An average of 65 percent of children aged between 8 and 11 have their own smartphone in the U.K. according to a survey by Internet Matters. That survey also found that the majority of parents would like a minimum age for smartphone ownership in the U.K. to be set at age 10. However, some kids are using smartphones from a very young age. One study by the American Academy of Pediatrics that focused on children in an urban, low-income, minority community suggested that almost all children (96.6 percent) use mobile devices and that 75 percent have their own mobile device by the age of four.
A cyclic acetal is an acetal in which the acetal carbon and one or both oxygen atoms are members of a ring. An acetal is a compound that contains two ether groups on the same carbon atom. If the two OH groups are part of a 1,2- or a 1,3-diol, the product is a cyclic acetal. The video below describes how a cyclic acetal is formed from a diol. The purple #color(purple)(O)# atom in the hemiacetal intermediate is held close to the hemiacetal carbon, so the intramolecular ring-closing reaction is fast.
Acetal Copolymer for Biodiesel Fuel Systems. Acetal, PBT, and nylon, the most common choices, create gear sets having good fatigue and wear resistance, lubricity, rigidity for high tangential forces, and toughness in shock-loaded situations such as in reciprocating motors.