bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mapping Binding Sites of Potential Anti-Cancer Drugs on Tubulin
Authors: Li Huilin , Nogales Eva , Downing Kenneth H 
Published: July 2020

Abstract
Microtubules are involved in many activities within the cell that require highly dynamic activity. For examples, microtubules can grow and shrink as they explore the cell, and the entire microtubule cytoskeleton is restructured as cells prepare for division. Interfering with microtubule dynamics can have serious consequences for the health of the cell, especially in cells that are rapidly dividing. The result of disrupting the normal dynamics is generally an interruption of the cell cycle and consequent induction of apoptosis. This behavior has been exploited with a number of anti-cancer drugs that target tubulin, the main protein in microtubules. Drugs are currently in use that either stabilize or destabilize microtubules. Among the most widely used is Taxol, one of the microtubule stabilizing drugs. Because Taxol produces a range of serious side effects and a substantial fraction of patients treated with Taxol eventually develop resistance to the drug, there is an active search for other drugs that might be more selective and less prone to resistance.
Electron Crystallographic Structure of the Limulus Acrosomal Bundle at 20 Å Resolution
Authors: Sherman Michael B , Waller Guichy , Matsudaira Paul , Chiu Wah , Schmid Michael F 
Published: July 2020

Abstract
Limulus sperm contains a dynamic macromolecular structure that rapidly extends a 50-μum process called the true discharge. The core of this structure is a bundle of ordered filaments composed of a complex of actin, scruin and calmodulin. We have shown that small segments along the bundle can be treated as single crystals with a unit cell spacing of 144 × 144 × 766 Å. A tomographic reconstruction of the bundle was done from multiple tilt series of images to ∼40 Å resolution. To extend the structural determination of the bundle at a higher resolution, we have used electron crystallographic analysis of single images of the bundles preserved in vitreous ice. Furthermore, we did not employ any helical or crystallographic symmetry (other than PI) in the reconstruction procedure.
Acrosomal bundles from Limulus sperm cells were purified as described earlier. Images of frozen hydrated bundles were taken at 40,000x EM magnification in a JEOL 4000EX electron cryomicroscope using an electron dose of 6 - 10 electrons/Å2.
3D Reconstruction of Smooth Muscle A-Actinin by Cryo Electron Microscopy
Authors: Liu Jun , Taylor Dianne , Taylor Kenneth A 
Published: July 2020

Abstract
α-Actinin is an actin crosslinking protein identified in a wide variety of cells. Both muscle and nonmuscle isoforms of α-actinin have been characterized [1]. The molecule consists of two polypeptide chains that form a rod-shaped antiparallel dimer. Each polypeptide is composed of three distinct structural regions: actin-binding domain, four triple helical repeats that form a central rod, and a carboxyl terminal domain that contains two EF hand calcium-binding sites. Here we present the 3D structure of the smooth muscle α-actinin, as determined by cryo electron microscopy at 2.0 nm resolution.
Two dimensional crystals of chicken gizzard α-actinin were formed on positively charged lipid monolayer [2] and preserved frozen hydrated for TEM. The crystal has a unit cell dimension of a = 26.31 nm, b = 20.37 nm, γ= 107.10°, based on internal calibration against TMV.
Electron Microscopy of Myelin Basic Protein (MBP) Organized as Planar Arrays on a Lipid Monolayer Surface: Deimination of MBP Hinders Its Organizational Properties
Authors: Ishiyama N , Matharu P , Bates IR , Wood DD , Moscarello MA , Viner NJ , Harauz G 
Published: July 2020

