Journal articles: 'Shape preferred orientation'

1

Mardinly, A. John, Lawrence H. van Vlack, and William F. Hosford. "Preferred Orientation of MnS Inclusions in Rolled Steel." Textures and Microstructures 22, no. 2 (January 1, 1993): 127–38. http://dx.doi.org/10.1155/tsm.22.127.

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The preferred orientation of MnS inclusions in hot-rolled steel was studied by electron diffraction. Specimens of resulfurized steel were examined after casting and after hot rolling to true strains of 0.5, 1.0 and 1.5. After rolling, the orientations of the inclusions tended toward an ideal 〈100〉 {001}. Only a moderate correlation between the final inclusion shape and orientation was found.

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2

Simigian, Sandra, and John Starkey. "A discussion of pyrrhotite fabrics." Canadian Journal of Earth Sciences 24, no. 5 (May 1, 1987): 1070–71. http://dx.doi.org/10.1139/e87-103.

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The classification of pyrrhotite fabrics proposed by Lusk and Ostwald identifies E-type pyrrhotite, which has no dimensional or crystallographic preferred orientation and an equant grain shape, and F-type pyrrhotite, which has a distinct dimensional and crystallographic preferred orientation and flattened, elongate grain shapes. The results of an analysis of pyrrhotite fabrics studied for Ducktown, Tennessee, do not conform with this classification. The data suggest that the three parameters, crystallographic orientation, dimensional orientation, and grain shape, are independent. Therefore, the E- and F-type classification of pyrrhotite fabrics appears not to have universal applicability.

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Kuo, Li-Ying, and Pouyan Shen. "Shape dependent coalescence and preferred orientation of CeO2 nanocrystallites." Materials Science and Engineering: A 277, no. 1-2 (January 2000): 258–65. http://dx.doi.org/10.1016/s0921-5093(99)00547-x.

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4

Allard, B., and K. Benn. "Shape preferred-orientation analysis using digitized images on a microcomputer." Computers & Geosciences 15, no. 3 (January 1989): 441–48. http://dx.doi.org/10.1016/0098-3004(89)90049-6.

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Lamprecht, Sebastian, Johannes Stoffels, and Thomas Udelhoven. "ALS as Tool to Study Preferred Stem Inclination Directions." Remote Sensing 12, no. 22 (November 13, 2020): 3744. http://dx.doi.org/10.3390/rs12223744.

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Although gravitropism forces trees to grow vertically, stems have shown to prefer specific orientations. Apart from wind deforming the tree shape, lateral light can result in prevailing inclination directions. In recent years a species dependent interaction between gravitropism and phototropism, resulting in trunks leaning down-slope, has been confirmed, but a terrestrial investigation of such factors is limited to small scale surveys. ALS offers the opportunity to investigate trees remotely. This study shall clarify whether ALS detected tree trunks can be used to identify prevailing trunk inclinations. In particular, the effect of topography, wind, soil properties and scan direction are investigated empirically using linear regression models. 299.000 significantly inclined stems were investigated. Species-specific prevailing trunk orientations could be observed. About 58% of the inclination and 19% of the orientation could be explained by the linear models, while the tree species, tree height, aspect and slope could be identified as significant factors. The models indicate that deciduous trees tend to lean down-slope, while conifers tend to lean leeward. This study has shown that ALS is suitable to investigate the trunk orientation on larger scales. It provides empirical evidence for the effect of phototropism and wind on the trunk orientation.

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Yoshikawa, Noboru, Takanori Endo, Shoji Taniguchi, Satoshi Awaji, Kazuo Watanabe, and Eiji Aoyagi. "Microstructure and orientation of iron crystals by thermal chemical vapor deposition with imposition of magnetic field." Journal of Materials Research 17, no. 11 (November 2002): 2865–74. http://dx.doi.org/10.1557/jmr.2002.0416.

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Iron crystals were deposited by thermally activated chemical vapor deposition with imposition of magnetic field. In this study, the deposition was conducted by imposing a magnetic field up to 3.5 T in a temperature range between 0.48 and 0.51 of TmFe (melting point of iron), which is below the Curie point of iron (0.58 TmFe). The microstructures and crystal orientations of the deposits were investigated. In the deposition process, island-shaped crystals were formed on a scale of several microns; then a film was grown by their coalescence. As the magnetic field magnitude increased, population of the island-shaped crystals having a cubic shape increased. Simultaneously, their ω-scanned (200) profile became sharper. Their degree of (100) preferred orientation was dependent on the magnetic field up to 3.5 T, which is usually high enough for the saturated magnetization of iron crystals. However, when the substrate was placed parallel to the magnetic field, (100) preferred orientation was not observed for the island-shaped crystals. A large and bimodal ω-scanned (110) profile having sharp peaks was obtained when the substrate was inclined 45° to the field. Preferred (100) orientation was not obtained from the iron films, for which two reasons were pointed out. The first is the secondary grown crystals on the island-shaped crystals having different orientations, and the second is the observed zone III grain structure of the films, where grain boundary migration occurred.

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Tatiparti, Sankara Sarma V., and Fereshteh Ebrahimi. "Preferred orientation and shape of electrodeposited nanocrystalline Al–Mg alloy dendrites." Materials Letters 65, no. 12 (June 2011): 1915–18. http://dx.doi.org/10.1016/j.matlet.2011.04.018.

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Barnard, A. S., and L. A. Curtiss. "Modeling the preferred shape, orientation and aspect ratio of gold nanorods." Journal of Materials Chemistry 17, no. 31 (2007): 3315. http://dx.doi.org/10.1039/b704798c.

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Sen, Koushik, and Manish A. Mamtani. "Magnetic fabric, shape preferred orientation and regional strain in granitic rocks." Journal of Structural Geology 28, no. 10 (October 2006): 1870–82. http://dx.doi.org/10.1016/j.jsg.2006.07.005.

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10

Jee, K. K., M. C. Shin, and Y. G. Kim. "Preferred orientation and reversible shape memory effect in Ti“Ni alloy." Scripta Metallurgica et Materialia 24, no. 5 (May 1990): 921–26. http://dx.doi.org/10.1016/0956-716x(90)90138-7.

