Morphological Transition Research Articles

A Versatile Approach to Stabilize Liquid-Liquid Interfaces using Surfactant Self-Assembly.

Stabilizing liquid-liquid interfaces, whether between miscible or immiscible liquids, is crucial for a wide range of applications, including energy storage, microreactors, and biomimetic structures. In this study, a versatile approach for stabilizing the water-oil interface is presented using the morphological transitions that occur during the self-assembly of anionic, cationic, and nonionic surfactants mixed with fatty acid oils. The morphological transitions underlying this approach are characterized and extensively studied through small-angle X-ray scattering (SAXS), rheometry, and microscopy techniques. Dissipative particle dynamics (DPD) as a simulation tool is adopted to investigate these morphological transitions both in the equilibrium ternary system as well as in the dynamic condition of the water-oil interface. Such a versatile strategy holds promise for enhancing applications such as liquid-in-liquid 3D printing. Moreover, it has the potential to revolutionize a wide range of fields where stabilizing liquid-liquid interfaces not only offers unprecedented opportunities for fine-tuning nanostructural morphologies but also imparts interesting practical features to the resulting liquid shapes. These features include perfusion capabilities, self-healing, and porosity, which could have significant implications for variousindustries.

A putative cAMP-binding protein in Trypanosoma brucei cooperates with FLAM3 to promote flagellar connection and cell morphogenesis

Trypanosoma brucei is a flagellated parasitic protozoan, and within the insect vector the parasite transitions from the trypomastigote form to the epimastigote form by re-positioning its mitochondrial genome and re-locating the flagellum. The mechanisms underlying such morphology changes are still poorly understood, but several flagellum-localized proteins are involved in this process by modulating the flagellum attachment zone (FAZ) that adheres the flagellum to the cell membrane. We report here a putative cAMP-binding protein named cAMP-BP1, which promotes flagellar connection and morphology transition. cAMP-BP1 contains two cyclic nucleotide-binding domains and five calcium-binding C2 domains and localizes to the flagella connector and the new FAZ tip. Depletion of cAMP-BP1 in the trypomastigote form of T. brucei causes major morphology changes, generating epimastigote-like cells with re-positioned kinetoplast and re-located flagellum. At the flagella connector and the new FAZ tip, cAMP-BP1 associates with FLAM3, a regulator of morphology transition, depends on the latter for localization, and is required for FLAM3 localization to the flagella connector. Knockdown of cAMP-BP1 inhibits FAZ elongation and disrupts flagellar connection by impairing flagella connector structural integrity. These results identify a flagella connector- and new FAZ tip-localized protein as a regulator of morphology transition and flagellar connection in trypanosomes and uncover its functional interplay with FLAM3 to promote FAZ elongation for maintaining trypomastigote morphology.

Inhibition of Candida albicans virulence by moscatin from Dendrobium nobile lindl.

Candida albicans infection poses a significant global health threat. It is imperative to exploit new antifungal agents against C. albicans infections without leading to drug resistance, so that these potential agents can complement or combine with current medications to effectively treat diseases caused by C. albicans. We screened moscatin, and assessed the inhibitory effectiveness against C. albicans SC5314 on hyphae production and biofilm formation. It was revealed that moscatin exhibited significant effects on morphological transition and biofilm formation in C. albicans SC5314. It also lowered the pathogenicity of C. albicans SC5314 in a concentration-dependent way in both A549 cells and mice fungal infection models, but had no cytotoxicity to A549 cells. In addition, moscatin attenuated the virulence of clinical fluconazole-resistant C. albicans and exhibited synergistic activity with fluconazole. It could also restore the composition and richness of the intestinal microbiota in mice infected by C. albicans. These findings indicate that these moscatin has great potential to be developed as a new therapeutic drug against C. albicans infection.

