bluuebunny/crossref_metadata_2025 huggingface dataset:
Aligned Carbon Nanotubes by Pyrolysis of Pyrodine and Ferrocene
Authors: Qian D , Dickey E C , Andrews R , Jacques D
Published: July 2020

Carbon nanotube (NT) growth by chemical vapor deposition (CVD) requires a catalyst -typically a transition metal- to nucleate NT growth because of the low synthesis temperatures as compared to arc-discharge or laser ablation methods. The catalyst can be introduced to the CVD system by preprepared nano-scale catalyst particles sitting on fine support powders, thin catalyst films deposited on substrates by sputter deposition, or floating catalysts. The floating-catalyst CVD method is an in-situprocess in which the organo-metallic precursors (e.g. metallocenes) decomposed to form nanoscale catalyst particles. Floating catalyst methods can produce both multi-wall carbon nanotubes (MWNTs), single-wall nanotubes, and even C-N nanotubes and facilitate continuous growth processes. in this study we employ a variety of electron imaging, diffraction and spectroscopy techniques to investigate the growth mechanisms and kinetics of multi-walled NTs (MWNTs) produced by the floating-catalyst CVD method.
The Stem Vasculature of Na1/Na1 and Na2/Na2 Mutants in Maize
Authors: Cheng Wayne Y , Cheng Ping-chin , Gu Miṅ , Gan Xiaosong , Walden David B
Published: July 2020

The vasculature of two recessive dwarf mutants, nana-1 (nal) (FIG 1) and nana-2 (na2) (FIG 2) of maize (Zea mays)were studied. All the plants used in this study were grown at the field station of University of Western Ontario, London, Ontario, Canada, in the summer of 2000. The specimens were fixed in methanol, serially sectioned with a razor blade using a specially made jig. The image was obtained by using a modified Acer 620T flat-bed scanner in liquid (Cheng et al., 2001). The optical sections were obtained by twophoton florescence microscopy using an Olympus Fluorview FL300 confocal microscope equipped with a Spectra-Physics Mai-Tai tunable ultra-fast Ti-sapphire laser. Excitation wavelengths was set at 780nm NIR with a pulse width of l00fs, <550nm autofluorescence was detected. Extended focus views were generated by using AutoQuant's AutoVisualize-3D™ software.

Different from the parallel arranged longitudinal vascular bundles commonly found in the internodes of wild type, nal/nalhas a complex stem vasculature (FIG 3)(Cheng et al., 2000a; 2000b).
Distribution and Function of Filamentous and Globular Actin in Mitochondrial Translocation During Ascidian Sperm Activation
Authors: Zebadua E , Blackwell L , Koch RA
Published: July 2020

During fertilization in the sea squirt, Ascidia ceratodes,the penetration process of requires mitochondrial translocation, a process that defines sperm activation in this species, to generate the driving force for passage through the vitelline coat. When a sperm cell come into contact with an egg, the mitochondrion translocates off the head and migrates along the tail via an actimmyosin-dependent process. The presence of actin and myosin on the head and tail has been demonstrated. However, the nature of the relative distribution of filamentous actin (F-actin) and monomeric actin (G-actin) has not been thoroughly studied. And, whereas the signaling cascade that leads to myosin activation has been studied, the events leading to actin polymerization and whether it is required for mitochondrial translocation has not.

This project addresses two research questions: What is the distribution of F-actin and G-actin in unactivated and activated sperm cells? And, can preexisting F-actin support mitochondrial translocation or must actin polymerization occur simultaneously with the mitochondrial translocation process?
Diversity of Sperm Cell Architecture in Ferns
Authors: Johnson Thomas H , Schmitt Steven J , Renzaglia Karen S
Published: July 2020

Among land plants, lower vascular plants produce the most elaborate of all male gametes. in order to characterize the degree of variability in sperm cell architecture among ferns, this scanning electron microscope study was undertaken on three highly disparate genera: Ceratopteris(a derived leptosporangiate fern) Angiopteris(a derived eusporangiate fern) and Psilotum(a putatively basal eusporangiate fern).

Mature gametophytes were placed in 0.01M phosphate buffer (pH ca. 7.2) or distilled water until spermatozoids were released. Gametophyte portions were removed and the spermatozoid suspension fixed with 2% glutaraldehyde in 0.05M phosphate buffer. Post-fixation utilized 1% aqueous osmium tetroxide for lhr, followed by rinsing and dehydration in ethanol (10 min @ 25, 50, 75 and 100%). The dehydrated pellet was suspended in 100% hexamethyldisilazane, immediately centrifuged and the pellet deposited onto clean glass coverslips. Specimens were dried at 60°C, sputtered with ca. 350 A of palladium/gold and imaged in a Hitachi S570 SEM.
Developing a Database of Pollen Images
Authors: Spier R A , Thompson J M
Published: July 2020

A database cataloguing SEM micrographs of pollen specimens can be useful for several purposes. The primary reason would be for educational purposes. The images could be used to study pollen structure, as well as the relationship between pollen and pollinator species. Identification of pollen can be of potential use for medical purposes (such as combating allergic reactions to pollen), and for comparison in a forensic investigation. At the Biology Department of California State University, San Bernardino an ongoing project is underway to construct a database of pollen samples, focusing on local species. The micrographs are created at the Electron Microscope and Images Analysis Center located in the School of Natural Sciences at Cal State San Bernardino using a Hitachi S-2700 SEM. The database will be made available to the public and updated periodically via the Biology Department website (http://biology.csusb.edu).

