• The Korean Journal of Physiology
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• 제3권1호
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• pp.11-18
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• 1969

Tissue homogenates of 10 kinds of human cancer tissues were incubated in medium containing either one of $C^{14}-1,\; C^{14}-2,\;or\; C^{14}-3-lactate $ as a substrate in order to observe the oxidative pathway of lactate in cancer tissues. Lactate concentration in incubation medium was maintained at 50 mg%. At the end of incubation period, gas samples and incubation media were analyzed for total $CO_2$ production rates, radioactivities of respiratory $CO_2$, lactate uptake rates and pyruvate appearance rates. The following results were obtained. 1. Lactate uptake rates in all of cancer tissues examined were less than $2.5\;{\mu}M/hr/gm$ and much lower than those in normal tissues. 2. In the 10 kind of human cancer tissues, total $CO_2$ production rates were less than $10\;{\mu}M/hr/gm$, in all cases. These lower values impressed that oxidative metabolism in tumor tissues generally inhibited as compared with that in normal tissue. On the other hand, fractions of $CO_2$ derived from lactate to total $CO_2$ production rates were less than 15% except one case These facts showed that oxidation of lactate into $CO_2$ was greatly inhibited in tumor tissues. 3. Respiratory $CO_2$ yields from C-1 carbon of lactate in various cancer tissues were mean of 77.7% of total $CO_2$ yield from lactate and $CO_2$ yields from C-2 and C-3 carbon of lactate were mean of 9.1% and 12.6% respectively. These facts showed that carboxyl carbon of lactate oxidized more easily than ${\alpha}\;and\;{\beta}$ carbon of lactate. 4. In 10 kinds of cancer tissues, fractions of disappeared lacteate from media into $CO_2$ and pyruvate, which expressed as RLD $co_2$ and RLDpy respectively, were about 5% in except 3 cases and less than 3% except one case. These fact showed that almost of disappeared lactate from media were degraded into compounds other than $CO_2$ and pyruvate. From the above date, it was suggested that in the oxidative pathway of lactate in cancer tissues $CO_2$ was easily Produced from carboxyl carbon of lactate by oxidative decarboxylation as in the normal tissue, and further oxidation of 2 carbon unit via TCA cycle was inhibited.

• Korean Chemical Engineering Research
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• 제57권2호
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• pp.283-288
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• 2019

Catalytic removal of sulfur compounds from heavy naphtha (HN) was investigated using a combination of an oxidation process using hydrogen peroxide and an adsorption process using granulated activated carbon (GAC) and white eggshell (WES). This study investigated the impact of changing several operating parameters on the desulfurization efficiency. Specifically, the volume ratio of $H_2O_2$ to HN (0.01~0.05), agitation speed ($U_{speed}$) of the water bath shaker ($100-500{\pm}1rpm$), pH of sulfur solution (1~5), amount of adsorbent (0.1~2.5 g), desulfurization temperature ($25{\sim}85{\pm}1^{\circ}C$) and contact time (10~180 minutes) were examined. The results indicate that the desulfurization efficiency resulting from catalytic and adsorption processes of GAC is better than that of WES for oxidation and removing sulfur compounds from HN due to its high surface area. The desulfurization efficiency depends strongly on all investigated operating parameters. The maximum removal efficiency of GAC and WES achieved by this study was 86 and 65, respectively.

• Bulletin of the Korean Chemical Society
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• 제29권5호
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• pp.988-992
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• 2008

A poly(methyl red) film-modified glassy carbon electrode (PMRE) was fabricated for determination of norfloxacin (NFX). The electrochemical behavior of NFX was investigated and a well-defined oxidation peak with high sensitivity was observed at the film electrode. PMRE greatly enhanced the oxidation peak current of NFX owing to the extraordinary properties of poly(methyl red) film. Based on this, a sensitive and simple voltammetric method was developed for measurement of NFX. A sensitive linear voltammetric response for NFX was obtained in the concentration range of $1\;{\times}\;10^{-6}\;-\;1\;{\times}\;10^{-4}$ mol/L and the detection limit was $1\;{\times}\;10^{-7}$ mol/L using linear sweep voltammetry (LSV). The proposed method possessed advantages such as low detection limit, fast response, low cost and simplicity. The practical application of this new analytical method was demonstrated with NFX pharmaceuticals.

• 한국표면공학회지
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• 제43권1호
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• pp.36-40
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• 2010

The SiO vapor that was generated from a mixture of Si and $SiO_2$ was reacted at $1350^{\circ}C$ for 2 h under vacuum with carbon nanofibers to produce SiC nanofibers having an average diameter of 100~200 nm. In order to understand the gas corrosion behavior, SiC nanofibers were exposed to air up to $1000^{\circ}C$. SiC oxidized to amorphous $SiO_2$, but its oxidation resistance was inferior unlike bulk SiC, because of high surface area of nanofibers. When SiC nanofibers were exposed to Ar-1% $SO_2$ atmosphere, SiC oxidized to amorphous $SiO_2$, without forming $SiS_2$, owing to the thermodynamic stability of $SiO_2$.

