Alumina trihydrate crystallization. Part 1. Secondary nucleation and growth rate kinetics

1976 ◽  
Vol 54 (3) ◽  
pp. 160-167 ◽  
Author(s):  
A. Halfon ◽  
S. Kaliaguine
Keyword(s):  
Growth Rate ◽  
Nucleation And Growth ◽  
Secondary Nucleation ◽  
Rate Kinetics ◽  
Alumina Trihydrate

Continuous Precipitation of Lead Iodide

1994 ◽  
Vol 59 (7) ◽  
pp. 1503-1510
Author(s):  
Stanislav Žáček ◽  
Jaroslav Nývlt
Keyword(s):  
Growth Rate ◽  
Particle Size ◽  
Crystal Size ◽  
Crystal Growth Rate ◽  
Laboratory Model ◽  
Lead Iodide ◽  
Secondary Nucleation ◽  
Equimolar Ratio ◽  
Continuous Precipitation ◽  
The Mean

Lead iodide was precipitated from aqueous solutions of 0.015 - 0.1 M Pb(NO3)2 and 0.03 - 0.2 M KI in the equimolar ratio using a laboratory model of a stirred continuous crystallizer at 22 °C. After reaching the steady state, the PbI2 crystal size distribution was measured sedimentometrically and the crystallization kinetics was evaluated based on the mean particle size. Both the linear crystal growth rate and the nucleation rate depend on the specific output of the crystallizer. The system crystallization constant either points to a significant effect of secondary nucleation by the mechanism of contact of the crystals with the stirrer blade, or depends on the concentrations of the components added due to the micromixing mechanism.

Phase separation in undercooled molten Pd80Si20: Part I

1999 ◽  
Vol 14 (9) ◽  
pp. 3653-3662 ◽  
Author(s):  
K. L. Lee ◽  
H. W. Kui
Keyword(s):  
Growth Rate ◽  
Phase Separation ◽  
Crystal Growth ◽  
Grain Refinement ◽  
Crystallization Temperature ◽  
Sharp Decrease ◽  
Nucleation And Growth ◽  
Crystal Growth Rate ◽  
Large Undercooling ◽  
Kinetic Crystallization

Three different kinds of morphology are found in undercooled Pd80Si20, and they dominate at different undercooling regimens ΔT, defined as ΔT = T1 – Tk, where T1 is the liquidus of Pd80Si20 and Tk is the kinetic crystallization temperature. In the small undercooling regimen, i.e., for ΔT ≤ 190 K, the microstructures are typically dendritic precipitation with a eutecticlike background. In the intermediate undercooling regimen, i.e., for 190 ≤ ΔT ≤ 220 K, spherical morphologies, which arise from nucleation and growth, are identified. In addition, Pd particles are found throughout an entire undercooled specimen. In the large undercooling regimen, i.e., for ΔT ≥ 220 K, a connected structure composed of two subnetworks is found. A sharp decrease in the dimension of the microstructures occurs from the intermediate to the large undercooling regimen. Although the crystalline phases in the intermediate and the large undercooling regimens are the same, the crystal growth rate is too slow to bring about the occurrence of grain refinement. Combining the morphologies observed in the three undercooling regimens and their crystallization behaviors, we conclude that phase separation takes place in undercooled molten Pd80Si20.

Laser-Assisted Biomimetic Process for Calcium Phosphate Coating on a Hydroxyapatite Ceramic

2012 ◽  
Vol 529-530 ◽  
pp. 217-222 ◽  
Author(s):  
Ayako Oyane ◽  
Ikuko Sakamaki ◽  
Yoshiki Shimizu ◽  
Kenji Kawaguchi ◽  
Yu Sogo ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Nucleation And Growth ◽  
Calcium Phosphate Coating ◽  
Dependent Manner ◽  
Secondary Nucleation ◽  
Hydroxyapatite Ceramic ◽  
Ethylene Vinyl Alcohol ◽  
Coating Technique ◽  
Laser Absorption ◽  
Dental Applications

The present authors recently developed a new calcium phosphate (CaP) coating technique on an ethylene-vinyl alcohol copolymer substrate utilizing a laser-assisted biomimetic (LAB) process. In the present study, the LAB process was applied to a sintered hydroxyapatite (sHA) substrate for CaP coating. The LAB process was carried out by irradiating the sHA substrate immersed in a supersaturated CaP solution with a low-energy Nd-YAG pulsed laser. Within 30 min of irradiation, contiuous CaP layers with different morphologies were successfully formed on the laser-irradiated sHA surface. A submicron cavernous structure of the CaP layer was developed into a micron flake-like structure as the laser power increased from 1 to 3 W. This result suggests that the secondary nucleation and growth of CaP crystals were accelerated by laser irradiation in a power-dependent manner. Laser absorption by the sHA substrate and the resulting increase in ambient temperature locally near the surface should be responsible for the accelerated CaP nucleation and growth. The present CaP coating technique using the LAB process is simple and quick, hence it would be useful in orthopedic and dental applications as an on-demand surface-functionalization method for biomaterials consisting of sHA.

