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Monolayer protected metal clusters comprise a rich class of molecular systems and are promising candidate materials for a variety of applications. While a growing number of protected nanoclusters have been synthesized and characterized in crystalline forms, their dynamical behavior in solution, including prenucleation cluster formation, is not well understood due to limitations both in characterization and first-principles modeling techniques. Recent advancements in machine-learned interatomic potentials are rapidly enabling the study of complex interactions such as dynamical behavior and reactivity on the nanoscale. Here, we develop an Au-S-C-H atomic cluster expansion (ACE) interatomic potential for efficient and accurate molecular dynamics simulations of thiolate-protected gold nanoclusters (Aun(SCH3)m). Trained on more than 30,000 density functional theory calculations of gold nanoclusters, the interatomic potential exhibits ab initio level accuracy in energies and forces and replicates nanocluster dynamics including thermal vibration and chiral inversion. Long dynamics simulations (up to 0.1 μs time scale) reveal a mechanism explaining the thermal instability of neutral Au25(SR)18 clusters. Specifically, we observe multiple stages of isomerization of the Au25(SR)18 cluster, including a chiral isomer. Additionally, we simulate coalescence of two Au25(SR)18 clusters and observe series of clusters where the formation mechanisms are critically mediated by ligand exchange in the form of [Au-S]n rings.

This study presents the interfacial behaviour of benzoylated cellulose of different wettability from melon and moringa pods waste using Pickering emulsions systems. The benzoylated cellulose was prepared in an aqueous alkaline medium using benzoyl chloride as a modifying agent and characterized by X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy and scanning electron microscopy (SEM). The X-ray diffraction showed that crystallinity of cellulose from moringa and melon are 67.47 and 70.20%, respectively. The functionalized derivatives are thermally stable than the native counterpart. The SEM revealed that isolated cellulose suffered surface degradation upon functionalization as a result of the repeated collision between reactants. The wetting properties of the cellulose can be controlled by using different quantities of modifying agents, and the emulsions stability depend on the wettability of the emulsifiers. The higher stability recorded for the emulsions stabilized by benzoylated cellulose from moringa pod waste revealed that cellulose wettability depends on the sources. [ABSTRACT FROM AUTHOR]

The main purpose of this article is to model an industrial spiral-type gravitational coalescer by applying population balance as the governing equation. In this model, considering the two-dimensional movement of crude oil flow in the coalescer, the mechanisms of differential sedimentation, laminar shear, and Brownian motion are considered to determine the collision rate of droplets. Then, the population balance equation was solved to determine the droplet size distribution, dehydration, and desalination efficiency using the class method. The simulation results were in good match with the gathered industrial data. Finally, the influence of interfacial tension of water and oil, the pressure drop of the mixing valve, oil temperature, oil density, and washing water flow rate on the process efficiency was analyzed. The modeling results indicated that increasing the interfacial tension of water and oil from 30 to 36 mN/m and the oil density from 800 to 900 kg/m3 will decrease the water removal efficiency by 4.35% and 14.18%, respectively. Also, increasing the temperature of oil from 300 to 340 K and the volume fraction of washing water from 3% to 15% improves the efficiency of separating water from crude oil by 9.55% and 9.95%, respectively. [ABSTRACT FROM AUTHOR]

Coalescence event in pendant and sessile droplets is distinguished by the formation and evolution of the liquid bridge created upon singular contact. For Newtonian droplets, the bridge radius, R , is known to evolve as R ∼ t b , with universal values of the power-law exponent, b , signifying the dominant governing forces. However, recent works on different subclasses of rheologically complex fluids comprising of macromolecules have highlighted the effects of additional forces on coalescence. In this work, we experimentally explore the phenomenon in distinct subclasses of rheologically complex fluids, namely, colloidal and noncolloidal suspensions, that have particle hydrodynamic interactions as the origin of viscoelasticity. Our observations suggest that such fluids have flow-dependent thinning responses with finite elasticity in shear rheology but negligible elasticity in extensional rheology. Based on these, the study extends the Newtonian universality of b = 0.5 to these thinning fluids. Further, we fortify these observations through a theoretical model developed by employing Ostwald–de Waele's constitutive law. Finally, we utilize this theoretical model to inspect the existence of arrested coalescence in generalized Newtonian fluids. [ABSTRACT FROM AUTHOR]

Cameron et al. (2010) and Fruehwald & Gorman (2011) present the pattern of homorganic consonant cluster reduction in Catalan as a challenge to Baković’s (2005) theory of antigemination, which predicts that any feature ignored in the determination of consonant identity for the purposes of antigemination in a given language must independently assimilate in that language. I argue that the pattern in Catalan is not a counterexample to this prediction if the reduction process is analyzed as coalescence, following Wheeler (2005), rather than as deletion.

In this study,polytetrafluoroethylene(PTFE), a commonly used coalescence oil removal material, was selected and loaded with polyaniline(PANI) on its surface to successfully construct a superhydrophobic fiber material. It was then woven with hydrophilic cotton(Cot) fibers to form a superhydrophobic/hydrophilic heterogeneous material(PANI/PTFE-Cot) for the treatment of oily wastewater. The results indicated that PANI with micro-nano structure was successfully loaded on PTFE fibre, and the dosage of aniline and reaction temperature affected the hydrophobicity of PANI/PTFE. When the reaction temperature was 25 ℃ and the dosage of aniline was 0.2 mol/L,the water contact angle reached its maximum of 154°. Compared with that of PTFE,the quality factor of 2∶1 PANI/PTFE-Cot increased 46.7%.

