Air-liquid Surface Research Articles

Control Patterning of Cyanobiphenyl Liquid Crystals for Electricity Applications.

Controlling molecular self-assembly from organic solution evaporation is an important strategy for developing many functional materials and systems. In this work, it is demonstrated that 4-octyloxy-4'-cyanobiphenyl (8OCB) liquid crystals can be patterned into well-oriented stripes with very high micrometer-scale precision using a sandwich system through a dewetting method. The preparation temperature, concentration, and surface energy are combined to control the morphology and orientation of 8OCB microstripe arrays assisted by silicon micropillars. Microstripes prepared below the isotropic temperature were uniform, well-ordered, and showed high electricity. In addition, 8OCB molecules have a strong tendency toward antiparallel alignment, nearly standing up on the substrate with long axes parallel to the microstripe. Also, we point out the mechanism for the self-assembly process of 8OCB on the air-liquid and liquid-solid surface.

A novel cost-effective methodology for the screening of nanocellulose producing micro-organisms.

In this paper, the work has been done to develop a cost-effective methodology, for the isolation of the potential producer of bacterial nanocellulose. No report is available in the literature, on the use of gram flour and table sugar for the screening of nanocellulose-producing isolates. Since commercially used, Hestrin-Schramm medium is expensive for the isolation of nanocellulose-producing micro-organisms, the possibility of using gram flour-table sugar medium was investigated in this work. Qualitative screening of micro-organisms was done using cost-effective medium, i.e., gram flour-table sugar medium. Qualitative analysis of various nanocellulose-producing bacteria depicted that cellulose layer production occurred on both HS medium and gram flour-table sugar medium. The yield of nanocellulose was also better on air-liquid surface in case of gram flour-table sugar medium as compared to HS medium. 16S rRNA was used for molecular characterization of bacterial strain and the best nanocellulose producer was identified as Novacetimonas hansenii BMK-3_NC240423 (isolated from rotten banana). FTIR and FE-SEM studies of nanocellulose pellicle produced on HS medium and gram flour-table sugar medium demonstrated equivalent structural, morphological, and chemical properties. The cost of newly designed medium (0.01967$/L) is nearly 90 times lower than the Hestrin-Schramm medium (1.748$/L), which makes the screening of nanocellulose producers very cost-effective. A strategy of using gram flour extract-table sugar medium for the screening of nanocellulose-producing micro-organisms is a novel approach, which will drastically reduce the screening associated cost of cellulose-producing micro-organisms and also motivate the researchers/industries for comprehensive screening programme for getting high cellulose-producing microbes.

An experimental and modeling approach to describe the deactivation of cellulases at the air-liquid interface.

Understanding the reaction mechanisms involved in the enzymatic hydrolysis of cellulose is important because it is kinetically the most limiting step of the bioethanol production process. The present work focuses on the enzymatic deactivation at the air-liquid interface, which is one of the aspects contributing to this global deactivation. This phenomenon has already been experimentally proven, but this is the first time that a model has been proposed to describe it. Experiments were performed by incubating Celluclast cocktail solutions on an orbital stirring system at different enzyme concentrations and different surface-to-volume ratios. A 5-day follow-up was carried out by measuring the global FPase activity of cellulases for each condition tested. The activity loss was proven to depend on both the air-liquid surface area and the enzyme concentration. Both observations suggest that the loss of activity takes place at the air-liquid surface, the total amount of enzymes varying with volume or enzyme concentration. Furthermore, tests performed using five individual enzymes purified from aTrichoderma reesei cocktail showed that the only cellulase that is deactivated at the air-liquid interface is cellobiohydrolaseII. From the experimental data collected by varying the initial enzyme concentration and the ratio surface to volume, it was possible to develop, for the first time, a model that describes the loss of activity at the air-liquid interface for this configuration.

