• KSBB Journal
• /
• v.4 no.3
• /
• pp.229-234
• /
• 1989

NAD+ analogs, 8-( 6-aminohexyl) aminonicotinamide adenine dinucleotide and N6-[(6- aminohewl)-carbamoylmethyl]- NAD+, were imobilized on bovine caseins by the action of hansglutaminase. It appears that NAD+ analogs bind with $\alpha$S1-and $\beta$-caseins through formation of the r-glutamylamine bond between the amino groups attached to the hexyl chains in NAD+ analogs and the glutaminyl residues in caseins. The NAD+ analogs immobilized on the caseins were enzymatically reducible by alcohol dehydrogenase. $\beta$-Casein was more useful carrier than the $\alpha$S1-casein and 8-substituted NAD+ analog was more effective than N6-substituted one in immobilization. Michaelis constant of 8-substituted NAD+ analog immobilized on $\beta$-casein in alcohol dehydrogenase reaction was similar to that of free from of NAD+ and that of NAD+ analog. Immobilized NAD+ was much more stable at alkaline pH than free NAD+ and its analog while maximum velocity was reduced to 31% of the free NAD+ analog. The coenzyme casein conjugated was recovered almost completely in casein precipitated by calcium.

• Elastomers and Composites
• /
• v.44 no.1
• /
• pp.22-33
• /
• 2009

Recently, elastomer-nanocomposites reinforced with low volume fraction of nanofillers have attracted great interest due to their fascinating properties. The incorporation of nanofillers, such as, layered silicate clays, carbon nanotubes, nanofibers, calcium carbonate, metal oxides or silica nanoparticles into elastomers improves significantly their mechanical, thermal, dynamic mechanical, barrier properties, flame retardancy, etc. The properties of nanocomposites depend greatly on the chemistry of polymer matrices, nature of nanofillers, and the method in which they are prepared. The uniform dispersion of nanofillers in elastomer matrices is a general prerequisite for achieving desired mechanical and physical characteristics. In this paper, current developments in the field of elastomer nanocomposites reinforced with layered silicates, silica, carbon nanotubes, nanofibers and various other nanoparticles have been addressed.

• Journal of the Korean Ceramic Society
• /
• v.47 no.5
• /
• pp.381-386
• /
• 2010

Some basic properties of inorganic coatings hardened by the room temperature reaction with alkalies were examined. The coating paste was prepared from the powders in the system $Al_2O_3-SiO_2$-CaO using blast furnace slag, fly ash and amorphous ceramic fiber after mixing with a solution of sodium hydroxide and water glass. The mineralogical and morphological examinations were performed for the coatings prepared at room temperature and after heating to $1200^{\circ}C$ respectively. The binding force of the coating hardened at room temperature was caused by the formation of fairly dense matrix mainly composed of oyelite-containing amorphous phase formed by the reaction between blast furnace slag and alkali solution. At the temperature, fly ash and ceramic fiber was not reacted but imbedded in the binding phase, giving the fluidity to the paste and reinforcing the coating respectively. During heating up to $1200^{\circ}C$, instead of a break in the coating, anorthite and gehlenite was crystallized out by the reaction among the binding phase and unreacted components in ternary system. The crystallization of these minerals revealed to be a reason that the coating maintains dense morphology after heating. The maintenance of binding force after heat treatment is seemed to be also caused by the formation of welldispersed fiber-like mineral phase which is originated from the shape of the amorphous ceramic fiber used as a raw materials.

• Journal of Conservation Science
• /
• v.6 no.1 s.7
• /
• pp.3-14
• /
• 1997

Twelve Punchong sherds collected in Hakbongni, Kongju where the well known iron-painted on white slip were manufactured from late 15C to early 16C were analyzed for their composition and microstructure. The composition of the body was analyzed by X-ray fluorescence and that of glaze by electron probe micro-analyzer. Microstructure was observed by optical microscope, polarizing microscope, EPMA, and X-ray diffractometer. The results of composition of body and glaze of Hakbongni were compared with those of Punchong from Yongsuri, Boryong which was close to Hakbongni. The composition of body and glaze of these two areas were compared by principal component analysis using SPSS program. Hakbongni bodies have higher silica and flux materials but lower alumina and their glaze have higher silica, soda, iron oxide but lower alumina, calcia. Hakbongni punchong itself is divided into two groups. Their glaze is lime type. There are many remnant minerals, such as quartz, large feldspar mass with partially melted surrounding area, albite, biotite, and iron-oxide. From such a microstructure we can assume that preparation of raw material was rather crude and firing temperature quite low. Iron-painted material is identified as Mg/Fe/Al spinel by composition analysis and XRD pattern.

