The influence of Ni 2+ and other ions on the trigonal structure of DNA

Biopolymers ◽  
2020 ◽  
Author(s):  
Francisco J. Acosta‐Reyes ◽  
Mireia Pagan ◽  
Elsa Fonfría‐Subirós ◽  
Núria Saperas ◽  
Juan A. Subirana ◽  
...  
Keyword(s):  
Trigonal Structure

scholarly journals Microstructure, XRD and Mössbauer spectroscopy study of Gd doped BiFeO3

2020 ◽  
Vol 14 (2) ◽  
pp. 134-140
Author(s):  
Jolanta Dzik ◽  
Tomasz Pikula ◽  
Diana Szalbot ◽  
Małgorzata Adamczyk-Habrajska ◽  
Beata Wodecka-Duś ◽  
...  
Keyword(s):  
Orthorhombic Phase ◽  
Solid State Reaction Method ◽  
Structure Characteristic ◽  
Spectroscopy Study ◽  
Composition And Structure ◽  
Trigonal Structure ◽  
Spin Cycloid ◽  
Trigonal Phase ◽  
Hyperfine Interaction Parameters

The results of fabrication process and characterization of Bi1-xGdxFeO3 (x = 0.05, 0.07, 0.10) ceramics are reported in the paper. The samples were prepared by standard solid state reaction method from the mixture of oxides: Bi2O3, Fe2O3 and Gd2O3. The influence of Gd substitution on the microstructure and density of Bi1-xGdxFeO3 was studied. Phase composition and structure of the obtained samples were investigated by Xray diffraction. It turns out that the Bi1-xGdxFeO3 solid solutions with x = 0.05 and 0.07 crystallize in trigonal structure characteristic of BiFeO3 compound. For the sample with x = 0.1, beside the major trigonal phase, 6% of orthorhombic phase typical for GdFeO3 was detected. Hyperfine interaction parameters were studied by M?ssbauer spectroscopy. M?ssbauer results proved that the spin cycloid characteristic of BiFeO3 compound gradually disappears when substituting Gd3+ ions at the Bi3+ sites.

Crystal structure of microwave dielectric ceramics Ba[(Mg1−xCdx)0.33Nb0.67]O3

2007 ◽  
Vol 22 (4) ◽  
pp. 295-299
Author(s):  
J. X. Deng ◽  
X. R. Xing ◽  
J. Chen ◽  
R. B. Yu ◽  
G. R. Liu ◽  
...  
Keyword(s):  
Synthesis Temperature ◽  
Partial Substitution ◽  
Quantitative Phase Analysis ◽  
X Ray Diffraction ◽  
Low Frequencies ◽  
X Ray ◽  
Microwave Dielectric ◽  
Trigonal Structure ◽  
Ordering Degree ◽  
Dielectric Ceramics

A series of complex perovskite solid solutions of Ba[(Mg1−xCdx)0.33Nb0.67]O3 have been synthesized by the columbite method. Detailed Rietveld refinement of their X-ray diffraction data show that Ba[(Mg1−xCdx)0.33Nb0.67]O3 has an order trigonal structure. The ordering degree as determined by the B-site occupancies increases with the partial substitution of Cd for Mg. However, a decrease in the ordering degree in the Ba(Cd0.33Nb0.67)O3 sample is observed, which can be attributed to a relatively lower synthesis temperature. All the impurity phases are successfully identified by X-ray quantitative phase analysis. Dielectrics properties at low frequencies for all the Ba[(Mg1−xCdx)0.33Nb0.67]O3 compounds have been measured successfully.

scholarly journals Allotropes of tellurium from first-principles crystal structure prediction calculations under pressure

RSC Advances ◽  
2018 ◽  
Vol 8 (69) ◽  
pp. 39650-39656 ◽  
Author(s):  
Yuan Liu ◽  
Shunbo Hu ◽  
Riccarda Caputo ◽  
Kaitong Sun ◽  
Yongchang Li ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phase Stability ◽  
First Principles ◽  
Structure Prediction ◽  
Crystal Structure Prediction ◽  
Transition Sequence ◽  
Trigonal Structure ◽  
Cubic Structure

Through first-principles simulations, we suggest the phase stability of the allotropic transition sequence of tellurium from the trigonal structure up to the cubic structure.

