• Bulletin of the Korean Chemical Society
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• 제28권10호
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• pp.1725-1728
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• 2007

Mast cells are key effector cells in the early phase allergic inflammation and in diverse immunological and pathological processes. In order to understand the effect on reduction of the anti-dinitrophenyl (DNP) IgE antibody-induced β-hexosaminidase release in RBL-2H3 rat mast cells, a novel series of 4-senecioyloxymethyl- 6,7-dimethoxycoumarins (SMDC) was prepared by reacting 4-chloromethyl-6,7-dimethoxycoumarin with various carboxylic acids. Compounds 8-11 with cyclic moiety such as phenyl, thiophenyl, pyridinyl, and furanyl group were found to inhibit-hexosaminidase release more potently (5.98-9.62 μM) than compounds 3- 7 and 12 with acyclic moiety (19.32-76.78 μM). Furthermore, compounds 8 and 9 inhibited IgE-induced ear swelling and significantly reduced systemic passive cutaneous anaphylaxis reaction in mice.

• KSBB Journal
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• 제23권5호
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• pp.408-412
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• 2008

본 연구에서는 당뇨병치료제인 로시글리타존약물를 생분해성 PLGA 나노입자에 봉입시킴으로서 위장흡수율과 물에 대한 용해도를 증가시키기 위한 나노제제 개발에 기반을 두고 있다. 특히 제조조건에 따라 형태 및 크기가 조절가능한 나노입자를 제조하고자 하였고, 실험결과 Emulsion-evaporation방법을 사용하여 100-150 nm 크기의 고른 입자분포를 가진 나노입자를 제조하였다. 다양한 농도의 약물 존재하에서 나노입자를 제조함으로서 1%까지의 약물이 80% 이상의 봉입율로 제조될 수 있음을 확인하였다. 또한 나노입자의 크기는 PVA양을 조절하면서 크기분포를 제어하였다. 36시간 동안의 용출실험 결과 초기 약간의 Burst effect가 있었으나 36시간동안 일정하게 약물이 용출되어 나옴을 확인하였다. 앞으로의 연구를 통해, 고효율의 경구제제용 당뇨병치료제 운반체 개발에 중점을 둘 예정이다.

• 한국염색가공학회:학술대회논문집
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• 한국염색가공학회 2011년도 제44차 학술발표회
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• pp.98-98
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• 2011

직물의 경우 드레이프성을 줄이고 KOSHI감(stiffness)을 부여하기 위해 일반적으로 나이프(knife) 코팅가공을 주로 사용한다. 하지만 니트는 워낙 신축성이 뛰어나기 때문에 큰 장력을 요구하는 일반 코팅공정을 적용할 경우 원단이 나이프에 밀리는 현상과 신장 상태에서 경화되어 니트 특유의 신축성을 완전히 읽어버리는 문제가 발생한다. 따라서 니트 코팅 가공을 위해 원단에 장력이 걸리지 않으며 니트 원단에 직접 수지를 도포하는 방식이 아닌 간접 도포가 가능한 장비를 고안하였다. 즉, 아래에 나타낸 모식도와 같이 프로팅이나 over roll 나이프 방식을 사용하여 전사에 필요한 수지를 R/F에 코팅하고 이를 니트와 붙인 후 열풍 건조기와 열실린더를 통과시켜 수지가 니트에 전사되도록 하는 것이다. 본 연구에서는 고신축성과 탁월한 포면 터치감을 가지는 니트를 겉옷 및 다양한 용도로 전개하기 위해 R/F(releas fabric)의 조건을 설정 및 코팅 조건 설정을 통해 니트 가공 직물의 성능 변화를 살펴보기로 한다.

