• Restorative Dentistry and Endodontics
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• v.25 no.2
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• pp.272-288
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• 2000

Calcium hydroxide is used as a root canal medicament with its several pharmacological effects. However, it has been known that the usage of calcium hydroxide in the root canal system before canal filling with gutta-percha and zinc oxide eugenol-based cement induced change in the properties of root canal cement which might adversely affect sealing ability of the canal filling. The purpose of this study was to identify the reactivity of calcium hydroxide-eugenol compound made from chemical interaction of between calcium hydroxide and zinc oxide eugenol. Chemical properties of calcium hydroxide, eugenol, zinc oxide eugenol, calcium hydroxide-eugenol and calcium hydroxide-zinc oxide eugenol compound were analyzed using XRD. FT-IR Spectrophotometer and FT-NMR Spectrometer. The results were as follows: 1. The compound made from interaction between calcium hydroxide and zinc oxide eugenol was as follows : 2. Calcium hydroxide was shown to make chemical bond (ionic bond) with eugenol. 3. Since bonding between $Ca^{2+}$ and eugenol is simple ionic nature, under water existence, calcium hydroxide-eugenol compound may be ionized easily and its physical property be deteriorated.

• The Journal of Korean Academy of Prosthodontics
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• v.15 no.1
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• pp.43-47
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• 1977

The purpose of this study was to determine human pulp reactions to temporary cements such as zinc oxide-eugenol cement, modified zinc oxide-eugenol cement (Cavitec) and calcium hydroxide cement (Dycal). Deep class V cavities were prepared in the human teeth with ultrahigh-speed handpiece operating at a free running speed of 300,000 r.p.m., using # 701 bur and water spray coolant. The cavities were flushed with water, dried with cotton pellets and filled with zinc oxide-eugenol cement, modified zinc oxide-eugenol cement and calcium hydroxide cement respectively. The teeth were divided into two groups, which one group was extracted after One day and the other was extracted after seven days. The samples were examined with microscope and the findings were as follows; 1. The pulp reactions to temporary cements were generally mild. Among them the reactions were moderate in zinc oxide-eugenol cement and, slight in calcium hydroxide cement. 2. Calcium hydroxide cement may be used properly as temporary cement for the purpose of pulp protection.

• Restorative Dentistry and Endodontics
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• v.6 no.1
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• pp.27-35
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• 1980

This study was to evaluate the effectiveness of a few disinfectant on amputated pulps of domestic dogs. The materials employed for the purpose were zinc oxide eugenol paste, calcium hydroxide as control groups and guaiacol (1%, 5%, 10% by weight) added zinc oxide eugenol paste and formaldehyde (1%, 5%, 10% by weight) added calcium hydroxide as experimental groups. Following were the results obtained throngh histo-pathological examination. 1) In calcium hydroxide-formaldehyde groups, secondary dentin formation was observed in the 2 weeks, but the remaining pulp tissue was severely atrophied according to the concentration of formaldehyde and the time increased. 2) In zinc oxide eugenol-guaiacol groups, the first evidence of secondary dentin formation was observed in the 3 weeks. It seems that the concentration variety of guaiacol influenced very little to the potential ability of dentin formation. 3) Except 1% formaldehyde containing calcium hydroxide group, every group showed severe pulp degeneration. In all groups of zinc oxide eugenol-guaiacol cases revealed the tendency of recovery.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.448-452
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• 2001

An Experimental study was carried out to develop a simple method of processing copper waste sludge which is produced by PBC manufacturing. The procedure is based on leaching of wet sludge in 2N H$_2$SO$_4$, and the solid / liquid ratio is controlled approximately at 1/10. The recovery of copper is 85.4%, and pH of the leachate is 3.20. Adding ammonia solution into leachate forms ammine, and hydroxide compounds derived from other impurities in leachate at pH 10. The hydroxide compound can be treated by ferrite process, and the product is a stable oxide compound. Then the ammine solution is heated to evaporate ammonia, and the copper hydroxide is formed. Heating at 8$0^{\circ}C$by aeration, copper hydroxide is transformed into copper oxide with a purity of 98.4%. This process can recover most copper from sludge and the residue can be stabilized by the formation of a stable oxide compound which is not hazardous to environment.

• Journal of Korean Society on Water Environment
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• v.27 no.4
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• pp.486-490
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• 2011

As(V) adsorption on aluminum oxide powder which was recycled from industrial wastes containing aluminum hydroxide was evaluated. Aluminum oxide powder in this study was prepared by calcinating aluminum hydroxide wastes at$550^{\circ}C$. Spectroscopic analysis indicated that the aluminum hydroxide wastes were changed to aluminum oxide by calcination. Arsenic adsorption isotherm was conducted with variation of ionic strength and multiple-ion systems using Ca(II) and Cu(II). As(V) removal showed typical anionic adsorption characteristics that the removal efficiency decreased with increasing pH in single As(V) system as well as in binary and ternary system. More than 80% of As(V) at an initial concentration of $5{\times}10^{-5}$ M was removed from aluminum oxide powder in As(V) single system. The effect of ionic strength on As(V) adsorption was negligible, which indicated the strong bonding between aluminum oxide powder and As(V). The removal efficiency of As(V) was higher in a binary system with Cu(II) than in a binary system with Ca(II).

