bluuebunny/crossref_metadata_2025_split huggingface dataset:
Atom Probe Tomography Of Interfaces
Authors: Miller M K 
Published: July 2020

Abstract
The technique of atom probe tomography (APT) enables the x, y, and z coordinates and the elemental identities of the atoms in a small volume to be determined at the atomic level. Therefore, the APT technique may be used to characterize solute segregation to interfaces and precipitation in terms of concentration gradients and precipitate morphology. This type of information may be used to optimize the design of alloys.
The material that was used to illustrate the capabilities of atom probe tomography is a complex polycrystalline nickel-based superalloy, Alloy 718. The composition of this commercial superalloy is Ni- 3.2 at. % Nb, 0.96% Al, 1.15% Ti, 20.3% Fe, 21.8% Cr, 0.26% Co, 1.8% Mo, 0.16% Mn, 0.21% Si and 0.26% C. The material was characterized after a heat treatment oM h at 1038°C + 8 h at 870°C + 500 h at 600°C. Previous atom probe field ion microscopy characterizations of this material has demonstrated that there is no intragranular precipitation after the anneal at 1038°C.
Direct Observation Of Iodine Atomic Chains In I-Doped Carbon Nanotubes
Authors: Fan X , Dickey EC , Pennycook SJ , Grigorian L , Eklund PC , R. BuczkoM  , Pantelides S T 
Published: July 2020

Abstract
Single wall carbon nanotubes (SWNT) were doped with iodine, resulting in charge transfer between the iodine and carbon [1]. It was found that the iodine intercalation is air stable and also reversible by simple heat treatment. This behavior is in contrast to graphite and fullerenes which do not form charge transfer compounds with iodine. Although the iodine-induced charge transfer was not found in any other carbon polymorph solid, it has been found in some low dimensional organic polymers such as polyaniline,[2] forming charged linear-chain polyiodides (I3)- and (I5)-. This suggests that the geometric configuration of the carbon may play a very important role in iodine intercalation. In this study, we use Z-contrast imaging[3] in a VG Microscopes HB603U STEM to directly observe the configuration of iodine within the nanotube bundles. First-principles density-functional calculations are then used to explain the preference for the observed iodine configuration within the nanotubes.
Creep Deformation Microstructures in DS Nb-Hf-Ti-Si In-Situ Composites
Authors: Sitzman SD , Bewlay BP 
Published: July 2020

Abstract
Directionally solidified (DS) in-situ composites based on (Nb) and (Nb) silicides, such as Nb5Si3 and Nb3Si, are presently under investigation as high-temperature structural materials [1, 2]. Alloying additions of elements such as Hf, Ti and Mo to these silicides are also being explored. The present paper describes the microstructure of a DS Nb-silicide based composite before and after creep deformation.
Alloys were prepared from high purity elements (&gt;99.9%) using induction levitation melting in a segmented water-cooled copper crucible. The alloys were directionally solidified using the Czochralski method [2]. Creep tests were conducted at 1200°C to 50% deformation. Characterization was performed using scanning electron microscopy, electron microprobe analysis (EMPA), and electron backscatter diffraction pattern analysis (EBSP).
Orientation Relationships and Constituent Phases
Authors: GUI Jianian , CHEN Xiaomei , LIU Jing , WANG Jianbo , WANG Renhui 
Published: July 2020

Abstract
We report here our preliminary results on orientation determination and phase identification using the electron backscatter diffraction (EBSD) technique. Using a scanning electron microscope (SEM) equipped with the EBSD attachment. it is now possible to study the correspondence and orientation relationships of parent-phase and martensite variants in shape memory alloys (SMAs). Previously, such an information was obtained from large single crystals studied by micro-beam X-ray Laue diffraction and supplemented by transmission electron microscopy study of thin foils. Figs. 1(a), (b) and (c) are three EBSD patterns taken from neighboring areas in a Cu-12.55Al-4.86Ni (wt%) SMA. Computer simulation reveals that Fig. 1(a) belongs to the parent-phase of D03-structure type, and Figs. 1(b) and (c) belong to variants A and D of 2H martensite, respectively. Corresponding simulated EBSD patterns are shown in Figs. 1(d), (e) and (f). Fig. 1 indicates that the (0 0 2)A basal plane of the martensite variant A is transformed from the (-2-2 0)p plane of the parent-phase and its [0-1 0]A direction from the [0 0 1]P direction. The (0 0 2)D basal plane of the martensite variant D is transformed from the (2-2 0)P plane of the parent-phase and its [0 1 0 ]D direction from the [0 0 1]P direction.
3D Reconstructions Using Charge Contrast Imaging
Authors: Baroni Travis C , Griffin Brendan J , Lincoln Frank J 
Published: July 2020

