Synthesis and Characterization of Organic Light-Emitting Copolymers Containing Naphthalene

Kim, Jung-Sik,Heo, Jun,Kang, Peng-Tao,Kim, Jin-Hak,Jung, Sung-Ouk,Kwon, Soon-Ki,Kim, Un-Kyung,Kim, Yun-Hi The Polymer Society of Korea 2009 Macromolecular Research Vol.17 No.2

Conjugated PPV-derived block copolymers containing 2-ethylhexyloxynaphthalene unit were synthesized and characterized in this study. The resulting polymers were soluble in common organic solvents and showed good thermal stabilities, The weight-average molecular weights ($M_w$) of the copolymers ranged from 246,000 to 475,000 with PDIs of $1.3{\sim}2.1$. The optical properties of these polymers, measured both in a chloroform solution and on a film, showed a maximum absorption at $405{\sim}476\;nm$ for Copolymers $I{\sim}VIII$. In the PL spectra, Copolymers $I{\sim}VIII$ showed maximum peaks at $510{\sim}566\;nm$. The HOMOs, LUMOs and band gaps of the PPV derivatives of Copolymers $I{\sim}VIII$ were $5.30{\sim}5.77$, $3.04{\sim}3.24$, and $2.5{\sim}2.2\;eV$, respectively, The multi-layered, light-emitting diodes of ITO/PEDOT/copolymers/LiF/Al exhibited turn-on voltages of $6{\sim}2.5\;V$ Copolymer VIII exhibited the maximum brightness of $3.657\;cd/m^2$. Particularly, Copolymer VII, with an identical composition of MEH-PPV and naphthalene-PPV, showed a maximum luminance efficiency and power efficiency of 2,63 cd/A and 1.06 lm/W, respectively.

Mapping of the Reduced Culm Number Trait in Rice (Oryza sativa L.) rcn10(t) Mutant

Un-Sang Yeo,Jong-Hee Lee,Choon-Song Kim,Meong-Gi Jeon,Tae-Yong Oh,Chang-Deok Han,Mun-Sik Shin,Byeong-Geun Oh 한국육종학회 2008 한국육종학회지 Vol.40 No.3

In rice, tillering is an important trait determining yield. To study tillering at the agricultural and molecular aspects, we have examined a spontaneous rice mutant that showed reduction in the number of culms. The mutant was derived from a F6 line of the cross of Junambyeo*4 / IR72. It could produce, on average, 4 tillers per hill in the paddy field while wild-type plants usually have 15. Except the reduced culm numbers, they also show pale green phenotypes. The phenotypes of this mutant were co-segregated as the monogenic Mendelian ratio (χ2 = 0.002, p = 0.969). In order to locate a gene responsible for the rcn phenotype, the mutant with the japonica genetic background was crossed with Milyang21 of the indica background. Bulked segregant analysis was used for rapid determination of chromosomal location. Three SSR markers (RM551, RM8213, and RM16467) on chromosome 4 were genetically associated with the mutant phenotype. Each of the 217 F2 plants was genotyped with simple sequence length polymorphisms. The data showed that RM16572 on chromosome 4 was the closest marker that showed perfect co-segregation among the F2 population. We suggest the new rcn gene studied here name as rcn10t because there was no report which exhibit a rcn phenotype with a pleiotropic effect of pale green (chlorophyll deficiency), and mapped at same position on chromosome 4.

