bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.
Optimizing Spatial Resolution for X-ray Microanalysis
Authors: Lifshin Eric , Gauvin Raynald , Wu Di 
Published: July 2020

Abstract
In Castaing’s classic Ph.D. dissertation he described how the limiting value of x-ray spatial resolution for x-ray microanalysis, of about 1 μm, was not imposed by the diameter of the electron beam, but by the size of the region excited inside the specimen. Fifty years later this limit still applies to the majority of measurement made in EMAs and SEMs, even though there is often a need to analyze much finer structures. When high resolution chemical analysis is required, it is generally necessary to prepare thin sections and examine them in an analytical electron microscope where the maximum diameter of the excited volume may be as small as a few nanometers. Since it is not always possible or practical, it is important to determine just what is the best spatial resolution attainable for the examination of polished or “as received” samples with an EMA or SEM and how to achieve it experimentally.
Consistency Checks for X-Ray Microanalysis at Low KV
Authors: Statham Peter J 
Published: July 2020

Abstract
This work proposes a new consistency check total based on measurement of bremsstrahlung intensity which can be used to validate analyses even when concentrations have been normalised to 100%.
If elemental content of a material is unknown, spectral peaks have to be identified, either interactively, or by automatic procedures. When peak overlap is severe (e.g. Si K/ Ta M / W M, Al K/Br L), it is easy for an element to be misidentified or missed altogether and at low beam kV, some elements will not even produce a characteristic line suitable for analysis. When element identification or quantification requires deconvolution of closely spaced lines, minor miscalibration or inaccurate peak modelling produces inaccurate peak area estimates, Ai, instead of true peak areas, Ai*, and consequently inaccurate concentration estimates, Ci*. A common consistency check is to confirm that the analysis total is close to unity:
Cryo-Em of Large Unilamellar Phospholipid Vesicles That Self- Assemble At a Critical Temperature
Authors: Talbot T , Booy F , Leapman R D , Gershfeld N L 
Published: July 2020

Abstract
The mechanism for assembly of membrane lipid bilayers in vivo is generally considered to occur on existing membranes which act as templates for the assembly process. Not presently understood is the source of the membrane template. A thermodynamic theory describing a spontaneous process for assembly of unilamellar vesicles with properties of a critical state (1,2) has been tested in this study. The spontaneous formation of large unilamellar vesicles (LUV’s) from phospholipid components of cell membranes at a critical temperature T* has now been documented by cryo-electron microscope studies using aqueous dispersions of dimyrystoylphosphatidylcholine (T* = 29°C), and the total lipid extracts of E. coli membranes cultured at 32°C (T* = 32°C). The lipids were incubated at temperatures below, at and above the critical temperatures for LUV assembly. in conformity with thermodynamic theory, and other physical measurements that indicate unique bilayer properties exist at T* (3-5), LUV’s are seen to form only at T*.
A Time-Sectioning Cryo-Field Emission SEM (Cryo-Fesem) Study of Film Formation in Structured Latex Coatings
Authors: Ma Yue , Scriven L E , Davis H T , Erlandsen S L 
Published: July 2020

Abstract
Structured latex coatings find such applications as specialty paints, micro- and ultra-filtration membranes, templates for synthesizing inorganic complementary structures, and embedding media for whole-cell based bioreactors. to control well the microstructure and other properties of the final coatings requires understanding the film formation process that transforms a deposited layer of colloidal particles of polymer into a coherent solid coating as it dries, usually in air. This process cannot be visualized by light microscopy techniques when the latex particles are a few hundred down to a few tens of nanometers in size, as is normally the case. Conventional electron microscopy requires too high vacuum for liquid samples to survive. Environmental scanning electron microscopy tolerates modest partial pressure of solvent but is limited to a coating’s top surface and at low resolution. What is needed is to observe the interior of a drying, hydrated coating at nm-resolution. Cryo-SEM is a powerful means of studying microstructure evolution throughout a coating’s thickness in the wet and moist stages of film formation.
Versatile and Inexpensive Specimen Holder for High Angle Azimuth Rotation in a Low Temperature Scanning Electron Microscope
Authors: Wergin William P , Erbe Eric F , Ochoa Ronald 
Published: July 2020

