• 약학회지
• /
• 제28권1호
• /
• pp.53-59
• /
• 1984

Drug-metabolizing system which has the important role in drug metabolism is localized in smooth endoplasmic reticulum of hepatocytes and is composed of NADPH, NADPH-cytochrome $P_{450}$ reductase, cytochrome $P_{450}$ and others. It is well known that the enzyme system is induced by phenobarbital and methylcholanthrene. Lipid peroxidation is reaction of oxidative deterioration of polyunsaturated lipids. Formation of lipid peroxides in liver microsome has been found to produce degradation of phospholipid, which are major components of microsomal membrane. The relationship between the formation of lipid oxides and the activities of drug-metabolizing enzyme in the liver of rats was reported by several investigators. In this study the effect of riboflavin tetrabutylate, an antioxidant on lipid peroxidation, specially the relationship between lipid peroxidation and drug-metabolizing enzyme system was investigated. In addition the effect of vitamin A derivatives, such as retinoic acid and retinoid on the enzyme was also observed. Results are summarized as followings. 1) The pretretment with riboflavin tetrabutylate inhibited completely the lengthened sleeping time due to $CCl_{4}$ treatment. 2) The increase of TBA value was prevented by the pretreatment with riboflavin tetrabutylate. 3) The pretreatment with riboflavin tetrabutylate also prevented the decrease of drug-metabolizing enzyme caused by $CCl_{4}$. 4) Both retinoic acid and retinoid remarkably decreased the activity of aminopyrine demethylase. Pretreatment of riboflavin tetrabutylate, however, prevented inhibitory effect of retinoic acid on the enzyme activity.

• Corrosion Science and Technology
• /
• 제11권1호
• /
• pp.9-14
• /
• 2012

The formation of the Fe-Al inhibition layer in hot-dip galvanizing is a confusing issue for a long time. This study presents a characterization result on the inhibition layer formed on C-Mn-Cr and C-Mn-Si dual-phase steels after a short time galvanizing. The samples were annealed at $800^{\circ}C$ for 60 s in $N_{2}$-10% $H_{2}$ atmosphere with a dew point of $-30^{\circ}C$, and were then galvanized in a bath containing 0.2 %Al. X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) was employed for characterization. The TEM electron diffraction shows that only $Fe_{2}Al_{5}$ intermetallic phase was formed. No orientation relationship between the $Fe_{2}Al_{5}$ phase and the steel substrate could be identified. Two peaks of Al 2p photoelectrons, one from metallic aluminum and the other from $Al^{3+}$ ions, were detected in the inhibition layer, indicating that the layer is in fact a mixture of $Fe_{2}Al_{5}$ and $Al_{2}O_{3}$. TEM/EDS analysis verifies the existence of $Al_{2}O_{3}$ in the boundaries of $Fe_{2}Al_{5}$ grains. The nucleation of $Fe_{2}Al_{5}$ and the reduction of the surface oxide probably proceeded concurrently on galvanizing, and the residual oxides prohibited the heteroepitaxial growth of $Fe_{2}Al_{5}$.

• Applied Biological Chemistry
• /
• 제20권1호
• /
• pp.117-122
• /
• 1977

담배에 질산염을 청가하면 질소화합물이 증가되므로 질산염의 대체물(代替物)을 개발(開發)하기위한 실험을 한 결과 다음과 같은 결론을 얻었다. 여러가지 첨가제 중에서 $0.6{\sim}1%$의 시트르산나트륨을 첨가하는 것이 연소성 및 Tar, Nicotine의 감소효과(減少效果)가 가장 양호했다. 특히 조연제첨가(助燃濟添加)에 따른 연소성(燃燒性)과 유해성분감소효과(有害成分減少效果) 및 열특성(熱特性)에 대(對)한 다음과 같은 결과를 얻었다. 1) 연소성이 좋으면 Tar, Nicotine, Bonzpyrene Phenols, NO, $NO_2E, 등의 유해성분이 감소됐다. 2) 단엽에 첨가(添加)된 질산염과 시트르산염의 시차열분석효과(示差熱分析效果)는 시트르산염 첨가시(時) L치(値)가 가장 적고 H치(値)가 가장 컸다. 3) 순수한 질산염과 시트르산염의 시차열분석(示差熱分析)에서 전자는 발열반응(發熱反應)이 없는데 후자는 발열반응(發熱反應)이 있었다. 4) $0.6{\sim}1%$의 시트르산나트륨 첨가시(時)에 Zone A에서는 Tar생성량이 많았고 Zone B에서는 Tar 생성량이 가장 적었다. 또한 이들 담배의 연기에서는 Tar, Nicotine, Phenols, Nitrogen oxides, Benzpyrene의 함량(含量)이 적었으며 연소성이 향상되었다.

• 한국분말재료학회지
• /
• 제20권3호
• /
• pp.197-202
• /
• 2013

A novel route to prepare Nd-Fe-B magnetic particles by utilizing both spray drying and reduction/diffusion processes was investigated in this study. Precursors were prepared by spray drying method using the aqueous solutions containing Nd salt, Fe salt and boric acid with stoichiometric ratios. Precursor particles could be obtained with various sizes from 2 to $10{\mu}m$ by controlling concentrations of the solutions and the average size of $2{\mu}m$ of precursors were selected for further steps. After heat treatment of precursors in air, Nd and Fe oxides were formed through desalting procedure, followed by reduction processes in Hydrogen ($H_2$) atmosphere and with Calcium (Ca) granules in Argon (Ar) successively. Moreover, diffusion between Nd and Fe occurred during Ca reduction and $Nd_2Fe_{14}B$ particles were formed. With Ca amount added to particles after $H_2$ reduction, intrinsic coercivity was changed from 1 to 10 kOe. In order to remove and leach CaO and residual Ca, de-ionized water and dilute acid were used. Acidic solutions were more effective to eliminate impurities, but Fe and Nd were dissolved out from the particles. Finally, $Nd_2Fe_{14}B$ magnetic particles were synthesized after washing in de-ionized water with a mean size of $2{\mu}m$ and their maximum energy product showed 9.23 MGOe.