Enhanced CO2 Hydrogenation Performance of CoCrNiFeMn High Entropy Alloys

CO2 hydrogenation is a promising process for removing anthropogenic CO2 emissions and yielding C1 chemicals that can be utilized as fuels and valuable precursors for chemical synthesis. Commercial high-entropy alloys (HEAs) have widespread application in various fields owing to their exceptional thermal stability and tunable microstructure. However, their potential application as catalysts is often limited by the low exposure of active sites. In this study, the commercial CoCrNiFeMn powder was applied for atmospheric pressure CO2 hydrogenation and enhanced its catalytic performance by a combined treatment of ball milling and high-temperature H2 reduction. The high-energy ball milling results in a morphological transition in CoCrNiFeMn HEAs from spherical to irregular. This transformation leads to a significant decrease in particle size and more surface reactive sites. The high-temperature H2 reduction promoted the atomic rearrangement on the CoCrNiFeMn surface, thereby improving its alloy structural homogeneity. These modifications greatly improve the performance of CoCrNiFeMn for CO2 hydrogenation. This work introduces a facile modification approach to facilitate the catalytic efficiency of commercial HEAs in CO2 hydrogenation with high selectivity.

Co‐encapsulation of ω‐3 LC‐PUFAs and carotenoids for enhanced synergistic antioxidant effects

AbstractThis work aimed to study the co‐encapsulation of ω‐3 Long‐Chain Polyunsaturated Fatty Acids (LC‐PUFAs) with β‐carotene, lutein and zeaxanthin and the cellular uptake of carotenoids. Monodisperse microcapsules with good properties, including particle surface morphology, water activity, microencapsulation efficiency, and glass transition temperature, were successfully prepared using a microfluidic‐jet spray drier with OSA‐modified starch as a wall matrix. The presence of carotenoids enhanced the oxidative stability of ω‐3 LC‐PUFAs. Caco‐2 cell uptakes of the carotenoids from the spray‐dried microcapsules were studied and compared to those encapsulated in the methylcellulose (MC) or xanthan gum (XG) delivery systems. The microcapsules encapsulated by OSA‐modified starch showed higher cellular uptakes of carotenoids (i.e., β‐carotene, 0.31 μg/mg protein; lutein, 0.52 μg/mg protein; zeaxanthin, 0.54 μg/mg protein) than those in the MC or XG delivery systems. The Caco‐2 cell uptake depended on carotenoid type, where hydrocarbon carotenoids (i.e., β‐carotene) had lower uptake than oxygenated carotenoids (i.e., lutein or zeaxanthin).

Study of arc and magnetic field parameters under delayed breaking condition of DB-DC VCB

Taking the mechanical double-break DC vacuum circuit breaker (DB DC VCB) as the research object, the magnetic field and temperature field distribution between the breaks and the plasma characteristics under the working condition of gap difference caused by actuator dispersion are investigated to explore the difference in arc characteristics between the two breaks. Based on the system of Maxwell and magnetohydrodynamic (MHD) equations, a non-simultaneous breaking model of the DB DC VCB is established, and parameters such as magnetic flux density, plasma velocity, inter-contact pressure, and ion and electron temperatures are calculated. The simulation results show that the cathode surface field emission effect is stronger in the small gap break (delayed breaking break). Besides, in the small gap break, the arc temperature is higher, the rate of decrease of temperature is lower, the electron velocity is higher, the magnetic flux density is lower, the regulatory ability of the magnetic field is weaker, and the plasma diffusion speed is slower. In the arc ignition stage, the arc aggregation state duration of the small gap break is longer than that of the normal break, which means the arc in the small gap break gets diffused and arc energy dissipation becomes harder. Therefore, the arc energy density of the delayed breaking break is greater, the arc morphology transition time is longer, the residual particle concentration after arc extinguishing is higher, and the probability of re-strike breakdown increases with the increase in gap difference. Improving the synchronization of the actuator could improve the breaking ability of the DB DC VCB. Index terms—plasma arc, double-break direct current vacuum circuit breaker (DB-DC VCB), transverse magnetic field (TMF), magnetohydrodynamic (MHD) model.