GCN5L1 regulates pulmonary surfactant production by modulating lamellar body biogenesis and trafficking in mouse alveolar epithelial cells

BackgroundThe pulmonary surfactant that lines the air–liquid surface within alveoli is a protein–lipid mixture essential for gas exchange. Surfactant lipids and proteins are synthesized and stored in the lamellar body (LB) before being secreted from alveolar type II (AT2) cells. The molecular and cellular mechanisms that regulate these processes are incompletely understood. We previously identified an essential role of general control of amino acid synthesis 5 like 1 (GCN5L1) and the biogenesis of lysosome-related organelle complex 1 subunit 1 (BLOS1) in surfactant system development in zebrafish. Here, we explored the role of GCN5L1 in pulmonary surfactant regulation.MethodGCN5L1 knockout cell lines were generated with the CRISPR/Cas9 system. Cell viability was analyzed by MTT assay. Released surfactant proteins were measured by ELISA. Released surfactant lipids were measured based on coupled enzymatic reactions. Gene overexpression was mediated through lentivirus. The RNA levels were detected through RNA-sequencing (RNA-seq) and quantitative reverse transcription (qRT)- polymerase chain reaction (PCR). The protein levels were detected through western blotting. The cellular localization was analyzed by immunofluorescence. Morphology of the lamellar body was analyzed through transmission electron microscopy (TEM), Lysotracker staining, and BODIPY phosphatidylcholine labeling.ResultsKnocking out GCN5L1 in MLE-12 significantly decreased the release of surfactant proteins and lipids. We detected the downregulation of some surfactant-related genes and misregulation of the ROS–Erk–Foxo1–Cebpα axis in mutant cells. Modulating the activity of the axis or reconstructing the mitochondrial expression of GCN5L1 could partially restore the expression of these surfactant-related genes. We further showed that MLE-12 cells contained many LB-like organelles that were lipid enriched and positive for multiple LB markers. These organelles were smaller in size and accumulated in the absence of GCN5L1, indicating both biogenesis and trafficking defects. Accumulated endogenous surfactant protein (SP)-B or exogenously expressed SP-B/SP-C in adenosine triphosphate-binding cassette transporterA3 (ABCA3)-positive organelles was detected in mutant cells. GCN5L1 localized to the mitochondria and LBs. Reconstruction of mitochondrial GCN5L1 expression rescued the organelle morphology but failed to restore the trafficking defect and surfactant release, indicating specific roles associated with different subcellular localizations.ConclusionsIn summary, our study identified GCN5L1 as a new regulator of pulmonary surfactant that plays a role in the biogenesis and positioning/trafficking of surfactant-containing LBs.

Generating Functional Multicellular Organoids from Human Placenta Villi.

The interaction between trophoblasts, stroma cells, and immune cells at the maternal-fetal interface constitutes the functional units of the placenta, which is crucial for successful pregnancy outcomes. However, the investigation of this intricate interplay is restricted due to the absence of efficient experimental models. To address this challenge, a robust, reliable methodology for generating placenta villi organoids (PVOs) from early, late, or diseased pregnancies using air-liquid surface culture is developed. PVOs contain cytotrophoblasts that can self-renew and differentiate directly, along with stromal elements that retain native immune cells. Analysis of scRNA sequencing and WES data reveals that PVOs faithfully recapitulate the cellular components and genetic alterations of the corresponding source tissue. Additionally, PVOs derived from patients with preeclampsia exhibit specific pathological features such as inflammation, antiangiogenic imbalance, and decreased syncytin expression. The PVO-based propagation of primary placenta villi should enable a deeper investigation of placenta development and exploration of the underlying pathogenesis and therapeutics of placenta-originated diseases.

Computational fluid dynamics and machine learning algorithms analysis of striking particle velocity magnitude, particle diameter, and impact time inside an acinar region of the human lung

Complementing computational fluid dynamics (CFD) simulations with machine learning algorithms is becoming increasingly popular as the combination reduces the computational time of the CFD simulations required for classifying, predicting, or optimizing the impact of geometrical and physical variables of a specific study. The main target of drug delivery studies is indicating the optimum particle diameter for targeting particular locations in the lung to achieve a desired therapeutic effect. In addition, the main goal of molecular dynamics studies is to investigate particle–lung interaction through given particle properties. Therefore, this study combines the two by numerically determining the optimum particle diameter required to obtain an ideal striking velocity magnitude (velocity at the time of striking the alveoli, i.e., deposition by sedimentation/diffusion) and impact time (time from release until deposition) inside an acinar part of the lung. At first, the striking velocity magnitudes and time for impact (two independent properties) of three different particle diameters (0.5, 1.5, and 5 μm) are computed using CFD simulations. Then, machine learning classifiers determine the particle diameter corresponding to these two independent properties. In this study, two cases are compared: A healthy acinus where a surfactant layer covers the inner surface of the alveoli providing low air–liquid surface tension values (10 mN/m), and a diseased acinus where only a water layer covers the surface causing high surface tension values (70 mN/m). In this study, the airflow velocity throughout the breathing cycle corresponds to a person with a respiratory rate of 13 breaths per minute and a volume flow rate of 6 l/min. Accurate machine learning results showed that all three particle diameters attain larger velocities and smaller impact times in a diseased acinus compared to a healthy one. In both cases, the 0.5-μm particles acquire the smallest velocities and longest impact times, while the 1.5-μm particles possess the largest velocities and shortest impact times.

