bluuebunny/crossref_metadata_2025_split huggingface dataset:
X-Ray Microanalysis of Respiratory Epithelial Cells in the Study of Cystic Fibrosis
Authors: Roomans Godfried M. , Sagström Samuel , Ceulemans Joke L.M. , Bijman Jan 
Published: June 2020

One of the most important clinical symptoms associated with cystic fibrosis (CF) is obstructive airway disease and recurrent airway infections. The smaller airways in CF patients are blocked by viscous mucus, and infections are common and difficult to manage. Generally, lung disease is directly or indirectly the cause of death in CF. The viscous mucus in CF is likely to be a result of defective water transport in the respiratory epithelium. Water transport is coupled to chloride secretion, and it is strongly suspected that a defective chloride channel in the apical membrane of the respiratory epithelial cells is the basic error in CF. We therefore studied changes in the intracellular concentration of chloride (and other ions) by x-ray microanalysis of cultured respiratory epithelial cells under a variety of conditions.Tissues were obtained from material excised during polypectomy. The tracheal mucosa was digested with collagenase and the dispersed cells were plated onto Milliporefilters coated with human placental collagen.
Microprobe AES Combined With Scanning RHEED Microscope
Authors: Sakai Y. , Kitamura S. , Buonaquisti A. D. 
Published: June 2020

Surface micro-structure analysis is very important for surface study in material science. Observations of surface atomic steps and reconstructed structures have been made using several techniques: reflection high energy electron microscopy (RHEEM), low energy electron reflection microscopy (LEERM) and low energy electron diffraction microscopy (LEEDM).In the present experiment, observations of surface micro-structures have been made using a scanning type reflection high energy electron diffraction (RHEED) microscopy. This technique has certain advantages of easy combinations with multiple surface analyzing techniques such as scanning electron microscopy (SEM), Auger electron spectroscopy (AES) and electron energy loss spectroscopy (ELS).A schematic diagram of the scanning RHEED microscope combined with the microprobe AES is shown in Fig. 1. RHEED patterns are observed on the fluorescent screen through a viewing port. To observe the micro-structure (scanning RHEED image or dark field image), a particular diffraction spot is selected by means of the other small fluorescent screen with an aperture.
Angular Resolved Electron Spectroscopy with Parallel Recording
Authors: Min Huang , Flora P.S. , Harland C.J. , Venables J.A. 
Published: June 2020

A cylindrical mirror analyser (CMA) has been built with a parallel recording detection system. It is being used for angular resolved electron spectroscopy (ARES) within a SEM. The CMA has been optimised for imaging applications; the inner cylinder contains a magnetically focused and scanned, 30kV, SEM electron-optical column. The CMA has a large inner radius (50.8mm) and a large collection solid angle (Ω > 1sterad). An energy resolution (ΔE/E) of 1-2% has been achieved. The design and performance of the combination SEM/CMA instrument has been described previously and the CMA and detector system has been used for low voltage electron spectroscopy. Here we discuss the use of the CMA for ARES and present some preliminary results.The CMA has been designed for an axis-to-ring focus and uses an annular type detector. This detector consists of a channel-plate/YAG/mirror assembly which is optically coupled to either a photomultiplier for spectroscopy or a TV camera for parallel detection.
Experimental Control of Electron-Irradiation Damage
Authors: Egerton R.F. 
Published: June 2020

The electrons which convey information about a specimen can also cause permanent changes in its structure and/or chemical composition. The extent of such ‘radiation damage’ depends on several experimental parameters over which the microscopist has control:Incident energy. Displacement damage and sputtering (which arise from high-angle elastic scattering) occur only above certain threshold energies. On the other hand, radiolysis (due to inelastic scattering) varies inversely with incident energy, except below lkeV where an observed threshold effect for aromatic compounds has been interpreted in terms of the need for inner-shell ionization.Electron dose. The loss of structure or elemental concentration is usually exponential (Fig.1) and described by a characteristic dose De, although a second process of much larger De is often present.>Dose rate. For organic compounds, the characteristic dose is normally independent of dose rate, although beneficial effects of high rates and short irradiation times have been reported. For alkali halides, an analogous increase in De with dose rate is observed (Fig.2); the rate of decomposition is presumably limited by diffusion of a species whose concentration gradient is independent of the irradiation flux.
Analytical and High-Resolution EM Study of Crystalline Phases formed at Metal-Ceramic Interface
Authors: Merk N. , Tomsia A. P. , Thomas G. 
Published: June 2020

