Carbon nanotubes diverse applications have been discussed in the present study. Carbon nanotubes are a promising material in all façades of life, be it environment, electrical, electronics, biomedical energy, food technology applications, etc. Carbon nanotubes open new avenues to improve the environment, control pollution, and used in various fields. Increase in the population, urbanization and industrialization create several types of pollution. Carbon nanotubes solve various problems including environmental issues, pollution, bio-medicals, etc. It becomes an inevitable material for the present and future. In this review article, carbon nanotube applications to solve water purification, water disinfection, electrical and electronic applications, biomedical energy, or in-air purification have been discussed. A plethora of carbon nanotube applications in various fields have been discussed in articles covering the fields of water purification, biomedical applications in electrical/electronic applications, agricultural yields, etc. Eleven different case studies have been discussed in the paper and testimony of the use of CNTs in various fields was given by the patent trend. Graphical Abstract

Electrospinning has received wide attention for the preparation of uniform diameter nanofibers (ranging from 5 nm to several hundred nanometers) in films with random as well as aligned fashions of the fibers of various materials for use in biomedical applications. Electrospinning research has provided an in-depth understanding of the preparation of light weight, ultrathin, porous, biofunctional curcumin/gelatin nanofibers having applications in wound dressing, drug release, tissue engineering, etc. In the first half of this article, prior research on electrospun curcumin/gelatin nanofibers is reviewed in depth with nanofibers being desired due to their low diameters since these would have then large surface area to volume ratio and enough film porosity as well as improved mechanical (tensile) strength so that when prepared as mats these nanofibers (having high biocompatibility) could be used for sustained release of curcumin and oxygen to wounds during healing. The synthesis of ultrathin nanofibers (having minimum average diameter) is not a simple task unless numerical investigation is carefully done in the first half of this research article. The authors research described here examined the effects of critical process parameters (in the second half of the paper) such as distance between the spinneret and collector, flow rate, voltage and solution viscosity, on the preparation of uniform and ultrathin nanofibers using scanning electron microscopy (SEM) for characterization of the nanofibers. A 2 ^k factorial design of experiment was found to be a suitable and efficient technique to optimize the critical process parameters used in the preparation of the biofunctional nanofibers with the purpose of having applications in the treatment of problematic wounds such as diabetic chronic ulcers. After parametric investigation, the distance, flow rate and voltage when taken together, were found to have the most significant contributions to the preparation of minimum diameter nanofibers. The primary objective of this research was fulfilled with the development of ultrathin curcumin/gelatin nanofibers having a 181 nm (181 ± 66 nm) average diameter using the optimized setting of a solution having 1.5% gelatin, and 1% curcumin in 10 ml of 98% concentrated formic acid, with the electrospining unit having a voltage of 10 KV, distance from the spinneret to collector drum of 15 cm, flow rate of 0.1 ml h⁻¹, viscosity of 65 cP and drum collector speed of 1000 rpm. However, the lowest average diameter of nanofiber was measured around 147 nm (147 ± 34 nm) which was prepared at a higher voltage, such as 15 KV (at 10 cm distance, 0.15 ml h⁻¹ flow rate and 65 cP viscosity) using the solution. The design of this research paper is based on the view that merely optimization of biofunctional nanofibers may not fully satisfy researchers/engineers unless they are also provided with sufficient information about (a) the entire electrospinning mechanism (numerical investigations of the mechanism) to have better control over preparation of ultrathin nanofibers, and (b) applications of the resulting ultrathin biofunctional nanofibers while fabricating nanofibrous mats (as used now-a-days) for sustained release of curcumin during the critical hours of wound healing and other biomedical applications.

4D printed objects are indexed under additive manufacturing (AM) objects.