Complexity Of Agreement Research Articles

Identification of oxidized platinum single atoms on chlorinated γ–alumina support by density functional theory calculations and X-ray absorption spectroscopy

The existence and nature of oxidized Pt single atoms (SA) are unraveled on two γ-Al2O3 supported Pt catalysts (0.3 wt%) containing two chlorine contents (0.1 and 1.4 wt%) characterized by HR-HAADF-STEM and HERFD-XANES/EXAFS after a calcination treatment at 520 °C. Pt SA are revealed as PtOxCly complexes where the number of oxygen (x) and chlorine (y) ligands directly depends on the chlorine content. In order to interpret these experimental observations and provide coherent atomic structures for these PtOxCly complexes, the thermodynamic stability of the oxidized Pt SA species supported on the (100) surface model of γ-Al2O3 is determined by density functional theory (DFT) calculations as a function of the calcination conditions determined by the temperature, and partial pressures of H2O, HCl and O2. It is shown that various ligands such as Cl, OH, O (from the alumina surface or as extra-ligands) and H2O are coordinated to Pt depending on the conditions and chlorine content. Various square planar and square-based pyramidal PtOxCly species such as PtO2, PtOCl2, PtCl4 are found to be stable in calcination conditions, while octahedral Pt(OH)xCl4-x(H2O) are stabilized in XAS recording conditions. The features of these DFT simulated octahedral Pt SA species are successfully compared to XAS data. On one hand, based on thermodynamics arguments, we proposed models of supported complexes in agreement with EXAFS coordination numbers and distances (Pt-O, Pt-Cl and Pt-Al). On the other hand, the simulated XANES spectra at the Pt L3-edge for these complexes match well with the experimental HERFD-XANES and reveal that the bump feature observed between 11575 eV and 11585 eV (post-edge signal) is a tracer of the amount of Cl coordinated to Pt SA.

Photoluminescence of Ni(II), Pd(II), and Pt(II) Complexes [M(Me2dpb)Cl] Obtained from C‒H Activation of 1,5-Di(2-pyridyl)-2,4-dimethylbenzene (Me2dpbH).

The three complexes [M(Me2dpb)Cl] (M = Ni, Pd, Pt) containing the tridentate N,C,N-cyclometalating 3,5-dimethyl-1,5-dipyridyl-phenide ligand (Me2dpb−) were synthesised using a base-assisted C‒H activation method. Oxidation potentials from cyclic voltammetry increased along the series Pt < Ni < Pd from 0.15 to 0.74 V. DFT calculations confirmed the essentially ligand-centred π*-type character of the lowest unoccupied molecular orbital (LUMO) for all three complexes in agreement with the invariant reduction processes. For the highest occupied molecular orbitals (HOMO), contributions from metal dyz, phenyl C4, C2, C1, and C6, and Cl pz orbitals were found. As expected, the dz2 (HOMO-1 for Ni) is stabilised for the Pd and Pt derivatives, while the antibonding dx2−y2 orbital is de-stabilised for Pt and Pd compared with Ni. The long-wavelength UV-vis absorption band energies increase along the series Ni < Pt < Pd. The lowest-energy TD-DFT-calculated state for the Ni complex has a pronounced dz2-type contribution to the overall metal-to-ligand charge transfer (MLCT) character. For Pt and Pd, the dz2 orbital is energetically not available and a strongly mixed Cl-to-π*/phenyl-to-π*/M(dyz)-to-π* (XLCT/ILCT/MLCT) character is found. The complex [Pd(Me2dpb)Cl] showed a structured emission band in a frozen glassy matrix at 77 K, peaking at 468 nm with a quantum yield of almost unity as observed for the previously reported Pt derivative. No emission was observed from the Ni complex at 77 or 298 K. The TD-DFT-calculated states using the TPSSh functional were in excellent agreement with the observed absorption energies and also clearly assessed the nature of the so-called “dark”, i.e., d‒d*, excited configurations to lie low for the Ni complex (≥3.18 eV), promoting rapid radiationless relaxation. For the Pd(II) and Pt(II) derivatives, the “dark” states are markedly higher in energy with ≥4.41 eV (Pd) and ≥4.86 eV (Pt), which is in perfect agreement with the similar photophysical behaviour of the two complexes at low temperatures.