Abstract
Three-dimensional reconstructions are a useful visualisation aid for understanding the volumetric relationships between features in an object. Typically, three dimensional reconstructions have evolved with regards to biological applications, where the collection and manipulation of the data has matured to a point where volumetric rendering has become almost routine. Two common data collection procedures involve either virtual sectioning using CLSM, where layers within the object are imaged successively without mechanical sectioning, or alternatively the projection of the object is imaged, via TEM while being rotated through a range of angles. This paper describes a novel application of three dimensional imaging by collecting 2 dimensional serial section images using a recently described technique for imaging materials using a VPSEM, known as Charge Contrast Imaging.
Figure 1 shows a typical image of a polished grain of gibbsite. Previous work has correlated the appearance of the concentric rings to laboratory controlled precipitation events, thus showing the technique provides information on the precipitation history
What Do We Need to Look Out for When Doing Energy Dispersive Xray Analysis in the Environmental Scanning Electron Microscope?
Authors: Wight Scott 
Published: July 2020

Abstract
The environmental scanning electron microscope (ESEM) is not typically used for quantitative analysis by energy dispersive x-ray spectrometry (EDS) because the electron beam is scattered by the chamber gas forming a broad tail or skirt rather than a focused spot. Scattered electrons can contribute x-rays from areas not directly under the beam, which compromises the spectrum for quantitative analysis. For specimens compatible with high vacuum, quantitative EDS analysis in a conventional electron microscope is preferred. However, the ESEM has found its niche in providing a vehicle for investigating those specimens that for any of a variety of reasons are not suitable for high vacuum electron microscopy and microanalysis. For these specimens, it is important that we find the most accurate way to perform EDS analysis in the low vacuum environment.
Research has focused on reducing, accounting for, predicting, or measuring the electron scattering on a simplified system. Instrumental tricks to reduce the scattering of the primary electron beam have been reported in the past.
Nondestructive Imaging of Pin-Mounted Museum Insect Specimens Using the Field-Emission Environmental Scanning Electron Microscope (ESEM-FEG)
Authors: Robinson Scott , McNeill Billy , Irwin Michael 
Published: July 2020

Abstract
The abilities of researchers to obtain high-quality images and other data from pin-mounted museum insect specimens using conventional scanning electron microscopy (SEM) are hindered by several necessary constraints. The specimens may represent unique exemplars (e.g., holotypes) upon which the taxon name rests. In some cases the specimen may no longer be extant in any environment outside the museum. Thus these insects must always be handled with extreme care,Tegardless of how they are to be observed.
Normal preparation of an insect for SEM involves sputter coating it with a conductive metal to minimize the effects of charging, and conductive paint must be applied to an obscure or uninteresting area to complete the connection to the specimen mount and thus to ground. Generally, unless such specimens have been newly collected, they will have already been killed and allowed to air dry, with a mounting pin inserted through the thorax. The body of the insect shrinks against the pin, which cannot then be removed for observation and later reinserted without damage.
Cationic Peptide Mediated Oligonucleotide Delivery to DU145 Prostate Cancer Cells - Cell Surface Binding Detected by High Resolution SEM
Authors: Karr Joan F , Apkarian Robert P , Petros John A 
Published: July 2020

