• Journal of Electrochemical Science and Technology
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• v.15 no.2
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• pp.276-290
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• 2024

A study of the transition from transitory state to steady state in DSSCs based on natural dyes is presented; cochineal was used as dye and Li⁺, Na⁺, and K⁺ were the ions added to the electrolyte. The photocurrent profiles were obtained as a function of time. Several DSSCs were prepared with different cations and their role and the transitory-to-steady transition was determined. A novel hybrid charge carrier source model based on the Heaviside function H(t) and the Lambert-Beer law, was developed and applied to analysis of the transient response of the output photocurrent. Additionally, the maximum effective light absorption coefficient α and the electronic extraction rate κ for each ion were determined: ${\alpha}_{Li^+,Na^+,K^+}\,=\,(0.486,\,0.00085,\,0.1126)\,cm^{-1}$, and also the electronic extraction rate ${\kappa}^{Li^+,Na^+,K^+}_{ext.}\,=\,(1410,\,19.07,\,19.69)\,cm\,s^{-1}$. The impedance model using Fick's second law was developed for carrier recombination to characterize the photocurrent.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.12
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• pp.1-7
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• 2001

Single-layer polymer green electroluminescent devices were fabricated with novel material synthesis by using moleculely-dispersed TTA and NIDI into the polymer PC(B79) emitter layer doped with C6 fluorescent dye which has low operating voltage and high quantum efficiency. A EL cell structure of glass substrate/indium-tin-oxide/PC:TTA:NIDI:C6/Ca/Al was employed and compared with various low work function cathode electrodes Ca and Mg metals. By adjusting the concentration of the fluorescent dye C6, low turn-on voltage of 2.4V was obtained, maximum quantum efficiency of 0.52% at 0.08mole% has been improved by about a factor of ~50 times in comparison with the undoped cell. The PL and EL colors can't be turned by changing the concentration of the C6 dopant. PL emission peaking was obtained at 495nm and EL emission peaking at 520nm with FWHM ~70nm

• Toxicological Research
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• v.26 no.1
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• pp.29-35
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• 2010

The present study was conducted to investigate the antimutagenic potential of the methanolic extract from the leaves of sweet potato (Ipomea batatas, IB) with the SOS chromotest (umu test) and Salmonella typhimurium TA 98 and TA 100. The anticarcinogenic effects were also studied by calculation of the $IC_{50}$ on human cancer cell lines and investigating the function of gap junction in rat liver epithelial cells. The IB extract inhibited dose-dependently the ${\beta}$-galactosidase activity induced spontaneously at concentration of more than 200 mg/ml in S. typhimurium TA 1535/pSK 1002, and decreased significantly (p < 0.01) the ${\beta}$-galactosidase activities induced by mutagen 6-chloro-9-[3-(2-chloroethylamino)proylamino]-2-methoxyacridine dihydrochloride (ICR) at dose of more than 0.4 mg/0.1 ml. The IB extract showed no effect on the spontaneous reversions of S. typhimurium TA 98 and 100 but benzo(${\alpha}$)pyrene (BaP)-stimulated reversions were decreased dose-dependently (p < 0.01) at the concentration of more than 100 mg/ml. The $IC_{50}$ value of stomach cancer cells was lower than that of normal rat liver epithelial cells, but the values of colon and uterine cancer cell lines were similar to those of normal rat liver epithelial cells. The transfer of dye through gap junctions was not affected by treatment of the IB extracts at any concentration during treatment periods. The simultaneously treatment of IB extract and 12-O-tetradecanoylphorbol-13-acetate (TPA) effectively prevented the inhibition of dye transfer induced by TPA 1 hour after treatment at all exposed concentrations. The number of gap junctions was significantly (p < 0.01) increased by the treatment with IB extract at concentrations of more than 40 ${\mu}g$/ml. The inhibition of the expression of gap junction proteins by TPA (0.01 ${\mu}g$/ml) was recovered dose dependently by the simultaneous treatment of IB extracts. Our data suggest that Ipomea batatas has antimutagenic and anticarcionogenic activity in vitro.

• Wind and Structures
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• v.31 no.3
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• pp.229-240
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• 2020

In the present work, the main features of primary vortices and the vorticity concentrations downstream of vortex bursting in crossflow plane of a delta wing with a sweep angle of Λ=70° were investigated under the variation of the sideslip angles, β. For the pre-review of flow structures, dye visualization was conducted. In connection with a qualitative observation, a quantitative flow analysis was performed by employing Particle Image Velocimetry (PIV). The sideslip angles, β were varied with four different angles, such as 0°, 4°, 12°, and 20° while angles of attack, α were altered between 25° and 35°. This study mainly focused on the instantaneous flow features sequentially located at different crossflow planes such as x/C=0.6, 0.8 and 1.0. As a summary, time-averaged and instantaneous non-uniformity of turbulent flow structures are altered considerably resulting in non-homogeneous delta wing surface loading as a function of the sideslip angle. The vortex bursting location on the windward side of the delta wing advances towards the leading-edge point of the delta wing. The trajectory of the primary vortex on the leeward side slides towards sideways along the span of the delta wing. Besides, the uniformity of the lift coefficient, C_L over the delta wing plane was severely affected due to unbalanced distribution of buffet loading over the same plane caused by the variation of the sideslip angle, β. Consequently, dissimilarities of the leading-edge vortices result in deterioration of the mean value of the lift coefficient, C_L.