Joint bodies in the European Union's international agreements: Delegating powers to the European Commission in EU external relations

In many international agreements, the European Union sets up joint bodies such as ‘association councils’ or ‘joint committees’. These institutions bring together European Union and third-country officials for agreement implementation. To date, we know surprisingly little about how much discretion the European Commission enjoys in them. Drawing on a principal–agent framework, we hypothesise that the complexity of agreements, the voting rule, conflict within the Council, and agency losses can explain Commission discretion in these institutions. Drawing on an original dataset covering nearly 300 such joint bodies set up by the European Union since 1992, we find robust empirical support for all expectations except for the agency loss thesis. Our findings suggest that the European Commission is the primary actor in the implementation of many of the European Union's international agreements, allowing it to influence EU external relations beyond what is currently acknowledged in the literature.

Development of a Macrophage-Based ADCC Assay.

Fc-dependent effector functions are an important determinant of the in vivo potency of therapeutic antibodies. Effector function is determined by the combination of FcRs bound by the antibody and the cell expressing the relevant FcRs, leading to antibody-dependent cellular cytotoxicity (ADCC). A number of ADCC assays have been developed; however, they suffer from limitations in terms of throughput, reproducibility, and in vivo relevance. Existing assays measure NK cell-mediated ADCC activity; however, studies suggest that macrophages mediate the effector function of many antibodies in vivo. Here, we report the development of a macrophage-based ADCC assay that relies on luciferase expression in target cells as a measure of live cell number. In the presence of primary mouse macrophages and specific antibodies, loss of luciferase signal serves as a surrogate for ADCC-dependent killing. We show that the assay functions for a variety of mouse and human isotypes with a model antigen/antibody complex in agreement with the known effector function of the isotypes. We also use this assay to measure the activity of a number of influenza-specific antibodies and show that the assay correlates well with the known in vivo effector functions of these antibodies.

Transboundary Water Conflicts as Postcolonial Legacy (the Case of Nile Basin)

It is not shortage or lack of water that leads to conflict but the way how water is governed and managed. It is said that water will be, much more than oil, the major geopolitical issue of the 21st century. Although it is difficult to demonstrate this, it is clear that the increasing scarcity of the resource, on the one hand, and the configuration of its availability, on the other, are conflict-generating. In the particular case of the African continent, the large catchment basins of the Nile, Niger and Chad, shared by many states of unequal power, are the scene of inefficient hydro-diplomacy. Indeed, north to south, the Nile Delta is 161 km long and covers the coastline of Egypt from Alexandria in the west to Port Said in the east. Egypt with 100 mln population is de facto the principal hydro-hegemon state in the Nile basin. Nevertheless, a couple of riparian states, as Ethiopia (105 mln population), have taken measures in order to challenge this status quo: the signature and launching of the Nile Basin Initiative (NBI), the signature of Cooperative Framework Agreement (CFA), the construction of the Grand Ethiopian Renaissance Dam (GERD) and the signing of the Declaration of Principles Agreement. The article attempts to analyse the urgency of the problem of water resources allocation in Africa with particular focus to the Nile basin and the complexity of agreements regulating the issue dating back to the colonial era. The study also emphasizes the difficulties bilateral and multilateral aids faced while trying to solve a conflict. As Nile for many states is not just a source of water, it is the host of a fragile ecosystem, essential for maintaining the environmental and ecological balance of North-East Africa.

Exploring the Specificity of Rationally Designed Peptides Reconstituted from the Cell-Free Extract of Deinococcus radiodurans toward Mn(II) and Cu(II).

