bluuebunny/crossref_metadata_2025 huggingface dataset:
An Investigation of Al-Rich Alloys in the Al-Cr-Ru System
Authors: Compton DN , Cornish LA , Witcomb MJ
Published: July 2020

Many aerospace components that operate in aggressive environments make use of coating techniques for protection. One of the alloy systems used in these coatings is Al-Cr-Ru, with typical alloy compositions between 20-35 at.% Al and 20-35 at.% Ru. Alloys with a higher Al content may provide protection through an aluminium oxide (AI2O3) scale which is resistant to high-temperature oxidation and corrosion. However, Al-rich alloys in the Al-Cr-Ru system have not been thoroughly investigated. Previously, the phase boundaries of the binary phases, except AI9Cr4, into the ternary were established. The two ternary phases (Ternary 1 and Ternary 2) were identified, although their phase boundaries were unclear. Thus more alloys have been studied to enable the liquidus surface, the solid phase projection and the 600°C isothermal projection to be drawn.

As-cast alloys were examined metallographically in the scanning electron microscope. The phases present were confirmed by X-ray diffraction, and the compositions obtained by energy dispersive Xray spectroscopy.
SEM Characterization of Hydrogenated Nickel
Authors: Tavares SSM , Lafuente A , Miraglia S , Fruchart D , Lambert B , Pairis S
Published: July 2020

The insertion of hydrogen in metals promotes severe modifications of physical and mechanical properties. in the case of nickel, hydrogen induces intergranular cracking [1] and decrease of ferromagnetism [2]. Hydrogen occupies the octahedral interstices of the fee structure promoting cell expansion. Large amounts of the fcc (β hydride may be produced by high pressure hydrogenation [3] or electrolytic charging [4]. The H/Ni relation (x) in the P hydride range from 0.6 to 1.0, depending on the method and conditions of hydrogenation. The β hydride is known to be metaestable at room temperature and normal pressure [5].

In this work, a thin foil (0.02mm thick) of high purity nickel was hydrogenated by electrolytic charging in a 1N H2SO4 solution with 20 mA/cm2 by 24 hours. AS2O3 was used as catalyst in a concentration of 5xl0−5mol/l. The hydrogenated samples were analysed by X-ray diffraction and SEM immediately after and 4 hours after the charging (room temperature aging).
EFTEM Elemental Mapping of Particles Frozen in Amorphous Solutions
Authors: Bovin J O
Published: July 2020

The preparation of frozen amorphous nano-meter thin films of solutions containing particles, and imaging with energy filtered TEM, opens for the first time the possibility to map the elemental distribution in solids interacting with liquids. The future possible areas of research in solution include: dynamic of crystal growth processes, adsorption mechanisms, ion exchange, structure determination of nano-sized solids in equilibrium with different solvents, etc.

The sample preparation uses a controlled-environment vitrification system. Solidification of the liquid phase was achieved by plunging the solution, suspended in the holes of a lacy carbon on a copper grid, into liquid ethane (-174 °C). The specimen was transferred into the microscope by an Oxford CT3500 cryo-holder. The specimen temperature in the microscope column can be kept at -183 °C. The thickness of the vitrified film's, including the particles, should be about 50-100 nm or preferably less. The Philips CM120 BioTWIN Cryo microscope, here used for cryo-EFTEM, has a focal length of 6 nun and a structural resolution of 0.4 nm.
High Spatial Resolution Surface Analysis of Zeolite Catalysts in the Low-Voltage FE-SEM
Authors: Liu Jingyue
Published: July 2020

High spatial resolution chemical microanalysis of heterogeneous catalysts is traditionally done in transmission electron microscopy or scanning transmission electron microscopy (TEM/STEM) instruments. A major limitation of TEM/STEM techniques is, however, the stringent requirement of samples that can be examined: useful information can be extracted from only very thin areas of a sample. The preparation of suitable TEM samples may also pose a major problem for observing certain types of commercial catalysts, for example, beads, powders, or cylinders that are frequently used in catalytic reactions. These limitations preclude the application of TEM/STEM techniques to extracting information about the surface properties of thick or bulk catalyst samples.

With the recent development of high-resolution, field-emission scanning electron microscopes (FESEM), bulk samples can now be examined at a nanometer or sub-nanometer spatial resolution. At low incident beam energies, not only the emitted SE signal is more surface-sensitive but also charging of non-conducting materials is significantly reduced.
The Improved Passivation of Aluminum and Structure of Amorphous Alumina Formed on Aluminum During Oxidation in Various Environments
Authors: Zhou G -W , Kuznetsova A , Bhardwaj M D , Yates J T , Yang J C
Published: July 2020

Nearly all metals form a passivation film due to oxidation in air at ambient temperatures, that acts as a diffusion barrier to protect the materials from further corrosion. Aluminum demonstrates excellent passivation behavior due to the formation of a protective amorphous alumina film during exposure to air at ambient temperatures. However, H. Ebinger and J. Yates discovered that the passivation of aluminum can be significantly improved by artificial oxidation. Both electron-beam induced oxidation in water vapor and oxidation in ozone atmospheres3 showed higher impedance in electrochemical impedance spectroscopy measurements to anion diffusion than the thermally grown oxides. To understand the nature of this beneficial passivation, we probed the microstructure of these amorphous oxide films by transmission electron microscopy (TEM).

