• Transactions on Electrical and Electronic Materials
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• v.2 no.2
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• pp.21-25
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• 2001

This paper presents the effect of pyrazine on tetramethylammonium hydroxide (TMAH):isopropyl alcohol (IPA) single-crystal silicon anisotropic etching properties. With the addition of IPA to TMAH solutions, etching characteristics are exhibited an improvement in flatness on the etching front and a reduction in undercutting, but the etch rate on (100) silicon is decreased. The (100) silicon etch rate is improved by the addition of pyrazine. An etch rate on (100) silicon of 0.8 ${\mu}{\textrm}{m}$/min, which is faster by 13% than a 20 wt.% solution of pure TMAH, is obtained using 20 wt.% TMAH: 0.5 g/100 ml pyrazine solutions, but the etch rate on (100) silicon is decreased when more pyrazine is added. With the addition of pyrazine to a 25 wt.% TMAH solution, variations in flatness on the etching front are not observed and the undercutting ratio is reduced by 30~50%. These results indicate that anisotropic etching technology using TMAH:IPA:pyrazine solutions provides a powerful and versatile method for realizing of microelectromechanical systems.

• Journal of Sensor Science and Technology
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• v.7 no.6
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• pp.426-431
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• 1998

This paper describes electrochemical etch-stop characteristics in THAH/IPA/pyrazine solution. I-V curves of n- and p-type Si in THAH/IPA/pyrazine solution were obtained. OCP(Open Circuit Potential) and PP (Passivation Potential) of p-type Si were -1.2 V and 0.1 V, and of n-type Si were -1.3 V and -0.2 V, respectively. Both n- and p-type Si, etching rates were abruptly decreased at potentials anodic to the PP. The etch-stop characteristics in THAH/IPA/pyrazine solution were observed. Since accurate etching stop occurs at pn junction, Si diaphragms having thickness of epi-layer were fabricated. Etching rate is highest at optimum etching condition, TMAH 25wt.%/IPA 17vol.%/pyrazine 0.1g/100ml. thus the elapsed time of etch-stop was reduced.

• The Korean Journal of Pharmacology
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• v.29 no.2
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• pp.275-282
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• 1993

Liver microsomal epoxide hydrolase (mEH) is active in the detoxification of epoxide-containing reactive intermediate. Previous studies in this laboratory have shown that thiazole and pyrazine are efficacious inducers of mEH in rats with large increases in mEH mRNA levels (Carcinogensis, Kim et al, 1993). mEH was purified to electrophoretic homogeneity from thiazole-induced rat hepatic microsomes using DEAE-cellulose column chromatography whereas another protein $({\sim}43\;kDa)$ was co-purified with mEH from pyrazine-induced rat hepatic micrsomes (200 mg/kg body weight/day, ip, 3d). The antibody raised from a rabbit against mEH protein purified from thiazole-induced rat hepatic microsomes appeared to specifically recognize mEH protein in rat hepatic microsomes, as assessed by immunoblotting analysis. Immunoblotting analyses revealed a 10- and 7-fold increase in mEH levels in the hepatic microsomes isolated from thiazole- and pyrazine-treated rats, respectively. Moreover, immunoblotting analysis showed cross-reactivity of the mEH antibody with a 43 kDa protein in pyrazine-induced rat hepatic microsomes and with co-purified 43 kDa protein in purified fractions. The ratio between the 43 kDa protein and mEH in pyrazine-induced rat microsomes or in purified fractions was ${\sim}1$ to 15. N-terminal amino acid sequence analysis of both purified rat mEH and 43 kDa protein revealed that 10 out of 12 amino acids in N-terminus of the 43 kDa protein were identical with the mEH sequence with two amino acid residues of the 43 kDa protein undetermined. Either thiazole or pyrazine treatment, however, failed to increase the levels of mEH protein in rabbits while pyrazine caused elevation of the 43 kDa protein in this species, as determined by irnrnunoblotting analysis. These results demonstrated that treatment of rats with either thiazole or pyrazine causes elevation in hepatic mEH expiession whereas pyrazine treatment results in induction of another mEH-related 43 kDa protein and that a distinct species difference exists between rats and rabbits in the induction of mEH by these xenobiotics.

