• Bulletin of the Korean Chemical Society
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• 제35권4호
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• pp.1023-1028
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• 2014

Protonated caffeine ($CH^+$) and glucosamine ($GH^+$) overlapped in an analysis with ion mobility spectrometryquadrupole mass spectrometry. Ethyl lactate vapor (L) at different concentrations from 0 to 22 mmol $m^{-3}$ was added as a buffer gas modifier to separate these signals. The drift times of $CH^+$ and $GH^+$ increased with L concentration. The drift time increase was associated to clustering equilibria of $CH^+$ and $GH^+$ with one molecule of L and the equilibrium of $GH^+$ was more displaced to the formation of $GLH^+$ than that of $GLH^+$. $GH^+$ clustered more to L than $CH^+$ because $GLH^+$ formed more stable hydrogen bonds (26.30 kcal/mol) than $GLH^+$ (24.66 kcal/mol) and the positive charge in $GH^+$ was more sterically accessible than in $CH^+$. The aim of this work was to use theoretical calculations to guide the selection of a buffer gas modifier for IMS separations of two compounds that overlap in the mobility spectra and predict this separation, simplifying that empirical process.

• Advances in nano research
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• 제4권4호
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• pp.295-307
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• 2016

The present research work reports a low temperature ($40^{\circ}C$) chemical precipitation technique for synthesizing hydroxyapatite (HAp) nanoparticles of spherical morphology through a simple reaction of calcium nitrate tetrahydrate and di-ammonium hydrogen phosphate at pH 11. The crystallinity of the single-phase nanoparticles could be improved by calcinating at $600^{\circ}C$ in air. Thermogravimetric and differential thermal analysis (TG-DTA) revealed the synthesized HAp is stable up to $1200^{\circ}C$. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) studies confirmed the formation of spherical nanoparticles with average size of $23.15{\pm}2.56nm$ and Ca/P ratio of 1.70. Brunauer-Emmett-Teller (BET) isotherm of the nanoparticles revealed their porous structure with average pore size of about 24.47 nm and average surface area of $78.4m2g^{-1}$. Fourier transform infrared spectroscopy (FTIR) was used to confirm the formation of P-O, OH, C-O chemical bonds. Cytotoxicity and MTT assay on MG63 osteogenic cell lines revealed nontoxic bioactive nature of the synthesized HAp nanoparticles.

• 대한전자공학회논문지
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• 제26권3호
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• pp.130-136
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• 1989

보론이 도우핑된 수소화된 비정질 실리콘을 이용한 박막 트랜지스터를 플라즈마 CVD 방법으로 제작하여 트랜지스터의 특성 및 준안정성에 관한 연구를 수행하였다. 보론이 도우핑된 비정질 실리콘 ambipolar 트랜지스터를 열평형 온도 이상에서 급냉하면, active dopants가 증가하고 경계면 상태밀도가 감소하여 정공채널에 의한 드레인 전류가 증가하고 전자채널의 드레인 전류는 급냉 온도에 따라 증가하다 감소되는 현상을 측정하였다. 이런 급냉 효과는 실리콘내에 있는 수소의 운동과 밀접한 관계가 있고 active dopants, 댕글링 본드 및 경계면 상태밀도의 변화로 해석된다.

• 전기전자학회논문지
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• 제21권3호
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• pp.320-330
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• 2017

Porous nanosilica (PNS) has been identified as a potential candidate for controlled drug delivery. However, unmodified PNS-based carriers exhibited an initial release of loaded bioactive agents, which may limit their potential clinical applications. In this study, the surface of PNS was functionalized with adamantylamine (ADA) via disulfide bonds (-S-S-), PNS-S-S-ADA, which was then modified with cyclodextrin (CD)-heparin (Hep) (CD-Hep), PNS-S-S-CDH, for redox triggered rhodamine B (RhB) delivery. The obtained samples were then characterized by proton nuclear magnetic resonance ($^{1}H\;NMR$), Fourier transform infrared (FTIR), and transmission electron microscope (TEM). These results showed that PNS-S-S-CDH was successfully formed with spherical shape and average diameter of $45.64{\pm}2.33nm$. In addition, RhB was relatively encapsulated in the PNS-S-S-CDH (RhB@PNS-S-S-CDH) and slowly released up to 3 days. The release of RhB, in particular, was triggered due to the cleavage of -S-S- in the presence of dithiothreitol (DTT). It might be anticipated that the modified PNS can be used as redox-responsive drug delivery system in cancer therapy.

• 대한방사선기술학회지:방사선기술과학
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• 제43권4호
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• pp.273-280
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• 2020

In this study, the P contrast agent of Iopamidol, which is a nonionic iodide contrast agent most commonly used as a vascular contrast agent in medical institutions, and the O contrast agent of Ioversol, were studied. The physicochemical changes according to the temperature change were compared and analyzed using the Bruker Avance 500MHz Nuclear Magnetic Resonance Spectrometer owned by the Korea Basic Science Institute (KBSI). There was no physical or chemical change in the O contrast medium of Ioversol formulation in temperature change. However, in the P contrast agent of Iopamidol, a doublet peak began to appear in the 1.1 ppm region of the sample at 60℃, and the doublet peak was clearly observed in the sample at 80℃. As a result of this study, 1H-NMR analysis revealed that the P contrast agent of the Iopamidol formulation was dissociated from chemical bonds as it rose to a high temperature of 60℃ or higher, resulting in the formation of foreign substances. It was evaluated that the O contrast agent of Ioversol formulation had physico-chemical stability than the P contrast agent of Iopamidol formulation. As shown in this study, it is necessary to analyze the physical and chemical changes of contrast agents according to various environmental factors.