Background and Aims Introgressive hybridization poses a challenge to taxonomic and phylogenetic understanding of taxa, particularly when there are high numbers of co-occurring, intercrossable species. The genus Quercus exemplifies this situation. Oaks are highly diverse in sympatry and cross freely, creating syngameons of interfertile species. Although a well-resolved, dated phylogeny is available for the American oak clade, evolutionary relationships within many of the more recently derived clades remain to be defined, particularly for the young and exceptionally diverse Mexican white oak clade. Here, we adopted an approach bridging micro- and macroevolutionary scales to resolve evolutionary relationships in a rapidly diversifying clade endemic to Mexico. Methods Ecological data and sequences of 155 low-copy nuclear genes were used to identify distinct lineages within the Quercus laeta complex. Concatenated and coalescent approaches were used to assess the phylogenetic placement of these lineages relative to the Mexican white oak clade. Phylogenetic network methods were applied to evaluate the timing and genomic significance of recent or historical introgression among lineages. Key Results The Q. laeta complex comprises six well-supported lineages, each restricted geographically and with mostly divergent climatic niches. Species trees corroborated that the different lineages are more closely related to other species of Mexican white oaks than to each other, suggesting that this complex is polyphyletic. Phylogenetic networks estimated events of ancient introgression that involved the ancestors of three present-day Q. laeta lineages. Conclusions The Q. laeta complex is a morphologically and ecologically related group of species rather than a clade. Currently, oak phylogenetics is at a turning point, at which it is necessary to integrate phylogenetics and ecology in broad regional samples to figure out species boundaries. Our study illuminates one of the more complicated of the Mexican white oak groups and lays groundwork for further taxonomic study. [ABSTRACT FROM AUTHOR]

The results of studies of hot cracks formed in cast shapes from low-alloy steel G21Mn5 are presented. Macroand microstructural analyses are carried out. Fractography studies of samples cut from castings used in the production of railway freight cars are performed. The criteria used to assess the susceptibility of alloys to hot brittleness are considered. It is shown that the orientation of dendritic crystals affects significantly the formation of hot cracks, and the direction of the dendrite growth is determined by the conditions of heat dissipation, which are influenced in their turn by the geometry of the casting. The phenomenon of coalescence under the conditions of misorientation of neighbor dendrites and its effect on the formation of hot cracks is studied. A modified RDG criterion is suggested, which allows for the influence of the geometry of the cast product on the formation of hot cracks through the angle of misorientation of neighbor crystals. [ABSTRACT FROM AUTHOR]

Copyright of Industrial Water Treatment is the property of CNOOC Tianjin Chemical Research & Design Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Petroleum Geology & Recovery Efficiency is the property of Petroleum Geology & Recovery Efficiency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The dynamics of two gas bubbles rising in a stagnant viscous liquid is studied. The mathematical model is based on the laws of conservation of mass, momentum and energy, taking into account the compressibility of media. The gas is assumed to be calorically perfect. To trace the gas–liquid interface, the volume of fluid method is used. The solution to the problem is carried out using the finite volume method. The evolution of the bubble shape during the process of ascent and hydrodynamic interaction is shown. The change in the bubble shapes occurs under the influence of buoyancy force, drag force, viscous force, inertia force, and surface tension force. The results of the test calculations are in good agreement with the known data of other authors. The mechanism of coalescence of bubbles is described in the case of their movement one after another, when one bubble falls into the region of the hydrodynamic wake of another. Dependencies of bubble volume and temperature change on time are established. [ABSTRACT FROM AUTHOR]

The physical stability of a whey protein (WP)-stabilized red palm oil (RPO) emulsion as affected by the type and concentration of WP used was evaluated by monitoring the changes in its droplet characteristics after storage and accelerated testing. Emulsions containing 30% (v/v) RPO were stabilized by WP isolate 90 (WPI), WP concentrate 80 (WPC80), or WP concentrate 76 (WPC76) at various concentrations (2.5–15% (w/v)) via emulsification employing a two-step rotor-stator homogenization combined with a phase inversion technique. Based on the results, changes in droplet characteristics did not always represent the visually observed stability of the emulsions. In this study, WPCs performed better than WPI in forming a stable RPO emulsion. Higher WP concentrations produced smaller emulsion droplet sizes with better emulsion stability when stored at varied temperatures (i.e., 30 °C, 45 °C, and 60 °C). However, when stored at 60 °C, all the emulsions produced were least stable. Based on the results, the 15% WPC76-stabilized emulsion showed the best stability. This study found that the droplet size characterization could not fully explain the stability of the emulsion, and the emulsion investigated destabilized through different dominant mechanisms when it was stored compared to when it was centrifuged. This study provides information needed for developing a stable WP-stabilized emulsion to be the RPO carrier system. [ABSTRACT FROM AUTHOR]

Microinclusions in steel will significantly affect mechanical performance of final products and therefore require serious concern during metallurgical process. Herein, the collision, coalescence as well as floatation of bubble–inclusion coexisting system is fully studied through a new mathematical model. It comes to the following conclusions: as bubbles rise, they induce a flow of liquid steel from their upper surface to their lower surface, and inclusion droplets rise and collide in the wake of the bubble. The velocity of the bubbles is affected by their deformation, with deformation rates being linked to the Weber number. The coalescence time of these inclusions is primarily influenced by viscosity and surface tension. Coalescence accelerates with higher surface tension or reduced viscosity, and this phenomenon can be described by a formula, which is developed by simulation results. According to this formula, coalescence time of 3CaO·Al2O3 is 20% longer than that of 12CaO7·Al2O3. Consequently, 12CaO7·Al2O3 is more prone to coalescence. The movement of inclusions can be controlled by adjusting gas volume and flow rate. Moreover, promoting coalescence can be achieved by altering the viscosity of inclusions and the surface tension coefficient, making it easier to remove these unwanted inclusions. [ABSTRACT FROM AUTHOR]

Rapid species radiations present difficulties for phylogenetic reconstruction due to lack of phylogenetic information and processes such as deep coalescence/incomplete lineage sorting and hybridization. Phylogenomic data can overcome some of these difficulties. In this study, we use anchored hybrid enrichment (AHE) nuclear phylogenomic data and mitochondrial genomes recovered from AHE bycatch with several concatenated and coalescent approaches to reconstruct the poorly resolved radiation of the New Zealand cicada species in the genera Kikihia Dugdale and Maoricicada Dugdale. Compared with previous studies using only three to five Sanger‐sequenced genes, we find increased resolution across our phylogenies, but several branches remain unresolved due to topological conflict among genes. Some nodes that are strongly supported by traditional support measures like bootstraps and posterior probabilities still show significant gene and site concordance conflict. In addition, we find strong mito‐nuclear discordance; likely the result of interspecific hybridization events in the evolutionary history of Kikihia and Maoricicada. [ABSTRACT FROM AUTHOR]

