• Restorative Dentistry and Endodontics
• /
• 제24권3호
• /
• pp.473-481
• /
• 1999

This study evaluated the shear bond properties of IPS Empress glass ceramic to enamel and dentin surfaces with three ceramic surface treatments, and three resin cements. The influence of thermocycling was also investigated. The purpose of this study was to investigate the influences of resin cements, ceramic surface treatments, and thermocycling on shear bond properties. Ninety freshly extracted, noncarious human molars were selected for this study. The surface treatments of ceramic were etching <5.0% hydrofluoric acid, application of silane coupling agents(Tokuso Ceramic Primer, Clearfil porcelain bond, Monobond-S), and the combination of the two methods. Empress cylinders were bonded to enamel and dentin surfaces with three kinds of resin cements(Bistite resin cement, Panavia 21, Variolink). The specimens were aged in $37^{\circ}C$ distilled water for 24 hours. Half of the specimens were then thermocycled 500times between $5^{\circ}C$ and $55^{\circ}C$ with a dwell time of 15 seconds. Each specimen was debonded in shear mode and measured shear bond properties by using the universal testing machine(Zwick 020, Germany). The data were analyzed by SPSS/PC+(one-way ANOVA, Scheffe' s test and t-test). The results were as follows : 1. Without thermocyling, there was significant difference of shear bond strength to enamel surface between Bistite Resin Cement and Panavia 21 in case of etched and silane-treatment(p<0.05). 2. Without thermocyling, the shear bond strength of a group treated with silane and etching was significantly higher than that of a group treated with silane or etching with the application of Panavia 21 and Variolink(p<0.05). 3. A group treated with etching with the application of Variolink only showed a decrease of shear bond strength after thermocycling(p<0.05).

• 한국동물위생학회지
• /
• 제31권1호
• /
• pp.1-16
• /
• 2008

Salmonella infections cause the disease in pigs but also some zoonotic Salmonella serotypes can be transmitted to human through swine products, resulting in food poisoning. The objective of this study was to investigate the bacteriological prevalence and detection of invA gene using Salmonella specific polymerase chain reaction (PCR), the epidemiological characteristics related to Salmonella strains cultured from pig samples in Gangwon areas using serotyping, random amplified polymorphic DNA (RAPD) and pulsed field gel electrophoresis (PFGE) methods. During the period of November 2001 through April 2002, 1,174 ileocecal lymph node were collected from the slaughtered pigs raised in 38 farms located in Gangwon province. The samples were submerged in boiling water and macerated in saline and lymph node homogenates were inoculated into Tetrathionate broth with iodine (TTB, Difco, 0.5% iodine was added) for enrichment growth. Then additional tests were performed using several mediums, and suspects were identified by API 20E kit (BioMerieux) and PCR. Of total 1,174 samples from 38 farms, 44 (3.7%) were isolated as Salmonella spp from 13 farms (34.2%). Of 44 isolates, 31 were in Yangyang region, followed by 9 in Goseong, 2 in both Gangneung and Sokcho. However, there was no difference in regional isolation frequency. All isolates have a 521bp amplified product in Salmonella specific PCR with primer invA which encodes in proteins for invasion of epithelial cells. Of 44 recovered serotypes, 23 (52.3%) were S Eingedi, 10 (22.7%) S Schwarzengrund, 9 (20.5%) S Typhimurium, and 2 (4.5%) S Mbandaka. In RAPD analysis, there appeared to be unique bands distinguishing each serotype, although similarities exist between the different serotypes. Four serotypes of 44 Salmonella isolates appeared to fall into 14 different RAPD types. In PFGE analysis, 9 S Typhimurium were tested with XbaI enzyme and SpeI enzyme. The combination of results obtained with two enzymes subdivided the 9 S Typhimurium into 4 PFGE types.

