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Simulation of the solid–liquid–gas interaction during solidification is challenging due to the presence of complex phase interfaces, bubble deformation, and high liquid/gas density ratio. In this work, a hybrid phase-field lattice-Boltzmann (PFLB) approach, together with a parallel and adaptive-mesh-refinement (Para-AMR) algorithm, is developed to model interactions between the gas bubble and solid growth front during solidification. The solid growth and bubble evolution are solved by the phase-field method. Both melt flow and bubble movement are determined by a kinetic-based lattice-Boltzmann model. Bubble dynamics during alloy solidification is modeled and compared with experiments, and a good agreement is achieved for various solid/liquid interfaces including planar, cellular, and dendritic interfaces. Results show that the effect of the bubble on solid array is dependent on the solid/liquid interface morphology, bubble size, and relative position between the bubble center and dendritic tip. Two interaction mechanisms, including engulfment and entrapment, are compared, and the difference is caused mainly by the redistribution of solute. The interaction mechanism between the rising multibubbles with large deformation and the dendritic array is also discussed.

Mechanically soft colloids (microgels) adsorbed at the interface between two fluids offer superior advantages over hard counterparts for a variety of applications ranging from foams/emulsion stabilization to the assembly of two-dimensional (2D) materials. Particle deformability and compressibility impart additional responses to microgel-laden interfaces that can be controlled on-demand by varying single-particle properties (e.g. crosslinking content and polymer density profile) and/or external parameters (e.g. interfacial compression and tension, temperature, oil polarity). In order to understand how single-particle softness influences the resulting material properties, a detailed quantification of the microgel's 3D conformation when confined at the fluid interface is of utmost importance. This article describes how different methodologies can be used to visualize, and in some case quantify, the conformation of adsorbed microgels, putting particular emphasis on the multiple advantages offered by in situ atomic force microscopy imaging at the fluid interface. The influence of the internal particle architecture, as well as that of temperature, interfacial tension and solubility in the organic phase, will be discussed. Finally, some perspectives on how softness can be exploited to tune the structural and mechanical properties of microgel monolayers will be provided., Chimia, 76 (10), ISSN:0009-4293

