Isotropic liquid state of cocoa butter

The complex crystal structure of coca butter (CB) is responsible for the unique melting behavior, surface gloss, and mechanical properties of chocolate. While most studies concentrated on the crystalline state of CB, few studied the isotropic liquid state, which has a major impact on the crystallization process and the characteristics of the resulting crystals. In this study, the molecular organizations of the main CB triacylglycerols (TAGs; 1,3-dipalmitoyl-2-oleoylglycerol, palmitoyl-oleoyl-stearoylglycerol, POS, and 1,3-distearoyl-2-oleoylglycerol) were studied. The findings revealed the tunning-fork (Tf) conformation, commonly found in the crystalline state, is the least abundant in the isotropic liquid state of CB and pure TAGs. Notably, POS was found to interact with itself in CB, while its molecules with Tf conformation, although in small amounts in the mixture, tend to pair with each other at lower temperatures. These results highlight the significance of POS in CB crystallization and provide insights for developing CB alternatives.

Transplanted sagebrush "wildlings" exhibit higher survival than greenhouse-grown tubelings yet both recruit new plants

BACKGROUND

Land uses such as crop production, livestock grazing, mining, and urban development have contributed to degradation of drylands worldwide. Loss of big sagebrush (Artemisia tridentata) on disturbed drylands across the western U.S. has prompted massive efforts to re-establish this foundational species. There has been growing interest in avoiding the severe limitations experienced by plants at the seed and seedling stages by instead establishing plants from containerized greenhouse seedlings ("tubelings"). In some settings, a potential alternative approach is to transplant larger locally-collected plants ("wildlings"). We compared the establishment of mountain big sagebrush (A. tridentata ssp. vaseyana) from tubelings vs. wildlings in southeastern Idaho. A mix of native and non-native grass and forb species was drill-seeded in a pasture previously dominated by the introduced forage grass, smooth brome (Bromus inermis). We then established 80 m x 80 m treatment plots and planted sagebrush tubelings (n = 12 plots, 1200 plants) and wildlings (n = 12 plots, 1200 plants). We also established seeded plots (n = 12) and untreated control plots (n = 6) for long-term comparison. We tracked project expenses in order to calculate costs of using tubelings vs. wildlings as modified by probability of success.

RESULTS

There was high (79%) tubeling and low (10%) wildling mortality within the first year. Three years post-planting, chance of survival for wildlings was significantly higher than that of tubelings (85% and 14% respectively). Despite high up-front costs of planting wildlings, high survival rates resulted in their being < 50% of the cost of tubelings on a per-surviving plant basis. Additionally, by the third year post-planting 34% of surviving tubelings and 95% of surviving wildlings showed evidence of reproduction (presence / absence of flowering stems), and the two types of plantings recruited new plants via seed (3.7 and 2.4 plants, respectively, per surviving tubeling/wildling).

CONCLUSIONS

Our results indicate that larger plants with more developed root systems (wildlings) may be a promising avenue for increasing early establishment rates of sagebrush plants in restoration settings. Our results also illustrate the potential for tubelings and wildlings to improve restoration outcomes by "nucleating" the landscape via recruitment of new plants during ideal climate conditions.

Long term trends in source apportioned particle number concentrations in Rochester NY

During the past two decades, efforts have been made to further reduce particulate air pollution across New York State through various Federal and State policy implementations. Air quality has also been affected by economic drivers like the 2007-2009 recession and changing costs for different approaches to electricity generation. Prior work has focused on particulate matter with aerodynamic diameter ≤2.5 μm. However, there is also interest in the effects of ultrafine particles on health and the environment and analyses of changes in particle number concentrations (PNCs) are also of interest to assess the impacts of changing emissions. Particle number size distributions have been measured since 2005. Prior apportionments have been limited to seasonal analyses over a limited number of years because of software limitations. Thus, it has not been possible to perform trend analyses on the source-specific PNCs. Recent development have now permitted the analysis of larger data sets using Positive Matrix Factorization (PMF) including its diagnostics. Thus, this study separated and analyzed the hourly averaged size distributions from 2005 to 2019 into two data sets; October to March and April to September. Six factors were resolved for both data sets with sources identified as nucleation, traffic 1, traffic 2, fresh secondary inorganic aerosol (SIA), aged SIA, and O3-rich aerosol. The resulting source-specific PNCs were combined to provide continuous data sets and analyzed for trends. The trends were then examined with respect to the implementation of regulations and the timing of economic drivers. Nucleation was strongly reduced by the requirement of ultralow (<15 ppm) sulfur on-road diesel fuel in 2006. Secondary inorganic particles and O3-rich PNCs show strong summer peaks. Aged SIA was constant and then declined substantially in 2015 but rose in 2019. Traffic 1 and 2 have steadily declined bur rose in 2019.

Glass science behind lithium silicate glass-ceramics

OBJECTIVES

Lithium silicate-based glass ceramics have evolved as a paramount restorative material in restorative and prosthetic dentistry, exhibiting outstanding esthetic and mechanical performance. Along with subtractive machining techniques, this material class has conquered the market and satisfied the patients' needs for a long-lasting, excellent, and metal-free alternative for single tooth replacements and even smaller bridgework. Despite the popularity, not much is known about the material chemistry, microstructure and terminal behaviour.

METHODS

This article combines a set of own experimental data with extensive review of data from literature and other resources. Starting at manufacturer claims on unique selling propositions, properties, and microstructural features, the aim is to validate those claims, based on glass science. Deep knowledge is mandatory for understanding the microstructure evolution during the glass ceramic process.

RESULTS

Fundamental glass characteristics have been addressed, leading to formation of time-temperature-transformation (TTT) diagrams, which are the basis for kinetic description of the glass ceramic process. Nucleation and crystallization kinetics are outlined in this contribution as well as analytical methods to describe the crystalline fraction and composition qualitatively and quantitatively. In relation to microstructure, the mechanical performance of lithium silicate-based glass ceramics has been investigated with focus on fracture strength versus fracture toughness as relevant clinical predictors.

CONCLUSION

Fracture toughness has been found to be a stronger link to initially outlined manufacturer claims, and to more precisely match ISO recommendations for clinical indications.

Shear Histories Alter Local Shear Effects on Thrombus Nucleation and Growth

Our goal was to determine the impact of physiological and pathological shear histories on platelet nucleation and thrombus growth at various local shear rates. We designed and characterized a microfluidic device capable of subjecting platelets to shear histories reaching as high as 6700 s- 1 in a single passage. Time-lapse videos of platelets and thrombi are captured using fluorescence microscopy. Thrombi are tracked, and the degree of thrombosis is evaluated through surface coverage, platelet nucleation maps, and ensemble-averaged aggregate areas and intensities. Surface coverage rates were the lowest when platelets deposited at high shear rates following a pathological shear history and were highest at low shear rates following a pathological shear history. Early aggregate area growth rates were significantly larger for thrombi developing at high shear following physiological shear history than at high shear following a pathological shear history. Aggregate vertical growth was restricted when depositing at low shear following a pathological shear history. In contrast, thrombi grew faster vertically following physiological shear histories. These results show that physiological shear histories pose thrombotic risks via volumetric growth, and pathological shear histories drastically promote nucleation. These findings may inform region-based geometries for biomedical devices and refine thrombosis simulations.

Cryopreserved leukapheresis material can Be transferred from controlled rate freezers to ultracold storage at warmer temperatures without affecting downstream CAR-T cell culture performance and in-vitro functionality

Chimeric antigen receptor (CAR) T-cell therapies are increasingly adopted as a commercially available treatment for hematologic and solid tumor cancers. As CAR-T therapies reach more patients globally, the cryopreservation and banking of patients' leukapheresis materials is becoming imperative to accommodate intra/inter-national shipping logistical delays and provide greater manufacturing flexibility. This study aims to determine the optimal temperature range for transferring cryopreserved leukapheresis materials from two distinct types of controlled rate freezing systems, Liquid Nitrogen (LN2)-based and LN2-free Conduction Cooling-based, to the ultracold LN2 storage freezer (≤-135 °C), and its impact on CAR T-cell production and functionality. Presented findings demonstrate that there is no significant influence on CAR T-cell expansion, differentiation, or downstream in-vitro function when employing a transfer temperature range spanning from -30 °C to -80 °C for the LN2-based controlled rate freezers as well as for conduction cooling controlled rate freezers. Notably, CAR T-cells generated from cryopreserved leukapheresis materials using the conduction cooling controlled rate freezer exhibited suboptimal performance in certain donors at transfer temperatures lower than -60 °C, possibly due to the reduced cooling rate of lower than 1 °C/min and extended dwelling time needed to reach the final temperatures within these systems. This cohort of data suggests that there is a low risk to transfer cryopreserved leukapheresis materials at higher temperatures (between -30 °C and -60 °C) with good functional recovery using either controlled cooling system, and the cryopreserved materials are suitable to use as the starting material for autologous CAR T-cell therapies.