Abstract
Myelin basic protein (MBP) is one of the principal constituents of the mammalian myelin sheath. It is a basic peripheral membrane protein in the major dense line and is believed to play a structural role in maintaining myelin stability through its close association with lipids and other proteins. Immune responses to MBP have been implicated in the pathogenesis of multiple sclerosis (MS), the most common autoimmune disease of the central nervous system in North America and Northern Europe. The correlation between the severity of MS and the deimination of arginyl to citrullinyl residues in MBP was well illustrated in the acute case of MS (Marburg type) that contained MBP with 18 out of 19 arginines citrullinated.
We have studied a recombinant hexahistidine-tagged murine MBP (rmMBP, 18.5 kDa isoform) by electron microscopy of the protein organized as planar arrays on lipid monolayers that consisted of the nickel chelating lipid, l,2-dioleoyl-.yn-glycero-3-[(N(5-amino-l-carboxypentyl)iminodiacetic acid)succinyl] (Nickel salt) (Ni2+-NTADOGS), and the filler lipid, liver phosphatidylinositol (PI).
Estimates of the Fourier Amplitude Decay of Electron Micrographs of Single Particles
Authors: Saad Ali , Ludtke Steven J , Jakana Joanita , Rixon Frazer J , Tsuruta Hiro , Chiu Wah 
Published: July 2020

Abstract
Several structures of single particles have been resolved to 7-9 Å using electron cryomicroscopy. This field is now poised to make the next step, to near atomic (3-4 Å) resolution. Signal to noise ratio is the critical factor determining the amount of data required for a structural determination at higher resolution. When properly weighted, signal to noise ratio is additive as image data is averaged coherently, however, this relies on perfect alignment of the noisy images. Typical refinement algorithms require as high a signal to noise ratio as possible for accurate alignment. We report a method, which allows accurate, routine determination of signal to noise ratio and other image parameters, both for data quality assessment and microscope quality tracking.
Figure la shows a typical 400 kV electron image of ice-embedded herpesvirus capsids. The incoherent sum of the Fourier transforms of particle images (Fig. lb) shows that the data contains information out to a resolution of 7 Å. When rotationally averaged, this power spectrum can be expressed as:
Advances in High Resolution Cryo-EM Studies: the Quartenary Structure of the 70S E.Coli Ribosome Revealed at 11.5Å Resolution.
Authors: Penczek P , Spahn ChMT , Agrawal RK , Gabashvili IS , Grassucci RA , Frank J 
Published: July 2020

Abstract
Three-dimensional cryo-electron microscopy (EM) of macromolecular assemblies with low or nonexistent symmetry in single-particle form is now recognized as a powerful, legitimate method of structure research. The progress in the resolution achieved has always been related to the introduction of new image processing methods and to improvements in understanding of the overall strategy of single particle analysis. The new techniques either were adopted from methods developed in other fields, or were specifically designed to deal with extremely low Signal-to-Noise Ratio (SNR) data in EM. In the former category we can place multivariate statistical analysis, clustering techniques, correlation techniques, and tomographic methods, in the latter alignment methods, three-dimensional (3D) projection alignment, contrast transfer function (CTF) correction methods, and common-lines based orientational search. In addition, there have been steady improvements of the quality of the data by seeking better electron microscopy conditions (usage of higher microscope voltage and of microscopes equipped with a field emission gun).
Three-Dimensional Structure of Ribosome-Sec61p Translocation Complexes From Mammals
Authors: Ménétret J-F , Morgan D G , Radermacher M , Neuhof A , Rapoport T A , Akey C W 
Published: July 2020

Abstract
Co-translational translocation at the endoplasmic reticulum (ER) plays a critical role in the targeting of both soluble and membrane proteins to their correct intra- and intercellular compartments. We are studying the 3D architecture of the ribosome-Sec61p complex (translocon), with the aim of understanding the physical mechanisms of gating and transport. To this end, we are using single particle electron cryo-microscopy and 3D reconstruction of frozen hydrated channel complexes, to obtain interpretable and biologically relevant maps.
Previously, we have shown that both co- and post-translational translocation utilize a common central channel comprised of a ring-like Sec61p oligomer. Moreover, this channel morphology is shared with the related Sec YE complex from B. subtilus. Mass analysis, volume calculations and ribosome binding experiments suggest a stoichiometry of 3-4 Sec61p heterotrimers per ring. We currently favor 4 copies of the Sec61p complex per channel, as projection maps demonstrate 4 nearly equi-spaced peaks around the central pore.
A Practical Approach to Low Temperature Microscopy and X-Ray Microanalysis
Authors: Echlin Patrick 
Published: July 2020

