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The interaction behavior and the process of mixed micellization for binary mixtures of an amino sulfonate amphoteric surfactant sodium 3-(N-dodecyl ethylenediamino)-2-hydropropyl sulfonate (C12AS) and a cationic surfactant octadecyltrimethylammonium bromide (OTAB) in aqueous solution of NaCl (0.250 M) at 313.15 K were investigated using both the tensiometry and the UV–vis spectrometry using pyrene as a probe. The mixed critical micelle concentration (cmc) of the C12AS/OTAB mixtures were determined by two techniques. Based on regular solution theory, pseudophase separation model, Clint’s model, Rosen’s model, and Rubingh’s model, some parameters (including the ideal mixed cmc, the compositions in mixed micelle, the interaction parameters between two surfactants, the activity coefficients in mixed micelle, some thermodynamic parameters, etc.) were evaluated and calculated. The deviation of mixed cmc from its ideal value indicates a nonideal mixing between two surfactants. In comparison with those in aqueous solutions, the presence of NaCl induces some differences in the dependence of compositions in mixed micelle on its content in bulk solution, and there has a stronger synergism between two surfactants. Thermodynamic parameters shows that the mixed micellization of the C12AS/OTAB mixtures is an entropically spontaneous process, while the addition of NaCl to the solution can partly suppress the contribution of entropy to the process of micellization. The electrostatic attraction between two surfactants, the steric effect of hydrophilic group of C12AS, and the interaction repulsion between head groups of individual surfactants may play vital roles on the process of micellization. These findings help with probing the effect of additives on the process of micellization and understanding the interaction behavior between surfactants so as to design surfactant formulations.

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Wireless sensor networks (WSNs) are adopted in a variety of fields where coverage enhancing is a critical challenge because of the requirements of service quality, cost, and energy consumption. Coverage-enhancing approaches have currently attracted a lot of interest owing to their superior abilities in the deployment of the WSNs, e.g., maximum coverage, minimum sensors, and minimum energy. In this paper, a differential evolution-based regional coverage-enhancing algorithm is proposed for directional 3D WSNs, which is able to maximizing coverage while minimize the number of sensors. First, a directional cone perception model is designed to better display the actual sensing performance of sensor nodes. Subsequently, the coverage region is established to describe the perceptual range of nodes. Thereafter, a three-stage coverage-enhancing method is derived, which includes the pitch angle optimization, the deflection angle optimization and the redundant node sleeping. These strategies are designed to maximize the perception range of a single sensor node, maximize the coverage rate, and minimize the number of nodes, respectively. Finally, simulation results show that our method is able to ensure better performance compared to the stateof-the-art frameworks.

With the advancement of multimedia technology, a series of problems have emerged in the reform of college English teaching. How to use multimedia to assist college students in English learning has become a meaningful study. Multimedia-assisted instruction is a common method of teaching English. The design of multimedia-assisted English teaching resource software determines its development, management, evaluation and other aspects, so the design of multimedia platform plays a vital role in the effect of multimedia teaching. This paper will discuss the design and implementation of multimedia-assisted college English independent education resources from the perspective of knowledge classification. Through the content analysis, some problems exist in the design process of some college English multimedia teaching, and the status quo is analyzed. It also studies the difficulties of college students in the process of multimedia assisted learning, and how college students hope to design multimedia independent learning multimedia platform. Finally, the five knowledge classification learning theories of “listening, speaking, reading, writing and translating” can change the status quo, meet the needs of college students, and develop the knowledge of vocabulary, grammar and listening in college English. The design strategy of self-learning multimedia-assisted instruction and the design of college English self-learning multimedia teaching is briefly written.

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