Tuning the metal-to-metal charge transfer energy of cyano-bridged dinuclear complexes

The metal-to-metal charge transfer (MMCT) transitions of a series of Class II mixed valence dinuclear complexes bearing cyano bridging ligands may be varied systematically by variations to either the hexacyanometallate(II) donor or Co-III acceptor moieties. Specifically, the new dinuclear species trans-[(LCoNCFe)-Co-14S(CN)(5)](-) (L-14S = 6-methyl-1,11-diaza-4,8-dithia- cyclotetradecane-6-amine) and trans-[(LCoNCRu)-Co-14(CN)(5)]-(L-14 = 6-methyl-1,4,8,11-tetraazacyclotetradecane-6-amine) have been prepared and their spectroscopic and electrochemical properties are compared with the relative trans-[(LCoNCFe)-Co-14(CN)(5)](-). The crystal structures of Na{trans-[(LCoNCFe)-Co-14S(CN)(5)]}.51/2H(2)O.1/2EtOH, Na{trans-[(LCoNCRu)-Co-14(CN)(5)]}.3H(2)O and Na{trans-[(LCoNCRu)-Co-14(CN)(5)]}.8H(2)O are also reported. The ensuing changes to the MMCT energy have been examined within the framework of Hush theory, and it was found that the free energy change between the redox isomers was the dominant effect in altering the energy of the MMCT transition.

Phosphate forms an unusual tripodal complex with the Fe-Mn center of sweet potato purple acid phosphatase

Purple acid phosphatases (PAPs) are a family of binuclear metalloenzymes that catalyze the hydrolysis of phosphoric acid esters and anhydrides. A PAP in sweet potato has a unique, strongly antiferromagnetically coupled Fe(III)-Mn(II) center and is distinguished from other PAPs by its increased catalytic efficiency for a range of activated and unactivated phosphate esters, its strict requirement for Mn(II), and the presence of a mu-oxo bridge at pH 4.90. This enzyme displays maximum catalytic efficiency (k(cat)/K-m) at pH 4.5, whereas its catalytic rate constant (k(cat)) is maximal at near-neutral pH, and, in contrast to other PAPs, its catalytic parameters are not dependent on the pK(a) of the leaving group. The crystal structure of the phosphate-bound Fe(III)-Mn(II) PAP has been determined to 2.5-Angstrom resolution (final R-free value of 0.256). Structural comparisons of the active site of sweet potato, red kidney bean, and mammalian PAPs show several amino acid substitutions in the sweet potato enzyme that can account for its increased catalytic efficiency. The phosphate molecule binds in an unusual tripodal mode to the two metal ions, with two of the phosphate oxygen atoms binding to Fe(III) and Mn(II), a third oxygen atom bridging the two metal ions, and the fourth oxygen pointing toward the substrate binding pocket. This binding mode is unique among the known structures in this family but is reminiscent of phosphate binding to urease and of sulfate binding to A protein phosphatase. The structure and kinetics support the hypothesis that the bridging oxygen atom initiates hydrolysis.

Microstructure control in Sn-0.7mass%Cu alloys

Soldering alloys based oft the Sn-Cu alloy system are amongst the most favourable lead-free alternatives due to a range of attractive properties. Trace additions of Ni have been found to significantly improve the soldering characteristics of these alloys (reduced bridging etc.). This paper examines the mechanisms underlying the improvement in soldering properties of Sn-0.7 mass%Cu eutectic alloys modified with concentrations of Ni ranging front 0 to 1000 ppm. The alloys were investigated by thermal analysis during solidification, as well as optical/SEM microanalyses of fully solidified samples anti samples quenched during solidification. It is concluded that Ni additions dramatically alter the nucleation patterns and solidification behaviour of the Sn-Cu6Sn5 eutectic anti that these changes are related to the superior soldering characteristics of the Ni-modified Sn-0.7 mass%Cu alloys.