All specimens were first fixated by placing the pollen grains in a syringe filter and injecting a 2% formaldehyde/4% glutaraldehyde formula and incubating overnight.
Electrochemical Deposition of Molybdenum Nanowires for Use as Sensors
Authors: Zach Michael P , Inazu Koji , Hemminger John C , Penner Reginald M
Published: July 2020

Electrodeposition of molybdenum dioxide (using the step edges of highly oriented pyrolytic graphite as nucleation templates) is used to form precursor nanowires ranging in diameter from 10 nm to one micron with many exceeding one-half millimeter in length. Subsequent treatment with hydrogen gas above 500°C reduces the wires to conductive metallic molybdenum. (Science, December 15, 2000, 290 (5499) 2120, selected as cover story). Currently, this is the only method which exists to create millions of ordered nanowire arrays with such high aspect ratios. A film of either polystyrene or cyanoacrylate polymer is used to lift the wires off of the conductive graphite substrate making electronically isolated wires. Electronically isolated wires such as these hold promise to be sensors, electronic interconnects or as precursors for growing more complex electrodeposited circuitry.

The discovery of a method to deposit nanowires is just the beginning. By using a piece of a double-sided copper-clad circuit board as a support, the polymer containing nanowires can be made into a robust sensor device.
Daily Analytical Problem Solving in Criminalistics with Rapid and Reliable Advanced Instrumentation - the Microscope
Authors: Moorehead W
Published: July 2020

Forensic science incorporates many different scientific disciplines: criminalistics, toxicology, pathology, entomology, engineering, psychology, accounting, etc. Criminalistics incorporates such diverse areas as crime scene investigation, sexual assault evidence, DNA analysis, firearms identification and comparison, drug analysis, impression evidence, and trace evidence.

A variety of microscopes and microscopical techniques are used to answer “real world” questions about physical evidence in criminalistics. The microscopes most often used include stereo (dissecting), biological (brightfield), polarizing light, phase contrast, fluorescence, transmitted light comparison, reflected light comparison, and scanning electron. Additionally, detectors from different areas of the electromagnetic spectrum have been added to microscopes to enhance the information obtained from a specimen: infrared, visible-ultraviolet, and x-ray. to gather more information about the specimen with visible light microscopes, dispersion staining(1), contrast enhancement techniques(2) fusion methods(3), chemical staining(4), and micro-chemical tests(5,6) can be integrated into the analytical scheme.
Teaching the Microscopy of Indoor Air Quality - Lessons and Implications for the Future of the Science
Authors: Shane John
Published: July 2020

Indoor air quality concerns are becoming increasingly important in the United States as a result of a greater awareness of the harm fungi can cause to structures and the people living in those structures. By making our homes and offices more energy efficient and by making heating and ventilation systems more complex we have also created some indoor air quality problems.

Microscopical indoor air investigations are growing rapidly as evidenced by the number of asbestos and other labs getting into the fungal spore identification business. Many companies are growing by 20% a month and cannot find enough qualified microscopists to perform the identification of the fungi..

There is a real need to revitalize the teaching of light microscopy to solve indoor air problems. Fungal spores and pollen are the common culprits that cause indoor air quality problems that can be studied with the light microscope. with proper training, an indoor air quality investigator can make better use of their elegant analytical tool, viz.
In SEM a New Method of Internal Micrographic Visualization of Semiconductor Materials and IC by Crossing the Surface
Authors: Xiao Ling , Liang Zhuguan , Li Yawen , Wang Jian , Zhou Kailin , Li Ping , Xu Xiaohua , Rau EI , Hu Wenguo
Published: July 2020

In the paper, we firstly publish a new method of internal micrographic visualization of semiconductor and IC. The quality and reliability of the semiconductor materials (SM) and the integrated circuits (IC) have always been concerned Having a high resolution, high reliable and nondestructive detection method is the key element for their improvements.

Silicon oxide layers are used to provide the electrical insulation in the multi-structured ICs. The IC device surfaces are often protected by silicon oxide and silicon nitride layers. Therefore, these insulation layers also cover any inhomogeneity and defect located within the IC devices. It is necessary to have an examining method to detect those defects that are under the insulation layers without damaging the samples. However, the conventional scanning electron microscope (SEM) cannot be utilized to image and examine the surfaces that are positioned below the insulation layers.

Novel nondestructive and contactless method has been developed in our laboratory to obtain the internal micrograph that crosses the surface of the semiconductor material and the integrated circuit.
In SEM Study of Physical Properties of Semiconductor by Surface Electron Beam Exciting Potential
Authors: Hu Wenguo , Zhu Shiqiu , Rau EI
Published: July 2020

In this paper, we apply a novel contactless method that we study to investigate the physical properties of the semiconductor materials. This method is based upon the measurement of the surface electron beam exciting potential (SEBEP) on the sample surface. Its advantages include: no direct sample contact or connection needed that is unlike the electron beam inducing current (EBIC) method; no potential barrier required from the measurement.