Directionally solidified NiCoCrFeAlW eutectic high-entropy alloy: Microstructure and mechanical properties

The NiCoCrFeAlW eutectic high-entropy alloy exhibits a balanced combination of ductility and strength. This study examines the microstructure evolution and mechanical properties of the Ni30Co30Cr10Fe10Al18W2 alloy at varying growth velocities (10, 20, 50, 100, and 200 μm/s), which in its as-cast state, features a microstructure that includes both coarse dendrites and lamellar eutectic. The structure of the coarse dendrites is characterized by an ordered body-centered cubic (B2) phase, while the lamellar eutectic, features a combination of face-centered cubic (FCC) and ordered B2 phases. The microstructure, characterized by lamellar and dendritic structures that are parallel to the growth direction after directional solidification, undergoes a morphological transition at the solid-liquid interface from a planar to a dendritic form as growth velocity increases. The tensile fracture strength initially increases with the growth velocity, reaching a peak of 1286 MPa at a velocity of 50 μm/s, and then subsequently decreases as the growth velocity continues to increase. Directional solidification results in an increase in sample elongation with increasing growth velocity, achieving an elongation of 22.5% at 200 μm/s. An examination of the deformation mechanism reveals that the lamellar structure, composed of the more ductile FCC phase and the harder B2 phase, effectively harmonizes the plasticity and strength of the alloy. Therefore, directional solidification significantly adjusts the eutectic microstructure's orientation, thereby enhancing the mechanical properties along the direction of solidification.

A lattice Boltzmann model with sharp interface tracking for the motion and growth of dendrites in non-equilibrium solidification of alloys

A lattice Boltzmann model (LBM) with sharp interface tracking is developed to simulate the motion and growth of dendrites in non-equilibrium solidification of alloys. The model is validated through comparative analysis with the drafting-kissing-tumbling (DKT) phenomena of two and three particles and the continuous growth model (CGM), and demonstrates its computational efficiency advantage without compromising accuracy by comparison with the multi-phase field (MPF) model. Subsequently, the model is utilized to investigate the dendrite morphology transition and primary dendritic arm spacing (PDAS). It is found that the velocity dependent solute partition and the resulting changes in constitutional undercooling strongly influence the estimated morphology region and PDAS. Moreover, the segregation and microstructure evolution during the rapid solidification were studied. And the results revealed that free dendrites lead to significant changes in microstructure and segregation under the influence of non-equilibrium effects. This work illustrates the great potential of the proposed model in simulating dendrites and microstructure evolution under a wide range of solidification conditions. Its suitability for extreme conditions and non-equilibrium solidification can contribute to the understanding of microstructure formation patterns and solute segregation in rapid solidification.

Optimizing damage resistance and structural evolution in CaO-modified Li2O-Al2O3-B2O3-TiO2-P2O5 glass-ceramics

Aluminoborate glass, recognized for its remarkable crack resistance, presents significant potential as a cover material for portable electronic devices. Nevertheless, its relatively low hardness has been a limiting factor. This study synthesized a series of 11 Li2O-30 Al2O3-(55-x) B2O3-2 TiO2-2 P2O5-xCaO (wt%), with x varying from 0 to 10, employing the melt-cast method. The resultant glass-ceramics were produced via heat treatment at 590 °C for 2 h, followed by a systematic examination of their structural and mechanical properties. The investigation demonstrated that an increase in CaO content diminishes crystallization and induces a morphological transition in the crystalline phases from granular and short rod-like structures to lath-like formations, which subsequently impacts the coordination environment of Al and B atoms. With a CaO content of 2 %, the GC2 sample precipitated Li(Al7B4O17) and Li2AlB5O10 phases, achieving a compressive strength (CR) value of 15.0 N, a hardness of 7.51 GPa, and a fracture toughness of 1.50 MPa m0.5. This glass-ceramic exhibited optimal scratch resistance and visible light transmittance exceeding 85 %, underscoring its considerable promise for application as smartphone cover glass due to its impressive overall damage resistance.

