• 한국자기공명학회논문지
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• 제11권2호
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• pp.95-109
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• 2007

Vanadium-incorporated aluminophosphate microporous molecular sieve VH-SAPO-42 has been studied by electron spin resonance(ESR) and electron spin-echo modulation (ESEM) spectroscopies to determine the vanadium location and interaction with various adsorbate molecules. The results are interpreted in terms of V(IV) ion location and coordination geometry. Assynthesized VH-SAPO-42 contains only vanadyl species with distorted octahedral or trigonal bipyramidal coordination. Vanadium incorporated into H-SAPO-42 occupied extra-framework site. After calcinations in $O_2$ and exposure to moisture, only species A is observed with reduced intensities. Species A is identified as a $VO(H_2O)_2^{2+}$ complex coordinated to three framework oxygen atoms bonded to aluminum. When hydrated VH-SAPO-42 is dehydrated at elevated temperature by calcination, species A loses its water ligand and transforms to $VO^{2+}$ ions coordinated to three framework oxygens (species B). Species B reduces its intensities significantly after treatment with $O_2$ at high temperature, thus suggesting oxidation of $V^{4+}$ to $V^{5+}$. When dehydrated VH-SAPO-42 makes contact with $D_2O$ at room temperature, the ESR signal of species A is regained. The species is assumed as a $VO(O_f)_3(D_2O)_2$ by considering three framework oxygens. Adsorption of deuterated methanol on dehydrated VH-SAPO-42 results in another new vanadium species D, which is identified as a $VO(CD_3OH)_2$ complex. When deuterated ethylene is adsorbed on dehydrated VH-SAPO-42, another new vanadium species E identified as a $VO(C_2D_4)^{2+}$, is observed. Possible coordination geometries of these various complexes are discussed.

• 멤브레인
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• 제14권2호
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• pp.99-107
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• 2004

Carbon molecular sieve (CMS) membranes were prepared by pyrolysis of polyimides having carboxylic acid groups and applied to the hydrogen separation. The polymeric membranes having carboxylic acid groups showed different steric properties as compared with polymeric membranes having other side groups ($-CH_3$ and $-CF_3$) because of the hydrogen bond between the carboxylic acid groups. However, the microporous CMS membranes were significantly affected by the decomposable side groups evidenced from the wide angle X-rat diffraction, nitrogen adsorption isotherms, and single gas permeation measurement. Furthermore, the gas separation properties of the CMS membranes were essentially affected by the pyrolysis temperature. As a result, the CMS membranes Prepared by Pyrolysis of polyimide containing carboxylic acid froups at $700^{\circ}C$ showed the $H_2$ permeability of 3,809 Baller [$1{\times}10^{-10}$ H $\textrm{cm}^$(STP)cm/$\textrm{cm}^2$.s.cmHg], $H_2$/$N_2$, selectivity of 46 and $H_2$/$CH_4$ selectivity of 130 while the CMS membranes derived from polyimide showed the H$_2$ permeability of 3,272 Barrer, $H_2$/$N_2$ selectivity of 136 and $H_2$/$CH_4$ selectivity of 177.

• 대한바이러스학회지
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• 제30권1호
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• pp.61-70
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• 2000

Standard plaque assay using agarose-overlay has long been used for titration of many infectious virus particle. Plaque assay for the titration of varicella-zoster virus and its live vaccine requires three intermittent agarose overlay to visualize plaques. Overall procedure of the assay takes at least nine days from virus inoculation and microbe contamination including fungi is frequently accompanied during incubation period. We studied whether an immunofocus assay in conjunction with peroxidase-mediated immunohistochemical reaction may replace the standard plaque assay for the virus titration by comparing the two methods. A linear relationship was observed between number of foci and virus dilution. The number of foci in a given dilution of virus appeared a little higher than counted plaques formed in standard plaque assay. Independent titration results obtained from two assay methods for a given dilution of virus demonstrated a strong correlation ($r^2=0.99$). Foci of virus infected cells as revealed by the enzyme reaction could be counted either 4 days post-infection (p.i.) under low magnification (40X) microscopy, or 6 days p.i. by naked eye observation. Larger size of cell cuture plate, virus adsorption at $35^{\circ}C$, and 10% FBS in diluent appeared to be better conditions for the assay. Immunofocus assay will be an effective and dependable titration method for varicella-zoster virus and its live vaccine in place of the standard plaque assay in respect to accuracy, costs, and experimental convenience.