Abstract
Transfection of mammalian cells can be enhanced by forming complexes between exogenous DNA and cationic peptides which facilitate DNA transport through cell membranes. Although complexes of plasmid DNA and cationic peptides have been characterized by microscopy, little is known about the complexes formed between oligonucleotides (ODN) and cationic peptides or how the ultrastructure of these complexes affects the intracellular delivery via the cell membrane. Because ODN have potential as therapeutic reagents in the treatment of many diseases, there is a need to develop improved methods for effective delivery of these molecules. By analyzing molecular interactions between cationic peptides and ODN and their effects on cell membranes, cell viability, and DNA delivery, improved delivery compounds can be designed. In this paper, we compare the interactions of a 28 base ODN with three cationic peptides: a novel compound, MNLEK (H-Met-(Nle-Lys4)7-Nle-NH2), an established transfection reagent, poly(L-lysine) (∼ 54 kDa), and a recently described cationic peptide which delivers both plasmid DNA and antisense ODN to cells, KALA (WEAKLAKALAKALAKHLAKALAKALKACEA).
For high resolution scanning electron microscopy (HRSEM), DU145 human prostate cancer cells were grown overnight on poly-(D-lysine) coated, UV irradiated silicon chips.
Freeze Substitution of Porcine Heart Valves
Authors: Lightfoot F , Song Y , Taylor M , Brockbank K 
Published: July 2020

Abstract
Freeze Substitution has historically been used for processing small pieces of tissue for microscopic examination. These small pieces of tissue have usually been ultra-rapidly frozen by either metal mirror, high pressure or immersion fixation. In today's expanding field of cryobiology, freeze substitution is being employed to better understand the effects of ice formation and possible deformation of cell structure in tissues that have been processed by controlled-rate freezing. This technique is of extreme importance in laboratories focused on developing methods of preservation by freezing tissues, such as heart valves or veins, which are intended, for clinical applications.
Overview: Many laboratories use methods of substitution, which incorporate acetone as the ice dissolution solvent. We have done comparative studies using both acetone and methanol as a substitution media at -80° C and -90° C. Theoretically, either of the two methods should give satisfactory results provided one uses extremely small tissue samples and follows the accepted guidelines for substitution. Since our protocol requires the use of relatively large samples, which are encased in a voluminous amount of media it is obligatory to adhere strictly to a methanol (-90° C) substitution regimen to be assured complete substitution has taken place (Table 1). Porcine heart valves were dissected into segments consisting of the aortic wall and leaflet. Segments were exposed to a variety of new cryoprotective agents (CPAs) and placed in the center of a parafilm sleeve with 1.5ml of CPA and cooled at 1° C/min to −80°and stored in the vapor phase of liquid nitrogen. Samples were processed for either routine histological studies or freeze-substituted to obtain profiles of ice formation.
Biological Labeling and Correlative Microscopy
Authors: Robinson JM , Takizawa T 
Published: July 2020

Abstract
A variety of biological labeling techniques has been developed in order to obtain specific chemical and spatial information from cells and tissues. Traditionally theses labeling techniques have been categorized as cytochemistry, immunocytochemistry, and in situ hybridization. Another special category relates to fluorescence analog cytochemistry in which specific fluorescently-labeled molecules become incorporated into the pool of endogenous molecules of the cell. They can thus serve as reporters for analysis of the dynamic properties of the population of molecules of interest. Such molecules are usually introduced into cells by microinjection or expressed within the cell (e.g., green fluorescent protein derivatives).
The past few years have witnessed a renaissance in biological optical microscopy. Many of the advances in the elucidation of cell structure-function relationships made through the use of optical microscopy have relied upon fluorescence labeling technology. These advances notwithstanding there remain experimental situations in cell biology that require the higher spatial resolution afforded by electron microscopy. Combining fluorescence and electron microscopy to study the same structures would be very useful in many experimental situations in cell biology. Such an examination of the same structures with more than one imaging modality can be referred to as correlative or integrated microscopy. The number of such studies is relatively small; this is probably due to technical difficulties encountered by various investigators.
Two-Photon Excitation Imaging of Biofilm
Authors: Gerritsen HC , de Grauw CJ 
Published: July 2020

