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  • 1
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 27 (1971), S. 2293-2298 
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Golgi mannosidase IA is a class I α-mannosidase which catalyzes the conversion of Man9GlcNAc2 or Man8GlcNAc2 oligosaccharide substrates to Man5GlcNAc2 during the maturation of Asn-linked oligosaccharides. The enzyme is a type II membrane protein, and a recombinant form of mannosidase IA from mouse, lacking the transmembrane domain, has been expressed in Pichia pastoris, purified to homogeneity and crystallized by the hanging-drop vapor-diffusion method. The crystals grow as thin rods, with unit-cell dimensions a = 54.9, b = 135.01, c = 69.9 Å. The crystals exhibit the symmetry of space group P2221 and diffract to 2.8 Å resolution. The asymmetric unit contains one monomer (∼53 kDa) and has a solvent content of 59%.
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 54 (1998), S. 163-171 
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Results of characterization of defects in natural diamond crystals by high-resolution X-ray diffractometry, absolute integrated intensity (ρ) measurements, topography and diffuse X-ray scattering (DXS) techniques are reported. The samples are 〈111〉 natural diamond platelets of dimensions 2̃ × 2 mm with thickness in the range 0̃.5–1 mm. A five-crystal X-ray diffractometer in three-crystal configuration as well as a four-crystal diffractometer were employed with Mo Kα1 as the exploring radiation. Infrared absorption measurements showed that the samples belong to type Ia variety and contained varying concentrations of A and B forms of nitrogen aggregates as well as platelets. There were large variations in the values of diffraction curve half-widths (18 to 550′′) and values of ρ (2.4 × 10−5–76 × 10−5 rad) for 111 reflection, showing a wide variation in crystalline perfection. Projection and composite stationary X-ray topographs recorded with different diffraction vectors showed the presence of defects like low-angle boundaries. From the analysis of the observed distribution of diffuse X-ray scattering (DXS), point defect clusters were characterized. The clusters were of interstitial as well as vacancy type. The sizes of the defect clusters (Rcl) were determined to be in the range 40 to 190 nm and the volumes of the defect clusters (Acl) were in the range 1̃ × 10−25–28 × 10−25 m3. The defect clusters with sizes reported here could be investigated as the measurements were made close to the reciprocal-lattice points. The platelet size was found to vary inversely with the total concentration of nitrogen.
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  • 4
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 30 (1974), S. 1380-1380 
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 33 (2000), S. 614-617 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Small-angle neutron scattering was used to study the interactions between AOT/water/decane microemulsions and poly(ethylene oxide)-polyisoprene-poly(ethylene oxide) triblocks. The interdroplet spacing seems to be independent of molecular weight and polymer concentration. Scattering experiments on the polyisoprene layer yield a high q exponent of −1.6 ± 0.1, indicating that the layer is swollen by decane.
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  • 7
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Point-defect aggregates in (111) dislocation-free silicon single crystals grown by the float-zone (FZ) method have been studied by diffuse X-ray scattering (DXS) and compared with those in the Czochralski-grown (CZ) crystals. A two-axis X-ray diffractometer was used. It employs three monochromators in (+, −, −) setting to obtain a highly collimated and monochromatic Mo Kα1 beam. DXS measurements were made around the 111 reciprocal-lattice point (r.l.p.) with K* along ±[111] and ±[01{\bar 1}]; K is the vector which joins the elemental volume of the reciprocal space under investigation to the nearest r.l.p. For FZ crystals for a given K* the DXS intensity was higher for θ 〈 θB in comparison with that for θ 〉 θB showing that the anisotropy (DXS Iθ 〉 θB − DXS Iθ 〈 θB) is negative, as expected for vacancy clusters. For CZ crystals the anisotropy was positive, owing to the presence of interstitial clusters. The magnitude of anisotropy in the FZ crystals was smaller than that observed in the CZ crystals. The DXS intensity varies approximately as K−2 near Bragg peaks (Huang scattering) and as K*−4 (Stokes–Wilson scattering) away from it. From the K* values where the changeover from Huang to Stokes–Wilson scattering takes place the size of the clusters assumed to be the origin of the observed DXS is estimated as ̃2 × 10−4 and 2.6 × 10−3 mm for FZ and ̃5.5 × 10−4 and 3 × 10−3 mm for CZ crystals. The experimental data were compared with theoretically calculated DXS distributions assuming the defects to be dislocation loops. The number of point defects in a loop has been estimated.
