• 공업화학
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• 제29권4호
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• pp.395-398
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• 2018

전기장 하에서 유기물은 전기장에 의해 부여된 여러 가지 힘의 영향을 받아서 특이한 거동을 나타낸다. 본 연구에서는, 지금까지 개별적으로 고찰되어 왔던 전기장 하에서의 블록 공중합체와 고분자 블렌드의 미세 거동을 비교 분석하여 특징적인 차이점을 알아보고자 한다. 두 가지 고분자가 공유결합으로 연결된 블록 공중합체와 약한 상호작용으로 혼합된 고분자 블렌드 시스템을 비교대상으로 하였다. 이때, 구성 고분자로는 비슷한 유전상수를 갖는 폴리아크릴로 나이트릴과 폴리메틸메타아크릴레이트를 도입하였다. 유사한 분자량, 같은 농도, 같은 전기장 세기하에서 고분자 블렌드가 전기장에 더욱 민감하게 반응하는 것을 알 수 있었다. 이는 공유결합이 분자의 운동성을 제약하여 전기장에 덜 민감하게 반응하도록 거동하기 때문이다. 본 연구는 고분자 물질의 전기장 하에서의 거동을 이해하는 중요한 정보를 제공할 것이다.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1998년도 Proceedings of UNESCO-internetwork Cooperative Regional Seminar and Workshop on Bioassay Guided Isolation of Bioactive Substances from Natural Products and Microbial Products
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• pp.150-151
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• 1998

Drug delivery to the brain is facilitated by the synthesis of chimeric peptides, where in neuropharmaceuticals are linked to a vector such as an antibody to the transferrin receptor that mediates transcytosis through the blood-brain barrier (BBB). When disulfide linkers are used in the chimeric peptide, it is crucial that the S-S bridge is stable during transit and that cleavage does not occur prematurely within endothelial cells, as the peptide drug moiety would then be sequestered by the BBB instead of passing through it. The present study addressed that problem. As a model drug a metabolically stable opioid peptide, [$^3$H]DALDA (Tyr-dArg-Phe-Lys-NH$_2$), was used. It was monobiotinylated with NHS-SS-biotin to yield bio-[$^3$H]DALDA. The biotinylated peptide was bound to the vector OX26-SA which is a covalent conjugate of OX26 and streptavidin (molar ratio = 1: 1). In vitro treatment of the chimeric peptide, bio-[$^3$H]DALDA/OX26-SA, with a reducing agent, dithiothreitol, released the labeled peptide from the vector by conversion of bio-[$^3$H]DALDA to the desbiotinylated derivative, desbio-[$^3$H]DALDA.

• 한국재료학회지
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• 제12권4호
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• pp.274-278
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• 2002

Discrete-variational(DV)-$X{\alpha}$ method was applied to investigate the electronic structures of spinel- type manganese oxide which is well known to the high performance adsorbent or cathode material for lithium ion. The results of DOS(density of states) and Mulliken population analysis showed that Li was nearly fully ionized and interactions between Mn and O were strong covalent bond. The effective charge of Li and Mn was +0.77 and +1.44 respectively and the overlap population between Mn and O was 0.252 in $LiMn_2O_4$. These results from DV-X$\alpha$ method were well coincided with the experimental result by XPS analysis and supported the feasibility of theoretical interpretation for the $LiMn_2O_4$ compound.

• Fibers and Polymers
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• 제7권2호
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• pp.174-179
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• 2006

Dyeing and color fastness properties of a reactive disperse dye containing an acetoxyethylsulphone group on PET, Nylon, silk and N/P fabrics were examined. The reactive disperse dye exhibited almost the same dyeing properties on PET fabric as a conventional disperse dye except the level of dye uptake. The most appropriate pH and dyeing temperature for the dyeing of Nylon fabric were 7 and $100^{\circ}C$ respectively. The build-up on Nylon fabric was good and various color fastnesses were good to excellent due to the formation of the covalent bond. Application of the reactive disperse dye on silk fabric at pH 9 and $80^{\circ}C$ yielded optimum color strength. The rate of dyeing on Nylon fabric was faster than that on PET fabric when both fabrics were dyed simultaneously in a dye bath, accordingly color strength of the dyed Nylon was higher. The reactive disperse dye can be applied for one-step and one-bath dyeing of N/P mixture fabric with good color fastness.