• Carbon letters
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• 제14권2호
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• pp.117-120
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• 2013

In this study, an electro-catalyst of Pt nanoparticles supported by polypyrrole-functionalized graphene (Pt/PPy-reduced graphene oxide [RGO]) is reported. The Pt nanoparticles are deposited on the PPy-RGO composite by chemical reduction of H2PtCl6 using NaBH4. The presence of graphene (RGO) caused higher activity. This might have been due to increased electro-chemically accessible surface areas, increased electronic conductivity, and easier charge-transfer at polymer-electrolyte interfaces, allowing higher dispersion and utilization of the deposited Pt nano-particles. Microstructure, morphology and crystallinity of the synthesized materials were investigated using X-ray diffraction and transmission electron microscopy. The results showed successful deposition of Pt nano-particles, with crystallite size of about 2.7 nm, on the PPy-RGO support film. Catalytic activity for methanol electro-oxidation in fuel cells was investigated using cyclic voltammetry. The fundamental electrochemical test results indicated that the electro-catalytic activity, for methanol oxidation, of the Pt/PPy-RGO combination was much better than for commercial catalyst.

• 한국해양바이오학회지
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• 제2권1호
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• pp.55-59
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• 2007

The oil and concentrated protein powder from squid viscera was extracted and recovered by a semi-batch supercritical carbon dioxide ($SCO_2$) extraction system and the degree of oxidation in the extracted oil was measured in order to compare with extracted oils using organic solvents. The degree of storage in treated squid viscera by $SCO_2$ extraction was measured in order to compare with untreated squid viscera. As results obtained, it was found that the auto-oxidation of the oils using $SCO_2$ extraction occurred very slowly compared to the oils by organic solvent extraction. And the treated squid viscera by $SCO_2$ extraction was reached the point of initial rottenness slowly than untreated squid viscera.

• 한국대기환경학회지
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• 제20권4호
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• pp.515-521
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• 2004

The catalytic oxidation of volatile organic compounds (methanol. acetaldehyde) has been characterized using the copper phthalocyanine catalyst in a fixed bed flow reactor under atmospheric pressure. The catalytic activity for pretreatment conditions was examined by this reaction system. The catalytic activity was ordered as follows: metal free-PC＜Cu ($\alpha$)-PC＜Cu ($\beta$)-PC The formaldehyde, carbon monoxide as a partial oxidation product of methanol and acetaldehyde over Cu ($\alpha$)-PC catalyst were detected and the conversions of methanol and acetaldehyde were accomplished above 95% over Cu ($\alpha$) -PC, Cu ($\beta$) - PC catalyst at 35$0^{\circ}C$. The pretreated metal free -PC, Cu($\alpha$)-PC, Cu($\beta$)-PC catalysts have been characterised by TGA, EA and XRD analysis. The catalytic activity pretreated with air and $CH_3$OH mixture (P-4) or air only (P-5) was very excellent. XRD and EA results showed that Cu($\alpha$)-PC, Cu($\beta$)-PC were destroyed an(1 new metal oxide such as CuO were formed.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1999년도 제30회 추계학술대회
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• pp.63-70
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• 1999

Surface hardening of plain carbon steel (SM45C) by Laser are usually much finer and stronger than those of the base metals. The present study was under taken to investigate the wear resistance and a processing parameters such as, power density, pulse width, defocusing distance, and molten depth for surface modification of plain carbon steel. The wear test was carried out under experimental condition using the wear test device, and in which the annular surfaces of wear test specimens as well as mating specimen of alumina ceramics($Al_2O_3$) was rubbed in dry sliding condition. It is shown that molten depth and width depend on defocusing distance. The wear loss on variation of sliding speed was much in lower speed range below 0.2m/sec and in higher speed range above 0.7m/sec, but wear loss was little in intermediate speed range. It depends on oxidation speed and wear speed.

• Transactions on Electrical and Electronic Materials
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• 제10권6호
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• pp.217-221
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• 2009

The use of the carbon nanotube (CNT) is superior to the general powder state materials in their thermal and chemical properties. Because its ratio of diameter to length (aspect ratio) is very large, it is known to be a type of ideal nano-reinforcement material. Based on this advantage, the existing carbon black of the semiconductive shield materials used in power cables can acquire excellent properties by the use of a small amount of CNTs. Therefore, we fabricated specimens using a solution mixing method. We investigated the thermal properties of the CNT, such as its storage modulus, loss modulus, and its tan delta using a dynamic mechanical analysis 2980. We found that a high thermal resistance level is demonstrated by using a small amount of CNTs. We also investigated the chemical properties of the CNT, such as the oxidation reaction by using Fourier transform infrared spectroscopy (FT-IR) made by Travel IR. In the case of the FT-IR tests, we searched for some degree of oxidation by detecting the carboxyl group (C=O). The results confirm a tendency for a high cross-linking density in a new network in which the CNTs situated between the carbon black constituent molecules show a bond using similar constructive properties.

• Asian Journal of Atmospheric Environment
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• 제6권3호
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• pp.137-146
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• 2012

Poor indoor air quality is now worldwide concern due to its adverse impacts on our health and environment. Moreover, these impacts carry a significant burden to the economy. Various technical approaches (e.g., biological, activated carbon fiber (ACF), photocatlytic oxidation (PCO), etc.) have gained popularity in controlling indoor volatile organic compounds (VOCs). This is because removing indoor VOC sources or increasing ventilation rates is often not feasible or economical. This review provides an overview of the various air purification technologies used widely to improve indoor air quality. Although most of these technologies are very useful to remove indoor VOCs, there is no single fully satisfactory method due to their diversity and presence at the low concentration. To achieve technical innovations and the development of specific testing protocols, one should possess a better knowledge on the mechanisms of substrate uptake at VOC concentrations.