Structural Studies of the Qarakhanid Dirham Using X-Ray Diffraction and Neutron Tomography Methods

Author(s):  
B. A. Abdurakhimov ◽  
M. Yu. Tashmetov ◽  
B. A. Bakirov ◽  
B. S. Yuldashev ◽  
S. E. Kichanov ◽  
...  
Author(s):  
James A. Lake

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.


2006 ◽  
Vol 153 (11) ◽  
pp. A2152 ◽  
Author(s):  
Kyung Yoon Chung ◽  
Won-Sub Yoon ◽  
James McBreen ◽  
Xiao-Qing Yang ◽  
Si Hyoung Oh ◽  
...  

Biochemistry ◽  
1972 ◽  
Vol 11 (6) ◽  
pp. 945-949 ◽  
Author(s):  
R. P. Rand ◽  
S. SenGupta

Author(s):  
S. Huband ◽  
D. S. Keeble ◽  
N. Zhang ◽  
A. M. Glazer ◽  
A. Bartasyte ◽  
...  

Powders of lithium niobate-tantalate across the full compositional range have been made and crystals grown using a lithium vanadate flux growth technique. The Li-content of a lithium tantalate crystal has been determined using the zero-birefringence temperature and Curie measurements, confirming the Li content is between that of congruent and stoichiometric crystals. X-ray diffraction measurements show the Nb/Ta displacement and octahedral tilt both decrease as the Ta content is increased. This also results in a decrease in the lattice parameters from lithium niobate to lithium tantalate. Birefringence measurements on the crystals as a function of temperature have been used to determine the point that the crystals become zero-birefringent, and by comparison with the structural studies have confirmed that it is not related to a phase transition and the structures remain polar through the zero-birefringence points.


2021 ◽  
Vol 77 (3) ◽  
pp. 137-143
Author(s):  
Ismail Fidan ◽  
Emel Onal ◽  
Catherine Hirel

The syntheses of 4-[4-(4,4,5,5-tetramethyl-2-imidazoline-3-oxide-1-oxyl-2-yl)phenoxy]phthalonitrile (3, C21H19N4O3) and 4-[4-(4,4,5,5-tetramethyl-2-imidazoline-1-oxyl-2-yl)phenoxy]phthalonitrile (4) were carried out by microwave-assisted nucleophilic aromatic substitution of 4-nitrophthalonitrile (2) by the pre-formed 2-(4-hydroxyphenyl)-4,4,5,5-tetramethyl-2-imidazoline-3-oxide-1-oxyl (1). Compounds 3 and 4 were characterized unambiguously by a rich array of analyses, such as melting point, FT–IR, MALDI–TOF MS, elemental analysis, UV–Vis, CV, EPR, magnetic measurements and single-crystal X-ray diffraction. Structural studies demonstrate that the C—H...X and C—X...π (X = O and N) interactions in the radical nitronyl nitroxide groups play an important role in the assembly of the crystal structures. Moreover, cyclic voltammetry analyses show that the phthalonitrile substituent retains the redox properties of the Ullman radicals.


2018 ◽  
Vol 7 (3.11) ◽  
pp. 48
Author(s):  
Kevin Alvin Eswar ◽  
Mohd Husairi Fadzillah Suhaimi ◽  
Muliyadi Guliling ◽  
Zuraida Khusaimi ◽  
Mohamad Rusop ◽  
...  

ZnO Nanostructures have been successfully deposited on of Porous silicon (PSi) via wet colloid chemical approach. PSi was prepared by electrochemical etching method. ZnO/PSi thin films were annealed in different temperature in the range of 300 °C to 700 °C. Surface morphology studies were conducted using field emission scanning microscopy (FESEM). Flower-like structures of ZnO were clearly seen at annealing temperature of 500 °C. The X-ray diffraction spectra (XRD) have been used to investigate the structural properties. There are three dominant peaks referred to plane (100), (002) and (101) indicates that ZnO has a polycrystalline hexagonal wurtzite structures. Plane (002) shows the highest intensities at annealing temperature of 500 °C. Based on plane (002) analysis, the sizes were in range of 30.78 nm to 55.18. In addition, it was found that the texture coefficient of plane (002) is stable compared to plane (100) and (101). 


2008 ◽  
Vol 63 (12) ◽  
pp. 1402-1406
Author(s):  
Monika Simon ◽  
Carol Csunderlik ◽  
G. Jones

N-Alkyl-o-nitrophenylcarbamates as solids present two carbonyl stretching bands in the region 1700 - 1800 cm−1 but similar N-alkyl-p-nitrophenylcarbamates have only one such band in the IR spectrum. In solution both kinds of carbamate present one carbonyl stretching band, but for the former, the splittings occur when the carbamates crystallize. Four crystal structures were analyzed by X-ray diffraction. The two ortho derivatives have more than one molecule in the asymmetric unit, which is consistent with the IR observations.


2002 ◽  
Vol 66 (3) ◽  
pp. 460-485 ◽  
Author(s):  
M. Clelia Ganoza ◽  
Michael C. Kiel ◽  
Hiroyuki Aoki

SUMMARY Current X-ray diffraction and cryoelectron microscopic data of ribosomes of eubacteria have shed considerable light on the molecular mechanisms of translation. Structural studies of the protein factors that activate ribosomes also point to many common features in the primary sequence and tertiary structure of these proteins. The reconstitution of the complex apparatus of translation has also revealed new information important to the mechanisms. Surprisingly, the latter approach has uncovered a number of proteins whose sequence and/or structure and function are conserved in all cells, indicating that the mechanisms are indeed conserved. The possible mechanisms of a new initiation factor and two elongation factors are discussed in this context.


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