Mutual Structure Model for improving vessel quality in X-ray angiography

2018 ◽  
Author(s):  
Shaoyan Xia ◽  
Haogang Zhu
Keyword(s):  
Structure Model ◽  
X Ray ◽  
Mutual Structure

scholarly journals Surface Engineering of Top7 to Facilitate Structure Determination

2022 ◽  
Vol 23 (2) ◽  
pp. 701
Author(s):  
Yuki Ito ◽  
Takuya Araki ◽  
Shota Shiga ◽  
Hiroyuki Konno ◽  
Koki Makabe
Keyword(s):  
Structure Determination ◽  
Surface Engineering ◽  
De Novo ◽  
Crystal Packing ◽  
Structure Model ◽  
X Ray ◽  
Hexahistidine Tag ◽  
Model Protein ◽  
Β Sheet ◽  
Packing Interactions

Top7 is a de novo designed protein whose amino acid sequence has no evolutional trace. Such a property makes Top7 a suitable scaffold for studying the pure nature of protein and protein engineering applications. To use Top7 as an engineering scaffold, we initially attempted structure determination and found that crystals of our construct, which lacked the terminal hexahistidine tag, showed weak diffraction in X-ray structure determination. Thus, we decided to introduce surface residue mutations to facilitate crystal structure determination. The resulting surface mutants, Top7sm1 and Top7sm2, crystallized easily and diffracted to the resolution around 1.7 Å. Despite the improved data, we could not finalize the structures due to high R values. Although we could not identify the origin of the high R values of the surface mutants, we found that all the structures shared common packing architecture with consecutive intermolecular β-sheet formation aligned in one direction. Thus, we mutated the intermolecular interface to disrupt the intermolecular β-sheet formation, expecting to form a new crystal packing. The resulting mutant, Top7sm2-I68R, formed new crystal packing interactions as intended and diffracted to the resolution of 1.4 Å. The surface mutations contributed to crystal packing and high resolution. We finalized the structure model with the R/Rfree values of 0.20/0.24. Top7sm2-I68R can be a useful model protein due to its convenient structure determination.

scholarly journals `Pd20Sn13' revisited: crystal structure of Pd6.69Sn4.31

2015 ◽  
Vol 71 (7) ◽  
pp. 807-809 ◽  
Author(s):  
Wilhelm Klein ◽  
Hanpeng Jin ◽  
Viktor Hlukhyy ◽  
Thomas F. Fässler
Keyword(s):  
Crystal Structure ◽  
Title Compound ◽  
Original Structure ◽  
Site Symmetry ◽  
Structure Model ◽  
Reaction Route ◽  
X Ray ◽  
Anisotropic Displacement Parameters ◽  
Solid State Reaction Route ◽  
Atomic Coordinates

The crystal structure of the title compound was previously reported with composition `Pd20Sn13' [Sarahet al.(1981).Z. Metallkd,72, 517–520]. For the original structure model, as determined from powder X-ray data, atomic coordinates from the isostructural compound Ni13Ga3Ge6were transferred. The present structure determination, resulting in a composition Pd6.69Sn4.31, is based on single crystal X-ray data and includes anisotropic displacement parameters for all atoms as well as standard uncertainties for the atomic coordinates, leading to higher precision and accuracy for the structure model. Single crystals of the title compound were obtainedviaa solid-state reaction route, starting from the elements. The crystal structure can be derived from the AlB2type of structure after removing one eighth of the atoms at the boron positions and shifting adjacent atoms in the same layer in the direction of the voids. One atomic site is partially occupied by both elements with a Pd:Sn ratio of 0.38 (3):0.62 (3). One Sn and three Pd atoms are located on special positions with site symmetry 2. (Wyckoff letter 3aand 3b).

scholarly journals Low-Temperature Ordering in the Cluster Compound (Bi8)Tl[AlCl4]3

Inorganics ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 45 ◽  
Author(s):  
Maximilian Knies ◽  
Martin Kaiser ◽  
Mai Lê Anh ◽  
Anastasia Efimova ◽  
Thomas Doert ◽  
...  
Keyword(s):  
Cluster Compound ◽  
Structure Model ◽  
X Ray Diffraction ◽  
Hexagonal Symmetry ◽  
Threefold Axis ◽  
Space Group ◽  
X Ray ◽  
A Chain ◽  
Symmetry Space ◽  
Symmetry Space Group

The reaction of Bi, BiCl3, and TlCl in the ionic liquid [BMIm]Cl·4AlCl3 (BMIm = 1-n-butyl-3-methylimidazolium) at 180 °C yielded air-sensitive black crystals of (Bi8)Tl[AlCl4]3. X-ray diffraction on single crystals at room temperature revealed a structure containing [ Tl ( AlCl 4 ) 3 ] ∞ 1 2 − strands separated by isolated Bi82+ square antiprisms. The thallium(I) ion is coordinated by twelve Cl− ions of six [AlCl4]− groups, resulting in a chain of face-sharing [TlCl12]11− icosahedra. The Bi82+ polycation is disordered, simulating a threefold axis through its center and overall hexagonal symmetry (space group P63/m). Slowly cooling the crystals to 170 K resulted in increased order in the Bi8 cluster orientations. An ordered structure model in a supercell with a’ = 2a, b’ = 2b, c’ = 3c and the space group P65 was refined. The structure resembles a hexagonal perovskite, with complex groups in place of simple ions.

