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RETRIEVAL OF LOCAL INTERPLANETARY DUST EMISSIVITY BY ASTRO-F
HONG S. S.,KWON S. M.,PYO J.,UENO M.,ISHIGURO M.,USUI F.,WEINBERG J. L. The Korean Astronomical Society 2004 Journal of The Korean Astronomical Society Vol.37 No.4
This is a proposal to probe local part of the interplanetary dust (IPD) cloud complex and retrieve mean volume emissivity of the local IPDs at mid-infrared wavelengths. This will be done by monitoring, with Infrared Camera (IRC) aboard the ASTRO-F, the annual modulation of the zodiacal emission. In pointing mode of the ASTRO-F mission the spacecraft can make attitude maneuvering over approximately ${\pm}1^{\circ}$ range centered at solar elongation $90^{\circ}$ in the ecliptic plane. The attitude maneuvering combined with high sensitivity of the IRC will provide us with a unique opportunity observationally to take derivatives of the zodiacal emission brightness with respect to the solar elongation. From the resulting differential of the brightness over the ${\pm}1^{\circ}$ range, one can directly determine the mean volume emissivity of the local IPDs with a sufficient accuracy to de-modulate the annual emissivity variations due to the Earth's elliptical motion and the dis-alignment of the maximum IPD density plane with respect to the ecliptic. The non-zero eccentricity ($e_{\oplus}$= 0.0167) of the Earth's orbit combined with the sensitive temperature dependence of the Planck function would bring modulations of amplitude at least $3.34\%$ to the zodiacal emission brightness at mid-infrared wavelengths, with which one may determine the IPD temperature T(r) and mean number density n(r) as functions of heliocentric distance r. This will in turn fix the power-law exponent $\delta$ in the relation $T(r) = T_o(r/r_o)^{-\delta}$ for the dust temperature and v in $n(r) = n_o(r/r_o)^-v$ for the density. We discuss how one may de-couple the notorious degeneracy of cross-section, density, reference temperature $T_o$ and exponent $\delta$.
Mechanical properties of multilayered chitosan/CNT nanocomposite films
Sun, F.,Cha, H.R.,Bae, K.,Hong, S.,Kim, J.M.,Kim, S.H.,Lee, J.,Lee, D. Elsevier Sequoia 2011 Materials science & engineering. properties, micro Vol.528 No.21
A multi-performance MWCNT-reinforced chitosan nanocomposite was fabricated by two methods: a freeze-drying process associated with the sublimation and compression (SAC) method; and the casting-evaporation (CE) method. We obtained ordered and multilayered structures with limited porosity, and well-dispersed MWCNT structures of the chitosan nanocomposite, especially with the SAC method. In the case of the nanocomposite films prepared by the CE method, the mechanical strength and elongation were significantly increased by up to about 40% compared with the pure chitosan films. On the other hand, the ordered and porous multilayered pure chitosan films prepared by the SAC method showed significantly lower tensile strength and elongation compared to the pure solid chitosan films. However, the relative enhancement of the mechanical properties of multilayered MWCNT/chitosan nanocomposites with porosity was higher, especially in terms of the elongation, which showed a twofold improvement in strain. The relaxed bond, which could be a relatively strong hydrogen bond, between the functional groups in the chitosan chains and the functionalized surface of the MWCNTs might be stretched under stress, thereby improving the ductility of the multilayered nanocomposite films. In addition, the viscoplastic behavior of the films by the CE method could become more active with increasing strain rate. Interestingly, ordered and porous pure chitosan films did not reveal the viscoplastic behavior; it rather presented strain softening and viscoelastic characteristics. However, the interaction between the chitosan chains and the surface-modified MWCNTs could regenerate viscoplasticity of the chitosan films.
Kumar, P.,Shahzad, F.,Yu, S.,Hong, S.M.,Kim, Y.H.,Koo, C.M. Pergamon Press ; Elsevier Science Ltd 2015 Carbon Vol.94 No.-
In this work, we fabricated reduced large-area graphene oxide (rLGO) with maximum surface area of 1592μm<SUP>2</SUP> through a cost-effective chemical reduction process at low temperature. The product revealed large electrical conductivity of 243+/-12Scm<SUP>-1</SUP> and thermal conductivity of 1390+/-65Wm<SUP>-1</SUP>K<SUP>-1</SUP>, values much superior to those of a conventional reduced small-area graphene oxide (with electrical conductivity of 152+/-7.5Scm<SUP>-1</SUP> and thermal conductivity of 900+/-45Wm<SUP>-1</SUP>K<SUP>-1</SUP>). The rLGO thin film also exhibited not only excellent stiffness and flexibility with Young's modulus of 6.3GPa and tensile strength of 77.7MPa, but also an efficient electromagnetic interference (EMI) shielding effectiveness of ~20dB at 1GHz. The excellent performance of rLGO is attributed to the fact that the larger area LGO sheets include much fewer defects that are mostly caused by the damage of graphene sp<SUP>2</SUP> structure around edge boundaries, resulting in large electrical conductivity. The manufacturing process of rLGO is an economical and facile approach for the large scale production of highly thermally conducting graphene thin films with efficient EMI shielding properties, greatly desirable for future portable electronic devices.
