• Corrosion Science and Technology
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• 제16권2호
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• pp.69-75
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• 2017

Zinc coating on carbon steels give the higher corrosion resistance in chloride containing environments and in carbonated concrete. However, hydrogen evolution accompanies the corrosion of zinc in the initial activity in fresh concrete, which can lead to the formation of a porous structure at the reinforcement -concrete interface, which can potentially reduce the bond-strength of the reinforcement with concrete. The present study examines the mechanism of the corrosion of hot-dip galvanized steel in detail, as in the model pore solutions and real concrete. Calcium ion plays an important role in the corrosion mechanism, as it prevents the formation of passive layers on zinc at an elevated alkalinity. The corrosion rate of galvanized steel decreases in accordance with the exposure time; however, the reason for this is not the zinc transition into passivity, but the consumption of the less corrosion-resistant phases of hot-dip galvanizing in the concrete environment. The results on the electrochemical tests have been confirmed by the bond-strength test for the reinforcement of concrete and by evaluating the porosity of the cement adjacent to the reinforcement.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.115-116
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• 2023

This study aims to investigate and improve the carbon dioxide sequestration capability and the mechanical properties of non-hydraulic low calcium silicate cement especially designed for CO₂ reaction and ordinary Portland cement subjected to the carbonation curing facilitating pH swing method. Nitric acid (HNO₃) was utilized as an liquid for the mixing of cement paste to enhance the initial dissolution of Ca ions from the cements by promoting low pH environment and prevent the direct precipitation of Ca with the anion, owing to the high solubility of Ca(NO₃)₂ in water. The results presented that the higher the concentration of HNO₃, the higher the compressive strength and CO₂ sequestration (until 0.1 M). Ca dissolution caused by the harsh acid attack onto the anhydrous cement particle lead to the higher carbonation reaction degree, forming abundant CaCO₃ crystals after the reaction. However, cement paste mixed with excessively high concentration of HNO₃ presented deterioration due to the too harsh pH environment and abundant NO₃- ions which are known to retard the reaction of cement.

• Journal of Yeungnam Medical Science
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• 제40권4호
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• pp.328-334
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• 2023

An aging population and changes in dietary habits have increased the incidence of diabetes, resulting in complications such as diabetic foot ulcers (DFUs). DFUs can lead to serious disabilities, substantial reductions in patient quality of life, and high financial costs for society. By understanding the etiology and pathophysiology of DFUs, their occurrence can be prevented and managed more effectively. The pathophysiology of DFUs involves metabolic dysfunction, diabetic immunopathy, diabetic neuropathy, and angiopathy. The processes by which hyperglycemia causes peripheral nerve damage are related to adenosine triphosphate deficiency, the polyol pathway, oxidative stress, protein kinase C activity, and proinflammatory processes. In the context of hyperglycemia, the suppression of endothelial nitric oxide production leads to microcirculation atherosclerosis, heightened inflammation, and abnormal intimal growth. Diabetic neuropathy involves sensory, motor, and autonomic neuropathies. The interaction between these neuropathies forms a callus that leads to subcutaneous hemorrhage and skin ulcers. Hyperglycemia causes peripheral vascular changes that result in endothelial cell dysfunction and decreased vasodilator secretion, leading to ischemia. The interplay among these four preceding pathophysiological factors fosters the development and progression of infections in individuals with diabetes. Charcot neuroarthropathy is a chronic and progressive degenerative arthropathy characterized by heightened blood flow, increased calcium dissolution, and repeated minor trauma to insensate joints. Directly and comprehensively addressing the pathogenesis of DFUs could pave the way for the development of innovative treatment approaches with the potential to avoid the most serious complications, including major amputations.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제50권4호
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• pp.177-188
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• 2024

The endoplasmic reticulum (ER) is crucial for protein synthesis, transport, and folding, as well as calcium storage, lipid and steroid synthesis, and carbohydrate metabolism. Endoplasmic reticulum stress (ERS) occurs when misfolded or unfolded proteins accumulate in the ER lumen due to increased protein secretion or impaired folding. While the role of ERS in disease pathogenesis has been widely studied, most research has focused on extraoral diseases, leaving the role of ERS in intraoral diseases unclear. This review examines the role of ERS in oral diseases and oral fibrosis pathogenesis. A systematic search of literature through July 2023 was conducted in the MEDLINE database (via PubMed) using specific terms related to ERS, oral diseases, and fibrosis. The findings were summarized in both table and narrative form. Emerging evidence indicates that ERS significantly contributes to the pathogenesis of oral diseases and fibrosis. ERS-induced dysregulation of protein folding and the unfolded protein response can lead to cellular dysfunction and inflammation in oral tissues. Understanding the relationship between ERS and oral disease pathogenesis could offer new therapeutic targets for managing oral health and fibrosis-related complications.