Cells are the basic building blocks of life. As such, they perform a plethora of functions, often realized through organelles, functional sub-units in the cell. Organelles have classically been though of as membrane-enclosed compartments. Recent advances, however, have shown that there are many organelles that lack a defining lipid membrane. Many such membraneless organelles, typically composed of protein and RNA, are liquid-like domains that form through phase separation inside the active, viscoelastic environment of living cells. While the ability of membraneless organelles to concentrate and segregate proteins within their bulk has been widely recognized, the importance of their surface is just starting to be appreciated. The surface energy of liquid interfaces leads to capillary phenomena, such as adhesion and wetting. The liquid-like nature of membraneless organelles thus suggests rich interactions between such droplets and other structures in the cell. In this thesis, we developed new statistical tools and physical theory to explore such phenomena and apply them to the interactions of stress granules, a membraneless organelle, with the components of the cytoskeleton. Microscopy is an important experimental tool to study living cells. However, due to the extremely complex and fluctuating environment in the cell, it is difficult to extract meaningful information on interactions between intracellular structures from individual images. Furthermore, images from different cells are often not comparable. We introduce a novel image analysis method that overcomes these challenges through creation of meaningful averages and reference states across many cells. Using these newly developed tools, we find that the microtubule network, which is an essential component of the cytoskeleton, is substantially denser in the vicinity of stress granules. When microtubules are depolymerized, their molecular building blocks adhere to the surface of stress granules. We capture this experimental observation in a thermodynamic model of partitioning of particles to the interface and bulk of two liquid phases. In this framework, our data are consistent with a weak (below kT) affinity of the microtubule sub-units for stress granule interfaces. As microtubules polymerize, their interfacial affinity increases, providing sufficient adhesion to deform droplets and/or the microtubule network. We validate this basic physical phenomenon in vitro through the interaction of a simple protein–RNA condensate with microtubules and their building blocks. Our work suggests that proteins and other objects in the cell have a non-specific affinity for droplet interfaces that increases with the contact area and becomes most apparent when they have no preference for the interior of a droplet over the rest of the cytoplasm. Another essential component of the cytoskeleton is actin, which forms dynamic networks that exhibit constant turnover and flow, which is important for cell motility. Similar analyses as for microtubules reveal repulsive interactions between stress granules and actin. Additionally, we find that stress granule motion is correlated with the flow of the actin network and that hydrodynamic coupling of stress granules and actin leads to directed transport towards microtubule-rich regions of the cell. Combined, our results present a comprehensive view of the interactions of stress granules with filamentous actin and microtubules. Stress granules are affected by wetting-mediated interactions with microtubules as well as hydrodynamic coupling to actin flow. Both of these physical mechanisms are non-specific, and therefore should be broadly applicable to other membraneless organelles and structures in the cell., Zellen sind die Grundbausteine des Lebens. Als solche erfüllen sie eine Fülle von Funktionen, die häufig durch Organellen, funktionelle Untereinheiten der Zelle, realisiert werden. Organellen wurden klassischerweise als von einer Membran umschlossene Kompartimente betrachtet. Jüngste Forschungsergebnisse haben jedoch gezeigt, dass es viele Organellen gibt, denen eine umschießende Lipidmembran fehlt. Viele dieser membranlosen Organellen sind flüssigkeitsähnliche Domänen, die sich innerhalb der aktiven, viskoelastischen Umgebung lebender Zellen durch Phasenseparation bilden. Während die Fähigkeit membranloser Organellen, Proteine zu konzentrieren und räumlich zu trennen, weithin anerkannt ist, beginnt man gerade erst die Bedeutung ihrer Oberfläche zu schätzen. Flüssige Oberflächen üben eine Spannung aus, die zu Kapillarphänomenen wie Adhäsion und Benetzung führt. Die flüssigkeitsähnliche Beschaffenheit von membranlosen Organellen lässt daher auf vielfältige Wechselwirkungen zwischen solchen Tröpfchen und anderen Strukturen in der Zelle schließen. In dieser Arbeit haben wir neue statistische Methoden und physikalische Theorien entwickelt, um solche Phänomene zu erforschen und wenden sie auf die Wechselwirkungen von Stress Granules, einer membranlosen Organelle, mit den Komponenten des Zytoskeletts an. Die Mikroskopie ist ein wichtiges experimentelles Instrument zur Untersuchung lebender Zellen. Allerdings ist es aufgrund der äußerst komplexen und schwankenden Umgebung in der Zelle sehr schwierig aussagekräftige Informationen auf der Grundlage einzelner Bilder zu extrahieren. Zudem sind Bilder von verschiedenen Zellen oft nicht vergleichbar. Um dieses Problem zu überwinden, stellen wir eine neuartige Bildanalysemethode vor, die diese Herausforderungen durch die Bildung aussagekräftiger Mittelwerte und Referenzzustände meistert. Mit diesen neu entwickelten Werkzeugen finden wir heraus, dass das Mikrotubuli-Netzwerk, das eine der Hauptkomponenten des Zytoskeletts ist, in der Nähe von Stress Granules wesentlich dichter ist. Wenn Mikrotubuli depolymerisiert werden, haften ihre molekularen Bausteine an der Oberfläche von Stress Granules. Wir erfassen diese experimentelle Beobachtung in einem thermodynamischen Modell der Verteilung von Partikeln auf der Oberfläche und im Volumen zweier flüssiger Phasen. Daten und Theorie belegen eine schwache (kleiner als kT) Affinität der Mikrotubuli-Bausteine für Stress Granule-Grenzflächen. Mit der Polymerisation der Mikrotubuli nimmt ihre Affinität zu den Grenzflächen zu, was zu einer ausreichenden Adhäsion führt, um Tröpfchen und/oder das Mikrotubuli-Netzwerk zu verformen. Wir validieren dieses grundlegende physikalische Phänomen in vitro durch die Interaktion eines einfachen Protein-RNA- Kondensats mit Mikrotubuli und ihren Bausteinen. Unsere Arbeit deutet darauf hin, dass Proteine und andere Objekte in der Zelle eine unspezifische Affinität für Tröpfchenoberflächen haben, die mit der Kontaktfläche zunimmt und am deutlichsten wird, wenn Partikel keine Präferenz für das Innere eines Tröpfchens gegenüber dem Rest des Zytoplasmas haben. Ein weiterer wesentlicher Bestandteil des Zytoskeletts ist Aktin, welches dynamische Netzwerke bildet, die einen konstanten Umsatz und Fluss aufweisen, was für die Zellmotilität wichtig ist. Ähnliche Analysen wie bei den Mikrotubuli zeigen abstoßende Wechselwirkungen zwischen Stress Granules und Aktin. Darüber hinaus stellen wir fest, dass die Bewegung von Stress Granules mit dem Fluss des Aktinnetzwerks korreliert ist und dass die hydrodynamische Kopplung von Stress Granules und Aktin zu einem gerichteten Transport in Richtung des Zellkerns führt. Zusammengenommen zeichnen unsere Ergebnisse ein umfassendes Bild der Interaktionen von Stress Granules mit filamentösem Aktin und Mikrotubuli. Stress Granules werden sowohl durch benetzungsvermittelte Wechselwirkungen mit Mikrotubuli als auch durch hydrodynamische Kopplung an den Aktinfluss beeinflusst. Beide physikalischen Mechanismen sind unspezifisch und sollten daher auch auf andere membranlose Organellen und Strukturen in der Zelle übertragbar sein.

Most existing approaches for flexible and stretchable electronics are based on directly bonding semiconductor devices onto stretchable substrates. They require fragile 3D interconnects, stretchable conducting polymeric materials, or liquid metals to accommodate mechanical deformation while often providing limited optoelectronic functionality and mechanical robustness. An intriguing alternative strategy for realizing flexible electronics is to integrate brittle semiconductor chips onto flexible substrates using capillary confined microscale liquid bridges as mechanical interfaces. This approach allows the use of standard electronic or optoelectronic devices fabricated on “thick” substrates as opposed to simplified circuits built on highly customized ultra-thin semiconductor membranes.For the first part of this thesis, studies on the statics and dynamics of the liquid based mechanical interface for rigid devices are present. We first introduce a design of the mechanical interface using capillary confined microscale liquid bridges between a rigid component and a flexible substrate. Numerical modeling methods are developed and are validated by corresponding experiments to precisely predict the liquid bridge topologies, capillary forces under various loading conditions. This work establishes the engineering and scientific foundation for fabrication and optimization of such liquid interfaces for flexible electronics in future research.We then continue to investigate the dynamics of such mechanical liquid interfaces. A liquid bridge is the basic element of the mechanical liquid interface. The dynamic behaviors of a liquid bridge confined between two coaxial disks are comprehensively investigated through a combined modeling and experimental study. The effects of the stretching velocity, liquid properties, and liquid volume on the dynamics of liquid bridges are systematically studied to provide a direct experimental validation of our numerical model as well as offer further physical insights for stretching velocities as high as 3 m/s.We also present a numerical modeling approach that fully captures the dynamics of a capillary self-alignment process, where a solid object floating on a liquid bridge is aligned by capillary forces of the underlying liquid bridge onto the target position. By directly coupling fluid dynamics, solid mechanics along with the additional line friction from moving contact line, model predictions have shown good agreement with experimental measurements. This work provides an experimentally validated modeling approach and physical insights to help establish foundation for systematic further studies and applications of capillary self-alignment and other related applications of the mechanical liquid interfaces.The second part of this thesis discusses the applications, designs and experimental characterizations of such mechanical interface for flexible devices. We introduce a design concept for a deployable planar microdevice based on a thin film liquid bridge and the modeling and experimental validation of its mechanical behaviors. We develop and experimentally validate theoretical models based on the energy minimization approach to examine the conformality and figures of merit of the device. This study establishes an early foundation for the mechanical design of this and related deployable planar microdevice concepts.We lastly present a tunable platform for incorporating flexible and yet non-stretching device layers on a hemispherical structure. A mechanical model is developed to elucidate the dependence of the conformality of the petal structures on their elastic modulus and thickness and the liquid surface tension. This platform will enable facile integration of non-stretching electronic and optoelectronic components prepared using established planar fabrication techniques on tunable hemispherical surfaces.