Abstract
Dental plaque is the biofilm which forms on the surface of teeth, comprising a multitude of bacterial species embedded in microbe- and host-derived polymers. Confocal microscopy (CLSM) studies revealed an open architecture in which palisades of biofilm biomass were shown to be interspersed with water channels of lower density. However, the penetration depth of CLSM in these samples is limited to around 20-40 μm, depending on the density of the samples. Therefore, thick biofilms associated with, for example, fissures in the tooth surface, can not be investigated using this technique. The limited depth penetration of CLSM can be overcome by employing two-photon excitation microscopy (TPEM). Due to the use of the longer wavelength excitation light in TPEM, a two to four fold higher penetration into the sample is obtained than in CLSM, see fig. 1. This, together with the reduced photobleaching of the fluorescent probes, makes TPEM well suited for in-depth imaging studies of strongly scattering samples such as biofilm.
The biofilm nature of plaque allows the development of gradients of key biochemical parameters such as ion concentrations. These gradients may result in extreme conditions at certain sites within the plaque that are often associated with the development of the diseased state. Conditions in the oral cavity are overtly aerobic, and the pH of saliva is near neutral.
Breaking the Resolution Limit of Far Field Optical Microscopy: Imaging Molecular and Cellular Interatction on the Nanometer Scale
Authors: Cragg G , Kwon H S , Dong C Y , So P T C 
Published: July 2020

Abstract
Historically, high-resolution optical microscopy has played a vital role in biomedical research. The resolution of conventional optical microscopy is limited by the diffraction effect to about 200 nm and 500-900 nm in the radial and axial directions, respectively. This modest resolution is a major limitation in using optical microscopy for demanding applications. New techniques such as near field optical microscopy, scanning tunneling microscopy, and atomic force microscopy have been developed to circumvent this problem and have achieved atomic resolution in solid state specimens. Unfortunately, the applications of these new techniques have been difficult in biological systems. First, scanning probe techniques require mechanical interaction with the specimens. The mechanical forces exerted by the probe tip may cause sample deformation. This interaction further degrades the achievable image resolution. Resolutions in the range of 50 to 100 nm are often reported for near field optical systems. Second, scanning probe technique has a relatively low frame rate since the required high precision position control imposes severe bandwidth limitations. Scanning probe techniques are more suitable for studying static sample but often have difficulties in addressing many inherently dynamical phenomena in biology. Third, these are surface imaging techniques and are inherently limited in their ability to investigate the 3-D structures of biological specimens.
X-Ray Mapping with Energy-Dispersive and Wavelength-Dispersive X-Ray Spectrometry in the Scanning Electron Microscope: a Tutorial
Authors: Newbury Dale E , Bright David S 
Published: July 2020

Abstract
X-ray mapping is one of the most popular modes for displaying information obtained with x-ray spectrometry performed in the scanning electron microscope. This popularity arises from the ready accessibility and apparent simplicity of information presented in a pictorial fashion, especially when used in conjunction with other SEM imaging modes, such as backscattered, secondary, and specimen current electron images. Further, the rise of powerful, inexpensive computer systems capable of image processing and display has given the analyst a dedicated, on-line tool with the capacity and flexibility needed for problem solving. Figure 1 shows a typical example of mapping. Although the interpretation of x-ray images obtained with a modern digital control and recording system would seem to be straightforward and relatively trivial, there are significant pitfalls and limitations that can easily fool the unwary. In Figure 1, within an individual x-ray map, the observer can reasonably judge where the concentration is lower or higher, at least for a group of contiguous pixels. Can such judgments be made among a set of maps of the same region for different elements, or even for the same element from different regions of the same specimen? With current x-ray processing and display systems, the answers are generally no. In fact, problems that can influence interpretation can arise at each stage of x-ray generation/emission, x-ray spectral collection, processing, and display.
EDS and WDS Automation: Past Development and Future Technology
Authors: McCarthy J J , Frief J J 
Published: July 2020

