The change of the saturation magnetization of Fe films with the pressure of nitrogen during deposition ranging from 2 × 10−5 to 7 × 10−3 Torr has been investigated systematically. We found a new magnetic material which has the highest saturation magnetization at room temperature, 2050 G, among those of all the magnetic materials. This was attributed to Fe16N2, which has a bct structure, and the magnetic moment associated with Fe atoms of Fe16N2 was deduced to be 3.0 μB.

Synthesis and magnetic properties of gold coated iron oxide nanoparticles J. Appl. Phys. 105, 07B504 (2009); 10.1063/1.3059607 Synthesis of self-assembled monodisperse 3 nm FePd nanoparticles: Phase transition, magnetic study, and surface effectThe monodisperse Fe 3 O 4 nanocubes with controllable sizes from 6.5 to 30.0 nm have been synthesized in one pot. The shape-induced texture of the self-assembled nanocube superlattices has been deposited onto substrates by a convective assembly technique. The cubelike shapes affect the crystalline orientation of individual particles within the self-assembled superlattices compared with the nanoparticles with an isotropic spherical shape. The nanocubes with a size less than 25 nm show a typical superparamagnetic behavior at room temperature. Comparison of the hysteresis loop at 5 K of cubes with different sizes reveals a size-dependent behavior of saturation magnetization and coercivity.

We measured dynamic shear moduli of poly(macromonomer)s of an increased backbone chain length and those bearing branch chains of increased branch length up to the critical molecular weight for the intermolecular chain entanglement, M c, of a linear polystyrene as functions of frequency and temperature using a parallel-plate rheometer. The poly(macromonomer)s were prepared from ω-methacryloyloxyethyl polystyrene macromonomers (MA-PSt)s or ω-vinylbenzyl polystyrene macromonomers (VB-PSt)s. It was revealed that a great increase in the backbone length caused the poly-(macromonomer)s to show a weak rubbery plateau region in the master curves of the storage modulus G′, where the molecular weights of the branch chains were smaller than Mc. The plateau modulus was much lower than that observed for the linear polystyrenes. On the other hand, the poly(macromonomer)s with polystyrene branches are nearly equal to the Mc, and a very short backbone chain showed a clear rubbery plateau region. The glass transition temperature of poly(macromonomer)s in the region without the chain entanglement decreased with decreasing branch length but remained almost constant over the wide range of the backbone length.

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Sheep susceptibility to scrapie is governed by polymorphisms at two major sites, codons 136 and 171, of the prp gene. To get more insight into the prion protein (PrP) sequence-linked basis of differential scrapie susceptibility, a high yield one-step method for the purification (over 99% final purity) of the full-length recombinant sheep PrP was developed, based on the affinity of the conserved octapeptide repeats for transition-metal cations. Thermal and chemical denaturation experiments and limited proteolysis studies were performed on the natural variants (A136R171, V136Q171 and A136Q171) and a recombinant PrP mutated at position 136 (V136R171). Results revealed the influence of mutations in positions 136 and 171 on the folding thermodynamic parameters and on the conformation of the C-terminal domain. Together, our results show that the VQ cellular protein linked to higher scrapie susceptibility is intrinsically more compact and/or stable than the resistance-linked AR counterpart. This might lead to a lower in vivo clearance rate of VQ and a consequently higher probability of occurrence of pathological events.Keywords: sheep prion protein; sheep PrP variants; scrapie; PrP stability.Prion diseases are fatal neurodegenerative disorders affecting several mammalian species which can be of sporadic, inherited or transmissible origin [1]. Wide body of data, obtained from experimentally infected model species, supports the hypothesis that a conformational change in the host cellular prion protein is the key molecular event associated with this illness [2]. The pathological`scrapie' PrP conformation (PrP sc ) is characterized by increased b-sheet content, higher tendency to self-association, insolubility and protease resistance [3].In recent years, the availability of recombinant full-length mouse (mPrP) [4], Syrian hamster PrP [5], bovine [6] and human (human PrP) [7] PrPs, as well as their C-terminal domains, namely mouse PrP(121±231) [8], human PrP(90±231) [9,10] and Syrian hamster PrP(90±231) [11], rendered prion protein amenable to NMR structural analysis. In two species studied so far, mouse and Syrian hamster [5,12], PrPs show similar features, namely a rather unstructured N-terminal domain (23±120/23±124) linked to a structured core domain encompassing residues 121±231 (125±228 in SHaPrP). The latter consists in both cases in three a helices and two short antiparallel b strands [13,14].In mammals, several natural polymorphisms within the open reading frame of the prp gene influence the susceptibility of the host to prion diseases [15]. The corresponding amino-acid substitutions could affect the intrinsic stability of the protein, its folding pathways or ligand binding properties, or yet its clearance kinetics. All these factors could have significant influence on the progress of pathological processes. In sheep, a well defined polymorphism governs susceptibility to scrapie. Animals homozygous for the allele encoding the V136R154Q171 (VQ) variant exhibit high susceptibility to scrapie while those homozygous fo...