Efficient Surface Neutralization and Enhanced Substrate Adhesion through Ketene Mediated Crosslinking and Functionalization

Jung, Hyunjung,Leibfarth, Frank A.,Woo, Sanghoon,Lee, Sumi,Kang, Minhyuk,Moon, Bongjin,Hawker, Craig J.,Bang, Joona WILEY‐VCH Verlag 2013 Advanced functional materials Vol.23 No.12

<P><B>Abstract</B></P><P>Balancing the interfacial interactions between a polymer and substrate is one of the most commonly employed methods to ensure the vertical orientation of nanodomains in block copolymer lithography. Although a number of technologies have been developed to meet this challenge, there remains a need for a universal solution for surface neutralization that combines simple synthesis, fast processing times, generality toward substrate, low density of film defects, and good surface adhesion. The chemistry of ketenes, which combines highly efficient polymer crosslinking through dimerization and surface adhesion through reaction with the substrate, is shown to be well suited to the challenge. The versatile chemistry of ketenes are accessed through the post‐polymerization of Meldrum's acid, which can be easily incorporated into copolymers through controlled radical polymerization processes. Further, the Meldrum's acid monomer is synthesized on a large scale in one step without the need for chromatography. Processing times of seconds, low defect density, simple synthetic procedures, and good substrate adhesion make these materials attractive as robust block copolymer neutralization layers.</P>

Combined epitaxial self-assembly of block copolymer lamellae on a hexagonal pre-pattern within microgrooves

Jung, Hyunjung,Woo, Sanghoon,Park, Sungmin,Lee, Sumi,Kang, Minhyuk,Choe, Youngson,Son, Jeong Gon,Ryu, Du Yeol,Huh, June,Bang, Joona The Royal Society of Chemistry 2015 SOFT MATTER Vol.11 No.21

<P>The directed self-assembly (DSA) of block copolymers (BCPs) has emerged as an alternative method to replace or complement conventional photolithography as a result of the approximately 10 nm scale of microdomain ordering, the variety of microstructures that can be obtained and its compatibility with current lithographic processes. In DSA, BCP microdomains are controlled <I>via</I> guide patterns and two main techniques are popular: graphoepitaxy and chemoepitaxy assembly. We have demonstrated a simple and feasible technology for a DSA process by combining graphoepitaxy with “inexpensive” chemoepitaxial assembly to improve the alignment of the lamellar microdomains. For chemoepitaxial assembly, the hexagonal surface patterns from cross-linkable, cylinder-forming BCP were used to guide the graphoepitaxial assembly of the overlying BCP lamellar film. When the guiding patterns were prepared on the hexagonal patterns, it was found that the degree of lamellar alignment was significantly improved compared with the lamellar alignment on the homogeneous neutral layers. Simulation results suggested that the underlying hexagonal pattern can assist the lamellar alignment by reducing the large number of orientation states of the lamellar layers. This strategy is applicable to various nanofabrication processes that require a high degree of fidelity in controlling the nanopatterns over large areas with reduced costs.</P> <P>Graphic Abstract</P><P>We demonstrated a simple and feasible technology for a DSA process by combining graphoepitaxy with “inexpensive” chemoepitaxial assembly to improve the alignment of lamellar microdomains. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c5sm00250h'> </P>

Nanoscopic Management of Molecular Packing and Orientation of Small Molecules by a Combination of Linear and Branched Alkyl Side Chains

Jung, Minwoo,Yoon, Youngwoon,Park, Jae Hoon,Cha, Wonsuk,Kim, Ajeong,Kang, Jinback,Gautam, Sanjeev,Seo, Dongkyun,Cho, Jeong Ho,Kim, Hyunjung,Choi, Jong Yong,Chae, Keun Hwa,Kwak, Kyungwon,Son, Hae Jung American Chemical Society 2014 ACS NANO Vol.8 No.6

<P>We synthesized a series of acceptor–donor–acceptor-type small molecules (SIDPP-EE, SIDPP-EO, SIDPP-OE, and SIDPP-OO) consisting of a dithienosilole (SI) electron-donating moiety and two diketopyrrolopyrrole (DPP) electron-withdrawing moieties each bearing linear <I>n</I>-octyl (O) and/or branched 2-ethylhexyl (E) alkyl side chains. X-ray diffraction patterns revealed that SIDPP-EE and SIDPP-EO films were highly crystalline with pronounced edge-on orientation, whereas SIDPP-OE and SIDPP-OO films were less crystalline with a radial distribution of molecular orientations. Near-edge X-ray absorption fine structure spectroscopy disclosed an edge-on orientation with a molecular backbone tilt angle of ∼22° for both SIDPP-EE and SIDPP-EO. Our analysis of the molecular packing and orientation indicated that the shorter 2-ethylhexyl groups on the SI core promote tight π–π stacking of the molecular backbone, whereas <I>n</I>-octyl groups on the SI core hinder close π–π stacking to some degree. Conversely, the longer linear <I>n</I>-octyl groups on the DPP arms facilitate close intermolecular packing <I>via</I> octyl–octyl interdigitation. Quantum mechanics/molecular mechanics molecular dynamics simulations determined the optimal three-dimensional positions of the flexible alkyl side chains of the SI and DPP units, which elucidates the structural cause of the molecular packing and orientation explicitly. The alkyl-chain-dependent molecular stacking significantly affected the electrical properties of the molecular films. The edge-on oriented molecules showed high hole mobilities in organic field-effect transistors, while the radially oriented molecules exhibited high photovoltaic properties in organic photovoltaic cells. These results demonstrate that appropriate positioning of alkyl side chains can modulate crystallinity and molecular orientation in SIDPP films, which ultimately have a profound impact on carrier transport and photovoltaic performance.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2014/ancac3.2014.8.issue-6/nn501133y/production/images/medium/nn-2014-01133y_0010.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn501133y'>ACS Electronic Supporting Info</A></P>

