bluuebunny/crossref_metadata_2025 huggingface dataset:
Precipitation of NiHfsi phase in NiAl single crystals containing Hf
Authors: Garg A. , Noebe R. D. , Darolia R.
Published: June 2020

Small additions of Hf to NiAl produce a significant increase in the high-temperature strength of single crystals. Hf has a very limited solubility in NiAl and in the presence of Si, results in a high density of G-phase (Ni16Hf6Si7) cuboidal precipitates and some G-platelets in a NiAl matrix. These precipitates have a F.C.C structure and nucleate on {100}NiAl planes with almost perfect coherency and a cube-on-cube orientation-relationship (O.R.). However, G-phase is metastable and after prolonged aging at high temperature dissolves at the expense of a more stable Heusler (β'-Ni2AlHf) phase. In addition to these two phases, a third phase was shown to be present in a NiAl-0.3at. % Hf alloy, but was not previously identified (Fig. 4 of ref. 2 ). In this work, we report the morphology, crystal-structure, O.R., and stability of this unknown phase, which were determined using conventional and analytical transmission electron microscopy (TEM).

Single crystals of NiAl containing 0.5at. % Hf were grown by a Bridgman technique. Chemical analysis indicated that these crystals also contained Si, which was not an intentional alloying addition but was picked up from the shell mold during directional solidification.
EELS characterization of “Smut” layer films on steel surface prepared for chrome plating by anodic etching
Authors: Wang E Y. , Cherian J. T. , Madsen A. , Fisher R. M.
Published: June 2020

Many steel parts are electro-plated with chromium to protect them against corrosion and to improve their wear-resistance. Good adhesion of the chrome plate to the steel surface, which is essential for long term durability of the part, is extremely dependent on surface preparation prior to plating. Recently, McDonnell Douglas developed a new pre-treatment method for chrome plating in which the steel is anodically etched in a sulfuric acid and hydrofluoric acid solution. On carbon steel surfaces, this anodic pre-treatment produces a dark, loosely adhering material that is commonly called the “smut” layer. On stainless steels and nickel alloys, the surface is only darkened by the anodic pre-treatment and little residue is produced. Anodic pre-treatment prior to hard chrome plating results in much better adherence to both carbon and alloy steels.

We have characterized the anodic pre-treated steel surface and the resulting “smut” layer using various techniques including electron spectroscopy for chemical analysis (ESCA) on bulk samples and transmission electron microscopy (TEM) and electron energy-loss spectroscopy (EELS) on stripped films.
TEM examination of wear debris from a self-lubricating metal-matrix composite prepared by ultramicrotomy
Authors: Prasad S. V. , Walck S. D. , Lloyd P. F.
Published: June 2020

Self-lubricating materials are usually multi-phase composites comprising of a solid lubricant dispersed in a matrix of a metal or a polymer. During sliding contact, chemical reactions among the constituent phases of the composite, the counterface and the gases in the surrounding environment are inevitable. The wear debris is a product of such chemical (or tribochemical) reactions. Determination of the chemistry and the crystal structure of the wear debris is therefore crucial to the understanding of the wear mechanisms. In self-lubricating composites, the quantity of the debris generated is often too small to perform x-ray diffraction.

It has been previously demonstrated that self-lubricating aluminum metal-matrix composites can be synthesized by dispersing silicon carbide and tungsten disulfide particles in commercial aluminum alloy matrices. A typical microstructure of an Al-0.10SiC-0.05WS2 MMC is shown in Fig. 1. The friction and wear test was performed, in a ball-on-disk configuration, on a polished disk of the aluminum MMC against a 440C steel ball.
The measurement of the period and strain of semiconductor superlattice systems using HREM
Authors: Robertson M.D. , Corbett J.M. , Currie J.E. , Webb J.B.
Published: June 2020

The quantification of local strains in semiconductor epilayer systems is of technological importance since strain can affect the physical, electrical and optical properties of the material. For the measurement of strains in epitaxial structures on the nanometer scale, high resolution electron microscopy (HREM) images recorded using slow scan charged-coupled device cameras and analyzed using Fourier filtering techniques can provide reliable, quantitative results that are independent of image contrast.

Fig. 1a is a HREM image of about 3 periods from a 20 period In.82Al.18Sb / InSb coherently strained superlattice in [110] zone axis projection. The superlattice was grown by magnetron sputter epitaxy and the growth direction is along [001]. The image was recorded at 200 kV using a Philips CM20 TEM. Displayed is a 128×697 pixel subset of the original 256×1024 image. This image was Fourier transformed to obtain the digital diffractogram and all reflections apart from the [002] were filtered out using elliptical masks of approximately the first Brillouin zone in size. The inverse Fourier transform, displaying the [002] lattice fringes, is presented in Fig. 1b.
Determination of the Si(111)-(√3x√3) Au surface structure using UHV TEM
Authors: Plass R. , Marks L. D.
Published: June 2020

For the past few decades the Si(111)-(√3×√3) Au surface (denoted hereafter as √3-Au) has received considerable attention in the literature as one of the prototypical Si(111)-(√3×√3) Metal systems. The √3 -Au system appears for gold coverages from roughly 0.5 ML to 1.0 ML after annealing of the substrate over 280°C. Several authors have noted the small surface domains of this structure and several possible diffraction spot features associated with different coverages and annealing temperatures. The two dominant models which have been proposed for this surface are the missing top layer twisted trimer (MTLTT) and the conjugate honeycomb chained trimer (CHCT) models.