• 대한치과보철학회지
• /
• 제38권4호
• /
• pp.427-437
• /
• 2000

Recently the 2nd generation laboratory composite resins were introduced. Although the mechanical properties of these composite resins have been improved, there were some disadvantages such as discoloration, low abrasion resistance and debonding between metal and resin. The purpose of this study was to evaluate the tensile bond strength between non-pecious dental alloy(verabond) and four veneering reinforced composite resins ; Targis(Ivoclar Co., U.S.A.), Artglass(Kulzer CO., Germany), Sculpture(Jeneric Pentron Co., U.S.A.), and Estonia(Kurary Co., Japan). All test metal specimens were polished with #1,000 SiC paper, and sandblasted with $250{\mu}m$ aluminum oxide. After then. according to manufacturer's instructions metal adhesive primer and veneering resins were applied. All test specimens were divided into two groups. One group was dried in a desiccator at $25^{\circ}C$ for 3 days, the other group was subjected to thermal cycling($2,000{\times}$) in water($5/55^{\circ}C$). Tensile bond strength was measured using Instron Universal Testing machine and the fractured surface was examined under the naked eyes and scanning electron microscope. Within the limitations imposed in this study, the following conclusions can be drawn: 1. In no-thermal cycling groups, there were no significant differences between Estenia and VMK68 but there were significant differences between Targis, Artglass, Sculpture and VMK68(p<0.05). 2. In no-thermal cycling resin groups, the highest tensile bond strength was observed in Estenia and there were significant differences between Estenia and the other resins(p<0.05). 3. Before and after thermal cycling, there were significant differences in tensile bond strength of Targis and Artglass(p<0.05). The tensile bond strength of Artglass was decreased and that of Targis was increased. 4. In no-thermal cycling groups, Artglass showed mixed fracture modes(95%), but after thermal cycling, Artglass showed adhesive fracture modes(75%).

• 한국환경생태학회지
• /
• 제25권4호
• /
• pp.470-478
• /
• 2011

본 연구는 멸종위기식물인 단양쑥부쟁이(Aster altaicus var. uchiyamae)의 개체군을 대상으로 유전다양성을 유지하는데 필요한 최소개체수를 산정하기 위하여 수행되었다. 단양쑥부쟁이가 분포하고 있는 네 지역에서 각각 유전다양성 및 유전적 분화도를 분석하였다. AFLP(amplified fragment length polymorphism) 마커를 이용한 유전적 변이의 분석결과, 총 4개의 프라이머 조합에 대해서 936개의 밴드가 확인되었으며, 그 중 934개의 밴드(99.8%)가 다형성을 보여주었다. 단양쑥부쟁이 개체군 내에서 유전다양성(PPB = 45.3%, h = 0.104, I = 0.168, hs = 0.108)은 높은 수준으로 나타났으며, 개체군 간 유전적 분화도($G_{ST}$ = 0.075, ${\theta}^B$ = 0.079)는 낮은 수준이었다. AMOVA(Analysis of molecular variance)분석 결과에서도 전체 유전적 변이 중 91%가 개체군 내에서 보이는 반면, 9%는 개체군 간 변이에 기인한 것으로 나타났다. 단양쑥부쟁이 개체군에서 보이는 유전적 특성은 개체군 간의 빈번한 유전자 이동에 기인한 것으로 사료된다. 최대화 전략법에 의하여 경기도 여주일대의 3개 개체군을 대상으로(굴암, 도리섬, 삼합) 개체군 내 최소개체수를 산정한 결과 도리섬개체군에서는 17개체, 삼합개체군에서는 16개체, 굴암개체군에서는 11개체로 파악되었다. 단양쑥부쟁이 개체군의 최소개체수에 대한 정보는 효율적인 현지 외 보전을 위한 가이드라인을 제시해 줄 수 있다.