Activation of peroxisome proliferator-activated receptor δ (PPARδ) accelerates blastocyst hatching in mice

Jung Ah Yoon,Hee Jung Kang,Soo Jin Hwang,Hyunjung Lim,Haengseok Song 한국발생생물학회 2011 한국발생생물학회 학술발표대회 Vol.30 No.-

In particular, maternal prostacyclin (PGI2) is critical for embryo implantation and the action of PGI2 is not mediated via its G protein-coupled membrane receptor, IP, but its nuclear receptor, peroxisome proliferator-activated receptor δ (PPARδ). Recently, several studies have shown that PGI2 enhances blastocyst development and/or hatching rate in vitro, and subsequently implantation and live birth rates in mice. However, the mechanism by which PGI2 improves preimplantation embryo development in vitro remains unclear. Using molecular, pharmacologic and genetic approaches, we show that PGI2-induced PPARδ activation accelerates blastocyst hatching in mice. mRNAs for PPARδ, RXRs (heterodimeric partners of PPARδ) and PGI2 synthase are temporally induced after zygotic gene activation and their expression reaches maximum levels at the blastocyst stage, suggesting that functional complex of PPARδ can be formed in the blastocyst. Carbaprostacyclin (cPGI, a stable analogue of PGI2) and GW501516 (a PPARδ selective agonist) significantly accelerated blastocyst hatching but did not increase total cell number of cultured blastocysts. Whereas U51605 (a PGIS inhibitor) interfered with blastocyst hatching, GW501516 restored U51605-induced retarded hatching. In contrast to improvement of blastocyst hatching by PPARδ agonists, PPAR antagonists significantly inhibited blastocyst hatching. Furthermore, deletion of PPARδ at early stages of preimplantation mouse embryos caused delay of blastocyst hatching, but did not impair blastocyst development. Taken together, PGI2-induced PPARδ activation accelerates blastocyst hatching in mice.

Outbreak of Rice Blast Disease at Yeoju of Korea in 2020

Hyunjung Chung,Da Gyeong Jeong,Ji-Hyun Lee,In Jeong Kang,Hyeong-Kwon Shim,Chi Jung An,Joo Yeon Kim,Jung-Wook Yang 한국식물병리학회 2022 Plant Pathology Journal Vol.38 No.1

Rice blast is the most destructive disease threatening stable rice production in rice-growing areas. Cultiva- tion of disease-resistant rice cultivars is the most effec- tive way to control rice blast disease. However, the rice blast resistance is easy to breakdown within years by blast fungus that continually changes to adapt to new cultivars. Therefore, it is important to continuously monitor the incidence of rice blast disease and race differentiation of rice blast fungus in fields. In 2020, a severe rice blast disease occurred nationwide in Korea. We evaluated the incidence of rice blast disease in Yeo- ju and compared the weather conditions at the periods of rice blast disease in 2019 and 2020. We investigated the races and avirulence genes of rice blast isolates in Yeoju to identify race diversity and genetic character- istics of the isolates. This study will provide empirical support for rice blast control and the breeding of blast- resistant rice cultivars.

A Study of Effects of Nursing Ethics Education Based upon CEDA Academic Debate

Hyunjung Jung,Insun Jang,Hyunjoo Park 한국간호과학회 2011 한국간호과학회 학술대회 Vol.2011 No.10

Three-Dimensional Multilayered Nanostructures with Controlled Orientation of Microdomains from Cross-Linkable Block Copolymers

Jung, Hyunjung,Hwang, Dongjune,Kim, Eunhye,Kim, Byung-Jae,Lee, Won Bo,Poelma, Justin E.,Kim, Jihyun,Hawker, Craig J.,Huh, June,Ryu, Du Yeol,Bang, Joona American Chemical Society 2011 ACS NANO Vol.5 No.8