• Korean Chemical Engineering Research
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• v.54 no.2
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• pp.255-261
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• 2016

Adsorption experiments of Acid Yellow 14 dye using activated carbon were carried out as function of adsorbent dose, pH, initial concentration, contact time and temperature. The equilibrium adsorption data were analyzed by Langmuir, Freundlich and Temkin isotherm model. The experimental data were best represented by Freundlich isotherm model. Base on the estimated Freundlich constant (1/n=0.129~0.212) and Langmuir separation factor ($R_L=0.202{\sim}0.243$), this process could be employed as effective treatment method. The heat of adsorption of Temkin isotherm model was 5.101~9.164 J/mol indicated that the adsorption process followed a physical adsorption. Adsorption kinetics experimental data were modeled using the pseudo-first-order and pseudo-second-order kinetic equation. It was shown that pseudo-second-order kinetic equation could best describe the adsorption kinetics. Base on the negative Gibbs free energy (-4.81~-10.33 kJ/mol) and positive enthalpy (+78.59 kJ/mol) indicate that the adsorption is spontaneous and endothermic process.

• Journal of the Korean Society of Clothing and Textiles
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• v.42 no.3
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• pp.516-529
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• 2018

This study investigated the dyeing properties and bio-functions of cotton fabrics dyed with naturally fermented Ecklonia cava extract in order to compare it with a comparison of unfermented extract. Hot water-extracted Ecklonia cava was fermented naturally under the various conditions of a fermenting period (2-8 days) and amount of molasses (0.1-1.8% v/v); in addition, it was also tested for characterization by FT-IR, antioxidant activity, total polyphenol content, and anti-microbial activity. For dyed cotton fabrics, color strength (K/S), physical color properties, dyeing fastness, sun protective property, and anti-microbial activity were evaluated considering dyeing conditions. As a result, the fermented dye under fermentation condition of 0.1% v/v with molasses during 4 days was revealed as having a similar chemical structure to the unfermented one and showed a total polyphenol content with 32.88mg/g and better antioxidant activity than the unfermented one. As for dyed fabrics, the color strength value by K/S was the highest under the condition of 0.1% v/v of molasses during 4 days among all fermenting conditions. The dyed fabrics had a reasonably good fastness (except for light). Anti-microbial activity against K. pneumoniae was better for the fermented extract-dyed fabric especially with lower dye concentrations.

• Korean Journal of Optics and Photonics
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• v.4 no.2
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• pp.212-219
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• 1993

To reduce the mode noise induced from a multimode dye laser, a modeless laser generating amplified spontaneous emission was used as Stokes beam of the broadband CARS. A new technique for measuring species concentration from the modulation dip of nonresonant background of broadband CARS spectrum was proposed. The modulation dip was numerically calculated and fitted as a function of the concentration of the minor species and temperature of gas sample. We applied this technique in measuring CO concentration in a static cell and also the profile of CO concentration in a CHdair premixed flame of a counterflow burner.

• Microbiology and Biotechnology Letters
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• v.25 no.1
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• pp.37-43
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• 1997

Triphenylmethane was decolorized rapidly by enterbacter cloacae MG 82 at initial reaction time. The spheroplast showed higher activity of triphenylmentane decolorization than that of intact cell suspension. The outer part of the bacterial cell envelope and the peptidoglycan are important for the function of transport barrier of triphenylmethane. In intact cell, decolorization activity was higher at 37$\circ $C than at $\circ $C, indicating that triphenylmethane decolorization is due to the enzyme reaction. Culture filtrate showed no decolorization activity, while cell-free extract appeared high activity of 1.45 units, clearly showing that decolorization activity was due to the cell-free extract. Comparing decolorization activities of cell fractions, it was found that decolorization activity was located at the compartment of cytoplasmic membrane. The enzyme activity was also shown to be Mg$^{++}$-dependent. The optimum pH and temperature of enzyme activity were 7.0 and 50$\circ $C, respectively. The thermostability of this enzyme at 35$\circ $C was kept to 58% for 3 hours.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.35 no.5
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• pp.37-45
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• 2003

To investigate the influence of the design and operating parameters of the headbox on hydrodynamics, a pilot headbox system and pressure monitoring apparatus were constructed. The pilot headbox system consisted of a circulating water reservoir, centrifugal pump, distributor, turbulence generator and slice. The distributor was designed to function as a pressure attenuator. Flow rate to the headbox and MD and CD velocity profiles in the slice zone were monitored using an ultrasonic flowmeter and Pitot tubes, respectively. As the distance from the step diffusor increased, evener CD velocity profile was observed. Wall effect increased with the increase of the velocity. Flow stability in the headbox was evaluated by injecting a dye at the outlet of the distributor. Application of theoretical analysis based on CFD in designing headboxes is briefly discussed.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 1999.04b
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• pp.381-385
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• 1999

To investigate the influence of the design and operating parameters of the headbox on hydrodynamics, a pilot headbox system and pressure monitoring apparatus were constructed. The pilot headbox system consisted of a circulating water reservoir, centrifugal pump, distributor, step diffusor and slice. The distributor was designed to function as a pressure attenuator. Flow rate to the headbox and MD and CD velocity profiles in the slice zone were monitored using an ultrasonic flowmeter and Pitot tubes, respectively. As the distance from the step diffusor increased, evener CD velocity profile was observed. Wall effect increased with the increase of the velocity. Flow stability in the headbox was evaluated by injecting a dye at the outlet of the distributor. Application of theoretical analysis based on CFD in designing headboxes is briefly discussed.