• Journal of the korean academy of Pediatric Dentistry
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• v.45 no.2
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• pp.179-184
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• 2018

Resin infiltration has been used as a treatment option for the management of early caries lesions recently. However, the etching procedure with hydrochloric acid might be somewhat stressful for the clinicians due to safety problem especially for young children, leading to less utility. This study aims at searching for some alternative surface pretreatment methods of resin infiltration for the early caries lesions in primary anterior teeth by comparing penetration depth of various methods. No significant difference was found in penetration ratio between etched surface with 15% hydrochloric acid and 35% phosphoric acid. However, the penetration ratio was significantly higher in groups pretreated either with dental pumice or abrasive metal strip (p < .05). By the result of this study, etching with phosphoric acid as an alternative of hydrochloric acid was thought clinically acceptable as a pretreatment method for resin infiltration in early caries lesions for primary anterior teeth. It was notable that surface conditioning with dental pumice or metal strip before etching was effective in increasing the penetration. This procedural modification might be much more correspondent with minimally invasive concept and hopefully contribute to increased safety and utility in pediatric dentistry.

• Bulletin of the Korean Chemical Society
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• v.17 no.10
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• pp.964-967
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• 1996

• Bulletin of the Korean Chemical Society
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• v.7 no.2
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• pp.158-159
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• 1986

• Bulletin of the Korean Chemical Society
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• v.35 no.4
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• pp.1029-1035
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• 2014

The protolytic dissociation process of hydrochloric acid (HCl) and hydrofluoric acid (HF) is studied using the B3LYP and MP2 methods with the 6-311+G(d,p) basis set in the gas phase and in aqueous solution. To study the phenomena in detail, discrete and discrete/continuum models were applied by placing water molecules in various positions around the acid. The dissociation process was studied using the thermodynamic cycle involving the structures optimized both in the gas phase and in aqueous solution and was analyzed with two key energy factors, relaxation free energy (${\Delta}G_{Rex(g)}$) and solvation free energy (${\Delta}G_s$). Based on the results, we could understand the dissociation mechanism and wish to propose the best way to study acid dissociation process using the CPCM methodology in aqueous solution.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.43 no.1
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• pp.65-73
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• 2011

The fibrous raw materials in packaging-grade paper production in Korea were mainly obtained from waste paper. The use of recycled paper has both positive and negative impacts in papermaking process. The primary positive impacts are the environmental protection and manufacturing cost reduction, and the negative impacts are the quality reduction in paper quality and the accumulation of heavy metals and other pollutants in wet- and dry-end process. This study was carried out to consider the optimum acid decomposition system with the highest recovery rate for the analysis of heavy metals in packaging-grade paper. The open digestion system using Kjeldahl apparatus and the closed digestion system using microwave oven for decomposing the organic materials in paper were compared. In both open and closed digestion method, the combination of nitric acid, hydrochloric acid and hydrogen peroxide showed higher recovery rate than using only nitric acid alone because the presence of Cl- ions in hydrochloric acid stabilizes ligand formation with metal ions. KOCC was observed to have the highest heavy metal content among the recycled paper samples. The heavy metal contents decomposed with the closed digestion system were relatively higher than with open digestion system.

• Current Research on Agriculture and Life Sciences
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• v.1
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• pp.55-65
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• 1983

The purpose of this study is to find out influences of several chemicals on the solubility of cocoon sericin in water, and there are several results of use to control the solubility of cocoon sericin in water. The results obtained are summarized as follows : The chemical which shows the strongest accelerating power of the solubility of cocoon sericin in water is Sodium Hydroxide (NaOH), the second is Potassium Hydroxide (KOH), the third is Sodium Silicate ($Na_2SiO_3$), and the weakest is Sodium Bicarbonate ($NaHCO_3$) in order among noticed silk-reeling accelerators. The chemical which shows the strongest inhibiting power of the solubility of cocoon sericin in water is Form Aldehyde (HCHO), the second is Ammonium Alum ($Al_2(SO_4)_2{\cdot}(NH_4)_2SO_4{\cdot}24H_2O$), the third is Acetic Acid ($CH_3COOH$), the weakest is Hydrochloric Acid(HCl) in order among noticed silk-reeling inhibitors. Particulary Hydrochloric Acid (HCl), which is expected to show strong inhibiting power of the solubility of cocoon sericin in water, shows accelerating power of the solubility of cocoon sericin at high temperature over 80 degrees of Celsius thermometer in water.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.6
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• pp.1110-1116
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• 1998

