복합레진 수복물 수리 시 접착제 적용방법이 전단결합강도에 미치는 영향

오희경 Graduate School Dankook University. 2020 국내석사

이 실험의 목적은 오래된 복합레진과 새로운 복합레진 사이의 전단결합강도 측정 시 새로운 레진을 적용하기 이전 universal adhesive의 적용 방법(접착제를 여러 번 도포하는 것과 중합 여부)이 결합강도에 어떤 영향을 미치는지 평가하는 것이다. 78개의 실린더 형태의 복합레진 시편(Filtek Z350 XT)을 준비하여 일주일 동안 증류수에 보관 후 thermocycling(5,000 cycles, 5- 55℃)을 시행하여 오래된 레진 기질로 사용하였다. 400-grit의 실리콘 카바이드 샌드 페이퍼를 이용하여 표면을 거칠게 만든 후 37% 인산을 이용하여 산 부식을 시행하고, 표본을 적용하는 접착제에 따라 동등하게 두 그룹으로 분류하였다. (Single Bond Universal and Prime & Bond Universal) 각 그룹은 접착제의 적용방법에 따라 세 개의 하위 그룹으로 나누었다. (n=13) ⑴ 1회 적용 후 중합 ⑵ 1회 적용 후 미중합 ⑶ 3회 적용 및 중합. 같은 회사의 복합레진을 이용하여 수리 과정을 시행하였다. 증류수에 24시간 보관한 이후 각 표본에 대하여 전단결합강도 시험을 시행하였고, 자료를 통계적으로 분석하였다. (Two-way ANOVA, One-way ANOVA, independent t-test, P<0.05) 실체 현미경을 이용하여 파절 유형을 분류하고, 주사 전자 현미경을 이용하여 접착 계면의 결합 양상을 관찰하였다. 이원분산분석에서 접착제의 종류가 유의한 요소로 나타났다. Single Bond Universal을 사용했을 때의 결합강도는 Prime&Bond universal을 사용했을 때의 결합강도보다 더 높으며 가장 높은 평균 전단결합강도는 Single Bond Universal을 한 번 바르고 중합했을 때에 나타났다. 여러 번의 접착제 도포는 접착층의 두께를 유의하게 증가시켰지만 전단결합강도에는 유의한 영향을 미치지 않았다. 파절 유형은 주로 오래된 레진 기질 내의 cohesive failure로 나타났다. 견고한 결합강도를 얻기 위해 적절한 접착제를 선택하여 적용하는 것이 중요하다. Z350 XT nanocomposite 수복물을 수리하는 데에 있어 Single Bond Universal을 사용하는 것이 Prime&Bond Universal보다 더 높은 전단결합강도를 보이며 접착제의 추가 도포는 단지 접착층의 두께만을 증가시키고 전단결합강도에는 유의한 영향을 미치지 않았다. The purpose of this in vitro study was to evaluate the effect of application method of universal adhesives on the shear bond strength between aged and repaired composites applied with different thickness that were cured or left uncured when fresh composite was placed. A total of 78 cylinder shaped composite specimens (Filtek Z350 XT) were prepared, stored in distilled water for a week followed by thermocycling (5,000 cycles, 5℃ to 55℃), and served as substrates. They were mechanically roughened using 400-grit silicon carbide sandpapers and etched with phosphoric acid. After surface treatment, samples were equally divided into two groups: group A, Single Bond Universal (SU, 3M ESPE), and group B, Prime & Bond Universal (PB, Dentsply). Each group was subdivided into three subgroups (n=13) according to the application methods. ⑴ 1 coat + curing ⑵ 1 coat + uncuring ⑶ 3 coats + curing. They were repaired using the same composite resin. After storage for 24h in distilled water, specimens were subjected to a shear bond strength (SBS) test and the data (MPa) were statistically analyzed by two-way ANOVA to demonstrate the effects of adhesive and application method as well as their interaction. Specimens were examined with a stereomicroscope to analyze fracture mode and scanning electron-microscopy to observe the interface. Bonding agent material was significant factor. Bond strengths achieved with SU were higher than with PB. The highest bond strength was obtained by 1-coat application of SU with curing. Multi-layer application resulted in an increase in adhesive layer thicknesses, but there is no significant difference in SBS values. Failure mode was predominantly cohesive in old composites. Application of an adequate bonding system plays a important role in achieving reliable repair bond strengths. Groups with SU showed higher SBS than groups with PB and the application of additional layers increased the adhesive layer thickness but do not significantly affect SBS.

