• E2M - 전기 전자와 첨단 소재
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• 제8권4호
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• pp.458-463
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• 1995

The optical and electrical properties of $C_{22}$-Quinolinium(TCNQ) Langmuir-Blodgett films have been studied depending on the annealing temperatures. The optimal properties were investigated using UV/visible(300-800[nm]) absorption spectra and FTIR(Fourier-transformed- infrared) absorption measurements. The electrical properties were investigated in a frequency range of 10[Hz]-13[MHz]. The UV/visible absorption spectra at room temperature show that there are four characteristic peaks at 320, 380, 494 and 678[nm]. These absorption peaks decrease very rapidly above the annealing temperature of 180[.deg. C], which is due to a structural change of TCNQ. The FTIR absorption measurements strongly support the result of the UV/visible absorption spectra, because the absorption peak of TCNQ- at 2181[$cm^{-1}$ /] also decreases above 140[.deg. C]. The frequency-dependent dielectric constant shows that there is a dielectric dispersion near 1[MHz] which is due to an orientational polarization of the molecules inside the film. The overall frequency-dependent dielectric constant is higher near 80[.deg. C]. It may be due to a softness of the alkyl chains.s.

• Journal of Pharmaceutical Investigation
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• 제26권2호
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• pp.83-89
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• 1996

A reverse-phase HPLC method to determine DL-Carnitine Hydrochloride in pharmaceutical preparation is described. UV absorption derivatives of DL-Carnitine Hydrochloride were formed with p-Bromophenacyl Bromide in an essentially quantitative manner using crown ether as catalyst. The DL-Carnitine-bromophenacyl ester absorbed UV radiation strongly at 254nm, allowing the detection of as small a quantity as 12.5ng of DL-Carnitine Hydrochloride. A linear defection range was $5\;{\times}\;10-8 \;{\sim}\;5\;{\times}\;10-7M$ of DL-Carnitine Hydrochloride. And the linear regression at various drug concentration was =0.999 (n=10). The DL-Carnitine Hydrochloride in pharmaceutical preparation was successfully derivatized and separated from other constituents by reverse phase HPLC with detection at 254 nm.

• 한국식품영양학회지
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• 제7권4호
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• pp.332-337
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• 1994

The antioxidant activity of solvent extracts isolated from barley leaves was investigated by measuring peroxide value. The fractions of methanol extract obtained from preparative TLC was also studies, with UV-Visible spectrum, total phenol contents and hydrogen donating ability(HDA) The antioxidant activity of various solvent extracts was, in decreasing order, methanol> ethyl ether> methylene chloride $\geq$ ethyl acetate $\geq$acetone> hexane. The antioxidant activity of the fractions of methanol extract was, in decreasing order, fraction 2> fraction 3> fraction 1 and their activity was all superior to that of tocopherol at 500 ppm level. All fraction(1, 2 and 3) exhibited a strong UV absorption at 280 m which would be specifically produced by phenolic compound. UV absorption at 280 m of fraction 2 was greater than those of fraction 1 and 3. In the visible spectrum of these fractions, the maximum .absorption wavelengths of fraction 1, 2 and 3 were 660, 460 and 460 m, respectively. Antioxidant activity of barley leaves seemed to be due to the flavonoids containing phenolic group by UV spectrum and total phenol content.

• Bulletin of the Korean Chemical Society
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• 제33권2호
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• pp.597-600
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• 2012

Polyynes were formed by laser ablation of a graphite target in deionized water ($H_2O$ and $D_2O$) and various organic solvents such as acetonitrile, n-hexane, and c-hexane and were identified by analyzing ultraviolet (UV) absorption and Raman spectra. We assigned the major UV absorption peaks that coincided with the electronic transitions corresponding to linear polyyne chains. The UV absorption peak intensities of a polyyne solution decreased as the holding temperature of the solution increased. Also, the absorption spectra of polyynes obtained by laser ablation of a graphite target at different volume fractions of $H_2O$ and $D_2O$ were examined.

• Fisheries and Aquatic Sciences
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• 제15권4호
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• pp.361-363
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• 2012

We investigated ultraviolet (UV) absorption materials from Russian seaweeds. First, the UV absorptivities of five seaweeds Gloiopeltis fucatas, Mazzaella sp., Mastocarpus pacificus, Laminaria cichorioides, Saccharina japonica were evaluated by a UV spectrometer. Of these seaweeds, Gloiopeltis fucatas and Mazzaella sp. showed high levels of UV absorption. Column chromatography of active 50% aqueous ethanol extracts from Gloiopeltis fucatas and Mazzaella sp. resulted in the purification of two known compounds. Spectroscopic techniques identified their structures as shinorine and palythine. These materials exhibited UV absorptive capabilities at wavelengths of 333 and 320 nm, respectively. These results suggest that Gloiopeltis fucatas and Mazzaella sp. may be useful as natural cosmeceutical sources.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1993년도 추계학술대회 논문집
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• pp.137-140
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• 1993

Electrical properties and thermal annealing effects of $C_{22}$-quinolium(TCNQ) Langmuir-Blodgett(LB) films were studied. Typical current-voltage(I-V) characteristics along the perpendicular direction chow an anomalous behavior of breakdown near the electric-field strength of $10^{6}$V/cm. To see the thermal influence of the specimen, current was measured as a function of temperature(20∼$180^{\circ}C$). It shows that the current increases about 4 orders of magnitude near 60∼$70^{\circ}C$ and remains constant far a while up to ∼$150^{\circ}C$ and then suddenly drops. Such increase of current near 60∼$70^{\circ}C$ seems tn be related to a softness of alkyl chains. Besides the electrical measurements, UV/visible absorption(300∼800 nm) of the thermally annealed sample was measured to see the internal-structure change. It is found that there are four characteristic peaks. At 494 nm, the optical absorption of the thermally annealed specimen at $60^{\circ}C$ starts increase and stays almost constant upto∼ $140^{\circ}C$. And eventually it disappears above $180^{\circ}C$. After heat treatment of the specimen up to $150^{\circ}C$, Uv/visible absorption was measured while cooling.

