Self-standing and shape-memorable UV-curing epoxy polymers for three-dimensional (3D) continuous-filament printing

Sun, H.,Kim, Y.,Kim, Y. C.,Park, I. K.,Suhr, J.,Byun, D.,Choi, H. R.,Kuk, K.,Baek, O. H.,Jung, Y. K.,Choi, H. J.,Kim, K. J.,Nam, J. D. The Royal Society of Chemistry 2018 Journal of materials chemistry. C, Materials for o Vol.6 No.12

<P>In the development of three-dimensional printable materials for high-speed and high-resolution printing, UV-curing polymers can guarantee fast and precise printing of high performance load-bearing structures, but the injected drops of the monomers tend to spread over the substrates due to their low viscosity. In this study, we imposed the self-standing and shape-memorable capability of an epoxy acrylate (EA) monomer to ensure continuous filamentary 3D printing while maintaining its low viscosity nature. Using octadecanamide (ODA) with EA, strong hydrogen-bond networks (−N−H⋯OC−, −N−CO⋯H-O-, -N-H⋯N-) were additionally achieved in the material system and the developed material distinctively exhibited rheological duality at different processing stages: a low-viscosity liquid-like behavior (viscosity of ∼50 Pa) while passing through the nozzle and a self-standing solid-like behavior (static yield stress of ∼364 Pa) right after being printed. This reversible liquid-to-solid transitional capability was quantified by viscoelastic complex moduli provided a dynamic yield stress (<I>τ</I>y,G) of 210 Pa corresponding to the upright stacking up to ∼3.2 cm (3 wt% of ODA). The time (<I>t</I>y,G) required for conformational rearrangement was evaluated to be as fast as ∼10<SUP>−2</SUP> s. After UV curing, the 3D printed layers exhibited no air pockets or weld lines at the stacked interfaces, which could guarantee excellent mechanical performance and structural integrity.</P>

Ginsenoside Rb1에 의한 발암유전자 ras의 활성 억제

이선주,전병학 대한암예방학회 2003 Journal of cancer prevention Vol.8 No.2

Distinct clinical courses according to presenting phenotypes and their correlations to <i>ATP7B</i> mutations in a large Wilson's disease cohort

Lee, Beom H.,Kim, Joo H.,Lee, Sun Y.,Jin, Hye Y.,Kim, Kwi‐,Joo,Lee, Jin‐,Joo,Park, Jung‐,Young,Kim, Gu‐,Hwan,Choi, Jin‐,Ho,Kim, Kyung M.,Yoo, Han‐,Wook Blackwell Publishing Ltd 2011 Liver International Vol.31 No.6

<P><B>Abstract</B></P><P><B>Introduction and aims: </B> Wide phenotypic and genotypic heterogeneities in Wilson's disease (WD) have been reported, hampering the study of their correlations. The goal of this study was to identify the factors related to these diversities.</P><P><B>Methods: </B> Clinical courses and molecular genetic characteristics were analysed in 237 unrelated Korean WD families. The average follow‐up period was 8.2 ± 5.8 years.</P><P><B>Results: </B> Presenting phenotypes were classified as H1 (12.2%), H2 (42.4%), N1 (21.6%), N2 (0.4%), NX (0.4%), presymptomatic (22.4%) and other (0.4%), modifying the guidelines by Ferenci and colleagues. Age at presentation was youngest and cirrhosis was rarest in the presymptomatic group. Decompensated cirrhosis was the highest in the H1 group. Favourable outcome was rarest in the N1 group. Forty‐seven (11 novel) <I>ATP7B</I> mutations were identified in 85% of the 474 alleles. Multiplex ligation‐dependent probe amplification assays in <I>ATP7B</I> and analyses of <I>ATOX1</I> and <I>COMMD1</I> genes identified no additional mutations. Yeast complementation assays demonstrated functional perturbation of the seven novel missense mutants. Five major mutations, p.Arg778Leu, p.Ala874Val, p.Asn1270Ser, p.Lys838SerfsX35 and p.Leu1083Phe, accounted for 63% of the alleles. H1 was more common, age at presentation was younger and N1+N2+NX tended to be less common in patients with nonsense, frame shifting or splicing mutations than in those with missense mutations alone. Patients with both mutations in the transduction (Td) or the ATP hinge domain showed presymptomatic or hepatic manifestations but no neurological manifestation.</P><P><B>Conclusions: </B> The presenting phenotype strongly affects the clinical outcome of WD, and is related to the <I>ATP7B</I> mutation type and location, providing an evidence for genotype–phenotype correlations in WD.</P>