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11

Launeau, Patrick, Jean-Luc Bouchez, and Keith Benn. "Shape preferred orientation of object populations: automatic analysis of digitized images." Tectonophysics 180, no. 2-4 (August 1990): 201–11. http://dx.doi.org/10.1016/0040-1951(90)90308-u.

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12

Ong, S. Y., M. Chipaux, A. Nagl, and R. Schirhagl. "Shape and crystallographic orientation of nanodiamonds for quantum sensing." Physical Chemistry Chemical Physics 19, no. 17 (2017): 10748–52. http://dx.doi.org/10.1039/c6cp07431f.

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Fluorescent nanodiamonds are revealed to have flake-like geometries and a preferred orientation in (110) direction. The consequences for their magnetic sensing purposes and performance in experiments for physics and biology are discussed in this paper.

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13

Kang, Liping, Lingli Wang, Haiyan Wang, Xiaodong Zhang, and Yongqiang Wang. "Preparation and Performance of Gallium Nitride Powders with Preferred Orientation." MATEC Web of Conferences 142 (2018): 01009. http://dx.doi.org/10.1051/matecconf/201814201009.

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The paper prepared the III-V semiconductor, hexagonal wurtzite Gallium nitride powders by calcining a gallium oxide in flowing ammonia above 900 °C (1173K). Because of the solid-state reaction process that the gallium oxide transformed to GaN through solid-state gallium oxynitrides (GaOxNy) as inter-mediates, the Gallium nitride powders which are agglomerates of tens nanometers flake crystallites retain the rod shape and grain size of raw gallium oxide and have slight (002) plane preferred orientation. The near-edge emission of Gallium nitride at 346 nm has a blue shift of 187 meV attributed to a decrease in disorder of the material that is decided by the (002) plane preferred orientation. The preferred orientation and a blue shift have some kind of reference significance to single crystal growth.

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Calvet, Marie, and Ludovic Margerin. "Shape preferred orientation of iron grains compatible with Earth's uppermost inner core hemisphericity." Earth and Planetary Science Letters 481 (January 2018): 395–403. http://dx.doi.org/10.1016/j.epsl.2017.10.038.

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15

Kanitpanyacharoen, Waruntorn, Roman Vasin, Hans-Rudolf Wenk, and David N. Dewhurst. "Linking preferred orientations to elastic anisotropy in Muderong Shale, Australia." GEOPHYSICS 80, no. 1 (January 1, 2015): C9—C19. http://dx.doi.org/10.1190/geo2014-0236.1.

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The significance of shales for unconventional hydrocarbon reservoirs, nuclear waste repositories, and geologic carbon storage has opened new research frontiers in geophysics. Among many of its unique physical properties, elastic anisotropy had long been investigated by experimental and computational approaches. Here, we calculated elastic properties of Cretaceous Muderong Shale from Australia with a self-consistent averaging method based on microstructural information. The volume fraction and crystallographic preferred orientation distributions of constituent minerals were based on synchrotron x-ray diffraction experiments. Aspect ratios of minerals and pores, determined from scanning electron microscopy, were introduced in the self-consistent averaging. Our analysis suggested that phyllosilicates (i.e., illite-mica, illite-smectite, kaolinite, and chlorite) were dominant with [Formula: see text]. The shape of clay platelets displayed an average aspect ratio of 0.05. These platelets were aligned parallel to the bedding plane with a high degree of preferred orientation. The estimated porosity at ambient pressure was [Formula: see text] and was divided into equiaxial pores and flat pores with an average aspect ratio of 0.01. Our model gave results that compared satisfactorily with values derived from ultrasonic velocity measurements, confirming the validity and reliability of our approximations and averaging approach.

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DiBenedetto, Michelle H., and Nicholas T. Ouellette. "Preferential orientation of spheroidal particles in wavy flow." Journal of Fluid Mechanics 856 (October 12, 2018): 850–69. http://dx.doi.org/10.1017/jfm.2018.738.

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We report a theoretical study of the angular dynamics of small, non-inertial spheroidal particles in a linear wave field. We recover the observation recently reported by DiBenedetto et al. (J. Fluid Mech., vol. 837, 2018, pp. 320–340) that the orientation of these spheroids tends to a stable limit cycle consisting of a preferred value with a superimposed oscillation. We show that this behaviour is a consequence of finite wave amplitude and is the angular analogue of Stokes drift. We derive expressions for both the preferred orientation of the particles, which depends only on particle shape, and the amplitude of the oscillation about this preferred value, which additionally depends on the wave parameters and the depth of the particle in the water column.

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17

Li, Taotao, Liuwei Zheng, Wanggang Zhang, and Pengfei Zhu. "Determining the Preferred Orientation of Silver-Plating via X-ray Diffraction Profile." Nanomaterials 11, no. 9 (September 17, 2021): 2417. http://dx.doi.org/10.3390/nano11092417.

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Determining the preferred orientation of plating film is of practical importance. In this work, the Rietveld method and quantitative texture analysis (RM+QTA) are used to analyze the preferred orientation of plating silver film with XRD profile, whose <311> axial texture can be completely described by a set of exponential harmonics index, extracted from a single XRD profile, C41,1(0.609), C61,1(0.278), C81,1(−0.970). The constructed pole figures with the index of the exponential harmonic are following those measured by the multi-axis diffractometer. The method using exponential harmonic index can be extended to characterize the plating by electroplating in a quantitative harmonic description. In addition, a new dimension involving crystallite shape and size is considered in characterizing the preferred orientation.

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18

Yu, Xiao Jiao, Xin Ming Li, and Qian Yang. "Effect of KCl on Crystal Morphology of Electrodepisited Cu₂O Thin Films." Advanced Materials Research 239-242 (May 2011): 2827–30. http://dx.doi.org/10.4028/www.scientific.net/amr.239-242.2827.

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Different morphology of Cu2O crystals were fabricated by electrochemical deposition using ITO and ITO/nano-TiO2 as working electrode. The effect of different KCl concentrations on the microstructure and surface morphology of Cu2O thin films were studied and the morphology controlled mechanism was also discussed. When the concentration of KCl was 7mmol/L, the shape of Cu2O crystals evolved from dentrite to similar cube on the ITO matrix. When the concentration of KCl was 5mmol/L, the shape of Cu2O crystals evolves from regular octahedron ({111} preferred orientation) to truncated cube ({100} preferred orientation) on the ITO/nano-TiO2 matrix. The results also indicate that the substrates played a key role in the particle size control.

