The world's second nuclear explosion was achieved with uranium-235. This isotope is unstable and fissions when struck by a neutron. It is, however, found in natural uranium at a concentration of only 0.7 percent. To be useful in nuclear weapons, the concentration must be increased.
Introduction. Influenza, or flu, is a caused by a virus infecting the respiratory system, meaning your nose, throat, bronchial tubes, and lungs. Flu symptoms are usually more severe than those of the common cold and are more likely to affect other parts of your body.
Influenza, commonly known as the flu , is an infectious disease caused by the influenza virus. Symptoms can be mild to severe. The most common symptoms include: a high fever, runny nose, sore throat, muscle pains, headache, coughing, and feeling tired.These symptoms typically begin two days after exposure to the virus and most last less than a week.ymptoms can be mild to severe. The most common symptoms include: a high fever, runny nose, sore throat, muscle pains, headache, coughing, and feeling tired. These symptoms typically begin two days after exposure to the virus and most last less than a week.