• Bulletin of the Korean Chemical Society
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• 제12권4호
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• pp.434-437
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• 1991

Irradiation of 5-styryl-1,3-dimethyluracil (5-SDU) with 2,3-dimethyl-2-butene (DMB) gives a [4+2] cycloadduct which is converted into a [2+2] cycloadduct on the prolonged irradiation. Triplet sensitization, quenching, and external heavy atom effect on the [4+2] photocycloaddition reaction demonstrate the singlet pathway and salt effect excludes a radical ion pair precursor possibility. Polar solvents increase the reaction efficiency implying a polar exciplex involvement in the [4+2] photocycloaddition reaction. Inverse temperature dependence both on the reaction and DMB fluorescence quenching of 5-SDU indicates the presence of a singlet exciplex intermediate.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.289-289
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• 2017

The climate change impact has facilitated double cropping system on maize production in Korea. The objectives of this study were to investigate the chemical composition changes according to the sowing dates on double cropping in 8 dent type, 2 intermediate type, and 4 semiflint type of Korean maize (Zea mays L.) hybrids and evaluate its antioxidant characteristics. Fourteen maize hybrids were sown on April 5 and July 5 of 2015. The average crude protein contents in dent and semiflint type maize sown on April 5 were higher than those sown on July 5 (p<0.05). There was no significant difference in average of total amino acid contents in all types of maize according to the sowing dates. Major amino acid in maize hybrids were glutamic acid followed by proline, alanine, and aspartic acid, which has no significant difference according to the sowing dates. The average crude fat contents in semiflint and intermediate type maize sown on April 5 were higher than those sown on July 5 (p<0.05). The average composition of saturated fatty acid in dent type maize sown on April 5 was higher than those sown on July 5. However, the average unsaturated fatty acid composition showed the opposite result (p<0.05). Fatty acids were mainly composed of linoleic acid (C18:2) and oleic acid (C18:1) in maize hybrids. The average oleic acid percentage of dent and semiflint type maize sown on April 5 were higher than those sown on July 5, while the average linoleic acid was lower. The average amylose content of all types of maize sown on April 5 was higher than those sown on July 5. On the other hands, the average carotenoid contents had the opposite result (p<0.05). There were no significant differences in total average of polyphenol contents and DPPH and ABTS radical scavenging activities in all types of maize based on the sowing date. Total polyphenol contents had positive correlation with DPPH (r=0.33, p<0.01) and ABTS (r=0.50, p<0.0001) radical scavenging activities. In conclusion, the kernel composition affects maize quality. These data are useful for maize breeding program and cultivation and food processing industry.

• Journal of Gastric Cancer
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• 제24권2호
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• pp.172-184
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• 2024

Purpose: The original eCura system was designed to stratify the risk of lymph node metastasis (LNM) after endoscopic resection (ER) in patients with early gastric cancer (EGC). We assessed the effectiveness of a modified eCura system for reflecting the characteristics of undifferentiated-type (UD)-EGC. Materials and Methods: Six hundred thirty-four patients who underwent non-curative ER for UD-EGC and received either additional surgery (radical surgery group; n=270) or no further treatment (no additional treatment group; n=364) from 18 institutions between 2005 and 2015 were retrospectively included in this study. The eCuraU system assigned 1 point each for tumors >20 mm in size, ulceration, positive vertical margin, and submucosal invasion <500 ㎛; 2 points for submucosal invasion ≥500 ㎛; and 3 points for lymphovascular invasion. Results: LNM rates in the radical surgery group were 1.1%, 5.4%, and 13.3% for the low-(0-1 point), intermediate- (2-3 points), and high-risk (4-8 points), respectively (P-fortrend<0.001). The eCuraU system showed a significantly higher probability of identifying patients with LNM as high-risk than the eCura system (66.7% vs. 22.2%; McNemar P<0.001). In the no additional treatment group, overall survival (93.4%, 87.2%, and 67.6% at 5 years) and cancer-specific survival (99.6%, 98.9%, and 92.9% at 5 years) differed significantly among the low-, intermediate-, and high-risk categories, respectively (both P<0.001). In the high-risk category, surgery outperformed no treatment in terms of overall mortality (hazard ratio, 3.26; P=0.015). Conclusions: The eCuraU system stratified the risk of LNM in patients with UD-EGC after ER. It is strongly recommended that high-risk patients undergo additional surgery.