scholarly journals Revisiting Models for Spheroidal Graphite Growth

2018 ◽  
Vol 925 ◽  
pp. 118-124 ◽  
Author(s):  
Mathias Karsten Bjerre ◽  
Mohammed Azeem ◽  
Peter D. Lee ◽  
Jesper Henri Hattel ◽  
Niels Skat Tiedje
Keyword(s):  
Growth Rate ◽  
Cast Iron ◽  
Numerical Model ◽  
Final Stage ◽  
Nucleation And Growth ◽  
Ductile Cast Iron ◽  
Spheroidal Graphite ◽  
Microstructure Formation ◽  
X Ray ◽  
Graphite Growth

Recent experiments resolved nucleation and growth of graphite during solidification of ductile cast iron in 4D using synchrotron X-ray tomography. A numerical model for microstructure formation during solidification is compared with the experiments. Despite very good overall agreement between observations of spheroidal graphite growth and model results, significant deviations exist towards the end of solidification. We use the experimental observations to analyse the relation between graphite growth rate and the state of the particle neighbourhood to pinpoint possible links between growth rate of individual graphite spheres and the overall solidification state. With this insight we revisit existing models for growth of spheroidal graphite and discuss possible modifications in order to correctly describe the critical final stage of solidification.

scholarly journals Graphene stimulates the nucleation and growth rate of NaCl crystals from hypersaline solution via membrane crystallization

2020 ◽  
Vol 6 (6) ◽  
pp. 1723-1736
Author(s):  
Maria Luisa Perrotta ◽  
Francesca Macedonio ◽  
Elena Tocci ◽  
Lidietta Giorno ◽  
Enrico Drioli ◽  
...  
Keyword(s):  
Growth Rate ◽  
Nucleation And Growth ◽  
High Quality ◽  
Hypersaline Water

Advanced graphene engineered membranes designed for sustainable crystallization of high-quality crystals from hypersaline water.

scholarly journals Physiological characteristics of the anaerobic ammonium-oxidizing bacterium ‘Candidatus Brocadia sinica’

Microbiology ◽  
2011 ◽  
Vol 157 (6) ◽  
pp. 1706-1713 ◽  
Author(s):  
Mamoru Oshiki ◽  
Masaki Shimokawa ◽  
Naoki Fujii ◽  
Hisashi Satoh ◽  
Satoshi Okabe
Keyword(s):  
Growth Rate ◽  
Removal Rate ◽  
Nitrite Reduction ◽  
Physiological Characteristics ◽  
Anammox Bacteria ◽  
Ammonium Oxidation ◽  
Phylogenetic Affiliation ◽  
Anammox Activity ◽  
Rate Kinetics ◽  
Kinetics Of

The present study investigated the phylogenetic affiliation and physiological characteristics of bacteria responsible for anaerobic ammonium oxidization (anammox); these bacteria were enriched in an anammox reactor with a nitrogen removal rate of 26.0 kg N m−3 day−1. The anammox bacteria were identified as representing ‘Candidatus Brocadia sinica’ on the basis of phylogenetic analysis of rRNA operon sequences. Physiological characteristics examined were growth rate, kinetics of ammonium oxidation and nitrite reduction, temperature, pH and inhibition of anammox. The maximum specific growth rate (μmax) was 0.0041 h−1, corresponding to a doubling time of 7 days. The half-saturation constants (K s) for ammonium and nitrite of ‘Ca. B. sinica’ were 28±4 and 86±4 µM, respectively, higher than those of ‘Candidatus Brocadia anammoxidans’ and ‘Candidatus Kuenenia stuttgartiensis’. The temperature and pH ranges of anammox activity were 25–45 °C and pH 6.5–8.8, respectively. Anammox activity was inhibited in the presence of nitrite (50 % inhibition at 16 mM), ethanol (91 % at 1 mM) and methanol (86 % at 1 mM). Anammox activities were 80 and 70 % of baseline in the presence of 20 mM phosphorus and 3 % salinity, respectively. The yield of biomass and dissolved organic carbon production in the culture supernatant were 0.062 and 0.005 mol C (mol NH 4 + )−1, respectively. This study compared physiological differences between three anammox bacterial enrichment cultures to provide a better understanding of anammox niche specificity in natural and man-made ecosystems.

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