Synthetic, EPR spectroscopic, magnetic and X-ray crystallographic structural studies on copper(II) complexes of the tridentate N2S donor ligand formed from 6-methyl-2-formylpyridine and S-methyldithiocarbazate (Hmpsme)

New copper(II) complexes of general empirical formula, Cu(mpsme)X center dot xCH(3)COCH(3) (mpsme = anionic form of the 6-methyl-2-formylpyridine Schiff base of S-methyldithiocarbazate; X = Cl, N-3, NCS, NO3; x = 0, 0.5) have been synthesized and characterized by IR, electronic, EPR and susceptibility measurements. Room temperature mu(eff) values for the complexes are in the range 1.75-2.1 mu(beta) typical of uncoupled or weakly coupled Cu(II) centres. The EPR spectra of the [Cu(mpsme)X] (X = Cl, N-3, NO3, NCS) complexes reveal a tetragonally distorted coordination sphere around the mononuclear Cu(II) centre. We have exploited second derivative EPR spectra in conjunction with Fourier filtering (sine bell and Hamming functions) to extract all of the nitrogen hyperfine coupling matrices. While the X-ray crystallography of [Cu(mpsme)NCS] reveals a linear polymer in which the thiocyanate anion bridges the two copper(II) ions, the EPR spectra in solution are typical of a magnetically isolated monomeric Cu(II) centres indicating dissociation of the polymeric chain in solution. The structures of the free ligand, Hmpsme and the {[Cu(mpsme)NO3] center dot 0.5CH(3)COCH(3)}(2) and [Cu(mpsme)NCS](n) complexes have been determined by X-ray diffraction. The {[Cu(mpsme)NO3]0.5CH(3)COCH(3)}(2) complex is a centrosymmetric dimer in which each copper atom adopts a five-coordinate distorted square-pyramidal geometry with an N2OS2 coordination environment, the Schiff base coordinating as a uninegatively charged tridentate ligand chelating through the pyridine and azomethine nitrogen atoms and the thiolate, an oxygen atom of a unidentate nitrato ligand and a bridging sulfur atom from the second ligand completing the coordination sphere. The [Cu(mpsme)(NCS)](n) complex has a novel staircase-like one dimensional polymeric structure in which the NCS- ligands bridge two adjacent copper(II) ions asymmetrically in an end-to-end fashion providing its nitrogen atom to one copper and the sulfur atom to the other. (c) 2005 Elsevier B.V. All rights reserved.

Ab initio studies of hydrogen desorption from low index magnesium hydride surface

The low index Magnesium hydride surfaces, MgH2(001) and MgH2(110), have been studied by ab intio Density Functional Theory (DFT) calculations. It was found that the MgH2(110) surface is more stable than MgH2(001) surface, which is in good agreement with the experimental observation. The H-2 desorption barriers vary depending on the crystalline surfaces that are exposed and also the specific H atom sites involved-they are found to be generally high, due to the thermodynamic stability of the MgH2, system, and are larger for the MgH2(001) surface. The pathway for recombinative desorption of one in-plane and one bridging H atom from the MgH2(110) surface was found to be the lowest energy barrier amongst those computed (172 KJ/mol) and is in good agreement with the experimental estimates. (c) 2006 Elsevier B.V. All rights reserved.

Understanding sociocognitive space of written discourse: Implications for teaching business writing to Chinese students

Confronted with various issues in teaching business writing to Chinese students in New Zealand, this paper sees the need for bridging the gap between genre-based research and teaching in an intercultural context. Specifically, it develops an intercultural reflective model in the light of Bhatia's sociocognitive genre study as well as cross-cultural persuasion. As an important part of the model, New Zealand and Chinese experts' intracultural and intercultural reflections on business writing are solicited and compared and the theoretical implications for teaching and learning business writing are discussed. It has been found, through a case study of analysing English and Chinese business faxes, this model can offer an in-depth understanding about discursive competence across cultures, and provide a link between genre-based theory, teaching practice and professional expertise.

Mechanistic aspects of proton chain transfer: A computational study for the green fluorescent protein chromophore

We explore several models for the ground-state proton chain transfer pathway between the green fluorescent protein chromophore and its surrounding protein matrix, with a view to elucidating mechanistic aspects of this process. We have computed quantum chemically the minimum energy pathways (MEPs) in the ground electronic state for one-, two-, and three-proton models of the chain transfer. There are no stable intermediates for our models, indicating that the proton chain transfer is likely to be a single, concerted kinetic step. However, despite the concerted nature of the overall energy profile, a more detailed analysis of the MEPs reveals clear evidence of sequential movement of protons in the chain. The ground-state proton chain transfer does not appear to be driven by the movement of the phenolic proton off the chromophore onto the neutral water bridge. Rather, this proton is the last of the three protons in the chain to move. We find that the first proton movement is from the bridging Ser205 moiety to the accepting Glu222 group. This is followed by the second proton moving from the bridging water to the Ser205for our model this is where the barrier occurs. The phenolic proton on the chromophore is hence the last in the chain to move, transferring to a bridging “water” that already has substantial negative charge.

