A Review of the Terms Agglomerate and Aggregate with a Recommendation for Nomenclature Used in Powder and Particle Characterization

Nichols, Gary; Byard, Stephen J.; Bloxham, Mark; Botterill, Joanne; Dawson, Neil; Dennis, Andrew B.; Diart, Valerie; North, Nigel C.; Sherwood, J. D.

doi:10.1002/jps.10191

Cited by 215 publications

(125 citation statements)

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“…Particles of pharmaceutical organic materials can be very cohesive and electrostatically charged, forming agglomerates of different sizes and structures. If the forces holding the primary particles are weak and more of a physical nature, the particles are said to be in the form of soft agglomerates (84). Strongly bonded, Bbridged^particles are said to form hard agglomerates, which typically originate from the particle formation process, inadequate cleaning or drying.…”

Section: Sampling and Dispersionmentioning

confidence: 99%

Particle Size Analysis in Pharmaceutics: Principles, Methods and Applications

et al. 2006

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Physicochemical and biopharmaceutical properties of drug substances and dosage forms can be highly affected by the particle size, a critical process parameter in pharmaceutical production. The fundamental issue with particle size analysis is the variety of equivalent particle diameters generated by different methods, which is largely ascribable to the particle shape and particle dispersion mechanism involved. Thus, to enable selection of the most appropriate or optimal sizing technique, cross-correlation between different techniques may be required. This review offers an in-depth discussion on particle size analysis pertaining to specific pharmaceutical applications and regulatory aspects, fundamental principles and terminology, instrumentation types, data presentation and interpretation, in-line and process analytical technology. For illustration purposes, special consideration is given to the analysis of aerosols using time-of-flight and cascade impactor measurements, which is supported by a computational analysis conducted for this review.

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Section: Sampling and Dispersionmentioning

confidence: 99%

Particle Size Analysis in Pharmaceutics: Principles, Methods and Applications

et al. 2006

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“…This implies that submicron to several micronsized primary particles were formed after wet planetary ball milling, and then, they tended to agglomerate/aggregate into several to several tens micrometers. From an engineering viewpoint, soft "agglomerated" particles (in ISO 14887:2000 definition 38) ) might be favorable for the powder processing. Figure 2 shows HT-XRD patterns for the MgCO 3 (basic) and TiO 2 mixed powder (Mg:Ti = 1:2 in mole fraction) doped with LiF (0.5 mass % for total starting powders).…”

mentioning

confidence: 99%

Uniformly porous MgTi2O5 with narrow pore-size distribution: in situ processing, microstructure and thermal expansion behavior

Suzuki

Morimoto

2010

J. Ceram. Soc. Japan

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Porous ceramics based on refractory double oxides are promising for light-weight structural components and high-temperature filter materials. In this study, porous MgTi 2 O 5 ceramics with pseudobrookite-type structure have been prepared by in situ processing (viz. reactive sintering). High-temperature XRD revealed the in situ reaction behavior of the mixed powder, and indicated suitable sintering temperatures to obtain single phase MgTi 2 O 5 (²1000°C). Uniformly porous MgTi 2 O 5 ceramics with very narrow pore-size distribution at the diameter of ³1 µm were obtained by the pyrolytic reactive sintering at 10001200°C, where decomposed CO 2 gas from a carbonate source acted as an intrinsic pore forming agent. Thermal expansion behavior of bulk porous MgTi 2 O 5 (porosity: 42%) is also discussed.©2010 The Ceramic Society of Japan. All rights reserved.Key-words : MgTi 2 O 5 , Pseudobrookite, Karrooite, Pore-size distribution, In-situ process, High-temperature XRD, Thermal expansion [Received May 31, 2010; Accepted September 16, 2010] Multiple oxide ceramics with orthorhombic pseudobrookitetype structure (expressed as Me 3 O 5 ) generally have low average (bulk) thermal expansion coefficients among oxides. 1)3) In the pseudobrookite structure, one axis (a-axis in Cmcm notation, or c-axis in Bbmm) has negative or very-small thermal expansion. Such a strong expansion anisotropy induces the formation of microcracks, resulting in the low bulk thermal expansion. 1)Among pseudobrookite oxides, aluminum titanate (Al 2 TiO 5 , AT), has been most eagerly studied as a thermal-shock resistant material.1)11) However, undoped-Al 2 TiO 5 tends to decompose into Al 2 O 3 and TiO 2 at elevated temperatures; 12),13) due to the large distortion of MeO 6 -octahedra, Al 2 TiO 5 phase is metastable below 1200°C. Furthermore, microcracks induced by the strong thermal-expansion anisotropy gradually degrades mechanical properties.MgTi 2 O 5 (karrooite, MT 2 ) also has orthorhombic pseudobrookite-type crystal structure and shows relatively low thermal expansion ( Table 1 31) In this paper, high-temperature X-ray diffractometry for the in situ reaction, effect of sintering temperature on microstructure, and thermal expansion behavior of porous MgTi 2 O 5 are described.Similarly to previously reported UPC-3D (uniformly porous ceramic/composite with three dimension network structure), 33)37) carbonate is used as a starting material; decomposed CO 2 gas, emitted during the one-step pyrolytic reacting sintering, forms very uniform open porous structure. Commercially available MgCO 3 (basic) powder (approx. 3MgCO 3 Mg(OH) 2

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“…Copolymerization carried out with lower concentration of total monomers exhibit formation of larger D v (90) nanoparticles as compared to that of high concentration of total monomers. At high concentrations, dyed copolymer nanoparticles aggregate to form pre-nucleation structures and then lead to agglomeration [31] and thereby coagulum formation. The fluorescent dispersions contain the particles to a lesser extent (Fig.…”

Section: Particle Size Distributionmentioning

confidence: 99%