• Journal of Food Hygiene and Safety
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• v.32 no.6
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• pp.447-454
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• 2017

A new amperometric biosensor has been developed for the detection of hydrogen peroxide ($H_2O_2$). The sensor was fabricated through the one-step deposition of a biocomposite layer onto a glassy carbon electrode at neutral pH. The biocomposite, as a $H_2O_2$ sensing element, was prepared by the electrochemical deposition of a homogeneous mixture of graphene oxide, aniline, and horseradish peroxidase. The experimental results clearly demonstrated of that the sensor possessed high electrocatalytic activity and responded to $H_2O_2$ with a stable and rapid manners. Scanning electron microscopy, cyclic voltammetry, and amperometry were performed to optimize the characteristics of the sensor and to evaluate its sensing chemistry. The sensor exhibited a linear response to $H_2O_2$ in the range of 10 to $500{\mu}M$ concentrations, and its detection limit was calculated to be $1.3{\mu}M$. The proposed sensing-chemistry strategy and the sensor format were simple, cost-effective, and feasible for analysis of "food-grade $H_2O_2$" in food samples.

• Korean Journal of Materials Research
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• v.32 no.1
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• pp.14-22
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• 2022

To improve light absorption ability in the visible light region and the efficiency of the charge transfer reaction, Pd nanoparticles decorated with reduced TiO₂ nanotube photocatalyst were synthesized. The reduced TiO₂ nanotube photocatalyst was fabricated by anodic oxidation of Ti plate, followed by an electrochemical reduction process using applied cathodic potential. For TiO₂ photocatalyst electrochemically reduced using an applied voltage of -1.3 V for 10 min, 38% of Ti⁴⁺ ions on TiO₂ surface were converted to Ti³⁺ ion. The formation of Ti³⁺ species leads to the decrease in the band gap energy, resulting in an increase in the light absorption ability in the visible range. To obtain better photocatalytic efficiency, Pd nanoparticles were decorated through photoreduction process on the surface of reduced TiO₂ nanotube photocatalyst (r10-TNT). The Pd nanoparticles decorated with reduced TiO₂ nanotube photocatalyst exhibited enhanced photocurrent response, and high efficiency and rate constant for aniline blue degradation; these were ascribed to the synergistic effect of the new electronic state of the TiO₂ band gap energy induced by formation of Ti³⁺ species on TiO₂, and by improvement of the charge transfer reaction.

• Journal of Food Hygiene and Safety
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• v.35 no.4
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• pp.291-303
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• 2020

Marine organism-derived toxins have negative effects not only on human health but also in aquaculture, fisheries, and marine ecosystems. However, traditional analytical methods are insufficient in preventing this threat. In this paper, we reviewed new rapid methods of toxin detection, which have been improved by adopting diverse types of nanomaterials and technologies. Moreover, we herein describe the main strategies for toxin detection and their related sensing performance. Notably, to popularize and commercialize these newly developed technologies, simplifying the process of pre-treating real samples real samples is very important. As part of these efforts, numerous studies have reported pretreatment methods based on the antibody-immobilized magnetic nanoparticles, and some cases have applied nanoparticles to enhance the sensing performance by utilizing the intrinsic catalytic activity. Furthermore, some reports have introduced fluorescent nanoparticles, such as quantum dots, to represent the lower detection limits of conventional enzyme-based colorimetric methods and lateral flow assays. Some studies using electrochemical measurements based on aptamer-nanoparticle complexes have also been announced. In addition, as the response to new toxins generated by changes in the marine environment is still lacking, further research on diagnostic and detection is also greatly needed for these kinds of marine toxins and their derivatives.

• Korean Journal of Materials Research
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• v.3 no.6
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• pp.632-637
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• 1993

The optical properties and electrochromism of amorphous $WO_3$ thin films were studied. $WO_3$ thin films with thickness of 3000$\AA$~6000$\AA$ were deposited by vacuum evaporat.ion. All these films were transparent and found to be amorphous in structure by X-ray diffraction analysis and the visible wave length refractive indices were found to be between 1.9 and 2.1 and the optical energey gap to be 3.25 eV. Electrochromic devices were made consisting of IT0 transparent electrode, $WO_3$ thin films, $LiCIO_4$- propylene carbonate and Pt counter electrode. In terms of their operation, the amorphous $WO_3$ films were colored blue by a double injection of electrons from the transparent electrode and lithium ions from the $LiCIO_4$-propylene carbonate organic electrolyte and made colorless by electrochemical oxidation reaction. The electrochromic properties of $WO_3$ thin films including coloration and bleaching, optical density and response time were all found to be strongly dependent on the film deposition condition, electrolyte concentration, sheet resistance of the transparent electrode and applied voltage.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.87-87
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• 2010