Impact of Membrane Phospholipids and Exosomes on the Kinetics of Amyloid-β Fibril Assembly

Alzheimer's disease (AD) is linked with the self-association of the amyloid-β peptide (Aβ) into oligomers and fibrils. The brain is a lipid rich environment for Aβ to assemble, while the brain membrane composition varies in an age dependent manner, we have therefore monitored the influence of lipid bilayer composition on the kinetics of Aβ40 fibril assembly. Using global-fitting models of fibril formation kinetics, we show that the microscopic rate constant for primary nucleation is influenced by variations in phospholipid composition. Anionic phospholipids and particularly those with smaller headgroups shorten fibril formation lag-times, while zwitterionic phospholipids tend to extend them. Using a physiological vesicle model, we show cellular derived exosomes accelerate Aβ40 and Aβ42 fibril formation. Two distinct effects are observed, the presence of even small amounts of any phospholipid will impact the slope of the fibril growth curve. While subsequent additions of phospholipids only affect primary nucleation with the associated change in lag-times. Heightened anionic phospholipids and cholesterol levels are associated with aging and AD respectively, both these membrane components strongly accelerate primary nucleation during Aβ assembly, making a link between disrupted lipid metabolism and Alzheimer's disease.

Toward exclusive stereocomplex crystallization of high-molecular-weight poly(L-lactic acid)/poly(D-lactic acid) blends with outstanding heat resistance via incorporating selective nucleating agents

In high molecular weight poly(L-lactic acid)/poly(D-lactic acid) (HMW PLLA/PDLA) blends, the construction of exclusive stereocomplex crystals (SC) with high crystallinity and strong melt memory remains a great challenge. In the present study, various norbornene dicarboxylate complexes (TMXNa, Mg, Al, or Ca) were employed as the stereo-selective nucleating agents (NAs), and their effect on the crystallization characteristics, rheological behavior, and heat resistance of PLLA/PDLA blends were thoroughly studied. Strikingly, TMX-Al facilitated the construction of exclusive SC with over 50 % crystallinity and excellent melt memory. The dense SC crystals network structure boosted the heat resistance of L/D-xAl blends with a VST as high as 145 °C. The strengthened intermolecular interaction fostered the generation of pre-ordered structure in the melt and enhanced chain interdiffusion, which contributed to intermolecular nucleation and SC crystallization in L/D-xAl blend. This study opens up a new avenue for melt processing and application development of SC-PLA materials.

Controlling Nucleation and Crystallization of CsPbI3 Perovskites for Efficient Inverted Solar Cells

The unfavorable morphology and high crystallization temperature (Tc ) of inorganic perovskites pose a significant challenge to their widespread application in photovoltaics. In this study, an effective approach is proposed to enhance the morphology of cesium lead triiodide (CsPbI3 ) while lowering its Tc . By introducing dimethylammonium acetate into the perovskite precursor solution, a rapid nucleation stage is facilitated, and significantly enhances the crystal growth of the intermediate phase at low annealing temperatures, followed by a slow crystal growth stage at higher annealing temperatures. This results in a uniform and dense morphology in CsPbI3 perovskite films with enhanced crystallinity, simultaneously reducing the Tc from 200 to 150 °C. Applying this approach in positive-intrinsic-negative (p-i-n) inverted cells yields a high power conversion efficiency of 19.23%. Importantly, these cells exhibit significantly enhanced stability, even under stress at 85 °C.

Investigation of lignin substructures participating in self-assembly for the synthesis of monodisperse lignin spherical particles

The intricate structure of lignin, characterized by a mix of hydrophilic components and hydrophobic structures from its aliphatic and aromatic constituents, poses challenges in creating monodisperse particles. This is due to the need for precise modulation of self-assembly kinetics. Herein, we explore a correlation between the substructure of lignin and its capacity for self-assembly. We have conducted an in-depth investigation into the interactions between hydrophilic groups, such as phenolic and aromatic-OH, and monolignols with interunit linkages that are involved in the formation of lignin particles (LPs). A high degree of hydrophilicity with a condensed structure is crucial for high supersaturation levels, which in turn determines the growth phase and leads to small LPs. An approach based on tailoring the supersaturation level which is contingent on the structural characteristics of extracted organosolv lignin was used to obtain remarkably uniform LPs with mean diameters of approximately 230 and 480 nm. The results of this study have the potential to serve as a foundation for the preparation of monodisperse LPs derived from various lignin sources as well as for the development of methods to extract lignin containing a specific chemical substructure.

Identifying Ice-Binding Proteins in Nature

Organisms inhabiting freezing terrestrial, polar, and alpine environments survive because they have evolved adaptations to tolerate sub-freezing temperatures. Among these adaptations are ice-binding proteins (IBPs) which in the case of fishes and some insects have antifreeze properties which allow them to avoid freezing even at their lowest environmental temperatures. Other organisms, including some insects, microorganisms, and plants, tolerate freezing and also contain IBPs. Unlike fish and insects, their antifreeze properties (hysteresis) are minimal, but most are potent ice recrystallization inhibitors (IRIs). Microbes secrete IBPs into their immediate environment where they are thought to modify ice growth in a way that ensures a liquidous habitat in the ice and also reduces ice recrystallization. With plants, IBPs are found in the small amount of apoplastic fluid associated with the extracellular spaces and show a weak hysteresis but are potent IRIs.Techniques are described for drawing blood and hemolymph from fish and insects, respectively, in order to determine whether there is a hysteresis present (separation of the freezing and melting points) indicative of an antifreeze protein. For microbes, which secrete very small amounts of IBPs into their environment, a technique is described where their spent growth media causes the pitting of the basal plane of an ice crystal at a temperature slightly below the media freezing point. In plants, IBPs are isolated from the apoplastic fluids of the leaves by vacuum infiltration of a fluid into the extracellular spaces and then recovering the fluid by centrifugation.The pitting of the basal plane again can be used to verify the presence of IBPs in the concentrated apoplastic fluid.The techniques describe how to collect fluids from a variety of organisms to determine if IBPs are present using nanoliter osmometry or using the ice basal plane pitting technique.

Mineral scaling induced membrane wetting in membrane distillation for water treatment: Fundamental mechanism and mitigation strategies

The scaling-induced wetting phenomenon seriously affects the application of membrane distillation (MD) technology in hypersaline wastewater treatment. Unlike the large amount of researches on membrane scaling and membrane wetting, scaling-induced wetting is not sufficiently studied. In this work, the current research evolvement of scaling-induced wetting in MD was systematically summarized. Firstly, the theories involving scaling-induced wetting were discussed, including evaluation of scaling potential of specific solutions, classical and non-classical crystal nucleation and growth theories, observation and evolution of scaling-induced processes. Secondly, the primary pretreatment methods for alleviating scaling-induced wetting were discussed in detail, focusing on adding agents composed of coagulation, precipitation, oxidation, adsorption and scale inhibitors, filtration including granular filtration, membrane filtration and mesh filtration and application of external fields including sound, light, heat, electromagnetism, magnetism and aeration. Then, the roles of operation conditions and cleaning conditions in alleviating scaling-induced wetting were evaluated. The main operation parameters included temperature, flow rate, pressure, ultrasound, vibration and aeration, while different types of cleaning reagents, cleaning frequency and a series of assisted cleaning measures were summarized. Finally, the challenges and future needs in the application of nucleation theory to scaling-induced wetting, the speculation, monitoring and mitigation of scaling-induced wetting were proposed.

