Electron diffraction from anthracene

1996 ◽  
Vol 54 ◽  
pp. 688-689
Author(s):  
W. F. Tivol ◽  
J. H. Kim
Keyword(s):  
High Resolution ◽  
Electron Diffraction ◽  
Room Temperature ◽  
Three Dimensional ◽  
Zone Axis ◽  
Data Set ◽  
High Resolution Data ◽  
Diffraction Patterns ◽  
Reduced Temperature ◽  
Resolution Data

Collection of a three-dimensional data set from anthracene illustrates some of the difficulties which can be encountered. Since the crystals are grown from solution their orientation is not certain, and the crystals are very bendy, so a range of orientations is encountered at a given tilt setting. Anthracene is moderately labile to irradiation, so care must be taken to avoid radiation damage during data collection. Anthracene will sublime at room temperature under vacuum, so the data must be collected at reduced temperature. Flat, well-ordered areas of the crystals are rare, so collection of high-resolution data is time-consuming. The thickness of the crystals is difficult to control, so finding areas which have minimal multiple scattering is also formidable.The structure of anthracene is already known, so simulations of the diffraction patterns along various zone axes can be made. Cerius 2.0® was used to produce simulated zone axis patterns for all combinations of indices whose absolute values were 3 or less. The preferred orientation for the untilted grid is [102]. Scans of several preparations resulted in patterns which matched the simulation for [102]. The angles for each of the Miller planes with respect to [102] were calculated from the formula given by Dorset.

HRSC-A data: a new high-resolution data set with multipurpose applications in physical geography

2007 ◽  
Vol 31 (2) ◽  
pp. 179-197 ◽  
Author(s):  
J.-C. Otto ◽  
K. Kleinod ◽  
O. König ◽  
M. Krautblatter ◽  
M. Nyenhuis ◽  
...  
Keyword(s):  
High Resolution ◽  
Land Surface ◽  
Research Training ◽  
Spatial Scales ◽  
Three Dimensional ◽  
Physical Geography ◽  
Vegetation Monitoring ◽  
Data Set ◽  
High Resolution Data ◽  
Resolution Data

The analysis and interpretation of remote sensing data facilitates investigation of land surface complexity on large spatial scales. We introduce here a geometrically high-resolution data set provided by the airborne High Resolution Stereo Camera (HRSC-A). The sensor records digital multispectral and panchromatic stereo bands from which a very high-resolution ground elevation model can be produced. After introducing the basic principles of the HRSC technique and data, applications of HRSC data within the multidisciplinary Research Training Group 437 are presented. Applications include geomorphologic mapping, geomorphometric analysis, mapping of surficial grain-size distribution, rock glacier kinematic analysis, vegetation monitoring and three-dimensional landform visualization. A final evaluation of the HRSC data based on three years of multipurpose usage concludes this presentation. A combination of image and elevation data opens up various possibilities for visualization and three-dimensional analysis of the land surface, especially in geomorphology. Additionally, the multispectral imagery of the HRSC data has potential for land cover mapping and vegetation monitoring. We consider HRSC data a valuable source of high-resolution terrain information with high applicability in physical geography and earth system science.

scholarly journals A Global High‐Resolution Data Set of Soil Hydraulic and Thermal Properties for Land Surface Modeling

2019 ◽  
Vol 11 (9) ◽  
pp. 2996-3023 ◽  
Author(s):  
Yongjiu Dai ◽  
Qinchuan Xin ◽  
Nan Wei ◽  
Yonggen Zhang ◽  
Wei Shangguan ◽  
...  
Keyword(s):  
Thermal Properties ◽  
High Resolution ◽  
Land Surface ◽  
Surface Modeling ◽  
Data Set ◽  
High Resolution Data ◽  
Land Surface Modeling ◽  
Soil Hydraulic ◽  
Resolution Data

The influence of resolution on scale-dependent clustering in fracture spacing data

2016 ◽  
Vol 4 (3) ◽  
pp. T387-T394 ◽  
Author(s):  
Ankur Roy ◽  
Atilla Aydin ◽  
Tapan Mukerji
Keyword(s):  
High Resolution ◽  
Spatial Data ◽  
Reservoir Characterization ◽  
Data Capture ◽  
Low Resolution ◽  
Data Set ◽  
Bootstrap Analysis ◽  
High Resolution Data ◽  
Fracture Spacing ◽  
Resolution Data

It is a common practice to analyze fracture spacing data collected from scanlines and wells at various resolutions for the purposes of aquifer and reservoir characterization. However, the influence of resolution on such analyses is not well-studied. Lacunarity is a parameter that is used for multiscale analysis of spatial data. In quantitative terms, at any given scale, it is a function of the mean and variance of the distribution of masses captured by a gliding a window of that scale (size) across any pattern of interest. We have described the application of lacunarity for delineating differences between scale-dependent clustering attributes of data collected at different resolutions along a scanline. Specifically, we considered data collected at different resolutions from two outcrop exposures, a pavement and a cliff section, of the Cretaceous turbititic sandstones of the Chatsworth Formation widely exposed in southern California. For each scanline, we analyzed data from low-resolution aerial or ground photographs and high-resolution ground measurements for scale-dependent clustering attributes. High-resolution data show larger values of scale-dependent lacunarity than their respective low-resolution counterparts. We further performed a bootstrap analysis for each data set to test for the significance of such clustering differences. We started with generating 300 realizations for each data set and then ran lacunarity analysis on them. It was seen that lacunarity for higher resolution data set lay significantly outside the upper 90th percentile values, thus proving that higher resolution data are distinctly different from random and fractures are clustered. We have therefore postulated that lower resolution data capture fracture zones that had relatively uniform spacing, whereas higher resolution data capture thin and short splay joints and sheared joints that contribute to fracture clustering. Such findings have important implications in terms of understanding organization of fractures in fracture corridors, which in turn is critical for modeling and upscaling exercises.