International audience; Spherical particles at a liquid interface attract each other and aggregate. The capillary forces at play are well described for a pair of objects, but as soon as many particles interact, no direct calculation is possible and only a statistical approach can account for the global dynamics. Here, we focus on the statistics of clustering of such a system with a long-range interaction which varies during the aggregation process. We measure experimentally and numerically the distribution of sizes as a function of time and exhibit a self-similar clustering mechanism subdivided into two aggregating regimes, with a well-defined transition that we characterize.

When small objects are placed at a water–air interface, attractive and repulsive interactions appear due to liquid deformations. Although it is commonly admitted that two floating objects deforming the liquid interface in the same way are only attracting, we show that in the case of objects whose height does not vary during the interaction, the situation is much more complex than expected. In fact, attraction and repulsion can coexist at different ranges, so that equilibrium distances are observed. A 1D model based on the capillary interaction between vertical plates immersed in water is used to illustrate and calculate these situations, giving a picture of capillary interactions. We show that the wetting condition plays a determinant role in the behaviour of the interaction between floating objects. We also demonstrate that the equilibrium distance is given by the logarithm of the capillary charge ratio, using the right capillary charge definition. We also discuss the particular case of the existence of an interaction with a zero-capillary charge. A general equation of the equilibrium distance is proposed. An experimental confirmation of this relation is also given.

Study question Can the gas-liquid interface organ culture system that achieved in vitro spermatogenesis in mice also support in vitro spermatogenesis in human adult testis? Summary answer Although the progression of spermatogenesis was not observed, germ cells were maintained without the degeneration of the architecture in both fresh and cryopreserved testicular tissues. What is known already Although the research on in vitro spermatogenesis have been conducted for 100 years, only the organ culture system using gas-liquid interface method achieved in vitro spermatogenesis in mice. It has not been verified whether this culture system can be applied to other mammals including humans and induce spermatogenesis. Study design, size, duration Testicular tissue was obtained from the transgender patients receiving sex reassignment surgery. Testicular specimens were either immediately processed for cultivation or cryopreserved, using a vitrification freezing protocol. Organ culture of testicular fragments was performed in three different media for a maximum period of 3 weeks to evaluate the short-term changes in the cultured tissues (viability, proliferation and maintenance of germ and somatic cells). Participants/materials, setting, methods Fresh and cryopreserved-thawed testis fragments (1–2 mm3) were cultured using the organ culture system in alpha-MEM with knock-out serum replacement (K group), alpha-MEM with lipid-rich BSA (A group) and DMEM with FBS (D group). Luteinizing hormone, follicle stimulating hormone and testosterone were supplemented. The number of germ cells (using DDX4), proliferative activity of germ cells (using EdU assay) and intratubular cell apoptosis (by TdT-mediated dUTP Nick End Labeling) were evaluated by immunohistochemical staining weekly. Main results and the role of chance The architecture of the seminiferous tubules was maintained until the second week of culture in both the fresh and the cryopreserved culture group. The number of DDX4-positive germ cells per seminiferous tubule in groups D, K, and A was 49 ± 24, 55 ± 21, 50 ± 26 cells/tubule in 1 day, 32 ± 13, 42 ± 7, 36 ± 21 cells/tubule in 1week, respectively. The numbers gradually decreased to 26 ± 8, 24 ± 6 and 27 ± 18 cells/tubule, in 2 weeks, respectively, with no difference among the groups. The number of intratubular EdU-positive cells of groups D, K, and A was 0.2 ± 0.2, 2.8 ± 2.1, 1.1 ± 0.8 cells/tubule at 1 day, 0.1 ± 0.2, 0.5 ± 0.6, 0.3 ± 0.6 cells/tubule at 1 week, respectively. The values were 0.01, 0.05, and 0.03 at 2 weeks. Thus, EdU-positive cells drastically decreased from the first week of culture. The number of DDX4-positive germ cells and the intratubular EdU-positive cells in the cryopreserved culture group was not different from that in the fresh culture group. Limitations, reasons for caution Current organ culture systems are incomplete, being unable to induce human in vitro spermatogenesis. Further research is needed to improve culture condition with the aim of producing fertile sperm of infertile adult male patients. Wider implications of the findings: Our organ culture system could maintain testis structure and germ cells. By using the testis tissues of the transgender patients, which are available with their consent, we will promote the investigation of the culture condition necessary for germ cell proliferation and differentiation. Trial registration number Grant-in-Aid for Scientific Research on Innovative Areas 18H05546, Grant-in-Aid for Young Scientists (A) 17H05098 and Takeda Science Foundation

