Topic Review
Magneto-Fluorescent Nanosystems for Biomodal Imaging
The various imaging techniques used in clinic have advantages and disadvantages. The advent of nanotechnology offers the possibility to combine several imaging agents within the same nano-object. This will allow to perform multi-imaging and thus obtain additional information during the same clinical procedure. Here, the focus are made on the potentialities of biomodal agents labeled for MRI and optical imaging. The three main associations for obtaining magneto-fluorescent objects will be presented: (1) association by covalent bonding; (2) encapsulation in matrices; (3) dispersion in nanoassemblies.
  • 1152
  • 13 Oct 2021
Topic Review
Full-Color Realization of Micro-LED Displays
Emerging technologies, such as smart wearable devices, augmented reality (AR)/virtual reality (VR) displays, and naked-eye 3D projection, have gradually entered our lives, accompanied by an urgent market demand for high-end display technologies. Ultra-high-resolution displays, flexible displays, and transparent displays are all important types of future display technology, and traditional display technology cannot meet the relevant requirements. Micro-light-emitting diodes (micro-LEDs), which have the advantages of a high contrast, a short response time, a wide color gamut, low power consumption, and a long life, are expected to replace traditional liquid-crystal displays (LCD) and organic light-emitting diodes (OLED) screens and become the leaders in the next generation of display technology. However, there are two major obstacles to moving micro-LEDs from the laboratory to the commercial market. One is improving the yield rate and reducing the cost of the mass transfer of micro-LEDs, and the other is realizing a full-color display using micro-LED chips. This study will outline the three main methods for applying current micro-LED full-color displays, red, green, and blue (RGB) three-color micro-LED transfer technology, color conversion technology, and single-chip multi-color growth technology, to summarize present-day micro-LED full-color display technologies and help guide the follow-up research.
  • 1071
  • 22 Dec 2020
Topic Review
Electrical Conductivity of Nanoparticle-Enhanced Fluids
Research on nanoparticle-enhanced fluids’ electrical conductivity is at its beginning at this moment and the augmentation mechanisms are not fully understood. Basically, the mechanisms for increasing the electrical conductivity are described as electric double layer influence and increased particles’ conductance. Another idea that has resulted from state of the art is that the stability of nanofluids can be described with the help of electrical conductivity tests, but more coordinated research is needed. Concluding, this analysis has shown that a lot of research work is needed in the field of nanofluids’ electrical characterization and specific applications.
  • 1049
  • 23 Oct 2020
Topic Review
Copper-Based Conductive Inks
Silver (Ag), gold (Au), and copper (Cu) have been utilized as metals for fabricating metal-based inks/pastes for printed/flexible electronics. Among them, Cu is the most promising candidate for metal-based inks/pastes. Cu has high intrinsic electrical/thermal conductivity, which is more cost-effective and abundant, as compared to Ag. Moreover, the migration tendency of Cu is less than that of Ag. Thus, recently, Cu-based inks/pastes have gained increasing attention as conductive inks/pastes for printed/flexible electronics. We can divide Cu-based inks/pastes into four categories from the viewpoints of Cu sources: (i) traditional micron-sized flake/powder type, (ii) nanoparticle type, (iii) nanowire type, and (iv) precursor ion type. However, the disadvantages of Cu-based inks/pastes are their instability against oxidation under an ambient condition and tendency to form insulating layers of Cu oxide, such as cuprous oxide (Cu2O) and cupric oxide (CuO). The formation of the Cu oxidation causes a low conductivity in sintered Cu films and interferes with the sintering of Cu particles. The surface and interface designs for Cu-based conductive inks/pastes are important strategies for the oxidation resistance of Cu and low-temperature sintering to produce highly conductive Cu patterns/electrodes on flexible substrates. The surface control approaches include surface designs by polymers, small ligands, core-shell structures, and surface activation. The Cu-based mixed inks/pastes offer improved performances compared with the single use of each component.
  • 1043
  • 07 Sep 2020
Topic Review
Spider Silk with Inorganic Nanomaterials
High-performance functional biomaterials are becoming increasingly requested. Numerous natural and artificial polymers have already demonstrated their ability to serve as a basis for bio-composites. Spider silk offers a unique combination of desirable aspects such as biocompatibility, extraordinary mechanical properties, and tunable biodegradability, which are superior to those of most natural and engineered materials. Modifying spider silk with various inorganic nanomaterials with specific properties has led to the development of the hybrid materials with improved functionality. The purpose of using these inorganic nanomaterials is primarily due to their chemical nature, enhanced by large surface areas and quantum size phenomena. Functional properties of nanoparticles can be implemented to macro-scale components to produce silk-based hybrid materials, while spider silk fibers can serve as a matrix to combine the benefits of the functional components. Therefore, it is not surprising that hybrid materials based on spider silk and inorganic nanomaterials are considered extremely promising for potentially attractive applications in various fields, from optics and photonics to tissue regeneration. This review summarizes and discusses evidence of the use of various kinds of inorganic compounds in spider silk modification intended for a multitude of applications. It also provides an insight into approaches for obtaining hybrid silk-based materials via 3D printing.
