Showing papers on "Resolution (electron density) published in 1999"
TL;DR: In this paper, a particle image velocimetry (PIV) system was developed to measure velocity fields with order 1-μm spatial resolution, using 200 nm diameter flow-tracing particles, a pulsed Nd:YAG laser, an inverted epi-fluorescent microscope, and a cooled interline-transfer CCD camera.
Abstract: A particle image velocimetry (PIV) system has been developed to measure velocity fields with order 1-μm spatial resolution. The technique uses 200 nm diameter flow-tracing particles, a pulsed Nd:YAG laser, an inverted epi-fluorescent microscope, and a cooled interline-transfer CCD camera to record high-resolution particle-image fields. The spatial resolution of the PIV technique is limited primarily by the diffraction-limited resolution of the recording optics. The accuracy of the PIV system was demonstrated by measuring the known flow field in a 30 μm×300 μm (nominal dimension) microchannel. The resulting velocity fields have a spatial resolution, defined by the size of the first window of the interrogation spot and out of plane resolution of 13.6 μm× 0.9 μm×1.8 μm, in the streamwise, wall-normal, and out of plane directions, respectively. By overlapping the interrogation spots by 50% to satisfy the Nyquist sampling criterion, a velocity-vector spacing of 450 nm in the wall-normal direction is achieved. These measurements are accurate to within 2% full-scale resolution, and are the highest spatially resolved PIV measurements published to date.
811 citations
19 Jan 1999
TL;DR: In this paper, a diffraction grating was inserted in the illumination beam path at the conjugate object plane (position of the adjustable aperture) and projected through the objective into the object.
Abstract: High spatial frequencies in the illuminating light of microscopes lead to a shift of the object spatial frequencies detectable through the objective lens. If a suitable procedure is found for evaluation of the measured data, a microscopic image with a higher resolution than under flat illumination can be obtained. A simple method for generation of a laterally modulated illumination pattern is discussed here. A specially constructed diffraction grating was inserted in the illumination beam path at the conjugate object plane (position of the adjustable aperture) and projected through the objective into the object. Microscopic beads were imaged with this method and evaluated with an algorithm based on the structure of the Fourier space. The results indicate an improvement of resolution.
641 citations
TL;DR: In this paper, the authors evaluated the prospects for reaching sub-A electron probes through aberration correction in the scanning transmission electron microscope (STEM) and proposed a second generation quadrupole octupole C S corrector that pays particular attention to the influence of instabilities.
552 citations
TL;DR: Experimental verification of sevenfold improved axial resolution has been achieved in three‐dimensional widefield fluorescence microscopy, using a novel interferometric technique in which the sample is observed and/or illuminated from both sides simultaneously using two opposing objective lenses.
Abstract: Sevenfold improved axial resolution has been achieved in three-dimensional widefield fluorescence microscopy, using a novel interferometric technique in which the sample is observed and/or illuminated from both sides simultaneously using two opposing objective lenses. Separate interference effects in the excitation light and the emitted light give access to higher resolution axial information about the sample than can be reached by conventional widefield or confocal microscopes. Here we report the experimental verification of this resolution performance on complex biological samples.
444 citations
TL;DR: These methods are also proving to be useful for locating the selenium atoms or other anomalous scatterers in the multiple wavelength anomalous diffraction phasing of larger proteins at lower resolution.
262 citations
TL;DR: To evaluate the effect of charges on the density map, a difference (|Fo|-|Fc|) map is calculated including data of a resolution lower than 8.0 A resolution, where the charge effect is significant and strong peaks found in the difference map mainly in the backbone region of the transmembrane helices are interpreted.
261 citations
TL;DR: In this paper, the formation and alignment of the scanning transmission electron microscope (STEM) probe using electron Ronchigrams is described, and practical examples of probe formation, Z-contrast imaging and electron energy-loss spectroscopy (EELS) are demonstrated on a Schottky field emission, JEOL JEM-2010F microscope.
225 citations
TL;DR: A computational strategy for structural analyses at this level of detail is described, including a procedure for correcting the contrast transfer function of the electron microscope, which proved instrumental in the analysis of the capsid of hepatitis B virus at 9-A resolution.
