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31.
Tomoki Fukai Noriyuki Oshimo Yoshiki Kizukuri 《Zeitschrift fur Physik C Particles and Fields》1984,25(1):75-80
We present a supersymmetricSU(5)×U(1) model. This model has the following features. The gauge hierarchy is naturally generated by the quadratically divergent nature of the Fayet-IliopoulosD term. TheSU(5)×U(1) gauge symmetry breaks uniquely intoSU(3) W ×SU(2) c ×U(1) y at an energy scale of 1017–18GeV. The non-vanishing vacuum expectation value of an auxiliary field component ofU(1) gauge vector multiplet induces the breaking ofSU(2) W ×U(1) y . It gives a mass of 102–3GeV to scalar quarks and scalar leptons at the tree level. The renormalization group analysis shows that the color fine structure constant α C (M W ) becomes somewhat small and the Weinberg angle sin2θ W (M W ) somewhat too large in a simple version of the model. 相似文献
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Ryoko Fukai Piwai H. R. Dakwa Wei Chen 《Journal of polymer science. Part A, Polymer chemistry》2004,42(21):5389-5400
Epoxide and aldehyde end‐functionalized poly(ethylene glycol)s (PEGs) (Mw = 400, 1000, 3400, 5000, and 20,000) were grafted to poly(ethylene terephthalate) (PET) film substrates that contained amine or alcohol groups. PET‐PAH and PET‐PEI were prepared by reacting poly(allylamine) (PAH) and polyethylenimine (PEI) with PET substrates, respectively; PET‐PVOH was prepared by the adsorption of poly(vinyl alcohol) (PVOH) to PET substrates. Grafting was characterized and quantified by the increase of the intensity of the PEG carbon peak in the X‐ray photoelectron spectra. Grafting yield was optimized by controlling reaction parameters and was found to be substrate‐independent in general. Graft density consistently decreased as PEG chain length was increased. This is likely due to the higher steric requirement of higher molecular weight PEG molecules. Water contact angles of surfaces containing long PEG chains (3400, 5000, and 20,000) are much lower than those containing shorter PEG chains (400 and 1000). This indicates that longer PEG chains are more effective in rendering surfaces hydrophilic. Protein adsorption experiments were carried out on PET‐ and PEG‐modified derivatives using collagen, lysozyme, and albumin. After PEG grafting, the amount of protein adsorbed was reduced in all cases. Trends in surface requirements for protein resistance are: surfaces with longer PEG chains and higher chain density, especially the former, are more protein resistant; PEG grafted to surfaces containing branched or network polymers is not effective at covering the underlying substrate, and thus does not protect the entire surface from protein adsorption; and substrates containing surface charge are less protein‐resistant. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5389–5400, 2004 相似文献
34.
A method is presented for the determination of americium and curium isotopes in environmental samples, an ion-exchange clean-up procedure being used. 相似文献
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Internal friction techniques at 35 kHz were used to study the interactions between point defects and dislocations in crystals of silver chloride. The Granato-Lücke plots of the amplitude-dependent decrement were not linear, but were concave upward. Various analyses of these data all gave pin-dislocation binding energies of approximately 0·2 eV. An extensive study was made of the decay of the amplitude-independent decrement after “excitation” by high-amplitude oscillation; the Granato-Lücke L4 law was found valid, but the arrival of pins proceeded as t1/3, rather than the usual t2/3 found in deformed specimens. A first-order model of the response of a slightly perturbed Maxwell atmosphere about the dislocation is presented. The model quantitatively describes the experimental results. The activation energy of the rate constant was found to be 0·42 eV, consistent with data on solute diffusion and strain-aging. 相似文献
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Spin dependent quantum well resonance has been investigated in fully epitaxial magnetic tunnel junctions with Fe(001)/MgO(001)/ultrathin Fe(001)/Cr(001) structure. The dI/dV spectra clearly show the resonant peaks which shift systematically depending on the thickness of an ultrathin electrode as predicted in ab initio calculation [Zhong-Yi Lu et al, Phys. Rev. Lett. 94, 207210 (2005)]. The magnetotransport is strongly modulated at the same bias voltage as the resonant peaks. This control of the magnetotransport in magnetic tunnel junctions at a specific bias voltage will contribute to the development of active spintronic devices. 相似文献
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A method is proposed for measuring simultaneously several actinide elements by alpha-spectrometry. The actinides in sample solutions are sorbed together on an anion-exchange column from a nitric acid-methanol mixture. After simultaneous elution and electroplating on a disc, the actinides are determined by alpha-spectrometry. Radiochemical yields of the procedure for Th, U, Np, Pu, Am and Cm are better than 50%, all falling within a range of +/- 5%. Examples of the application of this method to various marine environmental samples such as sea-water, seaweed and marine sediment are presented. 相似文献