Investigations on mechanical properties of biological cells especially cancer cells can considerably help recognizing various types of cancers. In this paper, we have concentrated on finding mechanical properties of breast cancer cell (MCF-7), elastic and viscoelastic, using atomic force microscopy. Initially, topography and apparent properties of the MCF-7 cell are studied, then the results are analyzed and compared with the literature to ensure the validity. After accurate diagnosis of MCF-7 cells, force-indentation curves for thirty-one cells, each in three different points, are obtained and the elasticity module of each point is calculated using Hertz and Dimitriadis theories. To ensure about the accuracy of experimental data, some statistical analysis is done to extract distribution functions for elasticity module of each theory. Due to the importance of adhesion force in the friction force, the purpose of this section is to determine adhesion changes in different points of the cell. In the next step, spring and viscosity force gradients and consequently stiffness and viscosity in different indentation depths are measured and finally appropriate creep function is extracted for viscoelastic behavior of MCF-7 using the Kelvin-Voigt model.

In this work, the CO 2 absorption by potassium hydroxide aqueous solution was studied. The response surface methodology (RSM) based on central composite design (CCD) was used to design experiments, make models, and find the optimum operating conditions for attaining desirable responses in the range of temperature, pressure and absorbent concentration of 25-65 °C, 2-10 bar and 0.01-1.21 mol/lit, respectively. The effects of process variables and their interactions on the responses were investigated with the numerical model, obtained from experimental data fitting to a second-order polynomial model, to achieve the optimal conditions. The experiments and numerical model indicated that the increase in temperature and absorbent concentration decrease CO 2 loading, and an increase in pressure increase CO 2 loading. Optimum conditions were found to be the temperature of 35 °C, pressures of 4 bar and, KOH concentration of 0.412 mol/lit. The CO 2 loading of 0.745 and CO 2 removal efficiency of 32.221% were achieved in the optimal conditions. The modified Pitzer's G E model was used for CO 2 + KOH + H 2 O system, in order to investigate the species concentration in the liquid phase. The average relative error between predicted CO 2 loading and experimental CO 2 loading was 7.4%.

Application of four nano-contact mechanics models, JKR, DMT, Hertz and PT in manipulation of biological cells in biological environment based on atomic force microscope has been analyzed, and the sensitive and non-sensitive parameters and their sensitive ranges have been identified. To analyze sensitivity of contact theories to basic parameters of biological cell, the Sobol method was used. All the used models are small deformation contact mechanics models, but they are different in considerations and limitations. This selection was on purpose to analyze and compare theoretical and empirical models sensitivities. The results indicate that the deformation of biological nano-particle is very sensitive to the elasticity modulus in all models. Adhesion energy, Poisson ratio and particle radius have, respectively, the next ranks which the results of graphic SA confirm, but their effects are not the same in different models. Moreover, the results of the graphic sensitivity analysis SA show that the degree of sensitivity depends on the apparent values of input parameters, such that by changing the magnitude of a specific parameter, it could be possible to increase or decrease the sensitivity.

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This work incorporates experimental methods based on Atomic Force Microscopy (AFM) in order to extract the physical and mechanical characteristics of the head and neck cancer (HN-5) cell line such as cell topography, modulus of elasticity and viscoelastic properties. The initial parameters to determine the mechanical properties are obtained by extracting information from cantilever's force-displacement curve and vertical and horizontal displacement. Next, the changes in elasticity modulus at different points in the cell are attained using the experimental results, followed by studying the differences of these properties at various spots of the cell. Furthermore, cellular folding factor is calculated as a significant property in diagnosing the extent of cancer progression. Moreover, parameters such as adhesion and intermolecular forces are measured which are involved in the first phase of manipulation and during the application of the cantilever force to the particle. Finally, after calculating the indentation depth and contact radius using contact theories, critical manipulation time and force are obtained. Through modeling the cell, the creep function, the spring constant and the damping coefficient corresponding to the cell, are also extracted.