Reversible Thermochromic Transition between Different J-Aggregate States of Amphiphilic Merocyanine Dye Crystallites

2000 ◽  
Vol 660 ◽  
Author(s):  
Noritaka Kato ◽  
Yasuaki Shin ◽  
Yoshiaki Uesu
Keyword(s):  
High Temperature ◽  
Absorption Band ◽  
Two Dimensional ◽  
Dye Molecules ◽  
X Ray Diffraction ◽  
X Ray ◽  
Langmuir Blodgett ◽  
Thermochromic Transition

ABSTRACTOn the subphase, which contains Cd2+ and Mg2+ ions, two-dimensional (2D) J-aggregate crystallites of merocyanine dye molecules exhibit a thermochromic transition. The J-aggregate absorption band of the low (LT) and high temperature (HT) phases are located at 620 and 595 nm, respectively. In order to clarify the in-plane structure of the 2D J-aggregate crystallites, grazing incident X-ray diffraction measurements were performed on the Langmuir-Blodgett multi-layers which consisted of the monolayers of LT and HT phases. It was revealed that the in-plane arrangement of the dye molecules is slightly different in the J-aggregate crystallites of LT and HT phases.

In Situ Study of Real Structure Effects on the Initial Oxidation of FeCrAl Alloys by Two-Dimensional High Temperature X-Ray Diffraction

2006 ◽  
Vol 522-523 ◽  
pp. 69-76 ◽  
Author(s):  
P. Kodjamanova ◽  
H. Fietzek ◽  
Maria Juez-Lorenzo ◽  
Vladislav Kolarik ◽  
Heike Hattendorf
Keyword(s):  
High Temperature ◽  
Formation Rate ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Initial Oxidation ◽  
X Ray ◽  
Growth Stresses ◽  
Fecral Alloys ◽  
Α Al2o3

In order to contribute to a better understanding of the processes, which occur in the structure of FeCrAl alloys during oxidation, in situ – studies by two-dimensional high temperature X-ray diffraction (2D-XRD) using a global area detector and grazing incidence with a monocapillary have been performed. The 2D-XRD yields simultaneously with the identification of the oxides and their formation kinetics information about the grain size, grain shape, stresses, texture as well as grain movements during the oxidation process of both oxide and metal. Two commercial FeCrAl alloys with different reactive element additions were investigated in the temperature range of 850°C to 1100°C. In the range of 1100°C already in the first 5 min the alloy grains become coarse and appear as single spots along the lateral profile in the 2D-XRD pattern. Dynamic displacement of these spots along the 2θ – axis during the exposure indicates the formation of stresses, which differ from grain to grain. Initially, re-crystallisation and grain growth dominate and grains disappear and new grains appear. On further exposure the grains twist continuously with 1° to 3° per hour, depending on the alloy. The “dancing grain” effect of the alloy is probably related with growth stresses in the oxide scale and influenced by the bulging of the foil. Simultaneously, α-Al2O3 is detected from the first pattern after 5 min and shows an enhanced formation rate in the first 15 min of the oxidation. The α-Al2O3 grains are with 0.3 to 0.4 4m extremely fine and, a dense well adherent scale is observed even after 1 h.

Synthese und Kristallstruktur von NiHo2(B2O5)2, das erste Nickellanthanoidborat mit einem 2∞(B2O5)4- -Anion / Synthesis and Crystal Structure of NiHo2(B2O5)2, the First Nickel Lanthanoid Borates with a (B2O5)4- Anion

1996 ◽  
Vol 51 (5) ◽  
pp. 677-680 ◽  
Author(s):  
Karsten Bluhm ◽  
André Wiesch
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Single Crystals ◽  
Oxygen Octahedra ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Synthesis And Crystal Structure ◽  
Space Group ◽  
X Ray ◽  
High Temperature Reactions

