bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electron microscopy of keratinocytes cultured on a collagen substrate used as an allograft for the treatment of chronic wounds
Authors: Jennings Debby A. , Morykwas Michael J. , Argenta Louis C. 
Published: June 2020

Grafts of cultured allogenic or autogenic keratlnocytes have proven to be an effective treatment of chronic wounds and burns. This study utilized a collagen substrate for keratinocyte and fibroblast attachment. The substrate provided mechanical stability and augmented graft manipulation onto the wound bed. Graft integrity was confirmed by light and transmission electron microscopy.Bovine Type I dermal collagen sheets (100 μm thick) were crosslinked with 254 nm UV light (13.5 Joules/cm2) to improve mechanical properties and reduce degradation. A single cell suspension of third passage neonatal foreskin fibroblasts were plated onto the collagen. Five days later, a single cell suspension of first passage neonatal foreskin keratinocytes were plated on the opposite side of the collagen. The grafts were cultured for one month.The grafts were fixed in phosphate buffered 4% formaldehyde/1% glutaraldehyde for 24 hours. Graft pieces were then washed in 0.13 M phosphate buffer, post-fixed in 1% osmium tetroxide, dehydrated, and embedded in Polybed 812.
Three-dimensional confocal microscopy in living cells: historical development, practical application and limitations
Authors: Masters Barry R. 
Published: June 2020

Confocal microscopy is a rapidly evolving technique which is solving problems in the biological and material sciences. This tutorial focuses on the confocal microscopy of living cells. Both in vivo and in vitro applications of confocal microscopy will be reviewed. Applications of confocal microscopy of the eye will illustrate the concepts. Fluorescence and back scattered confocal microscopy are critically reviewed. A bibliography on confocal microscopy is given to aid the users of this technique.Books (Optical Theory, Image Formation, Fluorescence Techniques)
•Theory and Practice of Scanning Optical Microscopy, (eds. T. Wilson, C. Sheppard), Academic Press, London, 1984.•Confocal Microscopy, (ed. by T. Wilson), Academic Press, London, 1990.•Handbook of Biological Confocal Microscopy, (ed. J.B. Pawley), Plenum Press, New York, 1989.•New Techniques of Optical Microscopy and Microspectroscopy (ed. R.J. Cherry), CRC Press, Inc., Boca Raton, Florida, 1991.•Noninvasive Techniques in Cell Biology, (eds. J.K. Foskett, S. Grinstein), Wiley-Liss, New York, 1990.
SEM/FESEM imaging of lamellar structures in melt extruded polyethylene films
Authors: Chen R.T. , Jamieson M.G. , Callahan R. 
Published: June 2020

“Row lamellar” structures have previously been observed when highly crystalline polymers are melt-extruded and recrystallized under high stress. With annealing to perfect the stacked lamellar superstructure and subsequent stretching in the machine (extrusion) direction, slit-like micropores form between the stacked lamellae. This process has been adopted to produce polymeric membranes on a commercial scale with controlled microporous structures. In order to produce the desired pore morphology, row lamellar structures must be established in the membrane precursors, i.e., as-extruded and annealed polymer films or hollow fibers. Due to the lack of pronounced surface topography, the lamellar structures have typically been investigated by replica-TEM, an indirect and time consuming procedure. Recently, with the availability of high resolution imaging techniques such as scanning tunneling microscopy (STM) and field emission scanning electron microscopy (FESEM), the microporous structures on the membrane surface as well as lamellar structures in the precursors can be directly examined.The materials investigated are Celgard® polyethylene (PE) flat sheet membranes and their film precursors, both as-extruded and annealed, made at different extrusion rates (E.R.).
Errors in holz-line simulations
Authors: Eades J.A. , Moore S. , Pfullmann T. , Hangas John 
Published: June 2020

