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• A quantitative method was proposed to assess the shear stability of AGS. • Parameter a had a strong positive linear correlation with the wet density of AGS. • LGS represented the equilibrium size for AGS after sheared for a period of time. • LGS was significantly and exponentially related to the parameter a. • The results were validated with the AGS samples from a pilot-scale AGS-MBR. This work established a quantitative method to access the shear stability of aerobic granular sludge (AGS) and validated its feasibility by using the mature AGS from a pilot-scale (50 tons/day) membrane bioreactor (MBR) for treating real municipal wastewater. The results showed that the changing rate (Δ S) of the peak area (S) of granule size distribution (GSD) exhibited an exponential relationship (R 2≥0.76) with the shear time (y = a − b · c x), which was a suitable indicative index to reflect the shear stability of different AGS samples. The limiting granule size (LGS) was defined and proposed to characterize the equilibrium size for AGS after being sheared for a period of time, whose value in terms of Dv50 showed high correlation (R 2=0.92) with the parameter a. The free Ca2+ (28.44–34.21 mg/L) in the influent specifically interacted with polysaccharides (PS) in the granule's extracellular polymeric substance (EPS) as a nucleation site, thereby inducing the formation of Ca precipitation to enhance its Young's modulus, while Ca2+ primarily interacted with PS in soluble metabolic product (SMP) during the initial granulation process. Furthermore, the Young's modulus significantly affected the parameter a related to shear stability (R 2=0.99). Since the parameter a was more closely related (R 2=1.00) to Δ S than that of the parameter b or c , the excellent correlation (R 2=0.99) between the parameter a and the wet density further verified the feasibility of this method. [Display omitted] [ABSTRACT FROM AUTHOR]

Low concentration polymer additives can significantly alter crystal growth kinetics of molecular liquids and glasses. However, the effect of polymer concentration on nucleation kinetics remains poorly understood. Based on an experimentally determined first nucleation time (time to form the first critical nucleus, t 0), we show that the polymer overlap concentration, c *, where polymer coils in the molecular liquid start to overlap with each other, is a critical polymer concentration for efficient inhibition of crystallization of a molecular liquid. The value of t 0 is approximately equal to that of the neat molecular liquid when the polymer concentration, c , is below c *, but increases significantly when c > c *. This finding is relevant for effective polymer screening and performance prediction of engineered multicomponent amorphous materials, particularly pharmaceutical amorphous solid dispersions. [Display omitted] [ABSTRACT FROM AUTHOR]

A thorough understanding of effects of polymers on crystallization of amorphous drugs is essential for rational design of robust amorphous solid dispersion (ASD), since crystallization of the amorphous drug negates their solubility advantage. In this work, we measured the first nucleation time (t 0 , time to form the first critical nucleus in fresh liquid/glass) in posaconazole (POS)/polyvinylpyrrolidone vinyl acetate (PVPVA) and POS/polyvinylpyrrolidone (PVP K25) ASDs and showed that the polymer overlap concentration (c *, concentration above which adjacent polymer chains begin to contact) is critical in controlling crystallization of ASDs. When polymer concentration c < c *, t 0 of POS ASDs is approximately equal to that of the neat amorphous POS, but it increases significantly when c > c *. This observation supports the view that the effective inhibitory effect of crystallization in ASDs above c * is primarily correlated with delay in the first nucleation event. Our finding is useful in efficient polymer selection and performance prediction of high drug loaded ASD formulations. [Display omitted] [ABSTRACT FROM AUTHOR]

