bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Use of Electron Diffraction and High Resolution Imaging to Explain why the Non-Dipolar Molecules of l,3,5-Triamino-2,4,6-Trinitrobenzene Display Strong Powder Second Hamonic Generation Efficiency.
Authors: Voigt-Martin Ingrid G , Li Gao , Yakimanski A 
Published: July 2020

Abstract
The exploration of light for applications in optical integrated devices has received world wide attention during the past decade.Organic compounds are of interest because of their large hyperpolarisabilities β and fast response times as well as offering many diferent types of processing geometry. It has been generally understood in the past that the requirements which must be satisfied by the microscopic system (i.e.the molecule) in order for the macroscopic system (i.e. the crystal ) to display second harmonic generation are the following: (a) the molecule must have a dipole moment μ (b) the molecule must have large components of hyperpolarisability β (c) the molecules must adopt a mutual orientation in the unit cell which avoids centro-symmetry.
In practice, TATB was found to have a very large optical susceptibility,although it did not satisfy conditions (a) and (c). With regard to condition (c), it was suggested that structural defects might explain the appearance of second harmonic generation in a centro-symmetric crystal. For this reason we decided to re-examine the problem using electron microscopy and diffraction.
Coherent of PbTe/MgO Bi-Crystals and its Multislice Simulation
Authors: Tanaka N , Egi M , Kimoto K 
Published: July 2020

Abstract
Atomic structure of hetero-interfaces such as semiconductor/oxide is recently much interested from the viewpoints of the device engineering as well as the interface science. Studies of the interface structures have been performed by transmission electron microscopy (TEM)[1], large-angle convergent beam electron diffraction[2] in the cross-sectional observation mode, and by X-ray diffraction[3], TEM[4] and CBED[5] in the plan-view mode. In the present study we applied a coherent convergent beam electron diffraction (c-CBED) technique to the analysis of the rigid-body shift between vacuum-deposited PbTe and MgO (001) thin crystals in the plan-view mode. The c-CBED technique was originated in nano-diffraction experiments by Cowley[6] and the theoretical analysis by Spence[7]. These results suggested a possibility of direct structure-phase determination from the interference fringes formed at coherent overlaps between the diffraction disks. This technique has been recently revived using TEM on SiC by Vine et al.[8] The present study is the first to be concerned with the analysis of interference fringes in c-CBED patterns from epitaxially grown bi-crystals[9].
Nature of In-Plane Phase Transitions in 2D Crystals of the Mitochondrial Porin, VDAC
Authors: Mannella CA 
Published: July 2020

Abstract
VDAC is a voltage-gated ion and metabolite channel that occurs at high density in the mitochondrial outer membrane. Although VDAC is probably related structurally to bacterial porins, small transmembrane voltages cause it to undergo reversible, partial closures that are not seen with the prokaryotic pores. The “closed” states, which are impermeable to ATP, can be induced by effectors, including a synthetic polyanion. There is evidence that closure involves major rearrangements of the pore structure that are difficult to explain in terms of porin-like β-barrels.
The main source of information about the structure of VDAC is electron microscopy of 2D crystals obtained by phospholipase treatment of outer membranes of fungal mitochondria. The unit cell observed after partial lipid hydrolysis (a = 13.3 nm, b = 11.5 nm, γ = 109°) contains six pores which appear to be structurally equivalent at the resolution of correlation averages of crystals embedded in aurothioglucose or vitreous ice (∼1/1.5 nm−1).
Cluster Analysis of Automated Fine-Particle Analysis Using Scanning Electron Microscopy
Authors: O’Keefe CA , Hurley JP 
Published: July 2020

