• Asian-Australasian Journal of Animal Sciences
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• 제14권9호
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• pp.1216-1220
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• 2001

Effect of hydroquinone (HQ) on rumen urease activity was studied. Hydroquinone at concentrations of 0.01 ppm, 0.1 ppm, 1 ppm, and 10 ppm inhibited urease activity of intact rumen microbes in vitro by 25%, 34%, 55% and 64% respectively. In the presence of low concentrations of $\beta$-mercaptoethanol, rumen urease could be solubilized and partially purified. The Km for the enzyme was $2{\times}10^{-3}$ M with Vmax of $319.4{\mu}moles/mg$ min. The kinetics of inhibition with partially purified rumen urease was investigated. The result showed that the inhibitory effect was not eliminated by increasing urea concentrations indicating a noncompetitive effect in nature with an inhibition constant $1.2{\times}10^{-5}$ M. Hydroquinone at the concentration of 10 ppm produced 64% urease inhibition, did not affect ruminal total dehydrogenase and proteolytic enzyme (p>0.05), but increased cellulase activity by 28% (p<0.05) in vitro. These results indicated that hydroquinone was a effective inhibitor of rumen urease and could effectively delay urea hydrolysis without a negative effect. The inhibitor appeared to offer a potential to improve nitrogen utilization by ruminants fed diets containing urea.

• 대한화장품학회지
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• 제30권3호
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• pp.415-418
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• 2004

알부틴은 glycosylated hydroquinone으로 여러 식물들에서, 고농도로 발견되며 비교적 안정한 물질이다. 이는 멜라닌화를 억제하는 작용이 있는 것으로 보고되어 있고, 베타-글루코시다제에 의해 포도당과 hydroquinone으로 쉽게 가수분해된다. Hydroquinone 역시 우수한 항멜라닌화 작용을 가지나, 여러 가지 부작용들로 인해 그 사용이 제한적이거나 주의를 요한다. 이 연구는 알부틴과 베타-글루코시다제를 포함하는 미백 화장품이 자외선 조사로 유도된 색소 침착을 억제하는 효과를 알아보고자 하였다. 대상은 10명의 건강한 성인으로 등 부위에 자외선 B를 조사하여 색소 침착 병변을 만들었고 이 병변들은 세 그룹: 알부틴과 베타-글루코시다제를 함유하는 미백 화장품 도포군, vehicle 대조군, no-application 대조군으로 나누었다. 알부틴과 베타-글주코시다제를 함유하는 미백 화장품 도포군은 no-application 대조군에 비교하여 색소 침착을 $50.17\%$ 억제하였다(N = 10:P<0.05). 따라서 알부틴과 베타-글루코시다제를 함유하는 미백 화장품이 기미 등 자외선 조사로 유도되거나 악화되는 과색소성 질환에 효과적으로 사용될 수 있겠다.

• 한국응용과학기술학회지
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• 제23권3호
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• pp.177-184
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• 2006

Because of the difference in the relative reactivity between two hydroxyl groups of the hydroquinone due to the steric hindrance of the substituent, many combinations of the substituent direction in the polyesters derived from asymmetrical diphenol such as monosubstituted hydroquinone was expected. It was studied how the mode of the direction affected the properties of the resulting polyesters in terms of the transition temperatures of the thermotropic polyesters prepared from terephthalic acid, 2,4-dichloroterephthalic acid and phenylhydroquinone by the reaction using diphenyl chlorophosphate in pyridine. The direction was tried to control the relative reactivity by changing the reaction temperature and the addition time of hydroquinone, and by modifying it through an association of hydroquinone with LiCl.

• 한국수소및신에너지학회논문집
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• 제27권5호
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• pp.540-546
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• 2016

Besides high-efficient photovoltaics based on silicon, polymers, dye-sensitization and hybrid perovskite materials, biomimetic solar cells inspired by a leaf in nature has also been actively studied. As one example, a hydrogel based photovoltaics (HGPV) is a low-cost, environmentally friendly device and requires easy fabrication process. In this paper, the effect of hydroquinone additive on the performance of the HGPV is discussed. The photocurrent increases ~14 times upon the addition of hydroquinone into the agarose hydrogel medium. The photocurrent increase is maximum at the optimum dye concentration, while the photovoltage is barely affected by the dye concentration. The effect of the agarose content in the hydrogel and the types of dyes on the photocurrent is also investigated. Finally, it is shown that the photovoltaic performance of HGPV with hydroquinone can be drastically improved when $TiO_2$ film is deposited on the anode electrode.

• Bulletin of the Korean Chemical Society
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• 제25권7호
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• pp.1081-1084
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• 2004

• Bulletin of the Korean Chemical Society
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• 제25권2호
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• pp.267-270
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• 2004

The bromate-1,4-cyclohexanedione-ferroin oscillating reactions are uncovered to support two types of wave activities, in which spontaneous formation of circular waves has been achieved after the disappearance of initial waves. The induction period of the revival wave is typically above 10 hours and its dependence on the initial concentrations of reactants is qualitatively different from that of initial waves. In addition to their differences in propagating speed and wavelength, the initial waves and the revival patterns have different colors, suggesting that different reaction mechanisms are involved in the formation of these spatiotemporal behaviors. Our experiments further show that the addition of hydroquinone to the reacting system can significantly shorten the induction time of the revival wave, which implicates that hydroquinone is not only a product in the bromate-1,4-cyclohexanedione-ferroin oscillating reaction but also plays a critical role in the following reactions.

