Peptide-mediated deposition of nanostructured TiO2 into the periodic structure of diatom biosilica

2008 ◽  
Vol 23 (12) ◽  
pp. 3255-3262 ◽  
Author(s):  
Clayton Jeffryes ◽  
Timothy Gutu ◽  
Jun Jiao ◽  
Gregory L. Rorrer
Keyword(s):  
Titanium Dioxide ◽  
Electron Diffraction ◽  
Thermal Annealing ◽  
Periodic Structure ◽  
Outer Surface ◽  
Periodic Structures ◽  
Diatom Frustule ◽  
X Ray Diffraction ◽  
X Ray ◽  
Reported Study

Diatoms are single-celled algae that make silica shells called frustules that possess periodic structures ordered at the micro- and nanoscale. Nanostructured titanium dioxide (TiO2) was deposited onto the frustule biosilica of the diatom Pinnularia sp. Poly-l-lysine (PLL) conformally adsorbed onto surface of the frustule biosilica. The condensation of soluble Ti-BALDH to TiO2 by PLL-adsorbed diatom biosilica deposited 1.32 ± 0.17 g TiO2/g SiO2 onto the frustule. The periodic pore array of the diatom frustule served as a template for the deposition of the TiO2 nanoparticles, which completely filled the 200-nm frustule pores and also coated the frustule outer surface. Thermal annealing at 680 °C converted the as-deposited TiO2 to its anatase form with an average nanocrystal size of 19 nm, as verified by x-ray diffraction, electron diffraction, and SEM/TEM. This is the first reported study of directing the peptide-mediated deposition of TiO2 into a hierarchical nanostructure using a biologically fabricated template.

Bimolecular and Monomolecular Lipid Films: Selected Area Electron Diffraction

1969 ◽  
Vol 27 ◽  
pp. 338-339
Author(s):  
Robert M. Glaeser ◽  
David W. Deamer
Keyword(s):  
Electron Diffraction ◽  
Membrane Structure ◽  
Molecular Organization ◽  
Membrane Material ◽  
X Ray Diffraction ◽  
Membrane Systems ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Lipid Films ◽  
Ultimate Objective

In the investigation of the molecular organization of cell membranes it is often supposed that lipid molecules are arranged in a bimolecular film. X-ray diffraction data obtained in a direction perpendicular to the plane of suitably layered membrane systems have generally been interpreted in accord with such a model of the membrane structure. The present studies were begun in order to determine whether selected area electron diffraction would provide a tool of sufficient sensitivity to permit investigation of the degree of intermolecular order within lipid films. The ultimate objective would then be to apply the method to single fragments of cell membrane material in order to obtain data complementary to the transverse data obtainable by x-ray diffraction.

Isomorphous replacement in electron diffraction of wet crystals of rat hemoglobin

1983 ◽  
Vol 41 ◽  
pp. 446-447
Author(s):  
William F. Tivol ◽  
Murray Vernon King ◽  
D. F. Parsons
Keyword(s):  
Electron Diffraction ◽  
Heavy Atom ◽  
Isomorphous Substitution ◽  
X Ray Diffraction ◽  
Salt Solutions ◽  
X Ray ◽  
Isomorphous Replacement ◽  
Structure Factors ◽  
Diffraction Structure ◽  
The Mean

Feasibility of isomorphous substitution in electron diffraction is supported by a calculation of the mean alteration of the electron-diffraction structure factors for hemoglobin crystals caused by substituting two mercury atoms per molecule, following Green, Ingram & Perutz, but with allowance for the proportionality of f to Z3/4 for electron diffraction. This yields a mean net change in F of 12.5%, as contrasted with 22.8% for x-ray diffraction.Use of the hydration chamber in electron diffraction opens prospects for examining many proteins that yield only very thin crystals not suitable for x-ray diffraction. Examination in the wet state avoids treatments that could cause translocation of the heavy-atom labels or distortion of the crystal. Combined with low-fluence techniques, it enables study of the protein in a state as close to native as possible.We have undertaken a study of crystals of rat hemoglobin by electron diffraction in the wet state. Rat hemoglobin offers a certain advantage for hydration-chamber work over other hemoglobins in that it can be crystallized from distilled water instead of salt solutions.

Microstructure and crystal symmetry of Pb2Sr2(Y/Ca)Cu3O9−δ

1990 ◽  
Vol 48 (4) ◽  
pp. 64-65
Author(s):  
Y. P. Lin ◽  
J. S. Xue ◽  
J. E. Greedan
Keyword(s):  
Electron Diffraction ◽  
High Temperature Superconductors ◽  
Carbon Film ◽  
Basic Structure ◽  
Crystal Symmetry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Space Groups ◽  
New Family ◽  
Convergent Beam

A new family of high temperature superconductors based on Pb2Sr2YCu3O9−δ has recently been reported. One method of improving Tc has been to replace Y partially with Ca. Although the basic structure of this type of superconductors is known, the detailed structure is still unclear, and various space groups has been proposed. In our work, crystals of Pb2Sr2YCu3O9−δ with dimensions up to 1 × 1 × 0.25.mm and with Tc of 84 K have been grown and their superconducting properties described. The defects and crystal symmetry have been investigated using electron microscopy performed on crushed crystals supported on a holey carbon film.Electron diffraction confirmed x-ray diffraction results which showed that the crystals are primitive orthorhombic with a=0.5383, b=0.5423 and c=1.5765 nm. Convergent Beam Electron Diffraction (CBED) patterns for the and axes are shown in Figs. 1 and 2 respectively.