Hybrid (Bovine Serum Albumin)/Poly(N-vinyl-2-pyrrolidone-co-acrylic acid)-Shelled Microbubbles as Advanced Ultrasound Contrast Agents.

Microbubbles are routinely used ultrasound contrast agents in the clinic. While a soft protein shell is commercially preferable for imaging purposes, a rigid polymer shell demonstrates prolonged agent stability. Hence, combining polymers and proteins in one shell composition can advance microbubble properties. We formulated the hybrid "protein-copolymer" microbubble shell with a complex of bovine serum albumin and an amphiphilic copolymer of N-vinyl-2-pyrrolidone and acrylic acid. The resulting microbubbles demonstrated advanced physicochemical and acoustic properties, preserving in vitro biocompatibility. Adjusting the mass ratio between protein and copolymer allowed fine tuning of the microbubble properties of concentration (by two orders, up to 1010 MBs/mL), mean size (from 0.8 to 5 μm), and shell thickness (from 28 to 50 nm). In addition, the minimum air-liquid surface tension for the "protein-copolymer" solution enabled the highest bubble concentration. At the same time, a higher copolymer amount in the bubble shell increased the bubble size and tuned duration and intensity of the contrast during an ultrasound procedure. Demonstrated results exemplify the potential of the hybrid "protein-polymer" microbubble shell, allowing tailoring of microbubble properties for image-guided applications, combining advances of each material involved in the formulation.

Simultaneous Solar Steam and Electricity Generation from Synergistic Salinity‐Temperature Gradient

AbstractSolar‐driven interfacial evaporation by localization of solar heating at the air–liquid surface has emerged as a cost‐effective desalination technology. The rapid interfacial evaporation induces simultaneous salinity and temperature gradient between evaporation surface and bulk water, which enables electricity generation but is not comprehensively utilized. Herein, the combination of a thermogalvanic cell (TGC) and reverse electrodialysis (RED) in solar‐driven interfacial evaporation is proposed to extract energy from temperature and salinity gradients simultaneously. Because of the synergistic ion transport effect, the coupling of TGC and RED enables mutual power enhancement by orders of magnitude based on the rational spatial layout and the fabrication of composite electrodes. Finally, a steam‐electricity cogeneration system is designed, which achieves the 1.4 kg m−2 h−1 vapor and 1.11 W m−2 electricity simultaneously under one sun illumination. This concept opens a promising avenue towards a solar‐driven water‐energy nexus.

The Effects of Solvent on Doctor‐Bladed Perovskite Light Absorber under Ambient Process Condition for Multiple‐Cation Mixed Halide Perovskites

A doctor‐blading process for the fabrication of triple‐cation halide‐perovskite thin films using eco‐friendly solvents under ambient conditions is demonstrated. An eco‐friendly perovskite precursor composed of γ‐butyrolactone (GBL)/dimethylsulfoxide (DMSO)/isopropanol (IPA) mixture is used. The coordination between PbI2 and DMSO effectively suppresses the perovskite crystal grow rate which results in a dense and uniform film. However, the intermediate DMSO–PbI2 phase residual has a negative impact on the perovskite film quality. The amount of residues, the trap‐state defect density, the perovskite film uniformity, and the device performance can be considerably affected by adding IPA in the precursor due to its capability to facilitate DMSO evaporation. Heating post‐treatment on the top side of the film homogenizes the evaporation rate of the air–liquid surface which leads to a larger grain size and unbroken film. The device using perovskite solution with GBL/DMSO/IPA mixture as solvent achieves a decent power conversion efficiency (PCE) of 12.3% with a Voc of 1.01 V and a Jsc of 19.3 mA cm−2. The bare device retains 76.5% of its original PCE after 25 days under ambient environment at 35 °C, with 35–40% relative humidity. A large‐size device with an active area of 2.4 cm2 delivers a PCE of 8.52%.