Electron probe irradiation can cause bending of the energy bands, variation of carriers and excitation of surface potential. The excited surface potential generates the SEBEP signal that can be detected by a SEBEP detector. It is necessary to emphasize that the electron beam can charge the surface that is under the oxide layer when it passes through the sample surface oxide layer.

It is known that the diffusion length L and the average lifetime τ of the non-equilibrium carries can be measured by other methods such as the cathodoluminescent method and the contacting method..
Semiconductor Microscopy - Microscopy at the Instrumental Performance Limit
Authors: Tracy Bryan M
Published: July 2020

The microscopy to support process development of Si-based semiconductors has consistently required state-of-the-art instrumentation. As the industry strains to achieve 1 OOnm design rules, this requirement has never been more pronounced. This paper presents TEM, SEM and FIB examples with a focus on using the instrumentation near the performance limit.

Transmission Electron Microscopy - The high contrast and high resolution images provided by the TEM have made this “research instrument” into the mainstay of the semiconductor analysis laboratory. For the vast majority of samples, both plan view and cross sections, precious little tilt is required. For cross sections, +/- 3 degrees is usually adequate to bring the silicon into (110) orientation and plan views are commonly made from polycrystalline films, which benefit more from choosing the right thickness than from tilt. Under appreciated is the benefit of very high resolution polepieces which have superior spherical and chromatic aberration coefficients producing real improvements in image quality.
Semiconductor Failure Analysis Using EBIC and XFIB
Authors: Rice Larry
Published: July 2020

Electron beam induced current (EBIC) is the common term used in the semiconductor industry for the failure analysis and yield enhancement of semiconductor devices using SEM to electrically pinpoint leakage sites. EBIC is a useful technique for locating defects in diodes, transistors, and capacitors where the scanning electron microscope beam is used to generate a signal and the sample is the detector. Often during yield enhancement efforts the failure analyst is asked to determine the mechanism for which a PC structure (which may contain as many as a few hundred thousand structures in one device) is failing tests. Blind cross sections rarely give evidence of the failure mechanism. EBIC can be used to pinpoint the bad site which is then precision cross-sectioned using the focused ion beam (FIB).

When an electron beam impinges on a semiconductor such as silicon, electron-hole pairs are created when the incident beam transfers enough energy to promote an electron from the valance band to the conduction band.
Microscopy in the Real World - Instrumentation Requirements
Authors: Cunningham Brian
Published: July 2020

In the last two decades, microscopy, in particular transmission electron microscopy, has moved from the research environment into industry. As such, the user requirements of the microscopes have changed. Previously, users required the highest performance in all aspects of microscopy e.g. imaging, analytical capabilities, with little regard to other factors. Today, additional requirements are being placed on areas such as ease of use, reliability, high throughput, expanded sample requirements, and networking capabilities. However, the “high performance” aspects of the instrumentation are still a high priority to the end user. These user requirements cause microscope manufacturers a dilemma in many instances. It is not always possible to provide the “new” requirements while still maintaining the high performance of the instruments, at a “reasonable” cost. An example is the large sample requirements in scanning electron microscopes. Large stages are inherently more prone to vibration than smaller stages, and therefore adversely affect resolution.
The Tem Evolved from a Lab Experiment Into an Analytical Tool
Authors: Van Cappellen E , Ringnalda J , Wang YC , Bormans B , Fliervoet T
Published: July 2020

It all started in Berlin in 1931 where Dr. Ernst Ruska built the first TEM with 2 magnetic lenses. Three years later a third lens was added and a resolution of l00nm was demonstrated, just enough to beat the light microscope by a factor of two. His achievements and vision was acknowledged and celebrated in 1986 when he was awarded the Nobel Prize for Physics. Philips’ commitment to electron microscopy dates back to the mid-1930s, when it collaborated in EM research programs with universities in the UK and the Netherlands. in 1949, the company introduced its first EM production unit, the EM 100 transmission electron microscope, which already was a significant step forward in terms of ease of use and reliability.

In fifty years the TEM has come a long way; enumerating all the milestones would be too lengthy.
Comparative Study of Oak Species for Intercepting Particle Pollution
Authors: Abdollahi Kamran K , Ning Zhu H
Published: July 2020

Trees can act as efficient biological filters to remove significant amounts of particulate pollution from urban atmospheres (Nowak, et al. 1994 ). Recent controlled environment studies have indicated that tree's ability in intercepting and removing particle pollution varies among species. Studies by Abdollahi et al. (2000) confirmed that there were significant differences among different tree species in intercepting particle pollution. Live Oaks (Quercus virginiana), River Birch ( Betula nigra),and Sugar hackberry (Celtis occidentalis) are statistically more efficient at capturing pollutant particles of less than 2.5 microns (PM2.5) than tree species such as Red Maple (Acer Rubrum),Southern Magnolia (Magnolia grandiflora),and Sycamore (Platanus occidentalis).Other Studies also suggested that the leaf surface morphology of these trees might play an important role in interception and removal of PM2.5.

