bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electron microscopy of Ni-Ti alloys for medical devices
Authors: Smith Gary A. , Hanke Larry D. 
Published: June 2020

Nickel-titanium alloys (Ni-Ti) have many unique properties that make these alloys excellent prospects for a wide range of applications in medical devices. However, these desirable mechanical properties cannot by utilized for many medical devices if the alloys cause undesirable reactions in the body or corrode from contact with body fluids or tissue.The chemical inertness of Ni-Ti alloys is dependent on a passive film formed on the metal surface. Manufacturing processes, sterilization procedures, and general handling of the devices can have significant effects on the surface condition, and therefore, the corrosion and biocompatible behavior of Ni-Ti alloys.An understanding of the passivation of Ni-Ti alloys, including the effects of mechanical processes, heat treating, and chemical surface alterations, is critical to ensure the benign presence medical devices in the human body.
Nucleation and growth of Si quantum nanocrystals in silicon-rich oxide films
Authors: Mehta S. C. , Smith D. A. , Libera M. R. , Ott J. , Tompa G. , Forsythe E. 
Published: June 2020

The observation of photoluminescence and electroluminescence in Si nanocrystals has generated renewed interest in these novel silicon based materials for their possible application as light emitters and detectors. Silicon Rich Oxide (SRO) films with a uniform dispersion of silicon nanocrystallites in a wider bandgap SiO2 matrix manifest electroluminescence and photoluminescence in the infrared and visible portions of the spectrum. Understanding the nucleation and growth kinetics of these crystallites in amorphous matrix is of critical importance in the fabrication of future optoelectronic devices. One route to the fabrication of Si nanocrystals is by the crystallization of amorphous SiO2-x. Consider the case when x=1. The reaction leading to the formation of Si crystallites can be written as;(1)The nucleation, growth and coarsening processes of Si nanocrystals each require bulk diffusion of Si atoms through the amorphous matrix.
TEM study of CdS nanocrystals formed in SiO2 by ion implantation
Authors: Zhu Jane G. , White C. W. , Budai J. D. , Withrow S. P. 
Published: June 2020

Quantum confinement effects and enhanced optical nonlinearity are expected from II-VI semiconductor nanocrystals, which are important for novel opto-electronic device applications. The ion implantation method has been used in our study to form CdS nanocrystals inside amorphous SiO2. The CdS nanocrystals were studied by transmission electron microscopy (TEM).The samples were implanted (at room temperature) with equal doses (1×1017 ions/cm2) of Cd and S into a SiO2 layer on (100) silicon substrates and then annealed under Ar + 4%H2 ambient at 800°C and 1000°C for 1 h. Implant energies were chosen to overlap the Cd and S ion profiles in the middle of the oxide layer. CdS precipitates are formed during the thermal annealing.The effect of annealing temperatures on the nanocrystals size distributions are revealed in Figs. 1 and 2. The sizes of CdS nanocrystals are in the range of 2 - 11 nm for the sample annealed at 800°C, and in the range of a few to 16 nm for the sample annealed at 1000°C.
Raman imaging in the real world
Authors: Morris Michael D. , Christensen Kenneth A. , Bradley Nancy L. 
Published: June 2020

Recent technological advances including high spectral resolution liquid-crystal tunable filters and high-transmission well-corrected imaging spectrographs have made Raman microscopy a practical technique for study of real-world chemical systems. With modem multivariate signal processing techniques, such as image reconstruction and principal components analysis (PCA) detailed information can be obtained from sets of relatively noisy images or spectra. In this talk we discuss techniques and results in two areas of materials chemistry: crystallization and freeze-drying mechanisms of alkali phosphates and strengthening mechanisms of glasses employed in dental restoration.We employ Raman microspectroscopy to elucidate the structure of aqueous phosphates in solutions ranging in concentration from dilute to supersaturated. PCA of the concentration-dependent spectra of dihydrogen phosphate solutions unambiguously demonstrates the presence of at least three species, monomer, dimer and trimer or short polymer (Figure 1). PCA resolves long-standing disputes over the number and relative concentration of dihydrogen phosphate species PCA can to identify the spectrally unresolved solution species near the surface of a growing dihydrogen phosphate crystal.
FTIR analysis of printed-circuit board residue
Authors: Myers Sharon A. , Cognata Troy D. , Gotts Hugh 
Published: June 2020