• The Korean Journal of Food And Nutrition
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• v.20 no.1
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• pp.9-13
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• 2007

In this study, sesame oils and sesame meals(A, B) were obtained from roasted sesame at $200^{\circ}C$ and $220^{\circ}C$, respectively. The total volatile component(VC) contents of these samples(A, B) were as follows : The sesame oils had 1,397.1 ppm and 1,518.8 ppm, and the sesame meals had 663.2 ppm and 775.3 ppm for samples A and B, respectively : sesame flavor was16,507.9 ppm, The major VCs in the sesame oils were pentane, 2-butanone, pyrazine, methylpyrazine, 2,5- and 2,6-dimethyl pyrazine, furfuryl alcohol, guaiacol and 4-vinylguaiacol. The pyrazine contents of the seasame oils were 834.4 ppm and 816.4 ppm for samples A and B, respectively. The major VCs in the sesame meals were 2-butanone, hexanal, pyrazine, methyl pyrazine, 2,6-dimethyl pyrazine, furfuryl alcohol, and so forth. For artificial sesame flavor, the total VC content was 16,507.9 ppm, and the major VCs were 2-butanone, guaiacol, and 4-vinylguaiacol. Approximately 35.02% of the total VC content of sesame flavor was composed of 2-butanone, guaiacol, and 4-vinylguaiacol, and these constituted more than 1,000 ppm of its total VC content.

• Journal of the Korean Society of Tobacco Science
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• v.19 no.2
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• pp.151-158
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• 1997

Burley leaf tobacco extracts has been heated at loot for 2 hours and changes in non-volatile fructosazines and volatile components were investigated. Major changes for the heat treatment with corn syrup of burley leaf tobacco extracts were as follows, increases in the contents of 2,5-deoxyfructosazine and 2,5-fructosazine that is produce for the heating reaction of sugar and ammonia, production of pyraEine compounds, such as 2,6-dimethyl pyrazine,2,4-dimethyl pyrazine, ethrnyl pyrazine, methylethyl pyraxine, trimethyl pyrazine, 2-ethenyl-5-methyl pyrazine, 2-acetyl parazine and 2-acetyl-3-methyl pyrazine, increases in the content of furfuryl alcohol derived from sugar degrad ation, production of 2,5-dimethyl-4-hydroxy-3(2H)-furanone and 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one derived from thermal degradation of Amadori compounds.

• Proceedings of the EASDL Conference
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• 2004.10a
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• pp.73-92
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• 2004

참기름은 높은 온도로 볶아 짜는 공정을 통해 제조되는데 이때 참깨의 성분 중 당과 단백질에 의한 Maillard 반응에 의해 향기성분인 pyrazine 화합물과 갈샐물질이 생성된다. 참깨의 볶는 방법, 온도 및 시간은 참기름의 맛과 향기에 중요한 인자가 될 수 있고 또한 참기름에 함유되어 있는 갈색물질과 향기성분인 pyrazine류가 생리활성을 나타낼 수 있는 가능성이 제기되어 본 연구에서는 참기름으로 부터 갈색화 관련 물질을 용매별로 분류하여 tyrosinase 저해 효과와 항상화 효과를 측정였고 pyrazine 유도체들의 혈소판 응집에 미치는 효과를 측정하였다. 갈색도가 높은 butanol, methanol 에서 농도 의존적으로 높은 tyrosinase 저해효과를 보였다. 또한 각종 radical 소거능을 측정한 결과 butanol 에서 높은 소거능을 보였다. 향기 성분에 다량 함유되어 있는 Pyrazine 유도체가 collagen 에 의해 유도된 혈소판 응집억제능을 측정한 결과 -methyl의 결합수가 많을수록 (2,3,5-trimethylpyrazine>2,5-dimethylpyrazine>pyrazine) 농도 의존적으로 높은 응집 억제효과를 나타내었다. 이상의 결과, 참기름 가공 공정에서 생성되는 갈색화관련 물질과 향기 성분인 pyrazine 유도체는 생리활성을 나타내는 물질임이 확인되어 기능성 식품에 다양하게 활용되기를 기대한다.