In the fall 1990 issue of the EMSA Bulletin, one of us launched an appeal, asking to be sent output from programs that simulate HOLZ lines. This unusual request was prompted by the discovery that a number of such programs (including some that are well respected and widely distributed) gave different results. Several people responded and as a result we have been able to establish the reasons for the discrepancies - at least enough of them that we are confident in giving a sample result.All the programs that we have considered are programs that calculate the positions of HOLZ lines in the kinematic approximation. However it is generally assumed that a kinematic simulation will give a result that agrees with the full dynamical theory and with experiment, provided that the kinematic calculation is carried out using an incorrect value of the accelerating voltage. This will be true for lines close enough to the zone axis and provided that a different voltage is used for each Laue zone.
Atomic structure images formed by core loss electrons
Authors: Hashimoto H. , Makita Y. , Nagaoka N. 
Published: June 2020

Energy selected atomic structure images were first recorded with plasma loss spectrum of silicon by Ajika, Hashimoto et.al using a single sector magnetic spectrometer (Gatan 607) in 1985 without any lenses behind the narrow energy selecting slit. The distorted images were compensated by a computer. Krivanek and Ahn used three quadrupole lenses and TV camera behind an energy selecting slit, and were able to cancel the energy dispersion to first order, producing a sharp and undistorted plasma loss image of (110) planes in silicon.In the present paper, the observations were made with a prototype of the Gatan imaging filter, which consists of a single magnetic sector of 10 cm bending radius, a pre-sector focussing and alignment coil assembly, two spectrum-magnifying quadrupoles, a piezoelectrically driven retractable energy-selecting slit, an imaging lens assembly comprising 4 quadrupoles and 5 sextupoles, a retractable TV-rate CCD camera, and a slow-scan CCD camera (Figs.1 and 2).
Energy filtered imaging of nanophase materials
Authors: Ahn C. C. , Hong L. , Eckert J. , Fultz B. , Johnson W. L. 
Published: June 2020

Considerable attention and effort has been devoted to the synthesis and evaluation of nanophase materials (from 4 - 8 nm) because of their measureably altered elastic moduli, heat capacities and magnetic properties from that of larger grain sized material. Because grain boundaries represent such a large volume fraction of the consolidated material, a fundamental understanding of their nature is crucial in developing viable physical models for bulk behavior.One of the difficulties that is encountered in this endeavor is in determining the level of composition variation or contamination at boundaries that may occur during the synthesis process. While gas condensation has produced quantities of materials suitable for x-ray diffraction and TEM analysis, scale up technologies like aerosol reaction and mechanical attrition may introduce impurities which might considerably alter the desired properties. Energy filtered imaging would also be useful for studying enhanced solute solubility or segregation in nanostructured alloy systems produced by ball milling.
Impurity segregation to grain boundaries and defects in AIN
Authors: Callahan D. L. , Kenik E. A. , Alexander K. B. 
Published: June 2020

The technological development of aluminum nitride (A1N) substrates is driven to a large extent towards the economical production of high thermal conductivity sintered ceramics for substrate applications. Stringent demands on matrix purity combined with the practical necessity of sintering additives have led to extensive analyses of property controlling matrix defect structures and of the role of additives in both matrix purification and sintering. Of particular interest are defects such as inversion domain boundaries (IDBs) and grain boundaries which may serve as segregation sites for the dominant impurities in A1N, particularly oxygen. In this work quantitative methods of analytical electron microscopy are applied to the analysis of chemical segregation in electronic grade A1N.Energy dispersive x-ray spectroscopy (EDAX 9100) using a ∼2-nm-diam. probe (Philips EM400T/FEG) has revealed the segregation of yttrium and calcium to the grain boundaries of commercial Toshiba N-170 ceramics. This segregation was extremely localized; examination of the A1N matrix within 4 nm of the boundary revealed no clearly discernable Y or Ca and no contributing phase, either crystalline or amorphous, was distinguished by microdiffraction using the same probe.
Theoretical considerations in lattice resolution high-angle annular dark-field imaging
Authors: Amali Adam , Rez Peter 
Published: June 2020

