bluuebunny/crossref_metadata_2025 huggingface dataset:
Two-Mirrors Model: Some Analytical Solutions for Generating the Constrained Coinsident-Site-Lattice and its Application to Bi2Sr2Ca1Cu2O8+δ Grain Boundaries
Authors: Volkov VV , Zhu Yimei
Published: July 2020

A knowledge of grain boundaries (GBs) and interfaces is essential in establishing the relationship between the structural details of the boundaries and the strength of superconducting coupling and critical current densities at the boundaries in textured Bi cuprates. As a step towards such understanding, we studied GB crystallography and lattice mismatch using the constrained Coincidence-Site-Lattice (cCSL) theory. We note that to characterize arbitrary GBs in a complex system such as Bi2212, it would be desirable to find some simple analytical solutions for the cCSL approach.

We report our new concept of a “two-mirrors” model (2M-model), which allow us, in principle, to find sufficient conditions to generate corresponding analytical solutions for CSL (or cCSL), when it is applied to crystals with cubic, hexagonal, or orthorhombic symmetry. The 2M-model is based on the fact that any boundary can be described by rotating one crystal relative to the other along a common axis.
Application Of Field-Emission Tem To Investigating Flux Pinning Mechanism In Superconductors
Authors: Tonomura Akira
Published: July 2020

Magnetic vortices in superconductors have become directly and dynamically observable[l] by Lorentz microscopy in our 300 kV field-emission TEM[2]. Since material defects can also be observed simultaneously though the images are defocused, the microscopic flux pinning mechanism can be directly observed. Using this technique, we observed when and how vortices trapped at artificial defects were depinned.

Artificial point defects were produced by the irradiation of a focused Ga ion beam. Electron microscopy revealed that the defect consisted of a pit 300 Å in radius surrounded by entangled dislocations. The depth of a pit increased with the ion dose.

We first investigated the pinning force of individual defect: by observing the depinning of vortices from defects produced with various ion-doses. When a force was exerted on vortices trapped at the defects by changing the magnetic field and increased, we found that the pinning force of defects increased with the ion doses.
Observation and Theoretical Prediction of Structure in Amorphous Carbon and Related Materials
Authors: McKenzie DR , McCulloch DG , Goringe CM , Merchant AR
Published: July 2020

Covalently bonded materials of the light elements B, C, N, O and Al form an interesting series of structures which are readily prepared by physical vapour deposition methods. The most important structural issues are the degree of positional order (that is, whether the material is amorphous or nano phase crystalline) and for alloys, the degree of site occupancy order (that is, the extent of ‘chemical’ order). We propose that the degree of positional order is dependent on the bond angle stiffness of the covalent bonding and the degree of chemical order is dependent on the energy difference of bonds between like and unlike atoms (see figure 1).

The observation of structure in these materials is conveniently carried out by electron optical techniques in an electron microscope. The techniques of value are (a) Energy Filtered Electron Diffraction, and (b) Electron Energy Loss Spectroscopy (EELS).
Silicon Carbide Amorphization by Electron Irradiation
Authors: Bentley J
Published: July 2020

Observations made more than ten years ago1 showed that SiC could be made amorphous at cryogenic temperatures by in-situ 300kV electron irradiation. However, high-voltage electron microscope (HVEM) results indicate a threshold voltage of 725 kV for amorphization of SiC at 140 K. In addition, a recent review exposes the considerable uncertainty in the literature regarding displacement energies for SiC. Therefore, further experiments have been performed in a Philips CM30 (LaB6 cathode) with a Gatan double-tilt cooling holder in an attempt to determine the threshold voltage for amorphization at ∼ 140 K. Sintered α-SiC (defected 6H polytype), beam direction B=< 1120 >, and probes containing ∽ 75 nA in ∽0.5 μm, were used. Amorphization occurred in <10 min at 300 kV and after ∽60 min at 180 kV (Fig. 1); visible darkening occurred at lower voltages and doses. Similar behavior occurred for B=[0001]. The critical dose for amorphization was measured as a function of accelerating voltage.
RDF Analysis of Radiation-Amorphized SiC using a field Emission Scanning Electron Microscope
Authors: Bell David C , Garratt-Reed Anthony J , Hobbs Linn W
Published: July 2020

Abstract

Fast electrons are a particularly useful chemical and structural probe for the small sample volumes associated with ion- or fast electron-irradiation-induced amorphization, because of their much stronger interaction with matter than for X-rays or neutrons, and also because they can be readily focused to small probes. Three derivative signals are particularly rich in information: the angular distribution of scattered electrons (which is utilized in both diffraction and imaging studies); the energy loss spectrum of scattered electrons (electron energy loss spectroscopy, or EELS); and the emission spectrum of characteristic X-rays resulting from ionization energy losses (energy dispersive X-ray spectroscopy, or EDXS). We have applied the first two to the study of three amorphized compounds (AIPO4, SiO2, SiC) using MIT's Vacuum Generators HB603 field-emission (FEG) scanning transmission electron microscope (STEM), operating at 250 kV and equipped with a Gatan digital parallel-detection electron energy-loss spectrometer (digiPEELS).
Microstructure in Nanophase and Amorphous Boron-Based Thin Films
Authors: Medlin DL , McCarty KF , Buchenauer DA , Dibble D , Poker DB
Published: July 2020