The √3-Au surface was prepared on bulk Si(111) TEM samples thinned by mechanical polishing and HNO3/HF solution chemical etching. Under UHV conditions the samples were cleaned by cycles of Ar+ ion milling and electron beam annealing until well defined Si(111)-(7×7) diffraction patterns were visible. On these surfaces roughly 0.7 ML of gold was evaporated followed by light electron beam annealing to produce the √3-Au surface. Through exposure electron diffraction patterns from three different sample locations and crystal tilts were collected and the negatives quantified using a cross correlation analysis technique.
Development of electron holography system in field emission electron microscrope
Authors: Takeguchi M. , Tomita T. , Honda T. , Kersker M.
Published: June 2020

Electron holography is a powerful and practical method to know the phase of electron wave quantitatively and enables us to obtain various kinds of physical information such as magnetic and electric field distribution inside/outside of the specimen, thickness of the crystal etc. Since this method requires an FE-TEM equipped with an electron biprism and some electron hologram reconstruction methodology, the general EM users is typically not yet familiar with electron holography practice. The recent introduction of commercial type FE-TEM, however, brings some users the opportunities of practical electron holography applications. We have recently developed an electron holography system for our FE-TEMs, the JEM-2010F and the JEM-3000F. The components, specifications and some application data are presented below:

Our electron holography system consists of electron biprism, power supply and hologram reconstruction processor(PC + software). The electron biprism is rotatable and the beam-splitting electrode(a Pt wire of 0.6 μm in diameter) can be cleaned by direct heating. The electron biprism is of the cartridge type for easy maintenance, thus removing the necessity of wire exchange.
The performance of analytical EMS and EDX systems, measured with a nickel oxide test specimen
Authors: Wong Kaikee , Egerton R.F.
Published: June 2020

A test specimen consisting of a 50nm film of NiO on a 200-mesh molybdenum grid can be used to evaluate the diffraction, EELS and EDX capabilities of an analytical TEM. Several laboratories have utilised this specimen and their results have been compared. One measurement is the Mo-Kα/Ni-Kα ratio, which characterizes the amount of stray radiation within a TEM column; values are typically in the range 3 to 10 for conventional TEM's and as high as 40 for instruments in which beryllium sheet is used to shield the upper and lower polepieces; see Fig. 1. Another criterion is the peak/background ratio of the Ni-Kα peak, the background being measured within a lOeV window beneath the peak. This ratio reflects electronic noise as well as column radiation but correlates well with the Ni-Kα/Mo-Kα ratio (see Fig. 1), indicating that column radiation can substantially affect the EDX background.

The variations in performance visible in Fig. 1 are partly due to differences in TEM accelerating voltage. Fig. 2 shows that higher peak/background is possible at higher voltage, as would expected if the background were entirely bremsstrahlung radiation.
The detection of Xe gas bubbles in MgO high-resolution lattice images
Authors: McKernan Stuart , Grant Norton M.
Published: June 2020

Room temperature implantation of noble gases into metal and ceramic targets results in the formation of gas bubbles within the crystalline matrix. The pressure within these bubbles is sufficient to stabilize the gas in a crystalline form which, in general has an epitactic relation with the matrix. The size of the bubbles increases with increasing noble gas fluence. As the size of the bubbles increases, the pressure within the bubble decreases. There is therefore a limiting size for the bubble above which the trapped noble gas exists in the fluid phase rather than as a crystalline inclusion. Because of the large size of the noble gas atoms they do not diffuse through the material at an appreciable rate after the implantation event, and thus probably rely on the presence of structural defects in the matrix to coalesce into bubbles. The ability to detect and measure small bubbles in a crystalline matrix is therefore an important step in characterizing the implanted material and understanding the formation mechanism of the bubbles.
Digital differential hysteresis iimage processing displays what the microscope acquires but the eye can't see
Authors: Peters Klaus-Ruediger
Published: June 2020

Differential hysteresis processing is a new image processing technology that provides a tool for the display of image data information at any level of differential contrast resolution. This includes the maximum contrast resolution of the acquisition system which may be 1,000-times higher than that of the visual system (16 bit versus 6 bit). All microscopes acquire high precision contrasts at a level of <0.01-25% of the acquisition range in 16-bit - 8-bit data, but these contrasts are mostly invisible or only partially visible even in conventionally enhanced images. The processing principle of the differential hysteresis tool is based on hysteresis properties of intensity variations within an image.

Differential hysteresis image processing moves a cursor of selected intensity range (hysteresis range) along lines through the image data reading each successive pixel intensity. The midpoint of the cursor provides the output data. If the intensity value of the following pixel falls outside of the actual cursor endpoint values, then the cursor follows the data either with its top or with its bottom, but if the pixels' intensity value falls within the cursor range, then the cursor maintains its intensity value.
Experimental study on the measurement of TEM parameters with the phase spectrum
Authors: Ichise Norihiko , Watanabe Syunya , Ogasawara Mitsuo , Baba Norio
Published: June 2020

For HRTEM works, it seems to be indispensable to measure and control TEM parameters : defocus, astigmatism and beam tilt misalignment. The autotuning method with phase spectra was proposed by Koster, which has theoretical advantages to the previous methods as described in his paper (e.g., the method is specimen independent). However, it seems that experimental study using the phase spectrum itself is insufficient. In our study, it was found that to make the method practical use some additional modifications are necessary.