Effect of MoS2 Catalyst and H-donor on Catalytic Heavy-oil Upgrading

박한별 Dankook University Graduate School 2018 국내석사

This study includes the effect of tetralin and MoS2 catalyst on catalytic heavy-oil upgrading. First, the effects of tetralin as an H-donor on the reactivity of asphaltenes in a petroleum pitch were investigated under thermal cracking or catalytic hydrocracking conditions at 693K and 10.0 MPa N2 or H2. Reaction temperatures, pressures, and tetralin contents were varied to examine the reactivity of asphaltenes. Thermal cracking of the petroleum pitch led to a considerable amount of coke formation, close to 53.7wt%, but the addition of tetralin reduced the coke formation down to 23.6wt%. The coke formation was considerably reduced to 10.3wt% in the catalytic hydrocracking condition, and was not formed in the presence of tetralin. Kinetic studies on the catalytic hydrocracking of petroleum pitch in the absence or presence of tetralin demonstrated that the addition of tetralin, showing an increase in the hydrogen transfer capacity, contribute to the marked performance of hydrocracking of the petroleum pitch in the presence of dispersed MoS2 catalyst. Secondly, the alumina supported MoS2 catalysts for heavy-oil recovery were investigated. In order to design a suitable MoS2 catalyst for hydrocracking (HCK) of vacuum residue (VR), various factors of NiMo/γ-Al2O3 catalysts influencing the activity in VR HCK were investigated including Ni promotion, P addition, loading amount of Mo, and porosity of γ-Al2O3 support. Activity tests were conducted in a autoclave batch reactor at 693K and 10~12 MPa H2 for the VR HCK in the presence of 0.26wt% catalyst (0.12 g) and 33.0wt% tetralin (15 g). When Mo loadings on γ-Al2O3 increased from 4wt% to 16wt%, the asphaltene conversion increased from 59.8% to 65.8%, but the improvement width was gradually reduced. The Ni-promotion effect on Mo/γ-Al2O3 showed a synergistic effect in hydrodesulfurization (HDS), but did not significantly affect the asphaltene conversion. The P addition increased the reducibility of MoO3 and had negative effects on asphaltene conversion. The increase in porosity of γ-Al2O3 significantly improved the asphaltene conversion from 62.9% to 68.5% with the enhanced catalytic performance. Further, these MoS2 catalysts were also applied to the HDS of light cycle oil (LCO) in a continuous fixed-bed reactor and achieved the highest HDS conversion of 75.6% when using citric acid-modified NiMoS2 catalyst. On the other hand, unlike VR HCK, the activity enhancement by porosity of catalysts was insignificant. 본 연구는 중질유의 고도화에 대한 수소공여체의 역할 및 효과 입증과 MoS2촉매 설계인자 규명을 연구 대상으로 하였으며, 그 결과를 요약하면 다음과 같다. 첫째, 대표적인 수소공여체로 알려진 테트랄린이 아스팔텐의 반응성에 미치는 영향에 대하여 알아보기 위해 693K의 반응온도와 10.0 MPa 의 반응압력하에서 열분해반응과 수소첨가분해반응평가를 진행하여 테트랄린의 아스팔텐 반응성 증진 효과를 확인하였다. 특히, 수소첨가분해반응에서 테트랄린과 아스팔텐의 반응성 사이의 작용 메커니즘을 이해하고 상관관계를 규명하기 위하여 반응온도, 반응압력, 테트랄린의 함량을 공정 변수로 설정하여 영향을 살펴보았다. 반응물과 생성물은 GC-SIMDIS, GC-FID, TGA, EA-CHNS, 용매추출법 등의 분석방법을 활용하여 정성분석과 정량분석을 진행하였다. 아스팔텐의 열분해반응에서는 무려 53.7%의 코크가 생성되었으나, 테트랄린을 첨가한 결과 코크생성량이 23.6%로 감소되었다. 아스팔텐의 수소첨가분해반응에서의 코크생성량은 10.3%로 상당히 낮게나타났으며, 테트랄린을 첨가한 경우 코크가 생성되지 않는 것으로 나타났다. 표준조건 (693K, 10.0 MPa, 4시간반응)에서 테트랄린 존재 유무에 따른 아스팔텐의 수소첨가분해반응에 대한 반응속도론적 분석을 통하여 테트랄린이 아스팔텐의 코크 전환 반응속도를 저감하고 경질화 반응경로를 활성화하는 역할을 하는 것을 확인하였다. 두 번째, 중질유의 수소첨가분해반응에 적합한 MoS2계열담지촉매의 설계 인자 규명에 관한 연구를 수행하였다. MoS2계열담지촉매의 촉매 활성에 영향을 주는 것으로 알려진 대표적인 설계 인자를 선정하였으며, 증진제(Ni)효과, 첨가제(P)효과, 몰리브데늄의 담지량에 따른 영향, 알루미나 지지체의 다공성에 따른 영향을 살펴보았다. 제조한 촉매는 BET, EXAFS, TPR, XRD, TEM등의 분석기법을 활용하여 특성을 확인하였으며, 활성평가는 693K, 10~12 MPa조건에서 0.26wt%의 촉매와 33.0wt%의 테트랄린 용매 존재 하에 감압잔사유를 반응물로 하여 회분식 반응기 내에서 진행되었다. 반응생성물에 대해서는 용매추출법, GC-FID, GC-SCD, ED-XRF등의 분석기법을 활용하여 정성, 정량분석을 수행하였다. 몰리브데늄의 담지량을 4wt%, 8wt%, 16wt%단위로 증가시켰을 때, 아스팔텐의 전환율은 59.8%, 62.7%, 65.8%로 상승하였지만 상승폭은 점차 감소하였다. MoS2촉매에 니켈첨가는 수첨탈황반응에는 상당한 시너지효과를 보였지만 아스팔텐의 반응성에는 크게 영향을 주지 않았다. 인(P)의 첨가는 삼산화몰리브데늄(MoO3)의 부분환원력을 증가시켜서 Type-II상의 형성이 유도됨을 확인하였지만, 아스팔텐의 전환에는 역효과를 나타냈다. 반면, 세공이 2배가량 더 발달한 담체를 적용한 결과 아스팔텐전환율이 62.9%에서 68.5%로 높게 상승하였으며, 중질유의 수소화반응과 아스팔텐의 반응성향상에 가장 큰 효과를 나타냈다. 중질유의 수첨분해반응에 있어서는 촉매의 활성상보다 담체의 세공이 중요한 설계인자임을 확인하였다. 셋째, 다양한 조건에서 합성한 MoS2촉매들을 연속식반응기내에서 접촉분해유분(LCO)의 수소첨가탈황 반응에도 적용하였다. 촉매준비과정에서 시트르산을 적용한 NiMoS2 촉매가 접촉분해유분에 대하여 75.6%로 가장 높은 탈황전환율을 보였다. 이는 시트르산 첨가에 의한 Ni-Mo-S 활성상 형성과 상관된 결과로 해석되었다. 이와 같은 결과를 통하여 상대적으로 경질한 LCO와 같은 유분에 대해서는 담체의 표면특성보다 촉매의 활성상 형성여부가 반응성을 결정하는 주요 인자임을 확인하였다.

