JCIS open最新文献

The qualitative presentation from Winsor on an interfacial balance of interactions between the surfactant and the oil and water phases has been transformed into a multivariable linear equation so-called hydrophilic-lipophilic deviation (HLD). This relation involves at least 6 independent variables (surfactant head and tail specifications, water salinity, oil nature, temperature, and pressure) with a MacLaurin series first order approximation, i.e., a linear multivariable expression. After 40 years of practical experience, it can be said that the HLD relation matches well the experimental data, with only very few exceptions with complex mixtures. Herein, we clear the confusion concerning the meaning and the mathematical handling of the surfactant parameter in the HLD equation. We start with a presentation of simple surfactant systems with only 4 parameters (water salinity, oil nature, surfactant nature, and temperature) as was done 40 years ago. Later, we present a critical discussion on the surfactant term, concerning binary surfactant systems, and on strategies for applications in ternary surfactant mixtures. We have found that the surfactant parameters can only be compared in a series of surfactants with the same head group, where the surfactant parameter is a linear function of the surfactant tail length.

A simple eco-friendly method was employed to generate white light using pomegranate-PVA - curcumin mediated silver nanoparticles (CAg NP-PVA) mixture. The white light emission is obtained by integrating the green emitting curcumin and blue emitting pomegranate extract. Controlling the emission of curcumin with Ag NP-PVA and mixing with pomegranate extract resulted in efficient white light with the Commission Internationale d’Eclairage (CIE) chromaticity coordinate (0.28,0.31). Ag NP-PVA and anthocyanin played a significant role in obtaining CIE coordinate close to that of pure white light (0.33,0.33). The optimized white light emission obtained from pomegranate- CAg NP-PVA mixture is cheap and fairly green in nature.

Highly functional and also highly porous materials are presenting great advantages for applications in energy storage, catalysis and separation processes, which is why a continuous development of new materials can be seen. To create a material combining the promising potential interactions of triazine groups with the electrostatic or hydrogen bonding interactions of phenolic groups, a completely new polymeric resin was synthesized. From an eco-friendly dispersion polymerization in water, a copolymer network was obtained, which includes nine hydroxyl groups and one s-triazine ring per repetition unit. The polymer forms highly porous particles with specific surface areas up to 531 ​m²/g and a negative streaming potential over a great pH range. The adsorption isotherms of Ni²⁺, Cd²⁺, and Pb²⁺ were studied in more detail achieving very good adsorption capacities (16 mg Ni²⁺/g, 24 mg Cd²⁺/g, and 90 mg Pb²⁺/g). Demonstrating excellent properties for adsorption applications. The adsorbent exhibited selectivity for the adsorption of Pb²⁺ over more commonly occurring but non-toxic metal ions such as Fe²⁺, Ca²⁺, Mg²⁺, and K⁺. Furthermore, reusability of the material was demonstrated by facile, quantitative desorption of adsorbed Pb²⁺ with a small amount of diluted HCl, circumventing organic chelators. Subsequently, adsorption was carried out without decrease in adsorption performance.

Colloids that are able to navigate via predefined paths and adapt to complex environments hold great promises as miniaturized machines and model systems for active soft matter research. Here, we design an intelligent system that integrates dynamic magnetic field and light control with in-situ determination of particle position and velocity via Matlab-based image acquisition and analysis. We apply the system to realize programmable and feedback control over the motion of a magnetic and photoactive colloid. Specifically, we direct the active colloid into pentagram-like navigation, circular motion of various size, and spiral-like motion by changing the travelling direction, discretely or continuously, the self-propelled velocity, and a combination of the two, enabled by dynamic change of magnetic field, light intensity and both. Moreover, we demonstrate the ability of the system for on-the-fly self-correction to follow predefined path with high fidelity, and adaptability to complex surroundings with definable birdlike vision based on in-situ processing of information. We expect the programmability and adaptability of magnetic and photoactive colloids enabled by multiple handles, magnetic field and light, open up new opportunities for active soft matter research, including intelligent microrobotics, collective nonequilibrium dynamics and novel photonic fluids.