• 한국식품영양과학회지
• /
• 제39권10호
• /
• pp.1522-1527
• /
• 2010

식품에 극소량 존재하는 Salmonella spp.를 real-time PCR로 검출 시 필요한 최소시간을 구하고자 하였다. Sal-F, Sal-R 서열이 primer로 사용되었으며 sal-P 서열이 probe로 사용되었다. BPW에서 산출된 검출한계는 $3.77{\times}10^2\;cfu/mL$로 측정되었다. BPW에 인위적으로 Salmonella spp.를 접종하였으며 성장곡선을 구하였다. 성장곡선은 y＝$0.0127x^2$+0.5927x-0.4317($R^2$=0.99) 식을 나타내었다. 25 g 시료에 1 cell의 Salmonella spp.가 존재한다고 가정할 경우, 시료처리 과정에서 10배로 희석되므로 초기 균 농도는 0.004 cfu/mL 이며 이 농도에서 검출한계까지의 균수 증가가 발생해야 real-time PCR로 검출이 가능할 것으로 판단되었다. 성장곡선에서 균수 증가에 필요한 시간을 측정해 본 결과 7시간20분으로 산출되었으며 따라서 PCR 수행시간을 포함하여 10시간이면 검출이 가능함을 알 수 있었다. 식품에서의 실증실험을 위하여 시중에서 판매되고 있는 신선편이 양배추를 구하여 25 g에 1~10 cfu의 수준으로 S. Typhimurium을 인위접종한 후 real-time PCR 방법과 식품공전방법으로 검출하였을 때 두 방법 모두 동일하게 30개중 29개 시료에 대하여 음성을 나타내었다.

• ALGAE
• /
• 제34권1호
• /
• pp.7-21
• /
• 2019

The genus Heterocapsa is one of the major dinoflagellate groups, with some of its species having worldwide distributions. However, prior to the present study, the phototrophic species Heterocapsa minima has been reported only from the northeast Atlantic Ocean. Recently, H. minima was found in the Korean waters, and a clonal culture was established. This culture was used to examine the morphology of the Korean strain H. minima HMMJ1604 through light and scanning electron microscopy, as well as for its genetic characterization. Furthermore, to determine the nationwide distribution of H. minima in Korea, its abundance was quantified in the waters of 28 stations in all four seasons in 2016-2018 using the quantitative real-time polymerase chain reaction method. The overall morphology of H. minima HMMJ1604 was very similar to that of the Irish strain H. minima JK2. However, the Korean strain had five pores around the pore plate, whereas the Irish strain had six pores. When properly aligned, the sequences of the large subunit and internal transcribed spacer regions of the ribosomal DNA of the Korean strain were identical to those of the Irish strain. This species was detected in the waters of 26 out of 28 stations, but its abundance was greater than $1.0cells\;mL^{-1}$ at 8 stations. The highest abundance of H. minima was $44.4cells\;mL^{-1}$. Although this species was found in all seasons, its abundance was greater than $1.0cells\;mL^{-1}$ when the water temperature and salinity were $10.9-25.0^{\circ}C$ and 17.5-34.1, respectively. To the best knowledge, the present study reported for the first time that H. minima lives in the Pacific Ocean and is widely distributed in the Korean waters.

• 한국응용과학기술학회지
• /
• 제39권6호
• /
• pp.916-923
• /
• 2022

창원시의 3개 지점(남천, 창원천, 청운지)에서 물 시료를 채취하고, 채취한 시료로부터 genomic DNA를 분리하였다. 분리된 DNA와 class A extended-spectrum beta-lactamase(ESBL) 유전자 5가지(bla_OXA-1, bla_SHV, bla_TEM, bla_CTX-M-1, bla_CTX-M-9)를 target으로 하는 primers를 사용하여 quantitative PCR을 수행하였다. 시료를 채취한 지점별로 ESBL 유전자들의 수와 비율에서 확연한 차이가 있음을 알 수 있었다. 남천의 경우 DNA 30ng당 ESBL 유전자가 1.93×10⁶ copy나 존재하는 데에 반해 창원천의 경우에는 1.47×10⁵ copy 그리고 청운지에는 9.5×10³ copy 밖에 존재하지 않았다. 흐르는 하천인 남천과 창원천에서는 각 ESBL 유전자들의 비율에서 큰 차이가 없었다. 즉, 남천에서는 bla_OXA-1 유전자가 65.3%, bla_CTX-M-1 유전자가 33.6%를 차지하여서 이 두 유전자가 전체 ESBL 유전자의 99% 가까이를 차지하고 있었다. 창원천에서도 bla_OXA-1 유전자가 64.1%, bla_CTX-M-1 유전자가 19.1%를 차지하므로 이 두 유전자가 전체의 83% 이상을 차지하고 있었다. 하천과 다르게 폐쇄된 환경인 청운지 연못에서는 내성세균들의 총량 자체가 다른 두 하천에 비해서 월등하게 적었다. 또한 내성 세균의 비율도 달라서 bla_CTX-M-1 유전자가 전체의 87.5%, 그리고 bla_CTX-M-9 유전자가 9.8%를 차지하고 있었다.

