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181.
Ju‐Myung Song Mohammad Luqman Joon‐Seop Kim Kwanwoo Shin 《Journal of Polymer Science.Polymer Physics》2007,45(9):1045-1052
The mechanical properties and morphology of homoblends of poly(ethyl acrylate‐co‐acrylate) (PEAA) having one ion pair per ionic monomer repeat unit and poly(ethyl acrylate‐co‐itaconate) (PEAITA) having two ion pairs were investigated. It was found that the compositional variation in the ionomer homoblends did not affect the matrix or cluster glass transition temperatures of the two ionomers of the homoblends. It was also observed that the ionomer homoblends showed two ionic plateaus and that the changes in the two ionic moduli were directly related to the relative amounts of the two ionomers. The ionic moduli calculated with the model for filler‐dispersed materials were found to fit the experimental data to a great extent. Therefore, it was suggested that the PEAITA/PEAA ionomer homoblends were filler‐containing composite materials rather than miscible blends. In the X‐ray scattering study, it was observed that the morphology of the ionomer homoblends was not affected by mixing. The results obtained in this work might be useful for the modification of the storage moduli of copolymers in a certain temperature range without the alteration of their processing temperatures. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1045–1052, 2007. 相似文献
182.
A Q2Q1 (quadratic velocity/linear pressure) finite element/level‐set method was proposed for simulating incompressible two‐phase flows with surface tension. The Navier–Stokes equations were solved using the Q2Q1 integrated FEM, and the level‐set variable was linearly interpolated using a ‘pseudo’ Q2Q1 finite element when calculating the density and viscosity of a fluid to avoid an unbounded density/viscosity. The advection of the level‐set function was calculated through the Taylor–Galerkin method, and the direct approach method is employed for reinitialization. The proposed method was tested by solving several benchmark problems including rising bubbles exhibiting a large density difference and the surface tension effect. The numerical results of the rising bubbles were compared with the existing results to validate the benchmark quantities such as the centroid, circularity, and rising velocity. Furthermore, we focused our attention mainly on mass conservation and time‐step. We observed that the present method represented a convergence rate between 1.0 and 1.5 orders in terms of mass conservation and provided more stable solutions even when using a larger time‐step than the critical time‐step that was imposed because of the explicit treatment of surface tension. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
183.
Mustafa Maria Duraisamy Navaneethan Kim Hyung Chan Hyeoun Myung Taek Choi Kyung Hyun 《Applied Physics A: Materials Science & Processing》2012,109(3):515-522
An effective method for the fabrication of thin film of single wall carbon nanotubes (SWCNT) using the electro-hydrodynamic atomization (EHDA) deposition technique was demonstrated. In this study, the SWCNT aqueous based dispersion ink was subjected to electrostatic atomization by using an EHDA deposition system. The ink flow visualization under the influence of electric field was performed and the operating EHDA parametric envelope of the ink was explored. Then the deposition of SWCNT through the EHDA process was carried out onto a metallic substrate at a fixed flow rate and corresponding applied voltage thereby achieving thickness ranging from ??70 to 130?nm by making multiple deposition passes. The microscopic inspection of the film was performed and thin film quality was examined by scanning electron microscope analysis. Finally, electrical behavior of the SWCNT film onto a metallic substrate through temperature dependent current-voltage measurements was investigated. The SWCNT film deposited onto the metallic substrate showed electrical conductivity of ??2.98?S/cm. 相似文献
184.
Jae‐Hong Lim Nopparat Phiboolsirichit Syed Mubeen Youngwoo Rheem MarcA. Deshusses Ashok Mulchandani NosangV Myung 《Electroanalysis》2010,22(1):99-105
The electrical transport and NH3 sensing properties of randomly oriented and aligned SWNT networks were presented and discussed. The results indicate that aligned SWNT‐FETs have better FET characteristics due to the reduced number of interconnected nodes. This was particularly true as the resistance of the devices increased. Gated electrical breakdown was implemented to selectively remove metallic (m‐) SWNTs, thereby reducing scattering centers. This technique provided significant improvements in FET characteristics resulting in greater on/off ratio (e.g. 104). AC dielectrophoretic alignment followed by selective electrical breakdown of m‐SWNTs can significantly enhance the semiconducting properties of SWNT networks which resulted in highly sensitive sensors. 相似文献
185.