• 대한화학회지
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• 제37권10호
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• pp.867-873
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• 1993

결정화 시간 및 반응 혼합물내의 $H_2O/Al_2O_3$의 비가 AlPO$_4$-5 분자체의 합성에 미치는 영향을 X-선 회절(XRD), 질소흡착실험, 전자현미경(SEM) 그리고 고체상 $^{27}$Al nuclear magnetic resonance(NMR)를 사용하여 조사하였다. 반응온도가 150$^{\circ}$C일 때 AlPO$_4$-5의 결정화 시간에 따른 결정성은 S자형 곡선을 보였으며, 유도기간(induction period)은 1시간 이내인 것으로 나타났다. 반응물에서 생성물, AlPO$_4$-5로의 전환을 명확히 관측할 수 있었으며 약 2시간의 결정화 전후 측정된 모든 물성은 큰 변화를 보였다. 반응물내의 $H_2O/Al_2O_3$의 비가 증가함에 따라 다결정의 AlPO$_4$-5는 육각기둥 모양의 단결정으로 변화하였으며 얻어진 결정의 길이/너비의 비는 증가하였다.

• Bulletin of the Korean Chemical Society
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• 제28권5호
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• pp.783-790
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• 2007

The immobilization of proteins and their molecular interactions on various polymer-modified glass substrates [i.e. 3-aminopropyltriethoxysilane (APTS), 3-glycidoxypropyltrimethoxysilane (GPTS), poly (ethylene glycol) diacrylate (PEG-DA), chitosan (CHI), glutaraldehyde (GA), 3-(trichlorosilyl)propyl methacrylate (TPM), 3'-mercaptopropyltrimethoxysilane (MPTMS), glycidyl methacrylate (GMA) and poly-l-lysine (PL).] for potential applications in a nanoarray protein chip at the single-molecule level was evaluated using prismtype dual-color total internal reflection fluorescence microscopy (dual-color TIRFM). A dual-color TIRF microscope, which contained two individual laser beams and a single high-sensitivity camera, was used for the rapid and simultaneous dual-color detection of the interactions and colocalization of different proteins labeled with different fluorescent dyes such as Alexa Fluor® 488, Qdot® 525 and Alexa Fluor® 633. Most of the polymer-modified glass substrates showed good stability and a relative high signal-to-noise (S/N) ratio over a 40-day period after making the substrates. The GPTS/CHI/GA-modified glass substrate showed a 13.5-56.3% higher relative S/N ratio than the other substrates. 1% Top-Block in 10 mM phosphate buffered saline (pH 7.4) showed a 99.2% increase in the blocking effect of non-specific adsorption. These results show that dual-color TIRFM is a powerful methodology for detecting proteins at the single-molecule level with potential applications in nanoarray chips or nano-biosensors.

• Tribology and Lubricants
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• 제32권3호
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• pp.95-100
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• 2016

As an alternative fuel, biodiesel has excellent lubricating property. Previously, our research group reported that the properties of biodiesels depended on their composed molecular structure. In this study, we investigate lubricity and the mechanism of lubricity improvement of synthesized biodiesel molecules. We synthesize four types of biodiesel components from fatty acid via fisher esterification and soybean biodiesel from soybean oil via transesterification in high yield (92-96%). We analyze the lubricity of the five 5 types of biodiesel using HFRR (high frequency reciprocating rig). We estimate that the mechanism of lubricity is relevant to the molecular structure and structure conversion of biodiesel. The test results indicate that the longer the length of molecules and the higher the content of olefin, the better the lubricity of the biodiesel molecules. However, the wear scar size of the first test samples’ do not show a regular pattern with the wear scar size of the second test samples’. Moreover, we investigated the structure conversion of the biodiesels by using GC-MS for the recovered biodiesel samples from the HFRR test. However, we do not detect structure conversion. Thus, we conclude that the lubricity of biodiesel depends on how effectively solid adsorption and boundary lubrication occurs based on the size of the molecule and the content of olefin in the molecule. In addition, HFRR test condition in not sufficient for Diels-Alder cyclization of biodiesel components.

