Synthesis, structure and magnetic characterisation of a new layered ammonium manganese(II) diphosphate hydrate, (NH4)(2)[Mn-3(P2O7)(2)(H2O)(2)]

A new layered ammonium manganese(II) diphosphate, (NH4)(2)[Mn-3(P2O7)(2)(H2O)(2)], has been synthesised under solvothermal conditions at 433 K in ethylene glycol and the structure determined at 293 K using single-crystal X-ray diffraction data (M-r = 584.82, monoclinic, space group P2(1)/a, a = 9.4610( 8), b = 8.3565( 7), c = 9.477(1) Angstrom, beta = 99.908(9) degrees, V = 738.07 Angstrom(3), Z = 2, R = 0.0351 and R-w = 0.0411 for 1262 observed data (I > 3(sigma(I))). The structure consists of chains of cis- and trans-edge sharing MnO6 octahedra linked via P2O7 units to form layers of formula [Mn3P4O14(H2O)(2)](2-) in the ab plane. Ammonium ions lie between the manganese-diphosphate layers. A network of interlayer and ammonium-layer based hydrogen bonding holds the structure together. Magnetic measurements indicate Curie - Weiss behaviour above 30 K with mu(eff) = 5.74(1) mu(B) and theta = -23(1) K, consistent with the presence of high-spin Mn2+ ions and antiferromagnetic interactions. However, the magnetic data reveal a spontaneous magnetisation at 5 K, indicating a canting of Mn2+ moments in the antiferromagnetic ground state. On heating (NH4)(2)[Mn-3(P2O7)(2)(H2O)(2)] in water at 433 K under hydrothermal conditions, Mn-5(HPO4)(2)(PO4)(2).4H(2)O, synthetic hureaulite, is formed.

The interplay between geometry, electronic structure, and reactivity of Cu-Ni bimetallic (111) surfaces

The mutual influence of surface geometry (e.g. lattice parameters, morphology) and electronic structure is discussed for Cu-Ni bimetallic (111) surfaces. It is found that on flat surfaces the electronic d-states of the adlayer experience very little influence from the substrate electronic structure which is due to their large separation in binding energies and the close match of Cu and Ni lattice constants. Using carbon monoxide and benzene as probe molecules, it is found that in most cases the reactivity of Cu or Ni adlayers is very similar to the corresponding (111) single crystal surfaces. Exceptions are the adsorption of CO on submonolayers of Cu on Ni(111) and the dissociation of benzene on Ni/Cu(111) which is very different from Ni(111). These differences are related to geometric factors influencing the adsorption on these surfaces.

Cobalt(III) complexes of some aromatic thiohydrazides – Synthesis, characterization and structure

Co(NH3)(5)Cl]Cl-2 forms neutral 1:3 complex by reaction with aromatic thiohydrazides, i.e. thiobenzhydrazide, o-hydroxythiobenzhydrazide, thiophen-2-thiohydrazide and furan-2-thiohydrazide. All these complexes are diamagnetic and have been characterized by elemental analysis and combination of spectroscopic methods. Cyclic voltammometry of the complexes shows irreversible metal centered and ligand centered electron transfer reactions. One complex, tris-o-hydroxythiobenzhydrazidocobalt(III),has been crystallized from DMSO solution to produce solvated crystals and its structure has been established by X-ray crystallography. Cobalt(III) ion is linked through three hydrazinic nitrogen and three sulfur atoms of three identical deprotonated ligand molecules in a distorted octahedral environment. Involvement of -OH group in intramolecular and intermolecular hydrogen bonding is crucial for crystal formation.

