c(2x2) Interface Alloys in Co/Cu Multilayers - Influence on Interlayer Exchange Coupling and GMR

The influence of a c(2x2) ordered interface alloy of 3d transition metals at the ferromagnet/nonmagnet interface on interlayer exchange coupling (IXC), the formation of quantum well states (QWS) and the phenomenon of Giant MagnetoResistance is investigated. We obtained a strong dependence of IXC on interface alloy formation. The GMR ratio is also strongly influenced. We found that Fe, Ni and Cu alloys at the interface enhance the GMR ratio for in-plane geometry by nearly a factor of 2.Comment: 14 pages, 5 figures, 1 table, subm. to PR

Reformulation of the LDA+U method for a local orbital basis

We present a new approach to the evaluation of the on-site repulsion energy U for use in the LDA+U method of Anisimov and collaborators. Our objectives are to make the method more firmly based, to concentrate primarily on ground state properties rather than spectra, and to test the method in cases where only modest changes in orbital occupations are expected, as well as for highly correlated materials. Because of these objectives, we employ a differential definition of U. We also define a matrix U, which we find is very dependent on the environment of the atom in question. The formulation is applied to evaluate U for transition metal monoxides from VO to NiO using a local orbital basis set. The resulting values of U are typically only 40-65% as large as values currently in use. We evaluate the U matrix for the e_g and t_{2g} subshells in paramagnetic FeO, and illustrate the very different charge response of the e_g and t_{2g} states. The sensitivity of the method to the choice of the d orbitals, and to the basis set in general, is discussed.Comment: 6 figure

Highly fluorinated polyurethanes

The reaction perfluorinated hydroxyl terminated polyether with diisocyanate to form polyurethane is discussed. Data are given on the resin's oxidation stability, chemical resistance, and low temperature flexibility

Preparation of highly fluorinated polyurethanes

New polyurethanes, formed from a reaction of a prepolymer diol and a perfluorinated diisocyanate, are nonflammable and possess high corrosion resistance and good low temperature flexibility. Polymer hardness increases rapidly with increasing ratio of diisocaynate to diol, but its glass transition temperature is not adversely affected

Hydroxy terminated perfluoro ethers Patent

Chemical synthesis of hydroxy terminated perfluoro ethers as intermediates for highly fluorinated polyurethane resin

Preparation of highly fluorinated diols containing ether linkages.

Hydroxy-terminated perfluoroethers and polyurethane resins derived from ethers have outstanding chemical resistance and good thermal properties. They can be used as potting compounds, coatings, and seals. The hydroxy-terminated ethers serve as intermediates in the synthesis of highly fluorinated elastomers and adhesives

Preparation of perfluoropolyether prepolymers

Fluorinated prepolymers are used to generate highly fluorinated polymers which possess most of the desirable properties of polytetrafluoroethylene, such as nonflammability and high corrosion resistance, while retaining good low temperature flexibility

Trade Openness and Economic Performance of ECOWAS Members - Reflections From Ghana And Nigeria.

Trade openness is believed to stimulate economic growth due to its influence in integrating world economies and generating better markets. The study examined the impact of trade openness on economic performance of ECOWASMembers focusing on Ghana and Nigeria (1975-2004).Data sourced from IFS and others, were analyzed employing ADF/PP stationarity, cointegration and vector error correction techniques. A unique long-run relationship between economic performance, trade openness, real government expenditure, labour force and real capital stock for both Ghana and Nigeria was established, while about 88.9"10 and 83.1"10 errors made in the previous period were found to be corrected in the current period for the respective countries. In addition, trade openness and real government expenditure impact positively the economies of Ghana and Nigeria. However, the effectswere higher in the former than the latter

FOREIGN CAPITAL AND AFRICA’S ECONOMIC PROGRESS: FACTS FROM NIGERIA AND SOUTH AFRICA

Foreign capital inflow is usually believed as a means of supplementing domestic capital. The paper examined the influence of foreign capital on Africa’s economic progress focusing on Nigeria and South Africa (1970-2004). Data sourced from IFS, CBN and others were analyzed with econometric techniques. Empirical facts from cointegration and Granger casualty tests are as follows: There is a long-run relationship between foreign capital and economic progress in South Africa but in Nigeria it is short-run oriented; Foreign capital Granger-causes economic progress in South Africa, while in Nigeria casualty runs on the reverse; a bi-directional causality exists between economic progress and domestic capital in South Africa, for Nigeria it is uni-directional running from domestic capital to economic progress; Labour force in both countries Granger-causes their economic progress. In the light of the above, foreign capital should be promoted in South Africa to enhance her economic progress while in Nigeria polices that can reduce the level of capital flight (e.g. dependable institutional framework etc) are essential for foreign capital to have long-run influence on her economic progress. The need for the countries to rely more on domestic capital is equally suggested as viable factors for their economic progress