To determine the optimum conditions for the enzymic hydrolysis against wheat gluten of high con centrations (6~14%, w/w, protein), a hydrolysis system combining weak acid pretreatment and enzymic hydrolysis was investigated. Alcalase showed the highest DH(degree of hydrolysis) of the tested proteases. After hydrolysis by alcalase, subsequently peptidases were applied for the better DH of the wheat gluten hydrolyzate. Peptidase NP2 showed the highest DH of the tested peptidases, but flavour zyme was shown for the lowest bitter taste of the resulting hydrolyzate. In order to minimize aggregation or gelling at higher initial substrate concentration during heat treatment, wheat gluten suspension was pretreated with possibly low concentrations of hydrochloric acid at 105oC for 1 hour, and then enzy matically hydrolysed with alcalase and subsequently with flavourzyme. Each required minimum concen tration of hydrochloric acid in the wheat gluten suspension of 6, 8, 10, 12, and 14%(w/w, protein) was 0.10, 0.15, 0.20, 0.225, and 0.275N, respectively. After the subsequent enzymic treatment by alcalase and peptidase NP2 for 24 hrs, the nitrogen solubility in the final wheat gluten hydrolysates was increased to 94.9, 86.4, 85.3, 89.3 and 95.0%, and their amino nitrogen content was increased to 2.87, 5.68, 7.34, 9.71 and 12.50mg/m, respectively.

• Analytical Science and Technology
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• v.14 no.1
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• pp.34-43
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• 2001

The present work is aimed to evaluate the conditions of the hydride generation (HG) for germanium analysis by inductively coupled plasma (ICP)-atomic emission spectrometry (AES). Twelve different kinds of acids were used such as phosphoric, hydrochloric, nitric, sulfuric, perchloric, boric, tartaric, malic, oxalic, tannic, citric, and acetic acid. It was found that phosphoric acid yielded the maximum efficiency of hydride generation. Also, efficient hydride generation was obtined with the buffer solutions containing phosphate ions over a wide range of pH. In addition, in the presence of phosphoric acid the interference caused by metals was suppressed in the hydride generation of germanium. As the concentrations of a reducing agent and a stabilizing increased the hydride generation efficiency and the acid concentration proviaing the maximum intensity were increased. By using an analytical method developed in this study, the contents of germanium in water and rock samples were determined. The detection limit of germanium in the presence of phosphoric acid was $0.03{\mu}g/L$.

• Journal of the Korean Wood Science and Technology
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• v.41 no.1
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• pp.1-11
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• 2013

In this study, we investigated chemical characteristics of solid residues obtained from inorganic acid hydrolysis of hybrid poplar (Populus alba ${\times}$ glandulosa). Different concentration (72, 36, 18%) of sulfuric acid and hydrochloric acid were used for first hydrolysis step and second hydrolysis step were carried out after equally dilution to 4%. Solid residues after consecutive two step hydrolysis were named to RS72 (Residue from Sulfuric acid 72%), RS36, RS18, as well as RC36 (Residue from hydroChloric acid 36%) and RC18, respectively. The yield of RS decreased from 71.2% to 21.4% with increasing sulfuric acid concentration in the first hydrolysis step, whereas that of RC showed little difference (67.0% to 65.0%), irrespective of hydrochloric acid concentration. The lignin content in solid residue was 23.6% for both of RS36 and RS18, 25.6% for RC36 and 27.3% for RC18, respectively. The results of pyrolyzer-GC/MS showed that 24 cellulose derivatives (Levoglucosan, Furfural) and 21 lignin derivatives (Guaiacol, Syringol) were detected. Thermogravimetric analysis indicated that the yield of char increased and maximum wieght loss rate decreased with increasing lignin portion of solid residue. Therefore, structure of lignin was condensed effectively by sulfuric acid and by high concentration of acid.

• Bulletin of the Korean Chemical Society
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• v.20 no.12
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• pp.1433-1436
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• 1999

The 2-(2,4-dimethoxyphenyl)-4-MDO (2) underwent polymerization with ring opening as well as cyclization reaction in the presence of various cationic catalysts such as boron trifluoride, trifluoromethanesulfonic acid, p-toluenesulfonic acid, hydrochloric acid and trifluoroacetic acid. They afforded a mixture of the ring-opened poly(keto ether) and 3(2H)-dihydrofuranone derivative. Both the methylene group and oxygen atom of 1,3-dioxolane ring were participated in the reaction with cationic catalyst. The contents of the polymer and cyclization product were variable according to the acid strength of the cationic catalysts.