Nucleation by a charged particle in fluids containing salt

We present a model to describe ion-induced nucleation in fluids. Nucleation is induced by a charged molecular aggregate, a large ion, a charged colloid, or an aerosol particle. This model generalizes the Thomson model to polar environments. Solving the Poisson-Boltzmann equation, we find the potential profiles around the charged core and calculate the energy. Our results are analytical in the Debye-Hückel limit and numerical otherwise. From the Gibbs free energy curve vs. nucleus size, we find the metastable and stable states and the energy barrier between them, for varying saturation values, core's charge, and amount of salt. The nucleation barrier decreases with increasing core charge or Debye length. We calculate the phase lines in the phase diagram of supersaturation and core charge. We find regions of one phase, electro-prewetting, spontaneous nucleation, ion-induced nucleation, and classical-like nucleation.

Insight into biomolecular interaction-based non-classical crystallization of bacterial biocement

In an attempt to draw a correlation between calcium carbonate (CaCO3) precipitation and biomacromolecules such as extracellular polymeric substances and enzyme activity in biomineralizing microbe, this report aims to elucidate the ureolytic and ammonification route in Paenibacillus alkaliterrae to explore the possible role of organic biomolecule(s) present on cell surface in mediating nucleation and crystallization of biogenic CaCO3. After 168 h of biomineralization in ureolysis and ammonification, 2.2 g/l and 0.87 g/l of CaCO3 precipitates were obtained, respectively. The highest carbonic anhydrase activity (31.8 µmoles/min/ml) was evidenced in ammonification as opposed to ureolysis (24.8 µmoles/min/ml). Highest urease activity reached up to 9.26 µmoles/min/ml in ureolytic pathway. Extracellular polymeric substances such as polysaccharides and proteins were found to have a vital role not only in the nucleation and crystal growth but also in addition direct polymorphic fate of CaCO3 nanoparticles. EPS production was higher during ammonification (3.1 mg/ml) than in ureolysis (0.72 mg/ml). CaCO3 nanoparticle-associated proteins were found to be 0.82 mg/ml in ureolysis and 0.56 mg/ml in ammonification. After 30 days of biomineralization, all the polymorphic forms stabilized to calcite in ureolysis but in ammonification vaterite predominated. In our study, we showed that organic template-mediated prokaryotic biomineralization follows the non-classical nucleation and varying proportions of these organic components causes selective polymorphism of CaCO3 nanoparticles. Overall, the findings are expected to further the fundamental understanding of enzymes, EPS-driven non-classical nucleation of CaCO3, and we foresee the design of fit-for-purpose futuristic biominerals arising from such renewed understanding of biomineralization. KEY POINTS: • Organic-inorganic interface of cell surface promote crystallization of biominerals • Carbohydrate and proteins in the interface results selective polymorphism of CaCO3 • Calcite stabilized at 30 days in ureolysis, vaterite-calcite mix in ammonification.

Advanced imaging techniques for studying protein phase separation in living cells and at single-molecule level

Protein-protein and protein-RNA interactions are essential for cell function and survival. These interactions facilitate the formation of ribonucleoprotein complexes and biomolecular condensates via phase separation. Such assembly is involved in transcription, splicing, translation and stress response. When dysregulated, proteins and RNA can undergo irreversible aggregation which can be cytotoxic and pathogenic. Despite technical advances in investigating biomolecular condensates, achieving the necessary spatiotemporal resolution to deduce the parameters that govern their assembly and behavior has been challenging. Many laboratories have applied advanced microscopy methods for imaging condensates. For example, single molecule imaging methods have enabled the detection of RNA-protein interaction, protein-protein interaction, protein conformational dynamics, and diffusional motion of molecules that report on the intrinsic molecular interactions underlying liquid-liquid phase separation. This review will outline advances in both microscopy and spectroscopy techniques which allow single molecule detection and imaging, and how these techniques can be used to probe unique aspects of biomolecular condensates.

Controversies on the mechanism and kinetics of emulsion polymerization: An updated critical review

Conventional emulsion polymerization (EP) is a process via free radicals whose driving force for its development has been its versatility to generate polymer colloids with ad hoc characteristics for a wide variety of applications, as well as its friendly character to the environment since the continuous medium is water. Although through decades of research, considerable progress has been made in understanding its mechanism and kinetics, some aspects are still not entirely clear. Furthermore, new ideas and experimental results have appeared in the literature that challenge the accepted knowledge about some aspects of EP. This work is a personal vision and an updated critical review on those controversial aspects whose precedent is the review with the same approach published by the author and collaborators almost 20 years ago (J. Macromol. Sci. Part C Polym. Rev., 2004;44:207-229). This review covers advances, aspects that are open to discussion or need improvement regarding what happens in the aqueous phase and in the interface (initiator decomposition, entry and exit of radicals, monomer transport) as well as in the polymer particles (free-radical propagation and termination, swelling, average number of radicals per particle). Special attention is paid to particle formation (nucleation) and its interrelation with colloidal stability and the evolution of the particle size distribution (PSD), which is one of the most fundamental and controversial issues of EP. The Smoluchowski collision rate coefficient to describe diffusion-controlled processes has practically become a paradigm despite the fact that there is evidence that questions its applicability. For this reason, this review also emphasizes this point and the alternatives that have been proposed to mathematically describe the diffusive stages of particle coagulation, the entry of radicals, and the termination reaction. Challenges in improving our understanding of the mechanism and kinetics of emulsion polymerization are pointed out.

A Deeper Understanding of Metal Nucleation and Growth in Rechargeable Metal Batteries Through Theory and Experiment

Lithium and sodium metal batteries continue to occupy the forefront of battery research. Their exceptionally high energy density and nominal voltages are highly attractive for cutting-edge energy storage applications. Anode-free metal batteries are also coming into the research spotlight offering improved safety and even higher energy densities than conventional metal batteries. However, uneven metal nucleation and growth which leads to dendrites continues to limit the commercialisation of conventional and anode-free metal batteries alike. This review connects models and theories from well-established fields in metallurgy and electrodeposition to both conventional and anode-free metal batteries. These highly applicable models and theories explain the driving forces of uneven metal growth and can inform future experiment design. Finally, the models and theories that are most relevant to each anode-related cell component are identified. Keeping these specific models and theories in mind will assist with rational design for these components.

Nucleation of naturally occurring calcic amphibole asbestos

This article proposes an initial model of natural asbestiform minerals growing in four stages. Structures dating from the early stages of the development were observed in the damaged zone surrounding meso-fractures, more particularly in microfractures, microcavities and microcracks that lie in front of and along mesofractures. This study is limited to calcium amphiboles cross-fibers, which develop from altered calcium amphiboles. The observations were made using PLM, with some using TEM. The samples are amphibolites, dolerites and skarns from France. All these rocks have in common that they have been exposed to hydrothermal circulation which gives them a propylite character. The earliest phenomenon was the development of metasomatic veins. In these veins, actinolite form pseudomorphs after hornblendes. The new amphiboles preserve the original morphology of hornblende, in particular the appearance of the cleavages. In the second stage, hydrothermal Fluid circulation promotes the development of subgrains (DSG) with boundaries generally parallel to the cleavage. Some sub-grains become thinner and more and more individualized due to dissolution by the hydrothermal fluid. The third stage is fracturing. The irregular ends of DSGs and amphibole debris can form the substrate of asbestiform mineral nuclei. Further dissolution of DSGs can also lead to the creation of substrates. The last stage is the nucleation and growth. The nuclei have a conical shape and variable widths, from a few microns to about ten microns. The basal parts of the asbestos minerals (BPAMs) extend the DSGs along the c axis. BPAMs have variable widths and can divide during their development at the level of transverse microcracks. BPAMs when not dividing have a morphology comparable to that of whisker nanocrystals synthesized using the vapor-liquid-crystal mechanism. The shape of the fragments from BPMAs is close to that of DSGs as both have variable widths and both have lengths controlled by microcracks.

