In surface science, rutile TiO2 continues to be one of the most studied surfaces and in the catalysis field numerous groups study how adsorbates interact with this surface. All groups face the difficult problem of reproducibility due to surface preparation unknowns like defect concentration and the continuous aging of the crystals. Recent studies, using STM imaging, showed that hydroxyl adsorption takes place even in very good vacuum conditions. Upon adsorption, the surface electric field is reduced and the work function decreases. We found that this change may be readily detected in the onset energy of the secondary electrons. By following the onset region of secondary electron emission it is possible to track hydroxyl adsorption in quantities well below the detection level of XPS and LEIS. With this knowledge, we show that the time elapsed after surface preparation and water partial pressure should be accounted in the study of TiO2 surfaces.

{A new rigid bidentate ligand, bis(1-naphthylimino)acenaphthene, L1, and its Zn(II) and Pd(II) complexes {[}ZnCl(2)(L1)], 1, and {[}PdCl(2)(L1)], 2, were synthesized. L1 was prepared by the ``template method{''}, reacting 1-naphthyl amine and acenaphthenequinone in the presence of ZnCl(2), giving 1, which was further demetallated. Reaction of 1-naphthyl amine with acenaphthenequinone and PdCl(2) afforded dichloride bis(1-naphthyl)acenaphthenequinonediimine palladium, 2. L1, 1, and 2 were obtained as a mixture of syn and anti isomers. Compound 2 was also obtained by the reaction of PdCl(2) activated by refluxing it in acetonitrile followed by the addition of L1; by this route also a mixture of syn and anti isomers was obtained, but at a different rate. The solid-state structures of L1 and the anti isomer of compound 2 have been determined by single-crystal X-ray diffraction. All compounds have been characterized by elemental analyses; matrix-assisted laser desorption ionization-time-of-flight-mass spectrometry; IR; UV-vis; (1)H, (13)C, and (1)H-(1)H correlation spectroscopy; (1)H-(13)C heteronuclear single quantum coherence; (1)H-(13)C heteronuclear single quantum coherence-total correlation spectroscopy; and (1)H-(1)H nuclear Overhauser effect spectrometry NMR spectroscopies when applied. Density functional theory studies showed that both conformers for {[}PdCl(2)(BIAN)] are isoenergetic, and they can both be obtained experimentally. However, we can predict that the isomerization process is not available in a square-planar complex, but it is possible for the free ligand. The molecular geometry is very similar in both isomers, and only different orientations for naphthyl groups can be expected.}

{A stochastic representation for the solutions of the Poisson-Vlasov equation is obtained. The representation involves both an exponential and a branching process. The stochastic representation, besides providing an alternative existence proof and an intuitive characterization of the solutions, may also be used to obtain an intrinsic definition of the fluctuations. (c) 2007 Elsevier B.V. All rights reserved.}

{We consider a positive distribution Phi such that Phi defines a probability measure mu = mu Phi on the dual of some real nuclear Frechet space. A large deviation principle is proved for the family \{mu(n), n >= 1\} where mu(n) denotes the image measure of the product measure mu(n)(Phi) under the empirical distribution function L(n). Here the rate function I is defined on the space F(theta)'(N')(+) and agrees with the relative entropy function (H) over tilde (Psi/Phi). As an application, we cite the Gibbs conditioning principle which describes the limiting behaviour as n tends to infinity of the law of k tagged particles Y(1),...,Y(k) under the constraint that L(n)(Y) belongs to some subset A(0).}

Os motores de histerese são muito atraentes, numa ampla gama de aplicações devido à característica binário - velocidade e simplicidade de construção. É esperado que o rendimento destes motores seja melhorado aquando do uso de materiais supercondutores de alta temperatura (SAT ? supercondutores de alta temperatura) e, de facto, os motores de histerese têm-se mostrado como, provavelmente, a melhor máquina eléctrica usando materiais SAT. Ambos os motores, quer convencional quer supercondutor (com SAT), são motores de histerese, mas apresentam diferentes fenómenos físicos para o seu funcionamento: o comportamento de histerese nos materiais ferromagnéticos convencionais é devido à falta de linearidade das suas propriedades magnéticas dos materiais ferromagnéticos enquanto a histerese nos materiais supercondutores de alta temperatura é de natureza ohmica e está relacionada com dinâmica de vórtices. Nesta tese aspectos teóricos, experimentais e simulados de ambos os motores são discutidos, realçando-se o princípio de funcionamento de cada um e as características mais relevantes de cada um. As características obtidas, quer por testes experimentais quer por uso do simulador usando elementos finitos (FLUX2D?), foram comparadas com o objectivo de avaliar o rendimento dos motores electromecânicos e a eficiência dos sistemas, incluindo a criogenia para os dispositivos supercondutores de alta temperatura.

