bluuebunny/crossref_metadata_2025 huggingface dataset:
Autoschizic Death of Human Ovarian Carcinoma (MDAH 2774) Cells: LM and SEM Aspects
Authors: Gillotcaux J , Jamison JM , Arnold D , Von Greunigen V , Summers JL
Published: July 2020

Co-administration of Vitamin C (VC) and Vitamin K3 (VK3) combination (in a VC/VK3 ratio of 100:1) to several human carcinoma cell lines resulted in equivalent antineoplastic activity at concentrations that were 10-50 times lower than when either vitamin was administered alone. Peroxides generated by VC resulted in membrane lipid alteration. VC and VK3 combination resulted in cytoskeletal alterations, DNAses and RNase activation. This report documents LM and SEM morphological changes of ovarian carcinoma cells which accompany vitamin treatment and lead to autoschizic cell death.

MDAH cells were cultivated in titer dishes and on coverslips coated with polylysine. After exposure to either VC, VK3, or the VC/VK3 combination for 1 hour, cells on coverslips were fixed and processed for SEM. Cells in dishes (105 cells) were harvested, centrifuged (<500 r/min), fixed and embedded in PolyBed. Sections, oneurn thick, were stained by Toluidine blue prior to LM and TEM studies.
The Use of Accurate Morphologic Criteria to Diagnose Chemically Induced Lung Tumors in the Mouse is Essential for Extrapolation of Molecular Data When Applied to the Study of Human Disease
Authors: Gunning WT
Published: July 2020

Lung cancer remains the leading cause of cancer death in the United States. It has been estimated that in the year 2001 there will have be more than 157,400 deaths from lung cancer (28% of all cancer deaths) and 169,500 newly diagnosed cases of lung cancer (13.4% of all newly diagnosed cancer) recorded. The significance of this disease requires development of better treatments and of feasible means to prevent the development and progression of lung cancer, especially since the progression of initiation to clinical manifestation may take years. The use of an appropriate animal model is paramount to the study of human disease.

More than 95% of all primary human lung cancer is directly attributed to the use of tobacco products2. The most common forms of human lung cancer include squamous cell carcinoma, adenocarcinoma, and small cell carcinoma.
Detecting Early Apoptosis in Whole Epithelial Sheets with a Caspase 3 Substrate, Phiphilux and Annexes V Using Confocal Microscopy
Authors: Svoboda Kathy K H
Published: July 2020

Many reagents have been developed recently to label living cells with substrates that will become fluorescent if an enzyme is active. The general principle is that the substrate will be taken up by living cells then detected only if the enzyme is active. These substrates work well with isolated individual cells, however, more difficulty can be encountered when studying whole tissues. Problems can range from substrate penetration into whole tissues to being able to detect the label effectively. We have used the chicken corneal epithelia for many studies, but the tissue is to thick to view with a conventional light microscope, therefore we have developed techniques using laser confocal microscopes to view this tissue in with a variety of techniques including in situ hybridization, immunohistochemistry, and vital dyes/stains.

Whole embryonic corneal epithelial sheets can be isolated without the basal lamina.
Imaging and Flow Cytometry: Competing or Complementary Technologies?
Authors: Robinson JPaul
Published: July 2020

Introduction This presentation will follow the pathways to convergence of two very complementary technologies - flow cytometry and imaging. Interestingly, each technology has evolved and matured almost exclusively isolated from the other. in the past several years it has become increasingly clear that these technologies are able to deliver complementary solutions and that when combined the end value of each exceeds the sum of the individual components.

History of development Flow cytometry has a rich history over the past 40 years. Ironically, as a technology, flow cytometry was almost a consolation prize to its imaging cousins. in fact, it seems that it might only have been because imaging solutions proved to be technologically difficult that flow cytometry not only thrived, but left the imaging field well behind for nearly 20 years. Initial interest in evaluating differences between normal and cancer cells was almost exclusively attempted by imaging techniques.
Identification of MHC-I Accessible Proteins from Salmonella Typhimurium
Authors: Ellefson D , Parker D , Heffron F
Published: July 2020

Intracellular bacterial pathogens such as Salmonella typhimurium secrete proteins into the host cell after infection. These proteins alter the normal structural and metabolic machinery of the host cell and benefit the bacterium by facilitating replication and avoidance of host immune surveillance. Since the host cytoplasmic localization of these proteins infers access to the class-I MHC antigen processing and presentation machinery of the host cell, we collectively refer to these proteins as Class- I Accessible Proteins (CAPs).

The design of vaccines for new and emerging bacterial pathogens is often constrained by the selection of appropriate and specific antigens. While vaccine design is being greatly aided by whole genome analysis of bacterial pathogens, it has been of limited use in the assignment of function and host subcellular localization of a large percentage of bacterial proteins. in addition, analysis of the bacteria/host interaction is further complicated by the complex lifestyle of the pathogen.
Computer Assisted Morphometry: A Pathologist’s Perspective
Authors: Holland JM
Published: July 2020

In spite of improved equipment and software, the routine application of quantitative microscopy to practical problems in drug development has been limited. This is due to a perceived and often real increase in project complexity and time added by quantitation of tissue changes, without an offsetting return of information. A major barrier to quantitative microscopy is the degree of difficulty in collecting data. The more steps in this process, the less attractive the task. Therefore, it follows that the more automated the task, the more likely quantitative methods will be applied. The purpose of this presentation will be to illustrate an approach taken to automate the morphometric quantification of muscle atrophy which follows dennervation.

