• Animal cells and systems
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• 제8권4호
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• pp.281-288
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• 2004

The change in relationships between methane production and sulfate reduction was investigated in reclaimed rice field soils at different time points after reclamation of tidal flat in Korea. Sulfate concentrations of soils in the ca. 60-year-old and 26-year-old reclaimed rice fields were much lower than that in a natural tidal flat. During 60 d of anaerobic incubation, total methane production and sulfate consumption of the soil slurries were 7.0 ${\mu}$mol $CH_4$/g and 8.2 ${\mu}$mol $SO_4^{2-}$/g in the 60-year-old rice field, 5.6 ${\mu}$mol $CH_4$/g and 12.7 mmol $SO_4^{2-}$/g in the 26-year-old rice field, and ca. 0 mmol $CH_4$/g and 22.4 ${\mu}$mol $SO_4^{2-}$/g in a natural tidal flat. Relative percent electron flow through sulfate reduction in the 60-year-old rice field was much lower (50.8%) compared with the 26-year-old rice field (69.3%) and the tidal flat (99.9%). The addition of an inhibitor of methanogenesis (2-bromoethanesulfonate) had no effect on sulfate reduction in the soil slurries of the reclaimed rice fields. However, instant stimulation of methane production was achieved with addition of an inhibitor of sulfate reduction (molybdate) in the soil slurries from the 26-year-old reclaimed rice field. The specific inhibitor experiments suggest that the relationship of methanogenesis and sulfate reduction might become mutually exclusive or syntrophic depending on sulfate content in the soil after reclamation. Sulfate, thus sulfate reduction activity of sulfate-reducing bacteria, would be an important environmental factor that inhibits methane production and determines the major pathway of electron and carbon flow in anaerobic carbon mineralization of reclaimed rice field soils.

• 한국식품영양과학회지
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• 제33권5호
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• pp.864-868
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• 2004

철분은 생체 내에서 이루어지는 거의 모든 대사에 필수적인 성분이지만, 식음에 포함된 철분의 양은 극히 적어서 철분강화에 대한 연구가 꾸준히 진행되어 왔다. 이에 따라， 철분공여물질을 함유한 리포즘을 이용하여 철분 강화 식품첨가제를 개발하였다. 철분공여물질로 ferrous sulfate와 hemin을 사용하였으며, 이러한 철분 함유 리포좀을 제조하는데 가장 큰 문제점은 ferrous sulfate의 자체 산화와 ferrous sul fate와 hemin으로 인한 리포좀의 지질산화로 지적되었다 또한, ferrous sulfate에 의한 리포좀의 산화 정도는 hemin의 경우보다 낮은 것으로 관찰되었다. Ferrous sulfate의 자동 산화를 억제하기 위하여 수용성 항산화제인 ascorbic acid가 첨가되었으나, 첨가된 ascorbic acid는 ferrous sulfate와 hemin을 함유한 리포좀의 산화를 억제시키지 못했으며, 오히려 ferrous sulfate에 의한 리포좀의 산화를 촉진시키는 것으로 관찰되었다 여기에 지용성 항산화제인 $\alpha$-tocopherol을 추가적으로 첨가함으로써, ferrous sulfate의 자동산화를 억제하고 hemin과 ferrous sulfate에 의한 리포좀의 산화가 억제된 철분 함유 리포좀이 제조되었다.

• 콘크리트학회논문집
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• 제16권3호
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• pp.433-440
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• 2004

In order to improve the performance of concrete, generally, modern cements often incorporate several mineral admixtures. In this study, the experimental included the flow value, air content of mortar containing limestone powder and length change and compressive strength of mortar specimen immersed in sulfate solutions. From the experimental results, the limestone powder cement matrices improved the physical properties and sulfate resistance of cement matrices at $10\%$ replacement ratio of limestone powder. The $30\%$ replacement ratio of limestone powder was significantly deteriorated in sodium sulfate solution. Irrespective of fineness levels of limestone powder, length change and SDF of mortar specimens with only $10\%$ replacement was much superior to the other replacements.

