Crystallographic computing system Jana2006: solution and refinement of twinned structures

2016 ◽  
Vol 231 (10) ◽  
Author(s):  
Václav Petříček ◽  
Michal Dušek ◽  
Jakub Plášil
Keyword(s):  
Data Processing ◽  
Single Crystals ◽  
Structure Analysis ◽  
Computing System ◽  
Modulated Structure ◽  
Magnetic Structures ◽  
The Third ◽  
Modulated Structures ◽  
Diffraction Patterns ◽  
The Relationship

AbstractTwinning is a phenomenon complicating structure analysis of single crystals of standard as well as modulated structures. Jana2006 as a software for advanced structure analysis contains tools for recognition and refinement of twins including most complicated cases of modulated and magnetic structures. In order to efficiently use the tools of Jana2006 related to twinning, we explain the basic terminology and the underlying theory, especially the symmetry of the diffraction patterns affected by twinning. We present typical diffraction patterns of twins and show how twinning can be recognized or detected by various tools and described with twinning matrices. Data processing of twins and ways of how they can be imported to Jana2006 are also discussed. Two examples demonstrate the solution of typical twins: twinning by metric merohedry and twinning by reticular merohedry, followed by the third example demonstrating twinning in a commensurately modulated structure. The relationship between the dimensionality of the structure and twinning is discussed, too.

scholarly journals A non-mathematical introduction to the superspace description of modulated structures

2009 ◽  
Vol 65 (3) ◽  
pp. 249-268 ◽  
Author(s):  
Trixie Wagner ◽  
Andreas Schönleber
Keyword(s):  
Crystal Structure ◽  
Data Processing ◽  
Reciprocal Lattice ◽  
Molecular Compound ◽  
Modulated Structure ◽  
X Ray ◽  
Modulated Structures ◽  
Structure Solution ◽  
Superspace Description ◽  
Complete Process

The X-ray analysis of (6R,7aS)-6-(tert-butyl-dimethylsilanyloxy)-1-hydroxy-2-phenyl-5,6,7,7a-tetrahydropyrrolizin-3-one, C19H27NO3Si, revealed a diffraction pattern which is typical for modulated structures: strong Bragg peaks surrounded by weaker reflections which cannot be indexed with the same three reciprocal lattice vectors that are used to describe the strong peaks. For this class of crystal structures the concept of superspace has been developed which, however, for many crystallographers still constitutes a Gordian Knot. As a possible tool to cut this knot the crystal structure of the above-mentioned tetrahydropyrrolizinone derivative is presented as an illustrative example for handling and describing the modulated structure of a typical pharmaceutical (i.e. molecular) compound. Having established a working knowledge of the concepts and terminology of the superspace approach a concise and detailed description of the complete process of peak indexing, data processing, structure solution and structure interpretation is presented for the incommensurately modulated crystal structure of the above-mentioned compound. The superspace symmetry applied is P21(α0γ)0; the (incommensurate) q vector components at 100 K are α = 0.1422 (2) and γ = 0.3839 (8).

Tem Observance and Analysis of the (000l), l=2n+l, Forbidden Reflections in Synthetic and Biological Hydroxyapatites

1999 ◽  
Vol 599 ◽  
Author(s):  
J. Reyes-Gasga ◽  
M. Reyes-Reyes ◽  
R. García-García
Keyword(s):  
Electron Diffraction ◽  
Tooth Enamel ◽  
Structural Disorder ◽  
Human Tooth ◽  
Double Diffraction ◽  
Modulated Structure ◽  
Human Tooth Enamel ◽  
Modulated Structures ◽  
Diffraction Patterns

AbstractThe systematic appearance of (000l), l=2n+1, forbidden reflections in the electron diffraction patterns of hydroxyapatite, both synthetic and natural (human tooth enamel), is discussed. Structural disorder, double diffraction, and modulated structures and are discussed as possible causes. Structural disorder and modulated structure could be responsible for the rupture of the reported symmetry, in which oxygen and hydrogen perform an important role.

Intergrowth of modulated structures in high Tc Bi-Sr-Ca-Cu-O superconductors

1990 ◽  
Vol 48 (4) ◽  
pp. 76-77
Author(s):  
A.Q. He ◽  
G.W. Qiao ◽  
J. Zhu ◽  
H.Q. Ye
Keyword(s):  
Twin Structure ◽  
Modulated Structure ◽  
High Tc ◽  
One Dimensional ◽  
Lattice Constants ◽  
Superconducting Phases ◽  
Modulated Structures ◽  
Layer Structures

Since the first discovery of high Tc Bi-Sr-Ca-Cu-O superconductor by Maeda et al, many EM works have been done on it. The results show that the superconducting phases have a type of ordered layer structures similar to that in Y-Ba-Cu-O system formulated in Bi2Sr2Can−1CunO2n+4 (n=1,2,3) (simply called 22(n-1) phase) with lattice constants of a=0.358, b=0.382nm but the length of c being different according to the different value of n in the formulate. Unlike the twin structure observed in the Y-Ba-Cu-O system, there is an incommensurate modulated structure in the superconducting phases of Bi system superconductors. Modulated wavelengths of both 1.3 and 2.7 nm have been observed in the 2212 phase. This communication mainly presents the intergrowth of these two kinds of one-dimensional modulated structures in 2212 phase.

