About 22% of the energy used in the U.S. comes from natural gas. There are about 300,000 miles of natural gas pipelines in the lower 48 states and 425,000 gas producing wells. The history of natural gas.
thru-hole. A circuit board packaging technique in which the leads (pins) on discrete components and chips are inserted through holes in the printed circuit board and soldered from beneath.
A hole in the septum between the heart's two upper chambers is called an atrial septal defect (ASD). A hole in the septum between the heart's two lower chambers is called a ventricular septal defect (VSD). ASDs and VSDs allow blood to pass from the left side of the heart to the right side.n atrial septal defect (ASD) is a hole in the part of the septum that separates the atria (the upper chambers of the heart). This hole allows oxygen-rich blood from the left atrium to flow into the right atrium instead of flowing into the left ventricle as it should.