• Applied Biological Chemistry
• /
• 제21권2호
• /
• pp.131-136
• /
• 1978

The effects of liquid sugar and sucrose on several characteristic of tobacco leaves, there combustibility and harmful compound in smoke were examined. results obtained were as follows. 1) Nicotine and total nitrogen content of tobacco leaves were reduced by sugars added to tobacco. 2) Nicotine and tar transfered to smoke were reduced by 4% sugars added to burley tobacco but not reduced by sugars added to hicks. 3) pH of smoke was reduced by sugars added but pH of tobacco shreds not reduced by sugars added. 4) The filling capacity and combustibility (S. B. R.) of tobacco shreds were increased by sugars treated. 5) Nitrogen oxides transfered to smoke was reduce by sugars treated but phenols transfered was not reduce by sugar treated. 6) The capacities of moisture absorption and retention was increased by sugars treated.

• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 2003년도 총회 및 춘계학술발표회
• /
• pp.393-396
• /
• 2003

Soil contains the several kinds of metal oxides. Magnetite in soil may contribute the generation of secondary waste during the decontamination of soil by citric acid. Dissolution of magnetite powders by citric acid was investigated in the pH range between 2.0 and 5.0. The dissolution behaviour of magnetite was well described by the equation, A[1 - $e^{-B(x-c)}$]. The parameters of the equation were optimized by the iteration method, and the physical meaning of each parameter was explained. Concentration of each of the dissociated chemical species of citric acid was calculated using the ionization constants. The dissolution reaction was explained by the concentration of the dissociated chemical species of citric acid.d.

• 한국자기학회:학술대회 개요집
• /
• 한국자기학회 2008년도 Asian Magnetics Conference
• /
• pp.117.2-117.2
• /
• 2008

• 한국재료학회지
• /
• 제29권6호
• /
• pp.363-370
• /
• 2019

The recent development of information and communication technologies brings new changes to automobile traffic systems. The most typical example is the advancement of dedicated short range communication(DSRC). DSRC mainly consists of an intelligent transportation system(ITS), an electronic toll collection system(ETCS) and an advanced traveler information system(ATIS). These wireless communications often cause unnecessary electromagnetic waves, and these electromagnetic waves, in turn, cause frequent system malfunction. To solve this problem, an absorber of electromagnetic waves is suggested. In this research, various materials, such as powdered metal and iron oxides, are used to test the possibility for an effective absorption of the unnecessary electromagnetic waves. The various metal powders are made into a thin sheet form by compositing through processing. The electromagnetic characteristics(complex permittivity, complex permeability) of the fabricated sheet are measured. As a result, we achieve -6.5 dB at 940 MHz(77.6 % absorption rate) with a 1.0 mm-thickness electromagnet wave absorber, and -9.5 dB at 940 MHz(88.8 % absorption rate) with a 2.0 mm-thickness absorber.

• 한국세라믹학회지
• /
• 제49권2호
• /
• pp.191-196
• /
• 2012

In this study, tin phosphate glass system($SnO_2-(1-x)P_2O_5-xB_2O_3$) that occur during the melting of the metal oxide inhibition of the oxidation reaction, and to reduce oxides of high melting temperature in the following three methods were melting. The first is the general way in the atmosphere, and the second by injecting $N_2$ gas under a neutral atmosphere, and finally in the air were melted by the addition of a reducing agent Melt in the atmosphere when the oxidation of the metal oxide is inhibited by low temperatures were melting. In addition, the deposition of crystals within glassy or inhibit devitrification phenomenon is also improved over 80% transmittance. This phenomenon, when the melting of glass, many of $Sn^{4+}$ ions are reduced to the $Sn^{2+}$ was forming oxides SnO, because it acts as a modifier oxide.

• Bulletin of the Korean Chemical Society
• /
• 제34권4호
• /
• pp.1137-1144
• /
• 2013

$TiO_2$ composites with seven different carbon materials (activated carbons, graphite, carbon fibers, single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene oxides, and reduced graphene oxides) that are virgin or treated with nitric acid are prepared through an evaporation method. The photocatalytic activities of the as-prepared samples are evaluated in terms of $H_2$ production from aqueous methanol solution (photo-catalytic reduction: PCR) and degradation of aqueous pollutants (phenol, methylene blue, and rhodamine B) (photocatalytic oxidation: PCO) under AM 1.5-light irradiation. Despite varying effects depending on the kinds of carbon materials and their surface treatment, composites typically show enhanced PCR activity with maximum 50 times higher $H_2$ production as compared to bare $TiO_2$. Conversely, the carbon-induced synergy effects on PCO activities are insignificant for all three substrates. Colorimetric quantification of hydroxyl radicals supports the absence of carbon effects. However, platinum deposition on the binary composites displays the enhanced effect on both PCR and PCO reactions. These differing effects of carbon materials on PCR and PCO reactions of $TiO_2$ are discussed in terms of physicochemical properties of carbon materials, coupling states of $TiO_2$/carbon composites, interfacial charge transfers. Various surface characterizations of composites (UV-Vis diffuse reflectance, SEM, FTIR, surface area, electrical conductivity, and photoluminescence) are performed to gain insight on their photocatalytic redox behaviors.