Response of the distribution and molecular transition of gluten proteins and quality of Chinese steamed bread to different hydration levels

This study systematically explored how different hydration levels (45 %, 50 %, and 55 % water addition) affect the evolution of gluten network morphology, distribution, conformational and molecular transition, and moisture migration during the processing of Chinse steamed bread (CSB), and their impact on quality formation. Higher hydration levels resulted in a more uniform distribution and fibrous structure of the gluten network during mixing. However, excessive hydration (55 %) caused gluten fibers to rupture during fermentation. This increased the specific volume but decreased the chewiness and stickiness of CSB. MRI results highlighted that differences in moisture migration and internal structure among samples with different hydration levels were enlarged after steaming. AFM images revealed the increase in both protein molecular chain height and width with increasing hydration level, particularly after steaming. Moreover, high hydration levels promoted the depolymerization of glutenin macropolymers during mixing, fermentation, as well as repolymerization during cooking. These results indicated that both macroscopic qualities and molecular structure of gluten protein became more sensitive to the physical and biochemical processes during CSB processing. These dynamic transitions play a crucial role in determining dough rheological properties and CSB's overall quality. This research offers theoretical insights for precise dough product regulation and understanding underlying mechanisms.

Measurement of adhesion and traction of cells at high yield reveals an energetic ratchet operating during nephron condensation

Developmental biology-inspired strategies for tissue-building have extraordinary promise for regenerative medicine, spurring interest in the relationship between cell biophysical properties and morphological transitions. However, mapping gene or protein expression data to cell biophysical properties to physical morphogenesis remains challenging with current techniques. Here, we present multiplexed adhesion and traction of cells at high yield (MATCHY). MATCHY advances the multiplexing and throughput capabilities of existing traction force and cell-cell adhesion assays using microfabrication and a semiautomated computation scheme with machine learning-driven cell segmentation. Both biophysical assays are coupled with serial downstream immunofluorescence to extract cell type/signaling state information. MATCHY is especially suited to complex primary tissue-, organoid-, or biopsy-derived cell mixtures since it does not rely on a priori knowledge of cell surface markers, cell sorting, or use of lineage-specific reporter animals. We first validate MATCHY on canine kidney epithelial cells engineered for rearranged during transfection (RET) tyrosine kinase expression and quantify a relationship between downstream signaling and cell traction. We then use MATCHY to create a biophysical atlas of mouse embryonic kidney primary cells and identify distinct biophysical states along the nephron differentiation trajectory. Our data complement expression-level knowledge of adhesion molecule changes that accompany nephron differentiation with quantitative biophysical information. These data reveal an "energetic ratchet" that accounts for spatial trends in nephron progenitor cell condensation as they differentiate into early nephron structures, which we validate through agent-based computational simulation. MATCHY offers semiautomated cell biophysical characterization at >10,000-cell throughput, an advance benefiting fundamental studies and new synthetic tissue strategies for regenerative medicine.

Multicompartment microparticles of SBM triblock terpolymers: Morphological transitions through homopolymer blending

AbstractBlock copolymers (BCPs) have recently been explored in spherical confinement to form internally structured microparticles. While the behavior of AB diblock copolymers in confinement is comparably well studied, knowledge on confined ABC triblock terpolymers is still rather sparse. The latter are especially interesting as the third block allows the formation of a broader variety of multicompartment microparticles (MMs), but their synthesis is often realized through sequential polymerization, which can be work intensive and challenging. Here, we demonstrate that blending linear ABC triblock terpolymers with homopolymers is a versatile and straightforward method to tune the microphase behavior in MMs. We systematically blend polystyrene-block-polybutadiene-block-poly(methyl methacrylate) (SBM or PS-b-PB-b-PM) with homopolymers of hPS, hPB, or hPM, to study the feasibility of this approach to replicate specific morphologies or access new ones. We utilize Shirasu Porous Glass (SPG) membrane emulsification and evaporation-induced confinement assembly (EICA) to produce narrowly size-dispersed MMs with defined inner structure. We analyze the MMs with dynamic light scattering (DLS), as well as transmission and scanning electron microscopy (TEM, SEM). We show that the resulting blend morphologies can be identical to those of the unblended SBM at same composition and that, depending on the location in the ternary microphase diagram, one SBM morphology can be converted into multiple different morphologies. Graphical Abstract

Myotube Guidance: Shaping up the Musculoskeletal System.