One among modifications was the correction of the image drift during recording tilted images. The image drift is a serious problem for the method because it is based on measuring the beam tilt induced image displacement. The phase spectrum is so sensitive as not to neglect one pixel drift. The image drift also disturbs recoding images in on-line.
Structural and chemical analysis by transmission and scanning Electron Microscopy of particles found in eyes of cataract patients
Authors: Barron D.
Published: June 2020

There has been a problem associated with removal of cataracts noted by a number of ophthalmologists, in particular, from Dr. David George at the Madigan Army Medical Center in the state of Washington. Particles were found lodged in the eyes of patients after the cataract operation (see fig. 1). There was serious concern about the origin of the particles. Were they from the ultrasonic surgical head, the surgical blade, or were they from a long time accumulation of the metals found in the body? In an effort to find answers, Dr. George sent samples of the cataract tissue filtered through a Whatman filter to the U.S. Army Center for Health Promotion and Preventive Medicine (CHPPM) for analysis by transmission electron microscopy (TEM), scanning electron microscopy (STEM), x-ray elemental spectral analysis (EDAX), and selected area electron diffraction (SAED). The results were compared with the composition of sample particles from the ultrasonic head and the surgical blade. These particles were filed off the head and blade and secured to a formvar film stretched over a TEM grid. Each set of particles was then analyzed by TEM and a x-ray elemental spectrum was generated.
Mapping viscoelasticity, (specific) adhesion and near-field fluorescence of cellular structures with scanning probe microscopy
Authors: de Grooth B.G. , van Hulst N.F. , Greve J. , Berger C.E.H. , Moers M.H.P. , van der Werf K.O.
Published: June 2020

One of the major features of scanning probe microscopy is the ability to produce high-resolution images in air and in liquid. This makes these microscopes potentially very useful for the study of biological materials. Indeed the number of reports that use these microscopes, especially the atomic force microscope (AFM), has increased exponentially in the past decade. However, in order to become a routine apparatus that is able to image live processes at a scale of a few nanometers, the instrumentation of the AFM has to be improved. First of all, under normal operation, the movement of the tip across the surface of fragile biological structures such as cell membranes, often results in movement or even destruction of the object. Secondly, the lack of specificity of the AFM makes it difficult to identify the observed structures. Other problems include the low imaging speed and problems associated with the tip-sample convolution. Here we will report on attempts to improve the first two points: sample destruction and specificity.

It has become clear recently that for operation in air the so-called tapping mode AFM is much more gentle for the sample than the standard operation mode.
Capacitance imaging with a scanning force microscope
Authors: Anderson R. , Siriwardane H. , Fraundorf P. , Stivers T.
Published: June 2020

Scanning force microscopes show topography, but alone cannot provide insight into the electrical properties of either a specimen or particular features of a specimen. In this project we will look at a specimen that consists of conductive spheres in a base of insulating material (FIG. 1a).A theoretical capacitance image corresponding to this particular arrangement of conductive spheres is shown in Figure 1b. Figure 2 is an x-derivative image of Figure 1b, displayed with a logarithmic gray scale to show more of the image structure. The mechanism that generates the raw data image is an electronic “black box” (capacitance differentiator) which produces a voltage proportional to the change in capacitance measured from one point on the specimen to the next We will talk more about the workings of the differentiator below. The voltage from the differentiator, modeled in the derivative image of Figure 2, is recorded to provide a map of the specimen’s electrical properties.
Nuclear localization of initiation factor 2 in neuron primary cultures
Authors: Alonso F.J. Martinez , Lobo M.V. Toledo , Martínez S. Rodriguez , Postigo F.M. Muñoz , Castro J.J. López-Fando
Published: June 2020

The dominant mechanism that controls protein synthesis is the phosphorylation/dephosphorylation of initiation and elongation factors, with a translational control function. Each phase of protein synthesis is promoted by some of these factors that transiently interact with ribosomes, mRNAs and aminoacyltRNAs. Eukaryotic initiation factor-2 (eIF2, 130 kD) is one of these proteins and it is composed of three subunits: alpha, beta and gamma. eIF2 forms a ternary complex (GTP-eIF2-Met tRNAi) that can then interact with the 40S ribosomal subunit which in turn binds mRNA and the 60S ribosomal subunit to form the 80S initiation complex. The relation between eIF2 and the ribosomes is then a well established aspect of protein synthesis, but there are no previous studies about the distribution of eIF2 within the cell.

Using immunocytochemical techniques, we show the distribution of eIF2 within the cell found in primary cultures of rat embryo brain neurons, in which eIF2 and eIF2-kinases have been identified. Primary culture neuron cells were grown in D15 and N2 mediums for 8 days.
What do nanometer molecular trajectories tell us about heterogeneous cell surface domaines?
Authors: Webb Watt W.
Published: June 2020

