• Korean Journal of Materials Research
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• v.25 no.2
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• pp.75-80
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• 2015

The carbon dioxide($CO_2$) released while producing building materials is substantial and has been targeted as a leading contributor to global climate change. One of the most typical method to reducing $CO_2$ for building materials is the addition of slag and fly ash, like pozzolan material, while another method is reducing $CO_2$ production by carbon negative cement development. The MgO-based cement was from the low-temperature calcination of magnesite required less energy and emitted less $CO_2$ than the manufacturing of Portland cements. It is also believed that adding reactive MgO to Portland-pozzolan cements could improve their performance and also increase their capacity to absorb atmospheric $CO_2$. In this study, the basic research for magnesia cement using $MgCO_3$ and magnesium silicate ore (serpentine) as main starting materials, as well as silica fume, fly ash and blast furnace slag for the mineral admixture, were carried out for industrial waste material recycling. In order to increase the hydration activity, $MgCl_2$ was also added. To improve hydration activity, $MgCO_3$ and serpentinite were fired at $700^{\circ}C$ and autoclave treatment was conducted. In the case of $MgCO_3$ as starting material, hydration activity was the highest at firing temperature of $700^{\circ}C$. This $MgCO_3$ was completely transferred to MgO after firing. This occurred after the hydration reaction with water MgO was transferred completely to $Mg(OH)_2$ as a hydration product. In the case of using only $MgCO_3$, the compressive strength was 3.5MPa at 28 days. The addition of silica fume enhanced compressive strength to 5.5 MPa. In the composition of $MgCO_3$-serpentine, the addition of pozzolanic materials such as silica fume increased the compression strength. In particular, the addition of $MgCl_2$ compressive strength was increased to 80 MPa.

• Bulletin of the Korean Chemical Society
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• v.20 no.5
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• pp.535-538
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• 1999

Five coordinated water-soluble iridium(l) complex, IrH(CO)(TPPTS)3 (1) (TPPTS = P(m-C6H4SO3Na)3-xH2O) has been prepared from the reaction of IrCl3·3H2O with TPPTS and HCHO in H2O/EtOH solution. Complex 1 catalyzes the hydration of nitrites (RC ≡ N, R = CH3, CICH2, CH3(CH2)4, Ph) in aqueous solution to give the corresponding amides (RCONH2) at 100℃. The hydration of unsaturated nitrites (R'C ≡ N, R'=CH3CH=CH, CH3OCH=CH, trans-PhCH=CH, CH2=C(CH3)) takes place regioselectively on-C ≡ N group to give unsaturated amides (R'CONH2) leaving the olefinic group intact. The yields of the amides seem to be depending on the electrophilicity of the carbon of nitrile: The more the electron withdrawing ability of the substituents on nitrites, the more amides are obtained. The hydration of dinitriles (NC-R-CN, R=(CH2)4, (CH2)6) with complex 1 initially gives mono-hydration products (NC-R-CONH2) which are slowly hydrated further to give dihydration products (H2NCO-R-CONH2). The hydration of 1,4-dicyanobutane has been found to be somewhat faster than that of 1,6-dicyanohexane.

• Archives of Pharmacal Research
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• v.13 no.1
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• pp.43-50
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• 1990

Conformational free energy calculations using an empirical potential function (ECEPP/2) and hydration shell model were carried out on the four-4-aminodiphenyl sulfone analogues of 4, 4'-diamino-2' methyldiphenyl sulfone, 4, 2', 4-triaminodiphenyl sulfone, 4, 4'-diaminodiphenyl sulfone, and 4-aminodiphenyl sulfone as antibacterial agents on Mycobacterium lufu. The conformational energy was minimized from starting conformations which included possible combinations of torsion angles in the molecule. The conformational entropy change of each conformation was computed using a harmonic approximation. To understand the hydration effect on the conformation of the molecule in aqueous solution, the contributions of water-accessible volume and the hydration free energy of each group or atom in the lowest-free-energy conformation was calculated and compared each other. From comparison of the computed lowest-free-energy conformations of four analogues with their antibacterial activities, it is known that the conformation and the hydrophobicity of sulfonyl group and its adjacent carbon atom in each compound are the essential factors to show the strong antibacterial activity.

