• The Journal of Advanced Prosthodontics
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• v.9 no.6
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• pp.416-422
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• 2017

PURPOSE. To investigate the effect of reducing tooth preparation and ceramic thickness on fracture resistance of lithium disilicate crowns. MATERIALS AND METHODS. Specimen preparation included a standard complete crown preparation of a typodont mandibular left first molar with an occlusal reduction of 2 mm, proximal/axial wall reduction of 1.5 mm, and 1.0 mm deep chamfer (Group A). Another typodont mandibular first molar was prepared with less tooth reduction: 1 mm occlusal and proximal/axial wall reduction and 0.8 mm chamfer (Group B). Twenty crowns were milled from each preparation corresponding to control group (n=5) and conditioned group of simultaneous thermal and mechanical loading in aqueous environment (n=15). All crowns were then loaded until fracture to determine the fracture load. RESULTS. The mean (SD) fracture load values (in Newton) for Group A were 2340 (83) and 2149 (649), and for Group B, 1752 (134) and 1054 (249) without and with fatigue, respectively. Reducing tooth preparation thickness significantly decreased fracture load of the crowns at baseline and after fatigue application. After fatigue, the mean fracture load statistically significantly decreased (P<.001) in Group B; however, it was not affected (P>.05) in Group A. CONCLUSION. Reducing the amount of tooth preparation by 0.5 mm on the occlusal and proximal/axial wall with a 0.8 mm chamfer significantly reduced fracture load of the restoration. Tooth reduction required for lithium disilicate crowns is a crucial factor for a long-term successful application of this all-ceramic system.

• Journal of the Korean Chemical Society
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• v.22 no.5
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• pp.320-325
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• 1978

In order to elucidate the mechanism associated with the solvent extraction of uranium(VI) using DEPA and DPPA as extractant the uranium(VI) complexes formed during the solvent extraction were isolated and characterized by means of IR, NMR, chemical analysis and molecular weight determination. It has been found that uranium(VI) replaces the acidic hydrogen ions of the extractants DEPA and DPPA to form chelated polynuclear complexes, the molecular weight of U(VI)-DEPA complex being $2.1{\times}10^4$. The isolated U(VI)-DEPA complex has been found to be the same chemical species as is formed during the solvent extraction process. In case of DEPA the distribution coefficient of uranium is the largest of the pure aqueous uranium solution and is increasing for the acidic solutions in the order of $H_3PO_4.

• Journal of the Korean Chemical Society
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• v.32 no.5
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• pp.458-463
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• 1988

The solubility parameter theory for retention behaviors of phenols in a reversed phase liquid chromatography can be applied to limited ranges of the aqueous solvent system. The many examples of the exception to this theory were found to show no agreement with the retention behavior of phenols. Therefore, a new solute-solvent interaction parameter, ${\delta}_{im}$ is added to the Schoenmakers equation of the solubility parameter theory in LC to approach the equation to the real one. The new solute-solvent interaction pararneter, ${\delta}_{im}$ depends on the kinds of solvent, the solvent composition and the structure of solutes. The parameter, ${\delta}_{im}$ has the linear relationship with the solubility parameter of mobile phase, ${\delta}_{im}$. The prediction of retention behavior by this modified equation turns out to be greater than the previous one.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2000.11a
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• pp.89-92
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• 2000

Non-aqueous tape casting of LTCC with PVB binder has been studied in a continuous tape casting machine. The aim of the study was to evaluate this type of system in the different Binder/Plasticizer and solid content compositions. Each four slurry compositions were used in the experiments with varied binder/plasticizer and solid content. All the slurries gave good quality tapes with smooth surfaces without blisters or pinholes. The highest mechanical properties was obtained for the B/P=3.0, powder content 70vol% composition from 52 ${\mu}{\textrm}{m}$ green tapes, a tensile strength of 4.6 MPa and a linear extension of 29.5%

• Preventive Nutrition and Food Science
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• v.20 no.2
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• pp.119-125
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• 2015

The biologically active compounds raphasatin and sulforaphene are formed during the hydrolysis of radishes by an endogenous myrosinase. Raphasatin is very unstable, and it is generated and simultaneously degraded to less active compounds during hydrolysis in aqueous media. This study determined the hydrolysis conditions to maximize the formation of raphasatin and sulforaphene by an endogenous myrosinase and minimize their degradation during the hydrolysis of radish roots. The reaction parameters, such as the reaction medium, reaction time, type of mixing, and reaction temperature were optimized. A stability test for raphasatin and sulforaphene was also performed during storage of the hydrolyzed products at $25^{\circ}C$ for 10 days. The formation and breakdown of raphasatin and sulforaphene in radish roots by endogenous enzymolysis was strongly influenced by the reaction medium, reaction time, and type of mixing. The production and stabilization of raphasatin in radishes was efficient in water and dichloromethane with shaking for 15 min at $25^{\circ}C$. For sulforaphene, the favorable condition was water as the reaction medium without shaking for 10 min at $25^{\circ}C$. The maximum yields of raphasatin and sulforaphene were achieved in a concurrent hydrolysis reaction without shaking in water for 10 min and then with shaking in dichloromethane for 15 min at $25^{\circ}C$. Under these conditions, the yields of raphasatin and sulforaphene were maximized at 12.89 and $1.93{\mu}mol/g$ of dry radish, respectively. The stabilities of raphasatin and sulforaphene in the hydrolyzed products were 56.4% and 86.5% after 10 days of storage in water and dichloromethane at $25^{\circ}C$.