Nature often provides unique and elegant solutions for solving engineering problems. For example, cactus, desert grass, and Nepenthes alata have provided inspirations for the design of fog-collection and water-transportation devices. Here, a bioinspired hybrid fog collector consisting of cactus-inspired spines featuring longitudinal ridges on the surfaces and peristome-inspired bottom channels decorated with curved inclined arc-pitted grooves (C-IAPGs) is developed. Experimentally, the fog collector was fabricated by custom-made micro-continuous liquid interface printing with a resolution of 6.9 μm·pixel-1 and a speed of up to 125 μm·s-1. Characterization results show that the printed spines with four longitudinal ridges manifest the maximum fog-collection rate, and the bottom channel with C-IAPGs can efficiently transport the water droplets into the reservoir. This work is believed to be beneficial for developing next-generation fog-collection, water-transportation, and desalination devices.

The overuse of antibiotics in today's society has resulted in high concentrations of pharmaceutical contaminants in the natural environment. In this work, we investigated the surfactant-mediated adsorption of fluoroquinolone (FQ) antibiotics at the gas-liquid interface and their separation using a semi-batch foam fractionation process. FQs being a zwitterionic compound have an affinity to bind with both cationic and anionic surfactants. The adsorption of FQs to the gas-liquid interface was investigated using a cationic cetyltrimethylammonium bromide (CTAB) and anionic sodium dodecyl sulfate (SDS) surfactant. Ciprofloxacin (CF) was chosen as a model FQ antibiotic. The adsorption properties of the surfactant systems and CF were characterized using pendant-drop tensiometry and surface excess analysis. It was found that CF partitions to the gas-liquid interface more readily in the presence of SDS compared to CTAB. This was also corroborated in the foam fractionation experiments. At optimum operating conditions, CF showed a higher removal efficiency with SDS (96.3%) compared to CTAB (52%). In spite of strong molecular interactions between CTAB and CF, the preferential adsorption of DS

Experimental investigations on microsegregation during directional solidification of two Al–Cu alloys with and without a steady magnetic field (SMF) were carried out. The solidification morphologies and microsegregation behaviors were examined. The amount of non-equilibrium eutectics and the concentration versus solid fraction profiles were obtained. The results indicated that the amount of microsegregation was increased under an SMF when the solid/liquid interface was planar. For cellular and dendritic growth, however, the SMF alleviated the microsegregation level. The change of the factors affecting microsegregation under the SMF was analyzed. The reduction in solid diffusion coefficient in an SMF aggravated the microsegregation level, while the thermoelectric magnetic convection (TEMC) was found to have a positive effect. It was concluded that the change in microsegregation in different conditions might be attributed to the combined action of solid diffusion suppression and TEMC in mushy zone under an SMF. Based on Brody model, the microsegregation behavior in an SMF was predicted. The calculated results were in agreement with experiment observations.

Increasing applications of multiwalled carbon nanotubes (MWCNT) lead to significant occupational exposure and potential health concerns. Toxicity of MWCNT should be carefully elucidated since the conventional (CON) method with fully immersed condition fails to mimic the air–liquid interface (ALI) in airways. Additionally, quantification of MWCNT in cells was a real challenge. Currently available ALI exposure devices are costly, posing problems to conducting in vitro evaluations for emerging nanomaterials. A novel system, consisting of a shaker fluidized-bed atomizer (SFA) and electrostatic shallow liquid interface (ESLI) exposure chamber, has been developed for investigating nanotoxicity of well-dispersed pristine-MWCNT (pMWCNT) and carboxylized-MWCNT (cMWCNT). After 24-h exposure, LDH, MCP-1, IL-1β, IL-6, and TNF-α releases were determined, and cell uptakes were quantified according to the molybdenum content in cells. Biological responses triggered by SLI exposure are obviously more sensitive compared wi...

The accurate prediction of hydrate film thickness is critical for addressing the hydrate-related issues in the fields of environment and energy resource, including the disposal of greenhouse gases ...

In the present study, oxygen mass-transfer processes through the liquid-air interface fromgas mixture with variable volume at constant pressure were investigated. This paperdescribes a device based on the electrochemical oxygen sensor placed on the liquid-airsurface. The oxygen sensor measured the decrease of oxygen concentration in the smallvolume under the device, that is in contact with deoxygenated liquid. Experimental dataobtained by the device were introduced to a novel mathematical model, which allowedcalculating diffusion flow through the liquid-air interface and diffusional conductivity P/1of liquid surface.By means of the developed device it is possible to measure the total impediment of theair-water interface to oxygen mass-transfer.

Separation and recycling of rare-earths using ionic liquids as extractant are becoming a promising approach to replace traditional volatile organic solvents in recent years. Generally, the addition of some special salts could improve the extraction efficiency of rare-earths by numerous non-functional ionic liquids. However, knowledge behind the nature of the salt effect is limited. Here, we found that the enhancement in the extraction of rare-earth ions, Pr3+ ions, using non-functional ionic liquid, [A336][NO3] (Tricaprylmethylammonium nitrate) was driven by the synergism of Hofmeister bias and complexation behaviors of salt anions with Pr3+ ions. Molecular dynamic simulations offered a new insight into the interaction mechanism of the ionic liquid with Pr3+ ions at liquid/liquid interface. It was revealed that salt anions could perform as a bridge to connect Pr3+ ions and the ionic liquid, so that promoted the extraction of Pr3+ ions. Therefore, the strong complexation ability of salt anions with Pr3+ ions and poor hydration of salt anions faciliated the transport of Pr3+ ions across liquid/liquid interface.

