Here are four famous museums for family visits in Washington DC.

Dinosaur Museum

The museum features evidence, facts and tons of amazing sculptures of some of the most powerful and sometimes scary animals that ever controlled the Earth. The artists used real dinosaur bones to form the reproductions so they are extremely life-like.

Witte Museum

Originally established in 1926, this museum offers guests a comprehensive look at a more than 3-century span (跨度) of history. Called the center where nature, science and culture meet, the museum prides itself on providing guests with immersive (沉浸的) experiences, such as being taken back to cowboy days in the Heritage Center or digging through sand to find dinosaur bones.

The best part? The museum is constantly switching out some exhibits to better suit the season and provide guests with a different experience each time they visit.

Museum of Illusions

Step inside a completely new world at Orlando's newest exhibit the Museum of Illusions! This unique educational attraction is the perfect combination of fun and art, allowing visitors of all ages to test the limits of their mind. Focused on planting the seeds of curiosity, the astonishing images at the exhibitions remind guests that everything is not always as it seems.

World's Largest Toy Museum

Release your inner kid and visit the World's Largest l oy Museum, which will take you back in time with one million toys from the 1800's to today. You'll surely be excited to check out your "hero" toys from your childhood. The tours are self-guided and guests are allowed to leave and return during the same day.

A joint research team recently have developed a new electronic skin that is similar to human skin in strength, durability(耐久性) and sensitivity. The skin or e-skin may play an important role in next-generation personalized medicine, soft robotics and artificial intelligence.

"The ideal e-skin will mimic(模仿) the many natural functions of human skin, such as sensing temperature and touch, accurately and in real time, " says leading researcher Yichen Cai. However, making suitably flexible electronics that can perform such delicate tasks while also used repeatedly is challenging, and each material involved must be carefully engineered.

Most e-skins are made by putting an active sensor on the surface that attaches to human skin. However, the connection between them is often too weak, which reduces the durability and sensitivity of the material; otherwise, if it is too strong, it won't be flexible enough, making it more likely to break the circuit.

"The landscape of skin electronics keeps shifting at a remarkable pace," says Cai. "The discovery of 2D sensors has accelerated efforts to turn these quite thin but strong materials into functional, durable artificial skins. "

The new man-made skin built by the researchers could sense objects from 20 centimeters away. It could further make a quick response when touched in less than one tenth of a second." It is a striking achievement for an e-skin to maintain toughness after repeated use, " said Shen, "which mimics the softness and rapid recovery of human skin."

This type of e-skin could monitor a range of biological information, such as changes in blood pressure, which can be detected from movements of arms and legs. This data can then be shared and stored on the cloud via Wi-Fi.

"One remaining problem to the widespread use of e-skins lies in mass production of high-resolution sensors," adds group leader Vincent Tung" however, the latest technology offers new promise."

What does it take to become an astronaut? It's a question that's been asked since the start of the Space Age in the 1960s. In those days, pilots were considered the most well-trained professionals, so military fliers were first in line to go to space. More recently· people from a wide range of professional backgrounds -- doctors, scientists, and even teachers - have trained to live and work in near-Earth orbit. Even so, those selected to go to space must meet high standards.

People who want to become astronauts must be in top physical condition. Each country's space program has health requirements for its space travelers. They usually assess a candidate's fitness to withstand some pretty tough conditions. For example, a good candidate must have the ability to endure the rigors of lift-off and to function in weightlessness. All astronauts must have good visual acuity and normal blood pressure. Beyond that, there is no age limit. Most astronauttrainces are between the ages of 25 and 46, although older people have also flown to space later in their careers.

People who go to space are usually self-confident risk-takers, adept at stress management and multitasking. They also need to be able to work as part of a team for any given assignment. On Earth, astronauts are usually required to perform various public relations duties. such as speaking to the public, working with other professionals, and sometimes even testifying before government officials. So, astronauts who can relate well to many different kinds of people are seen as valuable team members.

Often, astronauts have a background as scientists and many have high-level degrees, like Ph. Ds. Others have military training or space industry expertise. Regardless of their background, once an astronaut is accepted into a country's space program, he or she goes through rigorous training to actually live and work in space.