• Journal of the Korean Ceramic Society
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• v.30 no.12
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• pp.1071-1079
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• 1993

Interaction of alkali oxides and SO3 and C3S formation and microstructure was studied using K2CO3 and Na2CO3 as alkali sources and (NH4)2SO4 for SO3. When SO3/K2O=1.43 as mole ratio, K2O and SO3 react to form K2SO4, this phase is immiscible with other oxide melt and thus could not affect C3S formation as well as its microstructure. In a condition of SO3/K2O 1, C3S crystals were round and grown in a much larger size. With addition of Na2O and SO3 by only 1wt% each, C3S formation was strongly hindered. Since C2S was stabilized by Na+ and SO4-2, it could not react to give C3S formation. However in the condition of SO3/Na2O=1.43, a little amount of C3S was formed. It is considered that small amount of Na2SO4 was formed, this phase was immiscible with clinker liquid, and the C3S crystals were formed locally in the liquid part of relatively low Na2O and SO3 compositions. These crystals had irregular and rough surfaces and contained more inclusions than those grown from K2O.SO3 system.

• Journal of Convergence for Information Technology
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• v.11 no.5
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• pp.199-205
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• 2021

This study was done to evaluate the dermatoxicity of zinc sulfate (ZnSO4) and the protective effect of Rubus parvifolius L. (RP) extract on cytotoxicity of ZnSO4, mordant in cultured SK-MEL-3 cells. For this study, it was done an antioxidative effect as DPPH-radical scavenging ability as well as the diminutive ability of total melanin with cell viability. ZnSO4 significantly decreased cell viability in dose-dependently, and it was mid-toxic. The ascorbic acid significantly increased cell viability damaged by ZnSO4-induced cytotoxicity. In the protective effect of RP extract on ZnSO4-induced cytotoxicity, RP extract significantly increased cell viability compared with ZnSO4-treated group, and also it showed both the DPPH-radical scavenging ability and the decrease of total amount of melanin. From these findings, the cytotoxicity of ZnSO4 is correlated with oxidative stress, and also RP extract effectively protected ZnSO4-induced cytotoxicity via antioxidative effect such as DPPH-radical scavenging ability with the whitening effect by the decrement of total amount of melanin. Conclusively, the natural ingredients like RP extract may be a useful agent for the improvement of antioxidative and whitening effects

• Journal of the Korean Ceramic Society
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• v.30 no.7
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• pp.527-534
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• 1993

The phenomena that excess sulfate hindred the C3S formation in the presence of clinker liquid phase were investigated. In the case of (NH4)2SO4, assuming SO3 atmospheric condition, sulfate stabilized C2S and was enriched at the surface of C2S grains, so C2S was prevented from being dissolved into clinker melt. CaSO4 showed the similar aspect with (NH4)2SO4, however, the prevention of C3S formation by CaSO4 took more influence that C2AS and C4A3 were formed below 100$0^{\circ}C$, and remained upto clinkering temperature, 145$0^{\circ}C$, thus these intermediate phases caught CaO which would participate the C3S formation.

• Journal of the Korean Ceramic Society
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• v.20 no.4
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• pp.297-304
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• 1983

In this study a Comparative investigation of the effect of $K_2SO_4$ and $CaSO_4$ on the formation of calcium silicate was made. $K_2SO_4$ had little effect on C3S formation. More than 4.0wt% of CaSO4 hindered the reaction of $C_2S$ and CaO so $C_3S$ formation was restrained by forming the reaction rim around $C_2S$ Particles. And activation energy for $C_3S$ formation was calculated around to be 40kcal/mol irespective of the amount of $K_2SO_4$.

• Journal of the Korean Ceramic Society
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• v.30 no.1
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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.

• Journal of Plant Biology
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• v.14 no.2
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• pp.1-6
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• 1971

When germination beds of carrot seeds were treated with either 0.01M or 0.05M concentrations of Ca(NO3)2, CaSO4, MgSO4, K2SO4 and KH2PO4, an acceleration in the germination rate was observed in the groups treated with 0.01M KH2PO4 and 0.05M MgSO4 and 0.05M Ca(NO2)3. In earlier work by the author with acetone a similar result was observed and reported. The pH range in these experiments was maintained between 5.0 and 6.0. It was found that the groups treated with 0.05M K2SO4, 0.05M Ca(NO3)2, 0.05M Ca(NO3)2, 0.05M MgSO4, 0.01M KH2PO4, 0.01M Ca(NO3)2 germinated earlier than the control group. The acceleration of the germintion rate varied with the inorganic compounds used in the following descending order; 0.01M KH2PO4, 0.05M Ca(NO3)2, 0.05M K2SO4, 0.05M CaSO4 and 0.05M KH2PO4. As a result of these expriments, it occurs to the author that in the germination of carrot seeds some inorganic compounds appear to activate the osmotic function of carrot seeds causing acceleration in the germination rate.

