A new method called “reactive 4D printing” creates objects that can take on alternate forms in response to changes in temperature, electric current, or stress.

The method could bring soft robots and biomedical implants that reconfigure themselves upon demand closer to reality.

The researchers first reported their ability to make morphing structures in a mold in 2018. But using the same chemistry for 3D printing limited structures to shapes that sat in the same plane. That meant no bumps or other complex curvatures could be programmed as the alternate shape.

Overcoming that limitation to decouple the printing process from shaping is a significant step toward more useful materials, says Rafael Verduzco, an associate professor of chemical and biomolecular engineering and of materials science and nanoengineering at Rice University .

“These materials, once fabricated, will change shape autonomously,” Verduzco says. “We needed a method to control and define this shape change. Our simple idea was to use multiple reactions in sequence to print the material and then dictate how it would change shape. Rather than trying to do this all in one step, our approach gives more flexibility in controlling the initial and final shapes and also allows us to print complex structures.”

The lab’s challenge was to create a liquid crystal polymer “ink” that incorporates mutually exclusive sets of chemical links between molecules. One establishes the original printed shape, and the other can be set by physically manipulating the printed-and-dried material. Curing the alternate form under ultraviolet light locks in those links.

Once the two programmed forms are set, the material can then morph back and forth when, for instance, it’s heated or cooled.

The researchers had to find a polymer mix that could be printed in a catalyst bath and still hold its original programmed shape.

There were a lot of parameters we had to optimize—from the solvents and catalyst used, to degree of swelling, and ink formula—to allow the ink to solidify rapidly enough to print while not inhibiting the desired final shape actuation,” Barnes says.

One remaining limitation of the reactive 4D printing process is the ability to print unsupported structures, like columns. To do so would require a solution that gels just enough to support itself during printing, she says. Gaining that ability will allow researchers to print far more complex combinations of shapes.

“Future work will further optimize the printing formula and use scaffold-assisted printing techniques to create actuators that transition between two different complex shapes,” Barnes says. “This opens the door to printing soft robotics that could swim like a jellyfish, jump like a cricket, or transport liquids like the heart.”

Today’s 3D printing creates items from a wide variety of materials — plastic, ceramic, glass, metal, and even more unusual ingredients such as chocolate and living cells. The machines work by setting down layers of material just like ordinary printers lay down ink, except 3D printers can also deposit flat layers on top of each other to build 3D objects.

“Today, this technology can be found not just in industry, but [also] in households for less than $1,000,” said lead study author Dan Raviv, a mathematician at MIT. “Knowing you can print almost anything, not just 2D paper, opens a window to unlimited opportunities, where toys, household appliances and tools can be ordered online and manufactured in our living rooms.”

Now, in a further step, Raviv and his colleagues are developing 4D printing, which involves 3D printing items that are designed to change shape after they are printed. [The 10 Weirdest Things Created By 3D Printing]

“The most exciting part is the numerous applications that can emerge from this work,” Raviv told Live Science. “This is not just a cool project or an interesting solution, but something that can change the lives of many.”

In a report published online today (Dec. 18) in the journal Scientific Reports, the researchers explain how they printed 3D structures using two materials with different properties. One material was a stiff plastic, and stayed rigid, while the other was water absorbent, and could double in volume when submerged in water. The precise formula of this water-absorbent material, developed by 3D-printing company Stratasys in Eden Prairie, Minnesota, remains a secret.

The researchers printed up a square grid, measuring about 15 inches (38 centimeters) on each side. When they placed the grid in water, they found that the water-absorbent material could act like joints that stretch and fold, producing a broad range of shapes with complex geometries. For example, the researchers created a 3D-printed shape that resembled the initials “MIT” that could transform into another shape resembling the initials “SAL.”

“In the future, we imagine a wide range of applications,” Raviv said. These could include appliances that can adapt to heat and improve functionality or comfort, childcare products that can react to humidity or temperature, and clothing and footwear that will perform better by sensing the environment, he said.

In addition, 4D-printed objects could lead to novel medical implants. “Today, researchers are printing biocompatible parts to be implanted in our body,” Raviv said. “We can now generate structures that will change shape and functionality without external intervention.”

One key health-care application might be cardiac stents, tubes placed inside the heart to aid healing. “We want to print parts that can survive a lifetime inside the body if necessary,” Raviv said.

The researchers now want to create both larger and smaller 4D-printed objects. “Currently, we’ve made items a few centimeters in size,” Raviv said. “For things that go inside the body, we want to go 10 to 100 times smaller. For home appliances, we want to go 10 times larger.”

Raviv cautioned that a great deal of research is needed to improve the materials used in 4D printing. For instance, although the 4D-printed objects the researchers developed can withstand a few cycles of wetting and drying, after several dozen cycles of folding and unfolding, the materials lose their ability to change shape. The scientists said they would also like to develop materials that respond to factors other than water, such as heat and light.

Micrometeoroids that delivered stardust to asteroid 4 Vesta also carried water, researchers report.

The formation of our solar system was a messy affair. Most of the material that existed before its formation—material formed around other, long-dead stars—was vaporized, then recondensed into new materials.

But some grains of that material from before the sun’s birth still persist. These “stardust” grains arrived on Earth inside primitive meteorites.