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Zel, Ivan, Bekhzodjon Abdurakhimov, Sergey Kichanov, Olga Lis, Elmira Myrzabekova, Denis Kozlenko, Mannab Tashmetov, Khalbay Ishbaev, and Kuatbay Kosbergenov. "Neutron Tomography Studies of Two Lamprophyre Dike Samples: 3D Data Analysis for the Characterization of Rock Fabric." Journal of Imaging 8, no. 3 (March 19, 2022): 80. http://dx.doi.org/10.3390/jimaging8030080.

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The rock fabric of two lamprophyre dike samples from the Koy-Tash granitoid intrusion (Koy-Tash, Jizzakh region, Uzbekistan) has been studied, using the neutron tomography method. We have performed virtual segmentation of the reconstructed 3D model of the tabular igneous intrusion and the corresponding determination of dike margins orientation. Spatial distributions of inclusions in the dike volume, as well as further analysis of size distributions and shape orientations of inclusions, have been obtained. The observed shape preferred orientations of inclusions as evidence of the magma flow-related fabric. The obtained structural data have been discussed in the frame of the models of rigid particle motion and the straining of vesicles in a moving viscous fluid.

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Stünitz, Holger. "Folding and shear deformation in quartzites, inferred from crystallographic preferred orientation and shape fabrics." Journal of Structural Geology 13, no. 1 (January 1991): 71–86. http://dx.doi.org/10.1016/0191-8141(91)90102-o.

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Pehl, J., Siegfried Matthies, H. R. Wenk, Luca Lutterotti, and Sven C. Vogel. "Quantitative Texture Analysis with the HIPPO TOF Diffractometer." Materials Science Forum 495-497 (September 2005): 113–18. http://dx.doi.org/10.4028/www.scientific.net/msf.495-497.113.

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One of the design goals of the neutron time-of-flight (TOF) diffractometer HIPPO (HIgh Pressure - Preferred Orientation) at LANSCE (Los Alamos Neutron Science Center) was efficient quantitative texture analysis. In this paper, the effects of the HIPPO detector geometry and layout on texture analysis, particularly the shape and dimensions of the detector panels, are investigated. An aluminum sample with a strong and asymmetric texture was used to determine the methodological limitations of various methods of quantitative texture analysis. Several algorithms for extracting the orientation distribution function (ODF) from the TOF-spectra are compared: discrete orientations at arbitrary positions, harmonic method in Rietveld codes (MAUD and GSAS) and discrete methods in MAUD. All methods provide a similar representation of the main texture component, but discrete methods have a fundamental advantage over harmonic methods in characterizing regions of the ODF with low orientation densities. For HIPPO data of the present sample, harmonic expansions beyond lmax= 12 introduce subsidiary maxima and minima, which are consistently identified as artifacts. The results of our analysis establishes HIPPO as an efficient instrument to quantitatively determine preferred orientations in relatively short measuring times, if the texture features are not exceedingly sharp (full-width at half-maximum (FWHM) in the ODF > 20-30°).

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Wang, Ji Jie, B. L. Wu, Z. W. Huang, Tong Cui, Yan Dong Wang, Ryosuke Kainuma, and Kiyohito Ishida. "Stress-Induced Lattice Transit Behavior in a Cold-Rolled Cu-Al-Mn Two-Way Shape Memory Alloy." Materials Science Forum 561-565 (October 2007): 1445–49. http://dx.doi.org/10.4028/www.scientific.net/msf.561-565.1445.

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The effect of cold rolling on two-way shape memory was investigated by x-ray diffraction technique and TEM in a Cu-18Al-10.5Mn (at.%) alloy. Cold rolling leads to a preferred orientation distribution on the stress-induced martensite with 6M-structure, which leads to the dependence of two-way shape memory on the specimen directions. The relationship of stress state and anisotropy of 6M-structured martensite lattice inside cold rolling deforming region is elucidated through analyzing the deformation process-related variant selection according to original grain orientation.

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Wong, Margaret N., Timothy P. Nguyen, Ting-Hsuan Chen, Jeffrey J. Hsu, Xingjuan Zeng, Aman Saw, Eric M. Demer, Xin Zhao, Yin Tintut, and Linda L. Demer. "Preferred mitotic orientation in pattern formation by vascular mesenchymal cells." American Journal of Physiology-Heart and Circulatory Physiology 303, no. 12 (December 15, 2012): H1411—H1417. http://dx.doi.org/10.1152/ajpheart.00625.2012.

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Cellular self-organization is essential to physiological tissue and organ development. We previously observed that vascular mesenchymal cells, a multipotent subpopulation of aortic smooth muscle cells, self-organize into macroscopic, periodic patterns in culture. The patterns are produced by cells gathering into raised aggregates in the shape of nodules or ridges. To determine whether these patterns are accounted for by an oriented pattern of cell divisions or postmitotic relocation of cells, we acquired time-lapse, videomicrographic phase-contrast, and fluorescence images during self-organization. Cell division events were analyzed for orientation of daughter cells in mitoses during separation and their angle relative to local cell alignment, and frequency distribution of the mitotic angles was analyzed by both histographic and bin-free statistical methods. Results showed a statistically significant preferential orientation of daughter cells along the axis of local cell alignment as early as day 8, just before aggregate formation. This alignment of mitotic axes was also statistically significant at the time of aggregate development ( day 11) and after aggregate formation was complete ( day 15). Treatment with the nonmuscle myosin II inhibitor, blebbistatin, attenuated alignment of mitotic orientation, whereas Rho kinase inhibition eliminated local cell alignment, suggesting a role for stress fiber orientation in this self-organization. Inhibition of cell division using mitomycin C reduced the macroscopic pattern formation. Time-lapse monitoring of individual cells expressing green fluorescent protein showed postmitotic movement of cells into neighboring aggregates. These findings suggest that polarization of mitoses and postmitotic migration of cells both contribute to self-organization into periodic, macroscopic patterns in vascular stem cells.