Abstract
Because of analytical advances, submicron particles as small as 0.2 μm can be characterized for chemical composition, size, and shape using scanning electron microscopy (SEM). Once these characteristics are determined, cluster analysis can be used to group the individual particles into categories based on size, shape, and chemical composition.
Submicron particle analysis is important when characterizing the ash to provide information to help solve ash-related problems in coal combustion and gasification systems. Since a combustion system has an excess of oxygen available, the resulting ash is typically easier to characterize than ash from a gasification system. In a gasification system, the lack of oxygen results in additional categories high in Cl and P.
Adequate dispersion of submicron particles for proper analysis of individual particles is required because of the analysis volume of the SEM beam. Therefore, an aliquot of an aqueous solution with a set sample-to-solvent ratio is drawn while being sonicated. A few drops of solution are placed on a vitreous carbon substrate, allowing for particle dispersion on the surface of a smooth substrate. Next, the particles are analyzed by the fine-particle technique (FPT).
High-Energy-Resolution Microcalorimeter Spectrometer for EDS X-ray Micro Analysis
Authors: Wollman D A , Hilton G C , Irwin K D , Dulcie L L , Newbury Dale E , Martinis John M 
Published: July 2020

Abstract
Si(Li) and Ge Energy Dispersive Spectroscopy (EDS) detectors are commonly used for x-ray microanalysis because they are easy to use, inexpensive to operate, and offer both rapid qualitative evaluation of chemical composition and accurate quantitative analysis. Unfortunately, they are limited by energy resolutions on the order of 100 eV, which is insufficient to resolve many important overlapping x-ray peaks in materials of industrial interest, such as the Si Kα and W Mα peak overlap in WSi2. Although WDS spectrometers with excellent energy resolution (typically 2 eV to 10 eV) can resolve most peak overlaps, qualitative WDS analysis is limited by the need to serially scan over the entire energy range using multiple diffraction crystals. There is a need for a new generation of x-ray spectrometers for microanalysis that combines the excellent energy resolution of WDS spectrometers with the ease of use and the parallel energy detection capability of EDS spectrometers.
We are developing a high-energy-resolution x-ray microcalorimeter spectrometer for use in x-ray microanalysis. Our microcalorimeter spectrometer consists of a superconducting transition-edge microcalorimeter cooled to an operating temperature of 100 mK by a compact adiabatic demagnetization refrigerator mounted on a SEM column, read-out SQUID (Superconducting Quantum Interference Device) electronics followed by pulse-shaping amplifiers and pile-up rejection circuitry, and a multichannel analyzer with real-time computer interface.
Development of Atom Counting Technique by Laser Ionization
Authors: Ichimura S 
Published: July 2020

Abstract
The aim of the present study is to discuss the possibility of “counting atoms” by laser ionization technique, which has been applied to post-ionization in sputtered neutral mass spectrometry. The detection of one H2 molecule was tried under an extremely high vacuum (XHV) condition, since the molecule has a higher ionization energy (15.4 eV) than most of elements and the existence probability of it within laser ionization region is less than one under the condition.
Fig.1 shows schematically the experimental setup. The second harmonics (SH) of a picosecond YAG laser was focused with a spherical lens (f=250 mm) into the center of a home-made XHV chamber (Fig. 1a). The focused laser power density (W) is more than 1013W/cm2 for input pulse energy of 30 mJ, and the saturation of H2 ionization can occur under the condition. The repetition rate of the laser was 10 Hz. The XHV chamber can be evacuated to a minimum pressure of 5×10−11n Pa. To the chamber, either an ion counting detector or an ion imaging detector was attached. The ion counting detector (Fig.1b) is composed of ion collecting electrodes, an electron multiplier (EM), and a pulse counter.
Image Formation from Frozen Hydrated Samples in an Energy-Filter-Microscope
Authors: Angert I , Jahn W , Holmes KC , Schröder RR 
Published: July 2020