Utilizing a unified structure model in (3 + 1)-dimensional superspace to identify a homologous phase (Ga1−αAlα)2O3(ZnO) m in ZnO-based thermoelectric composites

2020 ◽  
Vol 53 (6) ◽  
pp. 1542-1549
Author(s):  
Yuichi Michiue ◽  
Hyoung-Won Son ◽  
Takao Mori
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Composite Materials ◽  
The Other ◽  
Structure Model ◽  
X Ray Diffraction ◽  
X Ray ◽  
Long Period ◽  
Profile Fitting ◽  
Doped Zno

A unified structure model in (3 + 1)-dimensional superspace proved suitable for identification of a homologous phase (Ga1−αAlα)2O3(ZnO) m by the profile fitting of powder X-ray diffraction intensities for thermoelectric composite materials in the pseudoternary system ZnO–Al2O3–Ga2O3. A homologous compound of the phase parameter m ≃ 37 was found to coexist with (Al,Ga)-doped ZnO in samples sintered at 1723 K in air. The thermoelectric properties of the composite materials were closely related to the phase fractions. The higher the phase fraction of (Al,Ga)-doped ZnO with the wurtzite structure, the higher the electrical conductivity. On the other hand, the homologous compound with the long-period structure was effective in lowering the thermal conductivity of the materials.

Accuracy of XRPD QPA using the combined Rietveld–RIR method

2000 ◽  
Vol 33 (2) ◽  
pp. 267-278 ◽  
Author(s):  
Alessandro F. Gualtieri
Keyword(s):  
Crystal Structure ◽  
Phase Composition ◽  
Incoherent Scattering ◽  
Quantitative Phase Analysis ◽  
Polycrystalline Materials ◽  
Structure Model ◽  
Thermal Displacement ◽  
Model Assumption ◽  
Pyroclastic Rocks ◽  
X Ray

QPA (quantitative phase analysis) of polycrystalline materials using XRPD (X-ray powder diffraction) can be performed using the combined Rietveld and reference intensity ratio (RIR) methods, providing an estimate of both the crystalline and the amorphous phase in a mixture. Although the accuracy of estimates of the phase composition of simple ternary or quaternary mixtures is generally very good, uncertainties remain and bias the accuracy of phase determinations in complex systems such as pyroclastic rocks, which may contain two or more zeolite species, a number of other phases (generally up to four or five), and glass. The contribution of the incoherent scattering, biasing accuracy, in the glass determination has been discussed in an earlier work on the modal analysis of pyroclastic rocks [Gualtieri (1996).Powder Diffr.11, 97–106]. In this work, the assumption of the crystal structure, the influence of the spike addition, background and atomic (thermal) displacement parameters are discussed. It is shown that the structure-model assumption no longer holds for systems containing complex phases such as zeolites, as the accuracy is degraded and, as far as the influence of the added spike is concerned, there is an underestimation of the glass content with increasing amounts of added spike.

A Stand-Alone Mesoporous Crystal Structure Model from in situ X-ray Diffraction: Nitrogen Adsorption on 3 D Cagelike Mesoporous Silica SBA-16

2012 ◽  
Vol 18 (33) ◽  
pp. 10300-10311 ◽  
Author(s):  
Keiichi Miyasaka ◽  
Hiroko Hano ◽  
Yoshiki Kubota ◽  
Yangzheng Lin ◽  
Ryong Ryoo ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Mesoporous Silica ◽  
Nitrogen Adsorption ◽  
Structure Model ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals Synthesis, crystal structure and charge-distribution validation of β-Na4Cu(MoO4)3adopting the alluadite structure-type

2016 ◽  
Vol 72 (8) ◽  
pp. 1103-1107 ◽  
Author(s):  
Wassim Dridi ◽  
Mohamed Faouzi Zid
Keyword(s):  
Charge Distribution ◽  
Three Dimensional ◽  
Structure Type ◽  
Solid State Reactions ◽  
Site Symmetry ◽  
Structure Model ◽  
X Ray Diffraction ◽  
New Variety ◽  
X Ray ◽  
Bond Valence Sum

Single crystals of a new variety of tetrasodium copper(II) tris[molybdate(VI)], Na4Cu(MoO4)3, have been synthesized by solid-state reactions and characterized by single-crystal X-ray diffraction. This alluaudite structure-type is characterized by the presence of infinite layers of composition (Cu/Na)2Mo3O14parallel to the (100) plane, which are linked by MoO4tetrahedra, forming a three-dimensional framework containing two types of hexagonal channels in which Na+cations reside. The Cu2+and Na2+cations are located at the same general site with occupancies of 0.5. All atoms are on general positions except for one Mo, two Na (site symmetry 2) and another Na (site symmetry -1) atom. One O atom is split into two separate positions with occupancies of 0.5. The title compound is isotypic with Na5Sc(MoO4)4and Na3In2As3O12. The structure model is supported by bond-valence-sum (BVS) and charge-distribution CHARDI methods. β-Na4Cu(MoO4)3is compared and discussed with the K4Cu(MoO4)3and α-Na4Cu(MoO4)3structures.

