Capillary Pumping between Droplets on Superhydrophobic Surfaces

The famous two-balloon experiment involves two identical balloons filled up with air and connected via a hollow tube, and upon onsetting the experiment one of the balloons shrinks and the other expands. Here, we present the liquid version of that experiment. We use superhydrophobic (SHP) substrates to form spherical droplets and connect them with a capillary channel. Different droplet sizes, substrates of different hydrophobicities, and various channel pathways are investigated, and morphometric parameters of the droplets are measured through image processing. In the case of SHP substrates the pumping is from the smaller droplet to the larger one, similar to the two-balloon experiment. However, if one or both of the droplets are positioned on a normal substrate the curvature radius will indicate the direction of pumping. We interpret the results by considering the Laplace pressures and the surface tension applied by the channel at the connecting points.

Design of industrial wastewater demulsifier by HLD-NAC model

The chemical method is one of the treatment techniques for the separation of oil–water emulsion systems. The selection of appropriate demulsifiers for each emulsion system is the most challenging issue. Hydrophilic-lipophilic-deviation (HLD) is a powerful semi-empirical model, providing predictive tools to formulate the emulsion and microemulsion systems. This work aims to apply HLD to obtain an optimal condition for demulsification of oil-in-water emulsion system—real industrial wastewater—with different water in oil ratios (WOR). Therefore, the oil parameter of the contaminant oil and surfactant parameter for three types of commercial surfactants were calculated by performing salinity scans. Furthermore, the net-average-curvature (NAC) framework coupled with HLD was used to predict the phase behavior of the synthetic microemulsion systems, incorporating solubilization properties, the shape of droplets, and quality of optimum formulation. The geometrical sizes of non-spherical droplets (Ld, Rd)—as an indicator of how droplet sizes are changing with HLD—were consistent with the separation results. Correlating Ld/Rd at phase transition points with bottle test results validates the hypothesis that NAC-predicted geometries and demulsification behavior are interconnected. Finally, the effect of sec-butanol was examined on both synthetic and real systems, providing reliable insights in terms of the effect of alcohol for WOR ≠ 1.

POTENTIATING MICONAZOLE ACTIVITY WITH CLOVE OIL AND CHITOSAN IN MICROEMULSION BASED GEL FOR TREATMENT OF FUNGAL INFECTION

The study aimed to investigate the in vitro antifungal activity of miconazole entrapped in microemulsion based gel with clove oil as permeation enhancer and chitosan as antifungal agent. SEM confirmed spherical droplets of microemulsion in the 2 micron size range. The viscosity of emugel was 2251 cP, excellent spreadability 31.27 ±0.219 g.cm/cc as compared to marketed formulation. pH was 5.528 ± 0.032, homogeneity was excellent and drug content was 98 % in optimized batch. No drug-excipients interaction was reported in FTIR spectroscopy. In vitro drug release showed 94.8 % in 6 h. Ex vivo skin permeation showed higher steady state flux than conventional cream. Antifungal activity on Candida albicans showed a zone of inhibition more than that of marketed preparation. Thus, it can be concluded that the formulation may hold some promise for the treatment of severe fungal infections.

Microfluidic on-chip Production of Alginate Hydrogels Using Double Co-flow Geometry

Microfluidic on-chip production of microgels employing external gelation has numerous biological and pharmaceutical applications, particularly for the encapsulation of delicate cargos, however, the on-chip production of microgels in microfluidic devices can be challenging due to problems such as clogging caused by accelerated progress in precursor solution viscosity. Here, we introduce a novel microfluidic design incorporating two consecutive co-flow geometries for microfluidic droplet generation. A shielding oil phase is employed to avoid emulsification and gelation stages from occurring simultaneously, thereby preventing clogging. The results revealed that the microfluidic device could generate highly monodispersed spherical droplets (coefficient of variation < 3%) with an average diameter in the range of 60–200 μm. Additionally, it was demonstrated that the device could appropriately create a shelter of the oil phase around the inner aqueous phase regardless of the droplet formation regime and flow conditions. The ability of the proposed microfluidic device in the generation of microgels was validated by producing alginate microgels utilizing an aqueous solution of calcium chloride as the continuous phase.