• Resources Recycling
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• v.7 no.5
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• pp.33-40
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• 1998

The formation reation of anhydrite (CaSO$_{4}$) depends upon the amount and velocity of the SO$_{3}$(g) and CaO(s) produced in the process of the thermal decomposition of alunite[K$_{2}SO_{4}{\cdot}Al_{2}(SO_{4})_{3}{\cdot}4Al(OH)_{3}$] and limestone (CaCO$_{3}$) respectively. Therefore, this study had carried out to investigate the amount and velocity of SO$_{3}$(g) produced by roasting alunite and pyrolytic materials. In air, alunite was transfouned into KAl(SO$_{4})_{2}$ and Al$_{2}O_{3}$ by dehydration at 500~580$^{\circ}C$. The dehydration velocity of alunite was found to be kt=(1-(1-${\alpha})^{1/3})^{2}$, the activation energy, 73.01 kcal/mol. SO$_{3}$(g) ware slowly produced by the thermal decomposition of KAl(SO$_{2})_{2}$, at 580~700$^{\circ}C$, rapidly, at 700~780$^{\circ}C$, The pyrolysis velocity of KAl(SO$_{4})_{2}$ was found to be kt=1-(1-${\alpha})^{1/1}$; activation energy, 66.84kcal/mol. The SiO$_{2}$ and kaolinite in alunite ore scarcely affected the temperature and velocity in which SO$_{3}$(g) were produced.

• Journal of the Mineralogical Society of Korea
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• v.23 no.2
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• pp.117-124
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• 2010

The sorption of $AsO_4,\;SeO_3,\;CrO_4$ on schwertmannite and thermal analysis of sorbed samples were carried out. The results of sorption experiments showed that sorption characteristics of those three oxyanions on schwertmannite can be divided into two groups. The extent of sorption of $AsO_4$ and $SeO_3$ were 100% at up to 1 mM solution concentration, and they increased no more significantly. This can be interpreted as $AsO_4$ and $SeO_3$ substituting $SO_4$ in schwertmannite strucure by the ratio of 1 : 1. The extent of the sorption of $CrO_4$ was much lower than those of other two oxyanions. Thermal analysis was performed using two kinds of sorbed samples at 0.1 and 1.25 mM concentrations. The results of the thermal analysis showed that the samples sorbed by three different oxyanions have different thermal characteristics. The samples sorbed by $AsO_4$ showed smaller weight loss around $600^{\circ}C$ than the original loss of pure schwertmannite, and it is attributed to the substitution of $AsO_4$ for $SO_4$, which was caused by the loss of $SO_4$, than pure schwertmannite due to the substitution of $SO_4$ by $AsO_4$. It also showed additional weight loss around $600^{\circ}C$ due to the decomposition of $AsO_4$ at that temperature. The weight loss of samples sorbed by $SeO_3$ started at slightly lower temperature than that sorbed by $SO_4$ and kept that loss at wider temperature range, probably indicating that the decomposition of $SeO_3$ occurs at slightly lower temperature. However, for the samples sorbed by $CrO_4$, the weight loss caused by the decomposition of $SO_4$ was also smaller and there was no additional weight loss at higher temperature due to the thermal stability of $CrO_4$, indicating that $SO_4$ was also substituted by $CrO_4$ in schwertmannite. Sorption experiment and thermal analysis indicate that $CrO_4$ sorbs on schwertmannite by substiuting $SO_4$, but the affinity to $SO_4$ or instability of $CrO_4$ in scwertmannite structure probably prohibit perfect 1 : 1 substitution.

• Journal of radiological science and technology
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• v.16 no.1
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• pp.107-115
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• 1993

In this study, to develop highly sensitive radiation sensors, $CaSO_4$ : Tm phosphors and its disc-type TLD elements embedded PTFE(polytetrafluoroethylene) are fabricated. The highest sensitivity of $CaSO_4$ : Tm phosphors is obtained when phosphors have been doped with 0.5mol % Tm and sintered in atmosphere at $600^{\circ}C$ for two hours. Fabricated disc-type elements are made from a homogeneous mixture of phosphors and PTFE powder. They are first cold-pressed and then polymerized at $370^{\circ}C$ in air for one hour. The dose dependence of the prepared $CaSO_4$ : Tm TLD radiation sensors is linear within the range of $100{\mu}Gy{\sim}10Gy$ for X-rays and ${\gamma}-rays$. The response of $CaSO_4$ : Tm to 30keV X-rays is ten times higher than that of 1.25MeV $^{60}Co\;{\gamma}-rays$. The fading rate of the main peak is about 2% per a month. The spectral peaks of TL emission spectrum are at about 350nm and 475nm. The $CaSO_4$ : Tm TLD radiation sensors prepared in this work may be used as radiation dosimeter for personal and environmental monitoring because of their high sensitivity and little fading.

• Journal of Microbiology and Biotechnology
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• v.5 no.2
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• pp.96-99
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• 1995

Addition of l00mM $MgSO_4$ to a cell culture after 54 hours resulted in a 2.4-fold increase in the sisomicin titre compared to a control to which no $MgSO_4$ was added, and a considerable amount of intracellular sisomicin was liberated outside the cells. The occurrence of product inhibition in fermentation was confirmed by a reduction in net sisomicin production with increasing amounts of added sisomicin without addition of $MgSO_4$. All added sisomicin was bound to sisomicin-free cells in the absence of $MgSO_4$, whereas approximately 40% of added sisomicin was bound with the addition of l00mM $MgSO_4$. Under conditions of no enzmye synthesis, maintained by adding chloramphenicol to exclude product repression, sisomicin was produced in the presence of 100 mM $MgSO_4$ but little sisomicin was produced in the absence of $MgSO_4$.