A recent development of new ceramic materials for structural applications involves the joining of ceramic compounds to metals. Due to the wetting problem, an interlayer material (brazing alloy) is generally used to achieve the bonding. The nature of the interfaces between such dissimilar materials is the subject of intensive studies and is of utmost importance to obtain a controlled microstructure at the discontinuities to satisfy the demanding properties for engineering applications . The brazing alloy is generally ductile and hence, does not readily fracture. It must also wett the ceramic with similar thermal expansion coefficient to avoid large stresses at joints. In the present work we study mullite-molybdenum composites using a brazing alloy for the weldment.A scanning electron micrograph from the cross section of the joining sequence studied here is presented in Fig. 1.
Simultaneous Identification of the Bravais Lattice and Glide Planes From Microdiffraction Patterns: Deduction of the Possible Space Groups
Authors: Paul Morniroli Jean , Gantois Michel 
Published: June 2020

Microdiffraction experiments obtained with a small spot size and a nearly parallel electron beam are well-adapted to most specimens and especially to small particles. They are particularly useful when Convergent Beam Electron Diffraction (CBED) patterns do not give the 2D and 3D information required to identify the point and the space groups. They can also be used to start the identification or the determination of a crystal structure. Specific and simplest CBED experiments are later realized to remove left ambiguities.The microdiffraction Zone Axis Patterns (ZAP) are composed of sharp reflections whose high angular resolution helps to appreciate the shifts and the periodicity differences between the Zero (ZOLZ) and First (FOLZ) Order Laue Zones reflection nets. Observations of thin areas at low temperature are recommended in order to produce many well visible FOLZ reflections.It was already indicated that the crystal system and the Laue class are deduced from observation of the whole pattern symmetry of the reflections.
Convergent Beam Electron Diffraction Zone Axis Pattern Map of Zirconium
Authors: Silva E. , Scozia R. 
Published: June 2020

The purpose in obtaining zone axis pattern map (zap map) from a given material is to provide a quick and reliable tool to identify cristaline phases, and crystallographic directions, even in small particles. Bend contours patterns and Kossel lines patterns maps from Zr single crystal in the [0001] direction have been presented previously. In the present communication convergent beam electron diffraction (CBED) zap map of Zr will be shown. CBED patterns were obtained using a Philips microscope model EM300, which was set up to carry out this technique. Convergent objective upper pole piece for STEM and some electronic modifications in the lens circuits were required, furthermore the microscope was carefully cleaned and it was operated at a vacuum eminently good.CBED patterns in the Zr zap map consist of zero layer disks, showing fine details within them which correspond to intersecting set of higher order Laue zone (HOLZ) deficiency lines.
Application of a slow-scan CCD camera in protein electron crystallography at 400 KV
Authors: Brink Jaap , Sherman Michael B. , Chiu Wah 
Published: June 2020

In protein electron crystallography, high resolution amplitudes and phases are required for a 3D reconstruction of a protein in which one can trace the Cα-backbone. Recording of these amplitudes and phases has so far been done on photographic film. In principle they can be obtained with higher fidelity using an electronic device, such as a slow-scan charge-coupled device (CCD) camera. We use a 1024 × 1024 Gatan CCD camera (model 679) attached to a JEOL 4000EX intermediate voltage electron cryo-microscope. The camera has a 20-30 μm thin P43 phosphor scintillator and an extra set of fiber optics, that reduces the number of x-ray pixels in acquired frames. In this abstract, we will focus on several issues related to the CCD camera in obtaining high resolution diffraction patterns and images from thin protein crystals.To obtain electron diffraction patterns with sufficient statistical definition, one needs to use an adequate electron dose. However, at exposures well above 0.25 e/Å2, the pattern will suffer from blooming due to the central beam.
HREM autotuning on crystalline materials
Authors: Pan M. , Krivanek O.L. 
Published: June 2020