Logic boards were failing at Enhanced Mac Minus One (EMMO) test or Integrated Circuit Test (ICT) after printed circuit board (PCB) rework. The failure to boot was originally traced to a suspected bad microcontroller chip. Replacing this chip, or an oscillator tied to the microcontroller circuit, did not consistently solve the boot problem. With further testing, it was found the microcontroller circuit was very sensitive to resistance and was essentially shorted.A resistor in the microcontroller circuit was identified on the flip side of the PCB. Several areas on the board, including the resistor R161, were seen to have a slight white haze/ low gloss appearance on the surface of the PCB. To test if the residue was electrically conductive, five boards were selected whose sole failure was R161. The resistance of the individual resistors was measured with a digital multimeter (DMM). The resistor was then cleaned with isopropyl alcohol and a cotton swab. Each board was retested at ICT and the individual resistors measured again with a DMM. Cleaning the area surrounding the resistor with isopropyl alcohol, corrected the failure four of the times.
Two-Photon Excitation Microscopy in Cellular Biophysics
Authors: Piston David W. 
Published: June 2020

Two-photon excitation microscopy (TPEM) provides attractive advantages over confocal microscopy for three-dimensionally resolved fluorescence imaging and photochemistry. Two-photon excitation arises from the simultaneous absorption of two photons in a single quantitized event whose probability is proportional to the square of the instantaneous intensity. For example, two red photons can cause the transition to an excited electronic state normally reached by absorption in the ultraviolet. In practice, two-photon excitation is made possible by the very high local instantaneous intensity provided by a combination of diffraction-limited focusing of a single laser beam in the microscope and the temporal concentration of 100 femtosecond pulses generated by a mode-locked laser. Resultant peak excitation intensities are 106 times greater than the CW intensities used in confocal microscopy, but the pulse duty cycle of 10 5 limits the average input power to less than 10 mW, only slightly greater than the power normally used in confocal microscopy.Three properties TPEM give this method a tremendous advantage over conventional optical sectioning microscopies for the study of thick samples: 1) The excitation is limited to the focal volume because of the intensity-squared dependence of the two-photon absorption. This inherent localization provides three-dimensional resolution and eliminates background equivalent to an ideal confocal microscope without requiring a confocal spatial filter, whose absence enhances fluorescence collection efficiency. Confinement of excitation to the focal volume also minimizes photobleaching and photo damage - the ultimate limiting factors in fluorescence microscopy of living cells and tissues. 2) The two-photon technique allows imaging of UV fluorophores with conventional visible light optics in both the scanning and imaging systems, because both the red excitation light (~700 nm) and the blue fluorescence (>400 nm) are within the visible spectrum. 3) Red or infrared light is far less damaging to most living cells and tissues than bluer light because fewer biological molecules absorb at the higher wavelengths. Longer wavelength excitation also reduces scattering of the incident light by the specimen, thus allowing more of the input power to reach the focal plane. This relative transparency of biological specimens to 700 nm light permits deeper sectioning, since both absorbance and scattering are reduced.
Correlative Microscopy in Pathology
Authors: Howell D. N. , Miller S. E. , LeFurgey E.A. , Ingram P. , Shelburne J.D. 
Published: June 2020

