bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure determination of the incommensurate intercalation compound HgxTiS2 using TEM
Authors: Sidorov M. 
Published: June 2020

Although metal intercalated transition-metal dichalcogenides have been generally viewed as ionic compounds with guests occupying discrete lattice sites, the HgxTiS2 intercalates (1.24≥×≥0.00) have been recently discovered to have vastly different character, including essentially-neutral covalently-bound guests, superstoichiometric Hg uptake (x>1.00), complete thermal reversibility of the intercalation process and unusually complex structures. A combination of HREM and electron diffraction was used to determine the structure of the intercalates formed during the in situ deintercalation process. Digital Fourier image processing provided HREM image analysis and contrast enhancement.HgxTiS2 has a remarkable in-plane guest-layer structure, which is composition independent. It results from the presence of partially incommensurate monoclinic Hg and TiS2 sublattices, with common a and c axes and incommensurate b axes (a= 5.92 Å; bTis2 = 3.41 Å; bHg= 2.76 Å; c= 8.70 Å, and β= 96.5°). Figure 1a shows a typical c-axis SAD pattern from a thin crystal indicating the presence of two subsets of reflections incommensurate along b* direction. In the corresponding HREM images this gives rise to the 14.5Å structure modulation along b (Fig. 1b).
1 nm resolution x-ray elemental mapping using a 300kV field emission TEM
Authors: Murakoshi H. , Tsuchiya T. , Kakibayashi H. 
Published: June 2020

The characteristics of advanced semiconductor devices are affected by contamination due to impurity atoms with sizes at the nanometer level, so it is very important to evaluate such contamination with nanometer-level resolution. In order to cope with this task, we have developed an x-ray elemental mapping system, attached to a 300-kV FE-TEM, with an information limit of 0.11 nm.Both small spot size and sufficient probe current are necessary for high-resolution and highsensitivity x-ray elemental mapping. The elemental mapping is performed with the scanning transmission electron microscope(STEM) mode. For high-resolution STEM imaging, the objective lens works with high excitation as a condenser-objective single lens where the aberrations of the other illuminating lenses are demagnified to negligible level, allowing the extremely small spot size to be obtained. The probe current, however, decreases in proportion to the square of the demagnification of the illuminating system. In this study, the optimum illuminating condition for elemental mapping is examined.
State of the development of multipole correctors for a probe-forming system and a high-resolution 200kV TEM
Authors: Haider M. , Zach J. 
Published: June 2020

The development of modern high resolution electron microscopes has shown the emergence of new modern microscopes which are easy to operate and, more importantly, with which one can attain high resolution on a routine basis. However, the physical limit set by the inherent aberrations of electron lenses could not be overcome by simply optimising the geometry of the pole pieces. The only direct way to get rid of the aberrations of the round lenses is to use a corrector with which the resolution limiting aberrations can be compensated.For the observation of uncoated biological surfaces we started a project to develop a Low Voltage Scanning Electron Microscope (LVSEM). The main problem with using low energies is to design electron optics with which one can achieve high resolution in the range of 1 nm at energies of 1 keV and below. Hence, the two main axial aberrations of such a probe forming system: the chromatic and the spherical aberration Cc and C3, respectively, have to be considered as the limiting factors of the probe diameter. Therefore, the compensation of these two aberrations is the best choice as one does not want to run into other limitations if, for example, the geometry of the objective lens is scaled down in order to obtain small aberration coefficients.
Modeling and simulation of octahedral Pb inclusions in Al
Authors: Xiao S.Q. , Paciornik S. , Kilaas R. , Johnson E. , Dahmen U. 
Published: June 2020

Pb inclusions in Al have been extensively studied for their unusual melting/solidification behavior. Pb inclusions have a cube on cube parallel orientation relationship with the Al matrix and assume cuboctahedral shapes faceted on {111} and {100}. Al and Pb are both fcc structures but with very different lattice parameters: aAl = 0.405 nm, apb = 0.495 nm. Thus 5 Al spacings match approximately 4 Pb spacings giving rise to a moire pattern visible in HREM images.High resolution electron micrographs in the <110> zone axis orientation were recorded on the Berkeley ARM at an accelerating voltage of 800 kV. In this orientation the cuboctahedra project as truncated parallelograms as shown in Fig. 1. Although the four (111) interfaces revealed in Fig. 1 are imaged edge-on, the Al lattice overlaps the Pb lattice above and below, because the other four (111) interfaces are inclined. Therefore, even though the (111)Al lattice is clearly resolved, the determination of inclusion size is not straightforward because the contrast depends on defocus (Δf), particle size (s), depth of the inclusion in the matrix (z) and total sample thickness (t).
A hitchhiker's guide to microscopy and microanalysis using telecommunications, e-mail, and the Internet: part II
Authors: Zaluzec Nestor J. 
Published: June 2020

