Photo taken on Feb. 2, 2018 shows a piece of compressed wood (Top, C) and its original form (Bottom, C) at the University of Maryland, Maryland, the United States. U.S. researchers said Wednesday that they have developed a simple way to make wood as strong as steel or even titanium alloys, opening up possible applications in areas such as buildings, cars and airplanes. (Xinhua/Hua Xie)