Multiple-beam dynamic effects in Kikuchi patterns obtained at very high voltages in electron microscopy

1978 ◽  
Vol 38 (5) ◽  
pp. 503-518 ◽  
Author(s):  
A. Mazel ◽  
F. Ajustron
Keyword(s):  
Electron Microscopy ◽  
Dynamic Effects ◽  
Beam Dynamic ◽  
Multiple Beam ◽  
Very High

Electron Microscopy in Molecular Biology

1967 ◽  
Vol 25 ◽  
pp. 2-3
Author(s):  
Cecil E. Hall
Keyword(s):  
Electron Microscopy ◽  
Molecular Biology ◽  
Noise Level ◽  
Molecular Structures ◽  
Material Structure ◽  
The Arts ◽  
Shadow Casting ◽  
Electron Image ◽  
High Degree ◽  
Very High

The visualization of organic macromolecules such as proteins, nucleic acids, viruses and virus components has reached its high degree of effectiveness owing to refinements and reliability of instruments and to the invention of methods for enhancing the structure of these materials within the electron image. The latter techniques have been most important because what can be seen depends upon the molecular and atomic character of the object as modified which is rarely evident in the pristine material. Structure may thus be displayed by the arts of positive and negative staining, shadow casting, replication and other techniques. Enhancement of contrast, which delineates bounds of isolated macromolecules has been effected progressively over the years as illustrated in Figs. 1, 2, 3 and 4 by these methods. We now look to the future wondering what other visions are waiting to be seen. The instrument designers will need to exact from the arts of fabrication the performance that theory has prescribed as well as methods for phase and interference contrast with explorations of the potentialities of very high and very low voltages. Chemistry must play an increasingly important part in future progress by providing specific stain molecules of high visibility, substrates of vanishing “noise” level and means for preservation of molecular structures that usually exist in a solvated condition.

scholarly journals Dynamics and Temperature Simulation in Multi-Axis Milling

2008 ◽  
Vol 43 ◽  
pp. 89-96 ◽  
Author(s):  
Eduard Ungemach ◽  
Tobias Surmann ◽  
Andreas Zabel
Keyword(s):  
Surface Quality ◽  
Matrix Material ◽  
Ground Surface ◽  
Milling Process ◽  
Surface Structures ◽  
Dynamic Effects ◽  
Lightweight Construction ◽  
Surrounding Matrix ◽  
Simulation Systems ◽  
Very High

Lightweight extrusion profiles with reinforcement elements are promising news in the domain of lightweight construction. The machining of them suffers from several problems: Aside from the question of choosing a suitable tool, feed rate, and milling strategy, an excessive rise in temperature could lead to stress and even a distortion due to the differing thermal expansion of the reinforcement material and the surrounding matrix material. A simulation of the milling process could, in addition to force and collision calculations, recognize this case before manufacturing. For certain milling applications like seal surfaces, a certain roughness of the manufactured surface is necessary. In many other cases, a smooth surface of very high quality is desirable. Available simulation systems usually completely lack the simulation of dynamic effects, which have a great effect on the final surface quality, and therefore are not able to predict the resulting surface quality. In this paper simulation methods are presented that are capable of simulating the dynamic behavior of the tool in the milling process and the resulting flank and ground surface structures. Additionally, a fast temperature simulation for heterogeneous workpieces with reinforcement elements, which is based on the finite difference method and cellular automata, is introduced.

scholarly journals Application of spherical substrate to observe bacterial motility machineries by Quick-Freeze-Replica Electron Microscopy

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Eisaku Katayama ◽  
Yuhei O. Tahara ◽  
Clothilde Bertin ◽  
Satoshi Shibata
Keyword(s):  
Electron Microscopy ◽  
Molecular Mechanisms ◽  
Convex Surface ◽  
Structural Information ◽  
Cellular Functions ◽  
Crucial Issue ◽  
Flat Substrate ◽  
Functional Features ◽  
Surface Profiles ◽  
Very High

Abstract 3-D Structural information is essential to elucidate the molecular mechanisms of various biological machineries. Quick-Freeze Deep-Etch-Replica Electron Microscopy is a unique technique to give very high-contrast surface profiles of extra- and intra-cellular apparatuses that bear numerous cellular functions. Though the global architecture of those machineries is primarily required to understand their functional features, it is difficult or even impossible to depict side- or highly-oblique views of the same targets by usual goniometry, inasmuch as the objects (e.g. motile microorganisms) are placed on conventional flat substrates. We introduced silica-beads as an alternative substrate to solve such crucial issue. Elongated Flavobacterium and globular Mycoplasmas cells glided regularly along the bead’s surface, similarly to those on a flat substrate. Quick-freeze replicas of those cells attached to the beads showed various views; side-, oblique- and frontal-views, enabling us to study not only global but potentially more detailed morphology of complicated architecture. Adhesion of the targets to the convex surface could give surplus merits to visualizing intriguing molecular assemblies within the cells, which is relevant to a variety of motility machinery of microorganisms.

