Ceramic has a high melting point, so it is difficult to use conventional laser printing to make ceramics. The existing 3D-printed ceramic precursors, which are usually difficult to deform, also hinder the production of ceramics with complex shapes.

To overcome these challenges, the CityU team has developed a novel “ceramic ink,” which is a mixture of polymers and ceramic nanoparticles. The 3D-printed ceramic precursors printed with this novel ink are soft and can be stretched three times beyond their initial length. These flexible and stretchable ceramic precursors allow complex shapes, such as origami folding. With proper heat treatment, ceramics with complex shapes can be made.

The team was led by Professor Jian Lu, Vice-President (Research and Technology) and Chair Professor of Mechanical Engineering, who is a distinguished materials scientist with research interests ranging from fabricating nanomaterials and advanced structural materials to the computational simulation of surface engineering.

With the development of the elastic precursors, the research team has achieved one more breakthrough by developing two methods of 4D printing of ceramics.

4D printing is conventional 3D printing combined with the additional element of time as the fourth dimension, where the printed objects can re-shape or self-assemble themselves over time with external stimuli, such as mechanical force, temperature, or a magnetic field.

In this research, the team made use of the elastic energy stored in the stretched precursors for shape morphing. When the stretched ceramic precursors are released, they undergo self-reshaping. After heat treatment, the precursors turn into ceramics.

The resultant elastomer-derived ceramics are mechanically robust. They can have a high compressive strength-to-density ratio (547 MPa on 1.6 g cm-3 microlattice), and they can come in large sizes with high strength compared to other printed ceramics.

“The whole process sounds simple, but it’s not,” said Professor Lu. “From making the ink to developing the printing system, we tried many times and different methods. Like squeezing icing on a cake, there are a lot of factors that can affect the outcome, ranging from the type of cream and the size of the nozzle, to the speed and force of squeezing, and the temperature.”

It took more than two and a half years for the team to overcome the limitations of the existing materials and to develop the whole 4D ceramic printing system.

In the first shaping method, a 3D-printed ceramic precursor and substrate were first printed with the novel ink. The substrate was stretched using a biaxial stretching device, and joints for connecting the precursor were printed on it. The precursor was then placed on the stretched substrate. With the computer-programmed control of time and the release of the stretched substrate, the materials morphed into the designed shape.

In the second method, the designed pattern was directly printed on the stretched ceramic precursor. It was then released under computer-programming control and underwent the self-morphing process.

The innovation was published in the latest issue of top academic journal Science Advances under the title “Origami and 4D printing of elastomer-derived ceramic structures.” All research team members are from CityU, including Dr LIU Guo, Research Assistant, Dr ZHAO Yan, Senior Research Associate, and Dr WU Ge, Research Fellow.

“With the versatile shape-morphing capability of the printed ceramic precursors, its application can be huge!” said Professor Lu. One promising application will be for electronic devices. Ceramic materials have much better performance in transmitting electromagnetic signals than metallic materials. With the arrival of 5G networks, ceramic products will play a more important role in the manufacture of electronic products. The artistic nature of ceramics and their capability to form complex shapes also provide the potential for consumers to tailor-make uniquely designed ceramic mobile phone back plates.

Furthermore, this innovation can be applied in the aero industry and space exploration. “Since ceramic is a mechanically robust material that can tolerate high temperatures, the 4D-printed ceramic has high potential to be used as a propulsion component in the aerospace field,” said Prof Lu.

Riding on the breakthrough in material and 4D-printing technique advancement, Prof Lu said the next step is to enhance the mechanical properties of the material, such as reducing its brittleness.

The 1992 discovery of exoplanets orbiting other stars has sparked interest in understanding the composition of these planets to determine, among other goals, whether they are suitable for the development of life. Now a new evaluation of data from the exoplanet-hunting Kepler Space Telescope and the Gaia mission indicates that many of the known planets may contain as much as 50% water. This is much more than the Earth’s 0.02% (by weight) water content.