• Journal of the Korean Chemical Society
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• v.33 no.4
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• pp.399-405
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• 1989

The dependence of voltammetric parameters on the pressure for the reduction of Cu(II) in 0.5M KCl aqueous solution has been studied. In this system micro platinum electrode, standard calomel electrode and a helix type of platinum wire were used as the working, the reference and the auxilary electrode, respectively. With increasing the pressure from 1 to 1,800 bars, the half wave potentials of first reduction wave are shifted to the more negative potentials. And the diffusion currents of first and second reduction wave become considerably larger with increase in pressure from 1 to about 1,000 bars but are getting smaller beyond 1,000 bars. The good linear relationships between diffusion current and the concentrations of Cu(II) are established over all pressure range($1{\sim}1,800$ bars). The reversibility of the each reduction step is not changed with increasing pressure.

• The Korea Journal of Herbology
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• v.35 no.6
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• pp.55-68
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• 2020

Objectives : We observed the possibilities that blue honeysuckle has favorable analgesic or refinement effects on the Primary dysmenorrhea (PD) in rats. Methods : Estradiol benzoate and oxytocin were used to induce the PD rat model. And Blue honeysuckle concentration lyophilized powders (BH) 500, 250 and 125 mg/kg and 500 mg/kg of Lonicerae Flos aqueous extract lyophilized powders (LF) were orally administered, once a day for 10 days at 30 min after each estradiol benzoate treatment. Then the changes on the body weights and gains during experimental periods, abdominal writhing response for analgesic activities, uterine weights, uterus lipid peroxidation, antioxidant defense system - glutathione contents, superoxide dismutase and catalase activities, NF-κB and COX-2 mRNA expressions were monitored with uterus histopathology including immunohistochemistry for tumor necrosis factor (TNF)-α and inducible nitric oxide synthase (iNOS).. Results : Inflammatory and oxidative stress mediated PD signs were favorably and dose-dependently inhibited by 10 days continuous oral administration of three different dosages of BH - 500, 250 and 125 mg/kg as comparable to those of indomethacin(IND) 5 mg/kg treated rats in BH 500 mg/kg administered PD rats, and similar to those of LF 500 mg/kg in BH 125 mg/kg, at least in a condition of the present PD rat model. Conclusions : The results suggest that BH has favorable analgesic and refinement activities on the estradiol benzoate and oxytocin treatment-induced PD signs through anti-inflammatory and antioxidative potentials.

• Polymer(Korea)
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• v.28 no.2
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• pp.154-161
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• 2004

Modified poly(4-vinylpyridine) was obtained by partial quarternization of nitrogen atoms in pyridine rings of poly(4-vinylpyridine) with methyl group. By means of laser light scattering and fluorescence, it was found that this modified polymer chains were aggregated in the aqueous solution and its structure was core-shell type. The hydrophobic parts of the chains were densely condensed in core part and the hydrophilic part of quarternized amino with positive charge formed the shell part. In the mixed system of modified poly(4-vinylpyridine) and anionic surfactant, sodium dodecyl sulfate, it was observed that a critical aggregation concentration existed and that this critical concentration was suddenly decreased above 0.1 M NaCl. The size change of aggregates was also investigated by dynamic light scattering while sodium dodecyl sulfate was added into polymer solution upto the critical aggregation concentration.

• Membrane Journal
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• v.8 no.1
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• pp.29-41
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• 1998

Thin-film composite reverse osmosis membranes of aromatic polyamides were prepared by the interfacial polymerization. Aromatic polyamides as active skin layer were made from the interfacial polymerization of MPD(m-phenylene diamine) in the aqueous and TMC(trimesoyl chloride) in HCFC(1,1-dichloro-1-fluoroethane) organic solvent. The performances of the various reverse osmosis composite membranes prepared by changing processing variables were examined. The performance of membrane manufactured by batch system was varied with organic solvent, monomer concentration, dipping time, heat treatment temperature, acid acceptor, ethanol post treatment, and acid post treatment. Ethanol post treatment was the most dominant factors in increasing permeate amount, while the monomer concentration and dipping time were the main factors in increasing selectivity. The spiral-wound module was produced with the membrane prepared at optimum condition of the continuous process. Comparing the performance of this membrane module made here with that of commercial membrane module, the permeate flux was increased by 33% while the rejection was decreased by 5%.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.1
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• pp.45-51
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• 1986

Equimolar aqueous solutions of D-glucose and glycine were heated at $50^{\circ}C\;and\;95^{\circ}C$ at pH 6.7. The headspace volatiles and the ether extracts from the reaction mixture were analyzed by gas chromatography and gas chromatography-mass spectrometry using a fused silica capillary column. The major components formed were identified as diacetyl, three furfurals, two pyrroles, one furanone, two pyranones and two amides. In order to elucidate the formation mechanisms of the amides formed front amino-carbonyl reaction, two model systems were adopted. N-butylacetamide were formed as major components from diacetyl-butylamine ana glyoxal-butylamine systems, respectively. The results obtained suggest that such ${\alpha}-dicarbonyls$ as 3-deoxy-D-erythro-2,3-hexodiulose and diacetyl generated in the amino-carbonyl reaction react with amino compounds, amides then being formed by cleavage of the C-C bond in the ${\alpha}-dicarbonyls$.