• International Journal of Concrete Structures and Materials
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• 제8권4호
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• pp.289-299
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• 2014

Alkali-activated slag concretes are being extensively researched because of its potential sustainability-related benefits. For such concretes to be implemented in large scale concrete applications such as infrastructural and building elements, it is essential to understand its early and long-term performance characteristics vis-a'-vis conventional ordinary portland cement (OPC) based concretes. This paper presents a comprehensive study of the property and performance features including early-age isothermal calorimetric response, compressive strength development with time, microstructural features such as the pore volume and representative pore size, and accelerated chloride transport resistance of OPC and alkali-activated binder systems. Slag mixtures activated using sodium silicate solution ($SiO_2$-to-$Na_2O$ ratio or $M_s$ of 1-2) to provide a total alkalinity of 0.05 ($Na_2O$-to-binder ratio) are compared with OPC mixtures with and without partial cement replacement with Class F fly ash (20 % by mass) or silica fume (6 % by mass). Major similarities are noted between these binder systems for: (1) calorimetric response with respect to the presence of features even though the locations and peaks vary based on $M_s$, (2) compressive strength and its development, (3) total porosity and pore size, and (4) rapid chloride permeability and non-steady state migration coefficients. Moreover, electrical impedance based circuit models are used to bring out the microstructural features (resistance of the connected pores, and capacitances of the solid phase and pore-solid interface) that are similar in conventional OPC and alkali-activated slag concretes. This study thus demonstrates that performance-equivalent alkali-activated slag systems that are more sustainable from energy and environmental standpoints can be proportioned.

• Journal of Pharmaceutical Investigation
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• 제24권3호spc1호
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• pp.49-57
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• 1994

The objective of this study was to determine whether Pz-peptide, an enhancer of hydrophilic solute permeability in the intestine, could elevate the paracellular permeability of the cornea and conjunctiva in the pigmented rabbit. The in vitro penetration of four hydrophilic solutes, mannitol (MW 182), fluorescein (MW 376), FD-4 (FITC-dextran, 4 KDa), and FD-10 (FITC-dextran, 10 KDa) across the pigmented rabbit cornea and conjunctiva was studied either in the presence or absence of 3 mM enhancers. Drug penetration was evaluated using the modified Ussing chamber. The conjunctiva was more permeable than the cornea to all four markers. EDTA and cytochalasin B showed higher effects on marker transport than Pz-peptide, but Pz-peptide elevated the corneal transport of mannitol, fluoresein, and FD-4 by 50%, 26%, and 50%, respectively, without affecting FD-10 transport. Possibly due to the leakier nature of the conjunctiva, 3 mM Pz-peptide elevated the transport of only FD-4 by about 45%, without affecting the transport of other markers. Furthermore, the transport of Pz-peptide itself across the cornea and conjunctiva increased with increasing concentration in the 1-5 mM range, suggesting that Pz-peptide enhanced its own permeability, possibly by elevating paracellular permeability. Effects of ion transport inhibitors on Pz-peptide transport were then investigated. PZ-peptide penetration was not changed by mucosal addition of $10\;{\mu}M$ amiloride or $10\;{\mu}M$ hexamethylene amiloride, inhibiting serosal $Na^{+}$ exit by $100\;{\mu}M$ ouabain, or replacing $Na^{+}$ with choline chloride in the mucosal side buffer. These results seggested that Pz-peptide enhanced the paracellular permeability of rabbit cornea and conjunctiva and further indicate that ion transporters were not involved in the Pz-peptide induced elevation of paracellular marker permeability.

• 대한한방내과학회지
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• 제18권1호
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• pp.1-14
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• 1997

An experimental study was done to investigate the spontaneous movements to the isolated ileum with liquid extracts of Samchulgunbitang. Then the action of gastric ulcer, gastric-juice secretion, the free acidity, total acidity, pepsin output, the transport ability in the intestine, analgesic effect and sleeping time were measured. The following results were obtained; 1. As to the spontaneous movements in the isolated ileum, the effect of contraction against suppression was recognized. 2. The effects of contraction against suppression induced by acetylcholine chloride and barium chloride were recognized on the gastric funds strip significantly. 3. The preventive effect of Samchulgunbitang on the pylorus-lightedulcer in rat was recognized significantly. 4. The anti-ulcer effect of Samchulgunbitang was not recognized on the gastric ulcer caused by indomethacin. 5. The effects of decreasing on the secretion gastric juice, the free acidity, total acidity and pepsin output of Samchulgunbitang were recognized significantly. 6. The transport rate in the small intestine of Samchulgunbitang was decreased. 7. The transport rate in the large intestine of Samchulgunbitang was increased. 8. The analgesic effect of Samchulgunbitang caused by acetic acid was recognized significantly. 9. The sleeping time caused by pentobarbital-Na of Samchulgunbitang was prolonged significantly. According to the results, it is considered that the Samchulgunbitang has effects of gastric ulcer, chronic gastritis, hyper-acidity, gastroptosis such as abdominal discomfort, gastric acid, indigestion and anorexia.