The potential of a finite-element technique based on an egalitarian meshing of the space–time domain D of physical problems described by parabolic or hyperbolic differential equations is explored. A least-squares minimization technique is applied in the meshed domain D to obtain stiffness-like matrices associated with various linear differential operators. Applications discussed include problems of boundary growth, and diffusive coalescence, in which D cannot be regarded as the Cartesian product of two independent domains in space and time. [ABSTRACT FROM AUTHOR]

Ni–Al films produced by resistive thermal evaporation using a VUP-5 vacuum station are studied. The basic stages in film synthesis are described. The wavefront velocity in synthesis is determined, along with the radial growth rate of the nuclei (islands) formed. The grain size in the surface is investigated. Fourier analysis provides information regarding the structural properties of the surface. The electrical conductivity of the thin metallic film is determined. [ABSTRACT FROM AUTHOR]

Antibiotic resistance is an escalating global health concern, exacerbated by the pervasive presence of antibiotic resistance genes (ARGs) in natural environments. The Yangtze River, the world's third-longest river, traversing areas with intense human activities, presents a unique ecosystem for studying the impact of these genes on human health. Here, we explored ARGs in the Yangtze River, examining 204 samples from six distinct habitats of approximately 6000 km of the river, including free-living and particle-associated settings, surface and bottom sediments, and surface and bottom bank soils. Employing shotgun sequencing, we generated an average of 13.69 Gb reads per sample. Our findings revealed a significantly higher abundance and diversity of ARGs in water-borne bacteria compared to other habitats. A notable pattern of resistome coalescence was observed within similar habitat types. In addition, we developed a framework for ranking the risk of ARG and a corresponding method for calculating the risk index. Applying them, we identified water-borne bacteria as the highest contributors to health risks, and noted an increase in ARG risks in particle-associated bacteria correlating with heightened anthropogenic activities. Further analysis using a weighted ARG risk index pinpointed the Chengdu–Chongqing and Yangtze River Delta urban agglomerations as regions of elevated health risk. These insights provide a critical new perspective on ARG health risk assessment, highlighting the urgent need for strategies to mitigate the impact of ARGs on human health and to preserve the ecological and economic sustainability of the Yangtze River for future human use.

We report the first measurements of cumulants, up to 4th order, of deuteron number distributions and proton-deuteron correlations in Au+Au collisions recorded by the STAR experiment in phase-I of Beam Energy Scan (BES) program at the Relativistic Heavy Ion Collider. Deuteron cumulants, their ratios, and proton-deuteron mixed cumulants are presented for different collision centralities covering a range of center-of-mass energy per nucleon pair sNN=7.7 to 200 GeV. It is found that the cumulant ratios at lower collision energies favor a canonical ensemble over a grand canonical ensemble in thermal models. An anti-correlation between proton and deuteron multiplicity is observed across all collision energies and centralities, consistent with the expectation from global baryon number conservation. The UrQMD model coupled with a phase-space coalescence mechanism qualitatively reproduces the collision-energy dependence of cumulant ratios and proton-deuteron correlations.

Abstract Background Microbial communities are of tremendous importance for ecosystem functioning and yet we know little about the ecological processes driving the assembly of these communities in the environment. Here, we used an unprecedented experimental approach based on the manipulation of physical distance between neighboring cells during soil colonization to determine the role of bacterial interactions in soil community assembly. We hypothesized that experimentally manipulating the physical distance between bacterial cells will modify the interaction strengths leading to differences in microbial community composition, with increasing distance between neighbors favoring poor competitors. Results We found significant differences in both bacterial community diversity, composition and co-occurrence networks after soil colonization that were related to physical distancing. We show that reducing distances between cells resulted in a loss of bacterial diversity, with at least 41% of the dominant OTUs being significantly affected by physical distancing. Our results suggest that physical distancing may differentially modulate competitiveness between neighboring species depending on the taxa present in the community. The mixing of communities that assembled at high and low cell densities did not reveal any “home field advantage” during coalescence. This confirms that the observed differences in competitiveness were due to biotic rather than abiotic filtering. Conclusions Our study demonstrates that the competitiveness of bacteria strongly depends on cell density and community membership, therefore highlighting the fundamental role of microbial interactions in the assembly of soil communities.

Background: Microbial communities are of tremendous importance for ecosystem functioning and yet we know little about the ecological processes driving the assembly of these communities in the environment. Here, we used an unprecedented experimental approach based on the manipulation of physical distance between neighboring cells during soil colonization to determine the role of bacterial interactions in soil community assembly. We hypothesized that experimentally manipulating the physical distance between bacterial cells will modify the interaction strengths leading to differences in microbial community composition, with increasing distance between neighbors favoring poor competitors. Results: We found significant differences in both bacterial community diversity, composition and co-occurrence networks after soil colonization that were related to physical distancing. We show that reducing distances between cells resulted in a loss of bacterial diversity, with at least 41% of the dominant OTUs being significantly affected by physical distancing. Our results suggest that physical distancing may differentially modulate competitiveness between neighboring species depending on the taxa present in the community. The mixing of communities that assembled at high and low cell densities did not reveal any "home field advantage" during coalescence. This confirms that the observed differences in competitiveness were due to biotic rather than abiotic filtering. Conclusions: Our study demonstrates that the competitiveness of bacteria strongly depends on cell density and community membership, therefore highlighting the fundamental role of microbial interactions in the assembly of soil communities. [ABSTRACT FROM AUTHOR]

