Principle sedimentation sedimentation (sedimentation size analysis) is based on the particles in the suspension system, the particles themselves neutral (or suffered centrifugal force), suffered buoyancy and viscous resistance of the three balance, and viscous forces obey the principle of Stokes to implement the determination, in which case the particles in the suspension system of the settlement at a constant speed, and the sedimentation rate is proportional to the square of the particle size. Notably, only to meet the following conditions in order to measure the particle size using the sedimentation method; particles should be close to spherical shape wanted, and the liquid was completely wetted; settling velocity of the particles in the suspension system is slow and constant, but reaches a constant velocity time is short; the particles in the suspension system of the Brownian motion does not interfere with its settling velocity; the interaction between particles does not affect the settlement process. Determination of particle size of sedimentation divided into gravity settling and gravity settling two centrifugal sedimentation method, gravity settling adapted particle size of 2 to 100 ?? m particles, and a centrifugal sedimentation method is adapted to a size of 10 ?? m ~ 20 ?? m particles. Due to centrifugal particle analyzer using Stokes principle, so the resulting analysis is an equivalent particle size, particle size distribution for the autumn equivalent weight average particle size distribution. Generally suitable for high-speed centrifugal sedimentation particle size analysis of materials Nali. The method is now more accepted extinction sedimentation method, due to the different particle sizes in the suspension system, different settling velocity, at the same time the depth of particle settling is different angular contact angle of water droplets in Shenzhen factory, so the angle of water droplets tension meter, at different depths density of the suspension will exhibit different variations, according to the measuring beam through an optical density of the suspension system can calculate the particle size distribution. The advantage is to measure the mass distribution. The advantage is a measure of the mass distribution, strong representative test results contrast with the instrument is good, the price is relatively cheap. The disadvantage is that the small particles for test speed slow, poor reproducibility; non-spherical particles of error, it is not suitable for the mixed material, the dynamic range is narrower than the laser diffraction method. Beautiful lotus lightness finds, rolled down from the lotus leaf drops can remove dirt and bacteria on adsorption phenomenon scientists call "self-cleaning effect" or "lotus effect" lotus leaf . 1997 German botanist Professor William Bass Lott inspiration from the successful production of easy-to-clean surface buildings and transportation coatings. Recently, researchers at the University of Michigan through the development of theoretical models, the first successful nano hairy structure and chemical composition and microstructure separated, the essence of the principle of self-cleaning lotus effect research. When a drop of water falls on a lotus leaf, lotus leaf with water drops between the formation of a high degree of contact angle (greater than 90 degrees), so that it gathered into beads without diffusion. Usually drops angle of the surface can test a person's skin with a slight hydrophobicity, the contact angle of about 90 degrees, while the leaves close to the contact angle of water droplets angle of 170 degrees, extremely hydrophobic surface of the leaves. But scientists found that although few actually touching the leaves of the rain droplets fall is not without friction, water droplets away dirt and bacteria on the leaves, and act as a "self-cleaning" function. Scientists for the first time the hairy leaves of the nano-structure and micro-structure and chemical composition separated. They found that, in addition to containing lotus leaf surface wax component, two structures "lotus effect" and the leaves of the related, one is raised micron, one is hairy nanoscale structures. The contact angle of the two structures containing lotus leaf is 142 degrees, the contact angle of the leaves containing only micro structure is 126 degrees, the contact angle of the surface of the wax alone containing only 74 degrees. Scientists believe that hairy nanoscale structure increases the contact angle of 16 degrees, the two structures are the main causes of "lotus effect". "Lotus effect" as a good model that can be used to study many areas, such as lotus effect on the production of coatings can be easy to clean the surface of the house or building, the future lotus effect will have a more broad prospects for development angle of the surface of water droplets can be tested, ShengDing instrument (certified), drop angle provided by the Dongguan Sheng Ding Precision Instrument Company. Dongguan Sheng Ding Precision Instrument Co., Ltd. (www.dgshengding.com) is Dongguan, Guangdong, dedicated instrumentation leader, over the years, the company is implementing the scientific management, innovation and development, the principle of honesty and trustworthiness, and satisfy customer needs. Sheng Ding instrument in leadership with the staff warmly welcome all inquiries negotiations to create ShengDing instrument a better future.