Abstract
Water is the most abundant and most important molecule in the hydrosphere, outer lithosphere and the biosphere of our planet. It is also the most abundant and energetically the least expensive building block of living material, forms an integral parts of natural inorganic matrices such as soil and is a constituent of many synthetic organic materials such as paints and polymers. Paradoxically, water does not exist naturally, in the pure state. Water, when converted to the solid state, can provide the perfect matrix in which we may observe the structure and study the in situ chemistry of hydrated samples. We will consider the nature of this solid matrix, and its constituent components in a range of sample, and show how it may be formed, manipulated, examined and analysed. In the short amount of time and space available, one can do little more than highlight the main features of the subject.
Cryo Ultramicrotomy of Biological Samples and Polymers
Authors: Gnaegi H 
Published: July 2020

Abstract
Introduction
Cryo Ultramicrotomy gains increasing importance for immunocyto- and immunohisto- chemistry, element analysis, morphological studies and other investigations.
Major advances in immunocyto-chemistry and the sectioning of frozen hydrated specimens have been realized with the appropriate instrumentation and tools (1,2).
In immuno-electron microscopy it has been found that a considerable reduction of structural damage in tissue and cells can be obtained with a modified sectioning and pick-up method using sucrose/methyl cellulose solution (3, 4).
In recent years various scientists have tried to understand cryo sectioning and the problems related to the cry-osectioning process (5, 6, 7, 8).
A promising attempt to eliminate one of the major artefacts in ultramicrotomy, that of compression", was made with the development of the oscillating diamond knife (9).
In polymer research cryo ultramicrotomy is a well established technique.
However, only little information is available about the the cryo sectioning process for the following reasons: Much cryo sectioning is performed in polymer companies.
Cryomicroscopy of Latex and Latex Films
Authors: Shaffer O L , El-Aasser M S 
Published: July 2020

Abstract
Latexes are dispersions of homopolymers and copolymers, usually in water. Uses of these latexes are many such as protective coatings and adhesives. In order to form a continuous film the polymer must have film forming properties such as a low glass transition temperature (Tg). Latexes are being designed such as one polymer in the core of the particle and a shell of another polymer or perhaps a series of shell layers. Microscopy has become a powerful tool in the examination of the morphology of the latex particles. Because of the use of low Tg polymers, sample preparation and examination by electron microscopy at temperatures above the Tg of the polymer causes the particles to become distorted and no longer representative of their true morphology. Low temperature methods therefore have become crucial in the field of latex microscopy.
Identification of Multiple Colloidal Labels of Various Metallic Composition by Means of Electron Energy Loss Spectroscopy
Authors: Meyer DA , Albrecht RM 
Published: July 2020

Abstract
Since it was introduced by Faulk and Taylor in 1971, colloidal gold (cAu) has become the predominant marker used for EM cell labeling. Double labeling, using cAu of two distinct sizes, was pioneered a decade later. However, as interest continues to grow of how the myriad proteins, enzymes, receptors, and other macromolecules function with respect to one another in the cellular environment, this method has proven largely inadequate for high resolution, multiple labeling because each cAu label must be of sufficiently distinct size to prevent size overlap and confusion between different labels. As the particle size increases, so does steric hindrance between different labels competing for binding sites, while the spatial resolution of the labeling and overall labeling efficiency decrease. In order to address these concerns and surmount the limitations of current labeling methodologies, we have developed colloidal particles of uniform size from various metals including Ag, Pt, Pd, Rh, Ru, Ni, and Cu, in addition to Au.
Gold Cluster Compounds are Useful Immunoprobes
Authors: Robinson JM , Takizawa T , Vandré DD 
Published: July 2020

Abstract
Immunocytochemistry generally refers to methods directed toward obtaining information on the in situ distribution of antigens in cells and tissues. Immunocytochemical methods can be applied at either the light or electron microscope levels, or both in concert. The detection of antibody recognition of an antigen (i.e., localization of an antigen) relies upon a reporter system. At the light microscope level, enzymes (e.g., horseradish peroxidase) or fluorochromes are the most widely used reporters in immunocytochemistry. At the electron microscope level, particulate probes (e.g., colloidal gold) are the most widely used reporters. However, enzymes and even fluorochromes can be used at the EM level.
In this abstract, we discuss our use of gold cluster immunoprobes as the reporter system in both light and electron microscope level immuncytochemistry. These gold cluster immunoprobes, are commercially known as NanogoldTM (NG). These probes are very small with a diameter of 1.4-nm.
Application of STEM-EDX Mapping for Characterizing Microstructural Instabilities En 9-12% Chromium Steels With Martensitic-Austenitic Microstructure
Authors: Klotz U E , Solenthaler C , Uggowitzer P J , Speidel M O 
Published: July 2020