The traditional morphometric approach to assess myofiber atrophy is based upon laborious planometric measurement of individual muscle fiber cross-sections. Examples of the type of data obtained using the traditional method are shown in text table 1.
Microscopic Analysis of Oxidative Stress in Cultured Cells. II. Transmission Electron Microscopy
Authors: Gales Tracy L , Maleeff Beverly E , Narayanan Padma K , Tirmenstein Mark A , Hart Timothy K
Published: July 2020

The insulin-sensitizing agent troglitazone (Rezulin) has been shown to cause severe hepatotoxicity and liver failure. While the toxic mechanism is still unknown, a component may be oxidative stress. We have demonstrated that increased lipid peroxidation, decreased glutathione levels, and collapse in mitochondrial membrane potential occurred following exposure of cultured hepatocytes to troglitazone. These hallmarks of oxidative stress can manifest morphologically in several ways including damage to cellular membranes, mitochondrial abnormalities, and cell death. The purpose of this study was to assess morphologic changes caused by exposure to troglitazone or cumene hydroperoxide (CH), a compound known to induce oxidative stress.

HepG2 and Novikoff hepatoma cells were grown on poly-L-lysine coated 6-well plates overnight, and exposed to 10, 25, 50 or 100 μM concentrations of troglitazone or CH in the growth media for 2 hours. Cells were fixed with 2.5% glutaraldehyde in phosphate buffer, harvested, and pelleted. Pellets were post-fixed in 1% osmium tetroxide, and processed to epoxy resin.
Nuclear Channels in Hela Cells: Nucleocytoplasmic Transport or Reassembly of the Nuclear Envelope?
Authors: Palisano JR , Traister EK
Published: July 2020

Although nuclear channels (NC) have been described in a variety of cells, their function has not been fully investigated. This investigation used immunofluorescent techniques to examine the formation and function of NC in HeLa cells, a human cervical cancer cell line. NC are defined as invaginations of the nuclear envelope (NE) that traverse the nucleoplasm, thus forming a ring-like nucleus. The resulting tunnel is devoid of nucleic acid and may contain cytoplasmic elements. to date, all the reports of the presence of NC are from electron microscopic investigations, which clearly demonstrate the occurrence of NC in the presence of what appear to be interphase nuclei. This investigation was initiated because the NC that we observed in HeLa cells could be seen with fluorescent microscopy and only appeared during telophase and early interphase.

HeLa cells, obtained from American Type Culture Collection, were cultured on glass coverslips in minimum essential medium (MEM) containing 5% calf serum (CS) and a mixture of 5% CO2 in air at 37°C.
Identification of Scavenger Receptor Class B Type I in the Hepatocytes of Hypercholesterolemic Rats
Authors: Wang J Y , Lee Y W , Hsiao H Y , Chao W T , Yang V C
Published: July 2020

The levels of plasma high density lipoproteins (HDL) are inversely related to the incidence of atherosclerosis and coronary heart disease. This protective effect of HDL is thought to be involved in the reverse transport of cholesterol from peripheral tissue to the liver. The scavenger receptor class B type 1 (SR-BI) is the first HDL receptor that can mediate the selective uptake of HDL cholesterol in steroidogenic tissues and in liver. The expression of SR-BI in liver appears to be responsive to changes in the hormonal status and in the levels of HDL cholesterol. However, long-term effects of high-cholesterol diet on the SR-BI expression in liver parenchymal cells and KupfFer cells have not been studied. to investigate the in vivo effects of liver-specific SR-BI expression on lipid metabolism, we fed male Sprague-Dawley rats with high-cholesterol or normal diet for 1 and 12 months.
Enhancement and Co-Localization of Erk and Collagens in Human Myocardium with Congestive Heart Failure
Authors: Dong Y , Lin R , Wei C
Published: July 2020

Mechanical stimuli frequently trigger signals leading to increase gene expression, protein synthesis, or mitogenesis. Cardiac fibroblasts respond to changes in ventricular hemodynamic loading by increasing matrix production in models of pressure-overload hypertrophy and myocardial infarction. Recent studies have identified some of the intracellular signaling pathways that mediate the biological effects observed upon mechanical stimulation in vitro. These include mitogenactivated protein kinases (MAPKs) and protein kinase C (PKC) family. MAPKs include extracellular signal-regulated kinase (ERK), C-Jun NH2-terminal kinase (JNK), and p38 MAPK. ERK pathway is frequently stimulated in response to mitogen.

Previous studies demonstrated that mechanical stretch stimulated MAPK activities in normal adult rat cardiac fibroblasts. On the other hand, mechanical stretch also increases transcription and production of the matrix proteins collagen (type I and HI) and fibronectin in cardiac fibroblasts. MAPKs are activated by mechanical stretch during cardiac myocytes hypertrophy through both PKCdependent and independent pathways.
Surface Ultrastructural Effects of Fumagillin on Cultured Cancer Cell Lines
Authors: Majumdar S K , Marc C , Ruddy J
Published: July 2020

Fumagillin, an antibiotic isolated from the fungus Aspergillus famigatus and first utilized in the 1950’s for its antiprotozoal and antiamoebic properties, has recently been discovered to be a potent inhibitor of blood vessel growth, termed angiogenesis. A previous study indicated that fumagillin was toxic to murine erythroleukemic cells (MEL BB-88) and HeLa cervical carcinoma cells. This study was initiated to understand what effects the chemical has on the cell surface ultrastructural morphology of these two cancer cell lines.

