bluuebunny/crossref_metadata_2025_split huggingface dataset:
Micropattern analysis of ZnIn2S4 using AFM and TEM
Authors: Martinez L. , Briceño-Valero J. M. , López-Rivera S. A. , Moore K. , Thorthon J. T. 
Published: June 2020

Semiconductor ZnIn2S4 is the only member of the II-III2-IV4 family with layer structure. The crystal structure of this semiconductor reported by Lappe et. al. is based upon closed packing of sulfur atoms with octahedral and tetrahedral indium atoms and tetrahedral zinc atoms. Previous studies on this material with high resolution transmission electron microscopy and Ramman spectroscopy demonstrate the existence of challenging problems to be resolved related to its intrinsic nature. There is great interest in this material for possible non-linear optical applications. In the present study Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM) have been utilized to reveal crystallographic aspects of this material.Yellowish, plate-shaped, single crystals of ZnIn2S4 were prepared with the chemical transport method using iodine as a transporting agent. Specimens suitable for electron microscope analysis in the growth direction were prepared by peeling off layers with a piece of tape. For AFM analysis, freshly cleaved surfaces were used.
Preparation of successive thin sections of fine oxide particles by an ultramicrotome
Authors: Park G-S. , Shindo D. , Waseda Y. , Yang J-M. , Oikawa T. , Kersker M. 
Published: June 2020

A large number of monodispersed fine oxide particles, which are uniform in shape, size and composition, have been developed as ideal advanced materials. Recently, by the newly developed gel-sol method, various shapes of micron-sized monodispersed hematite particles (α-Fe2O3) were produced, such as peanut-type, ellipsoidal and pseudocubic shapes. To understand the growth mechanism of these particles, it is necessary to investigate their internal structures. In this study, in order to analyze three dimensional internal structure of these particles, we have prepared their successive thin sections with an ultramicrotome and carried out HREM study on these successive thin sections.Monodispersed peanut-type and pseudocubic particles were prepared by the standard procedures of the “gel-sol method. For carrying out ultramicrotomy, these particles were embedded with acrylic resin (methyl methacrylate: n-butyl methacrylate=3:7 or 4:6, benzoyl peroxide 1.5-1.7%) in a gelatin capsule. After trimming with a glass knife, successive thin sections of the particles were obtained by a diamond knife with the optimum slicing condition. The slicing speed and thickness were set to be 0.6 mm/sec and 70 nm, respectively.
Energy-filtered imaging of precipitates in FeCuN alloys
Authors: Rice P.M. , Stoller R.E. , Bentley J. 
Published: June 2020

The microstructures of a series of model ferritic alloys are being characterized by transmission electron microscopy (TEM) techniques. The alloys have varying concentrations of Cu (0 to 0.9 wt%), N (5 to 120 appm), and other solutes to allow a systematic study of the effects of various elements on embrittlement. The first step in this process is the characterization of the alloys in their as-received state: solution treated at 775°C for 17 h, quenched in a salt bath at 450°C for 180 s, and subsequently air cooled.The imaging portion of this initial study is complete; however, several questions about the chemical content of many of the precipitates remain unanswered. The heat treatment described above resulted in extensive precipitation, especially in the high N alloys. It is difficult to distinguish between α” nitride platelets and the ε-carbide platelets which formed in many of the alloys. High-angle tilting is difficult with these ferromagnetic specimens, and the g · R = 0 invisibility criterion previously used for distinguishing the α” nitrides has given ambiguous results.
High-resolution TEM and AEM study in (Au, Tin) thin film on (100) silicon
Authors: Bow J.S. , Hung Y.C. , Kim M.J. , Carpenter R.W. , Kim W.M. , Lee S.K. , Kim S.G. 
Published: June 2020