Improvement in extrudability and mechanical properties of AZ91 alloy through extrusion with artificial cooling

Kim, Sang-Hoon,Lee, Jong Un,Kim, Ye Jin,Moon, Byoung Gi,You, Bong Sun,Kim, Ha Sik,Park, Sung Hyuk Elsevier 2017 Materials science & engineering. properties, micro Vol.703 No.-

<P><B>Abstract</B></P> <P>This study demonstrates that the application of artificial water cooling during extrusion effectively increases the extrudability of the AZ91 alloy and significantly improves the mechanical properties of the extruded AZ91 alloy. The artificial cooling dramatically reduces the actual temperature of the deformation zone, which results in an increase in the maximum exit speed at which the alloy is extrudable without the occurrence of hot cracking from 4.5m/min to 7.5m/min. It also promotes dynamic recrystallization and precipitation behaviors during extrusion, which leads to a reduction in grain size and an increase in the amount of fine Mg<SUB>17</SUB>Al<SUB>12</SUB> precipitates. As a result, for the AZ91 alloy extruded at an exit speed of 1.5m/min, the tensile and compressive yield strengths improve significantly by 51MPa and 114MPa, respectively, and its tension–compression yield asymmetry reduces from 0.73 to 1.02 owing to the refinement of the grain size by artificial cooling. In addition, the AZ91 alloy extruded at an exit speed of 7.5m/min with artificial cooling exhibits a finer grain structure than and superior mechanical properties to the AZ91 alloy extruded at a slower exit speed of 4.5m/min without artificial cooling. This result indicates that the application of artificial cooling can simultaneously improve the maximum extrusion speed and the tensile and compressive properties of Mg alloys.</P>

Highly efficient and highly stable terpolymer-based all-polymer solar cells with broad complementary absorption and robust morphology

Kim, Aesun,Park, Chang Geun,Park, Su Hong,Kim, Hyung Jong,Choi, Suna,Kim, Young Un,Jeong, Choel Hun,Chae, Weon-Sik,Cho, Min Ju,Choi, Dong Hoon The Royal Society of Chemistry 2018 Journal of materials chemistry. A, Materials for e Vol.6 No.21

<P>A novel conjugated terpolymer referred to as Ter-3MTTPD was successfully synthesized using 4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-<I>b</I>:4,5-<I>b</I>′]dithiophene as a donor and methyl thiophene-3-carboxylate (3MT) and 5-(2-ethylhexyl)-4<I>H</I>-thieno[3,4-<I>c</I>]pyrrole-4,6(5<I>H</I>)-dione (TPD) as acceptor units to investigate the effects of the terpolymer structure on the optical and electrochemical properties. The performance of an all-polymer solar cell (all-PSC) was comprehensively examined by blending the terpolymer with 2,7-bis(2-hexyldecyl)-4-(selenophen-2-yl)benzo[lmn][3,8]phenanthroline-1,3,6,8(2<I>H</I>,7<I>H</I>)-tetraone (NDI-Se). The as-cast blend film of Ter-3MTTPD:NDI-Se exhibits the highest power conversion efficiency of 7.66% in the all-PSC. This was further supported by the results of time-resolved photoluminescence (TRPL) in Ter-3MTTPD:NDI-Se blend film states which yielded the highest PL quenching efficiency (90%) resulting from the shortest average lifetime, <I>τ</I>ave of ∼67 ps, much smaller than those of the two binary copolymer blend films (<I>e.g.</I>, <I>τ</I>ave = 194 ps and 149 ps, respectively, for Co-3MT:NDI-Se and Co-TPD:NDI-Se). In addition, for an as-cast blend film of Ter-3MTTPD:NDI-Se in the active layer, the shelf-life (∼1000 h) of the all-PSC under ambient conditions was found to be much better compared to those of PSCs based on the other two binary copolymers, Co-3MT and Co-TPD.</P>

Pectinase-treated <i>Panax ginseng</i> protects heat stress-induced testicular damage in rats

Kim, Min Kyoung,Cha, Kyu-Min,Hwang, Seock-Yeon,Park, Un-Kyu,Seo, Seok Kyo,Lee, Sang-Ho,Jeong, Min-Sik,Cho, SiHyun,Kopalli, Spandana Rajendra,Kim, Si-Kwan BioScientifica Ltd 2017 Reproduction Vol.153 No.6

