• Geomechanics and Engineering
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• v.12 no.5
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• pp.803-813
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• 2017

This study discussed the possible optimization of enzyme-mediated calcite precipitation (EMCP) as a soil-improvement technique. Magnesium chloride was added to the injection solution to delay the reaction rate and to improve the homogenous distribution of precipitated minerals within soil sample. Soil specimens were prepared in 1-m PVC cylinders and treated with the obtained solutions composed of urease, urea, calcium, and magnesium chloride, and the mineral distribution within the sand specimens was examined. The effects of the precipitated minerals on the mechanical and hydraulic properties were evaluated by unconfined compressive strength (UCS) and permeability tests, respectively. The addition of magnesium was found to be effective in delaying the reaction rate by more than one hour. The uniform distribution of the precipitated minerals within a 1-m sand column was obtained when 0.1 mol/L and 0.4 mol/L of magnesium and calcium, respectively, were injected. The strength increased gradually as the mineral content was further increased. The permeability test results showed that the hydraulic conductivity was approximately constant in the presence of a 6% mineral mass. Thus, it was revealed that it is possible to control the strength of treated sand by adjusting the amount of precipitated minerals.

• Archives of Pharmacal Research
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• v.19 no.2
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• pp.106-111
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• 1996

Alginate microspheres were prepared by the emulsification process as a drug delivery system of ampicillin sodium (AMP-Na). The preparation parameters such as the concentration of calcium chloride, the stirring time and the amount of AMP-NA were investigated. The alginate microspheres containing hydroxypropylmethylcellulose (HPMC) were found to be generally spherical, discrete and had smoother surfaces when compared to without HPMC. However, there was no significant difference in the release profile of AMP-NA from alginate microspheres prepared with or without HPMC. The concentration of calcium chloride solution and the stirring time in the preparation of alginate microspheres influenced the aggregation of alginate microspheres. The amount of AMP-NA in alginate microspheres influenced the surface morphology and the practical drug content in microspheres.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.3 no.1
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• pp.32-37
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• 2002

Ca$^{2+}$ plays an important the in firmness retention of plant tissues. In this study, effect of CaCl$_2$on extention of shelf-life of kakdugi, and its effective conditions of addition were determined. The rates of pH decrease, acidity increase and mechanical texture decrease during fermentation wire reduced by the addition of CaCl$_2$. Furthermore, sensory characteristics of kakdugi such as crispness, sourness and overall taste were improved. Addition of 0.1% CaCl$_2$in brine solution and 0.05% CaCl$_2$to seasoning was the most effective condition to extend shelf-life of kakdug.g.

• Journal of Pharmaceutical Investigation
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• v.30 no.4
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• pp.253-258
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• 2000

In order to design the oral vaccine delivery system, we prepared the alginate micro spheres containing GFP (green fluorescent protein) as a model drug by spray method. To optimize the preparation conditions of microspheres, we investigated the effects of various parameters including nozzle pressure, nozzle opening angle, and concentrations of sodium alginate and calcium chloride. The prepared microspheres were evaluated by measuring their sizes, loading efficiency, and morphology. The particle size of microspheres was affected by the concentration of sodium alginate and calcium chloride, nozzle pressure, and nozzle opening angle. As the concentration of sodium alginate increased, GFP loading efficiency and particles size of microsphere also increased. However, it was observed to be difficult to spray the sodium alginate solution with concentration greater than 1.5% (w/v), due to high viscosity. The pressure over $3\;kgf/cm^2$ didn't affect the size of particles. As a result, the spraying method enabled us to prepare microspheres for oral vaccine delivery system. In this study, microspheres prepared with 1% (w/v) sodium alginate had greater loading efficiency and better spherical shape.

• Microbiology and Biotechnology Letters
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• v.20 no.4
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• pp.459-469
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• 1992

The immobilization characteristics of Zymomonas mobilis for ethanol production were examined. Four different strains of Zymomonas mobilis have been used for ethanol production. Among those, Zymomonas mobilis KCTC 1534 has been selected as the best strain for the highest ethanol productivity from glucose and sucrose. The optimum temperature and pH of the selected strain for ethanol production were $37^{\circ}C$ and 5.0 respectively for both free and immobilized cells. When the cells were immobilized by the gel entrapment method, the immobilized cells could produce ethanol at a little higher temperature than free cells. Calcium alginate was selected as the best gel for immobilizing cells. The immobilized cells could maintain the viability of 80% in 10 weeks storage at $4^{\circ}C$ in the medium with 2% calcium chloride. 20-25 hours of preincubation in 10% glucose solution was required for the activation of immobilized cells entrapped within calcium alginate gel.