A series of five rationally designed decapeptides [DEHGTAVMLK (DP1), THMVLAKGED (DP2), GTAVMLKDEH (Term-DEH), TMVLDEHAKG (Mid-DEH), and DEHGGGGDEH (Bis-DEH)] have been studied for their interactions with Cu(II) and Mn(II) ions. The peptides, constructed including the most prevalent amino acid content found in the cell-free extract of Deinococcus radiodurans (DR), play a fundamental role in the antioxidant mechanism related to its exceptional radioresistance. Mn(II) ions, in complex with these peptides, are found to be an essential ingredient for the DR protection kit. In this work, a detailed characterization of Cu(II) systems was included, because Cu(II)–peptide complexes have also shown remarkable antioxidant properties. All peptides studied contain in their sequence coordinating residues that can bind effectively Mn(II) or Cu(II) ions with high affinity, such as Asp, Glu, and His. Using potentiometric techniques, NMR, EPR, UV–vis, and CD spectroscopies, ESI-MS spectrometry, and molecular model calculations, we explored the binding properties and coordination modes of all peptides toward the two metal ions, were able to make a metal affinity comparison for each metal system, and built a structural molecular model for the most stable Cu(II) and Mn(II) complexes in agreement with experimental evidence.

Chemical-Shift Perturbations Reflect Bile Acid Binding to Norovirus Coat Protein: Recognition Comes in Different Flavors.

Bile acids have been reported as important cofactors promoting human and murine norovirus (NoV) infections in cell culture. The underlying mechanisms are not resolved. Through the use of chemical shift perturbation (CSP) NMR experiments, we identified a low‐affinity bile acid binding site of a human GII.4 NoV strain. Long‐timescale MD simulations reveal the formation of a ligand‐accessible binding pocket of flexible shape, allowing the formation of stable viral coat protein–bile acid complexes in agreement with experimental CSP data. CSP NMR experiments also show that this mode of bile acid binding has a minor influence on the binding of histo‐blood group antigens and vice versa. STD NMR experiments probing the binding of bile acids to virus‐like particles of seven different strains suggest that low‐affinity bile acid binding is a common feature of human NoV and should therefore be important for understanding the role of bile acids as cofactors in NoV infection.

Cryptic molecular diversity in the morphologically variable rotiferan Brachionus quadridentatus (Rotifera: Monogononta)

Brachionus quadridentatus is a morphologically variable species distributed worldwide. Its taxonomy is confusing due the numerous infrasubspecific variants described in the taxon. Here we explore genetic diversity of certain B. quadridentatus populations, using sequences of COI mtDNA and 18S rDNA genes. With traditional morphology (taxonomic keys), the specimens identified fell into three recognized variants: B. quadridentatus quadridentatus, B. quadridentatus f. brevispinus and B. quadridentatus f. cluniorbicularis. The coalescent species delimitation analysis highly supports the presence of at least three putative species within B. quadridentatus complex in agreement with the phylogenetic result and GMYC analysis with the 18S gene. Nevertheless, the morphological and mitochondrial information show that the variation within each of the three putative species is much more extensive, finding seven monophyletic and highly divergent genetic groups (&gt;10%) that have congruence with the morphotypes found in this study and ABGD analysis, which display clear morphological differences mainly in the diagnostic characters.

On the structure of superbasic (MgO)n sites solvated in a faujasite zeolite.

We report the synthesis and characterisation of a HY/MgO zeolite/oxide nanocomposite material with high crystallinity and highly dispersed, highly basic MgO sites. Preparation was optimized in order to preserve sample crystallinity, to avoid the formation of mesoporosity and to minimize the formation of separate Mg-containing phases. These features were checked by means of electron microscopy, X-ray powder diffraction, porosimetry and IR spectroscopy. A highly dispersed material was obtained, comprising nanoclusters of magnesium oxide and hydroxide hosted by the microporous zeolite framework. The location and structure of the Mg-containing clusters have been studied by means of a combination of Rietveld refinement of XRPD data and high quality quantum mechanical simulations. The refinement has shown the presence of magnesium and oxygen atoms in the double six-membered ring cages, consistent with the presence of mononuclear Mg moieties. However, the composition and IR spectroscopy demonstrate that other Mg species must exist, likely located in the zeolite pores. In order to propose candidate structures for these species, several hypothetic periodic models of the material were built by placing (MgO)n clusters in different locations of the zeolite structure, taking into account the material composition and other constraints imposed by the experimental observations. Periodic structures with P1 symmetry were optimized at the B3LYP-D*/DZVP level with the CRYSTAL code and classified according to their stability. Two families of possible sites were identified: highly solvated (MgO)n units in narrow cavities and less coordinated clusters in the supercages. The stability of these clusters appears to be regulated by the ability of Mg2+ and O2- ions to interact with the pore walls and by the formation of Mg-OH species as result of the reaction of Mg-O couples with remaining acidic protons. The reactivity of four representative models with CO2 has been simulated at the B3LYP-D*/TZVP level. CO2 forms very stable linear end-on adducts with low coordinated Mg ions in most cases. Isolated sites give rise to bridge bidentate complexes in agreement with previous spectroscopic observations. The formation of hydrogen-carbonates is observed only on specific sites, through a process having a low adsorption energy because of the high deformation of the adsorption site.