“It was a huge surprise to realize that there must be so many water-worlds,” said lead researcher Dr Li Zeng (Harvard University),

Scientists have found that many of the 4000 confirmed or candidate exoplanets discovered so far fall into two size categories: those with the planetary radius averaging around 1.5 that of the Earth, and those averaging around 2.5 times the radius of the Earth.

Now a group of International scientists, after analyzing the exoplanets with mass measurements and recent radius measurements from the Gaia satellite, have developed a model of their internal structure.

“We have looked at how mass relates to radius, and developed a model which might explain the relationship,” said Li Zeng. The model indicates that those exoplanets which have a radius of around x1.5 Earth radius tend to be rocky planets (of typically x5 the mass of the Earth), while those with a radius of x2.5 Earth radius (with a mass around x10 that of the Earth) are probably water worlds.”

“This is water, but not as commonly found here on Earth,” said Li Zeng. “Their surface temperature is expected to be in the 200 to 500 degree Celsius range. Their surface may be shrouded in a water-vapor-dominated atmosphere, with a liquid water layer underneath. Moving deeper, one would expect to find this water transforms into high-pressure ices before we reaching the solid rocky core. The beauty of the model is that it explains just how composition relates to the known facts about these planets.”

Li Zeng continued, “Our data indicate that about 35% of all known exoplanets which are bigger than Earth should be water-rich. These water worlds likely formed in similar ways to the giant planet cores (Jupiter, Saturn, Uranus, Neptune) which we find in our own solar system. The newly-launched TESS mission will find many more of them, with the help of ground-based spectroscopic follow-up. The next generation space telescope, the James Webb Space Telescope, will hopefully characterize the atmosphere of some of them. This is an exciting time for those interested in these remote worlds.”

Professor Sara Seager, Professor of Planetary Science at Massachusetts Institute of Technology, and deputy science director of the recently-launched TESS (Transiting Exoplanet Survey Satellite) mission, which will search for exoplanets, said:

“It’s amazing to think that the enigmatic intermediate-size exoplanets could be water worlds with vast amounts of water. Hopefully atmosphere observations in the future — of thick steam atmospheres — can support or refute the new findings.”

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Aquaculture is the world’s fastest growing food sector, surpassing the global capture fisheries production in 2014. It provides more than 50 percent of the food supply to humans; however, it poses several environmental concerns. Aquaculture feed (aquafeeds) draws on 70 percent of the world’s fishmeal and fish oil, which is obtained from small, ocean-caught fish such as anchovies, sardines, herring, menhaden, and mackerel¬, that are essential to the lower end of the marine food chain. Analysts project that by 2040, the demand for fishmeal and fish oil will exceed supply. Aquafeeds also draw on large amounts of soy and corn from industrial farms, which pose other environmental concerns due to the use of fertilizers and potential runoff into rivers, lakes and coastal waters. In addition, aquafeeds may trigger nutrient pollution in aquaculture effluent, as fish are unable to fully digest soy and corn, which are major feed ingredients.

To address the environmental sustainability concerns regarding aquafeed, a Dartmouth team has been developing sustainable feeds for Nile tilapia, which examine the effectiveness of replacing fishmeal and fish oil with different types of marine microalgae. Marine microalgae are excellent sources of essential amino acids, minerals, vitamins, and omega-3 fatty acids, and can therefore, meet the nutrient requirements of fish. Omega-3 fatty acids are important for maintaining fish health; they also have neurological, cardiovascular and anti-cancer benefits to humans.

The Dartmouth research team’s latest work replaces fishmeal with a marine microalga co-product, Nannochloropsis oculata, which is rich in both protein and omega-3 fatty acids, including eicosapentaenoic acid, that are essential to fish growth and quality. The co-products are left-over algae meal, after the oils have been extracted from commercially-grown algae biomass to manufacture nutraceuticals, chemicals and fuel applications. The co-product is available at commercial scale and continued increases in supply are expected. The study’s findings show promise in replacing conventional protein ingredients in tilapia feeds.