Plasma membrane heterogeneity is implicit in the existence of specialized cell surface organelles which are necessary for cellular function; coated pits, post and pre-synaptic terminals, microvillae, caveolae, tight junctions, focal contacts and endothelial polarization are examples. The persistence of these discrete molecular aggregates depends on localized restraint of the constituent molecules within specific domaines in the cell surface by strong intermolecular bonds and/or anchorage to extended cytoskeleton. The observed plasticity of many of organelles and the dynamical modulation of domaines induced by cellular signaling evidence evanescent intermolecular interactions even in conspicuous aggregates. There is also strong evidence that universal restraints on the mobility of cell surface proteins persist virtually everywhere in cell surfaces, not only in the discrete organelles. Diffusion of cell surface proteins is slowed by several orders of magnitude relative to corresponding protein diffusion coefficients in isolated lipid membranes as has been determined by various ensemble average methods of measurement such as fluorescence photobleaching recovery(FPR).
Identification of antigenic epitotes on hepatitis E virus by immune Electron Microscopy
Authors: Humphrey C.D. , McCaustland K.A. , Paltel P. , Khudyakov Yu. E. , Fields H.A.
Published: June 2020

Outbreaks of enterically transmitted hepatitis involving many thousands of cases have occurred in southern and central Asia, North Africa, and Latin American countries. Hepatitis E virus (HEV), a major cause of the disease is a 27-32nm virus that has features resembling those of "small round structured viruses" (e.g. Norwalk agent). Usually, for identification by electron microscopy, immune electron microscopy (IEM) is required to trap or aggregate the virus.

Analysis of the HEV genome has identified 3 open reading frames (ORF) within the positive single-stranded RNA 7.5kb molecule. ORF1 appears to code for nonstructural proteins, while ORF2 and ORF3 are considered to code for structural capsid-associated proteins. Recently, the antigenic nature of the ORF2 and 3 coded putative structural proteins was shown in various immunoassays by the application of synthetic peptides and recombinant proteins. In this study, we tested whether antisera (guinea pig) to immunoreactive synthetic peptides encoded by ORF2 and ORF3 would identify HEV by IEM.
Localization of C-FOS and C-JUN proto-oncogene proteins in rat pleural mesothelial cells by immunofluorescence and confocal scanning laser microscopy
Authors: BéruBé K.A. , Taatjes D.J. , Hoag A. , Mossman B.T.
Published: June 2020

The proto-oncogenes c-fos and c-jun are members of a multigene family known as immediate early genes (IEG) that are transiently expressed in response to a wide variety of environmental stimuli. Homodimeric complexes of jun gene-family products and heterodimeric complexes of the jun and fos gene-family products form the transcription factor AP-1, which can bind to the promoter region of genes involved in cell proliferation.

Here we report on the expression and localization of the nuclear proteins c-fos and c-jun in rat pleural mesothelial (RPM) cells. Previous work in our lab has shown that in RPM cells crocidolite asbestos is a potent and persistent inducer of c-fos and c-jun mRNA and AP-1 DNA-binding activity. Furthermore, asbestos may act as a mitogen in carcinogenesis by persistently activating the early response gene pathway. Although c-fos and c-jun message levels are increased in RPM cells after exposure to asbestos, it is unclear whether their proteins localize exclusively in proliferating RPM cells.
The protease phenotype and crystalline nature of the granules of intraepithelial mast cells inTrichinella spiralis-infected mice
Authors: Friend D.S. , Ghildyal N. , Gurish M.F. , Austen K.F. , Stevens R.L.
Published: June 2020

Trichinella spiralisinduces a profound mastocytosis and eosinophilia in the small intestine of the infected mouse. Mouse mast cells (MC) store in their granules various combinations of at least five chymotryptic chymases [designated mouse MC protease (mMCP) 1 to 5], two tryptic proteases designated mMCP-6 and mMCP-7 and an exopeptidase, carboxypeptidase A (mMC-CPA). Using antipeptide, protease -specific antibodies to these MC granule proteases, immunohistochemistry was done to determine the distribution, number and protease phenotype of the MCs in the small intestine and spleen 10 to >60 days afterTrichinellainfection of BALB/c and C3H mice. TEM was performed to evaluate the granule morphology of the MCs between intestinal epithelial cells and in the lamina propria (mucosal MCs) and in the submucosa, muscle and serosa of the intestine (submucosal MCs).

As noted in the table below, the number of submucosal MCs remained constant throughout the study. In contrast, on day 14, the number of MCs in the mucosa increased ~25 fold. Increased numbers of MCs were observed between epithelial cells in the mucosal crypts, in the lamina propria and to a lesser extent, between epithelial cells of the intestinal villi.
Field emission SEM and back-scattered electron imaging of microwave silver-stained bacterial lipopolysaccharide on clinical slides of septic patients
Authors: Giammara B. L. , Bone R. C. , Eubanks D. H. , Hanker J. S.
Published: June 2020

Several stains have emanated from the classic work of Hanker et al. which provide highly visable and electron opaque end products. These allow back-scattered electron imaging (BEI) and visualization of polymerized 3, 3'-diaminobenzidine (DAB) or p-phenylenediamine/pyrocatechol (PPD/PC) on endogenous enzyme or nonenzyme hemoproteins, or visualization of exogenous horseradish peroxidase (HRP) transported in tissue or attached to cells, or immunoperoxidase localized to tissue antigen or receptor sites. Additionally, the Giammara-Hanker PATS reaction (Pat.Appl. No. 08/225,058), originally used to show biomacromolecules or structures such as glycogen, basement membranes, reticular fibers or lipopolysaccharide, appears to be a positive stain for Gram (-) bacteria, including spirochetes, as well as for neutrophils and activated macrophages. The PATS reaction also demonstrates sites of calcification in tissues and certain calcium compounds by both light and electron microscopy. Likewise, an improved FETS reaction uses silver as an electron opaque Feulgen-type reaction for DNA and demonstrates DNA in bacteria and Candida albicans as well as other cellular nuclei.
Cryo Electron Microscopy of SSV1 phage particles
Authors: Ziese U. , Typke D. , Hegerl R. , Baumeister W.
Published: June 2020

