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Combining Melt Electrowriting (MEW) and other Electrospinning-based Technologies with 3D Printing to Manufacture Multiphasic Conductive Scaffold for Tissue Engineering
Published in K.M. Praveen, Rony Thomas Murickan, Jobin Joy, Hanna J. Maria, Jozef T. Haponiuk, Sabu Thomas, Electrospun Nanofibers from Bioresources for High-Performance Applications, 2023
Advantages: It allows working with small amounts of material.It allows working with materials liquid or viscous at room temperature.The material can be driven by the pressure of inert gases, such as nitrogen or carbon dioxide, to avoid oxidation and or cross-linking.
Foam Injection Molding
Published in S. T. Lee, Polymeric Foams, 2022
PBAs are liquids or gases if they are stable at plastic processing temperature and room temperatures, such as water, argon (Ar), N2, and CO2. Generally, CO2 and N2 are by far the most widely used in the FIM. The inert gases are materials and energy saver with no global warming or ozone depletion potential. Gas needs to be injected into a barrel where the plastic must be in a molten state and the melt pressure is lower than the gas pressure in the outlet of gas injector. Then, gas will be fully mixed and dissolute into the plastic melt under certain pressure before it is injected into the mold.
Dust Control in the Workplace
Published in John D. Constance, Controlling In-Plant Airborne Contaminants, 2020
Dust collectors should be located outdoors or in detached work areas that are provided with adequate explosion vents. Grinding and conveying equipment may be protected by purging with an inert gas such as nitrogen that will reduce the normal oxygen content below the explosive limit. The inert gas may be obtained from inert gas generators, nitrogen bottle systems, or carbon dioxide storage systems. Refer to Table 3.2 for a listing of dust explosion pressures. Maximum allowable oxygen percentages in dusty environments may be obtained from the National Fire Protection Association (NFPA) publications.
Parametric optimisation of supercritical CO2 thermal-hydraulic characteristics in micro-channels using response surface methodology
Published in Australian Journal of Mechanical Engineering, 2023
N.T. Rao, A. N. Oumer, M.M. Noor, K. Kadirgama, F. Basrawi, J. P. Siregar
Emission of carbon dioxide (CO2) to the Earth’s atmosphere is increasing due to some of the human activities such as energy generation resulting in the release of CO2 through the burning of fossil fuels. Moreover, CO2 release can occur from solid wastes, tree and wood products, and from some chemical reactions. As part of the biological carbon cycle, the trees absorb CO2 for the photosynthesis process. However, the reduction in the number of trees due to logging affects the biological carbon cycle, which causes the concentration of CO2 gas in the atmosphere to increase. CO2 is an environmentally friendly gas and has low ozone-depleting potential (ODP) but has effective global warming potential (GWP). It can be used in many engineering applications such as refrigeration and cooling (in its solid and liquid form), as an inert gas in chemical processes, in fire extinguishers, and in the manufacture of casting moulds to enhance their hardness.
Effect of the sudden change of ambient atmosphere on free radicals in coal body by CO2 fire prevention gas injection
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Jinrui Miao, Shengqiang Yang, Xiaoyuan Jiang, Zhenshan Hou, Huadi Shao
The apparent activation energy required for the low-temperature oxidation process of coal in an oxygen atmosphere was shown to be smaller and increased with the oxygen concentration by solving the apparent activation energy for various atmospheres (Gao, Chang, and Shen 2017; Li et al. 2016). The inert gases are capable of reducing the oxygen concentration to below the concentration that allows combustion. The continuous decreases of oxygen concentration and temperature are accompanied by the gradual decline of heat production rate of combustible (Deng et al. 2018; Kus, Misz-Kennan, and Iccp 2017). CO and CO2 are the products of sufficient and insufficient oxidation of coal, respectively (Su et al. 2017; Zhu et al. 2020). Compared with the condition in pure air, coal combustion in inert gases corresponds to faster oxygen consumption and lower CO and CH4 production rates during low-temperature oxidation (Zhang et al. 2018). The alterations in free radical functional groups in the coal bodies directly impact macroscopic characteristics like the emission of gaseous products during the oxidation of the coal bodies (Ma et al. 2020). Researches on the mechanism of CSC have went further from the macroscopic characteristics to the micro-structure through the use of many experiments like small-angle X-ray diffraction (XRD) (Wang et al. 2021) Fourier transform infrared spectroscopy (FTIR) (Yang et al. 2023) and electronic energy spectrum analysis (XPS) (Levi et al. 2015). The CSC process involves progressive chain reactions of different active functional group structural units and free radicals with oxygen (Cai et al. 2021) non-free functional group structural units and free radicals, and between free radicals themselves (Lei et al. 2020; Wu et al. 2018). Free radical reactions take place as soon as after contact between coal and oxygen at room temperature (Qi et al. 2019, 2020). The reaction between oxygen and the reactive groups in coal produces new free radicals, increasing the number of free radicals in the coal (Xi et al. 2023). The free radical reaction is highly temperature sensitive, and the presence of oxygen intensifies the free radical reaction in coal (Li et al. 2018; Liu et al. 2014). Active radicals can unite to produce stable chemical structures, whereas stable radicals can go for a long time without reacting (He et al. 2017; Zhou et al. 2017). The main reaction in low-temperature oxidation is the reaction between newly activated radicals and oxygen. After that, stable radicals join the reaction to produce more free radicals as the free radical chain reaction and chain excitation quicken with the temperature rise (Chen et al. 2021; Li et al. 2016).