• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.12
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• pp.1568-1575
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• 2008

This study was performed to determine alleviating effects of green tea (GT) on the N-nitrosodimethylamine (NDMA) toxicity to mucins in the rat lingual salivary glands. Sprague-Dawley rats were divided into five groups: untreated (Control), one week-NDMA administrated (NDMA), one week-GT administrated after NDMA for one week (NDMAGT), one week-NDMA administrated with GT (GTNDMA), and one-week NDMA administrated with GT after GT for one week (GTGTNDMA). The mucin properties were elucidated by periodic acid Schiff (PAS) reaction, alcian blue (AB) pH 2.5, AB pH 2.5-PAS, aldehyde fuchsin (AF) pH 1.7-AB pH 2.5, and high iron diamine (HID)-AB pH 2.5 staining. The lingual von Ebner's glands of NDMA group showed some changes such as contraction and destruction of the serous acini, decrease and disappearance of the cytoplasmic granules, vacuolation of cytoplasm, and the mucigenous duct cells. Also, in the lingual mucous glands, enlarged lumens, fused acini, disappearance of granules, vacuolation of cytoplasm, and mucigenous duct cells were observed. All the GT administrated groups had a tendency to recover. GTGTNDMA group recovered almost up to the state of the control group. The lingual von Ebner's glands of NDMA group showed a decrease of neutral mucin and the lingual mucous glands showed a decrease of both neutral and acidic mucins decreased in comparison with control group, although mucous acini secreting strong sulfomucin decreased while those secreting non-sulfomucin (sialomucin) increased. All the GT administrated groups had a tendency to recover. The degree of recovery in the GTNDMA group was stronger than in NDMAGT group and that of the GTGTNDMA group was almost up to the state of the control group. Plus, lingual von Ebner's glands of GTGTNDMA group contained much more neutral mucin than in the control group. In conclusion, it is suggested that NDMA exhibit the toxicity which affects on the mucin properties and which green tea alleviates.

• Applied Chemistry for Engineering
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• v.9 no.2
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• pp.207-213
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• 1998

On the basis of the previous study[1], miscibility were investigated and intermolecular interaction strength for the miscibility were relatively compared for the blends poly{2,2-(m-phenylene)-5,5'-bibenzimidazole}(PBI) with two aromatic polyimides (PIs) synthesized by another dianhydride. Aromatic PAAs were prepared by the reaction of condensation of two diamines, 4,4'-methylene dianiline(4,4'-MDA) and 4,4'-oxydianiline(4,4'-ODA) with 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride(DSDA) using DMAc, and then converted into PIs after curing. PBI/PAA blends were prepared by solution blending. Cast films or precipitated powders of the PBI/PAA blends were cared at a high temperature to transform into PBI/PIs blends. Miscibility and specific intermolecular interaction for miscibility in the blends were investigated, and compared with previous polyimide structures of PBI/PIs blends [1]. Two blends, PBI/DSDA+4,4'-MDA(Blend-V) and PBI/DSDA+4,4'-ODA(Blend-VI), were found miscible : the evidences were optically clear films, synergistic single composition dependent $T_g{\prime}s$, and frequency shifts of N-H stretching band as much as $39{\sim}40cm^{-1}$, and of C=O stretching band near 1730 and $1780cm^{-1}$, 5~6 and $3{\sim}4cm^{-1}$, respectively. The specific intermolecular interactions existing between PBI and PIs were relatively analyzed with the area(A) formed between the $T_g{\prime}s$ of the measured and that of the calculated by the Fox equation at all compositions, the ${\kappa}$ values in Gordon-Taylor equation obtained from the measured $T_g{\prime}s$, and differences of the frequency shifts in the functional N-H and carbonyl stretching band. From the results, the area(A) and the ${\kappa}$ values for Blend-V and VI were smaller than those for Blend-III and IV used in previous study[1]. Differences of the frequency shifts in the functional groups(N-H and C=O) also showed similar tendency. Thus, specific intermolecular interaction strength in terms of hydrogen bonding of PBI/PI blends is dependent upon chemical structures of PIs, that is, PIs it seems that $SO_2$ group in dianhydride(DSDA) has weaker hydrogen bond strength than those of C=O in BTDA. In other words, it implies that the former occupied bulk space than the latter due to the sterric effect.