The cross-sectional microstructure of a (Au, TiN) thin film deposited on a (100) Si substrate without further heat treatment was studied by CTEM, HRTEM, and AEM. HTREM was performed in a Topcon 002B microscope with interpretable resolution limit of 0.18 nm, and high spatial AEM was done in a Philips 400ST field emission gun microscope at 100 kV using a Gatan 666 parallel-detection electron energy loss spectrometer. Cross-section specimens of the interface were prepared by traditional polishing and ion milling. Temperatures used in the whole process of TEM specimen preparation were below 100°C and a liquid-nitrogen-cooled cold stage was used in ion milling to prevent interaction between Au and Si.Ti was co-deposited with Au by sputtering in a nitrogen atmosphere to increase the hardness of the thin Au contact film. Fig. 1a shows the microstructure of the (Au, Ti, N)/Si contact. The features of this microstructure are very similar to the those of pure gold thin films on Si substrates annealed below the Au-Si eutectic temperature (363°C). The thin, white layer was considered to be the original Au/Si interface by Chang et al.
Modification of a TEM for ultra-high-vacuum reflection-EM (UHV-REM) applications
Authors: Hsu Tung , Shih Min-Yi , Latyshev A. V. 
Published: June 2020

A JEOL JEM-100C electron microscope was modified by adding a cryogenic UHV specimen holder for studying clean crystal surfaces with the reflection high energy electron diffraction (RHEED) and REM techniques. The Si(111) (l×l) and (7×7) phase transitions have been successfully observed (Fig. 1). Further modification is in progress for better resolution and other functions. Fig. 2.a shows the unmodified specimen holder and the objective lens of the microscope. The cryogenic holder based on the Novosibirsk design is shown in Fig. 2.b. Liquid nitrogen is continuously pumped through the shell of the holder for achieving UHV inside. The tilt/rotation controls and the current for heating of the specimen are fed through the holder. In this modification, the specimen was not placed at the normal position of the lens and therefore is not at the best position for imaging and diffraction.A new holder is shown in Fig. 2.c. This holder is inserted into the pole piece to place the specimen at the normal position.
Information limit of a 300kV field emission TEM
Authors: Ishikawa I. , Kaneyama K. , Tomita T. , Honda T. , Kersker M. 
Published: June 2020

The use of an FEG on a high resolution microscope will increases the spacial and temporal coherence of the microscope due to the improvement in coherence of the electron source. Additionally, the improved energy spread will extend the envelope of the phase contrast transfer well beyond the first zero point at Sherzer focus. Between the Sherzer point and the ultimate point of zero contrast (the information limit) there is useful information for the analysis of high-resolution images. We have already obtained a resolution of 0.194nm and an information limit of 0.14nm by using the 200kV FETEM (JEM-2010F). In the present experiment, we attempted to obtain a higher resolution and information limit by using the 300kV FE TEM (JEM-3000F).The electron gun is configured with a ZrO/W Shottky emitter which has a small energy spread with a stable emission. The objective lens has a spherical and chromatic aberration of 0.6mm and 1.3mm respectively. The specimen used was gold islands on an amorphous Ge thin film.
Multiple scattering calculations at the oxygen K-edge for SiO2
Authors: Wallis DJ , Brydson R , Gaskell PH 
Published: June 2020

Electron Energy Loss Spectroscopy (EELS) in the STEM is potentially a very powerful technique for studying the structure of materials. The Near Edge Structure (NES) in core loss edges carries information about triplet, and higher order correlation functions and under certain conditions is sensitive to long range atomic correlations. However, since the NES contains strong contributions due to multiple elastic scattering, a simple interpretation in terms of atomic structure is not possible. It is therefore necessary to perform some form of modeling to obtain structural information. One approach to modeling NES is Multiple Scattering (MS) theory.MS calculations have been performed to model the O K-edge ELNES for the α-quartz phase of SiO2 The calculations use a real-space atomic cluster and model the atomic potentials using the Muffin Tin approximation. Effects of the core hole produced upon excitation were accounted for using the (Z+1)* approximation for the excited atom. Energy scales of the calculated data have also been compressed to correct for the energy dependence of the exchange correlation between the photoelectron and the valence electrons which is not accounted for in the calculation.
Development of a multi-user teaching SEM
Authors: Chumbley L. S. , Meyer M. K. , Fredrickson K. , Laabs F. C. 
Published: June 2020

