The mechanical properties of a material are those properties that involve a reaction to an applied load. The mechanical properties of metal determine the range of usefulness of a material and establish the service life that can be expected. Mechanical properties also used to help classify and identify material. The most common properties considered are: Strength The general ability of a material to withstand an applied force. Hardness Hardness is a measure of how easily a material can be scratched or indented. Hard materials are often also very brittle – this means they have a low resistance to impact. Well Known hard materials include diamond and hardened high carbon steels. Brittleness A material that has tendency to break easily or suddenly without any extension first. Good examples are Cast iron, Concrete, High carbon steels, Ceramics, and some polymers such as Urea formaldehyde (UF). Toughness A material that absorbs impact (sudden forces ...
A coffee patron or coffee lover looking for the best coffee in the world? Just as there are wine tasters who can grade a wine, similarly there are some coffee experts who can name some of the best coffee brands in the world. If you want to know where does the world's best coffee come from, then read on. Coffee is ground coffee beans brewed into a caffeine drink that has become more like water for many parched souls looking for some instant energy. Many begin their day with the fresh, crisp and natural flavor of coffee and end their day's work with the same. For many drinking coffee is like an experience, to savor the aroma, the flavor and to feel the warm cuppa flowing down gently through their throat. Coffee is basically a bean grown in more than 70 countries around the world and many countries have the major chunk of their economies based on coffee export. Coffee needs specific conditions to grow and produce the best coffee in the world. Legends of the World's...
Alkynes in nature and medicine According to Ferdinand Bohlmann, the first naturally occurring acetylenic compound, dehydromatricaria ester, was isolated from an Artemisia species in 1826 . Polyynes, a subset of this class of natural products, have been isolated from a wide variety of plant species, cultures of higher fungi, bacteria, marine sponges, and corals. Some acids like tariric acid contains an alkyne group. Diynes and triynes, species with the linkage RC ≡ C-C ≡ CR' and RC ≡ C-C ≡ C-C ≡ CR' respectively, occur in certain plants ( Ichthyothere , Chrysanthemum , Cicuta , Oenanthe and other members of the Asteraceae and Apiaceae families). Some examples are cicutoxin , oenanthotoxin , falcarinol and carotatoxin . These compounds are highly bioactive, e.g. as nematocides . 1-Phenylhepta-1,3,5-triyne is illustrative of a naturally occurring triyne. Alkynes occ...
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