Increased Oral Bioavailability of Tacrolimus by Supersaturable Self-emulsifying Drug Delivery System

이대로 Graduate School Dankook University 2017 국내석사

A novel supersaturable self-emulsifying drug delivery system (S-SEDDS) was developed to enhance the oral absorption of Tacrolimus (FK506), a poorly water-soluble immunosuppressive agent. A S-SEDDS was prepared by incorporating Soluplus (polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer) as a precipitation inhibitor with a conventional SEDDS vehicle consisted of Capmul MCM, Cremophor EL and Transcutol HP (FK506 : vehicle : Soluplus = 1 : 15 : 1 w/w). The supersaturable formulation formed uniform spherical microemulsions with less than 70 nm upon contacting with simulated gastric fluid (pH 1.2). Moreover, the dissolution rate from S-SEDDS was rapidly elevated to approximately 99% at 30 minute, maintaining over 84% for 24 hours. The dissolution profile of the S-SEDDS was even comparable with that of a conventional SEDDS containing four times more vehicle than S-SEDDS. Moreover, in an in vivo pharmacokinetic study in rats, there were no statistically difference (P > 0.05) in the maximum blood concentration (Cmax) and area under the curve (AUC0–24hours) between S-SEDDS and conventional SEDDS. The results of this study suggest that the novel supersaturable system may be a promising approach for improving oral absorption of FK506, which oils and surfactants reducing gastrointestinal (GI) irritations caused by excessive amounts of oil and surfactants.

Preparation and Applications of Thermo- Responsive Copolymers as a Smart Drug Delivery System

