15 résultats pour "aluminum"

• Aluminum - chemistry.

• Bicycle.

  narrow as possible to minimize weight and interference with pedaling. F Specialty Bicycles Many other types of bicycles are designed for special purposes. Although not as common as standard single-rider racing, touring, mountain, or recreational bicycles,they nonetheless have significant niches. Recumbent bicycles are bicycles on which the rider sits upright as if in a chair, with legs and feet stretched out in front. Because they support the rider’s lower back,recumbents allow the rider far mo...

• Airplane.

  For example, the Anglo-French Concorde, a commercial supersonic aircraft, was generally limited to over-water routes, or to those over sparsely populated regions ofthe world. This limitation impacted the commercial viability of the Concorde, which ended its regular passenger service in October 2003. Designers today believe theycan help lessen the impact of sonic booms created by supersonic airliners but probably cannot eliminate them. One of the most difficult practical barriers to supersonic fl...

• Gemstones.

  In the late 1960s a method was developed for “growing” diamonds by heating a diamond particle to a high temperature and subjecting it to methane gas. The gasdecomposes into carbon atoms, which adhere to the diamond crystal. The crystal structure of the enlarged diamond is identical to that of a natural diamond. Diamondsof about 1 carat (200 mg or 0.007 oz) have been produced by this method, but their cost is still considerably higher than that of naturally occurring diamonds. Sapphires are made...

• Suriname (country) - country.

  Tongo, a Creole language. Also known as Taki-Taki, Sranang Tongo includes elements of several languages and is the vehicle for most interethnic communication. Otherlanguages spoken in Suriname include Hindi, Javanese, Chinese, English, and French. Small numbers of Native Americans still speak indigenous languages. The main religions in Suriname are Christianity, Islam, and Hinduism. The majority of Christians are Roman Catholics, and members of the Moravian Church predominateamong Protestants. E...

• Space Shuttle - astronomy.

  The two SRBs, with their combined thrust of some 26 million newtons (about 5.8 million lb), provide most of the power for the first two minutes of flight. The SRBs takethe space shuttle to an altitude of 45 km (28 mi) and a speed of 4,973 km/h (3,094 mph) before they separate and fall back into the ocean to be retrieved,refurbished, and prepared for another flight. After the boosters fall away, the three main engines continue to provide thrust. These engines are clustered at the rear end of the...

• Bahrain - country.

  A Religion Almost all Bahrainis and the majority of nonnatives are followers of Islam (Muslims). About 70 percent of all native Bahrainis belong to the Shia branch of Islam, whilethe remainder, including the ruling al-Khalifa clan, are adherents of the Sunni branch. Non-Muslims, including Hindus, Buddhists, Christians, and Jews, account for 15percent of the total population. High unemployment among the Shia population has caused considerable discontent on the part of this group toward the Sunni...

• Iceland - country.

  III PEOPLE Icelanders are one of the most homogenous peoples in the world. They are predominantly of Nordic origin, descendants of the hardy people who emigrated fromNorway to Iceland in the Middle Ages. There are also some Celtic influences from Irish and Scottish immigrants who arrived from the British Isles ( see Celts). The population of Iceland (2008 estimate) is 304,367. Numerous times in its history, Iceland has suffered major population losses due to epidemics, volcanic eruptions, and...

• Air - chemistry.

  lighting systems, fertilizers, and semiconductors (substances used to make the chips in computers, calculators, televisions, microwave ovens, and many other electronicdevices). A Oxygen More than half of the oxygen produced in the United States is used by the steel industry, which injects the gas into basic oxygen furnaces to heat and produce steel(see Iron and Steel Manufacture: Basic Oxygen Process ). Metalworkers also combine oxygen with acetylene to produce high-temperature torch flames th...

• Cameroon - country.

  seminomadic herders of the north. Cattle, goats, and fowl are the most commonly raised animals. B Forestry and Fishing Timber is traditionally one of Cameroon’s most valuable exports, consisting mainly of mahogany, ebony, and teak. The timber cut in 2006 amounted to 11.4 million cu m(401 million cu ft). Most of the fish caught in Cameroon come from the country’s rivers and lakes and are consumed locally. However, deep-sea fishing activity isincreasing, especially from the port of Douala. Some 1...

• Pittsburgh - geography.

  College of Allegheny County (1966), with branches in the city and suburbs. Pittsburgh has many outstanding cultural institutions. The Oakland district is where Carnegie Mellon University and the University of Pittsburgh are located. The CarnegieMuseums of Pittsburgh include The Carnegie Museum of Art (including the Scaife Galleries), which holds a distinguished motion-picture and video collection and a uniquestudy of architecture; the Carnegie Museum of Natural History, which displays an extensi...

• Mountain Climbing.

  teeth on one side, and a straight, flat, metal blade called an adze on the other. Ice axes have many uses. One of the most common is to help the climber stay balanced on steep slopes. The climber swings the axe with a short, quick movement to lodge the pick in snow or ice, creating a secure anchor. If a climber should slip and beginsliding down a snowfield, a self-arrest can be performed by turning face down on the snow and burying the pick in the snow surface. The climber’s weight over the...

• Soil. I INTRODUCTION Soil, the loose material that covers the land surfaces of

  an exchange between plants and the atmosphere, as oxygen diffuses into the soil and is used by roots for respiration. In turn, the resulting carbon dioxide diffusesthrough pore spaces and returns to the atmosphere. This exchange is most efficient in soils with a high degree of porosity. For farmers, gardeners, landscapers, andothers with a professional interest in soil health, the process of aeration—making holes in the soil surface to permit the exchange of air—is a crucial activity. Theburrowi...

• Alzheimer's Disease.

  compared residents of Ibadan, Nigeria, who eat a mostly low-fat vegetarian diet, with African Americans living in Indianapolis, Indiana, whose diet included a variety ofhigh-fat foods. The Nigerians were less likely to develop Alzheimer’s disease compared to their U.S. counterparts. Some researchers suspect that health problems suchas high blood pressure, atherosclerosis (arteries clogged by fatty deposits), high cholesterol levels, or other cardiovascular problems may play a role in the devel...

• Badminton.

  Once play has started, players tend to hit straight, low-flying shots called drives. When the shuttle remains close to the center of the court, net shots can be a goodoption. Net shots can be hard-hit or delicate. They are aimed at the front area of the opponent’s court, forcing the opponent to play the shot close to the net. If the opponent manages to return a net shot, the return must be hit high to clear the net. This gives the player a chance for a smash—the deadliest attacking stroke inbadm...