scholarly journals Structural and dynamic aspects related to oligomerization of apo SOD1 and its mutants

2009 ◽  
Vol 106 (17) ◽  
pp. 6980-6985 ◽  
Author(s):  
Lucia Banci ◽  
Ivano Bertini ◽  
Mirela Boca ◽  
Vito Calderone ◽  
Francesca Cantini ◽  
...  
Keyword(s):  
Solvent Accessibility ◽  
Structural Disorder ◽  
Free Form ◽  
X Ray Diffraction ◽  
X Ray ◽  
Conformational Variability ◽  
Metal Free ◽  
Loop Regions ◽  
Lateral Sclerosis ◽  
Apo State

The structural and dynamical properties of the metal-free form of WT human superoxide dismutase 1 (SOD1) and its familial amyotrophic lateral sclerosis (fALS)-related mutants, T54R and I113T, were characterized both in solution, through NMR, and in the crystal, through X-ray diffraction. We found that all 3 X-ray structures show significant structural disorder in 2 loop regions that are, at variance, well defined in the fully-metalated structures. Interestingly, the apo state crystallizes only at low temperatures, whereas all 3 proteins in the metalated form crystallize at any temperature, suggesting that crystallization selects one of the most stable conformations among the manifold adopted by the apo form in solution. Indeed, NMR experiments show that the protein in solution is highly disordered, sampling a large range of conformations. The large conformational variability of the apo state allows the free reduced cysteine Cys-6 to become highly solvent accessible in solution, whereas it is essentially buried in the metalated state and the crystal structures. Such solvent accessibility, together with that of Cys-111, accounts for the tendency to oligomerization of the metal-free state. The present results suggest that the investigation of the solution state coupled with that of the crystal state can provide major insights into SOD1 pathway toward oligomerization in relation to fALS.

Structural Properties Of Co/Re Superlattices

1991 ◽  
Vol 238 ◽  
Author(s):  
Y. Huai ◽  
R. W. Cochrane ◽  
Y. Shi ◽  
H. E. Fischer ◽  
M. Sutton
Keyword(s):  
Structural Disorder ◽  
Multilayer Films ◽  
Film Plane ◽  
X Ray Diffraction ◽  
X Ray ◽  
Bilayer Films ◽  
Out Of Plane ◽  
Reflectivity Data ◽  
Sharp Interfaces ◽  
Good Agreement

ABSTRACTThe structures of equal-thickness Co/Re multilayer films and several Co/Re bilayer films have been investigated by X-ray diffraction at low and high angles. Analysis of low-angle reflectivity data from bilayer films indicates that interfacial intermixing is limited to three monolayers and that the two interfacial configurations are different. The high-angle X-ray diffraction data show that multilayer films have coherent interfaces and a highly textured structure with hep [002] orientations normal to the film plane for periods 21 Å ≤ Λ ≤220 Å. Detailed structures have been determined by fitting the X-ray spectra to calculated ones using a trapezoidal model. The results indicate that samples with 42 Å≤ Λ ≤220 Å have relatively sharp interfaces, in good agreement with the bilayer results. In addition, an out-of-plane expansion of the Co (002) layer is observed in samples with large Λ and results from structural disorder leading to a reduced atomic density. For Λ <21 Å the interfaces arise from the rougher surfaces of the deposited layers.

Gallium-containing Heusler phases ScRh2Ga, ScPd2Ga, TmRh2Ga and LuRh2Ga – magnetic and solid state NMR-spectroscopic characterization

2017 ◽  
Vol 72 (8) ◽  
pp. 609-615
Author(s):  
Lukas Heletta ◽  
Stefan Seidel ◽  
Christopher Benndorf ◽  
Hellmut Eckert ◽  
Rainer Pöttgen
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Spectroscopic Characterization ◽  
Structural Disorder ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Phase Purity ◽  
X Ray ◽  
Arc Melting ◽  
Pauli Paramagnetism