The results demonstrated that the co-product had higher protein content than the whole cells but had lower digestibility than whole cells. The co-product showed the highest digestibility of lysine, an essential amino acid that is often deficient in terrestrial crop-based aquafeed ingredients, as well as the highest eicosapentaenoic acid (EPA) digestibility.

The team also evaluated several feeds with varying percentages of co-product replacing fishmeal. When 33 percent of fishmeal was replaced with the co-product, the Nile tilapia had fish growth and a feed conversion ratio and survival rate similar to those on the reference diet for which fishmeal was seven percent of the diet. The team hypothesizes that the co-product may need to be enhanced with enzyme(s) to maximize nutrient availability and counter the lower digestibility observed in the experiment.

“The possibilities for developing a sustainable approach to aquaculture are exciting. Our society has an opportunity to shift aquafeed’s reliance on fish-based ingredients to a fish-free product that is based on marine microalgae, and our findings provide new insight into how we can get there,” says lead author, Pallab Sarker, a research assistant professor at Dartmouth.

The research builds on the team’s earlier work developing a marine microalga feed for Nile tilapia made from Schizochytrium sp., which evaluated how the feed affected digestibility and growth. The results demonstrated that Schizochytrium sp. was highly digestible lipid and DHA, an omega 3 fatty acid source for tilapia. The tilapia not only had higher weight gain but better feed conversion compared to those on a control diet containing fish oil, when the Schizochytrium sp fully replaced the fish oil.

As part of the team’s goal to eliminate aquafeed’s reliance on marine fish and terrestrial crop inputs, they are combining Nannochloropsis co-product with other marine microalgae to make aquaculture feeds more sustainable.

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It took a team of researchers led by the U.S. Food and Drug Administration to confirm the contaminant, a toxin structurally similar to heparin that was traced to a Chinese supplier. But detection of the impurity required “a tremendous effort by heavy hitters in the chemistry world,” said Jason Dwyer, associate professor of chemistry at the University of Rhode Island.

After nearly eight years of research, Dwyer has developed a simpler and quicker method for detecting the impurity in heparin, along with creating a process that could have wider benefits. His research was unveiled today in the online journal Nature Communications, part of the suite of journals from the publisher of Nature.

“There are tests that are much more sophisticated and expensive to detect the impurity,” said Dwyer, of Providence, R.I. “What we were able to do is — in a very inexpensive and rapid fashion — fingerprint heparin and tell when there is a contaminant in it.”

The research, “Surveying Silicon Nitride Nanopores for Glycomics and Heparin Quality Assurance,” could also be used to analyze the entire class of molecules to which heparin belongs with broad use in biomedical diagnostics, pharmaceuticals and environmental sensing. Dwyer’s wider studies of sugars were bolstered in July by a $318,000 grant from the National Science Foundation.

For example, Dwyer said, the new detection technique could serve as a quality assurance tool across the pharmaceutical industry, especially with an increased push to develop more sugar-based drugs, such as heparin. “Sugars are incredibly important,” said Dwyer, whose research in the past has garnered publication in the high-profile journals Nature and Science. “They’re how bacteria communicate with each other. They’re how we’re going to be designing a lot of new drugs. So we need new tools to analyze sugars.”

To develop the new detection technique, Dwyer turned to a sensing method proven in the sequencing of DNA and proteins. The sensor consists of a hole, or nanopore, less than a thousandth the thickness of a human hair, sitting on a membrane that is even thinner, and tests substances at the smallest detectable level — a single molecule.

While the sensor, a solid-state silicon nitride nanopore, worked well for DNA, it had to be retooled for sugar molecules, which are far more complex, said Dwyer, whose group was one of the first to focus on sugars.

Starting in 2010, the project developed along with other work by Dwyer’s team. It took years to fabricate and fine-tune devices, refine the nanopore and prevent the opening from clogging. “A fair number of students have worked on this project over the years,” Dwyer said. “We have not relented. We butted our heads against the wall for a period of time and we realized we needed to do a fair amount of fundamental work before we could get to the point of detecting.”