• International Journal of Control, Automation, and Systems
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• 제4권3호
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• pp.382-393
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• 2006

Mechanical system dynamics plays an important role in the area of computational structural biology. Elastic network models (ENMs) for macromolecules (e.g., polymers, proteins, and nucleic acids such as DNA and RNA) have been developed to understand the relationship between their structure and biological function. For example. a protein, which is basically a folded polypeptide chain, can be simply modeled as a mass-spring system from the mechanical viewpoint. Since the conformational flexibility of a protein is dominantly subject to its chemical bond interactions (e.g., covalent bonds, salt bridges, and hydrogen bonds), these constraints can be modeled as linear spring connections between spatially proximal representatives in a variety of coarse-grained ENMs. Coarse-graining approaches enable one to simulate harmonic and anharmonic motions of large macromolecules in a PC, while all-atom based molecular dynamics (MD) simulation has been conventionally performed with an aid of supercomputer. A harmonic analysis of a macroscopic mechanical system, called normal mode analysis, has been adopted to analyze thermal fluctuations of a microscopic biological system around its equilibrium state. Furthermore, a structure-based system optimization, called elastic network interpolation, has been developed to predict nonlinear transition (or folding) pathways between two different functional states of a same macromolecule. The good agreement of simulation and experiment allows the employment of coarse-grained ENMs as a versatile tool for the study of macromolecular dynamics.

• 대한방사성의약품학회지
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• 제2권1호
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• pp.9-16
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• 2016

Carbon-11 is one of the most sensitive and desirable positron emission tomography radio-isotope, which offers the capacity to be incorporated, through a covalent bond, into biologically active molecules without altering their biological properties. Carbon-11 can be obtained from the cyclotron with two different chemical forms: $[^{11}C]CO_2$ and $[^{11}C]CH_4$. [$^{11}C$]Methyl iodide has been widely used as a highly reactive labelling precursor that can be applied to label carbon-11 with biologically active molecules via alkylation of N-, O-, or S-nucleophiles. A more recent and still challenging labeling method is transition metal mediated $^{11}C$-carbonylation. Advances in organic chemistry, radiochemistry and improved automated techniques greatly encourage researchers to develop more carbon-11 labelled radiotracers for molecular imaging studies. This mini-review will introduce a historical track of carbon-11 chemistry combining with examples and its role in near future.

• 한국염색가공학회지
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• 제33권2호
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• pp.64-71
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• 2021

Large amount of formaldehyde could be released inevitably during the flame-retardant (FR) treatments or from the finished fabrics using Provatex reagent and Proban polymers which have been used as durable FRs for cotton. A water-soluble cyclophosphazene derivative was synthesized as an ecofriendly phosphorus-based FR for cotton fibers. Dichloro tetrakis{N-[3-(Dimethylamino)propyl]methacrylamido} cyclcophosphazene (DCTDCP) was synthesized through the substiutution reaction of Hexachloro cyclophosphazene and N-[3-(Dimethylamino)propyl] methacrylamide at a mole ratio of 1 : 4, which can be cured dually by both alkaline treatment and UV irradiation. More crosslinked networks were produced through the addition of Triacryloyl hexahydrotriazine and Acrylamide as a UV-curable crosslinker and a comonomer respectively. Both flame retardancy and washing durability of the FR cotton were improved synergistically. The durability improvement may be caused by the covalent bond formation of the FR with cellulose and the high degree of polymerization of DCTDCP, which can be verified by the pyrolysis and combustion behaviors analyzed by LOI, TGA, and microcalorimeter.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.255-256
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• 2023

The development of corrosion inhibitors with outstanding performance is a never-ending and complex process engaged in by researchers, engineers and practitioners. Computational assessment of organic corrosion inhibitors performance is a crucial step towards the design of new task-pecific materials. Herein, electronic features, adsorption characteristics and bonding mechanisms of two pyridine oximes, namely 2-pyridylaldoxime (2POH) and 3-pyridylaldoxime (3POH) with the iron surface were investigated using molecular dynamics (MD), and self-consistent-charge density-unctional tight-binding (SCC-DFTB) simulations. SCC-DFTB simulations revealed that 3POH molecule can form covalent bonds with iron atoms in its neutral and protonated states, while 2POH molecule can only bond with iron through its protonated form, resulting in interaction energies of -2.534, -2.007, -1.897, and -0.007 eV for 3POH, 3POH+, 2POH+, and 2POH, respectively. Projected density of states (PDOSs) analysis of pyridines-Fe(110) interactions indicated that pyridine molecules chemically adsorbed on the iron surface.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 International Symposium
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• pp.111-124
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• 2003