Boron-based thin film materials have numerous uses ranging from application as hard and refractory protective coatings to potential employment in wide-band gap semiconductor electronics. Of particular interest are the boron carbides, nitrides, oxides, and phosphides. These compounds exhibit a broad range of structural and bonding variations. The crystalline form of elemental boron is based on an arrangement of 12-atom boron icosahedra positioned at the vertices of a rhombohedral lattice. Related materials, such as B4C, and B12P, also possess structures closely related to this icosahedrally coordinated prototype. However, the structural coordination of the boron carbides and phosphides will vary with composition. For instance, BP possesses a tetrahedrally coordinated zinc-blende structure, and the carbon-rich boron carbides will form in a graphitic structure. Boron nitride has the added complication that for the same composition (BN) multiple bonding and polytypic variations are possible: both soft, graphitic sp2-rich (e.g., hexagonal and rhombohedral BN) and hard, diamond-like sp3-rich phases (e.g., cubic and wurtzitic BN) can be formed.
Studies of Hexagonal Pt and Au Nanocluster Superlattices
Authors: Newcomer Provencio P , Martin J E , Odinek J G , Wilcoxon J P
Published: July 2020

We have recently synthesized superlattices of Pt and Au nanoclusters grown by inverse micelle techniques. The monodisperse nanosize metal clusters used in this study were synthesized as surfactant aggregates surrounded by an oil-like environment (inverse micelle), a technique developed and patented at Sandia. Reaction byproducts, such as excess surfactant and inorganic ion salts, are often separated from the metal clusters using liquid chromatography size exclusion techniques; however, the Pt and Au nanoclusters in this study have been fractionated using a liquid-liquid technique. The nanoclusters are capped with a ligand.

Two-dimensional hexagonal arrays formed readily on surfaces, and large twinned three-dimensional crystals form from solution. Both the cluster size and the size of the capping ligand can be controlled to form superlattices having a range of lattice parameters. We have found that the capping agent exerts a marked influence on the tendency of these clusters to order.
Self-Assembled Cobalt Oxide Nanocrystals with Tetrahedral Shape
Authors: Yin JS , Wang ZL
Published: July 2020

Nanocrystal materials are an emerging research field of chemistry, physics and materials science. The size and shape specificity of nanocrystals suggests them as building blocks for constructing selfassembly passivated nanocrystals superlattices (NCS's) or nanocrystals arrays (NCA) [1-6]. In this paper, NCAs of CoO with controlled tetrahedral shape are reported and their structural stability is examined by in-situ TEM.

Cobalt oxide nanocrystals were synthesized by chemical decomposition of Co2(CO)8 in toluene under oxygen atmosphere, as given in detail elsewhere [1].Sodium bis(2-ethylhexyl) sulfosuccinate (Na(AOT)) was added as a surface active agent, forming an ordered monolayer passivation (called the thiolate) over the nanocrystal surface. The particle size was controlled by adjusting the wt.% ratio between the precursor and Na(AOT). The as-prepared solution contained Co, CoO and possibly C03O4 nanoparticles, and pure CoO nanoparticles were separated by applying a small magnetic field, which is generated by a horseshoe permanent magnet in vertical direction.
Monalayer Arrangement of Pt Nanoparticles
Authors: Green T C , Petroski J M , Wang Z , El-Sayed M
Published: July 2020

Formation of metallic nanoparticles produces an increased surface area per unit volume of material, which provides potential applications in enhancing surface catalyzed reactions. Recently, attention has been focused on moving from the solution based syntheses to solid phase materials by arranging such particles into well ordered 2- and 3- dimensional structures, or forming cluster engineered materials that posses well defined structures. Such studies have shown the importance of size, size distribution, and shape of particles upon self assembled monolayers. We have recently prepared shape-controlled Pt nanoparticles with ﹛111﹜ (tetrahedral), ﹛100﹜ (cubic), and mixed ﹛111﹜ - ﹛100﹜ (truncated octahedral) faces. To study how these faces may orient to form particle point superlattice structures we have prepared monolayer distributions of Pt particles in humidity chambers for analysis by TEM.

Our shape controlled Pt particle synthesis yields between 60 and 80 % cubes, tetrahedra, or truncated octahedra with average diameters ≥ 7 nm.
Nano-Characterization of Industrial Heterogeneous Catalysts
Authors: Liu J , Ebner JR
Published: July 2020

Catalyst characterization plays a vital role in new catalyst development and in troubleshooting of commercially catalyzed processes. The ultimate goal of catalyst characterization is to understand the structure-property relationships associated with the active components and supports. Among many characterization techniques, only electron microscopy and associated analytical techniques can provide local information about the structure, chemistry, morphology, and electronic properties of industrial heterogeneous catalysts. Three types of electron microscopes are usually used for characterizing industrial supported catalysts: 1) scanning electron microscope (SEM), 2) scanning transmission electron microscope (STEM), and 3) transmission electron microscope (TEM). Each type of microscope has its unique capabilities. However, the integration of all electron microscopic techniques has proved invaluable for extracting useful information about the structure and the performance of industrial catalysts.

