Article: With nitrides containing aluminium, most often AlGaN and AlGaInN, even shorter wavelengths are achievable. Ultraviolet LEDs in a range of wavelengths are becoming available on the market. Near-UV emitters at wavelengths around 375395 nm are already cheap and often encountered, for example, as black light lamp replacements for inspection of anti-counterfeiting UV watermarks in some documents and paper currencies. Shorter-wavelength diodes, while substantially more expensive, are commercially available for wavelengths down to 240 nm. As the photosensitivity of microorganisms approximately matches the absorption spectrum of DNA, with a peak at about 260 nm, UV LED emitting at 250270 nm are to be expected in prospective disinfection and sterilization devices. Recent research has shown that commercially available UVA LEDs (365 nm) are already effective disinfection and sterilization devices. UV-C wavelengths were obtained in laboratories using aluminium nitride (210 nm), boron nitride (215 nm) and diamond (235 nm).

Question: What sort of LEDs are becoming more available on the market?
Ans: Ultraviolet

Article: Roman calendars show roughly forty annual religious festivals. Some lasted several days, others a single day or less: sacred days (dies fasti) outnumbered "non-sacred" days (dies nefasti). A comparison of surviving Roman religious calendars suggests that official festivals were organized according to broad seasonal groups that allowed for different local traditions. Some of the most ancient and popular festivals incorporated ludi ("games," such as chariot races and theatrical performances), with examples including those held at Palestrina in honour of Fortuna Primigenia during Compitalia, and the Ludi Romani in honour of Liber. Other festivals may have required only the presence and rites of their priests and acolytes, or particular groups, such as women at the Bona Dea rites.

Question: How many religious celebrations did Rome have?
Ans: forty

Article: By 1937, Japan controlled Manchuria and was ready to move deeper into China. The Marco Polo Bridge Incident on 7 July 1937 provoked full-scale war between China and Japan. The Nationalist and Communist Chinese suspended their civil war to form a nominal alliance against Japan, and the Soviet Union quickly lent support by providing large amount of materiel to Chinese troops. In August 1937, Generalissimo Chiang Kai-shek deployed his best army to fight about 300,000 Japanese troops in Shanghai, but, after three months of fighting, Shanghai fell. The Japanese continued to push the Chinese forces back, capturing the capital Nanking in December 1937 and committed which was known as Nanking Massacre. In March 1938, Nationalist forces won their first victory at Taierzhuang. but then the city of Xuzhou was taken by Japanese in May. In June 1938, Japan deployed about 350,000 troops to invade Wuhan and captured it in October. The Japanese achieved major military victories, but world opinionin particular in the United Statescondemned Japan, especially after the Panay Incident.

Question: What incident occured on July 7, 1937?
Ans: Marco Polo Bridge Incident

Article: Instruments have divided Christendom since their introduction into worship. They were considered a Catholic innovation, not widely practiced until the 18th century, and were opposed vigorously in worship by a number of Protestant Reformers, including Martin Luther (14831546), Ulrich Zwingli, John Calvin (15091564) and John Wesley (17031791). Alexander Campbell referred to the use of an instrument in worship as "a cow bell in a concert". In Sir Walter Scott's The Heart of Midlothian, the heroine, Jeanie Deans, a Scottish Presbyterian, writes to her father about the church situation she has found in England (bold added):

Question: What was the name of the book in which Jeanie Deans is the protagonist?
Ans:
The Heart of Midlothian