Abstract
Early Development Automation of electron probe analysis began to flourish in the early 1970s spurred on by advances in computer technology and the availability of operating systems and programming languages that the individual researcher could afford to dedicate to a single instrument. By the end of the decade, most researchers and vendors in the microanalysis field had adopted the PDP-11 minicomputer, and languages such as FOCAL, FORTRAN and BASIC that ran on these computers. A good summary of these early efforts was given by Hatfield. The first use of the energy dispersive detector on the electron probe in 1968 added the need to control the acquisition, display and processing of EDS spectra. As a result, the 70’s were also a time when much attention was focussed on development of software for on-line data reduction and analysis. These efforts produced a suite of programs to provide matrix corrections and spectral processing, and automation of WDS data collection. The culmination of these development efforts was first reported in 1977 with the analysis of a lunar whitlockite mineral by simultaneous EDS/WDS measurement. This analysis determined the concentration of 23 elements, 8 by EDS and took a total of 37 minutes for data collection and analysis. In this paper, the authors noted the complementary use of the EDS and WDS (WDS for trace elements and severe peak overlaps, EDS for other elements and rapid qualitative analysis) in their automated instrument, a convention that remains common on the electron probe even today. Toward the end of the decade the analytical accuracy and precision achieved by automated analysis of bulk samples approached the limits of the instrumentation, with the exception of analysis of light element concentrations.
Two Decades of Improvements The explosive growth in digital electronics and microprocessors for data processing and control functions during the 80’s was rapidly applied to electron probe automation. Second and third generation automation systems included direct control of many microscope functions, beam position and imaging conditions. Motor positioning was more precise and far faster. As a result, the data collection and analysis of 23 elements reported in 1977 could be accomplished at least three times faster on a modern instrument.
SEM and EDS Characterization of Titanium Cathodes Before and After Electrolysis in Heavy Water
Authors: Warner J , Dash J 
Published: July 2020

Abstract
A series of experiments were conducted with titanium cathodes and platinum anodes electrolyzed in heavy water-sulfuric acid electrolyte in closed cells. Each of the cathodes in these experiments was cut from the same titanium foil (99.99% Ti). Each cathode underwent a pre-experiment and a post-experiment SEM (ISI-SS40) and EDS (LINK AN10000) analysis. Of the eight experimental cathodes, three showed post-experimental evidence of localized chemical changes. This is consistent with other findings from this lab. Results obtained on one of these cathodes are presented here.
This cathode was electrolyzed for 115 hours at 0.40A (current density about 2A/cm2). The cathode was ultrasonically cleaned in deionized water for five minutes prior to the pre experiment analysis. Fig. 1 shows the smooth surface of the cathode before electrolysis. No other elements besides titanium were found. After electrolysis in 19.4g D2O +l.0g H2SO4 the cathode was removed from the cell and rinsed by gentle agitation in deionized water for several minutes.
Cryogenic Microcalorimeters for High Resolution Energy Dispersive X-Ray Spectrometry
Authors: J.Höhne  , Altmann M , Angloher G , Bühler M , Feilitzsch Fv , Frank T , Hettl P , Hertrich T , Jochum J , Nüßle T , Pfnür S , Schnagl J , Wänninger S 
Published: July 2020

Abstract
Abstract
Cryogenic detectors with excellent energy resolution and low energy threshold far beyond the level of semiconducting detectors open a variety of new. applications in physics including search for Dark Matter in the universe [2], neutrino physics [3], and IR-, UV- and X-ray astrophysics [4, 9]. Interdisciplinary fields where cryogenic detectors have already shown promising results are the detection of biomolecules [5] and X-ray spectroscopy at synchrotron beam lines [6] and in scanning electron microscopes (SEMs) [7]. For both, astrophysical and analytical use, the development of high resolution microcalorimeters based on iridium/gold phase transition thermometers and aluminum tunnel junctions for use in a compact and universal detector system was initiated.
Our cryogenic microcalorimeters consist of an absorber, a temperature sensor and a weak coupling to a heat sink. An X-ray photon interacts with the absorber and raises its temperature. The sensor measures the temperature increase and the system then, mediated by the coupling, relaxes back to its operating temperature.