scholarly journals Numerical Frameworks for Laser-Induced Cavitation: Is Interface Supersaturation a Plausible Primary Nucleation Mechanism?

2020 ◽  
Vol 20 (11) ◽  
pp. 7276-7290
Author(s):  
Niklas Hidman ◽  
Gaetano Sardina ◽  
Dario Maggiolo ◽  
Henrik Ström ◽  
Srdjan Sasic
Keyword(s):  
Nucleation Mechanism ◽  
Primary Nucleation

scholarly journals Hot Deformation Behavior and Microstructure Evolution of Fe–5Mn–3Al–0.1C High-Strength Lightweight Steel for Automobiles

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2478
Author(s):  
Guangming Liu ◽  
Jinbin Wang ◽  
Yafeng Ji ◽  
Runyuan Hao ◽  
Huaying Li ◽  
...  
Keyword(s):  
Dynamic Recrystallization ◽  
Microstructure Evolution ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Flow Behavior ◽  
Nucleation Mechanism ◽  
Hot Deformation Behavior ◽  
Deformation Parameters ◽  
Primary Nucleation ◽  
Δ Ferrite

The hot deformation behavior of a newly designed Fe–5Mn–3Al–0.1C (wt.%) medium manganese steel was investigated using hot compression tests in the temperature range of 900 to 1150 °C, at constant strain rates of 0.1, 1, 2.5, 5, 10, and 20 s−1. A detailed analysis of the hot deformation parameters, focusing on the flow behavior, hot processing map, dynamic recrystallization (DRX) critical stress, and nucleation mechanism, was undertaken to understand the hot rolling process of the newly designed steel. The flow behavior is sensitive to deformation parameters, and the Zener–Hollomon parameter was coupled with the temperature and strain rate. Three-dimensional processing maps were developed considering the effect of strain and were used to determine safe and unsafe deformation conditions in association with the microstructural evolution. In the deformation condition, the microstructure of the steel consisted of δ-ferrite and austenite; in addition, there was a formation of DRX grains within the δ-ferrite grains and austenite grains during the hot compression test. The microstructure evolution and two types of DRX nucleation mechanisms were identified; it was observed that discontinuous dynamic recrystallization (DDRX) is the primary nucleation mechanism of austenite, while continuous dynamic recrystallization (CDRX) is the primary nucleation mechanism of δ-ferrite. The steel possesses unfavorable toughness at the deformation temperature of 900 °C, which is mainly due to the presence of coarse κ-carbides along grain boundaries, as well as the lower strengthening effect of grain boundaries. This study identified a relatively ideal hot processing region for the steel. Further exploration of hot roll tests will follow in the future.

scholarly journals Poly(butylene succinate-co-butylene acetylenedicarboxylate): Copolyester with Novel Nucleation Behavior

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 365
Author(s):  
Yi Li ◽  
Guoyong Huang ◽  
Cong Chen ◽  
Xue-Wei Wei ◽  
Xi Dong ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Specific Interaction ◽  
Crystallization Rate ◽  
Amorphous Region ◽  
Nucleation Mechanism ◽  
Crystal Modification ◽  
Butylene Succinate ◽  
Nucleation Behavior ◽  
Primary Nucleation ◽  
New Type

Big spherulite structure and high crystallinity are the two main drawbacks of poly(butylene succinate) (PBS) and hinder its application. In this work, a new type of copolyester poly(butylene succinate-co-butylene acetylenedicarboxylate) (PBSAD) is synthesized. With the incorporation of acetylenedicarboxylate (AD) units into PBS chains, the crystallization temperature and crystallinity are depressed by excluding AD units to the amorphous region. In contrast, the primary nucleation capability is significantly strengthened, without changing the crystal modification or crystallization kinetics, leading to the recovery of total crystallization rate of PBSAD under the same supercooling condition. The existence of specific interaction among AD units is found to be crucial. Although it is too weak to contribute to the melt memory effect at elevated temperature, the interaction continuously strengthens as the temperature falls down, and the heterogeneous aggregation of AD units keeps growing. When the aggregating process reaches a certain extent, it will induce the formation of a significant amount of crystal nuclei. The unveiled nucleation mechanism helps to design PBS copolymer with good performance.