Gender as a complex feature

Grammatical gender is a feature that adds complexity to the languages in which it occurs. It is a structural ‘extra’ whose reasons for existence can be questioned on all levels: formal, semantic and functional. This article investigates the ways in which the complexity of individual gender systems can be assessed. It discusses three domains: complexity of values, complexity of assignment and complexity of agreement, as well as the methodological and empirical difficulties that arise in each domain. The paper closes with some thoughts on the relation between the three domains and on the question whether complex equals difficult.

Photoinduced linkage isomerization in new rhenium(I) tricarbonyl complexes coordinated to N-nitrite and O-nitrite

The ambidentate nitrite ion, NO2−, is a biologically relevant species that can be coordinated to transition metals via the nitrogen or oxygen atom. Most of its physiological effects involve metalloproteins so it is important to understand the factors that control the predominance of one or another isomer. In this work, we present the syntheses and characterization by spectroscopy, electrochemistry and DFT calculations of new rhenium(I) tricarbonyl complexes with different polypyridyl ligands in the coordination sphere and with the nitrite ion coordinated through either its N- or O-atom. For two of them we have determined their crystal structures by X-ray diffraction and we have found that in the solid when the ancilliary ligand is bpy the N-binding mode is the most stable, while dmb is the ligand, the –CH3 substituents imposed the C–H (methyl group)⋯O–NO (nitrito) interactions favoring the O-binding mode. However, at room temperature in CH2Cl2 the nitro isomer is the most stable for both complexes in agreement with DFT calculations. Both complexes exhibit photoinduced linkage isomerism which could be of interesting in the design of new materials. Although nitro complexes are precursors of nitrosyl compounds, in this work the synthesis of the nitrosyl complexes as solid could not be possible because there is higher π-backbonding from Re(I) to the carbonyl groups, or to the polypyridil ligands instead of to the NO group, which is π-acceptor, in consequence the nitrosyl complexes are unstable and decompose immediately to the solvate complexes.

Extreme Multidrug Resistant HIV-1 Protease with 20 Mutations Is Resistant to Novel Protease Inhibitors with P1′-Pyrrolidinone or P2-Tris-tetrahydrofuran

Extreme drug resistant mutant of HIV-1 protease (PR) bearing 20 mutations (PR20) has been studied with the clinical inhibitor amprenavir (1) and two potent antiviral investigational inhibitors GRL-02031 (2) and GRL-0519 (3). Clinical inhibitors are >1000-fold less active on PR20 than on wild-type enzyme, which is consistent with dissociation constants (KL) from isothermal titration calorimetry of 40 nM for 3, 178 nM for amprenavir, and 960 nM for 2. High resolution crystal structures of PR20-inhibitor complexes revealed altered interactions compared with the corresponding wild-type PR complexes in agreement with relative inhibition. Amprenavir lacks interactions due to PR20 mutations in the S2/S2' subsites relative to PR. Inhibitors 2 and 3 lose interactions with Arg8' in PR20 relative to the wild-type enzyme because Arg8' shifts to interact with mutated L10F side chain. Overall, inhibitor 3 compares favorably with darunavir in affinity for PR20 and shows promise for further development.

