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Topic Review
Plastic Waste into Supports for Nanostructured Heterogeneous Catalysts
Plastics are ubiquitous in our society and are used in many industries, such as packaging, electronics, the automotive industry, and medical and health sectors, and plastic waste is among the types of waste of higher environmental concern. The increase in the amount of plastic waste produced daily has increased environmental problems, such as pollution by micro-plastics, contamination of the food chain, biodiversity degradation and economic losses. The selective and efficient conversion of plastic waste for applications in environmental remediation, such as by obtaining composites, is a strategy of the scientific community for the recovery of plastic waste. The development of polymeric supports for efficient, sustainable, and low-cost heterogeneous catalysts for the treatment of organic/inorganic contaminants is highly desirable yet still a great challenge; this will be the main focus of this work. Common commercial polymers, like polystyrene, polypropylene, polyethylene therephthalate, polyethylene and polyvinyl chloride, are addressed herein, as are their main physicochemical properties, such as molecular mass, degree of crystallinity and others. Additionally, we discuss the environmental and health risks of plastic debris and the main recycling technologies as well as their issues and environmental impact. The use of nanomaterials raises concerns about toxicity and reinforces the need to apply supports; this means that the recycling of plastics in this way may tackle two issues. Finally, we dissert about the advances in turning plastic waste into support for nanocatalysts for environmental remediation, mainly metal and metal oxide nanoparticles.
  • 762
  • 18 Jan 2022
Topic Review
Wittig Reactions under Sonication Conditions
Carbonyl olefinations are among the most important organic syntheses that form C=C bonds, as they usually have high yields and in addition offer excellent stereoselectivity. Due to these advantages, carbonyl olefinations have important pharmaceutical and industrial applications. These reactions contain an additional step of an α-functionalized carbanion to an aldehyde or ketone to produce alkenes, but syntheses performed using metal carbene complexes are also known. The Wittig reaction is an example of carbonyl olefination, one of the best ways to synthesize alkenes.
  • 761
  • 28 Jun 2023
Topic Review
Nanocellulose Nanomorphologies
Nanocellulosic materials have attracted special attention because of their performance in different advanced applications, biodegradability, availability, and biocompatibility. Nanocellulosic materials can assume three distinct morphologies, including cellulose nanocrystals (CNC), cellulose nanofibers (CNF), and bacterial cellulose (BC). 
  • 761
  • 17 May 2023
Topic Review
Topical Insulin Delivery
Insulin is one of the cheapest growth factors in the market able to accelerate the re-epithelialization and stimulate angiogenesis and cell migration. However, the effectiveness of topical insulin in wound healing is hampered by the proteases in the wound bed. The encapsulation into nanoparticles improves its stability in the wound, providing adhesion to the mucosal surface and allowing its sustained release. 
  • 761
  • 13 Sep 2021
Topic Review
Adsorption Effect Modification of Lithium–Sulfur Batteries
Lithium–sulfur batteries (LSBs) have high theoretical specific capacity (1675 mAh g−1) and high energy density (2600 Wh kg−1), and the cathode sulfur is low cost, abundant, and environmentally friendly. The “shuttle effect” refers to the phenomenon that Li2Sx (4 ≤ x ≤ 8) produced by the positive electrode diffuses to the negative electrode during the charging and discharging process, and is reduced to solid Li2S2/Li2S on the negative electrode surface and attached to the negative electrode.
  • 761
  • 30 Aug 2022
Topic Review
Aurones
Aurones are part of the wide family of polyphenols. More specifically, they may be acknowledged as the lower structural counterparts of the best-known flavones, a subclass of flavonoids.
  • 761
  • 27 Jan 2022
Topic Review
Growth and Characterizations of SILAR-Deposited Thin Films
The prepared thin films could be used in lasers, cathodic ray tubes, solar cells, infrared windows, ultraviolet light emitting diodes, sensors, supercapacitors, biologic applications, and optoelectronic applications. The properties of these thin films strongly depend on the deposition techniques. Many investigations into the production of various types of thin films (by using the successive ionic layer adsorption and reaction (SILAR) method) were conducted. This method attracts interest as it possesses many advantages when compared to other deposition methods. For example, large area depositions could be carried out in any substrates at lower temperatures via inexpensive instruments; moreover, a vacuum chamber is not required, it has an excellent growth rate, and the unique film properties could be controlled.
  • 760
  • 26 Aug 2022
Topic Review
Polyhydroxyalkanoates (PHAs) as Biomaterials in Tissue Engineering
Polyhydroxyalkanoates (PHAs) are biodegradable and biocompatible biopolymers. These biomaterials have grown in importance in the fields of tissue engineering and tissue reconstruction for structural applications where tissue morphology is critical, such as bone, cartilage, blood vessels, and skin, among others. Furthermore, they can be used to accelerate the regeneration in combination with drugs, as drug delivery systems, thus reducing microbial infections. When cells are cultured under stress conditions, a wide variety of microorganisms produce them as a store of intracellular energy in the form of homo- and copolymers of [R]—hydroxyalkanoic acids, depending on the carbon source used for microorganism growth. 
  • 760
  • 03 Mar 2022
Topic Review
Nanocellulosic Materials for Oil Spill
Modern developments in cellulosic materials for oil spill removal are briefly showcased in this entry. Different types of lignocellulosic textures and different modification techniques and preparation methods are explained. Materials were classified into 3D-materials such as hydrophobic and oleophobic sponges and aerogels, or 2D-materials such as membranes, fabrics, films, and meshes. Majorly, 3D-materials showed clear correlation between porosity and density, and their absorption behavior. Moreover, it was shown that nanocellulosic precursors are not exclusively suitable to attain considerable absorption performance. This finding can lead to developments in cost- and energy-efficient production processes of future cellulosic oil spillage removal solutions.
  • 760
  • 27 Sep 2021
Topic Review
Self-Healing Elastomers
It is impossible to describe the recent progress of our society without considering the role of polymers; however, for a broad audience, “polymer” is usually related to environmental pollution. The poor disposal and management of polymeric waste has led to an important environmental crisis, and, within polymers, plastics have attracted bad press despite being easily reprocessable. Nonetheless, there is a group of polymeric materials that is particularly more complex to reprocess, rubbers. These macromolecules are formed by irreversible crosslinked networks that give them their characteristic elastic behavior, but at the same time avoid their reprocessing. Conferring them a self-healing capacity stands out as a decisive approach for overcoming this limitation. By this mean, rubbers would be able to repair or restore their damage automatically, autonomously, or by applying an external stimulus, increasing their lifetime, and making them compatible with the circular economy model.
  • 760
  • 26 May 2022
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