• Bulletin of the Korean Chemical Society
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• v.35 no.11
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• pp.3313-3318
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• 2014

The reaction mechanism of Lead ions catalyzing complexation reactions between TIPP and metal ions was investigated by researching the kinetics of the formation of metalloporphyrins by UV/Vis-spectra, and verified by exploring the formation of metalloporphyrins catalyzed by acetic acid. Kinetics studies suggested that the fluctuations of reaction rate indicated the formation of metalloporphyrin was step-wise, including the pre-equilibrium step (the coordination of the pyrrolenine nitrogens to $Mn^+$) and the rate-controlling step (the deprotonation of the pyrrole proton). In the pre-equalization step, a sitting-atop (SAT) structure formed first with the complexation between larger radius of $Pb^{2+}$ and TIPP, changed the activation, then $Pb^{2+}$ left with the smaller radius of metal ions attacking from the back of the porphyrin ring center. In the rate-controlling step, two pyrrole protons dissociated to restore a stable structure. This was verified by adding acetic acid at different reaction times.

• Korean Journal of Pharmacognosy
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• v.11 no.2
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• pp.66-68
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• 1980

Paeonol-glycoside could be extracted and isolated from the fresh roots of Pycnostelma paniculatum Kitagawa and compared with paeonolide(paeonol-6-[L-arabinosyl]-${\beta}-D-glucoside)$ by IR and UV spectra. By saponification with mineral acid, it was known that isolated glycoside was composed of aglycon and sugar parts. Aglycon was identified by comparing with paeonol by TLC and UV spectra. Of two kinds of sugar, only glucose was identified by GLC.

• Textile Coloration and Finishing
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• v.11 no.4
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• pp.39-49
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• 1999

In order to study the properties of cochineal colors, uv-visible spectra of cochineal colors solution, dyeing properties on the wool in several dyeing conditions and thermodynamic parameters were investigated. UV-visible spectra of cochineal colors solution showed hypochromic effect with the lapse of irradiation time but bathochromic shift with decreasing acidity of solution and addition of metallic ions. The concentration of cochineal colors in wool fiber increased with the increase of dyeing temperature, time, and acidity of initial dyebath. The value of apparent diffusion coefficients and standard affinities of dyeing decreased with the increase of dyeing temperature. The standard heats of dyeing$(\Delta{H}^\circ)$ and variation of entropy$(\Delta{S}^\circ)$ increased with the increase of concentration of initial dyebath. The activation energy$(E_a)$ were calculated to be 1.399~2.595kcal/mol in condition of 6~1%(o.w.f) dyebath. Wool fabrics were dyed reddish blue by iron sulfate, copper sulfate, aluminum acetate and tannic acid, and red by tin chloride, respectively. Lightfastness of wool fabrics dyed by cochineal colors were increased by mordant treatment, especially copper sulfate and iron sulfate treatment.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.29-30
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• 2000

CaS:Pb thin film used as phosphor layer in electroluminescent devices were deposited by an atomic layer deposition (ALD). The photoluminescence emission and excitation spectra were measured at 5 and 300K for the $CaS:Pb^{2+}$ phosphors with different Pb concentration from 0.001 at.% to 0.648 at.%. The emission spectra of these samples were characterized as UV emission and blue emission with the center of peak around 360 and 425nm, respectively. The UV emission was dominant at the low $Pb^{2+}$ concentration of 0.001 at%, whereas with increase of Pb concentration, the blue emission became a major component and to longer wavelength.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.35-36
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• 2000

The luminescence behaviors of Yttrium niobate and Bi doped Yttrium niobate were investigated under UV and low voltage electron excitations and interpreted with the first-principle calculations. In the UV excitation and emission spectra of $YNbO_4$ and $YNbO_4:Bi$, we were able to separate host contribution and Bi contribution and found that the shift in emission peak to longer wavelength is mainly due to Bi contribution. Using density functional theory, the cluster calculations were carried out for both $YNbO_4$ and $YNbO_4:Bi$. From the calculated density of states, we were also able to explain the charge transfer gap in the host and the effect of Bi in the excitation and emission spectra theoretically.

