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21.
We investigate the electronic properties of multiwalled carbon nanotubes both before and after acid treatment with concentrated sulphuric and nitric acids. Magnetic susceptibility measurements were performed using a SQUID magnetometer and show that there is a considerable enhancement in the density of states at the Fermi level. The data shows that the diamagnetic influence from the graphitic nanotubes dominates. We experimentally observe, after acid treatment, that the diamagnetic susceptibility remains unchanged at 5 K but notably decreases at 77 K. We propose the acid treatment has increased the Van Vleck paramagnetic contribution lowering the diamagnetic response from the π-electron orbital magnetisation. The Van Vleck paramagnetic contribution is finite-temperature dependent with a diminishing contribution at higher fields. 相似文献
22.
We study the chiral behavior of the nucleon and Δ-isobar masses within a manifestly covariant chiral effective-field theory, consistent with the analyticity principle. We compute the πN and πΔ one-loop contributions to the mass and field-normalization constant, and find that they can be described in terms of universal relativistic loop functions, multiplied by appropriate spin, isospin and coupling constants. We show that these manifestly relativistic one-loop corrections, when properly renormalized, obey the chiral power-counting and vanish in the chiral limit. The results including only the πN-loop corrections compare favorably with the lattice QCD data for the pion-mass dependence of the nucleon and Δ masses, while inclusion of the πΔ loops tends to spoil this agreement. 相似文献
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E. V. Voronina E. P. Yelsukov A. V. Korolyov A. E. Yelsukova 《Hyperfine Interactions》2006,168(1-3):1079-1083
The experimental data from Mössbauer spectroscopy and magnetic measurements are presented as functions of the temperature and external magnetic field for a B2-type ordered Fe 66 Al 34 alloy. 相似文献
25.
We study the phase diagram of the strongly interacting matter at finite temperatures and densities including 2SC, uniform chiral and non-uniform chiral phases within the Nambu–Jona-Lasinio model in the mean field approximation. 相似文献
26.
系列类立方烷型Fe4S4簇合物的XPS分析 总被引:1,自引:0,他引:1
对7种类立方烷型Fe_4S_4簇合物进行了XPS分析,得到了中心离子Fe的价态,给出了系列Fe_4S_4中骨架硫的结合能,由峰合成结果给出各种S、N的比例与按结构式计算的结果相同。 相似文献
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29.
Fe(phen)32+与DNA作用的荧光光度法研究 总被引:1,自引:1,他引:0
为了考察金属配合物Fe(phen)32+与DNA 的作用模式, 应用荧光光度法对Fe(phen)32+与DNA及DNA-EB的作用进行了研究,结果表明Fe(phen)32+是主要以共轭平面插入形式与DNA作用的, 并计算出稳定常数等一系列热力学数据. 相似文献
30.
M. López Granados F. Cabello Galisteo M. Alifanti J.L.G. Fierro 《Applied Surface Science》2006,252(24):8442-8450
This work reports the research carried out by studying aliquots extracted at different axial coordinates from Three Way Catalyst (TWC) monoliths aged under real traffic conditions. Our study focused on the catalytic properties and on several chemical and physical effects caused in the Front and Rear monolith washcoat surfaces by vehicle aging after 60,000 km. Regarding the catalytic properties, all the used aliquots showed poorer activity than their corresponding fresh counterparts. The strongest deactivation was detected for NO and hydrocarbon conversion. CO conversion was less affected and the Rear monolith was as deactivated as the Front one. The characterisation techniques (TXRF, N2 adsorption-desorption isotherms, XRD and H2-TPR) detected - (i) the deposition of P, Zn and Pb; (ii) the formation of CePO4 on account of the Ce from the washcoat; (iii) thermal sintering; (iv) inhibition of the reducibility of Ce oxides - as the main effects brought about by vehicle aging conditions. The deactivation observed at the beginning of the Front monolith was the result of a combination of the former effects. When moving downstream to higher axial coordinates, Pb accumulation and the loss of specific area appeared to be the only probable sources of deactivation. 相似文献