• 한국자기공명학회논문지
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• 제9권2호
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• pp.138-154
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• 2005

Vanadium-incorporated aluminophosphate molecular sieve $VO^{2+}-SAPO-5$ was studied by electron spin resonance (ESR) and electron spin echo modulation (ESEM) spectroscopies to determine the vanadium structure and interaction with various adsorbate molecules. It was found that the main species at low concentration of vanadium is a monomeric vanadium units in square pyramidal or distorted octahedral coordination, both in oxidation state (IV) for the calcined hydrated material and in oxidation state (V) for the calcined material. After calcinations in $O_2$ and exposure to moisture, only species A is observed with reduced intensities. It is suggested as a $VO(H_2O)_3^{2+}$ complex coordinated to two framework oxygen bonded aluminum. When calcined, hydrated $VO^{2+}-}SAPO-5$ is dehydrated at elevated temperature, a species loses its water ligands and transforms to $VO^{2+}$ ions coordinated to two framework oxygens (species B). Species B reduces its intensity, significantly after treatment with $O_2\;at\;600^{\circ}C$ for 5 h, thus suggesting oxidation of $V^{4+}\;to\;V^{5+}$. When dehydrated $VO^{2+}-SAPO-5$ contacts with $D_2O$ at room temperature, the EPR signal of species A is observed. Thus species assumed as a $VO^{2+}(O_f)_2(D_2O)_3$, by considering two framework oxygens. Adsorption of deuterated ethanol, propanol on dehydrated $VO^{2+}_{-}SAPO-5$ result in another new vanadium species E and F, respectively, which are identified as a $VO^{2+}-(CH_3CH_2OD)_3,\;VO^{2+}-(CH_3CH_2CH_2OD)_2$ complex. When deuterated benzene is adsorbed on dehydrated $VO^{2+}-SAPO-5$, another new vanadium species G, identified as a $VO^{2+}-(C_6D_6)$ is observed. Possible coordination geometries of these various complexes are discussed.

• 대한치과교정학회지
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• 제32권6호
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• pp.443-453
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• 2002

본 연구의 목적은 다양한 교정용 브라켓의 표면에 형성되는 타액성 피막의 조성을 확인하고, 전타액, 악하선타액 및 이 하선타액에서 유래하는 타액성 피막의 성분을 비교하는 것이다. 네 가지 서로 다른 종류의 교정용 브라켓을 본 연구에 사용하였다. 이들은 $022{\times}028$ Roth Prescription의 상악 소구치 브라켓으로 조성은 다음과 같다: 스테인레스 스틸, 단결정 사파이어, 다결정 알루미나 및 플라스틱 브라켓. 교정용 브라켓을 각각 전타액, 이하선타액 및 악하선타액에 2시간 배양하여 타액성 피막을 형성시켰다 브라켓 피막의 타액성분은 sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western transfer method 및 면역검출법을 통해 확인하였다. 이 결과 low-molecular weight salivary mucin, ${\alpha}-amylase$, secretory IgA (sIgA), acidic proline-rich proteins, cystatins 등이 모든 브라켓의 타액성 피막에 존재하였으며, 치아우식증의 원인균인 Streptococcus mutans의 부착을 촉진시키는 타액단백질인 high-molecular weight mucin은 어떤 브라켓에도 부착하지 않았다. 그러나, 비록 동일한 타액단백질이 모든 브라켓에서 발견되었지만, 타액단백질 부착 양상은 타액의 종류 및 브라켓의 종류에 따라 양적 및 질적으로 다르게 나타났다. 특히 sIgA는 이하선타액에서 유래한 브라켓 피막에 더 많이 부착하였고, cystatins의 경우는 플라스틱 브라켓에서 유래한 브라켓 피막에 더 많이 존재하였다 본 연구는 다양한 타액단백질이 교정용 브라켓에 부착하며, 타액단백질이 타액의 출처 및 브라켓의 종류에 따라 교정용 브라켓의 표면에 선택적으로 부착함을 나타내었다.

• 대한화학회지
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• 제49권1호
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• pp.29-34
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• 2005

• Bulletin of the Korean Chemical Society
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• 제34권6호
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• pp.1814-1822
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• 2013

By using density functional theory calculations, we have performed a systemic study on the electronic structures and topological properties of interactions between N-butylpyridinium nitrate ($[BPY]^+[NO_3]^-$) and thiophene (TS), benzothiophene (BT), dibenzothiophene (DBT), naphthalene (NAP). The most stable structure of $[BPY]^+[NO_3]^-$ ion pair indicates that hydrogen bonding interactions between oxygen atoms on $[NO_3]^-$ anion and C2-H2 on pyridinium ring play a dominating role in the formation of ion pair. The occurrence of hydrogen bonding, ${\pi}{\cdots}$H-C, and ${\pi}{\cdots}{\pi}$ interactions between $[BPY]^+[NO_3]^-$ and TS, BT, DBT, NAP has been corroborated at the molecular level. But hydrogen bonding and ${\pi}{\cdots}{\pi}$ interactions between $[BPY]^+[NO_3]^-$ and NAP are weak in terms of structural properties and NBO, AIM analyses. DBT is prior to adsorption on N-butylpyridinium nitrate ionic liquid.