Transmission Electron Microscopy characterization of epitaxial III-V semiconductor thin films grown on Si(100) by ion-assisted deposition

1990 ◽  
Vol 48 (4) ◽  
pp. 686-687
Author(s):  
L. Hultman ◽  
C.-H. Choi ◽  
R. Kaspi ◽  
R. Ai ◽  
S.A. Barnett
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ion Irradiation ◽  
High Energy ◽  
Nucleation Mechanism ◽  
Layer By Layer ◽  
Extended Defect ◽  
Island Formation ◽  
Si Substrates ◽  
Transmission Electron

III-V semiconductor films nucleate by the Stranski-Krastanov (SK) mechanism on Si substrates. Many of the extended defects present in the films are believed to result from the island formation and coalescence stage of SK growth. We have recently shown that low (-30 eV) energy, high flux (4 ions per deposited atom), Ar ion irradiation during nucleation of III-V semiconductors on Si substrates prolongs the 1ayer-by-layer stage of SK nucleation, leading to a decrease in extended defect densities. Furthermore, the epitaxial temperature was reduced by >100°C due to ion irradiation. The effect of ion bombardment on the nucleation mechanism was explained as being due to ion-induced dissociation of three-dimensional islands and ion-enhanced surface diffusion.For the case of InAs grown at 380°C on Si(100) (11% lattice mismatch), where island formation is expected after ≤ 1 monolayer (ML) during molecular beam epitaxy (MBE), in-situ reflection high-energy electron diffraction (RHEED) showed that 28 eV Ar ion irradiation prolonged the layer-by-layer stage of SK nucleation up to 10 ML. Otherion energies maintained layer-by-layer growth to lesser thicknesses. The ion-induced change in nucleation mechanism resulted in smoother surfaces and improved the crystalline perfection of thicker films as shown by transmission electron microscopy and X-ray rocking curve studies.

Key Role of the Oxidized Citrate-Free Radical in the Nucleation Mechanism of the Metal Nanoparticle Turkevich Synthesis

2019 ◽  
Vol 123 (36) ◽  
pp. 22624-22633 ◽  
Author(s):  
Sarah Al Gharib ◽  
Jean-Louis Marignier ◽  
Abdel Karim El Omar ◽  
Adnan Naja ◽  
Sophie Le Caer ◽  
...  
Keyword(s):  
Free Radical ◽  
Nucleation Mechanism ◽  
Metal Nanoparticle

scholarly journals Crack Nucleation Mechanism of Austempered Ductile Iron during Tensile Deformation

2006 ◽  
Vol 47 (1) ◽  
pp. 82-89 ◽  
Author(s):  
Zenjiro Yajima ◽  
Yoichi Kishi ◽  
Ken’ichi Shimizu ◽  
Hideharu Mochizuki ◽  
Toshiki Yoshida
Keyword(s):  
Ductile Iron ◽  
Tensile Deformation ◽  
Crack Nucleation ◽  
Nucleation Mechanism ◽  
Austempered Ductile Iron

Sodium salt scaling in black liquor evaporators and the effects of the addition of tall oil brine

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Erik Karlsson ◽  
Anders Åkesjö
Keyword(s):  
Sodium Carbonate ◽  
Sodium Salt ◽  
Black Liquor ◽  
Sodium Sulphate ◽  
Salt Solutions ◽  
Tall Oil ◽  
Sulphate Content ◽  
Inhibition Effect ◽  
Salt Scaling ◽  
Primary Nucleation

