• Bulletin of the Korean Chemical Society
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• v.14 no.1
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• pp.113-117
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• 1993

Good yield synthetic routes for the production of new B-alkyl-dithiaborane clusters are reported. The syntheses of the B-alkyl-dithiaboranes are based on the use of Fischer-type carbene reagents to activate the B-H bonds of dithiaborane for alkyl-addition reactions and are the first examples of transition-mediated reactions of dithiaborane to be reported. Thus, reactions employing arachno-$S_2B_7H_8$- and $(CO)_5M{C(R_1)R_2}$ (M = Cr, W; $R_1 = CH_3,\;C_6H_5;\; R_2 = OCH_3,\;SC_6H_5)$ were found to yield the intermidiate anions I, $[(CO)_5M{C(R_1)R_2S_2B_7H_8}]^-$, which upon protonation gave the corresponding neutral, air-sensitive cluster arachno-4-$RCH_2-6,8-S_2B_7H_8(R=CH_3,\;IIa;\;C_6H_5,\;IIb)$ range from 30 to 35% yield. Complexes IIa and IIb are isoelectronic with arachno-6,8-$S_2B_7H_9$ and, on the basis of the spectroscopic data, are proposed to adopt a similar arachno cage geometry in which an $RCH_2$ units are substituted to 4 position boron atom of the arachno-6,8-$S_2B_7H_9$.

• The Journal of Korean Medicine
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• v.22 no.3
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• pp.21-30
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• 2001

목적 : 이전 연구에서 단삼 추출액이 강력한 항산화 작용이 있음을 확인한 바 있어 단삼 추출액이 신장세뇨관 세포에서 oxidant에 의한 세포사망 및 DNA 손상을 방지하는 지를 조사하고 이러한 효과가 지질의 과산화를 억제하는 효과에 기인하는 지를 시험하였다. 방법 : 신장 근위세뇨관 세포 유래 세포주인 opossum kidney (OK)세포를 이용하여 세포 사망은 frypan blue exclusion방법을 이용하여 평가하였고, DNA손상 정도는 double stranded DNA의 파괴를 측정하여 평가하였다. Oxidant 약물 모델로는 $H_2O_2$를 사용하였다. 결과 : $H_2O_2$는 적용시 간과 농도에 비례하여 세포 사망을 유도하였다. 단삼 추출액은 0.05% 농도에서 $H_2O_2$에 의한 세포사망 및 DNA 손상을 방지하였다. 이러한 방지효과는 $H_2O_2$ 제거 효소인 catalase와 철 착염제인 deferoxamine에 의해서도 나타났다. 그러나 강력한 항산화제인 DPPD는 $H_2O_2$에 의한 세포 사망이나 DNA손상을 방지하지 못하였다. $H_2O_2$는 세포내 ATP 농도를 감소시켰으며. 이러한 감소는 poly (ADP-ribose) polymerase억제제인 3-aminobenzamide에 의해 방지되었으나 단삼 추출액에 의해서는 영향을 받지 않았다. 3-aminobenzamide는 $H_2O_2$에 의한 세포 사망을 방지하였다. $H_2O_2$는 지질의 과산화를 증가시켰으며, 이러한 변화는 단삼 추출액과 DPPD에 의해 방지되었다 결론 : OK 세포에서 $H_2O_2$에 의한 세포사망과 DNA 손상에는 지질의 과산화가 중요한 역할을 하지 않으며, 단삼 추출액의 $H_2O_2$에 의한 세포 사망과 DNA 손상 방지 효과는 항산화 작용이 아닌 다른 기전에 기인하는 것으로 사료된다.

• The Journal of Korean Medicine
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• v.22 no.4
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• pp.58-68
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• 2001

Objectives : This study was designed to investigate the protective mechanisms of Samul-tang (SMT) on $H_2O_2$-induced toxicity in H9c2 cardiomyoblast cells. Methods : The cultured cells were pretreated with SMT and exposed to $H_2O_2$. The cell damage was assessed by using MTT assay. Also, we used Hoechst staining, Western blotting analysis. Results : SMT significantly reduced both $H_2O_2$-induced cell death and chromatin fragmentation. The decrease of Bcl2 expression by $H_2O_2$ was inhibited by SMT. In addition, the increase of Bax expression was also inhibited by SMT. In particular, Fas expression, which is generally recognized as cell death inducing signal by Fas/FasL interaction, was markedly decreased by $H_2O_2$ in a time-dependent manner, whereas this decrease was completely prevented by SMT. The cotreatment of SMT and $H_2O_2$ in H9c2 cells also induced the phosphorylation of ERK in a time-dependent manner. Moreover, PD098059, a specific inhibitor of ERKl/2, attenuated the protective effect of SMT on $H_2O_2$-induced toxicity in H9c2 cardiomyoblast cells. Furthermore, the protective effect of SMT was significantly blocked by treatment of SB203580, a specific inhibitor of p38. Conclusions : Taken together, this study suggests that the protective effects of the water extract of SMT against oxidative damages may be mediated by the modulation of Bel2 and Bax expression via the regulation of ERK and p38 signaling pathway.