Microscopy has always provided important anatomical and structural information for biologists and clinicians. The amount of information available has increased exponentially as a result of recent advances in light microscopy, immunohistochemistry, in situ hybridization, electron microscopy, and microprobe analysis. These techniques provide important insights regarding the anatomic distribution, biochemistry, and physiology of a wide range of analytes, including ions and elements, genes and their products, molecular fragments, whole molecules, and macromolecular complexes such as ribosomes and viruses.Proper interpretation of this vast array of new information requires a correlative approach with regard to both different types of data (e.g., biochemical and structural observations) and different levels of resolution (e.g., gross, light microscopic, and electron microscopic observations). This principle is of particular importance to the pathologist, whose ultimate goal is to apply studies of tissues and body fluids to the understanding of disease as it affects the whole organism. Correlative information is particularly important in the interpretation of ultrastructural studies, where high resolution is often obtained at the expense of context. Accordingly, our laboratories have always emphasized the importance of correlative microscopy. In the case of electron microprobe analysis, we have published different regimens that allow the precise correlation of the chemical data obtained with an x-ray spectrometer with structural data seen by transmitted light microscopy (1,2).
Grain Boundary Dislocation Structure and Motion in an Aluminum Σ=3 Bicrystal
Authors: Medlin D. L. , Foiles S.M. , Carter C. Barry 
Published: June 2020

A lattice dislocation may interact with a grain boundary leaving either a residual dislocation or a step or both. These products may then contribute to further deformation by themselves moving along the interfaces. For instance, Pond1 observed the dissociation of a perfect lattice dislocation in an aluminum Σ=3 (211) incoherent twin boundary by a reaction of the type:Furthermore, the a/3[111] dislocation was observed to dissociate into two partial grain boundary dislocations (GBD), with Burgers vectors of approximately 2a/9[111] and a/9[111], separating structurally degenerate regions of opposite rigid body displacement.
Grain-Boundary Characteristics in Austenitic Steel
Authors: Caul M.D. , Randle V. 
Published: June 2020

Grain boundaries are an active area of research interest due to their effect on material property and structure relationships. In order to discuss material properties with regard to grain boundaries it is necessary to know the boundary type. The optimum technique for performing this task is Electron Backscatter Diflfraction (EBSD) in concert with the Scanning Electron Microscope (SEM). By collecting texture measurements in the form of individual orientations from grains it is possible to obtain misorientation measurements from grain boundaries. These measurements are three of the five degrees of freedom necessary to geometrically describe a grain boundary. The other two can be obtained by a serial sectioning technique.Grain boundaries in austenitic steel specimens, isothermally aged at either 700°C or 800°C, have been evaluated with the aim of relating boundary geometry to Cr2N precipitate formation. Samples were analysed using SEM and EBSD in order to obtain orientation measurements of individual grains to misorientations at grain boundaries and to Cr2N precipitates. These precipitates are detrimental to room temperature properties of high nitrogen stainless steels, so a reduction in their formation at grain boundaries would be advantageous. The steel is therefore an ideal candidate material for relating boundaries to material properties. The 700°C isothermally aged sample induces precipitate formation at grain boundaries whereas precipitation by cellular decomposition of austenite occurs in the 800 CC sample. The 700°C sample was used to categorise boundary types using the CSL model and relate this to Cr2N formation. The 800°C sample was used to examine the effect of aging temperature on boundary inclination. Therefore all five degrees of freedom in grain boundary geometry were obtained.
On the Relationship Between Grain-Boundary Character Distribution and Intergranular Corrosion
Authors: Lehockey E.M. , Palumbo G. , Lin P. , Brennenstuhl A. 
Published: June 2020

Intergranular corrosion can under severe conditions lead to “grain-dropping” which results in significant material loss. It has been demonstrated that grain boundaries described by low-Σ CSL misorientations are more resistant to corrosion, cracking (SCC), and sliding (creep) than “general” boundaries, and that the frequency of these “special” boundaries can be enhanced offering the possibility of producing materials with improved bulk corrosion and creep properties. This contribution presents a model for predicting the effect of “special” boundaries on the extent of gross wastage from grain-dropping.For any grain to be ejected from the matrix, all of its bounding interfaces must be fully compromised. Assuming “special” grain boundaries are immune to corrosion and considering a material containing hexagonal prism grains with a diameter and length, d, it can be shown that the probability, X, of observing grain-dropping at a depth, L, through the material thickness is related to the “special” boundary fraction, Fsp, by:
A Simple and Inexpensive Route to Remote Electron Microscopy
Authors: Völkl E. , Allard L.F. , Nolan T.A. , Hill D. , Lehmann M. 
Published: June 2020