In this tutorial, we will update, review and demonstrate the means of finding and accessing resources of electronic information which are maintained by the Microscopy Society of America and related national/international organizations. During the course of this live demonstration over the Internet, we illustrate the use of Electronic Mail, Newsgroups, File Transfer Protocols, Gophers, and Information Servers using the World Wide Web protocols. Although the MSA electronic bulletin board system (BBS) has be recently discontinued, MSA has recently decided expanded it's role in other telecommunications areas. The procedures needed by individuals or organizations to access this wealth of information will be presented in detail. The following list of topics summarizes some of the areas which will be covered.Electronic Mail: (EMail) is textual communications which is sent over networks from one individual to another. Each user is assigned a unique address by the computer system administrator. The message composed of normal ASCII (text) characters which is sent from one computer to another.
Use of fluorescence in situ hybridization to study the arrangement of DNA sequences in normal and disease-related chromosomes
Authors: Trask Barbara J. F. , Massa Hillary , Friedman Cynthia , Esposito Richard , van den Engh Ger , Yokota Hiroki 
Published: June 2020

The sites of specific DNA sequences can be fluorescently tagged by fluorescence in situ hybridization (FISH). Different sequences can be labeled with different fluorochromes so that their arrangement can be studied using epifluorescence microscopy. The distances between points on the same or different chromosomes can be determined easily in a large number of interphase nuclei or metaphase chromosomes. A variety of probe types, ranging from single-copy sequences to highly repeated sequences can be employed. Our work has focussed on the analysis of hybridization patterns in two dimensions using conventional fluorescence microscopy.We have used FISH to study various aspects of genome organization that are difficult to study using other techniques. Examples of these applications will be presented.FISH is now the method of choice for determining the chromosomal location of DNA sequences. DNA sequences can be positioned in the genome with <1:1000 accuracy (to a 3-Mbp region within a 3000-Mbp genome). Through FISH, the cytogenetic, physical and genetic maps of chromosomes can be linked.
Changes in rat pituitary gonadotropes after immunization with peptides derived from the receptor for gonadotropon-releasing hormone
Authors: Petrusz P. , Grossman G. , Weaver C. 
Published: June 2020

Gonadotropin-releasing hormone (GnRH) is a neuropeptide which regulates hormone release from pituitary gonadotropes. The recently cloned pituitary GnRH receptor consists of a linear chain of amino acids in which seven transmembrane segments separate 4 extracellular and 3 intracellular (cytoplasmic) sequences. The rat receptor is approximately 90% homologous with that of the human.Observations made in several autoimmune diseases and experimental models suggest that anti-receptor antibodies can interfere with receptor function. The present studies were designed to test this hypothesis in female rats (n=9×3) after immunization with synthetic peptides whose overlapping sequences replicated all putative extracellular domains of the cloned human GnRH receptor (Table 1). The peptides (A-H) were conjugated to keyhole limpet hemocyanin and the conjugates were injected i.m. at monthly intervals for four months. A control group (K) received adjuvant only. Anti-peptide antibodies in the sera of immunized rats were detected by ELISA. Recognition of the “native” GnRH receptor was tested in immunocytochemistry on normal pituitary and brain tissue.
Suitability of zinc-based bioceramic for repair of bone defects
Authors: Taylor C. , Mehling B. , Longo A. , Snead D. , Reynolds D. , Bajpai P. , Barre P. 
Published: June 2020