Interactions between Phase-Separated Liquids and Membrane Surfaces

Liquid-liquid phase separation has recently emerged as an important fundamental organizational phenomenon in biological settings. Most studies of biological phase separation have focused on droplets that “condense” from solution above a critical concentration, forming so-called “membraneless organelles” suspended in solution. However, membranes are ubiquitous throughout cells, and many biomolecular condensates interact with membrane surfaces. Such membrane-associated phase-separated systems range from clusters of integral or peripheral membrane proteins in the plane of the membrane to free, spherical droplets wetting membrane surfaces to droplets containing small lipid vesicles. In this review, we consider phase-separated liquids that interact with membrane surfaces and we discuss the consequences of those interactions. The physical properties of distinct liquid phases in contact with bilayers can reshape the membrane, and liquid-liquid phase separation can construct membrane-associated protein structures, modulate their function, and organize collections of lipid vesicles dynamically. We summarize the common phenomena that arise in these systems of liquid phases and membranes.

Concentric/Bipolar Ordering of Liquid Crystalline Graphene Oxide Nanosheets Confined in Microfluidically Synthesized Spherical Droplets

Liquid crystalline (LC) two-dimensional (2D) nanomaterials have been exploited for designing exquisitely assembled structures or for reinforcing LC properties in a mix with conventional LC materials. Graphene oxide (GO) nanosheets...

Frustrated Structures and Pattern Formation After Thermal Quenches in Cholesteric Liquid Crystal Droplets

The complex arrangement of layered structures in curved geometries is a ubiquitous problem in soft condensed matter systems. In general, cholesteric liquid crystals (CLCs) in spherical droplets have been studied...

Efek Bentonit pada Karakteristik Pembakaran Droplet Biodiesel Kelapa Sawit

The blends of fuel to base liquid fuels for the enhancement of combustion properties has long generated interest since it is linked to improvement in combustion properties in biodiesel fuels. This work investigates the effect of bentonite nanoparticles on the combustion characteristics of palm oil biodiesel. These nanoparticles are added in various compositions on biodiesel which are 0% (B0), 10% (B10), 20% (B20) and 30% (B30). The insulin pen was used to make Sub-millimeter-sized spherical droplets, and the combustion process of droplets was recorded using a camera in atmosphere condition. The fuel was dripped on the tip of the thermocouple junction and ignited using a torch of the butane-air mixture on a cylindrical burner. Properties such as ignition delay, burning rate, and flame temperature of droplets were measured with post-processing of the resulting images. The results showed a decrease in ignition delay and an increase of flame temperature with the increase of bentonite percentage due to bentonite acts as a catalyst capable of accelerating the reaction rate. However, the burning rate decrease with the increasing of bentonite percentage due to the oxygen content of the mixture is getting lower.

Percus–Yevick structure factors made simple

Measuring the structure factor, S(q), of a dispersion of particles by small-angle X-ray scattering provides a unique method to investigate the spatial arrangement of colloidal particles. However, it is impossible to find the exact location of the particles from S(q) because some information is inherently lacking in the measured signal. The two standard ways to analyse an experimental S(q) are then to compare it either with structure factors computed from simulated systems or with analytical ones calculated from approximated systems. However, such approaches may prove inadequate for dispersions of variously polydisperse particles. While Vrij, Bloom and Stell established a mean-field approach that could yield fairly accurate approximations for experimental S(q), this solution has remained underused because of its mathematical complexity. In the present work, the complete Percus–Yevick solution for general polydisperse hard-sphere systems is derived in a concise form that is straightforward to use. The form of the solution has been simplified enough to provide experimentalists with ready solutions of several commonly encountered particle-radius distributions in real systems (Schulz, truncated normal and inverse Gaussian). The approach is also illustrated with a case study of the exponential radius distribution. Finally, the application of the proposed solution to the power-law radius distribution is discussed in detail by comparing the calculations with experimentally measured S(q) for an Apollonian packing of spherical droplets recently reported in high-internal-phase-ratio emulsions.