Due to the availability of fast computer networks such as Ethernet, FDDI and ATM, the idea of Telemicroscopy, including running electron microscopes from remote locations has gained momentum. Fan, Ellisman, Zaluzec and Parvin, have discussed aspects of systems which support such capabilities. In each of these reports the authors describe new stand-alone software packages that are required to run their systems. In order to make remote microscopy more universally available, we have chosen to expand de facto standard commercial software to provide for computerized microscope control and remote control.All of the major instruments in our user facility have been converted to digital operation and the darkroom has been abandoned completely. It is a logical extension of digital imaging to provide for computer control of the instrument operation, since the instrument parameters can be adjusted using feedback from analysis of the digital image. Digital image recording and display typically uses commercial software such as DigitalMicrograph© (which controls e.g. the CCD camera on the HF-2000). This program
provides the four capabilities necessary to implement instrument control. It allows camera control,provides image processing tools, incorporates a scripting language and also allows C-code to be implemented.
Electron Microscopy and Educational Outreach on the World Wide Web
Authors: Gardner John S. , Rice Judy , Fogt Bill , Erickson Kali , Harrison Russell 
Published: June 2020

For over five years, Utah Valley area high school students have been invited to the Brigham Young University Microscopy Lab to conduct individual and group research projects. This outreach program provides each student with concrete, “hands-on” experience in the field of microscopy and an application of the scientific principles learned in the high school classroom. The program utilizes the expertise of university faculty, lab personnel, undergraduate research assistants, corporate professionals and public school teachers as well as microscopy facilities and equipment (Fig. 1). These elements combine in an effort to mold confident and experienced young professionals. The outreach program has produced students who have published, won contests, earned scholarships and found employment opportunities within the field. However, the program has only been able to serve a limited number of students who want to participate. With the aid of developing technology and the distributed learning model, the influence of electron microscopy can be spread more effectively.The study of microscopy including several related subjects is now more accessible through the creation of a World Wide Web site at Brigham Young University (BYU). Users can select from a variety of menus including a Library, Teaching Center, Learning Center, and Explore Your Mini- Worlds. Student research images have been collected and downloaded through the use of computerized imaging and microscopy (Fig. 2).
The CM120-Biofilter: Digital Imaging of Unstained Specimen, a Comparison of Zero-Loss and Unfiltered Images
Authors: Lücken Uwe , Frank de Jong A. , Busing Wim M. , Rees Jeremy , Nadarzinski Klaus , Kundmann Mike K. 
Published: June 2020

A new system for energy-filtered electron microscopy (EFTEM) has been developed, adapted for the study of life science specimens. Attention has been given to integration, ease of use and the typical problems encountered while investigating unstained and cryo-specimens. Low-dose, cryo-capabilities and a high contrast objective lens have been combined with an imaging energy filter, digital image recording with phosphorus scintillator and advanced image processing capabilities. The CM120-BioFilter is an integration of the CM 120-BioTWIN with the Gatan post-column imaging filter GIF100. The BioTWIN objective lens (Cs=6.2 mm, f=5.9 mm) is optimized for high-contrast imaging. The GIF100 is a computer-controlled, second- order corrected energy filter with a cooled multiscan CCD for digital image recording. Improvement of the contrast can be achieved if inelastically scattered electrons are removed. A comparison of zero-loss filtered and unfiltered images from unstained specimens is presented.The contrast of thick, unstained specimens is limited by the high amount of inelastic scattering. Images from thick sections of unstained spleen tissue shown in Fig. 1 are compared by means of mean and standard deviation of multiscan CCD data.
Detective Quantum Efficiency of 25μm Pixel Imaging Plate
Authors: Taniyama A. , Shindo D. , Oikawa T. , Kersker M. 
Published: June 2020