IF ICY MICROMETEOROIDS DELIVERED WATER TO THE INNER SOLAR SYSTEM WHEN THE EARTH WAS STILL FORMING, THIS COULD BE ONE WAY THAT THE EARTH ENDED UP WITH ENOUGH WATER TO SUPPORT LIFE.”

Like our Earth,” says Nan Liu, an assistant research professor in physics and the Laboratory for Space Sciences at Washington University in St. Louis, “Vesta has a core, a mantle, and crust,” features that formed as the materials melted, differentiated, and coalesced into a single planet-like object.

And like Earth, micrometeoroids also pummel Vesta. The brightest asteroid in the night sky, Vesta orbits the sun in the asteroid belt between Mars and Jupiter.

Liu, along with Lionel Vacher, a postdoctoral researcher, and Ryan Ogliore, assistant professor of physics, studied samples of the Kapoeta meteorite for this research. Kapoeta fell to Earth in 1942 in what is now South Sudan, landing on a road in front of a British convoy during World War II. NASA’s Dawn mission to asteroid Vesta established a link between Vesta and the howardites, eucrites, and diogenites, groups of meteorites found on Earth.

The research team focused on small, dark inclusions in Kapoeta that seemed out of place, like pieces of clay in lava rock.

“They look completely different from surrounding material,” Liu says. They turned out to be microscopic meteoroids, less than 100 microns across (smaller than the thickness of a human hair), that landed on Vesta’s surface.

Liu used a mass-spectrometer microscope, the NanoSIMS, to search the inclusions for presolar material. Because stardust has a very different isotopic composition from material that formed within the solar system, it jumped out at her under the microscope.

HABITABLE PLANETS AROUND OTHER STARS MAY HAVE ACQUIRED THEIR WATER THROUGH SIMILAR MEANS.”

The stardust in asteroid Vesta is a unique record of ancient, galactic material delivered long ago to a body far from Earth. The researchers postulate that the micrometeoroids arrived at Vesta after the violent impacts of the Late Heavy Bombardment, about 3.5 billion years ago.

Vacher and Ogliore measured the chemical compositions of the micrometeoroids to understand in what type of environment they formed. They recognized minerals and textures that were linked to interactions between rock and water from melted ice.

One of the big questions is: How did water get on Earth?

We need a mechanism to bring ice from the outer solar system, where the temperature is low,” Vacher says. “This research shows that you can transport small micrometeoroids that contain ice to dry bodies that formed without water.”

The ancient record of these micrometeoroids’ impacts on Earth has been erased by weather and plate tectonics. The micrometeoroid record from asteroid Vesta may help to explain how water was delivered to the young Earth.

“If icy micrometeoroids delivered water to the inner solar system when the Earth was still forming, this could be one way that the Earth ended up with enough water to support life,” Ogliore says. “Habitable planets around other stars may have acquired their water through similar means.”

More analyses are needed to determine the when and the where. “Our next measurements will constrain when this wet material was delivered to Vesta, and where it came from: an icy asteroid, a comet or some other exotic source,” Ogliore says

The origin of water on Earth is the subject of a body of research in the fields of planetary science, astronomy, and astrobiology. Earth is unique among the rocky planets in the Solar System in that it is the only planet known to have oceans of liquid water on its surface. Liquid water, which is necessary for life, continues to exist on the surface of Earth because the planet is at a distance far enough from the Sun that it does not lose its water to the runaway greenhouse effect, but not so far that low temperatures cause all water on the planet to freeze.

Earth could not have condensed from the protoplanetary disk with its current oceans of water because the early inner Solar System was far too hot for water to condense. Instead, water and other volatiles must have been delivered to Earth from the outer Solar System later in its history. Modern geochemical evidence suggests that water was delivered to Earth by impacts from icy planetesimals similar in composition to modern asteroids in the outer edges of the asteroid belt.

Depression and anxiety have become major mental health concerns of modern society. Shockingly, depression and anxiety are some of the least treated mental disorders. This is because people shy away from treatment stating various reasons. Victims usually say, that they need some time so that they can get out of the clutches by themself, they don’t wanna take the pills, they are embarrassed to speak about it with the doctors. Whatever the reasons may be, depression and anxiety can stop people from doing their day to day activities or even lead to making fatal decisions if untreated at most cases. 

While treatment is the best option to get out of depression and prevent anxiety, reading some self-help books can be your trump card to beat depression and anxiety without any treatment. Even if it doesn’t help you get rid of them, it will be the best guide post treatment so that you don’t go into depression again. 

One of the best books which I would suggest is “The subtle art of not giving a fuck” authored by Mark Manson. The book stands apart from other motivational books by emphasizing us to accept our failure and limits while guiding how to live with them. This book addresses the depression and anxiety problems. Also the circumstantial reasons for falling prey to those disorders are discussed. Most victims when they read this book would be surprised by getting to know the long story before they ended up with depression and anxiety. The author also talks about the modern societal problems that are misleading people and making them more prone to anxiety and depression. 

This book is not limited to certain people as the author try to articulate the meaning of life while addressing the issues. If you are person who don’t prefer motivational books but want the message, then this book is for you.