• Journal of the Korean Society of Food Science and Nutrition
• /
• v.33 no.5
• /
• pp.785-790
• /
• 2004

Kimchi is well known as a traditional Korean food containing various antioxidative compounds and it has been demonstrated that dietary kimchi inhibit the tissue oxidation and aging in many related studies. Ultraviolet B (UVB) radiation is the most potent among the many related factor to skin photo-aging. This experiment is designed to elucidate the inhibitory effect of solvent fractionation of various kimchi on UVB induced oxidation and erythema formation. Among solvent fractions, phenol content mostly existed in dichloromethane / ethylacetate fraction of buchu kimchi, dichloromethane fraction of Korean cabbage kimchi and ethylacetate / dichloromethane fraction of mustard leaf kimchi. Free radical scavenging activities were higher in dichloromethane and ethylacetate fraction from buchu kimchi, dichloromethane fraction from Korean cabbage kimchi, and ethylacetate fraction from mustard leaf kimchi. When the damage of photo-oxidation by UVB irradiation was tested in the presence of solvent fractions of kimchi, dichloromethane / ethylacetate fraction of buchu kimchi, ethylacetate fraction from Korean cabbage and from mustard leaf kimchi showed the higher protective activities than others. The erythema formations which were induced by UVB irradiation were decreased in solvent fractions of kimchi that hate higher antioxidant activities. In conclusion, kimchi solvent fractions having antioxidant compounds mostly inhibited photo-oxidation and erythema formation by UV-irradiation, therefore kimchi consumption can retard skin aging due to the presence of antioxidative compounds.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.28 no.9
• /
• pp.1270-1275
• /
• 2004

Standard positive photoresist techniques were adapted to generate nano-scale patterns of gold substrate using self-assembled monolayers (SAMs) and femtosecond laser. SAMs formed by the adsorption of alkanethiols onto gold substrate are employed as very thin photoresists, Alkanethiolates formed by the adsorption of alkanethiols are oxidized on exposure to UV light in the presence of air to alkylsulfonates. Specifically, it is known that deep UV light of wavelength less than 200nm is necessary for oxidation to occur. In this study, ultrafast laser of wavelength 800nm and pulse width 200fs is applied for photolithography. Results show that ultrafast laser of visible range wavelength can replace deep UV laser source for photo patterning using thin organic films. Femtosecond laser coupled near-field scanning optical microscopy facilitates not only the patterning of surface chemical structure, but also the creation of three-dimensional nano-scale structures by combination with suitable etching methods.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.34 no.2
• /
• pp.75-82
• /
• 2008

In this study, the photocatalysed degradation of safranin-O was investigated using Au colloids. Au metal nanoparticle wasused to eliminate safranin-O fast in solution. Au nanoparticles were prepared reduction method using $Na_2CO_3$ and PVP in aqueous solution. The degradation of safranin-O was examined using a variety of condition such as concentration of Au colloid or Au salt, reaction pH, and reaction time in the presence of UV light and $H_2O_2$. As the concentration of Au colloid increases, the rate of dye degradation increases. The photo-oxidation of the safranin-O was monitored spectrophotometrically. The properties of Au nanoparticles were characterized by UV-Vis spectroscopy. In addition, catalytic capacities of Au nanoparticles were also determined by UV-Vis spectroscopy.

• Journal of Environmental Science International
• /
• v.29 no.12
• /
• pp.1213-1222
• /
• 2020

In the current study, a Cu2O/TiO2 photoinduced nanocomposite materials prepared by ultrasonification method was evaluated the photocatalytic oxidation efficiency of volatile organic compounds (BTEX) under visible-light irradiation. The results of XRD confirmed the successful preparation of photoinduced nanocomposite materials. However, diffraction peaks belonging to TiO2 were not confirmed for the Cu2O/TiO2. The possible reason for the absence of Cu2O peak is their low content and small particle size. The result of uv-vis spectra exhibited that the fabricated Cu2O/TiO2 can be activated under visible light irradiation. The FE-SEM/EDS and TEM showed the formation of synthesized nanocomposites and componential analysis in the undoped TiO2 and Cu2O/TiO2. The photocatalytic oxidation efficiencies of benzene, toluene, ethylbenzene, and o-xylene with Cu2O/TiO2 were higher than undoped TiO2. According to light sources, the average oxidation efficiencies for BTEX by Cu2OT-0.5 were exhibited in the orer of 8 W day light > violet LEDs > white LEDs. However, the photocatalytic oxidation efficiencies normalized to supplied electric power were calculated to be in the following order of violet LEDs > white LEDs > 8 W day light, indicating that the LEDs could be a much more energy efficient light source for the photo-oxidation of gaseous BTEX using Cu2O/TiO2.

• Journal of the Korean Chemical Society
• /
• v.29 no.6
• /
• pp.582-591
• /
• 1985

The thin films of Ti$O_{2-x}$, were prepared by vapor oxidation and Ti$O_2$ single crystal was reduced by heating in argon atmosphere. The photo-electrochemical properties of these samples were studied. When the photocurrent was scanned in 1M NaOH electrolyte solution, several peaks were observed in the vicinity of 320nm in the UV-region and in the vicinity of 520nm, 620nm, and 740nm in the visible-region. Contrary to the previous suppositions, those peaks were produced by the second-order lines from the grating monochromator.