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Sitepu, H., Heinz Günter Brokmeier, Daniel Chateigner, and J. P. Wright. "Crystallographic Phase Composition and Structural Analysis of Ti-Ni-Fe Shape Memory Alloy by Synchrotron Diffraction." Solid State Phenomena 105 (July 2005): 139–44. http://dx.doi.org/10.4028/www.scientific.net/ssp.105.139.

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The preferred crystallographic orientation (i.e. texture) and the non-transformed austenite can cause serious systematic errors in the structural study of the R-phase in 50.75at.%Ti- 47.75at.%Ni-1.50at.%Fe (hereafter referred to as Ti-Ni-Fe ternary) shape memory alloy. The crystal structure refinement of R-phase synchrotron high resolution powder diffraction (SRD) data using Rietveld refinement with generalized spherical harmonic (GSH) description for preferred orientation correction showed that the sample consists of minor cubic phase and the space group was 3 P [1]. The objective of the present paper is to study the crystallographic phase composition and crystal structure refinement of SRD data of trigonal R-phase martensite and monoclinic (B19¢) martensite in Ti-Ni-Fe ternary alloy during thermal cycling using the GSH description.

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Cuijpers, Raymond H., Jeroen B. J. Smeets, and Eli Brenner. "On the Relation Between Object Shape and Grasping Kinematics." Journal of Neurophysiology 91, no. 6 (June 2004): 2598–606. http://dx.doi.org/10.1152/jn.00644.2003.

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Despite the many studies on the visual control of grasping, little is known about how and when small variations in shape affect grasping kinematics. In the present study we asked subjects to grasp elliptical cylinders that were placed 30 and 60 cm in front of them. The cylinders' aspect ratio was varied systematically between 0.4 and 1.6, and their orientation was varied in steps of 30°. Subjects picked up all noncircular cylinders with a hand orientation that approximately coincided with one of the principal axes. The probability of selecting a given principal axis was the highest when its orientation was equal to the preferred orientation for picking up a circular cylinder at the same location. The maximum grip aperture was scaled to the length of the selected principal axis, but the maximum grip aperture was also larger when the length of the axis orthogonal to the grip axis was longer than that of the grip axis. The correlation between the grip aperture— or the hand orientation—at a given instant, and its final value, increased monotonically with the traversed distance. The final hand orientation could already be inferred from its value after 30% of the movement distance with a reliability that explains 50% of the variance. For the final grip aperture, this was only so after 80% of the movement distance. The results indicate that the perceived shape of the cylinder is used for selecting appropriate grasping locations before or early in the movement and that the grip aperture and orientation are gradually attuned to these locations during the movement.

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Sawaguchi, Takashi, and Kazuhiko Ishii. "Three-dimensional numerical modeling of lattice- and shape-preferred orientation of orthopyroxene porphyroclasts in peridotites." Journal of Structural Geology 25, no. 9 (September 2003): 1425–44. http://dx.doi.org/10.1016/s0191-8141(02)00199-2.

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Davis, Joshua R., and Scott Giorgis. "An inverse approach to constraining strain and vorticity using rigid clast shape preferred orientation data." Journal of Structural Geology 68 (November 2014): 337–46. http://dx.doi.org/10.1016/j.jsg.2014.05.027.

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Heilbronner, Renée, and Rüdiger Kilian. "The grain size(s) of Black Hills Quartzite deformed in the dislocation creep regime." Solid Earth 8, no. 5 (October 17, 2017): 1071–93. http://dx.doi.org/10.5194/se-8-1071-2017.

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Abstract. General shear experiments on Black Hills Quartzite (BHQ) deformed in the dislocation creep regimes 1 to 3 have been previously analyzed using the CIP method (Heilbronner and Tullis, 2002, 2006). They are reexamined using the higher spatial and orientational resolution of EBSD. Criteria for coherent segmentations based on c-axis orientation and on full crystallographic orientations are determined. Texture domains of preferred c-axis orientation (Y and B domains) are extracted and analyzed separately. Subdomains are recognized, and their shape and size are related to the kinematic framework and the original grains in the BHQ. Grain size analysis is carried out for all samples, high- and low-strain samples, and separately for a number of texture domains. When comparing the results to the recrystallized quartz piezometer of Stipp and Tullis (2003), it is found that grain sizes are consistently larger for a given flow stress. It is therefore suggested that the recrystallized grain size also depends on texture, grain-scale deformation intensity, and the kinematic framework (of axial vs. general shear experiments).

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Launeau, Patrick. "Evidence of magmatic flow by 2-D image analysis of 3-D shape preferred orientation distributions." Bulletin de la Société Géologique de France 175, no. 4 (July 1, 2004): 331–50. http://dx.doi.org/10.2113/175.4.331.

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Abstract The 3-D Shape Preferred Orientation (SPO) ellipsoid can be obtained by image analysis on a minimum of three perpendicular sections, when the 2-D measurements can be assimilated to ellipses. As numerous phenomenons can modify the SPO in magma (boundary condition effects, crystal interactions, joint migrations, etc.), the ellipsoid calculation is first tested on a set of digital models of simple shear flow. Those models, made of scattered shape ratio distribution, show that a suspension of crystals in a simple shear flow of the magma produces SPO parallel to the shear direction with an intensity given by the average shape ratio of the crystals, without any link with the amount of shear flow. This steady state SPO along the flow direction is particularly useful to study magma emplacement even if it is also shown that a critical shear rate γ between 4 and 8, for crystal shape ratio between 2 and 5 respectively, is sufficient to completely reorient a SPO. Therefore the SPO does not record magmatic strain as may do an enclave, which is an interface between two magmas with low viscosity contrast, that can record the whole strain of the magma by its passive deformation along the flow. An infinite strain is necessary here to parallelize the enclave on the shear flow direction. The application to a natural case (gabbronorite of the Bushveld, South Africa) shows that we must take care of the mineral chosen to describe a flow in a magma and that a careful classical study of the structures observed in thin sections is always required. To allow anyone to test the quality of the 2-D/3-D conversions, a web site is associated to this publication with a free access to all the image analysis and ellipsoid programs presented below.

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Sitepu, Husin. "Texture and structural refinement using neutron diffraction data from molybdite (MoO3) and calcite (CaCO3) powders and a Ni-rich Ni50.7Ti49.30 alloy." Powder Diffraction 24, no. 4 (December 2009): 315–26. http://dx.doi.org/10.1154/1.3257906.

