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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.
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.
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).
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 ...
3D image of an iridium diphosphine pincer complex.. In chemistry, a transition metal pincer complex is a type of coordination complex with a pincer ligand. Pincer ligands are chelating agents that binds tightly to three adjacent coplanar sites in a meridional configuration.
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.
SIWs are promising structures that can be used in complex microwave systems as interconnects, filters, etc. However, a problem may arise: the connection of the SIWs with other kinds of transmission lines (TL), mainly microstrip, coplanar and coaxial cable. The goal of such transitions between two different topologies of TL is to excite the ...