• Environmental Analysis Health and Toxicology
• /
• v.22 no.3
• /
• pp.189-196
• /
• 2007

[ $TiO_2$ ] is widely used because it is non-toxic. Recently, however, nanometer size $TiO_2$ particles (P-25) have been produced and used to increase the photo catalysis efficiency. Nanometer-sized $TiO_2$ is efficient, but due to its small size ($20{\sim}30\;nm$), it can flow into ecosystems and into cells. Thus, it may affect human health. Additionally, $TiO_2$ can produce a second contaminant, OH-radical, which is a health risk for all living organisms during photo degradation reaction. Hence, when nanometer-sized $TiO_2$ flows into natural streams and attaches to living organisms, it will create health risks. We investigated the biological toxicity of this condition in zebrafish embryos. We observed abnormal morphology, hatching rate, and measured the catalase activity to determine anti-oxidation at 100 post fertilization hours. Zebrafish were somewhat affected by $TiO_2$ nanometer sized particles under UV-A (a condition similar to sunlight). Powdered $TiO_2$ is toxic to the zebrafish fly. Even without light, $TiO_2$ particles attached to embryos and flies, having an effect on both.

• Bulletin of the Korean Chemical Society
• /
• v.29 no.1
• /
• pp.159-164
• /
• 2008

Two kinds of CNT/TiO2 composite photocatalysts were synthesized with multi-walled carbon nanotubes (MWCNTs) and titanium(IV) n-butoxide (TNB) by a MCPBA oxidation method. Since MWCNTs had charge transfer and semiconducting, the CNT/TiO2 composite shows a good photo-degradation activity. The XRD patterns reveal that only anatase phase can be identified for MCT composite, but the HMCT composite synthesized with HCl treatment was observed the mixed phase of anatase and rutile. The EDX spectra were shown the presence as major elements of Ti with strong peaks. From the SEM results, the sample MCT and HMCT synthesized by the thermal decomposition with TNB show a homogenous sample with only individual MWCNTs covered with TiO2 without any jam-like aggregates between CNTs and TiO2. From the photocatalytic results, we could be suggested that the excellent activity of the CNT/TiO2 composites for organic dye and UV irradiation time could be attributed to combination effects between TiO2 and MWCNTs with plausible photodegradation mechanism.

• Journal of Korean Society on Water Environment
• /
• v.20 no.5
• /
• pp.488-493
• /
• 2004

The effects were examined from several conditions of $TiO_2$ photocatalysis reaction to phenols degradation by changing it's reacting conditions such as phenol concentration, pH, $TiO_2$ concentration, $H_2O_2$ concentration, flow rate, and intensity of ultraviolet rays. Phenol degradation was more efficient in low concentration of phenol, neutral pH. Phenol degradation appeared to increase as concentration of $TiO_2$ photocatalyst, that of $H_2O_2$ and intensity of ultraviolet rays increased. As $TiO_2$ dosage increased, initial rate constant k linearly increased. When $H_2O_2$ was injected more than optimum, phenol removal rate didn't increase in proportional to the change of $H_2O_2$ concentration as OH radicals was being consumed. When flow rate is less than $4.75m^3/m^2$ day, phenol removal efficiency appeared to decrease as ultraviolet rays transmission rate becomes low by $TiO_2$ suspension coated in photo reaction column. Meanwhile, initial rate constant according to light intensity change in less than $25mW/cm^2$ appeared to be in proportion to light intensity ($mW/cm^2$) Removal efficiency decreased about 12% after 180 minutes of reaction time while showed stable removal efficiency of 100% after 300 minutes when using regenerated $TiO_2$.

• Journal of Korean Society of Environmental Engineers
• /
• v.27 no.4
• /
• pp.377-384
• /
• 2005

Algae causes not only the eutrophication of lake, but also the deterioration of drinking water process. Especially, algogenic organic matters(AOM) are assumed as disinfection by-products(DBPs) precursors like humic and fulvic acids. In this study, it was investigated the characteristics changes of algogenic organic matter(AOM) by prechlorination and coagulation treatment. Evaluation of enhanced coagulation and applicability of UV oxidation process were also evaluated as the drinking water treatment system for the eutrophicated water source. prechlorination was effective process for algae removal but caused releasing of dissolved organic matter(DOC) into water due to the destruction of algae's cell. In coagulation treatment with Fe(III) coagulant, reaction pH is an important factor for the removal of AOM and triholomathanes(THMs). At pH 5, removal efficiency of DOC and THMs were dramatically improved by 50% and 28%, respectively, in comparison with the conventional coagulation treatment at about pH 7. Photo-Fenton($UV/H_2O_2/Fe^{3+}$) process among the UV oxidations is the most effective system to remove AOM, but its removal efficiency was lower than that of enhanced coagulation treatment at pH 5.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.45 no.2
• /
• pp.209-216
• /
• 2019

Ultraviolet rays (UV) cause photoaging by inducing skin photodamages such as erythema and sunburn. Silymarin is a mixture of antioxidant polyphenols extracted from Silybum marianum fruit (S. m), which is known as milk thistle. It is known to protect skin tissues from UV treatment and antioxidant effects. In this study, we aimed to identify the photoprotective effects of S. m extract, which has silymarin in the epidermis layer of the skin. We found that the extract can function as a UV filter, so it can reduce DNA damage by UV treatment. Especially, we found that, in the stratum corneum, the extract can suppress the protein carbonylarion and DNA damages caused by suberythemal dose of UV treatment which does not induce erythema in the skin. UV treatment also increased protein carbonylation levels in the stratum corneum by oxidation, but it was prevented by applying the extract. The extract can absorb UV with minimal phototoxicity. Together, our study suggests that S. m extract can be used as a photo-protective ingredient to avoid photoaging of the skin.