• Journal of Advanced Marine Engineering and Technology
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• 제18권1호
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• pp.81-91
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• 1994

Combustion noise involved with chemical heat release and turbulent process in turbopropulsion systems, gasturbine, industrial furnaces and internal engines is indeed noisy. The experimental study reported in this paper is made to identify a dominant combustion noise in jet flames. Gaseous propane and kerosene fuel have been used with air as the oxidizer in a different jet combustion systems. Combustion and aerodynamic noise are studied through far field sound pressure measurements in an anechoic chamber. And also mean temperature and velocities and turbulent intensities of both isothermal and reacting flow fields were measured. It is shown that axial mean velocity of reacting flow fields is higher about 1 to 3m/sec than that of cold flow in a gaseous combustor. As the gaseous fuel flow rate increases, the acoustic power increases. But the sound pressure level for the spray flame decreases with increasing equivalence ratio. The influence of temperature in the combustion fields due to chemical heat release has been observed to be a dominant noise source in the spray flame. The spectra of combustion noise in gaseous propane and kerosene jet flame show a predominantly low frequency and a broadband nature as compared with the noise characteristics in an isothermal air jet.

• Bulletin of the Korean Chemical Society
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• 제31권9호
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• pp.2542-2546
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• 2010

The objective of this paper was to investigate the effect of dextran gel on preparation of nano-liposomes loaded with ginkgolide. During preparation, Sephadex G75, G50 and G25 were added in the aqueous phase respectively. From the experiment, nano-liposomes prepared by dextran gels were found spherical and smooth. The result indicated that aperture of dextran gels were narrower, particle size of nano-liposomes was smaller (207.13 ~ 89.16 nm) and zeta potential was greater (-36.2 ~ -29.5 mV) in more negative. The study also revealed that differences of the entrapment efficiency and drug loading among the three types of nano-liposomes were not significant. In vitro drug release test demonstrated that nano-liposomes had a better controlled release. To conclude, by using dextran gel in the preparation of nano-liposome loaded with ginkgolide, the particle size could be effectively controlled and the drug stability could be improved.

• KSBB Journal
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• 제22권3호
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• pp.146-150
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• 2007

Poly (3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] 미립구를 용매증발법으로 제조하였다. 3.9 mol% 4HB 조성의 P(3HB-co-4HB)를 Ralstonia eutropha의 유가식 배양으로부터 합성하였다. 계면활성제의 농도 및 종류(Tween 80, sodium dodecylsulfate, polyvinyl alcohol), 분산안정제 (Acacia)의 첨가, 고분자 및 모델 약물 (bovine serum albumin)의 농도 등이 미립구 입자 크기에 미치는 효과 및 in vitro 약물 방출 특성을 조사하였다. 평균 입자크기는 분산 안정제 첨가시 감소하였으며, 계면활성제, 약물 및 고분자의 농도가 증가할수록 증가하였다. 약물 방출량은 입자 크기가 감소할수록 증가하였다.

• Macromolecular Research
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• 제15권7호
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• pp.646-655
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• 2007

To achieve targeted drug delivery for chemotherapy, a ligand-mediated nanoparticulate drug carrier was designed, which could identity a specific receptor on the surfaces of tumor cells. Biodegradable poly(ethylene oxide)/poly$({\varepsilon}-caprolactone)$ (PEG/PCL) amphiphilic block copolymers coupled to biotin ligands were synthesized with a variety of PEG/PCL compositions. Block copolymeric nanoparticles harboring the anticancer drug paclitaxel were prepared via micelle formation in aqueous solution. The size of the biotin-conjugated PEG/PCL nanoparticles was determined by light scattering measurements to be 88-118 nm, depending on the molecular weight of the block copolymer, and remained less than 120 nm even after paclitaxel loading. From an in vitro release study, biotin-conjugated PEG/PCL nanoparticles containing paclitaxel evidenced sustained release profiles of the drug with no initial burst effect. The biotin-conjugated PEG/PCL block copolymer itself evidenced no significant adverse effects on cell viability at $0.005-1.0{\mu}g/mL$ of nanoparticle suspension regardless of cell type (normal human fibroblasts and HeLa cells). However, biotin-conjugated PEG/PCL harboring paclitaxel evidenced a much higher cytotoxicity for cancer cells than was observed in the PEG/PCL nanoparticles without the biotin group. These results showed that the biotin-conjugated nanoparticles could improve the selective delivery of paclitaxel into cancer cells via interactions with over-expressed biotin receptors on the surfaces of cancer cells.