The goal of this project is to develop a next-generation laboratory for the teaching of scanning electron microscopy (SEM). Although SEM is one of the most heavily used analytical techniques in the materials field, it has been extremely difficult to teach because of the single-user nature of SEM instruments up to now. Hence, 20 students in a 3-hour weekly SEM laboratory with one machine can hope to get only 10 minutes of hands-on experience per week. To overcome this problem, we have developed a teaching laboratory that makes use of a local area network to provide a large number of students with direct, interactive access to the microscope. Figure 1 is a photograph of the laboratory in operation. This laboratory was field tested Fall semester, 1994 in three separate classes and the students appear enthusiastic about the new method.The laboratory is based on the JEOL 6100 SEM owned by the Materials Science and Engineering Department. While dated, the microscope does allow a limited number of operational parameters to be controlled through means of an RS-232 serial port by a computer.
Evaluation method for imaging plate resolution by means of phase contrast transfer function
Authors: Oikawa T. , Kosugi H. , Hosokawa F. , Shindo D. , Kersker M. 
Published: June 2020

Evaluation of the resolution of the Imaging Plate (IP) has been attempted by some methods. An evaluation method for IP resolution, which is not influenced by hard X-rays at higher accelerating voltages, was proposed previously by the present authors. This method, however, requires truoblesome experimental preperations partly because specially synthesized hematite was used as a specimen, and partly because a special shape of the specimen was used as a standard image. In this paper, a convenient evaluation method which is not infuenced by the specimen shape and image direction, is newly proposed. In this method, phase contrast images of thin amorphous film are used.Several diffraction rings are obtained by the Fourier transformation of a phase contrast image of thin amorphous film, taken at a large under focus. The rings show the spatial-frequency spectrum corresponding to the phase contrast transfer function (PCTF). The envelope function is obtained by connecting the peak intensities of the rings. The evelope function is offten used for evaluation of the instrument, because the function shows the performance of the electron microscope (EM).
Electron backscatter diffraction a new tool for materials characterization
Authors: Dingley D.J. 
Published: June 2020

Electron backscatter diffraction is an experimental technique that provides the investigator with a tool to determine crystallographic data from sub-micron areas of a polycrystalline sample. The first relevant experiments in elctron backscatter diffraction, were conducted by Venables and co-workers followed later by Dingley and co-workers who developed methods of on-line orientation measurement and later phase identification procedures and methods for internal strain measurement.A specimen is mounted in a scanning electron microscope within which are mounted a phosphor screen positioned vertically and close to the specimen and a low light video camera to view it. The specimen is tilted steeply from the horizontal and oriented to face the phosphor screen. It is normal to enhance the contrast observed in the diffraction pattern using digital background subtraction procedures. A standard arrangement is shown in figure 1.Electron diffraction occurs within the sample as a natural consequence of the scattering of the electron beam beneath the sample surface to form a divergent source of radiation.
Maximum entropy EM tomography: demonstration of improved resolution with adenovirus
Authors: Skoglund Ulf , Öfverstedt Lars-Göran , Burnett Roger , Bricogne Gérard 
Published: June 2020

EMT is a method for three-dimensional (3-D) reconstruction of single objects from electron microscope pictures in a tilt series. The EMT method is general and can be applied to any transparent object, and is not restricted to symmetrical or regularly arranged objects, nor to objects with preferred orientations on a support grid. In its present shape, the EMT method allows reproducible 3-D reconstructions of molecular objects with a resolution in the range of 5 nm. Currently, the EMT method covers the intermediate resolution range where there is no other physical technique available to analyze single molecular complexes.The recent availability of techniques for high quality automatic data collection from vitrified specimens at low dose promises an improvement of the reproducible resolution as well as considerable expansion of the number of users of the EMT technique. A serious drawback of EMT, however, has been the notoriously low quality of single-object 3-D reconstructions when compared to symmetrized reconstructions.
Towards EM tomography of large cellular volumes
Authors: Delaney A. , Bresler Y. , Belmont A.S. 
Published: June 2020