• 청정기술
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• 제28권4호
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• pp.269-277
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• 2022

생물학적 효소 반응 산업의 발전으로 인해 바이오매스 자원으로부터 젖산을 대량 생산하는 것이 가능해짐에 따라 젖산의 추가적인 탈수 반응을 통해 고흡수성 수지 SAP, 디스플레이의 점접착제 등의 원료가 되는 아크릴산을 생산하는 친환경 공정이 많은 주목을 받고 있다. 본 연구에서는 젖산 탈수 반응에서 높은 활성을 가지나, 비활성화가 빠른 단점을 가지는 NaY 제올라이트 촉매의 산점 및 염기점을 조절하여, 높은 아크릴산 선택도를 장시간 유지 가능한 촉매를 개발하고자 하였다. 첫번째로 NaY 모촉매에 부분적으로 칼슘을 치환하여 산/염기도를 변화시키고자 하였으며, 이온 교환법과 초기습식 함침법을 모두 적용하여 그 효과를 탐색하였다. 그 결과 직접적으로 Ca를 함침하는 것이 선택도 및 안정성 측면에서 우수한 것을 확인하였으며, 16시간 반응 동안 40% 수율의 AA를 안정적으로 생산하였다. 산/염기 특성 분석 결과, 함침된 Ca는 주로 CaO 형태로 촉매 외피에 존재하면서, 젖산 탈수 반응을 위한 추가적인 염기점으로 작용하는 것으로 나타났다. 추가적으로 NaY 모촉매의 산세기를 약화시키면서 기공 내외적으로 Ca을 고르게 분산시키기 위해, KOH 처리를 통한 탈규소화 후, Ca를 함침하였다. 그러나 기존 Ca-NaY 촉매 대비 아크릴산 선택도가 증진되는 효과는 관찰하지 못하였다. 최종적으로 KOH 처리 촉매에서 Ca 담지양을 1 wt%에서 5 wt%로 증가시켜 염기점 양을 증진시켜 보았다. 그 결과, 기존 1 wt% Ca가 함침된 촉매에 비해 아크릴산 선택도를 65%까지 증진시킬 수 있었으며, 24시간 반응 동안 촉매 안정성 또한 꾸준하게 유지되어, 젖산 탈수 반응에서 염기점 조절이 선택도 및 안정성 향상에 중요한 변수임을 제시하였다.

• 한국식품영양과학회지
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• 제33권6호
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• pp.958-964
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• 2004

본 연구에서는 가임기 동안 저칼슘을 섭취한 흰쥐에게 임신기와 수유기에 걸쳐 장기간 칼슘보충수준을 달리했을 때, 어미쥐와 새끼쥐의 골격상태와 무기질 대사가 어떻게 변화하는 가를 알아보고, 가임기 동안의 칼슘부족 상태를 어느 정도 회복시킬 수 있는지를 검토하고자 하였다. 암컷 흰쥐를 이용하여 5주간의 비임신기간 동안 저칼슘을 섭취시킨 후 다시 세 군으로 나누어 고(high 1.5%), 중(normal 0.5%), 저(low 0.15%) 수준의 칼슘을 함유한 실험식이를 임신기와 수유기의 총 6주 동안 각각 급여하였다. 전 실험기간 동안 정상 칼슘 식이를 섭취한 군을 정상대조군으로 하였다. 임신전이나 임신, 수유기 동안 체중 및 식이섭취량은 식이 칼슘 수준에 따른 차이를 보이지 않았다. 비임신기간 동안 저칼슘을 섭취한 모든 실험군에서 정상칼슘을 섭취한 군에 비해 어미쥐의 혈청 총 단백질 농도가 감소되었다. 그리고 비임신기간 동안 저칼슘 섭취에 의해 저하된 어미쥐의 골격상태는 임신, 수유기간 동안 정상수준 이상의 칼슘을 보충했을 때 정상수준에 가깝게 회복되었다. 그러나, 임신, 수유기간 동안 고수준의 칼슘보충은 어미쥐의 혈청에서 인, 마그네슘 및 철의 함량을, 대퇴골과 요추에서는 마그네슘의 함량을 유의적으로 저하시켰다. 반면, 신장에서는 칼슘, 인 및 마그네슘 함량을 높여서 무기질을 축적시켰다. 임신, 수유기 동안 어미쥐의 칼슘섭취 수준이 새끼쥐에 미친 영향을 보면, 어미쥐의 지속적인 저칼슘 식이 섭취가 새끼쥐의 대퇴골 회분량 및 칼슘, 인과 마그네슘 함량을 유의적으로 낮추었고, 고수준의 칼슘을 보충한 경우에는 새끼쥐의 혈청 마그네슘 농도와 아연 농도를 유의적으로 낮추었다. 이상의 결과에서 비임신기에 칼슘 섭취 부족은 모체의 골격 중량, 강도 및 회분함량을 저하시킬 뿐만 아니라 이러한 칼슘 섭취부족상태가 임신, 수유기까지 이어진다면 그 영향이 모체뿐만 아니라 그 자손에게까지 미칠 수 있음이 밝혀졌다. 한편 임신 전에 불충분한 칼슘을 섭취했다고 할 지라도 임신, 수유기간 동안 적절하게 칼슘을 보충하면 모체의 골격상태 및 무기질 함량은 회복될 수 있는 것으로 나타났다. 그러나, 고칼슘의 보충은 혈청 단백질 농도뿐만 아니라 다른 무기질의 농도를 저하시켜 체내 무기질 불균형을 초래할 수 있으므로 임신, 수유기 동안 칼슘보충제의 적절한 섭취가 요구된다.