Photoelectrochemical (PEC) systems are promising methods of producing H2 gas using solar energy in an aqueous solution. The photoelectrochemical properties of numerous metal oxides have been studied. Among them, the PEC systems based on TiO2 have been extensively studied. However, the drawback of a PEC system with TiO2 is that only ultraviolet (UV) light can be absorbed because of its large band gap (3.2 - 3.4 eV). Two approaches have been introduced in order to use PEC cells in the visible light region. The first method includes doping impurities, such as nitrogen, into TiO2, and this technique has been extensively studied in an attempt to narrow the band gap. In comparison, research on the second method, which includes visible light water splitting in molecular photosystems, has been slow. Mallouk et al. recently developed electrochemical water-splitting cells using the Ru(II) complex as the visible light photosensitizer. the dye-sensitized PEC cell consisted of a dye-sensitized TiO2 layer, a Pt counter electrode, and an aqueous solution between them. Under a visible light (< 3 eV) illumination, only the dye molecule absorbed the light and became excited because TiO2 had the wide band gap. The light absorption of the dye was followed by the transfer of an electron from the excited state (S*) of the dye to the conduction band (CB) of TiO2 and its subsequent transfer to the transparent conducting oxide (TCO). The electrons moved through the wire to the Pt, where the water reduction (or H2 evolution) occurred. The oxidized dye molecules caused the water oxidation because their HOMO level was below the H2O/O2 level. Organic dyes have been developed as metal-free alternatives to the Ru(II) complexes because of their tunable optical and electronic properties and low-cost manufacturing. Recently, organic dye molecules containing multi-branched, multi-anchoring groups have received a great deal of interest. In this work, tri-branched tri-anchoring organic dyes (Dye 2) were designed and applied to visible light water-splitting cells based on dye-sensitized TiO2 electrodes. Dye 2 had a molecular structure containing one donor (D) and three acceptor (A) groups, and each ended with an anchoring functionality. In comparison, mono-anchoring dyes (Dye 1) were also synthesized. The PEC response of the Dye 2-sensitized TiO2 film was much better than the Dye 1-sensitized or unsensitized TiO2 films.

• Analytical Science and Technology
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• v.10 no.3
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• pp.187-195
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• 1997

Chemically modified electrodes(CMEs) for Ag(I) were constructed by incoporating 1,5,9,13-tetrathiacyclohexadecane([16]-ane-$S_4$) with a conventional carbon-paste mixture composed of graphite powder and nujol oil. Ag(I) ion was chemically deposited onto the surface of the modified electrode with [16]-ane-$S_4$ by immersion of the electrode in the acetate buffer solution(pH=4.5) containing $5.0{\times}10^{-4}M$ Ag(I) ion. And then the electrode deposited with Ag(I) was reduced at -0.3V vs. S.C.E. Well-defined stripping voltammetric peaks could be obtained by scanning the potential to the positive direction. The CME surface was regenerated with exposure to 0.1M $HNO_3$ solution and was reused for the determination of Ag(I) ion. When deposition/measurement/regeneration cycles were 10 times, the response could be reproduced with relative standard deviation of 6.08%. In case of differential pulse stripping voltammetry, the calibration curve for Ag(I) was linear over the range of $5.0{\times}10^{-7}{\sim}1.5{\times}10^{-6}M$. And the detection limit was $2.0{\times}10^{-7}M$. Various ions such as Cd(II), Ni(II), Pb(II), Zn(II), Mn(II), Mg(II), EDTA, and oxalate(II) did not influence the determination of Ag(I) ion, except Cu(II) ion.

• Journal of the Korean GEO-environmental Society
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• v.18 no.4
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• pp.23-29
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• 2017

As the Enforcement Ordinance of Environmental Policy Act was revised in 2013, Total Organic Carbon (TOC) was added as an indicative parameter for organic matter in Water and Aquatic Ecosystem Environmental Criteria. Under these imminent circumstances, a regulatory standard is needed to achieve the proposed TOC limitation control water quality from the STP (Sewage Treatment Plant). In this study, a electrolysis utilizing the electrochemical reaction was investigated in lab-scale experiments for the treatment of TOC in sewage effluent. TOC reduction by a electrolysis was investigated response surface methodology using the Box-Begnken methods were applied to the experimental results. A central composite design was used to investigate the effects of the independent variables of electrode space ($x_1$), current density ($x_2$) and electrolyte concentration ($x_3$) on the dependent variables removal efficiency of TOC (y). The optimal conditions for electrolysis were determined: electrode space, current density and electrolyte concentration were 50 mm, $10.3mA/cm^2$ and 0.1M, respectively. Statistical results showed the order of significance of the independent variables to be electrode space > current density > electrolyte concentration.