The advantages of a synthetic bone-graft substitute include reduction of risks due to immunological rejection and transmission of diseases, such as AIDS. A satisfactory synthetic material must be non-toxic, allow adequate re-vascularization, and be capable of bearing weight and tolerating strain. Our experiments using a resorpable, zinccalcium- phosphorous-ceramic oxide (ZCAP) in composite with malic acid, vitamin E, and gentamicin sulfate, indicate that this zincbased bioceramic implant fulfills the requirements of an osteoconductive filler between two fractured ends of rat femurs.Assessment of the suitability of ZCAP involved the following techniques :
1) Radiological examination showing the position of the implant, bridging of the defect with bone, and dissolution of the bioceramic.
2) Histology of serial sections indicating resorption of the ZCAP (a few granules remain after 10 weeks) and replacement by endochondral ossification.
3) Scanning electron microscopy revealing that the intact ZCAP first becomes surrounded by fibrous tissue and then infiltrated by cell processes.
Microstructural morphology of sphingolipid dispersions as investigated by freeze-fracture EM
Authors: Kulkarni Vitthal S. , Anderson Wayne H. , Brown Rhoderick E. 
Published: June 2020

The biological significance of the sphingomyelins (SM) and monoglycosylated sphingolipids like galactosylceramides (GalCer) are well documented Our recent investigation showed tubular bilayers in the aqueous dispersions of N-nervonoyl GalCer [N-(24:lΔ15,cls) GalCer] (a major fatty acyl moiety of natural GalCer). To determine the influence of lipid head groups on the resulting mesophasic morphology, we investigated microstructural self-assemblies of N-nervonoyl-SM [N-(24:1 Δ15,cls) SM; the second most abundant sphingomyelin in mammalian cell membranes], 1- palmitoyl-2-nervonoyl phosphatidylcholine [PNPC] (the lipid species with the same acyl chain configuration as in N-(24: 1) GalCer) and also compared it with egg-SM by freeze-fracture EM.Procedures for synthesizing and purifying N-(24:1) GalCer, N-(24:1) SM, and PNPC have been reported . Egg-SM was purchased from Avanti Polar Lipids, Alabaster AL. All lipids were >99% pure as checked by thin layer chromatography. Lipid dispersions were prepared by hydrating dry lipid with phosphate buffer (pH 6.6) at 80-90°C (3-5 min), vigorously vortexing (1 min) and repeating this procedure for three times prior to three freeze-thaw cycles.
Ultrastructural analysis redefines light microscopic findings relative to morphological relationships among cells of the cerebral vasculature in the rat
Authors: Dimlich Ruth V. W. 
Published: June 2020

A previous light microscopic study determined that ~70% of all connective tissue mast cells (CTMCs) in the thalamus of the rat were adjacent to periodic acid-Schiff staining cells which also were ED2 positive therefore identified as a type of macrophage. Using transmission electron microscopy, the goal of the present study was to examine that association at the ultrastructural level and to determine the relationship of each of these cells to other components of the cerebrovasculature.Brains of anesthetized adult male Sprague-Dawley rats were fixed by intracardiac perfusion with paraformaldehyde and glutaraldehyde [2%:2.5% (phosphate buffer 0.1 M, pH 7.40 or 2%:2.5% for 5 min followed by 1%: 1.25% (phosphate buffer 80 mM, pH 7.4) for the remainder of the fixation]. Brains were sliced into ~1 mm sections and samples of thalamus were postfixed in OSO4 (1%, 0.1 M phosphate buffer), dehydrated, and flat embedded in LX112. Semi-thin (1 μm) and thin (60-90 nm) sections were cut and stained with toluidine blue and uranyl acetate/lead citrate respectively. Grids were viewed on a JOEL 100CXII electron microscope at 80kV.
Immunogold localization of HMB-45 antigen in pulmonary lymphangiomyomatosis
Authors: Minda J.M. , Dessy E. , Pietra G. G. 
Published: June 2020