The role of social capital in the promotion of conservation farming: The case of 'landcare' in the southern Philippines

'Social capital' refers to the relationships of trust, communication, and cooperation that facilitate collective action in a community. It is particularly relevant to soil conservation in developing countries, which requires collective efforts to raise awareness of soil degradation, provide effective training in soil conservation practices, and implement soil conservation measures on individual farms. The Landcare Program in the Southern Philippines promotes simple conservation practices in upland environments through establishing and supporting community landcare groups and municipal landcare associations, thus augmenting the social capital of farmers in these locations. An evaluation of the Landcare Program in Barangay Ned, South Cotabato, based on a survey of 313 farm households and case studies of nine landcare groups, shows that, despite extreme isolation and difficult working conditions, farmers responded by rapidly forming landcare groups and a landcare association, and adopting contour barriers on their maize farms. They utilized the bonding social capital inhering in their local communities to build stocks of bridging social capital, linking them to information, training and resources from outside their immediate locality. A logistic regression model of the factors affecting adoption of contour barriers shows that farmers who had undergone the practical, farmer-based training provided by the Landcare Program, and who were members of a landcare group, were significantly more likely to adopt conservation measures. These results confirm the value of investing in social capital to promote soil conservation. Copyright (c) 2005 John Wiley & Sons, Ltd.

The Seduction of Sarah: travel memoirs and intercultural learning

The paper explores the nexus between intercultural storytelling and intercultural learning. Noting the wide appeal of the travel memoir set in France, it takes as a case study a book that, while positioned within that genre, attempts to shift some predictable patterns: Sarah Turnbull’s best-selling Almost French. Analysis shows that the book in fact participates in a subtle play of genres, whereby the lure of the travel memoir is used to entice readers towards a position where they read the book as a guide to French culture. The particular form of hybridity attempted is, however, a delicate enterprise, as the reception of the book demonstrates, in that the intercultural lessons on offer risk being overshadowed by the expectations readers bring to the genre of the travel memoir. The paper examines the competing seductions operating throughout the text and relates the conditions for taking up the opportunity for intercultural learning to questions of genre. It offers a pedagogical uptake of the textual analysis, thus bridging disciplines in a way that mirrors Turnbull’s bridging of genres