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Preferred orientation or texture is a common feature of experimental powder patterns. The mathematics of two commonly used models for preferred orientation—the March-Dollase and the generalized spherical-harmonic models—is reviewed. Both models were applied individually to neutron powder data from uniaxially pressed molybdite (MoO3) and calcite (CaCO3) powders in Rietveld analyses, as well as the as-received powders. The structural refinement results are compared to single-crystal structures. The results indicate that reasonable refinement of crystal structures can be obtained using either the March model or generalized spherical-harmonic description. However, the generalized spherical-harmonic description provided better Rietveld fits than the March model for the molybdite and calcite. Therefore, the generalized spherical-harmonic description is recommended for correction of preferred orientation in neutron diffraction analysis for both crystal structure refinement and phase composition analysis. Subsequently, the generalized spherical-harmonic description is extended to crystal structure refinement of annealed and the aged polycrystalline Ni-rich Ni50.7Ti49.30 shape memory alloys.

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Helming, K., D. Schmidt, and K. Ullemeyer. "Preferred Orientations of Mica Bearing Rocks Described by Texture Components." Textures and Microstructures 25, no. 2-4 (January 1, 1996): 211–22. http://dx.doi.org/10.1155/tsm.25.211.

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Up to now Texture investigations of phyllosilicates were restricted to pole density measurements of the (001) basal plane. Because of the tabular grain shape parallel to the basal plane an axial symmetry of the texture is assumed usually. This assumption was proved for four mica bearing samples by calculating the ODF from neutron diffraction data. Beside the mica-texture the textures of the other major fractions like quartz and feldspar were determined to detect correlation between them. The textures are explained by components. Each component is characterised by a preferred orientation or fibre axis, a corresponding spreading and an intensity Iʿ describing the volume fraction of all crystallites belonging to the component. The presented component method can be applied to any crystal symmetry and to polyphase materials with overlapped pole figures.

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Lan, Lei Lei, Dan Zhou, Guang Rui Gu, Bao Jia Wu, and Lian Hua Tian. "The Preparation of the Highly Preferred Orientation of Wurtzite Structure Zinc Oxide Films." Advanced Materials Research 936 (June 2014): 287–92. http://dx.doi.org/10.4028/www.scientific.net/amr.936.287.

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Zinc oxide (ZnO) films are prepared on n-Si substrates by means of radio frequency (RF) magnetron sputtering method. The influences of substrate temperature on the crystal orientation and crystalline structure of ZnO films are investigated by X-ray diffraction (XRD) and Raman spectroscopy. The surface morphologies are studied by scanning electron microscope (SEM). It is indicated that ZnO films with wurtzite structure were successfully prepared. When the substrate temperature reduced to 100°C, the wurtzite structure with highly preferred orientation along the (002) plane of the ZnO film is prepared and the elliptical shape particles distributed uniformly on the ZnO film surface. The higher substrate temperature can offer more kinetic energy for mobility of particle on the surface to achieve other crystalline growth, resulting in the highly c-axis-oriented crystalline structure is destroyed.

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Michalík, Martin, Monika Biela, Denisa Cagardová, and Vladimír Lukeš. "Influence of catecholic ring torsion on hydroxyflavones." Acta Chimica Slovaca 13, no. 1 (April 1, 2020): 49–55. http://dx.doi.org/10.2478/acs-2020-0008.

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AbstractSystematic quantum chemical investigation of quercetin and selected eight mono- and bihydroxyflavonols is presented. Structural analysis based on the Density Functional Theory showed that the energetically preferred conformation of flavonols substituted at the C5 and C3 atoms by a hydroxyl group is stabilised via intramolecular hydrogen bonds occurring between the (C4)O···HO(3 or 5) atomic pairs. Depending on the hydroxyl group positions, energetically preferred torsional orientation of the phenyl ring with respect to the planar benzo-γ-pyrone moiety changed from 0 to 180 degrees. Gas-phase electron transitions were investigated using the time-dependent DFT treatment. The dependence of maximal wavelengths on the torsional deformation of the phenyl ring is of a similar shape, i.e. minima observed for the perpendicular orientation and maxima for the planar one. Shape and energies of the Highest Occupied (HOMO) and Lowest Unoccupied (LUMO) Molecular Orbitals were compared. The obtained theoretical results were compared with available experimental data.

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Murata, Akira, Vittorio Gallese, Giuseppe Luppino, Masakazu Kaseda, and Hideo Sakata. "Selectivity for the Shape, Size, and Orientation of Objects for Grasping in Neurons of Monkey Parietal Area AIP." Journal of Neurophysiology 83, no. 5 (May 1, 2000): 2580–601. http://dx.doi.org/10.1152/jn.2000.83.5.2580.

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In this study, we mainly investigated the visual selectivity of hand-manipulation-related neurons in the anterior intraparietal area (area AIP) while the animal was grasping or fixating on three-dimensional (3D) objects of different geometric shapes, sizes, and orientations. We studied the activity of 132 task-related neurons during the hand-manipulation tasks in the light and in the dark, as well as during object fixation. Seventy-seven percent (101/132) of the hand-manipulation-related neurons were visually responsive, showing either lesser activity during manipulation in the dark than during that in the light (visual-motor neurons) or no activation in the dark (visual-dominant neurons). Of these visually responsive neurons, more than half ( n = 66) responded during the object-fixation task (object-type). Among these, 55 were tested for their shape selectivity during the object-fixation task, and many ( n = 25) were highly selective, preferring one particular shape of the six different shapes presented (ring, cube, cylinder, cone, sphere, and square plate). For 28 moderately selective object-type neurons, we performed multidimensional scaling (MDS) to examine how the neurons encode the similarity of objects. The results suggest that some moderately selective neurons responded preferentially to common geometric features shared by similar objects (flat, round, elongated, etc.). Moderately selective nonobject-type visually responsive neurons, which did not respond during object fixation, were found by MDS to be more closely related to the handgrip than to the object shape. We found a similar selectivity for handgrip in motor-dominant neurons that did not show any visual response. With regard to the size of the objects, 16 of 26 object-type neurons tested were selective for both size and shape, whereas 9 object-type neurons were selective for shape but not for size. Seven of 12 nonobject-type and all (8/8) of the motor-dominant neurons examined were selective for size, and almost all of them were also selective for objects. Many hand-manipulation-related neurons that preferred the plate and/or ring were selective for the orientation of the objects (17/20). These results suggest that the visual responses of object-type neurons represent the shape, size, and/or orientation of 3D objects, whereas those of the nonobject-type neurons probably represent the shape of the handgrip, grip size, or hand-orientation. The activity of motor-dominant neurons was also, in part, likely to represent these parameters of hand movement. This suggests that the dorsal visual pathway is concerned with the aspect of form, orientation, and/or size perception that is relevant for the visual control of movements.

