Magnetic scattering effects in two-band superconductor: the ferromagnetic dopants in MgB2.

This paper demonstrates the magnetic scattering effects on the electron-phonon interaction in two-band superconductors based on the transition-metal-doped MgB2 to clarify the effects of magnetic dopants on multi-band superconductivity. The phonon properties of polycrystalline Mg(1-x)M(x)B2 (M = Fe, Ni and Co), with x up to 0.05, were studied, with the investigation based on the normal state Raman spectra, especially the variation of the E(2g) mode. The magnetic scattering effect of Fe is much weaker than that of Mn in MgB2, while it is stronger than that of Ni. The weak magnetic scattering effects are responsible for the superconducting behaviors of Mg(1 - x)Fe(x)B2 and Mg(1 - x)Ni(x)B2. Co shows almost no magnetic scattering effects on the superconductivity, while the depression of the critical temperature, T(c), in Mg(1 - x)Co(x)B2 is attributed to the phonon behavior and is independent of the ferromagnetic nature of cobalt.

Decoupling of normal CD40/interleukin-4 immunoglobulin heavy chain switch signal leads to genomic instability in SGH-MM5 and RPMI 8226 multiple myeloma cell lines.

The processes mediating genomic instability and clonal evolution are obscure in multiple myeloma (MM). Acquisition of new chromosomal translocations into the switch region of the immunoglobulin heavy chain (IgH) gene (chromosome 14q32) in MM, often heralds transformation to more aggressive disease. Since the combined effects of CD40 plus interleukin-4 (IL-4) mediate IgH isotype class switch recombination (CSR), and this process involves DNA double strand break repair (DSBR), we hypothesized that CD40 and/or IL-4 activation of MM cells could induce abnormal DNA DSBR and lead to genomic instability and clonal evolution. In this study, we show that MM cell lines that are optimally triggered via CD40 and/or IL-4 demonstrate abnormal decoupling of IL-4 signal transduction from CD40. Specifically, CD40 alone was sufficient to trigger maximal growth of tumor cells. We further demonstrate that CD40 triggering induced both DNA DSBs as well as newly acquired karyotypic abnormalities in MM cell lines. Importantly, these observations were accompanied by induction of activation induced cytidine deaminase expression, but not gross apoptosis. These data support the role of abnormal CD40 signal transduction in mediating genomic instability, suggesting a role for the CD40 pathway and intermediates in myelomagenesis and clonal evolution in vivo.

A modified equivalent annulus model for the hollow fiber hemodialyzer.

Experimental approaches to optimize hollow fiber hemodialyzer design are expensive and time-consuming. Computer modeling is an effective way to study mass transfer in the hemodialyzer because a substantial reduction in experimental time and cost can be achieved. This paper presents a two-dimensional modified "equivalent annulus" model, which employs Navier-Stokes (N-S) equations to describe blood and dialysate flow, and Kedem-Katchalsky (K-K) equations to calculate transmembrane flow. N-S equations and K-K equations must be coupled together in the process of computing. The corresponding experiments were designed to validate this model, and experimental results agreed well with numerical results. The distribution of velocity, pressure and solute concentration were investigated in detail, presenting a clear insight into dialyzer mass transfer. This model can be applied to help optimize hemodialyzer design.