• Polymer(Korea)
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• v.29 no.4
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• pp.403-407
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• 2005

In this work, the solid polymer electrolyte (SPE) composites, which are composed of poly(ethylene oxide) (PEO), mesoporous mobil crystalline material-41 (MCM-41), and lithium salt, are prepared in order to investigate the influence of MCM-41 contents on the ionic conductivity of the composites. The crystallinity of the SPE composites was evaluated using differential scanning calorimeter (DSC) and X-ray diffraction (XRD). The ionic conductivity of the SPE composites was measured by the frequency response analyzer (FRA). As a result, the addition of MCM-41 into the polymeric mixture prohibited the growth of PEO crystalline domain due to the mesoporous structures of the MCM-41. The $P(EO)_{16}LiClO_4$/MCM-41 electrolytes show an increased ion conductivity as a function of MCM-41 content up to 8 $wt\%$ and a slightly decreased conductivity over 8 $wt\%$. These ion conductivity characteristics are dependent on a change of polymer crystallinity in the presence of MCM-41 system.

• Journal of Preventive Medicine and Public Health
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• v.27 no.1 s.45
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• pp.84-106
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• 1994

Hyperbaric oxygen (HBO) therapy for carbon monoxide (CO) poisoning eventually inducing the hypoxia-reoxygenation condition, may produce oxygen free radicals, which forms 8-hydroxydeoxyguanosine (8-OH-dG) by attacking C-8 position of deoxyguanosine (dG) in DNA. Effects of oxygen partial pressure or duration of HBO therapy with or without CO poisoning on the tissue 8-OH-dG formation were investigated. Male Sprague-Dawley rats were grouped and exposed to air (control group), 4000 ppm of CO for 10 to 30 minutes (CO only group), air for 30 minutes after 30 minute exposure to 4000 ppm of CO(CO-air exposure group), HBO after 30 minute exposure to 4000 ppm of CO(CO-HBO group), or HBO therapy fo. $10{\sim}120$ minutes(HBO only group). The 8-OH-4G concentrations in the brain and the lung tissues were measured with high performance liquid chromatography and electrochemical detector (ECD). Average concentrations of the 8-OH-dG of each group were statistically compared. In the brain tissues, 8-OH-dG concentrations of the CO only group, the CO-air exposure group, and the CO-HBO group did not significantly differ from those of the control group. Similar insignificance was also found between the CO-HBO group and the HBO only groups. No appreciable dose-response relationship was observed between the 8-OH-dG concentration and the oxygen partial pressure or the duration of HBO. However, the 8-OH-dG concentrations of the 30 minute CO only group were higher than those of the CO-air exposure group (p-value<0.05). In the lung tissues, there were no significant differences between the 8-OH-dG concentrations of the control group and those of the CO only group, the CO-air exposure group, and the CO-HBO group. However, mean 8-OH-dG concentration of the CO-air exposure group was significantly higher than that of the CO only group under the same CO exposure condition(p-value<0.05). With the duration of CO exposure, the 8-OH-dG concentrations of the lung tissues decreased significantly (p-value<0.05). The concentrations of 8-OH-dG in the lung tissues proportionally increased with the duration of HBO, but no such relation was observed with the oxygen partial pressure. These results suggest that the brain may be more resistant to oxygen free radicals as compared with the lungs, and that oxygen toxicity following HBO may be affected by factors other than oxygen free radicals.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.3
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• pp.212-218
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• 2020

When Radiofrequency energy is applied to the human body, the vibration width is very short. Therefore, the electrolyte burn generated when using the direct current does not occur. Ion molecules, polarized molecules, etc., vibrate more than 40,000 times per second, converting them into frictional heat to generate deep heat. The blood flow of capillaries increases 4-5 times more than at rest, increasing the supply of oxygen, nutrients, antibodies, and white blood cells. In addition, the electrochemical reaction does not occur because the vibration width and the pulsation period are very short. It is a physical factor treatment method that does not stimulate the sensory nerves and motor nerves. In this study, an isotonic exercise is performed in a young normal adult using a Radiofrequency pain treatment device. The purpose of this study is to integrate rehabilitation therapy by measuring electromyography data during isotonic exercise and confirming the effect on changes in motor neuron response. The EMG data generated when isotonic exercise of the forearm biceps muscle and the EMG data measured after the use of a Radiofrequency pain treatment device after exercise were RMS, respectively, and verified through t-test. It was confirmed that there was a significant difference in both men and women because the t-value was smaller than the significance level p (<.05).