scholarly journals X-ray tomographic analysis of the initial structure of the royal chamber and the nest-founding behavior of the drywood termite Incisitermes minor

2014 ◽  
Vol 60 (6) ◽  
pp. 453-460 ◽  
Author(s):  
S. Khoirul Himmi ◽  
Tsuyoshi Yoshimura ◽  
Yoshiyuki Yanase ◽  
Masao Oya ◽  
Toshiyuki Torigoe ◽  
...  
Keyword(s):  
Initial Structure ◽  
X Ray ◽  
Incisitermes Minor ◽  
Nest Founding ◽  
Tomographic Analysis

Hidden superlattice in Tl2(SC6H4S) and Tl2(SeC6H4Se) solved from powder X-ray diffraction

2011 ◽  
Vol 67 (5) ◽  
pp. 409-415 ◽  
Author(s):  
Kevin H. Stone ◽  
Dayna L. Turner ◽  
Mayank Pratap Singh ◽  
Thomas P. Vaid ◽  
Peter W. Stephens
Keyword(s):  
Additional Data ◽  
Sulfur Compound ◽  
Closed Shell ◽  
Initial Structure ◽  
X Ray Diffraction ◽  
Rietveld Refinements ◽  
X Ray ◽  
Additional Data Collection ◽  
Superlattice Structures ◽  
Counting Statistics

The crystal structures of the isostructural title compounds poly[(μ-benzene-1,4-dithiolato)dithallium], Tl2(SC6H4S), and poly[(μ-benzene-1,4-diselenolato)dithallium], Tl2(SeC6H4Se), were solved by simulated annealing from high-resolution synchrotron X-ray powder diffraction. Rietveld refinements of an initial structure with one formula unit per triclinic cell gave satisfactory agreement with the data, but led to a structure with impossibly close non-bonded contacts. A disordered model was proposed to alleviate this problem, but an alternative supercell structure leads to slightly improved agreement with the data. The isostructural superlattice structures were confirmed for both compounds through additional data collection, with substantially better counting statistics, which revealed the presence of very weak superlattice peaks not previously seen. Overall, each structure contains Tl—S or Tl—Se two-dimensional networks, connected by phenylene bridges. The sulfur (or selenium) coordination sphere around each thallium is a highly distorted square pyramid or a `see-saw' shape, depending upon how many Tl—S or Tl—Se interactions are considered to be bonds. In addition, the two compounds contain pairs of TlI ions that interact through a closed-shell `thallophilic' interaction: in the sulfur compound there are two inequivalent pairs of Tl atoms with Tl—Tl distances of 3.49 and 3.58 Å, while in the selenium compound those Tl—Tl interactions are at 3.54 and 3.63 Å.

scholarly journals X-ray Micro-Tomography as a Method to Distinguish and Characterize Natural and Cultivated Pearls

2021 ◽  
Vol 6 (4) ◽  
pp. 51
Author(s):  
Luisa Vigorelli ◽  
Elisabetta Croce ◽  
Debora Angelici ◽  
Raffaella Navone ◽  
Sabrina Grassini ◽  
...  
Keyword(s):  
Diagnostic Techniques ◽  
X Ray ◽  
Non Invasive ◽  
Heritage Studies ◽  
Different Types ◽  
Micro Tomography ◽  
Invasive Techniques ◽  
Tomographic Analysis ◽  
Private Collections

Digital radiography and computed tomography are two fundamental diagnostic techniques in different fields of research, including cultural heritage studies and gemmology. The application of these physical methods of investigation has gained considerable importance as they are non-invasive techniques. The presented work has been mainly focused on micro-tomographic analysis. The project is concerned with the study of natural and cultivated pearls in order to develop an investigation methodology for the analysis, distinction and characterization of different types of pearls, some of them belonging to different precious jewels from private collections. The investigations, carried out on a total of 22 heterogeneous types of pearls, allowed us to establish their origin (natural or cultivated) or to confirm/deny if a hypothesis was already expressed, and as well to highlight the cultivation methodology used case by case. Furthermore, it was possible to ascertain how large and varied the market for cultured pearls is nowadays and how difficult is, in some particular cases, to ascertain their attribution to a certain origin.

Modification of the Crystallographic Structure of Olanzapine during Solvation by PALS and X-Ray Diffraction Methods

2012 ◽  
Vol 733 ◽  
pp. 92-95
Author(s):  
Maciej Tydda ◽  
Bożena Jasińska ◽  
Anna E. Kozioł ◽  
Irena Wawrzycka-Gorczyca
Keyword(s):  
Crystallographic Structure ◽  
Initial Structure ◽  
X Ray Diffraction ◽  
X Ray

Two selected solvents were incorporated into the olanzapine structure. Molecules located inside the voids in the structure caused the changing of the o-Ps lifetime and intensity. After removing the n-butanol●H2O molecules, the materials returned to its initial structure. Creating the complex with the methanol●H2O leads to the change of the crystallographic structure of the olanzapine.