• Environmental Engineering Research
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• v.11 no.5
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• pp.266-276
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• 2006

Commonly, the flocculant is dissolved in process or recycle water in industrial plant which has many ionic materials. Therefore, the polymer degradation in aqueous solution by chemical, mechanical or bacteriological may occur, sometimes rapidly. Even if the same flocculant is dissolved, the flocculation characteristics and the properties of dissolving polymer varied with the kind of dissolving water. In this study, we try to estimate the interaction between flocculants and ionic materials in dissolving water using self inversing emulsion polymer; polyacrylamide-co-trimethyl ammonium ethyl acrylate chloride flocculants which have varying molecular weights and structures at a several conditions. The polymeric flocculant is dissolved in artificial dissolving water with Potassium Chloride (PC), Calcium Chloride anhydrous (CC), Potassium Hydroxide (PH), Sodium Chloride (SC), Sodium Bromate (SB) and Iron (II) Sulfate Heptahydrate (IS) as ionic sources. Experimental results indicate that the cationic and anionic ions in dissolving water induce the hydrolysis, degradation of cationic functional group and uncoiling of polymeric flocculants, therefore, the flocculation efficiency decreased by undesired polymer. According that result, it is important to estimate not only its structures and physical properties but also the qualities of dissolving water to optimize the efficiency.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.1
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• pp.20-25
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• 2016

This study elucidated the effects of physicochemical factors on the production of cooked rice analogs using calcium alginate gels. Cooked rice analogs were prepared using various sodium alginate concentrations, agitation speeds, dropping distances, coating times, curing times and heating times. The diameter ratio and rupture strength of authentic cooked rice were 0.38 and 268.4 kPa, respectively. The diameter ratio of the analogs prepared with 0.7% (w/v) sodium alginate was 0.39, which was the closest to that of authentic cooked rice. When sodium alginate solution (0.7%, w/v) was dropped into calcium chloride solution (2%, w/v) via a nozzle, the diameter ratio of the analogs at an agitation speed of 520 rpm was 0.39. The optimal dropping distance was 8 cm and the optimal coating and curing times were each 20 min. The analogs were coated with β-cyclodextrin to improve their physical properties. The diameter ratio of the coated analogs was little changed; however, the rupture strength decreased slightly after heating for 60 min at 95°C.

• Clean Technology
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• v.29 no.2
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• pp.95-101
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• 2023

An experiment was conducted to produce vaterite-type precipitated calcium carbonate from waste oyster shells in order to use them as recyclable resources. Calcined oyster shells containing calcium oxide as their main component were prepared at a temperature of 800℃ for 24 h. The oyster shells were dissolved in nitric acid or hydrochloric acid solution to make 0.1 M calcium nitrate or calcium chloride aqueous solution, and a carbonation reaction was performed using a 0.1 M sodium carbonate aqueous solution under various experimental conditions, which included varying the amount of aspatic acid additive, the amount of NH₄OH added, the reaction time, the reaction temperature, the stirring speed, and the type of dissolved acid. The XRD, SEM, and size distributions were analyzed and the vaterite content was calculated. Spherical precipitated calcium carbonate with a vaterite content of 95.9% was synthesized by adding 0.1 mol aspatic acid/1 mol CaO and 2 cm³ of NH₄OH, and reacting for 1 h at 25℃ while stirring at 600 rpm. The average particle diameter was found to be 12.11 ㎛. Calcium carbonate contatining high vaterite is used as high value added calcium carbonate for medical, food, inke additiver, etc.

• Journal of Navigation and Port Research
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• v.46 no.4
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• pp.297-302
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• 2022

An exothermic oil absorbent sheet with calcium chloride crystals can be fabricated, by dipping a clean polypropylene fabric in calcium carbonate and hydrochloric acid solution and drying it. The exothermic oil absorbent sheet applied to the seawater surface, releases heat by the dissociation of calcium chloride. The dissociation heat liquefies the solidified low-sulfur fuel oil at a low temperature, and converts it to a state at which it can be absorbed. The optimum mole concentrations of calcium carbonate and hydrochloric acid required for the exothermic oil absorbent sheet, are 0.25 M and 0.5 M, respectively. The oil absorption capacity of the exothermic oil absorbent sheet for low sulfur fuel oil depends on the seawater temperature. But, it is highly excellent at 4.5-7.08 g/g at 10℃, the average seawater temperature during the winter in Korea. The exothermic oil absorbent sheet is an excellent alternative in absorbing low-sulfur fuel oil in winter and removing it from seawater.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.247.1-247.1
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• 2003

Iron deficiency is the most common nutritional problem worldwide. Oral iron supplementation programs have failed because of noncompliance and gastrointestinal toxicity. The purpose of this study was to explore the possibility of alginate gel bead as an oral controlled release system of iron supplements and increase the stability of iron succinyl casein (ISC). Alginate beads containing ISC were prepared by the gelation of sodium alginate with calcium cations. The release profiles of ISC were investigated according to the concentration of polymer, the drug/sodium alginate ratio, the concentration and type of cation, curing time and pH of calcium chloride solution. (omitted)