Evaluating the structure and magnitude of the ash plume during the initial phase of the 2010 Eyjafjallajökull eruption using lidar observations and NAME simulations

The Eyjafjallajökull volcano in Iceland erupted explosively on 14 April 2010, emitting a plume of ash into the atmosphere. The ash was transported from Iceland toward Europe where mostly cloud-free skies allowed ground-based lidars at Chilbolton in England and Leipzig in Germany to estimate the mass concentration in the ash cloud as it passed overhead. The UK Met Office's Numerical Atmospheric-dispersion Modeling Environment (NAME) has been used to simulate the evolution of the ash cloud from the Eyjafjallajökull volcano during the initial phase of the ash emissions, 14–16 April 2010. NAME captures the timing and sloped structure of the ash layer observed over Leipzig, close to the central axis of the ash cloud. Relatively small errors in the ash cloud position, probably caused by the cumulative effect of errors in the driving meteorology en route, result in a timing error at distances far from the central axis of the ash cloud. Taking the timing error into account, NAME is able to capture the sloped ash layer over the UK. Comparison of the lidar observations and NAME simulations has allowed an estimation of the plume height time series to be made. It is necessary to include in the model input the large variations in plume height in order to accurately predict the ash cloud structure at long range. Quantitative comparison with the mass concentrations at Leipzig and Chilbolton suggest that around 3% of the total emitted mass is transported as far as these sites by small (<100 μm diameter) ash particles.

Determination by MAD-DM of the structure of the DNA duplex d[ACGTACG(5-BrU)]2 at 1.46 Å and 100 K

A four-wavelength MAD experiment on a new brominated octanucleotide is reported here. d[ACGTACG(5-BrU)], C77H81BrN30O32P7, (DNA) = 2235, tetragonal, P43212 (No. 96), a = 43.597, c = 26.268 Å, V = 49927.5 Å3, Z = 8, T = 100 K, R = 10.91% for 4312 reflections between 15.0 and 1.46 Å resolution. The self-complementary brominated octanucleotide d[ACGTACG(5-BrU)]2 has been crystallized and data measured to 1.45 Å at both 293 K and a second crystal flash frozen at 100 K. The latter data collection was carried out to the same resolution at the four wavelengths 0.9344, 0.9216, 0.9208 and 0.9003 Å, around the Br K edge at 0.92 Å and the structure determined from a map derived from a MAD data analysis using pseudo-MIR methodology, as implemented in the program MLPHARE. This is one of the first successful MAD phasing experiments carried out at Sincrotrone Elettra in Trieste, Italy. The structure was refined using the data measured at 0.9003 Å, anisotropic temperature factors and the restrained least-squares refinement implemented in the program SHELX96, and the helical parameters are compared with those previously determined for the isomorphous d(ACGTACGT)2 analogue. The asymmetric unit consists of a single strand of octamer with 96 water molecules. No countercations were located. The A-DNA helix geometry obtained has been analysed using the CURVES program.

Structure and spectra of dichloro(hydroxy-methoxy-di(2-pyridyl)methane)copper(II)

The non-electrolyte dichloro(hydroxy-methoxy-di(2-pyridylmethane)copper(II), resulting from the reaction of di(2-pyridyl)ketone and copper(II) chloride in methanol solution, was isolated and characterized and its structure was determined by X-ray diffraction. The pyridyl nitrogens and the chloride anions virtually from a basal plane in which lies the copper atom, while the oxygen of the methoxy group is in an apical position at a distance of 2.497 (3)Å. The nitrogenous base adopts the boat conformation with the pyridyl rings forming a dihedral angle of 108.72 (14)°. The nearest interatomic copper distance of 3.940(3)Å precludes copper-copper interactions, while the proximity of copper to the out-of-plane chlorine atoms [3.109(3)Å] suggests weakly bound chloro-bridged dimers. Spectral changes indicate that protic molecules displace the methoxy group and water affords the corresponding 1,1-diol.

