• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.6
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• pp.601-607
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• 2002

The present study was designed to examine how sea tangle intake contributes to the content of bone calcium and breaking force of femur with growing female rats. Weaned rats were fed on experimental diets consisting in four levels of sea tangle powder; $0\%$ (control), $0.5\%$, $1.0\%$ and $1.5\%$ for 4 and 8 weeks. Body weight gain and feed intake were not significantly affected by added amount of sea tangle. Bone breaking strength, ash content and calcium levels of the femur of rats fed on diets with sea tangle were higher than those of control groups (p<0.05). But moisture content weight and length of femur did not show any significant difference among groups. TP, ALB, TC, TG, AIP, osteocalcin, GOT and GPT levels in serum did not show any significant difference through the total feeding period but calcium and phosphorus contents of serum increased with increase in feeding period, significantly in $0.05\%$ level by added amounts of sea tangle. Calcium levels in feces increased significantly (P<0.05), but ash levels were not changed significantly by added amount of sea tangle. We could expect from this results that the ingestion of sea tangle (Kjellemaniella crassifolia) could be helpfull to increase bone calcium content and calcium absorption as well as to intensify the femur stength and to increase the calcium content of rats.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.1
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• pp.1-9
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• 2014

Calcium (Ca) and phosphorus (P) are minerals that have important physiological functions in the body. For formulation of diets for pigs, it is necessary to consider an appropriate Ca:P ratio for an adequate absorption and utilization of both minerals. Although both minerals are important, much more research has been conducted on P digestibility than on Ca digestibility. Therefore, this review focuses on aspects that are important for the digestibility of Ca. Only values for apparent total tract digestibility (ATTD) of Ca have been reported in pigs, whereas values for both ATTD and standardized total tract digestibility (STTD) of P in feed ingredients have been reported. To be able to determine STTD values for Ca it is necessary to determine basal endogenous losses of Ca. Although most Ca is absorbed in the small intestine, there are indications that Ca may also be absorbed in the colon under some circumstances, but more research to verify the extent of Ca absorption in different parts of the intestinal tract is needed. Most P in plant ingredients is usually bound to phytate. Therefore, plant ingredients have low digestibility of P due to a lack of phytase secretion by pigs. During the last 2 decades, inclusion of microbial phytase in swine diets has improved P digestibility. However, it has been reported that a high inclusion of Ca reduces the efficacy of microbial phytase. It is possible that formation of insoluble calcium-phytate complexes, or Ca-P complexes, not only may affect the efficacy of phytase, but also the digestibility of P and Ca. Therefore, Ca, P, phytate, and phytase interactions are aspects that need to be considered in Ca digestibility studies.

• Journal of the Korean Ceramic Society
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• v.31 no.7
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• pp.695-702
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• 1994

Current study was undertaken to explain the structural evolution and corresponding changes in the properties of calcium aluminate glasses with the variation of SiO2 doping concentration. Calcium aluminate glasses in the compositional ranges of (100-x)(0.6CaO+0.4Al2O3)+xSiO2(where x=0~60) were fabricated. DTA analysis confirmed an anomalous behavior in glass transition temperature (Tg) with the maximum of 887$^{\circ}C$ and minimum of 859$^{\circ}C$ when x=5 and 50, respectively. densities and refractive indices monotonically decreased with increasing SiO2 content and IR transmitting cutoff shifted to shorter wavelength side when the amount of added SiO2 exceeded 5 mole%. IR fundamental vibration absorption peaks showed the change that NBOs were inclined to SiO4 tetrahedron in the low-silica region and NBO per SiO4 tetrahedra changed from 2 to 0 with increasing silica content. Based on the analysis of IR fundamental vibration absorption peaks, the model of the structural change can be proposed in three step: 1) SiO4 scavenged the NBOs located at AlO4-tetrahedra, which resulted in the increased of Tg values, 2) NBOs located in the main network again with a decrease in Tg, and 3) dominated by the decrease in the relative amount of NBOs in the glass system, where Tg re-increased.