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 57 (2001), S. 1282-1284 
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The asymmetric unit of the title compound, [Pt(C25H22P2)(C27H26P2)]Br2 or [Pt(dppm)(dppp)]Br2, where dppm is bis(diphenylphosphino)methane and dppp is 1,3-bis(diphenylphosphino)propane, consists of a discrete [Pt(dppm)(dppp)]2+ cation and two Br− anions at van der Waals distances. This is the first reported platinum(II) complex containing both dppm and dppp ligands. Noticeable features are that the coordination of platinum by the differing dppm and dppp ligands produces a distorted coordination geometry with differing ligand bite angles (and to a lesser extent bond distances), and that the strain induced by the formation of the four-membered dppm chelate ring has a marked effect upon the bond angles at the P atoms of this ligand.
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  • 9
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: High-resolution X-ray diffractometry, absolute integrated intensity (ρ) measurements, diffuse X-ray scattering (DXS) and infrared (IR) absorption techniques were used to investigate the influence of oxygen on the structural perfection of high purity (resistivity of the order of 4 kΩ cm) float zone (FZ) grown (111) silicon single crystals. A multicrystal diffractometer set in (+,-,-,+) geometry, with Mo Kα1 radiation, was employed. From the infrared measurements, the oxygen concentration in the sample was determined to be 1.3 × 1017 atoms cm^{-3}. High-resolution X-ray diffraction curves of the as-grown crystal had half-widths of ∼11 arcsec; the ρ value was 3.5 × 10^{-5} rad. To incorporate oxygen in a controlled manner into the specimens, they were annealed under dry oxygen ambient for 8 h in the temperature range 573–1373 K (in eight steps). Up to 723 K there was no appreciable change in oxygen content or in the degree of perfection. Annealing at temperatures (AT) 〉 873 K resulted in considerable increases in the oxygen content, as well as significant improvements in the degree of perfection. For example, as the level of oxygen increased from 1.3 × 1017 to 3.6 × 1017 atoms cm^{-3} for A_T=873 K, the values of half-widths and ρ decreased to ∼7 arcsec and 2.4 × 10^{-5} rad, respectively. However, annealing above 1273 K produced deterioration in lattice perfection. DXS measurements showed remarkable changes in the nature of point defects and their clusters with change in AT. Up to A_T=973 K, the defects were predominantly vacancy clusters. However, with AT in the range 1073–1273 K, the predominent defects were isolated interstitials. Further increase in AT led to interstitial cluster formation, which deteriorated the lattice perfection. This study clearly demonstrates that oxygen concentration in the range ∼3 × 1017 to 13 × 1017 atoms cm^{-3} leads to significant improvement in structural perfection of silicon single crystals.
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  • 10
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Bending of 25 mm-diameter (100) silicon wafers produced by 100 nm-thick cosputtered molybdenum–silicon films has been investigated just after deposition, after rapid thermal annealing and after etching of the deposits. Values of biaxial stress in the films were determined by the use of a widely used relation. The Mo:Si ratio in the as-deposited films was 89:11. Radii of curvature of substrates were measured by a double-crystal X-ray diffractometer. Blank wafers with three widely different radii of curvature (33, 62 and 250 m) were chosen as specimens and their curvatures were taken into account in the determination of the value of biaxial stress in wafers with deposits. All the wafers were convex when viewed from the polished surface side on which the films were deposited. Values of σ for wafers with as-deposited films were in the range 3 × 108 to 14 × 108 Nm−2 (tensile). Wafers with higher initial bending showed higher values of stress. Deposition led to degradation of perfection, as revealed by broadening of the diffraction curves and the contrast in the topographs. Rapid thermal annealing at 1273 and 1373 K (3–4 min) led to formation of the MoSi2 phase and to a notable relaxation of stress. The values of σ were in the range 1 × 107 to 6̃ × 108 N m−2 (tensile). The value of the stress was lowest for the blank wafer with smallest bending. Annealing also improved the degree of crystalline perfection of the silicon. Experiments performed after etching of the annealed specimens showed no significant change in the radii of curvature.
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