Complexation of N'-[1-(3-aminophenyl)ethylidine]isonicotinohydrazide with La3+, Pr3+, Nd3+, Sm3+, Eu3+ and Gd3+ ions and associated thermodynamics

A novel Schiff base N'-[1-(3-aminophenyl)ethylidine]isonicotinohydrazide was prepared and its complexation behavior towards some selected lanthanides had been studied employing pH-metric and calorimetric titration and spectral techniques. pH-metric studies were carried out for the trivalent La, Pr, Nd, Sm, Eu, and Gd complexes in 30% aqueous-dioxane medium at constant ionic strength of 0.05 mol/L NaClO4 and at different temperatures of 293, 303 and 313 K. The proton-ligand formation constants of the ligand indicated the presence of only one dissociable proton while the metal-ligand formation constants were compatible with the formation of 1:1 Ln(III) complexes. The stability of the complexes followed the order: La3+<Pr3+<Nd3+<Sm3+<Eu3+>Gd3+, showing a break at gadolinium. The thermodynamic parameters, ΔG, ΔH and ΔS associated with protonation and complexation reactions were negative which suggested that all reactions were exothermic and enthalpy-driven. Isothermal calorimetric studies of Gd3+-aeINH systems at 303 K also showed exothermic nature of the complexation reaction and formation of 1:1 complex in agreement with the pH-metric data. Formation of 1:1 complexes was confirmed by the characterization of Nd(III) complex. A seven coordinated geometry was assigned for the complex based on its elemental and spectral data.

Computational Evidence for the Catalytic Mechanism of Human Glutathione S-Transferase A3-3: A QM/MM Investigation

A Quantum Mechanics/Molecular Mechanics (QM/MM) computational investigation of the catalytic mechanism of the human glutathione transferase A3-3 (hGSTA3-3) has been carried out. The results demonstrate that the isomerization reaction is concerted, but highly asynchronous: in the first reaction phase the glutathione (GSH) negative sulfur (thiolate) acts as a base and deprotonates carbon C4 of the substrate Delta(5)-androstene-3,17-dione (Delta(5)-AD); in the second reaction phase the hydroxyl proton of the tyrosine fragment Y9 is AD). The initial state of the enzyme is subsequently restored by transferred to C6 affording the Delta(4)-androstene-3,17-dione product (Delta(4)-transferring a proton from the GSH sulfur to the tyrosine negative oxygen. There is no evidence for a genuine stepwise mechanism involving the formation of a real dienolate intermediate as suggested in previous papers. Furthermore, our computations have evidenced that, when we consider the whole process (including the restoring of the enzyme), GSH behaves as a base/acid catalyst (as hypothesized by some authors), but it requires the participation of the tyrosine Y9 acting as a proton shuttle. A fingerprint has been used to rank the electrostatic effects on the catalysis of the various residues surrounding the active site. This analysis highlights the role played by the arginine residue R15 in stabilizing the initial complex in agreement with previous suggestions based on-crystal structures.

Theoretical study of structural and optical properties of lithium cation complexes with dimethyl sulfoxide

DFT and ab initio MP2 studies of optimal geometries, energetics, electron structure and electron spectra of [Li(DMSO) n ] + complexes, n = 1–6, are presented. The coordination number increase causes Li–O bond elongation and decreasing electron density transfer from oxygen to lithium. This is connected with the exponential decrease of the complex formation energy per DMSO ligand, weakens the Li–O bonds and lowers the DMSO structure deformation. The highest stability of [Li(DMSO) 4] + complexes in agreement with experimental data can be explained in the terms of the population analysis based on the topological analysis of electron density. TD-DFT calculations of vertical electronic transitions for IEFPCM polarizable continuum model in DMSO solutions and molecular orbital analysis indicate that the Li–DMSO bonding is responsible for the blue shift of the original DMSO excitation energy. These type complexes are important for the drug-transport through the cell membranes in biological systems.

Dimensions of Decision Making: Determining the Complexity of Politics on the High Court of Australia

While we know a great deal about the ideological divides that explain the behavior of U.S. Supreme Court Justices, we know very little about their counterparts in other countries. The liberal-conservative dimension captures a great deal of the variance around the behavior of justices on the Supreme Court, but little is known about the generalizability of this one-dimensional explanation to other national high courts. This paper attempts to determine the nature and complexity of agreement and disagreement among Justices on the High Court of Australia. Using data from High Court decisions from 1985-2000, I employ a multidimensional scaling technique to determine the number of cross-cutting issues dividing Justices in ideological space. I conclude that, unlike the U.S. Supreme Court, at least two dimensions are needed to accurately describe decision-making on the High Court.