Development of a Double Tilt Specimen Heating Holder and its Application for the Study of Phase Transformation of Si3N4 During Sintering

1997 ◽  
Vol 3 (S2) ◽  
pp. 1085-1086
Author(s):  
T. Kamino ◽  
T. Yaguchi ◽  
M. Tomita ◽  
Y. Yasutomi ◽  
K. Hidaka
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Elevated Temperatures ◽  
Heating Element ◽  
High Melting ◽  
High Melting Point ◽  
Transmission Electron ◽  
High Resolution Tem ◽  
Metal Wires ◽  
Very High

The results of our previous studies revealed that the specimen heating holder with the heating elements of spiral shaped fine metal wires of high melting point enable us to observe high resolution transmission electron microscopy(TEM) images at elevated temperatures.In fact, the holder was applied for high resolution TEM study of a formation of SiC crystal at 1500°C and a surface reconstruction of Au deposited Si particle at 1000°C successfully. However, because the heating holder was single tilt type, there was a certain limitation in its application.In this paper, development of a double tilt specimen heating holder with a heating element of spiral shaped fine metal wire and its application for the study of microstructural changes of Si3N4 during sintering at very high temperature.Photograph of the newly developed double tilt specimen heating holder is shown in Fig. 1. The heating element is mounted on the electrically isolated tilting frame of the holder and the heating current is supplied via tilting rod which is also electrically isolated from other parts of the holder.

scholarly journals Perovskite CsPbBr3 Quantum Dots Prepared Using Discarded Lead–Acid Battery Recycled Waste

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 1117 ◽  
Author(s):  
Lung-Chien Chen ◽  
Ching-Ho Tien ◽  
Sin-Liang Ou ◽  
Kun-Yi Lee ◽  
Jianjun Tian ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Structural Characteristics ◽  
Film Surface ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Storage Batteries ◽  
Recycled Waste ◽  
Cspbbr3 Quantum Dots ◽  
Very High ◽  
Lead Acid

Perovskite CsPbBr3 quantum dot (CsPbBr3-QD) recovery was performed using lead scrap from lead storage batteries. The perovskite CsPbBr3-QD characteristics were analyzed using different PbO/recycled PbO2 ratios. Scanning electron microscopy (SEM) was used to observe the film surface morphology and cross-section. High-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) were used to observe the perovskite CsPbBr3-QDs’ structural characteristics. A photoluminescence (PL) measurement system was used to analyze the optical properties. The results show that lead scrap from lead–acid batteries as a material for perovskite CsPbBr3-QD production can be successfully synthesized. This saves material and also proves that recycling is valuable. The proposed approach is helpful for future material shortages and materials not easily accessible. Although the efficiency is not very high, this process will be purified using recycled lead in the future to achieve higher quantum yield.

Predation on copepods by an Alaskan cladorhizid sponge

2007 ◽  
Vol 87 (6) ◽  
pp. 1721-1726 ◽  
Author(s):  
Les Watling
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Lipid Content ◽  
Deep Sea ◽  
Prey Capture ◽  
Primary Process ◽  
High Lipid ◽  
Very High ◽  
Prey Items ◽  
Scanning Electron

Deep water cladorhizids are now generally thought to be carnivorous. While the methods of prey capture have been established for species of Asbestopluma, and perhaps Chondrocladia, information is sparse for species of Cladorhiza. The external morphology of the deep-sea Alaskan species, Cladorhiza corona, was examined immediately after collection, and then again later using scanning electron microscopy (SEM). All sponges examined had captured, and in most cases, fully encased, prey items which for the most part consisted of planktonic copepods. The hypothesis of this paper is that the primary process of prey capture is by means of a sticky substance and that prey stick to the sponge on contact. The abundant cladorhizid anisochelae do not seem to be arranged in a manner such that they can be used for prey capture as has been seen in Asbestopluma. Digestion of the prey occurs in a temporary cavity created by migrating sponge cells. Within this cavity lipid from the copepod is liberated, then absorbed and transported to the central part of the sponge. It is not known how much of the remaining tissue of the copepod is digested. Copepods have very high lipid content so their capture would provide the sponge with abundant energy from each prey item. The sponges seem to have their highest density in areas where bottom flow and migrating copepod numbers are both high.

An efficient routine for computing symmetric real spherical harmonics for high orders of expansion

2005 ◽  
Vol 38 (3) ◽  
pp. 501-504 ◽  
Author(s):  
Andrzej Kudlicki ◽  
Małgorzata Rowicka ◽  
Mirosław Gilski ◽  
Zbyszek Otwinowski
Keyword(s):  
Electron Microscopy ◽  
Spherical Harmonics ◽  
Efficient Method ◽  
Protein Crystallography ◽  
High Order ◽  
Linear Combinations ◽  
Crystallographic Symmetry ◽  
Stable Computation ◽  
Very High

A numerically efficient method of constructing symmetric real spherical harmonics is presented. Symmetric spherical harmonics are real spherical harmonics with built-in invariance with respect to rotations or inversions. Such symmetry-invariant spherical harmonics are linear combinations of non-symmetric ones. They are obtained as eigenvectors of an appropriate operator, depending on symmetry. This approach allows for fast and stable computation up to very high order symmetric harmonic bases, which can be used in e.g. averaging of non-crystallographic symmetry in protein crystallography or refinement of large viruses in electron microscopy.

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