Effects of cation substitutions on the physical properties of M2M1T2O6 pyroxenes

In this PhD study, the effects of the cation substitutions on the physical properties of pyroxenes have been discussed. The results of this work extend the knowledge on pyroxenes with different chemical compositions. These properties might be used in the development of ceramic pigments, advanced materials and for the mineralogical phase identification. First of all, the crystallographic differences between Ge and Si pyroxenes have been examined. The structure of C2/c Ca rich Ge clinopyroxenes is very close to the low pressure C2/c structural configuration found in Ca-rich Si-pyroxenes. The shear of the unit cell is very similar, and the difference between a Ge end member and the corresponding Si-rich one is less than 1°. Instead, a remarkable difference exists between Ca-poor Si and Ge clinopyroxenes. First, Ca-poor Ge pyroxenes do not display a P21/c symmetry, but retain the C2/c symmetry; second, the observed C2/c structure shows, at room pressure, the configuration with highly kinked tetrahedral chains characteristic of the high pressure C2/c symmetry of Si Ca-poor pyroxenes. In orthopyroxenes, with Pbca symmetry, Ge-pyroxenes have volume larger than Si-pyroxenes. Samples along the system CaCoGe2O6 - CoCoGe2O6 have been synthesized at three different temperatures: 1050 °C, 1200 °C and 1250 °C. The aim of these solid state syntheses was to obtain a solid solution at ambient pressure, since the analogues Si-system needs high pressure. Unfortunately, very limited solution occurs because the structure forms of the two end member (high temperature for CaCoGe2O6 and high pressure CoCoGe2O6) are incompatible. The phase diagram of this system has been sketched and compared to that of Si. The cobalt end member (CoCoGe2O6) is stable at ambient pressure in two symmetries: at 1050 °C C2/c and 1200 °C Pbca. The impurity phase formed during these experiments is cobalt spinel. Raman spectroscopy has been used to investigate the vibrational properties of Ca-pyroxenes CaCoGe2O6, CaMgGe2O6, CaMgSi2O6 and CaCoSi2O6. A comparison between silicate and germanate pyroxenes shows significant changes in peak positions of the corresponding modes caused mainly by the difference of the Ge-Si atomic weight along with the distortion and compression of the coordination polyhedra. Red shift in Raman spectra of germanates has been calculated by a rough scale factor calculated by a simple harmonic oscillator model, considering the different bond lengths for 4-coordinated Si ~ 1.60- 1.65 Å vs Ge–O distance ~1.70 - 1.80 Å. The Raman spectra of CaMgGe2O6 and CaCoGe2O6 have been classified, in analogy with silicate (Wang et al., 2001) counterparts, in different ranges: - R1 (880-640 cm-1): strong T-O stretching modes of Ge and non-bridging O1 and O2 atoms within the GeO4 tetrahedron; - R2 (640-480 cm-1): stretching/bending modes of Ge-Obr-Ge bonds (chain stretching and chain bending); - R4 (480-360 cm-1): O-Ge-O vibrations; - R3 (360-240 cm-1): motions of the cations in M2 and M1 sites correlated with tetrahedral chain motion and tilting tetrahedra; - R5 (below 240 cm-1): lattice modes. The largest shift with respect to CaMgSi2O6 - CaCoSi2O6 is shown by the T-O stretching and chain modes. High-pressure Raman spectroscopy (up to about 8 GPa) on the same samples of Ca-pyroxenes using an ETH-type diamond anvil cell shows no phase transition within the P-ranges investigated, as all the peak positions vary linearly as a function of pressure. Our data confirm previous experimental findings on Si-diopside (Chopelas and Serghiou, 2000). In the investigated samples, all the Raman peaks shift upon compression, but the major changes in wavenumber with pressure are attributed to the chain bending (Ge-Obr-Ge bonds) and tetrahedra stretching modes (Ge-Onbr). Upon compression, the kinking angle, the bond lengths and T-T distances between tetrahedra decrease and consequently the wavenumber of the bending chain mode and tetrahedra stretching mode increases. Ge-pyroxenes show the higher P-induced peak-position shifts, being more compressible than corresponding silicates. The vibrational properties of CaM2+Ge2O6 (M2+ =Mg, Mn, Fe, Co, Ni, Zn) are reported for the first time. The wavenumber of Ge-Obr-Ge bending modes decreases linearly with increasing ionic radius of the M1 cation. No simple correlation has been found with M1 atomic mass or size or crystallographic parameters for the peak at ~850 cm-1 and in the low wavenumber regions. The magnetic properties of the system CaCoSi2O6 - CoCoSi2O6 have been investigated by magnetometry. The join is always characterized by 1 a.p.f.u. of cobalt in M1 site and this causes a pure collinear antiferromagnetic behaviour of the intra-chain superexchange interaction involving Co ions detected in all the measurements, while the magnetic order developed by the cobalt ions in M2 site (intra-chain) is affected by weak ferromagnetism, due to the non-collinearity of their antiferromagnetic interaction. In magnetically ordered systems, this non-collinearity effect promotes a spin canting of anti-parallel aligned magnetic moments and thus is a source of weak ferromagnetic behaviour in an antiferromagnetic. The weak ferromagnetism can be observed only for the samples with Co content higher than 0.5 a.p.f.u. in M2, when the concentration is sufficiently high to create a long range order along the M2 chain which is magnetically independent of M1 chain. The ferromagnetism was detected both in the M(T) at 10 Oe and M(H).

A INCLUSÃO SOCIAL E AS MEDIAÇÕES NA RECEPÇÃO DA COMUNICAÇÃO MERCADOLÓGICA TELEVISIVA POR PESSOAS COM DEFICIÊNCIA VISUAL

Este trabalho é estimulado pela reflexão sobre a recepção da comunicação mercadológica televisiva por pessoas com deficiência visual, assim como sobre a percepção quanto às iniciativas do governo e das empresas em prol da inclusão. O estudo busca, com base na Teoria das Mediações, que é estudada por teóricos dos Estudos de Recepção, entender de que forma as pessoas com deficiência visual interagem com as diferentes categorias de comerciais de televisão, a partir de seus valores, percepções de mundo e condições em que se encontram. Deste modo, observa-se ainda o nível de sentimento de pertencimento das pessoas com deficiência visual quanto à preocupação do governo e das empresas em causas sociais. Os procedimentos que dirigem a investigação caracterizam-se por uma reflexão a partir de dados decorrentes de pesquisa bibliográfica, articulada a uma pesquisa de campo de natureza qualitativa. O trabalho conclui que a percepção das pessoas com deficiência visual se distancia do que está sendo proposto, feito e aparentemente sendo bem divulgado em prol da inclusão; bem como, observa a necessidade de aprimoramento da conscientização da sociedade, e consequentemente dos comunicadores, sobre a importância da aproximação entre as pessoas com deficiência visual e a comunicação mercadológica televisiva. Nesta percepção, o trabalho apresenta sugestões no âmbito comunicacional que poderiam tornar as causas sociais realmente expressivas na vida das pessoas com deficiência visual.