A microscopic system for high-resolution electron crystallography

1995 ◽  
Vol 53 ◽  
pp. 70-71
Author(s):  
Y. Fujiyoshi ◽  
K. Murata ◽  
K. Mitsuoka ◽  
T. Hirai ◽  
A. Miyazawa ◽  
...  
Keyword(s):  
High Resolution ◽  
Structure Analysis ◽  
Room Temperature ◽  
Point Of View ◽  
Irradiation Damage ◽  
High Resolution Data ◽  
Light Harvesting Complex ◽  
Resolution Electron ◽  
Structural Point ◽  
Resolution Data

High-resolution electron cryo-microscopy is one of good candidate for structure analysis of membrane-protein, and also actually analyzed the structure of membrane-proteins such as bacteriorhodopsin (bR) and plant light-harvesting complex (LHC). By developing an expeditious method for structure analysis up to atomic or near atomic resolution, we would like to interpret a function of protein from the structural point of view. However, there are some difficulties in electron microscopy for structure analysis of protein. Especially, the most serious problems are the specimen damage caused by electron irradiation, the denaturation of biomolecules caused by dehydration and missing high-resolution data on electron micrographs at high-tilted angle.The irradiation damage at 8K has been found to be reduced to 1/20 compared with that at room temperature. We have, therefore, developed a high-resolution electron cryo-microscope and improved it by which images can be recorded with higher resolution than 3 Å at a specimen-stage temperature of 4.2 K, even when the specimen is highly tilted. The highly tilted data are essential for reduction of the missing corn effect.

scholarly journals Crambin - record in crystallographic resolution for a biological macromolecule

2014 ◽  
Vol 70 (a1) ◽  
pp. C1202-C1202
Author(s):  
Johanna Kallio ◽  
Victor Lamzin
Keyword(s):  
High Resolution ◽  
Data Interpretation ◽  
High Energy ◽  
Structural Features ◽  
Biological Macromolecule ◽  
Data Set ◽  
Synchrotron Source ◽  
Small Protein ◽  
High Resolution Data ◽  
Resolution Data

A couple of years ago a study was presented that set the record for the highest X-ray crystallographic resolution for a biological macromolecule [1]. The structure of the small protein crambin was determined to 0.48 Å resolution - this almost doubled the amount of available experimental data. Crambin is a small protein consisting of 46 amino acids belonging to the thionin family. Although the protein and its structure has long been known, it lacks any obvious enzymatic activity and has a hard-to-guess biological function. The protein crystallizes readily and serves as an excellent specimen for exploring the limits of resolution of the diffraction. The results demonstrated the possibilities that can be offered by a high-energy synchrotron source. The structure refined with Refmac, Shelxl and Mopro revealed a wealth of details. Bonding electron density became visible along the main chain. However, no fundamental additional structural features could be detected in comparison to the previously collected data set to 0.54 Å resolution. The availability of extremely high-resolution data is certainly of great help to drive further software development and methods for data interpretation. The question will always remain as to what the true limits are in terms of what can be seen in a biological macromolecule. Here we will present the results of our recent efforts in interpretation of such ultra-high resolution data.

scholarly journals Decadal surface temperature trends in India based on a new high-resolution data set

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Robert S. Ross ◽  
T. N. Krishnamurti ◽  
Sandeep Pattnaik ◽  
D. S. Pai
Keyword(s):  
High Resolution ◽  
Surface Temperature ◽  
Data Set ◽  
High Resolution Data ◽  
Temperature Trends ◽  
Resolution Data

[001] imaging of rutile: A problem in high-resolution microscopy

1983 ◽  
Vol 41 ◽  
pp. 292-293
Author(s):  
Peter G. Self ◽  
Peter R. Buseck
Keyword(s):  
High Resolution ◽  
Electron Diffraction ◽  
Computer Simulations ◽  
Zone Axis ◽  
Severe Problem ◽  
Diffraction Patterns ◽  
High Resolution Microscopy

HRTEM images of the [001] zone of rutile (fig. 1) show 0.32 nm fringes near the edge of the crystal, but these rapidly change to 0.46 nm in the thicker parts of the crystal. This change in spacing is only possible if the intensities in the dynamically forbidden {100} reflections become comparable to the intensities of the {110} reflections. The {100} reflections are dynamically forbidden because the structure has 2-fold screw axes parallel to a and b and n-glides perpendicular to a and b. The presence of 0.46 nm rather than 0.32 nm fringe spacings in images of the thicker crystal regions presents a severe problem in matching the images to computer simulations. Fig. 2 shows [001] zone axis images for thin and thick crystals. As expected from symmetry, the computed images show only 0.32 nm spacings. In an attempt to explain the mismatch between computed and experimental images several effects not normally included in image calculations, and which could cause a change in the symmetry of electron diffraction patterns, were investigated, all without success.

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