Commercial catalysts usually have a high surface area with complex geometric structures to enable reacting gases or fluids to access as much of the active surface of the catalyst as possible.
In Situ Oxidation and Reduction of Small Pd Particles on Silica
Authors: Crozier Peter A , Sharma Renu
Published: July 2020

Palladium based catalyst have technological applications in catalytic converters in automobile industry for the combustion of NOx and CO gasses. Pd can also adsorb up to 900 times its volume H2 and is useful for purifying H2. Electron holography studies with model Pd on silica catalysts [1] show that under some circumstances, the Pd particles may form voids. The reason for the formation of these voids and the conditions under which they are formed are not well understood. We have done in situ and ex situ studies on oxidation and reduction of similar model Pd/SiO2 to develop a better understanding of the conditions under which voids are formed.

The catalyst samples were prepared by impregnating silica with acetyl acetoneate (acac) and oxidizing in air and then reducing in H2 at 300°C [1]. High resolution images (Fig. 1) of Pd particles show a central feature with low contrast attributed to the presence of voids.
Electron Holography and Digital Imaging for Analysis of Nanostructured Materials
Authors: Allard L F , Voelkl E , Datye A K , Carim A H
Published: July 2020

Many nanostructured materials are formed from powder precursors having ultra-fine particle sizes. Techniques of electron microscopy have proven invaluable for characterizing the structure of the precursor materials in order to better understand the fundamental processes that govern consolidation of the materials into the final nanophase structures. In recent years, the rapidly developing technique of electron holography has increasingly been applied for characterizing particle morphologies. The advent of the modern field emission microscope, which offers beam coherency sufficient to produce high contrast interference fringes for optimum hologram formation, and especially the availability of digital camera systems for hologram acquisition and rapid processing have both combined to bring electron holography to the forefront of techniques for characterization of nanostructured materials.

Electron holograms typically yield phase images that can give quantitative information on crystal morphologies, but much additional information can result from digital processing of holograms.
Atomic Structure of Interfaces: Link of Atomistic Calculations with High Resolution Electron Microscopy
Authors: Vitek V
Published: July 2020

Since interfaces and grain boundaries affect critically many properties of materials, their atomic structure has been investigated very extensively using computer modeling. Most of these calculations have been made using semi-empirical central-force descriptions of atomic interactions, recently primarily the embedded-atom type many-body potentials. Owing to the approximate nature of such schemes, a connection with experimental observations that can validate the calculations is essential. The high resolution electron microscopy (HREM) is such experimental technique and it has, indeed, been frequently combined with calculations of interfacial structure and chemistry. In fact such a link is not only important for verification of the results of computer modeling but also crucial for meaningful interpretation of HREM observations. Hence, coupling the atomistic modeling with HREM is a synergistic procedure. It not only leads to better understanding of interfacial structures but may contribute significantly to the validation and assessment of limits of the schemes used for the description of atomic interactions.
Monte Carlo Simulation of Solute-Atom Segregation at Grain Boundaries In Single-Phase Binary Face-Centered Cubic Alloys
Authors: Seidman David N , Rittner John D , Udler Dmitry
Published: July 2020

Solute-atom segregation to grain boundaries has been of interest since the 1930's when it was realized that some steels were susceptible to failure by intergranular fracture when certain impurities were present. Segregation of impurities or intentionally added alloying elements at grain boundaries can greatly affect various grain boundary properties, which in turn affect numerous macroscopic properties. Materials phenomena that have been linked to grain boundary segregation include temper brittleness, fatigue strength, adhesion, precipitation, diffusional creep, intergranular corrosion, and grain boundary diffusivity. Although grain boundary segregation has been extensively studied for many years, the effects of different grain boundary structures on segregation was generally not considered. It has been established both experimentally and theoretically that the level of segregation varies from grain boundary to grain boundary in the same alloy, but there is little direct information on how grain boundary structure influences segregation.
Investigating Atomic Scale Structure-property Relationships at Grain Boundaries
Authors: Browning N D , Moltaji H O , James E M , Stemmer S , Buban J P , Zaborac J
Published: July 2020

Although grain boundaries are known to dominate the bulk properties of many technologically important materials, in most cases there is no fundamental atomic scale understanding of why they should have such an effect. One of the problems in developing this understanding is that conventional structure determination techniques, such as phase contrast imaging in TEM or Z-contrast imaging in STEM, produce only a 2-dimensional projection of the crystal structure. Atomic scale compositional changes must be simulated and a unique interpretation is clouded by boundary reconstructions and strain effects. Furthermore, neither technique provides any information on the local changes in the electronic structure that are critical for both the electrical and mechanical properties of the boundary.