Surfaces with micro/nano‐structures significantly enhance the critical heat flux of nucleate boiling by increasing the wickability of the liquid phase to delay film boiling. An alternative strategy, of removing surface bubbles at smaller sizes, is largely ignored. Here, they fabricate a rationally designed micro‐structured surface that enables the coalescence‐induced departure of microscopic vapor bubbles during the pool boiling of water at diameters an order of magnitude smaller than single‐bubble buoyant departure. Arrays of micro‐cavities or micro‐grooves serve as tailored nucleation sites to nucleate close‐packed vapor bubbles, which coalesce at unusually small sizes compared to a homogeneous surface. Two different modes of coalescence‐induced bubble departure are observed and modeled: capillary‐inertial jumping for smaller micro‐bubbles and buoyant‐inertial liftoff for larger micro‐bubbles. Capillarity‐enhanced pool boiling on micro‐structured surfaces has the potential to dramatically enhance the heat transfer coefficient and critical heat flux of pool boiling. [ABSTRACT FROM AUTHOR]

Chromosomal inversions may play a central role in speciation given their ability to locally reduce recombination and therefore genetic exchange between diverging populations. We analyzed long- and short-read whole-genome data from sympatric and allopatric populations of 2 Drosophila virilis group species, Drosophila montana and Drosophila flavomontana , to understand if inversions have contributed to their divergence. We identified 3 large alternatively fixed inversions on the X chromosome and one on each of the autosomes 4 and 5. A comparison of demographic models estimated for inverted and noninverted (colinear) chromosomal regions suggests that these inversions arose before the time of the species split. We detected a low rate of interspecific gene flow (introgression) from D. montana to D. flavomontana , which was further reduced inside inversions and was lower in allopatric than in sympatric populations. Together, these results suggest that the inversions were already present in the common ancestral population and that gene exchange between the sister taxa was reduced within inversions both before and after the onset of species divergence. Such ancestrally polymorphic inversions may foster speciation by allowing the accumulation of genetic divergence in loci involved in adaptation and reproductive isolation inside inversions early in the speciation process, while gene exchange at colinear regions continues until the evolving reproductive barriers complete speciation. The overlapping X inversions are particularly good candidates for driving the speciation process of D. montana and D. flavomontana , since they harbor strong genetic incompatibilities that were detected in a recent study of experimental introgression. [ABSTRACT FROM AUTHOR]

This work presents the factors that determine the coalescence of the micron-sized oil droplets (<0.4 μm) and the permeation flux by using two different types of commercial flat-sheet microporous polyvinylidene fluoride (PVDF) membranes. Results show that the PVDF-Westran membrane coalesced the oil droplets up to 1.1 μm while the PVDF-Synder membrane enlarged the oil droplets to approximately 5.6 μm. The pore size distribution instead of the both casted and fibrous membrane structures influenced the coalescence of the oil droplets. The membrane feed side that comprised of the smaller pores exhibited better in the coalescence while the pore size on the membrane permeate side did not show the significant effect on the coalescence. The water permeation flux was proportional to the pore size of the membrane feed side while the permeation flux during the coalescence was inversely proportional to the membrane pore size. The oil droplets in the feed solution has reduced the permeation flux about 10 times lower. The addition of the polyacrylamide in the oily water has essentially fouled the membranes at least 1.4 times higher and the foulant has induced the cleavage effect on the oil droplets. [ABSTRACT FROM AUTHOR]

Research efforts have been dedicated to predicting microstructural evolution during solidification processes. The main secondary arm spacing controls the mushy zone's permeability. The aim of the current work was to build a simple sub-grid model that describes the growth and coarsening of secondary side dendrite arms. The idea was to reduce the complexity of the curvature distribution with only two adjacent side arms in concurrence. The model was built and applied to the directional solidification of Al-06wt%Cu alloy in a Bridgman experiment. The model showed its effectiveness in predicting coarsening phenomena during the solidification of Al-06wt%Cu alloy. The results showed a rapid growth of both arms at an earlier stage of solidification, followed by the remelting of the smaller arm. In addition, the results are in good agreement with an available time-dependent expression which covers the growth and coarsening. Such model can be implemented as a sub-grid model in volume average models for the prediction of the evolution of the main secondary arms spacing during macroscopic solidification processes. [ABSTRACT FROM AUTHOR]

High shear mixing of powders in the presence of liquid addition can lead to the enlargement of primary powder particles, forming larger structures referred to as granules. This particle growth can occur through distinct mechanisms, including layering, coalescence, or a combination of both, and the prevailing mechanism is influenced by a multitude of process and formulation variables. In this study, we quantified the influence of process variables such as vessel inclination, rotational direction of the vessel, impeller speed, mixing duration, and rotation speed of the vessel pan on the particle growth mechanism. We accomplished this through rigorous image analysis of granule samples produced under varying conditions. Furthermore, our investigation extended to encompass the effects of formulation variables, including the particle density of the primary powder, the quantity of binder added, and the particle size of the coating material. Our findings revealed that the coating mechanism predominantly governed particle growth when the mixing time was brief, the mixer vessel had a high inclination angle, and the vessel rotated in a direction opposite to that of the agitator. The coating material utilization factor, denoting the ratio of the mass fraction of coating material added that effectively participates in the formation of coated seeds (each with a single seed) to the fraction of coating material engaged in competing mechanisms, serves as a crucial indicator of the prevailing mechanism within specific process and formulation conditions. [Display omitted] • Coating mechanism dominate when mixing time is short. • High inclination angle of vessel promotes coating. • At higher impeller speed longer mixing time diminishes coating efficiency and quality. • There is an inverse correlation between the number of coalesced seed particle and coating efficiency. [ABSTRACT FROM AUTHOR]

Abstract—The behavior of a "water-in-oil" emulsion stabilized with asphaltenes under the action of an inhomogeneous alternating electric field has been studied. The experimental technique was based on the use of microfluidics, optical microscopy, and high-speed video filming. The dependences of quantitative estimates of the parameters characterizing the dynamics of the emulsion destruction on the frequency and amplitude of the applied field have been obtained. The technique will be useful in developing efficient methods for breaking emulsions and modifying the existing technologies for separating oil emulsions into phases. [ABSTRACT FROM AUTHOR]