The oxide films were grown on a polycrystalline Al substrate. The Al substrate was cleaned with a sputter cleaner inside a UHV (ultra-high vacuum) system.
Multi- and Single-Walled Nanotubes in the B-C-N System Studied by HRTEM and EELS
Authors: Bando Y , Golberg D , Bourgeois L , Kurashima K , Sato T
Published: July 2020

Discoveries of C multi-walled (MWNTs) and single-walled (SWNTs) nanotubes opened up a wide horizon for applications of these nanostructures as electronic and structural materials. Later on, it has been realized that the nanotubular structures are formed in other layered compounds, e.g. in the B-C-N materials. However, in contrast to the C-based nanotubes whose synthesis parameters are well-established, synthesis of B- and N-doped C and pure BN nanotubes is a challenging issue. The present paper reports on large-scale synthesis and detailed HRTEM and EELS characterization of nanotubes in the B-C-N system.

MWNTs and SWNTs of B-C-N and BN were produced from C nanotube templates via a substitution chemical method through oxidation by B2O3, in a flowing N2 atmosphere at 1573- 1773 K. HRTEM of a product was carried out using a high-resolution field emission transmission electron microscope JEM-3000F (JEOL) equipped with a parallel EELS detector Gatan 666 and an ultra thin window Si(Li) EDS detector.
Effect of Extracellular CA on the Phosphorylation of Myosin Binding Protein C. In Cardiac Muscle and the Phosphorylation on Force Generation
Authors: Winegrad S , Kulikavskaya I , McClellan G
Published: July 2020

The affinity of the binding sites on troponin C (TNC) for Ca is sensitive to the state of phosporylation of troponin 1 (TN1). Two and possibly three other myofilament proteins can be phosphorylated by physiological reactions: the mosin binding protein C (MyBP-C), the regulatory light chain of myosin (RLC), and the tropomyosin binding subunit of troponin (TNT). In MyBP-C, the phosphorylation sites are specific for cardiac muscle, an occurrence that suggests a function unique to cardiac muscle. Phosphorylation of MyBP-C and RLC can be produced by Ca regulated kinases present in the myofibrils. Phosphorylation of RLC produces an increase in Ca sensitivity of contraction at submaximal concentrations of Ca without alteration of the maximum Ca activated force (Fmax). Absence of contractile activity decreases phosphorylation of RLC. One to two hours of quiescence in normal extracellular Ca reduces phophorylation substantially, and the level rises slowly when contractile activity is resumed.
Modulation of Striated Muscle Function is Reflected by Thick Filament Structure.
Authors: Levine Rhea JC , Kulakovskaya Irina , Lee Sweeney H , Winegrad Saul , Yang Zhaohui
Published: July 2020

In mammalian skeletal and cardiac muscles, regulation of activity occurs when calcium binds to troponin on thin filaments, which ultimately results in exposure of myosin-binding sites on actin. However, modulation of contractile function, affecting such parameters as calcium sensitivity, the rate of rise of tension, the expression of maximum tension and/or the rate of onset of relaxation, is also calcium dependent. It is, in part, a property of the thick filament itself and its component myosin and/or accessory proteins. Among these are phosphorylation of myosin regulatory light chains or light chain 2 (RLCs; LC2) and in cardiac, but not skeletal fibers, phosphorylation of myosin-binding protein C (MyBP-C).

Gentle methods of separating thick filaments from small tissue specimens, subjected to various experimental protocols designed to explore the functional parameters of such modulatory activities, allow examination of any accompanying structural changes.
Progress in Aberration-Corrected STEM
Authors: Dellby N , Krivanek OL , Lupini AR
Published: July 2020

Electron probe formation in a scanning transmission electron microscope (STEM) has two properties that maximize the benefits of spherical aberration correction: the smallest and brightest probes are formed when all the geometric aberrations are set to zero, and the size of the probe is not greatly affected by the presence of chromatic aberration. This contrasts with the case of conventional, fixed-beam TEM (CTEM), in which optimized phase-contrast imaging demands a non-zero spherical aberration coefficient (Cs), and chromatic aberration constitutes a major resolution limit. As a result, a consensus is presently emerging that the benefits of aberration correction will be felt most strongly in STEM.

Our efforts in Cs-corrected STEM have progressed from a proof-of-principle Cs corrector [1] to an optimized second-generation design [2]. The corrector in both cases is of the quadrupole-octupole type. The second-generation corrector uses separate quadrupoles and octupoles, and concentrates on maximizing the octupole strength.
Towards Z-Contrast Imaging in an Aberration-Corrected STEM
Authors: Pennycook S J , Rafferty B , Nellist P D
Published: July 2020

The demonstration of an aberration corrector for the STEM promises enormous improvements in the contrast and signal to noise ratio of Z-contrast images, with similar benefits for atomic column EELS. Here we show that the limiting resolution for a zone axis crystal will become not the probe, as in the case of isolated atoms, but the Is Bloch states. In fact, the Z-contrast image becomes a direct image of the Is Bloch states with limiting intensities for large thicknesses roughly proportional to Z The potential benefits for the (STEM) appear to far exceed those for the conventional TEM. Some of these benefits are intrinsic to incoherent imaging: the lack of interference artifacts and the potential factor of two improvement in image resolution were first pointed out by Lord Rayleigh. This improved resolution has been demonstrated by the achievement of sub-ingstrom information transfer in the VG Microscopes HB603U, and the resolution advantage will still apply after aberration correction.
The Case For 0.1eV EELS in a 1Å STEM
Authors: Batson RE
Published: July 2020