EELS provides a means to quantify local changes in both composition and electronic structure. However, without a knowledge of the structure, interpretation of any observed changes at grain boundaries is extremely difficult.
Microstructure of Josephson Junctions: Effect on Supercurrent Transport in YBCO Grain Boundary and Barrier Layer Junctions
Authors: Merkle K L , Huang Y
Published: July 2020

The electric transport of high-temperature superconductors, such as YBa2Cu307-x (YBCO), can be strongly restricted by the presence of high-angle grain boundaries (GB). This weak-link behavior is governed by the macroscopic GB geometry and the microscopic grain boundary structure and composition at the atomic level. Whereas grain boundaries present a considerable impediment to high current applications of high Tc materials, there is considerable commercial interest in exploiting the weak-link-nature of grain boundaries for the design of microelectronic devices, such as superconducting quantum interference devices (SQUIDs). The Josephson junctions which form the basis of this technology can also be formed by introducing artifical barriers into the superconductor. We have examined both types of Josephson junctions by EM techniques in an effort to understand the connection between microstructure/chemistry and electrical transport properties. This knowledge is a valuable resource for the design and production of improved devices.
Field Emission Scanning Electron Microscopy Studies of Industrial Polymers - A Survey
Authors: Osten EF , Smith MS
Published: July 2020

We are using the term "Industrial Polymers" to refer to polymers [plastics] that are produced by the ton or (in the case of films) by the mile. For example, in descending order of world-wide use (tonnage), the top eight of these polymers are polyethylene (PE), polyvinyl chloride (PVC), polypropylene (PP), styrene polymers (including polystyrene - PS, and acrylonitrile-butadienestyrene/ styrene-acrylonitrile - ABS/SAN), polyesters (PETP), polyurethane (PU), phenolics and aminoplastics.

Industrial polymers, which have been produced by the millions of tons for the last five decades and are of obvious social and economic importance, have been exhaustively characterized. Structural features which affect physical properties and indicate process variables have been studied by many techniques other than microscopy (x-ray diffraction, thermal analysis, rheology, chromatographies, etc.). Microscopy techniques for polymer characterization have been well documented. Our motivation to apply field emission (high resolution) scanning electron microscopy to the study of polymers is: (1) The application of low voltage, high resolution SEM to biological materials is well characterized.
Tem Studies of Single and Double Microdomain Layers of Block Copolymer
Authors: Yao N , Park M , Harrison C , Adamson D H , Chaikin P M , Register R A
Published: July 2020

Diblock copolymers consist of two chemically different polymer chains (or blocks) joined by a covalent bond. Because of the incompatibility between the two blocks and connectivity constraints, diblock copolymers spontaneously self-assemble into microphase-separated nanometer size domains that exhibit ordered morphologies at equilibrium. Commonly observed microdomain morphologies in bulk samples are periodic arrangements of lamellae, cylinders, and spheres. Recent studies show that the thin films of such block copolymers are of great potential for many nanoapplications including nanolithography and template synthesis for inorganic materials. Here, we report TEM studies of osmylated and ozonated thin diblock copolymer films.

An asymmetric block copolymer was synthesized with a composition of 36 kg/mol for the poly(styrene)(PS) block and 11 kg/mole for the poly (butadiene)(PB) block such that the microphase separation produces PB cylinders in a matrix of PS. The films were spin-coated from solution onto thin silicon nitride windows and annealed above the glass transition temperature in vacuum.
In Situ Tem Study of Inert Fillers in Liquid Environment
Authors: Chiou W-A , Lee Y-C , Ishikawa A , Konishi H , Fukushima K , Shriver D F
Published: July 2020

Polymer electrolytes are a topic of interest because of their potential applications in electrochemical devices. However, very few systems exhibit both high conductivities and mechanical strength. Composite polymer electrolytes, composed of conventional polymer electrolytes and inert fillers, provide an avenue to enhance mechanical strength while maintaining ionic conductivity, if the particle sizes of these inert fillers are sufficiently small (< 1 μm in diameter). The determination of the morphology for these inert fillers in polymer matrixes was undertaken to further our understanding of ion transport phenomena in these composite systems. This paper presents an in situobservation of inert fillers in liquid media using environmental TEM.

Surface-modified fume silica was prepared by a two-step process. (1) SiCl4 was used to activate surface silanol (SiOH) groups and generate reactive SiCl groups on the surface of fume silica particles (Aldrich, 7 nm in diameter).
Scanned-Probe Microscopy of Elastomer Blends: Morphology and Mechanical Properties
Authors: Mallamaci Michael P
Published: July 2020

Scanned-probe microscopy (SPM) has found application to a variety of polymer systems, primarily for the examination of surface morphology and the assessment of surface properties. In fact, SPM is unique in its ability to probe both phase morphology and mechanical properties simultaneously. The examination of industrial elastomers and their blends by SPM techniques can provide morphological information historically obtained only by transmission-electron microscopy (TEM). Since contrast with the SPM can be generated by differences in mechanical response of the constituent phases, polymer blends which are difficult to etch or stain for TEM can be successfully examined. In many cases measurements of polymer morphology can be made more easily with SPM, since time-consuming steps associated with thin-section production and staining are not required. Contact and tapping-mode operation along with force modulation and phase measurement can be used to examine phase microstructure, phase morphology, filler type, filler distribution, and viscoelastic response in elastomer systems.
Morphology of Silicone/Organic Blends
Authors: Zhang Hongxi , Chen Wei
Published: July 2020

Silicone materials may be incorporated into organic thermoplastic resins to provide enhanced properties. Good dispersion of silicone with plastics is believed to be one of the keys to control the applications of these multiphase blends. In this study, we investigated the morphologies of mechanically mixed silicone/organic blends using scanning electron microscopy (SEM). Results provide an important piece of information that the optimum silicone phase dispersion can be achieved by matching the viscosities of the blend components.