• The Korean Journal of Physiology and Pharmacology
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• 제22권2호
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• pp.215-223
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• 2018

Intracellular $Ca^{2+}$ mobilization is closely linked with the initiation of salivary secretion in parotid acinar cells. Reactive oxygen species (ROS) are known to be related to a variety of oxidative stress-induced cellular disorders and believed to be involved in salivary impairments. In this study, we investigated the underlying mechanism of hydrogen peroxide ($H_2O_2$) on cytosolic $Ca^{2+}$ accumulation in mouse parotid acinar cells. Intracellular $Ca^{2+}$ levels were slowly elevated when $1mM\;H_2O_2$ was perfused in the presence of normal extracellular $Ca^{2+}$. In a $Ca^{2+}-free$ medium, $1mM\;H_2O_2$ still enhanced the intracellular $Ca^{2+}$ level. $Ca^{2+}$ entry tested using manganese quenching technique was not affected by perfusion of $1mM\;H_2O_2$. On the other hand, $10mM\;H_2O_2$ induced more rapid $Ca^{2+}$ accumulation and facilitated $Ca^{2+}$ entry from extracellular fluid. $Ca^{2+}$ refill into intracellular $Ca^{2+}$ store and inositol 1,4,5-trisphosphate ($1{\mu}M$)-induced $Ca^{2+}$ release from $Ca^{2+}$ store was not affected by $1mM\;H_2O_2$ in permeabilized cells. $Ca^{2+}$ efflux through plasma membrane $Ca^{2+}-ATPase$ (PMCA) was markedly blocked by $1mM\;H_2O_2$ in thapsigargin-treated intact acinar cells. Antioxidants, either catalase or dithiothreitol, completely protected $H_2O_2-induced$ $Ca^{2+}$ accumulation through PMCA inactivation. From the above results, we suggest that excessive production of $H_2O_2$ under pathological conditions may lead to cytosolic $Ca^{2+}$ accumulation and that the primary mechanism of $H_2O_2-induced$ $Ca^{2+}$ accumulation is likely to inhibit $Ca^{2+}$ efflux through PMCA rather than mobilize $Ca^{2+}$ ions from extracellular medium or intracellular stores in mouse parotid acinar cells.

• Molecular & Cellular Toxicology
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• 제2권4호
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• pp.236-243
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• 2006