Jeong Hee Moon So Hee Yoon Yong Jin Bae Myung Soo Kim 《Journal of the American Society for Mass Spectrometry》2010,21(7):1151-1158
The yields of post-source decay (PSD) and time-resolved photodissociation (PD) at 193 and 266 nm were measured for singly
protonated leucine enkephalin ([YGGFL + H]+), a benchmark in the study of peptide ion dissociation, by using tandem time-of-flight mass spectrometry. The peptide ion
was generated by matrix-assisted laser desorption ionization (MALDI) using 2,5-dihydroxybenzoic acid as the matrix. The critical
energy (E0) and entropy (ΔS‡ at 1000 K) for the dissociation were determined by Rice-Ramsperger-Kassel-Marcus fit of the experimental
data. MALDI was done for a mixture of YGGFL and Y6 and the plume temperature determined by the kinetic analysis of [Y6 + H]+ data were used to improve the precision of E0 and ΔS‡ for [YGGFL + H]+. E0 and ΔS‡ thus determined (E0 = 0.67 ± 0.08 eV, ΔS‡=−24.4 ± 3.2 eu with 1 eu = 4.184 J K−1mol−1) were significantly different from those determined by blackbody infrared radiative dissociation (BIRD) (E0 = 1.10 eV, ΔS‡ = −14.9 eu), and by surface-induced dissociation (SID) (E0 = 1.13 eV, ΔS‡ = −10.3 eu). Analysis of the present experimental data with the SID kinetics (and BIRD kinetics also) led
to an unrealistic situation where not only PSD and PD but also MALDI-TOF signals could not be detected. As an explanation
for the discrepancy, it was suggested that transition-state switching occurs from an energy bottleneck (SID/BIRD) to an entropy
bottleneck (PSD/PD) as the internal energy increases. 相似文献
186.
We investigate the Lifshitz black holes from the Ho?ava–Lifshitz gravity by comparing with the Lifshitz black hole from the 3D new massive gravity. We note that these solutions all have single horizons. These black holes are very similar to each other when studying their thermodynamics. It is shown that a second order phase transition is unlikely possible to occur between z=3,2 Lifshitz black holes and z=1 Ho?ava black hole. 相似文献
187.
Hee Jung Choi Hwan Sun Cho Sang Cheol Han Myung Ho Hyun 《Journal of separation science》2009,32(4):536-541
A residual silanol group‐protecting chiral stationary phase (CSP) based on optically active (3,3′‐diphenyl‐1,1′‐binaphthyl)‐20‐crown‐6 was successfully applied to the resolution of fluoroquinolone compounds including gemifloxacin mesylate. The chiral recognition ability of the residual silanol group‐protecting CSP was generally greater than that of the residual silanol group‐containing CSP. From these results, it was concluded that the simple protection of the residual silanol groups of the latter CSP with lipophilic n‐octyl groups can improve its chiral recognition ability for the resolution of racemic fluoroquinolone compounds. The chromatographic resolution behaviors were investigated as a function of the content and type of organic and acidic modifiers and the ammonium acetate concentration in aqueous mobile phase and the column temperature. Especially, the addition of ammonium acetate to the mobile phase was found to be a quite effective means of reducing the enantiomer retentions without sacrificing the chiral recognition efficiency of the CSP. 相似文献
188.
Chuan-Ling Si Yu Zhang Zhen-Yuan Zhu Jie Xu Jin-Kyu Kim Young-Soo Bae 《Chemistry of Natural Compounds》2009,45(6):814-816
A new secoiridoid glucoside, oleuropein-4″-methyl ether, was isolated, together with two known secoiridoid glucosides, ligstroside
and oleuropein, from the leaves of Fraxinus rhynchophylla Hance by repeated column chromatography over Sephadex LH-20. The structure of the new compound has been characterized on
the basis of spectroscopic evidence. 相似文献
189.
One-photon mass-analyzed threshold ionization (MATI) spectrum of trans-C(2)H(2)Cl(2) was obtained by using vacuum ultraviolet radiation generated by four-wave mixing in Kr. The ionization energy determined from the position of the 0-0 band in the spectrum was 9.6306 +/- 0.0006 eV. Ten vibrational fundamentals for the cation were identified. The spectrum also displayed abundant overtones and combinations, most of which could be assigned adequately by comparing with the quantum chemical results. It was found that channel interaction was not important for this system. The equilibrium geometry of the cation was estimated through the Franck-Condon fit. 相似文献
190.
Choi YS Kim YK Shim JH Kim EM Kang HS Yoon do Y Muneta Y Myung PK 《Experimental & molecular medicine》2006,38(5):574-582
Xenotransplantation, the transplantation of cells, tissues or organs between individuals of different species, would resolve the current shortage of organs, but rejection remains the major hurdle to successful xenotransplantation. In the present study, we analyzed mixed lymphocyte reactions (MLRs) and used 51Cr release assays in order to identify the proliferation and expansion of mouse CD8+ cytotoxic T lymphocyte cells against PK15, PK15/pIL-18 or PK15/mIL-18 cells. In addition, we identified T cell populations in mouse splenocytes and lymph node cells using two-color flow cytometry. It was found that the CD8+ T cells of xenograft recipients proliferated extensively and that the survival rates of populations of PK15/mIL-18 or PK15/pIL-18 cells were higher than untransfected controls. Moreover, CD3+ T cells were increased in mice injected with PK15 cells or PK15/pIL-18 cells but PK15/pIL-18 cell numbers were lower in lymph nodes than untransfected controls. CD8+ T cells numbers were reduced in the lymph nodes of PK15/pIL-18 injected mice. These results suggest that porcine IL-18 regulates anti-pig cellular rejection in C57BL/6 mice. 相似文献