SSVl phages are lemon-shaped particles, normally about 90 nm x 40 nm in size, with short tail fibres attached to one pole, produced by the thermophilic archaeon Sulfolobus shibate, isolate B12. They are made of 3 different proteins and DNA (15.5 kbp). Two proteins, together with host lipid, form the envelope, the third protein is associated with the DNA. Interestingly, this virus produces particles of varying size and shape. We have investigated the mass of the virions by STEM mass determination, the inner structure by cryo-electron microscopy, and the shape variability by electron tomography. Automatic electron tomography (AET) has been shown to be a useful technique for collecting 3D structural data of individual biological particles under low dose conditions, in negative stain as well as in frozen-hydrated preparations.

Taking electron micrographs of vitrified samples we obtained images revealing some details of the inner structure and, on some particles, a periodic structure of the envelope. (Fig. 1a-b) The inner structure has periodicities of about 2.5 nm, which is in agreement with that found by Lepault et al on vitrified samples of the phages lambda and T4.
Ultrastructural identification of opportunistic organisms in autopsy tissue
Authors: Siew S. , deMendonca-Calaca W. , Penner J.
Published: June 2020

Opportunistic infections pose a progressively greater threat to the immunocompromised patient both as a cause of morbidity and mortality. Difficulty may be experienced with the establishment of a definitive diagnosis of such infections during life. We report the ultrastructural identification in autopsy lung material of Pneumocystis carinii of two immunocompromised patients and Herpes nucleocapsids in a third case. These three patients were young adults, two men and one woman. All of them died of the pulmonary complications of the acquired immunodeficiency syndrome (AIDS). One of the men and the woman had a history of sexual promiscuity. The former was a homosexual, whose lover had predeceased him, six months ago. The other young man was an innocent victim of medical progress. As a hemophiliac, he had been on intravenous therapy with anti-hemophilic globulin.

At autopsy, their lungs were increased in size and weight and they were indurated. The light microscopic findings of the lungs of the first two cases were similar. They varied in the degree of reactive fibrosis.
Ion composition of the contractile vacuole of Acanthamoeba castellanii as determined by x-ray microanalysis
Authors: Bowers B. , Shi S.L. , Sun S.Q. , Leapman R.D.
Published: June 2020

The contractile vacuole (CV) is an osmoregulatory organelle found in free-living protozoa that functions to pump water out of the cell. In amoebae it comprises at least two distinct systems, a spongiome of tubules and/or vesicles that surround a central collecting vacuole (Fig 1). The filling phase and the discharge of the engorged vacuole appear to be independently regulated. Calmodulin, alkaline phosphatase ,and a proton pump are known to be specifically associated with the CV complex in amoebae, but the mechanism of water pumping is not known. In order to gain insight into possible ion transport mechanisms, we have examined the ion content of the CV of the small soil amoeba,Acanthamoeba castellanii, by analytical electron microscopy.

For analytical electron microscopy amoebae were incubated in growth medium with 5% polyvinyl pyrrolidone (PVP), MW 360,000, for 1.5 hours, then concentrated by centrifugation and rapidly frozen by plunging into liquid nitrogen-cooled ethane. The frozen samples were cryosectioned and cryotransferred at -180° C into a VGHB501 STEM equipped with a Gatan parallel energy loss spectrometer (EELS) and a Noran energy dispersive X-ray spectrometer (EDXS).
AFM investigation of endothelial fenestrae
Authors: Wisse E. , Braet F. , Kalle W. , de Grooth B. , Raap A. , Tanke H.
Published: June 2020

Endothelial cells of rat liver sinusoids (LEC) contain fenestrae, which are clustered in sieve plates. These open fenestrae, with an average diameter in the order of 0.1 μm, control the exchange of fluids, solutes and particles between the blood and the parenchymal cells. The surface of LEC can optimally be imaged by scanning electron microscopy (SEM). SEM can also be used to study dynamic changes in fenestrae by comparing specimens subjected to different experimental conditions. However, the SEM uses fixed, dried and coated specimens. Recently, the atomic force microscope (AFM) was introduced, enabling the analysis of cell surfaces under fluid. We used the AFM for the investigation of fenestrae in cultured LEC, whereas SEM served as a reference.

LEC were isolated by collagenase perfusion and purified by a Percoll gradient and selective adherence. After spreading on collagen, LEC were cultured for 8 h. Cells were fixed in 2% glutaraldehyde (12 h), followed by 1% tannic acid (1 h) and postfixed in 1% osmium. Samples were dehydrated in alcohol, critical point dried in ethanol / CO2, and sputter coated with gold, We compared imaging of dried-coated (SEM and AFM), dried-uncoated (AFM) and wet-fixed (AFM) specimens in a series of experiments, with the purpose to prepare for depicting living cells in vitro.
Myofibrillogenesis and myofiber pattern in normal and angiotensin induced cardiac inversion in developing rat heart
Authors: Price RL , Fu L , Simpson DG , Borg TK , Terracio L
Published: June 2020

Myofibrillogenesis, myofiber pattern formation, and heart looping respond to physical, hormonal and teratogenic agents. In cell culture, myofibrillogenesis and myofiber pattern formation depend on coordinated expression of cytoskeletal and myofibrillar components and signals from extracellular matrix (ECM). However, these experiments have been conducted with isolated cardiac myocytes in which phenotype of myocytes is stellate rather than tubular as found in situ.

