bluuebunny/crossref_metadata_2025_split huggingface dataset:
X-ray detection performance of a 300KV field-emission Analytical Electron Microscope
Authors: Lyman C. E. , Goldstein J. I. , Williams D.B. , Ackland D.W. , von Harrach S. , Nicholls A. W. , Statham P.J. 
Published: June 2020

A major goal of analytical electron micrsocopy (AEM) is to detect small amounts of an element in a given matrix at high spatial resolution. While there is a tradeoff between low detection limit and high spatial resolution, a field emission electron gun allows detection of small amounts of an element at sub-lOnm spatial resolution. The minimum mass fraction of one element measured in another is proportional to [(P/B)·P]-1/2 where the peak-to-background ratio P/B and the peak intensity P both must be high to detect the smallest amount of an element. Thus, the x-ray detection performance of an analytical electron microscope may be characterized in terms of standardized measurements of peak-to-background, x-ray intensity, the level of spurious x-rays (hole count), and x-ray detector performance in terms of energy resolution and peak shape.This paper provides measurements of these parameters from Lehigh’s VG Microscopes HB-603 field emission AEM. This AEM was designed to provide the best x-ray detection possible.
From light to electron microscopic analysis of neurons intracellularly injected in fixed slices with “miniruby”, a fluorescent biocyttn compound
Authors: Liu Wei-lin , Shipley Michael T. 
Published: June 2020

Intracellular labeling of neurons in fixed slices is a very useful method for studying morphological structures of neurons both at light and electron microscopic levels. Recently, biocytin has been widely used for intracellular labeling in living slices because this molecule is highly soluble, has high electrophoretic mobility and has high affinity for avidin. However, biocytin cannot be used in fixed slices because in fixed slices membrane potential cannot be used to signify that a cell is impaled. Thus, in fixed slices it is necessary to inject cells with a fluorescent compound so that impalement and filling can be visualized under fluorescent microscope. We have developed a fluorescent biocytin compound, “Miniruby” (MR), dextran-tetramethylrhodamine-biocytin. previously, we showed that mis molecule provides excellent intracellular labels in fixed slices at the light microscopic level. Here, we demonstrate MR can also be visualized at the electron microscopic level.Fixed slices (200-400 ¼m) of adult rat olfactory bulb, piriform cortex and periaqeductal gray were used.
Comparative studies of Alaria and Diplostomum metacercariae using SEM
Authors: Ujiie M. , Heckmann R. A. , Gardner J. S. 
Published: June 2020

Two species of metacercariae belonging to the genera Alaria and Diplostomum were obtained from lizards in Mexico and fish in Peru. Alaria was found in the lungs of Scleroporus grammicus (Mesquito lizard) and Diplostomum was in the intestines of Orestias agasii (Carachi). To study the taxonomy and morphology of these two parasites, their integuments were compared using SEM.The parasites were fixed in 10% formalin, transferred into 2.5% glutaraldehyde and kept in 70% ethanol to be sent to Brigham Young University. Specimens were dehydrated to 100% ETOH and critical point dried. Samples were mounted on stubs using double-stick tape and were coated with approximately 30 nm of gold. The two species were compared using SEM.The integuments of the two species of metacercariae exhibited major differences. In order to achieve maximum absorption, modification of the surface area of primitive parasites is more extensive than in subsequent species. Alaria was uniformly covered with microvilli - characteristic seen in many of the trematodes ‐ ‐ including its anterior sucker region (Fig. 1, 3).
Lysine effect on ruthenium red and alcian blue preservation of the staphylococci glycocalyx
Authors: Fassel Theresa A. , Sanger James R. , Edmiston Charles E. 
Published: June 2020