• 대한환경공학회지
• /
• 제29권8호
• /
• pp.895-903
• /
• 2007

매립지를 직접 생태학적으로 모니터링하는 방법을 개발하고자, 매립지 내의 생화학적 반응에 관여하는 세균들과 효소의 양을 정량함과 동시에 지하수 수질인자와 상호 연관성을 조사하여 생태학적 인자와의 연계 이용 가능성을 평가하였다. 이를 위하여 4개의 매립 종료된 비위생 매립지(천안(C), 원주(W), 논산(N), 평택(P) 매립지)에서 계절별로 지하수 시료를 채취하였으며 동시에 16S rDNA 방법을 사용하여 미생물 다양성을 분석하였다. 이를 기반으로, 매립지에서 주로 발견되는 세균과 효소를 대표하는 유전자를 정량하기 위한 특이 프라이머 쌍을 제작하였으며 상관계수에 기초하여 수질인자와 유전자 지표 인자간의 정량적 관련성을 비교하였다. 그 결과 DSR(황환원 세균) gene과 BOD(생화학적 산소요구량)사이의 상관관계는 0.8 이상인데 반해 NSR(질산화 세균-Nitrospira sp.) gene과 질산성 질소는 0.9 이상이었다. 안정화지표(BOD/COD)와 MTOT(메탄 산화 세균), MCR(Methyl coenzyme M reductase), Dde(Dechloromonas denitrificans) gene들은 0.8 이상의 상관관계를 가졌으나 3가 철과 Fli(Ferribacterium limineticm) gene은 0.7로 낮았다. MTOT gene의 경우, BOD/COD과의 관련성이 100%에 가깝게 높았다. 또한, 혐기성 유전자들(nirS-아질산 환훤효소, MCR, Dde, DSR)과 DO 역시 0.8 이상으로 나타나 일반적인 매립지 혐기성 반응들이 DO에 크게 의존함을 보였다. 결론적으로 분자생물학적 조사와 수질인자가 높은 상호연관성이 있었으며 real-time PCR이 전통적인 모니터링 인자들과 동시에 상호 보완적으로 모니터링에 사용됨으로써 매립지안정화 및 주변 영향을 평가하는데 효율적으로 사용 될 수 있음을 알 수 있었다.