• 대한화장품학회지
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• 제36권4호
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• pp.259-263
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• 2010

화장품에서 일반적으로 사용되고 있는 대표적인 자외선차단 원료들과 방부제인 phenoxyethanol (PE), 항균효과가 있는 ethylhexylglyceirn (EG)의 분배계수와 흡착도를 측정하여 비교하였고, 제품의 포장재 재질에 따라 PE가 흡착되는 정도를 비교하였다. PE, EG에 대한 11개 자외선 차단제의 분배계수는 EG가 상대적으로 높게 나타났으며 그중 Tinsorb M, Solaveil CT434가 높은 분배계수를 보였다. 40 % 이상의 EG 흡착을 보인 자외선 차단 원료는 Gransil PSQ, UV Titan M 160, Micro $TiO_2$ MT 100 TV였고, Gransil PSQ와 Scadder는 40 % 이상의 PE를 흡착하였다. 또한 PE는 포장재 원료인 polyoxymethylene에 의해 1개월 후 7 ~ 8 % 흡착됨을 확인하였다. 자외선차단제품의 방부처방을 설계할 때 사용되는 자외선 차단제와 방부제와의 상관성을 고려하여 적절한 방부제 및 차단제를 선정해야 적은 방부제로도 최적의 방부력을 갖는 제품 설계가 가능함을 보여준다. 또한 포장재의 종류에 따라 시간이 경과하면서 방부제가 포장재에 흡착되어 방부력이 저하될 수 있음을 확인하였다.

• 한국결정성장학회지
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• 제16권1호
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• pp.25-31
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• 2006

남미, 아프리카, 아시아 대륙의 자수정을 대상으로 하였다 ICP-AES 분석에서 나타난 발색원소는 Fe, Cr, Cu, Co이며 대체적으로 남미 지역에서 발색원소의 함유량이 높게 나타났다. UV-VIS 분석결과 천연자수정과 합성자수정은 350nm 영역과 550nm 영역에서 흡수가 일어나는 특성을 나타냈고 투과율은 합성에 비해 천연이 낮게 나타났다. FT-IR분석결과 천연자수정과 합성자수정의 구분은 합성자수정의 특징인 $3543cm^{-1}$ 흡수밴드의 유무에 의해 알 수 있었다 남미 지역은 $3584cm^{-1},\;3435cm^{-1}$ 흡수밴드가 강하게 나타나며, 아프리카 지역은 $3299cm^{-1},\;3196cm^{-1}$ 흡수밴드가 나타났다. 아시아 지역은 $3381cm^{-1}$ 흡수밴드가 특징적으로 관찰되었다.

• 천문학회보
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• 제41권2호
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• pp.40.2-40.2
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• 2016

The attenuation of starlight by dust in galactic environments is investigated through models of radiative transfer in a spherical, clumpy interstellar medium (ISM). We show that the attenuation curves are primarily determined by the wavelength dependence of absorption rather than by the underlying extinction (absorption+scattering) curve; the observationally derived attenuation curves cannot constrain a unique extinction curve unless the absorption or scattering efficiency is specified. Attenuation curves consistent with the Calzetti curve are found by assuming the silicate-carbonaceous dust model for the Milky Way (MW), but with the $2175{\AA}$ bump suppressed or absent. The discrepancy between our results and previous work that claimed the Small Magellanic Cloud dust to be the origin of the Calzetti curve is ascribed to the difference in adopted albedos; we use the theoretically calculated albedos whereas the previous ones adopted empirically derived albedos from observations of reflection nebulae. It is found that the model attenuation curves calculated with the MW dust are well represented by a modified Calzetti curve with a varying slope and UV bump strength. The strong correlation between the slope and UV bump strength, as found in star-forming galaxies at 0.5 < z < 2.0, is well reproduced if the abundance of the UV bump carriers is assumed to be 30-40% of that of the MW-dust; radiative transfer effects lead to shallower attenuation curves with weaker UV bumps as the ISM is more clumpy and dustier. We also argue that some of local starburst galaxies have a UV bump in their attenuation curves, albeit very weak.

• 한국응용과학기술학회지
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• 제2권2호
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• pp.47-53
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• 1985

Correlation among the wax-pigment composites which is base vehicles for the crepas was investigated in terms of fadeness. The base wax synthesized and pigments are compounded with petroleum lubricant and exposed under carbon arc individually. The yellowing phenomenon was appeared on the reference papers coated with the spindle oil which was then exposed. The papers were again extracted with distilled water and pH of them were ranged between 6.2-6.5. Color difference from Adam-Nickerson equation, ${\vartriangle}E$ of base wax is 0.15 and that of spindle oil are varied from 0.66 to 15.62. Since the main components of the petroleum lubricant are aromatic hydrocarbons which have absorptions characteric of UV ranging from 240 to 280 nm, fadeness characteristics of the composites are largely depend upon the change of molecular structure of spindle oil by absorbing UV. Thus the spindle oil having the following physical properties has the better resistance of fadness and is recommended to use in compounding the base wax-pigment composites: ${\cdot}$ main component: paraffinic hydrocarbon ${\cdot}$ pour point: below - $15^{\circ}C$ ${\cdot}$ UV absorption characteristics: ${\lambda}max.$ : 268-290nm ${\cdot}$ absorbancy: below 0.1(0.03ml of sample/50ml of $CHCl_3$)