• 대한지하수환경학회지
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• 제1권1호
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• pp.1-5
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• 1994

난지도 매립장 하부지반을 통한 오염이동 특성을 2차원 유한 요소 오염이동 모델을 이용하여 알아보고 부분적인 차폐벽을 매립장 주위에 설치하였을 경우 초래되는 매립장내 침출수 누적 효과를 유한 차분 지하수흐름 모델을 이용하여 분석하였다. 분석에 사용된 입력계수는 현장에서 측정된 오염농도 자료를 이용 검증한 후 향후 30년 동안에 한강변으로 누출될 수 있는 오염농도 변화를 분석하고 매립장내 침출 수두와 확산계수의 증가가 오염물 이동에 미치는 민감도를 알아보았다. 오염이동 해석 결과 한강주변의 난지도 매립장 침출수로 인한 염소이온농도 최대값은 1488 mg/l로서 매립장 패쇄후 17년만에 이루어지는 것으로 나타났다. 매립장내 침출수위와 확산계수의 변화는 모두 침출수 이동을 촉진하나 침출수위면이 증가 할수록 침출수 농도 증가 폭은 커져가는 반면 확산계수 증가에 대한 침출수 농도 증가 폭은 작아져서 일정 농도로 수렴하는 경향을 보였다.

• The Korean Journal of Physiology and Pharmacology
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• 제5권3호
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• pp.231-241
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• 2001

The mammalian cortical collecting duct (CCD) plays a major role in regulating renal NaCl reabsorption, which is important in $Na^+$ and $Cl^-$ homeostasis. The M-1 cell line, derived from the mouse cortical collecting duct, has been used as a mammalian model of the study on the electrolytes transport in CCD. M-1 cells were grown on collagen-coated permeable support and short circuit current $(I_{sc})$ was measured. M-1 cells developed amiloride-sensitive current $5{\sim}7$ days after seeding. Apical and basolateral addition of ATP induced increase in $I_{sc}$ in M-1 cells, which was partly retained in $Na^+-free$ or $Cl^--free$ solution, indicating that ATP increased $Na^+$ absorption and $Cl^-$ secretion in M-1 cells. $Cl^-$ secretion was mediated by the activation of apical cystic fibrosis transmembrane regulator (CFTR) chloride channels and $Ca^{2+}-activated$ chloride channels, but $Na^+$ absorption was not mediated by activation of epithelal sodium channel (ENaC). ATP increased cAMP content in M-1 cells. The RT-PCR analysis demonstrated that M-1 cells express $P2Y_2,\;P2X_3\;and\;P2Y_4$ receptors. These results showed that ATP regulates $Na^+$ and $Cl^-$ transports via multiple P2 purinoceptors on the apical and basolateral membranes in M-1 cells.

• Computers and Concrete
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• 제32권3호
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• pp.247-261
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• 2023

Due to the non-uniform distribution of meso-structure, the diffusion of chloride ions in concrete show the characteristics of characteristics of randomness and fuzziness, which leads to the non-uniform distribution of chloride ions and the non-uniform corrosion of steel rebar in concrete. This phenomenon is supposed as the main reason causing the uncertainty of the bearing capacity deterioration of reinforced concrete structures. In order to analyze and predict the durability of reinforced concrete structures under chloride environment, the random features of chloride ions transport in concrete were studied in this research from in situ meso-structure of concrete. Based on X-ray CT technology, the spatial distribution of coarse aggregates and pores were recognized and extracted from a cylinder concrete specimen. In considering the influence of ITZ, the in situ mesostructure of concrete specimen was reconstructed to conduct a numerical simulation on the diffusion of chloride ions in concrete, which was verified through electronic microprobe technology. Then a stochastic study was performed to investigate the distribution of chloride ions concentration in space and time. The research indicates that the influence of coarse aggregate on chloride ions diffusion is the synthetic action of tortuosity and ITZ effect. The spatial distribution of coarse aggregates and pores is the main reason leading to the non-uniform distribution of chloride ions both in spatial and time scale. The chloride ions concentration under a certain time and the time under a certain concentration both satisfy the Lognormal distribution, which are accepted by Kolmogorov-Smirnov test and Chi-square test. This research provides an efficient method for obtain mass stochastic data from limited but representative samples, which lays a solid foundation for the investigation on the service properties of reinforced concrete structures.