• 대한환경공학회지
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• 제27권6호
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• pp.567-572
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• 2005

본 연구에서는 용존공기부상법(DAF)을 이용한 정수처리 공정에 오존을 도입하기 위하여 실험실 규모의 실험이 수행되었다. 오존의 수처리 적용시 공정제어 인자로 활용할 수 있는 I.D, $k_c$, 오존-Ct 및 OH 라디칼-Ct 등에 대한 반응속도론적 연구를 실시하였다. 또한 원수, DAF 처리수 및 여과수에 대한 오존처리 실험을 실시하여 오존공정의 최적 위치 및 주입량을 도출하였다. 실험 결과 오존-Ct와 OH 라디칼-Ct는 DAF 처리수에서 가장 높게 측정되었으며, DAF 공정의 체류시간인 30분 이후에도 계속적으로 유지되었다. 또한 각 공정수에 대한 오존처리 실험을 실시한 결과, 중오존이 전 후오존에 비해 높은 효율을 기대할 수 있을 것으로 나타났으며, 최적 오존주입농도는 $1{\sim}2\;mg/L$로 판단되었다. 이러한 결과로부터 중오존 / DAF(ozoflotation) 공정 도입을 위한 기초자료로서 활용하고자 하였다.

• 대한기계학회논문집B
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• 제29권2호
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• pp.263-270
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• 2005

An experimental study was performed to investigate the effects of partially premixing, varying the equivalence ratios from $0.79{\sim}{\infty}$, on NOx emissions and chemiluminescence of excited $OH^{\ast},\;CH^{ast}\;C_2^{\ast}$ radicals in laminar partially premixed flames. the signal from the electronically excited state of $OH^{\ast},\;CH^{ast}\;C_2^{\ast}$ was detected through a band pass filter with a photo multiplier tube, which are processed to the intensity ratio ($C_2^{\ast}/CH^{\ast},\;C_2^{\ast}/OH^{\ast},\;and\;CH^{\ast}/OH^{\ast}$) to reveal the correlation with local equivalence ratio. And measurements of NOx emission were made to investigate the relationship between visible flame appearance, chemiluminescence, and EINOX. The results demonstrated that (1) the flames at ${\phi}<1.59$ exhibited classical double flame structure, at ${\phi}>4.76$, the flames exhibited diffusion flame structure, and the intermediate flames at $1.59<{\phi}<4.76$ was a merged flame, (2) the $OH^{\ast}$ peak was located inside the $CH^{\ast}\;and\;C_2^{\ast}$ radical for all measured conditions and the emission intensity ratio of $C_2^{\ast}/CH^{\ast}\;and\;C_2^{\ast}/OH^{\ast}$ were identified as good marker for local equivalence ratio over a range of ${\phi}=0.79{\sim}1.2\;and\;CH^{\ast}/OH^{\ast}\;is\;0.79<{\phi}<1.9$. However, it was difficult to predict the equivalence ratio in partially premixed flames using this system for ${\phi}>2.38$, (3) the minimum NOX emission index (EINOx) is obtained for a equivalence ratio of 3.19 in the intermediate flames.

• Macromolecular Research
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• 제13권3호
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• pp.187-193
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• 2005

The TEMPO-mediated living free-radical bulk and dispersion polymerization of styrene in the presence of camphorsulfonic acid (CSA) are investigated. In the absence of TEMPO and CSA in the bulk polymerization, a conversion of $93\%$ is achieved within 6 hr of polymerization. When only TEMPO is involved in this polymerization, the pseudo-living free-radical polymerization is well achieved, however, the polymerization rate becomes quite slow. This retardation of the polymerization rate is solved by the addition of a low concentration of CSA. In the TEMPO-mediated dispersion polymerization in the presence of CSA, similar trends in the conversion, kinetics, and PDI are observed as those observed in the case of bulk polymerization. When only TEMPO is used in the dispersion polymerization, the resulting particle size becomes quite broad, due to the prolonged polymerization time. However, when a 1.0 molar ratio of CSA to TEMPO is added to the TEMPO-mediated dispersion polymerization, fairly mono-disperse PS microspheres having an average size of 5.83 $\mu$m and a CV of 3.4$\%$ are successfully obtained, due to the narrow molecular weight distribution of the intermediate oligomers and shortening of the polymerization time. This result indicates that the addition of CSA to the TEMPO-mediated bulk and the use of dispersion polymerization not only shortens the polymerization time, but also greatly improves the uniformity of the microspheres.