We study experimentally the flow of non-wetting ganglia during the co-injection of n-heptane and water in a predominantly 2D PMMA micromodel, which is constructed based on a stochastic digital algorithm. The dynamics of the phase distribution patterns are recorded optically and post-processed using cluster identification and motion tracking algorithms in order to study the characteristics and the interactions between the mobile and stranded ganglia populations. We focus primarily on the effects of the capillary number (Ca) and the ratio of the injection flow rates (Q) on the observed ganglia size distributions and the effective two-phase rheology. Our experimental setup allows for the study of ganglia fragmentation and coalescence dynamics over five orders of magnitude (in terms ganglia sizes), thus offering novel physical insight on the pore-scale characteristics of different ganglia populations and on how their interactions determine the relative permeability of the non-wetting phase. We demonstrate that the rates of ganglia fragmentation and coalescence intensify at higher Ca values, as viscous forces become dominant over capillary ones, leading to a log-normal size distribution that shifts toward smaller mean values. This effect is directly correlated with the emergence of new flow paths that develop progressively through narrower pores-throats, where the continuous wetting phase sweeps ganglia with sizes smaller than the mean pore-throat diameter. These flow paths further contribute to the Darcy scale velocity of the non-wetting phase, thus leading to a power-law Darcian regime at intermediate Ca values with a scaling exponent that is found to be a function of Q. [ABSTRACT FROM AUTHOR]

BACKGROUND: Pickering emulsions are a kind of emulsion stabilized by solid particles. These particles generate a physical or mechanical barrier that provides long‐term stability to emulsion. Cellulose nanofibers are effective Pickering emulsifiers given their long length, high flexibility and entanglement capability. In this work, soybean hull insoluble polysaccharides (HIPS) were used as source of cellulose nanofibers by using a combination of chemical and mechanical treatment. The chemical composition, morphology, flow behavior, water holding capacity (WHC) and emulsifying properties of the nanofibers were studied. RESULTS: Nanofibers with diameters between 35 and 110 nm were obtained. The WHC increased significantly after the mechanical treatment, and the rheological behavior of the nanofibers was typical of cellulosic materials. Nanofibers were effective emulsifiers in oil‐in‐water (O/W) emulsions formulated under acidic conditions, without the need of using any additional surfactant. Emulsions were not affected by changes in the pH of the medium (3.00–5.00), and were stable to coalescence. CONCLUSION: It is possible that cellulose nanofibers form an entangled network which acts as a mechanical steric barrier, providing stability to coalescence. These results are important for the development of effective O/W Pickering emulsifiers/stabilizers, with large applications in the food industry. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations were conducted to investigate the coalescence mechanism of carbon nanoparticles. The analytical objects were two clusters composed of benzene, anthracene, phenanthrene or coronene molecules, and those clusters were placed next to each other. These numerical analyses used isoPAHAP potential to describe the intermolecular interaction and OPLS–AA potential to account for intramolecular interaction. Since the behavior below and above the melting point is entirely different, the melting point of the cluster was first determined. The coalescence behavior was investigated at temperatures 30 K below the melting point, 5 K below the melting point, and 50 K above the melting point. The coalescence of benzene clusters progressed through three stages: fast shrinking at 0–0.4 ns; gradual and constant shrinking at 0.4–4 ns; and little shrinking after 4 ns. This indicates that the coalescence of benzene clusters is analogous to that of inorganic nanoparticles. However, the number of coalescence stages of coronene clusters was more than four. The coronene cluster looked composed of 4–6 molecules of crystallites. Due to the strong interaction among molecules within crystallites, the diffusion of molecules in crystallites would hardly occur. Thus, the coalescence of coronene clusters would proceed with the breaking of crystallites. [Display omitted] • Carbon nanoparticles were assumed as PAH clusters. • Coalescence of carbon nanoparticle was investigated by MD simulation. • Coalescence was multi-staged, different mechanism from metal nanoparticles. [ABSTRACT FROM AUTHOR]

We investigate quasi-two-dimensional coalescence of domains of isotropic liquid in chiral liquid crystal in flat optical cells. It is demonstrated that coalescence can be accompanied by instability of the liquid crystal bridge separating the domains. We analyse the transformation of the bridge for materials in a wide range of the pitch of the cholesteric helix and different spatially modulated structures: planar cholesteric, one-dimensional stripe structure, focal conic structure and Blue Phases. The instability is followed by cascade break-up and formation of satellite cholesteric droplets. This picture differs from the standard three-dimensional coalescence scenario, where only a bridge between the droplets forms and grows. Studies of thinning dynamics in the bridge region showed that at the final stage of instability the width of the cholesteric bridge decreased linearly with time. In cholesteric with high chirality and small helical pitch the bridge thinning occurs substantially slower than in cholesteric with large helical pitch. [ABSTRACT FROM AUTHOR]

CdS‐based materials are extensively studied for photocatalytic water splitting. By incorporating Ag+ into CdS nanomaterials, the catalyst's charge carrier dynamic can be tuned for photo‐electrochemical devices. However, photo‐corrosion and air‐stability of the heterostructures limit the photocatalytic device's performance. Here, a one‐pot, single molecular source synthesis of the air‐stable AgCdS ternary semiconductor alloy nanostructures by heat‐up method is reported. Monoclinic and hexagonal phases of the alloy are tuned by judicious choice of dodecane thiol (DDT), octadecyl amine (ODA), and oleyl amine (OLA) as capping agents. Transmission electron microscope (TEM) and powder X‐ray diffraction characterization of the AgCdS alloy confirm the monoclinic and hexagonal phase (wurtzite) formation. The high‐resolution TEM studies confirm the formation of AgCdS@DDT alloy nanorods and their shape transformation into nano‐triangles. The nanoparticle coalescence is observed for ODA‐capped alloys in the wurtzite phase. Moreover, OLA directs mixed crystal phases and anisotropic growth of alloy. Optical processes in AgCdS@DDT nano‐triangles show mono‐exponential decay (3.97 ± 0.01 ns). The monoclinic phase of the AgCdS@DDT nanorods exhibits higher electrochemical hydrogen evolution activity in neutral media as compared to the AgCdS@ODA/OLA alloy nanocrystals. DDT and OLA‐capped alloys display current densities of 14.1 and 14.7 mA cm−2, respectively, at 0.8 V (vs RHE). [ABSTRACT FROM AUTHOR]