Microstructural and X-ray tomographic analysis of damage in extruded aluminium weld seams

2014 ◽  
Vol 31 (1) ◽  
pp. 94-104 ◽  
Author(s):  
A. J. den Bakker ◽  
X. Wu ◽  
L. Katgerman ◽  
S. van der Zwaag
Keyword(s):  
X Ray ◽  
Tomographic Analysis ◽  
Weld Seams

scholarly journals 3D X-ray tomographic analysis reveals how coesite is preserved in Muong Nong-type tektites

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Matteo Masotta ◽  
Stefano Peres ◽  
Luigi Folco ◽  
Lucia Mancini ◽  
Pierre Rochette ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Silica Glass ◽  
Spectroscopic Data ◽  
Multiscale Analysis ◽  
Nucleation Site ◽  
Vesicle Size ◽  
X Ray ◽  
Froth Layer ◽  
Post Shock ◽  
Tomographic Analysis

AbstractMuong Nong-type (MN) tektites are a layered type of tektite associated to the Australasian strewn field, the youngest (790 kyr) and largest on Earth. In some MN tektites, coesite is observed in association with relict quartz and silica glass within inclusions surrounded by a froth layer. The formation of coesite-bearing frothy inclusions is here investigated through a 3D textural multiscale analysis of the vesicles contained in a MN tektite sample, combined with compositional and spectroscopic data. The vesicle size distribution testifies to a post-shock decompression that induced melting and extensive vesiculation in the tektite melt. Compared to free vesicles, nucleated homogeneously in the tektite melt, froth vesicles nucleated heterogeneously on relict quartz surfaces at the margins of coesite-bearing inclusions. The rapid detachment of the froth vesicles and prompt reactivation of the nucleation site favoured the packing of vesicles and the formation of the froth structure. Vesicle relaxation time scales suggest that the vesiculation process lasted few seconds. The formation of the froth layer was instrumental for the preservation of coesite, promoting quenching of the inclusion core through the subtraction of heat during froth expansion, thereby physically insulating the inclusion until the final quench of the tektite melt.

Site Occupancy of the B2 Phase in Ti-25Al-zMo Alloys

2013 ◽  
Vol 3 (2) ◽  
pp. 32-44
Author(s):  
A. K. Singh ◽  
M. Premkumar
Keyword(s):  
Site Occupancy ◽  
Lattice Parameter ◽  
Initial Structure ◽  
Occupancy Models ◽  
X Ray Diffraction ◽  
X Ray ◽  
Alloy Chemistry ◽  
Theoretical Investigations ◽  
B2 Phase ◽  
Mo Content

The structure of the B2 phase has been investigated in Ti-25Al-30Mo, Ti-25Al-35Mo and Ti-25Al-40Mo alloys using Rietveld refinement of X-ray diffraction data in homogenized condition. Different initial structure models have been used for the refinement based on the analyzed alloy chemistry. Site occupancy models for the general alloy compositions (xTi-yAl-zMo) wherein the Ti (x) is less than 50 atom % have been proposed. The site occupancy of the B2 phase has been calculated and compared with those of earlier experimental and theoretical investigations. The lattice parameter of the B2 phase decreases with increase in Mo content at constant Al.

scholarly journals Crystallization, neutron data collection, initial structure refinement and analysis of a xyloglucan heptamer bound to an engineered carbohydrate-binding module from xylanase

2015 ◽  
Vol 71 (8) ◽  
pp. 1072-1077 ◽  
Author(s):  
Mats Ohlin ◽  
Laura von Schantz ◽  
Tobias E. Schrader ◽  
Andreas Ostermann ◽  
Derek T. Logan ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Structure Refinement ◽  
Carbohydrate Binding ◽  
Initial Structure ◽  
Data Sets ◽  
Rhodothermus Marinus ◽  
Structural Determinants ◽  
X Ray ◽  
Carbohydrate Binding Modules ◽  
Hydrolyzing Enzymes

Carbohydrate-binding modules (CBMs) are discrete parts of carbohydrate-hydrolyzing enzymes that bind specific types of carbohydrates. Ultra high-resolution X-ray crystallographic studies of CBMs have helped to decipher the basis for specificity in carbohydrate–protein interactions. However, additional studies are needed to better understand which structural determinants confer which carbohydrate-binding properties. To address these issues, neutron crystallographic studies were initiated on one experimentally engineered CBM derived from a xylanase, X-2 L110F, a protein that is able to bind several different plant carbohydrates such as xylan, β-glucan and xyloglucan. This protein evolved from a CBM present in xylanase Xyn10A ofRhodothermus marinus. The protein was complexed with a branched xyloglucan heptasaccharide. Large single crystals of hydrogenous protein (∼1.6 mm3) were grown at room temperature and subjected to H/D exchange. Both neutron and X-ray diffraction data sets were collected to 1.6 Å resolution. Joint neutron and X-ray refinement usingphenix.refineshowed significant density for residues involved in carbohydrate binding and revealed the details of a hydrogen-bonded water network around the binding site. This is the first report of a neutron structure of a CBM and will add to the understanding of protein–carbohydrate binding interactions.

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