Crystallization inhibitory effects of konjac glucomannan, sodium alginate and xanthan gum on curcumin in supersaturated solution

Supersaturating drug delivery system (SDDS) is a promising approach to enhance the solubility of hydrophobic functional components. However, SDDS is thermodynamically unstable and crystallization tends to occur. In this work, curcumin was used as a model compound, and the crystallization inhibitory effect of konjac glucomannan (KGM), sodium alginate (SA) and xanthan gum (XTG) on curcumin in supersaturated solution was investigated. Amorphous solubility of curcumin was determined using ultraviolet extinction, fluorescence spectroscopy and dynamic light scattering methods. Nucleation induction time (NIT) and crystal growth rate of curcumin were evaluated using ultraviolet probe in the absence and presence of various natural polysaccharides (NPs). Results showed that amorphous solubility of curcumin was approximately 30 μg/mL in pH 6.8 phosphate buffer. NPs used in this work restrained nucleation or crystal growth of curcumin effectively. The NITs of curcumin in the absence of NPs and in the presence of XTG, KGM and SA (1 μg/mL) were 3.7, 60.7, 20.0 and 8.0 min, respectively. The crystal growth rate of curcumin in the absence of NPs and in the presence of XTG, SA and KGM (1 μg/mL) were 0.0103, 0.00752, 0.00286 and 0.000306 min^-1, respectively. The nucleation inhibitory effect of NPs on curcumin was ranked as XTG > KGM > SA. The order of crystal growth inhibition capacity of NPs was KGM > SA > XTG. In conclusion, NPs could be incorporated into SDDS to maintain supersaturation of hydrophobic components for enhanced bioavailability.

Fiber support prevents colloid-facilitated contamination induced by dissolution-precipitation of a calcium phosphate adsorbent

During the adsorptive removal of hazardous metal contaminants, dissolution-precipitation of sparingly soluble adsorbents may result in the formation of toxic colloidal suspensions, triggering secondary pollution. Therefore, we studied the prevention of colloid-facilitated contamination in a model adsorption system of dicalcium phosphate dihydrate (DCPD, CaHPO₄·2H₂O) and Cd²⁺ as an adsorbent and adsorbate. Upon adding pure DCPD powder into a 500 mg L^-1 Cd²⁺ solution of pH ≌ 7.0, aggregates of spheroidal Cd-bearing primary particles, within 0.040-0.95 μm size range, were generated via dissolution-precipitation. The accumulated volume of these submicron particles (10.8%) was greater than that of the submicron particles from the exposure of DCPD to deionized water (4.48%). While the Cd-carrying submicron particles, which are responsible for colloidal recontamination, appeared to form via homogeneous nucleation, their formation was suppressed using polyacrylonitrile fibers (PANFs) as supporting substrates. Thus, heterogeneous nucleation on PANFs formed hexagonal columnar microparticles of a new phase, pentacadmium dihydrogen tetrakis (phosphate) tetrahydrate (Cd₅H₂(PO₄)₄·4H₂O). Together with dissolution-precipitation on the native DCPD, nucleation and growth on the PANFs accelerated the depletion of the dissolved species, reducing the degree of supersaturation along the DCPD-water interface. Although the PANFs decreased the Cd adsorption capacity to 56.7% of that of DCPD, they prevented the formation of small aggregates of Cd-bearing particles. Other sparingly soluble adsorbents can be compounded with PANF to prevent the generation of toxic colloids.

Small molecules interfacial assembly regulate the crystallization transition process for nobiletin stabilization

Many bioactive nutraceuticals naturally occurring in food materials possess beneficial biological activities, while their use as functional supplements is subjected to hydrophobicity and crystallinity. Currently, inhibiting crystallization for such nutrients is of immense scientific interest. Here, we exploited diverse structural polyphenols as potential inhibitors for restraining Nobiletin crystallization. Specifically, the crystallization transition process could be influenced by the polyphenol gallol density, Nobiletin supersaturation (1, 1.5, 2, 2.5 mM), temperature (4, 10, 15, 25 and 37 ℃), and pH (3.5, 4, 4.5, 5), important factors for regulating the binding attachment and interactions. The optimized samples could be guided by NT100 lied in 4 ℃ at pH 4. Besides, the main assembly driving force was hydrogen-bonding cooperated with π-π stacking and electrostatic interaction, leading to a Nobiletin/TA combination ratio of ∼ 3:1. Our findings proposed an innovative synergistic strategy for inhibiting crystallization and broaden potential applications of polyphenol-based materials in advanced biological fields.

Role of silk nanocrystal (SNC)-ZnO as an antibacterial nucleating nanohybrid for a patterned mimic poly(lactic acid) based nanofabric

This new investigation deals with the synthesis of an organic-inorganic nanohybrid using SNC with magnificent flower bud-shaped ZnO, termed SNC-ZnO by precipitation method. The nanohybrid (with concentrations 1 wt%, 3 wt%, and 5 wt%) was in situ incorporated into the PLA matrix to prepare the electrospun solution. The functionalized PLA composite nanofibres produced by electrospinning with SNC-ZnO nanohybrid were systematically studied using different structural and morphological analyses to meet the challenging processing requirements. The FESEM analysis gives an average diameter of nanofibres 246 ± 10.2 nm where nanohybrid tends to adhere on the surface of the PLA nanofabric increasing hydrophobicity up to water contact angle 135.3 ± 0.25 °C with 5 wt% nanohybrid incorporation. The nanofabric has significant antibacterial activity against E.Coli and S.Aureus bacteria. Further, an extensive study has been made on thermally stipulated processes using DSC on non-isothermal crystallization kinetics using different models: Avrami, Ozawa, Mo, and Tobin. The results revealed sites for heterogeneous nucleation and improvement in crystallinity, t_1/2, and nucleation effects due to the incorporation of crystalline nanohybrid in PLA nanofibres. Further, the Avrami plot has confirmed both primary and secondary crystallization processes thereby considering its potential to utilize functionalized PLA nanofabric for applications in protective textile.

Sodium citrate increases the aggregation capacity of calcium ions during microbial mineralization to accelerate the formation of calcium carbonate

The microbially induced carbonate precipitation (MICP) technique is widely used in soil heavy metal pollution control. Microbial mineralization involves extended mineralization times and slow crystallization rates. Thus, it is important to discover a method to accelerate mineralization. In this study, we selected six nucleating agents to screen and investigated the mineralization mechanism using polarized light microscopy, scanning electron microscopy, X-ray diffraction and Fourier-transform infrared spectroscopy. The results showed that sodium citrate removed 90.1% Pb better than traditional MICP and generated the highest amount of precipitation. Interestingly, due to the addition of sodium citrate (NaCit), the rate of crystallization increased and vaterite was stabilized. Moreover, we constructed a possible model to explain that NaCit increases the aggregation capacity of calcium ions during microbial mineralization to accelerate the formation of calcium carbonate (CaCO₃). Thus, sodium citrate can increase the rate of MICP bioremediation, which is important for improving MICP efficiency.

Effect of ultrasonic-induced selenium crystallization behavior during selenium reduction

In this work, the crystallization process of selenium was accelerated by ultrasonic wave. The effects of ultrasonic waves and conventional conditions of selenium crystallization were compared to understand the effects of different conditions on crystallization, including ultrasonic time, ultrasonic power, reduction temperature, and H2SeO3 concentration. The mechanism of ultrasound affecting selenium crystallization was also investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The experimental results showed that ultrasonic time, ultrasonic power, and reduction temperature significantly influenced the crystallization process and morphology of selenium. Ultrasonic time had a large effect on the completeness (all products have been crystallized) and integrity of the crystallization of the products. Meanwhile, ultrasonic power and reduction temperature had no effect on the completeness of crystallization. However, it had a significant effect on the morphology and integrity of the crystallized products, and different morphologies of the nano-selenium materials could be obtained by changing the ultrasonic parameters. Both primary and secondary nucleation are important in the process of ultrasound-accelerated selenium crystallization. The cavitation effect and mechanical fluctuant effects generated by ultrasound could reduce the crystallization induction time and accelerate the primary nucleation rate. The high-speed micro-jet formed in the rupture of the cavitation bubble generated is the most important reason to influence the secondary nucleation of the system.