Semiconductor devices are rapidly heading towards nanometer sizes, with dielectric gate oxides already in the 2-3nm thickness range and transistor channel lengths of order 10-20nm. There is good reason to believe, therefore, that physical limits imposed by atomic level granularity will dominate operation of semiconductor devices in the future. Thus, recent work has identified a physical limit for the thickness of SiO2 in order to maintain its insulating character. [1] On the other hand, new opportunities are created, based on new behavior at the atomic level. In the presence of very high local electric fields, for instance, the local electronic structure can change from insulating to conductive, forming a very small, very fast “Mott” transistor. [2] In a single molecule having a localized electronic level which is positioned well with respect to a conducting environment, single electron transistor operation may be possible at room temperature. [3]
Comparison of Multislice Computer Programs for Electron Scattering Simulations and The Bloch Wave Method
Authors: Koch C , Zuo JM
Published: July 2020

As the demand for quantitative analysis of Transmission Electron Microscope (TEM) images and diffraction patterns increases, questions arise about the reliability of computer simulations using different software packages and algorithms that are used for comparison with the experiment. Here, we compared five multislice programs, which are (with the exception of Cerius2) freely available, with each other and also a Bloch wave code. Since multislice method propagates the electron beams through the crystal slice by slice, the development of differences between the programs can easily be seen by comparing amplitudes and phases of different beams vs. thickness (Pendelloesung plot). We calculated Pendelloesung plots for InP [001] in zone axis and tilted beam orientations and the Si [111] forbidden reflections using the following codes: Cerius2, NCEMSS, Autoslic3, Multis4, EMS5 and an updated Bloch wave code written by J.M. Zuo4.
Diffraction Measurement Of Local Lattice Parameters Using a Nanometer Sized Probe in STEM for Interface Studies
Authors: Zuo J M
Published: July 2020

In the annual dark field (ADF) imaging mode, diffraction intensities inside the ADF detector cutoff angle are discarded. This results a significant loss of the available information. By simultaneous recording the diffraction patterns, we can gain additional information about the specimen, while the ADF image gives the precise position of the probe. This paper describes how to extract the local lattice parameters or to measure the strain field from the zero diffraction disk. The accurate measurement of strain field close to an interface provide the complementary information about the composition and the structure of the interface. An example is the oxygen deficiency in high Tc superconductor of YBa2Cu3O7-δ. The level of oxygen deficiency is too small to be detected by x-ray spectroscopy but affect the lattice parameters significantly that can be experimentally measured [1].
Z-Contrast Imaging: Quantitative Aspects of the Dynamical Object Function.
Authors: Rafferty B , Pennycook S J , Nellist P D
Published: July 2020

In this paper, we use a Bloch wave approach to show that the elastically scattered electrons from neighbouring atomic columns in a zone-axis oriented crystal contribute incoherently to a Z-contrast image regardless of the fact that we have coherent dynamical scattering from a stationary lattice with no absorption. This incoherent nature of the elastic scattering means that through the filtering of the ls-type Bloch states by the detector geometry we approach the Rutherford Z2 dependence of the column intensity for sufficiently large inner detector angle. Thus, annular dark-field (ADF) imaging provides us with a direct incoherent structure image of the atomic-column positions in a zone-axis oriented crystal.

Bloch wave simulations were carried out at 300 kV for the 〈110〉 orientation of InAs (a = 6.06Å) with full, half and empty columns of In atoms. Calculations including 411-beams were carried out for each of the above structural configurations for a single incident partial plane wave vector parallel to the optic axis.
Energy-Filtering Techniques for Thick Samples
Authors: Kabius B , Seybold V , Hiller S , Rilk A , Zellmann E , Probst W
Published: July 2020

Imaging of sample regions with a thickness significantly larger than the extinction length and strong thickness variations introduces two major problems for transmission electron microscopy (TEM) : (i) inelastic scattering increases the energy width of the transmitted electrons and therefore the resolution decreases (ii) the contrast differences caused by thickness variations can be higher than the dynamic range of the detector system.

Both problems can be solved by using energy filtering techniques. The advantage here is that for energy filtered imaging the resolution limit is not determined by the sample thickness but by the width of the energy selection aperture. Fig. 1 shows three envelope functions of the temporal coherence calculated for different values of the energy width. The functions were plotted for an acceleration voltage of 200 kV and a high voltage stability of 2 ppm.
Geological Applications of Electron Energy-Loss Spectroscopy
Authors: Garvie Laurence AJ , Buseck Peter R
Published: July 2020

EELS with a TEM is an established spectroscopic technique that is used to provide both qualitative and quantitative chemical information. Analysis of EELS spectral shapes provides information on the coordination, oxidation state, and spin states of atoms in minerals. Despite the availability of parallel EELS detectors for almost fifteen years, geological applications are relatively rare, mainly because of the high level of expertise required by the operator in both acquiring and analyzing the data. For example, core-loss edges can be difficult to see on the background and elemental quantification is not yet routine.