Mg-Ti oxide/MnS complex inclusions effectively serve as nucleation sites for intragranular ferrite. This study employs first-principles calculation methods to investigate the inducing properties of complex inclusions, including the growth of MnS on Ti oxide, the absorption of Mn atoms by Ti oxide, and the diffusion behavior of Mn atoms within Ti oxide, both untreated and Mg-treated. Ti 2 O 3 indicates the untreated group, while MgTiO 3 indicates the Mg-treated group. Computational analysis indicated that MnS is more likely to adsorb and grow on MgTiO 3 than on Ti 2 O 3. MnS vertically grows on the O-Mg-Mg surface of MgTiO 3. By calculating the dissociation energy, it can be determined that the Mn in the oxide of the MnS/oxide complex inclusions originates from the steel matrix rather than from MnS. By analyzing the diffusion behavior of vacancies and Mn atoms through energy barrier calculations, it is evident that the addition of Mg alters the diffusion pathways of Mn atoms in Ti oxide and confirms that the bonding between Mn and O is the limiting step for Mn atom diffusion within the oxides. The diffusion path of Mn atoms in MgTiO 3 is Path I → Path II → Path I. Path I: Mn atoms diffuse within the cationic layer. Path II: Mn atoms diffuse by traversing across two layers of O atoms. [ABSTRACT FROM AUTHOR]

Self-supporting zeolitic foams were synthesized by a geopolymer gel conversion process, employing silicon powder and hydrogen peroxide as foaming additives. The influence of silicon and hydrogen peroxide combination on the physical properties, mechanical characteristics, and pore distribution was studied. Correlations between these properties were drawn. This approach allows to manufacture porous monoliths tuned in terms of zeolite type and amount and characterized by bulk density ranging between 573 and 762 kg/m3 and thermal conductivity 0.33–0.53 W/mK. Pore structure, size, and distribution were dominated by the type of foaming agent: the foamed samples showed the presence of two classes of pores, the first of the order of magnitude of 1 μm, the second of the order of magnitude of 100 μm. The use of hydrogen peroxide enhanced the porosity in the meso-macropore range (0.1–5 μm). The hydrothermal treatment performed on the foamed geopolymer allowed to achieve the crystallization of zeolites within the solid geopolymer. Mainly FAU and LTA were the zeolitic phases present in the foams, whereas the use of silicon as foaming agent locally increased the Si/Al ratio on the geopolymer surface, promoting the nucleation of FAU. [ABSTRACT FROM AUTHOR]

Microtubule nucleation is templated by the γ-tubulin ring complex (γ-TuRC), but its structure deviates from the geometry of α-/β-tubulin in the microtubule, explaining the complex's poor nucleating activity. Several proteins may activate the γ-TuRC, but the mechanisms underlying activation are not known. Here, we determined the structure of the porcine γ-TuRC purified using CDK5RAP2's centrosomin motif 1 (CM1). We identified an unexpected conformation of the γ-TuRC bound to multiple protein modules containing MZT2, GCP2, and CDK5RAP2, resulting in a long-range constriction of the γ-tubulin ring that brings it in closer agreement with the 13-protofilament microtubule. Additional CDK5RAP2 promoted γ-TuRC decoration and stimulated the microtubule-nucleating activities of the porcine γ-TuRC and a reconstituted, CM1-free human complex in single-molecule assays. Our results provide a structural mechanism for the control of microtubule nucleation by CM1 proteins and identify conformational transitions in the γ-TuRC that prime it for microtubule nucleation. [Display omitted] • Purification and cryo-EM reconstruction of the γ-TuRC from mammalian brain tissue • Identification of CDK5RAP2-, MZT2-, and GCP2-containing (CMG) modules bound to the γ-TuRC • The CMG-decorated γ-TuRC is in a partially closed conformation • CDK5RAP2 promotes CMG decoration and microtubule nucleation in single-filament assays Xu et al. show that CDK5RAP2's conserved CM1 motif activates the γ-tubulin ring complex by forming MZT2-dependent structural modules that promote an open-to-partially-closed conformational change in the complex. [ABSTRACT FROM AUTHOR]