AbstractThe gallium-containing Heusler phases ScRh2Ga, ScPd2Ga, TmRh2Ga and LuRh2Ga have been synthesized by arc-melting of the elements followed by different annealing sequences to improve phase purity. The samples have been studied by powder X-ray diffraction. The structures of Lu0.97Rh2Ga1.03 (Fm3̅m, a=632.94(5) pm, wR2=0.0590, 46 F2 values, seven variables) and Sc0.88Rh2Ga1.12 (a=618.91(4) pm, wR2=0.0284, 44 F2 values, six variables) have been refined from single crystal X-ray diffractometer data. Both gallides show structural disorder through Lu/Ga and Sc/Ga mixing. Temperature dependent magnetic susceptibility measurements showed Pauli paramagnetism for ScRh2Ga, ScPd2Ga, and LuRh2Ga and Curie-Weiss paramagnetism for TmRh2Ga. 45Sc and 71Ga solid state MAS NMR spectroscopic investigations of the Sc containing compounds confirmed the site mixing effects typically observed for Heusler phases. The data indicate that the effect of mixed Sc/Ga occupancy is significantly stronger in ScRh2Ga than in ScPd2Ga.

Effects of Indium Incorporation on the Optical Properties of ZnO Films

2006 ◽  
Vol 11-12 ◽  
pp. 159-162 ◽  
Author(s):  
Yong Ge Cao ◽  
Lei Miao ◽  
Sakae Tanemura ◽  
Yasuhiko Hayashi ◽  
Masaki Tanemura
Keyword(s):  
Optical Transmission ◽  
Full Width Half Maximum ◽  
Structural Disorder ◽  
Band Gaps ◽  
Zno Films ◽  
Photoluminescence Spectra ◽  
X Ray Diffraction ◽  
X Ray ◽  
Optical Band Gaps ◽  
Xrd Patterns

Transparent indium-doped ZnO (IZO) films with low In content (<6at%) were fabricated through radio-frequency (rf) helicon magnetron sputtering. Formation of In-Zn-O solid solution was confirmed by X-ray diffraction (XRD) patterns. Incorporation of indium into ZnO films enhances the optical transmission in the visible wavelength. The optical band-gaps slightly increase from 3.25eV (ZnO) to 3.28eV (In0.04Zn0.96O) and to 3.30eV (In0.06Zn0.94O) due to Burstain-Moss effect. The Urbach tail parameter E0, which is believed to be a function of structural disorder, increases from 79meV (ZnO), to 146meV (In0.04Zn0.96O), and to 173meV (In0.06Zn0.94O), which is consistent with increase of Full-Width Half-Maximum (FWHM) in corresponding XRD patterns. Decreasing in crystal quality with increasing indium concentration is also confirmed by photoluminescence spectra.

Charge transfer associated with lithium insertion in Mo1−yNbyS2 layered compounds

1984 ◽  
Vol 62 (1) ◽  
pp. 10-14 ◽  
Author(s):  
M. A. Py ◽  
R. R. Haering
Keyword(s):  
Voltage Drop ◽  
Structural Disorder ◽  
Host Lattice ◽  
Layered Compounds ◽  
Electrochemical Cells ◽  
X Ray Diffraction ◽  
Electronic Density ◽  
X Ray ◽  
Critical Composition ◽  
Trigonal Prismatic

The Mo1−yNbyS2 layered compounds form solid solutions. The coordination of the Mo and Nb atoms by S atoms is trigonal prismatic over the entire range of composition, 0 ≤ y ≤ 1. The [Formula: see text] band, separated from the other d-bands by a bandgap of the order of 1 eV, contains y empty states per formula unit. For y ≤ 0.6, Li/LixMo1−yNbyS2 electrochemical cells reveal a sharp voltage drop of V(x) at a critical composition x which is correlated to y by [Formula: see text]. This result clearly establishes the transfer of one electron per intercalated lithium (x ≤ 0.6) to the [Formula: see text] band of the host.Electrochemical cells, made with samples whose X-ray diffraction spectra suggest the presence of structural disorder in the host lattice, show a less abrupt voltage drop near xc, in qualitative agreement with the influence of disorder on the electronic density-of-states distribution N(E) near a band edge. The origin of the voltage drop observed for LixMo0.2Nb0.8S2 is not fully established.