Abstract
Low temperature scanning electron microscopy (LTSEM) avoids many of the artifacts associated with chemical fixation, dehydration and critical point drying. As a result, this technique has had numerous applications ranging from biology to hydrology. Unfortunately, experiments using LTSEM are frequently compromised by the limited sample manipulations that are available on most cryo-stages and by the cost of specimen holders. Whereas the conventional SEM stage enables 360° rotation and tilts as great as 90°, the braids or hoses required for cooling a cryo-stage generally limit rotation to about 30° and tilt to less than 40° from normal. Furthermore, the specimen holders for LTSEM may cost several hundred dollars each, thereby prohibiting experiments that require numerous holders. This study describes an inexpensive specimen holder that solves these problems.
Figure la illustrates a drawing of the specimen holder supplied with the standard transfer device from the Oxford CT 1500 Cryotrans System.
Cryo - Fesem of Subcellular Organisation Using an In-Lens Rod with A Vacuum Transfer System
Authors: Allen Terry , Rutherford Sandra , Bagley Steve , Morrison Bob , Goldberg Martin 
Published: July 2020

Abstract
The recent increase in use of Field Emission Scanning Instruments in biology has shown the potential of these systems for sub-cellular imaging, as they essentially provide transmission EM levels of resolution for surface imaging. in structures lacking inherent contrast in thin sections, such as nuclear pore complexes,(NPC) high resolution surface imaging has provided significant complementary structural information to the macromolecular architecture of the NPC. (Goldberg and Allen, 1996). A series of intermediate structural forms of the NPC during its formation has also been described using FESEM, which would not have been resolvable in TEM.(Goldberg, Weise, Allen, Wilson, 1997). All this work was performed with chemical fixation, dehydration and critical point drying, followed by high resolution Chromium coating. We now are extending these studies to a cryo-preservation approach, mindful of the requirement of rapid freezing to preserve the more labile events of membrane dynamics, and also to circumvent the requirement to expose membranes to organic solvents during conventional dehydration.
Preservation of Articular Cartilage for Electron Microscopy
Authors: ap Gwynn Iolo , Richards Geoffery , Wade Stephen 
Published: July 2020

Abstract
Water makes up 60-80% of the wet weight of articular cartilage. The remaining parts of this tissue are made up of a variety of cells, generally referred to as chondrocytes, and an extracellular matrix of, collagen fibrils (types II, IX and XI), proteoglycans. The collagens and proteoglycans, with associated water, are assembled into a structure that is capable of withstanding considerable loading.
The micro-structure of adult rabbit articular cartilage has been described, based upon ultrastructural studies. The tissue is arranged into zones, mainly based on the general orientation of collagen fibrils (See Figure 1). The collagen framework in the radial zone forms a continuous area of radially oriented and tightly bound collagen fibrils, in which are embedded at regular interval, tubular inclusions of proteoglycans (Figure 2). in rabbit tibial plateau tissue these inclusions have diameter of 1-3 fim and can be continuous from the calcified to the tangential zone.
Cryo-SEM and TEM of High Pressure Frozen Cells - Some Technical Contributions
Authors: Walther Paul 
Published: July 2020

