• Title/Summary/Keyword: molecular structural property

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Adhesion Properties on the Molecular Weight and Various Substrates of Multi-layered Structural Acrylic Adhesive (다층구조형 아크릴 점착제의 분자량 및 피착재 종류에 따른 접착특성)

  • Kim, Dong-Bok
    • Polymer(Korea)
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    • v.39 no.3
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    • pp.514-521
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    • 2015
  • In this study, we would like to describe peel strength and dynamic shear property on various substrates of multi-layered structural double-sided adhesive tape with or without adhesive (AD) prepared by UV curing for an automobile, construction, and display junction. According to adapt the adhesive, the peel and dynamic shear strength of adhesion tape prepared with acrylic foam or various plastic substrates increased with increasing molecular weight, however, decreased over 650000 molecular weight. The adhesion property shows high value at the thin AD layer with decreasing temperature. The interface property shows highest at MW 615000 (AD-4), and the interface junction below MW 615000 resulted to divide from acrylic foam and adhesive layer. From this study, the multi-layered structural double-sided adhesive tapes seem to be a useful for industrial area such as a low surface energy plastic material and curved substrate.

Surface Morphology of AlSb on GaAs Grown by Molecular Beam Epitaxy and Real-time Growth Monitoring by in situ Ellipsometry

  • Kim, Jun Young;Lim, Ju Young;Kim, Young Dong;Song, Jin Dong
    • Applied Science and Convergence Technology
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    • v.26 no.6
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    • pp.214-217
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    • 2017
  • AlSb is a promising material for optical devices, particularly for high-frequency and nonlinear-optical applications. We report the effect of growth temperature on structural properties of AlSb grown on GaAs substrate. In particular we studied the surface of AlSb with the growth temperature by atomic force microscopy, and concluded that optimized growth temperature of AlSb is $530^{\circ}C$. We also show the result of real-time monitoring of AlSb growth by in situ ellipsometry. The results of the structural study are good agreement with the previous reported ellipsometric data.

Physicochemical Properties of Starch Affected by Molecular Composition and Structures: A Review

  • Srichuwong, Sathaporn;Jane, Jay-Iin
    • Food Science and Biotechnology
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    • v.16 no.5
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    • pp.663-674
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    • 2007
  • Starches from different botanical sources differ in the ratio of amylose to amylopectin contents, molecular structures of amylose and amylopectin, granule morphology, and minor-component contents. These structural features result in different gelatinization, pasting, retrogradation properties, and enzyme digestibility of starch granules. In this review, compositions and molecular structures of starches and their effects on the physicochemical properties are summarized and discussed.

Molecular Mechanisms of Synaptic Specificity: Spotlight on Hippocampal and Cerebellar Synapse Organizers

  • Park, Dongseok;Bae, Sungwon;Yoon, Taek Han;Ko, Jaewon
    • Molecules and Cells
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    • v.41 no.5
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    • pp.373-380
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    • 2018
  • Synapses and neural circuits form with exquisite specificity during brain development to allow the precise and appropriate flow of neural information. Although this property of synapses and neural circuits has been extensively investigated for more than a century, molecular mechanisms underlying this property are only recently being unveiled. Recent studies highlight several classes of cell-surface proteins as organizing hubs in building structural and functional architectures of specific synapses and neural circuits. In the present minireview, we discuss recent findings on various synapse organizers that confer the distinct properties of specific synapse types and neural circuit architectures in mammalian brains, with a particular focus on the hippocampus and cerebellum.

Molecular Dynamics Simulation of Liquid Alkanes III. Thermodynamic, Structural, and Dynamic Properties of Branched-Chain Alkanes

  • 이송희;이홍;박형숙
    • Bulletin of the Korean Chemical Society
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    • v.18 no.5
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    • pp.501-509
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    • 1997
  • In recent papers[Bull. Kor. Chem. Soc. 1996, 17, 735; ibid 1997, 18, 478] we reported results of molecular dynamics (MD) simulations for the thermodynamic, structural, and dynamic properties of liquid normal alkanes, from n-butane to n-heptadecane, using three different models. Two of the three classes of models are collapsed atomic models while the third class is an atomistically detailed model. In the present paper we present results of MD simulations for the corresponding properties of liquid branched-chain alkanes using the same models. The thermodynamic property reflects that the intermolecular interactions become weaker as the shape of the molecule tends to approach that of a sphere and the surface area decreases with branching. Not like observed in the straight-chain alkanes, the structural properties of model Ⅲ from the site-site radial distribution function, the distribution functions of the average end-to-end distance and the root-mean-squared radii of gyration are not much different from those of models Ⅰ and Ⅱ. The branching effect on the self diffusion of liquid alkanes is well predicted from our MD simulation results but not on the viscosity and thermal conductivity.

Investigation of Physical Property Change in Modified Rice Starch by Ultra Fine Pulverization (초미세분쇄를 이용한 쌀 변성전분의 물리적 특성 변화구명)

  • Han, Myung-Ryun;Chang, Moon-Jeong;Kim, Myung-Hwan
    • Applied Biological Chemistry
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    • v.50 no.3
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    • pp.160-166
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    • 2007
  • This study was performed to analyze the molecular structural and physical properties changes of modified rice starch, which particle structure was broken using high impact planetary mill and ultra fine pulverizing techniques. The average diameter and specific surface area of rice starch after pulverization decreased 20% and increased 25%, respectively. Low molecular substances content in rice starch using GPC (gel permeation chromatography) increased from 36.5% to 59.5% after pulverizing of rice starch. Damaged starch contents in rice starch also increased from 16.4% to 99.2% after pulverizing of rice starch. Water holding capacity, solubility and transmittance of rice starch after pulverization increased compared to those of control. Apparent viscosity value of rice starch after pulverization decreased to 7% in control based on $30^{\circ}C$ and 20 RPM conditions.