Microdomains in BaFeO3-y (0.35 < y < 0.50)

1990 ◽  
Vol 48 (4) ◽  
pp. 780-781
Author(s):  
M. Vallet-Regí ◽  
M. Parras ◽  
J.M. González-Calbet ◽  
J.C. Grenier
Keyword(s):  
Electron Diffraction ◽  
Chemical Analysis ◽  
Monoclinic Phase ◽  
Orthorhombic Phase ◽  
Total Iron ◽  
Zone Axis ◽  
Electron Micrograph ◽  
X Ray Diffraction ◽  
X Ray ◽  
Compositional Variations

BaFeO3-y compositions (0.35<y<0.50) have been investigated by means of electron diffraction and microscopy to resolve contradictory results from powder X-ray diffraction data.The samples were obtained by annealing BaFeO2.56 for 48 h. in the temperature range from 980°C to 1050°C . Total iron and barium in the samples were determined using chemical analysis and gravimetric methods, respectively.In the BaFeO3-y system, according to the electron diffraction and microscopy results, the nonstoichiometry is accommodated in different ways as a function of the composition (y):In the domain between BaFeO2.5+δBaFeO2.54, compositional variations are accommodated through the formation of microdomains. Fig. la shows the ED pattern of the BaFeO2.52 material along thezone axis. The corresponding electron micrograph is seen in Fig. 1b. Several domains corresponding to the monoclinic BaFeO2.50 phase, intergrow with domains of the orthorhombic phase. According to that, the ED pattern of Fig. 1a, can be interpreted as formed by the superposition of three types of diffraction maxima : Very strong spots corresponding to a cubic perovskite, a set of maxima due to the superposition of three domains of the monoclinic phase along [100]m and a series of maxima corresponding to three domains corresponding to the orthorhombic phase along the [100]o.

scholarly journals Dislocation Arrangement in a Thick LEO GaN Film on Sapphire

2000 ◽  
Vol 5 (S1) ◽  
pp. 97-103
Author(s):  
Kathleen A. Dunn ◽  
Susan E. Babcock ◽  
Donald S. Stone ◽  
Richard J. Matyi ◽  
Ling Zhang ◽  
...  
Keyword(s):  
High Resolution ◽  
Electron Diffraction ◽  
Threading Dislocations ◽  
X Ray Diffraction ◽  
Burgers Vector ◽  
X Ray ◽  
The Third ◽  
Dislocation Arrangement ◽  
Image Position ◽  
Gan Film

Diffraction-contrast TEM, focused probe electron diffraction, and high-resolution X-ray diffraction were used to characterize the dislocation arrangements in a 16µm thick coalesced GaN film grown by MOVPE LEO. As is commonly observed, the threading dislocations that are duplicated from the template above the window bend toward (0001). At the coalescence plane they bend back to lie along [0001] and thread to the surface. In addition, three other sets of dislocations were observed. The first set consists of a wall of parallel dislocations lying in the coalescence plane and nearly parallel to the substrate, with Burgers vector (b) in the (0001) plane. The second set is comprised of rectangular loops with b = 1/3 [110] (perpendicular to the coalescence boundary) which originate in the coalescence boundary and extend laterally into the film on the (100). The third set of dislocations threads laterally through the film along the [100] bar axis with 1/3<110>-type Burgers vectors These sets result in a dislocation density of ∼109 cm−2. High resolution X-ray reciprocal space maps indicate wing tilt of ∼0.5º.

Mev Ion Beam Synthesis of Well-Defined Buried 3C-Sic Layers in Silicon

1995 ◽  
Vol 396 ◽  
Author(s):  
J.K.N. Lindner ◽  
B. Götz ◽  
A. Frohnwieser ◽  
B. Stritzker
Keyword(s):  
Electron Diffraction ◽  
Depth Distribution ◽  
Ion Beam ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ion Beam Synthesis ◽  
Post Implantation

AbstractWell-defined, homogenous, deep-buried 3C-SiC layers have been formed in silicon by ion beam synthesis using MeV C+ ions. Layers are characterized by RBS/channeling, X-ray diffraction, x-sectional TEM and electron diffraction. The redistribution of implanted carbon atoms into a rectangular carbon depth distribution associated with a well-defined layer during the post-implantation anneal is shown to depend strongly on the existence of crystalline carbide precipitates in the as-implanted state.

Diffraction

2012 ◽  
Vol 20 (2) ◽  
pp. 7-7
Author(s):  
Charles Lyman
Keyword(s):  
Electron Diffraction ◽  
100Th Anniversary ◽  
Primary Phase ◽  
Phase Identification ◽  
X Rays ◽  
X Ray Diffraction ◽  
Identification Methods ◽  
X Ray ◽  
Structure Of Matter

This year marks the 100th anniversary of the discovery of X-ray diffraction and the 85th anniversary of electron diffraction (see Microscopy Pioneers). For most of the time since their introduction, microscopists have known these two techniques as the primary phase identification methods used in conjunction with various microscopies. However, these two diffraction methods also have played enormous roles in understanding the structure of matter, as well as the nature of both X rays and electrons.

Structure determination of modulated structures by powder X-ray diffraction and electron diffraction

2016 ◽  
Vol 3 (11) ◽  
pp. 1351-1362 ◽  
Author(s):  
Zhengyang Zhou ◽  
Lukáš Palatinus ◽  
Junliang Sun
Keyword(s):  
Electron Diffraction ◽  
Structure Determination ◽  
X Ray Diffraction ◽  
X Ray ◽  
Modulated Structures ◽  
Conventional Methods

The combination of PXRD and ED is applied to determine modulated structures which resist solution by more conventional methods.

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