Most silicone and organic polymers are thermodynamically immiscible, forming multiphase structures for their blends. For example, a blend consisting of 90 wt% polydimethylsiloxane (PDMS) and 10% low density polyethylene (LDPE) was revealed by SEM to have a multiphase structure shown in Figure 1A where the PDMS was a Dow Corning® 3-5016 silanol-terminated siloxane fluid that forms the dispersed phase and the LDPE a Dow Chemical polyethylene having a melt index of 4.
Scanning Electron Micrsocopy of Various Natural Textile Fibers
Authors: Buschle-Diller Gisela
Published: July 2020

Plant fibers such as cotton, hemp and flax have been cultivated for textile purposes for thousands of years. These natural fibers play an important role in daily life as apparel fibers since they provide unique comfort properties unsurpassed by synthetic fibers. However, their use is not limited to the apparel sector. In recent years the market share of consumer textiles and industrial products made from all kinds of natural fibers has tremendously increased as they present a valuable source of renewable raw materials. Investigating their surface features by microscopic techniques is important to control the performance of the desired end-product. Processing steps involving heat, light or exposure to chemicals might have a significant impact on the specific surface properties of a fiber whether or not this was originally intended. Scanning electron microscopy is therefore a very useful tool for the characterization of textile products to determine the effectiveness and eventual resulting damage from physical or chemical treatments.
Automating Analysis of Fibrous Materials
Authors: Bresee Randall R , Yan Zanyao
Published: July 2020

Natural fibers generally lack uniformity and large numbers of measurements often must be obtained to achieve estimates of sample parameters having reasonable levels of precision and confidence. This problem calls for automating the measurement and data analysis processes so obtaining a large amount of data is practical. We will discuss hardware and software designs used in our laboratory to automate microscope measurements and data analysis for fibrous materials.

Automating the measuring process requires constructing hardware to accomplish several tasks. Hardware should accommodate large-sized samples when they lack uniformity since many measurements are desirable. Sample positioning should be automated to remove the operator from the data acquisition process and eliminate a source of operator-dependent positioning error. Lens focusing should be automated since it is difficult to maintain flatness for large samples and the thickness of many samples exceeds the depth-of-focus of lenses. Finally, the quality of illumination provided to all sample locations during measurement should be flexible and consistent.
Microscopic Examination of Native and Modified Cotton Fibers
Authors: Goynes Wilton R
Published: July 2020

Cotton is the single most economically important natural textile fiber in the world. It is a seed hair and has historically composed a large portion of the world's textiles. The plant is grown in most tropical and subtropical regions of the world. The demand for cotton, especially as a garment fiber, it due to properties such as its soft hand, water absorption, spinnability, and dyeability, and to its ease of home laundering. Perhaps cotton's most important textile property is its comfort. These properties are due to the unique, multilayered construction of the fiber subunits. The nature of this construction has been studied microscopically for more than 100 years, first using light microscopes, then electron microscopes as they became available. Because they are natural biological materials, no two cotton fibers are exactly alike. Yet they do have certain structural features in common. Structure in cotton can refer to several levels of construction.
An En Bloc Staining Protocol Improves The Preservation of Lamellar Bodies in Alveolar Type II Epithelial Cells for Transgenic Mice Expressing Modified Pulmonary Surfactant Protein B
Authors: Na C-L , Beck D C , Breslin J S , Wert S E , Weaver T E
Published: July 2020

The extraction of lipids and phospholipids during dehydration and plastic embedding steps results in poor preservation of the phospholipid rich lamellar bodies (LB) in alveolar type II epithelial cells. To achieve better retention of phospholipids, we combined inflation fixation and an en bloc staining protocol using 4% aqueous uranyl acetate (UA), thereby improving the preservation of the LBs for both the wild type and transgenic mice expressing modified pulmonary surfactant protein B (SP-B; Akinbi et al., 1997).

Lungs of 6-8 week-old mice were inflation fixed (Bunkingham and Weyder, 1981) with ice cold 2% paraformaldehye and 2% glutaraldehyde in 0.1 M sodium cacodylate buffer (SCB), pH 7.3, postfixed in fresh fixative at 4 °C overnight, incubated with 1% osmium tetroxide in 0.1 M SCB at room temperature for 2 hours, and stained en bloc with 4% aqueous UA overnight.
Cross-Section Tem Sample Preparation for Copper / Low-K Composite Stacks by Ion Milling
Authors: Foran B , Shaapur F , Blaschke V
Published: July 2020

Sample preparation for transmission electron microscopy (TEM) has been a source of speculation with regards to potential for the creation of artifacts which may confound data gleaned from TEM analysis. For semiconductor integrated circuit (IC) materials characterization, the most common sample preparatory methods are based on final thinning by ion beam milling. The latest shift towards Copper / low dielectric constant (k) composite systems in the semiconductor IC industry provides several challenges for TEM sample preparation resulting from differences in milling rates and materials properties for neighboring features.