Study of In-Plane Orientation of Epitaxial Si Films Grown on 6H-SiC(0001)

2016 ◽  
Vol 858 ◽  
pp. 221-224
Author(s):  
Lian Bi Li ◽  
Zhi Ming Chen
Keyword(s):  
Vapour Deposition ◽  
Lattice Mismatch ◽  
Lattice Structure ◽  
Chemical Vapour ◽  
Structure Model ◽  
X Ray Diffraction ◽  
X Ray ◽  
Plane Orientation ◽  
Pressure Chemical ◽  
Si Films

The Si/SiC heterojunctions were prepared on 6H-SiC(0001) by low-pressure chemical vapour deposition at 900°C. X-ray diffraction was employed to investigate the in-plane orientation of Si/SiC heterojunctions. A FCC-on-HCP parallel epitaxy was achieved for the Si(111)/SiC(0001) heterostructure with a growth temperature of 900°C and the in-plane orientation relationship was [01-1]Si//[11-20]6H-SiC. Based on the in-plane orientation characterizations, the lattice-structure model of the Si/6H-SiC heterostructure was constructed. It is shown that when the in-plane orientation was (111)[01-1]Si//(0001)[11-20]6H-SiC, the Si/6H-SiC interface had a 4:5 Si-to-SiC matching mode with a residual lattice-mismatch of 0.26%, and the misfit dislocation density at the Si/SiC interface was calculated as 0.487×1014cm-2.

Crystal Structure of K6Nb44O113 from HREM

1990 ◽  
Vol 48 (1) ◽  
pp. 42-43
Author(s):  
F.H. Li ◽  
C.M. Teng ◽  
J.J. Hu ◽  
F. Nagata ◽  
C. Tsuruta
Keyword(s):  
Crystal Structure ◽  
Electron Diffraction ◽  
Crystal Size ◽  
Fold Axis ◽  
Structure Model ◽  
X Ray Diffraction ◽  
X Ray ◽  
Tetragonal System ◽  
Small Crystal Size ◽  
Different Shapes

Different results about the crystal structure of K6Nb44O113 (KNO) were obtained by X-ray diffraction analysis[1,2]. This might be due to the small crystal size and the impurity of crystalline powders. Such sample are suitable for HREM investigation. Teng et al. studied the crystal by electron diffraction and HREM[3]. They compared the image of KNO with the structure model of Rb3Nb54O146(RNO) proposed by Gatehouse et al.[4]. The latter’s structure which is formed by Nb-O octahedra belongs to the tetragonal system and contains tunnels of different shapes along the four-fold axis(Fig.1). An image of KNO given by Teng et al. shows four-leaf and three-leaf shaped bright dots whose arrangement is in agreement with that of heptagonal and hexagonal tunnels in the structure of RNO respectively. Although Teng et al. proposed that the crystal structure of KNO might also be formed by Nb-O octahedra and contains various tunnels as RNO, they concluded that the symmetry of KNO should be lower than that of RNO. In this abstract it is reported that the crystal structure of KNO is isomorphic to that of RNO as well as that of CsxNb54(O,F)146[5].

About the degree of hydration in potassiumtrisoxalatochromate hydrate

2005 ◽  
Vol 220 (11) ◽  
Author(s):  
Chunhua Hu ◽  
Gernot Heger ◽  
Irmgard Kalf ◽  
Ullrich Englert
Keyword(s):  
Neutron Diffraction ◽  
Water Molecules ◽  
Structure Model ◽  
Hydrogen Atoms ◽  
Neutron Data ◽  
X Ray ◽  
Degree Of Hydration ◽  
Thermogravimetric Data ◽  
Hydration Model ◽  
Good Agreement

AbstractData obtained from single crystal X-ray and neutron diffraction experiments have been combined with results from thermogravimetry in order to derive an improved structure model for potassium tris(oxalato)chromate hydrate. The degree of hydration for this compound has been reinvestigated: Earlier work assumed a trihydrate stoichiometry and had to accept an unusually short K···O distance of 2.3 Å. Our neutron data reveal the position of the hydrogen atoms in the water molecules; they prove that abnormally short separations between a cation and atoms of a water molecule can only occur between sites of mutually exclusive occupancy and hence remain without chemical relevance. Closest K···O distances in our revised hydration model amount to 2.6 Å, in good agreement with expectation. Both diffraction experiments and thermogravimetric data agree with the stoichiometry K

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