Superhydrophobic carbon nanotube (CNT) films have attracted extensive research attention because of the superior CNT properties that have a significant impact on the mass/energy transfer at the CNT/liquid interface. Until now, most reported methods for producing superhydrophobic CNT films require multiple steps, making the fabrication process very complicated and time-consuming, and may deteriorate the CNT intrinsic properties. In this study, superhydrophobic CNT films composed of short CNT strands were fabricated through a single-step chemical vapor deposition method on various types of supports, including hollow fiber and disc supports. Attributed to its firm structure, this durable superhydrophobic film could withstand water invasion and show promising stability and renewability during a 4-week wettability test. Benefiting from the preservation of CNT properties without post modifications, the film exhibited excellent chemical robustness to corrosive liquids from pH = 0–14. In addition, the application...

Biomimetic lubricant-infused surfaces are developed as an effective approach to solve the problem of biofouling. Herein, lubricant-infused surfaces were fabricated on various structured surfaces with polished, nanostructured, microstructured, and micro/nanostructured features. The influences of surface topographies on their infused configurations, stability and antifouling performance were studied in detail. The results indicated that the structures played a decisive role in the formation of lubricant-infused surfaces. Infused configurations of lubricant were various responded to the different structures, including floated on polished surfaces, encapsulated on nanostructured surfaces, impregnated with emergent features on microstructured surfaces and impregnated/encapsulated on micro/nanostructured surfaces. Stability and antifouling performance were decided by the infused configurations. The encapsulated lubricant entrapped by a capillary force in nanostructures can form a continuous liquid interface to retain stability and provide antifouling performance. The results would show great potential for the construction of antifouling coatings by lubricant-infused techniques.

Photoelectrochemistry is a promising approach for converting solar energy to storable chemical energy in chemical fuels. The efficiency of photoelectrochemcial devices depends critically on efficient transfer of charge carrier across the electrode liquid interface and the efficiency and selectivity of the catalytic reaction on electrode surface. Although transient absorption spectroscopy is a powerful tool for probing interfacial dynamics in high surface area electrodes, it is often not applicable on planar electrodes because the observed signal is often dominated by carrier dynamics in the bulk. In this talk, we discuss our recent effort in developing in situ time-resolved linear and nonlinear spectroscopic tools that can be used to probe carrier dynamics and reactions at planar electrode/liquid interfaces, focusing on transient reflection spectroscopy and electric field induced second harmonic generation (EFISH) spectroscopy. Compared to transient absorption, transient reflection spectroscopy is more sensitive to surface carrier density that can be more directly correlated to catalysis. We showed that transient reflectance change can be used to follow charge carrier dynamics and their amplitude can be directly correlated to efficiency of initial interfacial charge separation on p-GaP single crystals protected by TiO2 ALD layer. Our finding suggests that IPCE is determined by the product of the efficiency of initial ultrafast (< hundreds of ps) charge separation across the GaP/TiO2 interface and the efficiency of water reduction reaction on the slower time scale. Key loss pathways that limit these efficiencies are discussed. In a second approach, we showed the EFISH signal in a n-doped single crystal TiO2 can be used to probe the accumulation of photogenerated carriers at surface states and these trapped carriers are responsible for the water oxidation reaction.

A liquid marble (LM) is a droplet coated with microparticles that isolate the liquid interior from its surroundings, making it perfectly non-wetting. This attractive feature allows the LM to perform useful tasks such as coalescence, targeted delivery, and controlled release. The non-wetting characteristic also allows the LM to float on a carrier liquid. The growing number of applications in digital microfluidics requires further insights into the fundamental properties of a LM such as its effective surface tension. Although the coating provides the LM with various desirable characteristics, its random construction presents a major obstacle to accurate optical analysis. This paper presents a novel method to measure the effective surface tension of a floating LM using X-ray imaging and curve fitting procedures. X-ray imaging reveals the true LM liquid-air interface hidden by the coating particles. Analysis of this interface showed that the effective surface tension of a LM is not significantly different from that of its liquid content. This indicates that the particle coating might not have significantly altered the behaviour of the liquid interface. We also found that our method is sensitive enough to detect the variations across individual LMs.

PURPOSE To evaluate the effects of femtosecond laser-assisted keratoplasty using a liquid patient interface (L-PI) as opposed to an applanated interface (A-PI) on graft quality and functionality markers. METHODS Pressure measurements during femtosecond laser-assisted trephination were performed using two groups of 10 porcine eyes. Trephination was performed either in an L-PI or in an A-PI setting. Pressure sensor needles placed intravitreally continuously recorded intraocular pressure during trephination. Twenty paired human donor eyes were used to test the morphological quality of donor tissue after trephination in L-PI and A-PI settings. Optical coherence tomography (OCT) scans were performed before and after trephination. Images were processed using ImageJ and pixel2 . RESULTS During trephination, pressure measurements with an L-PI were significantly lower than with an A-PI (p = 0.0121). Mean pressure during trephination was 78.1 mmHg ± 37.6 mmHg with L-PI and 188.6 mmHg ± 17.7 mmHg with A-PI. Trephination in A-PI produced a significantly larger increase (p

In this paper, an optofluidic phase modulator based on dielectrowetting is designed and fabricated to adjust the optical phase. Two liquids are filled in the device, and a transparent sheet is employed at the liquid interface to keep the interface flat. When different voltages are applied to the modulator, the flat interface moves up and down, leading to the variation of the optical phase. A theoretical model is constructed to predict the optical phase shift quantitatively, and the phase regulation ability is also tested experimentally. Our modulator realizes continuous adjustment of the optical phase in a certain range by the operation of voltage adjustment. When the voltage is increased to 150 V, the optical phase modulation range of our proposed modulator can reach 9.366 π.

