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Helium
Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. Its boiling and melting point are the lowest among all the elements. It is the second lightest and second most abundant element in the observable universe (hydrogen is the lightest and most abundant). It is present at about 24% of the total elemental mass, which is more than 12 times the mass of all the heavier elements combined. Its abundance is similar to this in both the Sun and in Jupiter, due to the very high nuclear binding energy (per nucleon) of helium-4, with respect to the next three elements after helium. This helium-4 binding energy also accounts for why it is a product of both nuclear fusion and radioactive decay. The most common isotope of helium in the universe is helium-4, the vast majority of which was formed during t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zheng He
Zheng He (; 1371–1433 or 1435) was a Chinese mariner, explorer, diplomat, fleet admiral, and court eunuch during China's early Ming dynasty. He was originally born as Ma He in a Muslim family and later adopted the surname Zheng conferred by the Yongle Emperor. Commissioned by the Yongle Emperor and later the Xuande Emperor, Zheng commanded seven expeditionary treasure voyages to Southeast Asia, South Asia, West Asia, and East Africa from 1405 to 1433. According to legend, his larger ships carried hundreds of sailors on four decks and were almost twice as long as any wooden ship ever recorded. As a favorite of the Yongle Emperor, whom Zheng assisted in the overthrow of the Jianwen Emperor, he rose to the top of the imperial hierarchy and served as commander of the southern capital Nanjing. Early life and family Zheng He was born Ma He () to a Muslim family of Kunyang, Kunming, Yunnan, during the Ming dynasty of China. He had an older brother and four sisters. Zheng He' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