• Korean Journal of Food Science and Technology
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• v.7 no.1
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• pp.15-21
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• 1975

Soong-Neung is a Korean traditional beverage served after meals and is made from cooked and roasted rice produced on the bottom of the container during the rice cooking process. The volatiles from the extract of cooked and roasted rice were separated into pyrazine and carbonyl fractions and qualitatively investigated. The pyrazine fraction was characterized by gas chromatography and combined gas chromatography-mass spectrometry and five pyrazines were positively identified. Pyrazine compounds identified are 2-methylpyrazine, 2,3-dimethylpyrazine, 2,5-dimethylpyrazine, 2-ethyl-5-methylpyrazine and 2-ethyl-3-methylpyrazine. Carbonyls were converted to their 2,4-dinitrophenylhydrazones and identified by gas chromatography, combined gas chromatography-mass spectrometry and thin layer chromatography. Acetaldehyde, propionaldehyde, iso-butyraldehyde and iso-valeraldehyde were positively identified in the carbonyl compounds. The aroma of the fractions indentified as 2,3-dimethylpyrazine and 2,5-dimethylpyrazine had a nut-like or roasted cereal-like flavor, which is one of the characteristic flavors of Soong-Neung.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.423-426
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• 1998

Piezoresistive pressure sensors have fabricated using electrochemical etch-stop technique. Si diaphragm having thickness of n-epi. layer was fabricated and used to detect pressure range from 0 to 1 kg/$\textrm{cm}^2$. Piezoresistors were diffused 3${\times}$10$\^$18/ cm$\^$-3/ and placed at diaphragm edge for maximum pressure detection. The characteristics of electrochemical etch-stop in TMAH/lPA/pyrazine solution were also discussed. I-V curves of n and p-type Si in TMAH/lPA/pyrazine solution were obtained. Etching rate is highest at optimum etching condition, TMAH 25wt.%/IPA 17vo1.%/pyrazine 0.1/100m1, thus the elapsed time of etch-stop was reduced.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05b
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• pp.7-12
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• 2000

This paper presents the electrochemical etch-stop characteristics of single-crystal silicon in a tetramethyl ammonium hydroxide(TMAH):isopropyl alcohol(IPA):pyrazine solution. Addition of pyrazine to a TMAH:IPA etchant increases the etch-rate of (100) silicon, thus the elapsed time for etch-stop was shortened. The current-voltage (I-V) characteristics of n- and p-type silicon in a TMAH:IPA:pyrazine solution were obtained, respectively. Open circuit potential(OCP) and passivation potential(PP) of n- and p-type silicon, respectively, were obtained and applied potential was selected between n- and p-type silicon PP. The electrochemical etch-stop is applied to the fabrication of 801 microdiaphragms having $20{\mu}m$ thickness on a 5-inch silicon wafer. The averge thicknesses of 801 microdiaphragms fabricated on the one wafer were $20.03{\mu}m$ and standard deviation was ${\pm}0.26{\mu}m$. The silicon surface of the etch-stopped microdiaphragm was extremely flat without noticeable taper or other nonuniformities. The benefits of the electrochemical etch-stop in a TMAH:IPA:pyrazine solution become apparent when reproducibility in the microdiaphragm thickness for mass production is considered. These results indicate that the electrochemical etch-stop in a TMAH:IPA:pyrazine solution provides a powerful and versatile alternative process for fabricating high-yield silicon microdiaphragms.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.3
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• pp.384-388
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• 2000

본 연구는 cocoa mass를 마이크로파 roasting하여 그 향기성분의 변화를 pyrazine류를 중심으로 살펴보는 한편 상법으로 roasting한 경우와 비교하고자 하였다. 마이크로파 roasting은 110,120,130,140,15$0^{\circ}C$의 온도에서 20분 및 30분 동안 행하였고 상법의 경우는 14$0^{\circ}C$에서 30분간 roasting하였다. Roasting한 시료를 연속수증기증류추출법으로 추출하고 농축한 후 GC와 GC/MS로 향기 성분을 분석하였다. 마이크로파 roasting의 경우 5분만에 14$0^{\circ}C$에 도달한 후 그 온도를 잘 유지하였으나, 상법의 경우 25분이 경과되어서야 14$0^{\circ}C$에 도달되었다. Roasting 한 시료의 향기성분으로 2,6-dimethyl pyrazine, 2,3,5-trimethyl pyrazine, 2,3,5,6-teramethyl pyrazine, 5-methyl fufural, 2-methyl-6-propyl pyrazine 등이 확인되었다. Roasting 온도가 증가함에 따라 dimethyl-, trimethyl-, tetramethyl pyrazine류가 증가하였고, tetramethyl pyrazine은 15$0^{\circ}C$ 20분 roasting의 경우 현저하게 증가하였으나, 30분 동안 roasting한 경우 14$0^{\circ}C$에서 증가하였다가 15$0^{\circ}C$일 때는 감소하였다. 그러나 적정 roasting 지표인 di/tri, di/tetra pyrazine의 비율은 1 이하를 보임으로써 마이크로파 roasting이 cocoa mass의 향기 발현에는 부족한 것으로 나타났다.