Unsteady mix convectional stagnation point flow of nanofluid over a movable electro-magnetohydrodynamics Riga plate numerical approach.

The flow at a time-independent separable stagnation point on a Riga plate under thermal radiation and electro-magnetohydrodynamic settings is examined in this research. Two distinct base fluids-H2O and C2H6O2 and TiO2 nanostructures develop the nanocomposites. The flow problem incorporates the equations of motion and energy along with a unique model for viscosity and thermal conductivity. Similarity components are then used to reduce these model problem calculations. The Runge Kutta (RK-4) function yields the simulation result, which is displayed in graphical and tabular form. For both involved base fluid theories, the nanofluids flow and thermal profiles relating to the relevant aspects are computed and analyzed. According to the findings of this research, the C2H6O2 model heat exchange rate is significantly higher than the H2O model. As the volume percentage of nanoparticles rises, the velocity field degrades while the temperature distribution improves. Moreover, for greater acceleration parameters, TiO2/ C2H6O2has the highest thermal coefficient whereas TiO2/ H2O has the highest skin friction coefficient. The key observation is that C2H6O2 base nanofluid has a little higher performance than H2O nanofluid.

Femtosecond pulsed laser ablation of polyimide at oblique angles for medical applications.

We report the ablation results for surface modification of polyimide Kapton HN foils using ultrashort femtosecond laser pulses. The modification threshold fluences for 75 µm thick films of polyimide were determined at different incident angles (0°, 20°, 30°, 45°, and 50°) for vertical and horizontal diameters. Ablation at oblique angles was investigated as such interactions are found during laser procedures with the eye that require scanning of the beam and are very important to know for the treatment of various eye diseases. Polyimide, in this study, was considered as a model for corneal sculpting. Use of ultrashort femtosecond laser pulses for high-precision patterning of the sample, without thermal damage to the surroundings, has been investigated. The relationship between the incidence angle with ablation threshold fluence, threshold energy, and beam radius are described. Also, threshold energies and threshold fluences for different thicknesses of polyimide were investigated.

Study of the two-photon excitation of photoinitiator in various solvents, and the two-photon polymerization process.

In this study, the two-photon absorption excited fluorescence of the photosensitizer 4,4'-Bis(diethylamino)benzophenonin in different solvents is investigated by using mode-locked Ti:sapphire excitation having a wavelength of 800 nm with pulse duration of 150 fs at the rate of 1 kHz. The fluorescence signals excited by wavelengths of 800 and 400 nm have been compared. Contribution of these cross-section measurements for the two-photon polymerization processes is also reported.

Determination of two-photon absorption cross sections of photosensitizers and its implications for two-photon polymerization.

We report two-photon absorption cross sections and two-photon excited fluorescence of the photosensitizer 4,4'-Bis(diethylamino)benzophenon and thioxanthone using a femtosecond laser delivering pulses of wavelength 800 nm and 150 fs duration at rates of 1 kHz. Values for the two-photon absorption cross section are derived by comparing the fluorescence signals excited by wavelengths of 800 and 400 nm using a second-harmonic generator. Fluorophore fluorescence intensities dependence with quadratic illumination laser power showed no significant deviation from the two-photon absorption process. Implications of these cross-section measurements for two-photon polymerization are discussed.