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刘俊良

Scanning Tunneling Microscopes (S.T.M)

 Scanning Tunnelling Microscope as known as S.T.M is a ultimate microscope that has the power to view individual atoms . Its development in 1981 earned its inventors, Gerd Binnig and Heinrich Rohrer won the Nobel Prize in Physics in 1986. The microscope is based on the concept of quantum tunneling.When a conducting tip is brought very near to the surface to be examined, a bias (voltage difference) applied between the two can allow electrons to tunnel through the vacuum between them. The resulting tunneling current is a function of tip position, applied voltage, and the local density of states of the sample.^[4] Information is acquired by monitoring the current as the tip's position scans across the surface, and is usually displayed in image form. STM can be a challenging technique, as it requires extremely clean and stable surfaces, sharp tips, excellent vibration control, and sophisticated electronics, but nonetheless many hobbyists have built their own scanning tunneling microscope. So it was hard to use a STM because it requires absolute control of the mechanism.

Zhang Heng (張衡)

The famous Chinese inventor Zhang Heng was a Chinese astronomer, mathematician, inventor, geographer, cartographer, artist, poet, statesman, and literary scholar from Nanyang, Henan. He lived during the Eastern Han Dynasty (AD 25–220) of China.He was educated in the capital cities of Luoyang and Chang'an, and began his career as a minor civil servant in Nanyang. Eventually, he became Chief Astronomer, Prefect of the Majors for Official Carriages, and then Palace Attendant at the imperial court. His uncompromising stances on certain historical and calendrical issues led to Zhang being considered a controversial figure, which prevented him from becoming an official court historian. His political rivalry with the palace eunuchs during the reign of Emperor Shun (r. 125–144) led to his decision to retire from the central court to serve as an administrator of Hejian, in Hebei. He returned home to Nanyang for a short time, before being recalled to serve in the capital once more in 138. He died there a year later, in 139. Zhang applied his extensive knowledge of mechanics and gears in several of his inventions. He invented the world's first water-powered armillary sphere, to represent astronomical observation improved the inflow water clock by adding another tank;and invented the world's first seismometer, which discerned the cardinal direction of an earthquake 500 km (310 mi) away. Furthermore, he improved previous Chinese calculations of the formula for pi. In addition to documenting about 2,500 stars in his extensive star catalogue, Zhang also posited theories about the Moon and its relationship to the Sun; specifically, he discussed the Moon's sphericity, its illumination by reflecting sunlight on one side and remaining dark on the other, and the nature of solar and lunar eclipses. His fu (rhapsody) and shi poetry were renowned and commented on by later Chinese writers. Zhang received many posthumous honors for his scholarship and ingenuity, and is considered a polymath by some scholars. Some modern scholars have also compared his work in astronomy to that of Ptolemy (AD 86–161).

Science and Math

SORRY,everyone sorry. I have long time no post. Today I will talk about the relationships of science and math. Once Felix Klein said that math can help science, music, philosophy and many much more. Today I will talk with all of us short because I have a exam to tackle. The conclusion of today is that math and help science. So everyone please remember that. Thank you.