• Journal of Hydrogen and New Energy
• /
• v.33 no.1
• /
• pp.8-18
• /
• 2022

With rapid industrialization and population growth, fossil fuel use has increased, which has a significant impact on the environment. Hydrogen does not cause contamination in the energy production process, so it seems to be a solution, but it is essential to find an appropriate storage method due to its low efficiency. In this study, Mg-based alloys capable of ensuring safety and high volume and hydrogen storage density per weight was studied, and Mg₂NiH_x synthesized with Ni capable of improving hydrogenation kinetics. In addition, in order to improve thermal stability, a hydrogen storage composite material synthesized with CaO was synthesized to analyze the change in hydrogenation reaction. In order to analyze the changes in the metallurgical properties of the materials through the process, XRD, SEM, BET, etc. were conducted, and hydrogenation behavior was confirmed by TGA and hydrogenation kinetics analysis. In addition, in order to evaluate the impact of the process on the environment, the environmental impact was evaluated through "Material Life Cycle Assessments" based on CML 2001 and EI99' methodologies, and compared and analyzed with previous studies. As a result, the synthesis of CaO caused additional power consumption, which had a significant impact on global warming, and further research is required to improve this.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.45 no.1
• /
• pp.57-67
• /
• 2019

Particulate matters with a diameter of < $10{\mu}m$ (PM10) exert oxidative stress and inflammatory events in various organs. The purpose of this study was to examine the molecular mechanism of reactive oxygen species (ROS) production induced by PM10 in the human epidermal keratinocytes (HEKs). When cultured HEKs were exposed to PM10, ROS production was induced and it was inhibited by apocynin, an antioxidant. The mRNA expression of NADPH oxidase (NOX) family was analyzed in order to examine their role in PM10-induced ROS production. PM10 increased the mRNA expression of NOX1, NOX2, dual oxidase (DUOX) 1 and DUOX2. HEKs expressed DUOX1 and DUOX2 at higher levels compared to other NOXs. The mRNA expression of dual oxidase maturation factors, DUOXA1 and DUOXA2, was also increased by PM10. We examined whether these calcium-dependent enzymes, DUOX1 and DUOX2, mediate the PM10-induced ROS production. A selective intracellular calcium chelator, BAPTA-AM, attenuated ROS production induced by PM10 or calcium ionophore A23187. The small intereference RNA (siRNA)-mediated down-regulation of DUOX2, but not DUOX1, attenuated the ROS production induced by PM10. PM10 increased the expression of inflammatory cytokines such as interleukin $(IL)-1{\beta}$, IL-6, IL-8 and interferon $(IFN)-{\gamma}$. SiRNA-mediated down-regulation of DUOX2 suppressed the PM10-induced expression of $IFN-{\gamma}$ but not other cytokines. This study suggests that DUOX2 plays a crucial role in ROS production and inflammatory response in PM10-exposed keratinocytes.

• Journal of the Mineralogical Society of Korea
• /
• v.27 no.1
• /
• pp.17-30
• /
• 2014

Waste cement generated from recycling processes of waste concrete is a potential raw material for mineral carbonation. For the $CO_2$ sequestration utilizing waste cement, this study was conducted to obtain basic information on the aqueous carbonation methods and the characteristics of carbonate mineral formation. Cement paste was made with W:C= 6:4 and stored for 28 days in water bath. Leaching tests using two additives (NaCl and $MgCl_2$) and two aqueous carbonation experiments (direct and indirect aqueous carbonation) were conducted. The maximum leaching of $Ca^{2+}$ ion was occurred at 1.0 M NaCl and 0.5 M $MgCl_2$ solution rather than higher tested concentration. The concentration of extracted $Ca^{2+}$ ion in $MgCl_2$ solution was more than 10 times greater than in NaCl solution. Portlandite ($Ca(OH)_2$) was completely changed to carbonate minerals in the fine cement paste (< 0.15 mm) within one hour and the carbonation of CSH (calcium silicate hydrate) was also progressed by direct aqueous carbonation method. The both additives, however, were not highly effective in direct aqueous carbonation method. 100% pure calcite minerals were formed by indirect carbonation method with NaCl and $MgCl_2$ additives. pH control using alkaline solution was important for the carbonation in the leaching solution produced from $MgCl_2$ additive and carbonation rate was slow due to the effect of $Mg^{2+}$ ions in solution. The type and crystallinity of calcium carbonate mineral were affected by aqueous carbonation method and additive type.