The gram-positive coagulase-negative staphylococci are opportunistic organisms important in latent infection associated with prosthetic biomaterials. Their highly charged polysaccharide glycocalyx, or slime, aids in proliferation of bacteria on surfaces after an initial adhesion event, possibly at the time of surgical insertion. The cationic reagents, ruthenium red (RR) and alcian blue (AB), in en bloc procedures have aided visualization of the polysaccharide glycocalyx material in TEM or SEM applications. Further, enhancement of RR preservation or staining of slime by inclusion of lysine in a prefixation stage has been observed. The effect of lysine with and without RR and AB on preservation/staining of the staphylococci glycocalyx is investigated further in this study.Staphylococcus aureus ATCC 25923, Staphylococcus epidermidis RP62 (RP62) and Staphylococcus hominis SP2 (SP2) were cultured in trypticase soy broth for 18 hrs at 35°C, following recovery from frozen storage and plating on blood agar plates for 24 hrs. Cells with 75mM lysine in the prefixation were incubated for 20 minutes with 2.5% glutaraldehyde (GA), 2.5% GA and 0.075% RR, or 2.5% GA and 0.075% AB, respectively.
Microscopy ofTaxomyces andreanae, a new taxon isolated fromTaxus
Authors: Strobel Gary A. , Standing M. D. , Hess W. M. 
Published: June 2020

A newly described fungus,Taxomyces andreanaeStrobel, Stierle, & Hess. has also been isolated from (Taxus brevifoliaNutt.), The growth pattern of the fungus was determined by growing it on various plant species, plant parts and agar cultures. The morphological characteristics appeared to be more diverse when the fungus was grown on twigs of yew wood. Therefore, the purpose of these investigations was to use electron microscopy to more carefully observe the nature of fungal growth and bulbil formation ofT.andreanaeon twigs of yew wood.Small pieces of sterile plant tissues were used to grow the fungus. For microscopy studies, procedures outlined by Upadhyay et al. were used, which consisted of fixation and dehydration followed by critical point drying and sputter coating for SEM, and embedment in Spurr resin for TEM. All SEM photos were taken at 10 kV. Fungal colonies had sparse to very dense concentrations of hyphal cells (Fig. 1) which, in some areas of cultures, produced hyphal cells which averaged from 1.25 μm to larger cells which averaged 3.75 μm in diameter.
Histochemical and immunocytochemical ultrastructural localization of melanocyte specific proteins
Authors: Boissy Ying L. , Orlow Seth J. , Boissy Raymond E. 
Published: June 2020

Melanin synthesis in melanocytes is localized to melanosomes, where enzymatic and structural gene products must be targeted. Some gene products are translocated through different pathways (i.e., tyrosinase travels through the Golgi apparatus during processing, whereas a putative matrix glycoprotein does not). To visualize trafficking routes, we used post-embedding immunocytochemistry to compliment DOPA-histochemistry. We report on the localization of tyrosinase, matrix glycoprotein, tyrosinase-related protein 1 (TRP-1) and lysosome-associated membrane protein-1 (LAMP-1).DOPA histochemistry: Cultured melanoma cells were fixed in half-strength Karnovsky’s, incubated in 0.1 % 1-DOPA 2X for 2.5 h and embedded in Eponate 12. For immunocytochemistry, cells were fixed with 4% paraformaldehyde, 1% glutaraldehyde, and 0.2% picric acid with 0.5 mM CaCl2(pH 7.4) for 20 m at RT, quenched in 50 mM NH4Cl for 20 m at 0°C, washed in 0.1 M maleate buffer (pH 6.5), and treated with 2% uranyl acetate (pH 4.0) for 30 m at 0°C.
An SEM evaluation of normal, hypermineralized, and demineralized human dentin and its interaction with dentin bonding systems
Authors: Perdigao Jorge 
Published: June 2020

The mechanism of bonding to enamel has been described as tag-like resin extensions into the etched enamel structure. However, the mechanism by which resins bond to dentin has not been fully elucidated. Bonding to dentin represents a greater challenge than bonding to enamel due to the organic composition of dentin, the presence of fluid-filled tubules, variations in intrinsic composition, and the presence of the odontoblastic process in dentinal tubules. Bonding to mineralized dentin surfaces is more difficult than bonding to normal dentin. The purpose of this study was to evaluate the morphology of three different dentin substrates and their interaction with four different dentin bonding systems (DBS).One-hundred twenty caries-free human molar teeth stored in an thymol solution were randomly assigned into three groups (n = 40), according to the type of surface treatment. After removing the occlusal dentin, forty teeth were suspended in 600 ml of a mineralizing solution for two weeks.
Low-voltage SEM of urinary stones
Authors: Rez Peter , Reilly Michail 
Published: June 2020