• Journal of the Korea Institute of Building Construction
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• v.14 no.3
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• pp.230-236
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• 2014

This study was carried out to investigate the manufacturability of artificial lightweight aggregate as a way to recycle basalt powder sludge, which is a waste produced during the manufacturing process of basalt in Jeju. Powdered waste glasses and calcium carbonate are used to improve the characteristics of manufactured artificial lightweight aggregate. Especially, considering the complex factors of basalt powder sludge, powdered waste glasses, and sintering method, the amount of calcium carbonate is appropriate at the 9 wt.% in order to improve the intumescent of lightweight aggregate. Also, the amount of powdered waste glasses is effective with using less than 50 wt.% and applying the direct sintering method at the same time on decreasing the absorption of lightweight aggregate. Furthermore, in order to manufacture artificial lightweight aggregate of high quality with a low specific gravity and low water absorption, it is considered to be more effective to apply the direct sintering method after the surface of artificial lightweight aggregate is covered with powdered waste glasses.

• The Korean Journal of Physiology and Pharmacology
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• v.22 no.3
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• pp.277-289
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• 2018

The exponential increase in the use of mobile communication has triggered public concerns about the potential adverse effects of radiofrequency electromagnetic fields (RF-EMF) emitted by mobile phones on the central nervous system (CNS). In this study, we explored the relationship between calcium channels and apoptosis or autophagy in the hippocampus of C57BL/6 mice after RF-EMF exposure with a specific absorption rate (SAR) of 4.0 W/kg for 4 weeks. Firstly, the expression level of voltage-gated calcium channels (VGCCs), a key regulator of the entry of calcium ions into the cell, was confirmed by immunoblots. We investigated and confirmed that pan-calcium channel expression in hippocampal neurons were significantly decreased after exposure to RF-EMF. With the observed accumulation of autolysosomes in hippocampal neurons via TEM, the expressions of autophagy-related genes and proteins (e.g., LC3B-II) had significantly increased. However, down-regulation of the apoptotic pathway may contribute to the decrease in calcium channel expression, and thus lower levels of calcium in hippocampal neurons. These results suggested that exposure of RF-EMF could alter intracellular calcium homeostasis by decreasing calcium channel expression in the hippocampus; presumably by activating the autophagy pathway, while inhibiting apoptotic regulation as an adaptation process for 835 MHz RF-EMF exposure.

• International Journal of Highway Engineering
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• v.17 no.2
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• pp.99-105
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• 2015

PURPOSES: In this study, alkali-activated blast-furnace slag (AABFS) was investigated to determine its capacity to absorb carbon dioxide and to demonstrate the feasibility of its use as an alternative to ordinary Portland cement (OPC). In addition, this study was performed to evaluate the influence of the alkali-activator concentration on the absorption capacity and physicochemical characteristics. METHODS: To determine the characteristics of the AABFS as a function of the activator concentration, blast-furnace slag was activated by using calcium hydroxide at mass ratios ranging from 6 to 24%. The AABFS pastes were used to evaluate the carbon dioxide absorption capacity and rate, while the OPC paste was tested under the same conditions for comparison. The changes in the surface morphology and chemical composition before and after the carbon dioxide absorption were analyzed by using SEM and XRF. RESULTS: At an activator concentration of 24%, the AABFS absorbed approximately 42g of carbon dioxide per mass of paste. Meanwhile, the amount of carbon dioxide absorbed onto the OPC was minimal at the same activator concentration, indicating that the AABFS actively absorbed carbon dioxide as a result of the carbonation reaction on its surface. However, the carbon dioxide absorption capacity and rate decreased as the activator concentration increased, because a high concentration of the activator promoted a hydration reaction and formed a dense internal structure, which was confirmed by SEM analysis. The results of the XRF analyses showed that the CaO ratio increased after the carbon dioxide absorption. CONCLUSIONS : The experimental results confirmed that the AABFS was capable of absorbing large amounts of carbon dioxide, suggesting that it can be used as a dry absorbent for carbon capture and sequestration and as a feasible alternative to OPC. In the formation of AABFS, the activator concentration affected the hydration reaction and changed the surface and internal structure, resulting in changes to the carbon dioxide absorption capacity and rate. Accordingly, the activator ratio should be carefully selected to enhance not only the carbon capture capacity but also the physicochemical characteristics of the geopolymer.