Abstract
Imaging of fast frozen samples is the most direct approach for electron microscopy of biological specimen in a defined physiological state. It prevents chemical fixation and drying artifacts. High pressure freezing allows for ice-crystal-free cryo-fixation of tissue pieces up to a thickness of 200 urn and a diameter of 2 mm without prefixation. Such a frozen disc, however, is not directly amenable to electron microscopic observation: The structures of interest have to be made amenable to the electron beam, and the structures of interest must produce enough contrast to be recognized in the electron microscope. This can be achieved by freeze fracturing, cryo-sectioning or freeze substitution.
The figures show high pressure frozen bakers yeast saccharomyces cerevisiae in the cryo-SEM (Figures 1 and 2) and after freeze substitution in the TEM (Figure 3). For high pressure freezing either a Bal-Tec HPM 010 (Princ. of Liechtenstein; Figures 1 and 2), or a Wohlwend HPF (Wohlwend GmbH, Sennwald, Switzerland; Figure 3) were used.
Negative Stain Electron Microscopy (EM) of Baculovirus Cultureassembled Virus Capsids
Authors: Humphrey Charles D 
Published: July 2020

Abstract
Caliciviruses (CacV) including Norwalk like virus and Sapporolike virus, papillomaviruses (PapV, and parvovirus B19 (B19V) are infectious viruses known to cause a variety of diseases. These viruses are distinctive because of their low titers in body fluids and fastidious nature to culture, making them difficult to detect by EM or serology. The genomes of several CacVs, PapVs, and B19Vs have been characterized facilitating expression of specific proteins via recombinant technologies. Recombinant proteins may be useful for obtaining the antibodies to be used in improved immunoassays and vaccines for preventing diseases associated with these viruses. CDC and Emory University investigators have designed techniques by which capsid proteins for a variety of viruses including CaCV, PapV, and B19V were expressed in Autographies califomicanuclear polyhedrosis virus (AcNPV) infected Spodoptera fruigiperda (Sf9) cells. Those proteins self-assembled into virus-like particles (VLPs)(Figs.l- 4). Culture-expressed capsids were “purified” and concentrated by traditional protein purification techniques including gel filtration, sucrose gradient centrifugation and cesium chloride gradient centrifugation.
Characterization of Novel Yeast Endosome to Vacuole Mutants by Electron and Fluorescent Microscopy
Authors: Pinho M , Gharakhanian E 
Published: July 2020

Abstract
The vacuole of yeast, Saccharomyces cerevisae, is equivalent to the mammalian lysosome. Several genes and gene products have been identified in the vesicular transport of soluble hydrolases to the vacuole via an endosomal compartment. This postendosomal stage of vacuolar trafficking delivering biosynthetic, endocytosed, and autophagic/Cvt cargo specifically to the vacuole remains one of the least defined stages of vesicular transport. We have previously developed an immunological screen for mutants that internally accumulate a pre-vacuolar intermediate of the vacuolar protease, Carboxypeptidase Y (CPY), in a PEP4-independent manner while exhibiting normal secretion phenotypes. We hypothesize that such mutants would be defective at endosome to vacuole step of delivery, hence env mutants. in order to morphologically characterize our novel set of mutants we performed electron, fluorescent and Nomarski microscopy analysis.
Preliminary studies revealed pleiotrophic phenotypes with respect to vacuole structure by Nomarski and fluorescent microscopy. FM-464 uptake and staining assays shows punctate staining throughout the cell in mut79 and mut72.
Low Voltage Scanning Electron Microscopy
Authors: Joy David C , Newbury Dale E 
Published: July 2020

Abstract
Low Voltage Scanning Electron Microscopy (LVSEM), defined as operation in the energy range below 5keV, has become perhaps the most important single operational mode of the SEM. This is because the LVSEM offers advantages in the imaging of surfaces, in the observation of poorly conducting and insulating materials, and for high spatial resolution X-ray microanalysis. These benefits all occur because a reduction in the energy E0 of the incident beam leads to a rapid fall in the range R of the electrons since R ∼ k.E0 1.66. The reduction in the penetration of the beam has important consequences. Firstly, volume of the specimen that is sampled by the beam shrinks dramatically (varying as about E0 5 ) and so the information generated by the beam is confined to the surface of the sample. Secondly, the yield 8 of secondary electrons is increased from a typical value of 0.1 at 20keV to a value that may be in excess of 1.0 at 1keV.
3d Visualization Tools
Authors: Dougherty Matthew T 
Published: July 2020