One unexpected problem was solved by Buddini Karawdeniya, lead author of the paper who completed her doctorate in chemistry at URI in the spring. When she attempted to run sugar molecules through the nanopore, they went backwards. “In 1996, people figured out how DNA could be sensed with a nanopore,” Dwyer said. “There were some oddities but it worked the way it was expected. Sugars right off the bat did not act as expected. So Buddini had to look at what had been done for 20 years, but know she had to start over at some level.”

With the 2008 crisis, researchers had managed to identify and detect the oversulfated chondroitin sulfate contaminant, which was nearly identical to the heparin. Using the fine-tuned nanopore, Dwyer’s research looked at both samples, determined that the signals they generated were 99-percent identical, and devised analysis techniques to use the 1-percent difference to reliably detect the impurity.

“The test we came up with takes about 20 minutes,” he said, “and works at clinically relevant concentrations.”

The goal is to make detection of the impurity even quicker, down to minutes and seconds. At the same time, the device will have to be adapted for a commercial user who may lack the expertise of a researcher in a technology development lab. Also, the tool would have to perform accurately in a less-controlled environment.

“This is where research starts to transition into development, and we start to refine the conditions and the devices even more,” Dwyer said. “Often discovery is the easiest part. Refining it for the end user takes time.”

The nanopore that came out of the heparin research was designed with that in mind. It uses technology similar to that found in nearly every piece of consumer electronics, said Dwyer, so there is already an industry ready to produce the sensors on a large scale.

“We always try to think about the consumer market,” he said. “What we do in the lab is one thing — and it is a vital thing — but how do we translate it into the real world?”

This material is based upon work supported by the National Science Foundation under Grant No. CBET-1150085.

They combined auxin-inducible “protein knockdown” with a synthetic antibody to not only observe fluorescent proteins in living cells but also to rapidly remove them in a temporally controlled manner.

Perhaps the most important basic component of all cells are proteins that perform a wide variety of functions in cells and tissues. In order to clarify the physiological roles of proteins, they are often linked to a green fluorescent protein (GFP) via targeted genetic manipulation, which makes them visible under the microscope. The observation of such GFP-linked proteins in living cells allows initial conclusions about the function of the protein. However, the exact function of a protein can often only be determined when the protein is removed and the resulting consequences become visible in cells, tissues or model organisms.

This is usually achieved by knockout of the protein on the genetic level. However, the functions of essential proteins cannot be examined in this way, because the cell or the model organism would not be viable. Instead, an approach is needed that allows removing proteins from cells only at a specific time. Such a targeted temporary degradation of proteins occurs naturally in plants and is mediated by the plant hormone auxin. After genetic manipulation, the underlying mechanism can also be applied to animal and human cells.

Dr. Jörg Mansfeld’s research group has developed a novel AID-nanobody in order to not only observe GFP-linked proteins in living cells, but to also rapidly degrade them in a targeted manner for functional analysis. For this purpose, the auxin recognition sequence (AID) was linked to a GFP recognizing antibody that is structurally-related to camelid antibodies (nanobody). It could be shown that this so-called AID-nanobody allows the almost complete degradation of GFP-linked proteins in human cell culture after the addition of auxin. The possibility to follow the degradation of the protein “live” under the microscope makes functional analysis much easier.

In collaboration with the research group of Dr. Caren Norden, it was shown that the AID-nanobody can also be successfully used in the model organism zebrafish. Using the AID-nanobody in zebrafish demonstrated for the first time that an auxin-mediated protein knockdown can also be implemented in a complex vertebrate model.

“Our work is an excellent example of biotechnology, in which different naturally occurring principles such as fluorescent GFP from algae, auxin-dependent protein degradation from plants and the nanobody from camelids are combined to answer previously inaccessible research questions,” said Dr. Katrin Daniel from the Mansfeld Lab, commenting on the results of the research project.

The successful work highlights the synergies that can be achieved, when groups from different research institutes at the Dresden Science Campus work closely together.

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