• YAKHAK HOEJI
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• v.36 no.6
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• pp.518-528
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• 1992

To determine the optimal conformation of sulfonylureas, the correlation between conformation and hypoglycemic activity of the two sulfonylureas of tolbutamide and chlorpropamide as hypoglycemic agent was studied using an empirical potential function (ECEPP/2) and the hydration shell model in the unhydrated and hydrated states. The conformational energy was minimized from several starting conformations with possible torsion angles in each molecule. The conformational entropy change of each conformation was computed using a harmonic approximation. To understand the hydration effect on the conformation of the molecules in aqueous solution, the contribution of water-accessible volume of each group or atom in the lowest-free-energy conformation was calculated and compared each other. From comparison of the computed lowest-free-energy conformations of two sulfonylureas, it could be suggested that the hydration of sulfonylurea moiety is related to increase the hypoglycemic activity. From the calculation results, it was known that the conformational entropy is the major contribution to stabilize the low-free-energy conformations of two sulfonylureas in unhydrated state. Whereas, in hydrated state, the hydration free energy largely contributes to the total free energies of low-free-energy conformations of tolbutamide and conformational entropy contributes to stabilize the low-free-energy conformations of chlorpropamide. The torsion angles from phenyl ring to urea moiety of the low-free-energy conformations of the two sulfonylureas were shown the nearly regular trend. On the basis of these results, the conformation exhibiting the optimal hypoglycemic activity of sulfonylureas and the binding direction to pancreatic receptor site A could be predicted. Also, according to the side chain lengthening of urea moiety, tolbutamide showed various conformational change. Therefore, steric effect may be important factor in the interaction between sulfonylureas and the putative pancreatic receptor.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.5
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• pp.95-102
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• 2022

Recently, there has been a growing interest in reducing greenhouse gases in all industrial fields. In the construction industry, studies have been conducted for the use of high-volume fly ash concrete to replace cement with fly ash. Quantitative measurements of cement hydration and fly ash reactivity enable a clear understanding of the strength development mechanism of high-volume fly ash concrete. It is very difficult to describe the reactivity in a simple way because the hydration and pozzolanic reactions of cement paste containing fly ash are very complex and the composition of the hydration product cannot be accurately determined. This study investigated the hydration and mechanical properties of high volume fly ash (HVFA) cement according to the substitution rate of fly ash (FA). The hydration degree of cement and the reactivity of FA were evaluated through the selective dissolution method and the non-evaporable water content of the paste according to age. In addition, compressive strength was measured using HVFA mortar specimens according to age. As a result of the experiment, as the substitution rate of fly ash increased, the hydration degree of cement increased, but the reactivity of FA decreased.

• Applied Chemistry for Engineering
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• v.26 no.2
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• pp.128-131
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• 2015

Hydration of nitriles in the environmentally benign neutral conditions is the most economical and attractive way to produce amides. Substantial research works have been carried out to apply the solid metal oxides and transition metal supported catalytic systems to promote the hydration of nitriles. The most significant feature of these catalysts is the applicability to a wide range of substrates including aromatic, alicyclic, hetero-atomic, and aliphatic nitriles. These catalysts are also characterized by the easy isolation from the reaction mixture and the reusability while maintaining the high catalytic activity. This review accounts over the detailed survey of the metal oxide and solid supported metal catalysts for preparing amides from the hydration of nitriles.

