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Effect of Accelerated Aging on the Color Stability of Dual-Cured Self-Adhesive Resin Cements
Kim, Ah-Rang,Jeon, Yong-Chan,Jeong, Chang-Mo,Yun, Mi-Jung,Huh, Jung-Bo Korean Academy of Dental Science 2015 Journal of korean dental science Vol.8 No.2
Purpose: The effect of accelerated aging on color stability of various dual-cured self-adhesive resin cements were evaluated in this study. Materials and Methods: Color stability was examined using three different brands of dual-cured self-adhesive resin cements: G-CEM LinkAce (GC America), MaxCem Elite (Kerr), and PermaCem 2.0 (DMG) with the equivalent color shade. Each resin cement was filled with Teflon mold which has 6 mm diameter and 2 mm thickness. Each specimen was light cured for 20 seconds using light emitting diode (LED) light curing unit. In order to evaluate the effect of accelerated aging on color stability, color parameters (Commission Internationale de l'Eclairage, CIE $L^*$, $a^*$, $b^*$) and color differences (${\Delta}E^*$) were measured at three times: immediately, after 24 hours, and after thermocycling. The $L^*$, $a^*$, $b^*$ values were analyzed using Friedman test and ${\Delta}E^*$ values on the effect of 24 hours and accelerated aging were analyzed using t-test. These values were compared with the limit value of color difference (${\Delta}E^*=3.7$) for dental restoration. One-way ANOVA and Scheff's test (P<0.05) were performed to analyze each ${\Delta}E^*$ values between cements at each test period. Result: There was statistically significant difference in comparison of color specification ($L^*$, $a^*$, $b^*$) values after accelerated aging except $L^*$ value of G-CEM LinkAce (P<0.05). After 24 hours, color difference (${\Delta}E^*$) values were ranged from 2.47 to 3.48 and $L^*$ values decreased and $b^*$ values increased in all types of cement and MaxCem Elite had high color stability (P<0.05). After thermocycling, color change's tendency of cement was varied and color difference (${\Delta}E^*$) values were ranged from 0.82 to 2.87 and G-CEM LinkAce had high color stability (P<0.05). Conclusion: Color stability of dual-cured self-adhesive resin cements after accelerated aging was evaluated and statistically significant color changes occurred within clinically acceptable range.
Kim, So-Yoen,Lee, Ah-Rang,Jin, Guo Fan,Cho, Yang-Jin,Son, Ho-Jin,Han, Won-Sik,Kang, Sang Ook American Chemical Society 2015 Journal of organic chemistry Vol.80 No.9
<P>We studied electronic change in oligothiophenes by employing o-carborane into a molecular array in which one or both end(s) were substituted by electron-withdrawing dicyano-vinyl group(s). Depending on mono- or bis-substitution at the o-carborane, a series of linear A(1)-D-A(2) (1a-1c) or V-shaped A(1)-D-A(2)-D-A(1) (2a-2c) oligothiophene chain structures of variable length were prepared; A(1), D, and A(2), represent dicyano-vinyl, oligothiophenyl, and o-carboranyl groups, respectively. Among this series, 2a shows strong electron-acceptor capability of o-carborane comparable to that of the dicyano-vinyl substituent, which can be elaborated by a conformational effect driven by cage sigma-*-pi* interaction. As a result, electronic communications between o-carborane and dicyano-vinyl groups are successfully achieved in 2a.</P>
Kim, Ah-Rang,Jeon, Yong-Chan,Jeong, Chang-Mo,Yun, Mi-Jung,Choi, Jae Won,Kwon, Yong Hoon,Huh, Jung-Bo JAPANESE SOCIETY FOR DENTAL MATERIALS AND DEVICES 2016 Dental materials journal Vol.35 No.2
<P>The purpose of this study was to compare the compressive strength, diametral tensile strength and microhardnss of several self-adhesive resin cements (Rely-X U200, Clearfill SA Luting, G-CEM LinkAce, Maxcem Elite, PermaCem 2.0, and Zirconite) using different activation modes (self-cured, light -cured) and testing time (immediately, 24 h, thermocycling). Specimens were prepared for the compressive strength (empty set 4x6 mm) and diametral tensile strength and microhardness (empty set 6x3 mm) according to ISO standards. The strength after 24 h was higher than immediately after. In addition, G-CEM showed the highest values. In terms of the activation modes, Rely-X U200, PermaCem 2.0 had higher values in the light-curing than the self-curing. In conclusion, all cements demonstrated clinically available strength values and revealed differences in strength according to their composition, testing time and activation mode. Furthermore, correlation was found between the microhardness (degree of conversion) and mechanical strengths of the cements tested.</P>
Ah Rang Kang,Min Jee Kim,In Ah Park,Iksoo Kim 한국응용곤충학회 2014 한국응용곤충학회 학술대회논문집 Vol.2014 No.10