• 대한소아치과학회지
• /
• 제25권2호
• /
• pp.400-420
• /
• 1998

We already know that it is very difficult to obtain an "isolated field" for direct bonding during the surgical exposure of unerupted teeth. The aim of this in-vitro study is to simulate the clinical situation of forced eruption and to evaluate the tensile strengths of preligatured button with several types of contamination which can happen during the surgical exposure of unerupted teeth. Four orthodontic direct bonding systems were used. ($Ortho-One^{TM}$, $Rely-a-Bond^{(R)}$, $Ortho-Two^{TM}$, Phase $II^{(R)}$) Each material was divided into four groups(n=20) : Group 1. (Control, no contamination), Group 2. (Rinse etching agent with saline instead of water), Group 3. (Blood contamination of etched surface for 30 seconds), Group 4. (Blood contamination of primed surface for 30 seconds) 320 bovine anterior permanent teeth were divided into the above mentioned 16 groups. Enamel surface was flattened and ground under water coolant. Pre-ligatured buttons were prepared to the same form. (Cut 0.25 ligature wire 10 cm in length. Twist the ligature wire 30 times clockwise. Mark the wire 15mm and 35mm points from button. Make a loop sticking two points together and twist the loop 6 times counterclockwise.) The bonded specimens were stored at $37^{\circ}C$ saline solution for 3 days. Then the tensile strength of each sample was measured with Instron universal testing machine, crosshead speed of 0.5mm/min. The following results were obtained: 1. As compared to control groups (Group 1) of each material, Rely-a-Bond had a significantly lower mean tensile strengths than other material. (p<0.01) 2. In Group 2. of Ortho-One and Rely-a-Bond, the mean tensile strengths decreased about 7.7% and 11.1%, respectively with statistical significances. (p<0.05) 3. In Group 2. of Ortho-Two and Phase II, the mean tensile strengths did not decrease. 4. In Group 3. of Ortho-One, Rely-a-Bond, Ortho-Two, and Phase II, the mean tensile strengths decreased about 60.8%, 56.1%, 60.2%, and 46.0%, respectively with statistical significances. (p<0.01) 5. In Group 4. of Ortho-One and Rely-a-Bond, the mean tensile strengths did not decrease. 6. In Group 4. of Ortho-Two and Phase II, the mean tensile strengths were decreased about 20.95% and 22.28%, respectively with statistical significances. (p<0.01) There were formations of a hump shaped mass from bonding resin under blood contamination which disturbed direct bonding procedure. According to Reynolds, the proper bond strength for clinical manipulation should be at least 45N or about 4.5Kg.F. According to these results, it can be concluded that Ortho-One could be used during surgical exposure of unerupted teeth. In any case, blood contamination of the etched surface should be avoided, but the blood contamination of primed surface of Ortho-One may not decrease bond strength. Just 'blowing-out' is enough to remove blood from primed surface of Ortho-One. You can verify the clean surface of the primer of Ortho-One after blowing out the blood contamination.

• 구강회복응용과학지
• /
• 제29권1호
• /
• pp.37-44
• /
• 2013

근관치료 후 적절한 치관부 밀폐를 위해 레진을 이용한 코어수복방법이 현재 많이 사용되고 있다. 하지만, 근관치료 과정에서 사용되는 NaOCl이나 EDTA같은 근관세척제는 레진 접착에 영향을 주는 것으로 알려져 있으며, 이에 관한 많은 연구들이 이루어져 왔다. 본 연구에서는 ethanol wet bonding을 치수강 상아질에 적용 시에 NaOCl과 EDTA가 결합강도에 미치는 영향에 대해 조사하였다. 30개의 인간 대구치로부터 총 60개의 시편을 얻었고, 이를 무작위로 4개의 군으로 분류했다. G1: 증류수로 세척후 증류수로 마무리 세척, G2: NaOCl로 세척 후 NaOCl로 마무리세척, G3: NaOCl로 세척 후 EDTA로 마무리세척, G4: NaOCl로 세척 후 EDTA로 마무리세척하고 접착과정에서 산부식과정 생략. 접착과정은 인산부식 후 에탄올의 농도를 50%, 70%, 80%, 95% 그리고 100%로 순차적으로 증가시켜가면서 상아질을 탈수시키고 에탄올에 적셔지도록 하였다. 프라이머는 HEMA가 포함되지 않은 상용화된 접착제인 ALL-BOND 3 RESIN과 에탄올을 반반씩 섞어 만들었다. 프라이머 적용 후 ALL-BOND 3 RESIN을 접착제로 사용하였다. 저점도 복합레진을 이용하여 6mm 두께로 적층충전한 후 빔 형태로 잘라 미세인장결합강도 실험을 하였다. NaOCl 처리한 그룹은 미세인장결합강도에 통계적으로 유의한 차이를 보여주지는 않았지만 낮은 평균값을 보여주었다(p=0.052). NaOCl 처리 후 1분간 EDTA로 처리한 그룹은 다른 그룹보다 유의하게 높은 결합강도를 보여주었다(p<0.05). EDTA 처리가 결합강도를 향상 시켰지만, 산부식 과정을 생략할 경우 유의하게 낮은 결합 강도를 보여주었으며, 이는 EDTA처리가 산부식 과정을 대신할 수는 없다는 것을 보여준다.