• Bulletin of the Korean Chemical Society
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• 제15권10호
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• pp.857-860
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• 1994

We have calculated the ${\pi}$-electron density, atom self-polarizability, and free valence on each atom of N-(2-chlorobenzyl)-pyridinium, N-(benzyl)-2-chloropyridinium, and N-(2-chlorobenzyl)-2-chloropyridinium salts using a simple Huckel method in order to discuss their intramolecular photocyclization reaction in a qualitative method. Our calculation qualitatively predicts that photocyclization occurs through forming radicals as a reaction intermediate by breaking a C-Cl bond after photoexcitation into a triplet state via intersystem crossing from an initially excited singlet state. We noticed that this C-Cl bond breaking is aided by ${\pi}$-complex formation between a chlorine atom and the ${\pi}$ -electrons of the neighboring ring in the triplet state and a stronger ${\pi}$-complex bond makes C-Cl bond breaking, i.e., radical formation, much easier. A chlorine atom will form a stronger ${\pi}$ -complex bond to a benzyl ring of N-(benzyl)-2-chloropyridinium than a pyridinium ring of N-(2-chlorobenzyl)-pyridinium because the former can donate its ${\pi}$-electron more easily than the latter. The chlorine at position 15 of N-(2-chlorobenzyl)-2-chloropyridinium salt in the excited state also provides its ${\pi}$-electron to the benzyl ring. So this ${\pi}$-electron can increase the bond strength of the $\pi-complex.$ Therefore, the strength of ${\pi}$-complex follows the order of N-(2-chlorobenzyl)-2-chloropyridinium, N-(benzyl)-2-chloropyridinium, and N-(2-chlorobenzyl)-pyridinium salts and thus the radical formation rate. This provides us with an intramolecular photocyclization reaction rate of the same order as given above.

• Bulletin of the Korean Chemical Society
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• 제12권2호
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• pp.163-169
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• 1991

The photochemical and photophysical properties of N-(2-haloarylmethyl)pyridinium, N-(arylmethyl)-2-halopyridinium, N-(2-haloarylmethyl)-2-halopyridinium salts and N-(2-halobenzyl)-isoquinolinium salt are studied. The pyridinium salts photocyclize to afford isoindolium salts, while the isoquinolium salts do not. In the photocyclization of N-(2-chlorobenzyl)-2-chloropyridinium salts, pyrido[2,1-a]-4-chloroisoindolium salt is formed by the cleavage of chlorine of pyridinium ring. This indicates that the excited moiety is not the phenyl ring, but the pyridinium ring. The triplet states of the pyridinium salts are believed to be largely involved in the photocyclization, since oxygen retards most of the reaction. Some assistance of a ${\pi}$-complex between the excited chlorine moiety of the salt and phenyl plane of the same molecule is required to explain the reactivity of the salts. N-(Benzyl)-2-chloropyridinium salt is two times more reactive than N-(2-chlorobenzyl)pyridinium salt. N-(Benzyl)-2-chloropyridinium salt can form ${\pi}-complex$ effectively because of the electron-rich phenyl group. The ${\pi}$-complex affords an intermediate, phenyl radical by cleaving the chlorine atom. The photocyclized product, isoindolium salt is obtained by losing the hydrogen atom from the phenyl radical. The reactive pyridinium salts 1a, 2a and 3a have a low fluorescence quantum yield (${\Phi}F$ < 0.01) and a higher triplet energy (ET > 68 kcal/mole) than the unreactive quinolinium salt. The unreactivity of isoquinolinium salt can be understood in relation to its high fluorescence quantum yield and its low triplet energy $(E_T = 61 kcal/mole).$.

• 한국자원식물학회지
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• 제29권4호
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• pp.479-494
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• 2016

