The sub-membrane reticulum of the human erythrocyte: a scanning electron microscope study

A web-like reticulum underlying the human erythrocyte membrane was studied at a resolution of 5-10 nm by means of scanning electron microscope. The network was visualized in isolated membranes (ghosts) torn open to reveal their interior space and in residues derived from ghosts extracted with Triton X-100. It formed a continuous (rather than patchy) cover over the entire cytoplasmic surface, except where lifted off or torn away. Filaments (5-40 nm in diameter), annular figures (40-60 nm in diameter), and nodes (30-100 nm in diameter) were prominent in different networks. The dimensions of the filaments and the interstices in the reticulum varied with conditions, suggesting that the network has elastic properties. This reticulum is probably related to the erythrocyte membrane proteins spectrin and actin.     

Confocal microscopy, computer modeling, and quantification of glomerular vascular corrosion casts.

Corrosion-casted capillary systems of the kidney glomerulus were imaged with confocal microscopy because of the fluorescence properties of the casting plastic. Acquisition of a z-series through the glomerular capillaries provided three-dimensional data sets from which surface-rendered models were generated. These models could be rotated and viewed from any angle and also contained quantitative information allowing cast surface area and volume measurements to be calculated. The computer-generated models were also skeletonized to form a one-voxel-thick skeleton of the original model. The skeleton exhibited the three-dimensional topology and network of the capillary bed, and interior capillary relations could also be viewed. Quantitative information such as the total capillary length and number of capillary intersects was calculated from the skeletonized model. Extending this method to noncorroded kidney specimens revealed not only the casted vessels but also cellular features of the adjacent tissues surrounding the capillaries.     

Hemocyanin - antibody labeling of phodopsin in mouse retina for a scanning electron microscope study.

To reveal the presence of rhodopsin on the surface of the mouse retina, a scanning electron microscope study of the immunolabeling of rhodopsin was attempted. The glutaraldehyde-fixed mouse retina was treated first with rabbit antibodies specific against bovine rhodopsin and then with hemocyanin-labeled goat antibodies specific against rabbit antibody. The distribution of hemocyanin label on mouse retina and the technique used for labeling are discussed.     

A study of sparked aluminium samples with a scanning electron microscope and energy-dispersive X-ray analyser

A scanning electron microscope combined with an energy-dispersive X-ray spectrometer was used to investigate the erosion of the surfaces of aluminium samples after they have been exposed to single and multiple spark discharges in air and in argon. The erosion marks formed under the impact of an oscillating single spark discharge are different for the first and third current half-cycles, respectively, and are also dependent on the environmental gas. A uniform melt was formed at the centre of multiply sparked areas. The actual specimen becomes more inhomogeneous towards the perimeter of the sparked area.     

Measuring surface topography with scanning electron microscopy. I. EZEImage: a program to obtain 3D surface data.

Scanning electron microscopy (SEM) is widely used in the science of materials and different parameters were developed to characterize the surface roughness. In a previous work, we studied the surface topography with fractal dimension at low scale and two parameters at high scale by using the variogram, that is, variance vs. step log-log graph, of a SEM image. Those studies were carried out with the FERImage program, previously developed by us. To verify the previously accepted hypothesis by working with only an image, it is indispensable to have reliable three-dimensional (3D) surface data. In this work, a new program (EZEImage) to characterize 3D surface topography in SEM has been developed. It uses fast cross correlation and dynamic programming to obtain reliable dense height maps in a few seconds which can be displayed as an image where each gray level represents a height value. This image can be used for the FERImage program or any other software to obtain surface topography characteristics. EZEImage also generates anaglyph images as well as characterizes 3D surface topography by means of a parameter set to describe amplitude properties and three functional indices for characterizing bearing and fluid properties.     

Particle analysis for a strengthened safeguards system: Use of a scanning electron microscope equipped with EDXRF and WDXRF spectrometers

The purpose of this study was twofold: the identification of some uranium compounds and a measurement of mixed U/Pu particles with different ratios of these elements. We used a Philips XL-30 scanning electron microscope equipped with an EDAX energy dispersive spectrometer with a Si(Li) detector and a super ultra-thin polymer window and with a Microspec wavelength dispersive spectrometer. A number of WDXRF and EDXRF spectra of U and Pu containing particles were accumulated and evaluated. The software package provided by the manufacturer was used for EDXRF spectra evaluation and calculation of the weight and atomic composition. Eight different U compounds were identified with a different degree of confidence. Several different types of U and Pu particles were measured using the WDXRF spectrometer and the results of the measurements are discussed. The measurement of mixed U-Pu particles showing large differences in the concentration of both elements can best be carried out with the use of WDXRF because the deconvolution of the M lines of U and Pu in the energy dispersive spectra is only possible over a relatively small concentration range. The results of particle analysis are very useful for verifying the absence of undeclared nuclear activities.     