Whole embryo culture (WEC) allows in situ interactions to occur during controlled application of perturbatory agents. Application of 10 μg/ml angiotensin to WEC results in 10% cardiac inversion (controls - 0% inversions). In this condition, hearts loop right, rather than left as in normal development. We are using confocal scanning laser microscopy (CSLM), transmission electron microscopy (TEM), and image reconstruction techniques to examine myofibrillogenesis and myofiber pattern formation in embryos allowed to develop in utero and WEC.

Rat hearts 9.5 to 11.5 days in utero development, and hearts 9.5 days in utero and 48 H WEC were examined by CSLM and TEM.
Ulrtrastructural analysis of satellite cells in skeletal muscle of obese and lean LA/N-facp rats
Authors: Domaschko D. W. , Edelmann R. E. , Kahle E. B.
Published: June 2020

The biochemical phenomena associated with obesity have been studied extensively. Hollands and Cawthorn have reported that the back postural muscle in the ob/ob obese mouse model are responsible for nearly as much fatty acid production as the liver. The hindlimb musculature has been shown to produce higher levels of fatty acids in venous return blood when compared to the arterial blood. These studies have shown the ability of obese muscle to serve as major sites of fatty acid synthesis in the obese animals. This study has sought to identify any ultrastructural variations in red skeletal muscle from the hindlimb and back postural muscles. These studies have revealed aberrations in the satellite cells between the obese and lean phenotypes as well as the presence of lipid droplets in the capillaries of the obese animals’ psoas major muscle.

Samples were taken from the bellies of the psoas major representing the back postural muscles and the gastrocnemeius and soleus muscles representing the hindlimb muscle.
Ultrastructural observation of human secondary yolk sac
Authors: Beckman D.A. , Wang YP. , Yang G. , Zeng M. , Wang YP. , Xiao KZ. , Holshek J. , Brent R.L.
Published: June 2020

The human secondary yolk sac persists for a short but critical period of development during early organogenesis. Although it is established that the yolk sac is the site of origin of several cell lines, a locus of hematopoiesis and secretes several proteins, the yolk sac may have other as yet less well defined functions. Here we focus on ultrastructural evidence of the role of the human yolk sac as an organ of exchange with the extraembryonic coelom and the yolk-sac cavity. Yolk sacs of 6 to 10 weeks developmental age were fixed and processed for light microscopy, TEM and SEM by standard procedures. Numerous microvilli, coated and uncoated vesicles, and lysosomes in the mesothelial layer together suggest a high capacity for pinocytosis of coelomic fluid and lysosomal digestion of internalized substrate. It is not known whether this process is a significant nutritional source for the yolk sac and embryo as it is in the rodent. Both SEM and TEM observations provide evidence of cilia on dispersed cells in the endodermal layer lining the yolk sac cavity. To our knowledge, there is only one other brief report of cilia on the human yolk sac.
SEM of shell-free cysts of the brine shrimp artemia franciscana (anostraca) in the process of hatching
Authors: Rosowski James R. , Gouthro Mark A. , Belk Denton , Lee Kit W.
Published: June 2020

Air-dried, shell-free cysts of brine shrimp occasionally are used in aquaculture as a food substitute for live nauplii hatched from shelled cysts. Imbibed embryos of shell-free cysts are surrounded by an embryonic cuticle 1 (ECl) composed of an outer and inner cuticular membrane with a fibrous layer in between. Such imbibed embryos, when never air dried but used immediately or dehydrated and stored in a hypertonic salt solution, retain high viability. Although the hatching stages of shelled cysts have been documented with scanning electron microscopy (SEM), no SEM study has examined the hatching of nauplii from cysts without shells, which was the purpose of the present study.

Great Salt Lake shelled cysts (Sanders Brine Shrimp Company, Ogden, Utah, U.S.A.) were treated with a mixture of bleach and sodium hydroxide to dissolve their shells. After washing in tap water, the shellfree cysts were placed in a Petri dish on a filter paper that had been saturated with a salt solution consisting of 28 g NaCl plus 6 g of NaHCO3 / liter, for 15 hr at 28° C in a lighted incubator.
Advances in imaging SIMS studies of stained and BrdU-labelled human metaphase chromosomes
Authors: Levi-Setti R. , Chabala J. M. , Espinosa R. , Le Beau M. M.
Published: June 2020

We have shown previously that isotope-labelled nucleotides in human metaphase chromosomes can be detected and mapped by imaging secondary ion mass spectrometry (SIMS), using the University of Chicago high resolution scanning ion microprobe (UC SIM). These early studies, conducted with BrdU- and 14C-thymidine-labelled chromosomes via detection of the Br and 28CN- (14C14N-> labelcarrying signals, provided some evidence for the condensation of the label into banding patterns along the chromatids (SIMS bands) reminiscent of the well known Q- and G-bands obtained by conventional staining methods for optical microscopy. The potential of this technique has been greatly enhanced by the recent upgrade of the UC SIM, now coupled to a high performance magnetic sector mass spectrometer in lieu of the previous RF quadrupole mass filter. The high transmission of the new spectrometer improves the SIMS analytical sensitivity of the microprobe better than a hundredfold, overcoming most of the previous imaging limitations resulting from low count statistics.
Isoform PMCA3 of the plasma membrane calcium pump (ATPase) is localized in the inner plexiform layer of rat retina
Authors: Antonelli M. C. , Eakin T. J. , Stahl W.L.
Published: June 2020