Binary droplet collision is a basic fluid phenomenon for many spray processes in nature and industry involving lots of discrete droplets. It exists an inherent mirror symmetry between two colliding droplets. For specific cases of the collision between two identical droplets, the head-on collision and the off-center collision, respectively, show the axisymmetric and rotational symmetry characteristics, which is useful for the simplification of droplet collision modeling. However, for more general cases of the collision between two droplets involving the disparities of size ratio, surface tension, viscosity, and self-spin motions, the axisymmetric and rotational symmetry droplet deformation and inner flow tend to be broken, leading to many distinct phenomena that cannot occur for the collision between two identical droplets owing to the mirror symmetry. This review focused on interpreting the asymmetric droplet deformation and the collision-induced internal mixing that was affected by those symmetry breaking factors, such as size ratio effects, Marangoni Effects, non-Newtonian effects, and droplet self-spin motion. It helps to understand the droplet internal mixing for hypergolic propellants in the rocket engineering and microscale droplet reactors in the biological engineering, and the modeling of droplet collision in real combustion spray processes. [ABSTRACT FROM AUTHOR]

The willistoni group of Drosophila is subdivided into the alagitans, bocainensis, and willistoni subgroups, and has been an important model for studying evolutionary processes in the Neotropics for decades. Phylogenetic studies place the bocainensis subgroup as a grade in relation to the monophyletic willistoni subgroup, although these included molecular or morphological data for up to 4 species of the 12 species included in the first subgroup. Here, we characterized the first nucleotide sequences for three mitochondrial and five nuclear genes of Drosophila bocainensis Pavan & da Cunha, 1947 and employed these for addressing the paraphyly of this subgroup under a coalescent approach. Our results still recovered this paraphyletic relationship, placing D. bocainensis, Drosophila capricorni Dobzhansky & Pavan, 1943 and Drosophila sucinea Patterson & Mainland, 1944 in a basal clade, which diverged around 6.81 million years ago. The relationship of Drosophila nebulosa Sturtevant, 1916 and Drosophila fumipennis Duda, 1925 as a sister clade to the willistoni subgroup was recovered. The possible causes of such paraphyly are discussed. [ABSTRACT FROM AUTHOR]

In the last ten years, advances in experimental techniques have enabled remarkable discoveries of how the dynamics of thin gas films can profoundly influence the behavior of liquid droplets. Drops impacting onto solids can skate on a film of air so that they bounce off solids. For drop–drop collisions, this effect, which prevents coalescence, has been long recognized. Notably, the precise physical mechanisms governing these phenomena have been a topic of intense debate, leading to a synergistic interplay of experimental, theoretical, and computational approaches. This review attempts to synthesize our knowledge of when and how drops bounce, with a focus on (a) the unconventional microscale and nanoscale physics required to predict transitions to/from merging and (b) the development of computational models. This naturally leads to the exploration of an array of other topics, such as the Leidenfrost effect and dynamic wetting, in which gas films also play a prominent role. [ABSTRACT FROM AUTHOR]

Amalgamation of metal nanoparticles (NPs) with mercury (Hg) and the accompanying changes in morphology or localized surface plasmon resonance have received increasing attention in recent years because of their potential applicability in mercury sensing for environmental protection. In this work, the amalgamation of silver NPs (Ag NPs) densely assembled on a silica nanoparticle core is achieved simply by an incubation with aqueous Hg2+. The formation of the Ag–Hg amalgam is followed not only by a coalescence between Ag NPs on silica NP cores but also by a prompt suppression of their surface-enhanced Raman scattering (SERS) activity. Based on the observations, we hypothesize that the suppression of the SERS signal is attributed to the deformation of nanojunctions where the electromagnetic hotspots are located during the coalescence process. In addition, we propose a reducing agent-free method for Hg2+ detection by utilizing the correlation between Hg2+ concentration and the following SERS signal of 4-fluorobenzenethiol introduced as a Raman dye. In the evaluation of analytical performance, the proposed method exhibits rapidness within 1 min and improved signal reproducibility with relative standard deviations below 4.62% compared to the conventional SERS methods for Hg2+ detection. [ABSTRACT FROM AUTHOR]

In order to elucidate the oil displacement mechanism of micro-emulsions formed by different betaines at pore throats, this study selected three betaine surfactants with different hydrophobic branched chains for a microscopic visualization oil displacement experiment. The interfacial tension, dilational modulus, interactions of oil droplets, and apparent viscosity of the emulsions were measured. Besides, the microscopic oil displacement mechanism and oil displacement effects of different betaines in homogeneous and heterogeneous models were investigated. The results revealed the beneficial interfacial activity and viscosity enhancement effects of the three betaine solutions. With the increase in the branched degree of betaines, the strength of interfacial films and the viscosity enhancement effect decreases. In the homogeneous model, betaine solutions emulsify crude oil into droplets with strong interfacial films. The in-situ plugging effect improves oil recovery and the sweep efficiency in the pore throats, and the remaining oil is mainly in the form of droplets. As the branched degree increases, the strength of the interfacial films and the oil recovery decline. In the heterogeneous model, the plugging effect enhances the pore structure heterogeneity. The three betaine solutions can increase the sweep efficiency but the displacement solutions only migrate along the dominant pathway within the sweep range. As a result, a large amount of isolated cluster residual oil remains, resulting in similar oil recovery efficiency for betaine flooding to that of water flooding in the heterogeneous model. [ABSTRACT FROM AUTHOR]

