Magnetic properties of 36 wt% Ni-Fe alloys

This paper reports the effect of adding molybdenum, chromium or copper, in amounts up to 5 wt%, on the initial permeability μ_i, magnetostriction constant λ_ps and saturation magnetisation M_s of a 36 wt% Ni-Fe alloy. Mo and Cr decrease λ_ps and M_s, but Cu has the opposite effect. The initial permeability is increased by Mo and Cr additions, except at high concentrations, whereas Cu produces little change in μ_i. Changes in the magnetic moment per atom are discussed in terms of the effect of alloying on the mean number of (d+s) outer electrons. It is suggested that the change in magnetic moment per atom may influence the value of μ_i indirectly due to changes in the spin-orbit and exchange interactions, which alter the anisotropy and magnetostriction constants and domain wall energy.     

The compression modulus of the nucleon and delta

The compressibility of the nucleon and delta are calculated in a variety of models, and its relevance to the compression of nuclear matter is discussed. The limiting temperature of a constituent phase is also examined.     

Femtosecond laser-based fabrication of a new model material to study fracture

The ductile fracture process consists of the nucleation, growth and coalescence of voids in a material. Predictive models of ductility require a complete understanding of the coalescence event. However, coalescence occurs over very small strains and is therefore difficult to observe experimentally. We have addressed this by developing a new class of model material. It consists of femtosecond laser drilled holes and diffusion bonded metallic sheets, which can be mechanically tested in situ either by scanning electron microscopy (SEM) or by X-raycomputed tomography (XRCT). The fabrication steps are presented and the model material is characterized by optical and electron microscopy, nanoindentation and tomography. The heat affected zone around the laser holes is found to be harder than the unaffected material and consists of nano-scale grains. Finally we show that the coalescence event is well captured using both SEM and XRCT. The fabrication method is adaptable to a wide range of materials and enables one to produce 2D and 3D arrays of holes or cracks with controlled size, volume fraction and distribution. PACS  62.20.Mk; 62.25.+g; 79.20.Ds     

The influence of sterics on the formation of polar 1-D hydrogen-bonded networks

Polar, noncentrosymmetric packing of directional, 1-D hydrogen-bonded networks of chiral, 4-amino-2,6-bis(oxazolinyl)pyridines (ampybox) occurs for isopropyl-substituted ampybox; in contrast, 1-D networks of methyl-substituted ampybox pack in an antiparallel arrangement.     

The mass spectra of sydnones

The mass spectra of thirty sydnoes have been interpreted; the types investigated include 3-aryl, 3-alkyl-, substituted 3-alkylsydnones; and bis sydnones. A characteristic fragmentation mode involves initial loss of NO and CO from the molecular ion, but peaks corresponding to alkylcarbonium ions dominate the spectra of 3-alkylsydnones; a cyclic mechanism is suggested for weak transitions involving loss of sydnone neutral molecule from the molecular ion. A mechanism is proposed for loss of chlorine radical from the molecular ion of 3-(2,4-dichlorophenethyl)sydnone. An unusual feature in the mass spectrum of trimethylenebis sydnone is rationalised on the basis of a precursor 1,2,3-oxadiazole ion. The effect of substituents in the aryl ring on the fragmentation of 3-arylsydnones is discussed.     

The mass spectra of 1,2,4-triazines and related compounds

The mass spectra of monocyclic 1,2,4-triazines and 1,2,4-triazines fused to a pyrazole ring through a bridgehead nitrogen have been investigated: fragmentation pathways were elucidated by the use of metastable ions and high resolution mass measurements. The spectra of the monocyclic 1,2,4-triazines indicate that loss of nitrogen from the molecular ions is a relatively unimportant feature. The decomposition modes of the bicyclic pyrazolo[3,2-c]-as-triazines are sensitive to the nature of the substituent in the triazine ring.