173 citations
Patent•
23 Nov 1999TL;DR: In this article, a system constructs a high resolution image from a plurality of low-resolution images where each of the low resolution images includes a plurality-of-colors-of color planes.
Abstract: A system constructs a high resolution image from a plurality of low resolution images where each of the low resolution images includes a plurality of color planes. The system receives the plurality of low resolution images where the plurality of color planes of each of the low resolution images are spatially arranged in at least a partially non-coincident manner. Motion data representative of motion of at least a portion of the low resolution images is determined. The high resolution image is constructed, having a resolution greater than the low resolution images, based upon the non-coincident color planes of the low resolution images, together with the motion data.
159 citations
TL;DR: Automation of data acquisition and data processing, together with the emergence of computational speeds of 10(12) floating point operations per second or higher, will make it possible to extend high-resolution structure determination into the realm of single-particle microscopy, and computational alignment of single particles can begin to replace biochemical crystallization.
149 citations
Journal Article•
TL;DR: In this article, simultaneous acquisition of spatial harmonics (SMASH) has been introduced as a method to acquire magnetic resonance images at increased speeds using a reduced number of phase-encoding gradient steps by extracting spatial information contained in an RF coil array.
TL;DR: It was found that the best effective spatial resolution for aluminium alloys in a tungsten‐filament scanning electron microscope (SEM) was obtained for an intermediate probe current which provided a compromise between pattern quality and specimen interaction volume.
Abstract: Characterization of microstructures containing small grains or low-angle grain boundaries by electron backscattered diffraction (EBSD) is limited by the spatial and angular resolution limits of the technique. It was found that the best effective spatial resolution (60 nm) for aluminium alloys in a tungsten-filament scanning electron microscope (SEM) was obtained for an intermediate probe current which provided a compromise between pattern quality and specimen interaction volume. The same specimens and EBSD equipment when used with a field-emission gun SEM showed an improvement in spatial resolution by a factor of 2–3. For characterizing low-angle boundary microstructures, the precision of determining relative orientations is a limiting factor. It was found that the orientation noise was directly related to the probe current and this was interpreted in terms of the effect of probe current on the quality of the diffraction patterns.
TL;DR: Comparison of the 6 A X-ray map with results of electron crystallography of a paused transcription elongation complex suggests functional roles for two mobile protein domains: the tip of a flexible arm forms a downstream DNA clamp; and a hinged domain may serve as an RNA clamp.
TL;DR: In this article, a new perpendicular thermo-magnetic recording method coupled with magnetic flux detection was developed, and the resolution was substantially improved by flux detection. But this method is not suitable for near-field optics, and it is an effective technique for attaining a higher density beyond the super-paramagnetic limitation.
Abstract: We have developed a new perpendicular thermo-magnetic recording method coupled with magnetic flux detection. The resolution is substantially improved by flux detection. Compared to the latest magneto-optical disk drives, the carrier-to-noise ratio of a reproduced signal is 5 dB higher, and the recording density reaches 8.3 Gbit/inch2. Moreover, this recording method has a good affinity to near-field optics, and it is an effective technique for attaining a higher density beyond the super-paramagnetic limitation in longitudinal magnetic recording.
TL;DR: The results presented are useful in assessing the quality of a protein crystal structure, in selecting structural results to be compared and in evaluating the expected improvement on the solvent structure when increasing the crystallographic resolution.
Abstract: The number of water molecules which are expected to be experimentally located by protein crystallography was determined by multiple regression analysis on a test set of 873 known protein crystal structures determined at room temperature and on another set of 33 structures determined at low temperature. The dependence of the number of water molecules included in the protein models as a function of a number of significant regressors, such as resolution, fraction of crystal volume occupied by the solvent, number of residues in the asymmetric unit, fraction of apolar protein surface or secondary structure, has been studied. The number of water molecules included in crystallographic models depends primarily on the resolution at which the structure has been solved, while the temperature of the data collection has only marginal influence. On average, at 2.0 A resolution one water molecule per residue is included in the model, while at 1.0 A resolution about 1.6–1.7 are crystallographically located. At 2.0 A resolution the well known rule-of-thumb of `one water per protein residue' is confirmed, though the number of water molecules experimentally observed is strongly dependent on resolution. The results presented are useful in assessing the quality of a protein crystal structure, in selecting structural results to be compared and in evaluating the expected improvement on the solvent structure when increasing the crystallographic resolution.