The main objectives of this study were to quantify the relative ability of selected oak species (Quercus spp.) in removing particle pollution of less than 2.5 microns (PM2.5) and to characterize oak leaf surface morphology.
Precise Microanalysis of Biological Remains Using a Process of Laser Ablation
Authors: Plinski Edward F , Witkowski Jerzy S
Published: July 2020

A precise analysis of the biological remains is presented in the paper. A single-channel waveguide carbon dioxide laser is used in a process of ablation ‘ for the exposing of biological remains of mineralised organisms found in a sea slime used as a component in some technological process.

Many important applications of the laser base on the process of ablation. These include also so precise biomedical uses like structural studies of biomolecules. Among of the wide range of the laser devices the waveguide carbon dioxide lasers can be used in a precise biological investigations. A single-channel waveguide CO2 laser emits very easy the optical wave formed in a single, so called quasi-Gaussian, mode2. The distribution of the intensity of the laser output radiation in a basic Gaussian mode is shown in Figure 1. A high quality laser output beam in a basic Gaussian mode can be easy focused permitting a precise ablation of the investigated material in a very small area of 100 μm and less.
Microanalysis for Design and Development of Improved High-Temperature Alloys
Authors: Maziasz Philip J
Published: July 2020

Alloy development can range from purely empirical, trial-and-error efforts to very theoretical, based on either fundamental first-principles calculations or computational-modeling using various kinds of data base inputs. However, “real-world” efforts to improve or optimize complex engineering alloys often cannot afford the time or cost of either extreme approach. in the past 10-15 years, an alloy development and processing optimization methodology has been developed that utilizes strategic microanalytical data (both detailed microstucture and microcompositional information) as the critical input that then enables efficient and effective design of various kinds of alloys for improved high-temperature performance [1-6]. in many cases, first time tests produce outstanding high-temperature creep or creep-rupture results, and enable improvements without trading off one property for another. This invited paper will highlight several examples of significantly improved creep resistance obtained using such microstructural design.

This microstructural design methodology for high-temperature creep-resistance was initially developed for and demonstrated in austenitic stainless steels (Fe-14Cr-16Ni) designed for improved creep-strength and rupture resistance at 700°C and above for superheater and boiler tubing in advanced fossil power plants.
“Real-World” Microanalytical Tools for Accelerated Alloy Development
Authors: Hall Ernest L
Published: July 2020

Conventional microanalytical tools, particularly analytical electron microscopy (AEM), electron probe microanalysis (EPMA), and powder x-ray diffraction (XRD), have been traditionally used in the development of new engineering alloys to determine the identity of phases in new materials, their composition, phase equilibria, and the subsequent effect on properties. Recently, there has been a growing effort in industry to reduce the cycle time (and lower the cost) associated with new material development. This is particularly true for the advanced alloys needed for high-temperature components in power generation and aerospace application. This has led first to the development of more rapid screening methodologies, such as combinatorial approaches, where a large number of compositions can be evaluated in parallel, or the diffusion multiple method, where multi-component phase space is investigated in a single experiment. These new approaches require new analysis tools that can rapidly assess crystal structure and composition in automated fashion.
Characterization of Nanoscale Clusters in Ods Iron-Based Alloys
Authors: Kenik EA , Hoelzer D , Maziasz PJ , Miller MK
Published: July 2020

The high temperature application of iron-based ferritic alloys is limited by their rapid decrease of yield strength at temperatures approaching 1000°C. It has been shown that mechanical-alloying (MA) to produce oxide dispersion-strengthened (ODS) ferritic alloys improves their high temperature mechanical properties. Prior characterization of such materials has shown that in certain as-processed alloys the original yttria oxide particles are replaced by nanoscale (2-5 nm diameter) clusters containing Ti, Y and O. As a result of the high density of these fine clusters, dislocation pinning produced a ∼10-fold increase in dislocation density relative to similar ODS materials not exhibiting the nanoscale clustering. The improved creep resistance of the clustered material was attributed both to the higher dislocation density, additional dislocation pinning and resistance to recovery during creep. The current work examines clustering in a related alloy, as well as the effects of high temperature creep on the stability of such clusters.
Microscopy of Industrial Ceramic Materials
Authors: Bateman CA , Kilgore JJ , Smaltz PJ
Published: July 2020

The microscopy effort within the Saint-Gobain R&D labs involves working with a wide variety of ceramic materials. Samples vary from routine QC type work, to manufacturing plant emergencies, to failure analysis, to marketing support. A typical sample will require a variety of techniques to provide a solution within a few working days. Working in such an environment it is essential that people are aware of the different analytical tools that can be utilized in a given situation. For the microscopists in our lab this means a working knowledge of the techniques that are close to our core competencies centered around optical microscopy and SEM; these include AFM, XRD, Auger, SIMS, and FTIR, which are all used in a complimentary fashion. The examples shown here are illustrative of the kinds of problems worked on and the interactive nature of the solutions.