<P>Three-dimensional (3D) nanostructures were obtained by the directed formation of multilayer block copolymer (BCP) thin films. The initial step in this strategy involves the assembly and cross-linking of cylinder-forming polystyrene-<I>b</I>-poly(methyl methacrylate) (PS-<I>b</I>-PMMA) BCP, in which 1.5 mol % of reactive azido (−N<SUB>3</SUB>) groups were randomly incorporated along the styrene backbone. Significantly, assembly of thin films of lamellar-forming BCPs on top of the underlying cross-linked cylindrical layer exhibited perpendicular orientations of microdomains between lamellae and cylinder layers. From the theoretical calculation of free energy in the multilayers, it was found that the nematic interactions between polymer chains at the interface play a critical role in the perpendicular orientation of lamellae on the cross-linked cylinder layers. Removal of the PMMA domains then affords nonsymmetrical nanostructures which illustrate the promise of this strategy for the design of well-defined 3D nanotemplates. It was also demonstrated that this structure can be effectively used to enhance the light extraction efficiency of GaN light-emitting diodes. Furthermore, we anticipate that such 3D nanotemplates can be applied to various areas, including advanced BCP nanolithography and responsive surface coating.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2011/ancac3.2011.5.issue-8/nn2006943/production/images/medium/nn-2011-006943_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn2006943'>ACS Electronic Supporting Info</A></P>

The Study of Environmental Risk Assessment in Living Modified Silkworm (Bombyx mori)

Kim Hyunjung,Jongwoo Nam,Chuleui Jung,Tae Won Goo,Hoonbok Yi 한국응용곤충학회 2013 한국응용곤충학회 학술대회논문집 Vol.2013 No.10

It is true that the proper environmental risk assessments for many GM insects almost have not been executed in Korean research situation. Therefore, we tested the environmental risk assessment of GM silkworms if there is any difference between GM and non-GM silkworms by three. First, we measured their mobility in the breeding environment conditions with food and without food. Secondly, we measured their viability at the Korean artificial extreme environmental conditions (temperature, humidity, food) after escaping from their breeding environments. We observed the egg productivity and the hatchability between non-GM silkworm and transgenic silkworms with four different pair experiments. The mobility of non-GM silkworms and GM silkworms statistically did not differ and the egg production and hatchability was not also different. The hatchability by couple of GM female silkworm and non-GM male silkworm was lower than by non-GM male and female couple. We observed their viability (High Temp., wet and with food: p=0.0434; High Temp., wet and without food p=0.0430; High Temp., dry and with food: p=0.0005; High Temp., dry, without food: p=0.0479) between the GM silkworm and non-GM silkworm, and there was statistically different. Relatively, the viability of GM silkworm was lower than non-GM silkworms. We could not exactly test for viability of silkworm in low temperature conditions because of their hibernating. Although there was any difference in viability and hatchability between GM silkworm and non-GM silkworm, the all ability of GM silkworm was lower than non-GM silkworm. Conclusively, risk of GM silkworm was lower than non-GM silkworm.

Pt 나노입자의 탄소강 침적특성

정현준(Hyunjung JUNG),이인형(In Hyoung RHEE),강신영(Sin-young Kang),김영인(Young-in Kim) 한국산학기술학회 2014 한국산학기술학회 학술대회 Vol.- No.-

본 논문에서는 원자력발전소 2차 계통 수화학 조건에서 Pt 나노입자의 탄소강 침적특성을 조사하였 다. 원자력발전소 2차 계통은 탄소강 배관의 유체가속부식을 억제하기 위해 계통수의 pH 및 ECP와 같은 수화학 인자를 제어하고 있다. 하지만 지속적으로 유체가속부식은 발생하고 생성된 부식생성물은 증기발생기 내부로 유입되어 건전성을 훼손하고 있다. 따라서 본 연구에서는 Pt 나노입자를 이용하여 탄소강의 산화피막을 개질, 탄소강 배관의 유체가속부식을 억제하기 위해 Pt 나노입자의 탄소강 침적 특성을 조사하였다. 시험결과 Pt 나노입자는 탄소강 표면에 나노입자 크기를 유지하며, 균일하게 침적 되었다.

Upregulation of amyloid precursor protein by platelet-derived growth factor in hippocampal precursor cells :

Lim, Jung Su,Cho, Hyunjung,Hong, Hyun Seok,Kwon, Hyockman,Mook-Jung, Inhee,Kwon, Yunhee Kim Ovid Technologies (Wolters Kluwer) - Lippincott Wi 2007 NEUROREPORT - Vol.18 No.12

<P>Amyloid precursor protein generates the secreted amyloid precursor protein alpha, which protects hippocampal neurons from ischemic injury and facilitates neuronal survival and synaptogenesis in the developing nervous system. Here, we examined whether platelet-derived growth factor regulates the generation of secreted amyloid precursor protein alpha during the neuronal differentiation of hippocampal precursor cells, HiB5. We showed that platelet-derived growth factor promoted amyloid precursor protein production and secreted amyloid precursor protein alpha secretion. These effects of platelet-derived growth factor were diminished by the PI3K-specific inhibitor wortmannin and the protein kinase C-specific inhibitor GF109203X, suggesting the involvement of the PI3K and protein kinase C-signaling pathway. Furthermore, the conditioned media enriched with secreted amyloid precursor protein alpha promoted the survival of HiB5 cells during neuronal differentiation. These results suggest that the neurotrophic effect of platelet-derived growth factor is mediated in part via upregulation of the expression and release of secreted amyloid precursor protein alpha.</P>