• Title/Summary/Keyword: Leaving group effect

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A Kinetic Study on Aminolysis of 2-Pyridyl X-Substituted Benzoates: Effect of Changing Leaving Group from 4-Nitrophenolate to 2-Pyridinolate on Reactivity and Mechanism

  • Lee, Jong-Pal;Bae, Ae-Ri;Im, Li-Ra;Um, Ik-Hwan
    • Bulletin of the Korean Chemical Society
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    • v.31 no.12
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    • pp.3588-3592
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    • 2010
  • Second-order rate constants ($k_N$) have been measured spectrophotometrically for nucleophilic substitution reactions of 2-pyridyl X-substituted benzoates 8a-e with a series of alicyclic secondary amines in $H_2O$ at $25.0{\pm}0.1^{\circ}C$. The $k_N$ values for the reactions of 8a-e are slightly smaller than the corresponding reactions of 4-nitrophenyl X-substituted benzoates 1a-e (e.g., $kN^{1a-e}/k_N^{8a-e}$ = 1.1 ~ 3.1), although 2-pyridinolate in 8a-e is ca. 4.5 $pK_a$ units more basic than 4-nitrophenolate in 1a-e. The Br$\o$nsted-type plot for the aminolysis of 8c (X = H) is linear with $\beta_{nuc}$ = 0.77 and $R^2$ = 0.991 (Figure 1), which is typical for reactions reported previously to proceed through a stepwise mechanism with breakdown of a zwitterionic tetrahedral intermediate $T^{\pm}$ being the rate-determining step (RDS), e.g., aminolysis of 4-nitrophenyl benzoate 1c. The Hammett plot for the reactions of 8a-e with piperidine consists of two intersecting straight lines (Figure 2), i.e., $\rho$ = 1.71 for substrates possessing an electron-donating group (EDG) while $\rho$ = 0.86 for those bearing an electron-withdrawing group (EWG). Traditionally, such a nonlinear Hammett plot has been interpreted as a change in RDS upon changing substituent X in the benzoyl moiety. However, it has been proposed that the nonlinear Hammett is not due to a change in RDS since the corresponding Yukawa-Tsuno plot exhibits excellent linear correlation with $\rho$ = 0.85 and r = 0.62 ($R^2$ = 0.995, Figure 3). Stabilization of substrates 8a-e in the ground state has been concluded to be responsible for the nonlinear Hammett plot.

Solvation in Mixed Solvent (III). Solvatochromic Analysis for the Solvent Effect of Binary Mixed Solvent (혼합용매에서의 용매화 (제3보). 이성분 혼합용매 중에서 용매효과에 대한 분광용매화 분석)

  • Lee, Ik-Choon;La, Sang-Mu;Lee, Bon-Su;Sohn, Se-Chul
    • Journal of the Korean Chemical Society
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    • v.28 no.4
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    • pp.210-216
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    • 1984
  • Solvatochromic comparison methods were applied to determine Taft's solvent parameters, ${\pi}^{\ast}$(solvent polarity-polarizability), ${\alpha}$(solvent hydrogen bond donor acidity) and ${\beta}$ (solvent hydrogen bond acceptor basicity) for MeOH-MeCN solvent mixtures. Swain's solvent parameters A(anion solvation scale) and B(cation solvation scale) were also determined by least square fitting of kinetic data in the same binary solvent mixtures. It was found that: (i)${\beta}$ depends on the basicity of the solvent and increases with the MeOH content owing to the increase in polymeric structure of methanol; (ii) ${\pi}^{\ast}$depends on the dipole moment of the solvent and increases with the MeCN content of the solvent; (iii) ${\alpha}$ increases rapidly with the MeOH content as the hydrogen bond donor acidity of the solvent mixtures increases. Taft's reaction constants a and s and Swain's reaction constants a and b were determined for the reactions reported from our laboratory previously using solvent parameters determined in this work. No meaningful inter-relationship was found between the two set of reaction parameters, but a good linear correlation was found between the ratios a/s and a/b. Solvent effect on the reaction mechanism, substituent effect and leaving group ability were examined in the light of these reaction constants ratios.

