• Restorative Dentistry and Endodontics
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• v.24 no.1
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• pp.88-99
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• 1999

The purpose of this study was to investigate the physical properties of experimental composite resins made with the spherical and crushed fillers. The 14 experimental composite resins containing 0, 5, 10, 15, 20 and 25%(w/w) in spherical filler group and 0, 10, 20, 30, 40, 50, 60 and 70%(w/w) in crushed filler group, incorporated in a Bis-GMA matrix (Aldrich Co., USA), were made with 1% ${\gamma}$-methoxy silane treated fillers. The polymer matrix was made by dissolving 0.7%(w/w) of benzoyl peroxide(Janssen Chemical Co. Japan) in methacrylate monomer, whereupon 0.7%(v/v) N,N-dimethyl-p-toluidine(Tokyo Kasei Co. Japan) was added to the monomer. The weight percentage of each specific particle size distribution could be determined from a knowledge of the specific gravity, the weight(w/w), and corresponding volume %(v/v) of the filler sample in resin monomer. In crushed silica group and spherical silica group, the diametral tensile strengths and compressive strengths were measured with Instron Testing Machine(No.4467), and analyzed in 14 experimental composite resins made by filler fractions. The shear bond strength of 14 experimental composite resins to bovine enamel was measured with universal testing machine(Instron No.4467). The fracture surfaces were sputter-coated with a gold film and investigated by SEM. The results were as follows; 1. The diametral tensile strength was tendency to increase in crushed silica group, but not in spherical silica group. The highest diametral tensile strength was found in 20% filler fractions of two groups. 2. The compressive strength was higher in 15%(w/w) and 20%(w/w) in spherical silica group than in crushed silica group, but not in spherical silica group. 3. The significant correlation was noticed in increase in shear bond strength in crushed silica group, but not in spherical silica group. 4. The significantly highest shear bond strength was noticed in 50% filler concentration in crushed silica group, and in 15% filler concentration in spherical silica group, it was not significant in relation. 5. In crushed silica group, cut surface of resin matrix and the interface between resin and filler is obvious. In spherical silica group, fractures that occurred through the filler particles were round in shape.

• Journal of the Korean Chemical Society
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• v.41 no.2
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• pp.98-104
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• 1997

A simple, accurate and reproducible capillary electrophoresis(CE) assay has been developed for the determination of berberine, cinnamic acid, and glycyrrhizin which are used in traditional Korean medicinal preparations. Separation of these compounds was performed in 20 mM phosphate buffer(pH 7.5) and acetonitrile(75:25, v/v) using a bare fused silica capillary($57 cm{\times}75 {\mu}m$ i.d.) at 25$^{\circ}C$. With the electric field of 350 V/cm, the time needed for the separation of berberine, cinnamic acid and glycyrrhizin was within 13 min. Calibration curves were linear for 1∼100 ${\mu}g/mL$ berberine, 0.3∼100 ${\mu}g/mL$ cinnamic acid and 2.5∼100 ${\mu}g/mL$ glycyrrhizin. The ranges of relative standard deviations(n=5) for those samples were between 0.96∼2.35%. The limits of detection(S/N=3) for berberine, cinnamic acid and glycyrrhizin were 0.5, 0.1 and 2.0 ${\mu}g/mL$, respectively. The numbers of theoretical plates were 181,000(berberine), 88,000(cinnamic acid) and 169,000(glycyrrhizin), while they were 3,100∼4,800 in HPLC.