The UK productivity gap in the service sector: do management practices matter?

Purpose – This paper aims to contribute to the debate on the drivers of the productivity gap that exists between the UK and its major international competitors. Design/methodology/approach – From the macro perspective the paper explores the quantitative evidence on the productivity differentials and how they are measured. From the micro perspective, the article explores the quantitative evidence on the role of management practices claimed to be a key determinant in promoting firm competitiveness and in bridging the UK gap. Findings – This study suggests that management practices are an ambiguous driver of firm productivity and higher firm performance. On the methodological side, qualitative and subjective measures of either management practices or firm performance are often used. This makes the results not comparable across studies, across firms or even within firms over time. Productivity and profitability are often and erroneously interchangeably used while productivity is only one element of firm performance. On the other hand, management practices are multi-dimensional constructs that generally do not demonstrate a straightforward relationship with productivity variables. To assume that they are the only driver of higher productivity may be misleading. Moreover, there is evidence of an inverse causal relationship between management practices and firm performance. This calls into question most empirical results of the extant literature based on the unidirectional assumption of direct causality between management practices and firm performance. Research limitations/implications – These and other issues suggest that more research is needed to deepen the understanding of the UK productivity gap and more quantitative evidence should be provided on the way in which management practices contribute to the UK competitiveness. Their impact is not easily measurable due to their complexity and their complementary nature and this is a fertile ground for further research. Originality/value – This paper brings together the evidence on the UK productivity gap and its main drivers, provided by the economics, management and performance measurement literature. This issue scores very highly in the agenda of policy makers and academics and has important implications for practitioners interested in evaluating the impact of managerial best practices.

Babies, bodies and entitlement: gendered aspects of access to citizenship in the Republic of Ireland

Since the mid-1990s, automatic citizenship for children born in the Republic has been a source of growing debate against a backdrop of increasing immigration and the peace process. In June 2004, the debate culminated in a referendum, opening the way to a constitutional amendment that attaches residence qualifications to the hitherto unfettered entitlement to citizenship available through ius soli. Arguments for the amendment were couched in terms of a threat posed by Third World women having babies in Ireland to obtain residence, and a putative obligation to the EU to harmonise citizenship laws. This article explores how pregnant foreign women’s bodies became a site of perplexity about the borders of the twenty-first century Irish nation. It is therefore suggested that neither the ‘racial state’ theories nor feminist theories of the nation-state account fully for this. On closer inspection, the seemingly sui generis case of the Irish referendum is therefore fruitful in that it demands further reflection in terms of bridging gaps in the existing theory.

Does ICT promote democracy and economic freedom in Middle East?

This study investigates the impact of information and communication technology (ICT) expansion on economic and social freedom in the Middle East (Bahrain, Iran, Jordan, Kuwait, Lebanon, Oman, Qatar, Saudi Arabia, Syria and United Arab Emirates) for the period of 1996 to 2005. This study is unique as it analyzes the effect of institutional resistance (governments’ restrictions) on ICT development, economic freedom and democracy. The results show that institutional resistance poses a significant negative effect on ICT development and democracy. Results also show that ICT expansion in Middle East has not only been effective in bridging the Digital Divide, but that it had a positive impact on promoting civil liberties and economic freedom in a region that is vulnerable to political, social, and global conflicts.

The impact of information and communication technology (ICT), education and regulation on economic freedom in Islamic Middle Eastern countries

Our study investigated the impact of ICT expansion on economic freedom in the Middle East (Bahrain, Iran, Jordan, Kuwait, Lebanon, Oman, Qatar, Saudi Arabia, Syria, United Arab Emirates, and Yemen). Our empirical analysis used archival data from 1995 to 2005; it showed that ICT expansion in the Middle East has been effective both in bridging the digital divide and also in promoting economic freedom in a region that was vulnerable to political, social, and global conflict. However, differences between countries, such as the educational attainment of their citizens and institutional resistance to technology acceptance, both enhanced and restricted the relationship between ICT and economic freedom.