• Korean Journal of Materials Research
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• v.25 no.1
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• pp.43-47
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• 2015

$Zn(BH_4)_2$ was prepared by milling $ZnCl_2$ and $NaBH_4$ in a planetary ball mill in an Ar atmosphere, and XRD analysis, SEM observation, FT-IR analysis, DTA, and TGA were performed for synthesized $Zn(BH_4)_2$ samples. 90 wt% $MgH_2$+1.67 wt% $Zn(BH_4)_2(+NaCl)$+5 wt% Ni+1.67 wt% Ti+1.67 wt% Fe (named $90MgH_2+1.67Zn(BH_4)_2(+NaCl)$+5Ni+1.67Ti+1.67Fe) samples were also prepared by milling in a planetary ball mill in an $H_2$ atmosphere. The gas absorption and release properties of the $Zn(BH_4)_2(+NaCl)$ and $90MgH_2+1.67Zn(BH_4)_2(+NaCl)_2(+NaCl)$+5Ni+1.67Ti+1.67Fe samples were investigated. An FT-IR analysis showed that $Zn(BH_4)_2$ formed in the $Zn(BH_4)_2(+NaCl)$ samples prepared by milling $ZnCl_2$ and $NaBH_4$. At the first cycle at $320^{\circ}C$, $90MgH_2+1.67Zn(BH_4)_2(+NaCl)$+5Ni+1.67Ti+1.67Fe absorbed 2.95 wt% H for 2.5 min and 4.93 wt% H for 60 min under 12 bar $H_2$, and released 1.46 wt% H for 10 min and 4.57 wt% H for 60 min under 1.0 bar $H_2$.

• Bulletin of the Korean Chemical Society
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• v.28 no.4
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• pp.635-646
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• 2007

The reaction of gas-phase hydrogen atoms H with H atoms chemisorbed on a graphite surface has been studied by the classical dynamics. The graphite surface is composed of the surface and 10 inner layers at various gas and surface temperatures (Tg, Ts). Three chains in the surface layer and 13 chains through the inner layers are considered to surround the adatom site. Four reaction pathways are found: H2 formation, H-H exchange, H desorption, and H adsorption. At (1500 K, 300 K), the probabilities of H2 formation and H desorption are 0.28 and 0.24, respectively, whereas those of the other two pathways are in the order of 10-2. Half the reaction energy deposits in the vibrational motion of H2, thus leading to a highly excited state. The majority of the H2 formation results from the chemisorption-type H(g)-surface interaction. Vibrational excitation is found to be strong for H2 formed on a cold surface (~10 K), exhibiting a pronounced vibrational population inversion. Over the temperature range (10-100 K, 10 K), the probabilities of H2 formation and H-H exchange vary from 0 to ~0.1, but the other two probabilities are in the order of 10-3.

• The Korean Journal of Physiology and Pharmacology
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• v.8 no.6
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• pp.339-344
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• 2004

Recent data have shown the importance of oxidative stresses in the pathogenesis of inflammatory bowel disease, crohn's disease and ulcerative colitis. $H_2O_2$, reactive oxygen species (ROS) donor, has been reported to act as a signaling molecule involved in a variety of cellular functions such as apo/ptosis and proliferation. In the present study, we investigated viability of cultured ileal smooth muscle cells (ISMC) after stimulation with $H_2O_2$. Trypan blue method revealed that the cell viability of ISMC treated with 1 mM $H_2O_2$ was not different from that of controls at up to 2 h time point, while treatment of ISMC with 1 mM $H_2O_2$ for 48 h finally induced significant decrease in the cell viability. Therefore, we evaluated whether $H_2O_2$ was capable of ERKs activation in ISMC for the short-term exposure and examined whether tyrosine kinase was involved in the process of ERK activation by $H_2O_2$ in ISMC. We also investigated the effects of $H_2O_2$ on activation of SAPK/JNK and p38 MAP kinase in ISMC. Thus, ISMC were cultured and exposed to $H_2O_2$, and western blot analysis was performed with phosphospecific MAP kinase antibodies. Robust activation of ERK occurred within 30 min of 1 mM $H_2O_2$ treatment. $H_2O_2-induced$ ERK activation was attenuated by a tyrosine kinase inhibitor, genistein, indicating that tyrosine kinase was probably involved in the ERK activation by $H_2O_2$. $H_2O_2$ was a moderate activator of SAPK/JNK, while p38 MAP kinase was not activated by $H_2O_2$. We suggest that ERK activation induced by short-term $H_2O_2$ treatment plays a critical role in cellular protection in the early stage of response to oxidative stress. The present study suggests the necessity of identification of MAPK signaling pathways affected by ROS, since it could ultimately elucidate cellular consequences involved in initiation and perpetuation of intestinal tissue damage in the diseases such as crohn's disease and ulcerative colitis, resulted from excessive ROS.