The highly coherent probe in the scanning transmission electron microscope(STEM) equipped with a with high angle annular dark field (HAADF) detector has become an important tool for high resolution work in the study of crystals.with potential for providing chemically sensitive information.The results of Pennycook and Boatner and the calculations of Kirkland et al clearly demonstrated that lattice resolution was possible using HAADF imaging.There has been other contributions since then.The theoretical interpretation of these images however remains controversial and other contributions have focussed on whether the imaging is coherent or incoherent.In the present work we analyse the various mechanisms that contribute to the large angle signal obtained in the HAADF detector.Bloch waves are used to describe the elastic dynamical scattering; and in the abscence of any strong Bragg reflections.the amplitude observed in the detector plane in the STEM may be represented by a simple convolution between the scattering function of the object and the probe.
Application of ALCHEMI to Doped YBa2Cu3Ox superconductors
Authors: Wheelert R. , Miller D. J. , Lin C-H. , Eades J.A. 
Published: June 2020

A large number of high temperature superconductors based on cation-doped YBa2Cu3Ox have been reported in the literature. The interest in these materials is due to the great sensitivity of both the structure and superconducting properties to elemental substitutions at each type of atomic site in the crystal lattice. This provides a system where controlled changes in properties can be made which could then lead to an improved understanding of the mechanisms of superconductivity.These studies rely on accurate knowledge of dopant site location within the unit cell. Hence, ALCHEMI, which has been successfully carried out in other complex systems, has potential applications for these materials. The work reported here demonstrates the viability of the technique for providing very basic information on site selectivity in the complex perovskite structure of YBCO. Three samples have been evaluated: an electropolished YBCO single crystal, a crushed single crystal having Sr substituted for Ba and a crushed ceramic material with Co substituted for Cu.
Energy loss composition analysis of CVD silicon oxide layers
Authors: Waytena G 
Published: June 2020

The potential application of Plasma Enhanced Chemical Vapour Deposition (PECVD) oxides as gate, storage mode, or isolation dielectrics in Very Large Scale Integration (VLSI) technology, and as gate dielectrics in compound semiconductors or thin film transistor devices has been documented. There is considerable evidence that the composition is not uniform in oxides grown by PECVD. As the oxide layers are very thin computer controlled parallel EELS of cross sectional specimens was used to obtain composition profiles. The films used in this study were deposited on a (100) Si substrate at 300° C under conditions that were believed to result in stoichiometrically correct SiO2 as determined by AES. The layer width was believed to be 70Å, as determined by linear extrapolation of a thickness versus deposition time curve obtained from larger deposition times.Figure 1 shows a cross-section high resolution electron micrographs taken taken along the (110) zone axis at a defocus of-370Å , respectively, from a slightly thick region of the specimen (150-200Å)..
The measurement of inner-shell ionization cross aections by electron impact in a TEM
Authors: Gauvin Raynald , L'Espérance Gilles 
Published: June 2020

Values of cross sections for ionization of inner-shell electrons by electron impact are required for electron probe microanalysis, Auger-electron spectroscopy and electron energy-loss spectroscopy. In this work, the results of the measurement of inner-shell ionization cross-sections by electron impact, Q, in a TEM are presented for the K shell.The measurement of QNi has been performed at 120 KeV in a TEM by measuring the net X-ray intensity of the Kα line of Ni, INi, which is related to QNi by the relation :(1)where i is the total electron dose, (Ω/4π)is the fractional solid angle, ω is the fluorescence yield, α is the relative intensity factor, ε is the Si (Li) detector efficiency, A is the atomic weight, ρ is the sample density, No is Avogadro's number, t' is the distance traveled by the electrons in the specimen which is equal to τ sec θ neglecting beam broadening where τ is the specimen thickness and θ is the angle between the electron beam and the normal of the thin foil and CNi is the weight fraction of Ni.
Secondary electron imaging of atomic layers on silicon surfaces
Authors: Homma Yoshikazu 
Published: June 2020

We earlier reported that the atomic steps on a Si(l11) clean surface can be clearly imaged by scanning electron microscopy (SEM) with a grazing incidence of the primary electron beam. In this paper, atomic step contrast is investigated with respect to the positional effects of the secondary electron (SE) detector. SE-images of the 1×2 and 2×1 domains on Si(100) are presented for the first time.An ultrahigh vacuum SEM equipped with a field emission electron gun (modified Hitachi S-800) is used for surface imaging. The pressure during SEM observation is about l×l0-8 Pa. The sample stage can be tilted from 0° (normal incidence) to 90° (grazing incidence). The SE-detector is placed on one side of the sample, near the tilt axis. The previous study utilized a long working distance of 35 - 40 mm between the objective lens and the sample. In the present study, the sample stage is modified so as to reduce the working distance down to 10 mm. This modification allows us to obtain higher resolution images.
Detector strategies for environmental scanning electron microscopy
Authors: Peters Klaus-Ruediger 
Published: June 2020