Regulation of cytosolic Ca2+ is of critical importance for maintaining normal cellular function in the nervous system. Control of calcium homeostasis involves the Ca2+-ATPase of plasma membrane (PMCA) and other transporters. The presence of these regulatory molecules may not be a fixed characteristic of cells in a general sense. Rather, each class of cells may utilize a unique combination of transporters to maintain homeostatic control. In addition, unique distributions of transport molecules and their isoforms may exist in individual parts of cells imparting unique transport signatures to specific cell types. PMCA is a major regulator of calcium transport under normal physiological conditions. In order to understand localization of PMCA isoforms in specific cells we have localized specific PMCA mRNAs by in situ hybridization and translated PMCA protein by immunocytochemistry. The present work is focused on localization of PMCA3, an isoform predominantly known to exist in brain and skeletal muscle, but not previously investigated in retina. We previously showed that mRNA encoding rat plasma membrane Ca2+-ATPase isoform PMCA3 was localized in the granule cell layer of the cerebellum.
Ultrastructural identification of three types of sensory setae on copepod antennae
Authors: Weatherby T. M. , Lenz P.H.
Published: June 2020

Crustaceans, as well as other arthropods, are covered with sensory setae and hairs, including mechanoand chemosensory sensillae with a ciliary origin. Calanoid copepods are small planktonic crustaceans forming a major link in marine food webs. In conjunction with behavioral and physiological studies of the antennae of calanoids, we undertook the ultrastructural characterization of sensory setae on the antennae of Pleuromamma xiphias.

Distal mechanoreceptive setae exhibit exceptional behavioral and physiological performance characteristics: high sensitivity (<10 nm displacements), fast reaction times (<1 msec latency) and phase locking to high frequencies (1-2 kHz). Unusual structural features of the mechanoreceptors are likely to be related to their physiological sensitivity. These features include a large number (up to 3000) of microtubules in each sensory cell dendrite, arising from or anchored to electron dense rods associated with the ciliary basal body microtubule doublets. The microtubules are arranged in a regular array, with bridges between and within rows. These bundles of microtubules extend far into each mechanoreceptive seta and terminate in a staggered fashion along the dendritic membrane, contacting a large membrane surface area and providing a large potential site of mechanotransduction.
Morphologic changes in the anteroventral cochlear nucleus of acoustically-deprived gerbil
Authors: Yu Shang-Ming , Du Shian-Jyue
Published: June 2020

Microcystic lesions are reported as a neurodegenerative disorder in the cochlear nucleus of the Mongolian gerbil. These lesions resemble the spongioform degeneration. Such lesions are large holes, cavities or vacuoles and are also known as the microcysts. The microcysts develop in the neuropil or appear in the neuronal perikarya, degenerated axons and dendrites. The number and size of the microcysts is greatly reduced either by the elevation of auditory thresholds or by the conductive hearing loss induced by ligation of the external auditory canal. Furthermore, absence of the microcysts is found in the old deaf animals. This study was to investigate the morphologic changes in the anteroventral cochlear nucleus (AVCN) of the acoustically-deprived gerbil following the sequence of time courses after ligation of the external auditory canal during postnatal development.

The mongolian gerbil, Meriones unguiculatus, had been acoustically deprived on the right side by a surgical ligation of the external auditory canal at postnatal day 12-14.
Automated cell counting of astrocytes on patterned substrates containing aliphatic and charged properties
Authors: Shain W. , Ancin H. , Craighead H.C. , Isaacson M. , Kam L. , Roysam B. , Szarowski D. , Turner J.N. , Turner S.W.
Published: June 2020

Neural protheses have potential to restore nervous system functions lost by trauma or disease. Nanofabrication extends this approach to implants for stimulating and recording from single or small groups of neurons in the spinal cord and brain; however, tissue compatibility is a major limitation to their practical application. We are using a cell culture method for quantitatively measuring cell attachment to surfaces designed for nanofabricated neural prostheses.

Silicon wafer test surfaces composed of 50-μm bars separated by aliphatic regions were fabricated using methods similar to a procedure described by Kleinfeld et al. Test surfaces contained either a single or double positive charge/residue. Cyanine dyes (diIC18(3)) stained the background and cell membranes (Fig 1); however, identification of individual cells at higher densities was difficult (Fig 2). Nuclear staining with acriflavine allowed discrimination of individual cells and permitted automated counting of nuclei using 3-D data sets from the confocal microscope (Fig 3). For cell attachment assays, LRM5 5 astroglial cells and astrocytes in primary cell culture were plated at increasing cell densities on test substrates, incubated for 24 hr, fixed, stained, mounted on coverslips, and imaged with a 10x objective.
Stereology of liver lesions induced by feeding PCB 153 [2,2’,4,4’,5,5’- hexachlorobiphenyl] to the rat
Authors: Peng J. , Singh A. , Ireland W. , Chu I.
Published: June 2020

Polychlorinated biphenyls (PCBs) are persistent environmental contaminants. A potential health hazard exists for humans and animals because of the PCBs long half-life and capacity to bioaccumulate in the aquatic and terrestrial food chains. The liver is known to be the most significantly affected organ following experimental exposure to PCBs. We have reported the ultrastructure of liver of rats orally administered PCB 153 for 13 weeks. In the present work stereology was applied to estimate measurements of the ultrastructural lesions in the liver.