MEL BB-88 cells were treated with 0.0, 5.0, or 10.0 μg/ml fumagillin for 24, 48, 72, and 96 hours, while HeLa cells received 0.0, 1.0, or 5.0 μg/ml fumagillin for the same time periods. Cells were fixed in 2% glutaraldehyde for two hours, postfixed in 1% osmium tetroxide for one hour, dehydrated in an ascending alcohol series, critically point dried, coated with gold palladium, and observed under an ISI Super III scanning electron microscope
Postischemic Morphological Changes of the Dentate Gyrus in the Gerbil During Reperfusion
Authors: Yu SM , Wang JC
Published: July 2020

Postischemic lesion following reperfusion have been investigated in the gerbil by temporary occlusion of a common carotid artery. Two phenomena have been reported in injured ischemic cells: the inability to restore mitochondrial function and evidence of plasma membrane damage. For Further understanding the pathophysiological mechanism of ischemic lesion, we have evaluated the various ischemic period and early postischemic reperfusion. in addition to the morphological changes of the dentate gyrus by light microscopy, we employed the immunocytochemical staining for iNOS and eNOS.

The mongolian gerbil, Meriones unguiculatus, were anesthetized with α-chloralose (350mg/kg), bilateral common carotid artery occlusion was induced for 90 minutes. The right common carotid artery was ligated with 5-0 silk suture, and the left was clamped by a micro vascular/miniature aneurysmal clip. After an ischemic period of 90 minutes, restoration of the blood flow of the left common carotid artery was accomplished by withdrawing the microvascular clip.
Propagation of Errors in the Precision and Accuracy of Quantitative Electron Microbeam Analysis
Authors: Armstrong J T
Published: July 2020

A common question, but one typically difficult to answer, is “How accurate is a microprobe or SEM analysis?” Commercial software for most EDS and WDS systems print out error limits that are typically calculated standard deviations using Gaussian counting statistics based on the accumulated peak and background counts. This is not a true measure of even the measurement precision, since random instrumental instabilities typically degrade “true” measurement precision (as determined by replicate measurements on standards) to 1.5 - 3+ times that predicted from Gaussian statistics. in addition to these random instrumental variations are a plethora of possible systematic and semirandom errors such as detector or faraday cup non-linearities, errors in estimation of background, EDS spectral deconvolution errors, WDS positional non-reproducibility, temperature and pressure variation effects on spectrometer efficiencies, high voltage drift or sample charging, surface contamination or oxidation, and sample roughness or tilt.
Ionization Cross Sections for Quantitative Electron Probe Microanalysis
Authors: Merlet C , Llovet X , Segui S , Fernández-Varea JM , Salvat F
Published: July 2020

Quantitative procedures in electron probe microanalysis (EPMA) require the knowledge of various atomic parameters, the most fundamental of which is the ionization cross section. A number of semi-empirical, approximate analytical formulas have been proposed to calculate the ionization cross section. The simplicity of these formulas makes them suitable for quantitative EPMA procedures. However, it is difficult to assess their reliability because of the lack of accurate experimental data. Indeed, inspection of currently available data reveals that they are still scarce for many elements and, when they are available, one usually finds significant discrepancies between data from different authors. Fortunately, the inaccuracies in the semi-empirical cross section formulas used in EPMA have only a small effect on the analytical results when standards are used. Nonetheless, in quantitative EPMA studies at low overvoltages or using standardless methods, the evaluated compositions largely depend on the adopted ionization cross sections and, therefore, knowledge of accurate ionization cross sections is a requisite for the development of improved quantification methods.
X Ray Spectra Simulation For Wds : Application to Electron Microprobe Automation
Authors: Fournier C , Staub P-F , Merlet C
Published: July 2020

Experimental conditions and setting up of an electron microprobe is directly linked to the assumption or the knowledge that can make the operator on the results of the measurements. Consequently, there is an increasing interest in modelling the X-ray spectrum in order to predict accurately and rapidly the response of the microprobe when a sample of approximately known composition is submitted to specific excitation conditions. Even if the spectra simulation is a current tool proposed in EDS, it always remains a challenge to create a complete absolute WDS spectrum. Indeed, the definition of the efficiency function was a limit to the calculation of absolute intensities.