Abstract
Materials for high-temperature application, e.g. in gas-turbine compressor discs or steam turbine rotors, are often susceptible to microstructural instabilities during long-term service. Such instabilities reduce the service life due to a deterioration of the mechanical properties. Therefore, it is most important to identify such instabilities, which often take place in sub-micrometer scale. A class of materials widely used in power generating industries are the martensitic 9-12% Cr steels. In the present work STEM-EDX mappings were used to reveal the distribution of alloying elements in 9-12% Cr steels with a martensitic-austenitic microstructure developed recently.
The chemical composition of the material investigated was Fe-10.1Cr-6.2Co-5.2Mn-2.1Ni-1.2Mo-0.47V-0.1 IN (weight-percent). The material was subjected to a two step heat-treatment of normalizing at 1175°C for 1.5h with subsequent quenching and controlled tempering at 600°C for 20h. Due to the high amount of manganese and nickel a duplex microstructure of 30-40vol.% of austenite in a matrix of tempered martensite is formed during tempering.
Microstructure and Microchemistry of Inconel 600 STEAM Generator Tubing
Authors: Perovic V , Perovic A , Weatherly GC , Brennenstuhl AM 
Published: July 2020

Abstract
Inconel 600 is an austenitic Ni-Cr-Fe alloy which is extensively used for tubing in steam generators of pressurized light water reactors (PWR) and CANDU heavy water reactors, because of its excellent mechanical properties and corrosion resistance. However, there have been instances of intergranular stress corrosion cracking of tubes in operating steam generators. The chemistry and the structure of grain boundaries and grain boundary precipitation have emerged as factors of prime importance in understanding stress corrosion cracking and intergranular attack of nickel-base alloys (see e.g. ref. l).
In this study analytical electron microscopy was used to determine the microstructure of grain boundary and matrix precipitates, grain boundary chromium content and dislocation substructure of selected steam generating tubes of CANDU reactors. The results of the in-service materials are compared with as-received material. Two JEOL 2010 STEM instruments were used in this study.
Observation and Mearsurement of Concentration Moments in Rapid Coarsening, Self-Stressed, Au-Ni Thin Plates
Authors: Hyde B , Reynolds WT 
Published: July 2020

Abstract
The focus of our study is to demonstrate experimentally how elastic stress effects diffusion behavior and coarsening kinetics in a two-phase binary alloy. This work, based on the theory of Cahn and Kobayashi, focuses on elastic stresses in a thin plate. For the case of phase separation with lattice misfit between solute-rich and solute-poor phases, the diffusion of solute distorts the host lattice and causes elastic stress in the matrix. If the plate is sufficiently thin, the stress can cause the plate to buckle. The buckling stress biases the direction of diffusion, which increases the bending stress even further. Thus, the diffusion and the buckling stress are coupled; each affects the other. The interplay between the two is easiest to observe in a solution in which the solute and solvent have high misfit.
Characterization of the Phase Evolution of Mosi2 - TiB2 Composites Produced by In-Situ Reactions Using Scanning Electron Microscopy (SEM), Electron Probe Microanalysis (EPMA), and X-Ray Diffraction (XRD)
Authors: Dempere L A , Kaufman M J 
Published: July 2020

Abstract
Intermetallics are playing an important role in the development of new materials able of sustaining the escalating demands of the aerospace industry. A significant improvement in weight, operating temperatures or mechanical performance is required for materials to be considered as replacements in the most demanding applications. Molybdenum disilicide is one such compound that has potential for high temperature applications. Its most attractive properties are its high melting point (2020°C), reasonable density (6.24 g/cm3), and excellent high temperature oxidation and corrosion resistance. However, low ambient fracture toughness and loss of strength at elevated temperatures have been the most significant limitations to the use of MoSi2 in structural applications.
The more promising solutions for improving the mechanical properties of brittle intermetallics such as MoSi2 are based on the incorporation and control of secondary phases. To date, the artificial introduction of reinforcing phases or their generation via in-situ reactions have been explored.
Copper Oxidation Via “Ex-Situ” TEM
Authors: Kliewer CE , Disko MM , Soled SL , DeMartin G , Baumgartner J , Miseo S 
Published: July 2020