• 신재생에너지
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• 제5권4호
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• pp.80-85
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• 2009

The effects of various organic wastes on anaerobic fermentative hydrogen production were studied using enriched mixed microflora in batch tests. Rotten fruit, corn powder and organic wastewater enriched with sulfate (up to 1,000 mg/L) were used for experiments. Maximum hydrogen production (547.1 mL) was observed from rotten apple with initial substrate concentration of 132.2 g COD/L. The experimental result on sulfate enriched organic wastewater indicated that hydrogen production is not adversely influenced by relatively high sulfate concentration. Residual sulfate content remained at 96-98 % after 75 hours of reaction, which showed that no major sulfate reduction was occurred at pH 5.3-5.5 in the reactor. The volatile fatty acid (VFA) fractions produced during the reaction was in the order of butyrate > acetate > propionate in all experiments. The results of this study would be useful for controlling the conditions on fermentative hydrogen production using different feedstocks.

• 상하수도학회지
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• 제23권6호
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• pp.843-853
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• 2009

The sediment samples were collected from Seonakdong River and were analyzed for sulfide species such Acid Volatile Sulfide(AVS) and Elemental Sulfur(ES) and Chromium Reducible Sulfide(CRS). Then characteristics of the formation of sulfide species were investigated for six selected samples. Finally the relationship between environmental factors and sulfate reducing rate(SRR) was investigated using two selected samples. Concentrations of AVS and CRS were relatively high, which suggests that organics input to the sediments has been continued until recently and that potential of heavy metals leaching from the sediments is low. SRR in the sediments was closely related to fraction of fine particles(silt+clay) and also to dissolved organic carbon content of the sediment(DOCsed). The dependences of environmental factors such as organic content, temperature, sulfate concentration on the SRR was relatively strong in the selected experiments conducted with the samples from Noksan gate and Daejeo gate samples. The environmental factor dependencies were stronger in the Noksan gate samples than in the Daejeo gate samples, which is probably due to higher surface area of the Noksan gate sediments.

• 한국재료학회지
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• 제18권3호
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• pp.163-168
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• 2008

The morphology of three-dimensional (3D) cross-linked electrodeposits of copper and tin was investigated as a function of the content of metal sulfate and acetic acid in a deposition bath. The composition of copper sulfate had little effect on the overall copper network structure, whereas that of tin sulfate produced significant differences in the tin network structure. The effect of the metal sulfate content on the copper and tin network is discussed in terms of whether or not hydrogen evolution occurs on electrodeposits. In addition, the hydrophobic additive, i.e., acetic acid, which suppresses the coalescence of evolved hydrogen bubbles and thereby makes the pore size controllable, proved to be detrimental to the formation of a well-defined network structure. This led to a non-uniform or discontinuous copper network. This implies that acetic acid critically retards the electrodeposition of copper.

• Fisheries and Aquatic Sciences
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• 제12권3호
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• pp.194-202
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• 2009

Sulfated fucans are known to have both anti-thrombotic and anti-coagulant activities. In this study, the variation in platelet aggregation and anti-coagulant activities was investigated in vitro with regard to administered dose, molecular weight distribution, sulfate content, and sugar composition in two algal fucoidans from Eisenia bicyclis and Undaria pinnatifida sporophylls (Mekabu). The anti-coagulant activity largely correlated with sulfate content and with molecular weight distribution in a dose-dependent manner. However, both fucoidans demonstrated inhibitory responses to ADP-induced platelet aggregation in dose- and structure-dependent manners that contrasted with the anti-coagulant activity. Neither molecular weight distribution nor sulfate content greatly affected platelet-aggregation inhibition (PA-inhibition) by the fucoidan fractions, whereas anti-coagulant activity was sensitive to these structural factors. Interestingly, an E. bicyclis fucoidan fraction exhibited almost complete PA-inhibition at a treatment dose of 500 mg/mL while retaining weak anti-coagulant activity. In conclusion, these observations suggest that fucoidan may be a useful anti-thrombotic or anti-platelet agent in various arterial thrombotic disorders, including post-vascular intervention with controlled bleeding complications, due to its anti-coagulant modulating activity.