In this work, we propose a new generation software for EPMA which uses the absolute simulation spectra to assist the operator in the choices of experimental conditions to achieve accurate measurements in a short time as well as to create new functionalities.
Application of Alpha-Factor and Monte Carlo Methods to Epma in the System Ge-Si
Authors: Carpenter P , Cobb SD
Published: July 2020

Terrestrial experiments involving detached growth of GeSi crystals by the Bridgman technique have been performed in preparation for microgravity experiments to be conducted on the International Space Station. These experiments typically produce large GeSi crystals that are sectioned for microscopy, microprobe analysis, and electron-backscatter diffraction analysis. Accurate microanalysis of these crystals is essential for feedback to further growth experiments, but is problematic as the Ge-Si binary exhibits continuous solid solution and it is therefore difficult to prepare homogeneous intermediate standards. There are no experimental measurements on standards of known composition in the Ge-Si binary that could be used to evaluate analytical accuracy. The accuracy of analysis in mineral, oxide, and semiconductor systems has previously been studied using experimental x-ray intensity measurements, correction algorithms and their derived α-factors, and mass absorption coefficient data sets. This study continues that approach and includes results of Monte Carlo calculations in the Ge-Si binary.
Applications of Monte Carlo Simulation of Electron Scattering to Quantitative X-Ray Microanalyses
Authors: Murata Kenji , Yasuda Masaaki , Yamauchi Syunji
Published: July 2020

Monte Carlo simulation of electron scattering has been widely used in various fields such as microanalysis, microscopy and microlithography. Various simulation models have been reported so far. in applications to quantitative x-ray microanalysis the accuracy of the model has been significantly improved by introducing the Mott cross section. However, in the analyses at low energies of an electron beam or at energies near the x-ray excitation energy, the simulation accuracy becomes worse. This is probably because the discrete energy loss process is not incorporated into the simulation model. to improve this default, we developed the model which includes the discrete energy loss process[l]. The outline of the model is described in the following.

1) Elastic scattering

We used the Mott cross section. The Mott cross sections for Al, Cu, Ag and Au elements are calculated at various energies. From this data base we obtain the differential elastic scattering cross section and the total elastic cross section for arbitarary elements and energies by using the interporation or the extrapolation.
Effects of Charging on Quantitative X-Ray Microanalysis Procedures in Environmental / Variable Pressure SEM
Authors: Griffin Brendan J , Suvorova Alexandra A
Published: July 2020

In variable pressure (VPSEM) and environmental SEM (ESEM) caution is required in the intepretation of x-ray data from non-conductive and electrically isolated samples for unique reasons. This paper reviews the documented procedures and presents data on hither-to undefined aspects.

The most widely recognised artefacts are associated with the scatter of primary electrons from their convergent trajectory to the sample surface through interactions with the chamber gas. Beam ‘skirt’ measurements have been made by various researchers and this scatter is well characterised. “Point” analyses are corrupted by addition of components from the surrounding phases and x-ray maps are effectively ‘defocussed’ or ‘blurred’. The magnitude is a function of pressure, amongst many other variables, and it has been shown that these scatter effects can be reduced through extrapolation of data collected at differing chamber pressures2. Bremsstrahlung-based corrections for primary beam variations and drift have also been shown to be effective.
X-Ray Microanalysis of Human Erythrocytes Artificially Jetted Through Tubes At Different Pressures by “in vitro Cryotechnique”
Authors: Fujii Y , Terada N , Baba T , Ueda H , Ohno S
Published: July 2020

It is well known that flowing erythrocytes in blood capillaries were morphologically changing in vivo, as observed by light microscopy. Recently, dynamic morphological changes of flowing mouse erythrocytes in large blood vessels and hepatic sinusoids were demonstrated by scanning (SEM) or transmission (TEM) electron microscopy with our “in vivo cryotechnique”. Moreover, human erythrocyte deformability was already studied under artificially jetting conditions at different pressures by using “in vivo cryotechnique”, followed by freeze-substitution method for SEM. in this study, we have analyzed elemental changes of each human erythrocyte at different jetting pressures by “in vivo cryotechnique” combined with SEM for X-ray microanalysis.

Human blood was collected with heparin-coated syringes, divided into two groups and kept at 4°C and 36°C. They were directly jetted into isopentane-propane cryogen (-193°C) through tubes (21 gauge) at different pressures (0-220mmHg) (Fig.la). The frozen blood samples were freeze-dried (4-6×10-7torr,-95°C,24h) in Eiko FD-3AS apparatus (Eiko Engineering, Japan) (Fig. lb).
A Pre-Golgi Copartment Connecting Golgi Cisterns to the Perinuclear Space in Bovine Herpesvirus 1 (Bhv-1) Infected Mdbk Cells. Evidence for an Intracisternal Pathway
Authors: Wild P , Schraner EM , Cantieni D , Engels M , Loepfe E , Walther P , Müller M
Published: July 2020

The nucleocapsid of herpesviruses is assembled within the nucleus and transported to the perinuclear space by budding through the inner nuclear membrane. The route from the perinuclear space to the plasma membrane for exocytotic release is assumed to involve loss of the acquired envelope by fusion with the outer nuclear membrane followed by wrapping of the nucleocapsid by Golgi membranes. Alternatively, virions are thought to leave the perinuclear space via vacuoles originating from the outer nuclear membrane. Non of these processes has been shown so far. We thus examined the nuclear periphery of MDBK cells infected with BHV-1 by cryobased electron microscopy. Infected cells were high-pressure frozen at 4, 5 and 6 hours of incubation, and freezesubstituted employing a protocol yielding high resolution of membranes.