Soft Tissue Aberration Correction for Histotripsy Using Acoustic Emissions From Cavitation Cloud Nucleation and Collapse

OBJECTIVE

Phase aberration from soft tissue limits the efficacy of histotripsy, a therapeutic ultrasound technique based on acoustic cavitation. Previous work has shown that the acoustic emissions from cavitation can serve as "point sources" for aberration correction (AC). This study compared the efficacy of soft tissue AC for histotripsy using acoustic cavitation emissions (ACE) from bubble cloud nucleation and collapse.

METHODS

A 750-kHz, receive-capable histotripsy array was pulsed to generate cavitation in ex vivo porcine liver through an intervening abdominal wall. Received ACE signals were used to determine the arrival time differences to the focus and compute corrective delays. Corrections from single pulses and from the median of multiple pulses were tested.

DISCUSSION

On average, ACE AC obtained 96% ± 3% of the pressure amplitude obtained by hydrophone-based correction (compared with 71% ± 5% without AC). Both nucleation- and collapse-based corrections obtained >96% of the hydrophone-corrected pressure when using medians of ≥10 pulses. When using single-pulse corrections, nucleation obtained a range of 49%-99% of the hydrophone-corrected pressure, while collapse obtained 95%-99%.

CONCLUSION

The results suggest that (i) ACE AC can recover nearly all pressure amplitude lost owing to soft tissue aberration and that (ii) the collapse signal permits robust AC using a small number of pulses.

Effect of applied potential on the optical and electrical properties of Cu2CoO3

The effect of the applied potential on the crystallography, morphology, optical, and electrical properties of copper-cobalt oxide (Cu₂CoO₃) co-electrodeposited on ITO (Indium Tin Oxide) substrate has been studied. The electrochemical behavior of Cu₂CoO₃ using cyclic voltammetry showed that the co-electrodeposition of Cu₂CoO₃ occurred at a negative potential of - 0.70 V versus SCE, following a quasi-reversible reaction controlled by the diffusion process. Chronoamperometry (CA) revealed that the nucleation and growth mechanism of Cu₂CoO₃ follows the instantaneous three-dimensional process according to Scharifker and Hill model. X-ray diffraction (XRD) analysis indicated that the resulting layers at different applied potentials exhibited an orthorhombic structure with a preferred orientation of the crystallites (011) plan. The morphology of the surface changes with potential applied. Furthermore, the optical properties of the copper and cobalt oxide films were investigated using UV-visible spectroscopy; showing that the band gap energy for all the materials increases when the applied potential decreases. The Cu₂CoO₃ layers obtained are p-type semiconductors. The acceptor density (N_A) increases with decreasing applied potential.

The temperature dependent dynamics and periodicity of dropwise condensation on surfaces with wetting heterogeneities

HYPOTHESIS

Biphilic surfaces, namely surfaces comprising hydrophilic areas with a (super)hydrophobic background, are used in nature and engineering for controlled dropwise condensation and liquid transport. These, however, are highly dependent on the surface temperature and subcooling.

EXPERIMENTS

Here, biphilic surfaces were cooled inside a rotatable environmental chamber under controlled humidity. The condensation dynamics on the surface was quantified, depending on the subcooling, and compared to uniform superhydrophobic (USH) surfaces. Rates of condensation and transport were analyzed in terms of droplet number and size, covered area and fluid volume over several length scales. Specifically, from microscale condensation to macroscale droplet roll-off.

FINDINGS

Four phases of condensation were identified: a) initial nucleation, b) droplets on single patches, c) droplets covering adjacent patches and d) multi-patch droplets. Only the latter become mobile and roll off the surface. Cooling the surface to temperatures between T = 2-16 °C shows that lowering the temperature shortens some of the condensation parameters linearly, while others follow a power law, as expected from the theory of condensation. The temperature dependent condensation dynamics on (super)biphilic surfaces is faster in comparison to uniform superhydrophobic surfaces. Nevertheless, within time intervals of a few hours, droplets are mostly immobile. This sets guiding lines for using biphilic surfaces in applications such as water collection, heat transfer and separation processes. Generally, biphilic surfaces are suitable for applications in which fluids should be collected, concentrated and immobilized in specific areas.

Nucleation and growth of ZnTe thin layers electrodeposited on ITO substrate

In order to develop materials able to guarantee optimal characteristics in terms of environmental compatibility, abundance, and photoactivity, zinc telluride (ZnTe) has become a great candidate for optoelectronic and photovoltaic device applications. In this work, on the basis of electrochemical techniques including cyclic voltammetry and chronoamperometry, it was found that the electrodeposition of zinc telluride (ZnTe) on indium tin oxide substrate (ITO) is a quasi-reversible reaction controlled by the diffusion process. The nucleation and growth mechanism follows the instantaneous three-dimensional process according to Scharifker and Hill model. The crystallographic structure and film morphology were studied by XRD and SEM analyses, respectively. ZnTe films have a cubic crystal structure, and they are characterized by good homogeneity. The optical measurements of the deposited films were performed, and a direct energy gap of 2.39 eV was determined by UV-visible spectroscopy.

Seed-mediated strategy for synthesis of enzyme-encapsulated metal-organic frameworks with enhanced enzyme activity

Encapsulation of enzymes into metal-organic frameworks (enzyme@MOF) can improve the stability of enzymes. Most present synthesis methods of enzyme@MOF rely on the complex modification of enzymes or the natural negative surface charge of enzymes to promote the synthesis of enzyme@MOF. Despite extensive efforts, it remains challenging to develop a surface charge-independent and convenient strategy to encapsulate various enzymes into MOF efficiently. In this study, we proposed a convenient seed-mediated strategy for efficient synthesis of enzyme@MOF from the perspective of MOF formation. The seed, acting as nuclei, makes the slow nucleation stage skipped, leading to the efficient synthesis of enzyme@MOF. The successful encapsulation of several proteins demonstrated the feasibility and advantages of the seed-mediated strategy. Moreover, the resulting composite, cytochrome (Cyt c) encapsulated in ZIF-8, exhibited a 5.6-fold increase in bioactivity compared to free Cyt c. The seed-mediated strategy provides an efficient, enzyme surface charge-independent, and non-modified method for the synthesis of enzyme@MOF biomaterials, which warrants further exploration and application in diverse fields.

The adsorption of single Au atom and nucleation on γ-Al2O3 surfaces

Single-atom catalysts (SACs) in heterogeneous catalysts have attracted increasing attention and the adsorption and nucleation of single atom on the surface are closely related to the performance of the catalyst. The present work employed density functional theory calculations to examine the adsorption of single Au atom and nucleation on γ-Al₂O₃ surfaces at the atomic level. The effect of surface hydroxyls group on the adsorption and nucleation of single Au atom on γ-Al₂O₃ surfaces is explored. It was found that the spillover reactions of surface hydroxyls H atoms with the deposited Au_- are not available on the hydroxylated surface. The interaction of Au to the clean surface is the stronger than to the hydroxylated surface. The even-odd alternations of Au_x and weak binding of single Au atoms to γ-Al₂O₃ leads to large even-numbered Au cluster on the surface. Density of states and electron density difference analysis show that the electronic structure of Au/γ-Al₂O₃ is quite different from the reported Cu and Pd on Al₂O₃.

Detection and Analysis of Microtubule Nucleator γ-Tubulin Ring Complex

Golgi-derived microtubules constitute an asymmetrical microtubule network that drives polarized transport of vesicles to support cell polarization and directional migration. Golgi-based microtubule nucleation requires the γ-tubulin ring complex (γTuRC), the principal microtubule nucleator in animal cells. In this chapter, we present methods for detecting γTuRC components and associated proteins on the Golgi, examining Golgi-based microtubule nucleation, and measuring the microtubule-nucleating activity of isolated γTuRCs. These approaches have been demonstrated to be effective for assessing the microtubule-organizing function of the Golgi complex.