The goal of this review is to discuss the uses and interpretations of the EELS spectra of a range of minerals. We will focus on the interpretation of the electron-loss near-edge structures (ELNES) of the core-loss edges and concentrate primarily on: a) determination of the oxidation state of transition elements and other metals, and b) identification of local anion and cation coordinations. In addition, we will explore the potential of ELNES as a bonding probe.
Atomic Structure and Bonding of Epitaxial CU Films on (1120) A-Al203
Authors: Scheu C , Stein W , Schweinfest R , Wagner T , Röhle M
Published: July 2020

Thin Cu films were grown on single crystalline α-Al2O3 by molecular beam epitaxy at a substrate temperature of T = 800°C. The nominally 100 nm thin film consists of islands, which have diameters of 0.5-1 μm. High-resolution transmission electron microscopy (HRTEM) and electron energy-loss spectroscopy (EELS) were applied to obtain information about the atomic and electronic structure of the interface. HRTEM studies were performed on the Jeol JEM ARM 1250 operated at 1250 kV (point resolution of 0.12 nm). Analytical studies were conducted on a dedicated scanning TEM (VG HB 501) operated at 100 kV and equipped with a parallel EELS (Gatan 666).

HRTEM of the Cu/ Al2O3-interface shows an atomically abrupt interface and reveals an epitaxial orientation relationship (1120)s[0001]s || (111)Cu <211>Cu (S denotes sapphire) (FIG.l). Close-packed planes and directions in both crystals are parallel to each other resulting in misfits of 2% and 7% in <211>Cu- and <110>Cu-directions, respectively. The interface is not coherent, but in both directions no misfit dislocations are detectable.
The Effect of Local Symmetry on Atomic Resolution EELS Near-Edge Structures: Predictions for Grain Boundaries In NiAl
Authors: Pankhurst D A , Botton G A , Humphreys C J
Published: July 2020

It has been demonstrated that electron energy loss spectrometry (EELS) can be used to probe the electronic structure of materials on the near-atomic scale. The electron energy loss near edge structure (ELNES) observed after the onset of a core edge reflects a weighted local density of final states to which core electrons are excited by fast incident electrons. Lately ‘atomic resolution EELS’ and ‘column-by-column spectroscopy’ have become familiar themes amongst the EELS community. The next generation of STEMs, equipped with spherical aberration (Cs) correctors and electron beam monochromators, will have sufficient spatial and energy resolution, along with the superior signal to noise required, to detect small changes in the ELNES from atomic column to atomic column.

Core loss ELNES provides information about unoccupied states, but the structure observed in spectra is sensitive to changes in the underlying occupied states, and thus to the bonding in the material.
Advanced Instrumentations for Interface Studies by Electron Energyloss Spectroscopy (EELS, ELNES and ESI)
Authors: Rühle M , Elsässer C , Scheu C , Sigle W
Published: July 2020

Most materials used in technology are polycrystalline. Therefore, the properties of the internal interfaces often control the properties of the materials (interface-controlled materials). In single phase polycrystalline materials, grain boundaries are the internal interfaces (homophase boundaries) of interest, whereas in composites interfaces between different components (heterophase boundaries) play a crucial role. It is of great importance to investigate the structure, composition and bonding of the different interfaces. The atomistic structure of specific interfaces is obtained by high-resolution transmission electron microscopy studies, whereas analytical electron microscopy (AEM) investigations produce information on the composition of interfaces. AEM studies include energy-dispersive X-ray spectroscopy (EDX) as well as electron energy-loss spectroscopy (EELS). From the energy-loss near-edge structure (ELNES) of ionization edges measured by EELS, information on the local electronic structure at interfaces can be obtained. Information on bonding and its modifications by segregated atoms can be extracted from the ELNES studies.
Determination of the Electronic Structures of Screw and Edge Dislocations in Gan Using Atomic Resolution EELS
Authors: Arslan I , Xin Y , James E M , Sivananthan S , Browning N D , Pennycook S J , Omnes F , Beaumont B , Faurie J-P , Gibart P
Published: July 2020

In recent years, GaN and its alloys have been the subject of an intense global research effort to develop its optoelectronic properties in the blue-green region of the spectrum. Of particular interest has been the fact that despite a high density of threading dislocations, on the order of 108 to 1010 per cm2, thin film devices retain their ability to emit light. The origin of this behavior remains unclear, and it has even been suggested that reducing the number of defects by employing different growth techniques does not necessarily increase the crystal's lasing abilities. As research is now aiming to grow GaN on silicon (silicon has a large lattice-mismatch to GaN) in order to develop an inexpensive LED technology, dislocations are likely to remain a major issue. It is therefore essential that we develop a fundamental understanding of the electronic structure of these defects, in order to determine their effect on the properties.
Angular - Resolved Electron - Energy - Loss - Spectroscopy of Perovskite Manganeese Oxide
Authors: Murooka Y , Tanaka N , Hibino M
Published: July 2020

Among perovskite manganese oxide systems, La1-xSrxMnO3, has been intensely investigated because of its interesting magnetic and electronic properties such as colossal magneto resistance (CMR). These properties are largely determined by the electronic structure of the valence electrons. The electronic structure of the electrons in the energy states near the Fermi level was probed by using electronic excitations of less than a few eV. Ordinarily, the information obtained about the energy states was integrated over all crystal orientations, and only few anisotropic systems were studied in terms of their orientation dependence. In the present study, we reported an orientation dependence of the plasmon dispersion, which corresponded to electronic excitations of 30eV and characterized the collective excitation of the valance electrons, on an isotropic system La,.xSrxMn03 (x=0.4) by angular-resolved electron energy loss spectroscopy (EELS).
Correlation of Fabrication and Structural/Electronic Properties of Carbon Nanotubes Using TEM/EELS
Authors: Reed B W , Sarikaya M , Dalton L R , Bertsch G F
Published: July 2020

Since their discovery, carbon nanotubes have been the focus of much research effort aimed at optimizing growth conditions, elucidating physical structure, and measuring electronic properties. Measurement methods have included high resolution techniques such as AFM, STM, TEM, and EELS, as well as surface and bulk spectroscopic techniques, such as XPS. Most investigations have been quite specific, centering on a small number of nanotubes formed under particular growth conditions and typically employing only one or two modes of analysis. Broader, more systematic studies are relatively rare, and it is the intent of the present work to help fill this gap. We combine results of high-resolution TEM imaging, electron diffraction, low-energy EELS, and carbon K-edge EELS to characterize a variety of nanotube samples, grown and annealed under various conditions.