To organize microtubules, cells tightly control the activity of the microtubule nucleator γ-tubulin ring complex (γTuRC). The open ring-shaped γTuRC was proposed to nucleate microtubules by a template mechanism. However, its splayed structure does not match microtubule symmetry, leaving it unclear how γTuRC becomes an efficient nucleator. Here, we identify the mechanism of γTuRC activation by CDK5RAP2 centrosomin motif 1 (CM1). Using cryoelectron microscopy (cryo-EM), we find that activation involves binding of multiple CM1 dimers to five distinct sites around the outside of the γTuRC cone, which crucially depends on regulatory modules formed by MZT2 and the N-terminal extensions of GCP2 subunits. CM1 binding promotes lateral interactions between GCP subunits to facilitate microtubule-like conformations and release of luminal actin that is integral to non-activated γTuRC. We propose a model where generation of γTuRC with an expanded conformational range, rather than perfect symmetry, is sufficient to boost nucleation activity. [Display omitted] • Dimerized CM1 motif efficiently activates the asymmetric microtubule nucleator γTuRC • Cryo-EM identifies five CM1 dimers bound to the outside of activated γTuRC • Mutation of the CM1-binding site prevents γTuRC activation • γTuRC decorated by CM1 can adopt conformations that resemble microtubule symmetry The microtubule nucleator γTuRC was proposed to require a symmetry-promoting conformational change for efficient nucleation. Using biochemical reconstitution and cryo-EM, Serna et al. show that direct binding of the nucleation activator CM1 to γTuRC does not induce a complete conformational switch but allows γTuRC to adopt more symmetric, microtubule-like conformations. [ABSTRACT FROM AUTHOR]

This work prepared [GeSb 9 (x nm)/Ga 3 Sb 7 (16-x nm)] 5 multi-layer phase change thin films and studied their related properties. Compared to traditional GST and GeSb 9 , [GeSb 9 (6 nm)/Ga 3 Sb 7 (10 nm)] 5 multi-layer phase change thin films have a higher crystallization temperature (∼205 °C) and an extremely low resistance drift coefficient (0.0004). The crystalline behavior and bonding of thin films are analyzed to elucidate their intrinsic mechanisms, thermal stability, and interfacial effects. According to crystal mechanism analysis, the Avrami index (n) is 0.904, indicating that the [GeSb 9 (6 nm)/Ga 3 Sb 7 (10 nm)] 5 multi-layer phase change thin films grow in one dimension. The presence of interfaces alters the crystallization behavior of crystals, leading to a growth mode that transitions from diffusion-controlled to interface-controlled and back to diffusion-controlled. This transformation significantly reduces the nucleation index (m ≤ 0.16), minimizing the inherent randomness of the film itself and achieving extremely low resistance drift. Research has demonstrated that [GeSb 9 (6 nm)/Ga 3 Sb 7 (10 nm)] 5 multi-layer phase change materials have promising applications in embedded memory. [ABSTRACT FROM AUTHOR]

This paper presents a study on the microstructure and magnetic properties of LaCoO 3 (LCO) thin films, and also the micropatterning of LCO thin films using a novel photo-sensitive sol-gel lithography method. It is found that higher heat-treatment temperature can promote the healing of cracks and filling of pores, resulting in refining the grains, and improving the density of LCO film. The film treated at 850 °C has a larger nucleation energy, which makes the distribution of nucleation sites more uniform, promoting the healing of cracks and filling of pores, refining the grains, and improving the density of LCO film. LCO precursor sol, metal chelates with UV photosensitivity were synthesized by adding BzAcH photosensitizer. LCO micro-arrays with diameters of 50 μm, as well as other fine patterns with a minimum line width of about 2 μm were successfully prepared by a UV mask lithography technique. In contrast, our novel lithography method eliminates the need for photoresist, as the fine pattern is formed during the preparation of the LCO gel film, which is the advantages of our lithography method over traditional techniques. [ABSTRACT FROM AUTHOR]