Single crystals of NiHo2(B2O5)2 were prepared by a B2O3 flux-technique in high temperature reactions at 1450 °C and investigated by X-ray diffraction. They crystallize in the space group C2h5-P21/c (Nr. 14) with a = 451.0(4); b = 724.8(3); c = 938.8(6) pm; β = 91,39( 1)°; Z = 2. The compound is isotypic to CuTb2 (B2O5)2 as well as to the gadolinite structure (FeY2(BeSiO5)2) and contains a two dimensional infinite anion with the formula 2∞ (B2O5)4-. The borate layers consist of four- and eight-membered rings of edge-sharing BO4 tetrahedra. The layers are connected via copper-centered elongated oxygen-octahedra and slightly distorted tetragonal HoO8 antiprisms.

Tubulin structure at intermediate resolution

1995 ◽  
Vol 53 ◽  
pp. 852-853
Author(s):  
K. H. Downing ◽  
S. G. Wolf ◽  
E. Nogales
Keyword(s):  
High Resolution ◽  
Structural Data ◽  
Therapeutic Drug ◽  
Zinc Ions ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Negative Stain ◽  
Functional Mechanisms ◽  
Tubulin Structure

Microtubules are involved in a host of critical cell activities, many of which involve transport of organelles through the cell. Different sets of microtubules appear to form during the cell cycle for different functions. Knowledge of the structure of tubulin will be necessary in order to understand the various functional mechanisms of microtubule assemble, disassembly, and interaction with other molecules, but tubulin has so far resisted crystallization for x-ray diffraction studies. Fortuitously, in the presence of zinc ions, tubulin also forms two-dimensional, crystalline sheets that are ideally suited for study by electron microscopy. We have refined procedures for forming the sheets and preparing them for EM, and have been able to obtain high-resolution structural data that sheds light on the formation and stabilization of microtubules, and even the interaction with a therapeutic drug.Tubulin sheets had been extensively studied in negative stain, demonstrating that the same protofilament structure was formed in the sheets and microtubules. For high resolution studies, we have found that the sheets embedded in either glucose or tannin diffract to around 3 Å.

High temperature X-ray diffraction investigation of an aluminium-silicon-corundum system

2007 ◽  
Vol 2007 (suppl_26) ◽  
pp. 369-374 ◽  
Author(s):  
D. Garipoli ◽  
P. Bergese ◽  
E. Bontempi ◽  
M. Minicucci ◽  
A. Di Cicco ◽  
...  
Keyword(s):  
High Temperature ◽  
X Ray Diffraction ◽  
X Ray

Synthesis and Structure of a Clathrated Two-Dimensional Metal-Organic Framework: [Cd(4,4'-bpy)2(H2O)2](ClO4)2·(L)2·H2O (L = Bis(1-pyrazinylethylidene)hydrazine)

2008 ◽  
Vol 73 (1) ◽  
pp. 24-31
Author(s):  
Dayu Wu ◽  
Genhua Wu ◽  
Wei Huang ◽  
Zhuqing Wang
Keyword(s):  
Metal Organic Framework ◽  
Channel Structure ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Guest Molecules ◽  
X Ray ◽  
Square Planar ◽  
Metal Organic ◽  
Aqueous Meoh ◽  
Organic Framework

The compound [Cd(4,4'-bpy)2(H2O)2](ClO4)2·(L)2 was obtained by the reaction of Cd(ClO4)2, bis(1-pyrazinylethylidene)hydrazine (L) and 4,4'-bipyridine in aqueous MeOH. Single-crystal X-ray diffraction has revealed its two-dimensional metal-organic framework. The 2-D layers superpose on each other, giving a channel structure. The square planar grids consist of two pairs of shared edges with Cd(II) ion and a 4,4'-bipyridine molecule each vertex and side, respectively. The square cavity has a dimension of 11.817 × 11.781 Å. Two guest molecules of bis(1-pyrazinylethylidene)hydrazine are clathrated in every hydrophobic host cavity, being further stabilized by π-π stacking and hydrogen bonding. The results suggest that the hydrazine molecules present in the network serve as structure-directing templates in the formation of crystal structures.

