Structure of catalase determined by MicroED.

MicroED is a recently developed method that uses electron diffraction for structure determination from very small three-dimensional crystals of biological material. Previously we used a series of still diffraction patterns to determine the structure of lysozyme at 2.9 Å resolution with MicroED (Shi et al., 2013). Here we present the structure of bovine liver catalase determined from a single crystal at 3.2 Å resolution by MicroED. The data were collected by continuous rotation of the sample under constant exposure and were processed and refined using standard programs for X-ray crystallography. The ability of MicroED to determine the structure of bovine liver catalase, a protein that has long resisted atomic analysis by traditional electron crystallography, demonstrates the potential of this method for structure determination

Simultaneous Dempster-Shafer clustering and gradual determination of number of clusters using a neural network structure

In this paper we extend an earlier result within Dempster-Shafer theory ["Fast Dempster-Shafer Clustering Using a Neural Network Structure," in Proc. Seventh Int. Conf. Information Processing and Management of Uncertainty in Knowledge-Based Systems (IPMU'98)] where several pieces of evidence were clustered into a fixed number of clusters using a neural structure. This was done by minimizing a metaconflict function. We now develop a method for simultaneous clustering and determination of number of clusters during iteration in the neural structure. We let the output signals of neurons represent the degree to which a pieces of evidence belong to a corresponding cluster. From these we derive a probability distribution regarding the number of clusters, which gradually during the iteration is transformed into a determination of number of clusters. This gradual determination is fed back into the neural structure at each iteration to influence the clustering process.Comment: 6 pages, 10 figure

Theory for structure and bulk-modulus determination

A new method for direct evaluation of both crystalline structure, bulk modulus B_0, and bulk-modulus pressure derivative B'_0 of solid materials with complex crystal structures is presented. The explicit and exact results presented here permit a multidimensional polynomial fit of the total energy as a function of all relevant structure parameters to simultaneously determine the equilibrium configuration and the elastic properties. The method allows for inclusion of general (internal) structure parameters, e.g., bond lengths and angles within the unit cell, on an equal footing with the unit-cell lattice parameters. The method is illustrated by the calculation of B_0 and B'_0 for a few selected materials with multiple structure parameters for which data is obtained by using first-principles density functional theory.Comment: 7 pages, 2 figures, submitted to Phys. Rev.

Structure determination of the reconstructed Au(110) surface

The LEED pattern of the Au(110) surface shows a (1 × 2) and also a (1× 3) superstructure. The (1 × 2) superstructure has been determined by comparison of LEED intensities with model calculations. The missing row model is the most probable model. A minimum of the averaged r-factor, , has been found for 15% contraction of the first layer spacing without atomic displacements in the second layer

Isolation and Structure Determination of Antioxidants Active Compounds From Ethyl Acetate Extract of Heartwood Namnam (Cynometra Cauliflora L.)

Active compounds with antioxidant activity were isolated from ethyl acetate extract of namnam stem (C. cauliflora L.) that had undergone maceration and fractionation by gravity column chromatography. The compounds were later identified by by using UV-Vis Spectrophotometry, FTIR, LCMS and 1H-NMR. Ethyl acetate extract of namnam stem showed considerably high antioxidant activity (IC50 value 4.68 ± 0.035 ppm). The results of analysis by UV-Vis and FTIR showed carbonyl group conjugated with an aromatic ring at band I (?max 330.22 nm), chromophore group of alkene (C=C) at band II (?max 268.67 nm) and functional groups such as O?H (3343.91 cm-1), C=O (1729.23 cm-1), C=C (1652.64 and 1611.99 cm-1), C?O (1269.89) and C?H ortho (738.23 cm-1). LCMS (m/z 270.9246) and 1H-NMR data showed seven proton signals on the aromatic ring at carbon position C-3 at ?H 6.86 ppm (1H, s), C-6 at ?H 5.95 ppm (1H, d, J=1.95 Hz), C-8 at ?H 6.25 ppm (1H, d, J= 1.95 Hz), C-2' and C-6' at ?H 7.03 ppm (2H, d, J=7.87 Hz), C-3' and C-5' at ?H 6.87 ppm (2H, d, J= 7.87 Hz) so that the structure was identified as a flavonoid which was 4 ', 5,7-trihydroxy-flavones or known as apigenin. The isolated apigenin had very strong antioxidant activity, as shown by IC50 value of 5.18 ± 0.014 pp

Co-Determination in Germany: 1949-1979 and There Beyond: Bonding or Compulsion?

Co-determination refers to a set of rules and institutions which form an interlocking system and as such provide the unique structure of German corporate governance. This essay deals with the reasons responsible for bringing the structure about. In particular, the decision making process leading up to co-determination is carefully analyzed in terms of deciding the question, whether the participants were engaged in rent-seeking or in efficient legislation. Key words: co-determination, decisions under uncertainty, strategic legislative choice, human capital accumulation, joint stock companies, demountation, performance of institutionsindustrial organization ;

Spectroscopy of Superfluid Pairing in Atomic Fermi Gases

We study the dynamic structure factor for density and spin within the crossover from BCS superfluidity of atomic fermions to the Bose-Einstein condensation of molecules. Both structure factors are experimentally accessible via Bragg spectroscopy, and allow for the identification of the pairing mechanism: the spin structure factor allows for the determination of the two particle gap, while the collective sound mode in the density structure reveals the superfluid state.Comment: 4 pages, 3 figure

Quantitative adsorbate structure determination under catalytic reaction conditions

Current methods allow quantitative local structure determination of adsorbate geometries on surfaces in ultrahigh vacuum (UHV) but are incompatible with the higher pressures required for a steady-state catalytic reactions. Here we show that photoelectron diffraction can be used to determine the structure of the methoxy and formate reaction intermediates during the steady-state oxidation of methanol over Cu(110) by taking advantage of recent instrumental developments to allow near-ambient pressure x-ray photoelectron spectroscopy. The local methoxy site differs from that under static UHV conditions, attributed to the increased surface mobility and dynamic nature of the surface under reaction conditions

Structure determination from powder data : Mogul and CASTEP

When solving the crystal structure of complex molecules from powder data, accurately locating the global minimum can be challenging, particularly where the number of internal degrees of freedom is large. The program Mogul provides a convenient means to access typical torsion angle ranges for fragments related to the molecule of interest. The impact that the application of modal torsion angle constraints has on the structure determination process of two structure solution attempts using DASH is presented. Once solved, accurate refinement of a molecular structure against powder data can also present challenges. Geometry optimisation using density functional theory in CASTEP is shown to be an effective means to locate hydrogen atom positions reliably and return a more accurate description of molecular conformation and intermolecular interactions than global optimisation and Rietveld refinement alone