Internal structure in small Au crystals resolved by three-dimensional inversion of coherent x-ray diffraction

This work studies the inter-structure of a SAPO-34 particle by Bragg coherent X-ray diffraction imaging and serial-block-face scanning electron microscopy.

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Ribosome Structural Organization

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100051670 ◽

1974 ◽

Vol 32 ◽

pp. 332-333

Author(s):

James A. Lake

Keyword(s):

Ribosomal Proteins ◽

Structural Organization ◽

Three Dimensional ◽

Small Subunit ◽

Structural Studies ◽

X Ray Diffraction ◽

Specific Antibodies ◽

X Ray ◽

E Coli ◽

Complete Sequences

The understanding of ribosome structure has advanced considerably in the last several years. Biochemists have characterized the constituent proteins and rRNA's of ribosomes. Complete sequences have been determined for some ribosomal proteins and specific antibodies have been prepared against all E. coli small subunit proteins. In addition, a number of naturally occuring systems of three dimensional ribosome crystals which are suitable for structural studies have been observed in eukaryotes. Although the crystals are, in general, too small for X-ray diffraction, their size is ideal for electron microscopy.

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X-ray microtomography

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100107058 ◽

1988 ◽

Vol 46 ◽

pp. 998-999

Author(s):

H.W. Deckman ◽

B.F. Flannery ◽

J.H. Dunsmuir ◽

K.D' Amico

Keyword(s):

Computed Tomography ◽

Internal Structure ◽

Imaging Technique ◽

Three Dimensional ◽

Tissue Structure ◽

Individual Element ◽

X Ray ◽

Non Invasive ◽

Panoramic Imaging ◽

Three Dimensional Images

We have developed a new X-ray microscope which produces complete three dimensional images of samples. The microscope operates by performing X-ray tomography with unprecedented resolution. Tomography is a non-invasive imaging technique that creates maps of the internal structure of samples from measurement of the attenuation of penetrating radiation. As conventionally practiced in medical Computed Tomography (CT), radiologists produce maps of bone and tissue structure in several planar sections that reveal features with 1mm resolution and 1% contrast. Microtomography extends the capability of CT in several ways. First, the resolution which approaches one micron, is one thousand times higher than that of the medical CT. Second, our approach acquires and analyses the data in a panoramic imaging format that directly produces three-dimensional maps in a series of contiguous stacked planes. Typical maps available today consist of three hundred planar sections each containing 512x512 pixels. Finally, and perhaps of most import scientifically, microtomography using a synchrotron X-ray source, allows us to generate maps of individual element.

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An investigation of polyhedral deformation in two mixed-metal diarsenates: SrZnAs2O7and BaCuAs2O7

Acta Crystallographica Section C Structural Chemistry ◽

10.1107/s2053229615005616 ◽

2015 ◽

Vol 71 (4) ◽

pp. 330-337 ◽

Cited By ~ 2

Author(s):

Sabina Kovač ◽

Ljiljana Karanović ◽

Tamara Đorđević

Keyword(s):

Crystal Structure ◽

Single Crystal ◽

General Formula ◽

Three Dimensional ◽

X Ray Diffraction ◽

Hydrothermal Conditions ◽

X Ray ◽

Open Framework ◽

Geometrical Characteristics ◽

Barium Copper

Two isostructural diarsenates, SrZnAs2O7(strontium zinc diarsenate), (I), and BaCuAs2O7[barium copper(II) diarsenate], (II), have been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction. The three-dimensional open-framework crystal structure consists of corner-sharingM2O5(M2 = Zn or Cu) square pyramids and diarsenate (As2O7) groups. Each As2O7group shares its five corners with five differentM2O5square pyramids. The resulting framework delimits two types of tunnels aligned parallel to the [010] and [100] directions where the large divalent nine-coordinatedM1 (M1 = Sr or Ba) cations are located. The geometrical characteristics of theM1O9,M2O5and As2O7groups of known isostructural diarsenates, adopting the general formulaM1IIM2IIAs2O7(M1II= Sr, Ba, Pb;M2II= Mg, Co, Cu, Zn) and crystallizing in the space groupP21/n, are presented and discussed.

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A new model for packing of type-I collagen molecules in the native fibril

Bioscience Reports ◽

10.1007/bf01114803 ◽

1981 ◽

Vol 1 (10) ◽

pp. 801-810 ◽

Cited By ~ 49

Author(s):

Karl A. Piez ◽

Benes L. Trus

Keyword(s):

Type I Collagen ◽

Hexagonal Lattice ◽

Three Dimensional ◽

Equatorial Region ◽

Type I ◽

X Ray Diffraction ◽

X Ray ◽

Left Handed ◽

Crystal Model ◽

Collagen Molecules

A specific fibril model is presented consisting of bundles of five-stranded microfibrils, which are usually disordered (except axially) but under lateral compression become ordered. The features are as follows (where D = 234 residues or 67 nm): (1) D-staggered collagen molecules 4.5 D long in the helical microfibril have a left-handed supercoil with a pitch of 400–700 residues, but microfibrils need not have helical symmetry. (2) Straight-tilted 0.5-D overlap regions on a near-hexagonal lattice contribute the discrete x-ray diffraction reflections arising from lateral order, while the gap regions remain disordered. (3) The overlap regions are equivalent, but are crystallographically distinguished by systematic displacements from the near-hexagonal lattice. (4) The unit cell is the same as in a recently proposed three-dimensional crystal model, and calculated intensities in the equatorial region of the x-ray diffraction pattern agree with observed values.