In conjunction with process development for integration of Cu / low-k materials, conducted at SEMATECH, we have systematically studied the effects of TEM sample preparation by ion milling in order to search for artifacts that could result from sample thinning procedures. For this purpose we have studied wafers with patterned copper lines isolated by a low-k polymer. One sample was stressed by thermal and electronic bias, while a second was subjected to only thermal stress.
A new approach for Cross-Sectioning Sem Specimens of Semiconductors by Broad-Ion Beam Milling
Authors: Ogura K , Alani R
Published: July 2020

The cross-sectioning of semiconductor wafers for SEM studies has traditionally been carried out by tedious and laborious mechanical grinding and polishing techniques. The mechanically polished surfaces are treated using a “wet chemical” etching method to enhance and delineate certain features or layers in a given specimen. The etched specimens are then coated by conductive layers to prevent charging during SEM examination. As an alternative to “wet chemical etching”, broad-ion beam etching techniques have been developed for surface treatment of mechanically polished specimens. More specifically, we have reported [1] the utilization of a combined process of broad-ion beam etching and coating of mechanically cross sectioned semiconductors in a single vacuum chamber. As a further progress to that work, we report a rapid and reliable technique for preparing precision SEM cross sections. The technique is based on perpendicular broad-ion beam milling of cleaved wafers to expose any desired cross-section through a given feature of the specimen.
Preparation of thin Sections of (znxcdy)s Fine Particles by an Ultramicrotome
Authors: Ahn S H , Park G S , Ahn N R
Published: July 2020

The low voltage phosphors should be efficiently excited with an electron beam value lower than 500V. Thus the properties of low voltage phosphors are directly affected by the surface states of phosphors. Recently, to improve the properties of these phosphors, much analysis has been carried out focused on the surfaces of phosphors using by FESEM, AES or XPS etc.. Nevertheless, the microstructure of phosphors around the surface has not been made clear due to the resolution limits of the above equipments and the difficulties of sample preparation. In this study, in order to analyze the microstructure of phosphors around the surface, we have prepared the thin sections of the (ZnxCdy)S phosphors by an ultramicrotome and carried out high resolution electron microscope(HREM) study on the thin sections.

To carry out ultramicrotomy, the particles of phophors were embedded with acrylic resin (methyl methacrylate: n-butyl methacrylate= 4:6, Benzoyl peroxide 1.5%) in a capsule.
Tem Specimen Preparation for Display Materials of Vacuum Fluorescent Displays
Authors: Dolukhanyan T , Sung C , Ahn S , Lee J
Published: July 2020

Further development of Vacuum Fluorescent Displays (Fig.l) for low cost production and high yield requires investigation of all the components on a submicron scale at various processing stages.

A variety of specimen preparation methods have been used for making different types of high quality cross-sectional and plan-view TEM specimens from:

1. Initial phosphor materials - ZnCdS powders admixed with conducting powder of ln2O3; 2. In2O3 mixed ZnCdS phosphor layers of ready-made working VFD; 3. W - filament cathodes coated with (Ba,Sr,Ca) oxides. Rapid sharing of results.

Group 1 specimens were made both by direct dispersion of phosphor powder particles on the carbon coated copper grid from acetone diluted powder suspension, and by preparation of cured bulk material from the powder using Gatan G-l epoxy, followed by cutting, grinding-dimpling and final ion milling in Gatan DuoMill 600 (Fig.2).
Plasma Cleaning for Electron Microscopy
Authors: Isabell Thomas C , Fischione Paul E
Published: July 2020

Specimen contamination and amorphous irradiation damage severely limit the ability to perform accurate electron microscope analysis of materials, especially as specimen areas of interest decrease in size. To analyze smaller areas of interest, electron probe sizes have decreased, while probe currents have increased. The combination of these two factors results in an increase in the amount of carbonaceous contamination formed on the specimen under the electron beam. Recently, the use of low energy plasmas has been shown to be effective in preventing such contamination from occurring (1-3). For TEM, the simultaneous placement of the specimen holder and specimen into such a plasma for short periods of time (usually less than two minutes) results in the ability to hold a converged probe on the specimen for analysis without contamination becoming an problem. Figure 1 is a TEM micrograph of a 304 stainless steel specimen.
AFM and Other Scanned Probe Microscopies Tutorial
Authors: Russell Phillip E , Batchelor A D
Published: July 2020

While the techniques offer high spatial resolution in some cases down to the atomic scale and three dimensional mapping of surface topography, there still remain issues related to quantitative interpretation of scanned probe data, particularly in the recently developed phase contrast imaging modes. In this talk, the various modes of force microscopy will be introduced, along with examples. New techniques are starting to emerge which allow us to use the scanned probe microscope to measure properties such as local adhesion and local elastic and plastic deformation of samples.