Abstract
The tutorial presents 3D visualization as implemented at NCMI: beginning with a brief overview of the history and philosophy of scientific visualization, proceeding to a description of general methodologies used throughout the field of visualization, and concluding with specific applications in electron microscopy, confocal microscopy and x-ray diffraction. The majority of the tutorial uses biological examples of visualization to demonstrate concepts and tools.
History and Philosophy: Effective scientific visualization presents data in a simple, accurate conceptual formulation. Over the last one hundred years there has been a sea change in its economics caused by digital computers: beginning with calculated tables that were manually plotted, proceeding to two dimensional image graphics, and most recently multivariate 3D interactive graphics. The capability of scientific visualization has been greatly facilitated by the evolution of computers; particularly over the last ten years the 3D visualization of biological structures is quickly becoming a necessity for analysis, conceptualization, and presentations.
X-Ray Microanalysis of Materials in the ESEM or VP-SEM
Authors: Gauvin Raynald 
Published: July 2020

Abstract
When performing X-Ray microanalysis in the ESEM (Environmental Scanning Electron Microscope) or in the VP-SEM (Variable Pressure Scanning Electron Microscope), the operating conditions of the microscope must be optimized. This is to reduce the beam broadening of the incident electrons when they scatter with the gas molecules before entering into the specimen. As a result of this scattering, the incident beam is composed of two parts. The first part of the beam is the unscattered beam and the second part is the scattered beam, named the skirt. in high pressure and long working distances conditions, the diameter of the skirt may extend to several millimeters. in order to show the effect of the skirt on X-Ray generation, a copper strip was placed.5 mm away of the electron beam on a flat Al specimen. The peak to background ratio of the copper line was measured at different pressure (from 25 to 200 Pa) for Air as gas.
Microcharacterization of Induced Electric Fields in Poorly Conducting Specimens Irradiated in an Environmental Scanning Electron Microscope
Authors: Stevens-Kalceff Marion A 
Published: July 2020

Abstract
In a conventional scanning electron microscope, a thin, grounded conductive coating is applied to specimens that are poor electrical conductors to prevent retarding and deflection of the incident electron beam. in a variable pressure or environmental scanning electron microscope (ESEM), excess charge on the surface of uncoated poorly conducting specimens is balanced using ionized environmental gas. Ionized gas in environmental mode and grounded conductive coatings in conventional or high vacuum mode minimize charging at the specimen surface, however significant charge trapping may still occur in the implanted sub-surface regions of poorly conducting materials. A small fraction (&lt;10-6) of the incident electrons are trapped at irradiation induced or pre-existing defects within the irradiated specimen. The trapped charge induces a highly localized electric field which can result in electro-migration and micro-segregation of charged mobile defect species within the irradiated micro-volume of specimen.
Time Dependent Study of the Positive ion Current in the Environmental Scanning Electron Microscope (ESEM)
Authors: Morgan SW , Phillips MR 
Published: July 2020

Abstract
The Environmental Scanning Electron Microscope (ESEM) is capable of image generation in a gaseous environment at sample chamber pressures of up to 20 torr. in an ESEM, low energy secondary electrons emitted from a sample surface, by virtue of the primary electron beam, are accelerated towards the positively biased metallic ring (typically +30 to +550V) Gaseous Secondary Electron Detector (GSED). As these electrons accelerate towards the ring they undergo ionizing collisions with gas molecules producing positive ions and additional electrons known as environmental secondary electrons. The environmental electrons further ionize the gas on their way to the ring producing a cascade amplification of the original signal. The amplified signal induced in the ring is used to form an image. The electric field generated between the GSED ring and the grounded stage causes the positive ions produced in the cascade to drift towards the sample, effectively neutralizing negative charge build up on the surface of a non-conducting sample.