Seo Jae-Won Graduate School Dankook University 2016 국내박사

Part I-A 본 연구는 N-isopropyl acryl amide(NIPPAm)과 1-butyl-3-vinylimidazolium bromide([BVIm]Br)를 라디칼 중합방법에 의하여 부분적 양전하를 갖는 온도 감응성 공중합체를 합성하였다. 합성 된 공중합체들의 NIPAAm 단량체와 BVIm 단량체의 몰비는 95:5, 90:10, 85:15 그리고 80:20으로 각각 합성되었다. 각각 다른 농도의 imidazolium moiety의 존재를 1H NMR을 통하여 확인하였다. 합성된 공중합체의 LCST (저임계 상전이 온도; lower critical solution temperature) 수치는 UV-Vis spectrophotometer를 이용하여 확인 하였으며 imidazolium moiety의 농도가 증가함에 따라 LCST 수치 또한 증가함을 확인 하였다. 또한 imidazolium moiety의 농도가 증가는 수용액 상태에서 미셸표면 전하의 증가를 (+3.4 에서 +21.3 mV, pH 7) 나타냈고 상온에서의 미셸 사이즈의 증가를 보였다. 변화 된 미셸 사이즈의 차이는 25 ~ 50 oC의 온도 범위에서 211.5 에서 69.1 그리고 325.4 에서 171.2 nm로 각각 나타났다. 이러한 결과들은 열감응성 고분자의 LCST 값을 단지 imidazolium unit (BVIm)의 농도로 조절 가능함을 보였다. 더 나아가서, 합성 된 p-NIBIm10과 15은 고정적인 양전하를 갖고 있으며, 정상과 병변부위의 온도 변화 범위인 37 ~ 40oC에서 작용 가능한 고분자 물질로써 지능형 약물 또는 유전자 전달체로의 응용 가능성이 높다고 판단된다. Part I-B 본 연구에서는 다양한 LCST 값을 갖는 이온성 열감응 공중합체를 합성하였고, 다양한 LCST 값은 음이온의 종류에 따라 조절되었다. 합성된 공중합체는 이온성 부위인 imidazolium moiety를 갖고 있는 poly(NIPAAm-co-BVIm), [p-NIBIm]+[Br]-이며 이를 기반으로 짝이온을 변화시킴으로써 [p-NIBIm]+[X]- (X = Cl, AcO, HCO3, BF4, CF3SO3, PF6, SbF6)을 생성시켰다. 생성 된 공중합체의 화학적 특성은 nuclear magnetic resonance spectroscopy (1H-NMR), Fourier-transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), 그리고 thermogravimetric analysis (TGA)을 통해 분석하였다. 또한, 다양한 LCST값, 미셸 크기, 그리고 표면 전하를 Ultraviolet-visible spectrophotometer와 Zeta (ξ) sizer를 이용하여 측정 하였으며, LCST 값은 39oC에서 52 oC까지 넓은 영역에 걸쳐 나타났다. 표면 전하 수치인 Zeta (ξ) potential 값은 pH = 7 에서[p-NIBIm]+[X]- (X = Cl . Br)는 +9.7 mV 값을 보였으며, +2.0 mV for [p-NIBIm]+[X]- (X = PF6 . SbF6)는 감소 된 +2.0 mV의 값을 보였다. 미셸 크기의 변화는 서로 다른 음이온의 종류에 따라 [p-NIBIm]+[Br]-; 181.2 nm (또는 2.49 × 10-17cm3) 에서 [p-NIBIm]+[CF3SO3]-; 229.2 nm (또는 5.04 × 10-17cm3) 로 증가함을 보였다. 이결과는 온도에 따른 미셸의 크기 감소의 값은 음이온의 종류에 따라 확연한 차이를 보였다. 본 연구에서의 가장 중요한 사실은 본 열감응성 고분자의 물리화학적 특성이 (LCST, 미셸 사이즈, 그리고 표면 전하등) 음이온을 변화시킴으로써 조절 가능 하다는 점이다. 이러한 특성은 본 열감응성 고분자가 지능형 약물 전달체로의 응용이 가능하다고 판단되는 점이다. Part II 최근에는 소장 (또는 대장)을 목표로 한 특이적 약물 전달 시스템의 치료 효율을 극대화하고 부작용을 줄이기 위한 연구가 크게 증가하고 있다. 그러나, 인간 창자의 복잡한 환경에 대한 요구를 충족하는 예는 소수에 불과했다. 본 연구에서는 염기성 pH와 온도에 감응하는 공중합체를 합성 하였고, 합성된 공중합체가 pH 1-8의 범위, 그리고 온도 25-42 oC 범위에서의 약물 전달 기능에 대한 특성을 in vitro 상에서 확인 하였다. 염기성 공중합체는 N-isopropylacrylamide (NIPAAm)과 N-vinylimidazole (VIm)의 라디칼 중합 방법으로 합성 되었다. 15 mol%의 염기성 VIm 유닛을 갖는 합성된 공중합체는 (p-NIVIm) pH=7에서 +9.1 mV 표면 전하를 나타냈으며, ~1.0의 낮은 pH인 위장의 pH 범위에서 36.5-42 oC의 높은 LCST를 보였고, ~8.0의 소장 또는 대장의 pH 범위에서는 35.8-38.2 oC의 LCST를 보였다. pH/온도에 의존하는 미셸 구조의 형태와 크기 변화는 건조 또는 습윤 상태에서 SEM과 ZetaSizer를 이용해 확인하였다. 모델 단백질을 (BSA) 이용하여 신체 조건인 37 oC 그리고 pH 1-8 범위에서 저장 및 방출을 확인 하였다. p-NIVIm의 37 oC/pH 1에서의 약물 저장 능력 (LC)와 저장 효율 (LE)은 각각 공중합체 1 mg 당 0.231 mg 그리고 92.4%였다. 상기 약물 전달체는 낮은 pH 값인 1에서 느린 약물 방출을 보였으며(~0.084 mg; ~35 %), 높은 pH 값이 8에서는 순간적인 약물 방출을 보였다(~0.177 mg; ~73%). 합성 된 pH 감응성 단백질 저장/방출 특성은 새로운 소장 (또는 대장)에 특이적으로 약물을 전달 할 수 있는 재료로 응용할 수 있을 것이다. Part III 본 연구에서는 이상적인 약물 전달체를 mesoporous silica nanoparticle (MSN) 표면에 1-butyl-3-vinyl imidazolium bromide (BVIm)와 N-isopropyl acrylamide (NIPAAm)을 이용하여 공중합체를 형성 시켰다. 표면을 코팅하고 있는 공중합체 (poly(NIPAAm-co-BVIm) (p-NIBIm))의 두께는 2.5 nm와 5 nm 범위에서 조절 되었고, 이는 반응액에서의 단량체와 MSN의 조성으로 조절되었다. 마지막으로 합성된 지능형 약물 전달체는 p-MSN2.5과 p-MSN5.0으로 명명 하였다. Mesoporous-silica-nanoparticle (MSN) 코어오 표면 코팅 된 p-NIBIm 층의 중요한 역할은 약물 전달 (또는 저장) 그리고 다공의 캡핑과 온도에 따른 ON/OFF 역할이다. 지능형 캡핑 재료인 공중합체의 swelling- 또는 shrinking- 감응은 10 oC에서 40 oC의 온도 범위에서 나타난다. 상기 재료의 약물 저장과 방출 패턴은 모델 약물인 cytochrome c를 사용하였다. 이러한 발전 된 약물 전달체는 흥미로운 약물 저장과 방출특성은; p-MSN2.5와 p-MSN5.0가 각각 10 oC에서 26.3%와 19.8% 그리고 40 oC에서 cytochrome C의 방출은 3 일과 4 일 동안 동안 >95%의 방출을 보였다. 재료의 세포 독성은 <0.125 mg/mL의 범위에서 약물 없이 진행 하였으며 human breast-cancer cells (MCF-7) 세포를 사용 하였다. 이 결과들은 본 재료가 특정 부위를 목표로 한 지능형 약물 전달체로써의 응용이 가능함을 보였다. Part I-A A series of stimuli-responsive copolymers (p-NIBIm) of N-isopropylacrylamide (NIPAAm) and 1-butyl-3-vinyl imidazolium bromide (BVIm) with various BVIm monomer concentrations such as 5, 10, 15, and 20 mol% were synthesized by radical copolymerization. The different concentrations of the imidazolium moiety within the resulted copolymer chain were determined by 1H NMR analysis. The LCST (lower critical solution temperature) values of the copolymers that were checked by UV-Vis spectrophotometer increased with the increasing concentration of the imidazolium moiety and were ranged from 36 up to 46 oC. According to the increasing concentration of the imidazolium moiety, the p-NIBIm copolymers also showed increasing zeta potential values (from +3.4 up to +21.3 mV) at pH 7, increasing initial and final micelle sizes (from 211.5 to 69.1 and from 325.4 to 171.2 nm), respectively, at 25 and 50 oC, and increasing contraction levels of micelle volumes between 25-50 oC (from 2.69×10-18 up to 8.67×10-18 cm3). These results demonstrate that it is possible to tune the LCST value of a temperature-responsive copolymer only by changing the imidazolium unit (BVIm) concentration within the copolymer chain. Moreover, p-NIBIm10 and 15 among the prepared copolymers could demonstrate high applicability in various endeavors such as on a target drug or in a gene delivery system. Part I-B An ionic thermo-responsive copolymer with multiple lower critical solution temperatures (multi-LCSTs) has been developed, and the multi-LCSTs were easily