Control strategies of ice nucleation, growth, and recrystallization for cryopreservation

The cryopreservation of biomaterials is fundamental to modern biotechnology and biomedicine, but the biggest challenge is the formation of ice, resulting in fatal cryoinjury to biomaterials. To date, abundant ice control strategies have been utilized to inhibit ice formation and thus improve cryopreservation efficiency. This review focuses on the mechanisms of existing control strategies regulating ice formation and the corresponding applications to biomaterial cryopreservation, which are of guiding significance for the development of ice control strategies. Herein, basics related to biomaterial cryopreservation are introduced first. Then, the theoretical bases of ice nucleation, growth, and recrystallization are presented, from which the key factors affecting each process are analyzed, respectively. Ice nucleation is mainly affected by melting temperature, interfacial tension, shape factor, and kinetic prefactor, and ice growth is mainly affected by solution viscosity and cooling/warming rate, while ice recrystallization is inhibited by adsorption or diffusion mechanisms. Furthermore, the corresponding research methods and specific control strategies for each process are summarized. The review ends with an outlook of the current challenges and future perspectives in cryopreservation. STATEMENT OF SIGNIFICANCE: Ice formation is the major limitation of cryopreservation, which causes fatal cryoinjury to cryopreserved biomaterials. This review focuses on the three processes related to ice formation, called nucleation, growth, and recrystallization. The theoretical models, key influencing factors, research methods and corresponding ice control strategies of each process are summarized and discussed, respectively. The systematic introduction on mechanisms and control strategies of ice formation is instructive for the cryopreservation development.

Single-Molecule Fluorescence Methods to Study Protein-RNA Interactions Underlying Biomolecular Condensates

Many biomolecular condensates, including nucleoli and stress granules, form via dynamic multivalent protein-protein and protein-RNA interactions. These molecular interactions nucleate liquid-liquid phase separation (LLPS) and determine condensate properties, such as size and fluidity. Here, we outline the experimental procedures for single-molecule fluorescence experiments to probe protein-RNA interactions underlying LLPS. The experiments include single-molecule Förster (Fluorescence) resonance energy transfer (smFRET) to monitor protein-induced conformational changes in the RNA, protein-induced fluorescence enhancement (PIFE) to measure protein-RNA encounters, and single-molecule nucleation experiments to quantify the association and buildup of proteins on a nucleating RNA. Together, these experiments provide complementary approaches to elucidate a molecular view of the protein-RNA interactions that drive ribonucleoprotein condensate formation.

Modulation of bioactive calcium phosphate micro/nanoparticle size and shape during in situ synthesis of photo-crosslinkable gelatin methacryloyl based nanocomposite hydrogels for 3D bioprinting and tissue engineering

Background

The gelatin-methacryloyl (GelMA) polymer suffers shape fidelity and structural stability issues during 3D bioprinting for bone tissue engineering while homogeneous mixing of reinforcing nanoparticles is always under debate.

Method

In this study, amorphous calcium phosphates micro/nanoparticles (CNP) incorporated GelMA is synthesized by developing specific sites for gelatin structure-based nucleation and stabilization in a one-pot processing. The process ensures homogenous distribution of CNPs while different concentrations of gelatin control their growth and morphologies. After micro/nanoparticles synthesis in the gelatin matrix, methacrylation is carried out to prepare homogeneously distributed CNP-reinforced gelatin methacryloyl (CNP GelMA) polymer. After synthesis of CNP and CNP GelMA gel, the properties of photo-crosslinked 3D bioprinting scaffolds were compared with those of the conventionally fabricated ones.

Results

The shape (spindle to spherical) and size (1.753 μm to 296 nm) of the micro/nanoparticles in the GelMA matrix are modulated by adjusting the gelatin concentrations during the synthesis. UV cross-linked CNP GelMA (using Irgacure 2955) has significantly improved mechanical (three times compressive strength), 3D printability (160 layers, 2 cm self-standing 3D printed height) and biological properties (cell supportiveness with osteogenic differentiation). The photo-crosslinking becomes faster due to better methacrylation, facilitating continuous 3D bioprinting or printing.

Conclusion

For 3D bioprinting using GelMA like photo cross-linkable polymers, where structural stability and homogeneous control of nanoparticles are major concerns, CNP GelMA is beneficial for even bone tissue regeneration within short period.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s40824-022-00301-6.

Formation of extremely low-volatility organic compounds from styrene ozonolysis: Implication for nucleation

Styrene is a highly reactive compound with the dual nature of aromatics and olefins. This work presents evidence for formation of extremely low-volatility organic compounds (ELVOCs) from styrene ozonolysis. The molecules of ELVOCs were analyzed using a high-resolution orbitrap mass spectrometer. The results show that ELVOCs were oligomers characterized by stabilized Criegee radicals (SCIs) as chain units. The addition of C₆H₅CHOO (SCI1) or CH₂OO (SCI2) can dramatically decrease the oligomers' volatility. At low relative humidity (RH), ELVOCs are mainly formed from the reaction of RO₂ radical, C₆H₅OO·, with SCI1 and SCI2; however, ELVOCs are primarily produced by the reaction between benzoic acid and SCI1 at high RH. Ambient particles were also collected to propose the probable oligomers from styrene-SCI. Our results suggest that styrene-SCI derived ELVOCs may act as nucleating agents, potentially providing an experimental basis for nucleation events that frequently occur in urban areas.

New opportunities for sustainable bioplastic development: Tailorable polymorphic and three-phase crystallization of stereocomplex polylactide by layered double hydroxide

Stereocomplexation between enantiomeric poly(l-lactide) (PLLA) and poly(d-lactide) (PDLA) is a promising sustainable approach and gaining momentum to overcome the shortcomings of polylactide (PLA) for its use as a replacement for fossil-based plastics. Filler addition in tailoring the crystallization of stereocomplex PLA (SC-PLA) attracts extensive attention; however, research has primarily focused on the heterogeneous nucleation effect of filler. The impact of filler on the chain behavior of SC-PLA during crystallization has not been exclusively discussed, and the rigid amorphous fraction (RAF) development remains unknown. In this study, the crystallization of PLLA/PDLA blends was modified by low loading of layered double hydroxide (LDH) (≤ 1 wt%) with the proposed local effect of such filler, and additional RAF development was incurred. In the early stage of crystallization, LDH facilitates the pairing of PLLA and PDLA and arrests the ordered SC pairs during the dynamic balance between the separation and pairing of racemic segments. This explains the severely suppressed homochiral (HC) crystallization, promoted SC crystallization, and additional RAF formation driven by the nucleation-induced chain ordering. This work, for the first time, highlights the role of LDH in creating SC-PLA with tailorable polymorphism and RAF, where the mechanism can be extended to other filler-type nucleator systems.

H2S release rate strongly affects particle size and settling performance of metal sulfides in acidic wastewater: The role of homogeneous and heterogeneous nucleation

Sulfide precipitation is an extensively used method to precipitate metal and arsenic from acidic wastewater, whereas the tiny and negatively-charged metal sulfides with poor settling performance are generated. The factors and mechanisms that influence particle size and settling performance remain unclear. Herein, the effects of sulfuration factors, e.g., reagent dosage, acidity and H₂S release rate on the particle size and settling performance of metal sulfides were investigated, and involved mechanisms were systematically revealed. The results showed that the reagent dosage and acidity had a limited effect on particle size and settling performance while the H₂S release rate played a critical role. Under homogeneous conditions, the decrease in H₂S release rate, which can reduce the initial supersaturation and supply the sustainable supersaturation, increased the particle size of metal sulfides generated using Na₂S solution. Under heterogeneous conditions, the decrease in H₂S release rate further increased the particle size of metal sulfides generated using low-solubility CaS/FeS and further improved settling performance, in which heterogeneous nucleation played a crucial role besides supersaturation. The developed dissolution-diffusion-growth model qualitatively explained the negative relationship between H₂S release rate and particle growth. This work provides implications for improving the settling performance of metal sulfides in acidic wastewater.

Starch crystal seed tailors starch recrystallization for slowing starch digestion

Crystal seed significantly affected polymers homogeneous or heterogeneous crystallization. However, how starch crystal seed affected recrystallization of gelatinized starch and in turn digestibility were not clearly understood. Herein, effects of endogenous crystal seed on starch recrystallization and digestibility were herein investigated. Structures of retrograded starches characterized by Fourier transform infrared spectroscopy and X-ray diffraction indicated that endogenous A-type crystal seed significantly promoted starch reassociation to form well-defined crystalline structure. Notably, starch crystal seed-mediated retrograded starch contained more compact structures after cooking in comparison with that of retrograded starch mediation without the crystal seed, and therefore the crystal seed-mediated retrograded starch exhibited a lower digestibility. This study preliminarily indicated starch endogenous crystal seed significantly modulate starch retrogradation and digestibility, nevertheless, how recrystallization temperature, the content and crystalline structure of the crystal seed affect recrystallization behaviors of crystal seed-containing starch are part of future work.