Transmission Electron Microscopy study of Bi-based superconducting phases

1990 ◽  
Vol 48 (4) ◽  
pp. 50-51
Author(s):  
J.G. Wen ◽  
K.K. Fung
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Single Crystals ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Space Groups ◽  
Superconducting Phases ◽  
Ceramic Samples ◽  
Transmission Electron ◽  
Modulated Structures

Bi-based superconducting phases have been found to be members of a structural series represented by Bi2Sr2Can−1Cun−1On+4, n=1,2,3, and are referred to as 2201, 2212, 2223 phases. All these phases are incommensurate modulated structures. The super space groups are P2/b, NBbmb 2201, 2212 phases respectively. Pb-doped ceramic samples and single crystals and Y-doped single crystals have been studied by transmission electron microscopy.Modulated structures of all Bi-based superconducting phases are in b-c plane, therefore, it is the best way to determine modulated structure and c parameter in diffraction pattern. FIG. 1,2,3 show diffraction patterns of three kinds of modulations in Pb-doped ceramic samples. Energy dispersive X-ray analysis (EDAX) confirms the presence of Pb in the three modulated structures. Parameters c are 3 0.06, 38.29, 30.24Å, ie 2212, 2223, 2212 phases for FIG. 1,2,3 respectively. Their average space groups are all Bbmb.

Retroaktive Neuverhandlung

2018 ◽  
Vol 63 (1) ◽  
Author(s):  
Daniel Martin Feige
Keyword(s):  
Original Work ◽  
The Other ◽  
Final Part ◽  
Critical Reading ◽  
The Third ◽  
Works Of Art ◽  
The Relationship

Der Beitrag widmet sich der Frage historischer Folgeverhältnisse in der Kunst. Gegenüber dem Gedanken, dass es ein ursprüngliches Werk in der Reihe von Werken gibt, das späteren Werken seinen Sinn gibt, schlägt der Text vor, das Verhältnis umgekehrt zu denken: Im Lichte späterer Werke wird der Sinn früherer Werke neu ausgehandelt. Dazu geht der Text in drei Schritten vor. Im ersten Teil formuliert er unter der Überschrift ›Form‹ in kritischer Abgrenzung zu Danto und Eco mit Adorno den Gedanken, dass Kunstwerke eigensinnig konstituierte Gegenstände sind. Die im Gedanken der Neuverhandlung früherer Werke im Lichte späterer Werke vorausgesetzte Unbestimmtheit des Sinns von Kunstwerken wird im zweiten Teil unter dem Schlagwort ›Zeitlichkeit‹ anhand des Paradigmas der Improvisation erörtert. Der dritte und letzte Teil wendet diese improvisatorische Logik unter dem Label ›Neuaushandlung‹ dann dezidiert auf das Verhältnis von Vorbild und Nachbild an. The article proposes a new understanding of historical succession in the realm of art. In contrast to the idea that there is an original work in the series of works that gives meaning to the works that come later, the text proposes to think it exactly the other way round: in the light of later works, the meanings of earlier works are renegotiated. The text proceeds in three steps to develop this idea. Under the heading ›Form‹ it develops in the first part a critical reading of Danto’s and Eco’s notion of the constitution of the artworks and argues with Adorno that each powerful work develops its own language. In the second part, the vagueness of the meaning of works of art presupposed in the idea of renegotiating earlier works in the light of later works is discussed under the term ›Temporality‹ in terms of the logic of improvisation. The third and final part uses this improvisational logic under the label ›Renegotiation‹ to understand the relationship between model and afterimage in the realm of art.

RECREATION SPECIALIZATION FOR RUNNERS AND EVENT ATTACHMENT

2020 ◽  
Author(s):  
Isao Okayasu ◽  
Chi-Ok Oh ◽  
Duarte B Morais
Keyword(s):  
Practical Implication ◽  
Event Management ◽  
Attitudes And Behaviors ◽  
The Third ◽  
Study Results ◽  
The World ◽  
Recreation Specialization ◽  
And Behaviors ◽  
The Relationship ◽  
Predictive Relationship

Running is one of the most popular activities in the world. Runners’ attitudes and behaviors vary depending on their running style. This study aims to construct different measures of running specialization based on the theory of specialization. This study also tests a runner’s stage of specialization segmentation based on recreation specialization and examines the predictive relationship between a runner’s specialization and event attachment. Three groups of sampling data assess the performance of diverse specialization measures for running in three marathon events. First, two surveys were conducted with marathon participants to assess the performance of diverse specialization measures for runners. Second, the third dataset was used to examine the relationship between a runner’s recreation specialization and event attachment.The study results showed that the 15 measures of specialization showed a good fit to the data. Our research showed how runners’ recreation specialization is connected to their event attachment. In addition, this study suggested event management for subdivisions of runners. Its practical implication is that recreation specialization for running can help us understand event attachment.