• Journal of Pharmaceutical Investigation
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• v.27 no.1
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• pp.57-64
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• 1997

$Amino-{\beta}-lactam$ antibiotics are absorbed by the dipeptide transporter in the small intestine. These uptakes are coupled to a proton influx. The inward proton gradient is partly induced by the $Na^+/H^+$ exchanger and calcium ion is involved in control of this antiport. Interaction between ampicillin which is one of the $Amino-{\beta}-lactam$ antibiotics and nifedipine which is one of calcium channel blocking agents was studied in rats in vivo and with rabbit jejunum mounted on the Sweetana/Grass diffusion cells in vitro. Bioavailability of ampicillin was increased significantly when nifedipine was co-administered orally in rats. There were no differences in the distribution phase and the elimination phase when ampicillin was given either alone or with nifedipine intravenously. Conditions for in vitro experiments were determined. The lift rate of $O_2/CO_2$ gas was controlled to 3 bubbles/sec and ampicillin was stable in the Kreb's buffer at pH 6.0. Absorption of ampicillin was the greatest when the completely-stripped serosal membrane was used. Transport of ampicillin from mucosal to serosal side in the rabbit jejunum was enhanced by 32% in the presence of nifedipine (p=0.059). Above results suggest that nifedipine might increase the plasma level of ampicillin via the improved absorption in the intestine rather than the reduction in the elimination or/and alteration in the distribution.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.6
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• pp.80-87
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• 2015

In this study, several properties of mortars made with calcium aluminate cement (CAC) such as hydrated products, strength characteristics, absorption, surface electric resistivity and chloride ions penetration resistance were experimentally investigated. The properties of CAC mortars were compared to those of ordinary portland cement (OPC) mortars. From the test results, it was found that the main hydrated products for CAC mortars were of $C_2AH_8$ and $CAH_{10}$, while CH, ettringite and calcite for OPC mortars. The surface electric resistivity and chloride ions penetration resistance of CAC mortars were significantly beneficial compared to those of OPC mortars. However, it should be noted that the absorption properties of CAC mortars were negatively examined. Thus, it needs to have more study for the improvement of surface absorption of CAC matrices. In addition, the combined mixture of CAC and OPC were ineffective to improve some performances of mortars.

• Journal of the Korean Society of Food Science and Nutrition
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• v.25 no.6
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• pp.1016-1023
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• 1996

The effect of dietary calcium levels, 50%, 100%, and 200% of requirement, on iron utilization was evaluated in 30 Sprague-Dawley female rats by use of balance study for 3 weeks. In the results of this study, there were no significant difference in feed intake, body weight gain, hemoglobin level, hematocrit, calcium and iron levels in serum and tissues across the groups supplemented different calcium levels. Calcium content in kidney of high-calcium group was significantly higher than that of other groups. Urinary and fecal calcium excretions increased as the level of dietary calcium was increased. With increasing levels of dietary calcium, daily calcium retention was accelerated, but daily calcium retention rate was diminished. Iron intake was significantly higher in adequate-calcium group than that in low-calcium or high-calcium group. Urinary and fecal iron excretions were significantly lower in low-calcium group than those in adequate-calcium or high-calcium group. Apparent retention and retention rate estimated by intake, urinary and fecal excretions of iron were significantly lower in high-calcium group t]lan those in low-calcium or adequate-calcium group. These results suggest that taking dietary calcium supplements reduce the absorption of dietary iron.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.450-450
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• 2003