Thin sections stained with uranyl acetate and lead citrate showed 3 distinct stages of viral envelopment at any time of incubation.
Ultrastructural and Cytochemical Analyses of the Expression of the Thiobacillus Carboxysome Operon in Escherichia Coli
Authors: Aldrich HC , Elvington S , Machines HE , Szabady R , Feder K , McDowell L , Shively JM
Published: July 2020

The cytoplasm of the bacterium Thiobacillus neapolitanus contains 117 nm diameter polyhedral inclusions, “carboxysomes” (Fig. 1) that contain ribulose-1,5- bisphosphate carboxylase/oxygenase (RuBisCO). Surrounding the polyhedron are nonmembranous proteinaceous plates devoid of lipid. The carboxysomes are composed of at least 8 major peptides, all coded within the same operon. Six (CsoSIA, CsoSIB, CsoSIC, CsoS2A, CsoS2B, and CsoS3) make up the shell, and two are the large (CbbL) and small subunits (CbbS) of RuBisCO. Using immunogold labeling on ultrathin sections, peptides CsoS2A, CsoS2B, and CsoS3 have been localized to the shell. Since the original characterization of the csoSl gene, we have also immunolocalized the CsoSl peptide to the shell.

As part of our initial efforts to understand how these components are assembled into the symmetrical, functional entity, the carboxysome operon from T. neapolitanus was cloned into the pET-21a(+) plasmid, an expression vector that codes for resistance to ampicillin.
A New Smaller Sized Virus-Like Particle in Drosophila Melanogaster
Authors: Ault Jeffrey G , Shimakawa Ellen
Published: July 2020

During a chromosome behavior study involving high-pressure freezing (HPF)/freeze substitution (FS) of Drosophila melanogaster testes, we discovered quasi-crystalline inclusions in the nuclei of adjacent gut epithelial cells (Fig. 1). The HPF and FS protocols were standard. The viscera of adult flies were packed in yeast paste for HPF. The tissue was fixed by FS with 1% osmium tetroxide in acetone for 72 hours at -90° C then 48 hours at -60° C. Afterwards, it was washed several times at room temperature in 100% acetone and embedded in Epon/Araldite. Thin sections were cut and stained with uranyl acetate and lead. As expected with HPF/FS, the material was well-preserved with straight microtubules, smooth membranes, dense mitochondria, and abundant ribosomes both on the rough endoplasmic reticulum and in the full cytoplasm (Fig. 1).

The inclusions consisted of virus-like particles packed loosely together in orderly arrays. Particles were usually hexagonally packed with spaces disrupting the periodicity (Figs. 2 and 3).
The Structure of Ppv0l, A Marine Algal Virus with a T=219 Capsid
Authors: Yan X , Chipman P , Castberg T , Bratbak G , Baker T S
Published: July 2020

Phaeocystispouchetii virus (PpV0l), first isolated from Norwegian coastal water in 1995, infects and lyses the haptophyte Phaeocystis pouchetii Lagerheim. PpV0l has not yet been assigned to a family. Phaeocystis may play an important role in ocean climate control and PpV0l infection could alter the amount of this haptophyte. The virion contains a dsDNA genome (∼450 kbps) encapsulated within a large icosahedral shell. The most abundant protein has a mass of 59 kDa. More than five minor polypeptides with masses ranging from 30 to 50 kDa have also been identified. We have used cryo-electron microscopy (cryo-EM) and three-dimensional (3D) image reconstruction methods to examine the native morphology of PpV0l.

Purified PpV0l samples were prepared for Cryo-EM as described. Images were recorded on film at 33,000x nominal magnification in a Philips CM300 FEG microscope at 300kV, at 1.0μm to 2.0μm under focus, and with an electron dose of 2200e-/nm2 (Fig. 1A).
Detecting Herpesvirus By Negative Contrast Electon Microscopy in Tissue and Cell Culture From Mule Deer with Infectious Keratoconjunctivitis
Authors: Hearne CE , Cavender JL , Williams ES
Published: July 2020

Mule deer are infected with a herpesvirus associated with acute infectious keratoconjunctivitis (IKC) or “pink eye”. in December 2000, many young male mule deer in Wyoming had clinical signs of IKC including corneal edema, mucopuvulent conjuctivitis, blepharospasm, and blindness.

Conjunctival swab samples from 5 mule deer with IKC were processed for negative contrast electron microscopy (NCEM) at the Wyoming State Veterinary Laboratory (WSVL). Homogenized samples from each deer were centrifuged for 20 minutes at 3440g in a Beckman Avanti J-25 centrifuge (Beckman Instruments Inc., Fullerton, CA, USA). The supernatant from each sample was subsequently centrifuged for 60 minutes at 39,800g. The final pellet was resuspended in 210 μl of sterile deionized microfiltered water. 105 μ1 of the virus suspension was mixed with sodium phosphotungstic acid stain containing 84 μl of 4% aqueous phoshotungstic acid, pH 6.8 with NaOH, 420 μl sterile, deionized microfiltered water, and 21 μl 0.1% bovine serum albumin.
Blomineral Compartmentalization in Uncultured Magnetic Bacteria
Authors: Lins Ulysses , Keim Carolina N , Farina Marcos
Published: July 2020

