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61.
62.
The non-stationary response in vibrating systems with power-law damping, subjected to sweep tests is considered. Using the method of averaging, it is shown that the bifurcation delay persists in all forms of power-law damping, viz., Coulomb, orifice and cubic damping models. Experimental investigations on a soft type of isolator confirm the existence of delay in the jump phenomenon. These results also indicate that the softening nature of non-linearity can be profitably employed in the design of isolators and vehicle suspensions. 相似文献
63.
This paper describes the design, synthesis, and evaluation of transition metal complexes capable of recognizing flexible histidine-containing peptides in aqueous medium (25 mM HEPES buffer, pH = 7.0, 25 degrees C). When the pattern of metal ions on a complex matches with the pattern of histidine moieties on the peptide, strong interaction (K = 1.2 x 10(6) M-1) can be achieved. The complex was highly selective (> 200:1) in discriminating similar flexible peptides differing only by one glycine unit. 相似文献
64.
Atsuomi Shundo Abul K. Mallik Toshihiko Sakurai Makoto Takafuji Shoji Nagaoka Hirotaka Ihara 《Journal of chromatography. A》2009,1216(34):6170-6176
Poly(l-alanine)-grafted porous silica (Sil-Ala22) was prepared by polymerization of N-carboxyanhydride of l-alanine initiated by 3-aminopropylated silica. The retention behaviors of the column packed with Sil-Ala22 were investigated by using alkylbenzenes and polycyclic aromatic hydrocarbons as injection samples in liquid chromatography. The Ala22 phase was in a rigid β-form structure and thus provided specific interaction sites, which were derived from the highly ordered carbonyl and methyl groups. These interaction sites bring unique molecular-shape discriminations: molecular-length and non-planarity selectivity, which are controllable by altering organic solvent used as a part of mobile phase. 相似文献
65.
The copolymer with a terminal reactive group (copoly-VP17MA12) was newly designed and prepared by selecting 4-vinylpyridine (VP) as an electron-donating monomer and methyl acrylate (MA) as an electron-accepting monomer. Copoly-VP17MA12 was grafted onto porous silica particles by a silanol coupling reaction with the terminal group. Individually, poly-VP15 and poly-MA20 with a terminal reactive group were also synthesized and co-grafted onto silica (Sil-cograft-VP15MA20) to compare the effect of the copolymer-grafted (Sil-copoly-VP17MA12) and polymer co-grafted stationary phases in HPLC separation. All the polymers were characterized by 1H NMR and FT-IR analysis before grafting on silica. Polymer grafting was confirmed by diffuse reflectance infrared Fourier transform (DRIFT), elemental analysis and thermogravimetric analysis (TGA). The intra- and intermolecular interaction between monomer units in copolymer-grafted and polymer co-grafted systems, respectively was observed by DRIFT measurement. The detailed chromatographic study revealed using PAHs as solutes that remarkably higher selectivity for planar/non-planar discrimination was observed with the copolymer-grafted phase than with the co-grafted stationary phase. In this paper, it is also discussed that the selectivity enhancement by copolymer-grafting in the Sil-copoly-VP17MA12 phase can be brought through intramolecular interaction between VP and MA. 相似文献
66.
The design of o-nitrobenzyl containing photocleavable lipid-amino acid conjugates, and their application in liposomal uncorking are described. 相似文献
67.
Usually, lipids are synthesized employing solution-phase organic synthesis techniques. Though successful, the purifications can be difficult to accomplish due to the amphiphilic nature of the molecules. Herein, we demonstrate the advantages of a solid-phase approach for preparing a variety of metal-chelating lipids. A number of saturated and polymerizable metal-chelating lipids were prepared using this methodology. This approach requires one chromatographic purification after cleaving the lipids from the solid support. We also demonstrate that the resulting polymerized liposomes (containing Eu3+) possess the appropriate luminescence properties for the qualitative and quantitative determination of proteins. 相似文献
68.
Free vibration characteristics of a thin walled, open cross-section beam, with constrained damping layers at the flanges, are investigated. Both uncoupled transverse vibration and the coupled bending-torsion oscillations, of a beam of a top-hat section, are considered. Numerical results are presented for natural frequencies and modal loss factors in the first two modes of simply supported and clamped-clamped beams. For the uncoupled mode the constrained damping treatment is more effective than an unconstrained one, but for the coupled mode the effect is just the opposite. 相似文献
69.
We consider the thermal correlation functions of vector and axial-vector currents and evaluate corrections to the vector
and axial-vector meson pole terms to one loop in chiral perturbation theory. As expected, the pole positions do not shift
to leading order in temperature. But the residues decrease with temperature. We review briefly other methods in the literature
to determine these pole parameters. We find our evaluation to disprove a result on the mixing of the correlation functions
at finite temperature.
Received: 30 May 2002 / Published online: 30 August 2002 相似文献
70.
We try to determine light quark masses by considering sum rules for the vacuum expectation value of the time-ordered correlation function of two divergences of the axial vector current. The evaluation is carried out at momenta high enough for the non-perturbative contributions to be negligible. We find that the average mass of the up and down quark at a momentum of 1 GeV lies between 3.3 and 7.9 MeV while that for the strange quark lies between 84 and 212 MeV. The ranges of values reflect predominantly the uncertainty in the absorptive part in the low energy region (?1.7 GeV). 相似文献