Three-dimensional reconstructions of large cellular subvolumes would be quite valuable in addressing a number of basic questions related to cell ultrastructure. More specifically, we are interested in obtaining reconstructions with several nm resolution over projected areas of 5-50 um diameter and 1-10 um depth. Recently, EM tomography has been combined with serial sectioning as a means of accomplishing this goal. In practice, however, a number of technical problems must still be solved to realize the full potential of this approach, and most applications of EM tomography to date have been limited to high resolution reconstructions over much smaller volumes or lower resolution reconstructions over larger volumes.A major limitation is the limited depth of focus of the electron microscope. Although this depth of focus usually exceeds the section thickness, at very high tilt the range of underfocus through overfocus in the image will approach the diameter of the reconstructed area.
Same-cell correlative video light microscopy/Electron Microscopy tomography: An approach to understanding kinetochore behavior during mitosis
Authors: McEwen B.F. , Osorio G. , Cole R. , Rieder C.L. 
Published: June 2020

The goal of structural biology is to determine structure, structural relationships, and changes in these parameters in an effort to comprehend mechanism of function. In this context same-cell correlative LM/EM provides a powerful approach for elucidating the mechanisms responsible for the behavior of cell components. In this method the event of interest is followed in vivo by video-LM, and the cell then fixed at a critical time during the observational period for a subsequent 3D EM analysis. In this manner the history of a particular event or response can be correlated with the 3D ultrastructure underlying the event.Biologists have long sought to elucidate the mechanism(s) that generate, control and coordinate the poleward and away-from-pole motion of sister kinetochores on each chromosome during mitosis. These “congression” movements require the association of microtubules with each kinetochore (kMTs), and ultimately align the chromosome on the spindle equator. Motion in each direction is distinct because the slow growing (−) ends of kMTs end near the spindle pole while the rapidly growing (+) ends terminate in the kinetochore plate.
Histochemical aspects of nucleic acid detection
Authors: Hamkalo B. A. , Unger Elizabeth R. 
Published: June 2020

This symposium brings together several approaches for the detection of specific nucleic acid sequences that have potential applications at the histochemical level.Trask et al. report on the use of fluorescence in situ hybridization (FISH) techniques to study the arrangement of DNA sequences in normal and diseaserelated chromosomes. The sites of specific DNA sequences can be fluorescently tagged. Different sequences can be labeled with different fluorochromes so that their arrangement can be studied using fluorescence microscopy. The distances between points on the same or different chromosomes can be determined in a large number of interphase nuclei or metaphase chromosomes. A variety of probe types, ranging from single-copy sequences to highly repeated sequences can be employed.Hamkalo and co-workers have used non-radioactive methods at the EM level for the detection of nucleic acid sequences by in situ hybridization. Analysis of metaphase chromosomes by electron microscopy allows for high resolution mapping of chromosomes. A variety of labelling procedures have been employed to illustrate the utility of high resolution nucleic acid sequence mapping in these preparations.
Membrane microdomains: lessons from microscopy
Authors: Robinson J.M. , Oliver J.M 
Published: June 2020

Specialized regions of plasma membranes displaying lateral heterogeneity are the focus of this Symposium. Specialized membrane domains are known for certain cell types such as differentiated epithelial cells where lateral heterogeneity in lipids and proteins exists between the apical and basolateral portions of the plasma membrane. Lateral heterogeneity and the presence of microdomains in membranes that are uniform in appearance have been more difficult to establish. Nonetheless a number of studies have provided evidence for membrane microdomains and indicated a functional importance for these structures.This symposium will focus on the use of various imaging modalities and related approaches to define membrane microdomains in a number of cell types. The importance of existing as well as emerging imaging technologies for use in the elucidation of membrane microdomains will be highlighted. The organization of membrane microdomains in terms of dimensions and spatial distribution is of considerable interest and will be addressed in this Symposium.
Quantifying IgE receptor aggregation from SEM-immunocytology
Authors: Wofsy Carla , Sanders Margaret L. , Donohoe Gregory W. , Pujol Matthew , Oliver Janet M. 
Published: June 2020