Competition Between Heterogeneous Nucleation and Flow-Induced Crystallization of Polyamide 66 and its Carbon Nanotube Composites

Both heterogeneous nucleation and flow-induced entropy reduction are the two well-known factors that accelerate polymer crystallization. However, the interplay of nucleation and flow-induced acceleration is still poorly understood. This work investigates the nucleating effect of carbon nanotubes (CNT) on both the quiescent and flow-induced crystallization kinetics of polyamide 66 (PA 66). The quiescent crystallization study indicates that CNT acts as a powerful nucleant, as suggested by the fact that the critical cooling rate to bypass crystallization and create the amorphous glassy state changes from 1,000 K/s in PA 66 neat resin to a rate faster than 4,000 K/s in the PA 66 nanocomposites. The flow-induced crystallization study indicates PA 66 onset crystallization time and morphology depend on the shear work introduced by rotational rheometry. A combined acceleration effect from CNT nucleants and flow-induced crystallization (FIC) persists when the CNT loading is under the saturation limit. However, if CNT loading meets the saturation limit, specific shear work shows no impact on the crystallization time, providing evidence that the role of the FIC acceleration effect no longer exists when nucleant acceleration dominates the crystallization of PA 66. This article is protected by copyright. All rights reserved.

Sulfate mineral scaling: From fundamental mechanisms to control strategies

Sulfate scaling, as insoluble inorganic sulfate deposits, can cause serious operational problems in various industries, such as blockage of membrane pores and subsurface media and impairment of equipment functionality. There is limited article to bridge sulfate formation mechanisms with field scaling control practice. This article reviews the molecular-level interfacial reactions and thermodynamic basis controlling homogeneous and heterogeneous sulfate mineral nucleation and growth through classical and non-classical pathways. Common sulfate scaling control strategies were also reviewed, including pretreatment, chemical inhibition and surface modification. Furthermore, efforts were made to link the fundamental theories with industrial scale control practices. Effects of common inhibitors on different steps of sulfate formation pathways (i.e., ion pair and cluster formation, nucleation, and growth) were thoroughly discussed. Surface modifications to industrial facilities and membrane units were clarified as controlling either the deposition of homogeneous precipitates or the heterogeneous nucleation. Future research directions in terms of optimizing sulfate chemical inhibitor design and improving surface modifications are also discussed. This article aims to keep the readers abreast of the latest development in mechanistic understanding and control strategies of sulfate scale formation and to bridge knowledge developed in interfacial chemistry with engineering practice.

Lysozyme crystallization in hydrogel media under ultrasound irradiation

Sonocrystallization implies the application of ultrasound radiation to control the nucleation and crystal growth depending on the actuation time and intensity. Its application allows to induce nucleation at lower supersaturations than required under standard conditions. Although extended in inorganic and organic crystallization, it has been scarcely explored in protein crystallization. Now, that industrial protein crystallization is gaining momentum, the interest on new ways to control protein nucleation and crystal growth is advancing. In this work we present the development of a novel ultrasound bioreactor to study its influence on protein crystallization in agarose gel. Gel media minimize convention currents and sedimentation, favoring a more homogeneous and stable conditions to study the effect of an externally generated low energy ultrasonic irradiation on protein crystallization avoiding other undesired effects such as temperature increase, introduction of surfaces which induce nucleation, destructive cavitation phenomena, etc. In-depth statistical analysis of the results has shown that the impact of ultrasound in gel media on crystal size populations are statistically significant and reproducible.

Interplay between crosslinking and ice nucleation controls the porous structure of freeze-dried hydrogel scaffolds

Freeze-drying is a process of choice to texture hydrogel scaffolds with pores formed by an ice-templating mechanism. Using state-of-the-art microscopies (cryo-EBSD, μCT, CLSM), this work evidences and quantifies the effect of crosslinking and ice nucleation temperature on the porous structure of thin hydrogel scaffolds freeze-dried at a low cooling rate. We focused on a polysaccharide-based hydrogel and developed specific protocols to monitor or trigger ice nucleation for this study. At a fixed number of intermolecular crosslinks per primary molecule (p = 5), the mean pore size in the dry state decreases linearly from 240 to 170 μm, when ice nucleation temperature decreases from -6 °C to -18 °C. When ice nucleation temperature is fixed at -10 °C, the mean pore size decreases from 250 to 150 μm, as the crosslinking degree increases from p = 3 to p = 7. Scaffold infiltration ability was quantified with synthetic microspheres. The seeding efficiency was assessed with MC3T3-E1 individual cells and HepaRG™ spheroids. These data collapse into a single master curve that exhibits a sharp transition from 100 % to 0 %-efficiency as the entity diameter approaches the mean pore size in the dry state. Altogether, we can thus precisely tune the porosity of these 3D materials of interest for 3D cell culture and cGMP production for tissue engineering.

Mechanisms of nuclei growth in ultrasound bubble nucleation

This paper interrogates the intersections between bubble dynamics and classical nucleation theory (CNT) towards constructing a model that describes intermediary nucleation events between the extrema of cavitation and boiling. We employ Zeldovich's hydrodynamic approach to obtain a description of bubble nuclei that grow simultaneously via hydrodynamic excitation by the acoustic field and vapour transport. By quantifying the relative dominance of both mechanisms, it is then possible to discern the extent to which viscosity, inertia, surface tension and vapour transport shape the growth of bubble nuclei through non-dimensional numbers that naturally arise within the theory. The first non-dimensional number Φ₁²/Φ₂ is analogous to the Laplace number, representing the balance between surface tension and inertial constraints to viscous effects. The second non-dimensional number δ represents how enthalpy transport into the bubble can reduce nucleation rates by cooling the surrounding liquid. This formulation adds to the current understanding of ultrasound bubble nucleation by accounting for bubble dynamics during nucleation, quantifying the physical distinctions between "boiling" and "cavitation" bubbles through non-dimensional parameters, and outlining the characteristic timescales of nucleation according to the growth mechanism of bubbles throughout the histotripsy temperature range. We observed in our simulations that viscous effects control the process of ultrasound nucleation in water-like media throughout the 0-120 °C temperature range, although this dominance decreases with increasing temperatures. Enthalpy transport was found to reduce nucleation rates for increasing temperatures. This effect becomes significant at temperatures above 30 °C and favours the creation of fewer nuclei that are larger in size. Conversely, negligible enthalpy transport at lower temperatures can enable the nucleation of dense clusters of small nuclei, such as cavitation clouds. We find that nuclei growth as modelled by the Rayleigh-Plesset equation occurs over shorter timescales than as modelled by vapour-dominated growth. This suggests that the first stage of bubble nuclei growth is hydrodynamic, and vapour transport effects can only be observed over longer timescales. Finally, we propose that this framework can be used for comparison between different experiments in bubble nucleation, towards standardisation and dosimetry of protocols.

Biobased nucleation agents for poly-L-(lactic acid) - Effect on crystallization, rheological and mechanical properties

In the present work, the nucleating aptitude for poly-L-(lactic acid) (PLLA) of several biobased nanoparticles (NPs) with different morphologies and surface properties, including cellulose nanofibrils with and without lignin (LCNFs and CNFs) as well as cellulose, chitin and starch nanocrystals (CNCs, ChNCs and SNCs), was investigated. A single melt-processing step using a small amount of poly(ethylene glycol) (PEG) as carrier for the NPs was adopted to prepare films with the same nanofiller content of 1 wt%. The nucleation efficiency was investigated by differential scanning calorimetry using Avrami's and Lauritzen-Hoffman's secondary nucleation theory. The crystallization half-time was found to change considerably according to the morphology and surface properties of the NPs, with the lowest time observed for CNFs and CNCs, followed by ChNCs, SNCs and LCNFs. Comparing the surface energy components of the different nucleating agents, it was found that the nanofiller with the highest γ^p had the lowest t_1/2 and demonstrated the most effective nucleating aptitude. The evolution of the melt rheological properties of the different compositions, and the mechanical and optical properties of the films with and without a short annealing treatment were also studied.