• Journal of Powder Materials
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• v.12 no.6 s.53
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• pp.447-452
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• 2005

The synthesis and consolidation of titanium silicide by electro-discharge-sintering has been investigated. As-received Ti powder was in flaky shape and the mean particle size was $45.0{\mu}m$, whereas the mean particle size of the pre-milled Si powder with angular shape was $8.0{\mu}m$. Single pulse of 2.5 to 5.0 kJ/0.34g-elemental Ti and pre-milled Si powder mixture with the composition of $Ti-37.5at.\%$ Si was applied using $300{\mu}F$ capacitor. The solid with $Ti_5Si_3$ phase has been successfully fabricated by the discharge with the input energy more than 2.5kJ in less than $129{\mu}sec.$ Hv values were found to be higher than $1000kgf/mm^2$. The formation of $Ti_5Si_3$ occurred through a fast solid state diffusion reaction.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.298-300
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• 2001

Haematococcus pluvialis was cultured autotrophically and mixotrophically for astaxanthin production in bubble column photobioreactors with $CO_2$ and/or acetate supplements. Four different schemes were tested using 5% $CO_2$ balanced with 95% $N_2$ at the aeration rate of 0.1 vvm and supplementation of acetate (l g/L) to the basal medium, MBBM. Average specific growth rates based on cell total volume of each case were 0.138 $day^{-1}$ in control (without $CO_2$ and acetate supplements), 0.125 $day^{-1}$ with only acetate supplementation, 0.315 $day^{-1}$ with only $CO_2$ supplement, 0.304 $day^{-1}$with both $CO_2$ and acetate. The growth rate under $CO_2$ supply was much higher than that without $CO_2$ supply. DCO and DO seemed to be a possible limitation factor. Another interesting observation was the growth rate under $CO_2$ supplement (without acetate) was higher than that under both $CO_2$ and acetate supply. This result is the opposite of the previously reported works. From the result, the existence of acetate may suppress the dark reaction of $CO_2$ fixation or photosynthesis. Conclusively, the growth of H. pluvialis under photoautotrophic condition found to be higher than that under mixotrophic condition.

• Bulletin of the Korean Chemical Society
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• v.8 no.3
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• pp.179-183
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• 1987

Reactions of $Rh(ClO_4)(CO)(AsPh_3)_2$ with unsaturated nitriles and aldehyde, L, produce a series of new cationic rhodium (I) complexes, $[RhL(CO)(AsPh_3)_2]ClO_4$ (L = $CH_2$ = CHCN, $CH_2$ = C($CH_3$)CN, trans-$CH_3CH$ = CHCN, $CH_2$ = CH$CH_2$CN, trans-$C_6H_5CH$ = CHCN, and trans-$C_6H_5CH$ = CHCHD) where L are coordinated through the nitrogen and oxygen, respectively but not through the ${\pi}$-system of the olefinic group. Dissociation constants for the reaction, $[RhL(CO)(AsPh_3)_2]ClO_4$ $\rightleftharpoons$ $Rh(ClO_4)(CO)(AsPh_3)_2$ + L, have been measured to be $1.20{\times}10^{-4}$ M (L = $CH_2$ = CHCN), $1.05{\times}10^{-4}$ M (L = $CH_2$ = C($CH_3$)CN, $3.26{\times}10^{-5}$ M (L = trans-$CH_3$CH = CHCN) and $6.45{\times}10^{-5}$ M (L = $CH_2$ = CH$CH_2$CN) in chlorobenzene at $25^{\circ}C, and higher than those of triphenylphosphine complexes, $[RhL(CO)(AsPh_3)_2]ClO_4$ where L are the corresponding nitriles that are coordinated through the nitrogen atom. The differences in dissociation constants seem to be predominantly due to the differences in ${\Delta}H$ (not due to the differences in ${\Delta}S$). The weaker Rh-N (unsaturated nitriles) bonding in $AsPh_3$ complexes than in $PPh_3$ complexes (based on ${\Delta}H$ values) suggests that the unsaturated nitriles in 2∼5 are good ${\sigma}$-donor and poor ${\pi}$-acceptor.

