Speciation can be defined as the distribution of an element among defined chemical species in a system, and speciation analysis as the analytical activities of identifying and/or measuring the quantities of one or more individual chemical species in a sample. 1.3 Structural aspects of speciation: The definitions of species and speciation of elements are based on several different levels of atomic and molecular structure where species differences are manifest.
Noun. 1. rickshaw-a small two-wheeled cart for one passenger; pulled by one person. jinrikisha, ricksha. cart-a heavy open wagon usually having two wheels and drawn by an animal.oun. 1. rickshaw-a small two-wheeled cart for one passenger; pulled by one person. jinrikisha, ricksha. cart-a heavy open wagon usually having two wheels and drawn by an animal.
A pulley is a wheel on an axle or shaft that is designed to support movement and change of direction of a taut cable or belt, or transfer of power between the shaft and cable or belt. In the case of a pulley supported by a frame or shell which does not transfer power to a shaft, but is used to guide the cable or exert a force, the supporting shell is called a block, and the pulley may be called a sheave. A pulley may have a groove or grooves between flanges around its circumference to locate the cable or belt. The drive element of a pulley system can be a rope, cable, belt, or chain. Hero of Alexandria identified the pulley as one of six simple machines used to lift weights.