Improvements in chitosan-based slurry ice production and its application in precooling and storage of Pampus argenteus

The effects of microbubbles in chitosan-based slurry ice production were investigated, and the efficiency of chitosan-based slurry ice was evaluated for silver pomfret (Pampus argenteus) precooling and storage at 0 °C. Microbubbles generated though agitation accelerated slurry ice production by promoting ice nucleation and eliminating supercooling. Higher bubble counts improved freezing, but overly large bubbles reduced the performance. The rheological properties of chitosan solutions were also investigaed, and solutions with higher viscosity formed more bubbles. Experiments investigating precooling rates, microbial concentrations, pH, thiobarbituric-acid-reactive substances, and total volatile basic nitrogen all confirmed that chitosan-based slurry ice had higher performance than flake ice or conventional slurry ice. Chitosan-based slurry ice can be used for precooling in the fish industry to reduce energy consumption, accelerate precooling, reduce microbial growth, and improve shelf life.

Nucleation increases the visual appeal of lager but does not alter overall likeability or drinking rate

BACKGROUND

Glassware can be an effective vehicle to recruit customers, revive brands, build profits and increase alcohol consumption by capitalising on the immediacy of glassware to the point of consumption. The design of glassware can also contribute to harm reduction by slowing and reducing consumption. Nucleated bases have been added to lager glasses in recent years which allow carbon dioxide (CO₂) to be more rapidly released and ascend through the solution. The aim of these studies was to investigate the effect of nucleated glasses on the likeability and drinking rate of lager in alcohol drinkers.

METHODS

In Study 1, participants (n = 116) were asked to taste two glasses of lager (280 millilitres (ml) each) in separate 5-min taste tests and fill out a likeability questionnaire after each glass in a within-subjects design with one factor of glass (nucleated, non-nucleated). The primary outcome was the likeability of lager and the secondary outcome was volume consumption during taste tests. In Study 2, participants (n = 160) were asked to consume a pint of lager (568 ml) and fill out a likeability questionnaire in a between-subjects design with one factor of glass (nucleated, non-nucleated). The primary outcome was time taken to consume a pint of lager and secondary outcomes were the likeability of lager, mood and alcohol craving.

RESULTS

There was no clear evidence that likeability of lager differed between nucleated and non-nucleated glasses in either study. In Study 1, a paired-samples t test found strong evidence that lager in nucleated glasses was more visually appealing (single item from likeability measure) than lager in non-nucleated glasses (mean difference (MD) = 10.2, 95% confidence interval (CI) 6.1, 14.2, p < 0.001). In Study 2, a linear regression found no clear evidence that lager was consumed at different rates from nucleated and non-nucleated glasses (nucleated: 16.9 min, non-nucleated: 16.3 min, MD: 0.6 min, 95% CI - 1.5, 2.7, p = 0.57).

CONCLUSIONS

Nucleated lager glasses do not appear to alter the likeability or consumption (volume consumed in Study 1 or drinking rate in Study 2) of lager, although they do seem to increase the visual appeal and refreshment of lager. This may increase the number of drinking episodes by making the drinking experience more enjoyable which may lead to increased alcohol related harm.

Accelerating the Crystallization of Zeolite SSZ-13 with Polyamines

Tailoring processes of nucleation and growth to achieve desired material properties is a pervasive challenge in synthetic crystallization. In systems where crystals form via nonclassical pathways, engineering materials often requires the controlled assembly and structural evolution of colloidal precursors. In this study, we examine zeolite SSZ-13 crystallization and show that several polyquaternary amines function as efficient accelerants of nucleation, and, in selected cases, tune crystal size by orders of magnitude. Among the additives tested, polydiallyldimethylammonium (PDDA) was found to have the most pronounced impact on the kinetics of SSZ-13 formation, leading to a 4-fold reduction in crystallization time. Our findings also reveal that enhanced nucleation occurs at an optimal PDDA concentration where a combination of light-scattering techniques demonstrate these conditions lead to polymer-induced aggregation of amorphous precursors and the promotion of (alumino)silicate precipitation from the growth solution. Here, we show that relatively low concentrations of polymer additives can be used in unique ways to dramatically enhance SSZ-13 crystallization rates, thereby improving the overall efficiency of zeolite synthesis.

Crystallization of microbial polyhydroxyalkanoates: A review

Polyhydroxyalkanoates (PHAs), produced by the microbial fermentation, is a promising green polymer and has attracted much attention due to its excellent biocompatibility, complete biodegradability, and non-cytotoxicity. The physical properties of PHAs are closely related to their chemical and crystalline structure. Therefore, deep understanding and regulating the structure and crystallization of PHAs are the key factors to improve the performance of PHAs. This review first provides a brief overview of the development history, chemical structure, and basic properties of PHAs. Then, the crystal structure, crystal morphology, kinetics theories and crystallization behavior of nucleation-induced PHAs are systematically summarized to provide a theoretical foundation for improving PHAs crystallization rate and physical properties. In the end, the outlook on the crystallization and application prospects of PHAs is also addressed.

De novo protein folding on computers. Benefits and challenges

There has been recent success in prediction of the three-dimensional folded native structures of proteins, most famously by the AlphaFold Algorithm running on Google's/Alphabet's DeepMind computer. However, this largely involves machine learning of protein structures and is not a de novo protein structure prediction method for predicting three-dimensional structures from amino acid residue sequences. A de novo approach would be based almost entirely on general principles of energy and entropy that govern protein folding energetics, and importantly do so without the use of the amino acid sequences and structural features of other proteins. Most consider that problem as still unsolved even though it has occupied leading scientists for decades. Many consider that it remains one of the major outstanding issues in modern science. There is crucial continuing help from experimental findings on protein unfolding and refolding in the laboratory, but only to a limited extent because many researchers consider that the speed by which real proteins folds themselves, often from milliseconds to minutes, is itself still not fully understood. This is unfortunate, because a practical solution to the problem would probably have a major effect on personalized medicine, the pharmaceutical industry, biotechnology, and nanotechnology, including for example "smaller" tasks such as better modeling of flexible "unfolded" regions of the SARS-COV-2 spike glycoprotein when interacting with its cell receptor, antibodies, and therapeutic agents. Some important ideas from earlier studies are given before moving on to lessons from periodic and aperiodic crystals, and a possible role for quantum phenomena. The conclusion is that better computation of entropy should be the priority, though that is presented guardedly.

Revealing the roles of polymers in supersaturation stabilization from the perspective of crystallization behaviors: A case of nimodipine

Formulating drugs into amorphous solid dispersions (ASDs) represents an attractive means to enhance the aqueous solubility of drugs. Furthermore, water-soluble polymers have proven highly advantageous for stabilizing supersaturated solutions of ASDs. However, the performance and mechanism of various polymers in stabilizing supersaturated drug solutions have not been well-studied. The aim of this study was to investigate the effects of different commercial polymers on the dissolution behaviors and supersaturation stabilization of the ASDs and to further explore the mechanism of polymer mediated supersaturation maintenance by studying the crystallization behaviors of the ASDs. In this study, nimodipine (NMD) was used as a model drug because of its poor water-solubility and fast crystallization rate in aqueous solution, and three polymers polyvinylpyrrolidone (PVP), vinylpyrrolidone-vinyl acetate copolymer (PVP VA), and polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft co-polymer (Soluplus) was selected as the drug carriers to form the ASDs with NMD. Solid-state characterizations of the ASDs confirmed the amorphous state of the ASD systems. ASD_{PVP VA} demonstrated superior supersaturation maintenance in dissolution experiments compared to the other two ASD systems. Among the polymers tested, PVP VA most efficiently maintained dissolution of NMD and prevented its crystallization from the supersaturated solution. The ability of PVP VA to most-effectively maintain supersaturation of the drug was manifested by inhibition of crystal nucleation rather than inhibition of crystal growth following nucleation. These results suggest that nucleation inhibition was instrumental in enabling the polymer-mediated supersaturation maintenance, at least with NMD.