Magnetic bacteria are a group of motile microorganisms that orient to magnetic field lines because of membrane-bound organelles called magnetosomes. Magnetic bacteria precipitate magnetite (Fe3O4) or greigite (Fe3S4) in their magnetosomes. The ability of uncultured magnetic bacteria of accumulating minerals in different cell compartments is still poorly understood. We have been studying natural enrichments of magnetic bacteria from the Itaipu and Rodrigo de Freitas lagoons, in Rio de Janeiro, Brazil. Here, we have used energy-filtering transmission electron microscopy to study the element distribution in biocomposites found in magnetic bacteria from both lagoons. in Itaipu lagoon, electron microscopy and phylogenetic position determination by 16S rRNA genes sequencing identified at least four morphotypes of magnetic bacteria. Typical structures found in all gram-negative bacteria, in addition to some internal compartments were observed (Fig. la). Amorphous granules (Fig. la) and magnetosomes (Fig. lb) were the two well-defined compartments that accumulated significant amounts of minerals.
Running a Multi-Purpose Microscopy Laboratory
Authors: Nockolds C E
Published: July 2020

Multi-purpose microscopy laboratories can be found in a number of different places, including industry, hospitals, government research organizations and universities and the set up and operation of such a laboratory may well be quite different in each of these environments. in this tutorial the issues that are important in the running of a microscopy laboratory will be explored. The main topics include fundamental questions such as whether it is a good idea to have a centralized unit in the first place, how the operation of the laboratory should be funded and what the mix of staff and equipment should be.

Before we talk about how to run a multi-purpose laboratory we should consider the merits of having such a laboratory in a particular institution and whether that unit should be “centralized”. By centralized I mean that it is the preferred option for the institution to have most of the equipment in a central laboratory where it is essentially available to all the interested groups in the organization.
Topics in Electron Diffraction (TEM): A Tutorial
Authors: Eades J A
Published: July 2020

Introduction. Electron diffraction is sometimes considered to be a “difficult subject”. It is certainly one that can not be covered in the space available here. Rather this tutorial will present a few specific aspects of the topic. The topics have been chosen in the hope that they will provide illumination that spreads more widely than just onto the material presented. Several books treat electron diffraction with more generality.

Kikuchi lines Kikuchi lines are of great use in orienting a sample. Unfortunately, in modern microscopes, Kikuchi lines are not seen in selected-area diffraction (SAD). This is because immersion lenses send parallel electrons, from different parts of the sample (like the Kikuchi lines from a flat specimen), to different places in the diffraction pattern. Thus Kikuchi lines are blurred and generally not useful whenever, as in SAD patterns, a large area of the sample contributes to the diffraction pattern.
A History of ESEM in 2.5 Chapters
Authors: Kersker Michael M
Published: July 2020

Microscopy has always been concerned with the observation of samples in their natural states. The earliest instruments, optical microscopes, did not interfere with the samples which were under observation due to the pervasive presence of visible light in the normal evolution of these entities. Man and science persisted in this direction until Ruska in 1933 invented the electron microscope and the real world changed forever (see MSA Rudenberg for an enlightening description of the early days of man's understanding of the electron and the subsequent invention of the electron microscope). The earliest electron beam instruments were single vacuum chamber entities. As single chamber designs, every element in the optical path was under vacuum. These included the electron gun, the lens and coils, recording film, and of course, the specimen itself. The purpose of the vacuum was quite obvious...to eliminate the scattering of the electrons due to the presence of gas.
Analysis of Interesting Materials in the Environmental SEM: You Put What in Your Microscope?
Authors: Mansfield John F
Published: July 2020

The environmental scanning electron microscope (ESEM™) and variable pressure electron microscope (VPSEM) have become accepted tools in the contemporary electron microscopy facility. Their flexibility and their ability to image almost any sample with little, and often no, specimen preparation has proved so attractive that each manufacturer of scanning electron microscopes now markets a low vacuum model.

The University of Michigan Electron Microbeam Analysis Laboratory (EMAL) operates two variable pressure instruments, an ElectroScan E3 ESEM and a Hitachi S3200N VPSEM. The E3 ESEM was acquired in the early 1990s with funding from the Amoco Foundation and it has been used to examine an extremely wide variety of different materials. Since EMAL serves the entire university community, and offers support to neighboring institutions and local industry, the types of materials examined span a wide range. There are users from Materials Science & Engineering, Chemical Engineering, Nuclear Engineering, Electrical Engineering, Physics, Chemistry, Geology, Biology, Biophysics, Pharmacy and Pharmacology.
Charge Contrast Imaging (CCI) in the Environmental Scanning Electron Microscope: Optimizing Operating Parameters for Calcite
Authors: Doehne Eric , Carson David
Published: July 2020

Charge contrast imaging (CCI) is a useful new method for imaging sub-micron features in crystalline materials using the unique gas/ion/electron imaging system of the environmental scanning electron microscope (Griffin, 1997; Doehne, 1998). Crystal growth zoning, microfractures, solution boundaries, and areas of chemical alteration or recrystallization can be imaged in a wide range of materials (Griffin, 2000; Watt, et al. 2000). While not fully understood, charge contrast images reflect differences in the ability of materials to accept, store and discharge deposited electrons from the primary electron beam. These differences are expressed, in turn, as contrasts in secondary electron emission from flat samples (e.g. these contrasts are not related to topography, as is usually the case). Charge contrast appears be related to differences in electronic properties which are often controlled by defect density. CCI is also affected by small-scale physical defects (such as microfractures) which appear to affect the distribution and timing of charge buildup and discharge in the sample (Johansen, et al. 1997).
Techniques and Applications for Imaging Biological Samples in a Low Vacuum Environmental Scanning Electron Microscope
Authors: Gilpin. C J
Published: July 2020

Of all the commercially available scanning electron microscopes which operate at “low vacuum” the ESEM is the most suitable for examining biological samples. in order to maintain samples with liquid water present the specimen chamber must be capable of operating at a pressure of at least 4.6 Torr (611 pascals) of water vapour pressure (the vapour pressure of water at 0°C). Use of lower pressures or a chamber gas other than water vapour will result in evaporation of water from the sample at a rate dependant on the partial pressure difference between the sample and its surrounding environment. Tables of relative humidity as a function of water vapour pressure and temperature are readily available to calculate desired settings for the microscope.