TL;DR: In this paper, a miniaturized Wollaston wire resistive thermometer was used as a probe to record infrared absorption spectra of polymeric samples by detecting photothermally induced temperature fluctuations at the sample surface.
Abstract: We have used a miniaturized Wollaston wire resistive thermometer as a probe to record infrared absorption spectra of polymeric samples by detecting photothermally induced temperature fluctuations at the sample surface. This method opens the way to absorption Fourier transform infrared spectroscopy/microscopy with a spatial resolution that is no longer diffraction limited, but is determined instead by the size of the contact between probe and sample. At present, this is on the order of a few hundred nanometers. The thermal probe, of a type used in scanning thermal microscopy and microthermal analysis, allows us to detect the photothermal response of a specimen exposed to the beam of a Fourier transform infrared spectrometer and heated thereby. The signal from this probe measures the resulting temperature fluctuations, and thus provides an interferogram which replaces the interferogram normally obtained by means of direct detection of the IR transmitted by a sample.
TL;DR: Tomography is being developed for 3-D imaging, and spectromicroscopy offers unique capabilities for biochemical mapping of unlabelled structures beyond those of gold and fluorescent labels.
TL;DR: In this paper, a technique was developed to obtain three-dimensional structural information on a length scale well below the Rayleigh length with conventional far-field optics by spectrally selecting a single molecule with high-resolution laser spectroscopy and using a CCD camera to register the spatial distribution of the emitted photons in three dimensions.
Abstract: A technique has been developed to obtain three-dimensional structural information on a length scale well below the Rayleigh length with conventional far-field optics. By spectrally selecting a single molecule with high-resolution laser spectroscopy and using a CCD camera to register the spatial distribution of the emitted photons in three dimensions, one can determine the position of a molecule with unprecedented accuracy. One can resolve details in the specimen with sub-diffraction-limited resolution in three dimensions by applying this procedure to as many molecules as are present in the same diffraction-limited volume and obtaining their mutual positions. The feasibility of this technique is demonstrated for the system of pentacene in p-terphenyl at cryogenic temperatures for which molecules were localized with an accuracy of better than 40 nm in the lateral and 100 nm in the axial directions.
TL;DR: In this article, a new type of exposure system employing a multiplicity of 2-photon excitation frequencies which interfere with one another to produce a super-resolution stationary image, exhibiting a true doubling of the spatial resolution.
Abstract: In recent years, with the advent of femtosecond pulse technology, two-photon absorption has commenced to be used for exposing photo-resists. It is natural to ask then, what is the spatial resolution of two-photon lithography? There has already been some discussion of resolution limits in two-photon, scanning confocal fluorescence microscopy. We will find that ordinary two-photon exposure of photo-resist merely enhances the photographic contrast, or gamma. While this improves the spatial resolution somewhat, it does so at the expense of a requirement for tighter control over the incident light intensity. Instead, we introduce a new type of exposure system employing a multiplicity of 2-photon excitation frequencies which interfere with one another to produce a super-resolution stationary image, exhibiting a true doubling of the spatial resolution.
Patent•
14 Sep 1999TL;DR: In this article, the ink feed channels have been eliminated from the central portion of the substrate, and replaced by the Ink feed channels at the edges of the substrategies, where the ink passage from an underside of substrate around both edges of substrate to the vaporization chambers are communicated through an ink passage.