changeable according to the various counter anion types. The multi-LCST values were achieved by introducing an ionic segment with an imidazolium moiety within the p-NIPAAm polymer chain to produce poly(NIPAAm-co-BVIm) copolymers, [p-NIBIm]+[Br]ꠑ, and changing the counter anion type to produce [p-NIBIm]+[X]- (X = Cl, AcO, HCO3, BF4, CF3SO3, PF6, SbF6). The as-prepared temperature-responsive copolymers were physicochemically characterized via proton nuclear magnetic resonance spectroscopy (1H-NMR), Fourier-transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). Their various LCST values, micelle sizes, and surface charges were determined using an Ultraviolet-visible spectrophotometer and a Zeta (ξ) sizer, which were fitted with temperature and stirring control. The copolymers showed a broad LCST spectrum between 39 oC and 52 oC. The Zeta (ξ) potential values at a pH = 7 decreased from about +9.7 for [p-NIBIm]+[X]- (X = Cl . Br) to about +2.0 mV for [p-NIBIm]+[X]- (X = PF6 . SbF6). The micelle size (or volume) of the copolymers with different anionic species gradually increased from 181.2 nm (or 2.49 × 10-17cm3) for [p-NIBIm]+[Br]- to 229.2 nm (or 5.04 × 10-17cm3) for [p-NIBIm]+[CF3SO3]-, showing a clear effect of the anion on themicelle size (or volume) at a constant temperature, such as body temperature. The fact that the most important physicochemical properties for the thermo-responsive copolymers, such as the LCST value, micelle size (or volume), and surface charge, could be easily controlled only through the anion exchange suggests these are highly applicable as ionic thermo-responsive copolymers in a drug (or gene, protein) delivery system. Part II In recent years there has been a significant increase in available strategies for developement of small intestine (and/or colon)-specific drug-delivery system to maximize the efficiency of therapeutic agents and to reduce side effects. However, only a few cases has fulfiled the needs to work in the complicate environments of the human intestinal tract. In this study, the preparation of a basic pH/temperature-responsive co-polymer and the characterizations of the in-vitro-drug delivery function in the pH range of 1-8 and in the temperature range of 25-42 oC were reported. The basic copolymer was prepared by radical copolymerization of N-isopropylacrylamide (NIPAAm) and N-vinylimidazole (VIm). The prepared copolymer (p-NIVIm) with 15 mol% concentration of the basic VIm unit and the surface charge of +9.1 mV at pH=7 was appeared to have the higher LCST (lower critical solution temperature) value such as 36.5-42oC in the stomach pH condition (~1.0) and the lower LCST value such as 35.8-38.2 oC in the small intestinal (and/or colon) pH condition (~8.0). The pH/temperature-dependent morphology- and micelle size- changes also were determined under dry and wet conditions, respectively, by SEM and ZetaSizer. The abilities to uptake a model protein (BSA) in body temperature and to release it in the conditions of 37 oC and pH 1-8 were determined. The drug loading capacity (LC) and efficiency (LE) of p-NIVIm at 37 oC/pH1 were 0.231 mg pro 1.0 mg copolymer and 92.4%, respectively. The drug carrier showed a slow release pattern in the low pH value of 1 (~0.084 mg; ~35 %) and then the sudden release pattern (~0.177 mg; ~73%) at the high pH of 8. The prepared copolymer with the pH-responsive protein-entrapping and -releasing behavior at body temperature will potentially be applied to be used as a novel small intestine (and/or colon) specific drug delivery system. Part III The preparation of the ideal smart drug-delivery systems were successfully achieved by the in situ co-polymerization of a vinyl group-functionalized mesoporous silica nanoparticle (f-MSN) with 1-butyl-3-vinyl imidazolium bromide (BVIm) and N-isopropyl acrylamide (NIPAAm) monomers. The thicknessof the capping copolymer layer, poly(NIPAAm-co-BVIm) (p-NIBIm), was controlled at between 2.5 nmand 5 nm, depending on the monomers/f-MSN ratio in the reaction solution. The finally obtained smart drug-delivery systems are named as p-MSN2.5 and p-MSN5.0 (MSNs integrated by 2.5 nm and 5 nm p-NIBIm layer in thickness). The key roles of the mesoporous-silica-nanoparticle (MSN) core and the p-NIBIm shell are drug-carrying (or containing) and pore-capping, respectively, and the latter has an on/off function that operates in accordance with temperature changes. According to the swelling- or shrinking-responses of the smart capping copolymer to temperature changes between 10 oC and 40 oC, the loading and releasing patterns of the model drug cytochrome c were studied in vitro. The developed system showed interesting performances such as a cytochrome C loading profile (loading capacity for3 h = 26.3% and 19.8% for p-MSN2.5 and p-MSN5.0, respectively) at 10oC and a cytochrome C releasing profile (releasing efficiency = > 95% within 3 days and 4 days for p-MSN2.5 and p-MSN5.0, respectively) at 40 oC. The cytotoxicity of the drug delivery systems, p-MSN2.5 and p-MSN5.0 (in the concentration range of <0.125 mg/mL without drug), for human breast-cancer cells (MCF-7) cells were minimal in vitro compared with that of a blank MSN. These results may be reasonably applied in the field of specified drug delivery.