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Design and Implementation of Safe-Guard for Elementary School Students (초등학생 안전도우미 설계 및 구현)

  • Kim, Jin-Mook;Moon, Jeong-Kyung
    • Journal of the Korea Convergence Society
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    • v.4 no.2
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    • pp.29-33
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    • 2013
  • From one elementary school of last 2005 Pusan was started "the school police" system is being applied the effect in the elementary school of the human nature receiving entire country. But "with school police system " have a limit about manpower that is insufficient. So we try to make "Baumter-Gikimy " that is extended scollo police in seoul. Despite being like that at 2010 and 2011 cannot forget the elementary student suicide events which are shocking or sexual assault events occur from the campus.From elementary school 4 grade the students between junior high school 1 grade crime occurrence ratio are highest. These people the group leaving out mainly, suicide, with group violence and sexual assault problem gets up same problems. In order to solve like this problems stands the countermeasure of the dimension which is national certainly is necessary. But so far only the damage student and the parents have an interest in about like this problems and they hurt. We the smart phone of Android bases it will be able to solve like this problem points [ayp] from under planning and development boil the elementary student safe helper it will can use. When it uses the elementary student safe helper system which we propose before the accident occurs, it will grasp the state information of the student and it will be able to prevent an accident in advance. We will try to more efficient safe guard to elementary school student by real-time monitoring skill soon.

Periodontal regenerative effect of a bovine hydroxyapatite/collagen block in one-wall intrabony defects in dogs: a histometric analysis

  • Jung, Ui-Won;Lee, Jung-Seok;Park, Weon-Yeong;Cha, Jae-Kook;Hwang, Ji-Wan;Park, Jung-Chul;Kim, Chang-Sung;Cho, Kyoo-Sung;Chai, Jung-Kiu;Choi, Seong-Ho
    • Journal of Periodontal and Implant Science
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    • v.41 no.6
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    • pp.285-292
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    • 2011
  • Purpose: The aim of this study was to elucidate the effect of a bovine hydroxyapatite/collagen (BHC) block in one-wall intrabony periodontal defects in dogs. Methods: A one-wall intrabony periodontal defect (4 mm wide and 5 mm deep) was prepared bilaterally at the mesial side of the mandibular fourth premolar in five beagle dogs. After thorough root planing, block-type BHC ($4{\times}5{\times}5$ mm) was placed on one side. The contralateral defect area did not receive any material as a sham-surgery control. Histological analysis of the sites was performed after an 8-week healing period. Results: Two of five samples in the experimental group healed well without dissipation of the graft materials, and histological analysis revealed excellent regeneration of the periodontal tissues. However, most of the grafted materials had been displaced in the other three samples, leaving only a small portion of the graft. The measured parameters exhibited large standard deviations, and the mean values did not differ significantly between the experimental and sham-surgery control sides. Conclusions: The application of BHC alone-without a barrier membrane-to wide, one-wall intrabony periodontal defects yielded inconsistent results regarding both periodontal regeneration and substantivity of the graft materials. Thus, the use of a barrier membrane for noncontained-type defects is recommended to improve the stability of the grafted material, and to condense it.

A Dynamic Study of Women's Labor Market Transitions: Career Interruptions and its Determinants (여성의 동태적 노동공급 - 취업연속성과 첫 노동시장 퇴출행태를 중심으로 -)

  • 김영옥
    • Korea journal of population studies
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    • v.25 no.2
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    • pp.5-40
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    • 2002
  • Using detailed data of women's work history, this study analyses the transition process between employment and non-employment over the life history in order to identity individual and structural determinants in the processes. Korean women comprise very heterogeneous groups in terms of work continuity: one group having a continuous work history and another having an interrupted work experience. While 4.0% of total women have stayed in the labor market since leaving school, 17.3% have not worked outside at all and remaining 87.9% have experienced into and out of the labor market at least once. On the average, the cumulated time of employment per woman is 8.2 years and the cumulated time of unemployment is 13.1 years. Thus Korean women work a total of only 38.5% of their whole lifetime after leaving school. We can conclude that the increase of the employment rate of married women in Korea since the 1970s has been due to the increase of the new entrants with short or little working careers into the labor market, not to the increase of women's work continuity on the whole. A women's educational achievement does not seem to be positively related to employment duration, contrary to the suggestion of the human capital theory, Rather, family variables, especially the existence of the child under 6 yens old, is a more significant determining factor for an individual's exit from employment. And there is little difference among different age cohorts which implies little improvement in the employment continuity of younger women. This study also documents the importance of structural variables, such as the type of occupation, as significant determining factors for the hazard rate. Specially women with professional jobs tend to stay longer in the labor market. Therefore, women's entry into more professional occupations is expected to contribute to the continuity of employment. Our results also show that duration-dependence is not spurious. When unobserved heterogeneity is controlled, the negative relation between the rate from employment and the duration of employment does not disappear.

