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This is a complete list of polychlorinated biphenyl (PCB) congeners. Chemical structure of PCBs. The possible positions of chlorine atoms on the benzene rings are denoted by numbers assigned to the carbon atoms.
The coplanar group members have a fairly rigid structure, with their two phenyl rings in the same plane. It renders their structure similar to polychlorinated dibenzo- p -dioxins (PCDDs) and polychlorinated dibenzofurans , and allows them to act like PCDDs, as an agonist of the aryl hydrocarbon receptor (AhR) in organisms.
A printed circuit board (PCB), also called printed wiring board (PWB), is a laminated sandwich structure of conductive and insulating layers, each with a pattern of traces, planes and other features (similar to wires on a flat surface) etched from one or more sheet layers of copper laminated onto or between sheet layers of a non-conductive ...
There are 209 PCB compounds. Analogously to PCDDs at least two lateral chlorines in each ring in positions 3,4, and/or 5 are needed for dioxin-like activity. Because the AH receptor requires a planar (flat) structure, only PCB congeners that can rotate freely along the C—C axis between the rings can attach the receptor.
Figure 1. A microstrip line shielded by via fences on a printed circuit board. A via fence, also called a picket fence, is a structure used in planar electronic circuit technologies to improve isolation between components that would otherwise be coupled by electromagnetic fields.
In geometry, a convex polyhedron whose faces are regular polygons is known as a Johnson solid, or sometimes as a Johnson–Zalgaller solid [1].Some authors exclude uniform polyhedra (in which all vertices are symmetric to each other) from the definition; uniform polyhedra include Platonic and Archimedean solids as well as prisms and antiprisms. [2]
An RF power amplifier incorporating planar circuit structures. The amplifier on the left feeds its output into a set of planar transmission line filters in the centre. The third circuit block on the right is a circulator to protect the amplifier from accidental reflections of the power back from the antenna
For example, butane has three conformers relating to its two methyl (CH 3) groups: two gauche conformers, which have the methyls ±60° apart and are enantiomeric, and an anti conformer, where the four carbon centres are coplanar and the substituents are 180° apart (refer to free energy diagram of butane).