Abstract: An inkjet printhead includes a compact substrate of increased stability and structural integrity to provide a high resolution 600 dot-per-inch nozzle array having a one-half inch swath. A plurality of ink vaporization chambers are respectively aligned with the nozzles in two longitudinal columns, one column extending longitudinally along one edge of the substrate and a second column extending longitudinally along an opposite edge of the substrate, with ink feed channels communicating through an ink passage from an underside of the substrate around both edges of the substrate to the vaporization chambers. The ink feed channels have thereby been eliminated from the central portion of the substrate, and replaced by the ink feed channels at the edges of the substrate.
TL;DR: A high energy resolution electron energy‐loss spectroscopy (EELS) microscope, which can take spectra from specified small specimen areas and specified small reciprocal space areas to investigate detailed electronic structures, is developed.
Abstract: We have developed a high energy resolution electron energy-loss spectroscopy (EELS) microscope, which can take spectra from specified small specimen areas and specified small reciprocal space areas to investigate detailed electronic structures. The EELS microscope is equipped with retarding Wien filters as the monochromator and the analyser. The filters are designed to achieve a stigmatic focus. The energy resolutions are 12 meV and 25 meV for cases without and with a specimen, respectively. Spatial and momentum resolutions are 30–110 nm in diameter and 1.1 nm−1 in angular diameter, respectively. EELS spectra are presented to show the performance of this instrument.
TL;DR: In this article, the first two cobalt neighbor shells with nearly isotropic resolution were obtained, using a combination of normal and inverse, synchrotron and laboratory experiments, and no a priori knowledge of the structure was used.
Abstract: The local atomic environment of Co atoms in a CoO crystal was imaged by hard x-ray holography. The complete three dimensional picture of the first two cobalt neighbor shells with nearly isotropic resolution was obtained, using a combination of normal and inverse, synchrotron and laboratory experiments. No a priori knowledge of the structure was used.
TL;DR: The electron density of l-cystine has been analyzed using 110 K single-crystal Mo Kα X-ray diffraction data to a resolution of (sin θ/λ)max = 1.123 A-1 with a CCD area detector as mentioned in this paper.
Abstract: The electron density of l-cystine has been analyzed using 110 K single-crystal Mo Kα X-ray diffraction data to a resolution of (sin θ/λ)max = 1.123 A-1 with a CCD area detector. Due to the large c-parameter (55.9 A), a discussion is made for choosing the best experimental data collection strategy and data reduction. A multipolar pseudo-atom density model was fitted against the 2309 observed data with I > 3σ(I), [R(F) = 0.014, RW(F) = 0.019, S = 0.73]. The deformation density distribution and topological analysis of charge density clearly reveals disulfide bridge characteristic features and sulfur lone pair electron regions which validate high-level ab initio calculations. The valence shell charge concentration (VSCC) suggests sp3 hybridization of sulfur atoms.
TL;DR: Comparison of the X-ray and electron microscopy results yields a model of how monomeric motor domains bind to the microtubule but the binding of dimeric motors, their stoichiometry, or the influence of nucleotides remains a matter of debate.
TL;DR: An improved electron density map of photosystem I from Synechococcus elongatus calculated at 4-Å resolution for the first time reveals a second phylloquinone molecule and thereby completes the set of cofactors constituting the electron transfer system of this iron-sulfur type photosynthetic reaction center.
TL;DR: In this paper, the synthesis of benzylcyclohexylhexylphenylphosphine and its resolution by means of optically active palladium metallacycles were reported.
TL;DR: In this article, the authors considered two-object resolution from the viewpoint of model fitting theory and showed that the precision is determined by a certain factor, which is a function of the distance of the peaks, their widths and the number of counts.
TL;DR: In this article, a variation of ballistic electron emission microscopy has been developed to image magnetic structure in thin-film multilayers with nanometer resolution, and magnetic domains and domain-wall motion are readily observable with this technique.
Abstract: A variation of ballistic electron emission microscopy has been developed to image magnetic structure in thin-film multilayers with nanometer resolution. In studies of nominally uncoupled Co/Cu/Co trilayer films, magnetic domains and domain-wall motion are readily observable with this technique. In the Co/Cu/Co trilayer system magnetic domains are found to occur on an ∼500-nm-length scale and less, while smaller-scale fluctuations in the ballistic electron transport properties of the system are found on an ∼10 nm length scale.