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Kilovoltage X-Ray Units
Published in W. P. M. Mayles, A. E. Nahum, J.-C. Rosenwald, Handbook of Radiotherapy Physics, 2021
The requirement for tube cooling results from the inefficiency of x-ray production in the kilovoltage energy range, with about 99% of the energy of the electrons striking the target being dissipated as heat. Heat is conducted through the target into the copper anode block and, in the case of the metal–ceramic tube, efficiently removed by direct water (or oil) cooling of the copper block. Some units may also incorporate secondary cooling of the pumped coolant using a remote heat exchanger. Interlocks prevent the beam from running if the coolant temperature gets too high or if its flow rate drops below an acceptable level.
Monographs of fragrance chemicals and extracts that have caused contact allergy / allergic contact dermatitis
Published in Anton C. de Groot, Monographs in Contact Allergy, 2021
A male patient had a 3-year history of dermatitis of his hands, forearms and face. He had worked as an engineer grinding components for printing presses for 24 years. During an enforced absence from work, he noticed that his rash resolved, but relapsed within 2 days. When the coolant used during the grinding process was withdrawn, the patient’s rash subsequently resolved and he has remained symptom-free ever since. Patch testing gave positive reactions to the coolant at 10% aq., fragrance mix, Myroxylon pereirae resin, diethanolamine, oakmoss absolute and his own soluble oil. Further patch tests were then carried out with the constituents of the coolant plus the individual components of the fragrance used within it, which yielded positive reactions to oakmoss resin and monoethanol-amine (63).
Effects of Environmental Factors on the Endocrine System
Published in George H. Gass, Harold M. Kaplan, Handbook of Endocrinology, 2020
Ethylene glycol ethers are commonly used as antifreeze in automobile coolant. They have been shown to induce testicular degeneration in rats, but there has been no documented reproductive toxicity in humans. Toluene is a common solvent in paints. Some women exposed to toluene occupationally suffer from menstrual disorders. In pregnant women, there is a decrease in fetal growth and newborn weight among those exposed to toluene which is embryotoxic rather than teratogenic.
System for delivering microwave ablation to subcutaneous tumors in small-animals under high-field MRI thermometry guidance
Published in International Journal of Hyperthermia, 2022
Jan Sebek, Tej B. Shrestha, Matthew T. Basel, Faraz Chamani, Nooshin Zeinali, Ivina Mali, Macy Payne, Sarah A. Timmerman, Pegah Faridi, Marla Pyle, Martin O’Halloran, M. Conall Dennedy, Stefan H. Bossmann, Punit Prakash
We investigated the feasibility of delivering microwave ablation to subcutaneously implanted experimental tumors in small-animals using a water-cooled microwave applicator previously developed for mild-hyperthermia applications [15, 31]. The applicator was designed to radiate 2.45 GHz microwave power to sub-cutaneous targets, while positioned externally adjacent to the targeted tumor. The applicator consists of an ‘S’ shaped radiating element tuned to operate at 2.45 GHz terminating a feeding coaxial transmission line. To direct the radiation toward the tumor, the antenna is coupled with a hemi-cylindrical copper reflector. Cooling water is circulated through the reflector tube, which returns through an outer polyimide sheath, thus providing a closed-loop coolant flow circuit. The applicator was designed to be ∼70 cm in length to allow for insertion within the vertical high-field scanner. Based on the estimated insertion loss of the coaxial cable (UT47C, Microstock Inc.) at 2.45 GHz, and the cable length of approximately 70 cm, we estimate approximately 72% power applied at the connector of the applicator is transferred to the antenna and radiated into the tissue. Considering 6 ft long RG400 cable between power meter and applicator, it is estimated that approximately 53% of power measured at the power meter is transferred into the tissue. Figure 2 illustrates the applicator geometry and depicts a fabricated antenna.
Composition of aerosols from thermal degradation of flavors used in ENDS and tobacco products
Published in Inhalation Toxicology, 2022
Philip J. Kuehl, Jacob D. McDonald, Derek T. Weber, Andrey Khlystov, Matthew A. Nystoriak, Daniel J. Conklin
Nonetheless, these degradation aerosol mixtures can be used in an in vitro toxicity study to evaluate and screen for the potential impact of these products created under extreme degradation conditions. In fact, in one such study, the high temperature atmosphere mixture from parent cinnamaldehyde is less toxic than the parent compound in human induced pluripotent stem cells differentiated into cardiomyocytes (hiPSC-CM) (Nystoriak et al. 2019), which is not surprising given the high toxicity of concentrated cinnamaldehyde as present in some e-liquids (Clapp et al. 2017, 2019). Of particular concern is that each heated flavorant atmosphere contained abundant menthol. Menthol has coolant properties that mask the effects of irritants in tobacco smoke, and thereby, it promotes both deeper inhalation, greater acquisition of nicotine, and thus, more rapid addiction (Willis et al. 2011; Ha et al. 2015). Thus, menthol has been long used in combustible cigarettes to market cigarettes to communities of color to promote greater smoking. Thus, inclusion of any one of these four flavorants tested here (and perhaps other flavorants, e.g. ethylvanillin) may be one way that tobacco industry promotes addiction with e-cigarettes. Notably, FDA did not ban menthol flavoring from e-liquids although fruit, candy and other characterizing flavors were banned. (FDA News Release FDA 2020).
Predicting tubular heat exchanger efficiency reduction caused by marine biofilm adhesion using CFD simulations
Published in Biofouling, 2022
David Boullosa-Falces, David S. Sanz, Sergio Garcia, Laura Trueba-Castañeda, Alfredo Trueba
The validation of the CFD biofilm model is essential to ensure the accurate behaviour of the model under the different working conditions of heat exchanger systems using seawater as a coolant. In the above-mentioned simulations, it was assumed that the surface algorithm controls the heat transfer owing to biofilm adhesion. The CFD simulation results reveal the temperature distribution over the surface in the 3D geometry, which significantly varied during the experiment. The surface temperature profiles of the heat-exchanger tube are shown in Figure 7. The tube-side seawater flow lost heat to the shell-side water flow as the biofilm adhesion increased during the simulation. Furthermore, the tube-side seawater flow lost heat from the shell-side water flow as the FVS increased. The temperature of the shell-side seawater flow wall decreased as the biofilm adhesion increased. Additionally, Figure 7 shows that the seawater flow temperature at 3 m s−1 was lower than that at 1 m s−1; therefore, the worst operating condition of the exchanger tube occurred on day 60 at 3 m s−1. These results are in good agreement with those obtained by previous studies (Trueba et al. 2015; Boullosa-Falces et al. 2021). The increase in the FVS observed in the CFD biofilm model had a notable effect on the heat transfer owing to the reduction of biofilm adhesion.