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Acemetacin cocrystals and salts: structure solution from powder X-ray data and form selection of the piperazine salt

IUCrJ ◽

10.1107/s2052252514004229 ◽

2014 ◽

Vol 1 (2) ◽

pp. 136-150 ◽

Cited By ~ 37

Author(s):

Palash Sanphui ◽

Geetha Bolla ◽

Ashwini Nangia ◽

Vladimir Chernyshev

Keyword(s):

Hydrogen Bonds ◽

Dissolution Rate ◽

Aqueous Medium ◽

Acid Amide ◽

Three Dimensional ◽

X Ray Diffraction ◽

Reference Drug ◽

X Ray ◽

Time Period ◽

Solid Form

Acemetacin (ACM) is a non-steroidal anti-inflammatory drug (NSAID), which causes reduced gastric damage compared with indomethacin. However, acemetacin has a tendency to form a less soluble hydrate in the aqueous medium. We noted difficulties in the preparation of cocrystals and salts of acemetacin by mechanochemical methods, because this drug tends to form a hydrate during any kind of solution-based processing. With the objective to discover a solid form of acemetacin that is stable in the aqueous medium, binary adducts were prepared by the melt method to avoid hydration. The coformers/salt formers reported are pyridine carboxamides [nicotinamide (NAM), isonicotinamide (INA), and picolinamide (PAM)], caprolactam (CPR),p-aminobenzoic acid (PABA), and piperazine (PPZ). The structures of an ACM–INA cocrystal and a binary adduct ACM–PABA were solved using single-crystal X-ray diffraction. Other ACM cocrystals, ACM–PAM and ACM–CPR, and the piperazine salt ACM–PPZ were solved from high-resolution powder X-ray diffraction data. The ACM–INA cocrystal is sustained by the acid...pyridine heterosynthon and N—H...O catemer hydrogen bonds involving the amide group. The acid...amide heterosynthon is present in the ACM–PAM cocrystal, while ACM–CPR contains carboxamide dimers of caprolactam along with acid–carbonyl (ACM) hydrogen bonds. The cocrystals ACM–INA, ACM–PAM and ACM–CPR are three-dimensional isostructural. The carboxyl...carboxyl synthon in ACM–PABA posed difficulty in assigning the position of the H atom, which may indicate proton disorder. In terms of stability, the salts were found to be relatively stable in pH 7 buffer medium over 24 h, but the cocrystals dissociated to give ACM hydrate during the same time period. The ACM–PPZ salt and ACM–nicotinamide cocrystal dissolve five times faster than the stable hydrate form, whereas the ACM–PABA adduct has 2.5 times faster dissolution rate. The pharmaceutically acceptable piperazine salt of acemetacin exhibits superior stability, faster dissolution rate and is able to overcome the hydration tendency of the reference drug.

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2D X-ray diffraction and molecular modelling of the crystalline structure of polyesters under uniaxial stress

Polymers and Polymer Composites ◽

10.1177/0967391121998225 ◽

2021 ◽

pp. 096739112199822

Author(s):

Ahmed I Abou-Kandil ◽

Gerhard Goldbeck

Keyword(s):

Crystalline Structure ◽

Molecular Modelling ◽

Three Dimensional ◽

Uniaxial Stress ◽

X Ray Diffraction ◽

X Ray ◽

Wide Range ◽

Modelling Techniques ◽

Diffraction Patterns

Studying the crystalline structure of uniaxially and biaxially drawn polyesters is of great importance due to their wide range of applications. In this study, we shed some light on the behaviour of PET and PEN under uniaxial stress using experimental and molecular modelling techniques. Comparing experiment with modelling provides insights into polymer crystallisation with extended chains. Experimental x-ray diffraction patterns are reproduced by means of models of chains sliding along the c-axis leading to some loss of three-dimensional order, i.e. moving away from the condition of perfect register of the fully extended chains in triclinic crystals of both PET and PEN. This will help us understand the mechanism of polymer crystallisation under uniaxial stress and the appearance of mesophases in some cases as discussed herein.

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A New POM-Based Supramolecular Compound: Synthesis, Structure and Adsorptive Property of [Cu(phen)2]3[W6O19]

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.919-921.2013 ◽

2014 ◽

Vol 919-921 ◽

pp. 2013-2016 ◽

Cited By ~ 2

Author(s):

Ya Bing Liu ◽

Hong Jie Wang ◽

Hong Kai Zhao

Keyword(s):

Three Dimensional ◽

Building Blocks ◽

Monoclinic Space Group ◽

X Ray Diffraction ◽

Hybrid Compound ◽

Adsorptive Property ◽

X Ray ◽

Hydrogen Bonding Interactions ◽

Compound Synthesis ◽

Metal Organic

A POM - based organice - inorganic hybrid compound with the chemical formula of[Cu (phen)2]3[W6O19] (phen = 1,10-phenanthroline) (1) has been hydrothermally synthesized andstructurally characterized by the elemental analysis, and single crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic space groupC2/c witha=18.319(4) Å,b= 17.311(4) Å,c= 22.248(4) Å,β= 112.40(3) o,V= 6523(2) Å3,Z= 4, R1= 0.0448, andwR2=0.1218. Compound 1 consists of the [W6O19]3-building blocks and [Cu (phen)2]+metal organic cationic moieties, which are packed together via the extensive hydrogen-bonding interactions to form a three-dimensional supramolecular framework. The adsorption of methylene blue (MB) under UV irradiation with 1 as the heterogeneous adsorbent has been investigated, showing a good adsorptive property of 1 for MB degradation.

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