The effect of the addition of fly ash on the hydration of cement

Imperial Users onl

ac Losses in a Finite Z Stack Using an Anisotropic Homogeneous-Medium Approximation

A finite stack of thin superconducting tapes, all carrying a fixed current I, can be approximated by an anisotropic superconducting bar with critical current density Jc=Ic/2aD, where Ic is the critical current of each tape, 2a is the tape width, and D is the tape-to-tape periodicity. The current density J must obey the constraint \int J dx = I/D, where the tapes lie parallel to the x axis and are stacked along the z axis. We suppose that Jc is independent of field (Bean approximation) and look for a solution to the critical state for arbitrary height 2b of the stack. For c<|x|<a we have J=Jc, and for |x|<c the critical state requires that Bz=0. We show that this implies \partial J/\partial x=0 in the central region. Setting c as a constant (independent of z) results in field profiles remarkably close to the desired one (Bz=0 for |x|<c) as long as the aspect ratio b/a is not too small. We evaluate various criteria for choosing c, and we show that the calculated hysteretic losses depend only weakly on how c is chosen. We argue that for small D/a the anisotropic homogeneous-medium approximation gives a reasonably accurate estimate of the ac losses in a finite Z stack. The results for a Z stack can be used to calculate the transport losses in a pancake coil wound with superconducting tape.Comment: 21 pages, 17 figures, accepted by Supercond. Sci. Techno

Fermi Surface Properties of Low Concentration Cex_{x}La1−x_{1-x}B6_{6}: dHvA

The de Haas-van Alphen effect is used to study angular dependent extremal areas of the Fermi Surfaces (FS) and effective masses of Ce$_{x}$La$_{1-x}$B$_{6}$ alloys for $x$ between 0 and 0.05. The FS of these alloys was previously observed to be spin polarized at low Ce concentration ($x$ = 0.05). This work gives the details of the initial development of the topology and spin polarization of the FS from that of unpolarized metallic LaB$_{6}$ to that of spin polarized heavy Fermion CeB$_{6}$ .Comment: 7 pages, 9 figures, submitted to PR

Theory of interlayer exchange interactions in magnetic multilayers

This paper presents a review of the phenomenon of interlayer exchange coupling in magnetic multilayers. The emphasis is put on a pedagogical presentation of the mechanism of the phenomenon, which has been successfully explained in terms of a spin-dependent quantum confinement effect. The theoretical predictions are discussed in connection with corresponding experimental investigations.Comment: 18 pages, 4 PS figures, LaTeX with IOP package; v2: ref. added. Further (p)reprints available from http://www.mpi-halle.de/~theory

O(12) limit and complete classification of symmetry schemes in proton-neutron interacting boson model

It is shown that the proton-neutron interacting boson model (pnIBM) admits new symmetry limits with O(12) algebra which break F-spin but preserves the quantum number M_F. The generators of O(12) are derived and the quantum number `v' of O(12) for a given boson number N is determined by identifying the corresponding quasi-spin algebra. The O(12) algebra generates two symmetry schemes and for both of them, complete classification of the basis states and typical spectra are given. With the O(12) algebra identified, complete classification of pnIBM symmetry limits with good M_F is established.Comment: 22 pages, 1 figur

Effect of Lactobacillus casei on the production of pro-inflammatory markers in streptozotocin-induced diabetic rats.

It has been demonstrated that probiotic supplementation has positive effects in several murine models of disease through influences on host immune responses. This study examined the effect of Lactobacillus casei strain Shirota (L. casei Shirota) on the blood glucose, C-reactive protein (CRP), Interleukin-6 (IL-6), Interleukin-4 (IL-4), and body weight among STZ-induced diabetic rats. Diabetes mellitus was induced by streptozotocin (STZ, 50 mg/kg BW) in male Sprague–Dawley rats. Streptozotocin caused a significant increase in the blood glucose levels, CRP, and IL-6. L. casei Shirota supplementation lowered the CRP and IL-6 levels but had no significant effect on the blood glucose levels, body weight, or IL-4. Inflammation was determined histologically. The presence of the innate immune cells was not detectable in the liver of L. casei Shirota-treated hyperglycemic rats. The probiotic L. casei Shirota significantly lowered blood levels of pro-inflammatory cytokines (IL-6, CRP) and neutrophils in diabetic rats, showing a lower risk of diabetes mellitus and its complications