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Principles of Green Chemistry
Published in Sanjay K. Sharma, Hasan Demir, Green Chemistry in Scientific Literature, 2019
In recent years, the polymerization reaction has also improved to greener non-hazardous solvents and production with biodegradable polymers due to strict regulations and concerns about waste of the polymer production process and VOCs and hazardous gas. Supercritical fluids (CO2, etc.) can be used in polymerization reactions. Supercritical fluids having gas-like diffusivities and liquid-like densities can change in solvent density with small fluctuation in temperature or pressure. This type of reaction can be beneficial due to the utilization of inexpensive and non-toxic fluids such as CO2 (Dubé and Salehpour 2014). High-pressure chemistry (i.e., Q-tube) proposes faster, cheaper, safer, and greener reactions more than conventional techniques. Figure 3.11 presents comparisons of the high-pressure reactor versus microwave (MW) reactor. For all compounds, conversions and yields values of the Q-tube high-pressure reactor are higher than that of the MW reactor. However, both techniques, high-pressure Q-tube and microwave reactors, surpass in the manner of reaction time and yield of reaction from conventional heating reactors (Nacca et al. 2017).
The one-dimensional hydrogenic impurity states confined at one end of the InAs quantum well
Published in Philosophical Magazine, 2022
De-hua Wang, Xue He, Xue Liu, Bin-hua Chu, Wei Liu, Meng-meng Jiao
Studies of the quantum confined systems have gained great interest due to their relevance in the design of semiconductor devices and synthesis of new materials [1]. The idea of the quantum confined systems was developed in the early 1930s by Michels et al., who put forward a theoretical model of confined the hydrogen atom in a spherical microcavity to simulate the high pressure environment [2,3]. Using this model, many experiments involving atoms under high pressure and in metallofullerenes have been analysed [4]. At the same time, a diverse set of researches related to the quantum confined system have been done during the last several decades. For example, Patil and Varshni studied the energy spectra of H, He and Li atoms confined to a spherical microcavity [5]. Ley-Koo has conducted some researches on the symmetry breakings and super-integrability of the confined atoms and molecules [6]. Suryanarayana et al reported the splitting of a degenerate energy level of the one-electron atom in the presence of an impenetrable cavity [7]. It was found that the energy levels of quantum confined atoms are very different from those in the free space. The variations in the energy level structure of the quantum confined atoms are very important in the field of solid state physics, astrophysics and high pressure chemistry and physics, etc. Furthermore, Aquino and his group calculated some physical properties of the confined hydrogen atom in the spherical microcavity, such as the hyperfine splitting constant, the nuclear magnetic screening parameter, the polarizability, and the pressure induced by the microcavity [8–10]. Later, the Shannon entropy for a hydrogen atom confined in different external environment has been studied by many researchers [11–13].