Photosensitive glass-ceramics exhibit significant potential to replace silicon materials in the microfabrication of micro-electro-mechanical-system (MEMS) devices. However, they are constrained by the limitations of a conventional 320-nm photolithography process. Therefore, developing an ideal industrial i-line (365 nm) photolithography for Li 2 O–Al 2 O 3 –SiO 2 photosensitive glass-ceramics is urgently needed. This study initially explores the impact of a facile i-line photolithography on the structure and physicochemical properties of photosensitive glass ceramics. We experimentally showcase a direct, scalable, and straightforward i-line photolithography technique for Li 2 O–Al 2 O 3 –SiO 2 photosensitive glass ceramics. Our research concentrates on how the exposure time affects the properties of Li 2 O–Al 2 O 3 –SiO 2 photosensitive glass ceramics, particularly regarding nucleation and crystallization. This is achieved by adjusting the exposure time parameter and utilizing XRD, etching experiments, SEM, TEM, and other tests under a i-line light source. By optimizing the exposure process parameters, we also modify the annealing process parameters affecting the crystallization of lithium metasilicate in the exposed areas. Under a treatment process involving an exposure time of 20 min, a nucleation temperature of 500 °C, a crystallization temperature of 630 °C, and a nucleation/crystallization duration of 2 h, the sample achieves the highest crystal quantity and the optimal thickness-etching rate ratio. [ABSTRACT FROM AUTHOR]

ZrC whiskers were prepared on graphite through precursor transformation method. Effects of heat treatment temperature, catalyst concentration and heat treatment time on phase composition and microstructure of the ZrC whiskers were investigated. Growth mechanism of the ZrC whisker was analyzed. Results indicated that as heat treatment temperature increasing, catalyst activity increased and energy barrier for the carbothermal reduction reaction reduced, resulting in a gradual increase of both production and diameter of the ZrC whiskers. Catalyst could provide nucleation points for the ZrC whiskers, production and diameter of the ZrC whiskers firstly increased as the catalyst concentration increasing. While, when catalyst concentration was over high, length-diameter ratio of the ZrC whiskers decreased and some whiskers were agglomerated. Heat treatment time affected extent of the carbothermal reduction reaction. Production and length-diameter ratio of the ZrC whiskers increased firstly and then decreased with the increase of heat treatment time. When heat treatment temperature was 1600 °C, catalyst concentration was 0.4 mol/L, heat treatment time was 2 h, the ZrC whiskers with diameter of around 130 nm and length of tens of microns were synthesized. The whiskers were composed of a single-crystal ZrC core and an amorphous ZrO 2 shell. Growth of the ZrC whiskers was controlled by solid-liquid-solid (S-L-S) mechanism and the Ostwald ripening mechanism. [ABSTRACT FROM AUTHOR]

Crystallization via nucleation can isolate active pharmaceutical ingredients from their crudes. While chemical engineering textbooks provide theoretical knowledge on crystallization and nucleation theories, they often fall short in providing provide practical insights on the nucleation mechanism. To bridge this gap, we introduced a virtual experiment on nucleation in second-year chemical engineering classrooms. The main goal is to educate students on crystallization procedures in research and process industries, teaching them how to analyse and manage collected data while integrating theoretical knowledge. This includes conveying the kind of information that can be obtained from a crystallisation process and instructing students on how to analyse and manage the data collected in the light of the theories learned. We devised an original chemical engineering problem on nucleation, derived directly from the raw data collected in the classroom from virtual experiments. This method differs from the conventional approach of solving standard textbook problems. The textbook problems, regrettably often lack crucial information on how nucleation rate or surface free energy are directly obtained from raw data. By the conclusion of the virtual experiment, students have acquired a comprehensive understanding encompassing both practical and theoretical aspects of crystallization, with a particular focus on nucleation. The methodologies elucidated in this study can be applied across a spectrum of chemical engineering modules, including process engineering, unit operations in chemical engineering, mass transfer, and can even be integrated into specialized courses dedicated to crystallization. • Problems were developed in classroom based on experimental data from virtual lab. • Virtual experiments on nucleation deployed in third year chemical engineering classrooms. • Example problems on crystal nucleation developed in collaboration with students in the classroom. • Students solve the example problems developed by them in the classroom. [ABSTRACT FROM AUTHOR]