XRD of a siliconized silicon carbide material showed that it contained a higher fraction of the beta phase than was expected.
Transmission Electron Microscopy Study of the Microstructure of Np- Etched CdTe Thin Films
Authors: Jones KM , Yan Y , Hasoon FS , Al-Jassim MM
Published: July 2020

Polycrystalline CdTe is a promising candidate for solar cells due to its nearly ideal band-gap, high absorption coefficient, and ease of film fabrication. Small-area CdTe/CdS cells with efficiencies of 16.0% have been demonstrated. The structure of a typical CdTe/CdS solar cell (Figure 1) consists of a glass superstrate, on which a thin layer of SnO2 is deposited (front contact), n-type CdS, p-type CdTe, and a back contact. Prior to applying the back contact to the CdTe, etching of the CdTe surface using a mixture of nitric and phosphoric (NP) acids is normally needed. It is known that the etching depletes a crystalline CdTe surface of Cd and creates a Te-rich layer. Two effects of the Te-rich layer has been proposed, namely, forming a Te-CdTe low-series-resistance contact and improving CdTe device stability by the gettering of Cu. Thus, the NP etching is an important process in the CdTe device fabrication. in this paper, we report on transmission electron microscopy (TEM) study of the microstructure of the surface of NP etched CdTe thin films.
EBIC Measurements of Minority Carrier Diffusion Length in a Gan-based Light Emitting Diode
Authors: Bunker KL , Gonzalez JC , Russell PE
Published: July 2020

This study involved the application of the Scanning Electron Microscope (SEM) for the characterization of a GaN-based Light Emitting Diode (LED) by the Electron Beam Induced Current (EBIC) method. The diffusion length of the minority carriers in both the p and n-type regions of a GaN-based LED structure was determined with the EBIC technique in the line scan configuration. The diffusion length is a critical physical parameter that directly affects the electrical and optical properties of these devices. This value is generally understood to be a material property of the layers within a device. However, the measured values of the diffusion length are sensitive to the sample design, experimental conditions, measurement technique, and data analysis model and method utilized.

The EBIC measurements were performed at room temperature in a Hitachi S-3200N SEM using a GW Electronics Type 31 Specimen Current Amplifier.
Semiconductor Dopant Profiling by Off-Axis Electron Holography
Authors: Li Jing , McCartney MR , Smith David J
Published: July 2020

Two-dimensional dopant profiling continues to be a topic of great interest and importance to the semiconductor industry. Off-axis electron holography provides access to the phase of the electron wavefront that has traversed a sample, and it thus enables voltage contrast to be visualized. The technique was used by McCartney et al. (1994) to observe the potential distribution across Si/Si p-n junctions [1], and it was later also used by Rau et al. (1999) to map the two-dimensional electrostatic potential in deep-submicron transistor structures [2]. in this paper, we have used electron holography and a known test structure to demonstrate that accurate voltage profiles can be extracted under carefully controlled sample preparation conditions. Carrier information can be obtained using a simulation program. Experimental factors that affect quantitative measurement are also discussed.

The sample studied was a test structure fabricated at IBM for comparison of various profiling methods [3]. Both p-n junctions and p-p+ regions were available for study.
Quantitative Model-Based Image Analysis of NuMa Distribution Links Nuclear Organization with Cell Phenotype
Authors: Knowles David W , Lelièvre Sophie A , de Solόrzano Carlos Ortiz , Lockett Stephen J , Bissell Mina J , Sudar Damir
Published: July 2020

The extracellular matrix (ECM) plays a critical role in directing cell behaviour and morphogenesis by regulating gene expression and nuclear organization. Using non-malignant (S1) human mammary epithelial cells (HMECs), it was previously shown that ECM-induced morphogenesis is accompanied by the redistribution of nuclear mitotic apparatus (NuMA) protein from a diffuse pattern in proliferating cells, to a multi-focal pattern as HMECs growth arrested and completed morphogenesis. A process taking 10 to 14 days.

To further investigate the link between NuMA distribution and the growth stage of HMECs, we have investigated the distribution of NuMA in non-malignant S1 cells and their malignant, T4, counter-part using a novel model-based image analysis technique. This technique, based on a multi-scale Gaussian blur analysis (Figure 1), quantifies the size of punctate features in an image. Cells were cultured in the presence and absence of a reconstituted basement membrane (rBM) and imaged in 3D using confocal microscopy, for fluorescently labeled monoclonal antibodies to NuMA (fαNuMA) and fluorescently labeled total DNA.
The Role of the Centrosome in Development and Progression of Breast Cancer
Authors: Lingle W , Salisbury J , Barrett S , Negron V , Whitehead C
Published: July 2020

The centrosome is the major microtubule organizing center in most mammalian cells, and as such it determines the number, polarity, and spatial distribution of microtubules (MTs). Interphase MTs, together with actin and intermediate filaments, constitute the cell's cytoskeleton, which dynamically maintains cell polarity and tissue architecture. Interphase cells begin Gl of the cell cycle with one centrosome. During S phase, the centrosome duplicates concomitantly with DNA replication. Duplicated centrosomes usually remain in close proximity to one another until late G2, at which time they separate and then move during prophase to become the poles that organize the bipolar mitotic spindle. During the G2/M transition, interphase MTs depolymerize and a new population of highly dynamic mitotic MTs are nucleated at the spindle poles. The bipolar mitotic spindle apparatus constitutes the machinery that partitions and separates sister chromatids equally between two daughter cells.
Characterization of Mitochondrial Function During Cell Injury
Authors: Nieminen Anna-Liisa
Published: July 2020

Mitochondria play an important role in apoptotic and necrotic cell death. Depending on the stimulus, a variety of mitochondrial dysfunctions can trigger onset of cell death. Assessment of mitochondrial dysfunction in living cells in situis important to understand the sequence of events producing cell injury and death. Laser scanning confocal microscopy, a technique that creates submicron thin optical slices through living cells and tissues, allows us to monitor several mitochondrial events simultaneously in intact single cells over time.