  • 1034
  • 29 Sep 2020
Topic Review
Toxicity of Titanium Compounds
Titanium and its compounds are broadly used in both industrial and domestic products, including jet engines, missiles, prostheses, implants, pigments, cosmetics, food, and photocatalysts for environmental purification and solar energy conversion. Although titanium/titania-containing materials are usually safe for human, animals and environment, increasing concerns on their negative impacts have been postulated. We have reported the state of knowledge about toxicity of titanium, its alloys and oxides. Due to the alarming increase in titania/titanium applications in various daily care products and medical treatment (e.g. dental implants) the possible toxicity and environmental impact should be considered.  The collected data might allow to identify some harms associated with using of titania and titanium compounds.
  • 1021
  • 21 Feb 2021
Topic Review
Neuromorphic Computing
Neuromorphic computing systems aims at processing information in a way similar to the human brain. Instead of a conventional von Neumann computer, a neuromorphic system generally relies on a neural network, where the memory and the processing elements are intimately co-located within the same hardware. Neuromorphic computing takes advantage of computational memories, which can both store and process data via physical laws within the device and/or the circuit. This entry summarizes the history and main concepts of neuromorphic computing, including both deep neural networks (DNNs) which are adopted for extensive artificial intelligence tasks, such as driverless cars, and spiking neural networks (SNNs), which aim at a more realistic brain-inspired computation. 
  • 984
  • 22 Jan 2021
Topic Review
Catalyst Design via Colloidal Synthesis
Supported nanoparticles are commonly applied in heterogeneous catalysis. The catalytic performance of these solid catalysts is, for a given support, dependent on the nanoparticle size, shape, and composition, thus necessitating synthesis techniques that allow for preparing these materials with fine control over those properties. Such control can be exploited to deconvolute their effects on the catalyst’s performance, which is the basis for knowledge-driven catalyst design. In this regard, bottom-up synthesis procedures based on colloidal chemistry have proven successful in achieving the desired level of control for a variety of fundamental studies. This article aims to give an overview of recent progress made in this synthesis technique for the application of controlled catalytic materials in gas-phase catalysis. The focus goes to mono- and bimetallic materials, as well as to recent efforts in enhancing their performance by embedding colloidal templates in porous oxide phases.
  • 982
  • 12 May 2021
Topic Review
Carbon Dots: Synthesis and Properties
Carbon dots (CDs) are zero-dimensional optically active carbon-based nanomaterials with a size of less than 10 nm. The material property of the CD is largely linked to the various bottom-up & top-down synthesis approaches, including surface passivation and functionalization, and the carbon precursors. The CDs can be engineered to enhance the chemical and physical functional properties by doping with heteroatom such as nitrogen, phosphorus, sulfur, fluorine, and boron. Because of its various advantageous properties, CDs are utilized in the field of chemical/biological sensing, bioimaging, and drug delivery. These nanosized CDs can change their light emission properties in response to various external stimuli such as pH, temperature, pressure, and light. The CD’s remarkable stimuli-responsive smart material properties have recently stimulated massive research interest for their exploitation to develop various sensor platforms. 
  • 950
  • 16 Mar 2021
Topic Review
Fly Ash
Fly ash or coal fly ash causes major global pollution in the form of solid waste and is classified as a “hazardous waste”, which is a by-product of thermal power plants produced during electricity production. Si, Al, Fe Ca, and Mg alone form more than 85% of the chemical compounds and glasses of most fly ashes. Fly ash has a chemical composition of 70–90%, as well as glasses of ferrous, alumina, silica, and CaO. Therefore, fly ash could act as a reliable and alternative source for ferrous, alumina, and silica. The ferrous fractions can be recovered by a simple magnetic separation method, while alumina and silica can be extracted by chemical or biological approaches. Alumina extraction is possible using both alkali- and acid-based methods, while silica is extracted by strong alkali, such as NaOH. Chemical extraction has a higher yield than the biological approaches, but the bio-based approaches are more environmentally friendly. Fly ash can also be used for the synthesis of zeolites by NaOH treatment of variable types, as fly ash is rich in alumino-silicates. The present review work deals with the recent advances in the field of the recovery and synthesis of ferrous, alumina, and silica micro and nanoparticles from fly ash.
  • 914
  • 06 Apr 2021
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