Effects of air-side freestream turbulence on the development of air–liquid surface waves

It is important to investigate the effects of air-side freestream turbulence on the development of air–liquid surface waves. Two turbulent-grid air flows are generated by regular and fractal grids in a wind-wave tank. Wind velocity and water-level fluctuations are measured with and without grids. The results show that regular and fractal grids can generate turbulent-grid air flows with different wind velocity fluctuations. The spectra of water-level fluctuations in the regular-type and fractal-type grid cases are consistent with those of pure wind-driven waves without a grid. Furthermore, as wind-wave properties, including the fetch law, dispersion relation, and Toba’s 3/2 power law, all hold in cases with and without grids, it is confirmed that the waves develop through the turbulence only near the free water surface, and not through the air-side freestream turbulence. This suggests that the effects of air-side freestream turbulence on wave development are negligible.

Surface rheology and morphology of beer protein and iso-humulone at air-liquid surface

Foam is one of the unique properties of beer, but how the amphiphilic components stabilize the foam is still not fully understood. This study concerns the main surface active components. For this purpose, protein from barley and iso-humulone from hop, were extracted from raw materials separately to be able to consider their effect separately and in the controlled mixture. The layers were formed in three ways, i.e. single component, pre-mixed solution and sequential addition of the individual components. Drop tensiometry and Brewster angle microscopy were employed to reveal the surface tension effects, rheological properties and morphology of the adsorbed layers.Both protein and iso-humulone showed surface activity and the combination gave synergistic effects in terms increasing the surface pressure. Surface rheology showed the combination of pre-mixed solutions of protein and iso-humulone formed the stiffest surface film. The pre-mixed solution gave higher dilatational moduli than if the two components were added sequentially. Furthermore, protein had a major influence on resisting deformation of the surface layer. The attractive interaction was confirmed by comparing the surface rheology and morphology of adsorbed layers formed by pre-mixed solutions and sequential addition. Iso-humulone also had a significant influence on interfacial properties. But this depends on whether it was pre-mixed with protein before added in to a buffer sub-phase or added to a pre-adsorbed protein layer. BAM reveals different surface morphology between the sequential addition and the pre-mixed sample. Thus, the property of the adsorbed film depends not only on the chemical composition, but also on the addition order of components.

Antibacterial and antiadherence properties of the leaves of <i>Ficus thoninngii</i> blume on <i>Acinetobacter baumannii</i>

Background: The ability of Acinetobacter baumannii to adhere and persist in any environment has aided its persistence in hospital environments. Ficus thonningii Blume has antimicrobial abilities and may halt the attachment of microorganisms to air-liquid surfaces.Objective: To investigate the antibacterial and antiadherence properties of the leaves of Ficus thonningii on A. baumannii.Materials and Methods: Antibiogram of twenty-three clinical isolates of A. baumannii including a typed strain was determined using disc-diffusion method. Antimicrobial activities of the leaf extracts and fractions of Ficus thonningii were screened by agar-well diffusion. The minimum inhibitory concentration (MIC) was determined by agar-dilution. The ability of the organism to adhere to air-liquid surface and form pellicle, and the ability of the extracts to inhibit the pellicles formed were investigated. Pellicle forming strains of E. coli ATCC 35218 and A. baumannii 111A were used as controls. One-way ANOVA was used to compare the optical densities of the pellicles formed.Results: At 50 mg/mL, the inhibition zone diameter produced by ethyl acetate, methanol and n-hexane extracts ranged from 0-15 mm with ethyl acetate extract having the highest activity. The MIC ranged from 0.039-1.25 mg/mL, 0.039-20 mg/mL and 1.25-20 mg/mL for ethyl acetate, methanol and hexane extracts respectively while the MBC ranged from 5-20 mg/mL, 1.25-20 mg/ml and ≥20 mg/mL also respectively. Pellicle formation was observed in 62.0 % of the bacterial isolates. There was a slight reduction in the pellicles formed at 12.5 mg/mL concentration of the extracts.Conclusions: The study has shown that Ficus thonningii can be used in the management and treatment of infections caused by A. baumannii. It also has the ability to inhibit pellicles formed by the organism at increased concentrations.Keywords: Acinetobacter baumannii, Ficus thonningii, Antibacterial, Antiadherence, Pellicle

Efficient accumulation of sclerotiorin via overcoming low pH caused by overflow carbon metabolism during cell suspension culture of Penicillium sclerotiorum