Cysteine adsorption on the Au(111) surface and the electron transfer in configuration of a scanning tunneling microscope: A quantum-chemical approach

Adsorption of two forms, molecule and radical, of amino acid L-cysteine (Cys) on the Au₁₂ cluster that simulates the (111) face of single-crystal gold is studied in the framework of the density functional theory. Effects of solvation of adsorbed Cys particles and lateral interaction in a monolayer are analyzed. The simulation predicts a commensurate adsorption energetics of the molecule and radical, with a difference between the “on-top,” “hollow,” and “bridge” positions. An analysis of lateral electrostatic interactions points to the stability of a cluster comprising six Cys particles, which conforms to the size of a fragment observed experimentally. Adsorption calculations are used to build three-dimensional isosurfaces (STM images), where the tungsten needle of the scanning tunneling microscope is simulated by a tungsten atom or by small clusters. The calculated images are sensitive to both the Cys shape and the orientation of adsorbed Cys particles. Calculation results are compared with fresh in situ submolecular-resolution STM data. Simulated images (with commensurate contributions made by sulfur atom and amino group) built for Cys radical adsorbed in the “on-top” position give best conformance to experiment.     

On the structure and stability of small metal particles: high-resolution UHV electron microscope study

Structures of gold clusters consisting of several to several tens of atoms and of small particles of 20–30 Å are seen by high-resolution UHV electron microscopy. The small particles have multiply twinned structures and show orientational fluctuation on a graphitized carbon substrate at room temperature, but no structural change from twinned to the fcc structure occurred during the observation with electron beam of 10–15 Amp/cm² on the specimen. Their structure changes at substrate temperature of 500°C. Small clusters show configurational change at room temperature from 5-fold arrangement to fcc one. These fluctuating motions are concluded to be due to thermal effect by estimating the temperature rise of the particles due to the electron beam to be less than 20–50°C from the melting temperature of lead particles.     

Reaction of SC+(1D,3D) with H2O, NH3, and CH4: a density functional study.

Density Functional Theory has been used to explore quantitative details of the potential energy hypersurface for the insertion reaction of scandium ion into the O-H, N-H, and C-H bond of water, ammonia, and methane molecules leading to H2 elimination. Both singlet and triplet state channels have been considered. On the basis of the obtained results, it is possible to conclude that for the molecules considered the reaction is a spin-forbidden process. Indeed, it starts in the triplet ground state and ends in the singlet state, the change of the spin state probably occurring immediately after the formation of the electrostatic complex intermediate.     

C D : a computer program to generate 1D, 2D and 3D grids of functions dependent on the molecular ab initio electron density

A program to compute many functions dependent on the electron density ρ(r) from the results of ab initio molecular calculations is presented. The program allows the generation of different one-, two-, and three-dimensional grids for further graphical representation or numerical analysis. Other options like extracting separate atom contributions to the function computed or locating maximum and minimum values are also implemented. A number of illustrative applications regarding different ρ(r)-dependent functions are presented and the performance and portability of the program is discussed.     

Epitaxial BaTiO3(100) films on Pt(100): a low-energy electron diffraction, scanning tunneling microscopy, and x-ray photoelectron spectroscopy study

The growth of epitaxial ultrathin BaTiO(3) films on a Pt(100) substrate has been studied by scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), and x-ray photoelectron spectroscopy (XPS). The films have been prepared by radio-frequency-assisted magnetron sputter deposition at room temperature and develop a long-range order upon annealing at 900 K in O(2). By adjusting the Ar and O(2) partial pressures of the sputter gas, the stoichiometry was tuned to match that of a BaTiO(3)(100) single crystal as determined by XPS. STM reveals the growth of continuous BaTiO(3) films with unit cell high islands on top. With LEED already for monolayer thicknesses, the formation of a BaTiO(3)(100)-(1 × 1) structure has been observed. Films of 2-3 unit cell thickness show a brilliant (1 × 1) LEED pattern for which an extended set of LEED I-V data has been acquired. At temperatures above 1050 K the BaTiO(3) thin film starts to decay by formation of vacancy islands. In addition (4 × 4) and (3 × 3) surface reconstructions develop upon prolonged heating.     