Pulmonary lymphangiomyomatosis (PLAM) is a rare disease occurring exclusively in women of reproductive age. It involves the lungs, lymph nodes and lymphatic ducts. In the lungs, it is characterized by the proliferation of smooth muscle cells around lymphatics in the bronchovascular bundles, lobular septa and pleura The nature of smooth muscle proliferation in PLAM is still unclear. Recently, reactivity of the smooth muscle cells for HMB-45, a melanoma-related antigen has been reported by immunohistochemistry. The purpose of this study was the ultrastructural localization of HMB-45 immunoreactivity in these cells using gold-labeled antibodies.Lung tissue from three cases of PLAM, referred to our Institution for lung transplantation, was embedded in either Poly/Bed 812 post-fixed in 1% osmium tetroxide, or in LR White, without osmication. For the immunogold technique, thin sections were placed on Nickel grids and incubated with affinity purified, monoclonal anti-melanoma antibody HMB-45 (1:1) (Enzo Diag. Co) overnight at 4°C. After extensive washing with PBS, grids were treated with Goat-anti-mouse-IgG-Gold (5nm) (1:10) (Amersham Life Sci) for 1 hour, at room temperature.
Ultrastructural changes in the mouse placenta after administration of trichosanthin
Authors: Ooi V.E.C. , Lau C.F. , Yeung H.W. 
Published: June 2020

The root tuber ofTrichosanthes kirlowiiMaxim (Family curcurbitaceae) has long been used in Chinese traditional medicine as an abortifacient and in therapy for choriocarcinoma. The active principle of the root tuber extract was recently purified and characterized. It is a basic protein of 24 KDa and is named trichosanthin. Investigations on trichosanthin action showed that it affected directly on the placenta, selectively causing necrosis of the syncytiotrophoblasts of placental villi. The present study attempts to determine the initial action of trichosanthin and follow through from the earliest sign of histopathological and ultrastructural changes of the mouse placentae after administration of trichosanthin.Mature ICR female mice were used. On the tenth day of gestation, a single dose of trichosanthin was injected intraperitoneally. The dosage used was 0.1 mg of trichosanthin in physiological saline per 25 g body weight of the mouse. At various prescribed intervals after injection, the mice were sacrificed by cervical dislocation.
Adherence of enterohemorrhagic Escherichia coli in a beef system
Authors: Schwach T. S. , Zottola E. A. 
Published: June 2020

Microbiologists have traditionally studied pure cultures growing in laboratory media. Food microbiologists, interested in interactions between the food system, pathogen, and host have tried to extrapolate information in the same manner. However, clinical isolates readily lose virulence characteristics when repeatedly subcultured into laboratory media. Expression of many virulence factors, such as fimbriae, extracellular polymers and outer membrane adhesins are affected by growth environment; an environment which encompasses not only nutrient availability and growth temperature, but also physical surroundings, moisture, oxygen and pH levels, and the presence of competitive flora. The ability of an organism to adhere to a surface is a major virulence factor.Enterohemorrhagic Escherichia coli (EHEC) are one of five groups of enteropathic E. coli which cause intestinal disease world-wide. The most well known of this group, serotype O157:H7, has been implicated in major food-borne illness outbreaks primarily due to the consumption of undercooked hamburgers. They are found in the intestinal tracts of cattle, feces, hanging carcasses, and frozen ground beef. E. coli O157:H7 adheres to large intestinal epithelium with characteristic lesions and produces verocytoxins which damage internal organs, such as the kidney.
Microscopic study of the plerocercoid larva of Otobothrium (Trypanorhyncha)
Authors: Abdou N. , Heckmann R. A. , Gardner J. S. , Ashour A. A. 
Published: June 2020

This study represents the first scanning electron microscope (SEM) evaluation of cestode larvae infecting Red Sea fish. General structures of the larvae and different types of microtriches on the integument are described.Plerocercoids of Trypanorhyncha were collected from the mesenteries and liver of Cephalopholis oligostricta. The capsule of each larva was opened, the plerocercoid was removed and fixed in 10% formalin. Following buffer (pH. 7.3) wash, they were fixed in OSO4 12 hr, washed in buffer, immersed in 2% tannic acid 8 hr, washed in buffer, fixed again in OSO4 2 hr, buffer washed, dehydrated, critical point dried, and sputter coated with gold.The plerocercoids were identified as belonging to the genus Otobothrium. Each organism was divided into a scolex and body. The scolex consisted of two large bothria, each bothrium was nearly round in outline and possessed two circular invaginations on its posterior margin. On the apex of the scolex, four extended tentacles covered with hooks were observed (Fig 1).
Resolution and contrast enhancement on biological specimens by means of electron spectroscopic imaging (ESI)
Authors: Hezel U. B. , Bauer R. , Zellmann E. , Miller W. I. 
Published: June 2020

