.... Geoff Ballard and a small team of physicists were able to develop the Proton Exchange Membrane (PEM) to produce nearly ten times as much energy, while being only a fraction of the size. How the PEM Works: A is an electrochemical device that produces electricity silently, without combustion. Hydrogen fuel, which is one of the most abundant chemicals in the universe, and oxygen from the air are electrochemically combined in the to produce electricity. Heat and pure water vapour are the only by-products of the . The Ballard Fuel Cell is made up of two electrodes, the anode and the cathode, separated by a polymer membrane electrolyte. Both the ano .....

.... genome has four genes: pol, env, pre-core and X that respectively encode the viral DNA-polymerase, envelope protein, pre-core protein (which is processed to viral capsid) and protein X. The function of protein X is not clear but it may be involved in the activation of host cell genes and the development of cancer. Hepatitis B is a serious public health problem that affects people of all ages in the United States and around the world. Each year, more than 240,000 people contract hepatitis B in the United States. A highly infectious virus that attacks the liver causes the disease. (HBV) infection can lead to severe illness, liver damage, and, in some .....

.... such as TNT . During the World War 2 in 1945, the first Atomic Bomb blast on Hiroshima, Japan, obliterated three-fifth of the city within seconds and killed a total of 115,000 people in only a few minutes according to a local newspaper in Japan. Moreover, the second bomb being dropped at Nagasaki killed an average of 70,000 people. In these two blasts, entire families perished, leaving no one to report the death until four months from the catastrophe. This has made the Atomic Bomb the most powerful weapon ever invented in mankind. Secondly, countries that produce these bombs are harming others as well as themselves if there was wa .....

.... night, the solar energy, which is stored as vast quantities of heat in city buildings and roads, is released slowly into the city. The dissipation of heat energy is slowed and even stopped by the tall building walls that do not allow infrared radiation to escape as readily as do the relative level surfaces of the surrounding countryside. The slow release of heat tends to keep city temperatures higher than those of the unpaved faster cooling areas. On clear, still nights when the heat island is pronounced, a small thermal low- pressure area forms over the city. Sometimes a light breeze, called a country breeze which blows from the countryside in .....

.... with a friend of his with a single line , but later when he wanted to talk to another friend of his he needed to use another line to connect his phone and the phone of his friend . So imagine that he has X friends , he would need X(X-1)/2 lines and X-1 phones , that was impossible so the need of networks come up . The network first developed for the need of the voice communication but after the appearance of data communications need the same network was used . From the time that electricity and electronics had developed there was rapidly changes at the section of the communications . After the decade of the 1950 the computers started developing .....

.... or liquids. When fuels combine with oxygen from the air, they release their stored energy as heat. We recognize this process as burning. The individual relies on food for fuel which contains energy-giving substances that our bodies can store until we need this energy to use our muscles. When we do use our muscles within us, we may not always be sure that heat is given off. Our bodies do not burst into flames but the perspiration on our skin is a clue to what is happening. The movement of the windsurfer has a different explanation. The windsurfer is propelled along by a sail which collects from the winds that sweep along the water. This energ .....

.... acid. Among the most important aldohexoses are glucose, mannose, and galactose; fructose is a ketohexose. Several derivatives of are important. Ascorbic acid (vitamin C) is derived from glucose. Important sugar alcohols (alditols), formed by the reduction of (i.e., addition of hydrogen to) a monosaccharide, include sorbitol (glucitol) from glucose and mannitol from mannose; both are used as sweetening agents. Glycosides derived from are widespread in nature, especially in plants. Amino sugars (i.e., sugars in which one or two hydroxyl groups are replaced with an amino group, -NH2) occur as components of glycolipids and in the chitin of arthropo .....

.... bats some characteristics vary greatly but the Little Brown Bat is a good example of a bat. It has fur on its body, large naked ears, its rear legs have claws, it has a tail membrane, and it has the most distinguishing feature of a bat, wings (Lauber 9). The upper arm of the bat is short while the forearm is very long. The wrist is very small and from it comes the thumb and the four longer fingers. The thumb is short and used for climbing or walking. The fingers are long and thin. Interlocking the fingers is the wing. This set up of having the fingers in the wing gives the bat amazing flight maneuverability (Honders 22). These bones look .....

.... in trimesters, three month intervals. After about thirty hours the cell divides for the first time. It is continuously moving towards the uterus where it will call home for the next nine months. After about two days it has divided to having about eight cells. After four days it is in the uterus and has to "land" somewhere and attach itself to the endometrium. The eighth day is when implantation occurs. The fertilized egg then implants itself on the endometrium, the uterine lining, and begins to grow. The cell begins to grow and develop. By the 12th day the blastocyst has approximately two thousand cells in it. It has had .....

.... triangular ones. Aside from the isometric system, there is also; a tetragonal, orthorhombic, monoclinic, triclinic and hexagonal system. Crystals may form when a solution of a substance evaporates. Crystals may also form when a vapor or molten substance solidifies. Allotropes are different forms of the same element. For Example, oxygen has two allotropes, normal oxygen and ozone. Pure carbon also has two allotropes, diamond and graphite. A crystal of diamond is in fact a single giant molecule in which every carbon atom is linked to four other, by four equal, strong bonds. These bonds are arranged tetrahedrally round each atom and there are no pla .....