The vertical cloud structure of the West African monsoon: a 4 year climatology using CloudSat and CALIPSO

The West African summer monsoon (WAM) is an important driver of the global climate and locally provides most of the annual rainfall. A solid climatological knowledge of the complex vertical cloud structure is invaluable to forecasters and modelers to improve the understanding of the WAM. In this paper, 4 years of data from the CloudSat profiling radar and CALIPSO are used to create a composite zonal mean vertical cloud and precipitation structure for the WAM. For the first time, the near-coincident vertical radar and lidar profiles allow for the identification of individual cloud types from optically thin cirrus and shallow cumulus to congestus and deep convection. A clear diurnal signal in zonal mean cloud structure is observed for the WAM, with deep convective activity enhanced at night producing extensive anvil and cirrus, while daytime observations show more shallow cloud and congestus. A layer of altocumulus is frequently observed over the Sahara at night and day, extending southward to the coastline, and the majority of this cloud is shown to contain supercooled liquid in the top. The occurrence of deep convective systems and congestus in relation to the position of the African easterly jet is studied, but only the daytime cumulonimbus distribution indicates some influence of the jet position.

Three dimensional picture of the local structure of 1,4-Polybutadiene from a complete atomistic model and neutron scattering data

An efficient method of combining neutron diffraction data over an extended Q range with detailed atomistic models is presented. A quantitative and qualitative mapping of the organization of the chain conformation in both glass and liquid phase has been performed. The proposed structural refinement method is based on the exploitation of the intrachain features of the diffraction pattern by the use of internal coordinates for bond lengths, valence angles and torsion rotations. Models are built stochastically by assignment of these internal coordinates from probability distributions with limited variable parameters. Variation of these parameters is used in the construction of models that minimize the differences between the observed and calculated structure factors. A series of neutron scattering data of 1,4-polybutadiene at the region 20320 K is presented. Analysis of the experimental data yield bond lengths for C-C and C=C of 1.54 and 1.35 Å respectively. Valence angles of the backbone were found to be at 112 and 122.8 for the CCC and CC=C respectively. Three torsion angles corresponding to the double bond and the adjacent R and β bonds were found to occupy cis and trans, s(, trans and g( and trans states, respectively. We compare our results with theoretical predictions, computer simulations, RIS models, and previously reported experimental results.

Structure property relationships in electrically conducting copolymers formed from pyrrole and N-methyl pyrrole

A series of copolymers containing differing proportions of pyrrole and N-methyl pyrrole were prepared electrochemically at various temperatures using acetonitrile as the solvent. The resultant electrical conductivity decreases universally with increasing fraction of N-methyl pyrrole. Films prepared with p-toluene sulfonate as the dopant show a marked variation in structural anisotropy as revealed by X-ray scattering with apparent copolymer content. There is a clear trend between the variation in electrical conductivity and this structural anisotropy. Different patterns of behaviour are observed for films prepared using perchlorate as the dopant and this is attributed to the role of the dopant and final structure in determining the relative reactivities of the pyrrole and N-methyl pyrrole monomers. These observations support the concept that the introduction of methyl substituents into a polypyrrole chain results in a twisted chain conformation. The structure and properties of the resultant copolymer films are particularly sensitive to the preparation conditions.

Synthesis, chemical, electrochemical characterization of oxomolybdenum(V) complexes of 2-(3,5-dimethyl pyrazol-1-yl) benzothiazole ligand: crystal structure of ligand and oxomolybdenum(VI) complex and density functional theory (DFT) calculation

This work reports the ligational behavior of the neutral bidentate chelating molecule 2-(3,5-dimethyl pyrazol-1-yl) benzothiazole towards the oxomolybdenum(V) center. Both mononuclear complexes of the type (MoOX3L)-O-V and binuclear complexes of the formula (Mo2O4X2L2)-O-V (where X = Cl, Br) are isolated in the solid state. The complexes are characterized by elemental analyses, various spectroscopic techniques (UV-Vis IR), magnetic susceptibility measurement at room temperature, and cyclic voltammetry for their redox behavior at a platinum electrode in CH3CN. The mononuclear complexes (MoOX3L)-O-V are found to be paramagnetic while the binuclear complexes Mo2O4X2L2 are diamagnetic. Crystal and molecular structure of the ligand and the dioxomolybdenum complex (MoO2Br2L)-O-VI (obtained from the complex MoOBr3L during crystallization) have been solved by single crystal X-ray diffraction technique. Relevant DFT calculations of the ligand and the complex (MoO2Br2L)-O-VI are also carried out.

