A first principles study of the distribution of iron in sphalerite

Quantum mechanical techniques, based on density functional theory, have been used to study the distribution of iron impurities in sphalerite (ZnS) at compositions ranging from 3.125 to 12.5 mol% FeS. Our results show that iron is most easily incorporated by direct substitution onto the zinc site and that energies for solution reactions involving FeS are exothermic when the system is zinc deficient. Furthermore, there appears to be a small driving force for the formation of bound Fe? Fe pairs at low iron concentrations, though there is no particular preference found for larger clusters of iron. The influence of iron on the sphalerite cell parameter is shown to be sensitive to the presence of Fe-Fe pairs and to the degree of sample non-stoichiometry

Introgression of Brown Norway \u3cem\u3eCYP4A\u3c/em\u3e Genes onto the Dahl Salt-Sensitive Background Restores Vascular Function in SS-5\u3csup\u3eBN\u3c/sup\u3e Consomic Rats

The present study tested the hypothesis that the Dahl SS (salt-sensitive) rat has vascular dysfunction due, in part, to the up-regulation of the CYP4A/20-HETE (cytochrome P450 ω-hydroxylase 4A)/20-hydroxyeicosatetraenoic acid) system. To assess the role of vascular 20-HETE, SS rats were compared with SS-5BN consomic rats, carrying CYP4A alleles on chromosome 5 from the normotensive BN (Brown Norway) introgressed on to the SS genetic background. Cerebral arteries from SS-5BN rats had less CYP4A protein than arteries from SS rats fed either NS (normal-salt, 0.4% NaCl) or HS (high-salt, 4.0% NaCl) diet. ACh (acetylcholine)-induced dilation of MCAs (middle cerebral arteries) from SS and SS-5BN rats was present in SS-5BN rats fed on either an NS or HS diet, but absent in SS rats. In SS rats fed on either diet, ACh-induced dilation was restored by acute treatment with the CYP4A inhibitor DDMS (N-methyl-sulfonyl-12,12-dibromododec-11-enamide) or the 20-HETE antagonist 20-HEDE [20-hydroxyeicosa-6(Z),15(Z)-dienoic acid]. The restored response to ACh in DDMS-treated SS rats was inhibited by L-NAME (NGnitro-L-arginine methyl ester) and unaffected by indomethacin or MS-PPOH [N-methylsulfonyl-6-(2-propargyloxyphenyl)hexanamide]. Vascular relaxation responses to the NO donor C5FeN6Na2O were intact in both SS and SS-5BN rats and unaffected by the acute addition of DDMS, indicating that the vascular dysfunction of the SS rat is due to a reduced bioavailability of NO instead of failure of the VSMCs (vascular smooth muscle cells) to respond to the vasodilator. Superoxide levels in cerebral arteries of SS-5BN rats [evaluated semi-quantitatively by DHE (dihydroethidium) fluorescence] were lower than those in the arteries of SS rats. These findings indicate that SS rats have an up-regulation of the CYP4A/20-HETE pathway resulting in elevated ROS (reactive oxygen species) and reduced NO bioavailability causing vascular dysfunction

Atomistic simulation of Mg2SiO4 and Mg2GeO4 spinels: a new model

We have developed a new interatomic potential model for the simulation of ringwoodite, the high-pressure phase of Mg2SiO4, and its low-pressure analogue, Mg2GeO4 spinel. The main novelty is the addition of a breathing shell model that enables us to accurately describe the structural and elastic parameters of both spinels up to 15PGs. Our model has also been applied to the two other Mg2SiO4 polymorphs in order to test its transferability. We find that although it is able to reproduce the structure and physical properties of wadsleyite, the breathing shell description is less successful with forsterite. the Mott-Littleton method has been used to calculate the energy of the intrinsic point defects in both spinels. The results indicate that these phases are likely to have the same defect population with teh MgO partial Schottky defect predominating

Kathleen Randles, Mezzo-Soprano Julian Dawson, Piano

Kemp Recital Hall Sunday Evening February 27, 1994 8:00p.m

The Perils of Pandemic Exceptionalism

In response to the pandemic, most states have enacted special measures to protect national economies and public health. Many of these measures would likely violate trade and investment disciplines unless they qualify for one of several exceptions. This Essay examines the structural implications of widespread anticipated defenses premised on the idea of “exceptionalism.” It argues that the pandemic reveals the structural weakness of the exceptions-oriented paradigm of justification in international economic law

Music of Erik Satie: Kathleen Randles, Mezzo-Soprano Julian Dawson, Piano

CV A Gallery I Tuesday Evening January 26, 1993 7:00p.m

Drivers of Sediment Transport Across the Entrance to the Gippsland Lakes, Australia

Water Qualit

Telecentre functionality in South Africa: re-enabling the community ICT access environment

Despite the availability and capabilities of Information and Communication Technologies (ICT) in low and middle-income countries, the use of these constantly evolving tools remains limited for the majority of resource-poor citizens. This is especially the case for internet-based tools. In South Africa, an upper middle-income country, the percentage of the population categorised as individual 'internet users' increased from 5.4 percent in 2000 to just 18.0 percent in 2010 (ITU, 2011). In order to overcome these low percentages, government intervention is frequently adopted, especially in rural areas, where it is not profitable for telecommunication operators to build infrastructure as a means to promote the uptake of internet use in poorer communities (USAASA, 2009: 47). In South Africa and elsewhere, government sponsored telecentres are a common non-profit mode of delivery, however there is much evidence of recurring problems (Gomez et al., 2012). Telecentres have many structural components (human, political and technical) which need to support each other in order to create a functional telecentre (Benjamin, 2001a; Heeks, 2002; Proenza, 2002). The failure of one or more of these components, as detailed by Roman & Colle (2002), Hulbert & Snyman (2007), and Parkinson (2005) can render telecentres non-functional. Such failures continue to plague the delivery of Public Access Computing (PAC) services in South Africa and elsewhere; and in the light of the growth of smartphones, it could be argued that telecentres are not a meaningful mode through which internet access can be delivered (Chigona et al., 2011; Gomez et al., 2012). However, ICT4D has lacked a robust theoretical base (Flor, 2012; Urquhart et al., 2008) and the literature has been dominated by a rather 'structuralist' and supply-side approach with less attention to individual agency and the demand-side. By considering how elements of agency and structure combine in relation to ICTs, the Choice Framework (CF) developed by Kleine (2010) is a step forward. This approach facilitates the analyses of people's varied ability to empower themselves and improve their quality of life (QoL). Using this Framework, this article analyses the operational experiences of telecentre provision of computer and internet access, alongside user experiences that reveal how telecentre and other structural issues interact with the characteristics of users and their various sets of resources. Based on this analysis, we suggest that PACs should remain a part of the ICT debate, although we question the business model that has come to dominate their operation.International Bibliography of Social Science