AbstractSodium salt scaling, i. e. the formation of doubles salts comprised of sodium, carbonate and sulphate on the heat transfer surfaces, is a common problem that occurs during black liquor evaporation. In this study, experimental results are presented that provide new insights into the formation and composition of such scales and how they are influenced by the addition of tall oil brine. It was found that increased content of sodium carbonate and sodium sulphate in the black liquor increased scaling, while the ratio between carbonate and sulphate had a lesser influence than reported in other studies. Black liquor created loose clay-like scales comprised of aggregated crystals and black liquor, whereas salt solutions created hard mineral-like scales. The scales formed by both the black liquor and the salt solution showed a tendency to fall off during formation after primary nucleation. It was also found that both tall oil soap and alkalized tall oil brine could inhibit the formation of scales. The inhibition effect is stronger if adding the soap or brine just before scaling starts, but also depends on the amount added, the sodium carbonate and sodium sulphate content in the liquor as well as other factors.

scholarly journals Understanding the Salt-Dependent Outcome of Glycine Polymorphic Nucleation

Pharmaceutics ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 262
Author(s):  
Guangjun Han ◽  
Pui Shan Chow ◽  
Reginald B. H. Tan
Keyword(s):  
Rare Case ◽  
Depth Data ◽  
Data Analyses ◽  
Primary Nucleation ◽  
Bulk Solutions

The salt-dependent polymorphs of glycine crystals formed from bulk solutions have been a longstanding riddle. In this study, in order to shed fresh light, we studied the effects of seven common salts on primary nucleation of the metastable α-glycine and the stable γ-glycine. Our nucleation experiments and in-depth data analyses enabled us to reveal that (NH4)2SO4, NaCl and KNO3, in general, promote γ-glycine primary nucleation very significantly while simultaneously inhibiting α-glycine primary nucleation, thereby explaining why these three salts induce γ-glycine readily. In comparison, Ca(NO3)2 and MgSO4 also promote γ-glycine and inhibit α-glycine primary nucleation but not sufficiently to induce γ-glycine. More interestingly, Na2SO4 and K2SO4 promote not only γ-glycine but also α-glycine primary nucleation, which is unexpected and presents a rare case where a single additive promotes the nucleation of both polymorphs. As a result, the promoting effects of Na2SO4 and K2SO4 on γ-glycine do not enable γ-glycine nucleation to be more competitive than α-glycine nucleation, with γ-glycine failing to appear. These observations help us to better understand salt-governed glycine polymorphic selectivity.

scholarly journals Curcumin Inhibits the Primary Nucleation of Amyloid-Beta Peptide: A Molecular Dynamics Study

Biomolecules ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1323
Author(s):  
Irini Doytchinova ◽  
Mariyana Atanasova ◽  
Evdokiya Salamanova ◽  
Stefan Ivanov ◽  
Ivan Dimitrov
Keyword(s):  
Molecular Dynamics ◽  
Hydrogen Bonds ◽  
Amyloid Beta ◽  
Amyloid Plaques ◽  
Amyloid Beta Peptide ◽  
Aβ Peptides ◽  
Amyloid Peptides ◽  
Primary Nucleation ◽  
Beta Peptide ◽  
Good Agreement

The amyloid plaques are a key hallmark of neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s disease. Amyloidogenesis is a complex long-lasting multiphase process starting with the formation of nuclei of amyloid peptides: a process assigned as a primary nucleation. Curcumin (CU) is a well-known inhibitor of the aggregation of amyloid-beta (Aβ) peptides. Even more, CU is able to disintegrate preformed Aβ firbils and amyloid plaques. Here, we simulate by molecular dynamics the primary nucleation process of 12 Aβ peptides and investigate the effects of CU on the process. We found that CU molecules intercalate among the Aβ chains and bind tightly to them by hydrogen bonds, hydrophobic, π–π, and cation–π interactions. In the presence of CU, the Aβ peptides form a primary nucleus of a bigger size. The peptide chains in the nucleus become less flexible and more disordered, and the number of non-native contacts and hydrogen bonds between them decreases. For comparison, the effects of the weaker Aβ inhibitor ferulic acid (FA) on the primary nucleation are also examined. Our study is in good agreement with the observation that taken regularly, CU is able to prevent or at least delay the onset of neurodegenerative disorders.

Sign in / Sign up

Export Citation Format

Share Document