Myofibers are highly specialized contractile cells of skeletal muscles, and dysregulation of myofiber morphogenesis is emerging as a contributing cause of myopathies and structural birth defects. Myotubes are the myofiber precursors and undergo a dramatic morphological transition into long bipolar myofibers that are attached to tendons on two ends. Similar to axon growth cones, myotube leading edges navigate toward target cells and form cell-cell connections. The process of myotube guidance connects myotubes with the correct tendons, orients myofiber morphology with the overall body plan, and generates a functional musculoskeletal system. Navigational signaling, addition of mass and volume, and identification of target cells are common events in myotube guidance and axon guidance, but surprisingly, the mechanisms regulating these events are not completely overlapping in myotubes and axons. This review summarizes the strategies that have evolved to direct myotube leading edges to predetermined tendon cells and highlights key differences between myotube guidance and axon guidance. The association of myotube guidance pathways with developmental disorders is also discussed.

Antifungal activities of Equol against Candida albicans in vitro and in vivo

ABSTRACT Candida albicans is an opportunistic fungal pathogen that can cause systemic infections in immunocompromised individuals. Morphological transition and biofilm formation are major virulence factors of C. albicans. Moreover, biofilm enhances resistance to antifungal agents. Therefore, it is urgent to identify new and effective compounds to target the biofilm of C. albicans. In the present study, the antifungal activities of equol against C. albicans were investigated. In vitro, the microdilution analysis and spot assay result showed that equol exhibited potent inhibitory activities against C. albicans. Further investigations confirmed that the antifungal effects of equol involved interference with the transition from yeast to hypha and biofilm formation of C. albicans. In addition, transcriptome sequencing and reverse transcription-quantitative PCR (qRT-PCR) analysis showed that equol significantly downregulated the expression of several genes in the Ras1-cAMP-PKA pathway related to hyphae and biofilm formation and significantly upregulated the expression of the negative transcriptional repressors RFG1 and TUP1. Moreover, equol effectively reduced the production of cAMP, a key messenger in the Ras1-cAMP-PKA pathway, while supplementation with cAMP partly rescued the equol-induced defects in hyphal development. Furthermore, in a mouse model of systemic candidiasis (SC), equol treatment significantly decreased the fungal burden (liver, kidneys, and lung) in mice and local tissue damage, while enhancing the production of interleukin-10 (IL-10). Together, these findings confirm that equol is a potentially effective agent for treatment of SC.

The yeast Dothiora sorbi IOJ-3 naturally produced various filamentous sectors with distinct abilities by undergoing DNA demethylation

Some fungi have demonstrated the ability to adapt rapidly to changing environments by exhibiting morphological plasticity, a trait influenced by species and environmental factors. Here, an anamorphic yeast strain IOJ-3 exhibited unique sectorization characteristics, naturally producing diverse filamentous sectors when cultivated on potato dextrose agar (PDA) medium or natural culture medium for durations exceeding 13 days. The strain IOJ-3 and its filamentous sectors were identified as Dothiora sorbi. The morphology of the sectors was consistent and heritable. The life cycle of strain IOJ-3 was investigated through microscopic observation, emphasizing the development of conidiogenous cells as a crucial stage, from which filamentous sectors originate. Some physiological characteristics of IOJ-3 and filamentous sectors are compared, and strain IOJ-3 has a higher antibiotic tolerance than two filamentous sectors, IOJ-3a expands faster on the culture medium, and IOJ-3b can penetrate cellophane. A transcriptomic analysis was conducted to investigate the differentially expressed genes between the yeast form IOJ-3 and its two filamentous sectors, revealing a total of 594 genes that exhibited consistent differential expression relative to IOJ-3, including 44 silencing genes in IOJ-3 that were activated. Gene Ontology analysis indicated that these differentially expressed genes were primarily associated with the cellular component category. Furthermore, adding 5-Azacytidine accelerated filamentous sectorization and increased the proportion of filamentous cells of strain IOJ-3 in PD liquid media, suggesting that the filamentous sectorization observed in strain IOJ-3 is linked to processes of DNA demethylation. In conclusion, this study sheds light on the biological characteristics of D. sorbi regarding morphological transitions and provides substantial direction for exploring genes related to fungal filamentous development.

