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Sun-Joo Hong,D. E. Holmes,L. H. Piette. Korean Chemical Society 1971 대한화학회지 Vol.15 No.5
An ESR study has been made on free radicals produced in frozen aqueous solutions (ices) of glycine, DL-${\alpha}$-alanine, DL-serine, L-cysteine, DL-leucine and DL-isoleucine by gamma-irradiation at dry ice temperature. All free radicals induced were decayed concomitant to the successive annealing but the radical species which is believed to be dominant seems to be stable even near the melting point of the ice. These dominant species were found to be identical to those resulted from direct action of radiation in the solid at room temperature. Small but significant changes in the spectra of glycine and DL-${\alpha}$-alanine were observed by varying the microwave power. These results seem to support the view that the spectra obtained were composite consisting of more than two different resonances having different power saturation characteristics. The relative contribution of unidentified resonances to the composite spectra was greater for solutions of low concentration. These resonances are assumed to be induced by indirect effects, mainly hydrogen abstraction by radiation produced hydroxyl radicals and also C-N bond cleavage by hydrated electrons.
Jeong, Kwang-Un,Jang, Ji-Hyun,Kim, Dae-Yoon,Nah, Changwoon,Lee, Joong Hee,Lee, Myong-Hoon,Sun, Hao-Jan,Wang, Chien-Lung,Cheng, Stephen Z. D.,Thomas, Edwin L. Royal Society of Chemistry 2011 Journal of materials chemistry Vol.21 No.19
<P>Combining the physical principle of actuators with the basic concept of photonic crystals, colour-tunable three-dimensional (3D) photonic actuators were successfully fabricated. By controlling the <I>d</I>-spacings and the refractive index contrasts of the self-assembled 3D colloidal photonic crystals, colours of the photonic actuators were tuned. Various shapes of these 3D actuating objects were constructed by transforming the programmed 2D structures <I>via</I> bending, twisting and folding mechanisms. These 2D structures were first programmed by breaking the symmetry. The selective swellings were then applied as driving forces to control the shapes and colours of the photonic actuators. Scroll photonic actuators had been first demonstrated by bending the traditional 2D cantilever structure (K.-U. Jeong, <I>et al.</I>, <I>J.</I><I>Mater.</I><I>Chem.</I>, 2009, <B>19</B>, 1956). By breaking the symmetry of a cantilever structure perpendicular to its long axis, polypeptide-/DNA-like 3D helical photonic actuators were obtained from the programmed 2D structure <I>via</I> twisting processes. Both left- and right-handed scrolls and helices with various colours can be achieved by changing the polarity of solvents. Different types of 3D actuators, such as cube, pyramid and phlat ball, were also demonstrated <I>via</I> the folding mechanism. The reversible 3D photonic actuators transformed from the programmed 2D structures <I>via</I> the bending, twisting and folding mechanisms may be applied in the field of mechanical actuators, and optoelectronic and bio-mimetic devices.</P> <P>Graphic Abstract</P><P>Reversible colour and shape tunable photonic actuators were constructed by transforming the programmed 2D structures to the 3D objects <I>via</I> bending, twisting and folding mechanisms. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0jm03631e'> </P>
Sun, Y.,Ma, L.,Han, D.,Du, L.,Qi, F.,Zhang, W.,Sun, J.,Huang, S.,Kim, E. S.,Li, S. SPRINGER 2017 Journal of industrial microbiology & biotechnology Vol.44 No.2
<P>The cytochrome P450 enzymes (CYPs) CYP-sb21 from Sebekia benihana and CYP-pa1 from Pseudonocardia autotrophica are able to hydroxylate the immunosuppressant cyclosporin A (CsA) in a regioselective manner, giving rise to the production of two hair-stimulating agents (with dramatically attenuated immunosuppressant activity), gamma-hydroxy-N-methyl-l-Leu4-CsA (CsA-4-OH) and gamma-hydroxy-N-methyl-l-Leu9-CsA (CsA-9-OH). Recently, the in vitro activity of CYP-sb21 was identified using several surrogate redox partner proteins. Herein, we reconstituted the in vitro activity of CYP-pa1 for the first time via a similar strategy. Moreover, the supporting activities of a set of ferredoxin (Fdx)/ferredoxin reductase (FdR) pairs from the cyanobacterium Synechococcus elongatus PCC 7942 were comparatively analyzed to identify the optimal redox systems for these two CsA hydroxylases. The results suggest the great value of cyanobacterial redox partner proteins for both academic research and industrial application of P450 biocatalysts.</P>
Insulin Inhibits the Expression of Adiponectin and AdipoR2 mRNA in Cultured Bovine Adipocytes
Sun, Y.G.,Zan, L.S.,Wang, H.B.,Guo, H.F.,Yang, D.P.,Zhao, X.L.,Gui, L.S. Asian Australasian Association of Animal Productio 2009 Animal Bioscience Vol.22 No.10
Adiponectin is an adipocyte-derived protein that has a regulatory role in energy homeostasis and influences insulin sensitivity. Its effects on glucose utilization and lipid metabolism are mediated by AdipoR1 and AdipoR2. How insulin affects adiponectin gene expression and secretion is still controversial. This study was conducted to determine the expression of adiponectin, AdipRs and $PPAR-\gamma$ during the differentiation of bovine preadipocytes and the effect of insulin on expression of these genes in bovine adipocytes. The bovine preadipocytes started to accumulate lipids three days after differentiation was induced, with increased expression of adiponectin, AdipoR2 and $PPAR-\gamma$ mRNAs. Insulin decreased the expression of adiponectin mRNA in a dose- and time-dependent fashion, and the inhibition was detectable at insulin concentrations as low as 10 nM and as early as 2 h after addition of 100 nM insulin. Insulin also inhibited the expression of AdipoR2 mRNA at concentrations from 1 to 1,000 nM or 24 h after addition of 100 nM insulin, but did not affect the expression of AdipoR1 in bovine adipocytes. Inhibition of PI3K with LY294002 reversed the inhibition of adiponectin and AdipoR2 mRNA expression by insulin. These results suggest that insulin suppresses the expression of adiponectin and AdipoR2 at least partially via the PI3K signal pathway.