scholarly journals High-pressure synthesis and crystal structure of the mixed-cation borate Ga4In4B15O33(OH)3

2019 ◽  
Vol 74 (4) ◽  
pp. 357-363
Author(s):  
Daniela Vitzthum ◽  
Hubert Huppertz
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
High Temperature ◽  
Diffraction Data ◽  
X Ray Diffraction ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Mixed Cation ◽  
High Pressure High Temperature ◽  
Pressure Synthesis

AbstractThe mixed cation triel borate Ga4In4B15O33(OH)3 was synthesized in a Walker-type multianvil apparatus at high-pressure/high-temperature conditions of 12.5 GPa and 1300°C. Although the product could not be reproduced in further experiments, its crystal structure could be reliably determined via single-crystal X-ray diffraction data. Ga4In4B15O33(OH)3 crystallizes in the tetragonal space group I41/a (origin choice 2) with the lattice parameters a = 11.382(2), c = 15.244(2) Å, and V = 1974.9(4) Å3. The structure of the quaternary triel borate consists of a complex network of BO4 tetrahedra, edge-sharing InO6 octahedra in dinuclear units, and very dense edge-sharing GaO6 octahedra in tetranuclear units.

The Application of X-Ray Diffraction at Elevated Temperatures to Study the Mechanism of Formation of Sodium Tripolyphosphate

1961 ◽  
Vol 5 ◽  
pp. 276-284
Author(s):  
E. L. Moore ◽  
J. S. Metcalf
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Amorphous Phase ◽  
Elevated Temperatures ◽  
Sodium Tripolyphosphate ◽  
X Ray Diffraction ◽  
Mechanism Of Formation ◽  
X Ray ◽  
Temperature Form ◽  
High Temperature Form

AbstractHigh-temperature X-ray diffraction techniques were employed to study the condensation reactions which occur when sodium orthophosphates are heated to 380°C. Crystalline Na4P2O7 and an amorphous phase were formed first from an equimolar mixture of Na2HPO4·NaH2PO4 and Na2HPO4 at temperatures above 150°C. Further heating resulted in the formation of Na5P3O10-I (high-temperature form) at the expense of the crystalline Na4P4O7 and amorphous phase. Crystalline Na5P3O10-II (low-temperature form) appears after Na5P3O10-I.Conditions which affect the yield of crystalline Na4P2O7 and amorphous phase as intermediates and their effect on the yield of Na5P3O10 are also presented.

Mechanical Alloying Behavior in the Nb-Si, Ta-Si, and Nb-Ta-Si Systems

1988 ◽  
Vol 133 ◽  
Author(s):  
K. S. Kumar ◽  
S. K. Mannan
Keyword(s):  
High Temperature ◽  
Mechanical Alloying ◽  
Mechanical Milling ◽  
Room Temperature ◽  
Crystalline Compound ◽  
X Ray Diffraction ◽  
X Ray ◽  
Β Phase ◽  
Α Phase

ABSTRACTThe mechanical alloying behavior of elemental powders in the Nb-Si, Ta-Si, and Nb-Ta-Si systems was examined via X-ray diffraction. The line compounds NbSi2 and TaSi2 form as crystalline compounds rather than amorphous products, but Nb5Si3 and Ta5Si3, although chemically analogous, respond very differently to mechanical milling. The Ta5Si3 composition goes directly from elemental powders to an amorphous product, whereas Nb5Si3 forms as a crystalline compound. The Nb5Si3 compound consists of both the tetragonal room-temperature α phase (c/a = 1.8) and the tetragonal high-temperature β phase (c/a = 0.5). Substituting increasing amounts of Ta for Nb in Nb5Si3 initially stabilizes the α-Nb5Si3 structure preferentially, and subsequently inhibits the formation of a crystalline compound.

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