Urinary stones are predominantly composed of calcium oxalate and calcium apatite while a minority of stones are formed from uric acid. The oxalate stones occur with greatest frequency, mainly in the form of the monohydrate (whellewite) with some dihydrate (wedellite) present. Despite many years of extensive research, the mechanisms for kidney stone nucleation and growth are still unknown. In particular the urine from recurrent stone formers, and the urine from those who do not form stones, does not show large differences in concentration of either calcium or oxalate ions. Recent work has emphasised the role of possible “inhibitors” or “promoters” in the growth of urinary stones though the quest for these substances remains elusive. Much effort has been devoted to the study of crystallization of calcium oxalates in an attempt to understand nucleation, aggregation and growth as a function of pH and the presence of possible promoters or inhibitors.Many analytical techniques have been applied to urinary stone analysis with X-ray diffraction, wet chemistry and infrared spectroscopy being the most successful for routine characterisation.
Ultrastructural diagnosis of cryptosporidium in a patient with acquired immunodeficiency syndrome (AIDS)
Authors: Ramirez E. , Ceseñas B. L. A. , Segovia F. 
Published: June 2020

Cryptosporidium sp is an intestinal protozoan that is well known as parasite of different animals,but recently it has been recognized as a cause of human disease, princippally since apparition of the acquired immunodeficiency syndrome (AIDS). In this kind of patients it produces severe diarrhea (loss of a stool volume up to 17 liters per day), this condition may be a major factor leading to death.Information about Cryptosporidiosis and AIDS incidence in developing countries is limited. In this paper we report the ultrastructural study of an intestinal biopsy from an hemophilic man,infected wit HIV through a blood transfussion that presented severe diarrhea.Jejunal biopsy specimen was obtained and prepared for electron microscope study. The specimen was fixed in 2.5% glutaraldehyde in 0.2 M phosphate buffer pH 7.2;postfixed in 1% osmium tetroxide in 0.2M phosphate buffer pH 7.2;dehydrated in ethanol and embedded in epoxy resin (Medcast). Thin sections obtained in a LKB ultratome V with a diamond knife, stained with uranyl acetate and lead citrate, were observed in a Zeiss EM109 electron microscope.
A method for direct measurement of specimen noise in HREM images
Authors: Paciornik Sidnei , Kilaas Roar , Dahmen Ulrich , O'Keefe Michael Adrian 
Published: June 2020

High resolution electron microscopy (HREM) is a primary tool for studying the atomic structure of defects in crystals. However, the quantitative analysis of defect structures is often seriously limited by specimen noise due to contamination or oxide layers on the surfaces of a thin foil.For simple monatomic structures such as fcc or bcc metals observed in directions where the crystal projects into well-separated atomic columns, HREM image interpretation is relatively simple: under weak phase object, Scherzer imaging conditions, each atomic column is imaged as a black dot. Variations in intensity and position of individual image dots can be due to variations in composition or location of atomic columns. Unfortunately, both types of variation may also arise from random noise superimposed on the periodic image due to an amorphous oxide or contamination film on the surfaces of the thin foil. For example, image simulations have shown that a layer of amorphous oxide (random noise) on the surfaces of a thin foil of perfect crystalline Si can lead to significant shifts in image intensities and centroid positions for individual atomic columns.
Imaging biological samples with the atomic-force microscope
Authors: Henderson Eric , Jondle Daniel , Marsh Thomas , Shaiu Wen-Ling , Niu Luming , Vesenka James , Stanley Elis , Haydon Philip 
Published: June 2020

The application of atomic force microscopy (AFM) to biological investigation is attractive for a number of reasons. Foremost among these is the ability of the AFM to image samples, even living cells, under near native conditions and at resolution equal to, or exceeding, that possible by the best light microscopes. Moreover, the ability of the AFM to manipulate samples it images provides a novel and far reaching application of this technology.We have been studying a number of biological samples by AFM. These include conventional and non-conventional nucleic acid structures, ribosomes, neural cells and synapses, cellular organelles (chloroplasts and nuclei), among others. Each of these projects has its own set of associated difficulties and each reveals information about the uses and limits of the AFM in biology. Fig. 1 shows AFM images of various biological samples. In the case of nucleic acids, which have been extensively studied in a number of labs by AFM the problems of signal/noise sample deposition have been overcome in air and organic solvents.
Non-contact atomic-force microscopy for soft surfaces
Authors: Howland R. S. , Oot D. F. , Nowroozi-Esfahani R. , Maclay G. J. , Hesketh P. J. 
Published: June 2020

