Template For Nucleation Research Articles

Enhancing mechanical properties of carbonated steel slag through surfactant-assisted CaCO3 crystallization

This study investigates the enhancement of mechanical properties in carbonated steel slag through surfactant-assisted CaCO3 crystallization. Sodium dodecyl benzene sulfonate (SDBS) was employed at various concentrations (0.1–0.4 mol/L) and temperatures (20–60 °C) to modulate the carbonation process. Optimal performance was achieved with 0.2 mol/L SDBS at 40 °C, resulting in a maximum CO2 uptake of 8.51 % and a compressive strength of 62.89 MPa, 81.66 % higher than unmodified steel slag. Characterization techniques confirmed the formation of crystalline calcite, vaterite, and aragonite, contributing to improved microstructure and strength. SDBS micelles act as templates for CaCO3 nucleation and growth, with low concentrations facilitating carbonation and high concentrations inhibiting it. This research offers new insights into surfactant-assisted crystallization for enhancing carbonated steel slag properties, paving the way for high-performance, eco-friendly building materials from industrial waste.

Phase formation, structure and properties of quaternary MAX phase thin films in the Cr-V-C-Al system: A combinatorial study

Tailoring of individual atomic layers via alloying to synthesize quaternary MAX phases allows for expanding their chemical diversity and fine-tuning of their properties. In this study, Cr-V/C/Al multilayered precursors were deposited via combinatorial magnetron sputtering, creating nanostructured architectures with periodic stacking of nanolayers and varying Cr:V ratios. Their phase transformation and underlying reaction mechanisms during subsequent thermal annealing in argon towards the prospective quaternary solid solution (CrV)n+1AlCn MAX phases formation was systematically studied. Crystallization of (CrV)2AlC starts at approximately 500°C, while growth of higher-ordered (CrV)4AlC3 is observed from 960°C. Notably, intergrowth of (CrV)2AlC and (CrV)4AlC3 structures with coherent interface suggests that (CrV)2AlC acts as template for nucleation of (CrV)4AlC3. Thermal stability and high-temperature oxidation tests found that (CrV)2AlC exhibits higher thermal stability compared to (CrV)4AlC3 and films with Cr72.7V27.3 displayed good oxidation resistance at 1000°C, forming a protective bilayer oxide scale consisting of (Cr,Al)2O3 and Al2O3.

Effect of ultra-low dosage graphene oxide on the properties of recycled cement-based materials

The utilization of recycled fine powder (RFP) from crushed concrete waste as partial cement replacement is limited by its low reactivity. Graphene Oxide (GO) is a two-dimensional amphiphilic conjugated polymer that can effectively improve the properties of cement-based materials, but its application is limited due to its high cost. This study investigates the ultra-low dosage GO on the properties of recycled cement-based materials. GO was dispersed using polycarboxylate superplasticizers (PCE) before incorporation in the pastes containing 25 % RFP as the binder. The results show that PCE can effectively improve the dispersion of GO in cement-based materials. The improvement effect of well-dispersed ultra-low dosage GO on the strength of recycled cement-based materials in the early stage was better than that in the later stage, and the improvement effect on the flexural strength was better than that on the compressive strength. The GO dosage was optimized at 0.004 % which improved the 3 days flexural strength by 52 % compared to the control sample without GO. Results showed that well-dispersed ultra-low dosage GO accelerated the hydration of recycled cement-based materials due to the nucleation effect and template effect, promoted the formation of additional C–S–H gels, and facilitated the development of C–S–H gels more orderly, reduced the porosity of the hardened pastes, and refined the microstructure. However, excessive GO reduced strength due to agglomeration. The improvement in strength and microstructure refinement demonstrates the positive role of GO in enhancing the reactivity of recycled cement-based materials. This process successfully reduced the dosage of GO in cement-based materials by about 90 % and provided an approach to utilizing recycled fine powder.