Abstract Sclerotiorin is the secondary metabolite of Penicillium sclerotiorum, which is usually produced by solid state fermentation or liquid culture without stirring (formation of mycelial mat on air-liquid surface). In the present work, it was confirmed that malic acid was produced during cell suspension culture in a liquid medium (mycelia acting as planktonic cells) using resting cells as whole cell biocatalyst. The accumulation of malic acid was caused by overflow carbon metabolism at high glucose concentration (Crabtree effect), which led to low ambient pH value. The low ambient pH repressed sclerotiorin biosynthesis. In order to overcome the low pH caused by Crabtree effect, many influenced factors, such as phosphate buffer system, initial pH, biomass loading, slowly metabolized carbon resource, and mixed sugars as carbon resource, were investigated. Finally, the low pH caused by Crabtree effect was eliminated by taking the advantage of carbon metabolite repression via utilization of mixed sugars (glucose and lactose) as carbon resource. And then, an ideal pH approximately 3.8 was maintained and corresponding high concentration of sclerotiorin (150 absorbance unit at 365 nm, corresponding to 1.9 g/l) was achieved by cell suspension culture with a relatively high biomass loading 11.7 g/l DCW (dry cell weight).

Submerged culture of marine-derived Penicillium sclerotiorum FS50 to produce sclerotiorin

Abstract Production of secondary metabolites by filamentous fungi, such as sclerotiorin from Penicillium sclerotiorum, sometimes is limited to solid state fermentation or submerged culture without stirring (mycelial mat on air-liquid surface). In the present work, sclerotiorin was isolated and identified by submerged culture of the marine-derived P. sclerotiorum FS50 in Czapek medium without stirring while no sclerotiorin observed by submerged culture with stirring under the same condition. It was found that low pH (below 6 via adjustment of nitrogen and phosphorus concentration in the Czapek medium) led to sclerotiorin accumulation by submerged culture with stirring (mycelia acting as planktonic cells). Replacement of NaNO3 in the Czapek medium with NH4Cl further confirmed that maintaining pH 4–6 was key to accumulation of sclerotiorin by submerged culture with stirring.

Effect of fish gelatine-sodium alginate interactions on foam formation and stability

The effect of fish gelatine (FG)−alginate (AL) interactions on the formation and stability of foams was investigated by examining relationships between surface, bulk, and foaming properties of aqueous mixtures of FG and AL at 25 °C under different values of pH and FG:AL ratio. Replacing a portion of FG with AL (FG:AL ratio = 80:20, 50:50, and 20:80) at pH 5.0 or 7.0 increased the air-liquid surface tension, negative electrophoretic mobility, bulk viscosity, and particle size of FG−AL mixtures. At pH 3.5 (below the isoelectric point of FG), the AL replacement increased the particle size more dramatically; however, it suppressed trends of increasing negative electrophoretic mobility and bulk viscosity, and even reduced the surface tension, due to stronger electrostatic attractions between oppositely charged FG and AL molecules and the resulting formation of more charge-neutralised FG−AL complexes. Foaming ability became stronger as the surface tension decreased, the negative electrophoretic mobility approached to zero (more charge-neutralised), and the bulk viscosity decreased; however, it was not closely correlated with particle size. FG−AL mixtures had a weaker foaming ability than solutions prepared only with FG or whey protein concentrate; however, these mixtures exhibited much higher foam stability during storage at 25 °C. FG−AL mixtures prepared at pH 3.5 and a FG:AL ratio of 80:20 showed the best foaming ability and foam stability.

Impingement of Triton X-100 solution drops on paraffin film–Relaxation of surface dilational rate

The impact dynamics of a solution drop of Triton X-100 impinging on a paraffin film was studied, specifically to develop a new method for evaluating the in situ surface dilational rate, λ. The drop images (side and top views) during the impingement process were sequentially digitized and used to calculate the interfacial areas of the liquid-air and liquid-solid interfaces. The data of interfacial area were then used to calculate the relaxation of λ. The surface dilational rate showed a strong oscillation at the beginning of the drop impact. It oscillated from 0 down to −390/s, up to 290/s, and then down to −200/s. This surface dilational rate is far above 2.4/s, which is the lower limit of λ for an expanding pendant bubble in a Triton X-100 solution with an isolated air-liquid surface (Lin et al., 2017). A simple but useful theoretical framework is given for the calculation of the dynamic surface dilational rate, surface concentration and surface tension of an impinging drop of surfactant solution.

