The response of a floating ice sheet to an accelerating line load

The two-dimensional response of a thin, floating sheet of ice to a line load that accelerates from rest at $t = 0$ to a uniform velocity V for $t \geq T$ is determined through an integral-transform solution of the linearized equations of motion. If $T = 0$ – i.e. if the load is impulsively started with velocity V – the solution exhibits singularities at $V = c_0$, the shallow-water-gravity-wave speed, and $V = c_{\min}$, the minimum speed for transverse motion of the ice, but these singularities are avoided by the acceleration of the load through the critical speeds

Investigation of the phase behaviour of the 1: 1 adduct of mesitylene and hexafluorobenzene

Variable temperature X-ray diffraction has been used to probe the structure and dynamics of the solid adducts of 1,3,5-trimethylbenzene (mesitylene) and hexafluorobenzene. PXRD patterns and DSC traces of near equimolar mixtures reveal two solid-state phase-transitions at 179.2 K and 111.0 K. The crystal structures of all three solid phases of this material have been solved by SXD. In contrast to previous studies on the adduct benzene–hexafluorobenzene, there is pairing of the mesitylene and hexafluorobenzene molecules in all three phases, each consisting of close-packed parallel columns of alternating C6H3(CH3)3 and C6F6 molecules packed face to face in a staggered conformation. Differences in structure between the phases illustrate the subtle interplay of quadrupole versus bond-dipole electrostatic interactions

Observation of thermally-induced magnetic relaxation in a magnetite grain using off-axis electron holography

A synthetic basalt comprising magnetic Fe3O4 grains (~ 50 nm to ~ 500 nm in diameter) is investigated using a range of complementary nano-characterisation techniques. Off-axis electron holography combined with in situ heating allowed for the visualisation of the thermally-induced magnetic relaxation of an Fe3O4 grain (~ 300 nm) from an irregular domain state into a vortex state at 550˚C, just below its Curie temperature, with the magnetic intensity of the vortex increasing on cooling

Electronic structure and magnetic properties of RMnX (R= Mg, Ca, Sr, Ba, Y; X= Si, Ge) studied by KKR method

Electronic structure calculations, using the charge and spin self-consistent Korringa- Kohn-Rostoker (KKR) method, have been performed for several $R$Mn$X$ compounds ($R$ = Mg, Ca, Sr, Ba, Y; $X$ = Si, Ge) of the CeFeSi-type structure. The origin of their magnetic properties has been investigated emphasizing the role of the Mn sublattice. The significant influence of the Mn-Mn and Mn-$X$ interatomic distances on the Mn magnetic moment value is delineated from our computations, supporting many neutron diffraction data. We show that the marked change of $\mu_{Mn}$ with the Mn-Mn and Mn-$X$ distances resulted from a redistribution between spin-up and spin-down $d$-Mn DOS rather than from different fillings of the Mn 3$d$-shell. Bearing in mind that the neutron diffraction data reported for the $R$Mn$X$ compounds are rather scattered, the KKR computations of $\mu_{Mn}$ are in fair agreement with the experimental values. Comparing density of states near $E_{F}$ obtained in different magnetic orderings, one can notice that the entitled $R$Mn$X$ systems seem to 'adapt' their magnetic structures to minimize the DOS in the vicinity of the Fermi level. Noteworthy, the SrMnGe antiferromagnet exhibits a pseudo-gap behaviour at $E_{F}$, suggesting anomalous electron transport properties. In addition, the F-AF transition occurring in the disordered La$_{1-x}$Y$_{x}$MnSi alloy for the $0.8<x<1$ range is well supported by the DOS features of La$_{0.2}$Y$_{0.8}$MnSi. In contrast to the investigated $R$Mn$X$ compounds, YFeSi was found to be non-magnetic, which is in excellent agreement with the experimental data.Comment: 10 pages + 14 figures, to appear in Eur. Phys. Jour.