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Topic Review
Keto–Enol Tautomerism
In organic chemistry, keto–enol tautomerism refers to a chemical equilibrium between a keto form (a ketone or an aldehyde) and an enol (an alcohol). The keto and enol forms are said to be tautomers of each other. The interconversion of the two forms involves the movement of an alpha hydrogen atom and the reorganisation of bonding electrons; hence, the isomerism qualifies as tautomerism. A compound containing a carbonyl group (C=O) is normally in rapid equilibrium with an enol tautomer, which contains a pair of doubly bonded carbon atoms adjacent to a hydroxyl (−OH) group, C=C-OH. The keto form predominates at equilibrium for most ketones. Nonetheless, the enol form is important for some reactions. The deprotonated intermediate in the interconversion of the two forms, referred to as an enolate anion, is important in carbonyl chemistry, in large part because it is a strong nucleophile. Normally, the keto–enol tautomerization chemical equilibrium is highly thermodynamically driven, and at room temperature the equilibrium heavily favors the formation of the keto form. A classic example for favoring the keto form can be seen in the equilibrium between vinyl alcohol and acetaldehyde (K = [enol]/[keto] ≈ 3 × 10−7). However, it is reported that in the case of vinyl alcohol, formation of a stabilized enol form can be accomplished by controlling the water concentration in the system and utilizing the kinetic favorability of the deuterium-produced kinetic isotope effect (kH+/kD+ = 4.75, kH2O/kD2O = 12). Deuterium stabilization can be accomplished through hydrolysis of a ketene precursor in the presence of a slight stoichiometric excess of heavy water (D2O). Studies show that the tautomerization process is significantly inhibited at ambient temperatures ( kt ≈ 10−6 M/s), and the half-life of the enol form can easily be increased to t1/2 = 42 minutes for first-order hydrolysis kinetics. Another exception is the 1,3-diketones, such as acetylacetone (2,4-pentanedione), which favor the enol form.
  • 3.6K
  • 24 Oct 2022
Topic Review
Weave Structure and Fabric Properties
Fabric structures are created by interlacing yarns or intermeshing loops to create two-dimensional (2D) flexible materials. The most prevalent structure is woven fabrics, which are made up of two sets of perpendicular yarns that are crossed and interwoven to form a coherent and stable structure.
  • 3.6K
  • 16 Sep 2022
Topic Review
Crosslinking Agent for on Cellulose-Based Hydrogels
Hydrogels are interlinked hydrophilic polymers that are insoluble in water but are capable of absorbing large amounts of water through the swelling process. During the swelling process, the polar groups in the polymer chain swiftly draw the first water molecules into the hydrogel network (bound water). The hydrogel network absorbs more water molecules due to the osmotic pressure of the interstitial water and free water. Both synthetic and natural polymers can be used to create hydrogels. Natural polymer-based hydrogels are typically chosen because of their excellent biocompatibility and biodegradability. In addition, natural polymers are less expensive than synthetic ones.  A crosslinking agent is used to strengthen the properties of the hydrogel. A chemical crosslinking agent is used more often than a physical crosslinking agent. In a chemical crosslinking agent, there are two types of crosslinking agents, which is synthetic and natural crosslinking agents. Hydrogels that utilize synthetic crosslinking agents have advantages, such as adjustable mechanical properties and easy control of the chemical composition. However, hydrogels that use natural crosslinking agents have better biocompatibility and less latent toxic effect.
  • 3.5K
  • 28 Sep 2022
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.
  • 3.5K
  • 22 Dec 2020
Topic Review
Nanotechnology in Warfare
Nanotechnology in Warfare is a branch of nano-science in which molecular systems are designed, produced and created to fit a nano-scale (1-100nm). The application of such technology, specifically in the area of warfare and defence, has paved the way for future research in the context of weaponisation. Nanotechnology unites a variety of scientific fields including material science, chemistry, physics, biology and engineering. Advancements in this area, have led to categorised development of such nano-weapons with classifications varying from; small robotic machines, hyper-reactive explosives, and electromagnetic super-materials. With this technological growth, has emerged implications of associated risks and repercussions, as well as regulation to combat these effects. These impacts give rise to issues concerning global security, safety of society, and the environment. Legislation may need to be constantly monitored to keep up with the dynamic growth and development of nano-science, due to the potential benefits or dangers of its use. Anticipation of such impacts through regulation, would 'prevent irreversible damages' of implementing defence related nanotechnology in warfare.
  • 3.5K
  • 02 Nov 2022
Topic Review
Contact Lens Materials - A Materials Science Perspective
Contact lens materials are typically based on polymer- or silicone-hydrogel, with additional manufacturing technologies employed to produce the final lens. These processes are simply not enough to meet the increasing demands from CLs and the ever-increasing number of contact lens (CL) users. New materials and engineering offer increasing functionality or improved properties over previous generations.
  • 3.5K
  • 27 Jan 2022
Topic Review
Metabolic N-Dealkylation and N-Oxidation
Metabolic reactions that occur at alkylamino moieties may provide insight into the roles of these moieties when they are parts of drug molecules that act at different receptors. N-dealkylation of N,N-dialkylamino moieties has been associated with retaining, attenuation or loss of pharmacologic activities of metabolites compared to their parent drugs. Further, N-dealkylation has resulted in clinically used drugs, activation of prodrugs, change of receptor selectivity, and providing potential for developing fully-fledged drugs.
  • 3.5K
  • 13 Apr 2021
Topic Review
Non-Medical Applications of Chitosan Nanocomposite Coatings
Millions of tons of crustaceans are produced every year and consumed as protein-rich seafood but the shells and other non-edible parts constituting about half the body mass are wasted. The crustacean shells are a prominent source of polysaccharide (chitin) and protein. Chitosan, a de-acetylated form of chitin obtained from the crustacean waste are used for a variety of medical applications. In recent times, it has also found use in food and paint industries including marine antifouling coatings, due to its characteristic properties, like solubility in weak acids, film-forming ability, pH-sensitivity, antifouling properties, biodegradability, and biocompatibility. Chitosan composite coatings in food, paint and water treatment solutions have been developed. In food industries, chitosan-based composite films and coatings are applied for prolonging the post-harvest life of fruits and vegetables, while anti-corrosion and self-healing properties are mainly explored for antifouling applications in paints and metal ion chelation and antifouling properties are useful for water treatment.
  • 3.5K
  • 29 Oct 2020
Topic Review
Acoustic Extinguishing
In the fire-extinguishing process, in principle, one of the components in the fire tetrahedron must be removed. For example, a natural gas fire occurring on a stovetop burner can be extinguished in various ways: Eliminating the fuel source by shutting off the gas supply may be the first option. Another option is to completely cover the flame to block any oxidizer that is present, such as oxygen in the air, during combustion.
  • 3.5K
  • 25 Mar 2022
Topic Review
Nanotechnology for the Next Generation of Sequencing
This communication aims at discussing strategies based on developments from nanotechnology focused on the next generation of sequencing (NGS). In this regard, it should be noted that even in the advanced current situation of many techniques and methods accompanied with developments of technology, there are still existing challenges and needs focused on real samples and low concentrations of genomic materials.
  • 3.4K
  • 18 Apr 2023
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