scholarly journals A new approach for structure analysis of two-dimensional membrane protein crystals using X-ray powder diffraction data

2011 ◽  
Vol 20 (2) ◽  
pp. 457-464 ◽  
Author(s):  
R. A. Dilanian ◽  
C. Darmanin ◽  
J. N. Varghese ◽  
S. W. Wilkins ◽  
T. Oka ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Structure Analysis ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Protein Crystals ◽  
Two Dimensional ◽  
Powder Diffraction Data ◽  
New Approach ◽  
X Ray

scholarly journals Structure analysis of two-dimensional membrane proteins using X-ray powder diffraction data

2011 ◽  
Vol 67 (a1) ◽  
pp. C591-C592
Author(s):  
R. A. Dilanian ◽  
C. Darmanin ◽  
J. N. Varghese ◽  
S. W. Wilkins ◽  
T. Oka ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Structure Analysis ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Two Dimensional ◽  
Powder Diffraction Data ◽  
X Ray

Using phases retrieved from two-dimensional projections to facilitate structure solution from X-ray powder diffraction data

2011 ◽  
Vol 44 (5) ◽  
pp. 1023-1032 ◽  
Author(s):  
Dan Xie ◽  
Christian Baerlocher ◽  
Lynne B. McCusker
Keyword(s):  
Electron Microscopy ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Two Dimensional ◽  
Powder Diffraction Data ◽  
Phase Information ◽  
Powder Charge ◽  
X Ray ◽  
Structure Solution ◽  
Using Data

A single-crystal charge-flipping algorithm has been applied to two-dimensional projections derived from X-ray powder diffraction data to retrieve structure-factor phases. These phases proved to be as reliable as those obtained from high-resolution transmission electron microscopy (HRTEM) images or from precession electron diffraction data. In particular, the stronger reflections tend to be correctly phased. The two-dimensional electron-density `images' obtained in this way show the same features as the corresponding HRTEM images, but with higher resolution. Application of the powder charge-flipping algorithm to the full three-dimensional powder diffraction data in conjunction with phases derived from several such (arbitrarily selected) projections was found to have a significant and beneficial effect on the structure solution. The approach was first developed using data collected on the complex zeolite TNU-9, and was then tested further using data for IM-5 and SSZ-74, two similarly complex zeolites. All three of these structures were originally solved by combining X-ray powder diffraction and electron microscopy data, because X-ray diffraction data alone were not sufficient. In all three cases, the phase information derived from two-dimensional subsets of the X-ray powder diffraction data resulted in a significant improvement in the electron-density maps generated by the powder charge-flipping algorithm. The inclusion of this phase information allowed all three structures to be determined from the X-ray data alone. This two-dimensional X-ray powder diffraction approach appears to offer a remarkably simple and powerful method for solving the structures of complex polycrystalline materials.

Structure of a new compound KBaB5O9 and photoluminescence characteristics of KBaB5O9:Eu3+

2007 ◽  
Vol 22 (4) ◽  
pp. 292-294 ◽  
Author(s):  
Y. P. Sun ◽  
Yinxiao Du ◽  
W. Y. Wang ◽  
Ming He ◽  
G. M. Cai ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Two Dimensional ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
Monoclinic System ◽  
X Ray ◽  
Cell Parameters ◽  
Dimensional Network

Crystal structure of a new compound KBaB5O9 has been investigated from X-ray powder diffraction data. This compound is isostructural with KSrB5O9 and crystallizes in the monoclinic system with space group P21/c. Unit-cell parameters are a=6.7200(2) Å, b=8.3256(2) Å, c=14.3674(4) Å, and β=92.6103(3) deg. Its structure contains both B3O7 and B3O8 rings, which share a common B atom to form a complex two dimensional network constituting the basic B5O9 unit in the formula. Adjacent networks are bound together by Ba and K atoms, which have eight- and nine-coordinate sites, respectively. In addition, DTA and TGA curves reveal that KBaB5O9 decomposes at 798 °C. Photoluminescence (PL) characteristics of KBaB5O9:Eu3+ have been studied. The PL spectra show the strongest emission at 618 nm and the quench concentration of Eu3+ is 4 at. %.