One of the difficulties associated with examining fresh biological material is the need to have the microscope and sample available in the same location at the same time.If sample collection occurs at a site remote from the microscope inevitable necrotic changes will occur before examination can be carried out.
Modifying an FESEM for Low-Vacuum Work
Authors: Ervin M H
Published: July 2020

Environmental SEM has greatly extended the utility of SEM as a result of an ESEM's ability to image volatile and insulating samples. However, many institutions have older high-vacuum SEMs that they cannot afford to replace with an ESEM. For this reason, a simple and inexpensive pressure cell has been developed for performing low-vacuum SEM in a standard microscope. Rather than backfilling the entire analysis chamber with gas, a small volume of higher pressure is confined at the sample surface with the use of a pressure cell that has a small aperture for admitting the primary beam and a gas inlet. Figure 1 is a photograph of such a simple pressure cell.

The aperture for admitting the primary beam needs to be small enough to limit the escaping gas to an amount below what the standard SEM can pump and still maintain high vacuum. On the other hand, the aperture should be as large as possible to provide a useful field of view.
Effects of Gaseous ion Concentration on Secondary Electron Contrast of Dielectric Materials Imaged in the ESEM
Authors: Thiel BL , Toth M , Craven JP
Published: July 2020

An increasing body of experimental evidence indicates that the flux and distribution of gaseous ions significantly affects secondary electron contrast of dielectric materials imaged in low vacuum and environmental scanning electron microscopes. Unusual contrast has been identified in some insulating materials, and attributed to charging effects (1-3). However, as these contrast mechanisms have not been reported in conventional microscopes, it would seem that the ions play an important role in making the contrast manifest. The effects of ions can include the creation of space charge in the gas above the specimen, influencing the charge state of the specimen surface, and electron-ion recombination (possibly leading to energy filtering of emitted secondary electrons). Space charge and surface potential can influence the gain realised in the gas amplification cascade by altering the detector field (4). However, surface potential, and recombination affect the number of electrons injected into the amplification cascade, to give rise to contrast variations in the final image.
Environmental Scanning Electron Microscopy of the Dehydration of Gel Materials
Authors: McKernan Stuart , Tankeren Robert van , Mayo Kevin H
Published: July 2020

The possibility of performing scanning electron microscopy under “environmental” conditions (ESEM); where the specimen does not have to be under high-vacuum conditions, or even coated to make it conductive, has existed for several years [1]. in particular it has been possible to image in conditions that allow the samples to remain fully hydrated during observation. This unique feature of the ESEM has been exploited to image the dehydration of aqueous protein gel materials which have been created under controlled conditions to produce a range of Gel types.

Drops of several μl of the Gels were placed in the Peltier cooling stage of the FEI-Philips Electroscan E3, and allowed to stabilize at 4.1°C. Several drops of water were placed on the stagesurround to maintain a high vapor pressure of water around the sample. The chamber was then pumped down to the working pressure of 6 torr and then back-filled with pure water vapor following the technique of Cameron et.al. [2].
The Development of Remote Teaching Aids
Authors: Chapman Stephen K
Published: July 2020

For many years the means of communicating electron microscopy techniques had been through either the spoken or the written word. with the advent of the computer and in particular the notebook computer more exotic methods of information presentation were made available. Now with the compact disk or the DVD, with their ability to store very large quantities of data, even more new avenues have been opened up for trainers.

There are a number of programs by small organisations, like QM Slide Show and EZ Slide, that enable the trainer to take the simple approach to presentation preparation. Using a Windows Notepad interface or similar the trainer gathers bitmap files in a simple sequence, referencing the file source to activate each part of the presentation. This type of presentation is extremely flexible, so much so that the trainer, with a large selection of bitmap files and a good filing system, may develop a completely new or modified presentation in just a few minutes.
Microscopy Education, not Just Training - Three sides of the coin
Authors: Foster Barbara
Published: July 2020

Two of the greatest challenges facing any educator are deciding what information will be included in a syllabus and how to present it for maximum learning. Distilling the experience derived from a quarter of a century teaching microscopy exposes one driving concept: the importance of education, not just training.

