Getting electricity has always been a problem for the 173 people living in Nuevo Saposoa, a small village in Peru, South America. However, things went from bad to worse in March 2015 after heavy rains damaged the only power cables in the area. The villagers were forced to use oil lamps, which are not only expensive but also dangerous because of the harmful gases they produce.

    Luckily, researchers at the University of Technology (UT) in Lima, Peru heard about their problem and found a wonderful solution. They made a lamp that can be powered by plants and soil, both of which can be easily found in the Amazonian rainforest where the village lies. The lamp takes energy from a plant growing in a wooden box and uses it to light up an LED light bulb.

    While that may sound amazing and even impossible, the science behind the idea is quite simple. As plants create their food (using the sun's energy, water and chemicals from the soil), they also produce waste which they return to the soil. Tiny animals in the soil eat this waste and they produce electrons—the building blocks of electrical energy. The UT team put special sticks inside the soil to capture the energy and keep it in the lamp's batteries for later use. The researchers say a single charge can power a 50-watt LED light for two hours —enough time for local villagers to get their evening work done.

    The university gave ten Plant Lamps to the villagers of Nuevo Saposoa in October 2015. So far, they have been a huge success! Elmer Ramirez, the UT professor who invented the lamp, believes the Plant Lamp could help improve the lives of many people, especially in small rainforest communities, 42% of whom have no electricity.

    O. Henry is one of the American famous short story writers. His novels expose (揭露) the darkness of capitalism (资本主义) from different points of view, describe the difficult life of lower class, and praise their friendship and love to happy life.

    As we all know, O. Henry's endings are always unexpected. He would suddenly change the inner world of the characters in an unbelievable way. For example, The Cop and the Anthem is one of the typical surprising endings of

O. Henrys novels. And O. Henry just used this way to expose the reality of being unable to distinguish the good from the bad.

    The artistic effects of O. Henry's endings don't always appear in the end. In The Cop and the Anthem, both an attractive woman and a well-dressed customer give readers a perfect feeling. In fact, they are not the people that we think, but they really exist in our society. Is everyone in upper-class noble, kind and well-behaved? Of course not, someone just puts their dirty behaviour under their beautiful mask. In short, O. Henry's endings expose the public moral (道德) of capitalism going from bad to worse in a humorous way.