bluuebunny/crossref_metadata_2025_split huggingface dataset:
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.
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.
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.
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.
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.
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.
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.