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31.
Kyung Hwa Hong Jong Lyoul Park In Hwan Sul Ji Ho Youk Tae Jin Kang 《Journal of Polymer Science.Polymer Physics》2006,44(17):2468-2474
Polyvinyl alcohol (PVA) nanofibers containing Ag nanoparticles were prepared by electrospinning PVA/silver nitrate (AgNO3) aqueous solutions, followed by short heat treatment, and their antimicrobial activity was investigated for wound dressing applications. Since PVA is a water soluble and biocompatible polymer, it is one of the best materials for the preparation of wound dressing nanofibers. After heat treatment at 155 °C for 3 min, the PVA/AgNO3 nanofibers became insoluble, while the Ag+ ions therein were reduced so as to produce a large number of Ag nanoparticles situated preferentially on their surface. The residual Ag+ ions were reduced by subsequent UV irradiation for 3 h. The average diameter of the Ag nanoparticles after the heat treatment was 5.9 nm and this value increased slightly to 6.3 nm after UV irradiation. It was found that most of the Ag+ ions were reduced by the simple heat treatment. The PVA nanofibers containing Ag nanoparticles showed very strong antimicrobial activity. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2468–2474, 2006 相似文献
32.
S. Park T. U. Kampen T. Kachel P. Bressler W. Braun D. R. T. Zahn 《Applied Surface Science》2002,190(1-4):376-381
The interaction of Ag and In with a thin film of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) was studied by near-edge X-ray absorption fine structure (NEXAFS). Upon Ag deposition on a PTCDA film of 20 nm thickness the relative intensities and lineshapes, as well as the angular dependence of the spectra remains unchanged, illustrating the formation of a chemically unreactive Ag/PTCDA interface. On the other hand, the adsorption of 0.3 nm In strongly decreases the intensity of the π* resonances in C and O K-edge NEXAFS spectra. This is attributed to a strong charge transfer between In and PTCDA, leading to a redistribution of the charge in the molecule. However, the absence of a strong shift or new features and negligible dependence of peak intensities corresponding to π* resonances on the In thickness indicate that the interaction between In and PTCDA is not accompanied by a covalent bond formation. 相似文献
33.
In this paper, the nonfragile control problem for synchronization of a class of chaotic dynamical systems with controller gain variations is studied. Using the Lyapunov method and LMI (linear matrix inequality) technique, a criterion for the existence of the nonfragile controller for synchronization is derived in terms of LMI. To show the effectiveness of the proposed method, the control problem is applied to Genesio chaotic system. 相似文献
34.
D. P. Kozlenko S. E. Kichanov S. Lee J. -G. Park V. P. Glazkov B. N. Savenko 《JETP Letters》2006,83(8):346-350
The effect of a high pressure (up to 6 GPa) on the crystal and magnetic structure of the hexagonal manganite LuMnO3 is studied by neutron diffraction in the temperature range 10–295 K. It is found that, as the pressure increases, the ordered magnetic moment of Mn ions at T = 10 K decreases noticeably from 2.48 (0 GPa) to 1.98 μB (6 GPa). This decrease is due to an enhancement of the geometrical frustration effects on the triangular lattice. At the same time, the symmetry of the triangular antiferromagnetic state (the irreducible representation Γ2) remains unchanged. A correlation is revealed between the distortion parameter of the triangular lattice formed by Mn ions and the symmetry of the antiferromagnetic state of hexagonal manganites RMnO3. Based on this correlation, a generalized magnetic phase diagram of these compounds is constructed. The obtained phase diagram provides an explanation for the changes observed in the magnetic state of hexagonal manganites caused by high pressure and chemical substitution. 相似文献
35.
几种陆用惯性自寻北方案的比较 总被引:2,自引:1,他引:1
介绍几种目前广泛应用于军事及民用工业领域的高精度自寻北方案,同时讨论并分析了这些方案的精度和误差补偿方法,提出在兵器领域尤其是在陆用车辆上的适用性等问题。 相似文献
36.
Shuguan Ji Zhenxin Liu Shaoyun Shi 《Journal of Mathematical Analysis and Applications》2007,325(2):1306-1313
The method of equivalent variational methods, originally due to Carathéodory for free problems in the calculus of variations is extended to investigate boundary value problems for a class of second order differential equations on the half-line. Some applications are presented to illustrate the potential of this method. 相似文献
37.
The validity of local parton-hadron duality within the framework of HERWIG and JETSET event generators is investigated. We concentrate one
+
e
– annihilations in LEP 2 energy range as these interactions provide theoretically the cleanest condition for the discussion of this concept. We conclude that the concept of local parton-hadron duality is not valid in either of the two generators considered. 相似文献
38.
The laser cladding of Fe-based alloys on a medium carbon steel substrate was performed using a CO2 laser and Ar shielding gas that was blown into a molten pool. The microstructure and cracking susceptibility of the laser-clad layers were studied in terms of carbon additions. Results show that the small change of the carbon content in the alloy powders can obviously change the microstructure and properties of the layers. When the carbon content is in the range of 0.3–0.4 wt.%, the decrease of the carbon content in alloy powders will increase the hardness and toughness of the layers simultaneously under the same process parameters. As a result, crack-free coatings with high hardness can be obtained. As the carbon content increases from 0.2 wt.% to 0.4 wt.%, the segregation ratio of chromium increases, while the segregation ratios of nickel, manganese, and silicon first decrease and then increase. At the same time, a new designing principle concerning the composition and microstructure has been put forward, and the principal mechanisms of strengthening and toughening of the layers are fine-grain strengthening and low carbon martensitic phase transformation strengthening. 相似文献
39.
The kinetics of C6H5 reactions with n‐CnH2n+2 (n = 3, 4, 6, 8) have been studied by the pulsed laser photolysis/mass spectrometric method using C6H5COCH3 as the phenyl precursor at temperatures between 494 and 1051 K. The rate constants were determined by kinetic modeling of the absolute yields of C6H6 at each temperature. Another major product C6H5CH3 formed by the recombination of C6H5 and CH3 could also be quantitatively modeled using the known rate constant for the reaction. A weighted least‐squares analysis of the four sets of data gave k (C3H8) = (1.96 ± 0.15) × 1011 exp[?(1938 ± 56)/T], and k (n‐C4H10) = (2.65 ± 0.23) × 1011 exp[?(1950 ± 55)/T] k (n‐C6H14) = (4.56 ± 0.21) × 1011 exp[?(1735 ± 55)/T], and k (n?C8H18) = (4.31 ± 0.39) × 1011 exp[?(1415 ± 65)T] cm3 mol?1 s?1 for the temperature range studied. For the butane and hexane reactions, we have also applied the CRDS technique to extend our temperature range down to 297 K; the results obtained by the decay of C6H5 with CRDS agree fully with those determined by absolute product yield measurements with PLP/MS. Weighted least‐squares analyses of these two sets of data gave rise to k (n?C4H10) = (2.70 ± 0.15) × 1011 exp[?(1880 ± 127)/T] and k (n?C6H14) = (4.81 ± 0.30) × 1011 exp[?(1780 ± 133)/T] cm3 mol?1 s?1 for the temperature range 297‐‐1046 K. From the absolute rate constants for the two larger molecular reactions (C6H5 + n‐C6H14 and n‐C8H18), we derived the rate constant for H‐abstraction from a secondary C? H bond, ks?CH = (4.19 ± 0.24) × 1010 exp[?(1770 ± 48)/T] cm3 mol?1 s?1. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 36: 49–56, 2004 相似文献
40.