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Maixner, J., and P. Kačer. "X-ray powder diffraction data for acetamidinium formate C3H8N2O2, elimination of preferred orientation effect." Powder Diffraction 32, no. 4 (September 26, 2017): 268–70. http://dx.doi.org/10.1017/s0885715617000987.

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X-ray powder diffraction data, unit-cell parameters, and space group for acetamidinium formate, C3H8N2O2, are reported [a = 6.4564(5) Å, c = 13.021 (3) Å, unit-cell volume V = 542.8(3) Å3, M.p. = 215(1)°C, ρc = 1.274 g.cm−3, ρm = 1.269 g.cm−3, Z = 4, and space group P43212]. The front-loaded technique got sample with strong preferred orientation because of plate-like shape of crystallites, so the capillary packing was used for final powder data collection. All measured lines were indexed and are consistent with the P43212 space group. No detectable impurities were observed.

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Bate, P. S., and W. B. Hutchinson. "Imposed stress and variant selection: the role of symmetry and initial texture." Journal of Applied Crystallography 41, no. 1 (January 16, 2008): 210–13. http://dx.doi.org/10.1107/s0021889807055458.

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The paper discusses the role of stress on displacive phase transformations where plasticity is associated with variant selection, together with its implications for the resulting texture. In cases where the parent phase has a texture, the presence of stress generally leads to modification and strengthening of the texture in the product phase. However, if no preferred orientation is present initially, it is shown that the resulting product will be essentially free from texture irrespective of the applied stress. By analysis of the energy product of transformations under stress where the shape-change strain transforms as a second-order tensor, crystallographically indistinguishable orientations can give different energy products, while very different orientations can give the same energy product.

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Nauhaus, Ian, and Dario L. Ringach. "Precise Alignment of Micromachined Electrode Arrays With V1 Functional Maps." Journal of Neurophysiology 97, no. 5 (May 2007): 3781–89. http://dx.doi.org/10.1152/jn.00120.2007.

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Recent theoretical models of primary visual cortex predict a relationship between receptive field properties and the location of the neuron within the orientation maps. Testing these predictions requires the development of new methods that allow the recording of single units at various locations across the orientation map. Here we present a novel technique for the precise alignment of functional maps and array recordings. Our strategy consists of first measuring the orientation maps in V1 using intrinsic optical imaging. A micromachined electrode array is subsequently implanted in the same patch of cortex for electrophysiological recordings, including the measurement of orientation tuning curves. The location of the array within the map is obtained by finding the position that maximizes the agreement between the preferred orientations measured electrically and optically. Experimental results of the alignment procedure from two implementations in monkey V1 are presented. The estimated accuracy of the procedure is evaluated using computer simulations. The methodology should prove useful in studying how signals from the local neighborhood of a neuron, thought to provide a dominant feedback signal, shape the receptive field properties in V1.

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Skrotzki, Werner, J. Dornbusch, F. Heinicke, and K. Ullemeyer. "Formation of Oblique Shape and Lattice Preferred Orientation in a Quartz Band of a Gneissic Mylonite." Materials Science Forum 157-162 (May 1994): 1481–86. http://dx.doi.org/10.4028/www.scientific.net/msf.157-162.1481.

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McCormack, R., D. P. Dobson, N. P. Walte, N. Miyajima, T. Taniguchi, and I. G. Wood. "The development of shape- and crystallographic-preferred orientation in CaPtO3 post-perovskite deformed in pure shear." American Mineralogist 96, no. 10 (September 20, 2011): 1630–35. http://dx.doi.org/10.2138/am.2011.3881.

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Di Chiara, Anita, Antony Morris, Mark W. Anderson, Luca Menegon, and Alain Tremblay. "Magnetic anisotropy reveals Acadian transpressional fabrics in an Appalachian ophiolite (Thetford Mines, Canada)." Geophysical Journal International 222, no. 2 (April 30, 2020): 1034–45. http://dx.doi.org/10.1093/gji/ggaa173.

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SUMMARY Magnetic anisotropy has proved effective in characterizing primary, spreading-related magmatic fabrics in Mesozoic (Tethyan) ophiolites, for example in documenting lower oceanic crustal flow. The potential for preservation of primary magnetic fabrics has not been tested, however, in older Palaeozoic ophiolites, where anisotropy may record regional strain during polyphase deformation. Here, we present anisotropy of magnetic susceptibility results from the Ordovician Thetford Mines ophiolite (Canada) that experienced two major phases of post-accretion deformation, during the Taconian and Acadian orogenic events. Magnetic fabrics consistent with modal layering in gabbros are observed at one locality, suggesting that primary fabrics may survive deformation locally in low strain zones. However, at remaining sites rocks with different magmatic origins have consistent magnetic fabrics, reflecting structurally controlled shape preferred orientations of iron-rich phases. Subhorizontal NW-SE-oriented minimum principal susceptibility axes correlate with poles to cleavage observed in overlying post-obduction, pre-Acadian sedimentary formations, indicating that the magnetic foliation in the ophiolite formed during regional NW-SE Acadian shortening. Maximum principal susceptibility axes plunging steeply to the NE are orthogonal to the orientation of regional Acadian fold axes, and are consistent with subvertical tectonic stretching. This magnetic lineation is parallel to the shape preferred orientation of secondary amphibole crystals and is interpreted to reflect grain growth during Acadian dextral transpression. This structural style has been widely reported along the Appalachian orogen, but the magnetic fabric data presented here provide the first evidence for transpression recorded in an Appalachian ophiolite.

