Interplay of Chemical Bonding and Magnetism in Fe_4N, Fe_3N, Fe_2N

Using spin density functional theory we have carried out a comparative study of chemical bonding and magnetism in Fe_4N, Fe_3N and Fe_2N. All of these compounds form close packed Fe lattices, while N occupies octahedral interstitial positions. High spin fcc Fe and hypothetical FeN with rock salt structure have been included in our study as reference systems. We find strong, covalent Fe-N bonds as a result of a substantial \sigma-type p-d hybridisation, with some charge transfer to N. Those Fe d orbitals which contribute to the p-d bonds, do no longer participate in the exchange splitting of the Fe d bands. Because of the large exchange fields, the majority spin d bands are always fully occupied, while the minority spin d bands are close to half-filling, thus optimizing the Fe d-d covalent bonding. As a consequence, in good approximation the individual Fe moments decrease in steps of 0.5 \mu_B from fcc iron (2.7 \mu_B) via Fe_4N (2.7 and 1.97 mu_B}), \chem{Fe_3N} (1.99 \mu_B) to \zeta - Fe_2N (1.43 \mu_B).Comment: 16 pages, 15 figure

FARM-HOUSEHOLD ANALYSIS OF POLICIES AFFECTING PEANUT PRODUCTION IN SENEGAL

A farm-level survey of 150 households was conducted in the peanut basin of Senegal, and a profit function system estimated, for the purpose of analyzing the effects of policies affecting the peanut sector. Producer price of peanuts has relatively little effect on production, but producer price of millet influences peanut seed demand.Agricultural and Food Policy, Demand and Price Analysis,

Cash Crop and Foodgrain Productivity in Senegal: Historical View, New Survey Evidence, and Policy Implications

Crop Production/Industries, Productivity Analysis, Downloads July 2008 - June 2009: 10,

Cycles of construing in radicalization and deradicalization: a study of Salafist Muslims.

© Taylor & Francis Group, LLC.This article explores radicalization and deradicalization by considering the experiences of six young Tunisian people who had become Salafist Muslims. Their responses to narrative interviews and repertory grid technique are considered from a personal construct perspective, revealing processes of construing and reconstruing, as well as relevant aspects of the structure and content of their construct systems. In two cases, their journeys involved not only radicalization but self-deradicalization, and their experiences are drawn on to consider implications for deradicalization.Peer reviewedFinal Accepted Versio

Assessment of power plant emission and its health impact in Gaza

The aim of study was to investigate the concentrations of the ambient air pollutants (i.e PM2.5, CO, CO2) and to examine the health impacts on the residentials living surrounding the power plant in Gaza City-Palestine.The pollutants were monitored several distance surrounding the plant for a period of four months during both summer and winter seasons using a portable laser particle counter and gaseous monitor. A public health questionnaire was also distributed on the residents living around the power plant in order to assess the impact of air pollution on their health status.The results showed that the concentration of particulate matter exceeded the WHO standard where the highest level was 79 ?g/m3 and the lowest level was 49?g/m3. However the concentration of carbon monoxide was lower than the WHO standards where the highest level was 2.18 ppm and lowest level was 0.1 ppm. Moreover, the concentration of carbon dioxide oscillated from 254 ppm to 514 ppm. The health assessment results showed that 50% of the study sample suffered of breathing difficulties.This study concluded that the concentration of particulate matter and carbon dioxide were high, while the level of carbon monoxide was low, furthermore the level of public awareness was good. Meanwhile 40% of population sample visited the hospital because of a disease that infects the respiratory tract

Accurate low-order modeling of electrified falling films at moderate Reynolds number

The two- and three-dimensional spatio-temporal dynamics of a falling, electrified leaky dielectric film are studied. The method of weighted residuals is used to derive high-order models that account for both inertia as well as second-order electrostatic effects. The models are validated against both linear theory and direct numerical simulations of the Navier-Stokes equations. It is shown that a simplified model offers a rapid computational option at the cost of a minimal decrease in accuracy. This model is then used to perform a parametric study in three dimensions

Reduced models for thick liquid layers with inertia on highly curved substrates

A method is presented for deriving reduced models for fluid flows over highly curved substrates with wider applicability and accuracy than existing models in the literature. This is done by reducing the Navier-Stokes equations to a novel system of boundary layer like equations in a general geometric setting. This is accomplished using a new, relaxed set of scalings that assert only that streamwise variations are ‘slow’. These equations are then solved using the method of weighted residuals, which is demonstrated to be applicable regardless of the geometry selected. A large number of results in the literature can be derived as special cases of our general formulation. A few of the more interesting cases are demonstrated. Finally, the formulation is applied to two thick annular flow systems as well as a conical system in both linear and nonlinear regimes, which traditionally has been considered inaccessible to such reduced models. Comparisons are made with direct numerical simulations of the Stokes equations. The results indicate that reduced models can now be used to model systems involving thick liquid layers

First principles investigations of the electronic, magnetic and chemical bonding properties of CeTSn (T=Rh,Ru)

The electronic structures of CeRhSn and CeRuSn are self-consistently calculated within density functional theory using the local spin density approximation for exchange and correlation. In agreement with experimental findings, the analyses of the electronic structures and of the chemical bonding properties point to the absence of magnetization within the mixed valent Rh based system while a finite magnetic moment is observed for trivalent cerium within the Ru-based stannide, which contains both trivalent and intermediate valent Ce.Comment: 6 pages, 7 figures, for more information see http://www.physik.uni-augsburg.de/~eyert

Direct observation of nuclear reorganization driven by ultrafast spin transitions

One of the most basic molecular photophysical processes is that of spin transitions and intersystem crossing between excited states surfaces. The change in spin states affects the spatial distribution of electron density through the spin orbit coupling interaction. The subsequent nuclear reorganization reports on the full extent of the spin induced change in electron distribution, which can be treated similarly to intramolecular charge transfer with effective reaction coordinates depicting the spin transition. Here, single-crystal [FeII(bpy)3] (PF6)2, a prototypical system for spin crossover (SCO) dynamics, is studied using ultrafast electron diffraction in the single-photon excitation regime. The photoinduced SCO dynamics are resolved, revealing two distinct processes with a (450 ± 20)-fs fast component and a (2.4 ± 0.4)-ps slow component. Using principal component analysis, we uncover the key structural modes, ultrafast Fe–N bond elongations coupled with ligand motions, that define the effective reaction coordinate to fully capture the relevant molecular reorganization