Equatorial aberration for powder diffraction data collected by continuous-scan integration of a silicon strip X-ray detector

2021 ◽  
Vol 36 (3) ◽  
pp. 169-175
Author(s):  
Takashi Ida
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Peak Shift ◽  
Two Dimensional ◽  
Peak Shape ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
Third Order ◽  
X Ray

The application of continuous-scan integration to collect X-ray diffraction data with a Si strip X-ray detector (CSI-SSXD) introduces additional effects on the peak shift and deformation of peak shape caused by the equatorial aberration. A deconvolutional method to correct the effects of equatorial aberration in CSI-SSXD data is proposed in this study. There are four critical angles related to the effects of spillover of the incident X-ray beam from the specimen face in the CSI-SSXD data. Exact values of cumulants of the equatorial aberration function are efficiently evaluated by 4 × 4 point two-dimensional Gauss–Legendre integral. A naïve two-step deconvolutional method has been applied to remove the effects of the first and third-order cumulants of the equatorial aberration function from the observed CSI-SSXD data. The performance of the algorithm has been tested by analyses of CSI-SSXD data of three LaB6 powder specimens with the widths of 20, 10, and 5 mm, collected with a diffractometer with the goniometer radius of 150 mm.

2,4,6-Triisopropylbenzenesulfonamide: Monte Carlo structure solution from X-ray powder diffraction data for a molecular system containing four independent asymmetric rotors

1999 ◽  
Vol 55 (6) ◽  
pp. 1068-1074 ◽  
Author(s):  
Maryjane Tremayne ◽  
Elizabeth J. MacLean ◽  
Chiu C. Tang ◽  
Christopher Glidewell
Keyword(s):  
Monte Carlo ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Molecular System ◽  
Two Dimensional ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Profile Fitting ◽  
Structure Solution ◽  
Full Profile

The crystal structure of 2,4,6-triisopropylbenzenesulfonamide, C15H25NO2S, has been solved from X-ray powder diffraction data collected at 120 (1) K using synchrotron radiation and refined by Rietveld methods. The structure was solved by the application of a Monte Carlo method in which trial structures were generated by random movement of the molecule in the unit cell and assessed using a full-profile-fitting technique. Intramolecular flexibility was introduced into the structure solution in the form of four independent asymmetric rotors, allowing the isopropyl and sulfonamide groups to rotate freely within the molecule. The structure is monoclinic P21/c, a = 16.9600 (6), b = 8.1382 (2), c = 11.7810 (2) Å, β = 104.777 (2)° with Z = 4. The molecules are linked by N—H...O hydrogen bonds, with N...O distances of 2.77 (1) and 2.92 (1) Å, into two-dimensional sheets built from R^2_2(8) and R^6_6(20) rings.

X-ray powder diffraction characterization of disilver trihydrogen paraperiodate

2006 ◽  
Vol 21 (1) ◽  
pp. 52-55
Author(s):  
Norberto Masciocchi ◽  
Davide Gianni
Keyword(s):  
Hydrogen Bonds ◽  
Rietveld Refinement ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Two Dimensional ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Cell Parameters ◽  
Full Profile

X-ray powder diffraction data for the trigonal form of disilver trihydrogen paraperiodate, Ag2H3IO6, are reported. The cell parameters are a=5.941 89(3), c=12.7253(1) Å, V=389.089(6) Å3, and ρ=5.65 g cm−3 for Z=3. A full-profile Rietveld refinement confirms the monophasic nature of the sample and the presence of two-dimensional corrugated layers of the A2BO6 type linked by hydrogen bonds. Short unsupported Ag–Ag contacts (about 3.02 Å) of the argentophilic type are also shown.

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