Double-contrast barium enema Double-contrast barium enema A double-contrast barium enema is a form of contrast radiography in which x-rays of the colon and rectum are taken using two forms of contrast to make the structures easier to see. A liquid containing barium (that is, a radiocontrast agent) is put into the rectum. Barium is a silver-white metallic compound that outlines the colon and rectum on an x-ray and helps show abnormalities. Air is also put into the rectum and colon to further enhance the x-ray. Double-contrast barium enemas are less invasive than a colonoscopy and have comparatively fewer issues in a viable large
Nickel silver (Shadow model); these are far rarer than traditional lacquered brass saxophones. Student-level flutes and piccolos are also made of silver-plated nickel silver, although upper-level models are likely to use sterling silver. Nickel silver produes a bright and powerful sound quality; an additional benefit is that the metal is harder and has more corrosion resistance than brass. Because of its hardness, it is the most commonly used material for woodwind keys. Most clarinets, flutes, oboes and similar wind instruments have nickel silver keys, normally silver-plated. It is used to produce the tubes (called staples) onto which oboe reeds are tied. Many