The Carbon Nanotubes (Cnts) Are Made By The Dual, Pulsed-Laser Vaporization Method, And Purified With A Process That Involves Nitric Acid Reflux, Washing/Centrifugation Cycles, Hollow-Fiber, And Cross-Flow Filtration.
Electron Energy-Loss Spectroscopy (EELS) of Fe-Bearing Olivine and Laihunite (an Oxidized Olivine)
Authors: Xu Huifang , Fu Pingqiu
Published: July 2020

Laihunite that has distorted olivine-type structure with ferric and ferrous irons and ordered distribution of vacancies was first discovered in a high-grade metamorphosed banded iron formation (BIF) [1, 2]. The laihunite coexisting with fayalite (Fe-olivine), magnetite, quartz, ferrosilite, garnet and hedenbergite, formed in the process of oxidation of fayalite [2, 3]. The structure refinement of 1-layer laihunite shows P21/b symmetry and ordered distribution of vacancies in half M1 sites of olivine structure [2, 3]. Early high-resolution transmission electron microscopy (HRTEM) study and HRTEM image simulation of the 1-layer laihunite verified the structure refinement [4].

Specimens of weakly oxidized fayalite and laihunite containing fayalite islands collected from Xiaolaihe and Menjiagou of Liaoning Province, NE China, have been studied using selected area electron diffraction (SAED), high-resolution transmission electron microscopy (HRTEM), electron energy-loss spectroscopy (EELS), and X-ray energy-dispersive spectroscopy.
Reflection Extended Electron Energy Loss Fine Structure (REXEELFS) Study Of Damage Induced By Ar+ on Hopg (0001) Surface.
Authors: Duarte-Moller A , Espinosa-Magaña F , Martínez-Sánchez R
Published: July 2020

In recent years much attention has been paid in development of EXEELFS (EXELFS, EELFS) technique.Some people around the world focused their work in characterizing materials in both, reflection and transmission geometries [ 1-2]. These studies show that EXEELFS technique is a reliable way to obtain the local structure of these materials. Some authors have been done experiments to detect structural changes on the surfaces (epitaxial grown, small clusters grown, surface reconstruction, etc, ). In this paper we have done a systematical observation of the possible damage induced by the Ar+ ions on HOPG surface at different sputterin times

Experiments were taken at room temperature in a commercial UHV chamber for surface analysis, with a base pressure of 2.5 x 10-10 Torr. A PERKIN ELMER PHI-595 scanning Auger microprobe with single pass Cylindrical Mirror Analyzer. (CMA), and coaxial election gun which can operate from 1 KeV to 10 K eV, equipped with Ar ion gun system for cleaning surfaces was used.
3D Reconstruction of Na+, K+-ATpase from Tubular Crystals
Authors: Rice W J , Young HS , Martin DW , Sachs J R , Stokes DL
Published: July 2020

The Na+,K+-ATPase is a transmembrane protein, located in the plasma membrane of virtually all animal cells, which controls Na+ and K+ gradients. It is a member of the P-type ATPase family of ion pumps, a group of enzymes which pump ions against a concentration gradient, forming a phosphorylated intermediate during the pumping cycle. For each mole of ATP hydrolysed, 3 Na + ions are moved out of the cell and 2 K+ ions are moved into the cell. Unlike most other members of this family, which have one subunit, Na+, K+-ATPase is a heterodimer of α and β subunits. The a subunit consists of 1020 amino acids and has been predicted to have 10 membrane-spanning a-helices as well as a large cytoplasmic headpiece which forms the ATP binding and phosphorylation site. The α subunit, 300 amino acids in length, has one membrane spanning helix and has most of its mass located on the extracellular side of the membrane.
3D Reconstruction from STEM Images of Xanthine Dehydrogenase and Insulin Receptor: Refinements and Molecular Modelling.
Authors: Beniac DR , Luo RZT , Fernandes AB , Iwasaki T , Yip CC , Ottensmeyer FP
Published: July 2020

We have reconstructed the three-dimensional quaternary structure of the complete 480 kDa insulin receptor (IR), complexed with Nanogold - labeled insulin, and the 290 kDa Xanthine Dehydrogenase (XDH). Both molecules were imaged by low-dose, low-temperature dark field scanning transmission electron microscopy (STEM). XDH and IR were both freeze-plunged in liquid ethane, and transferred to the STEM (VG HB 601) where they were freeze dried at -130°C. Reconstruction was carried out using the method of quaternion-assisted angular reconstruction (IQAD) as described previously. XDH was further refined by an iterative process in which the IQAD produced volume was used as a reference for further refinements. Separate reconstructions of two sets of half the images indicated an inter-reconstruction resolution of 20 Å and 9 Å by phase residual criteria for the IR and XDH reconstructions, respectively.
Cryo-Electron Microscopy Training at the Wadsworth Center
Authors: Grassucci Robert A , Frank Joachim
Published: July 2020

Training of students, postdocs and scientists in the techniques and instrumentation of Cryo-electron microscopy has many challenges. This is especially the case at the Wadsworth center where there are a variety of techniques as well as instruments to choose from, each of them having certain nuances that need to be recognized before they can be fully taken advantage of. There are also users with many levels of experience that need to be trained to use the equipment and techniques effectively. For this reason we have chosen to incorporate many of the protocols which are used into an internal web page. The web browser is a very effective tool for conveying detailed information on a variety of levels.