Rapid Synthesis of Li2O-(Nb/Ta)2O5-TiO2 Solid Solution Having Superstructure by Smart Processing Techniques

2018 ◽  
Vol 941 ◽  
pp. 2006-2010
Author(s):  
Hiromi Nakano
Keyword(s):  
Millimeter Wave ◽  
Pressure Control ◽  
Atomic Diffusion ◽  
Wave Radiation ◽  
Rapid Synthesis ◽  
High Oxygen Pressure ◽  
M Phase ◽  
Trigonal Structure ◽  
Periodical Structure ◽  
Processing Techniques

We successfully synthesized Li1+x-yM1-x-3yTix+4yO3 solid solutions (M = Nb or Ta, LMT, 0.07 ≤ x ≤ 0.33, 0 ≤ y ≤ 0.175) that have a superstructure. The materials formed a superstructure known as the M-phase, which is formed by the periodical insertion of an intergrowth layer in a matrix having a trigonal structure. The homogeneous and periodical structure of M-phase in LNT needed to sinter at 1393 K for 40 h-200 h using a conventional electric furnace. In order to form the homogeneous intergrowth layers rapidly, millimeter-wave or air-pressure control atmos furnaces were also used as smart processing techniques. We concluded that atomic diffusion was promoted in the useful reaction-fields: millimeter-wave radiation or high oxygen pressure.

Filling of Carbon Nanotubes with Selenium by Vapor Phase Process

2006 ◽  
Vol 6 (1) ◽  
pp. 82-86 ◽  
Author(s):  
Jérôme Chancolon ◽  
Françoise Archaimbault ◽  
Alain Pineau ◽  
Sylvie Bonnamy
Keyword(s):  
Carbon Nanotubes ◽  
Vapor Phase ◽  
Capillary Condensation ◽  
Phase Method ◽  
X Ray Diffraction ◽  
Filling Rate ◽  
X Ray ◽  
Full Control ◽  
Trigonal Structure ◽  
Phase Process

A vapor phase method was developed to fill different kinds of nanotubes (including multiwall and singlewall nanotubes), which inner diameters range from 200 down to 1.5 nm. Experiments were performed with selenium in a sealed reactor in order to control the selenium partial pressure. This process allows a full control of the nanotube filling (partial or complete), i.e., either a selective diameter filling or a full filling rate. The weight gain of all the samples was plotted for different reaction temperature as a function of selenium pressure. Experimental isotherms are characteristic of capillary condensation of selenium, which occurs at first in the smallest nanotube inner diameters. X-ray diffraction data show that selenium confined in nanotubes with diameters larger than 3 nm keeps its trigonal structure.

scholarly journals About the polymorphism of [Li(C4H8O)3]I: crystal structures of trigonal and tetragonal polymorphs

2014 ◽  
Vol 70 (12) ◽  
pp. 555-558
Author(s):  
Stefanie Gärtner ◽  
Tobias Gärtner ◽  
Ruth-Maria Gschwind ◽  
Nikolaus Korber
Keyword(s):  
Rotation Axis ◽  
Ion Pairs ◽  
Three Dimensional ◽  
Intermolecular Forces ◽  
Ion Pair ◽  
Lithium Cation ◽  
Tetrahedral Coordination ◽  
Space Group ◽  
Trigonal Structure ◽  
Van Der Waals Contacts

Two new trigonal and tetragonal polymorphs of the title compound, iodidotris(tetrahydrofuran-κO)lithium, are presented, which both include the isolated ion pair Li(THF)3+·I−. One Li—I ion contact and three tetrahydrofuran (THF) molecules complete the tetrahedral coordination of the lithium cation. The three-dimensional arrangement in the two polymorphs differs notably. In the trigonal structure, the ion pair is located on a threefold rotation axis of space groupP-3 and only one THF molecule is present in the asymmetric unit. In the crystal, strands of ion pairs parallel to [001] are observed with an eclipsed conformation of the THF molecules relative to the Li...I axis of two adjacent ion pairs. In contrast, the tetragonal polymorph shows a much larger unit cell in which all atoms are located on general positions of the space groupI41cd. The resulting three-dimensional arrangement shows helical chains of ion pairs parallel to [001]. Apart from van der Waals contacts, no remarkable intermolecular forces are present between the isolated ion pairs in both structures.