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Matthies, S., J. Pehl, H. R. Wenk, L. Lutterotti, and S. C. Vogel. "Quantitative texture analysis with the HIPPO neutron TOF diffractometer." Journal of Applied Crystallography 38, no. 3 (May 13, 2005): 462–75. http://dx.doi.org/10.1107/s0021889805006187.

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One of the design goals of the neutron time-of-flight (TOF) diffractometer HIPPO (High Pressure–Preferred Orientation) at LANSCE (Los Alamos Neutron Science Center) was efficient quantitative texture analysis. In this paper, the effects of the HIPPO detector geometry and layout on texture analysis, particularly the shape and dimensions of the detector panels, are investigated in detail. An equal-channel angular-pressed (ECAP) aluminium sample with a strong texture was used to determine the methodological limitations of various methods of quantitative texture analysis. Several algorithms for extracting the orientation distribution function (ODF) from the TOF spectra are compared: discrete orientations at arbitrary positions, harmonic methods in Rietveld codes (MAUD and GSAS) and discrete methods in MAUD. Because of the detector geometry, the sharpest texture peaks that can be represented are 12–15° in width, resulting in an optimal texture resolution of 25–30°. Due to the limited resolution and incomplete pole-figure coverage, harmonic expansions beyond L = 12 (where L is the maximum degree of the harmonic expansion) introduce subsidiary oscillations, which are consistently identified as artifacts. Only discrete methods provide a quantitative representation of the texture. Harmonic methods are adequate for a qualitative description of the main texture component. The results of the analysis establish HIPPO as an efficient instrument to determine preferred orientations in relatively short measuring times.

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Soler, J. D., P. A. R. Ade, F. E. Angilè, P. Ashton, S. J. Benton, M. J. Devlin, B. Dober, et al. "The relation between the column density structures and the magnetic field orientation in the Vela C molecular complex." Astronomy & Astrophysics 603 (July 2017): A64. http://dx.doi.org/10.1051/0004-6361/201730608.

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We statistically evaluated the relative orientation between gas column density structures, inferred from Herschel submillimetre observations, and the magnetic field projected on the plane of sky, inferred from polarized thermal emission of Galactic dust observed by the Balloon-borne Large-Aperture Submillimetre Telescope for Polarimetry (BLASTPol) at 250, 350, and 500 μm, towards the Vela C molecular complex. First, we find very good agreement between the polarization orientations in the three wavelength-bands, suggesting that, at the considered common angular resolution of 3.́0 that corresponds to a physical scale of approximately 0.61 pc, the inferred magnetic field orientation is not significantly affected by temperature or dust grain alignment effects. Second, we find that the relative orientation between gas column density structures and the magnetic field changes progressively with increasing gas column density, from mostly parallel or having no preferred orientation at low column densities to mostly perpendicular at the highest column densities. This observation is in agreement with previous studies by the Planck collaboration towards more nearby molecular clouds. Finally, we find a correspondencebetween (a) the trends in relative orientation between the column density structures and the projected magnetic field; and (b) the shape of the column density probability distribution functions (PDFs). In the sub-regions of Vela C dominated by one clear filamentary structure, or “ridges”, where the high-column density tails of the PDFs are flatter, we find a sharp transition from preferentially parallel or having no preferred relative orientation at low column densities to preferentially perpendicular at highest column densities. In the sub-regions of Vela C dominated by several filamentary structures with multiple orientations, or “nests”, where the maximum values of the column density are smaller than in the ridge-like sub-regions and the high-column density tails of the PDFs are steeper, such a transition is also present, but it is clearly less sharp than in the ridge-like sub-regions. Both of these results suggest that the magnetic field is dynamically important for the formation of density structures in this region.

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Ren, Qi, and Kyle T. Spikes. "Modeling the effects of microscale fabric complexity on the anisotropy of the Eagle Ford Shale." Interpretation 4, no. 2 (May 1, 2016): SE17—SE29. http://dx.doi.org/10.1190/int-2015-0120.1.

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Microscale fabric influences the elastic properties of rock formations. The complexity of the microscale fabric of shale results from composition, platy clay minerals, kerogen, and their preferred orientation patterns. This microscale fabric is also the likely cause of the elastic anisotropy of the rock. In this paper, we have developed a comprehensive three-step rock-physics approach to model the anisotropic elastic properties of the Upper Eagle Ford Shale. We started with anisotropic differential effective medium modeling, followed by an orientation correction, and then a pressure adjustment. This method accounts for the microscale fabric of the rock in terms of the complex composition, shape, and alignment of clay minerals, pore space, and kerogen. In addition, we accounted for different pressure-dependent behaviors of P- and S-waves. Our modeling provides anisotropic stiffnesses and pseudologs of anisotropy parameters. The modeling results match the log measurements relatively well. The clay content, kerogen content, and porosity decreased the rock stiffness. The anisotropy increases with kerogen content, but the influence of clay content was more complex. Comparing the anisotropy parameter pseudologs with clay content shows that clay content increases anisotropy at small concentrations; however, the anisotropy stays constant, or even slightly decreases, as the clay content continues to increase. This result suggests that the preferred orientation of clay clusters is preserved at low clay concentration but vanishes at high clay concentration. This method could also be applied to other shales with carefully chosen parameters to model anisotropic elastic properties.

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Ishii, Kazuhiko, and Takashi Sawaguchi. "Lattice- and shape-preferred orientation of orthopyroxene porphyroclasts in peridotites: an application of two-dimensional numerical modeling." Journal of Structural Geology 24, no. 3 (March 2002): 517–30. http://dx.doi.org/10.1016/s0191-8141(01)00078-5.

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Botero García, Manuela, Sara Paulina Marín López, and Javier Vinasco Vallejo. "Shape Preferred Orientation (SPO) methodology for oriented hand specimens of rock and outcrops through digital image processing." Boletín de Ciencias de la Tierra, no. 38 (July 1, 2015): 5–13. http://dx.doi.org/10.15446/rbct.n38.44724.

