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Size-strain separation in diffraction line profile analysis.

ABSTRACT: Separation of size and strain effects on diffraction line profiles has been studied in a round robin involving laboratory instruments and synchrotron radiation beamlines operating with different radiation, optics, detectors and experimental configurations. The studied sample, an extensively ball milled iron alloy powder, provides an ideal test case, as domain size broadening and strain broadening are of comparable size. The high energy available at some synchrotron radiation beamlines provides the best conditions for an accurate analysis of the line profiles, as the size-strain separation clearly benefits from a large number of Bragg peaks in the pattern; high counts, reliable intensity values in low-absorption conditions, smooth background and data collection at different temperatures also support the possibility to include diffuse scattering in the analysis, for the most reliable assessment of the line broadening effect. However, results of the round robin show that good quality information on domain size distribution and microstrain can also be obtained using standard laboratory equipment, even when patterns include relatively few Bragg peaks, provided that the data are of good quality in terms of high counts and low and smooth background.

SUBMITTER: Scardi P

PROVIDER: S-EPMC5988009 | biostudies-literature | 2018 Jun

REPOSITORIES: biostudies-literature

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Size-strain separation in diffraction line profile analysis.

Scardi P P Ermrich M M Fitch A A Huang E-Wen EW Jardin R R Kuzel R R Leineweber A A Mendoza Cuevas A A Misture S T ST Rebuffi L L Schimpf Christian C

Journal of applied crystallography 20180529 Pt 3

Separation of size and strain effects on diffraction line profiles has been studied in a round robin involving laboratory instruments and synchrotron radiation beamlines operating with different radiation, optics, detectors and experimental configurations. The studied sample, an extensively ball milled iron alloy powder, provides an ideal test case, as domain size broadening and strain broadening are of comparable size. The high energy available at some synchrotron radiation beamlines provides t ...[more]

PMID: 29896061

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Project description:Sedimentation has been a standard methodology for particle size analysis since the early 1900s. In recent years laser diffraction is beginning to replace sedimentation as the prefered technique in some industries, such as marine sediment analysis. However, for the particle size analysis of soils, which have a diverse range of both particle size and shape, laser diffraction still requires evaluation of its reliability. In this study, the sedimentation based sieve plummet balance method and the laser diffraction method were used to measure the particle size distribution of 22 soil samples representing four contrasting Australian Soil Orders. Initially, a precise wet riffling methodology was developed capable of obtaining representative samples within the recommended obscuration range for laser diffraction. It was found that repeatable results were obtained even if measurements were made at the extreme ends of the manufacturer's recommended obscuration range. Results from statistical analysis suggested that the use of sample pretreatment to remove soil organic carbon (and possible traces of calcium-carbonate content) made minor differences to the laser diffraction particle size distributions compared to no pretreatment. These differences were found to be marginally statistically significant in the Podosol topsoil and Vertosol subsoil. There are well known reasons why sedimentation methods may be considered to 'overestimate' plate-like clay particles, while laser diffraction will 'underestimate' the proportion of clay particles. In this study we used Lin's concordance correlation coefficient to determine the equivalence of laser diffraction and sieve plummet balance results. The results suggested that the laser diffraction equivalent thresholds corresponding to the sieve plummet balance cumulative particle sizes of < 2 μm, < 20 μm, and < 200 μm, were < 9 μm, < 26 μm, < 275 μm respectively. The many advantages of laser diffraction for soil particle size analysis, and the empirical results of this study, suggest that deployment of laser diffraction as a standard test procedure can provide reliable results, provided consistent sample preparation is used.

Project description:PurposeAluminum-based adjuvants including aluminum phosphate (AlPO4) are commonly used in many human vaccines to enhance immune response. The interaction between the antigen and adjuvant, including the physical adsorption of antigen, may play a role in vaccine immunogenicity and is a useful marker of vaccine product quality and consistency. Thus, it is important to study the physicochemical properties of AlPO4, such as particle size and chemical composition. Control of the vaccine adjuvant throughout the manufacturing process, including raw materials and the intermediate and final product stages, can be effectively achieved through monitoring of such key product attributes to help ensure product quality.MethodsThis study focuses on the compositional analysis of AlPO4 adjuvant at the intermediate and final manufacturing stages using the off-line methods Fourier-Transform Infrared (FTIR) and Raman spectroscopy, X-ray Photoelectron Spectroscopy (XPS), and the in-line method Attenuated Total Reflectance (ATR). Particle size distribution of AlPO4 was measured off-line using Laser diffraction (LD) and in-line using Focused Beam Reflectance Measurement (FBRM®).ResultsThere was no observable difference in size distribution between the intermediate and final stage AlPO4 by off-line and in-line analysis, in both small- or large-scale production samples. Consistent peak shifts were observed in off-line and in-line infrared (IR) spectroscopy as well as off-line XPS for both small- and large-scale AlPO4 manufacturing runs. Additionally, IR spectroscopy and FBRM® for size distribution were used as in-line process analytical technology (PAT) to monitor reaction progress in real-time during small-scale AlPO4 manufacturing from raw materials. The small-scale adsorption process of a model protein antigen (Tetanus toxoid) to AlPO4 adjuvant was also monitored by in-line ReactIR probe.ConclusionThis study demonstrated that in-line PAT can be used to monitor particle size and chemical composition for the various stages of adjuvant manufacturing from raw materials through intermediate to final adjuvant product stage. Similar approaches can be utilized to help assess lot-to-lot consistency during adjuvant manufacturing and vaccine product development. Moreover, the use of in-line PAT is highly conductive to advanced manufacturing strategies such as real-time product release testing and automated processes of the future.

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Size-strain separation in diffraction line profile analysis.

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Size-strain separation in diffraction line profile analysis.

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