<P>Testicular hyperthermia is well studied to cause impaired spermatogenesis. In the present study, the protective effect of enzymatically modified (pectinase-treated) Panax ginseng (GINST) against intermittent sub-chronic heat stress-induced testicular damage in rats was investigated. Male Sprague-Dawley rats were divided into four groups: normal control (NC), heat-stressed control (HC), heat- stressed plus GINST-100mg/kg/day (HG100) and heat- stressed plus GINST-200mg/kg/day (HG200) treatment groups. GINST (100 and 200mg/kg/day) was mixed separately with a regular pellet diet and was administered orally for 8 weeks starting from 1 week before heat exposure. Parameters such as organ weight, blood chemistry, sperm kinetic values, expression of antioxidant enzymes, spermatogenesis molecules and sex hormone receptors levels were measured. Data revealed that kidney and epididymis weight were significantly (P < 0.05) decreased with heat stress and recovered by GINST treatment. Further, the altered levels of blood chemistry panels and sperm kinetic values in heat stress-induced rats were attenuated when GINST was administered (P < 0.05). Furthermore, the expression levels of antioxidant-related enzymes (GSTM5 and GPX4), spermatogenesis-related proteins (CREB1 and INHA) and sex hormone receptors (androgen receptor, luteinizing hormone receptor and follicle-stimulating hormone receptor) were reduced by heat stress; however, GINST treatment effectively ameliorated these changes. In conclusion, GINST was effective in reducing heat-induced damage in various male fertility factors in vivo and has considerable potential to be developed as a useful supplement in improving male fertility.</P>

Two Crystal structures of Fully Dehydrated Partially Magnesium Exchanged Zeolite A, $Mg_{1.5}Na_9-A\;and\;Mg{2.5}Na_7$-A

Kim, Yang,Lee, Suk-Hee,Park, Jong-Yul,Kim, Un-Sik Korean Chemical Society 1989 Bulletin of the Korean Chemical Society Vol.10 No.4

Two Crystal structures of fully dehydrated partially magnesium exchanged zeolite A, stoichiometries of $Mg_{2.5}Na_7-A$ (a = 12.251 (1) ${\AA}$) and $Mg_{1.5}Na_9-A\; (a\;=\;12.214(1)\;{\AA})$ per unit cell, have been determined from the 3-dimensional X-ray diffraction data gathered by counter methods. All structures were solved and refined in the cubic space group Pm3m at 21(1)$^{\circ}C$. The structures of the dehydrated $Mg_{2.5}Na_7-A$ and $Mg_{1.5}Na_9-A$ were refined to yield the final error indices $R_1$ = 0.042 and $R_2$ = 0.049 with 318 reflections, and $R_1$ = 0.034 and $R_2$ = 0.032 with 252 reflections, respectively, for which I > $3{\sigma}(I)$. Both structures indicate that $Mg^{2+}$ ions are coordinated by three framework oxygens and the angle substended at $Mg^{2+}$ ions, O(3)-Mg(1)-O(3) is ca. $120^{\circ}$, close to the idealized trigonal planar value. $Mg^{2+}$ ions preferentially occupy 6-ring sites and $Na^+$ ions occupy 8-ring sites when total number of cations per unit cell is more than 8.

Nitrogen Dynamics in Soil Amended with Different Rate of Nitrogen Fertilizer

Kim, Sung Un,Choi, Eun-Jung,Jeong, Hyun-Cheol,Lee, Jong-Sik,Lee, Hyun Ho,Park, Hye Jin,Hong, Chang Oh Korean Society of Soil Science and Fertilizer 2017 한국토양비료학회지 Vol.50 No.6

