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Topic Review
4D Printable Smart Hydrogels for Drug Delivery
Hydrogels are three-dimensional crosslinked polymer network structures that can absorb and hold a large quantity of water while retaining a distinct shape. Among modern drug formulations, stimuli-responsive hydrogels, also known as "smart hydrogels," has attracted enormous attention. The fundamental characteristic of these systems is the capacity to change their mechanical properties, swelling capacity, hydrophilicity, permeability of bioactive molecules, etc., in response to a wide range of stimuli, including temperature, pH, light irradiation, magnetic field, biological factors, etc. On the other hand, the expeditious development of 3D printing technologies has revolutionized the fabrication of hydrogel systems for biomedical applications. By combining these two aspects, 4D printing (i.e., 3D printing of smart hydrogels) has emerged as a new promising platform for the development of novel drug delivery systems, which release active ingredients in response to internal or external stimuli.
  • 973
  • 01 Nov 2022
Topic Review
Smart Bioinks for Printing Human Tissue Models
A bioink is a mixture of materials and biological molecules or cells to be used for bioprinting. Most bioinks are hydrogels, highly hydrated polymeric networks used to homogenously encapsulate cells by mimicking the natural extracellular matrix found in vivo. Hydrogels must meet certain characteristics to ensure they can support cell survival and function.
  • 973
  • 25 Apr 2022
Topic Review
Hydrosilylation Reactions Catalyzed by Rhenium
Hydrosilylation is a very versatile transformation consisting of the addition of a hydrosilane (H-SiR3) to an unsaturated bond. Organosilicon compounds have found widespread applications in our daily lives in silicon-based materials such as silicon rubbers, adhesives, paper release coating, and so forth. In addition, hydrosilylation is an atom economic reaction to access valuable organosilane intermediates for fine chemical synthesis
  • 973
  • 20 May 2021
Topic Review
Polymer–Metal Composites Materials for Healthcare Device
An ideal medical implant requires optimized properties on both bulk and microscopic scale that can hardly be accomplished by using a single material. Metallic implants such as titanium-based implants possess excellent mechanical properties in general but suffer from corrosion; polymeric implants can be multifunctional and biodegradable, however, difficult to provide some crucial mechanical properties like ductility. With the advance in polymer science and metallurgy, the polymer–metal composite materials serve as an emerging class of healthcare device with optimized bulk and microscopic properties, such polymer–metal composite devices provide good mechanical support, good bio-integration, good hygiene, and minimize bacterial infection and reduced hypersensitivity reactions.
  • 973
  • 27 Sep 2022
Topic Review
Atomic Layer Deposition on 2D Materials
Atomic layer deposition (ALD) of high-κ dielectrics on two-dimensional (2D) materials (including graphene and transition metal dichalcogenides) still represents a challenge due to the lack of out-of-plane bonds on the pristine surfaces of 2D materials, thus making the nucleation process highly disadvantaged. The typical methods to promote the nucleation (i.e., the predeposition of seed layers or the surface activation via chemical treatments) certainly improve the ALD growth but can affect, to some extent, the electronic properties of 2D materials and the interface with high-κ dielectrics. Hence, direct ALD on 2D materials without seed and functionalization layers remains highly desirable. In this context, a crucial role can be played by the interaction with the substrate supporting the 2D membrane. In particular, metallic substrates such as copper or gold have been found to enhance the ALD nucleation of Al2O3 and HfO2 both on monolayer (1 L) graphene and MoS2. Similarly, uniform ALD growth of Al2O3 on the surface of 1 L epitaxial graphene (EG) on SiC (0001) has been ascribed to the peculiar EG/SiC interface properties.
  • 972
  • 15 Dec 2021
Topic Review
Resistive Random-Access Memory
Resistive random access memory (RRAM), also often referred to as a memristor, is a non-volatile memory made from the simple structure of a metal–insulator–metal (MIM) sandwich, which is generally integrated into an elementary crossbar circuit. Resistive random access memory stands out among memory technologies due to its scalability, high-speed operation, and low power consumption. 
  • 972
  • 14 Mar 2023
Topic Review
Applications of Chitosan
Public health, production and preservation of food, development of environmentally friendly (cosmeto-)textiles and plastics, synthesis processes using green technology, and improvement of water quality, among other domains, can be controlled with the help of chitosan. This aminopolysaccharide is recognized as safe and produced from an abundant and renewable source (chitin). Chitosan exhibits advantageous properties, such as biocompatibility, biodegradability, antimicrobial effect, mucoadhesive properties, film-forming capacity, elicitor of plant defenses, coagulant-flocculant ability, synergistic effect and adjuvant along with other substances and materials. In part, its versatility is attributed to the presence of ionizable and reactive primary amino groups that provide strong chemical interactions with small inorganic and organic substances, macromolecules, ions, and cell membranes/walls. Hence, chitosan has been used either to create new materials or to modify the properties of conventional materials applied on an industrial scale.
  • 971
  • 03 Feb 2023
Topic Review
High-Entropy Alloys
Microstructural phase evolution during melting and casting depends on the rate of cooling, the collective mobility of constituent elements, and binary constituent pairs. Parameters used in mechanical alloying and spark plasma sintering, the initial structure of binary alloy pairs, are some of the factors that influence phase evolution in powder-metallurgy-produced HEAs. Factors such as powder flowability, laser power, powder thickness and shape, scan spacing, and volumetric energy density (VED) all play important roles in determining the resulting microstructure in additive manufacturing technology. Large lattice distortion could hinder dislocation motion in HEAs, and this could influence the microstructure, especially at high temperatures, leading to improved mechanical properties in some HEAs. Mechanical properties of some HEAs can be influenced through solid solution hardening, precipitation hardening, grain boundary strengthening, and dislocation hardening. Despite the HEA system showing reliable potential engineering properties if commercialized, there is a need to examine the effects that processing routes have on the microstructure in relation to mechanical properties. 
  • 971
  • 09 Jun 2021
Topic Review
Synthetic Polymers
Unlike natural polymers, the chemical composition, functional group type and extent of functionalization, molecular weight, charge density and distribution, degradation and stability of synthetic polymers can be engineered to maximize antiviral activity against a specific virus type.
  • 971
  • 05 May 2022
Topic Review
Nanostructures GaAs Solar Cells
At present, the world is now passing a very far different time than normal situation due to the COVID-19 pandemic crisis. The global life-style and human civilization is currently progressing with down-stream that affecting almost every sectors necessary for human civilizations except the current environmental situation. To control the COVID-19 spreading, most of the countries are following lockdown process that reduces human mobility, thus reducing the CO2 emission to the environment. Though the COVID-19 pandemic is a blessing for the present environment, however, the post-COVID world will face a massive thrust of energy and only conventional energy resources may not be enough to mitigate the energy demands. Solar power generation technology mainly the photovoltaic (PV) systems and their advancement can be the leading possibilities to minimize the gap between the power demand and generation. It is now time to think how we can improve the PV power generation in future and the post-COVID world. In this encyclopaedia communication, we report on Nano-technological approach to improve the conversion efficiency of GaAs solar cells. We have designed and optimized several types of nano-structured assemblies that can be implemented to reduce the front surface incident light reflection losses thus can assist to improve the conversion efficiency of GaAs solar cells.
  • 971
  • 02 Nov 2020
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