Structure of the native γ-tubulin ring complex capping spindle microtubules

Microtubule (MT) filaments, composed of α/β-tubulin dimers, are fundamental to cellular architecture, function and organismal development. They are nucleated from MT organizing centers by the evolutionarily conserved γ-tubulin ring complex (γTuRC). However, the molecular mechanism of nucleation remains elusive. Here we used cryo-electron tomography to determine the structure of the native γTuRC capping the minus end of a MT in the context of enriched budding yeast spindles. In our structure, γTuRC presents a ring of γ-tubulin subunits to seed nucleation of exclusively 13-protofilament MTs, adopting an active closed conformation to function as a perfect geometric template for MT nucleation. Our cryo-electron tomography reconstruction revealed that a coiled-coil protein staples the first row of α/β-tubulin of the MT to alternating positions along the γ-tubulin ring of γTuRC. This positioning of α/β-tubulin onto γTuRC suggests a role for the coiled-coil protein in augmenting γTuRC-mediated MT nucleation. Based on our results, we describe a molecular model for budding yeast γTuRC activation and MT nucleation.

Structure of the γ-tubulin ring complex-capped microtubule.

Microtubules are composed of α-tubulin and β-tubulin dimers positioned head-to-tail to form protofilaments that associate laterally in varying numbers. It is not known how cellular microtubules assemble with the canonical 13-protofilament architecture, resulting in micrometer-scale α/β-tubulin tracks for intracellular transport that align with, rather than spiral along, the long axis of the filament. We report that the human ~2.3 MDa γ-tubulin ring complex (γ-TuRC), an essential regulator of microtubule formation that contains 14 γ-tubulins, selectively nucleates 13-protofilament microtubules. Cryogenic electron microscopy reconstructions of γ-TuRC-capped microtubule minus ends reveal the extensive intra-domain and inter-domain motions of γ-TuRC subunits that accommodate luminal bridge components and establish lateral and longitudinal interactions between γ-tubulins and α-tubulins. Our structures suggest that γ-TuRC, an inefficient nucleation template owing to its splayed conformation, can transform into a compacted cap at the microtubule minus end and set the lattice architecture of cellular microtubules.

Cr(VI) Reduction and Sequestration by FeS Nanoparticles Formed in situ as Aquifer Material Coating to Create a Regenerable Reactive Zone.

Remediation of large and dilute plumes of groundwater contaminated by oxidized pollutants such as chromate is a common and difficult challenge. Herein, we show that in situ formation of FeS nanoparticles (using dissolved Fe(II), S(-II), and natural organic matter as a nucleating template) results in uniform coating of aquifer material to create a regenerable reactive zone that mitigates Cr(VI) migration. Flow-through columns packed with quartz sand are amended first with an Fe2+ solution and then with a HS- solution to form a nano-FeS coating on the sand, which does not hinder permeability. This nano-FeS coating effectively reduces and immobilizes Cr(VI), forming Fe(III)-Cr(III) coprecipitates with negligible detachment from the sand grains. Preconditioning the sand with humic or fulvic acid (used as model natural organic matter (NOM)) further enhances Cr(VI) sequestration, as NOM provides additional binding sites of Fe2+ and mediates both nucleation and growth of FeS nanoparticles, as verified with spectroscopic and microscopic evidence. Reactivity can be easily replenished by repeating the procedures used to form the reactive coating. These findings demonstrate that such enhancement of attenuation capacity can be an effective option to mitigate Cr(VI) plume migration and exposure, particularly when tackling contaminant rebound post source remediation.

Stimuli-responsive graphdiyne-silver nanozymes for catalytic ion therapy of dental caries through targeted biofilms removal and remineralization

Clinical mechanical decontamination and irrigants are not consistently effective in preventing intractable biofilm-induced dental caries, especially when biofilms have caused demineralization. Constructing stimuli-responsive nanocatalysts with improved catalytic activity for plaque biofilm removal and remineralization enhancement remains challenging. Herein, a coordination-reduction strategy driven by L-cysteine and graphdiyne (GDY) is employed to anchor low-dose Ag nanoparticles/Ag+ to GDY nanosheets to obtain GDY/L-cys/Ag (GLA) nanozymes. Subsequently, biomimetic approach is used to encapsulate GLA into a GS ointment composed of gelatin methacryloyl and sodium alginate to form biodegradable and adhesive GLA/GS. GLA demonstrates acidic plaque biofilm-activated peroxidase-like activity, surpassing affinity toward H2O2 than natural horseradish peroxidase, effectively catalyzing low-dose H2O2 into highly toxic hydroxyl radicals (•OH). This catalytic activity simultaneously enhances Ag+ release triggered by acidic plaque biofilms, generating additional reactive oxygen species that can suppress plaque biofilms on ex vivo human teeth by the synergistic effect of catalysis and released ions. Importantly, GLA/GS serves as template nucleation sites crosslinked to rich Ca2+, thereby attracting PO43- from saliva, prompting growth into hydroxyapatite on tooth enamel, facilitating rapid remineralization. Due to the safe nanocatalytic ion therapy, in an in vivo rodent model, GLA/GS + H2O2 effectively prevents dental caries without influencing surrounding oral tissues.