Twelve Sprague-Dawley rats of both genders were distributed into four groups comprising three animals of each gender. Animals in treated groups received diets containing PCB 153 (dissolved in 4% corn oil) at 50,000 ppb concentration; animals in control groups received diets containing corn oil only. The animals were euthanized 13 weeks after the onset of the experiment. Liver specimens were harvested from the animals, fixed in buffered 2% glutaraldehyde and post-fixed in 2% osmium tetroxide.
Ultrastructure of experimental crush injury in rats
Authors: Coleman Raymond , Mazor Ludmilla , Silbermann Michael , Rubinstein Irit , Better Ori S.
Published: June 2020

Crush Syndrome is a potentially life-threatening condition that develops in humans trapped under debris of collapsed building such as occur in mass catastrophes such as earthquakes, volcanic eruptions and following explosions such as those of bombings or missile attacks. Traumatic pressure damage on limbs can result in myopathy and rhabdomyolysis. The consequences of muscle breakdown lead to major physiological disturbances and may result in acute renal failure if the condition is not recognised and dealt with as an emergency. Whereas there is now considerable progress in treating the condition, much less is known about the basic biology of the muscle pathology and the potential for repair of the traumatized muscle. In the present study we have developed a rat model in which controlled external pressure is used to mimic crush damage in humans, and we have followed the early stages of muscle damage and repair using histological and ultrastructural techniques.
Effects of nuclear polyhedrosis virus formulations on Lymantria dispar larval peritrophic membrane
Authors: Shields K. S. , Podgwaite J. D.
Published: June 2020

The peritrophic membrane is a continuous tube that encases the food in the midgut and hindgut of Lepidopteran larvae. It presumably protects midgut cells from abrasion by food particles, and perhaps acts as a barrier to infection. The gypsy moth, Lymantria dispar, is susceptible to a nuclear polyhedrosis virus (LdMNPV), which is transmitted per os. Once ingested, viral occlusion bodies (OB) dissolve in the alkaline midgut, liberating virions that ultimately invade susceptible cells. Recent studies have shown that selected stilbenedisulfonic acid derivatives administered in combination with LdMNPV significantly enhance viral potency, but the precise mode of action is unknown. We tested the effect of the stilbene derivative, Blankophor BBH (Burlington Chem. Co., Burlington, NC), on potency of LdMNPV in gypsy moth larvae, and determined the effects of ingested BBH/LdMNPV combinations on the surface structure of the peritrophic membrane.

Newly molted second instar larvae were fed high wheat germ diet overlaid with either water, LdMNPV (102-106 OBs/ml), BBH (0.5%), or LdMNPV + BBH.
Human T-lymphocytes (Jurkat cells) expressing HIV-1 TAT-72: SEM
Authors: Koch J. , Gilloteaux J. , Jamison J. M. , Summers J.L.
Published: June 2020

The human immunodeficiency virus (HIV-1) is dependent upon the synthesis of TAT for efficient transcriptional activation and replication. Following translocation to the nucleus TAT interacts with a cis-acting TAT-responsive element located between nucleotides +1 to +42 within the HIV- 1 long terminal repeat. This region contains an RNA stem loop structure TAR, which interacts with TAT and cellular proteins to increase transcription 1000 fold.

We have transfected human T-lymphocytes with an expression vector containing the HIV-1 LTR driving the synthesis of TAT-72. A stable cell line was generated by selection with G418. Cells were grown on round glass coverslips coated with a solution of fibronectin overnight (at 37°C). In addition, cells on coverslips were fixed with a 3.2% glutaraldehyde buffered solution (0.1M Na cacodylate) for 5 min at room temperature, then 15 min at 4°C, then washed gently in a buffer-sucrose solution. Postfixation was performed with an aqueous mixture containing 1.5% OsO4+ 0.5% RuO4 for 20 min at 18°C.
3-D imaging of respirable size asbestos fibers in rat and human lung tissue
Authors: Rogers R.A. , Antonini J.M. , Lai J. , Ekstein B.A. , Oldmixon E.H. , Ducatman B.S. , Brain J.D.
Published: June 2020

Pulmonary exposure to natural and artificial fibers can result in serious health impacts to many segments of the occupational work force in the U.S. and worldwide. The toxicological response of a fiber on the respiratory tract depends upon the site at which the fiber makes initial contact, through which it migrates, where it deposits, and the route through which it is cleared. Persistence of fibers in lung tissue influences the severity of lung disease. The pulmonary deposition and clearance of inhaled fibers is a major determinant in understanding the health outcome of environmental and occupational exposures to these materials. Current microscopic methods of fiber analysis result in disruption of fiber orientation relative to lung structures and may influence our understanding of fiber toxicity within lungs.

The purpose of this study was to examine the in situ pulmonary fate of respirable fibers in lungs using simultaneous nonspecific fluorescent tissue staining and reflected light confocal microscopy. Serial optical sections were recorded using a Sarastro 2000 confocal laser scanning microscope (Molecular Dynamics, Inc.) optimized for reflected light imaging.