Structures of stable and metastable Ge2Sb2Te5, an intermetallic compound in GeTe–Sb2Te3 pseudobinary systems

2004 ◽  
Vol 60 (6) ◽  
pp. 685-691 ◽  
Author(s):  
Toshiyuki Matsunaga ◽  
Noboru Yamada ◽  
Yoshiki Kubota
Keyword(s):  
Equilibrium State ◽  
Thermal Equilibrium ◽  
Metastable Phase ◽  
Stable Phase ◽  
Thermal Equilibrium State ◽  
Close Packed Structure ◽  
Trigonal Structure ◽  
Pseudobinary Systems ◽  
Packed Structure ◽  
Optical Disks

The most widely used memory materials for rewritable phase-change optical disks are the GeTe–Sb2Te3 pseudobinary compounds. Among these compounds, Ge2Sb2Te5 crystallizes into a cubic close-packed structure with a six-layer period (metastable phase) in the non-thermal equilibrium state, and a trigonal structure with a nine-layer period (stable phase) in the thermal equilibrium state. The structure of the stable phase has Ge/Sb layers in which Ge and Sb are randomly occupied, as does the structure of the metastable phase, while the conventionally estimated structure had separate layers of Ge and Te. The metastable and stable phases are very similar in that Te and Ge/Sb layers stack alternately to form the crystal. The major differences between these phases are: (i) the stable phase has pairs of adjacent Te layers that are not seen in the metastable phase and (ii) only the metastable phase contains vacancies of ca 20 at. % in the Ge/Sb layers.

scholarly journals Nanosized hydroxyapatite and β-tricalcium phosphate composite: Physico-chemical, cytotoxicity, morphological properties and in vivo trial

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Igor da Silva Brum ◽  
Jorge José de Carvalho ◽  
Jorge Luis da Silva Pires ◽  
Marco Antonio Alencar de Carvalho ◽  
Luiza Braga Ferreira dos Santos ◽  
...  
Keyword(s):  
Tricalcium Phosphate ◽  
Morphological Properties ◽  
Sinus Lift ◽  
Monoclinic Structure ◽  
Manufacturing Control ◽  
Physico Chemical ◽  
Synthetic Biomaterial ◽  
Trigonal Structure ◽  
High Level

AbstractThe objective of this work was to characterize the properties of a synthetic biomaterial composite with nanoparticles size (Blue Bone). This biomaterial is a composite recommended for dental and orthopedic grafting surgery, for guided bone regeneration, including maxillary sinus lift, fresh alveolus filling, and treatment of furcation lesions. The nano biomaterials surface area is from 30% to 50% higher than those with micro dimensions. Another advantage is that the alloplastic biomaterial has homogeneous properties due to the complete manufacturing control. The analyzed biomaterial composite was characterized by XRD, cytochemistry, scanning electron microscopy, porosimetry and in vivo experiments (animals). The results showed that the analyzed biomaterial composite has 78.76% hydroxyapatite [Ca5(PO4)3(OH)] with monoclinic structure, 21.03% β-tricalcium phosphate [β -Ca3(PO4)2] with trigonal structure and 0.19% of CaO with cubic structure, nanoparticles with homogeneous shapes, and nanoporosity. The in vivo experiments showed that the composite has null cytotoxicity, and the site of insertion biomaterials has a high level of vascularization and bone formation. The conclusion is that the synthetic biomaterial with Blue Bone designation presents characteristics suitable for use in grafting surgery applications.

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