During oxidative stress, we monitored mitochondrial redox status, Ca2+ increase, reactive oxygen species (ROS), the mitochondrial permeability transition, and mitochondrial depolarization in cultured hepatocytes. When an oxidant chemical, t-BuOOH, was added to cultured hepatocytes, oxidation of mitochondrial pyridine nucleotides occurred as visualized directly by ultraviolet confocal microscopy of NAD(P)H autofluorescence. This event was followed by an increase of mitochondrial Ca2+ measured by the Ca2+-indicating fluorophore, Rhod-2.
An Introduction to Flow Cytometry in Correlative Fluorescence Studies
Authors: Smith R W
Published: July 2020

In the last few years there has been a mild explosion in both microscopy and cytometry. in part, this has been a more sensitive understanding of new fluorescent chemicals or probes as well as the ability to transfect fluorescent proteins into cells. in part, this has also been a case of substantial improvement in instruments, electronics, computers, lasers and sensors. in this session, we hope to examine correlative and comparative methods that may improve the quality of data.

This is an introduction to session 29, Correlative Fluorescent Microscopy and Flow Cytometry Techniques, and the first time the Microscopy Society of America has sponsored a session that involves flow cytometry. Flow cytometry offers several statistical advantages over standard microscopies in evaluating populations of cells. Flow cytometry also facilitates a statistical precision in evaluating fluorescence and fluorescence changes in both chemical probes and transfected fluorescent proteins.
Dual Wavelength Evanescent Field Microscopy of Exocytosis and Endocytosis in Single Cells
Authors: Merrifield C , Feldman M , Almers W
Published: July 2020

The plasma membrane defines the outer limit of eukaryotic cells and it is here that cells interact with their environment through receptor proteins. Clearly the management of cell surface receptor concentration is critical for normal cellular function, and this is achieved through two key processes, exocytosis and endocytosis. During exocytosis transport vesicles containing both membrane receptors and soluble cargo fuse with the plasma membrane releasing cargo and delivering receptors to the cell surface. During clathrin mediated endocytosis receptors destined for internalisation become concentrated in clathrin coated pits before coat invagination and membrane fission. Since transferrin receptors are recycled and undergo numerous rounds of exocytosis and endocytosis by labeling transferrin receptor with an appropriate fluorophore it is possible to label both exocytic and endocytic organelles in the same cell. We have exploited this phenomenon to visualise the spatial and temporal organisation of constitutive exocytosis and endocytosis at the surface of single cells using dual wavelength evanescent field microscopy.
Cell Imaging in Drug Discovery and Development
Authors: Keller G-A
Published: July 2020

While morphological analysis at both the light and electron microscopical levels has been fully exploited in academic research, its potential in biopharmaceutical industry has only been fully appreciated in recent years. The biotechnology industry has been developing highly specialized therapeutic molecules, particularly proteins and peptides that are directed to specific molecular targets. The pace of the development of new therapeutic molecules is expected to increase dramatically in the close future, as the biopharmaceutical community will capitalize on the new targets identified by the Human Genome Project.

An efficient drug discovery and development effort should not only include the characterization of the tissue and intracellular distribution of potential targets, but also establish unambiguously that the therapeutic entities reach their intended targets. It has become apparent in recent years that a comprehensive view of the pharmacological action of drugs must include not only the pharmacokinetic parameters but also the tissue distribution and the cellular localization.
Digital Microscopy Imaging in Drug Discovery and Development
Authors: Ying Xiaoyou , Sprinkle Cavallo Jean , McCullough Bruce
Published: July 2020

Digital microscopy, the integration of digital and microscopy technologies, was initiated for quantitative microscopic image analysis, but it is now for almost all microscopy applications. During the past decade, with the advance of digital technologies, digital microscopy imaging is becoming an indispensable technology in drug discovery.

We started establishing state-of-the-art digital microscopy imaging for drug discovery with the investigation of bioimaging applications at our US research site. Our results shown that all the top 5 bioimaging needs require computer-aided microscopy. Based on this investigation and our review of the microscopy imaging applications in the pharmaceutical industry, we determined four directions for microscopy in drug discovery: multidimensional/multimodal microscopy, digitalization, automation, and bioimage informatics.

Multidimensional/multimodal microscopy imaging is required by the nature of biological research, which is fundamental in drug discovery. From genomic imaging to pathology observation, we require biological details and compound activities at the levels from subcellular organelles to organ tissues, from cellular signaling to anatomical locations of compounds.
Crystal Structure Data for Efavirenz (Sustiva™) by Combined Synchrotron X-Ray Diffraction and Electron Microscopy Techniques
Authors: Li Z G , Harlow R L , Marshell W , M. Foris C , Murphy D , Maurin M
Published: July 2020