• 한국결정성장학회지
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• 제16권5호
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• pp.203-209
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• 2006

For $P_B=50,\;{\Delta}T=10K$, Ar=5, Pr=2.36, Le=0.015, Pe=1.26, Cv=1.11, the intensity of solutal convection (solutal Grashof number $Grs=3.44x10^4$) is greater than that of thermal convection (thermal Grashof number $Grt=1.81x10^3$) by one order of magnitude, which is based on the solutally buoyancy-driven convection due to the disparity in the molecular weights of the component A($Hg_2Cl_2$) and B(He). With increasing the partial pressure of component B from 10 up to 200 Torr, the rate is decreased exponentially. The convective transport decreases with lower g level and is changed to the diffusive mode at 0.1 $g_0$. In other words, for regions in which the g level is 0.1 $g_0$ or less, the diffusion-driven convection results in a parabolic velocity profile and a recirculating cell is not likely to occur. Therefore a gravitational acceleration level of less than 0.1 $g_0$ can be adequate to ensure purely diffusive transport.

• Applied Microscopy
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• 제17권1호
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• pp.29-46
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• 1987

To study hexavalent chromium effects on mitochondrial electron transport, the activities of electron transport enzymes and conformational change of mitochondria treated with $40{\mu}M$ of sodium dichromate ($Na_{2}Cr_{2}O_{7}\;2H_{2}O$) were investigated. And so were those of liver mitochondria isolated from mouse intraperitoneally injected with sodium dichromate, 40mg per kg body weight. On both treatment with chromium(VI), the activities of electron transfer enzymes (Complex I and IV) were increased to some extent and the ultrastructural transformation of mitochondria from a condensed to an orthodox conformation was inhibited under State IV respiration. These results represent' inhibitory effect of hexavalent chromium on electron transport without inhibiting electron transfer enzymes (Complex I and IV) in mitochondria. On intraperitoneal treatment with hexavalent chromium as sodium dichromate and trivalent chromium as chromic chloride, containing 37.5 mg of chromium per kg body weight, respectively, the activities of electron transfer enzymes of liver isolated from mouse with chromium(VI) was reduced, but that with chromium(III) was not affected. And with chromium(VI), all mice after 12 hours of treatment died, only after 6 hours survived. With chromium(III), however, all survived. This indicates that hexavalent chromium is more toxic than trivalent chromiumin mouse liver.

• 한국의류학회지
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• 제14권3호
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• pp.229-240
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• 1990

The purpose of this study was to investigate the effect of hydrophilicity of the fiber on the water vapor transport properties of the fabric by using double layered fabrics of natural and synthetic fibers such as cotton, wool, nylon, dacron, orlon and polypropylene. Wickability and absorption rate were measured to determine the absorbancy of the fabrics. Dynamic and steady state water vapor transport properties were measured by cobaltous chloride method and evaporation method, respectively. Absorption was in the order of orlon> cotton > wool > nylon > polypropylene > dacron. Dynamic surface wetness of synthetic fabrics were faster than that of natural fabrics. For the double layered fabrics, higher water vapor transport was resulted when the natural fabric was exposed to lower vapor pressure and synthetic fabric was exposed to higher vapor pressure than when the fabrics were layered the other way around. Opposite result was obtained for orlon, which suggested that when the fabric of high absorbancy is exposed to the environment and lower absorbancy is to the skin, higher water vapor transpont could be resulted.

• 대한약침학회지
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• 제4권2호
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• pp.49-56
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• 2001

This study was undertaken to determine whether Scutellaria baicalensis Georgi (SbG) extract exerts the protective effect against $HgCl_2$-induced alterations in membrane transport function in rabbit renal cortical slices. The slices were treated with 0.1 mM $HgCl_2$ for 60 min at $37^{\circ}C$. $HgCl_2$ caused an inhibition in PAH uptake by renal cortical slices. Such an effect was accompanied by depressed $Na^+-K^+$-ATPase activity and ATP depletion. SbG prevented $HgCl_2$-induced inhibition of PAH uptake in a dose-dependent manner at the concentration ranges of 0.01-0.1%. $HgCl_2$-induced inhibition of $Na^+-K^+$-ATPase activity and ATP depletion were significantly prevented by 0.05% SbG. These results suggest that SbG prevents $HgCl_2$-induced alterations in membrane transport function in rabbit renal cortical slices. Such protective effects of SbG may be attributed to inhibition of peroxidation of membrane lipid.