A novice user is asked to go through the EM training web page (Figure 1) and then select the Philips EM420 use link to get a feel for the steps that will be involved to set up and operate the microscope.
Macromolecular Structure Visualization Tools at NCMI
Authors: Dougherty Matthew , Chiu Wah
Published: July 2020

Sophisticated tools are needed to examine the results of cyro-microscopy. As the size and resolution of three dimensional macromolecular structures steadily improve, and the speed at with which they can be generated increases, researchers are finding they are inundated with larger datasets and at the same time are compelled to expediently evaluate these structures in unforeseen ways. Integration of EM data with other types of information is becoming necessary and routine; for example X-ray data, 3D EM reconstructions, and theoretical models, must be evaluated in concert to discount or propose hypothesis. To create such tools, the developer must take into account not only the empirical and theoretical possibilities, but also they must master the human factors and computational limits. During the last five years, the National Center for Macromolecular Imaging (NCMI) has progressed from a remedial 3D visualization capability to a collection of visualization tools allowing researchers to focus on the discovery phase of biological research.
Bacteriophage PRD1 Capsid Structure: Iterative Combination of Threedimensional Electron Microscopy and X-Ray Crystallography
Authors: Martin Carmen San , Burnett Roger M , Haas Felix de , Heinkel Ralph , Rutten Twan , Fuller Stephen D , Butcher Sarah J , Bamford Dennis H
Published: July 2020

PRD1 is a ds-DNA bacteriophage from the Tectiviridae family with an unusual structural feature: the viral genome is enclosed by a protein-rich membrane, which is in turn enclosed by an external icosahedral protein shell (capsid). Three-dimensional reconstructions from cryo-electron microscopy (cryo-EM) images have revealed the structure of the PRD1 capsid at moderate resolution (28 Å), while X-ray crystallographic studies have recently provided a high resolution (1.85 Å) picture of the major coat protein, P3. We have now combined these results from different imaging methods to obtain a more detailed understanding of the virion organization. The combination has been made in a cyclic process: a preliminary fitting of the atomic structure of P3 to each one of its independent positions in the cryo-EM maps of the capsids provided initial models that could be used to improve the reconstructions; the refined maps then served as a base frame for an optimized fit. This process allows us to study the viral particle structure at “quasi-atomic” resolution.
Cytoskeleton-Organelle Interaction: Higher Plant Chloroplasts Are Contained In Actin Baskets And Attached To Actin Filaments And Bundles
Authors: Kandasamy MK , Meagher RB
Published: July 2020

Plant organelles, including the dominant chloroplasts, migrate intracellularly on cytoplasmic strands (Fig. 1A-D). The chloroplasts in the leaf cells orient and redistribute in response to light to ensure maximum photosynthetic productivity. Their orderly distribution is also essential for proper transmission of organelle genome during cell proliferation. The movement and positioning of chloroplasts have been suggested to be mediated by the actin and tubulin-based cytoskeleton in green algae and higher plants. However, the actin structures controlling these processes have not been clearly delineated because of the difficulty in preserving and detecting the fine actin filaments in plant cells using conventional fixation methods and currently available antibodies.

We investigated the role of the actin cytoskeleton in the regulation of chloroplast movement and positioning by studying: 1) the structural relationships of microfilaments and chloroplasts in leaf cells of Arabidopsis; and 2) effects of an anti-actin drug, Latrunculin B (LAT-B), on intracellular distribution of chloroplasts.
Routine High Resolution Cryo SEM Applied to Medical, Cosmetic, Health Care, Pharmaceutical and Food Industries.
Authors: Robins Alan
Published: July 2020

The value of a Cryo SEM system, attached to a conventional SEM, has already been demonstrated in the biological, pharmaceutical, oil, paint, plastics and food industry. Specimens are first rapidly frozen to below -160°C, transferred under vacuum to a cryo preparation chamber, fractured and examined at low KV (uncoated ) in the SEM. The sample is then usually etched, sputter coated and finally examined at 5-15KV. On conventional microscopes, successful cryo images can be obtained at 30,000 - 50,000X magnification at high KV.