Study on Bioplar and SCR-based ESD Protection Devices with High Robustness and Efficient Area using Floating Diffusion for High Voltage ICs

Jung Jinwoo Graduate School Dankook University 2016 국내박사

This thesis presents a bipolar junction transistor (BJT)-based electrostatic discharge (ESD) protection device and silicon-controlled rectifier (SCR)-based ESD protection device. Both NPN bipolar transistors and silicon controlled rectifier (SCR) structures are widely used as high-voltage ESD clamp protection devices due to its high current driving capability and small footprint characteristics. However, these devices are not suitable for high-voltage technology because of the latch-up issue and the high trigger voltage. In this thesis, therefore, we propose a BJT-based ESD protection device that has a high robustness, low on-resistance, and a small footprint characteristics for high-voltage applications. Also, the SCR-based ESD protection device has high robustness and area efficiency for 250 V applications. The BJT-based device was implemented by combining an SCR device with a BJT. The device was designed with three parameters, and its characteristics can be optimized by adjusting those parameters. Our proposed device was fabricated with a 0.18, µm 60 V Bipolar CMOS DMOS (BCD) process, and its characteristics were verified through transmission-line pulse (TLP) tests, DC breakdown voltage measurements, and ESD zapping tests. In addition, the stacked structure was designed by using a unit device to apply the 60 V applications. From the experimental results, the unit device has a trigger voltage of 29.4 V and a holding voltage of 22.4 V. The proposed device exhibited an extremely low on-resistance characteristic of about 0.5 ohm. In addition, most of the unit devices passed the human-body model (HBM) 8 kV and the machine model (MM) 800 V. In the case of the stacking device, the holding and trigger voltages increased linearly with the number of stacks; the three-stack device passed the HBM 8000 V at the board level. Therefore, the proposed device will provide high reliability for high-voltage applications. The SCR-based device was designed through a 1.0 µm DMOS Silicon-On-Insulator (SOI) process. The measurement result of the proposed SCR device showed that the device has high current drivability of 10A or higher, holding voltage of 250 V higher, and trigger voltage of 460 V, and it passed 8 kV HBM. The proposed SCR device is properly designed for the IC characteristics, and the device has more than 70% area reduction and more than four times high robustness compared to PMOS 19-stack device. Through these studies, the proposed devices are suitable for high voltage IC characteristics, and they have high robustness and area efficient characteristics.

Effects of Leptin on Osteoclast Generation and Activity : Leptin이 파골세포의 생성 및 활성에 미치는 영향

조상래 Graduate School, Dankook University 2003 국내박사

Leptin은 지방세포에서 생성되어 에너지 조절 호르몬으로 시상하부에 작용하며, 그 수용기가 여러 조직에 분포하며, 조혈작용, 면역작용 및 뇌 발달과 같은 여러 작용에 관여한다고 알려져 있다. 또한 leptin과 그 수용기가 조골세포에서 발현되며, leptin이 조골세포의 증식, 교원섬유 합성 및 석회화를 촉진하며, 파골세포의 생성을 억제함이 보고되었다. 따라서 leptin이 골대사에 관여하리라 여겨지나 그 정확한 기전은 알려져 있지 않아, 본 연구에서는 leptin이 파골세포의 생성 및 활성 기전에 미치는 영향을 관찰하였다. 마우스 골수세포를 분리하여 1,25-dihydroxy- cholecalciferol (1,25[OH]2D3) 및 prostaglandin E2 (PGE2)를 처리하여 파골세포의 분화를 유도하였고, receptor activator of NF-kB ligand (RANKL)을 처리하여 RAW264.7 세포로부터 파골세포의 분화를 유도하였으며, 동시에 leptin을 여러 농도로 처리하였다. 또한 leptin이 파골세포의 생성 및 활성에 미치는 효과가 PGE2에 의해 매개되는지 확인하기 위하여 cyclooxygenase 억제제인 indomethacin을 처리하여 그 효과를 확인하고, protein kinase C (PKC)의 활성과 관련되어 있는지 확인하기 위하여 PKC 활성 촉진제인 phorbol 12-myristate 13-acetate (PMA)와 PKC 억제제인 H7을 처리하여 그 효과를 확인하였다. 또한 leptin의 파골세포 생성 및 활성에 미치는 영향이 파골세포 생성 억제 인자인 osteoprotegerin (OPG)의 분비에 의한 것인지 확인하기 위하여, 조골세포를 배양하며 leptin을 처리한 후 OPG의 생성량을 측정하여, leptin이 파골세포의 생성 및 골흡수 기전에 미치는 영향을 관찰하였다. 그 결과 leptin은 골수세포로부터 1,25[OH]2D3 및 PGE2에 의해 유도된 파골세포의 생성 및 활성을 억제하였으며, RAW264.7 세포로부터 RANKL에 의해 유도된 파골세포의 생성 및 활성을 억제하였다. Indomethacin은 골수세포로부터 1,25[OH]2D3에 의해 유도된 파골세포의 생성 및 활성을 억제하였으며, leptin은 indomethacin에 의해 매개된 파골세포 생성 및 활성 억제효과에 영향을 미치지 못하였다. PMA는 골수세포로부터 1,25[OH]2D3에 의해 유도된 파골세포의 생성을 억제하였으며, leptin을 첨가한 경우 PMA에 의해 효과가 촉진되었다. H7은 골수세포로부터 1,25[OH]2D3에 의해 유도된 파골세포의 생성에 영향을 미치지 못하였다. Leptin은 조골세포로부터 파골세포 생성 억제 인자인 OPG 생성을 촉진하였다. 이상의 결과 leptin은 파골세포의 생성 및 활성을 억제하며, 골조직 대사의 조절에 관여하는 물질이라 여겨진다. Leptin, the product of the obese gene, is a circulating hormone secreted primarily from adipocytes. Several results suggest that leptin is important mediators of bone metabolism. The present study was undertaken to determine the effects of leptin on anti-osteoclastogenesis using murine precursors cultured on calcium-phosphate coated plates and on the production of osteoprotegerin (OPG) in osteoblastic cells. Additionally, this study examined the possible involvement of prostaglandin E2 (PGE2)/protein kinase C (PKC)-mediated signals on the effect of leptin on anti-osteoclastogenesis to various culture systems of osteoclast precursors. Osteoclast generation was determined by counting tartrate-resistant acid phosphatase positive [TRAP (+)] multinucleated cells (MNCs). Osteoclastic activity was determined by measuring area and number of resorption pits formed by osteoclasts on Ca-P coated plate. The number of 1,25-dihydroxycholecalciferol (1,25[OH]2D3)- or PGE2- induced TRAP (+) MNCs in the mouse bone marrow cell culture decreased significantly after treatment with leptin. The number of receptor activator of NF-kB ligand (RANKL)-induced TRAP (+) MNCs in M-CSF dependent bone marrow macrophage (MDBM) cell or RAW264.7 cell culture decreased significantly with leptin treatment. Indomethacin inhibited osteoclast generation induced by 1,25[OH]2D3 and dexamethasone, however, no significant differences were found in the leptin treated group when compared to the corresponding indomethacin group. Phorbol 12-myristate 13-acetate (PMA), a PKC activator, inhibited osteoclast generation induced by 1,25[OH]2D3. The number of TRAP (+) MNCs decreased significantly with treatment by PMA at concentrations of 0.01 and 0.1 μM in culture. Leptin inhibited PMA-mediated osteoclast generation. Isoquinoline-5-sulfonic 2-methyl-1-piperazide dihydrochloride (H7) had no effect on osteoclast generation induced by 1,25[OH]2D3. Cell culture treatment with leptin resulted in no significant differences in osteoclast generation compared to the corresponding H7 group. Indomethacin showed no significant effect on TRAP (+) MNCs formation from the RAW264.7 cell line. PMA inhibited TRAP (+) MNCs formation induced by RANKL in the RAW264.7 cell culture. H7 had no effect on osteoclast generation from the RAW264.7 cell line. There was no difference compared with the corresponding control group after treatment with leptin. 1,25[OH]2D3- or PGE2-induced osteoclastic activity decreased significantly with leptin treatment at a concentration of 100 ng/ml in mouse bone marrow cell culture. Indomethacin, PMA, and H7 significantly inhibited osteoclastic activity induced by 1,25[OH]2D3 in mouse bone marrow cell culture. No significant difference was found between the leptin treated group and the corresponding control group. The secretion of OPG, a substance known to inhibit osteoclast formation, was detected from the osteoblasts. Treatment with leptin resulted in significant increases in OPG secretion of osteoblastic cells. Taken these results, leptin may be a regulatory cytokines within the bone marrow microenvironment.