China Spallation Neutron Source: Accelerator Design Iterations and R&D Status

J. Wei,C.-D. Deng,C.-H. Wang,C.-T. Shi,H. Sun,H.-F. Ouyang,H.-M. Qu,H.-Y. Dong,J. Li,J. Zhang,J.-S. Cao,J.-Y. Tang,L. Dong,L.-L. Wang,Q. Qin,Q.-B. Wang,S. Wang,S.-N. Fu,S.-X Fang,T. -G. Xu,W. Kang,Y.- 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.I

The China Spallation Neutron Source (CSNS) is a high-power, accelerator-based project currently under preparation. The accelerator complex consists of an H$^-$ ion source, an H$^-$ linac, a rapid-cycling proton synchrotron, and the transport lines. During the past year, the design of most accelerator systems went through major iterations, and initial research and developments was started on the prototyping of several key components.

H2O2 에 의해 생성된 myoglobi 자유라디칼에 대한 ESR 연구

홍순주,Lawrence H . Piette ( Sun Joo Hong,Lawrence H . Piette ) 생화학분자생물학회 1989 BMB Reports Vol.22 No.2

Metmyoglobin when incubated with hydrogen peroxide in the presence of the spin trap, 5,5-dimethyl pyrroline-N-oxide (DMPO) has produced an asymmetric ESR spectrum, consisting of five broad lines of different intensities, in which no evidence of DMPO/OH radical adduct was detected. This result was found to be consistent to other incubation in which metmyoglobin was mixed with Fenton`s reagent in the presence of DMPO. Furthermore, DMPO/OH radical adducts validated by the characteristic ESR quartet while incubating Fenton`s reagent with DMPO, disappeared completely and was displaced by the asymmetric broad five line signal immediately after addition of metmyoglobin to this incubation solution. These results strongly suggest that not only both of the primary and secondary radical species formed in the vicinity of the heme active site and hence trapped by DMPO, but also additional DMPO/OH radical adducts formed on the surface of the protein molecule by Fenton`s reagent/DMPO incubation are together strongly immobilized in the heme pocket of the myoglobin molecule. A similar incubation in which metmyoglobin was mixed with hydrogen peroxide in the presence of the spin trap 3,3,5,5-tetramethyl-1-pyrroline-N-oxide (TMPO), however, gave a quite different ESR spectrum with two different signal species, a sharp triplet of equal intensities with a parameter a_N 6.8 G, and a broad, structureless signal covering about 40 G. This indicates that the TMPO, having two more substituents, traps radicals formed on the surface of the protein molecule, in contrast to DMPO, due to the increased steric hindrance and hence can hardly enter into the heme pocket. The broad signal species was ascribed to the TMPO radical adduct formed with α-carbon atom in backbone and the triplet to that formed with side chains.

Million-Fold Electrical Conductivity Enhancement in Fe ₂ (DEBDC) versus Mn ₂ (DEBDC) (E = S, O)

Sun, Lei,Hendon, Christopher H.,Minier, Mikael A.,Walsh, Aron,Dincă,, Mircea American Chemical Society 2015 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.137 No.19

<P/><P>Reaction of FeCl<SUB>2</SUB> and H<SUB>4</SUB>DSBDC (2,5-disulfhydrylbenzene-1,4-dicarboxylic acid) leads to the formation of Fe<SUB>2</SUB>(D<B>S</B>BDC), an analogue of M<SUB>2</SUB>(D<B>O</B>BDC) (MOF-74, DOBDC<SUP>4–</SUP> = 2,5-dihydroxybenzene-1,4-dicarboxylate). The bulk electrical conductivity values of both Fe<SUB>2</SUB>(D<B>S</B>BDC) and Fe<SUB>2</SUB>(D<B>O</B>BDC) are ∼6 orders of magnitude higher than those of the Mn<SUP>2+</SUP> analogues, Mn<SUB>2</SUB>(DEBDC) (E = O, S). Because the metals are of the same formal oxidation state, the increase in conductivity is attributed to the loosely bound Fe<SUP>2+</SUP> β-spin electron. These results provide important insight for the rational design of conductive metal–organic frameworks, highlighting in particular the advantages of iron for synthesizing such materials.</P>

Major Sensing Proteins in Pathogenic Fungi: The Hybrid Histidine Kinase Family

Hé,rivaux, Anaï,s,So, Yee-Seul,Gastebois, Amandine,Latgé,, Jean-Paul,Bouchara, Jean-Philippe,Bahn, Yong-Sun,Papon, Nicolas Public Library of Science 2016 PLoS pathogens Vol.12 No.7