Abstract
The ability to understand and control the microstructure of materials under “real life” conditions is of great interest to both the scientific and industrial communities. In recent years, a variety of “ex-situ” TEM methods have been developed to improve this knowledge base.
ExxonMobil's dedicated reactor system developed for “ex-situ” TEM was used to study the oxidation and reduction of copper on a carbon film and Cu on a Si support. By following the oxidation of specific Cu particles, it was possible to illustrate the oxidation process. A standard, commercially available, 200 mesh Cu grid covered with a holey C support film was used for the Cu on C study. Small Cu islands were vapor deposited from the grid onto the C film during a high temperature reduction in the reactor (Figure 1). The grid was transferred under inert conditions into the TEM where the Cu metal islands were imaged (Figure 2a).
Electron Irradiation Damage in Multi-Component Glasses
Authors: Jiang N , Silcox J 
Published: July 2020

Abstract
Understanding electron beam induced damage in glasses, especially in multi-component glasses, is very important, since the interaction of electron probes with glass is a very common approach to determine glass composition and structure. For example, the decay of characteristic X-ray and Auger electron intensities, using electron beams as probes, of alkalis in glasses have been known for years. In addition, both phase separation and formation of gas bubbles in the glasses have also been reported. Many irradiation effects are strongly dependent on the structure, bonding and composition of matter. In general, three types of mechanisms, knock-on damage, ionization and field-induced migration have been introduced to describe the damage induced by electron irradiation. Here, we demonstrate electron irradiation induced phase decomposition in a multi-component oxide glass, and introduce a modified model to interpret the damage process.
HREM and Image Simulation of Short-Range-Order Domains in Ion Irradiated Zirconolite
Authors: Wang S X , Wang L M , Ewing R C 
Published: July 2020

Abstract
Zirconolite (CaZrTi2O7) is an important phase proposed for immobilization of plutonium. Radiation effects in zirconolite were studied by 1 MeV Kr+ and 1.5 MeV Xe+ irradiation at various temperatures. Zirconolite became amorphous at temperatures below a critical temperature, Tc. The critical temperature was found to be a function of ion species: Tc - 654 K for 1 MeV Kr+ and 710 K for 1.5 MeV Xe+. The temperature dependence of amorphization dose is shown in FIG. 1. Above Tc, the specimen remained crystalline after prolonged irradiation (up to 3.6×l015 ions/cm2). However, the high-temperature irradiated zirconolite was transformed into the fluorite structure (as shown by the strong diffraction maxima in FIG. 2). In addition to the maxima from the fluorite structure, strong diffuse maxima were observed surrounding the Bragg position of pyrochlore superlattice (FIG. 2).
TEM Characterization of Grain Boundary Structure in YBCO Coated Conductors
Authors: Kung H , Hirth JP , Foltyn SR , Arendt PN , Jia QX , Maley MP 
Published: July 2020

Abstract
Studies of defects, such as grain boundaries, in high temperature superconductors (HTS) are important due to the interaction of the defects with flux-bearing vortices. The benefit of in-plane grain alignment has been documented in YBCO thin film bicrystals, in which the high critical current density (Jc) observed across small angle grain boundaries deteriorates exponentially with grain boundary angles beyond ∼ 7°. In addition to the weak coupling effect, a grain boundary may also influence the transport properties via the grain boundary dislocations (GBDs) serving as pinning centers to increase the critical current density. There have been a number of studies on grain boundary structures in YBCO. Despite many differences in structure among the different types of boundaries, it has been established that the low angle [001] tilt boundary in YBCO consists of aperiodic array of edge type GBDs with [100] type Burgers vector that accommodate the lattice mismatch, and the regions between the GBDs are channels of relatively undisturbed lattices [1].