The atomic force microscope (AFM) was invented in the mid-1980s, in response to strong interest in the high resolution, real-space surface imaging capabilities of the scanning tunneling microscope (STM). The AFM provides one real benefit that the STM cannot: it is able to image insulating surfaces. As a result, the AFM can operate on a wider variety of samples; it also can image samples in air, where many conductors oxidize rapidly, and in solution. Essentially no surface preparation is necessary. Historically, however, even the AFM has had limitations. Until recently, the contact forces exerted by the AFM tip on the sample surface meant that AFM was limited to surfaces of substantial rigidity. Noncontact AFM removes that barrier, opening up the possibility of AFM imaging of very soft surfaces, or of surfaces that cannot be contaminated by contact with the tip.An AFM uses a piezoelectric transducer to scan the sample beneath a sharp probe.
The effect of probe-tip geometry on force microscopy images
Authors: Thornton J. T. , Velu E. M. T. , Mooney C. B. , Russell P. E. 
Published: June 2020

The atomic force microscope (AFM) has been used to characterize a variety of surfaces to study the influence of the instrumental parameters and sample topography on the interpretation of the images and the data obtained. The effect of the tip shape on the resulting image resolution and artifacts has been studied. Test samples of varied topography have been used to establish imaging parameter optimization for specific sample topographies.Chromium thin films of different thickness, deposited uniformly by rf diode sputtering, have been selected as test samples and imaged with a variety of tip shapes. These films were developed as underlayer films for magnetic recording media used in computer hard disks. The range of tips include commercial silicon nitride pyramidal tips, focused ion beam (FIB) sharpened silicon nitride pyramidal tips, and electron beam contamination induced tips (microtips) varying in growth time (i.e. length) from 10 to 40 seconds (approximately 0.40 to 0.65 μm).
Analysis of cryo-electron micrographs of HbS fibers
Authors: Lewis Michael R. , Gross Leon J. , Josephs Robert 
Published: June 2020

We are studying the structure of deoxy-sickle hemoglobin (HbS) fibers by cryo-electron microscopy (cryo-EM). Cryo-EM affords potentially higher resolution than negative staining in part because the electron scattering by unstained protein includes internal structure which may be poorly depicted by an envelope of negative stain. This advantage, however, is partially compromised by a low signal to noise ratio (snr) and low image contrast. Our cryo-EM images were recorded with specimen doses of 7 e-/Å2 at 100 keV, ca. 100 nm defocus, and 39,000 magnification on Kodak SO-163 film.Helical particles usually have a constant pitch. Thus the rotation about the axis is coupled to translation along the length of the particle. HbS fibers, however, have a variable pitch which ranges from 6° to 12° rotation per unit cell length (63 Å). Consequently, the rotation of HbS fibers is partially decoupled from translation and the twist of each unit cell and its relative angular rotation about fiber the axis cannot be determined by particle symmetry.
Compositional mapping of biological material with the scanning ion microprobe
Authors: Levi-Setti Riccardo , Chabala Jan M. , Smolik Sarah 
Published: June 2020

The use of ion probes for microscopy and imaging microanalysis by secondary ion mass spectrometry (SIMS) is a destructive observational technique that can provide information inaccessible to the electron microscope. The damage to the sample caused by the ion-induced sputter erosion of its surface layers is exploited to identify and map the chemical and isotopic composition of the removed layers. Particularly good image resolution (20-70 nm) can be attained with heavy-ion focused probes, as with the University of Chicago 40 keV Ga+ Scanning Ion Microprobe (UC SIM). The application of this instrument to biological research involving mineralized and soft tissue has been evaluated on several occasions, together with the requirements of specimen preparation for SIMS analysis. In a review recently presented, studies of mineralized tissues (bone, teeth) were discussed. We concentrate here on recent directions of our SIMS studies of soft biological material.The sensitivity of SIMS to isotopes of any mass paves the way for the profitable use of tagged, tracer molecules in a host of biological applications as a preferable alternative to the use of radioisotopes and autoradiography.
Direct phase determination from EM images
Authors: Hovmöller Sven , Zou Xiaodong , Eriksson Lars , Svensson Gunnar 
Published: June 2020