Kinetic analysis and mechanism of nitrate, calcium, and cadmium removal using the newly isolated Pseudomonas sp. LYF26

The co-existence of heavy metals and nitrate (NO3−-N) pollutants in wastewater has been a persistent global concern for a long time. A strain LYF26, which can remove NO3−-N, calcium (Ca(II)), and cadmium (Cd(II)) simultaneously, was isolated to explore the properties and mechanisms of synergistic contaminants removal. Different conditions (Cd(II) and Ca(II) concentrations and pH) were optimized by Zero-, Half-, and First-order kinetic analyses to explore the environmental parameters for the optimal effect of strain LYF26. Results of the kinetic analyses revealed that the optimal culture conditions for strain LYF26 were pH of 6.5, Cd(II) and Ca(II) concentrations of 3.00 and 180.00 mg L−1, accompanied by Ca(II), Cd(II), and NO3−-N efficiencies of 53.10%, 90.03%, and 91.45%, respectively. The removal mechanisms of Cd(II) using strain LYF26 as a nucleation template were identified as biomineralization, lattice substitution, and co-precipitation. The differences and changes of dissolved organic matter during metabolism were analyzed and the results demonstrated that besides the involvement of extracellular polymeric substances in the precipitation of Cd(II) and Ca(II), the high content of humic acid-like species revealed a remarkable contribution to the denitrification process. This study is hopeful to contribute a theory for further developing microbially induced calcium precipitation used to treat complex polluted wastewater.

Elucidating the Bioinspired Synthesis Process of Magnetosomes-Like Fe3O4 Nanoparticles.

Iron oxide nanoparticles are a kind of important biomedical nanomaterials. Although their industrial-scale production can be realized by the conventional coprecipitation method, the controllability of their size and morphology remains a huge challenge. In this study, a kind of synthetic polypeptide Mms6-28 which mimics the magnetosome protein Mms6 is used for the bioinspired synthesis of Fe3O4 nanoparticles (NPs). Magnetosomes-like Fe3O4 NPs with uniform size, cubooctahedral shape, and smooth crystal surfaces are synthesized via a partial oxidation process. The Mms6-28 polypeptides play an important role by binding with iron ions and forming nucleation templates and are also preferably attached to the [100] and [111] crystal planes to induce the formation of uniform cubooctahedral Fe3O4 NPs. The continuous release and oxidation of Fe2+ from pre-formed Fe2+-rich precursors within the Mms6-28-based template make the reaction much controllable. The study affords new insights into the bioinspired- and bio-synthesis mechanism of magnetosomes.

Benzotrithiophene‐Based Covalent Organic Frameworks: Synthesis and Application to Perovskite Solar Cells

Two benzotrithiophene (BTT)‐based 2D covalent organic frameworks (2D COFs) are synthesized and characterized. The BTT and triphenylamine units (either tris(4‐aminophenyl)amine or N4,N4‐bis(4′‐amino‐[1,1′‐biphenyl]‐4‐yl)‐[1,1′‐biphenyl]‐4,4′‐diamine) are alternately connected for the two BTT‐based COFs, namely TABT–COF and BABT–COF, respectively. The obtained BTT‐based COFs exhibit high crystallinity, high surface area, and excellent thermal stability. In addition, these two COFs are further utilized as efficient additives by doping into the perovskite layer of perovskite solar cells (PSCs). The incorporation of BTT‐based COFs can be exploited as an efficient nucleation template, enabling the regulation of perovskite crystallinity. The power conversion efficiencies of the champion PSCs with TABT–COF and BABT–COF achieve 18.10% and 18.56%, respectively, outperforming that (16.58%) of the control device.