Riverine microorganisms are major players in driving biogeochemical cycling. The dynamics of hydrological conditions have been observed to influence the microbial communities in rivers, but their specific impacts on the coalescence patterns of the bacterial communities remain largely unexplored. In this study, we examined the dynamics of the sedimentary bacterial communities and their coalescence patterns with bacterioplankton communities in a plain river network under dynamic hydrological conditions. Our results revealed significant temporal variations in the diversity, structure, and taxonomic composition of the sedimentary bacterial communities across the wet, normal, and dry seasons (P < 0.01). Despite the varying hydrological conditions, similar coalescence patterns were observed between the sedimentary bacterial communities and bacterioplankton communities. The bacterial communities from the same habitat type showed higher proportions of overlapped species, and the coalescence was more prominent within the same medium (intra-medium) compared to that between different media (inter-medium). However, the proportions of stochasticity in community assembly were distinct during different hydrological conditions, with evidently increased stochasticity observed in the wet season compared with other seasons. These results implied that the similar coalescence patterns between the sedimentary bacterial communities and bacterioplankton communities were driven by distinct assembly processes. The results of this study expanded our understanding of microbial coalescence in a river network and might shed light on how microbial communities are assembled in river ecosystems. IMPORTANCE Microorganisms play important roles in driving the biogeochemical cycles within river ecosystems. It has been suggested that hydrologic conditions could influence microbial communities in rivers, but their specific effects on the behaviours of microbial coalescence have not been thoroughly investigated. In this study, the dynamics of sedimentary bacterial communities within a plain river network were analyzed by amplicon sequencing followed by several ecological models to uncover the underlying assembly processes. Additionally, a comparative analysis between bacterioplankton communities and sedimentary bacterial communities was performed to unveil their coalescence patterns. The results suggested that similar coalescence patterns between sedimentary bacterial and bacterioplankton communities were driven by distinct assembly processes under dynamic hydrological conditions. These findings enhanced our understanding of microbial diversity features within river ecosystems. [ABSTRACT FROM AUTHOR]

The coalescence of two growing bubbles presents unique characteristics compared to static bubble coalescence. The gas injection flowrate significantly affects the different stages of bubble evolution, which is poorly understood. In this study, we investigate the flowrate effects on the lateral coalescence of two growing bubbles experimentally. The synchronous bubbling from adjacent needles is achieved using water to push air. During the bubble growth process, we find that the initial nonlinear evolution of bubble volume is because the bubble emerges as a small spherical cap with a large curvature radius and apparent contact angle. As the neck expands after bubble coalescence, the injection flowrate accelerates the neck evolution compared to the case without air injection. We find the neck expansion time decreases linearly with increasing flowrate, while the expansion speed increases with flowrate, but only in the early stage. Moreover, we propose a new theoretical expression that predicts the neck radius well at all the flowrates. At the post‐coalescence oscillation stage, the average projection area of the coalesced bubble increases linearly with time, except for periodic oscillations. Besides, we find that the injected air primarily influences the coalesced bubble's height, which in turn affects the projection area. [ABSTRACT FROM AUTHOR]

The process of building a model or copy of a real-world system and assessing its behaviour under various scenarios is referred to as simulation. Simulation in population genetics is the process of simulating a population's genetic makeup and evolutionary history using mathematical models and computer algorithms. It is important in population genetics for a better understanding of the impact of various evolutionary and demographic scenarios on sequence variation and patterns, it allows investigators to better assess and design analytical methods in the study of disease-associated genetic factors. This is an important tool for studying population genetic diversity and how natural selection, genetic drift, mutation, migration, and other evolutionary forces have influenced the genetic makeup of the population. There are three fundamental frameworks for simulation: coalescent, forward, and resampling methods. Numerous simulators that fit under these frameworks can be compared in terms of their evolutionary and demographic scenarios, computing complexity, and particular applications. Population simulation is becoming increasingly important in evolutionary biology, enabling researchers to explore the effects of various genetic models on genetic diversity and DNA sequence patterns. [ABSTRACT FROM AUTHOR]

Water in heavy crude oil (W/O) emulsions, which are stubborn mixtures of immiscible heavy crude oil and brine, are a ubiquitous challenge in the petroleum industry. They cause serious corrosion problems, increase the viscosity of petroleum and make the production cost very high. This phenomenon appears during the production of crude oil and should be treated to maximize the overall profitability of oil production and meet transportation requirement. Surfactants are some of the most useful demulsifiers and play a pivotal role in breaking brine/oil emulsions. Herein, we aimed to combine ethyleneamine units and ethyleneoxide units to prepare star-shaped surfactants and test the effect of this combination on the demulsification performance. First, diethylenetriamine reacted with glycidyl 4-nonyl ether (GNE) through an epoxy ring opening to prepare trinonyl phenoxy diethylenetriamine (TNDT). Then, ethylene oxide units were introduced via the interaction of hydroxyl groups with 2-(2-chloroethoxy)ethanol to form ethoxylated trinonyl phenoxy diethylenetriamine (ETNDT). The chemical structures of the surfactants were verified via FTIR and NMR characteristic techniques. The surfactants were applied as demulsifiers for W/O emulsions. It was found that the introduction of the ethyleneoxide units enhanced the solubility of the water and the demulsification performance of the prepared surfactants. The demulsification efficiency was enhanced via ethoxylation and reached 100% for ETNDT for most of the W/O emulsions. [ABSTRACT FROM AUTHOR]

Nanobubbles (NBs), with their unique physicochemical properties and promising applications, have become an important research topic. Generation of monodispersed bulk NBs with specified gas content remains a challenge. We developed a simple method for generating bulk NBs, using porous alumina films with ordered straight nano-scaled holes. Nanoparticle tracking analysis (NTA) is used to confirm NB formation. The NTA data demonstrates that NB size is distributed discretely with a uniform increment factor of √2. To explain the observed characteristic size distribution of NBs, we propose a simple model in which two NBs of the same size are assumed to preferentially coalesce. [ABSTRACT FROM AUTHOR]

