Self-buckling is an interesting phenomenon that is easily found around us, either in nature or in objects made by human. Palm fronds which initially directed upward when they were short and turned into bending after appreciably longer is an example of the self-buckling phenomenon. We report here that the self-buckling of columns can be treated as a process of second-order phase transition by considering the straight column as "disorder state", the bending column as "order state", and the temperature as the inverse of column length. The "critical temperature" corresponds to the inverse of critical length for buckling, 1/L cr , and the deviation angle made by column free end relative to vertical direction satisfies a scaling relationship with a scaling power of 0.485. Changing of the column geometry from the vertically upward to the bending state can be considered as a transition from disorder state to order state.

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The present work focused on the effects of TiO2 in degrading organic wastewater. Technical TiO2 of anatase crystalline phase was used. TiO2 photocatalyst showed a powerful result in destroying organic effluent. Spray coating was conducted to immobilize the TiO2 particles onto the plastic buffer followed with heat-treatment process. As a result, 30 mL of 25 mg L−1 methylene blue (MB) used in the photocatalyst test was sucessfully degraded after 4 hours of irradiation. Repetitive use of the TiO2 films still has a great photodecomposition ability of removing 99% of the organic contaminant after 5 times use.

Rice winnowing is a process of separation of small and large rice grains by air flow practiced since the ancient human history especially in societies where rice is the main source of carbohydrate (in Asia, Africa, and Latin America). Indeed, this process contains rich of scientific rule but has never been documented by the old society. We report here experimental investigation of the rice winnowing and develop a physical model to explain the process of segregation of rice grains having different size or density. Flapping the tray in the winnowing process, generates a vortex centered at position around the tray free end. We demonstrated numerically that the effectiveness of segregation is strongly depended on the different in grain sizes (for grain from the same material), the initial position of the grain, and the angular velocity of the vortex generated by flapping the tray. We obtained a phase diagram describing different final conditions of winnowing process (either the small grains move towards the tray fee end or move toward the inner end of the tray, able or unable to leave the tray at the free end). The result can be useful to design a new method in separating grains based on size or density.