기계수확에 적합하고 고기능성 유전자원을 선발하여 중부지역에 재배품종자원으로 공급하기 위하여 수수 100 자원을 공시하여 실시한 시험결과는 다음과 같다. 황금찰과 남풍찰을 대조 품종으로 하여 수집된 수수 100 자원의 작물학적 특성을 검정한 결과 출수소요일은 68~94일의 변이로 변이가 컸으며, 이삭형태는 7종류의 형태로 중간형이 가장 많이 나타났다. 간장은 70~429 ㎝의 변이로 변이 폭이 컸으며, 평균 260 ㎝였고, 100~150 ㎝가 31%로 최빈수였다. 이삭길이는 17~44.4 ㎝의 변이를 보였으며, 평균은 28.8 ㎝였다. 경태는 16.6~29.7 ㎜의 변이로 변이 폭이 컸으며, 평균은 21.4 ㎜였고, 엽수는 6.3~20개의 변이로 변이 폭이 컸으며, 평균은 11.4개였다. 천립중은 14.55~32.54 g의 변이로 변이 폭이 컸으며, 평균은 22.14 g이었고, 이삭당 수량은 18.32~44.96 g의 변이로 변이 폭이 컸으며, 평균은 30.74 g이었다. 작물학적 특성 검정을 통해 기계수확에 적합한 150 ㎝ 이하의 단간종이며, 이삭당 수량이 대조품종보다 높은 33.63 g 이상인 18 유전자원을 선발하였다. 선발된 18 유전자원 중 기능성물질 함량이 높은 자원 선발을 위하여 총 폴리페놀 함량, 전자공여능 및 총 안토시아닌 함량을 분석한 결과, 총 폴리페놀 함량은 대조품종인 황금찰은 174.08 ㎍ GAE/g이었으며, 남풍찰은 292.30 ㎍ GAE/g이었고, DS017, DS019, DS020, DS027, DS066이 대조품종인 남풍찰보다 함량이 높았다. 전자공여능은 대조품종인 황금찰이 26.25%였으며, 남풍찰은 33.65%였고, DS017, DS019, DS020, DS027, DS066, DS068, DS236이 대조품종인 남풍찰보다 소거능이 높거나 유사하였다. 총 안토시아닌 함량은 대조품종인 황금찰은 49.22 ㎍/g이었으며, 남풍찰은 51.52 ㎍/g이었고, DS488, DS428이 대조품종인 남풍찰과 황금찰보다 함량이 높거나 유사하였다. 그리고 항산화능과 항산화 성분과의 상관관계를 선형회귀분석 한 결과, 총 폴리페놀 함량과 DPPH radical 소거능 사이에 99.9% 수준으로 R=0.922의 높은 상관관계가 나타나 총 폴리페놀 함량이 높을수록 DPPH radical 소거능이 증가함을 알 수 있었다. 작물학적 특성 검정과 기능성물질 함량분석을 통하여 기계수확에 적합한 단간종이며, 이삭당 수량이 높고, 기능성물질 함량이 높은 DS017, DS019, DS020, DS027, DS066 5자원을 선발하였다.

• 대한화학회지
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• 제29권4호
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• pp.426-436
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• 1985

몇가지 벤즈아닐리드류를 합성하여 광반응시킨 후 생성물을 분리하고 그 구조를 결정하였다. 벤즈아닐리드 자체는 광고리화 안되고 Photo-Fries형 생성물을 주었지만 2-chlorobenzaniline, 2-bromobenzanilide, 및 2-methoxybenzanilide는 질소기류하에서 광고리화하여 모두 phenanthridone을 생성하였다. 2-chloro-2-nitrobenzanilide는 광고리화되지 않았다. 니트로기가 페닐고리에 도입되니 들뜬상태의 에너지가 낮아서 광고리화 안되었다. 2,2'-dichlorobenzanilide가 광고리화 되어 8-chlorophenanthridone이 되는 것으로 보아 들뜬 부분은 카르보닐쪽의 페닐 부분인것을 알 수 있었다. 2'-위치에 Cl이 있는 경우에도 광고리화 되었다. 2-chlorobenzanilide나 2'-chlorobenzanilide에 대하여 몇가지 용매중에서 광고리화 양자수득률을 구하였는데, 2-chlorobenzaniline는 효과적으로, 2'-chlorobenzanilide는 비효과적으로 광고리화 되었다. 대체로 비극성용매중에서 또 저점성용매중에서 양자수득률이 좋았다. 2-chlorobenzaniline가 광고리화 될때 산소의 영향을 시험하였는데, 산소가 존재하는 데서 광고리화가 잘 안되었다. 따라서 이때 삼중상태가 상관하는 것을 알았으며 전이상태는 염소원자가 떨어져 나가고 이때 이웃 페닐고리가 도우는 메카니즘을 제안한다. 삼중상태의 2-chlorobenzaniline에서 카르보닐쪽의 페닐과 N-페닐의 도움으로 카르보닐쪽의 페닐에 붙은 염소원자 떨어져나가 중간체인 컨쥬게이션된 라디칼이 된다. 이 라디칼에서 수소원자가 떨어져 나가 phenanthridone이 되는데, 이 단계는 속도결정단계가 아니다. 왜냐하면, 이 광고리화 반응에서 수소대신 중수소를 치환해도 속도에는 영향이 없기 때문이다. 2-methoxybenzanilide가 광고리화 될때는 산소가 존재하니 반응이 빨라졌다. 이는 단일 상태가 상관하는 것 같으며 산소가 중간체를 산화하여 반응을 촉진하는 것 같다.