Hypothesis

The large-scale implementation of hydrogen economy requires immense storage spaces to facilitate the periodic storage/production cycles. Extensive modelling of hydrogen transport in porous media is required to comprehend the hydrogen-induced complexities prior to storage to avoid energy loss. Wettability of hydrogen-brine-rock systems influence flow properties (e.g. capillary pressure and relative permeability curves) and the residual saturations, which are all essential for subsurface hydrogen systems.

Model

This study aims to understand which parameters critically control the contact angle for hydrogen-brine-rock systems using the surface force analysis following the DLVO theory and sensitivity analysis. Furthermore, the effect of roughness is studied using the Cassie-Baxter model.

Findings

Our results reveal no considerable difference between H₂ and other gases such as N₂. Besides, the inclusion of roughness highly affects the observed apparent contact angles, and even lead to water-repelling features. It was observed that contact angle does not vary significantly with variations of surface charge and density at high salinity, which is representative for reservoir conditions. Based on the analysis, it is speculated that the influence of roughness on contact angle becomes significant at low water saturation (i.e. high capillary pressure).

Biosurfactants are widely used in many industrial settings ranging from cosmetic to petroleum industries. Among various biosurfactants available in the market, rhamnolipid is a well-known bacterial biosurfactant produced by the Pseudomonas aeruginosa bacteria. However, despite its wide applications, no detailed and systematic study is available on the rheological characterization of this biosurfactant solution, which is an essential property to investigate for many practical applications. Therefore, this study aims to present a thorough and complete investigation of this biosurfactant's shear and extensional rheological behaviours. While steady shear and small amplitude oscillatory shear (SAOS) measurements were conducted to investigate the shear rheological behaviour, the dripping-onto-substrate (DoS) extensional rheometry technique was used to understand its extensional rheological behaviour. A chemically derived surfactant (cetyltrimethyl ammonium bromide (CTAB)) was also used in our analysis to show and discuss the qualitative and quantitative differences in their rheological behaviours. Along with the detailed rheological study, some studies on the physicochemical properties, such as surface tension, contact angle, particle size analysis, thermal stability, etc., were also conducted to make an overall comparison between the two surfactants. Both surfactants show strong shear-thinning and extensional hardening behaviors in shear and extensional rheological flows, respectively. However, the zero-shear rate viscosity and extensional viscosity are found to be larger for rhamnolipid surfactant solutions than for CTAB. The corresponding shear and extensional relaxation times also follow the same trend. Furthermore, the surface tension is found to be less, and the contact angle is found to be more for rhamnolipid biosurfactant than that for CTAB. Rhamnolipid shows more excellent thermal stability, particularly at high temperatures than CTAB. Therefore, the results and discussion presented in this study will help to choose the present rhamnolipid biosurfactant for any particular application, particularly where the knowledge of the rheological responses of a surfactant solution is essential.

The physical phenomena of nanofluid at high temperature motivate us to analyze problems with temperature-reliant fluid properties, like viscosity and thermal conductivity. Since in glass blowing, viscosity and thermal conductivity of the fluid may gets affected in such high temperature. This communication deals with the unsteady flow of nanofluid generated by nonlinear expansion of the surface. Temperature-dependent fluid viscosity and thermal conductivity are considered in the investigation of the problem. The flow of nanofluid is modeled using famous the Buongiorno's two-phase model, which includes the simultaneous effect of Brownian motion and thermophoresis diffusion. Appropriate transformations are adopted to obtain the ODEs from governing PDEs. Then MATLAB ‘bvp4c’ computation is used to solve the problem and to get a clear insight of the influences of various parameters. Graphical comparisons are made to check the accuracy of used numerical method. The study explores that heat transfer rate significantly enhances by the index of nonlinearity, variable viscosity and thermal conductivity parameters. Unsteadiness of the flow can be used as a controlling parameter to reduce the surface drag, heat and nano-mass transfer rate. Variable viscosity parameter leads to enhance the velocity near the surface and reducing the concentration of the nanoparticles. The thermal and concentration boundary layer thickens with thermal conductivity parameters. Nanofluid temperature and concentration of nanoparticles decay with nonlinear expanding index.