ASLdC3: A Derivative of Acidic Sophorolipid Disrupts Mitochondrial Function, Induces ROS Generation, and Inhibits Biofilm Formation in Candida albicans.

Fungal infections account for more than 140 million cases of severe and life-threatening conditions each year, causing approximately 1.7 million deaths annually. Candida albicans and related species are the most common human fungal pathogens, causing both superficial (mucosal and cutaneous) and life-threatening invasive infections (candidemia) with a 40-75% mortality rate. Among many virulence factors of Candida albicans, morphological transition from yeast to hyphae, secretion of hydrolytic enzymes, and formation of biofilms are considered to be crucial for pathogenicity. However, the arsenals for the treatment against these pathogens are restricted to only a few classes of approved drugs, the efficacy of which is being compromised by host toxicity, fungistatic activity, and the emergence of drug resistance. In this study, we have described the development of a molecule, exhibiting excellent antifungal activity (MIC 8 μg/mL), by tailoring acidic sophorolipids with aryl alcohols via enzyme catalysis. This novel derivative, ASLdC3, is a surface-active compound that lowers the surface tension of the air-water interface up to 2-fold before reaching the critical micelle concentration of 25 μg/mL. ASLdC3 exhibits excellent antibiofilm properties against Candida albicans and other nonalbicans Candida species. The molecule primarily exhibits its antifungal activity by perturbing mitochondrial function through the alteration of the mitochondrial membrane potential (MMP) and generation of reactive oxygen species (ROS). The ROS damages fungal cell membrane function and cell wall integrity, eventually leading to cell death. ASLdC3 was found to be nontoxic in in vitro assay and nonhemolytic. Besides, it does not cause toxicity in the C. elegans model. Our study provides a valuable foundation for the potential of acidic sophorolipid as a nontoxic, biodegradable precursor for the design and synthesis of novel molecules for use as antimicrobial drugs as well as for other clinical applications.

Microstructure and Tribological Properties of WC/Ni-MoS2 Titanium-Based Composite Coating on TC4

To improve the mechanical properties of a TC4 surface, TC4 + Ni-MoS2 + xWC (x = 5%, 10% and 15% wt.%) composite coatings were prepared by the coaxial feeding laser cladding technique, and the effect of the WC content on the microstructure and tribological properties of the coatings were investigated using multiple characterization methods. The results indicated that increasing the WC content negatively impacted the forming quality of the coating, but did not change the coating phase which predominantly comprised Ti2Ni, Ti2S, TiC, matrix β-Ti and residual WC. With the addition of WC, TiC exhibited an increase in both quantity and particle size, accompanied by a transition in growth morphology from spherical to petal-like. MoS2 completely dissolved in all coatings and the S element provided by it effectively synthesized a strip-like phase Ti2S which presented a morphology similar to the lubricating phase TiS in the Ti-based melt pool system. The microhardness and wear-resistance of all the coatings were higher than that of TC4 and gradually improved with the addition of WC, which indicated that raising the WC content was conducive to enhancing the mechanical properties of the coatings. The friction coefficient of TC4 was lower than that of the three WC content coatings, indicating that Ti2S was not the lubricating phase. The wear mechanism of all coatings was abrasive wear.

Mechano-osmotic signals control chromatin state and fate transitions in pluripotent stem cells.