This study reports on the successful synthesis of Zn 2 P 2 O 7 glass using the conventional melt-quenching method. The state of the material has been investigated using X-ray Diffraction (XRD) and Differential Scanning Calorimetry (DSC), to verify its amorphous and glassy state with the onset of two distinct crystallization peaks. These peaks were indicative of the transition to α-Zn 2 P 2 O 7 and γ-Zn 2 P 2 O 7 phases during the annealing process, a finding that was supported by Fourier-transform infrared spectroscopy (FTIR) analysis. This marked the inaugural occasion where the stabilization of both Zn 2 P 2 O 7 phases from their respective annealed glassy state was achieved. The crystallization kinetics and associated parameters of Zn 2 P 2 O 7 glass were deeply delved into, with various models including Kissinger, Ozawa, and the Matusita-Sakka approach. The applied models elucidate the mechanisms of growth and nucleation within the glass matrix. This kinetic study provided valuable insights into the crystallization process, revealing that α-Zn 2 P 2 O 7 is both kinetically and thermally more stable than the γ-phase. However, it is less thermodynamically stable compared to the γ-phase. Besides, the study of phase transformations and crystallization kinetics was enhanced by the analysis of the Avrami index. [ABSTRACT FROM AUTHOR]

High-entropy carbides with tunable crystallization and growth have been demonstrated using single-source precursor derived ceramic route. The in situ nanocrystallization of high-entropy carbide phases, (Ta 0.2 W 0.2 V 0.2 Mo 0.2 Nb 0.2)Si δ C and (Ta 0.167 W 0.167 V 0.167 Mo 0.167 Nb 0.167 Si 0.167)C in amorphous Si-based ceramic matrices was achieved by using polysiloxanes and polycarbosilanes as polymer precursors respectively. The results exemplify a prominent role of the architectures of the polymeric precursors in controlling the structural features of these ceramics at various length scales. In particular, it was observed that high-entropy carbides with rock salt and zinc blende crystal structures were formed when polysiloxanes and polycarbosilanes with different backbone structure were used as polymeric precursors respectively. This is attributed to the thermodynamics of nucleation of the carbidic phases in these nanocomposites. Furthermore, the precursor architecture that dictates free carbon content, influenced nanostructural features and porosity in the material. Therefore, engineering such compositionally complex phases is feasible by selecting suitable polymeric precursors. • Precursor architecture influenced the crystal structure of high-entropy carbides. • Crystal structure dependent on earliest nucleated carbidic phase. • Free carbon played a key role in controlling crystallite size and porosity. [ABSTRACT FROM AUTHOR]

• Condensation positively affects the thrust of expanding flows in thrusters. • Increasing the inlet H 2 O 2 concentration decreases the liquefaction in the nozzles. • The nozzle length affects the non-equilibrium condensation in high-speed flows. • In the thruster nozzles, the nucleation continues until the nozzle outlet. Excessive flow expansion in the thruster nozzles reduces the flow temperature and pressure. This provides conditions for the condensation phenomena in the nozzle, which can affect the thrust performance of thrusters. In this paper, the condensation effect of water components in the decomposition products of hydrogen peroxide in a typical thruster nozzle is modeled. To describe the state and properties of the real gas mixture, the Peng-Robinson equation of state is used. Moreover, the effects of H 2 O 2 concentration and nozzle profile on the condensation and nozzle performance parameters are studied. The results show that by more flow expansion and crossing the saturated state of condensable components, the thrust coefficient improves up to 6%. This improvement decreases by increasing the H 2 O 2 concentration in the reaction chamber for a fixed nozzle expansion ratio. Due to the small growth of droplets during the free molecular regime of the droplet growth in the high-speed flow, the non-equilibrium condensation continues until the nozzle outflow. In addition, although all the profiles have the same expansion ratio for nucleation start, increasing the nozzle length results in larger nano-droplets, more liquid mass fraction formation up to 4%, and moving the Wilson point to the further upstream sections in the nozzle. [ABSTRACT FROM AUTHOR]