The difference between these two approaches is fundamental. Education involves laying a foundation on good science, building a vocabulary for better communication and future growth, and engendering a questioning attitude about the probe-matter interactions which, in turn, leads to valid interpretation of the information in an image. Training is a matter of learning what knob to turn, which button to push: an approach which overlooks the sample itself; how the light, electron, or scanning force is interacting with that sample; and what can be learned as a result.
Remote Access to an X-Ray Diffraction 'Collaboratory' for Research, Education and Training
Authors: Kantardjieff Katherine A
Published: July 2020

The W.M. Keck Foundation Center for Molecular Structure (CMolS) at California State University Fullerton is the first comprehensive x-ray crystallographic and computational facility located at a predominantly undergraduate institution. CMolS, a core facility of the California State University Program for Research and Education in Biotechnology (CSUPERB), engages more than thirty faculty and hundreds of student investigators throughout the 23-campus CSU in joint research and education activities directed at the determination and critical analysis of molecular structures. Recognizing that distance learning and remote access represent an exciting new area of research and training, CMolS has taken a leadership role in the CSU in using the Internet to restructure and globalize formal education in x-ray crystallography by developing and implementing novel Webbased courses, tutorials and virtual laboratories that require specialized instrumentation and expertise.

An NIH Structural Biology report and the Department of Energy [1] have indicated that high throughput crystallography is a top research priority in the post-genomic era.
Project Micro on Display At Sciencefest
Authors: Bell David C , Palmer Ann T
Published: July 2020

ScienceFest is coordinated through the International JASON Project that introduces the world of science through live satellite broadcasts. Dr. Robert Ballard, the ocean explorer who found the Titanic, started the program in 1989. Included in the ScienceFest presentations at the John Ford Bell Museum of Natural History, Project MICRO run by the Minnesota Microscopy Society (MMS) was on display to the public. As in past years [1] the Project MICRO team of the MMS set up various microscope stations and invited the participants to record the things that they saw and to note what they learnt and mention the things they would like to see. The microscope stations are quite simple, low power ‘field’ microscopes and various samples as documented by the “Microscopic Explorations” [2] handbook that has been developed by the MSA in collaboration with the Lawrence Hall of Science [3] as part of their Great Explorations in Math and Science (GEMS) series.
Teaching Microscopy At Iowa State University
Authors: Horner HT , Pepper TM , Mattila JW
Published: July 2020

Three rigorous one-semester, graduate-level courses are offered in light microscopy (LM) and scanning (SEM) and transmission electron microscopy (TEM), primarily for graduate students and staff, and for advanced undergraduate students in the teaching complex of the Bessey Microscopy Facility (BMF). These courses have evolved over the years. They include a variety of techniques and laboratory exercises that prepare a successful student to become an independent researcher in the BMF or elsewhere, and to work with any major professor who may not have expertise in microscopy.

Each course consists of: five credits at the 600 level; a limit of 10 students; 11 hours of formal lecture-lab time per week; and additional arranged time for continuation of laboratory procedures and individual operation of microscopes and ancillary equipment. Each student has access to the teaching complex 24 hours a day, seven days a week.
Monitoring SEM Performance
Authors: Chapman Stephen K
Published: July 2020

I was trained as a transmission electron microscope engineer in the mid 1960s. I took resolution tests at least once each year and calibrated all of the microscopes that I attended, it was considered a standard procedure for those maintaining an instrument. Moving into the scanning electron microscope field in the mid 1970s it was natural to carry this practice over to that instrument, but in those days this was considered to be extreme. Now, as a consultant in electron microscopy, I routinely carry out SEM resolution, magnification calibration and contamination rate tests on the instruments that I use. I train operators in the role of preventative maintenance and encourage them to know as much as possible about their instruments as this increases their ability to fault find and maintain their own instruments.

Resolution - in many laboratories most tungsten hairpin instruments are set up for extended filament life rater than for high resolution.
Data Storage on CD-R and CD-RW - Future and Achieving
Authors: Cheng Ping-chin , Chen Ming-Yish
Published: July 2020

Low cost and reliability, optical storage media, in particular the CD-R, has become the main steam data storage media. This presentation is intended to discuss issues related to the CD-rewriteable technology and the longevity of the data stored.

The working principle of CDs can be subdivided into three major categories, the CD-ROM, CD-R and CD-RW. The CD-ROM is primary used for music and software distribution and is manufactured by injection molding process. in contrast, CD-R and CD-RW are storage media allows data storage by users. The manufacture process involves spin-coating a layer of photo-sensitive organic dye on a polycarbonate substrate, then over-coated with a refractive coating. Writing of the data bits was achieved by photo-bleaching processes, which change the absorption properties of the dye. Considering the operation principle, there are many factors influence the reliability and storage life of the CD-R.
Digital imaging: an advanced tool for cryo-TEM studies
Authors: Danino Dganit , Talmon Yeshayahu , Hinshaw Jenny
Published: July 2020

Direct-imaging cryo-electron microscopy combined with CCD cameras provide a powerful tool for studying macromolecular assemblies in the 2 to 300 nm range, which form in biological systems, biomedical solutions, surfactants, microemulsions and a host of other diverse systems. The CCD cameras are especially advantageous for identifying rare assemblies, studying specific assembly details (figures A and B) and transient structures forming during dynamic processes and phase transformations (figures C-E). This setup is also beneficial for exploring coexistence of structures and studying highly radiation-sensitive systems such as oil-continuous solutions. Information on internal ordering is also readily obtained (figure A).

Continuous CCD application at low dose conditions provides numerous significant advantages over classical imaging on photographic plates. First, it allows a preview of the exact area to be recorded (search and focus modes), concentration on specific interesting features and adjustment of microscope parameters for optimal imaging (focus mode), at very low exposures and with minimal radiation damage.