Kim, J.H.,Gripon, P.,Bouezzedine, F.,Jeong, M.S.,Chi, S.W.,Ryu, S.E.,Hong, H.J. North-Holland Pub ; Elsevier Science Ltd 2015 FEBS letters Vol.589 No.2
To improve a previously constructed broadly neutralizing hepatitis B virus (HBV)-specific preS1 humanized antibody (HzKR127), we further humanized it through specificity-determining residue (SDR) grafting. Moreover, we improved affinity by mutating two residues in heavy-chain complementarity-determining regions (CDR), on the basis of the crystal structure of the antigen-antibody complex. HzKR127-3.2 exhibited 2.5-fold higher affinity and enhanced virus-neutralizing activity compared to the original KR127 antibody and showed less immunogenic potential than HzKR127. Enhanced virus-neutralizing activity was achieved by the increased association rate, providing insights into engineering potent antibody therapeutics for HBV immunoprophylaxis. HzKR127-3.2 may be a good candidate for HBV immunoprophylaxis.
Caiazzo, L.,Baccolo, G.,Barbante, C.,Becagli, S.,Bertò,, M.,Ciardini, V.,Crotti, I.,Delmonte, B.,Dreossi, G.,Frezzotti, M.,Gabrieli, J.,Giardi, F.,Han, Y.,Hong, S.-B.,Hur, S.D.,Hwang, H.,Kang, J Elsevier 2017 CHEMOSPHERE - Vol.176 No.-
<P><B>Abstract</B></P> <P>In this work we present the isotopic, chemical and dust stratigraphies of two snow pits sampled in 2013/14 at GV7 (coastal East Antarctica: 70°41′ S - 158°51′ E, 1950 m a.s.l.). A large number of chemical species are measured aiming to study their potentiality as environmental changes markers. Seasonal cluster backward trajectories analysis was performed and compared with chemical marker stratigraphies.</P> <P>Sea spray aerosol is delivered to the sampling site together with snow precipitation especially in autumn-winter by air masses arising from Western Pacific Ocean sector.</P> <P>Dust show maximum concentration in spring when the air masses arising from Ross Sea sector mobilize mineral dust from ice-free areas of the Transantarctic mountains.</P> <P>The clear seasonal pattern of sulfur oxidized compounds allows the dating of the snow-pit and the calculation of the mean accumulation rate, which is 242 ± 71 mm w.e. for the period 2008–2013.</P> <P>Methanesulfonic acid and NO<SUB>3</SUB> <SUP>−</SUP> do not show any concentration decreasing trend as depth increases, also considering a 12 m firn core record. Therefore these two compounds are not affected by post-depositional processes at this site and can be considered reliable markers for past environmental changes reconstruction.</P> <P>The rBC snow-pit record shows the highest values in summer 2012 likely related to large biomass burning even occurred in Australia in this summer.</P> <P>The undisturbed accumulation rate for this site is demonstrated by the agreement between the chemical stratigraphies and the annual accumulation rate of the two snow-pits analysed in Italian and Korean laboratories.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ions, MSA, I, Br, BC and dust record from coastal East Antarctica are presented. </LI> <LI> Seasonal pattern of each markers is highlighted by comparison with δ<SUP>18</SUP>O. </LI> <LI> NssSO<SUB>4</SUB> <SUP>2−</SUP> and δ<SUP>18</SUP>O are chosen for annual layer counting. </LI> <LI> The mean accumulation rate over the period 2008–2013 is 242 ± 71 mm w.e.. </LI> <LI> Nitrate and MSA appear to be well preserved in this high accumulation rate site. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
( Lenny S. F. Ahmadsah ),( Sung Gi Min ),( Seon Kyeong Han ),( Yeun Hong ),( Hae Yeong Kim ) 한국미생물 · 생명공학회 2015 Journal of microbiology and biotechnology Vol.25 No.12
Various salt concentrations (1.0%, 1.3%, 1.6%, 1.9%, and 2.1% labeled as sample A, B, C, D, and E, respectively) were investigated for microbial diversity, identification of Lactic Acid Bacteria (LAB) in salted kimchi cabbage, prepared under laboratory conditions. These samples were stored at 4℃ for 5 weeks in proper aluminum-metalized pouch packaging with calcium hydroxide gas absorber. A culture-independent method known as polymerase chain reaction - denaturing gradient gel electrophoresis was carried out to identify LAB distributions among various salt concentration samples that had identified 2 Weissella (W. confusa and W. soli), 1 Lactobacillus (Lb. sakei), and 3 Leuconostoc (Lc. mesenteroides, Lc. lactis, and Lc. gelidum) in the overall kimchi samples. The pH, titratable acidity, viable cell counts, and coliform counts were not affected by salt variations. In order to assess sensory acceptance, the conducted sensory evaluation using a 9-point hedonic scale had revealed that samples with 1.3% salt concentration (lower than the manufacturer`s regular salt concentration) was more preferred, indicating that the use of 1.3% salt concentration was acceptable in normal kimchi fermentation for its quality and safety. Despite similarities in pH, titratable acidity, viable cell counts, coliform counts, and LAB distributions among the various salt concentrations of kimchi samples, the sample with 1.3% salt concentration was shown to be the most preferred, indicating that this salt concentration was suitable in kimchi production in order to reduce salt intake through kimchi consumptions.