Efavirenz (Sustiva™) is a non-nucleoside reverse transcriptase inhibitor (NNRTI) for the treatment of HrV-infected patients and has been in the market since 1998. Efavirenz exists as three different polymorphs (Forms I, II, III) and a nonstochiometric heptane solvate (Form IV). The current synthetic process for Efavirenz yields Form IV which is converted to the desired Form I polymorph by heating. One of the concerns for any drug substance is whether a consistent crystal form is produced in order to insure consistent physical and chemical properties, as well as to safeguard pharmacokinetic profiles. The sensitivity and resolution of single-crystal x-ray diffraction, the traditional method employed to determine unit cell parameters of drug compounds in development, are limited for Efavirenz Form IV because of the small crystallite size of the material. Furthermore, Efavirenz Form IV materials, depending on the process conditions, have slightly different powder diffraction patterns in terms of intensity when collected on standard in-house diffractometers.
Microscopic Analysis of Oxidative Stress in Cultured Cells. I. Confocal Microscopy
Authors: Maleeff Beverly E , Gales Tracy L , Narayanan Padma K , Tirmenstein Mark A , Hart Timothy K
Published: July 2020

Cellular oxidative stress, a common mechanism of drug-induced toxicity, is a result of the formation of reactive oxygen species (ROS) in response to chemical stimuli. An endpoint of ROS production is lipid peroxidation, which can in turn lead to disruption of cellular membranes, loss of mitochondrial function, protein oxidation and DNA damage. This toxicity can be organ-specific due to the varying capacities of tissues to handle oxidative events. Liver is particularly sensitive to the effects of oxidative stress, and hepatic toxicity is seen clinically. HepG2 cells are an immortalized human hepatoma cell line used as an in vitro model for mammalian hepatotoxicity studies. The purpose of this study was to characterize the effects of chemically induced oxidative stress in this cultured cell model.

HepG2 cells were grown to subconfluence in poly-L-lysine coated 4-well LabTek™ II chambered coverglasses (Nalge Nunc International).
Role of Plasmalemmal Vesicles on the HDL-Mediated Cholesterol Efflux in Aortic Endothelial Cells
Authors: Chao W T , Yang V C
Published: July 2020

It is well-known that high-density lipoprotein (HDL) mediates the transport of cholesterol from peripheral tissues to liver through “reverse cholesterol transport” for metabolism. However there is considerable debate about the mechanisms by which HDL removes excess cholesterol from cells. Two different pathways have been suggested: (i) a docking receptor promots cholesterol translocation, or (ii) a receptor mediates intracellular endosomal pathway termed “retroendocytosis“. Our previous studies have indicated that the removal of cholesterol from aortic endothelial and smooth muscle cells in the presence of HDL is facilitated by plasmalemmal vesicles. in this study, our emphasis is on the ultrastructural changes of cholesterol-loaded endothelial cells after incubated with HDL at different time intervals. Furthermore, the mechanism of HDL-mediated cholesterol efflux by cultured aortic endothelial cells is investigated by immunoelectrophoresis.

Confluent monolayers of endothelial cells were incubated in cholesterol DMEM medium for 48 hr.
Sulfur Mustard-Induced Apoptosis in Hairless Guinea Pig Skin
Authors: Kan RK , Pleva CM , Hamilton TA , Petralì JP
Published: July 2020

Sulfur mustard [bis-(2-chloroethyl)sulfide; HD] causes incapacitating injuries to the eyes, respiratory tract, and skin. Despite decades of research, the mechanism of toxic action of HD is still poorly understood. One proposed toxicological mechanism that triggers cell death involves DNA damage induced by HD alkylation. According to this hypothesis, HD-induced DNA damage activates NAD+, requiring the enzyme poly(ADP-ribose) polymerase (PARP) to initiate DNA repair processes. Overactivation of PARP leads to depletion of NAD+, and, in efforts to resynthesize NAD+, cellular ATP is depleted, and the cell dies from intracellular energy. However, recent studies only partial support this hypothesis. Niacinamide, a substrate for NAD+ synthesis, prevented NAD+ depletion, but did not significantly prevent cell death following HD exposure. These studies suggest cell death occurs independently of depletion of cellular NAD+ with some other pathogenic processes operating in cell death following HD cytotoxicity.

The present study examined the role of apoptosis in basal cell degeneration caused by HD exposure in the hairless guinea pig.
Intraspinal Bronchogenic Cyst: Ultrastructural Study of Abnormal Cilia
Authors: Ho Khang L
Published: July 2020

Intraspinal cyst formed of tissue proper to the tracheobronchial tract has been referred to as bronchogenic cyst. Six cell types of the cyst epithelium have been identified, i.e., ciliated cells, non-ciliated cells, goblet cells, basal cells, Kulchitsky's cells and undifferentiated cells. This report described the detailed morphological alterations of cilia of the lining epithelium of three cases of intraspinal bronchogenic cyst and compared the findings with the ciliary abnormalities of the tracheobronchial epithelium.