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The multicopper enzyme nitrous oxide reductase (N2OR) catalyzes the final step of denitrification, the two-electron reduction of N2O to N-2. This enzyme is a functional homodimer containing two different multicopper sites: CuA and CuZ. CuA is a binuclear copper site that transfers electrons to the tetranuclear copper sulfide CuZ, the catalytic site. In this study, Pseudomonas nautica cytochrome C-552 was identified as the physiological electron donor. The kinetic data show differences when physiological and artificial electron donors are compared [cytochrome vs methylviologen (MV)]. In the presence of cytochrome c(552), the reaction rate is dependent on the ET reaction and independent of the N2O concentration. With MV, electron donation is faster than substrate reduction. From the study of cytochrome c(552) concentration dependence, we estimate the following kinetic parameters: K-mc512 = 50.2 +/- 9.0 mu M and V-maxc551 1.8 +/- 10.6 units/mg. The N2O concentration dependence indicates a K-mN2O of 14.0 +/- 2.9 mu M using MV as the electron donor. The pH effect on the kinetic parameters is different when MV or cytochrome c(552) is used as the electron donor (pK(a) = 6.6 or 8.3, respectively). The kinetic study also revealed the hydrophobic nature of the interaction, and direct electron transfer studies showed that CuA is the center that receives electrons from the physiological electron donor. The formation of the electron transfer complex was observed by H-1 NMR protein-protein titrations and was modeled with a molecular docking program (BiGGER). The proposed docked complexes corroborated the ET studies giving a large number of solutions in which cytochrome c(552) is placed near a hydrophobic patch located around the CuA center.

1st ISA Forum report

In this paper will be discussed different types of scenarios and the aims for using scenarios. Normaly they are being used by organisations due to the need to anticipate processes, to support policy-making and to understand the complexities of relations. Such organisations can be private companies, R&D organisations and networks of organisations, or even by some public administration institutions. Some cases will be discussed as the methods for ongoing scenario-building process (Shell Internacional). Scenarios should anticipate possible relations among social actors as in the Triple Helix Model, and is possible to develop strategic intelligence in the innovation process that would enable the construction of scenarios. Such processes can be assessed. The focus will be made in relation to the steps chosen for the WORKS scenarios. In this case is there a model of work changes that can be used for foresight? Differences according to sectors were found, as well on other dimensions. Problems of assessment are analysed with specific application to the scenario construction methods.

No abstract is available for this item.

WORKS final conference report

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Membrane-bound nitrate reductase from Marinobacter hydrocarbonoclasticus 617 can be solubilized in either of two ways that will ultimately determine the presence or absence of the small (I) subunit. The enzyme complex (NarGHI) is composed of three subunits with molecular masses of 130, 65, and 20 kDa. This enzyme contains approximately 14 Fe, 0.8 Mo, and 1.3 molybdopterin guanine dinucleotides per enzyme molecule. Curiously, one heme b and 0.4 heme c per enzyme molecule have been detected. These hemes were potentiometrically characterized by optical spectroscopy at pH 7.6 and two noninteracting species were identified with respective midpoint potentials at E(m) = + 197 mV (heme c) and-4.5 mV (heme b). Variable-temperature (4-120 K) X-band electron paramagnetic resonance (EPR) studies performed on both as-isolated and dithionite-reduced nitrate reductase showed, respectively, an EPR signal characteristic of a {[}3Fe-4S](+) cluster and overlapping signals associated with at least three types of {[}4Fe-4S](+) centers. EPR of the as-isolated enzyme shows two distinct pH-dependent Mo(V) signals with hyperfine coupling to a solvent-exchangeable proton. These signals, called ``lowpH'' and ``high-pH,'' changed to a pH-independent Mo(V) signal upon nitrate or nitrite addition. Nitrate addition to dithionite-reduced samples at pH 6 and 7.6 yields some of the EPR signals described above and a new rhombic signal that has no hyperfine structure. The relationship between the distinct EPR-active Mo(V) species and their plausible structures is discussed on the basis of the structural information available to date for closely related membrane-bound nitrate reductases.