Abstract
Understanding the contrast formation mechanism in the EM is one of the prerequisites for artefact-free reconstruction of biological structures from images. We found that the normally used correction of contrast formation applied to zero energy loss filtered images corrupted spatial resolution. Therefore the contribution of contrast formed by inelastic electrons was reconsidered, including partial coherence of inelastically scattered electrons and lens aberrations of the microscope. Based on this, a complete description of the zero-loss contrast transfer function (CTF) is now possible.
We used tobacco mosaic virus (TMV), a biological sample known at atomic resolution, for definition of optimum CTF-parameters to reconstruct defocus series from an EFTEM LEO 912. CTF theory as known so far describes image contrast in the weak phase approximation as a linear sum of amplitude and phase contrast. The contribution of amplitude contrast (ratio of amplitude to phase contrast A/P) was determined to be between 7% and 5 % for unfiltered images and 12-14 % for zero-loss filtered images. However, in a filter microscope we remove electrons from the image, so we expect a higher amplitude contrast than in non-filtered images.
Image Restoration and Characteristics of Slow_Scan CCD Camera and Imaging Plates
Authors: Zuo J M 
Published: July 2020

Abstract
The performance of slow scan CCD (SSC) camera [1,2] and imaging plate (IP) [3] for digital recording is limited by resolution and noise. The SSC camera and IP are two digital detectors currently available for transmission electron microscope (TEM). Imaging plates are re-usable flexible sheets, which are used in the standard cassettes. They are readout digitally with a 25 μm pixel size. Both detectors are linear and have large dynamic range. The SSC is a fixed accessory of TEM, images can be acquired, processed and viewed immediately by the microscope operator. The IP fits into a regular film cassette and is used like film except for the processing method. The image plate records electron image by storing electron energy in the potential well of defect states in a photo-stimulable phosphor. The stored image is read out by scanning a laser probe and detecting the stimulated luminescence in a reader. The SSC uses scintillator to convert electrons to photons and detects photons with CCD through optical couplings. The IP has 3000X3760 pixels. The available SSC for electron microscopy ranges from 512×512 to 2048×2048 pixels.
Progress in Computer Assisted Electron Microscopy
Authors: Pan M , Ishizuka K , Meyer C E , Krivanek O L , Sasakit J , Kimurat Y 
Published: July 2020

Abstract
All the lenses, deflectors and stigmators of contemporary electron microscopes are controlled digitally by an internal computer. Control through RS232 serial interface by an external computer has also become a standard feature. This external control has made so-called computer assisted electron microscopy (CAEM) possible and practical. We are developing a CAEM system with two objectives: (1) to free inexperienced microscopists from technical details of operating an electron microscope, especially transmission electron microscopes (TEM); (2) to assist experienced microscopists to operate their microscopes with higher accuracy and efficiency. The features include automated and/or assisted standard operations in focusing, stigmating, and aligning the microscope, and also sophisticated tuning that requires the evaluation of subtle changes in image features such as aligning the incident electron beam direction in the presence of 3-fold astigmatism in objective lens. CAEM can further assist operators in selecting areas or objects and taking images/diffraction/energy spectrum with all the parameters well controlled and catalogued together, thus not only enabling ease-of-use and high accuracy in operation but also yielding more information on the specimen.
Current State of the Art of Digital Imaging in the SEM
Authors: Mackenzie John M 
Published: July 2020

Abstract
Digital image acquisition in the SEM is poised to take over conventional methods of image recording. Because a majority of researchers use Polaroid film which only records about 1,000 lines of information, the acquisition systems available today are capable of matching and possibly exceeding the resolution of this medium.
Several methods are available to accomplish the acquisition task, and they each have certain benefits and disadvantages. by far the simplest and least expensive is to digitize the video output from the SEM when available. Under some conditions the video output can be digitized directly. The advantage of this method is cost. A single frame video digitizer costs less than $200. The signal, however, is usually very noisy. Because the human eye “sees” at a slower rate than video, we normally are “seeing” a 10-20 frame average. When we choose one frame, the results are too noisy. Fortunately, for under $1,500, digitizers that average frames are available. With multiple frames, the results are often acceptable for some applications.
Is Digital Imaging Ready to Replace Photographic Films ?
Authors: Pan M 
Published: July 2020