Improved procedures for imaging immunogold markers on scanning electron micrographs, new procedures for extracting gold particle coordinates from the images, and both new and standard statistical methods for analyzing spatial point patterns make it possible to study quantitatively the aggregation of cell surface molecules and their localization in specialized membrane domains. The imaging procedures have been described previously. Here we present the methods we have developed or adapted for image processing and for statistical analysis of the immunogold point patterns. We apply the methods to study the aggregation of the high affinity receptor for IgE (Fc∊RI) on rat basophilic leukemia (RBL) cells.The aggregation of cell surface receptors is a necessary step in most known receptor-mediated cellular processes. For example, activation of the intrinsic kinase activity of growth factor receptors requires receptor aggregation, as does the initiation of a variety of antigen-induced responses in the immune system. In the most common form of allergic reaction.
Characteristic feature on structure analyzed by high-resolution electron crystallography
Authors: Fujiyoshi Y. , Mitsuoka K. , Hirai T. , Murata K. , Miyazawa A. , Kimura Y. 
Published: June 2020

The structure of bacteriorhodopsin (bR), which was already analyzed by Henderson et al., is studied by our new electron cryo-microscope equipped with Field Emission Gun (FEG) and Slow Scan CCD camera (SSCCD), because our system together with ice embedding technique enable us to solve the structure of bR at various pH conditions between pH 4.0 and 10.0. Ionization of amino acid is naturally closely related to the translocation of proton and then the function of the proton pump of bR. Therefore, observation of translocation of proton in bR is very important, if possible. Both ice embedding and high resolution techniques are essential to achieve this intention. Therefore, we intended to develop an electron cryo-microscope fit to these techniques and recently we had succeeded it.We collected whole sets of diffraction patterns for bR up to 70 degree tilt at pH 5.5 by using SSCCD, and merged these data of 300 diffraction patterns.
Structure design of osmo-regulated H2O-channel inferred from high-resolution projection map obtained by electron crystallography
Authors: Jap Bing K. , Li Huilin 
Published: June 2020

The aquaporins (AQP) are a class of water channel proteins belonging to the major intrinsic protein (MIP) superfamily. This class of proteins includes the osmo-regulated H20-channel protein AQP-CHJP, which was first identified in erythrocyte membranes and later found to be present in a variety of tissues from organs such as the kidney, gall bladder, lung, intestine and eyes. These channels are believed to be osmotically regulated and to transport water across a number of endothelial and epithelial cell layers during fluid secretion and absorption. AQP-CHJP is extremely specific for the transport of water; small solutes such as urea and ions have been shown to be impermeable to the channels.We have chromatographically purified AQP-CHJP from bovine red blood cell membranes to homogeneity with the use of octylglucoside as the detergent. We have also reconstituted the purified protein with dimyristoyl phosphatidylcholine, yielding crystalline ordered arrays. To increase the percentage of highly coherent crystalline patches, the reconstituted membrane patches were further treated with phospholipase A2 to remove excess lipids.
Low-dose energy-filtered TEM of frozen hydrated virus particles using a post-column energy filter
Authors: Grimm R. , Baumeister W. 
Published: June 2020

Zero-loss filtered imaging of frozen hydrated macromolecular structures has become a commonly applied method over the last ten years, Instruments with in-column filters have been dominant due to their commercial availability (maximum voltage 120 keV), and because they allow the microscope to be used as for standard imaging, with essentially no modification in the procedure for low-dose microscopy Post-column filters have been used mainly in materials science and for intermediate and high voltage microscopes.At the MPI in Martinsried we have recently added a Gatan post-column imaging filter (model 678) to and existing CM 12 electron microscope (120 keV, LaB6 cathode). The lowest magnification of the microscope with the objective lens excited is 600x at the viewing screen (lowered from standard 3000× by free lens control). The imaging filter uses a central portion of about 2 mm diameter of the image or the screen, and adds an additional magnification of 18x.