Finite-Size and Solvent Dependent Line Tension Effects for Nanoparticles at the Air-Liquid Surface.

The line tension for a nanoparticle (NP) at the air-liquid surface can be determined by examining the variation in NP solution surface tension with bulk NP concentration. In this publication the variation in line tension with liquid solvent is examined for the homologous series of liquids from n-decane through to n-octadecane. Finite-size line tension effects are also studied by examining the variation in line tension with NP size for NPs at the air-octadecane surface. Both the line tension variation with solvent and NP size can be qualitatively explained using an interface displacement model for the line tension.

Effect of cation alkyl chain length on surface forces and physical properties in deep eutectic solvents

Deep eutectic solvents (DESs) have been prepared from mixtures of alkyl ammonium bromide salts (ethylammonium bromide, propylammonium bromide and butylammonium bromide) and glycerol at a 1: 2 M ratio. These DESs reveal the effect of cation alkyl chain length on interfacial structure at mica (a model anionic) surface. As the cation chain length is increased it becomes more amphiphilic and solvophobic, leading to stronger association of alkyl chains, as revealed by atomic force microscope force curve measurements. The effect of increasing cation alkyl chain length on phase transition and thermal decomposition temperatures, density, refractive index, viscosity, ionic and thermal conductivity and air liquid surface tension are also probed. Combined, these studies reveal the length of the cation alkyl chain weakly affects composition dependent properties (e.g. density, refractive index, thermal conduction, etc.) but has a stronger effect where intermolecular (ionic) forces play a role, such as on viscosity, and on surface tension and interfacial structure. To the authors knowledge, this is the first report of amphiphilic nanostructure in DESs and the first systematic study of the effect of cation alkyl chain length on physical properties.

Synthesis and Surface Active Properties of a Gemini Imidazoline Amphoteric Surfactant

AbstractThe gemini imidazoline amphoteric surfactant was prepared in two steps. We first reacted lauric acid and triethylenetetramine to obtain the intermediate called bisalkyl‐bis‐imidazoline. We analyzed it by 1H NMR, and the yield was 82.45 % according to perchloric acid non‐aqueous titration. The intermediate was then quaternized using sodium 2‐chloroethanesulfonic acid in a mixture of isopropyl alcohol and water, during which we controlled the pH between 8 and 9 and the temperature between 80 and 90 °C to prepare C12‐bis‐imi. The air–liquid surface tension was measured by a tensiometer at 298 ± 0.1 K. The results show that the critical micelle concentration (CMC) was 2.25 × 10−3 mol/L and the surface tension at the CMC (γCMC) was 30.42 mN/m. C12‐bis‐imi showed a synergistic effect in combination with lauric alcohol with nine ethylene oxide groups (AEO9). The synergistic effect is most striking when the mole ratio of C12‐bis‐imi/AEO9 was 1/1, and the corresponding CMC was 9.79 × 10−5 mol/L and the γCMC was 37.61 mN/m.

Surface tension and 0.1 MPa density of 1-alkyl-3-methylimidazolium tetrafluoroborates in a homologous series perspective

Experimental data over the temperature range from (263 to 365)K are presented on the 0.1MPa density and air–liquid surface tension for 1-Cn-3-methylimidazolium tetrafluoroborates with n=3,5,7,9,10 and 12, still poorly or even not studied in these respects at all. The reported density data were obtained using a single-sinker buoyancy method with an estimated combined expanded uncertainty at 0.95 confidence level Uc not exceeding 0.6kg·m−3 (6·10-4ϱ). The surface tension data were obtained by the Wilhelmy plate method with Uc from 0.04 to 0.12mN·m−1 for n=3 and n=12, respectively, and by du Noüy ring method with Uc from 0.17 to 0.8mN·m−1. The Krűss K100 Mk2 tensiometer was used to determine the buoyancy and surface tension forces. The new data allowed to identify the most credible density and surface tension values for 1-Cn-3-methylimidazolium tetrafluoroborates with n=2,4,6, and 8. Empirical models rooted in group contribution and parachor concept are reported, generating recommended values for the 0.1MPa density and the surface tension for members of the studied homologous series. The worst-case error of the recommended values of the density and surface tension are estimated to 0.1% and 0.3mN·m−1, respectively.