Cellobiose Hydrolysis Using Acid-functionalized Nanoparticles
L. Peña,M. Ikenberry,B. Ware,K. L. Hohn,D. Boyle,X. S. Sun,D. Wang 한국생물공학회 2011 Biotechnology and Bioprocess Engineering Vol.16 No.6
Mineral acids have been used effectively for the pretreatment of cellulosic biomass to improve sugar recovery and promote its conversion to ethanol; however,substantial capital investment is required to enable separation of the acid, and corrosion-resistant materials are necessary. Disposal and neutralization costs are also concerns because they can decrease the economic feasibility of the process. In this work, three acid-functionalized nanoparticles were synthesized for pretreatment and hydrolysis of lignocellulosic biomass. Silica-protected cobalt spinel ferrite nanoparticles were functionalized with perfluoroalkylsulfonic acid (PFS), alkylsulfonic acid (AS), and butylcarboxylic acid (BCOOH) groups. These nanoparticles were magnetically separated from the reaction media and reused. TEM images showed that the average diameter was 2 nm for both PFS and BCOOH nanoparticles and 7 nm for AS nanoparticles. FTIR confirmed the presence of sulfonic and carboxylic acid functional groups. Ion exchange titration measurements yielded 0.9, 1.7, and 0.2mmol H+/g of catalyst for PFS, AS, and BCOOH nanoparticles,respectively. Elemental analysis results indicated that PFS and AS nanoparticles had 3.1 and 4.9% sulfur,respectively. Cellobiose hydrolysis was used as a model reaction to evaluate the performance of acid-functionalized magnetic nanoparticles for breaking β-(1→4) glycosidic bonds. Cellobiose conversion of 78% was achieved when using AS nanoparticles as the catalyst at 175°C for 1 h,which was significantly higher than the conversion for the control experiment (52%). AS nanoparticles retained more than 60% of their sulfonic acids groups after the first run,and 65 and 60% conversions were obtained for the second and third runs, respectively.
Gradual electroforming and memristive switching in Pt/CuO<sub><i>x</i></sub>/Si/Pt systems
Wei, L L,Shang, D S,Sun, J R,Lee, S B,Sun, Z G,Shen, B G IOP Pub 2013 Nanotechnology Vol.24 No.32
<P>We report a memristive switching effect in Pt/CuO<SUB><I>x</I></SUB>/Si/Pt devices prepared by the rf sputtering technique at room temperature. Differently from other Cu-based metal filament switching systems, a gradual electroforming process, marked by a gradual increase of the device resistance and a gradual decrease of the device capacitance, was observed in the current–voltage and capacitance characteristics. After the gradual electroforming, the devices show a uniform memristive switching behavior. By Auger electron spectroscopy analysis, a model based on the thickness change of the SiO<SUB><I>x</I></SUB> layer at the CuO<SUB><I>x</I></SUB>/Si interface and Cu ion migration is proposed for the gradual electroforming and uniform memristive switching, respectively. This work should be meaningful for the preparation of forming-free and homogeneous memristive devices.</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.
Solidification and Evolution of β-NiAl Phase in a Re-Containing Single Crystal Superalloy
Y. M. Li,X. G. Wang,Z. H. Tan,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.10
The β-NiAl phase, which may exacerbate the high-temperature mechanical properties of Ni-based superalloy, was observedin a designed Re-containing single crystal superalloy. The solidification mechanism of β-NiAl phase and its evolutionafter solution treatment as well as long-term aging at 1120 °C were systematically investigated. The β-NiAl phase wasconfirmed by the analyses of XRD and TEM in as-cast specimen. Combined the analyses of TEM, DSC, phase diagramsand chemical segregation behaviors obtained via EPMA, the solidification path in interdendritic region was determined asL → (β-NiAl + Cr) eutectic, L → β + δ, L + β → γ′, L → γ′. The β-NiAl phase could be diminished by solution treatment and/or long-term aging treatment. After the solution treatment at 1330 °C for 30 min, the β-NiAl phase split into small bulks andthe δ phase dissolved, contributing to the formation of the γ + γ′ structure and large blocky δ phase. During the long-termaging at the 1120 °C, the β-NiAl phase transformed into γ and γ′ phase. With aging time prolonging, the Cr-rich phase dissolved,which promoted the precipitation of TCP confirmed as μ phase with three morphologies.