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Advances in Colloid and Interface Science (v.169, #2)
Green synthesis of biogenic metal nanoparticles by terrestrial and aquatic phototrophic and heterotrophic eukaryotes and biocompatible agents by Kannan Badri Narayanan; Natarajan Sakthivel (pp. 59-79).
The size, shape and controlled dispersity of nanoparticles play a vital role in determining the physical, chemical, optical and electronic properties attributing its applications in environmental, biotechnological and biomedical fields. Various physical and chemical processes have been exploited in the synthesis of several inorganic metal nanoparticles by wet and dry approaches viz., ultraviolet irradiation, aerosol technologies, lithography, laser ablation, ultrasonic fields, and photochemical reduction techniques. However, these methodologies remain expensive and involve the use of hazardous chemicals. Therefore, there is a growing concern for the development of alternative environment friendly and sustainable methods. Increasing awareness towards green chemistry and biological processes has led to a necessity to develop simple, cost-effective and eco-friendly procedures. Phototrophic eukaryotes such as plants, algae, and diatoms and heterotrophic human cell lines and some biocompatible agents have been reported to synthesize greener nanoparticles like cobalt, copper, silver, gold, bimetallic alloys, silica, palladium, platinum, iridium, magnetite and quantum dots. Owing to the diversity and sustainability, the use of phototrophic and heterotrophic eukaryotes and biocompatible agents for the synthesis of nanomaterials is yet to be fully explored. This review describes the recent advancements in the green synthesis and applications of metal nanoparticles by plants, aquatic autotrophs, human cell lines, biocompatible agents and biomolecules.Display Omitted► Nanoparticles synthesized using biological processes are gaining merit. ► Biological synthesis is inexpensive and uses non-hazardous chemicals. ► Use of phototrophic eukaryotes and biocompatible agents is eco-friendly. ► Greener nanoparticles are used in biomedical applications.
Keywords: Nanotechnology; Eukaryotes; Phototrophs; Nanoparticles; Plants; Algae; Diatoms; Human cell lines; Biocompatible
Mimicking natural superhydrophobic surfaces and grasping the wetting process: A review on recent progress in preparing superhydrophobic surfaces by Y.Y. Yan; N. Gao; W. Barthlott (pp. 80-105).
A typical superhydrophobic (ultrahydrophobic) surface can repel water droplets from wetting itself, and the contact angle of a water droplet resting on a superhydrophobic surface is greater than 150°, which means extremely low wettability is achievable on superhydrophobic surfaces. Many superhydrophobic surfaces (both manmade and natural) normally exhibit micro- or nanosized roughness as well as hierarchical structure, which somehow can influence the surface's water repellence. As the research into superhydrophobic surfaces goes deeper and wider, it is becoming more important to both academic fields and industrial applications. In this work, the most recent progress in preparing manmade superhydrophobic surfaces through a variety of methodologies, particularly within the past several years, and the fundamental theories of wetting phenomena related to superhydrophobic surfaces are reviewed. We also discuss the perspective of natural superhydrophobic surfaces utilized as mimicking models. The discussion focuses on how the superhydrophobic property is promoted on solid surfaces and emphasizes the effect of surface roughness and structure in particular. This review aims to enable researchers to perceive the inner principles of wetting phenomena and employ suitable methods for creation and modification of superhydrophobic surfaces.(a) A glycerol drop on Euphorbia myrsinites, which is a robust specimen and well suited to show the surface's repellence against the liquid droplet. (b) The upper side surface of the lotus leaf without the shrinkage artifact. (c) The wax tubules from the upper side of the lotus leaf.Display Omitted► We review the most recent progress in preparing superhydrophobic surfaces. ► The fundamental theories of wetting phenomena are investigated. ► The natural models inspiring to the creation of superhydrophobic surfaces are inspected. ► The main discussion focuses on the formation of surface roughness and structure. ► We present the creation of superhydrophobic surfaces through a variety of techniques.
Keywords: Superhydrophobic surface; Wetting; Lotus effect; Biomimetic; Surface morphology
Heavy Crude Oils/Particle Stabilized Emulsions by Iva Kralova; Sjoblom Johan Sjöblom; Oye Gisle Øye; Sébastien Simon; Brian A. Grimes; Kristofer Paso (pp. 106-127).
Fluid characterization is a key technology for success in process design for crude oil mixtures in the future offshore. In the present article modern methods have been developed and optimized for crude oil applications. The focus is on destabilization processes in w/o emulsions, such as creaming/sedimentation and flocculation/coalescence. In our work, the separation technology was based on improvement of current devices to promote coalescence of the emulsified systems. Stabilizing properties based on particles was given special attention. A variety of particles like silica nanoparticles (AEROSIL®), asphalthenes, wax (paraffin) were used. The behavior of these particles and corresponding emulsion systems was determined by use of modern analytical equipment, such as SARA fractionation, NIR, electro-coalescers (determine critical electric field), Langmuir technique, pedant drop technique, TG-QCM, AFM.Display Omitted► Particle stabilization mechanisms based on indigenous components is described. ► Establishment of techniques for destabilization processes in crude oil emulsions. ► The indigenous components significantly influence the stability of these systems. ► The separation model for poly-disperse emulsions was developed. ► The model was formulated based on first-principle physical mechanisms.
Keywords: Electrocoalescence; Gelation; Naphthenic acids; Particle-stabilized emulsions; Phase diagrams; Separation modeling