With the invention of field emission gun technology, much higher resolution is now achievable at a lower KV. This allows higher resolution information to be visualised from the surface of the sample. To allow this successful resolution, with the low atomic number samples mentioned above, we have to put down a fine grain, artefact free coating of high atomic number material to prevent charging and help reduce beam penetration.
Immunoprobe Localization by Correlative Microscopy: How Much Resolution is Enough?
Authors: Calarco Patricia G
Published: July 2020

With the advent of new ways to image biological material, to tag biological molecules, and to prepare samples, much progress has been made in understanding cellular and subcellular function without resorting to classical electron microscopy. Newer ways to image include the use of microscopies such as: differential interference, video, confocal, near field scanning optical, and magnetic resonance imaging. The use of tags such as cell-permeant organelle-specific markers and green fluorescent protein has further increased our ability to vision subcellular events in living cells, providing us with functional correlations of gene activity and cellular function in a number of biological systems. Techniques such as high pressure freezing coupled with freeze substitution have expanded the range of tissues and organisms that can be optimally preserved and are changing our understanding of cellular fine structure. However, even when electron microscopy is mandated, 1-2 angstrom resolution is rarely indicated except for investigations of molecular structure.
Immunoelectron Microscopy of Keratinocytes: an Improved Protocol for Flat Embedding of Cultured Cells Using Lowicryl K4M
Authors: Bauer C , Vasioukhin V , Yin M , Fuchs E
Published: July 2020

In cell culture models various and distinct manipulations can be performed in a defined environment. This makes cell cultures very popular for immunohistochemical studies. Such studies are mostly performed at the light microscopic level where fluorescent probes and confocal microscopy provide detailed insights into the distribution and localization of antigens inside cells. In many such cases further studies at the electron microscopic level would give additional information and an often more detailed view. As compared to light microscopy not only is the resolution much higher, but also and even more importantly labeling information is completed with a wealth of cytological details.

This said it is surprising that studies on cell cultures using immunoelectron microscopy are rarely seen. Even more rare are reports in which monolayer cells are fixed and processed in situ without prior trypsinization. Such studies are essential though when cytoarchitecture is of importance or especially when cell-cell adhesion is an issue.
Nucleation of Proeutectoid Ferrite on Complex Precipitates in Austenite
Authors: Furuhara Tadashi , Yamaguchi Jun , Maki Tadashi
Published: July 2020

Proeutectoid ferrite (bcc α) nucleation on the inclusions and precipitates dispersed in austenite (fee γ), denoted as intragranular ferrite transformation, has been used to refine the microstructure in the heat affected zone to improve the toughness of low and medium carbon steels. It is currently considered that Bl(NaCl)-type complex inclusions/precipitates (e.g. oxide, sulfide, carbide, nitride) are promising ones as ferrite nucleation sites. The present study aims to study the ability of various complex inclusions/precipitates in austenite as nucleation sites in proeutectoid ferrite transformations by standard and analytical electron microscopy.

Table 1 shows the chemical composition of Fe-2Mn-0.2C hypoeutectoid steels with various alloying element additions to change the inclusions/precipitate in austenite. Steel A contains a large density of MnS with the sulfur addition of 470ppm. Steels B and C also contain similar dispersion of MnS as Steel A.
Phase Stability in Cast HP Austenite After Long-Term Ageing
Authors: Kenik EA , Maziasz PJ
Published: July 2020

Casting of high temperature austenitic alloys is often used to form components and structures required in the chemical industry. Alloy HP is a Nb-stabilized austenitic alloy for such applications. High carbon levels are selected in order to drive the formation of coarse, intergranular precipitates of various carbides. These precipitates provide resistance to high temperature creep by inhibiting grain boundary sliding. While these precipitates are present in the cast material prior to high temperature exposure, it is the stability of these second phase particles during ageing that determines the long-term creep resistance and lifetime of stressed components. This study deals with the phase distribution in a centrifugally-cast HP component from a steam superheater tube in a styrene furnace, which experienced temperatures from 927°C to 1066°C or more for over 105,000 h.
TEM of Phase Transitions in Tridymite and Cristobalite Based Materials.
Authors: Tendeloo Gustaaf Van
Published: July 2020

We have determined the structure of the paraelectric phase of BaAl2O4, which is a stuffed tridymite, by different TEM techniques and we will describe the phase transition between the ferroelectric room temperature phase and the paraelectric high temperature phase. We have also obtained HREM images of the higly radiation sensitive acristobalite phase of (Si0,9 Ge0,1)O2 and analysed the extended defects in this material.

The stuffed tridymite BaAl2O4 is ferroelectric at room temperature and undergoes a paraelectric-ferroelectric (PEFE) phase transition. The transition is reversible, takes place over a wide temperature range (400K-670K) and has a dynamical character. BaAl2O4 is easily obtained by solid state reaction of BaCO3, and A12O4,. The stoichiometric amounts of the initial reagents were mixed, grinded in an agate mortar under acetone and pressed into a pellet. The pellet was annealed in alumina crucibles at 1000 °C and 1300 °C for 40 h in air and furnace cooled.
Characterization of Interphase Interfaces Developed During the Ordering Transformation (ε (A3) →τ (L10)) In Manganese-Aluminum Alloys
Authors: Yanar C , Wiezorek JMK , Radmilovic V , Soffa WA
Published: July 2020

Alloys based on the ferromagnetic τ-phase, which may be established in the Mn-Al system for near equiatomic composition [1], exhibit high magnetocrystalline anisotropy and coercivity and are of interest for advanced permanent magnet applications [2], Their technologically important properties depend strongly on the microstructure and defect structure development associated with the transformation from the disordered hexagonal (A3) ε-phase to the ordered tetragonal (L10) τ-phase. The structure, morphology and chemistry of the (ε/τ) interphase interfaces have been studied by methods of optical and electron microscopy (OM, SEM and TEM) in order to determine the nature of this technically important and scientifically interesting phase transformation. The optimization of processing-property relationships for this class of ferromagnetic materials requires a detailed understanding of the mechanisms facilitating the ordering process.