• 대한화학회지
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• 제58권1호
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• pp.92-99
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• 2014

The pH sensitive hydrogels composed of N-isopropylacrylamide (NIPA) and acryloyl phenylalanine (APA) were prepared by redox polymerization using N,N'-methylenebisacrylamide (MBA) as a crosslinker. Anti-inflammatory and analgesic agent, Keterolac Tromethamine (KT), was loaded successfully into poly(NIPA-co-APA) copolymeric hydrogels by swelling equilibrium method. To understand the nature of drug in the polymeric matrix, the newly synthesized drug loaded poly(NIPA-co-APA) copolymeric hydrogels were characterized by using differential scanning calorimetry (DSC) and X-ray diffraction (XRD) techniques. The scanning electron microscopy (SEM) technique result indicates the spherical smooth surface of the hydrogels. The drug (KT) releasing nature of the poly(NIPA-co-APA) hydrogels was studied in pH 1.2 and 7.4. Effects of drug loading, crosslinking agent, pH and the ionic strength of the external medium on swelling of hydrogels were also investigated.

• Bulletin of the Korean Chemical Society
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• 제23권6호
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• pp.872-879
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• 2002

One of the improtant characteristics of core-shell type nanoparticles is the long-term storage and reuse as an aqueous injection solution when required. For this reason, reconstruction of lyophilized core-shell type nanoparticles is considered to be essential . BAB type triblock copolymers differ from AB type diblock copolymers, which contain the A block as a hydrophilic part and the B block as a hydrophobic part. by not being easily redistributed into phosphate-buffered saline (PBS, pH 7.4, 0.1 M). Therefore, lyophilized core-shell type nanoparticles of CEC triblock copolymer were reconstituted using a somication process with a bar-type sonicator in combination with a freezing-thawing process. Soncation for 30s only resuspended CEC nanoparticles in PBS; their particle size distribution showed a monomodal pattern with narrow size distribution. The bimodal size distribution pattern and the aggregates were reduced by further sonication for 120 s but these nanoparticles showed a wide size distribution. The initial burst of drug release was increased by reconstitution process. The reconstitution of CEC core-shell type nanoparticles by freezing-thawing resulted in trimodal distribution pattern and formed aggregates, although freezing-thawing process was easier than sonication . Drug release form CEC nanoparticles prepared by freezing-thawing was slower than from the original dialysis solution. Although core-shell typenanoparticles of CEC triblock copolymers were not easily performed. Cytotoxicity testing of core-shell type nanoparticles of CEC-2 triblock copolymers containing clonazepam (CNZ) was performed using L929 cells. Cytotoxicity of CNZ was decreased by incorporation into nanoparticles.

• Environmental Engineering Research
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• 제25권3호
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• pp.274-280
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• 2020

The marine sediment sustains from the anoxic condition due to increased nutrients of external sources. The nutrients are liberated from the sediment, which acts as an internal source. In hypoxic environments, anaerobic respiration results in the formation of several reduced matters, such as N₂ and NH₄⁺, N₂O, Fe²⁺, H₂S, etc. The experimental results have shown that nitrogen and sulfur played an influential, notable role in this biogeochemical cycle with expected chemical reductions and a 'diffusive' release of present nutrient components trapped in pore water inside sediment toward the bulk water. Nitate/ammonium, sulfate/sulfides, and ferrous/ferric irons are found to be the key players in these sediment-waters mutual interactions. Organonitrogen and nitrate in the sediment were likely to be converted to a form of ammonium. Reductive nitrogen is called dissimilatory nitrate reduction to ammonium and denitrification. The steady accumulation in the sediment and surplus increases in the overlying waters of ammonium strongly support this hypothesis as well as a diffusive action of the involved chemical species. Sulfate would serve as an essential electron acceptor so as to form acid volatile sulfides in present of Fe³⁺, which ended up as the Fe²⁺ positively with an aid of the residential microbial community.