Acquisition of specific cell shapes and morphologies is a central component of cell fate transitions. Although signaling circuits and gene regulatory networks that regulate pluripotent stem cell differentiation have been intensely studied, how these networks are integrated in space and time with morphological transitions and mechanical deformations to control state transitions remains a fundamental open question. Here, we focus on two distinct models of pluripotency, primed pluripotent stem cells and pre-implantation inner cell mass cells of human embryos to discover that cell fate transitions associate with rapid changes in nuclear shape and volume which collectively alter the nuclear mechanophenotype. Mechanistic studies in human induced pluripotent stem cells further reveal that these phenotypical changes and the associated active fluctuations of the nuclear envelope arise from growth factor signaling-controlled changes in chromatin mechanics and cytoskeletal confinement. These collective mechano-osmotic changes trigger global transcriptional repression and a condensation-prone environment that primes chromatin for a cell fate transition by attenuating repression of differentiation genes. However, while this mechano-osmotic chromatin priming has the potential to accelerate fate transitions and differentiation, sustained biochemical signals are required for robust induction of specific lineages. Our findings uncover a critical mechanochemical feedback mechanism that integrates nuclear mechanics, shape and volume with biochemical signaling and chromatin state to control cell fate transition dynamics.

The Effect of Long-Term Aging on the Microstructure and Properties of a Novel Nickel-Based Powder Superalloy FGH4113A.

This study investigates the microstructural evolution and its effect on the fatigue performance of a novel nickel-based powder superalloy FGH4113A (WZ-A3) after long-term aging at 760 °C and 815 °C. The results show that long-term aging both at 760 °C and 815 °C has no significant effect on the grain size and morphology of the alloy. After aging at 760 °C for up to 2020 h, the size of the γ' phase remains unchanged, and its morphology transitions from nearly square to nearly spherical. During long-term aging at 815 °C for 440 h, γ' phase coarsening and spheroidizing occur simultaneously. With prolonged aging time, the size and spheroidization degree of the γ' phase further increase. During long-term aging up to 440 h at 760 °C, the dispersed granular MC and M6C carbides dissolve and re-precipitate. By 2020 h of aging, flocculent carbides precipitate and non-continuous M6C and M23C6 accumulate at grain boundaries. After long-term aging at 815 °C for 440 h, flocculent carbides begin to precipitate within the grains. By 2020 h of aging, a large amount of flocculent carbides precipitate with significant coarsening and enrichment of the grain boundary carbides. Due to the insignificant coarsening of the γ' phase as well as the enrichment and precipitation of the grain boundary carbides, the fatigue performance of the alloy decreases slightly after long-term aging.

Pickering emulsification of pyrrolidone-based block copolymer aggregates: Effects of copolymer composition and oil

A series of block copolymers poly (N-2-(methacryloyloxy) ethyl pyrrolidone)-b-poly (benzylmethacrylate) (PNMP39-b-PBzMAn) were developed. These amphiphilic copolymers formed diversified aggregates in water, depending on the degree of polymerization n of the PBzMA segment. There presented the n-induced morphological transition from spherical micelles to vesicles via wormlike micelles. Moreover, PNMP39-b-PBzMAn aggregates were excellent dual function emulsifiers, showing similarity with both particles and surfactants simultaneously. The emulsification of PNMP39-b-PBzMAn aggregates was affected significantly by the degree of polymerization n of the PBzMA segment and oil. However, the effect of oil was more remarkable in comparison with that of n, in which the compatibility between oil and the hydrophobic PBzMA segment was critical. In general, O/W and W/O emulsions were formed for oils with poor and good compatibility to the PBzMA segment such as nonpolar alkanes and toluene, respectively. In these cases, PNMP39-b-PBzMAn aggregates were remained in water in the alkane/water systems, whereas they were transferred into the toluene phase according to the similarity-intermiscibility principle. For isopropyl myristate, a polar oil with the intermediate compatibility to the PBzMA segment, PNMP39-b-PBzMAn in water were transferred into the oil phase partially. Accordingly, emulsifiers in water and oil benefit the formation of O/W and W/O emulsions, respectively, as observed in the alkane/water and toluene/water systems. As a result, O/W and W/O emulsions were generated by PNMP39-b-PBzMAn with relatively small and large n, respectively. For PNMP39-b-PBzMAn with the intermediate n, W/O/W multiple emulsions were formed attributing to the synergistic emulsification of PNMP39-b-PBzMAn in water and oil.