This article considers the role of thunder in the production of rain by gravitational processes. A previous numerical work has shown that a thunder event also numerically, the coalescence effects produced by both thunderclaps and gravity in a cumulus congestus cloud that had more than four times the liquid content of that lean cloud. Those effects are studied separately and in tandem, using the same set of assumptions. Therefore, the results presented here provide a basis for the comparison of the effectiveness of each type to produce droplet growth in thunderclouds. For thunder alone, these results show that a small number of thunderclaps can in less than 2 s produce mean size growths larger than 50%. For gravity alone, it is found that after 60 s, the longest time considered, gravitational coalescence increases the mean diameter of the original droplet size distribution by 20%. The tandem study considers the effects produced by gravitation on the droplet size distribution that resulted after the original distribution was modified by four or five thunderclaps. Significant increases are found in both cases. For four claps it was found that the mean size increased by 71% in 60 s. The corresponding growth for five claps was slightly larger than 100%. These substantial increases also show that the growths produced by the thunderclaps are not simply additive, but significantly accelerate those produced by gravitation. This acceleration implies that the droplet size growths produced by thunderclaps can substantially decrease the time required by gravitational coagulation to produce raindrops in rainclouds. [ABSTRACT FROM AUTHOR]

Coalescence of nanowires and other three-dimensional structures into continuous film is desirable for growing low-dislocation-density III-nitride and III-V materials on lattice-mismatched substrates; this is also interesting from a fundamental viewpoint. Here, we develop a growth model for vertical nanowires which, under rather general assumptions on the solid-like coalescence process within the Kolmogorov crystallization theory, results in a morphological diagram for the asymptotic coverage of a substrate surface. The coverage is presented as a function of two variables: the material collection efficiency on the top nanowire facet a and the normalized surface diffusion flux of adatoms from the NW sidewalls b . The full coalescence of nanowires is possible only when a = 1 , regardless of b . At a > 1 , which often holds for vapor–liquid–solid growth with a catalyst droplet, nanowires can only partly merge but never coalesce into continuous film. In vapor phase epitaxy techniques, the NWs can partly merge but never fully coalesce, while in the directional molecular beam epitaxy the NWs can fully coalesce for small enough contact angles of their droplets corresponding to a = 1 . The growth kinetics of nanowires and evolution of the coverage in the pre-coalescence stage is also considered. These results can be used for predicting and controlling the degree of surface coverage by nanowires and three-dimensional islands by tuning the surface density, droplet size, adatoms diffusivity, and geometry of the initial structures in the vapor–liquid–solid, selective area, or self-induced growth by different epitaxy techniques. [ABSTRACT FROM AUTHOR]

Arctic soils are constantly subjected to microbial invasion from either airborne, marine, or animal sources, which may impact local microbial communities and ecosystem functioning. However, in winter, Arctic soils are isolated from outside sources other than snow, which is the sole source of microorganisms. Successful colonisation of soil by snow microorganisms depends on the ability to survive and compete of both, the invading and resident community. Using shallow shotgun metagenome sequencing and amplicon sequencing, this study monitored snow and soil microbial communities throughout snow melt to investigate the colonisation process of Arctic soils. Microbial colonisation likely occurred as all the characteristics of successful colonisation were observed. The colonising microorganisms originating from the snow were already adapted to the local environmental conditions and were subsequently subjected to many similar conditions in the Arctic soil. Furthermore, competition-related genes (e.g. motility and virulence) increased in snow samples as the snow melted. Overall, one hundred potentially successful colonisers were identified in the soil and, thus, demonstrated the deposition and growth of snow microorganisms in soils during melt. [ABSTRACT FROM AUTHOR]

The coalescence behavior of soot and carbon black has not been so much discussed. The coalescence rate was obtained from the previous experimental results which measured the decrease in mobility diameter by re-heating with tandem differential mobility analyzer. Employing the rate expression used for sintering metallic and inorganic nanoparticles, it was found that the ease of coalescence varied with particle size. It was also suggested that the mechanism of coalescence may differ depending on the temperature. A model of coalescence kinetics based on crystallinity could not represent experimental coalescence kinetics. [Display omitted] • Estimation of coalescence rate constants for carbon nanoparticles. • Conventional formula greatly overestimates coalescing rate. • Coalescence was multi-staged, different mechanism from metal nanoparticles. [ABSTRACT FROM AUTHOR]

Many species that are birthed in one location and become reproductive in another location can be treated as if in a one-dimensional habitat where dispersal is biased downstream. One example of such is planktonic larvae that disperse in coastal oceans, rivers, and streams. In these habitats, the dynamics of the dispersal are dominated by the movement of offspring in one direction and the distance between parents and offspring in the other direction does not matter. We study an idealized species with non-overlapping generations in a finite linear habitat that has no larval input from outside of the habitat and is therefore isolated from other populations. The most non-realistic assumption that we make is that there are non-overlapping generations, and this is an assumption to be considered in future work. We find that a biased dispersal in the habitat reduces the average time to the most recent common ancestor and causes the average location of the most recent common ancestor to move from the center of the habitat to the upstream edge of the habitat. Due to the decrease in the time to the most recent common ancestor and the shift of the average location to the upstream edge, the effective population size (N e) no longer depends on the census size and is dependent on the dispersal statistics. We determine the average time and location of the most recent common ancestor as a function of the larval dispersal statistics. The location of the most recent common ancestor becomes independent of the length of the habitat and is only dependent on the location of the upstream edge and the larval dispersal statistics. [ABSTRACT FROM AUTHOR]

We consider a classical (capillary) model for a one-phase liquid in equilibrium. The liquid (e.g., water) is subject to a volume constraint, it does not mix with the surrounding vapour (e.g., air), it may come into contact with solid supports (e.g., a container), and it is subject to the action of an analytic potential field (e.g., gravity). The region occupied by the liquid is described as a set of locally finite perimeter (Caccioppoli set) in R³; no a priori regularity assumption is made on its boundary. The (twofold) scope in this note is to propose a weakest possible set of mathematical assumptions that sensibly describe a condition of stable equilibrium for the liquid-vapour interface (the capillary surface), and to infer from those that this interface is a smoothly embedded analytic surface. (The liquid-solid-vapour junction, or free boundary, can be present but is not analysed here.) The result relies fundamentally on the recent varifold regularity theory developed by the author and Wickramasekera, and on the identification of a suitable formulation of the stability condition. [ABSTRACT FROM AUTHOR]