Leon，12，was born without fingers on his left hand. That didn't stop him from being able to do many tasks. But Leon could not grasp more than one object at a time. So Leon's father，Paul，created a prosthesis（义肢），using a3-D printer. Now Leon has fingers that can open and close. "It was a do-it-yourself，father and son adventure，" says Paul.

When Leon was a baby，his doctor advised his parents not to give him a prosthetic hand until he was in his early teens. "The doctor said Leon should first learn to get full use of the hand he was born with，"says Paul. As Leon got older，his father considered buying a prosthetic hand，which can cost as much as $30，000. Then Paul found a more affordable solution.

One day，Paul discovered a video on the Internet about Robohand，a prosthesis created by a 3--D printer. He downloaded the free instructions and called Robohand's creators for advice. They told him all he needed was a 3-D printer-which costs around $2，000 and some materials.

Luckily，Leon's school had recently bought a 3-D printer and it offered to help Paul build the hand for Leon. "We used a soccer shin pad（护胫），cardboard，and tape. They cost about $10，"says Paul.

With his new hand，Leon can do things better. "I can help my mom more，because now I can carry two grocery bags，"he says.

Leon's father has already built several hands for Leon. Leon helps design each one. He says there's one thing in particular that he wants to do with a future prosthesis. "The goal，"he tells the reporter from the local evening paper，"is to be able to tie my shoelaces（鞋带）".

   What makes us human？Is it our thoughts？Our emotions？Our behavior？

All of these things make us who we are，but at the center of it all lies the genome — the genes inside our bodies that determine everything from our hair color to our intelligence. But if we could change our genome，would we still be human？

Recently，a group of scientists from the US and South Korea worked together to successfully“edit”a human embryo（胚胎）and remove a genetic mutation（变异）that would have led to heart disease. This was achieved with the help of CRISPR-a gene — editing tool that allows scientists to edit the genome by cutting，changing or adding to parts of it.

Scientists involved in DNA editing are certain about the good of their work，and hope that in the future，diseases could simply be“edited out”.

However，others aren't so sure. People are worried that the science could be used not only to remove life-threatening illness，but also to make a“perfect”baby whose DNA has been chosen to improve its intelligence or other qualities. They say that this is a shallow way of thinking about raising children.

“It makes you think about who we are as people，and it makes you ask if humans should use the kind of power…that is changing human evolution（进化），”Jennifer Doudna of the University of California said.

Still，others worry that DNA editing could be turned into an expensive service that would only be available to the people who could afford it. That might mean the rich would be given another advantage in a world where they already have plenty of them.

“You could find wealthy parents buying the technology for their children, leading to even greater inequality than we already live with,”Marcy Darnovsky, director of the San Francisco Center for Genetics and Society, said.

   Would you buy a car that can release calming smells into the air when you are stuck in heavy traffic? Would you buy a robot that smells like a human being?

Many people have seen the 3-D computer-made environments of virtual reality（虚拟现实）. Now these virtual worlds will not just look and sound real. Researchers have created VR environments that even smell like the real ones. With the new technology, users open a virtual door and step into a new environment, like a rainforest. After they enter this virtual world, special equipment releases forest-like smells into the air to make the experience feel more real.

Suzanne Fisher-Murray said, “It is a really wonderful experience that you have because you’re exploring this environment and you have smells with it.”

In the United States, Smell-O-Vision was designed to provide smells during the showing of a movie. The Smell-O-Vision system was once popular in the 1960s. Now, Emanuela Maggioni says it is close to becoming popular again. “It connects emotions and memories with the sense of smell,” Maggioni said. “It is unbelievable what we can do with the technology.”

The uses of smell technology are not just limited to films and the performing arts. Researchers showed a computer program where users could imagine themselves driving a car. The system included a special smell-spraying machine. Dmitrijs Dmitrenko said, “We want to deliver the smell of lavender(薰衣草) every time the person drives over the speed limit. We choose lavender because it’s a very calming smell.”

Scientists are experimenting with smells instead of sounds or image-based alerts on telecommunications equipment. And businessmen have already used smells to influence people’s behavior. “Not only in stores, but also in other places you can create and stimulate(刺激) immediate purchase,” Maggioni said. “So you’re in a library and when you smell coffee you will unconsciously have the need to drink a coffee.”

   Nature has its own way of balancing itself out，but when we humans get involved，we tend to throw things out of control. Forests and oceans are natural carbon sinks that absorb carbon dioxide from the atmosphere, but since we’ve been pumping too much into the air, those sinks can’t keep up. Scientists at the Max Planck Institute for the Advancement of Science in Germany, led by biologist Tobias Erb，have figured out a way to supercharge plants to make them better at absorbing carbon dioxide, which could be a key defense against climate change.

Erb and his team figured out a way to make plants more efficient（效率高的）at absorbing carbon, so that they consumed more carbon in a shorter amount of time. “If you think about plants, they are efficient carbon dioxide -fixing filters, but they are not fast,” Erb said. “I think there is a chance to improve existing biology with synthetic（人造的）biology.”

Erb’s team identified 17 enzymes（酶）from nine different organisms, re-engineering three of them, which had enlarged carbon consumption. When those enzymes worked together as a team, they worked better at not only plants’ natural enzymes, but also themselves individually.

Existing enzymes in plants consume about 5 to 10 molecules（分子）of carbon dioxide per second. The team of enzymes that Erb used consumed 80 molecules per second.

So far, these enzymes have only been tested in test tubes in the lab, but the next step is real world testing where the enzymes would be introduced into plants to see if the same result occurs. If those tests show that plants really can be supercharged, we will have a new tool in the fight against climate change where not only do we protect the amazing carbon-absorbing forests we have, but we also apply these super plants or an artificial leaf technology using the enzymes into other fields.

   You'll probably never go to Mars or sing on the stage with The Rolling Stones. But if virtual reality （VR）ever lives up to its promise, you might be able to do all these things - and many more - without even leaving your home.Unlike real reality, virtual reality means simulating（模拟）bits of our world. Apart from games and entertainment, it's long been used for training airline pilots and surgeons and for helping scientists to figure out difficult problems such as the structure of protein molecules（蛋白质分子）. Then how does it work?

Close your eyes and think of virtual reality and you probably picture something like this:a man wearing a wrap-around headset and data gloves wired into a powerful workstation or supercomputer. What distinguishes VR from an ordinary computer experiences the nature of the input and output. While an ordinary computer uses things like a keyboard, a mouse, or speech recognition for input, VR uses sensors that detect how your body is moving. A PC displays output on a screen while VR uses two screens （one for each eye） , surround-sound speakers, and maybe some forms of touch and body feedback as well.

VR has been routinely used by scientists,doctors, engineers, architects, archaeologists, and the military for about the last 30 years. Difficult and dangerous jobs are hard to train for. How  can you safely practice taking a trip to space, making a parachute jump, or carrying out brain surgery? All these things are obvious candidates for virtual reality applications.

Like any technology, virtual reality has both good and bad points. Critics always raise the risk that people may be addicted to alternative realities to the point of ignoring their real-world lives, but this criticism has been leveled at everything from radio and TV to computer games and the Internet. Like many technologies, VR takes little or nothing away from the real world: you don't have to use it if you don't want to.