Genetic Diversity and Antioxidant Activities in Cucumis sativus Genetic Resources

루티투이 Graduate School Dankook University 2018 국내석사

Fruits of eighty-six cucumber accession were collected for analysis of total polyphenol content, total flavonoid content and antioxidant activity. The total polyphenol content ranged from 0.52 to 1.96 mg GAE/g of dry fruit at the mean of 1.25. In addition, the total flavonoid content ranged from 1.22 to 3.72 mg CE/g of dry fruit at the mean of 2.06. The IC50 for DPPH scavenging activity ranging from 360.0 to 1036 µg/ml in methanol extract at the mean of 589.36 There were 10 quantitative traits and 25 qualitative traits evaluated. At P=0.05, there were significant differences between cucumber germplasm collected from different continents for length of first 15 internodes, stem diameter, leaf lobe length, fruit peduncle length, and fruit weight. High significant coefficient variances were seen in the following traits: number of primary stem per plants, fruit peduncle length, fruit length, fruit weight, ratio of fruit length and fruit diameter. At P=0.01, length of first 15 internodes was positively correlated to leaf length (r=0.392), peduncle length (r=0.322), fruit length (r=0.345) and fruit weight (r=0.333), while the number of primary stems per plants was negatively associated to fruit length (r=-0.299). Leaf blade length had positive correlation to leaf lobe length (r=0.662), fruit length (r=0.302) and fruit weight (r=0.228), whereas placental diameter had negative correlation to leaf length (r=-0.245). Peduncle length was positively correlated to fruit length (r=0.280) and fruit weight (r=0.245). Fruit length was positively correlated to fruit weight (r=0.543), whereas it had negatively correlated to fruit diameter (r=-0.267) and placental diameter (r=-0.518). Fruit diameter had high correlation to placental diameter (r=0.734) and fruit weight (r=0.571). The principal components of 10 quantitative traits were evaluated. The first principal component (PC1) represented 47% of the variability. The second principal component (PC2) represented 27% of the variation. The Asian cucumber germplasm evenly distributed in the figure, while Europe and America cucumber germplasms were more located in the leaf hand side of the figure, indicating that they shared common characteristics. The Shannon-Weaver’s diversity index of the cucumber germplasm range from 0.05 to 1.50 at the mean of 0.81. The fruit traits had higher diversity index at the mean of 0.915, whereas the diversity index of leaf and flowers traits were 0.604 and 0.445 by the mean values, respectively. Cucumber (Cucumis sativus) is one of important fruit vegetable, which ranked third in term of total production area in 2014, after tomato and cabbage. Cucumber can be used for fresh eating, processing and cooking. In cosmetics, it has an excellent potential for cooling, healing and soothing to irritated skin, whether caused by sun, or the effects of a cutaneous eruption. Cucumber is one of very low calorie veggies, contain no saturated fats or cholesterol, a good source of dietary fiber, a very good source of K, and moderate anti-oxidants, which provide us with valuable antioxidant, anti-inflammatory, and anti-cancer benefits. Cucumber has a narrow genetic base, with genetic variability of only 3-8%, which are more susceptible to pests, diseases and environmental changes. In order to overcome the problems associated to limited genetic diversity, it is necessary to construct characterized gene banks. One-hundred twenty-three cucumber accessions collected from 28 countries of four different continents (Asia, Africa, America, and Europe) were experimented to evaluate the diversity in morphology, biology, EST-SSR markers and antioxidant activity; and to find out valuable traits from these cucumber accessions in order to use in breeding programs as well as in conservation, exploitation and improvement of cucumber genetic resources. The cucumber germplams were more diversity in term of morphology than molecular markers. For the fruit qualitative traits, the similarity coefficient of the cucumber germplasm varied from 0.45 to 1.00 with the mean similarity coefficient of 0.73. At the similarity coefficient of 0.674, the germplasm was divided into 10 groups. Group 1, 2 and 3 shared common characteristics of no fruit dot, while other groups presented dot in fruit at different distribution and density. Group 6 showed white ground color at both market stage and physiological ripeness stage. Meanwhile group 1, 5, 6 showed angular fruit shape in transverse section, round fruit shape in transverse section was seen in group 3, 4 and round to angular in group 10. Hair and pickles were both seen in groups 4 and 5, while group 3, 6, 8, 9, 10 showed pickles vestitures only. Genetic diversity of the cucumber germplasm were also evaluated by 28 pairs of EST-SSR markers. There were 9 pairs of primers showed polymporphism, occupied for 32.14%. The polymorphic primers detected from 2 to 4 alleles. Polymorphism information content (PIC) values ranged from 0.16 to 0.64 at a mean of 0.34, while the expected heterozygosity values varied from 0.18 to 0.64 with a mean of 0.43. For EST-SST markers, the mean similarity coefficient was 0.68 (range, 0.64-0.89). At the similarity coefficient of 0.832, the germplasm can be divided into 10 groups. Group 10 accounted for 90.35% of the germplasm. Group 1, 2, 3, 4, 5, 6, 8, 9 collected from Asia; Group 7 included accessions collected from Europe; Group 10 include 60 accessions from Asia, 17 accessions from Europe, 1 accession from Asia and 5 accessions from America.