Excessive application of nitrogen (N) fertilizer to support switchgrass growth for bioenergy production may cause adverse environmental effects. The objective of this study was to determine optimum N application rate to increase biomass yield of switchgrass and to reduce adverse environmental effects related to N. Switchgrass was planted in May 2008 and biomass yield, N uses of switchgrass, nitrate ($NO_3$) leaching, and nitrous oxide ($N_2O$) emission were evaluated from 2010 through 2011. Total N removal significantly increased with N rate despite the fact that yield did not increased with above $56kg\;N\;ha^{-1}$ of N rate. Apparent nitrogen recoveries were 4.81 and 5.48% at 56 and $112kg\;N\;ha^{-1}$ of N rate, respectively. Nitrogen use efficiency decreased into half with increasing N rate from 56 to $112kg\;N\;ha^{-1}$. Nitrate leaching and $N_2O$ emission were related to N use of switchgrass. There was no significant difference of cumulative $NO_3$ leaching between 0 and $56kg\;N\;ha^{-1}$ but, it significantly increased at $112kg\;N\;ha^{-1}$. There was no significant difference of cumulative $N_2O$ emission among N rates in crest, but it significantly increased at $112kg\;N\;ha^{-1}$ in toe. Excessive N application rate (above $56kg\;N\;ha^{-1}$) beyond plant requirement could accelerate $NO_3$ leaching and $N_2O$ emission in switchgrass field. Overall, $56kg\;N\;ha^{-1}$ might be optimum N application rate in reducing economic waste on N fertilizer and adverse environmental impacts.

Two Crystal Structures of Fully Dehydrated Partially Magnesium Exchanged Zeolite A, Mg_(1.5)Na_(9)-A and Mg_(2.5)Na_(7)-A

Kim, Yang,Lee, Suk Hee,Park, Jong Yul,Kim, Un Sik 부산대학교 기초과학연구소 1989 부산대학교 기초과학연구소 연구논문집 Vol.9 No.-

Two Crystal structures of fully dehydrated partially magnesium exchanged zeolite A, stoichiometries of Mg2.5Na7-A, (a=12.251(1)Å) and Mg1.5Na9-A(a=12.214(1)Å) per unit cell, have been determined from the 3-dimensional X-ray diffraction data gathered by counter methods. All structures were solved and refined in the cubic space group Pm3m at 2I(1)˚C. The structures of the dehydrated Mg2.5Na7-A and Mg1.5Na9-A were refined to yield the final error indices R1=0.042 and R2=0.049 with 318 reflections, and R1=0.034 and R2=0.032 with 252 reflections,respectively,for which I>3σ(I).Both structures indicate that Mg2+ ions are coordinated by three framework oxygens and the angle substended at Mg2+ ions,O(3)-Mg(1)-O(3) is ca. 120˚,close to the idealized trigonal planar value.Mg2+ ions preferentially occupy 6-ring sites and Na+ ions occupy 8-ring sites when total number of cations per unit cell is more than 8.

Crystal Structures of Vacuum Dehydrated Fully Cd²+ -Exchanged Zeolite A and Its Ethylene Sorption Complex

Kim, Un Sik,Kim, Duk Soo,Koh, Kwang Nak,Kim, Yang 濟州大學校 基礎科學硏究所 1991 基礎科學硏究 Vol.4 No.1

The crystal structure of dehydrated fully ?? - exchanged zeolite A evacuated at ?? Torr and 450℃ (a=12.225(2) Å) and of its ethylene sorption complex (a=12.219(2) Å) have been determined by single crystal X-ray diffraction techniques in the cubic space group Pm3m at 21(1)℃. The structures were refined to final error indices, R₁=0.063 and R₂=0.065 with 266 reflections and R₁=0.055 and R₂=0.062 with 260 reflections, respectively, for which I>3σ(I). In both structures, six ?? ions lie at two distinguished three-fold axes of unit cell. Dehydrated ?? sorbs 4 ethylene molecules per unit cell at 25℃(vapor pressure of ethylene is ca. 100 Torr). Each ?? ion forms a lateral π complex with an ethylene molecule. Four ?? ions exist in a nearly tetrahedral environment, 2.210(7) Å apart from three framework oxygen ions (considering ethylene molecule as a monodentate ligand) and 2.67(6) Å from each carbon atom of ethylene molecule.