Each scanned probe technique relies on a very sharp probe positioned within a few nanometers of the surface of interest. Some combination of probe and/or substrate positioning is required to provide sub-nm-resolution, three-dimensional motion of the probe relative to the substrate. When the probe translates laterally (horizontally) relative to the sample, any change in the height of the surface causes the detected probe signal to change.
Convolution and Deconvolution For 3D Imaging Of Cell Physiology
Authors: Loew Leslie M , Sapia Mark , Schaff James
Published: July 2020

Fluorescence intensity in a spectrofluorometer is proportional to the concentration of analyte over a wide dynamic range and is, therefore, an excellent quantitative analytical tool. In this paper we use the techniques of deconvolution and convolution to extend the utility of quantitative fluorescence to the measurement of analyte concentrations inside cells and their organelles. This permits us to assess the physiological state of living cells in situ.

To successfully turn a voxel within a 3D image into a microcuvette, 2 conditions must be met. First, to be sure the voxel is associated with only one fluorescent structure, the object that is being measured must be fully resolved from neighboring objects in all three dimensions. For structures separated by distances larger than about 300nm in the xy plane or 600nm in z (where z is the optical axis), this can be achieved with either digital deconvolution of 3D widefield images or by confocal microscopy.
Nanobiotechnology: Biological Applications of Nanofabrication
Authors: Turner JN , Shain W , Szarowski DH , Kam L , Craighead HC , Isaacson M , Turner S , Davis R , James C , Banker G
Published: July 2020

Nanobiotechnology is the fusion of biology and nanofabrication (Hoch, et al. 1996). Nanofabricated devices are increasingly being used in biological studies, and surface modification methods are important for interfacing inorganic devices with tissues.

Nanofabricated implants are used to study brain physiology (Najafi and Wise, 1986). These implants can have cross-sectional dimensions as small as 15 μm. However, the implants cause glial scars that inhibit their operation. Figure 1 shows a model implant, with a trapezoidal cross section (base=200 μm, height=130 μm, top=60 μm, length=2 mm), for studying scar formation. Implants were inserted into the brains of rats and tissue was harvested after 1 hr. to 12 wks. Figure 2 shows a thick (100 μm) section of brain prepared 7 days after implantation; the section was immunolabeled for glial fibrillary acidic protein (GFAP) and imaged in a Bio-Rad confocal microscope. The implantation site is surrounded by GFAP positive material indicative of reactive astrocytes.
Choosing a Scanning Electron Microscope
Authors: Lambe W A , Brady PM
Published: July 2020

The variety of instrumentation available to the researcher today can be overwhelming and confusing. Scanning Electron Microscopes (“SEM's) are no exception, and choosing one can often serve as an exercise in dealing with complexity. First time purchasers are most at risk, being subject to a barrage of information that attempts to sway the purchaser in one direction or the other. As a result, one can sometimes be drawn to the details of the latest “high end” performance parameter, while overlooking the basics. At its worst, the selection process can degrade to one of vague guesswork with little hard data to serve as a compass.

By applying a methodical approach to define your individual requirements, carefully designed tests of actual instruments, and discussions with your collaborators, potential and experienced users, one can begin to ensure a successful selection process.
Choosing a Suitable Ultramicrotome, Associated Equipment and the Proper Laboratory Environment for Operation of the System
Authors: Bozzola John J
Published: July 2020

The selection of an ultramicrotome should always begin with an evaluation of the immediate as well as the long-term needs of the laboratory. If present projects require ultramicrotomy on a regular basis (e.g., more than 5-10 specimens per week) and if this demand will probably continue for more than one year, the acquisition of an ultramicrotome is justified. An intensive, short-term project or an occasional need with no clear indication of a future requirement for ultramicrotomy could best be accommodated by either leasing an ultramicrotome or contracting the work to an individual or corporation. On the other hand, several laboratories with modest needs may wish to pool resources and purchase a shared instrument capable of fulfilling the requirements of each lab.

Since new ultramicrotomes cost $20k and up, one may be compelled to acquire a used instrument. Depending upon the age and condition, a used ultramicrotome may be purchased at a cost of $2-15k.
Current Applications and Methods of Microvascular Corrosion Casting: A Review
Authors: Lametschwandtner A , Aichhorn H , Minnich B
Published: July 2020

Casting of hollow spaces with solidifying materials and subsequent removal of surrounding tissues by corrosive alkali and acids and the inspection of the remaining casts by bare eyes or the dissecting microscope is an old anatomical technique.

The introduction of polymerizing resins as casting materials which resulted in durable casts of even the smallest spaces (bile and blood capillaries) and the application of the scanning electron microscope with its high resolution and great depth of focus, enabled the qualitative and the quantitative analysis of the 3D-arrangement of tubular systems by means of their casts.

