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Mechanisms of Action in Bioelectromagnetics
Published in Ben Greenebaum, Frank Barnes, Bioengineering and Biophysical Aspects of Electromagnetic Fields, 2018
Cells receive some information from their surroundings when a signaling molecule binds to a receptor on the cell surface, the receptor-ligand binding process. If the binding is affected by a the presence of the field, subsequent biochemistry is also affected, quite likely multiplied in effect because of the signaling nature of the ligand molecule. Chiabrera and Rodan (1984) assumed such an electromagnetic influence and analyzed the subsequent rate equations. The calculated curves compared favorably with measurements of parathyroid hormone-induced activation of adenylate cyclase. A subsequent analysis in context of the ion motion near the membrane in specific fields relevant to “cyclotron resonance” indicated that water viscosity changes, which can exist near the membrane, could produce effects (Biancno et al., 1988). As noted in Chapter 5, the probability equation for a chemical reaction occurring during a collision between two molecules includes a steric factor which represents whether molecules are in the correct range of relative orientation. This factor could change if applied fields affect the molecules so as to change this range.
Studies on the Interaction Between Polyethylene Oxide and Cationic Gemini/Conventional Surfactants
Published in Indian Chemical Engineer, 2018
Assuming complete monolayer formation at cmc, the area of exclusion per surfactant monomer (Amin) at the air/water interface can be calculated from the following relation:where Amin is in A2 molecule−1 and NA is the Avogadro’s number. The Amin values increase with PEO concentration, which is probably due to the strong electrostatic repulsions and more steric factor between surfactants and polymer, that is, with the addition of PEO, lesser number of surfactant molecules are adsorbed at the air/water interface, leading to the availability of larger space per molecule at the interfacial region [2,4,7]. The Amin values for CTAB are found to be lower than that of gemini surfactants as shown in Fig. 5. Thus, it can be seen that the Amin values follow the sequence G5 > G6 > CTAB among the studied cationic surfactants. The values of surface parameters for CTAB, G5 and G6 at different temperatures are given in Tables 1–3. The highest value of Amin shows the close fitting of surfactants’ head on micelle. The closest fitting of surfactant heads increases with the concentration of polymer as observed earlier [4,7].
On the Radiative, Diffusion and Chemical Effects of Soot Formation in a Nonsmoking Laminar Ethylene Diffusion Flame
Published in Combustion Science and Technology, 2023
Liang Qiu, Yang Hua, Yejian Qian, Xiaobei Cheng
The DLR mechanism (Slavinskaya and Frank 2009) was employed in this work, which has been validated by the flame speed of CH4/air and C2H4/air mixture, as well as the species concentrations in methane and ethylene flames. It should be noted that the NOx sub-mechanism was not considered in the present work. CoFlame code (Eaves et al. 2016) was employed to calculate the combustion and soot evolution process in laminar coflow flames, where soot dynamics are solved by a fixed sectional method. The detailed soot model can be found in (Eaves et al. 2016), and only a brief introduction is given here. Soot aggregates are assumed to be composed of spherical primary particles of equal size with a constant fractal dimension of 1.8 (Eaves et al. 2016; Qiu et al. 2018). Particle inception is considered as the dimerization of benzo[a]pyrene, secondary benzo[a]pyrenyl, and benzo(ghi)fluoranthene. Since all the three species are PAHs with five rings, they can be marked as A5. The model also consists of HACA surface growth, surface condensation of A5 (A5-soot condensation efficiency was set to 0.5), coagulation due to particle collision (the coagulation efficiency of two aggregates is set to 0.2), oxidation by O2/OH and oxidation-induced fragmentation (1:1 fragmentation pattern). The rates of HACA reactions can be found in (Eaves et al. 2016). The steric factor α, an empirical parameter that reconciles the inaccuracies associated with treating sites on the surface of a soot particle like a site on a PAH molecule, and is adjusted to 1.0 for all conditions. O2 oxidation is based on the oxidation of phenyl, while OH oxidation is based on a collision theory, which uses a constant collision efficiency between soot of OH of 0.13. Soot diffusion accounts for normal diffusion and thermophoresis. The radiation is calculated using a discrete-ordinates method (DOM) and a statistical narrow-band correlated-k-based model, which treats soot, H2O, CO2, and CO as radiative species (Eaves et al. 2016; Qiu et al. 2018; Zhang 2009).
Effective green corrosion inhibition of aluminium using analgin in acidic medium: an experimental and theoretical study
Published in Chemical Engineering Communications, 2021
Sumayah Bashir, Hassane Lgaz, Ill-Min Chung, Ashish Kumar
The organic compounds which possess heteroatoms like phosphorous, nitrogen or sulfur are seen to be excellent corrosion inhibitors. The adsorption of these compounds is influenced by the electronic structure of inhibiting molecules, the steric factor, aromaticity, and electron density at the donor site, the presence of functional group such as –CHO, –N = N, R–OH, etc., molecular area, and molecular weight of the inhibitor molecule. The mechanism behind the inhibition process of these compounds is adsorption leading to the protective film formation on metal surface. Gece (2011) concluded that this takes place because of interaction between π-orbital of metals and lone pair. Owing to the hazardous effects of commercially used corrosion inhibitors on environment, it becomes vitally important to replace them with less toxic and eco-friendly corrosion inhibitors (Abdallah et al. 2018). The pharmaceutical compounds are seen to have striking molecular similarities with the commercial corrosion inhibitors besides being environmentally benign. Loto et al. (2012) investigated that drugs typically consist of heterocyclic compounds and carboxylic compounds having cyclic structures which make aromaticity an important parameter to decide the inhibition efficiency of drugs. Some drugs that have been used as corrosion inhibitors of aluminum including the works of Kumar and Karthikeyan (2013) who studied anti-corrosion properties of Amoxyllin. Adejoro et al. (2015) studied ampllicin as corrosion inhibitor. Sumayah Bashir et al. (2019) studied the inhibition efficiency of venlafaxine. Ciprofloxacin was studied as a corrosion inhibitor by Magaji et al. (2012). Dapsone was as corrosion inhibitor studied by Singh et al. (2010). Hameed et al. (2014) Penicillin G showed anti-corrosion properties which was presented by Eddy et al. (2009). The corrosion inhibiting properties of trazodone was studied by Megalai et al. (2013). The corrosion inhibition property of ketamine drug was investigated by Abdallah et al. (2019). The present study depicts theoretical and experimental procedures for anti-corrosion properties of Analgin on Aluminlanium in acidic medium. Also, Quantum-chemical methods have been done which previously proven to be the best and accurate method to illustrate the electronic structure and its reactivity of inhibitor molecule with metallic interface (Abdallah et al. 2019). The molecular structure of Analgin is given below in Figure 1.