Photochemistry of Benzanilide I Photocyclization of Benzanilides (벤즈아닐리드류의 광화학 (제1보). 벤즈아닐리드류의 광고리화 반응)

  • Yong-Tae Park;Sang-Rok Do;Kap-Duk Lee
    • Journal of the Korean Chemical Society
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    • v.29 no.4
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    • pp.426-436
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    • 1985
  • Preparative and kinetic photochemical reactions of several benzanilides were studied. Several substituted benzanilides were synthesized by acylation of substituted anilines with substituted benzoyl chlorides. While benzanilide gave a photo-Fries type reaction product, 2-chlorobenzaniline, 2-bromobenzanilide, and 2-methoxybenzanilide gave a photocyclization reaction product, phenanthridone. Since 8-chlorophenanthridone was obtained from 2,2'-dichlorobenzanilide, the carbonyl phenyl is the excited site. Quantum yield of photocyclization of 2-chlorobenzanilide, 2'-chlorobenzanilide, and 2-methoxybenzanilide were obtained. 2-Chlorobenzanilide was photocyclized effectively and 2'-chlorobenzanilide ineffectively. Since the oxygen present in the reaction medium retarded the photocyclization reaction of 2-chlorobenzanilide, the triplet state of 2-chlorobenzanilide is involved. The mechanism of the photocyclization of 2-chlorobenzanilide is suggested: $\pi-complex$ between carbonyl phenyl and N-phenyl was formed from the triplet state of 2-chlorobenzanilide; neighbour phenyl (N-phenyl) assists for leaving of chlorine from carbonyl phenyl to make an intermediate, cyclized conjugated radical, because electron donating group on the N-phenyl ring accelerated the reaction; hydrogen detachment from the intermediate is obviously not a rate determined step because there was no isotope effect on the rate of photocyclization. The photocyclization reaction rate of 2-methoxybenzanilide was faster in the presence of oxygen than in the absence of oxygen. Thus, the singlet excited state of 2-methoxybenzanilide is involved in the reaction. Probably, the intermediate, methoxyhydro-phenanthridone is oxidized by oxygen in the medium to give phenanthridone.

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A study of the Life-Course perspective - The exploratory analysis of Transitions to adulthood - (생애과정 관점에 대한 고찰과 적용 - 성인으로의 이행과정에 대한 탐색적 분석 -)

  • Moon, Hey jin
    • Korean Journal of Social Welfare Studies
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    • v.41 no.3
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    • pp.349-378
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    • 2010
  • The Life-Course perspective is a theoretical orientation that views the life-course as the age structure embedded in social institutions and history and understands the life-course of individual and group in the contextual perspective. The life-course perspective studies were developed in Germany and North America. They study social and historical effects and the effect of institutions and the state on the life-course, the pathway of the work career and differences of labour outcomes, and the inequality that is developed in the life-course. In Korea, the life-course perspective studies were tried in various fields and cumulated. However, it didn't established as a theoretical orientation. For applying the life-course perspective to connect the individual life-course with social and historical event, I describe the historical location of individuals born between 1930 and 1979 and analyse the change of their transitions to adulthood exploratorily. On results, the extension of education made the structural change of their life-course, and in young cohort the timing of leaving school, entering workforce, marriage and childbirth was delayed and transitions were made in narrower spread. It means the standardization of the life-course as appears in modern society. The 1970s birth cohort has the differenciated life-course pattern, however I cannot verify that change because of the right censoring.

Effect of Nandrolone Decanoate on Disuse Muscle Atrophy and Bone Beating in Dogs (개에서 불용성 근위축과 골절 치유에 대한 Nandrolone decanoate의 효과)

  • Yun Seong-jin;Lim Ji-hey;Rahman Md. Mizanur;Byeon Ye-eun;Kim Wan-hee;Kweon Oh-kyeong
    • Journal of Veterinary Clinics
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    • v.22 no.4
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    • pp.336-341
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    • 2005
  • Anabolic steroid compounds are widely used for the increase of muscle mass, density of bone and athletic ability. The present study conducted to evaluate the effects of nandrolone decanoate (ND), one of the anabolic steroid compounds, on disuse muscle atrophy and healing process of bone in dogs. Twenty physically healthy dogs of both sexes were used in this experiment and divided into three groups: group A (control), group B (low dose M-1.5 mg/kg) and group C (high dose ND-7.5 mg/kg). One-mm strip of full thickness bone was excised from the radius below the pronator teres muscle for the artificial fracture and then the fractured ends were fixed in apposition with bone plate leaving 1mm gap, and finally immobilized externally by Robert John's bandage for 4 weeks. ND was administered intramuscularly once a week far 8 weeks. Body weight, muscle mass change and fracture gap of the bone were evaluated immediately after surgery, and 2, 4, and 8 weeks after surgery. The rates of muscle mass change 8 weeks after surgery were $-2.75\pm0.16\%,\;1.68\pm0.11\%\;and\;1.74\pm0.48\%$ in groups A, B and C, respectively. The significant increase (p<0.05) of muscle mass increments were found in the treated groups. The fibrous connective tissue layer in the fracture gaps of the treated groups increased more than the control, especially in the group C at 4th week. More dense fibrous connective tissue were found in the treated groups at 8th week. Collectively, our results suggested that ND was an effective anabolic agent for the immobilized disuse muscle and bone healing.

