【推荐1】As the former great employee of NASA, Katherine Johnson, whose life was described in the movie Hidden Figures, died on February 24, 2020, aged 101.

“NASA is deeply saddened by the loss of a leader from our pioneering days,” said NASA administrator Jim Bridenstine on the webpage of NASA. “Ms. Johnson helped our nation push the boundaries of space and she also played an important role in opening doors for women and people of color to explore space. At NASA we will never forget her courage and leadership and the achievements we could not have reached without her.”

Johnson was born in West Virginia in 1918. She graduated from West Virginia State University with a major in mathematics and became a teacher at a public school. She was also the first African-American woman to attend graduate school in mathematics at West Virginia University until she left school to focus on raising children.

Her life changed in 1952 after a long career break. A relative told her about open positions at the all-black West Area Computing section at the National Advisory Committee for Aeronautics’ Langley laboratory, and she began to work: for the aerospace (航空航天) industry at Langley the next year. NASA depended on humans for complicated aerospace calculation as there was no high-functioning electronic computer. Female mathernaticians usually took the job as their salary was lower. Johnson was one of those African-American human computers.

Johnson was initially in charge of aerospace analysis and then a space development mission when NASA was launched in 1958. Then she worked for the 1961 suborbital (亚轨道的) flight of astronaut Alan Shepard. Johnson continued to sit for missions after she retired in 1986. Her hidden achievements were finally publicized when Barack Obama awarded her the Presidential Medal of Freedom in 2015 and her dramatic life was made into a movie.

【推荐3】We take for granted many of the materials used in modern life. However, without major advances in chemistry, many everyday things would not exist. This is why the invention of the periodic table of the elements (元素周期表) was so important. It really opened the door to many future achievements in chemistry and is still very much in use today.

Dmitri Mendeleev (1834-1907) of Russia is credited with the invention of the first reliable periodic table. In the middle of the 19th century, only 63 elements had been found. Mendeleev was eager to increase our knowledge of them. He wrote down the atomic mass (原子质量) of each element on cards and reorganised them again and again. After several months, he realized that the physical and chemical characteristics of elements were related to their atomic mass. So he lined them up in order of their atomic mass from light to heavy and then put those with similar characteristics in columns.

Mendeleev’s road to science success wasn’t an easy one. He lost his father at a young age and his large family was poor. Luckily, he had a strong-willed mother who made his education her top priority (优先的事). She moved several times so that Mendeleev could go to a good university. After being rejected many times, Mendeleev began his studies in 1850.

Unfortunately, this wasn’t the end of his troubles. Mendeleev suffered from a serious illness for many years, during which time he worked from bed. In spite of his misfortunes, Mendeleev was able to make great achievements in science through his determination to succeed in his work.

Mendeleev was not only an excellent chemist, but also a pioneer in shipbuilding and even suitcase-making. He found a special material that helped him make excellent suitcases that were highly valued. And he also had a hand in building the world’s first Arctic icebreaker, the Yermak. It played a vital part in the development of modern scientific shipping for trade and war.