Clay is formed by the action of wind and water on rocks over thousands of years. Transcript of radio broadcast:
This is the VOA Special English Development Report.
Clay
Clay is found almost everywhere in the world. It is formed by the action of wind and water on rocks over thousands of years. The rocks change in both chemical and physical ways. Chemically, elements like potassium and aluminum are added and taken away. Physically, the rocks break down into smaller and smaller pieces. After a long time, some of the rock changes to clay.
Clay is important because it is used around the world to make containers of all kinds. Potters add water to soften the clay. This makes it easier to form into shapes by hand or by machine. Then it is fired in an extremely hot stove. The result is a container with a hard surface that will last for many years.
In many countries, clay was formed from volcanoes. This kind of clay usually contains many minerals. So the fires to make containers from volcanic clay must be hotter than those used for non-volcanic clay. The fires may be as hot as one thousand four hundred degrees Celsius.
It is also important to dry the clay containers slowly. This means that the highest temperature should not be reached too fast.
You can add materials to clay to gain desired results. For example, you can add sand to prevent tiny breaks or lines from forming in the finished product. But you should not use sand from the coasts of oceans. Instead, you should use sand from rivers or from other areas of land that are not near the sea.
You can usually find good clay in low areas of islands or land, especially if volcanoes helped form the land. Clay often exists in fields covered with some water. The clay will be found about one meter below the ground. River banks often also have clay about one meter or less under the surface.
You can recognize clay because it is very shiny when it is wet. You can also perform a test. Take some of the material and add enough water to it to make it seem like you are making bread. Then press it in your hand until it is about the size of an egg. It is probably clay if it holds together instead of falling apart when you stop pressing.
And that’s the VOA Special English Development Report, written by Gary Garriott. Guides to working with clay and other materials can be found on the EnterpriseWorks/VITA list of publications. These publications can be ordered for a charge. The list is available at enterpriseworks.org. Transcripts, MP3 and archives of our reports are at voaspecialenglish.com. I’m Chris Cruise.
The disease carried by mosquitoes has been found in Africa and Asia for many years, but appeared in Italy in 2007. People rarely die from it, but the muscle and joint pain can last for weeks or months. Transcript of radio broadcast: 11 April 2009
Correction attachedThis is the VOA Special English Development Report.
People get chikungunya fever when they are bitten by mosquitoes infected with the disease. For many years, the disease has been found in countries in Africa and Asia. The symptoms are increased body temperature, pain in muscles and joints and stomach sickness.
Hospital patients suffering from chikungunya in Ahmadabad, India, in 2006
The disease is not usually deadly. But the muscle and joint pain can last for weeks or months. There is no vaccine to prevent the disease and no special drug to treat it. Doctors advise taking medicines like aspirin or ibuprofen.
The name chikungunya means “that which bends up” in the Swahili language. People infected with the virus walk in a bent-over position because of the severe pain in the joints.
Malaysia reported more than one thousand one hundred cases of chikungunya so far this year. In Indonesia, about two hundred people in central Java became sick from the virus last month. And about one thousand people near Yeshwanthpur in India also showed signs of the disease in March.
But the disease also appeared in a cooler climate in two thousand seven, causing concern about its spread. Italy reported about two hundred cases during warm weather. The medical journal Eurosurveillance Weekly said it was the first time mosquitoes carried the virus inside Europe.
The Aedes aegypti mosquito can carry the chikungunya virus
Two kinds of mosquitoes carry chikungunya fever. One is called Aedes albopictus, or Asian tiger mosquito. It has been reported in many European countries including France, Belgium, Spain and the Netherlands. It also lives in the southern United States. The other mosquito that can carry chikungunya, Aedes aegypti, also is present in the United States.
Ann Powers is an expert on viruses. She works for the Centers for Disease Control and Prevention in Fort Collins, Colorado. She said the disease spread is not directly connected to climate change. But she also said C.D.C. scientists are preparing for possible cases of chikungunya in the United States.
People around the world can prevent diseases spread by mosquitoes by removing standing water from their property. They should try to keep mosquitoes out of their homes. And they should wear clothing that covers the arms and legs when they are outside. DEET and other chemicals that work against insects can keep mosquitoes from biting.
And that’s the VOA Special English Development Report, written by Jerilyn Watson. I’m Steve Ember.