Microarray analysis of gene expression has become a powerful approach for exploring the biological effects of drugs, particularly at the stage of toxicology and safety assessment. Acetaminophen (APAP) has been known to induce necrosis in liver, but the molecular mechanism involved has not been fully understood. In this study, we investigated gene expression changes of APAP using microarray technology. APAP was orally administered with a single dose of 50 mg/kg or 500 mg/kg into ICR mice and the animals were sacrificed at 6, 24 and 72 h of APAP administration. Serum biochemical markers for liver toxicity were measured to estimate the maximal toxic time and hepatic gene expression was assessed using high-density oligonucleotide microarrays capable of determining the expression profile of >30,000 well-substantiated mouse genes. Significant alterations in gene expression were noted in the liver of APAP-administered mice. The most notable changes in APAP-administered mice were the expression of genes involved in apoptosis, cell cycle, and calcium signaling pathway, cystein metabolism, glutatione metabolism, and MAPK pathway. The majority of the genes upregulated included insulin-like growth factor binding protein 1, heme oxygenase 1, metallothionein 1, S100 calcium binding protein, caspase 4, and P21. The upregulation of apoptosis and cell cycle-related genes were paralleled to response to APAP. Most of the affected gene expressions were returned to control levels after 72 hr. In conclusion, we identified potential hepatotoxicity makers, and these expressions profiling lead to a better understanding of the molecular basis of APAP-induced hapatotoxicity.

• 한국조리학회지
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• 제19권5호
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• pp.100-109
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• 2013

본 연구는 성인 311명 탈모 모발의 19가지 미네랄 함량을 평균, 성별, 연령별, 모발의 화학적 시술 여부 등으로 나뉘어 분석하였다. 연구결과 모발 내 미네랄 원소의 평균함량은 모두 권장기준치 범주 안에 있었으므로 탈모에 영향을 미치지 않는 것으로 나타났으며, 남녀간 모발의 미네랄 함량 분석 결과 영양원소 중 나트륨(p<.01), 칼륨(p<.01), 세레륨(p<.001)은 남성이, 칼슘, 마그네슘, 구리, 망간은 여성이 높게 나타났다. 독성원소의 경우 수은(p<.001) 비소(p<.01) 안티몬(p<.001)은 남성에게서 더 많은 함량이 검출되었다. 연령별 미네랄 함량을 분석한 결과 칼륨(p<.05), 철(p<.01), 망간(p<.05), 크롬(p<.01), 수은(p<.01)이 연령이 증가할수록 함량이 통계적으로 유의하였다. 특히 수은의 경우 50대 이상의 연령에서 축적함량(1.2904ppm)이 권장 참고수치(<1.1ppm)보다 초과하여 나타났다. 또 자연 상태 모발과 화학적 시술(펌, 염색) 모발 간의 미네랄 함량 분석 결과 셀레늄(p<.01), 납(p<.05), 알루미늄(p<.05), 비소(p<.01)등이 자연 상태 모발에서 함량이 높았으며, 칼슘(p<.001), 마그네슘(p<.001), 망간(p<.01)등은 염색이나 퍼머넌트를 한 모발에서 함량이 높게 나타났다. 이러한 연구 결과를 토대로 미네랄 함량의 과다 축적 및 미달이 탈모에 직접적인 영향을 미치지 않았으나 일부 중금속 경우는 남성들의 탈모에 다소 영향을 미치는 것을 알 수 있었으며, 이러한 선행 연구를 바탕으로 한 다음 연구에서는 이 자료가 비교분석 기초 자료로 활용될 것으로 사료된다.

• 한국식생활문화학회지
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• 제23권1호
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• pp.33-40
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• 2008

Accuracy of dietary assessment depends on correct estimation of quantity as well as correct data on composition of the products. Milk and soymilk were considered quite homogeneous in items of package size and composition. One serving size of fluid milk and soymilk is considered 200 mL but there are products with different amounts on the market. This study was conducted to investigate variations of amounts and composition of fluid milk and soymilk products of one portion siz on Korean market. Twenty-nine milk products were purchased and categorized into 8 groups-regular, low-fat, skim, chocolate, strawberry-flavored, banana-flavored, and black soybean-added. Sixteen fluid soymilk products were purchased and categorized into 4 groups-regular, infant, black sesame or black soybean added and others. Actual volume of each product was measured by mass cylinder and compositions of major nutrients on the package were compared to the values in the most widely used nutrient DB in Korea. Amounts of milk specified on the package of purchased products were 182.3-318.5 ml, the largest being banana-flavored milk. Amounts of soy milk were 184.3-240.5 mL, the largest being regular soymilk. Measured amount of each products were close to the amount on the package (<5%). Contents of macronutrients on the package were different from the food composition table in several products. The amounts of calcium varied greatly among the products due to the popularity of adding calcium to milk and soymilk products recently. These variations in the amount and contents of major nutrients in milk and soymilk products can lead to considerable error to the results of dietary assessment unless the amount and the composition of each product are regularly updated in the food composition table whenever the new products are introduced in the market.