Direct electrochemical response was first time observed for the redox centers of Desulfovibrio gigas [NiFe]-Hase, in non-turnover conditions, by cyclic voltammetry, in solution at glassy carbon electrode. The activation of the enzyme was achieved by reduction with H(2) and by electrochemical control and electrocatalytic activity was observed. The inactivation of the [NiFe]-Hase was also attained through potential control. All electrochemical data was obtained in the absence of enzyme inhibitors. The results are discussed in the context of the proposed mechanism currently accepted for activation/inactivation of [NiFe]-Hases. (C) 2008 Elsevier B.V. All rights reserved.

Metalloenzymes control enzymatic activity by changing the characteristics of the metal centers where catalysis takes place. The conversion between inactive and active states can be tuned by altering the coordination number of the metal site, and in some cases by an associated conformational change. These processes will be illustrated using heme proteins (cytochrome c nitrite reductase, cytochrome c peroxidase and cytochrome cd(1) nitrite reductase), non-heme proteins (superoxide reductase and [ NiFe]-hydrogenase), and copper proteins (nitrite and nitrous oxide reductases) as examples. These examples catalyze electron transfer reactions that include atom transfer, abstraction and insertion.

Adenylate kinase (AK) mediates the reversible transfer of phosphate groups between the adenylate nucleotides and contributes to the maintenance of their constant cellular level, necessary for energy metabolism and nucleic acid synthesis. The AK were purified from crude extracts of two sulfate-reducing bacteria (SRB), Desulfovibrio (D.) gigas NCIB 9332 and Desulfovibrio desulfuricans ATCC 27774, and biochemically and spectroscopically characterised in the native and fully cobalt- or zinc-substituted forms. These are the first reported adenylate kinases that bind either zinc or cobalt and are related to the subgroup of metal-containing AK found, in most cases, in Gram-positive bacteria. The electronic absorption spectrum is consistent with tetrahedral coordinated cobalt, predominantly via sulfur ligands, and is supported by EPR. The involvement of three cysteines in cobalt or zinc coordination was confirmed by chemical methods. Extended X-ray absorption fine structure (EXAFS) indicate that cobalt or zinc are bound by three cysteine residues and one histidine in the metal-binding site of the ``LID{''} domain. The sequence (129)Cys-X(5)-His-X(15)-Cys-X(2)-Cys of the AK from D. gigas is involved in metal coordination and represents a new type of binding motif that differs from other known zinc-binding sites of AK. Cobalt and zinc play a structural role in stabilizing the LID domain. (C) 2008 Elsevier Inc. All rights reserved.

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This work reports for the first time a resonance Raman study of the mixed-valence and fully reduced forms of Paracoccus pantotrophus bacterial cytochrome c peroxidase. The spectra of the active mixed-valence enzyme show changes in the structure of the ferric peroxidatic heme compared to the fully oxidized enzyme; these differences are observed upon reduction of the electron-transferring heme and upon full occupancy of the calcium site. For the mixed-valence form in the absence of Ca2+, the peroxidatic heme is six-coordinate and low-spin on the basis of the frequencies of the structure-sensitive Raman lines: the enzyme is inactive. With added Ca2+, the peroxidatic heme is five-coordinate high-spin and active. The calcium-dependent spectral differences indicate little change in the conformation of the ferrous electron-transferring heme, but substantial changes in the conformation of the ferric peroxidatic heme. Structural changes associated with Ca2+ binding are indicated by spectral differences in the structure-sensitive marker lines, the out-of-plane low-frequency macrocyclic modes, and the vibrations associated with the heme substituents of that heme. The Ca2+-dependent appearance of a strong gamma(15) saddling-symmetry mode for the mixed-valence form is consistent with a strong saddling deformation in the active peroxidatic heme, a feature seen in the Raman spectra of other peroxidases. For the fully reduced form in the presence of Ca2+, the resonance Raman spectra show that the peroxidatic heme remains high-spin.