Complete autotuning of a high resolution electron microscope has been well established. It performs the following tasks: align the electron beam along the true electron-optical axis of objective lens (autoalignment), correct the astigmatism (autostigmation), and set the defocus to a user defined value (autofocus). It can also characterize the coefficient of 3-fold astigmatism while performing the autoalignment. Based on diffractogram analysis current HREM autotuning algorithm only works on amorphous materials. In reality, however, most of the HREM practice is performed on crystalline materials. Therefore it is highly desirable to extend the current HREM autotuning algorithm to crystalline specimens. In this abstract we report preliminary studies on attempting to analyze diffractograms from a mix of crystalline and amorphous materials.For crystalline specimens observed in most high resolution electron microscopes, except under UHV conditions, there is typically a thin layer of amorphous contamination due to either sample preparation or poor vacuum conditions. This amorphous layer can be easily seen at the edge of a crystalline sample in the microscope.
Quantitative determination of modulation transfer function and detection quantum efficiency for standard and anti-reflection YAG scintillator slow-scan CCD-camera
Authors: Weickenmeier A.L. , Nüchter W. , Mayer J. 
Published: June 2020

Introduction
The modulation transfer function (MTF) of a slow-scan CCD camera (Gatan modell 679 attached to our Zeiss EM 912 Omega) has been determined with high precision for the standard and the new anti-reflection YAG scintillator. It is shown that deconvolution of experimental patterns allows the reconstruction of image details down to pixel size. From the analysis of deconvoluted noise patterns we found that for this camera the detection quantum efficiency (DQE) is 0.6 in the typical working range of 300 to 3000 electrons per pixel and does not depend on the scintillator. A full discussion of this work can be found in.Experiment
To determine the point spread function (PSF) we punched a hole in a sheet film holder which then was partially covered by one or two knife edges (slit). These masks were projected onto the scintillator. About 600 line scans perpendicular to the edge or slit were extracted and averaged to reduce noise (Fig. 1).
Aggregation growth of nanometer-sized BaTiO3 particles
Authors: Chun C. M. , Navrotsky A. , Aksay I. A. 
Published: June 2020

Nanocrystalline BaTiO3 particles are synthesized under hydrothermal conditions by the reaction of nanosized TiO2 colloids with aqueous solutions of Ba(OH)2 at 80°C. A dissolution-precipitation mechanism is proposed for the formation of BaTiOs by this route, because suspended TiO2 nano-particles dissolve into Ba(OH)2 solution, supersaturate the solution phase, and subsequently precipitate BaTiOs particles. The origin of the rough "raspberry-like" BaTiOs particles during growth stages can be explained by one of two mechanisms: (i) the morphological instability at the growth front during continuous growth, or (ii) aggregation of colloidal particles by multiple clustering. Our TEM studies on samples prepared by controlled seeding experiments show that a multiplicity of low or high angle grain boundaries occur during growth, supporting the aggregation growth.In order to separate the nucleation step from the growth step more efficiently, seed BaTiO3 particles were prepared by adding TiO2 colloids (Degussa, P-25) to 2.23 M Ba(OH)2 solution and hydrothermally reacting at 80°C under atmospheric pressure for 48 hours in polyethylene bottles. The resulting seed particles were recovered by centrifugation, rinsed with C02-free deionized water and freeze-dried.
Intergrainular structure and deformation mechanism in nanocrystalline materials
Authors: Ye H.Q. , Ping P.H. , Li D.X. , Huang J.Y. , Wu Y.K. 
Published: June 2020

It is recognized that boundary structure (GB) characterization is essential in order to understand the structure-properties relationship of nanocrystalline (NC). In most cases, NC materials have to suffer deformation during compacting or ball milling techniques, a deep and systematic study on deformation mechanism is also necessary. In this paper, characterization of microstructure in NC materials synthesized by three methods has been presented.1. Ordered and Disordered Regions at GBs of NC Pd
The NC Pd samples were synthesized by the inert gas condensation and in situ compacting technique. The results of X-ray diffraction and HREM observations showed that the average grain size of the NC Pd is about 10 nm. It can be seen that most of the GBs have ordered structure and no 'gas-like' feature has been observed. Some disordered GB regions, such as nanovoid formed during compacting process, are also detected as marked by "V" in Fig.l. The structural modification from the disordered state was found during in situ HREM investigation.
Stabilizing aqueous clay suspensions by AOT vesicular solutions: a cryo-TEM study
Authors: Li Xiangbing 
Published: June 2020

