Powder metallurgical materials and processes for soft magnetic applications

For many designers of electrical machines, the term “soft magnetic materials” automatically means laminated electrical sheet. This is unfortunate, since for many applications, particularly at low frequencies, laminated sheet is rarely the best material choice. Soft magnetic powder materials are available to satisfy the needs of virtually any application imaginable, from plain iron, giving good induction for DC applications, to ultra-high permeability nickel irons. The use of these materials brings with it all the attendant advantages of powder metallurgical (PM) production: low cost, tight tolerances, complicated forms, and minimal material waste. For high frequency applications, a range of soft magnetic composite materials or SMCs are available which can provide magnetic performance comparable to or surpassing that of laminated sheets, while at the same time allowing much greater freedom to the designer due to their isotropic nature, which permits the implementation of complicated 3D flux paths. This paper presents a review of the available powder-based soft magnetic materials, together with typical applications and a consideration of some of the factors which must be taken into account when producing powder-based components for magnetic applications

Do the constants of nature couple to strong gravitational fields?

Recently, white dwarf stars have found a new use in the fundamental physics community. Many prospective theories of the fundamental interactions of Nature allow traditional constants, like the fine structure constant $\alpha$, to vary in some way. A study by Berengut et al. (2013) used the Fe/Ni V line measurements made by Preval et al. (2013) from the hot DA white dwarf G191-B2B, in an attempt to detect any variation in $\alpha$. It was found that the Fe V lines indicated an increasing alpha, whereas the Ni V lines indicated a decreasing alpha. Possible explanations for this could be misidentification of the lines, inaccurate atomic data, or wavelength dependent distortion in the spectrum. We examine the first two cases by using a high S/N reference spectrum from the hot sdO BD+28$^{\circ}$4211 to calibrate the Fe/Ni V atomic data. With this new data, we re-evaluate the work of Berengut et al. (2013) to derive a new constraint on the variation of alpha in a gravitational field.Comment: 4 pages, 2 figures: To appear in the proceedings of the "19th European White Dwarf Workshop" in Montreal, Canada, 201

Constraints on lateral gene transfer in promoting fimbrial usher protein diversity and function.

Fimbriae are long, adhesive structures widespread throughout members of the family Enterobacteriaceae. They are multimeric extrusions, which are moved out of the bacterial cell through an integral outer membrane protein called usher. The complex folding mechanics of the usher protein were recently revealed to be catalysed by the membrane-embedded translocation and assembly module (TAM). Here, we examine the diversity of usher proteins across a wide range of extraintestinal (ExPEC) and enteropathogenic (EPEC) Escherichia coli, and further focus on a so far undescribed chaperone-usher system, with this usher referred to as UshC. The fimbrial system containing UshC is distributed across a discrete set of EPEC types, including model strains like E2348/67, as well as ExPEC ST131, currently the most prominent multi-drug-resistant uropathogenic E. coli strain worldwide. Deletion of the TAM from a naive strain of E. coli results in a drastic time delay in folding of UshC, which can be observed for a protein from EPEC as well as for two introduced proteins from related organisms, Yersinia and Enterobacter We suggest that this models why the TAM machinery is essential for efficient folding of proteins acquired via lateral gene transfer

A Quadratic Spinor Lagrangian for General Relativity

We present a new finite action for Einstein gravity in which the Lagrangian is quadratic in the covariant derivative of a spinor field. Via a new spinor-curvature identity, it is related to the standard Einstein-Hilbert Lagrangian by a total differential term. The corresponding Hamiltonian, like the one associated with the Witten positive energy proof is fully four-covariant. It defines quasi-local energy-momentum and can be reduced to the one in our recent positive energy proof. (Fourth Prize, 1994 Gravity Research Foundation Essay.)Comment: 5 pages (Plain TeX), NCU-GR-94-QSL

A history of north east shipbuilding: being an attempt to describe and analyse the development of shipbuilding in the North East of England from earliest times to the end of 1967

At the end of the 19th century, the United Kingdom produced four out of every five ships built in the whole world, and the North East coast of England, stretching from Blyth in the North to Whitby in the South, was responsible for two out of those five ships. A government enquiry said that the United Kingdom performance was an industrial achievement almost without parallel. Clearly the contribution by the North East was a substantial one. Together with the river Clyde, the North East of England has been the major shipbuilding area in the country and until recently one of the main areas in the whole world. Yet this supremacy did not start to emerge until about half way through the 19th century when iron began to usurp wood and steam began to usurp sail. These two technical changes turned a craft into an industry and no area was as successful in adapting to the new era as the North west coast. Its natural resources of coal and iron were exploited by a group of brilliant entrepreneurs who literally fashioned the industry. They were responsible not only for organising production; they also stimulated technical innovations. The turbine engine was developed in the region; so was the oil tanker. There are many other examples. British - and North East - supremacy lasted for 100 years. By the 1950's competition from other countries and an inability to expand meant that British - and North East - shipbuilding had to yield its place as a world leader. Today Japan is almost as dominant as the United Kingdom was at the end of the 19th century. This story of the rise and fall of a great industry is not yet finished, however. In 1968 there were strong indications that the industry was going through a period of rejuvenation and reinvigoration, ready to challenge foreign competition more strongly than it had done in the 1950's and early l960's

Antibiotic Resistance and Typhoid.

Multiple drug (antibiotic) resistance (MDR) has become a major threat to the treatment of typhoid and other infectious diseases. Since the 1970s, this threat has increased in Salmonella enterica serovar Typhi, driven in part by the emergence of successful genetic clades, such as haplotype H58, associated with the MDR phenotype. H58 S. Typhi can express multiple antibiotic resistance determinants while retaining the ability to efficiently transmit and persist within the human population. The recent identification of extensively drug resistant S. Typhi only highlights the dangers of ignoring this threat. Here we discuss the evolution of the S. Typhi MDR phenotype and consider options for management