Nuclear Magnetic Relaxation Study on the Interaction of Water with Hydrophilic Polymers

Kim,Sik Un,Sung,Yong Kiel,Kang,Shin Won 동국대학교 자연과학연구소 1981 자연과학연구 논문집 Vol.1 No.-

친수성 메타크리레이트 고분자와 물 사이의 상호작용을 펄스 NMR분광법에 의해서 연구하였다. 그 3차원적 친수성 메타크리에이트 고분자는 HEMA단량체와 EGDMA및 TEGDMA와 같은 가교제를 사용해서 제조하였다. 그 NMR연구에 의함년 적은 양의 물을 함융하고 있는 겔에 대한 스핀-라티스 이완시간(T₁)은 두 종류의 T₁와 T₁가 측정되어, 두 가지 종류의 결합수, 즉 강하게 결합된 물과 약하게 결합된 물이 존재하고 있음을 나타내 주었다. Poly(HEMA)수화겔 속에 있는 결합수의 스핀-라티스 이완시간은 얼음 속에 있는 물 자체의 프로톤의 스핀-라티스 이완시간(-16.40℃에서T₁=0.829sec)보다 훨씬 짧았다. 이 사실은 겔과 결합된 물 아시의 상호작용이 얼음 속에 있는 물 분자들 사이의 상호작용 보다도 강하다는 것을 보여준다. 수화겔 속의 물 프로톤에 대해서 측정한 T₁값은 순수한 액체 물(34℃에서 T₁=4.50sec)에 대한 값보다 훨씬 줄어들었다. 그리고 겔 속에 물의 양이 증가됨에 따라 펄스증폭강도는 단일지수함수의 성질을 보여주었다. 그 수화겔 속에 있는 물 프로튼에 대한 스핀-스핀 이완시간(T₂)의 측정값은 T₁측정값보다 약10배 낮았으며 적은 양의 물을 함유하고 있는 영역에서는 거이 일정하게 유지되었다. 결합수만을 함유하는 영역을 벗어나서 T₂의 측정값은 물의 함유량이 증가함에 따라 급격히 증가함을 나타내 주었다. 이 사실은 많은 양의 물을 함유하는 수화겔에서는 계면의 물이나 벌크상태의 물의 양이 더 많이 존재하게 되어 물 프로톤의 이동노가 증가하고 있다는 증거가 된다. The interaction of water with hydrophilic methacrylate polymers have been studied by using pulse NMR relaxation spectroscopy. The hydrophilic three dimensional methacrylate polymers were prepared from 2-hydroxyethyl methacrylate(HEMA) monomer and crosslinkers such as ethylene glycol dimethacrylate (EGDMA) and tetraethylene glycol dimethacylate (TEGDMA). The NMR relaxation studies showed that the spin-lattice relaxation times (T₁) of low water sontent gels show a double environments resulting in two spin-lattice relaxation times (T₁andT₁). The data indicate that there are two different kinds of bound water, i.e., strongly bound water and weakly bound water. The spin-lattice relaxation time of bound water in poly(2-hydroxyethyl methacrylate) dydrogels is much less than that of water protons in ice (T₁=0.829 set at -16.40). This fact shows that the interactions between the bound water molecules and the gel networks are stronger than that between the water molecules in ice. The measuted values for the water protons in the hyrdogels are gresatly reduced compared to that of liquid water (T₁=4.50 sec at 34). As the water content in the gels is increased, the pulse amplitude intensities show a single exponential begavior. The measuted values of spin-spin relaxation times (T₂) of the water protons in the hydorgels are approximately ten times less than that of T₁and are almost constant in the region of bound water content. Beyond the bound water contenct region, the T₂values rapidly increse as the water content increases. This evidence indicates that more interfacial and bulk-like water exists, resulting in a mobility increse in high water content hydrogels.