Lamellar magnets

The structures of electroplated hard alloys have been less extensively studied than those of similar electrolessly deposited materials. Sallo and co-workers [118-120] have investigated the relationship between the structure and the magnetic properties of CoP and CoNiP electrodeposits. The structures and domain patterns were different for deposits with different ranges of coercivity. The lower-f/c materials formed lamellar structures with the easy axis of magnetization in the plane of the film. The high-Hc deposits, on the other hand, had a rod-like structure, and shape anisotropy may have contributed to the high coercivity. The platelets and rods are presumed to be isolated by a thin layer of a nonmagnetic material. 

Fig. 5 Membrane models for NMR structure analysis, (a) An isotropic detergent micelle (left) is compared to the dimensions of lipid bilayers (right), (b) Macroscopically oriented membrane samples can be prepared on solid support, as nanodiscs, or as magnetically oriented bicelles. (c) Nomenclature and variability of liposomes small (SUV, 20-40 nm), intermediate (IUV, 40-60 nm), large (LUV, 100-400 nm), and giant unilamellar vesicles (GUV, 1 pm) multi-lamellar (MLV), oligo-lamellar (OLV) and highly heterogeneous multi-oligo-lamellar vesicles (MOLV)...

In this final section, it is shown that the three magnetic field components of electromagnetic radiation in 0(3) electrodynamics are Beltrami vector fields, illustrating the fact that conventional Maxwell-Heaviside electrodynamics are incomplete. Therefore Beltrami electrodynamics can be regarded as foundational, structuring the vacuum fields of nature, and extending the point of view of Heaviside, who reduced the original Maxwell equations to their presently accepted textbook form. In this section, transverse plane waves are shown to be solenoidal, complex lamellar, and Beltrami, and to obey the Beltrami equation, of which B is an identically nonzero solution. In the Beltrami electrodynamics, therefore, the existence of the transverse 1 = implies that of , as in 0(3) electrodynamics. 

Beltrami fields have been advanced [4] as theoretical models for astrophy-sical phenomena such as solar flares and spiral galaxies, plasma vortex filaments arising from plasma focus experiments, and superconductivity. Beltrami electrodynamic fields probably have major potential significance to theoretical and empirical science. In plasma vortex filaments, for example, energy anomalies arise that cannot be described with the Maxwell-Heaviside equations. The three magnetic components of 0(3) electrodynamics are Beltrami fields as well as being complex lamellar and solenoidal fields. The component is identically nonzero in Beltrami electrodynamics if is so. In the Beltrami... 

Figure 8-10 2H NMR spectra of dimyristoyl phosphatidyl-cholme-d27/water in lamellar phases at 40°C. One chain of the phosphatidylcholine is fully deuterated, containing 27 atoms of 2H. The mole ratios of water to lipid were 5.0 in (A) and 25.0 in (B). The average interfacial areas per alkyl chain as measured hy X-ray diffraction were 0.252 nm2 for (A) and 0.313 nm2 for (B). 2H NMR spectra are presented as "powder patterns" because the lipid molecules are randomly oriented in the magnetic field of the spectrometer as if in a powder. This gives rise to pairs of peaks symmetrically located on both sides of the origin. The separation distances are a measure of the quadrupole splitting of the NMR absorption line caused by the 2H nucleus. The various splittings of the resonances of the 13 -CH2- and one -CH3 groups reflect differences in mobility.109 The peaks have been assigned tentatively as indicated. From Boden, Jones, and Sixl.115 Courtesy of N. Boden.

Figure 21 Effect of macroscopic orientation on 3,P NMR spectra of PL membranes. (A) Multi-lamellar PL vesicles yield 31P NMR spectra that are characterised by an axially symmetric shielding tensor. If lamellar lipid membranes are oriented between glass plates, a single 3,P NMR signal is obtained for any given orientational angle between the membrane normal and the external magnetic field B0. 31P NMR spectra for (B) perpendicular and (C) parallel orientations are shown. Taken from Ref. [86].

Bujoli B., Pena O., Palvadeau R, Le Bideau J., Payen, C. and Rouxel J., Synthesis, structure and magnetic properties of a new lamellar iron phosphonate, Fe"(C2H5P03) H20, Chem. Mater. 5 (1993) pp. 583. 

Figure 18.7 3,P NMR spectra of MSI-103 in DMPC. (a) P/L= 1 200, nonoriented multilamellar vesicles sample. The broad signal shows the typical powder spectrum of a liquid crystalline lamellar lipid phase, (b) P/L = 1 20, macroscopically oriented sample. The peak around 28 ppm shows that the sample is well oriented with the lipid bilayer normal oriented parallel to the magnetic field.

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