Presently, scanning electron microscopy of microvascular corrosion casts is used to study growing, stable or regressing blood vessel systems under physiological (e.g. during development, wound healing, metamorphosis) and pathological (e.g. tumor angiogenesis) conditions in qualitative and quantitative terms.
Vascular Corrosion Casting: Physiological Considerations
Authors: Olson KR
Published: July 2020

Vascular corrosion replicas provide unique three-dimensional models of both macro- and microcirculatory angio-architecture. In most replication procedures, blood is initially flushed from the vasculature with a low viscosity, noclotting medium, such as saline, prior to infusion with the unpolymerized resin. While this removes cellular elements from the vessels and also prevents coagulation, the chemical characteristics of the saline and the mode in which it is infused can affect the vasculature. This can be disadvantageous if subsequent distribution of the resin does not faithfully mimic normal perfusion pathways, or if the vascular lumen is either narrowed due to vasospasm or distended due to excessive intravascular pressure. Alternatively, the composition of the saline can be modified to enhance the replication process. This may be done merely to ensure complete filling of the vasculature or to evaluate anatomical foci instrumental in physiological and pharmacological regulation of perfusion distribution.
Corrosion Cast Demonstration of Tongue Vasculature of Normal Wistar Rats
Authors: Makiyama M C K , Watanabe I , Chopard RP , Iyomasa M M , Mizusaki C I , Lopes RA
Published: July 2020

The purpose of this study has been to undertake a three-dimensional analysis of the vascular network of the lamina propria in the lingual mucosa of the rat. Using the corrosive-resin casting method, casts of the vascular network were prepared and examined by scanning electron microscopy. We used 21th day normal wistar rats. They were anesthetized and perfused with saline solution and after with mercox (25ml of resin, 5ml of methyl methacrylate monomer). Then, the tongues were resected and placed in warm water bath at 60° C for 4 h. The tongue epithelium were digested with 20% NaOH for 4 days. The vascular resin casts washed in distilled water, several times. The dried vascular casts were mounted on the stubs with conductive paste, coated with gold and examined with a JEOL JSM- 6100 scanning electron microscope. In the SEM images, the lingual mucosa revealed arteriolae which divide into smaller branches entering into connective tissue papillae.
Shear and Substrate Dependent Changes in Fibrinogen and Von Willebrand Factor Studied by Atomic Force Microscopy
Authors: Marchant Roger E , Sidney Sit P , Raghavachari Madhusudan , Siedlecki Christopher A
Published: July 2020

Atomic force microscopy (AFM) provides unique opportunities to study cell-surface and molecular scale interactions in three dimensions under aqueous conditions. Two plasma proteins, von Willebrand Factor (vWf) and fibrinogen, play central roles in the regulation of hemostasis and thrombosis by participating in coagulation and facilitating adhesion and aggregation of activated platelets. vWf and fibrinogen are believed to facilitate platelet adhesion under regions of relatively high and low vascular wall shear stress, respectively. Consequently, elucidating vWf and fibrinogen structure-function relations under shear is of considerable importance in developing a comprehensive understanding of the pathophysiology of thrombogenesis. Previously, we reported on molecular level AFM images of human vWf during shear-induced structural transition and human fibrinogen under aqueous conditions when both proteins were adsorbed on a hydrophobic surface. This presentation will report on the shear dependent interactions of dimeric and multimeric vWf with a hydrophobic surface and the substrate-dependent interactions of fibrinogen.
AFM and Fractal Analysis of Biomaterial Microtopography
Authors: Jo S , Li T , Park K
Published: July 2020

Although significant advances have been made in the development of biocompatible materials, currently available biomaterials still present a number of problems for in vivo applications. One of the attempts to improve the biocompatibility, especially blood-compatibility, of biomaterials has been surface modification. Typically, poly(ethylene glycol) (PEG), albumin, heparin, and phospholipid molecules are grafted to the surface to prevent protein adsorption and cell adhesion. We have been modifying biomaterial surfaces by covalent grafting of PEG and albumin. The control and modified surfaces were examined using an atomic force microscope (AFM). In this study, we examined the surface topography changes by surface modification using PEO grafting to glass as a model system.

Glass surfaces were modified with PEO using (N-triethoxysilylpropyl)-Omonomethoxy PEG urethane (PEG-Si), a PEG derivative containing a hydrophobic carbon chain and triethoxysilyl group at one end of the PEG chain. The presence of the hydrophobic carbon chain allowed self-assembly on the surface and triethoxysilyl resulted in covalent bonding to glass surfaces
Use of Polarized Light Microscopy to Measure Internal Strains of Collagenous Tissues.
Authors: Vesely I
Published: July 2020

When studying connective tissues, it is often necessary to develop an understanding of their internal mechanics. In the aortic valve, studying of the internal strains of the leaflet material has provided insight into the means through which these largely avascular tissues survive up to 3 billion loading cycles during their functional lifespan. Even the inert, “dead” bioprosthetic valve replacements can withstand hundreds of millions of cycles before wearing out. The durability of the natural and prosthetic valves is therefore highly dependent on their microstructure and internal micromechanics.

Conventional microscopy has shown the aortic valve leaflet to consist of two structural layers, the fibrosa and ventricularis, separated by a loose central spongiosa rich in proteoglycans (figure 1). Both layers are highly organized, consisting of layers of elastin and collagen fibers. As the valve leaflets stretch and bend during opening and closure, these collagen fiber layers elongate, compress and shear in response to the applied external forces.