EM images contain phase information, in contrast to X-ray and electron diffraction patterns. The phases are extracted from the Fourier transform (FT) of the EM image. However, there has been doubts as to what exactly this phase information is. Are the EM phases the same as those of the crystallographic structure factors F(hkl) as defined in x ray crystallography? Or are the phases so distorted by dynamical scattering that very sophisticated procedures are needed for phase retrieval, as has been suggested.We have investigated this question, by comparing phases obtained from EM-images with those of the x ray structure factors from two accurately refined barium niobium oxide crystals.EM images of Ba4Nb14O23 (orthorhombic Cmmm, a=20.782, b=12.448, c=4.148 Å) and Ba3Nb16O23 (orthorhombic Cmmm, a=20.930, b=12.478, c=4.162 Å) were taken with a Philips CM 30 300kV and a JEOL 200CX 200kV electron microscope. Thin areas near the edge were analyzed by our newly developed image processing system, CRISP.
The atomic-force microscope and its future in biology
Authors: Revel Jean-Paul 
Published: June 2020

The last few years have been marked by a series of remarkable developments in microscopy. Perhaps the most amazing of these is the growth of microscopies which use devices where the place of the lens has been taken by probes, which record information about the sample and display it in a spatial from the point of view of the context. From the point of view of the biologist one of the most promising of these microscopies without lenses is the scanned force microscope, aka atomic force microscope.This instrument was invented by Binnig, Quate and Gerber and is a close relative of the scanning tunneling microscope. Today's AFMs consist of a cantilever which bears a sharp point at its end. Often this is a silicon nitride pyramid, but there are many variations, the object of which is to make the tip sharper. A laser beam is directed at the back of the cantilever and is reflected into a split, or quadrant photodiode.
Structural study of deactivation of gallosilicate catalysts
Authors: Choi-Feng C. , Hall J. B. , Huggins B. J. , Li D. , Kaduk J. A. , Green L. M. , Alexander B. D. , Reagan W. J. 
Published: June 2020

Gallosilicate molecular sieves with an MFI structure are very promising catalysts for upgrading light olefins and paraffins to aromatics. Gallosilicate catalysts are quite stable at low reaction temperature, however, when subjected to high temperature, gallosilicate catalysts deactivate rapidly. The activity and selectivity of these catalysts are greatly influenced by both framework and non-framework gallium. Although the framework gallium imparts acidity to the sieve, the nature of the non-framework gallium is unclear. In the present study, combined techniques of analytical electron microscopy (AEM), high resolution transmission electron microscopy (HREM) and X-ray diffraction (XRD) have been applied to study the fate of framework and non-framework gallium in progressively deactivated gallosilicate molecular sieve catalysts. To study this progressive process, fresh gallosilicate molecular sieve and the gallosilicate catalysts (with 40% Cab-O-Sil matrix) subjected to steaming treatments at different temperatures and durations were characterized.The microstructure of fresh gallosilicate catalysts consists of highly crystalline molecular sieve which is uniformly distributed in the amorphous supporting matrix (Fig. 1).
Characterization of colloidal materials by cryo-TEM
Authors: Minter J. R. 
Published: June 2020

Many researchers develop products and processes that depend upon colloidal materials. Rheological and other important material parameters are influenced by the morphology of the colloid. The photography industry uses many such colloids including silver halide sols, photographic coupler sols and emulsions surfactants, and gelatin solutions and gels. High-resolution direct electron images of these systems in their native states permit photographic scientists to understand how changes in formulation produce changes in microstructure and, ultimately, to understand the photographic performance of the system.We prepare thin biconcave liquid films spanning the holes in a perforated carbon film supported by an electron microscope grid (see Fig 1). To prevent changes in composition of the colloid caused by evaporation, the films are prepared in an environmental chamber and are propelled through a trap door into a container of liquid ethane. The specimen is cooled at a rate sufficient to prevent crystallization of water. When maintained below -150 °C, these specimens are stable and compatible with the high vacuuary of the electron microscope.