Conformational Comparisons Between Phenoxyacetic Acid Derivatives in Adducts and in the Free Form

1999 ◽  
Vol 52 (7) ◽  
pp. 695 ◽  
Author(s):  
Graham Smith ◽  
Catherine J. Cooper ◽  
Veena Chauhan ◽  
Daniel E. Lynch ◽  
Simon Parsons ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Single Crystal ◽  
Free Acid ◽  
Molecular Complexes ◽  
The Other ◽  
Free Form ◽  
Phenoxyacetic Acid ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dichlorophenoxy Acetic Acid

Six molecular complexes containing the herbicidally active (2,4-dichlorophenoxy)acetic acid (2,4-d) and (2,4,5-trichlorophenoxy)acetic acid (2,4,5-t) have been prepared and studied by using single-crystal X-ray diffraction techniques. These adduct structures are 2,4-d with 4,4′-dipyridine (2 : 1 complex), and 2,4,5-t with respectively 5-nitroquinoline (1 : 1), 4,4′-dipyridine (2 : 1), 2-amino-2-thiazoline (1 : 1), 2-aminobenzothiazole (1 : 1) and 2-amino-5-ethyl-1,3,4-thiadiazole (1 : 1). The conformations of the phenoxyacetic acid molecules were found to be either synclinal (in three cases) or antiperiplanar (in the other three cases). A general review is also made about the conformational aspects of previously reported adducts of phenoxyacetic acid derivatives and how they compare to their free acid structures.

Single-crystal X-ray diffraction, EMPA, FTIR and X-ray photoelectron spectroscopy study of narsarsukite from Murun Massif, Russia

2017 ◽  
Vol 81 (2) ◽  
pp. 339-354 ◽  
Author(s):  
E. Schingaro ◽  
E. Mesto ◽  
M. Lacalamita ◽  
F. Scordari ◽  
E. Kaneva ◽  
...  
Keyword(s):  
Single Crystal ◽  
Photoelectron Spectroscopy ◽  
Chemical Study ◽  
Structural Disorder ◽  
Crystal Chemical ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Alkaline Massif

AbstractA crystal chemical study of narsarsukite from the Murun alkaline massif, Russia has been carried out combining single-crystal X-ray diffraction, electron microprobe analyses, micro-Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The narsarsukite single crystals are tetragonal (space group I4/m) with unit-cell parameters: 10.7140(1) ≤ a ≤ 10.7183(2) Å and 7.9478(1) ≤ c ≤ 7.9511(1) Å. The XPS analysis showed that Fe occurs in the mineral as Fe3+, whereas the FTIR spectrum showed that the sample studied is anhydrous. The average crystal chemical formula of the Murun narsarsukite is: Na2.04K0.01(V0.015+Ti0.74Zr0.01Al0.01Fe0.223+Mg0.01)1.00Si4.00(O10.74F0.23OH0.03)11.00. Structural disorder at octahedral and interstitial sites was modelled and also discussed in consideration of the main substitutional mechanism Ti4+ + O2– ↔ Fe3+ + (F–, OH–) active in the structure of the mineral.