Environmental SEM operate at specimen chamber pressures of ∼20 torr (2.7 kPa) allowing stabilization of liquid water at room temperature, working on rugged insulators, and generation of an environmental secondary electron (ESE) signal. All signals available in conventional high vacuum instruments are also utilized in the environmental SEM, including BSE, SE, absorbed current, CL, and X-ray. In addition, the ESEM allows utilization of the flux of charge carriers as information, providing exciting new signal modes not available to BSE imaging or to conventional high vacuum SEM.In the ESEM, at low vacuum, SE electrons are collected with a “gaseous detector”. This detector collects low energy electrons (and ions) with biased wires or plates similar to those used in early high vacuum SEM for SE detection. The detector electrode can be integrated into the first PLA or positioned at any other place resulting in a versatile system that provides a variety of surface information.
Dynamic studies of silicide-mediated crystallization of amorphous silicon
Authors: Hayzelden C. , Batstone J. L. 
Published: June 2020

Epitaxial reordering of amorphous Si(a-Si) on an underlying single-crystal substrate occurs well below the melt temperature by the process of solid phase epitaxial growth (SPEG). Growth of crystalline Si(c-Si) is known to be enhanced by the presence of small amounts of a metallic phase, presumably due to an interaction of the free electrons of the metal with the covalent Si bonds near the growing interface. Ion implantation of Ni was shown to lower the crystallization temperature of an a-Si thin film by approximately 200°C. Using in situ transmission electron microscopy (TEM), precipitates of NiSi2 formed within the a-Si film during annealing, were observed to migrate, leaving a trail of epitaxial c-Si. High resolution TEM revealed an epitaxial NiSi2/Si(l11) interface which was Type A. We discuss here the enhanced nucleation of c-Si and subsequent silicide-mediated SPEG of Ni-implanted a-Si.Thin films of a-Si, 950 Å thick, were deposited onto Si(100) wafers capped with 1000Å of a-SiO2. Ion implantation produced sharply peaked Ni concentrations of 4×l020 and 2×l021 ions cm−3, in the center of the films.
Interface structure of epitaxial TiSi2 on Si(lll)
Authors: Nemanich R. J. , Jeon Hyeongtag , Honeycutt J. W. , Sukow C. A. , Rozgonyi G. A. 
Published: June 2020

Among the transition metal silicides, TiSi2 is considered to be a reasonable choice for VLSI applications because it exhibits low resistivity, high temperature stability and compatibility with current processing steps. Thin film reaction of Ti on Si results in the formation of two different forms of TiSi2 which have been identified as the C49 and the C54 crystal structures. The structures are base centered and face centered orthorhombic, respectively. The C49 phase is metastable (ie. it is not represented in the binary phase diagram), and forms at temperatures of 450 to 600°C. The stable C54 phase forms after high temperature annealing to > 650°C. In this paper the relation of the morphology and interface structures of epitaxial C49 TiSi2 on Si(l11) are described.The TiSi2/Si structures were prepared in a UHV system. The TiSi2 surface morphologies were examined by SEM and plan view TEM, and the interfaces were studied by TEM and HRTEM. The phase identification was obtained from the TEM and with ex situ Raman spectroscopy.
Microstructure of silicon proximity bonded in the presence of interfacial oxide
Authors: Sharma Renu , David Theodore N. , Secco Frank 
Published: June 2020