Covalent attachment of chiral alkaloids onto silicon surfaces

H. Wang,H.L. Zhang,Y. Guo,F.Y. Qiao,Q.Y. Sun 한국물리학회 2007 Current Applied Physics Vol.7 No.s1

In this work, we report the covalent attachment of a chiral molecule onto a hydrogen-terminated Si(SiH) surface by using an extre-mely mild approach. Cinchonine, a chiral alkaloid was self-assembled onto a SiH surface via a photochemistry method at room tem-perature. The self-assembled monolayers (SAMs) obtained were characterized by means of ellipsometry, XPS and wettability studies.The lm formation kinetics was monitored by ellipsometry and XPS, which indicated that a full monolayer was formed within 15 h.

Dietary Foeniculum vulgare Mill extract attenuated UVB irradiation-induced skin photoaging by activating of Nrf2 and inhibiting MAPK pathways

Sun, Z.,Park, S.Y.,Hwang, E.,Park, B.,Seo, S.A.,Cho, J.G.,Zhang, M.,Yi, T.H. G. Fischer 2016 Phytomedicine Vol.23 No.12

<P>Background: Foeniculum vulgare Mill (FV) has long been prescribed in traditional medicine due to its antioxidant anti-inflammatory properties. However, little research has been done on the use of FV to alleviate changes in UVB-induced photoaging Purpose: This study was to investigate the photoprotective effects and mechanism of FV in vitro and in vivo. Methods: The anti-photoaging effect of FV was assessed in normal human dermal fibroblasts (NHDFs) in vitro. The secretion of reactive oxygen species (ROS), lactate dehydrogenase (LDH), GSH, matrix metalloproteinases (MMPs), procollagen type I, IL-6 and transforming growth factor-beta 1 (TGF-beta 1) were measured by kits. Additionally, the level of nuclear factor (erythroid-derived 2)-like 2 (Nrf2), p-ERK and p38 were evaluated by western blotting. In vivo, H&E and Masson's trichrome staining were employed. The expression of MMP-1, procollagen type I, TGF-beta 1 and elastin were measured by western blot. Results: FV significantly increased the production of collagen, elastin and TGF-beta 1 levels, while blocked matrix metalloproteinases (MMPs) production in UVB irradiation induced hairless mice, which were consistent with the result in NHDFs. Furthermore, FV dose-dependently decreased the production of ROS and LDH by promoting the nuclear amount of Nrf2 and enhancing the expression of cytoprotective antioxidants such as GSH. FV also significantly quenched UVB-induced phosphorylation of ERK and p38 in NHDFs. Conclusion: Our results indicate that FV is a potential botanical agent for the treatment of skin damage induced by UV irradiation. (C) 2016 Elsevier GmbH. All rights reserved.</P>

Microstructural Stability and Creep Performance of a Novel Low-Cost Single Crystal Superalloy

Z. H. Tan,X. G. Wang,Y. L. Du,Y. M. Li,Y. H. Yang,J. L. Liu,J. D. Liu,J. G. Li,Y. Z. Zhou,X. F. Sun 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.7

The increasing pursuit of advanced aero-engines with lower ratio between the cost and performance has greatly promotedthe demanding of single crystal superalloys characterized by low cost and outstanding temperature capability. In this study,a novel low-cost single crystal superalloy was designed and the creep tests as well as micro-characterization were carried outon the experimental alloy. The results illustrated that the novel single crystal alloy exhibited an ideal microstructural stabilitywithout precipitating TCP phases, after long-term thermal exposure at the ultimate service temperature of third generationsingle crystal superalloys. Moreover, the experimental alloy with only 3 wt% Re addition demonstrated remarkable creepresistance and maintained a very low minimum creep rate at 1100 °C/137 MPa and 1120 °C/137 MPa, while the accumulationand coalescence of micro-pores had eventually led to the alloy fracture. Apart from that, the compact interfacial dislocationnetworks the 2nd γ′ phase were observed after high-temperature creep rupture, and the typical a < 010 > superdislocationswith relatively poor mobility was found at 1120 °C. At 760 °C/800 MPa, both the minimum creep velocity and entire creepstain was increased evidently, however, the ultimate creep rupture life of the alloy had still reached 200 h. The correspondingdeformation mechanism was identified as the combination of superdislocation pairs shearing and a/3 < 121 > partial dislocationcutting the γ′ phase with a SISF being generated. In general, the novel single crystal alloy characterized by remarkablemechanical properties and cost reduction possesses a great potential for future application in the advanced aircraft engines.