• 한국산업융합학회 논문집
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• 제5권2호
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• pp.147-152
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• 2002

Because of the difference of the relative reactivity between two hydroxyl groups of the hydroquinone due to the steric hindrance of the substituent, many combinations of the substituent direction in the polyesters derived from asymmetrical diphenols such as monosubstituted hydroquinones was expected. It was studied how the mode of the direction affected the properties of the resulting polyesters in terms of the transition temperatures of the thermotropic polyesters prepared from terephthalic acid, 2,4-dichloroterephthalic acid, and phenylhydroquinone by the reaction using p-Toluenesulfonylchloride in pyridine. The direction was tried to control the relative reactivity by changing the reaction temperature and addition time of the hydroquinone, and by modifying it through an association of the hydroquinones with DMF.

• Bulletin of the Korean Chemical Society
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• 제34권2호
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• pp.421-425
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• 2013

The effect of pretreatment on indium-tin oxide (ITO) electrodes has been rarely studied, although that on metal and carbon electrodes has been enormously done. The electrochemical and surface properties of ITO electrodes are investigated after 6 different pretreatments. The electrochemical behaviors for oxygen reduction, $Ru(NH_3){_6}^{3+}$ reduction, $Fe(CN){_6}^{3-}$ reduction, and p-hydroquinone oxidation are compared, and the surface roughness, hydrophilicity, and surface chemical composition are also compared. Oxygen reduction, $Fe(CN){_6}^{3-}$ reduction, and p-hydroquinone oxidation are highly affected by the type of the pretreatment, whereas $Ru(NH_3){_6}^{3+}$ reduction is almost independent of it. Interestingly, oxygen reduction is significantly suppressed by the treatment in an HCl solution. The changes in surface roughness and composition are not high after each pretreatment, but the change in contact angle is substantial in some pretreatments.

• Journal of Electrochemical Science and Technology
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• 제3권1호
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• pp.24-28
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• 2012

The electrocatalytic activities and surface roughness of indium-tin-oxide (ITO) electrodes have been investigated after thermal treatment at 100, 150, or $200^{\circ}C$ for 30 min, 2 h, or 8 h. To check electrocatalytic activities, the electrochemical behavior of four electroactive species (p-hydroquinone, $Ru(NH_3){_6}^{3+}$, ferrocenemethanol, and $Fe(CN){_6}^{4-}$) has been measured. The electron transfer rate for p-hydroquinone oxidation and ferrocenemethanol oxidation increases with increasing the incubation temperature and the incubation period of time, but the rate for $Ru(NH_3){_6}^{3+}$ is similar irrespective of the incubation temperature and period because $Ru(NH_3){_6}^{3+}$ undergoes a fast outer-sphere reaction. Overall, the electrocatalytic activities of ITO electrodes increase with increasing the incubation temperature and period. The surface roughness of ITO electrodes increases with increasing the incubation temperature, and the thermal treatment generates many towering pillars as high as several tens of nanometer.

• 한국식품과학회지
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• 제22권6호
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• pp.625-631
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• 1990

사과로부터 추출한 산화효소와 5종의 polyphenol 화합물을 반응시켜 얻어진 사과효소 갈변반응 생성물(AEBRP)들의 항돌연변이 효과를 검토하기 위해 발암물질로 알려져 있는 N-methyl-N'-nitro-N-nitrosoguanidine(MNNG), mitomycin C(MMC), 4-nitroquinoline-1-oxide(4NQO), benzo(${\alpha}$)pyrene(B(${\alpha}$)P) 그리고 3-amino-1,4-dimethyl-5H-pyrido(4,3-b) indole(Trp-P-1)에 대한 다섯 종류의 사과효소 갈변반응 생성물들의 돌연변이 억제효과를 검토하였다. Bacillus subtilis Hl7과 M45 두 균주를 이용하는 spore rec-assay에서 homocate-chol-AEBRP와 hydroquinone-AEBRP는 농도증가에 따라 MMC와 MNNG에 대하여 강한 억제효과를 나타내었으며 Salmonella typhimurium TA98과 TA100 두 균주를 이용한 Antimutagenicity test에서는 hydroxyhydro-quinone-AEBRP와 pyrogallol-AEBRP는 S-9mix 첨가시 두 균주에서 Trp-P-1과 B(${\alpha}$)P에 대하여 강한 억제효과를 나타내었다. 그리고 대부분의 AEBRP들은 MNNG로 유도된 TA98주에서 $50%{\sim}80%$의 억제효과를 나타내었으나 hydroxy-hydroquinone-AEBRP를 제외한 네 종류의 AEBRP들은 TA100 균주에서 약 94%의 억제효과를 나타내었다. 한편, 4NQO에 대한 다섯 종류의 AEBRP들의 돌연변이 억제효과는 일반적으로 약한 편이었으며, 특히 homocatechol-AEBRP는 TA98 균주에서 48%의 억제효과를 보였고 TA100 균주에서는 homocatechol-AEBRP와 hydroquinone-AEBRP가 46%에서 58% 정도의 억제효과를 나타내었다.