This paper addresses the operation in microgravity of the surface reconstruction device whose design is detailed in the first part of the manuscript. The system, employed during the drop tower campaign of the UNOOSA DropTES 2019 StELIUM experiment, studies the axisymmetric and lateral oscillations of a ferrofluid solution in microgravity. The free liquid surface is reconstructed in a cylindrical tank and relevant metrics of the magnetic sloshing problem, such as contact angles, hysteresis parameters, natural oscillation frequencies, or damping ratios, are derived. The result is a rich and unique database where several phenomena of scientific and technological interest are reported for the first time. The dependence of the fundamental axisymmetric and lateral modal frequencies with the applied magnetic field is consistent with the literature and past experiments. Although the detection system was designed and built using low-cost hardware, high-quality results are obtained.

Monolayers of soft colloidal particles confined at fluid interfaces are at the core of a broad range of technological processes, from the stabilization of responsive foams and emulsions to advanced lithographic techniques. However, establishing a fundamental relation between their internal architecture, which is controlled during synthesis, and their structural and mechanical properties upon interfacial confinement remains an elusive task. To address this open issue, which defines the monolayer's properties, we synthesize core-shell microgels, whose soft core can be chemically degraded in a controlled fashion. This strategy allows us to obtain a series of particles ranging from analogues of standard batch-synthesized microgels to completely hollow ones after total core removal. Combined experimental and numerical results show that our hollow particles have a thin and deformable shell, leading to a temperature-responsive collapse of the internal cavity and a complete flattening after adsorption at a fluid interface. Mechanical characterization shows that a critical degree of core removal is required to obtain soft disk-like particles at an oil-water interface, which present a distinct response to compression. At low packing fractions, the mechanical response of the monolayer is dominated by the outer polymer chains forming a corona surrounding the particles within the interfacial plane, regardless of the presence of a core. By contrast, at high compression, the absence of a core enables the particles to deform in the direction orthogonal to the interface and to be continuously compressed without altering the monolayer structure. These findings show how fine, single-particle architectural control during synthesis can be engineered to determine the interfacial behavior of microgels, enabling one to link particle conformation with the resulting material properties., ACS Nano, 15 (8), ISSN:1936-0851, ISSN:1936-086X

This paper describes an inexpensive, non-invasive and highly adaptable surface reconstruction device for opaque liquids. The instrument was developed to study the lateral sloshing of ferrofluids in microgravity as part of the UNOOSA DropTES 2019 StELIUM project. Its design is driven by the geometrical and mechanical constraints imposed by ZARM’s drop tower, where the experiment was launched in November 2019. The launch catapult and deceleration systems impose strong axial g-loads to a system that is confined in the reduced capsule environment. Redundant procedures are implemented to measure the first two lateral sloshing frequencies and damping ratios of the magnetic liquid, as well as its equilibrium surface in microgravity. Ideal vertical resolutions between 0.25 and 0.4 mm/px can be achieved with the configuration here proposed. The final performance depends, among other factors, on the correct application of the robust calibration procedure that is documented in this work.

Near total reflection regime has been widely used in X-ray science, specifically in grazing incidence small angle X-ray scattering and in hard X-ray photoelectron spectroscopy. In this work, we introduce some practical aspects of using near total reflection in ambient pressure X-ray photoelectron spectroscopy and apply this technique to study chemical concentration gradients in a substrate/photoresist system. Experimental data are accompanied by X-ray optical and photoemission simulations to quantitatively probe the photoresist and the interface with the depth accuracy of ~1 nm. Together, our calculations and experiments confirm that near total reflection X-ray photoelectron spectroscopy is a suitable method to extract information from buried interfaces with highest depth-resolution, which can help address open research questions regarding our understanding of concentration profiles, electrical gradients, and charge transfer phenomena at such interfaces. The presented methodology is especially attractive for solid/liquid interface studies, since it provides all the strengths of a Bragg-reflection standing-wave spectroscopy without the need of an artificial multilayer mirror serving as a standing wave generator, thus dramatically simplifying the sample synthesis., Comment: 13 pages, 4 figures Supplemental Information

A CoCrCuFeNiTi0.8 high-entropy alloy was prepared using directional solidification techniques at different withdrawal rates (50 &mu, m/s, 100 &mu, m/s, 500 &mu, m/s). The results showed that the microstructure was dendritic at all withdrawal rates. As the withdrawal rate increased, the dendrite orientation become uniform. Additionally, the accumulation of Cr and Ti elements at the solid/liquid interface caused the formation of dendrites. Through the measurement of the primary dendrite spacing (&lambda, 1) and the secondary dendrite spacing (&lambda, 2), it was concluded that the dendrite structure was obviously refined with the increase in the withdrawal rate to 500 &mu, m/s. The maximum compressive strength reached 1449.8 MPa, and the maximum hardness was 520 HV. Moreover, the plastic strain of the alloy without directional solidification was 2.11%, while the plastic strain of directional solidification was 12.57% at 500 &mu, m/s. It has been proved that directional solidification technology can effectively improve the mechanical properties of the CoCrCuFeNiTi0.8 high-entropy alloy.

