• 한국토양비료학회지
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• 제32권4호
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• pp.421-428
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• 1999

토양내에서 흑운모의 풍화에 의하여 방출된 칼륨이 식물 성장에 필요에 의한 중요한 영양분의 원천의 하나로 인식되어왔다. 온난기후하에서 흑운모 화강암으로부터 발달된 토양-saprolite내에서 sand 크기의 흑운모의 풍화에 대하여 편광 현미경, 전자 현미경, X-선 회절 및 electron microprobe를 이용하여 형태학적, 광물학적, 그리고 화학적인 변화를 관찰하였다. 흑운모는 풍화가 진행될수록 그 색이 흑색에서 담황색으로 변했으며, paleochroism을 점점 잃어갔으며 그리고 가장자리와 층간 모두에서 풍화가 관찰되었다. 육각형의 구멍이 풍화된 흑운모 표면에서 관찰되었으며 그 수는 풍화가 더많이 진행된 흑운모에서 더 많은 경향을 보여주었다. 흑운모는 hydrobiotite, degraded biotite, illite 같은 중간단계 광물을 거치거나 혹은 중간과정이 없이 풍화에 의하여 kaolinite로 변형되었다. 풍화된 흑운모의 화학 성분은 표층으로 올라오면서 kaolinite의 화학 성분에 근접하는 경향을 보여주었으며 Si와 Al농도는 증가하였으며 K, Fe, Mg, Mn, Ti 함량은 감소하였다.

• 대한화학회지
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• 제42권4호
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• pp.411-415
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• 1998

인체 피부흑색종 세포에 대한 epigallocatechin gallate의 세포독성작용을 평가하고, 광학현미경적 관찰을 실시하여 인체 피부흑색종 세포의 형태학적인 변화를 볼 수 있었다. 세포독성은 비색정량분석법, NR정량분석법과 SRB정량분석법으로 측정하였다. 이런 결과는 epigallocatechin gallate에 항암활성을 보여준다.

• 대한화장품학회지
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• 제34권4호
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• pp.311-316
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• 2008

본 연구에서는 모발의 내부 및 외부구조에 자외선이 미치는 영향에 관하여 조사를 수행하였다. 자외선이 조사된 모발의 형태학적 및 화학적 구조의 변화를 알아보기 위해 주사전자현미경(SEM), 투과전자현미경(TEM), 공초점레이져주사현미경(CLSM) 등을 사용하였다. SEM상에서 자외선이 조사된 모발은 자외선에 의한 화학적 산화반응에 의한 표면이 거칠고 부풀어진 형태를 보였다. 이황화결합(disulfide bond)의 산화에 의한 시스테인산(cysteic acid)의 분해로 팽윤부위가 관찰되었다. 또한 자외선 조사에 의해 표면색의 변화를 나타내었다. TEM 분석결과 버진헤어(virgin hair)의 경우에는 매끄러운 표면구조를 나타내었지만, 자외선 조사모발에 있어서는 거칠고 모수질층이 갈라진 형태를 보여주었다. 모피질층에 존재하는 멜라닌 입자의 크기가 감소하고 소실되는 것이 관찰 되었다. CLSM에 의해 3차원적 구조의 입체영상을 얻을 수 있었으며, 광학분할에 의한 버진헤어는 강한 형광을 나타내었지만, 자외선 조사모발은 낮은 형광을 보여주었다. 이는 버진헤어의 경우 자동형광을 나타낼 수 있는 방향족 아미노산이 많이 존재하는데 비해 자외선 조사모발은 방향족 아미노산이 파괴되어 낮게 나온 것으로 여겨진다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.159-159
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• 2009

In this work, nitrogen and oxygen functionalities was introduced to the graphite nanofibers (GNFs) and their effect on electrocatalytic performance of the GNF supports for direct methanol fuel cells (DMFCs) was invesigated. The nitrogen and oxygen groups were introduced through the urea treatments and acid treatment, respectively. And, PtRu catalysts deposited on modified GNFs were prepared by a chemical reduction method. The catalysts were characterized by means of elemental analysis, nitrogen adsorption, and X-ray photoelectron spetroscopy (XPS). The structure and morphological characteristics of the catalysts were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). As a result, the Pt-Ru nanoparticles were impregnated on GNFs with good formation in 3-5 nm. And, the cyclic voltammograms for methanol oxidation revealed that the methanol oxidation peak varied depending on changes of surface functional groups. It was thus considered that the PtRu deposition was related to the reduction of PtRu and surface characteristics of the carbon supports. The changes of surface functional groups were related to PtRu reduction, significantly affect the methanol oxidation activity of anode electrocatalysts in DMFCs.