Abstract
The new generation of cooled slow-scan CCD cameras (SSC) have demonstrated the superior properties to conventional photographic films in sensitivity, resolution, dynamic range, linearity, and on-line availability. Furthermore the digital imaging capability as offered by SSC cameras facilitates image processing and quantitative analysis. Other advantages of digital imaging include easy archiving, sending images to a remote site via high speed communication network, and carrying out telemicroscopy, etc. Today, many laboratories in electron microscopy have already abandoned the traditional “dark room” and switched to digital imaging. One of the obstacle in replacing photographic films with digital imaging is the fact that current SSC cameras (e.g. 1024 × 1024 pixels) do not have enough pixels as compared with the film. Therefore the resolution is often compromised with the field of view when using CCD cameras.
With computer control of electron microscopes and the use of CCD cameras, we have developed automated “montage” software that can automatically shift and acquire images from a microscope, and automatically perform pixel-to-pixel image alignment to form a montage. The size of the montage is defined by the number of images acquired in both horizontal and vertical directions.
Rapid Manual SEM Analysis and the Greening of Digital Data
Authors: McCord DC , Kennedy SK , Kritikos DG 
Published: July 2020

Abstract
Manual scanning electron microscope (SEM) analysis is historically considered to be slow and tedious resulting in a low volume of data. This is due in large part to the mechanics of moving stage locations and recording image and spectral data. Conversely, high volume data acquired using automated SEM analysis has been associated with the need for complex systems for data management and analysis. In addition, the proliferation of high volume digital microscopy and its attendant “ tonnage” of paper images has lead to the desire for a “green” (filmless and hardcopy-reduced) operation.
There are some classes of projects which are amenable to automated feature analysis - discrete features that are distinct from a background material. However, many projects require operator intervention in order to identify the region or points of interest. Yet, these projects may also require that large data sets be acquired and analyzed for statistical rigor.
Automated Acquisition of Cryo-Electron Microscope Images With Slow-Scan CCD Cameras and Microscope Control
Authors: Pan M , Olsont NH , Bakert TS 
Published: July 2020

Abstract
Recording electron microscope images of frozen-hydrated samples under cryo-conditions is a difficult and challenging task. The inherently low sample contrast makes accurate focusing difficult. Furthermore most frozen-hydrated samples are very beam sensitive so that electron dose on the sample must be kept to the minimum. In recent years, the new generation of cooled slow-scan CCD (SSC) cameras have shown superior properties in sensitivity, resolution, dynamic range, linearity, and more importantly their ability to display images on-line. Computer control of electron microscopes via the standard RS232C serial interface has been greatly facilitated by the use of on-line CCD images. We have developed a software package that allows cryo-electron microscope images to be automatically acquired onto a CCD camera via computer control of the microscope. This fully automated feature allows quality cryo-electron microscope images to be recorded with increased efficiency and enhances the possibility of obtaining three-dimensional reconstructions from images.
Merging of Complementary Structural Techniques
Authors: Stewart PL , Chiu CY , Haley DA 
Published: July 2020

Abstract
Cryo-electron microscopy (cryo-EM) and image reconstruction techniques provide a powerful way to study three-dimensional structures of biological complexes. As the resolution of the resulting three-dimensional reconstructions is typically in the range of 10-35 À, information from other structural techniques is often invaluable in analyzing the biological structure. We present the use of crystallographic coordinates to determine the amplitude of motion of a viral receptor binding site and molecular models to assess the degree of quaternary conformational flexibility within a multimeric protein assembly.
In order to visualize the αv integrin receptor binding site on the surface of human adenovirus (150 MDa), we have reconstructed adenovirus in complex with a Fab fragment from a monoclonal antibody (DAV-1) targeted to this site. The peptide epitope of DAV-1 has been mapped by MALDI mass spectrometry to 9 residues within the penton base protein and includes the integrin binding Arg-Gly-Asp (RGD) residues.
The Use of Data Explorer as a 3-D Reconstruction Tool for Microscopy Data Sets
Authors: P.L Jansma , Landis MA , Hansen LC , Merchant NC , Vickers NJ , Tolbert LP 
Published: July 2020