The 25μm pixel Imaging Plate (IP) is expected to apply to high-resolution transmission electron microscopy (HRTEM) because of its higher spatial resolution than the 50μm pixel IP. It seems that the 25μm pixel IP, which has wide dynamic range and good linearity, is effective for HRTEM with low exposure to reduce electron radiation damage. In order to apply the IP to the HRTEM appropriately, it is necessary to understand the detective efficiency of the IP. In this paper, signal to noise (S/N) ratio and detective quantum efficiency (DQE) of the 25μm pixel IP at accelerating voltages of 100, 200 and 1250kV are presented and a suitable amount of electron exposure for HRTEM is discussed.DQE is expressed as the comparative noise level (σi2/σo2) measured by the ratio of the mean-square fluctuation of incident electrons (σi2) to that of output signal (σo2). In this experiment, the distribution of the incident electrons was assumed to be Poisson statistics.
Automated fine-particle analysis using scanning electron microscopy
Authors: O’Keefe Catherine A. , Watne Tina M. 
Published: June 2020

Owing to analytical advances, submicron particles as small as 0.1 μm can be characterized for chemical composition, size, and shape using scanning electron microscopy (SEM). Once these characteristics are determined, the individual particles can be grouped into categories that provide size, shape, and chemical/mineral distributions of the fine particle fraction.An important application of submicron particle analysis is in solving ash-related problems in coal combustion and gasification systems. The Energy & Environmental Research Center (EERC) at the University of North Dakota is involved in an international consortium formed by the Electric Power Research Institute (EPRI), with U.S. Department of Energy Morgantown Energy Technology Center support, to study ash-related problems associated with the cleaning of hot gases in advanced energy systems. Before the gases are sent through a gas turbine to produce electricity, the particulates are removed with ceramic filters. Filters designed to trap the ash have a tendency to become plugged with ash, eventually causing operational problems. The focus of the project is to characterize the ashes from several filter systems to determine the mechanisms by which difficult-to-clean ash is formed and how it blinds hot-gas filters.
Analysis of completed commercial semiconductors using EPMA
Authors: Packwood R. , Phaneuf M.W. , Weatherall V. , Bassignana I. 
Published: June 2020

The development of specialized analytical instruments such as the SIMS, XPS, ISS etc., all with truly incredible abilities in certain areas, has given rise to the notion that electron probe microanalysis (EPMA) is an old fashioned and rather inadequate technique, and one that is of little or no use in such high technology fields as the semiconductor industry. Whilst it is true that the microprobe does not possess parts-per-billion sensitivity (ppb) or monolayer depth resolution it is also true that many times these extremes of performance are not essential and that a few tens of parts-per-million (ppm) and a few tens of nanometers depth resolution is all that is required. In fact, the microprobe may well be the second choice method for a wide range of analytical problems and even the method of choice for a few.The literature is replete with remarks that suggest the writer is confusing an SEM-EDXS combination with an instrument such as the Cameca SX-50. Even where this confusion does not exist, the literature discusses microprobe detection limits that are seldom stated to be as low as 100 ppm, whereas there are numerous element combinations for which 10-20 ppm is routinely attainable.
Identification of phases in corium held at high temperature in a tungsten crucible by SEM, EPMA, and EBSD
Authors: Schneider B. , Bouchet C. , Perodeaud P. , Dugne O. , Maurizi A. , Valin F. , Guíneau C. , Bordier G 
Published: June 2020

Heat treatments of U − Zr − O mixtures of different oxygen contents (ranging from 1 to 35 at. %) and of a constant U/Zr ratio (U/Zr = 1.35 which is characteristic of the inner part of a pressurized-water reactor) were performed in order to study the high temperature behavior of corium. The selected U-Zr-O mixtures were put in a tungsten crucible and heated to 2050°C. The specimens were thereafter analyzed by Scanning Electron Microscopy (SEM), Electron Probe Micro Analysis (EPMA) and Electron BackScattering Diffraction (EBSD).SEM surface analysis showed a complex system (Fig. 1). Four different phases were characterized. The uranium-rich matrix (noted P1) gave no diffraction pattern by EBSD. The average composition of the sharp grains (P2) located near the tungsten crucible surface was 66 at. % of W and 34 at. % of Zr. The diffraction pattern of this phase was accurately indexed with the fee structure parameters of W2Zr (Fig. 2).