We investigated the evaporation and condensation coefficients of vapor, which represent evaporation and condensation rates of vapor molecules, under high gas pressure (high gas density) conditions in a system of a vapor/gas-liquid equilibrium state. The mixture gas is composed of condensable gas (vapor) and non-condensable gas (NC gas) molecules. We performed numerical simulations of vapor/gas–liquid equilibrium systems with the Enskog–Vlasov direct simulation Monte Carlo (EVDSMC) method. As a result of the simulations, we found that the evaporation and condensation fluxes decrease with increasing NC gas pressure, which leads to a decrease in the evaporation and condensation coefficients of vapor molecules. Especially, under extremely high gas pressure conditions, the values of these coefficients are close to zero, which means the vapor molecules cannot evaporate and condensate at the interface. Moreover, we found that the vapor molecules behave as NC gas molecules under high gas pressure conditions. We also discussed the reason why NC gas molecules interfere with evaporation and condensation of vapor molecules at the vapor/gas–liquid interface.

Under pure diffusive growth conditions, layered peritectic solidification is possible. In reality, the competitive growth of the primary &alpha, phase and the peritectic &beta, phase revealed some complex peritectic solidification morphologies due to thermo-solutal convection. The binary organic components Tris-(hydroxylmenthyl) aminomethane-(Neopentylglycol) were used as a model system for metal-like solidification. The transparency of the high-temperature non-faceted phases allows for the studying of the dynamic of the solid/liquid interface that lead to peritectic solidification morphologies. Investigations were carried out by using the Bridgman technic for process conditions where one or both phases solidify in a non-planar manner. Different growth conditions were observed, leeding to competitive peritectic growth morphologies. Additionally, the competitive growth was solved numerically to interpret the observed transparent solidification patterns.

Soft and flexible two-dimensional (2D) systems, such as liquid interfaces, would have much more potentials in dynamic regulation on nano-macro connected functions. In this Minireview article, we focus especially on dynamic motional functions at liquid dynamic interfaces as 2D material systems. Several recent examples are selected to be explained for overviewing features and importance of dynamic soft interfaces in a wide range of action systems. The exemplified research systems are mainly classified into three categories: (i) control of microobjects with motional regulations; (ii) control of molecular machines with functions of target discrimination and optical outputs; (iii) control of living cells including molecular machine functions at cell membranes and cell/biomolecular behaviors at liquid interface. Sciences on soft 2D media with motional freedom and their nanoarchitectonics constructions will have increased importance in future technology in addition to popular rigid solid 2D materials.

To introduce a methodical description and to investigate first clinical safety of a novel liquid interface technology for femtosecond laser-assisted perforating keratoplasty, maintaining the corneal curvature without applanation of the cornea.In this pilot study six patients received a femtosecond laser keratoplasty using a new liquid interface providing a non-applanating trephination. Clinical outcomes were evaluated 1, 3 and 6 months after surgery.All procedures were performed without complications and donor and recipient corneas could be aligned without problems, even in cases of advanced keratoconus. Although this initial pilot study investigated clinical safety, a positive effect on postoperative astigmatism was observed.We could show in this first pilot study that a hand-held liquid patient interface in combination with a femtosecond laser has a preliminary safety and reliability in penetrating keratoplasty.

Nanomaterials are of much interest and are considered as efficient adsorbents for wastewater treatment because of their small particle sizes, large specific surface areas, abundant reactive sites, and nanostructures. In this chapter, the adsorption phenomena at the solid/liquid interface are outlined, together with the most commonly used theoretical adsorption models, their limitations, and some kinetics models. A wide range of organic and inorganic pollutants, with dyes, pesticides and herbicides, heavy metals, radio nuclides, drugs, and other emerging contaminants, lead to a serious concern about human health and aquatic ecosystem and can be treated using adsorption processes. Depending on the targeted contaminants, adsorption techniques take advantages of various types of metal oxides, metal nanoparticles, and carbon-based materials. Finally, some perspectives of the use of nanoadsorbents are pointed out, with the key points related to the cost of the development of such technologies, their practical applications, and the shortcomings of the nanoeffect, such as their transport in aqueous media and the toxicology.

Titanium dioxide exhibits superior photocatalytic properties, mainly occurring in liquid environments through molecular adsorptions and dissociations at the solid/liquid interface. The presence of these wet environments is often neglected when performing ab initio calculations for the interaction between the adsorbed molecules and the TiO 2 surface. In this study, we consider two solvents, that is, water and ethanol, and show that the proper inclusion of the wet environment in the methodological scheme is fundamental for obtaining reliable results. Our calculations are based on structure predictions at a density functional theory level for molecules interacting with the perfect and defective anatase (101) surface under both vacuum and wet conditions. A soft-sphere implicit solvation model is used to describe the polar character of the two solvents. As a result, we find that surface oxygen vacancies become energetically favorable with respect to subsurface vacancies at the solid/liquid interface. This aspect is confirmed by ab initio molecular dynamics simulations with explicit water molecules. Ethanol molecules are able to strongly passivate these vacancies, whereas water molecules only weakly interact with the (101) surface, allowing the coexistence of surface vacancy defects and adsorbed species. The infrared and photoluminescence spectra of anatase nanoparticles predominantly exposing (101) surfaces dispersed in water and ethanol support the predicted molecule-surface interactions, validating the whole computational paradigm. The combined analysis allows for a better interpretation of TiO 2 processes in wet environments based on improved computational models with implicit solvation features.

