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.
The flu is a respiratory illness caused by the influenza virus. The flu is not the same as a cold, although they share many of the same symptoms.The cold is caused by a different virus, and it tends to have milder symptoms than the flu.Colds are also less likely to cause serious complications.When the influenza virus gets into the body, it moves into the respiratory tract.he flu is not the same as a cold, although they share many of the same symptoms. The cold is caused by a different virus, and it tends to have milder symptoms than the flu. Colds are also less likely to cause serious complications. When the influenza virus gets into the body, it moves into the respiratory tract.