Ultrastructural abnormalities of cilia of the intraspinal bronchogenic cyst could be classified into five categories:

(A) Cilia showing addition, deletion or disorganization of axonemal minotubules. (B) Swollen cilia containing a single axoneme in an excess amount of matrix: (a) normal 9 + 2 axoneme,(b) stretched axoneme bending toward one side, (c) abnormal axonemal pattern. (C) Compound cilia with multiple axonemal microtubules ensheathed by a common ciliary membrane: (a) two or more normal 9 + 2 axonemes, (b) two or more normal 9 + 2 axonemes sharing doublets, (c) giant compound cilia with numerous normal and abnormal axoneme in random orientation, (d) compound cilia containing cytoplasmic organelles, (e) compound cilia with excessive matrix.
Confocal Scanning Laser Microscopy, Scanning and Transmission Electron Microscopy of Vertebrate Cerebellar Granule Cells
Authors: Castejón O J , Castejón HV , Apkarian R P
Published: July 2020

The cerebellar granule cells of hamsters, mice, primates and human have been examined to study their organisation, outer and inner surfaces, pattern of connectivity on granule cell groups and synaptic relationships with afferent mossy and climbing fibers in the granule cell layer and with Purkinje cell dendritic spines in the molecular layer.

Confocal laser scanning microscopy of hamster cerebellum cortex, using FM4-64 as an intracellular stain, showed in z-series of stacks of optodigital sections, the presence of granule cell groups formed by small, medium and large granule cells, ranging from 3-10 μm in diameter, surrounded by large Golgi cells. The granule cell/Golgi cell ratio was 50 to 4 (Fig. 1).

Cryofractured mouse cerebellar cortex showed the inner organization of granule cell nuclear and cytoplasmic compartments in samples examined with FEURSEM and coated with chromium (Fig. 2), which were compared with corresponding freeze-etching replica images.
Fundamental Constants for Quantitative X-Ray Microanalysis
Authors: Joy David C
Published: July 2020

One of Prof. Castaing’s most important gifts to the field of X-ray microanalysis was his insight that quantification could only effectively be carried out by procedures which relied on measurements relative to a suitable standard, because in this way is was the functional variation, rather than the absolute value, of most quantities that had to be known or approximated. At the time this was seen to be a necessary step because the state of knowledge about the fundamental parameters of electron solid interactions was regarded as poor. in the intervening fifty years this situation has not changed very much. Even more unfortunately the kinds of problems to which electron beam microanalysis is now applied - such as the analysis of highly inhomogeneous or very small samples - are of such a nature that quantitative methods based on standardization are no longer feasible.
Some Electric Field Effects in the Microbeam Analysis of Insulators
Authors: Cazaux J , Belhaj M , Jbara O , Remond G , Odof S
Published: July 2020

Mechanisms in electrostatic charging of insulating materials during electron irradiation are very difficult to predict because they involve cross-correlated parameters: the surface potential, Vs and the secondary electron yield,δ, for bare specimens; the possible change of the bulk composition induced by the internal electric field for ground coated specimens. A better understanding of these mechanisms requires efforts from both the theoretical and the experimental points of view.

From the theoretical point of view, a two-layer model for distribution of the trapped charges (Q+ over the escape depth of the secondaries, s; Q- over the maximum penetration depth R of the incident electrons) often permits to account for many charging effects observed on bare specimens. For instance, the failure of the total yield approach may be partly explained by the fact that the charge distribution expected at the critical energy Ec2 (where δ+ η=l) corresponds to Q+=-Q- but also to R ≫ s at the early beginning of the SEM and EDS investigation.
Evaluation of a Lead Lanthanum Zirconium Titanate (Plzt) Specimen for Use as an Electron Microprobe Reference Material
Authors: Marinenko R B , Samardzija Z , Bernik S , Kosec M , Ceh M
Published: July 2020

Lead lanthanum zirconium titanate (PLZT), or (Pb,La)(Zr,Ti)O3 solid solutions, ferroelectric ceramics are being studied for electro-optical applications, as well as for high-speed electrophoretic printing. Thin films of a related material, lead zirconium titanate, or Pb(Zr,Ti)O3 solid solutions (PZT), are used for non-volatile memories and actuators.1 Proper composition and compositional homogeneity of ferroelectric ceramics are essential for application, however the fabrication process may produce materials with element concentrations and thus physical characteristics that may differ from expectation. Therefore, a PLZT reference material for determining the composition of these ceramics would be useful. It will also be useful for quantitative microanalysis; it is stable under the point beam of the electron microprobe (EPMA) at excitation voltages up to 25 kV and probably higher at currents of more than 100 nA.

A specimen of PLZT prepared by the Ceramics Department of the Jozef Stefan Institute in Ljubljana, Slovenia was studied with the electron microprobe to determine the composition and the extent of heterogeneity.
Application Ofthinfilm Method to Electronic Probe Microanalysis (EPMA)
Authors: Takahashi Hideyuki , Suzuki Toshiaki , Nielsen Charles
Published: July 2020

Usually, in electron probe microanalysis, the X-ray diffusion range is around lμm on the sample surface. For this reason, the maximum useful magnification of X-ray image seems to be limited to a few thousand times. The X-ray diffusion on the \im order takes place in the bulk sample. However, when a sample is cut to a thin film, it is likely that the X-ray diffusion range will be made smaller, and it is also possible to observe very a narrow area X-ray image at higher magnification. The thin film method is a sampling technique used often in transmission electron microscopy. The microtome method has been applied to organic materials, and the method using focus ion beam (FIB) has been applied to inorganic materials. Takahashi et al. have reported the effectiveness of the microtome application to EPMA of soft materials. in this report, the FIB method was applied to a sampling of inorganic materials in order to obtain high resolution X-ray images of real samples.