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.19 no.3
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• pp.353-366
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• 2021

The solubilities of different multicomponent lanthanide oxide (Ln₂O₃) solid solutions including binary (Ln₁ and Ln₂ = La, Nd, Eu, or Tm), ternary (Ln₁, Ln₂, and Ln₃ = La, Nd, Eu, or Tm), and higher systems (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) were studied after aging for four weeks at 60℃. Our recent study revealed that the phase transformations in binary ((La, Nd) and (La, Eu)) and ternary (La, Nd, Eu) systems are responsible for the formation of (La, Nd)(OH)₃, (La, Eu)(OH)₃, and (La, Nd, Eu)(OH)₃ solid solutions, respectively. The variations in the mole fractions of La³⁺, Nd³⁺, and Eu³⁺ in the sample solutions of these hydroxide solid solutions indicated that a thermodynamic equilibrium might account for the apparent La, Nd, and Eu solubilities. Conversely, the binary and ternary systems containing Tm₂O₃ as the heavy lanthanide oxide retained the oxide-based solid solutions, and their solubility behaviors were dominated by their congruent dissolutions. In the higher multicomponent system, the X-ray diffraction patterns of the solid phases, before and after contact with the aqueous phase indicated the formation of a stable oxide solid solution and their solubility behavior was explained by its congruent dissolution.

• Journal of Electrochemical Science and Technology
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• v.8 no.2
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• pp.146-154
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• 2017

In this study, copper (II) oxide was prepared for use in a copper electroplating solution. Copper chloride powder and copper (II) oxide are widely used as raw materials for electroplating. Copper (II) oxide was synthesized in this study using a two-step chemical reaction. Herein, we developed a method for the preparation of copper (II) oxide without the use of sintering. In the first step, copper carbonate was prepared without sintering, and then copper (II) oxide was synthesized without sintering using sodium hydroxide. The optimum amount of sodium hydroxide used for this process was 120 g and the optimum reaction temperature was $120^{\circ}C$ regardless of the starting material.

• Restorative Dentistry and Endodontics
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• v.6 no.1
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• pp.17-25
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• 1980

The purpose of this study was to evaluate the pulpal response against calcium hydroxide and zinc oxide containing various concentration of formocresol (0.1, 0.5, 1, 5, 10, 20 and 30%). The experiment was performed on dog's teeth (75 teeth from 5 dogs: Table 1.) and the teeth were routinly treated in laboratory procedures. Followings are the results obtained through microscopical examination. 1. In zinc oxide group, intlammatory reaction was severe in low concentrated formocresol and the (higher the concentration of formocresol the milder the inflammatory reaction was more evident. 2. In zinc oxide group, inflammatory change was milder at 3 weeks than 1 week, and proliferation of young connective tissue was seen at 3 weeks. 3. In calcium hydroxide group, inflammatory change in relation to the concentration of formocresol was not noticeable. 4. In calcium hydroxide group, repair process with decreased inflammatory reaction and fibrosis, and dentin bridge like layer was found at 3 weeks.

• Journal of Korean society of Dental Hygiene
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• v.18 no.4
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• pp.423-432
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• 2018

Objectives: Calcium hydroxide, a root canal temporary sealer, has long been used and it has anti-bacterial and anti-inflammatory activity. To investigate the properties of a newly developed calcium hydroxide paste comprising silicon-substituted hydroxyapatite (Si-HA), we examined the anti-inflammatory activity of the new calcium hydroxide paste in RAW 264.7 macrophages stimulated by lipopolysaccharide (LPS), which causes infection of the root canal. Methods: The test materials, including Calcipex II as control group and the newly developed TRC paste, were extracted from cell culture media and then diluted for experiment. In LPS-stimulated RAW 264.7 cells, the cytotoxicity and nitric oxide (NO) production of test materials were measured by MTT assay and Griess reagents, respectively. Also, the expression of the inducible nitric oxide synthase (iNOS) was assessed by western blotting. Results: The IC50 values of Calcipex II and TRC paste were $17.6mg/m{\ell}$ and $13.5mg/m{\ell}$, respectively. The level of NO, increased by LPS, was dose-dependently inhibited more by TRC paste than Calcipex II treatment. In addition, iNOS expression was decreased by 71% and 92% at concentrations of $2mg/m{\ell}$ and $20mg/m{\ell}$ of TRC paste, respectively. Conclusions: We demonstrated that the Si-HA calcium hydroxide paste has a slightly improved anti-inflammatory property and further studies are needed before clinical recommendations are proposed.

• Resources Recycling
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• v.14 no.6 s.68
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• pp.3-9
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• 2005

In this study, the separation and recovery of cerium hydroxide was investigated from the wasted cerium polishing powders. Waste cerium polishing powder contains $64.5\;wt\%$ of rare earth oxide and the content of cerium oxide is $36.5\;wt\%$. Since cerium oxide, $56.3\%$ of rare earths, is the most stable state in rare earth, the dissolution of cerium oxide in acid solution is not easy. Therefore the process of rare earth oxide by sulfation and water leaching was examined in order to increase the recovery of rare earth. Rare earth elements were recovered in the form of $\Re{\cdot}Na(SO_{4})_{2}$ by the addition of sodium sulfate to leached solution. The slurry of rare earth hydroxide was prepared by the addition of $\Re{\cdot}Na(SO_{4})_{2}$ to sodium hydroxide solution. After the oxidation of cerous hydroxide($CE(OH)_{3}$) to ceric hydroxide($CE(OH)_{3}$) by aeration, ceric hydroxide was separated from other rare earth hydroxides by controlling the acidity of solution.