Heliobacterial Rieske/cytb complex

Data on structure and function of the Rieske/cytb complex from Heliobacteria are scarce. They indicate that the complex is related to the b (6) f complex in agreement with the phylogenetic position of the organism. It is composed of a diheme cytochrome c, and a Rieske iron-sulfur protein, together with transmembrane cytochrome b (6) and subunit IV. Additional small subunits may be part of the complex. The cofactor content comprises heme c (i), first discovered in the Q(i) binding pocket of b (6) f complexes. The redox midpoint potentials are more negative than in b (6) f complex in agreement with the lower redox midpoint potentials (by about 150 mV) of its reaction partners, menaquinone, and cytochrome c (553). The enzyme is implicated in cyclic electron transfer around the RCI. Functional studies are favored by the absence of antennae and the simple photosynthetic reaction chain but are hampered by the high oxygen sensitivity of the organism, its chlorophyll, and lipids.

Density functional based treatment of endohedrally hydrogen-doped fullerene, nH2@C60

The possibility of the formation of endohedral complexes between H2 molecules and C60 fullerene is discussed on the basis of general geometric considerations as well as the results of density functional based tight binding (DFTB) calculations. The obtained results reveal that only one hydrogen molecule being incorporated inside the C60 cage can form the stable complex in agreement with geometric considerations and recent experimental data. It is also shown that for large numbers of encapsulated hydrogen molecules, some of them become chemisorbed on the inner surface of the cage. We show that for the capsule side wall eventually breaks and the mechanism of its breaking is studied by DFTB molecular dynamics simulations thus, this complex seems to be highly improbable.

The morphology proteins Mdm12/Mmm1 function in the major β-barrel assembly pathway of mitochondria

The beta-barrel proteins of mitochondria are synthesized on cytosolic ribosomes. The proteins are imported by the translocase of the outer membrane (TOM) and the sorting and assembly machinery (SAM). It has been assumed that the SAM(core) complex with the subunits Sam35, Sam37 and Sam50 represents the last import stage common to all beta-barrel proteins, followed by splitting in a Tom40-specific route and a route for other beta-barrel proteins. We have identified new components of the beta-barrel assembly machinery and show that the major beta-barrel pathway extends beyond SAM(core). Mdm12/Mmm1 function after SAM(core) yet before splitting of the major pathway. Mdm12/Mmm1 have been known for their role in maintenance of mitochondrial morphology but we reveal assembly of beta-barrel proteins as their primary function. Moreover, Mdm10, which functions in the Tom40-specific route, can associate with SAM(core) as well as Mdm12/Mmm1 to form distinct assembly complexes, indicating a dynamic exchange between the machineries governing mitochondrial beta-barrel assembly. We conclude that assembly of mitochondrial beta-barrel proteins represents a major function of the morphology proteins Mdm12/Mmm1.

Purification, crystallization and X-ray diffraction analyses of the T. elongatus PSII core dimer with strontium replacing calcium in the oxygen-evolving complex

The core complex of photosystem II (PSII) was purified from thermophillic cyanobaterium Thermosynechococcus elongatus grown in Sr 2+-containing and Ca 2+-free medium. Functional in vivo incorporation of Sr 2+ into the oxygen-evolving complex (OEC) was confirmed by EPR analysis of the isolated and highly purified SrPSII complex in agreement with the previous study of Boussac et al. [J. Biol. Chem. 279 (2004) 22809–22819]. Three-dimensional crystals of SrPSII complex were obtained which diffracted to 3.9 Å and belonged to the orthorhombic space group P2 12 12 1 with unit cell dimensions of a = 133.6 Å, b = 236.6 Å, c = 307.8 Å. Anomalous diffraction data collected at the Sr K-X-ray absorption edge identified a novel Sr 2+-binding site which, within the resolution of these data (6.5 Å), is consistent with the positioning of Ca 2+ in the recent crystallographic models of PSII [Ferreira et al. Science 303 (2004) 1831–1838, Loll et al. Nature 438 (2005) 1040–1044]. Fluorescence measurements on SrPSII crystals confirmed that crystallized SrPSII was active in transferring electrons from the OEC to the acceptor site of the reaction centre. However, SrPSII showed altered functional properties of its modified OEC in comparison with that of the CaPSII counterpart: slowdown of the Q A-to-Q B electron transfer and stabilized S 2Q A − charge recombination.