Production, storage, and performance of suspensions of colloidal solid particles depend critically on suspensions stability. Past studies mostly focused on roles of attractive van der waals force and repulsive electrostatic force between particles. In contrast, this paper reports that aqueous suspensions of clay particles of maximum dimension of 5 to 20 nm can be greatly stabilized by adding vesicular solutions of the anionic surfactant Aerosol OT (AOT).How does the interaction between the clay particles, which bear charge, and multiple bilayers of AOT vesicles lead to more stable suspensions? Cryogenic transmission electron microscopy (cryo-TEM) was brought to bear on this question because it can capture the microstructure in fluids without staining or drying artifacts. Cryo-TEM samples were made by rapidly freezing thin liquid films (200-500 nm) in a controlled environment vitrification system (CEVS)5 to preserve the original structures. Clay particles (often hexagonal) were flat plates and tended to associate face-to-face (Fig. la). Cryo-TEM images show that 3 wt% and 5 wt% AOT formed unilamellar and multilamellar vesicles in solutions (Fig. lb-c).
In situ grain growth study in electrodeposited nanocrystalline Nil.2WT.%P alloy
Authors: Smith D. A. , Mehta S. C. , Erb U. 
Published: June 2020

Nanocrystalline (nc) materials, owing to their ultrafine grain sizes, exhibit several physical and mechanical properties which are significantly different from, and in many cases, superior to those of their polycrystalline counterparts and therefore promise their usage in a number of applications. However, very poor resistance of nc pure metals against thermal grain growth severely limits the application of these novel materials. Several attempts are being made to improve the thermal stability of nc materials. The conventional approaches of grain boundary pinning by second phase precipitates and solute drag effects are commonly being employed. However, the kinetics of grain growth and the roles of solute atoms and second phase precipitates in affecting grain growth inhibition in these nanolength scale materials are still not well understood.A transmission electron microscope study has been made of the microstructural evolution of electrodeposited nanocrystalline Ni-1.2wt.%P alloy and pure nickel during heating experiments performed in-situ.
In Situ Atomic Force Microscopy of Pt/Ti film morphology changes on a microelectronic gas sensor operating at elevated temperatures
Authors: DiBattista M. , Patel S. V. , Mansfield J. F. , Gland J. L. , Schwank J. W. 
Published: June 2020

Thin film electronic devices that employ resistance change responses of Pt / Ti films to detect gas species have been microfabricated at the University of Michigan. Atomic force microscopy (AFM) is used to investigate morphology of the Pt / Ti sensing films deposited on the microfabricated device. These Pt / Ti sensing films are strongly influenced by many factors, making it difficult to determine the exact relationship between film structure, chemical sensitivity, and selectivity. In-situ AFM investigations of Pt / Ti films on this device at elevated temperatures provides the opportunity for real time observation of film morphology changes under controlled conditions, testing sensing film stability during device operation, and correlating film structure to resistance.Observation of the Pt / Ti film surface and in-situ resistance measurements at elevated temperatures are possible due to the construction of the sensing device. The sensors are based on chemically active thin films deposited on a micromachined silicon window, supported by a 300 μn thick silicon rim.
Formation of polytype microstructure in pulsed-laser-irradiated sapphire substrates
Authors: Cao Siqi , Pedraza A. J. , Allard L. F. , Lowndes D. H. 
Published: June 2020

Surface modifications of wide-gap materials are produced by pulsed laser irradiation. Under given conditions, these near-surface modifications can promote adhesion enhancement of deposited thin film materials, and activation for electroless deposition. AIN decomposes during laser irradiation leaving a metallic film on the surface. High density dislocations were observed in the surface layer of AIN that was laser melted but not decomposed. The laser melted alumina becomes amorphous at a laser energy density of ~1J/cm2. In sapphire, γ-alumina is formed when the sample is laser irradiated in Ar/4%H2. Here, we report the formation of a new structure in laser-irradiated sapphire.Optically polished c-axis sapphire substrates were laser-irradiated in an Ar/4%H2 atmosphere at 4J/cm2 energy density, using a 308 nm-wavelength laser with a pulse duration of ~40 ns. Sapphire (A12O3) has a space group R 3 c and can be described as an hcp structure having oxygen and aluminum layers alternately stacking along the c-axis.
Lorentz microscopy observation of vortex dynamics due to transport current
Authors: Yoshida T. , Kasai H. , Bonevich J.E. , Matsuda T. , Tonomura A. 
Published: June 2020