Construction of the surface display vector for lactobacilli and the effect of porcine epidemic diarrhea viral (PEDV) antigens expressed on the surface of Lactobacillus plantarum SK156 on the immune responses of mice

채종표 Graduate School, Dankook University 2017 국내박사

Neonatal diarrhea is the main health problem among suckling and weaned piglets around the world. PEDV is one of the major causes of diarrhea in pigs, and is a disease that has been rapidly increasing in recent years in the United States and South Korea. Lactobacilli is the largest genus in the lactic acid bacteria (LAB) group. The LAB group consists considerably of probiotic microbes that are effective candidates for a vaccine antigen delivery system in the intestinal mucosa. To develop effective mucosal vaccine formulation against porcine epidemic diarrhea virus (PEDV) infection. Lactobacilli were isolated in order to construct a novel plasmid-based surface display system. Novel plasmid DNA was isolated from L. plantarum LP27 to construct pULP3, a lactic acid bacterial expression vector with an increased expression rate under bile conditions. β-glucuronidase assay showed a 15% ~ 48% increase in expression level of pLDH1, pEⅡDM, pPTSA and pHPRK promoter harbored vectors under the bile condition. In order to express PEDV antigens on the surface of recombinant SK156, the fusion gene was constructed by linking the signal peptide (SP) and cell wall anchor domain (CWA) of the slpA gene derived from L. acidophilus ATCC4356 strain with the selected PEDV membrane protien antigen determinants M1, M2 and M3. The surface-displayed recombinant plasmid pULP3:SPepitope:CWA was electroporated into L. plantarum, where expression and localization of SP-M1-CWA, SP-M2-CWA and SP-M3-CWA protein was confirmed by immunofluorescence assay, respectively. After intragastric administration to Balb/C mice, it was observed that live L. plantarum-expressing M1 and M3 epitope revealed stronger immunogenicity than the other epitopes (versus wild type SK156, p < 0.05). This means that the PEDV M1 and M3 epitopes can induce a much stronger mucosal and systemic immune response than other epitopes and wild-type SK156. This study confirmed that epitopes M1 and M3 displayed on L. plantarum SK156 surface could be utilized as new mucosal vaccines, even though Balb/C mice are not strongly susceptible animal models for PEDV. This therefore offers an important opportunity for vaccine development.

Comparative Analyses of Cell Surface and Extracellular Proteins in Lactobacillus spp.

봉오바곤베르나데트 Dankook University, Graduate School of Dankook Uni 2021 국내박사

Lactobacillus spp. are one of several species used as probiotics due to their health-promoting effects. Being generally regarded as safe, lactobacilli can be found in fermented food and as normal inhabitants of the animal gastrointestinal tract. For these reasons, lactobacilli have become ideal for addition to food products to increase their nutritional value. However, as potential probiotics, lactobacilli still need to be evaluated for their characteristics (e.g. beneficial genes, survival ability, adhesion ability, possible pathogen exclusion, and safety for intended hosts). These characteristics are reflected by the genes they have and the proteins they express. Among these, secreted and surface anchored proteins hold interesting roles in host-microbe interactions because these two are encountered first when the bacterial cells are introduced to its host. In this study, the secreted proteins of different lactobacilli strains will be studied via proteomics analysis, while the cell surface will be investigated via surface display technology. Specifically, the exoproteome of Lactobacillus mucosae LM1, Lactobacillus johnsonii PF01 and CI-10 will be collected and analyzed before and after introduction of bile acid - a stress factor that has crucial influence on the survival of bacteria in the gut. In addition, a surface display method, developed to use without genetic modifications on its lactobacilli host, will be used to compare six different lactobacilli strains. From the results of exoproteome analysis, it is found that the three strains differ at the species level before bile stress. However, similar adaptations were observed when addressing the stressful conditions. Metabolic adaptations that support the stress response of optimizing protein synthesis were found based on the significant changes in protein expression. Interestingly, LM1 secretes a lot of ribosomal proteins even during normal conditions. This hints to possible moonlighting functions of the said proteins when it comes to LM1 aggregation and adhesion abilities. The cell surface-based analysis of six lactobacilli strains reveal strain level specificity when it comes to anchoring of LysM – a well-used anchor domain for many other surface display studies. Notably, LM1 and Limosilactobacillus fermentum SK152 exhibited similar cell surface characteristics. However, based on CwBP-anchoring, SK152 might also have more choline binding sites on its cell wall and surface as compared to LM1, even though the domain originated from LM1. The results also suggest the unavailability of the binding sites for the other strains – PF01 and Lactiplantibacillus plantarum SK151, SK156, and SK157. Altogether, the results described the extracellular and cell surface proteins of different lactobacilli strains. These allowed us to understand the seven strains further, as requisite knowledge to their potential as probiotics.

Evaluation of Sulforaphene Induced Synergistic Enhancement of Carboplatin and Photodynamic Therapy Efficacy In Epithelial Cancer Cell Lines

Chatterjee, Saswata Graduate School, Dankook University 2017 국내박사