This study aimed to determine the nucleation mechanism, particle shape, and strengthening behavior of (Ti, Nb) (C, N) particles in Fe-based composite coatings. In this study, an in-situ technique combined with a plasma spray welding process was proposed to obtain a coating with in-situ (Ti, Nb) (C, N) particles. Composite coatings were successfully prepared on low-alloy steel by plasma spray welding using a mixture of Fe-based, Ti and Nb powders. N gas was used to provide the N atoms. The microstructural analysis results indicated that the reinforced particles transformed from irregular dendritic into massive and spherical particles, and then into spherical and lath particles, as the atomic ratio of Ti/Nb decreased. During solidification, TiN nucleated preferentially and Ti (C, N) particles were formed sequentially. Subsequently, NbC nucleated and grew with Ti (C, N) as its core, and (Ti, Nb) (C, N) particles were formed at the end. The microhardness values of these composite coatings were 680–970 HV, whereas that of low-alloy steel was 174 HV. The wear resistance of the composite coatings increased as the Ti/Nb atomic ratio decreased. The composite coating had the highest average microhardness and the best wear resistance when Ti/Nb = 1:3. Its average microhardness was five times more than that of the low-alloy steel. In addition, the mass loss of the composite coating was 0.4 mg, which is only one-sixth that of the low-alloy steel (2.4 mg). The main reason for this was the in-situ formation of (Ti, Nb) (C, N) particles, which were evenly distributed in the composite coatings. • The nucleation mechanism, particle shape, and strengthening behavior of the (Ti, Nb) (C, N) particles were investigated. • The problem of the uneven distribution of TiC or TiN in coatings was solved. • A reliable coating preparation method with a stable effect is provided. [ABSTRACT FROM AUTHOR]

[Display omitted] Nucleation underpins a vast range of phase-transition phenomena in many disciplines. Critical to revealing nucleation thermodynamics and kinetics is the understanding of the nucleus structure at its early stage. Typically, it is assumed that nucleation is a sudden local structural transition from one phase to another. Here, we are able to access fundamental steps in the nucleation from amorphous phase by a combination of molecular simulations and experimental observation. We discover a surprising pathway of semicrystalline nucleation where one of the materials components crystallizes and another remains amorphous between the crystalline planes in the nuclei. The early-stage crystallization nucleus is robustly evidenced to undergo a gradual ordering and densification, originating from the presence of diffuse interfaces, and renders an ultralow interfacial energy that is orders of magnitude lower than those typically used in various formulations of nucleation. Our study provides critical information and insight for the early stages of nucleation that determine how crystallization is initiated and benefits controllable synthesis of materials. [ABSTRACT FROM AUTHOR]

A novel precursor of 8YSZ nano-powders was precipitated from aqueous solutions using an antisolvent crystallization technique. Water was used as a solvent and ethanol was used as an antisolvent. During this experiment, the effect of initial concentration and mixing pattern on solid-state properties, such as microstructure particle size, agglomeration, and particle size distribution, of precursors and 8YSZ nano-powders were investigated. A series of analyses of as-obtained precursors and 8YSZ nano-powders showed that the lower initial concentration and injection mixing patterns, which provided a high supersaturation level and a stronger effect of ethanol as a dispersant, resulted in well-dispersed and small-sized powders. Further investigating the sintering and electrical properties of sintered 8YSZ ceramics, it was found that these properties were a strong function of particle sizes changed by various initial concentrations and mixing patterns. The density and conductivity of the sintered ceramics first increased and then decreased with the increasing particle size of 8YSZ nano-powders, which may be because of the as-obtained appropriate particle size (55–60 nm) from the optimal operating parameter (injection mixing patterns with high initial concentration) in favor of preventing grain coarsening in the sintering process. This work showed the potential to prepare the desired solid-state properties of 8YSZ nano-powders by changing operating parameters via an antisolvent crystallization technique. [ABSTRACT FROM AUTHOR]