• Journal of the Korean Ceramic Society
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• v.40 no.9
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• pp.874-880
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• 2003

The effect of h-BN content on microstructure, mechanical properties, and machinability of AlN-BN based machinable ceramics were investigated. The relative density of sintered compact decreased with increasing h-BN content. The four-point flexural strength also decreased from 238 MPa of monolith up to 182 MPa by the addition of 30 vol％ h-BN. Both low Young's modulus and residual tensile stress, formed by the thermal expansion coefficient difference between AIN and h-BN, might cause the strength drop in AlN-BN composite. The crack deflection, and pull-out phenomena increased by the plate-like h-BN. However, the fracture toughness decreased with h-BN content. The second phases, consisted of YAG and ${\gamma}$-Al$_2$O$_3$, were formed by the reaction between Al$_2$O$_3$ and Y$_2$O$_3$. During end-milling process, feed and thrust forces measured for AlN-(10～30) vol％ BN composites decreased with increasing h-BN particles, showing excellent machinability. Also, irrespective of h-BN content, relatively good surfaces with roughness less than 0.5 m (Ra) could be achieved within short lapping time.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.11
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• pp.3031-3038
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• 2009

Cobalt-loaded activated carbon fibers (ACFs) supported titanium dioxide ($TiO_2$) photocatalyst was developed by sol-gel method. The Co-ACFs/$TiO_2$ photocatalyst were characterized by scanning electron microscope (SEM), X.ray diffraction patterns (XRD), energy dispersive X.ray analysis (EDX) and UV-vis absorption spectroscopy. Decomposition efficiency of methylene blue (MB) solution by Co-ACFs/$TiO_2$ photocatalyst reached almost 100% under 300 min reaction. The MB molecules in the bulk solutions were supposed to be condensed around $TiO_2$ particles by adsorption of ACFs. Therefore, the photocatalyst possesses the combined effect of adsorption by activated carbon fibers and photocatalytic reactivity of $TiO_2$ on MB degradation. Due to the cobalt has electron transition effece, thus improved the photodegradation of MB solution.

• Bulletin of the Korean Chemical Society
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• v.18 no.11
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• pp.1166-1172
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• 1997

[FeⅢ(BLPA)DBC]BPh4, a new functional model for the catechol dioxygenases, has been synthesized, where BLPA is bis((6-methyl-2-pyridyl)methyl)(2-pyridylmethyl)amine and DBC is 3,5-di-tert-butylcatecholate dianion. The BLPA complex has a structural feature that iron center has a six-coordinate geometry with N4O2 donor set. It exhibits EPR signals at g=5.5 and 8.0 which are typical values for the high-spin FeⅢ (S=5/2) complex with axial symmetry. The BLPA complex reacts with O2 within a few hours to afford intradiol cleavage (75%) and extradiol cleavage (15%) products which is very unique result of all [Fe(L)DBC] complexes studied. The iron-catecholate interaction of BLPA complex is significantly stronger, resulting in the enhanced covalency of the metal-catecholate bonds and low energy catecholate to FeⅢ charge transfer bands at 583 and 962 nm in CH3CN. The enhanced covalency is also reflected by the isotropic shifts exhibited by the DBC protons, which indicate increased semiquinone character. The greater semiquinone character in the BLPA complex correlates well with its high reactivity towards O2. Kinetic studies of the reaction of the BLPA complex with 1 atm O2 in CH3OH and CH2Cl2 under pseudo-first order conditions show that the BLPA complex reacts with O2 much slower than the TPA complex, where TPA is tris(2-pyridylmethyl)amine. It is presumably due to the steric effect of the methyl substituent on the pyridine ring. Nevertheless, both the high specificity and the fast kinetics can be rationalized on the basis of its low energy catecholate to FeⅢ charge transfer bands and large isotropic NMR shifts for the BLPA protons. These results provide insight into the nature of the oxygenation mechanism of the catechol dioxygenases.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.2
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• pp.169-181
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• 2007