A Convergent fabrication of silk fibroin nanoparticles on quercetin loaded metal-organic frameworks for promising nanocarrier of myocardial infraction

The biomacromolecule silk fibroin (SF) may be constructed to promote biomimetic nucleation and nanostructures of inorganic nanomaterials, offering it a promising candidate for use in various biomimetic applications. We combined SF-NPs and ZIF-8-NPs to fabricate new drug vehicles that effectively release the drug. SF nanoparticles (SF-NPs) were assembled into quercetin (QCT), a myocardial drug added to fabricate QSF-NPs. By acting as a template for the ZIF-8 nucleation onto the surface, the QSF-NPs fabricated core-shell-structured nanocomposites (named QSF@Z-NCs) with ZIF-8 as the core-shell and the QSF-NPs. The biocompatibility analysis using the MTT assay revealed that the developed QCT, SF-NPs, and QSF@Z-NCs are not harmful to cardiac myoblast (H9C2) cells. The in vivo model demonstrated that H9C2 cells encouraged cardiomyocyte fibre regeneration in myocardial infarction rats. We fabricated a brand-new technique using H9C2 cells and QSF@Z-NCs that might encourage the healing processes in myocardial ischemia cells. This study's results demonstrate that it successfully treats myocardial injury.

Assessment of Triglyceride Droplet Crystallization Using Mixtures of β-Lactoglobulin and Phospholipids as Emulsifiers

Many applications in the life science and food industries require (semi-)crystalline oil-in-water (O/W) dispersions. Unfortunately, high supercooling and, thus, low temperatures are often needed to induce the crystallization of droplets. As low molecular weight emulsifiers (LMWEs) are able to act as nucleation templates, they might help to decrease the required level of supercooling. Furthermore, proteins and LMWEs are frequently co-formulated to improve the colloidal stability of emulsions and dispersions. Hence, choosing a suitable protein and LMWE mixture would allow for achieving specific product properties for controlling the solid fat content (SFC) and take advantage of the stabilization mechanisms of both emulsifiers. Therefore, this study focuses on the impact of the co-existence of β-lactoglobulin (β-lg) and phospholipids (PLs) LMWEs on the SFC of triglyceride (TAG) droplets at isothermal conditions using a thermo-optical method. When β-lg alone was used as an emulsifier, a maximum SFC of 80% was obtained at a supercooling of 32 K and 42 K for trilaurin and tripalmitin, respectively. The SFC could be increased to 100% using a PL containing saturated fatty acids (FAs) and a small hydrophilic headgroup. At the same supercooling, a PL containing saturated FAs and a large hydrophilic headgroup led to a maximum SFC of 80%. At lower supercooling, the SFC was reduced with this PL by 10% compared to β-lg alone. In addition, when the PLs had more time to adsorb and rearrange with ß-lg at the interface, even lower SFCs were observed compared to cooling directly after emulsification.

In-situ formation of heterogeneous interfaces inducing surface crystallographic manipulation toward highly stable Zn anode

The notorious dendrites and corrosion reactions mainly derive from the instability of interface kinetics in aqueous environments, prominently impeding the Zn anode in commercial applications. To circumvent this issue, we employed sodium methylenedinaphthalene disulphonate (SMD) to modulate interfacial deposition kinetics by forming heterogeneous interfaces containing the electrical double layer (EDL) and solid electrolyte interface (SEI) in different stages for achieving crystallographic optimization of Zn deposition and inhibiting parasitic reactions. Benefitting from the vital interplay between -S = O of SMD and Zn2+, as well as the adsorption privilege of SMD to water on the Zn anode, the EDL can assume functions of promoting the initial desolvation of Zn(H2O)62+ and uniformizing nucleation sites of Zn electroplating at the early stage, dedicated to the subsequent formation of compact SEI and Zn (002) preferential nucleation. Subsequently, the SMD-induced SEI interphase further steers the stratiform growth of the Zn (002) plane following the as-formed zinc seed nucleation template, realizing late-stage regulation of interfaces to deposition dynamics. As anticipated, utilizing SMD-contained electrolyte results in the Zn anode exhibiting remarkable stability for 1400 h under harsh conditions of 5 mA cm−2 and 3 mA h cm−2, facilitating the improvement of lifespan in Zn-MnO2 full cells during 1400 cycles. This work highlights the significance of interface regulation in reversible deposition dynamics and provides promising insights into stabilizing Zn anodes.