• Carbon letters
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• 제15권4호
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• pp.262-267
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• 2014

Pyrolized fuel oil (PFO) was reformed by novel electron beam (E-beam) radiation, and the elemental composition, chemical bonds, average molecular weight, solubility, softening point, yields, and density of the modified patches were characterized. These properties of modified pitch were dependent on the reforming method (heat or E-beam radiation treatment) and absorbed dose. Aromaticity ($F_a$), average molecular weight, solubility, softening point, and density increased in proportion to the absorbed dose of E-beam radiation, with the exception of the highest absorbed dose, due to modification by free radical polymerization and the powerful energy intensity of E-beam treatment. The H/C ratio and yield exhibited the opposite trend for the same reason. These results indicate that novel E-beam radiation reforming is suitable for the preparation of aromatic pitch with a high ${\beta}$-resin content.

• 한국표면공학회지
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• 제29권5호
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• pp.563-569
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• 1996

Degradation of $Zn_3N_2$ films is studied by using several analytical techniques. Polycrystalline $Zn_3N_2$ films prepared by reactie rf magnetron sputtering are kept in the air. Electrical and optical properties are measured by using van der Pauw technique and double-beam spectrometry. Structure and chemical bonding states are studied by X-ray diffraction(XRD), Fourier transfer infrared ray spectroscopy(FT-IR) and X-ray photoelectron specroscopy (XPS). Significant differences are observed in optical properties between the degraded film and the ZnO film. XRD analysis reveals that the degraded film contains very small ZnO grains because very weak and broad ZnO peaks are observed. XPS and FT-IR measurements reveal the formation of $Zn(OH)_2$ in the degraded film. The existence of N-H bonds in degraded films is exhibited from the N 1s spectra. $Zn_3N_2$ change into the mixture of ZnO, $Zn(OH)_2$ and an ammonium salt.

• 한국염색가공학회지
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• 제29권2호
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• pp.69-76
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• 2017

To get the proper treatment conditions, sulfonation reactions of persimmon tannin with sodium sulfite and sulfuric acid were proceeded in various settings, respectively. Also, the property changes were investigated by carrying out the additional analysis: elementary analysis and instrumental analysis using FT-IR, DSC, and TGA. The degree of $-SO_3Na$ substitutions appeared 0.216 and 0.208 under the treatment time of 3 hours and 6 hours, respectively and the degree of $-SO_3H$ substitutions indicated 0.200 and 0.167 under 9 hours and 18 hours, respectively by elemental analysis. In terms of the FT-IR spectras, there was a peak based on the bonds of pyran ring and ether in relation to non-treated and sulphonated tannin at $1,102cm^{-1}$. No peak was shown in the sulfited tannin. An absorption peak which was due to the $C{\rightarrow}O$ of secondary -OH group became evident in nontreated and sulfited tannin at $1,092cm^{-1}$ and $1,090cm^{-1}$, respectively but the same result was not found in sulphonated tannin. The results of TGA analysis of the sulfonated persimmon tannin showed that the sulfonation of it improved thermal properties.

• 한국식품조리과학회지
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• 제10권1호
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• pp.76-79
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• 1994

본 연구는 청포묵의 제조과정에서 일어나는 동부전분의 형태변화와 결정성의 변화를 조사하기 위하여 수행하였다. 동부전분은 70~75$^{\circ}C$에서 결정성이 상실되는 것을 편광현미경과 X-선 회절도로부터 알 수 있었다. 가열에 따른 동부전분의 변화를 SEM관찰했을 때, 65~75$^{\circ}C$에서는 팽윤이 일어나면서도 입자의 형태는 보전되었으나 85$^{\circ}C$ 이상에서는 용출물이 많이 빠져나온 후 입자의 중첩이 일어나는 것을 볼 수 있었다. 묵의 형성, 즉 호화전분의 겔화는 한 그룹의 약한 수소결합에 의하여 안정화되는 junction zone이 형성되어 망상조직이 이루어지는 것임이 저장했던 전분겔을 재가열할 때의 DSC thermogram을 통하여 나타났고, 재가열한 전분의 X-선 회절도 분석한 결과 결정화는 아닌 것이 밝혀졌다.

• 대한화학회지
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• 제63권1호
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• pp.29-36
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• 2019

A potentially tetradentate Schiff base ligand, 2-((2-((pyridin-2-ylmethylene)amino)ethyl)amino)ethan-1-ol (PMAE), and its cadmium(II) complex, [$Cd(PMAE)I_2$] (1), were prepared and characterized by elemental analysis, FT-IR, Raman, $^1H$ and $^{13}C$ NMR spectroscopies and single-crystal X-ray diffraction. In the crystal structure of 1, the cadmium atom has a slightly distorted square-pyramidal geometry and a $CdN_3I_2$ environment in which the PMAE acts as an $N_3$-donor. In the crystal packing of the complex, the alcohol and amine groups of the coordinated ligands participate in hydrogen bonding with iodide ions and form $R^2{_2}(14)$ and $R^2{_2}(8)$ hydrogen bond motifs, respectively. In addition to the hydrogen bonds, the crystal network is stabilized by ${\pi}-{\pi}$ stacking interactions between pyridine rings. The thermodynamic stability of the isolated ligand and its cadmium complex along with their charge distribution patterns were studied by DFT and NBO analysis.