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The shape-preferred orientation (SPO) is a technique, which allows the study of the fabric of deformed rocks and understanding its dominant deformational style and partitioning. This work presents SPO results and methodological aspects for one hand specimen of rock and a high-resolution composed image of an outcrop through digital image processing. The technique involves imaging of three semi-orthogonal oriented sections for digital processing and subsequent implementation in structural software. The image processing consists of digital separation of a phase of interest, i.e. defining the deformational fabric. The processed images are then implemented in the SPO2003® software for acquisition of sectional ellipses and finally implemented in the Ellipsoid2003® software to obtain the characteristic ellipsoid of deformational fabric. For outcrops, due to the difficulty to finding three appropriate sections for photography, it was only obtained a sectional ellipse, characteristic of the rock fabric based on contrasting deformed quartz segregates in mylonitic schists.

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Renjith, A. R., Manish A. Mamtani, V. Abhijith, and Virendra Rana. "Magnetic Anisotropy vs. Shape Preferred Orientation in Quartzites with Negative Susceptibility — Implications for Analysing Strain Intensity Variations." Journal of the Geological Society of India 94, no. 1 (July 2019): 23–34. http://dx.doi.org/10.1007/s12594-019-1262-1.

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Rosińska, Katarzyna, and Karolina Adamska. "Biometrics Variation and Directional Preferences of Immature Robins (Erithacus rubecula) Caught in Northern Italy during Autumn Migration in 2005." Ring 29, no. 1-2 (January 1, 2007): 107–20. http://dx.doi.org/10.2478/v10050-008-0038-6.

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Biometrics Variation and Directional Preferences of Immature Robins (Erithacus rubecula) Caught in Northern Italy during Autumn Migration in 2005 Inter-seasonal changes of biometry and preferred migration directions of Robins were studied according to data collected during autumn migration in northern Italy at the Arosio Bird Observatory (45°43'N, 9°12'E). Altogether 598 immature Robins were caught and 187 orientation tests were performed. Wing, tail and tarsus length, wing shape and weight were analysed in subsequent five migration waves distinguished according to migration dynamics. General pattern of migration as well as graphs with distribution of preferred directions in subsequent waves were prepared. In the case of tail length and weight their average values in subsequent waves were significantly different. Decrease of wing length was noted along the season. On the contrary, increasing trend was observed in the case of tail length and wing shape. Results of orientation tests showed that SSE direction was predominant (34%). SW direction was not clearly marked and its percentage was 23%. Distribution of directions slightly changed in subsequent migration waves. Noted results suggest passage of Robins heading to the Mediterranean basin and Apennine winter quarters. Obtained inter-seasonal changes of biometry and preferred directions can be an effect of differences in migration time between this groups or gradual inflow of more northern populations what the authors discuss here.

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Garg, Anupam K., Peichao Li, Mohammad S. Rashid, and Edward M. Callaway. "Color and orientation are jointly coded and spatially organized in primate primary visual cortex." Science 364, no. 6447 (June 27, 2019): 1275–79. http://dx.doi.org/10.1126/science.aaw5868.

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Previous studies support the textbook model that shape and color are extracted by distinct neurons in primate primary visual cortex (V1). However, rigorous testing of this model requires sampling a larger stimulus space than previously possible. We used stable GCaMP6f expression and two-photon calcium imaging to probe a very large spatial and chromatic visual stimulus space and map functional microarchitecture of thousands of neurons with single-cell resolution. Notable proportions of V1 neurons strongly preferred equiluminant color over achromatic stimuli and were also orientation selective, indicating that orientation and color in V1 are mutually processed by overlapping circuits. Single neurons could precisely and unambiguously code for both color and orientation. Further analyses revealed systematic spatial relationships between color tuning, orientation selectivity, and cytochrome oxidase histology.

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Natale, C. F., J. Lafaurie-Janvore, M. Ventre, A. Babataheri, and A. I. Barakat. "Focal adhesion clustering drives endothelial cell morphology on patterned surfaces." Journal of The Royal Society Interface 16, no. 158 (September 2019): 20190263. http://dx.doi.org/10.1098/rsif.2019.0263.

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In many cell types, shape and function are intertwined. In vivo, vascular endothelial cells (ECs) are typically elongated and aligned in the direction of blood flow; however, near branches and bifurcations where atherosclerosis develops, ECs are often cuboidal and have no preferred orientation. Thus, understanding the factors that regulate EC shape and alignment is important. In vitro , EC morphology and orientation are exquisitely sensitive to the composition and topography of the substrate on which the cells are cultured; however, the underlying mechanisms remain poorly understood. Different strategies of substrate patterning for regulating EC shape and orientation have been reported including adhesive motifs on planar surfaces and micro- or nano-scale gratings that provide substrate topography. Here, we explore how ECs perceive planar bio-adhesive versus microgrooved topographic surfaces having identical feature dimensions. We show that while the two types of patterned surfaces are equally effective in guiding and directing EC orientation, the cells are considerably more elongated on the planar patterned surfaces than on the microgrooved surfaces. We also demonstrate that the key factor that regulates cellular morphology is focal adhesion clustering which subsequently drives cytoskeletal organization. The present results promise to inform design strategies of novel surfaces for the improved performance of implantable cardiovascular devices.

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Siegesmund, S., A. Vollbrecht, K. Ullemeyer, and R. Sobott. "Anwendung der geologischen Gefügekunde zur Charakterisierung natürlicher Werksteine - Fallbeispiel: Kauffunger Marmor / Application of geological fabric analyses for the characterization of natural building stones. - Case study: Kauffung marble." Restoration of Buildings and Monuments 3, no. 3 (June 1, 1997): 269–92. http://dx.doi.org/10.1515/rbm-1997-5182.

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Abstract In geology, methods of fabric analyses are largely applied in order to reconstruct the rock-forming processes and define the environments in which they formed. Often, rocks are characterized by polyphase imprints, which occured over a long time span under varying conditions (pressure, temperature, chemical environmentj. In these cases, the final fabrics are usually rather complex. The Kauffung marble is used as an example to demonstrate, how the methods of geological fabric analyses can be applied to the characterization of natural building stones. A correlation with petrophysical analyses reveals that the most important fabric parameters are crystallographic-preferred orientation (texture), the shape-preferred orientation and the microcrack populations, which are usually responsible for a distinct anisotropy. They mainly control the directional dependence of the material properties. These anisotropic properties should be considered during the cutting and later use of natural building stones.

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Journal articles on the topic 'Shape preferred orientation'

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