On the Need for Users of the Powder Diffraction File to Update Regularly

1987 ◽  
Vol 2 (2) ◽  
pp. 84-87 ◽  
Author(s):  
Ron Jenkins ◽  
Mark Holomany ◽  
Winnie Wong-Ng
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Review Process ◽  
Quality Of Data ◽  
Powder Diffraction File ◽  
Editorial Review

AbstractThe International Centre for Diffraction Data has an ongoing program to ensure the quality of data in the Powder Diffraction File (PDF) reflects current requirements of the powder diffraction community. Annual updates are made available, comprising of around 1800 new patterns and 200 replacement patterns, but current statistics indicate that only about 20% of users of the PDF take advantage of these updates. This paper reviews changes which have been inplemented in the editorial review process to continuously monitor and review pattern quality and gives examples of better data which have resulted from these changes.

scholarly journals Data Validation and Structural Classifications in Powder Diffraction File

2014 ◽  
Vol 70 (a1) ◽  
pp. C1702-C1702
Author(s):  
Soorya Kabekkodu
Keyword(s):  
Crystal Structures ◽  
Powder Diffraction ◽  
Pattern Search ◽  
Published Data ◽  
Powder Diffraction File ◽  
Recent Developments ◽  
Diffraction Patterns ◽  
Quality Mark ◽  
Editorial Review

The new Powder Diffraction File™, housing more than 760,000 diffraction patterns and 200,000 crystal structures, has a wealth of information that a materials scientist can take advantage of in various ways, from materials identification, characterization to design. Various structural and chemical classifications implemented in the database will be presented in detail. These classifications are important in data mining studies and optimizing pattern search/match methods. While using any database in materials characterization, it is important to know the quality of the crystal structure or diffraction pattern found in the database. With varying quality of published data in the literature, database editorial review processes had to adopt rigorous data evaluation methods to classify data based on its quality. Every entry in the Powder Diffraction File™ has a quality mark and editorial comments describing the error and the correction. Results of the analysis of the quality of the crystal structures (~500,000) published over the years will be discussed along with the most common errors found. The recent developments in Powder Diffraction File will be presented.

Reference materials for the study of polymorphism and crystallinity in cellulosics

2013 ◽  
Vol 28 (1) ◽  
pp. 18-31 ◽  
Author(s):  
T. G. Fawcett ◽  
C. E. Crowder ◽  
S. N. Kabekkodu ◽  
F. Needham ◽  
J. A. Kaduk ◽  
...  
Keyword(s):  
Powder Diffraction ◽  
Reference Materials ◽  
Reference Data ◽  
Powder Diffraction File ◽  
Material Identification ◽  
Cellulosic Materials ◽  
Chemical Substitution

Eighty specimens of cellulosic materials were analyzed over a period of several years to study the diffraction characteristics resulting from polymorphism, crystallinity, and chemical substitution. The aim of the study was to produce and verify the quality of reference data useful for the diffraction analyses of cellulosic materials. These reference data can be used for material identification, polymorphism, and crystallinity measurements. Overall 13 new references have been characterized for publication in the Powder Diffraction File (PDF) and several others are in the process of publication.

The quality of internet information on psychosis treatment for Australian people (Preprint)

2021 ◽  
Author(s):  
Kay Wilhelm ◽  
Tonelle Handley ◽  
Catherine McHugh McHugh ◽  
David Lowenstein ◽  
Kristy Arrold
Keyword(s):  
Review Process ◽  
Substantial Improvement ◽  
Website Quality ◽  
Related Information ◽  
Internet Information ◽  
Editorial Review ◽  
Assess Quality ◽  
Available Information ◽  
Over Time

BACKGROUND The internet is increasingly seen as an important source of health information for consumers and their families. Accessing information related to their illness and treatment enables consumers to more confidently discuss their health and treatments with their doctors, but the abundance of readily available information also means can be confusing in terms of how reliable the information to enable consumers, families and clinicians to participate in the decision-making process of their care. OBJECTIVE The current study aimed to rate the quality of websites with psychosis-related information (using a validated instrument (DISCERN) and purpose-developed Psychosis Website Quality Checklist (PWQC) to assess quality over time and aid professionals in directing consumers to the best available information. METHODS Entering search terms ‘psychotic’, ‘psychosis’, ‘schizophrenia’, ‘delusion’, ‘hallucination’ into the search engine Google (www.google.com.au) provided 25 websites evaluated by DISCERN and PWQC at two time points, January-March 2014, and January-March 2018, by three diverse health professionals. RESULTS Only the six highest ranked achieved DISCERN scores indicating “good” quality. The overall mean scores of websites were 43.96 (SD=12.08) indicating “fair” quality. PWQC ratings were high on “availability and usability” but poor on “credibility,” “currency,” and “breadth and accuracy”, with no substantial improvement quality over time. Having an editorial/ review process (56% of websites) was significantly associated with higher quality scores on both scales. CONCLUSIONS The quality of available information was ‘fair’ and had not significantly improved over time. While higher-quality websites exist, there is no easy way to assess this on face value. Having a readily identifiable editorial/review process was one indicator of website quality. CLINICALTRIAL Not applicable

Advances in the Computer Indexing of Powder Patterns

1979 ◽  
Vol 23 ◽  
pp. 295-303
Author(s):  
Gordon S. Smith
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Unit Cell ◽  
Computer Assisted ◽  
Powder Diffraction Data ◽  
Quality Of Data ◽  
Small Unit ◽  
Data Set ◽  
Computer Data ◽  
Crystal System