Non-Stoichiometry and Structure of SrCe1-xYbxO3 Perovskite-Type Oxides

1996 ◽  
Vol 453 ◽  
Author(s):  
Igor Kosacki ◽  
Mark Shumsky ◽  
Harlan U. Anderson
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Charge Carrier ◽  
Structural Properties ◽  
Electrical Transport ◽  
Structural Disorder ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structural And Electrical Properties ◽  
Perovskite Type

AbstractThe structural and electrical properties of SrCe1-xYbxO3 ceramics have been studied as a function of temperature and Yb-concentration using x-ray diffraction and impedance techniques. The influence of Yb-dopants on electrical transport and structural disorder has been studied. A correlation between the structural properties, electrical conductivity is observed and discussed. These measurements allow us to determine the mechanism of charge carrier compensation and also the concentration and mobility of the electrical species.

scholarly journals Structural Disorder in Layered Hybrid Halide Perovskites: Types of Stacking Faults, Influence on Optical Properties and Their Suppression by Crystallization Engineering

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3333
Author(s):  
Andrei S. Tutantsev ◽  
Ekaterina I. Marchenko ◽  
Natalia N. Udalova ◽  
Sergey A. Fateev ◽  
Eugene A. Goodilin ◽  
...  
Keyword(s):  
Optical Properties ◽  
Stacking Faults ◽  
Structural Disorder ◽  
Model System ◽  
Thickness Variation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Simple Addition ◽  
Halide Perovskites ◽  
Xrd Patterns

Layered hybrid halide perovskites (LHHPs) are an emerging type of semiconductor with a set of unique optoelectronic properties. However, the solution processing of high-quality LHHPs films with desired optical properties and phase composition is a challenging task, possibly due to the structural disorder in the LHHP phase. Nevertheless, there is still a lack of experimental evidence and understanding of the nature of the structural disorder in LHHPs and its influence on the optical properties of the material. In the current work, using 2D perovskites (C4H9NH3)2(CH3NH3)n−1PbnI3n+1 (further BA2MAn−1PbnI3n+1) with n = 1–4 as a model system, we demonstrate that deviations in LHHPs optical properties and X-ray diffraction occur due to the presence of continuous defects—Stacking Faults (SFs). Upon analyzing the experimental data and modeled XRD patterns of a possible set of stacking faults (SFs) in the BA2MAPb2I7 phase, we uncover the most plausible type of SFs, featured by the thickness variation within one perovskite slab. We also demonstrate the successful suppression of SFs formation by simple addition of BAI excess into BA2MAn−1PbnI3n+1 solutions.

scholarly journals Synthesis of Nitroxide Diradical Using a New Approach

Molecules ◽  
2020 ◽  
Vol 25 (11) ◽  
pp. 2701 ◽  
Author(s):  
Pavel Fedyushin ◽  
Tatyana Rybalova ◽  
Nargiz Asanbaeva ◽  
Elena Bagryanskaya ◽  
Alexey Dmitriev ◽  
...  
Keyword(s):  
Quantum Chemical ◽  
Total Yield ◽  
Exchange Interactions ◽  
Free Form ◽  
Dihedral Angles ◽  
X Ray Diffraction ◽  
New Approach ◽  
X Ray ◽  
Tert Butyl ◽  
Organic Systems

A new synthetic pathway to diradical organic systems is proposed. The effectiveness of this approach was exemplified by the synthesis of a new nitroxide diradical. An interaction of perfluorobiphenyl with lithium tert-butylamide, followed by oxidation of the thusly formed N4,N4′-di-tert-butyl-2,2′,3,3′,5,5′,6,6′-octafluorobiphenyl-4,4′-diamine with meta-chloroperoxybenzoic acid, led to the polyfluorinated nitroxide diradical, N,N′-(perfluorobiphenyl-4,4′-diyl)bis(N-tert-butyl(oxyl)amine), with a good total yield. The polyfluorinated diradical is stable and can be isolated in free form and completely characterized. The structure of the nitroxide diradical was proved by single-crystal X-ray diffraction analysis. According to the X-ray diffraction data, the diradical is considerably twisted: dihedral angles between the planes of the nitroxide groups and aromatic cycles are 65.1° and 69.5°, and between aromatic cycles 52.6°. Quantum chemical calculations predict well-balanced size of both intramolecular and intermolecular exchange interactions with J from −2.65 to −1.14 cm−1.

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