We developed a new method for removing gaseous substances by using high frequency (200 kHz) ultrasonic irradiation of water, and the effects of ultrasonic irradiation on gas-phase toluene were evaluated quantitatively for the first time. The removal ratio of gaseous toluene increased with increasing ultrasonic power, but the reaction was inhibited by the addition of radical scavengers, indicating that ultrasonic irradiation not only accelerated the dissolution of gaseous toluene but also induced toluene decomposition. The contribution made by OH radicals to the decomposition of gaseous toluene at the gas–liquid interface was confirmed by the difference in removal ratios between addition of KI and addition of tert-butyl alcohol. The toluene removal mechanism was investigated by studying the logarithmic plots for toluene concentration at specified times. The results of this study clearly showed the promotion of gaseous toluene dissolution and the reaction via OH radicals at the gas–liquid interface by sonophysical and sonochemical effects with both effects contributing to the removal of gaseous toluene. Furthermore, the total organic carbon concentration in the aqueous phase increased with increasing reaction time, indicating that the toluene degradation products were trapped and decomposed into low-molecular-weight organic compounds in the aqueous phase.

This study investigated the influence of the solid cohesion, fsc, on the viscous properties (m-value and k-value in the Norton law) for aluminum alloys during partial solidification. In the previous study of Haaften (Mater. Sci. Eng. A, 336 (2002), 1–6), a constitutive model taking into account fsc was proposed as e ˙ = k (T) (σ/fsc (θ,T)) n (=1/m), where θ referred to the dihedral angle at the solid/liquid interface. However, even though it is well known that the m-value decreases with the decreasing temperature in the semi-solid state, the model defined the m-value as a constant to the temperature. Therefore, m = f(fsc) and k = g(fsc) during solidification were clarified in this study. The viscous properties were obtained by tensile tests during partial solidification for Al-5mass%Mg and Al-2mass%Cu alloys. As a result, it was found that the change in the m-value of 0 ≤ fsc

Magnetic ellipsoidal particles adsorbed at a liquid interface provide exciting opportunities for creating switchable functional materials, where self-assembly can be switched on and off using an external field [Davies et al., Adv. Mater., 2014, 26, 6715]. In order to gain a deeper understanding of this novel system in the presence of an external field, we study the capillary interaction and self-assembly of tilted ellipsoids using analytical theory and finite element simulations. We derive an analytical expression for the dipolar capillary interaction between tilted ellipsoids in elliptical polar coordinates, which exhibits a 1/r2 power law dependence in the far field (i.e., large particle separations r) and correctly captures the orientational dependence of the capillary interactions in the near field. Using this dipole potential and finite element simulations, we further analyze the energy landscape of particle clusters consisting of up to eight tilted ellipsoids in contact. For clusters of two particles, we find that the side-to-side configuration is stable, whereas the tip-to-tip configuration is unstable. However, for clusters of more than three particles, we find that circular loops of side-to-side particles become globally stable, whereas linear chains of side-to-side particles become metastable. Furthermore, the energy barrier for the linear-to-loop transition decreases with increasing particle number. Our results explain both thermodynamically and kinetically why tilted ellipsoids assemble side-to-side locally but have a strong tendency to form loops on larger length scales.

As a ubiquitous solar-thermal energy conversion process, solar-driven evaporation has attracted tremendous research attention owing to its high conversion efficiency of solar energy and transformative industrial potential. In recent years, solar-driven interfacial evaporation by localization of solar-thermal energy conversion to the air/liquid interface has been proposed as a promising alternative to conventional bulk heating-based evaporation, potentially reducing thermal losses and improving energy conversion efficiency. In this Review, we discuss the development of the key components for achieving high-performance evaporation, including solar absorbers, evaporation structures, thermal insulators and thermal concentrators, and discuss how they improve the performance of the solar-driven interfacial evaporation system. We describe the possibilities for applying this efficient solar-driven interfacial evaporation process for energy conversion applications. The exciting opportunities and challenges in both fundamental research and practical implementation of the solar-driven interfacial evaporation process are also discussed. The thermal properties of solar energy can be exploited for many applications, including evaporation. Tao et al. review recent developments in the field of solar-driven interfacial evaporation, which have enabled higher-performance structures by localizing energy conversion to the air/liquid interface.

Cooling rate is a critical factor controlling the grain size of cast metals. Generally, it is accepted that higher cooling rate leads to smaller grains due to the high undercooling achieved. However, the present work observed grain coarsening after solidification with higher cooling rate in some specific aluminium alloys. Using a V-shape cooper mould, different solidification cooling rates were achieved on the aluminium alloy ingots. It was found that the grains at the tips of the ingots, where corresponded to the highest cooling rate, were significantly coarser than the other parts of the ingots with lower cooling rate for Al-3.0 wt%Si and Al-0.1 wt%Ti alloys. However, such phenomenon was not observed in other aluminium alloys. It was believed that such grain coarsening phenomenon at fast cooling was related to both the constitutional undercooling zone ahead of the solid/liquid interface and the growth restriction factor of the solutes. The results can be well explained in terms of the interdependency theory for grain refinement of cast metals.

An improved general understanding of electrocatalytic gas evolution reactions may - besides contributing to fundamental knowledge - play a crucial role in efforts directed to energy savings during large-scale industrial electrocatalytic processes. Aside from the search for new electrocatalytically active materials, in-depth understanding of electrode surface properties may contribute to more efficient utilization of known electrocatalysts. SECM is applied in the sample generation/tip collection mode to determine the spatial distribution of electrocatalytic activity during Cl2 evolution at the solid/liquid interface of dimensionally stable anodes. Statistical interpretation of the local microscopic distribution of the electrocatalytic activity of dimensionally stable anodes was used as a basis for improved understanding of their overall electrocatalytic performance.

Expressions for the roughening transition of solid/liquid interface in multicomponent alloys are developed and a related thermodynamic model of roughening transition is proposed. The alloying and configurational entropy effects on the interface structure are discussed based on the Gibbs free energy of roughening transition. The surface roughness in alloys depends on the Gibbs free energy of phase transition and the partition coefficient.