At present, Lorentz microscopy is the only one method to visualize individual vortices in superconductors and observe their motion in real time. Using this technique, we have investigated the fascinating vortex dynamics in superconductors, niobium and BSCCO. And recently we applied it to investigate current driven vortex motion.The vortices are driven by the Lorentz force due to the transport current, and begin to move. This couses the vortex to dissipate the energy i.e., causes the resistive state in the superconductor. Therefore to clarify the vortex motion is important especially in the relation with vortex pinning.The sample we examined was niobium thin film, which was single-crystallized by annealing and thinned by chemical etching. It was put in the low temperature specimen stage specially developed for the vortex observation, which was installed in 350 kV FE-TEM based Hitachi H-9000.We observed current driven vortex motion in the temperature (T) range from 4.5 K to Tc = 9.25 K and in a (externally applied) magnetic field (B) up to 100 Gauss.
TEM phase transformation study of (VO)2P2O7 catalyst
Authors: Li Z. G. , Torardi C. C. , Horowitz H. S. 
Published: June 2020

(VO)2P2O7 (VPO) is known to act as a heterogeneous catalyst in the oxidation of n-butane to maleic anhydride. DuPont has developed a new circulating fluid bed process for this reaction, and first commercial plant using this technology is scheduled to start up in early 1996. VPO catalyst is typically formed by transforming the vanadyl hydrogen phosphate precursor (VOHPO4. 1/2H2O) to the vanadyl pyrophosphate active phase. It was the object of the current study to develop a more fundamental understanding of this phase transformation.Transformation conditions were 500° - 700° C in nitrogen. The hydrated precursors used in this study were in the form of plate-shaped single crystals. The crystallographic convention is given in Table 1. Microstructural and morphological changes associated with the phase transformation were studied at scales ranging from the mm to the nm range using scanning electron microscopy (Hitachi S-4000) and transmission electron microscopy (JEM 2000FX). Figure la is an SEM showing the corner of a precursor crystal plate with the c axis indicated.
Analysis of fluidized cracking catalysts by Atomic Force Microscopy
Authors: Gould S.A.C. , Occelli M.L. 
Published: June 2020

In the United States, five million barrels of oil per day or one third of all processed crude oil is catalytically converted with fluidized catalysts, a process which requires 500 tons of catalyst daily. Given these immense quantities, a small percentage difference in the efficiency of the oil conversion to liquid fuel can result in a savings of many millions of barrels of oil annually. In this study we have used a contact mode atomic force microscope (AFM) to study to topography of a set of fluidized cracking catalysts (FCC) from the μm level down to the atomic. We selected this technique because it is believed that the cracking in the FCCs occurs mainly on the catalysts top 10-15 μm suggesting a surface which contains numerous pores, something the AFM can well characterize.We obtained our FCC (GRZ-1) from Davison. The FCC is generated so that it contains and estimated 35% rare earth exchaged zeolite Y, 50% kaolin and 15% binder.
Divergent beam microanalysis studies of bimetallic platinum catalysts supported on γ-AL2O3
Authors: Fryer JR , Huang Z , Stirling D , Webb G. 
Published: June 2020

Platinum dispersed on γ-alumina is used as a reforming catalyst to convert linear hydrocarbons to cyclic aromatic products. To improve selectivity and lifetime of the catalyst, other elements are included, and we have studied the distributions of Pt/Re, and Pt/Sn, bimetallic systems on the support both before and after use in octane reforming. Often, one or both of the components are not resolvable by HREM or microanalysis as individual particles because of small size and lack of contrast on the alumina, and divergent beam microanalysis has been used to establish the presence and relationship between the two elements.In the majority of catalysts the platinum is in the form of small panicles, some of which are large enough to be resolvable in the microscope. The ABT002B microscope with Link windowless Pentafet detector, used in this work, was able to obtain a resolvable signal from particles of 2nm diameter upwards. When the beam was concentrated on to such a particle the signal was at a maximum, and as the beam diameter was diverged - at the same total beam intensity and dead time - the signal decreased as shown in Figure 1.