Wafer bonding is of interest for the bonding of similar and dissimilar materials to create novel structures. Since the first use of the technique for creation of silicon-on-insulator structures, there have been a variety of applications such as the formation of p-n junctions, GaAs/Si, Si/glass, MOSFETs and capacitors. The present study was performed to evaluate interfacial regions of Si-wafers bonded by proximity-adhesion. The microstructure and behavior of the Si-wafers and the interfacial-layers was of interest.The conditions investigated in this study consisted of silicon bonded to silicon possessing hydrophobic surfaces, silicon bonded to silicon in the presence of native-oxide layers, and silicon bonded to silicondioxide/ silicon wafers. The Si-wafers were {100} lightly doped n-type, or {111} and n/n+ (Float-zone/ Czochralski). Cross-section TEM specimens were prepared in the <110> substrate-geometry. These were then analyzed using bright-field, dark-field and weak-beam images under varying conditions of electron-beam tilt. A JEOL JEM 200CX transmission electron microscope was used for analysis, operating at 200 kV.
Ion thinning of integrated circuit transverse specimens for transmission electron microscopy
Authors: Shaapur F. 
Published: June 2020

Non-uniform ion-thinning of heterogenous material structures has constituted a fundamental difficulty in preparation of specimens for transmission electron microscopy (TEM). A variety of corrective procedures have been developed and reported for reducing or eliminating the effect. Some of these techniques are applicable to any non-homogeneous material system and others only to unidirectionalfy heterogeneous samples. Recently, a procedure of the latter type has been developed which is mainly based on a new motion profile for the specimen rotation during ion-milling. This motion profile consists of reversing partial revolutions (RPR) within a fixed sector which is centered around a direction perpendicular to the specimen heterogeneity axis. The ion-milling results obtained through this technique, as studied on a number of thin film cross-sectional TEM (XTEM) specimens, have proved to be superior to those produced via other procedures.XTEM specimens from integrated circuit (IC) devices essentially form a complex unidirectional nonhomogeneous structure. The presence of a variety of mostly lateral features at different levels along the substrate surface (consisting of conductors, semiconductors, and insulators) generally cause non-uniform results if ion-thinned conventionally.
Ab initio structure analysis of copper perbromophthalocyanine
Authors: Tivol W.F. , Turner J.N. , Dorset D.L. 
Published: June 2020

The use of high-energy (1200 kV) electrons has been shown to be advantageous in the ab initio structure analysis from electron diffraction of organic compounds. Dynamical scattering from compounds containing heavy atoms may make such an analysis difficult or impossible with data obtained at conventional voltages. In the case that even high-energy electrons do not produce diffraction intensities sufficiently close to the kinematic values, criteria other than the simple minimization of the R-factor must be used to seek the correct structure solution.Copper perbromophthalocyanine (Cu-BrPTCY) was grown epitaxially from the vapor phase onto a clean KCl crystal face. Electron diffraction patterns were obtained from crystals tilted at 26.5° and oriented so that the electron beam was parallel to the c-axis. The AEI EM7 high-voltage electron microscope was used at a voltage of 1200 kV in diffraction mode with a 10 μm selected area aperture. The data were obtained using a minimal electron dose and recorded on DuPont Lo-dose Mammography film (See Fig. 1). Intensities were measured on a Joyce-Loebl MkIIIC flat bed microdensitometer by integrating under the peaks.
AEM: From microns to atoms
Authors: Cliff Graham , Lorimer Gordon W. 
Published: June 2020

The “Manchester Connection” with analytical electron microscopy (AEM) goes back to 1913 and the work of Moseley which was carried out in the Physics Department of the University of Manchester. It was Moseley who first pointed out that there is a simple relationship between Z, the atomic number of an element, and Ek,the energy of the characteristic K-shell X-ray. This relationship is enshrined in Moseley's Law, Ek = 10.3(Z-1).The origin of the modern bulk microprobe analyzer lies in the Ph.D. project of Castaing. Under the supervision of Guinier, Castaing combined an electron microscope and an X-ray spectrometer and obtained a current of a few nA in an electron beam under a micron in diameter. Although enormous advances were made in instrumentation and quantification in the 1950's and 1960's, the spatial resolution for microprobe analysis remained at about 1 μm3 or a mass of about 10-12g, no matter how small the diameter of the incident electron beam. This limitation arises from the physics of the interaction of a high energy electron beam with a solid sample.