Business level strategy and performance: the moderating effects of environment and structure

Purpose – This study aims to examine the moderating effects of external environment and organisational structure in the relationship between business-level strategy and organisational performance. Design/methodology/approach – The focus of the study is on manufacturing firms in the UK belonging to the electrical and mechanical engineering sectors, and respondents were CEOs. Both objective and subjective measures were used to assess performance. Non-response bias was assessed statistically and appropriate measures taken to minimise the impact of common method variance (CMV). Findings – The results indicate that environmental dynamism and hostility act as moderators in the relationship between business-level strategy and relative competitive performance. In low-hostility environments a cost-leadership strategy and in high-hostility environments a differentiation strategy lead to better performance compared with competitors. In highly dynamic environments a cost-leadership strategy and in low dynamism environments a differentiation strategy are more helpful in improving financial performance. Organisational structure moderates the relationship of both the strategic types with ROS. However, in the case of ROA, the moderating effect of structure was found only in its relationship with cost-leadership strategy. A mechanistic structure is helpful in improving the financial performance of organisations adopting either a cost-leadership or a differentiation strategy. Originality/value – Unlike many other empirical studies, the study makes an important contribution to the literature by examining the moderating effects of both environment and structure on the relationship between business-level strategy and performance in a detailed manner, using moderated regression analysis.

On the structure and dynamics of Indian monsoon depressions

ERA-Interim reanalysis data from the past 35 years have been used with a newly-developed feature tracking algorithm to identify Indian monsoon depressions originating in or near the Bay of Bengal. These were then rotated, centralised and combined to give a fully three-dimensional 106-depression composite structure – a considerably larger sample than any previous detailed study on monsoon depressions and their structure. Many known features of depression structure are confirmed, particularly the existence of a maximum to the southwest of the centre in rainfall and other fields, and a westward axial tilt in others. Additionally, the depressions are found to have significant asymmetry due to the presence of the Himalayas; a bimodal mid-tropospheric potential vorticity core; a separation into thermally cold- (~–1.5K) and neutral- (~0K) cores near the surface with distinct properties; and that the centre has very large CAPE and very small CIN. Variability as a function of background state has also been explored, with land/coast/sea, diurnal, ENSO, active/break and Indian Ocean Dipole contrasts considered. Depressions are found to be markedly stronger during the active phase of the monsoon, as well as during La Niña. Depressions on land are shown to be more intense and more tightly constrained to the central axis. A detailed schematic diagram of a vertical cross-section through a composite depression is also presented, showing its inherent asymmetric structure.

Dynamic auroral structure in the vicinity of the polar cusp - multipoint observations during southward and northward IMF