The effect of antagonists produced by Paenibacillus polymyxa CK-1 on the growth of Trichoderma sp. (Paenibacillus polymyxa CK-1이 생산한 길항물질이 Trichoderma sp. 생육에 미치는 영향)

  • Lee, Sang-Won;Choi, Jin-Sang;Kim, Chul-Ho
    • Journal of Mushroom
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    • v.12 no.3
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    • pp.201-208
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    • 2014
  • The separation of the bacteria inhibiting Trichoderma sp. mold, the strain causing blue mold disease that occurs frequently when cultivating mushroom while carrying out the efficient fermentation of mushroom medium, from the growth was done. In about 200 strains isolated primarily from fungus garden samples, 6 strains were secondly isolated, which had fast growth rates and a clear zone on the plate medium of SM, AM, and CM. Among the 6 strains isolated, the C-1 strain showed high enzymatic activity of cellulase, amylase, and protease, and strong antibacterial activity for the T. virens and T. harzianum, selected finally. The selected C-1 strain was identified as Paenibacillus polymyxaby the result of the identification by Bergey's Manual of Systematic Bacteriology and the analysis of the nucleotide sequence of 16S rRNA, and named as P. polymyxa CK-1. In reviewing the growth conditions of the P. polymyxa CK-1 strain, the optimum cultivation temperature was $45^{\circ}C$, and the optimum pH for growth was in the range of 6.0~7.0. Appropriate incubation time of P. polymyxa CK-1 for the growth inhibition of the fungus T. virens and T. harzianum was 22 to 36 hours. And the fungal growth was not observed, even when leaving two molds inoculated on each petri dishes, which were treated with 24 hour culture solution of P. polymyxa CK-1 strain for 10 days. As a result of studying the thermal stability of the antagonists produced by the P. polymyxa CK-1 strain, no mycelial growth of the two fungi was observed in the test group treated for 20 minutes at $60^{\circ}C$ and $100^{\circ}C$, but mycelial growth was slightly observed in the test group treated for 20 minutes at $121^{\circ}C$. As aresult of reviewing the impact of the P. polymyxa CK-1 culture medium on mushroom mycelial growth, it showed no effect on a variety of mushroom mycelial growth including enoki mushroom and shiitake mushroom.

A Study on type and characteristics of organization-related negative affect. (조직관련상황에서 구성원이 느끼는 불안 정서의 유형과 특성에 관한 연구)

  • Jong Dae Kim
    • Korean Journal of Culture and Social Issue
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    • v.21 no.4
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    • pp.617-647
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    • 2015
  • The purposes of this study was to develop a valid scale measuring organization-related anxiety and to use this scale to examine the relation of organizational anxiety to demographic variables, job satisfaction and organizational committment. A series of studies were conducted to develop a scale for organizational anxiety. Initially, the 97 items were adopted by expert ratings. A exploratory factor analysis with a sample of 435 workers yielded a preliminary version of organizational anxiety scale with 28 items. Subsequently, a confirmatory factor analysis was conducted with a sample of 566 workers, leaving 20 items. The final version of the organizational anxiety scale consisted of 4 sub-factors: perception of future uncertainty, perception of locus of control, interpersonal anxiety, and perception of alternatives. In this study, the examined demographic characteristics included sex, age, type of occupation, type of industry, occupational position, monthly income and educational level. Organizational effectiveness was composed of job satisfaction and organizational commitment. As mediators, organizational culture, life satisfaction, self efficacy, and social support were explored. The negative relationship was observed between organizational anxiety and organizational effectiveness. The results showed the significant differences in organizational anxiety by demographic characteristics. The mediators were explored for the relationship between organizational anxiety and job satisfaction and between organizational anxiety and organizational commitment. The negative relationship between organizational anxiety and job satisfaction was mediated by the group culture, the developmental culture, the rational culture, life satisfaction, self-efficacy, and social support. Individuals with the higher level of these mediators reported greater job satisfaction even if they experienced organizational anxiety. The partial mediation effect of the group culture, the developmental culture, the rational culture, life satisfaction, and social support was observed on the negative relationship between organizational anxiety and organizational commitment. These results implies that job satisfaction and organizational commitment can be improved with the interventions on organizational cultures, self-efficacy, and social support despite the presence of organizational anxiety. Based on these results, the implication and limitations of this study and the directions for future research discussed.