• Journal of Korean Society of Environmental Engineers
• /
• v.29 no.7
• /
• pp.778-782
• /
• 2007

This study investigated the dechlorination mechanisms of TCE by Fe(II) associated with cement. Batch slurry experiments were peformed to investigate the behaviors of selected ions; Fe(II), Fe(III), $Ca^{2+}$, $SO_4^{2-}$ in cement/Fe(II) system. The kinetic experiments of TCE in cement/Fe(II) systems showed that injected Fe(II) was mostly sorbed on cement within 0.5 day and 90% of injected 200 mM sulfate was sorbed on cement within 0.5 day when $[TCE]_0$ = 0.25 mM and $[Fe(II)]_0$ = 200 mM. The kinetic experiments of TCE in hematite/CaO/Fe((II) systems were conducted for simulation of cement/Fe(II) system. Calcium oxide that is one of the major components in cement hydration reactions or has a reactivity in limited conditions. Hematite assumed the ferric iron oxide component of cement. The reactivities observed in hematite/CaO/Fe(II) system were comparable to those reported for cement/Fe(II) systems containing similar molar amounts of Fe(II). The behavior of Fe(II) and $SO_4^{2-}$ sorbed on solid phase at an early stage of reaction in hematite/CaO/Fe(II) system was similar to that of cement/Fe(II) system. Ferric ion was released from hematite at an early period of reaction at low pH. The experimental evidence of kinetic test using hematite/CaO/Fe(II) system implies that the reactive reductant is a mixed-valent Fe(II)-Fe(III) mineral, which may be similar to green rust. Fe(II) sorbed on cement can be converted to new mineral phase having a reactivity such as Fe(II)-Fe(III) (hydr)oxides in cement/Fe(II) systems.

• Resources Recycling
• /
• v.15 no.4 s.72
• /
• pp.3-12
• /
• 2006

The feasibility for the employment of manganese nodule as an adsorbent for $SO_{2}$ gas has been investigated. The specific surface area of manganese nodule particle, which used in the experiments, was ca. $221.5m^{2}/g$ and the content of sulfur in manganese nodule was observed to significantly increase after $SO_{2}$ was adsorbed on it. The EPMA for the distilled water-washed and methanol-washed manganese nodule particle after $SO_{2}$ adsorption showed that its sulfur content was slightly decreased to 14.7% and 13.1% respectively, from 15.4% before washing. The XRD analysis of manganese nodule showed that todorokite and birnessite, which are manganese oxides, and quartz and anorthite were the major mineralogical components and weak $MnSO_{4}$ peaks were detected after $SO_{2}$ was adsorbed on manganese nodule. For an comparative investigation, limestone was also tested as an adsorbent for $SO_{2}$, however, no peaks for $CaSO_{4}$ were found by XRD analysis after the adsorption of $SO_{2}$. As the size of adsorbent increased, time for breakthrough was decreased and the adsorbed amount of $SO_{2}$ was also diminished. The $SO_{2}$ adsorption was hindered when its flow rate became high and the adsorption capacity of manganese nodule was observed to be superior to that of limestone. In addition, the mixture of manganese nodule and limestone did not show an increase in the adsorption of $SO_{2}$. Finally, as the temperature was raised, the adsorbed amount of adsorbate on manganese nodule was found to be decreased.

• Journal of fish pathology
• /
• v.26 no.2
• /
• pp.89-97
• /
• 2013

The study was carried out to investigate the changes of hematological parameters induced by waterborne exposure of chromium (Cr) in the mullet, Mugil cephalus. The mullet was exposed to sub-chronic concentrations of chromium (0, 25, 50, 100, $200{\mu}g/L$ Cr) for 4 weeks. The major hematological findings were significant decreases in the red blood cell (RBC) count and hematocrit value in mullet exposed to ${\geq}50{\mu}g/L$ Cr. Although serum calcium concentration was significantly reduced at ${\geq}50{\mu}g/L$ Cr, magnesium concentration was found to be significantly increased at ${\geq}100{\mu}g/L$ Cr. The serum glucose and total protein concentrations were significantly increased at $200{\mu}g/L$ Cr. However, serum triglyceride concentration did not show any noticeable changes in the range of $25{\sim}200{\mu}g/L$ Cr of chromium compared to control group during the experimental period. A significant increment of GOT (glutamic oxalate transminase) and GPT (glutamic pyruvate transminase) activities was noticed at ${\geq}100{\mu}g/L$ Cr. These results indicate that hematological and serum biochemical changes in the mullet by waterborne exposure to chromium are affected at more than $50{\mu}g/L$ Cr.