudinal and the azimuthal angle directions.