Statement of problem: Titanium is well known as a proper metal for the dental restorations, because it has an excellent biocompatibility, resistance to corrosion, and mechanical property. However, adhesion between titanium and dental porcelains is related to the diffusion of oxygen to the reaction layers formed on cast-titanium surfaces during porcelain firing and those oxidized layers make the adhesion difficult to be formed. Many studies using mechanical, chemical and physical methods to enhance the titanium-ceramic adhesion have been actively performed. Purpose: This study meant to comparatively analyse the adhesion characteristics depending on different titanium surface coatings after coating the casts and wrought titanium surfaces with Au and TiN. Material and method: In this study, the titanium specimens (CP-Ti, Grade 2, Kobe still Co. Japan) were categorized into cast and wrought titanium. The wrought titanium was cast by using the MgO-based investment(Selevest CB, Selec). The cast and wrought titanium were treated with Au coating($ParaOne^{(R)}$., Gold Ion Sputter, Model PS-1200) and TiN coating(ATEC system, Korea) and the ultra low fusing dental porcelain was fused and fired onto the samples. Biaxial flection test was done on the fired samples and the porcelain was separated. The adhesion characteristics of porcelain and titanium after firing and the specimen surfaces before and after the porcelain fracture test were observed with SEM. The atomic percent of Si on all sample surfaces was comparatively analysed by EDS. In addition, the constituents of specimen surface layers after the porcelain fracture and the formed compound were evaluated by X-ray diffraction diagnosis. Result: The results of this study were obtained as follows : 1. The surface characteristics of cast and wrought titanium after surface treatment(Au, TiN, $Al_2O_3$ sandblasting) were similar and each cast and wrought titanium showed similar bonding characteristics. 2. Before and after the biaxial flection test, the highest atomic weight change of Si component was found in $Al_2O_3$ sandblasted wrought titanium(28.6at.% $\rightarrow$ 8.3at.%). On the other hand, the least change was seen in Au-Pd-In alloy(24.5at.% $\rightarrow$ 9.1at.%). 3. Much amount of Si components was uniformly distributed in Au and TiN coated titanium, but less amount of Si's was unevenly dispersed on Al2O3 sandblasting surfaces. 4. In X-ray diffraction diagnosis after porcelain debonding, we could see $Au_2Ti$ compound and TiN coating layers on Au and TiN coated surfaces and $TiO_2$, typical oxide of titanium, on all titanium surfaces. 5. Debonding of porcelain on cast and wrought titanium surface after the biaxial flection is considered as a result of adhesion deterioration between coating layers and titanium surfaces. We found that there are both adhesive failure and cohesive failure at the same time. Conclusion: These results showed that the titanium-ceramic adhesion could be improved by coating cast and wrought titanium surfaces with Au and TiN when making porcelain fused to metal crowns. In order to use porcelain fused to titanium clinically, it is considered that coating technique to enhance the bonding strength between coating kKlayers and titanium surfaces should be developed first.

• Journal of the Korean Society of Food Culture
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• v.38 no.3
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• pp.176-183
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• 2023

In this study, we investigated the effect of the extracts of Cyrtomium fortunei J.Sm. (CFJ) on lipopolysaccharide (LPS) induced inflammation in mouse BV-2 microglial cells. Nitric oxide (NO) production and cell viability were measured using the Griess reagent and the (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) (MTT) assay. Inflammatory cytokines were detected by quantitative polymerase chain reaction (qPCR) in BV-2 microglial cells with and without CFJ extracts. Subsequently, mitogen-activated protein kinases (MAPKs) and antioxidant markers were assessed by western blot analysis. It was found that the CFJ extract significantly decreased the production of pro-inflammatory cytokines (interleukin [IL]-6, tumor necrosis factor [TNF]-α, and IL-1β) and NO in BV-2 microglial cells that were stimulated with LPS. In addition, the expression levels of the phosphorylation of the MAPK family (p38, c-Jun N-terminal kinases [JNK], and extracellular-signal regulated kinase [ERK]) were reduced by CFJ. Also, treatment with CFJ significantly increased the activities of superoxide dismutase type 1(SOD1) and Catalase in BV-2 microglial cells. Our results indicate that CFJ has a potent suppressive effect on the pro-inflammatory responses of activated BV-2 microglia. Therefore, CFJ has the potential to be an effective treatment for neurodegenerative diseases, as it can inhibit the production of inflammatory mediators in activated BV-2 microglial cells.