The low- and high-latitude boundary layers of the earth's magnetosphere [low-latitude boundary layer (LLBL) and mantle] play important roles in transferring momentum and energy from the solar wind to the magnetosphere-ionosphere system. Particle precipitation, field-aligned current, auroral emission, ionospheric ion drift and ground magnetic perturbations are among the low-altitude parameters that show signatures of various plasma processes in the LLBL and the magnetopause current layer. Magnetic merging events, Kelvin-Helmholtz waves, and pressure pulses excited by the variable solar wind/magnetosheath plasma are examples of boundary phenomena that may be coupled to the ionosphere via field-aligned currents. Optical auroral observation, by photometry and all-sky TV cameras, is a unique technique for investigating the spatial and temporal structure of the electron precipitation associated with such phenomena. However, the distinction between the different boundary layer plasma populations cannot in general be unambiguously determined by optics alone. Additional information, such as satellite observations of particle boundaries and field-aligned currents, is needed in order to identify the plasma source(s) and the magnetosphere-ionosphere coupling mode(s). Two categories of auroral activity/structure in the vicinity of the polar cusp are discussed in this paper, based on combined ground and satellite data. In one case, the quasi-periodic sequence of auroral events at the polar cap boundary involves accelerated electrons (< 1 keV) moving poleward (< 1 km s-1) and azimuthally along the persistent cusp/cleft arc poleward boundary with velocities (< 4 km s-1), comparable to the local ionospheric ion drift during periods of southward IMF. A critical question is whether or not the optical events signify a corresponding plasma flow across the open/closed field line boundary in such cases. Near-simultaneous observations of magnetopause flux transfer events (FTEs) and such optical/ion drift events are reported. The reverse pattern of motion of discrete auroral forms is observed during positive interplanetary magnetic field (IMF) B(Z), i.e. equatorward motion into the cusp/cleft background arc from the poleward edge. Combined satellite and ground-based information for the latter cases indicate a source mechanism, poleward of the cusp at the high-latitude magnetopause or plasma mantle, giving rise to strong momentum transfer and electron precipitation structures within a approximately 200 km-wide latitudinal zone at the cusp/cleft poleward boundary. The striking similarities of auroral electrodynamics in the cleft/mantle region during northward and southward IMF indicate that a qualitatively similar solar wind-magnetosphere coupling mode is operating. It is suggested that, in both cases, the discrete auroral forms represent temporal/spatial structure of larger-scale convection over the polar magnetosphere.

Analysis and manipulation of the structure of odor plumes from a piezo-electric release system and measurements of upwind flight of male Almond Moths, Cadra cautella, to pheromone plumes

We investigated the plume structure of a piezo-electric sprayer system, set up to release ethanol in a wind tunnel, using a fast response mini-photoionizaton detector. We recorded the plume structure of four different piezo-sprayer configurations: the sprayer alone; with a 1.6-mm steel mesh shield; with a 3.2-mm steel mesh shield; and with a 5 cm circular upwind baffle. We measured a 12 × 12-mm core at the center of the plume, and both a horizontal and vertical cross-section of the plume, all at 100-, 200-, and 400-mm downwind of the odor source. Significant differences in plume structure were found among all configurations in terms of conditional relative mean concentration, intermittency, ratio of peak concentration to conditional mean concentration, and cross-sectional area of the plume. We then measured the flight responses of the almond moth, Cadra cautella, to odor plumes generated with the sprayer alone, and with the upwind baffle piezo-sprayer configuration, releasing a 13:1 ratio of (9Z,12E)-tetradecadienyl acetate and (Z)-9-tetradecenyl acetate diluted in ethanol at release rates of 1, 10, 100, and 1,000 pg/min. For each configuration, differences in pheromone release rate resulted in significant differences in the proportions of moths performing oriented flight and landing behaviors. Additionally, there were apparent differences in the moths’ behaviors between the two sprayer configurations, although this requires confirmation with further experiments. This study provides evidence that both pheromone concentration and plume structure affect moth orientation behavior and demonstrates that care is needed when setting up experiments that use a piezo-electric release system to ensure the optimal conditions for behavioral observations.

How to be a fig wasp down under: the diversity and structure of an Australian fig wasp community

Endophytic insects and their parasitoids provide valuable models for community ecology. The wasp communities in inflorescences of fig trees have great potential for comparative studies, but we must first describe individual communities. Here, we add to the few detailed studies of such communities by describing the one associated with Ficus rubiginosa in Australia. First, we describe community composition, using two different sampling procedures. Overall, we identified 14 species of non-pollinating fig wasp (NPFW) that fall into two size classes. Small wasps, including pollinators, gallers and their parasitoids, were more abundant than large wasps (both galler and parasitoid species). We show that in figs where wasps emerge naturally, the presence of large wasps may partly explain the low emergence of small wasps. During fig development, large gallers oviposit first, before and around the time of pollination, while parasitoids lay eggs after pollination. We further show that parasitoids in the subfamily Sycoryctinae, which comprise the majority of all individual NPFWs, segregate temporally by laying eggs at different stages of fig development. We discuss our results in terms of species co-existence and community structure and compare our findings to those from fig wasp communities on other continents.