AbstractIndexing of powder-diffraction patterns by computer techniques has advanced to the state that it is now often possible to determine unit-cell dimensions and crystal system for an unknown material solely from its powder-diffraction data. This indexing is fully automated, proceeding directly from positions of observed diffraction lines as input, with decision-making steps being made by a computer. Ease of indexing depends on quality of data (accuracy and completeness), volume of the unit cell, and symmetry of the crystal system. In general, a powder pattern of a triclinic compound with a large unit cell requires a more accurate and complete data-set for successful indexing than does a cubic material having a small unit cell. Fortunately, data from a well-aligned diffractometer or Guinier camera ordinarily suffices for computer indexing. Because of systematic errors in the low-lying diffraction lines, data from the Debye-Scherrer technique usually are not adequate for computer indexing (except for the simpler cases). A brief review of the strategies/algorithms of some of the computer indexing codes now available is given. Criteria for assessing the reliability of a particular computer- assisted indexing are discussed. Finally, attention is directed toward future developments such as by automating the collection of powder- diffraction data, analyzing data by computer data processing, and increasing the speed and reliability of computer indexing.

On racemic and L-malates: a comparison of their crystal structures

2004 ◽  
Vol 219 (2) ◽  
Author(s):  
Michel Fleck ◽  
Ekkehart Tillmanns ◽  
Ladislav Bohatý ◽  
Peter Held
Keyword(s):  
Single Crystal ◽  
Crystal Structures ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Monoclinic Space Group ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
Powder Diffraction File ◽  
Space Group ◽  
X Ray

AbstractThe crystal structures of eight different L-malates have been determined and refined from single-crystal X-ray diffraction data. The compounds are the monoclinic (space groupIn addition, for all the compounds, powder diffraction data were collected, analysed and submitted to the powder diffraction file (PDF).

Upgrading Sulfide Mineral Patterns for the ICDD Powder Diffraction File

1994 ◽  
Vol 38 ◽  
pp. 107-115
Author(s):  
G. J. McCarthy ◽  
D. G. Grier ◽  
P. Bayliss
Keyword(s):  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Essential Role ◽  
Experimental Methods ◽  
Sulfide Mineral ◽  
Powder Diffraction File ◽  
Mineral Powder

Abstract The majority of sulfide mineral patterns in the International Centre for Diffraction Data Mineral Powder Diffraction File have historically been of low quality (e.g., FN < 10 and qualitative intensities). A five-year study has resulted in upgrading approximately 20% of the poorer quality patterns and will triple the number of “star quality” patterns. This paper describes the experimental methods used to obtain these upgraded patterns. The essential role of diffraction pattern calculations and diffractogram simulations is stressed.

Powder X-Ray Diffraction Data of Florencite-(Nd)

1986 ◽  
Vol 1 (4) ◽  
pp. 330-330 ◽  
Author(s):  
Joan Fitzpatrick
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Microscopic Examination ◽  
Spectrographic Analysis ◽  
X Ray Diffraction ◽  
Powder Diffraction File ◽  
X Ray ◽  
Fracture Surfaces ◽  
Franciscan Complex ◽  
Marin County

Florencite-(Nd) [(Nd,Ce)Al3(PO4)2(OH)6], was first described by Milton and Bastron (1971) from fracture surfaces in weathered cherts of the Franciscan Complex, south of Sausalito in Marin County, California. Florencite-(Nd) occurred there as a moderate-brown pulverulent earthy material; individual crystals were not discernible under microscopic examination. A semi-quantitative spectrographic analysis showed the presence of Nd (3 wt. %) and Ce (0.5 wt. %). No powder data for florencite-(Nd) exists in the current powder diffraction file.

New X-ray powder diffraction data for two triborates CsB3O5(CBO) and TlB3O5(TBO)

1999 ◽  
Vol 14 (3) ◽  
pp. 234-236 ◽  
Author(s):  
M. Touboul ◽  
N. Pénin ◽  
L. Seguin
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Powder Diffraction Data ◽  
Powder Diffraction File ◽  
Space Group ◽  
X Ray ◽  
Figures Of Merit ◽  
Diffraction Patterns ◽  
Better Than

Precise X-ray powder diffraction patterns of two isostructural triborates, CsB3O5(CBO) and TlB3O5(TBO), have been collected on a D5000 diffractometer with a primary monochromated beam (λ CuKα1=1.5406 Å). Refinement of indexed reflections in the space group P212121 led to: a=6.201(1) Å, b=8.514(2) Å, c=9.176(2) Å, Z=4, Dx=3.363 for CBO and a=5.2156(4) Å, b=8.2659(6) Å, c=10.2240(9) Å, Z=4, Dx=4.773 for TBO. The Smith–Snyder figures of merit are F30=53.0 (0.0101, 56) for CBO and F30=112.9 (0.0074, 36) for TBO. These values are much better than the previous ones published in Powder Diffraction File.

Crystal structure of citalopram hydrobromide, C20H22FN2OBr

2016 ◽  
Vol 31 (3) ◽  
pp. 176-184
Author(s):  
James A. Kaduk ◽  
Kai Zhong ◽  
Amy M. Gindhart ◽  
Thomas N. Blanton
Keyword(s):  
Crystal Structure ◽  
Density Functional Theory ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Density Functional ◽  
Powder Diffraction Data ◽  
Powder Diffraction File ◽  
Functional Theory ◽  
X Ray ◽  
Van Der Waals Attraction

The crystal structure of citalopram hydrobromide has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional theory techniques. Citalopram hydrobromide crystallizes in space group P21/c (#14) with a = 10.766 45(6), b = 33.070 86(16), c = 10.892 85(5) Å, β = 90.8518(3)°, V = 3878.03(4) Å3, and Z = 8. N–H⋯Br hydrogen bonds are important to the structure, but the crystal energy is dominated by van der Waals attraction. The powder pattern was submitted to International Centre for Diffraction Data for inclusion in the Powder Diffraction File™.

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