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2 Nanostructures
Published in It-Meng Low, Hani Manssor Albetran, Victor Manuel de la Prida Pidal, Fong Kwong Yam, Nanostructured Titanium Dioxide in Photocatalysis, 2021
It-Meng Low, Hani Manssor Albetran, Victor Manuel de la Prida Pidal, Fong Kwong Yam
TiO2 nanostructures have a wide range of environmental and energy applications [1]. Nanostructured TiO2 is a promising original production material for many applications because of its high specific area and electronic semiconductor properties, including photocatalytic, photochromic, photovoltaic, electroluminescence, electrochromic devices and sensors [1–3]. Examples of current and potential applications of these nanostructures are described as follows.
Nanostructures
Published in Elaine A. Moore, Lesley E. Smart, Solid State Chemistry, 2020
Elaine A. Moore, Lesley E. Smart
Nanostructures can be synthesized using top-down methods or bottom-up methods. In top-down methods, larger particles are broken down. In bottom-up methods, the nanostructures are built up from scratch from the constituent ions, atoms, or molecules.
Tunable Hydrogel Systems for Delivery and Release of Cell-Secreted and Synthetic Therapeutic Products
Published in Emmanuel Opara, Controlled Drug Delivery Systems, 2020
Kylie G. Nairon, Thomas DePalma, Hemamylammal Sivakumar, Aleksander Skardal
Although light-induced response has long been used for hydrogel formation, it has more recently been pursued as an external trigger for release. The UV and visible spectrum light wavelengths generally applied to initiate hydrogel crosslinking reactions are not viable stimuli due to their quick attenuation when traveling through skin and the negative side effects of UV radiation. NIR wavelengths, however, can overcome both of these challenges, and research has focused on designing hydrogel structures capable of responding to stimulation within this range. Systems have been designed to include NIR-absorbing nanoparticles and nanotubes, which convert the NIR light to thermal energy, causing the gel to contract or degrade and releasing enclosed molecules. Possible nanostructures include carbon nanotubes, gold nanorods, and polydopamine nanoparticles. A second approach converts the NIR to UV light, which is emitted locally and triggers reaction cascades much like standard hydrogel synthesis. To achieve this, upconversion nanoparticles (UCNPs) are incorporated into the polymer matrix, which is crosslinked by photocleavable bonds. When stimulated with NIR light, the UCNPs convert multiple NIR photons into a UV photon, cleaving the crosslinking bonds and degrading the hydrogel.63
Microbially synthesized nanoparticles and their applications in environmental clean-up
Published in Environmental Technology Reviews, 2022
Modhurima Misra, Soham Chattopadhyay, Ashish Sachan, Shashwati Ghosh Sachan
Nanostructures are fabricated using different conventional physico-chemical techniques, which can be categorized under two approaches – top down or bottom up. The top-down approach includes techniques such as chemical etching, mechanical milling and electro-explosion, while bottom up comprises laser pyrolysis, sol–gel processes and atomic/molecular condensation [79]. These techniques are highly expensive, energy-intensive and often use hazardous chemical reagents. Recently, the focus has shifted towards fabricating different nanostructures from plants, microbes or their products as a way of developing eco-friendly biogenic nanomaterials. The advantages of exploiting plants, for the synthesis of different NMs, include their safe handling, ease of availability and the presence of a wide range of phytochemicals such as aldehydes, ketones, amides, phenols, carboxylic acids, terpenoids and flavones, which play a dual role in metal reduction as well as in the stabilization of the synthesized NMs. Microbial synthesis is considered because these organisms are easy to manipulate in order to achieve desired NMs and the metal salt solution can be directly added to the microbial culture for the synthesis.
Nonlinear flexural free vibrations of size-dependent graphene platelets reinforced curved nano/micro beams by finite element approach coupled with trigonometric shear flexible theory
Published in Mechanics of Advanced Materials and Structures, 2022
Ganapathi Manickam, Prateek Gupta, Sarthak De, Vasudevan Rajamohan, Olivier Polit
Recent advancements in manufacturing technology have made possible the production of customizable structural elements in the size of a few nanometers. Sophisticated processes such as the arc-discharge and laser ablation allow for the production of single wall nanotubes (SWNTs) in limited quantities. On commercial scale, the nanostructures are produced using widely accepted processes such as that of the chemical vapor deposition (CVD) [1]. Recently, nanostructures have found their importance in various domains such as medicine, energy, tooling and engineering sectors due to their exceptional structural, electrical and chemical properties. Over the years, the nanostructures are forming components of resonators [2], field emission electron sources [3], LEDs [4], probes for scanning electron microscopes [5], sensors in chemical industries [6] and other numerous devices. Due to peculiar mechanical behavior of such nano-structural elements, an acute understanding of their behavior is required when coupled with various loading conditions. While experimental techniques are cost intensive, models based on molecular dynamics, atomistic modeling and density functional theory are computationally demanding. However, nonlocal continuum mechanics approaches provide an easier way to analyze a wide spectrum of behavior such as bending, vibration, buckling etc. Theories such as the strain gradient theory [7], couple stress theory [8, 9], and the nonlocal elasticity theory [10, 11] model the size-dependent effects by introducing small-scale parameters in the constitutive relations used while setting up the classical governing equations.
On the viscoelastic carbon nanotube mass nanosensor using torsional forced vibration and Eringen’s nonlocal model
Published in Mechanics Based Design of Structures and Machines, 2022
Farshad Khosravi, Seyyed Amirhosein Hosseini
Nanostructures consist of the structures that one of their dimensions is between 1 and 100 nanometer (s) (Adams and Barbante 2013). Nanotechnology is helpful to manufacture low-cost structures with no pollutants on the atomistic scale. It is also time-consuming to construct the molecular nanostructures (Wilson et al. 2002). Nanotechnology is used in drug delivery and imaging inside of the human body (Koo, Rubinstein, and Onyuksel 2005). It also has vast applications, including in food industries (Srinivas et al. 2010), textiles (Joshi, Bhattacharyya, and Ali 2008) and water treatment (Qu, Alvarez, and Li 2013). Nanoparticles have made progress to develop the nanoelectronics and smart materials and caused the diversity in structures from simple structure to complex ones (Shipway, Katz, and Willner 2000). Carbon nanotube (CNT) was invented by Iijima (Iijima 1991). CNTs can be combined with biomaterials in hybrid form to make bioelectronics systems. Also, biomolecules can be encapsulated in open-ended CNTs (Katz and Willner 2004). CNTs can be purified to be oxidized and remove the iron oxide (Strong et al. 2003). Hybrid nanostructured materials are useful for energy storage devices (Reddy et al. 2012), nanostructured gold in biomedical (Cobley et al. 2011), and zinc sulfide structures in field emitters (Fang et al. 2011).