• Journal of the Korean Ceramic Society
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• v.51 no.2
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• pp.115-120
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• 2014

Quicklime(CaO) is generally obtained through the calcination of limestone, the main component of which is calcium carbonate($CaCO_3$). Quicklime generates high-temperature heat when reacting with water, forming slaked lime($Ca(OH)_2$). The industrial sectors for limestone are determined by the hydraulic activity of slaked lime, which is obtained by measuring temperature changes during the hydration reaction. Accordingly, this study examined the different crystallographic characteristics of limestone as affected by the geological origins of the regions where the limestones were produced, and how these characteristics affected hydraulic activity. Six limestone samples were collected from the Jecheon and Cheongsong areas and the hydraulic activities were measured in accordance with KS E 3077. The results indicate that limestone produced in the Cheongsong area, recrystallized through metamorphism caused by hydrothermal alteration, hada larger grain size of calcite than that of the Jecheon area, and displays a tendency of changing to marble. Limestone from the Cheonsong area showed more radical reaction in the early stage of hydration compared to that ofthe Jecheon area. In addition, it was revealed that limestone having more impurities like $SiO_2$ have lower hydraulic activity.

• Proceedings of the SCSK Conference
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• 2003.09a
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• pp.98-141
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• 2003

Lip chapping is a serious cosmetics problem, though remedies other than moisturizing have not been proposed. We investigated changes in the surface configurations of lip corneocytes and increased CD activity and improved chapping severity. Our results suggest that lip chapping can be activities of desquamation-regulating proteinases associated with lip chapping. Using scanning electron microscopy, villus-like projections were observed on the inner surfaces of most corneocytes from normal lips, whereas those with flatter surface were predominant in chapped lips. Further, cell surface area increased with the severity of lip chapping. Cathepsin D (CD)-like and chymotrypsin-like proteinase, which are also present in skin as desquamation-regulating proteinases, were detected in lip corneocytes, though only CD activity was found to decrease in severely chapped lips. Hydration was also lower in areas of lip chapping. Sequential topical application of apricot extract essence characterized as similar to senile xerosis rather than dry skin such as winter xerosis, as it shows a delayed transition of corneocytes through the stratum corneum, and the reduced CD activity may be one of the mechanisms that is further decreased by low hydration. We propose that an enhancement of both CD activity and lip moisture may be effective to improve lip chapping.

• Proceeding of EDISON Challenge
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• 2014.03a
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• pp.103-113
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• 2014

Hydrophobicity is the key concept to understand the role of water in protein folding, protein self-assembly, and protein-ligand interaction. Conventionally, hydrophobicity of amino acids in a protein has been argued based on hydrophobicity scales determined for individual free amino acids, assuming that those scales are unaltered when amino acids are embedded in a protein. Here, we investigate how the hydrophobicity of constituent amino acids depends on the protein context, in particular, on the total charge and secondary structures of a protein. To this end, we compute and analyze the hydration free energy - free energy change upon hydration quantifying the hydrophobicity - of three short proteins based on the integral-equation theory of liquids. We find that the hydration free energy of charged amino acids is significantly affected by the protein total charge and exhibits contrasting behavior depending on the protein net charge being positive or negative. We also observe that amino acids in the central ${\beta}$-strand sandwiched by ${\beta}$-sheets display more enhanced hydrophobicity than free amino acids, whereas those in the ${\alpha}$-helix do not clearly show such a tendency. Our results provide novel insights into the hydrophobicity of amino acids, and will be valuable for rationalizing and predicting the strength of water-mediated interaction involved in the biological activity of proteins.

• KSBB Journal
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• v.9 no.3
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• pp.239-245
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• 1994

The effects of reaction temperature and the level of hydration(water activity) were studied for gas phase reactions of alcohol oxidase and alcohol dehydrogenase immobilized on DEAE-cellulose and controlled pore glass(CPG). Optimum reaction temperature zone of gas phase reaction was similar to that of aqueous phase reaction. The activity of alcohol oxidase increased dramatically and the stability decreased when the water activity was increased from 0.3 to 0.8. The apparent activation energies of the gas phase reaction decreased approaching the values obtained in the aqueous phase reaction as the water activity increased. In the both cases of alcohol oxidase and alcohol dehydrogenase, the rate constants of the gas phase reaction were lower than those of aqueous phase reaction by two orders of magnitude and these results could be correlated to the vapor-liquid equilibrium data of the substrate, ethanol.