62 research outputs found
Nanobubbles in Ultrapure Water Can Self‐Propel
No full textNanobubbles are sub- micron-sized gas entities that find applications in a wide range of scientific fields. Typically, they are thought to diffuse according to Brownian motion. We report the existence of self-propelled motion of oxygen bulk nanobubbles in ultrapure water at body temperature. Their motion, to a large extent, is self-affine; there are different scaling exponents along the x- and y-axes as well as for the lateral displacement. We use fractal analysis, and we calculate the structure function, the normalised velocity autocorrelation function, the skewness, and the kurtosis. All descriptors attest the existence of a quasi-Gaussian stochastic process, which is classified as fractional Brownian motion. More than 50 % of the trajectories along the x-axis follow superdiffusion, while this amount drops to 30 % for motion along the y-axis as a result of the asymmetry of the field of view
Kinetic Theory
No full textThe world is governed by motions. The term kinetics partially originated from the Greek word "kinisis," which means motion. How important is motion in our life is easily understood. But, how the kinetic theories have been developed during years? Which are the new kinetic theories and updates in recent years? This question and many others can be answered with this book. Some important areas discussed in this book are the kinetic theory of gases, kinetic theory of liquids and vapors, thermodynamic aspects, transportation phenomena, adsorption-kinetic theories, linear and nonlinear kinetic equations, quantum kinetic theory, kinetic theory of nucleation, plasma kinetic theory, and relativistic kinetic theory
From Bubbles to Nanobubbles
No full textNanobubbles are classified into surface and bulk. The main difference between them is that the former is immobile, whereas the latter is mobile. The existence of sNBs has already been proven by atomic force microscopy, but the existence of bNBs is still open to discussion; there are strong indications, however, of its existence. The longevity of NBs is a long-standing problem. Theories as to the stability of sNBs reside on their immobile nature, whereas for bNBs, the landscape is not clear at the moment. In this preliminary communication, we explore the possibility of stabilizing a bNB by Brownian motion. It is shown that a fractal walk under specific conditions may leave the size of the bubble invariant
Waste Marble Slurry as Partial Substitution for Cement: Effect of Water-to-Cement Ratio
No full textThis study investigates the potential of waste marble slurry as a partial replacement for ordinary Portland cement, with particular emphases on the influence of the water-to-cement (w/c) ratio and the objectives of determining the effect of water content and the optimum marble slurry concentration. Cement pastes were prepared with three w/c ratios (0.3, 0.4, and 0.5) and five substitution levels of marble slurry (0%, 5%, 10%, 15%, and 20%). Workability was assessed through mini slump flow tests, while mechanical performance was evaluated via compressive and flexural mechanical tests. The initial and final setting times were also investigated. Electrical resistivity measurements, combined with X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM), were used to examine chemical composition and microstructure. Results showed that marble slurry behaves as an inert filler, rather than a reactive component. Its incorporation, up to 10%, significantly improves the fresh properties and mechanical performance of mixes with higher w/c ratios (0.4 and 0.5). At lower w/c ratios (0.3), strength was adversely affected due to insufficient hydration. Electrical resistivity measurements indicated that pastes with w/c = 0.5 and up to 10% slurry replacement became slightly more resistant to electrical current, whereas mixes with lower w/c ratios (0.3 and 0.4) showed only minor reductions at 5% and 10% cement substitution. SEM imaging demonstrated a denser microstructure when marble slurry was incorporated, consistent with a filler effect. Marble slurry was also found to accelerate the setting of cement pastes, an effect most evident at lower w/c ratios and higher substitution levels. Overall, the findings highlight that waste marble slurry can be effectively utilized at moderate replacement levels in cement-based materials, contributing to sustainable construction practices by reducing cement consumption and marble waste disposal
Polymeric Materials for Water and Wastewater Management
No full textWater is a crucial point of interest nowadays due to its special management [...
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