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Topic Review
Acoustic Properties of Natural-fiber-based Composites
Recent advancement in controlling noise through sound absorption provides an opportunity to investigate various porous materials including fiber-based composites. Natural-fiber-based composites exhibit relatively good sound absorption capability due to their porous structure. Surface modification by alkali treatment can enhance the sound absorption performance. These materials can be used in buildings and interiors for efficient sound insulation. Natural-fiber-based composites have advantages such as high abrasive resistance, low emission of toxic fumes with heat, high specific strength, light weight, low cost, and eco-friendliness. Very rapid growth has been observed in the innovations and use of natural-fiber-based materials and composites for acoustic applications.
  • 3.8K
  • 24 Aug 2021
Topic Review
Czochralski Process
The Czochralski process is a method of crystal growth used to obtain single crystals of semiconductors (e.g. silicon, germanium and gallium arsenide), metals (e.g. palladium, platinum, silver, gold), salts and synthetic gemstones. The process is named after Polish scientist Jan Czochralski, who invented the method in 1915 while investigating the crystallization rates of metals. He made this discovery by accident: instead of dipping his pen into his inkwell, he dipped it in molten tin, and drew a tin filament, which later proved to be a single crystal. The most important application may be the growth of large cylindrical ingots, or boules, of single crystal silicon used in the electronics industry to make semiconductor devices like integrated circuits. Other semiconductors, such as gallium arsenide, can also be grown by this method, although lower defect densities in this case can be obtained using variants of the Bridgman-Stockbarger technique.
  • 3.8K
  • 24 Nov 2022
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.
  • 3.8K
  • 24 Oct 2022
Topic Review
Socioeconomic and Environmental Impacts of High-Speed Rail
Countries considering high-speed rail (HSR) developments face enormous challenges because of their high deployment cost, environmental obstacles, political opposition, and their potentially adverse effects on society. Nevertheless, HSR services are importantly sustainable that can have positive and transformative effects on the economic growth of a nation. 
  • 3.8K
  • 22 Nov 2021
Topic Review
Prosumption as Basic Market Force in Modern Economy
The term “prosumption” is a portmanteau of production and consumption. It refers to a process where a consumer takes over some of the activities previously performed by a producer, usually by directly involving themselves in the design and production of various goods or services. Prosumption is the basic market force in the modern economy.
  • 3.8K
  • 07 Dec 2022
Topic Review
Sustainability and Sharing Economy
The sharing economy is usually related to sustainability, and it is framed as: (a) an economic opportunity, (b) a more sustainable form of consumption and (c) a pathway to an equitable and sustainable economy [1]. 
  • 3.8K
  • 27 Oct 2020
Topic Review
Additive Manufacturing of Turbine Blades
Additive manufacturing is a technology of transforming a 3D prototype to a physical one directly by successive addition of the required material in a layer-by-layer manner. This technique helps to manufacture the turbine blade which is the revolution of green technology for high temperature engine parts.
  • 3.8K
  • 11 Oct 2022
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. 
  • 3.8K
  • 16 Mar 2021
Topic Review
Architecture and Challenges of Industrial Internet of Things
The inherent complexities of Industrial Internet of Things (IIoT) architecture make its security and privacy issues becoming critically challenging. Numerous surveys have been published to review IoT security issues and challenges. The studies gave a general overview of IIoT security threats or a detailed analysis that explicitly focuses on specific technologies. However, recent studies fail to analyze the gap between security requirements of these technologies and their deployed countermeasure in the industry recently. Whether recent industry countermeasure is still adequate to address the security challenges of IIoT environment are questionable.
  • 3.8K
  • 21 Oct 2021
Topic Review
Adaptation of Seed Germination
Environmental conditions are the basis of plant reproduction and are the critical factors controlling seed dormancy and germination. Global climate change is currently affecting environmental conditions and changing the reproduction of plants from seeds. Disturbances in germination will cause disturbances in the diversity of plant communities. Models developed for climate change scenarios show that some species will face a significant decrease in suitable habitat area. Dormancy is an adaptive mechanism that affects the probability of survival of a species. The ability of seeds of many plant species to survive until dormancy recedes and meet the requirements for germination is an adaptive strategy that can act as a buffer against the negative effects of environmental heterogeneity. The influence of temperature and humidity on seed dormancy status underlines the need to understand how changing environmental conditions will affect seed germination patterns. 
  • 3.8K
  • 06 Feb 2021
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