• 한국토양비료학회지
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• 제19권1호
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• pp.9-13
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• 1986

황산칼리와 인산암모니아를 주축으로 한 경기화학공업주식회사인 시제 딸기복비의 비효를 염화칼리, 황산칼리, 질산암모니아에 대비하여 비닐하우스에서 딸기, 보교조생 (Fragaria Grand EHRD)으로 시험한 결과를 요약하였다. 가수분해당을 포함하는 전당의 함량은 높였다. 일반적으로 염화칼리보다 황산칼리가 딸기즙의 딸기의 생육, 화방수.,수량에 미친 시제 딸기복비의 효과는 염화칼리, 황산칼리, 질산암모니아와 통계적인 차이가 없으나 딸기즙의 환원당, 묽은 산당분함량을 높였으며 딸기복비가 딸기즙의 당 함량을 높인것도 황산칼리 때문인 것으로 생각되었다.

• 한국세라믹학회지
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• 제30권1호
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• pp.7-16
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• 1993

Effect of sulfate on the reactionof C3S formation in presence of clinker melt and its appearance in clinker were investigated, using (NH4)2SO4 and CaSO4 as sulfate sources. When (NH4)2SO4 and CaSO4 were added, both showed the similar results, 1.0wt% of sulfate could promoted the reaction of C3S formation, however for its content of more than 2.0wt%, the formation of C3S was prevented. Residual limit of sulfate to C3S formation is about 1.4wt%. Appearances of sulfate were C4A3l and CaSO4 in interstitial phase. For the addition of (NH4)2SO4 or CaSO4 of 20wt%~4.0wt%, C3S grains showed the hypertrophic growth. We might consider that, because sulfate reduced the surface tension and viscosity of the clinker melt, C3S crystals were precipitated below 140$0^{\circ}C$, and the crystlas of C3S were coalesced and linked in the same crystallographical direction with increasing temperature becuase of their rapid growth rate.

• 한국산학기술학회논문지
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• 제17권6호
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• pp.9-17
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• 2016

Alcalase와 protamex의 두 가지 단백질 분해효소를 사용하여 홍어연골로부터 콘드로이틴 황산을 분해추출하고, 몇가지 물리화학적 공정을 적용하여 고순도의 콘드로이틴 황산을 얻기 위한 정제방법을 검토하였다. 2% alcalase로 홍어연골을 가수분해하고 $40^{\circ}Brix$로 농축한 추출물의 수율은 23.3%이었으나, 에탄올로 1회 및 2회 추가 정제한 경우 각각 8.47%, 3.37%로 얻어졌다. 1% alcalase와 1% protamex로 혼합 사용하여 추출분해하고, $40^{\circ}Brix$로 농축한 다음 1회 에탄올 정제한 경우는 추출수율이 16.62%로 측정되어 단백질 분해효소를 혼합한 경우가 더 높은 수율을 보였다. 추출된 콘드로이틴 황산의 함량은 에탄올 용매비에 따라 39.88~45.08%의 범위로 측정되었으며, alcalase만 사용시에는 용매비 1:1에서 42.92%로 가장 높게 측정되었고, alcalase와 protamex를 혼합 사용한 경우에는 용매비 1:2에서 45.08%로 가장 높았으며, 에탄올에 의한 농축물의 정제시 교반 시간은 2시간이 효과적이었다. 콘드로이틴 황산의 GPC (Gel Permeation Chromatography) 측정 결과 alcalase와 protamex를 혼합 사용한 경우 에탄올 정제 횟수에 따라 콘드로이틴 황산의 분자량과 순도는 각각 11만~31만 Da.과 24.87%~49.92%의 범위로 측정되었으며, 한외여과를 통하여 분자량 약 11만 Da., 최고 순도 53.93%의 콘드로이틴 황산을 얻을 수 있었다. 콘드로이틴 황산의 냄새 강도는 에탄올 정제만으로는 33%, 활성탄 처리와 에탄올 정제를 병행한 경우 38%의 감소효과가 얻어졌으며, 활성탄 처리와 2회의 에탄올 정제시 암모니아는 52.1%, TMA (trimethylamine)는 37.89%의 탈취효과가 있었으나, 냄새성분의 충분한 제거를 위해서는 추가적인 물리화학적 처리가 요구되었다.