• 패션비즈니스
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• 제12권6호
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• pp.23-33
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• 2008

The physico-chemical characteristics by bleaching treatments were assessed by several instrumental analyses such as surface morphology, chemical structural change, color change as well as tensile strength. The change of morphological characteristic was observed through scanning electron microscope(SEM). The observation of the fine structure on hair surface by SEM showed the bleached hair had much damaged to hair cuticle, and some of cuticle surface were worn away. To investigate the chemical structural changes in hair keratin, the cross-sections of hair samples were directly analysed using Fourier transform infrared microspectroscopy(FT-IRM). The results showed the cysteic acid S=O band intensity was distinctively increased by performing the bleaching treatment. The cleavage of cystine was appeared to proceed primarily through the sulfur-sulfur (-S-S-) fission whereby cysteic acid was formed as a principal oxidation products. The distribution of amide I band in hair keratin was determined by attenuated total reflectance(ATR) FT-IR mapping image. The results showed that the outer side of hair cortex was more damaged than the inner side of the hair cortex. Also, during chemical bleaching of the hair with alkaline peroxide, the hair was turned to reddish yellow due to the oxidative degradation of eumelanin. This means the eumelanin is more unstable than pheomelanin in chemical oxidation. With bleaching, the tensile strength was also reduced as a results of the chemical oxidation.

• Bulletin of the Korean Chemical Society
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• 제14권1호
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• pp.43-47
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• 1993

Poly(2-cyano-5-methoxy-1,4-phenylenevinylene), PCMPV and a series of PPV copolymers containing 2-cyano-5-methoxy-1,4-phenylenevinylene (CMPV) units were prepared via the water-soluble precursor method. They were obtained in films form and were easily doped with $FeCl_3$. Doping of undrawn and drawn films of PCMPV homopolymer with $FeCl_3$ led to conductivity of $10^{-5}-10^{-4}\;Scm^{-1}$. Conductivity of $FeCl_3$-doped copolymer films ranged from $10^{-3}$ 4.0 Scm$^{-1}$ depending on composition. As the content of CMPV units in the copolymer increased further, the electrical conductivity steadly decreased. Electronic effect by the CN substituent and morphological changes brought by copolymerization appear to interplay intricately resulting in the observation of a maximum conducting composition.

• 대한화학회지
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• 제59권5호
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• pp.423-428
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• 2015

(1S)-(+)-10-camphorsulfonic acid (CSA) and HCl were used together as a binary dopant in the electrodeposition of polyaniline (PAni). (+)-CSA and HCl were added in different mole ratios (9:1 and 6:4). (+)-CSA-doped and binary-doped PAni exhibited markedly different ultraviolet-visible and circular dichroism spectral characteristics due to differences in their conformations. Distinct helical structures are observed in the scanning electron microscopy images of (+)-CSA-doped PAni. The X-ray diffraction pattern of (+)-CSA-doped PAni exhibited remarkably higher crystallinity than that of HCl-doped PAni which is associated with the helical ordering along the polymer chains. The conformational changes due to the binary doping in chiral PAni had a significant effect on its chiroptical and electrochemical properties, morphology, and crystallinity, thus determined its conductivity.

• 한국전기전자재료학회논문지
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• 제13권5호
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• pp.411-419
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• 2000

In this paper we have investigated the surface degradation by ultraviolet-irradiation in high-temperature vulcanized silicone rubber. Through the measurement of surface potential decay by corona-charging and of contact angle it is found that the change of surface electrostatic properties and the decrease of contact angle under UV-radiation. For the changes in micro-morphological and chemical structure of the UV-treated silicone rubber we utilized several analytical techniques such as SEM, ATR-FTIR,XPS. From this study it is shown that the chemical reactions(scissoring of side chain(S-$CH_3$) cross-linking and branching) occur on the surface of silicone rubber during the UV-irradiation. Also we obtained the results of the loss of low molecular weight chain by cross-linking and oxidation reaction.

• Bulletin of the Korean Chemical Society
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• 제20권12호
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• pp.1457-1463
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• 1999

Structure and their redox property of the vanadium oxides prepared by decomposing NH₄VO₃ at various temperatures were studied by XRD, SEM, XPS, and temperature programmed reduction/temperature programmed oxidation (TPR/TPO) experiment. All TPR profiles have two sharp peaks in the temperature range 650-750℃, and the area ratio of the two sharp peaks changed from sample to sample. There were three redox steps in TPR/TPO profiles. The oxidation proceeded in the reverse order of the reduction process, and both the reactions proceeded via quite a stable intermediates. The changes of the morphological factor $(I_{(101)}/I_{(010)})$, the ratio of $O_{1S}$ peak area (O$_{1S}$( α)/O$_{1S}$( β)) in the XPS results, and the ratio of hydrogen consumption in TPR profiles with various vanadium oxides showed the distinct relationship between the structural property and their redox property of vanadium oxides. The change of the specific yield of phthalic anhydride with various vanadium oxides showed a very similar trend to those of the peak area ratio in TPR profiles, which meant that the first reduction step related to the partial oxidation of o-xylene on the vanadium oxide catalyst.

• Bulletin of the Korean Chemical Society
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• 제6권4호
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• pp.218-221
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• 1985

Transient charging and discharging currents as well as space charge limited currents have been measured in biaxially stretched poly(vinylidene fluoride) film under various poling fields and temperatures. At low temperatures and short poling times, the I-V characteristics showed shallow trap behavior. When the current values extrapolated to the infinite time, the I-V characteristics indicate that the distribution of the trap energy levels is uniform or very broad. The abnormal suppression of current at higher poling voltages and the high discharge rate observed also in the same voltage range are attributed to the morphological changes due to dipole reorientation.