56 research outputs found

    Evaluation of Important Treatment Parameters in Supraphysiological Thermal Therapy of Human Liver Cancer HepG2 Cells

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    This study was aimed at simulating the effect of various treatment parameters like heating rate (HR), peak temperature (PT) and hold/total treatment time on the viability of human liver cancer HepG2 cells subjected to different thermal therapy conditions. The problem was approached by investigating the injury kinetics obtained using experimentally measured viability of the cells, heated to temperatures of 50–70°C for 0–9 min at HRs of 100, 200, 300 and 525°C min(−1). An empirical expression obtained between the activation energy (E) and HR was extended to obtain the E values over a broad range of HRs from 5 to 600°C min(−1) that mimic the actual conditions encountered in a typical thermal therapy protocol. Further, the effect of the HR (5–600°C min(−1)) and PT (50–85°C) on the cell survival was studied over a range of hold times. A significant drop in survival from 90% to 0% with the simultaneous increase in HR and PT was observed as the hold time increased from 0 to 5 min. For complete cell death, the hold time increased with the increase in the HR for a given PT, while the total time showed presence of minima for 60, 65 and 70°C at HRs of 50, 100 and 200°C min(−1), respectively

    Creation of 3-dimensional carbon nanostructures from UV irradiation of carbon dioxide at room temperature

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    A method is presented for the production of carbon nanomaterials from carbon dioxide in a low temperature process. In this method, carbon dioxide is irradiated with an ultraviolet laser at the conditions of critical opalescence where light is scattered and absorbed. Spherical carbon nanoparticles are obtained under these conditions on metal substrates without any additional catalyst near room temperature. The particles are of approximately uniform shape and size of around 100 nm. Some of the particles form clusters. The method is reproducible on different substrates. Quantum chemical calculations have been employed in order to elucidate the role of critical opalescence and of the substrate. The calculations show that the presence of molecular clusters at the critical point is essential in decreasing the excitation energy. The dissociation reaction most likely occurs on the surface of the substrate, where the excitation energy is decreased even further
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