ScienceIQ.com

Potassium Iodide To The Rescue

Since the end of the Cold War, the focus of the nuclear threat has changed from hostile countries to terrorist cells. What should we do if terrorists set off a dirty bomb in a populated area, or sabotage a nuclear power plant? Some say the first thing we should do is grab a bottle of potassium iodide (KI). But that depends. First, about the KI. ...

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PotassiumIodide
Astronomy

Uncharted Meteors

In 1967, NASA's Mariner 4 spacecraft was cruising through the solar system, not far from Earth, when something unexpected happened. 'Mariner 4 ran into a cloud of space dust,' says Bill Cooke of the ... Continue reading

UnmappedMeteors
Biology

How Biological Clocks Work

Anyone who has traveled has experienced jet lag—that groggy realization that while your day is beginning in Washington, DC, the night you just left in San Francisco is hardly over. Jet lag is an ... Continue reading

HowBiologicalClocksWork
Geology

All That Glitters

Gold is called a 'noble' metal because it does not oxidize under ordinary conditions. Its chemical symbol Au is derived from the Latin word 'aurum.' In pure form gold has a metallic luster and is sun ... Continue reading

AllThatGlitters
Geology

What Are The Dangers Of Lightning?

Lightning is the underrated killer. In the United States, there are an estimated 25 million cloud-to-ground lightning flashes each year. While lightning can be fascinating to watch, it is also ... Continue reading

DangersOfLightning

What Are Composite Materials?

CompositeMaterialsA composite material is one in which two or more separate materials have been combined to make a single construct having more desirable properties. What many people don't realize is that composites are probably the most common structural materials in the world, and have always been an essential part of their lives. Concrete, paper, corrugated cardboard, plywood, fiberglass, bamboo, cornstalks, trees, bricks... all are composite materials. Far from being a new invention, composite materials are the main structural elements of nature. Take a close look at the grain and structure of a piece of wood, and you will see how its strength comes from a structure of fibers bound together side by side.

Man's first use of such composite materials was probably the adobe brick. Mud or clay can be shaped and dried into a hard block, but that kind of block has little load bearing strength and can be easily crushed by the weight of other blocks on top of it. At some point in time, it was found that mixing dried grass or straw into the mud produced a brick with superior properties, a brick that could bear much greater loads without being crushed than a brick of plain dried mud could bear.

Plywood is another example. In plywood, thin sheets, or 'plies' of wood are laminated together. In each ply, the wood fibers runs in one particular direction, and each ply is aligned in a different direction than the adjacent plies. This gives the resulting stack of wood plies an optimum strength in all directions, making plywood a very versatile and useful structural material. A third example of a composite material is reinforced concrete, used in the construction of bridges and buildings. Steel rods are encased in a matrix of concrete, producing reinforced concrete, which has much better strength and load-bearing properties than concrete that has not been reinforced.