Investigation of Physical Property Change in Modified Corn Starch by Ultra Fine Pulverization (초미세분쇄를 이용한 옥수수 변성전분의 물리적 특성 변화 구명)

  • Han, Myung Ryun;Kim, Ae Jung;Chang, Moon Jeong;Lee, Soo Jeong;Kim, Hee Sun;Kim, Myung Hwan
    • Food Engineering Progress
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    • v.13 no.4
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    • pp.335-340
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    • 2009
  • This study was performed to analyze changes in the molecular structural and physical properties of modified corn starch, in which particle structure was broken using high impact planetary mill and ultra fine pulverizing techniques. The average diameter and specific surface area of the modditied corn starch after pulverization decreased 50% and increased 567%, respectively. Content of low molecular substances mersured using gel permeation chromatography (GPC) increased from 21.0% to 86.5% after pulverizing corn starch. Damaged starch content also increased from 9.63% to 83.57% after pulverizing corn starch. After pulverization, gel formation capacity corn starch was reduced compared to that of control by structure breakdown.

Structure of a DNA Duplex Containing a Site-Specific Dewar Isomer: Structural Influence of the 3'-T.G base pair of the Dewar product.

  • Lee, Joon-Hwa;Choi, Byong-Seok
    • BMB Reports
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    • v.33 no.3
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    • pp.268-275
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    • 2000
  • In contrast to the pyrimidine (6-4)pyrimidone photoproduct [(6-4) adduct], its Dewar valence isomer (Dewar product) is low mutagenic and produces a broad range of mutations with a 42 % replicating error frequency. In order to determine the origin of the mutagenic property of the Dewar product, we used experimental NMR restraints and molecular dynamics to determine the solution structure of a Dewar·lesion DNA decamer duplex, which contains a mismatched base pair between the 3'-T residue and an opposed G residue. The 3'-T of the Dewar lesion forms stable hydrogen bonds with the opposite G residue. The helical bending and unwinding angles of the DW/GA duplex, however, are much higher than those of the DW/AA duplex. The stable hydrogen bonding of the G 15 residue does not increase the thermal stability of the overall helix. It also does not restore the distorted backbone conformation of the DNA helix that is caused by the forming of a Dewar lesion. These structural features implicate that no thermal stability, or conformational benefits of G over A opposite the 3'-T of the Dewar lesion, facilitate the preferential incorporation of an A. This is in accordance with the A rule during translesion replication and leads to the low frequent $3'-T{\rightarrow}C$ mutation at this site.

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Thermal Conductivity Analysis of Amorphous Silicon Formed by Natural Cooling: A Molecular-dynamics Study

  • Lee, Byoung Min
    • Journal of the Korean Ceramic Society
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    • v.53 no.3
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    • pp.295-300
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    • 2016
  • To investigate the thermal conductivity and the structural properties of naturally cooled excimer-laser annealed Si, molecular-dynamics (MD) simulations have been performed. The thermal conductivity of crystalline Si (c-Si) was measured by direct method at 1000 K. Steady-state heat flow was measured using a stationary temperature profile; significant deviations from Fourier's law were not observed. Reliable processes for measuring the thermal conductivity of c-Si were presented. A natural cooling process to admit heat flow from molten Si (l-Si) to c-Si was performed using an MD cell with a size of $48.9{\times}48.9{\times}97.8{\AA}^3$. During the cooling process, the temperature of the bottom $10{\AA}$ of the MD cell was controlled at 300 K. The results suggest that the natural cooling system described the static structural property of amorphous Si (a-Si) well.

Structural Bioinformatics Analysis of Disease-related Mutations

  • Park, Seong-Jin;Oh, Sang-Ho;Park, Dae-Ui;Bhak, Jong
    • Genomics & Informatics
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    • v.6 no.3
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    • pp.142-146
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    • 2008
  • In order to understand the protein functions that are related to disease, it is important to detect the correlation between amino acid mutations and disease. Many mutation studies about disease-related proteins have been carried out through molecular biology techniques, such as vector design, protein engineering, and protein crystallization. However, experimental protein mutation studies are time-consuming, be it in vivo or in vitro. We therefore performed a bioinformatic analysis of known disease-related mutations and their protein structure changes in order to analyze the correlation between mutation and disease. For this study, we selected 111 diseases that were related to 175 proteins from the PDB database and 710 mutations that were found in the protein structures. The mutations were acquired from the Human Gene Mutation Database (HGMD). We selected point mutations, excluding only insertions or deletions, for detecting structural changes. To detect a structural change by mutation, we analyzed not only the structural properties (distance of pocket and mutation, pocket size, surface size, and stability), but also the physico-chemical properties (weight, instability, isoelectric point (IEP), and GRAVY score) for the 710 mutations. We detected that the distance between the pocket and disease-related mutation lay within $20\;{\AA}$ (98.5%, 700 proteins). We found that there was no significant correlation between structural stability and disease-causing mutations or between hydrophobicity changes and critical mutations. For large-scale mutational analysis of disease-causing mutations, our bioinformatics approach, using 710 structural mutations, called "Structural Mutatomics," can help researchers to detect disease-specific mutations and to understand the biological functions of disease-related proteins.