The main elemental constituents of biological material - C,H,N,O - are the same elements found in typical embedding materials. Because of this the contrast of unstained biological material is very poor. Additionally, electron scattering by low Z atoms is mainly inelastic resulting in unsharp images from the concomitant chromatic aberration.These effects have been delt with by employing stains of such heavy metals as Os, U, or Pb. These stains are for the most part located at the biological structures themselves and primarily scatter the electron beam elastically. Thus with ultra-thin (<80nm) heavy metal stained sections of biological material the contrast in the CTEM is very good and chromatic aberrations are negligable.
Quantitative analysis of freeze fracture morphology of mouse embryo cells treated with retinoids and phorbol esters
Authors: Fassel Theresa A. , Hui Sek-Wen 
Published: June 2020

Phenotypic changes in C3H/10T mouse embryo fibroblast cells, induced by retinyl acetate (RAC) or 12-0-tetradecanoylphorbol-13-acetate (TPA) treatments, were studied by freeze fracture electron microscopy. TPA accelerates transformation while RAC suppresses transformation in these cells.Unfixed cells on glass substrates were rapidly frozen in liquid propane by the sandwich method. Freeze fracture was carried out at -120°C and vacuum better than 5x10-7torr in a Polaron unit equipped with a Perkin-Elmer Ultek ion pump and Cressi ngton electron guns. Intramembraneous particle (IMP) detection and quantitation was done using a Cambridge Instrument Quantimet 920 image analyzer with a macroviewer attachment.
Probing the surface of cultured endothelial cells grown on dextran beads
Authors: Hogan Margaret E. 
Published: June 2020

Primary cultures of endothelial cells were grown on cross-linked dextran beads to allow electron microscopic observation of Antithrombin III (ATIII) binding.Busch and Owen demonstrated a heparin-like, stationary ATIII cofactor on the surface of bovine aorta endothelial cells. This stationary cofactor was found to have several functional properties in common with the anticoagulant glycosaminoglycans (GAGS) heparin and heparitin sulfate. The purpose of this study was to characterize this cofactor and try to determine more about its function.
Effect of osmium vapor on calcium loss during sectioning of freeze-dried, embedded tissue
Authors: McGuffee L. J. , Little S. A. 
Published: June 2020

Our laboratory has been using electron microscopic autoradiography to localize 45Ca in smooth muscle. We prepare the tissue for these studies by quick freezing against a copper mirror, freeze-drying at low temperature, exposing the dry tissue to osmium tetroxide vapors in vacuo, and infiltrating and embedding in Spurr resin.Two requirements must be met before one can examine the distribution of a soluble ion, such as calcium, using this, or any morphological technique. First, morphological perservation of the tissue must be sufficient to identify cellular organelles and membranes. This requirement can be met in smooth muscle by using freeze-dried Spurr embedded tissue. Second, the distribution of calcium must be representative of the in vivo distribution.
Electron microscopy of alpha-plutonium
Authors: Staudhammer K. P. , Johnson K. A. , Stevens M. , Medina W. J. 
Published: June 2020

During the past several decades metallurgists world-wide have sought for a reliable and reasonable method to characterize plutonium and its alloys via transmission electron microscopy. Metallurgically, plutonium (Pu) represents one of the most fascinating metals; it has six solid phases and contracts when melted.A number of workers over the years have tried to produce thin foils of plutonium, but the foils were later shown to have been completely converted to oxide. The primary problem has been in the preparation of electron transparent thin foils of a material having one of the highest atomic numbers that is highly oxidation prone, in addition to being radioactive. Advances in Pu metallography in the late 70's and early 80's produced a new series of electro-chemical thinning solutions modified for plutonium.
Quadrupole/YAG Coupling of a parallel-recording system to a commercial energy-loss spectrometer
Authors: Egerton R.F. , Crozier P.A. 
Published: June 2020

We have interfaced a Tracor DARSS detector head to a Gatan 607 energy-loss spectrometer to produce a parallel-recording system operating in the indirect-exposure mode. Magnetic quadrupole lenses were used to increase the electron-optical dispersion by a factor of at least 20. These quadrupoles had a large bore (2 cm) and were mounted outside the vacuum (see Fig.1) to allow easy relocation so that various electron-optical arrangements could be investigated.The most economical scheme requires only a single quadrupole, placed close to the spectrometer exit, operating from a virtual object and forming a non-inverted spectrum at the conversion screen.