scholarly journals Analyzing the Effects of the Kinematic System on the Quality of Holes Drilled in 42CrMo4 + QT Steel

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4046
Author(s):  
Mateusz Bronis ◽  
Edward Miko ◽  
Lukasz Nowakowski
Keyword(s):  
Cutting Speed ◽  
Hole Drilling ◽  
Internal Cooling ◽  
Hole Quality ◽  
The Third ◽  
Kinematic System ◽  
Turning Center ◽  
Dimensional Errors ◽  
The Relationship

This article discusses the relationship between the kinematic system used in drilling and the quality of through-holes. The drilling was done on a CTX Alpha 500 universal turning center using a TiAlN-coated 6.0 mm drill bit with internal cooling, mounted in a driven tool holder. The holes were cut in cylindrical 42CrMo4 + QT steel samples measuring 30 mm in diameter and 30 mm in length. Three types of hole-drilling kinematic systems were considered. The first consisted of a fixed workpiece and a tool performing rotary (primary) and linear motions. In the second system, the workpiece rotated (primary motion) while the tool moved linearly. In the third system, the workpiece and the tool rotated in opposite directions; the tool also moved linearly. The analysis was carried out for four output parameters characterizing the hole quality (i.e., cylindricity, straightness, roundness, and diameter errors). The experiment was designed using the Taguchi approach (orthogonal array). ANOVA multi-factor statistical analysis was used to determine the influence of the input parameters (cutting speed, feed per revolution and type of kinematic system) on the geometrical and dimensional errors of the hole. From the analysis, it is evident that the kinematic system had a significant effect on the hole roundness error.

scholarly journals The Correlation Between Timing of Surgery and the Need for RBC Transfusions in the Geriatric Intertrochanteric Fracture Population

2021 ◽  
Vol 12 ◽  
pp. 215145932199861
Author(s):  
Yun-fa Yang ◽  
Jian-wen Huang ◽  
Xiao-sheng Gao ◽  
Zai-li Liu ◽  
Jian-wei Wang ◽  
...  
Keyword(s):  
Intertrochanteric Fracture ◽  
The Elderly ◽  
Timing Of Surgery ◽  
Intertrochanteric Fractures ◽  
The Third ◽  
Transfusion Requirements ◽  
Surgical Fixation ◽  
Fracture Population ◽  
The Relationship ◽  
Rbc Transfusion

Objective: To identify whether the timing of surgery affects red blood cell (RBC) transfusion requirements in the elderly with intertrochanteric fractures. Methods: We retrospectively studied all patients undergoing surgical fixation of their intertrochanteric fractures in our hospital between January 2009 and December 2018 and analyzed the relationship between the timing of surgery and RBC transfusion. Results: A total of 679 patients were included in this study. The need for RBC transfusion was lower in the patients who underwent surgery within 12 h after admission (timing of surgery <12 h, <12 h group) than those who underwent surgery over 12 h after admission (timing of surgery >12 h, >12 h group) (P = 0.046); lower in the the patients who underwent surgery within 24 h after admission (timing of surgery <24 h, <24 h group) than in those who underwent surgery over 24 h after admission (timing of surgery >24 h, >24 h group) (P = 0.008), and lower in the <24 h group compared to the patients who underwent surgery within 48 h after admission (timing of surgery <48 h, <48 h group) (P = 0.035). Moreover, the need for RBC transfusion was lower in the <24 h group (in the first 24 h from admission to surgery) than in the 24-48 h group (in the second 24 h from admission to surgery) (P = 0.016), and also lower in the <24 h group compared to the 48-72 h group (in the third 24 h from admission to surgery) (P = 0.047). However, there were no differences between the <12 h group and 12-24 h group, between the <12 h group and <24 h group, and between the 12-24 h group and <24 h group, respectively. Conclusion: Timing of surgery within 24 h contributes to the reduction of RBC transfusion in the elderly with intertrochanteric fractures.

Women’s Liberation and the Agrarian Question: Insights from Peasant Movements in India

2021 ◽  
Vol 10 (1) ◽  
pp. 15-40
Author(s):  
Archana Prasad
Keyword(s):  
Social Transformation ◽  
Historical Context ◽  
Class Consciousness ◽  
Land Reforms ◽  
Agrarian Question ◽  
The Third ◽  
Peasant Movements ◽  
Participation Of Women ◽  
The Relationship

This article explores some questions arising from recent debates on patriarchy and capitalism. The focus is on the role of women in communist-led peasant movements in India and the implications of such struggles on the project of women’s emancipation. The first section lays out a framework for discussing the interface between class consciousness and the anti-patriarchal project, whereby patriarchy is located within the structural contradictions arising out of the contestations within the process of accumulation. The second section documents the historical context, focusing on the relationship between land reforms and social transformation in semi-feudal and early capitalist contexts, and analyzes the extent to which communist-led struggles are anti-patriarchal in character. The third section turns to the participation of women in the contemporary struggles of both agricultural workers and peasant movements and underlines the new emerging dialectics between women’s and peasant organizations under a neoliberal state and with deepening agrarian distress.

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