A partial sequence of the mitochondrial cytochrome oxidase subunit I (COI) gene is widely used as a molecular marker for species identification in animals, also termed a DNA barcode. However, the presence of more than one sequence type in a single individual, also known as heteroplasmy, is one of the shortcomings of barcode identification. In this study, we examined the extent and divergence of COI heteroplasmy, including nuclear-encoded mitochondrial pseudogenes (NUMTs), at the genomic-DNA level from 13 insect species, including four individuals of orthopteran Anapodisma miramae. Furthermore, a long fragment of mitochondrial DNA (~13.5 kb) and cDNA from A. miramae were used as a template for COI PCR to compare the patterns of heteroplasmy between DNA sources and to investigate a possible way to avoid ambiguity in DNA barcoding. When multiple numbers of clones originated from genomic DNA were sequenced, heteroplasmy was prevalent in all species (3~16 heteroplasmic copies), with a varying degree of maximum sequence divergence (<1% in 7 species, <4% in 3 species, <6% in 2 species and 2.15-8.03% in four A. miramae individuals). In five species, NUMTs also were observed when genomic DNA was used as a template. Long fragment DNA also is a source of heteroplasmic amplification, but the divergent haplotypes and NUMTs obtained in the genomic DNA-based PCR were not detected in A. miramae. On the other hand, cDNA was heteroplasmy-free, without NUMTs when multiple numbers of clones were sequenced. Consistently, one dominant haplotype was always obtained from the genomic DNA-origin clones in all species and also from the long fragment- and cDNA-origin clones of A. miramae. Furthermore, the dominant haplotype was identical in sequence, regardless of the DNA source. Thus, one possible solution to avoid the barcoding problem in relationship to heteroplasmy could be the acquisition of multiple numbers of barcoding sequences to determine a dominant haplotype that can be assigned as barcoding sequence for a given species.
Ah Rang Kang,Jee Yeon Baek,Sang Hyun Lee,Young Sik Cho,Wol Soo Kim,Yeon Soo Han,Iksoo Kim 한국응용곤충학회 2011 한국응용곤충학회 학술대회논문집 Vol.2011 No.05
The pear psylla, Cacopsylla pyricola Foerster (Homoptera: Psyllidae), is a serious insect pest of commercial pear crops. The species, which resides on pear trees throughout its life cycle, is rapidly spreading in some regions of the world. Given the life cycle, it is unclear how such a rapid spread has been facilitated. Presently, the population genetic structure of the species including genetic diversity and gene flow was studied to understand the nature of dispersal and field ecology of the species. Pear psylla was collected from several pear orchards in Korea. The 658-bp region of mitochondrial COI gene and the 716-bp long complete internal transcribed spacer 2 (ITS2) of the nuclear ribosomal DNA were sequenced. Unlikely other previously studied insect pests, the COI-based genetic diversity of the pear psylla was extremely low (maximum sequence divergence of 0.15%). This finding allowed us to conclude that the species may have been introduced in Korea relatively recently, possibly with the phenomenon of genetic bottlenecks. ITS2 sequence-based analyses of phylogeny, population differentiation, gene flow, and hierarchical population structure all concordantly suggested that the pear psylla populations in Korea are neither genetically isolated nor hampered for gene flow. These genetic data are concordant with the dispersal of an overwintering winterform morph outside the non-pear habitat in the fall and the possibility of subsequently longer distant dispersal.
Anti-inflammatory and anti-nociceptive effects of extract of Astragalus membranaceous
Kim, Young-Ock,Kim, Su-Kang,Cho, Ah-Rang,Chung, Joo-Ho Kyung Hee Oriental Medicine Research Center 2008 Oriental pharmacy and experimental medicine Vol.7 No.5
The root of Astragalus membranaceous (AM) has been used to treat edema and arthritis in the traditional Korean medicine. To elucidate the anti-inflammatory and anti-nociceptive effects of ethanol extract of AM, the carrageenan-induced paw edema using a plethysmometer and thermal hypersensitivity using the plantar test were measured. Ibuprofen was used as a control drug. Pretreatment with AM (400 mg/kg p.o.) significantly reduced paw edema, compared to the carrageenan-treated rats. In the plantar test, the thermal withdrawal latency in AM-treated group was significantly increased than the carrageenan-treated group. The results indicate that AM could have be the anti-inflammatory and anti-nociceptive properties.