CHECKDEN: a computer program to generate 1D, 2D and 3D grids of functions dependent on the molecular ab initio electron density

A program to compute many functions dependent on the electron density rho(r) from the results of ab initio molecular calculations is presented. The program allows the generation of different one-, two-, and three-dimensional grids for further graphical representation or numerical analysis. Other options like extracting separate atom contributions to the function computed or locating maximum and minimum values are also implemented. A number of illustrative applications regarding different rho(r)-dependent functions are presented and the performance and portability of the program is discussed.     

Vibrational and scanning electron microscopy study of the mordenite modified by Mn, Co, Ni, Cu, Zn and Cd

The mordenite samples loaded with divalent nitrates of Mn, Co, Ni, Cu, Zn and Cd were investigated using FTIR and scanning electron microscopy (SEM) methods. It was found from FTIR spectra that in 3000-4000 cm⁻¹ region of mordenite samples with similar water concentration ions, Mn²⁺, Co²⁺, Cu²⁺, and Zn²⁺ tend to break hydrogen bonds formed between water molecules and zeolite framework, whereas Ni²⁺ and Cd²⁺ accommodate to hydrogen bonds. From SEM results it was concluded, that ions Mn²⁺, Co²⁺, Zn²⁺ form innersphere complexes with oxygens from Brönsted acid sites, whereas Ni²⁺ and Cd²⁺ associate with Brönsted acid sites without exchange of protons.     

A scanning electron microscopy study on hollow silica microspheres: defects and influences of the synthesis composition

Defects on hollow silica spheres synthesized in a tetraethylorthosilicate-octylamine-HCl-H₂O system were recorded by scanning microscope. Based on the results, influences of synthesis composition on the formation of these defects are discussed. It is evidenced that products prepared with different octylamine-to-tetraethylorthosilicate ratios may have surface depressions, cracks and non-hollow microspheres. However, by changing water and acid additions, these defects could be reduced or eliminated. Generally, samples synthesized with a large octylamine addition commonly exhibit surface depressions. A small octylamine or a large water addition benefits the formation of solid silica microspheres among the product. Acid, although is not indispensable for the formation of hollow spheres, helps to eliminate or reduce depressions on the hollow shells. It is explained that the added acid gives rise to a relative localized fast hydrolysis versus condensation, facilitating an easy mobility of hydrolyzed silica species, and consequently the shell surface is smoothened.     

CS families derived from the ReO3 structure type: An electron microscope study of reduced WO3 and related pseudobinary systems

A broad survey of some ReO₃-related CS structures has been carried out by means of an electron microscopy/diffraction study of the systems WO_x and (W⁶⁺, M⁵⁺O_x with M = V, Nb, Ta and 2.90 ? x < 3.00; MoO_x and (W, Mo)O_x; Nb(O,F)_x with 2.75 ? x ? 2.96; as well as V₂MoO₈. The observations give a broader view of the field than was previously possible. (i) They reveal the expected “swinging” of the CS planes when the compositions and/or the component ions are varied. (ii) They provide information on the degree of long-range order and the types of defect present. (iii) They throw further light on the likely mechanism by which the composition changes when a CS structure is reduced or oxidized. These topics are discussed, and an attempt is made to systematize all the observations into a coherent picture incorporating previously available information. This necessitates changing some earlier, dubious conclusions from X-ray diffraction studies.     

X-ray fluorescence (conventional and 3D) and scanning electron microscopy for the investigation of Portuguese polychrome glazed ceramics: Advances in the knowledge of the manufacturing techniques

This work shows the first analytical results obtained by X-Ray Fluorescence (XRF) (conventional and 3D) and Scanning Electron Microscopy with Energy Dispersive System (SEM-EDS) on original Portuguese ceramic pieces produced between the 16th and 18th centuries in Coimbra and Lisbon. Experts distinguished these productions based only on the color, texture and brightness, which originates mislabeling in some cases.Thanks to lateral and spatial resolution in the micrometer regime, the results obtained with μ-XRF were essential in determining the glaze and pigment thicknesses by monitoring the profile of the most abundant element in each “layer”. Furthermore, the dissemination of these elements throughout the glaze is different depending on the glaze composition, firing temperature and on the pigment itself. Hence, the crucial point of this investigation was to analyze and understand the interfaces color/glaze and glaze/ceramic support.Together with the XRF results, images captured by SEM and the corresponding semi-quantitative EDS data revealed different manufacturing processes used by the two production centers. Different capture modes were suitable to distinguish different crystals from the minerals that confer the color of the pigments used and to enhance the fact that some of them are very well spread through the glassy matrix, sustaining the theory of an evolved and careful procedure in the manufacturing process of the glaze.