기존의 오염물질을 제거하는 많은 화학적-물리적 정화 방법은 고비용과 오랜 시간을 요구하는 처리 과정 등의 단점을 갖고 있는 경우가 많았다. 따라서 흙과 수(水)환경내로 유입된 오염물질을 빠른 시간 내에 제거 할 수 있는 대안이 요구 되었다. 흙에 유출된 화합 물질 중 상당양은 흙에 의해 격리, 구속되고 이로 인해 일단 구속된 오염물질은 물과 유기 용매에 의해서도 잘 추출되지 않는 것으로 보고 되고 있다. 이러한 흙에 의한 오염물질의 비유동성(immobilization) 과정은 오염물질의 제거 기술의 대안으로 평가 될 수 있다. 기존 연구자들의 연구 결과, 화학적 혹은 물리적 반응 작용을 통해 오염물질을 흙을 구성하는 물질에 구속할 수 있음이 증명되었다. 이러한 과정 중 환경적 측면에서 볼 때, 화학적 반응이 더 우수하다 할 수 있다. 이는 강한 공유결합(covalent bonds)으로 연결될 경우 미생물의 활동이나 화학 처리로도 이를 분리하기 어렵기 때문이다. 리그닌(lignin) 분해에서 발생하는 휴믹(humic) 물질 등이 안정 된 화학적 연결을 통해 흙 매질 내에 오염물질과 결합하는 대표적 물질이다. 인위적으로 제조된 많은 화학물질은 자연적에서 발생하는 휴민산 발생원(humic acid precursors)과 닮았다. 따라서 화학물은 부식 과정(humifications process)동안 부식토(humus) 내로 병합(incorporate)되어 진다. 일단 이렇게 구성된 결합체는 생물체와 오염물질과의 반응을 방지하여 오염물질로 인한 생물체로의 독성을 감소시키는 역할을 하게 된다. 본 논문에서는 이러한 흙의 유기물(organic matter)와 오염물질과의 결합체에 대한 평가로서 다음의 항목에 대한 고찰이 이루어져야 함을 강조하였다. (a)결합체에서 생물체(biota)와의 반응에 의해 오염물질은 감소되는가\ulcorner (b) 모(parent) 화합물과 비교하여 복합체 생성물(complexed products)이 얼마나 덜 유독한가\ulcorner 그리고 (c)지하수 오염이 오염물질의 유동성 구속에 의해 얼마나 감소되는지\ulcorner

• 대한화학회지
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• 제56권6호
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• pp.679-691
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• 2012

New series of metal complexes of Co(II), Ni(II), Cu(II), Zn(II), Pd(II) and Pt(II) with 4-(p-chlorophenyl)-1-(pyridin-2-yl)thiosemicarbazide (HCPTS) have been synthesized and characterized by elemental analyses, magnetic moment, spectra (IR, UV-Vis, $^1H$ NMR, mass and ESR) and thermal studies. The IR data suggest different coordination modes for HCPTS which behaves as a monobasic bidentate with all metal ions except Cu(II) and Zn(II) which acts as a monobasic tridentate. Based on the electronic and magnetic studies, Co(II), Cu(II), Pd(II) and Pt(II) complexes have square - planner, Ni(II) has mixed stereochemistry (tetrahedral + square planar), while Zn(II) is tetrahedral. Molar conductance in DMF solution indicates the non-ionic nature of the complexes. The ESR spectra of solid copper(II) complex show $g_{\parallel}$ (2.2221) > $g_{\perp}$ (2.0899) > 2.0023 indicating square-planar structure and the presence of the unpaired electron in the $d_x2_{-y}2$ orbital with significant covalent bond character. The thermal stability and degradation kinetics of the ligand and its metal complexes were studied by TGA and DTA and the kinetic parameters were calculated using Coats-Redfern and Horowitz-Metzger methods. The complexes have more antibacterial activity against some bacteria than the free ligand. However, the ligand has high anticancer activities against HCT116 (human colon carcinoma cell line) and HEPG2 (human liver hepatocellular carcinoma cell line) compared with its complexes.