Abstract
We are using Data Explorer (DX), a general-purpose, interactive visualization program developed by IBM, to perform three-dimensional reconstructions of neural structures from microscopic or optical sections. We use the program on a Silicon Graphics workstation; it also can run on Sun, IBM RS/6000, and Hewlett Packard workstations. DX comprises modular building blocks that the user assembles into data-flow networks for specific uses. Many modules come with the program, but others, written by users (including ourselves), are continually being added and are available at the DX ftp site, http://www.tc.cornell.edu/DXhttp://www.nice.org.uk/page.aspx?o=43210.
Initally, our efforts were aimed at developing methods for isosurface- and volume-rendering of structures visible in three-dimensional stacks of optical sections of insect brains gathered on our Bio-Rad MRC-600 laser scanning confocal microscope. We also wanted to be able to merge two 3-D data sets (collected on two different photomultiplier channels) and to display them at various angles of view.
Twin Image Suppression and Field Inhomogeneity in In-Line Electron Holography.
Authors: Weierstall U , Huang XM , Spence JCH 
Published: July 2020

Abstract
Several methods have been suggested for elliminating the twin image in in-line holography, including Franhofer holography as used in our previous work, integration over focus, integration over wavelength, integration over lateral source position and recursion methods such as Gerchberg-Saxton or Fienup (see for all refs.). Fraunhofer holography requires the Fresnel number N =, with d the object size. The integration methods depend on the fact that the real and virtual images have different dependencies on some parameter such as focus, and have proved powerful in photoemission holographic diffraction. Here we apply focus integration and recursion to low voltage, point-projection images of carbon films, and discuss the effects of inhomogeneities in the electric field which arise when the tip is very close to a fibre-shaped sample such as DNA. by embedding biomolecules in solid Xenon at 55K, and using a beam energy of about 9 volts (less than the Xenon bandgap minus the electron affinity), radiation damage to the molecule may be minimized, while the molecule is gently supported by an almost electron transparent medium.
Z-Contrast in a Conventional TEM
Authors: Kirkland EJ 
Published: July 2020

Abstract
Z-contrast produces an image that varies strongly with atomic number and offers limited chemical sensitivity. The annular dark field scanning transmission microscope (ADF-STEM) has recently been used to produce Z-contrast images at high resolution. In a STEM the electron beam is focused into a small probe at the specimen plane and scanned across the specimen. The electrons scattered at high angle are collected by an annular detector to produce a signal that approximately varies as Z11.5 to Z2. The only commercial supplier of dedicated STEM'S (VG-Microscopes, now Thermo) has recently discontinued production, so it is worth considering how to produce an equivalent Z-contrast image in a conventional transmission electron microscope (CTEM).
The reciprocity theorem states that the STEM and CTEM are equivalent if the source and detector are interchanged (reciprocity hold for all orders of elastic scattering so it is not necessary to restrict this discussion to weakly scattering specimens).
Simulation of Magnetic Induction Mapping in the TEM
Authors: Dooley J , De Graef M 
Published: July 2020

Abstract
The design of modern magnetic storage devices with their rapidly increasing information density ne-cessitates a full characterization of the underlying microstructure of the device materials. Lorentz microscopy has for several decades been the main vehicle for micro-magnetic observations. The pri-mary limitation of the Lorentz modes is perhaps the attainable magnification. To avoid saturation, the sample must be placed in a low-field or preferably field-free region in the column, and this invariably means that the microscope can only be operated at low magnifications. Both Fresnel and Foucault images are rather sensitive to the exact experimental conditions which renders quantitative observa-tions quite difficult, if not impossible. Inelastic scattering further limits the usefulness of Lorentz observations to very thin foils.
We have recently reported1 a novel Lorentz microscopy setup, combining a Gatan Imaging Filter (GIF) and a JEOL 4000EX top-entry high resolution TEM, operated at 400 kV with the main objective lens switched off.