• Bulletin of the Korean Chemical Society
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• v.34 no.1
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• pp.231-236
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• 2013

Some cytotoxicity studies for the interpretation of the interaction between nanoparticles and cells are non-mechanistic and time-consuming. Therefore, non-biological screening methods, which are faster and simpler than in-vivo and in-vitro methods, are required as alternatives to current cytotoxicity tests. Here, we proposed a simple screening method for the analysis of the interaction between several AgNPs (bare-, citrate-, and polyvinylpyrrolidone-coating) and dye-containing vesicles acting as a biomimetic cell-membrane. The interaction between AgNPs and vesicles could be evaluated readily by UV-vis spectra. Absorbance deviation in UV-vis spectra revealed a large attraction between neighboring particles and vesicles. This was confirmed by (Derjagin, Landau, Verwey, and Overbeek) theory and DMF (dark-field microscopy) analysis. This proposed method might be useful for analyzing the cytotoxicity of nanoparticles with cell-membranes instead of in vitro or in vivo cytotoxicity tests.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.475-478
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• 2000

Maxwell displacement current(MDC) was generated when the area per molecule was about 140${\AA}$$^2$and 100${\AA}$$^2$. MDC were investigated in connection with monolayer compression cycles. It was found that the maximum of MDC appeared at the molecular area just before the initial rise of surface pressure in compression cycles. The absorption spectra of polyamic acid containing p-methoxyazobenzene in a mixture of N,N-dimethylacetamide(DMAc) and benzene(1:1 by volume) solution was induced photoisomerization by UV and visible light irradiation. The precursor LB film was heated in a vacuum dry oven at 120$^{\circ}C$ in order to convert it into the LB film of polyimide. The absorption spectra of LB films were also induced photoisomerization by UV and visible light irradiation.

• Journal of Photoscience
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• v.12 no.1
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• pp.11-15
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• 2005

The mechanism of interaction of two drugs viz., amoxicillin and cloxacillin with bovine serum albumin has been investigated using fluorescence absorption and circular dichroism spectroscopy. The quenching mechanism of fluorescence of bovine serum albumin by amoxicillin and cloxacillin was discussed. The binding sites number n and apparent binding constant Kwere measured by fluorescence quenching method. The thermodynamic parameters obtained from data at different temperatures were calculated. The distance r between donor (bovine serum albumin) and acceptor (amoxicillin and cloxacillin) was obtained according to Forster theory of non-radiative energy transfer. The effect of common ions on binding constant was also investigated. The results of synchronous fluorescence spectra, UV-vis absorption spectra and circular dichroism of BSA in presence of amoxicillin and cloxacillin show that the conformation of bovine serum albumin changed

• Journal of the Korean Chemical Society
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• v.67 no.4
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• pp.217-221
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• 2023

A series of hydrophobic dodecyl-terminated 6th-generation poly(amidoamine) dendrimer (H)-encapsulated cadmium sulfide ((CdS)_n@H) nanoparticles in a co-solvent (toluene: methanol = 6.8: 3.2 v/v) are synthesized. The diameters of CdS nanoparticles within the dendrimer were estimated by analyzing the positions of the first excitonic absorption peaks of CdS in UV-vis spectra. The size of the CdS nanoparticle within the dendrimer shows a saturation value as the CdS/H ratio (n) increases, which is believed to be due to the limited physical size of the void cavity within the dendrimer. This simple and convenient method of estimating the saturation of the size of CdS in dendrimers may be useful in determining the maximum void space within other dendrimers under various solvent conditions.

• Journal of the Korean Vacuum Society
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• v.17 no.2
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• pp.138-147
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• 2008

$SiO_2/TiO_2/ZrO_2$ broadband anti-reflective multi-layer thin films were prepared at room temperature by RF sputtering system. Optical constants and structural properties on each layer of films were analyzed by spectroscopic ellipsometer and transmittance spectra of the films were measured by $UV-V_{is}$ spectrophotometer in the range of 300$\sim$900 nm. To evaluate the films, we compared the measured and analyzed spectra with designed spectra. We investigated influence of discrepancy of thickness and refractive indices of each layer on changes of the transmittance spectra. It was found that refractive indices and shape of dispersion of deposition materials are more contributed to changes of the transmittance spectra than thickness of layer.