• Membrane Journal
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• v.33 no.4
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• pp.222-232
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• 2023

In this study, a hollow fiber support membrane was prepared by a non-solvent induced phase separation (NIPS) method using a polysulfone (PSf). The prepared hollow fiber support membrane was coated with PDMS and Pebax to prepare a hollow fiber composite membrane. The prepared composite membrane was measured for permeance and selectivity for pure CO₂, H₂, O₂ and N₂. Gas separation performance of the module having the highest selectivity (CO₂/H₂) among the prepared composite membrane modules was measured according to the change in stage cut using simulated gas. The composition of the simulated gas used at this time was 70% CO₂ and 30% H₂. In the 1 stage experiment, it was possible to obtain values of about 60% of H₂ concentration and 12% of H₂ recovery. In order to overcome the low H₂ concentration and recovery, 2 stage serial test was performed, and through this, it was possible to achieve 70% H₂ concentration and 70% recovery. Through this, it was possible to derive a separation process configuration for CO₂/H₂ separation.

• Bulletin of the Korean Chemical Society
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• v.24 no.6
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• pp.832-836
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• 2003

To extend the knowledge of triple bonding between group 6 transition metal and heavier group 14 elements, the structural and bonding aspects of ($η^5-C_5H_5$)$(CO)_2$M≡ER (M = Cr, Mo, W; E = Si, Ge, Sn, Pb) are investigated by hybrid density functional calculations at the B3PW91 level. Substituent effects are also investigated with R = H, Me, $SiH_3$, Ph, $C_6H_3-2,6-Ph_2$, $C_6H_3-2,6-(C_6H_2-2,4,6-Me_3)_2$, and $C_6H_3-2,6-(C_6H_2-2,4,6- iPr_3)_2$.

• Journal of the Korean Chemical Society
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• v.44 no.2
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• pp.127-137
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• 2000

Eleven new compounds that are composed of bis(p-substituted phenyl) terephthalate unitand the decyloxy pendant as lateral were synthesized and their thermal and liquid crystalline properties were studied by the differential scanning calorimetry (DSC) and on a hot-stage of a polarizing microscope. The ter-minal substituent groups of the compound were varied; X= -H(II-H), -F(lI-F), -CII(II-CI), -Br(ll-Br), -I(II-I), -$NO_2(lI-NO_2$), $-CF_3(II-CF_3$), -$OC_2H_5(II-OC_2H_5$), -$OC_4H_9(II-OC_4H_9$), -$C_6H_5(Il-C_6H_5$). The compounds of $II-OC_2H_5,\;II-OC_4H_9$ and $II-C_6H_5$ were monotropically nematic. In contrast, the compounds of Il-H, II-F, II-Cl, II-Br, II-I, $lI-NO_2$, $II-CF_3$, and II-CN did not show liquid crystalline properties.

• KSBB Journal
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• v.10 no.5
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• pp.568-574
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• 1995

To investigate the effect of pH on organic acid production by Anaerobiospirillum succiniciproducens, an anaerobic fermentation was carried out by maintaining the pH of the fermentation broth at 5.8, 6.0, 6.4, 6.8, and 7.2. At various pHs, the concentrations of cell were $1.0∼1.9g/\ell$ which were two to three times higher than those of the other worker's results, and the maximum was obtained at pH 5.8. Substrate consumption was increased by increasing the pH in the range of pH 6.0 to 6.8, while the sugar consumption rate at both pH 5.8 and 7.2 was very slow. The total amount of 2M $Na_2C0_3$ added for adjustment of pH change due to organic acid production was maximum at pH 6.8. Changes of conductivity of the fermentation broth was very simillar to those of 2M $Na_2C0_3$ added at various pHs. Therefore, it is suggested that determination of the amount of organic acid in a broth can be possible by measuring the conductivity. The maximum production yield of lactate based on glucose was 64% for pH 7.2 and 32% for pH 6.8, respectively.