Preferential Ordering and Organization of Hydration Water Favor Nucleation of Ice by Ice-Nucleating Proteins over Antifreeze Proteins.

Bacteria containing ice-nucleating proteins (INPs) evolved in nature to nucleate ice at the high sub-zero ambiance. The ability of the INPs to induce order in the hydration layer and their aggregation propensity appear to be key factors of their ice nucleation abilities. However, the mechanism of the process of ice nucleation by INPs is yet to be understood clearly. Here, we have performed all-atom molecular dynamics simulations and analyzed the structure and dynamics of the hydration layer around the proposed ice-nucleating surface of a model INP. Results are compared with the hydration of a topologically similar non-ice-binding protein (non-IBP) and another ice-growth inhibitory antifreeze protein (sbwAFP). We observed that the hydration structure around the ice-nucleating surface of INP is highly ordered and the dynamics of the hydration water are slower, compared to the non-IBP. Even the ordering of the hydration layer is more evident around the ice-binding surface of INP, compared to the antifreeze protein sbwAFP. Particularly with increasing repeat units of INP, we observe an increased population of ice-like water. Interestingly, the distances between the hydroxyl groups of the threonine ladder and its associated channel water of the ice-binding surface (IBS) of INP in the X and Y direction mimic the oxygen atom distances of the basal plane of hexagonal ice. However, the structural synergies between the hydroxyl group distances of the threonine ladder and its associated channel water of the IBS of sbwAFP and oxygen atom distances of the basal plane are less evident. This difference makes the IBS of the INP a better template for ice nucleation than AFP, although both of them bind to the ice surface efficiently.

Bioinspired Matrix Vesicles Based on Platelet Membrane for Biomineralization of Dentin Tubules

Matrix vesicles (MVs), a kind of extracellular vesicles secreted by cells, play an important role in the initial stage of hard tissue mineralization. Acidic phospholipids and functional membrane proteins which are embedded into the membrane surface of MVs provide mineral nucleation sites and regulate mineral ions for facilitating biomineralization. Here, we report the MVs-mimic nanovesicles prepared from natural platelet membrane fragments. The bioinspired nanovesicles can penetrate into the deep dentinal tubule due to their stable nanostructure, and provide nucleation sites and templates for nascent mineral crystals. Meanwhile, the acidic phospholipids on the nanovesicle surface can recruit mineral ions from the environment to effectively promote biomineralization in situ. On the other hand, proteins on the surface of the nanovesicles can promote collagen cross-linking to inhibit the enzymatic hydrolysis of collagen, and further protect this mineralization template. The newly formed minerals can effectively seal the dentinal tubules, and even the sealing depth can reach 60 μm. This strategy uses “artificial MVs” derived from platelet membranes for the biomineralization of dentin, bringing new prospects for hard tissue repair in clinical practice.

Crystallinity Regulation and Defects Passivation for Efficient and Stable Perovskite Solar Cells Using Fully Conjugated Porous Aromatic Frameworks

AbstractFully conjugated porous aromatic frameworks (PAFs) have been constructed through Gilch reaction. The obtained PAFs have rigid conjugated backbones, high specific surface area, and excellent stability. The prepared PAF‐154 and PAF‐155 have been successfully applied in the perovskite solar cells (PSCs) by doping into the perovskite layer. The champion PSC devices afford a power conversion efficiency of 22.8 % and 22.4 %. It is found that the PAFs can be used as an efficient nucleation template, thus regulating the perovskite crystallinity. Meanwhile, PAFs can also passivate defects and promote carriers transporting in the perovskite film. By the comparative study with their linear counterpart, we unravel that the efficacy of PAFs is highly related to their porous structure and rigid fully conjugated networks. The unencapsulated devices with PAFs doping exhibit outstanding long‐term stability, retaining 80 % of their initial efficiencies after half‐year storage in ambient conditions.

Crystallinity Regulation and Defects Passivation for Efficient and Stable Perovskite Solar Cells Using Fully Conjugated Porous Aromatic Frameworks.