The τ-phase nucleates at prior ε-grain boundaries (ε-GB) and exhibits a serrated, faceted growth morphology (FIG. l).
TEM Analysis of Corrosion Products From a Radioactive Stainless Steel-based Alloy
Authors: Dietz NL , Keiser DD
Published: July 2020

Argonne National Laboratory has developed an electrometallurgical treatment process for metallic spent nuclear fuel from the Experimental Breeder Reactor-II. This process stabilizes metallic sodium and separates usable uranium from fission products and transuranic elements that are contained in the fuel. The fission products and other waste constituents are placed into two waste forms: a ceramic waste form that contains the transuranic elements and active fission products such as Cs, Sr, I and the rare earth elements, and a metal alloy waste form composed primarily of stainless steel (SS), from claddings hulls and reactor hardware, and ∼15 wt.% Zr (from the U-Zr and U-Pu-Zr alloy fuels). The metal waste form (MWF) also contains noble metal fission products (Tc, Nb, Ru, Rh, Te, Ag, Pd, Mo) and minor amounts of actinides. Both waste forms are intended for eventual disposal in a geologic repository.
Migrating Interfaces in Sapphire Bicrystals and Tricrystals
Authors: Ravishankar N , Johnson MT , Barry Carter C
Published: July 2020

The migration of grain boundaries in polycrystalline materials can occur under a variety of driving forces. Grain growth in a single-phase material and Ostwald ripening of a second phase are two common processes involving boundary migration. The mass transport in each of these cases can be related to a chemical potential difference across the grains; due to curvature in the former case and due to a difference in the chemistry in the latter case. The mass transport across grains controls the densification process during sintering. In the case of liquid-phase sintering (LPS), a liquid film may be present at the grain boundaries which results in an enhanced mass transport between grains leading to faster densification. Hence, in LPS, it is important to understand mass transport across and along a boundary containing a liquid film. The use of bicrystals and tricrystals with glass layers in the boundary can provide a controlled geometry by which to study this phenomenon.
Twinning Mlcrostructure and Charge Ordering in the Colossal Magnetoresistive Manganite Nd1/2Sr1/2MnO3
Authors: Luo Z P , Miller D J , Mitchell J F
Published: July 2020

Charge ordering (C.O.) in the colossal magnetoresistive (CMR) manganites gives rise to an insulating, high-resistance state. This charge ordered state can be melted into a low-resistance metallic-like state by the application of magnetic field. Thus, the potential to attain high values of magnetoresistance with the application of small magnetic fields may be aided by a better understanding of the charge-ordering phenomenon. This study focused on microstructural characterization in Nd1/2Sr1/2MnO3. In Nd1/2Sr1/2MnO3, the nominal valence of Mn is 3.5+. On cooling, charge can localize and lead to a charge ordering between Mn 3+ and Mn 4+. The ordering of charge results in a superlattice structure and a reduction in symmetry.

Thin foil specimens were prepared from bulk samples by conventional thinning and ion milling (at LN2 temperature) methods. The TEM work was carried out in a Philips CM30 at 300 kV with a Gatan LN2 cold stage, and a JEM 4000EX with a resolution of 0.17 nm at 400 kV for HREM observation.
Grain Boundaries and Interfaces in MoSi2 and MoSi2-SiC Composites and Their Effect on High Temperature Strength
Authors: Bailey GW , McKernan S , Price RL , Walck SD , Charest P-M , Gauvin R , Mitra R , Chiou W-A , Venugopal Rao A
Published: July 2020

Molybdenum di-silicides (MoSi2) based materials have a strong potential for high temperature structural applications due to high melting point of 2030°C, outstanding elevated temperature oxidation resistance and limited ductility above a temperature range of 1100-1300°C. The major shortcomings of MoSi2 for structural applications are its poor room temperature fracture toughness and low high temperature strength. Sustained efforts including reinforcing MoSi2 with ceramic reinforcements, alloying and in-situ processing, have been made to improve these properties. The purity of grain boundaries and interfaces, which in turn depends on the processing method plays a significant role in the high temperature properties and this paper aims to show that.

Intimately mixed Mo and Si powders (Mo:Si = 63:37 by weight fraction) were reaction hot pressed (“RHP“) in vacuum at 1500°C for 1 h, using a pressure of 26 MPa. During the hot pressing process, Mo and Si reacted to form MoSi2.
XTEM Study of the Microstructure of PZT Thin Films
Authors: Wang S X , Wang L M , Lin C L
Published: July 2020

Lead zirconate titanate (PbZrxTil-xO3, PZT) is one of the important ferroelectric materials for the storage elements of high-speed non-volatile memories. It also has much potential to be used in pyroelectric sensor, ultrasonic motor, and multiplayer ceramic capacitor.

PZT (Zr/Ti = 48/52) thin films were prepared using a metal-organic decomposition (MOD) process. The precursor solution used for PZT thin film preparation was based on lead acetate trihydrate, Pb(CH3COO)2; zirconium nitrate, Zr(NO3)4.5H2O; and titanium nbutoxide, Ti(nC2H9)4. 2-butoxyethanol was chosen as a solvent. A 30% excess Pb was added to the precursor to compensate for the loss of lead oxide during the annealing process. Acetic acid was used as a complexing agent for PZT solution to control the hydrolysis and condensation rates. The 0.3M precursor solution was spin-coated on the Pt(111)/Ti/SiO2/Si substrates for 20s at 3000 rpm. The deposited film was fired at 450 °C for 10 min and repeated five times to burn out the organics. The films were crystallized at 600 °C in air for 1 hr.