Fully conjugated porous aromatic frameworks (PAFs) have been constructed through Gilch reaction. The obtained PAFs have rigid conjugated backbones, high specific surface area, and excellent stability. The prepared PAF-154 and PAF-155 have been successfully applied in the perovskite solar cells (PSCs) by doping into the perovskite layer. The champion PSC devices afford a power conversion efficiency of 22.8% and 22.4%. It is found that the PAFs can be used as an efficient nucleation template, thus regulating the perovskite crystallinity. Meanwhile, PAFs can also passivate defects and promote carriers transporting in the perovskite film. By the comparative study with their linear counterpart, we unravel that the efficacy of PAFs is highly related to their porous structure and rigid fully conjugated networks. The unencapsulated devices with PAFs doping exhibit outstanding long-term stability, retaining 80% of their initial efficiencies after half-year storage in ambient conditions.

Microbially induced calcium precipitation driven by denitrification: Performance, metabolites, and molecular mechanisms

Microbially induced calcium precipitation (MICP) driven by denitrification has attracted extensive attention due to its application potential in nitrate removal from calcium-rich groundwater. However, little research has been conducted on this technique at the molecular level. Here, Pseudomonas WZ39 was used to explore the molecular mechanisms of nitrate-dependent MICP and the effects of Ca2+ on bacterial transcriptional regulation and metabolic response. The results exhibited that appropriate Ca2+ concentration (4.5 mM) can promote denitrification and the production of ATP, EPSs, and SMPs. Genome-wide analysis showed that the nitrate-dependent MICP was accomplished through heterotrophic denitrification and CO2 capture. During this process, EPS biosynthesis and Ca2+ signaling regulation were involved in the nucleation template supply and Ca2+ homeostasis balance. Untargeted transcriptome- and metabolome-association analyses revealed that the addition of Ca2+ triggered the significant up-regulation in several key pathways, such as transmembrane transporter and channel activities, amino acid metabolism, fatty acid biosynthesis, and carbon metabolism, which played a momentous role in the mineral nucleation and energy provision. The detailed information provided novel insights for understanding the active control of bacteria on MICP, and has great significance for deepening the cognition of groundwater remediation using nitrate-dependent MICP technique.

Interdependence between bacterial EPS and early grain coat development

AbstractBacteria are the most abundant forms of life we know on our planet, able to survive in a variety of habitats, that play an important role in mineral formation and transformation processes. Here, we present laboratory experiments in which unconsolidated quartz grains were seeded with Geobacter sulfurreducens cells and exposed to a mineral medium solution for 96 hours at temperatures of between 60°C and 120°C. Experimental data show the interdependence between extracellular polymeric substances (EPS) and the early formation of grain‐coating material. The occurrence of EPS promotes the development of web and bridging structures binding the quartz grains and creating EPS‐coated surfaces. With increasing temperature, an amorphous mineral phase grows preferentially on these surfaces suggesting that EPS can act as a template for mineral nucleation. At temperatures >100°C, the order of crystallinity of the amorphous authigenic phase increases, transitioning to poorly‐ordered rosette‐like textures.

In Situ Mineralizing Spinning of Strong and Tough Silk Fibers for Optical Waveguides.

Biopolymer-based optical waveguides with low-loss light guiding performance and good biocompatibility are highly desired for applications in biomedical photonic devices. Herein, we report the preparation of silk optical fiber waveguides through bioinspired in situ mineralizing spinning, which possess excellent mechanical properties and low light loss. Natural silk fibroin was used as the main precursor for the wet spinning of the regenerated silk fibroin (RSF) fibers. Calcium carbonate nanocrystals (CaCO3 NCs) were in situ grown in the RSF network and served as nucleation templates for mineralization during the spinning, leading to the formation of strong and tough fibers. CaCO3 NCs can guide the structure transformation of silk fibroin from random coils to β-sheets, contributing to enhanced mechanical properties. The tensile strength and toughness of the obtained fibers are up to 0.83 ± 0.15 GPa and 181.98 ± 52.42 MJ·m-3, obviously higher than those of natural silkworm silks and even comparable to spider silks. We further investigated the performance of the fibers as optical waveguides and observed a low light loss of 0.46 dB·cm-1, which is much lower than natural silk fibers. We believed that these silk-based fibers with excellent mechanical and light propagation properties are promising for applications in biomedical light imaging and therapy.